text stringlengths 4 191k | embedding listlengths 384 384 |
|---|---|
Journal Pre-proof Lessons already learnt from the Covid-19 pandemic Letter to the Editor of The Journal of Thoracic Oncology Lessons already learnt from the Covid-19 pandemic
2020
MDJosé Sanz-Santos jsanzsantos@mutuaterrassa.cat
PhDRamón Rami-Porta
PhD, FETCSSergi Call
MD, PhDJosé Sanz-Santos
Department of Pulmonology
Hospital Universitari Mútua Terrassa
University of Barcelona
Terrassa (Barcelona)Spain
Department of Medicine
Medical School
University of Barcelona
BarcelonaSpain
Network of Centers for Biomedical Research in Respiratory Diseases (CIBERES) Lung Cancer Group
Terrassa (Barcelona)Spain
MDRamón Rami-Porta
Network of Centers for Biomedical Research in Respiratory Diseases (CIBERES) Lung Cancer Group
Terrassa (Barcelona)Spain
MDSergi Call
Department of Thoracic Surgery
Hospital Universitari Mútua Terrassa
University of Barcelona
Terrassa, BarcelonaSpain
MDJosé Sanz-Santos
Department of Thoracic Surgery
Hospital Universitari Mútua Terrassa
University of Barcelona
Terrassa, BarcelonaSpain
Department of Morphological Sciences
Medical School
Department of Pulmonology. Hospital
Unit of Human Anatomy and Embryology
Autonomous University of Barcelona
Bellaterra, BarcelonaSpain
Universitari Mútua Terrassa
Plaça Dr. Robert 508221Terrassa (Barcelona)Spain
Journal Pre-proof Lessons already learnt from the Covid-19 pandemic Letter to the Editor of The Journal of Thoracic Oncology Lessons already learnt from the Covid-19 pandemic
Journal of Thoracic Oncology
202010.1016/j.jtho.2020.04.012Received Date: 10 April 2020 Accepted Date: 10 April 2020Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. Please cite this article as: Sanz-Santos J, Rami-Porta R, Call S, Lessons already learnt from the This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1 Corresponding author:coronavirusCovid-19lung cancerthoracic malignancies Disclosure: Nothing to disclose
The first Covid-19 patient in Spain was registered on 31 st January 2020. Since then, the escalating growth of the disease has affected more than 150,000 patients, has caused over 15,000 deaths, and a similar number of health professionals has been infected. As of 10 th April 2020, Spain is the European country with the highest number of patients and the third in the world regarding deaths 1 .
The thoracic surgery service of our 400-bed hospital serves a population of 1,200,000 inhabitants, performs about 120 lung resections for lung cancer and over 90 surgical of delays are difficult to quantify, but most likely will jeopardize the fate of many patients. The workload, once we can resume normal activities, will be enormous.
The Covid-19 pandemic may not be the only one we will have to face in our professional lives. If there were another one, all measures should be taken to keep a section of the hospital clean, so that the regular activities could continue for as long as possible. Sooner or later patients have to be transferred to makeshift hospitals. If this is done in the early phase of the disease 2 , normal activities could be continued for much longer and priority cancer patients would benefit of timely treatment. The early testing of health personnel and patients and the use of adequate protective gear would prevent the dissemination of disease in the hospital, which has been catastrophic in our case. These measures would reduce the number of infections among the health care personnel, would maintain an area of the hospital clean, and would increase the capacity to continue the regular activities with non-Covid-19 patients.
explorations of the mediastinum per year. In early March, the commission in charge of the hospital organization during the pandemic restricted the outpatient clinic to the day-hospital for onco-hematologic treatments and the surgical activity to priority oncologic operations. However, with the exponential increase of Covid-19 patients, the outpatient clinics and the postsurgical recovery rooms had to be transformed into hospitalization wards and intensive care units, respectively, and the respirators of the operating rooms had to be used to ventilate Covid-19 patients. The result is that no surgery can be performed other than emergency cases and no new patients can be seen in the outpatient clinics. Our hospital is like a casualty hospital. All wards are filled with Covid-19 patients. Nearly 300 health professionals are infected and more are in quarantine for having been in close contact with infected patients or colleagues. Those who can still work are devoted exclusively to Covid-19 patients. Some patients have been externalized in a nearby hotel because there was no room in the hospital. Pulmonologists, thoracic surgeons and oncologists, who usually meet in tumor boards, are now working in improvised medical teams attending infected patients. There is only one thoracic 3 surgeon who controls the chest tubes and performs tracheostomies. Tumor boards are now conducted virtually, if there are patients to discuss. The numbers in surgical waiting lists and of patients waiting to be diagnosed are increasing. The consequences
Thoracic Surgery Outcomes Research Network, Inc. COVID-19 giuidance for triage of operations for thoracic malignancies: a consensus statement from Thoracic Surgery Research Network, the Society of Thoracic Surgeons and the American Association for Thoracic Surgery. 10.1016/j.jtcvs.2020.03.061J Thorac Cardiovasc Surg. Thoracic Surgery Outcomes Research Network, Inc. COVID-19 giuidance for triage of operations for thoracic malignancies: a consensus statement from Thoracic Surgery Research Network, the Society of Thoracic Surgeons and the American Association for Thoracic Surgery. J Thorac Cardiovasc Surg 2020. Doi: https://doi.org/10.1016/j.jtcvs.2020.03.061.
| [
0.018992163240909576,
-0.013020386919379234,
-0.07720022648572922,
-0.047034263610839844,
-0.00038572889752686024,
0.0005731135606765747,
-0.17936192452907562,
0.10932907462120056,
0.1256689429283142,
0.06922416388988495,
0.005555636715143919,
0.045733485370874405,
0.121086984872818,
0.147... |
Supplementary Table-1: SARS-CoV-2 variant spike proteins. Variants Pango Mutations Stabilization Length Furin Wuhan-Hu-1 A -2P, 6P, 6P-Mut7 1-1208 GSAS Alpha
GSAS Beta
B.1.1.7 del69-70, del144, B.1.351 L18FN501Y, A570D, D614G, P681H, T716I, S982A, D1118H 6P-Mut7 1-1208, D80A, D215G, del242-244, K417N, E484K, N501Y, D614G, A701V 6P-Mut7 1-1208
GSAS Gamma
P.1 L18FT20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I, V1176F
Supplementary Table-1: SARS-CoV-2 variant spike proteins. Variants Pango Mutations Stabilization Length Furin Wuhan-Hu-1 A -2P, 6P, 6P-Mut7 1-1208 GSAS Alpha
71C9CB3974FC78C276433CB30FF83E34Delta B.1.617.2 T19RG142Ddel156-157R158GL452RT478KD614GP681RD950N 6P6P-Mut7 1-1208 GSAS Omicron B.1.1.529 A67Vdel69-70T95IG142Ddel143-145del211ins214EPEG339DS371LS373PS375FK417NN440KG446SS477NT478KE484AQ493RG496SQ498RN501YY505HT547KD614GH655YN679KP681HN764KD796YN856KQ954HN969KL981F
Figure S1
: Previous quantitation of site-specific N-glycosylation on SARS-CoV-2 spike-protein trimer vary.Shown are the results from site-specific N-glycosylation analysis by standard MS-based glycoproteomic method on Wuhan-Hu-1 as reported by Watanabe et. al., 2020 [S1] (Report 1) ;Chawla et. al., 2022 [S2] (Report 2); Newby et. al., 2023 [S3] (Report 3); Shajahan et. al., 2020 [S4] (Report 4); Shajahan et. al., 2023 [S5] (Report 5); and Wang et. al., 2021 [S6] (Report 6), compared to results from DeGlyPHER (top 2 rows, 2P followed by 6P).A visual estimate from these reports is plotted here and compared at each N-glycosylation site.Variation in glycosylation pattern observed in different reports are apparent at many sites.Color-coding of "Report #", groups the reports based on research laboratories authoring them.Cited studies used either 2P stabilized mutant of SARS-CoV-2 spike-protein [S7, S8] or 6P stabilized mutant [S9], as indicated, except report 4 that used independently expressed S1 and S2 subunits of S-protein.Error bars are absent here because all the cited reports here except this study, have not estimated error in their calculations, presumably owing to low sampling.*Report 4 does not claim quantitation; thus, estimated values are from the types of glycoforms reported.Only this study and Report 1 have validated that S-proteins examined are well-folded trimers (using negative-stain electron microscopy).n.d.: glycosylation not determined.
Key:
Foldon, T4 fibritin trimerization domain [S10] HRV3C protease cleavage sequence (modified from [S11]) TwinStrep tag for affinity purification [S12] 8x His-tag Possible conflict * stop codon
Figure S2 :
S2
Figure S2: Evaluating SARS-CoV-2 spike-protein trimer purity and integrity.(A) Size exclusion chromatography of SARS-CoV-2 spike-protein trimers on Superose 6 columns.Trimer elution peaks at 68-and 13-mL post-injection with Superose 6 Hiload 16/600 pg and Superose 6 Increase 10/300 GL columns, respectively.(B) Representative negative-stain TEM micrographs and 2D classes of SARS-CoV-2 spike-protein trimers show highly homogenous particles in various orientations.
Figure S3 :
S3
Figure S3: Peptide sampling at each NGS across all spike-protein trimers analyzed.(A) Number of unique peptides mapping to each NGS shows that N709, N717 and N1134 are inconsistently sampled, but all other NGS are sufficiently sampled.(B) Bar graph demonstrating N-glycan heterogeneity determined at N1134.The N-glycans present at N1134 are mostly complex as seen in previous studies, though the sampling at this NGS is inconsistent in our study.N-glycosylation states are color-coded.Error bars represent mean-SEM.
Supplementary Table-2: SARS-CoV-2 spike-protein stabilizing mutations.
SARS-CoV-2 spike-protein sequences.Wuhan-Hu-1 2P, 1-1208 (2P -K986P, V987P; Furin CS -R682G, R683S, R685S)MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHVSGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPFLGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPINLVRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNENGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYAWNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIADYNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVEGFNCYFPLQSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLPFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQDVNCTEVPVAIHADQLTPTWRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSPGSASSVASQSIIAYTMSLGAENSVAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAVEQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSFIEDLLFNKVTLADAGFIKQYGDCLGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTITSGWTFGAGAALQIPFAMQMAYRFNGIG6P, 6P-Mut7 VTQNVLYENQKLIANQFNSAIGKIQDSLSSTASALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDI 1-1208 GSASLSRLDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSFPQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVSGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNLNESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGHHHHHHHHSAWSHPQFEKGGGSGGGGSGGSAWSHPQFEK*MuB1.1.621 T95I, Y144T, Y145S,6P-Mut71-1208 GSASins146N, R346K, E484K,N501Y, D614G, P681H,D950NLambdaC.37G75V, T76I, del246-252,6P-Mut71-1208 GSASL452Q, F490S, D614G,T859NNVX-CoV2373--2P1-1273 QQAQVersions Mutations2PK986P, V987P6PF817P, A892P, A899P,A942P, K986P, V987P6P-Mut7 F817P, A892P, A899P,A942P, K986P, V987P;Mut7 -V705C, T883C
Wuhan-Hu-1 6P, 1-1208 (6P -F817P, A892P, A899P, A942P, K986P, V987P; Furin CS -R682G, R683S, R685S)
YAWNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIAD QDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCLGDYNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVEGFNCYF IAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGIGVTQPLQSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFL NVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDILSRPFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQDVNCTEVPVAIHADQLT LDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSFPPTWRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSPGSASSVASQSIIAYTMSLG QSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVSAENSCAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGI GNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNLAVEQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDC NESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGGGSLGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGIG GGGGSGGSAWSHPQFEK*VTQNVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDILSRLDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLM Gamma (P.1) Variant 6P-Mut7, 1-1208 (L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y,SFPQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNT D614G, H655Y, T1027I, V1176F; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C,FVSGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVA T883C; Furin CS -R682G, R683S, R685S)KNLNESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKG MFVFLVLLPLVSSQCVNFTNRTQLPSAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHVGGSGGGGSGGSAWSHPQFEK* SGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNYPFLGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLSEFVFKNIDGYFKIYSKHTPIAlpha (B.1.1.7) Variant 6P-Mut7, 1-1208 (del69-70, del144, N501Y, A570D, D614G, P681H, T716I, NLVRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNS982A, D1118H; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C, T883C; Furin CS ENGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASV-R682G, R683S, R685S) YAWNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGTIADMFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAISG YNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVKGFNCYFTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPFLG PLQSYGFQPTYGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLVYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPINLV PFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNENG PTWRVYSTGSNVFQTRAGCLIGAEYVNNSYECDIPIGAGICASYQTQTNSPGSASSVASQSIIAYTMSLGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYAW AENSCAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGINRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIADYNY AVEQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVEGFNCYFPLQ LGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGIGMFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHV SYGFQPTYGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLPFQ VTQNVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDISGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPF QFGRDIDDTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTPTW LSRLDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAAIKMSECVLGQSKRVDFCGKGYHLMLGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPI RVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSHGSASSVASQSIIAYTMSLGAEN SFPQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTNLVRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYN SCAYSNNSIAIPINFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAVE FVSGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASFVNIQKEIDRLNEVAENGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASV QDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCLGD KNLNESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGYAWNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIAD IAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGIGVTQ GGSGGGGSGGSAWSHPQFEK*YNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVEGFNCYF NVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDILARPLQSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFL QSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTHNTFVS PFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQDVNCTEVPVAIHADQLT LDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSFP Delta (BPTWRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSPGSASSVASQSIIAYTMSLG GNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNLAENSVAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGI NESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGGGSAVEQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDC GGGGSGGSAWSHPQFEK*LGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTITSGWTFGAGPALQIPFPMQMAYRFNGIGVTQNVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDI Beta (B.1.351) Variant 6P-Mut7, 1-1208 (L18F, D80A, D215G, del242-244, K417N, E484K, N501Y, LSRLDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLM D614G, A701V; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C, T883C; Furin CSSFPQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNT -R682G, R683S, R685S)FVSGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVA MFVFLVLLPLVSSQCVNFTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHVKNLNESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKG SGTNGTKRFANPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPFGGSGGGGSGGSAWSHPQFEK* LGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPINLVRGLPQGFSALEPLVDLPIGINITRFQTLHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNENGWuhan-Hu-1 6P-Mut7, 1-1208 (6P -F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C, TITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYAWT883C; Furin CS -R682G, R683S, R685S) NRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGNIADYNYMFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHV KLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVKGFNCYFPLQSGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPF SYGFQPTYGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLPFQLGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPI QFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTPTWNLVRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYN RVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSPGSASSVASQSIIAYTMSLGVENENGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASV SCAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAVE
.1.617.2) Variant 6P, 1-1208 (T19R, G142D, del156-157, R158G, L452R, T478K, D614G, P681R, D950N; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Furin CS -R682G, R683S, R685S)
LNESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGGG Omicron (B.1.1.529) Variant 6P-Mut7, 1-1208 (A67V, del69-70, T95I, G142D, del143-145, del211, MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHVSGGGGSGGSAWSHPQFEK* L212I, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, SGTNVIKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPFQ493R, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, LGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPIMFVFLVLLPLVSSQCVNLRTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHV SGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPF LDVYYHKNNKSWMESGVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPINL VRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNEN GTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYA WNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIADYN EQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCLG QSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVS GGGSGGGGSGGSAWSHPQFEK* NSVAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAV LDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSFP AKNLNESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEK WRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSRGSASSVASQSIIAYTMSLGAE NVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNHNAQALNTLVKQLSSKFGAISSVLNDIFSR TFVSGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEV QQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTPT IAARDLICAQKFKGLTVLPPLLTDEMIAQYTSALLAGTITSGWTFGAGPALQIPFPMQMAYRFNGIGVTQ MSFPQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDN QSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLPF QDKNTQEVFAQVKQIYKTPPIKYFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCLGD ILSRLDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHL YKLPDDFTGCVIAWNSNNLDSKVGGNYNYRYRLFRKSNLKPFERDISTEIYQAGSKPCNGVEGFNCYFPL Delta (B.1.617.2) Variant 6P-Mut7, 1-1208 (T19R, G142D, del156-157, R158G, L452R, T478K, D614G, P681R, D950N; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C, T883C; Furin CS -R682G, R683S, R685S) MFVFLVLLPLVSSQCVNLRTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHV SGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPF LDVYYHKNNKSWMESGVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPINL VRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNEN GTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYA WNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIADYN YKLPDDFTGCVIAWNSNNLDSKVGGNYNYRYRLFRKSNLKPFERDISTEIYQAGSKPCNGVEGFNCYFPL QSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLPF QQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTPT WRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSRGSASSVASQSIIAYTMSLGAE NSCAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAV EQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCLG DIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGIGVT N856K, Q954H, N969K, L981F; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C, NLVRDLPQGFSALEPLVDLPIGINITRFQTLLALHDSSSGWTAGAAAYYVGYLQPRTFLLKYNENGTITD T883C; Furin CS -R682G, R683S, R685S) AVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYAWNRKR MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHVISG ISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIADYNYKLPD TNGTKRFDNPVLPFNDGVYFASIEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPFLD DFTGCVIAWNSNNLDSKVGGNYNYQYRLFRKSNLKPFERDISTEIYQAGSTPCNGVEGFNCYSPLQSYGF HKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPILVREP QPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLPFQQFGR EDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNENG DIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTPTWRVYS TITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFDEVFNATRFASVYAW TGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSPGSASSVASQSIIAYTMSLGAENSCAY NRKRISNCVADYSVLYNLAPFFTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGNIADYNY SNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAVEQDKN KLPDDFTGCVIAWNSNKLDSKVSGNYNYLYRLFRKSNLKPFERDISTEIYQAGNKPCNGVAGFNCYFPLR TQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCLGDIAAR SYSFRPTYGVGHQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLKGTGVLTESNKKFLPFQ DLICAQKFNGLNVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGIGVTQNVLY QFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTPTW ENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDILSRLDPP RVYSTGSNVFQTRAGCLIGAEYVNNSYECDIPIGAGICASYQTQTKSHGSASSVASQSIIAYTMSLGAEN EAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSFPQSAP SCAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLKRALTGIAVE HGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVSGNCD QDKNTQEVFAQVKQIYKTPPIKYFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGDCLGD VVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNLNESL IAARDLICAQKFKGLTVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGIGVTQ IDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGGGSGGGG NVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQDVVNHNAQALNTLVKQLSSKFGAISSVLNDIFSR SGGSAWSHPQFEK* LDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSFP QNVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQNVVNQNAQALNTLVKQLSSNFGAISSVLNDILS RLDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSF PQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFV SGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKN LNESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGGG QSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVS Reference Sequence (Wuhan-Hu-1, 1-1273); UniProt# P0DCT2 GNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNL >QHD43416.1 surface glycoprotein [severe acute respiratory syndrome coronavirus 2] NESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGGGS MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHV GGGGSGGSAWSHPQFEK* SGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPF SGGGGSGGSAWSHPQFEK* Omicron (B.1.1.529) Variant 6P, 1-1208 (A67V, del69-70, T95I, G142D, del143-145, del211, L212I, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493R, LGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPI Mu (B.1.621) Variant 6P-Mut7, 1-1208 (T95I, Y144T, Y145S, ins146N, R346K, E484K, N501Y, D614G, NLVRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYN P681H, D950N; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C, T883C; Furin CS ENGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASV -R682G, R683S, R685S) MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHAIHV YAWNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIAD G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, N856K, SGTNGTKRFDNPVLPFNDGVYFASIEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPF YNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVEGFNCYF Q954H, N969K, L981F; 6P -F817P, A892P, A899P, A942P, K986P, V987P; Furin CS -R682G, LGVTSNHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTP PLQSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFL R683S, R685S) INLVRDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKY PFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQDVNCTEVPVAIHADQLT MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTWFHVISG NENGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATKFAS PTWRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSPRRARSVASQSIIAYTMSLG TNGTKRFDNPVLPFNDGVYFASIEKSNIIRGWIFGTTLDSKTQSLLIVNNATNVVIKVCEFQFCNDPFLD VYAWNRKRISNCVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIA AENSVAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGI HKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPILVREP DYNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPCNGVKGFNCY AVEQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSFIEDLLFNKVTLADAGFIKQYGDC EDLPQGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNENG FPLQSYGFQPTYGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKF LGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTITSGWTFGAGAALQIPFAMQMAYRFNGIG TITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFDEVFNATRFASVYAW LPFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQL VTQNVLYENQKLIANQFNSAIGKIQDSLSSTASALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDI NRKRISNCVADYSVLYNLAPFFTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGNIADYNY TPTWRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQTQTNSHGSASSVASQSIIAYTMSL LSRLDKVEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLM KLPDDFTGCVIAWNSNKLDSKVSGNYNYLYRLFRKSNLKPFERDISTEIYQAGNKPCNGVAGFNCYFPLR GAENSCAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTG SFPQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNT SYSFRPTYGVGHQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVNFNFNGLKGTGVLTESNKKFLPFQ IAVEQDKNTQEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSPIEDLLFNKVTLADAGFIKQYGD FVSGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVA QFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQGVNCTEVPVAIHADQLTPTW CLGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTICSGWTFGAGPALQIPFPMQMAYRFNGI KNLNESLIDLQELGKYEQYIKWPWYIWLGFIAGLIAIVMVTIMLCCMTSCCSCLKGCCSCGSCCKFDEDD RVYSTGSNVFQTRAGCLIGAEYVNNSYECDIPIGAGICASYQTQTKSHGSASSVASQSIIAYTMSLGAEN SVAYSNNSIAIPTNFTISVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLKRALTGIAVE GVTQNVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQNVVNQNAQALNTLVKQLSSNFGAISSVLND SEPVLKGVKLHYT*DIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTITSGWTFGAGPALQIPFPMQMAYRFNGIGVT GNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNLQNVLYENQKLIANQFNSAIGKIQDSLSSTPSALGKLQNVVNQNAQALNTLVKQLSSNFGAISSVLNDILS NESLIDLQELGKYEQGSGYIPEAPRDGQAYVRKDGEWVLLSTFLGRSLEVLFQGPGSAWSHPQFEKGGGS Lambda (C.37) Variant 6P Mut7, 1-1208 (G75V, T76I, del246-252, L452Q, F490S, D614G, T859N; 6P -GGGGSGGSAWSHPQFEK* F817P, A892P, A899P, A942P, K986P, V987P; Mut7 -V705C, T883C; Furin CS -R682G, R683S, RLDPPEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECVLGQSKRVDFCGKGYHLMSF PQSAPHGVVFLHVTYVPAQEKNFTTAPAICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFV R685S)SGNCDVVIGIVNNTVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKN
Site-specific glycan analysis of the SARS-CoV-2 spike. Y Watanabe, J D Allen, D Wrapp, J S Mclellan, M Crispin, 10.1126/science.abb998332366695PMC7199903Science. 36965012020 Jul 17. 2020 May 4
Glycosylation and Serological Reactivity of an Expression-enhanced SARS-CoV-2 Viral Spike Mimetic. H Chawla, S E Jossi, S E Faustini, F Samsudin, J D Allen, Y Watanabe, M L Newby, E Marcial-Juárez, R E Lamerton, J S Mclellan, P J Bond, A G Richter, A F Cunningham, M Crispin, 10.1016/j.jmb.2021.16733234717971PMC8550889J Mol Biol. 43421673322022 Jan 30. 2021 Oct 27
Variations within the Glycan Shield of SARS-CoV-2 Impact Viral Spike Dynamics. M L Newby, C A Fogarty, J D Allen, J Butler, E Fadda, M Crispin, 10.1016/j.jmb.2022.16792836565991PMC9769069J Mol Biol. 43541679282023 Feb 28. 2022 Dec 21
Site specific N-and O-glycosylation mapping of the spike proteins of SARS-CoV-2 variants of concern. Sci Rep. A Shajahan, L E Pepi, B Kumar, N B Murray, P Azadi, 10.1038/s41598-023-33088-037344512PMC102849062023 Jun 211310053
Deducing the N-and O-glycosylation profile of the spike protein of novel coronavirus SARS-CoV-2. Glycobiology. A Shajahan, N T Supekar, A S Gleinich, P Azadi, 10.1093/glycob/cwaa04232363391PMC72391832020 Dec 930
N-glycosylation profiles of the SARS-CoV-2 spike D614G mutant and its ancestral protein characterized by advanced mass spectrometry. Sci Rep. D Wang, B Zhou, T R Keppel, M Solano, J Baudys, J Goldstein, M G Finn, X Fan, A P Chapman, J L Bundy, A R Woolfitt, S H Osman, J L Pirkle, D E Wentworth, J R Barr, 10.1038/s41598-021-02904-w34876606PMC86516362021 Dec 71123561
Immunogenicity and structures of a rationally designed prefusion MERS-CoV spike antigen. J Pallesen, N Wang, K S Corbett, D Wrapp, R N Kirchdoerfer, H L Turner, C A Cottrell, M M Becker, L Wang, W Shi, W P Kong, Andres El Kettenbach, A N Denison, M R Chappell, J D Graham, B S Ward, A B Mclellan, J S , 10.1073/pnas.170730411428807998PMC5584442Proc Natl Acad Sci. 114352017 Aug 29. 2017 Aug 14
Structural analysis of full-length SARS-CoV-2 spike protein from an advanced vaccine candidate. S Bangaru, G Ozorowski, H L Turner, A Antanasijevic, D Huang, X Wang, J L Torres, J K Diedrich, J H Tian, A D Portnoff, N Patel, M J Massare, Yates Jr 3rd, D Nemazee, J C Paulson, G Glenn, G Smith, A B Ward, 10.1126/science.abe150233082295PMC7857404Science. 37065202020 Nov 27. 2020 Oct 20
Structure-based design of prefusion-stabilized SARS-CoV-2 spikes. C L Hsieh, J A Goldsmith, J M Schaub, A M Divenere, H C Kuo, K Javanmardi, K C Le, D Wrapp, A G Lee, Y Liu, C W Chou, P O Byrne, C K Hjorth, N V Johnson, J Ludes-Meyers, A W Nguyen, J Park, N Wang, D Amengor, J J Lavinder, G C Ippolito, J A Maynard, I J Finkelstein, J S Mclellan, 10.1126/science.abd082632703906PMC7402631Science. 36965102020 Sep 18. 2020 Jul 23
the natural trimerization domain of T4 fibritin, dissociates into a monomeric A-state form containing a stable beta-hairpin: atomic details of trimer dissociation and local beta-hairpin stability from residual dipolar couplings. S Meier, S Güthe, T Kiefhaber, Grzesiek S Foldon, 10.1016/j.jmb.2004.09.07915544812J Mol Biol. 34442004 Dec 3
Substrate requirements of human rhinovirus 3C protease for peptide cleavage in vitro. M G Cordingley, P L Callahan, V V Sardana, V M Garsky, R J Colonno, 2160953J Biol Chem. 265161990 Jun 5
Development of the Twin-Strep-tag® and its application for purification of recombinant proteins from cell culture supernatants. T G Schmidt, L Batz, L Bonet, U Carl, G Holzapfel, K Kiem, K Matulewicz, D Niermeier, I Schuchardt, K Stanar, 10.1016/j.pep.2013.08.02124012791Protein Expr Purif. 9212013 Nov. 2013 Sep 6
| [
-0.21455137431621552,
-0.06724831461906433,
-0.16026407480239868,
-0.09516716748476028,
0.06323537230491638,
-0.022600583732128143,
-0.08235566318035126,
0.17013418674468994,
0.04430652782320976,
0.03201261907815933,
0.13835439085960388,
0.08171653002500534,
-0.13636691868305206,
0.0479220... |
Postprandial sleep in short-sleeping Mexican cavefish
Kathryn Gallman
Department of Biology
Texas A&M University
77840College StationTX
Aakriti Rastogi
Department of Biology
Texas A&M University
77840College StationTX
Owen North
Department of Biology
Texas A&M University
77840College StationTX
Morgan O'gorman
Department of Biology
Texas A&M University
77840College StationTX
Pierce Hutton
Department of Biology
Texas A&M University
77840College StationTX
Evan Lloyd
Department of Biology
Texas A&M University
77840College StationTX
Wes Warren
Department of Genomics
University of Missouri
65201ColumbiaMO
Johanna E Kowalko
Department of Biological Sciences
Lehigh University
18015BethlehemPA
Erik R Duboue
Florida Atlantic University
33458JupiterFL
Nicolas Rohner
Stowers Institute for Medical Research
64110Kansas CityMO
Alex C Keene
Department of Biology
Texas A&M University
77840College StationTX
Postprandial sleep in short-sleeping Mexican cavefish
0BC8F28AE58DC0D644771A585783494410.1101/2024.07.03.602003
Interaction between sleep and feeding behaviors are critical for adaptive fitness.Diverse species suppress sleep when food is scarce to increase the time spent foraging.Post-prandial sleep, an increase in sleep time following a feeding event, has been documented in vertebrate and invertebrate animals.While interactions between sleep and feeding appear to be highly conserved, the evolution of postprandial sleep in response to changes in food availability remains poorly understood.Multiple populations of the Mexican cavefish, Astyanax mexicanus, have independently evolved sleep loss and increased food consumption compared to surface-dwelling fish of the same species, providing the opportunity to investigate the evolution of interactions between sleep and feeding.Here, we investigate effects of feeding on sleep in larval and adult surface fish, and two parallelly evolved cave populations of A. mexicanus.Larval surface and cave populations of A. mexicanus increase sleep immediately following a meal, providing the first evidence of postprandial sleep in a fish model.The amount of sleep was not correlated to meal size and occurred independently of feeding time.In contrast to larvae, postprandial sleep was not detected in adult surface or cavefish, that can survive for months without food.Together, these findings reveal that postprandial sleep is present in multiple short-sleeping populations of cavefish, suggesting sleep-feeding interactions are retained despite the evolution of sleep loss.These findings raise the possibility that postprandial sleep is critical for energy conservation and survival in larvae that are highly sensitive to food deprivation.
Introduction
Sleep and metabolic regulation are highly variable throughout the animal kingdom (Lesku et al. 2006;Joiner 2016;Keene and Duboue 2018;Seebacher 2018).This variability is reflected by the diversity of food availability and foraging strategy, which potently impact the duration and timing of sleep.There is an interaction between sleep and feeding, regardless of life history strategy, that is critical for organismal survival, and therefore, under selection (Capellini et al. 2008;Yurgel et al. 2014;Slocumb et al. 2015;Aulsebrook et al. 2016;Brown et al. 2019).While both of these behavioral processes have been studied in detail, much less is known about interactions between sleep and feeding, particularly in the context of evolution.
In many species, sleep deprivation results in increased food intake, while prolonged periods of food deprivation lead to a reduction in metabolic rate and suppression of sleep (Keene et al. 2010;Arble et al. 2015;Stahl et al. 2017;Regalado et al. 2017;Goldstein et al. 2018).Conversely, animals ranging from the nematode, C. elegans, to humans, increase sleep immediately following a meal, revealing an acute effect of dietary nutrients on sleep regulation (Stahl et al. 1983;Murphy et al. 2016;Makino et al. 2021).Defining how evolution has shaped interactions between sleep, metabolic regulation, and feeding is critical to determine the functions of these traits.
The rapidly increasing number of organisms used to study sleep provides new opportunities to study interactions between sleep and metabolism (McNamara et al. 2009;Anafi et al. 2019).Fish have become a model to study the biological basis of sleep regulation (Chiu and Prober 2013; Levitas-Djerbi and Appelbaum 2017; Keene and Appelbaum 2019).Growing evidence suggests the genetic and functional basis of sleep is conserved across multiple fish species (Chiu and Prober 2013;Levitas-Djerbi and Appelbaum 2017;Keene and Appelbaum 2019).Further, the small size and amenability to genetic manipulation of these fish allows for high-throughput genetic and pharmacological screens to identify novel regulators of sleep (Rihel et al. 2010;Chiu et al. 2016;Kroll et al. 2021).Furthermore, at larval stages, many fish models are transparent, allowing for mapping of sleep and feeding circuits across the entire brain (Semmelhack et al. 2014;Leung et al. 2019;Wee et al. 2019;Förster et al. 2020).Therefore, zebrafish and other fish models are exceptionally well positioned to examine interactions between sleep and feeding.
The Mexican tetra, A. mexicanus exist as river-dwelling surface fish and at least 30 blind populations of cavefish, which have evolved in nutrient-limited environments, providing the opportunity to examine sleep after fasting and postprandial sleep in an evolutionary context (Jeffery 2009;Gross 2012;McGaugh et al. 2020).Multiple cavefish populations have evolved behavioral and physiological differences relative to surface fish including sleep loss, reduced metabolic rate, and increased feeding (Duboué et al. 2011;Moran et al. 2014;Aspiras et al. 2015;Yoshizawa 2015;Volkoff 2016).Long-term starvation has opposing effects on sleep between the surface and cave populations.Starved surface fish suppress sleep, while starved cavefish increase sleep, suggesting that the evolutionary factors shaping the sleep-feeding interaction differ between populations (Jaggard et al. 2018).However, sleep-feeding interactions are poorly understood, and postprandial sleep has to our knowledge not been identified in any fish model to date.Examining the effects of feeding state on sleep in surface and cave populations of A. mexicanus has the potential to identify whether these behaviors evolved through shared genetic mechanisms and to provide insight into how sleep-feeding interactions are influenced by adaptation to a nutrient-poor cave environment.
Larval A. mexicanus provide a particularly tractable model for examining the effects of feeding on sleep regulation.Multiple populations of cavefish larvae have converged on sleep loss similar to adults (Duboué et al. 2011;Yoshizawa et al. 2015).However, while adult fish can live for months without food, larval fish live for only a matter of days (Salin et al. 2010;Medley et al. 2022;Pozo-Morales et al. 2024).Therefore, interactions between feeding and other behaviors may be particularly important for the survival of larvae and young juvenile fish.Feeding larval fish Artemia is readily quantifiable and large numbers of larval fish can be tested without the need to grow fish to adulthood (Espinasa et al. 2014(Espinasa et al. , 2017;;Lloyd et al. 2018).The experimental amenability of larval fish allows for efficient characterization of sleep-feeding interactions across different behavioral and genetic contexts, providing a model to investigate the evolutionary relationship between these processes.
Here, we characterize the effects of starvation and acute feeding on sleep in surface fish and multiple A. mexicanus cavefish populations.We identify multiple sleep-feeding interactions in A. mexicanus, including the presence of post-prandial sleep in multiple, parallelly evolved cavefish populations.Feeding promotes sleep, independent of time-of-day, revealing the presence of postprandial sleep in both surface and cavefish.Together, these findings reveal interactions between feeding and sleep and provide a model system to examine how these interactions evolved.
Results
To investigate the effects of feeding on sleep, we compared sleep in different populations of cavefish immediately following a meal.Briefly, fish were fed a meal, and baseline sleep and activity were measured for 24 hours prior to sleep and feeding measurements.At Zeitgeber Time (ZT) 0 on the second day, fish were fed 70 Artemia over two hours, followed by a four-hour recording of sleep (Fig 1A).In agreement with previous findings, baseline sleep was lower in both Pachón and Tinaja cavefish compared to surface fish (Fig 1B;Duboué et al. 2011a;Jaggard et al. 2020;O'Gorman et al. 2021a).When sleep was measured following a two-hour feeding period, surface fish slept significantly more than cavefish from both populations (Fig 1C).Consistent with previous findings, quantification of Artemia consumed during the two-hour feeding window revealed significantly greater consumption in Tinaja fish, but not Pachón cavefish, compared to surface fish (Aspiras et al. 2015;Alié et al. 2018)(Fig 1D).Taken together, these findings reveal difference in sleep and feeding behavior of larval A. mexicanus populations.
It is possible that sleep is elevated across A. mexicanus populations from ZT2-ZT6 due to postprandial sleep or light-regulated rest-activity rhythms.To differentiate between these possibilities, we compared sleep following meals prior to ZT2, ZT6, and ZT10.Feeding time was limited to half an hour to provide additional resolution for postprandial sleep (Fig 2A -C).Across feeding time courses, surface fish slept more than cavefish populations (Fig 2D-F), supporting the notion that surface fish sleep more than cavefish independent of feeding treatment.To measure for postprandial sleep, we compared sleep duration during the four hours following feeding to the remaining hours of daytime (excluding the time for the feeding assay) to determine the percent change in sleep post feeding.Sleep was increased following the meal across all three timepoints, for surface fish and both cavefish populations (Fig 2G-I).Strikingly, for all timepoints tested, there was a significant increase in the amount of postprandial sleep, measured by the increase over the baseline sleep (Fig 2G -I).Variation in the degree of postprandial sleep increase across populations were dependent of feeding time.There were no differences in the percent increase in postprandial sleep between populations fed prior to ZT2, but Surface fish had a significantly greater increase in postprandial sleep than Tinaja cavefish fed prior to ZT6, and Pachón fish had a significantly greater increase in postprandial sleep than either surface and Tinaja cavefish fed prior to ZT10.Similarly, both surface and Pachón cavefish, but not Tinaja cavefish, experienced a significantly greater increase in postprandial sleep prior to ZT10 than for the timepoints earlier in the day.Therefore, while postprandial sleep occurs across A. mexicanus populations, the degree to which sleep is increased in each population is dependent on the time of day that feeding occurs.Taken together, these findings reveal the presence of postprandial sleep in surface and cave populations of A. mexicanus.
It is possible that meal size, or its caloric value, contributes to the duration of postprandial sleep.
To determine whether the amount of postprandial sleep is related to meal size, we examined the correlation between the number of Artemia consumed and the duration of sleep in the four hours following the meal.For surface fish fed prior to ZT2, there was a significant positive correlation between meal size and post prandial sleep, however there was no significant correlation for surface fish fed prior to ZT6 and ZT10 (Fig 3A-C).For both Pachón (Fig 3D -F) and Tinaja (Fig 3G-H) cavefish, there was no correlation between Artemia consumed and postprandial sleep.
Therefore, postprandial sleep is largely driven by the presence of a meal and does not appear to be directly linked to meal size.
Postprandial sleep may provide a mechanism for conserving energy immediately following successful foraging.Conversely, many animals suppress sleep under food-deprived conditions, presumably to forage for food (Macfadyen et al. 1973;Danguir and Nicolaidis 1979;Keene et al. 2010;Goldstein et al. 2018).Larval A. mexicanus survive for only a few days without food, raising the possibility that sleep will be acutely impacted by feeding state.To directly examine the effects of feeding state on sleep, we compared sleep in 20 days post fertilization (dpf) fish that were fed from ZT0-ZT2 to unfed fish that had been starved for the previous 24 hours (Fig 4A -C).Surface fish and both populations of cavefish slept significantly more during the four hours following feeding than unfed controls (Fig 4D-F).To further examine the effects of feeding on sleep, we analyzed the activity patterns of fed and unfed fish using a Markov model that predicts the sleep and wake propensity, both indicators of sleep drive (Wiggin et al. 2020).Across all three populations, fed fish had a significantly greater sleep propensity P(Doze) and a significantly lower waking propensity P(Wake) than unfed fish, suggesting that sleep drive is increased following feeding (Fig 4G-I).Together, these findings reveal that both surface and cavefish suppress sleep when starved, and that starvation-induced sleep suppression is intact in short-sleeping cavefish.
Adult A. mexicanus live months without food and are thought to be highly adapted to survive periods of starvation (Cobham and Rohner 2024).Previously, we have shown that surface fish suppress sleep during periods of prolonged starvation, while cavefish increase sleep (Jaggard et al. 2018).To determine whether differences in sleep response extend to acute behavior following meals, we examined postprandial sleep in adult surface and cavefish.Fish were starved for five days prior to recording to synchronize meal patterns and then fed a blood-worm meal at ZT6.In agreement with previous findings (Jaggard et al. 2018), control surface fish that were not fed slept significantly more than Pachón and Tinaja cavefish (Fig 5 A, I).Similarly, in fish fed at ZT6, surface fish slept significantly more than Tinaja and Pachòn cavefish (Fig 5B , J).To examine whether postprandial sleep is present in adult A. mexicanus, we compared sleep during the four hours following feeding to unfed counterparts (Fig 5C -E).Within this four-hour duration, there were no significant differences in sleep duration (Fig 5F -H) or sleep propensity (Fig 5K -M) between fed and unfed fish across the three A. mexicanus populations.Therefore, there is no evident postprandial sleep for adults under the conditions tested, supporting the notion that post prandial sleep is less robust at a life stage when fish are more starvation resistant.
Discussion
To date, five populations of A. mexicanus cavefish have been studied under laboratory conditions, all of which have significantly reduced sleep compared to surface fish populations (Yoshizawa et al. 2015).These findings have led to the speculation that reduced sleep is adaptive in the foodpoor cave environment because it provides more time to forage (Keene et al. 2015;Keene and Duboue 2018).However, nearly all studies to date have examined sleep in fed animals, using daily averages.Therefore, little is known about how sleep differs between populations under natural conditions and in response to feeding.Here, we describe interactions between sleep and feeding behavior in surface fish and two different populations of cavefish.All three populations sleep more following feeding than under food-deprived conditions, revealing that feeding is required for baseline sleep.Furthermore, all three populations sleep more in the period following a meal as larvae, but not as adults.These findings suggest that despite robust sleep loss across cavefish populations, sleep-feeding interactions have remained intact.
Numerous neural mechanisms associated with sleep loss in cavefish have been identified including elevated levels of the wake-promoting neuropeptide Hypocretin (HCRT), changes in wake-promoting catecholamine systems (Duboué et al. 2012;Bilandzija et al. 2013;Gallman et al. 2019) providing candidate regulators of postprandial sleep.Similarly, feeding is increased in multiple populations of adult A. mexicanus (Aspiras et al. 2015).In agreement with previous findings, we find that feeding is elevated in 20 days post fertilization juvenile cavefish from the Tinaja, but not Pachón population (O'Gorman et al. 2021).In adults, differences in feeding are at least partially attributable to polymorphisms in the GPCR Melanocortin 4 receptor (Mc4r) which is associated with obesity in humans and animal models (Aspiras et al. 2015).While there is little evidence that MC4R directly regulates sleep, it is thought to contribute to obesity-induced sleep apnea that in turn regulates sleep (Larkin et al. 2010;Pillai et al. 2014).Our findings that postprandial sleep is intact in Tinaja cavefish suggests that Mc4r, and other genes involved in feeding, are likely dispensable for sleep feeding interactions.There are also numerous genes that have been identified to regulate sleep or feeding in fish models that are potential regulators of sleepmetabolism interactions.For example, the orexigenic neuropeptides Neuropetide Y (Npy) and Hcrt both induce wakefulness, providing a potential molecular mechanism for feeding-dependent modulation of sleep (Appelbaum et al. 2009;Penney and Volkoff 2014;Singh et al. 2015Singh et al. , 2017;;Jaggard et al. 2018).Future functional analysis is required to define whether these candidate genes regulate interactions between sleep and feeding.
In A. mexicanus, rhythmic transcription is significantly diminished under dark-dark conditions, and cavefish have elevated levels of light-inducible genes (Beale et al. 2013).The circadian clock plays a critical role in the timing of both sleep and feeding, raising the possibility that the circadian clock may be critical for sleep-feeding interactions.Transcriptome-wide analysis in larvae, reveals a loss of rhythmic gene expression across all cave populations tested (Mack et al. 2021) Therefore, because identified postprandial sleep in all of the populations tested across three different timepoints during the day, postprandial sleep may be independent of time-of-day and may not require a functioning circadian clock.
A. mexicanus larvae, like zebrafish, can subsist on a variety of foods including paramecium, rotifers, and fish feed that differ in micronutrients.In this study, A. mexicanus larvae were fed a standard diet of Artemia.Artemia is comprised of macronutrients that include diverse fatty acids, proteins, and carbohydrates.Analysis suggests that Artemia is ~40-60% protein, raising the possibility that consumption of dietary protein may impact sleep (de Clercq et al. 2005).In Drosophila, dietary protein promotes post-prandial sleep, while a loss of dietary protein disrupts sleep depth (Murphy et al. 2016;Brown et al. 2020;Titos et al., 2023).Therefore, it is possible that changes in protein detection, or its downstream targets, regulate the physiology of sleep circuits that are responsible for the different effects of feeding on sleep between Pachón and Tinaja cavefish.Understanding the effects of different diets on sleep, and how individual macronutrients regulate sleep across populations could reveal evolved differences in sleepfeeding interactions across different A. mexicanus populations.
The identification of postprandial sleep in cavefish provides an avenue for future studies examining the genetic basis of this behavior.Mapping genetic loci associated with trait variation has been used to identify candidate regulators of many morphological and behavioral traits, including regulators of sleep, activity, feeding posture, and metabolism (Kowalko et al. 2013;Yoshizawa et al. 2015;Carlson et al. 2018;Riddle et al. 2021).Further, population genetic approaches have identified genome-wide markers of selection across multiple cave populations, and this genetic variation may provide insight into genes impacting sleep-feeding interactions (Herman et al. 2018;Warren et al. 2021;Moran et al. 2022).Genes with signatures of selection that have previously been implicated in sleep or feeding could provide candidate regulators of postprandial sleep.In A. mexicanus, like zebrafish, CRISPR-based gene editing has been used to functionally validate genes identified through genomics approaches and could be applied to the investigation of postprandial sleep (Klaassen et al. 2018;Kroll et al. 2021).Genetic studies will require the use of CRISPR for forward genetic screens, or the identification of A. mexicanus with diminished or highly variable post-prandial sleep that can be used for genetic mapping studies.
In conclusion, these studies identify postprandial sleep in A. mexicanus and suggest it is under independent genetic regulation from total sleep duration and meal size in surface fish and two parallely evolved populations of cavefish.These studies lay the groundwork for future analysis that apply currently available population genetics, neural anatomical, and genetic screening toolsets in A. mexicanus to examine the integration of feeding and sleep regulation
Materials and Methods
Methods
Husbandry
Throughout this study, we followed previously described standard animal husbandry and breeding for A. mexicanus (Borowsky 2008a).All fish were housed under standard temperature (23°C for adults, 25°C for embryos and larvae) and lighting conditions (14:10 hr light:dark cycle).Adult fish were bred by increasing water temperature to 27±1°C and feeding a high-calorie diet that includes thawed frozen bloodworms three times per day (Elipot et al. 2014) .Larvae were fed brine shrimp (Artemia nauplii) ad libitum from 6 -20 days post-fertilization (dpf; Borowsky 2008b).Embryos and larvae were held in small glass bowls until behavioral testing.All procedures in this study were approved under the Florida Atlantic University and Texas A&M University IACUC.
Sleep behavior
These experiments focused on three distinct A. mexicanus morphotypes: the sighted, surfacedwelling Río Choy, and two blind, cave-dwelling populations, Pachón and Tinaja.We quantified sleep behavior in these fish using previously described methods (Jaggard et al. 2019a) and baseline sleep data (O'Gorman et al. 2021).Briefly, we used Ethovision XT 17.0 software (Noldus Information Technology, Wageningen, the Netherlands) to track locomotor behavior.Raw locomotor behavior was used to calculate sleep behavior parameters using a custom Perl script (Jaggard et al. 2019b).We operationally define sleep as 60 seconds or more of immobility given that previous studies show both surface and Pachón cavefish exhibit increased arousal thresholds after this period (Jaggard et al. 2019b).We defined immobility as a velocity below 6 mm/sec for larval fish and a velocity below 4 cm/sec for adult fish.All recordings were performed at 23 °C under a 14:10 hour light/dark cycle.
Larval behavior recordings
All larval used to quantify sleep behavior were 20 dpf.Fish were fed and then acclimated individually in 24-well plates for at least 15 hours prior to behavior recordings.Recordings began at ZT0 and lasted for 24 hours, with interruptions for feeding at specific time points.The 24-well plates were placed on light boxes made from white acrylic housing infrared (IR) lights (Figure 1A).
Basler ace acA1300-200um Monochrome USB 3.0 Cameras with mounted IR filters were mounted above the well plates and recordings were taken using Pylon Viewer software.
The effects of feeding on sleep were tested throughout the light cycle at time points prior to ZT0, ZT2, ZT6, and ZT10.Each 24-well plate was either not fed as a control or fed at a single time point.We conducted two separate feeding experiments.In the first experiment, larvae were fed for 10 mins immediately before a 24-hour recording beginning at ZT0.This 24-hour recording was followed by a 2-hour feeding behavior assay (described below) and then another behavior recording for 4 hours from ZT2-ZT6 (Fig 1).In the second experiment, we recorded behavior for 24 hours around a 45-minute window for feeding prior to either ZT2, ZT6, or ZT10.
Larval feeding behavior assay
To quantify the relationship between the amount of food consumption and post-prandial sleep duration, we performed feeding assays that allowed us to count the number of Artemia over a given time.The duration of the feeding assay was 2 hours for the first experiment, starting at ZT0 following 24 hours of recording.The duration of the feeding assay was 30 minutes for the second experiment, starting prior to ZT2, ZT6, or ZT10.For the 2-hour feeding assay, fish were given exactly 70 Artemia, for the 30 minute feeding assay, Artemia were provided ad libitum.We filled a new 24-well plate with Artemia hatched within 24 hours and recorded for at least one minute prior to transferring the larval fish from the recording well plate to this new feeding well plate.At the end of the recording duration, fish were removed from the feeding assay, placed back into the original 24-well recording plate with clean water and returned to the behavior recording.We used FIJI (Schindelin et al. 2012) to count the number of Artemia both before the fish were added to the wells and at the end of the feeding assay.Subtraction of the former from the latter allowed us to determine the amount of Artemia eaten over the duration of the feeding assay.
Adult behavior recordings
Adult fish used for behavior recordings were approximately 1 year old with an equal number of males and females per treatment.Food was withheld for 5 days prior to recording.Fish were placed in individual glass tanks of approximately 30 x 17 cm in a 2 x 2 grid in front of an IR light board and left to acclimate for at least 24 hours.Recordings began at ZT0 and lasted 24 hours.
In the top two tanks, 4 oz of thawed, frozen blood worms were added at ZT5.5 and any uneaten worms were removed after 30 minutes at ZT6.The fish in the bottom two tanks were not fed as a control.
Analysis
Warren, W. C., T. E. Boggs, R. Borowsky, B. M. Carlson, E. Ferrufino et al., A) 20 dpf fish were briefly fed prior to 24 h behavioral sleep recordings.At ZT0 the following day, fish were assayed for feeding behavior until ZT2, immediately after which we recorded sleep behaviors between ZT2 and 6.B) Sleep profiles of wild type surface, Pachón, and Tinaja fish taken over the experiment.Lines and error bars represent the mean ± SD.C) Cross-population comparison of total sleep duration immediately following the feeding experiment.Cavefish slept significantly less than surface fish (ANOVA: F2, 34 = 8.123, p = 0.0013; Tukey's HSD for surface-Pachón, p = 0.0202, p = 0.0024; Tukey's HSD for surface-Tinaja, p = 0.0024).D) Cross-population comparison of the number of Artemia eaten during the two-h feeding experiment.Tinaja ate significantly more than surface fish (ANOVA: F2, 76 = 3.91, p = 0.0242; Tukey's HSD for surface-Tinaja, p = 0.0178).
no significant difference across populations in the percentage of increase in postprandial sleep (Anova: F2, 104 = 3.36, p = 0.0417).H) Percent change of postprandial sleep after ZT6 feeding window.Surface: t = 13.65,df = 47, p < 0.0001; Pachón: t = 2.67, df = 23, p = 0.0137; Tinaja: t = 2.480, df = 26, p = 0.0200.There was no significant different in the percentage of increase in postprandial sleep between surface and Pachón cavefish, but surface fish had a significantly greater increase in sleep than Tinaja cavefish (ANOVA: F2, 96 = 5.758, p = 0.0072; Tukey's HSD for surface-Tinaja, p = 0.0101).I) Percent change of postprandial sleep after ZT10 feeding window.Surface: t = 8.619, df = 52, p < 0.0001; Pachón: t = 10.27,df = 43, p < 0.0001; Tinaja: t = 3.636, df = 16, p = 0.0022.Pachón cavefish had a significantly greater percent increase in postprandial sleep than both surface and Tinaja cavefish (ANOVA: F2, 111 = 4.727, p = 0.0107; Tukey's HSD for surface-Pachón, p = 0.0298; Tukey's HSD for Pachón-Tinaja, p = 0.0275).For surface fish and Pachón cavefish, the percentage of increase in postprandial sleep was significantly greater after a ZT10 feeding window than at any other timepoint (Surface Anova: F2, 144 = 13.84,p < 0.0001; Pachón Anova: F2, 197 = 19.56,p < 0.0001).There were no other significant differences in the percent increase for postprandial sleep between timepoints or for Tinaja cavefish (Tinaja Anova: F2, 70 = 3.978, p = 0.0231).
Figure 3 :
3
Figure 3: Postprandial sleep in larval Astyanax is not dependent on the amount of food consumed, regardless of the time of day that feeding occurs.Correlation of amount of Artemia nauplii consumed with sleep duration in the four hours following feeding with a simple linear regression for surface (A-C), Pachón (D-F), and Tinaja (G-I).A, D, G) Larvae were fed prior to ZT2.B, E, H) Larvae were fed prior to ZT6.C, F, I) Larvae were fed prior to ZT10.
Figure 5 :
5
Figure 5: Adult Astyanax do not display post prandial sleep behavior.A, B) Sleep profiles of adult Surface, Pachón, and Tinaja, in minutes per hour.Lines and error bars represent the mean ± SD.A, I) Fish were not fed over the course of the day.B, J) Fish were provided food from ZT5.5 (indicated by the arrow and dotted black line in B) to ZT6.I, J) Cross-population comparison of total sleep duration in hours over the 24-hour day.Letters represent significant differences.I) Total sleep duration in 24 hours was significantly different between unfed surface and cave populations of A. mexicanus ((ANOVA: F2, 28 = 15.5, p < 0.0001; Tukey's HSD for Surface-Pachón, p < 0.0001 and Surface-Tinaja, p = 0.0015).J) Total sleep duration in was significantly different between fed surface and cave populations of A. mexicanus ((ANOVA: F2, 25 = 15.04,p < 0.0001; Tukey's HSD for Surface-Pachón, p < 0.0001 and Surface-Tinaja, p = 0.0008).C-E) Four-hour sleep profiles comparing the sleep of fed (orange) and unfed (black) individuals in each population.Lines and error bars represent the mean ± SEM.F-H) There are no significant differences in sleep during the four hours following feeding, regardless of the population.F) Surface: Mann-Whitney U = 88, nfed = 12, nunfed = 15, p = 0.9317.G) Pachon: Mann-Whitney U = 31.5,nfed = 8, nunfed = 8, p > 0.9999.H) Tinaja: Mann-Whitney U = 22.5, nfed = 8, nunfed = 8, p > 0.2.K-M) There are no significant differences in activity state transitions between fed and unfed fish.K) Surface: P(Wake) t = 0.271, df = 22, p = 0.7888; P(Doze) t = 2.041, df = 22, p = 0.054.L) Pachon: Mann-Whitney U = 24, nfed = 8, nunfed = 8; P(Wake) p = 0.4667; P(Doze) p = 0.4667.M) Tinaja: Mann-Whitney U = 23, nfed = 8, nunfed = 8; P(Wake) p = 0.5714; P(Doze) p = 0.1319).Horizontal lines represent quartiles.
Sleep, feeding, and post-prandial sleep behaviors across three populations of wild- type Astyanax mexicanus.
2021 A chromosomelevel genome of Astyanax mexicanus surface fish for comparing population-specific genetic differences contributing to trait evolution.Nat Commun 12: 1447.Wee, C. L., E. Y. Song, R. E. Johnson, D. Ailani, O. Randlett et al., 2019 A bidirectional network for appetite control in larval zebrafish.Elife 8:.Wiggin, T. D., P. R. Goodwin, N. C. Donelson, C. Liu, K. Trinh et al., 2020 Covert sleep-related biological processes are revealed by probabilistic analysis in Drosophila.Proc Natl Acad Sci U S A 117: 10024-10034.Yoshizawa, M., 2015 Behaviors of cavefish offer insight into developmental evolution.Mol Reprod Dev 82: 268-280.Yoshizawa, M., B. G. Robinson, E. R. Duboué, P. Masek, J. B. J. Jaggard et al., 2015 Distinct genetic architecture underlies the emergence of sleep loss and prey-seeking behavior in the Mexican cavefish.BMC Biol 20: 15.Yurgel, M., P. Masek, J. R. DiAngelo, and A. Keene, 2014 Genetic dissection of sleep-metabolism interactions in the fruit fly.J Comp Physiol A Neuroethol Sens Neural Behav Physiol.epub ahead:
Figures Figure 1.
Acknowledgements: This work was supported by NIH Grants NIH 1R01GM127872 to SEM, NR, and ACK; R24 OD030214 to WW, NR and ACK; R21 NS122166 to ACK and JEK; 1DP2AG071466-01 to NR; NSF Grant NSF grant IOS 2202359 to JEK and SEM.The authors are grateful for technical assistance from Kaya Harper and Lawaal Agboola.Statistical analyses were performed in GraphPad Prism (version # 9.5.0) and R (version 4.0.4).When assumptions of normality and equal variances were met, we used parametric t-tests, ANOVA, and Pearson's r tests, otherwise we used non-parametric Mann-Whitney U, Kruskal-Wallis, and Spearman's ρ tests.Following a significant ANOVA or Kruskal-Wallis test, pairwise comparisons were made using Tukey's HSD or Dunn's test, respectively.To quantify the percent change in sleep duration during the 4 hours following feeding, we determined the proportion of total daylight sleep to total daylight recording time as well as the proportion of sleep to the 4 hour post prandial recording period.We then calculated percent change as the proportion of post prandial sleep minus the proportion of total daylight sleep divided by the proportion of total daylight sleep.Finally, to test whether the amount of Artemia consumed was related to post-prandial sleep duration, we analyzed the goodness of fit from a linear regression.
Developmental evolution of the forebrain in cavefish: from natural variations in neuropeptides to behavior. A Alié, L Devos, J Torres-Paz, L Prunier, F Boulet, 2018Elife
Exploring phylogeny to find the function of sleep. R C Anafi, M S Kayser, D M Raizen, Nat Rev Neurosci. 202019
Sleep-wake regulation and hypocretin-melatonin interaction in zebrafish. L Appelbaum, G X Wang, G S Maro, R Mori, A Tovin, Proc Natl Acad Sci U S A. 1062009
D M D M Arble, J Bass, C D C D Behn, M P M P Butler, E Challet, Impact of Sleep and Circadian Disruption on Energy Balance and Diabetes : A Summary of Workshop Discussions. 201538
Melanocortin 4 receptor mutations contribute to the adaptation of cavefish to nutrient-poor conditions. A Aspiras, N Rohner, B Marineau, R Borowsky, J Tabin, Proceedings of the National Academy of Sciences. 1122015
A E Aulsebrook, T M Jones, N C Rattenborg, T C Roth, J A Lesku, Sleep Ecophysiology: Integrating Neuroscience and Ecology. 201631
Circadian rhythms in Mexican blind cavefish Astyanax mexicanus in the lab and in the field. A Beale, C Guibal, T K Tamai, L Klotz, S Cowen, Nat Commun. 427692013
A potential benefit of albinism in Astyanax cavefish: downregulation of the oca2 gene increases tyrosine and catecholamine levels as an alternative to melanin synthesis. H Bilandzija, L Ma, A Parkhurst, W Jeffery, PLoS One. 8e808232013
Breeding Astyanax mexicanus through natural spawning. R Borowsky, Cold Spring Harb Protoc. 32008a
Drosophila insulin-like peptide 2 mediates dietary regulation of sleep intensity. R Borowsky, E B Brown, K D Shah, R Faville, B Kottler, A C Keene, Cold Spring Harb Protoc. 32008b. 2020PLoS Genet
Starvation resistance is associated with developmentally specified changes in sleep, feeding and metabolic rate. E B Brown, M E Slocumb, M Szuperak, A Kerbs, A G Gibbs, Journal of Experimental Biology. 2222019
Phylogenetic analysis of the ecology and evolution of mammalian sleep. I Capellini, R A Barton, P Mcnamara, B T Preston, C L Nunn, Evolution (N Y). 622008
Genetic analysis reveals candidate genes for activity QTL in the blind Mexican tetra, Astyanax mexicanus. B M Carlson, I B Klingler, B J Meyer, J B Gross, PeerJ. 6e51892018
Regulation of zebrafish sleep and arousal states: current and prospective approaches. C N Chiu, D Prober, Front Neural Circuits. 7582013
A zebrafish genetic screen identifies neuromedin U as a regulator of sleep/wake states. C N Chiu, J Rihel, D A Lee, C Singh, E A Mosser, Neuron. 892016
Nutritional value of brine shrimp cysts as a factitious food for Orius laevigatus (Heteroptera: Anthocoridae). P De Clercq, Y Arijs, T Van Meir, G Van Stappen, P Sorgeloos, Biocontrol Sci Technol. 152005
Unraveling stress resilience: Insights from adaptations to extreme environments by Astyanax mexicanus cavefish. A E Cobham, N Rohner, J Exp Zool B Mol Dev Evol. 2024
Dependence of sleep on nutrient's availability. J Danguir, S Nicolaidis, Physiol Behav. 221979
2012 β-adrenergic signaling regulates evolutionarily derived sleep loss in the mexican cavefish. E R E R Duboué, R L R L Borowsky, A C A C Keene, Brain Behav Evol. 80
Evolutionary convergence on sleep loss in cavefish populations. E R Duboué, A C Keene, R L Borowsky, Current Biology. 212011
Astyanax transgenesis and husbandry: how cavefish enters the laboratory. Y Elipot, L Legendre, S Père, F Sohm, S Rétaux, Zebrafish. 112014
Enhanced prey capture skills in Astyanax cavefish larvae are independent from eye loss. L Espinasa, J Bibliowicz, W R Jeffery, S Rétaux, Evodevo. 52014
Contrasting feeding habits of post-larval and adult Astyanax cavefish. L Espinasa, N Bonaroti, J Wong, K Pottin, E Queinnec, Subterr Biol. 212017
Retinotectal circuitry of larval zebrafish is adapted to detection and pursuit of prey. D Förster, T O Helmbrecht, D S Mearns, L Jordan, N Mokayes, 20209
Evolutionary increases in catecholamine signaling may underlie the emergence of adaptive traits and behaviors in the blind cavefish, Astyanax mexicanus. K Gallman, D Rivera, D Soares, 10.1101/72:2019
Hypothalamic Neurons that Regulate Feeding Can Influence Sleep/Wake States Based on Homeostatic Need. N Goldstein, B J Levine, K A Loy, W L Duke, O S Meyerson, Curr Biol. 282018e3
The complex origin of Astyanax cavefish. J B Gross, 10.1186/1471-2148-12-105BMC Evol. Biol. 121052012
The role of gene flow in rapid and repeated evolution of cave-related traits in Mexican tetra. A Herman, Y Brandvain, J Weagley, W R Jeffery, A C Keene, Astyanax mexicanus. Mol Ecol. 222018
Automated Measurements of Sleep and Locomotor Activity in Mexican Cavefish. J B Jaggard, E Lloyd, A Lopatto, E R Duboue, A C Keene, J Vis Exp. 2019a
Automated Measurements of Sleep and Locomotor Activity in Mexican Cavefish. J B Jaggard, E Lloyd, A Lopatto, E R Duboue, A C Keene, J Vis Exp. 2019b
Cavefish brain atlases reveal functional and anatomical convergence across independently evolved populations. J B Jaggard, E Lloyd, A Yuiska, A Patch, Y Fily, Sci Adv. 62020. 2018Hypocretin underlies the evolution of sleep loss in the Mexican cavefish
Regressive evolution in Astyanax cavefish. W R Jeffery, Annu Rev Genet. 432009
Unraveling the Evolutionary Determinants of Sleep. W J Joiner, Current Biology. 262016
A C Keene, L Appelbaum, Sleep in Fish Models. 2019
Clock and cycle limit starvation-induced sleep loss in drosophila. A C Keene, E R Duboue ; Keene, A C A C , E R E R Duboué, D M D M Mcdonald, M Dus, G S B G S B Suh, Current Biology. 202018. 2010J Exp Biol
. A C Keene, M Yoshizawa, S E Mcgaugh, Biology and Evolution of the Mexican Cavefish. 2015
CRISPR mutagenesis confirms the role of oca2 in melanin pigmentation in Astyanax mexicanus. H Klaassen, Y Wang, K Adamski, N Rohner, J E Kowalko, Dev Biol. 4412018
Convergence in feeding posture occurs through different genetic loci in independently evolved cave populations of Astyanax mexicanus. J E Kowalko, N Rohner, T A Linden, S B Rompani, W C Warren, Proceedings of the National Academy of Sciences. 1102013
A simple and effective F0 knockout method for rapid screening of behaviour and other complex phenotypes. F Kroll, G T Powell, M Ghosh, G Gestri, P Antinucci, Am J Respir Crit Care Med. 102021. 2010A Candidate Gene Study of Obstructive Sleep Apnea in European Americans and African Americans
A phylogenetic analysis of sleep architecture in mammals: the integration of anatomy, physiology, and ecology. J A Lesku, T C Roth, C J Amlaner, S L Lima, Am Nat. 1682006
Neural signatures of sleep in zebrafish. L C Leung, G X Wang, R Madelaine, G Skariah, K Kawakami, Nature. 5712019
Modeling sleep and neuropsychiatric disorders in zebrafish. T Levitas-Djerbi, L Appelbaum, Curr Opin Neurobiol. 442017
Evolutionary shift towards lateral line dependent prey capture behavior in the blind Mexican cavefish. E Lloyd, C Olive, B A Stahl, J B Jaggard, P , Dev Biol. 2018
Starvation and human slow-wave sleep. U Macfadyen, I Oswald, S Lewis, J Appl Physiol. 351973
Repeated evolution of circadian clock dysregulation in cavefish populations. K L Mack, J B Jaggard, J L Persons, E Y Roback, C N Passow, PLoS Genet. 172021
Regulation of Satiety Quiescence by Neuropeptide Signaling in Caenorhabditis elegans. M Makino, E Ulzii, R Shirasaki, J Kim, Y.-J You, Front Neurosci. 156785902021
Dark world rises: The emergence of cavefish as a model for the study of evolution, development, behavior, and disease. S E Mcgaugh, J E Kowalko, E Duboué, P Lewis, T A Franz-Odendaal, J Exp Zool B Mol Dev Evol. 3342020
Evolution of sleep: phylogenetic and functional perspectives. P Mcnamara, R Barton, C Nunn, 2009
The metabolome of Mexican cavefish shows a convergent signature highlighting sugar, antioxidant, and Ageing-Related metabolites. J K Medley, J Persons, T Biswas, L Olsen, R Peuß, 202211
Selection-driven trait loss in independently evolved cavefish populations. R Moran, E Richards, C Ornelas-Garcia, J Gross, A Gross, BioRxiv. 5181852022
Eyeless Mexican Cavefish Save Energy by Eliminating the Circadian Rhythm in Metabolism. D Moran, R Softley, E J Warrant, PLoS One. 9e1078772014
. K R K R Murphy, S A S A Deshpande, M E M E Yurgel, J P J P Quinn, J L J L Weissbach, Postprandial sleep mechanics in Drosophila. Elife. 52016
Pleiotropic function of the oca2 gene underlies the evolution of sleep loss and albinism in cavefish. M O'gorman, S Thakur, G Imrie, R L Moran, S Choy, Curr Biol. 312021e4
Peripheral injections of cholecystokinin, apelin, ghrelin and orexin in cavefish (Astyanax fasciatus mexicanus): effects on feeding and on the brain expression levels of tyrosine hydroxylase, mechanistic target of rapamycin and appetiterelated hormones. C Penney, H Volkoff, Gen Comp Endocrinol. 1962014
Severe obstructive sleep apnea in a child with melanocortin-4 receptor deficiency. S Pillai, K Nandalike, Y Kogelman, R Muzumdar, S J Balk, J Clin Sleep Med. 102014
Starvationresistant cavefish reveal conserved mechanisms of starvation-induced hepatic lipotoxicity. M Pozo-Morales, A E Cobham, C Centola, M C Mckinney, P Liu, Life Sci Alliance. 72024
Increased food intake after starvation enhances sleep in Drosophila melanogaster. J M Regalado, M B Cortez, J Grubbs, J A Link, A Van Der Linden, J Genet Genomics. 442017
Genetic mapping of metabolic traits in the blind Mexican cavefish reveals sex-dependent quantitative trait loci associated with cave adaptation. M R Riddle, A Aspiras, F Damen, S Mcgaugh, J A Tabin, BMC Ecol Evol. 21942021
Zebrafish behavioral profiling links drugs to biological targets and rest/wake regulation. J Rihel, D A Prober, A Arvanites, K Lam, S Zimmerman, Science. 3272010
Cave colonization without fasting capacities: An example with the fish Astyanax fasciatus mexicanus. K Salin, Y Voituron, J Mourin, F Hervant, Comp Biochem Physiol A Mol Integr Physiol. 1562010
Fiji: an open-source platform for biological-image analysis. J Schindelin, I Arganda-Carreras, E Frise, V Kaynig, M Longair, Nat Methods. 92012
The evolution of metabolic regulation in animals. F Seebacher, Comp Biochem Physiol B Biochem Mol Biol. 2242018
A dedicated visual pathway for prey detection in larval zebrafish. J L Semmelhack, J C Donovan, T R Thiele, E Kuehn, E Laurell, 20143
Norepinephrine is required to promote wakefulness and for hypocretin-induced arousal in zebrafish. C Singh, G Oikonomou, D A Prober, 20154e070000
. C Singh, J Rihel, D A Prober, 2017
Y Neuropeptide, Regulates, Sleep by Modulating Noradrenergic Signaling. 27e5
Enhanced Sleep Is an Evolutionarily Adaptive Response to Starvation Stress in Drosophila. M E Slocumb, J M Regalado, M Yoshizawa, G G Neely, P Masek, PLoS One. 10e01312752015
Postprandial sleepiness: objective documentation via polysomnography. M L Stahl, W C Orr, C Bollinger, Sleep. 61983
Sleep-Dependent Modulation of Metabolic Rate in Drosophila. B A Stahl, M E Slocumb, H Chaitin, J R Diangelo, A C Keene, Sleep. 402017
Feeding Behavior, Starvation Response, and Endocrine Regulation of Feeding in Mexican Blind Cavefish (Astyanax fasciatus mexicanus). H Volkoff, Biology and Evolution of the Mexican Cavefish. 2016Elsevier
| [
-0.05423352122306824,
0.04220890626311302,
0.01692763902246952,
0.1682567596435547,
0.009839389473199844,
0.07509879767894745,
-0.09512299299240112,
-0.08853840827941895,
0.03883941471576691,
-0.0060506961308419704,
-0.0625753402709961,
-0.2787973880767822,
0.016181746497750282,
0.01775687... |
THE LOWER BOUND OF THE PCM QUANTIZATION ERROR IN HIGH DIMENSION
18 Mar 2014
Heng Zhou
Zhiqiang Xu
THE LOWER BOUND OF THE PCM QUANTIZATION ERROR IN HIGH DIMENSION
18 Mar 2014D1E03A7F3DAAD18AC06BB2BDE1C7ADF3arXiv:1403.4311v1[math.NA]AMS Subject Classification 2000 42C1533C1042A05
In this note, we investigate the performance of the PCM scheme with linear quantization rule for quantizing unit-norm tight frame expansions for R d without the White Noise Hypothesis.In [4], Wang and Xu showed that for asymptotically equidistributed unit-norm tight frame the PCM quantization error has an upper bound O(δ (d+1)/2 ) and they conjecture the upper bound is sharp.In this note, we confirm the conjecture with employing the asymptotic estimate of the Bessel functions.
Introduction
In signal processing, one of the primary goals is to find a digital representation for a given signal that is suitable for storage, transmission, and recovery.We assume that the signal x is an element of a finite-dimensional Hilbert space H = R d .One often begins to expand x over a dictionary F = {e j } N j=1 , i.e.,
x = N j=1 c j e j ,
where c j are real numbers.We say F is a tight frame of
R d if x = d N N j=1
x, e j e j holds for all x ∈ R d .The tight frame is called unit-norm if e j 2 = 1 holds for all 1 ≤ j ≤ N .
In the digital domain the coefficients x j = x, e j must be mapped to a discrete set of values A which is called the quantization alphabet.The simplest way for such a mapping is the Pulse Code Modulation (PCM) quantization scheme, which has A = δZ with δ > 0 and the mapping is done by the function
Q δ (t) := argmin r∈A |t − r| = δ t δ + 1 2 .
Z. Xu is supported by the National Natural Science Foundation of China (11171336 and 11331012) and by the Funds for Creative Research Groups of China (Grant No. 11021101).
Thus in practical applications we in fact have only a quantized representation q j := Q δ ( x, e j ), j = 1, . . ., N
for each x ∈ R d .The linear reconstruction is
xF = d N N j=1
q j e j .
Naturally we are interested in the error for this reconstruction, i.e.
E δ (x, F ) := x − xF ,
where • is ℓ 2 norm.To simplify the investigation of E δ (x, F ), one employs the White Noise Hypothesis (WNH) in this area (see [6,8,9,10,11,5]), which asserts that the quantization error sequence {x j − q j } N j=1 can be modeled as an independent sequence of i.i.d.random variables that are uniformly distributed on the interval (−δ/2, δ/2).Under the WNH, one can obtain the mean square error
M SE = E( x − xF 2 ) = d 2 δ 2 12N .
The result implies that the MES of E δ (x, F ) tends to 0 with N tending to infinity.However, as pointed out in [11,5], the WNH only asymptotically holds for fine quantization (i.e. as δ tends to 0) under rather general conditions.So, for a fixed x, one is interested in whether E δ (x, F ) really tending to 0 without WNH.The result in [4] gives a solution for the case where d = 2 which shows that for some x ∈ R 2 the quantization error E δ (x, F ) does not diminish to 0 with N tending to infinity.Naturally, one would like to know whether it is possible to extend the result to higher dimension.In [4], Wang and Xu investigate the case where F is the asymptotically equidistributed unit-norm tight frame in R d .A sequence of finite sets A m ⊂ S d−1 with cardinality N m = #A m is said to be asymptotically equidistributed on S d−1 if for any piecewise continuous function f on S d−1 we have
lim m→∞ 1 N m v∈Am f (v) = z∈S d−1 f (z)dν,
where f are piecewise continuous functions on S d−1 and dν denotes the normalized Lebesgue measure on S d−1 .Then the following theorem presents an upper bound for lim m→∞ E δ (x, F m ).
Theorem 1.1.[4] Assume that F m are asymptotically equidistributed unit-norm tight frames in R d .Then for any x ∈ R d we have
lim m→∞ E δ (x, F m ) ≤ C d δ (d+1)/2 r (d−1)/2 ,
where r = x and C d is a constant depending on d.
A main tool for obtaining Theorem 1.1 is Euler-Maclaurin formula.However, it seems that it is difficult to extend the method to obtain the lower bound.In [4], Wang and Xu conjecture the bound O δ (d+1)/2 r (d−1)/2 is sharp.In this note, we employ the tools of Bessel function and hence confirm the conjecture.In particular, we have: Theorem 1.2.Suppose that d > 2 is an integer.Assume that x ∈ R d and that F m are asymptotically equidistributed unit-norm tight frames in R d .Set r := x , R := r/δ, ǫ := R − ⌊R⌋, and
I := d 2π 0 |(sin(θ 2 )) d−3 • • • sin θ d−2 |dθ 2 • • • dθ d−2 > 0. (i) If d = 2n and 1/4 ≤ ǫ ≤ 1/2, then lim m→∞ E δ (x, F m ) ≥ C 1,d δ d+1 2 r d−1 2
, provided that R = x /δ is big enough, where
C 1,d = (n − 1)! • 2n−2 n−1 • M 1 2 2n−2 π n • I, M 1 = 4 5 | cos(2πǫ − 3 4 π)| − 5 4 +∞ k=2 1 k 2n+1 2 > 0. (ii) If d = 2n + 1 and 1/6 ≤ ǫ ≤ 1/3, then lim m→∞ E δ (x, F m ) ≥ C 2,d δ d+1 2 r d−1 2
, provided that R = x /δ is big enough, where
C 2,d = (n − 1)! • M 2 π n+1 • I, M 2 = 7 8 | cos(2πǫ − 1 2 π)| − 8 7 +∞ k=2 1 k n+1 > 0.
After introducing some necessary concepts and results to be used in our investigation in Section 2, we present the proof of Theorem 1.2 in Section 3.
Preliminaries
Bessel function.(see [12]) For α > 0, the Bessel function J α is defined by the series representation (1)
J α (x) = +∞ k=0 (−1) k k! • Γ(k + α + 1) x 2 2k+α .
Particularly, when α ∈ N, we have
J α (x) = 1 π π 0 cos(ατ − x sin(τ ))dτ.
We also need an asymptotic estimate for the Bessel function J α which is presented in [2].
Theorem 2.1.( [2]) For the Bessel function J α , we have
J α (x) = 2 πx cos(x − ω α ) + θcµx − 3 2 ,
where
ω α = πα 2 + 1 4 π, µ = |α 2 − 1 4 |, |θ| ≤ 1, and c = (2/π) 3/2 , x ≥ 0, |α| ≤ 1 2 √ 2/2, x ≥ √ µ, α > 1 2 5/4, 0 < x < √ µ, α > 1 2 .
Combinatorics identity.(see (7.7) of Table 4 in [1])
(2)
h m=0 (−1) m n + h h − m n + h h + m = 1 2 n + h h + 1 2 n + h h 2 3. Proof of Theorem 1.2
To this end, we first introduce several lemmas:
Lemma 3.1. For all n ∈ N + and h ∈ N we have h m=0 (−1) m (2m + 1) n + h h − m n + h h + m + 1 = n n + h n ,(3)and h m=l (−1) m (2m + 1) 2h + 1 h − m m + l 2l = 0, l = 0, 1, . . . , h − 1. (4)
Proof.We prove (3) by induction.To state conveniently, set
A h n := h m=0 (−1) m (2m + 1) n + h h − m n + h h + m + 1 .
A simple observation is that (3) holds when n ∈ N + , h = 0 and when n = 0, h ∈ N + .Assume that n 0 , h 0 ∈ N + .For the induction step, we assume that ( 3) is true both for n ≤ n 0 ∈ N + , h ∈ N + and for n = n 0 + 1, h ≤ h 0 − 1 ∈ N + .To this end, we just need prove that the result holds for n = n 0 + 1, h = h 0 .We have
A h 0 n 0 +1 = h 0 m=0 (−1) m (2m + 1) n0 + h0 + 1 h0 − m n0 + h0 + 1 h0 + m + 1 = h 0 m=0 (−1) m (2m + 1) n0 + h0 h0 − m + n0 + h0 h0 − m − 1 n0 + h0 h0 + m + 1 + n0 + h0 h0 + m = A h 0 n 0 + A h 0 −1 n 0 +1 + h 0 m=0 (−1) m (2m + 1) n0 + h0 h0 − m n0 + h0 h0 + m + n0 + h0 h0 − m − 1 n0 + h0 h0 + m + 1 = A h 0 n 0 + A h 0 −1 n 0 +1 + 2 h 0 m=0 (−1) m n0 + h0 h0 − m n0 + h0 h0 + m − n0 + h0 h0 2 = A h 0 n 0 + A h 0 −1 n 0 +1 + n0 + h0 n0 = (n0 + 1) n0 + h0 + 1 n0 + 1 ,
where the last equality uses the identity (2) and the induction assumption.We now turn to (4).Set
(5)
g m := (−1) m+1 (h + m + 1)(m − l) 2h+1 h−m m+l 2l h − l .
A simple calculation shows that (6)
g m+1 − g m =(−1) m 2h+1 h−m m+l 2l h − l ((h − m)(l + m + 1) + (h + m + 1)(m − l)) =(−1) m (2m + 1) 2h + 1 h − m m + l 2l . Then h m=l (−1) m (2m + 1) 2h + 1 h − m m + l 2l = m≥l (−1) m (2m + 1) 2h + 1 h − m m + l 2l = m≥l g m+1 − g m = g l = 0.
Here, the first equality holds since n k = 0 provided k < 0.
Remark 1.A key step to prove ( 4) is to construct the sequence g m which satisfies (6).In the proof of Lemma 3.1, we obtain g m using Gosper algorithm [7].However, it is also simple to verify (6) by hand.
We introduce the following results for Bessel functions
Lemma 3.2. Set L m := π −π cos(2m + 1)θ cos θ(sin θ) 2n−2 dθ D m := π 0 cos(2m + 1)θ cos θ(sin θ) 2n−1 dθ.
Then we have
n−1 m=0 (−1) m L m J 2m+1 (x) = L 0 2 n−1 n! 1 x n−1 J n (x), (7) +∞ m=0 (−1) m D m J 2m+1 (x) = √ π2 n− 3 2 (n − 1)! 1 x n− 1 2 J n+ 1 2 (x).(8)
Proof.To this end, we first calculate the value of L m .Using the expansion
sin 2n−2 θ = 1 2 2n−2 2n − 2 n − 1 + 2 2 2n−2 n−2 k=0 (−1) n−1−k 2n − 2 k cos((2n − 2 − 2k)θ),
we can obtain that (9)
L m = (−1) m π 2 2n−2 2n − 2 n + m − 1 2m + 1 n + m .
Recall that the series representation of the Bessel function J α (10)
J α (x) = +∞ k=0 (−1) k k!Γ(k + α + 1) x 2 2k+α .
Substituting (10) into (7) we obtain that (11
) +∞ k=0 (−1) k k! n−1 m=0 (−1) m L m 1 Γ(2m + k + 2) x 2 2k+2m+1 = L 0 •n!• +∞ k=0 (−1) k k! • Γ(k + n + 1) x 2 2k+1 .
To this end, we just need prove (11).Comparing the coefficients of the powers of x on the both sides of (11), we only need prove
h m=0 L m 1 (h − m)! • Γ(h + m + 2) = L 0 • n! • 1 h! • Γ(h + n + 1) ,(12)
which is equivalent to
(13) h m=0 (−1) m (2m + 1) n + h h − m n + h h + m + 1 = n n + h n .
Here, we use (9).According to Lemma 3.1, (13) holds which in turn implies (7).
We next turn to (8).Substitute ( 10) into ( 8) and compare the coefficients of the powers of x on the two sides of this equation, we only need to prove
h m=0 D m (h − m)! • (h + m + 1)! = (n − 1)! 4 • 2 2h+2n+3 • (h + n + 1)! h! • (2h + 2n + 2)! , h = 0, 1, . . . . (14) Using cos nx = n 2 ⌊ n 2 ⌋ k=0 (−1) k n − k k (2 cos x) n−2k n − k ,
and
π 2 0 (sin t) x (cos t) y dt = π 2 x+y+1 x! • y! ( x 2 )! • ( y 2 )! • ( x+y 2 )!
, where x! = Γ(x + 1) for x > 0, we have
(15) D m = (2m + 1) m k=0 (−1) k 2m + 1 − k k √ π(n − 1)! 4(2m + 1 − k) (2m + 2 − 2k)! (m + 1 − k)! • ( 2m+2n−2k+1 2 )! .
Substituting (15) into (14), we can rewrite (14) as ( 16)
h m=0 2m + 1 (h − m)! • (h + m + 1)! m k=0 (−1) k 2m + 1 − k k 1 2m + 1 − k (2m + 2 − 2k)! (m + 1 − k)! • ( 2m+2n−2k+1 2 )! = 1 √ π 2 2h+2n+3 (h + n + 1)! h! • (2h + 2n + 2)! .
On the other hand, we can rewrite the left side of ( 16) as (17)
h m=0 2m + 1 (h − m)! • (h + m + 1)! m k=0 (−1) k 2m + 1 − k k 1 2m + 1 − k (2m + 2 − 2k)! (m + 1 − k)! • ( 2m+2n−2k+1 2 )! = h m=0 2m + 1 (h − m)! • (h + m + 1)! m l=0 (−1) m−l m + l + 1 m − l 1 m + l + 1 (2l + 2)! (l + 1)! • ( 2l+2n+1 2 )! = h l=0 1 ( 2l+2n+1 2 )! h m=l 2m + 1 (h − m)! • (h + m + 1)! (−1) m−l m + l + 1 m − l 1 m + l + 1 (2l + 2)! (l + 1)! .
Here, in the first equality, we set a new variable l := m − k.To this end, we consider the second term on the right side of the last equality in (17).Note that, for l = 0, . . ., h − 1,
h m=l 2m + 1 (h − m)! • (h + m + 1)! (−1) m−l m + l + 1 m − l 1 m + l + 1 (2l + 2)! (l + 1)! = (−1) l (2l + 2)! (2l + 1)(2h + 1)! • (l + 1)! h m=l (2m + 1) 2h + 1 h − m (−1) m m + l 2l = 0.
Here, the last equality follows from (4) in Lemma 3.1.Hence the last summation in (17
) is reduced to 1 ( 2h+2n+1 2 )! 2h + 1 (h + h + 1)! (−1) h−h h + h + 1 h − h 1 h + h + 1 (2h + 2)! (h + 1)! = 1 ( 2h+2n+1 2 )! 2 h! = 1 √ π 2 2h+2n+3 (h + n + 1)! h! • (2h + 2n + 2)! .
Here, the last equality uses
2h + 2n + 1 2 ! = Γ h + n + 1 + 1 2 = (2h + 2n + 2)! 2 2h+2n+2 (h + n + 1)! √ π.
We arrive at the conclusion.
Now we can give an estimation for the integrals
(n − 1)! • 2n−2 n−1 M 1 2 2n−2 • π n δ 2n+1 2 r 2n−1 2 ≤ π 0 ∆ δ (r cos θ) cos θ(sin θ) 2n−2 dθ ≤ 5 4 (n − 1)! • 2n−2 n−1 +∞ k=1 1 k 2n+1 2 2 2n−2 • π n δ 2n+1 2 r 2n−1 2 , provided that R = r δ is big enough, where M 1 = 4 5 | cos(2πǫ − 3 4 π)| − 5 4 +∞ k=2 1 k 2n+1 2 > 0 and n ≥ 2. When 1/6 ≤ ǫ ≤ 1/3, we have (19) M 2 (n − 1)! π n+1 δ n+1 r n ≤ π 0 ∆ δ (r cos θ) cos θ(sin θ) 2n−1 dθ ≤ 8 7 (n − 1)! +∞ k=1 1 k n+1 π n+1 δ n+1 r n , provided that R = r δ is big enough, where M 2 = 7 8 | cos(2πǫ − 1 2 π)| − 8 7 +∞ k=21k n+1 > 0 and n ≥ 1.
Proof.Firstly we consider π 0 ∆ δ (r cos θ) cos θ(sin θ) 2n−2 dθ.Using the Fourier expansion for ⌊x⌋ with x ∈ R \ Z,
⌊x⌋ = x − 1 2 + 1 π +∞ k=1 sin(2kπx) k ,
we have (20
) π 0 ∆ δ (r cos θ) cos θ(sin θ) 2n−2 dθ = 1 2 π −π ∆ δ (r cos θ) cos θ(sin θ) 2n−2 dθ = − δ 2π π −π +∞ k=1 sin(2kπ r cos θ δ + kπ) k cos θ(sin θ) 2n−2 dθ = − δ 2π +∞ k=1 (−1) k k π −π sin(2kπ r δ cos θ) cos θ(sin θ) 2n−2 dθ = − δ π +∞ k=1 (−1) k k n−1 m=0 (−1) m L m J 2m+1 (2kπ r δ ) = − δ π • L 0 • 2 n−1 n! +∞ k=1 (−1) k k 1 (2kπ r δ ) n−1 • J n (2kπ r δ ) = − 1 π n • δ n r n−1 • L 0 • n! • ∞ k=1 (−1) k k n J n (2kπ r δ ) = − 1 π n • δ n r n−1 • π 2 2n−2 • 2n − 2 n − 1 • (n − 1)! • ∞ k=1 (−1) k k n J n (2kπ r δ ).
In the fourth equality, we use the formula
sin(x cos θ) = 2 +∞ m=0 (−1) m cos((2m + 1)θ)J 2m+1 (x)
and the orthogonality of the systems {cos kx} +∞ k=0 on the interval [−π, π].We use (7) in the fifth equality.To this end, according to (20), we only need to estimate
+∞ k=1 (−1) k k n J n (2kπ r δ ) .
In fact, note that
(21) |J n (2π r δ )| − +∞ k=2 1 k n |J n (2kπ r δ )| ≤ +∞ k=1 (−1) k k n J n (2kπ r δ ) ≤ +∞ k=1 1 k n |J n (2kπ r δ )|. We first consider |J n (2π r δ )| − +∞ k=21k n |J n (2kπ r δ )|.
Using the asymptotic estimate for J n (x) in Theorem 2.1, we have
(22) J n (2π r δ ) = 1 π δ r cos(2π r δ − ω n ) + θcµ(2π r δ ) −3/2 = 1 π δ r cos(2πǫ − (2n + 1)π 4 ) + θcµ( 1 2π δ r ) 3/2
which implies that
J n (2π r δ ) ≥ 4 5 1 π δ r cos(2πǫ −3π 4 )
provided that R = r δ is big enough.On the other hand,
+∞ k=2 1 k n |J n (2kπ r δ )| = +∞ k=2 1 k n 1 π δ kr cos(2πk r δ − ω n ) + θcµ(2πk r δ ) −3/2 = +∞ k=2 1 k n 1 π δ kr cos(2πkǫ − (2n + 1)π 4 ) + θcµ(2πk r δ ) −3/2 .(23)
Therefore, according to (22),
+∞ k=2 1 k n |J n (2kπ r δ )| ≤ 5 4π δ r +∞ k=2 1 k 2n+1 2
provided that R = r δ is big enough.Combining above results, we obtain that
(24) |J n (2π r δ )| − +∞ k=2 1 k n |J n (2kπ r δ )| ≥ 1 π δ r 4 5 cos(2πǫ − 3π 4 ) − 5 4 +∞ k=2 1 k 2n+1 2
, provided that R = r δ is big enough.When 1/4 ≤ ǫ ≤ 1/2 and n ≥ 2,
M 1 := 4 5 cos(2πǫ − 3π 4 ) − 5 4 +∞ k=2 1 k 2n+1 2 ≥ 4 5 • √ 2 2 − 5 4 +∞ k=2 1 k 5 2 ≈ 0.138 > 0.
Combining (20), ( 21) and ( 24), we obtain the left side of (18).Similarly, based on (23), we have
+∞ k=1 (−1) k k n J n (2kπ r δ ) ≤ +∞ k=1 1 k n J n (2kπ r δ ) ≤ 5 4 1 π δ r +∞ k=1 1 k 2n+1 2
provided that R = r δ is big enough, which implies the right side of (18).Now let us turn to
= − δ π +∞ k=1 (−1) k k π 0 sin(2kπ r δ cos θ) cos θ(sin θ) 2n−1 dθ = − 2δ π +∞ k=1 (−1) k k +∞ m=0 (−1) m D m J 2m+1 (2kπ r δ ) = − 2δ π √ π2 n− 3 2 (n − 1)! +∞ k=1 (−1) k k 1 (2kπ r δ ) n− 1 2 J n+ 1 2 (2kπ r δ ) = − (n − 1)! π n δ n+ 1 2 r n− 1 2 +∞ k=1 (−1) k k n+ 1 2 J n+ 1 2 (2kπ r δ ),
where we use (8) in Lemma 3.2 for the fourth equality.Using the asymptotic estimate for J n+ 1 2 (x) in Theorem 2.1, similarly with the above, we can show that (26) 1 π δ r
7 8 | cos(2πǫ − 1 2 π)| − 8 7 +∞ k=2 1 k n+1 ≤ | +∞ k=1 (−1) k k n+ 1 2 J n+ 1 2 (2kπ r δ )| ≤ 8 7 1 π δ r +∞ k=1 1 k n+1 provided that R = r δ is big enough. When 1/6 ≤ ǫ ≤ 1/3 and n ≥ 1, M 2 := 7 8 | cos(2πǫ − 1 2 π)| − 8 7 +∞ k=2 1 k n+1 ≥ 7 8 • √ 3 2 − 8 7 +∞ k=2 1 k 2 ≈ 0.02 > 0.
Combing (25) and (26), we arrive at (19).
We now can state the proof of the main theorem.
Proof of Theorem 1.2.The idea to prove Theorem 1.2 is similar to one of proving Theorem 1.1 in [4] with using Lemma 3.3 to estimate lim m→∞ E δ (x, F m ).We state the proof of (i) for the completeness.In fact, (ii) can be proved using a similar method.
We denote the number of the non-zero entries in x by x 0 , i.e.,
x 0 := #{j : x j = 0}.
The proof is by induction on x 0 .Note that
lim m→∞ E δ (x, F m ) = lim m→∞ d N m Nm j=1 ∆ δ (x • e j )e j = d z∈S d ∆ δ (x • z)zdω .
We begin with x 0 = 1.Without loss of generality, we suppose x = [x 1 , 0, . . ., 0] T ∈ R d and consider lim m→∞ E δ (x, F m ).By the sphere coordinate system, each z = [z 1 , . . ., z d ] ∈ S d−1 can be written in the form of
[cos θ 1 , sin θ 1 cos θ 2 , sin θ 1 sin θ 2 cos θ 3 , . . . , sin θ 1 • • • sin θ d−1 ] ⊤ ,
where θ 1 ∈ [0, π) and θ j ∈ [−π, π), 2 ≤ j ≤ d − 1.To state conveniently, we set where the last inequality follows from Lemma 3.3.
Θ := [0, π) × [−π, π) × • • • × [−π, π) d−2 , S t(
For the induction step, we suppose that the conclusion holds for the case where x 0 ≤ k.We now consider x 0 ≤ k + 1.Without loss of generality, we suppose x is in the form of [0, . . ., 0, x d−k , . . ., x d ] ∈ R d .We can write [x d−1 , x d ] in the form of (r 0 cos ϕ 0 , r 0 sin ϕ 0 ), where r 0 ∈ R + and ϕ 0 ∈ [0, 2π).Then where the last inequality follows from the fact x 0 ≤ k provided ϕ 0 = 0.
π 0 ∆
0
δ (r cos θ) cos θ(sin θ) 2n−2 dθ and π 0 ∆ δ (r cos θ) cos θ(sin θ) 2n−1 dθ.Lemma 3.3.Set R := r δ and ǫ := R − ⌊R⌋.Then when 1/4 ≤ ǫ ≤ 1/2 (18)
π 0 ∆
0
δ (r cos θ) cos θ(sin θ) 2n−1 dθ.Similar with the above,we have (25) π 0 ∆ δ (r cos θ) cos θ(sin θ) 2n−1 dθ sin θ) 2n−1 dθ
− 1 ∆− 1 ∆ δ (x • z)zdω = d z∈S d− 1 ∆ 1 ≥
1111
θ) := t j=1 sin θ j and J d (θ) := (sin θ 1 ) d−2 (sin θ 2 ) d−3 • • • (sin θ d−2 ) .Noting that dω = J d (θ)dθ 1 • • • dθ d−1 and z∈S dδ (x 1 z 1 )z j dω = 0, 2 ≤ j ≤ d − 1, we have lim m→∞ E δ (x, F m ) = d z∈S dδ (x 1 z 1 )z 1 dω = d θ∈Θ ∆ δ (x 1 cos θ 1 ) cos θ 1 (sin θ 1 ) d−2 |(sin θ 2 ) d−3 • • • (sin θ d−2 )|dθ 1 • • • dθ d−C 1,d • δ (d+1)/2 /|x 1 | (d−1)/2
2 .
2
x j S j (θ) cos θ j + r 0 sin θ1 • • • sin θ d−2 cos(θ d−1 − ϕ 0 ) =: T (ϕ 0 ).A simple observation is θ∈Θ ∆ δ (T (ϕ 0 ))S d−2 (θ)J d (θ) cos θ d−1 dθ 2 + θ∈Θ ∆ δ (T (ϕ 0 ))S d−2 (θ)J d (θ) sin θ d−1 dθ 2 = θ∈Θ ∆ δ (T (0))S d−2 (θ)J d (θ) cos θ d−1 dθ 2 + θ∈Θ ∆ δ (T (0))S d−2 (θ)J d (θ) sin θ d−1 dθ Then we have lim m→∞ E δ (x, F m ) = d z∈S d−1 ∆ δ (x • z)zdω
(
θ∈Θ ∆ δ (T (ϕ 0 ))S t−1 (θ)J d (θ) cos θ t dθ) 2 + ( θ∈Θ ∆ δ (T (ϕ 0 ))S d−1 (θ)J d (θ)dθ)
( 2 1/ 2 ≥
22
θ∈Θ ∆ δ (T (0))S t−1 (θ)J d (θ) cos θ t dθ) 2 + ( θ∈Θ ∆ δ (T (0))S d−1 (θ)J d (θ)dθ) C 1,d • δ (d+1)/2 /r (d−1)/2
Combinatorial Identities -eight tables based on seven unpublished manuscript notebooks. H W Gould, Prof.Jocelyn Quaintance1945-1990. May 2010
Ilia Krasikov, arXiv:1107.2007arxiv.orgSome asymptotics for the Bessel functions with an explicit error term. 2011arXiv preprint
Optimal frames for erasures. R Holmes, V Paulsen, Linear Algebra Appl. 3772004
The performance of PCM quantization under tight frames representations. Yang Wang, Zhiqiang Xu, SIAM J. MATH. ANAL. 442012
White noise hypothesis for uniform quantization errors. D Jimenez, L Wang, Y Wang, SIAM J. Math. Anal. 382007
Quantized overcomplete expansions in R n : Analysis, synthesis, and algorithms. V Goyal, M Vetterli, N Thao, IEEE Trans. Inform. Theory. 441998
Decision Procedure for Indefinite Hypergeometric Summation. Rw Gosper, Proc. Natl. Acad. Sci. USA. Natl. Acad. Sci. USAJanuary 197875
W Bennett, Spectra of quantized signals. 194827
Sigma-delta quantization and finite frames. J Benedetto, A M Powell, Ö Yılmaz, IEEE Trans. Inform. Theory. 522006
Second order sigmal-delta quantization of finite frame expansions. J Benedetto, A M Powell, Ö Yılmaz, Appl. Comput. Harmon. Anal. 202006
On the distribution of uniform quantization errors. S Borodachov, Y Wang, Appl. Comput. Harmon. Anal. 272009
NIST Handbook of Mathematical Functions. F W J Olver, D W Lozier, R F Boisvert, C W Clark, Cambridge University Press2010
Email: zhouheng7598@sina.com.cn LSEC, Institute of Computational Mathematics. Beijing; China100190Chinese Academy of Sciences
| [
-0.15586209297180176,
-0.0398174487054348,
-0.06914587318897247,
-0.1299680769443512,
0.07226184010505676,
0.012988732196390629,
0.097924143075943,
-0.033566199243068695,
-0.05029866844415665,
-0.0017861300148069859,
0.016327500343322754,
0.026287894695997238,
0.08089819550514221,
-0.06985... |
Coronaviruses: Innate Immunity, Inflammasome Activation, Inflammatory Cell Death, and Cytokines
Sangjoon Lee
Rudragouda Channappanavar
Department of Microbiology, Immunology, and Biochemistry
University of Tennessee Health Sciences Center
38163MemphisTNUSA
Department of Acute and Tertiary Care
University of Tennessee Health Sciences Center
38163MemphisTNUSA
Thirumala-Devi Kanneganti
Coronaviruses: Innate Immunity, Inflammasome Activation, Inflammatory Cell Death, and Cytokines
10.1016/j.it.2020.10.005Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. Review
Innate Immunity and Coronaviruses
Innate Immunity and Inflammasomes The innate immune system functions as the first line of host defense against microbial infections. During viral infections, the innate immune system is crucial for identifying and removing infected cells while also coordinating an adaptive immune response. To detect and defend rapidly against various microbes, mammalian hosts have evolved multiple pattern-recognition receptors (PRRs; see Glossary) including Toll-like receptors (TLRs), retinoic acid-inducible gene I (RIG-I)like receptors (RLRs), the nucleotide-binding oligomerization domain (NOD)-like receptor family proteins (NLRs), and absent in melanoma 2 (AIM2). In response to specific pathogenassociated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), some PRRs, particularly members of the NLR family and AIM2, have the ability to assemble a large multiprotein complex called the inflammasome [1]. Upon assembly, the inflammasome induces membrane pore formation and proinflammatory cytokine processing, leading to a form of inflammatory cell death known as pyroptosis [1][2][3].
Innate immune signaling and inflammasome activation are well-established key barriers during viral infection. However, activation of the innate immune system must be tightly regulated, because excessive activation can lead to systemic inflammation and tissue damage, which are detrimental to the host. Systemic hyperinflammation is common in a wide range of infectious diseases [4]. Therefore, the balance between the host innate immune response and viral intracellular replication has been considered for potential therapeutic approaches in viral infections; this balance must be finely controlled to reduce excessive inflammation while retaining antiviral functions.
Coronaviruses
Coronaviruses (CoVs) are positive-sense single-stranded (ss)RNA viruses and have an extensive range of natural hosts [5]. There are seven human-infecting CoVs identified to date: human Toll-like receptor (TLR)-and retinoic acid-inducible gene I-like receptor (RLR)-mediated type I interferon (IFN) production is essential for providing protection against coronavirus (CoV) infection; the timing of the IFN response relative to CoV replication determines infection outcomes.
Optimal NLR family pyrin domaincontaining 3 (NLRP3) inflammasome activation is beneficial for the host but aberrant activation may lead to detrimental CoV infection outcomes.
Specific CoV infections can activate inflammatory cell death (PANoptosis), thereby inducing cytokine release.
CoV disease tolerance occurs in age-, species-, and sex-dependent manners.
More studies are needed to define the innate immune response, specifically during severe acute respiratory syndrome (SARS)-CoV-2 (SARS-CoV-2) infection, and to inform the development of candidate therapeutics. coronavirus 229E (HCoV-229E), HCoV-OC43, severe acute respiratory syndrome (SARS)-CoV, HCoV-NL63, HCoV-HKU1, Middle East respiratory syndrome CoV (MERS)-CoV, and SARS-CoV-2 [6,7]. The endemic HCoV-229E and HCoV-OC43 were isolated >50 years ago and are responsible for about one-third of the common cold cases each year. SARS-CoV was isolated in 2003 in China [8], while HCoV-NL63 and HCoV-HKU1 were identified shortly following the SARS-CoV outbreak. Ten years after SARS-CoV, MERS-CoV emerged in Middle Eastern countries [9]. The most recently identified human-infecting CoV is SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) [10,11], a respiratory illness in humans (Table 1). In addition to the human-infecting CoVs, there are also several other CoV strains that infect various animals. Among these, the most studied is murine hepatitis virus (MHV), which mimics many of the key aspects of human CoV biology [6]. Due to receptor specificity of human CoVs, MHV has been an ideal model for examining the pathogenesis and immune response to CoVs as well as for studying the basics of viral replication [6].
SARS-CoV, MERS-CoV, SARS-CoV-2, and MHV belong to the Betacoronavirus genus in the Coronaviridae family and have RNA genomes of 27.9 kb, 30.1 kb, 29.9 kb, and 31.3 kb, respectively [6,12]. Within the viral membrane, the genomic RNA is complexed with the nucleocapsid (N) protein to create a helical capsid. The viral proteins spike (S), envelope (E), and membrane (M) make up the membrane proteins of all CoVs. The S protein is a type I glycoprotein responsible for forming peplomers on the virion surface. The E protein is highly hydrophobic, and the M protein has a cytoplasmic tail that contains a short N-terminal ectodomain ( Figure 1A) [6].
To infect host cells, the S protein on the viral envelope binds to its cellular receptor, which is angiotensin-converting enzyme 2 (ACE2) for SARS-CoV, SARS-CoV-2, and HCoV-NL63; Glossary Acute respiratory distress syndrome (ARDS): type of respiratory failure characterized by the rapid onset of widespread inflammation in the lungs. Caspase-1: inflammatory caspase that is part of the inflammasome and cleaves IL-1β, IL-18, and GSDMD to drive pyroptosis and inflammatory cytokine release. Cytokine storm: over-reaction of the host immune response to release excess amounts of proinflammatory cytokines and chemokines. Gasdermin D (GSDMD): executioner of pyroptosis that has pore-forming activity in the plasma membrane. Inflammasome: multiprotein intracellular complex consisting of caspase-1, ASC, and cytosolic PRRs. Interferon regulatory factor 7 (IRF7): key transcriptional factor of type I IFN production against DNA and RNA viruses. Interferons (IFNs): group of signaling cytokines released by host cells in response to several microbes for antimicrobial defense. Interleukin (IL)-1β: proinflammatory cytokine formed when the pro-IL-1β precursor is cleaved by active caspase-1. Interleukin (IL)-6: proinflammatory cytokine that is active in inflammation and B cell maturation. Interleukin (IL)-18: proinflammatory cytokine formed when the pro-IL-18 precursor is cleaved by active caspase-1. Lactate dehydrogenase (LDH): a common marker of cell death. Mitochondrial antiviral signaling protein (MAVS): signaling protein that binds RLRs during viral infection. Its activation eventually leads to the production of proinflammatory cytokines and type I IFNs.
Mixed lineage kinase domain-like pseudokinase (MLKL): pseudokinase that plays a key role in TNF-induced necroptosis, a programmed cell death process. Necroptosis: MLKL-mediated form of inflammatory cell death. Nuclear factor (NF)-κB: protein complex that regulates cytokine production, cell survival, and transcription of DNA. Oligoadenylate synthetase (OAS)/ RNase L: IFN-induced ribonuclease that destroys both cellular and viral RNA within the cell upon activation. PANoptosis: integrated inflammatory cell death pathway that consists of • IL-6 ↑, TNF ↑, IL-1β ↑ are associated with poor clinical outcomes [11,42,121] Lymphocyte changes
• T helper 17 cells (T H 17) ↑, plasma cells ↑, CD8 + T cell activity ↑, and regulatory T cells ↓ [11,122,123] • Increased neutrophil to lymphocyte ratio predicts disease severity [124], and lymphopenia is associated with use of mechanical ventilation and mortality in severe cases [125,126] • Lymphopenia is mediated with development of acute respiratory distress syndrome (ARDS) [125,126] Thrombocytopenia • Reduced platelet to lymphocyte ratio is associated with worse clinical outcomes [127,128] • Thrombocytopenia is associated with increased risk of severity and in-hospital mortality [127,128] and use of mechanical ventilation and mortality in severe cases [127,128] Ferritin • Increased ferritin is associated with development of ARDS [121,125] and increased risk of death [121] Blood vessels Vasculitis and vascular dysfunction, endothelial cell inflammation and damage cause blood vessels to leak; vascular endothelial growth factor (VEGF) ↑, IL-10 ↑, IL-8 ↑ [11,121,129] Lung Pneumonia with ARDS and dyspnea [10,11,130] Kidneys Acute renal injury resulting in proteinuria and hematuria [131,132] Brain Neurological complications, headache, and ischemic stroke in patients with severe disease [11,133] Heart Acute myocardial injury and chronic damage to cardiovascular system [11,134] Liver Steatosis and abnormal liver function with aspartate transaminase (AST) ↑ and alanine aminotransferase (ALT) ↑ [130,135]; C-reactive protein (CRP) ↑ and albumin ↑ [121,136] Intestine Gastrointestinal symptoms (e.g., diarrhea and severe acute ulcerative colitis) [11,137,138] a ↑, increased concentrations or amounts; ↓ decreased concentrations or amounts.
Trends in Immunology
dipeptidyl peptidase 4 (DPP4) for MERS-CoV; murine carcinoembryonic antigen-related adhesion molecule 1 (mCEACAM1) for MHV; aminopeptidase N (APN) for HCoV-229E; and 9-O-acetylated sialic acid for HCoV-OC43 and HCoV-HKU1 [6,13,14]. S protein binding to these receptors promotes viral and host membrane fusion [6,13,14]. After membrane fusion, the viral RNA genome is released from the endosome into the cytoplasm ( Figure 1B). CoVs have a unique coding strategy, and viral RNA is translated into two large polyproteins, pp1a and pp1ab, encoding 16 nonstructural proteins (nsp1-nsp16) that make up the viral replicasetranscriptase complex [15,16]. This complex generates an antisense negative-strand template; subgenomic negative-strand templates are predicted to enable subgenomic mRNAs to be produced. Membranes derived from the endoplasmic reticulum (ER) and Golgi are reorganized by the viral nonstructural protein (N) to form double-membrane vesicles, where viral replication and transcription occur [17]. The transcribed viral RNAs also encode S, E, M, and N proteins that are not involved in viral replication but mediate virus entry (S) and assembly and release (E and M). To create new virions, newly formed viral proteins traffic to the ER or Golgi membranes, while the genomic RNA and N proteins combine to form nucleocapsids. The full viral particle can then be assembled into the ER-Golgi intermediate compartment (ERGIC). This allows newly synthesized virion-containing vesicles to fuse with the plasma membrane and release the virus [18].
In this review, we discuss innate immune recognition, inflammasome activation, programmed cell death, and cytokine release in response to CoV infections, and describe how innate immune responses regulate disease to contribute to resistance to viral infection and disease tolerance.
Studying the Innate Immune Response to CoVs
Data from patients with CoVs have served as a key starting point for studying these viruses. However, mechanistic dissections of innate immune signaling pathways typically require the use of animal models. Due to species-specific CoV S protein binding to host cellular receptors, there is no single animal model for CoV infection that reproduces all aspects of the human disease. However, adaptation of SARS-CoV (Urbani strain) by serial passage in the lungs of BALB/c mice led to the creation of the MA15 virus, which is lethal following intranasal inoculation in mice [19]. MA15 is used as the mouse model for SARS-CoV, because infection with this virus recapitulates several aspects of the severe human disease, including pulmonary pathology, morbidity, and mortality [19]. For infections with MERS-CoV and SARS-CoV-2, human DPP4 transgenic mice with a mouse-adapted strain of MERS-CoV and human ACE2 (hACE2) transgenic mice with SARS-CoV-2 have been used to replicate several features of severe human disease, including pulmonary pathology and mortality [20,21]. Limitations with these systems have been noted. In human DPP4 transgenic mice, the lung disease that develops in response to the mouse-adapted strain of MERS-CoV infection may depend on species-specific mutations in the new host, which may not recapitulate all aspects of the human infection [20]. A potential disadvantage of studying SARS-CoV-2 in hACE2 transgenic mice is that the brain infection observed in mice that succumb to disease may not reflect the pathogenesis of SARS-CoV-2 in humans [21]. Additionally, hACE2 is expressed under the control of the HFH4/FOXJ1 promoter in these mice, which is largely specific to epithelial cells [21]. Consequently, hematopoietic cells from hACE2 transgenic mice cannot be infected with SARS-CoV-2 [21]. Despite these limitations, significant work has been done to molecularly characterize the innate immune pathways involved in detecting and controlling CoV infections.
Innate Immune Recognition of CoV
The innate immune response acts as a powerful barrier against CoV infection. CoVs infect the host through the oral or nasal cavities, where they first encounter the respiratory epithelium. After infecting respiratory epithelial cells, MHV, SARS-CoV, MERS-CoV, and SARS-CoV-2 can infect both Trends in Immunology non-immune and immune cells in the respiratory tract. During a typical viral infection, viral RNA can be recognized by various PRRs, including TLRs [22,23], RLRs [24,25], and NLRs [26][27][28][29] for the production of proinflammatory cytokines and the induction of an antiviral state ( Figure 2 and Table 2). Prototypically, the proinflammatory cytokines are largely beneficial to the host and trigger the infiltration of immune cells to remove infectious viral agents. However, dysregulated proinflammatory cytokines drive detrimental systemic hyperinflammation and tissue damage [10].
TLR-and RLR-Mediated CoV Recognition TLR-and RLR-mediated signaling lead to the secretion of type I interferons (IFNs), which stimulate the expression of IFN-stimulated genes (ISGs) by infected and neighboring cells, inducing an antiviral state [22,23,25,30]. The TLR-and RLR-signaling cascades also lead to the secretion of proinflammatory cytokines, including interleukin-6 (IL-6) and tumor necrosis factor (TNF) [22,25].
TLR7 is a membrane-bound PRR on endosomes, where it can recognize ssRNA motifs from invading SARS-CoV, MERS-CoV, and MHV [22,23]. After recognizing the ssRNA, TLR7 dimerizes and recruits the myeloid differentiation primary response 88 (MYD88) adaptor protein [10,23,31]. MYD88 recruitment to the endosome results in signaling to trigger transcription factors, including interferon regulatory factor 7 (IRF7) and nuclear factor-κB (NF-κB), which stimulates the production of type I IFNs and proinflammatory cytokines, respectively, for host defense [22,23]. Indeed, Tlr7 -/and Myd88 -/mice have more severe disease following MERS-CoV or MHV infection compared with wild-type (WT) mice, with reduced survival and increased spread of the virus [22,23]. Another membrane-bound PRR, TLR3 has not been found to regulate the expression of type I IFNs and proinflammatory cytokines in response to SARS-CoV and MHV infection because Tlr3 -/mice respond similarly to WT mice [23,32].
Melanoma differentiation-associated gene 5 (MDA5) is a cytosolic PRR in the RLR family that canonically senses double-stranded long RNAs. It plays a role in MHV detection and subsequent type I IFN production [24,25,33]. MDA5 contains two caspase recruitment domain (CARD)-like motifs near its N terminal and a downstream DExD/H-box helicase domain near its C terminal. Upon viral ligand binding in the C terminal domain, MDA5 facilitates conformational changes that enable CARD to bind the signaling adaptor mitochondrial antiviral signaling protein (MAVS), eventually leading to the production of type I IFNs and proinflammatory cytokines via the activation and nuclear translocation of IRF3 and NF-κB [24,25,34].
RIG-I is another cytosolic RLR, and it canonically senses 5′-triphosphate-double-stranded RNA. While RIG-I has been extensively characterized during infection with other respiratory RNA viruses, such as influenza A virus (IAV) [35], the MHV infection-mediated type I IFN response is RIG-I-independent in mice [24]. Further studies are required to determine the dominant innate Type I IFN Response during CoV Infection Different studies have come to opposing conclusions regarding the involvement of the IFN response in CoV infection. In general, type I IFN production is thought to restrict SARS-CoV, MERS-CoV, SARS-CoV-2, and MHV infection in human and murine models [10,22,23,30]. Indeed, mice deficient in key mediators of type I IFN production (Tlr7 -/-, Myd88 -/-, or Mda5 -/mice) show more severe disease following MERS-CoV or MHV infection compared with WT mice; this increased disease severity may be due to the reduced type I IFN production and elevated concentrations of proinflammatory cytokines [10,22,25,31,34]. During infection with SARS-CoV MA15, rapid viral replication in WT mice delays type I IFN signaling but orchestrates a robust proinflammatory cytokine response, including the induction of TNF and IL-6, which promotes lung immunopathology with diminished survival [30]. Ifnar -/mice have reduced morbidity and mortality following lethal SARS-CoV (MA15) infection, suggesting a pathological role for IFN signaling; however, administration of recombinant IFN-β in WT mice early during the SARS-CoV infection reduces the viral titer in the lungs and improves animal survival [30]. Collectively, these results suggest that the timing of the IFN response is crucial and that delayed type I IFN causes lethal pneumonia during SARS-CoV infection [30]. A subsequent study also showed that type I IFN signaling is protective during MERS-CoV infection in the murine model; specifically, relative to control mice, blocking IFN signaling using an anti-IFNAR antibody via intraperitoneal injection led to delayed viral clearance, enhanced neutrophil infiltration, and impaired MERS-CoV-specific CD4 + and CD8 + T cell responses, causing fatal pneumonia [22].
In the case of SARS-CoV-2 infection, data are just beginning to emerge. Single-cell RNA sequencing has shown that the type I IFN response coexists with TNF-and IL-1β-driven inflammation in peripheral blood mononuclear cells (PBMCs) from patients with severe COVID-19, indicating that type I IFN may play a role in exacerbating inflammation in severe COVID-19 [36]. MERS-CoV TLR7 [22] N/A NLRP3 [28] Pyroptosis [28], apoptosis [62,63] IL-1β [28], TNF [28], IL-6 [28] SARS-CoV-2 N/A N/A NLRP3 [42] Pyroptosis [42], apoptosis [65,66] IL-1β [11,38,[40][41][42], IL-18 [42], TNF [11], IL-6 [11] MHV TLR7 [23] MDA5 [24,25,33] NLRP3 [29,52] Pyroptosis [29,52], apoptosis [52,64,139], necroptosis [52] IL-1β [29,52], IL-18 [52], TNF [52], IL-6 [52] a Results are summarized from studies in both humans and mice. b Abbreviations: MDA5, melanoma differentiation-associated protein 5; N/A, not applicable (data for a particular virus and receptor combination have not been reported). chemokines and proinflammatory cytokines, including IL-6, CCL8, CXCL8, CXCL9, CXCL16, IL-1RA, CCL2, CXCL2, EN-RAGE, TNGSF14, and Oncostatin-M, resulting in severe or critical COVID-19 pathology [10,37]. A subsequent study monitoring protein amounts and viral titers in whole blood taken from patients with severe or critical COVID-19 also found that reduced amounts of type I IFNs in the blood during SARS-CoV-2 infection were associated with increased viral load in the blood, and exacerbation of the inflammatory response [38]. Furthermore, data from whole-genome sequencing of patients with life-threatening pneumonia from SARS-CoV-2 infection identified mutations in genes in the type I IFN pathway, such as IRF7, TLR3, and IFNAR1, along with autoantibodies against type I IFNs in the blood, among the patient cohort [39]. Together, these studies suggest that the location, timing, and duration of IFN exposure in both lungs and blood relative to CoV replication are important factors in driving or contributing to infection outcomes, and certainly warrant further investigation.
Trends in Immunology
CoV Infection Stimulates NLRP3 Inflammasome Activation Innate immune cells play a major role in antiviral immunity, inflammatory signaling, and cytokine production. Among the proinflammatory cytokines, IL-1β and IL-18 are key mediators of the inflammatory response, and increased amounts of IL-1β and IL-18 in plasma have been correlated with mortality or severity in patients with COVID-19 [38,[40][41][42]. The release of IL-1β and IL-18 requires proteolytic maturation of pro-IL-1β and pro-IL-18 mediated by inflammasomes and the activation of the protease caspase-1 [43]. The inflammasome sensors can recognize PAMPs and/or DAMPs produced during pathogen infection and cellular instability, respectively [43]. Among those sensors, the most well characterized is the NLR family pyrin domaincontaining 3 (NLRP3), which has been implicated in many diseases, including pathogenmediated disease, autoinflammatory diseases, colitis, and obesity [44][45][46][47][48][49][50].
Studies have shown that SARS-CoV encodes at least three different proteins that can activate NLRP3 inflammasome assembly. First, SARS-CoV open reading frame (ORF) 3a proteinmediated K + efflux and mitochondrial reactive oxygen species (ROS) induce NLRP3 inflammasome activation and IL-1β secretion in lipopolysaccharide (LPS)-primed murine bone marrow-derived macrophages (BMDMs) in vitro [27]. Second, the SARS-CoV ORF8b protein interacts with the LRR domain of NLRP3 and triggers NLRP3 inflammasome activation and IL-1β secretion in THP-1 macrophages [26]. Third, SARS-CoV E protein-mediated ion channel activity induces IL-1β secretion in the bronchoalveolar lavage fluid (BALF) from BALB/c mice [51]. Although the specific ligands from MHV that activate the NLRP3 inflammasome have not been characterized, a recent study demonstrated that MHV infection induces NLRP3 inflammasome activation and the subsequent release of IL-1β and IL-18 in murine BMDMs [52]. In the case of SARS-CoV-2, the specific ligands are also unknown, but infection with the virus can induce NLRP3 inflammasome activation, caspase-1 cleavage, and the release of IL-1β and IL-18 in PBMCs isolated from patients with COVID-19 [42].
Activation of the NLRP3 inflammasome is often vital in the host antiviral immune response [47,48,50]. The NLRP3 inflammasome is activated in response to several RNA viruses, including IAV and West Nile virus (WNV), leading to the inhibition of viral replication and reduced mortality in mouse models [50,53]. However, hyperactivation of the NLRP3 inflammasome can also lead to severe pathological injury. In a murine model of SARS-CoV infection, proinflammatory cytokines, including inflammasome-derived IL-1β, along with TNF and IL-6, promote lung damage and acute respiratory distress syndrome (ARDS) [51]. Additionally, MHV-3 infection induces dysregulated NLRP3 inflammasome activation and IL-1β secretion, resulting in severe liver disease and high mortality in mice [29]. While these studies indicate that optimal NLRP3 inflammasome activation may be beneficial for the host, but that aberrant activation could lead to detrimental outcomes, detailed molecular mechanisms describing how inflammasome-driven inflammation plays a role in ARDS remain largely unknown. Given that IL-1β has been associated with the severity of COVID-19 [38,40,42], future studies are needed to fully examine the factors required for SARS-CoV-2-induced NLRP3 inflammasome assembly and NLRP3 inflammasome-driven ARDS.
Programmed Cell Death and Proinflammatory Cytokines during CoV Infections
Programmed Cell Death Cell death plays an important role in limiting infection with pathogens. However, inflammatory cell death also results in the release of proinflammatory cytokines and cellular contents, including alarmins, PAMPs, and DAMPs, which can cause severe inflammation [54,55]. Therefore, cell death has been considered a double-edged sword for the host during pathogen infection.
Pyroptosis, apoptosis, and necroptosis are mechanistically well-studied programmed cell death pathways (Figure 3, Key Figure).
Pyroptosis during CoV Infection
Pyroptosis is an inflammasome-or gasdermin-mediated form of inflammatory cell death [3]. Inflammasome assembly leads to the activation of inflammatory caspases [caspase-1 (human and mouse), caspase-4 (human), -5 (human), or -11 (mouse)], which proteolytically cleave and release the N-terminal fragment of gasdermin D (GSDMD) to form pores in the plasma membrane [1][2][3]. Caspase-1-dependent GSDMD cleavage leads to the release of IL-1β and IL-18 [1]. SARS-CoV ORF3a, ORF8b, or E protein can induce NLRP3 inflammasome activation and IL-1β secretion, phenomena consistent with pyroptotic death in human THP-1 macrophages and HeLa cells [26,27,51], and pyroptotic death has been directly observed in THP-1 macrophages exposed to SARS-CoV ORF8b [26]. MERS-CoV can also cause pyroptosis and stimulate IL-1β release through the NLRP3 inflammasome in THP-1 cells and hDPP4 transgenic mice [28]. Furthermore, IL-1β release and caspase-1 activation have also been observed in murine peritoneal exudative macrophages (PEMs) and RAW264.7 cells [29]. A recent study revealed that MHV infection induces caspase-1 activation, GSDMD cleavage, IL-1β and IL-18 release, and pyroptosis in murine BMDMs in vitro [52]. Additionally, recent findings suggest that SARS-CoV-2 infection stimulates pyroptosis in PBMCs from patients with COVID-19, as evidenced by NLRP3 inflammasome activation, cleavage of caspase-1, and secretion of IL-1β and IL-18 [42] (Table 2).
Necroptosis during CoV Infection
Necroptosis is a mixed-lineage kinase domain-like pseudokinase (MLKL)-mediated form of inflammatory cell death, during which oligomerized MLKL is translocated and forms channels in the plasma membrane [56]. While evidence for necroptosis during CoV infection has been historically limited, new studies are beginning to identify this cell death pathway in response to CoVs. HCoV-OC43 induces necroptosis in human neural cells [57]. Additionally, a recent study reported that MHV infection induced phosphorylation of MLKL, causing necroptosis in murine BMDMs [52]. This study also found that Nlrp3 -/-, Casp1 -/-Casp11 -/-, or Gsdmd -/-BMDMs exhibited robust apoptosis and necroptosis, as evidenced from the cleavage of caspase-3, -7, and -8 and the phosphorylation of MLKL, driven by caspase-8 and receptor-interacting serine/threonine-protein kinase 3 (RIPK3) during MHV infection; indeed, Casp8 -/-Ripk3 -/-BMDMs were protected from MHV-induced death [52]. To date, there has been no clear evidence of necroptosis in the context of SARS-CoV-2 infection, or SARS-CoV and MERS-CoV (Table 2), and additional work is needed to determine whether this is occurring.
Trends in Immunology
Trends in Immunology, December 2020, Vol. 41
Trends in Immunology
Apoptosis during CoV Infection Pyroptosis and necroptosis are similar in that they are lytic forms of cell death driven by the GSDMD pore and MLKL channel, respectively, which release proinflammatory cytokines and other cellular factors to alert the surrounding cells of danger and to recruit innate and adaptive inflammatory cells [54,55]. Apoptosis was originally thought to be a less inflammatory form of cell death that disassembled the cell via membrane blebbing to avoid directly releasing cellular contents [58]. However, more recent studies have suggested that it is not always immunologically silent, because there is crosstalk between apoptotic proteins and lytic cell death executioners [58]. Apoptosis is driven by initiator caspase-8, -9, and -10 cleavage of executioner caspase-3 and -7. The apoptotic caspase-3 has been reported to activate gasdermin E (GSDME) to induce a lytic form of cell death [59]; caspase-8 has also been reported to activate GSDMD under specific conditions [58]. In the context of CoV infection, SARS-CoV infection and SARS-CoV ORF6 induce apoptosis in Vero E6 cells, indicated by the activation of caspase-3 [60,61]. Likewise, MERS-CoV infection can also activate apoptosis in renal proximal tubular cells (HK2) and human CD4 + and CD8 + T cells isolated from PBMCs, as evidenced by the activation of caspase-3 [62,63]. Additionally, infection with MHV induces apoptosis, as evidenced by cleavage of caspase-3, caspase-7, and caspase-8 in mouse BMDMs [52,64]. ORF3a from SARS-CoV-2 also induces cleavage of caspase-8 and -9 and causes apoptosis in HEK293T, HepG2, and Vero E6 cells [65]. A subsequent study of SARS-CoV-2 infection in human airway epithelial cells in vitro found an increase in cytopathic effects with apoptotic characteristics [66]. Collectively, these findings indicate that CoVs can induce apoptosis (Table 2).
Inflammatory Cell Death and Cytokines
Overt activation of inflammatory cell death pathways may lead to critical tissue damage as well as severe inflammation [54]. For instance, lactate dehydrogenase (LDH), a common marker for cell death, has now been linked to the pathogenesis of COVID-19; specifically, high LDH concentrations in the serum of patients are associated with tissue breakdown during COVID-19, and LDH amounts are considered a powerful predictive factor for the early recognition of lung injury in severe COVID-19 cases [67,68]. Indeed, LDH concentrations are upregulated in PBMCs from patients with COVID-19 [42]. Additionally, autopsy studies have observed lung damage in fatal cases of COVID-19 [69], suggesting that these proinflammatory cell death pathways are dysregulated in severe or critical cases. Because inflammatory cell death releases cytokines and chemokines, this process may contribute to the cytokine storm observed in patients with COVID-19. Patients with severe or critical COVID-19 cases have higher serum concentrations of proinflammatory cytokines and chemokines, such as granulocyte-colony stimulating factor (GCSF), monocyte chemoattractant protein 1 (MCP1), TNF, IL-6, and IL-1β, compared with healthy individuals [11,40]. Recent emerging studies examining the cytokine profiles from patients with COVID-19 have indicated a direct correlation between the cytokine storm and lung injury [70,71]. ARDS is another serious outcome of this cytokine storm [72]. Therefore, it is important to determine what innate immune processes contribute to cytokine release and identify what links may exist between cytokine signaling and inflammatory cell death in SARS-CoV-2 infections.
Additional studies are required to fully elucidate the inflammatory cell death pathways and functional consequences of these processes during CoV infections. Furthermore, based on the death that depends on activation of the protein mixed lineage kinase domain-like pseudokinase (MLKL) to form channels in the membrane. PANoptosis, the coordinated regulation of pyroptosis, apoptosis, and necroptosis, is induced by MHV infection, and IL-1β, IL-18, and alarmins are released through GSDMD and MLKL membrane pores [52,57]. Broken lines represent connections that are known to exist in the context of inflammatory signaling but have not been shown for CoVs specifically. Abbreviations: DAMPs, danger-associated molecular patterns; GSDME, gasdermin E. extensive co-regulation and crosstalk that has been identified between pyroptosis, apoptosis, and necroptosis [73][74][75][76][77][78][79][80][81][82][83], recent work has introduced PANoptosis as a unique inflammatory programmed cell death regulated by the PANoptosome, which provides a molecular scaffold for interactions and activation of the machinery required for inflammasome/pyroptosis, apoptosis, and necroptosis [78,79,82,83]. MHV infection in mice induces PANoptosis in murine BMDMs, and inhibiting activation of the NLRP3 inflammasome pathway and pyroptosis leads to a robust increase in apoptosis and necroptosis, as evidenced by increased cleavage of the apoptotic caspase-3, -7, and -8 and the increased phosphorylation of the necroptotic executioner MLKL in Nlrp3 -/-, Casp1 -/-Casp11 -/-, or Gsdmd -/-BMDMs [52]. It will be important to determine if and how these findings translate to other CoVs, especially SARS-CoV-2, and what the implications of these findings in vivo will be.
CoV Immune Evasion
One of the goals of the innate immune response is to use PRRs to recognize pathogens (here, viral agents) and ultimately trigger an inflammatory response and programmed cell death to limit viral replication and promote clearance. In response, CoVs have undergone selective pressure to limit the innate immune response and permit their intracellular replication [84].
The most well-studied CoV immune evasion mechanism involves counteracting type I IFN innate immune signaling (Figure 2). SARS-CoV ORF3b, ORF6, and N protein can reduce type I IFN expression in A549 cells by inhibiting the activation of IRF3 and NF-κB nuclear translocation [85]. The M protein of SARS-CoV inhibits type I IFN production in HEK293T cells by delaying the formation of a functional TNF receptor-associated factor 3 (TRAF3)-containing complex, which is a key transcription factor that induces IFN production from cells through activation of TBK1 and IKKε upstream of IRF3 [86,87]. SARS-CoV papain-like proteases (PLP) also suppress type I IFN production in HEK293T cells mediated by stimulator of interferon genes (STING) [88]. SARS-CoV nsp1 suppresses type I IFN expression in HEK293T cells by promoting host mRNA degradation [89]. Additionally, MERS-CoV ORF4a suppresses the activation of RIG-I and MDA5 in HEK293T cells [90,91]. MERS-CoV nsp4a and nsp4b can also antagonize IFN expression in human A549 cells stably expressing the MERS-CoV receptor DPP4 [92]. Upon MHV infection, nsp15 and N protein suppress IFN production, as well as protein kinase R (PKR) and 2′,5′-oligoadenylate synthetase (OAS)/RNase L responses in murine 17Cl1 cells or BMDMs [64,93]. MHV nsp2 also antagonizes type I IFN production and blocks the 2′,5′-OAS/RNase L response in BMDMs [94]. Additionally, MHV infection induces high amounts of type I IFN secretion in plasmacytoid dendritic cells (pDCs), BMDMs, microglia, and oligodendrocytes [23,24,95], but relatively little production of type I IFNs in bone marrow-derived dendritic cells (BMDCs), hepatocytes, neurons, astrocytes, and murine 17CI-1 fibroblasts [24,96,97]; this suggests that MHV efficiently evades innate immune sensing in a cell type-dependent manner.
CoV Disease Tolerance versus Immunopathology
Innate host protection can play an important role in dictating CoV disease tolerance. First, SARS-CoV, MERS-CoV, and SARS-CoV-2 disease tolerance can occur in an age-dependent manner, because children with CoV-induced diseases, including COVID-19, have a less aggressive clinical course compared with adults [98][99][100]. However, this may not be due to a virus-specific effect, because children have reduced expression of ACE2 in their nasal epithelium compared with expression in adults [101]; this might result in reduced viral infectivity in children compared with adults and contribute to the age-dependence of SARS-and SARS-CoV-2-induced disease. However, it is important to note that recent studies have found that SARS-CoV-2 infection is sometimes associated with multisystem inflammatory syndrome in children (MIS-C) [102], which is characterized by systemic inflammation, and may be caused by an aberrant immune response, although much remains unknown about this condition, and future robust studies are absolutely necessary.
Second, CoV disease tolerance is species specific. Bats are largely considered the original host of SARS-CoV, MERS-CoV, and SARS-CoV-2 [103][104][105]. NLRP3 inflammasome-mediated inflammation in bat PBMCs is dampened in response to MERS-CoV infection compared with that observed in human PBMCs [106]. Another study also showed that bats have a mutation in an essential and highly conserved serine residue (S358) in STING that causes reduced IFN responses relative to controls in HEK293T cells [107]. These studies suggest that species-dependent host factors and molecular mechanisms regulate inflammatory responses during CoV infection.
Third, CoV disease tolerance is sex dependent. Specifically, men have had a higher case fatality rate than women during the SARS-CoV, MERS-CoV, and SARS-CoV-2 outbreaks [108][109][110][111]. This sex-dependent CoV disease tolerance in women is also more well defined with advancing age [108,110]. One recent study also found that lung infiltration of inflammatory cells and virus titers were further elevated in SARS-CoV-infected male mice compared with female mice and, furthermore, that estrogen receptor signaling induced by tamoxifen enhanced disease tolerance in female mice by moderating SARS-CoV-induced inflammation [112], suggesting that sexbased differences affect inflammation and susceptibility to CoV infection. These results suggest that innate host protection plays an important role in directing CoV disease resistance.
Concluding Remarks
We have highlighted the sensing of different CoVs by the innate immune system and the inflammatory cell death pathways activated in response to these CoV infections. Optimal cell death and inflammatory cytokine release are important for host defense. However, excessive host inflammatory responses and cell death can lead to cytokine storms and/or tissue damage, increasing morbidity and mortality in patients with CoV. Therefore, CoV-induced innate immunity and cell death must be finely controlled to reduce excessive inflammation while retaining antiviral functions.
In this regard, it will be important to mechanistically characterize the innate immune response to different CoV infections and evaluate the clinical efficacy of targeting innate immune pathways when designing evidence-based treatment strategies (see Outstanding Questions). For example, SARS-CoV-2 infection antagonizes type I and type III IFN production, but elevates the expression of chemokines and proinflammatory cytokines [10], which are associated with poor prognosis [10,11]. With other RNA viruses, IAV and WNV, inflammasome activation is required for host defense, but hyperactivation may lead to disease exacerbation [29,50,51,53]. It is possible that reduced innate antiviral defenses together with excessive inflammatory cytokine production are some of the driving features of CoV-mediated diseases.
The SARS-CoV-2 pandemic continues to spread globally, and we now desperately need effective therapies and vaccines to combat COVID-19. Given the urgency of the global health situation, researchers are exploring the possibility of repurposing existing therapeutic agents already approved, or which are under development/testing for other infections, including malaria (Plasmodium sp.), HIV, or other CoVs, or for blockade of the inflammasome (e.g., colchicine) or the proinflammatory cytokines IL-1 and IL-6 [113][114][115][116][117]. The response to these therapies has been mixed. For example, a recent pilot study of COVID-19 in five patients who were already undergoing treatment with colchicine found that all five patients presented with mild/moderate disease and survived despite having multiple comorbidities [118]. However, this was a small observational study, preventing definitive conclusions. Despite promising early data from
Outstanding Questions
What is the dominant signaling pathway that controls the activation of type I IFNs and proinflammatory cytokine expression during CoV infections? What are the molecular mechanisms by which IFN-inducible genes drive robust inflammatory responses with delayed type I IFN production in these infections?
What are the ligands that activate the NLRP3 inflammasome, and what are the key host factors that regulate NLRP3 inflammasome activation in response to SARS-CoV-2 infection?
What types of programmed cell death are induced by CoV infection? Is there any redundancy among these types of cell death? What are the positive/ negative regulators of cell death?
What makes older men more susceptible to CoV-related illness and fatality than other populations? What are the driving forces that lead to gain or loss of NLRP3 inflammasome functions in different species during CoV infections?
Trends in Immunology retrospective and single-center studies using IL-6-antibody blockade therapy [119], recent studies have found that blocking IL-6 can be associated with increased secondary infections [120], and the large Phase III trials using these inhibitors have had mixed results. The first two Phase III randomized double-blind, placebo-controlled trials that included anti-IL-6 antibody and placebo groups in patients with severe COVID-19, the COVACTA (NCT04320615) i and Kevzara trials (NCT04327388) ii , used improvement on the seven category ordinal scale as their primary outcomes. Both reported in company press releases that they failed to meet their primary endpoints. However, EMPACTA (NCT04372186) iii reportedly met its primary endpoint of a reduction in the cumulative proportion of participants requiring mechanical ventilation by day 28, although there was no statistical difference in 28-day mortality between the anti-IL-6 antibody and placebo groups, and the full data have not yet been made available. These results suggest that, while several potential therapies have been explored for COVID-19, balancing proinflammatory responses to clear the virus with preventing systemic inflammation remains challenging. An improved understanding of the mechanisms by which the innate immune system recognizes and responds to specific CoV infections will be key to informing the development of putative therapeutic strategies.
Trends in in Immunology Immunology (See figure legend at the bottom of the next page.)
Figure 1 .Figure 2 .
12Coronavirus (CoV) RNA Genome and Replication. (A) Schematic diagram of representative positive-sense RNA genomes of severe acute respiratory syndrome (SARS)-CoV (29.7 kB), Middle East respiratory syndrome (MERS)-CoV (30.1 kB), SARS-CoV-2 (29.9 kB), and murine hepatitis virus (MHV) (31.3 kB). The -end encodes a polyprotein (ORF1a/b), and the 3′-end encodes four structural proteins [spike (S), membrane (M), envelope (E), nucleocapsid (N)], hemagglutinin-esterase (HE), internal (I) protein, and accessory proteins (ORF2a, 3, 3a, 3b, 4, 4a, 4b, 5a, 5, 6, 7a, 7b, 8a, 8b, 9a, 9b, and/or 10). The S, M, E, and N proteins are unique to each virus. (B) Representative diagram of CoV replication. After host receptor interaction with S viral protein [angiotensin-converting enzyme 2 (ACE2) for SARS-CoV, SARS-CoV-2, and HCoV-NL63; dipeptidyl peptidase 4 (DPP4) for MERS-CoV; murine carcinoembryonic antigen-related adhesion molecule 1 (mCEACAM1) for MHV; aminopeptidase N (APN) for HCoV-229E; 9-O-acetylated sialic acid for HCoV-OC43 and HCoV-HKU1], viral RNA and proteins are released to the cytoplasm, and open reading frame (ORF)-1a and ORF1ab are translated to produce pp1a and pp1ab. Next, pp1a and pp1ab form the replicase-transcriptase complex through cotranslational proteolytic processing. The complex produces an antisense negative-strand template, and the subgenomic mRNAs are synthesized. Subsequent translation of subgenomic mRNAs generates structural viral proteins, including the N, E, M, and S proteins, which are assembled at the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC). Newly synthesized virion-containing vesicles fuse with the plasma membrane to release the virus [15-18]. ACE2, angiotensin-converting enzyme 2; APN, aminopeptidase N; CoV, coronavirus; DPP4, dipeptidyl peptidase 4; mCEACAM1, murine carcinoembryonic antigen-related adhesion molecule 1; ORF, open reading frame. Innate Immune-Sensing Pathways in Coronavirus (CoV) Infection and Immune Evasion. Upon CoV infection, incoming double-stranded RNA (dsRNA) and genomic single-stranded RNA (ssRNA) are recognized by Toll-like receptor 3 (TLR3) and TLR7, respectively. Signaling downstream of these TLRs induces activation of nuclear factor-κB (NF-κB) to produce proinflammatory cytokines and phosphorylation of interferon regulatory factor 3 (IRF3) and IRF7 to drive type I interferon (IFN) (Figure legend continued at the bottom of the next page.) Trends in Immunology sensor that drives type I IFN induction in vivo in response to infection with different CoVs (see Outstanding Questions).
Conversely, recent reports have observed that low amounts of type I and type III IFN proteins in the serum of patients with COVID-19 are accompanied by elevated protein amounts of production. Viral RNA in the cytosol is recognized by retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5). The helicases of RIG-I and MDA5 associate with mitochondrial antiviral signaling protein (MAVS), leading to the activation of NF-κB and phosphorylation of IRF3. Severe acute respiratory syndrome (SARS)-CoV open reading frame (ORF)-3a, ORF8b, and envelope (E) protein stimulate the inflammasome, which results in caspase-1 activation and release of the cytokines interleukin-1β (IL-1β) and IL-18. Many CoV viral proteins [red: SARS-CoV, blue: Middle East respiratory syndrome (MERS)-CoV, green: murine hepatitis virus (MHV)] antagonize type I IFN signaling [85-91]. Abbreviations: ASC, apoptosis-associated speck-like protein containing a caspase activation domain; M, membrane protein; N, nucleocapsid protein; NLRP3, nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3; nsp, nonstructural protein; PLP, papain-like protease.
Figure 3 .
3Upon severe acute respiratory syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)-CoV, SARS-CoV-2, and murine hepatitis virus (MHV) infection, CoV viral proteins can function as cytosolic pathogen-associated molecular patterns (PAMPs) and stimulate inflammasome assembly, resulting in activation of caspase-1. Active caspase-1 then cleaves pro-interleukin (IL)-1β, pro-IL-18, and gasdermin D (GSDMD). The N-terminal fragment of GSDMD may then oligomerize within membranes to form membrane pores and execute pyroptosis [26-29,42,51,52]. SARS-CoV, MERS-CoV, SARS-CoV-2, and MHV infections also initiate a signaling cascade mediated by caspase-8 activation. Caspase-8 activates caspase-3 to drive apoptosis [52,60-66]. Human (H)CoV-OC43 and MHV infection initiate necroptosis, a receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and RIPK3 complex-dependent form of inflammatory cell (Figure legend continued at the bottom of the next page.)
Table 1 .
1Systemic Hyperinflammation and Tissue Damage during SARS-CoV-2 Infection in Humans aOrgan/system
Symptoms and clinical outcome
Circulation
Cytokine storm
Table 2 .
2Engaged Innate Immune Sensors, Subsequent Cell Death Pathways, and Notable Cytokines Released in Response to Specific CoVs a,bVirus
TLRs
RLRs
NLRs
Cell death
Notable cytokines
SARS-CoV
TLR7
[22]
N/A
NLRP3
[26,27,51]
Pyroptosis [26,27,51], apoptosis [60,61]
IL-1β [26,27,51], TNF [51], IL-6 [51]
Trends in Immunology, December 2020, Vol. 41, No. 12
Trends in Immunology, December 2020, Vol. 41, No. 12
Trends in Immunology, December 2020, Vol. 41, No. 12
Trends in Immunology, December 2020, Vol. 41, No. 12
AcknowledgmentsWe apologize to our colleagues in the field whose work could not be cited due to space limitations. We thank all the members
Molecular mechanisms and functions of pyroptosis, inflammatory caspases and inflammasomes in infectious diseases. S M Man, Immunol. Rev. 277Man, S.M. et al. (2017) Molecular mechanisms and functions of pyroptosis, inflammatory caspases and inflammasomes in infectious diseases. Immunol. Rev. 277, 61-75
Gasdermin D is an executor of pyroptosis and required for interleukin-1beta secretion. W T He, Cell Res. 25He, W.T. et al. (2015) Gasdermin D is an executor of pyroptosis and required for interleukin-1beta secretion. Cell Res. 25, 1285-1298
Cleavage of GSDMD by inflammatory caspases determines pyroptotic cell death. J Shi, Nature. 526Shi, J. et al. (2015) Cleavage of GSDMD by inflammatory caspases determines pyroptotic cell death. Nature 526, 660-665
Points of control in inflammation. C Nathan, Nature. 420Nathan, C. (2002) Points of control in inflammation. Nature 420, 846-852
Bat origin of human coronaviruses. B Hu, Virol. J. 12221Hu, B. et al. (2015) Bat origin of human coronaviruses. Virol. J. 12, 221
Coronaviruses: an overview of their replication and pathogenesis. A R Fehr, S Perlman, Methods Mol. Biol. 1282Fehr, A.R. and Perlman, S. (2015) Coronaviruses: an overview of their replication and pathogenesis. Methods Mol. Biol. 1282, 1-23
A pneumonia outbreak associated with a new coronavirus of probable bat origin. P Zhou, Nature. 579Zhou, P. et al. (2020) A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature 579, 270-273
Epidemiology and cause of severe acute respiratory syndrome (SARS) in Guangdong, People's Republic of China. N S Zhong, Lancet. 362Zhong, N.S. et al. (2003) Epidemiology and cause of severe acute respiratory syndrome (SARS) in Guangdong, People's Republic of China, in February, 2003. Lancet 362, 1353-1358
Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. A M Zaki, N. Engl. J. Med. 367Zaki, A.M. et al. (2012) Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N. Engl. J. Med. 367, 1814-1820
Imbalanced host response to SARS-CoV-2 drives development of COVID-19. D Blanco-Melo, Cell. 181Blanco-Melo, D. et al. (2020) Imbalanced host response to SARS-CoV-2 drives development of COVID-19. Cell 181, 1036-1045.e1039
Clinical features of patients infected with 2019 novel coronavirus in Wuhan. C Huang, China. Lancet. 395Huang, C. et al. (2020) Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 395, 497-506
The architecture of SARS-CoV-2 transcriptome. D Kim, Cell. 181Kim, D. et al. (2020) The architecture of SARS-CoV-2 transcriptome. Cell 181, 914-921
Angiotensin-converting enzyme 2 is a functional receptor for the SARS coronavirus. W Li, Nature. 426Li, W. et al. (2003) Angiotensin-converting enzyme 2 is a func- tional receptor for the SARS coronavirus. Nature 426, 450-454
SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease inhibitor. M Hoffmann, Cell. 181Hoffmann, M. et al. (2020) SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease inhibitor. Cell 181, 271-280
A contemporary view of coronavirus transcription. S G Sawicki, J. Virol. 81Sawicki, S.G. et al. (2007) A contemporary view of coronavirus transcription. J. Virol. 81, 20-29
Mechanisms and enzymes involved in SARS coronavirus genome expression. V Thiel, J. Gen. Virol. 84Thiel, V. et al. (2003) Mechanisms and enzymes involved in SARS coronavirus genome expression. J. Gen. Virol. 84, 2305-2315
SARS-coronavirus replication is supported by a reticulovesicular network of modified endoplasmic reticulum. K Knoops, PLoS Biol. 6226Knoops, K. et al. (2008) SARS-coronavirus replication is sup- ported by a reticulovesicular network of modified endoplasmic reticulum. PLoS Biol. 6, e226
SARS and MERS: recent insights into emerging coronaviruses. E De Wit, Nat. Rev. Microbiol. 14de Wit, E. et al. (2016) SARS and MERS: recent insights into emerging coronaviruses. Nat. Rev. Microbiol. 14, 523-534
A mouse-adapted SARS-coronavirus causes disease and mortality in BALB/c mice. A Roberts, PLoS Pathog. 35Roberts, A. et al. (2007) A mouse-adapted SARS-coronavirus causes disease and mortality in BALB/c mice. PLoS Pathog. 3, e5
Mouse-adapted MERS coronavirus causes lethal lung disease in human DPP4 knockin mice. K Li, Proc. Natl. Acad. Sci. U. S. A. 114Li, K. et al. (2017) Mouse-adapted MERS coronavirus causes lethal lung disease in human DPP4 knockin mice. Proc. Natl. Acad. Sci. U. S. A. 114, E3119-E3128
Pathogenesis of SARS-CoV-2 in transgenic mice expressing human angiotensin-converting enzyme 2. R D Jiang, Cell. 182Jiang, R.D. et al. (2020) Pathogenesis of SARS-CoV-2 in trans- genic mice expressing human angiotensin-converting enzyme 2. Cell 182, 50-58
IFN-I response timing relative to virus replication determines MERS coronavirus infection outcomes. R Channappanavar, J. Clin. Invest. 130Channappanavar, R. et al. (2019) IFN-I response timing relative to virus replication determines MERS coronavirus infection outcomes. J. Clin. Invest. 130, 3625-3639
Control of coronavirus infection through plasmacytoid dendritic-cell-derived type I interferon. L Cervantes-Barragan, Blood. 109Cervantes-Barragan, L. et al. (2007) Control of coronavirus infection through plasmacytoid dendritic-cell-derived type I interferon. Blood 109, 1131-1137
Murine coronavirus mouse hepatitis virus is recognized by MDA5 and induces type I interferon in brain macrophages/microglia. J K Roth-Cross, J. Virol. 82Roth-Cross, J.K. et al. (2008) Murine coronavirus mouse hepatitis virus is recognized by MDA5 and induces type I inter- feron in brain macrophages/microglia. J. Virol. 82, 9829-9838
MDA5 is critical to host defense during infection with murine coronavirus. Z B Zalinger, J. Virol. 89Zalinger, Z.B. et al. (2015) MDA5 is critical to host defense during infection with murine coronavirus. J. Virol. 89, 12330-12340
SARS-coronavirus open reading frame-8b triggers intracellular stress pathways and activates NLRP3 inflammasomes. C S Shi, Cell Death Discov. 5101Shi, C.S. et al. (2019) SARS-coronavirus open reading frame- 8b triggers intracellular stress pathways and activates NLRP3 inflammasomes. Cell Death Discov. 5, 101
Severe acute respiratory syndrome coronavirus viroporin 3a activates the NLRP3 inflammasome. I Y Chen, Front. Microbiol. 1050Chen, I.Y. et al. (2019) Severe acute respiratory syndrome coronavirus viroporin 3a activates the NLRP3 inflammasome. Front. Microbiol. 10, 50
Complement receptor C5aR1 inhibition reduces pyroptosis in hDPP4-transgenic mice infected with MERS-CoV. Y Jiang, Viruses. 11Jiang, Y. et al. (2019) Complement receptor C5aR1 inhibition reduces pyroptosis in hDPP4-transgenic mice infected with MERS-CoV. Viruses 11
The NLRP3 inflammasome and IL-1β accelerate immunologically mediated pathology in experimental viral fulminant hepatitis. S Guo, PLoS Pathog. 111005155Guo, S. et al. (2015) The NLRP3 inflammasome and IL-1β ac- celerate immunologically mediated pathology in experimental viral fulminant hepatitis. PLoS Pathog. 11, e1005155
Dysregulated Type I interferon and inflammatory monocyte-macrophage responses cause lethal pneumonia in SARS-CoV-infected mice. R Channappanavar, Cell Host Microbe. 19Channappanavar, R. et al. (2016) Dysregulated Type I inter- feron and inflammatory monocyte-macrophage responses cause lethal pneumonia in SARS-CoV-infected mice. Cell Host Microbe 19, 181-193
MyD88 is required for protection from lethal infection with a mouse-adapted SARS-CoV. T Sheahan, PLoS Pathog. 41000240Sheahan, T. et al. (2008) MyD88 is required for protection from lethal infection with a mouse-adapted SARS-CoV. PLoS Pathog. 4, e1000240
Toll-like receptor 3 signaling via TRIF contributes to a protective innate immune response to severe acute respiratory syndrome coronavirus infection. A L Totura, 6Totura, A.L. et al. (2015) Toll-like receptor 3 signaling via TRIF contributes to a protective innate immune response to severe acute respiratory syndrome coronavirus infection. mBio 6, e00638-00615
Coronavirus endoribonuclease targets viral polyuridine sequences to evade activating host sensors. M Hackbart, Proc. Natl. Acad. Sci. U. S. A. 117Hackbart, M. et al. (2020) Coronavirus endoribonuclease tar- gets viral polyuridine sequences to evade activating host sen- sors. Proc. Natl. Acad. Sci. U. S. A. 117, 8094-8103
Rapid generation of a mouse model for Middle East respiratory syndrome. J Zhao, Proc. Natl. Acad. Sci. U. S. A. 111Zhao, J. et al. (2014) Rapid generation of a mouse model for Middle East respiratory syndrome. Proc. Natl. Acad. Sci. U. S. A. 111, 4970-4975
RIG-I-mediated antiviral responses to single-stranded RNA bearing 5'-phosphates. A Pichlmair, Science. 314Pichlmair, A. et al. (2006) RIG-I-mediated antiviral responses to single-stranded RNA bearing 5'-phosphates. Science 314, 997-1001
Immunophenotyping of COVID-19 and influenza highlights the role of type I interferons in development of severe COVID-19. J S Lee, Sci. Immunol. 51554Lee, J.S. et al. (2020) Immunophenotyping of COVID-19 and influenza highlights the role of type I interferons in development of severe COVID-19. Sci. Immunol. 5, eabd1554
Systems biological assessment of immunity to mild versus severe COVID-19 infection in humans. P S Arunachalam, Science. 369Arunachalam, P.S. et al. (2020) Systems biological assessment of immunity to mild versus severe COVID-19 infection in humans. Science 369, 1210-1220
Impaired type I interferon activity and inflammatory responses in severe COVID-19 patients. J Hadjadj, Science. 369Hadjadj, J. et al. (2020) Impaired type I interferon activity and inflammatory responses in severe COVID-19 patients. Science 369, 718-724
Inborn errors of type I IFN immunity in patients with life-threatening COVID-19. Q Zhang, Lancet Rheumatol. 40ScienceZhang, Q. et al. (2020) Inborn errors of type I IFN immunity in patients with life-threatening COVID-19. Science 40. King, A. et al. (2020) Anakinra in COVID-19: important considerations for clinical trials. Lancet Rheumatol. 2, e379-e381
Interleukin-1 blockade with high-dose anakinra in patients with COVID-19, acute respiratory distress syndrome, and hyperinflammation: a retrospective cohort study. G Cavalli, Lancet Rheumatol. 2Cavalli, G. et al. (2020) Interleukin-1 blockade with high-dose anakinra in patients with COVID-19, acute respiratory distress syndrome, and hyperinflammation: a retrospective cohort study. Lancet Rheumatol. 2, e325-e331
Inflammasome activation in COVID-19 patients. medRxiv. T S Rodrigues, 10.1101/2020.08.05.20168872Published onlineRodrigues, T.S. et al. (2020) Inflammasome activation in COVID-19 patients. medRxiv. Published online August 6, 2020. https://doi.org/10.1101/2020.08.05.20168872
Central roles of NLRs and inflammasomes in viral infection. T D Kanneganti, Nat. Rev. Immunol. 10Kanneganti, T.D. (2010) Central roles of NLRs and inflammasomes in viral infection. Nat. Rev. Immunol. 10, 688-698
Autoinflammatory skin disorders: the inflammasomme in focus. P Gurung, T D Kanneganti, Trends Mol. Med. 22Gurung, P. and Kanneganti, T.D. (2016) Autoinflammatory skin disorders: the inflammasomme in focus. Trends Mol. Med. 22, 545-564
The NLRP3 inflammasome protects against loss of epithelial integrity and mortality during experimental colitis. M H Zaki, Immunity. 32Zaki, M.H. et al. (2010) The NLRP3 inflammasome protects against loss of epithelial integrity and mortality during experi- mental colitis. Immunity 32, 379-391
Inflammasome is a central player in the induction of obesity and insulin resistance. R Stienstra, Proc. Natl. Acad. Sci. U. S. A. 108Stienstra, R. et al. (2011) Inflammasome is a central player in the induction of obesity and insulin resistance. Proc. Natl. Acad. Sci. U. S. A. 108, 15324-15329
Bacterial RNA and small antiviral compounds activate caspase-1 through cryopyrin/Nalp3. T D Kanneganti, Nature. 440Kanneganti, T.D. et al. (2006) Bacterial RNA and small antiviral compounds activate caspase-1 through cryopyrin/Nalp3. Nature 440, 233-236
Critical role for Cryopyrin/Nalp3 in activation of caspase-1 in response to viral infection and double-stranded RNA. T D Kanneganti, J. Biol. Chem. 281Kanneganti, T.D. et al. (2006) Critical role for Cryopyrin/Nalp3 in activation of caspase-1 in response to viral infection and double-stranded RNA. J. Biol. Chem. 281, 36560-36568
Concerted activation of the AIM2 and NLRP3 inflammasomes orchestrates host protection against Aspergillus infection. R Karki, Cell Host Microbe. 17Karki, R. et al. (2015) Concerted activation of the AIM2 and NLRP3 inflammasomes orchestrates host protection against Aspergillus infection. Cell Host Microbe 17, 357-368
The intracellular sensor NLRP3 mediates key innate and healing responses to influenza A virus via the regulation of caspase-1. P G Thomas, Immunity. 30Thomas, P.G. et al. (2009) The intracellular sensor NLRP3 me- diates key innate and healing responses to influenza A virus via the regulation of caspase-1. Immunity 30, 566-575
Severe acute respiratory syndrome coronavirus envelope protein ion channel activity promotes virus fitness and pathogenesis. J L Nieto-Torres, PLoS Pathog. 101004077Nieto-Torres, J.L. et al. (2014) Severe acute respiratory syndrome coronavirus envelope protein ion channel activity promotes virus fitness and pathogenesis. PLoS Pathog. 10, e1004077
Impaired NLRP3 inflammasome activation/pyroptosis leads to robust inflammatory cell death via caspase-8/RIPK3 during coronavirus infection. M Zheng, 10.1074/jbc.RA120.015036J. Biol. Chem. Published onlineZheng, M. et al. (2020) Impaired NLRP3 inflammasome activation/pyroptosis leads to robust inflammatory cell death via caspase-8/RIPK3 during coronavirus infection. J. Biol. Chem. Published online August 6, 2020. https://doi.org/ 10.1074/jbc.RA120.015036
IL-1β signaling promotes CNSintrinsic immune control of West Nile virus infection. H J Ramos, PLoS Pathog. 81003039Ramos, H.J. et al. (2012) IL-1β signaling promotes CNS- intrinsic immune control of West Nile virus infection. PLoS Pathog. 8, e1003039
Pyroptosis: host cell death and inflammation. T Bergsbaken, Nat. Rev. Microbiol. 7Bergsbaken, T. et al. (2009) Pyroptosis: host cell death and in- flammation. Nat. Rev. Microbiol. 7, 99-109
Necroptosis and its role in inflammation. M Pasparakis, P Vandenabeele, Nature. 517Pasparakis, M. and Vandenabeele, P. (2015) Necroptosis and its role in inflammation. Nature 517, 311-320
MLKL compromises plasma membrane integrity by binding to phosphatidylinositol phosphates. Y Dondelinger, Cell Rep. 7Dondelinger, Y. et al. (2014) MLKL compromises plasma mem- brane integrity by binding to phosphatidylinositol phosphates. Cell Rep. 7, 971-981
Pivotal role of receptorinteracting protein kinase 1 and mixed lineage kinase domainlike in neuronal cell death induced by the human neuroinvasive coronavirus OC43. M Meessen-Pinard, J. Virol. 91Meessen-Pinard, M. et al. (2017) Pivotal role of receptor- interacting protein kinase 1 and mixed lineage kinase domain- like in neuronal cell death induced by the human neuroinvasive coronavirus OC43. J. Virol. 91, e01513-16
PANoptosis in microbial infection. D E Place, Curr. Opin. Microbiol. 59Place, D.E. et al. (2020) PANoptosis in microbial infection. Curr. Opin. Microbiol. 59, 42-49
Gasdermin pores permeabilize mitochondria to augment caspase-3 activation during apoptosis and inflammasome activation. C Rogers, Nat. Commun. 101689Rogers, C. et al. (2019) Gasdermin pores permeabilize mito- chondria to augment caspase-3 activation during apoptosis and inflammasome activation. Nat. Commun. 10, 1689
Apoptosis induced by the SARSassociated coronavirus in Vero cells is replication-dependent and involves caspase. L Ren, DNA Cell Biol. 24Ren, L. et al. (2005) Apoptosis induced by the SARS- associated coronavirus in Vero cells is replication-dependent and involves caspase. DNA Cell Biol. 24, 496-502
A SARS-CoV protein, ORF-6, induces caspase-3 mediated, ER stress and JNK-dependent apoptosis. Z Ye, Biochim. Biophys. Acta. 1780Ye, Z. et al. (2008) A SARS-CoV protein, ORF-6, induces caspase-3 mediated, ER stress and JNK-dependent apopto- sis. Biochim. Biophys. Acta 1780, 1383-1387
MERS coronavirus induces apoptosis in kidney and lung by upregulating Smad7 and FGF2. M L Yeung, Nat. Microbiol. 116004Yeung, M.L. et al. (2016) MERS coronavirus induces apoptosis in kidney and lung by upregulating Smad7 and FGF2. Nat. Microbiol. 1, 16004
Middle East respiratory syndrome coronavirus efficiently infects human primary T lymphocytes and activates the extrinsic and intrinsic apoptosis pathways. H Chu, J. Infect. Dis. 213Chu, H. et al. (2016) Middle East respiratory syndrome corona- virus efficiently infects human primary T lymphocytes and acti- vates the extrinsic and intrinsic apoptosis pathways. J. Infect. Dis. 213, 904-914
Coronavirus nonstructural protein 15 mediates evasion of dsRNA sensors and limits apoptosis in macrophages. X Deng, Proc. Natl. Acad. Sci. U. S. A. 114Deng, X. et al. (2017) Coronavirus nonstructural protein 15 me- diates evasion of dsRNA sensors and limits apoptosis in mac- rophages. Proc. Natl. Acad. Sci. U. S. A. 114, E4251-E4260
The ORF3a protein of SARS-CoV-2 induces apoptosis in cells. Y Ren, Cell. Mol. Immunol. 17Ren, Y. et al. (2020) The ORF3a protein of SARS-CoV-2 in- duces apoptosis in cells. Cell. Mol. Immunol. 17, 881-883
Morphogenesis and cytopathic effect of SARS-CoV-2 infection in human airway epithelial cells. N Zhu, Nat. Commun. 113910Zhu, N. et al. (2020) Morphogenesis and cytopathic effect of SARS-CoV-2 infection in human airway epithelial cells. Nat. Commun. 11, 3910
An interpretable mortality prediction model for COVID-19 patients. L Yan, Nat. Mach. Intell. 2Yan, L. et al. (2020) An interpretable mortality prediction model for COVID-19 patients. Nat. Mach. Intell. 2, 283-288
Consider laboratory aspects in developing patient prediction models. J L V Reeve, P J Twomey, 10.1038/s42256-020-0221-2Nat. Mach. Intell. 12Published online AugustReeve, J.L.V. and Twomey, P.J. (2020) Consider laboratory aspects in developing patient prediction models. Nat. Mach. Intell. Published online August 12, 2020. https://doi.org/ 10.1038/s42256-020-0221-2
Pulmonary post-mortem findings in a series of COVID-19 cases from northern Italy: a two-centre descriptive study. L Carsana, 10.1016/S1473-3099(20)30434-5Lancet Infect. Dis. Published onlineCarsana, L. et al. (2020) Pulmonary post-mortem findings in a series of COVID-19 cases from northern Italy: a two-centre de- scriptive study. Lancet Infect. Dis. Published online June 8, 2020. https://doi.org/10.1016/S1473-3099(20)30434-5
COVID-19 cytokine storm: the interplay between inflammation and coagulation. R J Jose, A Manuel, Lancet Respir. Med. 8Jose, R.J. and Manuel, A. (2020) COVID-19 cytokine storm: the interplay between inflammation and coagulation. Lancet Respir. Med. 8, e46-e47
COVID-19: consider cytokine storm syndromes and immunosuppression. P Mehta, Lancet. 395Mehta, P. et al. (2020) COVID-19: consider cytokine storm syn- dromes and immunosuppression. Lancet 395, 1033-1034
The COVID-19 cytokine storm; what we know so far. D Ragab, Front. Immunol. 111446Ragab, D. et al. (2020) The COVID-19 cytokine storm; what we know so far. Front. Immunol. 11, 1446
Targeted peptidecentric proteomics reveals caspase-7 as a substrate of the caspase-1 inflammasomes. M Lamkanfi, Mol. Cell. Proteomics. 7Lamkanfi, M. et al. (2008) Targeted peptidecentric proteo- mics reveals caspase-7 as a substrate of the caspase-1 inflammasomes. Mol. Cell. Proteomics 7, 2350-2363
Cutting edge: proteolytic inactivation of poly(ADP-ribose) polymerase 1 by the Nlrp3 and Nlrc4 inflammasomes. R K Malireddi, J. Immunol. 185Malireddi, R.K. et al. (2010) Cutting edge: proteolytic inactiva- tion of poly(ADP-ribose) polymerase 1 by the Nlrp3 and Nlrc4 inflammasomes. J. Immunol. 185, 3127-3130
FADD and caspase-8 mediate priming and activation of the canonical and noncanonical Nlrp3 inflammasomes. P Gurung, J. Immunol. 192Gurung, P. et al. (2014) FADD and caspase-8 mediate priming and activation of the canonical and noncanonical Nlrp3 inflammasomes. J. Immunol. 192, 1835-1846
Critical role for inflammasomeindependent IL-1β production in osteomyelitis. J R Lukens, Proc. Natl. Acad. Sci. U. S. A. 111Lukens, J.R. et al. (2014) Critical role for inflammasome- independent IL-1β production in osteomyelitis. Proc. Natl. Acad. Sci. U. S. A. 111, 1066-1071
NLRP3 inflammasome plays a redundant role with caspase 8 to promote IL-1β-mediated osteomyelitis. P Gurung, Proc. Natl. Acad. Sci. U. S. A. 113Gurung, P. et al. (2016) NLRP3 inflammasome plays a redundant role with caspase 8 to promote IL-1β-mediated osteomyelitis. Proc. Natl. Acad. Sci. U. S. A. 113, 4452-4457
Caspase-6 is a key regulator of innate immunity, inflammasome activation, and host defense. M Zheng, Cell. 181e613Zheng, M. et al. (2020) Caspase-6 is a key regulator of innate immunity, inflammasome activation, and host defense. Cell 181, 674-687.e613
Identification of the PANoptosome: a molecular platform triggering pyroptosis, apoptosis, and necroptosis (PANoptosis). Front. S Christgen, Cell. Infect. Microbiol. 10237Christgen, S. et al. (2020) Identification of the PANoptosome: a molecular platform triggering pyroptosis, apoptosis, and necroptosis (PANoptosis). Front. Cell. Infect. Microbiol. 10, 237
ZBP1/DAI is an innate sensor of influenza virus triggering the NLRP3 inflammasome and programmed cell death pathways. T Kuriakose, Sci. Immunol. 12045Kuriakose, T. et al. (2016) ZBP1/DAI is an innate sensor of in- fluenza virus triggering the NLRP3 inflammasome and pro- grammed cell death pathways. Sci. Immunol. 1, aag2045
ZBP1/DAI ubiquitination and sensing of influenza vRNPs activate programmed cell death. S Kesavardhana, J. Exp. Med. 214Kesavardhana, S. et al. (2017) ZBP1/DAI ubiquitination and sensing of influenza vRNPs activate programmed cell death. J. Exp. Med. 214, 2217-2229
ZBP1 and TAK1: master regulators of NLRP3 inflammasome/pyroptosis, apoptosis, and necroptosis (PAN-optosis). R K S Malireddi, Front. Cell. Infect. Microbiol. 9406Malireddi, R.K.S. et al. (2019) ZBP1 and TAK1: master regula- tors of NLRP3 inflammasome/pyroptosis, apoptosis, and necroptosis (PAN-optosis). Front. Cell. Infect. Microbiol. 9, 406
The PANoptosome: a deadly protein complex driving pyroptosis, apoptosis, and necroptosis (PANoptosis). Front. P Samir, Cell. Infect. Microbiol. 10238Samir, P. et al. (2020) The PANoptosome: a deadly protein complex driving pyroptosis, apoptosis, and necroptosis (PANoptosis). Front. Cell. Infect. Microbiol. 10, 238
Coronaviruses post-SARS: update on replication and pathogenesis. S Perlman, J Netland, Nat. Rev. Microbiol. 7Perlman, S. and Netland, J. (2009) Coronaviruses post-SARS: update on replication and pathogenesis. Nat. Rev. Microbiol. 7, 439-450
Severe acute respiratory syndrome coronavirus open reading frame (ORF) 3b, ORF 6, and nucleocapsid proteins function as interferon antagonists. S A Kopecky-Bromberg, J. Virol. 81Kopecky-Bromberg, S.A. et al. (2007) Severe acute respiratory syndrome coronavirus open reading frame (ORF) 3b, ORF 6, and nucleocapsid proteins function as interferon antagonists. J. Virol. 81, 548-557
Severe acute respiratory syndrome coronavirus M protein inhibits type I interferon production by impeding the formation of TRAF3.TANK.TBK1/IKKepsilon complex. K L Siu, J. Biol. Chem. 284Siu, K.L. et al. (2009) Severe acute respiratory syndrome coro- navirus M protein inhibits type I interferon production by imped- ing the formation of TRAF3.TANK.TBK1/IKKepsilon complex. J. Biol. Chem. 284, 16202-16209
Specificity in Toll-like receptor signalling through distinct effector functions of TRAF3 and TRAF6. H Häcker, Nature. 439Häcker, H. et al. (2006) Specificity in Toll-like receptor signalling through distinct effector functions of TRAF3 and TRAF6. Nature 439, 204-207
Coronavirus papain-like proteases negatively regulate antiviral innate immune response through disruption of STING-mediated signaling. L Sun, PLoS ONE. 730802Sun, L. et al. (2012) Coronavirus papain-like proteases nega- tively regulate antiviral innate immune response through disrup- tion of STING-mediated signaling. PLoS ONE 7, e30802
Severe acute respiratory syndrome coronavirus nsp1 suppresses host gene expression, including that of type I interferon, in infected cells. K Narayanan, J. Virol. 82Narayanan, K. et al. (2008) Severe acute respiratory syndrome coronavirus nsp1 suppresses host gene expression, including that of type I interferon, in infected cells. J. Virol. 82, 4471-4479
Middle east respiratory syndrome coronavirus 4a protein is a double-stranded RNA-binding protein that suppresses PACT-induced activation of RIG-I and MDA5 in the innate antiviral response. K L Siu, J. Virol. 88Siu, K.L. et al. (2014) Middle east respiratory syndrome coro- navirus 4a protein is a double-stranded RNA-binding protein that suppresses PACT-induced activation of RIG-I and MDA5 in the innate antiviral response. J. Virol. 88, 4866-4876
Middle East respiratory syndrome coronavirus accessory protein 4a is a type I interferon antagonist. D Niemeyer, J. Virol. 87Niemeyer, D. et al. (2013) Middle East respiratory syndrome coronavirus accessory protein 4a is a type I interferon antago- nist. J. Virol. 87, 12489-12495
Antagonism of dsRNA-induced innate immune pathways by NS4a and NS4b accessory proteins during MERS coronavirus infection. C E Comar, 10Comar, C.E. et al. (2019) Antagonism of dsRNA-induced in- nate immune pathways by NS4a and NS4b accessory proteins during MERS coronavirus infection. mBio 10, e00319-19
Mouse hepatitis coronavirus A59 nucleocapsid protein is a type I interferon antagonist. Y Ye, J. Virol. 81Ye, Y. et al. (2007) Mouse hepatitis coronavirus A59 nucleo- capsid protein is a type I interferon antagonist. J. Virol. 81, 2554-2563
Antagonism of the interferon-induced OAS-RNase L pathway by murine coronavirus ns2 protein is required for virus replication and liver pathology. L Zhao, Cell Host Microbe. 11Zhao, L. et al. (2012) Antagonism of the interferon-induced OAS-RNase L pathway by murine coronavirus ns2 protein is required for virus replication and liver pathology. Cell Host Microbe 11, 607-616
Murine coronavirus induces type I interferon in oligodendrocytes through recognition by RIG-I and MDA5. J Li, J. Virol. 84Li, J. et al. (2010) Murine coronavirus induces type I interferon in oligodendrocytes through recognition by RIG-I and MDA5. J. Virol. 84, 6472-6482
Preferential infection of mature dendritic cells by mouse hepatitis virus strain JHM. H Zhou, S Perlman, J. Virol. 80Zhou, H. and Perlman, S. (2006) Preferential infection of mature dendritic cells by mouse hepatitis virus strain JHM. J. Virol. 80, 2506-2514
Mouse hepatitis virus does not induce Beta interferon synthesis and does not inhibit its induction by double-stranded RNA. H Zhou, S Perlman, J. Virol. 81Zhou, H. and Perlman, S. (2007) Mouse hepatitis virus does not induce Beta interferon synthesis and does not inhibit its in- duction by double-stranded RNA. J. Virol. 81, 568-574
Clinical and epidemiological features of 36 children with coronavirus disease 2019 (COVID-19) in Zhejiang, China: an observational cohort study. H Qiu, Lancet Infect. Dis. 20Qiu, H. et al. (2020) Clinical and epidemiological features of 36 children with coronavirus disease 2019 (COVID-19) in Zhejiang, China: an observational cohort study. Lancet Infect. Dis. 20, 689-696
Middle East respiratory syndrome coronavirus disease in children. Z A Memish, Pediatr. Infect. Dis. J. 33Memish, Z.A. et al. (2014) Middle East respiratory syndrome coronavirus disease in children. Pediatr. Infect. Dis. J. 33, 904-906
Clinical presentations and outcome of severe acute respiratory syndrome in children. K L Hon, Lancet. 361Hon, K.L. et al. (2003) Clinical presentations and outcome of severe acute respiratory syndrome in children. Lancet 361, 1701-1703
Nasal gene expression of angiotensin-converting enzyme 2 in children and adults. S Bunyavanich, JAMA. 323Bunyavanich, S. et al. (2020) Nasal gene expression of angiotensin-converting enzyme 2 in children and adults. JAMA 323, 2427-2429
An outbreak of severe Kawasaki-like disease at the Italian epicentre of the SARS-CoV-2 epidemic: an observational cohort study. L Verdoni, Lancet. 395Verdoni, L. et al. (2020) An outbreak of severe Kawasaki-like disease at the Italian epicentre of the SARS-CoV-2 epidemic: an observational cohort study. Lancet 395, 1771-1778
Bats are natural reservoirs of SARS-like coronaviruses. W Li, Science. 310Li, W. et al. (2005) Bats are natural reservoirs of SARS-like coronaviruses. Science 310, 676-679
Middle East respiratory syndrome coronavirus in bats, Saudi Arabia. Z A Memish, Emerg. Infect. Dis. 19Memish, Z.A. et al. (2013) Middle East respiratory syndrome coronavirus in bats, Saudi Arabia. Emerg. Infect. Dis. 19, 1819-1823
Genomic characterisation and epidemiology of 2019 novel coronavirus: implications for virus origins and receptor binding. R Lu, Lancet. 395Lu, R. et al. (2020) Genomic characterisation and epidemiology of 2019 novel coronavirus: implications for virus origins and re- ceptor binding. Lancet 395, 565-574
Dampened NLRP3-mediated inflammation in bats and implications for a special viral reservoir host. M Ahn, Nat. Microbiol. 4Ahn, M. et al. (2019) Dampened NLRP3-mediated inflamma- tion in bats and implications for a special viral reservoir host. Nat. Microbiol. 4, 789-799
Dampened STING-dependent interferon activation in bats. J Xie, Cell Host Microbe. 23Xie, J. et al. (2018) Dampened STING-dependent interferon ac- tivation in bats. Cell Host Microbe 23, 297-301
Do men have a higher case fatality rate of severe acute respiratory syndrome than women do?. J Karlberg, Am. J. Epidemiol. 159Karlberg, J. et al. (2004) Do men have a higher case fatality rate of severe acute respiratory syndrome than women do? Am. J. Epidemiol. 159, 229-231
SARS in Singapore-predictors of disease severity. H N Leong, Ann. Acad. Med. Singap. 35Leong, H.N. et al. (2006) SARS in Singapore-predictors of disease severity. Ann. Acad. Med. Singap. 35, 326-331
The pattern of Middle East respiratory syndrome coronavirus in Saudi Arabia: a descriptive epidemiological analysis of data from the Saudi Ministry of Health. I G Alghamdi, Int. J. Gen. Med. 7Alghamdi, I.G. et al. (2014) The pattern of Middle East respira- tory syndrome coronavirus in Saudi Arabia: a descriptive epide- miological analysis of data from the Saudi Ministry of Health. Int. J. Gen. Med. 7, 417-423
Sex differences in immune responses that underlie COVID-19 disease outcomes. T Takahashi, 10.1038/s41586-020-2700-3Nature. Published onlineTakahashi, T. et al. (2020) Sex differences in immune re- sponses that underlie COVID-19 disease outcomes. Nature. Published online August 26, 2020. https://doi.org/10.1038/ s41586-020-2700-3
Sex-based differences in susceptibility to severe acute respiratory syndrome coronavirus infection. R Channappanavar, J. Immunol. 198Channappanavar, R. et al. (2017) Sex-based differences in sus- ceptibility to severe acute respiratory syndrome coronavirus in- fection. J. Immunol. 198, 4046-4053
Breakthrough: chloroquine phosphate has shown apparent efficacy in treatment of COVID-19 associated pneumonia in clinical studies. J Gao, Biosci. Trends. 14Gao, J. et al. (2020) Breakthrough: chloroquine phosphate has shown apparent efficacy in treatment of COVID-19 associated pneumonia in clinical studies. Biosci. Trends 14, 72-73
A trial of lopinavir-ritonavir in adults hospitalized with severe Covid-19. B Cao, N. Engl. J. Med. 382Cao, B. et al. (2020) A trial of lopinavir-ritonavir in adults hospi- talized with severe Covid-19. N. Engl. J. Med. 382, 1787-1799
Effective treatment of severe COVID-19 patients with tocilizumab. X Xu, Proc. Natl. Acad. Sci. U. S. A. 117Xu, X. et al. (2020) Effective treatment of severe COVID-19 pa- tients with tocilizumab. Proc. Natl. Acad. Sci. U. S. A. 117, 10970-10975
Compassionate use of remdesivir for patients with severe Covid-19. J Grein, N. Engl. J. Med. 382Grein, J. et al. (2020) Compassionate use of remdesivir for pa- tients with severe Covid-19. N. Engl. J. Med. 382, 2327-2336
Anakinra for severe forms of COVID-19: a cohort study. T Huet, Lancet Rheumatol. 2Huet, T. et al. (2020) Anakinra for severe forms of COVID-19: a cohort study. Lancet Rheumatol. 2, e393-e400
Colchicine: a potential therapeutic tool against COVID-19. Experience of 5 patients. G Montealegre-Gómez, 10.1016/j.reuma.2020.05.001Reumatol. Clin. Published onlineMontealegre-Gómez, G. et al. (2020) Colchicine: a potential therapeutic tool against COVID-19. Experience of 5 patients. Reumatol. Clin. Published online May 16, 2020. https://doi.org/ 10.1016/j.reuma.2020.05.001
Tocilizumab for the treatment of severe COVID-19 pneumonia with hyperinflammatory syndrome and acute respiratory failure: a single center study of 100 patients in. P Toniati, Autoimmun. Rev. 19102568Toniati, P. et al. (2020) Tocilizumab for the treatment of severe COVID-19 pneumonia with hyperinflammatory syndrome and acute respiratory failure: a single center study of 100 patients in Brescia, Italy. Autoimmun. Rev. 19, 102568
IL6 inhibition in critically ill COVID-19 patients is associated with increased secondary infections. medRxiv. L M Kimmig, 10.1101/2020.05.15.2010353112Published online SeptemberKimmig, L.M. et al. (2020) IL6 inhibition in critically ill COVID-19 patients is associated with increased secondary infections. medRxiv. Published online September 12, 2020. https://doi.org/ 10.1101/2020.05.15.20103531
Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. F Zhou, Lancet. 395Zhou, F. et al. (2020) Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet 395, 1054-1062
TH17 responses in cytokine storm of COVID-19: an emerging target of JAK2 inhibitor Fedratinib. D Wu, X O Yang, J. Microbiol. Immunol. Infect. 53Wu, D. and Yang, X.O. (2020) TH17 responses in cytokine storm of COVID-19: an emerging target of JAK2 inhibitor Fedratinib. J. Microbiol. Immunol. Infect. 53, 368-370
Dysregulation of immune response in patients with coronavirus 2019 (COVID-19) in Wuhan, China. C Qin, Clin. Infect. Dis. 71Qin, C. et al. (2020) Dysregulation of immune response in pa- tients with coronavirus 2019 (COVID-19) in Wuhan, China. Clin. Infect. Dis. 71, 762-768
Cardiovascular implications of fatal outcomes of patients with coronavirus disease. T Guo, COVID-19Guo, T. et al. (2020) Cardiovascular implications of fatal out- comes of patients with coronavirus disease 2019 (COVID-19).
. JAMA Cardiol. 5JAMA Cardiol. 5, 811-818
Risk factors associated with acute respiratory distress syndrome and death in patients with coronavirus disease 2019 pneumonia in Wuhan, China. C Wu, JAMA Intern. Med. 180Wu, C. et al. (2020) Risk factors associated with acute respiratory dis- tress syndrome and death in patients with coronavirus disease 2019 pneumonia in Wuhan, China. JAMA Intern. Med. 180, 934-943
Lymphopenia is associated with severe coronavirus disease 2019 (COVID-19) infections: a systemic review and meta-analysis. Q Zhao, Int. J. Infect. Dis. 96Zhao, Q. et al. (2020) Lymphopenia is associated with severe coronavirus disease 2019 (COVID-19) infections: a systemic re- view and meta-analysis. Int. J. Infect. Dis. 96, 131-135
Thrombocytopenia is associated with severe coronavirus disease 2019 (COVID-19) infections: a metaanalysis. G Lippi, Clin. Chim. Acta. 506Lippi, G. et al. (2020) Thrombocytopenia is associated with se- vere coronavirus disease 2019 (COVID-19) infections: a meta- analysis. Clin. Chim. Acta 506, 145-148
Thrombocytopenia and its association with mortality in patients with COVID-19. X Yang, J. Thromb. Haemost. 18Yang, X. et al. (2020) Thrombocytopenia and its association with mortality in patients with COVID-19. J. Thromb. Haemost. 18, 1469-1472
COVID-19-associated vasculitis and vasculopathy. R C Becker, J. Thromb. Thrombolysis. 50Becker, R.C. (2020) COVID-19-associated vasculitis and vas- culopathy. J. Thromb. Thrombolysis 50, 499-511
Pathological findings of COVID-19 associated with acute respiratory distress syndrome. Z Xu, Lancet Respir. Med. 8Xu, Z. et al. (2020) Pathological findings of COVID-19 associ- ated with acute respiratory distress syndrome. Lancet Respir. Med. 8, 420-422
Kidney disease is associated with in-hospital death of patients with COVID-19. Y Cheng, Kidney Int. 97Cheng, Y. et al. (2020) Kidney disease is associated with in-hospital death of patients with COVID-19. Kidney Int. 97, 829-838
Renal histopathological analysis of 26 postmortem findings of patients with COVID-19 in China. H Su, Kidney Int. 98Su, H. et al. (2020) Renal histopathological analysis of 26 post- mortem findings of patients with COVID-19 in China. Kidney Int. 98, 219-227
Characteristics of ischaemic stroke associated with COVID-19. R Beyrouti, J. Neurol. Neurosurg. Psychiatry. 91Beyrouti, R. et al. (2020) Characteristics of ischaemic stroke as- sociated with COVID-19. J. Neurol. Neurosurg. Psychiatry 91, 889-891
COVID-19 and the cardiovascular system. Y Y Zheng, Nat. Rev. Cardiol. 17Zheng, Y.Y. et al. (2020) COVID-19 and the cardiovascular sys- tem. Nat. Rev. Cardiol. 17, 259-260
Liver injury in COVID-19: management and challenges. C Zhang, Lancet Gastroenterol. Hepatol. 5Zhang, C. et al. (2020) Liver injury in COVID-19: management and challenges. Lancet Gastroenterol. Hepatol. 5, 428-430
2020) C-reactive protein levels in the early stage of COVID-19. L Wang, Med. Mal. Infect. 50Wang, L. (2020) C-reactive protein levels in the early stage of COVID-19. Med. Mal. Infect. 50, 332-334
SARS-CoV-2 gastrointestinal infection causing hemorrhagic colitis: implications for detection and transmission of COVID-19 disease. A Carvalho, Am. J. Gastroenterol. 115Carvalho, A. et al. (2020) SARS-CoV-2 gastrointestinal infection causing hemorrhagic colitis: implications for detection and transmission of COVID-19 disease. Am. J. Gastroenterol. 115, 942-946
Diarrhea during COVID-19 infection: pathogenesis, epidemiology, prevention, and management. F D'amico, Clin. Gastroenterol. Hepatol. 18D'Amico, F. et al. (2020) Diarrhea during COVID-19 infection: pathogenesis, epidemiology, prevention, and management. Clin. Gastroenterol. Hepatol. 18, 1663-1672
Role of the mitochondrial signaling pathway in murine coronavirus-induced oligodendrocyte apoptosis. Y Liu, J. Virol. 80Liu, Y. et al. (2006) Role of the mitochondrial signaling pathway in murine coronavirus-induced oligodendrocyte apoptosis. J. Virol. 80, 395-403
| [
-0.1821015328168869,
-0.1674533486366272,
-0.18693026900291443,
0.06081977114081383,
0.13236981630325317,
0.10429216176271439,
-0.0611860565841198,
0.1896985024213791,
0.16309094429016113,
0.06768271327018738,
-0.08618293702602386,
-0.10140152275562286,
0.034531064331531525,
0.199745029211... |
The Heterogeneous Severity of COVID-19 in African Countries: A Modeling Approach
Salihu Sabiu Musa
Xueying Wang
· Shi Zhao
Shudong Li
Nafiu Hussaini
Weiming Wang
· Daihai He
The Heterogeneous Severity of COVID-19 in African Countries: A Modeling Approach
10.1007/s11538-022-00992-xReceived: 27 May 2021 / Accepted: 1 January 2022 / Published online: 24 January 2022Bulletin of Mathematical Biology (2022) 84:32 S P E C I A L I S S U E : M A T H E M A T I C S A N D C O V I D -1 9SARS-CoV-2 · Pandemic · Reproduction number · Attack rate · Seroprevalence
The COVID-19 pandemic has had a considerable impact on global health and economics. The impact in African countries has not been investigated thoroughly via fitting epidemic models to the reported COVID-19 deaths. We downloaded the data for the 12 most-affected countries with the highest cumulative COVID-19 deaths to estimate the time-varying basic reproductive number (R 0 (t)) and infection attack rate. We develop a simple epidemic model and fitted it to reported COVID-19 deaths in 12 African countries using iterated filtering and allowing a flexible transmission rate. We observe high heterogeneity in the case-fatality rate across the countries, which may be due to different reporting or testing efforts. South Africa, Tunisia, and Libya were most affected, exhibiting a relatively higher R 0 (t) and infection attack rate. Thus, to effectively control the spread of COVID-19 epidemics in Africa, there is a need to consider other mitigation strategies (such as improvements in socioeconomic well-being, healthcare systems, the water supply, and awareness campaigns).Keywords SARS-CoV-2 · Pandemic · Reproduction number · Attack rate · Seroprevalence useful comments and suggestions, which were used to improve the paper from its initial version.Author contributions SSM and DH contributed to conceptualization; SSM, SZ, XW, NH, WW, and DH contributed to formal analysis and writing-original draft; SL and DH contributed to writing-review and editing.
Introduction
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus that has caused the current coronavirus disease pandemic , has strongly affected all regions, including Africa. On February 14, 2020, the disease hit Africa when the first case was reported in Cairo, Egypt (Gilbert et al. 2020;Musa et al. 2020b;World Health Organization 2021a, b). Since then, the disease has spread across Africa, epi-centered in South Africa, and after a year (i.e., by March 25, 2021), over B Daihai He daihai.he@polyu.edu.hk Extended author information available on the last page of the article 7 million people have been infected, including 155,675 thousand related deaths in African region by December 27, 2021(World Health Organization 2021aWorld Health Organization 2021c). The disease, caused by SARS-CoV-2, emerged in China at the end of 2019 and has affected more than 282.8 million individuals and killed over 5.4 million people globally by December 27, 2021(World Health Organization 2021a). COVID-19 shows a faster spreading ability than other coronaviruses of the same family (i.e., SARS-CoV and MERS-CoV) (Chowell et al. 2004;Gilbert et al. 2020;Hu et al. 2020;Li et al. 2020;Lin et al. 2018); it has also destroyed overstretched healthcare systems and weakened the socioeconomic sector worldwide.
In the early phase of the epidemic, the 12 most-affected African countries with COVID-19 deaths were classified into three clusters/groups based on their similarity in exposure risk that originated from three Chinese provinces, namely Guangdong, Fujian, and Beijing, which represented three different levels of risks of importation (high, medium, and relatively low) (Gilbert et al. 2020;Musa et al. 2021a). Each group corresponded to different Chinese airports in the associated province as the main sources of entry risk. Egypt, Algeria, and South Africa were identified as the highest importation risk groups with moderate to high magnitudes of high epidemic response, followed by Nigeria, Ethiopia, Sudan, Morocco, and Kenya, which were classified as moderate importation risk groups with variable magnitudes of response to epidemics with high vulnerability. The last group includes Tunisia, Cameroon, and Zambia, classified as having relatively low importation risk with variable magnitude to respond to epidemics with high vulnerability (Gilbert et al. 2020;World Health Organization 2021b).
With vaccines being developed recently, many are still in clinical trials, and some are already commercially used against COVID-19 infection (World Health Organization 2020). Nonpharmaceutical interventions (NPIs) (which include social distancing, facemasks, total or partial lockdown, contact tracing, quarantine, and isolation) are currently the main strategies to mitigate/prevent the spread of COVID-19 and have helped significantly reduce the mortality rate across the globe (Ferguson et al. 2020;Iboi et al. 2020;World Health Organization 2021a).
The epidemic situation in most African countries has been similar since the beginning of the pandemic in the region. Some of the reasons for this include the following. Most of the NPIs measures are challenging to comply with within most African countries, likely due to socioeconomic behavioral response issues, even during the lockdown period. Also, there is a lack of governmental financial support, as is being provided for local communities and businesses in developed countries. Most African people find it challenging to comply with NPIs measures. For example, ignoring lockdown and quarantine policies, engaging in communal activities to earn incomes for their families, and even helping other most vulnerable populations such as migrants, stateless people, and forcibly displaced refugees. In addition, most African countries cannot afford to get a reasonable quantity of vaccines for their people due to the devastating economic situation caused by the COVID-19 pandemic (Gilbert et al. 2020;Mehtar et al. 2020;Musa et al. 2020bMusa et al. , 2021bVan Zandvoort et al. 2020).
Epidemiological modeling studies have long been used to understand and shed light on the transmission and spread of infectious diseases, including COVID-19 (Chen et al. 2020;Gilbert et al. 2020;He et al. 2021;Li et al. 2020;Musa et al. 2020b).
Further, several works (Gu et al. 2020;Musa et al. 2021b;Roser et al. 2020) suggested a reasonable proportion of un-reported/under-ascertainment in the number of COVID-19 cases and deaths in African counties, which has largely contributed to the fast-spreading of the disease. This was likely due to the low testing rate, especially during the early epidemic following a high positivity rate when the testing rate significantly improved. Some reports investigated the seroprevalence of SARS-CoV-2 among blood donors' in African countries to explore the actual impact of the pandemic in the region. In particular, Uyoga et al. (2021) examined the seroprevalence of anti-SARS-CoV-2 immunoglobulin G antibodies among Kenyan blood donors to determine the extent to which COVID-19 spread in the community. They found that the crude seroprevalence (i.e., amount of SARS-CoV-2 pathogen in blood serum) was estimated at 5.6%, indicating that SARS-CoV-2 exposure is more extensive than case-based surveillance. Another work (in the preprint by the submission date of this manuscript) by Sykes et al. (2021) studied the seroprevalence of SARS-CoV-2 among blood donors in South Africa. The results showed that SARS-CoV-2 prevalence differs by race group and province, with seroprevalence among black donors higher than white donors and other main population subgroups. Their estimation of the seroprevalence (which crudely equals the infection attack rate if we ignore seroreversion) in each of the four cities of the study area was 62.5 in Eastern Cape (95% CI 58.9-66.1); 31.8 in Northern Cape (95% CI 25.3-38.3); 45.5 in Free State (95% CI 39.9-51.1); and 52.1 in KwaZulu Natal (95% CI 49.1-55.2). These results differed from the work of Uyoga et al. (2021), in which the given estimates of the seroprevalence in Kenya (provided by age group) ranged from 3.4 to 10.0 (95% CI 1.6-19.5). Thus, there is a need for more epidemiological studies to describe the pandemic of COVID-19 in African countries (Ndaye et al. 2021).
In this paper, we propose a simple epidemic model to study the transmission dynamics of SARS-CoV-2 in Africa. We also discuss some of the epidemiological characteristics and NPIs implementation and implications in Africa. In particular, we estimate the R 0 (t) and IAR of COVID-19 for the 12 most-affected African countries that experienced high COVID-19-related deaths. The findings of this study are expected to provide valuable insights and suggest effective COVID-19 control measures in Africa. NPIs measures play a crucial role in preventing and controlling SARS-CoV-2 transmission worldwide. However, African countries have some difficulties, especially regarding compliance with NPIs measures. Thus, we report/highlight some essential factors that should be emphasized/improved to control the disease effectively. Simulations results of the proposed model reveal R 0 (t) and IAR's estimated values for the top 12 countries with COVID-19-related deaths in Africa. These parameters are essential epidemiological parameters to curtail the spread of COVID-19 in Africa and beyond.
Materials and Methods
COVID-19 Epidemic Data
A set of COVID-19 observations indexed and arranged in time (Fanoodi et al. 2019) for cases and deaths were extracted from the public domain of the World Health Organization (WHO) dashboard for disease surveillance reports of the 12 African countries with the most COVID-19 deaths. Those are Zambia, Cameroon, Nigeria, Libya, Sudan, Kenya, Ethiopia, Algeria, Tunisia, Morocco, Egypt, and South Africa (World Health Organization 2021a). The time series distribution for the daily confirmations of COVID-19 cases and deaths for the 12 countries with the highest number of deaths in Africa by February 12, 2021, are visualized in Fig. 1, showing the trends of the epidemics. The COVID-19 cases and fatalities are represented by black and red dotted curves, respectively. Based on the data scenarios, we observed that Libya exhibited the first wave of the epidemic. Other counties have shown at least two waves of the COVID-19 epidemic patterns, with South Africa hit worst for both the cases and deaths. The country's population data were obtained from the Worldometer, available via https://www.worldometers.info/population/ (Worldometer 2020). We used COVID-19 deaths data primarily since the COVID-19 cases can be easily influenced by reporting policies and efforts. However, COVID-19 deaths are underreported. To better understand underreporting, we obtained information on excess deaths for South Africa from an online source (The Wall Street Journal 2021). For details of the IFR, see Supplementary Sect. 4.
The SEIHRD Epidemic Model
A susceptible-exposed-infectious-hospitalized-removed-dead (SEIHRD) model was proposed based on the classic SEIR-type (He et al. 2020;Musa et al. 2020a;Zhao et al. 2018) to obtain the fitting results with biologically reasonable parameter values. The model was fitted to the deaths data to visualize the COVID-19 scenario in the 12 most-affected countries with COVID-19 deaths in Africa to shed light on suitable NPIs measures that could appropriately and timely help curtail the outbreaks with very reduced socioeconomic consequences. In the classic SEIR-type model, the population is subdivided into four different compartments according to infection status, representing susceptible (S), exposed (E), infectious (I), and recovered (R). Based on the general epidemiological features of SARS-CoV-2 (Chen et al. 2020;Li et al. 2020), we considered two additional compartments for infected individuals, which are 'hospitalized infected' and 'dead' compartments, represented by H and D, respectively. Susceptible individuals can become exposed after coming into contact with infected people. Exposed individuals can progress to the infectious compartment after the latency period. Infectious individuals can move to the hospitalized compartment, which comes from either mild or severe cases. Infectious individuals can recover/be removed following effective treatment (or naturally) or die from the infection and enter the D compartment. The proposed model (Fig. 2), represented by the following nonlinear ordinary differential equations, is presented below.
S = − β S I N , E = β S I N − σ E, I = σ E − γ I , H = ργ I − ξ H , D = ρξ H ,R = (1 − ρ)γ I + (1 − ρ)ξ H .
Here, parameter β represents the flexible time-varying transmission rate, while parameter σ denotes the disease progression rate from the latent stage to infection status. Parameter γ measures the rate at which individuals move from I to H or R, while parameter ξ denotes the SARS-CoV-2-induced death rate from the H compartment. We have lumped asymptomatically infected and symptomatically infected compartments since we are interested in exploring the overall transmission behavior in African counties, which shows similar epidemic patterns, especially during the early phase of the outbreaks. Although the current model's structure is relatively simpler than many previous studies, it has a flexible transmission rate. Thus, it is not surprising that our model captures the dynamics well in these countries.
In this model, the parameter ρ represents both the proportion of hospitalization among infections and the share of deaths among hospitalizations. Note that hospitalization can be interpreted as symptomatic cases. Thus, the infection fatality ratio (IFR) is given by ρ 2 . We fitted the weekly integrated D to the reported mortality data for each of the 12 countries with the highest number of COVID-19-related deaths in Africa. Note that H could also be interpreted as reported cases. Since we only fit D to reported deaths rather than H to reported cases (or hospitalization), the exact definition of H is not crucial. We could define the proportions separately (the numbers of hospitalizations among infections, and the share of deaths among hospitalizations), but that would introduce one more parameter that would require more information or assumption with virtually the same fitting performance. Classic theory tells us that the dynamics of the model mainly depend on β and γ and less sensitive to other parameters.
The other assumptions include negative binominal measurement noise in reporting with an overdispersion parameter φ and a time-varying transmission rate (β), which is an exponential cubic spline function with 7 nodes. The effective basic reproduction number R 0 (t) is given byR 0 (t) ≈ β(t)/γ . For more details regarding the model fitting process, see (He et al. 2020;Musa et al. 2020a;Zhao et al. 2018). Iterated filtering algorithms are used to fit the model with an additional death class to the reported COVID-19 deaths for the 12 countries with the most deaths in Africa to quantify epidemic scenarios in Africa using the estimate of reproduction number. Thus, the proposed model was fitted to the SARS-CoV-2 mortality data for each of the 12 African countries. We estimated the IFR (with some restriction, see supplementary Sect. 4) and the time-varying transmission rate of COVID-19 in African countries.
Results
In Figs. 3 and 4, we used the proposed SEIHRD model (depicted in Fig. 2) to simulate the COVID-19 mortality datasets (weekly) for the 12 African countries with the most COVID-19 deaths to explore the dynamic characteristics of SARS-CoV-2 in Africa. We estimated the time-varying basic reproductive number, R 0 (t), and the infection attack rate, IAR, for each of the 12 countries, as depicted in Figs. 3 and Algeria 0.042 African countries with the most COVID-19 deaths, which were hit milder (with low reporting rates). Deaths are population standardized (i.e., deaths per 1 million people). The median of the simulation is represented by the black curve, and the time-varying basic reproductive number (R 0 (t)) is denoted by the blue dashed curve. The 95% confidence interval of the simulation is shown by the shaded (gray) region. The estimated IAR is displayed in the title of each panel 4, respectively. Figure 3 shows the fitting results of nine of the 12 countries with the most COVID-19 deaths (Algeria, Cameroon, Egypt, Ethiopia, Kenya, Morocco, Libya, Nigeria, Sudan, Tunisia, and Zambia), which were hit milder or had a relatively lower reporting rate. Figure 4 displays the fitting results of three of the 12 countries with the most COVID-19 deaths (Libya, South Africa, and Tunisia), which hit harder or had a relatively higher reporting rate. The weekly confirmed deaths are represented by the red circle, with the black curve representing the medium simulation, and the gray shaded region denoting the 95% confidence interval (CI) based on 1000 simulations. By February 2021, Cameroon, Sudan, Algeria, and Tunisia were witnessing the third wave of the COVID-19 epidemic, whereas Zambia, Nigeria, Libya, Kenya, Ethiopia, Morocco, Egypt, and South Africa were observing the second wave of the SARS-CoV-2 epidemic. The increase in transmission rate in these countries was likely due to the partial or non-compliance of the NPIs measures, age factor (the share of the elderly population), seasonality, or behavioral changes (see, for instance, (Moges et al. 2014)). For South Africa, we fitted our model to excess deaths, as seen in Fig. 4d. With the assumption IFR ≥ 0. 68%, we yielded a similar estimated IAR per using the reported COVID-19. The excess death rate is approximately 3.4-fold of the reported COVID-19 rate.
• •• • • • • • • •• ••• •• • •• ••••• • ••• ••• ••• • • • •• •• • • •••• ••••Mar3.0 R 0 (t) Cameroon 0.022 •• • • • • • • • • • • • • • • • • • • • • • • • • •• • •••• • •••• • • •• •• •• • • • •• Mar3.0 R 0 (t) Egypt 0.064 • • • • • • •• • • • • • • • •• •• • • • • • •• •••• ••••• ••• • • • • ••••• ••••Mar•••• •• •• •• • • • •••• • • • • •• •• •• •• ••• •• ••• • •••• •••• • •• ••Mar3.0 R 0 (t) Kenya 0.062 •• •• •••• •• •• • • • • •• •• • • •• • • ••• • • • • • • •• • •• • • • • • ••• • • •Mar3.0 R 0 (t) Morocco 0.15 •• • • • • • •• •••• ••• •• • • • • • • ••• • • • • • • • • ••• •• •• •• • • • • •• •Mar•• •• •• •• •••• •• •• •••• ••• ••••• •• •• •••• •• ••• • •• •••••••MarR 0 (t) Sudan 0.046 • • • • • • • • • • • • • •• • • • • • • • •• • • • • ••••• • • • • • •• • •• • • • • • •••Mar
Libya 0.155 In Table 1, we obtained estimated values of the SARS-CoV-2 infection attack rate (IAR, the ratio of mortality per case in a particular population) for the 12 countries with the most deaths in Africa by February 2021. South Africa was hit hardest with an IAR of 0.414, followed by Tunisia with an IAR of 0.213 and then Libya with an IAR of 0.155, while Cameroon and Algeria were hit the mildest, with IARs of 0.022 and 0.042, respectively. These results indicate the impacts of NPIs, and thus highlight the imperative need to implement other control strategies to mitigate epidemics in Africa and beyond. We presume that the reported COVID-19 deaths are relatively reliable.
••• • •• •• ••• • •• • •• • • • • • • • • • • • • • • • • • •••• • ••• •• • • • •• • •
Mar
••• •• ••• •• • • • •• •• •• • ••• • ••• •• •• • • • • • •• • • • • • • • •• • • • •
Mar
In Supplementary Table S1, we report the COVID-19 index case(s) scenarios for the 12 countries with the most deaths in Africa. SARS-CoV-2 was first reported in Egypt on February 14, 2020, followed by exponentially growing cases that spread in all parts of Africa, with South Africa as the epicenter until now. Consequently, the estimated seroprevalences of SARS-COV-2 (i.e., the estimated proportion of individuals in a population with positive test for COVID-19) are reported in Supplementary Table S2, which indicates that South Africa has an estimated seroprevalence of approximately 50% from blood donors (Shaw et al. 2021;Sykes et al. 2021). This result highlights that South Africa has been hit harder, which may be a consequence of the high proportion
Discussion and Conclusions
It has been more than a year since COVID-19 emerged in China and spread rapidly to over 200 countries and territories. African countries have slightly strengthened their preparedness plans against unexpected disease outbreaks such as the COVID-19 pandemic based on the lessons learned. Those include timely responses; airport surveillance and temperature screening at ports of entry; improvement in diagnostic centers for testing/mass testing; strengthened collaboration with other countries in other regions like China, the US, and the UK (for instance, the deployment of medical personnel from the UK, donations of testing kits and PPEs by the Jack Ma Foundation, etc.) (Gilbert et al. 2020;World Health Organization 2021b). Africa was fortunate to report its first case of COVID-19 at least a month after many countries on other continents had already reported thousands of cases and deaths (Li et al. 2020;World Health Organization 2021a;Zhao et al. 2020); making the continent advantageous over others for timely preparations and responses to the pandemic in a variety of ways based on the lessons learned.
To visualize the actual scenario of the SARS-CoV-2 in 12 African countries with the most deaths, we simulated the model using weekly mortality data for each of the 12 countries to guide policymaking for effectively controlling the COVID-19 pandemic in Africa. To achieve reasonable fittings and estimates, we made some assumptions; in particular, we divided these countries into two groups. Group 1) consists of South Africa, Libya, Tunisia, with a value of ρ above 0.045 (i.e., IFR > 0.2%). These countries reported more deaths per capita, which suggests a severe impact and/or efficient reporting of deaths, and their IARs were 41.4%, 15.5%, and 21.3%, respectively. Group 2) consists of nine other countries (with a value of ρ between 0.01 and 0.04, i.e., 0.01% < IFR < 0.16%), which shows mild impact and/or underreporting of deaths. Their IARs varies between 2.2 and 20.2%, with a median of 6.2%. In Fig. 3, we depicted the time series fitting results of weekly reported COVID-19 deaths in 9 of the 12 countries (Algeria, Cameroon, Ethiopia, Kenya, Morocco, Nigeria, Sudan, and Zambia) that were hit milder or had a low reporting rate, and Fig. 4 reveals the time series fitting results of weekly reported COVID-19 deaths in 3 of the 12 countries (Libya, South Africa, and Tunisia) that were hit harder or had a relatively higher reporting rate.
The excess death has been one of the main quantities representing a more reliable metric for comparing and understanding the impacts of the pandemic among countries. Excess death is used to estimate the additional number of mortalities before and during the pandemic period more frequently than the presumed number of fatalities. It has become one of the crucial factors in identifying the relative effectiveness of prevention and control measures between countries. Although inconsistencies in reporting and testing between countries could affect the estimation of epidemiological parameters, excess mortality could help overcome this inherent inequality; however, its role in helping us understand why mortality varies among countries is still inadequate. Thus, we used excess deaths as a proxy for deaths due to COVID-19 to have a clear picture of the current situation in African counties, even though it may not represent the actual scenario (Beaney et al. 2020;Roser et al. 2020). Furthermore, according to Li et al. (2021), excess deaths = true COVID-19 deaths-avoided death due to lockdown effect + added deaths due to lockdown effect. Thus, it is clear that excess deaths will be a good proxy only when the last two terms on the right hand of the equation cancel each other. Suppose the second term is larger than the third term. Excess deaths could still be an underestimate of the actual COVID-19 deaths. Nevertheless, it addressed the underreporting in the reported COVID-19 deaths to some extent. All the above assumes that all causes of deaths should be at the average level of the previous five years, i.e., without a large-scale, long-term trend. See Supplementary Figures S2 and S3 for the comparison of excess deaths and COVID-19 reported death and a loglikelihood profile for IFR for South Africa, respectively.
Due to the asymptomatic feature of COVID-19, which could be up to 84% (Gu et al. 2020), and non-compliance of NPIs by the general public (which includes noncompliance for community testing surveillance, quarantine/isolation policy, lockdown, facemask use, and social distancing), it is highly likely that COVID-19 cases were underreported or under-ascertained in African countries (Gu et al. 2020;Musa et al. 2021b). Consequently, South Africa, as the epicenter of the pandemic in Africa, has recorded the highest morbidity and mortality cases of CVID-19 cases, which has eventually been one of the significant reasons for the occurrence of underreporting or under-ascertainment issues since the healthcare system was overwhelmed. Besides, the government cannot follow up with all the contacts for effective contact tracing, which results in a sizeable unobserved number of cases and deaths. Recent report (Abdool Karim 2020; National Institute for Communicable Diseases 2020) suggested that only about one in every four mild cases would be ascertained in South Africa.
Africa's COVID-19 responses and control strategies were largely not contextspecific (Iwuoha and Aniche 2020;Uyoga et al. 2021). The responses and mitigation strategies via NPIs employed in Africa were described as replication or simply the COVID-19 copy-and-paste policies that were implemented in countries other than Africa, such as China, United Kingdom, Germany and United States, despite the variability in epidemiological characteristics, differences in weather and climate, and different socioeconomic growth levels, which probably impact the transmission of the disease in Africa. Moreover, the copy-and-paste approach (also known as the 'one-size-fits-all' policy) is hugely adopted and implemented in African countries. Although, some of those (stringent) measures were needless and turned out to be useless, causing more socioeconomic hardship to vulnerable populations. For instance, many African countries impulsively adopted the same lockdown policy without the requisite knowledge of the COVID-19 clinical and epidemiological features in the region, which could have serious negative consequences to the communities (World Health Organization 2021b).
Furthermore, social distancing policies and restrictions on social gatherings (such as banning weddings, religious activities, and funeral ceremonies) have been imposed to curtail the spread of the virus, even though it is almost practically impossible for many African countries to comply. Mandatory wearing of facemasks in public places and the use of hand sanitizers were also pervasive COVID-19 control measures in Africa, even though compliance is very difficult and problematic due to ignorance, poverty, resource constraints, and a lack of awareness (Iwuoha and Aniche 2020; World Health Organization 2021b). Although some successes have been achieved concerning these response strategies, critics have described them as one-size-fits-all or copy-and-paste approaches because of inappropriateness and unfavorability to local settings in Africa (Dzisi and Dei 2020;Nyarko et al. 2020;Roser et al. 2020). In addition, one more important control measure is school closure, which has been massively criticized in Africa since many countries on the continent spontaneously closed down schools with the absence of exhaustive e-learning systems and inadequate infrastructure, as has been practiced in many counties of continents other than Africa (Iwuoha and Aniche 2020).
Some of the main challenges regarding the fight against the COVID-19 pandemic in Africa include the imposition of the hand-hygiene policy when the majority of Africans do not have access to an adequate and potable water supply, temperature screening at airports for travelers without considering asymptomatic carriers (asymptomatically infected people), the impossibility of work from home policies, and an insufficient quantity of PPEs, especially for frontline health workers, insufficient data sharing, and illegal crossing of borders at non-official points of entry (Arakpogun et al. 2020;Ataguba 2020;Irlacher and Koch 2021;World Health Organization 2021b). During lockdowns, food prices have skyrocketed significantly in many countries on the continent due to panic buying and interruptions in the food supply chain within the community and between countries (Vos et al. 2020). Although lockdowns have helped control the spread of the disease, they plunged millions of people into extreme poverty (Iwuoha and Aniche 2020;Nyarko et al. 2020;World Health Organization 2021b). And likely has greater consequences and can kill more people than COVID-19 due to its negative impacts that have exhausted countless individuals (Iwuoha and Aniche 2020). Aside from the extreme poverty caused (likely) due to the effects of lockdowns, there were issues of human rights abuses by government officials or security agencies that added to the hardships already emanating from the lockdown policy in Africa (Amadasun 2020).
Another unexpected repercussion of NPIs in Africa was the effect of already fragile healthcare systems. Neglecting public health needs in the wake of COVID-19 has been reported with an unprecedented reduction in health service usage, causing more threats concerning other infectious illnesses such as malaria, HIV/AIDS, and meningitis (Abdool Karim 2020; Jewell et al. 2020;Sherrard-Smith et al. 2020). These implications may even cause severe consequences during the post-COVID-19 pandemic because of their socioeconomic destruction. We also observed that most of the top 12 African countries with the most COVID-19 deaths reported their first COVID-19 case(s) between February and March 2020 (see Supplementary Table S1), which indicates that most of the stringency index policies are similar in most countries in Africa. Future work plans to extend the current study by incorporating possible reinfection or vertical transmission in the model to explore its impact on the overall transmission dynamics in African countries (Tang et al. 2021;Musa et al. 2021c).
Overall, Africa has done remarkably well in awareness and enlightenment campaigns by the media and civil society in disseminating health education and communication on COVID-19 prevention and control, which helps in curtailing the spread of SARS-CoV-2 in the African region (World Health Organization 2021b). Even though a more favorable/suitable policy needs to be considered, which can be implemented and easily complied with by the general public to effectively control the spread of COVID-19, with significantly reduced economic hardships and negative consequences, especially during a post-COVID-19 pandemic. With the assumed range of IFR and flexible transmission rate, we model a simple unified model of the reported deaths in 12 African countries. The group choice for countries was justified by the tests per capita performed across countries and the raw case-fatality rate across counties (Supplementary Table S3). For instance, South Africa performed more tests per capita than other countries, which implies a relatively higher reporting effort. The raw case-fatality rate is high in South Africa. Combining these two aspects, we decide to allocate South Africa to the high ρ group. Our fitting result reveals that South Africa, Libya, Tunisia, Ethiopia, and Morocco were hit harder with the SAR-CoV-2 epidemic in Africa. Thus, we suggest an imperative need to improve the socioeconomic situation, quality water supply, and healthcare system (including the provision of adequate health workers, PPEs, and test kits) in Africa to effectively and timely control SARS-CoV-2 outbreaks.
In conclusion, we proposed a simple unified model to report deaths scenarios in 12 African countries and excess deaths in South Africa. We gained a qualitative idea of the severity in African countries. In the next step, we plan to associate the reconstructed R 0 (t) with government control measures and possible voluntary social distancing in each country. In summary, we conducted large-scale data analysis and modeling work for the 12 African countries with the most deaths cases and shed light on the possible IFR and infection attack rate. Due to different economic levels, control measures, and testing and reporting efforts, we found considerable variation across countries. Our estimated infection attack rates, which are based on the assumed range of IFR, are largely in line with population-level serological studies. Our work is essential since it is the first large-scale population-level modeling work for these African countries. Along with population-level serological studies, our work provides insight into the possible severity in these countries.
Supplementary Information
The online version contains supplementary material available at https://doi. org/10.1007/s11538-022-00992-x.
Fig. 1
1Daily confirmed cases (in black triangles) and deaths (in red triangles) of COVID-19 in 12 African countries with the most cases of deaths from COVID-19 (population standardized, cases and deaths per 1 million people)
Fig. 2
2Schematic diagram of COVID-19 model. The compartments in green represent the uninfected populations, the orange compartments represent the infected populations, and the dark orange class denotes the death proportion
Fig. 3
3Time series fitting results of weekly confirmed COVID-19 deaths (in red circles) in nine of the 12
Fig. 4
4Time series fitting results of weekly confirmed COVID-19 deaths (in red circles) in three of the 12 African countries with most COVID-19 deaths, which were hit harder (or with a relatively higher reporting effort): a Libya, b South Africa, c Tunisia and d South Africa with excess deaths. Deaths are population standardized (i.e., deaths per 1 million people). The median of the simulation is represented by the black curve, and the time-varying basic reproductive number (R 0 (t)) is denoted by the blue dashed curve. The 95% confidence interval of the simulation is shown by the shaded (gray) region. The estimated IAR is portrayed in the title of each panel
Table 1
1Results of the infection attack rates (IARs) for the 12 African countries with the most COVID-19 deaths by the end of February 2021 of mild or asymptomatic cases, comprising up to 80% of total infections(Eckerle and Meyer 2020).SupplementaryTable S4presents the results of the model's estimated parameters by employing the log-likelihood estimation technique. South Africa, Egypt, and Tunisia have log-likelihood values of − 301.112, − 263.928, and − 232.474, respectively. These outcomes signal that South Africa has the highest transmission potential compared to other countries. InSupplementary Table S4, we present a summary of the estimated results of the time-varying transmission rate using a fixed number of nodes (n m ), 7. Different values of the time-varying transmission rate were obtained based on the different simulation runs. The state values of the model were assigned, with initial values given inSupplementary Table S4.Country
Population size
Reported deaths
Est. Infection attack rate
Algeria
43,851,044
2973
0.042
Cameroon
26,545,863
523
0.022
Egypt
102,334,404
10,541
0.064
Ethiopia
114,963,588
2321
0.202
Kenya
53,771,296
1847
0.062
Libya
6,871,292
2156
0.155
Morocco
36,910,560
8598
0.15
Nigeria
206,139,589
1891
0.048
South Africa
59,308,690
49,667
0.414
Sudan
43,849,260
1880
0.046
Tunisia
11,818,619
7911
0.213
Zambia
18,383,955
1059
0.092
AcknowledgementsThe authors are thankful to the handling editor and anonymous reviewers for theirAuthors and Affiliations
The South African response to the pandemic. Abdool Karim, S S , New Engl J Med. 38295Abdool Karim SS (2020) The South African response to the pandemic. New Engl J Med 382:e95
COVID-19 palaver: ending rights violations of vulnerable groups in Africa. S Amadasun, World Dev. 134105054Amadasun S (2020) COVID-19 palaver: ending rights violations of vulnerable groups in Africa. World Dev 134:105054
Africa's resilience in the face of COVID-19 pandemic: let's talk about it!. E Arakpogun, Z El Sahn, K S Prime, at SSRN 3640311Arakpogun E, El Sahn Z, Prime KS et al. (2020) Africa's resilience in the face of COVID-19 pandemic: let's talk about it!. Available at SSRN 3640311
COVID-19 pandemic, a war to be won: understanding its economic implications for Africa. J E Ataguba, Appl Health Econ Health Policy. 183Ataguba JE (2020) COVID-19 pandemic, a war to be won: understanding its economic implications for Africa. Appl Health Econ Health Policy 18(3):325-328
Excess mortality: the gold standard in measuring the impact of COVID-19 worldwide?. T Beaney, J M Clarke, V Jain, J R Soc Med. 113Beaney T, Clarke JM, Jain V et al (2020) Excess mortality: the gold standard in measuring the impact of COVID-19 worldwide? J R Soc Med 113:329-334
. S S Musa, S. S. Musa et al.
Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. N Chen, M Zhou, X Dong, Lancet. 395Chen N, Zhou M, Dong X et al (2020) Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet 395:507-513
Model parameters and outbreak control for SARS. G Chowell, C Castillo-Chavez, P W Fenimore, Emerg Infect Dis. 101258Chowell G, Castillo-Chavez C, Fenimore PW et al (2004) Model parameters and outbreak control for SARS. Emerg Infect Dis 10:1258
Adherence to social distancing and wearing of masks within public transportation during the COVID 19 pandemic. Ekj Dzisi, O A Dei, Transp Res Interdiscip Perspect. 7100191Dzisi EKJ, Dei OA (2020) Adherence to social distancing and wearing of masks within public transportation during the COVID 19 pandemic. Transp Res Interdiscip Perspect 7:100191
SARS-CoV-2 seroprevalence in COVID-19 hotspots. I Eckerle, B Meyer, Lancet. 396Eckerle I, Meyer B (2020) SARS-CoV-2 seroprevalence in COVID-19 hotspots. Lancet 396:514-515
Reducing demand uncertainty in the platelet supply chain through artificial neural networks and ARIMA models. B Fanoodi, B Malmir, F F Jahantigh, Comput Biol Med. 113103415Fanoodi B, Malmir B, Jahantigh FF (2019) Reducing demand uncertainty in the platelet supply chain through artificial neural networks and ARIMA models. Comput Biol Med 113:103415
Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand. N Ferguson, D Laydon, Nedjati Gilani, G , 10.25561/77482Imp Coll Lond. 9ReportFerguson N, Laydon D, Nedjati Gilani G et al (2020) Report 9: Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand. Imp Coll Lond. https://doi.org/10.25561/ 77482
Preparedness and vulnerability of African countries against importations of COVID-19: a modelling study. M Gilbert, G Pullano, F Pinotti, Lancet. 395Gilbert M, Pullano G, Pinotti F et al (2020) Preparedness and vulnerability of African countries against importations of COVID-19: a modelling study. Lancet 395:871-877
COVID-19 prediction in South Africa: estimating the unascertained cases-the hidden part of the epidemiological iceberg. X Gu, B Mukherjee, S Das, 10.1101/2020.12.10.20247361Gu X, Mukherjee B, Das S et al (2020) COVID-19 prediction in South Africa: estimating the unascertained cases-the hidden part of the epidemiological iceberg. medRxiv. https://doi.org/10.1101/2020.12.10. 20247361
New estimates of the Zika virus epidemic attack rate in Northeastern Brazil from 2015 to 2016: A modelling analysis based on Guillain-Barré Syndrome (GBS) surveillance data. D He, S Zhao, Q Lin, PLoS Negl Trop Dis. 147502He D, Zhao S, Lin Q et al (2020) New estimates of the Zika virus epidemic attack rate in Northeastern Brazil from 2015 to 2016: A modelling analysis based on Guillain-Barré Syndrome (GBS) surveillance data. PLoS Negl Trop Dis 14:e0007502
The unexpected dynamics of COVID-19 in Manaus, Brazil: herd immunity versus interventions. D He, Y Artzy-Randrup, S S Musa, 10.1101/2021.02.18.21251809He D, Artzy-Randrup Y, Musa SS et al (2021) The unexpected dynamics of COVID-19 in Manaus, Brazil: herd immunity versus interventions. medRxiv. https://doi.org/10.1101/2021.02.18.21251809
Characteristics of SARS-CoV-2 and COVID-19. B Hu, H Guo, P Zhou, Nat Rev Microbiol. 193Hu B, Guo H, Zhou P et al (2020) Characteristics of SARS-CoV-2 and COVID-19. Nat Rev Microbiol 19(3):141-154
Mathematical modeling and analysis of COVID-19 pandemic in Nigeria. E A Iboi, O O Sharomi, C N Ngonghala, Math Biosci Eng. 176Iboi EA, Sharomi OO, Ngonghala CN et al (2020) Mathematical modeling and analysis of COVID-19 pandemic in Nigeria. Math Biosci Eng 17(6):7192-7220
Working from home, wages, and regional inequality in the light of Covid-19. M Irlacher, M Koch, Jahrbücher für Nationalökonomie und Statistik. 2413Irlacher M, Koch M (2021) Working from home, wages, and regional inequality in the light of Covid-19. Jahrbücher für Nationalökonomie und Statistik 241(3):373-404
Covid-19 lockdown and physical distancing policies are elitist: towards an indigenous (Afro-centred) approach to containing the pandemic in sub-urban slums in Nigeria. V C Iwuoha, E T Aniche, Local Environ. 25Iwuoha VC, Aniche ET (2020) Covid-19 lockdown and physical distancing policies are elitist: towards an indigenous (Afro-centred) approach to containing the pandemic in sub-urban slums in Nigeria. Local Environ 25:631-640
Potential effects of disruption to HIV programmes in sub-Saharan Africa caused by COVID-19: results from multiple mathematical models. B L Jewell, E Mudimu, J Stover, Lancet HIV. 7Jewell BL, Mudimu E, Stover J et al (2020) Potential effects of disruption to HIV programmes in sub-Saharan Africa caused by COVID-19: results from multiple mathematical models. Lancet HIV 7:e629-e640
Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. Q Li, X Guan, P Wu, N Engl J Med. 382Li Q, Guan X, Wu P et al (2020) Early transmission dynamics in Wuhan, China, of novel coronavirus-in- fected pneumonia. N Engl J Med 382:1199-1207
Excess pneumonia and influenza death as herald wave of COVID-19 in England and Wales, United Kingdom. C Li, X Zhang, Y Zhu, J Infect. 822Li C, Zhang X, Zhu Y et al (2021) Excess pneumonia and influenza death as herald wave of COVID-19 in England and Wales, United Kingdom. J Infect 82(2):282-327
Modeling the spread of middle east respiratory syndrome coronavirus in Saudi Arabia. Q Lin, A P Chiu, S Zhao, Stat Methods Med Res. 27Lin Q, Chiu AP, Zhao S et al (2018) Modeling the spread of middle east respiratory syndrome coronavirus in Saudi Arabia. Stat Methods Med Res 27:1968-1978
Limiting the spread of COVID-19 in Africa: one size mitigation strategies do not fit all countries. S Mehtar, W Preiser, N A Lakhe, Lancet Glob Health. 8Mehtar S, Preiser W, Lakhe NA et al (2020) Limiting the spread of COVID-19 in Africa: one size mitigation strategies do not fit all countries. Lancet Glob Health 8:e881-e883
Emerging population ageing challenges in Africa: a case of Ethiopia Kokusai Hoken Iryo. A G Moges, N Tamiya, H Yamamoto, J Int Health. 29Moges AG, Tamiya N, Yamamoto H (2014) Emerging population ageing challenges in Africa: a case of Ethiopia Kokusai Hoken Iryo. J Int Health 29:11-15
Mechanistic modelling of the large-scale Lassa fever epidemics in Nigeria from 2016 to 2019. S S Musa, S Zhao, D Gao, J Theor Biol. 493110209Musa SS, Zhao S, Gao D et al (2020a) Mechanistic modelling of the large-scale Lassa fever epidemics in Nigeria from 2016 to 2019. J Theor Biol 493:110209
Estimation of exponential growth rate and basic reproduction number of the coronavirus disease 2019 (COVID-19) in Africa. S S Musa, S Zhao, M H Wang, Infect Dis Poverty. 9Musa SS, Zhao S, Wang MH et al (2020b) Estimation of exponential growth rate and basic reproduction number of the coronavirus disease 2019 (COVID-19) in Africa. Infect Dis Poverty 9:1-6
Mathematical modeling of COVID-19 epidemic with effect of awareness programs. S S Musa, S Qureshi, S Zhao, Infect Dis Model. 6Musa SS, Qureshi S, Zhao S et al (2021a) Mathematical modeling of COVID-19 epidemic with effect of awareness programs. Infect Dis Model 6:448-460
Estimation of COVID-19 under-ascertainment in Kano, Nigeria during the Early Phase of the Epidemics. S S Musa, S Zhao, N Hussaini, Alex Eng J. 60Musa SS, Zhao S, Hussaini N et al (2021b) Estimation of COVID-19 under-ascertainment in Kano, Nigeria during the Early Phase of the Epidemics. Alex Eng J 60:4547-4554
Vertical transmission of SARS-CoV-2: a systematic review of systematic reviews. S S Musa, U M Bello, S Zhao, Viruses. 1391877Musa SS, Bello UM, Zhao S et al (2021c) Vertical transmission of SARS-CoV-2: a systematic review of systematic reviews. Viruses 13(9):1877
National Institute for Communicable Diseases (2020) South African COVID-19 Modelling Consortium (Projections). National Institute for Communicable Diseases (2020) South African COVID-19 Modelling Consor- tium (Projections), https://www.nicd.ac.za/diseases-a-z-index/disease-index-covid-19/surveillance- reports/modelling-consortium-projections/. Accessed from 10 Oct 2021
Challenges in interpreting SARS-CoV-2 serological results in African countries. A N Ndaye, A Hoxha, J Madinga, Lancet Glob Health. 95Ndaye AN, Hoxha A, Madinga J et al (2021) Challenges in interpreting SARS-CoV-2 serological results in African countries. Lancet Glob Health 9(5):e588-e589
The impact on public health and economy using lockdown as a tool against COVID-19 pandemic in Africa: a perspective. R Nyarko, E Boateng, I Kahwa, 10.16966/2471-8211.188J Epidemiol Public Health Rev. Nyarko R, Boateng E, Kahwa I et al (2020) The impact on public health and economy using lockdown as a tool against COVID-19 pandemic in Africa: a perspective. J Epidemiol Public Health Rev. https:// doi.org/10.16966/2471-8211.188
Coronavirus pandemic (COVID-19). Our world in data. M Roser, H Ritchie, E Ortiz-Ospina, Roser M, Ritchie H, Ortiz-Ospina E et al. (2020) Coronavirus pandemic (COVID-19). Our world in data. https://ourworldindata.org/coronavirus?te=1&nl=nicholas-kristof&emc=edit_nk_20200622
Higher SARS-CoV-2 seroprevalence in workers with lower socioeconomic status in Cape Town. J A Shaw, M Meiring, T Cummins, South Africa. PLoS ONE. 16247852Shaw JA, Meiring M, Cummins T et al (2021) Higher SARS-CoV-2 seroprevalence in workers with lower socioeconomic status in Cape Town, South Africa. PLoS ONE 16:e0247852
The potential public health consequences of COVID-19 on malaria in Africa. E Sherrard-Smith, A B Hogan, A Hamlet, Nat Med. 26Sherrard-Smith E, Hogan AB, Hamlet A et al (2020) The potential public health consequences of COVID-19 on malaria in Africa. Nat Med 26:1411-1416
Prevalence of anti-SARS-CoV-2 antibodies among blood donors in Northern Cape. W Sykes, L Mhlanga, R Swanevelder, 10.21203/2Frs.3.rs-233375%2Fv1KwaZulu-Natal, Eastern Cape, and Free State provinces of South AfricaSykes W, Mhlanga L, Swanevelder R et al. (2021) Prevalence of anti-SARS-CoV-2 antibodies among blood donors in Northern Cape, KwaZulu-Natal, Eastern Cape, and Free State provinces of South Africa in January 2021 Research Square https://doi.org/10.21203/2Frs.3.rs-233375%2Fv1
Reinfection or reactivation of severe acute respiratory syndrome coronavirus 2: a systematic review front. X Tang, S S Musa, S Zhao, 10.3389/fpubh.2021.663045Public Health. 9663045Tang X, Musa SS, Zhao S et al (2021) Reinfection or reactivation of severe acute respiratory syndrome coronavirus 2: a systematic review front. Public Health 9:663045. https://doi.org/10.3389/fpubh.2021. 663045
South Africa's Drop in COVID-19 Cases Adds Questions About Waves of Infections. The Wall Street Journal. The Wall Street Journal (2021) Coronavirus. South Africa's Drop in COVID-19 Cases Adds Questions About Waves of Infections. 2021. Retrieved from https://www.wsj.com/articles/south-africas-drop- in-covid-19-cases-adds-to-questions-about-waves-of-infections-11615734003. Accessed from 1 Apr 2021
Seroprevalence of anti-SARS-CoV-2 IgG antibodies in kenyan blood donors. S Uyoga, I M Adetifa, H K Karanja, Science. 371Uyoga S, Adetifa IM, Karanja HK et al (2021) Seroprevalence of anti-SARS-CoV-2 IgG antibodies in kenyan blood donors. Science 371:79-82
Response strategies for COVID-19 epidemics in African settings: a mathematical modelling study. K Van Zandvoort, C I Jarvis, C A Pearson, BMC Med. 18Van Zandvoort K, Jarvis CI, Pearson CA et al (2020) Response strategies for COVID-19 epidemics in African settings: a mathematical modelling study. BMC Med 18:1-19
How much will global poverty increase because of COVID-19 Intl Food Policy Research Institute 1-28. R Vos, W Martin, D Laborde, 6Vos R, Martin W, Laborde D (2020) How much will global poverty increase because of COVID-19 Intl Food Policy Research Institute 1-28, https://www.ifpri.org/blog/how-much-will-global-poverty-increase- because-covid-19. Accessed 6 May 2021
World Health Organization (2020) Coronavirus disease (COVID-19). COVID-19 Vaccines. World Health Organization (2020) Coronavirus disease (COVID-19), COVID-19 Vaccines, https://www. who.int/emergencies/diseases/novel-coronavirus-2019/covid-19-vaccines. Accessed 10 Oct 2021
World Health Organization (2021b) Regional Office for Africa. COVID-19 Strategic Response Plan in the WHO African Region. World Health Organization (2021b) Regional Office for Africa. COVID-19 Strategic Response Plan in the WHO African Region, https://www.afro.who.int/fr/node/12891. Accessed from 4 Mar 2021
World Health Organization (2021a) Coronavirus disease (COVID-19) Dashboard. World Health Organization (2021a) Coronavirus disease (COVID-19) Dashboard, https://covid19.who.int/. Accessed from 10 Oct 2021
World Health Organization (2021c) Coronavirus disease (COVID-19) Weekly Epidemiological Update and Weekly Operational Update. World Health Organization (2021c) Coronavirus disease (COVID-19) Weekly Epidemiological Update and Weekly Operational Update, https://www.who.int/emergencies/diseases/novel-coronavirus-2019/ situation-reports/. Accessed from 29 Mar 2021
COVID-19 Coronavirus Pandemic. Worldometer, Worldometer (2020) COVID-19 Coronavirus Pandemic, https://www.worldometers.info/coronavirus/# countries. Accessed From 7 Apr 2021
Modelling the large-scale yellow fever outbreak in Luanda, Angola, and the impact of vaccination. S Zhao, L Stone, D Gao, PLoS Negl Trop Dis. 126158Zhao S, Stone L, Gao D et al (2018) Modelling the large-scale yellow fever outbreak in Luanda, Angola, and the impact of vaccination. PLoS Negl Trop Dis 12:e0006158
Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: a data-driven analysis in the early phase of the outbreak. S Zhao, Q Lin, J Ran, Int J Infect Dis. 92Zhao S, Lin Q, Ran J et al (2020) Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: a data-driven analysis in the early phase of the outbreak. Int J Infect Dis 92:214-217
Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
| [
0.0201705489307642,
0.033858440816402435,
-0.03416140004992485,
0.007765073329210281,
0.08494032919406891,
0.03465421870350838,
-0.08393961936235428,
0.20764252543449402,
0.06755644828081131,
0.16799749433994293,
-0.004281574860215187,
-0.06491804122924805,
0.15708070993423462,
0.074548438... |
Experimental Approaches for Exposure to Sized Glass Fibers
1980
David M Bernstein
Robert T Drew
Marvin Kuschnert
Experimental Approaches for Exposure to Sized Glass Fibers
Environmental Health Perspectives
341980
A number of studies have shown that glass fibers induce both malignant mesothelioma and fibrosis in rats and that these reactions may be primarily a function of the physical properties of the fiber. However, these studies were carried out with fibers having broad size distributions and used methods of administration which bear little resemblance to the way man is exposed.To better characterize the health effects of glass fibers, techniques have been developed to expose rats to glass fibers of defined sizes by intratracheal instillation of aqueous suspensions and by "nose only" inhalation exposure, and to determine the deposition, translocation, and ultimate fate of these fibers in the rat. The fibers have known size distributions with geometric mean diameters of 1.5 ,um ((r, = 1.1) and lengths of either 5 ,um (o-, = 1.49) or 60 ,um (a-, = 3.76). The flbers have been activated with neutron irradiation. Of the several resulting radionuclides, 65Zn appeared to be the most suitable for long-term clearance studies by use of in ivo whole body radioassay techniques.A fluidized bed aerosol generator has been developed to expose rats by "nose only" inhalation to approximately 500 fibers/cm3. The generator and exposure system permits reuse of fibers which pass through the exposure chamber and produces no significant alteration of the fiber size distribution. Rats were exposed by intratracheal instillations to 20 mg ofthe longer fibers and to equal numbers (2 mg) and equal mass (20 mg) ofthe shorter fibers. Through approximately 19 weeks little difference was observed in the whole rat clearance rate of long versus short fibers in the initial exposure group. Histopathology, however, showed differences at this time with the short fibers apparently successfully phagocytized by alveolar macrophages and cleared to the lymph nodes, while the long fibers were not.
Introduction
Glass fibers have been shown to induce malignant mesothelioma when introduced directly into the pleural cavity of rats (1). Suspensions of glass fibers have also produced pulmonary fibrosis when instilled into the trachea (2). These studies indicated that such tissue-damaging reactions to fibers may be primarily a function of their geometry, with long (>20 gm), thin (<2 ,um) fibers thought to be the most reactive and shorter (<5 u.m) fibers less active or inactive. However, the studies above, along with most other studies on biological effects of fibers, have used fibers with broad particle size distribu- tAuthor to whom reprint requests should be addressed.
tions with respect to both length and diameter. In addition, the modes of administration bear little resemblance to the way man is exposed, leaving some doubt as to which properties of the fibers caused the fibrosis and mesothelioma.
To better characterize the health effects of fiber glass, a study has been implemented to determine the deposition, translocation, and ultimate fate of fibers of defined size distributions, when introduced into the respiratory tract of rats. The glass fibers have known size distributions with a geometric mean diameter of 1.5 ,um and a length of either 5 or 60 ,um. The rats have been exposed to these fibers by intratracheal instillation of aqueous suspensions and by "nose only" inhalation exposure. While it is recognized that intratracheal instillation bears little resemblance to the way man is exposed, the techniques of inhalation exposure of glass fibers in this study are considerably more complex. Therefore, intratracheal instillation was used as an initial step in February 1980 studying the health effects of known quantities of glass fibers deposited in the lungs of rats. In addition, exposing the animals by both methods affords an opportunity to evaluate the relative merits of intratracheal instillation as compared to nose exposure. This report describes the methods and techniques developed for both routes of exposure, and presents the clearance data and histological results from the intratracheal instillation exposure.
Materials and Methods
Glass Fibers
The fibers, manufactured by Johns Manville, Inc., were either 1.5 x 5 ,um or 1.5 x 60 ,um in size. The 1.5x5,um Environmental Health Perspectives z a wr: IL procedure involved first machining a single die to produce a fiber of 1.5 ,um diameter. After a continuous strand was threaded through a series of channels in an acrylic block, the channels were embedded with methacrylate, and the block cut on a microlathe to various lengths. The acrylic was then dissolved away with methyl ethyl ketone. Residual contaminants were removed by low temperature ashing, followed by further washing of the fibers.
The size distributions of the fibers were determined by the manufacturer by measuring the length and diameter of 600 fibers in each size group. The length size distributions were confirmed in our laboratory to ensure that no breakage of fibers occurred in transportation or handling. The results of these measurements are summarized in Tables 1 and 2. While the length size distributions are not monodisperse, Figure 1 shows that they do not overlap significantly.
Animals
These studies were conducted with male Fisher 344 rats purchased from Microbiological Associates. The animals were approximately 10 weeks old at the time of exposure. They were housed in wire cages, allowed food and water ad libitum, and maintained on a 12-hr light cycle at 22 + 2°C, 50% RH.
Methods
To quantitate the deposition and clearance of the fibers in the rats the fibers were neutron-activated for 18 hr at a flux of -1 x 1014 neutrons/cm2/sec. After the activated fibers decayed for approximately 12 weeks, the longerlived radionuclides 65Zn, 60Co, 152Eu, 46Sc, and 124Sb remained. Of these 65Zn was determined to be the best tracer for the fibers. Leaching studies in saline at 37°C for 24 hr indicated that cobalt is readily removed from the fibers.
The isotopes present in the fibers were assayed by y-ray spectroscopy. The detection system consists of two 6 x 3 in Nal (TI) scintillation crystals multi- plexed into a Tracor Northern 1705 multichannel analyzer. The spectra are stored on magnetic tape and the relative amounts of each radionuclide in the fibers determined with the aid of the computer program PARANA (3, 4) (Pulse Height Analyses for Radionuclide Assay) which performs least squares regression of the multicomponent y-ray spectra. The major components of the glass fibers as determined by the manufacturer and the isotopes detected by instrumental neutron activation analysis are listed in Tables 3 and 4, respectively.
Intratracheal Instillation Exposure. A procedure for the pulmonary instillation of particle suspensions was developed for use in this laboratory. The procedure involves anesthesia of the animal, followed by depression of the tongue and illumination of the deep pharynx with a fiberoptic laryngoscope. A bevelled Teflon tube is inserted into the trachea to a level just cephalic to the first bronchial bifurcation. Injection of the material to be delivered is rapid via a No. 19 gauge hypodermic needle inserted directly into the tracheal tube. Four groups of rats were instilled with fibers as outlined in Table 5.
Rats in group 2 thus were given approximately the same number of fibers as rats in group 1 and rats in group 3 were given the same weight of fiber glass as those in group 1. Initially 4 rats/group were instilled with activated fibers and sacrificed 18 to 20 weeks after exposure. An additional 30 rats/group were then instilled with similar doses of fibers with serial sacrifices of 4 rats/ group beginning at 6 months and extending through two years. Finally, to ensure that any long-term effects are a result of the fibers and not the small amount of radioactivity present in them, an additional 50 rats/group were instilled with nonactivated fibers.
Inhalation Nose Exposure System. Because of the elaborate process involved in manufacturing the fibers to size, only a few grami -ire available for all the exposures in this study. rience special techniques had to be developed to generate high concentrations of fibers in the exposure chamber without breaking the fibers and to conserve the amount of fibers that were available. A miniature fluidized bed aerosol generator and a specially designed exposure chamber shown in Fig-ure 2 were developed. The fibers were ultrasonicated in ethyl alcohol and deposited on a Teflon filter at the bottom of a glass tube (d = ½2 in.). The tube was vibrated, as an airstream was passed up through the filter, creating a fluidized bed of fibers from which individual fibers became airborne. The fiber/airstream was directed through a 85Kr charge neutralizer and into the exposure chamber. The highly polar nature of the glass fibers necessitated a pretreatment with successively nonpolar solvents beginning with ethyl alcohol, methyl ethyl ketone, and finally petroleum ether. This treatment is performed on the fibers in the fluidized bed generator directly before exposure.
The rats were exposed four at a time for 1 hr at a concentration of ca. 500 fibers/cm3 of air. To conserve fibers, the generator was operated in cycles of 1 min on and 40 sec off, with the settling time of the airborne fibers being sufficiently long that little loss occurred by deposition during the off time. The fibers passing through the chamber were collected on a Teflon filter. These fibers were washed as de- Environmental Health Perspectives scribed above and kept for reuse. The size distribution of these fibers has been found to be not significantly different from that of the original fibers (Mann-Whitney Statistic, p < 0.05).
Necropsy. The necropsy procedure for the rats involved anesthesia followed by exsanguination via the descending abdominal aorta. The lungs were then perfused in situ with heparinized isotonic saline through the pulmonary artery, removed, and inflated via an endotracheal tube with glutaraldehyde vapor (20 cm water); and then infused with glutaraldehyde fixation solution through the pulmonary vasculature (20 cm water).
After fixation, the lymph nodes, thymus, and adipose tissue were resected. In addition, the diaphragm, gastrointestinal tract, liver, spleen, kidney, brain, and femur were removed for histological examination and autoradiography to determine the presence of fibers in these tissues.
Tissues were embedded in paraffin, sectioned (6 ,um), mounted on a glass slide, and stained with either hemotoxylin and eosin or Trichrome Blue. The refractive index of the fibers is such that the fibers are invisible in the standard Permount mounting media. When mounted in glycerin, however, the fibers are visible by light microscopy.
Autoradiography. An autoradiographic (ARG) technique was adopted for use in localizing the fibers in the tissues. While it is usually easy to locate large quantities of fibers in the lung, the ARG procedure greatly enhances detection of smaller numbers of fibers in other tissues. The beta particles emitted from the radionuclides in the activated fibers are sufficient to expose in one week's time a Kodak NTB-3 emulsion which has been coated on the histological sections. Single activated fibers were clearly identifiable under the exposed emulsion, as seen in the lung section in Figure 3.
Results
Clearance of Glass Fibers
As noted above, cobalt was the only radionuclide found in the supernatant fraction after the fibers were subjected to a saline leaching procedure. From~~~~~~~~~~~~~~~~~~~~~~~~~. .:.,.
-:: the nuclide clearance data and the leaching data, at least two different subsets of tracer nuclides were postulated to be present in the fibers: those securely bound to or in the fibers that would serve as good tracers for the fibers in the rat and those readily removed from the fibers. The statistical method of factor analysis (5) was applied to the clearance data for the five radionuclides to test this hypothesis. Two independent factors were derived from the data, as can be visualized in Figure 4 senting factor 1 (fiber tracers) and the vertical axis representing factor 2 (the surface leachable contaminants). Cobalt stood alone as a leachable contaminant, and the remainder ofthe radionuclides (Zn, Eu, Sc, and Sb) were all of nearly equal value as tracers for the fibers themselves. Of the elements that were good tracers for the fibers, zinc exhibited the highest activity and was therefore used as a representative tracer for fiber clearance. The glass fiber clearance curves for each group are shown in Figure 5. The relative activity of zinc (normalized to the maximum observed value for each animal) was plotted as a function of time (days) for Environmental Health Perspectives 0-each exposure group with the day of exposure designated as day one. The clearance halftimes for each group as estimated by a one component exponential model and the percent of the initial dose which remained at sacrifice (-114 days) are given in Table 6. An analysis of variance for repeated measures was performed to test whether the clearance curves differed significantly from one another. The results indicated that groups 1 (1.5 x 60 Am, 20 mg) and 3 (1.5
x 5 ,um, 20 mg) were not significantly different from one another, but that group 2 (1.5 x 5 ,um, 2 mg) showed a small but significant difference (p < 0.05) from groups 1 and 3.
Fiber Translocation and Histological Results
The histological results reported here were from one point in time (17-19 weeks). There were four rats per group. It is important to note that no definite statement can be made about the progression of any of the pathological changes observed, only that they existed at that point in time. The histological sec- February 1980 of the fiber burden appeared to lie within these granulomas, with few fibers seen elsewhere in the distal lung. One of the four animals showed a very much milder process than the other three. There was no fibrosis. No long fibers were seen totally phagocytized by macrophages although a few were observed partially phagocytized (Fig. 8). No 60 ,m fibers were observed in the lymph nodes, although a few smaller fibers were observed. Short fibers (1.5 x 5 ,um) at the 2 mg dose produced relatively little alteration in three of the rats, and a mild mononuclear (macrophage) response in the fourth rat. Most of the fibers appeared to lie within the macrophages both in the lung and in the lymph nodes where they occurred in tightly packed clusters.
Short fibers at the 20 mg dose produced a spectrum of alterations with differences between the rats. There were large numbers of fiber-laden interalveolar macrophages. There were small linear and irregular nodular aggregates of fiber-filled mononuclear phagocytes layered along and enclosed within alveolar, respiratory bronchiolar, and alveolar duct walls (Fig. 9). There was no fibrosis. Fibers reached the lymph nodes in large numbers where they could be seen within macrophages. These macrophages were observed in tightly packed aggregates (Fig. 10).
Discussion
At 17-19 weeks after exposure, the major response to the short fibers was to produce macrophage aggregations in the alveoli and lymph nodes. These macrophages contained numerous glass fibers. Except for a few, small, relatively well defined granulomas in the 20 mg group, the 2 mg group produced similar but proportionately less response than the 20 mg group.
The response to the long fibers was notably different. No long fibers were observed in the lymph nodes. It appears that the long fibers did not break extensively. Only a very few pieces of shorter fiber were seen in the lymph nodes; if extensive breakage of the fibers had occurred it is postulated that many more fibers should have been observed.
Few, if any, fibers were found by light microscopy outside the respiratory tissues. The whole rat clearance data would therefore be a good measure of total respiratory (lung and lymph node) clearance. Even though there was an apparent difference in macrophage response to the long versus short fibers, no difference was observed in the total respiratory clearance. This may have been due to the fiber detection system being insensitive to fiber translocation between lung and lymph nodes.
Conclusions
The development of suitable techniques enabled rats to be exposed to glass fibers of defined size by intratracheal instillation and by inhalation (nose) exposure.
Through 17-19 weeks, there was little difference in the whole rat clearance rates of long versus short fibers after exposure by intratracheal instillation. The histopathology, however, showed differences at this time in the rat's response to the long and short fibers. The short fibers were successfully phagocytized by alveolar macrophages and were cleared to the lymph nodes, while the long fibers were not. The long fibers produced a granulomatous response with giant cells that was a characteristic response to many types of foreign bodies.
These studies are continuing with serial sacrifices to be performed at intervals over the rats' lifespan. The progressions of the lesions observed at this time and the further translocation of the glass fibers will better be evaluated with the subsequent results from this study.
Comments on "Experimental Approaches for Exposure to Sized Glass Fibers" William E. Smith (Fairleigh-Dickinson Univ., Madison, N.J. 07940): We have carried out experiments with glass fibers injected into the pleural space of hamsters. No tumors were induced by ordinary insulation-grade fibers about 5 tm in diameter. We have gotten tumors with fibers 1 to 1.5,um in diameter, but only when we used relatively long fibers. With these very thin fibers, we got tumors with preparations containing more than 30%o of fibers longer than 20 jum. We got no tumors with preparations in which only about 2% of fibers were longer than l0,um.
February 1980
*
Medical Department, Brookhaven National Laboratory, Upton, New York 11973. tSchool of Medicine, Health Sciences Center, State University of New York at Stony Brook, Stony Brook, New York 11794.
FIGURE 1 .
1Length distributions of the 1.5 x 5 ,um and 1.5 x 60 ,um glass fibers.
FIGURE 2 .
2Schematic representation of fiber generation and exposure system.
FIGURE 3 .
3.. .... .... ....... .. ...} ..~~~~~~~~~~~~~~~~~~~~~~~~~~~. ... 'jX. ' .. ; t~~~~~~~~~~~~~~~~~~~~~~~~~~~~~M ...l' ... .' *~~~~~~~~~~~~~~~~~~..: :..:. Autoradiography of glass fibers (3 x 10 ,um) in histological section of rat lung.
FIGURE 4 .
4Graphical representation of factor analysis results (factor loading).
FIGURE 5 .
5Clearance of glass fibers following intratracheal instillation.
FIGURE 7 .FIGURE 9 .
79Giant cell; 20 mg, 1.5 x 60 ,um exposure group, 239 X.FiGURE 8: 1.5 x 60 jum fiber partially engulfed by macrophages, 239 x. FIGUREX9. Fiber-laden macrophages; 20 mg, 1.5 x 5-~.m exposue-gu 16 Fiber-laden macrophages; 20 mg, I.S x 5 ,um exposure group, 116 x. FIGURE 10. Tightly packed aggregates of 1.5 x 5 Am fibers in lymph nodes; 20 mg exposure group, 239 x.
Table 1 .
1Manufacturers' fiber size characterization.1.5 x 5 um
1.5 x 60,um
Diameter, Length, Diameter, Length,
,um
,um
Jim
,um
Average
2.08
6.0
1.94
50.8
Geometric mean
2.06
5.7
1.91
43.9
Median
2.08
5.7
1.87
56.0
Standard deviation
0.29
1.8
0.35
24.7
Minimum
0.73
2.0
0.93
5.7
Maximum
3.02
15.2
3.63
224.5
N
600
600
Table 2 .
2Size characterization from fiber study.Geometric
Geometric
N
mean
SD
250
5.1
1.49
500
54
3.76
Table 3 .
3Elemental composition of glass fibers (Johns-Manville Batch JM-753 Glass).Major Components
Content, %
SiO2
63.2
B203
5.4
A1203
5.5
Fe2O3
0.1
Na2O
14.8
K20
1.1
CaO
6.0
MgO
3.1
F2
0.7
S03
0.2
Table 4 .
4Isotopes detected by instrumental neutron
activation analysis 10 days after irradiation
using Ge(Li) detection system.
Isotope
Isotope half life
Sodium-24
15.0 hr
Bromine-82
35.3 hr
Lanthanum-140
40.2 hr
Gold-198
2.7 d
Calcium-47
4.5 d
Lutetium-177
6.7 d
Chromium-51
27.7 d
Cerium-141
32.5 d
Hafnium-181
42.4 d
Iron-59
44.6 d
Antimony-124
60.2 d
Strontium-85
65.2 d
Scandium-46
83.8 d
Zinc-65
243.7 d
Cesium-134
2.06 yr
Cobalt-60
5.3 yr
Europium-152
13.0 yr
Table 5 .
5Instillation of fibers.Fiber size,.
Amount,
Saline,
JAm
F
FF
FFFFmg cm3
Group I
1.5 x 60
20
0.5
Group 2
1.5 x 5
2
0.5
Group 3
1.5 x 5
20
0.5
Group 4
-
0.5
Table 6 .
6Estimates of fiber glass clearance (zinc used as a tracer).Half times,
% remaining
Exposure
one component, at ca. 114 days
group
days
(mean ± S.E.)
Group I
20 mg, 1.5 x 60 jm
35.0
16.3 ± 1.2
Group II
2 mg 1.5 x 5,um
22.5
14.3 ± 7.8
Group III
20 mg, 1.5 x 5 ,um
38.5
14.8 ± 1.6
tioning of thin sections (6 um) often results in the
illusion that the fibers are in one plane or that they
are shorter than would be expected. Microscopic
examination of thick sections reveals that the fibers
are, in general, randomly oriented.
The long fibers (1.5 x 60 am, 20 mg) caused the
development of numerous, sharply demarcated,
relatively large, foreign body granulomata, with
numerous giant cells and fibers (Figs. 6 and 7). Most
A^;
X
B.. e7
404,
m~o,.
* OÑ
The authors wish to thank Mr. Robert Peck and Ms. Patricia Carr for much of the analytical and necropsy work, Mr. James Lehmann for assistance with the intratracheal instillation, and Ms. Gail Schuman for the data management and analysis.We would also like to thank Dr. Philip Kane for evaluating the histological slides; Dr. Daniel Costa for his efforts in developing the instillation, dissection, and necropsy protocols; and Mr. George Schidlovsky for the autoradiography procedures. This work is supported by the Thermal Insulation Manufacturers Association and the United States Department of Energy under Contract No. EY-C-02-0016.
Mechanisms of mesothelioma induction with asbestors and fiber glass. M F Stanton, C Wrench, J. Nat. Cancer Inst. 48797Stanton, M. F., and Wrench, C. Mechanisms of mesothe- lioma induction with asbestors and fiber glass. J. Nat. Cancer Inst. 48: 797 (1972).
The influence of varying lengths of glass and asbestos fibers on tissue response in guinea pigs. G W Wright, M Kuschner, Inhaled Particles. IV, W. H. WaltonLondonPergamon PressWright, G. W., and Kuschner, M. The influence of varying lengths of glass and asbestos fibers on tissue response in guinea pigs. In: Inhaled Particles, IV, W. H. Walton, Ed., Pergamon Press, London, 1977.
Analysis of multi-channel gamma ray spectrometer data with adjustment for gain and baseline discrepancies. B S Pasternack, A Luizzi, Nuclear Instr. Meth. 571%7229Pasternack, B. S., and Luizzi, A. Analysis of multi-channel gamma ray spectrometer data with adjustment for gain and baseline discrepancies. Nuclear Instr. Meth. 57: 229 (1%7).
Some experimental sampling results for regression analysis applied to gamma ray spectrometer data. B S Pasternack, A Luizzi, II. Biometrics. 24353Pasternack, B. S., and Luizzi, A. Some experimental sam- pling results for regression analysis applied to gamma ray spectrometer data, II. Biometrics 24: 353 (1968).
Applied Factor Analysis. R J Rummel, Northwestern University PressEvanston, Ill.Rummel, R. J. Applied Factor Analysis. Northwestern Uni- versity Press, Evanston, Ill., 1977.
| [
0.11107542365789413,
-0.08350612223148346,
0.06683153659105301,
-0.013807917945086956,
0.05636613816022873,
-0.10120107233524323,
0.1874067485332489,
0.1865772306919098,
-0.09097999334335327,
0.21044160425662994,
0.040289588272571564,
0.05115740746259689,
0.1097869873046875,
0.217886358499... |
Combinatorics of Essential Sets for Positroids
2 Jul 2024
Fatemeh Mohammadi
Francesca Zaffalon
Combinatorics of Essential Sets for Positroids
2 Jul 20247A7311E0ABB3950FAD518E6E7A44281FarXiv:2403.09453v3[math.CO]
Positroids are a family of matroids introduced by Postnikov in the study of non-negative Grassmannians.Postnikov identified several combinatorial objects in bijections with positroids, among which are bounded affine permutations.On the other hand, the notion of essential sets, introduced for permutations by Fulton, was used by Knutson in the study of the special family of interval rank positroids.We generalize Fulton's essential sets to bounded affine permutations.The bijection of the latter with positroids, allows the study of the relationship between them.From the point of view of positroids, essential sets are maximally dependent cyclic intervals.We define connected essential sets and prove that they give a facet description of the positroid polytope, as well as equations defining the positroid variety.We define a subset of essential sets, called core, which contains minimal rank conditions to uniquely recover a positroid.We provide an algorithm to retrieve the positroid satisfying the rank conditions in the core or any compatible rank condition on cyclic intervals.
Introduction
Matroids are combinatorial objects introduced to encode the concept of linear dependence arising from vector spaces, graphs, algebraic field extensions, and various other contexts.Positroids form a particularly well-behaved class of matroids.On the combinatorial side, Postnikov has identified several families of objects in bijection with positroids, such as bounded affine permutations, plabic graphs, Grassmann necklaces, and Le diagrams [15].The realization space of a positroid inside the totally non-negative Grassmannian, called a positroid cell, is homeomorphic to an open ball.Positroid cells fit together to form a CW decomposition of the totally non-negative Grassmannian [16].Positroids have also been studied in relation to problems coming from quantum physics, as linear images of some positroid cells define a tiling of the amplituhedron, an object encoding the geometry of scattering amplitudes [2,7,12].
Here, we introduce a new combinatorial description of positroids via ranked essential sets and explain how to derive information about the positroid's structure from them.While many combinatorial objects studied in relation to positroids encode their data implicitly, ranked essential sets provide an intuitive understanding of the positroid's dependencies.These dependencies are succinctly encoded by relying on the cyclic order of the ground set.Additionally, ranked essential sets offer insights into the geometry of the positroid's realization space within the Grassmannian and the totally non-negative Grassmannian.As an example, the dimension of positroid cells can be explicitly computed in terms of the ranked essential sets.
Essential sets were initially introduced by Fulton [8] as objects associated to permutations, to study the degeneracy loci of maps of flagged vector bundles.Their combinatorial characterization and properties were further investigated in [6,5].Their introduction within the context of positroids is due to Knutson [9], who used them in Fulton's original definition, for the subclass of interval rank positroids.These positroids are defined by rank conditions on intervals rather than cyclic intervals.
In this work, we extend the notion of essential sets from permutations to bounded affine permutations.Subsequently, we demonstrate how essential sets not only contain sufficient information to reconstruct the bounded affine permutation but also correspond to maximally dependent cyclic intervals of the positroid.We refer to the essential sets of a positroid, along with their rank, as the ranked essential family of the positroid.The rank of a positroid on any cyclic interval can be computed in terms of the information given by the ranked essential family.Furthermore, we define a subset of this family, known as core, and prove that it gives minimal rank constraints necessary to uniquely define a positroid.
Structure of the paper.In Section 2, we introduce the language of matroids and positroids that we will need, as well as bounded affine permutations and their relation to positroids.In Section 3, we define the diagram of a bounded affine permutation, whose top-right corners are defined to be the essential sets.In Section 3.2, we prove an alternative definition via the rank function.This allows us to prove in Theorem 3.9 that the information encoded in the ranked essential family is enough to uniquely describe a positroid.In Section 3.5, we present an algorithm, Algorithm 1, which constructs, whenever it exists, the bounded affine permutation of a positroid satisfying some rank conditions on cyclic interval.If the initial rank requirements form a ranked essential family, the algorithm is guaranteed to terminate and give the unique solution.The minimal set of rank conditions that will uniquely determine a positroid via Algorithm 1 is introduced in Section 3.4.In Section 4, we give an axiomatic description of positroids in terms of ranked essential families.In Section 5 we describe how ranked essential families characterize realization spaces of positroids.In the last section, Section 6, we show that in the rank 2 case, we retrieve the description provided in [13].
Acknowledgment.F.M. was partially supported by the grants G0F5921N (Odysseus programme) and G023721N from the Research Foundation -Flanders (FWO), the UiT Aurora project MASCOT and the grant iBOF/23/064 from the KU Leuven.F.Z. was supported by the FWO fundamental research fellowship (1189923N) and FWO long stay abroad grant (V414224N).
Preliminaries
We begin this section by recalling the definitions of matroids and positroids.Specifically, we recall two among the various equivalent definitions of a matroid: one through its maximally independent sets, and the other through its closed sets [14].
Definition 2.1 (Basis)
. A matroid M is a pair (E, B) such that E is a finite set, called ground set, and B is a collection of subsets of E, called bases, satisfying:
(B1) B ̸ = ∅; (B2) For every A, B ∈ B and a ∈ A \ B, there exists an element b ∈ B \ A such that (A \ {a}) ∪ {b} ∈ B.
The size of any B ∈ B is called rank of the positroid.
Definition 2.2 (Flats)
. A matroid M is a pair (E, F) such that E is a finite set, called ground set, and F is a collection of subsets of E, called closed sets or flats, satisfying:
(F1) E ∈ F; (F2) If X, Y ∈ F, then X ∩ Y ∈ F; (F3) If X ∈ F and x ∈ E, there exists a unique Y ∈ F such that X ∪ {x} ⊆ Y and there is no Z ∈ F such that X ∪ {x} ⊊ Z ⊊ Y .
We will denote the minimal flat containing a subset S ⊆ E, or closure of S, by ⟨S⟩.
Notation 2.3.Throughout the paper, without loss of generality, we assume E = {1, . . ., n} = [n].The family of cardinality k subsets of [n] is denoted by [n] k .For i ∈ Z, we denote by i mod n its representative in [n].For any i, j ∈ Z, we denote by [i, j] the cyclic interval in [n] from i mod n, to j mod n.For instance, if n = 8, then [7,10] = [7,2] = {7, 8, 1, 2}.We use < to denote the normal ordering on Z and < i to denote the ordering on [n] where i is the smallest element, i.e.
i < i i+1 < i • • • < i n < i 1 < i • • • < i i−1.
We extend this order to Z by defining, for j, k ∈ Z, j < i k if and only if j mod n < i k mod n.
Matroids arise as a generalization of the notion of linear dependency.If a matroid is associated to the dependency behavior of a finite set of vectors in a vector space, it is called realizable.Formally, we have the following definition.Definition 2.4 (Realizable matroid).Let K be a field.A matroid M = ([n], B) is said to be realizable over K if there exist a positive integer k and a k × n matrix M with coefficients in K such that for every
I ∈ [n] k det(M I ) ̸ = 0 ⇐⇒ I ∈ B,
where M I denotes the square k × k matrix whose columns are the columns indexed by I in M .The matrix M is said to be a realizing matrix for M.
A positroid is a matroid realizable over R with a positivity condition.
Definition 2.5 (Positroid).
A positroid is a matroid M which is realizable over R and such that there exists a realizing matrix M for M with non-negative maximal minors.In other words, for every I ∈ [n] k , where M I is as defined in Definition 2.4, we have det(M I ) ≥ 0.
Positroids, along with their combinatorial counterparts, have been subject to extensive research [15].Moreover, they found applications in many problems coming from different branches of science [17].One important example is the study of the amplituhedron, an object encoding scattering amplitudes, quantities of interest in theoretical physics [3].Among the combinatorial objects labeling positroids, bounded affine permutations are of particular interest to us.
Definition 2.6 (Bounded affine permutation). Consider a positive integer n.
A bounded affine permutation of size n is a bijection π : Z → Z satisfying the following conditions for all i ∈ Z:
π(i + n) = π(i) + n and i ≤ π(i) ≤ i + n.
Bounded affine permutations and positroids are in a one-to-one correspondence, as shown in [15].This correspondence is constructed as follows: given a positroid P, we define the associated bounded affine permutation π : Z → Z by
π(i) = min{j ≥ i | i ∈ ⟨[i + 1, . . . , j]⟩} for every i ∈ Z.
In particular, if i is a loop of the positroid, then π(i) = i, and if i is a coloop of the positroid, then π(i) = i + n.Moreover, information on the rank of a positroid on cyclic intervals can be extracted from its associated bounded affine permutation.Indeed, by specializing [11,Theorem 3] to the case of cyclic intervals, we obtain the following result.Proposition 2.7.Let π be a bounded affine permutation of size n and let P be the corresponding positroid.
The rank of P is equal to the number of
i ∈ [n] such that π(i) > n.
The rank of a cyclic interval
[i, j] ⊂ [n] is given by the number of ℓ ∈ [i, j] such that π(ℓ) > j.
Another way to combinatorially verify that a matroid is a positroid is through its associated polytope.
P M = conv(e B | B ∈ B) ⊆ R n
where e B is the indicator vector of B, i.e. e B = i∈B e i , with e i vectors of the standard basis of R n .
Then the following characterization holds.Proposition 2.9 ([1, Proposition 5.6]).A matroid M is a positroid if and only if its matroid polytope P M can be described by the equality (Center) Yellow indicates squares on the same row, strictly to the left of (5,6), while blue signifies the sub-antidiagonal ∆ (5,6) .(Right) Yellow depicts T (3,4) , and green the set of squares P (3,4) .See Notation 3.1.
x 1 + • • • + x n = k and by inequalities of the form ℓ∈[i,j] x ℓ ≤ rk([i, j]) for i, j ∈ [n].
Essential sets and positroids
In this section, we will introduce the notion of essential sets of a bounded affine permutation and study their relations to the positroid associated to the same bounded affine permutation.
Essential sets and bounded affine permutations
Notation 3.1.Consider a k × n array of squares in the plane.We will always consider the rows modulo k, i.e. like a matrix vertically infinitely repeating.The square at coordinates (i, j) corresponds to the square contained in row i and column j of the array.Let R i be the i-th row of the array and A (i,j) be the antidiagonal containing the square (i, j).The sub-antidiagonal ∆ (i,j) of the square (i, j) is the set of squares in the array contained in the antidiagonal starting at the square (i + 1, j − 1) and ending in the first column, with rows considered modulo k.Formally, it is defined as:
∆ (i,j) = {(i + ℓ mod k, j − ℓ) | 0 < ℓ < j}.
If (i, j) = (i, 1), we have ∆ (i,j) = ∅.For a square (i, j), we denote by T (i,j) the set of squares contained in the triangle defined by the horizontal segment on the left of (i, j) and the sub-antidiagonal ∆ (i,j) .We denote by P (i,j) the set of squares to the right of the sub-antidiagonal ∆ (i,j) and contained between the horizontal segment starting to the right of (i, j) and the row starting at the end of ∆ (i,j) .See Figure 1.
Let π be a bounded affine permutation of size n.We associate to it a dotted array as follows: consider an n×(n+1) array of squares in the plane.For each i ∈ [n], place a dot inside the square (i, π(i)−(i−1)), while all other squares remain white.This is well-defined since i ≤ π(i) ≤ i + n.We denote by D(π) the set of squares in the dotted array of π containing a dot, i.e.
D(π) = {(i, π(i) − i + 1) | i ∈ [n]}.
Definition 3.2 (Diagram).
The diagram of the bounded affine permutation π is constructed from the dotted array by shading.Specifically, for every dot in the array, the squares on the same row to the strict left of the dot and in its sub-antidiagonal are shaded.The diagram of π consists of the remaining white squares.
A white square is called a corner if no other white square shares its top-right corner.The essential family E(π) of π is defined as the set of cyclic intervals [i, j] for each white corner (i, j − i + 1) in the diagram of π.Each element in E(π) is referred to as an essential set.Equivalently: Hence, the essential family is given by [4,7], [5,6]}.
E(π) = {[i, j] | (i, j − i + 1) is a corner of the diagram of π} = {[i, j] | i ∈ [n], i ≤ j ≤ i + n, π(i) ≤ j, π −1 (j) ≤ i j, π(i − 1) > j, j + 1 < i π −1 (j + 1)}.E(π) = {[1, 4],
The positroid corresponding to π has rank 3 and can be represented by the point-line configuration in Figure 2 (right).Note that the essential family captures the sets lying on a line and the parallel elements.However, to distinguish between them, we need to know their ranks.
The properties of positroids that can be read through their associated bounded affine permutations can also be observed in their diagrams.Proposition 3.4.Let π be a bounded affine permutation of size n, and P its associated positroid.Then:
1.The rank of P is equal to the number of dots in P (1,n) .
The rank of a cyclic interval [i, j] ⊆
[n] is given by the number of dots in P (i,j−i+1) .
Proof.From Proposition 2.7, the rank of [i, j] is the number of ℓ ∈ [i, j] such that π(ℓ) > j.This is exactly the number of dots in P (i,j) .Definition 3.5 (Ranked essential family).Let π be a bounded affine permutation of order n.We define the ranked essential family E r (π) of π to be the family
E r (π) = (r, [i, j]) | [i, j] ∈ E(π) ∪ {[1, n]}, r = number of dots in P (i,j−i+1) .
Example 3.6.Consider the permutation from Example 3.3.Its ranked essential family is
E r (π) = {(1, [5, 6]), (2, [1, 4]), (2, [4, 7]), (3, [1, 8])}.
Example 3.7.Let U k,n be the uniform matroid of rank k on n elements.The associated bounded affine permutation is defined by
π k,n (i) = i + k, for every i ∈ Z. It is easy to see that the set of corners of its diagram is empty, hence E r (π k,n ) = {(k, [1, n])}.
Essential sets and rank function
The ranked essential family can be interpreted as the rank information of maximally dependent cyclic intervals.Indeed, the essential sets can be constructed from the rank function of the positroid as follows.
Theorem 3.8.Let P be a positroid on [n] of rank k and R the set of pairs (r, [i, j]), such that
• if i ̸ = j, then r = rk([i, j]) = rk([i + 1, j]) = rk([i, j − 1]) = rk([i − 1, j]) − 1 = rk([i, j + 1]) − 1. • If i = j, then 0 = r = rk([i, i]) = rk([i − 1, i]) − 1 = rk([i, i + 1]) − 1. Then E r = R ∪ {(k, [1, n])}.
Proof.Let π be the bounded affine permutation associated to the positroid P.
Let (r, [i, j]) ∈ R. Since rk([i, j]) = rk([i+1, j]), we have π(i) ≤ j. Similarly, since rk([i−1, j]) = rk([i, j])+1 and i−1 ̸ ∈ ⟨i, . . . , j⟩, we have π(i − 1) > j. It remains to prove that π −1 (j) ≤ i j and π −1 (j + 1) > i j + 1. The condition rk([i, j]) = rk([i, j − 1]
) is equivalent to the fact that the number of dots in P (i,j−i+1) and in P (i,j−i) is the same.Then either π(j) = j or π(j) > j.In the latter case, P (i,j−i+1) contains a dot in the last row, which is not part of P (i,j−i) .Hence there must be a dot in P (i,j−i) \ P (i,j−i+1) , i.e. π −1 (j) < i j.It follows that π −1 (j) ≤ i j.Finally, rk([i, j]) = rk([i, j + 1]) − 1 implies that the number of dots in P (i,j−i+2) is one more than the number of dots in P (i,j−i+1) .Note that j + 1 is not a loop, hence π(j + 1) > j + 1, and P (i,j−i+2) contains a dot in the row j + 1, which is not in P (i,j−i+1) .For the equality to hold there must be no dot in P (i,j−i+1) \ P (i,j−i+2) , i.e. π −1 (j + 1)
> i j + 1. It follows that [i, j] is an essential set of π. Conversely, let (r, [i, j]) ∈ E r \ {(k, [1, n])}. By definition, r = rk([i, j]) is the number of dots in P (i,j−i+1) . Moreover, rk([i + 1, j]
) is equal to the number of dots in P (i+1,j−i) , which is equal to the number of dots in P (i,j−i+1) since there is no dot in the first row of this region by definition of essential set.Therefore, rk([i + 1, j]) = r.In the same way, since π(i − 1) > j, the number of dots in P (i−1,j−i+2) is equal to one more than the dots in
P (i,j−i+1) , hence rk([i − 1, j]) = r + 1. Since π −1 (j) ∈ [i, j], if π −1 (j) = j, then j is a loop and rk([i, j − 1]) = rk([i, j]). If π −1 (j) ∈ [i, j − 1]
, then there is a dot in P (i,j−i) \ P (i,j−i+1) as well as one dot in P (i,j−i+1) \ P (i,j−i) , hence rk([i, j − 1]) = rk([i, j]).Finally, since π −1 (j + 1) < i, the squares in the left-most antidiagonal intersecting P (i,j−i+1) do not contain a dot.Hence, rk([i, j + 1]) is given by the number of dots in P (i,j−i+1) plus the number of dots contained in the last row of
P (i,j−i+2) , i.e. rk([i, j + 1]) = r + 1. It follows that [i, j] satisfies the conditions in eq. (1), i.e. (r, [i, j]) ∈ E r .
The rank of a positroid on any cyclic interval can be computed via its ranked essential family as follows.
Theorem 3.9.Let P be a positroid and E r its ranked essential family.For any [i, j] ⊆ [n], we have:
rk([i, j]) = min{r + |[i, j] \ I| | (r, I) ∈ E r ∪ {(0, ∅)}}.
Proof.Denote by m [i,j] the quantity on the right-hand side of the equality.Note that rk(
[i, j]) ≤ m [i,j] . Suppose m [i,j] = |[i, j]| and suppose for contradiction that rk([i, j]) < m i,j = |[i, j]|. Then there exists a circuit C ⊆ [i, j] (a minimally dependent set). Let a = min < i C and b = max < i C and note that [a, b] is such that rk([a, b]) = rk([a + 1, b]) = rk([a, b − 1]). Then there exists an essential set (r, I) with r = rk([a, b]) ≤ |[a, b]|−1 and [a, b] ⊆ I. Note that r +|[i, j]\I| ≤ |[a, b]|−1+|[i, j]\[a, b]| < |[i, j] = m [i,j] .
Hence, we get a contradiction and rk(
[i, j]) = m [i,j] = |[i, j]|. Suppose that m [i,j] = r + |[i, j] \ I| for some essential set (r, I). Again, suppose for contradiction that rk([i, j]) < m i,j . Suppose [i, j]\I ̸ = ∅. Then, there exists a circuit C ⊆ [i, j] with C ̸ ⊆ I. Let a = min < i C and b = max < i C and note that [a, b] is such that rk([a, b]) = rk([a + 1, b]) = rk([a, b − 1]
) and at least one index between a and b is not in I.Then, there exists an essential set (r
′ , J) with [a, b] ∪ I ⊆ J and r ′ ≤ r + |(J ∩ [i, j]) \ I| − 1.
Moreover, we have that:
r ′ + |[i, j] \ J| ≤ r + |(J ∩ [i, j]) \ I| − 1 + |[i, j] \ J| = r + |[i, j] \ I| − 1 < m [i,j] . Finally, suppose [i, j] ⊆ I and that rk([i, j]) < m i,j = r. In particular, r ≤ |[i, j]|. If r = |[i, j]|,
then the same reasoning as in the first case works.Hence, assume that r < |[i, j]|.Let F be the union of circuits contained in [i, j], then
F ̸ = ∅, since rk ([i, j]) < |[i, j]|. Let [a, b] be the smallest cyclic interval containing F . Since rk ([a, b]) = rk ([a + 1, b]) = rk ([a, b − 1]), there exists an essential set (r ′ , J) with r ′ = rk ([a, b]) < |[a, b]| and J ⊇ [a, b]. Then rk ([i, j]) = r ′ + |[i, j] \ J| < r = m [i,j] ,
contradicting the hypothesis of minimality on (r, I).
Since a positroid is uniquely defined by its rank on every cyclic interval, it follows that the ranked essential family of a positroid uniquely determines the positroid.Definition 3.10 (Connected essential set).An essential set (r, [i, j]) ∈ E r is said to be connected if there exist no pairwise disjoint sets (r
1 , [i 1 , j 1 ]), . . . , (r m , [i m , j m ]) ∈ E r such that r = r 1 + • • • + r m + [i, j] \ m a=1 [i a , j a ] and [i, j] ⊇ m a=1 [i a , j a ].
We denote the set of connected ranked essential sets by CE r .Remark 3.11.By definition of connected essential set, it follows that we can rewrite the rank formula from Theorem 3.9 as
rk ([i, j]) = min m a=1 r a + [i, j] \ m a=1 [i a , j a ] such that {(r a , [i a , j a ])} a=1,...,m ⊆ CE r ∪ {(0, ∅)} for every cyclic interval [i, j].
In particular, the rank conditions contained in connected essential intervals are sufficient to reconstruct the positroid.We will show in §3.4 that we can use an even smaller family of minimal rank conditions.
The rank conditions given by connected essential sets define the facets of the corresponding positroid polytope.
Corollary 3.12.Let P be a positroid and let E r be its ranked essential family.Then the positroid polytope of P is given by the facets:
Q P = x ∈ R n | 0 ≤ x i ≤ 1 ∀i ∈ [n], i∈[n] x i = k, ℓ∈[i,j] x ℓ ≤ r ∀(r, [i, j]) ∈ CE r .
Proof.Let P P be the associated positroid polytope.Note that x ∈ P P satisfies all the inequalities defining Q P , hence
P P ⊆ Q P . Let x ∈ Q P and [i, j] ⊆ [n]. By Remark 3.11, we have that rk([i, j]) = m a=1 r a + [i, j]\ m a=1 [i a , j a ] for some pairwise disjoint intervals (r 1 , [i 1 , j 1 ]), . . . , (r m , [i m , j m ]) ∈ E r . Then ℓ∈[i,j] x ℓ = m a=1 ℓ∈[i,j]∩[ia,ja] x ℓ + ℓ∈[i,j]\ m a=1 [ia,ja] x ℓ ≤ m a=1 r a + [i, j] \ m a=1 [i a , j a ] .
Equivalently, we have ℓ∈ [i,j] x ℓ ≤ rk([i, j]).Hence x ∈ P P , as desired.
Properties of essential sets
The ranked essential family contains the non-trivial rank information of a positroid.The elements of this set satisfy compatibility conditions as follows.
Theorem 3.13.Let E r be the ranked essential family of a positroid P of rank k on the ground set [n].
Then, the following holds.
(E1) (k, [1, n]) ∈ E r and for each (r, [i, j]) ∈ E r , we have
|[i, j]| > r ≥ 0 and |[n] \ [i, j]| ≥ k − r > 0. (E2) For every distinct pair (r 1 , [i 1 , j 1 ]), (r 2 , [i 2 , j 2 ]) ∈ E r \ {(k, [1, n])} such that [i 1 , j 1 ] ⊊ [i 2 , j 2 ], we have 0 < r 2 − r 1 < |[i 2 , j 2 ] \ [i 1 , j 1 ]|. (E3) Let (r 1 , [i 1 , j 1 ]), (r 2 , [i 2 , j 2 ]) ∈ E r \ {(k, [1, n])} such that i 2 < i 1 j 2 and j 1 < i 1 j 2 . (1) If [i 1 , j 1 ] ∩ [i 2 , j 2 ] = ∅, i.e. j 1 < i 1 i 2 and j 2 < i 2 i 2 , let (r 3 , [i 3 , j 3 ]) be a minimal essential set containing [i 1 , j 2 ] and (r 4 , [i 4 , j 4 ]) a maximal essential set contained in [j 1 + 1, i 2 − 1]. If there is no such (r 4 , [i 4 , j 4 ]
), then let it be (0, ∅).Then
r 1 + r 2 ≥ r 3 − r 4 − |[j 1 + 1, i 2 − 1] \ [i 4 , j 4 ]|. (2) If [i 1 , j 1 ] ∩ [i 2 , j 2 ] contains [i 2 , j 1 ], i.e. i 2 < i 1 j 1 , let (r 3 , [i 3 , j 3 ]) be a minimal essential set containing [i 1 , j 1 ] ∪ [i 2 , j 2 ] and (r 4 , [i 4 , j 4 ]) a maximal essential set contained in [i 2 , j 1 ]. If there is no such (r 4 , [i 4 , j 4 ]
), then let it be (0, ∅).Then
r 1 + r 2 ≥ r 3 + r 4 + |[i 2 , j 1 ] \ [i 4 , j 4 ]|.
Proof.By construction of the essential family we have that (k, [1, n])
∈ E r . Moreover, if (r, [i, j]) ∈ E r \ {(k, [1, n])}, then 0 ≤ r = rk([i, j]) = rk([i + 1, j]) ≤ |[i, j]| − 1. Let (r 1 , [i 1 , j 1 ]), (r 2 , [i 2 , j 2 ]) ∈ E r be distinct ranked essential sets such that [i 1 , j 1 ] ⊊ [i 2 , j 2 ]. Suppose i 1 − 1 ∈ [i 2 , j 2 ] (similar argument works if j 1 + 1 ∈ [i 2 , j 2 ]), then r 2 = rk([i 2 , j 2 ]) ≥ rk([i 1 − 1, j 1 ]) = rk([i 1 , j 1 ]) + 1 > r 1 , hence r 2 − r 1 > 0.
Moreover, the following relation holds.
r 2 − r 1 ≤ |{dots in P (i 2 ,j 2 −i 2 +1) \ P (i 1 ,j 1 −i 1 +1) }| ≤ |[i 2 , j 2 ] \ [i 1 , j 1 ]|. (2)Suppose [i 2 , j 2 ] ̸ = [1, n]
is an essential set, then the dot in the antidiagonal through (i 2 , j 2 − i 2 + 1) will be in row
h for i 2 < i 2 h < i 2 j 2 . If h ∈ [i 1 , j 1 ]
, then the number of dots in
P (i 2 ,j 2 −i 2 +1) \ P (i 1 ,j 1 −i 1 +1) is strictly larger than r 2 − r 1 . If h ∈ [i 2 , j 2 ] \ [i 1 , j 1 ]
, then the number of dots in
P (i 2 ,j 2 −i 2 +1) \ P (i 1 ,j 1 −i 1 +1) is strictly smaller than |[i 2 , j 2 ] \ [i 1 , j 1 ]|.
Hence, one of the two inequalities from eq. ( 2) is strict, i.e.
r 2 − r 1 < |[i 2 , j 2 ] \ [i 1 , j 1 ]|. Let (r 1 , [i 1 , j 1 ]), (r 2 , [i 2 , j 2 ]
) be as in the assumption of (E3).Let us prove some facts about the rank of the cyclic intervals involved in the statement.Claim 1.There exists an essential set (r, [a, b])
containing [i 1 , j 1 ] ∪ [i 2 , j 2 ] of rank rk([i 1 , j 2 ]). Indeed, if [i 1 , j 2 ] = [1, n], then it is the essential set (k, [1, n]). Otherwise rk([i 1 , j 2 ]) = rk([i 1 +1, j 2 ]) = rk([i 1 , j 2 −1]) is either equal to k, hence [a, b] = [1, n],
or is strictly smaller than k and so [a, b], the maximal set containing [i 1 , j 2 ] with the same rank, will be an essential set.
Claim 2. Suppose i 2 < i 1 j 1 , that is, [i 1 , j 1 ] and [i 2 , j 2 ] intersect in [i 2 , j 1 ]. Let (r, [a, b]) be the maximal essential set contained in [i 2 , j 1 ], then rk([i 2 , j 1 ]) = r + |[i 2 , j 1 ] \ [a, b]|. First note that by Claim 1 there is indeed a unique maximal essential set contained in [i 2 , j 1 ]. Moreover, r + |[i 2 , j 1 ] \ [a, b]| ≤ |[i 2 , j 1 ]|. Suppose there exists an essential set (r ′ , [c, d]) such that r ′ + |[i 2 , j 1 ] \ [c, d]| < r + |[i 2 , j 1 ] \ [a, b]|. Then, by Claim 1 and property (E2), [c, d] ̸ ⊆ [i 2 , j 1 ]. Moreover, [i 2 , j 1 ] ̸ ⊆ [c, d] since otherwise rk([i 2 , j 1 ]) = r ′ , and by Theorem 3.8, [c, d] would be contained in both [i 1 , j 1 ] and [i 2 , j 2 ], hence [i 2 , j 1 ] = [c, d] = [a, b]. Then suppose, without loss of generality, that [i 2 , j 1 ] ∩ [c, d] = [c, j 1 ]. Since r ′ + |[i 2 , j 1 ] \ [c, d]| < |[i, j]|, we have that |[c, j 1 ]| > r ′ and [c, j 1 ] does not contain an essential set. Then rk([c, j 1 ]) = r ′ and [c, d] is contained in [i 1 , j 1 ] ∩ [i 2 , j 2 ]. Hence rk([i 2 , j 1 ]) = r + |[i 2 , j 1 ] \ [a, b]|.
Let us now consider the two cases separately.
(1) Suppose [i 1 , j 1 ] ∩ [i 2 , j 2 ] = ∅.By Claim 1, (r 3 , [i 3 , j 3 ]) has the same rank as [i 1 , j 2 ].Moreover, by Theorem 3.9, rk([
j 1 + 1, i 2 − 1]) ≤ r 4 + |[j 1 + 1, i 2 − 1] \ [i 4 , j 4 ]|. Hence r 1 + r 2 = rk([i 1 , j 1 ]) + rk([i 2 , j 2 ]) ≥ rk([i 1 , j 2 ]) − rk([j 1 + 1, i 2 − 1]) ≥ r 3 − r 4 − |[j 1 + 1, i 2 − 1] \ [i 4 , j 4 ]|. (2) Suppose [i 1 , j 1 ] and [i 2 , j 2 ] intersect in [i 2 , j 1 ]
. Then, by Claim 1 and Claim 2, it follows that
r 1 + r 2 = rk([i 1 , j 1 ]) + rk([i 2 , j 2 ]) ≥ rk([i 1 , j 1 ] ∪ [i 2 , j 2 ]) + rk([i 2 , j 1 ]) = r 3 + r 4 + |[i 2 , j 1 ] \ [i 4 , j 4 ]| for (r 3 , [i 3 , j 3 ]), (r 4 , [i 4 , j 4 ]
) as in the statement.
Remark 3.14.The properties from Theorem 3.13, can be interpreted as follow.
(E1) If (r, I) is a ranked essential set, then the rank is non-negative and the vectors in I are dependent.
(E2) A ranked essential set (r, I) contains all the vectors in the closure of I in the same cyclic interval as I. Hence, if there is a ranked essential set (r 2 , I 2 ) containing I, its rank will be strictly larger and I 2 contains more dependency conditions than the ones in (r, I).
(E3) This condition corresponds to the sub-modular inequality for the rank function:
rk(A) + rk(B) ≥ rk(A ∪ B) + rk(A ∩ B),
in terms of ranked essential sets.
Note that if two essential sets (r
1 , [i 1 , j 1 ]) and (r 2 , [i 2 , j 2 ]) intersect in two cyclic intervals, that is, [i 1 , j 1 ] ∩ [i 2 , j 2 ] = [i 1 , j 2 ] ∪ [i 2 , j 1 ]
, by Theorem 25 of [11], the rank of the intersection is
rk([i 1 , j 2 ] ∪ [i 2 , j 1 ]) = min{r 1 + r 2 − k, r 3 + |[i 1 , j 2 ] \ [i 3 , j 3 ]| + r 4 + |[i 2 , j 1 ] \ [i 4 , j 4 ]|},
where (r 3 , [i 3 , j 3 ]) is the maximal essential set contained in [i 1 , j 2 ] and (r 4 , [i 4 , j 4 ]) is the maximal essential set contained in [i 2 , j 1 ].Hence, no additional condition is required for this case.
In Theorem 4.3, we will show that these properties are sufficient for a family of pairs consisting of a non-negative integer and a cyclic interval to form the ranked essential family of a positroid.
Minimal rank conditions
As seen in the definition of connected essential sets, the rank conditions within the ranked essential family of a positroid are not minimal.To restrict the ranked essential family to minimal conditions, we introduce a constant associated with each essential set.These constants intuitively count the number of additional dependent points in each essential set.We define them inductively as follows.
Definition 3.15 (Excess)
. Let E r be a ranked essential family.For each ranked essential set (r, I) ∈ E r , let
e I = |I| − r − J∈E,J⊊I e J .
The quantity e I is called excess of the essential set I.
If the excess of a set vanishes, it indicates that there is no new information on the dependencies.Hence we give the following definition.Definition 3.16 (Core).Let E r be a ranked essential family.The core C r of E r is the subset given by essential sets with positive excess:
C r = {(r, I) | (r, I) ∈ E r and e I > 0}.
Example 3.17.Consider the positroid from [4, Example 1].P is defined to be the parallel connection of four copies of U 2,3 on {1, 2, 3}, {4, 5, 6}, {7, 8, 9}, {3, 6, 9}, where the parallel connection of matroids is as defined in [14, Proposition 7.1.18].Equivalently, P is the positroid associated to the bounded affine permutation π = (3 10 8 6 13 11 9 16 14).The ranked essential family is (2, [4, 6]), (2, [7, 9]), (4, [3,9]), (4, [6,3]), (4, [9,6]), (5, [1, 9])}.This example illustrates an essential family where the smallest essential set containing the union of two essential intervals is strictly larger than the union.Specifically, the smallest essential set containing [1,3] ∪ [4,6] is [9,6] ⊋ [1,6].In this example, all rank conditions imposed by essential sets are necessary to define P.Moreover, the excess of each essential set is equal to 1 and E r = C r .From the rank constraints on the essential sets, we can recover rk ({3, 6, 9}) = 2 by applying [11, Theorem 25].
E r = {(2, [1, 3]),
Remark 3.18.Let E r be a ranked essential family.If an essential set (r, [i, j]) ∈ E r is disconnected, i.e. there exists pairwise disjoint essential sets (r
1 , [i 1 , j 1 ]), . . . , (r m , [i m , j m ]) ∈ E r such that r = r 1 + • • • + r m + |[i, j] \ a∈[m] [i a , j a ]| and [i, j] ⊇ a∈[m] [i a , j a ], then (r, [i, j]) is not in the core. Indeed e [i,j] ≤ |[i, j]| − r − a∈[m] (|[i a , j a ]| − r a ) = 0.
However, in general the core C r is strictly smaller than the family of ranked connected essential sets CE r .Consider for example the positroid with ranked essential family (2, [3, 5]), (3, [1, 5]), (4, [1,6])}.
E r = {(2, [1, 3]),
Then every essential set is connected but the core is C r = {(2, [1,3]), (2, [3,5]), (4, [1,6])}.Question 3.19.In [6], Eriksson and Linusson introduced the core of for essential sets of permutations and showed that it generally has a much smaller size than the ranked essential family.What can be said about the size of the ranked essential family and of the core for bounded affine permutations?
The retrieval algorithm
Here, we answer the question of how to reconstruct the bounded affine permutation associated to a ranked essential family.The algorithm we provide to answer this question is robust.Indeed, the algorithm outputs a bounded affine permutation whenever the input contains rank conditions on cyclic intervals which are realizable by a positroid.
Definition 3.20 (Proper dotting)
. Consider an n × (n + 1) array of squares in the plane.A subset D of squares in the array is said to be a proper dotting if D contains at most one square in each row of the array and at most one square in each antidiagonal of the array.A proper dotting is called maximal if it contains exactly one square in each row of the array.The rank and the dependency of a square (i, j) with respect to a proper dotting D are defined as follows:
r D (i, j) = |D ∩ P (i,j) | and d D (i, j) = |D ∩ T (i,j) |.
Remark 3.21.A maximal proper dotting of a n × (n + 1) array corresponds uniquely to a bounded affine permutation π of size n, given by π(i) = j + i − 1 for i ∈ [n], where j ∈ [n + 1] is such that (i, j) ∈ D. Hence, a maximal proper dotting defines a positroid.
Description of Algorithm 1.
The algorithm takes as input E r , a subset of the array with non-negative integer labels, containing the required rank conditions.Its objective is to identify, if feasible, a positroid satisfying such rank conditions.In the process, S represents the shaded squares and D contains the position of the dots added to the array at any point during the algorithm.Additionally, the algorithm initializes r to 0.
Consider a labeled square (r, (i, j))
∈ E r . Define a D (i, j) = j − d D (i, j) − r. Let h ∈ [i, j
] be the smallest row, according to the order < i , not containing a dot.We consider two cases:
1.If there exists ℓ ∈ [h + 1, j] such that h is dependent on h + 1, . . ., ℓ, then add a dot in the smallest such ℓ.Repeat this process until no further addition is possible.
2. If no such ℓ exists, then proceed to the next labeled square (r, (i ′ , j ′ )) or increase the label by one.This case occurs if the number of elements in the interval corresponding to the square (i, j) minus the dots already contained in T (i,j) is smaller or equal to r.
Once we have applied the first part to each labeled square, we proceed to fill the remaining rows.Let k be the maximum label, which is usually appearing as the label of (1, n).For each row h not containing a dot, add a dot in the minimal square with rank k, i.e. the minimal ℓ such that ℓ minus the number of dots contained in T (h,ℓ) equals k.The algorithm is formalized in Algorithm 1.
Algorithm 1: Construction of positroid from rank conditions on cyclic intervals
Input: E r a set of pair of integer number and labels for a square in an n × (n + 1) array.
Output: A dotting D of the array.
1 D ← ∅, S ← ∅, r ← 0, k ← max{r | (r, (i, j)) ∈ E r }; 2 E r ← Sorted(E r ) ;
◁ Sort E r by label r in ascending order 3 foreach (r, (i, j)) Remark 3.22.A retrieval algorithm for permutations and their essential sets is given in [5].However, the slightly different definition of essential sets introduced here, requires us to have a completely different approach in the retrieval algorithm.In particular, we use the bijection between positroids and bounded affine permutations to guide our approach.
∈ E r do 4 a ← j − r − d D (i, j); 5 while a > 0 do 6 h ← min < i {α | R α ̸ ⊆ S}; 7 ℓ ← min{β | β − 1 − d D (h, β) = r}; 8 D ← D ∪ {(h, ℓ)}; 9 S ← S ∪ R h ∪ A (h,ℓ) ; 10 b ← j − r − d D (i, j);
Implementation.An implementation of the algorithm can be found at github.com/frazaffa/essential-sets-positroidA visual implementation of the algorithm can be found at the following website.Here the required input is a list of triples, where each triple consists of the rank followed by the row and the column of the square in the array corresponding to the cyclic interval whose rank we want to assign.
Example 3.23.Consider the set of labeled squares E r = {(1, (3, 2)), (3, (1, 5))}.The steps of the algorithm applied to E r can be seen in Figure 3. Hence, the corresponding decorated permutation is π = (5 6 4 7 8).
The algorithm terminates if provided with compatible rank conditions and returns the dotting corresponding to a positroid.This positroid has a rank equal to the maximal label in the given squares and maximal among those satisfying the provided rank conditions.Theorem 3.24.Let E r be a set of labeled squares from an n × (n + 1) array and suppose we have a labeling of the square (1, n).Then Algorithm 1 terminates and outputs a proper dotting if and only if there exists a positroid P satisfying the rank conditions corresponding to the input, i.e. for each (r, (i, j)) ∈ E r , rk([i, j + i − 1]) = r by P and such that the core of P is contained in the rank information encoded in E r .
Proof.Let k denote the label of (1, n).Note that since k denotes the rank of the positroid, if k is not the maximal label, then E r is not valid.
Note that the algorithm always terminates, either with a proper dotting or an error.Indeed, the errors in line 12 and 21 avoid entering an infinite loop and the error in line 28 appears if the produced dotting is not a maximal proper dotting.
(⇐) Suppose the rank conditions in E r can be satisfied by a positroid as in the statement.We want to prove that the output of the algorithm is a proper dotting.Let D be a maximal proper dotting such that r D (i, j) = r for every (r, (i, j)) ∈ E r and the core of the bounded affine permutation corresponding to D is contained in the rank information given by E r .We want to prove that at every step of the algorithm, the dotting D produced is a subset of D.
In the first loop, for each (r, (i, j)) ∈ E r considered in increasing rank order, we add dots inside the triangle T (i,j) , to restrict the rank of [i, j + i − 1] to be at maximum r.Let D be the dotting at this step and suppose D is a subset of D. We enter the loop if j − d D (i, j) > r, that is whenever the number of dots in T (i,j) is not high enough.Since the quantity j − r − d D (i, j) is the excess of [i, j + i − 1], this is equivalent to the requirement that (i, j) corresponds to a cyclic interval in the core of D. Let h be the first empty row starting from i. Since D can be extended to D and r
D (i, j) = r, then h ∈ [i, j + i − 1].
Let ℓ be such that (h, ℓ) ∈ D. Note that r D (h, j + i − h) = r.Indeed the dots that have been added so far D in rows i to i + h − 2 lie inside T (i,j) .Suppose not, let the first dot in rows i to i + h − 2 lying outside of T (i,j) be in square (h 2 , ℓ 2 ), added while considering some square in E r labeled by r 2 ≤ r.
Then i + j − h − d D (h 2 , i + j − h) < r 2 , hence d D (h 2 , i + j − h) > i + j − h − r 2 ≥ i + j − h − r.
Since all the rows between i and h 2 have been filled by assumption with dots inside T (i,j) , this would imply that
d D (i, j) > h − i + i + j − h − r = j − r, against the assumption that a = j − r − d D (i, j) > 0. It follows that r D (h, ℓ) = r and ℓ ∈ T (i,j) . Moreover, ℓ ′ = min{β | β − 1 − d D (h, β) = r} is such that ℓ = ℓ ′
by rank maximality of D. Hence the algorithm does not produce an error and D ∪ {(h, ℓ ′ )} ⊆ D.
In the second for-loop, we add the dots outside of each T (i,j) considered in the first loop.Suppose D is the dotting constructed so far and it is a subset of D and let h be the row we are considering.
Let ℓ ′ = min{β | β − 1 − d D (h, β) = k},
where k is the label of the square (1, n).Then, since for every (r, (i, j)) ∈ E r , d D (i, j) ≥ j − r, ℓ ′ will lie outside of every triangle T (i,j) .This guarantees that the rank of the square (i, j) with respect to the dotting we are constructing is actually equal to r for each (r, (i, j)) ∈ E r .Let ℓ be such that (h, ℓ) ∈ D. By rank maximality of D, r D (h, ℓ) = k and ℓ ≥ ℓ ′ .Moreover, suppose for contradiction that ℓ > ℓ ′ .Then since r D (h, ℓ) = r D (h, ℓ ′ ) = k, D contains a dot in the antidiagonal containing (h, ℓ ′ ) in the rows between h and h + ℓ ′ − 1.This is not possible by definition of ℓ ′ .Hence ℓ = ℓ ′ , the dotting produced is still a subset of D and the algorithm does not produce any error at this step.
Since we assume D to be a maximal proper dotting satisfying the rank conditions in E r and we proved that the dotting D constructed by the algorithm is equal to D, the last two checks will be satisfied by D, hence the algorithm will terminate and output D.
(⇒) Suppose now that the algorithm terminates and outputs a dotting, denoted as D. Note that D must satisfy the rank conditions specified by E r , as the last step in the algorithm checks for this.Moreover, at every step, we choose a row h that does not already contain a dot.As a consequence, at the end of the algorithm, all the boxes will be shaded if and only if no two dots lie in the same antidiagonal.Hence, D is a proper dotting satisfying the rank conditions given in the input; that is, there exists a positroid satisfying rk ([i, j + i − 1]) = r for every (r, (i, j)) ∈ E r .
In particular, it follows that the rank information contained in the core is enough to uniquely recover the positroid.
Corollary 3.25.The rank conditions contained in the core of a positroid P are minimal rank conditions defining P.
Combinatorial characterization of essential sets
The goal of this section is to provide a combinatorial description of essential sets.We aim to introduce combinatorial conditions that guarantee a given set of labeled cyclic intervals can be viewed as the corners of the diagram of a bounded affine permutation.
The following result is a generalization of Theorem 4.1 from [6] to the setting of bounded affine permutations and our definition of the rank of an essential set.We retain the name "chess theorem", which stands for CHaracterization of ESsential Sets.The use of cyclic intervals and bounded affine permutations significantly alters the third condition in the theorem.The rank interpretation of essential sets allows for an elegant proof of the result.We divide its proof into Lemmas 4.1 and 4.2.Lemma 4.1 demonstrates that we can use a family E r satisfying properties (E1), (E2), and (E3) to construct a function on cyclic intervals which shares many properties with the rank function of a positroid.Lemma 4.1.Let E r be a set of cyclic intervals labeled by a non-negative integer satisfying the properties (E1), (E2), and (E3) from Theorem 3.13.Let CI n denote the family of cyclic intervals of [n] and r : CI n → Z be the function defined by:
r([i, j]) = min{|[i, j]|, r + |[i, j] \ I| | (r, I) ∈ E r }.
The function r satisfies the following properties:
(r1) r(I) = r for every (r, I) ∈ E r and the minimum is uniquely achieved by (r, I); (r3): Let [i, j] be a cyclic interval.We will prove (r3) by considering some cases.
(r2) For every [i, j] ∈ CI n , 0 ≤ r([i, j]) ≤ |[i, j]|; (r3) For every [i, j] ∈ CI n \[n], r([i, j]) ≤ r([i−1, j]) ≤ r([i, j])+1 and r([i, j]) ≤ r([i, j+1]) ≤ r([i, j])+1. (r4) [i, j] ∈ CI n is such that r([i, j]) = r([i + 1, j]) = r([i, j − 1]) = r([i − 1, j]) − 1 = r([i, j + 1]) − 1 if and only if (r([i, j]), [i, j]) ∈ E r . Proof. (r1
• If r([i, j]) and r([i − 1, j]) are given by the cardinality of the sets, (r3) holds trivially.
• Suppose r([i, j]) = |[i, j]| and r([i − 1, j]) = r + |[i − 1, j] \ I| for some (r, I) ∈ E r . Then i − 1 ∈ I and r + |[i, j] \ I| ≥ |[i, j]|, hence r ≥ |I ∩ [i, j]|. It follows that r([i − 1, j]) = r + |[i − 1, j] \ I| ≥ |I ∩ [i, j]| + |[i − 1, j] \ I| = |[i, j]| = r([i, j]). Moreover r([i − 1, j]) ≤ |[i − 1, j]| = r([i, j]) + 1. • Finally, suppose r([i, j]) = r + |[i, j] \ I| for some essential set (r, I). Then clearly r([i − 1, j]) ≤ r([i, j])+1. If r([i−1, j]) = |[i−1, j]| then r([i−1, j]) ≥ r([i, j])+1. If r([i−1, j]) = r ′ +|[i−1, j]\I ′ | for some essential set (r ′ , I ′ ) then r + |[i, j]| \ I| ≤ r ′ + |[i, j] \ I ′ | ≤ r([i − 1, j]).
In an analogous way it is possible to show that r([i, j]) ≤ r([i, j + 1]) ≤ r([i, j]) + 1, hence (r3) holds.
(r4): ([i, j]), a contradiction.In the same way we need to have that j ∈ I. Since I is a cyclic interval, it follows that I = [i, j].By (r1), r([i, j]) = r, hence (r([i, j]), [i, j]) ∈ E r .
Suppose [i, j] ⊊ [n] is such that r([i, j]) = r([i + 1, j]) = r([i, j − 1]) = r([i − 1, j]) − 1 = r([i, j + 1]) − 1 holds. Let (r, I) ∈ E r such that r([i, j]) = r + |[i, j] \ I|. Note that by assumption, i − 1, j + 1 ̸ ∈ I, hence I ⊆ [i, j]. Suppose I ̸ = [i, j] and assume that i ̸ ∈ I. Then r([i + 1, j]) ≤ r + |[i + 1, j] \ I| < r + |[i, j] \ I| = r
Suppose now (r, [i, j]) ∈ E r .By (r1), r([i, j]) = r and the minimum is uniquely achieved by (r, I).Hence, for every (r
2 , I 2 ) ∈ E r , r 2 +|[i, j]\I 2 | ≥ r+1 and r([i+1, j]) ≥ r, r([i, j−1]) ≥ r. Since they are both contained in [i, j], it follows that r([i, j]) = r([i+1, j]) = r([i, j−1]) = r. Moreover, r 2 +|[i−1, j]\I 2 | ≥ r+1 and r 2 + |[i, j + 1] \ I 2 | ≥ r + 1, and r + |[i − 1, j] \ [i, j]| = r + 1 = r + |[i, j + 1] \ [i, j]|, hence we can conclude that (r4) holds.
The following result shows that we can use the function defined in Lemma 4.1 to construct a bounded affine permutation, which is a positroid.Lemma 4.2.Let E r be a family of labeled cyclic intervals satisfying (E1), (E2), and (E3) from Theorem 3.13.Let r : CI n → Z be the function defined in Lemma 4.1 and let π : Z → Z be defined as
π(i) = min{j ≥ i | r([i, j]) = r([i + 1, j])},
where [i, j] = {i mod n, . . ., j mod n} for every i ≤ j.Then π is a bounded affine permutation.
Proof.The function π satisfies the properties such that for every i ∈ Z, i ≤ π(i) ≤ i + n and π(i + kn) = π(i) + kn for every k ∈ Z by construction.Hence, it remains to prove that π is a bijection.
Suppose i, j ∈ Z, with i < j, are such that π
(i) = π(j) = ℓ. Then r([j, ℓ]) = r([j + 1, ℓ]) > r([j + 1, ℓ − 1]). By property (r3) of the function r, r([j + 1, ℓ − 1]) = r([j, ℓ]) − 1. We have that r([j, ℓ]) ≥ r([j, ℓ − 1]) ≥ r([j + 1, ℓ − 1]) = r([j, ℓ]) − 1. Suppose the first inequality is strict, then r([j, ℓ − 1]) = r([j + 1, ℓ − 1]
), contradicting the minimality assumption on ℓ.Hence r([j, ℓ]) = r([j, ℓ − 1]).In the same way, r([i, ℓ]) = r([i, ℓ − 1]).Hence there are (r i , I), (r j , J) ∈ E r such that [i, ℓ] ⊆ I, [j, ℓ] ⊆ J and
r i = r([i, ℓ]), r j = r([j, ℓ]). By definition of π(i) = ℓ, it follows that r([i + 1, ℓ − 1]) = r i − 1. Suppose r([i + 1, ℓ − 1]) = r 2 + |[i + 1, ℓ − 1] \ I 2 | for some (r 2 , I 2 ) ∈ E r , then I 2 is contained in [i + 1, ℓ − 1] since if I add i or ℓ, the value of r strictly increases. Then, r 2 + |[i + 1, ℓ − 1] \ I 2 | ≥ r 2 + |I \ I 2 | ≥ r by property (E2), contradicting the assumption. Finally, note that |[i + 1, ℓ − 1]| ≥ |[i + 1, ℓ − 1]| + r ′ − |[j, ℓ − 1]| ≥ r ′ + |[i + 1, ℓ − 1] \ J| = r ′ + |[i + 1, ℓ] \ J| ≥ r.
Hence, we get a contradiction, and the function π is injective.Moreover, since π is bounded and periodic, it follows that π is a bijection.
Finally, by combining the construction from Lemmas 4.1 and 4.2, we obtain the characterization of essential sets of a positroid.This provides an axiomatic description of positroids from this perspective.
Theorem 4.3 (Chess theorem)
. Let E r be a set of cyclic intervals labeled by a non-negative integer.Then E r is the ranked essential family of a positroid if and only if E r satisfies the properties (E1), (E2), and (E3) from Theorem 3.13.
Proof.If E r is the ranked essential family of a positroid, then (E1), (E2), and (E3) hold as shown in Theorem 3.13.
Suppose now E r is family of labeled cyclic intervals satisfying (E1), (E2), and (E3).Let r : CI n → Z be the function defined in Lemma 4.1 and let π : Z → Z be the bounded affine permutation constructed in Lemma 4.2.We want to prove that the positroid P associated to π is such that rk ([i, j]) = r([i, j]) for each cyclic interval [i, j].Then, by Theorem 3.8 and property (r4) from Lemma 4.1, it follows that E r is the ranked essential family of the positroid P. We will prove by induction on the size of the cyclic interval that the rank 'rk ' and 'r' agree on each cyclic interval.For i ∈ [n], we have rk (
[i, i]) = 0 if π(i) = i ⇐⇒ r([i, i]) = 0 1 if π(i) > i ⇐⇒ r([i, i]) = 1.
Suppose now that rk and r agree on each cyclic interval on size smaller than m and suppose by contradiction
[i, j] is such that |[i, j]| = m and r([i, j]) ̸ = rk ([i, j]
).We will consider the following cases:
Case 1. If r([i, j]) < rk ([i, j]
), since both r and rk are satisfying the property (r3) from Lemma 4.1, r(
[i, j]) = r([i + 1, j]), hence π(i) ≤ j. Moreover, rk ([i, j]) = rk ([i + 1, j]) + 1, i.e. i is independent of i = 1, . . . , j, hence π(i) > j and we get a contradiction. Case 2. If r([i, j]) > rk ([i, j]), since rk ([i, j]) = rk ([i + 1, j]), i is dependent on i + 1, . . . , j, hence π(i) < j. Again, consider the two distinct cases. Suppose then that r([i, j]) > rk ([i, j]). Note that since rk ([i, j]) = rk ([i + 1, j]), i is dependent on i + 1, . . . , j, hence π(i) < j. Case 2.1. Suppose π(j) = j, then r([j, j]) = 0 hence there is (0, I) ∈ E r such that j ∈ I. Suppose r([i, j − 1]) = r ′ + |[i, j − 1] \ I ′ | for some (r ′ , I ′ ) ∈ E r ∪ {(0, ∅)}.+ r ′ ≥ r 3 + r 4 + |(I ∩ I ′ ) \ I 4 |. Then r ′ + |[i, j − 1] \ I ′ | ≥ r 3 + r 4 + |(I ∩ I ′ ) \ I 4 | + |[i, j − 1] \ I ′ | ≥ r 3 + |[i, j − 1] \ I 3 |. Hence r([i, j − 1]) = r 3 + |[i, j − 1] \ I 3 | = r([i, j]),
where the last equality holds since j ∈ I 3 .Assume now that I ∩ I ′ ̸ = ∅.Similarly, let (r 3 , I 3 ) be the minimal element in E r containing I ∪ I ′ and let (r 4 , I 4 ) be the maximal element from E r contained in the minimal cyclic interval containing
I ∪ I ′ in [i, j] C, minus I ∪ I ′ . Then by (E3.1), 0 + r ′ ≥ r 3 − r 4 − |C \ I 4 |. Then r ′ + |[i, j − 1] \ I ′ | ≥ r 3 − r 4 − |C \ I 4 | + |[i, j − 1] \ I ′ | ≥ r 3 + |[i, j − 1] \ I 3 |
and as before we get that r([i, j]) = r([i, j − 1]) and we get that r and rk agree on [i, j].Case 2.2.Suppose π(j) > j.Since rk ([i, j − 1]) = rk ([i, j]), by Proposition 2.7, there is some h ∈
[i + 1, j − 1] such that π(h) = j, i.e. r([h, j]) = r([h + 1, j]) = r([h, j − 1]
).By (r4), there exists some (r, I) such that [h, j] ⊆ I and r
= r([h, j]) = rk ([h, j]). Let (r ′ , I ′ ) ∈ E r ∪ {(0, ∅)} be such that r([i, j − 1]) = r ′ + |[i, j − 1] \ I ′ |. Suppose I ∩ I ′ ̸ = ∅,
the other case will be equivalent.Let (r 3 , I 3 ) be the minimal element in E r containing I ∪ I ′ and let (r 4 , I 4 ) be the maximal element from E r contained in
I ∩ I ′ . Then by (E3), r ′ + |[i, j − 1] \ I ′ | = r ′ + |[i, j − 1] \ (I ∪ I ′ )| + |I \ I ′ | ≥ r ′ + |[i, j − 1] \ I 3 | + |I \ I ′ | ≥ r + r ′ − |I ∩ I ′ | + |[i, j − 1] \ I 3 | ≥ r 3 + |[i, j − 1] \ I 3 | + r 4 + |(I ∩ I ′ ) \ I 4 | − |I ∩ I ′ | ≥ r 3 + |[i, j − 1] \ I 3 |. Hence r([i, j − 1]) =
Realization spaces of positroids
We now turn our attention to the realization space of a positroid in the totally non-negative Grassmannian and the Grassmannian.Recall that, given a field K, the Grassmannian Gr(k, n) is the space of all kdimensional linear subspaces of K n .Any point V in Gr(k, n) can be represented by a k × n matrix with entries in K. Let M = (m ij ) be a k × n matrix of indeterminates.For a subset I = {i 1 , . . ., i k } ∈ [n] k , let M I denote the k × k submatrix of M with the column indices i 1 , . . ., i k .The Plücker coordinates of V are p I (V ) = det(M I ) for each I ∈ [n] k .The Plücker coordinates do not depend on the choice of matrix M , up to simultaneous rescaling by a non-zero constant, and they determine the Plücker embedding of Gr(k, n) into P ( n k )−1 .Moreover, any point V ∈ Gr(k, n) can be represented as span{v 1 , . . ., v k } for some K-vector space basis {v 1 , . . ., v k }.
Positroid cells
Let K = R.The totally non-negative Grassmannian Gr ≥0 (k, n) is the subset of Gr(k, n) consisting of points whose non-zero Plücker coordinates have all the same sign.Fix a positroid P on [n] of rank k, defined via its basis B. Then the positroid cell of P is the set: S P = {M ∈ Gr ≥0 (k, n) | M I = 0 if and only if I ̸ ∈ B}.
Each positroid cell S P is a topological cell [15], and moreover, the positroid cells of Gr ≥0 (k, n) glue together to form a CW-decomposition of Gr ≥0 (k, n), as shown in [16].
In the remainder of this section, we study positroid cells.In particular, we are interested in computing the dimension of the cell corresponding to a given positroid.Combinatorial objects in bijection with positroids offer a way to compute the dimension of such cells.Specifically, it is possible to compute the dimension of a positroid cell using bounded affine permutations, as outlined in the following result.The codimension of a positroid cell can be determined from its ranked essential family or its core.
Positroid varieties
Given a rank k positroid on [n], labeled by the bounded affine permutation π, the positroid variety Π π is the Zariski closure of the positroid cell S π inside Gr(k, n).The following result generalizes [9, Proposition 2.3], which states an equivalent result for interval positroid varieties, i.e. positroids defined by rank conditions on intervals.
Proposition 5.5.The positroid variety Π π is defined as a scheme by the rank conditions rk(I) ≤ r for every (r, I) ∈ CE r π , the connected elements of the ranked essential family of P π .
Proof.By Remark 3.11 and Theorem 3.9, the rank of each cyclic interval [i, j] can be computed in terms of the rank of the connected essential sets.Hence, the rank condition for [i, j] is implied by those in CE r .
Small rank positroids
We now focus on rank 2 positroids and show how essential sets coincide with the construction given in [13].Moreover, in this case, essential sets correspond to the circuit closures of the positroids.
Let P be a positroid defined by its flats F and consider the following family: If P is a loopless rank 2 positroid, then F is equal to the family of circuit closures of the positroid.Proposition 6.1.If P is a loopless positroid of rank 2, its ranked essential family E r coincides with F r .
Proof.If P has rank 2, then F r is the family of connected components of the graph associated to the positroid P as constructed in [13,Section 3.2].In [13, Proposition 3.9], it is shown that every element of F r is a cyclic interval, making it an essential set.Conversely, each essential set of rank 1 gives rise to a connected component in the graph associated with the positroid P. Hence, E r = F r .
Definition 2 . 8 (
28
Matroid polytope).Let M = ([n], B) be a matroid.The matroid polytope of M is
Figure 1 :
1
Figure 1: (Left) Yellow represents row R 2 , and pink the antidiagonal A (5,7) passing through (5, 7).(Center)Yellow indicates squares on the same row, strictly to the left of(5,6), while blue signifies the sub-antidiagonal ∆(5,6) .(Right) Yellow depicts T(3,4) , and green the set of squares P(3,4) .See Notation 3.1.
( 1 ) 3 . 3 .
133
Example Consider the bounded affine permutation of size 8, defined by π = (3 4 8 7 6 9 10 13).The diagram of the permutation is depicted in Figure 2 (left).The corners of the diagram are (1, 4), (4, 4), (5, 2).
Figure 2 :
2
Figure 2: The diagram and the point-line configuration corresponding to π from Example 3.3
11 if a = b then 12 return E r is not valid 13 else 14 a 23 D
1112131423
foreach h such that R h ̸ ⊆ S do 19 ℓ ← min{β | β − 1 − d D (h, β) = k}; 20 if ℓ > n + 1 then 21 return E r is not valid 22 else ← D ∪ {(h, ℓ)}; 24 S ← S ∪ R h ∪ A (h,ℓ) ; 25 end 26 end 27 if S ̸ = [n] × [n + 1] then 28 return E r is not valid 29 end 30 foreach (r, (i, ∈ E r do 31 if r D (i, j) ̸ = r then 32 return E r is not valid 33 end 34 end 35 return D;
Figure 3 :
3
Figure 3: Algorithm 1 applied to the labeled squares in blue in the first array.
): Let (r, I) ∈ E r .By property (E1), we have r < |I|.Suppose for contradiction that there exists (r 2 , I 2 ) ∈ E r such that r 2 + |I 2 \ I| ≤ r.By (E2), I 2 neither contains nor is contained by I. Hence, let (r 3 , I 3 ) be a minimal set with the smallest label in E r containing I ∪ I 2 , and let (r 4 , I 4 ) be a maximal set with the largest label contained in I ∩ I 2 .Suppose I and I 2 intersect in a cyclic interval.By (E3),r + r 2 ≥ r 3 + r 4 + |(I ∩ I 2 ) \ I 4 |.Moreover, r 4 + |(I ∩ I 2 ) \ I 4 | + |I \ I 2 | = r 4 + |I \ I 4 | ≥ r 2 + |I \ I 2 |,where the last equality holds by assuming that the minimum of the function r is achieved by (r 2 , I 2 ).Then we can write r + r 2 + |I \ I 2 | ≥ r 3 + r 2 + |I \ I 2 |, hence r ≥ r 3 .Since I ⊊ I 3 , by (E2), this is not possible.Finally, suppose I and I 2 intersect in two cyclic intervals.Then r 2 + |I \ I 2 | = r 2 + |[1, n] \ I 2 | ≥ r 2 + k − r 2 + k > r, where we used (E2).It follows that for every (r 2 , I 2 ) ∈ E r \ (r, I), r 2 + |I \ I 2 | > r, hence (r1) holds.(r2): Property (r2) holds by definition of the function r and condition (E1) on the family E r .
First assume that I ∩ I ′ ̸ = ∅.Let (r 3 , I 3 ) be the minimal element in E r containing I ∪ I ′ and let (r 4 , I 4 ) be the maximal element from E r contained in I ∩ I ′ .Then by (E3.2) 0
r 3 +Remark 4 . 4 .
344
|[i, j − 1] \ I 3 | = r 3 + |[i, j] \ I 3 | = r([i, j]), since j ∈ I 3 .If E ris a family of labeled cyclic interval satisfying (E1), (E2), and (E3) we can recover the bounded affine permutation of the positroid defined by E r by applying Algorithm 1 to E r = {(r, (i, j)) | (r, [i, j + i − 1]) ∈ E r }.
Theorem 5 . 1 (
51
[10, Theorem 3.16]).Let P be a rank k positroid on [n] and let π be the associated bounded affine permutation.The positroid cell S P has codimension ℓ(π) inside Gr ≥0 (k, n), whereℓ(π) = |{(i, j) | i ∈ [n], i < j ≤ i + n and π(i) > π(j)}|is called length of π and it is equal to the number of inversions in π.
Figure 4 :
4
Figure 4: The positroids whose cell lies in the Zariski closure of the cell of the positroid from Example 5.4.The data on the left of each box is the rank, the cyclic interval and the excess of each essential set of the family.On the right, the point-line configuration of the positroid is depicted.
F
r = {(r, F ) | F ∈ F, r = rk(F ) < |F |}.
Proof.Let π be the bounded affine permutation corresponding to the positroid P. By Theorem 5.1, we need to prove that ℓ(π) = (r,[i,j])∈E r e [i,j] (k − r).Consider the dotted array of π and note that the length of π can be computed by looking at the array as:Indeed, every time a dot (i, π(i) − i + 1) is counted in the previous formula, there exists a j < i such that π(j) > π(i), indicating one inversion.Note that, if the dot in row i lies in D(π) ∩ T (j,π(j)−j+1) , then (j, π(j) − j + 1) defines a bounded section of the diagram of π, which is non-empty since it contains the dot (i, π(i) − i + 1).Hence there is a corner, i.e. an essential set inside P (j,π(j)−j+1) .Let (r, I) ∈ E r be such an essential set.The number of dots in the same connected component in the diagram as I is exactly the excess of I, e I .We have to count the dot in the same connected component as the essential set [i, j] as many times as the number of inversions it is contained in, i.e. as many times as the number of h such that (i, j − i + 1) ∈ T (h,π(h)−h+1 .Consider the antidiagonal through the point (i, j − i + 1).On the right side of such a diagonal there are r dots, equal to the rank of[1, n].Among these points, those that satisfy the property described above are the dots not in P (i,j−i+1) .It follows that, if the essential set I has rank r, there are k − r such points.Hence we can write:The last equality in the statement holds because e I > 0 if and only if (r, I) ∈ C r , i.e. it is in the core of the ranked essential family.Example 5.3.• The uniform matroid U k,n of rank k on n elements has, as shown in Example 3.7, essential family given by {(k, [n])}.Hence, the codimension of the corresponding cell is 0. This is indeed the top-dimensional positroid cell in the totally non-negative Grassmannian.• Let P be the positroid from Example 3.3.Its ranked essential family isThe codimension of the corresponding positroid cell is: codimBoundaries of a positroid cellHaving an explicit formula for the dimension, we can study how to construct positroid cells lying in the boundary of the Zariski closure of a given positroid cell via essential sets.In particular, we can construct all of the codimension 1 positroid cells.Example 5.4.Consider the positroid P from Example 3.3, whose ranked essential family is E r = {(1,[5,6]),(2, [1, 4]),(2, [4, 7]),(3, [1, 8])}, and whose positroid cell has codimension 5. Then there are 9 positroid cells of codimension 1 contained in the Zariski closure of S P whose ranked essential families are described in the following table.Each row contains respectively the rank, the cyclic interval, and the excess of the essential set.In particular we can easily characterize positroids in terms of the family of circuit closures.Corollary 6.2.If M is a loopless matroid of rank 2, M is a positroid if and only if F r consists of cyclic intervals.Remark 6.3.The equivalence between essential sets and ranked circuit closures does not hold for positroids of higher rank.For instance, consider the rank 3 positroid with ranked essential family(2, [1, 5]),(2, [5, 2]),(3, [1, 7])}.Then {1, 5} is a circuit of rank 1 which does not appear in E r .Moreover, {1, 2} is not a flat of the positroid, as its closure is given by {1, 2, 5}.Authors' addresses
Positroids and non-crossing partitions. F Ardila, F Rincón, L Williams, Transactions of the American Mathematical Society. 36812016
Grassmannian Geometry of Scattering Amplitudes. N Arkani-Hamed, J L Bourjaily, F Cachazo, A B Goncharov, A Postnikov, J Trnka, 2016Cambridge University Press4
The amplituhedron. N Arkani-Hamed, J Trnka, Journal of High Energy Physics. 102014. 2014
J E Bonin, arXiv:2306.06694A characterization of positroids, with applications to amalgams and excluded minors. 2023arXiv preprint
The size of Fulton's essential set. K Eriksson, S Linusson, The Electronic Journal of Combinatorics. 21995
Combinatorics of Fulton's essential set. K Eriksson, S Linusson, Duke Mathematical Journal. 8511996
C Even-Zohar, T Lakrec, M Parisi, R Tessler, M Sherman-Bennett, L Williams, arXiv:2310.17727Cluster algebras and tilings for the m= 4 amplituhedron. 2023arXiv preprint
Flags, Schubert polynomials, degeneracy loci, and determinantal formulas. W Fulton, Duke Mathematical Journal. 6531992
Puzzles, positroid varieties, and equivariant k-theory of Grassmannians. A Knutson, arXiv:1008.43022010arXiv preprint
Positroid varieties: juggling and geometry. A Knutson, T Lam, D E Speyer, Compositio Mathematica. 149102013
The rank function of a positroid and non-crossing partitions. R Mcalmon, S Oh, The Electronic Journal of Combinatorics. 2712020
Triangulations and canonical forms of amplituhedra: a fiber-based approach beyond polytopes. F Mohammadi, L Monin, M Parisi, Communications in Mathematical Physics. 38722021
Computing positroid cells in the Grassmannian of lines, their boundaries and their intersections. F Mohammadi, F Zaffalon, arXiv:2206.140012022arXiv preprint
Matroid theory. J G Oxley, 2006Oxford University Press3USA
A Postnikov, arXiv preprint math/0609764Total positivity, Grassmannians, and networks. 2006
Matching polytopes, toric geometry, and the totally non-negative Grassmannian. A Postnikov, D Speyer, L Williams, Journal of Algebraic Combinatorics. 3022009
The positive Grassmannian, the amplituhedron, and cluster algebras. L K Williams, ICM 2022International congress of mathematicians 2022. Helsinki, Finland, virtual; BerlinEMSJuly 6-14, 202262023
| [
-0.1660802662372589,
0.050583139061927795,
0.024654075503349304,
-0.10747000575065613,
-0.0567372590303421,
0.007938060909509659,
0.15566924214363098,
0.05080679431557655,
0.06368622928857803,
-0.044570013880729675,
-0.014668482355773449,
0.010460730642080307,
0.09010672569274902,
0.036805... |
ScienceDirect COVID-19 lockdown impact on cognitions and emotions experienced during sexual intercourse ଝ
2021
B Gouvernet brice.gouvernet@univ-rouen.fr
Laboratoire CRFDP
UFR SHS
université Rouen-Normandie
76821Mont-Saint-Aignan cedexFrance
M Bonierbale
CRIRAVS AP-HM, hôpital Ste Marguerite
13009MarseilleFrance
B Gouvernet
M Bonierbale
ScienceDirect COVID-19 lockdown impact on cognitions and emotions experienced during sexual intercourse ଝ
Sexologies
302021Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. Disponible en ligne sur www.sciencedirect.com RESEARCH ଝ La version en français de cet article, publiée dans l'édition imprimée de la revue, est également disponible en ligne: doi: * Corresponding author. (B. Gouvernet).LockdownCOVID-19Sexual emotionsSexual cognitionsAttachment styles
Objectives. -To study the impact of COVID-19 lockdown on cognitions and emotions felt during sexual intercourse by analyzing the responses of 1079 French-speaking subjects (338 men, 741 women, median age: 31 years) who participated in an online survey between April 27 and May 11, 2020. Method. -Negative sexual cognitions (NSC), positive sexual emotions (PSE) and negative sexual emotions (NSE) are assessed using a tool inspired by the Sexual Mode Questionnaire. Data are crossed with sociodemographic indicators, information on lockdown modalities, indices on sex life, information on psychological functioning and sexual satisfaction.Main results. -One third of the participants saw a decrease in the frequency of their sexual activities or in their sexual satisfaction. Changes in NSCs were found in 74.4% of subjects (increase: 38.4%; decrease: 36%). Emotional changes are found in between 50.7% (NSC: increase: 20.2%; decrease: 30.5%) and 60.9% (PSE: increase: 24.6%; decrease: 36.3%) of participants. The effect of lockdown on NSC, NSE, and PSE depends on gender at birth, intensity of depressive symptoms, and attachment styles. Women appear to be more vulnerable to lockdown than men. Insecure or depressed subjects also appear more vulnerable. The lockdown impact also depends on changes in the frequency of physical/digital intercourse during lockdown and the modalities of confinement. Changes in NSC, NSE, and PSE had a significant effect on sexual satisfaction during lockdown. Conclusion. -The lockdown impact on sexual emotions and cognitions is non-negligible and greater than the impact on sexual behaviors. Whether it is positive or negative, it asks about the post-confinement repercussions: what becomes of a positive impact with deconfinement? Will the negative impacts be one-off or will vulnerabilities be expressed over the long-term?
Introduction Context
The first cases of SARS COV-2 coronavirus infection officially appeared in Hubei Province (China) in November 2019. Initially confined to China, the coronavirus disease quickly spread around the world. On January 30, 2020, the World Health Organization (WHO) declared a public health emergency of international concern. On March 11, the outbreak of COVID-19 was declared a pandemic by the WHO. Faced with the exponential increase in cases of COVID-19, many countries have adopted localized or generalized lockdown measures for their populations. In France, the first lockdown began on March 17 and ended on May 11. A second lockdown was started on Friday, October 30 until December 1, 2020. We will focus here exclusively on the impact of the first lockdown.
During this first lockdown, French people were under house arrest. Social interactions had to be limited to the strict minimum. Educational institutions were closed to the physical presence of students. Only stores considered essential were allowed to remain open. Daily recreational outings were only allowed for a maximum of one hour, within one kilometer of the home, alone or only with household members.
The sanitary situation and the lockdown related to coronavirus disease have had a deleterious effect on mental health. The prevalence of mood, anxiety and sleep disorders is higher (Gualano et al., 2020;Pierce et al., 2020;Salari et al., 2020) than commonly observed (Baxter et al., 2013;Fond et al., 2019;Lim et al., 2018). Lockdown impacts were found within the family group (Brown et al., 2020;Günther-Bel et al., 2020) and within the couple (Luetke et al., 2020;Moreira and da Costa, 2020).
While many studies have evaluated the effects of lockdown on well-being and physical and mental health, fewer have examined its effects on sexuality. However, sexuality is an important dimension of health (WHO, 2006) with significant individual and social repercussions (Ford et al., 2019). In order to contribute to this emerging field of research, we propose to study the repercussions of COVID-19 lockdown on the automatic thoughts -cognitions -and emotions experienced during sexual relations, in line with socio-cognitive approaches to sexuality (Byers et al., 1998;Else-Quest, 2014;Nobre and Pinto-Gouveia, 2008;Moyano et al., 2016;Renaud and Byers, 1999;Sprecher, 2014;Tavares et al., 2020;Verbeek et al., 2020). Because sexual satisfaction is associated with mental health and quality of life for individuals and couples (Flynn et al., 2016;Peixoto et al., 2018;Sánchez-Fuentes et al., 2014), we also study the impact of these cognitions and emotions on sexual satisfaction in line with recent international literature (Li et al., 2020;Panzeri et al., 2020).
Literature review
Works on the lockdown impact on sexuality have primarily focused on sexual behaviour: changes in masturbatory practices, lockdown impact on the frequency of sexual intercourse, cybersexuality usage, consumption of pornography (Arafat et al., 2020;Landry et al., 2020;Lehmiller et al., 2020;Mestre-Bach et al., 2020;Stephenson et al., 2020). Overall, these studies show that while the lockdown impact on sexuality exists, it is not unidirectional (Doring, 2020). It depends on a plurality of individual, relational and contextual factors (Dewitte et al., 2020):
• overall, it appears that women are more vulnerable to the effects of lockdown than men. It is explained in particular by greater economic precariousness (Milliken et al., 2020), increased difficulties in accessing essentials products (for example: period product, cf. Crawford and Waldman, 2020) or difficulties in accessing sexual and reproductive care (Burki, 2020), gender norms leading to an asymmetry in the division of labour within the household as well as a higher probability of being confronted with domestic violence (UN Women, 2020); • the lockdown impact also depends on the modalities of lockdown. It cannot be identical depending on whether one has been confined alone or in a couple, with a new partner or with a regular partner (Doring, 2020;Luetke et al., 2020), with or without children (Günther-Bel et al., 2020); • the lockdown impact depends on habitual sexual functioning and the ability to create/innovate in one's sexual life (Jacob et al., 2020;Lehmiller et al., 2020;Lopes et al., 2020). Lockdown then raises the question of the impact of cybersexualities (cf. Doring and Mohseni, 2018).
Among the factors explaining the variability of the lockdown effect, those related to psychological and relational functioning have not yet been fully investigated. In a study published at the end of September 2020 (Panzeri et al., 2020), depressive symptoms and anxiety -evaluated at DDASS-21 -would have had a negative impact on the sexual life of participants during lockdown. This study is based on a limited number of subjects (n = 124). Moreover, the links between emotional disorders and sexuality are complex. While sexuality may be negatively impacted by these, it can be ''used'' by participants to manage negative emotions (Bancroft et al., 2003;Cooper et al., 1998;Meston and Buss, 2007). It, therefore, needs to be supplemented by studies on other samples.
Psychological and relational functioning cannot be reduced to psychopathological symptoms. We can assume, in support of the models proposed in adult attachment theory (Birnbaum et al., 2006;Dewitte, 2012;Gouvernet et al., 2015;Mikulincer and Shaver, 2016;Zayas and Ram, 2009), that the way in which relationships with the intimate partner are thoughts and anticipated contributes to shape the emotions and cognitions felt during sexual relations. In doing so, we can assume that the lockdown impact on sexual thoughts and emotions cannot be the same for different attachment styles. It is likely that for the most secure individualsthose with a positive view of themselves and their relationships with their partners -the cognitive-emotional impact is less intense than for insecure individuals. For insecure individuals, it is also likely that the impact is also different depending on whether the subjects present an anxious (negative self-image but positive partner image), avoidant (positive self-image but negative partner image) or fearful (negative self and partner image) attachment style.
Objectives
The questions addressed in this work are the following: Did lockdown have an impact on the cognitions and emotions experienced during sexual relations? If this is the case, can we highlight individual, relational and/or contextual specificities explaining the lockdown impact on sexual cognitions and emotions? Has the cognitive and emotional lockdown impact influenced sexual satisfaction?
Method General considerations
This research is part of a larger online survey conducted from April 27th to May 11th, 2020. In this survey, a plurality of dimensions and behaviors were identified (sexual motivations, masturbatory behaviors, contraception. . .). In this article, we focus on the response concerning the impact of lockdown on the emotions and cognitions experienced during sexual relations involving a partner(s).
The recruitment of participants was carried out via social networks and relayed by journalists from mainstream news media. The questionnaire was created with Limesurvey software. Data were stored on a secure university server. No information allowing identification was requested. Neither IP addresses nor cookies were recorded. Before being able to access the survey, the participants had to give their electronic assent via a form presenting the context of the research, its objectives, the average time required to respond and the possible repercussions of the research. Prior to the release of the survey, a specialist in sexuality issues, independent of the principal investigators of the research, was asked to review it.
Measures
Evaluation of negative sexual cognitions (NSC)
We investigated the NSC using the items from the Sexual Mode Questionnaire (SMQ), created and validated by Nobre and Pinto-Gouveia (2003). The SMQ allows for the identification of automatic negative sexual cognitions during sexual relations. It consists of 30 items for the male version and 33 items for the female version. For each item, subjects must indicate on a 5-point lickert scale how often they have experimented different thoughts and images (1: never to 5: systematically). The items for the male version are grouped into 5 components: failure anticipation thoughts, thoughts related to erection difficulties, thoughts related to age or body, negative thoughts about sexuality, lack of erotic thoughts. The items in the feminine version refer to 6 categories of negative cognitions: thoughts related to sexual abuse, thoughts of failure and lack of motivation, lack of partner attention, passive sexuality and control, lack of erotic thoughts, negative body image. In the present research, we selected from the SMQ: 15 items for the male version and 18 items for the female version. The choice of items was made on psychometric bases based on the article by Nobre et al. (2003). We selected the three most saturated items for each of the five dimensions of the male SMQ and the three most saturated items for each of the six dimensions of the female SMQ. We created a composite NSC score by averaging the 15 male items for men and the 18 female items for women in order to obtain an overall NSC score. The evaluation of the internal consistency shows the good qualities of this measure, both for the ''usually'' modality and for the ''during lockdown'' modality (all ␣ > 0.70).
Evaluation of the emotions felt during sexual relations (negative sexual emotions [NSE]; positive sexual emotions [PSE])
The SMQ identifies 10 emotions related to sexuality. Of these 10 emotions, 8 are negative sexual emotions (NSE): they have a negative valence (anger, sadness, disillusionment, fear, shame, guilt, feeling hurt) while only two -pleasure, satisfaction -are positive sexual emotions (PSE). In order to counterbalance this imbalance, we added 6 positive emotions (fun, joy, hope, pride, surprise, serenity), inspired by the work of Fredrickson (Fredrickson, 2001). We evaluated the relevance of this two-dimensional conception of sexual emotions using principal component analysis (varimax rotation) after estimating the number of components to be retained using Horn's parallel analysis (Costello & Osborne, 2005). The internal consistency of the two-dimensional scale created was satisfactory (positive emotions: usually: ␣ = 0.83, during lockdown: ␣ = 0.87; negative emotions: usually: ␣ = 0.81, during lockdown: ␣ = 0.84).
Assessment of anxiety level: GAD7
Anxiety was assessed using the General Anxiety Disorder Scale (GAD7, Micoulaud-Franchi et al., 2016;Spitzer et al., 2006). Originally designed to screen for generalized anxiety disorder, the GAD7 can also be used to assess the presence of anxiety disorders of various forms. Subjects respond on a 4-point lickert scale regarding the frequency they have been bothered by 7 problems in the last two weeks. The psychometric qualities of GAD7 have been demonstrated (Johnson et al., 2019). We also find good psychometric qualities (␣ = 0.84). Subjects were categorized as follows: GAD7 < 10: no or few anxiety disorders; GAD7 < 15: moderate anxiety disorders; GAD7 ≥ 15: severe anxiety disorders.
Assessment of depressive symptoms: MDI
We investigated the presence of depressive symptoms using the Major Depression Inventory developed by the WHO (Bech et al., 2001). This questionnaire is composed of 12 items evaluating the frequency of recent depressive symptoms (last 2 weeks) on a 5-point lickert scale. The psychometric qualities reported in the literature are good (Bech et al., 2015), as are those found in the present research (␣ = 0.84). We used the following criteria to discriminate between subjects: no depression or mild depression: MDI ≤ 25; moderate depression: 25 > MDI > 31; severe depression: MDI ≥ 31.
Evaluation of attachment styles: ECR-RS
We assessed the attachment to intimate partner using the Relationship Structures questionnaire of the Experiences in Close Partner Attachment Scale. Relationships-Revised (Chaperon and Dandeneau, 2017;Fraley et al., 2011). It is composed of 9 items presented in the form of proposals. Subjects are asked to indicate their degree of agreement on a 7-point lickert scale. The questionnaire allows 2 scores to be obtained: an anxious attachment score and an avoidance attachment score. The psychometric qualities found in the literature are good. These properties are also good for the present research (anxiety scale: ␣ = 0.85; avoidance: ␣ = 0.73). We categorized subjects according to the classification proposed by Bartholomew and Horowitz (Bartholomew and Horowitz, 1991): subjects for whom both anxiety and avoidance scores were below the median were categorized as having a secure attachment style. Subjects with scores above the median on the anxiety dimension but below the median on the avoidance dimension were categorized as having an anxious attachment style. Subjects with avoidance scores above the median but anxiety scores below the median were considered avoidant. Finally, subjects with scores above the median for both the anxiety and avoidance dimensions were categorized as fearful.
Assessing the frequency of sexual intercourse
We studied the frequency of two types of sexual relations: face-to-face (physical) sexual relations and ''digital'' sexual relations (digitally mediated). For these two behaviors, subjects were asked to indicate, on a 7-point lickert scale (0: never; 6: always), how often they had had sex according 2 modalities: usually and during lockdown.
Assessment of sexual satisfaction
Subjects were asked to rate their sexual satisfaction using a single item presented as a 5-point lickert scale (1: very dissatisfied; 5: extremely satisfied). The value of using a single item to assess sexual satisfaction has already been noted elsewhere (Mark et al., 2014). Participants were asked to respond according 2 modalities: usually and during lockdown.
Statistical data processing and analysis planning
We calculated the number of subjects who experienced an increase, decrease or no change for each of the variables by comparing the response obtained in the lockdown modality with those obtained in the usual modality. Variations in response regarding emotions and NSC were crossed with sociodemographic variables, variables related to lockdown, variables related to sexual life, and variables related to psychological functioning. Statistical analyses were performed using R software. Multivariate analyses were conducted with multinomial regression analyses, which are the extension of logistic analyses to non-binary categorical response. Multinomial regression analyses were also conducted to determine whether emotional and cognitive variations were associated with fluctuations in sexual satisfaction. Fig. 1 presents the lockdown impact on each of the NSC evaluated in this research. At this level of analysis, it appears that all NSC were impacted by lockdown, but to varying degrees. Some of them were mostly increased during lockdown. Others also experienced a significant decrease. For women (Fig. 1a), NSC related to physical appearance or lack of arousal were most likely to increase with lockdown. While abuse-related cognitions decreased for 7.96% (n = 59) of respondents, they increased for 2.16% (n = 16). For men (Fig. 1b), NSC related to lack of arousal and age-related concerns increased the most during lockdown. Examination of the effects of lockdown on each of the PSE and NSC (see Fig. 1c) shows a general trend towards a decrease in emotions experienced, whether positive or negative. At this level of analysis, it appears that PSE were more impacted than NSE, particularly those related to the playful aspects of sexual relations or those related to pleasure and satisfaction. Fig. 2 shows the overall variation in emotion and NSC categories during lockdown. After categorization, the following results can be highlighted:
Results
Participant characteristics
Lockdown impact on sexual emotions and cognitions
• NSC: 25.8% (n = 278) of subjects did not experience changes in NSC during lockdown. For 38.4% (n = 413), NSC increased during lockdown. For 36% (n = 388), they decreased; • NSE: almost half of the subjects did not experience any change in NSE during lockdown (49.3%, n = 532). An increase in NSE was observed for one fifth of the subjects (20.2%, n = 218). For 30.5% (n = 329), they decreased; • PSE: changes in PSE concern 60.9% of participants (n = 657). For nearly a quarter of the subjects, they increased during lockdown (24.6%, n = 265). For more than a third of them, they decreased (36.3%, n = 392). Fig. 3 shows the variation in sexual satisfaction during lockdown. For more than half of the subjects (56.3%, n = 608), lockdown had no effect on sexual satisfaction. The impact was negative for a third of them (33.5%, n = 361). Only 10.2% of subjects (n = 110) experienced an improvement in sexual satisfaction.
Lockdown impact on sexual satisfaction
Identification of protective and risk factors
The multinomials statistical models fit the data ( Table 2). The predictor variables contribute significantly to understand changes in NSC ( 2 (36) = 177, P < 0.001; RN 2 = 0.104),
Sociodemographic variables
Women appear to be more vulnerable to lockdown than men: they experienced more increases in NSC (AOR = A decrease in the frequency of sexual intercourse is significantly associated with both an increase in NSC and NSE and a decrease. The probability that the decrease in the frequency of sexual intercourse has a negative effect on sexual cognitions and emotions is, however, greater than the probability that it has a positive effect (increase in NSC: AOR = 2.355, 95 CI = 1.624-3.414, P < 0.001 vs. AOR = 1.484, 95 CI = 1.001-2.220, P = 0.05; Increase in NSC: AOR = 2.545, 95 CI = 1.741-3.719, P > 0.001 vs. AOR = 1.511, 95 CI = 1.073-2.128, P < 0.018).
Psychological dimensions
Attachment styles. Insecure subjects, whether anxious, avoidant or fearful, were more likely to have experienced an increase in NSE during lockdown compared to secure subjects (anxious: AOR = 2.678, 95 CI = 1.628-4.403, P < 0.001; fearful: AOR = 2.631, 95 CI = 1.678-4.125, P < 0.001; avoidant AOR = 2.137, 95 CI = 1.28-3.568, P = 0.004).
Fearful subjects were particularly vulnerable also cognitively (AOR = 2.771, 95 CI = 1.801-4.266, P < 0.001). The same was true for subjects with an anxious attachment style who, although to a lesser extent, were also cognitively impacted (AOR = 1.704, 95 CI = 1.069-2.717, P = 0.025). Results concerning the cognitive impact of lockdown in avoidant subjects suggest some cognitive vulnerability at ␣<0.00 threshold (AOR = 1.463, 95 CI = 0.931-2.298, P = 0.099).
Fearful subjects were also more likely to experience a decrease in their PSE during lockdown (AOR = 1.633, 95 CI = 1.12-2.38, P = 0.011). Only this attachment style was significantly associated with a change in PSE at the threshold ␣ = 0.05. At the threshold ␣ = 0.00, a trend toward decreased PSE was observed in anxious subjects (AOR = 1.463, 95
Impact of cognitive and emotional changes on sexual satisfaction
The results presented in Table 3 show the impact of variations in NSC, PSE and NGS on changes in sexual satisfaction levels due to lockdown. The statistical model is fitted to the data ( 2 (12) = 310, P < 0.001). NSC, NSE and PSE explain nearly 20% of the variance in changes in sexual satisfaction scores during lockdown (R 2 N = 0.199). An increase in NSC is associated with a decrease in sexual satisfaction during lockdown (AOR = 1.980, 95 CI = 1.335-2.936, P < 0.001). Conversely, a decrease in NSC is associated with increased sexual satisfaction (AOR = 2.718, 95 CI = 1.340-2.956, P = 0.006).
Variations in sexual emotions are also associated with variations in the level of sexual satisfaction. An increase in PSE is associated with an increase in sexual satisfaction (AOR = 4.035, 95 CI = 2.302-7.073, P < 0.001) and a decreased likelihood of decreased sexual satisfaction (AOR = 0.599, 95 CI = 0.379-0.947, P = 0.028). The relationships appear to be more complex for NSE. A change in NSE, either an increase or a decrease, is associated with a decrease in sexual satisfaction (respectively: AOR = 2.395, 95 CI = 1.624-3.532, P < 0.001 and AOR = 1.706, 95 CI = 1.182-2.463, P = 0.004 respectively).
Discussion
This work finds a certain number of results in the literature, either concerning the lokckdown impact on sexual life, concerning female vulnerabilities or concerning the effect of psychopathological symptoms. Following the work on adult attachment, we also find that insecure subjects appear more fragile than secure ones. This work underlines the richness of the cognitive and emotional components of sexual and dual relationships. The impact of lockdown on sexuality is manifest and global. If it concerns behaviors, sexual satisfaction and emotions, it concerns first the thoughts experienced during sexual relations. While the restriction of sexual relations due to physical distancing can be a factor of vulnerability, as noted elsewhere (Doring, 2020;Lopes et al., 2020), the living experience of sexual relations has been impacted, independently of the fluctuations in the frequency of sexual relations, which have been statistically controlled in statistical analyses. These thoughts and emotions experienced during sexual intercourse in turn affected the satisfaction experienced. Some subjects were weakened by lockdown. For others, although fewer in number, lockdown has fostered a richer or more fulfilling sexuality, promoting the construction of new intimacy (Jacob et al., 2020;Lehmiller et al., 2020;Lopes et al., 2020). In particular, we find that the increase in digital sex has contributed to minimizing the likelihood of NSE. Cybersexuality is therefore not de facto pathological or synonymous with risky behaviour, contrary to the still dominant representations (Doring and Mohseni, 2018). However, attention must be paid to the possible long-term repercussions of these digital relationships. If they promote a better knowledge of oneself and the other and allow the maintenance of dual relationships in times of lockdown, they raise the question of the future of cyber-exchanges: risk of diffusion of contents outside the private sphere (e.g. revenge porn), harassment, blackmail and digital scams (Doring and Mohseni, 2018).
Consistent with the literature, women appear to be more vulnerable than men: they were 1.6 times more likely than men to have an increase in NSC and 1.49 times more likely to have an increase in NSE. It is unlikely that this result can be explained by an intrinsically feminine biological vulnerability. Indeed, the literature has struggled to find consistent gendered differences in the frequency of NSC or sexual emotions (Byers et al., 1998;Else-Quest, 2014;Fisher et al., 2012;Moyano et al., 2016;Renaud and Byers, 1999;Verbeek et al., 2020). Because depression affects women more than men (Lim et al., 2018;Fond et al., 2019), the hypothesis that our female population is more prone to depressive symptoms could be raised. However, the levels of depression were controlled for in the statistical analyses. It is therefore more likely that this result reflects a differential impact of lockdown in women and men as suggested in the literature on the gendered impact of lockdown (Burki, 2020;Crawford and Waldman, 2020;Milliken et al., 2020;UN Women, 2020). This impact is to be thought both in its interpersonal aspect -as evidenced by the increase in cognitions associated with a lack of attention from the partner for 20% of women participants -and/or in its sexual aspect -a quarter of women participants report a decrease in their level of arousal during lockdown. This impact is also to be thought at an intra-individual level via the question of negative concerns related to self-image and body image. Indeed, these cognitions increased for more than a third of the women in our study. These female vulnerabilities should not, however, hide the impact of lockdown on men, who also show a decrease in their level of arousal during lockdown as well as an increase in NSC linked to an anticipation of potential failures or age-related NSC.
Following the study by Panzeri et al. (2020), depressive symptoms have a negative impact on sexuality. It manifests itself here by a potentiation of NSE. It is also observed, although in a tendential way (P < 0.10), at the level of the CSNs and the PSE. The results concerning anxiety symptoms are more paradoxical: moderate anxiety symptoms seem to play a salutary role by decreasing the probability of negative emotional experiences. It is possible that, for moderately anxious subjects, sexuality was a means of coping with anxiety about the sanitary situation. Such an interpretive hypothesis would lead to further investigation of the functions of sexuality for these subjects in order to understand what motivated them to have sex during lockdown. In this regard, the Meston and Buss YSEX inventory (Meston and Buss, 2007) could be useful. Such an investigation could be all the more necessary since links between sexuality mobilized to cope with aversive situations is significantly associated with an increased likelihood of risky sexual behaviour (Cooper et al., 1998).
By investigating the links between attachment style and sexual life in a French-speaking population, this research was part of an emerging field of study in France. In continuity with other studies (Birnbaum et al., 2006;Dewitte, 2012;Gouvernet et al., 2015), we find that the sexual life of insecure individuals was more affected by lockdown than the sexual life of secure ones. In line with the theoretical models of adult attachment (Mikulincer and Shaver, 2016), it emerges that these vulnerabilities are not identical according to the type of attachment insecurity. Thus, a hierarchy of psychological vulnerabilities can be highlighted according to the types of attachment: fearful subjects -both anxious and avoidant -were more vulnerable than anxious subjects, who were more fragile than avoidant subjects.
Among the three insecure attachment categories, avoidant subjects appear to be the least vulnerable, since the impact is illustrated only by an increase in NSC. However, we note a tendency (P < 0.10) to an increase in negative cognitions as well as a trend increase in PSE during lockdown. This last point suggests that the lockdown may have led to emotional ambivalence for them. The fact that avoidants tend to favour interpersonal distance and emotional detachment probably explains the potential positive impact on the PSE: by being confined they were able to minimise their social interactions.
By favouring a categorical approach to attachment styles (Bartholomew and Horowitz, 1991), we were able to observe important and specific vulnerabilities of fearful subjects. These results underline the need to take into account the effects of interactions between the anxious and avoidant dimensions of partner attachment, in line with the proposals of Zayas et al. (Zayas and Ram, 2009). If fearful subjects are as vulnerable as anxious subjects with regard to negative sexual emotions, they seem more vulnerable than anxious subjects on the cognitive level. Furthermore, the fearful style is the only attachment style that has an increased likelihood of a decrease in PSE during lockdown.
Anxious and fearful subjects were vulnerable both emotionally and cognitively. Moreover, ambivalence/dissonance was observed on the cognitive level for these two groups of subjects who presented, jointly, an increased probability of increasing negative cognitions and an increased probability of decreasing them. Because these two groups of subjects are specified by a high level of anxiety, it is likely that this cognitive dissonance results from attachment anxiety. Attachment anxiety is characterized by an ambivalent approach to sexuality, used as a means of experiencing the quality of the bond to the partner and to compensate for a negative self-image that intensifies the fear of being abandoned (Dewitte, 2012). Lockdown may have had a positive impact on anxious subjects by allowing them to be with their partner on a daily basis and thus meet their need for closeness. However, the promiscuity imposed for several weeks, combined with the anxious subjects' constant need for reassurance, may also have been a source of tension within the couple (Luetke et al., 2020) by increasing their fears of not living up to the other's expectations. The constant need for closeness and reassurance may have been confronted with a decrease in the partner's desire for sexual relations. Fears in anticipation of lockdown experienced as an anticipation of abandonment may also have emerged. These explanatory hypotheses call for increased attention to the individual and dyadic impact of lockdown but also to the effect of delockdown on individual and inter-individual functioning.
Limitations of the study
Several limitations of this study need to be recognized. The information form sent to the participants before they took part in the research described the context and objectives of the study and targeted people living their lockdown in France. However, it is possible that other participants, French-speakers but non-residents of France, may have wished to take part in the study. Also, we did not assess whether our participants had themselves been affected by COVID-19, either directly or indirectly as a relative of an infected person. It is also possible that some of the participants may have been health care providers or relatives of health care providers, which could have impacted sexual cognitions and emotions, for example through fear of infecting one's partner. Like other studies, our sample is predominantly female. Similarly, like other studies that have investigated the lockdown impact, this research was based on a web-survey data collection, which resulted in a selection bias in our sample. Only those with Internet access and comfortable with computers participated. This potentially excluded people living in geographic areas of ''digital deserts'' or older audiences who may be less comfortable with computers or social networking.
The calls for participation involved a specific audience corresponding to a media target in a category of mainstream press. We find a higher prevalence of anxiety and depressive disorders than is commonly observed (Baxter et al., 2013;Lim et al., 2018;Fond et al., 2019). This prevalence is, however, lower than that found in work questioning the psychopathological impact of the health situation (Salari et al., 2020). It is therefore possible that our subjects belong to a segment of the population that is less vulnerable than the average. The context in which the subjects had to answer the questionnaires must also be considered. Given the lockdown, it is likely that the subjects responded to the questionnaires from their place of residence. However, for nearly 80% of them, they were confined as a couple. Therefore, they agreed to give us their testimonies about their sexual life even though their partner could be present. These constraints, intrinsically linked to the situation of lockdown, prevent us from having de facto access to people for whom the relationship with their partner could be very conflictual.
The impact of nine variables on CSN, ESN and ESP was studied. However, other factors, not considered in this research, may also have had an impact on sexual cognitions and emotions. It would also have been interesting to consider the impact of possible difficulties in accessing contraception or sexual risk reduction. In the same way, if we studied variations in the frequency of physical or digital sexual relations, it would also have been interesting to consider the existence and impact of situations involving extra-marital partners.
These limitations should prompt us to be cautious about generalizing our results to other contexts. However, even within this atypical sample, potentially shielded from the most negative lockdown impact, the implications of lockdown for psychological and sexual health are numerous. However, it is possible that these impacts may be underestimated due to the characteristics of our sample.
Conclusion
The impact of COVID-19 lockdown on sexuality is complex. It is not simply a situation that is passively experienced. It has to be thought out taking into account the specificities of the situation, individual peculiarities, dyadic functioning and gender norms. Therefore, a psycho-sexological accompaniment will have to be based on a bio-psycho-social approach. The post-lockdown psycho-sexological accompaniment will gain by taking into account the thoughts and emotions felt during sexual intercourse as well as the behavioral modifications induced by the lockdown. The investigation of the cognitive-emotional lockdown impact on sexuality will be all the more important as:
• sexuality is an important component of health (WHO, 2006), affecting both individuals and societies (Ford et al., 2019); • negative sexual cognitions and emotions are associated with increased levels of sexual difficulty (Nobre and Pinto-Gouveia, 2008;Tavares et al., 2020); • sexual cognitions and emotions affect sexual satisfaction;
• that sexual satisfaction is associated with mental health and individual and couple quality of life (Flynn et al., 2016;Peixoto et al., 2018;Sánchez-Fuentes et al., 2014).
The proposed accompaniment should make it possible to evaluate the negative effects of lockdown but also its potential positive effects. In this regard, the investigation of sexual creativity during lockdown, especially through the use of new technologies, may be proposed.
Whether positive or negative, the repercussions of lockdown on sexuality and the life of the couple should be considered: what will become of a positive impact with deconfinement? Will the negative repercussions be one-off or will the vulnerabilities be expressed over the long-term?
Disclosure of interest
The authors declare that they have no competing interest.
Figure 2
2Lockdown impact on emotions and cognitions by categories.
Figure 3
3Lockdown impact on sexual satisfaction. changes in NSE ( 2 (36) = 149, P < 0.001; RN 2 = 0.090), and changes in PSE ( 2 (36) = 224, P < 0.001; RN 2 = 0.13).
Table 1
1Participants' characteristics.Total
n
%
Table 1
1presents the characteristics of participants (n = 1079). Our sample is predominantly female (68.7%, n = 741). Nearly 4 out of 5 participants are under 40 years old (79.2%, n = 855), 79.3% of them were confined in couples (n = 856). One third (33%, n = 356) of participants were confined in the presence of children. For a third of the participants (33.7%, n = 364) the frequency of physical sex decreased during lockdown. The frequency of increased digital sex increased almost as much as the frequency of decreased digital sex (9.3% [n = 100] vs. 8.1 [n = 87]). Eightyfour percent of subjects (n = 906) had no or minor anxiety disorders (GAD7 < 10) and 4.9% had major anxiety disorders (GAD7 > 15). In all, 80.4% (n = 868) of subjects have no depressive disorder or only minor depressive disorderFigure 1 Lockdown impact cognitions and emotions (all emotions and cognitions).(MDI < 25); 10.6% (n = 114) have major depressive disorder (MDI > 30). More than a third of subjects were categorized as having a secure attachment to their partner (34.4%, n = 371). More than a quarter of the subjects (27.4%, n = 296) have a fearful attachment. Anxious or avoidant profiles represent less than a fifth of the subjects (respectively: 19.7% [n = 213] and 18.4%[n = 199]).
Table 2
2Sexual cognitions and emotions: multinomial regressions.Negative cognitions
Negative emotions
Positives emotions
Increasing AOR
[95 CI], P-value
Decreasing AOR
[95 CI], P-value
Increasing AOR
[95 CI], P-value
Decreasing AOR
[95 CI], P-value
Increasing AOR
[95 CI], P-value
Decreasing AOR
[95 CI], P-value
Age (ref = 18-24 yo)
25-29
0.828
[0.509-1.348],
P: 0.449
0.802
[0.487-1.319],
P: 0.384
1.399
[0.848-2.306],
P: 0.189
1.145
[0.747-1.755],
P: 0.535
1.13
[0.698-1.83],
P: 0.619
1.368
[0.879-2.13],
P: 0.165
30-39
1.109
[0.679-1.814],
P: 0.679
1.185
[0.723-1.941],
P: 0.502
1.361
[0.822-2.253],
P: 0.231
1.256
[0.827-1.908],
P: 0.284
1.317
[0.813-2.134],
P: 0.264
1.755
[1.135-2.713],
P: 0.011
40-49
0.614
[0.337-1.120],
P: 0.112
0.733
[0.407-1.322],
P: 0.302
1.224
[0.65-2.304],
P: 0.531
1.077
[0.635-1.829],
P: 0.783
0.744
[0.404-1.37],
P: 0.342
1.153
[0.669-1.987],
P: 0.608
50+
0.492
[0.208-1.163],
P: 0.106
0.775
[0.352-1.710],
P: 0.528
1.868
[0.816-4.272],
P: 0.139
0.499
[0.202-1.235],
P: 0.133
1.162
[0.49-2.757],
P: 0.733
1.597
[0.738-3.457],
P: 0.235
Gender at birth (ref = male)
Female
1.609
[1.123-2.306],
P: 0.010
1.191
[0.838-1.693],
P: 0.329
1.487
[1.001-2.21],
P: 0.049
1.145
[0.831-1.578],
P: 0.406
1.195
[0.825-1.729],
P: 0.346
1.039
[0.747-1.446],
P: 0.819
In couple during lockdown
Yes
1.828
[1.187-2.816],
P: 0.006
0.871
[0.583-1.300],
P: 0.498
1.101
[0.711-1.706],
P: 0.667
0.874
[0.606-1.261],
P: 0.472
0.671
[0.446-1.012],
P: 0.057
1.299
[0.881-1.915],
P: 0.187
Children during lockdown (ref = no)
Yes
0.769
[0.504-1.173],
P: 0.222
0.743
[0.490-1.127],
P: 0.163
1.03
[0.66-1.608],
P: 0.897
0.87
[0.597-1.269],
P: 0.469
1.01
[0.655-1.555],
P: 0.965
0.844
[0.574-1.24],
P: 0.387
Physical intercourse (ref = no change)
Increase
0.886
[0.560-1.404],
P: 0.607
3.012
[2.006-4.523],
P: < 0.001
1.068
[0.66-1.729],
P: 0.788
1.851
[1.297-2.639],
P: < 0.001
3.746
[2.556-5.488],
P: < 0.001
0.71
[0.457-1.102],
P: 0.127
Decrease
2.355
[1.624-3.414],
P: < 0.001
1.484
[1.001-2.200],
P: 0.050
2.545
[1.741-3.719],
P: < 0.001
1.511
[1.073-2.128],
P: 0.018
1.397
[0.912-2.139],
P: 0.124
3.305
[2.373-4.601],
P: < 0.001
Digital intercourse (ref = no change)
Table 2 (
2Continued) Negative cognitions
Negative emotions
Positives emotions
Increasing AOR
[95 CI], P-value
Decreasing AOR
[95 CI], P-value
Increasing AOR
[95 CI], P-value
Decreasing AOR
[95 CI], P-value
Increasing AOR
[95 CI], P-value
Decreasing AOR
[95 CI], P-value
Increase
1.136
[0.587-2.198],
P: 0.704
1.458
[0.785-2.709],
P: 0.233
0.837
[0.411-1.706],
P: 0.625
2.193
[1.304-3.686],
P: 0.003
1.367
[0.769-2.431],
P: 0.286
0.771
[0.425-1.399],
P: 0.393
Decrease
1.665
[0.906-3.062],
P: 0.101
1.412
[0.760-2.624],
P: 0.276
1.384
[0.795-2.413],
P: 0.25
1.251
[0.761-2.058],
P: 0.377
1.401
[0.795-2.469],
P: 0.243
1.336
[0.796-2.243],
P: 0.273
GAD7 (ref = GAD < 10)
<15
1.096
[0.604-1.990],
P: 0.763
1.189
[0.649-2.175],
P: 0.575
1.459
[0.838-2.541],
P: 0.182
1.705
[1.029-2.823],
P: 0.038
0.586
[0.318-1.079],
P: 0.086
1.075
[0.656-1.762],
P: 0.774
>15
0.645
[0.276-1.508],
P: 0.312
0.969
[0.409-2.297],
P: 0.943
0.717
[0.339-1.515],
P: 0.383
0.538
[0.239-1.213],
P: 0.135
0.352
[0.122-1.017],
P: 0.054
1.419
[0.695-2.896],
P: 0.336
MDI (ref = MDI < 25)
<30
1.716
[0.919-3.203],
P: 0.090
1.238
[0.642-2.385],
P: 0.524
2.588
[1.503-4.457],
P: < 0.001
1.077
[0.618-1.88],
P: 0.793
1.296
[0.693-2.424],
P: 0.418
1.586
[0.938-2.683],
P: 0.085
>30
1.644
[0.856-3.160],
P: 0.135
1.159
[0.589-2.280],
P: 0.669
3.187
[1.772-5.73],
P: < 0.001
1.446
[0.809-2.584],
P: 0.213
1.609
[0.844-3.068],
P: 0.148
1.444
[0.828-2.521],
P: 0.196
ECR-RS (ref = secure)
Anxioux
1.704
[1.069-2.717],
P: 0.025
1.605
[1.012-2.544],
P: 0.044
2.678
[1.628-4.403],
P: < 0.001
1.481
[0.989-2.219],
P: 0.057
1.349
[0.852-2.137],
P: 0.202
1.463
[0.961-2.229],
P: 0.076
Fearful
2.771
[1.801-4.266],
P: < 0.001
1.959
[1.270-3.024],
P: 0.002
2.631
[1.678-4.125],
P: < 0.001
1.29
[0.89-1.869],
P: 0.179
1.189
[0.776-1.82],
P: 0.426
1.633
[1.12-2.38],
P: 0.011
Avoidant
1.463
[0.931-2.298],
P: 0.099
1.211
[0.775-1.893],
P: 0.401
2.137
[1.28-3.568],
P: 0.004
1.381
[0.92-2.073],
P: 0.119
1.517
[0.96-2.398],
P: 0.075
1.388
[0.904-2.131],
P: 0.134
Overall model's statistics
2 (36)
177
149
224
P-value
<0.001
<0.001
<0.001
R 2 N
0.104
0.090
0.130
GAD7: General Anxiety Disorder scale; MDI: Major Depression Inventory; ECR -RS: experiences in close relationships -revised scale (attachment styles); yo: years-old. Significant at
P < .05 in bold; marginaly significant (P < .10) are underlined
Table 3
3Sexual satisfaction: multinomial regressions.Change in sexual satisfaction (multinomial regression)
Increase AOR [95 CI], P-value
Decrease AOR [95 CI], P-value
Negative cognitions (ref = no change)
Increase
1.725 [0.807-3.689], P = 0.160
1.980 [1.340-2.956], P < 0.001
Decrease
2.718 [1.340-5.513], P = 0.006
1.082 [0.706-1.660], P = 0.715
Negative emotions (ref = no change)
Increase
1.323 [0.653-2.679], P = 0.436
2.395 [1.624-3.532], P < 0.001
Decrease
1.615 [0.964-2.705], P = 0.068
1.706 [1.182-2.463], P = 0.004
Positive emotions (ref = no change)
Increase
4.035 [2.302-7.073], P = < 0.001
0.599 [0.379-0.947], P = 0.028
Decrease
1.043 [0.506-2.149], P = 0.909
3.085 [2.187-4.351], P = < 0.001
Overall model's statistics
2 (12)
310
P-value
<0.001
R 2 N
0.199
CI = 0.961-2.229, P = 0.076) and an increase in PSE for
avoidant participants (AOR = 1.517, 95 CI = 0.96-2.398,
P = 0.075).
Depression. The intensity of depressive symptoms is
mainly associated with fluctuations in NSE (moderate
depression [26 < MDI < 30]: AOR = 2.588, 95 CI = 1.503-4.457,
P < 0.001; severe depression [MDI > 30]: AOR = 3.187, 95
CI = 1.772-5.73, P < 0.001). The impact of depressive symp-
toms on cognition appears to be more limited, appearing
only in a trend manner (P < 0.10) and only in sub-
jects with moderate depressive symptoms (AOR = 1.716, 95
CI = 0.919-3.203, P = 0.09).
Anxiety. Anxiety, assessed by GAD, is significantly pre-
dictive only of a decrease in negative emotions at the
threshold ␣ = 0.05. This result is only for moderately anx-
ious subjects (AOR = 1.705, IC90 = 1.029-2.823, P = 0.038).
At the threshold ␣ = 0.10, the results suggest a tendency
for a smaller increase in positive sexual emotions in anxious
subjects, compared to subjects with no anxiety symptoms
(10 < GAD < 15: AOR = 0.586, 95 CI = 0.318-1.079, P = 0.086;
GAD > 15: AOR = 0.352, 95 CI = 0.122-1.017, P = 0.054).
Does COVID-19 pandemic affect sexual behaviour? A cross-sectional, crossnational online survey. S Y Arafat, A A Mohamed, S K Kar, P Sharma, R Kabir, Psychiatry Res. Article in pressArafat SY, Mohamed AA, Kar SK, Sharma P, Kabir R. Does COVID- 19 pandemic affect sexual behaviour? A cross-sectional, cross- national online survey. Psychiatry Res 2020 [Article in press].
The relation between mood and sexuality in heterosexual men. J Bancroft, E Janssen, D Strong, L Carnes, Z Vukadinovic, J S Long, Arch Sex Behav. 323Bancroft J, Janssen E, Strong D, Carnes L, Vukadinovic Z, Long JS. The relation between mood and sexuality in heterosexual men. Arch Sex Behav 2003;32(3):217-30.
Attachment styles among young adults: a test of a four-category model. K Bartholomew, L M Horowitz, J Pers Soc Psychol. 612226Bartholomew K, Horowitz LM. Attachment styles among young adults: a test of a four-category model. J Pers Soc Psychol 1991;61(2):226.
Global prevalence of anxiety disorders: a systematic review and meta-regression. A J Baxter, K M Scott, T Vos, H A Whiteford, Psychol Med. 435897Baxter AJ, Scott KM, Vos T, Whiteford HA. Global prevalence of anxi- ety disorders: a systematic review and meta-regression. Psychol Med 2013;43(5):897.
The sensitivity and specificity of the Major Depression Inventory, using the Present State Examination as the index of diagnostic validity. P Bech, N-A Rasmussen, L R Olsen, V Noerholm, W Abildgaard, J Affect Disord. 662-3Bech P, Rasmussen N-A, Olsen LR, Noerholm V, Abildgaard W. The sensitivity and specificity of the Major Depression Inventory, using the Present State Examination as the index of diagnostic validity. J Affect Disord 2001;66(2-3):159-64.
Psychometric evaluation of the Major Depression Inventory (MDI) as depression severity scale using the LEAD (Longitudinal Expert Assessment of All Data) as index of validity. P Bech, N Timmerby, K Martiny, M Lunde, S Søndergaard, BMC Psychiatry. 151190Bech P, Timmerby N, Martiny K, Lunde M, Søndergaard S. Psycho- metric evaluation of the Major Depression Inventory (MDI) as depression severity scale using the LEAD (Longitudinal Expert Assessment of All Data) as index of validity. BMC Psychiatry 2015;15(1):190.
When sex is more than just sex: attachment orientations, sexual experience, and relationship quality. G E Birnbaum, H T Reis, M Mikulincer, O Gillath, A Orpaz, J Pers Soc Psychol. 915929Birnbaum GE, Reis HT, Mikulincer M, Gillath O, Orpaz A. When sex is more than just sex: attachment orientations, sexual experience, and relationship quality. J Pers Soc Psychol 2006;91(5):929.
Stress and parenting during the global COVID-19 pandemic. S M Brown, J R Doom, S Lechuga-Peña, S E Watamura, T Koppels, Child Abuse Negl. 2020104699Article in pressBrown SM, Doom JR, Lechuga-Peña S, Watamura SE, Koppels T. Stress and parenting during the global COVID-19 pandemic. Child Abuse Negl 2020:104699 [Article in press].
The indirect impact of COVID-19 on women. T Burki, Lancet Infect Dis. 208Article in pressBurki T. The indirect impact of COVID-19 on women. Lancet Infect Dis 2020;20(8):904-5 [Article in press].
Sexual intrusive thoughts of college students. E S Byers, C Purdon, D A Clark, J Sex Res. 354Byers ES, Purdon C, Clark DA. Sexual intrusive thoughts of college students. J Sex Res 1998;35(4):359-69.
Le questionnaire sur les structures relationnelles : adaptation et validation de la version française du Experiences in Close Relationships -Relationship Structures Questionnaire. É Chaperon, S Dandeneau, Eur Rev Appl Psychol. 674Chaperon É, Dandeneau S. Le questionnaire sur les structures rela- tionnelles : adaptation et validation de la version française du Experiences in Close Relationships -Relationship Structures Questionnaire. Eur Rev Appl Psychol 2017;67(4):213-21.
Motivations for sex and risky sexual behavior among adolescents and young adults: a functional perspective. M L Cooper, C M Shapiro, A M Powers, J Pers Soc Psychol. 7561528Cooper ML, Shapiro CM, Powers AM. Motivations for sex and risky sexual behavior among adolescents and young adults: a func- tional perspective. J Pers Soc Psychol 1998;75(6):1528.
Best practices in exploratory factor analysis: Four recommendations for getting the most from your analysis. A B Costello, J W Osborne, Pract Assess Res Eval. 10Costello AB, Osborne JW. Best practices in exploratory factor anal- ysis: Four recommendations for getting the most from your analysis. Pract Assess Res Eval 2005;10:173-8.
Period poverty in a pandemic: harnessing law to achieve menstrual equity. B J Crawford, E G Waldman, file:/localhost/opt/grobid/grobid-home/tmp/dx.doi.org/10.1016/j.psychres.2020.113050Wash Univ Law Rev Forthcom. 2020Crawford BJ, Waldman EG. Period poverty in a pandemic: harnessing law to achieve menstrual equity. Wash Univ Law Rev Forth- com 2020., http://dx.doi.org/10.1016/j.psychres.2020.113050, Available at SSRN: https://ssrn.com/abstract=3692802.
Different perspectives on the sex-attachment link: towards an emotion-motivational account. M Dewitte, J Sex Res. 492-3Dewitte M. Different perspectives on the sex-attachment link: towards an emotion-motivational account. J Sex Res 2012;49(2-3):105-24.
Making love in the time of corona -considering relationships in lockdown. M Dewitte, C Otten, L Walker, Nat Rev Urol. 17Dewitte M, Otten C, Walker L. Making love in the time of corona -considering relationships in lockdown. Nat Rev Urol 2020;17:547-53.
How is the COVID-19 pandemic affecting our sexualities? An overview of the current media narratives and research hypotheses. N Doring, Arch Sex Behav. 2020Article in pressDoring N. How is the COVID-19 pandemic affecting our sexuali- ties? An overview of the current media narratives and research hypotheses. Arch Sex Behav 2020:2765-8 [Article in press].
Are online sexual activities and sexting good for adults' sexual well-being? Results from a national online survey. N Doring, M R Mohseni, Int J Sex Health. 303Doring N, Mohseni MR. Are online sexual activities and sexting good for adults' sexual well-being? Results from a national online sur- vey. Int J Sex Health 2018;30(3):250-63.
Robust but plastic: gender differences in emotional responses to sexual debut. Else-Quest Nm, J Sex Res. 514Else-Quest NM. Robust but plastic: gender differences in emotional responses to sexual debut. J Sex Res 2014;51(4):473-6.
Sex on the brain? An examination of frequency of sexual cognitions as a function of gender, erotophilia, and social desirability. T D Fisher, Z T Moore, M-J Pittenger, J Sex Res. 491Fisher TD, Moore ZT, Pittenger M-J. Sex on the brain? An examina- tion of frequency of sexual cognitions as a function of gender, erotophilia, and social desirability. J Sex Res 2012;49(1):69-77.
Sexual satisfaction and the importance of sexual health to quality of life throughout the life course of US adults. K E Flynn, L Lin, D W Bruner, J M Cyranowski, E A Hahn, D D Jeffery, J Sex Med. 1311Flynn KE, Lin L, Bruner DW, Cyranowski JM, Hahn EA, Jeffery DD, et al. Sexual satisfaction and the importance of sexual health to quality of life throughout the life course of US adults. J Sex Med 2016;13(11):1642-50.
Prévalence de la dépression majeure en France en population générale et en populations spécifiques de 2000 à 2018 : une revue systématique de la littérature. G Fond, C Lancon, P Auquier, L Boyer, Presse Med. 484Fond G, Lancon C, Auquier P, Boyer L. Prévalence de la dépression majeure en France en population générale et en populations spécifiques de 2000 à 2018 : une revue systématique de la lit- térature. Presse Med 2019;48(4):365-75.
Why pleasure matters: its global relevance for sexual health, sexual rights and wellbeing. J V Ford, Corona Vargas, E Finotelli, I FortenberryJr, J D Kismödi, E Philpott, A , Int J Sex Health. 313Ford JV, Corona Vargas E, Finotelli I Jr, Fortenberry JD, Kismödi E, Philpott A, et al. Why pleasure matters: its global relevance for sexual health, sexual rights and wellbeing. Int J Sex Health 2019;31(3):217-30.
The experiences in close relationships -Relationship Structures Questionnaire: a method for assessing attachment orientations across relationships. R C Fraley, M E Heffernan, A M Vicary, C C Brumbaugh, Psychol Assess. 233615Fraley RC, Heffernan ME, Vicary AM, Brumbaugh CC. The experiences in close relationships -Relationship Structures Questionnaire: a method for assessing attachment orientations across relationships. Psychol Assess 2011;23(3):615.
The role of positive emotions in positive psychology: the broaden-and-build theory of positive emotions. B L Fredrickson, Am Psychol. 563218Fredrickson BL. The role of positive emotions in positive psychology: the broaden-and-build theory of positive emotions. Am Psychol 2001;56(3):218.
Motivations sexuelles et attachement : étude exploratoire dans une population de 143 étudiantes francophones. B Gouvernet, S Combaluzier, P Chapillon, A Rezrazi, Sexologies. 244Gouvernet B, Combaluzier S, Chapillon P, Rezrazi A. Motiva- tions sexuelles et attachement : étude exploratoire dans une population de 143 étudiantes francophones. Sexologies 2015;24(4):194-201.
Effects of COVID-19 lockdown on mental health and sleep disturbances in. M R Gualano, G Lo Moro, G Voglino, F Bert, R Siliquini, Gualano MR, Lo Moro G, Voglino G, Bert F, Siliquini R. Effects of COVID-19 lockdown on mental health and sleep disturbances in
. Italy, Int J Environ Res Public Health. 17134779Article in pressItaly. Int J Environ Res Public Health 2020;17(13):4779 [Article in press].
A mixed-method study of individual, couple, and parental functioning during the state-regulated COVID-19 lockdown in Spain. C Günther-Bel, A Vilaregut, E Carratala, S Torras-Garat, C Pérez-Testor, Fam Process. 593Article in pressGünther-Bel C, Vilaregut A, Carratala E, Torras-Garat S, Pérez- Testor C. A mixed-method study of individual, couple, and parental functioning during the state-regulated COVID-19 lock- down in Spain. Fam Process 2020;59(3):1060-79 [Article in press].
Challenges in the practice of sexual medicine in the time of COVID-19 in the United Kingdom. L Jacob, L Smith, L Butler, Y Barnett, I Grabovac, D Mcdermott, J Sex Med. 177Jacob L, Smith L, Butler L, Barnett Y, Grabovac I, McDermott D, et al. Challenges in the practice of sexual medicine in the time of COVID-19 in the United Kingdom. J Sex Med 2020;17(7):1229-36.
Psychometric properties of the GAD-7 in a heterogeneous psychiatric sample. S U Johnson, P G Ulvenes, T Øktedalen, A Hoffart, Front Psychol. 101713Johnson SU, Ulvenes PG, Øktedalen T, Hoffart A. Psychometric prop- erties of the GAD-7 in a heterogeneous psychiatric sample. Front Psychol 2019;10:1713.
Les impacts du confinement lié au coronavirus sur la sexualité. S Landry, M Chartogne, A Landry, Sexologies. 29Landry S, Chartogne M, Landry A. Les impacts du confinement lié au coronavirus sur la sexualité. Sexologies 2020;29:173-80.
Less sex, but more sexual diversity: changes in sexual behavior during the COVID-19 coronavirus pandemic. J J Lehmiller, J R Garcia, A N Gesselman, K P Mark, file:/localhost/opt/grobid/grobid-home/tmp/dx.doi.org/10.1080/01490400.2020.1774016Leis Sci. 2020Article in pressLehmiller JJ, Garcia JR, Gesselman AN, Mark KP. Less sex, but more sexual diversity: changes in sexual behavior dur- ing the COVID-19 coronavirus pandemic. Leis Sci 2020:1-10, http://dx.doi.org/10.1080/01490400.2020.1774016 [Article in press].
Impact of the COVID-19 pandemic on partner relationships and sexual and reproductive health: cross-sectional, online survey study. G Li, D Tang, B Song, C Wang, S Qunshan, C Xu, J Med Internet Res. 22820961Article in pressLi G, Tang D, Song B, Wang C, Qunshan S, Xu C, et al. Impact of the COVID-19 pandemic on partner relationships and sexual and reproductive health: cross-sectional, online survey study. J Med Internet Res 2020;22(8):e20961 [Article in press].
Prevalence of depression in the community from 30 countries between 1994 and. G Y Lim, W W Tam, Y Lu, C S Ho, M W Zhang, R C Ho, Sci Rep. 81Lim GY, Tam WW, Lu Y, Ho CS, Zhang MW, Ho RC. Prevalence of depression in the community from 30 countries between 1994 and 2014. Sci Rep 2018;8(1):1-10.
COVID-19 and sexuality: reinventing intimacy. G P Lopes, Fbc Vale, I Vieira, A L Da Silva Filho, C Abuhid, S Geber, Arch Sex Behav. 49Lopes GP, Vale FBC, Vieira I, da Silva Filho AL, Abuhid C, Geber S. COVID-19 and sexuality: reinventing intimacy. Arch Sex Behav 2020;49:2735-8.
Romantic relationship conflict due to the COVID-19 pandemic and changes in intimate and sexual behaviors in a nationally representative sample of American adults. M Luetke, D Hensel, D Herbenick, M Rosenberg, J Sex Marital Ther. 46Luetke M, Hensel D, Herbenick D, Rosenberg M. Romantic rela- tionship conflict due to the COVID-19 pandemic and changes in intimate and sexual behaviors in a nationally representative sample of American adults. J Sex Marital Ther 2020;46:747-62.
Why humans have sex. C M Meston, D M Buss, Arch Sex Behav. 364Meston CM, Buss DM. Why humans have sex. Arch Sex Behav 2007;36(4):477-507.
Pornography use in the setting of the COVID-19 pandemic. G Mestre-Bach, G R Blycker, M N Potenza, J Behav Addict. 9Mestre-Bach G, Blycker GR, Potenza MN. Pornography use in the setting of the COVID-19 pandemic. J Behav Addict 2020;9:181-3.
Rapid detection of generalized anxiety disorder and major depression in epilepsy: validation of the GAD-7 as a complementary tool to the NDDI-E in a French sample. J-A Micoulaud-Franchi, S Lagarde, G Barkate, B Dufournet, C Besancon, Trébuchon-Da Fonseca, A , Epilepsy Behav. 57Micoulaud-Franchi J-A, Lagarde S, Barkate G, Dufournet B, Besancon C, Trébuchon-Da Fonseca A, et al. Rapid detection of generalized anxiety disorder and major depression in epilepsy: validation of the GAD-7 as a complementary tool to the NDDI-E in a French sample. Epilepsy Behav 2016;57:211-6.
Attachment in adulthood: structure, dynamics and change. M Mikulincer, P R Shaver, Guilford PressNew YorkThird EdMikulincer M, Shaver PR. Attachment in adulthood: structure, dynamics and change. Third Ed. New York: Guilford Press; 2016.
Implications of the COVID-19 pandemic for gender equity issues at work. F J Milliken, M K Kneeland, E Flynn, J Manag Stud. 57Milliken FJ, Kneeland MK, Flynn E. Implications of the COVID- 19 pandemic for gender equity issues at work. J Manag Stud 2020;57:1767-72.
The impact of the COVID-19 pandemic in the precipitation of intimate partner violence. D N Moreira, M P Da Costa, Int J Law Psychiatry. 71101606Article in pressMoreira DN, da Costa MP. The impact of the COVID-19 pandemic in the precipitation of intimate partner violence. Int J Law Psychi- atry 2020;71:101606 [Article in press].
Content and valence of sexual cognitions and their relationship with sexual functioning in Spanish men and women. N Moyano, E S Byers, J C Sierra, Arch Sex Behav. 458Moyano N, Byers ES, Sierra JC. Content and valence of sexual cog- nitions and their relationship with sexual functioning in Spanish men and women. Arch Sex Behav 2016;45(8):2069-80.
Sexual modes questionnaire: Measure to assess the interaction among cognitions, emotions, and sexual response. P J Nobre, J Pinto-Gouveia, J Sex Res. 404Nobre PJ, Pinto-Gouveia J. Sexual modes questionnaire: Measure to assess the interaction among cognitions, emotions, and sexual response. J Sex Res 2003;40(4):368-82.
Cognitions, emotions, and sexual response: analysis of the relationship among automatic thoughts, emotional responses, and sexual arousal. P J Nobre, J Pinto-Gouveia, Arch Sex Behav. 374Nobre PJ, Pinto-Gouveia J. Cognitions, emotions, and sex- ual response: analysis of the relationship among automatic thoughts, emotional responses, and sexual arousal. Arch Sex Behav 2008;37(4):652-61.
Changes in sexuality and quality of couple relationship during the COVID-19 lockdown. M Panzeri, R Ferrucci, A Cozza, L Fontanesi, file:/localhost/opt/grobid/grobid-home/tmp/dx.doi.org/10.3389/fpsyg.2020.565823Front Psychol. Article in pressPanzeri M, Ferrucci R, Cozza A, Fontanesi L. Changes in sexuality and quality of couple relationship dur- ing the COVID-19 lockdown. Front Psychol 2020., http://dx.doi.org/10.3389/fpsyg.2020.565823 [Article in press].
Sexual self-esteem, sexual functioning and sexual satisfaction in Portuguese heterosexual university students. M M Peixoto, I Amarelo-Pires, Pimentel Biscaia, M S Machado, P P , Psychol Sex. 94Peixoto MM, Amarelo-Pires I, Pimentel Biscaia MS, Machado PP. Sexual self-esteem, sexual functioning and sexual satisfaction in Portuguese heterosexual university students. Psychol Sex 2018;9(4):305-16.
Mental health before and during the COVID-19 pandemic: a longitudinal probability sample survey of the UK population. M Pierce, H Hope, T Ford, S Hatch, M Hotopf, A John, Lancet Psychiatry. 7Pierce M, Hope H, Ford T, Hatch S, Hotopf M, John A, et al. Mental health before and during the COVID-19 pandemic: a longitu- dinal probability sample survey of the UK population. Lancet Psychiatry 2020;7:883-91.
Exploring the frequency, diversity, and content of university students' positive and negative sexual cognitions. C A Renaud, E S Byers, Can J Hum Sex. 8117Renaud CA, Byers ES. Exploring the frequency, diversity, and content of university students' positive and negative sexual cognitions. Can J Hum Sex 1999;8(1):17.
Prevalence of stress, anxiety, depression among the general population during the COVID-19 pandemic: a systematic review and meta-analysis. N Salari, A Hosseinian-Far, R Jalali, A Vaisi-Raygani, S Rasoulpoor, M Mohammadi, Glob Health. 161Article in pressSalari N, Hosseinian-Far A, Jalali R, Vaisi-Raygani A, Rasoulpoor S, Mohammadi M, et al. Prevalence of stress, anxiety, depression among the general population during the COVID-19 pan- demic: a systematic review and meta-analysis. Glob Health 2020;16(1):1-11 [Article in press].
A systematic review of sexual satisfaction. M Sánchez-Fuentes, M Santos-Iglesias, P Sierra, J C , Int J Clin Health Psychol. 141Sánchez-Fuentes M, del M, Santos-Iglesias P, Sierra JC. A system- atic review of sexual satisfaction. Int J Clin Health Psychol 2014;14(1):67-75.
A brief measure for assessing generalized anxiety disorder: the GAD-7. R L Spitzer, K Kroenke, J B Williams, B Löwe, Arch Intern Med. 16610Spitzer RL, Kroenke K, Williams JB, Löwe B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med 2006;166(10):1092-7.
Evidence of change in men's versus women's emotional reactions to first sexual intercourse: a 23-year study in a human sexuality course at a Midwestern university. S Sprecher, J Sex Res. 514Sprecher S. Evidence of change in men's versus women's emo- tional reactions to first sexual intercourse: a 23-year study in a human sexuality course at a Midwestern university. J Sex Res 2014;51(4):466-72.
Sex in the time of COVID-19: results of an online survey of gay, bisexual and other men who have sex with men's experience of sex and HIV prevention during the US COVID-19 epidemic. R Stephenson, T M Chavanduka, M T Rosso, S P Sullivan, R A Pitter, A S Hunter, 10.1007/s10461-020-03024-8AIDS Behav. Stephenson R, Chavanduka TM, Rosso MT, Sullivan SP, Pitter RA, Hunter AS, et al. Sex in the time of COVID-19: results of an online survey of gay, bisexual and other men who have sex with men's experience of sex and HIV preven- tion during the US COVID-19 epidemic. AIDS Behav 2020., http://dx.doi.org/10.1007/s10461-020-03024-8.
The role of cognitive processing factors in sexual function and dysfunction in women and men: a systematic review. I M Tavares, C V Moura, P J Nobre, file:/localhost/opt/grobid/grobid-home/tmp/dx.doi.org/10.1007/s10461-020-03024-8Sex Med Rev. 8Tavares IM, Moura CV, Nobre PJ. The role of cognitive processing factors in sexual function and dysfunction in women and men: a systematic review. Sex Med Rev 2020;8:403-30.
Un Women, Policy brief: the Impact of COVID-19 on women. 2020UN Women. Policy brief: the Impact of COVID-19 on women (9th April, 2020); 2020 [Accessed on 9th May 2020. Available from: https://www.un.org/sexualviolenceinconflict/wp-content/ uploads/2020/06/report/policy-brief-the-impact-of-covid-19- on-women/policy-brief-the-impact-of-covid-19-on-women-en- 1.pdf].
A warm nest or ''the talk''? Exploring and explaining relations between general and sexuality-specific parenting and adolescent sexual emotions. M Verbeek, D Van De Bongardt, E Reitz, M Deković, J Adolesc Health. 662Article in pressVerbeek M, Van De Bongardt D, Reitz E, Deković M. A warm nest or ''the talk''? Exploring and explaining relations between general and sexuality-specific parenting and adolescent sexual emo- tions. J Adolesc Health 2020;66(2):210-6 [Article in press].
Defining sexual health: report of a technical consultation on sexual health. World Health OrganizationGeneva. Geneva, SwitzerlandWHOWHO. Defining sexual health: report of a technical consultation on sexual health, 28-31 January 2002, Geneva. Geneva, Switzer- land: World Health Organization (WHO); 2006.
What love has to do with it: an attachment perspective on pair bonding and sexual behavior. V Zayas, D Ram, Behav Brain Sci. 321Zayas V, Ram D. What love has to do with it: an attachment per- spective on pair bonding and sexual behavior. Behav Brain Sci 2009;32(1):44-5.
| [
-0.06976982951164246,
0.018801262602210045,
-0.058965638279914856,
0.08930094540119171,
-0.010476031340658665,
0.17725330591201782,
-0.013604698702692986,
0.156667560338974,
0.15362559258937836,
0.07436412572860718,
0.03074733354151249,
-0.04069416597485542,
-0.05214405432343483,
0.0630824... |
arXiv:1407.5052v2 [hep-ex] 30 Jul 2014 CL s Method at Gaussian Limit to Present Searches
X Qian
Brookhaven National Laboratory
UptonNY
A Tan
Department of Statistics and Actuarial Science
University of Iowa
Iowa CityIA
J J Ling
Department of Physics
University of Illinois of Urbana-Champaign
UrbanaIL
Y Nakajima
Lawrence Berkeley National Laboratory
BerkeleyCA
C Zhang
Brookhaven National Laboratory
UptonNY
arXiv:1407.5052v2 [hep-ex] 30 Jul 2014 CL s Method at Gaussian Limit to Present Searches
(Dated: July 31, 2014)
We describe a new method based on the CLs approach [1] to present results in searches of new physics under the condition that the relevant nuisance parameter space is continuous. Essentially, this method uses a Gaussian approximation for the distribution of a log-likelihood ratio test statistic used in a two-hypotheses testing problem, when the sample size is large. It leads to a simple way to form exclusion sets for the parameters of interest. This Gaussian CLs method can be seen as an alternative to the traditional method of setting confidence intervals based on p-values. And one advantage of the Gaussian CLs method is that, it requires a simple procedure that is applicable in many situations where the p-value method requires computationally-intensive Monte Carlo instead of a popular thresholding rule based on a Chi-square distribution. We illustrate this method in a problem of searching for a sterile neutrino. Specifically, we derive exclusion sets in the two-dimensional parameter space of (sin 2 2θ, |∆m 2 |) based on the Gaussian approximation, and demonstrate that it provides adequately accurate results. Finally, we discuss the advantages and disadvantages of our method in comparison to the traditional methods of setting confidence intervals. * Corresponding author: xqian@bnl.gov † Corresponding author: aixin-tan@uiowa.edu 1 Other examples include dark matter searches (the interaction cross section vs. the mass of the dark matter particle) and SUSY (super symmetry) particle searches at LHC (the interaction coupling vs. the mass scale).
I. INTRODUCTION
The Standard Model of the particle physics has been extremely successful since its establishment in mid-1970s. In particular, the Higgs-like particle discovered at LHC in 2012 [2,3] might complete the list of fundamental particles predicted by the minimal Standard Model. Nevertheless, there is a lot of experimental evidence that points to new physics beyond the Standard Model: neutrino oscillations indicate non-zero neutrino mass; various gravitational effects indicate the existence of non-baryonic dark matter; the accelerating expansion of our universe indicates the existence of dark energy; the large observed matter-anti-matter asymmetry indicates the existence of additional CP violation source beyond that in the quark mixing matrix, etc. Searches for new physics beyond the Standard Model have been and still are at the frontier of high energy particle physics.
In many occasions, search results are presented in terms of constraints in a continuous parameter space. One example is the sterile neutrino suggested by LSND [4], MiniBooNE [5], and reactor antineutrino anomalies [6]. 1 In this case, results are generally shown in the two-dimensional phase space of (sin 2 2θ, |∆m 2 |), where θ is the mixing angle involving the sterile neutrino, and |∆m 2 | is mass-squared difference involving neutrino beyond three generations. Mathematically, the problem of searching for new physics is transformed into a problem of parameter estimation, such as estimating sin 2 2θ and |∆m 2 | in the aforementioned example. Right now, for such problems, one of the most popular statistical methods is to present a set of plausible values of the parameters in a continuous space, called a confidence interval (CI). The construction of CIs is usually based on a test statistic that takes the form of ∆χ 2 (β) := χ 2 (β) − χ 2 min , where β denotes the vector of parameters of interest, such as β = (sin 2 2θ, |∆m 2 |). Then any given value of β is included in the CI if its corresponding ∆χ 2 (β) is below a threshold based on a Chi-square distribution with appropriate degrees of freedom. A summary of this Chi-square method can be found in the review of particle physics by the particle data group [7], and a detailed example of such a test statistic is provided in Sec. II.
In this paper, we consider a popular alternative to the aforementioned construction of CIs in searching for new physics. The approach we consider is the CL s approach [1,8]. Our new contribution is to propose and validate an approximation method to carry out the CL s approach that is computationally efficient and applicable in very general setups.
Recall the CI approach assigns parameter values β to a confidence interval based on first calculating its corresponding test statistic ∆χ 2 (β) and then obtaining its corresponding p-value. In comparison, the CL s approach puts β values into an exclusion set by first calculating a test statistic ∆T (β 0 , β), which is usually some variation of the negative-two-log-likelihood ratio between a reference value, β 0 , and the value being inspected, β, and then obtaining its corresponding CL s value, which is the ratio between the two p-values under β 0 and β, respectively. Here, the CL s value serves as a measure of the plausibility of β. We will show that, under regularity conditions that are much milder than that required by the Chi-square method, one can easily calculate CL s val-ues using a Gaussian approximation to the distribution of ∆T (β 0 , β) at large data limit [9,10], hence avoid using the expensive MC method in setting exclusion sets. We will refer to this method as the Gaussian CL s method. Another benefit brought by the Gaussian CL s method is, it allows easy combination of exclusions from different experiments, given they are not correlated.
Here, we briefly compare the Gaussian CL s method to the traditional method of constructing CIs based on ∆χ 2 (β) (Chi-square CI method). The mathematical reasoning behind the Chi-square CI method is the Wilks' theorem [11], which states that ∆χ 2 (β) with β being the true value follows approximately a Chi-square distribution under certain regularity conditions to be elaborated in details in Sec. II. Therefore, one can set approximate CIs based on ∆χ 2 (β) and threshold it by quantiles of a Chi-square distribution. In analogy, under another set of regularity conditions to be elaborated in details in Sec. III A, the Gaussian CL s method utilizes the approximate Gaussian distribution of the log-likelihood ratio ∆T (β 0 , β), which simplifies the calculation of CL s values in setting exclusion sets. We emphasize that, the set of regularity conditions required by the Gaussian CL s method is much more easily satisfied than that of the Wilks' theorem. There are many cases in the search for new physics when both sets of regularity conditions hold, then the Gaussian CL s method and the Chi-square CI method can both be used and provide complementary analysis. There are also many cases where the Gaussian CL s method is applicable but the Chi-square CI method is not. This is one of the main advantages of our proposed Gaussian CL s method.
When some of the regularity conditions of the Wilks' theorem break down, a well known method to setting CIs is the Feldman-Cousins method [12], which approximates the distribution of ∆χ 2 (β) as accurately as desired using Monte Carlo (MC) samples. Despite the theoretical property that a large enough Monte Carlo sample size guarantees the validity of the resulting CIs, the Feldman-Cousins method can be computationally intensive and time consuming. Furthermore, unlike the popular Chisquare method, combining results from different experiments by strictly following the Feldman-Cousins method requires fitting the combined data from all those experiments, which makes it even more computationally intensive. (There are known examples of combining CIs, but they all require some forms of approximation to the Feldman-Cousins' method.) In contrast, we will show that in many of these situations when it is difficult to set valid CIs, the Gaussian CL s method can easily be used to set exclusion sets, as well as to combine exclusion sets from different experiments, and neither task requires intensive computation. This is particularly attractive in the application of searching for new physics. This paper is organized as the following. In Sec. II, we briefly review the Chi-square CI method. We also describe the Feldman-Cousins method, which is commonly used when the Chi-square CI method is not applicable. In Sec. III, we describe the Gaussian CL s method. Specifically, we present a mathematical proof that shows, when the data size increases, the distribution of the loglikelihood ratio statistic ∆T (β 0 , β), which we can simply write as ∆T when β 0 and β are fixed, approaches the Gaussian distribution with mean ∆T and standard deviation 2 |∆T |. The mathematical definition of ∆T is given later in Eq. (13). Basically, it is the value of the statistic ∆T calculated using the Asimov data set [13]. The Asimov data set refers to the most probable data set given the current true model without any statistical fluctuations nor systematic variations. Through an example of searching for a sterile neutrino, we compare the Gaussian CL s method with the traditional CI method in Sec. IV. We further present the discussion and summary in Sec. V and Sec. VI, respectively.
II. CONFIDENCE INTERVALS
In this section, we briefly review the traditional method of setting confidence intervals in the context of neutrino oscillations. Consider a neutrino energy spectrum that consists of n energy bins. Assume that the expected number of counts in each bin is a function of the vector of parameters of main interest, β = (sin 2 2θ, |∆m 2 |), and a vector of nuisance parameters (such as the overall normalization), η. Let Θ, M , and H denote the parameter space of sin 2 2θ, |∆m 2 |, and η, respectively. There are two further physical constraints: sin 2 2θ ≥ 0 and |∆m 2 | ≥ 0. Then for the i-th bin, µ i (sin 2 2θ, |∆m 2 |, η) and N i represent the expected and the observed counts of neutrino induced reactions, respectively. When µ i is large enough, the distribution of N i can be well approximated by a Gaussian distribution with mean µ i and standard deviation √ µ i . Given any specific guess of the value of the parameters (sin 2 2θ, |∆m 2 |, η), once the data x = {N i , i = 1, . . . , n} is observed, one can calculate the deviation of the data from the expected values {µ i (sin 2 2θ, |∆m 2 |, η), i = 1, . . . , n} to measure the implausibility of the hypothesized parameter value. A few commonly used definition of deviations can be found later in Eq. (5), (6), (7), and (8). For instance, when certain knowledge concerning the nuisance parameter η (e.g. knowledge of detecting efficiency and neutrino flux) is available, one useful definition of deviation is given by
χ 2 (sin 2 2θ, |∆m 2 |, η) = χ 2 stat (sin 2 2θ, |∆m 2 |, η) + χ 2 p (η) = i (N i − µ i (sin 2 2θ, |∆m 2 |, η)) 2 (δN i ) 2 + (η − η 0 ) 2 (δη) 2 .(1)
Here, the general notation δw represents the standard deviation of a variable w. So δN i = √ µ i , and the corresponding χ 2 stat term is called Pearson Chi-square.
Based on the test statistic χ 2 (sin 2 2θ, |∆m 2 |, η) in Eq. (1), confidence regions can be obtained for β = (sin 2 2θ, |∆m 2 |).
Specifically, we first define sin 2 2θ min and |∆m 2 min | to be the best fit to the data in the sense that (sin 2 2θ min , |∆m 2 min |, η min ) = arg min sin 2 2θ,|∆m 2 |,η χ 2 (sin 2 2θ, |∆m 2 |, η). Here, the minimum is taken over Θ × M × H. The general notation arg min w h(w) denotes the value of w that minimizes the given function h. Note that (sin 2 2θ min , |∆m 2 min |), won't be exactly the true value of the parameter (sin 2 2θ, |∆m 2 |), and a repetition of the experiment would yield a data set that corresponds to a different best guess. So instead of reporting only (sin 2 2θ min , |∆m 2 min |), it is more rational to report a set of plausible values of (sin 2 2θ, |∆m 2 |) that fit the observed data not too much worse than that of the best fit, and state how trustworthy the set is. Indeed, for any given (sin 2 2θ, |∆m 2 |), let η min (sin 2 2θ, |∆m 2 |) = arg min η χ 2 (sin 2 2θ, |∆m 2 |, η), and define
∆χ 2 min (sin 2 2θ, |∆m 2 |) ≡ χ 2 (sin 2 2θ, |∆m 2 |, η min (sin 2 2θ, |∆m 2 |)) − χ 2 (sin 2 2θ min , |∆m 2 min |, η min ),(2)
then a level a confidence interval based on Eq. (2) is defined to be
C a = {(sin 2 2θ, |∆m 2 |) ∈ Θ × M : ∆χ 2 min ≤ t a } ,(3)
where we use the standard set-builder notation {h(w) : restriction w} to denote a set that is made up of all the points h(w) such that w satisfies the restriction to the right of the colon. The key in constructing Eq. (3) is to specify the correct threshold value t a for a given confidence level a. Most commonly examined confidence levels use a = 68.3% (1σ), 95.5% (2σ), 99.7% (3σ), which are linked to threshold values t a = 2.31, 5.99, 11.8, respectively [7]. Note that these three values are the 68.3%, 95.5% and 99.7% quantiles of the Chi-square distribution with two degrees of freedom, respectively. The reason why these threshold values are used is that, C a is indeed constructed upon screening the entire parameter place by inspecting one point at a time, denoted by (sin 2 2θ 0 , |∆m 2 0 |), and testing the pair of hypotheses, H 0 : (sin 2 2θ, |∆m 2 |) = (sin 2 2θ 0 , |∆m 2 0 |) versus H a : otherwise. For this test using the Chi-square statistic ∆χ 2 min (sin 2 2θ 0 , |∆m 2 0 |), the full parameter space is Ω = (sin 2 2θ, |∆m 2 |, η) ∈ Θ×M ×H and the null hypothesis space is Ω 0 = {(sin 2 2θ 0 , |∆m 2 0 |)} × H. According to the Wilks' theorem [11], if certain regularity conditions hold, mainly 1. the parameter space Θ × M × H is a continuous space, and the the model likelihood function is a smooth function (for example three times differentiable) in the parameters, 2. Ω contains an open neighborhood of the true value (sin 2 2θ 0 , |∆m 2 0 |, η 0 ), and 3. the data size N i is large for each i = 1, . . . , n, then the statistic ∆χ 2 min (sin 2 2θ 0 , |∆m 2 0 |) follows approximately a Chi-square distribution when H 0 is true. Further, the degree of freedom of this Chi-square distribution equals the difference between the dimension of Ω and that of Ω 0 , namely 2, in the current case. This procedure of constructing confidence intervals and its extensions have been successfully applied in many studies in order to constrain various parameters in the neutrino physics. One recent example is the first measurement of ∆m 2 ee and the precision measurement of sin 2 2θ 13 from the Daya Bay collaboration [14].
Although this method, referred to as the Chi-square CI method, has been widely used in analyzing experimental data, it does not always produce confidence interval that has the correct coverage probability. Its limitations have been addressed by, for example, Feldman and Cousins [12]. One example is the searches for neutrino oscillations in the disappearance mode. The oscillation probability with (sin 2 2θ, |∆m 2 |) in a 2-flavor framework is written as:
P i = 1 − sin 2 2θ · sin 2 (1.27 · |∆m 2 | · L/E ν i ),(4)
where L and E ν i are the distance neutrino travels and the neutrino energy at the i-th bin, respectively. Then the expected bin counts µ i = E(N i ) are such that µ i ≈ a i · P i + b i , where a i and b i are coefficients that may depend on the nuisance parameters η.
The reason why the Chi-square method fails for the above neutrino oscillations example is the following. A key middle step in the proof of the Wilks' theorem is that conditions 1∼3 above together ensure that the MLE (maximum likelihood estimator) of (sin 2 2θ, |∆m 2 |) has a sampling distribution close to that of a Gaussian distribution. This suggests two things. (1) When testing H 0 of the form: (sin 2 2θ, |∆m 2 |) = (0, |∆m 2 0 |), condition 2 is violated, and hence the Wilks' theorem does not apply no matter how large the data size is. (2) On the other hand, for testing H 0 of all other forms, conditions 1 and 2 are both satisfied, hence as the sample size grows to infinity, the sampling distribution of ∆χ 2 min (sin 2 2θ 0 , |∆m 2 0 |) will eventually converge to a Chi-square distribution. However, for instance if the true value sin 2 2θ 0 is close to 0, then there could be a non-ignorable probability that we observe a data set that results in a MLE of sin 2 2θ equaling to 0. This clearly prevents the sampling distribution of the MLE of (sin 2 2θ, |∆m 2 |) from being closely approximated by a Gaussian distribution. Indeed, the closer sin 2 2θ 0 (or |∆m 2 0 |) is to 0, the larger the data size is needed to overcome the above phenomena. To say this in another way, given any fixed large data size, there is always a small neighborhood of zero, say B 0 , such that if we test an H 0 of the form (sin 2 2θ, |∆m 2 |) = (sin 2 2θ 0 , |∆m 2 0 |) where either sin 2 2θ 0 ∈ B 0 or |∆m 2 0 | ∈ B 0 , then the resulting test statistic ∆χ 2 min (sin 2 2θ 0 , |∆m 2 0 |) will not follow a distribution that can be adequately approximated by the Chi-square distribution.
The latter point can also be understood intuitively. Although the parameter space of sin 2 2θ vs. |∆m 2 | is usually displayed as Fig. 1a and is flat, the effective phase space of (sin 2 θ, |∆m 2 |) measured by χ 2 defined in Eq. (1) is no longer flat (Fig. 1b). Due to the functional form of the oscillation formula, the effective phase space becomes more compact at smaller sin 2 2θ, as differences between spectra with different values of |∆m 2 | become smaller. Therefore, more data is needed to reach the large data limit required by the Wilks' theorem. For sin 2 2θ true = 0, the effective phase space only contains a single point, since |∆m 2 | will have no impact on the neutrino spectrum. It is therefore impossible to reach the large data limit. Even for non-zero values of sin 2 2θ true , the required data could be well beyond the experimental reach.
When these regularity conditions are not satisfied, one can use the Feldman-Cousins method [12] to set confidence intervals. Below, we review how to produce a valid 1-σ (68%) confidence interval of (sin 2 2θ, |∆m 2 |) using MC. This method can be easily generalized to build confidence intervals of any level.
Having observed data x = {N 1 , · · · , N n }, apply the following procedure to every (sin 2 2θ, |∆m 2 |) in the parameter space Θ × M (fix one pair of (sin 2 2θ, |∆m 2 |) at a time):
1. Calculate ∆χ 2 min (sin 2 2θ, |∆m 2 |) x with Eq. (2) based on the observed data.
Simulate a large number of MC samples, say
{x (j) } T j=1 , where x (j) = {N (j) 1 , · · · , N (j)
n } is generated from the model with true parameter value (sin 2 2θ, |∆m 2 |). For j = 1, . . . , T , calculate ∆χ 2 min (sin 2 2θ, |∆m 2 |) (j) , that is Eq. (2) based on the j-th MC sample x (j) . This produces an empirical distribution of the statistic ∆χ 2 min (sin 2 2θ, |∆m 2 |). 3. Calculate the percentage of MC samples such that ∆χ 2 min (sin 2 2θ,
|∆m 2 |) (j) < ∆χ 2 min (sin 2 2θ, |∆m 2 |) x .
Then (sin 2 2θ, |∆m 2 |) is included in the 1-σ confidence interval if and only if the percentage is smaller than 68%.
The key of the above procedure is to generate an empirical distribution of ∆χ 2 min (sin 2 2θ, |∆m 2 |), as it no longer follows a Chi-square distribution.
Feldman-Cousins method guarantees the validity of the resulting CIs. However, the procedure can be very timeconsuming when the dimension of the vector of unknown parameters is high and/or when a fine grid of the phase space needs to be examined. In addition, the number of MC samples, T , needed in order to produce an empirical distribution that leads to an accurate enough CI, in-creases quickly as the required confidence level increases. The procedure could become inhibitively expensive if the minimization process used to find (sin 2 2θ min , |∆m 2 min |) is slow due to the existence of many nuisance parameters or other technical reasons. Furthermore, there is no simple recipe to strictly combine the CIs generated with the Feldman-Cousins method from different experiments to form an overall CI. To see this, consider a simple example where two experiments are carried out to probe the phase space of (sin 2 2θ, |∆m 2 |). For any phase space point (sin 2 2θ 0 , |∆m 2 0 |), each experiment yields its own statistic ∆χ 2 min = χ 2 (sin 2 2θ 0 , |∆m 2 0 |) − χ 2 min (sin 2 2θ min , |∆m 2 min |). However, the minimum phase space point, (sin 2 2θ min , |∆m 2 min |), based on the first experiment is typically different from that of the second experiment. Once the two experiments are combined, a strict implementation of the Feldman-Cousins' method requires the global minimum phase space point, which is in general unattainable from the experiment-wise minimum phase space points directly. Indeed, one has to redo Monte Carlo simulation under the setting of the combined data, which is extremely heavy computationally since minimization has to be done for each Monte Carlo sample.
In the next section, we introduce a new method to carry out the CL s approach, that is able to produce exclusion sets quickly in searching for new physics. Also, this method allows simple combination of results from different experiments to provide global analysis.
III. THE CLs APPROACH BASED ON THE ∆T STATISTIC AND ITS GAUSSIAN APPROXIMATION
A. The CLs Approach Based on the ∆T Statistic
The CL s approach [1,8] is a popular approach to present searches for new physics beyond the Standard Model. Recent examples of using this approach in neutrino physics can be found in Ref. [16,17]. The CL s approach is complementary to the traditional approach with confidence intervals: CL s is appropriate in setting exclusion limits, while the confidence interval is appropriate in treating established signals [1]. In this section, we will briefly review the principle of the CL s approach in a two-hypotheses testing problem.
Suppose a problem involves two hypotheses: the null hypothesis H 0 (typically the Standard Model) with predicted number of events µ(η) = (µ 1 (η), · · · , µ N (η)) and the alternative hypothesis H 1 (typically a new physics model) with predicted number of events ν(ζ) = (ν 1 (ζ), · · · , ν N (ζ)). Here, η and ζ represent the vectors of nuisance parameters under the two hypotheses respectively, and they could be of different dimension. We now introduce a test statistic, usually denoted by ∆T , for testing H 0 and H 1 . Note that there is more than one version of the definition of ∆T that we will list below. (color online) Illustration of the CLs approach with log-likelihood ratio ∆T . In order to be consistent with the convention in Ref. [15], we plot the densities of −∆T instead. The black curve represents the density when the null hypothesis is true, the red curve represents the density when the alternative hypothesis (new physics) is true, and the most probable value of the black curve (e.g. the peak) would be positioned to the left of the most probable value of the red curve. The green line is positioned at −∆T (x), where x is the observed data. Hence p0 is the probability of seeing potential observations that yield a −∆T value larger than −∆T (x). Similarly, 1 − p1 is the probability of seeing potential observations that lead to a −∆T value smaller than −∆T (x).
To lead to the definition of ∆T , we start with either the Poisson or the Normal distribution to model the data x, and use the general notation L(x, λ) to denote the corresponding likelihood, where λ equals to µ(η) under H 0 , and ν(ζ) under H 1 , respectively. Following the convention of Ref. [18], let
a(x) = 2 log L(x, λ = x), then define T H0 (x, η) = −2 log(L(x, µ(η))) + a(x), and T H1 (x, ζ) = −2 log(L(x, ν(ζ))) + a(x).
Take the Poisson model for example, we have
2 log L(x, λ) = n i=1 −2N i log λ i + 2λ i + 2 log(N i !) ≈ n i=1 [2(λ i − N i + N i log(N i /λ i )) + log N i ] + n log(2π),
and a(x) = n i=1 log N i + n log(2π). Then, looking at the definition of T H0 for instance, we have
T H0 (x, η) = n i=1 2 (µ i (η) − N i + N i log(N i /µ i (η))) .
In practice, when there are prior experiments carried out to study the nuisance parameter, an additional term that reflects deviation from this prior knowledge is added to the definition of T H0 (x, η). We denote this term by
χ 2 penalty (η), an example of which is the term (η−η0) 2 (δη) 2
in Eq. (1). And when the data size is large, terms of smaller order are sometimes omitted from the definition of T H0 (x, η). After all, there are at least four common variations for T H0 (x, η) used in practice:
T H0 (x, η) = n i=1 2 µ i − N i + N i log N i µ i + χ 2 penalty (η),(5)T H0 (x, η) = n i=1 log µ i N i + n i=1 (N i − µ i ) 2 µ i + χ 2 penalty (η),(6)T H0 (x, η) = n i=1 (N i − µ i ) 2 µ i + χ 2 penalty (η),(7)T H0 (x, η) = n i=1 (N i − µ i ) 2 N i + χ 2 penalty (η).(8)
Here, Eq. (5) and Eq. (6) origins from the likelihood function of the Poisson and the Gaussian distribution, respectively. Eq. (7) and Eq. (8) are variations of Eq. (6), and are commonly referred to as the Pearson and the Neyman Chi-square, respectively. Note that Eq. (1) is a specific example of Eq. (7). At large data limit, differences among the numerical values of T H0 (x, η) based on these four definitions are negligible. En route to form the test statistic ∆T , T H0 (x, η) is further minimized over all nuisance parameters (including unknown parameters and systematic uncertainties) to obtain T min H0 (x) = min η T H0 (x, η). Also, T min H1 (x, ζ) can be defined similarly for the alternative hypothesis H 1 . Then the test statistic
∆T (x) = T min H1 (x) − T min H0 (x)(9)
is constructed in order to evaluate whether the observed data x favors H 0 or H 1 . It is easy to see that a positive ∆T (x) would favor H 0 , and a negative ∆T (x) would favor H 1 . In addition, the absolute size of ∆T (x) reflects how much one hypothesis is favored relative to the other. (An alternative way to define ∆T (x) is to replace T min H0 (x) and T min H1 (x) by T mag H0 (x) and T mag H1 (x), respectively, which are the marginalized, or say integrated version of T H0 (x, η) and T H1 (x, η) over all nuisance parameters.) Fig. 2 is a heuristic illustration of the distribution of the log-likelihood ratio ∆T (X), where X stands for data generated from a potential repeat of the experiment. The black (red) curve stands for the density function of the distribution under the assumption that the null (alternative) hypothesis is true. The green line represents ∆T (x), the log-likelihood ratio calculated from the observed data x. The CL s value is then defined as:
CL s (x) = 1 − p 1 1 − p 0 ,(10)
where p 0 is the probability that a potential repeat of the experiment will yield a ∆T (X) value smaller than (to the right of) ∆T (x), had the null hypothesis been true. Similarly, 1 − p 1 is the probability that a potential repeat of the experiment leads to a ∆T (X) value larger than (to the left of) ∆T (x), had the alternative hypothesis been true. Given the definition of CL s in Eq. (10), one can see a CL s value close to zero would strongly favor the null hypothesis H 0 , while a CL s value close to one would generally favor the alternative hypothesis H 1 . 2 In such experiments, the null hypothesis is traditionally specified to be the Standard Model. And the standard exclusion region of the parameter space is usually defined as the set of parameter values of new physics that corresponds to CL s smaller than 0.05 [15]. Of course, other threshold values of the CL s can be used to set exclusion regions.
The CL s value defined in Eq. (10) is essentially a ratio of two p-values. Compared with the popular (singlesided) p-value, CL s has clear advantages in situations where the null hypothesis H 0 and the alternative hypothesis H 1 are very similar (see Fig. 3). For example, assume the data x is an "extreme" measurement with respect to the alternative hypothesis H 1 (e.g. small p 1 ), it will also be disfavored by the null hypothesis H 0 (e.g. small p 0 ). If only a single p-value, either p 0 or p 1 , is examined as in the CI approach, then one would draw the inappropriate conclusion of excluding H 0 or H 1 and favor the other hypothesis. However, in reality, since the hypotheses H 0 and H 1 are similar, the data does not really carry enough power to differentiate them. The CL s value that is the ratio of 1 − p 1 and 1 − p 0 will protect against this kind of situations.
Given the observed ∆T (x), to obtain the value of p 0 and p 1 required to calculate the CL s , one needs to find the parent distribution of ∆T (X) under the null and the alternative hypothesis, respectively. While Monte Carlo simulations will always provide a valid approximation of the parent distributions of ∆T (X), simpler approximation methods are desired to lower the burden of computation. We show in the Sec. III C that, under the following set of conditions, 1. the parameter space (H) of the nuisance parameters η and ζ are both continuous and the the model likelihood function is a smooth function (for example three times differentiable) in the parameters, 2. the data size N i is large for each i = 1, . . . , n,
3. the best model under the null hypothesis H 0 and the alternative hypothesis H 1 are relatively close, in the sense that |µ 0 i − ν 0 i | << µ 0 i ∼ ν 0 i , for i = 1, . . . , n, a simple approximation for the parent distribution of ∆T (X) under H j , for either j = 0 or 1, is the Gaussian distribution with mean ∆T Hj and standard deviations 2 |∆T Hj |. We emphasize that, compared to the first regularity condition required by the Wilks' theorem, our first regularity condition is much easier to achieve. Because we require continuity only for the parameter space H instead of for the parameter space Θ × M × H. Based on the Gaussian approximation, the CL s value is easily calculated with ∆T (x), ∆T H0 , and ∆T H1 . In case any one of the above conditions breaks down, the parent distribution of ∆T (X) is not necessarily well approximated by the Gaussian distribution, and should instead be estimated through Monte Carlo simulations. We next demonstrate in detail the procedure of using the CL s approach based on the Gaussian approximation to set exclusion sets using a specific example.
B. Setting Exclusion Sets with the Gaussian CLs Method
In this section, we illustrate the procedure of setting exclusion sets with the Gaussian CL s method for the neutrino oscillation example from Sec. II. The null hypothesis is specified to be H 0 : (sin 2 2θ, |∆m 2 |, η) ∈ {(0, |∆m 2 0 |)} × H (e.g. the Standard Model with 3 neutrinos). Let x Asimov H0 denote the Asimov data set under the null hypothesis H 0 , which is exactly the expected mean counts corresponding to H 0 without any fluctuations of statistics nor variations of systematics. Ideally, when H 0 is correct, x Asimov H0 would be defined as µ(η 0 ), where η 0 stands for the true value of the nuisance parameter. But in practice, we do not know η 0 , so it is either approximated by the priorly known nominal value of the nuisance parameter (such as the term η 0 in Eq. (1)), or when the data size is large, by the minimizer of T H0 (x; η), denoted byη. Then for any (sin 2 2θ 1 , |∆m 2 1 |) from the parameter space Θ × M , one point at a time, we define H 1 : (sin 2 2θ, |∆m 2 |, η) ∈ {(sin 2 2θ 1 , |∆m 2 1 |)} × H, and repeat the following procedure:
1. For the observed data x, calculate
∆T (x) := T min H1 (x) − T min H0 (x).
For the Asimov data x Asimov
H0
, calculate
∆T H0 := ∆T (x Asimov H0 ) = T min H1 (x Asimov H0 ) − T min H0 (x Asimov H0 ) = T min H1 (x Asimov H0 ) ,(11)
where the last step holds because T min H0 (x Asimov . Then according to the main result that we prove in Sec. III C, under the null hypothesis H 0 , ∆T (X) follows approximately a Gaussian distribution with mean ∆T H0 and standard deviation 2 |∆T H0 |. This suggests that one calculates
1 − p 0 = 1 + Erf ∆TH 0 −∆T (x) √ 8|∆TH 0 | 2 ,(12)
where Erf(s) = 2 √ π s 0 e −t 2 dt denotes the Gaussian error function for any s ∈ (−∞, ∞).
Form the Asimov data set x Asimov
H1
, similar to how we formed x Asimov
H0
. Calculate
∆T H1 = ∆T (x Asimov H1 ) = T min H1 (x Asimov H1 ) − T min H0 (x Asimov H1 ) = −T min H0 (x AsimovH1
).
Then obtain
1 − p 1 = 1 + Erf ∆TH 1 −∆T (x) √ 8|∆TH 1 | 2 .(14)
4. According to Eq. (10), the CL s value at (sin 2 2θ 1 , |∆m 2 1 |) is given by:
CL s = 1 + Erf ∆TH 1 −∆T (x) √ 8|∆TH 1 | 1 + Erf ∆TH 0 −∆T (x) √ 8|∆TH 0 | .(15)
The point (sin 2 2θ 1 , |∆m 2 1 |) is assigned to the 95% CL s exclusion set if and only if its CL s is smaller than 5%,.
In terms of computing effort, the above CL s procedure requires the calculation of ∆T (x), ∆T H1 , and ∆T H0 at each phase space point in Θ × M . In comparison, the standard Chi-square method of setting confidence intervals with ∆χ 2 min (x) (Eq. (2)) requires the calculation of ∆χ 2 min (x) at each phase space point. So the computing cost of the Gaussian CL s method is at the same order (about three times) as that of the standard approach. This is typically considered a mild increment in computing effort in practice, and is worthy given the benefits of using the CL s method mentioned in Sec. III A.
C. A Gaussian Approximation to the Distribution of ∆T (X) with Large Data Size
A key component in the aforementioned CL s method is a Gaussian approximation to the parent distribution of ∆T (X). We prove the validity of such an approximation in this section. Specifically, we show that by omitting terms of relatively small orders, the distribution of ∆T (X) under the null hypothesis follows approximately the Gaussian distribution with mean ∆T and standard deviation 2 |∆T |.
Description of the mathematical problem and notations
Recall that we defined four versions of (T H0 (X; η), T H1 (X; ζ)) that correspond to four different definitions of the test statistic ∆T (X). In this section, we focus on studying ∆T (X) based on Eq. (7), namely the Pearson Chi-square statistic. For clarity, we call it D(X) from here on. The main part of Sec. III C 2 will be devoted to developing a Gaussian approximation for the parent distribution of D(X). And in the remarks in the end of Sec. III C 2, we show that the difference between the other three versions of ∆T (X) to D(X) are generally negligible, so that the approximate distribution derived for D(X) can also be used for all the different versions of ∆T (X).
We now clearly state the mathematical problem con-cerning D(X). Let
χ 2 H0 (X, η) := n i=1 (N i − µ i (η)) 2 µ i (η) and χ 2 H1 (X, ζ) := n i=1 (N i − ν i (ζ)) 2 ν i (ζ)(16)
and letη = arg min η χ 2 H0 (X, η) andζ = arg min ζ χ 2 H1 (X, ζ).
Then the definition of D(X) is
D(X) = χ 2 H1 (X,ζ) − χ 2 H0 (X,η) .(17)
Note our goal is to obtain an approximation of the distribution of D(X) when the data size is large. Hence a specific quantity, say m, is needed that reflects the magnitude of the data, in order that we can describe how other quantities in the model change along with it. For example, m could be the duration of the experiment or the total number of events. In the example of the search for a sterile neutrino in Sec. IV, m is the expected number of neutrino events seen by the detector without any oscillation per bin. It is also proportional to the total number of events and total duration of the experiment. For the ease of description, let m represent the duration of the experiment in this section. Then p = X m stands for the per unit time observed counts in a potential experiment, and it would remain stable (instead of tending to infinity or zero) as m grows. So we say p is of order O p (1) (with respect to m) 3 .
In order to describe the modeling of counts rigorously, we introduce a set of notations, a summary of which is provided in Table I. Recall we employed µ(η) to denote the vectors of the expected counts under the correct hypothesis of the model, where η is the vector of unknown nuisance parameters of dimension q. Denote the true value of η by η 0 , that is, µ 0 = µ(η 0 ) is the true expected counts of the observation such that
N i indep ∼ Poisson(µ 0 i ) for i = 1, · · · , n.
When the data size is large, a very good approximation to the model above is given by Further, let π := µ/m denote the per unit time expected counts. To help explain these notations, take the example from Sec. III B for instance, if H 0 : (sin 2 2θ, |∆m 2 |) = (sin 2 2θ 0 , |∆m 2 0 |) is the correct hypothesis, then q = dim(η) = 3, and π i = µ i (η)/m = a i (η) · P i + b i (η). The terms a i and b i are functions of order O(1), and are determined by the configuration of the experiment. For example, a i can represent the detector efficiency, neutrino flux from reactor, target mass, etc., b i can represent the backgrounds. Also, P i = 1 − sin 2 2θ 0 · sin 2 (1.27 · |∆m 2 0 | · L/E ν i ) represents the (disappearance) oscillation probability.
N i indep ∼ ≈ N(µ 0 i , µ 0 i ) for i = 1, · · · ,
In addition, a competing framework, namely the col-lection of models that satisfy H 1 , specifies the expected counts incorrectly as ν(ζ), where ζ is the unknown nuisance parameter of dimension q * . Also, define the per unit time expected counts under H 1 by τ = ν/m. Under H 1 , there exists a unique ζ 0 , such thatζ approaches ζ 0 as m → ∞. We will show in Appendix A that ζ 0 has the interpretation that it corresponds to the model ν(ζ) among all that belong to the alternative framework that is the closest to the true model µ 0 in terms of the deviation n i=1
(µ 0 i −νi(ζ)) 2 νi(ζ)
. Denote ν 0 = ν(ζ 0 ).
Approximating the distribution of the test statistic D(X)
In this section, we study the distribution of D(X) defined in Eq. (17). For convenience, we will suppress the dependence on X in the notation, and write D = χ 2 H1 (ζ) − χ 2 H0 (η). On one hand, it's well known that the distribution of χ 2 H0 (η) approaches the Chi-square distribution with degree of freedom (n − q) as m increases. On the other hand, the limiting distribution of χ 2 H1 (ζ) as m increases does not always exist. Specifically, the behavior of χ 2 H1 (ζ) for large m is dependent on how far apart the expected counts of the best model under the alternative theoretical frameworks are from that of the true model. Denote the difference of per unit expected counts between the two models by δ = π 0 − τ 0 . For all further investigation of χ 2 H1 (ζ), we make the following realistic assumption on δ:
[A0] δ = π 0 − τ 0 is a constant vector that does not change with m. We write
χ 2 H1 (ζ) = n i=1 (N i −ν i ) 2 ν i =: i f 2 i and χ 2 H0 (η) = n i=1 (N i −μ i ) 2 µ i =: i e 2 i .
Here
f i = f i (a, b, c) = N i −ν î ν 1 2 i = √ m p i −τ î τ 1 2 i = √ m (p i − π 0 i ) − (τ i − τ 0 i ) + (π 0 i − τ 0 i ) ((τ i − τ 0 i ) + τ 0 i ) 1 2 =: √ m a i − c i + δ i (c i + τ 0 i ) 1 2 , and e i = e i (a, b, c) = N i −μ î µ 1 2 i = √ m p i −π î π 1 2 i = √ m (p i − π 0 i ) − (π i − π 0 i ) ((π i − π 0 i ) + π 0 i ) 1 2 =: √ m a i − b i (b i + π 0 i ) 1 2 , where a i = p i − π 0 i = O p (m − 1 2 ), b i =π i − π 0 i , and c i =τ i − τ 0 i = O p (m − 1 2 )
, for i = 1, · · · , n. Then by the Taylor expansion of f = (f 1 , · · · , f n ) T and e = (e 1 , · · · , e n ) T around (a, b, c) = (0, 0, 0), we have
f = √ m diag{τ 0 } − 1 2 δ + diag{τ 0 } − 3 2 diag{τ 0 } − 1 2 diag{π 0 + τ 0 }E * √ m(p − π 0 ) + O p (m − 1 2 ) ,
where the three terms in the above expression are of order O p (m
e = diag{π 0 } − 1 2 (I − D) √ m(p − π 0 ) + O p (m − 1 2 ) , where D = B(B T diag{π 0 } −1 B) −1 B T diag{π 0 } −1 ,
and the two terms in the above expression are of order O p (1) and O p (m − 1 2 ) respectively. Therefore
D =χ 2 H1 (η) − χ 2 H0 (ζ) = f T f − e T e =m δ T diag{τ 0 } −1 δ + 2 √ m δ T diag{τ 0 } −2 diag{τ 0 } − 1 2 diag{π 0 + τ 0 }E * √ m(p − π 0 ) + O p (1) =m δ T diag{τ 0 } −1 δ + 2 √ m δ T diag{τ 0 } −1 √ m(p − π 0 ) − 1 2 √ m δ T diag π 0 + τ 0 (τ 0 ) 2 B * B * T diag (π 0 ) 2 (τ 0 ) 3 B * −1 B * T diag π 0 (τ 0 ) 2 √ m(p − π 0 ) + O p (1)
Under the correct model Under the alternative model
General notation
Mean bin counts µ(η) = (µ1(η), · · · , µN (η)) ν(ζ) = (µ1(ζ), · · · , µN (ζ)) Per-unit mean counts π(η) = µ(η)/m τ (ζ) = ν(ζ)/m
True values or their closest approximations under the give model nuisance parameter η0 (a q-dim vector) ζ0 (a q * -dim vector) Mean bin counts µ 0 = µ(η0) ν 0 = ν(ζ0) Per-unit mean counts
π 0 = µ 0 /m τ 0 = ν 0 /m
Estimation based on observed data nuisance parameterη = arg min χ 2 H 0 (X, η)ζ = arg min χ 2 H 1 (X, ζ) Mean bin countsμ = µ(η)ν = ν(ζ) Per-unit mean countsπ =μ/mτ =ν/m According to Eq. (27) of Lemma 1, the term in the closed bracket above reduces to 0. Hence
D = m δ T diag{τ 0 } −1 δ + 2 √ m δ T diag{τ 0 } −1 √ m(p − π 0 ) + O p (1) .
Denote the first term of D by
D 1 = m (π 0 − τ 0 ) T diag{τ 0 } −1 (π 0 − τ 0 ) = n i=1 (µ 0 i − ν 0 i ) 2 ν 0 i = min ν n i=1 (µ 0 i − ν i ) 2 ν i =: D ,(18)
where the second to last equality follows from Appendix A. Note that under assumption [A0], D 1 = D is of order O(m). Next denote the second term of D by D 2 . The central limit theorem implies that as m increases to infinity, √ m (p − π 0 ) converges in distribution to the N(0, diag{π 0 }) distribution. Hence D 2 /(2 √ m) converges in distribution to the N(µ 2 , V 2 ) where
µ 2 = δ T diag{τ 0 } −1 0 = 0 , and V 2 = δ T diag{τ 0 } −1 diag{π 0 }diag{τ 0 } −1 δ = δ T diag{(τ 0 ) −1 }δ + δ T diag{ π 0 − τ 0 (τ 0 ) 2 }δ = D m + n i=1 (π 0 i − τ 0 i ) 3 (τ 0 i ) 2 =: D m + s .
Remarks and Implications of Eq. (19) 1. Under certain conditions, further simplification can be made to the approximating distribution, N(D, 4D + 4ms), that we derived for D(X). For example, one of the common situations is when the null and the alternative hypothesis are relatively close to each other, that is, when |µ 0
i − ν 0 i | << µ 0 i ∼ ν 0 i .
In such situations, one can safely ignore the ms term, because ms = i 4D). (20) 2. We claimed in Sec. III A that, at large data limit, the three versions of ∆T (X) = T min H1 (X) − T min H0 (X) based on the definition of T H0 (and the corresponding T H1 ) in Eq. (5), (6), and (8), each have negligible difference from the ∆T (X) based on Eq. (7). And recall the last version of ∆T (X) is the Pearson Chi-square statistic that we named D(X). Now, we validate this claim.
(µ 0 i −ν 0 i ) 2 ν 0 i · µ 0 i −ν 0 i ν 0 i << i (µ 0 i −ν 0 i ) 2 ν 0 i = D. Then our main result becomes D approx. ∼ N (D,
For the moment, we drop the penalty term χ 2 penalty (η) from Eq. (5)-(8) for simplicity. And we will address the issue of the penalty term in the next remark.
First, for Eq. (5), we have,
T H0 (X) = i 2(µ i − N i + N i log N i µ i ) , = i 2(µ i − N i + N i log(1 − µ i − N i µ i ).
At large data limit,
|N i − µ i | = O p (µ 1 2 i ) = O p (m 1
2 ), we have by Taylor expansion,
log(1 − µ i − N i µ i ) = − µ i − N i µ i − (µ i − N i ) 2 2µ 2 i + O p (µ i − N i ) 3 µ 3 i = − µ i − N i µ i − (µ i − N i ) 2 2µ 2 i + O p m − 3 2 .
Therefore,
T H0 (X) = i 2 (µ i − N i ) 2 µ i · 1 2 + µ i − N i 2µ i + O p (m − 1 2 ) = i 2 (µ i − N i ) 2 µ i · 1 2 + O p (m − 1 2 ) = i (µ i − N i ) 2 µ i + O p (m − 1 2 ) .
Next, for Eq. (6), we have,
T H0 (X) = i (µ i − N i ) 2 µ i + log 1 + µ i − N i N i = i (µ i − N i ) 2 µ i + O p (m − 1 2 ).
Finally, for Eq. (8), we have,
T H0 (X) = i (µ i − N i ) 2 N i = i (µ i − N i ) 2 µ i 1 + µ i − N i N i = (µ i − N i ) 2 µ i + i (µ i − N i ) 3 µ i N i = i (µ i − N i ) 2 µ i + O p (m − 1 2 ).
After all, the difference between each version of T H0 (X) and i (µi−Ni) 2 µi are negligible, so will be the difference between each version of T H1 (X) and i (νi−Ni) 2 νi . It follows that the different versions of the test statistic ∆T (X) will behave similarly as D(X). Finally, it is easy to see that our definition for D is equivalent to ∆T based on Eq. (7). Hence all different versions of ∆T would bear similar numerical values as D. And our main result in Eq. (20) can be stated as
∆T approx. ∼ N (∆T , 4|∆T |).(21)
3. We emphasize that Eq. (17) is a general form of T in Eq. (5), (6), (7), and (8). The penalty term in T represents the constraint of systematic uncertainties, and is commonly obtained by dedicated measurements. When one includes the dedicated measurements as part of Chi-square definition, one naturally recovers Eq. (17). Therefore, our proof in Sec. III C is also valid for test statistics with the format of T in Eq. (5), (6), (7), and (8).
IV. A TOY EXAMPLE: SEARCH FOR STERILE NEUTRINO
In this section, we use a toy model to illustrate the Gaussian CL s method.
A. Model Description
In this toy model, there are two detectors. One detector locates at 300 kilo-meters from the neutrino source and is called the near detector. The other detector locates at 1000 kilo-meters from the neutrino source and is called the far detector. As shown in Fig. 4, the neutrino energy E ν covers from 1 GeV to 9 GeV. We further divide the entire energy range into 20 bins. A flat (energy independent) neutrino spectrum is assumed. The expected number of neutrino events seen by the near (far) detector without any oscillation is 10 k (0.9 k) per bin. We consider two types of oscillation measurements: a disappearance measurement with oscillation formula
P dis = 1 − sin 2 2θ · sin 2 1.27 · ∆m 2 L E ν ,(22)
and an appearance measurement with oscillation formula
P app = sin 2 2θ · sin 2 1.27 · ∆m 2 L E ν ,(23)
where θ is the neutrino mixing angle, ∆m 2 is the neutrino mass squared difference, and L is the neutrino travel distance. We further include a background with linear dependence on E ν . The number of background events starts from 130 per bin for the first bin to 73 per bin for the last (20th) bin. There are three nuisance parameters, ǫ, η n and η f . The first one is associated with the detector efficiency and the neutrino flux, which is assumed to be accurate to 5%. This uncertainty is assumed to be correlated between the near and the far detectors. The second and the third nuisance parameters are associated with the background normalization factors for the near and the far detectors, respectively. The normalization uncertainty is assumed to be 2% and uncorrelated between the two detectors. Fig. 4 shows the expected neutrino spectra. For the disappearance measurement, we compare the nooscillation spectrum (the null hypothesis H 0 : sin 2 2θ = 0) with an oscillation spectrum (an alternative hypothesis H 1 : sin 2 2θ = 0.06 at ∆m 2 = 2.5 × 10 −3 eV 2 ). For the appearance measurement, we compare the no-oscillation spectrum (the null hypothesis H 0 : sin 2 2θ = 0) with two oscillation spectra (two alternative hypotheses H 1 : sin 2 2θ = 0.008 or sin 2 2θ = 0.03 at ∆m 2 = 2.5 × 10 −3 eV 2 ). Given a toy Monte Carlo (MC) sample N j i , we use the following test statistic based on the Poisson likelihood, in line of Eq. (5):
T = j=n,f 20 i=1 2 µ j i (ǫ, η j , sin 2 2θ, ∆m 2 ) − N j i + N j i log N j i µ j i (ǫ, η j , sin 2 2θ, ∆m 2 ) + ǫ 2 0.05 2 + η 2 n 0.02 2 + η 2 f 0.02 2 .(24)
Here, i represents the bin number and runs from 1 to 20. j labels the near or the far detector. µ j i is the expected number of events in i-th bin and j-th detector. It depends on the oscillation parameters: sin 2 2θ and ∆m 2 , and the nuisance parameters: ǫ for the detector efficiency and neutrino flux, η n (η f ) for the near (far) detector background normalization factors.
B. Feldman-Cousins vs. Wilks
For the toy example mentioned above, we provided a theoretical argument in Sec. II stating that conditions required by the Wilks' Theorem are violated, hence the Chi-square method is unsuitable for setting CI for the parameter sin 2 2θ. Instead, the computationally intensive Feldman-Cousin method is always valid and need to be used to set CI in this example. The purpose of this section is to demonstrate the practical difference between the two methods. Since the Chi-square method is especially problematic when one needs to decide if 0 or values close to 0 should be in a CI for sin 2 2θ, we consider the problem of checking the value 0. We need the parent distribution of the test statistic in Eq. (25) under the hypothesis H 0 : sin 2 2θ = 0. To implement the Feldman-Cousin method, we generate a large number of MC samples assuming that sin 2 2θ = 0. The MC samples have statistical fluctuations according to Poisson distributions, and systematic variations through randomizing the three nuisance parameters according to normal distributions. Given each MC sample, we find T min and T min H0 which are the minimum value of T from Eq. (24) in the 5-dimensional phase space of (sin 2 2θ, ∆m 2 , ǫ, η n , η f ), and the minimum value of T under the restriction, sin 2 2θ true = 0, respectively. Then we form the test statistic
∆χ 2 min = T min H0 − T min .(25)
Fig . 5 shows the distribution of ∆χ 2 min , which clearly does not follow a Chi-square distribution with two degrees of freedom. That is, to correctly set confidence intervals with the test statistic ∆χ 2 min , the Chi-square method can not be used, and one has to resort to the computationally intensive Feldman-Cousin method.
C. Validity of the Gaussian Approximation in the Gaussian CLs method
Having seen that there is no fast way to implement the CI approach, we turn to the CL s approach. In this section, we study the performance of the Gaussian CL s method that we proposed. Specifically, we check how closely does the CL s test statistic ∆T = T min H1 − T min H0 follow the normal distribution N(∆T ,4∆T ). Here, T min H is the value of the test statistic T from Eq. (24) under the hypothesis H, minimized over the nuisance parameters (ǫ, η n , η f ). Fig. 6 shows the distribution of ∆T for the disappearance measurement. The null hypothesis H 0 corresponds to sin 2 2θ = 0. The alternative hypothesis H 1 Similarly, we also check the appearance measurements. In Fig. 7, the null hypothesis H 0 corresponds to sin 2 2θ = 0, and the alternative hypothesis H 1 corresponds to (sin 2 2θ, ∆m 2 ) = (0.008, 2.5 × 10 −3 eV 2 ). In Fig. 8, H 0 corresponds to sin 2 2θ = 0, and H 1 corresponds to (sin 2 2θ, ∆m 2 ) = (0.03, 2.5 × 10 −3 eV 2 ). The agreement between the MCs and expectations in Fig. 7 is slightly worse than that in Fig. 6, but is still reasonably good. However, the difference between the MCs and expectations in Fig. 8 becomes large. This is because the third regularity condition "when the prediction of two hypotheses (the null hypotheses H 0 and the alternative hypothesis H 1 are relatively close or |µ i −ν i | << µ i ∼ ν i " is no longer met. In a disappearance measurement, this condition can easily satisfied. However, this may not be true in an appearance experiment as the expected number of signal events is zero when sin 2 2θ = 0. This could be much smaller than the expected number of signal events with oscillations. When H 0 and H 1 are sin 2 2θ = 0 and (sin 2 2θ, ∆m 2 ) = (0.008, 2.5×10 −3 eV 2 ), respectively, this condition is still reasonably well satisfied with the existence of backgrounds. But when H 0 and H 1 are sin 2 2θ = 0 and (sin 2 2θ, ∆m 2 ) = (0.03, 2.5 × 10 −3 eV 2 ), respectively, this condition is much more severely violated. Note that in such situations where H 0 and H 1 are very different, the experimental data is most likely able to exclude one hypothesis easily, making it less interesting to carry out an accurate statistical test. Nevertheless, we emphasize it is crucial to check with MCs whether the Gaussian approximation is valid in practice. is plotted for toy MCs (appearance) assuming the hypothesis H0 or H1 is true. Here, the null hypothesis H0 corresponds to sin 2 2θ = 0. The alternative hypothesis H1 corresponds to sin 2 2θ = 0.008 and ∆m 2 = 2.5 × 10 −3 eV 2 . is plotted for toy MCs (appearance) assuming the hypothesis H0 or H1 is true. Here, the null hypothesis H0 corresponds to sin 2 2θ = 0. The alternative hypothesis H1 corresponds to sin 2 2θ = 0.03 and ∆m 2 = 2.5 × 10 −3 eV 2 .
D. CLs vs. p-value
In the following, we use the disappearance experiment to compare the CL s approach with its alternatives. With the new test statistic ∆T = T min H1 −T min H0 , one can in principle still follow the method of using p-value to set confidence intervals assuming the null hypothesis H 0 . Fig. 9 compares confidence intervals set with p-values against exclusion sets obtained with CL s values, both using the test statistic ∆T . The true sin 2 2θ is assumed to be zero. The sensitivity of the Gaussian CL s method is slightly worse than that of the p-value method, because the CL s value is by construction larger than the corresponding p-value. Despite the slightly worse sensitivity, the advantage of the CL s method becomes clear when analyzing data. As shown in Fig. 9, the region that correspond to ∆m 2 ∼ 5.5 × 10 −2 eV 2 and sin 2 2θ < 0.01 (also ∆m 2 ∼ 0.1 eV 2 and sin 2 2θ < 0.01) is excluded from the 95% confidence interval according to the p-value method. This is inconsistent with intuition as the expected spectrum for small sin 2 2θ values should be very similar to that of sin 2 2θ = 0, and we do not expect to exclude regions with sin 2 2θ values. This phenomenon can be understood as the following. With the test statistic ∆T , we compare two hypotheses each time. Therefore, even when the two hypotheses are very similar, the chance of excluding one hypothesis with the p-value method can still be large as illustrated in Fig. 3. As we explained in Sec. III A, the definition of the CL s value avoid this problem, giving it an advantage over the traditional p-value method when test statistic ∆T is used.
E. The Gaussian CLs method vs. Feldman-Cousins CI method
We further compare the Gaussian CL s method with the Feldman-Cousins' CI method. Fig. 10 compares the sensitivity of the Gaussian CL s method vs. that of the Feldman-Cousins CI method. We assumed that the true value of sin 2 2θ is 0. The sensitivity of the 95% exclusion set from the Gaussian CL s method is slightly better than that of the 95% confidence interval from the Feldman-Cousins' method, and is actually close that of the 90% confidence interval from the Feldman-Cousins' method for this setup. This can be understood, since the test statistic ∆T = T min H1 − T min H0 used in the Gaussian CL s method is designed to focus on the difference between the new physics hypotheses (the alternative hypothesis: sin 2 2θ > 0) with the standard model (the null hypothesis: sin 2 2θ = 0). Therefore, when the true value of sin 2 2θ is 0, the power of excluding new physics hypotheses with the Gaussian CL s method is stronger than that of the Feldman-Cousins' CI method. On the other hand, when the new physics is indeed true, the Feldman-Cousins' CI method has a clear advantage in constraining the parameter space. This is shown in Fig. 11. The toy MC sample is generated with sin 2 2θ true = 0.1 and
= T min H 1 − T min H 0 .
The true value of sin 2 2θ is 0. For the p-value (CLs) method, the right side of the red (black) line has a p-value (CLs value) smaller than 0.05. The sensitivity curves are generated from a large number of Monte Carlo samples. At each ∆m 2 , 50% (50%) of toy MC samples will have a better (worse) exclusion limit than the sensitivity curve. ∆m 2 true = 2.5 × 10 −3 eV 2 with statistical fluctuations and systematic variations. The 90% confidence interval of the Feldman-Cousins method clearly picked up the region close to the true value. However, the 5%-95% CL s interval is much broader. This again is due to the choice of the test statistic (∆T in the Gaussian CL s method vs. ∆χ 2 min in the Feldman-Cousins' CI method). On the other hand, the constraint of sin 2 2θ for ∆m 2 values around 2.5 × 10 −3 eV 2 with the Gaussian CL s method is tighter than that of the Feldman-Cousins' method. This can also be understood since the proposed test statistic ∆T focuses on the difference between the new physics hypothesis and the standard model, while the test statistic ∆χ 2 min takes into account all the possibilities around the tested true (sin 2 2θ true , ∆m 2 true ) point. At other ∆m 2 values, the performance of the test statistic ∆T is clearly worse than that of the test statistic ∆χ 2 min . Therefore, we confirm the conclusion from Ref. [1]: "the CL s technique for setting limits is appropriate for determining exclusion sets while the determination of confidence intervals advocated by Feldman and Cousins' method is more appropriate for treating established signals".
V. DISCUSSION
As shown in Sec. IV, the test statistic ∆χ 2 min (X) clearly does not follow the Chi-square distribution with two degrees of freedom (Fig. 5). In Sec. II, we explained that this is because certain regularity conditions of the Wilks' theorem are not satisfied. Firstly, sin 2 2θ = 0 is at the boundary of the allowed physical phase space, thus the condition on the continuity of the parameter space does not hold. Secondly, at sin 2 2θ = 0, due to the large coverage of |∆m 2 | shown in Fig. 1b, the data size is not large enough to ensure that ∆χ 2 min has a parabolic shape in the close neighborhood of its minimum (sin 2 2θ min , |∆m 2 | min ). In contrast, if we use the test statistic ∆T , then its distribution agrees well with the Gaussian distribution with mean and standard deviation of ∆T and 2 |∆T |, respectively ( Fig. 6 and Fig. 7). This is not surprising given that all three regularity conditions required for the Gaussian approximation in Sec. III A are satisfied. The first condition requires continuity of the phase space for the nuisance parameters, under the null and the alternative hypotheses, respectively. This is easily satisfied since the requirement concerns the nuisance parameters only, not the parameters of interest, (sin 2 2θ, |∆m 2 |). The second condition concerns large enough data size, which can be reached relatively easily compared to the large data size required by the Wilks' theorem. This is because in the Gaussian CL s method we are concerned with testing a simpler pair of hypotheses, where the value of (sin 2 2θ, |∆m 2 |) are fixed, and one automatically avoids the situation shown in Fig. 1b that requires performing minimization over a large range of |∆m 2 | in calculating the test statistic. The third condition requires that the fixed values of (sin 2 2θ, |∆m 2 |) assumed by the two hypotheses are relatively close. This condition can be violated when one tries to exclude certain values of (sin 2 2θ, |∆m 2 |), and the performance of the Gaussian approximation does deteriorate, as seen in Fig. 8. Therefore, we emphasize that one could always use the Monte Carlo simulation method to check validity of results based on the Gaussian CL s . And in situations where conditions of the Gaussian CL s method are clearly violated, one should rely on the Monte Carlo simulation results.
As discussed in Ref. [1] and shown in Sec. IV, the CL s method is complementary to the confidence interval method: CL s is appropriate to set exclusion limit while the confidence interval is appropriate in treating established signals. While the exclusion limit set by CL s method is always valid, it did not directly address the question "do we see new physics or not". To address this question, we recommend to report the p-value calculated by the test statistic ∆χ 2 min assuming the standard model is true.
Similar to the Chi-square CI method with test statistic ∆χ 2 min and predefined constants, the Gaussian CL s method also allows easy combination of multiple independent experimental results that probe the same phase space. The CL s value at each alternative hypothesis In practice, the main challenge in combining multiple experiment results arise from the potential correlation among different experiments and requires careful examination.
VI. SUMMARY
In this paper, we describe a new method to present results in searching for new physics in a continuous parameter space. This method is based on the CL s approach that is complementary to the traditional confidence interval approach. Many pairs of hypotheses need to be tested when setting exclusion sets with the CL s approach. For each two-hypotheses testing problem, we consider the log-likelihood ratio test statistic, and certain variations of it, denoted by ∆T . We provide a rigorous mathematical proof that, the parent distribution of ∆T follows a Gaussian distribution at large data limit when the two hypotheses are relatively close. This approach can be used to calculate the CL s value and thus setting exclusion limits in one or multiple dimensional parameter space without intense Monte Carlo simulations. This approach can also be used to conveniently combine results from multiple experiments.
VII. ACKNOWLEDGMENTS a.s. to arg min ζ t(ζ) as m increases. By denoting the limit ofζ m by ζ 0 , we have mt(ζ 0 ) = min ζ mt(ζ). That is, ζ 0 and ν 0 := ν(ζ 0 ) are such that n i=1
(µ 0 i −ν 0 i ) 2 ν 0 i = min ν n i=1 (µ 0 i −νi) 2 νi .
We list a few more properties that are useful in the proof of Lemma 1 and the proof of the result in Eq. (19). It is well-known thatη − η 0 andπ − π 0 are both of order O p (m − 1 2 ). Andζ − ζ 0 andτ − τ 0 are also both of order O p (m − 1 2 ) according to [20].
τ − τ 0 = I E * √ m p − π 0 + O p (m − 1 2 ) ,(26)
where
E * = B * B * T diag (π 0 ) 2 (τ 0 ) 3 B * −1 B * T diag π 0 (τ 0 ) 2 and B * n×q * = ∂τ 0 ∂ζ .
Further,
B * T diag (π 0 + τ 0 ) (τ 0 ) 2 δ = 0 .(27)
Proof. By definition,ζ is such that ∂χ 2 H1 (ζ) ∂ζ j = 0 for j = 1, · · · , q * .
That is,
2 n i=1 N i +ν î ν 2 i ∂ν i ∂ζ j (N i −ν i ) = 0 n i=1 N i +ν î ν 2 i ∂ν i ∂ζ j (N i − ν 0 i ) = n i=1 N i +ν î ν 2 i ∂ν i ∂ζ j (ν i − ν 0 i ) n i=1 p i +τ î τ 2 i ∂τ i ∂ζ j (p i − π 0 i + π 0 i − τ 0 i ) = n i=1 p i +τ î τ 2 i ∂τ i ζ j (τ i − τ 0 i ) .(28)
Note by delta's method
τ i = τ 0 i + k ∂τ 0 i ∂ζ k (ζ k − ζ 0 k ) + O p (m −1 )
and
∂τ i ζ j = ∂τ 0 i ζ j + k ∂ 2 τ 0 i ∂ζ j ∂ζ k (ζ k − ζ 0 k ) + O p (m −1 ) , and p i +τ i (τ i ) 2 − π 0 i + τ 0 i (τ 0 i ) 2 = 1 (τ 0 i ) 2 (p i − π 0 i ) − 1 (τ 0 i ) 2 (2 π 0 i τ 0 i + 1)(τ i − τ 0 i ) + O p (m −1 ) . Hence √ m(ζ − ζ 0 ) = (B * T diag (π 0 ) 2 (τ 0 ) 3 B * ) −1 B * T diag π 0 (τ 0 ) 2 √ m p − π 0 + O p (m − 1 2 ) =: P * √ m p − π 0 + O p (m − 1 2 ) . (30) Therefore √ m(τ − τ 0 ) = ( ∂τ 0 ∂ζ + O p (m − 1 2 ))P * √ m p − π 0 + O p (m − 1 2 ) = B * P * √ m p − π 0 + O p (m − 1 2 ) =: E * √ m p − π 0 + O p (m − 1 2 ) .(31)
Hence
√ m p − π 0 τ − τ 0 = I E * √ m p − π 0 + O p (m − 1 2 ) .
FIG. 1 .
1(color online) Left panel (a): The phase space of sin 2 2θ vs. |∆m 2 | in the Cartesian coordinate. Physical constraints are sin 2 2θ ≥ 0 and |∆m 2 | ≥ 0. Right panel (b): Schematic illustration of the effective phase space of sin 2 θ vs. |∆m 2 | taking into account the spectral difference measured by χ 2 defined in Eq. (1). When sin 2 2θ = 0, points with different values of |∆m 2 | will converge into a single point. This can be easily seen from Eq. (4). At sin 2 2θ = 0, |∆m 2 | has no impact on the neutrino spectrum.
FIG. 2 .
2FIG. 2. (color online) Illustration of the CLs approach with log-likelihood ratio ∆T . In order to be consistent with the convention in Ref. [15], we plot the densities of −∆T instead. The black curve represents the density when the null hypothesis is true, the red curve represents the density when the alternative hypothesis (new physics) is true, and the most probable value of the black curve (e.g. the peak) would be positioned to the left of the most probable value of the red curve. The green line is positioned at −∆T (x), where x is the observed data. Hence p0 is the probability of seeing potential observations that yield a −∆T value larger than −∆T (x). Similarly, 1 − p1 is the probability of seeing potential observations that lead to a −∆T value smaller than −∆T (x).
FIG. 3 .
3(color online) Same asFig. 2except that the null hypothesis H0 and the alternative hypothesis H1 are very close to each other.
the definition of T min H0 and x AsimovH0
1 2
1), O p (1) and O(m − 1 2 ) respectively. Further,
Note that both D m and s are of order O(1) under assumption [A0], hence D 2 = O p (m 1 2 ). In summary, under assumption [A0], we have D = D 1 + D 2 + O p (1
FIG
. 4. (color online) Top panels show the expected number of events seen at the near and far detector in a disappearance experiment. Bottom panels show the expected number of events seen at near and far detector in an appearance experiment. Left and right panels show near and far detectors, respectively. See text for more explanations.
5. (color online) Distribution of ∆χ 2 min = T (sin 2 2θ = 0) − Tmin is plotted for toy MCs with the true sin 2 2θ = 0. The distribution is compared to the Chi-square distribution with two degrees of freedom.corresponds to sin 2 2θ = 0.06 and ∆m 2 = 2.5×10 −3 eV 2 . The histograms on the left (right) are made from the toy MC samples assuming H 1 (H 0 ) is true. We also compare them with the expected normal distribution N(∆T ,4∆T ) from the ∆T H0 and ∆T H1 calculated from the Asimov data sets. Good agreements are observed.
FIGFIG
. 6. (color online) The test statistic ∆T = T min H 1 − T min H 0 is plotted for toy MCs (disappearance) assuming the hypothesis H0 or H1 is true. Here, the null hypothesis H0 corresponds to sin 2 2θ = 0. The alternative hypothesis H1 corresponds to sin 2 2θ = 0.06 and ∆m 2 = 2.5 × 10 −3 eV 2 . . 7. (color online) The test statistic ∆T = T min H 1 − T min H 0
FIG
. 8. (color online) The test statistic ∆T = T min H 1 − T min H 0
FIG
. 9. (color online) Comparison of the exclusion sets determined by the Gaussian CLs method vs. the CI determined by the p-value method, both using the test statistic ∆T
FIG
. 10. (color online) Comparison of the sensitivity of the 95% Gaussian CLs method vs. that of the 95% and the 90% Feldman-Cousins' CI method. The true value of sin 2 2θ is 0.
FIG
. 11. (color online) Comparison of the 90% confidence intervals from the Feldman-Cousins' method vs. 5%-95% interval from the Gaussian CLs method for a toy MC sample generated with sin 2 2θtrue = 0.1 and ∆m 2 true = 2.5 × 10 −3 eV 2 .
the combined data from all experiments. This can be easily achieved if each experiment releases their maps of T x k , ∆T (x Asimov H1 ), and ∆T (x Asimov H0 ).
n. The Big O, the small o, the Big Op, and the small op notation are standard mathematical symbols, such that for two sequences of random variables {Xm} and {Ym}, we write • Ym = op(Xm) if and only if Ym/Xm → 0 in probability as m → ∞, and • Ym = Op(Xm) if and only if Ym/Xm is bounded in probability as m → ∞ . In the special case where {Xm} and {Ym} are deterministic sequences, the stochastic op and Op symbols reduce to the o and O symbols. See [19, sec 2.2] for details on the rules of calculus with these symbols.3
TABLE I .
ILegend of symbols used in describing the correct model and the alternative model, respectively.
In the case where the null hypothesis H 0 and the alternative hypothesis H 1 are very similar (as shown inFig. 3), a close to one CLs value does not indicate H 1 is favored over H 0 .
We would like to thank Wei Wang for helpful discussions. This material is based upon work supported by the National Science Foundation and the U.S. Department of Energy, Office of Science, Office of High Energy Physics, Early Career Research program under contract number DE-AC02-98CH10886.APPENDICESA. A few basic properties of the fitted models under H0 and H1Suppose H 0 is the correct hypothesis, that is, the data X came from H 0 . Having observed the data, the best fitting models under H 0 and H 1 have estimated nuisance parametersη andζ respectively, as defined in Sec. III. The corresponding per unit expected counts are denoted π andτ respectively. We show below that there is a unique limit ofζ as the data size increases, and that it leads to the model ν(ζ) that is the closest model under . Since p converges almost surely (a.s.) to π 0 as m increases, we have t m (ζ) converges a.s. to t m (ζ). Then under regularity conditions, such as t m being twice differentiable and convex in ζ,ζ m = arg min ζ t m (ζ) also convergesThe rhs of Eq. (28) becomesHence, equating lhs and rhs leads to, for j = 1, · · · , q * ,Note that, under assumption [A0], all the terms are O p (m − 1 2 ) or smaller except for the first term on the lhs. Letting m grow to infinity in Eq. (29) implies thatwhich in matrix notation becomeswhich proves Eq. (27) of Lemma 1. Plugging this result back into Eq. (29), we have 0 + 2B * T diag π 0 (τ 0 ) 2 p − π 0 = B * T diag (π 0 + τ 0 )τ 0 + (2π 0 + τ 0 )(π 0 − τ 0 ) (τ 0 ) 3 B * (ζ − ζ 0 ) + O p (m −1 ) .That is
Presentation of search results: The CL(s) technique. Alexander L Read, J.Phys. 28Alexander L. Read. Presentation of search results: The CL(s) technique. J.Phys., G28:2693-2704, 2002.
. G Aad, Phys. Lett. 716G. Aad et al. Phys. Lett., B716, 2012.
. S Chatchyan, Phys. Lett. 716S. Chatchyan et al. Phys. Lett., B716, 2012.
. A Aguilar-Arevalo, Phys. Rev. 64112007A. Aguilar-Arevalo et al. Phys. Rev., D64:112007, 2001.
. A A Aguilar-Arevalo, Phys. Rev. Lett. 11016A. A. Aguilar-Arevalo et al. Phys. Rev. Lett., 110:16, 2013.
. G Mention, Phys. Rev. 8373006G. Mention et al. Phys. Rev., D83:073006, 2011.
. K Nakamura, J. Phys. 3775021K. Nakamura et al. J. Phys., G37:075021, 2010.
Modified frequentist analysis of search results (The CL(s) method). Alexander L Read, Alexander L. Read. Modified frequentist analysis of search results (The CL(s) method). 2000.
Statistical Evaluation of Experimental Determinations of Neutrino Mass Hierarchy. X Qian, A Tan, W Wang, J J Ling, R D Mckeown, Phys.Rev. 863651X. Qian, A. Tan, W. Wang, J.J. Ling, R.D. McKe- own, et al. Statistical Evaluation of Experimental De- terminations of Neutrino Mass Hierarchy. Phys.Rev., D86:113011, 2012, 1210.3651.
Quantifying the sensitivity of oscillation experiments to the neutrino mass ordering. Mattias Blennow, Pilar Coloma, Patrick Huber, Thomas Schwetz, JHEP. Mattias Blennow, Pilar Coloma, Patrick Huber, and Thomas Schwetz. Quantifying the sensitivity of oscilla- tion experiments to the neutrino mass ordering. JHEP, 1403:028, 2014, 1311.1822.
. S S Wilks, The Annals of Mathematical Statistics. 9S. S. Wilks. The Annals of Mathematical Statistics, 9, 1938.
A Unified approach to the classical statistical analysis of small signals. J Gary, Robert D Feldman, Cousins, Phys.Rev. 579711021Gary J. Feldman and Robert D. Cousins. A Unified ap- proach to the classical statistical analysis of small signals. Phys.Rev., D57:3873-3889, 1998, physics/9711021.
. G Cowan, Eur. Phys. J. 711554G. Cowan et al. Eur. Phys. J., C71:1554, 2011.
Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay. F P An, 1310.6732Phys.Rev.Lett. 11261801F.P. An et al. Spectral measurement of electron antineu- trino oscillation amplitude and frequency at Daya Bay. Phys.Rev.Lett., 112:061801, 2014, 1310.6732.
Open statistical issues in Particle Physics. Louis Lyons, Ann. Appl. Stat. 2Louis Lyons. Open statistical issues in Particle Physics. Ann. Appl. Stat., 2:887-915, 2008.
Prospects for the measurement of muon-neutrino disappearance at the FNAL-Booster. A Anokhina, A Bagulya, M Benettoni, P Bernardini, R Brugnera, A. Anokhina, A. Bagulya, M. Benettoni, P. Bernardini, R. Brugnera, et al. Prospects for the measurement of muon-neutrino disappearance at the FNAL-Booster. 2014, 1404.2521.
Search for a Light Sterile Neutrino at Daya Bay. F P An, 1407.7259F.P. An et al. Search for a Light Sterile Neutrino at Daya Bay. 2014, 1407.7259.
Clarification of the Use of Chi Square and Likelihood Functions in Fits to Histograms. Steve Baker, Robert D Cousins, Nucl.Instrum.Meth. 221Steve Baker and Robert D. Cousins. Clarification of the Use of Chi Square and Likelihood Functions in Fits to Histograms. Nucl.Instrum.Meth., 221:437-442, 1984.
Van der Vaart. Asymptotic Statistics. The Press Syndicate of the University of Cambridge. A W , A. W. Van der Vaart. Asymptotic Statistics. The Press Syndicate of the University of Cambridge, 1998.
Maximum Likelihood Estimation of Misspecified Models. H White, Econometrica. 50H. White. Maximum Likelihood Estimation of Misspec- ified Models. Econometrica, 50, 1982.
| [
-0.16975082457065582,
-0.059291109442710876,
0.08535701781511307,
0.15304647386074066,
0.12261662632226944,
-0.06624588370323181,
-0.0869365930557251,
0.12851844727993011,
0.025927620008587837,
0.03843357414007187,
0.13360267877578735,
-0.03783812373876572,
0.06739512830972672,
-0.06583161... |
Supplementary Materials and Methods
Supplementary Materials and Methods
Cell lines and culturing conditions. Melanoma cell lines were kindly provided by Dr.Meenhard Herlyn at the Wistar Institute (Philadelphia, PA). Non-small cell lung cancer cell lines H23 and H838 were obtained from Dr. Charles Rudin's lab and H1395 from Dr. Craig Peacock's lab at Johns Hopkins University (JHU). Glioblastoma cell lines were obtained from Dr. Greg Riggins' lab at JHU. Melanoma and glioblastoma cells were maintained in Dulbecco's modified Eagle medium. NSCLCs were maintained in RPMI medium 1640. Both types of media were supplemented with 10% fetal bovine serum (FBS), penicillin-streptomycin (pen-strep), and L-glutamine. The media, pen-strep, and L-glutamine were purchased from Invitrogen. FBS was obtained from Gemini Bio-Products (#100106).Cell treatment for 3 H-thymidine incorporation.Cells were plated in 96-well plates at subconfluency and allowed to attach to the plate surface prior to treatment with 10 M C646, 10 M C37, or 0.01% DMSO for 24 h. Following treatment, 3 H-thymidine (1 mCi/ml stock) was added to media at 10 μCi/ml. Cells were incubated in this media for an additional 5 h and then trypsinized and collected onto a filter mat for radioactivity measurement.XTT assay. The assay was performed using the Cell Proliferation Kit II (XTT) according to manufacturer's protocol (Roche). Cells were seeded in 96-well plates at low confluency and treated with molecules of interest for 9 days. Cell culture media was changed every other day with the addition of fresh compounds. Absorbance measurements were taken on days 1, 3, 6, 7 and 9.
Cell cycle analysis. Cells were treated with C646 or DMSO for 24 h. Equal numbers of cells (1x10 6 ) from each sample were then collected and fixed in 70% ethanol for at least 2 h at 4 o C and washed with PBS. The cells were then stained for ~20 min at 37 o C with a solution containing 0.02 mg/ml PI, 0.1% Triton X-100 and ~20 units/ml RNase A (Ambion RNase Cocktail #AM2286, 200 l for 5 ml staining solution) in PBS. The stained cells were then immediately analyzed using flow cytometry.
Quantitative real time PCR. qPCR was performed using the Power SYBR Green PCR Master Mix (ABI) for both microarray validation and ChIP DNA analyses. PCR was run at 95 o C for 5 min, followed by 40 cycles at 95 o C for 15 sec, annealing for 30 sec, and 72 o C for 30 sec per cycle, followed by a melt curve stage. The annealing temperature for all the microarray validation PCRs was 60 o C. For ChIP-qPCR, the annealing temperatures were between 58 o C and 60 o C, depending on the primers. Each sample had four replicates. PCRs were performed with real time systems from ABI and data acquisition was done with ABI's proprietary softwares.
Further data analysis was done in Excel. On the graphical representations of PCR quantification, the error bars represent the difference between the mean RQ (relative quantity) values and the maximum or the minimum values (+ error and -error, respectively).
Gene expression values were determined with the Ct method using ABI's softwares. To control for variations in DNA amount between wells, GAPDH was used as the internal control.
For the microarray validation PCRs on gene transcripts, DMSO-treated samples were used as the reference for data normalization. The graphs represent mean RQ values after such normalization. For ChIP-qPCR, DMSO treated samples from total histone H3 pulldown was used to normalize all DMSO ChIP data, and C646-treated samples from total H3 pulldown was used to normalize all C646 samples. This was done to account for any differences in the amount of chromatin pulled down by the H3 antibody between DMSO-and C646-treated cells.
Therefore, data from ChIP-qPCR were represented as %total H3, which were equal to mean RQ*100.
Chromatin immunoprecipitation. ChIP was performed based on a published protocol (O'Geen, Frietze and Farnham, 2010). Formulations for all buffers are taken from the protocol.
Briefly, the cells were cross-linked with 0.37% formaldehyde for 10 min at room temperature (RT) with agitation. Nuclei were initially released by lysing the cells on ice for 15-30min followed by centrifugation at 430xg for 5 min at 4 o C. The nuclei were then lysed on ice for an additional 30 min. Vigorous pipetting during the two lysis steps was sufficient to break up the cells. The chromatin was sheared using the Bioruptor (Diagenode) at the high power setting for 30 min with a 30-sec pulse followed by a 1.5-min cool down between cycles. The immunoprecipitation was conducted overnight at 4 o C with antibodies against acetylated H3, total H3, and p300.
Approximately 10% of the total chromatin for one ChIP was saved as the input before the IP.
The bound chromatin was collected with magnetic Protein G beads and washed. The cross-link was reversed in 0.54 M NaCl, and the DNA was then purified with a PCR clean up kit and redissolved in 50 l H 2 O. Each PCR reaction used 1 l of the DNA.
Western blot. For the analysis of growth regulatory proteins, cells were treated with DMSO, 10 and 20 M of C646, and 20 M of C37 for 24 h. Whole cell lysate was then prepared by incubating cells in lysis buffer containing 50 mM Tris•Cl (pH 7.5), 250 mM NaCl, 5 mM EDTA and 0.1% IGEPAL, supplemented with protease inhibitors (Sigma #P8340) and PMSF, on ice for ~20 min. Standard SDS-PAGE gel electrophoresis was used to separate the proteins, which were then transferred onto PVDF membranes. Ponceau S staining of the blots was done to verify complete transfer.
For the analysis of H2AX, cells were treated for 24 h as above and the nuclei were first separated from the cytoplasm by incubating trypsinized cells with a buffer containing 10 mM Tris•Cl (pH 7.4), 10 mM NaCl, 3 mM MgCl 2 and 0.5% IGEPAL for 10-15 min on ice. The nuclear fraction was then pelleted at 430xg and 4 o C for 5 min. The histones were extracted with 0.4 N sulfuric acid overnight at 4 o C, followed by precipitation with trichloroacetic acid, acetone washes, and resuspension in water. SA--gal assay. Cells were plated in 12-well plates at a density of ~16,000 cells /well for the C646 treatment and ~4000 cells/well for the DMSO treatment. After 24 hours the cells were treated with 20 M C646 or DMSO. C646 or DMSO was added every 24 h for 4 days. Cells were stain for -galactosidase following the manufacturer protocol (#9860, Cell Signaling Technology). In brief, the media were removed and the cells were washed with PBS. The cells were then fixed with 1X Fixative solution from the kit for 15 min at RT. After fixation, the cells were washed 2 X with PBS and stained with -galactosidase Staining Solution for 48 h in a 37°C incubator without CO 2 . Cells were observed under a light microscope and -gal positive cells had a blue perinuclear staining pattern. Pictures were taken under an Olympus IX71 inverted wide-field epifluorescence microscope with a Zeiss Axiocam MRc5 color camera and Zeiss Axiovision imaging software. Finally, the cells were rinsed 3 times with 0.5% BSA/PBS and once with PBS alone. The slides were mounted using VECTASHIELD Mounting Medium with DAPI (#H-1200, Vector Labs) and examined under 40× magnification using a Nikon Eclipse E400 microscope equipped with a RTKE SPOT digital camera (Diagnostic Instruments, Inc.). FITC and DAPI images were overlapped using the Advanced SPOT software.
Flow cytometry for annexin V/PI stained cells. Cells
C646/cisplatin combination treatment. WM35 cells were pre-treated with DMSO or C646 at 10 or 20 M for 24 h, followed by a medium change and a 48 h recovery period. Then, the cells were treated with water or 20 M cisplatin for an additional 48 h, collected, and fixed in 1% paraformaldehyde on ice. The cells were then washed in PBS, resuspended in 0.5 ml PBS plus 5 ml 70% ethanol, and stored at -20 o C overnight before the TUNEL assay. The assay was performed using the APO-BrdU TUNEL Assay Kit (Invitrogen A35125) following the manufacturer's protocol. After staining, the cells were incubated with the PI/RNase solution from the kit for 30 min before FACS analysis. The -actin primers were as follows: (Forward) 5'-GCATTGTTACAGGAAGTCC-3'; (Reverse) 5'-CATTACATAATTTACACGAAGC-3'. To assess the effect of CCNA2 knockdown on cell proliferation, the MTT assay was performed on WM35 cells transfected with the siRNAs (CCNA2 siRNAs or scrambled siRNA) and the untransfected cells. The cells were seeded in triplicates in 24-well plates and analyzed after 96 h. Specifically, 50 l of 5 mg/ml MTT was added to each well with a total medium volume of 500 l, and the cells were incubated in the regular CO 2 incubator at 37 o C for 2 h. The medium was then carefully removed and the MTT solvent was added. The plate was covered with tinfoil and the cells were agitated on a shaker for 15-30 min. Absorbance was read at 590 nm with a reference filter at 620 nm. Table Table S3. Expression changes in genes associated with degrees of melanoma malignancy. The Reverse FAM111B CAAATCCAGAGCGGCGGGCA ACAGGTGTGTCAGCATGTGTCTGC HIST1H2BB TTCTCGCCTGGCTCACTACA GCACAGCCGTCTGAATCTCC UHRF1 AGACAAGCTGTTCGCGGCGA TGGCCGTCCTCCATCTGTTTGC CCNE2 GGTAGCTGGTCTGGCGAGGT ATTCCGTCTGGCTGGGCTGG CCNA2 GTCACCACATACTATGGACATG AAGTTTTCCTCTCAGCACTGAC DEPDC1 TGCCTAGCAAATTGGCCAAGAAGCA ACTGTGATGTAGCCACAAACAACCA XRCC2 GAATGGCGTTGGTGGCGGGA AGTCGGGCAAGGAGCTCGGT BRCA2 GCAGACCCAGCTTACCTTGAGGGTT ACGCAACTTCCACACGGTTGTGA RAD51 GGCGGGAATTCTGAAAGCCGC TGCCATTACTCGGTCCGCAGCG BLM AGCACATTGTGTCAGTCAGTGGGG GTGGCCGTAAGAGCCATCACCG RPA2 AGTAGCCAGAGCGGCGCAGT GCTGGGCTCGGGCTCTTGATTTC TIMP3 AAAGGAGGGGCCCTTCGGCA GACGCGACCTGTCAGCAGGT TRIM38 TGCGAAGACGAGGGGCAGCT GGAGCTTTTCCTTGTAGCCCTGGC PRSS35 ACCAAACAAGCCTGGCAGGACA TGCCTCAAATGCGGGGCTGG MIR34A GCCAGCTGTGAGTGTTTCTTTGGC GCCCCACAACGTGCAGCACT TP53 TGCCTTCCGGGTCACTGCCAT CGGCAAGGGGGACAGAACGTT GAPDH CATGAGAAGTATGACAACAGCCT AGTCCTTCCACGATACCAAAGT
were treated with 20 M C646 or DMSO for 5 days. Media and compounds were replaced every other day. Cells were collected on day 3 and day 5 for flow cytometry analysis. Approximately 10 5 cells per sample were stained with the annexin V/PI kit. Gating was done with cells stained with only one of the two fluorophores as well as un-stained cells. Early apoptotic cells were annexin V positive and PI negative. Late stage apoptotic cells, necrotic cells, or dead cells in general, were positive for both fluorophores.
PML immunofluorescence assay. WM35 and WM902B cells were plated on 2-well chamber slides at 1000 cells/well for the DMSO treatment and 4000 cells/well for the C646 treatment.The cells were treated with C646 (20 M) or DMSO 24 h after plating. The media and the compounds were replaced every day for 4 days. Afterwards, the cells were fixed in 4% paraformaldehyde (Electron Microscopy Sciences) in PBS for 10 min at 4°C. After washing with PBS briefly 3 times, the cells were permeabilized for 5 min at 4°C with 0.5% Triton X-100 in PBS. The cells were then washed in 3% bovine serum albumin (BSA) in PBS (BSA/PBS) and incubated with the anti-PML antibody (#sc-966, Santa Cruz Biotechnology) at 1:1000 in 3% BSA/PBS at 4°C for 4 h. Afterwards, the cells were washed 3 times in 3% BSA/PBS and incubated with the secondary antibody (1:2000 Alexa-Fluor 488 goat anti-rabbit) for 1 h at RT.
CCNA2 siRNA knockdown. WM35 cells were seeded in 6-well plates for 24 h before being transfected in duplicates. There were 4 conditions, including scrambled siRNA, siCCNA2 #1, siCCNA2 #2, and untransfected (medium only). Each transfection reaction was prepared as follows: (1) 7.5 l siRNA was mixed with 192.5 l OptiI-MEM Medium for 5 min at RT; (2) 5.0 l lipofectamine was mixed with 195.0 l OptiI-MEM Medium for 5 min at RT; (3) the two vials were combined and incubated for another 20 min at RT; (4) the siRNA/lipofectamine complex was then added to the cells drop wise. The total volume of the medium was 2 ml. The medium was changed 24 h after transfection and RNA was isolated after another 24 h using the RNeasy mini kit (#74104 Qiagen) according to the manufacturer's protocol.To assess the efficiency of the knockdown, 2 g of RNA was reverse transcribed with SuperScript™ III First-Strand Synthesis SuperMix (Invitrogen) according to the manufacturer's protocol. qPCR analysis of CCNA2 expression was performed using SybrGreen at an annealing temperature of 57 o C for 45 cycles. Gene expression values were determined with the Ct method using -actin as the internal control. The CCNA2 primers were as follows: (Forward) 5'-TGCATCTCTGGGCGTCTTTG-3'; (Reverse) 5'-ACCCGGCCAAAGAATAGTCG-3'.
Figure S1 .
S1Stage one of NCI-60 screen on tumor cell sensitivity to 100 M C646. For the methodology, refer to Shoemaker, 2006 and the NCI's Development Therapeutics Program website. The data are generated and graphed by the screening service. The numbers represent %cell growth relative to untreated control and to the cells seeded pre-treatment, which allows for detection of both growth inhibition and lethality. Negative numbers indicate cell death. The bar graph represents the difference between %growth of each cell line and the mean %growth of all cell lines. Note that the formula on the top of the graph is misprinted. It should state 'Growth Percent -Mean Growth Percent'.
Figure S2 .
S2Stage two of NCI-60 screen with 5 concentrations of C646. Each panel represents cell lines from one tumor type. Similar to stage one, each data point represents cell growth relative to control and starting number of cells.
Figure S3 .
S3Growth curve of the most C646-responsive cell line WM35 after p300 HAT inhibition as measured by the XTT assay. Cells were treated every other day with fresh media and compounds for 9 days.
Figure S4 .
S4Representative FACS histograms of cell cycle profiles after 24 h p300 HAT inhibition. Row 1, 2, 3, and 4 represent DMSO, 10 M C646, 20 M C646 and 20 M C37, respectively. Each column corresponds to one cell line. M1: G1 phase; M2: S phase; M3: G2/M phase. Note that there are 2 peaks after S phase in WM983B, which is most likely due to aneuploidy.
Figure S5 .
S5Summary of microarray results. (a) MvA plots of gene expression level comparison between C646 treated cells and DMSO treated cells at 6 and 24 h time points. Y-axes represent log2 difference of C646-DMSO for each gene. X-axes represent average of C646 and DMSO. Most genes do not show significant differences in expression and cluster near y=0. Data points above y=1 or under y=-1 indicate a greater than 2 fold (linear) change in expression. (b) Ontology analysis of genes upregulated by more than 2 fold at 24 h. The genes are grouped based on biological processes. p-values indicate the statistical significance of clustering. No statistically significant clustering was seen with the molecular functions GO database.
Figure S6 .
S6Western blots of additional growth regulatory proteins in WM35 cells after 24 h treatment with DMSO, C646 (10 and 20 M) or C37. Expression of these proteins was not significantly affected by C646.
Figure S7 .
S7Cyclin A expression in non-small cell lung cancers after 24 h treatment with C646 or control. (a) Western blot analysis of cyclin A protein expression in H23, H838 and H1395 cells. Lane 1-4 represent DMSO, 10 M C646, 20 M C646 and 20 M C37, respectively. (b) qRT-PCR analysis of cyclin A transcript level in the three cell lines. RQ: relative quantity normalized to DMSO; GAPDH is the internal gene control. N≥3.
Figure S8 .
S8Cyclin A expression in 6 glioblastoma cell lines after 24 h treatment with C646 or controls. Graphs represent qRT-PCRs of cyclin A transcript. Western blot data for each cell line are shown underneath each corresponding graph. Lanes match the 4 treatment conditions for PCR.Supplementary
three categories of genes are taken from Ryu et al. Expression trend indicates the level of gene expression change as cells progress from less to more malignant stages. Note that most of the genes in the top two categories are repressed by more than 2 fold after p300 HAT inhibition in WM35 cells, whereas there is no significant change in the bottom category of genes.
Figure S1
S1Figure S1
Figure S2
S2Figure S2
Figure S3
Figure S4
Figure S5
Table S1
S1Primers for real time quantitative PCR validation of microarray results.Gene
Forward
Table S2
S2Primers for real time quantitative PCR analysis of ChIP DNA.Gene
Forward
Reverse
BLM
GTGTGCCCACTTTCCCGGTTCA
CCAGGCGTCTGCACCCCATT
RPA2
AGGGGCTGGCAGAGCGGTAT
TGACGGCAGAAGTCGCGCAC
RAD51 CAAGCTCTCGAGCTCCCGTCTTG
GCCCGCGTCGACGTAACGTATC
XRCC2 ACCGGCGGCCTTGTTCCCATCT
TCGGGGCGATGTGTAGTGCCT
BRCA2 AGGAAACGGGCTCGGAGGTCT
TGGTAGTGGGCGGGGCTGTTA
CCNE2 GGAACCCATGACCCCCAGTCGT
GGTGAGGAGTTGCTGCGCGTA
CCNA2 GGAGAAACAAACTGGCTGGGGCG TCGCTCACTAGGTGGCTCAGCTT
TP53
TGAAAATACACGGAGCCGAGAGCC CGTGCTTTCCACGACGGTGACA
GAPDH AGGTCGGAGTCAACGGGTGAGT
CAGCTACCCTGCCCCCATACGA
Table S3
S3Expression changes in genes associated with degrees of melanoma malignancyGene
Expression trend
in melanoma
Fold Change in
WM35 after
C646
Activators of cell cycle progression, DNA
replication and repair
CDCA2
Up
-6.65
NCAPH
-5.61
NCAPG
-7.88
NCAPG2
-3.08
PBK
-4.50
NUSAP1
-5.76
BIRC5
-2.52
ESCO2
-3.60
HELLS
-4.93
MELK
-5.17
GINS1
-3.49
GINS4
-1.80
RAD54L
-3.34
TYMS
-2.00
DHFR
-2.45
Apoptosis resistance
BIRC5
Up
-2.52
Cellular adhesion and melanocyte differentiation
CDH3
Down
1.20
CDH1
-1.34
KIT
-1.03
PAX3
1.20
CITED1
1.34
TYR
-1.55
MLANA
1.32
MC1R
1.11
OCA2
1.25
| [
-0.02896738052368164,
0.03311799839138985,
-0.07367867231369019,
-0.11016080528497696,
-0.02178283780813217,
-0.04638407379388809,
-0.03754526376724243,
0.19106972217559814,
0.02061382494866848,
-0.034466370940208435,
-0.03506770730018616,
0.0039895074442029,
0.09014587104320526,
-0.000367... |
A History of Japanese Diaspora Archaeology
Douglas E Ross
A History of Japanese Diaspora Archaeology
10.1007/s10761-020-00566-4Accepted: 21 September 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020Japanese diaspora History of archaeology Method and theory
Japanese diaspora archaeology originated in the late 1960s but reports and publications did not appear until the 1980s. Early studies often included Japanese artifacts or sites within larger surveys, but by the 1990s and 2000s were the focus of targeted research. Most research has been undertaken in western North American and the Pacific Islands. Pre-War farms and work camps and World War II battlefields and incarceration centers emerged as primary topics of study, with the incarceration centers dominating the literature today. Research themes are diverse but emphasize material consumption, concepts of place, and patterns of cultural persistence and change.
educational fieldwork. These early reports can be divided into three major categories:
(1) targeted studies of Japanese sites or material culture, alone or part of larger surveys including non-Japanese sites; (2) mixed or multiethnic contexts that include a Japanese component; and (3) Chinese diaspora sites that contain Japanese artifacts. The frequency of research on Japanese diaspora sites increased in the 1990s, though most were geographically scattered one-off studies of limited scope and duration. Exceptions were sustained resource management initiatives at Manzanar and other World War II Japanese incarceration camps sponsored by the National Park Service beginning in the early 1990s. Archaeology of these former camps, accompanied in the 2000s by university-based research, has emerged as a distinct field apart from other time periods and site types. As such, a unified, self-conscious field of Japanese diaspora archaeology spanning the pre-through post-War eras is only a recent development and few studies have sought to cross these temporal boundaries. The following review of archaeological literature is divided into two main sections focused on the pre-War and World War II eras, followed by an overview of material culture studies in related disciplines and a discussion of disciplinary trends and prospects for future research. Emphasis is on the western United States and Canada and the Pacific Islands, which have been the focus of most research to date.
In British Columbia, resource management studies in the early 1990s documented remains of the late nineteenth-and early twentieth-century salmon canning industry in the fishing village of Steveston. One study explored remains of a Japanese boat builder's shop and girls' bunkhouse at Gulf of Georgian Cannery National Historic Site, revealing fishing gear and Japanese porcelain within the assemblage (Heitzmann 1994). Another study recovered Chinese, Japanese, and European Canadian artifacts in waterlogged deposits near former Japanese houses during archaeological monitoring at Britannia Shipyards National Historic Site (Deva Heritage Consulting 1994). Neither study included detailed analysis.
At North Pacific Cannery National Historic Site near Port Edward, British Columbia, archaeological survey identified remains of Japanese quarters and other domestic and industrial areas (Archer 2000). A similar survey at the early twentieth-century McLean Mill National Historic Site in Port Alberni on Vancouver Island uncovered remains of a possible artifact cache, refuse pit, and bathhouse associated with Japanese mill residents (Eldridge and Coates 1994). Artifacts comprised kitchen utensils and cookware, including Japanese ceramics, and were interpreted as intentionally cached prior to forced relocation during World War II because all objects were intact or broken in place. Nearby, turn-of-the-twentieth-century Chinese and Japanese cemeteries were documented between Courtenay and Cumberland in advance of highway construction, though no excavation was undertaken (Witt 1998).
In an academic study, Callaghan (2003) constructed computer simulation models to estimate the frequency and locations of Japanese wrecks along the British Columbia coast during the Tokugawa Era, and the potential that Asian artifacts found on Indigenous sites came from such wrecks. Keddie (2013) has also explored the frequency of Japanese shipwrecks along the BC coast as evidence for the influence of iron and other aspects of Asian culture on Indigenous societies of the Northwest Coast.
Among the earliest and most sustained research initiatives on pre-War Japanese sites is the ongoing Seymour Valley Archaeological Project, begun in 2000 by Bob Muckle of Capilano University in North Vancouver, British Columbia. Muckle has explored a series of Japanese logging camps in the Seymour Valley occupied primarily during the 1920s (Biddlecombe et al. 2003;Muckle 2001Muckle , 2002Muckle , 2004Muckle , 2009Muckle , 2010Muckle , 2013Muckle , 2017Muckle , 2020. It is a community-based project run as an undergraduate field school, combined with public tours, community lectures, elementary school programming, artifact displays, and media outreach. Fieldwork has uncovered thousands of artifacts of Japanese and European Canadian origin and a series of domestic and workrelated features from two Japanese-occupied camps that include remains of a Japanese bath (furo). Among research goals are reconstructing camp layout; investigating similarities and differences in demographics, residential patterns, and consumer habits between camps; examining diet, health, and gender roles; and exploring links to Japanese logging industrialist Eikichi Kagesu, who probably operated both camps.
The 1990s and early 2000s also saw developments in identification and dating of Japanese ceramics, with an emphasis on Japanese language terminology and the history of ceramic production in Japan, spearheaded by the work of Leland Bibb. In an unpublished early study, Bibb (1997) documented Japanese domestic and export wares of the Meiji and Taisho eras from the Home Avenue Dump in San Diego, focusing on form, decoration methods and motifs, and geographic origins. He also undertook the ceramic analysis for Schaefer and McCawley's (1999) report on Mugu Fish Camp and Costello et al.'s (2001) study of Japanese truck farmers, both discussed above. In the 2000s, Bibb presented brief reports on the history, technology, and decoration of Japanese stencil wares and the dating potential of the "Made in Japan" mark (Bibb 2001(Bibb , 2007.
In another pioneering study, Stenger (1993) sought to identify and date Asian porcelains (primarily Chinese) from pre-War sites in Oregon, Washington, Idaho, and Nevada using x-ray fluorescence (XRF) and optical emission spectroscopy. She described Japanese wares common on Chinese sites and proposed that some ceramics previously assumed to be Chinese are actually Japanese. In the late 1990s, Priscilla Wegars (1999), curator of the Asian American Comparative Collection at the University of Idaho, prepared a handout of Japanese artifacts commonly found on archaeological sites with standardized terminology, including beverage and pharmaceutical bottles, porcelain tableware, and coins.
Shortly after the turn of the millennium, Maniery (2004) offered a brief overview of archaeology on pre-War Chinese and Japanese sites in the western United States. She discussed decorative patterns on Japanese ceramics as reflections of Japanese beliefs and ways of life, the need for outreach with Japanese American organizations and Asian American studies scholars, challenges in interpreting the written record of immigrant life, and future trends that include public outreach and education.
2005-20
Initiation of Muckle's research project and publication of Maniery's review article, alongside foundational studies of World War II Japanese incarceration sites in the late 1990s discussed below, mark a watershed in the emergence of Japanese diaspora archaeology as a distinct field of study. At this time the quantity, quality, and geographic diversity of research on pre-War (and WWII era) sites increased noticeably, along with an increase in work on urban sites and a greater balance between resource management and academic studies.
Recent resource management studies in rural contexts include projects in Washington, Oregon, HawaiFi, the Northern Mariana Islands, and elsewhere in the Pacific. In Washington, Japanese and European American artifacts were recovered from a temporary Japanese lumber camp in Thurston County associated with the Union Lumber Company (Kaehler 2007). In a more substantial study, White and colleagues (White et al. 2009) presented results of excavations at the early twentieth-century Japanese Gulch Site, a community of lumber workers near Mukilteo, Washington. Artifacts were a mix of Japanese (including a wooden sandal [geta]) and European American goods, suggesting maintenance of traditional lifeways combined with participation in commercialized American culture as a matter of practicality and emphasizing the role of women as household consumers. In Oregon, a domestic refuse pit associated with a family of pre-War Japanese truck farm in Multnomah County was also subject to excavation, with ceramic analysis by Leland Bibb (Bibb 2013;Paraso et al. 2013). Results revealed the use of Japanese and European American products, with a preference for Japanese ceramics, along with emphasis on frugality. Overall, the assemblage appeared to reflect cultural preferences rather than socioeconomic status.
In HawaiFi, Berrigan et al. (2015) undertook excavations in a small domestic enclosure of stacked rocks near Kona on the Island of HawaiFi, used by Japanese coffee farmers during the first two decades of the twentieth century. Artifacts included a range of household items, including Japanese porcelain tableware and European American beverage bottles. Complementing earlier work in the Northern Mariana Islands (Dixon 2004), Dixon (2016) used ethnographic and ethnohistoric literature to explore whether archaeological remains of early twentieth-century farmsteads on Tinian represent a "transported landscape" from Okinawa, home of many immigrant farm laborers (see also Dixon et al., this volume). Dixon and Tuggle (2014) also edited an issue of the journal Pan-Japan on archaeology of the Japanese diaspora in Micronesia, including articles on ceramic consumption in Taiwan, the impact of Japanese industrial development on Palau, a Japanese lighthouse in the Caroline Islands, a Japanese railroad on Rota, and Japanese farmsteads on Tinian.
Although some earlier studies addressed urban sites, archaeological research on Japanese living in cities increased noticeably in the new millennium, primarily in a resource management context. Notable studies include sensitivity assessment, testing, and evaluation of a portion of San Jose's Japantown in conjunction with urban redevelopment (Anthropological Studies Center 2008;Massey et al. 2013). Work in nearby Oakland uncovered deposits associated with the Orimoto family, an Issei couple with Nisei children who occupied the parcel between 1935 and 1942, when they were forcibly removed to the Topaz incarceration center (Walker et al. 2012). Aside from Asian ceramics, the assemblage is dominated by European American artifacts. Authors interpreted the collection's low functional diversity as a marked contrast to European American Victorianism and middle-class consumer aspirations, and the Asian ceramics as indicative of a desire to maintain a sense of cultural identity. The European American artifacts, including toys, cutlery, and beauty products, testify to the family's dual Japanese American identity and desire to prepare their children for life in America.
In San Diego, Van Wormer (2009) reported on refuse deposits associated with Japanese households, and Zepeda-Herman and Price (2012) presented findings of archaeological monitoring that uncovered domestic refuse deposits dating ca. 1925-30 associated with a fishing camp occupied by Japanese families. These deposits were dominated by European American artifacts, plus smaller quantities of Japanese ceramics and glass pharmaceutical and beverage bottles, with ceramic analysis undertaken by Leland Bibb. Data were interpreted using an approach based in pattern recognition and consumerism, where material patterns are linked with socioeconomic factors. Analysis indicated retention of traditional foodways but comparison with other Chinese and Japanese sites revealed the fish camp assemblage had a lower proportion of Asian artifacts, suggesting greater adoption to American material culture and creation of a Japanese American identity.
In Seattle, Washington, Johnson (2017) discussed a carved stone found in the rear yard of an early twentieth-century residence, inscribed with a style of Japanese poetry known as senryu often used by immigrants to document experiences of discrimination and struggle. Also in Seattle, Valentino (2017) described remains of the Green Lake Gardens Company owned and operated by the Kumasaka family before and after the war, which served as a family business and a gathering point for the local Japanese community. Finally, in HawaiFi, domestic Japanese porcelain has turned up in early twentieth-century contexts on urban construction sites in Honolulu (e.g., Hammatt 2013a, b).
Starting late in the first decade of the millennium was an increase in academic studies of pre-War Japanese sites, beginning with Kraus-Friedberg's (2008 research on Chinese, Japanese, and Filipino plantation cemeteries in HawaiFi and Ross' (2009bRoss' ( , 2010Ross' ( , 2011Ross' ( , 2013Ross' ( , 2014Ross' ( , 2017a comparative study of Chinese and Japanese salmon cannery workers in British Columbia. Kraus-Friedberg applied a transnational framework to three ethnically segregated cemeteries at a former sugar plantation on the island of HawaiFi. For the Japanese cemetery (1890s-1970s), she explored how transnational politics influenced expressions of ethnic and national identity on gravestones of plantation workers, revealing that these expressions varied with fluctuations in Japan's status on the world stage. Workers' status abroad was affected by shifting fortunes of their homeland, and gravestone inscriptions indicate they were aware of these shifts and were strategic in their use of ethnic/national identity markers in local Hawaiian contexts.
Similarly, Ross developed an interpretive model rooted in transnationalism and diaspora in drawing comparisons between artifact assemblages from the Chinese bunkhouse and Japanese fishing camp at the Ewen Cannery . He argued that Asian diasporas employed household objects strategically in constructing and maintaining identities and in negotiating relationships with home and host societies. Diasporas are essentially imagined transnational communities whose collective identities are social constructions that draw on shared real-world experiences of the homeland and dispersal from it. They retain select elements of homeland culture, including imported goods and practices, resulting in simplified and generalized recreations of traditional behaviors, especially practices like drinking and dining that played a central role in creating and maintaining social bonds in the homeland. Ross' research included development of guides to identification and dating of Japanese ceramics and beverage bottles and a study of the fluid and transnational nature of artifact origins and identities, with his ceramic guide influenced by the work of Leland Bibb (Ross 2009a(Ross , 2012a. Aside from Campbell's ceramic research discussed below, there have been few recent archaeological studies of Japanese material culture besides Akin et al.'s (2016) guide to numismatic archaeology that includes a chapter on identification and uses of Asian coins in North America.
These scholarly studies were followed by academic research projects in HawaiFi, California, and Washington. Barna (2013) examined ethnogenesis in his study of late nineteenth-and early twentieth-century multiethnic ranches on the island of HawaiFi, whereby Japanese and other ethnic groups were incorporated into a uniquely hybrid local culture. Braje et al. (2014) explored remains of a multiethnic base camp on San Miguel Island in California's Channel Islands from the same time period, used variously by Island Chumash, Chinese abalone fishermen, Japanese pearl oyster divers, and European American seal hunters. A stone hearth and light artifact scatter that includes a Japanese porcelain bowl suggest the presence of Japanese fishermen. Riggs (2015) compared botanical remains from a family of Alsatian immigrants in Texas and a Japanese family in Oakland, California. She employed concepts of "homeplace" and "dwelling" to explore how each household used plants as potent symbols in creating liveable homes in contested space. For the Japanese Domoto family, their nursery business provided financial stability, a home, a sense of continuity with their homeland, and a symbol of their positive contributions to their community.
In Washington, there has been a flurry of academic literature in recent years, much of it published in a 2017 thematic issue of Archaeology in Washington, in which the resource management studies by Johnson and Valentino discussed above also appear. Carlson (2017, this volume) emphasized racialization and labor dynamics of company towns in his archaeological and archival study of Issei laborers' everyday practices in the sawmill town of Barneston, Washington. Aranyosi (2017) and Hartse (2017) presented interim reports on their historical and archaeological research at the Japanese sawmill town of Yama-Nagaya on Bainbridge Island (1880s-1920s), as part of the multidisciplinary Yama Project that included an academic field school (see also Hartse and Hannah, this volume). Themes emerging from this research include race, class, gender, and religion, within an overarching transnational framework. Campbell's (2017a, b, this volume) research presented an analysis and comparison of Japanese ceramics from previously excavated pre-War sites in Washington, Oregon, and California. Her goal was to develop a revised classification system for imported wares based on Japanese-language terms, expanding on studies by Ross and Bibb, to facilitate standardized documentation of Issei sites. In her analysis, Campbell (2019) focused on multiscalar connections at local, regional, and international scales; diversity and distinctions within and between communities; and overall patterning in the ceramics, including diagnostic attributes, dates and locations of manufacture, change over time, and links with stylistic trends in Japan. Campbell subsequently developed the online Historic Japanese Ceramic Comparative Collection hosted by the University of Idaho, containing photographs and diagnostic information on pre-War Japanese ceramics from her study. Another recent ceramic study relying heavily on Japanese language terminology is Danner's (2020) brief article on soba-choko, specialized sauce cups for dipping buckwheat noodles.
To date, there have been no substantial studies of Japanese sites in North America east of Wyoming and Colorado. However, Baker (2016) and Andrews and Schaller (2017) described a recent project at the Shofuso Japanese House and Garden in West Fairmont Park, Philadelphia, location of the 1876 Centennial International Exhibition. The Exhibition included a Japanese-built bazaar showcasing Japanese culture, later the site of a reconstructed Japanese house and garden. Grant-funded excavations in 2015 and 2016, organized by Shofuso staff and professional archaeologists as part of an exhibit and community outreach program, turned up artifacts associated with the 1876 Exhibition, including a figurine, teapot fragments, remains of a saké bottle, and ceramic roof tile.
Archaeology of the WWII Era
Targeted archaeological research on World War II era sites associated with the Japanese diaspora did not get underway until the late 1970s or early 1980s and was not common until the 2000s, but today comprises a large and diverse body of literature driven in large part by substantial government funding and active community involvement. Included here are studies of Japanese military sites in the Pacific, along with the more robust field of research on sites of Japanese and Japanese American wartime incarceration in the United States.
1970s to 90s
The 1980s and 1990s saw publication of the first substantial archaeological surveys of Japanese incarceration camps in the US plus reports on surveys of Japanese military installations on several Pacific Islands chains, including results of historian Colt Denfeld's pioneering battlefield surveys in the Federated States of Micronesia, the Commonwealth of the Northern Mariana Islands, and the Marshall Islands in the 1970s and 80s (Mushynsky et al. 2018:205;Price and Knecht 2012:16). King and Parker (1984) described results of the Tonaachaw Archaeological Project on Moen (now Weno) Island in Chuuk State of the Federated States of Micronesia in the late 1970s and early 1980s. As part of this combined academic and salvage archaeology project artifacts were recovered from a latrine used by the Japanese military in the early 1940s, mostly bottles for Japanese beer and other beverages. This discovery raised questions about the origin of alcohol use and abuse on the island.
Between the late 1970s and mid-1980s, a series of research projects were undertaken in the Republic of Palau in Micronesia and on the Island of Saipan in the Northern Mariana Islands. Butler and Snyder (1991) reported on systematic documentation of Japanese military sites in Palau, emphasizing their significance for research on military adaptations and their value in promoting Japanese tourism and preserving remains of a significant period in the nation's history. Russell and Fleming (1991) documented excavation by the Commonwealth Division of Historic Preservation of a mass grave on Saipan, containing remains of Japanese military casualties discovered during construction on private property. The grave was linked to a famous Japanese suicide attack on American forces in 1944 and focus of the study was on questions related to the battle. This study was significant in light of the activities of bone-collecting excursions from Japan that had destroyed similar sites without careful excavation and study, and set a precedent for future treatment of War-era sites in the Pacific. Finally, Adams (1997) presented results of a 1989 survey of the Japanese airbase on Taroa in the Republic of the Marshall Islands. Results show that pre-War concrete structures from the late 1930s were superior in quality to wartime construction. Adams noted that preservation of this World War II heritage depends on perceived economic benefits from tourism because it has little direct interest and relevance to islanders.
The first archaeological study of a Japanese incarceration site in North America was a resource management survey undertaken in 1983 on the Gila River Indian Reservation in Arizona, which identified remains of the former Gila River War Relocation Center as potentially eligible for the NRHP (Effland and Green 1983). A 1987 survey and evaluation conducted as part of an agricultural development project proposed by the Bureau of Reclamation documented artifacts and features associated with Butte Camp, which, along with nearby Canal Camp, comprised the Relocation Center (Sullivan et al. 1987). This was the first study to document two defining features of incarceration camp archaeology: Japanese ceramics and Japanese names inscribed in structural cement. Additional data were collected at Butte Camp in 1988 to mitigate project impacts, including supplementary survey, artifact collection, and preliminary analysis (Sawyer-Lang 1988), followed in 1993 by additional archival research, oral histories, and detailed analysis of a sample of artifacts (Tamir et al. 1993a, b). Artifacts were discussed in oral interviews for potential information on function and cultural associations, while historical research sought information on the source of goods used in the camp and interactions between incarcerees and local Akimel O'otham people. Analysis addressed questions on social organization, economy, subsistence, and living conditions, with authors concluding that the assemblage is best described as "ordinary." A small resource management survey was later conducted at the edge of Butte Camp in 2010 (Wright 2010).
Other pioneering resource management inventories and assessments were undertaken in the 1980s and early 1990s at Heart Mountain Relocation Center in Wyoming (Farrell 2015;Gorman 1985). The most substantial early relocation center survey, however, was undertaken between 1993 and 1995 by the National Park Service at Manzanar, designated a California Historic Landmark in 1973 and a National Historic Site (NHS) in 1992 (Burton 1996). Focus was on recording and evaluating all archaeological resources associated with the relocation center, along with other precontact and historic occupations in and adjacent to the NHS. The initial goal was to document the condition of the site and identify data valuable for preservation and public interpretation. The three-volume report contains detailed descriptions of all documented sites and features and numerous appendices, including hundreds of War-era inscriptions, in-depth artifact reports, archival maps, and architectural drawings.
Research themes identified for Manzanar include confinement, ethnicity, resistance, and daily life. Authors emphasized that, despite being imprisoned because of their ethnic/national origins, incarcerees continued to express their Japanese identities through things like ceramics, saké bottles, gaming pieces, inscriptions, and landscaped gardens and ponds, while also adopting a range of European American goods and practices. They proposed that Americanization was generational, and, in contrast to researchers at Gila River, argued that material patterns at Manzanar were not "ordinary" but exhibited extensive influence of confinement, ethnicity, and war-related shortages, as indicated by low artifact diversity, pro-Japanese/anti-US graffiti, and smuggled alcohol. Additional War-era features were documented during subsequent resource management studies in the late 1990s and early 2000s, including investigations at the relocation center cemetery, administration block, and entrance (Burton 2005a;Burton et al. 1998. The administrative block offered comparative data for material from Japanese residential blocks, including distinct artifact patterns and landscape features that spoke to issues of individual expression vs administrative control. Overall, archaeology at Manzanar contributed not only to research and public interpretation, but also to expanding the boundaries of the National Historic Site.
Following initial work at Manzanar, the National Park Service compiled a wideranging overview of the tangible remains of Japanese incarceration in the US, called Confinement and Ethnicity, focusing on War Relocation Authority centers but including facilities run by the Department of Justice and US Army (Burton et al. 1999). The goal of this massive study was to generate information for the Japanese American National Historic Landmark Theme Study authorized by the same Act of Congress that established Manzanar as a National Historic Site. A related goal was to identify additional sites warranting National Landmark status or listing on the NRHP. Research included archival records, interviews with former incarcerees, and field visits to each site to photodocument surviving architecture, archaeological features, and artifacts. Researchers noted that there were fewer archaeological correlates of Japanese ethnicity at Tule Lake and other segregation/isolation centers used for incarcerees with allegedly greater Japanese loyalties, perhaps reflecting tighter security. They also drew preliminary comparisons between sites, observing more substantial landscape features like ponds and walkways at Manzanar and Gila River than elsewhere, perhaps reflecting a greater degree of permanence or resistance.
2000-14
During the first decade and a half of the twentieth century, a steady stream of reports and publications appeared on World War II-era Japanese battlefields and fortifications in the Pacific, only a sample of which are discussed here. Christiansen (2002) offered an overview of four former Japanese military bases on the Marshall Islands subject to resource management surveys in the 1990s, assessing condition, ongoing threats from deterioration and looting, and issues surrounding continued preservation. Bulgrin (2005) analyzed spatial distribution of military artifacts at a pre-War Japanese residential complex for agricultural workers on Saipan to address combat conditions and techniques during the US invasion in 1944, as part of a resource management study undertaken in advance of private development. Taborosi and Jenson (2002) summarized the use of natural and artificial caves as defensive fortifications by Japanese forces on Guam in Micronesia and in the Commonwealth of the Northern Mariana Islands. Such caves were also used as wartime refuges by civilians and hiding places by post-War Japanese stragglers. A range of artifacts have been documented in such caves, including military gear, small arms, tools, clothing, ceramic and metal tableware, culinary implements, glass bottles, and various personal items. Dixon et al. (2012) presented a more detailed discussion of limestone caves, rock shelters, and other refuges used by Japanese stragglers on Guam following the 1944 US invasion. Resource management surveys on behalf of the US Navy in 2002 showed that such stragglers, the last of whom was captured in 1972, made extensive use of American-made (and some Japanese) items from military dumps for daily survival. Alongside a similar range of artifacts as those described by Taborosi and Jenson (2002), researchers also documented defensive walls and platforms for cooking and sleeping.
In a pair of innovative articles, Knecht (2012, 2013) of the University of Aberdeen offered an in-depth discussion of their survey of Japanese-occupied Peleliu in the Republic of Palau, invaded by the US in 1944. Post-War neglect of this battle, accompanied by limited subsequent development and a small modern population, has made this the best-preserved battlefield in the Pacific, comprising structures, vehicles, equipment, ammunition, defensive and offensive positions, and hundreds of fortified caves. Funded by the National Park Service, and in collaboration with the Palau Bureau of Arts and Culture, objectives were to inventory the battlefield, assess its preservation, document oral histories of indigenous Palauans, promote demining of the island, and assist Palau in managing its battlefield heritage. Survey was undertaken with assistance of Indigenous archaeologists from Palau and other parts of Micronesia and included documentation of traditional cultural resources, with the long-term goal of opening the battlefield to visitors and maximizing the reflective and commemorative potential of the landscape free from artificial military triumphalism.
The preservation and sheer quantity of material on Peleliu offers a unique potential for conveying the raw experiences and emotions of participants, allowing for development of a social archaeology of the conflict free from traditional concerns with troop movements, equipment, and military strategy. This study, thus, sought to present a new kind of intimate, multicultural battlefield archaeology and redress historical biases by focusing on marginalized combatants and forced laborers from Korea, Okinawa, Palau, and other Pacific Islands, alongside Asian, Hispanic, and Native Americans.
Researchers placed emphasis on collaborating with, and seeking permission from, traditional island chiefs and incorporating local perspectives on the imported alien conflict. A key element was discussion of ongoing physical memorialization of the war on Peleliu from both Japanese and American perspectives.
Three Farewells to Manzanar and Confinement and Ethnicity marked a watershed in the archaeology of Japanese wartime confinement and cemented the National Park Service, especially Jeff Burton and Mary Farrell, as preeminent leaders in the field. In the early 2000s there was an explosion of archaeological research on incarceration sites in the US, in both a resource management and academic context, that has continued to this day and dwarfs studies on pre-War sites by a large margin.
Pioneering work at Manzanar in the 1990s resulted in the first graduate thesis on the archaeology of Japanese incarceration. Nicole Branton (2000Branton ( , 2004Branton ( , 2009) completed her MA and PhD research on Manzanar, focusing on everyday resistance through Japanese ceramics from the camp landfill. She drew on the concept of "eventscape," a type of cultural landscape where people from different places, times, and social contexts are linked via their participation in related events (Camp, this volume). Through this lens, Branton examined how incarcerees manipulated their material environments to create "home places" within relocation centers. For example, women prepared traditional meals inside barracks using Japanese ceramics to mitigate disruptions to family cohesion caused by communal mess halls. Branton also gathered oral histories from so-called "Tucsonians" and their families, Resisters of Conscience who refused the World War II draft and were imprisoned at the Catalina Federal Honor Camp near Tucson, Arizona (Branton 2004). Remains of this former prison were deemed ineligible for the NRHP in the 1980s. However, its status has been reconsidered following formal recognition of the Tucsonians and discovery that Gordon Hirabayashi, famous for resisting Japanese incarceration, was imprisoned there during the War (Farrell and Burton 2011). Research by archaeologists on the history of the prison played a pivotal role in bringing these connections to light and developing on-site commemoration of Japanese Americans imprisoned there.
Following their Manzanar and Confinement and Ethnicity projects, Burton, Farrell, and collagues at the National Park Service undertook archaeological investigations at Minidoka National Historic Site in Idaho, then known as Minidoka Internment National Monument (Burton 2005b;Burton et al. 2003). Designation of Minidoka as a National Monument in 2001 came directly from recommendations contained in Confinement and Ethnicity, which also served as the basis for subsequent archaeology at Tule Lake (Burton and Farrell 2005), Topaz (Ellis 2002), Amache, and other incarceration sites. Goals and methods at Minidoka paralleled Manzanar, with emphasis on documentation, evaluation, preservation, and public interpretation of surviving structures, features, and artifacts, including the camp landfill that then lay outside the monument. Recommendations included acquisition of additional land to encompass all War-era resources. One unique study at Minidoka targeted the post-War John Herrmann Farm, part of a homesteading initiative that granted former relocation center land to veterans and included recycling of relocation center buildings as part of the next stage of settlement (Burton and Farrell 2006). Burton and Farrell's work at Minidoka was succeeded by resource management inventories and evaluations at Poston Relocation Center on the Colorado Indian Reservation in Arizona on behalf of the National Park Service, and at a series of Japanese American incarceration sites in HawaiFi (Burton 2006;Farrell 2007, 2008). Work in HawaiFi was undertaken in collaboration with the Japanese Cultural Center of HawaiFi and involved reconnaissance at eight separate sites on the islands of HawaiFi, KauaFi, Maui, and OFahu. They identified the former Honouliuli Internment Camp on OFahu, which housed Japanese internees and non-Japanese POWs, as having the greatest archaeological and educational potential and undertook a separate survey there in 2008. Additional surveys were competed between 2009 and 2011, with support by the National Park Service and the University of HawaiFi-West OFahu (Burton et al. 2014b). Documented features include buildings, foundations, septic tanks and cesspools, roads, fence lines, artifact scatters, inscriptions, and other aspects of the World War II landscape. Based on this research, Honouliuli was listed on the NRHP in 2012 and designated a National Historic Site in 2019.
Contemporary with work at Minidoka, Farrell and Burton (2004) published an overview of archaeological research on Japanese American relocation sites as a companion to Maniery's (2004) discussion of pre-War sites. It summarized the history of incarceration and their work at Manzanar, Minidoka, and elsewhere, and includes a discussion on the reciprocal relationship between archaeology and oral history. Oral history plays a key role in guiding archaeological research, but public outreach about archaeology can also lead to additional oral accounts. Complementing this overview, Casella (2007) situated the archaeology of Japanese incarceration within the broader context of archaeological studies of institutional confinement. Reviewing the archaeological literature, she highlighted the role of ceramics, landscape features, and personalized inscriptions in strategic maintenance of collective Japanese identity, but also its fusion with mainstream American culture. For Casella (2007:136), such sites "illuminate not only the transcripts of collective resistance, but the personal coping strategies and inmate solidarity practices that often flourish in places of confinement." She emphasized the strong emotional responses confinement sites elicit from former incarcerees and their descendants as places of personal and collective commemoration, but also how they focus attention on the ambiguous relationship between the American state and its multicultural society and contribute to public debates about institutional confinement, citizenship, and civil rights.
By far the longest-running university-based research project at a Japanese incarceration site was begun at Colorado's Granada War Relocation Center (aka Camp Amache) in the mid-2000s by Bonnie Clark from the University of Denver (Clark and Shew, this volume). Prior to Clark's involvement, the site was subject to a resource management survey in 2003 sponsored by a historic preservation grant and funds provided by former incarcerees and their descendants (Carillo and Killam 2004;Clark 2017c). The study concluded that Amache retained superb archaeological integrity and it was designated a National Historic Landmark in 2006. This initial survey produced the first graduate thesis on the archaeology of Amache, a study of saké acquisition and consumption at the camp based on archaeological data and interviews with former incarcerees (Slaughter 2006(Slaughter , 2013. Slaughter interpreted illegal saké consumption as an act of resistance to camp rules and a means of maintaining collective identity, given its traditional role in Japanese ritual and social life.
Clark conceived her research at Amache as a long-term, community-based archaeology and heritage project involving fieldwork, museum studies, and community outreach. She undertook her first biennial archaeological field school in 2008, involving undergraduate and graduate students, with a strong focus on gardening, landscaping, and artifact modification and reuse. The first graduate thesis arising from this project was Skiles' study of Japanese ceramics based on her 2006 survey of camp dumps and barracks blocks (Skiles 2008;Skiles and Clark 2010). She concluded that Japanese ceramics were carried or shipped to the site by incarcerees to combat the disruptive and isolating nature of camp life and maintain pre-War ethnic identities, family bonds, and domestic routines, including use of traditional foods and cooking methods.
Effects of incarceration on community and family structure at Amache were further explored by Shew and Kamp-Whittaker through archaeology, oral history, and archival research (Kamp-Whittaker 2010; Shew 2010; Shew and Kamp-Whittaker 2013). They confirmed cooking within barracks was a common means of maintaining cultural traditions and family unity but noted that consumption patterns included both Japanese ceramics and colorful Fiesta Ware, indicating influences from mainstream European American society. Shew, granddaughter of a former incarceree, focused on persistence and change in identities of Japanese American women in public and private contexts. Kamp-Whittaker addressed factors influencing the socialization of children, including social landscapes where children played and decisions by adults and children regarding appropriate/popular toys for different age and gender groups. As with dining, consumption patterns by (or on behalf of) Japanese women and children were influenced by both Japanese and American consumer culture.
In 2010 Stacey Camp, then at the University of Idaho, initiated research at the Kooskia Internment Camp in rural Idaho, directing archaeological field schools in 2010 and 2013. Kooskia was a Department of Justice incarceration facility occupied by over 200 Japanese and Japanese American men during the War, paid as highway construction workers (Wegars 2010). Research emphasized how racialized minorities used material culture to communicate their feelings about citizenship and on the materiality of masculinity and gender ideology under conditions of isolation and imprisonment (Camp 2011(Camp , 2013. Objects like internee art, along with Japanese gaming pieces, pharmaceuticals, and ceramics testify to resistance and ongoing cultural ties to Japan, but identities of these men also involved more complex links to Japan and the United States. Camp has also emphasized comparative research and standardized recording practices between incarceration sites (Camp, this volume).
Alongside research on an increasing number of incarceration camps, work continued at Manzanar, combining resource management needs with scholarly research. Burton and Farrell (2013) studied graffiti at Manzanar emphasizing themes of individuality, resistance, identity, and change in camp attitudes among the over 280 incarceree inscriptions in concrete. Burton and colleagues also reported on their study of the Arai family fishpond in conjunction with its restoration (Burton et al. 2014a). Additionally, Burton and Farrell presented an overview of Manzanar's Japanese gardens, emphasizing their unique number, size, and complexity, in part a product of the number of gardeners incarcerated there (Burton 2013;Burton and Farrell 2014). Gardens served as reminders of home, improved morale, and reduced the harsh dust and sand. They cautioned, however, against interpreting these gardens solely as a product of Japanese design principles, noting that few gardeners had formal training and many aspects of garden design were adaptations to local camp environs.
In contrast, Beckwith (2013) interpreted Manzanar's ornamental gardens as an explicit product of Japanese culture and design, providing incarcerees with a sense of community and place in a time of extreme hardship and societal rejection. Ng (2014) expanded on this idea, using archaeological data, documentary sources, and oral histories to explore how Japanese Americans at Manzanar constructed landscape features like ornamental gardens and subfloor basements below residential barracks to transform their austere accommodations into a place they could consider "home." Surprisingly, no substantial archaeological studies have been undertaken on War-era Japanese incarceration sites in Canada. However, associated archaeological remains have been occasionally documented during resource management surveys. As part of a redevelopment project at the Bridge River Townsite west of Lillooet, British Coumbia, Gray (2009) reported on remains of War-era stone retaining walls. Japanese Canadians were relocated to the nearly abandoned 1920s hydroelectric model townsite in 1942, and these walls were probably part of an effort by incarcerees to cultivate the landscape of the self-supporting wartime settlement.
2015-20
In the past half-decade, archaeological research and publishing on World War II era sites has continued at a prodigious pace, with emphasis on Japanese incarceration facilities in the United States, mostly driven by work at Manzanar, Amache, Kooskia, and Gila River. Two literature reviews present a selective account of archaeological research to date, including Farrell's (2015) entry in the online Densho Encyclopedia and Ross' (2018) chapter in the National Park Service's Asian American Pacific Islander National Historic Landmarks Theme Study, the former focusing on incarceration camps and the latter including coverage of pre-War and War-era Chinese and Japanese sites. Petchey (2015) surveyed World War II Japanese defences on Watom Island in Papua New Guinea, including tunnel complexes, beach defences, gun emplacements, and associated artifacts including Japanese beer bottles, as part of a larger 2009 study focused on the island's ancient Lapita occupation. His aim was to compare Watom with Japanese defences on other islands and to frame the Japanese occupation as one wave of settlement in a long archaeological history. Mushynsky and colleagues studied caves and tunnels on Saipan, known collectively as karst defences (Mushynsky et al. 2018;Mushynsky 2019). Emphasis was on construction and use of these features, which were occupied by the Japanese military as command posts, combat positions, storage depots, and shelters, but also by civilians and US troops. Van der Riet (2018) completed her honors thesis in archaeology on the War-era Japanese occupation of Christmas Island, an Australian territory south of Indonesia. She documented and evaluated World War II heritage on the island for purposes of ongoing management and public interpretation. Cruz Berrocal and colleagues (2018) presented a historical archaeology of the longue durée for the island of Heping Dao, Thailand, spanning prehistoric times to the twentieth century. The Japanese colonial presence , dominated by World War II-era artifacts and features, marked a sharp discontinuity from prior occupations in terms of its substantial disturbance to the archaeological record and its reliance on imported goods and practices.
Burton, Farrell, and colleagues have continued their work at Manzanar, including completion of a Garden Management Plan (Burton 2015). This plan will guide restoration and rehabilitation of Manzanar's gardens, a priority in the site's General Management Plan. It will permit the public to view examples of the full range of garden types, including family barracks gardens, mess hall gardens, community parks, and administrative gardens, while stabilizing and maintaining the remaining gardens in their current state. They also reported on public archaeology at the Manzanar Chicken Ranch (Burton 2019), and at Block 15, which involved finding and restoring two Japanese pond gardens built by known individuals . Artifacts and features uncovered in Block 15 testify to ways incarcerees modified their environment and maintained their Japanese heritage, while also adopting a range of American material culture. Manzanar's ongoing public archaeology program is centered on collaboration with descendant and local communities, drawing on their knowledge and personal connections with the site (Burton 2017). Farrell and Burton have also completed additional documentation of Japanese incarceration sites in in HawaiFi, producing recommendations on preservation, interpretation, commemoration, and research, including a summary of archaeological investigations at Honouliuli between 2006 and 2017 (Farrell 2017a, b).
Clark has directed field schools at Camp Amache every other year since 2008, except for 2020 because of the coronavirus pandemic. Fieldwork, involving undergraduate and graduate students and community volunteers, is combined with work in the Amache Preservation Society Museum in Granada and designed in consultation with survivors, descendants, and other community members (Clark 2017c;Clark and Shew, this volume). Research focus has been on Japanese gardens and landscaping, including adaptation of cultivation methods to the environment and translation of Japanese American values and aesthetics to circumstances of upheaval and shortage (Clark 2017a(Clark , b, 2020. Methods include pedestrian survey of barracks blocks, test excavations, soil chemistry, and botanical analysis, combined with archival research and oral history. Results showed that incarcerees transformed the landscape as part of an investment in a sense of place, with gardens reflecting Japanese traditions and American landscape trends. Barracks blocks became distinct neighborhoods with unique identities, reflected in landscape features, artifact patterning, and social network data (Kamp-Whittaker and Clark 2019a, b; Kamp-Whittaker, this volume). There is a strong emphasis on public engagement, including open houses and student-designed museum exhibits that promote dialogue, critical reflection, multivocality, and community interpretation (Clark 2018;Clark and Amati 2019).
Data from Amache have served as a basis for graduate student research, including four theses completed between 2006 and 2010 (discussed above) and four completed in 2015. Driver (2015) investigated saké production and consumption in the context of its traditional importance in Japanese life, with emphasis on how incarcerees maintained aspects of everyday life in ways that were not about overt resistance. Garrison (2015) focused on Japanese entryway gardens, revealing Japanese design principles, cultivation of local and exotic plants, use of scavenged and repurposed materials, and soil amendment, concluding that landscaping played an important role in perseverance and maintenance of collective ethnic identity under institutional confinement. Starke (2015) uncovered evidence for traditional Japanese practices at Amache, including sumo wrestling, use of bath houses (furo), dramatic performances, and festivals like Obon. These practices aided in bridging generational gaps and were accompanied by elements of mainstream American culture, suggesting incarcerees maintained aspects of Japanese heritage and incorporated non-traditional practices from their prior lives in America to create a unique incarceree consciousness. Swader (2015) examined evidence for modified material culture and adaptive reuse of utilitarian objects at Amache, alongside similar materials from Minidoka. His goal was to explore the relationship between structure and agency in everyday life in relocation centers, and how incarcerees achieved a degree of control over their environment.
The public and collaborative component of the Amache project is reflected in Fujita's (2018) experiences as a volunteer with his nephew in 2014. Fujita, a retired chemistry professor who was incarcerated at Amache, related how his involvement with the project helped him heal from the psychological wounds of incarceration and aided in piecing together aspects of his family history. In turn, he emphasized how stories of former incarcerees can serve to enhance and diversify the archaeological research. Camp (2016) has continued to advocate for comparative studies and pushing boundaries of traditional archaeological research. She has outlined methodological and interpretive challenges with studying incarceration centers (e.g., their size, brief occupation, lack of discrete household-specific deposits, and post-abandonment disturbance), and argued that archaeologists must think beyond traditional notions of the "site" to include multiple landscapes and communal deposits. She draws on Branton's (2004) use of "eventscape" to expand incarceration to include multiple camps and noncamp landscapes where little archaeological research has been undertaken to date. These landscapes include temporary holding facilities, places where detainees labored outside camps, and pre-and post-imprisonment Japanese American landscapes. According to Camp (2018a), a comparative archaeology of incarceration should include exploring material goods and practices between sites and groups of prisoners, differential access according to aspects of identity like socioeconomic status, and the lives of prison guards and officials. Ng and Camp (2015) explored the influence of institutional confinement on material consumption, drawing on data from Manzanar and Kooskia. Such research is crucial, they argued, because government propaganda and censorship masked the true material conditions of incarceration. In Camp's (2018a:601-602) words, "[a]rchaeology can extend a balm to the absences of silenced pasts, whether it is applied to the unintentional silence of prisoners too traumatized to relive their experiences through narrative or to the intentional silences manufactured by a government unwilling to reveal the truths of life behind barbed wire." Evidence from Manzanar shows that ornamental gardens and ponds served to create comfortable living areas, maintain family cohesion, and mitigate racial hostility, while artifacts from Kooskia testify to efforts at improving medical and dental care at the camp (Ng and Camp 2015). The authors concluded that material consumption permitted incarcerees to assert cultural identities, counteract government attempts at silencing, and fashion a sense of permanence in a temporary and volatile environment.
Undergraduate and graduate students have contributed to research at Kooskia. Fitz-Gerald (2015) investigated use of cold cream at the all-male camp in the context of theoretical approaches rooted in gender and masculinity. She concluded that gendered use of such products is not clear-cut, that hygiene practices among incarcerees were influenced by Japanese and American values, and that men may have used cold cream for shaving and general skin care or removing stage makeup following kabuki performances. Hosken and Tiede (2018) used archival and archaeological evidence of dental hygiene at Kooskia to demonstrate the importance of oral routines, including use of Japanese branded products. They adapted Silliman's (2014) use of the concepts of survivance and residence to argue that, rather than overt resistance, incarcerees used these routines and a petition for better resources under the Geneva Convention to forge a sense of home in the camp. Such practices also served to mitigate their circumstances of oppression and strive for public acceptance in American society, while maintaining a connection to their heritage. In a complementary study, Camp (2018b) explored evidence for visual and ocular health at the camp, including remains of safety goggles and eye medicine.
Coming full circle, Lau-Ozawa recently initiated research at the Gila River Incarceration Camp in Arizona, site of the first incarceration center survey in the early 1980s (Ozawa 2016;Lau-Ozawa 2019a, this volume). His Master's thesis focused on Japanese-built gardens at former incarcaeration camps, which he argued were "highly contested places with multiple meanings" (Ozawa 2016:7). Lau-Ozawa undertook systematic survey of garden ponds in residential and administrative blocks at Gila River, in conjunction with examination of archival sources, oral histories, and data from other camps, to develop a multiscalar analysis of garden construction, placement, design, and interactions at the individual, block, and camp levels. He concluded that gardens served as symbols of Japanese American resilience, tools for maintenance of individual and community identities, strategies for coping with conditions of incarceration, and a form of reterritorialization of camp spaces in an environment dedicated to Americanization. Lau-Ozawa (2019a) also explored ways incarceration heritage is memorialized materially at seven understudied detention facilities associated with Gila River. In doing so, he echoes Branton's (2004) and Camp's (2016) calls to view these physically separated locations as part of an interconnected eventscape.
Archaeology-Adjacent Research
In addition to explicitly archaeological studies, there is a body of archaeology-adjacent literature, produced by historians and other scholars in the social sciences and humanities, relevant to archaeological research in its focus on Japanese and Japanese American consumerism and material culture. The goal here is not to provide a comprehensive review of this literature, but to offer a sample of some of the most pertinent pre-War and World War II era studies as a launching pad for seeking out other archaeology-adjacent scholarship.
Regarding consumerism in Japan, Hanley's (1997) book Everyday Things in Premodern Japan explored a variety of everyday material goods and practices in Tokugawa and Meiji era Japan in conjunction with its move toward modernization, economic growth, and industrialization beginning in the late nineteenth century. More recently, Francks (2009aFrancks ( , b, 2015 presented an economic history of Japan from the eighteenth century to the present with focus on the consumer, including everyday consumption in urban and rural contexts, food and drink, clothing and household goods, and mass communication and transportation as Japan moved toward industrialization, Westernization, urbanization, and emergence of the middle class. An edited volume on related themes includes chapters on clothing and household goods, sugar, medicine, train travel, postal services, mail order retailing, and golf (Francks and Hunter 2012). Both volumes sought to draw connections and comparisons with patterns of consumerism in the West. While these volumes offer an overview of consumerism in Japan, studies like Alexander's (2013) Brewed in Japan focused on individual commodities, in this case the beer industry. Other recent commodity based research on Japan and the wider diaspora include studies on pottery (Miyachi 2007;Omori 2004), soy sauce (Amano 2004), sugar (Iijima 2019), coffee (Grinshpun 2014;Iijima 2018), trading companies (Oshima 2011(Oshima , 2013, and department stores (Fujioka 2014;Yamauchi 2014). This is just a sample of the burgeoning literature on Japanese domestic and transnational production, trade, consumerism, and material culture.
In North America, two important works are National Historic Landmarks Theme Studies sponsored by the US National Park Service, one focusing on Japanese American in World War II (Wyatt 2012) and the other on Asian Americans and Pacific Islanders more broadly (Odo 2018). The goals of both studies were to identify sites eligible for designation as National Historic Landmarks or listing on the NRHP and establish priorities for designation, and both contain a wealth of information on the material heritage of Japanese Americans. Narrower in scope, but equally important, Dubrow and Graves (2002) documented the Japanese American imprint on the urban and rural landscape and advocated for historic preservation through case studies of 10 places in Washington and California with significant Japanese American heritage values. These places include a mill town, dwelling, store, community hall, public bathhouse, Japanese language school, Buddhist temple, hospital and midwifery, urban neighborhood, and bowling alley.
For the pre-War era, Dubrow (2002Dubrow ( , 2005 explored Japanese American architecture in urban and rural contexts to explore patterns of cultural persistence and change and construction of Japanese American identity. Similarly, Lau (2013) focused on the role of the Japanese American home in aspirations of Japanese immigrants for national inclusion and middle-class respectability. Sueyoshi (2005) explored use of Western dress by Japanese immigrants as part of an ongoing struggle to gain acceptance as "Americans" in the face of entrenched racial categories that sought to define them as perpetual foreigners. In a complementary way, Imai (2010) showed how Japanese Americans in Hawai'i developed their own unique consumer culture during the interwar period as a strategy for claiming a place within the local "white" social hierarchy.
Emphasizing wartime incarceration, Horiuchi (2005) explored the architectural design and construction of camps and how incarcerees created their own built environments to address the inadequacies of these temporary government-designed cities. She and Pieris also compared spatial and material interpretive strategies at former incarceration facilities in the US and Australia, with an emphasis on gardens (Horiuchi and Pieris 2017). Dusselier (2008) examined incarceree art, focusing on how these objects helped reterritorialize foreign and hostile spaces, alleviate isolation and deprivation, maintain social identities and relationships, and contribute to physical and psychological survival. Similar conclusions were drawn by Tamura (2004) and Helphand (2006) in their studies of incarceration camp gardens, while Rozas-Krause (2018) analyzed the design, iconography, and motivations behind the memorialization of an assembly center in San Bruno, California.
Finally, spanning the pre-through post-War eras, Brown (1996) pondered the significance of a large collection of personal possessions stored in the basement of Seattle's Panama Hotel by Japanese Americans forcibly removed from the coast during the War but never retrieved by them. She drew concrete links between forfeiture of material things and loss of privileges associated with American freedom and citizenship, stolen from their former owners by a state that had reneged on the "American contract."
Research Trends and Future Directions
Archaeological research on the Japanese diaspora has expanded dramatically over the past several decades, especially in the last 20 years. Early studies were dominated by resource management initiatives with academic research rare until the start of the millennium. The first academic thesis on archaeology of Japanese incarceration was not completed until 2000 (Branton 2000) and the first thesis on the pre-War period not until 2008 (Kraus-Friedberg 2008). The first peer-reviewed journal article on the pre-War era was published in 1988 (Gardner et al. 1988), though no more appeared prior to the 2000s; the first such article on Japanese incarceration did not appear until 2016 (Camp 2016). Today the volume of literature in unpublished reports and in published books and journals is substantial, increasing at what seems like an exponential rate, and there is more of a balance between academic and resource management archaeology. Additionally, the quality of scholarship is equally high on both sides of the academic/CRM divide.
Documentation of Japanese-related deposits was often incidental to project objectives among many early studies, but today such remains are the focus of research. The transition from isolated, incidental studies to more focused, sustained, and selfconscious emphasis on the Japanese diaspora coincides with work by the National Park Service at Manzanar and on the Confinement and Ethnicity project, Muckle's field school on Japanese logging camps in British Columbia, and Bibb's efforts at applying Japanese language terminology to ceramic analysis beginning in the 1990s. To date, there have been university field schools at three incarceration centers (Amache, Kooskia, and Honouiuli) and three pre-War work camps (Seymour Valley, Lion Island, and Yama-Nagaya). In contrast, there has only been a single edited volume on the archaeology of the Japanese diaspora, covering the pre-War period in a single US state (Archaeology in Washington, Volume 17, 2017), and only a few literature reviews of limited scope (Farrell 2015;Farrell and Burton 2004;Maniery 2004;Ross 2018). Today, the literature on War-era sites vastly outweighs pre-War-era scholarship.
Methodologically, archaeological research on the Japanese diaspora has ranged from multi-sited and community level studies, to landscape studies and ones focused narrowly on the lives of households and individuals. Most have relied on traditional archaeological data, combined with data from archives and oral histories/memoirs, though some have used alternative methods like computer modelling (Callaghan 2003). At pre-War sites, attention has been primarily on household or community artifact assemblages, especially in laboring contexts, whereas work on War-era sites has placed considerable emphasis on structures and landscapes. Nevertheless, there are strong examples of pre-War landscape studies (e.g., Dixon 2004) and War-era artifact studies (various graduate theses on Amache). There are also excellent examples of communitybased research and collaboration for both time periods (e.g., Seymour Valley, Amache, Manzanar, Peleliu), though this is not yet the norm. A central insight arising from collaborative work at sites like Manzanar is the reciprocal relationship between archaeology and oral history.
Research topics are diverse, with strong emphasis on acquisition, consumption, and reuse of consumer goods, including factors affecting access to goods and how they inform aspects of identity, social interaction, and environmental adaptation. Special attention is paid to objects related to food and dining, but also recreational beverages, health and hygiene products, and toys, among others. For incarceration camps, pronounced attention is paid to Japanese gardens and other landscape features, whereas battlefield studies emphasize offensive and defensive military landscapes, though both also highlight personal items testifying to the experiences of individuals. Other topics include demographic patterns, social networks, cultural interaction, gender and age, class structure, resistance, entrepreneurship, pre-War caching, War-era military tactics and technology, intimate interactions, memorialization, collaboration, public interpretation, and disciplinary reflexivity. The primary objective of many studies is to support site management, preservation, and public interpretation.
There are no unified research themes or theoretical frameworks in Japanese diaspora archaeology. In fact, there is little in the way of generalized method and theory across the discipline, with most interpretation geared toward individual sites. Exceptions include Branton's (2004) concept of eventscape, Camp's (2011) advocacy for comparative approaches and standardized recording, Ross' (2013) transnational and diasporic framework, and comparative case studies by scholars like Kraus-Friedberg (2008) and Campbell (2017a). Valuable concepts like ethnogenesis, racialization, transnationalism, diaspora, gender, and sexuality have been adopted by some researchers, but to date have had limited impact on the field (but see Lau-Ozawa, this volume). As Ozawa (2016:24) argued, much archaeological research lacks appropriate consideration of recent historiography in Asian American studies, including use of Japanese language sources and frameworks rooted in globalization and trauma.
One common thread spanning numerous studies and time frames is an emphasis on patterns of cultural persistence and change, with many researchers concluding that members of the Japanese diaspora retained elements of traditional Japanese culture and identity while also adopting aspects of European American culture, a process often couched in terms of dual-identity formation or Americanization. This pattern is evident in unique combinations of Western-style and Japanese goods commonly documented on archaeological sites. At least two pre-War studies (Walker et al. 2012:171;Paraso et al. 2013:6.12) concluded that the Japanese diaspora artifact assemblages they analyzed are primarily a product of culture and ethnicity, rather than socioeconomic status or class, and according to Walker and colleagues are therefore difficult to compare with European American assemblages. This is a provocative claim that bears further scrutiny. Another increasingly popular approach, especially for incarceration camps, is the concept of "home" or "place" as it relates to efforts by incarcerees to maintain a sense of family or community cohesion to combat conditions of institutional confinement. This is part of a broader, though not always explicitly articulated, theme of structure versus agency pervading most archaeological research on the Japanese diaspora.
Practical challenges faced by researchers, especially (but not limited to) those working on former battlefields and incarceration camps, include expansive and multicomponent sites, mixed assemblages, and subsequent disturbance by cleanup, looting, and development. Horizontally extensive sites require complex research designs and years/decades of fieldwork and analysis to capture the nuances of the archaeological record, while those with mixed, disturbed, or multicomponent deposits constrain the ability of researchers to target specific households or groups. Few researchers have committed to long-term projects at a single site or location, exceptions being Bob Muckle in the Seymour Valley, Jeff Burton and Mary Farrell at Manzanar, and Bonnie Clark at Amache. In many cases, field methods are dictated by logistical challenges as much as by research agendas, for example Costello and Maniery's (1988) community-level analysis of mixed Chinese and Japanese deposits in Walnut Grove and emphasis at many incarceration sites on barracks blocks rather than massive landfill deposits that combine material from both incarcerees and administrators. Massey et al. (2013) noted that overlapping Chinese and Japanese occupations offer a distinct challenge in distinguishing site occupants, as both groups used goods imported from the other's homeland. While most archaeologists are cognizant that artifacts do not equal ethnicity, we still struggle with an often-unconscious reliance on "pots equal people" approaches to site identification.
Despite the increasing volume of research on the Japanese diaspora, there remain gaps in coverage, geographically, methodologically, and interpretively. There has been disproportionate emphasis on Japanese-style artifacts and features, as markers of cultural persistence, at the expense of other research avenues. For the pre-War era, urban sites remain underrepresented in the literature, as do sites outside western North America (but see Baxter and Chirinos Ogata and Saucedo-Segami, this volume). For the War-era, work is still needed at former incarceration center landfills and deposits associated explicitly with administrators and other non-Japanese camp staff, and greater attention is needed on assembly centers and other nodes in the evacuation/incarceration eventscape. While there are some sophisticated studies of Japanese battlefields in the Pacific, most research remains primarily descriptive and there is a need for more sophisticated theory-driven research. There has also been little work on Japanese cemeteries, churches/temples, and other community institutions (but see Goto, this volume), and very little engagement with archaeology and history in the Japanese homeland that could offer a baseline for understanding material patterns within the diaspora. Surprisingly, there remains virtually no archaeological research on post-War Japanese American sites and landscapes, and little formal dialogue between scholars working on pre-War and War-era sites.
In terms of material culture research, there have been some in-depth studies of Japanese ceramics, but other imported material culture remains largely unstudied, and methods like trace element analysis have barely been attempted. Curiously, despite attention given to food and dining, there have been few studies of faunal and botanical remains from Japanese diaspora sites. In addition, we still know little about international merchant networks and import-export firms like the Furuya Company of Seattle that transported goods from Japan throughout the diaspora. More broadly, despite increasing emphasis on collaborative, community-based research, there have been few (if any) truly multidisciplinary projects that involve community members and specialists in related fields as active and equal research partners. In fact, few studies engage in more than a limited way with other subdisciplines of archaeology and adjacent fields like Asian American studies. Exceptions include adoption of Dusselier's (2008) concept of reterritorialization by Ozawa (2016) and others, and Hosken and Tiede's (2018) engagement with Silliman's (2014) discussion of survivance and residence. Consequently, the influence of our research beyond our narrow subdiscipline remains limited. For example, few incarceration camp studies draw on the large volume of theoretical literature and comparative history and archaeology of institutional confinement in the spirit of Casella's (2007) work (but see Camp, this volume).
One research avenue that bears concrete attention is direct engagement and comparison with Chinese diaspora archaeology (Ross 2018;Voss and Allen 2008). Both fields have a similar history of research, address similar site types and research themes, and focus on immigrants and their descendants who experienced similar patterns of racist exclusion, job opportunities and constraints, adaptive strategies, and access to transnational networks. However, they also have important differences that could reward close comparative analysis, including the earlier arrival, larger size, and greater socio-economic networks of the Chinese diaspora, and the greater presence of women and families and more direct experience with government-sponsored Westernization within the Japanese diaspora.
While the number of research avenues yet to be explored seems vast, the accomplishments of Japanese diaspora archaeology over the past four decades and more are substantial, as the length of this review testifies. I suspect that in another 40 years a comprehensive literature review such as this will require an entire volume in its own right. The studies contained in this volume are just the beginning.
International Journal of Historical Archaeology (2021) 25:592-624
Marshall Islands Archaeology: The Japanese Airbase on Taroa Island, Republic of the Marshall Islands, 1937-1945: An Evaluation of the World War II Remains. W H Adams, US National Park Service; San FranciscoAdams, W. H. (ed.) (1997). Marshall Islands Archaeology: The Japanese Airbase on Taroa Island, Republic of the Marshall Islands, 1937-1945: An Evaluation of the World War II Remains. US National Park Service, San Francisco.
Numismatic Archaeology of North America: A Field Guide. Routledge. M H Akin, J C Bard, L Akin, New YorkAkin, M. H., Bard, J. C., and Akin, L. (2016). Numismatic Archaeology of North America: A Field Guide. Routledge, New York.
Brewed in Japan: The Evolution of the Japanese Beer Industry. J W Alexander, University of Hawaii PressHonoluluAlexander, J. W. (2013). Brewed in Japan: The Evolution of the Japanese Beer Industry. University of Hawaii Press, Honolulu.
Data Recovery and Treatment Plan for Historic Archaeological Resources on Bacon and Bouldin Islands. R Allen, L Mckee, San Joaquin and Contra Costa Counties. Past Forward IncRichmond, CAAllen, R. and McKee, L. (2002). Data Recovery and Treatment Plan for Historic Archaeological Resources on Bacon and Bouldin Islands, San Joaquin and Contra Costa Counties. Past Forward Inc., Richmond, CA.
A comparative business history of the soy sauce industry. M Amano, Japanese Research in Business History. 21Amano, M. (2004). A comparative business history of the soy sauce industry. Japanese Research in Business History 21: 12-31.
Japan in 1876 Philadelphia: Japanese house archaeology and educational outreach program. K Andrews, N Schaller, Public Garden Magazine. 321Andrews, K. and Schaller N. (2017). Japan in 1876 Philadelphia: Japanese house archaeology and educational outreach program. Public Garden Magazine 32(1): 6-9.
Historical Context and Archaeological Survey Report: Heinlenville/ San José Corporation Yard Archaeological Project. Anthropological Studies Center. Anthropological Studies CenterSonoma State UniversityAnthropological Studies Center. (2008). Historical Context and Archaeological Survey Report: Heinlenville/ San José Corporation Yard Archaeological Project, San José, California. Anthropological Studies Center, Sonoma State University, Rohnert Park, CA.
The Yama Project: a multidisciplinary analysis of a historic transnational Japanese village on Bainbridge Island. E F Aranyosi, Archaeology in Washington. 17Aranyosi, E. F. (2017). The Yama Project: a multidisciplinary analysis of a historic transnational Japanese village on Bainbridge Island. Archaeology in Washington 17: 1-15.
North Pacific Cannery Village Museum: Archaeological Resource Inventory. D J W Archer, Parks Canada, Calgary, ABArcher, D. J. W. (2000). North Pacific Cannery Village Museum: Archaeological Resource Inventory. Parks Canada, Calgary, AB.
Archaeological dig at Shofuso unearths remnants of long-forgotten Japanese bazaar. Philly Voice. B Baker, Baker, B. (2016). Archaeological dig at Shofuso unearths remnants of long-forgotten Japanese bazaar. Philly Voice, April 11, 2016, https://www.phillyvoice.com/archaeological-dig-shofuso-uncovers-long-forgotten- japanese-bazaar-fairmount-park/, accessed August, 2020.
J C Bard, C Busby, Cultural Resources Report on the Wade Ranch, Orchard Properties, Inc. Parcels 611 and 612. San Jose, California; Hayward, CABasin Research Associates, IncBard, J. C. and Busby, C. (1985). Cultural Resources Report on the Wade Ranch, Orchard Properties, Inc. Parcels 611 and 612 San Jose, California. Basin Research Associates, Inc., Hayward, CA.
Ethnogenesis of the Hawaiian Ranching Community: An Historical Archaeology of Tradition, Transnationalism, and Pili. B T Barna, RenoUniversity of NevadaPh.D. dissertationBarna, B. T. (2013). Ethnogenesis of the Hawaiian Ranching Community: An Historical Archaeology of Tradition, Transnationalism, and Pili. Ph.D. dissertation, University of Nevada, Reno.
Japanese-Style ornamental community gardens at Manzanar Relocation Center. R J Beckwith, Prisoners of War: Archaeology, Memory, and Heritage of 19th-and 20th-Century Mass Internment. Mytum, H. and Carr, G.New YorkSpringerBeckwith, R. J. (2013). Japanese-Style ornamental community gardens at Manzanar Relocation Center. In Mytum, H. and Carr, G. (eds.), Prisoners of War: Archaeology, Memory, and Heritage of 19th-and 20th- Century Mass Internment. Springer, New York, pp. 271-284.
Archaeological Data Recovery, Kahului to Keauhou Parkway, Kahului 1-2, Puapua'a 1-2, Holualoa 1-4, Kaumalumalu, Pahoehoe 1-4, La'aloa 1-2, Kapala'alaea 1-2, Kahalu'u and Keauhou Ahupua'a. D Berrigan, A Haun, D Henry, Haun & Associates. Berrigan, D., Haun, and A. Henry, D. (2015). Archaeological Data Recovery, Kahului to Keauhou Parkway, Kahului 1-2, Puapua'a 1-2, Holualoa 1-4, Kaumalumalu, Pahoehoe 1-4, La'aloa 1-2, Kapala'alaea 1-2, Kahalu'u and Keauhou Ahupua'a, North Kona District, Island of Hawai'i. Haun & Associates, Kailua- Kona, HI.
Unpublished manuscript in possession of the author. L E Bibb, San Diego, CaliforniaJapanese Ceramics from the Home Avenue DumpBibb, L. E. (1997). Japanese Ceramics from the Home Avenue Dump, San Diego, California. Unpublished manuscript in possession of the author, corrected and revised 2006.
Japanese stencilwares of the Meiji and Taisho eras. L E Bibb, Supplement. 181Asian American Comparative Collection NewsletterBibb, L. E. (2001). Japanese stencilwares of the Meiji and Taisho eras. Asian American Comparative Collection Newsletter, Supplement 18(1): 5-6.
Pre-1921 use of mark "Made in Japan. L E Bibb, Asian American Comparative Collection Newsletter, Supplement. 242Bibb, L. E. (2007). Pre-1921 use of mark "Made in Japan." Asian American Comparative Collection Newsletter, Supplement 24(2): 5-6.
Japanese Ceramics from a Japanese-American Farmstead in Gresham. L E Bibb, Oregon. Willamette Cultural Resources Associates, Ltd. Bibb, L. E. (2013). Japanese Ceramics from a Japanese-American Farmstead in Gresham, Oregon. Willamette Cultural Resources Associates, Ltd., Portland, OR.
Community archaeology in the Seymour Valley, British Columbia: education, research, and heritage management. K Biddlecombe, M B Sayre, C Mclaughlin, Teaching Anthropology: SACC Notes. 101Biddlecombe, K., Sayre, M. B., and McLaughlin, C. (2003). Community archaeology in the Seymour Valley, British Columbia: education, research, and heritage management. Teaching Anthropology: SACC Notes 10(1): 17-19.
Cultural Resource Assessment, Japanese Camp and Lavender Town. B Bowden, L L Larson, Larson Anthropological/Archaeological Services. Bowden, B. and Larson, L. L. (1997). Cultural Resource Assessment, Japanese Camp and Lavender Town, Selleck, King County, Washington. Larson Anthropological/Archaeological Services, Seattle, WA.
Of seals, sea lions, and abalone: the archaeology of an historical multiethnic base camp on. T J Braje, J G Costello, J M Erlandson, R Delong, Historical Archaeology. 482Braje, T. J., Costello, J. G., Erlandson, J. M., and DeLong, R. (2014). Of seals, sea lions, and abalone: the archaeology of an historical multiethnic base camp on San Miguel Island, California. Historical Archaeology 48(2): 122-142.
Rice Bowls and Resistance: Cultural Persistence at the Manzanar War Relocation Center. N L Branton, California; TucsonDepartment of Anthropology, University of ArizonaMaster's thesisBranton, N. L. (2000). Rice Bowls and Resistance: Cultural Persistence at the Manzanar War Relocation Center, California, 1942-1945. Master's thesis, Department of Anthropology, University of Arizona, Tucson.
Drawing the Line: Places of Power in the Japanese-American Internment Eventscape. Doctoral dissertation. N L Branton, TucsonDepartment of Anthropology, University of ArizonaBranton, N. L. (2004). Drawing the Line: Places of Power in the Japanese-American Internment Eventscape. Doctoral dissertation, Department of Anthropology, University of Arizona, Tucson.
Landscape approaches in historical archaeology: the archaeology of places. N Branton, Majewski, T. and Gaimster, D.SpringerNew YorkInternational Handbook of Historical ArchaeologyBranton, N. (2009). Landscape approaches in historical archaeology: the archaeology of places. In Majewski, T. and Gaimster, D. (eds.), International Handbook of Historical Archaeology. Springer, New York, pp. 51-65.
Artifacts from the LaFarge Site. J Brock, W A Sawyer, P W Wormser, Archaeological Advisory Group. Brock, J., Sawyer, W. A., and Wormser, P. W. (1988). Artifacts from the LaFarge Site, Redlands, California. Archaeological Advisory Group, Newport Beach, CA.
The eclipse of history: Japanese America and a treasure chest of forgetting. K Brown, Public Culture. 9Brown, K. (1996). The eclipse of history: Japanese America and a treasure chest of forgetting. Public Culture 9: 69-91.
The Tudela Site: fire and steel over Saipan. L E Bulgrin, Journal of Conflict Archaeology. 151Bulgrin, L. E. (2005). The Tudela Site: fire and steel over Saipan, 15 June 1944. Journal of Conflict Archaeology 1(1): 1-18.
L E Bulgrin, Trade in Ceramics on Guam in the Wake of the Manila Galleon. The MUA Collection. Bulgrin, L. E. (2017). Trade in Ceramics on Guam in the Wake of the Manila Galleon. The MUA Collection, http://www.themua.org/collections/items/show/1829, accessed August, 2020.
Three Farewells to Manzanar: The Archaeology of Manzanar National Historic Site. J F Burton, California. National Park Service; Tucson, AZBurton, J. F. (ed.) (1996). Three Farewells to Manzanar: The Archaeology of Manzanar National Historic Site, California. National Park Service, Tucson, AZ.
Archaeological Investigations at the Administration Block and Entrance, Manzanar National Historic Site. J F Burton, National Park Service. Burton, J. F. (2005a). Archaeological Investigations at the Administration Block and Entrance, Manzanar National Historic Site. National Park Service, Tucson, AZ.
J F Burton, The Fate of Things: Archaeological Investigations at the Minidoka Relocation Center Dump. Jerome County, Idaho. National Park Service; Tucson, AZBurton, J. F. (2005b). The Fate of Things: Archaeological Investigations at the Minidoka Relocation Center Dump, Jerome County, Idaho. National Park Service, Tucson, AZ.
J F Burton, Poston Relocation Center: Historical Resources Inventory. Tucson, AZBurton, J. F. (2006). Poston Relocation Center: Historical Resources Inventory. National Park Service, Tucson, AZ.
America's World War II internment camps: Japanese American patriotism and defiance at Manzanar. J F Burton, Historical Archaeologies of Cognition: Explorations into Faith. Symonds, J., Badcock, A., and Oliver, J.Hope and Charity. Equinox, SheffieldBurton, J. F. (2013). America's World War II internment camps: Japanese American patriotism and defiance at Manzanar. In Symonds, J., Badcock, A., and Oliver, J. (eds.), Historical Archaeologies of Cognition: Explorations into Faith, Hope and Charity. Equinox, Sheffield, pp. 132-146.
Garden Management Plan: Gardens and Gardeners at Manzanar. Manzanar National Historic Site. J F Burton, National Park Service, Independence, CABurton, J. F. (2015). Garden Management Plan: Gardens and Gardeners at Manzanar. Manzanar National Historic Site, National Park Service, Independence, CA.
Excavating legacy: community archaeology at a Japanese American World War II incarceration site. J F Burton, Journal of Community Archaeology and Heritage. 43Burton, J. F. (2017). Excavating legacy: community archaeology at a Japanese American World War II incarceration site. Journal of Community Archaeology and Heritage 4(3): 160-172.
Archeological and Preservation Work at the Chicken Ranch. J F Burton, Manzanar Relocation Center, California. Manzanar National Historic Site, National Park Service, Independence, CABurton, J. F. (2019). Archeological and Preservation Work at the Chicken Ranch 2009-2018, Manzanar Relocation Center, California. Manzanar National Historic Site, National Park Service, Independence, CA.
This Is Minidoka: An Archaeological Survey of Minidoka Internment National Monument. J F Burton, M M Farrell, Idaho. National Park Service; Tucson, AZBurton, J. F. and Farrell, M. M. (2001). This Is Minidoka: An Archaeological Survey of Minidoka Internment National Monument, Idaho. National Park Service, Tucson, AZ.
Tule Lake Segregation Center: National Historic Landmark Nomination. J F Burton, M M Farrell, National Park Service. Burton, J. F. and Farrell, M. M. (2005). Tule Lake Segregation Center: National Historic Landmark Nomination. National Park Service, Tucson, AZ.
An Archaeological Survey of the John Herrmann "Farm-In-A-Day" Property. J F Burton, M M Farrell, Jerome County, Idaho. National Park Service; Tucson, AZBurton, J. F. and Farrell, M. M. (2006). An Archaeological Survey of the John Herrmann "Farm-In-A-Day" Property, Jerome County, Idaho. National Park Service, Tucson, AZ.
World War II Japanese American Internment Sites in Hawai'i. J F Burton, M M Farrell, Trans-Sierran Archaeological Research. Burton, J. F. and Farrell, M. M. (2007). World War II Japanese American Internment Sites in Hawai'i. Trans- Sierran Archaeological Research, Tucson, AZ, in cooperation with Japanese Cultural Center of Hawai'i Research Center, Honolulu, HI.
Jigoku-Dani: An Archaeological Reconnaissance of the Honouliuli Internment Camp, O'ahu. J F Burton, M M Farrell, Trans-Sierran Archaeological Research. Burton, J. F. and Farrell, M. M. (2008). Jigoku-Dani: An Archaeological Reconnaissance of the Honouliuli Internment Camp, O'ahu, Hawai'i. Trans-Sierran Archaeological Research, Tucson, AZ, in cooperation with Japanese Cultural Center of Hawai'i Research Center, Honolulu, HI.
Life in Manzanar where there is a spring breeze": graffiti at a Word War II Japanese American internment camp. J F Burton, M M Farrell, Prisoners of War: Archaeology, Memory, and Heritage of 19th-and 20th-Century Mass Internment. Mytum, H. and Carr, G.New YorkSpringerBurton, J. F. and Farrell, M. M. (2013). "Life in Manzanar where there is a spring breeze": graffiti at a Word War II Japanese American internment camp. In Mytum, H. and Carr, G. (eds.), Prisoners of War: Archaeology, Memory, and Heritage of 19th-and 20th-Century Mass Internment. Springer, New York, pp. 239-269.
Creating beauty behind barbed wire: Manzanar's Japanese gardens. J Burton, M Farrell, Journal of the North American Japanese Garden Association. 2Burton, J. and Farrell, M. (2014). Creating beauty behind barbed wire: Manzanar's Japanese gardens. Journal of the North American Japanese Garden Association 2: 50-59.
The Archaeology of Somewhere: Archaeological Testing along US Highway 395. J F Burton, R E Hughes, T M Origer, C L Rogers, J A Waters, Manzanar National Historic Site, California. National Park Service; Tucson, AZBurton, J. F., Hughes, R. E., Origer, T. M., Rogers, C. L., and Waters, J. A. (1998). The Archaeology of Somewhere: Archaeological Testing along US Highway 395, Manzanar National Historic Site, California. National Park Service, Tucson, AZ.
Confinement and Ethnicity: An Overview of World War II Japanese American Relocation Sites. J F Burton, M M Farrell, F B Lord, R W Lord, National Park Service. Burton, J. F., Farrell, M. M., Lord, F. B., and Lord, R. W. (1999). Confinement and Ethnicity: An Overview of World War II Japanese American Relocation Sites. National Park Service, Tucson, AZ.
I Reo To: Archaeological Investigations at the Manzanar Relocation Center Cemetery, Manzanar Historic Site. J F Burton, J D Haines, M M Farrell, California. National Park Service; Tucson, AZBurton, J. F., Haines, J. D., and Farrell, M. M. (2001). I Reo To: Archaeological Investigations at the Manzanar Relocation Center Cemetery, Manzanar Historic Site, California. National Park Service, Tucson, AZ.
Minidoka Internment National Monument Archaeology at the Gate: Archaeological Investigations at the Entrance of the Minidoka Relocation Center. J F Burton, L S Bergstresser, A H Tamura, National Park Service. Burton, J. F., Bergstresser, L. S., and Tamura, A. H. (2003). Minidoka Internment National Monument Archaeology at the Gate: Archaeological Investigations at the Entrance of the Minidoka Relocation Center. National Park Service, Tucson, AZ.
A Place of Beauty and Serenity: Excavation and Restoration of the Arai Family Fish Pond, Block 33, Barracks 4. Manzanar National Historic Site. J F Burton, M M Farrell, E Brasfield, E Noguchi, R Potashin, L W Ng, National Park Service, Independence, CABurton, J. F., Farrell, M. M., Brasfield, E., Noguchi, E., Potashin, R., and Ng, L. W. (2014a). A Place of Beauty and Serenity: Excavation and Restoration of the Arai Family Fish Pond, Block 33, Barracks 4. Manzanar National Historic Site, National Park Service, Independence, CA.
Breaking the Silence: Lessons of Democracy and Social Justice from the World War II Honouliuli Internment and POW Camp in Hawai'i. J Burton, M Farrell, L Kaneko, L Maldonato, Altenhofen , K , Falgout, S. and Nishigaya, L.HonoluluUniversity of Hawai'i PressHell Valley: uncovering a prison camp in ParadiseBurton, J., Farrell, M., Kaneko, L., Maldonato, L., and Altenhofen, K. (2014b). Hell Valley: uncovering a prison camp in Paradise. In Falgout, S. and Nishigaya, L. (eds.), Breaking the Silence: Lessons of Democracy and Social Justice from the World War II Honouliuli Internment and POW Camp in Hawai'i, University of Hawai'i Press, Honolulu, pp. 43-79.
Uncovering Community: The Archaeology of Block 15, Manzanar Relocation Center. J F Burton, K W Gobalet, N Valente, Manzanar National Historic SiteNational Park Service, Independence, CABurton, J. F., Gobalet, K. W., and Valente, N. (2017). Uncovering Community: The Archaeology of Block 15, Manzanar Relocation Center. Manzanar National Historic Site, National Park Service, Independence, CA.
An archaeological landscape of the Pacific War: the Palau Islands. B M Butler, D Snyder, Archaeological Studies of World War II. Wood, R.Museum of Anthropology, University of Missouri-ColumbiaButler, B. M. and Snyder, D. (1991). An archaeological landscape of the Pacific War: the Palau Islands. In Wood, R. (ed.), Archaeological Studies of World War II, Museum of Anthropology, University of Missouri-Columbia, pp. 48-63.
The use of simulation models to estimate frequency and location of Japanese Edo Period wrecks along the Canadian Pacific coast. R T Callaghan, Canadian Journal of Archaeology. 271Callaghan, R. T. (2003). The use of simulation models to estimate frequency and location of Japanese Edo Period wrecks along the Canadian Pacific coast. Canadian Journal of Archaeology 27(1): 74-94.
Historical Archaeology and the Importance of Material Things II. S L Camp, Society for Historical Archaeology. Schablitsky, J. M. and Leone, M. P.The utility of comparative research in Historical ArchaeologyCamp, S. L. (2011). The utility of comparative research in Historical Archaeology. In Schablitsky, J. M. and Leone, M. P. (eds.), Historical Archaeology and the Importance of Material Things II. Society for Historical Archaeology, Germantown, MD, pp. 13-29.
Landscapes of Japanese American internment. S L Camp, Historical Archaeology. Gainesville. Camp, S. L.501University Press of FloridaThe Archaeology of CitizenshipCamp, S. L. (2013). The Archaeology of Citizenship. University Press of Florida, Gainesville. Camp, S. L. (2016). Landscapes of Japanese American internment. Historical Archaeology 50(1): 169-186.
Commentary: excavating the intimate. S L Camp, Historical Archaeology. 523Camp, S. L. (2018a). Commentary: excavating the intimate. Historical Archaeology 52(3): 600-608.
Visual and ocular health at a World War II internment camp. S L Camp, World Archaeology. 503Camp, S. L. (2018b). Visual and ocular health at a World War II internment camp. World Archaeology 50(3): 530-546.
Connections and Distinctions: Historical Archaeological Analysis of Japanese Ceramics Recovered from Three Issei Communities in the American West. R J Campbell, MoscowUniversity of IdahoMaster's thesisCampbell, R. J. (2017a). Connections and Distinctions: Historical Archaeological Analysis of Japanese Ceramics Recovered from Three Issei Communities in the American West, 1903-1942. Master's thesis, University of Idaho, Moscow.
Reanalysis of Japanese-manufactured ceramics recovered from Japanese Gulch Village. R J Campbell, Archaeology in Washington. 17Campbell, R. J. (2017b). Reanalysis of Japanese-manufactured ceramics recovered from Japanese Gulch Village (1903-1930), Mukilteo, Washington. Archaeology in Washington 17: 62-89.
Historical Japanese Ceramic Comparative Collection: Japanese Ceramics from Archaeological Sites in the American West. R J Campbell, University of Idaho Digital InitiativesCampbell, R. J. (2019). Historical Japanese Ceramic Comparative Collection: Japanese Ceramics from Archaeological Sites in the American West. University of Idaho Digital Initiatives, https://www.lib. uidaho.edu/digital/hjccc/, accessed August, 2020.
Camp Amache (5PW48): A Class III Intensive Field Survey of the Granada Relocation Center. R F Carillo, D Killam, Prowers County, Colorado. RMC ConsultantsCarillo, R. F. and Killam, D. (2004). Camp Amache (5PW48): A Class III Intensive Field Survey of the Granada Relocation Center, Prowers County, Colorado. RMC Consultants.
The Issei at Barneston Project: an investigation into issues of race and labor at an early twentieth-century Japanese-American sawmill community. D R Carlson, Archaeology in Washington. 17Carlson, D. R. (2017). The Issei at Barneston Project: an investigation into issues of race and labor at an early twentieth-century Japanese-American sawmill community. Archaeology in Washington 17: 30-61.
Forgotten and refound military structures in the central Pacific: examples from the Marshall Islands. E C Casella, Gainesville, H Christiansen, Matériel Culture: The Archaeology of Twentieth-Century Conflict. Routledge. Schofield, J., Johnson, W. G., and Beck, C. M.New YorkUniversity Press of FloridaThe Archaeology of Institutional ConfinementCasella, E. C. (2007). The Archaeology of Institutional Confinement. University Press of Florida, Gainesville. Christiansen, H. (2002). Forgotten and refound military structures in the central Pacific: examples from the Marshall Islands. In Schofield, J., Johnson, W. G., and Beck, C. M. (eds.), Matériel Culture: The Archaeology of Twentieth-Century Conflict. Routledge, New York, pp. 58-64.
The archaeology of entryway gardens at Amache. B J Clark, Journal of the North American Japanese Garden Association. 4Clark, B. J. (2017a). The archaeology of entryway gardens at Amache. Journal of the North American Japanese Garden Association 4: 28-33.
Cultivating community: the archaeology of Japanese American confinement at Amache. B J Clark, Legacies of Space and Intangible Heritage: Archaeology, Ethnohistory, and the Politics of Cultural Continuity in the Americas. Armstrong-Fumero, F. and Gutierrez, J. H.BoulderUniversity Press of ColoradoClark, B. J. (2017b). Cultivating community: the archaeology of Japanese American confinement at Amache. In Armstrong-Fumero, F. and Gutierrez, J. H. (eds.), Legacies of Space and Intangible Heritage: Archaeology, Ethnohistory, and the Politics of Cultural Continuity in the Americas. University Press of Colorado, Boulder, pp. 79-96.
Digging yesterday: the archaeology of living memory at Amache. B J Clark, Warner, M. and Purser, M.University of Nebraska PressLincolnHistorical Archaeology through a Western LensClark, B. J. (2017c). Digging yesterday: the archaeology of living memory at Amache. In Warner, M. and Purser, M. (eds.), Historical Archaeology through a Western Lens. University of Nebraska Press, Lincoln, pp. 210-232.
Artifacts, contested histories, and other archaeological hotspots. B J Clark, Historical Archaeology. 523Clark, B. J. (2018). Artifacts, contested histories, and other archaeological hotspots. Historical Archaeology 52(3): 544-552.
Finding Solace in the Soil: An Archaeology of Gardens and Gardeners at Amache. B J Clark, University of Colorado PressBoulderClark, B. J. (2020). Finding Solace in the Soil: An Archaeology of Gardens and Gardeners at Amache. University of Colorado Press, Boulder.
Powerful objects, difficult dialogues: mobilizing archaeological exhibits for civic engagement. B J Clark, A Amati, International Journal of Heritage Studies. 257Clark, B. J. and Amati, A. (2019). Powerful objects, difficult dialogues: mobilizing archaeological exhibits for civic engagement. International Journal of Heritage Studies 25(7): 708-721.
Excavation of the Marpole-Eburne Site (DhRs 25): An Urban Garbage Dump in an Early Vancouver Suburb. S A Copp, Vancouver Community CollegeLangara Campus, Vancouver, BCCopp, S. A. (1987). Excavation of the Marpole-Eburne Site (DhRs 25): An Urban Garbage Dump in an Early Vancouver Suburb. Vancouver Community College, Langara Campus, Vancouver, BC.
Rice Bowls in the Delta: Artifacts Recovered from the 1915 Asian Community of Walnut Grove. J G Costello, M L Maniery, Los AngelesCalifornia. Institute of Archaeology, University of CaliforniaCostello, J. G. and Maniery, M. L. (1988). Rice Bowls in the Delta: Artifacts Recovered from the 1915 Asian Community of Walnut Grove, California. Institute of Archaeology, University of California, Los Angeles.
Historic Study Report for Three Historic-Period Resources on the Golf Club Rehabilitation Project on US 395 near Bishop. J G Costello, J Marvin, S Baker, L E Bibb, Foothill Resources Ltd. Costello, J. G., Marvin, J., Baker, S., and Bibb, L. E. (2001). Historic Study Report for Three Historic-Period Resources on the Golf Club Rehabilitation Project on US 395 near Bishop, Inyo County, California. Foothill Resources Ltd., Bishop, CA.
A comprised archaeological history of Taiwan through the long-term record of Heping Dao. Cruz Berrocal, Serrano María, E Herrero, M Gener Moret, A Uriarte González, M Torra Pérez, S Consuegra Rodríguez, A Chevalier, F Valentin, C Tsang, Keelung. International Journal of Historical Archaeology. 22Cruz Berrocal, María, Serrano Herrero, E., Gener Moret, M., Uriarte González, A., Torra Pérez, M., Consuegra Rodríguez, S., Chevalier, A., Valentin, F., and Tsang, C. (2018). A comprised archaeological history of Taiwan through the long-term record of Heping Dao, Keelung. International Journal of Historical Archaeology 22: 905-940.
Dip into Soba-Choko. Asian American Comparative Collection Newsletter. Y Danner, Supplement. 373Danner, Y. (2020). Dip into Soba-Choko. Asian American Comparative Collection Newsletter, Supplement 37(3): 5-6.
Archaeological Monitoring at Britannia Heritage Shipyard. Deva Heritage Consulting. Deva Heritage Consulting. (1994). Archaeological Monitoring at Britannia Heritage Shipyard, Richmond, BC. Deva Heritage Consulting, Vancouver, BC.
The archaeology of rural settlement and class in a pre-WWII Japanese plantation on Tinian, Commonwealth of the Northern Mariana Islands. B Dixon, International Journal of Historical Archaeology. 84Dixon, B. (2004). The archaeology of rural settlement and class in a pre-WWII Japanese plantation on Tinian, Commonwealth of the Northern Mariana Islands. International Journal of Historical Archaeology 8(4): 281-99.
Okinawa as transported landscape: understanding Japanese archaeological remains on Tinian using Ryūkyū ethnohistory and ethnography. B Dixon, Asian Perspectives. 542Dixon, B. (2016). Okinawa as transported landscape: understanding Japanese archaeological remains on Tinian using Ryūkyū ethnohistory and ethnography. Asian Perspectives 54(2): 274-304.
The Japanese diaspora in Micronesia: its archaeological context. The International Journal of the Japanese Diaspora. Dixon, B. and Tuggle, D.10part 1. Pan-JapanDixon, B. and Tuggle, D. (eds.) (2014). The Japanese diaspora in Micronesia: its archaeological context, part 1. Pan-Japan: The International Journal of the Japanese Diaspora 10(1-2).
The archaeology of World War II Japanese stragglers on the Island of Guam and the Bushido Code. B Dixon, L Gilda, L Bulgrin, Asian Perspectives. 511Dixon, B., Gilda, L., and Bulgrin, L. (2012). The archaeology of World War II Japanese stragglers on the Island of Guam and the Bushido Code. Asian Perspectives 51(1): 110-127.
Brewing Behind Barbed Wire: An Archaeology of Saké at Amache. Master's thesis. C A Driver, Denver, COUniversity of DenverDriver, C. A. (2015). Brewing Behind Barbed Wire: An Archaeology of Saké at Amache. Master's thesis, University of Denver, Denver, CO.
Deru Kugi Wa Utareru or the nail that sticks up gets hit: the architecture of Japanese American identity, 1885-1942, the rural environment. G L Dubrow, Journal of Architectural and Planning Research. 194Dubrow, G. L. (2002). Deru Kugi Wa Utareru or the nail that sticks up gets hit: the architecture of Japanese American identity, 1885-1942, the rural environment. Journal of Architectural and Planning Research 19(4): 319-333.
The nail that sticks up gets hit": the architecture of Japanese American identity in the urban environment. G L Dubrow, Nikkei in the Pacific Northwest: Japanese Americans and Japanese Canadians in the Twentieth Century. Fiset, L. and Nomura, G. M.SeattleUniversity of Washington PressDubrow, G. L. (2005). "The nail that sticks up gets hit": the architecture of Japanese American identity in the urban environment, 1885-1942. In Fiset, L. and Nomura, G. M. (eds.), Nikkei in the Pacific Northwest: Japanese Americans and Japanese Canadians in the Twentieth Century. University of Washington Press, Seattle, pp. 117-138.
Sento at Sixth and Main: Preserving Landmarks of Japanese American Heritage. G Dubrow, D Graves, Seattle Arts Commission. Dubrow, G. and Graves, D. (2002). Sento at Sixth and Main: Preserving Landmarks of Japanese American Heritage. Seattle Arts Commission, Seattle, WA.
Artifacts of Loss: Crafting Survival in Japanese American Concentration Camps. J E Dusselier, Rutgers University PressNew Brunswick, NJDusselier, J. E. (2008). Artifacts of Loss: Crafting Survival in Japanese American Concentration Camps. Rutgers University Press, New Brunswick, NJ.
Cultural Resource Assessment for the Gila River Farms Indian Community. R W Effland, Jr Green, M , GRIC. Archaeological Consulting Services, Ltd. Effland, R. W., Jr. and Green, M. (1983). Cultural Resource Assessment for the Gila River Farms Indian Community, GRIC. Archaeological Consulting Services, Ltd., Phoenix, AZ.
McLean Mill National Historic Site: Archaeological Assessment. Millennia Research. M Eldridge, C D Coates, Sidney, BCEldridge, M. and Coates, C. D. (1994). McLean Mill National Historic Site: Archaeological Assessment. Millennia Research, Sidney, BC.
Site Documentation and Management Plan for the Topaz Relocation Center. S M Ellis, Millard County, Utah; Delta, UTSWCA Environmental ConsultantsEllis, S. M. (2002). Site Documentation and Management Plan for the Topaz Relocation Center, Millard County, Utah. SWCA Environmental Consultants, Delta, UT.
The Royal Presidio of Santa Barbara: Archaeology of the Chapel Site. Department of Parks and Recreation. B M Fagan, State of CaliforniaFagan, B. M. (1976). The Royal Presidio of Santa Barbara: Archaeology of the Chapel Site. Department of Parks and Recreation, State of California.
M Farrell, Archaeology of the Japanese American incarceration. Densho Encyclopedia. Farrell, M. (2015). Archaeology of the Japanese American incarceration. Densho Encyclopedia, http:// encyclopedia.densho.org/Archaeology%20of%20the%20Japanese%20American%20incarceration/, accessed July, 2020.
Dark Clouds over Paradise: An Overview of World War II Japanese Confinement Sites in Hawaii. M Farrell, Japanese Cultural Center of Hawaii. HonoluluFarrell, M. (2017a). Dark Clouds over Paradise: An Overview of World War II Japanese Confinement Sites in Hawaii. Japanese Cultural Center of Hawaii, Honolulu.
Honouliuli POW and Internment Camp Archaeological Investigations at Jigoku-Dani. M Farrell, Japanese Cultural Center of Hawaii. Farrell, M. (2017b). Honouliuli POW and Internment Camp Archaeological Investigations at Jigoku-Dani 2006-2017. Japanese Cultural Center of Hawaii, Honolulu.
Civil rights and moral wrongs: World War II Japanese American relocation sites. M M Farrell, J F Burton, The SAA Archaeological Record. 45Farrell, M. M. and Burton, J. F. (2004). Civil rights and moral wrongs: World War II Japanese American relocation sites. The SAA Archaeological Record 4(5): 22-25, 28.
Gordon Hirabayashi, the Tucsonians, and the US Constitution: negotiating reconciliation in a landscape of exile. M M Farrell, J F Burton, Archaeologies of Internment. Myers, A. and Moshenska, G.New YorkSpringerFarrell, M. M. and Burton, J. F. (2011). Gordon Hirabayashi, the Tucsonians, and the US Constitution: negotiating reconciliation in a landscape of exile. In Myers, A. and Moshenska, G. (eds.), Archaeologies of Internment. Springer, New York, pp. 89-110.
Cold Cream, Masculinity, and Imprisonment: The Archaeology of Japanese American Internees at Idaho's Kooskia Internment Camp, 1943-1945. K Fitz-Gerald, Moscow, IDUniversity of IdahoMaster's thesisFitz-Gerald, K. (2015). Cold Cream, Masculinity, and Imprisonment: The Archaeology of Japanese American Internees at Idaho's Kooskia Internment Camp, 1943-1945. Master's thesis, University of Idaho, Moscow, ID.
The Japanese Consumer: An Alternative Economic History of Modern Japan. P Francks, Cambridge University PressCambridgeFrancks, P. (2009a). The Japanese Consumer: An Alternative Economic History of Modern Japan. Cambridge University Press, Cambridge.
Inconspicuous consumption: sake, beer, and the birth of the consumer in Japan. P Francks, Journal of Asian Studies. 681Francks, P. (2009b). Inconspicuous consumption: sake, beer, and the birth of the consumer in Japan. Journal of Asian Studies 68(1): 135-164.
Was fashion a European invention?: the kimono and economic development in Japan. P Francks, Fashion Theory. 193Francks, P. (2015). Was fashion a European invention?: the kimono and economic development in Japan. Fashion Theory 19(3): 331-362.
The Historical Consumer: Consumption and Everyday Life in Japan. P Francks, J Hunter, Palgrave MacmillanLondonFrancks, P. and Hunter, J. (eds.) (2012). The Historical Consumer: Consumption and Everyday Life in Japan, 1850-2000. Palgrave Macmillan, London.
The development of department stores in Japan: 1900s-1930s. R Fujioka, Japanese Research in Business History. 31Fujioka, R. (2014). The development of department stores in Japan: 1900s-1930s. Japanese Research in Business History 31: 11-27.
Returning to Amache: former Japanese American internees assist archaeological research team. D K Fujita, Historical Archaeology. 523Fujita, D. K. (2018). Returning to Amache: former Japanese American internees assist archaeological research team. Historical Archaeology 52(3): 553-560.
Historic Japanese sites of southwestern Wyoming revised and revisited: Japanese rock art and tombstones: immigration patterns on the Northern Plains and in the Rocky Mountains. A D Gardner, D E Johnson, Wyoming Archaeologist. 452Gardner, A. D. and Johnson, D. E. (2001). Historic Japanese sites of southwestern Wyoming revised and revisited: Japanese rock art and tombstones: immigration patterns on the Northern Plains and in the Rocky Mountains. Wyoming Archaeologist 45(2): 29-38.
Historic Japanese sites of southwestern Wyoming. A D Gardner, M A Matthews, Johnson , D E , Wyoming Archaeologist. 313-4Gardner, A. D., Matthews, M. A., and Johnson, D. E. (1988). Historic Japanese sites of southwestern Wyoming. Wyoming Archaeologist 31(3-4): 67-82.
A History of Transplants: A Study of Entryway Gardens at Amache. Master's thesis. D H Garrison, Denver, COUniversity of DenverGarrison, D. H. (2015). A History of Transplants: A Study of Entryway Gardens at Amache. Master's thesis, University of Denver, Denver, CO.
Heart Mountain Relocation Center National Register of Historic Places-Nomination Form. Wyoming Recreation Commission. M Gorman, CheyenneGorman, M. (1985). Heart Mountain Relocation Center National Register of Historic Places-Nomination Form. Wyoming Recreation Commission, Cheyenne.
B. C. Hydro's Bridge River Townsite Redevelopment Project Archaeological Impact Assessment. N Gray, GWR Heritage ConsultingKamloops, BCGray, N. (2009). B. C. Hydro's Bridge River Townsite Redevelopment Project Archaeological Impact Assessment. GWR Heritage Consulting, Kamloops, BC.
The Changing Faces of Main Street: Ventura Mission Plaza Archaeological Project. R S Greenwood, Ventura, CAGreenwood, R. S. (1976). The Changing Faces of Main Street: Ventura Mission Plaza Archaeological Project. Ventura, CA.
Down by the Station. R S Greenwood, Los Angeles Chinatown; Los Angeles, CAInstitute of Archaeology, University of CaliforniaGreenwood, R. S. (1996). Down by the Station: Los Angeles Chinatown, 1880-1933. Institute of Archaeology, University of California, Los Angeles, CA.
Japanese pearlers' bath-house. G Grimwade, Memoirs of the Queensland Museum Cultural Heritage Series. 31Grimwade, G. (2004). Japanese pearlers' bath-house, Thursday Island, Torres Strait. Memoirs of the Queensland Museum Cultural Heritage Series 3(1): 379-386.
Deconstructing a global commodity: coffee, culture, and consumption in Japan. H Grinshpun, Journal of Consumer Culture. 143Grinshpun, H. (2014). Deconstructing a global commodity: coffee, culture, and consumption in Japan. Journal of Consumer Culture 14(3): 343-364.
H H Hammatt, Archaeological Inventory Survey Report For City Center (Section 4) of the Honolulu High-Capacity Transit Corridor Project, Kalihi, Kapālama, Honolulu, and Waikīkī Ahupua'a, Honolulu (Kona) District. Iwilei. Cultural Surveys Hawai'i, KailuaIVBIsland of O'ahu, TMK [1] 1-2, 1-5, 1-7, 2-1, 2-3 (Various Plats and Parcels. Excavation Results: Zone 3, West Kapālama; Zone 4, East Kapālama; and Zone 5Hammatt, H. H. (2013a). Archaeological Inventory Survey Report For City Center (Section 4) of the Honolulu High-Capacity Transit Corridor Project, Kalihi, Kapālama, Honolulu, and Waikīkī Ahupua'a, Honolulu (Kona) District, Island of O'ahu, TMK [1] 1-2, 1-5, 1-7, 2-1, 2-3 (Various Plats and Parcels), Volume IVB, Excavation Results: Zone 3, West Kapālama; Zone 4, East Kapālama; and Zone 5, Iwilei. Cultural Surveys Hawai'i, Kailua.
Excavation Results: Zone 6, Downtown Waterfront. H H Hammatt, Archaeological Inventory Survey Report For City Center (Section 4) of the Honolulu High-Capacity Transit Corridor Project, Kalihi, Kapālama, Honolulu, and Waikīkī Ahupua'a, Honolulu (Kona) District. Zone 7, West Kaka'ako; KailuaIVCIsland of O'ahu, TMK [1] 1-2, 1-5, 1-7, 2-1, 2-3 (Various Plats and Parcels. and Zone 8, Kewalo. Cultural Surveys Hawai'iHammatt, H. H. (2013b). Archaeological Inventory Survey Report For City Center (Section 4) of the Honolulu High-Capacity Transit Corridor Project, Kalihi, Kapālama, Honolulu, and Waikīkī Ahupua'a, Honolulu (Kona) District, Island of O'ahu, TMK [1] 1-2, 1-5, 1-7, 2-1, 2-3 (Various Plats and Parcels), Volume IVC, Excavation Results: Zone 6, Downtown Waterfront; Zone 7, West Kaka'ako; and Zone 8, Kewalo. Cultural Surveys Hawai'i, Kailua.
Everyday Things in Premodern Japan: The Hidden Legacy of Material Culture. S B Hanley, University of California PressBerkeleyHanley, S. B. (1997). Everyday Things in Premodern Japan: The Hidden Legacy of Material Culture. University of California Press, Berkeley.
Yama and beyond: construction and negotiation of identity at a late nineteenth-to early twentieth-century Japanese-American community. C M Hartse, Archaeology in Washington. 17Hartse, C. M. (2017). Yama and beyond: construction and negotiation of identity at a late nineteenth-to early twentieth-century Japanese-American community. Archaeology in Washington 17: 16-29.
Archaeological and Historical Studies at Ninth and Amherst. E M Hattori, M K Rusco, D R Tuohy, Nevada State Museum Archaeological Services. Hattori, E. M., Rusco, M. K., and Tuohy, D. R. (1979). Archaeological and Historical Studies at Ninth and Amherst, Lovelock, Nevada. Nevada State Museum Archaeological Services, Carson City, NV.
Archaeological Resource Management Programme: Canadian Parks Service, Western Region National Parks and National Historic Sites, Archaeological Services. Department of Canadian Heritage. R J Heitzmann, Francis, P. D.Parks Canada, Calgary, ABGulf of Georgia Cannery (Site 351T)Heitzmann, R. J. (1994). Gulf of Georgia Cannery (Site 351T). In Francis, P. D. (ed.), 1991-92 Archaeological Resource Management Programme: Canadian Parks Service, Western Region National Parks and National Historic Sites, Archaeological Services. Department of Canadian Heritage, Parks Canada, Calgary, AB, pp. 241-249.
Defiant Gardens: Makings Gardens in Wartime. K I Helphand, Trinity University PressSan Antonio, TXHelphand, K. I. (2006). Defiant Gardens: Makings Gardens in Wartime. Trinity University Press, San Antonio, TX.
Dislocations and Relocations: The Built Environments of Japanese American Internment. Doctoral dissertation. C L Horiuchi, Santa BarbaraUniversity of CaliforniaHoriuchi, C. L. (2005). Dislocations and Relocations: The Built Environments of Japanese American Internment. Doctoral dissertation, University of California, Santa Barbara.
Temporal cities: commemoration at Manzanar, California and Cowra. L Horiuchi, A Pieris, Australia. Asian Diasporic Visual Cultures and the Americas. 3Horiuchi, L. and Pieris, A. (2017). Temporal cities: commemoration at Manzanar, California and Cowra, Australia. Asian Diasporic Visual Cultures and the Americas 3: 292-321.
Caring for their prisoner compatriots": health and dental hygiene at the Kooskia internment camp. K Hosken, K Tiede, Historical Archaeology. 523Hosken, K. and Tiede, K. (2018). "Caring for their prisoner compatriots": health and dental hygiene at the Kooskia internment camp. Historical Archaeology 52(3): 585-599.
Coffee production in the Asia-Pacific region: the establishment of a Japanese diasporic network in the early 20 th century. M Iijima, Journal of International Economic Studies. 32Iijima, M. (2018). Coffee production in the Asia-Pacific region: the establishment of a Japanese diasporic network in the early 20 th century. Journal of International Economic Studies 32: 75-88.
Sugar Islands in the Pacific in the early twentieth century: Taiwan as a protégé of Hawaii. M Iijima, Historische Anthropologie. 273Iijima, M. (2019). Sugar Islands in the Pacific in the early twentieth century: Taiwan as a protégé of Hawaii. Historische Anthropologie 27(3): 361-384.
Creating the Nisei Market: Race and Citizenship in Hawai'i's Japanese American Consumer Culture. S Imai, HonoluluUniversity of Hawai'i PressImai, S. (2010). Creating the Nisei Market: Race and Citizenship in Hawai'i's Japanese American Consumer Culture. University of Hawai'i Press, Honolulu.
Weedy shrubs shroud stone: uncovering the role of Senryu poetry and immigration in Japanese communities of Washington. P Johnson, Archaeology in Washington. 17Johnson, P. (2017). Weedy shrubs shroud stone: uncovering the role of Senryu poetry and immigration in Japanese communities of Washington. Archaeology in Washington 17: 90-101.
Sake Bottles and Tea Bowls: Japanese Workers in a Northwest Logging Camp. Paper presented at the Northwest Anthropological Conference. G Kaehler, Pullman, WashingtonKaehler, G. (2007). Sake Bottles and Tea Bowls: Japanese Workers in a Northwest Logging Camp. Paper presented at the Northwest Anthropological Conference, Pullman, Washington.
Creating a community in confinement: the development of neighborhoods in Amache, a World War II Japanese American internment camp. A Kamp-Whittaker, C O Denver, A Kamp-Whittaker, B Clark, The Archaeology of Removal in North America. Weik, T.GainesvilleUniversity Press of FloridaDepartment of Anthropology, University of DenverThrough the Eyes of a Child: The Archaeology of WWII Japanese American Internment at AmacheKamp-Whittaker, A. (2010). Through the Eyes of a Child: The Archaeology of WWII Japanese American Internment at Amache. Master's thesis, Department of Anthropology, University of Denver, Denver, CO. Kamp-Whittaker, A. and Clark, B. (2019a). Creating a community in confinement: the development of neighborhoods in Amache, a World War II Japanese American internment camp. In Weik, T. (ed.), The Archaeology of Removal in North America. University Press of Florida, Gainesville, pp. 157-188.
Social networks and the development of neighborhood identities in Amache, a WWII Japanese American internment camp. A Kamp-Whittaker, B Clark, Archaeological Papers of the American Anthropological Association. 30Kamp-Whittaker, A. and Clark, B. (2019b). Social networks and the development of neighborhood identities in Amache, a WWII Japanese American internment camp. Archaeological Papers of the American Anthropological Association 30: 148-158.
Japanese Shipwrecks in British Columbia: Myths and Facts. G Keddie, Royal BC Museum. Keddie, G. (2013). Japanese Shipwrecks in British Columbia: Myths and Facts. Royal BC Museum, http:// staff.royalbcmuseum.bc.ca/2013/08/29/japanese-shipwrecks/, accessed August, 2020.
Pisekin Nóómw Nóón Tonaachaw: Archaeology in the Tonaachaw Historic District, Moen Island. T F King, P L Parker, CarbondaleCenter for Archaeological Investigations, Southern Illinois UniversityKing, T. F. and Parker, P. L. (1984). Pisekin Nóómw Nóón Tonaachaw: Archaeology in the Tonaachaw Historic District, Moen Island. Center for Archaeological Investigations, Southern Illinois University, Carbondale.
C Kraus-Friedberg, Where You Stay?": Transnational Identity in Sugar Plantation Worker Cemeteries. Pahala, Hawai'i. Doctoraldissertation, University of Pennsylvania, PhiladelphiaKraus-Friedberg, C. (2008). "Where You Stay?": Transnational Identity in Sugar Plantation Worker Cemeteries, Pahala, Hawai'i. Doctoraldissertation, University of Pennsylvania, Philadelphia.
Across the Pacific: transnational context in the Japanese plantation workers' cemetery in Pahala, Hawai'i. C Kraus-Friedberg, International Journal of Historical Archaeology. 15Kraus-Friedberg, C. (2011). Across the Pacific: transnational context in the Japanese plantation workers' cemetery in Pahala, Hawai'i. International Journal of Historical Archaeology 15: 381-408.
Loving Luxury: The Cultural Economy of the Japanese American Home, 1920s. Doctoral dissertation. C Y Lau, Santa BarbaraUniversity of CaliforniaLau, C. Y. (2013). Loving Luxury: The Cultural Economy of the Japanese American Home, 1920s. Doctoral dissertation, University of California, Santa Barbara.
Dissonant memories of Japanese American incarceration. K Lau-Ozawa, International Journal of Heritage Studies. 257Lau-Ozawa, K. (2019a). Dissonant memories of Japanese American incarceration. International Journal of Heritage Studies 25(7): 656-670.
New connections between pre-war communities and Japanese American incarceration camps. Asian American Comparative Collection Newsletter. K Lau-Ozawa, Supplement. 361Lau-Ozawa, K. (2019b). New connections between pre-war communities and Japanese American incarcera- tion camps. Asian American Comparative Collection Newsletter, Supplement 36(1): 5-6.
Metro Alki Transfer/CSO Project, Allentown Site (45-KI-431). D E Lewarch, L L Larson, J Robbins, P S Solimano, Larson Anthropological/Archaeological Services. Lewarch, D. E., Larson, L. L., Robbins, J., and Solimano, P. S. (1993). Metro Alki Transfer/CSO Project, Allentown Site (45-KI-431). Larson Anthropological/Archaeological Services, Seattle, WA.
Cultural Resources Survey of the Additional Water Storage Project Area. D E Lewarch, L A Forsman, L L Larson, Larson Anthropological/ Archaeological Services. Howard A. Hanson DamLewarch, D. E., Forsman, L. A., and Larson, L. L. (1996). Cultural Resources Survey of the Additional Water Storage Project Area, Howard A. Hanson Dam, King County, Washington. Larson Anthropological/ Archaeological Services, Seattle, Washington.
National Register of Historic Places Determination of Eligibility Report, Bacon Island Rural Historic District. M L Maniery, California. PAR Environmental Services Inc. Maniery, M. L. (1993). National Register of Historic Places Determination of Eligibility Report, Bacon Island Rural Historic District, San Joaquin County, California. PAR Environmental Services Inc., Sacramento, CA.
The archaeology of Asian immigrants: 35 years in the making. M L Maniery, The SAA Archaeological Record. 45Maniery, M. L. (2004). The archaeology of Asian immigrants: 35 years in the making. The SAA Archaeological Record 4(5): 10-13.
Celadons and sake bottles: Asian history underground. M L Maniery, J G Costello, Pacific Historian. 304Maniery, M. L. and Costello, J. G. (1986). Celadons and sake bottles: Asian history underground. Pacific Historian 30(4): 36-46.
National Register of Historic Places Determination of Eligibility Report for Three Historic Sites in Contra Costa and San Joaquin Counties. M L Maniery, L Fryman, California. PAR Environmental Services Inc. Maniery, M. L. and Fryman L. (1993). National Register of Historic Places Determination of Eligibility Report for Three Historic Sites in Contra Costa and San Joaquin Counties, California. PAR Environmental Services Inc., Sacramento, CA.
Down to the Last Grain of Rice: Japantown Senior Apartments. S Massey, D O Shew, A Praetzellis, Archaeological Investigations Final Technical Report. Anthropological Studies Center. Sonoma State UniversityMassey, S., Shew, D. O., and Praetzellis, A. (2013). Down to the Last Grain of Rice: Japantown Senior Apartments, San Jose, Archaeological Investigations Final Technical Report. Anthropological Studies Center, Sonoma State University, Rohnert Park, CA.
Archaeological Inventory Survey of the Pavia Property. W K Mcelroy, T. S. Dye & Colleagues, Archaeologists, Ltd. McElroy, W. K. (2003a). Archaeological Inventory Survey of the Pavia Property, Hā`ena, Kaua`i. T. S. Dye & Colleagues, Archaeologists, Ltd., Honolulu, HI.
Archaeological Monitoring of a Communication Line Installation at Hickam Air Force Base. W K Mcelroy, O`ahu, Hawai`i. T. S.Dye & Colleagues, Archaeologists, IncHonolulu, HIMcElroy, W. K. (2003b). Archaeological Monitoring of a Communication Line Installation at Hickam Air Force Base, O`ahu, Hawai`i. T. S. Dye & Colleagues, Archaeologists, Inc., Honolulu, HI.
Successes and failures among porcelain trading firms in the early Meiji Period. H Miyachi, Japanese Research in Business History. 24Miyachi, H. (2007). Successes and failures among porcelain trading firms in the early Meiji Period. Japanese Research in Business History 24: 97-116.
The Seymour Valley Archaeological Project. B Muckle, The Midden. 332Muckle, B. (2001). The Seymour Valley Archaeological Project. The Midden 33(2): 2-6.
Community archaeology in the Seymour Valley, British Columbia: a joint initiative of Capilano College and the Greater Vancouver Regional District. B Muckle, Teaching Anthropology: SACC Notes. 9136Muckle, B. (2002). Community archaeology in the Seymour Valley, British Columbia: a joint initiative of Capilano College and the Greater Vancouver Regional District. Teaching Anthropology: SACC Notes 9(1): 17, 36.
Archaeology of Nikkei logging camps in north Vancouver. B Muckle, Nikkei Images (National Nikkei Museum and Heritage Centre Newsletter). 9Muckle, B. (2004). Archaeology of Nikkei logging camps in north Vancouver. Nikkei Images (National Nikkei Museum and Heritage Centre Newsletter) 9(4): 1-3.
Excavating logging camps in the Seymour Valley: Capilano University. B Muckle, Archaeological Field School. The Midden. 413Muckle, B. (2009). Excavating logging camps in the Seymour Valley: Capilano University 2009 Archaeological Field School. The Midden 41(3): 4-5.
The Seymour Valley Community Archaeology Project. B Muckle, An Overview of Sites Investigated, the Artifact Collection. North Vancouver, BCCapilano UniversityMuckle, B. (2010). The Seymour Valley Community Archaeology Project, 2000-2010: An Overview of Sites Investigated, the Artifact Collection, Education, and Research. Capilano University, North Vancouver, BC.
Archaeology of a Japanese camp in the forests of north Vancouver: the 2013 Capilano University Archaeology Field School. B Muckle, The Midden. 452Muckle, B. (2013). Archaeology of a Japanese camp in the forests of north Vancouver: the 2013 Capilano University Archaeology Field School. The Midden 45(2): 5-7.
Archaeology of an early twentieth-century Nikkei camp in the Seymour Valley: a photo essay. B Muckle, BC Studies. 192Muckle, B. (2017). Archaeology of an early twentieth-century Nikkei camp in the Seymour Valley: a photo essay. BC Studies 192: 125-148.
Archaeology of two 20 th century Japanese Canadian sites in southwest British Columbia. Asian American Comparative Collection Newsletter. B Muckle, Supplement. 371Muckle, B. (2020). Archaeology of two 20 th century Japanese Canadian sites in southwest British Columbia. Asian American Comparative Collection Newsletter, Supplement 37(1): 5-6.
Asian Tz'u: porcelain for the American market. F W Mueller, Jr, Wong Ho Leun: An American Chinatown. San Diego, CA2Great Basin FoundationMueller, F. W., Jr. (1987). Asian Tz'u: porcelain for the American market. In Wong Ho Leun: An American Chinatown, Vol. 2, Great Basin Foundation, San Diego, CA, pp. 259-311.
Defining karst defenses: construction and features. J Mushynsky, Historical Archaeology. 53Mushynsky, J. (2019). Defining karst defenses: construction and features. Historical Archaeology 53: 193- 204.
The archaeology of World War II karst defences in the Pacific. J Mushynsky, J Mckinnon, F Camacho, Journal of Conflict Archaeology. 133Mushynsky, J., McKinnon, J., and Camacho, F. (2018). The archaeology of World War II karst defences in the Pacific. Journal of Conflict Archaeology 13(3): 198-222.
Archaeological Investigations at Kawainui Marsh, in the Kukaono Area. E Neller, Kailua, Oahu; Kapolei, HIState Historic Preservation OfficeNeller, E. (1982). Archaeological Investigations at Kawainui Marsh, in the Kukaono Area, Kailua, Oahu. State Historic Preservation Office, Kapolei, HI.
Altered Lives, Altered Environments: Creating Home at Manzanar Reocation Center. L W Ng, BostonUniversity of MassachusettsMaster's thesisNg, L. W. (2014). Altered Lives, Altered Environments: Creating Home at Manzanar Reocation Center, 1942- 1945. Master's thesis, University of Massachusetts, Boston.
Consumption in World War II Japanese American incarceration camps. L Ng, S L Camp, Leone, M. P. and Knauf, J. E.SpringerNew YorkHistorical Archaeologies of CapitalismNg, L. and Camp, S. L. (2015). Consumption in World War II Japanese American incarceration camps. In Leone, M. P. and Knauf, J. E. (eds.), Historical Archaeologies of Capitalism. Springer, New York, pp. 149-180.
Finding a Path Forward: Asian American Pacific Islander National Historic Landmarks Theme Study. F Odo, National Park Service, Washington, DCOdo, F. (2018). Finding a Path Forward: Asian American Pacific Islander National Historic Landmarks Theme Study. National Park Service, Washington, DC.
A study of Chinese ceramics excavated in Tucson. J W Olsen, The Kiva. 441Olsen, J. W. (1978). A study of Chinese ceramics excavated in Tucson. The Kiva 44(1): 1-50.
The development of the pottery industry: the case of the Tokoname Ceramic Industry. K Omori, Japanese Research in Business History. 21Omori. K. (2004). The development of the pottery industry: the case of the Tokoname Ceramic Industry. Japanese Research in Business History 21: 51-73.
Pre-war shipping markets and trading companies. H Oshima, Japanese Research in Business History. 28Oshima, H. (2011). Pre-war shipping markets and trading companies. Japanese Research in Business History 28: 85-103.
General trading companies in the interwar period: the expansion of Asia-Pacific trade and the progress of Japanese trading companies. H Oshima, Japanese Research in Business History. 30Oshima, H. (2013). General trading companies in the interwar period: the expansion of Asia-Pacific trade and the progress of Japanese trading companies. Japanese Research in Business History 30: 49-64.
The Archaeology of Gardens in Japanese American Incarceration Camps. K H Ozawa, San Francisco, CASan Francisco State UniversityMaster's thesisOzawa, K. H. (2016). The Archaeology of Gardens in Japanese American Incarceration Camps. Master's thesis, San Francisco State University, San Francisco, CA.
Cultural Resource Investigation for the Proposed Gresham Vista Business Park Multnomah County. K Paraso, R Campbell, D V Ellis, D Shannon, M Goodwin, T Ogle, D Gilmour, A Huff, Oregon. Willamette Cultural Resources Associates, Ltd. Paraso, K., Campbell, R., Ellis, D. V., Shannon, D., Goodwin, M., Ogle, T., Gilmour, D., and Huff, A. (2013). Cultural Resource Investigation for the Proposed Gresham Vista Business Park Multnomah County, Oregon. Willamette Cultural Resources Associates, Ltd., Portland, OR.
Second World War Japanese defences on Watom Island. P Petchey, Journal of Conflict Archaeology. 101Petchey, P. (2015). Second World War Japanese defences on Watom Island, Papua New Guinea. Journal of Conflict Archaeology 10(1): 29-51.
Peleliu 1944: the archaeology of a South Pacific D-Day. N Price, R Knecht, Journal of Conflict Archaeology. 71Price, N. and Knecht, R. (2012). Peleliu 1944: the archaeology of a South Pacific D-Day. Journal of Conflict Archaeology 7(1): 5-48.
After the typhoon: multicultural archaeologies of World War II on Peleliu. N Price, R Knecht, Journal of Conflict Archaeology. 83Price, N. and Knecht, R. (2013). After the typhoon: multicultural archaeologies of World War II on Peleliu, Palau, Micronesia. Journal of Conflict Archaeology 8(3): 193-248.
The Many Functions and Meanings of Flora within the Lives of Two American Immigrant Families. Master's thesis. E P Riggs, BinghamtonState University of New YorkRiggs, E. P. (2015). The Many Functions and Meanings of Flora within the Lives of Two American Immigrant Families. Master's thesis, State University of New York, Binghamton.
Identification and dating of Japanese glass beverage bottles. D E Ross, Technical Briefs in Historical Archaeology. 4Ross, D. E. (2009a). Identification and dating of Japanese glass beverage bottles. Technical Briefs in Historical Archaeology 4: 7-17.
Material Life and Socio-Cultural Transformation among Asian Transmigrants at a Fraser River Salmon Cannery. Doctoral dissertation. D E Ross, Burnaby, BCSimon Fraser UniversityRoss, D. E. (2009b). Material Life and Socio-Cultural Transformation among Asian Transmigrants at a Fraser River Salmon Cannery. Doctoral dissertation, Simon Fraser University, Burnaby, BC.
Comparing the material lives of Asian transmigrants through the lens of alcohol consumption. D E Ross, Journal of Social Archaeology. 102Ross, D. E. (2010). Comparing the material lives of Asian transmigrants through the lens of alcohol consumption. Journal of Social Archaeology 10(2): 230-254.
Factors influencing the dining habits of Japanese and Chinese migrants at a British Columbia salmon cannery. D E Ross, Historical Archaeology. 452Ross, D. E. (2011). Factors influencing the dining habits of Japanese and Chinese migrants at a British Columbia salmon cannery. Historical Archaeology 45(2): 68-96.
Late-nineteenth and early-twentieth-century Japanese domestic wares from British Columbia. D E Ross, Ceramics in America. Chipstone Foundation. Hunter, R.Fox Point, WIRoss, D. E. (2012a). Late-nineteenth and early-twentieth-century Japanese domestic wares from British Columbia. In Hunter, R. (ed.), Ceramics in America. Chipstone Foundation, Fox Point, WI, pp. 2-29.
Transnational artifacts: grappling with fluid material origins and identities in archaeological interpretations of culture change. D E Ross, Journal of Anthropological Archaeology. 311Ross, D. E. (2012b). Transnational artifacts: grappling with fluid material origins and identities in archaeo- logical interpretations of culture change. Journal of Anthropological Archaeology 31(1): 38-48.
The 2013 Simon Fraser University Field School on Don and Lion Islands. D E Ross, The SHA Newsletter. Gainesville. Ross, D. E.464University Press of FloridaAn Archaeology of Asian TransnationalismRoss, D. E. (2013). An Archaeology of Asian Transnationalism. University Press of Florida, Gainesville. Ross, D. E. (2014). The 2013 Simon Fraser University Field School on Don and Lion Islands, Richmond British Columbia. The SHA Newsletter 46(4): 12-15.
Archaeology of Asian labour migration at a Fraser River salmon cannery. D E Ross, Rousseau, M.Archaeology PressBurnaby, BCSimon Fraser UniversityArchaeology of the Lower Fraser River RegionRoss, D. E. (2017a). Archaeology of Asian labour migration at a Fraser River salmon cannery. In Rousseau, M. (ed.), Archaeology of the Lower Fraser River Region. Archaeology Press, Simon Fraser University, Burnaby, BC, pp. 201-208.
Archaeology of the Chinese and Japanese diasporas in North America and a framework for comparing the material lives of transnational migrant communities. D E Ross, Warner, M. and Purser, M.University of Nebraska PressLincolnHistorical Archaeology through a Western LensRoss, D. E. (2017b). Archaeology of the Chinese and Japanese diasporas in North America and a framework for comparing the material lives of transnational migrant communities. In Warner, M. and Purser, M. (eds.), Historical Archaeology through a Western Lens. University of Nebraska Press, Lincoln, pp. 174- 209.
Finding a Path Forward: Asian American Pacific Islander National Historic Landmarks Theme Study. US Government Printing Office. D E Ross, Odo, F.Washington, DCArchaeological research on Asian AmericansRoss, D. E. (2018). Archaeological research on Asian Americans. In Odo, F. (ed.), Finding a Path Forward: Asian American Pacific Islander National Historic Landmarks Theme Study. US Government Printing Office, Washington, DC, pp. 53-84.
Apology and commemoration memorializing the World War II Japanese American incarceration at the Tanforan Assembly Center. V Rozas-Krause, History and Memory. 302Rozas-Krause, V. (2018). Apology and commemoration memorializing the World War II Japanese American incarceration at the Tanforan Assembly Center. History and Memory 30(2): 40-78.
A bulwark in the Pacific: an example of World War II archaeology on Saipan. S Russell, M A Fleming, Wood, R.Museum of Anthropology, Department of Anthropology, University of Missouri-ColumbiaArchaeological Studies of World War IIRussell, S. and Fleming, M. A. (1991). A bulwark in the Pacific: an example of World War II archaeology on Saipan. In Wood, R. (ed.), Archaeological Studies of World War II. Museum of Anthropology, Department of Anthropology, University of Missouri-Columbia, pp. 13-28.
Inventory records of ceramics and opium from a nineteenth-century Chinese store in California. R A Sando, D L Felton, Hidden Heritage: Historical Archaeology of the Overseas Chinese. Wegars, P.Baywood, Amityville, NYSando, R. A. and Felton, D. L. (1993). Inventory records of ceramics and opium from a nineteenth-century Chinese store in California. In Wegars, P. (ed.), Hidden Heritage: Historical Archaeology of the Overseas Chinese. Baywood, Amityville, NY, pp. 151-76.
Recover of Additional Information from the Gila River Farms Expansion Area: A Study of a Japanese-American Relocation Center. M Sawyer-Lang, Archaeological Consulting Services, Ltd. Sawyer-Lang, M. (1988). Recover of Additional Information from the Gila River Farms Expansion Area: A Study of a Japanese-American Relocation Center. Archaeological Consulting Services, Ltd., Tempe, AZ.
A Pier Into the Past at Point Mugu: The History and Archaeology of a Japanese-American Sportfishing Resort. J Schaefer, W Mccawley, ASM Affiliates. Schaefer, J. and McCawley, W. (1999). A Pier Into the Past at Point Mugu: The History and Archaeology of a Japanese-American Sportfishing Resort. ASM Affiliates, Encinitas, CA.
Hanamono: Japanese Export Wares to the United States 1868-1921. Unpublished ms. D J Scheans, Portland, ORCeramic Analysis Laboratory, Portland State UniversityScheans, D. J. (1984). Hanamono: Japanese Export Wares to the United States 1868-1921. Unpublished ms., Ceramic Analysis Laboratory, Portland State University, Portland, OR.
Feminine Identity Confined: The Archaeology of Japanese Women at Amache, a World War II Internment Camp. D O Shew, Denver, COUniversity of DenverMaster's thesisShew, D. O. (2010). Feminine Identity Confined: The Archaeology of Japanese Women at Amache, a World War II Internment Camp. Master's thesis, University of Denver, Denver, CO.
Perseverance and prejudice: maintaining community in Amache, Colorado's World War II Japanese internment camp. D Shew, A E Kamp-Whittaker, Prisoners of War: Archaeology, Memory, and Heritage of 19 th -and 20 th -Century Mass Internment. Mytum, H. and Carr, G.New YorkSpringerShew, D. and Kamp-Whittaker, A. E. (2013). Perseverance and prejudice: maintaining community in Amache, Colorado's World War II Japanese internment camp. In Mytum, H. and Carr, G. (eds.), Prisoners of War: Archaeology, Memory, and Heritage of 19 th -and 20 th -Century Mass Internment. Springer, New York, pp. 303-317.
Archaeologies of Indigenous survivance and residence: navigating colonial and scholarly dualities. S W Silliman, Rethinking Colonial Pasts through Archaeology. Ferris, N., Harrison, R., Wilcox, M. V.OxfordOxford University PressSilliman, S. W. (2014). Archaeologies of Indigenous survivance and residence: navigating colonial and scholarly dualities. In Ferris, N., Harrison, R., Wilcox, M. V. (eds.), Rethinking Colonial Pasts through Archaeology. Oxford University Press, Oxford, pp. 57-75.
Confined Cuisine: An Archaeological and Historical Examination of Culinary Practices at Amache, Colorado's WWII Japanese Internment Camp. S A Skiles, Denver, COUniversity of DenverMaster's thesisSkiles, S. A. (2008). Confined Cuisine: An Archaeological and Historical Examination of Culinary Practices at Amache, Colorado's WWII Japanese Internment Camp. Master's thesis, University of Denver, Denver, CO.
When the foreign is not exotic: ceramics at Colorado's WWII Japanese internment camp. S A Skiles, B J Clark, Trade and Exchange: Archaeological Studies from History and Prehistory. Dillian, C. D. and White, C. L.New YorkSpringerSkiles, S. A. and Clark, B. J. (2010). When the foreign is not exotic: ceramics at Colorado's WWII Japanese internment camp. In Dillian, C. D. and White, C. L. (eds.), Trade and Exchange: Archaeological Studies from History and Prehistory. Springer, New York, pp. 179-192.
An Archaeological and Ethnographic Examination of the Presence, Acquisition, and Consumption of Sake at Camp Amache, a World War II Japanese Internment Camp. M A Slaughter, DenverUniversity of ColoradoMaster's thesisSlaughter, M. A. (2006). An Archaeological and Ethnographic Examination of the Presence, Acquisition, and Consumption of Sake at Camp Amache, a World War II Japanese Internment Camp. Master's thesis, University of Colorado, Denver.
An archaeological and ethnographic examination of the acquisition, presence, and consumption of saké at Camp Amache, a World War II Japanese internment camp. M A Slaughter, Prisoners of War: Archaeology, Memory, and Heritage of 19 th -and 20 th -Century Mass Internment. Mytum, H. and Carr, G.New YorkSpringerSlaughter, M. A. (2013). An archaeological and ethnographic examination of the acquisition, presence, and consumption of saké at Camp Amache, a World War II Japanese internment camp. In Mytum, H. and Carr, G. (eds.), Prisoners of War: Archaeology, Memory, and Heritage of 19 th -and 20 th -Century Mass Internment. Springer, New York, pp. 285-301.
Wrestling With Tradition: Japanese Activities at Amache, a World War II Incarceration Facility. Master's thesis. Z A Starke, Denver, COUniversity of DenverStarke, Z. A. (2015). Wrestling With Tradition: Japanese Activities at Amache, a World War II Incarceration Facility. Master's thesis, University of Denver, Denver, CO.
Sourcing and dating of Asian porcelains by elemental analysis. A Stenger, Hidden Heritage: Historical Archaeology of the Overseas Chinese. Wegars, P.Baywood, Amityville, NYStenger, A. (1993). Sourcing and dating of Asian porcelains by elemental analysis. In Wegars, P. (ed.), Hidden Heritage: Historical Archaeology of the Overseas Chinese. Baywood, Amityville, NY, pp. 315-331.
Mindful masquerades: que(e)rying Japanese ommigrant dress in turn-of-the-century San Francisco. A Sueyoshi, Frontiers. 263Sueyoshi, A. (2005). Mindful masquerades: que(e)rying Japanese ommigrant dress in turn-of-the-century San Francisco. Frontiers 26(3): 67-100.
An Archeological Survey of the Gila River Farms Expansion. M Sullivan, M Sawyer-Lang, R W Effland, Jr, M Green, Archaeological Consulting Services, Ltd. Sullivan, M., Sawyer-Lang, M., Effland, R. W., Jr., and Green, M. (1987). An Archeological Survey of the Gila River Farms Expansion, Pinal County, Arizona. Archaeological Consulting Services, Ltd., Tempe, AZ.
P Swader, An Analysis of Modified Material Culture from Amache: Investigating the Landscape of Japanese American Internment. Master's thesis. Denver, COUniversity of DenverSwader, P. (2015). An Analysis of Modified Material Culture from Amache: Investigating the Landscape of Japanese American Internment. Master's thesis, University of Denver, Denver, CO.
World War II artefacts and wartime use of caves in Guam. D Taborosi, J W Jenson, Mariana Islands. Capra. 4Taborosi, D. and Jenson, J. W. (2002). World War II artefacts and wartime use of caves in Guam, Mariana Islands. Capra 4, http://capra.group.shef.ac.uk/4/danko.html, accessed July, 2020.
Return to Butte Camp: A Japanese-American World War II Relocation Center. O Tamir, S C Russell, K Jackman Jensen, S Lerner, Archaeological Consulting Services, Ltd. Tamir, O., Russell, S. C., Jackman Jensen, K., and Lerner, S. (1993a). Return to Butte Camp: A Japanese- American World War II Relocation Center. Archaeological Consulting Services, Ltd., Tempe, AZ.
Supplemental Study of Butte Camp at the Rivers Relocation Center. O Tamir, S C Russell, Jackman Jensen, K , A Japanese-American World War II Relocation Center: Interim Report. Archaeological Consulting Services, Ltd. Tamir, O., Russell, S. C., and Jackman Jensen, K. (1993b). Supplemental Study of Butte Camp at the Rivers Relocation Center: A Japanese-American World War II Relocation Center: Interim Report. Archaeological Consulting Services, Ltd., Tempe, AZ.
Gardens below the watchtower: gardens and meaning in World War II Japanese American incarceration camps. A H Tamura, Landscape Journal. 23Tamura, A. H. (2004). Gardens below the watchtower: gardens and meaning in World War II Japanese American incarceration camps. Landscape Journal 23: 1-21.
The story of the Green Lake Gardens Company and the Kumasaka family. A Valentino, Archaeology in Washington. 17Valentino, A. (2017). The story of the Green Lake Gardens Company and the Kumasaka family. Archaeology in Washington 17: 102-120.
The Archaeology of the Japanese World War II Occupation of Christmas Island. Honors B.A. thesis. H Van Der Riet, PerthUniversity of Western AustraliaVan der Riet, H. (2018). The Archaeology of the Japanese World War II Occupation of Christmas Island. Honors B.A. thesis, University of Western Australia, Perth.
Data Synthesis in Labor and Life-Styles among San Diego's Working Class: Historical Archaeology at the Amerisuites Site by Jerry Schaefer and Sinéad Ní Ghabhláin. S R Van Wormer, Stephen Van Wormer, Susan D. Walter, and Ken MoslakASM Affiliates, IncCarlsbad, CaliforniaVan Wormer, S. R. (2009). Data Synthesis in Labor and Life-Styles among San Diego's Working Class: Historical Archaeology at the Amerisuites Site by Jerry Schaefer and Sinéad Ní Ghabhláin, with contributions by Stephen Van Wormer, Susan D. Walter, and Ken Moslak. ASM Affiliates, Inc., Carlsbad, California.
Archaeological Resource Management Corporation. S R Van Wormer, S D Walter, Mission Viejo, South Orange County, California; Anaheim, CAHistoric Artifact Analysis from CA-ORA-1301HVan Wormer, S. R. and Walter, S. D. (1993). Historic Artifact Analysis from CA-ORA-1301H, Mission Viejo, South Orange County, California. Archaeological Resource Management Corporation, Anaheim, CA.
Overseas Chinese archaeology: historical foundations, current reflections, and new directions. B L Voss, R Allen, Historical Archaeology. 423Voss, B. L. and Allen, R. (2008). Overseas Chinese archaeology: historical foundations, current reflections, and new directions. Historical Archaeology 42(3): 5-28.
Mark Walker, T M Van Bueren, D O Shew, M D Meyer, A Praetzellis, M Praetzellis, Nearly Neighbors: Archaeological Investigations for the High Street Seismic Retrofit Project in. Oakland, California; Rohnert Park, CASonoma State UniversityWalker, Mark, Van Bueren, T. M., Shew, D. O., Meyer, M. D., Praetzellis, A., and Praetzellis, M. (2012). Nearly Neighbors: Archaeological Investigations for the High Street Seismic Retrofit Project in Oakland, California. Anthropological Studies Center, Sonoma State University, Rohnert Park, CA.
Japanese Artifact Illustrations, Terminology, and Selected Bibliography, revised. P Wegars, Asian American Comparative CollectionMoscow, IDUniversity of IdahoWegars, P. (1999). Japanese Artifact Illustrations, Terminology, and Selected Bibliography, revised January 2006. Asian American Comparative Collection, University of Idaho, Moscow, ID.
The Asian American Comparative Collection: a unique resource for archaeologists and historians. P Wegars, Historical Archaeology. 423Wegars, P. (2008). The Asian American Comparative Collection: a unique resource for archaeologists and historians. Historical Archaeology 42(3): 166-170.
Imprisoned in Paradise: Japanese Internee Road Workers at the World War II Kooskia Internment Camp. P Wegars, Asian American Comparative Collection. Wegars, P. (2010). Imprisoned in Paradise: Japanese Internee Road Workers at the World War II Kooskia Internment Camp. Asian American Comparative Collection, Moscow, Idaho.
A Cultural Resource Survey of the Proposed Port Blakely Mill Company Development. J M Welch, R D Daugherty, Western Heritage IncOlympia, WAWelch, J. M. and Daugherty, R. D. (1993). A Cultural Resource Survey of the Proposed Port Blakely Mill Company Development. Western Heritage Inc., Olympia, WA.
Results of Data Recovery and Site Evaluation at the Japanese Gulch Site 45SN398. W A White, Iii, S A Boswell, C J Miss, Northwest Archaeological Associates, IncMukilteo, Washington; Seattle, WAWhite, W. A. III, Boswell, S. A., and Miss, C. J. (2009). Results of Data Recovery and Site Evaluation at the Japanese Gulch Site 45SN398, Mukilteo, Washington. Northwest Archaeological Associates, Inc., Seattle, WA.
Final Report for the Archaeological Impact Assessment of the South Courtenay Connector for the Vancouver Island Highway Project, Permit 1998-234. S Witt, Rick Howard Consulting Archaeologist. Witt, S. (1998). Final Report for the Archaeological Impact Assessment of the South Courtenay Connector for the Vancouver Island Highway Project, Permit 1998-234. Rick Howard Consulting Archaeologist, Langley, BC.
Results of Survey and Monitoring for the Proposed GRIC-DPW Installation of a Water Tank and a Water Main From Butte Camp to Preschool Road. D K Wright, Pinal County, Gila River Indian Community, Arizona; Sacaton, AZCultural Resource Management ProgramWright, D. K. (2010). Results of Survey and Monitoring for the Proposed GRIC-DPW Installation of a Water Tank and a Water Main From Butte Camp to Preschool Road, Pinal County, Gila River Indian Community, Arizona. Cultural Resource Management Program, Sacaton, AZ.
Japanese Americans in World War II: A National Historic Landmarks Theme Study. National Historic Landmarks Program. B Wyatt, National Park Service, Washington, DCWyatt, B. (ed.). (2012). Japanese Americans in World War II: A National Historic Landmarks Theme Study. National Historic Landmarks Program, National Park Service, Washington, DC.
The popularization of department stores and the system for creating trends (1910-1930). Y Yamauchi, Japanese Research in Business History. 31Yamauchi, Y. (2014). The popularization of department stores and the system for creating trends (1910-1930). Japanese Research in Business History 31: 47-66.
Results of the Archaeological Monitoring Program for the Restaurant Depot Project. C Zepeda-Herman, H Price, RECON Environmental, IncSan Diego, CAZepeda-Herman, C. and Price, H. (2012). Results of the Archaeological Monitoring Program for the Restaurant Depot Project. RECON Environmental, Inc., San Diego, CA.
Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
| [
-0.1076795905828476,
0.06495991349220276,
-0.058907076716423035,
0.08281323313713074,
0.023626796901226044,
-0.03934144973754883,
0.054979827255010605,
-0.06940055638551712,
-0.11191019415855408,
0.010617760941386223,
0.14441770315170288,
-0.05098208039999008,
0.0020803683437407017,
0.2718... |
CEEA-ACEG20) Conference CEEA-ACEG20; Paper 180 Concordia and McGill Universities
June 18 -21, 2019 -1 of 7
Nishant Balakrishnan
Centre for Engineering Professional Practice and Engineering Education
Faculty of Engineering
University of Manitoba
Rebecca Balakrishnan
Counselling Psychology
Department of Educational Administration, Foundations, and Psychology
Faculty of Education
University of Manitoba Nishant.Balakrishnan@UManitoba.ca
Rebecca.Balakrishnan@UManitoba.ca
CEEA-ACEG20) Conference CEEA-ACEG20; Paper 180 Concordia and McGill Universities
Proceedings 2020 Canadian Engineering Education Association
2020 Canadian Engineering Education AssociationJune 18 -21, 2019 -1 of 7Engineering DesignParadigms in DesignEngineering EducationCareer DevelopmentEngineering Portfolio
In a typical engineering classroom, there are many skills that students are expected to learn, develop and apply. Educators struggle on a regular basis to find meaningful ways to get students to develop skills. While it is possible to make large educational reforms in a program, sometimes change can be found in small and meaningful modifications to assessments. This paper focuses on simple, knowledge-based assessments used in accredited programs. An example is provided of a framework used in a second-year design course to transform simple assessments into opportunities for the development of deep skills, while at the same time managing educational resources and maintaining a focus on outcome-based assessment. The primary components of the framework are to tie in long term skills development, aspects of STEAM (specifically the arts elements), as well as aspects of career development and engineering identity into assignments, to allow students to contextualize their skill development into the broader understanding of their own career and identity development as an engineer.
INTRODUCTION
In engineering education, there is a major struggle that takes place in nearly every classroom, where instructors are challenged to ensure they are creating assessments that are: applied, reflective of practice or practical skills, and also meet specific assessment criteria for accreditation. Each of these requirements are in some conflict with each other as there are typical educational approaches to account for each one but there isn't necessarily a simple approach that can account for all of them. In many engineering programs, the simplest solution is to divide each of these approaches into discrete ideas, leading to specific assessments (such as basic assignments) where students are easily assessed on their learning outcomes (sometimes via simple summative feedback from a teaching assistant), and more complex assessments to capture some of these other aspects. This approach, while somewhat effective, has systematic problems that are not necessarily all that easy to solve. One example is that students often delineate skills as "textbook" or "assignment" skills from those that are more applied, due to the nature of splitting up assessments that way [1]. Students also tend to be more engaged when they are cognitively challenged, showcasing a willingness to go beyond basic assignment requirements on challenging projects as compared to simpler assessments [2] [3]. This is also exacerbated by the lack of educational resources that most instructors face, which typically results in educators focusing on the more complex assessments and in exchange needing to occasionally rely on some basic assessments.
This same struggle is, to some extent, also mirrored in industry and the professional skills engineers are expected to have when transitioning into the workplace [4]. Practicing engineers are often expected to be able to solve a diversity of problems, which itself is a dichotomy: students need the skills required to solve the problems, but also the situational ability to apply the knowledge they have learned in an applied setting, and also to be able to synthesize and create that same knowledge in the workplace. Educational literature speaks significantly about this, from looking at how education should move up Bloom's taxonomy [5], which is also mirrored in the CEAB's 12 graduate attributes in their "level of competence" required [6]. This often leads to students focusing on developing a basic understanding of skills in lower year courses and applying these skills more as they go through their degree program before reaching their "capstone" or equivalent upper year course. There have been many efforts to pull some of the application down to lower years [7] [8], however the efficacy of this approach relies on students retaining the knowledge they learn and being able to apply it in a progressively more applied manner. Much of educational literature however would typically indicate that unless a program is carefully sculpted this is, by nature, not the way students learn. Students require very specific scaffolding to support their learning processes to achieve this [9]. In the most specific case, developing skills at one level and relying on students to maintain and develop them is a fairly optimistic educational goal. To achieve that, an educational program would need to carefully scaffold those skills and ensure continual development is somehow maintained.
A further layer of this problem is finding the connection between what is being studied in school to the skills required by industry. There is debate about whether or not students are equipped for career success, with opinion pieces on one end of the spectrum claiming students do not have the basic skills required to succeed in the workforce upon graduation, while others argue that the issue is students simply do not understand how to effectively articulate the skills they do possess [10]. Research has shown that students do struggle to connect the skills they build in school to the skills required in the world of work [11]. One way students might learn to better articulate their skills is through opportunities to reflect on and connect their studies to employability skills [12]. This can in turn provide opportunities for meaningful career development. Reflection is a major component of the career development process, where individuals connect their experiences, skills, and other self-knowledge to their career goals [13]. By creating explicit connections between what is being studied in the classroom to the skills needed in the world of work, students might be better equipped to market themselves to employers in the future.
From all of these three problems, it can be seen that there is a commonality of elements, and a possible solution is to look at ways to inject elements of practicality, industry relevant engineering skills, and career development into assignment work, without creating extra educational overhead in the process. A way to address this is to look at an assignment (or assignment set) in a portion of a course that typically relies heavily on fairly basic outcome-based assessment, and transform the assessment into something that can capture more of these elements, but still use the same (or similar) evaluative framework. By tying in elements of lifelong learning associated with tasks that also develop awareness of employability skills and engineering identity, value can be given to work that students might not necessarily see as valuable.
Background
At the University of Manitoba, a pair of courses that draw heavily on practical and applied skills are the graphics derived second-year design courses offered in both the Mechanical and Biosystems Engineering programs. Both courses originally were conceived as introductory graphics courses, but both were transformed over years of development based on a simple idea: in order for students to learn computer aided design effectively, there has to be a mix of knowledge learning and experiential learning. As a result, the graphics content in both courses was reduced, while increasing the design content, but the end result was that students gained more mastery of the graphics content by needing to apply it regularly. Both courses involve heavy project work blended with a 15-hour graphics portion where students learn the basics of Computer Aided Design (CAD). Students learn design skills, while learning the CAD skills separately. Through project work and deliverables, they are tasked to apply those skills and get some exposure to the complexity of computer aided design in an applied setting. From an accreditation standpoint, both courses originally had a large amount of content related to the CEAB Engineering Tools graduate attribute, and shifting this work into design projects can prove to be challenging to some extent [7]. The approach for the course has been to always allocate some portion of the course assessment to purely graphics assignments to ensure students individually understood the content and were assessed on it. However, as many of the problems with this approach mirror those in the introduction to this paper, it leads to a simple idea: can these assignments be transformed into something that is more aligned with the course structure and in doing so can there be a benefit to student learning in a way that addresses some of these problems?
This paper will outline a case study of a framework that was developed to address these problems in context, with the eventual goal of being able to study the results more closely in a research study and also be able to inform new educational approaches for graphics education/assessment. The paper also covers the application of this framework in two courses to implement open ended design portfolios as assignments for students to help them develop needed skills, and apply them in an open-ended setting.
METHODOLOGY
One of the core tenants of the presented methodology is to look at the nature of the work that students do and how it develops their skills. In the case of outcome-based learning (as you would see in an accredited program), the principle of assessing students on specific ideas might not shift the focus of assessing students towards simpler assignments, but the assessment difficulty increases as educators drift away from simple assessments. This comes down to a simple notion: what minimum level of skill does a student need to exhibit in order to be deemed competent in that skill and also the related outcome? Likewise, how does one assess a student to ensure that skill is met? An illustrative example from a graphics perspective of this might be in blending in graphics with design. In a typical graphics assignment, a student might be given a tutorial on how to design a simple part, and be tasked to design a different or more challenging version once they finish. This assesses specific skills and the assessment process to ensure the student has developed the skills required is fairly basic. In a more applied assessment however, you might task the student to design a part to solve a problem or task, and then have them produce a CAD output of the same part. This now opens up the assignment, by incorporating a design aspect to it, but adds a level of complexity to the assessment from an educational standpoint: how do you ensure that the design is complex enough to use the skills you want, yet not scaffolded enough to be minimally different from the previous example? One solution to this is to perhaps come up with a set of carefully scaffolded assignments that let students engage in the content in a more applied sense, however this is not always easy to do in every course, and in the specific example of a graphics course takes a lot of careful scaffolding to do. This goes back to one of the basic points from the introduction that this can be seen as a somewhat trivial problem if educational resources are not finite, however if they are (as is most often the case) this is not a problem that is trivial to solve. This argument can also apply to more complex approaches such as those described in [7] and [8] that rely on blending skills into the design process to selectively evaluate them, however the additional resources required would also be quite challenging to justify for the outcome of a simple graphics skill assessment. Other solutions that rely purely on assessment alone, such as exams or more complex assignments, can also achieve a portion of the desired outcome (the evaluative end), but the application, and practical placement of these skills is critical, and these elements do not touch on those aspects of the skill development process necessarily.
Instead, a simple solution that can be used and that forms one of the two backbones of this framework is to get students to first develop skills and assess their competence in a fairly binary manner, but then allow them to demonstrate the skills in a more rich setting that allows for summative and formative feedback to be given at a point where it can be valued and developed by a student. To do this, students could be given a set of very simple assignments that might not even need to be given summative feedback, but are focused on formative feedback to develop the skills students need. After developing skills, students can work on more complex assignments like a portfolio (multi entry submission of one or more assignments to show competence and skill) or similar that showcases students' ability to apply skills while still allowing their learning to be tracked and allowing for the potential to have deeper meaning be developed by practicing skills in an applied context. Obviously, there are issues with this concept that need to be carefully addressed, but if it could be implemented it would present a viable solution to the situation given above.
While the form of this assessment is basic, a major component that is missing is a technique to motivate and engage students. Educational research tells us that students who are motived to learn (from either external or internal stimuli) are more engaged and more prepared to learn. This forms the second backbone to the framework: connecting the assessment to tangible outcomes valued by the student, thereby increasing students' perception of the value of the work they are doing. One way this can be done is to integrate the identity that students develop in the process of becoming engineers, into the assessments. This can be done by tying the skills they are learning into that identity and linking their learning to their skill development as a professional. Both of these are aspects strongly tied into motivation to learn [14]. By activating students' emerging engineering identity and the value they place in the development of skills for their career futures, we might be able to make students feel their assignments are more valuable.
Articulation of engineering skills
Engineering identity and engineering skills
Engineering identity is the personal and professional qualities defining who an engineer is and what they are capable of [15]. One component of engineering identity is the skills required for success in the profession [16]. Engineering students are engaged in a process of rapid skill expansion as they take the courses required to graduate from an accredited engineering program. But it is not always clear to students how these skills connect to their developing engineering identities or to their overall career goals. At times, educators might notice that students are not engaged in their assignments in a way that suggests they are attempting to grow their skills for their future, but rather they are trying to meet the minimum requirements amidst competing priorities. By positioning the skills developed in the class as relevant, meaningful skills required for career success, students have additional motivation to engage in skill-development beyond simply attempting to meet the minimum academic requirements of their course. Through this approach, the assignment is injected with further meaning in the context of their broader engineering skill development and can even be understood as a marketable example of their skills when searching for work [10].
Reflecting on and articulating skills through portfolio development
Portfolios are already being used as job search tools and have been integrated into engineering co-op programs and courses [17] [18]. By asking students to generate a portfolio of their work, students are given the opportunity to conceptualize their learning in the context of the labour market, which in turn provides the foundation for future communication of their skills to employers through resumes, cover letters, interviews, and during networking opportunities. Further, a portfolio can be referenced during the job search, providing tangible proof of a student's capabilities. By turning a basic assessment in a design heavy course into an opportunity for career development, Concordia and McGill Universities; June 18 -21, 2019 -4 of 7 -students are given a chance to take learning into their own hands and also develop their skills in an applied setting.
Course Implementation
To try out this approach in a classroom setting, two core courses at the University of Manitoba were used, one in Biosystems Engineering and one in Mechanical Engineering. Both are at a second-year level and are intensive project-based courses that apply design and engineering tools in a practical setting. Instead of focusing on the core content itself, the framework was targeted at the graphics assessment part of the course, which typically has a value of 10% of the course's final mark. Since the graphics portion primarily consists of basic assessments, the framework can be applied to these assessments to provide more depth of learning for students.
In past offerings of the course, the content had been set up so that: students attended graphics tutorials, did basic assignments on which they were given formative and summative feedback, and were given the option to redo the assignments based on feedback. By the end of the course, students were expected to have developed the skills they needed and the majority of students scored well because there was ample opportunity for development and feedback over the course. Students who received lower marks were not in this case typically students with lower abilities but those that did not for a variety of reasons want to rework or redo the assignments. Students were also asked to set up portfolios of their assignment work, with the intent of having them develop more unique work to put into the portfolios as their careers and degrees progressed. Unfortunately, it was informally noted that many students did not pick up their portfolios after submission, as many students informally viewed them as simple assessments that they typically had done well on. Over the years, the career and skill development aspect of a portfolio were also emphasized in class, but this was seen to make little difference in the performance of the students or their general view of the assignments.
To apply this approach to these courses a simple framework was developed and applied to the graphics assignment portion of the course alone. The hope was to see if some improvement could be seen by informing the approach used to assess students. The first step was looking at the typical errors students made in their course work. It was found that approximately 50% of the errors were made on minor details that involved adjusting minor elements to match what was required in the rubrics, and about 50% of the errors were from students who didn't understand how to perform specific skills being taught to a level required by the assessment. To address this, the framework utilized a similar assignment set as before, however the assignments were treated as skill development and converted from assignments that were given scale summative feedback to primarily formative feedback with a pass/fail grade. This greatly reduces the time required for teaching assistants to mark the assessments, which let them focus on the formative feedback and also allowed them to clearly identify students who needed help to bring them up to the required standard of skill. The deadlines for the assignments was shortened drastically, but students who needed help were also given more educational support.
These assessments were then set up as a gateway (i.e. a pass is required on each assignment to proceed) to the graphics assignment that was given to the students for both formative/summative assessment that was worth the full 10% of the grade. This assignment took the form of an open-ended design portfolio, which was a set of three entries that tied several aspects of design and engineering tools together. Students were expected to make three entries (approximately 4 pages each) that showcased a design that the student was responsible for, using the skills taught in the graphics portion. The entries were meant to be open ended, with students using graphics skills (CAD, renders, drawings) as well as communication skills and design skills to show how they made a specific part and what design processes and skills went into the process of making the part itself. The design and part also had to be a part the students themselves designed, which puts the onus on the student to make sure they at least have the experience of designing a few of the parts for their course projects.
There was also an emphasis placed on designs created for extra or co-curricular work. Of these entries (in the first iteration of the course) one could be something that the students designed on student teams or in other engagement beyond the classroom. This was based on tying in the identity development that students embed in work they do themselves and the perceived value in providing some credit for that work [14]. In later iterations of the framework this was increased to allow a student to submit all three entries based on content not directly designed for the course.
The assessment of the entries was done partially based on students' ability to use the skills required, but as these had been tested beforehand there was not a significant need to ensure that each skill is retested, but also partially on the: presentation, merit and nature of the designs and use of tools by the students. This allowed students to present designs that were very typical of the course (shafts, mechanisms, couplings they made to solve a problem) and also allowed students to present applications of the skills well outside of the realm of the course content (art displays, personal projects, co-curricular work, and work done during a work placement). All of these entries were marked by both the instructor and teaching assistants for the course with an emphasis from the teaching assistant side to ensure that the entries were using the desired graphics and communications skills, all of which had well established rubrics from the assignment portion.
The portfolio portion of the assignment allows students to explore more than what's covered in the course, Concordia and McGill Universities; June 18 -21, 2019 -5 of 7 -with some minor incentive to also positively engage with student's co-curricular and extra-curricular work that uses similar skills. This has been shown in the literature to bring value to the educational process [19] [20], however comes at the price of the potential for extra workload. As the framework was implemented, students had the option to treat the portfolio as another assignment, using the skills and tools used in class to describe parts they made in their projects for the same class with the extra potential learning being something that students could take on if they wished. This is commented on later, but typically students strongly preferred to do independent designs for at least a portion of their own portfolio.
The generalized version of the framework that can be applied in a variety of settings is two-fold.
Step one is to take a specific set of assignments, and decrease the level of overall assessment directly tied to them (while still keeping an incentive for students to complete them).
Step two is to create another assessment that mirrors the skills developed in the assignments and at its most basic can represent something that is as simple as the assessed content, but is broad and open enough to allow students to apply content beyond what is covered in the course. In doing this, students have the opportunity to create a unique portfolio of their own skills both within and beyond the course. The function of this is to apply the skills developed within the course to areas personally relevant to students and therefore more personally important to their own interests, goals, and engineering identity.
OUTCOMES AND RESPONSE
As of writing, three iterations of the discussed design courses have used the framework to have semi-open design portfolios. The overall results from an educational perspective have been very positive, with the course consuming the same resources needed from TA's to provide student feedback, while at the same time allowing focus to be put on developing skills where students need them. Students engaged in portfolio work have also been able to engage with a number of industries, other members of the faculty and have had the opportunity to expand their learning in a very meaningful manner. Multiple employers and other stakeholders have provided informal feedback indicating the appreciation for the design portfolios as a tool used to express a student's personal design accomplishments.
Student Perspectives
Students who were given the new open portfolio assignment seemed to have positive reactions overall. It was viewed as a chance to bring a more personalized touch to their education, but in a manner that is still optional to engage in. While there were students who used only inclass parts, some found that the in-class designed parts were not necessarily complex enough to easily do a portfolio entry about without going into significant technical detail. In many cases, students embarked on entirely independent small designs, devices like mechanical pencil bodies, phone mounts and similar practical designs with some personal resonance, while still meeting the requirements of the portfolio. This is to some extent heavily supported in the product development and design portion of the course, but also shows that students are willing to sometimes put in more than the bare minimum effort on what is replacing a simple assignment. In other cases, students were able to get credit for their cocurricular work, such as work on student design teams that goes well above and beyond the graphics requirements in the course. Overall, the perspective given from students was that the openness of the assessment was seen as a positive item.
In terms of career development and engineering identity, students leaving the class now had an artifact of their own personal skills. This artifact in turn could be utilized in future engagement in the labour market, informing skill articulation in resumes and cover letters and generating relevant stories for interviews. These portfolios can even be shared in conversation with potential employers, allowing the students to showcase their unique engineering designs and achievements.
One of the notable outcomes is actually reflected in the title to the paper, where the original framework doesn't necessarily heavily rely on Science Technology Engineering Arts and Math (STEAM) education. In a very simple sense however, the framework presented reflects applying these aspects to a basic assignment, developing something more diverse for students to explore and learn with. A major response from students was the positive engagement with the arts aspects of design and graphical communication, where the open nature of the artistic portion of this type of assessment brought value to the other elements that are typically part of technical engineering identity (the STEM portion of STEAM). The informal feedback given strongly indicated that the artistic side of design is something that many students resonate with but is not typically something that forms a backbone of what people view as traditional engineering identity [15].
FUTURE WORK AND SUGGESTIONS
As this is meant to be a work to inform practice, and the informal feedback has indicated that the application of the framework in the courses discussed is fairly successful, a follow-up qualitative study is suggested. This study would look at the experiences of students in second year courses and how alternate assessment frameworks influence students' motivation and understanding of their skill development.
As the portfolio aspect and career development portion of the framework are largely based on informal feedback and theory, a longitudinal study is being planned to explore some of the potential career and identity outcomes of the frameworks used in courses. The design portfolio developed by students can be a key entryway into building a students engineering identity, since it allows students to bring their personal interests into the context of their engineering education. Further, this portfolio also provides a record of tangible employability skills useful to the students' broader career, with the hope that students can begin to better connect their education to their longer term career goals in engineering.
Suggestions and Plans for Expansion
This framework, while in this context is primarily developed for a specific design course, has many applications in other courses were specific skills are taught that students are expected to develop over time on their own. In one example, this framework was also used to inform changes to a professional practice course at the University of Manitoba to create an applied project in a course that typically relies entirely on traditionally simple assessments.
Similar expansion could easily be done into courses in areas like writing, programming, and design, which are all skillsets we want students to develop but often have to also assess and evaluate in fairly specific ways. While these are all topics that could be easily developed with more educational resources, they are all also topics that typically have small assessments tied to them that the framework can be applied to.
Beyond this, educators could also introduce career language into their classrooms, naming the employable skills being developed. This could also highlight opportunities for Faculty to collaborate with Career Services and Co-Op staff to support students in understanding how their assignments can be translated into marketable skills. Overall, by introducing assessments which feel applicable to the real world, students can more easily attach their learning to their career goals.
CONCLUSIONS
Based on the outcomes of the framework being applied to a design course, it is clear that there are many opportunities to look at transforming aspects of courses and assessments to be more than just basic assessments and turn them instead into opportunities for students to express some of their deeper learning. While it is often the case in engineering programs that there is a lot of emphasis placed on the more practical skills, there is a need for many of the more basic skills in students to be developed. It is in those cases that frameworks like this or other pedagogical approaches may provide a better learning experience for students. When this framework was applied in a design course, the outcome not only managed to keep the form of the course relatively consistent, but also kept the overall amount of teaching capital required relatively similar as well. While it is not the most overwhelming finding, the nature of the approach was able to make a noticeable change with only a minor rework to the course layout/content itself, which on its own holds merit.
AcknowledgementsThe authors would like to thank M. Friesen (and the NSERC Chairs in Design Engineering on Enhanced Design Integration) and the Centre for Engineering Professional Practice for their support of developments in engineering pedagogy and research. They would also like to thank the Mechanical Engineering Department and Biosystems Engineering Department for the flexibility to implement the framework in courses that are core courses.
Active learning increases student performance in science, engineering, and mathematic. S Freeman, S L Eddy, M Mcdonough, M K Smith, N Okoroafor, H Jordt, & M P Wenderoth, Proceedings of the National Academy of Sciences. 11123S. Freeman, S. L. Eddy, M. McDonough, M. K. Smith, N. Okoroafor, H. Jordt, & M. P. Wenderoth, "Active learning increases student performance in science, engineering, and mathematic," Proceedings of the National Academy of Sciences, vol. 111, no. 23, pp. 8410-8415, 2014.
Student Engagement Literature Review. York: The Higher Education Academy. V Trowler, V. Trowler, Student Engagement Literature Review. York: The Higher Education Academy, 2010.
An Affective-Cognitive Teaching and Learning Approach for Enhanced Behavioural Engagements among Engineering Students. T A Lashari, M Alias, M J A Kesot & Z, Akasah, Engineering Education. 82T. A. Lashari, M. Alias, M. J. Kesot & Z. A. Akasah, "An Affective-Cognitive Teaching and Learning Approach for Enhanced Behavioural Engagements among Engineering Students," Engineering Education, vol. 8, no. 2, pp. 65-78, 2013.
Industry perceptions of graduate attribute requirements for the workplace. D S Petkau, Proceedings of the 2nd Annual CEEA Conference. the 2nd Annual CEEA ConferenceD. S. Petkau, "Industry perceptions of graduate attribute requirements for the workplace," Proceedings of the 2nd Annual CEEA Conference, no. 79, pp. 1-6, 2015.
A taxonomy for learning, teaching, and assessing: A revision of Bloom's Taxonomy of educational objectives. L W Anderson, D R Krathwohl, & B S Bloom, LongmanNew YorkL. W. Anderson, D. R. Krathwohl, & B. S. Bloom, A taxonomy for learning, teaching, and assessing: A revision of Bloom's Taxonomy of educational objectives, New York: Longman, 2001.
Determining the relative importance of the CEAB graduate attributes for engineering: An exploratory case study at the University of Manitoba. J Seniuk Cicek, Doctoral dissertation. University of ManitobaJ. Seniuk Cicek, "Determining the relative importance of the CEAB graduate attributes for engineering: An exploratory case study at the University of Manitoba," Doctoral dissertation, University of Manitoba, 2017.
Developing a framework to evaluate individual learning in engineering design problemspart 1: Teaching through simulacra of real-world problems. N Balakrishnan, Proceedings 2019 Canadian Engineering Education Association Conference. 2019 Canadian Engineering Education Association Conference1N. Balakrishnan, "Developing a framework to evaluate individual learning in engineering design problems - part 1: Teaching through simulacra of real-world problems," Proceedings 2019 Canadian Engineering Education Association Conference, vol. 1, pp. 1-5, 2019.
Developing a framework to evaluate individual learning in engineering design problemspart 2: Assessment of individual learning in team environments. N Balakrishnan, Proceedings 2019 Canadian Engineering Education Association Conference. 2019 Canadian Engineering Education Association Conference1N. Balakrishnan, "Developing a framework to evaluate individual learning in engineering design problems - part 2: Assessment of individual learning in team environments," Proceedings 2019 Canadian Engineering Education Association Conference, vol. 1, pp. 1-6, 2019.
Instructional Scaffolding in STEM Education Strategies and Efficacy Evidence. B Belland, Springer International PublishingChamB. Belland, Instructional Scaffolding in STEM Education Strategies and Efficacy Evidence, Cham: Springer International Publishing, 2017.
Driving academic quality: Lessons from Ontario's skills assessment projects. T J Pretti, & A Fannon, F. Deller, J. Pichette, & E. K. WatkinsToronto, ONSkills articulation and work integrated learningT. J. Pretti & A. Fannon, Skills articulation and work integrated learning. In F. Deller, J. Pichette, & E. K. Watkins (Eds.), Driving academic quality: Lessons from Ontario's skills assessment projects, pp. 81-92. Toronto, ON, 2018.
Psychology majors' understanding of skills-based learning outcomes. T S Martini, R Judges, & K Belicki, Scholarship of Teaching and Learning in Psychology. 12T. S. Martini, R. Judges, & K. Belicki, "Psychology majors' understanding of skills-based learning outcomes," Scholarship of Teaching and Learning in Psychology, vol. 1, no. 2, pp. 113-124, 2015.
Lost in Translation: Preparing Students to Articulate the Meaning of a College Degree. L Durose, & M Stebleton, Journal of College and Character. 174L. Durose & M. Stebleton, "Lost in Translation: Preparing Students to Articulate the Meaning of a College Degree," Journal of College and Character, vol. 17 no. 4, pp. 271-277, 2016.
Career planning, knowledge, and skills. K Mckinnon, & K Johnston, Career development practice in Canada: Perspectives, principles, and professionalism. B. Shepard & P.S. ManiToronto, ONCERICK. McKinnon & K. Johnston, Career planning, knowledge, and skills. In B. Shepard & P.S. Mani (Eds.), Career development practice in Canada: Perspectives, principles, and professionalism, Toronto, ON: CERIC, pp 173-198, 2014.
Threshold concepts in undergraduate engineering: Exploring engineering roles and value of learning. S Male, & D Bennett, Australasian Journal of Engineering Education. 201S. Male & D. Bennett, D, "Threshold concepts in undergraduate engineering: Exploring engineering roles and value of learning," Australasian Journal of Engineering Education, vol. 20 no. 1, pp. 59-69, 2015.
Engineering identities, epistemologies and values engineering education and practice in context. M Murphy, S Chance, & E Conlon, ; S Christensen, C Didier, A Jamison, M Meganck, & B Mitcham, Newberry, Springer International Publishing2ChamDesigning the identities of engineersM. Murphy, S. Chance, & E. Conlon, "Designing the identities of engineers," in S. Christensen, C. Didier, A. Jamison, M. Meganck, C Mitcham, & B. Newberry, Engineering identities, epistemologies and values engineering education and practice in context (Volume 2). Cham: Springer International Publishing, 2015.
A systematic literature review of engineering identity: definitions, factors, and interventions affecting development, and means of measurement. J Morelock, European Journal of Engineering Education. 426J. Morelock, "A systematic literature review of engineering identity: definitions, factors, and interventions affecting development, and means of measurement," European Journal of Engineering Education, vol. 42 no. 6, pp. 1240-1262, 2017.
Implementing a CEAB engineering graduate attributes based co-op work term curriculum. A M Coolen, Proceedings of the 2nd Annual CEEA Conference. the 2nd Annual CEEA ConferenceA. M. Coolen, "Implementing a CEAB engineering graduate attributes based co-op work term curriculum," Proceedings of the 2nd Annual CEEA Conference, 2011.
Teaching and assessing graduate attributes in cooperative education. D Spracklin-Reid, Proceedings of the 2014 Canadian Engineering Education Association (CEEA14) Conference. the 2014 Canadian Engineering Education Association (CEEA14) Conference63D. Spracklin-Reid, "Teaching and assessing graduate attributes in cooperative education," Proceedings of the 2014 Canadian Engineering Education Association (CEEA14) Conference, vol. 63, no. 1, 2014.
Experiential learning in engineering education: The role of student design competitions and a case study. M Gadola, & D Chindamo, International Journal of Mechanical Engineering Education. 471M. Gadola, & D. Chindamo, "Experiential learning in engineering education: The role of student design competitions and a case study," International Journal of Mechanical Engineering Education, vol. 47, no. 1, pp. 3-22, 2017
How service learning affects students. A Astin, L Vogelgesang, E Ikeda, J Yee, Higher Education Research Institute, UCLAA. Astin, L. Vogelgesang, E. Ikeda, and J.Yee, How service learning affects students. Higher Education Research Institute, UCLA, 2000.
| [
-0.07971466332674026,
0.06113085150718689,
0.09606572985649109,
0.10209740698337555,
-0.04693693667650223,
0.004051197320222855,
0.003641420044004917,
0.03551430255174637,
0.0060246530920267105,
0.06612034887075424,
-0.11836536228656769,
-0.11573540419340134,
0.03644660860300064,
0.0523638... |
The Pharma Innovation Journal 2020; SP-9(4): 36-38 Alterations in serum constituents of different duck varieties of Assam in healthy and duck plague out break
D J Kalita
Department of Veterinary Biochemistry
College of Veterinary Science
Assam Agricultural University Khanapara
GuwahatiAssamIndia
J Barkakati
Bezbaruah Department of Veterinary Biochemistry
College of Veterinary Science
Department of Veterinary Biochemistry
College of Veterinary Science
Assam Agricultural University Khanapara
GuwahatiAssamIndia
D J Kalita
Department of Veterinary Biochemistry
College of Veterinary Science
Assam Agricultural University Khanapara
GuwahatiAssamIndia
D J Kalita
Assam Agricultural University Khanapara
GuwahatiAssamIndia
N Bezbaruah
Assam Agricultural University Khanapara
GuwahatiAssamIndia
J Barkakati
Assam Agricultural University Khanapara
GuwahatiAssamIndia
The Pharma Innovation Journal 2020; SP-9(4): 36-38 Alterations in serum constituents of different duck varieties of Assam in healthy and duck plague out break
10.22271/tpi.2020.v9.i4Sb.4698Received: 02-02-2020 Accepted: 04-03-2020~ 36 ~Serum ConstituentsDuck PlagueDuckHealth Status
Alterations of serum constituents in three different varieties of duck namely Pati, Khaki Campbell and Nageswari from different parts of the state were evaluated in healthy and duck plague outbreak. A significant reduction (P<0.05) in protein and albumin level was observed in all the varieties of ducks under study during disease than that of the healthy ducks. A significant rise (P<0.05) in the level of globulin was recorded during duck plague outbreak in Pati and Nageswari breed of ducks. An increased level of glucose (162.35±9.45 mg/ dl) was recorded in Pati duck group during disease outbreak which differed significantly (P<0.05) from the healthy group (145.69±10.12 mg/dl). The healthy and the diseased group of Khaki Campbell showed glucose level of (159.78±9.23 mg/dl) and (172.95±8.21 mg/dl) respectively. The level of glucose in healthy and diseased group of Nageshwari variety of duck was recorded 171.62±7.63 and 185.11±5.6 mg/dl respectively. A significant (P<0.05) rise in blood urea nitrogen level of diseased Pati duck (1.95±0.15 mg/ 100 ml) was recorded as compared to the healthy group of Pati duck (1.27±0.06 mg/100 ml).
Introduction
Among all the poultry species, ducks are mostly preferred across the globe for their table egg production next to chickens. According to the (19 th ) Livestock census of Govt. of India, the ducks constitute about 3% (23.539 millions) of total poultry (729.2 million), in India (GOI, 2012) [8] . The Pati duck population constitutes a major indigenous non-descript duck variety in the state of Assam, India. The Annual egg production per duck (Pati) is 70-95 eggs, (Kalita et al., 2009) [10] . Generally Ducks are more disease resistance than poultry. In duck rearing the diseases of importance are duck plague, pasteurellosis and aflatoxicosis. The agro-climatic condition with marshy and waterlogged areas prevailing throughout the state provides a very congenial environment for rearing ducks in Assam (Kalita et al., 2009 [10] ; Deka et al., 2014 [6] ). Serum constituents of ducks provide valuable information for evaluation of health status, immunity which reflects many metabolic alterations of organs and tissues. However, available reports on serum biochemistry of these three varieties of ducks are scarce, as compared to other avian species. Comparative studies of serum biochemistry in chicken verses ducks are limited (Franco et al., 2010 [7] ; Kabir, 2012 [9] ). Biochemical parameters in indigenous ducks in various regions of the world differ from each other. It is important to investigate and create baseline information on serum biochemical profiles of the indigenous ducks locally for accurate interpretation of health status. Keeping this in view, the present investigation was carried out to study the alterations in serum biochemical profile in indigenous duck breeds of Assam under healthy and disease conditions.
Materials and Method
In the present study, 300 blood samples (5ml) from different varieties of duck namely Pati (150), Khaki Campbell (100) and Nageswari (100) were collected from different parts of the state from healthy as well during duck plague outbreak. Blood samples were collected from the wing veins of each bird under aseptic conditions. For estimation of the biochemical constituents, the blood was collected in sterile test tube without adding any anticoagulant and was left undisturbed in slanting position for 2-4 hours for serum separation. The separated ~ 37 ~ The Pharma Innovation Journal http://www.thepharmajournal.com serum samples were cleared by centrifugation at 3000 rpm for 5 minutes. After the serum was separated, it was kept in plastic vials and stored in deep freeze at -20 ºC until analysis. Different biochemical parameters namely total protein, albumin, globulin, glucose, blood urea nitrogen and uric acid were estimated using commercially available kit procured from Invitro Diagnostic Kits manufactured by Span Diagnostic Limited (Autospan Liquid Gold), GIDC, Sachin-394 230 (Surat), Gujarat, India. Data generated from the study were analyzed statistically (Snedecor and Cochran, 1994) [17] .
Result and discussions
The value of the serum constituents (Mean± S.E) of different varieties of duck of Assam in healthy and duck plague outbreak of the present investigation is presented in table 1.
Analysis of different biochemical profile in animals allow diagnosis of the subclinical symptom (Kaneko et al. 2009) [12] .
In the present investigation, serum constituents of healthy Pati duck, Khaki Campbell and Nageswari ducks were estimated and compared with the same variety of ducks in duck plague outbreak. A significant reduction (P<0.05) in total protein and albumin level was observed in all the varieties of ducks under study during duck plague outbreak than that of the healthy ducks. The hypoproteinemia and hypoalbuminemia might be attributed primarily due to liver dysfunction associated with duck virus hepatitis infection, decreased feed intake and also disturbed overall metabolism (Lin et al., 2011 andAhmed et al., 1975) [14,1] . Albumin, which is synthesized only in the liver, is mainly responsible for maintaining the oncotic blood pressure. Decrease albumin concentration recorded in the present experiment during disease outbreak might be due to hepatic insufficiency, malnutrition and gastrointestinal disturbances (Meyer et al.,1995) [15] .Significant decrease in the total serum protein and albumin in unhealthy birds could be due to severe damage to liver and kidney which result in failure of synthesis of plasma protein and protein loss respectively (Coles, 1986 ) [4] Fall in total plasma protein in diseases birds might be due to acute stress that leads to cortisol secretion and catabolism of protein (Kaneko et al., 1997) [11] . A significant rise (P<0.05) in the level of globulin was recorded during disease outbreak in all the three varieties of ducks. Globulin level of healthy Pati duck variety was found to be 1.79±0.10 g / dl whereas during disease outbreak the level recorded was 1.94±0.09 g/dl. Hyperglobulinemia is associated with chronic diseases and bacterial septicaemia (Coles, 1986) [4] . Butler (1971) [3] also reported an increase in serum globulin level which might be due to an enhanced synthesis of immunoglobulins. An increased level of glucose (162.35±9.45 mg/ dl) was recorded in Pati duck during disease outbreak which differed significantly (P<0.05) from that of healthy group (145.69±10.12 mg/dl). The healthy and the diseased group of Khaki Campbell showed glucose level of (159.78±9.23 mg/dl) and (172.95±8.21 mg/dl) respectively. These findings are in accordance with the results of Daugherty and Herrick (1952) [5] who also reported significant rise in plasma glucose level to in a group of disease birds that might be due to increased glycogenolysis caused by stress induced release of adreno-corticoid leading to acute hyperglycemia. These results also corroborated with the findings of Kumar and Rawat (1975) [13] . Low feed intake during acute infective stage may lead to secretion of adrenal corticosteroids promoting glycogenolysis (Patra et al., 2010) [16] .The level of glucose in healthy (171.62±7.63 mg/dl) and diseased group (185.11±5.6 mg/dl) of Nageswari differed significantly (P<0.05). The variation blood glucose concentration among the three groups of duck might be due to the genetic composition, hormonal level and availability of feed access. There was no significant variation in the level of uric acid in all the three varieties of birds under study during healthy and disease outbreak. A significant (P<0.05) rise in blood urea nitrogen (BUN) was observed in all three varieties of duck during disease outbreak as compared to the healthy groups. The elevation of blood urea nitrogen (BUN) might be due increased gluconeogenesis as well as well increase protein catabolism (Bell, 1971) [2] . From the present study it can be concluded that, there is a rise and fall of several biochemical parameters in response to disease in duck which can act as an indicator of the health status of duck. Considering the importance of ducks, further studies are warranted in this area to interpret the variation and fluctuations in serum biochemistry in response to different diseases.
AcknowledgementsThe authors are highly thankful to the Department of Biotechnology, Govt. of India for financial assistance to carry out this work.
Effect of experimental Duck Virus Hepatitis infection on some biochemical constituents and enzymes in the serum of White Pekin Ducklings. A Ahmed, Y Z El-Abdin, S Hamza, F E Saad, Avian Dis. 192Ahmed A, El-Abdin YZ, Hamza S, Saad FE. Effect of experimental Duck Virus Hepatitis infection on some biochemical constituents and enzymes in the serum of White Pekin Ducklings. Avian Dis. 1975; 19(2):305-10.
Plasma glucose. In: Physiology and Biochemistry of the Domestic Fowl. D J Bell, Bell, DJBell DJ. Plasma glucose. In: Physiology and Biochemistry of the Domestic Fowl. Edited by Bell, DJ
. B M Freeman, New London, York, Academic Press2915Freeman, BM. London and New York, Academic Press. 1971; 2:915.
Plasma Proteins. E J Butler, Physiology and Biochemistry of the Domestic Fowl. Bell, D.J. and Freeman, B.M. London and New YorkAcademic Press2Butler EJ. Plasma Proteins. In: Physiology and Biochemistry of the Domestic Fowl. Edited by Bell, D.J. and Freeman, B.M. London and New York, Academic Press. 1971; 2:933-961.
Coles EH Veterinary clinical pathology. The Pharma Innovation Journal. 38Coles EH Veterinary clinical pathology, edn 4.W.B. ~ 38 ~ The Pharma Innovation Journal http://www.thepharmajournal.com
. Saunders Company, Philadelphia, 486Saunders Company, Philadelphia, 1986, 486.
Caecal coccidiosis and carbohydrate metabolism in chickens. J W Daugherty, C A Herrick, J Parasitol. 38Daugherty JW, Herrick CA. Caecal coccidiosis and carbohydrate metabolism in chickens. J Parasitol. 1952; 38:298-304.
Improvement of rural livelihood through rearing of Chara-Chemballi ducks in Assam. World's Poultry Sc. R J Deka, Amm Zakir, R B Kayastha, J. 702Deka RJ, Zakir AMM, Kayastha RB. Improvement of rural livelihood through rearing of Chara-Chemballi ducks in Assam. World's Poultry Sc. J. 2014; 70(2):397- 404.
Comparison of biochemical values of paired serum and plasma samples from American Flamingos (Phoenicopterus ruber), Indian Runner ducks (Anas platyrhynchos) and Hyacinth Macaws (Anodorhynchus hyacinthinus). K H Franco, J P Hoover, K A Backues, M E Payton, Journal of Exotic Pet Medicine. 192Franco KH, Hoover JP, Backues KA, Payton ME. Comparison of biochemical values of paired serum and plasma samples from American Flamingos (Phoenicopterus ruber), Indian Runner ducks (Anas platyrhynchos) and Hyacinth Macaws (Anodorhynchus hyacinthinus). Journal of Exotic Pet Medicine. 2010; 19(2):169-176.
Ministry of Agriculture, Department of Animal Husbandry, Dairying and Fisheries. New DelhiGOI. 19th Livestock census, All India reportGOI. 19th Livestock census, All India report, New Delhi, Ministry of Agriculture, Department of Animal Husbandry, Dairying and Fisheries, 2012.
Serological analyses in chicken and other Birds. Crown Research in Education. M A Kabir, 2Kabir MA. Serological analyses in chicken and other Birds. Crown Research in Education. 2012; 2(5):181-183.
Present status of duck farming in Assam. N Kalita, N Barua, J Bhuyan, B L Chidananda, Proceeding of IV world waterfowl conference. eeding of IV world waterfowl conferenceThrissur, KeralaKalita N, Barua N, Bhuyan J, Chidananda BL. Present status of duck farming in Assam. In: Proceeding of IV world waterfowl conference. Thrissur, Kerala: India, 2009, 359-363.
. J J Kaneko, J W Harvey, M L Bruss, Clinical Biochemistry of Domestic Animals. Academic Press5th ed.Kaneko JJ. Harvey JW. Bruss ML. Clinical Biochemistry of Domestic Animals. 5th ed. Academic Press, California, USA, 1997.
Clinical biochemistry of domestic animals, edn. J J Kaneko, J W Harvey, M L Bruss, Academic Press6916New YorkKaneko JJ, Harvey JW, Bruss ML. Clinical biochemistry of domestic animals, edn, 6, Academic Press, New York, 2009, 916.
A note on effect of coccidiosis on serum enzymes, blood glucose and cholesterol in chicken. A Kumar, J S Rawat, Indian J Anim. Sci. 45Kumar A, Rawat JS. A note on effect of coccidiosis on serum enzymes, blood glucose and cholesterol in chicken. Indian J Anim. Sci. 1975; 45:154-156.
Immunosuppression effect of co-infection with MDRV and H9 AIV on thymus in muscovy ducks. F Lin, C Gao, S Chen, X Zhu, X Cheng, S Wang, Wei Sheng Wu Xue Bao. 51Lin F, Gao C, Chen S, Zhu X, Cheng X, Wang S. Immunosuppression effect of co-infection with MDRV and H9 AIV on thymus in muscovy ducks. Wei Sheng Wu Xue Bao. 2011; 51:1407-1412.
. D J Meyer, E H Coles, L J Rich, Medicina De Laboratório, Veterinária, 307São Paulo; RocaMeyer DJ, Coles EH, Rich LJ. Medicina de Laboratório Veterinária. São Paulo: Roca, 1995, 307.
PCR Based Diagnosis of Eimeria tenella Infection in Broiler Chicken. G Patra, Khan Md, Ayub Ali, Chanu, Jonathan Victoria, Int. J Poultry Sci. 98Patra G, Khan Md, Ayub Ali, Chanu, Victoria, Jonathan, et al. PCR Based Diagnosis of Eimeria tenella Infection in Broiler Chicken. Int. J Poultry Sci. 2010; 9(8):813- 818.
G W Snedecor, W G Cochran, Statistical Methods. AmesIowa State University Presseighth editionSnedecor GW, Cochran WG. Statistical Methods (eighth edition), Ames: Iowa State University Press, 1994.
| [
0.007883787155151367,
-0.01726776733994484,
-0.032288432121276855,
0.00401674211025238,
0.030874164775013924,
0.06118498742580414,
0.0785524994134903,
0.10956574976444244,
-0.002198876114562154,
0.069012351334095,
-0.02709716185927391,
-0.046887751668691635,
0.029725927859544754,
0.0362721... |
Jan 2022
Reactions 1888
Jan 202210.1002/pmrj.12735S COVID-19-vaccine Parsonage-Turner syndrome: case report
A man [age not stated] developed Parsonage-Turner syndrome following administration of COVID-19 vaccine [route and dosage not stated].The man presented to hospital with a 1-month history of severe left shoulder pain and weakness. The pain lasted for 2 weeks with persistent weakness. Ten days previously, he had received first dose of COVID-19 vaccine. On examination, he had 4/5 in left shoulder abduction and 3/5 external rotation strength, along with scapular dyskinesis and left infraspinous fossa atrophy. Two months after the symptom onset, an electrodiagnostic examination showed mononeuritis multiplex, involving the suprascapular and anterior interosseous nerve, along with abnormal spontaneous activity and polyphasic units in the infraspinatus and supraspinatus, and polyphasic units in flexor pollicis longus. Based on these findings and clinical presentation, a diagnosis of Parsonage-Turner syndrome was made. However, 2 months after the symptom onset, he had no pain, but had residual left shoulder abduction and improved external rotation weakness. | [
-0.1157163456082344,
-0.08445262163877487,
-0.03220425173640251,
-0.05691393464803696,
-0.08827139437198639,
-0.04766729474067688,
0.05607243627309799,
0.2277020364999771,
-0.07386678457260132,
0.02876262553036213,
0.14132514595985413,
0.07803522050380707,
0.05225415527820587,
0.2548019587... |
Preface
June 13-17, 2005
Preface
June 13-17, 2005in Colombo, Sri Lanka. With financial support from the International Development Research Centre (IDRC-Canada), the conference was organized by the Angelo King Institute for Economic and Business Studies of the De La Salle University in cooperation with the Laval University of Canada and the IPS-Sri Lanka. Profile of participants
The conference was the biggest meeting of the network with about 150 participants from 40 countries around the world including countries from South East Asia, South Asia, Africa, the Middle East and Latin America.
The participants reflected a wide variety of backgrounds in poverty research which augured well for sharing of knowledge and fruitful interactions among researchers and experts.
Host country
Only less than 6 months after it devastated by the tsunami triggered by the 2004 Sumatra-Andaman earthquake, Sri Lanka played a gracious host to the conference.
Prof. Wiswa Warnapala, Deputy Minister of Foreign Affairs said that the conference came at an opportune time given the recent tsunami that put millions into poverty where recovery may take many years to happen. On his part, Dr. Sarath Amunugama, Minister of Finance ix x of Sri Lanka, urged the conference participants to help his country in formulating appropriate policies that can jumpstart rehabilitation efforts.
Addressing the call of the two Sri Lankan national government officials, a session on the impact of the tsunami on poverty was conducted wherein two papers were presented and discussed with focus on the initial assessment and scenario analysis of the effect of the disaster and ways on how communities can recover.
Highlights of the proceedings
For the members of the CBMS subnetwork, it was another opportunity to learn about the experiences of other countries and researchers regarding the study of poverty. One of the topics during its subnetwork's meeting was on multidimensional poverty and policy assessment issues wherein two papers from Vietnam and one from the Philippines presented how CBMS can be used for this purpose. On the other hand, utilizing CBMS for poverty profile was the focus of the presentation from Bangladesh while the results of the pilot test were presented by Cambodia, Lao PDR and Pakistan. On the other hand, various methodologies used in the implementation of CBMS in their countries were discussed by country researchers from Indonesia, Thailand, Ghana, Burkina Faso, Benin and Senegal. Representative from Tanzania was also in attendance to present a proposal for CBMS implementation in their country.
Meanwhile, three papers from representatives of private and government organizations from Sri Lanka were also presented highlighting the important role of CBMS in the country.
Underscoring the increasing role of CBMS, a session on impact assessment and gender responsive budgeting was likewise included in the meeting.
A joint session of the CBMS and MPIA Networks was also held where the invited resource person, Mr. Guntur Sugiyarto of the Asian Development Bank, presented how CBMS data can be used in computable general equilibrium (CGE) modeling.
These various papers presented during the parallel sessions of the CBMS Network are all included in this volume. Aside from these, the papers presented by guest researchers during the plenary sessions on topics on the role of statistics in evidence-based policymaking, normative ways of integrating the different approaches to impact analysis among the MPIA, PMMA and CBMS networks, and the impacts of tsunami on poverty are also incorporated in this volume.
As part of the CBMS Network Meeting, a field visit to Sri Lankan CBMS sites was conducted and a documentation of this visit is included in this volume as well.
xi
| [
-0.005928399041295052,
-0.008837662637233734,
0.019789207726716995,
0.11401983350515366,
-0.0348062589764595,
-0.00036201905459165573,
-0.14138050377368927,
0.17748968303203583,
-0.006400701589882374,
0.04642147198319435,
-0.05094809830188751,
-0.061534252017736435,
0.1388033926486969,
0.0... |
Implementation research for today's HIV response: from theory to applied insights
Bohdan Nosyk
Eleanor Magongo Namusoke
Anne Trolard 0000-0002-4838-8134
Elvin H Geng elvin.geng@wustl.edu
Center for Dissemination and Implementation, Institute for Public Health, Division of Infectious Diseases, Department of Medicine, School of Medicine,
Washington University in St. Louis 63110, St. Louis, MO, USA.
Implementation research for today's HIV response: from theory to applied insights
67995F9CBD1D15145B0BB318E824FBEB10.1002/jia2.26305/full|10.1002/jia2.26305Received 16 May 2024; Accepted 24 May 2024
Global progress over the past 20 years has turned the tide on the HIV epidemic.Many countries are close to, and some have even reached, the UNAIDS 90-90-90 (and now 95-95-95) goals.Looking into the future, however, progress now requires not only continued attention, but a shift in scientific and strategic directions.Programmes must advance equitable reach to ensure that HIV prevention and treatment services meet the needs of populations and contexts that are outside of mainstream health services.We must shift from the continued rapid growth of capacity to sustainable systems embedded within policy and economic commitments around the world.Finally, the HIV response must evolve from a sole focus on HIV towards integrated services for comorbid conditions, both in persons living with HIV as well as to contribute to a global push for universal health coverage for all persons.
Implementation research is well-positioned to address this new generation of challenges and is, therefore, needed more than ever in the scientific response to HIV today.The growing prominence of implementation research for HIV is reflected in the assembly of this collection of articles for this supplement in the Journal of International AIDS Society (JIAS) on Implementation research and the HIV response: Taking stock and charting the way forward, as well as the growing number of funding opportunities, publication venues and professional settings which focus on implementation research.Implementation research has been defined as methods to promote the systematic uptake of research findings and other evidencebased practices into routine practice to improve the quality, reach and sustainability of health services [1].The scientific questions we seek to answer today are fundamentally questions about implementation: how to achieve greater and more equitable reach; how to sustain services in a changing economic and policy environment; how to integrate HIV services into wider public health structures.At the same time, the research needs of the HIV community also provide a critical testing ground to assess and refine implementation science methods to optimally deliver actionable insights for real-world problems and help us achieve greater epidemic control.Is the HIV research community up to the task?
This supplement responds strongly in the affirmative.This solicitation received over 100 submissions, with studies con-ducted in Africa, Asia, Europe, and North and South America.The 12 ultimately included cover a wide range of interventions-partner services, HIV self-testing, long-acting injectable antiretroviral therapy (ART) and stepped care for ART retention, and pre-exposure prophylaxis (PrEP)-as well as responses at the population level and for key populations, such as infants and young women.The articles also make use of a range of frameworks, from the Consolidated Framework for Implementation Research (CFIR) to Normalization Process Theory (NPT), as well as ways of classifying strategies (using the Expert Recommendations for Implementing Change) and adaptations (using the Framework for Reporting Adaptations and Modifications-Enhanced [FRAME]).Together, they offer concrete examples of how implementation science methods can be used to produce actionable research findings and, in some examples, meaningfully shift clinical practice at the population level.
Several of the studies focus on innovative strategies to extend the reach and efficiency of HIV testing-a critical step needed to close remaining gaps in the public health response.Even though the number of people living with an HIV diagnosis globally has risen rapidly over the last decade, as much as 30% in some settings still present with advanced disease at diagnosis, motivating renewed efforts to extend the reach of HIV testing.The observation that people who most need particular health services are often the last to receive them was coined the "inverse law" in 1971 [2].Several articles explore how to overcome this tendency, using both technological progress (e.g.self-testing kits) and novel ways to distribute testing outside of traditional brick-and-mortar health services.
Other studies use innovative methods to extend reach through leveraging social networks.Through a large clusterrandomized trial, Roy Paladhi et al. [3] demonstrated that distributing self-testing kits to partners of people newly diagnosed with HIV was equivalent to the standard of care in which in-person HIV testing is offered to contacts, and thus offering a route to greater efficiency in partner-assisted services.Such innovative approaches leveraging interpersonal networks (e.g.social networks) to deliver new testing technologies should also provoke considerations for screening for other chronic conditions (e.g.diabetes, hypertension).Sharma et al. [4] examined extending partner services to partners of partners, and showed programmatic approaches that leverage sexual networks to detect new cases are feasible and useful.
The potential for internet-based strategies in Asia for reach was highlighted by the paper from Nguyen et al. [5] who reported on the successful implementation of a webbased HIV self-testing programme through a population-based observational study of over 17,000 individuals in Vietnam.
The study provides a detailed examination at a subnational level of how to carry out a vast expansion of HIV testing, in this case, mediated by the internet, so that a testing programme need not contact testers in person, thus potentially reaching a segment of people who are reluctant to engage with standard health services.
Three papers in this supplement provide key information about the implementation and integration of novel HIV interventions into practice environments.Each is guided by implementation research frameworks that help connect findings with wider literature (including those outside of HIV).Vanhamel et al. [6] used extended Normalization Process Theory (NPT) to explain PrEP integration into HIV clinics in Belgium through interviews with clinic staff and observations.This study shows that wider adoption of a novel intervention is not simply replication at scale, but instead an adaptive process where individual clinics must be given sufficient leeway to innovate.Specifically, they found that both relational and normative restructuring (i.e.changes in the rules and relationships) are shaped by the existing potential and capacity at the facility.For example, they found that lower-volume clinics integrated PrEP services into existing workflows, whereas high-volume clinics created new procedures for PrEP services (such as grouping all PrEP patients on 1 day of the week).In a study focused on integrating long-acting injectable antiretroviral formulations into HIV care in the United States, Nguyen et al. [7] used CFIR to conduct a cross-sectional survey of 38 clinics.The study found clinics were most interested in technical assistance to address workflow development, payor challenges, staffing shortages for patient coordination and demand generation.The findings underscore the need for implementation, but through a process to find an approach that works within each setting.Chapuma et al. [8] used a narrative synthesis to identify failure points in early infant diagnosis and treatment (using deductive coding from CFIR), as well as Proctor's actor, action, action target framework [9] to develop concrete recommendations directed at policymakers, providers and patients.
Another important role of implementation research in the HIV response is to provide methods for developing implementation strategies so that actions taken to implement meet the desires of providers and patients, and, therefore, are more likely to be taken up.The notion of "preferences" is drawn from economic theory suggesting that humans make rational trade-offs under constraints (time, money) to decide on the goods and services they consume, and methods to illuminate these preferences are increasingly used in HIV research [10].Importantly, the idea of "preferences" is qualitatively different from acceptability because it places an individual's relationship to any good or service not as a relationship to that particular product, but rather in the context of their other potential choices (and costs).Mugambi et al. [11] use one such method, a discrete choice experiment, to assess the attributes that pregnant women want from HIV prevention services delivered in pharmacies.Interestingly, women found the range of services available (e.g.PrEP, testing and partner care) to be desirable, and were willing to give up other conveniences (such as location and cost) for more diversity in services.Pregnant women in Kenya chose choice, and that choice itself may create demand.
Velloza et al. [12] drew from human-centred design [13]another method that should be applied more frequently in implementation research in design of services-to adapt a peer counselling approach to PrEP delivery settings in South Africa.Design methods begin not with a cognitive technique, but an affective one-empathy.Empathic engagement between designers and end users enables truly collaborative co-creation of solutions.In this paper, the design was used to adapt a mental health service originally from Zimbabwe.The article by Tan et al. [14] takes a complementary approach.Instead of end-users as research partners, however, this paper positions "citizens" working in advocacy capacities as drivers of scientific standards.Chhun et al. [15] provide a report that applies such new standards-FRAME in this case [16,17]-to provider perceptions of improved implementation of a stepped care intervention for ART retention in youth, carefully tracking adaptations to clinical service approach in Kenya.
Simulation modelling for decision analysis and costeffectiveness offers great promise for implementation and to date has been underutilized in the field of implementation research addressing HIV [18].Enns et al. [19] demonstrated the utility of simulation modelling to project potential outcomes of a selection of evidence-based implementation interventions in HIV testing and PrEP.This study highlights the scalability of interventions as a key determinant of their impact at the city level, though modelling can otherwise be used in the pre-implementation stage to highlight and contrast key aspects of the potential reach, adaptation and maintenance of an intervention necessary to produce desired outcomes, especially over the longer term.This methodology is primed for further growth as a valuable addition to the implementation science toolbox.
Finally, to round out the issue, we have included a piece that takes stock of the global implementation research landscape.Lujintanon et al. [20] call attention to gaps in the applied implementation research literature, highlighting that strategies most often target patients or providers, and that approaches that act at a higher level on processes and systems-and mostly at the level of policymakers-often are lacking.This raises a question that has been posed in this Journal before as a challenge to the field of implementation science, where addressing structures and systems as well as policies must not be neglected simply because our most rigorous methods (e.g.trials) are more difficult to use at higher levels of the health system [21].
The public health response to HIV has adapted to decades of change and proven to be resilient, but once again must innovate to meet today's challenges.After the global financial crisis in 2007-2008, the global commitment to the HIV response defied expectations.While public health overall deteriorated during the global COVID-19 pandemic, HIV treatment programmes around the world managed to continue delivering lifesaving therapy.New challenges such as climate change, economic insecurity, and increasing criminalization in some regions, are coming to destabilize the HIV response.Our work is far from done.Embracing implementation research represents one potential way to meet the challenges of the day to advance a more nimble, person-centred and efficient response.The studies in this supplement demonstrate successful steps toward realization of the use of scientific tools from implementation science for solving realworld contemporary challenges in HIV treatment and prevention.The biomedical interventions developed in the field of HIV represent some of the most game-changing innovations in medicine this century [23,24].Can we use implementation science to create similar game-changing innovations in the way we prevent, diagnose, engage, and treat people living with and affected by HIV?We hope this supplement provides an answer by featuring the exciting, still-developing field of implementation science, and highlights its application to our continued efforts in tackling the global HIV epidemic.
A U T H O R S ' A F F I L I AT I O N S1 Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada; 2 Ministry of Health, Government of Uganda, Kampala, Uganda; 3C O M P E T I N G I N T E R E S T SThe authors declare no competing interests.A U T H O R S ' C O N T R I B U T I O N SEHG conceptualized and co-wrote the first draft; BN conceptualized and co-wrote the first draft; EMN made substantial contributions to the revision; AT make substantial contributions to the revised and final drafts.A C K N O W L E D G E M E N T SWe thank Makella Courdray, MD for supporting the editorial process.D ATA AVA I L A B I L I T Y S TAT E M E N TData sharing is not applicable to this article as no datasets were generated or analysed during the current study.
Welcome to implementation science. M P Eccles, B S Mittman, 10.1186/1748-5908-1-1Implement Sci. 1112006
The inverse care law. Tudor Hart, J , 10.1016/S0140-6736(71)92410-XS0140-6736(71)92410-XLancet. 29776961971
Effectiveness of HIV self-testing when offered within Assisted Partner Services in Western Kenya (APS-HIVST Study): a cluster randomized controlled trial. U R Paladhi, D A Katz, G Otieno, J P Hughes, H Lagat, S Masyuko, J Int AIDS Soc. 27S1e262982024
Providing HIV assisted partner services to partners of partners in western Kenya: an implementation science study. M Sharma, B W Mambo, H Kingston, G Otiento, S Masyuko, H Lagat, J Int AIDS Soc. 27S1e262802024
Investigating the effectiveness of web-based HIV self-test distribution and linkage to HIV treatment and PrEP among groups at elevated risk of HIV in Viet Nam provinces: a mixed methods analysis of implementation from pilot to scale-up. Vtt Nguyen, Y Dunkley, V H Son, A T Choko, Ptt Huong, P D Manh, J Int AIDS Soc. 27S1e262642024
Understanding adaptive responses in PrEP service delivery in Belgian HIV clinics: a multiple case study using an implementation science framework. J Vanhamel, T Reyniers, B Vuylsteke, S Callens, C Nostlinger, D H Veld, J Int AIDS Soc. 27S1e262602024
Long-acting injectable ART to advance health equity: a descriptive analysis of US clinic perspectives on barriers, needed support, and program goals for implementation from applications to the ALAI UP Project. N Nguyen, B Lane, S Golub, C Chastain, J Zucker, K King, J Int AIDS Soc. 27S1e262822024
Examining barriers to antiretroviral therapy initiation in infants living with HIV in sub-Saharan Africa despite the availability of point-of-care diagnostic testing: a narrative systematic review. C Chapuma, D Sakala, Nyang'wa, Mn, M C Hosseinipour, N Mbeye, M Matoga, J Int AIDS Soc. 27S1e262842024
Implementation strategies: recommendations for specifying and reporting. E K Proctor, B J Powell, J C Mcmillen, 10.1186/1748-5908-8-139Implement Sci. 811392013
Exploring relative preferences for HIV service features using discrete choice experiments: a synthetic review. I Eshun-Wilson, H Y Kim, S Schwartz, M Conte, D V Glidden, E H Geng, 10.1007/s11904-020-00520-3Curr HIV/AIDS Rep. 1752020
Women's preferences for HIV prevention service delivery in pharmacies during pregnancy in Western Kenya: a discrete choice experiment. L M Mugambi, B Ochieng, A Dollah, M Marwa, J Nyakina, J Kinuthia, J Int AIDS Soc. 27S1e263012024
Integrating a mental health intervention into PrEP services for South African young women: a human-centered implementation research approach to intervention development. J Velloza, N Ndimande-Khoza, L Mills, T Concepcion, S Gumede, H Chauke, J Int AIDS Soc. 27S1e262742024
The application of human-centered design approaches in health research and innovation: a narrative review of current practices. I Göttgens, S Oertelt-Prigione, 10.2196/28102JMIR MHealth UHealth. 912e281022021
Fostering citizenengaged HIV implementation science. Bxh Tan, S Y Chong, Dws Ho, Y X Wee, M H Jamal, Rkj Tan, J Int AIDS Soc. 27S1e262982024
Using FRAME to characterize provider-identified adaptations to a stepped care intervention for adolescents and youth living with HIV in Kenya: a mixed methods approach. N Chhun, D Oketch, K Agot, D I Mangale, J Badia, J Kibugi, J Int AIDS Soc. 27S1e262612024
The FRAME-IS: a framework for documenting modifications to implementation strategies in healthcare. C J Miller, M L Barnett, A A Baumann, C A Gutner, S Wiltsey-Stirman, 10.1186/s13012-021-01105-3Implement Sci. 161362021
The FRAME: an expanded framework for reporting adaptations and modifications to evidence-based interventions. S Wiltsey Stirman, A A Baumann, C J Miller, 10.1007/s11904-021-00550-5Curr HIV/AIDS Rep. 1412019. 2021Implement Sci
Estimating the potential value of MSM-focused evidence-based implementation interventions in three Ending the HIV Epidemic jurisdictions in the U.S.: a model-based analysis. B Enns, Y Sui, B C Guerra-Alejos, L Humphrey, M Piske, X Zang, J Int AIDS Soc. 27S1e262652024
Implementation strategies to improve HIV care cascade outcomes in low-and middle-income countries: a systematic review from 2014 to 2021. S Lujintanon, I Eshun-Wilson, Le Tourneau, N Beres, L Schwartz, S Baral, S , J Int AIDS Soc. 27S1e262632024
The question of the question: impactful implementation science to address the HIV epidemic. E H Geng, D Nash, N Phanuphak, K Green, S Solomon, A Grimsrud, 10.1016/S0140-6736(18)31434-XJ Int AIDS Soc. 2542022. May 9, 2024. May 9, 2024. 2018. 10144AAASLancet
| [
-0.1089492216706276,
0.06844030320644379,
-0.002141659613698721,
-0.0850331112742424,
-0.0004686061292886734,
0.0681421160697937,
-0.06945252418518066,
0.09135327488183975,
0.06372906267642975,
0.06720632314682007,
-0.006777917966246605,
0.07982732355594635,
-0.039411019533872604,
-0.02298... |
28 Mar 2006
PEDRO FORTUNY AYUSO
28 Mar 2006arXiv:cs/0603107v2 [cs.CR] TOWARDS AN INFORMATION-THEORETICALLY SAFE CRYPTOGRAPHIC PROTOCOL
We introduce what -if some kind of group action existsis a truly (information-theoretically) safe cryptographic communication system: a protocol which provides zero information to any passive adversary having full access to the channel.
enough to show that for any rational s ′ , there exist another rational number t ′ and matrices A ′ , B ′ such that the communication between Alice and Bob is the same (i.e. v 1 , v 2 and v 3 ). But this is trivial. Remark: The algorithm described above obviously does not work because GL 2 (Q) is non-commutative (in general, the linear group is noncommutative for dimension greater than 1).
What is needed?
A natural question comes to mind: what are the necessary conditions for a group action on a set for the above algorithm to provide a valid system? What we used above is:
(1) A set S (either finite or infinite) (the rational plane in the example).
(2) An action G×S 2 → S 2 of a commutative group G on S 2 (the group of movements of the plane in the example, which is not commutative). This condition means that after the above protocol is carried out completely, one always gets the original message.
(3) Conditions on the action. At least the following ones, but more might be needed:
• Given (s, t) ∈ S 2 and g ∈ G, for any s ′ ∈ S there are t ′ ∈ S and g ′ ∈ G such that g · (s, t) = g ′ · (s ′ , t ′ ). • For any (s, t)inS 2 and A, B ∈ G, there are (s ′ , t ′ ) and A ′ , B ′ ∈ G for which the sequences in the above algorithm are the same:
[(s, t)·A, (s, t) · A · B, (s, t) · A · B · A −1 ] = [(s ′ , t ′ ) · A ′ , (s ′ , t ′ ) · A ′ · B ′ , (s ′ , t ′ ) · A ′ · B ′ · (A ′ ) −1 ].
In fact, we do not need exactly an action of G on S 2 .
Definition 1. Let G be a (not necessarily commutative) group acting on a set T . We say that t ∈ T is comm-fixed if g · t = t for any g ∈ Comm(G) (the commutator of G). A subset S ⊂ T is comm-fixed if any s ∈ S is comm-fixed.
It is clear that a subset S ⊂ T is comm-fixed if and only if, for any s ∈ S and any g, h ∈ G, one has s = h −1 g −1 hgṡ. From this, it follows that we do not need exactly an action of a commutative group on S 2 but an action of a (not necessarily commutative) group on a set X ⊃ S 2 for which S 2 is comm-fixed and which satisfies, at least, condition (3) above.
We would like to prove two results; the first one seems relatively easy, while we have no clue (but are somewhat pessimistic) about the second one: Conjecture 1. With the above conditions on X, S 2 and G, the protocol described in section 1 is information-theoretically safe.
Question 1. Do there exist X, S and a group G acting on X for which S 2 ⊂ X is comm-fixed and such that the stated conditions hold?
Remark: it is obvious that S 2 can be changed by any set of the same cardinal.
E-mail address: pfortuny@sdf-eu.org
| [
-0.1959300935268402,
-0.0016167312860488892,
-0.12614530324935913,
-0.13952070474624634,
-0.02073502540588379,
0.055224183946847916,
0.1331615000963211,
-0.21845120191574097,
0.08771233260631561,
-0.012176224030554295,
0.0691680982708931,
0.06426271051168442,
0.13504092395305634,
-0.103522... |
arXiv:math.OC/0702212 8 Feb 2007
arXiv:math.OC/0702212 8 Feb 2007
| [
-0.3101308047771454,
-0.004973976872861385,
-0.1568450927734375,
0.08941780030727386,
-0.06919489800930023,
-0.22185984253883362,
0.014184762723743916,
0.030533043667674065,
0.001978673040866852,
-0.0731499046087265,
0.1918700635433197,
0.09917692840099335,
-0.0665862038731575,
0.007626948... |
Global conformal symmetry in scalar-tensor theories
15 Jul 2024
Eugeny Babichev
IJCLab
Université Paris-Saclay
CNRS/IN2P3
91405OrsayFrance
Christos Charmousis
IJCLab
Université Paris-Saclay
CNRS/IN2P3
91405OrsayFrance
Mokhtar Hassaine
Instituto de Matemática
Universidad de Talca
Casilla 747TalcaChile
Nicolas Lecoeur
IJCLab
Université Paris-Saclay
CNRS/IN2P3
91405OrsayFrance
Global conformal symmetry in scalar-tensor theories
15 Jul 2024519257DCEB84DDF24756724C5AA55F04arXiv:2407.11157v1[hep-th]
We study a subclass of Horndeski gravity which has both global conformal and shift symmetries.Global symmetries are characterised by the presence of a conserved current which has been shown to be of particular importance for the integrability features of the theory at hand yielding numerous compact object solutions.We find the general conserved current associated to global conformal symmetry of Horndeski theories.We discuss some of its properties, how it can be conveniently broken by physically relevant terms and, show how it is related to that of shift symmetry when shift symmetry is present.Given our results, we consider a particular theory and demonstrate how the presence of symmetries provides integrability for the given black hole solution.We then find the charged extension of the solution thanks to the conformal invariance of the Maxwell action.
Introduction
Symmetries of a physical system are defined as the transformations that do not change the mathematical structure of the system.From Noether's theorem, linking symmetries to conservation laws, to the elegant mathematical framework of group theory, symmetries offer powerful tools for simplifying complex systems and predicting physical behavior.A striking example in this regard concerns Maxwell's equations, which were originally discovered experimentally but could also have been derived from gauge symmetry.Indeed, one could even commence by defining the transformations and then finding the mathematical structure compatible with the transformations at hand.For example, the mathematical structure of relativity can be defined as the study of all structures compatible with the Lorentz symmetry.The determination of the symmetries of a system can also be a powerful instrument in order to generate nontrivial solutions from trivial ones or may play an important role for the integrability of the equations of motion.For all the above reasons amongst others, the identification of symmetries underlying a physical system is not an academic question it is rather a fundamental one.
One of such fundamental symmetries in physics is conformal symmetry which plays an important role in various theoretical setups as well as experimental observations.Indeed, conformal symmetry has attracted attention due to its rich mathematical structure and wide-ranging applications in condensed matter physics, high-energy physics, string theory, with a special mention on the AdS/CFT correspondence and holography.As mentioned before, symmetry can be helpful to obtain physically relevant solutions, and there is a simple example where conformal symmetry has played a crucial role in constructing the first counterexample to the no-hair conjecture.This concerns the case of a conformally coupled scalar field coupled to Einstein gravity in four dimensions [1,2].In this case, the traceless energy-momentum tensor yields a geometric restriction (vanishing Ricci scalar, R = 0), and this condition is of great utility for integrating the equations of motion, and also for establishing a uniqueness theorem [3].In the presence of a cosmological constant and of the self-interacting potential that does not break the conformal invariance of the scalar field action, the constraint R = 0 is modified to R = cst, and analytic black hole solutions with (A)dS asymptotics can also be found in this case [4,5].One can be less restrictive and demand that conformal invariance be effective only for the scalar field equation and not necessarily for the scalar field action.It is from this point of view that Fernandes has shown recently that the standard conformal action of a scalar field in four dimensions can be modified by incorporating a scalar Gauss-Bonnet sector, and the resulting geometric constraint is now given by a constant linear combination of the Ricci scalar with the Gauss-Bonnet [6].Note that the most general scalar field action in four dimensions yielding a second-order and conformally invariant equation has been identified in Ref. [7].We also have an interesting example where, starting from a quite general class of the Horndeski theory in d = 4, and requiring the integrability of the equations, the resulting action was a mix of Lagrangians that had conformal invariance in four and five dimensions [8].In other words although the symmetry may not be present in a given dimension the actions at hand still maintain some of their integrability properties which makes them interesting beyond their field of direct application.
In the present work, we will dwell on this direction and consider scalar tensor theories admitting global symmetries.A widely encountered case in the literature is that of shift symmetry for the scalar field.This symmetry for the action has been proven to be incredibly useful for finding new solutions.The simple reason is that the scalar field equation can, for this subclass of symmetric theories, be written as a divergence of the Noether current related to the symmetry, and thus it can be directly integrated to give the first integral in special cases, such as, in particular, for spherically symmetric static cases.This has given numerous black hole metrics starting from stealth static solutions [9] as well as stationary metrics [10,11] to more recently black holes with primary hair [12] (for a very recent review of exact solutions see [13,14]).Once black hole solutions are known one can also find physically relevant neutron star solutions [15] and construct exotic wormhole geometries in closed form [16].It is then natural to seek theories employing a different symmetry that provides a corresponding conservation of a Noether current.The symmetry we will consider is -global conformal symmetry1 -and we will show how to use these two symmetries in order to find spherically symmetric black hole solutions.
In the next section we will discuss the relevant theories, sub-classes of Horndeski, with global conformal symmetry and then find the conserved current associated to the symmetry at hand.We will then discuss a particular example and how the symmetry is manifest in its integrability adding a Maxwell field (which is conformally invariant) for the latter part.We will also discuss the possible extensions and limitations of our findings.
Scalar-tensor theories with global conformal symmetry
The presence of a global conformal symmetry in the theory implies the existence of a Noether current which is accompanied by an equation for its conservation.In this section we intro-duce the sub-class of Horndeski theories possessing global conformal symmetry and find the Noether current corresponding to the symmetry at hand.We then also consider the presence of a term breaking the conformal symmetry in order to attend to more physically relevant theories and their solutions.
Action of Horndeski theory with global conformal symmetry
In four dimensions, the most general scalar-tensor theory with second order field equations is given by the Horndeski action [18][19][20],
S [g µν , φ] = d 4 x √ −g G 2 − G 3 φ + G 4 R + G 4X ( φ) 2 − φ µν φ µν +G 5 G µν φ µν − G 5X 6 ( φ) 3 − 3 φφ µν φ µν + 2φ µν φ νρ φ µ ρ ,(1)
where G i ≡ G i (X, φ) are arbitrary functions of the scalar field φ and the kinetic term
X = − 1 2 (∇ µ φ∇ µ φ).
Within the Horndeski action there is a class of theories that admits global conformal invariance:
g µν → ω 2 g µν , φ → φ ω ,(2)
where ω is a constant scaling parameter.Indeed, the most general subclass of Horndeski theory possessing global conformal invariance with a nontrivial scalar and metric transformation (2) was given in Ref. [21].In this class, the functions G i (X, φ) have a specific dependence on φ and X:
G 2 = φ 4 a 2 (Y ), G 3 = φa 3 (Y ), G 4 = φ 2 a 4 (Y ), G 5 = a 4 (Y ) φ ,(3)
where a i are arbitrary functions of Y and Y is defined as a combination of X and φ: Y = X/φ 4 .For further reference, we explicitly write the Horndeski action with global conformal symmetry:
S C [g µν , φ] = d 4 x √ −g φ 4 a 2 (Y ) − φa 3 (Y ) φ + φ 2 a 4 (Y )R + a 4Y φ 2 ( φ) 2 − φ µν φ µν + a 5 (Y ) φ G µν φ µν − a 5Y 6φ 5 ( φ) 3 − 3 φφ µν φ µν + 2φ µν φ νρ φ µ ρ ,(4)
where the subscript 'C' refers to the global conformal symmetry of the action.One can check that the action ( 4) is invariant under transformation (2).
Our focus in this paper will be the study of (4) however it is interesting to note that there are two more cases of global (conformal) symmetry that we can add to the generic one above.
The first is still a global conformal transformation with a trivial transformation for the scalar field, namely
g µν → ω 2 g µν , φ → φ,(5)
where the invariant action, in this case, is given by
S C0 = d 4 x √ −g (a 2 (φ)X 2 − a 3 (φ)X φ + a 5 (φ)G µν φ µ φ ν + a 6 (φ) G) . (6)
where G stands for the Gauss-Bonnet density.Note that the last term in ( 6) is a part of the Horndeski action (1), see Ref. [20].It is interesting to note that for the particular values, a 2 = 2α, a 3 = −4α, a 5 = 4α and a 6 = −αφ, one recovers the action of Fernandes with linear Gauss-Bonnet coupling whose equation of motion has conformal symmetry while the action itself does not [6].
We can also consider a trivial transformation of the metric instead, namely
g µν → g µν , φ → φ ω .(7)
Introducing Z = X/φ 2 , one can write the following invariant isometric action in this case
S C [g µν , φ] = d 4 x √ −g a 2 (Z) − 1 φ a 3 (Z) φ + a 4 (Z)R + a 4Z φ 2 ( φ) 2 − φ µν φ µν + a 5 (Z) φ G µν φ µν − a 5Z 6φ 3 ( φ) 3 − 3 φφ µν φ µν + 2φ µν φ νρ φ µ ρ .(8)
Noether current
Given the action (4) with the symmetry (2), we need to figure out the Noether current corresponding to this symmetry.To do this we write the action in a general form,
S C = d 4 x L(g, ∂g, ∂∂g, φ, ∂φ, ∂∂φ),(9)
where partial derivatives mean symbolically the partial derivative w.r.t.coordinates, e.g.∂∂g imply ∂ µ ∂ ν g αβ etc.The Euler-Lagrange equations read then,
0 = δS C δg µν = ∂L ∂g µν − ∂ ρ ∂L ∂ (∂ ρ g µν ) + ∂ ρ ∂ σ ∂L ∂ (∂ ρ ∂ σ g µν ) , 0 = δS C δφ = ∂L ∂φ − ∂ ρ ∂L ∂ (∂ ρ φ) + ∂ ρ ∂ σ ∂L ∂ (∂ ρ ∂ σ φ) .(10)
Let us collectively denote the metric and the scalar field as ϕ a for simplicity.By assumption, the action ( 9) is invariant under the transformation (in our case the global conformal transformation) ϕ a → ϕ a + ∆ϕ a .This implies that δL under this transformation is vanishing or equal to a total divergence δL = ∂ ρ j ρ (in the case where j ρ = 0, one refers to a quasi invariance, rather than to invariance).Using equations of motion (10), one can write the change of L as follows:
δL = ∂ ρ ∂L ∂ (∂ ρ ϕ a ) ∆ϕ a + ∂ ρ ∂L ∂ (∂ ρ ∂ σ ϕ a ) ∂ σ ∆ϕ a − ∆ϕ a ∂ σ ∂L ∂ (∂ ρ ∂ σ ϕ a ) ,(11)
which implies that the conserved current J ρ C , such that ∂ ρ J ρ C = 0, is given by,
J ρ C = ∂L ∂ (∂ ρ ϕ a ) − ∂ σ ∂L ∂ (∂ ρ ∂ σ ϕ a ) ∆ϕ a + ∂L ∂ (∂ ρ ∂ σ ϕ a ) ∂ σ ∆ϕ a − j ρ .(12)
To be perfectly clear, the summation convention is used not only for the spacetime indices ρ, σ, etc., but also for the field indices a.For global conformal symmetry (2) it is convenient to present its transformation in the infinitesimal form ω = 1 − ǫ, so that ∆g µν = 2ǫg µν and ∆φ = ǫφ for the field transformations.In our case, the Lagrangian density L itself, not just the action, is invariant under such a transformation, i. e. j ρ = 0. Finally, a direct computation gives the following form2 of J ρ C :
J ρ C = ǫ √ −gJ ρ C ,(13)
where J ρ C is a covariantly conserved Lorentz vector,
∇ ρ J ρ C = 0. (14)
The Noether current J ρ C can be presented as a sum of four terms (which corresponds to four free a i functions),
J ρ C = 5 i=2 J ρ C,i ,(15)
where the J ρ C,i are given in Appendix A.
Let us also make the assumption, that apart from global conformal invariance, the action is also shift symmetric, i. e. the action is invariant under the change φ → φ + cst.The scope of this is to have two conserved currents at the same time, which may imply (or not) an extra first integral of the equations of motion.We will see later, however, that this subclass of theories has its limitations.
In case of presence of both global conformal and shift symmetries, the conformal current J ρ C,i has a non-trivial relation to the Noether current of shift symmetry J ρ
J ρ C = φJ ρ + B ρ ,(16)
where J ρ reads,
J ρ = 1 √ −g δS δ∂ ρ φ ,(17)
and note that B ρ does not depend on φ explicitly.
The above relation ( 16) can be extended to the case of a theory possessing global conformal symmetry, but no shift symmetry.In this case one can still define the quantity J ρ , although it is not a conserved quantity 3 .The explicit expressions for J ρ and B ρ are given in Appendix A.
Breaking symmetry by Einstein-Hilbert term
As we discussed in the previous section, the conservation of the conformal current J ρ C is given by Eq. ( 14).This equation, however, can be also seen as a consequence of the equations of motion.Indeed, denoting again the fields collectively as ϕ a for brevity, the transformation of L under ϕ a → ϕ a + ∆ϕ a reads
δL = ∂L ∂ϕ a ∆ϕ a + ∂L ∂ (∂ ρ ϕ a ) ∂ ρ ∆ϕ a + ∂L ∂ (∂ ρ ∂ σ ϕ a ) ∂ ρ ∂ σ ∆ϕ a .(18)
Combining now the Euler-Lagrange equations (10), and the definition (12) of J ρ C (where we recall that j ρ = 0), one obtains,
∂ ρ J ρ C = − δS C δϕ a ∆ϕ a + δL. (19)
Using the fact that δL = 0 under the infinitesimal global conformal transformation ∆g µν = 2ǫg µν and ∆φ = ǫφ, together with the relation (13) between J ρ C and J ρ C , one finally gets
∇ ρ J ρ C = −g µν E C µν − φE C φ ,(20)
where for short, we have introduced the following notations,
E C µν ≡ 2 √ −g δS C δg µν , E C φ ≡ 1 √ −g δS C δφ .(21)
In a word, the conservation on shell of the global conformal Noether current J ρ C can be immediately understood from Eq. ( 20).
Let us now consider adding a symmetry breaking term to a theory with global conformal symmetry.This may be important, for example, if we want to have an Einstein-Hilbert term in the action, so that we can restore General relativity in some limit.Clearly, the action with a minimally coupled Einstein-Hilbert term is not invariant under global conformal transformations.This in turn implies that the current J µ C is no longer conserved.Let us see how Eq. ( 14) is modified when we add a general symmetry breaking term in the action, i.e. we consider the action S = S C + S b , where S C is an invariant action under (2) and S b breaks the global conformal invariance.One gets that, on shell,
∇ µ J µ C = g µν E b µν + φE b φ ,(22)
where we used the equations of motion E C µν + E b µν = 0, E C µν + E b µν = 0 together with Eq. (20).
Take for instance S b to be the pure Einstein-Hilbert action, with Lagrangian
L b = √ −gζR,
where the constant ζ is normally identified with Planck mass squared.In this case, E b µν = 2ζG µν while E b φ = 0, and hence (22) becomes simply,
∇ µ J µ C = −2ζR.(23)
The conformal current is thus not conserved, and is rather sourced by the symmetry breaking term, the Ricci scalar.
Asymptotically flat black hole solutions and its extension
We are now ready to apply our findings for particular examples of black hole solutions in theories with (partially broken) global conformal symmetry.We will focus our attention on the manifestation of the symmetry within the solutions, and discuss possible implications of the symmetry for finding new solutions.Our first example is a class of asymptotically flat black hole solutions in Horndeski theory, presented in Ref. [22].In this reference, it has been noticed that a class of Horndeski theories giving rise to exact black hole solutions has (partial) global conformal invariance, but no consequence of the presence of the symmetry and the properties of the solution were discussed.
Here we take another look at this black hole solutions from the perspective of the discussion above, i.e. the presence the conformal current and its (partial) conservation.The lesson drawn from this example will allow us to further generalise the solution of Ref. [22] to include the Maxwell gauge field which is (locally) conformally invariant.
Asymptotically flat solutions in Horndeski theory from the perspective of symmetries of the theory
A class of asymptotically flat black hole solutions presented in Ref. [22] was found in a subclass of Horndeski theory,
S 1 = d 4 x √ −g ζ + β (∂φ) 2 /2 R − η 2 (∂φ) 2 − β 2(∂φ) 2 ( φ) 2 − (∇ µ ∇ ν φ) 2 . (24)
where ζ = M 2 Pl /(16π) and η and β are dimensionless constants (note that the scalar field has dimension of mass).In terms of the general action (1), the theory ( 24) is given as
G 2 = ηX, G 4 = ζ + β √ −X, and G 3 = G 5 = 0.
The theory is shift-symmetric, i.e. the action is invariant under the change φ → φ + cst.Note also that for ζ = 0, the theory also enjoys global conformal invariance (2).The pure Einstein-Hilbert term ζR in the action breaks this symmetry.It is, however, necessary to include the Einstein-Hilbert term, since without it the theory with G 4 = β √ −X does not propagate the spin-2 graviton degrees of freedom, which renders the theory physically uninteresting (see for example [20]).Moreover, the solution of [22] does not have a well-defined limit as ζ → 0.
Let us analyse possible solutions of the theory having in mind symmetries of the action (24).The exact shift symmetry implies conservation of the shift current,
∇ µ J µ = 0. (25)
The partially broken global conformal symmetry, on the other hand, yields a non-conservation of the conformal current J µ C , as given in (23).Assuming a static spherically symmetric ansatz,
ds 2 = −h(r)dt 2 + dr 2 f (r) + r 2 dθ 2 + sin 2 θdϕ 2 , φ = φ(r),(26)
one obtains the following general solution for φ ′ by integrating (25):
φ ′ = ± β ηr 2 2 f − C ηr 2 1 √ f h , (27)
where C is a constant of integration, standing for scalar charge (associated with shift symmetry).
In [22], it has been assumed that the scalar charge is zero, based on the assumption that the norm of the shift-symmetry current J 2 = (J µ J µ ) should be finite everywhere, including the horizon of a black hole.It has been noted in [23] that, however, the norm J 2 diverges at the horizon of a black hole in a theory with linear scalar-Gauss-Bonnet coupling φG for a solution that seems physically reasonable.Therefore one may think of relaxing the condition of finiteness of the norm J 2 and to consider arbitrary C in (27).Nevertheless, one arrives to the same conclusion, C = 0, asking a more physically motivated requirement of finiteness of X (see a discussion on this subject in [24]).Hence, the condition C = 0 is in fact equivalent to J µ = 0.
Having established that J µ = 0, we now move on to analyse the conformal current equation (23).Using (41)-(43) it is easy to see that for the theory (24) we have
J ρ C = φ J ρ .(28)
Substituting the above relation into (23) and taking into account that J µ = 0 we immediately get R = 0.
In Ref. [22] this condition of vanishing Ricci scalar was identified by combining equations of motion, without referring to the (partial) global conformal symmetry.The use of the global conformal symmetry by the application of the global current conservation (23) leads immediately to the conclusion that the spacetime has vanishing Ricci scalar.
After finding (27) with C = 0 and (29), it is then a matter of simple calculations to use other equations of motion to find the metric,
f (r) = h(r) = 1 − µ r − β 2 2ζηr 2 , (30)
where µ is another integration constant.Note that the presence of the term proportional to 1/r 2 is a consequence of global conformal invariance (see below with the introduction of the conformally invariant Maxwell term (37).Substituting the above expression in (27), one can explicitly calculate φ = φ(r).The corresponding expression can be found in Ref. [22].
Before closing this section, it is instructive to consider briefly one more possibility which is allowed for our action due to global shift symmetry of the scalar; namely a linear time dependence for the scalar field, φ = qt + ψ(r), see [9,25,26].Then one can show that the scalar charge C is always forced to be zero from the presence of the (tr) equation of motion [27].In a certain sense the integration constant q takes over the presence of the scalar charge C. Therefore this imposes that J r = 0. However note that J t = 0 and this gives for our conformal current,
J t C = qt J t (31)
which in turn (due to the explicit presence of t) requires that the Ricci scalar is no longer zero, R = 0 according to (23).The corresponding solution was found in [22] to be non asymptotically flat.We see here that time dependence in φ sources in turn the Einstein Hilbert term present in the action precisely due to the presence of the additional conformal symmetry.We therefore set q = 0 for the forthcoming section.
Extension to include the Maxwell field
Now, having in mind the example of black hole solutions we considered above, where the role of (partial) conformal symmetry was identified, one may think of possible extensions of this solution.Indeed, since our focus in the paper is the conformal symmetry, it is natural to include the Maxwell electromagnetic field A µ in the discussion.The action for standard electromagnetic field has local conformal invariance, hence also global invariance.
To be precise, we consider a scalar-tensor-vector theory, with the (partial) global conformal invariance whose action on the dynamical fields reads
g µν → ω 2 g µν , φ → φ ω , A µ → A µ .(32)
Clearly, under the transformation (32) the Maxwell action,
S EM = d 4 x √ −g − 1 4 F µν F µν ,(33)
where
F µν = ∂ µ A ν − ∂ ν A µ , is invariant.
We may guess therefore that the combination of the two actions,
S Ext = S 1 + S EM ,(34)
also has a solution, similar to the one found in Ref. [22].
Following the logic of the previous discussion in Sec.3.1, we find that the theory (34) has shift symmetry φ → φ + cst, partial global conformal symmetry and, in addition, the gauge symmetry of the vector field.It is not difficult to see that the Maxwell term does not contribute to both currents -associated to shift and conformal symmetry, -therefore those currents for the theory (34) are the same as for the original theory (24).
This implies that the expression for the scalar field in terms of metric (27) remains the same, with C = 0 for the reasons explained in 3.1.Similarly, the conclusion that the Ricci scalar is zero ( 29) is not altered by the presence of the the Maxwell term.On the other hand, the variation of the action (34) with respect to A µ gives Maxwell's equations,
∇ µ F µν = 0. (35)
As we assumed spherical symmetry and staticity, one can look to a purely electric ansatz A µ = {A 0 (r), 0, 0, 0}.It is easy to integrate (35) as
A ′ 0 (r) = − h f Q r 2 ,(36)
where Q is a constant of integration that has a meaning of an electric charge of a black hole.
For the moment, we have obtained both φ and A µ in terms of the metric function, and in addition we have a constraint R = 0. Taking into account the form of the metric in the case considered above, Eq. (30), and the Reissner-Nordström solution in general relativity, one can guess the solution for f and h in the theory (34)
f (r) = h(r) = 1 − µ r + Q 2 4ζr 2 − β 2 2ζηr 2 .(37)
In the above expression we combined linearly the 'usual' term from the backreaction of the Maxwell field and the gravity modification term, since they both come with the same power of r.Direct substitution of the Eq. ( 27) with C = 0, Eqs. ( 36) and (37) in the metric equations verifies that this is indeed a black hole solution.
To sum up, an electrically charged black hole solution to the theory with the action (34) is given by the metric (37) and the scalar and gauge fields,
φ ′ = ± β ηr 2 2 f , A µ dx µ = Q r dt,(38)
where f is given in (37).The dyonic extension of this purely electric solution is straightforward, and given by
f (r) = h(r) = 1 − µ r + Q 2 + Q 2 m 4ζr 2 − β 2 2ζηr 2 , φ ′ = ± β ηr 2 2 f , A µ dx µ = Q r dt + Q m cos θdϕ,(39)
where Q m stands for the magnetic charge.
Discussion
In this paper we have studied the consequences of global symmetries to scalar tensor theories and how they affect the integrability of the equations of motion.We examined global conformal symmetry and we have given the relevant conserved current and the equations of motion.The conformal current has a neat relation to the shift symmetric current, when the latter is also present.
It is well known that shift symmetric Horndeski theories admit a plethora of black hole solutions (see for example the recent reviews [13,14]) as well as solutions with primary scalar hair [12,28,29]).Here we considered a theory with partially broken global conformal symmetry as well as shift symmetry and studied in detail what the symmetries imply on the solution itself.We found the electrically charged (and dyonic) extension of the black hole solution presented in Ref. [22].We also noted how the combined presence of both symmetries can drastically restrict possible solutions in the presence of a linear time dependent scalar.Thus the presence of combined symmetries can be both beneficial or disadvantageous for finding new solutions, depending on a specific set up.
For future work, it would be interesting to study the extension of our example construction to higher dimensions.In this case, one could consider breaking global conformal invariance via higher order Lovelock terms in a similar fashion as was considered for local conformal invariance recently [6].Another interesting possibility would be to extend our study to four dimensional beyond Horndeski theories with exact (unbroken) global conformal and shift invariance, since the requirement of both exact symmetries in Horndeski action leads to non-dynamical spin-2 perturbations.
But without doubt the most interesting question would be to study theories with (broken or unbroken) global conformal invariance which are not shift symmetric and thus have an explicit φ dependence.The additional difficulty in this case resides with the fact that the current depends not only on the (first or second) derivatives of the scalar but also on the scalar itself.This makes the first step towards solving the equations of motion technically harder.For example, in the case of shift symmetry, one obtains an algebraic condition on the first derivative of the scalar with respect to the metric (see for example [9]).The presence of symmetry and the conserved current may nevertheless be important in making progress towards obtaining black hole vacua in such non shift symmetric theories.
The combination of local conformal symmetry and global shift symmetry has been studied, but for bi-scalar theories, giving black holes with primary hair in certain cases[17]
This comes from the fact that L is a scalar density of weight 1 and therefore J ρ C is a vector density of weight 1.
Note that in the absence of shift symmetry there is an ambiguity in defining J ρ , i.e. for equivalent actions that differ by a total derivative, J ρ given by(17) do not coincide in general. Working with a fixed form of the action removes this uncertainty.
AcknowledgmentsWe thank Adolfo Cisterna for interesting discussions.E.B. and C.C. acknowledge the support of ANR grant StronG (ANR-22-CE31-0015-01).The work of M.H. is partially supported by FONDECYT grant 1210889.A Noether current for Horndeski theories with global conformal symmetryHere we give expressions for each contribution of G i to the Noether current of for Horndeski theories with global conformal symmetry:where we used the notation X µ = ∂ µ X.Note that here G i are not arbitrary, but are constrained to have the form (3) in order for the action to be invariant under transformations(2).The above expressions for J ρ C,i can be written in more compact form:whereandThe expressions (42), valid even for non-shift symmetric theories, coincide with those introduced in Ref.[20].When shift symmetry is absent, J ρ is not a conserved current.If a theory enjoys shift symmetry, i.e. when all the functions G i do not depend explicitly on φ, then J ρ = 1 √ −g δS δ∂ρφ is a conserved Noether current, ∇ µ J µ = 0.The latter conservation law coincides with the equation of motion of the scalar field.
. N M Bocharova, K Bronnikov, V N Melnikov Vestn, Mosk. Univ. Ser.III Fiz. Astron. 67061970
Exact solutions of einstein-conformal scalar equations. J D Bekenstein, 10.1016/0003-4916(74)90124-9Annals of Physics. 8221974
The gravity of three-forms. B C Xanthopoulos, T Zannias, J. Math. Phys. 3271991
De Sitter black hole with a conformally coupled scalar field in four-dimensions. C Martinez, R Troncoso, J Zanelli, 10.1103/PhysRevD.67.024008arXiv:hep-th/0205319Phys. Rev. D. 67240082003
Topological black holes dressed with a conformally coupled scalar field and electric charge. C Martinez, J P Staforelli, R Troncoso, 10.1103/PhysRevD.74.044028arXiv:hep-th/0512022Phys. Rev. D. 74440282006
Gravity with a generalized conformal scalar field: theory and solutions. P G S Fernandes, 10.1103/PhysRevD.103.104065arXiv:2105.04687Phys. Rev. D. 103101040652021gr-qc
Non-Noetherian conformal scalar fields. E Ayón-Beato, M Hassaine, 10.1016/j.aop.2023.169567arXiv:2305.09806Annals Phys. 4601695672024hep-th
Selecting Horndeski theories without apparent symmetries and their black hole solutions. E Babichev, C Charmousis, M Hassaine, N Lecoeur, 10.1103/PhysRevD.108.024019arXiv:2303.04126Phys. Rev. D. 1082240192023gr-qc
Dressing a black hole with a time-dependent Galileon. E Babichev, C Charmousis, 10.1007/JHEP08(2014)106arXiv:1312.3204JHEP. 081062014gr-qc
Rotating Black Holes in Higher Order Gravity. C Charmousis, M Crisostomi, R Gregory, N Stergioulas, 10.1103/PhysRevD.100.084020arXiv:1903.05519Phys. Rev. D. 1008840202019hep-th
Disforming the Kerr metric. T Anson, E Babichev, C Charmousis, M Hassaine, 10.1007/JHEP01(2021)018arXiv:2006.06461JHEP. 01182021gr-qc
Black holes with primary scalar hair. A Bakopoulos, C Charmousis, P Kanti, N Lecoeur, T Nakas, 10.1103/PhysRevD.109.024032arXiv:2310.11919Phys. Rev. D. 1092240322024gr-qc
Exact black hole solutions in higher-order scalar-tensor theories. E Babichev, C Charmousis, N Lecoeur, arXiv:2309.12229gr-qc
Exact black hole solutions in scalar-tensor theories. N Lecoeur, arXiv:2406.11095Laboratoire de Physique des 2 Infinis Irène Joliot-Curie. 2024PhD thesisgr-qc
Astrophysical constraints on compact objects in 4D Einstein-Gauss-Bonnet gravity. C Charmousis, A Lehébel, E Smyrniotis, N Stergioulas, 10.1088/1475-7516/2022/02/033arXiv:2109.01149JCAP. 0202332022gr-qc
Traversable wormholes in beyond Horndeski theories. A Bakopoulos, C Charmousis, P Kanti, 10.1088/1475-7516/2022/05/022arXiv:2111.09857JCAP. 05222022gr-qc
Black Holes in Bi-scalar Extensions of Horndeski Theories. C Charmousis, T Kolyvaris, E Papantonopoulos, M Tsoukalas, 10.1007/JHEP07(2014)085arXiv:1404.1024JHEP. 07852014gr-qc
Second-order scalar-tensor field equations in a four-dimensional space. G W Horndeski, 10.1007/BF01807638Int. J. Theor. Phys. 101974
From k-essence to generalised Galileons. C Deffayet, X Gao, D A Steer, G Zahariade, 10.1103/PhysRevD.84.064039arXiv:1103.3260Phys. Rev. D. 84640392011hep-th
Generalized G-inflation: Inflation with the most general second-order field equations. T Kobayashi, M Yamaguchi, J Yokoyama, 10.1143/PTP.126.511arXiv:1105.5723Prog. Theor. Phys. 1262011hep-th
Generalised Scale Invariant Theories. A Padilla, D Stefanyszyn, M Tsoukalas, 10.1103/PhysRevD.89.065009arXiv:1312.0975Phys. Rev. D. 896650092014hep-th
Asymptotically flat black holes in Horndeski theory and beyond. E Babichev, C Charmousis, A Lehébel, 10.1088/1475-7516/2017/04/027arXiv:1702.01938JCAP. 04272017gr-qc
Black holes and stars in Horndeski theory. E Babichev, C Charmousis, A Lehébel, 10.1088/0264-9381/33/15/154002arXiv:1604.06402Class. Quant. Grav. 33151540022016gr-qc
The cosmic trimmer: Black-hole hair in scalar-Gauss-Bonnet gravity is altered by cosmology. E Babichev, I Sawicki, L G Trombetta, arXiv:2403.15537gr-qc
Galileon accretion. E Babichev, 10.1103/PhysRevD.83.024008arXiv:1009.2921Phys. Rev. D. 83240082011hep-th
Escaping from the black hole?. E Babichev, V F Mukhanov, A Vikman, 10.1088/1126-6708/2006/09/061arXiv:hep-th/0604075JHEP. 09612006
Charged Galileon black holes. E Babichev, C Charmousis, M Hassaine, 10.1088/1475-7516/2015/05/031arXiv:1503.02545JCAP. 05312015gr-qc
Endowing black holes with beyond-Horndeski primary hair: An exact solution framework for scalarizing in every dimension. O Baake, A Cisterna, M Hassaine, U Hernandez-Vera, 10.1103/PhysRevD.109.064024arXiv:2312.05207Phys. Rev. D. 1096640242024hep-th
Compact objects with primary hair in shift and parity symmetric beyond Horndeski gravities. A Bakopoulos, N Chatzifotis, T Nakas, arXiv:2312.17198gr-qc
| [
-0.20516234636306763,
-0.1796647012233734,
0.04138941317796707,
-0.015223199501633644,
0.1282484084367752,
-0.04866047203540802,
-0.05723162740468979,
-0.03333183005452156,
0.06213262304663658,
-0.024901647120714188,
0.05337675288319588,
-0.0928013026714325,
-0.1748373806476593,
0.07099893... |
Arguments for the Effectiveness of Human Problem Solving
June 12, 2018
Frantisek Duris
Faculty of Mathematics, Physics and Informatics
Comenius University
BratislavaSlovakia
Arguments for the Effectiveness of Human Problem Solving
June 12, 20182D546B7F797074E863821509C7EB186BarXiv:1506.02930v2[cs.AI]Human problem solvingeffectivenessmechanismheuristiccognitive architecture
The question of how humans solve problem has been addressed extensively.However, the direct study of the effectiveness of this process seems to be overlooked.In this paper, we address the issue of the effectiveness of human problem solving: we analyze where this effectiveness comes from and what cognitive mechanisms or heuristics are involved.Our results are based on the optimal probabilistic problem solving strategy that appeared in Solomonoff paper on general problem solving system.We provide arguments that a certain set of cognitive mechanisms or heuristics drive human problem solving in the similar manner as the optimal Solomonoff strategy.The results presented in this paper can serve both cognitive psychology in better understanding of human problem solving processes as well as artificial intelligence in designing more human-like agents.
Introduction
Problem solving is probably the most common activity of all organisms, especially of humans.We deal with various problems throughout our lives, from infancy to adulthood.Therefore, it is not surprising that an extensive effort has been made to understand the cognitive processes responsible for this ability, and many models of human problem solving have been presented (Davidson, 1995(Davidson, , 2003;;Davidson & Sternberg, 1986;Hummel & Holyoak, 1997;Ohlsson, 1992;Polya, 1957;Weisberg, 1992;Woods, 2000).Additional models of problem solving and, generally, of human cognitive skills have been proposed by research groups on cognitive architectures like ICARUS (Langley & Choi, 2006;Langley, Laird, & Rogers, 2009;Langley & Rogers, 2005;Langley & Trivedi, 2013), ACT-R (J.Anderson, 1996;J. Anderson et al., 2004), SOAR (Laird, 2008;Langley et al., 2009;Nason & Laird, 2005), Polyscheme (Cassimatis, 2006;Kurup, Bignoli, Scally, & Cassimatis, 2011), and others (see Duch, Oentaryo, & Pasquire, 2008;Langley et al., 2009).However, while the current state of research can explain some questions about the scope of problems the human brain can solve, we lack some form of explanations what makes solving (novel) problems so fast, i.e., effective.We note that there have been proposed models or algorithms for general problem solving with special focus on the provable Email: fduris@dcs.fmph.uniba.skeffectiveness (Fink, 2004;Hutter, 2002Hutter, , 2005;;Schmidhuber, 2004;Solomonoff, 1986), but these models are not designed to mimic human problem solving process, and as such offer little explanation of this feat.Thus, the question why humans are still more effective problems solvers than computers is still left open (Poole & Mackworth, 2010).
In this paper, we present some ideas on this problem.The core of our arguments revolves around an optimal betting strategy for the following scenario.You are in the gambling house making bets.All bets win the same prize but they have different probability p i of winning and come at different cost d i .If you can make each bet only once, what strategy will give you the greatest win probability per dollar?According to Solomonoff (1986), the best strategy is to sort the bets by the ratio p i /d i and take them one by one starting from the top.We argue how this strategy relates to the human problem solving process, and what does it mean for its effectiveness.
The paper is organized as follows.First, we outline what is an optimal problem solving strategy in the sense of Solomonoff betting strategy.In the subsequent six sections, we argue how particular six cognitive mechanisms play role in driving human problem solving by the same manner.Finally, we close the paper with some remarks on the applicability of those six cognitive mechanisms in problem solving.
The effective problem solving strategy
In the following text we will use the term solution candidate as any sequence of steps the solver can consciously take during the problem solving process.Examples being a particular rotation of Rubik cube, Google search for an existing solution, or drawing a visual representation of a problem and then rubbing out some parts of it.Intuitively, the notion of solution candidate represents a process, method, or idea how to proceed in problem solving, which also includes how the solver generates (or derives, or constructs) and selects the information used in this process.Thus, we have that the same process, method, or idea coupled with different approach to generation or selection of the used information represent different solution candidates.Moreover, we do not require the solver to know how to perform these steps (that can be a different problem on its own), but they should be clear enough to articulate or at least to understand.One can observe that in machine problem solving, a solution candidate is an analogue to a formal string of characters that can be fed to a Turing machine to check as a problem solution.
We realize that this definition of the solution candidates is still a little bit vague but this is probably as concrete as it gets in cognitive psychology.Our defense is that too much formalism can lead to deviation from the actual human problem solving towards machine problem solving.In this sense, let us call by Blind search a method of solving problems by checking all potential solution candidates in no particular order.By potential solution candidates we mean all the solution candidates the solver can think of at some point in the problem solving process.In machine problem solving, this method can solve any problem (provided the problem has a finite solution), although the time required can be huge.The same holds for human problem solving where the solver can, in principle, write down each combination of words, and check if they put together a valid solution.On the other hand, the following Solomonoff strategy presents a probabilistically optimal, i.e., effective, approach with a high chance of finding a solution in a reasonably short time.
Theorem 2.1 (Solomonoff, 1986).Let m 1 , m 2 , m 3 , ... be candidates that can be used to solve a problem.Let p k be probability that the candidate m k will solve the problem, and t k the time required to test this candidate.Then, testing the candidates in the decreasing order pk tk gives the minimal expected time before a solution is found.Remark 2.2.To set things right, this strategy was probably known before Solomonoff used it in his general problem solving system.However, as he did not mention any references regarding this strategy (Theorem I) in his paper (Solomonoff, 1986), or, for that matter, a proof, which can now be found in (Duris, 2016), and we were not able to trace this strategy to any other source, we settled for the term Solomonoff (optimal) problem solving strategy.
It follows that the effectiveness of problem solving depends on (1) the database of solution candidates, i.e., knowledge and experience of the solver, (2) the ability to generate in the effective order (Theorem 2.1) and in a short time the appropriate solution candidates.
Thus, there are differences between human solvers based on their knowledge (Voss, Greene, Post, & Penner, 1983) as well as their cognitive skills (Bassok, 2003).
For this reason, we will talk about the problem solving effectiveness from the solver's perspective rather than the objective effectiveness of the found solution.Therefore, both novice and expert can solve a given problem effectively even though the objective effectiveness of their solutions might be (vastly) different.
The problem solving process is a recursive one, i.e., solving one problem can create new (sub)problems which have their own sets of solution candidates, and the probabilistically fastest way to solve them is again by Solomonoff strategy.We note that Theorem 2.1 assumes that the solver knows the values of p i and t i exactly what is rarely the case in real life.Instead, the solver may only know approximations of these values.For example, he may only know that a particular method is not very reliable, i.e., it has low value p i , or that it is very time consuming, i.e., large value t i .However, this is not necessarily a problem in our theory because the solver usually has, at some point during the problem solving process, only a handful of methods (solution candidates), and this approximate knowledge about such methods can still help him to apply them in the effective order according to Theorem 2.1.Moreover, in the following sections we will argue that human brain has several subconscious abilities to help the solver to generate solution candidates in the effective order even without the explicit knowledge of the values p i and t i .
However, we do not wish to argue that human problem solving is as mathematically optimal as Solomonoff strategy.It is most likely not.Rather, we wish to simply point out that there are several cognitive mechanisms that, on average, seem to drive human problem solving process in the direction similar to that of Theorem 2.1, and, because of this, they are most likely (part of) the source of the effectiveness of human problem solving.For this reason, these mechanisms should be considered for implementation in cognitive architectures aiming at human-like intelligent agents.
Hypothesis 2.3.The following mechanisms play a key part in the effectiveness of human problem solving:
(1) Discovering similarities, (2) Discovering relations or associations, (3) Generalization, (4) Abstraction,
(5) Intuition, (6) Context sensitivity.
In the following six sections we present arguments for each item on the list that it participates in the effectiveness of human problem solving with respect to Theorem 2.1.
Discovering similarities
Fact 3.1.Similar problems often have similar solutions.
A process of solving problems based on the solutions of the similar problems solved in the past is also called Case-based reasoning (Slade, 1991).The Fact 3.1 is used by everyone on a daily basis to quickly solve many situations in life, work, etc.It is not hard to see that it also fits perfectly with the Solomonoff strategy.More particularly, the solver identifies a set of problem concepts (properties, features, structure etc.) based on which he can quickly access similar concepts stored in his memory that are associated with an idea how to solve a known problem.In such a case the new problem and the known one are similar via this set of concepts.According to the Fact 3.1, this process provides the solver with highly relevant solution candidates (i.e., with relatively high values p i /t i ), and, vice versa, the solution candidates that are not similar with the current problem are not recalled in this way.Moreover, it was observed that humans have cognitive abilities that support effective search for similarities and patterns (Bejar, Chaffin, & Embretso, 1991;Gentner, Rattermann, & Forbus, 1993;Robertson, 2003).Thus, this process is relatively quick and often successful, which is in accord with (ii) above.
Discovering relations or associations
Fact 4.1.Related facts, problems or situations (i.e., relevant information) often hold the clues for the solution of the problem.
A problem involving a right triangle can fire up an association with the Pythagorean theorem which can be used in search of a solution (the right triangle and the Pythagorean theorem are closely related but not really similar).Altshuller (1994) developed TRIZ, a general strategy for creative problem solving, that exploits already solved problems to suggest new solution candidates, and other authors also rely on finding related problems and situations in their problem solving strategies (Polya, 1957;Woods, 2000).
Clearly, related facts, problems, situations, experiences etc. (i.e., relevant information) often hold crucial clues for the solution of the current problem without which the solver would get stuck.Interestingly, human brain seems to be wired in a way not only to store concepts but also relationships among them.Thus, it is able to support quick retrieval of highly relevant information (not necessarily similar as in Section 3).Evolutionary benefits of such case are obvious, and there is a solid theoretical support for it.A semantic network is a well established model of the long term memory (A.M. Collins & Quillian, 1969;Quillian, 1968).Concepts, representing knowledge and experience are joined by associations of potentially different weight.Concepts are activated by a process of spreading activation from the already active concepts through their weighted associations (J.R. Anderson, 1983;A. Collins & Loftus, 1975;Ohlsson, 1992).The adjustments of the weights of the associations as well as their creation/deletion (forgetting) is accomplished based on the Hebb rule (Hebb, 1949).It follows that by this rule we have the strongest associations among the most related concepts which again fits with the Solomonoff strategy.More precisely, the ability of human brain to quickly retrieve relevant information together with Fact 4.1 mean that the solver has relatively quick access to relevant information which often contain crucial information for the solution, and with which the solver can more easily and quickly solve the problem.Such approach to problem solving is thus often quick and successful, and by this it is in accord with (ii) above.
Observe also that even though human brain is a vast storage of various interconnected knowledge and experiences, by Hebb rule there are no strong connections between totally unrelated concepts.In this way, the human brain instantaneously filters out huge amounts of information which are most likely unimportant for the solution of the current problem.This may not be always the case, but recall that the Solomonoff strategy is probabilistic.
Generalization
It was observed that humans are more likely to remember only the crucial parts of information or experience rather than specific details (Censor, 2013;Xu & Südhof, 2013).In this sense, we are more likely to remember crucial steps in a complicated construction like a mathematical proof rather than the exact details.On one hand, it is inefficient to store too much information that can be easily filled in on-demand.On the other hand, proofs reduced to a few key steps are more likely to fit other problems as well.For example, dynamic programming originated as a solution to one particular problem but in time it was generalized to a paradigm applicable on a whole range of different problems.Thus, generalization helps human solvers to overcome the threshold of similarity (between two problems, or, in general, two concepts) by reducing the number of parts that needs to fit which in turn helps the effectiveness of problem solving by the same reason as discovering similarities.
Furthermore, we can imagine problem solving as browsing an association tree where we have information associated with the identified problem properties.By browsing such tree, we are trying to find some crucial information for the solution.In case of ungeneralized specific past problems, solutions, proofs etc. we would browse large trees full of unimportant details which can take a long time.By generalization, we can prune these trees to much smaller thus making problem solving faster, i.e., more effective.Of course, we may not find the right information always, but by Solomonoff strategy it pays, on average, to check the most promising information (i.e., candidates) first.
Abstraction
Fact 6.1.Problems with the same gist/structure often have the same or a similar solution.
Abstraction is extracting from a given problem representation only those features that are related to the essence of the problem, i.e., its general pattern (Adler, 1984).
For example, computing the life expectancy of a fly that is zig-zagging between two trains going in the opposite direction is in fact a simple "distance = speed x time" problem, if we abstract from the shape of the fly's trajectory.In this sense, working with abstractions reduces the problem space as many problems coalesce into one abstract version.On one hand, using the reduced (i.e., abstract) problem space allows more effective comparisons between the problems.On the other hand, it helps human solvers to further overcome the threshold of similarity (between two problems, or, in general, two concepts) because superficially different problems can be classified as similar on a deeper level.Thus, abstraction connects the human problem solving effectiveness with the effective Solomonoff strategy, and improves the problem solving effectiveness by the same way as does discovering similarity and generalization described in Sections 3 and 5 above.
Moreover, abstraction enables the solver to direct his focus on the essential features of the problem instead of surface details.In this way, the solver does not waste time by exploring irrelevant (e.g., surface) problem features or associations, i.e., weak solution candidates.As was the case with generalization, this may not always work, i.e., it is a bet.But, according to the Fact 6.1, it is a bet with a good chance of success.
Intuition
The role of intuition in problem solving and decision making is undeniable (Dorfman, Shames, & Kihlstrom, 1996;Lufityanto, Donkin, & Pearson, 2016;Metcalfe & Wiebe, 1987;Pretz, 2008;Style, 1979).However, we do not mean to discuss how does it work here.For our purposes, intuition is something similar to a preschool child learning a grammar.The child can use the rules mostly correctly, but he or she cannot formulate them.However, the rules are in some accessible way stored in the child's memory.In this way, intuition provides the solver with candidates to test or associations to follow even though the solver cannot articulate the reasons why he should do so (i.e., such candidates may not appear to the solver visibly similar or related to the current problem).In words of Nelissen (2013), problem solver -using the available, compacted knowledge -is aware of the direction in which the thinking process should proceed and what kind of information and knowledge can be relevant.Thus, it follows that intuition connects the human problem solving with the effective Solomonoff strategy as does discovering similarities and relations/associations described in Sections 3 and 4 above.
Context sensitivity
Concepts in solver's memory have, in general, many associations (Ohlsson, 1992), and each such association with the given problem is a potential solution candidate.However, those candidates that do not fit the context in which the problem is set are probably not going to be part of the solution.Imagine again the problem solving as browsing an associations tree where we have information associated with the identified problem properties.By (temporarily) blocking the associations that do not fit the context, the association tree in which the solver is searching for a crucial information is pruned.In other words, the solver's focus is directed to the most promising associations (solution candidates).This again fits with the Solomonoff strategy that candidates most likely to succeed are checked first.
Conclusion
We proposed a connection between six well-known cognitive mechanisms (discovering similarities, discovering relations or associations, generalization, abstraction, intuition, context sensitivity) and Solomonoff optimal problem solving strategy, which states that if there are multiple approaches to finding a solution to the problem, then one should start with the most promising approach first (of course, respecting application times of the approaches as well).In this paper, we put forward arguments that these six mechanisms drive human problem solving in the very similar manner, which may be the first explicit argument for the effectiveness of human problem solving.We stress again that the effectiveness is meant from the solver's perspective (i.e., given his knowledge and the state of his cognitive skills).Thus, both novice and expert can solve a given problem effectively even though the objective effectiveness of their solutions might be (vastly) different.
Furthermore, the presented mechanisms are those for which we found a direct relation with the Solomonoff strategy.However, this does not imply that these six mechanisms act alone in the process of solving problems.They are supported by cognitive facilities for language processing, working memory system for coordinating, monitoring and executing the intended actions, long-term memory system for retrieval and interpretation of memories and experiences and so on.
Also, Cassimatis (2006) proposed an idea that only a few cognitive mechanisms are needed to explain the domain-universal human intelligence.His initial guess what such mechanisms could be includes reasoning about time, space, parthood, categories, causation, uncertainty, belief, and desire.While they do not match our list from Hypothesis 2.3 (Cassimatis talks about the domain-universal human intelligence, not the effectiveness of problem solving), they give support to the idea that effective problem solving does not need to entail overly complex models.
The presented results in this paper can serve two purposes.First, based on this preliminary work, we can start building a more robust understanding of how people solve problems effectively.In this sense, we can further research the following issues.Is the set of mechanisms in Hypothesis 2.3 complete?Given some support processes (e.g., language processing, working and long-term memory processes), how large role do mechanisms from Hypothesis 2.3 play in problem solving?Are there any other key mechanisms in problem solving which we did not cover?Second, proper understanding of principles behind the effectiveness of human problem solving can help the design of cognitive architectures (or AI generally) to develop agents with more human-like abilities.If some cognitive architectures already support some of these mechanisms, then this work can act as an argument about their problem solving effectiveness.
Abstraction is uncooperative. J E Adler, Journal for the Theory of Social Behaviour. 1421984
The Art of Inventing (And Suddenly the Inventor Appeared). G Altshuller, 1994Technical Innovation CenterWorcester, MA
ACT: A simple theory of complex cognition. J Anderson, American Psychologist. 5141996
An integrated Theory of the Mind. J Anderson, D Bothell, M Byrne, S Douglass, C Lebiere, Y Qin, Psychological review. 1112004
A spreading activation theory of memory. J R Anderson, Journal of verbal learning and verbal behavior. 2231983
Analogical Transfer in Problem Solving. M Bassok, The Psychology of Problem Solving. R Sternberg, J E Davidson, Cambridge University Press2003
Cognitive and psychometric analysis of analogical problem solving. I Bejar, R Chaffin, S Embretso, 1991Springer-VerlagNew York
A cognitive substrate for achieving human-level intelligence. N Cassimatis, AI magazine. 2722006
Generalization of perceptual and motor learning: a causal link with memory encoding and consolidation?. N Censor, Neuroscience. 2502013
A spreading activation theory of semantic processing. A Collins, E Loftus, Psychological Review. 821975
Retrieval time from semantic memory. A M Collins, M R Quillian, Journal of verbal learning and verbal behavior. 821969
The suddenness of insight. J Davidson, R.J.Sternberg and J.E.Davidson1995Cambridge University PressNew YorkThe nature of insight
Insights about insightful problem solving. J Davidson, Psychology of problem solving. R J Sternberg, J E Davidson, Cambridge University Press2003
The role of insight in intellectual giftedness. J Davidson, R Sternberg, 198628
Intuition, incubation, and insight: Implicit cognition in problem solving. J Dorfman, V A Shames, J F Kihlstrom, Implicit cognition. 1996
Cognitive architectures: Where do we go from here. W Duch, R Oentaryo, M Pasquire, AGI. 1712008
Error bounds on the probabilistically optimal problem solving strategy. F Duris, Acta Mathematica Universitatis Comenianae. 2016
Automatic Evaluation and Selection of Problem-Solving Methods: Theory and Experiments. E Fink, Journal of Experimental and Theoretical Artificial Intelligence. 1622004
The roles of similarity in transfer: Separating retrievability from inferential soundness. D Gentner, M Rattermann, K Forbus, Cognitive Psychology. 251993
The organization of behaviour: A neuropsychological theory. D Hebb, 1949WileyNew York
Distributed representation of structure: A theory of analogical access and mapping. J Hummel, K Holyoak, Psychological review. 1041997
The fastest and shortest algorithm for all well-defined problems. M Hutter, International Journal of Foundations of Computer Science. 03132002
Universal artificial intelligence: Sequential decisions based on algorithmic probability. M Hutter, 2005Springer Science & Business Media
An architectural framework for complex cognition. U Kurup, P Bignoli, J Scally, N Cassimatis, Cognitive Systems Research. 1232011
Extending the Soar cognitive architecture. J Laird, Frontiers in Artificial Intelligence and Applications. 1712008
A unified cognitive architecture for physical agent. P Langley, D Choi, Proceedings of the National Conference on Artificial Intelligence. the National Conference on Artificial Intelligence200621
Cognitive architectures: Research issues and challenge. P Langley, J Laird, S Rogers, Cognitive Systems Research. 1022009
An Extended Theory of Human Problem Solving. P Langley, S Rogers, Proceedings of the twenty-seventh annual meeting of the cognitive science society. the twenty-seventh annual meeting of the cognitive science society2005
Elaborations on a Theory of Human Problem Solving. P Langley, N Trivedi, Poster Collection: The Second Annual Conference on Advances in Cognitive Systems. 2013
Measuring intuition nonconscious emotional information boosts decision accuracy and confidence. G Lufityanto, C Donkin, J Pearson, Psychological science. 2752016
Intuition in insight and noninsight problem solving. J Metcalfe, D Wiebe, Memory & cognition. 1531987
Soar-RL: Integrating reinforcement learning with Soar. S Nason, J Laird, Cognitive Systems Research. 612005
Intuition and problem solving. J Nelissen, Curriculum and Teaching. 2822013
Information processing explanations of insight and related phenomena. S Ohlsson, Advances in psychology of thinking. M T Keane, K J Gilhooly, Cambridge, MAHarvard University Press1992
How to solve it. G Polya, Artificial intelligence: foundations of computational agents. D L Poole, A K Mackworth, Doubleday, Garden City, NYCambridge University Press1957. 2010second edition
Intuition versus analysis: Strategy and experience in complex everyday problem solving. J E Pretz, Memory & cognition. 3632008
Semantic information processing. M Quillian, M.Minsky1968MIT PressCambridge, MASemantic memory
Problem Solving: Problem similarity. S Robertson, 2003Psychology Press
Optimal ordered problem solver. J Schmidhuber, Machine Learning. 200454
Case-based reasoning: A research paradigm. S Slade, AI magazine. 1211991
The Application Of Algorithmic Probability to Problems in Artificial Intelligence. R Solomonoff, Uncertainty in Artificial Intelligence. L.N.Kanal and J.F.Lemmer1986Elsevier Science Publishers B.V
Intuition and problem solving. A Style, JR Coll Gen Pract. 291991979
Problem-solving skill in the social sciences. J F Voss, T R Greene, T A Post, B C Penner, Psychology of learning and motivation. 171983
Metacognition and insight during problem solving: Comment on Metcalfe. R Weisberg, Journal of experimental psychology: Learning, memory, and cognition. 199218
An Evidence-Based Strategy for Problem Solving. D Woods, Journal of Engineering Education. 892000
A neural circuit for memory specificity and generalization. W Xu, T C Südhof, Science. 33961252013
| [
-0.03722376376390457,
0.0627799779176712,
0.0172685869038105,
-0.07017648220062256,
-0.044458456337451935,
-0.07261151075363159,
0.07046119123697281,
0.08298874646425247,
0.09467695653438568,
0.1640360951423645,
-0.12319666147232056,
-0.07111011445522308,
0.015593202784657478,
0.1517845392... |
ProfZbigniew Jan
Szczyglowski
ProfAalborg Zhe Chen
Denmark Prof Universitet
Nuno Ricardo
Soares Madeira
Branco
ProfAssoc Jaroslaw Krzywanski
Jan
ProfAssoc Khamaruzaman
Wan Yusof
Universiti Teknologi
Petronas Malaysia
ProfMalaysia Assoc
Malinee Sriariyanun
North Bangkok
ProfThailand Fangyu Assoc
Fan
ProfAssoc
FengHsiu-Hua Chang
Chia Universtity
ProfTaiwan Montri Assoc
Wiboonrat
ProfAssoc Suhana Binti
Mohd Said
ProfAssoc Nilofar Asim
Universiti Kebangsaan Malaysia
Prof. MdMalaysia Assoc
Universiti Akhtaruzzaman
Malaysia Kebangsaan Malaysia
ProfFangyu Assoc
Fan
ProfAsst
DrHassan Ali
DrZhang Zijun
Czestochowa University of Technology
Poland
University of Coimbra
CoimbraPortugal
King Mongkut's
Dlugosz University
CzestochowaPoland
King Mongkut's Institute of Technology Ladkrabang
University of Technology
Southwest Forestry University
China, Thailand
University of Malaya
Malaysia
Southwest Forestry University
China
University of Newcastle
Australia
City University of Hong Kong
Hong Kong
Chinese Academy of Sciences
China (Tohoku10.1088/1755-1315/551/1/011002Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 2020 the 3rd Asia Conference on Energy and Electrical Engineering IOP Conf. Series: Earth and Environmental Science 551 (2020) 011002 IOP Publishing 1 University, Japan) Professor Ir. Dr. Ab. Halim Bin Abu Bakar, University of Malaya, Malaysia Conference Program Chair Dr. Zhizhi Wang, Shandong University, China Conference Publicity Chair Assoc. Prof. Nurdan YILDIRIM, Yasar University, Turkey Conference Technical Committees Prof. Silvia Brunoro, University of Ferrara, Italy Prof. dr hab. inż. Andrzej Kapłon, Kielce University of Technology, Prof. Florinda Martins, Instituto Superior De Engenharia Do Porto, Portugal Prof. Chun-Ching Hsiao, National Formosa University, Taiwan Prof. Om Malik, University of Calgary, Canada Prof. Laurent Linguet, University of French Guiana, French Guiana Prof. Ming-Ta Yang, St. John's University, New Taipei city, Taiwan Prof. Sanjay Deokar, Zeal College of Engineering and Research, India Prof. Abdullah Al-Odienat, Department of Electrical Engineering Mutah university, Jordan 2020 the 3rd Asia Conference on Energy and Electrical Engineering IOP Conf. Series: Earth and Environmental Science 551 (2020) 011002 IOP Publishing 2 Asst. Prof. Kanesan Muthusamy, UCSI University, Malaysia Asst. Prof. Muhammad Raza Ul Mustafa, Universiti Teknologi PETRONAS Malaysia, Malaysia Asst. Prof. Yuhiro Iwamoto, Nagoya Institute of Technology, Japan Asst. Prof. Haruhiko Yamasaki, Osaka Prefecture University, Japan Asst. Prof. Chodchanok Attaphong, King Mongkut's Institute of Technology Ladkrabang, Thailand Asst. Prof. Chunhua Liu, City Unviersity of Hong Kong, Hong Kong Dr. Biao Shen, Kyushu University, Japan Dr. Yongchang Feng, Tohoku University, Japan Dr. Jaroslaw Rolek, Kielce University of Technology, Poland Dr. Hongwei WU, University of Hertfordshire, UK Dr. Farhad SHAHNIA, Murdoch University, Australia Dr. Francisco Gonzalez-Longatt, Loughborough University, UK Dr. Emin Selahattin UMDU, Yasar University, Turkey Dr. Naga Prapurna Pentapati, Chaitanya Bharathi Institute of Technology, India Dr. Chethika Abenayake, University of Moratuwa, Sri Lanka Dr. Choolaka Hewawasam, University of Sri Jayawardhenepura, Sri Lanka Dr. Amila Jayasinghe, University of Moratuwa, Sri Lanka Dr. Jeff Kilby, Auckland University of Technology (AUT), New Zealand Dr. Fengji Luo, The University of Sydney, Australia Dr. Masita Mohammad, Universiti Kebangsaan Malaysia, Malaysia Dr. Olowoleni, Joseph Oluwole, Covenant University, Nigeria Dr. Ademola Abdulkareem, Covenant University, Nigeria Dr. Adeyinka A. Adewale, Covenant University, Nigeria Dr. Nnadi Damian Benneth, University of Nigeria, Nigeria Dr. Chibuzo Joseph Nnonyelu, University of Nigeria, Nigeria Dr. Isaac Adekunle Samuel, Covenant University, Nigeria
| [
-0.09054930508136749,
0.08146997541189194,
0.058462876826524734,
0.03961769491434097,
0.16678491234779358,
-0.20430871844291687,
-0.07107837498188019,
-0.012947103008627892,
0.03833078220486641,
0.06006915122270584,
-0.005709795281291008,
-0.034749940037727356,
0.0385894812643528,
-0.00101... |
Control Intractable Pain
Control Intractable Pain
Single Cancer Cell .
The possibility that a single cancer cell may be more deadly than an en tire clump of them is being explored by Hauschka (Institute for Cancer Re search, Philadelphia).
He has been growing single ascites cells in hanging drops to produce genetically pure clones for his experiments. Preliminary experiments indicated that four or five cellsâ€"some of them damaged in han dlingâ€"were thoroughly able to pro duce more rapidly growing tumors than those developing from standard trans plants. Now he is injecting animals with single cellsâ€"he knows they are single cells because he can count them in pipettes under the microscopeâ€"to test their takes. It is conceivable that clusters of cells that are genetically dif Intractable pain, a common conse quence of head and neck cancers, has been controlled completely in six pa tients experimentally treated with frontal lobe injections of procaine at the University of Pennsylvania Hos pital. Grant and Nulsen found that the injections gave rapid and lasting relief and constituted, in effect, a â€oe¿ chemical lobotomy.― The patients acknowledged being aware of the existence of pain, but they asserted that they were not dis tressed by it. More important, anticipa tion of pain and anxiety were banished; and all patients were able to view their medical hopelessness and inevitable ends with serene objectivity. Current experiments are designed to calculate the duration of relief per unit of drug. Some injections afforded relief for weeks. Second injections were more ef fective than the first.
Radiogold and Prostate .
Flocks and others (State University of Iowa) have injected radiogold inter stitially into 160 prostatic cancers during the last twenty months and have achieved apparently complete (but possibly temporary) remissions in 87 in cancer new ferent may contain a common antigen that would stimulate vigorous antibody reaction, whereas a single cell may stir a slighter immune response.
Estrogen Excretion . Nathanson and Engel (Massachu setts General and Harvard) have found that androgens given to breast and pro static-cancer patients are excreted as estrogens. Chemical, even commercial, synthesis of estrogen from androgen is feasible. But this is the first time that the alterations have been detected in nature. The results resurrect an old and highly speculative ideaâ€"but this time with some basis of proofâ€"that thenormalor abnormalsystemiscap able of transforming one sex hor mone into another. These are among the early observations of techniques (counter-current distribution, chroma tography, and lysis by enzymes) re cently perfected and now being applied tourinary studies of patients.
Terramycin Warning -
Klopp and others (George Washing ton) have reported that terramycin in large doses may be dangerous to de bilitated patients.
Eight of ten ad vanced cancer patients seem to have died prematurely after large (but, ac cording to the literature, safe) doses. Studies showed they developed pro nounced lethargy, avid thirst, and a shocklike condition. Blood levels of the drug continued to rise with each suc ceeding dose. Terramycin was used in line with experimental antibiotic treat ment of terminal patients. The George Washington team have achieved very good results against some cancers with aureomycin and radiation.
Infrared Snapshots .
The simple technique of making infrared snapshots has shown up some cases of breast cancer in experiments at Marquette. Massopust, the photog rapher, has made pictures of the breasts of 1600 cancer suspects, found seventy cases of cancer and missed four. De terminations were based upon the vas cular patterns that are brought out clearly on infra red film (the rays penetrate the skin about 2 mm.). In terrupted or engorged veins indicated cancer. Regular photographic equip ment plus an infrared filter and film were used.
Myeloid Metaplasia --
Experience by Block and Jacobson (Chicago) indicates that many (20 to 50 per cent) patients diagnosed as having hopeless and malignant chronic myelogenous leukemia may have non malignant myeloid metaplasia, which offers a life expectancy of ten to thirty years. Moreover, some of the measures taken to manage the leuke mia (radiation and splenectomy) may terminate the lives of myeloid-meta plasia patients within a few months. The studies showed that every case diagnosed as leukemia following poly cythemia vera was, in fact, myeloid metaplasia. The scientists have reported that one sure method of differential diagnosis is spleen biopsy.
Adrenalectomy .
Huggins (Chicago U.) notes these results after eighty bilateral adrenalec tomies: about one half the cases of cancerof thebreast and prostateâ€"no other types so farâ€"are benefited by the operation. Patients can be maintained satisfactorily with small daily doses of cortisone. Ovariectomized and adrena lectomized patients who were not helped continue to excrete estrogen products.
These results suggest that traditional concepts of the sources of adrenal hormones and estrogen be re examined. Some of the white-haired male patients developed iron-gray hair following adrenalectomy; and many of them reported losing their habitual anxieties and angers.
| [
-0.022632930427789688,
-0.022491976618766785,
-0.07568072527647018,
0.036389850080013275,
-0.13003572821617126,
-0.07047010958194733,
0.04100567102432251,
0.18282312154769897,
0.0844549685716629,
0.10083293914794922,
0.001291214139200747,
0.02554924227297306,
0.08054199814796448,
-0.021690... |
N Singh
M.DM B B S
G Patel
Y Dogra
S Mohanty
T Seth
citation ID: deac107.731 P-795 Comparison of intra-ovarian platelet rich plasma versus autologous bone marrow derived stem cell instillation in women with diminished ovarian reserve for ovarian rejuvenation
Study question: To compare role of intra-ovarian platelet rich plasma (PRP) versus marrow derived stem cell (SC) instillation for improvement in ovarian reserve (AFC, AMH and FSH) Summary answer: Both PRP and SC therapy improves the ovarian reserve however, response to PRP is superior to SC post intervention What is known already: With increasing incidence of females with diminished ovarian reserve (DOR), posing a serious challenge in terms of limited treatment options for these couples. Clinicians are trying to find effective strategies besides oocyte donation or adoption Of late, novel ovarian rejuvenation approaches has been investigated which are currently available for research purposes only. Multiple studies are evaluating effect of intra-ovarian PRP or autologous SC instillation, the results are encouraging as they are showing improvement in ovarian reserve thus bringing a paradigm shift in treatment options. None of the published studies so far have compared PRP versus SC in DOR population. Study design, size, duration: A prospective comparative study was conducted at Division of Reproductive Medicine of a tertiary care institute. 72 infertile females (20-39 years) with poor ovarian reserve (AMH <1.2 ng /ml; AFC<5) were enrolled in the study between January 2020 to December 2021. The two comparative groups underwent either intra-ovarian PRP instillation (n ¼ 42) or autologous SC transplantation (n ¼ 30). Participants/materials, setting, methods: After the two groups were matched (PRP vs SC) for baseline characteristics (Age, AMH, AFC, FSH, Estradiol), 30 subjects in each group were compared for change in serum FSH/AMH/Estradiol levels, AFC, right and left ovarian volume at 1 st month and 3 rd month post intervention from the baseline. This was also compared between the two groups using Student t-test. The cost and procedural pain measured using Visual analog scale (VAS) were also compared between the groups. Main results and the role of chance: After matching for baseline characteristics, significant $ 1.8/2 and $1.5/1.6 fold increase in AFC at 1 st /3 rd month post intervention (p<0.001) was observed after PRP instillation and SC transplantation respectively. This significant improvement was observed more in PRP group than SC group at 3 rd month post intervention (7.07 vs 5.60, p¼0.02), while no significant difference existed at 1 st month of follow up. However, there was no significant improvement in serum FSH, AMH and Estradiol levels (p0.05) from the baseline at 1 st and 3 rd month post intervention in both the groups. Similarly, there was no significant difference between the two groups in serum FSH level (7.98 IU/ml vs 9.62 IU/ml, p¼0.062; 8.26 IU/ml vs 9.50 IU/ml, p¼0.15), AMH level (1.62 ng/ml vs 1.02 ng/ml, p¼0.27; 1.35 ng/ml vs 0.95 ng/ml, p¼0.24), Estradiol level (49.12 pg/ml vs 56.48 pg/ml p¼0.443; 54.7 pg/ml vs 61.12 pg/ml, p¼0.44), right ovarian volume (3.13 cm 3 vs 2.49 cm 3 , p¼0.06; 3.37 cm 3 vs 2.74 cm 3 ,p¼0.063) and left ovarian volume (2.98 cm 3 vs 2.47 cm 3 , p¼0.102; 2.87 cm 3 vs 2.34 cm 3 ,p¼0.103) at 1 st and 3 rd month post intervention respectively. PRP was more cost-effective and associated with less pain (32.5 mm vs 28.13 mm, p¼0.02), and better patient compliance. Limitations, reasons for caution: This was a comparative study and the participants were not randomized but were matched for the baseline characteristics. Also due to impact of Covid-19 causing intermittent pause in nonessential facilities like IVF services, a smaller sample size could be enrolled and also clinical outcomes could not be evaluated Wider implications of the findings: This study, although comparative, for the first time highlights the beneficial role of PRP over SC, thus can establish superiority of PRP as minimally invasive, economical, patient friendly and a recommended therapy for ovarian rejuvenation and folliculogenesis, providing the DOR females an opportunity to produce their own offspring. Trial registration number: CTRI/2020/01/022726 38th Hybrid Annual Meeting of the ESHRE, Milan -Italy, 3-6 July 2022 i561
| [
-0.01287706196308136,
-0.09687143564224243,
0.007760779466480017,
0.04939906671643257,
-0.09830266982316971,
0.021654989570379257,
-0.09716964513063431,
0.24239134788513184,
0.16840983927249908,
0.09182481467723846,
0.03188319504261017,
0.132500559091568,
0.0032909505534917116,
-0.01014145... |
Medical chemistry must loom large as one of the earliest roots of chemical physiology, or biochemistry. Despite its importance today, chemistry was relegated to the very periphery of medical science until well into the nineteenth century. Analysis of body fluids yielded little of medical value until they could be fitted into a perspective of healthy metabolism. Rather, such informationif seen not only as an attempt to diagnose disease but also to explain itcould only represent a kind of appendix to pathological anatomy, "put there for the sake of symmetry, a painted window from a false edifice" (Pettenkofer to Liebig, 1849). Ludwig Thudichum, the chemically orientated clinician and founder of the ill-fated Annals ofChemical Medicine (1879Medicine ( , 1881, believed that no pathology was possible before a full analysis of all the body tissues in their healthy state had been achieved. His slow, but enormously detailed results, a molecular sieving of the body's chemistry, were not enthusiastically received. Under attack in 1869, he wrote, "I feel myself in this position, put with an excellent needle-gun to take an armour-clad steam-vessel. Such is the proportion of my means to the problem to be solved."
In the History of clinical chemistry, Professor Buttner has brought together an important collection of eight essays dealing with the subject's development in the nineteenth and twentieth centuries. All the essays were previously published in the Journal of Clinical Chemistry and Clinical Biochemistry. The interplay of clinical chemistry and biochemistry is underlined in an excellent contribution by J. S. Fruton. As well as rewarding pieces on instrumentation and the evolution of clinical enzymology, there are additions to our biographical knowledge in Hans Simmer's impressive article on Eugen von Gorup-Besanez (1817-1878, and in Buttner's piece on J. J. von Scherer (1814-1869). Like all stimulating books, this makes one ask new questions, in the light of what one has read. Certainly what is needed now is a comparable account of clinical chemistry in the English and French medical contexts. (The essays confine themselves in the main to the German-speaking countries.) Another question opened up by this volume is the changing inter-relationship between clinical chemistry (chemical pathology) and bacteriology in the crucial decades of the 1 880s and 1 890s.
The book is a little spoiled by some typographical errors, but a more serious flaw is the lack of a useful index ("pupils of Liebig" under "P" and "contributions to physiological and pathological chemistry" under "C", are examples of its quaintness).
In his Introduction, Buttner points out the unfortunate consequences for the history of science that flow from picturing "clinical chemistry" as simply a post-war specialization (First International Congress, 1954). I presume that Buttner prefers to see it as a member of what Robert Kohler has called "the timeless, extended family of biochemistries", which has differentiated itself over time. In any case, Buttner's aim of stimulating interest in the history of clinical chemistry and related areas will be furthered by this volume.
Neil Morgan Wellcome Institute KARL HUFBAUER, The formation of the German chemical community (1720-1795),
Berkeley, Los Angeles, and London, University of California Press, 1982, 8vo, pp. viii, 312, illus., £34.00 (£12.75 paperback). Several of the independent states that constituted eighteenth-century Germany had academies or universities where chemistry flourished, particularly in medical faculties. German chemists have received inadequate attention from historians of the period, but Professor Karl Hufbauer now remedies this situation with a remarkable book that is an important contribution to both scientific and social history.
Chemistry received official support because of its utility in medicine and, to a lesser extent, mining and manufacture, and Hufbauer shows that between 1720 and 1780 the number of salaried posts for chemists in medical schools increased from six to twenty-eight. Most professors were doing research and publishing, though their patrons expected them only to teach, and they eventually formed a nationwide community.
In 1778, Lorenz Crell, professor at Helmstedt, realized that he could benefit this community and advance his own career by founding a specialized chemical journal. Under various titles Crell's Annalen prospered. By 1789, it had attained a circulation of over seven hundred, and Crell had been elected to more than twenty societies. In 1789, German chemists began to accept Lavoisier's antiphlogistic theory, and Hufbauer gives us the first full account of the controversy that divided them during the next four years. By 1793, only a handful were still phlogistians; among them was Crell, who found himself almost excluded from the community he had served so well.
Hufbauer's narrative fills only half the book. The rest contains concise but extremely welldocumented and informative biographies of sixty-four chemists and histories of fifty-five institutions. Crell's Annalen had more than a hundred subscribers outside Germany, showing that there was a truly international chemical community by the end of the century. This book is therefore recommended to all historians of eighteenth-century chemistry and not merely to those with a special interest in Germany.
W. A. Smeaton
University College London JOHN FARLEY, Gametes and spores. Ideas about sexual reproduction 1750-1914, Baltimore, Md., and London, Johns Hopkins University Press, 1982. Professor Farley has written an absorbing sequel to his earlier The spontaneous generation controversy from Descartes to Oparin. In ten closely-referenced chapters he follows the growth of our understanding of sexual reproduction from Linnaeus in the 1750s to Thomas Hunt Morgan's 1913 Heredity and sex and Frank Lillie's 1914 paper on fertilization.
It is salutary to look back over the long tide of history and recognize how very difficult it has been to establish what is now taken for granted in every school textbook of biology. John Farley leads us far away from parochial concerns with human sexual reproduction. He shows that the scientific arguments were lost and won on the farther shores of cryptogamic botany and invertebrate zoology. It was through researches on these still somewhat disregarded organisms that our modern understanding of sexual reproduction and its biological significance was ultimately gained. But medical readers should be warned: Homo sapiens does not figure largely in this book.
But Farley does more than merely recount the internal history of the discovery of gametes and spores. He also sets the evolving science in its social context. In one of his most interesting chapters, he examines the effect eighteenthand nineteenth-century social attitudes had on the biological study and interpretation of reproduction. He also follows families of scientific investigators, showing how personal influences spread from laboratory to laboratory and from land to land. He is especially interesting on the spread of the experimental method in botany and how this eventually reached Cambridge in the 1870s, where the science was "moribund in the summer and actually dead in the winter", and also on the complex story of the tardy and patchy take-up of Mendel's work by cytologists and physiologists in the early 1 900s.
After reading Farley's book, one is forcibly reminded of Newton's famous observation that if he had seen further than others it was because he had stood upon the shoulders of giants and, perhaps even more forcibly, of his other remark in which he likens himself to a child collecting shells on the beach with the ocean of truth still undiscovered before him. For after leading us through the tangled web of nearly two centuries of research and controversy, after describing the discoveries and mistakes of innumerable investigators, both famous and obscure, Farley ends with a postscript in which he argues that "sex remains almost as complete an enigma today as it was three hundred years ago when Dutch microscopists discovered minute 'animalcules' swimming about in human seminal fluid".
Gametes and Spores is a book which widens and deepens one's understanding of contemporary biology as well as recording its history. If the past has anything to teach the present, it is that only painstaking detailed research and controversy are capable of answering the questions that confront us. We still have far to go. Professor Farley has provided us with a book, well referenced, illustrated, and indexed, which will help us on that journey. C. U. M. Smith
University of Aston in Birmingham
| [
-0.10895462334156036,
-0.019425928592681885,
-0.09433235973119736,
-0.003534572897478938,
-0.09660162031650543,
0.02862531691789627,
0.03462556004524231,
0.3345898389816284,
-0.054426729679107666,
-0.05118906870484352,
-0.13260358572006226,
0.04398709535598755,
0.02593103051185608,
0.08810... |
Sagittal sinus thrombosis secondary to varicella infection-a case report
November-December 2017. 1693. 2017 Dec
Gurinder Mohan
Harharpreet Kaur
Navjot Kaur
Sagittal sinus thrombosis secondary to varicella infection-a case report
International Journal of Advances in Medicine Gurinder M et al. Int J Adv Med
46November-December 2017. 1693. 2017 Dec10.18203/2349-3933.ijam20175193Case Report
Varicella zoster virus (VZV) is known to produce a benign self-limiting exanthematous illness in the pediatric population. The neurological complications which are seen in less than 1% cases include cerebellitis and encephalitis. Stroke due to arterial vasculitis is well known but cerebral venous sinus thrombosis following varicella infection is rarely reported. We present a case of sagittal sinus thrombosis subsequent to varicella infection. The mechanisms underlying cerebral vascular events after VZV infection could be vasculitis, thrombosis due to direct endothelial damage and acquired protein S deficiency.
INTRODUCTION
Chicken pox produces a benign self-limited disease in children. Varicella-related neurological complications are seen in less than 1% cases of chickenpox. The most frequently encountered are cerebellitis and encephalitis. Aseptic meningitis, Guillain-Barre syndrome and transverse myelitis are relatively less common. VZV cerebral vasculopathy can occur after a primary varicella infection or zoster. Most of the earlier literature on VZV vasculopathy describes it as a disease affecting predominantly large arteries causing strokes and transient ischemic attack. The occurrence of cerebral venous sinus thrombosis (CVST) following primary Varicella Zoster infection is very rare. We report a case of sagittal sinus thrombosis secondary to varicella infection.
CASE REPORT
Our patient was a 20-year-old previously healthy male who presented in the emergency room with history of generalized tonic clonic seizures and altered sensorium. It was preceded by fever and severe headache. 15 days back he had developed rash typical of chickenpox on the trunk and the limbs. Systemic examination revealed residual scars and crusting lesions. Fundus showed bilateral papilloedema. Motor system examination showed weakness of left upper and lower limb (grade 1-2) with left extensor planter response. Routine hemogram and serum biochemistry were normal.
MRI showed a large irregular hyperintense lesion in the right front parietal lobe superiorly. Haemorrhagic changes were observed in it. A similar lesion was identified in the left frontal lobe posterosuperiorly. There was loss of normal flow void in the superior sagital sinus. The picture was suggestive of haemorrhagic infarcts with diffuse cerebral swelling secondary to thrombosis of superior sagittal sinus ( Figure 1).
Positive varicella antibodies were detected in the serum and CSF. The patient was given decongestive antiedema therapy, injectable acyclovir and antiepileptics. Low molecular weight heparin was initially withheld but started later. He improved gradually over the next two weeks and was discharged on oral anticoagulants. After 6 months the patient can walk with a limp though the upper limb is still not fully functional especially the hand.
DISCUSSION
After the primary infection period, the VZV virus may stay latent in the spinal and cranial ganglia neurons and can subsequently get reactivated to cause Herpes zoster in later life. As it is a highly neurotropic virus, neurological complications are expected following either primary VZV infection or reactivation. Neurological complications of varicella in children are common but rare in adults but associated with increased morbidity. It can affect both immunocompetent and immunosuppressed individuals. VZV is the only human virus that has been proven to replicate in cerebral arteries and cause cerebral arterial vasculopathy resulting in infarcts. It is believed that there is trans axonal transport of varicella zoster virus from cervical or trigeminal afferent fibers to the cerebral blood vessels to the adventitia followed by transmural migration to the arterial media and intima. The mechanisms underlying cerebral vascular events after VZV infection could be thrombosis due to direct endothelial damage, inflammation, vascular wall remodeling and disruption of internal elastic lamina. 1 More recent studies have expanded the clinical spectrum of VZV vasculopathy to include aneurysms, dissection, ischemic cranial neuropathies, cerebral venous sinus thrombosis, and spinal cord infarction. The exact pathogenesis of varicella venous thrombosis is not known but similar to VZV arterial strokes. Activated varicella virus may migrate transaxonally to infect the meninges and venous sinuses of brain. Primary VZV infection can cause vascular thrombosis approximately 6weeks after primary infection. An acquired antibody-mediated hypercoagulable state resulting from decreased levels of natural anticoagulants like protein S in the viremic phase of the infection is also postulated to provoke thrombosis. [2][3][4] The latent period of 2-3weeks signifies the time for the direct venous endothelium damage or development of autoantibodies to natural anticoagulants leading to widespread thrombotic process.
Very few cases of venous sinus thrombosis have been reported in literature. [5][6][7][8] Our case developed CVST in the stage of primary infection itself. History of chickenpox, investigations and available literature helped confirm the diagnosis.
CONCLUSION
Cerebral venous sinus thrombosis (CVST) is a rare neurological complication associated with primary VZV infection. Early diagnosis and management can help prevent associated morbidity and mortality and lead to better outcome. The physician should have high index of suspicion for hypercoagulability in patients following varicella infection and institute appropriate therapy.
Figure 1 :
1Haemorrhagic infarcts with diffuse cerebral swelling secondary to thrombosis of superior sagittal sinus.
Update on varicella zoster virus vasculopathy. M A Nagel, D Gilden, Cur Infect Dis Rep. 166407Nagel MA, Gilden D. Update on varicella zoster virus vasculopathy. Cur Infect Dis Rep. 2014;16(6):407.
. M Gurinder, Int J Adv Med. 46Gurinder M et al. Int J Adv Med. 2017 Dec;4(6):1693-1695
. International Journal of Advances in Medicine. 61695International Journal of Advances in Medicine | November-December 2017 | Vol 4 | Issue 6 Page 1695
Lupus anticoagulant and protein S deficiency in otherwise healthy children with acute varicella infection. Z Kurugöl, F Vardar, F Özkinay, K Kavakh, C Özkinay, Acta Paediatrica. 8910Kurugöl Z, Vardar F, Özkinay F, Kavakh K, Özkinay C. Lupus anticoagulant and protein S deficiency in otherwise healthy children with acute varicella infection. Acta Paediatrica. 2000;89(10):1186-9.
Varicella and thrombotic complications associated with transient protein C and protein S deficiencies in children. P Nguyên, J Reynaud, P Pouzol, M Munzer, O Richard, P François, Eur J Pedi. 153Nguyên P, Reynaud J, Pouzol P, Munzer M, Richard O, François P. Varicella and thrombotic complications associated with transient protein C and protein S deficiencies in children. Eur J Pedi. 1994;153:646-9.
Cerebral venous sinus thrombosis (CVST) secondary to varicella induced hypercoagulable state in a adult. B Sudhaker, M P Dnyaneshwar, C R Jaidip, S M Rao, Internal Medicine Inside. 211Sudhaker B, Dnyaneshwar MP, Jaidip CR, Rao SM. Cerebral venous sinus thrombosis (CVST) secondary to varicella induced hypercoagulable state in a adult. Internal Medicine Inside. 2014;2(1):1.
Cerebral sinus venous thrombosis: A rare complication of primary Varicella zoster virus. S Sada, A Kammineni, M A Kanikannan, J Afshan, Neurol Ind. 60Sada S, Kammineni A, Kanikannan MA, Afshan J. Cerebral sinus venous thrombosis: A rare complication of primary Varicella zoster virus. Neurol Ind. 2012;60:645-6
Cerebral venous thrombosis as a complication of chicken pox. B Menon, R Goyal, Ann Trop Med Public Health. 5Menon B, Goyal R. Cerebral venous thrombosis as a complication of chicken pox. Ann Trop Med Public Health. 2012;5:520-2
Cerebral venous sinus thrombosis: association with primary varicella zoster virus infection. S A Siddiqi, S Nishat, D Kanwar, F Ali, Azeemuddin , M Wasay, M , J Stroke Cere Dis. 21917Siddiqi SA, Nishat S, Kanwar D, Ali F, Azeemuddin M and Wasay M. Cerebral venous sinus thrombosis: association with primary varicella zoster virus infection. J Stroke Cere Dis. 2012;21:917
Acute Venous Sinus Thrombosis after Chickenpox Infection. V Sardana, L C Mittal, S R Meena, D Sharma, G Khandelwal, JAPI. Sardana V, Mittal LC, Meena SR, Sharma D, Khandelwal G. Acute Venous Sinus Thrombosis after Chickenpox Infection. JAPI. 2014:81-3.
Sagittal Sinus Thrombosis Secondary to Varicella Infection-A Case Report. M Gurinder, H Kaur, N Kaur, Int J Adv Med. 4Cite this article asCite this article as: Gurinder M, Kaur H, Kaur N. Sagittal Sinus Thrombosis Secondary to Varicella Infection-A Case Report. Int J Adv Med 2017;4:1693-5.
| [
-0.14152544736862183,
-0.0003535440191626549,
-0.08591568470001221,
0.03918880224227905,
-0.08128610253334045,
0.14723354578018188,
-0.06227799504995346,
0.20935791730880737,
0.15513987839221954,
0.0694412887096405,
-0.03784927725791931,
0.06101379171013832,
0.05415470153093338,
0.18338403... |
Nabi N
April 2021. 1402. 2021 Apr. 2021 Apr. April 2021
Department of General Surgery
SKIMS Medical College Bemina
SrinagarJammu, KashmirIndia
Nabi N
International Surgery Journal Nabi N. Int Surg J
841403April 2021. 1402. 2021 Apr. 2021 Apr. April 202110.18203/2349-2902.isj20211333Received: 24 January 2021 Revised: 04 March 2021 Accepted: 05 March 2021Review Article *Correspondence: Dr. Naveed Nabi,GSDCholecystectomyRestrictive criteriaHistorical evolution of cholecystectomy
Gall stone disease (GSD) is one among the most common reasons for which patients flock the office of general surgeons and cholecystectomy is one of the most common surgeries performed worldwide. Though majority of the patients are asymptomatic but a considerable number among them are deprived of their vital gall bladder for just or unjust reasons. With the introduction of laparoscopic cholecystectomy, there has been significant escalation in unnecessary cholecystectomies leading to excessive burden on health care system as well as subjecting patients to undue surgical risk. Considering the benign natural history of GSD, a restrictive strategy should be adopted while deciding surgical management for GSD. In this article, the author has given evidence from already published literature to support his views. Preoperative and sincere assessment of each symptom with exclusion of functional disorders and due consideration of patient's life expectancy are paramount in reducing unnecessary cholecystectomies as well as ensuring long tern relief of symptoms post-surgery.
INTRODUCTION
Cholelithiasis contributes significantly to global healthcare burden and is the most prevalent medical abnormality in the pancreatobiliary system. 1,2 It is estimated that gall stones affect 10-15% of population in United States which constitutes around 25 million people. However, its prevalence varies among different populations ( Figure 1). Among American adults, the prevalence of gallstone disease is about 10% while in Western Europe, the prevalence ranges from 5.9 to 21.9%. In Asian countries, prevalence ranges from 3.2 to 15.6%. 3 Gallstone disease (GSD) is a leading cause for hospital admissions related to gastrointestinal problems. 4 In United States it has been estimated that 1.8 million ambulatory care visits each year are because of cholelithiasis. These numbers are likely an underestimate because laparoscopic cholecystectomy is often performed as a day-care procedure and thus not included in hospital statistics that require overnight admission. Cholecystectomy is one among the most common surgeries performed by general surgeons worldwide, hence, contributing substantially to overall health care costs. The direct and indirect cost of gallbladder disease represents a consumption of ~$6.2 billion annually in the U.S, with over 750,000 operations being performed annually. 5 The number of surgical procedures for cholelithiasis has risen markedly in developed countries since 1950. 6 The introduction of laparoscopic cholecystectomy in 1989 further increased the cholecystectomy rate. 6-8 From 1990 to 1993, there was a 28% escalation in the number of cholecystectomies performed. 9 The change in practice resulted from the laparoscopic surgical approach, which represented a less invasive, more cosmetically acceptable operation while providing a lower surgical risk compared to the then conventional or "open" procedure. This likely resulted in more surgeries being done in patients who were previously thought to be high risk, or in those who had minimal symptoms. With the adoption of laparoscopic approach, the speculation of inappropriate increase in the rate of cholecystectomies seems justifiable to the author of this article. A thorough literature review was done to support the above hypothesis and hence, give an insight into the need for strict definition of symptomatic cholelithiasis which happens to be absolute indication of Cholecystectomy and most common reason for which cholecystectomies are done.
HISTORICAL EVOLUTION IN SURGICAL MANAGEMENT OF GSD
The first note of gallstones was given in 1420 by a pathologist Antonio Benevieni, in a woman who died with abdominal pain. 10 However, there are reports of Gallstones being found in the gallbladders of Egyptian mummies dating back to 1000 B.C. 11 The first encounter of gallstones with a surgeon dates back to 1687 when Der Wiel, while operating a patient with purulent peritonitis accidentally found gallstones. 12 Jean-Louis Petit (founder of gall bladder surgery) in 1733, suggested that in a patient with cholelithiasis, gallstones should be removed followed by drainage of the gall bladder, thus creating a fistula, which he successfully performed in 1743. 12 In 1859 Thudichum proposed a twostage elective cholecystostomy. 13 In the first stage, the inflamed gall bladder was sewed to the anterior abdominal wall through a small incision, which served as a route for the removal of gall stone at a later date. At around the same time, in 1867, Dr John Stough Bobbs, did an incidental cholecystostomy while he was operating on a patient with suspected ovarian cyst. Theodor Kocher performed the first successful cholecystostomy in 1878. 13,14 It was Carl Johann August Langenbuch who observed that cholecystostomy was only a temporary measure and strived to find a definite management option for the disease. 14 At that time biliary colic was more a medical problem and ordinary surgeons were inadequately exposed to the problem. Langenbuch at the age of 27 developed the technique of cholecystectomy through cadaveric dissection and on July 15, 1882 he successfully removed the gall bladder of a 43-year-old man who was suffering from the disease for 16 years. His initial report appeared in 1882 but was ignored. This new cholecystectomy was debated against the already established cholecystostomy. Langenbuch died on June 9, 1901 of neglected appendicitis but the path showed by him led to further advancement and modification in biliary surgery.
Langenbuch's open cholecystectomy remained the gold standard for symptomatic cholelithiasis for over a century. The only major change was brought by Mirizzi which was the introduction of operative cholangiography for the detection of common bile duct stones. 15 Mouret from France performed the first human laparoscopic cholecystectomy. 16 He performed the procedure successfully and the patient recovered without complications. Finally, in September 1992 a NIH consensus conference held in Bethesda concluded that laparoscopic cholecystectomy was the treatment of choice for gall bladder lithiasis. 17
INDICATIONS OF CHOLECYSTECTOMY IN CHOLELITHIASIS
Majority of people with cholelithiasis will not develop symptoms: up to 80% will never experience biliary pain or complications such as acute cholecystitis, cholangitis, or pancreatitis. 18 Hence, most gallstones are clinically "silent," an incidental finding often revealed during abdominal ultrasound being performed for another reason. 19 People with such asymptomatic cholelithiasis, however, eventually may develop symptoms (biliary pain) but this risk is quite low averaging 2 to 3% per year, 10% by 5 years. 20,21 Even lower proportions, 1 to 2% per year, develop major gallstone complications. 22 Therefore, expectant management is an appropriate choice for silent gallstones in the general population.
However, there are some sub groups of patients who need prophylactic cholecystectomy even if asymptomatic: (1) Large gallstones (>3 cm) or gallbladders packed with stones that carry a higher risk of developing gallbladder cancer. 23 (2) Sickle cell disease is associated with the development of pigment gallstones, frequently necessitating cholecystectomy. Prophylactic cholecystectomy should be considered because stone related complications are frequently difficult to distinguish from a sickle cell crisis or its complications such as infarction of the liver or abdominal viscera. 24 (3) Solid organ transplantation (heart, lung, kidney, pancreas). Gallstones that develop post-solid organ transplantation frequently progress to symptoms and complications like cholecystitis, principally during the first 2 years. 25 Liver transplantation is exempted as the gallbladder is removed at the time of hepatectomy. (4) Morbidly obese patients undergoing bariatric surgery. 26 (5) Porcelain Gallbladder due to increased risk of malignancy. (6) Dysmotile Gallbladder laden with small stones, as has increased risk of pancreatitis. 27 (7) Native Americans because they have higher risk of gallbladder cancer than general population.
Symptomatic GSD causing biliary colic has always remained an uncontroversial and most common indication for cholecystectomy. Though, it is also the only indication which requires thorough deliberation and exclusions to accurately label the symptoms as being gall stone induced.
NEED TO ADOPT RESTRICTIVE CRITERIA FOR ELECTIVE CHOLECYSTECTOMIES
It is essential to define exactly which symptoms are caused by gallstones: true biliary pain and/or complications, versus nonspecific abdominal complaints including dyspepsia. [28][29][30] Gallstone-associated pain seems to follow a certain pattern in most patients. 31,32 Consensus groups have attempted to establish criteria for biliary pain relative to defined characteristics (e.g., episodic, steady, severe pain located in the upper abdomen and lasting more than 30 minutes) and some accompanying features (e.g., nocturnal onset; nausea and vomiting; radiating through to the back). 33 The importance for clarifying what constitutes true biliary pain is to better predict relief following cholecystectomy.
The accurate diagnosis of true biliary pain is also pivotal in bringing down the rate of unnecessary cholecystectomies as well as preventing a significant proportion of patients from undue surgical risk and health care cost. Currently, cholecystectomy does not relieve biliary pain in 10 to 33% of people with documented gallstones. 34,35 Confusion with other functional gut disorders like irritable bowel syndrome (IBS) and dyspepsia will not provide a favourable outcome from cholecystectomy. 36 Mertens et al conducted a prospective study to identify the predictors of persisting symptoms postcholecystectomy. 36 At 6 months after cholecystectomy, merely 47.8% of the patients were symptom free. In addition, 17.9 and 34.0% of the patients reported persistence and emergence of new symptoms, respectively. Hence, it becomes pertinent to mention that preoperative recognition of patients with an increased risk of negative outcome is essential to optimise the management of cholelithiasis. The study also demonstrated that patients with preoperative dyspeptic symptoms only and patients using psychotropic medication are both at risk of persistence of the preexisting pattern of health complaints after cholecystectomy.
Thistle et al followed their study patients for 12 months post-cholecystectomy to determine the preoperative predictors associated with sustained post-operative relief with respect to upper abdominal pain (UAP). 59% of the patients reported sustained relief from UAP. 37 Factors associated with relief included frequency of UAP ≤1 episode per month, onset ≤1 year preoperatively, usual duration (30 minutes to 24 hours, most often in the evening or night), and severity >5/10. Association of UAP with GERD, IBS like symptoms or somatisation determine the odds for relief of symptoms after cholecystectomy.
A Swedish surgeon Persson conducted a prospective study on expectant management of GSD and followed the study patients for 6 years. 38 After the completion of 6year follow up only 23 (15%) patients developed acute gall stone related complication, acute cholecystitis (n=18), acute pancreatitis (n=2), and jaundice (n=3). The overall cholecystectomy rate fell from 20 % during the 1 st year to about 3% during the 5 th year of follow-up. Young age and frequent attacks of true biliary pain episodes predicted the need for gallstone surgery.
Festi et al conducted a multi-centre, population-based cohort study on 11229 subjects. Gall stone patients were followed up for a mean period of 8.7 years. At the end of the follow up, of the asymptomatic subjects, 453 (78.1%) remained asymptomatic; 61 (10.5%) developed mild symptoms and 66 (11.4%) developed severe symptoms. 39 In subjects with mild symptoms, the symptoms disappeared in 55 (58.5%), became severe in 23 (24.5%), remained stable in 16 (17%); in subjects with severe symptoms, the symptoms disappeared in 62 (52.1%), became mild in 20 (16.8%) and remained stable in 37 (31.1%). A total of 189 cholecystectomies were performed: 41.3% on asymptomatic patients, 17.4% on patients with mild symptoms and 41.3% on patients with severe symptoms.
The lancet writes that adopting restrictive selection criteria for decision making significantly reduces the rates of unnecessary cholecystectomies (68% as compared to 75% in usual care group) than operating merely on surgeon's discretion. 40
DISCUSSION
In this review of literature, significant numbers of studies suggest that cholecystectomy should be a well thought out decision based on predictors of symptom relief, not merely on surgeon's discretion. Though laparoscopic cholecystectomy revolutionised the management of GSD, however, it was accompanied by significantly lowered threshold for cholecystectomies, resulting in escalation of cholecystectomy rates of the order of 22% reported in some studies. 41 However, the considerable reduction in post-operative morbidity after laparoscopic cholecystectomy must also be appreciated.
The association of true biliary pain with gall stones is paramount in predicting success following a cholecystectomy. Coexistent diseases in patients with cholelithiasis are common and mainly non-biliary like gastro-oesophageal reflux, peptic ulcer, hiatus hernia, gastritis, constipation, IBS, fatty liver disease. Distinction between symptoms caused by coexistent diseases and gallstones is challenging. 42 Misinterpretation of symptoms and suboptimal indication for laparoscopic cholecystectomy will result in persistent symptoms after surgery. 43,44 CONCLUSION Laparoscopic cholecystectomy remains the gold standard for treatment of symptomatic gall stone disease. However, it is equally important to mention that avoidance of an unnecessary cholecystectomy becomes critically germane in an era of escalating rates of surgery. Jumping to a cholecystectomy may not always yield good outcomes, although many do still benefit from having a cholecystectomy. There is a need to rigidly define symptomatic cholelithiasis and true biliary pain based on fixed restrictive criteria in order to bring down the rates of unnecessary cholecystectomies and hence, lessen the burden on health care institutions. This will also pave the way for saving considerable amount of health care cost. Besides, it must be insisted that a shared decision making will impart a better understanding to the patient about negative outcomes after a non-essential cholecystectomy.
Hopefully further studies will give an insight to what might cause symptoms and when a cholecystectomy is likely to relieve symptoms.
Funding: No funding sources Conflict of interest: None declared Ethical approval: Not required
Figure 1 :
1Worldwide prevalence of gallstones in females based on ultrasonographic surveys.45
Cite this article as: Nabi N. Need for restrictive criteria to define symptomatic cholelithiasis to avoid unnecessary cholecystectomies-evidence from the literature review. Int Surg J 2021;8:1402-6.
Changes in demographic features of gallstone disease: 30 years of surgically treated patients. Y R Chang, J Y Jang, W Kwon, J W Park, M J Kang, J K Ryu, Gut and Liver. 76Chang YR, Jang JY, Kwon W, Park JW, Kang MJ, Ryu JK et al. Changes in demographic features of gallstone disease: 30 years of surgically treated patients. Gut and Liver. 2013;7(6):719-24.
Cholesterol gallstone disease. P Portincasa, A Moschetta, G Palasciano, Lancet. 3689531Portincasa P, Moschetta A, Palasciano G. Cholesterol gallstone disease. Lancet (London, England). 2006;368(9531):230-9.
Epidemiology and risk factors for gallstone disease: has the paradigm changed in the 21st century?. E A Shaffer, Current Gastroenterol Rep. 72Shaffer EA. Epidemiology and risk factors for gallstone disease: has the paradigm changed in the 21st century? Current Gastroenterol Rep. 2005;7(2):132-40.
The burden of gastrointestinal and liver diseases. N J Shaheen, R A Hansen, D R Morgan, Am J Gastroenterol. 101Shaheen NJ, Hansen RA, Morgan DR. The burden of gastrointestinal and liver diseases. Am J Gastroenterol. 2006;101:2128-38.
Prevalence and ethnic differences in gallbladder disease in the United States. J E Everhart, M Khare, M Hill, K R Maurer, Gastroenterology. 117Everhart JE, Khare M, Hill M, Maurer KR. Prevalence and ethnic differences in gallbladder disease in the United States. Gastroenterology. 1999;117:632-9.
Increased cholecystectomy rate after the introduction of laparoscopic cholecystectomy. A P Legorreta, J H Silber, G N Costantino, R W Kobylinski, S L Zatz, JAMA. 270Legorreta AP, Silber JH, Costantino GN, Kobylinski RW, Zatz SL. Increased cholecystectomy rate after the introduction of laparoscopic cholecystectomy. JAMA. 1993;270:1429-32.
The impact of laparoscopic cholecystectomy in Canada and Australia. D Marshall, E Clark, D Hailey, Health Policy. 26Marshall D, Clark E, Hailey D. The impact of laparoscopic cholecystectomy in Canada and Australia. Health Policy. 1994; 26:221-30.
Gallstones: an increasing problem: a study of hospital admissions in England between 1989/1990 and 1999/2000. J Y Kang, C Ellis, A Majeed, Aliment Pharmacol Ther. 17Kang JY, Ellis C, Majeed A. Gallstones: an increasing problem: a study of hospital admissions in England between 1989/1990 and 1999/2000. Aliment Pharmacol Ther. 2003;17:561-9.
Increased cholecystectomy rates among Medicare patients after the introduction of laparoscopic cholecystectomy. R P Nenner, P J Imperato, C Rosenberg, E Ronberg, J Community Health. 19Nenner RP, Imperato PJ, Rosenberg C, Ronberg E. Increased cholecystectomy rates among Medicare patients after the introduction of laparoscopic cholecystectomy. J Community Health. 1994;19:409-15.
The biliary system through the ages. W H Shehadi, Int Surg. 6463Shehadi WH. The biliary system through the ages. Int Surg. 1979;64:63.
Anatomy of gallstones. N A Womack, R Zeppa, G L Irvin, Ann Surg. 157670Womack NA, Zeppa R, Irvin GL. Anatomy of gallstones. Ann Surg. 1963;157:670.
Historical perspective of gall stone disease. J M Beal, Surg Gynecol Obstet. 15881Beal JM. Historical perspective of gall stone disease. Surg Gynecol Obstet. 1984;158:81.
Leading surgical procedures. Stat Bull Metropol Life Ins Co. 5410Leading surgical procedures. Stat Bull Metropol Life Ins Co. 1973;54:10.
Christianismi Restitutio and Other Writings. Birmingham. The Classics of Medicine Library. M ( Servetus, C D O'malley, 115Servetus M. (O'Malley CD, trans). Christianismi Restitutio and Other Writings. Birmingham. The Classics of Medicine Library. 1989:115.
Operative cholangiography. P L Mirizzi, Lancet. 2Mirizzi PL. Operative cholangiography. Lancet. 1938;2:366-9.
from the first laparoscopic cholecystectomy to the frontiers of laparoscopic surgery: the prospective futures. P Mouret, Dig Surg. 8124Mouret P. from the first laparoscopic cholecystectomy to the frontiers of laparoscopic surgery: the prospective futures. Dig Surg. 1991;8:124.
NIH Consensus Conference: Gallstones and laparoscopic cholecystectomy. 269NIH Consensus Conference: Gallstones and laparoscopic cholecystectomy. JAMA. 1993;269:1018-24.
Asymptomatic cholelithiasis: is cholecystectomy really needed? A critical reappraisal 15 years after the introduction of laparoscopic cholecystectomy. G H Sakorafas, D Milingos, G Peros, Dig Dis Sci. 52Sakorafas GH, Milingos D, Peros G. Asymptomatic cholelithiasis: is cholecystectomy really needed? A critical reappraisal 15 years after the introduction of laparoscopic cholecystectomy. Dig Dis Sci. 2007;52:1313-25.
Development of symptoms and complications in individuals with asymptomatic gallstones. I Halldestam, E L Enell, E Kullman, K Borch, Br J Surg. 91Halldestam I, Enell EL, Kullman E, Borch K. Development of symptoms and complications in individuals with asymptomatic gallstones. Br J Surg. 2004;91:734-8.
The natural history of cholelithiasis: The National Cooperative Gallstone Study. J L Thistle, P A Cleary, J M Lachin, M P Tyor, T Hersh, Ann Intern Med. 101Thistle JL, Cleary PA, Lachin JM, Tyor MP, Hersh T. The natural history of cholelithiasis: The National Cooperative Gallstone Study. Ann Intern Med. 1984;101:171-5.
Prophylactic cholecystectomy or expectant management for silent gallstones. A decision analysis to assess survival. D F Ransohoff, W A Gracie, L B Wolfenson, D Neuhauser, Ann Intern Med. 99Ransohoff DF, Gracie WA, Wolfenson LB, Neuhauser D. Prophylactic cholecystectomy or expectant management for silent gallstones. A decision analysis to assess survival. Ann Intern Med. 1983;99:199-204.
Natural history of asymptomatic and symptomatic gallstones. G D Friedman, Am J Surg. 165Friedman GD. Natural history of asymptomatic and symptomatic gallstones. Am J Surg. 1993;165:399-404.
Cholecystectomy in patients with asymptomatic gallstones to prevent gall bladder cancer: the case against. V K Kapoor, Indian J Gastroenterol. 25Kapoor VK. Cholecystectomy in patients with asymptomatic gallstones to prevent gall bladder cancer: the case against. Indian J Gastroenterol. 2006;25:152-4.
Laparoscopic cholecystectomy in adults with sickle cell disease. G Bonatsos, K Birbas, K Toutouzas, N Durakis, Surg Endosc. 15Bonatsos G, Birbas K, Toutouzas K, Durakis N. Laparoscopic cholecystectomy in adults with sickle cell disease. Surg Endosc. 2001;15:816-9.
Should cholecystectomy be performed for asymptomatic cholelithiasis in transplant patients?. L S Kao, C S Kuhr, D R Flum, J Am Coll Surg. 197Kao LS, Kuhr CS, Flum DR. Should cholecystectomy be performed for asymptomatic cholelithiasis in transplant patients? J Am Coll Surg. 2003;197:302-2.
Gallstone formation after rapid weight loss: a prospective study in patients undergoing gastric bypass surgery for treatment of morbid obesity. M L Shiffman, H J Sugerman, J M Kellum, W H Brewer, E W Moore, Am J Gastroenterol. 86Shiffman ML, Sugerman HJ, Kellum JM, Brewer WH, Moore EW. Gallstone formation after rapid weight loss: a prospective study in patients undergoing gastric bypass surgery for treatment of morbid obesity. Am J Gastroenterol. 1991;86:1000-5.
Small gallstones, preserved gallbladder motility, and fast crystallization are associated with pancreatitis. N G Venneman, W Renooij, J F Rehfeld, Hepatology. 414Venneman NG, Renooij W, Rehfeld JF. Small gallstones, preserved gallbladder motility, and fast crystallization are associated with pancreatitis. Hepatology. 2005;41(4):738-46.
Abdominal symptoms and gallstone disease: an epidemiological investigation. T Jørgensen, Jørgensen T. Abdominal symptoms and gallstone disease: an epidemiological investigation.
. Hepatology. 9Hepatology. 1989; 9:856-60.
Clinical manifestations and impact of gallstone disease. L W Traverso, Am J Surg. 165Traverso LW. Clinical manifestations and impact of gallstone disease. Am J Surg. 1993;165:405-9.
What symptoms does cholecystectomy cure? Insights from an outcomes measurement project and review of the literature. L F Fenster, R Lonborg, R C Thirlby, L W Traverso, Am J Surg. 169Fenster LF, Lonborg R, Thirlby RC, Traverso LW. What symptoms does cholecystectomy cure? Insights from an outcomes measurement project and review of the literature. Am J Surg. 1995;169:533-8.
Clinical manifestations of gallstone disease: evidence from the multicenter Italian study on cholelithiasis (MICOL). D Festi, S Sottili, A Colecchia, Hepatology. 30Festi D, Sottili S, Colecchia A. Clinical manifestations of gallstone disease: evidence from the multicenter Italian study on cholelithiasis (MICOL). Hepatology. 1999;30:839-46.
Pain attacks in non-complicated and complicated gallstone disease have a characteristic pattern and are accompanied by dyspepsia in most patients: the results of a prospective study. T Berhane, M Vetrhus, T Hausken, S Olafsson, K Søndenaa, Scand J Gastroenterol. 41Berhane T, Vetrhus M, Hausken T, Olafsson S, Søndenaa K. Pain attacks in non-complicated and complicated gallstone disease have a characteristic pattern and are accompanied by dyspepsia in most patients: the results of a prospective study. Scand J Gastroenterol. 2006;41:93-101.
Gallstone disease is associated with increased mortality in the United States. C E Ruhl, J E Everhart, Gastroenterology. 140Ruhl CE, Everhart JE. Gallstone disease is associated with increased mortality in the United States. Gastroenterology. 2011;140:508-16.
Relationship between persistence of abdominal symptoms and successful outcome after cholecystectomy. C R Weinert, D Arnett, D JacobsJr, R L Kane, Arch Intern Med. 160Weinert CR, Arnett D, Jacobs D Jr, Kane RL. Relationship between persistence of abdominal symptoms and successful outcome after cholecystectomy. Arch Intern Med. 2000;160:989-95.
Pain persists in many patients five years after removal of the gallbladder: observations from two randomized controlled trials of symptomatic, non-complicated gallstone disease and acute cholecystitis. M Vetrhus, T Berhane, O Søreide, K Søndenaa, J Gastrointest Surg. 9Vetrhus M, Berhane T, Søreide O, Søndenaa K. Pain persists in many patients five years after removal of the gallbladder: observations from two randomized controlled trials of symptomatic, non-complicated gallstone disease and acute cholecystitis. J Gastrointest Surg. 2005;9:826-31.
Risk assessment in cholelithiasis: is cholecystectomy always to be preferred?. M C Mertens, J A Roukema, V P Scholtes, De Vries, J , J Gastrointest Surg. 14Mertens MC, Roukema JA, Scholtes VP, De Vries J. Risk assessment in cholelithiasis: is cholecystectomy always to be preferred? J Gastrointest Surg. 2010;14:1271-9.
Factors that predict relief from upper abdominal pain after cholecystectomy. J L Thistle, G F Longstreth, Y Romero, A S Arora, J A Simonson, N N Diehl, Clin Gastroenterol Hepatol. 910Thistle JL, Longstreth GF, Romero Y, Arora AS, Simonson JA, Diehl NN et al. Factors that predict relief from upper abdominal pain after cholecystectomy. Clin Gastroenterol Hepatol. 2011;9(10):891-6.
Expectant management of patients with gallbladder stones diagnosed at planned investigation. A prospective 5-to 7-year follow-up study of 153 patients. G E Persson, Scand J Gastroenterol. 312Persson GE. Expectant management of patients with gallbladder stones diagnosed at planned investigation. A prospective 5-to 7-year follow-up study of 153 patients. Scand J Gastroenterol. 1996;31(2):191-9.
Natural history of gallstone disease: Expectant management or active treatment? Results from a population-based cohort study. D Festi, M L Reggiani, A F Attili, P Loria, P Pazzi, E Scaioli, J Gastroenterol Hepatol. 254Festi D, Reggiani ML, Attili AF, Loria P, Pazzi P, Scaioli E et al. Natural history of gallstone disease: Expectant management or active treatment? Results from a population-based cohort study. J Gastroenterol Hepatol. 2010;25(4):719-24.
Restrictive strategy versus usual care for cholecystectomy in patients with gallstones and abdominal pain (SECURE): a multicentre, randomised, parallel-arm, non-inferiority trial. A H Van Dijk, S Z Wennmacker, P R De Reuver, Css Latenstein, O Buyne, S C Donkervoort, The Lancet. 393van Dijk AH, Wennmacker SZ, de Reuver PR, Latenstein CSS, Buyne O, Donkervoort SC, et al. Restrictive strategy versus usual care for cholecystectomy in patients with gallstones and abdominal pain (SECURE): a multicentre, randomised, parallel-arm, non-inferiority trial. The Lancet. 2019;393(101388):2322-30.
Falling cholecystectomy thresholds since the introduction of laparoscopic cholecystectomy. J J Escarce, W Chen, J S Schwartz, JAMA. 27320Escarce JJ, Chen W, Schwartz JS. Falling cholecystectomy thresholds since the introduction of laparoscopic cholecystectomy. JAMA. 1995;273(20):1581-5.
Gastrointestinal qualityof-life after cholecystectomy: indication predicts gastrointestinal symptoms and abdominal pain. V Wanjura, P Lundstrom, J Osterberg, I Rasmussen, B M Karlson, G Sandblom, World J Surg. 3812Wanjura V, Lundstrom P, Osterberg J, Rasmussen I, Karlson BM, Sandblom G. Gastrointestinal quality- of-life after cholecystectomy: indication predicts gastrointestinal symptoms and abdominal pain. World J Surg. 2014;38(12):3075-81.
Health-related quality of life outcomes after cholecystectomy. A Carraro, D El Mazloum, F Bihl, World J Gastroenterol. 1745Carraro A, El Mazloum D, Bihl F. Health-related quality of life outcomes after cholecystectomy. World J Gastroenterol. 2011;17(45):4945-1.
Abdominal symptoms: do they disappear after cholecystectomy?. M Y Berger, Olde Hartman, T C Bohnen, A M , Surgical Endoscopy. 1711Berger MY, Olde Hartman TC, Bohnen AM. Abdominal symptoms: do they disappear after cholecystectomy? Surgical Endoscopy. 2003;17(11):1723-8.
Epidemiology of Gallbladder Disease: Cholelithiasis and Cancer. L M Stinton, E A Shaffer, Gut Liver. 6Stinton LM, Shaffer EA. Epidemiology of Gallbladder Disease: Cholelithiasis and Cancer. Gut Liver. 2012;6:172-87.
| [
0.047590404748916626,
-0.08657826483249664,
0.06867579370737076,
0.07189641147851944,
-0.2633723020553589,
-0.05531321465969086,
-0.04690536856651306,
0.05530788376927376,
0.004842989146709442,
-0.08893579989671707,
-0.012404011562466621,
0.07222577929496765,
0.06541760265827179,
0.0321873... |
Safety Assessment of Driving Support Functions as Human-machine System
ksuzuki@eng.kagawa-u.acKeisuke Suzuki
Department of Intelligent Mechanical Systems Engineering
Kagawa University
2217-20Hayashi, Takamatsu city
Takuya Namera
Department of Intelligent Mechanical Systems Engineering
Kagawa University
2217-20Hayashi, Takamatsu city
Safety Assessment of Driving Support Functions as Human-machine System
Safety Impact AssessmentDriving SupportDriving SimulatorESK-JES Joint Session
We propose an evaluation methodology to analyze the safety level of advanced driver assistance systems (ADAS) as a humanmachine system in terms of comparing the increase in the safety level during normal system operation and the decrease in the safety level during a system malfunction. We propose a concept of combined error for the human-machine system and quantify this combined error by driving simulator investigations and simulation studies. First, we investigated the drivers' behavior when avoiding rear-end collisions with a preceding vehicle when equipped with ADASs-like ACC and LKA or FCW and LDW. Then, we confirmed that the risk of collision induced by overdependence on the systems was not increased when the ADASs were mounted on the vehicle using simulation studies based on the concept of combined error for the human-machine system. We also confirmed that the decrease in collisions when the ADASs operated appropriately was much larger than the increase in collisions during a system malfunction.
Introduction
A trade-off analysis between the positive effects, i.e., the decrease in the risk of collision with the system when it is operating normally, and the negative effects, i.e., the increase in the risk induced by an overdependence on the system when it is difficult to operate, is performed, and an example of the analysis is described in this study. Specifically, we analyzed changes in the risk of a collision of a vehicle equipped with ADAS. Two approaches were adopted and combined in the analysis: one was an experiment with a driving simulator and the other was a time-series simulation of the reliability of ADAS and the driver, wherein they were modeled as a human-machine system.
Collision Mitigation Effectiveness Quantification Methodology
To quantify the collision mitigation effectiveness when a vehicle is equipped with the system, a situation wherein it is difficult for the system to be operational should be considered in the analysis in addition that wherein ADAS is operating normally. The former situation could occur for any reason despite the probability of such an occurrence being small. Suzuki et al. (2011) proposed a concept to estimate a driver's error when a vehicle is equipped with the system. In this concept, the reliability of the system and driver are combined, assuming that the occurrence of a situation wherein it is difficult for the system to be normally operated (hereinafter referred to as the "system error") and that wherein the driver cannot control the vehicle normally (hereinafter referred to as the "driver error") are independent. The vertical axis of Figure 1 indicates system reliability, i.e., the system's possibility of providing a driver with support, and the horizontal axis indicates the driver's reliability, i.e., the driver's possibility of driving the vehicle normally. The zones surrounded by these axes express the overall reliability. In other words, zone A in Figure 1 expresses the possible decrease in the risk of collision when the system is normally operational, and zone B expresses the possible increase in risk when it is difficult for the system to operate. In zone B, there is a fear that the risk of collision could increase due to the driver's dependence on the system. When the area of zone A is larger than that of zone B, the collision probability of the vehicle equipped with the system is lower than that of a vehicle not equipped with the system, implying that there are benefits when the system is applied in practice. Note that the reversed L-shaped zone in Figure 1 (the "total error") indicates the error probability of a vehicle controlled by a driver and system (or the combined collision probability of a vehicle equipped with the system).
In this analysis, the driving simulator test (driving test with a simulator, Figure 2) and simulations have been combined to determine whether the increase in collision probability is distinguishable when a vehicle is equipped with ACC and LKA. The area ratio between zones A and B is also discussed. Monte Carlo simulation was applied to estimate driver and system reliabilities.
Estimation of the Collision Risk
The collision probability of the normal state and that of the error state were sorted and are shown in Figure 3 and Figure 4. The collision probability is 40.3% when the system is not used under this condition, and the probability is reduced to as low as 1.16% when ACC is used. The decrease in the collision probability with the use of a system equivalent to zone A is 39.7%, and the probability increase with the use of a system equivalent to zone B is 0.557%.
Left; When the vehicle is not equipped with ADAS Right; When the vehicle is equipped with ACC Figure.3 Safety impact of ACC in decreasing collision probability
When a system is not used, the collision probability is 40.3%, whereas it is lowered to 1.11% when ACC and LKA are used. The collision probability decrease with the use of a system equivalent to zone A is 39.7%, and the probability increase with the use of a system equivalent to zone B is 0.457%. The driving simulator experiment and the simulation analysis reported herein indicate that the positive effect of the addition of LKA to ACC is slightly larger than the positive effect of one system only (ACC).
Figure. 4 Safety impact ADASs in decreasing collision
probability when LKA is installed in a vehicle equipped with ACC (LKA +ACC)
Conclusion
In the driver simulator experiment, when a vehicle was equipped with the combined ACC and LKA systems, drivers tended to focus on the subtask (operation of tablet PC) more than if they were driving a vehicle equipped with either ACC or LKA. However, it was confirmed that the probability of a rear-end collision with the leading vehicle did not vary. When these two functions were combined, the level of the driving load mitigation was enhanced. Drivers tended to divert their attention to other tasks while driving; however, they could still take appropriate actions against risks such as rear-end collisions.
In both cases, when a vehicle was equipped only with ACC or with both AAC and LKA, the decrease in the collision probability for the condition where the system can assist the driver, i.e., the system's normal state, was confirmed to be much higher than the increase in collision probability when it was difficult for the system to assist the driver, i.e., system error state. This was confirmed by the simulation analysis that used the driver behavior database obtained by the driving simulator experiment.
This study was carried out as a part of 5th ASV promotion project by Engineering Policy Division, Road Transport Bureau, Ministry of Land, Infrastructure, Transport and Tourism.
Figure 1 .Figure 2 .
12Combined error model to estimate driver and system reliabilities Experimental scenario in the driving simulator to simulate a rear-end collision
Method for Evaluating Effectiveness of Information Presentation in Terms of Collision Avoidance. K Suzuki, K Yamada, 1348-8503International Journal of Intelligent Transportation Systems Research. 91Suzuki, K. and Yamada, K. : "Method for Evaluating Effectiveness of Information Presentation in Terms of Collision Avoidance", International Journal of Intelligent Transportation Systems Research, ISSN 1348-8503, Vol.9, No. 1, p.37-46, 2011
| [
-0.04836980253458023,
0.001466466928832233,
-0.025038305670022964,
0.016665328294038773,
-0.03150910884141922,
-0.07651786506175995,
0.10948126018047333,
0.2862895727157593,
-0.04265111684799194,
0.1259530782699585,
0.12007419764995575,
-0.00020828284323215485,
0.16105283796787262,
-0.0090... |
Cryopreservation of Buffalo Bull Semen-Restriction and Expectation: A Review
2019
Pavan Kumar Mittal
Department of Veterinary Physiology and Biochemistry
A K Madan
Department of Veterinary Physiology
College of Veterinary and Animal Sciences
DUVASU
Mathura-281001India
Vijay Sharma
Department of Veterinary Public Health and Epidemiology
Post Graduate Institute of Veterinary Education and Research
Rajasthan-302031JaipurIndia
G S Gottam
Department of Veterinary Physiology and Biochemistry
Barkha Gupta
Department of Veterinary Physiology and Biochemistry
Cryopreservation of Buffalo Bull Semen-Restriction and Expectation: A Review
Int.J.Curr.Microbiol.App.Sci
81201910.20546/ijcmas.2019.801.1441351 Review Article *Corresponding author A B S T R A C T
Introduction
The world buffalo population is appraised at 185.29 million, spread in some 42 countries, of which 179.75 million (97%) are in Asia (Buffalopedia, 2015, www.buffalopedia. cirb.res.in). India has 108.7 millions and they comprise approximately 56.7% of the total world buffalo population (DAHDF, Govt. of India, 2015). Buffalo, a triple purpose animal, provides milk, meat and mechanical power to mankind. Due to its highly nutritious milk, leaner meat and best draught power for wet environments, buffalo offers immense potential for improvement of livelihood. Buffalo can efficiently convert low quality feed stuffs like straws and agro-industrial waste into human food, improve soil structure
International Journal of Current Microbiology and Applied Sciences
ISSN: 2319-7706 Volume 8 Number 01 (2019)
Journal homepage: http://www.ijcmas.com Semen cryopreservation is a widely used technique across the world for conservation and proliferation of genetically superior germplasm through artificial insemination. Artificial insemination (AI) is the most conclusive tool to increase genetic improvement, control of venereal diseases and improve herd performance and productivity. For achieving the mission, successful and effective cryopreservation of semen is essential. In recent years, increased demand of animal products due to very rapid growth of human population inspired the investigators to increase per animal milk production using various techniques of Biotechnology. The process of semen cryopreservation is stressful and around 40%-50% of sperm lose their motility and viability due to loss of structural and functional capabilities. One of the factors which affect post thaw survival of sperm is the freezing rate. In buffalo, poor fertility rate with cryopreserved semen is main obstacle in its proliferation. It is need of the time to spread the knowledge of various factors and components such as use of suitable extenders, additives, cryoprotectants, freezing and thawing protocols contributing in cryopreservation of semen to improve the fertility rate of buffalo.
through bio fertilizer and a financial asset which can be sold when needs arise (Pasha et al., 2012).
The genetic improvement and disease control in domestic animals have primary importance in the success of agriculture and food industry. In this contribution, artificial insemination (AI) is perhaps the most conclusive tool for modern ways of breed improvement. Moreover, the quality of frozen-thawed semen is one of the most influential factors affecting the likelihood of conception (Saacke, 1984). Application of AI with frozen-thawed semen has been reported on a limited scale in buffalo, because of poor freezability and fertility of buffalo spermatozoa when compared with cattle spermatozoa (Kakar and Anand, 1981;Muer et al., 1988;Raizada et al., 1990;Singh and Pant 2000;Andrabi et al., 2001Andrabi et al., , 2008Ahmad et al., 2003;Senatore et al., 2004;Kumaresan et al., 2005). In this process, each ejaculate collected from genetically superior male is used to inseminate females at a large scale and also controls sexually transmitted diseases.
Cryopreservation of spermatozoa
Cryopreservation is a non-physiological and complex method that involves a high level of adaptation of biological cells to the thermal and osmotic shocks that occur both during the dilution, cooling-freezing and during the thawing procedures (Watson et al., 1992;Holt 2000a, b). Damage occurring during the freezing-thawing procedures affects mainly cellular membranes and nucleus (Blesbois 2007) and affects finally viability and fertility. The cryopreservation development protocols in dairy industry started in 1950s. Semen cryopreservation is a composite process which involves many stages: extension (dilution), cooling, freeing, storage and thawing. During each stages, sperm structure and function are affected (Bailey et al., 2003) resulting in reduced sperm motility (Tuli et al., 1981), acrosomal damage and alteration in sperm membrane integrity (Rasul et al., 2001). Sperm Cryopreservation exposes sperm to mechanical and anisosmotic stresses (Hammerstedt et al., 1990) that reduces cell survival and surviving sperm, thereby reducing cell longevity and fertility compared with fresh semen.
Cryopreservation generates sublethal sperm injury due to chemical, osmotic, thermal and mechanical stresses, which may result in loss of viability, motility, damage of deoxyribonucleic acid (DNA), destruction of acrosomal and plasma membrane (Numan Bucak et al., 2007;Rasul et al., 2001). Furthermore, changes in biochemical factors have been recognized during cryopreservation, including depletion of amino acids and lipoproteins, release of glutamic-oxaloacetic transaminase (GOT), decrease in phosphatase activity, decrease in loosely bound cholesterol, protein, inactivation of acrosin enzyme and hyaluronidase, prostaglandins diminution, increase in sodium, decrease in potassium content, reduction of ATP and ADP synthesis and decrease in acrosomal proteolytic activity (Barbas et al., 2009). In fact sperm plasma membrane is a primary target for freezing or cold shock injury (Numan Bucak et al., 2009). The extender used is an important factor in cryopreservation process. These mediums must have adequate pH and buffering capacity, appropriate osmolality and should protect spermatozoa from cryogenic lesion. Tris extender is an important medium that is often used during freezing of bulls, rams, bucks and buffaloes semen (Barbas et al., 2009;Rasul et al., 2001).
The production of Reactive Oxygen Species (ROS) is a normal physiological event in various organs. However, the over-production of ROS can cause structural damage of sperm membranes (De Lamirande et al., 1997). Reactive oxygen is responsible for sperm dysfunction due the lipid peroxidation of membranes (Arabi et al., 2008). It has been documented that vitamin E is major antioxidant agent of sperm cells which is a potent scavenger of free radicals and is able to protect plasma membrane from damages mediated by ROS (Reactive Oxygen Species) and LPO (Lipid Peroxidation) (Yousef et al., 2003;Gurel et al., 2005 andSinclair, 2000). It has also been established that presence of vitamin E is necessary for normal function of male reproductive system. Sperm viability is depressed by as much as 50% during freezing (Watson 1995). To counteract destructive effects of ROS, seminal plasma has an antioxidant system that seems to be very relevant to protection of sperm (Alvarez and Storey, 1982). Furthermore, due to dilution of semen, antioxidant reserves of seminal plasma are depressed making spermatozoa more vulnerable to cryo insults. Therefore, it becomes all the more essential to incorporate anti-oxidants to semen extenders as protective agents. Assessing the structural and functional integrity of sperm membrane is of paramount importance in order to maintain optimum fertility potential of spermatozoa.
Cryodamage during freeze-thawing process to buffalo semen is higher than cattle spermatozoa due to unique physiology of buffalo spermatozoa and higher polyunsaturated phospholipids levels in plasma membrane (Nair et al., 2006;Sreejith et al., 2006;Andrabi, 2009). The fertility with frozen semen in buffaloes under field conditions is very poor and has been considered as 30% (Abhi, 1982;Chohan et al., 1992;Anzar et al., 2003;Andrabi, 2009). The reason for poor fertility rate in buffaloes under field conditions is poor post-thaw characteristics of buffalo semen. As a matter of fact, the unique physiology of buffalo sperm requires buffalo specific semen extender to reduce the cryodamages. Improving the semen extender for the cryopreservation that ensures no or little damage to sperm motility, plasmalemma, acrosomal and chromatin integrity might enable to achieve a comparatively higher fertility rate with artificial insemination in buffalo under field conditions. It is well documented that motility, plasma membrane, acrosome and DNA integrity of buffalo bull spermatozoa significantly reduced after process of cryopreservation (Rasul et al., 2001;Kadirvel et al., 2009;Anzar et al., 2010;Kumar et al., 2011). Cryopreservation of buffalo semen increases level of reactive oxygen species molecules that caused lipid peroxidation of biomembrane system by reducing antioxidant potential of cryopreserved semen (Kadirvel et al., 2009;Kumar et al., 2011).
To control level of ROS and promote motility and survival of sperm, numerous antioxidants have proven beneficial in treating male infertility (Sinclair, 2000). Ascorbic acid and vitamin E is naturally occurring free radical scavenger and their presence also assist various other mechanisms in decreasing numerous disruptive free radical processes, including LPO (Bansal and Bilaspuri, 2009). Vitamin C and E are major antioxidants naturally present in mammalian semen against ROS to protect sperm from lipid peroxidation and to maintain its integrity (Bilodeau et al., 2001;Gadea et al., 2004;Bucak et al., 2008;Andrabi, 2009;Akhter et al., 2011). Concentration of antioxidant decreased during freeze-thawing process by dilution of semen with extender and excessive generation of ROS molecules (Andrabi, 2009;Kumar et al., 2011).
Factors affecting freezability
It is found that buffalo spermatozoa are more susceptible to risks during freezing and thawing procedures than cattle spermatozoa, thus resulting in lower fertilizing capacity (Raizada et al., 1990;Andrabi et al., 2008). Moreover, there are specific biochemical factors that affect the capability of spermatozoa to prevent hazards caused by the cryogenic procedures. One of the many possible causes of lower freezability of buffalo bull semen compared to cattle bull can be due to the differences in the lipid ratio of the spermatozoa (Jain and Anand 1976; Tatham 2000; European Regional Focal Point on Animal Genetic Resources, 2003) due to presence of high phospholipids content found in buffalo sperm plasma membrane (Cheshmedjieva and Dimov, 1994). Therefore, there is a requirement to develop biochemically defined extenders and cryogenic protocols that are species specific, and may result in the improvement of viability and fertility of frozen thawed buffalo spermatozoa.
Diluter components Buffer
A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is added to it. In various species considerable work has already been done on this aspect for diluter preparation. The composition of the diluter (extender) is decided on the basis of storage temperature of the semen, duration and need a suitable buffer for sperm survival during cryopreservation (Rasul et al., 2000). Ideally, a buffer should have following features (i) Minimum salt effects/ buffer concentration (ii) pH between 6 to 8, favorably 7 (iii) Maximum water solubility (iv) Minimum solubility in all other solvents (v) Minimum temperature effects (vi) Well behaved cations interaction (vii) Better ionic strengths and chemical stability (Bates 1961;Good et al., 1966;Good and Izawa 1972;Keith and Morrison, 1981;Andrabi, 2009).
A most suitable buffering system for buffalo bull semen cryopreservation which should possess composition close to natural medium and help in maintaining fertility of the frozen semen. Beginning from the use of various organic buffers for the cryopreservation of the bull semen (Mughal et al., 2017., Foote, 1970. In this consider, Matharoo and Singh (1980) evaluated citrate, Tris or citric acid as buffers for deep-freezing of buffalo spermatozoa. They found during freezing a minimal loss of post-thawed motility with Tris-based extender. However, Chinnaiya and Ganguli (1980) establish better post-thaw sperm motility with Tris-based extender than citrate or citric acid-based extenders and reported spermatozoa chilled (frozen) in citrate and Tris-based extender showed alike degree of acrosomal damage and similar recovery rates and Ahmad et al., (1986) reported that Tris-citric acid based extender is fit for the freezing of buffalo bull spermatozoa regarding post-thaw motility and survivability while Dhami and Kodagali (1990) found that Tris-based extender improved the freezability of buffalo bull spermatozoa.
Identically, in buffalo bull spermatozoa, Singh et al., (1990Singh et al., ( , 1991 found that minimal release of lactic dehydrogenase and sorbitol dehydrogenase during semen cryopreservation using Tris-based extender followed by citrate and citric acid extenders. Dhami et al., (1994) reported that Tris-based extender provided higher post-thaw spermatozoa motility while evaluated superior results with Tris-based buffer as compared to Laiciphos and Biociphos. Rasul et al., (2000) also found ameliorated semen motility rate using Tris citrate as compared to tri-sodium citrate, Tris-Tes or Tris-Hepes and also found that Tris citrate was suitable buffer for semen cryopreservation. Under other conditions, Oba et al., (1994) and Chachur et al., (1997) found nearest effects on semen motility rate, acrosomal integrity and post thaw motility using Tes which has equal value to Tris-based extender.
From these above mentioned results and studies, it is recommended that zwitterion buffers as a superior option for buffalo bull semen dilution or extension, particularly, Tris-citric acid may issue the most satisfactory buffering system to improve the post-thaw freezability and also fertility of buffalo spermatozoa. Graham et al., (1972) reported that the pH of zwitterions buffers is nearest to the pKa (acid dissociation constant) and it is minimal affected by temperature.
Antibiotics
The viability or fertility of cryopreserved bovine spermatozoa is extremely affected either directly or indirectly by presence of bacteria in semen (Thibier and Guerin 2000;Morrell 2006). So, control of these bacteria by the addition of various antibiotics in the semen diluters to achieve maximum conception rate through artificial insemination (AI). Sansone et al., (2000) and Akhter et al., (2008) were generally added benzyl penicillin 1000 IU ⁄ ml and streptomycin sulphate 1000 lg ⁄ ml alone or in combination as a freezing diluents in semen extender of buffalo bull. However, an inefficient combination of streptomycin and penicillin (SP) in buffalo bull semen to control of bacteriospermia by reason of SP was deleterious to post-thaw quality of spermatozoa (Gangadhar et al., 1986;Aleem et al., 1990;Ali et al., 1994;Amin et al., 1999). Ahmed and Greesh (2001) reported that bacteria separated from buffalo bull semen were resistant to penicillin. However, the antibiotics of better choice to be added in semen extender for efficient cryopreservation of buffalo spermatozoa are gentamicin (500 lg ⁄ ml) or amikacin (500 lg ⁄ ml) or norfloxacin (200 lg ⁄ ml). Recently, a newly combination of gentamicin tylosin and lincospectin, GTLS has manifest extremely capacity to control bacteria and spermatozoal quality present in buffalo bull semen (Hasan et al., 2001;Akhtar et al., 2008). The evaluating of a broad range of antibiotics alone and in combinations is recommended to increase the quality of cryopreserved buffalo bull semen.
Cryoprotectant
Cryodamage has been attributed to ice crystal formation, membrane alteration, oxidative stress, osmotic changes, cryoprotectant toxicity and cold shock during cryopreservation (Watson and Martin, 1975). So, Optimum freezing and thawing rates, suitable cryoprotectant and composition of diluter (extender) are key factors for successful semen cryopreservation (Hammerstedt et al., 1990;Curry et al., 1994) Semen cryopreservation causes deleterious effects regarding biochemical, functional and sperm ultra structural damage (Watson, 2000) causing in a depletion of membrane integrity, acrosome integrity and motility (Woelders et al., 1997 andCeleghini et al., 2007) and fertilizing ability (Purdy, 2006). During the cryopreservation, cryoinjuries are produced and can be lowered and significant enhancement can be obtained through using of cryoprotectants in the semen extender (Holt, 2000 andJohnson et al., 2000). On a large scale, these cryoprotectants are classified into two categories (permeable and non permeable). Permeable cryoprotectants include methanol, butanediol, glycerol, 1, 2proparediol, ethylene glycol, propylene glycol and dimethylsulfoxide (DMSO). These cryoprotectants act as intra-cellularly and extra-cellularly have capability to move through the sperm plasma membrane and, reposition the membrane proteins, reduce formation of intracellular ice and thus protect the spermatozoa from damage (Holt, 2000). Non permeable cryoprotectants comprise mannose, raffinose egg yolk, amino acids, sucrose, xylose, fructose, trehalose, dextran, lactose, polyvinyl pyrollidone (PVP), amides and fatless skimmed milk which do not pierce the sperm membrane (Aisen et al., 2000). Cryoprotectants lower the freezing temperature and finally reduce extracellular ice formation (Kundu et al., 2002). The optimum levels of glycerol and glycerolization are important key factor for the cryopreservation of buffalo semen. They also reported that post-thaw motility of spermatozoa was significantly better in a 5% glycerol extender, whereas the percentage of acrosomal integrity was higher in spermatozoa extended in 3% or 5% glycerol than in spermatozoa extended in 7% glycerol (Jainudeen and Das., 1982). Tris-and milkbased diluents have better level of glycerol as 6% and 9% glycerol for the sodium citrate diluent to acquire better post-thaw motility for buffalo spermatozoa Glycerol is a small, poly-hydroxylated solute with a high solubility in water, and a low toxicity during short-term exposure to living cells. It can interact by hydrogen bonding with water and can permeate across the limiting plasma membrane of many different cell types (Fuller and Paynter, 2004). Ramakrishan and Ariff, (1994); Nastri et al., (1994) also reported that the reduction in glycerol below 5% decreased the post-thaw motility and acrosome integrity of spermatozoa in the extenders. Holt (2000b); Medeiros et al., (2002) investigated that the physiological role of glycerol as cryoprotectant takes place by lowering the freezing point of water, replacing intracellular water, binding with metallic ions and by reducing the electrolyte profile in the unfrozen portion. So, Glycerol (6 to 7%) is commonly used as cryoprotectant for buffalo bull semen. Abbas and Andrabi (2002) studied the effects of different concentrations of glycerol on post-thaw sperm quality and reported that the spermatozoa cryopreserved in 7% were significantly superior to those in other concentrations of glycerol as determined by post-thaw motility, plasma membrane integrity and survivability. Singh et al., (2006) found that single step of glycerolization is more suitable for the cryopreservation of buffalo spermatozoa for post-thaw motility. Dimethyl sulfoxide (DMSO) is a rapid penetrating cryoprotectants having lower molecular weight than glycerol. Yu and Quinn (1994) evaluated that DMSO may inhibit harmful effects of hydroxyl radicals and these radicals appear during cell respiration and are detrimental to cell (Johnson and Nasr-Esfahani 1994). Rasul et al., (2007) investigated the synergistic effects of dimethyl sulfoxide (DMSO) on cryoprotection ability of glycerol during cryopreservation of buffalo sperm in terms of motion characteristics, acrosome morphology and plasma membrane integrity using tris citric acid extender differing in glycerol and DMSO concentrations at various temperatures. DMSO in combination with glycerol is superior in providing cryoprotection in cattle bull (Snedeker and Gaunya 1970) rabbit and buck spermatozoa (Bamba and Adams 1990). During cryopreservation, DMSO has harmful toxic effect rather than the osmotic shock because of the lower molecular weight of DMSO, its penetrating ability into the cell is higher than glycerol (Rasul et al., 2007). Glycerol is useful for the sperm as its freezing point is much lower than water. Hence, it is suggested that a extender containing glycerol concentration of 5-7% may be suitable for the cryopreservation of buffalo bull spermatozoa. Under other conditions, development of less toxic and more powerful cryoprotectant could make an important contribution in improving post thaw quality of buffalo spermatozoa.
The other important component of semen extenders is egg yolk in the buffalo and and most of the livestock species . Egg yolk containing low density lipoproteins (LDL) is highly responsible for sperm protection during cryo-preservation (Pace and Graham 1974;Watson 1976). LDL provides protection to sperm by stabilizing the membrane to adhere with sperm membrane. Sansone et al., (2000); reported that egg yolk which is commonly used at a concentration of 20% in semen extender, is mandatory for freezing of buffalo semen. The higher concentration of egg yolk in extender may have detrimental effects combined with toxicity of dead spermatozoa resulting in lower post-thaw sperm quality (Shannon 1972) probably due to the raised substrate available for hydrogen peroxide formation (Tosic and Walton 1950). Sahni and Mohan (1990) reported different levels of egg yolk in semen extender for cryopreservation of buffalo semen and concluded that the concentration of egg yolk in the extender could be reduced from 20% to 5% without any compromise in post-thaw motility of spermatozoa. Similarly Kumar et al., (1994) reported that 5% egg yolk prove better than 10% and 20% while Singh et al., (1999) concluded 10% concentration of egg yolk was superior for freezing of buffalo semen with regards to pre-freeze and postthaw sperm motility and survivability of spermatozoa. Egg yolk containing lecithin and proteins preserve the lipoprotein sheath of spermatozoa . Sahni and Mohan, (1990) found that egg yolk stimulates enzymes found in the spermatozoa which cause deamination of amino acids causing damage to spermatozoa during storage period. So, Egg yolk is an important and necessary component while diluting semen in the extenders in bovine and many species during cryopreservation protocols (Shannon and Curson, 1983;Priyadharsini et al., 2011). The extender containing duck egg yolk improved freezability of buffalo bull spermatozoa as compared to other avian egg yolks . Polyethylene glycol (PEG) is a non-permeable cryoprotectant and may decrease the process of ice nucleation during cryogenic process and protecting the cellular membrane. Cheshmedjieva et al., (1996) found that the effect of addition of PEG 20 to egg yolk based freezing medium on the lipids in buffalo spermatozoa and concluded that incorporation of PEG 20 in semen extender preserved the lipids of frozen buffalo spermatozoa. In future, further studies on PEG 20 may be a better alternate for the cryopreservation of buffalo spermatozoa.
Sugars like as raffinose, trehalose lactose, sucrose and dextrans are non-permeable cryoprotectant and also added in semen extender (Nagase et al., 1964). Sugars are not capable of diffusing across a plasma membrane and produce an osmotic pressure inducing cell dehydration and lower incidence of intracellular ice formation. These sugars also interact with reorganizing the membrane and phospholipids in the plasma membrane which results in surviving of sperm during cryopreservation process (Molinia et al., 1994;Aisen et al., 2002). Dhami and Sahni (1993) reported that the post-thaw quality of spermatozoa was superior with raffinose (1%) in Tris-based extender compared to other extenders in terms of release of lactate dehydrogenase. The newer international trends in disease control consider the ingredients of animal origin (egg yolk) to be a source of contamination to the semen (Bousseau et al., 1998), hence emerges the need of using non-animal sources. It is feasible that extenders having ingredients of animal origin (egg yolk) can be the source of pathogens resulting in the contamination of semen (Bousseau et al., 1998;Marco-Jimenez et al., 2004;Ruigh et al., 2006). In this regard, lecithin from non-animal source like soya needs to be trialed as a non-permeable cryoprotectant in extender for cryopreservation of buffalo spermatozoa.
Other additives
Attempts have been made to enhance the freezability of bubaline semen by adding different substance such as metabolic stimulants, detergents, antioxidants and chelating agents due to decrease the harmful effects of cryogenic procedures. Bhosrekar et al., (1990) found that the effect of addition of caffeine or triethanolamine lauryl sulphate to Tris citric acid based extender and evaluated that the incorporation of the detergent upgraded the post thaw spermatozoa motility. Detergents have protective effects and may be exerted directly on the sperm membrane or emulsifying the egg yolk lipids which becomes immediately available to the plasma lemma during cryopreservation (Graham et al., 1971;Arriola and Foote 1987;Buhr and Pettitt 1996). Singh et al., (1996) found that incorporation of ascorbic acid (2.5 mM) in the buffalo bull semen extender yielded a significantly enhance the post-thaw motility and longevity. Although, Kolev (1997) reported that incorporation of 0.3 mg ⁄ ml of vitamin E in extender had exhibit better effects on acrosomal integrity, survivability and motility of cryopreserved buffalo bull spermatozoaand tocopherol (vitamin E) obstructs lipid peroxidation (LPO) in membranes, acting as a scavenger of lipid peroxyl and alkoxyl radicals, thus preventing oxidative damage in cryopreserved bovine semen (Beconi et al., 1991). Fabbrocini et al., (2000) recommended that addition of 1.25 mM sodium pyruvate into the extender resulting in significantly improved post-thaw progressive motility and viability due to its antioxidant property during cryopreservation of buffalo semen. It is also reported that addition of oviductal proteins obtained from various stages of the oestrous cycle into extender affected the post-thaw semen characteristics due to lowered the LPO levels in buffalo spermatozoa during cryopreservation (Kumaresan et al., 2006). Recently, Shukla and Misra (2007) studied that addition of Bradykinin (2 ng ⁄ ml) in Trisbased extender to improve post thaw buffalo semen characteristics during cryopreservation. Ijaz et al., (2009) found that the Butylatedhydroxytoluene (BHT) at concentration 1.0 and 2.0 mM in tris citrate egg yolk extender provided better results for cryopreservation of buffalo bull semen. From the above cited studies, the incorporation of some additives in buffalo semen extender in terms of improvement in the quality of frozen-thawed buffalo spermatozoa.
Osmotic pressures
Semen dilution is a prime importance to maintain fertilizing potential of cryopreserved buffalo semen (Rasul et al., 2000). In the extender the concentration of the solutes become high, the osmotic pressure is elevated. So, number of solute particles affects the osmotic pressure as well as freezing point of the solvents in a solution. When spermatozoa are exposed to hyperosmolal solution, more extra cellular ice crystals are formed (Watson, 1995) and vice versa. Polyhydric alcohols and water have high osmotic permeability coefficient which increases the shifting of these substance across the palsma membrane of the spermatozoa during cryopreservation (Noiles et al., 1993). Spermatozoa either swell or shrink under hypotonic/ hypertonic solution (DU et al., 1994;Gilmore et al., 1996). Any change in the osmotic pressure during cryopreservation causing damage of plasma membrane of spermatozoa. Hence, osmotic pressure plays a crucial role in semen cryopreservation and affects the frozen semen quality (Khan and Ijaz, 2008). The buffalo bull semen have been found different osmotic pressures, which include 293.33 mOsm/kg , 268.81 mOsm/L (Khan and Ijaz, 2008) and 289.4 mOsm/kg (Mughal et al., 2013). From above cited studies, it is concluded that buffalo bull semen has osmotic pressure lower than cattle semen.
Semen processing
Preliminary processing
The semen collection station is commonly located near the semen laboratory and it is commonly suggested that semen should be processed as early as possible after collection. No changes have been recognized in morphology, motility and survivability of spermatozoa, if the semen was processed within 1 h of collection (Fabbrocini et al., 1995). Generally semen dilution, having all compulsory constituents, is done at 30oC to 37oC. Vale et al., (1991) suggested the ejaculates should be kept for 10 to 15 minutes in its own plasma, after sometimes semen of buffaloes.
To prevent agglutination immediately added the diluents very soon after collection may and also maintain the motility of spermatozoa. On the other words, there is delay in semen processing immediately after semen collection, it should be diluted with suitable extender and stored at 5ºC (Televi et al., 1994).
Semen dilution
In case of buffalo semen freezing, one step or two steps dilution methods are being used.
Del correlated both methods (one and two steps) using tris-egg yolk-based extenders and reported that the two-step method provide superior results with long 6 h equilibration, while one-step dilution method required shorter period 2 to 4 h equilibration time before freezing. Fabbrocini et al., (1995) reported that in two step dilutions method, addition of glycerol showed better sperm motility when glycerol was added 1 h before freezing. Del Sorbo et al., (1995) also found two step semen dilution methods using sodium pyruvate (1.25 mM) with second dilution 1h prior to freezing the semen.
Cooling rates, equilibration time and freezing
After semen dilution, the semen is cooled at a temperature of 4 O C or 5 O C. Cooling is a necessary to spermatozoa to lowered metabolism. Diluted semen is cooled slowly to avoid cold shock. Cold shock is produced to impair function of membrane proteins that are necessary for structural integrity or ion metabolism of spermatozoa (Watson 2000). During freezing, buffalo spermatozoa are more susceptible to cryoinjury than cattle spermatozoa (Raizada et al., 1990). These cryoinjury can be lowered by optimizing the cooling and freezing rates and using suitable diluting media . Talevi et al., (1994) studied both slow and fast cooling protocols in buffalo bull semen and found the slow cooling (28°C to 5°C in 1 hour) and rapid cooling (28°C to 5°C in 15 minutes) protocols had no significant differences in post-thaw motility of spermatozoa. Mazur et al., (1972);and Mazur, (1977) found that spermatozoa are exposed to high salt concentration and osmolality with changes in PH during slow cooling process, While during fast cooling, intracellular water may not pass out of membrane, resulting in intracellular ice crystals formation. Sahni and Mohan (1990) reported that no significant difference on post-thaw sperm motility between these two cooling rates. In terms of other study, Sukhato et al., (2001) found that cooling rates of 20 or 30°C ⁄ min yielded better progressive post thaw motility and fertility using the effects of three cooling rates (10, 20 or 30°C ⁄ min) from 4°C to each of either -40°C, -80°C or -120°C before plunging into liquid nitrogen. Anzar et al., (2010) worked at different cooling rates for buffalo bull spermatozoa and reported higher motility, plasma membrane integrity and acrosomal morphology at high freezing rates of -30oC/ minute. The beneficial effects of slow cooling rate of diluted semen are considered at 5 O C due to rapid penetration of glycerol in the cell membrane (Ennen et al., 1976;Gilbert and Almquist, 1978). However investigators prefer slow cooling rate of 0.2 to 0.4 0 C/minute for the pre-freezing processing of the buffalo bull semen.
Researchers found different equilibration durations during cryopreservation. Regarding equilibration, it is generally called the "glycerol equilibration" period, during this stage; glycerol rapidly penetrates into the spermatozoa to establish equilibrium between its intracellular and extracellular concentration and other osmotically active extender components (Salamon and Maxwell, 2000). Singh et al., (1989); and Del Sorbo et al., (1995) recommended short equilibration periods of 2 to 4 h while another investigators favored longer duration of about 6 h (Haranath et al., 1990;Televi et al., 1994). It is commonly trusted that semen should be kept at 5 o C for not less than 2 h and not more than 6 h before freezing for cryopreservation of buffalo bull semen. Cassou (1964) reported that semen is filled and sealed commonly at 5 o C in the straws of 0.25 ml or 0.5 ml capacity. Straws of 0.25 ml are generally used because of their cost and storage space. Filled and sealed straws are placed in horizontal position 1 to 4 cm above liquid nitrogen gas for 10 to 20 minutes before plunging into liquid nitrogen gas at -196 o C.
Thawing rates and temperature
Different thawing temperature and time were used by the researchers. Mazur, (1984) found that fast thawing of semen prevents formation of recrystallization of water. Rao et al., (1986) compared two thawing rates (37 o C for 30 s and 75 o C for 9 s) and found that the best value for post-thaw motility was observed for semen thawed at 37 o C for 30 s. Dhami et al., (1996) reported different thawing rates at 4 o C for 5 min, 40 o C for 1 min or 60 o C for 15 s and found that thawing of semen at 60 o C for 15 s yielded high post-thawing spermatozoal recovery and longevity. El-Amrawi (1997) worked at different thawing procedure and got best fertility rates when semen was thawed at 35 o C for 60 seconds.
Future directions
Future research should highlight on freezing protocols improvement for lower spermatozoa damage during buffalo bull semen cryopreservation. To achieve this goal, diluents composition, freezing protocols along with the improvement of presently used extenders must be focused for buffalo semen cryopreservation. Commercially available extenders i.e. Triladyl (Minitub Germany), Biociphos (IMV, France) and Laciphos (IMV, France), etc. should also be tried for cryopreservation of buffalo bull semen. Therefore, a better understanding of the fundamental principle of cryopreservation of buffalo spermatozoa is necessary according to the specific requirements. Moreover, there is a need to develop biochemically defined extenders and cryogenic procedures that may result in improvement in viability and fertility of frozen thawed buffalo spermatozoa.
Italy. 1: 63-67. Del Sorbo, C., G. Fasano, A. Fabbrocini, S.L. Lavadera and G. Sansone. (1995). Piruvato quale substrato energetico in extenders crioprotettivi. Effetti sulla motilitaallo scongelamento di spermatozoi bufalini Bubalus bubalis. In Proceedings of 7th Meeting Nazionale "Studio Sulla Efficienza Riproduttiva Degli Animali Diinteresse Zootecnico." Bergamo, Italy. l: 585-588. DeLamirande, E., Jiang, H. and Zini, A. (1997).
Reactive oxygen species and sperm physiology. Rev. Reprod. 2: 48-54. Dhami AJ, Sahni KL, (1993). Effect of extenders, additives and deep freezing on the leakage of lactic dehydrogenase from cattle and buffalo spermatozoa. Indian J Anim Sci 63, 251-256. Dhami AJ, Sahni KL, Mohan G, Jani VR, (1996).
Effects of different variables on the freezability, post-thaw longevity and fertility of buffalo spermatozoa in the tropics. Theriog-enology 46, 109-120. Dhami, A.J. and K.L. Sahni. (1994). Effects of various cooling from 30oC to 5oC, equilibration and diluents treatments on freezability, post-thaw thermoresistance, enzyme leakage and fertility of bubaline spermatozoa. Buffalo J., 2: 147-159. Dhami, A.J. and S.B. Kodagali. (1990).
Freezability, enzyme leakage and fertility of buffalo spermatozoa in relation to the quality of semen ejaculates and extenders. Theriogenology, Du, J., J. Tao
, F.W. Kleinhans, A.T. Teter and J.K. Critser. (1994). Determination of boar spermatozoa water volume and osmotic pressure. Theriogenology, 42: 1183-1191. El-Amrawi, G.A. (1997). Effect of thawing time and post-thaw temperature on fertility of buffalo spermatozoa frozen in straws. In Proceedings of 5th World Buffalo Congress, Caserta, Italy. 1: 850-855. Ennen, B.D., W.E. Berndtson, R.G. Mortimer and B.W. Pickett. (1976). Effect of processing procedures on motility of bovine spermatozoa frozen in 0.25 ml straws. J. Anim. Sci., 43: 651-656. European Regional Focal Point on Animal Genetic Resources, (2003). Guidelines for the constitution of national cryo
Effect of different glycerol concentrations on motility before and after freezing, recovery rate, longevity and plasma membrane integrity of Nili-Ravi buffalo bull spermatozoa. A Abbas, Smh Andrabi, Pak Vet J. 22Abbas A, Andrabi SMH, (2002). Effect of different glycerol concentrations on motility before and after freezing, recovery rate, longevity and plasma membrane integrity of Nili-Ravi buffalo bull spermatozoa. Pak Vet J 22, 1-4.
Note on the freezing of buffalo semen by land shut method and fertility of frozen semen in comparison to liquid semen under field conditions. H L Abhi, Indian J. Anim. Sci. 52Abhi, H. L. (1982). Note on the freezing of buffalo semen by land shut method and fertility of frozen semen in comparison to liquid semen under field conditions. Indian J. Anim. Sci. 52: 809-811.
Sephadex and sephadex ion-exchange filtration improves the quality and freezability of low grade buffalo semen ejaculates. Z Ahmad, M Anzar, M Shahab, N Ahmad, Smh Andrabi, Theriogenology. 59Ahmad Z, Anzar M, Shahab M, Ahmad N, Andrabi SMH, (2003). Sephadex and sephadex ion-exchange filtration improves the quality and freezability of low grade buffalo semen ejaculates. Theriogenology 59, 1189-1202.
Post thaw survival and fertility of frozen bull spermatozoa treated with antibiotics and detergent. K Ahmad, R H Foote, J. Dairy Sci. 69535Ahmad, K. and Foote, R.H. (1986). Post thaw survival and fertility of frozen bull spermatozoa treated with antibiotics and detergent. J. Dairy Sci., 69: 535.
Effect of antibiotics on the bacterial load and quality of semen of Murrah buffalo bulls during preservation. K Ahmed, M Greesh, Indian J. Anim. Reprod. 22Ahmed, K. and M. Greesh. (2001). Effect of antibiotics on the bacterial load and quality of semen of Murrah buffalo bulls during preservation. Indian J. Anim. Reprod., 22: 79-80.
Cryopreservation and post-thawed fertility of ram semen frozen in different trehalose concentrations. E G Aisen, V H Medina, A Venturino, Theriogenology. 57Aisen EG, Medina VH, Venturino A, (2002). Cryopreservation and post-thawed fertility of ram semen frozen in different trehalose concentrations. Theriogenology 57, 1801- 1808.
Effect of trehalose and EDTA on cryoprotective action of ram semen diluents. E G Aisen, H L Alvarez, A Venturino, J J Garde, Theriogenology. 53Aisen, E.G., H.L. Alvarez, A. Venturino and J.J. Garde. (2000). Effect of trehalose and EDTA on cryoprotective action of ram semen diluents. Theriogenology, 53: 1053- 1061.
Effect of antibiotics in extender on bacterial and spermatozoal quality of cooled buffalo (Bubalus bubalis) bull semen. S Akhter, M S Ansari, Smh Andrabi, N Ullah, M Qayyum, Reprod Domest Anim. 43Akhter S, Ansari MS, Andrabi SMH, Ullah N, Qayyum M, (2008). Effect of antibiotics in extender on bacterial and spermatozoal quality of cooled buffalo (Bubalus bubalis) bull semen. Reprod Domest Anim 43, 272- 278.
Storage of Nili-Ravi buffalo (Bubalus bubalis) semen in skim milk extender supplemented with ascorbic acid and α tocopherol. S Akhter, B A Rakha, M S Ansari, S M H Andrabi, N Ullah, Pak. J. Zool. 43Akhter, S., Rakha, B. A., Ansari, M. S., Andrabi, S. M. H. and Ullah, N. (2011). Storage of Nili-Ravi buffalo (Bubalus bubalis) semen in skim milk extender supplemented with ascorbic acid and α tocopherol. Pak. J. Zool. 43: 273-277.
Occurrence of pathogenic bacteria in buffalo semen. M Aleem, R A Chaudhry, N U Khan, A R Rizvi, R Ahmed, Buffalo J. 6Aleem M, Chaudhry RA, Khan NU, Rizvi AR, Ahmed R, (1990). Occurrence of pathogenic bacteria in buffalo semen. Buffalo J 6, 93-98.
Comparative effects of combiotic, ampicillin and gentamycin sulphate on motility percentage, liveability and absolute index of liveability in the buffalo bull semen. H Ali, A Din, H A Samad, S Ali, M A Sabri, Pak Vet J. 14Ali H, Din A, Samad HA, Ali S, Sabri MA, (1994). Comparative effects of combiotic, ampicillin and gentamycin sulphate on motility percentage, liveability and absolute index of liveability in the buffalo bull semen. Pak Vet J 14, 223-227.
Spontaneous lipid peroxidation in rabbit epididymal spermatozoa, its effect on sperm motility. J G Alvarez, B T Storey, Biol. Reprod. 27Alvarez, J. G. and Storey, B. T. (1982). Spontaneous lipid peroxidation in rabbit epididymal spermatozoa, its effect on sperm motility. Biol. Reprod. 27: 1102- 1108.
Trial to control Chlamydia psittaci in processed buffalo-semen. A S Amin, G M Darwish, S Z Maha, H M Hassan, Assi Vet Med J. 40Amin AS, Darwish GM, Maha SZ, Hassan HM, (1999). Trial to control Chlamydia psittaci in processed buffalo-semen. Assi Vet Med J 40, 319-332.
Factors Affecting the Quality of Cryopreserved Buffalo (Bubalus bubalis) Bull Spermatozoa. Smh Andrabi, Reprod Dom Anim. 44Andrabi SMH, (2009). Factors Affecting the Quality of Cryopreserved Buffalo (Bubalus bubalis) Bull Spermatozoa. Reprod Dom Anim 44, 552-569.
Effect of two different antibiotic combinations on fertility of frozen buffalo and Sahiwal bull semen. Smh Andrabi, N Ahmad, A Abbas, M Anzar, Pak Vet J. 21Andrabi SMH, Ahmad N, Abbas A, Anzar M, (2001). Effect of two different antibiotic combinations on fertility of frozen buffalo and Sahiwal bull semen. Pak Vet J 21, 166- 169.
Duck egg yolk in extender improves the freezability of buffalo bull spermatozoa. Smh Andrabi, M S Ansari, N Ullah, M Anwar, A Mehmood, S Akhter, Anim Reprod Sci. 104Andrabi SMH, Ansari MS, Ullah N, Anwar M, Mehmood A, Akhter S, (2008). Duck egg yolk in extender improves the freezability of buffalo bull spermatozoa. Anim Reprod Sci 104, 427-433.
Response of buffalo spermatozoa to low temperatures during cryopreservation. M Anzar, Z Rasul, T A Ahmed, N Ahmad, Reprod. Fert. Develop. 22Anzar, M., Z. Rasul, T.A. Ahmed and N. Ahmad. (2010). Response of buffalo spermatozoa to low temperatures during cryopreservation. Reprod. Fert. Develop., 22: 871-880.
Factors affecting the efficiency of artificial insemination in cattle and. M Anzar, U Farooq, M A Mirza, M Shahab, N Ahmed, Vet. J. 23Anzar, M., Farooq, U., Mirza, M. A., Shahab, M. and Ahmed, N. (2003). Factors affecting the efficiency of artificial insemination in cattle and buffalo in Punjab, Pakistan. Pak. Vet. J. 23: 106-113.
Assessment of motility and membrane peroxidation of bull spermatozoa in the presence of different concentration of vitamin C. M Arabi, S R Seidaie, Vet. Med. J. Shahrekord. 2Arabi, M. and Seidaie, S. R. (2008). Assessment of motility and membrane peroxidation of bull spermatozoa in the presence of different concentration of vitamin C. Vet. Med. J. Shahrekord. 2: 39-46.
Glycerolation and thawing effects on bull spermatozoa frozen in detergent-treated egg yolk and whole egg extenders. J Arriola, R H Foote, J Dairy Sci. 70Arriola J, Foote RH, (1987). Glycerolation and thawing effects on bull spermatozoa frozen in detergent-treated egg yolk and whole egg extenders. J Dairy Sci 70, 1664-1670.
. J L Bailey, A Morrie, N Cormier, Bailey JL, A Morrie and N Cormier, (2003).
Semen cryopreservation: success and persistent in farm species. Canadian J. Anim. Sci. 83Semen cryopreservation: success and persistent in farm species. Canadian J. Anim. Sci., 83:393-401.
Freezing rabbit semen by use of BF5 diluent. K Bamba, C E Adams, Lab Anim. 24Bamba K, Adams CE (1990). Freezing rabbit semen by use of BF5 diluent. Lab Anim 24:172-175.
Antioxidant effect of vitamin E on motility, viability and lipid peroxidation of cattle spermatozoa under oxidative stress. A K Bansal, G S Bilaspuri, Anim. Sci. Pap. Rep. 27Bansal, A. K. and Bilaspuri, G. S. (2009). Antioxidant effect of vitamin E on motility, viability and lipid peroxidation of cattle spermatozoa under oxidative stress. Anim. Sci. Pap. Rep. 27: 5-14.
Cryopreservation of domestic animal sperm cells. J P Barbas, R D Mascarenhas, Cell Tissue Bank. 10Barbas, J. P. and Mascarenhas, R. D. (2009). Cryopreservation of domestic animal sperm cells. Cell Tissue Bank. 10: 49-62.
Amine buffers for pH control. R G Bates, Bates RG, (1961). Amine buffers for pH control.
. Ann N Y Acad Sci. 92Ann N Y Acad Sci 92, 341-356.
Influence of antioxidants on SOD activity in bovine sperm. M Beconi, M Affranchino, L M Schang, N M Beorlegui, Biochem Int. 3Beconi M, Affranchino M, Schang LM, Beorlegui NM, (1991). Influence of antioxidants on SOD activity in bovine sperm. Biochem Int 3, 545-553.
Studies on the effect of additives to semen diluent. M R Bhosrekar, J R Purohit, B R Mangurkar, Indian J. Anim. Reprod. 11Bhosrekar, M.R., J.R. Purohit and B.R. Mangurkar. (1990). Studies on the effect of additives to semen diluent. Indian J. Anim. Reprod., 11: 85-88.
Thiols prevent H2O2-mediated loss of sperm motility in cryopreserved bull semen. J F Bilodeau, S Blanchette, C Gagnon, M A Sirard, Theriogenology. 56Bilodeau, J. F., Blanchette, S., Gagnon, C. and Sirard, M. A. (2001). Thiols prevent H2O2- mediated loss of sperm motility in cryopreserved bull semen. Theriogenology. 56: 275-286.
Current status in avian semen cryopreservation. World"s. E Blesbois, Poult. Sci. J. 63Blesbois E. (2007). Current status in avian semen cryopreservation. World"s Poult. Sci. J., 63: 213-222.
Comparison of bacteriological qualities of various egg yolk sources and the in vitro and in vivo fertilizing potential of bovine semen frozen in egg yolk or lecithin based diluents. S Bousseau, J P Brillard, L Marquant, B Guienne, B Guerin, A Camus, M Lechat, Theriogenology. 50Bousseau S, Brillard JP, Marquant L, Guienne B, Guerin B, Camus A, Lechat M, (1998). Comparison of bacteriological qualities of various egg yolk sources and the in vitro and in vivo fertilizing potential of bovine semen frozen in egg yolk or lecithin based diluents. Theriogenology, 50, 699-706.
Effect of antioxidants and oxidative stress parameters on ram semen after the freezethawing process. M N Bucak, A Atessahin, A Yuce, Small Ruminant Res. 75Bucak, M. N., Atessahin, A. and Yuce, A. (2008). Effect of antioxidants and oxidative stress parameters on ram semen after the freeze- thawing process. Small Ruminant Res. 75: 128-134.
Frozen-thawed boar sperm: isolation of membranes and fluidity measurement. Buffalopedia, www.buffalopedia.cirb.res.in Buhr MM. 31Pettitt MJBuffalopedia. 2015, www.buffalopedia.cirb.res.in Buhr MM, Pettitt MJ, (1996). Frozen-thawed boar sperm: isolation of membranes and fluidity measurement. Reprod Domest Anim 31, 147-152.
La methode de paillettes en plastique adaptee a la generalisation de la congelation. R Cassou, Proceedings of 5th International Congress on Animal Reproduction and Artificial Insemination. 5th International Congress on Animal Reproduction and Artificial InseminationTrento, Italy4Cassou, R., (1964). La methode de paillettes en plastique adaptee a la generalisation de la congelation. In Proceedings of 5th International Congress on Animal Reproduction and Artificial Insemination, Trento, Italy. 4: 540-546.
Practical techniques for bovine sperm simultaneous fluorimetric assessment of plasma, acrosomal and mitochondrial membranes. E C C Celeghini, R P Arruda, A F C Andrade, J Nascimento, C F Raphael, Reproduction of Domestic. Animals. 42Celeghini, E. C. C., Arruda, R. P., Andrade, A. F. C., Nascimento, J., Raphael, C. F. (2007).Practical techniques for bovine sperm simultaneous fluorimetric assessment of plasma, acrosomal and mitochondrial membranes. Reproduction of Domestic. Animals, v. 42, p. 479-488.
Equilibrium time influence on motility, vigour and membrane integrity of thawed buffalo semen using triladyl, glycine-egg yolk and tes extenders. M G M Chachur, E Oba, C I M Gonzales ; Vale, W G Barnabe, V H Mattos, Jca De, Proceedings of 5th World. Borghese, A., S. Failla and V.L. Barile5th WorldBuffalo Congress, Caserta, Italy. International Buffalo Federation, Roma, Italy. Cheshmedjieva SB; Sao Paulo; Roma, ItalyProceedings of 4th World Buffalo Cong.Chachur, M.G.M., E. Oba and C.I.M. Gonzales. (1997). Equilibrium time influence on motility, vigour and membrane integrity of thawed buffalo semen using triladyl, glycine-egg yolk and tes extenders. In Borghese, A., S. Failla and V.L. Barile (eds). Proceedings of 5th World Buffalo Congress, Caserta, Italy. International Buffalo Federation, Roma, Italy. Cheshmedjieva SB, Dimov VN, (1994). Effect of freezing on phospholipid distribution of buffalo spermatozoa plasma membranes. In: Vale WG, Barnabe VH, Mattos JCA de, Proceedings of 4th World Buffalo Cong., Sao Paulo, Brazil. International Buffalo Federation, Roma, Italy, pp. 519-521.
On the lipid composition of buffalo spermatozoa frozen in different cryoprotective media. S B Cheshmedjieva, C N Vaisberg, S I Kolev, Bulgarian J Agric Sci. 2Cheshmedjieva SB, Vaisberg CN, Kolev SI, (1996). On the lipid composition of buffalo spermatozoa frozen in different cryoprotective media. Bulgarian J Agric Sci 2, 23-26.
Freezability of buffalo semen in different extenders. G P Chinnaiya, N C Ganguli, Zbl. Vet. Med. A. 27Chinnaiya, G.P. and N.C. Ganguli. (1980). Freezability of buffalo semen in different extenders. Zbl. Vet. Med. A., 27: 563-568.
Fertility of liquid and frozen semen in Nili Ravi buffaloes. Pak. A R Chohan, J Iqbal, A A Asghar, M A Chaudhary, Vet. J. 12Chohan, A. R., Iqbal, J., Asghar A. A. and Chaudhary, M. A. (1992). Fertility of liquid and frozen semen in Nili Ravi buffaloes. Pak. Vet. J. 12: 4-5.
Osmotic effects on ram and human sperm membranes in relation to thawing injury. Curry Mr, P F Watson, Cryobiology. 31Curry MR and Watson PF. (1994). Osmotic effects on ram and human sperm membranes in relation to thawing injury. Cryobiology 31: 39-46.
Studio preliminare su effetti di vari agenti crioprotettivi sulla motilita di spermatozoi bufalini B. bubalis allo scongelamento. Del Sorbo, C , G Fasano, A Fabbrocini, M J F Nastri, G Sansone, Proceeding of 6th meeting nazionale. Hiemstra SJeeding of 6th meeting nazionaleNetherlands30Publication No. 1 of the European Regional Focal Point onDel Sorbo, C., G. Fasano, A. Fabbrocini, M.J.F. Nastri and G. Sansone. (1994). Studio preliminare su effetti di vari agenti crioprotettivi sulla motilita di spermatozoi bufalini B. bubalis allo scongelamento. In Proceeding of 6th meeting nazionale "Studiodella efficienza riproduttiva deli animali di interesse zootecnico." Bergamo, preservation programmes for farm animals. In: Hiemstra SJ (ed.), Publication No. 1 of the European Regional Focal Point on Animal Genetic Resources. Lelystad, Netherlands, p. 30.
Effect of differential addition of glycerol and pyruvate to extender on cryopreservation of Mediterranean buffalo (B. bubalis) spermatozoa. A Fabbrocini, Del Sorbo, C Fasano, G Sansone, G , Theriogenology. 54Fabbrocini A, Del Sorbo C, Fasano G, Sansone G, (2000). Effect of differential addition of glycerol and pyruvate to extender on cryopreservation of Mediterranean buffalo (B. bubalis) spermatozoa. Theriogenology 54, 193-207.
Effect of cryoprotectant addition mode on freezedthawed Bubalus bubalis semen. A Fabbrocini, C Sorbo, G Fasano, M R Martusciello, G Sansone, Proceedings of 30th Symposium "Reproduction and Animal Breeding: Advance and Strategy. 30th Symposium "Reproduction and Animal Breeding: Advance and StrategyMilano, Italy1Fabbrocini, A., C. Del Sorbo, G. Fasano, M.R. Martusciello and G. Sansone. (1995). Effect of cryoprotectant addition mode on freezed- thawed Bubalus bubalis semen. In Proceedings of 30th Symposium "Reproduction and Animal Breeding: Advance and Strategy", Milano, Italy. 1: 373-374.
Fertility of bull semen at high extension rates in Tris buffered extenders. R H Foote, J. Dairy Sci. 53Foote, R.H. (1970). Fertility of bull semen at high extension rates in Tris buffered extenders. J. Dairy Sci., 53: 1475-1477.
Fundamentals of cryobiology in reproductive medicine. B Fuller, S Paynter, Reprod Biomed Online. 9Fuller B, Paynter S, (2004). Fundamentals of cryobiology in reproductive medicine. Reprod Biomed Online 9, 680-691.
. J Gadea, E Selles, M A Marco, P Copy, C Matas, R Romar, S Ruiz, Gadea, J., Selles, E., Marco, M. A., Copy, P., Matas, C., Romar, R. and Ruiz, S. (2004).
Decrease in glutathione content in boar sperm cryopreservation, effect of the addition of reduced glutathione to the freezing and thawing extenders. Theriogenology. 62Decrease in glutathione content in boar sperm cryopreservation, effect of the addition of reduced glutathione to the freezing and thawing extenders. Theriogenology. 62: 690-701.
Effect of antibiotics on bacterial load in frozen semen of buffalo bulls. K S Gangadhar, A R Rao, G Subbaiah, Indian Vet J. 63Gangadhar KS, Rao AR, Subbaiah G, (1986). Effect of antibiotics on bacterial load in frozen semen of buffalo bulls. Indian Vet J 63, 489-493.
Effects of processing procedures on post-thaw acrosomal retention and motility of bovine spermatozoa packaged in 0.3 ml straws at room temperature. G R Gilbert, J O Almquist, J. Anim. Sci. 46Gilbert, G.R. and J.O. Almquist. (1978). Effects of processing procedures on post-thaw acrosomal retention and motility of bovine spermatozoa packaged in 0.3 ml straws at room temperature. J. Anim. Sci., 46: 225- 231.
Osmotic properties of boar spermatozoa and their relevance to cryopreservation. J A Gilmore, J Du, J Tao, A T Peter, J K Critser, J. Reprod. Fertil. 107Gilmore, J.A., J. Du, J. Tao, A.T. Peter and J.K. Critser. (1996). Osmotic properties of boar spermatozoa and their relevance to cryopreservation. J. Reprod. Fertil., 107: 87-95.
Hydrogen ion buffers. N E Good, S Izawa, Methods Enzymol. 24Good NE, Izawa S, (1972). Hydrogen ion buffers. Methods Enzymol 24, 53-68.
Hydrogen ion buffers for biological research. N E Good, G D Winget, W Winter, T N Connolly, S Izawa, Rmm Singh, Biochemistry. 5Good NE, Winget GD, Winter W, Connolly TN, Izawa S, Singh RMM, (1966). Hydrogen ion buffers for biological research. Biochemistry 5, 467-477.
Preliminary report on procedure and rationale for freezing boar semen. E F Graham, Ahj Rajamannan, Mkl Schmehl, M Maki-Lanrila, R E Bower, AI Digest. 1912Graham EF, Rajamannan AHJ, Schmehl MKL, Maki-Lanrila M, Bower RE, (1971). Preliminary report on procedure and rationale for freezing boar semen. AI Digest 19, 12.
Effect of some zwitterion buffers on the freezing and storage of spermatozoaI bull. E F Graham, B G Crabo, K I Brown, J. Dairy Sci. 55Graham, E.F., B.G. Crabo and K.I. Brown. (1972). Effect of some zwitterion buffers on the freezing and storage of spermatozoaI bull. J. Dairy Sci., 55: 372-378.
Vitamin E against oxidative damage caused by formaldehyde in frontal cortex and hippocampus. Biochemical and histological studies. A Gurel, O Coskun, F Armutcu, M Kanter, O A Ozen, J. Chem. Neuroanat. 29Gurel, A., Coskun, O., Armutcu, F., Kanter, M. and Ozen, O. A. (2005). Vitamin E against oxidative damage caused by formaldehyde in frontal cortex and hippocampus. Biochemical and histological studies. J. Chem. Neuroanat. 29: 173-178.
Cryopreservation of mammalian sperm: what we ask them to survive. R H Hammerstedt, J K Graham, J P Nolan, J Androl. 11Hammerstedt RH, Graham JK, Nolan JP (1990). Cryopreservation of mammalian sperm: what we ask them to survive. J Androl; 11:73-88.
Freezability of semen and fertility of frozen semen packaged in mini and medium French straws: a note. G B Haranath, T B Suryaprakasam, A V N Rao, G Somasekharam, Recent Advances in Buffalo Research. Acharya, R.M., R.R. Lokeshwar and S. Kumar.3Haranath, G.B., T.B. Suryaprakasam, A.V.N. Rao and G. Somasekharam. (1990). Freezability of semen and fertility of frozen semen packaged in mini and medium French straws: a note. In Acharya, R.M., R.R. Lokeshwar and S. Kumar. (eds). Recent Advances in Buffalo Research, 3: 87-88.
Effects of a new antibiotic combination on post-thaw motion characteristics and membrane integrity of buffalo and Sahiwal bull spermatozoa and on the bacteriological quality of their semen. Pak. S Hasan, S M H Andrabi, R Muneer, M Anzar, N Ahmad, Vet. J. 21Hasan, S., S.M.H. Andrabi, R. Muneer, M. Anzar and N. Ahmad. (2001). Effects of a new antibiotic combination on post-thaw motion characteristics and membrane integrity of buffalo and Sahiwal bull spermatozoa and on the bacteriological quality of their semen. Pak. Vet. J., 21: 6-12.
Fundamental aspects of sperm cryobiology: the importance of species and individual differences. W V Holt, Theriogenology. 53Holt WV, (2000a). Fundamental aspects of sperm cryobiology: the importance of species and individual differences. Theriogenology 53, 47-58.
Basic aspects of frozen storage of semen. W V Holt, Anim Reprod Sci. 62Holt WV, (2000b). Basic aspects of frozen storage of semen. Anim Reprod Sci 62, 3-22.
Basic aspects of frozen storage semen. W V Holt, Anim. Reprod. Sci. 62Holt, W.V. (2000). Basic aspects of frozen storage semen. Anim. Reprod. Sci., 62: 3-22.
. A Ijaz, A Hussain, M Aleem, M S Yousaf, H Rehman, Theriogenology. Nili-Ravi buffalo71Bubalus bubalisIjaz, A., A. Hussain, M. Aleem, M.S. Yousaf and H. Rehman. (2009). of Nili-Ravi buffalo (Bubalus bubalis). Theriogenology, 71: 1326-1329.
The lipids of buffalo spermatozoa and seminal plasma. Y C Jain, S R Anand, J Reprod Fert. 47Jain YC, Anand SR, (1976). The lipids of buffalo spermatozoa and seminal plasma. J Reprod Fert 47, 255-260.
Effect of level of glycerol, rates of freezing and thawing on the survival of buffalo spermatozoa in straws. M R Jainudeen, S Das, Proceedings of Asian-Australian Anim Sci Cong. Jainudeen MR, Omar ARAsian-Australian Anim Sci CongSerdang, Malaysia; Kuala Lumpur, MalaysiaPenerbit UniversityJainudeen MR, Das S, (1982). Effect of level of glycerol, rates of freezing and thawing on the survival of buffalo spermatozoa in straws. In: Jainudeen MR, Omar AR (eds), Proceedings of Asian-Australian Anim Sci Cong, Serdang, Malaysia. Penerbit University, Kuala Lumpur, Malaysia, pp. 409-411.
Radical solutions and cultural problems: could free oxygen radicals be responsible for the impaired development of preimplantation mammalian embryos in vitro?. M H Johnson, M H Nasr-Esfahani, Bioessays. 16Johnson MH, Nasr-Esfahani MH, (1994). Radical solutions and cultural problems: could free oxygen radicals be responsible for the impaired development of preimplantation mammalian embryos in vitro? Bioessays 16, 31-38.
Storage of boar semen. L A Johnson, K F Weitze, P Fiser, W M C Maxwell, Anim. Reprod. Sci. 62Johnson, L.A., Weitze, K.F., Fiser, P., Maxwell, W.M.C., (2000). Storage of boar semen. Anim. Reprod. Sci. 62, 143-172.
Lipid peroxidation, mitochondrial membrane potential and DNA integrity of spermatozoa in relation to intracellular reactive oxygen species in liquid and frozen-thawed buffalo semen. G Kadirvel, K Satish, A Kumaresan, Anim. Reprod. Sci. 114Kadirvel, G., Satish, K. and Kumaresan, A. (2009). Lipid peroxidation, mitochondrial membrane potential and DNA integrity of spermatozoa in relation to intracellular reactive oxygen species in liquid and frozen-thawed buffalo semen. Anim. Reprod. Sci. 114: 125-134.
S S Kakar, S R Anand, Changes in adenosine 5¢-triphosphate. Kakar SS, Anand SR, (1981). Changes in adenosine 5¢-triphosphate,
Buffers of constant ionic strength for studying pH-dependent processes. J E Keith, J F Morrison, Methods Enzymol. 87Keith JE, Morrison JF, (1981). Buffers of constant ionic strength for studying pH-dependent processes. Methods Enzymol 87, 405-426.
Effects of osmotic pressure on motility, plasma membrane integrity and viability in fresh and frozen-thawed buffalo spermatozoa. M I R Khan, A Ijaz, Animal. 2Khan, M.I.R. and A. Ijaz. (2008). Effects of osmotic pressure on motility, plasma membrane integrity and viability in fresh and frozen-thawed buffalo spermatozoa. Animal, 2: 548-553.
Effect of vitamins A, D, E on the motility and acrosomal integrity of cryopreserved buffalo bulls" spermatozoa. S I Kolev, Proceedings of 5th World Buffalo Cong. Borghese A, Failla S, Barile VL5th World Buffalo CongCaserta, Italy; Roma, ItalyKolev SI, (1997). Effect of vitamins A, D, E on the motility and acrosomal integrity of cryopreserved buffalo bulls" spermatozoa. In: Borghese A, Failla S, Barile VL (eds), Proceedings of 5th World Buffalo Cong., Caserta, Italy. International Buffalo Federation, Roma, Italy, pp. 833-835.
Effect of different levels of glycerol and yolk on freezing and storage of buffalo semen in milk, Tris and sodium citrate buffers. S Kumar, K L Sahni, G Mohan, Buffalo J. 8Kumar S, Sahni KL, Mohan G, (1992). Effect of different levels of glycerol and yolk on freezing and storage of buffalo semen in milk, Tris and sodium citrate buffers. Buffalo J 8, 151-156.
. S Kumar, K L Sahni, G Mohan, Kumar S, Sahni KL, Mohan G, (1994
. Indian J Anim Sci. 64Indian J Anim Sci 64, 362-364.
Freeze-thaw induced genotoxicity in buffalo (Bubalus bubalis) spermatozoa in relation to total antioxidant status. R Kumar, G Jagan, Mohanarao Arvind, S K Atreja, Mol. Boil. Rep. 38Kumar, R., Jagan, G., Mohanarao Arvind and Atreja, S. K. (2011). Freeze-thaw induced genotoxicity in buffalo (Bubalus bubalis) spermatozoa in relation to total antioxidant status. Mol. Boil. Rep. 38: 1499-1506.
Effect of different levels of glycerol and yolk on freezing and storage of buffalo semen in milk, tris and sodium citrate buffers. S Kumar, K L Sahni, G Mohan, Buffalo J. 2Kumar, S., K.L. Sahni and G. Mohan. (1992). Effect of different levels of glycerol and yolk on freezing and storage of buffalo semen in milk, tris and sodium citrate buffers. Buffalo J., 2: 151-156.
Modulation of post-thaw sperm functions with oviductal proteins in buffaloes. A Kumaresan, M R Ansari, G Abhishek, Anim Reprod Sci. 90Kumaresan A, Ansari MR, Abhishek G, (2005). Modulation of post-thaw sperm functions with oviductal proteins in buffaloes. Anim Reprod Sci 90, 73-84.
Effect of oviductal proteins on sperm functions and lipid perox-idation levels during cryopreservation in buffaloes. A Kumaresan, M R Ansari, A Garg, M Kataria, Kumaresan A, Ansari MR, Garg A, Kataria M, (2006). Effect of oviductal proteins on sperm functions and lipid perox-idation levels during cryopreservation in buffaloes.
. Anim Reprod Sci. 93Anim Reprod Sci 93, 246-257.
Effects of dextrans on cryopreservation of goat caudaepididymal spermatozoa using a chemically defined medium. C N Kundu, J Chakraborty, P Dutta, D Bhattacharyya, A Ghosh, G C Majumder, Reproduction. 123Kundu, C.N., J. Chakraborty, P. Dutta, D. Bhattacharyya, A. Ghosh and G.C. Majumder. (2002). Effects of dextrans on cryopreservation of goat caudaepididymal spermatozoa using a chemically defined medium. Reproduction, 123: 907-913.
Use of powdered egg yolk vs fresh egg yolk for the cryopreservation of ovine semen. F Marco-Jimenez, S Puchades, E Moce, M P Viudesde-Cartro, J S Vicente, M Rodriguez, Reprod Domest Anim. 39Marco-Jimenez F, Puchades S, Moce E, Viudes- de-Cartro MP, Vicente JS, Rodriguez M, (2004). Use of powdered egg yolk vs fresh egg yolk for the cryopreservation of ovine semen. Reprod Domest Anim 39, 438-441.
Revivability of buffalo spermatozoa after deep freezing the semen using various extenders. J S Matharoo, M Singh, Zbl. Vet. Med. A. 27Matharoo, J.S. and M. Singh. (1980). Revivability of buffalo spermatozoa after deep freezing the semen using various extenders. Zbl. Vet. Med. A., 27: 385-391.
The role of intracellular freezing in the death of cells cooled at supraoptimal rates. P Mazur, Cryobiology. 14Mazur, P. (1977). The role of intracellular freezing in the death of cells cooled at supraoptimal rates. Cryobiology, 14: 251- 272.
Freezing of living cells: Mechanisms and implications. P Mazur, Am. J. Physiol. 247Mazur, P. (1984). Freezing of living cells: Mechanisms and implications. Am. J. Physiol., 247: C125-142.
A two-factor hypothesis of freezing injury. P Mazur, S P Liebo, E H Y Chu, Exp. Cell Res. 71Mazur, P., S.P. Liebo and E.H.Y. Chu. (1972). A two-factor hypothesis of freezing injury. Exp. Cell Res., 71: 345-355.
Current status of sperm cryopreservation: why is it better. Cmo Medeiros, F Forell, Atd Oliveira, J L Rodrigues, Theriogenology. 57Medeiros CMO, Forell F, Oliveira ATD, Rodrigues JL, (2002). Current status of sperm cryopreservation: why is it better. Theriogenology 57, 327-344.
Effect of monosaccharides and disaccharides in Tris-based diluents on motility, acrosome integrity and fertility of pellet frozen ram spermatozoa. F C Molinia, G Evans, P I Casares, Wmc Maxwell, Anim Reprod Sci. 36Molinia FC, Evans G, Casares PI, Maxwell WMC, (1994). Effect of monosaccharides and disaccharides in Tris-based diluents on motility, acrosome integrity and fertility of pellet frozen ram spermatozoa. Anim Reprod Sci 36, 113-122.
Update on semen technologies for animal breeding. J M Morrell, Reprod Domest Anim. 41Morrell JM, (2006). Update on semen technologies for animal breeding. Reprod Domest Anim 41, 63-67.
Cryogenic changes in seminal protein of cattle and buffalo. S K Muer, S B Roy, G Mohan, R L Dhoble, Theriogenology. 30Muer SK, Roy SB, Mohan G, Dhoble RL, (1988). Cryogenic changes in seminal protein of cattle and buffalo. Theriogenology 30, 1005-1010.
Cryopreservation of buffalo (Bubalus bubalis) semenlimitations and expectations. D W Mughal, A Ijaz, M S Yousaf, F Wadood, F M Umer, Buffalo Bulettin. 361Mughal, D. W., Ijaz, A., Yousaf, M. S., Wadood, F. & Umer, F. M. (2017). Cryopreservation of buffalo (Bubalus bubalis) semen- limitations and expectations. Buffalo Bulettin, 36(1), 1-14.
Assessment of optimal osmotic pressure of citrate egg yolk extender for cryopreservation of buffalo bull (Bubalus bubalis) semen. D H Mughal, A Ijaz, M S Yousaf, H Rehman, M Aleem, H Zaneb, F Wadood, J. Anim. Plant Sci. 234Mughal, D.H., A. Ijaz, M.S. Yousaf, H. Rehman, M. Aleem, H. Zaneb and F. Wadood. (2013). Assessment of optimal osmotic pressure of citrate egg yolk extender for cryopreservation of buffalo bull (Bubalus bubalis) semen, J. Anim. Plant Sci., 23(4): 964-968.
Deep freezing bull semen in concentrated pellet form. II. Protective action of sugars. H Nagase, T Niwa, S Yamashita, S Irie, Proceedings of 5th International Congress on Animal reproduction and artificial insemination. 5th International Congress on Animal reproduction and artificial inseminationTrento, Italy2Nagase, H., T. Niwa, S. Yamashita and S. Irie. (1964). Deep freezing bull semen in concentrated pellet form. II. Protective action of sugars. In Proceedings of 5th International Congress on Animal reproduction and artificial insemination, Trento, Italy. 2: 1111-1113.
A comparative study on lipid peroxidation, activities of antioxidant enzymes and viability of cattle and buffalo bull spermatozoa during storage at refrigeration temperature. S J Nair, A S Brar, C S Ahuja, S P Sangha, K C Chaudhary, Anim. Reprod. Sci. 96Nair, S. J., Brar, A. S., Ahuja, C. S., Sangha, S. P. and Chaudhary, K. C. (2006). A comparative study on lipid peroxidation, activities of antioxidant enzymes and viability of cattle and buffalo bull spermatozoa during storage at refrigeration temperature. Anim. Reprod. Sci. 96: 21-29.
Performances motility in cooled and freeze thawed B. bubalis spermatozoa at different osmotic pressures. Mjf Nastri, Del Sorbo, C Fabbrocini, A Fasano, G Sansone, G , Proceeding of 7th Int. Symp. Spermatology. Bradley M, Cummins JMeeding of 7th Int. Symp. SpermatologyCairns, Australia; Victoria, AustraliaNastri MJF, Del Sorbo C, Fabbrocini A, Fasano G, Sansone G, (1994). Performances motility in cooled and freeze thawed B. bubalis spermatozoa at different osmotic pressures. In: Bradley M, Cummins JM (eds), Proceeding of 7th Int. Symp. Spermatology, Cairns, Australia. Australian Society of Reproductive Biology, Victoria, Australia, pp. 99-100.
. E E Noiles, P Mazur, P F Watson, F W Kleinhans, J K Critser, Noiles, E.E., P. Mazur, P.F. Watson, F.W. Kleinhans and J.K. Critser. (1993).
Influence of trehalose, taurine, cysteamine and hyaluronan on ram semen. Microscopic and oxidative stress parameters after freeze-thawing process. M Numanbucak, A Atessahin, O Varisli, A Yuce, N Tekin, A Akcay, Theriogenology. 485Biol. Reprod.Biol. Reprod., 48: 99- 109. Numanbucak, M., Atessahin, A., Varisli, O., Yuce, A., Tekin, N. and Akcay, A. (2007). Influence of trehalose, taurine, cysteamine and hyaluronan on ram semen. Microscopic and oxidative stress parameters after freeze-thawing process. Theriogenology. 67(5): 1060-1067.
Comparison of the effects of glutamine and an amino acid solution on post thawed ram sperm parameters, lipid peroxidation and antioxidant activities. M Numanbucak, P B Tuncer, S Sariozkan, P A Ulutas, Small Ruminant Res. 81Numanbucak, M., Tuncer, P. B., Sariozkan, S. and Ulutas, P. A. (2009). Comparison of the effects of glutamine and an amino acid solution on post thawed ram sperm parameters, lipid peroxidation and antioxidant activities. Small Ruminant Res. 81: 13-17.
Prelimanary study on different mediums for deep freezing of buffalo semen. E Oba, E J Fuck, S D Bicudo, F O Pap, O M Ohashi, Proceedings of 4th World Buffalo Congress. Vale, W.G., V.H. Barnabe and J.C.A.de. Mattos4th World Buffalo CongressSao Paulo; Roma, Italy. Pace MM, Graham EF39J Anim SciOba, E., E.J. Fuck, S.D. Bicudo, F.O. Pap and O.M. Ohashi. (1994). Prelimanary study on different mediums for deep freezing of buffalo semen, p. 579-581. In Vale, W.G., V.H. Barnabe and J.C.A.de. Mattos (eds.) Proceedings of 4th World Buffalo Congress, Sao Paulo, Brazil. International Buffalo Federation, Roma, Italy. Pace MM, Graham EF, (1974). Components in egg yolk which protect bovine spermatozoa during freezing. J Anim Sci 39, 1144-1149.
Present situation and future perspective of buffalo production in Asia. T N Pasha, Z Hayat, J. Anim. Plant Sci. 22Pasha, T. N. and Hayat, Z. (2012). Present situation and future perspective of buffalo production in Asia. J. Anim. Plant Sci. 22: 250-256.
Effect of different egg yolk level on cryopreservation capabilities of jakhrana goat semen. R Priyadharsini, S K Jindal, D Sharma, N Ramachandran, S D Kharche, A K Goel, J. Ani. Sci. Adv. 1Priyadharsini, R., Jindal, S.K., Sharma, D., Ramachandran, N., Kharche, S.D. and Goel, A.K. (2011). Effect of different egg yolk level on cryopreservation capabilities of jakhrana goat semen. J. Ani. Sci. Adv. 1: 28-37.
A review on goat sperm cryopreservation. P H Purdy, Small Rum. Res. 6Purdy, P.H. (2006). A review on goat sperm cryopreservation. Small Rum. Res., 6: 215- 225.
A comparative study of freezing buffalo semen in two dilutors. B C Raizada, A Sattar, M D Pandey, Proceedings of 2nd World Buffalo Cong. Acharya RM, Lokeshwar RR, Kumar AT2nd World Buffalo CongNew Delhi, India; Roma, ItalyRaizada BC, Sattar A, Pandey MD, (1990). A comparative study of freezing buffalo semen in two dilutors. In: Acharya RM, Lokeshwar RR, Kumar AT (eds), Proceedings of 2nd World Buffalo Cong, New Delhi, India. International Buffalo Federation, Roma, Italy, pp. 66-74.
Effect of glycerol level and cooling rate on post-thaw semen quality of Malaysian swamp buffalo. P Ramakrishnan, M O Ariff, W G Vale, V H Barnabe, Jca Mattos, De, Proceedings of 4th World Buffalo Cong. 4th World Buffalo CongSao Paulo; Roma, ItalyRamakrishnan P, Ariff MO, (1994). Effect of glycerol level and cooling rate on post-thaw semen quality of Malaysian swamp buffalo. In: Vale WG, Barnabe VH, Mattos JCA de, Proceedings of 4th World Buffalo Cong, Sao Paulo, Brazil. International Buffalo Federation, Roma, Italy, pp. 540-542.
Effect of thaw rates on motility, survival and acrosomal integrity of buffalo spermatozoa frozen in medium French straws. Avn Rao, G B Haranath, G S Sekharam, J R Rao, Anim Reprod Sci. 12Rao AVN, Haranath GB, Sekharam GS, Rao JR, (1986). Effect of thaw rates on motility, survival and acrosomal integrity of buffalo spermatozoa frozen in medium French straws. Anim Reprod Sci 12, 123-129.
Antagonist effect of DMSO on the cryoprotection ability of glycerol during cryopreser-vation of buffalo sperm. Z Rasul, N Ahmed, M Anzar, Theriogenology. 68Rasul Z, Ahmed N, Anzar M, (2007). Antagonist effect of DMSO on the cryoprotection ability of glycerol during cryopreser-vation of buffalo sperm. Theriogenology. 68, 813- 819.
Effect of buffering systems on post-thaw motion characteristics, plasma membrane integrity, and acrosome morphology of buffalo spermatozoa. Z Rasul, M Anzar, S Jalali, N Ahmad, Anim Reprod Sci. 59Rasul Z, Anzar M, Jalali S, Ahmad N, (2000). Effect of buffering systems on post-thaw motion characteristics, plasma membrane integrity, and acrosome morphology of buffalo spermatozoa. Anim Reprod Sci 59, 31-41.
Changes in motion characteristics, plasma membrane integrity and acrosome morphology during cryopreservation of buffalo spermatozoa. Z Rasul, N Ahmed, M Anzar, J. Androl. 222Rasul, Z., Ahmed, N. and Anzar, M. (2001). Changes in motion characteristics, plasma membrane integrity and acrosome morphology during cryopreservation of buffalo spermatozoa. J. Androl. 22(2): 278- 283.
Ways to improve the biosecurity of bovine semen. L Ruigh, J C Bosch, M C Brus, B Landman, J S Merton, Reprod. Dom. Anim. 41Ruigh, L., Bosch, J.C., Brus, M.C., Landman, B., Merton, J.S., (2006). Ways to improve the biosecurity of bovine semen. Reprod. Dom. Anim. 41, 268-274.
Semen quality: importance of and influencing factors. R G Saacke, Proceedings of 10th NAAB Tech. Conf. A. I. Reprod. 10th NAAB Tech. Conf. A. I. ReprodMilwaukee, WI, USA; Columbia, USASaacke RG, (1984). Semen quality: importance of and influencing factors. In: Proceedings of 10th NAAB Tech. Conf. A. I. Reprod Milwaukee, WI, USA. National Association of Animal Breeders, Columbia, USA, pp. 30-36.
Yolk as a cryoprotectant in deep-freezing of bovine semen. K L Sahni, G Mohan, Indian J. Anim. Sci. 60Sahni, K.L. and G. Mohan. (1990). Yolk as a cryoprotectant in deep-freezing of bovine semen. Indian J. Anim. Sci., 60: 828-829.
Storage of ram semen. S Salamon, Wmc Maxwell, Anim Reprod Sci. 62Salamon S, Maxwell WMC, (2000). Storage of ram semen. Anim Reprod Sci 62, 77-111.
Storage of buffalo (Bubalus bubalis) semen. G Sansone, M J F Nastri, A Fabbrocini, Anim. Reprod. Sci. 62Sansone, G., M.J.F. Nastri and A. Fabbrocini. (2000). Storage of buffalo (Bubalus bubalis) semen. Anim. Reprod. Sci., 62: 55- 76.
A deep uterotubal. E M Senatore, S Verberckmoes, M Pascale, G A Presicce, Senatore EM, Verberckmoes S, Pascale M, Presicce GA, (2004). A deep uterotubal
The eect of egg yolk level and dose rate of semen diluted in caprogen. P Shannon, Proceedings of 7th Int. 7th IntMilan, ItalyShannon P, (1972). The eect of egg yolk level and dose rate of semen diluted in caprogen. Proceedings of 7th Int. Cong. Anim. Reprod. A.I. Munich, Germany. International Congress on Animal Reproduction and Artificial Insemination, Milan, Italy, pp. 1440-1442.
Effect of egg yolk levels on the fertility of diluted bovine sperm stored at ambient temperatures. N. P Shannon, B Curson, Z. J. Agric. Res. 26Shannon, P., Curson, B., (1983). Effect of egg yolk levels on the fertility of diluted bovine sperm stored at ambient temperatures. N. Z. J. Agric. Res. 26, 187-189.
Effect of Bradykinin on Murrah buffalo (Bubalus bubalis) semen cryopreservation. M K Shukla, A K Misra, Anim Reprod Sci. 97Shukla MK, Misra AK, (2007). Effect of Bradykinin on Murrah buffalo (Bubalus bubalis) semen cryopreservation. Anim Reprod Sci 97, 175-179.
Male infertility nutritional and environmental considerations. S Sinclair, Altern. Med. Rev. 5Sinclair, S. (2000). Male infertility nutritional and environmental considerations. Altern. Med. Rev. 5: 28-38.
Effect of vitamin C addition in the diluent on the quality of deep frozen Murrah buffalo bull (Bubalus bubalis) semen. B Singh, D Chand, P Singh, N K Yadav, Int J Anim Sci. 11Singh B, Chand D, Singh P, Yadav NK, (1996). Effect of vitamin C addition in the diluent on the quality of deep frozen Murrah buffalo bull (Bubalus bubalis) semen. Int J Anim Sci 11, 131-132.
Studies on lactic dehydrogenase and sorbitol dehydrogenase release in relation to deep freezing of bualo semen in certain extenders. J Singh, G R Pangawkar, R K Biswas, A K Srivastava, R D Sharma, Theriogenology. 34Singh J, Pangawkar GR, Biswas RK, Srivastava AK, Sharma RD, (1990). Studies on lactic dehydrogenase and sorbitol dehydrogenase release in relation to deep freezing of bualo semen in certain extenders. Theriogenology 34, 371-378.
Effect of post thaw incubation on semen quality of buffalo bulls comparison with cattle. M Singh, H C Pant, Buffalo Bull. 19Singh M, Pant HC, (2000). Effect of post thaw incubation on semen quality of buffalo bulls comparison with cattle. Buffalo Bull 19, 51-54.
Initial stage glycerolization prevents the incidence of backward sperm motility during cryopreservation and increases buffalo semen freezability. P Singh, I Singh, S Singh, R K Sharma, Indian J Anim Sci. 76Singh P, Singh I, Singh S, Sharma RK, (2006). Initial stage glycerolization prevents the incidence of backward sperm motility during cryopreservation and increases buffalo semen freezability. Indian J Anim Sci 76, 777-779.
Effect of dierent level of egg yolk on freezability of bualo semen. P Singh, S Singh, O K Hooda, Haryana Vet. 38Singh P, Singh S, Hooda OK, (1999). Effect of dierent level of egg yolk on freezability of bualo semen. Haryana Vet 38, 26-28.
Studies on buffalo sperm morphology during various stages of freezing in certain extenders. J Singh, G R Pangawkar, R K Biswas, N Kumar, Indian J. Anim. Sci. 12Singh, J., G.R. Pangawkar, R.K. Biswas and N. Kumar. (1991). Studies on buffalo sperm morphology during various stages of freezing in certain extenders. Indian J. Anim. Sci., 12: 126-129.
Effect of cysteine fortification on cryopreservation of buffalo semen in milk whey extenders. N P Singh, R S Manik, V S Raina, Theriogenology. 32Singh, N.P., R.S. Manik and V.S. Raina, (1989). Effect of cysteine fortification on cryopreservation of buffalo semen in milk whey extenders. Theriogenology, 32: 979- 986.
Freezability of buffalo bull semen using different extenders. P Singh, J K Jindal, S Singh, O K Hooda, Indian J. Anim. Reprod. 21Singh, P., J.K. Jindal, S. Singh and O.K. Hooda. (2000). Freezability of buffalo bull semen using different extenders. Indian J. Anim. Reprod., 21: 41-42.
Dimethyl sulfoxide as a cryoprotective agent for freezing bovine semen. W H Snedeker, W S Gaunya, J Anim Sci. 30Snedeker WH, Gaunya WS (1970). Dimethyl sulfoxide as a cryoprotective agent for freezing bovine semen. J Anim Sci 30:953- 956.
A comparative study on lipid peroxidation, activities of antioxidant enzymesand viability of cattle and buffalo bull spermatozoa during storage at refrigeration temperature. J N Sreejith, A S Brar, C S Ahuja, S P S Sangha, K C Chaudhary, Anim. Reprod. Sci. 96Sreejith, J. N., Brar, A. S., Ahuja, C. S., Sangha, S. P. S. and Chaudhary, K. C. (2006). A comparative study on lipid peroxidation, activities of antioxidant enzymesand viability of cattle and buffalo bull spermatozoa during storage at refrigeration temperature. Anim. Reprod. Sci. 96: 21-29.
Effects of cooling and warming conditions on post-thawed motility and fertility of cryopreserved buffalo spermatozoa. P Sukhato, S Thongsodseang, A Utha, N Songsasen, Anim Reprod Sci. 67Sukhato P, Thongsodseang S, Utha A, Songsasen N, (2001). Effects of cooling and warming conditions on post-thawed motility and fertility of cryopreserved buffalo spermatozoa. Anim Reprod Sci 67, 69-77.
Effects of different prefreezing rates on buffalo sperm motility and ultrastructure preservation. R Talevi, S Pelosi, G Sansone, F Grasso, D Matassino, Proceedings of 4th International. 4th InternationalBuffalo Congress, Sao Paulo, Brazil3Talevi, R., S. Pelosi, G. Sansone, F. Grasso and D. Matassino. (1994). Effects of different pre- freezing rates on buffalo sperm motility and ultrastructure preservation. In Proceedings of 4th International Buffalo Congress, Sao Paulo, Brazil. 3: 537-539.
Increasing Buffalo Production. B Tatham, Tatham B, (2000). Increasing Buffalo Production;
. Using Reproduction Technology. Report Rur. Indust. Res Corp. Dev. Using Reproduction Technology. Report Rur. Indust. Res Corp. Dev., Kingston, ACT, Australia.
Hygienic aspects of storage and use of semen for artificial insemination. M Thibier, B Guerin, Anim. Reprod. Sci. 62Thibier, M. and B. Guerin. (2000). Hygienic aspects of storage and use of semen for artificial insemination. Anim. Reprod. Sci., 62: 233-251.
Metabolism of spermatozoa. The formation and elimination of hydrogen peroxide by spermatozoa and eects on motility and survival. J Tosic, A Walton, Biochem J. 47Tosic J, Walton A, (1950). Metabolism of spermatozoa. The formation and elimination of hydrogen peroxide by spermatozoa and eects on motility and survival. Biochem J 47, 199-212.
Effect of different equilibration times and extenders on deep freezing of buffalo semen. R K Tuli, M Singh, J S Matharoo, Theriogenology. 16Tuli, R.K., Singh, M., Matharoo, J.S., (1981). Effect of different equilibration times and extenders on deep freezing of buffalo semen. Theriogenology 16, 99-104.
Semen freezing and artificial insemination in water buffalo in the amazon valley. W G Vale, O M Ohashi, H F L Ribeiro, J S Sousa, Buffalo J. 2Vale, W.G., O.M. Ohashi, H.F.L. Ribeiro and J.S. Sousa. (1991). Semen freezing and artificial insemination in water buffalo in the amazon valley. Buffalo J., 2: 137-144.
The causes of reduced fertility with cryopreserved semen. P F Watson, Anim Reprod Sci. 60Watson PF, (2000). The causes of reduced fertility with cryopreserved semen. Anim Reprod Sci 60 61, 481-482.
A comparison of critical osmolality and hydraulic conductivity and its activation energy in fowl and bull spermatozoa. P F Watson, E Kunze, P Cramer, R H Hammerstedt, Watson PF, Kunze E, Cramer P, Hammerstedt RH, (1992). A comparison of critical osmolality and hydraulic conductivity and its activation energy in fowl and bull spermatozoa.
Recent developments and concepts in the cryopreservation of spermatozoa and the assessment of their post-thawing function. P F Watson, Reprod. Fertil. Dev. 7Watson, P. F. (1995). Recent developments and concepts in the cryopreservation of spermatozoa and the assessment of their post-thawing function. Reprod. Fertil. Dev. 7: 871-91.
Effects of egg yolk, glycerol and the freezing rate on the viability and acrosomal structures of frozen ram spermatozoa. P F Watson, I C A Martin, Australian journal of biological sciences. 282Watson, P. F., & Martin, I. C. A. (1975). Effects of egg yolk, glycerol and the freezing rate on the viability and acrosomal structures of frozen ram spermatozoa. Australian journal of biological sciences, 28(2), 153-160.
Effects of trehalose, and sucrose, osmolality of the freezing medium, and cooling rate on viability and intactness of bull sperm after freezing and thawing. H Woelders, A Mathiijs, B Engel, Cryobiology. 35Woelders, H., A. Mathiijs and B. Engel. (1997). Effects of trehalose, and sucrose, osmolality of the freezing medium, and cooling rate on viability and intactness of bull sperm after freezing and thawing. Cryobiology, 35: 93- 105.
Effect of ascorbic acid and vitamin E supplementation on semen quality and biochemical parameters of male rabbits. M I Yousef, G A Abdallah, K I Kcalamel, Anim. Reprod. Sci. 76Yousef, M. I., Abdallah, G. A., and Kcalamel, K. I. (2003). Effect of ascorbic acid and vitamin E supplementation on semen quality and biochemical parameters of male rabbits. Anim. Reprod. Sci. 76: 99-111.
Dimethyl sulphoxide: a review of its applications in cell biology. Z W Yu, P J Quinn, Biosci Rep. 14Yu ZW, Quinn PJ, (1994). Dimethyl sulphoxide: a review of its applications in cell biology. Biosci Rep 14, 259-281.
Cryopreservation of Buffalo Bull Semen-Restriction and Expectation: A Review. Pavan Kumar Mittal, A K Madan, Vijay Sharma, G S Gottam, Barkha Gupta, Pavan Kumar Mittal, A.K. Madan, Vijay Sharma, G.S.Gottam and Barkha Gupta. 2019. Cryopreservation of Buffalo Bull Semen-Restriction and Expectation: A Review.
. 10.20546/ijcmas.2019.801.144Int.J.Curr.Microbiol.App.Sci. 801Int.J.Curr.Microbiol.App.Sci. 8(01): 1351-1368. doi: https://doi.org/10.20546/ijcmas.2019.801.144
| [
-0.11688467860221863,
-0.11276933550834656,
0.003781065344810486,
0.04963675141334534,
-0.004071512259542942,
-0.07124371826648712,
-0.10519386827945709,
0.1744609773159027,
-0.02823321335017681,
0.1592613160610199,
0.006216038949787617,
-0.04792364314198494,
-0.0760614424943924,
0.0492278... |
Балканско научно обозрение
2019
Samara State Social-Pedagogical University
65/67443099Samara, street GorjkogoRussia
Балканско научно обозрение
46201910.34671/SCH.BSR.2019.0304.001571 психологически науки UDC 159.9.075
ВВЕДЕНИЕ В настоящее время проблема выживания человечества обострена до предела. Предела, за которым человечества может и не быть. Одним из средств, способных обеспечить возможность существования мира человека, по мнению многих ученых, является толерантность. Феномен этого понятия определяется его многозначностью и не ограничивается только содержанием прямого перевода с латинского языка слова Tolerantia, которое обозначает терпение, терпеливость, принятие.
Гуманитарный смысл этого феномена намного шире. Диапазон этого понятия распространяется от представлений о толерантности как механизме эволюции человека, как системе его взаимоотношений с обществом, природой, до аутотолерантности, связанной с рефлексивностью сознания и являющейся механизмом внутреннего диалога Я с Другим. Подход к толерантности у большинства ученых и практиков в области гуманитарных дисциплин связан с готовностью человека взаимодействовать с другим человеком, с готовностью принимать его и других людей такими, какие они есть до той степени, пока оно (принятие) не ограничивает его собственную свободу. Если происходит ограничение свободы, то необходимо обеспечение правовых процессов, в которых определяются принципы взаимодействия двух сторон.
Толерантность, определяя содержание межличностных человеческих отношений, проявляет себя в форме толерантных отношений. Толерантность -«это форма отношения к иному, к отличающемуся, к разнообразному» [5,с.4]. Толерантные отношения между субъектами общения являются предметом исследования многих других ученых (Н.А. Асташовой, И.В. Абакумовой, Л.В. Байбородовой, Е.В. Баскаковой, С.К. Бондыревой, Е.О. Галицких, И.Б. Гриншпуна, П.Н. Ермакова, Е.Ю. Клепцовой, Г.С. Кожухаря, Д.В. Колесова и др.). Методологическое значение этих исследований состоит в том, что они значительно расширяют область изучения понятия «толерантные отношения», в частности, в образовательной сфере.
В настоящее время перед семьей и школой со всей очевидностью стоит важная воспитательная задача, связанная с формированием и развитием у детей и подростков толерантного отношения к другому человеку. Думается, что система «Ученик -учитель» является тем вариантом системы, в которой возможно оптимальное создание условий для развития толерантности у подрастающего поколения. Наиболее актуальна данная проблема для подростков, так как отрочество является важнейшим периодом, когда изменяются позиции и установки по отношению к взрослым. Тем более, что именно у подростков 13-14-ти лет психологи отмечают снижение авторитета учителя и уменьшение степени доверия к ним.
С нашей точки зрения, анализировать толерантные отношения подростков к учителю целесообразно через его отдельные компоненты: когнитивный, эмоциональный и поведенческий. Когнитивный, познавательный компонент толерантного отношения ученика к учителю включает познание другого человека (в нашем случае, учителя) и познание себя, анализ психолого-педагогических ситуаций, продумывание стратегии и тактики поведения и прогноз предполагаемых препятствий. Изучение поведенческого компонента толерантного отношения подростка к учителю позволяет понять, как подросток проявляет свое отношение к учителю, какие осуществляет действия, выражающие отношение к учителю, и какие способы поведения в ситуациях взаимодействия с учителем он выбирает. Изучение эмоционального компонента толерантного отношения подростка к учителю обеспечивает аналитическое опознание и обозначение испытываемых им к учителю эмоций и чувств. Содержание эмоционального компонента толерантно-го отношения ученика к учителю составляет внутреннее эмоциональное расположение к учителю, диапазон которого распространяется от эмоциональной отзывчивости, симпатии, радости и открытости в общении с учителем до эмоций и чувств, основанных на неприятных субъективных переживаниях -разочаровании, презрении, неприязни, антипатии, злости.
МЕТОДОЛОГИЯ Цель исследования: определение психологических условий развития эмоционального компонента толерантного отношения подростков к учителям.
Объект исследования: отношение подростков к учителям.
Предмет исследования: особенности развития эмоционального компонента толерантного отношения подростков к учителям.
Для достижения поставленной цели были определены следующие задачи научного исследования: 1) провести теоретический анализ научных подходов зарубежной и отечественной психологии к проблеме толерантности подростков по отношению к учителям и уточнить содержательные характеристики эмоционального компонента толерантного отношения;
2) определить характерологические свойства подростков экспериментальной и контрольной групп;
3) изучить особенности составляющих эмоционального компонента толерантного отношения подростков к учителям -доверия, доброжелательности, эмпатии и тревожности; 4) разработать и апробировать программу, направленную на развитие эмоционального компонента толерантного отношения учителям у подростков с характерологическими свойствами разных социально-психологических типов личности (далее -СПТЛ); 5) определить особенности развития составляющих эмоционального компонента толерантного отношения к учителям (доверия, доброжелательности, эмпатии в межличностных отношениях, тревожности) у подростков с характерологическими свойствами разных СПТЛ.
Для решения поставленных задач использовались диагностические методы, формирующий эксперимент и методы математической статистики.
В эксперименте приняли участие 98 школьников подросткового возраста. По своему качественному и количественному составу экспериментальная и контрольная группы учеников были равнозначными.
Эмпирическая часть исследования реализовалась в ходе организационного, констатирующего, формирующего и контрольного этапов. В ходе организационного этапа устанавливался контакт с испытуемыми и был подобран комплекс диагностических методик, позволяющих изучать эмоциональный компонент толерантного отношения школьников к учителям.
Диагностирование осуществлялось в ходе констатирующего и контрольного этапов эксперимента по методикам: «Диагностика социально-психологического типа личности подростков» (автор В.М. Минияров [6] На формирующем этапе эксперимента подростки из экспериментальной группы приняли участие в реализации психологической развивающей программы, направ-relationship, anxiety during an interaction with a teacher. психологически науки ленной на развитие толерантного отношения к учителям и состоящей из двух разделов -практического (социально-психологический тренинг) и консультационного (индивидуальное психологическое консультирование участников эксперимента). Программа социально-психологического тренинга предусматривала проведение 20 занятий. Тренинговые занятия проводились в течение 10-ти недель в семи группах подростков. Целью социально-психологического тренинга явилось совершенствование межличностных отношений школьников подросткового возраста и учителей за счет развития у подростков личностных качеств, обеспечивающих проявление толерантности по отношению к учителю.
В ходе социально-психологического тренинга были реализованы такие методы и приемы, которые эффективно развивали у подростков доверие, доброжелательность, эмпатию, эмоционально-ценностное отношение к себе и другим людям и формировали у них умения и навыки саморегуляции в ситуации взаимодействия с учителем. Методологической основой программы явились теоретические положения и практические результаты, полученные в исследованиях Н.М. Гаджиевой, Н.В. Кислинской, А.Г. Лидерса, Г.А. Цукерман и др.
В течение 10-ти недель (пока реализовалась программа) участники программы имели возможность консультироваться с психологом по проблеме затрудненного общения с учителем.
Методы математической статистики, используемые в эмпирической части исследования: определение процентного соотношения, метод корреляционного анализа по критерию Пирсона, метод, устанавливающий t-критерий Стьюдента для зависимых и независимых выборок. Процедура подсчета осуществлялась с помощью программы SPSS.
РЕЗУЛЬТАТЫ В ходе констатирующего этапа эмпирического исследования в экспериментальной группе были выявлены подростки с характерологическими свойствами всех семи отмеченных социально-психологических типов личности (СПТЛ) -гармоничного (17%), сензитивного (17%) и конформного (9%), тревожного (19%), доминирующего (12%), инфантильного (14%) и интровертивного (10%). Контрольная группа по количеству подростков с определенным СПТЛ была сформирована подобно экспериментальной группе.
Диагностические результаты, полученные с помощью теста «Шкала доверия» (автор Н. Розенберг), позволяющего устанавливать уровни доверия к другому человеку, свидетельствуют о том, что более половины из группы опрошенных респондентов (67%) не доверяет другим людям. Наиболее многочисленными среди них оказались группы подростков с характерологическими свойствами тревожного (92%), доминирующего (88%) и инфантильного (75%) СПТЛ. И только треть опрошенных учеников (33%) демонстрирует средний уровень доверия. Большинство из них -это подростки со свойствами гармоничного (62%), сензитивного (59%) и конформного (44%) СПТЛ. Ни в одной из групп подростков не были установлены высокие уровни доверия.
Исследование доброжелательности подростков по методике «Шкала доброжелательности» (автор Д.Кэмпбелл, адапт. Ю.А. Менджерицкой) показало, что лишь половина из опрошенных подростков (50%) характеризуется средними показателями по данному параметру. У большинства опрошенных учеников наблюдается средний уровень доброжелательности. Среди них подростки с характерологическими свойствами интровертивного (65%), гармоничного (50%), сензитивного (56%) и инфантильного (53%) СПТЛ. Наиболее интенсивно выраженное отношение доброжелательности установлено лишь у 40% учеников от группы опрашиваемых школьников: у подростков с характерологическими свойствами сензитивного (35%), гармоничного (29%), тревожного (8%) и инфантильного (7%) СПТЛ.
Недоброжелательное отношение к другим людям отмечено у трети респондентов (37%).Среди них подростки с характерологическими свойствами доминирующего (63%), тревожного (42%) и инфантильного (43%) СПТЛ.
Результаты данного исследования показали, что, хотя большинство опрашиваемых подростков доброжелательно относятся к другому человеку, тем не менее, у более трети подростков наблюдается недоброжелательное отношение к другим людям. Можно предположить, что проявляемая недоброжелательность, вероятно, поддерживает интолерантность подростков по отношению к учителям.
Исследование следующей составляющей эмоционального компонента толерантного отношения подростков к учителям -эмпатии -проведено с помощью теста «Диагностика эмпатийных тенденций личности» И.М. Юсупова.
В результате диагностирования было установлено, что большинство опрашиваемых подростков (57%) характеризуется средним уровнем эмпатии в межличностных отношениях.
Этот уровень эмпатии в межличностных отношениях чаще демонстрировали подростки с характерологическими свойствами доминирующего (54%), сензитивного (51%), инфантильного (79%) и тревожного (66%) СПТЛ. Большинство (70%) из группы подростков с характерологическими свойствами гармоничного СПТЛ демонстрируют высокие и очень высокие уровни эмпатии в межличностных отношениях. Кроме того, в этой группе не было выявлено ни одного подростка с низкими уровнями эмпатии. И, наоборот, среди подростков других СПТЛ не обнаружены подростки с высокими уровнями эмпатии в межличностных отношениях, а были выявлены респонденты с низкими и очень низкими уровнями эмпатии в межличностных отношениях.
Полученные результаты исследования подтверждают точку зрения психологов Голубевой Н.А., Дубровиной, И.В., Ивановой Н.М. Марцинковская Т.Д. Пономаревыми Д.И. и Е.А., Чупахиным Н.П.
Данные авторы считают, что в подростковом возрасте наблюдается активное формирование целого комплекса индивидно-личностных качеств и свойств, которые определяют особенности общения подростков [1-3, 7, 11]. Доверие, доброжелательность и эмпатия являются важными характеристиками эмоционального компонента толерантного отношения. Подросток открывается другому человеку искренне, с доверием, с готовностью услышать его, если не нарушена его базовая потребность в безопасности. Если в этих отношениях присутствует страх перед этим другим (в нашем случае, перед учителем), подростку трудно относиться к нему доброжелательно.
Так, с помощью методики Б.Н. Филлипса «Определение уровней школьной тревожности» было установлено, что для большинства подростков (85,7%) характерно наличие повышенных и высоких уровней тревожности и страхов в ситуациях взаимодействия с учителями. Они выявлены у подростков с характерологическими свойствами доминирующего (67%), инфантильного (32%) и тревожного (24%) СПТЛ. Значимость этих данных для работы психолога с подростком связана с тем, что тревожность и страх, испытываемые им в ситуации взаимодействия с учителем, создают основу для интолерантного отношения подростка к учителю, проявляющегося в оскорблении, насмешках, демонстрациях пренебрежения и негативизма. [9] На основании результатов, характеризующих личностные особенности учеников, были определены уровни эмоционального компонента толерантного отношения, проявляемые подростками со свойствами определенных социально-психологических типов личности.
Результаты исследования свидетельствуют о том, что 12% из группы школьников с характерологически-ми свойствами доминирующего СПТЛ, 7% из группы школьников со свойствами инфантильного СПТЛ и 5% -из группы школьников с характерологическими свойствами тревожного СПТЛ характеризуются очень низкими уровнями эмоционального компонента толерантного отношения к учителям.
Среди всех обследованных подростков только у учеников с характерологическими свойствами сензитивного СПТЛ не выявлен низкий (и очень низкий) уровень эмоционального компонента. Наибольшее количество учеников с данным уровнем эмоционального компонента наблюдается среди подростков с характерологическими свойствами конформного (39%), доминирующего (37%) и интровертивного (35%) СПТЛ.
Средний уровень эмоционального компонента выявлен у подростков с характерологическими свойствами всех рассматриваемых СПТЛ. Высокие уровни эмоционального компонента установлены у подростков со свойствами гармоничного (15%) и сензитивного (15%) СПТЛ. Среди подростков этих групп (по 9% соответственно), а также среди подростков со свойствами тревожного СПТЛ (5%) установлены респонденты с очень высоким уровнем эмоционального компонента толерантного отношения к учителям. Подростки с характерологическими свойствами доминирующего, конформного и интровертивного СПТЛ по результатам диагностики не продемонстрировали высокие уровни исследуемого компонента.
Привлечение к диагностическим данным подростков из экспериментальной и контрольной групп на констатирующем этапе эксперимента статистического метода, устанавливающего t-критерий Стьюдента для независимых выборок, показало, что между этими двумя группами нет статистически значимых различий (p>0,05).
Корреляционный анализ, привлеченный к диагностическим результатам констатирующего эксперимента, указывает на наличие прямой зависимости между показателями «доверие» и «доброжелательность» (ri=0,51957, p<0,001); тенденция прямой зависимости определена и в отношении показателей «эмпатия» и «доброжелательность» (ri=0,218072, р<0,1). Установленная тенденция прямой зависимости между показателями «тревожность и страхи в отношениях с учителями» -«доверие» (ri=0,230005, р<0,1), «тревожность и страхи в отношениях с учителями» -«эмпатия» (ri=0,23368, р<0,1) свидетельствует о том, что, чем выше у подростка эмоциональная чувствительность, тем чаще они испытывают чувство тревоги в процессе межличностных отношений с учителями. Обратная корреляционная зависимость, установленная между показателями «доброжелательность» и «тревожность и страхи в отношениях с учителями», свидетельствует о том, что с ростом уровня тревожности и страхов в отношениях с учителем снижается проявление доброжелательности к нему (ri =-0,208, р<0,1).
Повторная диагностика на контрольном этапе эксперимента, проведенная по методикам констатирующего этапа, позволила оценить эффективность реализованной в экспериментальной группе подростков программы и тем самым, охарактеризовать условия развития эмоционального компонента толерантного отношения подростков к учителям.
Сравнительный анализ результатов констатирующего и контрольного этапов эксперимента показал наличие у подростков из экспериментальной группы положительной динамики уровней развития эмоционального компонента толерантного отношения к учителям. Особенно она заметна в группах подростков со свойствами гармоничного, сензитивного, доминирующего, тревожного и интровертивного СПТЛ. У участников программы повысились уровни доверия, доброжелательности и эмпатии; среди них уменьшилось количество подростков, демонстрирующих тревожность и страх в ситуациях взаимодействия с учителями.
), «Шкала доверия» (автор Н. Розенберг, адапт.Ю.А. Менджерицкой [5,с.104-105]), «Шкала доброжелательности» (автор Д. Кэмпбелл, адапт. Ю.А. Менджерицкой [4,с.102-104]), «Диагностика эмпатийных тенденций личности» (автор И.М. Юсупов [12]) и тест «Определение школьной тревожности» (автор Б.Н. Филлипс [8,с.69-77]). Уровень эмоционального компонента структуры толерантного отношения ученика к учителю определялся по специальной таблице, объединившей характеристики доверия, доброжелательности, эмпатии и тревожности, проявляемой в межличностных отношениях с учителями.
psychological science
Забродина Любовь Александровна, Забродина Ольга Владимировна, Мухина Юлдуз Робертовна ЭМОЦИОНАЛЬНО-ЛИЧНОСТНЫЙ КОМПОНЕНТ В СТРУКТУРЕ ... Balkan Scientific Review. 2019. Т.3. № 4(6)
У подростков со свойствами инфантильного и кон-
Забродина Любовь Александровна, Забродина Ольга Владимировна, Мухина Юлдуз Робертовна ЭМОЦИОНАЛЬНО-ЛИЧНОСТНЫЙ КОМПОНЕНТ В СТРУКТУРЕ ...
формного СПТЛ отмечаются незначительные положительные изменения доверия и эмпатии. Необходимо отметить, что подростки со свойствами инфантильного СПТЛ характеризуются равнодушием, беспомощностью, эгоистичностью, нерешительностью (по отношению к людям) и пассивностью и безответственностью (по отношению к деятельности), а подростки со свойствами конформного СПТЛ -хитростью, изворотливостью, нечестностью и желанием понравиться (к людям) и активностью и недобросовестностью (к деятельности). Поэтому, возможно, выявленная незначительная динамика доверия и эмпатии связана как с характерологическими особенностями данных подростков, на которые указывает В.М. Минияров[6], так и с тем, что экспериментальная программа не в полной мере обеспечила данным подросткам эффективные способы развития этих показателей эмоционального компонента толерантного отношения к учителю.Используемый в исследовании метод, направленный на определение t-критерия Стьюдента для зависимых выборок, показал, что только в экспериментальной группе подростков отмечена статистически достоверная динамика доброжелательности (t=4,95, p<0,001), эмпатии (t=3,1718, p<0,001) и доверия (t=2,23, р<0,05). У подростков из контрольной группы установлена только статистически достоверная динамика эмпатии (t=2,01, p<0,05). ВЫВОДЫ 1. Изучение эмоционального компонента толерантного отношения школьников подросткового возраста к учителю имеет высокую научную и практическую значимость.2. Содержательными характеристиками эмоционального компонента толерантного отношения подростков к учителям являются доброжелательность, доверие, эмпатия и тревожность, проявляемая в ситуациях взаимодействия с учителем.3. Корреляционный анализ позволил обнаружить: прямую связь между доверием и доброжелательностью; тенденции прямой зависимости как эмпатии с доброжелательностью, так и этих показателей с тревожностью и страхами подростков в отношениях с учителями; между показателями «тревожность и страхи в отношениях с учителями» и «доброжелательность» установлена обратно пропорциональную зависимость.4. Обнаружены статистически значимые различия в степени сформированности эмоционального компонента толерантного отношения к учителям у подростков с разными характерологическими свойствами СПТЛгармоничного, доминирующего, интровертивного, тревожного, сензитивного, конформного и инфантильного.5. Обнаружена положительная динамика эмоционального компонента толерантного отношения к учителям после участия в экспериментальной программе у подростков с характерологическими свойствами гармоничного, доминирующего, интровертивного, тревожного и сензитивного СПТЛ.Перспективным направлением дальнейшего исследования данной проблемы мы видим в изучении специфики формирования и динамики развития эмоционального компонента толерантного отношения у обучающихся разных возрастных групп.СПИСОК ЛИТЕРАТУРЫ:
Социализация современных подростков: информационный контекст. //Вопросы психологии. Н А Голубева, Т Марцинковская, Голубева Н.А., Марцинковская Т.Д. Социализация современ- ных подростков: информационный контекст. //Вопросы психологии.- 2016. -№5.-С.15-28.
Психологические проблемы воспитания детей и школьников в условиях информационного общества.//Национальный психологический журнал. И В Дубровина, Дубровина И.В. Психологические проблемы воспитания детей и школьников в условиях информационного общества.//Национальный психологический журнал.-2018.-№1(29).-6-16
Толерантность как проблема воспитания. Н М Иванова, Иванова Н.М. Толерантность как проблема воспитания./Н.М.
Иванова// Гендерные основания механизмов и профилактика девиантного поведения личности в малых группах в XXI веке: материалы международного симпозиума 27-28 октября, Кострома.-Кострома. Иванова// Гендерные основания механизмов и профилактика деви- антного поведения личности в малых группах в XXI веке: материалы международного симпозиума 27-28 октября, Кострома.-Кострома, 2014.-С.119-122.
. В А Лабунская, Психология, Общения, Лабунская, В.А. и др. Психология затрудненного общения:
Коррекция: Учеб. пособие для студ. высш. учеб. Теория, Методы, Диагностика, Издательский центр «Академия. заведений/ В.А. Лабунская, Ю.А.Менджерицкая, Е.Д. Бреус-М.Теория. Методы. Диагностика. Коррекция: Учеб. пособие для студ. высш. учеб. заведений/ В.А. Лабунская, Ю.А.Менджерицкая, Е.Д. Бреус-М.: Издательский центр «Академия», 2001. -288с.
К операционализации понятия «толерантность» // Вопросы психологии. Д А Леонтьев, Леонтьев, Д.А. К операционализации понятия «толерант- ность» // Вопросы психологии. 2009. -№5. С3-16.
Диагностика и коррекция характерологических свойств личности: Учебное пособие. В М Минияров, Самара: АО «Корпорация Федоров. Минияров, В.М. Диагностика и коррекция характерологиче- ских свойств личности: Учебное пособие. -Самара: АО «Корпорация Федоров». 1997.-120с.
Социально-психологические факторы формирования отклоняющегося поведения несовершеннолетних// Психология. Историко-критические обзоры и современные исследования 2018, №1А. -С.14.21 8. Практическая психодиагностика. Методики и тесты./редактор-составитель Д. Д И Пономарева, Е А Пономарева, Я Райгородский -М.: Бахрах-М. 672Пономарева Д.И., Пономарева Е.А. Социально-психологические факторы формирования отклоняющегося поведения несовершенно- летних// Психология. Историко-критические обзоры и современные исследования 2018, №1А. -С.14.21 8. Практическая психодиагностика. Методики и тесты./редак- тор-составитель Д.Я Райгородский -М.: Бахрах-М, 2011, -672с.
Проблема интолерантности в современном обществе.// Социодинамика.-2016.-№6.-С.13-17 10. Толерантное сознание и формирование толерантных отношений (теория и практика): Сб.научн.-метод.ст. -2-е изд. М В Ростовцева, Ростовцева М.В. Проблема интолерантности в современном обществе.// Социодинамика.-2016.-№6.-С.13-17 10. Толерантное сознание и формирование толерантных отноше- ний (теория и практика): Сб.научн.-метод.ст. -2-е изд., стереотип. -М.: Издательство Московского психолого-социального института;
. Нпо Воронеж: Издательство, Модэк», Воронеж: Издательство НПО «МОДЭК», 2003. -368с.
Толерантность в культуре образования. //Профессиональное образование в современном мире. Н П Чупахин, В Д Павлова, 6Чупахин Н.П., Павлова В.Д. Толерантность в культуре обра- зования. //Профессиональное образование в современном мире. 2016 №6(2). С.228-235.
Диагностика и тренинг эмпатийных тенденций личности: Методическое руководство. -Казань: Татарское кн. издво. И М Юсупов, Юсупов, И.М. Диагностика и тренинг эмпатийных тенденций личности: Методическое руководство. -Казань: Татарское кн. изд- во, 1992. -32с.
| [
-0.0015036778058856726,
-0.18415507674217224,
-0.19298020005226135,
0.038576867431402206,
-0.34138694405555725,
0.035544537007808685,
-0.13557380437850952,
0.19952692091464996,
-0.15257787704467773,
0.2297305464744568,
-0.012019557878375053,
0.26190459728240967,
0.15583956241607666,
-0.027... |
Aging and Cancer Management Part I: Clinical Observations
M.DBruce A B J Peterson
M.D.Kennedy
Section of Medical Oncology
Depart ment of Medicine
Medicine and Director
Section of Medical Oncology
Department of Medicine
University of Minnesota Health Sciences Center
MinneapolisMinnesota
University of Minnesota Health Sciences Center
Minne apolis, Minnesota
Aging and Cancer Management Part I: Clinical Observations
a major health problem among elderly Americans. Dr. Peterson is Assistant Professor of Medi cine, CA-A CANCER JOURNAL FOR CLINICIANS 322
Although cancer is a common cause of disability and death in the elderly, rela tively little attention has been focused on the special problems presented by cancer in old age. The incidence of cancer rises sharply as the population ages; approxi mately 50 percent of all cancers occur in those who are over 65 years of age.1 The risk of developing cancer between the ages of 65 and 85 is 17 percent in women and 23 percent in men.2 This is con trasted with a probability of developing cancer between 20 and 40 years of age of one percent in men and 1.5 percent in women. In addition to the frequency of cancer seen in the later years, the number and proportion of elderly people in our population are steadily increasing. To day, over 22 million people in the United States are 65 years of age and over, and this number will more than double in the next 50 years, continuing to make cancer
The occurrence of cancer in the el derly presents the clinician with special problems in diagnosis and management. Certain cancers characteristically present in old age, and so the probability that a symptom complex is caused by a particu lar cancer varies with the age of the pa tient. Also, the behavior of cancer in the aged may be more or less aggressive than is the clinical course of the same tumor in younger patients. Aging and inter current illness may lessen the elderly in dividual's ability to withstand the effects of the tumor or the rigors of therapeutic intervention. There are also social and economic problems unique to the elderly individual with a serious, chronic disease. These factors must be considered in the management of the elderly patient.
For most cancers the incidence rises with age and then there appears to be a decline following 85 to 90 years of age.3 Certain cancers predominate in old age. A few primary sitesâ€"stomach, colon and rectum, prostate in men and breast in womenâ€"comprise over 50 percent of the invasive carcinomas in patients over 60 years of age.4 Lung cancer is common in elderly men and is becoming increasingly common in women. Cancer of the uter ine cervix is more common than was generally thought in women over 65 years of age,5 and the peak incidence of carcinoma of the endometrium follows that of the uterine cervix by several years. Another gynecologic cancer, epi dermoid carcinoma of the vulva, is espe cially a disease of the elderly. 6 When evaluating older patients, physicians should direct their attention to areas where cancer commonly occurs; patients should be encouraged to report all symp toms and not to assume that they are experiencing the natural effects of aging.
Although most tumors display little evidence of age-related variability in ag gressiveness, someâ€"such as melanoma, thyroid and breast carcinomaâ€"have been reported to display differing degrees of aggressiveness when the age of the pa tient is considered. For example, the five year survival rate for malignant mela noma remains relatively steady with in creasing age in women until they reach 60 years of age, after which time the five year survival rate sharply declines. 7 In men there appears to be a gradual decline in the survival rate following age 40.
Unfortunately, problems of cancer management in the elderly have not been studied to the extent that they have in younger patients. Many clinical studies focus on younger patients, while the aged patient is excluded from eligibility by arbitrary age limitations. Obviously, age should not be used either as an iso lated determinant or as an excuse not to treat vigorously. We shall review some of the data on host and tumor characteris tics that are age-related and can be ap plied to cancer management.
Thyroid Cancer
The risk of recurrence and death in creases with age in differentiated thyroid carcinoma.8'9 In a study of 600 patients with this cancer, followed for 15 to 45 years, low and high risk groups, based on age, could be determined.8 Death oc curred in 27 percent of the high risk group, which comprised males over 40 and females over 50 years of age. Among younger patients, only four percent died. The risk associated with age was more important than were pathologic type of thyroid tumor, local extension, site of recurrence, metastases, and type of treat ment. Recurrence and death in both men and women increased significantly with age and were maximal in those over 61 years old. This suggests that additional treatment, such as 1311and thyroid hor mone, should be considered following an adequate surgical resection of differenti ated thyroid carcinoma in the elderly. 10 Anaplastic carcinoma of the thyroid occurs predominantly in older patients. This is a virulent tumor with a median survival measured in months. There is evidence that most anaplastic carcinomas of the thyroid are preceded by a differ entiated carcinoma.11@12For this reason, any sudden change in a thyroid nodule of an older person should immediately be investigated. Early reports of intensive multimodality therapy using chemother apy, thyroid hormone, 131!and immuno therapy have been encouraging.13
Breast Cancer
Breast cancer in women is of great im portance because of the large number of new cases each year. The incidence in creases with age, and one-half of all cases occur in patients over 65 years of age.'4 Although there are not substantial age related differences in the stage of disease at the time of diagnosis, the general im pression is that older women tend to have a more benign and protracted clinical course, with metastatic disease. In un treated breast cancer, however, average survival remains at approximately 40 months for women between 45 and 75 years of age at the time of diagnosis.'4 The mean survival is shorter in women diagnosed at either below 35 or over 75 years old and, within these groups, does not improve with age.
Surgery
The primary surgical treatment of breast cancer in the elderly is as successful as in younger patients. Similar adjusted five year rates were found for patients either above or below 65 years of age who were treated with mastectomy.'5 However, the younger patients (p < 0.01) to both phenylalanine mustard and the standard combination of cyclophosphamide, meth otrexate and 5-fluorouracil. 22 these possibilities contributes to the lack of demonstrated effectiveness of adju vant chemotherapy in postmenopausal women is unclear. In any case, at this time it is difficult to justify a routine use of adjuvant chemotherapy in postmeno pausal women with breast cancer. As mentioned, the response of meta static breast carcinoma to certain drugs may vary with age. 5-Fluorouracil in duces its highest response rates in young patients, but Adriamycin seems to be especially effective in older patients.21 '23 In other studies this has also been ob served with Adriamycin in combination chemotherapy.@'25 It has been consis tently observed that decreased response rates occur in elderly patients treated with combinations that do not include Adriamycin.2l@22.U@26 One may conclude that initial chemotherapy for postmeno pausal women with metastatic breast cancer should probably include Adna mycin.
Hormonal Treatment
Older women hold an advantage over younger women regarding hormonal management of metastatic disease. Tu mor regression with estrogen therapy steadily increases with age in postmeno pausal women. In one report, regression of metastatic breast cancer occurred in 18 percent of women under 60 years of
Adjuvant Chemotherapy
For those patients found to have axillary lymph node involvement, the use of ad juvant chemotherapy must be considered. Unfortunately, the results of major stud ies do not indicate a significant advantage in survival for postmenopausal women who receive adjuvant chemotherapy.'@20 This is not the case in premenopausal women, where adjuvant therapy is bene ficial. Why the disparity exists is not un derstood, but there are several possible explanations: (1) The possibility of bene fit to premenopausal women, through a chemotherapy-induced oophorectomy has been considered and is being actively evaluated. (2) The dosage of medication may also be important. In the report of adjuvant chemotherapy by Bonadonna et al,'8 women over 65 years of age were started on lower doses of both metho trexate and 5-fluorouracil. These doses may have been inadequate, perhaps lim iting the effectiveness of adjuvant ther apy. (3) Another possibility is that re sponse to individual chemotherapeutic agents is itself related to age.
Although the response of breast can cer to cyclophosphamide does not vary appreciably with age, there does appear to be a progressive decrease in response to 5-fiuorouracil. 21 Canellos et al have also reported that older patients with metastatic disease respond less than do age, in 32 percent of women 60 to 69 years, in 39 percent of women 70 to 79 years and in 59 percent of women 80 years of age and over (p <0.01) @27 The increased estrogen receptor binding ca pacity found in the breast cancers of older women helps to explain this obser vation. If the tumor cells are rich in estrogen receptors, a response to hor monal therapy is predicted in about one half of both pre-and postmenopausal women; when malignant cells are estro gen receptor-poor, response to hormonal manipulation is rare. In the premeno pausal group, the incidence of estrogen receptor-rich tumors is only about 40 percent. This incidence rises with age in postmenopausal women and reaches 75 to 80 percent in patients over 75 years of age.28
If elderly women with metastatic breast cancer exhibit a good response to initial estrogen therapy, other hormonal manipulations are likely to produce fur ther benefit following relapse in a high proportion of patients. These women may improve considerably after either hypophysectomy29'3°or adrenalectomy3' and, subsequently, the use of the new antiestrogen compounds.32 Significantly higher response rfltes (56 percent) to Tamoxifen were reported in women who were more than 10 years postmenopause than in those who were less than 10 years beyond menopause (41 percent) @32 Hor monal therapy has proven to be of great benefit for many elderly women with metastatic breast cancer and, if utilized appropriately, frequently controls the disease over an extended period of time before cytotoxic chemotherapy is war ranted.
Prostate Cancer
Cancer of the prostate is very common in elderly men and may be detected dur ing a physical examination or autopsy in 40 to 57 percent of those over 70 or 80 years of age.33'34 Although some studies find that elderly men with prostate carci noma live longer than younger men,35@@ others find that the elderly have equal or shorter survival when compared to younger patients.37-39 Further, survival in prostate cancer correlates well with the extent of disease at diagnosis, which, in turn, seems to bear no relationship to age at diagnosis;39 similar proportions of early and late stage disease occurred in all age groups. Also, no difference was found in the distribution of histologic grades when the age at diagnosis was considered. This lack of age-determined differences in pathologic features that carry prognostic significance has been noted by others.
Local Treatment
Prostatic carcinoma is almost always ad vanced at the time of diagnosis. When local therapy, e.g., surgery and irradia tion, is indicated, the clinical status of the patient must be gauged with regard to the extent of disease or intercurrent illness as well as the risks and potential benefits of therapeutic intervention. The results of surgery in the treatment of prostate cancer are not related to age. Similarly, the use of external beam ir radiation may be beneficial when used for specific stages, regardless of age.
HormoneTherapy
The management (systemic treatment) of advanced prostate cancer must also be tempered by the clinical status of the patient. The benefits of estrogen therapy and the accompanying risk of cardio vascular complications are both well doc umented in the Veterans Administration studies.40 '41 It has been demonstrated that younger patients with prostate can cer die of the cancer but that older pa tients most often die from other causes. 39 This was certainly true among those patients over 55 years of age treated with estrogen; the mortality from cardiovas cular disease increased with age regard less of the presence or absence of identifi able underlying cardiovascular disease. However, the risk was nearly doubled in patients who had preexisting cardiovas cular disease, compared to patients of equivalent age without known cardio vascular disease. Thus, estrogen therapy should be employed cautiously in old patients.
younger patients with prostate cancer die of the cancer, but older patients most often die from other causes.― Since orchiectomy is equally effective in palliating advanced prostate cancer, strong consideration should be given to using it in place of estrogen therapy in the elderly patient. When hormonal ma nipulation fails, several chemotherapeu tic agents, known to be efficacious in the treatment of metastatic prostate cancer, can be given. However, there are no data on possible age-related differences in response.
Leukemia
ChronicLymphocytic Leukemia
Chronic lymphocytic leukemia is a monoclonal accumulation of malignant B lymphocytes that characteristically oc curs in older individuals. The clinical course is considered relatively indolent because the median survival is often re ported to be six or more years; nearly one-third of patients live long enough to die of causes unrelated to the leukemia. 42 Unfortunately, not all patients with chronic lymphocytic leukemia do as well as would be expected from the classic image of this disease. The elderly are one group whose prognosis is less favorable. Patients over 60 and 70 years of age have median survivals of approximately 58 and 30 months, respectively,42-44 and these are considerably shorter than those observed in younger patients.
One of the reasons for the shorter survival in older individuals is that they usually have more advanced disease at diagnosis,42.43but it is not known whether chronic lymphocytic leukemia is actually more aggressive in the elderly. The rel atively poor median survival of patients over 70 years of age (30 months) is al most entirely due to their advanced stage at diagnosis. A clinical staging system has been proposed for patients with chronic lym phocytic leukemia, based on the assump tion that there is prognostic significance in the accumulation of malignant lym phocytes over time. 43 Patients presenting with only lymphocytosis have the best outlook, with a median survival of more than 150 months. Splenomegaly and/or hepatomegaly generally indicate an un favorable prognosis. Anemia and throm bocytopenia denote the worst prognosis, with a median life expectancy of just 19 months.
Not all patients with chronic lym phocytic leukemia require treatment. When therapy is employed it should be initiated only for specific indications, such as uncomfortable organomegaly, anemia or thrombocytopenia. Treatment is usually started with either prednisone or a single alkylating agent, which will result in significant alleviation of symp toms for most patients. Since individuals with chronic lymphocytic leukemia are immunosuppressed by the leukemia, drugs that might further impair immu nity must be used with caution. Despite the contribution of chemotherapy to the well-being of some patients, there is no evidence that it generally prolongs sur vival. It is clear that new approaches to the management of chronic lymphocytic leukemia are needed, particularly in pa tients with a poor prognosis.
Acute Nonlymphocytic Leukemia
Considerable pessimism has developed concerning the treatment of elderly pa tients with acute nonlymphocytic leu kemia. This is of particular concern, since approximately 40 percent of all cases occur in patients over 60 years of age.45 It has been implied that leukemia in the elderly may be more resistant to therapy and that the aged cannot toler ate the intensive therapy necessary to induce complete remission. As a result of this pessimism, conservative therapy â€oe¿ ... advances in induction therapy...
have resulted in an improved prognosis for the elderly patient with leukemia.― is often advocated for the elderly pa tient, despite the fact that this approach usually results in neither complete re missions nor improved survival.@ Al though some elderly patients may have slowly progressive or smoldering leu kemia, acute nonlymphocytic leukemia in elderly patients is generally as ag gressive as in young patients. For all patients with this disease, it is apparent that the single most important factor in prolonging survival is the achievement of complete remission.47-5°I n 1974, it was reported that com plete remission could be obtained in pa tients with acute nonlymphocytic leu kemia who were over 60 years of age.5' A prospective trial confirmed that elderly patients could be treated successfully with the same intensive, multidrug regimens that are used in the treatment of younger adults. 48 The duration of complete re mission was comparable to that attained in younger adults, and the median sur vival for the elderly who achieved a com plete remission was 23 months. The re sponders spent the better part of their remaining life out of the hospital.
In the past few years there have been reports of high complete remission rates in adults with acute nonlymphocytic leu kemia.47'49'50 A five-drug induction chemotherapy program resulted in com plete remission in 82 percent of un selected patients of all ages presenting with acute nonlymphocytic leukemia; in patients over 60 years of age, 71 percent had complete remission. 49 Comparable response rates in the elderly have been observed in other series.47 '50 In addition to prolonging survival, the achievement of complete remission re suits in an improved quality of life. Pa tients in remission may continue to pur sue their work or retirement activities. Although underlying health at diagnosis remains an important prognostic con sideration for patients with acute non lymphocytic leukemia, advances in in duction therapy and supportive care have resulted in a changing attitude and an improved prognosis for the elderly pa tient with leukemia.
Lung Cancer
The incidence of lung cancer is con tinuing to increase in the general popu lation. Since most pulmonary cancers are related etiologically to the carcino gens in tobacco smoke, it is likely that the duration of regular exposureâ€"rather than ageâ€"correlates best with the inci dence in a given population.52'53 Since lung cancer occurs with increasing fre quency over a period of time in a popu lation that places itself at risk, many lung cancers arise in the elderly.
Surgery
Despite the relatively small percentage of cases in which total surgical resection of the tumor is possible, surgery remains the primary therapeutic modality that may result in cure. The procedures re quired for curative resection carry con siderable risk and there is a general re luctance to subject aged patients to them. However, the clinical course of unre sected lung cancer in the elderly is as dismal as it is in younger patients, with 22 percent alive at six months and only seven percent surviving 12 months.M The operative mortality for pneumo nectomy and lobectomy in patients over 65 years of age has been reported at six to 28 percent54-56â€"approximately twice that observed in younger patients with lung cancer.54 Careful preoperative evaluation, with an assessment of cardio pulmonary function and a search for metastatic disease, will help select pa tients who are suitable candidates for a thoracotomy. Bronchoscopy and medi astinoscopy may obviate the need for thoracotomy in some patients. For the 15 to 30 percent of patients who have resectable tumors, survival at four or five years ranges from 12 to 40 percent.54-56 Although this represents a very small proportion of all elderly patients with lung cancer, these few survive consider ably longer than do patients with tumors that cannot be resected.
Radiotherapy and Chemotherapy
For those patients with unresectable lung cancer, other forms of therapy should be considered. In selected patients, radio therapy may result in cure.57'58 These patients must have adequate respiratory reserve because high-dose irradiation to the lung frequently causes a loss of func tional capacity.
Considerable progress has also been made in the chemotherapeutic manage ment of lung cancer. For the first time, drug regimens are proving regularly ef fective in non-small cell carcinoma,59@60 and small cell carcinoma of the lung is now one of the cancers most responsive to chemotherapyâ€"the median survival having improved from two months to ap proximately 12 months with intensive combination chemotherapy.61'62 Despite the optimism generated by these results, the vast majority of both old and young individuals with lung cancer will con tinue to die of it.
Gastrointestinal Cancer
Gastrointestinal cancers comprise be tween 25 and 44 percent of all cancers occurring after 75 years of age;4 exact percentages depend on the patients' sex and age. The symptoms of gastrointesti nal cancer may be minimal, and promi nent among them are weight loss, alterations in bowel habits, new abdomi nal hernias and unexplained anemia. It is incumbent upon physicians to seriously consider any such complaints in the elderly patient. Symptoms of gastroin testinal disturbance should be actively sought when the medical history is ob tained, and the elderly patients should be encouraged not to minimize these symp toms if they occur.
The diagnostic approach to gastro intestinal cancer must take the elderly patient's underlying health into con sideration. Barium enemas and other procedures should be prescribed cau tiously, and catharsis should be gentle.
Surgery
The initial therapeutic approach to pa tients with gastric or colorectal carci noma is surgical, and this is true also for the aged patient. Abdominal surgery is a serious undertaking in an elderly indi vidual with cancer, but the nature of the disease requires it for cure or, frequently, for palliation. A surgeon contemplating a major operation in an elderly patient must weigh the risks against the poten tial benefits. Careful preoperative prepa ration and correction of intercurrent medical problems wifi help to limit the risks of major surgery. However, the operative mortality may range from five to 12 percent.63 '64 Most patients with gastrointestinal cancer are not cured by surgery because the disease has metastasized. In a large group of untreated patients with incur able gastric or colon carcinoma, age did not affect the median survival in patients under 80 years of age.65 However, me dian survival time was reduced by ap proximately two-thirds in patients over 80 years. Interestingly, a steady increase in the proportion of long-term survivors occurred over time, suggesting that a small subset of elderly patients with gas trointestinal cancer had more slowly growing tumors.
in whom the surgical procedure seemed incidental to their death, and with newer advances in surgical techniques and the physiologic monitoring of patients, oper ative mortality in cancer patients will be reduced. As long as surgical pro â€oe¿ As long as surgical procedures are well planned and patients are carefully selected, major cancer surgery in the elderly is justffied.― cedures are well planned and patients are carefully selected, major cancer sur gery in the elderly is justified.
Little is known of the toxic effects of chemotherapeutic drugs as they occur specifically in the aged. The ability of hematopoietic cells to recover following myelosuppressive chemotherapy seems to be retained despite aging, but there is less functional bone marrow in an elderly patient. This may occasionally result in unexpectedly profound neutropenia or thrombocytopenia. The use of agents with other potentially adverse effects, such as the impairment of cardiac or pulmonary function, should be moni tored closely because some elderly indi viduals will not tolerate even a minimal reduction in function. Most patients will, however, tolerate full doses when chemo therapy is used with appropriate caution.
General considerations of health problems other than the cancer fre quently influence the management of the aged patient, for these problems may complicate or compromise therapy of the cancer. Also, a nonmalignant disease is sometimes of overriding importance to the health of the individual, and active therapy of the cancer may be compara tively trivial. The appearance of new symptoms in a patient with a past history or present diagnosis of cancer requires full evaluation. The symptoms may sig nal the occurrence of a different disease, Chemotherapy 5-Fluorouracil has been the major chemotherapeutic drug employed against advanced gastrointestinal carcinoma. Al though it is effective in only a minority of patients, it has not been supplanted by other agents. In a large study, the per centage of objective regressions with 5-fluorouracil fell with increasing age.@ In patients 45 to 69 years of age, 19 per cent attained objective regression, but in patients 70 years of age and over, only eight percent achieved regression. These differences were not statistically signifi cant. Similar age-related decreases in drug response rates have been observed with both sequential and combination chemotherapy of gastric carcinoma.67 Despite these observations, the needs of the patient and his underlying health should be the major determinants in se lecting palliative chemotherapy.
Summary and Conclusions
It is apparent that the consequences of aging must be considered in the manage ment of elderly patients with cancer. Al though strategy will not be modified in most instances because of age, physicians must be able to recognize when the more conservative diagnostic or therapeutic approaches are warranted. Some patients will not benefit from extensive evalua tion, surgery or chemotherapy, yet in these individuals, the resources of the health care team still have much to offer. The great majority of elderly patients, however, will profit from comprehensive management, including specific efforts to treat the cancer.
Surgery can be successfully em ployed in the treatment of cancer, but the surgeon must recognize that there are increased risks associated with its use in the aged.54-56'63'64'68At the Memorial Sloan-Kettering Cancer Center, the op erative mortality from all causes was 50 percent higher among patients over 70 years of age than in those under 70 years old.64 But these results included patients including a new primary cancer, and should not automatically be ascribed to the previous cancer.
Adequate attention must be focused on managing anxiety, pain and nausea, because the successful control of these often constitutes a major achievement in the management of advanced cancer. Al though drugs may be extremely bene ficial in controlling these symptoms, the possibility of adverse drug interactions should be anticipated and potentially hazardous reactions prevented. Support by the health care team in meeting the References patient's emotional and social needs also contributes immeasurably to the allevia tion of these problems.
Physicians who care for elderly pa tients with cancer must exercise in formed judgment in planning individual management programs. Careful con sideration must be given to the occur rence and behavior of specific cancers in the elderly, and patients' ability to toler ate the rigors of therapeutic intervention. Although the patient's age is an impor tant determinant, decisions cannot be made on that basis alone.
advanced breast cancer. Cancer35:1108-1115, 1975. 25. Tranum B, et al: Adniamycin in com bination for the treatment of breast can cer: a Southwest Oncology Group Study. Cancer 41:2078-2083, 1978. 26. Ahmann DL, et al: An analysis of a multiple-drug program in the treatment of patients with advanced breast cancer utiliz ing 5-fluorouracil, cyclophosphamide, and prednisone with or without vincristine. Can cer 36:1925-1935, 1975. 27. Stoll BA: Hypothesis: breast cancer re gression under oestrogen therapy. Br Med 1 3:446-450, 1973. 28. McGuire WL, Pearson OH, Segaloff A: Predicting hormone responsiveness in hu man breast cancer, in McGuire WL, Car
Multimodality treatment for high risk thyroid carcinoma. B Dune, Proc Am Assoc for Cancer Res and ASCO. 171976abstractDune B, et a!: Multimodality treatment for high risk thyroid carcinoma. Proc Am Assoc for Cancer Res and ASCO 17:277, 1976 (abstract).
C D Haagensen, Diseases of the Breast. Philadelphia, WB SaundersRevised second editionHaagensen CD: Diseases of the Breast. Revised second edition, Philadelphia, WB Saunders, 1971, pp 380-465.
Breast cancer in elderly women. D Schottenfeld, O F Robbins, Geriatrics. 26Schottenfeld D, Robbins OF: Breast cancer in elderly women. Geriatrics 26:121- 131, 1971.
Modified mas tectomy for older, poor risk patients. J W Berg, O F Robbins, Surg GynecObstet. 113Berg JW, Robbins OF: Modified mas tectomy for older, poor risk patients. Surg GynecObstet 113:631-634, 1961.
Radical mas tectomy in the aged female. A F Cortese, O N Cornell, J Am Oeriatr Soc. 23Cortese AF, Cornell ON: Radical mas tectomy in the aged female. J Am Oeriatr Soc 23:337-342, 1975.
Combination chemotherapy as an adjunct treatment in operable breast cancer. Bonadonna 0, N Eng! J Med. 294Bonadonna 0, et al: Combination chemotherapy as an adjunct treatment in operable breast cancer. N Eng! J Med 294: 405-410, 1976.
Are surgical ad juvant trials altering the course of breast cancer?. Bonadonna 0, Sem Oncol. 5Bonadonna 0, et al: Are surgical ad juvant trials altering the course of breast cancer? Sem Oncol 5:450-464, 1978.
. B Fisher, l-Phenylalanine musFisher B, et a!: l-Phenylalanine mus
. ! Eng, J Med. 292Eng! J Med 292:117-122, 1975.
Combination chemotherapy of carcinoma of the breast. L E Broder, D C Tormey, Broder LE, Tormey DC: Combination chemotherapy of carcinoma of the breast.
. CancerTreat Rev. 1CancerTreat Rev 1:183-203, 1974.
Combination chemotherapy for metastatic breast carci noma. Prospective comparison of multiple drug therapy with L-phenylalanine mustard. O P Canellos, Cancer. 38Canellos OP, et al: Combination chemotherapy for metastatic breast carci noma. Prospective comparison of multiple drug therapy with L-phenylalanine mustard. Cancer 38:1882-1886, 1976.
Adriamycin (NSC 123127) in the treatment of advanced breast cancer: studies by the Southwest Oncology Group. B Hoogstraten, Cancer Chemother Rep. 6Hoogstraten B: Adriamycin (NSC 123127) in the treatment of advanced breast cancer: studies by the Southwest Oncology Group. Cancer Chemother Rep 6:329-334, 1975.
Third Na tional Cancer Survey: Incidence Data. Nati Cancer Inst Monogr. Cutler SJ, Young JL41NIHDREW Publi cation NoUS Government Printing OfficeCutler SJ, Young JL (eds): Third Na tional Cancer Survey: Incidence Data, Nati Cancer Inst Monogr No 41, DREW Publi cation No (NIH) 75-787. Washington, US Government Printing Office, 1975.
Probabilities of eventually developing and of dying of cancer (risk among persons previously undiagnosed with the cancer). H Seidman, E Silverberg, A Bodden, Ca. 28Seidman H, Silverberg E, Bodden A: Probabilities of eventually developing and of dying of cancer (risk among persons previously undiagnosed with the cancer). Ca 28:33-46, 1978.
Cancer in old age. E A Lew, Ca. 28Lew EA: Cancer in old age. Ca 28:2-6, 1978.
Siegler EE: Cervical carcinoma in the aged. S J Cutler, H Eisenberg, Am J Obstet Gynec. 114Ann NY Acad SciCutler SJ, Eisenberg H: Cancer in the aged. Ann NY Acad Sci 114:771-781, 1964. S. Siegler EE: Cervical carcinoma in the aged. Am J Obstet Gynec 103:1093-1097, 1969.
Gynecologic onology in the aged. J L Breen, Clin Obstet Gynec. 10Breen JL: Gynecologic onology in the aged. Clin Obstet Gynec 10:498-518, 1967.
Endocrine influences on survival from malignant melanoma. H M Shaw, G W Milton, G Farago, W H Mccarthy, Can cer. 42Shaw HM, Milton GW, Farago G, McCarthy WH: Endocrine influences on survival from malignant melanoma. Can cer 42:669-677, 1978.
Risk factor analysis in differentiated thyroid cancer. B Cady, Cancer. 43Cady B, et al: Risk factor analysis in differentiated thyroid cancer. Cancer 43: 810-820, 1979.
Prognosis in thyroid car cinoma. K O Franssila, Cancer. 36Franssila KO: Prognosis in thyroid car cinoma. Cancer 36:1138-1146, 1975.
Papillary thyroid carcinoma: the impact of therapy in 576 patients. E L Mazzaferri, Medicine. 56Mazzaferri EL, et al: Papillary thyroid carcinoma: the impact of therapy in 576 patients. Medicine 56:171-196, 1977.
Thyroid carcinoma biologic behavior and mortality. Postmor tem findings in 42 cases, including 27 in which the disease was fatal. M L Ibanez, Cancer. 19Ibanez ML, et a!: Thyroid carcinoma biologic behavior and mortality. Postmor tem findings in 42 cases, including 27 in which the disease was fatal. Cancer 19: 1039-1052, 1966.
Anaplastic spindle-cell and giant-cell tumors of the thyroid gland. Nishiyama, Rh, E L Dunn, N W Thompson, Estrogen Re ceptors in Human Breast Cancer. bone PP. Vollmer EPNew YorkRaven Press30Nishiyama. RH, Dunn EL, Thompson NW: Anaplastic spindle-cell and giant-cell tumors of the thyroid gland. Cancer 30: 113-127, 1972. bone PP. Vollmer EP (eds): Estrogen Re ceptors in Human Breast Cancer. New York, Raven Press, 1975, pp 17-30.
Hypophysec tomy in advanced breast cancer. B J Kennedy, L French, Am I Surg. 110Kennedy BJ, French L: Hypophysec tomy in advanced breast cancer. Am I Surg 110:411-415, 1965.
Hypo physectomy in metastatic breast cancer. J C Vangilder, I S Goldenberg, Arch Surg. 110VanGilder JC, Goldenberg IS: Hypo physectomy in metastatic breast cancer. Arch Surg 110:293-295, 1975.
The results of adrenalectomy in ad vanced breast cancer in 500 consecutive pa tients. Randall Fracchiaaa, Ht, J H Farrow, Surg Gynec Obstet. 125FracchiaAA, Randall HT, Farrow JH: The results of adrenalectomy in ad vanced breast cancer in 500 consecutive pa tients. Surg Gynec Obstet 125:747-756, 1967.
Antihormone treatment of StageIV breast cancer. A Manni, 43Manni A, et al: Antihormone treatment of StageIV breast cancer. Cancer43:444- 450,1979.
Carcinoma of the prostate in elderly men: incidence, growth characteristics and clinical significance. Scott R Jr, D L Mutchnik, T Z Laskowski, W R Schmalhorst, I Urol. 101Scott R Jr, Mutchnik DL, Laskowski TZ, Schmalhorst WR: Carcinoma of the prostate in elderly men: incidence, growth characteristics and clinical significance. I Urol 101:602-607, 1969.
Pathology of neoplasms of theprostate gland. I Waisman, Lim Mott, Genitourinary Cancer. Philadelphia, WB Saunders. inSkinner DG, deKernionJBWaisman I, Mott LIM: Pathology of neoplasms of theprostate gland, inSkinner DG, deKernionJB (eds):Genitourinary Cancer. Philadelphia, WB Saunders, 1978, pp 310-343.
Carcinoma of the prostate: a 15-year followup. K A Hanash, J Urol. 107Hanash KA, et al:Carcinoma of the prostate: a 15-year followup. J Urol 107: 450-453, 1972.
Prostatic adenocarcinoma occurring inmen under50 years of age. D E Johnson, J P LanieriJr, A G Ayala, J. 4Johnson DE, Lanieri JP Jr, Ayala AG: Prostatic adenocarcinoma occurring inmen under50 years of age.J SungOncol4:207- 216, 1972.
Cancer of the prostate in men less than 50 years old: an analysis of 51 cases. D P Byar, F K Mostofi, J Urol. 102Byar DP, Mostofi FK: Cancer of the prostate in men less than 50 years old: an analysis of 51 cases. J Urol 102:726-733, 1969.
Adenocarci noma of the prostate in men less than 56 years old: a study of 65 cases. I Silber, M H Mcgavran, J Urol. 105Silber I,McGavran MH: Adenocarci noma of the prostate in men less than 56 years old: a study of 65 cases. J Urol 105: 283-285, 1971.
Byar DP: Proceedings: The Veterans Administration Cooperative Urological Re search Group's studies of cancer of the prostate. I N CorriereJr, I L Cornog, J J Murphy, Cancer. 25CancerCorriere IN Jr, Cornog IL, Murphy JJ: Prognosis in patients with carcinoma of the prostate. Cancer 25:911-918, 1970. 40. Byar DP: Proceedings: The Veterans Administration Cooperative Urological Re search Group's studies of cancer of the prostate. Cancer 32:1126-1130, 1973.
Incidence of cardiovascular dis ease and death in patients receiving di ethyistilbestrol for carcinoma of the pros tate. C E Blackard, R P Doe, G T Mellinger, D P Byar, Cancer. 26Blackard CE, Doe RP, Mellinger GT, Byar DP: Incidence of cardiovascular dis ease and death in patients receiving di ethyistilbestrol for carcinoma of the pros tate. Cancer 26:249-256, 1970.
Factors influencing the duration of survival of patients with chronic lymphocytic leukemia. D R Bo@, S A Sofferman, M M Wintrobe, G E Cartwright, Am I Med. 40Bo@ DR, Sofferman SA, Wintrobe MM, Cartwright GE: Factors influencing the duration of survival of patients with chronic lymphocytic leukemia. Am I Med 40:243-254, 1966.
Clinical staging of chronic lymphocytic leukemia. K R Rai, Blood. 46Rai KR, et al: Clinical staging of chronic lymphocytic leukemia. Blood 46: 219-234, 1975.
Survival in chronic lymphocytic leuke mia. C Zippin, Cutler Si, Reeveswj Ir, D Lum, Blood. 42Zippin C, Cutler Si,ReevesWJ ir, Lum D: Survival in chronic lymphocytic leuke mia. Blood 42:367-376, 1973.
Acute leukemia over the age of fifty: a study of its incidence and natural history. F W Gunz, R F Hough, Blood. 11Gunz FW, Hough RF: Acute leukemia over the age of fifty: a study of its incidence and natural history. Blood 11:882-901, 1956.
Quality and quantity of survival in acute myeloid leukaemia. P S Burge, Lancet. 2Burge PS, et al: Quality and quantity of survival in acute myeloid leukaemia. Lancet 2:621-624, 1975.
Intensive chemoimmunotherapy in acutemyelogenous leukemia (AML). R P Gale, I Zighelboim, K A Foon, M I Cline, Blood. 52abstractGale RP, Zighelboim I, Foon KA, Cline MI: Intensive chemoimmunotherapy in acutemyelogenous leukemia (AML). Blood 52:250, 1978 (abstract).
Treat ment of acute nonlymphocytic leukemia in elderly patients: a prospective studyof in tensive chemotherapy. B A Peterson, C D Bloomfield, Cancer. 40Peterson BA, Bloomfield CD: Treat ment of acute nonlymphocytic leukemia in elderly patients: a prospective studyof in tensive chemotherapy. Cancer 40:647-652, 1977.
Rapid remission induction with intensive chemotherapy in adult acute non-lymphocyticleukemia (ANLL). B A Peterson, Blood. 52abstractPeterson BA, et al: Rapid remission induction with intensive chemotherapy in adult acute non-lymphocyticleukemia (ANLL). Blood 52:269, 1978 (abstract).
Treatment of acute myeloid leukemiawith a triple cytotoxic regime: DAT. Jkh Rees, Sandierrm, J Challener, F G Hayhoe, BrJ. 36Rees JKH, SandierRM, Challener J, Hayhoe FG: Treatment of acute myeloid leukemiawith a triple cytotoxic regime: DAT. BrJ Cancer36:770-776, 1977.
Acute granulocytic leukemia in elderly patients. C D Bloomfield, A Theologides, JAMA. 226Bloomfield CD, Theologides A: Acute granulocytic leukemia in elderly patients. JAMA 226:1190-1193, 1973.
The age distribution of cancer: implications for models of carcinogenesis. R Doll, Doll R: The age distribution of cancer: implications for models of carcinogenesis.
. JR Statist Soc. 134133JR Statist Soc 134:133, 1971.
Riskof lungcanceraccord ingtohistologic typeand cigarette dosage. W Weiss, K R Boucot, H Seidman, Carnahanwi , JAMA. 22Weiss W, Boucot KR, Seidman H, CarnahanWI: Riskof lungcanceraccord ingtohistologic typeand cigarette dosage. JAMA 22:799-801, 1972.
Resection for bronchial carcinomaintheelderly. E W Evans, Thorax. 28Evans EW: Resection for bronchial carcinomaintheelderly. Thorax 28:86-88, 1973.
Carcinoma of the lung in the elderly. Okinakaaj, C W Holman, Am Rev Respir. 93OkinakaAJ, Holman CW: Carcinoma of the lung in the elderly. Am Rev Respir Dis93:578-583, 1966.
Pulmonary resection for bronchogenic car cinoma in geriatric patients. D M Sensenig, N P Rossi, J L Ehrenhaft, Ann Thorac Surg. 2Sensenig DM, Rossi NP, Ehrenhaft JL: Pulmonary resection for bronchogenic car cinoma in geriatric patients. Ann Thorac Surg 2:508-5 13, 1966.
Radiotherapy of bronchogenic carcinoma. R E Lee, Scm Oncol. 1Lee RE: Radiotherapy of bronchogenic carcinoma. Scm Oncol 1:245-252, 1974.
Radiation therapy in small cell lung cancer. H G Seydel, R H Creech, W Mietlowski, C Perez, Sem Oncol. 5Seydel HG, Creech RH, Mietlowski W, Perez C: Radiation therapy in small cell lung cancer. Sem Oncol 5:288-298, 1978.
Metastatic non-oat cell bronchogenic carcinoma. Therapy with cyclophosphamide, doxorubicin, methotrex ate, and procarbazine (CAMP). J D Bitran, R K Desser, T Demeester, H M Golomb, JAMA. 240Bitran JD, Desser RK, DeMeester T, Golomb HM: Metastatic non-oat cell bronchogenic carcinoma. Therapy with cyclophosphamide, doxorubicin, methotrex ate, and procarbazine (CAMP). JAMA 240:2743-2746, 1978.
Chemotherapy for bronchogenic carcinoma: methotrexate, doxorubicin, cyclophosphamide, and lomus tine. A P Chahinian, JAMA. 237Chahinian AP, et a!: Chemotherapy for bronchogenic carcinoma: methotrexate, doxorubicin, cyclophosphamide, and lomus tine. JAMA 237:2392-2396, 1977.
Superiority of a four-drug combination to a three-drug combination. H H Hansen, P Dombernowsky, M Hansen, F Hirsch, Ann Intern Med. 89Chemotherapy of advanced small-cell anaplastic carcinomaHansen HH, Dombernowsky P. Hansen M, Hirsch F: Chemotherapy of advanced small-cell anaplastic carcinoma. Superiority of a four-drug combination to a three-drug combination. Ann Intern Med 89:117-181, 1978.
Small-cell carci noma of the lung: combined chemotherapy and radiation. A Southwest Oncology Group Study. R B Livingston, Ann Intern Med. 88Livingston RB, et al: Small-cell carci noma of the lung: combined chemotherapy and radiation. A Southwest Oncology Group Study. Ann Intern Med 88:194-199, 1978.
Analysis of geriatric surgical experience in a veterans home. R J Jake, J Am Geriatr Soc. 24Jake RJ: Analysis of geriatric surgical experience in a veterans home. J Am Geriatr Soc 24:374-378, 1976.
Surgical mortality among the elderly. An analysis of 4,050 operations (1970-1974). A D Turnbull, E Gundy, W S Howland, Beattie El, Clin Bull. 8Turnbull AD, Gundy E, Howland WS, Beattie El: Surgical mortality among the elderly. An analysis of 4,050 operations (1970-1974). Clin Bull 8:139-142, 1978.
Advanced Gastrointestinal Cancer: Clinical Management and Chemo therapy. C G Moertel, Moertel CO. Reite meier RINew York, HoeberNatural history of gastro intestinal cancerMoertel CG: Natural history of gastro intestinal cancer, in Moertel CO. Reite meier RI (eds): Advanced Gastrointestinal Cancer: Clinical Management and Chemo therapy. New York, Hoeber, 1969, pp 3-14.
Clinical features influencing therapeutic response to fluorinated pyrimidines. C G Moertel, R I Reitemeier, Advanced Gastroin testinal Cancer: Clinical Management and Chemotherapy. Moerte! CG, Reitemeier RNew York, HoeberMoertel CG, Reitemeier RI: Clinical features influencing therapeutic response to fluorinated pyrimidines, in Moerte! CG, Reitemeier R (eds): Advanced Gastroin testinal Cancer: Clinical Management and Chemotherapy. New York, Hoeber, 1969, pp 122-125.
Sequential and com bination chemotherapy of advanced gastric cancer. C O Moertel, Cancer. 38Moertel CO, et al: Sequential and com bination chemotherapy of advanced gastric cancer. Cancer 38:678-682, 1976.
Surgery for gynecologic malignancy in the aged. R L Pierson, P K Figge, Buchsbaum Hi, Obstet Gynecol. 46Pierson RL, Figge PK, Buchsbaum Hi: Surgery for gynecologic malignancy in the aged. Obstet Gynecol 46:523-527, 1975.
| [
0.14057186245918274,
0.07439842820167542,
-0.05538404360413551,
-0.01120782271027565,
-0.09448327124118805,
-0.004471698310226202,
0.0030742092058062553,
0.09308335930109024,
-0.007515765726566315,
0.05744600668549538,
0.012267228215932846,
0.02669679746031761,
0.1608637273311615,
-0.03770... |
El riñón del niño prematuro: riesgos a largo plazo The kidney of the premature child: long-term risks
2020
Felipe Cavagnaro Sm fcavagnaro@alemana.clcómocitaresteartículo:revchilpediatr.2020
clínica Alemana de Santiago. Facultad de Medicina, clínica Alemana
correspondencia: Felipe cavagnaro SM
El riñón del niño prematuro: riesgos a largo plazo The kidney of the premature child: long-term risks
ActuAlidAd Rev chil Pediatr
913202010.32641/rchped.v91i3.1607325Prematuritynewbornlow birth weightrenal functionarterial hypertensionchronic kidney disease
Palabras clave:Prematuridad; recién nacido; bajo peso de nacimiento; función renal; hipertensión arterial; enfermedad renal crónicaResumenEl recién nacido prematuro se enfrenta a las condiciones extrauterinas con sistemas aún inmaduros, tanto anatómica como fisiológicamente. El riñón termina de desarrollarse a finales del tercer trimestre del embarazo, por lo que está especialmente expuesto a alterar su desarrollo normal en caso de nacer en forma prematura. Esta situación puede condicionar, entre otras consecuencias, una menor masa renal funcional y cambios microvasculares que representan un riesgo elevado de hipertensión arterial y daño renal crónico en el largo plazo. En el presente artículo se analiza la evidencia existente actual sobre estos riesgos en los prematuros y se ofrece un esquema de seguimiento de estos niños desde el punto de vista nefrológico.AbstractThe premature newborn faces extrauterine conditions with some systems still immature, both anatomically and physiologically. The kidney finishes developing at the end of the third trimester of pregnancy, so it is especially exposed to alter its normal development if preterm birth occurs. This situation may condition, among other consequences, a lower functional renal mass and microvascular changes comprising a high risk of chronic kidney disease in the long term and arterial hypertension. This article analyzes the current evidence on these risks in premature infants and offers a nephrology follow-up scheme of these children.¿Qué se sabe del tema que trata este estudio?El desarrollo anatómico y funcional de nuestros órganos puede verse alterado cuando el nacimiento ocurre en forma prematura. Con relación a esta situación, el riñón humano puede no lograr desarrollar una masa nefronal completa si nace muy prematuro, y por ende más susceptible de daño renal crónico.¿Qué aporta este estudio a lo ya conocido?La evidencia científica actual demuestra que el riñón del niño prematuro es más propenso a desarrollar un daño crónico a futuro, así como hipertensión arterial como coadyuvante de riesgo cardiovascular. Estos hechos hacen necesario un seguimiento de largo plazo de función renal y presión arterial en este grupo de niños/as.
Introducción
El nacimiento prematuro, definido como aquel que ocurre antes de las 37 semanas de edad gestacional (EG) es un evento desafortunadamente frecuente. La incidencia global de partos prematuros es de aproximadamente el 10%, siendo más alta en países en vías de desarrollo [1][2][3] . En Chile esta cifra alcanza al 7% 3 . Las causas de partos prematuros en países de altos ingresos se relacionan a avanzada edad materna, obesidad materna, reproducción asistida, gestaciones múltiples y enfermedades crónicas en la gestante, en cambio, en países de bajos ingresos la maternidad en adolescentes, desnutrición materna, preeclampsia, infecciones maternas y pobreza son las causas más frecuentes 1 . La prematurez, a su vez, es la principal causa de mortalidad neonatal, especialmente en países de bajos ingresos 4 , y un importante factor de discapacidad futura 1 .
Si bien inicialmente los esfuerzos médicos en este grupo de recién nacidos (RN) estaba enfocado en aumentar su supervivencia, el avance del desarrollo tecnológico y del conocimiento de la fisiología fetal nos han permitido preocuparnos de lograr una sobrevida sin secuelas funcionales derivadas de la propia inmadurez o de las terapias empleadas. Los conocimientos actuales nos han mostrado que el desarrollo madurativo de algunos sistemas, tanto anatómico como funcional, puede completarse en las últimas semanas del embarazo de término, como ocurre con el riñón 5,6 . En condiciones de prematurez, esta madurez morfo-funcional del tejido renal puede no ocurrir y, teóricamente, puede derivar en una situación fisiopatológica que genere un daño acumulativo que se exprese en etapas posteriores de la vida. El presente artículo explora la evidencia científica actual relacionada a los posibles efectos futuros sobre el riñón y su función, en el contexto de haber nacido prematuro y/o con bajo peso de nacimiento (BPN).
Desarrollo renal prenatal y post natal precoz
La nefrogénesis, y específicamente la glomerulogénesis, ocurren intrauterinamente desde la semana 9 hasta la semana 34 a 36 de EG, con más del 60% de los nefrones siendo formados en el último trimestre del embarazo 2,6 . Este desarrollo sigue un sentido centrífugo, en el que los glomérulos más nuevos van apareciendo en las capas más externas de la corteza y los más antiguos van quedando en regiones más profundas. La producción de orina fetal se inicia a las 9-10 semanas de EG y formará un significativo componente del volumen de líquido amniótico 7,8 . Debido a la alta resistencia vascular fetal intrauterina, el flujo sanguíneo renal y, por ende, la velocidad de filtración glomerular (VFG), es baja 8 . En niños de término, el número de nefrones al nacer es muy variable, y va de 210.000 hasta 2,7 millones, un número muy relacionado al peso de nacimiento y a la EG 9 . La dotación o masa nefronal que se alcance en ese momento será con la que un individuo afronta el resto de su vida. Una excepción a esto ocurre en RN muy prematuros, en los que la nefrogénesis puede continuar en la vida extrauterina por 40 días más, siempre que el ambiente que rodea al niño y su situación clínica sean óptimos, lo que incluye buena hemodinamia y oxigenación, nutrición adecuada y evitar nefrotóxicos 10 . Algunos de estos nuevos nefrones son anormales y envejecen en forma acelerada 7,11 . Si el RN prematuro sobrevive con una disminución marcada del número de nefrones por la detención de la nefrogénesis intra o extra útero, se aplica el concepto de "oligonefropatía del prematuro" congénita o adqui-
Riesgos a largo plazo
En el análisis de complicaciones renales a largo plazo es importante recalcar que la mayoría de los estudios al respecto adolecen de tener un período de seguimiento relativamente corto, debido especialmente a que la mayor sobrevida de RN muy prematuros, población de alto riesgo de secuelas, es una realidad de décadas recientes 1,2,9,13 . Las complicaciones renales agudas, mejor estudiadas, se relacionan principalmente a inmadurez en la función tubular (tubulopatía del prematuro) y comprenden problemas relacionados a inadecuado manejo del agua libre, desbalance electrolítico y ácido-base, y pérdidas excesivas de minerales y proteínas 14 .
De las posibles complicaciones a largo plazo es importante destacar (figura 1):
a. Hipertensión arterial
La asociación entre RN prematuro y presión arterial (PA) más elevada parece estar bien establecida, aunque no claramente como hipertensión arterial (HTA), para lo cual podría requerirse más tiempo de seguimiento 1,2,13,15 . En el caso de adolescentes y adultos jóvenes nacidos prematuramente varios estudios han observado mayores tasas de PA elevada e HTA, e inversamente proporcional a la prematurez del nacimiento 16,17 . En un pequeño estudio local en escolares nacidos muy prematuramente (menores de 32 sema-nas EG o menos de 1.500 g al nacer), el registro de monitoreo ambulatorio de PA (MAPA) demostró una alta prevalencia de alteraciones, principalmente la ausencia de diferencia de PA día vs noche, lo que se relaciona con mayor riesgo de progresión a HTA 18 .
Un estudio de metaanálisis reciente encontró que las PA sistólica y diastólica fueron en promedio 3,4 mmHg y 2,1 mmHg más elevadas, respectivamente, en adultos jóvenes nacidos en forma prematura, comparado con sus pares nacidos a término 16 . Otro estudio similar cifró esta diferencia en 4,2 mmHg para la PA sistólica y 2,6 mmHg para la PA diastólica 19 . Un tercer estudio evaluó el efecto futuro de ser RN pequeño (PEG) vs adecuado (AEG) para la EG en relación a cifras tensionales en adultos, mostrando un PA sistólica 7,2 mmHg mayor en los primeros 20 . Si bien estas diferencias parecen no ser importantes, es claro que conllevan un mayor riesgo cardiovascular; en una población general se calcula que 4 mmHg de diferencia de PA está asociada a una reducción de 20% en la mortalidad por accidentes vasculares encefálicos y a un 15% de menor mortalidad de otras enfermedades vasculares, especialmente en individuos más jóvenes 21 . Interesantemente, mujeres nacidas muy precozmente (< 32 semanas EG) tienen mayor frecuencia de complicaciones del embarazo, con un 50% de aumento en HTA gestacional, pre eclampsia y, aún, HTA crónica 13,15,22 . A su vez, debido a la preeclampsia, hay más partos prematuros, y estos tienen mayor riesgo de PA elevada, cerrando de esta manera un círculo vicioso 13,15,23 . Las posibles causas para este mayor riesgo de HTA en RN prematuros son múltiples, destacando una mayor rigidez de las paredes vasculares por baja densidad de elastina, diámetro aórtico reducido, reducida densidad capilar asociado a un perfil molecular anti-angiogénico, alteraciones vasculares por daño endotelial oxidativo y envejecimiento vascular precoz, mayor sensibilidad al sodio o menor excreción de éste, y factores maternos/gestacionales que condicionan una epigenética de riesgo hipertensógeno 5,13,15,24 . Un exagerado aumento del índice de masa corporal post natal en prematuros también puede llevar a un aumento del riesgo de HTA futura 1,4 .
b. Riesgo de daño renal crónico
La prematuridad extrema, especialmente cuando se asocia a un período postnatal inmediato con patologías graves (ej.: enterocolitis necrotizante, insuficiencia respiratoria) induce a una oligonefropatía del prematuro, a lo cual pueden agregarse otro tipo de factores que aumenten el daño renal futuro como asfixia neonatal, drogas nefrotóxicas, sepsis y nefrocalcinosis 1,2,13 . De este modo, y de acuerdo a la hipótesis de Brenner, los cambios hemodinámicos adaptativos en un número reducido de glomérulos producen una hipertensión glomerular, glomerulomegalia y finalmente glomeruloesclerosis 25 . Un metaanálisis, que incluyó más de 2 millones de individuos de 31 estudios, encontró que el bajo peso de nacimiento estuvo asociado con aproximadamente un 80% de aumento de probabilidad de albuminuria, un 80% de disminución sostenida de la VFG y un 60% de mayor probabilidad de daño renal crónico terminal en etapas posteriores de la vida, cuando comparado con individuos nacidos con peso normal 26 . Otro estudio noruego que analizó esta asociación en el registro clínicos de un gran número de individuos concluyó que existe un riesgo relativo de 1,78 de desarrollar falla renal crónica terminal en todos los niños con peso de nacimiento menor que el percentil 10 27 . Un reciente estudio de caso-control en niños japoneses con desarrollo de daño renal crónico durante la niñez encontró que un 21% de los casos eran atribuibles a BPN y existió una fuerte correlación entre prematurez y daño renal crónico 28 . Un elemento confundente en muchos de estos análisis es la falta de definición del concepto "Bajo peso de nacimiento", en el cual podemos tener RN prematuros con bajo o adecuado peso para la edad gestacional, así como RN de término pero PEG (retraso de crecimiento intrauterino). Hay evidencia publicada en relación que, a igual prematurez al nacer, la VFG y la reserva funcional renal en etapas posteriores es más baja en los nacidos PEG vs AEG 1 . Otro factor que también puede alterar esta asociación es la forma en que estos prematuros sobrevivieron a sus primeros meses de vida, incluyendo patologías graves, uso de nefrotóxicos e inadecuada nutrición postnatal.
c. Otros riesgos
Es probable que un paciente con sospecha de oligonefropatía del prematuro esté más expuesto a desarrollar una progresión más rápida hacia el daño renal crónico si es afectado por impactos adicionales como insuficiencia renal aguda, glomerulonefritis o condiciones que conlleven riesgo de daño renal como diabetes, obesidad o hipertensión arterial 13,29 . Entre las patología estudiadas que progresan más rápidamente si el paciente tuvo un bajo peso de nacimiento están la nefropatía por IgA, la nefropatía membranosa, la enfermedad por cambios mínimos, la glomeruloesclerosis focal y segmentaria, la enfermedad renal poliquística autosómica dominante y el síndrome de Alport 13 . En niños con síndrome nefrótico idiopático, un estu-dio mostró un peor daño histológico en aquellos niños nacidos con bajo peso de nacimiento 30 . De hecho, se encontró un mayor porcentaje de glomeruloesclerosis focal y segmentaria córtico resistente en este grupo; y de los niños córtico sensibles, aquellos con BPN tenían un curso de enfermedad más severa, caracterizado por córtico dependencia y uso más frecuente de drogas inmunosupresoras adicionales. Estos datos sugieren un rol condicionante de cambios hemodinámicos y podocitarios debido a una reducida masa nefronal en BPN 30 .
Otra complicación renal frecuente en los prematuros es el desarrollo de nefrocalcinosis, sugiriendo una maduración diferenciada de los túbulos renales expresando hipercalciuria e hipocitraturia 2 y un lento flujo de orina que facilitaría el depósito de cristales de calcio, riesgo que aumenta por el uso de furosemida, aminoglicósidos, corticoides y nutrición parenteral 1 .
Seguimiento nefrológico de recién nacidos prematuros
Los pediatras que hacen el seguimiento clínico de estos niños, especialmente los muy prematuros, deben tener una alta sospecha de detección de disfunción renal dados los antecedentes expuestos. Si bien el antecedente de prematurez o BPN puede ser fácilmente obtenido de su registro clínico, muchas veces los eventos de daño renal agudo durante el período neonatal son escasamente documentados 1 . Como recomendaciones generales para preservar función renal en este grupo de niños están: • Incluir historia perinatal en anamnesis a cualquier edad. • Aconsejar que eviten potenciales nefrotóxicos (ej.
antiinflamatorios no esteroidales, aminoglicósidos) y otros factores agravantes (deshidratación, infecciones urinarias). • Mantener la PA bien controlada. Adecuar dieta sana, especialmente bajo consumo de sal. • Promover lactancia materna. • Reducir otros factores de riesgo de enfermedad renal crónica, incluyendo obesidad, diabetes y dislipidemia. • Para los potenciales donantes vivos de riñón, cautela porque tienen mayor susceptibilidad de disfunción renal en el riñón remanente.
En forma más dirigida, el seguimiento clínico debe estructurarse de acuerdo a mayor o menor riesgo de desarrollar una enfermedad renal crónica a futuro (figura 2). Idealmente, esto debiera estar inserto en un programa específico, con la participación de pediatras y nefrólogos pediátricos con distintos grados de intervención según riesgo asignado. De no contar con el recurso del subespecialista, se debe definir la derivación a éste en casos de PA mayor a percentil 95 en forma sostenida, presencia de microalbuminuria o proteinuria patológica, elevación de biomarcadores de disfunción renal (ej. creatinina), y ecografía renal y vesical alterada. Para aquellos niños mayores de 5 años, en que las cifras de PA pueden estar influenciadas por el stress de la consulta médica (HTA de delantal blanco) se recomienda uso de MAPA.
Conclusiones
El enfrentamiento clínico de niños que han nacido en forma prematura requiere de un conocimiento del desarrollo anátomo-fisiológico del niño por nacer, y de las consecuencias posibles a largo plazo cuando ese proceso madurativo se afecta, se acelera o no se completa. En el caso del riñón, la prematuridad y el BPN, especialmente cuando el período neonatal presenta pa-tologías serias, se asocia a cifras elevadas de PA y a riesgo aumentado de enfermedad renal crónica en la etapa adulta, además de una progresión más acelerada o severa en algunas patologías renales no relacionadas con la prematurez. Este riesgo parece ser amplificado si se le suma una restricción del crecimiento intrauterino. Información más concreta en este tema vendrá cuando se realicen estudios en adultos mayores nacidos en forma prematura. En este contexto, es perentorio hacer un seguimiento cercano y prolongado, tanto clínico como de laboratorio, en aquellos niños nacidos antes de término, especialmente en aquellos niños muy prematuros (< 32 semanas EG), de muy BPN (< 1.500 g) o con factores de riesgo renal asociado.
Conflicto de intereses
El autor declara no tener conflicto de intereses. Figura 2. Algoritmo de seguimiento clínico de niños con bajo peso de nacimiento. cys c: cistatina c; creat: creatininemia; dRA: daño renal agudo; HtA: hipertensión arterial; iMc: índice de masa corporal; MAPA: monitoreo ambulatorio de presión arterial; MAu: microalbuminuria; PA: presión arterial; PEG: pequeño para edad gestacional; Rciu: retraso de crecimiento intrauterino; uciN: unidad de cuidados intensivos neonatales; ucreat: creatininuria; uprot: proteinuria.
Figura 1 .
1Esquema de la progresión del daño renal en prematuros. BPN: bajo peso de nacimiento, uciN: unidad de cuidados intensivos Neonatales.
rida, respectivamente2,8 . Esto puede conducir a riñones de menor tamaño aunque generalmente con igual velocidad de filtración glomerular (VFG) que un niño de término de igual edad, debido a un estado de hiperfiltración de cada glomérulo remanente. Para lograr esta hiperfiltración, los glomérulos usualmente aumentan de tamaño (glomerulomegalia)11,12 .
Riñón en el prematuro -F. cavagnaro SM
Preterm birth and its impact on renal health. V Luyckx, Semin Nephrol. 37Luyckx V. Preterm birth and its impact on renal health. Semin Nephrol 2017;37: 311-9.
Peso al nacer y su repercusión nefrológica. P Ortega, I Zamora, NefroPlus. 4Ortega P, Zamora I. Peso al nacer y su repercusión nefrológica. NefroPlus 2011;4:1-10.
Epidemiología de la prematuridad, sus determinantes y prevención del parto prematuro. L A Mendoza, D Claros, L I Mendoza, M Arias, C Peñaranda, Rev Chil Obstet Ginecol. 81Mendoza LA, Claros D, Mendoza LI, Arias M, Peñaranda C. Epidemiología de la prematuridad, sus determinantes y prevención del parto prematuro. Rev Chil Obstet Ginecol 2016;81:330-42.
Preterm birth: long term cardiovascular and renal consequences. H Chehade, U Simeoni, J P Guignard, F Boubred, Current Pediatric Review. 14Chehade H, Simeoni U, Guignard JP, Boubred F. Preterm birth: long term cardiovascular and renal consequences. Current Pediatric Review 2018;14:219-26.
Adult consequences of extremely preterm birth. Cardiovascular and metabolic diseases risk factors, mechanism, and prevention avenues. A Nuyt, J C Lavole, Mohamed I Paquette, K Luu, T , Clin Perinatol. 44Nuyt A, Lavole JC, Mohamed I, Paquette K, Luu T. Adult consequences of extremely preterm birth. Cardiovascular and metabolic diseases risk factors, mechanism, and prevention avenues. Clin Perinatol 2017;44:315-32.
Management of the fetus with congenital hydronephrosis. M Harrison, M Golbus, R Filly, J Ped Surg. 17Harrison, M, Golbus M, Filly R, et al. Management of the fetus with congenital hydronephrosis. J Ped Surg 1982;17:728- 42.
Preterm birth and the kidney: implications for long-term renal health. L Gubhaju, M Sutherland, M J Black, Reprod Sci. 18Gubhaju L, Sutherland M, Black MJ. Preterm birth and the kidney: implications for long-term renal health. Reprod Sci 2015;18:322-33.
Assesment of kidney function in preterm infants: lifelong implications. C Abitbol, M Defreitas, J Strauss, Pediatr Nephrol. 31Abitbol C, DeFreitas M, Strauss J. Assesment of kidney function in preterm infants: lifelong implications. Pediatr Nephrol 2016;31:2213-22.
Prematurity and future kidney health: the growing risk of chronic kidney disease. M Starr, S Hingorani, Curr Opin Pediatr. 30Starr M, Hingorani S. Prematurity and future kidney health: the growing risk of chronic kidney disease. Curr Opin Pediatr 2018;30:228-35.
Histomorphometric analysis of postnatal glomerulogenesis in extremely preterm infants. M Rodríguez, A Gómez, C Abitbol, J Chandar, S Duara, G Zilleruelo, Pediatr Dev Pathol. 7Rodríguez M, Gómez A, Abitbol C, Chandar J, Duara S, Zilleruelo G. Histomorphometric analysis of postnatal glomerulogenesis in extremely preterm infants. Pediatr Dev Pathol 2004;7:17-25.
Accelerated maturation and abnormal morphology in the preterm neonatal kidney. M Sutherland, L Gubhaju, L Moore, J Am Soc Nephrol. 22Sutherland M, Gubhaju L, Moore L, et al. Accelerated maturation and abnormal morphology in the preterm neonatal kidney. J Am Soc Nephrol 2011;22:1365- 74.
Extra uterine development of preterm kidneys. Y Kandasamy, D Rudd, R Smith, E Lumbers, I Wright, Pediatr Nephrol. 33Kandasamy Y, Rudd D, Smith R, Lumbers E, Wright I. Extra uterine development of preterm kidneys. Pediatr Nephrol 2018;33:1007-12.
The low birth weight and nephron number working group. The impact of kidney development on the life course: a consensus document action. Nephron. 136The low birth weight and nephron number working group. The impact of kidney development on the life course: a consensus document action. Nephron 2017;136:3-49.
Renal consequences of preterm birth. A Stritzke, S Thomas, H Amin, C Fusch, A Lodha, 10.1186/s40348-016-0068-0Mol Cell Pediatr. 42Stritzke A, Thomas S, Amin H, Fusch C, Lodha A. Renal consequences of preterm birth. Mol Cell Pediatr 2017; 4:2. doi: 10.1186/s40348-016-0068-0.
Preterm birth and hypertension: Is there a link?. M Bertagnolli, Mai Luu, T Lewandowski, A Leeson, P Nuyt, A , doi: 10.1007/ s11906-016-0637-6Curr Hypertens Rep. 1828Bertagnolli M, Mai Luu T, Lewandowski A, Leeson P, Nuyt A. Preterm birth and hypertension: Is there a link? Curr Hypertens Rep 2106;18:28. doi: 10.1007/ s11906-016-0637-6.
Blood pressure in young adults born at very low birth weight. P Hovi, B Vohr, L Ment, Hypertension. 68Hovi P, Vohr B, Ment L, et al. Blood pressure in young adults born at very low birth weight. Hypertension 2016;68:880-7.
Renal function and blood pressure are altered in adolescents born preterm. A South, P Nixon, M Chappell, Pediatr Nephrol. 34South A, Nixon P, Chappell M, et al. Renal function and blood pressure are altered in adolescents born preterm. Pediatr Nephrol 2018;34:137-44.
Monitorización ambulatoria de presión arterial en escolares con antecedentes de prematurez extrema. A Solís, J Cerda, C González, Rev Chil Pediatr. 89Solís A, Cerda J, González C. Monitorización ambulatoria de presión arterial en escolares con antecedentes de prematurez extrema. Rev Chil Pediatr 2018;89:18-23.
Preterm birth and metabolic syndrome in adult life: a systematic review and meta-analysis. J R Parkinson, M Hyde, C Gale, S Santhakumaran, N Mosi, Pediatrics. 131Parkinson JR, Hyde M, Gale C, Santhakumaran S, Mosi N. Preterm birth and metabolic syndrome in adult life: a systematic review and meta-analysis. Pediatrics 2013;131:e1240-e1263.
Effect of birth weight on life-course blood pressure levels among childrenborn premature: the Cardiovascular Risk in Young Finnis Study. M Juonala, M Cheung, M Sabin, J Hypertens. 33Juonala M, Cheung M, Sabin M, et al. Effect of birth weight on life-course blood pressure levels among childrenborn premature: the Cardiovascular Risk in Young Finnis Study. J Hypertens 2015;33:1542-8.
Effects of blood pressure reduction in mild hypertension: a systematic review and meta-analysis. J Sundstrom, H Arima, R Jackson, Ann Intern Med. 162Sundstrom J, Arima H, Jackson R, et al. Effects of blood pressure reduction in mild hypertension: a systematic review and meta-analysis. Ann Intern Med 2015;162:184-91.
Pregnancy complications among women born preterm. A Boivin, Z C Luo, F Audibert, CMAJ. 184Boivin A, Luo ZC, Audibert F, et al. Pregnancy complications among women born preterm. CMAJ 2012;184:1777-84.
Cardiovascular risk in children and young adults born to preeclamptic pregnancies: a systematic review. E Davis, M Lazdam, A Lewandowski, S Worton, Pediatrics. 129Davis E, Lazdam M, Lewandowski A, Worton S, et al. Cardiovascular risk in children and young adults born to preeclamptic pregnancies: a systematic review. Pediatrics 2012;129:e1552-61.
Functional role of epigenetic regulation in the development of prenatal programmed hypertension. Y Liu, M Liang, Kidney Int. 96Liu Y, Liang M. Functional role of epigenetic regulation in the development of prenatal programmed hypertension. Kidney Int 2019;96:8-12.
Congenital oligonephropathy: an inborn cause of adult hypertension and progressive renal injury?. B M Brenner, G M Chertow, Curr Opin Nephrol Hypertens. 2Brenner BM, Chertow GM. Congenital oligonephropathy: an inborn cause of adult hypertension and progressive renal injury? Curr Opin Nephrol Hypertens 1993;2:691-5.
Is low birth weight an antecedent of CKD in later life? A systematic review of observational studies. S L White, V Perkovic, A Cass, Am J Kidney Dis. 54White SL, Perkovic V, Cass A, et al. Is low birth weight an antecedent of CKD in later life? A systematic review of observational studies. Am J Kidney Dis 2009;54:248-61.
Low birth weight increases risk for endstage renal disease. B Vikse, Irgensl, T Leivestad, J Am Soc Nephrol. 19Vikse B, IrgensL, Leivestad T, et al. Low birth weight increases risk for end- stage renal disease. J Am Soc Nephrol 2008;19:151-7.
Association between low birth weight and childhood onset chronic kidney disease and the National Vital Statistics Report. D Hirano, K Ishikura, O Uemura, Nephrol Dial Transplant. 31Hirano D, Ishikura K, Uemura O, et al. Association between low birth weight and childhood onset chronic kidney disease and the National Vital Statistics Report. Nephrol Dial Transplant 2016;31:2119-26.
The long-term renal and cardiovascular consequences of prematurity. C Abitbol, M Rodríguez, Nat Rev Nephrol. 8Abitbol C, Rodríguez M. The long-term renal and cardiovascular consequences of prematurity. Nat Rev Nephrol 2012;8:265-74.
Low birth weight is a conditioning factor for podocyte alteration and steroid dependence in children with nephrotic syndrome. G Conti, De Vivo, D Fede, C , Journal of Nephrology. 31Conti G, De Vivo D, Fede C, et al. Low birth weight is a conditioning factor for podocyte alteration and steroid dependence in children with nephrotic syndrome. Journal of Nephrology 2018;31:411-5.
| [
-0.06096665933728218,
0.02344161458313465,
0.06071748584508896,
0.012781401164829731,
-0.023561174049973488,
0.036026205867528915,
-0.111172616481781,
0.15156729519367218,
0.05861770361661911,
0.16216711699962616,
0.1298287808895111,
-0.12010654807090759,
-0.032273098826408386,
-0.04073273... |
Fang Cai 6642103@qq.com
College of Foreign Languages
Liaoning Institute of Science and Engineering
JinzhouChina
Corresponding Author
410.25236/FER.2021.040808Published by Francis Academic Press, UK -38-Research on Improving English Writing Ability by Lexical Chunks ApproachLexical chunks approachEnglish writingProblemsAdvantagesCountermeasures
As a whole linguistic unit, lexical chunks have the characteristics of prefabrication and extraction. Based on the relevant theories, this paper analyzes the existing problems in English writing teaching, expounds the advantages of lexical chunks in improving English writing ability, and puts forward some countermeasures to improve English writing ability .The problems include: the obsolete teaching mode of English writing, the influence of negative cultural transfer, the neglect of cultural infiltration in the process of writing, and the students' poor basic knowledge of English. The advantages include: reducing the negative transfer of mother tongue in writing, improving the fluency of English writing, quickly building the overall framework of the article, and improving the coherence and logic of the article. The countermeasures include: accumulating and enriching lexical chunks through various channels, paying attention to the cultural connotations contained in lexical chunks, training students' lexical chunks identification ability, strengthening the combination of lexical chunks and mind map, and improving students' autonomous learning ability of English lexical chunks.
Introduction
Writing is one of the most important contents of English teaching. This paper starts with the analysis of the characteristics of English words, sentences, paragraphs and articles, so that students can master the characteristics of words, sentence structure, paragraphs and chapters. Through the reading and writing practice of model essays, students can systematically master the basic knowledge and skills of English writing, skillfully write all kinds of English practical essays and improve their written expression ability. They also strive to achieve the accuracy of words, correct grammar, and expression in line with English habits.
The memory, storage, output and use of language are not based on a single word, but on a fixed or semi fixed block structure. Lexical chunk is a fixed or semi fixed combination of multiple words according to a certain grammar. Lexical chunks, which combine the advantages of grammar, semantics and context, play an important role in foreign language learning [1]. The purpose of lexical chunks teaching is to improve students' sensitivity to "chunking" and cultivate their ability to use lexical chunks through the cycle of "observation, hypothesis and verification". Lexical chunks approach takes chunk as the core of teaching. It not only pays attention to grammatical structure, but also pays attention to the application in specific context. It follows the idea that the composition of language is grammaticalized vocabulary, not lexicalized grammar. At the same time, students' attention should be shifted from word learning to lexical chunk learning. The lexical chunk learning should be used to build a language network, not just to explain and translate the target language, so as to give full play to students' subjective initiative.
As a whole linguistic unit, lexical chunks have the characteristics of prefabrication and extraction. The purpose of writing ability training is to help students input a large number of lexical chunks to ensure that they can be extracted in a short time when necessary. A large number of lexical chunks stored in the brain can help to reduce the decoding pressure, shorten the output time and improve the fluency of language expression. A word block could be producible, which means that a lexical chunk could produce some words of the same attribute within the same type. When students memorize the relevant lexical chunks within a certain range, they will also remember the lexical chunks related to this lexical chunk group [2].Therefore, in the process of writing, language output can be expanded better. Lexical chunks approach has changed the traditional teaching mode of writing and plays an important
Theoretical Basis
The Dual System Theory of Language
Skehan and Wary put forward the dual system theory of language. First, language is a rule-based analysis system, which is composed of a large number of words and grammar, relatively closed and fixed. Second, language is a system of formulas based on memory, which is composed of lexical chunks with communicative functions and relatively open and flexible. The former is mainly short-term memory, which is abstract and difficult to extract. The latter is mainly about long-term memory and more specific, which could be quickly extracted from the memory to meet the needs of instant communication, making the language fluent and accurate. These two systems complement each other and are indispensable elements in language. The formulaic system based on memory is composed of chunks. If we master chunks, we can save time and effort in language output.
Cognitive Psychology Theory
Cognitive psychology studies people's advanced psychological process. It is concerned about the psychological mechanism as the basis of human behavior. It is mainly the cognitive process, including attention, perception, representation, memory, thinking and speech. The core is the internal psychological process between information input and output. Lexical chunk use involves many psychological cognitive factors, the most important of which is working memory. Working memory is used for the temporary storage and preliminary screening of language information, and then to establish a connection with the retrieval or extraction of relevant information from long-term memory, so as to provide a reference for language information processing. Students absorb, collect and store a large number of lexical chunks from the input of language information, which are solidified in long-term memory after repeated cognition and memory [3].
Information Processing Theory
According to information processing theory, cognitive process is the process of information processing. From short-term memory to long-term memory, information has undergone a critical change, which needs to go through the coding process. Coding is not to gather relevant information together, but to organize information in various ways. From the point of view of information processing, students should input, store, code and extract the words in the process of learning, and guide them to establish the emotional network between the words, including broad processing and deep processing, so as to improve their comprehension and written expression ability. The closer the network is connected, the faster the information would be activated and extracted.
Problems in English Writing Teaching
The Obsolete Teaching Mode of English writing
Teaching mode is a stable and concise theoretical model of teaching structure and a practical activity mode of its specific operation formed around a certain theme under the guidance of certain teaching ideas and rich teaching experience in order to achieve specific teaching objectives and contents. The traditional English teaching mode lacks guidance for students. The writing process is just a simple process of material translation. It lacks dialogue and collision of views, creative thinking and internalization of knowledge. At the same time, it cannot stimulate students' interest in writing and creative thinking. The motivation and creativity of writing are suppressed [4].
The Influence of Negative Cultural Transfer Cannot be Eliminated
Due to the interference and influence of the mother tongue, they rigidly apply the grammatical rules and language habits of English and have no clear understanding of the meaning of English words. Besides, they do not really grasp the connotation of vocabulary, and lack the ability to use vocabulary flexibly. In the process of writing, students just express the logical relationship and omit the transition words. What's more, the thinking modes of the two languages are different. English emphasizes Published by Francis Academic Press, UK -40-hypotaxis. The logical relationship between sentence elements depends on the expression of connectives, and the sentence structure is rigorous. However, Chinese emphasizes parataxis, and there is implicit logical relationship between sentence elements. The sentence structure is relatively loose due to less use of related words.
The Neglect of Cultural Infiltration in the Process of Writing
Language learners should not only learn the language form, but also the cultural connotation, that is the language in culture and the culture in language. Cultural differences may cause misunderstanding in language communication [5]. At present, English writing teaching only pays attention to the correctness of language. Teachers focus on teaching language knowledge points, but rarely give real language environment, rarely analyze language differences on the cultural level. Although students have a good grasp of vocabulary and grammar knowledge, they always use Chinese thinking habits to express themselves in English. As a result, their writing level is difficult to improve.
The Students' Poor Basic Knowledge of English
The basic knowledge of English directly affects the writing level, and many students' basic knowledge of English is not solid [6]. For example, first, there are always some differences between the former and the latter, mainly reflected in the mixed use of "you" and "we". Second, the tenses are often used include past tense, present tense, progressive tense and perfect tense. Third, the structure of the article and the passage are not clear, and the sentences are not complete. Forth, many relevant words are used in the writing, including "but, besides, for", and so on. Some students don't use relevant words at all. Fifth, some simple sentences, words and sentence patterns are repeated in the writing, which makes the language expression dull.
The Advantages of Lexical Chunks in Improving English Writing Ability
Reduce the Negative Transfer of Mother Tongue in Writing
The biggest difference between mother tongue learning and foreign language learning is that mother tongue learners master a large number of lexical chunks that can be used according to the language environment. When using mother tongue, language knowledge seldom appears in the form of analytic grammar rules, but more in the form of lexical chunks. Lexical chunks can prevent foreign language learners from using them as their mother tongue and fundamentally inhibit Chinglish. Lexical chunks can make learners aware of the cultural differences carried by the language, so as to consciously avoid the negative transfer of mother tongue culture. In the teaching of English writing, students should be aware of the universality and necessity of lexical chunks and use them directly according to the needs of context.
Improve the Fluency of English Writing
Language fluency depends on the amount of chunks stored, not just the grammatical rules and lexical data stored in the brain. Lexical chunks are stored in their own vocabulary as a whole, which can be used quickly without temporary combination in communication. It can reduce the burden of brain coding, save the time of language processing, and achieve the purpose of fluent language use. Only by using a large number of lexical chunks to lighten the burden of memory can we write high-quality articles. Fluency in English writing depends not only on the speed of writing and the agility of thinking, but also on the accumulation and use of lexical chunks [7].
Build the Overall Framework of the Article Quickly
Lexical chunks can effectively express the textual structure in English writing. Therefore, students can use lexical chunks to construct a text, and use lexical chunks to make the text more coherent. Teachers can create writing templates of related topics and genres according to the actual needs of teaching and students' existing knowledge level. For example, the text structure "one day..., then..., next..., finally..." that students summarized can help students describe the course of things, form a good frame structure, speed up the construction of discourse, and make the writing ideas clear and visual.
Improve the Coherence and Logic of the Article.
Whether the content of an article is expressed clearly is directly related to the coherence and logic. Many students write English articles with single sentence structure and loose structure, mainly because they can't use lexical chunks to express cohesion and transition. In order to improve coherence and logicality, students are guided to accumulate lexical chunks representing cohesion and transition in daily teaching. First, the conjunctions of choice or equivalence are either...or, neither...nor, as well as...Second, the conjunctions in chronological order are at first, then, later, at the beginning, in the end...The conjunctions that indicate the conclusion are in a word, in short, to sum up, in all....The use of discourse connectives in sentences and paragraphs serves as a link between the preceding and the following [8].
Lexical Chunks Approach Improves Countermeasures in English Writing Ability
Accumulate and Enrich Lexical Chunks Through Various Channels
According to the relationship between language input and output, quality input can drive quality output. English learning lacks language environment, so students need to consciously accumulate lexical chunks, store them in the brain as a whole, strengthen them regularly, and strengthen the accumulation and mastery. There are two main ways to accumulate lexical chunks: intentional learning and incidental learning. Intentional learning refers to conscious learning, and recitation is an indispensable means. On the basis of strengthening memory, the learned lexical chunks are internalized into psychological lexical chunks. Incidental learning is an effective way to master a large number of vocabulary. In the process of reading or listening, we can acquire a lot of vocabulary knowledge by understanding the rich context and form a mental lexical chunk library.
Pay Attention to the Cultural Connotations Contained in Lexical Chunks
Culture includes language, which is a special cultural phenomenon. Language is the carrier of culture, which contains a nation's unique traditional culture, way of thinking, social psychology, national customs, value orientation and social concept. Language is the main way of human thinking and cultural exchange. The formation of language and the development of culture restrict each other. The connotations of different cultures are embodied in different languages, especially in vocabulary. Language and culture depend on each other. Learning the cultural connotation of lexical chunks can help us to understand lexical chunks more deeply. We can also learn more about the cultural characteristics of English-speaking countries, pay attention to the cultural differences between English and Chinese, lay stress on cultural infiltration, and deeply understand the cultural connotation, so as to avoid misuse of English.
Trainstudents' Lexical Chunks Identification Ability
Lexical chunk recognition is a process of repeated proficiency. After establishing lexical chunk awareness, students need to improve their lexical chunk application ability through training. Lexical chunk recognition training includes four parts: lexical chunk review, lexical chunk discovery, lexical chunk practice and lexical chunk application [9].Lexical chunk application is to train students' ability to use multiple lexical chunks to compose a text. It not only guides students to choose appropriate lexical chunks for combination, but also guides students to pay attention to the use of related words and the adjustment of word order structure in the process of lexical chunk cohesion. It makes students use lexical chunks more smoothly by giving examples, simulating conversations and imitating articles. The training of lexical chunk recognition ability is the process of deepening memory and consolidating understanding in lexical chunk learning. Only by continuously strengthening students' lexical chunk recognition foundation, can we complete the rich accumulation of lexical chunks.
Strengthen the Combination of Lexical Chunks and Mind Map
The mind map directly reflects the thinking process of the human brain. It uses multiple colors of lines and symbols to effectively dig out the right brain function, and reflects the potential functions of vision, comprehensive, divinity and painting [10]. Mind the confusion of thinking in the process of writing to the maximum extent. Mind map can present lexical chunks clearly and intuitively. When encountering compositions similar to this topic in the future, according to the existing writing framework and specific content in the mind, mind map can help students sort out and accumulate lexical chunks in an orderly way, so as to improve the efficiency of applying lexical chunks in the process of language output.
Improvine Students' Autonomous Learning Ability of English Lexical Chunks
There are a large number of lexical chunks in English. It is difficult to master a lot of lexical chunks in the limited classroom time. Therefore, it is necessary to cultivate students' autonomous learning ability and give full play to students' main role in lexical chunks learning. Students are required to consciously accumulate a large number of lexical chunks, consciously cultivate their ability to use lexical chunks and reduce their dependence on teachers. In the stage of independent learning, it would be more efficient to strengthen the learning strategy of lexical chunks and improve the comprehensive sense of use. In terms of time arrangement, it can be divided into long-term, medium-term and short-term plans to guide students to adjust their learning plans and goals at any time. Teachers also should take the initiative to communicate with students, solve the problems they encounter in lexical chunks learning, and guide students to improve their efficiency through cooperative learning. Then, the purpose of this study is to guide students to make a stage summary of lexical chunks learning, find out the characteristics of lexical chunks learning, and quickly expand the number of lexical chunks.
Conclusions
Lexical chunks have the characteristics of integrating grammar, semantics and context, which is the most ideal language teaching unit, playing an important role in the process of language formation and use. Lexical chunks approach has an important influence on English writing. Teachers should establish advanced teaching concepts, cultivate students' awareness of lexical chunks, guide students to identify, accumulate and use lexical chunks, and strengthen the input and output of lexical chunks. In English writing, attention should be paid to the extraction of lexical chunks and the proper use of all kinds of lexical chunks to improve the correctness and effectiveness of the use of lexical chunks. At the same time, we should constantly explore and improve teaching methods, cultivate students' scientific learning methods and good learning habits, strengthen the guidance of writing skills, stimulate students' subjective initiative, and guide students to write fluent and beautiful articles.
map can stimulate the knowledge stored in the mind, open up ideas, enrich the content of writing, enhance the logic of English writing, and improve Frontiers in Educational Research ISSN 2522-6398 Vol. 4, Issue 8: 38-43, DOI: 10.25236/FER.2021.040808 Published by Francis Academic Press, UK -42-
AcknowledgementsThis work is supported by Humanities and social sciences research project of department of education of Liaoning province in 2019 (LGKY13217201904): A Corpus-Based Survey of Lexical Chunks Use in English Writing.
College English intensive reading teaching from perspective of lexical theory and enhancement of English writing proficiency. A B Yu, Journal of Hebei University of Engineering(Social Science Edition). 362A. B. Yu, "College English intensive reading teaching from perspective of lexical theory and enhancement of English writing proficiency," Journal of Hebei University of Engineering(Social Science Edition), vol. 36, no. 2, pp. 86-87+90, 2019.
Application of Mind Mapping-based Lexical Approach to English Writing Teaching in Senior High School. D N Fang, Chongqing Normal UniversityMaster's thesis ofD. N. Fang, "Application of Mind Mapping-based Lexical Approach to English Writing Teaching in Senior High School," Master's thesis of Chongqing Normal University, 2018.
Lexical Chunks Theories and College English Teaching. X L Wang, L Huang, College English Teaching & Research. 183X. L. Wang, L. Huang, "Lexical Chunks Theories and College English Teaching," College English Teaching & Research, vol. 18, no. 3, pp. 125-128, 2019.
Analysis on the Application. X S Yang, Overseas English. 2118X. S. Yang, "Analysis on the Application," Overseas English, vol. 21, no. 18, pp. 177-178, 2020.
Improve the English writing level in the cultural infiltration. X P Wang, Educational Practice and Research. 3611X. P. Wang, "Improve the English writing level in the cultural infiltration," Educational Practice and Research, vol. 36, no. 11, pp. 48-49, 2014.
Some problems and ideas of English writing teaching in higher vocational colleges. A B Yu, Modern Economic Information. 3414A. B. Yu, "Some problems and ideas of English writing teaching in higher vocational colleges," Modern Economic Information, vol. 34, no. 14, pp. 400-401, 2019.
The Cognitive and Psychological Analysis of Lexical Chunks' Function on the Fluency of English Writing. L Liu, Journal of Hubei Radio & Television University. 299L. Liu, "The Cognitive and Psychological Analysis of Lexical Chunks' Function on the Fluency of English Writing," Journal of Hubei Radio & Television University, vol. 29, no. 9, pp. 125-126, 2009.
Language block accumulation helps junior high school students to write English. L Q Chen, 10.25236/FER.2021.040808Francis Academic Press443UKL. Q. Chen, "Language block accumulation helps junior high school students to write English," https://www.fx361.com/page/2020/1102/7168371.shtml, 2021-06-20. Frontiers in Educational Research ISSN 2522-6398 Vol. 4, Issue 8: 38-43, DOI: 10.25236/FER.2021.040808 Published by Francis Academic Press, UK -43-
Study on the Impact of Chunk Teaching in College English to Negative Transfer of Native Language. M Zhou, Journal of Beijing Institute of Graphic Communication. 261M. Zhou, "Study on the Impact of Chunk Teaching in College English to Negative Transfer of Native Language," Journal of Beijing Institute of Graphic Communication, vol. 26, no. 1, pp. 129-131, 2018.
The application and analysis of mind map in English reading. J Liu, The Guide of Science & Education. 1112J. Liu, "The application and analysis of mind map in English reading," The Guide of Science & Education, vol. 11, no. 12, pp. 61-62, 2019.
| [
0.020601412281394005,
0.008047541603446007,
0.18071405589580536,
0.053374048322439194,
-0.07576485723257065,
-0.002452573273330927,
0.055627111345529556,
0.04816849157214165,
0.01761167123913765,
0.08726426959037781,
0.07366132736206055,
-0.01921926811337471,
0.1757851392030716,
0.01733274... |
A PTAS for Computing the Supremum of Gaussian Processes
22 Feb 2012
Raghu Meka raghu@ias.edu
Institute for Advanced Study
Princeton
A PTAS for Computing the Supremum of Gaussian Processes
22 Feb 2012D26307802707556940861BC3A5BA692EarXiv:1202.4970v1[cs.DS]
We give a polynomial time approximation scheme (PTAS) for computing the supremum of a Gaussian process.That is, given a finite set of vectorsdeterministically in time poly(d)•|V | Oε(1) .Previously, only a constant factor deterministic polynomial time approximation algorithm was known due to the work of Ding, Lee and Peres [DLP11].This answers an open question of Lee [Lee10] and Ding [Din11].The study of supremum of Gaussian processes is of considerable importance in probability with applications in functional analysis, convex geometry, and in light of the recent breakthrough work of Ding, Lee and Peres [DLP11], to random walks on finite graphs.As such our result could be of use elsewhere.In particular, combining with the recent work of Ding [Din11], our result yields a PTAS for computing the cover time of bounded degree graphs.Previously, such algorithms were known only for trees.Along the way, we also give an explicit oblivious linear estimator for semi-norms in Gaussian space with optimal query complexity.
Introduction
The study of supremum of Gaussian processes is a major area of study in probability and functional analysis as epitomized by the celebrated majorizing measures theorem of Fernique and Talagrand (see [LT91], [Tal05] and references therein).There is by now a rich body of work on obtaining tight estimates and characterizations of the supremum of Gaussian processes with several applications in analysis [Tal05], convex geometry [Pis99] and more.Recently, in a striking result, Ding, Lee and Peres [DLP11] used the theory to resolve the Winkler-Zuckerman blanket time conjectures [WZ96], indicating the usefulness of Gaussian processes even for the study of combinatorial problems over discrete domains.
Ding, Lee and Peres [DLP11] used the powerful Dynkin isomorphism theory and majorizing measures theory to establish a structural connection between the cover time (and blanket time) of a graph G and the supremum of a Gaussian process associated with the Gaussian Free Field on G.They then use this connection to resolve the Winkler-Zuckerman blanket time conjectures and to obtain the first deterministic polynomial time constant factor approximation algorithm for computing the cover time of graphs.This latter result resolves an old open question of Aldous and Fill (1994).
Besides showing the relevance of the study of Gaussian processes to discrete combinatorial questions, the work of Ding, Lee and Peres gives evidence that studying Gaussian processes could even be an important algorithmic tool; an aspect seldom investigated in the rich literature on Gaussian processes in probability and functional analysis.Here we address the corresponding computational question directly, which given the importance of Gaussian processes in probability, could be of use elsewhere.In this context, the following question was asked by Lee [Lee10] and Ding [Din11].
Question 1.1.For every ε > 0, is there a deterministic polynomial time algorithm that given a set of vectors v 1 , . . ., v m ∈ R d , computes a (1 + ε)-factor approximation to
E X←N d [sup i | v i , X |] 1 .
We remark that Lee [Lee10] and [Din11] actually ask for an approximation to E X←N d [sup i v i , X ] (and not the supremum of the absolute value).However, this formulation results in a somewhat artificial asymmetry and for most interesting cases these two are essentially equivalent: if
E X←N d [sup i v i , X ] = ω(max i v i 2 ), then E X←N d [sup I | v i , X |] = (1+o(1)) E X←N d [sup i v i , X ] 2 .
We shall overlook this distinction from now on.
There is a simple randomized algorithm for the problem: sample a few Gaussian vectors and output the median supremum value for the sampled vectors.This however, requires O(d log d/ε2 ) random bits.Using Talagrand's majorizing measures theorem, Ding, Lee and Peres give a deterministic polynomial time O(1)-factor approximation algorithm for the problem.This approach is inherently limited to not yield a PTAS as the majorizing measures characterization is bound to lose a universal constant factor.Here we give a PTAS for the problem thus resolving the above question.
Theorem 1.2.For every ε > 0, there is a deterministic algorithm that given a set of vectors
v 1 , . . . , v m ∈ R d , computes a (1 + ε)-factor approximation to E x←N d [sup i | v i , x |] in time poly(d) • m Õ(1/ε 2 ) .
Our approach is comparatively simpler than the work of Ding, Lee and Peres, using some classical comparison inequalities in convex geometry.
We explain our result on estimating semi-norms with respect to Gaussian measures mentioned in the abstract in Section 2.2.
We next discuss some applications of our result to computing cover times of graphs as implied by the works of Ding, Lee and Peres [DLP11] and Ding [Din11].
Application to Computing Cover Times of Graphs
The study of random walks on graphs is an important area of research in probability, algorithm design, statistical physics and more.As this is not the main topic of our work, we avoid giving formal definitions and refer the readers to [AF], [Lov93] for background information.
Given a graph G on n-vertices, the cover time, τ cov (G), of G is defined as the expected time a random walk on G takes to visit all the vertices in G when starting from the worst possible vertex in G. Cover time is a fundamental parameter of graphs and is extensively studied.Algorithmically, there is a simple randomized algorithm for approximating the cover time -simulate a few trials of the random walk on G for poly(n) steps and output the median cover time.However, without randomness the problem becomes significantly harder.This was one of the motivations of the work of Ding, Lee and Peres [DLP11] who gave the first deterministic constant factor approximation algorithm for the problem, improving on an earlier work of Kahn, Kim, Lovász and Vu [KKLV00] who obtained a deterministic O((log log n) 2 )-factor approximation algorithm.For the simpler case of trees, Feige and Zeitouni [FZ09] gave a FPTAS.
Ding, Lee and Peres also conjectured that the cover time of a graph G (satisfying a certain reasonable technical condition) is asymptotically equivalent to the supremum of an explicitly defined Gaussian process-the Gaussian Free Field on G.However, this conjecture though quite interesting on its own, is not enough to give a PTAS for cover time; one still needs a PTAS for computing the supremum of the relevant Gaussian process.Our main result provides this missing piece, thus removing one of the obstacles in their posited strategy to obtain a PTAS for computing the cover time of graphs.Recently, Ding [Din11] showed the main conjecture of Ding, Lee and Peres to be true for bounded-degree graphs and trees.Thus, combining his result (see Theorem 1.1 in [Din11]) with Theorem 1.2 we get a PTAS for computing cover time on bounded degree graphs with τ hit (G) = o(τ cov (G))3 .As mentioned earlier, previously, such algorithms were only known for trees [FZ09].
Outline of Algorithm
The high level idea of our PTAS is as follows.Fix the set of vectors V = {v 1 , . . ., v m } ⊆ R d and ε > 0. Without loss of generality suppose that max v∈V v 2 = 1.We first reduce the dimension of V by projecting V onto a space of dimension of O((log m)/ε 2 ) á la the classical Johnson-Lindenstrauss lemma (JLL).We then give an algorithm that runs in time polynomial in the number of vectors but exponential in the underlying dimension.Our analysis relies on two elegant comparison inequalities in convex geometry-Slepian's lemma [Sle62] for the first step and Kanter's lemma [Kan77] for the second step.We discuss these modular steps below.
Dimension Reduction
We project the set of vectors V ⊆ R d to R k for k = O((log m)/ε 2 ) to preserve all pairwise (Euclidean) distances within a (1 + ε)-factor as in the Johnson-Lindenstrauss lemma (JLL).We then show that the expected supremum of the projected Gaussian process is within a (1 + ε) factor of the original value.The intuition is that, the supremum of a Gaussian process, though a global property, can be controlled by pairwise correlations between the variables.To quantify this, we use Slepian's lemma, that helps us relate the supremum of two Gaussian processes by comparing pairwise correlations.Finally, observe that using known derandomizations of JLL, the dimension reduction can be done deterministically in time poly(d, m, 1/ε) [EIO02].
Thus, to obtain a PTAS it would be enough to have a deterministic algorithm to approximate the supremum of a Gaussian process in time exponential in the dimension k = O((log m)/ε 2 ).Unfortunately, a naive argument by discretizing the Gaussian measure in R k leads to a run-time of at least k O(k) ; which gives a m O((log log m)/ε 2 ) algorithm.This question was recently addressed by Dadush and Vempala [DV12], who needed a similar sub-routine for their work on computing M-Ellipsoids of convex sets and give a deterministic algorithm with a run-time of (log k) O(k) .Combining their algorithm with the dimension reduction step gives a deterministic m O((log log log m)/ε 2 ) time algorithm for approximating the supremum.We next get rid of this ω(1) dependence in the exponent.
Oblivious Linear Estimators for Semi-Norms
We in fact, solve a more general problem by constructing an optimal linear estimator for semi-norms in Gaussian space.Let ϕ : R k → R + be a semi-norm, i.e., ϕ is homogeneous and satisfies triangle inequality.For normalization purposes, we assume that 1 ≤ E x←N k [ϕ(x)] and that the Lipschitz constant of ϕ is at most k O(1) .Note that the supremum function ϕ V (x) = sup v∈V | v, x | satisfies these conditions.Our goal will be to compute a (1 + ε)-factor approximation to
E x←N k [ϕ(x)] in time 2 Oε(k) .
Theorem 2.1.For every ε > 0, there exists a deterministic algorithm running in time (1/ε) O(k) and space poly(k, 1/ε) that computes a (1 + ε)-factor approximation to E X←N k [ϕ(X)] using only oracle access to ϕ.
Our algorithm has the additional property of being an oblivious linear estimator: the set of query points does not depend on ϕ and the output is a positive weighted sum of the evaluations of ϕ on the query points.Further, the construction is essentially optimal as any such oblivious estimator needs to make at least (1/ε) Ω(k) queries (see Section 7).In comparison, the previous best bound of Dadush and Vempala [DV12] needed (log k) O(k) queries.We also remark that the query points of our algorithm are essentially the same as that of Dadush and Vempala, however our analysis is quite different and leads to better parameters.
As in the analysis of the dimension reduction step, our analysis of the oblivious estimator relies on a comparison inequality-Kantor's lemma-that allows us to "lift" a simple estimator for the univariate case to the multi-dimensional case.
We first construct a symmetric distribution µ on R that has a simple piecewise flat graph and sandwiches the one-dimensional Gaussian distribution in the following sense.Let ν be a "shrinking" of µ defined to be the probability density function (pdf) of (1 − ε)x for x ← µ.Then, for every symmetric interval I ⊆ R, µ(I) ≤ N (I) ≤ ν(I).
Kantor's lemma [Kan77] says that for pdf's µ, ν as above that are in addition unimodal, the above relation carries over to the product distributions µ k , ν k : for every symmetric convex set
K ⊆ R k , µ k (K) ≤ N k (K) ≤ ν k (K)
. This last inequality immediately implies that semi-norms cannot distinguish between µ k and N k : for any semi-norm ϕ,
E µ k [ϕ(x)] = (1 ± ε) E N k [ϕ(x)].
We then suitably prune the distribution µ k to have small support and prove Theorem 4.1.
Our main result, Theorem 1.2, follows by first reducing the dimension as in the previous section and applying Theorem 4.1 to the semi-norm ϕ :
R k → R + , ϕ(x) = sup i | u i , x | for the projected vectors {u 1 , . . . , u m }.
Dimension Reduction
The use of JLL type random projections for estimating the supremum comes from the following comparison inequality for Gaussian processes.We call a collection of real-valued random variables {X t } t∈T a Gaussian process if every finite linear combination of the variables has a normal distribution with mean zero.For a reference to Slepian's lemma we refer the reader to Corollary 3.14 and the following discussion in [LT91].
Theorem 3.1 (Slepian's Lemma [Sle62]).Let {X t } t∈T and {Y t } t∈T be two Gaussian processes such that for every s
, t ∈ T , E[(X s − X t ) 2 ] ≤ E[(Y s − Y t ) 2 ]. Then, E[sup t X t ] ≤ E[sup t Y t ].
We also need a derandomized version of the Johnson-Lindenstrauss Lemma.
Theorem 3.2 ([EIO02]
).For every ε > 0, there exists a deterministic (dm 2 (log m + 1/ε) O(1) )time algorithm that given vectors v 1 , . . ., v m ∈ R d computes a linear mapping A :
R d → R k for k = O((log m)/ε 2 ) such that for every i, j ∈ [m], v i − v j 2 ≤ A(v i ) − A(v j ) 2 ≤ (1 + ε) v i − v j 2 .
Combining the above two theorems immediately implies the following.Lemma 3.3.For every ε > 0, there exists a deterministic (dm 2 (log m + 1/ε) O(1) )-time algorithm that given vectors v 1 , . . ., v m ∈ R d computes a linear mapping A :
R d → R k for k = O((log m)/ε 2 ) such that E x←N d [sup i | v i , x |] ≤ E y←N k [sup i | A(v i ), y |] ≤ (1 + ε) E x←N d [sup i | v i , x |]. (3.1) Proof. Let V = {v 1 , . . . , v m } ∪ {−v 1 , .
. ., −v m } and let {X v } v∈V be the Gaussian process where the joint distribution is given by
X v ≡ v, x for x ← N d . Then, E x←N d [sup i | v i , x |] = E[sup v X v ].
Let A : R d → R k be the linear mapping as given by Theorem 3.2 applied to V .Let {Y v } v∈V be the "projected" Gaussian process with joint distribution given by Y
v ≡ A(v), y for y ← N k . Then, E y←N k [sup i | v i , y |] = E[sup v Y v ].
Finally, observe that for any
u, v ∈ V , E[(X u − X v ) 2 ] = u − v 2 2 ≤ A(u) − A(v) 2 2 = E[(Y u − Y v ) 2 ] ≤ (1 + ε) 2 E[(X u − X v ) 2 ].
Combining the above inequality with Slepian's lemma Lemma 3.1 applied to the pairs of processes
({X v } v∈V , {Y v } v∈V ) and ({Y v } v∈V , {(1 + ε)X v } v∈V ) it follows that E[sup v X v ] ≤ E[sup v Y v ] ≤ E[sup v (1 + ε)X v ] = (1 + ε) E[sup v X v ].
The lemma now follows.
Oblivious Estimators for Semi-Norms in Gaussian Space
In the previous section we reduced the problem of computing the supremum of a d-dimensional Gaussian process to that of a Gaussian process in k = O((log m)/ε 2 )-dimensions.Thus, it suffices to have an algorithm for approximating the supremum of Gaussian processes in time exponential in the dimension.We will give such an algorithm that works more generally for all semi-norms.
Let ϕ : R k → R + be a semi-norm.That is, ϕ satisfies the triangle inequality and is homogeneous.For normalization purposes we assume that 1 ≤ E N k [ϕ(X)] and the Lipschitz constant of ϕ is at most k O(1) .Theorem 4.1.For every ε > 0, there exists a set S ⊆ R k with |S| = (1/ε) O(k) and a function p : R k → R + computable in poly(k, 1/ε) time such that the following holds.For every semi-norm ϕ : R k → R + ,
(1 − ε) x∈S p(x)ϕ(x) ≤ E X←N k [ϕ(X)] ≤ (1 + ε) x∈S p(x)ϕ(x) .
Moreover, successive elements of S can be enumerated in poly(k, 1/ε) time and O(k log(1/ε)) space.
Theorem 2.1 follows immediately from the above.
Proof of Theorem 2.1.Follows by enumerating over the set S and computing x∈S p(x)ϕ(x) by querying ϕ on the points in S.
We now prove Theorem 4.1.Here and henceforth, let γ denote the pdf of the standard univariate Gaussian distribution.Fix ε > 0 and let δ > 0 be a parameter to be chosen later.Let µ ≡ µ ε,δ be the pdf which is a piecewise-flat approximator to γ obtained by spreading the mass γ gives to an interval I = [iδ, (i + 1)δ) evenly over I. Formally, µ(z) = µ(−z) and for z > 0, z ∈ [iδ, (i + 1)δ),
µ(z) = γ([iδ, (i + 1)δ)) δ . (4.1)
Clearly, µ defines a symmetric distribution on R. We will show that for δ ≪ ε sufficiently small, semi-norms cannot distinguish the product distribution µ k from N k : Lemma 4.2.Let δ = (2ε) 3/2 .Then, for every semi-norm ϕ : R k → R,
(1 − ε) E X←µ k [ϕ(X)] ≤ E Z←N k [ϕ(Z)] ≤ E X←µ k [ϕ(X)].
We first prove Theorem 4.1 assuming the above lemma, whose proof is deferred to the next section.
Proof of Theorem 4.1.Let μ be the symmetric distribution supported on δ(Z + 1/2) with pdf defined by μ(δ
(i + 1/2)) = µ([iδ, (i + 1)δ)), for i ≥ 0. Further, let X ← µ k , X ← μk , Z ← N k . We claim that E[ϕ( X)] = (1 ± ε) E[ϕ(Z)].
Let Y be uniformly distributed on [−δ, δ] k and observe that random variable X ≡ X + Y in law.Therefore,
E[ϕ(X)] = E[ϕ( X + Y )] = E[ϕ( X)] ± E[ϕ(Y )] = E[ϕ( X)] ± δ E[ϕ(Y /δ)] = E[ϕ( X)] ± δ E Z ′ ∈u[−1,1] k [ϕ(Z ′ )] = E[ϕ( X)] ± δ E[ϕ(Z)] (Lemma 5.7). (4.2) Thus, by Lemma 4.2, E[ϕ( X)] = (1 ± O(ε)) E[ϕ(Z)](4.3)
We next prune μk to reduce its support.Define p : R k → R + by p(x) = μk (x).Clearly, p(x) being a product distribution is computable in poly(k, 1/ε) time.
Let S = (δ(Z + 1/2)) k ∩ B 2 (3 √ k)
, where B 2 (r) ⊆ R k denotes the Euclidean ball of radius r.As ϕ has Lipschitz constant bounded by k O(1) , a simple calculation shows that throwing away all points in the support of X outside S does not change E[ϕ( X)] much.It is easy to check that for x / ∈ S, p(x) ≤ exp(− x 2 2 /4)/(2π) k/2 .Therefore,
E[ϕ( X)] = x p(x)ϕ(x) = x∈S p(x)ϕ(x) + x / ∈S p(x)ϕ(x) = x∈S p(x)ϕ(x) ± x / ∈S exp(− x 2 2 /4) (2π) k/2 • (k O(1) x 2 ) = x∈S p(x)ϕ(x) ± o(1). (4.4)
From Equation 4.3 and the above equation we get (recall that E[ϕ(Z)] ≥ 1)
E[ϕ(Z)] = (1 ± O(ε)) x∈S p(x)ϕ(x) ,
which is what we want to show.
We now reason about the complexity of S. First, by a simple covering argument |S| < (1/δ) O(k) :
|S| < V ol (B 2 (3 √ k) + [−δ, δ] k ) V ol ([−δ, δ] k ) = (1/δ) O(k) = (1/ε) O(k) ,
where for sets A, B ⊆ R k , A+B denotes the Minkowski sum and V ol denotes Lebesgue volume.This size bound almost suffices to prove Theorem 4.1 except for the complexity of enumerating elements from S. Without loss of generality assume that R = 3 √ n/δ is an integer.Then, enumerating elements in S is equivalent to enumerating integer points in the n-dimensional ball of radius R.This can be accomplished by going through the set of lattice points in the natural lexicographic order, and takes poly(k, 1/ε) time and O(k log(1/ε)) space per point in S.
5 Proof of Lemma 4.2
Our starting point is the following definition that helps us compare multivariate distributions when we are only interested in volumes of convex sets.We shall follow the notation of [Bal03].
Definition 5.1.Given two symmetric pdf 's, f, g on R k , we say that f is less peaked than g (f g)
if for every symmetric convex set K ⊆ R k , f (K) ≤ g(K).
We also need the following elementary facts.The first follows from the unimodality of the Gaussian density and the second from partial integration.Fact 5.2.For any δ > 0 and µ as defined by Equation 4.1, µ is less peaked than γ.
Fact 5.3.Let f, g be distributions on R k with f g.Then for any semi-norm ϕ :
R k → R, E f [ϕ(x)] ≥ E g [ϕ(x)].
Proof.Observe that for any t > 0, {x :
ϕ(x) ≤ t} is convex. Let random variables X ← f , Y ← g. Then, by partial integration, E[ϕ(X)] = ∞ 0 ϕ ′ (t) Pr[ϕ(X) > t]dt ≥ ∞ 0 ϕ ′ (t) Pr[ϕ(Y ) > t]dt = E[ϕ(Y )].
The above statements give us a way to compare the expectations of µ and γ for one-dimensional convex functions.We would now like to do a similar comparison for the product distributions µ k and γ k .For this we use Kanter's lemma [Kan77], which says that the relation is preserved under tensoring if the individual distributions have the additional property of being unimodal.Definition 5.4.A distribution f on R n is unimodal if f can be written as an increasing limit of a sequence of distributions each of which is a finite positively weighted sum of uniform distributions on symmetric convex sets.
Theorem 5.5 (Kanter's Lemma [Kan77]; cf.[Bal03]).Let µ 1 , µ 2 be symmetric distributions on R n with µ 1 µ 2 and let ν be a unimodal distribution on R m .Then, the product distributions
µ 1 × ν, µ 2 × ν on R n × R m satisfy µ 1 × ν µ 2 × ν.
We next show that µ "sandwiches" γ in the following sense.
Lemma 5.6.Let ν be the pdf of the random variable y = (1−ε)x for x ← µ.Then, for δ ≤ (2ε) 3/2 , µ γ ν.
Proof.As mentioned above, µ γ.We next show that γ ν.Intuitively, ν is obtained by spreading the mass that γ puts on an interval I = [iδ, (i + 1)δ) evenly on the smaller interval (1 − ε)I.The net effect of this operation is to push the pdf of µ closer towards the origin and for δ sufficiently small the inward push from this "shrinking" wins over the outward push from going to µ.
Fix an interval
I = [−iδ(1 − ε) − θ, iδ(1 − ε) + θ] for 0 ≤ θ < δ(1 − ε). Then, ν(I) = ν ( [−iδ(1 − ε), iδ(1 − ε)] ) + 2 ν ( [iδ(1 − ε), iδ(1 − ε) + θ] ) (5.1) = γ ( [−iδ, iδ] ) + 2 θ • γ( [iδ, (i + 1)δ) ) δ(1 − ε) .
(5.2)
We now consider two cases.Case 1: i ≥ (1 − ε)/ε so that iδ(1 − ε) + θ ≤ iδ.Then, from the above equation,
ν(I) ≥ γ ( [−iδ, iδ] ) ≥ γ ( [−iδ(1 − ε) − θ, iδ(1 − ε) + θ] ) = γ(I). Case 2: i < (1 − ε)/ε. Let α = (i + 1)δ = δ/ε. Then, as 1 − x 2 /2 ≤ e −x 2 /2 ≤ 1, γ((iδ, iδ + θ]) ≤ θ • γ(0), γ( [iδ, (i + 1)δ) ) ≥ δ • γ(0) • (1 − α 2 /2).
Therefore,
ν(I) = γ(I) − 2γ ( (iδ, iδ(1 − ε) + θ] ) + 2θ • γ( [iδ, (i + 1)δ) ) δ(1 − ε) ≥ γ(I) − 2γ ( (iδ, iδ + θ] ) + 2θ • γ( [iδ, (i + 1)δ) ) δ(1 − ε) ≥ γ(I) − 2θγ(0) + 2θ • δ • γ(0) • (1 − α 2 /2) δ(1 − ε) = γ(I) + 2θγ(0) 1 − ε • (ε − α 2 /2) ≥ γ(I),
for α 2 ≤ 2ε, i.e., if δ ≤ (2ε) 3/2 .Lemma 4.2 follows easily from the above two claims.
Proof of Lemma 4.2.Clearly, µ, ν, γ are unimodal and product of unimodal distributions is unimodal.Thus, from the above lemma and iteratively applying Kanter's lemma we get µ k γ k ν k .Therefore, by Fact 5.3, for any semi-norm ϕ,
E µ k [ϕ(X)] ≥ E γ k [ϕ(Y )] ≥ E ν k [ϕ(X)] = E µ k [ϕ((1 − ε)X)] = (1 − ε) E µ k [ϕ(X)].
We now prove the auxiliary lemma we used in proof of Theorem 4.1.
Lemma 5.7.Let ρ be the uniform distribution on [−1, 1].Then, γ ρ and for any semi-norm
ϕ : R k → R, E ρ k [ϕ(x)] ≤ E γ k [ϕ(x)].
Proof.It is easy to check that γ ρ.Then, by Kanter's lemma γ k ρ k and the inequality follows from Fact 5.3.
A PTAS for Supremum of Gaussian Processes
Our main theorem, Theorem 1.2, follows immediately from Lemma 3.3 and Theorem 2.1 applied to the semi-norm ϕ : R k → R defined by ϕ(x) = sup i≤m | A(v i ), x |.
Lowerbound for Oblivious Estimators
We now show that Theorem 4.1 is optimal: any oblivious linear estimator for semi-norms as in the theorem must make at least (C/ε) k queries for some constant C > 0.
Let S ⊆ R k be the set of query points of an oblivious estimator.That is, there exists a function f : R S + → R + such that for any semi-norm ϕ : R k → R + , f ((ϕ(x) : )].We will assume that f is monotone in the following sense: f (x 1 , . . ., x |S| ) ≤ f (y 1 , . . ., y |S| ) if 0 ≤ x i ≤ y i for all i.This is clearly true for any linear estimator (and also for the median estimator).Without loss of generality suppose that ε < 1/4.
x ∈ S)) = (1 ± ε) E Y ←N k [ϕ(Y
The idea is to define a suitable semi-norm based on S: define ϕ : R k → R by ϕ(x) = sup u∈S | u/ u 2 , x |.It is easy to check that for any v ∈ S, v 2 ≤ ϕ(v).Therefore, the output of the oblivious estimator when querying the Euclidean norm is at most the output of the estimator when querying ϕ.In particular,
(1 − ε) E Y ←N k [ Y 2 ] ≤ f (( x 2 : x ∈ S)) ≤ f ((ϕ(x) : x ∈ S)) ≤ (1 + ε) E Y ←N k
that the above is possible only if |S| > (C/ε) k .Let S k−1 denote the unit sphere in R k .For the remaining argument, we shall view Y ← N k to be drawn as Y = RX, where X ∈ S k−1 is uniformly random on the sphere and R ∈ R is independent of X and has a Chi-squared distribution with k degrees of freedom.Let S(ε) = ∪ u∈S {y ∈ S k−1 : | u/ u 2 , y | ≥ 1 − 4ε}.Now, by a standard volume argument, for anyy ∈ S k−1 , Pr X [| X, y | ≥ 1 − 4ε] < (O(ε)) k .Thus, by a union bound, p = Pr X [X ∈ S(ε)] < |S| • (O(ε)) k .Further, for any y ∈ S k−1 \ S(ε), ϕ(y) < 1 − 4ε.Therefore, E X [ϕ(X)] = Pr[X / ∈ S(ε)] • E[ϕ(X)|X / ∈ S(ε)] + Pr[X ∈ S(ε)] • E[ϕ(X)|X ∈ S(ε)] ≤ (1 − p)(1 − 4ε) + p.Thus,E[ϕ(Y )] = E[ϕ(RX)] = E[R] • E[ϕ(X)] ≤ E[ Y 2 ] • ((1 − p)(1 − 4ε) + p).(7.2)Combining Equations 7.1 and 7.2, we get1 − ε ≤ (1 + ε) • ((1 − p)(1 − 4ε) + p) < 1 − 3ε + 2p.As p < |S| • (O(ε)) k , the above leads to a contradiction unless |S| > (C/ε) k for some constant C > 0.
Throughout, N denotes the univariate Gaussian distribution with mean 0 and variance 1 and for a distribution D, X ← D denotes a random variable with distribution D. By a α-factor approximation to a quantity X we mean a number p such that p ≤ X ≤ αp.
This follows from standard concentration bounds for supremum of Gaussian processes; we do not elaborate on it here as we ignore this issue.
The hitting time τ hit (G) is defined as the maximum over all pairs of vertices u, v ∈ G of the expected time for a random walk starting at u to reach v. See the discussion in[Din11] for why this is a reasonable condition.
Reversible markov chains and random walks on graphs. D Aldous, J Fill, preparation.
Convex geometry and functional analysis, Handbook of the Geometry of Banach Spaces. Keith Ball, 2003Elsevier1
Jian Ding, Asymptotics of cover times via gaussian free fields: bounded-degree graphs and general trees. 2011Preprint
Jian Ding, James R Lee, Yuval Peres, Cover times, blanket times, and majorizing measures, STOC. 2011
Deterministic construction of an approximate mellipsoid and its applications to derandomizing lattice algorithms. Daniel Dadush, Santosh Vempala, SODA. 2012
Derandomized dimensionality reduction with applications, SODA. Lars Engebretsen, Piotr Indyk, Ryan O' Donnell, 2002
Deterministic approximation for the cover time of trees. U Feige, O Zeitouni, 2009Preprint, available at
Unimodality and dominance for symmetric random vectors. Marek Kanter, Transactions of the American Mathematical Society. 2291977
Jeff Kahn, Jeong Han Kim, László Lovász, Van H Vu, The cover time, the blanket time, and the matthews bound, FOCS, 2000.
James Lee, Open question: Cover times and the gaussian free field, 2010, Post in Blog tcsmath -"Open Question: Cover Times and the Gaussian Free Field. Dec 9, 2010
Random walks on graphs: A survey. László Lovász, Combinatorics Paul Erdos is Eighty. 211993
Probability in banach spaces: Isoperimetry and processes. Michel Ledoux, Michel Talagrand, 1991SpringerBerlin
The volume of convex bodies and banach space geometry, Cambridge tracts in mathematics. G Pisier, 1999Cambridge University Press
The one-sided barrier problem for gaussian noise. Slepian, Bell System Technical Journal. 1962
The generic chaining: upper and lower bounds of stochastic processes. M Talagrand, 2005Springer
Multiple cover time. Peter Winkler, David Zuckerman, Random Struct. Algorithms. 941996
| [
-0.22422996163368225,
-0.08329196274280548,
0.05797996371984482,
0.008091631345450878,
0.2300991714000702,
0.03047778084874153,
0.25696444511413574,
-0.029564008116722107,
-0.0003716549836099148,
0.0638219490647316,
-0.06935685873031616,
0.1356375813484192,
0.06944458931684494,
0.063757047... |
Petri Net Classes for Collaboration Mining: Assessment and Design Guidelines
12 Sep 2023
Janik-Vasily Benzin janik.benzin@tum.de
Technical University of Munich
TUM School of Computation, Information and Technology
GarchingGermany
Stefanie Rinderle-Ma stefanie.rinderle-ma@tum.de
Technical University of Munich
TUM School of Computation, Information and Technology
GarchingGermany
Petri Net Classes for Collaboration Mining: Assessment and Design Guidelines
12 Sep 2023F79B394D5999A654798EAEA80DC22C93arXiv:2309.06200v1[cs.FL]Collaboration MiningCollaboration Process ModelsPetri Net ClassesDesign Guidelines
Collaboration mining develops discovery, conformance checking, and enhancement techniques for collaboration processes.The collaboration process model is key to represent the discovery result.As for process mining in general, Petri Net classes are candidates for collaboration process models due to their analytical power.However, a standard model class to represent collaboration processes is lacking due to the heterogeneity of collaboration and, thus, of collaboration mining techniques.Collaboration heterogeneity requires to cover, for example, intra-organizational collaborations as well as choreographies that span a process across multiple organizations.A standard collaboration model class would advance collaboration mining by focusing discovery through a common target model, supporting comparison, and enabling flexible mining pipelines.To find a standard model class, we aim at capturing collaboration heterogeneity in a meta model, assess Petri net classes as candidates for collaboration process models through the meta model, and derive design guidelines for the collaboration discovery.
Introduction
Process mining research develops process discovery, conformance checking and enhancement techniques for process orchestrations that define what work is done in what order for similar cases [2,27,4].In contrast, collaboration mining research develops the same for collaboration processes that define what work is done in what order for collaborating cases, i.e., collaboration processes correspond to multiple process orchestrations that collaborate via departments [33], services [24,46], agents [48,49,38], and organizations [55,54,29,15].
For mining process orchestrations the de-facto standard model class is workflow nets [3] to represent what work has to be done in what order as, for example, the workflow net concept underlies many models targeted by process discovery techniques [10].Although declarative process models were also proposed, they are by far in the minority [10] and no discovery technique for collaboration processes targeting a declarative model is known to us.Hence, we focus on procedural models in the following.Nevertheless, a de-facto standard model class for collaboration processes is missing, as the model classes targeted by discovery techniques are diverse, e.g., communication nets [46] vs. composed RM WF nets [33].The heterogeneity of model classes is a consequence of the heterogeneity of collaborations, e.g., message exchanges [15] and handover-of-work [49], from various perspectives, e.g., operational [46] vs. organizational [49], and on various granularity levels, e.g., intra-organizational [33] vs. inter-organizational [15].
The goal of this work is to identify potential standard model classes for collaboration processes as "the choice of target model is very important for the discovery process itself" [1].For this, we analyse the collaboration mining literature and related research areas with respect to the collaboration studied and integrate it in a collaboration process meta model in Sect. 2. Next, we derive assessment criteria from the collaboration process meta model to assess standard Petri net classes with respect to required properties of a standard model class for collaboration processes and findings from the assessment in Sect.3. We focus on Petri net classes due to their expressiveness, graphical and integrating 1 nature, formal semantics, analysis techniques, and tool support [39,3,41].Similar to process mining, collaboration mining starts with discovering a collaboration process model [4] such that the targeted model class determines applicable conformance checking and enhancement techniques.Thus, we translate the assessment findings into design guidelines for process discovery in Sect. 4 and conclude in Sect. 5.
A Collaboration Process Meta Model
The assessment of Petri net classes as standard candidates for collaboration process models in Sect. 3 necessitates an analysis of the heterogeneous collaboration studied in collaboration mining (cf.Sect.1), as the collaboration determines what must be modelled in a collaboration process model.Due to the heterogeneity in what is considered as a collaboration process (CP), we take an integrating approach to understand what has to be modelled in a collaboration process (CP) model by presenting a collaboration process (CP) meta model.
The meta model integrates specifications of what has to be modelled from research areas that study CP models through a top-down approach that starts from scratch and models the CP as it should be executed.In that sense, collaboration mining represents the opposite bottom-up approach by assuming the CP has already been running for some time such that event logs can be extracted from information systems supporting the CP.Hence, the CP meta model brings process models from both top-down and bottom-up approaches together and is presented in Sect.2.1 and instantiated for a real-world CP in Sect.2.2.
Elements of the Collaboration Process Meta Model
To guide the integration of existing CP models, the functional, behavioral, informational, operational and organizational process perspectives [27] are depicted 1 Many alternative modelling languages can be transformed into Petri nets [41].
in Fig. 1.Aside from the analysis question defining the perspective on a process, the resulting main concept, the concept's abstraction relation instances/concept granularities, and elements of the perspective are presented.Existing work taking the top-down or bottom-up approach identifies a perspective's element as the answer to what is collaborating, i.e., the involved collaboration concepts (perspective's elements denoted in blue in Fig. 1).Fig. 1.Process perspectives [27] and research areas that study collaboration between perspective's elements and their relation to the collaboration process meta model.
Existing research areas taking the top-down approach are interorganizational workflows [2,7,9], process choreographies [16,17,20,37,22,21], virtual enterprises [14,26,25], distributed business processes [13,45], service compositions [43,6,4], multi-agent systems [47,48], and (process) instance-spanning constraints [19,53].In contrast, the bottom-up approach is taken by object-centric process mining [5,11] and collaboration mining [24,55,46,54,15,29,38,33,49].Considering both approaches, collaboration can be the result of multiple organizations (denoted in blue as an element of the organizational perspective in Fig. 1) or an organization's departments (non-agents in Fig. 1) collaborating towards achieving a common business goal.Also, collaboration can be the result of multiple services (element of the operational perspective) or agents (organizational perspective) collaborating to execute a CP.Similarly, collaboration can be the result of multiple objects (informational perspective) collaborating to be processed in a CP.Lastly, collaboration can be the result of multiple process instances (behavioral perspective) collaborating to meet the requirements stated in compliance constraints.
Hence, the main element of the CP meta model defining the various collaboration concepts can be an organization, (non-)agent, services, objects, and process instances.To cover the diverse nature of concepts, we conceptualize all these perspective's elements with their respective process orchestration, e.g., the process orchestration of a particular medical department [33] or of a particu-lar web service [46] (cf."conceptualized as" relation in dotted blue in Fig. 1).Our process orchestration conceptualization in the CP meta model is in line with top-down and bottom-up approaches, as work for both approaches typically models its collaboration concept by some process orchestration, e.g., the underlying workflow net for each medical department [33] or for each web service [46].Hence, the meta collaboration process that abstracts the Petri net classes modelling the CP in Fig. 1 consists of process orchestrations that interact in various collaborations, i.e., the process orchestrations of a CP collaborate.
Despite the diverse range of represented concepts in terms of process perspective and granularity level, the relationships between process orchestrations in the CP meta model (cf.Fig. 1) are either a collaboration, e.g., two agent's exchange messages, or inheritance [12], e.g., a service and its subservice are abstracted into a single service.The inheritance relation between process orchestrations captures the various granularity levels of existing works' collaboration concepts (department vs. organization) in the CP meta model.The collaboration relationship can be generally defined as either asynchronous or synchronous [2] (cf.Fig. 1).Message exchanges, e.g., http-messages in web services [46], handover-of-work between process orchestrations, e.g., agent A executes activity "a" and hands the work over to agent B that executes activity "b" [49], and sharing, e.g., a doctor in a clinic can only do one task at a time [33], are studied for asynchronous collaboration between process orchestrations.On the contrary, synchronous collaboration is studied as an activity that is either executed by multiple process orchestrations together, e.g., an internist and a surgeon consult to determine necessary medication for a patient [33], or multiple process orchestrations are referenced in an activity, e.g., the order and package for packing the items of an order [5].
The applicability of the four collaboration types in the CP meta model to a real-world manufacturing CP are shown in the next section.
Collaboration Process Meta Model Instance in Manufacturing
To show the applicability of the CP meta model, we instantiate it (depicted in Fig. 2) for a real-world manufacturing CP [35].The CP is a batch production of chess pieces orchestrated by the Cloud Process Execution Engine (CPEE) [36].The CPEE executes the batch production process orchestration (denoted in blue in Fig. 2) that refers to the top-level orchestration process executed by the CPEE.The batch production produces all chess pieces that are purchased in an order (informational process orchestration related by synchronous collaboration <sync> in Fig. 2).The batch production process orchestration instantiates a production process orchestration for each produced chess piece by message exchange (<msg> relation between batch production and production) that is then executed in parallel by the CPEE.As soon as the production process orchestration is finished, it sends a confirmation message back to the batch production process orchestration.Cardinality constraints for the various collaboration relations are also depicted.For example, a single batch production produces all orders in the CP synchronously.Fig. 2. Selected process orchestrations of a collaboration process meta model instance of the chess piece batch production recorded in [35] as multiple event logs.
Subprocesses instantiated by a behavioral process orchestration, i.e., process orchestrations instantiated with a blocking semantic [36], are a synchronous collaboration, e.g., production and machining in Fig. 2. The CPEE has a finegrained activity lifecycle model, that is referred to by the activity lifecycle operational process orchestration in Fig. 2. Hence, the respective behavioral and the operational process orchestrations synchronously collaborate by executing the respective activity lifecycle transitions.A MT45 lathe machine, an IRB2600 industrial robot and a Keyence precision measurement machine are responsible for executing the CP.As there is only a single MT45, IRB2600 and Keyence machine, these limited resources are shared by the production process orchestration.The machines are orchestrated by message exchanges, i.e., their process orchestrations collaborate in a <msg> collaboration with the production.
Following the meta model in Fig. 1, the CP meta model instance in Fig. 2 abstracts a concrete Petri net CP model that can be mined for the batch production event logs.Depending on the analysis question motivating the mining of a CP model for the batch production, a subset of process orchestrations can be selected to scope the mined CP model.As it is not clear, what Petri net class should be targeted for the CP model by process discovery (cf.Sect.1), the next section assesses candidate Petri net classes.
Assessment of Petri Net Classes in Modelling Collaboration Processes
As elaborated in Sect.2.1, capturing CP in their entirety is a challenging task, in particular, w.r.t. the CP model class and the CP discovery technique which are tightly intertwined [1].Hence, in this section, we assess existing Petri Net classes for their capability of modelling and discovering CPs.
Assessment Criteria
Given the existing research areas that study CPs in Sect.2, through snowballing and expert knowledge, we identify 20 Petri net classes that are target candidates as CP models for collaboration mining as depicted in Tab. 1.The assessment aims to determine the properties of each Petri net class in modelling CP models.The Petri net classes are presented in reference to their main study and year of publication.To assess the Petri net classes, general properties characterize the class from a general conceptual and theoretical perspective, mining properties characterize the class with respect to collaboration mining, and collaboration properties characterize the class with respect to the four types of collaboration occurring in the CP meta model (cf.Fig. 1).General properties of Petri net classes are the approach [37], Turing completeness [39], ability to represent data (cf.control vs. production data in Sect.2) and the proposed type of semantics [51].To build a CP model, two approaches exist: (T)op-down starts from scratch and models the CP manually by starting with the definition of process orchestrations and collaborations and further refining the workflow nets, while (B)ottom-up starts with an event log recorded from information systems supporting the CP execution and mines a CP model.Next, Petri net classes can either be Turing complete (+) or not (−).If the Turing completeness is only conjected, the conjecture is denoted with a ?, e.g., − ? .
As the ability to represent a concept in a Petri net class can either be −, i.e., the class definition prohibits the representation, (I)mplicit, i.e., the concept can theoretically be represented in the class, but has no dedicated element in the definition, or (E)xplicit, i.e., the concept has a dedicated element in the definition, the properties data, CP representation and all four collaboration properties are based on this distinction.Petri net semantics can either be (I)nterleaving, i.e., semantics is defined as traces of fired transitions such that transition labels always interleave/are totally ordered, and (T)rue concurrency, i.e., semantics is defined as a causal net [51] such that transition firings can be partially ordered or "truly concurrent".
Mining properties are the CP representation, discovery technique (PD), rediscoverability [8], and soundness [2].As CPs are a composition of process orchestrations, e.g.[2,33], CP representation refers to the representation of workflow net compositions.To mine a CP model that is an instance of the Petri net class, a discovery technique targeting that Petri net class has to either exist, is unknown to exist (? ), or is (I)nherited from a Petri net subclass.An important and desired property of a Petri net for collaboration mining is its soundness (and generalized definitions such as identifier soundness [11]) that can either be (N)ot (A)pplicable as the class is too general, unknown (? ) as a restated definition is missing, (U)ndecidable or (D)ecidable as a decision problem, and (S)ound by construction.
Findings
From the assessment result in Tab. 1, we deduce nine findings.The first finding is that research on candidate Petri net classes started with the top-down approach and has gradually put more focus on the bottom-up approach.The second finding is that for 19 Petri net classes, the approach assessment is straightforward, while the typed Jackson net proposal [11] fuses the top-down with the bottom-up approach by taking both approaches in turn and bringing them together through a framework for rediscoverability.However, their motivation puts more focus on the bottom-up approach.The third finding is the observation that Typed Jackson nets and object-centric Petri nets [5] are the only bottom-up approaches with an explicit data representation, a consequence of recent efforts to mine CP models for the informational process perspective (cf.Fig. 1) in which process orchestrations are objects and collaboration is synchronous.Considering the general properties, a fourth finding is that there is no existing discovery technique that defines a true concurrency semantics for its Petri net class.The fourth finding contrasts a recent effort on true concurrency through systems mining by [23] and related efforts on partial order-based process mining [32].
Considering the mining properties assessment in Tab. 1, a fifth finding is that early Petri net classes inherit discovery techniques from later proposals for Petri net subclasses, e.g. the Colliery technique [15] is a discovery technique for the Interaction Petri net class, which is a subclass of the interorganizational workflow proposed nine years earlier.The sixth finding is that discovery techniques were only proposed three times for an existing Petri net class proposed in a top-down approach, i.e., the two approaches are brought together through distinct publications in [24,15] for the interaction Petri net and in [29] for the industry net.We conject that both the interaction Petri net and industry net are equivalent both in terms of the assessement and theoretically, which emphasizes the need for a central Petri net class for collaboration mining to alleviate potential redundancies in research.The seventh finding is that rediscoverability and sound by construction are rare and coincide in typed Jackson nets, while the importance of soundness in mining is confirmed through classes having a discovery technique, soundness is either ?, decidable or sound by construction.
Considering the collaboration properties assessment in Tab. 1, the eighth finding is that colored Petri nets and object systems are the only classes that explicitly represent all four collaboration types, but lack a native discovery technique targeting that class.Although the discovery technique [5] for object-centric Petri nets results in an inherited discovery technique for colored Petri nets, the former class lacks explicit representation of three of the four collaboration types.In contrast, the classes integrated RM WF net and composed RM WF net targeted by the discovery techniques in [55] and [33] explicitly represent three of the four collaboration types.The multi-agent system net targeted by the agent miner [49] is the only class particularly designed for explicitly representing the missing handover collaboration type, pointing to a potential fused class with explicit representation of all four classes and a discovery technique that comes with it.Overall, the eighth finding highlights that the early classes colored Petri net and object systems are too general and powerful to be targeted by a discovery technique (yet), but proposed subclasses for which a discovery technique exists do not yet come with the explicit modelling of all four collaboration types.The ninth and final finding is that there is yet no class for collaboration mining that the workflow net constitutes for process orchestration mining.The next section translates the nine findings into design guidelines for collaboration miners.
Design Guidelines for Process Discovery
The assessment of existing Petri net classes as standard candidates for CPs Sect. 3 resulted in nine findings that are the foundation of the design guidelines for future process discovery in collaboration mining.The search for the standard Petri net class for collaboration mining continues and underlies the first three guidelines:
G1 Take the balance between (explicit) modelling and decision power of your targeted Petri net class actively into account.Existing discovery techniques target either the one end, e.g.[11] with good decision power on soundness and rediscoverability, but lack of three collaboration types, or the other end of the bargain, [33] with good modelling power, but lack of known decision power on soundness and rediscoverability.A future discovery technique targeting a (potentially new) class that has modelling power to represent all four collaboration types and good decision power not only brings together the top-down and bottom-up approach, but also is applicable to the challenges studied in a diverse range of research areas and their respective application domains (cf.Fig. 1).G2 Match your discovery technique's design rationale with the properties of existing classes to access the existing theoretical and practical knowledge and improve rather algorithmically instead of by definition of a new class.If a new class is still necessary, take the first guideline into account.G3 State your targeted class explicitly and formally, as it allows straightforward assessment similar to Sect.3.1 and is part of the first maturity stage [52] of your discovery technique.Have all four maturity stages in mind.G4 Think three times about not taking a divide-and-conquer approach to discovery, as the CP is a composition.If you have another approach, motivate it well.G5 Balance your design guided by the previous four guidelines with your discovery technique's complexity to achieve sufficient efficiency for practical purposes.
By taking these guidelines into account, collaboration mining techniques can be flexibly combined, easily compared and assessed, and come with a wellresearched theoretical foundation.Limitations: Despite the extensive set of covered techniques and research areas, the heterogeneity of collaboration results may result in having missed existing work on collaboration.Also, the set of assessed Petri net classes is likely not completely comprehensive.Hence, a Petri net class might exists already that is the best candidate for a standard CP model.Additionally, the criteria can be further refined to improve the characterization of the standard CP model.
Conclusion
The integration of heterogeneous collaboration in our CP meta model enables the assessment of existing Petri net classes with respect to properties of a standard model class for CP and can guide new collaboration mining techniques beginning with process discovery.As a clear standard Petri net class for CP is still missing, future techniques should take this lack of standardization into account to advance collaboration mining in a coherent way.Additionally, a fusion of the top-down and bottom-up approach opens up yet to be utilized ways of combining results from both sides.
Table 1 .
1
Overview of the 20 Petri net model classes with CP modelling assessment.
General PropertiesMining PropertiesCollaboration PropertiesClassMain StudyYear Appr.Turing Compl.DataSeman-ticsCP Repr.PDRedis-cover.Sound-nessMes-sagesHand-overShar-ingActi-vityPetri Net[40] 1962 T−[39]II/TII−NAIIIIColored Petri Net [28] 1981 T−[28] EIII−NAEEEEObject System[50] 1996 T+[31] EIEI−NAEEEEInterorgan. Workflow[2] 1998 T−[39]IIEI−DEIIEInteraction Petri Net[16] 2007 T−[39]IIE[24] [15]−?E 2II−Compositional Service Tree[6] 2009 T−[39]IIE?−DEII−υ-PN[44] 2011 T−[44] EII?−UIIIIIntegrated RM WF net[55] 2013 B−[39]IIE [55] −DEIEEHealthcare Petri Net[34] 2018 T− ?IIE?−?IEE−Synchronuous Proclet System[18] 2019 T − ? [18] ETE?−NAIIIEt-PNID[41] 2019 T−[39] EIEI−UIIIECommunication Net[46] 2019 B− ?IIE [46] −?EII−Top-Level Process Model[54] 2020 B− ?IIE [54] −DEIIISystem Net[42] 2020 T− ?ETE?−NAEEIIObject-centric Petri Net[5] 2020 B− ?EIE [5]−?IIIEIndustry Net[30] 2022 T− ?IIE [29] −?EII−Multi-Agent System Net[49] 2023 B−[39]IIE [49] −DIEIIGeneralized Workflow Net[38] 2023 B− ?IIE [38] −DEIIEComposed RM WF net[33] 2023 B−[39]IIE [33] −?EIEETyped Jackson Net[11] 2023 B−[11] EIE [11] +SIIIE
Interaction Petri nets are the only model class in our overview, that conceptualizes a message exchange as an atomic, synchronous firing of a transition in a Petri net[16].
On the Representational Bias in Process Mining. W M P Van Der Aalst, IEEE 20th International Workshops on Enabling Technologies: Infrastructure for Collaborative Enterprises. 2011. Jun 2011
Modeling and analyzing interorganizational workflows. W M P Van Der Aalst, Proceedings 1998 International Conference on Application of Concurrency to System Design. 1998 International Conference on Application of Concurrency to System Design1998
Interorganizational workflows: An approach based on message sequence charts and petri nets. W M P Van Der Aalst, Systems Analysis Modelling Simulation. 341999
W M P Van Der Aalst, Service Mining: Using Process Mining to Discover, Check, and Improve Service Behavior. Oct 20136
Discovering object-centric Petri nets. W M P Van Der Aalst, A Berti, Fundamenta informaticae. 1751-42020
Compositional Service Trees. W M P Van Der Aalst, K M Van Hee, P Massuthe, Applications and Theory of Petri Nets. Berlin, HeidelbergSpringer2009
Enacting interorganizational workflows using nets in nets. W M P Van Der Aalst, D Moldt, R Valk, F Wienberg, Proceedings of the 1999 Workflow Management Conference. the 1999 Workflow Management ConferenceCiteseer199970
Workflow mining: discovering process models from event logs. W M P Van Der Aalst, T Weijters, L Maruster, IEEE Trans Knowl Data Eng. 169Sep 2004
The P2P Approach to Interorganizational Workflows. W M P Van Der Aalst, M Weske, Advanced Information Systems Engineering. Berlin, HeidelbergSpringer2001
Automated Discovery of Process Models from Event Logs: Review and Benchmark. A Augusto, R Conforti, M Dumas, Rosa, IEEE Trans Knowl Data Eng. 314Apr 2019
There and Back Again. D Barenholz, M Montali, A Polyvyanyy, Reijers, Application and Theory of Petri Nets and Concurrency. ChamSpringer2023
Inheritance of behavior. T Basten, W Van Der Aalst, The Journal of Logic and Algebraic Programming. 4722001
Event-based failure prediction in distributed business processes. M Borkowski, W Fdhila, M Nardelli, S Rinderle-Ma, S Schulte, Inf. Syst. 812019
Partnership Synthesis for Virtual Enterprises. X N Chu, S K Tso, W J Zhang, Q Li, Int. J. Adv. Manuf. Technol. 195Mar 2002
A Technique for Collaboration Discovery. F Corradini, B Re, L Rossi, F Tiezzi, Enterprise, Business-Process and Information Systems Modeling. ChamSpringer2022
Local Enforceability in Interaction Petri Nets. G Decker, M Weske, BPM 2007. Berlin, HeidelbergSpringer20074714
Interaction-centric modeling of process choreographies. G Decker, M Weske, Information Systems. 362Apr 2011
Describing Behavior of Processes with Many-to-Many Interactions. D Fahland, Application and Theory of Petri Nets and Concurrency. ChamSpringer2019
Classification and Formalization of Instance-Spanning Constraints in Process-Driven Applications. W Fdhila, M Gall, S Rinderle-Ma, Mangler, BPM 2016. Springer20169850
Dealing with change in process choreographies: Design and implementation of propagation algorithms. W Fdhila, C Indiono, S Rinderle-Ma, M Reichert, Information Systems. 49Apr 2015
Verifying compliance in process choreographies: Foundations, algorithms, and implementation. W Fdhila, D Knuplesch, S Rinderle-Ma, M Reichert, Information Systems. 101983Jan 2022
Change and Compliance in Collaborative Processes. W Fdhila, S Rinderle-Ma, D Knuplesch, M Reichert, IEEE International Conference on Services Computing. New York City, NY, USAIEEE2015. Jun 2015
P Fettke, W Reisig, arXiv:2202.01289Systems Mining with Heraklit: The Next Step. Jun 2022
Log-based mining techniques applied to Web service composition reengineering. W Gaaloul, K Baïna, C Godart, Serv. Oriented Comput. Appl. 22Jul 2008
Designing normative open virtual enterprises. E Garcia, A Giret, V Botti, Enterp. Inf. Syst. 103Mar 2016
Dynamic business network process management in instant virtual enterprises. P Grefen, N Mehandjiev, G Kouvas, G Weichhart, R Eshuis, Computers in Industry. 602Feb 2009
Workflow management: modeling concepts, architecture and implementation. S Jablonski, C Bussler, ITP New Media. 1996
Coloured petri nets and the invariant-method. K Jensen, Theor Comput Sci. 1431981
Distributed Synthesis of Asynchronously Communicating Distributed Process Models. P Kwantes, J Kleijn, Transactions on Petri Nets and Other Models of Concurrency XVI. Berlin, HeidelbergSpringer2022
On the synthesis of industry level process models from enterprise level process models. P M Kwantes, J Kleijn, ATAED@ Petri Nets/ACSD. 2018
Properties of Object Petri Nets. M Köhler, H Rölke, Applications and Theory of Petri Nets. Springer2004. 2004
Partial-order-based process mining: a survey and outlook. S J J Leemans, S J Van Zelst, X Lu, Knowledge and Information Systems. Nov 2022
Cross-Department Collaborative Healthcare Process Model Discovery From Event Logs. C Liu, H Li, S Zhang, Cheng, IEEE Trans. Autom. Sci. Eng. 203Jul 2023
Modular Petri net modeling of healthcare systems. C Mahulea, L Mahulea, J M García Soriano, J M Colom, Flex. Serv. Manuf. J. 301Jun 2018
J Mangler, M Ehrendorfer, XES Chess Pieces Production. May 2023
Cloud Process Execution Engine: Architecture and Interfaces. J Mangler, S Rinderle-Ma, arXiv:2208.12214Sep 2022
Automating data exchange in process choreographies. A Meyer, L Pufahl, K Batoulis, D Fahland, M Weske, Information Systems. 53Oct 2015
Discovering architecture-aware and sound process models of multi-agent systems: a compositional approach. R Nesterov, L Bernardinello, I Lomazova, L Pomello, Softw Syst Model. 221Feb 2023
Petri Nets. J L Peterson, ACM Computing Surveys. 93Sep 1977
C A Petri, Kommunikation mit automaten. 1962
Information Systems Modeling: Language, Verification, and Tool Support. A Polyvyanyy, J M E M Van Der Werf, S Overbeek, R Brouwers, Advanced Information Systems Engineering. ChamSpringer2019
Composition of Component Models -A Key to Construct Big Systems. W Reisig, Leveraging Applications of Formal Methods, Verification and Validation: Engineering Principles. ChamSpringer2020
Equivalence of Web Services in Process-Aware Service Compositions. S Rinderle-Ma, M Reichert, M Jurisch, 2009 IEEE International Conference on Web Services. Jul 2009
Decidability and complexity of Petri nets with unordered data. F Rosa-Velardo, D De Frutos-Escrig, Theor Comput Sci. 41234Aug 2011
Towards Process Support for Cloud Manufacturing. S Schulte, P Hoenisch, C Hochreiner, Dustdar, IEEE 18th International Enterprise Distributed Object Computing Conference. Ulm, Germany2014. Sep 2014
A Distributed Discovery of Communicating Resource Systems Models. A Stroiński, D Dwornikowski, J Brzeziński, IEEE Trans. Serv. Comput. 122Mar 2019
A framework for service enterprise workflow simulation with multi-agents cooperation. W Tan, W Xu, F Yang, Xu, Enterp. Inf. Syst. 742013
Agent System Mining: Vision, Benefits, and Challenges. A Tour, A Polyvyanyy, A Kalenkova, IEEE Access. 92021
Agent Miner: An Algorithm for Discovering Agent Systems from Event Data. A Tour, A Polyvyanyy, A Kalenkova, A Senderovich, arXiv:2212.01454Jul 2023
R Valk, On Processes of Object Petri Nets. 1996
Petri net models for algebraic theories of concurrency. R Van Glabbeek, F Vaandrager, PARLE Parallel Architectures and Languages Europe. Springer1987II
All that glitters is not gold: Four maturity stages of process discovery algorithms. J M E M Van Der Werf, A Polyvyanyy, B R Van Wensveen, M Brinkhuis, H A Reijers, Information Systems. 114102155Mar 2023
Defining Instance Spanning Constraint Patterns for Business Processes Based on Proclets. K Winter, S Rinderle-Ma, Conceptual Modeling. ChamSpringer2020
Top-Down Process Mining From Multi-Source Running Logs Based on Refinement of Petri Nets. Q Zeng, H Duan, C Liu, IEEE Access. 82020
Cross-organizational collaborative workflow mining from a multi-source log. Q Zeng, S Sun, H Duan, Liu, Decis Support Syst. 54Feb 2013
| [
-0.09626275300979614,
-0.050932951271533966,
-0.17837223410606384,
-0.11299403011798859,
0.0588991753757,
-0.11477850377559662,
0.019744891673326492,
-0.01893468201160431,
0.062136758118867874,
0.0948185846209526,
-0.19329464435577393,
-0.0321352519094944,
0.08418673276901245,
0.1508683264... |
10.32843/2663-
У статті авторами розглядаються психологічні особливості прояву тривожності у підлітковому віці. За результатами досліджень було виявлено домінування високого та підвищеного рівня тривожності підлітків. Тривожність становить собою фактор, який визначає поведінку людини в конкретних ситуаціях та загалом. Встановлено, що підліткова тривожність часто маскується під поведінкові прояви інших проблем, таких як агресивність, залежність і схильність до підпорядкування, облудність, лінощі як результат «вивченої безпорадності», помилкова гіперактивність, відхід у хворобу та інше. Порівнюючи результати за класами, виявлено, що досліджувані під час перебування в одному навчальному закладі, але у різних колективах однолітків, схильні переживати тривожність різного рівня інтенсивності. Реактивна та особистісна тривожність проявляється, коли підліток потрапляє в неприємну для нього ситуацію. Негативні психологічні стани, тривожність накопичується у підлітка ще задовго до появи неприємної ситуації і досягає свого максимуму особистісна тривожність у момент, наприклад, коли учень отримає відповідальне (значиме) завдання. Реактивна тривожність іноді, залежно від своєї масштабності, може перерости в невроз. В більшості учнів переважатиме особистісна тривожність над реактивною. Результати попередніх досліджень свідчать про наявність у досліджуваній вибірці респондентів з високим рівнем тривожності та фрустрованості, небажанням зближатись на емоційній основі. Також зафіксовано наявність таких бар'єрів, як сором'язливість та боязливість, яким притаманний як позитивний, так і негативний прояв. Встановлено необхідність підтримувати принцип «золотої середини», адже нахабство, самовпевненість, егоїзм не є помічниками і зазвичай лише ускладнюють відносини та спілкування. Результати нашого дослідження свідчать про те, що в підлітковому віці тривожність залишається гострою проблемою. Тому перспективою подальших досліджень буде розроблення психокорекційної програми зняття тривожності підлітків. Отримані результати можуть бути використані як під час навчання майбутніх психологів, роз-робки психокорекційної програми, так і під час сімейного консультування. Ключові слова : особистість, ситуативна тривожність, реактивна тривожність, фрустрованість, агресивність, ригідність, сором'язливість та боязливість. The authors discuss the psychological features of anxiety in adolescence. The results of the study revealed a predominance of high and high levels of anxiety in adolescents. Anxiety is a factor that determines a person's behavior in specific situations and in general. It is established that adolescent anxiety is often masked by the behavioral manifestations of other problems, such as aggression, dependence and a tendency to subjugate, fornication, laziness as a result of "learned helplessness", false hyperactivity, withdrawal into illness, and more. Comparing the results by class, it is found that they are studied during their stay in one school, but in different peer groups tend to experience anxiety at different levels of intensity. Reactive and personal anxiety is manifested when a teenager gets into an unpleasant situation. Negative psychological states, anxiety accumulates in the teenager long before the unpleasant situation occurs and reaches its maximum personal anxiety at the moment, when the student receives a responsible (meaningful) task. Reactive anxiety can sometimes develop into a neurosis, depending on its magnitude. Most students will be dominated by personal anxiety over reactive ones. The results of previous studies indicate that there is a high level of anxiety and frustration in the sample of respondents that they do not want to approach emotionally. There are also barriers such as shyness and cowardice, which are both positive and negative. There is a need to uphold the principle of the "golden mean", because arrogance, self-confidence, selfishness are not helpers and, as a rule, only complicate relations and communication. However, the results of our study show that anxiety remains an acute problem in adolescence. Therefore, the prospect of further research will be the development of a psycho-correctional program to relieve anxiety in adolescents. The results can be used both in the training of future psychologists, the development of a psycho-corrective program and during family counseling. Key words: personality, situational anxiety, reactive anxiety, frustration, aggressiveness, rigidity, shyness and timidity.
ПСИХОЛОГІЧНІ ОСОБЛИВОСТІ ПРОЯВУ ТРИВОЖНОСТІ У ПІДЛІТКОВОМУ ВІЦІ
PSYCHOLOGICAL PECULIARITIES OF EXPRESSION OF ANXIETY IN ADOLESCENT AGE
Постановка проблеми. У сучасному суспільстві відбуваються складні соціально-економічні зміни. Невизначеність та непередбачуваність майбутнього викликає у більшості людей стан емоційної напруженості. Значна кількість молоді почувають себе самотніми, відчувають душевний дискомфорт внаслідок відсутності довірливих взаємин з однолітками та дорослими, невизначеності соціальної позиції у колективі, несформованості ціннісних орієнтацій, планів на майбутнє [2]. Підлітковий вік є перехідним періодом від дитинства до зрілості. Зміни, що відбуваються в інтелектуальній та емоційній сферах особистості підлітка, породжують новий рівень його самосвідомості, потребу у самоствердженні, у рівноправному і довірливому спілкуванні з ровесниками і дорослими. Тривожність підлітка часто порушує його нормальне життя, нерідко виступає причиною порушення соціальних зв'язків з навколишніми. Одними із частих проявів тривожності в підлітків є апатія, в'ялість, безініціативність. Саме внутрішній конфлікт, суперечливість прагнень дитини, коли одне її сильне бажання суперечить іншому, одна потреба заважає іншій, є причиною виникнення тривоги. «Але щоб сформувалася тривожність як риса особистості, підліток повинен накопичити багаж неуспішних, неадекватних способів подолання стану тривоги» [1].
Аналіз останніх досліджень і публікацій. У зарубіжній психології, на думку більшості дослідників, основними характерними проявами тривожності є: негативний емоційний відтінок, невизначеність предмета переживання, відчуття реальної погрози. Деякі науковці наголошують на такій важливій ознаці тривожності, як спрямованість у майбутнє (У. Макдаугал, С. Мадді, П. Тилліх, Ч. Рікрофт). Вченими виокремлено джерела тривожності:
значуща людина (Г. Салліван, К. Хорні), вну- трішньоособистісні (Д. МакКлеланд, Р. Мей, К. Роджерс, Е. Фром, К. Юнг), перинатальні (С. Гроф, О. Ранк) [3]
. Зазначається, що тривожність є досить суб'єктивним феноменом, який має індивідуально значущі, інтроспективні, поведінкові та фізіологічні прояви.
Сучасні емпіричні дослідження щодо вивчення психологічних детермінант, проявів тривоги, тривожності та страхів стосуються переважно дошкільного, молодшого шкільного, підліткового віку (Є. Калюжна, Н. Карпенко, Т. Ольховецька, Я. Омельченко, О. Скляренко, С. Ставицька, Н. Шевченко) (Шевченко, 2007). Деякі дослідники (І. Кон, Л. Костіна, О. Мікляєва, Г. Прихожан) дотримуються думки про те, що тривожність як стійка особистісна риса формується тільки в підлітковому віці. Підлітковий вік характеризується нерівномірністю та суперечливістю розвитку як на міжіндивідному, так і на внутрішньоіндивідному рівні особистості (Д. Бокум, Г. Крайг, Л. Мудрик, Х. Ремшмідт, І. Шаповаленко).
Попри значні термінологічні розходження та підходи у визначенні видів тривожності (адекватна і неадекватна тривожність (Л. Божович); відкрита і прихована, стійка, генералізована (Г. Прихожан); шкільна, міжособистісна, самооцінна (А. Мікляєва, А. Парафіян, Г. Прихожан, С. Ставицька); зовнішня та внутрішня (І. Мусіна); загальна та специфічна особистісна тривожність (Ю. Ханін); немотивована тривожність (Г. Генінг)), вчені сходяться на думці, що тривога є невіддільним складником існування людини, а її над-мірні прояви призводять до особистісних дисгармоній, внутрішніх протиріч в образі «Я», супроводжуються емоційним дискомфортом, передчуттям небезпеки [4].
Постановка завдання. Метою статті є висвітлення результатів дослідження психологічних особливостей прояву тривожності у підлітковому віці.
Виклад основного матеріалу дослідження. Підлітковий вік характеризується передусім сильним прагненням до особистісної експансії, до самовираження. В цьому віці вперше вибудовується життєва стратегія, що базується на рефлексії і співвідношенні своїх індивідуальних здібностей, статусних, вікових та індивідуальних особливостей і домагань з вимогами суспільства.
У цей період розвитку визначається відповідність власної особистості, характеру, індивідуальності з обраним способом самореалізації в суспільстві, серед інших людей. Вік дає для цього знання і розуміння самого себе, що ведуть до усвідомлення того, що мистецтво життя полягає не тільки в тому, щоб рахуватися і реалізовувати свою індивідуальність, але і в тому, щоб індивідуальні можливості і досягнення ставали основою нового розвитку, відкриття в собі нових здібностей і якостей [2]. Тривога в цьому разі виступає як механізм попередження про необхідність приготуватись до чогось важливого і швидко відновити адаптаційний механізм людської особистості. Коли ж тривога переростає у тривожність і викликає надмірне хвилювання, страх, паніку, агресію чи депресію, вона починає перешкоджати процесу спілкування і стає загрозою для здоров'я.
Основне завдання експерименту полягало у виявленні психологічних особливостей стану тривожності у підлітків. У дослідженні взяли участь 60 школярів 8-9 класу (13-15 років) м. Вінниці. Для вивчення психологічних особливостей прояву тривожності підлітка було використано комплекс методик: методика «Оцінка рівня шкільної тривожності» Б. Філліпса, методика на визначення рівня тривожності Ч. Спілбергера, Ю. Ханіна, методика визначення самооцінки психічних станів Г. Айзенка, діагностика боязкості та сором'язливості Є. Ільїна.
Емпіричне вивчення особливостей зазначеної готовності полягало не тільки в організації дослідження, виборі методів, адекватних меті, але й у виявленні логічного зв'язку між фактами, в узагальненні результатів окремих дослідів, у виведенні певних залежностей та властивостей.
Результати емпіричного дослідження за методикою «Оцінка рівня шкільної тривожності» Б. Філліпса: вивчення рівня і характеру тривожності, пов'язаної зі шкільним життям підлітка, представлені на рис. 1.
ПСИХОЛОГІЯ ОСОБИСТОСТІ
Перший фактор, який досліджено, «загальна тривожність у школі». Цей фактор показує загальний емоційний стан дитини, пов'язаний з різними формами його включення в життя школи. Отримані результати розподілилися таким чином: низька тривожність -0% у 8 класі та 6,4% у 9 класі, знижена тривожність -17,2% (8 клас) та 9,7% у 9 класі, підвищена тривожність -31,4% у 8 класі та 32,3% у 9 класі, висока тривожність -51,7% у 8 класі та 51,6% у 9 класі.
Другий фактор -«переживання соціального стресу» -демонструє емоційний стан дитини, на фоні якого розвиваються його соціальні контакти (насамперед з однолітками). Отримані результати розподілилися таким чином: низька тривожність зафіксована тільки в 2 учнів 8 класу -це 6,7%, та в 1 учня 9 класу -це 3,2%, знижена тривожність зафіксована у 6 учнів 8 класу -20,7% та у 4 учнів 9 класу -12,9т%, підвищена тривожність -31,2% (9 учнів) 8 класу та 35,6% (11 учнів) 9 класу, висока тривожність зафіксована у 41,4% досліджуваних (12 учнів) 8 класу та 48,3% у 15 дев'ятикласників.
Третій фактор -«фрустрація потреби в досягненні успіху» -характеризується несприятливим психічним фоном, який не дає змоги дитині розвивати свої потреби в успіху та досягненні високого результату. Отримано такі дані: низька тривожність -3,4% (1 учень) восьмого класу досліджуваних та 1 учень дев'ятого класу 3,2%, знижена три-
Рис. 1. Результати діагностики рівня шкільної тривожності у підлітків (за методикою Б. Філліпса)
Примітка: а) учні 8 клас (n=29); б) 9 клас (n=31) вожність виявлена у 5 учнів 17,2% восьмикласників та 5 учнів дев'ятикласників -16,1%, виявлена підвищена тривожність учнів восьмого класу -це 34,5% та у 12 учнів дев'ятого класу -38,7%, висока тривожність виявлена у 13 восьмикласників -44,9% та у 13 дев'ятикласників -42%. Четвертий фактор -«страх самовираження», що проявляється в негативному емоційному переживанні ситуацій, які пов'язані із необхідністю саморозкриття, представлення себе іншим, демонстрації своїх можливостей. Низьку тривожність не виявлено в класах досліджуваних, знижена тривожність у 8 класі становить 20,6% (6 учнів) та 12,9% (4 учні) у дев'ятому класі, підвищена тривожність виявлена у 10 учнів -34,5%, та у 11 учнів 9 класу -35,6%, висока тривожність (44,9%) у 13 учнів восьмикласників та у 16 учнів дев'ятикласників -51,5%.
П'ятий фактор -«страх ситуації перевірки знань» -дитина проявляє негативне ставлення і переживання тривоги в ситуаціях перевірки (особливо публічної) знань, досягнень, можливостей. Низька тривожність не виявлена, знижена тривожність -13,7% (4 учні) у 8 класі та 9,7% (3 учні) 9 класу, підвищена тривожність -31,2% у 8 класі та 35,6% у 9 класі, висока тривожність -55,1% у 8 класі та 54,7% у 9 класі.
Шостий фактор -«страх не відповідати очікуванням оточення». Цей фактор орієнтується на значущість інших в оцінюванні своїх результатів, вчинків і думок, тривога стосовно оцінок, які дає оточення, очікування негативних оцінок. Низька тривожність -3,5% у 8 класі та 3,2% у 9 класі досліджуваних, знижена тривожність -13,7% у 8 класі та 6,4% у 9 класі, підвищена тривожність виявлена у 11 восьмикласників -38%, та 10 дев'ятикласників -32,2%, висока тривожність зафіксована у 13 восьмикласників -44,8% та у 18 дев'ятикласників 58,2% досліджуваних.
Сьомий фактор -«низька фізіологічна опірність стресу» -проявляється у зниженні пристосованості дитини до ситуацій стресогенного характеру. Низька тривожність у 8 класі не виявлена, у 9 класі виявлена в 1 учня -3,2% досліджуваних, знижена тривожність -20,7 % у 8 класі та 29,1% у 9 класі, підвищена тривожність -34,5% досліджуваних восьмого класу та 29,1% досліджуваних 9 класу, висока тривожність -44,8% досліджуваних 8 класу та 64,5% досліджуваних 9 класу.
Восьмий фактор -«проблеми і страхи у стосунках з учителями» -характеризується загальним негативним емоційними стосунками з дорослими в школі, знижує успішність навчання дитини. Отримані результати розподілилися таким чином: низька тривожність виявлена тільки у 9 класі 32%, знижена тривожність -3,7% у 8 класі та 9,7% у 9 класі, підвищена тривожність -27,7% у 8 класі та 38,7% у 9 класі, висока тривожність -58,6 % досліджуваних 8 класу та 48,4% 9 класу.
Проаналізувавши результати дітей старшого шкільного віку за методикою «Оцінка рівня шкільної тривожності Б. Філліпса», можемо зробити такий висновок, що загалом рівень тривожності високий та підвищений. Багато дітей бояться і замикаються в собі, тим самим не проявляють свої здібності, знання, творчий потенціал. Це може бути пов'язано з низькою самооцінкою, з відчуттям, що ти не такий, як всі, та через недостатню увагу з боку батьків.
Порівнюючи результати за класами, можемо сказати, що досліджувані під час перебування в одному навчальному закладі, але у різних колективах однолітків, схильні переживати тривожність різного рівня інтенсивності.
Наступний етап дослідження полягав у визначенні рівня реактивної та особистісної тривожності за методикою Ч. Спілбергера -Ю. Ханіна (рис. 2). ПСИХОЛОГІЯ ОСОБИСТОСТІ Результати дослідження показали, що в обох класах досліджуваних було виявлено високий та середній рівень реактивної тривожності, а саме: високий рівень 62,1% (18 учнів) 8 класу та 64,5% (20 учнів) 9 класу, середній рівень зафіксовано у 34,5% (10 учнів) 8 класу та 29,1% (9 учнів) 9 класу. Лише у деяких учнів простежується низький рівень в обох класах 3,4% (1 учень) у 8 класі та 6,4% (2 учні) у 9 класі.
Рис. 2. Результати дослідження рівня реактивної та особистісної тривожності підлітків за методикою Ч. Спілбергера -Ю. Ханіна
Це свідчить про те, що у здебільшого простежується напруга, занепокоєння, нервозність від певних ситуацій, що погано позначається на результатах діяльності. Ймовірно такі дані можна пояснити тим, що під час дослідження атмосфера в класах була неспокійною, тому досліджуванні відчували напруження чи острах.
Отже, реактивна тривожність як емоційний стан характеризується суб'єктивним відчуттям напруження, очікуванням негативного розвитку подій і часто зумовлена неусвідомленим джерелом небезпеки. Вона характеризується відносно стійкою схильністю людини сприймати загрозу власному «Я» в різних ситуаціях, доволі часто неадекватно їх оцінювати та перебільшувати значущість.
Слід підкреслити, що емпіричне дослідження спрямоване на виявлення психологічних особливостей підлітків з різним рівнем тривожності, тобто як стійкої властивості, риси особистості. Реактивна тривожність як стан характеризується емоціями, що переживаються суб'єктивно: напругою, турботою, занепокоєнням, нервозністю. Цей стан виникає як емоційна реакція на стресову ситуацію та може бути різним за інтенсивністю та динамічним у часі.
Як видно з рис. 2, в школярів домінує високий та середній рівні особистої тривожності. Високий рівень особистої тривожності у 8 класі становить 51,7% (15 учнів), у 9 класі -67,6% (21 учень). Середній рівень особистісної тривожності -48,3% -виявлено у 14 восьмиклас-ників та 29,2% 9 дев↔ятикласників. Це говорить про те, що більшість учнів в обох класах схильні до тривожності, яка простежується як індивідуальна риса характеру особистості та проявляється в тенденції сприймати досить широкий спектр ситуацій як загрозливі, відповідати на кожну з них певною реакцією. Швидше за все, такі дані можна пояснити тим, що в підлітковому віці тривожність опосередковується самооцінкою, внутрішніми та зовнішніми конфліктами, також певним статусом серед ровесників.
Отже, особистісна тривожність являє собою підвищену схильність до занепокоєння і тривожних переживань без особливих на те причин. Її поява може бути пов'язана з деякими змінами в гормональному фоні організму людини, а також з тим, що людина привертає до себе загальну увагу і йому від цього неприємно. Якщо порівняти реактивну тривожність і особистісну тривожність школярів, то можна помітити, що в обох класах більшою мірою виражається високий та середній рівень особистісної тривожності. Звідти можна вважати, що в більшості учнів переважатиме особистісна тривожність над реактивною.
Наступним кроком експерименту є визначення рівня поширеності деструктивних станів серед респондентів підліткової групи. З цією метою застосовуємо методику Г. Айзенка «Самооцінка психічних станів» (рис. 3).
З результатів дослідження було визначено, що в обох класах домінує тривожність. Результати проведених досліджень свідчать, що серед підлітків 13-15 років переважає високий рівень тривожності. У 8 класі цей показник становить 55,2% (16 учнів), у 9 класі -54,8% (17 учнів). Для цих дітей переживання емоційного неблагополуччя, пов'язане з передчуттям небезпеки або невдачі. Будь-яка нестабільність, порушення звичного ходу подій може привести до розвитку тривожності. Маскуючи свою тривогу, ховаючи її від дорос- лих та однолітків і навіть від себе, вони самі не знають, що їм потрібно, не можуть звернутися по допомогу, провокують негативне ставлення до себе оточуючих. Це ускладнює і без того важкий внутрішній стан дитини в період підліткової кризи, закріплюючи впевненість у тому, що шляхи до «нормального» життя для них закриті. Одними із частих проявів тривожності в підлітків є апатія, в'ялість, безініціативність. На другому місці нашого дослідження такий тип деструктивного стану, як фрустрованість. За результатами дослідження цей показник сягнув у 8 класі позначки 27,6%, а у 9 класі 29,1%. Відчуття цих дітей при такому стані дуже важкі, йде занурення в глибоку меланхолію, і виникають проблеми зі сном, з'являються утруднення у розумовій діяльності. Депресія проявляється у сумі, безсиллі, усвідомленні невпевненості, безнадійності, тимчасового заціпеніння, відчаю, скутості і апатії. Типова риса фрустрації -це дисбаланс емоцій. Діти емоційніші, ніж дорослі, оскільки вони володіють незначними можливостями пристосування, і ось з цієї причини відбувається емоційна реакція. Фрустрація розрізняється як за психологічним змістом, так і за тривалістю. Психічні стани можуть проявлятись як короткі спалахи агресії, а також депресивні реакції афективного типу, що виражаються в негативному настрої.
Згідно з отриманими результатами 10,4% (3 учні) 8 класу та 12,9% (4 учні) претендують на агресивність. У цих дітей зазвичай низький рівень інтелектуального розвитку, підвищена навіюваність, копіювання, недорозвиненість етичних уявлень. Їм властива емоційна грубість, озлобленість як проти однолітків, так і проти навколишніх дорослих. У таких підлітків спостерігається крайня самооцінка (або максимально позитивна, або максимально негативна), підвищена тривожність, страх перед широкими соціальними контактами, егоцентризм, невміння знаходити вихід з важких ситуацій, переважання захисних механіз- мів над іншими механізмами, регулюючими поведінку. Часто такі підлітки знаходяться по відношенню до офіційного керівництва школи в деякій опозиції, що виражається в їх підкресленій незалежності від вчителів. Вони претендують на неформальну, але авторитетнішу владу, спираючись на свою реальну фізичну силу. Ці неформальні лідери володіють великою організуючою силою можливо тому, що за свій успіх вони можуть використовувати привабливий для всіх підлітків принцип справедливості. Невипадково біля них збираються не дуже розбірливі в цілях і засобах компанії підлітків. Сприяють успіху таких лідерів і уміння безпомилково визначати слабких, тих, хто виявляється беззахисним перед нахабством і цинізмом, особливо, якщо цей цинізм представлений під виглядом морального принципу «виживають сильні, слабкі вимирають». Ригідність притаманна 6,8% (2 учням) 8 класу та 3,2% (1 учневі) 9 класу. Такі діти не змінюють своїх звичок, вони вперто стоять на своїх позиціях, відстоюючи інтереси і тактику в побуті. Такі люди відрізняються підвищеною емоційною чутливістю, вразливістю, довгий час зберігають отриманий емоційний стан. Результати попередніх досліджень свідчать про наявність у досліджуваній вибірці респондентів з високими відсотками небажання зближатись на емоційній основі, високим рівнем тривожності та фрустрованості.
Рис
Доцільно перевірити наявність таких бар'єрів, як сором'язливість та боязливість. З цією метою використовуємо методику Є. Ільїна «Сором'язливість та боязливість». Результати дослідження представлено на рис. 4.
Підсумок даних тесту підтвердив високий рівень емоційного стану «сором'язливість та боязливість» серед підлітків 8 та 9 класів. Цей результат становить: у 8 класі 58,7% (17 учнів) та 64,5% (20 учнів) 9 класу, що ще раз підтвердило нашу гіпотезу про прямий вплив негативних станів як чинників, що впливають на рівень тривожності у підлітків. У цих дітей в незвич-
. 4. Результати дослідження сором'язливості та боязливості підлітків за методикою Є. Ільїна58,70%
34,50%
6,80%
64,50%
32,20%
3,30%
0,00%
10,00%
20,00%
30,00%
40,00%
50,00%
60,00%
70,00%
високий
середній
низький
8 клас (n=29)
9 клас (n=31)
ній ситуації або під час спілкування з іншими дітьми чи дорослими найчастіше з'являється почуття тривоги та пригніченості. Коли люди уважно дивляться на неї, вона почуває себе ніяково й скуто, наприклад, під час знайомства або в ситуації, коли необхідно сказати про щось привселюдно. Сором'язливій дитині набагато зручніше спостерігати за подіями зі сторони, ніж ставати їх безпосереднім учасником. Вони не відчувають надійної батьківської підтримки. Деякі діти відчувають страх перед невдачею, мають обмежені можливості розвитку та практики навичок спілкування, мають мало друзів, страждають від підвищеної тривожності. Так, 10 восьмикласників (34,5%) та 10 дев↔ятикласників (32,2%) належать до середнього рівня емоційного стану. Лише 6,8% (2 учні) 8 класу та 3,3% (1 учень) 9 класу зайняли позицію низького рівня емоційного стану. Ця категорія дітей рідко беруть участь у веселих іграх і змаганнях, які вимагають взаємодії з іншими дітьми, рідко займаються спортом, танцями, музикою або театральним мистецтвом, мають загострене почуття самотності, уважають себе нікчемними і страждають від заниженої самооцінки, не можуть повністю розкрити свій потенціал, оскільки бояться піддатись осуду. Результати дослідження свідчать про те, що в підлітковому віці тривожність залишається гострою проблемою. Отже, сором'язливість та боязливість як стан є притаманним дітям підліткового віку.Рівні розподілу свідчать, що високий рівень склав -61,7%. А це є досить значною проблемою, адже створює вагомі проблеми із налагоджуванням особистих контактів, самопрезентацією, самовираженням, створенням особистого іміджу, знижує самооцінку. Середній рівень склав 33,3%, а це означає, що для того щоб бути успішним, молодим людям потрібно вчитись бути впевненими у собі та брати відповідальність за свої вчинки. Низький рівень сором'язливості притаманний 5% респондентів. Тут притаманний як позитив, так і негатив. Потрібно триматись принципу «золотої середини», адже нахабство, самовпевненість, егоїзм не є помічниками і зазвичай лише ускладнюють відносини та спілкування.Висновки з проведеного дослідження. Для вивчення психологічних особливостей прояву тривожності у підлітків підібрано комплекс методик та проведено емпіричне дослідження. За результатами досліджень було виявлено домінування високого та підвищеного рівня тривожності підлітків. Тривожність становить собою фактор, який визначає поведінку людини в конкретних ситуаціях та загалом. Попри те, що існування феномену тривожності не викликає сумнівів, її прояви в поведінці простежити досить складно. Це пов'язано з тим, що тривожність часто маскується під поведінкові прояви інших проблем, таких як агресивність, залежність і схильність до підпорядкування, облудність, лінощі як результат «вивченої безпорадності», помилкова гіперактивність, відхід у хворобу та інше. Таким чином, реактивна та особистісна тривожність проявляються, коли людина потрапляє в неприємну для неї ситуацію (наприклад, для учня це може бути виконання контрольної роботи, якої він з побоюванням чекав). У цій ситуації негативні психологічні стани, тривожність накопичуються у людини ще задовго до появи неприємної ситуації, і досягає свого максимуму особистісна тривожність у момент, наприклад, коли учень отримає завдання. Реактивна тривожність іноді, залежно від своєї масштабності, може перерости в невроз.Отже, результати нашого дослідження свідчать про те, що в підлітковому віці тривожність залишається гострою проблемою. Тому перспективою подальших досліджень буде розроблення психокорекційної програми зняття тривожності підлітків.ЛІТЕРАТУРА | [
-0.15815016627311707,
-0.07419675588607788,
-0.041377533227205276,
0.03296347334980965,
-0.28891825675964355,
0.04277113080024719,
-0.06289931386709213,
0.2514185905456543,
-0.0875067412853241,
0.21813243627548218,
-0.04720845818519592,
0.24898391962051392,
0.2364404797554016,
0.1255915015... |
MiniCLEAN-360: A liquid argon/neon dark matter detector
2008
Keith Rielage rielagek@lanl.gov
Los Alamos
National Laboratory
MiniCLEAN-360: A liquid argon/neon dark matter detector
The XXIII Conference on Neutrino Physics and Astrophysics IOP Publishing Journal of Physics: Conference Series
13642086200810.1088/1742-6596/136/4/042086for the DEAP/CLEAN collaboration 1 1
MiniCLEAN-360 utilizes 360 kg of liquid argon to detect the nuclear recoil from WIMP dark matter with a projected cross-section sensitivity of 10 −45 cm 2 . To reach this planned sensitivity, a unique modular design is being developed with a spherical geometry to maximize light collection using PMTs. Pulse shape discrimination techniques separate nuclear recoil signal from the electron recoil backgrounds resulting from the beta decay of 39 Ar and Compton scattering of gamma rays. The design allows for the replacement of the target material with liquid neon to examine any signal and backgrounds with a different sensitivity. It also provides research and development for a larger scale low energy solar neutrino experiment using neon (CLEAN: Cryogenic Low Energy Astrophysics with Noble gases) that plans to measure the pp-solar neutrino flux to 1%. Particular attention is being paid to mitigating the background from contamination of surfaces by radon daughters during assembly. The engineering design, radon mitigation plan, and various testing setups are presented. MiniCLEAN-360 anticipates the start of data collection in mid-2009 at SNOLAB in Sudbury, Ontario, Canada.
MiniCLEAN-360 utilizes 360 kg of liquid argon to detect the nuclear recoil from WIMP dark matter with a projected cross-section sensitivity of 10 −45 cm 2 . To reach this planned sensitivity, a unique modular design is being developed with a spherical geometry to maximize light collection using PMTs. Pulse shape discrimination techniques separate nuclear recoil signal from the electron recoil backgrounds resulting from the beta decay of 39 Ar and Compton scattering of gamma rays. The design allows for the replacement of the target material with liquid neon to examine any signal and backgrounds with a different sensitivity. It also provides research and development for a larger scale low energy solar neutrino experiment using neon (CLEAN: Cryogenic Low Energy Astrophysics with Noble gases) that plans to measure the pp-solar neutrino flux to 1%. Particular attention is being paid to mitigating the background from contamination of surfaces by radon daughters during assembly. The engineering design, radon mitigation plan, and various testing setups are presented. MiniCLEAN-360 anticipates the start of data collection in mid-2009 at SNOLAB in Sudbury, Ontario, Canada.
1
The XXIII Conference on Neutrino Physics and Astrophysics IOP Publishing Journal of Physics: Conference Series 136 (2008) 042086 doi:10.1088/1742-6596/136/4/042086 c 2008 IOP Publishing Ltd1
| [
-0.1696167141199112,
0.09890026599168777,
-0.04551665484905243,
0.06076813489198685,
0.11230675876140594,
-0.2231714129447937,
-0.009153110906481743,
0.19521719217300415,
-0.04895346611738205,
-0.034461021423339844,
-0.005995543673634529,
-0.13076770305633545,
-0.04260803014039993,
-0.0007... |
10.1007/978-3-658-30893-3_661
ZusammenfassungSeit mittlerweile fünf Jahren arbeite ich fast ausschließlich im Homeoffice bzw. in virtuellen Teams und habe auch eine wissenschaftliche Arbeit zu diesem Themenbereich geschrieben. Ich war viel unterwegs und habe von allen Ecken der Welt aus gearbeitet, bis mich COVID-19 gezwungen hat, meine Reisen zu unterbrechen. Dies gab mir Zeit, die praktischen wie auch die wissenschaftlichen Erfahrungen zusammenzufassen.Virtuelle Teams zeichnen sich in erster Linie dadurch aus, dass sie meist nur mithilfe von Technologie auf Distanz zusammenarbeiten. Die Etablierung und die Steuerung solcher Teams sind die zentralen Themen dieses Essentials. Neben dieser Definition wurden im ersten Kapitel Faktoren diskutiert, die die Arbeit in virtuellen Teams befördern. Besonders unterstützt werden virtuelle Teams durch Trends der letzten Jahre wie Arbeit 4.0, Outsourcing, besserer Zugang zu Technologie, aber auch durch die Pandemie aufgrund von COVID-19, in deren Folge Firmen zeitweise zu 100 % auf die Arbeit aus dem Homeoffice umgestellt haben. Im zweiten Kapitel wurden Chancen und Risiken durch virtuelle Teams betrachtet. Die wichtigsten Chancen, die sich aus dieser Arbeitsweise ergeben, sind eine international vernetzte Arbeit, durch die Fachkräfte unabhängig vom Standort für weltweit agierende Kunden tätig sein können. Weiterhin könnte die Reaktionsfähigkeit, die Schnelligkeit, die Flexibilität und damit die Agilität eines Unternehmens deutlich gesteigert werden. Mögliche Risiken stellen vor allem die Kosten für die Anschaffung der notwendigen Technologie dar. Diese ist in der Regel nicht günstig, dazu kommt ein hoher Wartungsbedarf. Auch der Datenschutz ist als Risikofaktor zu bewerten. Da die Kommunikation ausschließlich über Technologie erfolgt, gilt es die Kommunikation zu schützen. Für Mitarbeiter kann die höhere Selbstorganisation durch die Arbeit zuhause zusätzliche Belastungen mit sich bringen und für 6
Führungskräfte ist es eine Herausforderung, Mitarbeiter trotz der Distanz zu motivieren. Um die technischen Herausforderungen zu lösen und eine zielgerichtete Zusammenarbeit von virtuellen Teams zu erreichen, wurde im dritten Kapitel eine Reihe von Technologien vorgestellt. Die wichtigsten sind: • Aufgabenverwaltungstool wie OTRS oder Jira • Chatsystem wie RocketChat • Mailserver wie Open Xchange • Notizsysteme wie Joplin oder OneNote • Filesharing wie ownCloud oder onedrive • Gemeinsame Dokumente bearbeiten wie OnlyOffice oder MS Office365 • Meetingmöglichkeiten wie Jitsi oder Zoom Weiterhin wurde festgestellt, dass die Führung und das Verhalten in virtuellen Teams nicht mit jenen in Präsenzteams gleichgesetzt werden können. Daher wurden im vierten Kapitel Meetingformate wie Dailys und Retrospektiven sowie mögliche Arbeitsmethoden diskutiert. Die wichtigsten Erkenntnisse sind: • Virtuelle Teamarbeit kann durch klassische und agile Arbeitsmethoden abgebildet werden. • Wichtig ist die Visualisierung von Arbeit anhand von Boards und Ticketsystemen. • Wichtige Meetingformate sind das Boardmeeting zur Organisation des Softwaretools als Knotenpunkt der Informationen. • Controlling kann durch eine simple Zeiterfassung und einen Health Check durchgeführt werden. • Status-und individuelle One-on-One-Anrufe sind notwendig, um nicht den Kontakt zum Team zu verlieren. • Zuhören statt reden ist in Gesprächen mit Mitarbeitern sehr wichtig. • Platzieren Sie sich als Moderator und fördern Sie die Nutzung von Software zur Steuerung des Teams. • Die Festlegung und die Einhaltung von Rollen sind von wesentlicherBedeutung, zudem sind diese stets zu respektieren. Dezentralisierung von Arbeit in bestimmten Bereichen möglich ist und ich möchte trotz Karriereambitionen noch viel von der Welt kennenlernen und mich flexibel bewegen können. Ich glaube, dass dies für viele Unternehmen möglich ist und ich empfehle jedem, diesem Weg zumindest in kleinen Teilen auszuprobieren, um anderen Arbeitnehmern genauso wie mir eine orts-und zeitflexible Arbeit zu ermöglichen, durch die man vielleicht wirklich irgendwann am Strand, in der Bar oder auch am Skilift arbeiten kann (vgl. Abb. 6.1).Die Erkenntnisse aus Kap. 4 führen zu neuen Herausforderungen für Führungs-
kräfte. So gilt es, neben der eigenen Persönlichkeit auch die aktive Führung
mithilfe von Technologie kennenzulernen bzw. zu erlernen. Kap. 5 gibt dazu
praktische Empfehlungen für Führungskräfte. Die wichtigsten sind:
• Es ist fast nicht möglich, jeden einzelnen Mitarbeiter zu steuern, weshalb die
Steuerung über Gruppenziele und über die Software (Taskboard) zu bevor-
zugen ist.
• Eine Führungskraft sollte die Einführung virtueller Teams durch einen
systematischen Veränderungsprozess begleiten.
Ich hoffe, dass Ihnen das Essential zahlreiche Eindrücke und Impulse vermittelt und
vor allem Spaß beim Lesen bereitet hat. Es enthält neben meiner Praxiserfahrung
auch Erkenntnisse aus meiner Doktorarbeit. Ich persönlich möchte die Arbeit in
virtuellen Teams wie auch im Homeoffice sowie in anderen Ländern nicht missen.
Ich glaube, dass eine vollständige
Abb. 6.1 Virtuelle Arbeit kann von überall durchgeführt werden
| [
-0.08048073947429657,
-0.04222094267606735,
-0.184376060962677,
-0.07503876090049744,
0.06293617188930511,
0.09512709081172943,
-0.003474635537713766,
0.10120704770088196,
-0.03152700886130333,
0.05969959869980812,
0.0060673849657177925,
-0.08930045366287231,
0.07992706447839737,
-0.027254... |
Accredited by Sinta Rank 2 based on Ristekdikti No.10/E/KPT/2019
31/12/2022
Imam Indratno
Universitas Islam Bandung
BandungIndonesia
Atie Rachmiatie
Universitas Islam Bandung
BandungIndonesia
Ferra Martian
Universitas Islam Bandung
BandungIndonesia
Nurrhisma Yuniar
Universitas Islam Bandung
BandungIndonesia
Vermanda Maharani Sonya
Universitas Muhammadiyah Prof Dr Hamka
JakartaIndonesia
Yayu Hizza Anisa
Accredited by Sinta Rank 2 based on Ristekdikti No.10/E/KPT/2019
31/12/20227776D34C160333EF5D8C20836991F55E.org/10.29313/mimbar.v0i0.1Received: 28/10/2022 Reviewed: 10/12/2022 Accepted: 25/12/2022 This work is licensed under a Creative Commons Attribution 4.0 International License Volume : 38 No. : 2 Month : December Year : 2022 Pages : 423-435sustainabilityinclusivenesshalal tourism
The purpose of this study is to identify the potential of sustainability and inclusive components in the development of halal tourism in Alamendah Village.This research focuses on the description of sustainability and inclusiveness based on the criteria and indicators specified.The methodology used is a qualitative method with interactive and descriptive analysis methods.The results of this study indicate that the potential for sustainability and inclusiveness in Alamendah Village has been realized well, but it requires better regulatory and administrative support to realize the sustainable and inclusive halal tourism.
Development of Sustainable Halal Tourism in Alamendah
Village, Bandung Regency
Introduction
Tourism is one of the leading sectors in development in Indonesia (Putri, 2020).Currently, all sectors in development must pay attention to sustainability, as stated in the SDGs document which was also attended by the Vice President of Indonesia (Notonegoro et al., 2019).In addition to being related to sustainability, current development must also pay attention to inclusiveness.Inclusiveness in development has a variety of different definitions, but broadly speaking, inclusiveness in development is how all stakeholders including all levels of society can participate in collaborating and share the benefits of development itself (Fairuza, 2017).These two components are also applied in the development of the tourism sector.Tourism activities have many concepts, one of which is the concept of halal tourism.In the development of halal tourism, the tourism dimension continues to shift.In the past, tourism was an exclusive activity, but now tourism, especially halal tourism, is an inclusive activity.In fact, in the future, halal tourism is expected to become a universal activity that can be enjoyed by all parties, not specifically for certain community groups (Wijayanti et al., 2019).
However, until now the discussion of halal tourism is still focused on mapping the potential, prospects, and challenges (Subarkah, 2018), marketing strategy (Mahardika, 2020) and market analysis (Gilang Widagdyo, 2015), as well as increasing DOI: https://doi.org/10.29313/mimbar.v0i0.10860 the concern and attention of stakeholders and community towards the development of halal tourism (Pratiwi et al., 2018).Then the focus of developing halal tourism is still related to the basic needs of Muslim tourists according to the 2019 Mastercard-Crescent Rating Global Muslim Travel Index, especially numbers 1,2,3,8 and 9, namely halal food, worship facilities, bathrooms with running water facilities as a means of purification and cleaning, private recreational facilities for women and men, and no non-halal services such as serving alcoholic beverages, discotheques or adjacent to gambling resorts (Destiana & Astuti, 2019).There has been no discussion or development of halal tourism that is really related to inclusiveness and sustainability.The development of sustainable and inclusive halal tourism is basically a desire to have a good relationship with God (hablum minallah), good relations between humans (hablum minannas), and good relations with nature (hablum minal alam).
Social capital is often the key to developing a sustainable and inclusive concept.However, social capital can also be an obstacle when there is a strong change in social dynamics (Scheyvens & Biddulph, 2018).The first step that can be taken in developing tourism, especially in rural locations, is to explore its potential (Muslim, 2016).One of the tourist villages that is trying to implement the concept of halal tourism is Alamendah Village.In 2011, Alamendah Village by the local government was designated as one of the 10 Tourism Villages in Bandung Regency.Some of the tourist destinations that are served are Kawah Putih, Ranca Upas Campground, Ciwidey Valley and EmTe Highland Resort.Determination as a tourism village creates employment opportunities for the community such as homestay owners and managers, workers at resorts/tourist attractions, traders, tour guides, and ontang-anting drivers (special cars to climb to Kawah Putih crater).
As previously explained, the development of halal tourism must contain the value of sustainability and inclusiveness.However, currently, the terminology of sustainability and inclusiveness in tourism activities in Alamendah Village still feels strange to most stakeholders involved in tourism development, especially local communities and business actors.However, this does not mean that the values of sustainability and inclusiveness have not been applied to tourism activities in Alamendah Village.This study seeks to provide a description of the potential for sustainability and inclusiveness, which is particularly related to tourism development activities in Alamendah Village.In addition, this study seeks to provide a new paradigm that halal tourism is not only related to tangible things such as infrastructure and food and beverages, but also more to the philosophy of life and the concept of inclusive thinking.Mapping the potential for sustainability and inclusiveness is important to be the first step in the development of halal tourism to be carried out, so that the basic value of halal tourism, namely goodness for all nature (rahmatan lil 'alamin) can be realized.This research can help the stakeholders involved to take the next step in developing halal tourism, be it at the regulatory, administrative, community empowerment, and spatial planning levels.
Research Method
The location of this research is in Alamendah Village, Rancabali District, Bandung Regency.The Alamendah Village was chosen as the research location because the tourism potential that can be developed is very diverse.All levels of society and various local communities in it have also participated in tourism development.This is evidenced various awards gained from the Ministry of Tourism and Creative Economy, such as being included in the top 50 Indonesian Tourism Village Awards in 2021 and having received a certificate as a Sustainable Tourism Village on 27 October 2022.Currently, Alamendah Village has implemented the concept of Muslim-friendly tourism, but is still open to every race, ethnicity, religion, and community diversity.This is unique in the development of halal tourism in the village.The research method used is a qualitative research method.This method is used as a tool to identify the potential for sustainability and inclusiveness of halal tourism development in Alamendah Village.The primary data in this study were obtained using in-depth interviews with several representatives of the community, such as the village government, tourism village managers, religious leaders, and business actors.In addition, documentation and observations were also carried out to complete the need for potential identification
The secondary data in this study are related journals from previous research as research reference materials and reports on the assessment of sustainable tourism certification owned by Alamendah Village as an overview of the condition of tourism potential.The sampling method used in this study was purposive sampling with the respondents being representatives are from the village government, the chairman and members of DAWALA or the Alamendah Tourism Village Manager, business actors in Alamendah Village, and local religious leaders.The respondents were chosen because they were considered to know the potential conditions possessed by Alamendah Village in the development of halal tourism and directly related to its development.The analysis done was the interactive and descriptive analysis of the results of interviews, documentation, and observations that have been carried out.The sustainability variables used in this study generally refer to the three pillars of sustainable development, namely economic sustainability, social sustainability, and environmental sustainability, while the inclusivity variable emphasizes on collaboration between stakeholders with indicators of the same interpretation and goals, management, commitment, trust, reciprocal relationships, communication and a collaborative environment.
Results and Discussion
The results of this study are divided into two discussions, namely considering the potential for sustainability in tourism development in Alamendah Village and the potential for inclusiveness in the same way.The sustainability component in question is seen based on the criteria and indicators in the Regulation of the Minister of Tourism and Creative Economy Number 9 of 2021 concerning Guidelines for Sustainable Tourism Destinations.While the potential for inclusiveness is seen based on the interpretation or goals of respondents in developing halal tourism, management in developing halal tourism, trust between stakeholders, reciprocal relationships that occur between stakeholders, communication and collaboration between stakeholders.
Sustainability Potential in Alamendah Village
Alamendah Village is a tourism village with various potentials.Basically, tourist attractions in Alamendah Village are agricultural activities and nature attractions such as strawberry plantations and picking, Kawah Putih, coffee plantations, coffee trips, Ranca Upas, Curug Awi Langit, Patuha Pinus Land, Punceling Pass, Curug Padjajaran, Ciwidey Valley, Emte Highland, Cigadog Lestari, and Patuha Bike Park.Socially and culturally, the local community in Alamendah Village really appreciates diversity, be it race, ethnicity, religion, and so on.Thus, all levels of society are very open to collaborate in tourism development.
Based on the Minister of Tourism and Creative Economy Regulation Number 9 of 2021 concerning Guidelines for Sustainable Tourism Destinations, the value of sustainability is in accordance with the three pillars of sustainable development, namely economically and socially sustainable, culturally sustainable, and environmentally sustainable.The three components then have further criteria and indicators.The following is a table of criteria and indicators assessment of sustainability found in Alamendah Village:
Support for the community
There is a mechanism that connects tourism business entities with the community; the existence of a mechanism that connects visitors with the community; there is a persuasive effort to involve the community in tourism activities.
Society in general is now much involved in tourism activities.For example, being a business actor, being a performer at a local festival, an artist, and so on.People can also interact directly with visitors and vice versa.
Prevention of exploitation and discrimination
There are published practices, programs and legislation to prevent commercialization and exploitation, as well as sexual harassment, or other forms of abuse against children, youth, women and minority groups.
In an effort to prevent exploitation and discrimination against certain groups, the village government and all levels of society follow the applicable regulations from the district, provincial, and central governments.All parts of the village community also strongly avoid cases as above from happening, with mutual respect and respect as do the values of religious moderation.
Owner and user rights
There are laws and regulations regarding ownership and acquisition rights that are documented and enforced.Stakeholders can be the government or the private sector, they must comply with the rights of the community.Decision making must go through public consultation, be informed in advance and well socialized, not changing the residence and providing profit.Laws and regulations also protect users and access rights to critical resources.
Regarding the rights of ownership and users, the village government and all levels of society follow the applicable rules and policies, be it from district, provincial, or central governments.
7
Safety and security Security and health services are available; the existence of a system to identify the needs of visitors in accessing security and health services; periodic inspection of facilities to ensure the safety and health of services.
Security and health services are readily available.Both facilities are located in the village office area as the village center, so they are easily accessible by anyone.The activities have been going well so far.
Access for all
The existence of standards or rules in accessing tourist facilities; there is consistent implementation of standards; the existence of a system to identify the carrying capacity of tourism facilities; the existence of a program to improve access; availability of information related to accessibility to various facilities; information regarding the accessibility details.
Rules for accessing tourist facilities are available both in writing and orally.The program to increase access is also carried out by the village government, so that now all parties can access facilities and tourist destinations safely and comfortably.
Information about these facilities is also available at the DAWALA office.The interpretation of the tourism potential aspects contained in Alamendah Village is available both on the village website, as well as on the tourist village social media platform.The language used is Indonesian, so it can be understood both by local people and visitors from outside.
Environmental Sustainability 1
Sensitive environmental protection A system is in place to monitor, measure and respond to tourism impacts on the natural environment, to conserve ecosystems, habitats and species, and to prevent the entry and spread of invasive alien species.
Efforts to monitor and minimize the impact of tourism activities are already in place.One of the efforts is to control the number of tourist arrivals every time.Ecosystem and habitat conservation is carried out by following the prevailing rules and policies.
Management of visitors to natural sites
There is a system for managing visitors in and around natural sites, which takes into account the
The management of visitors is carried out by the tourism village manager on a regular basis, so that DOI: https://doi.org/10.29313/mimbar.v0i0.10860characteristics, capacities and sensitivities of these natures and seeks to optimize visitor movement and minimize their adverse effects.Guidance for visitor behavior on sensitive sites is provided to visitors, travel operators and guides before and during their visit.tourism activities are well monitored and do not exceed the carrying capacity.This is part of an effort to minimize the impact of tourism activities.The visitor behavior guide is given orally by the tour guide before the activity takes place.
3
Interaction with wildlife There is a system in place to ensure compliance with local, national and international laws and standards for interacting with wildlife.In interactions with free-moving wildlife, must take into account cumulative impacts, non-invasive and fully responsible to avoid adverse effects on animals and on the viability and behavior of populations in the wild.
The village government and tourism village managers ensure that all tourism activities that take place are in accordance with the legislation related to the wild life in the vicinity.Interaction with wildlife is part of tourist attractions, such as bird watching using a telescope or binoculars.
4
Species exploitation and animal welfare Systems are in place to ensure compliance with local, national and international laws and standards that seek to ensure animal welfare and species conservation (animals, plants and all living organisms).Also are the systems related to the harvesting or capture, trade, exhibition and sale of wild life species and their related products.
Laws governing species exploitation and animal welfare follow the prevailing rules and policies of district, provincial, and central governments.Efforts to comply with these rules and policies can be ascertained to take place.
5
Energy conservation There are targets set to reduce energy consumption, increase the efficiency of its use, and also increase the use of renewable energy.The destination has a system in place to encourage enterprises to measure, monitor, reduce and publicly report their contribution to these targets.
The target set to reduce energy consumption that already exists is the management of animal manure into biogas.In addition, in the near future, Alamendah Village will also participate in an assessment to achieve an award as a transportation-friendly village.
6
Water governance There are efforts to encourage business entities to measure, monitor, report publicly and manage water use.Water risks at the destination are assessed and documented.
Efforts
to encourage tourism business actors in managing water use are carried out directly by related parties, for example BPOM, Puskesmas ( health center), halal certification institutions, etc.
7
Water quality There is a system to monitor the quality of water for drinking, recreational and ecological purposes using normalized standards.Monitoring results are publicly available, and destinations have systems in place to respond to water quality issues.
Water quality has been checked, but has not been carried out regularly.In general, the water quality is already good because it is close to the Mount Patuha springs.However, some business owners whose location is lower than the springs do not dare to use local water for consumption because they are worried that it will be contaminated with agricultural chemicals.
8
Waste water management There are clear and enforced guidelines for the placement, maintenance and testing of discharges from septic tank and wastewater treatment systems.
Wastewater treatment is currently running as it should.9
Solid waste management There is a system for measuring and reporting the waste generated and setting targets for reducing it.The destination ensures that solid waste is properly treated and diverted from temporary or final disposal sites, by providing a recycling collection system that effectively separates waste by type.
There is no comprehensive solid waste management program in each location, so some local people still manage their waste by burning.However, for several large-scale businesses such as Warung Kopi Gunung, they have collaborated with the district environmental office to manage the solid waste generated regularly once a week.
GHG emissions and climate change mitigation
Have targets to reduce greenhouse gas emissions, and implement them and report on policies and mitigation actions.
Efforts to reduce the effect of greenhouse gases have been carried out by carrying out animal feed efficiency activities, efforts to reduce the carbon footprint of motorized vehicles, etc.
11 Low impact transportation Have targets to reduce transportation emissions from travel to and within destinations.Increasing sustainable use of lowemission vehicle and recommend active travel (walking and cycling).
In the near future, Alamendah Village will also participate in an assessment to achieve an award as a transportation-friendly village.In addition, tourism activities are carried out by walking and cycling.
12 Light and noise pollution Guidelines and regulations are in place to minimize light and noise pollution.Business actors have to follow these guidelines and regulations.
Rules and policies regarding light and noise pollution follow the district, provincial, and central governments.
The village government and all levels of society are trying to minimize the impact.
Source: Analysis Result (2022)
The Potential for Inclusivity in Alamendah Village
Inclusive tourism development is an approach currently used by the Ministry of Tourism and Creative Economy.Tourism activities are often understood as an exclusive development sector (Biddulph & Scheyvens, 2018).What is meant by exclusive is that in tourism activities, often some parties who are considered marginal are not involved in the development of tourism itself, sometimes local communities are also included in the group.In inclusive tourism development, it means that steps need to be taken to be able to involve all components contained in the development location without exception, and ensure that the benefits derived from tourism activities developed can be felt by all parties involved.Halal tourism development also basically provides the same obligation, that this activity should be an inclusive activity for all tourists, not exclusive only for certain groups (Meirezaldi, 2020).This means that in its development efforts it is also necessary to have good collaboration with all components of human resources in the development location.Inclusiveness in tourism development basically emphasizes collaboration and fair and broad benefits.Indicators or components of inclusive tourism development consist of the same interpretation and goals, management, commitment, trust, reciprocity in relationship, communication and a collaborative environment (Fairuza, 2017).The following is a description of the condition of indicators or components of inclusive halal tourism development in Alamendah Village: DOI: https://doi.org/10.29313/mimbar.v0i0.10860This happens because the benefits derived from tourism activities are increasing and expanding.Thus, all stakeholders continue to strive to increase the positive value that has been obtained from current tourism activities.4
Trust Trust is the basic capital to be able to work together with others (Rosiana et al., 2018).This is trust between actors involved in the development of halal tourism in carrying out their roles and responsibilities.
The government has high trust in other stakeholders, including local communities, and even has the perspective that without their involvement, the development of halal tourism will not work.Likewise, business actors, tourism village managers, religious stakeholders, and local communities have high trust in the village government as a regulator and owner of power in developing tourism.So that they are obedient to all policies and decisions taken by the government regarding tourism development.5
Reciprocal relationship Advantages and interrelationships between the actors involved.
Perspective of village government and tourism village managers:
The government is only a regulator whose function is to provide direction, but the role of the surrounding community and other actors is very important.In addition to being based on descriptive assessments of the indicators or components of inclusive halal tourism development in Alamendah Village, based on the results of in-depth interviews conducted with respondents, generally all levels of society are actors and are fully involved in the development of halal tourism.The social component is a very strong added value and capital in Alamendah Village.The social component becomes the foundation of sustainability in the economic and environmental components in this Village.In the end, the tourism activities carried out aim to provide broad benefits to all levels of society.A well-established collaboration in Alamendah Village is shown more clearly by the reciprocal relationship felt by stakeholders.Local business actors have tried to take advantage of the original products from Alamendah Village itself.In addition, large-scale business actors are also trying to absorb labor from the local community, namely the best village youths.Gender equality is also considered with the optimal absorption of female workers.
Related to the application of halal values, inclusiveness is also seen in the economic activities that occur as part of tourism in Alamendah Village.Small-scale and large-scale business actors certainly pay attention to symbolic matters such as the availability of places of worship, prayer tools, ablution places, separation of male and female facilities such as toilets, and so on.However, on average, these business actors consider that symbolic material things like that are the basic facilities that should be available at tourist attractions, not because of the halal tourism label that Alamendah Village wants to apply.Halal values are actually reflected in intangible things such as the way of working and the philosophy of life of business actors, namely "sincere" and "humanizing humans".The business people seem very embracing and appreciating their employees, so they also serve visitors in a very friendly and warm manner.Religious leaders in Islamic boarding schools in Alamendah Village also highly uphold religious moderation.The key to their Islam is to stick only to the Qur'an, hadith, ijma', qiyas, and ijtihad.Related to the application of halal values, inclusiveness is also seen in the economic activities that occur as part of tourism in Alamendah Village.Small-scale and large-scale business actors certainly pay attention to symbolic matters such as the availability of places of worship, prayer tools, ablution places, separation of male and female facilities such as toilets, and so on.However, on average, these business actors consider that symbolic material things like that are basic facilities that should be available at tourist attractions, not because of the halal tourism label that Alamendah Village wants to apply.Halal values are actually reflected in intangible things such as the way of working and the philosophy of life of business actors, namely "sincere" and "humanizing humans".The business people seem very embracing and appreciating their employees, so they also serve visitors in a very friendly and warm manner.Religious leaders in Islamic boarding schools in Alamendah Village also highly uphold religious moderation.The key to their Islam is to stick only to the Qur'an, hadith, ijma', qiyas, and ijtihad.One of the values held by local religious stakeholders who can show their religious moderation is "Business is interfaith, in cross-madzhab religions, in cross-sectoral madzhab".The students are taught to keep thinking about the life of the world, so they run an agricultural business.Cross-religious means the establishment of agricultural supply chain cooperation from the results of Islamic boarding schools to non-Muslim-owned enterprises.Cross-madzhab means that they really appreciate the differences in the way of worship among Muslims.Finally, cross-sectoral shows the obedience of religious stakeholders and their followers to the prevailing rules and constitution.In addition, culture is also highly valued and even preserved.Local religious leaders have the perspective that culture is part of art, not a complete belief, such as koko clothes, pangsi clothes, traditional activities, even the call to prayer are products of art, so they are also included as cultural products.So, if shown in the form of a diagram, the position of inclusiveness in Alamendah Village has been built as a value of religious moderation.
Development of Halal Tourism in Alamendah Village
Based on the results of the analysis that has been done, in general it can be concluded that the social component is a strength and advantage for Alamendah Village in the development of halal tourism.This means that the community is the main focus and actor in achieving the successful development of halal tourism.To apply the concept of sustainability in the development of halal tourism, village governments and tourism village managers can start implementing community-based halal ecotourism.Basically, the concept of community-based ecotourism is widely applied in developing countries.This concept emphasizes that the community has a significant share in tourism activities.This concept talks about how the profits earned are used for the community and how to build cooperation and partnerships between the community and outsiders.This concept is also applied with the aim of minimizing the gap between the government's plans to develop tourism and the fact that people are more motivated by their own social values.Regarding this, the concept of community-based ecotourism contains a very dominant value of inclusiveness.This concept provides opportunities for rural communities to DOI: https://doi.org/10.29313/mimbar.v0i0.10860apply their social values in tourism development.Halal that meant in the community-based ecotourism concept is a new combination that is suitable to be applied, because basically the halal concept in tourism is focused on improving the components of cleanliness, health, security, and environmental comfort based on universal Islamic values.However, to be implemented in Alamendah Village, many improvements are still needed, such as the provision of supporting facilities and infrastructure and the readiness of human resources in facing the development of the concept.Based on the previous analysis, several things can be done as follows: 1) Focus on empowering human resources in advance.This can be done with the first step, namely identifying how prepared all stakeholders are involved in the implementation of community-based halal ecotourism development, be it village governments, tourism village managers, and various community components.This identification in real time can be done with the help of neuroscience and electroencephalography (EEG) technology; 2) If the community has good preparedness (marked by the presence of attention, interest and motivation towards the development of community-based halal ecotourism) then the next step is to prepare supporting infrastructure that is still lacking.However, if the community does not yet have this preparedness, it is necessary to have an effort to sit together between the village government, the tourism village manager, all components of the community, and be assisted by a third party as a cogwheel who initiates and supervise the course of this communication so that it can run in two directions and achieves the same perspective; 3) After having accordant goals, regular training can be carried out on various components of community-based halal ecotourism development to stakeholders who are directly involved in tourism activities.However, the general public who are not directly involved can also take part in the training in order to motivate the community in the future to be involved in tourism activities; 4) Prepare infrastructure that is still lacking, such as the availability of good quality water.Abundant water, but raising concerns about contamination of agricultural chemicals on local water availability can be treated by implementing organic farming.The important thing in implementing organic farming is how to ensure the presence of adequate organic matter in the soil, determine the crop rotation by determining the agricultural crop cycles and timing, conduct conservation by reducing the potential for water runoff and erosion due to water flow, pay attention to irrigation systems and control pest populations; 5) In relation to solid waste management, basic waste management methods such as 3R can be applied since the source of the waste is generated, be it in homes, tourist attractions, offices, restaurants, hotels and other types of lodging, as well as other sources.Waste that can be recycled can be used by the community as raw material for handicrafts.It already exists and can be disseminated to other communities.Then the remaining solid waste can be treated in cooperation with private business entities to manage it.There needs to be a regulation from the village government regarding this, as well as a third party from the village internal as an evaluator who monitors and supervises the operation of this system.In addition, the community also needs to be educated on periodically to increase people's motivation in managing the solid waste; 6) The last and most important thing is to apply human values and advantages to every tourism development activity conducted so that the concept of 'rahmatan lil 'alamin' (blessing for the worlds) can be felt by all stakeholders, and the relationship between humans and nature can also be maintained.
Conclusions
The potential of sustainability and inclusiveness in the development of halal tourism in Alamendah Village has basically been going well in each of its components.Efforts are needed to equalize perceptions among stakeholders to increase the positive value of each component of sustainability and inclusiveness in question.Regarding the development of halal tourism itself, the existing potential for sustainability and inclusivity can be used as a strong capital so that it only requires good regulatory and administrative components to perfect it.
Figure 1 .
1
Figure 1.inclusivity Diagram in Alamendah Village
Table 1 Criteria and Indicator Assessment of Sustainable Tourism in Alamendah Village Based on Minister of Tourism and Creative Economy Number 9 of 2021
1NoCriteriaIndicatorField FactsEkonomic dan Social Sustainability1Measuringtourism'seconomicThere is a program to collectPrograms for collecting economiccontributioneconomic data; an annual report ondataintheformoftotalthe direct and indirect economicexpenditures,employment,contribution of tourism to theinvestment and distribution ofvillage; economic data such as totaleconomic benefits as well as annualexpenditure,employment,reports on direct and indirectinvestment and distribution ofeconomic contributions to villageseconomic benefits in the village.already exist, but have not beencombined and in a formal form suchas reports.2Job and career opportunitiesThe existence of courses or skillsTraining is carried out regularly,training on a regular basis needed ineither through local governmentdeveloping tourism; agreementsassistance or assistance from thewith local tourism business entitiesprivate sector and academics. Small,to provide job opportunities for localmedium to large business actors incommunities; pay attention toAlamendahVillagealsoworkgender equality, disability, youth,together to be able to takeminorities,etc.;thereisaadvantage of local people as theirmechanism for receiving complaintsemployees. Both women and menabout employment.get the same job opportunities.
DOI: https://doi.org/10.29313/mimbar.v0i0.10860
Table 2 Description of the Conditions of Inclusive Halal Tourism Development Components in Alamendah Village
2NoIndicatorDiscriptionField Facts1Interpretation and Colective GoalsMatching goals is the key and thePerspective of village governmentfirst step in building collaboration onand tourism village managers:the development of inclusive halalThe concept of halal tourism istourism (Nurizwan & Dewi, 2018).basically still confusing, because theregulationsfromthenationalgovernment are also less clear,giving rise to various interpretations.However, to develop halal tourismthe most important thing is how toincrease public awareness andinvolve all components of society inits development.Perspective of the business actor :The average business actor who triesto understand the concept of halaltourism interprets its developmentas more symbolic and tangiblethingssuchasfarfromenvironmental pollution, there is aplace for washing hands, close toplaces of worship, has many toilets,there is a place for ablution, thereare prayer tools, there is a Qibladirection, a restaurant or food stallmust be halal certified.Perspectiveofthereligiousstakeholder :The concept of halal tourism that isunderstood is tourism in which allaspects of its development includethings that are good and far fromthings that are haram.Perspective of the local community:People do not fully understand thetrue concept of halal tourismbecause they think that if there aredifferent sources of information,thentherewillbedifferentperspectives.2GovernanceManagement in the development ofPerspective of village governmentinclusive halal tourism. How clear isand tourism village managers:the involvement of all componentsPerspective of the business actor :and their respective responsibilities.The average business actor certainlyconsiders them to be part of thedevelopment of halal tourism inAlamendah Village. In addition, theyconsider the concept of halal tourismto be an added value because it canbe a branding strategy for theirproducts.Perspective of the religious leader :Religious stakeholders also havealmost the same perspective asbusiness actors. Local Islamicboarding schools make their place asa tourist destination. For religiousstakeholders, world affairs are alsoimportant, because currently we areliving in the world, and utilizingtourism activities is a potential thingto meet the worldly needs of thecommunity in Islamic boardingschool.
Halal Tourism: Definition, Justification, and Scopes towards Sustainable Development. M S E Azam, M A Abdullah, D A Razak, International Journal of Business, Economics and Law. 1832019
Introducing inclusive tourism. R Biddulph, R Scheyvens, 10.1080/14616688.2018.1486880Tourism Geographies. 2042018
I C Choirunnisa, M Karmilah, 10.30659/jkr.v2i1.20446Strategi Pengembangan Pariwisata Budaya. 2022289
R Destiana, R S Astuti, Pengembangan Pariwisata Halal Di Indonesia Riska. COPAS: Conference on Public Administration and Society. 201901
Kolaborasi antar Stakeholder dalam Pembangunan Inklusif pada Sektor Pariwisata ( Studi Kasus Wisata Pulau Merah di Kabupaten Banyuwangi ). M Fairuza, 2017Kebijakan Dan Manajemen Publik Volume5
Analisis Pasar Pariwisata Halal Indonesia. Gilang Widagdyo, K , The Journal of Tauhidinomics. 112015
Lombok as An Indonesian Halal Travel Destination. H Haris, M Nashirudin, 10.22515/shirkah.v4i3.277Shirkah: Journal of Economics and Business. 432019
Strategi Pemasaran Wisata Halal. R Mahardika, 10.47971/mjhi.v3i1.187Mutawasith: Jurnal Hukum Islam. 312020
O Meirezaldi, 10.2991/aebmr.k.201116.027Halal Tourism Industry in Indonesia: 7(3). 2020
Economic Community Empowerment Through Tourist Village Development. MIMBAR. A Muslim, 10.29313/mimbar.v32i2.1839Jurnal Sosial Dan Pembangunan. 3223432016
Dinamika Pembangunan Nasional di Era Pandemi. M Notonegoro, R Eko, B Prasetio, M E Sakti, D Nasution, S Ip, 2019
Dynamic Governance Dalam Pengembangan Pariwisata Di Kawasan Resort Pengelolaan Hutan Mangunan Kabupaten Bantul. S Nurizwan, U Dewi, Jurnal Natapraja: Kajian Ilmu Administrasi Negara. 622018
Strategi Komunikasi dalam Membangun Awareness Wisata Halal di Kota Bandung. S R Pratiwi, S Dida, N A Sjafirah, 10.24198/jkk.v6i1.12985Jurnal Kajian Komunikasi. 61782018
Pengaruh Pariwisata Terhadap Peningkatan Kota Surakarta. L R Putri, Cakra Wisata. 2112020
D Rosiana, A Djunaidi, I L Setyono, W Srisayekti, 10.29313/mimbar.v34i2.3650Social Experience and Trust on Prisoners and Non-Prisoners. MIMBAR : Jurnal Sosial Dan Pembangunan. 201834
Inclusive tourism development. R Scheyvens, R Biddulph, 10.1080/14616688.2017.1381985Tourism Geographies. 2042018
Potensi dan Prospek Wisata Halal Dalam Meningkatkan Ekonomi Daerah (Studi Kasus: Nusa Tenggara Barat). A R Subarkah, 10.22219/sospol.v4i2.5979Jurnal Sosial Politik. 42492018
S Umiyati, M H Tamrin, Collaboration Of Stakeholders In The Development Of Halal Tourism In Malang City Of East Java Indonesia In Technology Era 4.0. Systematic Reviews in Pharmacy. 202011
Past, Present, and Future Perspectives on The Concept of Halal Tourism. A Wijayanti, H Widyaningsih, M Faturrahman Hakim, M Arif Fiyan, 10.2991/isot-18.2019.72019. Isot 2018259
| [
0.10035344958305359,
0.07469777762889862,
-0.09387868642807007,
0.021358177065849304,
-0.1525464653968811,
-0.020651614293456078,
-0.1022566556930542,
-0.05248580873012543,
-0.000264451140537858,
0.010193758644163609,
0.12360713630914688,
-0.23083136975765228,
0.01777936890721321,
0.042030... |
"Similitude in Modern Pharmacology": two decades of studies contributing to the scientific basis of the homeopathic healing principle
Marcus Zulian Teixeira marcus@homeozulian.med.br
Faculdade de Medicina
Departamento de Psiquiatria -São Paulo (SP)
Universidade de São Paulo, Hospital das Clínicas
Brazil
"Similitude in Modern Pharmacology": two decades of studies contributing to the scientific basis of the homeopathic healing principle
9FD0B873702DE67B28B442195CA8D61110.1590/1806-9282.20211362Received on December 27, 2021. Accepted on January 09, 2022.
LETTER TO THE EDITORDear Editors, Homeopathy is based on the following four scientific pillars 1 : principle of cure by similars, proving of medicinal substances on healthy individuals, use of dynamized doses, and prescription of individualized medicines.Although great importance was attributed to dynamized doses (ultra-high dilutions), the first two pillars are the fundamental premises of the homeopathic epistemological model, remaining to individualized medicine the essential condition to awakening the therapeutic response.In the systematization of the homeopathic method of treatment, Samuel Hahnemann based the "principle of cure by similars" (principle of therapeutic similitude) on the careful observation of the effects of medicines on human health.In the essay 2 that inaugurated homeopathy in 1796 and in paragraphs 59 and 65 of the Organon of Medicine 3 , he describes the pharmacological effects of dozens of palliative drugs of his time, discriminating the "direct primary action of drug" and the consequent and opposite "indirect secondary action of the body," evidencing the new principle of cure proposed:
[...] Excessive vivacity follows the use of strong coffee (primary action), but sluggishness and drowsiness remain for a long time afterwards (reaction, secondary action), if this be not always again removed for a short time by imbibing fresh supplies of coffee (palliative).After the profound stupefied sleep caused by opium (primary action), the following night will be all the more sleepless (reaction, secondary action).After the constipation produced by opium (primary action), diarrhea ensues (secondary action); and after purgation with medicines that irritate the bowels, constipation of several days' duration ensues (secondary action).And in like manner it always happens, after the primary action of a medicine that produces in large doses a great change in the health of a healthy person, that its exact opposite, when, as has been observed, there is actually such a thing, is produced in the secondary action by our vital force.(Organon of Medicine, paragraph 65) 3 In paragraph 63 of the Organon of Medicine 3 , Hahnemann suggests a physiological explanation for the principle of therapeutic similitude (primary action of the drug followed by secondary and opposite action of the body), justifying its universal mechanism of action of drugs (biphasic action of drugs) on the automatic manifestation of "our life-preserving power" or "homeostasis" according to modern physiology: Every agent that acts upon the vitality, every medicine, deranges more or less the vital force, and causes a certain alteration in the health of the individual for a longer or a shorter period.This is termed primary action.[…].To its action our vital force endeavors to oppose its own energy.This resistant action is a property, is indeed an automatic action of our life-preserving power, which goes by the name of secondary action or counteraction.(Organon of Medicine, paragraph 63) 3 Associating his empirical observations with hundreds of reports of involuntary homeopathic cures described in the literature and employing the inductive Aristotelian reasoning (modus ponens), Hahnemann enunciates the "principle of cure by similars" (Organon of Medicine, paragraphs 24-7) 3 : any medicine that cause, in their primary action, certain signs and symptoms in healthy individuals can be used, in their secondary action, to cure similar signs and symptoms in sick individuals (similia similibus curentur).
Therefore, the homeopathic method of treatment employs the secondary action or vital reaction of the body for therapeutic Rev Assoc Med Bras 2022;68(3):303-307 purposes by administering to ill individuals drugs that cause similar symptoms in healthy individuals in order to awaken a healing reaction of the body against their own disturbances or diseases.
By emphasizing that such secondary action of the body (vital reaction) is observed "in each and every instance with no exceptions" with ponderable or infinitesimal doses in both healthy and ill individuals, Hahnemann raised the principle of therapeutic similitude to the level of a "natural law of cure" (Organon of Medicine, paragraphs 58, 61, 110-2) 3 .
In contrast, demonstrating the occurrence of evident worsening of disturbances or diseases after ceasing the palliative effect of drugs with contrary action to symptomatic manifestations ("principle of cure by contraries") (Organon, paragraphs 57-61) 3 , Hahnemann reinforces the validity of homeopathic treatment according to the deductive Aristotelian reasoning (modus tollens) or "mode that affirms by denial": Important symptoms of persistent diseases have never yet been treated with such palliative, antagonistic remedies, without the opposite state, a relapse -indeed, a palpable aggravation of the malady -occurring a few hours afterwards.For a persistent tendency to sleepiness during the day the physician prescribed coffee, whose primary action is to enliven; and when it had exhausted its action the day -somnolence increased; -for frequent waking at night he gave in the evening, without heeding the other symptoms of the disease, opium, which by virtue of its primary action produced the same night (stupefied, dull) sleep, but the subsequent nights were still more sleepless than before; […] -weakness of the bladder, with consequent retention of urine, was sought to be conquered by the antipathic work of cantharides to stimulate the urinary passages whereby evacuation of the urine was certainly at first effected but thereafter the bladder becomes less capable of stimulation and less able to contract, and paralysis of the bladder is imminent;with large doses of purgative drugs and laxative salts, which excite the bowels to frequent evacuation, it was sought to remove a chronic tendency to constipation, but in the secondary action the bowels became still more confined; [...] How often, in one word, the disease is aggravated, or something even worse is effected by the secondary action of such antagonistic (antipathic) remedies, the old school with its false theories does not perceive, but experience teaches it in a terrible manner.(Organon of Medicine, paragraph 59) 3 According to the modern pharmacology, the "primary action" described by Hahnemann corresponds to the "therapeutic, adverse, and side effects" of conventional drugs, while the "secondary action" corresponds to the "rebound effect" or "paradoxical reaction" of the body, observed after discontinuation of several classes of drugs that act contrary (palliative or antipathic) to the signs and symptoms of diseases.
By definition, the term "rebound" is defined as the reversal of response upon withdrawal of a stimulus, while "rebound effect" means the production of increased negative symptoms when the drug ends or the patient no longer responds to it: if a drug produces a rebound effect, the condition it was used to treat may come back even stronger when the palliative drug is withdrawn (discontinued) or loses effectiveness (development of tolerance or tachyphylaxis).
The rebound effect manifests itself at different intervals (hours to weeks) after the end of the biological effect of the drug (pharmacological half-life), and its duration also varies.The rebound effect presents an intensity or frequency a few times higher than the corresponding baseline symptoms suppressed by the primary action of the antipathic drug.Although the rebound effect only occurs in a minority of susceptible individuals, it becomes an epidemiological concern when considering the exceedingly broad use of palliative treatments by the population.
Following the deductive Aristotelian reasoning employed by Hahnemann to validate the homeopathic healing principle, since 1998, we have been scientifically substantiating the "similitude in modern pharmacology" through the systematic study of the rebound effect (paradoxical reaction) of many classes of drugs [4][5][6][7][8][9][10][11][12][13][14] , confirming the homeopathic postulate and the principle of similitude: a universal occurrence of strong secondary and opposite action of the body after ceasing the primary action of the drugs (Figure 1).
Illustrating the rebound phenomenon [4][5][6][7][8][9][10][11][12][13][14] , it is observed that drugs classically used for the treatment of angina pectoris (e.g., β-blockers, calcium channel blockers, and nitrates) with beneficial effects through their primary action might trigger a paradoxical increase of the frequency and intensity of chest pain after its discontinuation.Drugs used for arterial hypertension (e.g., α-2 agonists, β-blockers, ACE inhibitors, MAO inhibitors, nitrates, sodium nitroprusside, and hydralazine) might produce rebound arterial hypertension after the end of the primary biological effect (half-life).Antiarrhythmic drugs (e.g., adenosine, amiodarone, β-blockers, calcium channel blockers, disopyramide, flecainide, lidocaine, mexiletine, moricizine, and procainamide) may trigger rebound exacerbation of basal ventricular arrhythmias.Antithrombotic drugs (e.g., argatroban, Rev Assoc Med Bras 2022;68(3):303-307 bezafibrate, heparin, salicylates, warfarin, and clopidogrel) might promote thrombotic complications as a result of the rebound effect.Drugs with primary pleiotropic or vasoprotective action (statins) might cause rebound endothelial dysfunction, resulting in predisposition to paradoxical vascular accidents.
Analogously, discontinuation of anxiolytics (e.g., barbiturates, benzodiazepines, and carbamates), sedative-hypnotics (e.g., barbiturates, benzodiazepines, morphine, promethazine, and zopiclone), stimulants of the central nervous system (e.g., amphetamines, caffeine, cocaine, mazindol, and methylphenidate), antidepressants (e.g., tricyclic, MAO inhibitors, and selective serotonin reuptake inhibitors), or antipsychotics (e.g., clozapine, phenothiazines, haloperidol, and pimozide) might cause rebound aggravation of the original condition after the end of their primary therapeutic action.
Anti-inflammatory agents (e.g., steroids, ibuprofen, indomethacin, paracetamol, and salicylates) might trigger a paradoxical increase of inflammation and rebound thrombosis (e.g., ibuprofen, indomethacin, diclofenac, salicylates, rofecoxib, and celecoxib) as a function of their primary platelet anti-aggregation effect.
Analgesics (e.g., caffeine, calcium channels blockers, clonidine, ergotamine, methysergide, opiates, and salicylates) might trigger rebound hyperalgesia.Diuretics (e.g., furosemide, torasemide, and triamterene) might cause sodium and potassium rebound retention, with consequent increase in the plasma volume and the blood pressure.Bronchodilators (e.g., short-and long-acting β-adrenergic agonists, sodium cromoglycate, epinephrine, ipratropium, and nedocromil) might promote rebound bronchoconstriction as a paradoxical reaction to discontinuation.
Anti-dyspeptic (e.g., antacids, H2 antagonists, misoprostol, sucralfate, and proton-pump inhibitors) might trigger rebound increase of hydrochloric acid production and gastrin, with worsening of the original condition.Antiresorptive drugs used for the treatment of osteoporosis (e.g., bisphosphonates, denosumab, and odanacatib) might cause paradoxical atypical fractures due to the rebound increase of osteoclast activity.
Discontinuation of drugs for the treatment of multiple sclerosis (e.g., glucocorticoids, interferon, glatiramer acetate, natalizumab, and fingolimod) might cause rebound increase of the inflammation with exacerbation of clinical symptoms and increase of demyelination lesions.Immunomodulatory agents (e.g., recombinant monoclonal antibodies and tumor necrosis factor inhibitors) indicated for the treatment of psoriasis might trigger rebound psoriasis after discontinuation.The list of examples is much longer [4][5][6][7][8][9][10][11][12][13][14] .
According to these examples, the rebound effect, a universal and automatic physiological mechanism to maintain a constant Rev Assoc Med Bras 2022;68(3):303-307 internal environment or homeostasis, is liable to be elicited by all types of palliative drugs.Due to the high intensity of primary action of drug, such paradoxical reaction might induce severe and eventually fatal adverse events.Exemplifying these iatrogenic events, the long-acting β-adrenergic bronchodilators cause 1 episode of fatal rebound bronchospasm per 1,000 patient-years of use, corresponding to 4,000-5,000 deaths in 2004 in the United States alone, and 40,000-50,000 deaths worldwide 5,7 .Selective serotonin reuptake inhibitor antidepressants cause 5 rebound suicidal manifestations per 1,000 patient-years of use among adolescents, corresponding to 16,500 cases of suicidal ideation or behavior in 2007 in the United States alone 5,8 .Bisphosphonates cause 1-3 episodes of paradoxical atypical fractures per 1,000 patient-years of use 11 .
Principle of Similitude
Assuming that the principle of therapeutic similitude is a "natural law of cure," since 2003, we have been suggesting the homeopathic use of modern drugs employing the rebound effect in a therapeutic way [15][16][17][18][19] , proposing to administer, in ultra-diluted doses, drugs that present, in their primary action, a set of signs and symptoms similar to the manifestations of sick individuals.
The proposal entitled "New Homeopathic Medicines: Use of modern drugs according to the principle of similitude" encompasses 1,250 modern drugs and has been available, since 2021, in three free-access digital books indexed in the Virtual Health Library (i.e., PAHO, WHO, and BIREME) 20 : "Scientific basis of the principle of similitude in modern pharmacology," 21 "Homeopathic materia medica of modern drugs," 22 and "Homeopathic repertory of modern drugs." 23o test the clinical and scientific validity of this proposal, we developed a randomized controlled trial employing potentized estrogen (17-β estradiol) for the treatment of endometriosis-associated pelvic pain 24 , in view of the fact that estrogen causes as an adverse event a set of signs and symptoms similar to the endometriosis syndrome, observing significant improvement compared with placebo in relation to pain, depression, and quality of life 25 .
We hope that these studies will be useful to all homeopathic doctors and researchers in the scientific validation of the therapeutic similitude and enable new applications for the homeopathic treatment.
Figure 1 .
1
Figure 1.Universal mechanism of action of drugs (biphasic action of drugs): primary action of the drug followed by secondary and opposite action of the body (principle of similitude).
Special dossier: "scientific evidence for homeopathy. M Z Teixeira, 10.1590/1806-9282.64.02.93Rev Assoc Med Bras. 6422018
Essay on a new principle for ascertaining the curative power of drugs, with a few glances at those hitherto employed. S Hahnemann, The lesser writings of Samuel Hahnemann. R E Dudgeon, New YorkRadde1852. 2021 Dec 27
Organon of medicine. S Hahnemann, 1991. 2021 Dec 27B Jain PublishersNew Delhitranslated by William Boericke. internet. 6th ed
Similitude in modern pharmacology. M Z Teixeira, 10.1054/homp.1999.0301Br Homeopath J. 8831999
Evidence of the principle of similitude in modern fatal iatrogenic events. M Z Teixeira, 10.1016/j.homp.2006.06.004Homeopathy. 9542006
NSAIDs, myocardial infarction, rebound effect and similitude. Homeopathy. M Z Teixeira, 10.1016/j.homp.2006.11.009200796
Bronchodilators, fatal asthma, rebound effect and similitude. Homeopathy. M Z Teixeira, 10.1016/j.homp.2007.02.001200796
Antidepressants, suicidality and rebound effect: evidence of similitude?. M Z Teixeira, 10.1016/j.homp.2009.02.004Homeopathy. 9822009
Statins withdrawal, vascular complications, rebound effect and similitude. M Z Teixeira, 10.1016/j.homp.2010.01.001Homeopathy. 9942010
Rebound acid hypersecretion after withdrawal of gastric acid suppressing drugs: new evidence of similitude. M Z Teixeira, 10.1016/j.homp.2011.05.003Homeopathy. 10032011
Antiresorptive drugs (bisphosphonates), atypical fractures and rebound effect: new evidence of similitude. M Z Teixeira, 10.1016/j.homp.2012.07.001Homeopathy. 10142012
Immunomodulatory drugs (natalizumab), worsening of multiple sclerosis, rebound effect and similitude. M Z Teixeira, 10.1016/j.homp.2013.05.001Homeopathy. 10232013
Biological therapies (immunomodulatory drugs), worsening of psoriasis and rebound effect: new evidence of similitude. M Z Teixeira, 10.1016/j.homp.2016.09.002Homeopathy. 10542016
Rebound effect of modern drugs: serious adverse event unknown by health professionals. M Z Teixeira, 10.1016/j.ramb.2013.05.003Rev Assoc Med Bras. 5961992. 2013
Homeopathic use of modern medicines: utilisation of the curative rebound effect. M Z Teixeira, 10.1016/s0306-9877(02)00386-9s0306-9877(02)00386-9Med Hypotheses. 6022003
New homeopathic medicines: use of modern drugs according to the principle of similitude. M Z Teixeira, 10.1016/j.homp.2011.01.002Homeopathy. 10042011
New Homeopathic Medicines' database: a project to employ conventional drugs according to the homeopathic method of treatment. M Z Teixeira, 10.1016/j.eujim.2013.01.001Eur J Integr Med. 532013
. Rev Assoc Med Bras. 6832022
Paradoxical pharmacology': therapeutic strategy used by the 'homeopathic pharmacology' for more than two centuries. M Z Teixeira, 10.51910/ijhdr.v13i49.714Int J High Dilution Res. 13482014
Therapeutic use of the rebound effect of modern drugs. M Z Teixeira, 10.1590/1806-9282.63.02.100Rev Assoc Med Bras. 6321992. 2017New homeopathic medicines
New Homeopathic Medicines" proposal: a database made available in three free-access bilingual digital books. M Z Teixeira, 10.1590/1806-9282.20210482Rev Assoc Med Bras. 67101992. 2021
Scientific basis of the principle of similitude in modern pharmacology. M Z Teixeira, 2021. 2021 Dec 272nd ed. São Paulo: Author's edition
Homeopathic materia medica of modern drugs. M Z Teixeira, 2021. 2021 Dec 272nd ed. São Paulo: Author's edition
Homeopathic repertory of modern drugs. M Z Teixeira, 2021. 2021 Dec 272nd ed. São Paulo: Author's edition
Protocol of randomized controlled trial of potentized estrogen in homeopathic treatment of chronic pelvic pain associated with endometriosis. M Z Teixeira, S Podgaec, E C Baracat, 10.1016/j.homp.2016.03.002Homeopathy. 10532016
Potentized estrogen in homeopathic treatment of endometriosis-associated pelvic pain: a 24-week, randomized, double-blind, placebo-controlled study. M Z Teixeira, S Podgaec, E C Baracat, 10.1016/j.ejogrb.2017.01.052Eur J Obstet Gynecol Reprod Biol. 2112017
| [
-0.011836432851850986,
-0.02337886020541191,
0.012119836173951626,
0.029753977432847023,
-0.06059638410806656,
0.10050806403160095,
-0.048447225242853165,
0.17303210496902466,
0.05749532952904701,
0.05302770435810089,
-0.022275125607848167,
0.09502013027667999,
0.05157025158405304,
0.05074... |
Vascular Ehlers-Danlos Syndrome Presenting as a Pulsatile Neck Mass: a Case Report and Review of Literature
MDBharat Maraj
Department of Medicine
San Francisco Medical Center
University of California
San FranciscoCAUSA
MDEmily Harding-Theobald
Department of Medicine
San Francisco Medical Center
University of California
San FranciscoCAUSA
MDFatima Karaki
Department of Medicine
San Francisco Medical Center
University of California
San FranciscoCAUSA
Vascular Ehlers-Danlos Syndrome Presenting as a Pulsatile Neck Mass: a Case Report and Review of Literature
J Gen Intern Med
33710.1007/s11606-018-4445-3CLINICAL PRACTICEvascularEhlers-danlosaneurysm
Ehlers-Danlos syndrome refers to a spectrum of connective tissue disorders typically caused by mutations in genes responsible for the synthesis of collagen. Patients w i t h E h l e r s -D a n l o s s y n d r o m e o f t e n e x h i b i t hyperflexibility of joints, increased skin elasticity, and tissue fragility. Vascular Ehlers-Danlos (vEDS) is a subtype of Ehlers-Danlos syndrome with a predilection to involve blood vessels. As such, it often manifests as vascular aneurysms and vessel rupture leading to hemorrhage. There are few reports describing primary prevention of aneurysms in the setting of undiagnosed, suspected vEDS. We present a case of a 30-year-old woman who presents with a pulsatile neck mass found to have multiple arterial aneurysms on imaging, hyperflexibility, and characteristic facial features consistent with vEDS. As described in this case, management of a suspected connective tissue disorder is a multidisciplinary approach including vascular surgery, medical therapy, and genetic testing to confirm the diagnosis. We review literature regarding the care of patients with vascular Ehlers-Danlos as it might pertain to hospitalized patients.
INTRODUCTION
Ehlers-Danlos syndrome is a heterogeneous group of rare connective tissue disorders that often manifest with increased skin elasticity, joint hypermobility, and tissue fragility. Vascular Ehlers-Danlos syndrome (vEDS) accounts for fewer than 5% of all Ehlers-Danlos cases 1 . It is associated with an autosomal dominant mutation in COL3A1, responsible for the synthesis of type III collagen [2][3][4] . Type III collagen composes connective tissue found within all organs. It provides tensile strength for organs that must resist permanent dilation from fluctuations in pressure. Consequently, vEDS typically presents as rapidly progressive arterial aneurysms, arterial rupture, bowel perforation, and uterine fragility [5][6][7] . Suspicion often arises when incidental findings are identified on routine imaging studies 6 . Definitive diagnosis requires identification of a heterozygous COL3A1 pathogenic genotype. We report the case of a young woman who was diagnosed with a rapidly enlarging arterial pseudoaneurysm, ultimately found to have vEDS, managed with open ligation of her external carotid artery.
CASE PRESENTATION
A 30-year-old woman with a history of bilateral varicose veins was admitted from otolaryngology clinic with a 3-week history of a painful, rapidly growing right neck mass. The patient was previously diagnosed with parotitis at an outside hospital but the neck mass continued to grow despite completion of a two-week course of cephalexin. She denied trauma or injury to her neck, jaw, or face. She denied fevers, chills, weight loss, visual changes, and arthralgias. The patient had a medical history of persistent bilateral varicose veins despite uncomplicated endovenous ablation 1 year prior to admission. She also had a remote history of colonic perforation secondary to a lowspeed motor vehicle accident which required laparotomy and repair. She did note a history of easy bruising throughout her life. She had no family history of bleeding diathesis or connective tissue disease. On admission, her vitals were within normal limits. Her physical exam was significant for a 3-cm diameter pulsatile mass with surrounding edema of the right neck and mandible. There was a violaceous, reticular rash overlying the mass (Fig. 1a). Skin elasticity was normal. Her face had large eyes, a thin nose, thin lips and a small chin. She had bilateral severe varicose veins without lower extremity edema (Fig. 1b). Distal interphalangeal joints and shoulders were hyperextensible with multiple movements (Fig. 1d, e). Metacarpophalangeal joints hyperextended > 90°, hyperflexion of wrists approached 140°, and her knees achieved hyperextension > 15°. Cardiovascular, pulmonary, abdominal, and neurologic examinations were unremarkable. Complete blood count, electrolytes, serum creatinine, liver function tests, and international normalized ratio were within normal limits. Blood cultures were negative. Erythrocyte sedimentation rate and C-reactive protein were not elevated. Antinuclear antibody, rheumatoid factor, anti-neutrophil cytoplasmic antibody, and complement levels were unremarkable.
Computer tomography angiography (CTA) of the neck revealed a 2.7-cm aneurysm arising from the proximal right internal maxillary artery (Fig. 2) as well as a 4-mm aneurysm in the proximal right internal carotid artery. Brain CTA showed a 3-mm aneurysm of the left middle cerebral artery. Chest, abdomen, and pelvis CTA did not reveal any other aneurysms. Transthoracic echocardiography did not show mitral valve prolapse or other abnormalities.
Rheumatology, otolaryngology, interventional radiology, and vascular surgery were consulted. The patient's clinical picture was thought to be most consistent with vEDS. After multidisciplinary discussions, the patient underwent an urgent open ligation of the maxillary and temporal artery via vascular surgery. The surgery was uncomplicated and the patient made a full recovery. Genetic testing was sent to confirm the diagnosis of vEDS. She was started on carvedilol, oral contraception, and was discharged with genetics follow-up and a CTA head and neck planned for 3 months after discharge.
Our patient was diagnosed with the COL3A1 gene mutation, confirming the diagnosis of vEDS. Ongoing screening of vascular lesions was determined on an individual basis by vascular surgery. The interval and modality depends on the location and size of lesions. Genetics was also consulted to discuss the risk of inheritance and pregnancy with the patient and her family.
DISCUSSION
Diagnosis of vEDS is challenging because of variable penetrance within families. A family history of connective tissue disease can be absent as haploinsufficiency and biallelic sequence variants lead to variable clinical presentations and severity of illness 7,8 . De novo mutations in the COL3A1 gene are also a possibility as was suspected in our patient 9 .
There are 5 major and 12 minor criteria that distinguish vEDS from other forms of Ehlers-Danlos and help to establish a clinical diagnosis 10 . Of the major criteria-arterial vasculopathy at < 40 years of age, spontaneous colon or uterine rupture, unexplained carotid-cavernous sinus fistulization, and family history-our patient had bowel perforation despite minimal trauma and early-onset vasculopathy. Several minor criteria were also present including easy bruising, thin skin (indicated by visible veins), characteristic facial features, joint hypermobility, and early-onset varicose veins [10][11][12] . Typical facial features include large eyes, small chin, lobeless ears, and thin nose and lips. However, characteristic facial features are often subtle and can be absent 13 . Joint hypermobility can be assessed by the Beighton score, a standardized evaluation for generalized joint hypermobility 14 . In patients with these features, vEDS should be suspected and genetic testing should be completed to confirm the diagnosis. The diagnosis of vEDS is frequently delayed until after patients present with devastating sequelae. In one study, 61% of patients had at least one severe vascular complication prior to the age of 40 years 15 . Our patient was initially misdiagnosed with parotitis, but she was fortunate to return to care with a visible pulsatile mass that was treated prior to arterial rupture. However, most vascular abnormalities-including arterial aneurysms, dissections, and ectasias-are not visible on physical examination and occur in visceral arteries and deep arteries of the head and neck 16 . As such, practitioners should be aware that many patients first present with hemodynamic instability secondary to emergent internal bleeding. Although our patient was not bleeding, she was at high risk of rupture and urgent treatment of her aneurysm was necessary to prevent a catastrophic bleed.
The management of vascular complications in patients with vEDS is difficult. Endovascular procedures carry a significant risk of arterial dissection and aneurysm formation and are not typically recommended 17 . However, there are case reports of successful endovascular procedures in affected patients 18,19 .
Our patient underwent open ligation of the external carotid artery rather than an endovascular approach in order to avoid arterial rupture and iatrogenic arterial damage. There is little evidence for effective medical management in vEDS. One randomized control trial demonstrated a significant reduction in arterial dissection and rupture with use of celiprolol, a β1-β2 receptor antagonist 20 . Our patient was discharged on carvedilol with the hope that other beta-blockers may offer a similar protective benefit. Oral contraception was warranted to help prevent pregnancy given the risk of uterine rupture. Combined oral contraception was preferred because progestin-only contraceptives have been associated with worsening joint hypermobility 21 .
Vascular Ehlers-Danlos has a relatively poor prognosis. The average life expectancy is 48 to 50 years. Patients typically die from acute arterial rupture leading to exsanguination 22 . Despite treatment, our patient has other aneurysms that pose a significant risk of bleeding and will require close outpatient follow-up. Following vascular lesions with non-invasive imaging has been shown to be an effective tool for counseling patients about the risks and benefits of elective surgical repair. However, patients should also be counseled that close monitoring does not change overall mortality, as fatal lesions are typically rapidly expansive 23 .
CONCLUSION
We describe a case of vEDS in a woman presenting with a pulsatile neck mass. This diagnosis requires a high degree of clinical suspicion and aggressive management to prevent catastrophic consequences. Clinicians should be aware that the vascular subtype can present with findings relatively dissimilar to the classic phenotype of Ehlers-Danlos. Endovascular approaches must be completed with caution and open ligation should be reserved for ruptured vessels or vessels in which rupture is imminent. Wider recognition of this unusual diagnosis will be essential to reducing the high morbidity and mortality associated with vEDS.
Figure 1 .
1a Neck mass with overlying reticular rash. b Prominent varicose veins. c Easily identified veins suggestive of thin skin. d Interphalangeal joint hypermobility of the 1st digit. e Increased range of motion of shoulders.
Figure 2 .
2CTA demonstrating a large pseudoaneurysm of the maxillary artery.
Vascular Ehlers-Danlos syndrome. D P Germain, Y Herrera-Guzman, Ann Genet. 47Germain DP, Herrera-Guzman Y. Vascular Ehlers-Danlos syndrome. Ann Genet 2004;47:1-9.
Heterogeneity of the Ehlers-Danlos syndrome. Description of clinical types and a hypothesis to explain the basic defect. A P Barabas, BMJ. 2Barabas AP. Heterogeneity of the Ehlers-Danlos syndrome. Description of clinical types and a hypothesis to explain the basic defect. BMJ 1967;2:612-3.
Vascular complications in the Ehlers-Danlos syndrome, with especial reference to the Barterial type^or Sack's syndrome. A P Barabas, J Cardiovasc Surg. 13160Barabas AP. Vascular complications in the Ehlers-Danlos syndrome, with especial reference to the Barterial type^or Sack's syndrome. J Cardiovasc Surg 1972;13:160.
Patients with Ehlers-Danlos syndrome type IV lack type III collagen. F M Pope, G R Martin, J R Lichtenstein, Proc Natl Acad Sci. 724Pope FM, Martin GR, Lichtenstein JR, et al. Patients with Ehlers- Danlos syndrome type IV lack type III collagen. Proc Natl Acad Sci 1975;72(4):1314-6.
The spectrum, management and clinical outcome of Ehlers-Danlos syndrome type IV: a 30-year experience. G S Oderich, J M Panneton, T C Bower, J Vasc Surg. 421Oderich GS, Panneton JM, Bower TC, et al. The spectrum, manage- ment and clinical outcome of Ehlers-Danlos syndrome type IV: a 30-year experience. J Vasc Surg. 2005;42(1):98-106.
Vascular-type Ehlers-Danlos syndrome incidentally diagnosed at surgical treatment for hemothorax; report of a case. K Kamiya, A Yoshizu, F Kashizaki, Kyobu Geka. 662Kamiya K, Yoshizu A, Kashizaki F. Vascular-type Ehlers-Danlos syndrome incidentally diagnosed at surgical treatment for hemothorax; report of a case. Kyobu Geka. 2013;66(2):173-5.
COL3A1 haploinsufficiency results in a variety of Ehlers-Danlos syndrome type IV with delayed onset of complications and longer life expectancy. D F Leistritz, M G Pepin, U Schwarze, Genet Med. 138Leistritz DF, Pepin MG, Schwarze U, et al. COL3A1 haploinsufficiency results in a variety of Ehlers-Danlos syndrome type IV with delayed onset of complications and longer life expectancy. Genet Med. 2011;13(8):717-22.
Vascular Ehlers-Danlos Syndrome in siblings with biallelic COL3A1 sequence variants and marked clinical variability in the extended family. A Jørgensen, T Fagerheim, S Rand-Hendriksen, Eur J Hum Genet. 236Jørgensen A, Fagerheim T, Rand-Hendriksen S, et al. Vascular Ehlers- Danlos Syndrome in siblings with biallelic COL3A1 sequence variants and marked clinical variability in the extended family. Eur J Hum Genet. 2015;23(6):796-802.
Ehlers-Danlos Syndrome, Vascular Type. M Pepin, P Byers, Gene Reviews. Initial Posting. Last UpdatePepin M, Byers P. Ehlers-Danlos Syndrome, Vascular Type. Gene Reviews. Initial Posting: September 2, 1999; Last Update: May 3, 2011.
The 2017 international classification of the Ehlers-Danlos syndromes. F Malfait, C Francomano, P Byers, Am J Med Genet Part C Semin Med Genet. 175Malfait F, Francomano C, Byers P, et al. The 2017 international classification of the Ehlers-Danlos syndromes. Am J Med Genet Part C Semin Med Genet. 2017;175C:8-26.
Ehlers-Danlos syndromes: revised nosology, Villefranche, 1997. P Beighton, A De Paepe, B Steinmann, Am J Med Genet. 77Beighton P, De Paepe A, Steinmann B, et al. Ehlers-Danlos syndromes: revised nosology, Villefranche, 1997. Am J Med Genet 1998;77:31-7
Successful segmental thermal ablation of varicose saphenous veins in a patient with confirmed vascular Ehlers-Danlos syndrome. M Frank, J Says, N Denarié, Phlebology. 313Frank M, Says J, Denarié N, et al. Successful segmental thermal ablation of varicose saphenous veins in a patient with confirmed vascular Ehlers-Danlos syndrome. Phlebology. 2016;31(3):222-4.
Vascular Ehlers-Danlos syndrome without the characteristic facial features: a case report. R Inokuchi, H Kurata, K Endo, Medicine (Baltimore). 9328291Inokuchi R, Kurata H, Endo K, et al. Vascular Ehlers-Danlos syndrome without the characteristic facial features: a case report. Medicine (Baltimore). 2014;93(28):e291.
Beighton score: A valid measure for generalized hypermobility in children. B Smits-Engelsman, M Klerks, A Kirby, J Pediatr. 158Smits-Engelsman B, Klerks M, Kirby A. Beighton score: A valid measure for generalized hypermobility in children. J Pediatr. 2011;158:119-123123:e111-114.
The spectrum, management and clinical outcome of Ehlers-Danlos syndrome type IV: a 30-year experience. G S Oderich, J M Panneton, T C Bower, J Vasc Surg. 42Oderich GS, Panneton JM, Bower TC et al. The spectrum, management and clinical outcome of Ehlers-Danlos syndrome type IV: a 30-year experience. J Vasc Surg. 2005;42:98-106.
Vascular Ehlers-Danlos Syndrome: Imaging Findings. M Zilocchi, T Macedo, G Oderich, Am J Rad. 189Zilocchi M, Macedo T, Oderich G, et al. Vascular Ehlers-Danlos Syndrome: Imaging Findings. Am J Rad. 2007;189:712-719.
Treatment of vascular Ehlers-Danlos syndrome: a systematic review. D Bergqvist, M Björck, A Wanhainen, Annals of Surgery. 2582Bergqvist D, Björck M, Wanhainen A. Treatment of vascular Ehlers- Danlos syndrome: a systematic review. Annals of Surgery. 2013;258(2):257-261.
Endovascular repair of direct carotidcavernous fistula in Ehlers-Danlos type IV. I Linfante, E Lin, E Knott, J Neurointerv Surg. 713Linfante I, Lin E, Knott E, et al. Endovascular repair of direct carotid- cavernous fistula in Ehlers-Danlos type IV. J Neurointerv Surg. 2015;7(1):e3.
Successful coil embolization for rupture of the subclavian artery associated with Ehlers-Danlos syndrome type IV. Y Iida, Y Obitsu, H Komai, J Vasc Surg. 505Iida Y, Obitsu Y, Komai H, et al. Successful coil embolization for rupture of the subclavian artery associated with Ehlers-Danlos syndrome type IV. J Vasc Surg. 2009;50(5):1191-5.
Effect of celiprolol on prevention of cardiovascular events in vascular Ehlers-Danlos syndrome: a prospective r a n d o m i s e d. K T Ong, J Perdu, De Backer, J , 376Ong KT, Perdu J, De Backer J, et al. Effect of celiprolol on prevention of cardiovascular events in vascular Ehlers-Danlos syndrome: a prospective r a n d o m i s e d , o p e n , b l i n d e d -e n d p o i n t s t r i a l . L a n c e t . 2010;376(9751):1476-84.
Gynecologic symptoms and the influence on reproductive life in 386 women with hypermobility type ehlers-danlos syndrome: a cohort study. J Hugon-Rodin, G Lebegue, S Becourt, Orphanet J Rare Dis. 111124Hugon-Rodin J, Lebegue G, Becourt S, et al. Gynecologic symptoms and the influence on reproductive life in 386 women with hypermobility type ehlers-danlos syndrome: a cohort study. Orphanet J Rare Dis. 2016;11(1):124.
Sudden and unexpected death in three cases of Ehlers-Danlos syndrome type IV. Lbe Shields, C M Rolf, G J Davis, J Forensic Sciences. 556Shields LBE, Rolf CM, Davis GJ, et al. Sudden and unexpected death in three cases of Ehlers-Danlos syndrome type IV. J Forensic Sciences. 2010;55(6):1641-1645.
Ehlers-Danlos syndrome and Marfan syndrome; Best Practice and Research. B Callewaert, F Malfait, B Loeys, Clinical Rheumatology. 22Callewaert B, Malfait F, Loeys B, et al. Ehlers-Danlos syndrome and Marfan syndrome; Best Practice and Research. Clinical Rheumatology. 2008;22:165-189.
| [
-0.04551784694194794,
0.048707447946071625,
0.003340714378282428,
0.02605278789997101,
0.030826643109321594,
-0.0863664522767067,
-0.14956822991371155,
0.17757436633110046,
0.09224796295166016,
0.04146786034107208,
-0.05913437902927399,
0.026168163865804672,
-0.0004045881796628237,
0.03192... |
5 Sep 2007
E Sauvan sauvan@cppm.in2p3.fr
CPPM
IN2P3-CNRS et Université de la Méditerranée
163 Av. de LuminyF-13288MarseilleFrance
5 Sep 2007Excited Fermions at H1
We present a search for excited neutrinos and electrons using all data collected by the H1 experiment at HERA at a center-of-mass energy of 320 GeV with an integrated luminosity of up to 435 pb −1 . No evidence for excited neutrino or electron production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, f /Λ. These limits greatly extend the excluded region to higher masses than has been possible in previous searches.
Introduction
The existence of three distinct generations of fermions and the hierarchy of their masses motivates the possibility of a new scale of matter yet unobserved. An unambiguous signature for a new scale of matter would be the direct observation of excited states of fermions (f * ), via their decay into a gauge boson and a fermion. Effective models describing the interaction of excited fermions with standard matter have been proposed [1,2,3]. In the models [1,2] the interaction of an f * with a gauge boson is described by a magnetic coupling proportional to 1/Λ where Λ is a new scale. Proportionality constants f , f ′ and f s result in different couplings to U (1), SU (2) and SU (3) gauge bosons. Electron (or positron) and proton collisions at very high energies provide an excellent environment to look for excited states of first generation fermions. In particular, these excited neutrinos (ν * ) and electrons (e * ) could be singly produced through t-channel W or γ/Z boson exchange, respectively.
In this paper we present a search for both excited neutrinos and electrons using all HERA collider data of the H1 experiment. The data collected at electron and proton beam energies of 27.6 GeV and 920 GeV respectively corresponds to an integrated luminosity of up to 435 pb −1 . The excited neutrinos and electrons are searched for through all their electroweak decays into a fermion and a gauge boson (γ, W and Z).
Search for excited neutrinos
In this search, hadronic and leptonic decay channels of the W and Z bosons are considered (see table 1). The analysis covers ∼ 90% of the total branching ratio of ν * decay. The selection criteria of the three main decay channels are described in the following.
In the νγ resonance search, the principal signature is an isolated electromagnetic cluster in events with missing tranverse momentum (P miss T ). Backgrounds arise from charged current (CC) events with an isolated π 0 or initial or final state radiation. The presence of a neutrino is inferred 1 On behalf of the H1 Collaboration by requiring P miss T > 15 GeV. A photon is tagged by identifying an electromagnetic cluster with P γ T > 20 GeV. No well measured track should point to the electromagnetic cluster. Radiative CC events are suppressed by requiring that the four-momentum transfer squared determined from the electromagnetic cluster be log(Q 2 γ ) > 3.5 GeV 2 . Table 1. Observed and predicted event yields for the studied decay channels. The errors on the prediction include model uncertainties and experimental systematic errors added in quadrature.
Selection Data SM Efficiency × BR ν * →νγ 9 15 ± 4 50 % ν * →eW ֒→qq 198 189 ± 33 30-40 % ν * →νZ ֒→qq 111 102 ± 24 40 % ν * →eW ֒→νµ 0 0.54 ± 0.04 3-4.5 % ν * →eW ֒→νe 0 0.6 ± 0.3 4-6 % ν * →νZ ֒→ee 0 0.12 ± 0.04 2 % e * →νW ֒→qq 172 175 ± 39 ∼ 40 % e * →eZ ֒→qq 351 318 ± 64 ∼ 45 % e * →eγ 112 125 ± 19 60-70 %
For the νZ ֒→qq resonance search, the dominant SM background consists of multi-jet CC events with a moderate contribution from photoproduction. The presence of a neutrino is inferred from substantial missing momentum P miss T > 20 GeV. We use a subsample of events with at least two jets, each having a transverse momentum larger than 20 and 15 GeV, respectively, and a polar angle between 5 • and 130 • . At low P miss T , cuts on the variable i E i − P i z , where the sum runs over all visible particles, and on the ratio V ap /V p of transverse energy flow anti-parallel and parallel to the hadronic final state [4] are used to suppress CC and photoproduction events. The Z candidate is reconstructed from the combination of two jets with an invariant mass closest to the nominal Z boson mass. In the eW ֒→qq channel, multi-jet neutral current (NC) events constitute the main contribution from SM processes. Events are selected by the presence of an electron in the LAr with Q 2 e > 2500 GeV 2 or a tranverse momentum P e T greater than 25 GeV. The restriction on the electron polar angle to the forward region of the LAr (5 • < θ e < 90 • ) removes a large part of the NC DIS contribution. The presence of at least two high P T jets with P jet1, jet2 T > 20, 15 GeV and 5 • < θ jet1, jet2 < 130 • is required. A W candidate is then reconstructed in those events from the combinaison of two jets with an invariant mass closest to the nominal W boson mass.
The event yields observed in each decay channel are summarised in table 1. The observed event yields are in good agreement with SM expectations. No deviation is also observed in invariant mass distributions of excited neutrino candidates reconstructed in each decay channel. Since there is no evidence for excited neutrino production, new bounds on the ν * mass as a function of f /Λ have been derived. They are presented in figure 1(a) and (b), under the two conventional assumptions f = −f ′ and f = +f ′ , respectively. Assuming f /Λ = 1/M ν * and f = −f ′ , ν * masses below 211 GeV are ruled out.
This result is presently the most stringent world limit for ν * production and demonstrates the unique HERA sensitivity for ν * masses beyond LEP reach.
Search for excited electrons
In the search for e * , W and Z bosons are reconstructed only in the hadronic decay channel. The total branching ratio accessed is ∼ 80%.
The signature in the eγ channel consists of two isolated, high transverse momentum electromagnetic clusters. The principal SM background arise from elastic and inelastic Compton events. Two isolated electromagnetic clusters in the polar angle 5 • < θ e1,e2 < 130 • are required, with a transverse momentum larger than 20 and 15 GeV, respectively. To further suppress contributions from Compton events, the sum of the energies of the two electromagnetic clusters has to be greater than 100 GeV and the sum of their transverse momentum should be larger than 75 GeV.
The selection criteria used in the νW ֒→qq and eZ ֒→qq channels are similar to those of the νZ ֒→qq and eW ֒→qq channels of the ν * search. The event yields observed in each decay channel are summarised in table 1. They are in good agreement with SM expectations and no deviation is observed in invariant mass distributions of excited neutrino candidates. The new limit on the e * mass as a function of f /Λ is presented in figure 2, using the assumption f = +f ′ . Assuming f /Λ = 1/M e * and f = +f ′ , e * masses below 273 GeV are ruled out.
This result is equivalent to the most recent limit on e * production obtained at the Tevatron by the D0 Collaboration and using 1 fb −1 of data.
Figure 1 .
1Exclusion limits on the coupling f /Λ at 95% C.L. as a function of the mass of the excited neutrino with the assumptions f = −f ′ (a) and f = +f ′ (b), respectively.
Figure 2 .
2Exclusion limits on the coupling f /Λ at 95% C.L. as a function of the mass of the excited electron with the assumption f = +f ′ .
. K Hagiwara, D Zeppenfeld, S Komamiya, Z. Phys. C. 29115Hagiwara K, Zeppenfeld D and Komamiya S (1985) Z. Phys. C 29 115
. F Boudjema, A Djouadi, J L Kneur, Z. Phys. C. 57425Boudjema F, Djouadi A and Kneur J L (1993) Z. Phys. C 57 425
. U Baur, M Spira, P M Zerwas, Phys. Rev. D. 42815Baur U, Spira M and Zerwas P M (1990) Phys. Rev. D 42 815
. C Adloff, H1 Collaborationhep-ex/0304003Eur. Phys. J. C. 301Adloff C et al. [H1 Collaboration] (2003) Eur. Phys. J. C 30 1 (Preprint hep-ex/0304003)
| [
-0.15455549955368042,
-0.08695733547210693,
-0.07890824228525162,
0.16285093128681183,
0.09926751255989075,
-0.05754798650741577,
-0.05369153246283531,
0.09073036909103394,
-0.030900586396455765,
-0.07628951966762543,
-0.0017869477160274982,
-0.02602408453822136,
-0.015723420307040215,
-0.... |
Paroxysmal hypothermia and hyperhidrosis with exacerbation after COVID-19 Infection
2021
Guillaume Lamotte
Department of Neurology
Mayo Clinic
200 1st Street SW55905RochesterMNUSA
Eduardo E Benarroch
Department of Neurology
Mayo Clinic
200 1st Street SW55905RochesterMNUSA
Elizabeth A Coon
Department of Neurology
Mayo Clinic
200 1st Street SW55905RochesterMNUSA
Paroxysmal hypothermia and hyperhidrosis with exacerbation after COVID-19 Infection
Clinical Autonomic Research
32021Received: 23 January 2021 / Accepted: 27 January 2021 / Published online: 2 February 2021LETTER TO THE EDITORShapiro syndrome · COVID-19 · Hypothermia Dear editors,
We present the case of a 49-year-old woman with exacerbation of paroxysmal hyperhidrosis and hypothermia after COVID-19 infection.A 49-year-old woman presented to the autonomic disorder clinic for evaluation of paroxysmal hyperhidrosis and hypothermia. Starting at age 46, she experienced episodes of hyperhidrosis, most pronounced in the face and upper body, followed by profound hypothermia (32-33 °C) associated with confusion and lethargy. Episodes were triggered by minimal intensity physical activity and heat exposure. Each episodes lasted 3-6 h, and they happened on average once per month. Her medical history was significant for hypertension as well as endometriosis and ovarian cyst treated with total abdominal hysterectomy and bilateral salpingooophorectomy. Neurological examination was unremarkable. Laboratory testing including thyroid and adrenal function tests was unremarkable. Magnetic resonance imaging of the brain was unremarkable, with intact corpus callosum. Standardized autonomic testing revealed normal postganglionic sympathetic sudomotor, cardiovagal, and cardiovascular adrenergic functions. A thermoregulatory sweat test (TST) demonstrated lower extremity anhidrosis. The results of the TST and quantitative sudomotor axon reflex test were consistent with preganglionic (central) sudomotor dysfunction(Fig. 1). The patient was diagnosed with Shapiro syndrome variant. She started clonidine extendedrelease 0.1 mg daily by mouth with complete resolution of the symptoms. She was able to resume her daily activities without any limitations.
Six months later she presented with severe fatigue, cough, muscle ache, joint pain, and fever (39.5 °C). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was positive using real-time polymerase chain reaction from a nasopharyngeal swab collection. The patient was diagnosed with mild COVID-19 infection. Outpatient treatment was conservative and symptoms resolved slowly over 3 weeks. During the acute phase of the COVID-19 infection, periods of hypothermia alternated with fever for 4 days. After the recovery phase, however, episodic hyperhidrosis and hypothermia persisted without fever despite the use of clonidine. The patient experienced several episodes of profound hypothermia, all triggered by minimal exertion (e.g., cleaning the house). The dose of clonidine extended-release was increased to 0.1 mg twice daily, which led to complete resolution of the symptoms.
Shapiro syndrome is a rare disorder defined clinically by recurrent hyperhidrosis and hypothermia and radiologically by agenesis of the corpus callosum [1]. The variant form refers to the phenotypic Shapiro syndrome without the corpus callosum abnormality [2]. The pathophysiology of Shapiro syndrome remains poorly understood and may be in part related to hypothalamic dysfunction without structural lesion [1]. Pharmacotherapy with different mechanisms of action may provide symptomatic benefit, suggesting involvement of various neurotransmitters [3].
SARS-CoV-2 is a novel coronavirus responsible for COVID-19. Acute infection has been associated with various neurological manifestations possibly related to endothelial inflammation, cytokine storm, immune reaction, or direct invasion of the central nervous system by the virus [4]. Persistence of symptoms after the acute phase of the infection is not rare; many long-haul COVID patients experience orthostatic intolerance, tachycardia, brain fog, persistent fatigue, and subjective change in body temperature [5].
3
The hypothalamus is part of the central autonomic network and plays a key role in thermoregulation. In Shapiro syndrome, episodic hyperhidrosis is thought to be related to paroxysmal central sympathetic dysregulation, which could explain the benefit of sympatholytic agents such as clonidine [2]. There is evidence that SARS-CoV-2 can lead to hypothalamic dysfunction via direct invasion of the virus and/or reactive inflammation with the olfactory tracts as a port of central nervous system entry [6]. The hypothalamus and associated regions have been shown to express the angiotensin-converting enzyme 2 and transmembrane proteinase, serine 2, which mediate SARS-CoV-2 cellular entry [6]. It can be hypothesized that in the present case, COVID-19 infection, either directly or via cytokine-induced release of prostaglandin E2 from endothelial cells acting via paracrine mechanisms, could have exacerbated dysfunction in the medial preoptic area containing warm-sensitive neurons, triggering excessive sweating and thus hypothermia, exacerbating the preexisting symptoms of variant Shapiro syndrome [7].
Further studies are needed to investigate the possible involvement of the hypothalamus and central autonomic network in COVID-19 infection.
Funding
Supported by NIH (P01NS44233, U54NS065736, K23NS075141, R01 FD004789, R01 NS092625), Cure MSA Foundation, and Mayo Funds.
Fig.
Fig. 1 Thermoregulatory sweat test (TST) and quantitative sudomotor axon reflex test (QSART) in a patient with Shapiro syndrome variant. Absence of sweating on TST in the context of normal QSART responses indicates preganglionic (central) sudomotor dysfunction
Compliance with ethical standardsConflict of interestThe corresponding author affirms that none of the authors has a conflict of interest.
Spontaneous recurrent hypothermia accompanying agenesis of the corpus callosum. W R Shapiro, G H Williams, F Plum, 10.1093/brain/92.2.423Brain. 922Shapiro WR, Williams GH, Plum F (1969) Spontaneous recur- rent hypothermia accompanying agenesis of the corpus callosum. Brain 92(2):423-436. https ://doi.org/10.1093/brain /92.2.423
Shapiro's syndrome: defining the clinical spectrum of the spontaneous paroxysmal hypothermia syndrome. N Tambasco, V Belcastro, P Prontera, P Nigro, E Donti, A Rossi, P Calabresi, 10.1016/j.ejpn.2014.02.001Tambasco N, Belcastro V, Prontera P, Nigro P, Donti E, Rossi A, Calabresi P (2014) Shapiro's syndrome: defining the clinical spectrum of the spontaneous paroxysmal hypothermia syndrome.
. 10.1016/j.ejpn.2014.02.001Eur J Paediatr Neurol. 184Eur J Paediatr Neurol 18(4):453-457. https ://doi.org/10.1016/j. ejpn.2014.02.001
Diagnosis and management of periodic hypothermia. N A Blondin, 10.1212/01.CPJ.0000437350.47610.3aCPJ.00004 37350 .47610 .3aNeurol Clin Pract. 41Blondin NA (2014) Diagnosis and management of periodic hypo- thermia. Neurol Clin Pract 4(1):26-33. https ://doi.org/10.1212/01. CPJ.00004 37350 .47610 .3a
. J Meinhardt, J Radke, C Dittmayer, J Franz, C Thomas, R Mothes, M Laue, J Schneider, S Brünink, S Greuel, M Lehmann, O Hassan, T Aschman, E Schumann, R L Chua, C Conrad, R Eils, W Stenzel, M Windgassen, L Rößler, H H Goebel, H R Gelderblom, H Martin, A Nitsche, W J Schulz-Schaeffer, S Hakroush, M S Winkler, B Tampe, F Scheibe, P Körtvélyessy, D Reinhold, Meinhardt J, Radke J, Dittmayer C, Franz J, Thomas C, Mothes R, Laue M, Schneider J, Brünink S, Greuel S, Lehmann M, Has- san O, Aschman T, Schumann E, Chua RL, Conrad C, Eils R, Stenzel W, Windgassen M, Rößler L, Goebel HH, Gelderblom HR, Martin H, Nitsche A, Schulz-Schaeffer WJ, Hakroush S, Winkler MS, Tampe B, Scheibe F, Körtvélyessy P, Reinhold D,
Olfactory transmucosal SARS-CoV-2 invasion as a port of central nervous system entry in individuals with COVID-19. B Siegmund, A A Kühl, S Elezkurtaj, D Horst, L Oesterhelweg, M Tsokos, B Ingold-Heppner, C Stadelmann, C Drosten, V M Corman, H Radbruch, F L Heppner, 10.1038/s41593-020-00758-5Nat Neurosci. Siegmund B, Kühl AA, Elezkurtaj S, Horst D, Oesterhelweg L, Tsokos M, Ingold-Heppner B, Stadelmann C, Drosten C, Cor- man VM, Radbruch H, Heppner FL (2020) Olfactory transmu- cosal SARS-CoV-2 invasion as a port of central nervous system entry in individuals with COVID-19. Nat Neurosci. https ://doi. org/10.1038/s4159 3-020-00758 -5
Long-Haul COVID. A Nath, 10.1212/wnl.0000000000010640Neurology. 9513Nath A (2020) Long-Haul COVID. Neurology 95(13):559-560. https ://doi.org/10.1212/wnl.00000 00000 01064 0
The hypothalamus as a hub for SARS-CoV-2 brain infection and pathogenesis. S Nampoothiri, F Sauve, G Ternier, D Fernandois, C Coelho, M Imbernon, E Deligia, R Perbet, V Florent, M Baroncini, F Pasquier, F Trottein, C-A Maurage, V Mattot, P Giacobini, S Rasika, V Prevot, 10.1101/2020.06.08.139329Nampoothiri S, Sauve F, Ternier G, Fernandois D, Coe- lho C, Imbernon M, Deligia E, Perbet R, Florent V, Baroncini M, Pasquier F, Trottein F, Maurage C-A, Mat- tot V, Giacobini P, Rasika S, Prevot V (2020) The hypo- thalamus as a hub for SARS-CoV-2 brain infection and pathogenesis. bioRxiv:2020.2006.2008.139329. https ://doi. org/10.1101/2020.06.08.13932 9
Neural circuitry engaged by prostaglandins during the sickness syndrome. C B Saper, A A Romanovsky, T E Scammell, 10.1038/nn.3159Nat Neurosci. 158Saper CB, Romanovsky AA, Scammell TE (2012) Neural cir- cuitry engaged by prostaglandins during the sickness syndrome. Nat Neurosci 15(8):1088-1095. https ://doi.org/10.1038/nn.3159
| [
-0.13392332196235657,
-0.07253724336624146,
0.04194067418575287,
0.14069296419620514,
-0.03150686249136925,
-0.02369648404419422,
-0.08871728926897049,
0.14416278898715973,
-0.0750497579574585,
0.03309335559606552,
0.09698312729597092,
-0.14942675828933716,
0.09170308709144592,
0.111066803... |
Role of Demographic Factors on Emotional Intelligence of Tribhuvan University's Faculty Members
2022
Indira Shrestha piyaindira@yahoo.com
Commerce Campus
Tribhuvan University
LecturerNepal
Role of Demographic Factors on Emotional Intelligence of Tribhuvan University's Faculty Members
Pravaha
2812022
The main objective of this study is to examine the role of demographic factors (age, marital status, education, service year, designation, and income)in the level of emotional intelligence of faculty members. The population of the study is faculty members of the central campus of Tribhuvan Univesity and its constituent campuses situated in Kathmandu, Bhaktapur, and Lalitpur districts. The structured questionnaire was distributed to the one hundred and six faculty members to get information regarding the influence of demographic factors on emotional intelligence. The questions related to emotional intelligence were based on the Goleman model (1998). The analytical research design was used by applying statistical tests like frequency, percentage, and one-way ANOVA for analyzing the data. The result revealed that demographic factors like age, education, service year, designation, and income influence emotional intelligence while marital status and gender do not. Some limitations and scope for future research have been discussed.
Introduction
An individual's emotional intelligencehas become more important in today's business world irrespective of the type of organization.Since the importance of emotions in human life came to light, the idea of emotional intelligence has gained popularity. Emotional intelligence is assessing one's and other's emotions, and controlling and expressing them (Wong & Law, 2002). Lilavati and Chalam (2018)mention that understanding one's own and other people's emotions and responding appropriately are topics of emotional intelligence. Emotional intelligence is believed to affect an employee's personality, work performance, workplace harmony, and happiness. Employees with high emotional intelligence are regarded as upbeat, unattached to the past, maintaining peace at work, and having positive relationships with coworkers. Positive personnel improve productivity, foster positive client relationships, and foster positive attitudes toward the business. Pradhan, Jena, and Sing (2017) state that emotional intelligence and self-efficacy are positively correlated, and self-efficacy is a crucial component of psychological capital. Due to organizations' ongoing search for strategies to help their human capital function consistently, the topic of emotional intelligence is crucial. Emotions and feelings play a vital role in the performance of employees in organizations. The growth of business does not only depend on the intelligence quotient but the emotional intelligence of human resources has a great impact on organizational performance.
Determinants of emotional intelligence
The five elements of the Goleman model (1998), which emphasizes emotional intelligence as a broad range of competencies and skills that influence leadership effectiveness, are as follows:
Self-awareness-knowing one's emotions, strengths, limitations, desires, values, and aspirations while using intuition to inform judgments demonstrates self-awareness. Managing emotions-is controlling or rerouting one's irrational feelings and urges while also adjusting to the situation as it evolves. Social skill-managing other people's emotions to influence them in the way you want. Empathy-recognize, comprehend, and take into account the feelings of others, especially when making decisions. Motivating oneself-encourage yourself to succeed for your own reasons.
Problems and Objectives
The demographic makeup of the academic workforce is changing more quickly than ever before. Despite these modifications, academics are anticipated to give their best performance. With the increasing diversity of values, priorities, and cultures, demographic changes may have an impact on emotional intelligence as a predictor of individual performance (Shukla, & Srivastava, 2016).There may be disparities in employees' beliefs, values, and attitudes due to the workforce's demographic composition (Pooja & Kumar, 2016). The main goal of this study is to examine the influence of demographic factors (gender, marital status, designation, service year, education, age, and income) on emotional intelligence among faculty members of the central campus of T.U. and its constituent campus.
Literature review
According to Goleman (1998), emotional intelligence is the ability to recognize our feelings and those of others, inspire ourselves, and manage emotions in ourselves and our relationships. Salovey and Mayer (1990) described emotional intelligence as one's ability to recognize one's own feelings and others' feelings to get information and use this information for guiding one's actions and emotions. Oztimurlenk (2019) says that the prosperity of an organization depends on the level of emotional intelligence of employees who are working at lower levels as well in the top level of organizations. Samuel and Osman (2022) mention that due to its influence on behavior and interactions with those around one, emotional intelligence is seen as a crucial component. In order to relieve stress, communicate, and connect with others, it is necessary to be able to recognize, use, and understand emotions. Adeyemo (2008) studied the relationship between demographic factors and emotional intelligence among two hundred and fifteen workers of selected organizations using the simple random sampling method. The result showed that work experience, age, and gender seemed to have a significant relationship with their level of emotional intelligence. Gowdhaman and Murugan (2009) analyzed the effect of demographic factors on emotional intelligence among B. Ed teacher trainees. Their result showed that age has a significant relationship with emotional intelligence. Shukla and Srivastava (2016) analyzed the relationship between emotional intelligence and demographic factors and their result showed that age, service year annual income, and education influence the level of emotional intelligence among retail employees. Lilavati and Chalam (2018) analyzed the effect of demographic factors on emotional intelligence among one hundred and forty employees working in retail stores in Vijayawada, Andhra Pradesh. The result of their study revealed that gender, age, and education influence emotional intelligence. Stami, Ritin, and Dominique (2018) studied the effect of demographic factors on emotional intelligence among radiation therapists and found that age, job level, gender, and education of radiation therapists working in cancer care centers in Australia were found to be more significant determinantsof emotional intelligence. Marembo and Chinyamurindi (2018)analyzed the effect of demographic variables on emotional intelligence among early career academics and their result showed that age gender and work experience do not have any influence on emotional intelligence among early career academics in South African higher education institutions. Ozotimurlenk (2019) analyzed the impact of demographic factors on the emotional intelligence of one hundred and forty human resource managers in Turkey. Their result showed that age is the determinant factor affecting the level of emotional intelligence of human resource managers. Uslu (2020) analyzed the association between demographic factors and emotional intelligence and the result showed that the gender of respondents has a significant relationship with emotional intelligence but not with other demographic factors (age, marital status, income, and education. Tetteh, Nsiah, and Ameyah (2021) studied the influence of demographic factors on the emotional intelligence of 140 respondents in Ghana using the convenience sampling method and their results showed that age and marital status are significant factors influencingsub-scales of emotional intelligence amongthe staff of Ghana's private and public institutions. Samuel and Osman (2022) examined the effect of demographic factors on emotional intelligence among five hundred and thirty-six service sector employees and their results revealed that gender does not affect emotional intelligence but age, educational level, and job sector have moderate roles to influence emotional intelligence.
Conceptual framework
The following conceptual framework has been developed based on the literature of (Goleman, 1998;Shukla, & Srivastava 2016;Uslu, 2020). This study has conceptualized moderating variables' (demographic factors) role in emotional intelligence. The moderating variables in this study are as follows: Gender, marital status, designation, service year, education, age, and income
Hypothesis formulation
The following alternative hypotheses have been developed on the basis of a conceptual framework. H 1 : there is a significant influence of gender on the emotional intelligence of university faculty member H 2 : there is a significant influence of marital status on the emotional intelligence of university faculty member H 3 : there is a significant influence of designation on the emotional intelligence of university faculty member H 4 : there is a significant influence of service year on the emotional intelligence of university faculty member H 5 : there is a significant influence of education on the emotional intelligence of university faculty member H 6 : there is a significant influence of age on the emotional intelligence of university faculty member H 7 : there is a significant influence of income on the emotional intelligence of university faculty member
Research Methodology
Respondents were given standardized questionnaires in order to collect data for this study (relating to emotional intelligence). Also, an analytical research design was used in this study to examine how demographic factors affect emotional intelligence (a dependent variable).This study is based on firsthand information gathered from faculty members at the central department of management at TU and its constitute campuses through thoughtfully constructed structured questionnaires.The management faculties at TU's main campus and its affiliated campuses in the Kathmandu, Bhaktapur, and Lalitpur districts made up the study's population. The study's sample size is one hundred and six. The sample was chosen randomly from the central campus and its constituent campus, TU. The emotional intelligence questionnaire is based on Daniel Goleman's idea (1998). A 25-item questionnaire designed to test emotional intelligence has been used to assess its five components: self-awareness (SA), managing emotion (ME), motivating oneself (MO), empathy (E), and social competence (SS).The question was measured on a Likert scale ranging from strongly disagree (1) to strongly agree (5).
Result and Analysis
This section presents the result obtained from data regarding the demographic profile of the respondents and the influences of demographic factors on the level of emotional intelligence. By designation, the study found that lecturers made up the biggest number, at 69.8 percent, compared to readers (22.6 percent), teaching assistants (3.8 percent), and professors (3.8 percent). Considering the respondents' years of service on campus, the majority of respondents (40.6 percent) were >10≤ 15 years, followed by >15≤ 20 years (29.2 percent), >5≤ 10 years (16.0 percent), ≤ 5 years (9.4 percent), and >20 years (4.7 percent).
According to the study, the biggest percentage of respondents (53.8 percent) had an M. Phil., followed by a Master's degree (20.8 percent) and a Ph.D. (25.4 percent).
Considering the respondents' age range, the survey revealed that the majority of respondents were between the ages of >40≤ 45 at 36.8 percent, >35≤ 40 at 29.2 percent, >45≤ 50 at 23.6 percent, >30≤ 35 at 3.8 percent, and over 50 with 6.6 percent. Regarding the total monthly stipend, including the basic and additional amounts, 63.2 percent of respondents had an income of less than or equal to Rs50,000, while 36.8 percent had an income between Rs 50,000 and Rs70,00,000. Regarding the marital status of respondents, no significant difference (t = 1.44 and p-value = 0.255) in the mean value of married and unmarried respondents' emotional intelligence at 0.05 level of significance.
The result revealed in this study rejected the alternative hypothesis H 2 showing evidence of no influence of marital status on emotional intelligence. This is in line with (Uslu,2020) while contrary to (Tetteh, Nsiah, &, Ameyah2021). There is a significant difference (F = 9.206 and p-value = 0.000 between respondents with respect to designation at a 0.05 level of significance accepting the alternative hypothesis H 3 set for the study. This result is in line with (Stami, Ritin, & Dominique 2018).
Regarding service year, there is a significant difference (F = 12.157 and p-value = 0.000) between respondents' level of emotional intelligence at a 0.05 level of significance accepting the alternative hypothesis H 4 . This result is consistent with (Shukla &Srivastava, 2016) while contrary to (Marembo&Chinyamurindi, 2018) showed that service year does not affect emotional intelligence.
Regarding education, there is a significant difference (F = 9.805 and p-value = 0.000) in the emotional intelligence of respondents at a 0.05 level of significance accepting the alternative hypothesis H 5 . This result is consistent with (Lilavati&Chalam, 2018;Stami, Ritin, & Dominique, 2018). Their result revealed that education does not play any role in emotional intelligence.
Regarding age, there is a significant difference (F = 3.816, and p-value = 0.006) in the level of emotional intelligence at a 0.05 level of significance and accepted alternative hypothesis H 6 . This result is consistent with (Shukla & Srivastava, 2016;Lilavati&Chalam, 2018;Stami, Ritin, & Dominique, 2018) but contrary to (Uslu, 2020) showing that age does not affect emotional intelligence. Regarding income, there is a significant difference (F = 23.004, and p-value = 0.000) in emotional intelligenceat a 0.05 level of significance accepting the alternative hypothesis H 7 . This result is consistent with (Shukla & Srivastava, 2016 and inconsistent with (Uslu, 2020) revealed that income does not affect emotional intelligence.
Conclusion
The study's findings revealed that demographic factors influence the level of emotional intelligence of Tribhuvan University faculty members. Some demographic characteristics were found to have a significant influence on their emotional intelligence. Gender and marital status of faculty members did not appear to play any effect in influencing emotional intelligence, however, some demographic parameters such as the level of education, service year, age, and position held by them may affect emotional intelligence. According to research, these factors will also impact their ability to maintain emotional stability. An increase in age, experience, education level, and position in an organization helps people become more emotionally stable.
To flourish in interpersonal relationships and attain outstanding performance in the workplace, an individual must have emotional intelligence. Organizational training is required to promote emotional intelligence and reduce the effect of demographic factors on emotional intelligence. A socializing program for new hires should be provided, according to Adeyemo (2008), in order to make up for their lack of experience. This study has some limitations and does not cover all the faculty members of other universities in Nepal so future researchers are suggested to conduct research in other sectors like a hospital, hotel industries, and tourism sectors because the emotional intelligence of the workforce plays a vital role in those sectors.
Table 1
1Demographic status of respondentsPersonality
Respondent
Percentage (%)
Gender
Male
104
98.1
Female
2
1.9
Total
106
100
Marital Status
Married
105
99.1
Unmarried
1
0.9
Divorced
0
0
Widow
0
0
Total
106
100
Designation
Teaching Assistant
4
3.8
Lecturer
74
69.8
Reader
24
22.6
Professor
4
3.8
Total
106
100
Service Year
≤ 5
10
9.4
>5≤ 10
17
16.0
>10≤ 15
43
40.6
>15≤ 20
31
29.2
Above 20
5
4.7
Total
106
100
Education
Masters
22
20.8
M. Phil
57
53.8
PhD
27
25.4
Post-Doctorate
0
0
Total
106
100
Table 2
2Demographic Status and Level of Emotional IntelligenceVariables
Demographic and emotional intelligence among workers in some selected organizations in Oyo state. D A Adeyemo, Nigeria. The Journal of Business Perspective. 121Adeyemo, D. A. (2008). Demographic and emotional intelligence among workers in some selected organizations in Oyo state, Nigeria. The Journal of Business Perspective, 12(1), 43-48.
Working with emotional intelligence. D Goleman, NY: BantamGoleman, D. (1998). Working with emotional intelligence. NY: Bantam.
Emotional intelligence among B.Ed teacher trainees. K Gowdhaman, G M &murugan, Psycho-Lingua. 392Gowdhaman, K. &Murugan, G. M. (2009). Emotional intelligence among B.Ed teacher trainees. Psycho- Lingua, 39(2), 187-190.
Impact of demographic factors on emotional intelligence. An empirical analysis. T S Lilavati, G V &chalam, Journal of Emerging Technologies and Innovative Research. 66Lilavati, T. S. &Chalam, G. V. (2019). Impact of demographic factors on emotional intelligence. An empirical analysis. Journal of Emerging Technologies and Innovative Research, 6(6), 136-144.
Impact of demographic variables on emotional intelligence levels amongst a sample of early career academics at South African higher education institutions. M Marembo, W T &chinyamurindi, SA South Asian Journal of Human Resource Management. 160Marembo, M. &Chinyamurindi, W. T. (2018). Impact of demographic variables on emotional intelligence levels amongst a sample of early career academics at South African higher education institutions. SA South Asian Journal of Human Resource Management,16(0), 1-9.
Demographic factors affecting emotional intelligence levels. A study on human resources managers in Turkey. S Oztimurlenk, Journal of Global Business and Technology. 161Oztimurlenk, S. (2019). Demographic factors affecting emotional intelligence levels. A study on human resources managers in Turkey. Journal of Global Business and Technology, 16(1), 80-90.
Demographic variables and its effect on emotional intelligence: a study on Indian service sector employees. P Pooja, P Kumar, Annals of Neurosciences. 231Pooja, P., & Kumar, P. (2016). Demographic variables and its effect on emotional intelligence: a study on Indian service sector employees. Annals of Neurosciences, 23(1), 18-24.
Examining the role of intelligence between organizational learning and adaptive performance in Indian manufacturing industries. R K Pradhan, L K Jena, S K &sing, Journal of Workplace Learning. 293Pradhan, R. K., Jena, L. K. &Sing, S. K. (2017). Examining the role of intelligence between organizational learning and adaptive performance in Indian manufacturing industries. Journal of Workplace Learning, 29(3), 235-247.
Emotional intelligence. Imagination, Cognition, and Personality. P Salovey, J D Mayer, 9Salovey, P. & Mayer, J. D. (1990). Emotional intelligence. Imagination, Cognition, and Personality, 9, 185-211.
Emotional Intelligence and demographic characteristics of service sector employees. R Samuel, I Osman, International Journal of Research in Business and Social Sciences. 128Samuel, R. & Osman, I. (2022). Emotional Intelligence and demographic characteristics of service sector employees. International Journal of Research in Business and Social Sciences, 12(8), 430-443.
Examining the effect of emotional intelligence on socio-demographic variables and job stress among retail employees. A Shukla, R &srivastava, Cogent Business &Management. 31Shukla, A. &Srivastava, R. (2016). Examining the effect of emotional intelligence on socio-demographic variables and job stress among retail employees. Cogent Business &Management, 3(1), 1-18.
Demographic predictors of emotional intelligence among radiation therapists. T Stami, F Ritin, P Dominique, Journal of Medical Radiation Sciences. 652Stami, T, Ritin, F. & Dominique, P. (2018). Demographic predictors of emotional intelligence among radiation therapists. Journal of Medical Radiation Sciences, 65(2), 114-122.
A study into the effect of demographics on emotional intelligence in Ghana. R Tetteh, T B Nsiah, J D &ameyah, Journal of Research in Business and Management. 910Tetteh, R., Nsiah, T. B. &Ameyah, J. D. (2021). A study into the effect of demographics on emotional intelligence in Ghana. Journal of Research in Business and Management, 9(10), 43-55.
How demographic factors associated with employees' emotional intelligence. O Uslu, Journal of Faculty of Economics and administrative science. 1121Uslu, O. (2020). How demographic factors associated with employees' emotional intelligence? Journal of Faculty of Economics and administrative science, 11(21), 88-100.
The effects of leader and follower emotional intelligence on performance and attitude. An explanatory study. C S Wong, K S Law, Leadership Quarterly. 132Wong, C. S., & Law, K. S. (2002). The effects of leader and follower emotional intelligence on performance and attitude. An explanatory study. Leadership Quarterly, 13(2), 243-274.
| [
0.07053554058074951,
0.014124476350843906,
-0.06843821704387665,
0.12326564639806747,
-0.08556555211544037,
0.022598261013627052,
0.04135599732398987,
-0.08060461282730103,
0.07402697205543518,
0.03450331836938858,
0.2169322371482849,
-0.05496616289019585,
0.040357839316129684,
-0.15935255... |
Intensity interferometry with more than two detectors?
May 2014
Vinay Malvimat
School of Physics
University of Hyderabad
GachibowliHyderabad-500046India
Olaf Wucknitz
Max-Planck-Institut für Radioastronomie
Auf dem Hügel 6953121BonnGermany
Argelander-Institut für Astronomie
Auf dem Hügel 7153121BonnGermany
Prasenjit Saha
Institute for Theoretical Physics
University of Zurich
Winterthurerstr 1908057ZurichSwitzerland
Intensity interferometry with more than two detectors?
Mon. Not. R. Astron. Soc
0000000May 2014Accepted 2013 October 8. Received 2013 September 10; in original form 2013 April 11Printed 11 (MN L A T E X style file v2.2)instrumentation: interferometers
The original intensity interferometers were instruments built in the 1950s and 60s by Hanbury Brown and collaborators, achieving milli-arcsec resolutions in visible light without optical-quality mirrors. They exploited a then-novel physical effect, nowadays known as HBT correlation after the experiments of Hanbury Brown and Twiss, and considered fundamental in quantum optics. Now a new generation of intensity interferometers is being designed, raising the possibility of measuring intensity correlations with three or more detectors.Quantum-optics predicts two interesting features in many-detector HBT: (i) the signal contains spatial information about the source (such as the bispectrum or closure phase) not present in standard HBT, and (ii) correlation increases combinatorially with the number of detectors. The signal to noise ratio (SNR) depends crucially on the number of photons -in practice always 1 -detected per coherence time. A simple SNR formula is derived for thermal sources, indicating that three-detector HBT is feasible for bright stars. The many-detector enhancement of HBT would be much more difficult to measure, but seems plausible for bright masers.1 The semi-classical description is not valid in general. A nice counter-example is provided by electrons, which show HBT anti-correlation (Kiesel et al. 2002) from fermion statistics. c 0000 RAS
INTRODUCTION
If two detectors are counting photons from an ordinary incoherent light source, there is a tendency for photons to arrive at both detectors together. This is known as photon bunching or HBT correlation, after the pioneering work of Hanbury Brown and Twiss, and is a consequence of the bosonic quantum statistics of photons. In a situation where coherent light would produce interference fringes, the HBT correlation with incoherent light varies according to those would-be but absent fringe patterns. This allows a type of interferometry with incoherent light and without optical-quality mirrors, known as intensity interferometry.
HBT correlation appears naturally in classical wave optics, and was actually first used to build a radio intensity interferometer, which resolved an extra-galactic radio source for the first time (Hanbury Brown et al. 1952). But when the same ideas were applied to visible light, and the effect was measured, first in the lab (Hanbury Brown & Twiss 1956) and then with starlight (Hanbury Brown & Twiss 1958), it became controversial, because it implied that different photons could interfere, contrary to conventional wisdom at the time. The controversies were eventually resolved with the development of a quantum-statistical theory for incoherent light by Sudarshan (1963) and Glauber (1963) and the emergence of quantum optics. In quantum optics, ordinary light (or 'chaotic light') behaves like a random mixture of lasers, and the semi-classical picture of interfering waves, the squared amplitudes of which determine the emission rate of photo-electrons, turns out to be valid. 1 The general phenomenon of photon bunching or HBT correlation then spread to different areas of physics in different guises. For example, it is well known in the context of nuclear collisions (Baym 1998), and it may even be relevant to animal vision (Sim et al. 2012).
Meanwhile, Hanbury Brown and collaborators developed the Narrabri Stellar Intensity Interferometer (NSII) which measured stellar diameters down to milli-arcsecs (Hanbury Brown 1968). But the photon detectors then available were only blue-sensitive, limiting the instrument to hot stars. So the NSII ran out of stars to observe in a few years, after which it was dismantled and almost forgotten. Decades later, with a new generation of detectors, intensity interferometry has become somewhat topical in astronomy again. A number of proposals and experiments have appeared in recent years (Ofir & Ribak 2006a,b;Borra 2008;Jain & Ralston 2008;Foellmi 2009;Horch & Camarata 2012). Particularly ambitious are plans to adapt Cherenkov telescopes into a giant reincarnated NSII with resolution down to < 0.03 mas Dravins et al. 2012).
Future intensity interferometers are likely to have many detectors, not just two. Clearly, detectors can work in simultaneous pairs. The prospect of measuring N -fold photon coincidences has also been suggested (e.g., Ofir & Ribak 2006a). The basic theory is well established in the quantum-optics literature and three-detector HBT has been measured in laboratory experiments (Sato et al. 1978;Zhou et al. 2010). But are the results interesting for an astronomical instrument? This paper examines the question.
STANDARD HBT
A nice introduction to HBT from a modern quantum-optics perspective appears in Glauber (2006). We quote some key results here.
The central concept is the field correlation functions. Let x1 and x2 denote the spacetime locations of two detectors. The first-order correlation 2 is defined as the average
G(x1, x2) ≡ E (−) (x1) E (+) (x2) .
(1)
Classically, E (±) denote the positive and negative frequency parts of the electric field at a detector. In quantum statistics, the fields become operators. We recognize G(x1, x2) as the unnormalized correlation function or 'visibility' in radio interferometry, or the spatial Fourier transform of the source in the sky. Note that G(x2, x1) is the complex conjugate (Hermitian conjugate in quantum statistics) of G(x1, x2). Thus G(x1, x1), which is the count rate at x1, is automatically real and non-negative. For a laser source, G(x1, x2) would be independent of time, but for chaotic sources, the correlation falls away over a coherence time ∆τ ≈ 1/∆ν .
Now consider a form of second-order correlation
G (2) (x1, x2, x2, x1) ≡ E (−) (x1) E (−) (x2) E (+) (x2) E (+) (x1)(3)
which is the probability of coincident detection within ∆τ . Chaotic sources have the property (cf. Glauber's equation 37)
G (2) (x1, x2, x2, x1) = G(x1, x1) G(x2, x2) + |G(x1, x2)| 2 .(4)
The first term corresponds to the random coincidences that would also be expected for classical particles, but the second term describes the non-classical HBT correlations.
To estimate the signal to noise, suppose we have two detectors with equal count rates r (photons per time unit), parametrized as
r ∆τ = G(x1, x1) = G(x2, x2) ,(5)
so that G(x, x) provides the number of photons per coherence time. Let us now count photons over some time ∆t. The time resolution ∆t of the detector, typically ∆t ∆τ , is often called the reciprocal electrical bandwidth, because in the early experiments it was set by amplifier properties.
The product of photon counts (corresponding to random coincidences) will be close to (r∆t) 2 , as given by the first term on the right of equation (4). The HBT signal given by the second term will make a small but non-zero contribution. Over a coherence time it will be |G(x1, x2)| 2 . Over the much longer interval ∆t there are, so to speak, ∆t/∆τ coherent slices, making the HBT signal r 2 ∆τ ∆t. Using Poisson noise for the photon numbers and thus interpreting the square root of the total coincidence rate as the noise, we get a signal to noise ratio SNR(∆t) ∼ r ∆τ
for full correlation. This applies to a single counting time ∆t. Over many counting times, the SNR adds in quadrature so that we get 3 SNR(T ) ∼ r ∆τ T ∆t (7) when integrating over a duration T .When increasing the coherence time by using narrow-band filters, the photon rate r will decrease with ∆ν ≈ 1/∆τ so that the 'spectral intensity' r∆τ stays constant. This has the remarkable effect that adding narrow-band filters does not reduce the achieved SNR. This makes it possible to increase the SNR further by using spectral detectors that can distinguish between different photon energies (within the limits of the uncertainty principle) and effectively record many narrow channels simultaneously. Or one can decrease the optical bandwidth so much that photon count rates are sufficiently low not to be affected by detector dead times.
In the NSII, the counting time ∆t was ∼ 10 nanosec. Current off-the-shelf instruments can achieve ∆t 50 picosec (not to mention better quantum efficiency and broader wavelength response). Clearly the time resolution is very good, but it is still orders of magnitude longer than the coherence time. Both these inequalities are important. The first inequality, or ∆t ∆τ , is what makes intensity interferometry interesting in the first place. In standard interferometry, optical paths have to be kept under control to better than λ, which is extremely demanding mechanically. For intensity interferometry, path differences do not matter as long as they are well below c∆t, corresponding to metres in the first experiments. This not only relaxes the mechanical tolerances, it makes the signal immune to atmospheric fluctuations. Compared to other techniques, intensity interferometry is possible with simpler technology. Put in another way, if we lack the precision to measure the first-order correlation G(x1, x2) directly, we can still get information on it indirectly through the second-order correlation. The second inequality, or ∆t
T , is what makes intensity interferometry usable with very low coincidence rates. The NSII could operate at r ∆τ ∼ 10 −5 , because it had 10 8 counting times per second and hence could build up SNR ∼ 10 4 r ∆τ in a second. Current technology could deliver at least another order of magnitude better.
The above description, in terms of counting photons, is well suited to optical astronomy. In radio astronomy, on the other hand, a description in terms of waves and intensities is standard. For incoherent sources, the E (±) fields are considered as (complex) Gaussian random variables with autocorrelation functions determined by the characteristics of the receiving system. Each measurement naturally consists of a finite sum of random amplitudes, so that the fields and intensities vary with time even for sources of constant luminosity. This 'wave noise' or 'self noise' defines the fluctuations whose correlations are measured as the HBT effect. The wave noise also adds to the photon shot noise that is important in the optical domain of low photon rates, and this contribution actually dominates for high r∆τ . We will return to this 'Super-Poisson noise' (see e.g., Labeyrie et al. 2006) later.
Although the semi-classical picture is equivalent to the quantum-optics picture on intensities versus photon counts (Sudarshan 1963), a conceptual difficulty arises when we consider the fields themselves. In standard radio interferometry (not HBT) the electric field is considered as a classical field which can be measured directly. But in quantum optics the electric field is a non-Hermitian operator and hence not itself an observable. How to reconcile the radio-astronomy and quantum-optics pictures? One possible resolution is given in Burke (1969). Here we suggest another, which goes as follows. Let there be a source field S (±) , and let us superpose it on a known local field L (±) . The resulting field
E (±) (x1) = S (±) + L (±)(8)
then gets its intensity measured:
G(x1, x1) = S (−) S (+) + L (−) L (+) + S (−) L (+) + L (−) S (+) .(9)
Here the first two terms on the right are just the intensities |S| 2 and |L| 2 of the two fields. The last two terms give a beating oscillation in the photon count rates, and it is from these oscillations that the phase S (±) is inferred. Thus, even if the source field cannot be measured directly, it can be inferred indirectly. To estimate the SNR, we note that the signal is in the last two terms of (9), and the noise will be mainly the noise in the second term. Thus,
SNR (G(x1, x1)) |S| |L| / noise L (−) L (+) .(10)
If the local field is coherent, the denominator will follow Poisson noise and hence be ∝ |L|, making the SNR ∝ |S|, just as expected from the photon-counting picture. If the local field is not coherent, it will be subject to its own HBT fluctuations, or wave noise. We suggest the latter as a possible interpretation of the well-known 'receiver noise', which is the dominant noise in radio astronomy.
MORE THAN TWO DETECTORS
For chaotic sources, the higher order correlation functions are all given in terms of the first-order correlations. The result is presented in equation (10.27) of Glauber (1963), which, with a slight modification of notation, reads
G (n) (x1, . . . , xN , xN , . . . , x1) = P N k=1 G(x k , Px k ) .(11)
Here Px k denotes the k th element of a permutation of {x1, . . . , xN }. The sum is over all permutations. In each term, the first argument always runs as x1, x2, . . . whereas the second argument runs as a permutation of that ordering. As we remarked earlier, in quantum optics, the G are correlations between the field operators, but the semi-classical approach of treating the fields as classical and then interpreting intensities as photon probabilities is valid for light (cf. Sudarshan 1963). Indeed, equation (11) also appears in the classical theory of random Gaussian variables, where it is known as Isserlis' theorem. For three detectors, the formula (11) gives
G (3) (x1, x2, x3, x3, x2, x1) = G(x1, x1) G(x2, x2) G(x3, x3) + G(x1, x3) G(x2, x2) G(x3, x1) + G(x1, x2) G(x2, x3) G(x3, x1) + G(x1, x1) G(x2, x3) G(x3, x2) + G(x1, x3) G(x2, x1) G(x3, x2) + G(x1, x2) G(x2, x1) G(x3, x3) .(12)
In each term here, the first argument always runs as x1, x2, x3 whereas the second argument runs as a permutation of that ordering. One can rewrite this expression in another way, which is easier to interpret, by introducing the normalized correlations
g12 = G(x1, x2)G(x2, x1) G(x1, x1)G(x2, x2) , g123 = G(x1, x2)G(x2, x3)G(x3, x1) G(x1, x1)G(x2, x2)G(x3, x3) .(13)
The three-point coincidence rate is then
1 + g12 + g13 + g23 + 2 g123(14)
times the chance coincidence rate. Here the gij terms are the (normalized) power spectrum, 4 while the last term is the bispectrum, whose phase is well known in radio astronomy as the closure phase. Thus, whereas two-detector intensity interferometry only measures amplitudes but no phases, multi-detector combinations are actually sensitive to certain combinations of phases and provide qualitatively new information.
If the detectors are close together, all the terms are equal (gij = g123 = 1), resulting in a six-fold enhancement over the chance coincidence rate. This has been measured in lab experiments (Zhou et al. 2010). At this point, one may get the idea, from the N ! terms in (11), that splitting up a single collecting area into N parts will increase the count rate. But in fact that will not happen. Splitting reduces the count rate in each detector by a factor of N , hence the N -point coincidence rate would be N ! (r ∆τ /N ) N ∝ √ N e −N (r ∆τ ) N , using Stirling's approximation for large N . Let us now estimate the SNR. We have to be careful here, because the combinatorial formulas define the coincidences over ∆τ . We are interested in coincidences over ∆t, and we have seen before in the case of two detectors that random and HBT coincidences scale differently. To take care of this, we have to understand that the intensities that are being correlated are integrated over a duration ∆t consisting of many intervals of ∆τ , and correlations exist only for fields within the same short interval. The N -point HBT signal will therefore be g1. . . N × (r ∆τ ) N (∆t/∆τ ) .
We should emphasize that (15) is not the number of coincidences, but the number that remains after subtracting off the chance coincidence rate and all the lower-order HBT effects. Meanwhile, the chance coincidence rate is
(r ∆t) N .(16)
Hence SNR(N, ∆t) ∼ g1. . . N × (r ∆τ ) N/2 (∆τ /dt) N/2−1
For N = 2 and g12 1 we recover the simple expression (6) for standard HBT.
SUPER-POISSON NOISE
In deriving the expression (17) for the SNR, we assumed that the chance coincidence rate that determines the noise follows Poisson statistics. This is a good assumption for low count rates r dt 1. But for very high photon rates, a new source of noise enters: it is the well-known wave noise from radio-astronomy, and as mentioned in the previous section, it can be considered as HBT correlation at a single space point over different times. Even in the limit of infinitely many photons, the received flux necessarily has to vary with time, because it consists of a finite number of samples from a stochastic process. These fluctuations that form the basis of the HBT effect in the first place eventually also limit its achievable SNR. As we mentioned above, the N -detector coincidence rate includes all the lower-order HBT signals as well. So, in principle, N -detector coincidences could be used to extract the two-point HBT signal. Is it advantageous to do so, compared to standard HBT? To answer this question, let us consider the number of N -detector coincidences over ∆t
r N ∆t N + r N ∆t N −1 ∆τ j<k g jk + . . .(18)
The random coincidences are given by the first term, and two-point HBT gives the next term. In the same way as before, we may derive
SNR(N → 2, ∆t) ∼ Γ × (r∆t) N/2 ∆τ ∆t ,(19)
where Γ denotes the sum in equation (18). Taking many counting times in quadrature and assuming full correlation (g jk = 1), we have, analogous to equation (7),
SNR(N → 2, T ) ∼ N (N − 1) 2 (r∆t) N/2 ∆τ ∆t T ∆t .(20)
If we keep the total collecting area constant but split it into N detectors, so that the individual counting rate goes with r/N we have
SNR(N → 2, T ) SNR(2, T ) = (N − 1) r∆t N N/2−1 .(21)
In the photon-counting regime, r∆t/N < 1, and hence splitting detectors does not help. The situation is different in the case of r∆t/N > 1, in which we may not be able to count individual photons, but can still measure intensities. The SNR would then apparently increase with N . Formally, the optimal number of detectors for r∆t = 1/10/100 is N = 3/7/41 with SNR benefits compared to two detectors of 1.15/14.6/(1.42 × 10 9 ). These numbers at first look extremely promising. But there is a paradox: equation (21) has SNR increasing with ∆t (that is, with coarser time resolution), when r∆t is large enough. Clearly, this estimate based on photon shot noise cannot represent the whole truth, and resolving the paradox requires the inclusion of wave noise. To see the effect of wave noise, let us return to the basic expression (4) of standard HBT, but now let x1, x2 be, not two detector locations, but the same detector at different times. Equation (4) then means the mean-square intensity at a single detector. Let us take this mean square over a time interval ∆t ∆τ . The first term on the right of (4) will contribute (r∆t) 2 . The last term will contribute only if x1, x2 happen to be closer than a coherence time. There are ∆t/∆τ time slices over which that happens, and over each of them, the last term contributes (r∆τ ) 2 . The full contribution of the last term is hence r 2 ∆t ∆τ . The expected photon count at a single detector is thus not constant, but has a variance of r 2 ∆t ∆τ . Its square root is the single-detector wave noise (photon shot noise comes on top of it) and is proportional to intensity, not square-root intensity. It is the single-detector wave noise, also described as super-Poisson noise, and dominates if r∆τ > 1. For each sample of a Gaussian random process (like the field of chaotic light) wave noise limits SNR to order unity. Sampling the same field with larger collecting area does not circumvent this fundamental limit. Even for strong sources, the final SNR can thus never be higher than the square-root of the number of samples. The only chance to increase the SNR is observing for longer or with more bandwidth. This is a well-known (although often neglected) effect in radio astronomy (see e.g., Radhakrishnan 1999).
Generalizing the N -point SNR formula (17) to high photon rates requires generalizing the above single-detector argument to N detectors. We leave a full calculation for a future paper, but the basic conclusion, that SNR over one counting time ∆t cannot exceed unity, remains valid for multiple detectors, no matter how bright the source or how ridiculously large the light collectors.
FLUXES AND COUNT RATES
From the previous section, we see that the number of photons detectable in a coherence time, or r ∆τ , is central to the SNR.
In a passband around ν, a source with flux density Fν gives
r ∆τ Fν hν A,(22)
where A is the collecting area. As mentioned before, the effect of ∆ν cancels between r and ∆τ . Rewriting the expression, mixing wavelength and frequency, in the form
r ∆τ 0.05 × Fν Jy λ m A m 2(23)
makes it easy to compare sources. Bright stars can have Fν ∼ 10 4 Jy, but λ ∼ 10 −6 m. Hence r ∆τ 1 per m 2 . More detailed estimates are shown in Figure 1. On the other hand, bright masers 5 can have Fν ∼ 100 Jy at λ ∼ 1 cm, so a large dish easily receives r ∆τ > 1. Now, intensity interferometry is not needed to resolve masers, because at radio wavelengths it is much easier to control the delays sufficiently accurately for standard interferometry. But high-order HBT using astrophysical masers would be a novel quantum-optics experiment.
Blackbody sources lead to a rather elegant estimate of r ∆τ . Consider a blackbody source at temperature T and angular area Ω on the sky. We detect photons from it using a collector of area A, in a passband ∆λ. For convenience, we will work in terms of a logarithmic passband
∆(ln λ) = ∆λ λ .(24)
We also write
z ≡ hc λkT .(25)
Recall the number density of a photon gas
4π λ 3 ∆(ln λ) e z − 1 .(26)
This is for one polarization state; since we are making rough estimates here, we will disregard the second polarization state.
To get the photon flux, we multiply this by cΩ/(4π) or λνΩ/(4π). The photon arrival rate in an area A is thus
r = ΩA ν λ 2 ∆(ln λ) e z − 1 .(27)
We can rewrite ∆λ in terms of the coherence time (2). The number of photons received in a coherence time is then
r ∆τ ∼ ΩA λ 2 1 e z − 1 .(28)
We can also write r ∆τ in another way. Consider the baseline needed to resolve the source. The square of the baseline is the area Aairy λ 2 /Ω of an aperture whose Airy disc corresponds to the size of the source. This is a natural limit for the collecting area of detectors to just resolve the source and, e.g., measure its size, because larger detectors would require longer baselines and reduce the correlations g so much that the source would be 'resolved out'. With this definition, we have
r ∆τ ≈ A Aairy 1 e z − 1 .(29)
For very small z r ∆τ ≈ A Aairy kT hc λ , λ hc kT .
We see that for an HBT baseline adapted to the source size (that is, A/Aairy fixed), the SNR only depends on λT . Thus, by going far into the Rayleigh-Jeans tail, r∆τ can in principle be made arbitrarily large (with the consequence of increasing wave noise), but in the brightest part of the spectrum r∆τ 1. A simple physical interpretation for the expression (29) is obtained by noting that it is A/Aairy times the phase-space density of photons in blackbody radiation. As result of Liouville's theorem, this phase-space density is conserved when the radiation leaves the sources to travel towards the observer. When increasing the distance, the total flux gets diluted, but at the same time the apparent size of the source shrinks so that the momentum-space density increases, which compensates for the former effect. Aairy is a reciprocal measure for the apparent size of the source, and A/Aairy by definition takes care of both effects. With increasing distance, the light bucket has to grow to pick up more photons, but can also form a smaller field of view and be susceptible to a smaller part of momentum-space. Figure 1 shows the count rate and r ∆τ for three blackbody sources. These have T = 9940 K and angular diameter θ = .007 , which approximates Sirius, T = 4300 K, θ = .02 , similar to Arcturus, and T = 3500 K, and θ = .04 , similar to Betelgeuse. Hanbury Brown & Twiss (1958) measuring Sirius had a collecting area of about 2 m 2 , and quantum efficiency 15% at .4 micron. From Figure 1 we would predict SNR 3 × 10 −5 per counting cycle, less absorption and other losses. The reported value is SNR = 8.5 in 345 minutes, using 5-45 MHz, which corresponds to SNR 1 × 10 −5 per counting cycle.
Equation (29) is not limited to bright stars, however. As a more exotic example of an approximately thermal source, consider the central accreting region of M87 (e.g. Doeleman et al. 2012). The innermost stable orbit lensed by the supermassive black hole has a diameter of the order 50 µ arcsec. Resolving sources of this size at optical wavelengths requires baseline lengths of several kilometres. In order to achieve a similar A/Aairy as in the NSII, collecting areas of several hectares would be needed. Since optical-quality mirrors are not required, such light buckets could be built. Whether such an observation is possible probably depends more on how well the background light from the host galaxy can be excluded.
DISCUSSION
We may expand the title of this paper to two questions. First, is the quantum-optical effect of three-point or higher-order HBT measurable for any astronomical source? If so, would it tell us new things about the source?
Measuring three-point HBT for bright stars appears feasible. Using equation (17)
For visible light with a narrowband filter, the coherence time ∆τ ∼ 10 −12 s. Off-the-shelf photon counters can reach a time resolution of ∆t ∼ 10 −10 s. From Figure 1, a square metre of collecting area gives r∆τ ∼ 10 −4 from a bright star. These numbers suggest SNR ∼ 1 in an hour. For quicker results one would want to increase the collecting area -from (17) we see that T ∝ A −N for a given SNR. As always in HBT, optical-path tolerances need only be c∆t. Three-point HBT would provide the three-point closure phase, or bispectrum, of the source on the sky. Is that worth having? Since two-point HBT gives only the power spectrum, and no phase information, having the bispectrum is likely to be an important advantage for image reconstruction of bright stars.
Going to four or more detectors, for bright stars or any other thermal sources, would be difficult. The geometric estimate (29) of the photon count per coherence time indicates that r ∆τ 1 for any thermal source, except far in the Rayleigh-Jeans tail. But r ∆τ appears at progressively higher powers in the SNR. For non-thermal sources, the situation may be very different. In particular r ∆τ > 1 appears achievable for bright masers. Masers can be imaged using standard radio-telescopes, so HBT may not provide any new information on them. Nonetheless, it would be an interesting physics experiment to look for the combinatorial enhancement of the HBT effect for large N . The total number of photons would not increase, of course, they would just get more and more bunched.
Figure 1 .
1Photon flux (above) and photon flux per coherence time (below) for three blackbody sources, corresponding roughly to Sirius, Arcturus and Betelgeuse. The lower panel leads to simple estimates of signal to noise.
for N = 2 and N = 3 scaled to an integration time T , SNR(T, N = 2) ∼ g12 × (r∆τ ) T ∆t , SNR(T, N = 3) ∼ g123 × (r∆τ )
In a different terminology our 'first-order correlation' would be called 'two-point correlation', and our 'second-order correlation' is a 'four-point correlation'. c 0000 RAS, MNRAS 000, 000-000
It is understood that SNR must also include factors for throughput and detector efficiency (cf. equation 14 in Hanbury Brown 1968). But equation(7)is the essential SNR expression in standard HBT. c 0000 RAS, MNRAS 000, 000-000
In terms of normalized visibilities γ jk , we have g 12 = |γ 12 | 2 and g 123 = γ 12 γ 23 γ 31 . c 0000 RAS, MNRAS 000, 000-000
c 0000 RAS, MNRAS 000, 000-000
For natural masers to show HBT correlation, it is essential that they are not single-mode systems like artificial masers, but rather like chaotic superpositions of laboratory masers. This fact also makes them spatially incoherent so that the usual Fourier relations for the correlations hold. c 0000 RAS, MNRAS 000, 000-000
ACKNOWLEDGMENTSThe authors thank Dan D'Orazio, Richard Porcas and Tina Wentz for discussions.
. G Baym, Acta Physica Polonica B. 291839Baym G., 1998, Acta Physica Polonica B, 29, 1839
. E F Borra, MNRAS. 389364Borra E. F., 2008, MNRAS, 389, 364
. B F Burke, Nature. 223389Burke B. F., 1969, Nature, 223, 389
. S S Doeleman, Science. 338355Doeleman S. S. et al., 2012, Science, 338, 355
. D Dravins, S Lebohec, H Jensen, P D Nuñez, New Astr Rev. 56143Dravins D., LeBohec S., Jensen H., Nuñez P. D., 2012, New Astr Rev, 56, 143
. C Foellmi, A&A. 5071719Foellmi C., 2009, A&A, 507, 1719
. R J Glauber, Phys. Rev. 1312766Glauber R. J., 1963, Phys. Rev., 131, 2766
. R J Glauber, Rev. Mod. Phys. 781267Glauber R. J., 2006, Rev. Mod. Phys., 78, 1267
. Hanbury Brown, R , ARA&A. 613Hanbury Brown R., 1968, ARA&A, 6, 13
. Hanbury Brown, R Jennison, R C Das Gupta, M K , Nature. 1701061Hanbury Brown R., Jennison R. C., Das Gupta M. K., 1952, Nature, 170, 1061
. Hanbury Brown, R Twiss, R Q , Nature. 17727Hanbury Brown R., Twiss R. Q., 1956, Nature, 177, 27
. Hanbury Brown, R Twiss, R Q , Royal Society of London Proceedings Series A. 248222Hanbury Brown R., Twiss R. Q., 1958, Royal Society of London Proceedings Series A, 248, 222
E P Horch, M A Camarata, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series Jain P. 8445887A&AHorch E. P., Camarata M. A., 2012, in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol. 8445, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series Jain P., Ralston J. P., 2008, A&A, 484, 887
. H Kiesel, A Renz, F Hasselbach, Nature. 418392Kiesel H., Renz A., Hasselbach F., 2002, Nature, 418, 392
An Introduction to Astronomical Interferometry. A Labeyrie, S Lipson, P Nisenson, P D Nuñez, R Holmes, D Kieda, S Lebohec, MNRAS. 419172Cambridge University PressLabeyrie A., Lipson S., Nisenson P., 2006, An Introduction to Astronomical Interferometry. Cambridge University Press Nuñez P. D., Holmes R., Kieda D., Lebohec S., 2012, MNRAS, 419, 172
. A Ofir, E N Ribak, MNRAS. 3681646Ofir A., Ribak E. N., 2006a, MNRAS, 368, 1646
. A Ofir, E N Ribak, MNRAS. 3681652Ofir A., Ribak E. N., 2006b, MNRAS, 368, 1652
V Radhakrishnan, Astronomical Society of the Pacific Conference Series. Taylor G. B., Carilli C. L., Perley R. A.180671Radhakrishnan V., 1999, in Astronomical Society of the Pacific Conference Series, Vol. 180, Synthesis Imaging in Radio Astronomy II, Taylor G. B., Carilli C. L., Perley R. A., eds., p. 671
. T Sato, S Wadaka, J Yamamoto, J Ishii, Appl. Opt. 172047Sato T., Wadaka S., Yamamoto J., Ishii J., 1978, Appl. Opt., 17, 2047
. N Sim, M F Cheng, D Bessarab, C M Jones, L A Krivitsky, Phys. Rev. Lett. 109113601Sim N., Cheng M. F., Bessarab D., Jones C. M., Krivitsky L. A., 2012, Phys. Rev. Lett., 109, 113601
. E C G Sudarshan, Phys. Rev. Lett. 10277Sudarshan E. C. G., 1963, Phys. Rev. Lett., 10, 277
. Y Zhou, J Simon, J Liu, Y Shih, Phys. Rev. A. 8143831Zhou Y., Simon J., Liu J., Shih Y., 2010, Phys. Rev. A, 81, 043831
| [
-0.07036913931369781,
-0.04501654580235481,
-0.08079028874635696,
0.12465078383684158,
0.030760236084461212,
-0.04200713708996773,
0.02063560113310814,
0.007316920906305313,
-0.022251099348068237,
-0.06125041842460632,
-0.08155707269906998,
-0.14600056409835815,
0.15217384696006775,
-0.047... |
PyRater: A Python Toolkit for Annotation Analysis
Angelo Basile angelo.basile@symanto.com
Universitat Politècnica de València
Symanto Research 3 ValgrAI -Valencian Graduate School and Research Network of Artificial Intelligence
Marc Franco-Salvador
Symanto Research 3 ValgrAI -Valencian Graduate School and Research Network of Artificial Intelligence
Paolo Rosso
Universitat Politècnica de València
PyRater: A Python Toolkit for Annotation Analysis
AC434724BFC3A2D810EDA81A35393F4B
We introduce PyRater, an open-source Python toolkit designed for analysing corpora annotations.When creating new annotated language resources, probabilistic models of annotation are the state-of-the-art solution for identifying the best annotators, retrieving the gold standard, and more generally separating annotation signal from noise.PyRater offers a unified interface for several such models and includes an API for the addition of new ones.Additionally, the toolkit has built-in functions to read datasets with multiple annotations and plot the analysis outcomes.In this work, we also demonstrate a novel application of PyRater to zero-shot classifiers, where it effectively selects the best-performing prompt.We make PyRater available to the research community.
Introduction
In recent years, the landscape of open-source NLP software has undergone substantial transformation.Custom codebases traditionally released alongside NLP research papers have partially been absorbed into more extensive libraries.To name a few examples, research on Transformer models has been streamlined by the popular Huggingface Transformers library (Wolf et al., 2020); tens of thousands of datasets can be sourced and loaded through the Datasets project (Lhoest et al., 2021); the AllenNLP (Gardner et al., 2018) and fairseq (Ott et al., 2019) projects have provided several foundational components for building custom neural models and sequence-to-sequence models respectively.It is reasonable to speculate that the ease of use of these frameworks has influenced and partially shaped the direction of NLP research.Despite these advancements in model building and data loading, there is still a lack of specialized libraries for annotation analysis.The most common practice for dealing with datasets with multiple annotations is to manage discrepancies using majority voting and to evaluate the quality of the annotations using inter-annotator agreement (IAA) metrics such as Cohen's Kappa (Artstein and Poesio, 2008).Recent studies (Hovy et al., 2013;Passonneau and Carpenter, 2014;Paun et al., 2018;Simpson and Gurevych, 2019) have shown that probabilistic models of annotations -popular in medical research (Dawid and Skene, 1979) -outperform both majority voting and traditional IAA metrics.An annotation merging strategy based on majority voting can fail if most of the annotators converge on the wrong label.Similarly, inter-annotator agreement metrics measure only consistency and not accuracy, implying that a pool of annotators can be consistently wrong; more importantly, agreement metrics cannot account for the different expertise of raters and assign equal value to both expert raters and noisy ones.Annotation models can avoid these pitfalls by jointly estimating directly the gold label, the difficulty of annotating each item and the skills of the raters.Despite these benefits, the use of probabilistic annotation models in NLP is still limited.We believe that one reason for this is the lack of user-friendly tools for the NLP community.This paper introduces a new Python library designed to handle repeated ratings using annotation models, aiming to make these models more accessible for NLP research and applications.More in detail, our contributions are as follows:
• We present PyRater, an easy-to-use and extensible Python library for annotation analysis with probabilistic models;
• We provide an implementation of popular models;
• We present a case study on a novel application of annotation models for unsupervised prompt optimization for zero-shot classifiers.
Annotation Analysis Models
Data annotation is crucial for supervised learning and model evaluation.Ensuring the reliability of annotations can be challenging due to the natural variance in human perspectives and to the objective difficulty of categorizing many linguistic structures (Plank et al., 2014b;Abercrombie et al., 2022).As multiple annotations for a single dataset are often collected to mitigate individual rater biases and provide a more robust label assignment, this introduces the need for a secondary layer of review, either through expert adju-dication or automated methods.Few expert annotators can review smaller datasets, but for larger, crowdsourced projects, manual review becomes impractical.As larger annotated corpora are likely to contain errors (Abad and Moschitti, 2016;Gururangan et al., 2018), automated analysis methods become increasingly important.
In a typical data labelling scenario, we have a dataset of i items, a label space consisting of k classes, and a set of c coders.Each item i in the dataset is annotated with a label k by a coder c; a coder can annotate an instance 0 or more times.Annotation analysis aims to answer the following questions:
Q1 What is the most likely true class k for a given instance i?
Q2 Which instances are more difficult to annotate?
Q3 Among all coders c, who are the most reliable?
The state-of-the-art approach to answering these questions involves fitting a probabilistic generative model to the dataset.These probabilistic models are the core components of PyRater.The model parameters describe various aspects of the process, such as annotator reliability and item difficulty, based on a given annotation matrix.In this matrix, each element a i,c is a label k assigned to an item i by a coder c.Parameter estimation, conditioned on observed annotations, is performed through Bayesian inference.In PyRater, the full posterior distribution of the model parameters is estimated using the probabilistic programming language Stan (Carpenter et al., 2017).Listing 1: An overview of a PyRater workflow.
Library Overview
Design A high-level overview of an annotation analysis workflow with PyRater is provided in Listing 1.The focus of this work is twofold: i) to enable interoperability between diverse annotation models and ii) to improve the accessibility of these models.To achieve the first goal, PyRater defines a common API, as shown in Listing 2, and employs a registry system via Tango (Groeneveld et al., 2023).This allows users to easily list and register available models, as outlined in Listing 3.For the second goal, the library aligns loosely with the scikit-learn Model API (Pedregosa et al., 2011) Examples Several examples and tutorials for users are included in PyRater.These tutorials are available as easy-to-run Python notebooks.While the primary focus is on human annotation modeling, the examples also extend to other applications like dataset cartography (Swayamdipta et al., 2020) and prompt optimization (briefly presented in Section 4).To ensure the examples are selfcontained, the library includes datasets with multiple annotations that are ready to be loaded.Models PyRater includes implementations of several models that are ready to use and also serve as a reference for the development of new models.A registry system makes it possible to list all the available models:
from pyrater import PyRaterModel as pm class PyRaterModel : def fit (...): ... @property () def labels () """ Return the predicted true labels .This can answer Q1: given multiple annotations for an instance , which is the true label ?""" ... @property () def difficulty () """ Return the predicted difficulty of each item.This can answer Q2: which are the most difficult instances to label ?""" ... @property () def credibilities () """ Return the credibility of each rater .This can answer Q3: how is the best rater ?""" ...
Listing 2: A partial view of the main PyRater-Model class.
After fitting, the object exposes the labels(), difficulty() and credibilities() methods that can be used to address the most common problems in annotation analysis.Jittering is added for enhanced readability.
face:
$ pyrater [ OPTIONS ] -m MODEL <input file >
Case Study: Unsupervised Prompt Optimization
In addition to analyzing human annotations, Pyrater can also be used for scenarios that involve repeated model predictions.This is particularly relevant for prompt selection in zero-shot models.In a genuine zero-shot environment, selecting the optimal prompt is challenging due to the lack of labeled development data.A solution to this issue involves collecting repeated predictions from a zero-shot model prompted in different ways.Pyrater can then analyze these multiple predictions and i) estimate the performance of different prompts and ij) predict the true label, effectively simulating an ensemble model.
In this section, we conduct a case study on prompt selection, using the Yelp (Zhang et al., 2015) and IMDb (Maas et al., 2011) binary sentiment analysis datasets and a dual-encoder architecture (sentence-t5-large, (Ni et al., 2022) ) for zeroshot learning.First, we craft a diverse set of prompts per class, as shown in Table 1.Second, we assess how the model's performance varies depending on the selected prompts.Next, we evaluate how the inferred gold labels using PyRater contrast with those obtained through simple majority voting.Finally, we investigate the correlation between predicted prompt reliability and the model's true accuracy, evaluated using gold label data.
Positive Negative
this is good quite bad text is great this is terrible very positive very negative … …
Table 1: Sample Label Descriptions for binary sentiment analysis.
Dual-encoder zero-shot classifiers (Müller et al., 2022) work by calculating the similarity between the embedding of an input text and label descriptions, commonly referred to as prompts.The class corresponding to the label description that is closest to the input text is selected as the predicted class.For binary sentiment classification tasks, the user begins by crafting a label description for each class: for instance, This text is positive and This text is negative could serve as label descriptions for the positive and negative classes, respectively.Such zero-shot classifiers are sensitive to the phrasing of label descriptions: well-crafted but differently phrased descriptions can result in significant performance variations (Shin et al., 2020;Lu et al., 2022).Figure 1 illustrates the distribution of scores for the same model when prompted with different label descriptions.As observed, the performance can vary widely, ranging from nearly random to approaching the state-of-the-art.When multiple plausible label descriptions are available and labeled data cannot be used to identify the bestperforming description, the situation becomes analogous to human annotation analysis.However, in this case, the "annotations" are zero-shot model predictions rather than human ratings.We evaluate PyRater on two tasks: label prediction, assessed by accuracy (Q1), and prompt ranking, evaluated by Pearson coefficients (Q2).As shown in Table 2, the model-based approach significantly outperforms both the Kappa agreement metric and majority voting.The correlation parameters for the ranking task -0.83 for Yelp and 0.94 for IMDB -indicate that probabilistic models can accurately select the best prompt from a pool of available options, largely outperforming ranking using Kappa.rics become less reliable with larger, noisy annotation sets (Passonneau and Carpenter, 2014;Paun et al., 2018).As crowdsourcing platforms like Mechanical Turk gained popularity for annotation tasks (Callison-Burch and Dredze, 2010), the use of annotation models in NLP has increased (Snow et al., 2008;Hovy et al., 2013) to maintain the quality of expert annotators using a broader set of noisy raters.Concurrently, separate research lines aim to avoid the annotation analysis and label adjudication steps by directly training models on multiple labels per instance, rather than a single, aggregated one (Plank et al., 2014a;Rodrigues and Pereira, 2018;Fornaciari et al., 2021).For a comprehensive overview of statistical annotation analysis, readers are advised to refer to Paun et al. (2022).NLP Open Source Software Although various implementations of models for annotation analysis are available (Hovy et al., 2013;Pullin, Jeffrey and Vukcevic, Damjan and Saxhaug, Lars-Mølgaard, 2020;Simpson and Gurevych, 2019;Carpenter, 2013), a dedicated, comprehensive framework is still lacking2 .This work synthesizes ideas from two lines of existing libraries.First, like Transformers and AllenNLP, it consolidates various implementations under a unified interface.Second, in terms of user experience, it draws inspiration from the simplicity and ease of use found in NLTK (Loper and Bird, 2002) and scikit-learn (Pedregosa et al., 2011).Applications to NLP Models Basile et al. (2022) discuss the application of annotation models to zero-shot classifiers, and similar efforts have been made in the context of few-shot models (Zhao et al., 2022) and ensemble learning (Simpson et al., 2013).
Related Work
Conclusion and Future Work
We introduced PyRater, an open-source library designed to simplify annotation analysis.We believe PyRater will facilitate broader adoption of state-of-the-art annotation models.Going forward, we welcome community feedback to inform the development of future features for PyRater.
Figure 1 :
1
Figure 1: Accuracy score distributions for IMDB and Yelp using different prompts.Each point denotes zero-shot model accuracy.In red: the best and worst scores, each annotated with its corresponding prompt text.+ and -denote the prompt for the positive and negative class, respectively.Jittering is added for enhanced readability.
Table 2 :
2
Performance comparison on Yelp and IMDb datasets.The ranking metric is Pearson correlation coefficient.
Annotation Analysis While probabilistic, genera-tive models of annotation have been extensivelyapplied in fields such as psychometrics, epidemi-ology, and education, their adoption in NLP re-mains relatively limited. In contrast, NLP re-searchers frequently rely on agreement metricslike Kappa (Artstein and Poesio, 2008). Althoughsuitable for small pools of expert raters, these met-
https://developer.nvidia.com/cuda-toolkit
It is worth noting that the probabilistic programming library Numpyro(Phan et al., 2019) lists several annotation models in its example documentation.
AcknowledgementsWe thank the anonymous reviewers for their helpful comments.The work of Paolo Rosso was in the framework of the FairTransNLP research project (PID2021-124361OB-C31), funded by MCIN/AEI/10.13039/501100011033and by ERDF, EU A way of making Europe.The work from Symanto has been partially funded by the Pro 2 Haters -Proactive Profiling of Hate Speech Spreaders (CDTi IDI-20210776), the XAI-DisInfodemics: eXplainable AI for disinformation and conspiracy detection during infodemics (MICIN PLEC2021-007681) and the ANDHI -ANomalous Diffusion of Harmful Information (CPP2021-008994) R&D grants.
Taking the best from the crowd:learning question passage classification from noisy data. Bibliographical References, Azad Abad, Alessandro Moschitti, 10.18653/v1/S16-2018Proceedings of the Fifth Joint Conference on Lexical and Computational Semantics. the Fifth Joint Conference on Lexical and Computational SemanticsBerlin, GermanyAssociation for Computational Linguistics2016
Vincent Vanhoucke, Vijay Vasudevan, Fernanda Viégas, Oriol Vinyals. Martín Abadi, Ashish Agarwal, Paul Barham, Eugene Brevdo, Zhifeng Chen, Craig Citro, Greg S Corrado, Andy Davis, Jeffrey Dean, Matthieu Devin, Sanjay Ghemawat, Ian Goodfellow, Andrew Harp, Geoffrey Irving, Michael Isard, Yangqing Jia, Rafal Jozefowicz, Lukasz Kaiser, Manjunath Kudlur, Josh Levenberg, Dandelion Mané, Rajat Monga, Sherry Moore, Derek Murray, Chris Olah, Mike Schuster, Jonathon Shlens, Benoit Steiner, Ilya Sutskever, Kunal Talwar, Paul Tucker, 2015Yuan Yu, and Xiaoqiang ZhengPete Warden, Martin Wattenberg, Martin WickeTensorFlow: Large-scale machine learning on heterogeneous systems. Software available from tensorflow.org
Survey article: Inter-coder agreement for computational linguistics. Gavin Abercrombie, Valerio Basile, Sara Tonelli, 10.1162/coli.07-034-R22022. Proceedings of the 1st Workshop on Perspectivist Approaches to NLP @LREC2022. Verena Rieser, Alexandra Uma, Marseille, France200834Computational Linguistics
Unsupervised ranking and aggregation of label descriptions for zero-shot classifiers. Angelo Basile, Marc Franco-Salvador, Paolo Rosso, International Conference on Applications of Natural Language to Information Systems. Springer2022
Proceedings of the NAACL HLT 2010 Workshop on Creating Speech and Language Data with Amazon's Mechanical Turk. Association for Computational Linguistics. Chris Callison, - Burch, Mark Dredze, the NAACL HLT 2010 Workshop on Creating Speech and Language Data with Amazon's Mechanical Turk. Association for Computational LinguisticsLos Angeles2010
2013. pyanno. python package for dawid and skene (1979) maximum likelihood estimator for categorical data coding models. Bob Carpenter,
Stan: A probabilistic programming language. Bob Carpenter, Andrew Gelman, Matthew D Hoffman, Daniel Lee, Ben Goodrich, Michael Betancourt, Marcus Brubaker, Jiqiang Guo, Peter Li, Allen Riddell, 10.18637/jss.v076.i01Journal of Statistical Software. 7612017
The pascal recognising textual entailment challenge. Ido Dagan, Oren Glickman, Bernardo Magnini, 10.1007/11736790_9Proceedings of the First International Conference on Machine Learning Challenges: Evaluating Predictive Uncertainty Visual Object Classification, and Recognizing Textual Entailment, MLCW'05. the First International Conference on Machine Learning Challenges: Evaluating Predictive Uncertainty Visual Object Classification, and Recognizing Textual Entailment, MLCW'05Berlin, HeidelbergSpringer-Verlag2005
Maximum likelihood estimation of observer error-rates using the em algorithm. Alexander Philip, Dawid , Allan M Skene, Journal of the Royal Statistical Society: Series C (Applied Statistics). 2811979
Beyond black & white: Leveraging annotator disagreement via softlabel multi-task learning. Tommaso Fornaciari, Alexandra Uma, Silviu Paun, Barbara Plank, Dirk Hovy, Massimo Poesio, 10.18653/v1/2021.naacl-main.204Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies. the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language TechnologiesOnline. Association for Computational Linguistics2021
AllenNLP: A deep semantic natural language processing platform. Matt Gardner, Joel Grus, Mark Neumann, Oyvind Tafjord, Pradeep Dasigi, Nelson F Liu, Matthew Peters, Michael Schmitz, Luke Zettlemoyer, 10.18653/v1/W18-2501Proceedings of Workshop for NLP Open Source Software (NLP-OSS). Workshop for NLP Open Source Software (NLP-OSS)Melbourne, AustraliaAssociation for Computational Linguistics2018
. Dirk Groeneveld, Akshita Bhagia, Pete Walsh, 20232
Annotation artifacts in natural language inference data. Suchin Gururangan, Swabha Swayamdipta, Omer Levy, Roy Schwartz, Samuel Bowman, Noah A Smith, 10.18653/v1/N18-2017Proceedings of the 2018 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies. Short Papers. the 2018 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language TechnologiesNew Orleans, LouisianaAssociation for Computational Linguistics20182
Learning whom to trust with MACE. Dirk Hovy, Taylor Berg-Kirkpatrick, Ashish Vaswani, Eduard Hovy, Proceedings of the 2013 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies. the 2013 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language TechnologiesAtlanta, GeorgiaAssociation for Computational Linguistics2013
Datasets: A community library for natural language processing. Quentin Lhoest, Albert Villanova Del Moral, Yacine Jernite, Abhishek Thakur, Suraj Patrick Von Platen, Julien Patil, Mariama Chaumond, Julien Drame, Lewis Plu, Joe Tunstall, Mario Davison, Gunjan Šaško, Bhavitvya Chhablani, Simon Malik, Brandeis, Le Teven, Victor Scao, Canwen Sanh, Nicolas Xu, Angelina Patry, Philipp Mcmillan-Major, Sylvain Schmid, Clément Gugger, Théo Delangue, Lysandre Matussière, Stas Debut, Pierric Bekman, Thibault Cistac, Victor Goehringer, François Mustar, Alexander Lagunas, Thomas Rush, Wolf, 10.18653/v1/2021.emnlp-demo.21Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing: System Demonstrations. the 2021 Conference on Empirical Methods in Natural Language Processing: System DemonstrationsDominican RepublicAssociation for Computational Linguistics2021Online and Punta Cana
Edward Loper, Steven Bird, Nltk: The natural language toolkit. 2002
Fantastically ordered prompts and where to find them: Overcoming few-shot prompt order sensitivity. Yao Lu, Max Bartolo, Alastair Moore, Sebastian Riedel, Pontus Stenetorp, 10.18653/v1/2022.acl-long.556Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics. Long Papers. the 60th Annual Meeting of the Association for Computational LinguisticsDublin, IrelandAssociation for Computational Linguistics20221
Learning word vectors for sentiment analysis. Andrew L Maas, Raymond E Daly, Peter T Pham, Dan Huang, Andrew Y Ng, Christopher Potts, Proceedings of the 49th Annual Meeting of the Association for Computational Linguistics: Human Language Technologies. the 49th Annual Meeting of the Association for Computational Linguistics: Human Language TechnologiesPortland, Oregon, USAAssociation for Computational Linguistics2011
Few-shot learning with Siamese networks and label tuning. Thomas Müller, Guillermo Pérez-Torró, Marc Franco-Salvador, 10.18653/v1/2022.acl-long.584Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics. Long Papers. the 60th Annual Meeting of the Association for Computational LinguisticsDublin, IrelandAssociation for Computational Linguistics20221
Sentence-t5: Scalable sentence encoders from pre-trained text-to-text models. Jianmo Ni, Gustavo Hernandez Abrego, Noah Constant, Ji Ma, Keith Hall, Daniel Cer, Yinfei Yang, 10.18653/v1/2022.findings-acl.146Findings of the Association for Computational Linguistics: ACL 2022. Dublin, IrelandAssociation for Computational Linguistics2022
Pymc: A modern and comprehensive probabilistic programming framework in python. Abril-Pla Oriol, Andreani Virgile, Carroll Colin, Dong Larry, Fonnesbeck Christopher, J , Kochurov Maxim, Lao Kumar Ravin, Luhmann Jupeng, C Christian, Martin Osvaldo, A , Osthege Michael, Ricardo Vieira, Wiecki Thomas, Zinkov Robert, 10.7717/peerj-cs.1516PeerJ Computer Science. 9e15162023
fairseq: A fast, extensible toolkit for sequence modeling. Myle Ott, Sergey Edunov, Alexei Baevski, Angela Fan, Sam Gross, Nathan Ng, David Grangier, Michael Auli, 10.18653/v1/N19-4009Proceedings of the 2019 Conference of the North American Chapter of the Association for Computational Linguistics (Demonstrations). the 2019 Conference of the North American Chapter of the Association for Computational Linguistics (Demonstrations)Minneapolis, MinnesotaAssociation for Computational Linguistics2019
The benefits of a model of annotation. Rebecca J Passonneau, Bob Carpenter, 10.1162/tacl_a_00185Transactions of the Association for Computational Linguistics. 22014
Statistical methods for annotation analysis. Ron Silviu Paun, Massimo Artstein, Poesio, 2022Springer Nature
Comparing Bayesian models of annotation. Bob Silviu Paun, Jon Carpenter, Dirk Chamberlain, Udo Hovy, Massimo Kruschwitz, Poesio, 10.1162/tacl_a_00040Transactions of the Association for Computational Linguistics. 62018
Scikit-learn: Machine learning in Python. F Pedregosa, G Varoquaux, A Gramfort, V Michel, B Thirion, O Grisel, M Blondel, P Prettenhofer, R Weiss, V Dubourg, J Vanderplas, A Passos, D Cournapeau, M Brucher, M Perrot, E Duchesnay, Journal of Machine Learning Research. 122011
Composable effects for flexible and accelerated probabilistic programming in numpyro. Du Phan, Neeraj Pradhan, Martin Jankowiak, arXiv:1912.115542019arXiv preprint
Learning part-of-speech taggers with inter-annotator agreement loss. Barbara Plank, Dirk Hovy, Anders Søgaard, 10.3115/v1/E14-1078Proceedings of the 14th Conference of the European Chapter. the 14th Conference of the European ChapterGothenburg, SwedenAssociation for Computational Linguistics2014a
Linguistically debatable or just plain wrong?. Barbara Plank, Dirk Hovy, Anders Søgaard, 10.3115/v1/P14-2083Proceedings of the 52nd Annual Meeting of the Association for Computational Linguistics. the 52nd Annual Meeting of the Association for Computational LinguisticsBaltimore, MarylandAssociation for Computational Linguistics2014b2Short Papers)
Jeffrey Pullin, Damjan Vukcevic, Lars-Mølgaard Saxhaug, rater: Statistical models of repeated categorical rating data. 2020
Deep learning from crowds. Filipe Rodrigues, Francisco Pereira, 10.1609/aaai.v32i1.11506Proceedings of the AAAI Conference on Artificial Intelligence. the AAAI Conference on Artificial Intelligence201832
AutoPrompt: Eliciting Knowledge from Language Models with Automatically Generated Prompts. Taylor Shin, Yasaman Razeghi, Robert L Logan, I V , Eric Wallace, Sameer Singh, 10.18653/v1/2020.emnlp-main.346Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP). the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP)Association for Computational Linguistics2020
A Bayesian approach for sequence tagging with crowds. Edwin Simpson, Iryna Gurevych, 10.18653/v1/D19-1101Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP). the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP)Hong Kong, ChinaAssociation for Computational Linguistics2019
Dynamic bayesian combination of multiple imperfect classifiers. Decision making and imperfection. Edwin Simpson, Stephen Roberts, 2013Ioannis Psorakis, and Arfon Smith
Cheap and fast -but is it good? evaluating non-expert annotations for natural language tasks. Rion Snow, O' Brendan, Daniel Connor, Andrew Jurafsky, Ng, Proceedings of the 2008 Conference on Empirical Methods in Natural Language Processing. the 2008 Conference on Empirical Methods in Natural Language ProcessingHonolulu, HawaiiAssociation for Computational Linguistics2008
Dataset cartography: Mapping and diagnosing datasets with training dynamics. Swabha Swayamdipta, Roy Schwartz, Nicholas Lourie, Yizhong Wang, Hannaneh Hajishirzi, Noah A Smith, Yejin Choi, 10.18653/v1/2020.emnlp-main.746Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP). the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP)Online. Association for Computational Linguistics2020
Transformers: State-of-the-art natural language processing. Thomas Wolf, Lysandre Debut, Victor Sanh, Julien Chaumond, Clement Delangue, Anthony Moi, Pierric Cistac, Tim Rault, Remi Louf, Morgan Funtowicz, Joe Davison, Sam Shleifer, Clara Patrick Von Platen, Yacine Ma, Julien Jernite, Canwen Plu, Teven Xu, Sylvain Le Scao, Gugger, 10.18653/v1/2020.emnlp-demos.6Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing: System Demonstrations. the 2020 Conference on Empirical Methods in Natural Language Processing: System DemonstrationsOnline. Association for Computational Linguistics2020Mariama Drame, Quentin Lhoest, and Alexander Rush
Character-level convolutional networks for text classification. Xiang Zhang, Junbo Zhao, Yann Lecun, Advances in Neural Information Processing Systems. Curran Associates, Inc201528
LMTurk: Few-shot learners as crowdsourcing workers in a language-model-as-aservice framework. Mengjie Zhao, Fei Mi, Yasheng Wang, Minglei Li, Xin Jiang, Qun Liu, Hinrich Schuetze, 10.18653/v1/2022.findings-naacl.51Findings of the Association for Computational Linguistics: NAACL 2022. Seattle, United StatesAssociation for Computational Linguistics2022
| [
-0.20102378726005554,
-0.047392331063747406,
-0.002431989647448063,
0.005448969546705484,
0.1915142834186554,
-0.07437483221292496,
-0.0294270571321249,
0.012089251540601254,
0.0031213073525577784,
-0.017184380441904068,
-0.0442671924829483,
-0.1302313655614853,
-0.009986067190766335,
0.08... |
Modified Einstein equations from the 1-loop effective action of the IKKT model
July 1, 2023
Kaushlendra Kumar kumarkau@physik.hu-berlin.de
Institute of Theoretical Physics
Leibniz University Hannover Appelstraße 2
A-30167HannoverGermany
Erwin Schrödinger Institute for Mathematics and Physics
University of Vienna
Harold C Steinacker harold.steinacker@univie.ac.at
Department of Physics
University of Vienna
Boltzmanngasse 5A-1090ViennaAustria
Institute of Physics
Humboldt University
Zum Großen Windkanal 212489Berlin
Modified Einstein equations from the 1-loop effective action of the IKKT model
July 1, 20232794F9A09F4E30E800018A82705DFC70arXiv:2312.01317v1[hep-th]
We derive the equations of motion that arise from the one-loop effective action for the geometry of 3+1 dimensional quantum branes in the IKKT matrix model.These equations are cast into the form of generalized Einstein equations, with extra contributions from dilaton and axionic fields, as well as a novel anharmonicity tensor C µν capturing the classical Yang-Mills-type action.The resulting gravity theory approximately reduces to general relativity in some regime, but differs significantly at cosmic scales, leading to an asymptotically flat FLWR cosmological evolution governed by the classical action.
Introduction
The problem of embedding gravity in a consistent quantum theory is one of the big questions in theoretical physics.The accepted phenomenological description of gravity is given by general relativity (GR), where the geometry of space-time is related to matter via the Einstein equations.However, GR does not admit straightforward quantization, and it is plausible that the underlying quantum theory is based on very different degrees of freedom, such as strings or matrices.
One specific proposal for such an underlying quantum theory is the IKKT matrix model, which is related to IIB string theory [1,2].As such, it can be viewed as a "holographic" model for 9+1 dimensional gravity on target space, leading to the standard issues of compactification and its inherent ambiguities, cf.[3,4].However, this model also admits a different, weakly coupled approach to 3+1 dimensional gravity on suitable space-time branes via quantum effects.This approach is in the spirit of noncommutative gauge theory (cf.[5,6,7,8,9,10,11,12] and references therein), where target space has no direct physical meaning, and is not inhabited by propagating fields; it therefore does not need to be compactified.
Within that framework, it was shown recently [13,14] that the one-loop effective action indeed contains the Einstein-Hilbert action, supplemented by additional terms and degrees of freedom.This requires an extra compact "fuzzy" factor K N in the underlying background brane configuration, which arises via the Higgs effect in the nonabelian sector of the theory.However, the fundamental degrees of freedom are different from GR: The effective frame and metric are derived objects, which arise from derivatives of some underlying gauge fields given by the matrix background.Accordingly, the Yang-Mills-type matrix model action has two derivatives less than the induced Einstein-Hilbert action.This is a very non-standard situation, and it is not evident how to obtain an intuitive set of equations that capture the combined one-loop effective action.In particular, it does not suffice to consider the variation of the action w.r.t. the frame or the metric, since those are neither fundamental nor independent.
The present paper is a first step to address this problem.We derive geometric equations of motion from the combined one-loop effective action computed in [14], and cast them into a form as close to the Einstein equations as possible.This is achieved by introducing a novel "anharmonicity" tensor C µν , which measures the deviation of the geometry from the Yang-Mills equations.This can then be viewed as a novel term on the rhs of the effective Einstein-like equations.The resulting gravity theory thus behaves similar to general relativity (apart from extra degrees of freedom) as long as C µν is negligible, but displays a rather different behavior at cosmic scales: In particular, it yields a non-standard evolution of FLRW space-times, which is rather insensitive to the detailed matter content.However, the full theory resulting from the present framework is very rich, and a satisfactory understanding of this theory will require much more work.This paper is organized as follows: Section 2 provides a short summary of the basic structure of the present approach, followed by the one-loop effective action in Section 3. The new results of this paper are given in Section 4, where we derive the equations of motion governing the geometry, and discuss some of its aspects.Some remaining open issues are discussed in Section 5, while several of the technical steps and supplementary comments are delegated to the appendix.
Semi-classical geometry of the IKKT matrix model
The IKKT matrix model, defined in terms of bosonic matrices T α with α = 0, . . ., 9 and fermionic matrix-valued spinors Ψ, is given by the following action [1]
S[T, Ψ] = 1 g 2 Tr [T α, T β ][T α, T β ] + ΨΓ α[T α, Ψ] (2.1)
where g 2 is a coupling constant.This model can be viewed as a constructive definition of critical IIB string theory with target space R 1,9 ; here we simply consider it as the fundamental starting point.The action admits several symmetries: We will ignore the fermionic part in the following (apart from its contribution to the one-loop effective action), and focus on backgrounds defined by non-trivial matrix configurations T α ∈ End(H) acting on some Hilbert space H.The classical equation of motion takes the form
T β = [T α, [T α, T β ]] = 0 ,(2.2)
where := [T α, [T α, •]] is the matrix d'Alembertian.We will absorb the coupling constant g 2 in the matrices, since the self-interaction strength of the physical fluctuations becomes meaningful only on some given specific background; such interactions will not be important in the following.
Many non-trivial matrix configurations T α -and in particular solutions for the above eom (2.2) -can be interpreted as (quantized) embedding maps of some brane configurations in the target space R 1,9 :
T α : M ֒→ R 1,9 .
(2.3)
We restrict ourselves to the semi-classical regime in this paper, where matrices or operators can be interpreted as quantized functions on some underlying symplectic space.This identification will be indicated by ∼ in the following.Then ✷ reduces to a second-order differential operator
✷ ∼ −{T α, {T α, •}} (2.4)
which will play the role of the d'Alembertian on suitable backgrounds.We will study the geometrical equations of motion that determine such backgrounds at one loop, focusing on 3+1 dimensional backgrounds defined by T ȧ with ȧ = 0, . . ., 3, corresponding to branes
M 1,3 ֒→ R 1,9
. These branes are interpreted as a (quantized) space-time.Fluctuations on such backgrounds are then parametrized as
T ȧ = T ȧ + A ȧ ,(2.5)
which can be interpreted in terms of tangential gauge fields propagating along M 1,3 , as well as transversal fluctuations interpreted in terms of scalar fields on the brane.We will consider not only such "basic" 3+1 dimensional branes with vanishing transversal fields, but also branes with non-vanishing VEV of the transversal fields, interpreted as compact fuzzy extra dimensions K.The latter is essential to obtain an induced Einstein-Hilbert action, and will be denoted as type II branes in section 2.2.
Effective metric, frame and torsion
The fluctuations of some background solutions T ȧ (2.5) is governed by a universal effective metric G µν , which arises from the kinetic term of the action 3 (2.1) in the semi-classical limit
T i ∼ φ (2.22): Tr [T ȧ, T i ][T ȧ, T i ] ∼ d 4 x |G µν | G µν ∂ µ φ ∂ ν φ ,(2.6)
where |G µν | denotes the metric determinant.This effective metric G µν is suitably expressed in terms of a conformally related auxiliary metric γ µν as
G µν = ρ 2 γ µν . (2.7)
Here γ µν is given by
γ µν := η ȧḃ E µ ȧ E ν ḃ with (η ȧḃ ) = diag(−1, 1, 1, 1) ,(2.8)
built from the frame E µ ȧ ; the latter is associated with the background configuration T ȧ ∼ t ȧ (2.22):
E µ ȧ = {t ȧ, x µ } (2.9)
where x µ are local coordinates on M 1,3 .The corresponding coframe E ȧ µ obeys following
conditions 4 E µ ȧ E ḃ µ = δ ḃ ȧ and E µ ȧ E ȧ ν = δ µ ν .
(2.10)
The conformal factor above is given by a dilaton field ρ, which is determined in terms of the metric as follows (see Appendix B for details),
ρ 2 = |G µν | ρ M = ρ M |E µ ȧ | . (2.11)
The density ρ M arises from the volume form Ω = d 4 x ρ M of the symplectic (semi-classical) manifold, which relates the trace of operators End(H) ∋ Φ ∼ φ (2.22) to the integral via
Tr(Φ) ∼ M Ω φ = M d 4 xρ M φ .
(2.12)
The frame E µ α turns out to obey a divergence constraint
∂ ν (ρ M E ν ȧ ) = 0 ,(2.13)
which arises from the Jacobi identity.The existence of this constraint means that the frame E µ ȧ does not admit local Lorentz (gauge) invariance.As a consequence, this frame has more physical content than in usual GR, such as an associated tensor two-form5 T ȧ := dE ȧ with E ȧ=E ȧ µ dx µ :
T ȧ = 1 2 T ȧ µν dx µ ∧dx ν . (2.14)
The matrix model origin of this tensor can be attributed to the symplectic flow generated by θ ȧḃ (2.24):
−{θ ȧḃ , x µ } =: T ȧḃ µ = −E ȧν ∂ ν E ḃµ + E ḃν ∂ ν E ȧµ , T ȧ µν = ∂ µ E ȧ ν − ∂ ν E ȧ µ (2.15)
using the Jacobi identity in the first line and raising/lowering indices with the frame to get the expression in the second line, which is compatible with (2.14).This tensor can also be understood geometrically as the torsion of the Weitzenböck connection ∇ associated with the frame E ȧ, with connection coefficients Γ σ µν given by [15,16] ∇
µ E ν ȧ = 0 =⇒ Γ σ µν = −E ȧ ν ∂ µ E σ ȧ .
(2.16)
The totally antisymmetric part of the torsion
T (AS)ν ρµ = T ν ρµ + T ν µ ρ + T ν ρµ with T ρ µν = T ȧ µν E ρ ȧ (2.17)
defines an "axionic vector field" T µ via Hodge-dualilty w.r.t the effective metric G µν :
T σ dx σ =: T = − ⋆ T (AS) for T (AS) = 1 3! G νν ′ T (AS)ν ρµ dx ν ′ ∧dx ρ ∧dx µ . (2.18)
As a result, we have the following expression for T σ ,
T σ := − 1 3! |G µν | ε νµρσ G µµ ′ G ρρ ′ T (AS)ν µ ′ ρ ′ . (2.19)
Then the equations of motion of the semi-classical matrix model imply that T µ can be reduced to an axion field ρ via [16]
ρ 2 T µ = ∂ µ ρ . (2.20)
Background geometry and Yang-Mills action
We will consider two basic types of backgrounds denoted by type I and type II branes.
Brane I: M 1,3 ×S 2 n as equivariant bundle.An interesting class of solutions 6 to eom (2.2) is given by the following matrix configuration with four non-vanishing components:
T ȧ = 1 R M ȧ4 , ȧ = 0, ..., 3(2.21)
with the remaining T i = 0.Here the matrices M ȧ4 are part of the SO(2, 4) generators, M ab ∈ End(H n ) with a, b = 0, . . ., 5, that belong to unitary irreducible representations H n known as the doubleton series and are labeled by n ∈ N. One can then identify the quantum space of operators End(H n ) on the associated Hilbert space with the classical space of functions C(CP 1,2 ) [17]:
C(CP 1,2 ) ∼ = End(H n ) . (2.22)
The underlying 6-dimensional symplectic manifold CP 1,2 turns out to be an SO(3, 1)equivariant7 bundle CP 1,2 over the spacetime M 1,3 with fuzzy 2-spheres S 2 n acting as fibres, known as twistor space.This leads to a structure denoted as (semi-classical) covariant quantum space,
CP 1,2 loc ∼ = M 1,3 × S 2 n ,(2.23)
where M 1,3 is generated by Cartesian coordinates x µ , while S 2 n is generated by generators t µ , which also serve as momentum generators and define the undeformed semi-classical background matrices T ȧ ∼ t ȧ [17].The semi-classical regime arises in the limit n → ∞, where the matrix commutators reduce to Poisson brackets [•, •] → i{•, •} as follows:
Θ ȧḃ := −i [T ȧ, T ḃ] ∼ {t ȧ, t ḃ} =: θ ȧḃ .
(2.24)
M 1,3 also acquires an effective metric describing a cosmological FLRW background with negative spatial curvature and a global length scale set by R. The latter should be determined dynamically using the 1-loop effective action, or simply by introducing a mass parameter in the model.
Explicitly, the effective metric and the dilaton on M 1,3 are found to be [17]
G µν = sinh(η)η µν , ρ 2 = sinh 3 (η) (2.25)
in Cartesian coordinates, which corresponds to an FLRW space-time with scale parameter
a(t) ∼ ρ ∼ 3 2 t (2.26)
at late times.More details about this cosmological space-time can be found in [18].
Fluctuations.Now consider the fluctuations on M 1,3 .A generic fluctuation A µ (2.5) can be expressed in terms of functions A ∼ φ on CP 1,2 via the duality (2.22), expanded into S 2 harmonics Y sm as
φ = n s=0 s m=−s φ sm (x) Y sm .
(2.27)
The spin s here are eigenmodes of the S 2 n -Laplacian arising from the decomposition of ✷ (2.2):
✷ = ✷ M 1,3 + m 2 s , with m 2 s = 3s R 2 .
(2.28)
This analysis prompts one to study the higher spin gauge theory through the splitting of the algebra,
C = s≥0 C s ,(2.29)
into higher-spin modules C s .We will largely ignore this higher spin part in the following, except for their contribution to the one-loop computation.
Brane II: M 1,3 ×S 2 n × K with compact K. To obtain induced gravity, we also consider another matrix configuration T α with an extra compact brane K embedded in the transversal dimensions of target space R 1,9 .This arises from the background given by
T ȧ ∼ x ȧ : M 1,3 ֒→ R 1,3 , ȧ = 0, ..., 3(2.30)
describing the quantum spacetime M 1,3 embedded along the first 3+1 directions, and some compact quantum space K (such as a fuzzy sphere) embedded along the remaining 6 directions as
T i ∼ z i : K ֒→ R 6 , i = 4, . . . , 9 .
(2.31)
The exact structure of K is not relevant for our discussion except for the finite, discrete (positive) spectrum, labeled by Λ, of its Laplacian ✷ K arising from the splitting
✷ = ✷ M 1,3 + ✷ K (2.2): ✷ K λ Λ = m 2 Λ λ Λ , m 2 Λ = m 2 K µ 2 Λ (2.32) associated with eigenmodes λ Λ ∈ End(H K ) 8
. The matrices then act on the product Hilbert space
H = H M 1,3 ⊗ H K , where H K is finite-dimensional. We can expand generic fluctuations A ∼ φ ∈ End(H) in term of the Kaluza-Klein (KK) modes as φ = Λ φ Λ λ Λ (2.33)
where φ Λ ∈ End(H M 1,3 ).This product background induces a mass for the KK modes φ Λ on space-time:
✷φ Λ = (✷ M + m 2 Λ )φ Λ . (2
.34)
The semi-classical Yang-Mills action.The bosonic part of the matrix model action (2.1) reduces in the semi-classical limit for the above 3+1 dimensional backgrounds T ȧ to the following Yang-Mills-type action
S YM = Tr[T α, T β ][T α, T β ] ∼ − M Ω {T ȧ, T ḃ}{T ȧ, T ḃ} . (2.35)
For type II background branes, the transversal matrices contribute an extra term to this action given by
S (K) YM ∼ − M Ω {T i , T j }{T i , T j } = − M Ω m 4 K F 2 K (2.36)
where F 2 K is some discrete number depending on the structure of K.This term will play an important role in stabilizing the vacuum.There is also a mixed term Ω{T ȧ, T j }{T ȧ, T j }, which amounts to a kinetic term for K.That term is expected to suppress possible variations of m K , but will be omitted in the following.
The one-loop action
The 1-loop effective action Γ 1loop is defined via the Gaussian integral around a given matrix configuration T ȧ:
Z 1loop [T ] = 1loop
dT dΨdcdc e iS[T,Ψ,c] = e S[T ]+Γ 1loop [T ] (3.1)
with fermion Ψ and ghost c (for gauge-fixing) contributions integrated out and the bare action (2.1) evaluated on the background under consideration.This path integral can be regularised by a Feynman iε term through the following addition,
S → S + iε Tr α (T α) 2 . (3.2)
Due to the maximal supersymmetry of our matrix model the first three terms of the effective action cancel, resulting in the following non-trivial contribution (dropping higherorder contributions O(✷ −5 ))
Γ 1loop;4 = i 8 Tr ✷ −1 M (V ) α β [Θ α β , •] 4 − 1 2 ✷ −1 M (ψ) α β [Θ α β , •] 4 = 3i 4 Tr V 4 (✷ − iε) 4 (3.3)
where M α β are SO(1, 9) generators acting on vector (V ) and spinor (ψ) representations, the trace is over End(H), and
V 4 = −4tr(δΘ 4 ) + (tr(δΘ 2 )) 2 (3.4) with δΘ = [Θ, .].
Recently, this 4th order 1-loop term has been computed [13,14] for the brane-II configuration (2.30-2.31),observing that the traces are UV finite.On such product space M × K, the various contributions from V 4 split into three parts
V 4 = V M 4 + V K 4 + V M−K 4
with contributions coming from M, or K, or both:
V M 4 = (δΘ ȧḃ δΘ ȧḃ )(δΘ ċ ḋδΘ ċ ḋ) − 4(δΘ ȧḃ δΘ ḃ ċδΘ ċ ḋδΘ ḋ ȧ) , V K 4 = (δΘ ij δΘ ij )(δΘ kl δΘ kl ) − 4(δΘ ij δΘ jk δΘ kl δΘ li ) , V M−K 4 = 2(δΘ ȧḃ δΘ ȧḃ )(δΘ ij δΘ ij ) .(3.5)
The mixed term V M−K 4 is most important 9 for us, as it yields an Einstein-Hilbert-like contribution to the action in terms of the effective metric G µν .The trace can be evaluated in the semi-classical regime using the above geometric quantities, notably the torsion (2.15) which arises from δΘ ∼ i{Θ, .}.This leads to
Γ M−K 1loop;4 = M d 4 x |G| 16πG N R + 1 2 T • T − 2ρ −2 ∂ρ • ∂ρ + 2ρ −1 G −1 N ∂ρ • ∂G N (3.6)
(here the dot-product is w.r.t. the effective metric, e.g.
T • T = T µ T ν G µν ), using the following identity [16, Appendix E] R = − 1 2 T µ σρ T ρ µσ ′ G σσ ′ − 1 2 T µ T ν G µν + 2ρ −2 G µν ∂ µ ρ ∂ ν ρ − 2∇ µ (G) ρ −1 ∂ µ ρ .(3.7)
Here G N plays the role of Newton's constant and is given by
G N = π 3 ρ 2 2c 2 K m 2 K (3.8)
in terms of the scale m K and a constant c K ≫ 1.In addition, the one-loop effective action also contains contributions (from V K 4 ) that are naturally interpreted as vacuum energy.They have the form [14] S
vac = M Ωρ −2 C 1 m 4 K + C 2 1 R 4 + C 3 1 R 8 m 4 K (3.9)
with large but finite constants C i .In the traditional approach to gravity, the vacuum energy contributions would have the form √ G Λ 4 , which amounts to a cosmological constant.The presence of the rigid symplectic volume form Ω in the present framework suggests that the usual cosmological constant problem should not arise here.Moreover, the induced vacuum energy density decreases with the cosmic expansion due to Ωρ −2 ∼ |G|ρ −4 and ρ ∼ a(t).However, this vacuum energy will play a role in determining m K .
Emergent gravity from the one-loop effective action
Now we consider the full one-loop effective action, comprising the bare Yang-Mills matrix model (2.35) and the 1-loop contribution Γ 1loop (3.6):
S eff = S YM + S matter + Γ 1loop . (4.1)
We have also included explicitly a (classical) matter action
S matter = d 4 x |G µν | L matter ,(4.2)
which arises from the fermionic terms of the matrix model, as well as contributions of the non-abelian sector arising from the fuzzy extra dimensions K, depending on the specific background.To understand the equations of motion (eom) for this coupled system, we consider a generic background fluctuation δT ȧ = A ȧ on M 1,3 (2.5), which yields a frame fluctuation around E µ ȧ (2.9):
δE µ ȧ ≡ δ A E µ ȧ = {A ȧ, x µ } .(4.3)
For computational simplicity we first consider the variation in the metric δG µν , in the dilaton δρ and in the KK mass δm K (2.32) as independent 10 , so that we obtain
δS eff = 4 M d 4 xρ M ✷T ȧ δT ȧ − 1 2 M d 4 x |G µν | T (m) µν δG µν − 4 M Ω F 2 K m 3 K δm K + δΓ 1loop (4.4) where T (m)
µν is the standard stress-energy tensor for matter which is given by
T (m) µν = − 2 |G µν | δS matter δG µν = −2 δL matter δG µν + G µν L matter .(4.5)
The variation of the 1-loop term, i.e. δΓ 1loop , is obtained after a cumbersome exercise involving variations of its individual components (see Appendix A); the result (A.23) can be neatly expressed using
ρ = e σ and m K = e λ ,(4.6)
to rewrite the logarithmic derivations.We obtain (including the vacuum energy contributions)
δΓ 1loop = M d 4 x |G| 16πG N R µν − 1 2 G µν R − 1 2 T µ T ν − 1 2 G µν T • T − 2∂ µ σ∂ ν σ − 3G µν ∂σ • ∂σ + 2 2∂ µ σ∂ ν λ − 3G µν ∂σ • ∂λ − 4 ∂ µ λ∂ ν λ − G µν ∂λ • ∂λ + 2 ∂ µ ∂ ν σ − G µν ✷ G σ − 2 ∂ µ ∂ ν λ − G µν ✷ G λ δG µν + M d 4 x |G| 16πG N −2R − T • T + 4∂σ • ∂σ − 8∂σ • ∂λ + 8∂λ • ∂λ − 4✷ G σ + 4✷ G λ δσ + M d 4 x |G| 16πG N 2R + T • T − 4∂σ • ∂σ + 4✷ G σ δλ − 2 M Ωρ −2 C 1 m 4 K + C 2 R 4 + C 3 R 8 m 4 K δσ − M d 4 x ρ 2 16πG N ε νσµκ T κ T ȧ νµ + m −2 K E ȧ µ ∂ ν (m 2 K T κ ) δE ȧσ + 4 M Ωρ −2 C 1 m 4 K − C 3 R 8 m 4 K δλ .
(4.7) 10 The variation in the first two can be written in terms of δE µ ȧ as we will see below, while m K is a priori an independent degree of freedom.
We can further simplify this expression by diagonalizing (most of) the kinetic terms via
σ = σ − λ ,(4.8)
to obtain the following result for δΓ 1loop (4.7):
δΓ 1loop = M d 4 x |G| 16πG N R µν − 1 2 G µν R − 1 2 T µ T ν − 1 2 G µν T • T − 2∂ µ σ∂ ν σ − 3G µν ∂ σ • ∂ σ − 2∂ µ λ∂ ν λ − G µν ∂λ • ∂λ + 2 ∂ µ ∂ ν σ − G µν ✷ G σ δG µν + −2R − T • T + 4∂ σ • ∂ σ + 4∂λ • ∂λ − 4✷ G σ δσ + −8∂ σ • ∂λ + 4✷ G λ δλ − M d 4 x ρ 2 16πG N ε νσµκ T κ T ȧ νµ + m −2 K E ȧ µ ∂ ν (m 2 K T κ ) δE ȧσ − 2 M Ωρ −2 C 1 m 4 K + C 2 R 4 + C 3 R 8 m 4 K δσ + 2 M Ωρ −2 C 1 m 4 K − C 2 R 4 − 3 C 3 R 8 m 4 K δλ .
(4.9)We obtain the eom for m K corresponding to δλ in (4.7) using (2.11) and also including the bare matrix model contribution S YM (4.4) as follows:
R + 1 2 T • T − 2∂σ • ∂σ + 2✷ G σ − 32πG N ρ −2 F 2 K m 4 K + 32πG N ρ −4 C 1 m 4 K − C 3 1 R 8 m 4 K = 0 .
(4.10)This equation determines m K .To be specific, we assume that the vacuum energy contributions given by the last terms with C 1 , C 3 > 0 dominate.Then m 2 K is given as the minimum of the effective potential,
m 8 K ≈ C 3 C 1 1 R 8 .(4.11)
This provides a dynamical stabilization of K through quantum effects; accordingly, we will assume that λ = const from now on, and drop the tilde on σ.Together with (2.11), the above expression for δΓ 1loop (4.7) takes a simpler form:
δΓ 1loop = M Ω ρ 2 16πG N R µν − 1 2 G µν R − 1 2 T µ T ν − 1 2 G µν T • T − 2∂ µ σ∂ ν σ − 3G µν ∂σ • ∂σ + 2 ∂ µ ∂ ν σ − G µν ✷ G σ δG µν − ρ −1 M ε νσµκ T κ T ȧ νµ + E ȧ µ ∂ ν T κ δE ȧσ − 2 R + 1 2 T • T − 2∂σ • ∂σ + 2✷ G σ + 16πG N ρ −4 C 1 m 4 K + C 2 R 4 + C 3 R 8 m 4 K δσ .
(4.12)The variations δG µν and δσ can be expressed as follows (Appendix B):
δσ = 1 2 E ȧσ δE ȧσ ,(4.13
)
δG µν = 2ρ −2 E µ ȧ δE ȧν − G µν E ȧσ δE ȧσ . (4.14)
Plugging these relations into (4.12)while also using the constraint arising from the m K eom (4.10) to eliminate R gives us the following variation of Γ 1loop in terms of the frame11 :
δΓ 1loop = M Ω 8πG N R µλ − 1 2 T µ T λ − 2 ∂ µ σ∂ λ σ + G µλ ∂σ • ∂σ + 2 ∂ µ ∂ λ σ + 1 2 G µλ ✷ G σ − 8πG N ρ −4 G µλ 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K E µ ȧ − 1 2 ρ −1 M G σλ ε νσµκ (T κ T νµ ȧ + E ȧµ ∂ ν T κ ) δE ȧλ . (4
.15)
We can also express the variation of the matter action in terms of the frame as
δS matter = − 1 2 M d 4 x |G µν | T (m) µν δG µν = − 1 2 M Ω ρ 2 T (m) µν 2ρ −2 E µ ȧ δE ȧν + G µν E ȧσ δE ȧσ = − 1 2 M Ω 2T (m) µλ E µ ȧ δE ȧλ − ρ 2 T (m) E ȧ λ δE λ ȧ = − 1 2 M Ω 2T (m) µλ E µ ȧ − G σλ T (m) E σ ȧ δE ȧλ ,(4.16)
where
T (m) = G µν T (m)
µν (4.5) is the trace of the matter stress-energy tensor.This extra trace contribution arises due to the conformal factor ρ 2 in the effective metric, but will drop out in the equations of motion.
Using the above result (4.15) and (4.16), the variation of the full action for the coupled system (4.4) takes the following form
δS eff = M Ω 8πG N R µλ − 1 2 T µ T λ − 2 ∂ µ σ∂ λ σ + G µλ ∂σ • ∂σ + 2 ∂ µ ∂ λ σ + 1 2 G µλ ✷ G σ − 8πG N T (m) µλ − 1 2 G µλ T (m) − 8πG N ρ −4 G µλ 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K E µ ȧ − 1 2 ρ −1 M G σλ ε νσµκ (T κ T νµ ȧ + E ȧµ ∂ ν T κ ) δE ȧλ + 4 M Ω ✷T ȧ δT ȧ . (4.17)
Notice that ρ −1 M ε νσµκ in the third line is indeed a tensor.To make the resulting eom more transparent, we can find
C ȧµ = C νµ E ν ȧ (4.18) such that ✷T ȧ = {C ȧµ , x µ } . (4.19)
This can generically be solved by the ansatz C ȧµ = {B ȧ, x µ }, which leads to
✷ x B ȧ = ✷T ȧ ∼ ρ 2 ✷ G T ȧ , where ✷ x = −{x µ , {x µ , .}} . (4.20)
Such a C ȧµ is not unique, but admits the following "gauge invariance"
C ȧµ → C ȧµ + ∂ µ C ȧ . (4.21)
For example, for the unperturbed background12 M 1,3 we have
C ȧµ = 3 r 2 R 2 sinh(η)η ȧµ (4.22) with B ȧ = 3 r 2 R 2 t ȧ.
More generally, C µν measures the "anharmonicity" of the background, i.e. the deviation from ✷T ȧ = 0. We can then write the variation of the bare YM action in the form
δS YM = 4 M d 4 xρ M ✷T ȧ δT ȧ ∼ 4 M d 4 xρ M {C ȧµ , x µ } δT ȧ = −4 M d 4 xρ M C ȧµ {δT ȧ, x µ } = −4 M d 4 xρ M C ȧµ δE ȧµ . (4.23)
This is consistent with the ambiguity (4.21) due to the divergence constraint (2.13).That ambiguity will eventually be fixed in Appendix C.
Assuming for the moment that the fluctuations of the frame are unconstrained, this leads to the eom
R µλ − 2 ∂ µ σ∂ λ σ + G µλ ∂σ • ∂σ + 2 ∂ µ ∂ λ σ + 1 2 G µλ ✷ G σ − 1 2 T µ T λ − 8πG N ρ −4 G µλ 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K E µ ȧ − 1 2 ρ −1 M G σλ ε νσµκ (T κ T νµ ȧ + E ȧµ ∂ ν T κ ) = 8πG N T (m) µλ − 1 2 G µλ T (m) + 4C µλ E µ ȧ . (4.24)
This can be written without the frame as follows:
R µλ = 8πG N T (m) µλ − 1 2 G µλ T (m) + ρ −4 G µλ 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K + 4C µλ + 2 ∂ µ σ∂ λ σ+G µλ ∂σ • ∂σ − 2 ∂ µ ∂ λ σ+ 1 2 G µλ ✷ G σ + 1 2 T µ T λ + 1 2 ρ −1 M G σλ ε νσρκ T κ T νρµ +γ µρ ∂ ν T κ (4.25)
which in the absence of totally antisymmetric torsion T (AS) = 0 simplify as
R µλ = 8πG N T (m) µλ − 1 2 G µλ T (m) + ρ −4 G µλ 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K + 4C µλ + 2 ∂ µ σ∂ λ σ + G µλ ∂σ • ∂σ − 2 ∂ µ ∂ λ σ + 1 2 G µλ ✷ G σ . (4
.26) In particular, this implies the trace relation
R = 8πG N − T (m) + 4ρ −4 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K + 4C + 10∂σ • ∂σ − 6✷ G σ (4.27)
where C = G µλ C µλ .Combining these, we obtain the modified Einstein equations
R µλ − 1 2 G µλ R = 8πG N T (m) µλ − 1 ρ 4 G µλ 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3C 3 R 8 m 4 K + 4(C µλ − 1 2 G µλ C) + 2 ∂ µ σ∂ λ σ − ∂ µ ∂ λ σ + G µλ (✷ G σ − 3 2 ∂σ • ∂σ) . (4.28)
This may need to be amended by the axionic field T µ as above.We note that the anharmonicity tensor C µλ , which arises from the Yang-Mills term via (4.19), plays the role of a source term in the Einstein equation.However, remember that C µλ is only determined up to a total divergence E ȧ λ ∂ µ C ȧ (4.21), which reflects the divergence constraint of the frame.Thus the variations δE ȧµ are not independent, so that the above equations only hold up to precisely this ambiguity.This can be indicated by writing them as
R µλ − 1 2 G µλ R = 8πG N T (m) µλ − ρ −4 G µλ 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K + 4 C µλ + E ȧ λ ∂ µ C ȧ − 1 2 G µλ (C + ρ −2 E ȧµ ∂ µ C ȧ) + 2 ∂ µ σ∂ λ σ − ∂ µ ∂ λ σ + G µλ (✷ G σ − 3 2 ∂σ • ∂σ) (4.29)
for some undetermined C ȧ, and similarly in the version including the axionic field T µ .This ambiguity will be fixed in Appendix C through the conservation of the Einstein tensor.
In the above computations, it should be kept in mind that the geometric quantities generically contain non-vanishing higher spin components, which may not be fully accounted for in the above form.Nevertheless, the above equations should be satisfied at least in the weak gravity regime for the classical, dominant components of the geometry.
Cosmological FLRW background.Now consider the undeformed FLRW background M 1,3 .Then the anharmonicity tensor C µλ arising from the classical YM action is given explicitly by
C µλ = 3 r 2 R 2 sinh(η)η ȧµ E ȧ λ = 3 r 2 R 2 η µλ = 3 r 2 R 2 sinh(η) G µλ (4.30)
where G µν is the effective metric (2.25) on M 1,3 .This acts like an additional vacuum energy contribution to the gravitational equations.At early times cosh(η) = O(1), the vacuum energy contributions determined by C i which scale like ρ −4 G µν dominate the classical YM contribution C µν ∼ 1/r 2 R 2 η µν for sufficiently large 13 C i .We assume for simplicity that the contribution from F 2 K is sub-leading and can be dropped.Then both sides of (4.28) behave like ρ −2 G µν + ρ −4 τ µ τ ν (noting (3.8) and (2.26), where τ is the timelike FLRW vector field [19]); moreover, the fuzzy extra dimensions K are stabilized via (4.11).All this supports the consistency of the present background M 1,3 × K at early times.This is confirmed in a more careful study of the 1-loop equations of motion for this background in [20].
Late-time regime.At late times η ≫ 1, the vacuum energy described by C i decreases with the cosmic expansion as ρ −4 ∼ a(t) −4 .Hence the vacuum energy contribution to the curvature becomes negligible, so that no cosmological constant problem arises.On the other hand, the C µλ tensor from the undeformed background M 1,3 clearly has a significant impact on the 1-loop equation of motion, so that the background is no longer consistent.But this is easily understood and fixed: the undeformed background T ȧ is a solution of the classical IKKT model only in the presence of an extra mass term in the action.That mass term was put in by hand to stabilize M 1,3 at the classical level; it should be removed in the quantum theory.Upon dropping this mass term, that background is modified to the following classical solution
T ȧ ∼ α(η)t ȧ (4.31)
with α(η) ∼ e η , as shown in [20].This leads to the effective metric Gµν = cosh 3 (η)η µν , which describes a somewhat modified k = −1 FLRW geometry rather similar to M 1,3 , with an accelerated expansion and cosmic scale parameter a(t) ∼ 5 2 t.Then the above background tensor vanishes Cµν = 0 (4.32) since ✷ T ȧ = 0.In the presence of local perturbations, some anharmonicity C µν = 0 will arise, which is related to the geometry in a non-local way that remains to be understood in detail.However, note that C µν is determined via (4.19) as a "first derivative" (in a non-local sense) of the background T ȧ, just like the frame E ȧµ , and is therefore soft compared with the curvature.This reflects the fact that the Einstein-Hilbert action has two more derivatives than the bare matrix-model action which determines C µν .Moreover, C µν is expected to vanish in vacuum in the linearized regime, where perturbations are harmonic (hence C µν = 0) and Ricci-flat [21].Therefore C µν is expected to be subleading compared with the standard GR contributions, at least at shorter scales.On the other hand, the scaling argument does not apply for long scales, where any non-vanishing C µν may have significant impact.A more careful examination of the cosmological evolution at one loop [20] suggests that the classical equations of motion indeed dominate over the induced one-loop effects, leading to a picture that is rather different from GR and less sensitive to the detailed matter content 14 .
All this suggests that the present framework leads to a physically reasonable emergent gravity theory, which is close to general relativity (extended by dilatonic and axionic contributions 15 ) at shorter scales, but deviates significantly from GR on cosmic scales.
Discussion and conclusion
The main result of this paper is an equation for the geometry of brane solutions of the IKKT matrix model, based on the one-loop effective action obtained in [13,14].This is non-trivial because the fundamental degrees of freedom of the matrix model are given by (fluctuations of) the matrix background, while the frame and metric are derived objects, given by certain derivatives of the matrix fluctuations.That is not surprising in a Yang-Mills theory, but it makes it hard to cast the equations into a recognizable form that can be compared with general relativity.We managed to find a transparent form for such a modified Einstein equation, in terms of a novel "anharmonicity" tensor C µν which measures the deviation from a harmonic background.This result is clearly a useful step towards understanding the physics of the gravity theory which emerges from the matrix model.In particular, it provides strong evidence that the resulting gravity theory behaves similarly to GR in some regime, which is essential for its physical viability.However, we have not yet found a useful way to describe the effect of the new tensor C µν explicitly, which is related to the metric geometry in a non-local way.This is perhaps the most pressing task to be addressed in follow-up work.
There are many other open questions that need to be addressed in future work.In particular, it turns out that perturbations (4.3) of the present type of covariant quantum spaces M 1,3 generically involve higher-spin (hs)-valued components, which mirror the geometric ones.This implies that local perturbations of the torsion are mirrored by hsvalued components, which have been dropped in this paper.These carry essentially the same information and are not expected to significantly change the above results, except possibly in the extreme IR regime 16 .That issue needs to be addressed in detail elsewhere.
Finally, we recall that the fuzzy extra dimensions K lead to an interesting nonabelian gauge theory in the present framework, through spontaneous breaking of some internal gauge group U(n) [22].This can lead to an interesting low-energy gauge theory with (approximate) fermionic zero modes governed by the effective metric discussed in this paper.
while the other term of (A.7) can be computed by noting the following contraction,
δΓ ρ ρµ = 1 2 G ρκ ∇ µ δG ρκ , (A.10) to obtain G µν ∇ ν δΓ ρ ρµ = − 1 2 G ρκ G δG ρκ . (A.11)
Taken together, these relations (A.7-A.11) gives us the required integral, which we partially integrate to obtain (up to some boundary term)
I 1 = c 2 K 8π 4 M d 4 x |G µν |K µν δG µν with K µν = G µν G m 2 K ρ 2 − ∂ µ ∂ ν m 2 K ρ 2 .
(A.12) A straightforward computation then gives us the following bulky expression for this integrand:
K µν δG µν = − 2 ρ 2 (∂ µ m K ∂ ν m K − G µν ∂m K • ∂m K ) + 8m K ρ 3 (∂ µ m K ∂ ν ρ − G µν ∂m K • ∂ρ) − 6m 2 K ρ 4 (∂ µ ρ ∂ ν ρ − G µν ∂ρ • ∂ρ) − 2m K ρ 2 (∂ µ ∂ ν m K − G µν G m K ) + 2m 2 K ρ 3 (∂ µ ∂ ν ρ − G µν G ρ) δG µν .
(A.13) Plugging these results (A.12-A.13)back into (A.4) we obtain
δS R = M d 4 x |G| 16πG N (R µν − 1 2 G µν R) − 2 m 2 K (∂ µ m K ∂ ν m K − G µν ∂m K • ∂m K ) + 8 m K ρ (∂ µ m K ∂ ν ρ − G µν ∂m K • ∂ρ) − 6 ρ 2 (∂ µ ρ ∂ ν ρ − G µν ∂ρ • ∂ρ) − 2 m K (∂ µ ∂ ν m K − G µν G m K ) + 2 ρ (∂ µ ∂ ν ρ − G µν G ρ) δG µν − RG −1 N δG N . (A.14)
Variation of S T .First of all, a straightforward computation involving (A.3) yields
δS T = M d 4 x |G| 16πG N 1 2 T µ T ν − 1 2 G µν T •T δG µν − 1 2 T •T G −1 N δG N +G µν T µ δT ν . (A.15)
Furthermore, the term involving δT ν simplifies as follows (see [16, Appendix E]):
I 2 = M d 4 x |G| 16πG N G µν T µ δT ν , = 1 2 M d 4 x |G| 16πG N G λρ T λ |G µν | −1 ρ 2 G ρκ ε νσµκ δT νσµ + ε νσµκ T νσµ δG ρκ + 2 ρ δρ + 1 2 G µν δG µν 2T ρ = 1 2 M d 4 x |G| 16πG N − 2 T µ T ν − 1 2 G µν T • T δG µν + 4 ρ T • T δρ + c 2 K 16π 4 M d 4 x m 2 K ε νσµκ T κ δT νσµ , (A.16)
where in the last line we have employed the following definition of T ρ which is equivalent to (2.19)
T ρ = 1 2 |G µν | −1 ρ 2 G ρκ ε νσµκ T νσµ . (A.17)
The last part of this integral can be computed as follows:
I 3 = c 2 K 16π 4 M d 4 x m 2 K ε νσµκ T κ δT νσµ = c 2 K 16π 4 M d 4 x m 2 K T κ ε νσµκ T ȧ νσ δE ȧµ + 2E ȧµ ∂ ν δE ȧ σ = c 2 K 16π 4 M d 4 x m 2 K T κ ε νσµκ T ȧ νσ δE ȧµ − c 2 K 16π 4 M d 4 x ε νσµκ 2E ȧ µ ∂ ν (m 2 K T κ ) + m 2 K T κ T ȧ νµ δE ȧσ = − c 2 K 8π 4 M d 4 x ε νσµκ m 2 K T κ T ȧ νµ + E ȧ µ ∂ ν (m 2 K T κ ) δE ȧσ (A.18)
where we have used the definition of the torsion (2.15) and (2.17) in the second step and integration by parts in the third one.Putting together (A.15), (A.16) and (A.18) we obtain
δS T = M d 4 x |G| 16πG N − 1 2 T µ T ν − 1 2 G µν T • T δG µν − 1 2 T • T G −1 N δG N − M d 4 x ρ 2 16πG N ε νσµκ T κ T ȧ νµ + m −2 K E ȧ µ ∂ ν (m 2 K T κ ) δE ȧσ . (A.19)
Variation of S ρ and S G N .We can compute the variation of S ρ as follows,
δS ρ = −2 M d 4 x |G| 16πG N ρ −2 ∂ µ ρ∂ ν ρ − 1 2 G µν ∂ρ • ∂ρ δG µν − ρ −2 ∂ρ • ∂ρ G −1 N δG N + 2ρ −1 δρ + 2ρ −2 ∂ρ • ∂δρ = −2 M d 4 x |G| 16πG N ρ −2 ∂ µ ρ∂ ν ρ − 1 2 G µν ∂ρ • ∂ρ δG µν − ρ −2 ∂ρ • ∂ρ G −1 N δG N + 2ρ −1 δρ − 2 2 ρ 2 m K ∂ρ • ∂m K − 4 ρ 3 ∂ρ • ∂ρ + ρ −2 ✷ G ρ δρ = −2 M d 4 x |G| 16πG N 1 ρ 2 ∂ µ ρ∂ ν ρ − 1 2 G µν ∂ρ • ∂ρ δG µν + 2 ρ 2 m K (∂ρ • ∂ρ)δm K + 2 ρ 2 2 ρ ∂ρ • ∂ρ − 2 m K ∂ρ • ∂m K − G ρ δρ , (A.20)
using (A.3) in the first and partial integration in the second line.Next, we express S G N using (3.8):
S G N = 4 M d 4 x |G| 16πG N 1 ρ 2 ∂ρ • ∂ρ − 1 ρm K ∂ρ • ∂m K . (A.21)
We then compute the variation of this S G N using a partial integration technique as before:
δS G N = 4 M d 4 x |G| 16πG N − 1 2 G µν δG µν + G −1 N δG N 1 ρ 2 ∂ρ • ∂ρ − 1 ρm K ∂ρ • ∂m K − 2 ρ 3 (∂ρ • ∂ρ)δρ + 1 ρ 2 ∂ µ ρ∂ ν ρδG µν + 2 ρ 2 ∂ρ • ∂δρ + 1 ρm K ∂ρ • ∂m K δρ ρ + δm K m K − 1 ρm K ∂ µ ρ∂ ν m K δG µν − 1 ρm K ∂δρ • ∂m K + ∂ρ • ∂δm K = 4 M d 4 x |G| 16πG N − 1 2 G µν δG µν + G −1 N δG N 1 ρ 2 ∂ρ • ∂ρ − 1 ρm K ∂ρ • ∂m K − 2 ρ 3 (∂ρ • ∂ρ)δρ + 1 ρ 2 ∂ µ ρ∂ ν ρδG µν − 2 ρ 2 ∂ρ • 2 m K ∂m K − 4 ρ ∂ρ δρ + 1 ρm K ∂ρ • ∂m K δρ ρ + δm K m K − 2 ρ 2 ✷ G ρ δρ − 1 ρm K ∂ µ ρ∂ ν m K δG µν + 1 ρm K ∂m K • 1 m K ∂m K − 3 ρ ∂ρ δρ + 1 ρm K ∂ρ • 1 m K ∂m K − 3 ρ ∂ρ δm K + 1 ρm K ✷ G m K δρ + ✷ G ρ δm K = 4 M d 4 x |G| 16πG N 1 ρ 2 ∂ µ ρ∂ ν ρ − 1 2 G µν ∂ρ • ∂ρ δG µν − 1 ρm K ∂ µ ρ∂ ν m K − 1 2 G µν ∂ρ • ∂m K δG µν + 4 ρ 3 ∂ρ • ∂ρ − 4 ρ 2 m K ∂ρ • ∂m K + 1 ρm 2 K ∂m K • ∂m K − 2 ρ 2 ✷ G ρ + 1 ρm K ✷ G m K δρ − 1 ρ 2 m K ∂ρ • ∂ρ − 1 ρm K ✷ G ρ δm K . (A.22)
In this way we obtain the variation of the 1-loop term Γ 1loop (A.1) after combining the variations of S R (A.14), S T (A. 19), S ρ (A.20) and S G N (A.22) that reads This allows to express the dilaton ρ in terms of the frame using (2.11) as
δΓ 1loop = M d 4 x |G| 16πG N R µν − 1 2 G µν R − 1 2 T µ T ν − 1 2 G µν T • T − 1 ρ 2 4∂ µ ρ∂ ν ρ − 5G µν ∂ρ • ∂ρ + 1 ρm K 4∂ µ ρ∂ ν m K − 6G µν ∂ρ • ∂m K − 2 m 2 K ∂ µ m K ∂ ν m K − G µν ∂m K • ∂m K − 2 m K ∂ µ ∂ ν m K − G µν ✷ G m K + 2 ρ ∂ µ ∂ ν ρ − G µν ✷ G ρ δG µν + M d 4 x |G| 16πG N −2R − T • T + 8 ρ 2 ∂ρ • ∂ρ − 8 ρm K ∂ρ • ∂m K + 4 m 2 K ∂m K • ∂m K − 4 ρ ✷ G ρ + 4 m K ✷ G m K ρ −1 δρ + M d 4 x |G| 16πG N 2R + T • T − 8 ρ 2 ∂ρ • ∂ρ + 4 ρ ✷ G ρ m −1 K δm K − M d 4 x ρ 2 16πG N ε νσµκ T κ T ȧ νµ + m −2 K E ȧ µ ∂ ν (m 2 K T κ ) δE ȧσ .ρ 2 = ρ M |E ȧµ | , (B.2)
whose variation can then be obtained by noting that ρ M is rigid:
δσ := ρ −1 δρ = 1 2ρ 2 δ(ρ 2 ) = 1 2ρ 2 δ ρ M |E ȧµ | = − 1 2ρ 2 ρ M |E ȧµ | 2 δ|E ȧµ | = − 1 2ρ 2 ρ M |E ȧµ | 2 |E ȧµ |E ȧσ δE ȧσ = − 1 2 E ȧσ δE ȧσ . (B.3)
With this result in hand, we can compute the variation of the inverse metric G µν (2.7) while also using (2.8) and symmetry of indices as follows:
δG µν = δ ρ −2 γ µν = δ ρ −2 E µ ȧ E ȧν = − 2 ρ 3 γ µν δρ + 2 ρ 2 E µ ȧ δE ȧν = − 2 ρ 2 γ
C Divergence constraint
Taking the divergence ∇ µ of (4.29) and using the conservation of the Einstein tensor and of the energy-momentum tensor of matter, we obtain
0 = 32π∇ µ G N C µλ + E ȧ λ ∂ µ C ȧ − 1 2 G µλ (C + ρ −2 E ȧµ ∂ µ C ȧ) + 2✷ G σ∂ λ σ − 2∂ λ (∂σ • ∂σ)
(C.1) dropping the vacuum energy contributions for simplicity, which is justified at late times.The axionic vector field T µ is dropped for simplicity.This constraint can be used to fix the remaining ambiguity in C ȧν → C ȧν + ∂ ν C ȧ, which determines precisely the 4 degrees of freedom in C ȧ.In that sense, the divergence constraint of the Einstein equations allows us to uniquely determine the anharmonicity tensor C µν which arises from the Yang-Mills background via (4.19).Therefore our modified Einstein equations uniquely determine the geometry of space-time for given matter, dilaton, and axionic field T µ .
D Scalar components
There are two equations for the scalar components, one from (4.27):
R = 8πG N − T (m) + 4ρ −4 2ρ 2 F 2 K m 4 K − C 1 m 4 K + C 2 R 4 + 3 C 3 R 8 m 4 K + 4C + 10∂σ • ∂σ − 6✷ G σ (D.1)
and one from the eom for λ (4.10)
R + 1 2 T • T − 2∂σ • ∂σ + 2✷ G σ − 32πG N ρ −2 F 2 K m 4 K + 32πG N ρ −4 C 1 m 4 K − C 3 1 R 8 m 4 K = 0 . (D.2)
We can eliminate the Ricci scalar from these equations to obtain the following relation among various non-geometric quantities
1 2 T •T +8∂σ•∂σ−4✷ G σ−8πG N T (m) +32πG N ρ −4 ρ 2 F 2 K m 4 K + C 2 R 4 + 2 C 3 R 8 m 4 K + 4C = 0 . (D.
3) The significance of this equation is not clear.
(a) gauge invariance, i.e. the model is invariant under the transformation T α → U −1 T αU , (b) a global SO(1, 9) symmetry acting on dotted indices with invariant tensor η α β , and (c) maximal supersymmetry.
B
Expressing δG µν and δσ in terms of δE ȧµ First of all, we can relate the determinants of effective metric G µν and the frame E ȧµ using the relations (2.8) and (2.7), |G µν | = ρ 4 |E ȧµ | .(B.1)
From now on g 2 is absorbed in the background and hence in G µν .
Notice here that the dotted/undotted labels are raised resp. lowered with η ȧ ḃ/γ µν resp. η ȧ ḃ/γ µν .
In fact, the Jacobi identity for the torsion is a simple consequence of T ȧ being exact, i.e. dT ȧ = 0.
Strictly speaking this is a solution of the classical (!) eom in the presence of a mass term, cf.[17]. That issue will be addressed below at the one-loop level.
The local stabilizer SO(3) at each point of M 1,3 acts non-trivially on the S 2 -fiber.
Here µ 2 Λ refers to the tower of discrete KK modes, while m 2 K is some overall scale associated with the compact K.
Note that in all these computations, the frame and all derived quantities are strictly speaking higherspin valued. We will neglect such components in the present paper, lacking an appropriate formalism to treat these components.
We have adjusted some indices with effective/auxiliary metric while using (2.7).
This follows from the relations {t ȧ, x µ } = sinh(η)η ȧµ and ✷t ȧ = 3 R 2 t ȧ and {sinh(η), x µ } = r 2 t µ on M 1,3 . Here r is a scale parameter fixed by the underlying representation of so(4, 2), see[17].
Note that C i are typically very large sums of structure constants associated to K, cf.[14].
At the classical level, matter does not act as a source for the curvature in the matrix model.
Note that the dilaton and axion are subject to constraints in the present framework[16], and will behave differently from more standard extensions of GR.
See[20] for an analysis of cosmological solutions including these hs components.
AcknowledgementsKK is grateful to the Erwin Schrödinger Institute at Vienna for supporting this work through a Junior Research Fellowship in 2023.The work of HS is supported by the Austrian Science Fund (FWF) grants P32086 and P36479.A Variation of Γ 1loopTo compute the variation of the 1-loop term Γ 1loop(3.6)we first decompose it into following four parts:where the different components of the action are as follows:In the following calculations, we will be working in Riemann normal coordinates where the first derivatives of the metric vanishes.This means that we will routinely interchange partial derivatives with covariant derivatives, since they differ by Christoffel symbols that are also vanishing.Variation of S R .Using R = G µν R µν and the well-known variation of the determinant:we can express the variation of S R in (A.1) as follows:Here we have made use of the following result:The non-trivial term here is the last one involving δR µν , i.e.A well-known geometrical result gives us δR µν in terms of the variation of Christoffel symbol:We also have the following result in the normal coordinates:Equipped with this result, we can now compute the first term of (A.7) to getG µν ✷ G δG µν , (A.9)
A Large N reduced model as superstring. N Ishibashi, H Kawai, Y Kitazawa, A Tsuchiya, 10.1016/S0550-3213(97)00290-3arXiv:hep-th/9612115Nucl. Phys. B. 4981997
. H Aoki, S Iso, H Kawai, Y Kitazawa, T Tada, 10.1143/PTP.99.713arXiv:hep-th/9802085Prog. Theor. Phys. 991998
Noncommutative geometry and matrix theory: Compactification on tori. A Connes, M R Douglas, A S Schwarz, 10.1088/1126-6708/1998/02/003arXiv:hep-th/9711162JHEP. 0231998
Schwarzschild black holes in various dimensions from matrix theory. I R Klebanov, L Susskind, 10.1016/S0370-2693(97)01318-XarXiv:hep-th/9709108Phys. Lett. B. 4161998
Noncommutative Yang-Mills in IIB matrix model. H Aoki, N Ishibashi, S Iso, H Kawai, Y Kitazawa, T Tada, 10.1016/S0550-3213(99)00633-1arXiv:hep-th/9908141Nucl. Phys. B. 5652000
Quantum field theory on noncommutative spaces. R J Szabo, 10.1016/S0370-1573(03)00059-0arXiv:hep-th/0109162Phys. Rept. 3782003
Noncommutative field theory. M R Douglas, N A Nekrasov, 10.1103/RevModPhys.73.977arXiv:hep-th/0106048Rev. Mod. Phys. 732001
Noncommutative field theories and gravity. V O Rivelles, 10.1016/S0370-2693(03)00271-5arXiv:hep-th/0212262Phys. Lett. B. 5582003
On The Correspondence Between Noncommuative Field Theory And Gravity. H S Yang, 10.1142/S0217732307023675arXiv:hep-th/0612231Mod. Phys. Lett. A. 222007
R J Szabo, 10.1088/0264-9381/23/22/R01arXiv:hep-th/0606233Symmetry, gravity and noncommutativity. 200623
On the quantum structure of space-time, gravity, and higher spin in matrix models. H C Steinacker, 10.1088/1361-6382/ab857farXiv:1911.03162Class. Quant. Grav. 37112020. 113001
A note on graviton exchange in the emergent gravity scenario. H Kawai, K Kawana, K Sakai, 10.1093/ptep/ptx036arXiv:1610.09844PTEP. 201742017
Gravity as a quantum effect on quantum space-time. H C Steinacker, 10.1016/j.physletb.2022.136946arXiv:2110.03936Phys. Lett. B. 8271369462022
One-loop effective action and emergent gravity on quantum spaces in the IKKT matrix model. H C Steinacker, 10.1007/JHEP05(2023)129arXiv:2303.08012JHEP. 051292023
Higher-spin gravity and torsion on quantized space-time in matrix models. H C Steinacker, 10.1007/JHEP04(2020)111arXiv:2002.02742JHEP. 041112020hep-th
Exploring the gravity sector of emergent higher-spin gravity: effective action and a solution. S Fredenhagen, H C Steinacker, 10.1007/JHEP05(2021)183arXiv:2101.07297JHEP. 051832021
Covariant cosmological quantum space-time, higher-spin and gravity in the IKKT matrix model. M Sperling, H C Steinacker, 10.1007/JHEP07(2019)010arXiv:1901.03522JHEP. 07102019
On the propagation across the big bounce in an open quantum FLRW cosmology. E Battista, H C Steinacker, ; E Battista, H C Steinacker, 10.1140/epjc/s10052-022-10874-0arXiv:2207.01295arXiv:2212.08611Eur. Phys. J. C. 8210460212022. 2023Phys. Rev. D
Higher-spin gravity and torsion on quantized space-time in matrix models. H C Steinacker, 10.1007/JHEP04(2020)111arXiv:2002.02742JHEP. 041112020
One-loop effective action of the IKKT model for cosmological backgrounds. E Battista, H C Steinacker, arXiv:2310.11126
Emergent gravity on covariant quantum spaces in the IKKT model. H C Steinacker, 10.1007/JHEP12(2016)156arXiv:1606.00769JHEP. 121562016
Intersecting branes and a standard model realization in matrix models. A Chatzistavrakidis, H Steinacker, G Zoupanos, 10.1007/JHEP09(2011)115arXiv:1107.0265JHEP. 091152011
| [
-0.08457304537296295,
-0.13934320211410522,
-0.006762553937733173,
0.02560099959373474,
-0.05241214111447334,
0.09014997631311417,
-0.06587579846382141,
0.07460956275463104,
0.12112122774124146,
-0.06497809290885925,
0.014816906303167343,
-0.069061279296875,
-0.19328373670578003,
0.0147568... |
Commutativity and Disentanglement from the Manifold Perspective
17 Dec 2023
Frank Qiu frankqiu@berkeley.edu
Commutativity and Disentanglement from the Manifold Perspective
17 Dec 2023E3AF56C0D1B4BBF3FCAD44D403385045arXiv:2210.07857v4[stat.ML]DisentanglementManifold LearningCommutativity
In this paper, we interpret disentanglement as the discovery of local charts of the data manifold and trace how this definition naturally leads to an equivalent condition for disentanglement: commutativity between factors of variation.We study the impact of this manifold framework to two classes of problems: learning matrix exponential operators and compressing data-generating models.In each problem, the manifold perspective yields interesting results about the feasibility and fruitful approaches their solutions.We also link our manifold framework to two other common disentanglement paradigms: group theoretic and probabilistic approaches to disentanglement.In each case, we show how these frameworks can be merged with our manifold perspective.Importantly, we recover commutativity as a central property in both alternative frameworks, further highlighting its importance in disentanglement.
Introduction
Disentanglement has many definitions but is broadly understood as the discovery of semantically meaningful factors that describe a dataset (Bengio (2013); Bengio et al. (2014); Higgins et al. (2018); Burgess et al. (2018)).On a seemingly unrelated note, there have been attempts to understand real-world data from the perspective of manifolds (Roweis and Saul (2000); Zheng and Xue (2009); Tenenbaum et al. (2000); Chen et al. (2018)); a prime example is the manifold hypothesis (Fefferman et al. (2016)), which posits that high-dimensional data from the real world has a low-dimensional description.We argue that these two topics touch on the same idea, and there is a natural interpretation of disentanglement as learning the data manifold's local charts.Indeed, this perspective has already been advanced several times (Brahma et al. (2016); Zhou et al. (2021); Reed et al. (2014)), linking manifold learning and disentanglement as the same task.In this paper, we give precise definitions to the informal concepts of disentanglement and factors of variation under this manifold framework, and we proceed to explore the implications of these definitions.Importantly, we show that commutativity between factors of variation is central to disentanglement.We demonstrate the utility of this framework applied to two problems -the learning of matrix exponential operators and the distillation of data-generating models.Finally, we conclude with a discussion of how our manifold framework relates to two other common disentanglement frameworks: group theoretic and probabilistic disentanglement.
Disentanglement from the Manifold Perspective
Most approaches to disentanglement involve learning a data-generating function whose arguments correspond to semantically meaningful variations in the data.That is, given a Qiu dataset P , one learns a generative function f such that:
∀p ∈ P, ∃x i ∈ X i s.t. f (x 1 , • • • , x n ) ≈ p
and each x i captures something meaningful about the data.The above requirement might be unrealistic for real datasets where the data can vary in many distinct ways.For example, consider a collection of portraits of multiple people, taken under varying lighting conditions and poses.It would difficult to learn a global function f (x 1 , x 2 ) where x 1 controls lighting and x 2 controls pose, since there is so much variability in facial features between subjects.Instead, it might be more realistic to learn a local function f p that controls lighting and pose for each person p.
The above process of breaking up the generative function f can be further extended: for many or all data points p i we learn a local generative function
f p i (x 1 , • • • , x n ) such that f p i (x 1 , • • • , x n ) ≈ p ′
for all points p ′ close to p i .Hence, we pass from the strong requirement of a global function f to the weaker requirement of a collection of local functions f p i (x 1 , • • • , x n ).Intuitively, we can interpret the latent variables x i as the intrinsic coordinates of the local patches they describe, and we shall shortly formalize this notion.
Defining Disentanglement
The manifold hypothesis posits that high-dimensional data drawn from the real world lies on or near a low-dimensional manifold.More informally, high-dimensional data has a lowdimensional description.This description is given by the manifold's local charts, which map patches of the manifold to Euclidean coordinates.Returning to our disentangling function f (x 1 , • • • , x n ), let us assume the latent variables x i are all real numbers.As previously discussed, we can interpret these disentangled latent variables as the data manifold's coordinates.
Definition 1.The data lies on or near a smooth manifold M , and the function f (x 1 , • • • , x n ) disentangles the data if (locally) its latent variables x i correspond to the coordinates of some local chart of M .We call f (x 1 , • • • , x n ) a disentangling function.
In practice, a learned generative map f might not be a chart map itself but instead becomes a local chart after suitable restriction.For example, consider the positions of a clock's hour hand, which can be identified with the unit circle S 1 .We have the natural covering map π:
π : R → S 1 ; t → e 2πit
This covering map describes the full set of hour hand positions but is not injective and hence cannot be a local chart.However, if we restrict π to any suitably small interval I, then π| I is a local chart.Importantly, the latent variable of π| I coincides with the coordinate of a local chart.Note that our definition of disentanglement is a local one, and for the remainder of this paper we shall primarily concern ourselves with local properties of a disentangling function.
Defining Factors of Variation
Another prevalent concept in the disentanglement literature is that of a factor of variation.While its precise definition varies, there are a few properties that are generally agreed upon (Bengio et al. (2014); Reed et al. (2014)).Firstly, a factor of variation encodes a single semantically meaningful dimension on which the data can vary, and manipulating that dimension generates other valid data points.Going back the portraits example, the lighting condition of each portrait can be considered a single factor of variation.For a given portrait, we can slightly brighten or dim the lighting, and doing so would generate a new valid portrait.Secondly, a factor of variation has an implicit consistency condition, where sequential variations must be consistent with their total variation.Given a portrait p 0 , suppose we dimmed its lighting condition by 10 lumens to generate a new portrait p 1 , and then we dimmed the lighting condition of portrait p 1 by 10 lumens to generate another portrait p 2 .If we dimmed the lighting of the original p 0 by 20 lumens, this should generate the same portrait p 2 .Finally, different data points can be described by different factors of variation, and if a data point p is unaffected by a change in a factor's value then it isn't described by that factor.In summary, we have the following basic properties of a factor of variation:
1. Feasibility: At data point p ∈ M , varying the factor F by small enough t results in another data point:
F (t, p) ∈ M
2. Consistency: At data point p, varying factor F by t + s gives the same result as sequentially varying by t and then s:
F (t + s, p) = F (s, F (t, p))
3. Non-degeneracy: If p is described by the factor F , then varying the factor F causes a change in the data.That is, there is no interval I containing 0 such that F (t, p) is constant for t ∈ I.
The first two conditions characterize a factor of variation as a flow function, which is a function F : D → M , where D ⊆ R × P , that satisfies the first two conditions.Intuitively, at each data point p a factor's flow function describes a path through the dataset resulting from varying that factor.For example, given a portrait p, continuously changing its lighting condition generates a path of through the portrait dataset where each point on that path is a portrait p t that differs from p in only its lighting condition.If we further assume that a factor's flow be smooth with respect to the data manifold's topology, we can formalize a factor of variation in the language of smooth manifolds: Definition 2. A factor of variation θ is a collection of smooth non-degenerate local flows on the data manifold M .If p ∈ M is described by the factor θ, there is a smooth non-degenerate local flow θ p on a neighborhood of p called a local factor of variation.
Note the locality condition in our definition.In a heterogeneous dataset, certain factors of variation might not be universal across the data.For example, not all mammals have tails, and tail length would be a factor of variation unique to a subset of mammals.The locality condition allows our definition to flexibly cover such cases.
Discrete Factors, parameterization, and Smoothness
We assumed that each factor of variation is continuous, but in practice there are many examples of discrete factors.The subject's identity in our portrait dataset is one such example, where we have portraits of different people.However, discrete factors of variation can still be subsumed in our manifold framework.Continuous factors describe small local changes, and we will shortly establish that continuous factors correspond to variations in the data manifold's coordinates.On the other hand, discrete factors describe jumps in the data manifold.For example, in our portrait dataset, the collection of portraits of a single person constitute a cluster, and varying continuous factors like lighting conditions or camera angles keeps us within that cluster.However, varying the subject identity makes us jump from cluster to cluster, and in the language of manifolds we can imagine discrete factors as describing jumps between disjoint neighborhoods or even components of the data manifold.Hence, discrete factors describe a fundamentally different change in the data, and in keeping with our emphasis on local coordinates we shall consider only continuous factors.
We also assumed that each factor of variation was parametrized by a real number.Notably, in the group theory definition of disentanglement, a factor of variation may take values in some some group other than the reals.However, in Section 6 we shall see that for a large class of naturally-occurring groups, group-valued factors can be equivalently described by a collection of real-valued factors.
Finally, we argue that our smoothness assumption is a mild one.Often, factors correspond to variations that are smooth with respect to the ambient Euclidean space the data lives in.If the data manifold M is an immersed manifold of the ambient Euclidean space, then such factors are also smooth with respect to the smooth topology on M because immersions are local embeddings.Since our low dimensional data manifold M is assumed to live in a much higher dimensional Euclidean space, it seems reasonable to assume that M is an immersed submanifold.Indeed, stronger results like the Whitney embedding theorems corroborate this.
Factors of Variation and Disentanglement
Having defined both disentanglement and factors of variation, we now discuss their relation within the smooth manifold framework.Recall that a disentangling function f (x 1 , • • • , x n ) is a function whose latent variables locally correspond to coordinates of the data manifold.Within a local chart, suppose we varied the latent x i while holding all others fixed.This in fact generates a smooth local flow over the manifold, and each coordinate has an associated local flow over the data manifold.Conversely, given a data point p described by factor θ, we have a local flow θ p around p. It turns out that there exists a local chart such that θ p corresponds to a coordinate of that chart.
Theorem 1 (Local Factors of a Disentangling Function).Suppose our data lies on a smooth manifold M , and let f : R n → M be a disentangling function.
For open
U ⊆ R n , if f | U is a local chart of M then each latent x i of f | U corre-
sponds to a unique local factor of variation θ i .
2. Every factor of variation can be locally realized as the latent variable of a disentangling function.
Semantic Meaning
In our definitions of disentanglement and factors of variation, we made no mention of semantic meaningfulness.This was intentional, as semantic meaning is a subjective quality left to the interpretation of the observer.Moreover, there are often multiple ways to meaningfully describe the same data.In language of manifolds, there are multiple meaningful coordinate systems for the data manifold, and the choice of a particular coordinate system is arbitrary.Therefore, we focus on structural properties common to all coordinate systems, and the issue of choosing a particular one is left untouched.
Commutativity and Disentanglement
Theorem 1 of the previous section shows that locally every disentangling function gives rise to a collection of distinct factors.What about the converse: can a set of local factors be realized as the latent variables of a disentangling function?In this section, we establish commutativity between factors as a necessary and sufficient condition for their joint disentanglement.This commutativity criterion serves as a guiding principle for designing disentangling algorithms and suggests that commutativity is a useful "inductive bias"properties that are a priori baked into a learning algorithm to encourage the emergence of good representations (Goyal and Bengio (2022)).In this vein, in Section 4 we demonstrate the utility of enforcing commutativity in the problem of learning matrix exponentials that describe the data.
Local Dynamics of a Factor
Before we get to the main result of this section, we first establish a relevant technical notion.
Recall that locally, a factor of variation is a smooth local flow θ(t, p) on some patch of the data manifold.Working in local coordinates, consider the function X(p) = ∂ ∂t | t=0 θ(t, p) that assigns to each point p the instantaneous change dictated by θ.X(p) captures the local dynamics of factor θ, and X(p) is the manifold analogue of a vector field over R m encountered in vector calculus.This function X(p) is in fact independent of our choice of coordinates, and for every local factor θ we have the associated local vector field X θ .Furthermore, just like how Euclidean vector fields form a real vector space, (local) vector fields over a manifold also have a vector space structure.Hence, we make the following definitions: Definition 3. Given a local factor of variation θ, we call its associated local vector field X(p) ≡ ∂ ∂t | t=0 θ(t, p) the local dynamics of factor θ. Two vector fields are linearly independent if they are pointwise linearly independent.
The Commutativity Criterion
We first define what it means for a collection of factors to commute.Returning to our dataset of portraits, each portrait is an image on a two-dimensional pixel grid.Suppose we generated new images by manipulating the spatial orientation of the portrait subject by two operations: rotating the subject about the center of the pixel grid and translating (shifting) the subject.It is well known that these two operations are not interchangeable: the resulting image depends on the order of their application.On the other hand, changing the lighting condition or shifting the subject results in the same image regardless of the order of their operation.The former is an example of non-commuting factors, while the latter is an example of commuting factors.With this definition of commutativity, we now state the central result of this paper.
θ i (s, θ j (t, p)) = θ j (t, θ i (s, p))
for all pairs i, j and for all s, t, p that lie in the flows' domain.In other words, two factors commute if the end result does not depend on their order of application.
Theorem 2 (The Commutativity Criterion).Let θ 1 , • • • , θ k be a set of local factors whose local dynamics X i are linearly independent.The factors can be locally disentangled -ie.they are the coordinates of a local chart -if and only if they commute.
The condition of linear independence is a technical condition that enforces the factors to be distinct.For example, any factor commutes with itself, and linear independence ensures we do not have copies of the same factor.Theorem 2 shows that commutativity is a central property of disentanglement: the coordinates of a local chart define commuting factors, and a set of factors can be realized as the coordinates of a local chart only if they commute.Note that Theorem 2 does not require that the number of factors equal to the dimension of the data manifold: we can apply the commutativity criterion to any set of factors, even if they only partially describe the data.
Example: Grid-Centric Rotations and Translations
The commutativity criterion implies that it is impossible for a system of non-commuting factors to be jointly disentangled.Consider again the example of grid-centric rotation and translation applied to the portrait dataset.Each operation is a factor of variation, and their disentanglement amounts to a local chart φ: φ(x 1 , x 2 , x 3 ) = p such that x 1 corresponds to grid-centric rotation and x 2 , x 3 correspond to translations.However, as previously mentioned grid-centric rotation does not commute with translation, so no such φ can exist by Theorem 2. It is impossible for any disentangling function to represent these operations.
Now suppose we took a single portrait and generated a new dataset by applying gridcentric rotations and translations to the portrait subject.Is it now possible to learn a function that disentangles the two operations?Again, Theorem 2 asserts that this is impossible.However, we explicitly generated the data through these two operations, so what went wrong?For example, we can certainly define a function that generates the entire dataset by sequentially applying translation and rotation to the original portrait p 0 :
g(x 1 , x 2 , x 3 ) = R(x 1 )T (x 2 , x 3 )p 0
where R(x 1 ) is rotation and T (x 2 , x 3 ) is horizontal and vertical translation respectively.The issue is that the latent variables do not correspond to the original datagenerating operations.Suppose we fixed x 1 = π 4 , so we always apply a fixed rotation after translation.Then, varying x 2 would not translate the portrait subject horizontally but instead translates them along an axis rotated π 4 from the x-axis.Similarly, varying x 3 translates the subject on an axis rotated π 4 from the y-axis.The factors defined by x 2 and x 3 do not correspond to the original data-generating factors of horizontal and vertical translation!Now say we flipped the order of application, so we first apply rotation and then translation:
h(x 1 , x 2 , x 3 ) = T (x 2 , x 3 )R(x 1 )p 0
Suppose the subject of the original portrait p 0 was centered such that their nose was in the center of the pixel grid, and we fix the translation parameters (x 2 , x 3 ) to (3, 3) so the subject is displaced relative to the grid's center.Now if we vary the rotation parameter x 1 , this would result in the subject rotating about their nose displaced (3, 3) units relative to the grid center.In other words, the factor x 1 captures nose-centric rotation rather than grid-centric rotation.Again, we have a factor that does not correspond to the original data-generating factors.
Local Dynamics of Commuting Factors
In fact, we can more precisely analyze the previous example to demonstrate an interesting equivalent characterization of commutativity.Recall that we generated the data by applying grid-centric rotation and translation to the subject of a single portrait p 0 .Let us assume that images have infinite dimension and infinite resolution, so our data can be identified Qiu with the manifold S 1 × R 2 .Around p 0 , we have the local coordinates (x 1 , x 2 , x 3 ) that track orientation and position relative to p 0 respectively, so p 0 has coordinates (0, 0, 0).We again consider the data-generating function g(x 1 , x 2 , x 3 ) = R x 1 T (x 2 , x 3 )p 0 , which in local coordinates has the form:
g : (x 1 , x 2 , x 3 ) → (x 1 , R x 1 [x 2 , x 3 ])
where R x 1 is the 2 × 2 rotation matrix of angle x 1 .Computing the Jacobian of g in this coordinate basis, we see that the associated local coordinate dynamics of g are:
X 1 = ∂ ∂x 1 + (−x 2 sin x 1 − x 3 cos x 1 ) ∂ ∂x 2 + (x 2 cos x 1 − x 3 sin x 1 ) ∂ ∂x 3 X 2 = cos x 1 ∂ ∂x 2 + sin x 1 ∂ ∂x 3 X 3 = − sin x 1 ∂ ∂x 2 + cos x 1 ∂ ∂x 3
Notably, the local dynamics of all three factors involve the angle of rotation x 1 , and their dynamics depend on each other!This explains why grid-centric rotation and translation cannot be disentangled.
The coupling between the local dynamics X i of a pair of factors θ i can be computed through their Lie derivative, denoted L X 1 X 2 .Roughly, L X 1 X 2 computes the change in the local dynamics of factor θ 2 when varying θ 1 .Hence, the local dynamics of the factors are decoupled if they do not depend on other factors, and we formalize this concept.
Definition 5.For local factors {θ i } with local dynamics {X i }, we say their local dynamics are decoupled if:
L X i X j = L X j X i = 0 ∀i = j
That is, the local dynamics of each factor do not depend on the values of other factors.
Theorem 3 (Commutativity and Local Dynamics).A set of local factors commute if and only if their local dynamics are decoupled.
Theorem 3 gives us another way of interpreting why commutativity between factors of variation is so important: it captures the property that a factor of variation affects the data in the same way regardless of the other factors' values.This captures the desiderata that factors of variation encode separate qualities of the data (Bengio et al. (2014)), which by Theorems 2 and 3 is equivalent to commutativity between factors.
Application to Matrix Exponential Operators
In this section, we apply the framework developed so far to algorithms that learn datagenerating operators through the matrix exponential (Cohen and Welling (2014); Miao and Rao (2007); Sohl-Dickstein et al. ( 2017); Xiao and Liu (2020); Chau et al. (2020); Xu and Ma (2012)).While these algorithms might vary in guise and name, their core approach is the same: learning a suitable dictionary of matrices so that their matrix exponential results in a broad of set of data-generating operators.By applying these operators to a data point, one generates new data points that differ from the original in interesting, meaningful ways.We shall see that enforcing commutativity has both theoretical and practical benefits to this class of algorithms.In a later section, we also discuss their relation to the group theoretic definitions of disentanglement.
Problems with the Matrix Exponential
Computing a matrix exponential is relatively expensive (Moler and Van Loan (2003)), and a common computational shortcut (Cohen and Welling (2014); Sohl-Dickstein et al. ( 2017)) is to assume the generators A i are jointly diagonalizable: A i = P D i P −1 for some diagonal matrix D i with common matrix P .For such matrices, the matrix exponential is easy to compute and takes the following form:
exp α i A i = exp α i P D i P −1 = P exp α i D i P −1
where exp( α i D i ) is a diagonal matrix whose entries are the entry-wise exponential of the diagonal matrix α i D i .However, the assumption of joint diagonalization is often not a natural one and is instead invoked as a shortcut.
Another problem when working with sums of matrix generators is that the property e sA+tB = e sA e tB generally holds for all t, s only if A and B are commuting matrices (this directly follows from the Baker-Campbell-Hausdorff formula).This has an important consequence for interpreting the impact of each dictionary element's coefficient.It is well-known that the matrix exponential has the property: ∂ ∂t | t=0 exp{tA} = A.However, this property fails to extend to sums of non-commuting matrices:
∂ ∂α i | α i =0 exp( α i A i ) = A i .
In particular, this means that the data change induced from varying α i does not equal the local flow θ i (α i , p) = exp(α i A i )p.This makes the effect of α i hard to interpret, since its dynamics might be considerably more complicated than the local flow of A i .
Commutativity and the Matrix Exponential
Let us examine the task of learning matrix exponentials from the manifold perspective.Applying the matrix exponential to a point p, we have the local data-generating function:
φ(α 1 , • • • , α n ) = e α i A i p
Again, we associate each dictionary element A i to its canonical factor θ i (t, p) = exp(tA i )p.Under what conditions do the coordinates of φ reflect these dictionary factors?We apply the commutativity criterion of Theorem 2 to establish a simplified form of the matrix exponential.
Qiu
Theorem 4 (Commutativity and the Matrix Exponential).Consider a data-generating operator of the form exp( α i A i ) from a dictionary of linearly independent square matrices A i .At each point p, the coordinates of the data-generating function
f p (α 1 , • • • , α n ) = exp α i A i p
correspond to the dictionary factors θ i (t, p) = exp(tA i )p if and only if the dictionary elements A i commute as matrices.Furthermore, the A i can be simultaneously diagonalized (possibly over C) and the matrix exponential splits into a product of the dictionary factors.
Commutativity of the dictionary elements A i is precisely the condition that allows them to be realized as the factors of a local chart.Furthermore, it justifies the computational shortcut of assuming joint diagonalization and makes it easy to interpret the coefficients of the model.Viewing the data-generating operator as a disentangling function, the manifold disentanglement framework tells us to restrict our attention to dictionaries of commuting matrix generators, which are both easy to work with and interpret.
Distilling and Disentangling Data-Generating Models
In the previous section, we examined disentanglement for a specific type of data-generating model: the matrix exponential.In this section, we show how any smooth data-generating model can be locally distilled and disentangled at points where it is full rank.This implies a possibility result for distilling complex data-generating models into a more compact one, and this compact representation is (almost) the smallest one that still preserves the descriptive power of the original model.
We first define the notion of a data-generating model's local expressivity.Intuitively, a model's local expressivity captures the number of directions one can move the data manifold M by small variations in the model's latent variables.In coordinates, this notion is naturally captured by the rank of model's Jacobian, and at such points a joint distillation and disentanglement procedure is possible.Definition 6.Let f : R m → M be a smooth data-generating function describing the n-dimensional data manifold M .For x ∈ R m , the local rank of f at x is the rank of its differential ∂f x , which in coordinates is the Jacobian of f .We say f is full rank at x if ∂f x is full rank.
Theorem 5 (Distillation and Disentanglement of Models).Let f : R m → M be a smooth data-generating function describing the n-dimensional data manifold M .If f is full rank at x ∈ R m , then there exists a smooth reparametrization ψ of an open set V containing x and a local chart containing f (x) ∈ M with the following property:
1.If the rank of f is m, in coordinates f • ψ −1 takes the form:
f • ψ −1 : (x 1 , • • • , x m ) → (x 1 , • • • , x m , 0, • • • , 0) 2. If the rank of f is n, in coordinates f • ψ −1 takes the form: f • ψ −1 : (x 1 , • • • , x n , • • • , x m ) → (x 1 , • • • , x n )
Corollary 1 (Distillation of Overcomplete Models).Let f : R m → M be a smooth data-generating function describing the n-dimensional data manifold M , with m ≥ n.If f is surjective and full-rank everywhere, then:
1. f can be locally distilled and disentangled using n parameters at every point in its latent space.
2. f can be globally distilled into a function f * defined on an subset of R n+1 that is surjective and full-rank with respect to the first n latent variables.
Theorem 5 shows that there exists a reparameterization ψ of the latent space of a model such that a subset of the reparametrized variables capture all of the possible variation of f .In this sense, the distillation procedure is similar in spirit to dimensionality reduction techniques, and it can be seen as their analogue for data-generating models.Moreover, we see that these reparameterized variables ψ(x) correspond to manifold coordinates, meaning that the data-generating function now also locally disentangles the data.
Corollary 1 captures the common situation of a complex, overcomplete model that fully describes the data.It not only establishes that such overcomplete models can be locally distilled and disentangled, one can also stitch these local distillations into a global one using at most one extra parameter.This alternative model f * is just as expressive as f while having the (almost) minimal number of latent variables, and its latent space is essentially a reparametrized subset of the original latent space of f .Hence, Corollary 1 gives a possibility result that one can always distill an overcomplete model into a more compact one.
Connection to Group Theoretic Disentanglement
In this section, we highlight the connections between our manifold framework and group theoretic approaches to disentanglement.The group theoretic framework equips the data M with a group of symmetries G that act on it, and one seeks to factorize this action into a product of group factors (Higgins et al. (2018); Wang et al. (2021)).Each individual group factor G i controls its own set of data properties, and they are Qiu the group theoretic versions of factors of variation.Under this framework, disentanglement amounts to learning a factorized group action on the data.
G = G 1 × • • • × G n acting on M
In following subsections, we will show that commutativity is an implicit assumption in group factorization.In fact, as is the case in our manifold framework, commutativity is a necessary and sufficient condition for group theoretic disentanglement.Furthermore, many groups of physical significance are Lie groups, and we will show how the group theoretic framework can be recast in the manifold framework when working with Lie groups.
Commutativity and Factorized Group Actions
As previously mentioned, disentanglement in the group theoretic framework amounts to factorizing the group of data symmetries G into a product of subgroups
G = G 1 × • • • × G n ,
where each group factor G i represents an independent set of data properties.For example, in our portrait dataset, the portraits of a subject might be governed by their orientation and position relative to the camera as well as the lighting condition, and the corresponding group of symmetries would be G = SO(3) × R × R 2 .Disentanglement would entail recovery the factorized group structure and its corresponding action on the data.
Interestingly, the product structure of the factorized group implies commutativity between the group factors G i .Each factor G i corresponds to the subgroup (e, • • • , G i , • • • , e) ⊆ G, and these subgroups naturally must commute.For example, multiplication in the product group G = G 1 × G 2 has the following property:
(g 1 , e) * (e, g 2 ) = (g 1 , g 2 ) = (g 2 , e) * (e, g 1 ) ∀g 1 ∈ G 1 , ∀g 2 ∈ G 2
This holds for any product group, even if the factors themselves are not abelian groups.
Conversely, suppose we have a set of factors of variation, which in the group theoretic framework are groups G i acting on the data M .A group action is equivalently a group homomorphism from G i into the automorphism group of M , and our set of factors is equivalent to a set of group homomorphisms f i : G i → Aut(M ).By universality, these homomorphisms must filter through the group coproduct G i :
G i G i Aut(M ) f i f i
However, the group coproduct is the free product, not the product group as required under the group theoretic framework.This is because the factors G i might not commute, and the construction of the induced map f i is order-dependent.Intuitively, this is incompatible with disentanglement, since each G i governs a separate set of data symmetries: the order should not matter when changing different types of symmetries.Again, commutativity seems to capture some instrinsic quality of separateness between factors, and in fact there is a corresponding commutativity criterion for group theoretic disentanglement.
Theorem 6 (Commutativity Criterion for Group Theoretic Disentanglement).Consider a set of group theoretic factors of variation, which are groups G i acting on the data M .They are the factors of a product group action f :
G = G 1 × • • • × G n → Aut(M )
if and only if their actions commute.
Lie Groups and Manifold Disentanglement
Lie groups, groups that are also smooth manifolds, serve as a bridge between the group theoretic framework and our manifold framework.In the case of a Lie group H, a smooth action of H on the data M is a group action that is also smooth.In our manifold framework, factors of variation are in fact also local smooth actions of on the data manifold M , at least restricted to an open interval.Given a smooth action of H on M , at each p ∈ M the data manifold locally inherits a (partial) coordinate chart from H via its orbit map
f p (h) = h • p.
If H is a product group, then M inherits a coordinate chart that is a product of each factor H i 's coordinates.
Theorem 7 (Group-Manifold Disentanglement Correspondence).For a product Lie group H = H 1 × • • • × H k acting smoothly on the data manifold M , at every point p ∈ M there exist coordinate charts containing e ∈ H and p ∈ M respectively such that the orbit map f p has the following coordinate form:
f p : k i=1 (x i1 , • • • , x in i ) → k i=1 (x i1 , • • • , x ij i )
where n i = dim(H i ) and j i ≤ n i .In other words, at every p ∈ M there exists a factorized set of coordinates around p such that the i th factor is induced from a subset of the coordinates of H i .The number of dimensions j i described by each H i is constant within the same orbit.
This results links disentanglement between the group theoretic and manifold frameworks.
The smooth action of any factorized Lie group H induces a correspondingly factorized coordinate chart at each point of M .Each subgroup H i acts on a different set of coordinates of M , and so we have groupings of local coordinates of the data that are controlled by distinct symmetry groups H i .
In fact, a Lie group H that acts transitively on the data manifold, meaning we can transform any data point to another via its action, is a model of M itself.For example, consider the manifold of a subject's portraits.As previously mentioned, the orientation, position, and lighting of the portraits all naturally correspond to the Lie groups SO(3), R 2 , and R respectively.The joint action of these groups allows us to switch between any two of their portraits, and fixing a reference portrait p 0 we can identify each portrait p with a unique group element g p such that p = g p • p 0 .In this sense, the subject's portrait manifold is equivalent to the group of symmetries acting on it.Formally, such spaces are called homogeneous spaces and are essentially quotient manifolds of the symmetry Lie group.
Qiu
Theorem 8. (Homogeneous Spaces and Disentanglement) Suppose Lie group H acts transitively on data manifold M , meaning the orbit map is surjective for every p ∈ M .Then M is diffeomorphic to a quotient manifold of H.If H also acts freely, meaning the orbit map is injective for every p ∈ M , then M is diffeomorphic to H itself.
Revisiting Matrix Exponentials
As a brief aside, we return to the problem of learning matrix exponentials of Section 4. Given a dictionary of matrices A i , the set of matrix exponentials of the form exp( α i A i ) forms a Lie group and in many cases is an embedded Lie subgroup of the general linear group.Each dictionary element A i is a member of the Lie algebra of H, which intuitively gives a linear picture of H around the identity element.The matrix exponential provides a local diffeomorphism between the Lie algebra and its Lie group, and so the dictionary coefficients α i in fact correspond to a local chart of H provided the A i are linearly independent.By Theorem 7, the data manifold M in turn inherits (some of) these coordinates, so the Lie group coordinates α i also serve as manifold coordinates when applying these operators.
Each element of the Lie algebra defines a unique global flow over H, and any commuting, spanning set of dictionary elements A i in fact defines a global chart over H.Such a commuting Lie algebra basis implies that the identity component of H, which is a Lie subgroup, is an abelian group.Thus, working with a commuting dictionary means locally modeling the action of an abelian Lie group, which are all of the form R n × T m where T m is the m-dimensional torus.Such groups are particularly simple to understand: for example, the representation theory of such groups is well-known and easy to compute (Cohen and Welling (2014); Chau et al. (2020)).This reinforces the benefits of commutativity in simplifying the matrix exponential problem.
Connection to Probabilistic Disentanglement
In this section, we highlight the connections between probabilistic definitions of disentanglement and our manifold framework.Broadly, under the probabilistic framework one hopes to learn a factorized latent representation of the data Z = (Z 1 , • • • , Z k ) such that the factors Z i are independent (Higgins et al. (2017); Kim and Mnih (2018); Burgess et al. (2018)).This latent representation might be the latent code of an autoencoder (Kim and Mnih (2018)) , the sources of a signal mixture (Hyvärinen and Oja (2000)), or even the principal axes of the data distribution as in principal component analysis.However, in all cases the factorization into independent Z i is central, and these factors Z i are probabilistic versions of factors of variation.We will detail the effects of commutativity within this probabilistic framework and show how it can be merged with our manifold framework.
Probability Measures in Coordinates
Under the probabilistic framework, the latent representation Z = (Z 1 , • • • , Z k ) gives rise to the data M via a generative function p(M |Z).From the manifold perspective, we can naturally interpret the latent representation Z as local coordinates of M and the generative function p(M |Z) as its (possibly noisy) inverse chart map.Assuming Z is a set of full coordinates describing the manifold patch U ⊆ M , any probability measure on Z induces a unique local measure on U and vice versa.Now, if we have another coordinate system for U , how are the two coordinate measures related?It turns out that these coordinate measures must be consistent with one another and are essentially the same measure under different parameterizations.
Lemma 1 (Consistency of Local Coordinate Measures).For the data manifold M , consider any measure µ on M with respect to its Borel σ-algebra.For any open U ⊆ M , let φ 1 , φ 2 : U → R n be two local charts.Then, 1.For i ∈ {1, 2}, µ| U induces the unique coordinate measure µ i on φ i (U ) via the pushforward map:
µ i = φ * i (µ| U ).
2. Any two coordinate measures are related to each other via their transition map ψ:
µ 2 = ψ * (µ 1 )
3. All three φ 1 , φ 2 , ψ are invertible measurable maps.
On the Impossibility of Probabilistic Disentanglement
We now tackle an impossibility result stating that probabilistic disentanglement is impossible in a general setting (Locatello et al. (2019)).For the rest of this section, we will assume that the data X lies near a manifold M rather than exactly on it, reflected in our notation.The distinction of the data lying on or near the manifold did not matter in previous sections, but we adopt it now for clarity and convenience.
The impossibility result states that given a latent measure P (Z) and likelihood P (X|Z), there exist infinitely many ψ : Z → Z such that ψ(Z) d = Z and the Jacobian ∂ψ has non-zero entries.The alternate latent variables Z = ψ(Z) are entangled with respect to Z since each entry depends on all of Z, yet they induce the same data distribution P (X).Therefore, the two parameterizations Z and Z are indistinguishable when inferring their values from the data, and the recovery of Z is ill-posed.
Viewing this situation from the manifold perspective, the two latent variables Z and Z are different local coordinate systems of the manifold M .By the consistency requirements of Lemma 1, their measures must be pushforwards of each other through their transition map ψ, and they induce the same local measure on the manifold.Now, the crux of the issue lies in the form of the likelihood P (X|Z).Consider the following data generating process:
Z → M → M + ǫ = X
where ǫ is Gaussian noise.In other words, conditioned on a particular point p ∈ M , the data X is normally distributed about p.If φ is the chart map of Z, then the likelihood is P (X|Z) = N (φ −1 (Z), I).A similar situation holds for Z and its chart map φ.Importantly, we see that if a latent point z maps to different points on the manifold under each chart, then we have P (X|Z = z) = P (X| Z = z) since the two Gaussians have different means.Even if Z and Z have the same distribution, they can be still distinguished via their likelihoods!We can extend the conclusion of this particular example to a more general result.
Qiu
Theorem 9 (Likelihoods Distinguish Local Coordinates).Let Z and Z be distinct (partial) local coordinates of the same open U ⊆ M .For data X lying on or near the manifold M , suppose the family of likelihoods {P (X|p)|p ∈ M } is identifiable in M .Then, there exists an open set V such that:
P (X|Z = v) = P (X| Z = v) ∀v ∈ V
When Z and Z have non-negative densities with respect to the Lebesgue measure, Theorem 9 implies that their likelihoods differ on a set of positive probability.Hence, while it might not be possible to distinguish between two local coordinates based on their distributions, one can distinguish between them using their likelihoods.Moreover, note that we can still apply Theorem 9 when we have only a partial description of the manifold, so even an incomplete set of local coordinates can be distinguished.
Indeed, in our manifold framework, the impossibility result essentially states that given a local coordinate system, there are infinitely many other coordinate systems whose transition maps preserve its coordinate measure.The consistency condition of Lemma 1 ensures that any two coordinate measures induce the same measure on M and hence on the data X.Therefore, it is impossible to infer the values of a particular set of coordinates from the data, since there are are infinitely many coordinate charts with the same measure that describe a manifold patch.Instead, one must choose a particular coordinate system independently of the data by fixing the likelihood and hence local chart map, making the problem of recovering its coordinates become well-posed.In light of this, the task of finding a factorized latent representation Z requires the recovery of a local chart map, and the goal of probabilistic disentanglement aligns with the goal of manifold disentanglement.
Commutativity and Probabilistic Disentanglement
Here, we establish an analogous commutativity criterion for probabilistic disentanglement in a Bayesian setting.Recall that factors of variation in our manifold framework are local flows over the data manifold, and we will use the shorthand
θ t i p ≡ θ i (t i , p). Given a set of local factors θ 1 , • • • , θ k at p ∈ M , we have a local data-generating function f : T → M defined on T ⊆ R k : f (t 1 , • • • , t k ) = θ t 1 • • • • • θ t k p
Any probability measure over the factor values T = (T 1 , • • • , T k ) naturally induces a corresponding local measure on M and hence on X.However, if the factors θ i do not commute, then the data-generating function depends on their order of application and knowing just the factor values T does not specify a location on the manifold.Treating the order of application σ as a random variable, our likelihood then becomes a mixture:
P (X|T = T 1 , • • • , T k ) = σ∈S k P (σ)P (X|T ; σ)
where P (X|T ; σ) = P (X|f (t σ(1) , • • • , t σ(k) ).Non-commutativity introduces ambiguity in the manifold location, expressed as a mixture of different likelihoods.For example, again suppose the data X is conditionally Gaussian about the manifold M .Then, non-commutativity of the factors causes P (X|T ) to be a mixture of Gaussians, and the mixture becomes only becomes a single Gaussian when the factors commute.We generalize this example to the following result.
Theorem 10 (Commutativity and Probabilistic Disentanglement).Let θ 1 , • • • , θ k be a set of local factors at p ∈ M , and let T = (T 1 , • • • , T k ) be their joint time domain at p. Suppose the family of likelihoods {P (X|m)|m ∈ M } is identifiable in M and affinely independent.The likelihood of X given T takes the form:
P (X|T ) = σ∈S k P (σ)P (X|T ; σ) = σ∈S k P (σ)P (X|f σ (T ))
The likelihood P (X|T ) is not a mixture if and only if the factors commute.
In a probabilistic setting, commutativity between the factors means that the manifold location is fully specified from the flow parameters T alone, as the order of application does not matter.This in turn implies that our likelihood P (X|T ) is not a mixture, which might be advantageous for computational reasons.Especially in Bayesian settings where computational concerns are prominent, being able to guarantee that the posterior is not a mixture is a desirable property to have.
Sources of Noise in the Likelihood
In many parts of this section, we assumed that the data X did not lie exactly on the manifold M , and we often invoked a noisy data-generating process so that the likelihood P (X|Z) did not collapse into a single point.While our results can be applied even if the likelihood collapses to a single point, the non-point likelihoods were more illustrative.Furthermore, assuming a noisy setting is not the only way to prevent the likelihood from collapsing.For example, Z might be an partial set of coordinates so we are not able to specify the manifold location given Z.In that case, we may consider a noiseless setting and still have a non-point likelihood.
Conclusion
In this paper, we define disentanglement and factors of variation from the perspective of manifolds, unifying disentanglement with the manifold hypothesis.Under our framework, disentanglement amounts to recovering the data manifold's local coordinates.Along the way, we established that commutativity between factors is of central importance to disentanglement, capturing the property of separateness between factors.We studied the application of our framework to the problem of learning matrix exponentials, showing how enforcing commutativity makes the solution computationally tractable and easy to interpret.We then tackled the problem of distilling data-generating models, establishing the existence of a local procedure that simultaneously distills and disentangles a data-generating model.Finally, we related our manifold framework to other disentanglement frameworks: group theoretic and probabilistic.In each case, we demonstrated how each framework can be integrated within the manifold framework.Importantly, we also established an analogous commutativity criterion for each alternative framework, demonstrating that commutativity is central to disentanglement regardless of what framework one works in.We hope that this paper highlights the utility of the manifold framework of disentanglement and stimulates further research into the role of commutativity in disentanglement.
Acknowledgements
The author would like to thank Giles Hooker for his many helpful comments and suggestions in presenting the ideas of this paper.The author is also indebted to Bruno Olshausen, Yubei Chen, and Ho Yin Chau for the many stimulating discussion about disentanglement, and our previous joint work sparked the ideas contained here.
N. Zheng andJ. Xue. Manifold Learning, pages 87-119. Springer London, London, 2009. ISBN 978-1-84882-312-9. doi: 10.1007 Theorem 6
Proof Given the product group structure G = G 1 × • • • × G n , the subgroup associated with each factor must commute.As f is a group homomorphism, their images f (G i ) must also commute in Aut(M ).Conversely, suppose we have a collection of group homomorphisms
f i : G i → Aut(M ). Then, one can define a map f : G → Aut(M ) via f (g 1 , • • • , g n ) = f 1 (g 1 ) * • • • * f n (g n ). Since f i (G i ) ⊆ Aut(M ) commute, f is in fact a group homomorphism: f (g 1 * g ′ 1 , • • • , g n g ′ n ) = f 1 (g 1 * g ′ ) * • • • * f n (g n * g ′ n ) = f 1 (g 1 ) * f 1 (g ′ 1 ) * • • • * f n (g n ) * f n (g ′ n ) = [f 1 (g 1 ) * • • • * f n (g n )] * [f 1 (g ′ 1 ) * • • • * f n (g ′ n )] = f ((g 1 , • • • , g n ) * (g ′ 1 , • • • , g ′ n ))
The second equality follows from the fact that each f i is a group homomorphism, and the third equality follows from commutativity of the subgroups f i (G i ) ⊆ Aut(M ).The other properties of a group homomorphism are similarly checked using a similar computation.
Theorem 7
Proof For any p ∈ M , the orbit map f p : H → M is an equivariant map, viewing H as a H-set under self-multiplication.Hence, the orbit map is constant rank by Theorem 7.25 of Lee (2003).Since H is a product manifold with a product group action, we can apply the Rank Theorem to each factor group's coordinates.For p ∈ M , every p ′ ∈ Orb(p) can be expressed as p ′ = h ′ • p for some h ′ ∈ H. Therefore,
f p ′ = f p • R h ′ where R h ′ is right multiplication by h ′ . As R h ′ is a diffeomorphism, f p ′ has the same rank as f p .
Theorem 8
Proof This is just a restatement of the Homogenous Space Characterization Theorem (Theorem 21.19 of Lee (2003)).The latter claim follows since M is diffeomorphic to H/Stab(p) under the above theorem and that Stab(p) = e if H acts freely.
Lemma 1
Proof For the first claim, since U is open and M is equipped with the Borel σ-algebra, µ restricts to local measure µ| U .Equipping φ i (U ) ⊆ R n with its Borel σ-algebra inherited from R n , as φ i is homeomorphism it is an invertible measurable map and the pushforward µ i = φ * i (µ| U ) is unique.Since U and φ i (U ) are related by an invertible measurable map, the only valid coordinate measure on φ i (U ) is φ * i (µ| U ) in order to be consistent with µ| U .As usual, equality and uniqueness is up to sets of measure 0. To prove the second claim, we note that since φ 1 is an invertible measurable map we have µ| U = φ −1 * 1 (µ 1 ).We then
Qiu calculate: µ 2 = φ * 2 (µ| U ) = φ 2 (φ −1 * 1 (µ 1 )) = (φ 2 • φ −1 1 ) * (µ 1 ) As ψ = φ 2 • φ −1
1 , we have the second claim.To finish the third claim, we note that the transition map ψ is also a homeomorphism and hence a invertible measurable map with respect to the Borel σ-algebras.
Theorem 9
Proof Let Z and Z be distinct local coordinates of an open set U ⊆ M with chart maps φ and φ respectively.If they are distinct coordinate systems, there exists at least one point x such that φ −1 (x) = φ−1 (x).Since M is Hausdorff, there exist disjoint open sets W and W containing φ −1 (x) and φ−1 (x) respectively.Then,
V = φ(W ∩ U ) ∩ φ( W ∩ U ) is an open set containing x such that φ −1 (v) = φ−1 (v) for all v ∈ V . As P (X|Z = v) = P (X|φ −1 (v)) and P (X| Z = v) = P (X| φ−1 (v))
, since the likelihoods are identifiable in M we have the result.A similar proof establishes the result for a set of partial coordinates, as long as the family of likelihood are identifiable in M .
Theorem 10
Proof In general, given the factor values T the likelihood takes the form:
P (X|T ) = σ∈S k P (σ)P (X|f σ (T ))
where f σ (T ) correspond to the action of the factors in order σ and P (σ) is our prior over the order.Since the family is identifiable and affinely independent, we see that the likelihood is not a mixture if and only if P (X|f σ (T )) is the same for all σ ∈ S n .This is equivalent to f σ being the same for all σ, which is equivalent to the factors commuting.
B. Smooth Manifolds: Technical Overview
We give a brief technical overview of smooth manifolds.For thorough references, we point the reader in the direction of Lee's introductory texts on smooth manifolds (Lee (2003)) and Riemmanian manifolds (Lee (2019)) as well as Hall's text on Lie groups (Hall (2010)).
B.1 Smooth Manifolds
A manifold is a space that locally looks like Euclidean space, much like how a sphere locally looks like a plane.More formally, a n-dimensional manifold M is a second-countable Hausdorff space equipped with a collection of local charts φ i : V i → U i .Here, the V i form an open cover of M , and each local chart is a homeomorphism between an open set in the manifold V i ⊆ M and an open set in Euclidean space U i ⊆ R n .Unpacking this definition, a manifold is some space with a collection of small patches that tile it, and each patch is associated with its own chart map that gives a bijective mapping between the manifold patch and a corresponding patch of Euclidean n-space.If we consider each dimension of Euclidean space as a spatial coordinate, the chart map φ i gives the n local coordinates of the patch V i .Hence, manifolds are locally equivalent to patches of Euclidean space.
A manifold is smooth if the transition maps between its local coordinates are smooth maps with smooth inverse.That is, consider the neighborhood V 1 ∩ V 2 , which is the intersection between the local charts φ 1 : V 1 → U 1 and φ 2 : V 2 → U 2 .These give two coordinate systems describing V 1 ∩ V 2 , and we require that reparameterizing from coordinates U 1 to coordinates U 2 be a smooth function φ 1 • φ −1 2 : U 1 → U 2 with smooth inverse.Note that the transition map is just a map between open subsets of Euclidean space, and so we can interpret smoothness in the usual Euclidean sense.In summary, a smooth manifold is a manifold where reparameterization of local coordinates is smooth.
Finally, we define smooth maps between smooth manifolds.We say a map f :
M → N is smooth if at each p ∈ M there exist open patches U ⊆ M and V ⊆ N such that: p ∈ U , f (p) ∈ f (U ) ⊂ V ,
and the maps between their coordinates is smooth.That is, restricting the map f to local coordinate patches, the map f is a smooth map if it is smooth in local coordinates.
B.2 Tangent Spaces, the Tangent Bundle, and Vector Fields Each point p on the smooth manifold M has an associated vector space called the tangent space, denoted T p M .Intuitively, the tangent space T p M is the set of directional derivatives along the manifold at p, and we can interpret an element of the tangent space v ∈ T p M as the derivative along velocity v.For example, consider the unit sphere.The tangent space at a point p on the sphere is isomorphic as a vector space to R 2 , and visually it's represented by the tangent plane to the sphere at p. Every vector in this plane represents a possible direction we could move on that sphere.Note that the vector perpendicular to this plane does not lie in the tangent space -it represents a direction that takes us off the sphere.
Consider a smooth function between smooth manifolds f : M → N .At every p ∈ M , f induces a linear map between the tangent spaces T p M and T f (p) N , and we call this induced map the differential ∂f p .Representing f in local coordinates, the differential ∂f p coincides with the Jacobian of f at p. Just as the Jacobian linearly maps directional derivatives in one space to another, the differential is a linear map between tangent spaces.As a linear map, we define the rank of the differential ∂f p to be its rank as a linear map.For a smooth map f : M → N with dim(M ) = m and dim(N ) = n, we say that f is a map of constant rank of its differential has the same rank at every p ∈ M .If f has constant rank m we say that it is a smooth immersion, and if f has constant rank n we say that it is a smooth submersion.Intuitively, smooth immersions are those that locally are smooth embeddings, where the coordinates of M are a subset of those of N .Similarly, smooth submersions admit local sections, where the coordinates of N are a subset of those of M .Now we define vector fields over a manifold M .In the Euclidean case, a vector field assigns a directional derivative to each point, and analogously a vector field on a manifold M assigns to each point p ∈ M an element of its tangent space T p M .If we take the disjoint union of the tangent spaces of each point in the manifold T p M , the resulting set has a natural atlas of charts induced from M .This makes it into another manifold called the Qiu tangent bundle T M .Returning to vector fields, we define smooth vector fields as smooth functions X : M → T M such that X(p) ∈ T p M ⊆ T M .
B.3 Smooth Flows and Lie Derivatives
We define a smooth flow on a manifold M as a smooth function θ : D × M → M , where D × p ⊆ R is some open interval containing 0 for every p such that: θ(t, θ(s, p)) = θ(t + s.p) ; θ(0, p) = p
We may also restrict the flow to be defined locally over some open set U ⊂ M rather than the entire manifold.
Importantly the coordinates of a local chart (U, φ) have their associated flows.First, in coordinate space φ(U ) consider the flow along the i th dimension: θi (t, x) = x + te i where e i is the i th coordinate vector.This flow has its corresponding vector field Xi that at each point x assigns ∂ ∂x i | x ∈ T x R n .The flow and its associated vector field are related through the following relation
Xi (x) = ∂ ∂t | t=0 θi (t, x)
and so we say that Xi is the infinitesimal generator of θi .In turn, through the inverse local chart map φ −1 , θi induce a flow θ i on the manifold patch U .Similarly, the differential ∂φ −1 maps Xi to a corresponding vector field X i on U , and X i is the infinitesimal generator of θ i .We call θ i the coordinate flows of the local chart, and every coordinate chart has its own unique set of coordinate flows.Intuitively, we can think of the infinitesimal generator X of a smooth flow θ as defining dynamics over the manifold.If we started at p ∈ M and followed the dynamics of X for time t, we would end up at the point θ(t, p).In this way, the flow of a vector field returns the ending location on the manifold after starting at p and following the vector field for time t.
Having defined the notion of a vector field and its associated smooth flow, we can now tackle the Lie derivative.The Lie derivative L X 1 X 2 of vector field X 2 with respect to vector field X 1 is another vector field whose value at every point is the change in X 2 along the flow of X 1 .Point-wise it has the complicated form:
L X 1 X 2 | p = ∂ ∂t | t=0 ∂θ −t | θ(t,p) X θ(t,p)
where θ −t (p) = θ(−t, p).Since the Lie derivative is antisymmetric, if L X 1 X 2 = 0 then L X 2 X 1 = 0 also and vice versa: invariance under the other's flow is a symmetric property.It turns out that the Lie derivative coincides with the Lie bracket operation, a bilinear operation taking two vector fields and returning another vector field.The Lie bracket often gives an easier way to compute the Lie derivative between two vector fields: for example, in Euclidean coordinates the Lie bracket of the general linear group GL(n, R) is the matrix commutator bracket.
Definition 4 .
4
Given a set of local factors {θ i }, they commute if:
/978-1-84882-312-9 4. S. Zhou, E. Zelikman, F. Lu, A. Y. Ng, G. Carlsson, and S. Ermon.Evaluating the disentanglement of deep generative models through manifold topology, 2021.
QiuA. ProofsTheorem 1Proof The first claim is a basic property of a local chart (φ, U ), where the coordinate flows in φ(U ) are mapped to smooth flows on U via the diffeomorphism φ.For the second claim, if the vector field of a local flow θ is 0 at p, then θ is constant at p on some interval containing 0 (Proposition 9.21 ofLee (2003)).Since our factors are non-degenerate, their vector fields must be non-zero at every point.The second claim then follows from Theorem 9.2.2 ofLee (2003).Theorems 2 and 3Proof A set of smooth local flows commute if and only if their vectors fields commute by Theorem 9.44 ofLee (2003), establishing Theorem 3. Since we assumed the vector fields are linearly independent, Theorem 2 is a statement of the canonical form of commuting vector fields (Theorem 9.46 ofLee (2003)).Theorem 4Proof The dictionary factors are global flows, since they are the action of the one-parameter subgroups γ i (t) = exp(tA i ) at each point p.Hence, the flows commute if and only if the one-parameter subgroups commute.By the Baker-Campbell-Hausdorff formula (Theorem 5.3 ofHall (2010)), this is true if and only if the generators A i commute.It is well-known that commuting matrices can be simultaneously diagonalized, and every matrix can be diagonalized over C.Theorem 5 and Corollary 1Proof If the differential of a smooth function f : R m → M is full-rank at x ∈ R m , there exists an open U ⊆ R m containing x such that f | U is a smooth immersion or submersion (Proposition 4.1 of Lee (2003)).Hence, on this U we may apply the Rank Theorem (Theorem 4.12 of Lee (2003)) to get Theorem 5.The first claim of the corollary is a consequence of Theorem 5.For the second claim, for every p ∈ M there is an x p ∈ R m such that f (x p ) = p since f is surjective.Let V p and U p be the coordinate charts of Theorem 5 containg x p and p respectively.The set {U p } p∈M forms an open cover of M , so there exists a countable open subcover {U α } α∈Z .Let W α be the projection onto the first n-coordinates of the reparametrization ψ(V α ).We can then define the distilled version f * on the set α (W α × {α}) ⊆ R n+1 as:Hence, using one more parameter to distinguish the local chart, f * is surjective and fullrank at every point in its latent space.
Y Bengio, Deep learning of representations: Looking forward. 2013
Representation learning: A review and new perspectives. Y Bengio, A Courville, P Vincent, 2014
Why deep learning works: A manifold disentanglement perspective. P P Brahma, D Wu, Y She, 10.1109/TNNLS.2015.2496947IEEE Transactions on Neural Networks and Learning Systems. 27101997-2008, 2016
Understanding disentangling in β-vae. C P Burgess, I Higgins, A Pal, L Matthey, N Watters, G Desjardins, A Lerchner, 2018
Disentangling images with lie group transformations and sparse coding. H Y Chau, F Qiu, Y Chen, B Olshausen, Arxiv. 2020
The sparse manifold transform. Y Chen, D Paiton, B Olshausen, Advances in Neural Information Processing Systems. S Bengio, H Wallach, H Larochelle, K Grauman, N Cesa-Bianchi, R Garnett, Curran Associates, Inc201831
Learning the irreducible representations of commutative lie groups. T Cohen, M Welling, II-1755-II-1763. JMLR.orgProceedings of the 31st International Conference on International Conference on Machine Learning. the 31st International Conference on International Conference on Machine Learning201432
Testing the manifold hypothesis. C Fefferman, S Mitter, H Narayanan, 10.1090/jams/852Journal of the American Mathematical Society. 292016
Inductive biases for deep learning of higher-level cognition. A Goyal, Y Bengio, 10.1098/rspa.2021.0068Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 478202100682266. 2022
Lie Groups, Lie Algebras, and Representations: An Elementary Introduction. B C Hall, Graduate Texts in Mathematics. 2222010SpringerISBN 9781441923134
beta-vae: Learning basic visual concepts with a constrained variational framework. I Higgins, L Matthey, A Pal, C P Burgess, X Glorot, M M Botvinick, S Mohamed, A Lerchner, 5th International Conference on Learning Representations. Conference Track Proceedings. Toulon, France2017. April 24-26, 2017. 2017
Towards a definition of disentangled representations. I Higgins, D Amos, D Pfau, S Racaniere, L Matthey, D Rezende, A Lerchner, 2018Arxiv
Independent component analysis: algorithms and applications. A Hyvärinen, E Oja, 10.1016/S0893-6080Neural Networks. 0893-60801342000
Disentangling by factorising. H Kim, A Mnih, Proceedings of the 35th International Conference on Machine Learning. J Dy, A Krause, the 35th International Conference on Machine LearningPMLRJul 201880
Introduction to Riemannian Manifolds. Graduate Texts in Mathematics. J Lee, 2019Springer International PublishingISBN 9783319917542
J M Lee, 10.1007/978-0-387-21752-91Smooth Manifolds. New York, New York, NYSpringer2003
Challenging common assumptions in the unsupervised learning of disentangled representations. F Locatello, S Bauer, M Lucic, G Raetsch, S Gelly, B Schölkopf, O Bachem, PMLR, 09-15Proceedings of the 36th International Conference on Machine Learning. K Chaudhuri, R Salakhutdinov, the 36th International Conference on Machine LearningJun 201997
Learning the lie groups of visual invariance. X Miao, R P N Rao, Neural Comput. 1910Oct. 2007
Nineteen dubious ways to compute the exponential of a matrix, twenty-five years later. C Moler, C Van Loan, 10.1137/S00361445024180SIAM Review. 4512003
Learning to disentangle factors of variation with manifold interaction. S Reed, K Sohn, Y Zhang, H Lee, Proceedings of the 31st International Conference on Machine Learning. E P Xing, T Jebara, the 31st International Conference on Machine LearningBejing, ChinaPMLRJun 201432
Nonlinear dimensionality reduction by locally linear embedding. S T Roweis, L K Saul, 10.1126/science.290.5500.2323Science. 29055002000
An unsupervised algorithm for learning lie group transformations. J Sohl-Dickstein, C M Wang, B A Olshausen, 2017
A global geometric framework for nonlinear dimensionality reduction. J B Tenenbaum, V Silva, J C Langford, 10.1126/science.290.5500.2319Science. 29055002000
Self-supervised learning disentangled group representation as feature. T Wang, Z Yue, J Huang, Q Sun, H Zhang, Advances in Neural Information Processing Systems. M Ranzato, A Beygelzimer, Y Dauphin, P Liang, J W Vaughan, Curran Associates, Inc202134
Generative flows with matrix exponential. C Xiao, L Liu, Proceedings of the 37th International Conference on Machine Learning. H D Iii, A Singh, the 37th International Conference on Machine LearningPMLRJul 2020119
Applications of lie groups and lie algebra to computer vision: A brief survey. Q Xu, D Ma, 10.1109/ICSAI.2012.62234492012 International Conference on Systems and Informatics (ICSAI2012). 2012
| [
-0.09008430689573288,
-0.02474946342408657,
0.035545714199543,
-0.04205423593521118,
0.030069272965192795,
-0.018539808690547943,
0.09463523328304291,
-0.11820439249277115,
0.11145192384719849,
0.031610772013664246,
0.09552270919084549,
-0.05599604547023773,
0.09010989964008331,
0.10239783... |
Speaker Identification in Shouted Talking Environments Based on Novel Third-Order Hidden Markov Models
Ismail Shahin ismail@sharjah.ac.ae
Department of Electrical and Computer Engineering
University of Sharjah Sharjah
United Arab Emirates
Speaker Identification in Shouted Talking Environments Based on Novel Third-Order Hidden Markov Models
8CD6CD911C006C3C425C1A64F810C0F2First-order hidden Markov modelssecond-order hidden Markov modelsshouted talking environmentsspeaker identificationthird-order hidden Markov models
In this work we propose, implement, and evaluate novel models called Third-Order Hidden Markov Models (HMM3s) to enhance low performance of text-independent speaker identification in shouted talking environments.The proposed models have been tested on our collected speech database using Mel-Frequency Cepstral Coefficients (MFCCs).Our results demonstrate that HMM3s significantly improve speaker identification performance in such talking environments by 11.3% and 166.7% compared to second-order hidden Markov models (HMM2s) and first-order hidden Markov models (HMM1s), respectively.The achieved results based on the proposed models are close to those obtained in subjective assessment by human listeners.
I. INTRODUCTION
Speaker recognition has two types: speaker identification and speaker verification (authentication).Speaker identification is the process of automatically deciding who is speaking from a set of known speakers.Speaker verification is the process of automatically accepting or rejecting the identity of the claimed speaker.Speaker identification can be used in criminal investigations to determine the suspected persons who uttered the voice captured at the scene of the crime.Speaker identification can also be used in civil cases or for the media.Speaker verification is widely used in security access to services via a telephone, including home shopping, home banking transactions using a telephone network, security control for private information areas, remote access to computers, and many telecommunication services [1].Based on the text to be spoken, speaker recognition is categorized into text-dependent and textindependent cases.In the text-dependent case, speaker recognition requires the speaker to generate speech for the same text in both training and testing; on the other hand, in the text-independent case, speaker recognition does not depend on the text being spoken.
II. LITERATURE REVIEW
Many studies in speech recognition area and speaker recognition area focus on speech uttered in neutral talking environments [1], [2], [3], [4] and on speech produced in stressful talking environments [5], [6], [7], [8].In literature, many studies that focus on the two areas in stressful talking environments study the two areas in shouted talking environments [8], [9], [10], [11], [12], [13], [14].Some talking environments are designed to simulate speech generated by different speakers under real stressful talking conditions.Hansen, Cummings, and Clements employed Speech Under Simulated and Actual Stress (SUSAS) database in which eight talking conditions are used to simulate speech uttered under real stressful talking conditions and three real talking conditions [5][6][7].The eight talking conditions are neutral, loud, soft, angry, fast, slow, clear, and question.The three talking conditions are 50% task, 70% task, and Lombard.Chen used six talking environments to simulate speech under real stressful talking environments [8].These environments are neutral, fast, loud, Lombard, soft, and shouted.Shouted talking environments are defined as when speakers shout, their intention is to produce a very loud acoustic signal, either to increase its range of transmission or its ratio to background noise.
Chen [8] studied talker-stress-induced intraword variability and an algorithm that pays off for the systematic changes observed based on hidden Markov models (HMMs) trained by speech tokens under different talking conditions.Raja and Dandapat [9] studied speaker recognition under stressed conditions to improve the decreased performance under such conditions.They used four distinct stressed conditions of SUSAS database.These conditions are neutral, angry, Lombard, and question.They concluded that the least speaker identification performance happened when speakers talk in angry talking environments [9].Angry talking environments are used as alternatives to shouted talking environments since they can not be totally separated from shouted talking environments in our genuine life [11], [12], [13], [14].Zhang and Hansen [10] reported on the analysis of characteristics of the speech in five different vocal modes: whispered, soft, neutral, loud, and shouted; and to recognize discriminating features of speech modes.Shahin focused in four of his earlier studies [11], [12], [13], [14] on improving speaker identification performance in shouted talking environments using each of Second-Order Hidden Markov Models (HMM2s) [11], Second-Order Circular Hidden Markov Models (CHMM2s) [12], Suprasegmental Hidden Markov Models (SPHMMs) [13], and Second-Order Circular Suprasegmental Hidden Markov Models (CSPHMM2s) [14].The attained speaker identification performance in such talking environments is 59.0%, 72.0%, 75.0%, and 83.4% based on HMM2s, CHMM2s, SPHMMs, and CSPHMM2s, respectively [11], [12], [13], [14].
Most of the works carried out in speech recognition field and speaker recognition field based on HMMs have been conducted using First-Order Hidden Markov Models (HMM1s) [8], [15], [16].HMM1s give extremely high speaker recognition performance in neutral talking environments [8], [11], [14], while they yield very low performance in shouted talking environments [8], [11], [14].Mari et al. [17], [18] proposed, applied, and tested HMM2s in the training and testing phases of a connected word recognition system under neutral talking condition.They attained very high performance using such models.Shahin [11] exploited these models in the training and testing phases of isolated-word text-dependent speaker identification systems under each of neutral and shouted talking conditions.Based on his work and using HMM2s, Shahin [11] achieved higher speaker identification performance than that using HMM1s under shouted talking condition.
The aim of this work is to propose, implement, and evaluate novel models called Third-Order Hidden Markov Models (HMM3s) to further enhance (compared to HMM2s) text-independent speaker identification performance in shouted talking environments.Speaker recognition in shouted talking environments can be used in criminal investigations to recognize the suspected persons who uttered voice in shouted talking envieonments and in the applications of talking condition recognition.Talking condition recognition can be used in medical applications, telecommunications, law enforcement, and military applications [19].The proposed models have been evaluated on our collected speech database and SUSAS database.
The rest of the paper is structered as follows: Brief overview of hidden Markov models is given in Section III.The details of the proposed third-order hidden Markov models are covered in Section IV.Section V describes the collected speech database used in this work and the extraction of features.Speaker identification algorithm based on HMM3s and the experiments are discussed in Section VI.Section VII demonstrates the results achieved in the current work and their discussion.Finally, concluding remarks are presented in Section VIII.
III. BRIEF OVERVIEW OF HIDDEN MARKOV MODELS
HMMs can be described as being in one of the N different states: 1, 2, 3,…, N, at any discrete time instant t.The individual states are denoted as,
N 3 2 1 s ,..., s , s , s s
which are generators of a state sequence q t , where at any time t: q = {q 1 ,q 2 ,…, q T }, T is the length or duration of an observation sequence O of a speech signal.At any discrete time t, the model is in a state q t .At the discrete time t, the model makes a random transition to a state q t+1 .The state transition probability matrix A determines the probability of the next transition between states,
A = [ a ij ] i, j = 1, 2,…, N
where a ij denotes the transition probability from a state i to a state j.
IV. THIRD ORDER HIDDEN MARKOV MODELS
In HMM1s, the underlying state sequence is a firstorder Markov chain where the stochastic process is expressed by a 2-D matrix of a priori transition probabilities (a ij ) between states s i and s j where a ij is given as [15], [16],
i s 1 t q j s t q Prob ij a (1)
In HMM2s, the underlying state sequence is a secondorder Markov chain where the stochastic process is defined by a 3-D matrix (a ijk ).Therefore, the transition probabilities in HMM2s are given as [17],
i s 2 t q , j s 1 t q k s t q Prob a ij k (2)
with the constraints,
1 j i, N 1 a N 1 k ij k
In HMM3s, the underlying state sequence is a thirdorder Markov chain where the stochastic process is specified by a 4-D matrix (a ijkw ).Consequently, the transition probabilities in HMM3s are given as,
i s 3 t q , j s 2 t q , k s 1 t q w s t q Prob a ijkw (3) with the constraints, 1 k j, i, N 1 a N 1 w ij kw The probability of the state sequence, , q ,..., 2 q , 1 q Δ Q T is defined as: T 4 t t q 1 t q 2 t q 3 t q 3 q 2 q 1 q 1 q a a (Q) Prob (4)
where i Ψ is the probability of a state s i at time t = 1, a ijk is the probability of transition from a state s i to a state s k at time t = 3. a ijk can be computed from (2)
T 4 t t t q t q 1 t q 2 t q 3 t q 3 3 q 3 q 2 q 1 q 1 q 1 q ) (O b a . ) (O b a ) 1 (O b λ) O (Q, Prob (5)
Extended Viterbi and Baum-Welch Algorithms:
Based on the probability of the partial alignment ending at a transition (s k ,s w ) at times (t-1, t), the most likely state sequence can be found as:
1 w k, , j N 3, t T λ t O ,..., 2 O , 1 O , w s t q , k s 1 - t q , j s 2 t q ,..., 1 q Prob Δ w) k, j, ( t δ (6)
Recursive computation is given by:
1 w k, j, N 4, t T ) t (O w b . a . k) j, (i, 1 t δ max w) k, (j, t δ ij kw 1 i N (7)
The forward function t (j,k,w) defines the probability of the partial observation sequence, O
1 w k, , j N 3, t T λ w s t q , k s 1 t q , j s 2 t q , t O ,..., 1 O Prob Δ w) k, (j, t α (8) t (j,k,w
) can be computed from the two transitions: (s i ,s j ,s k ) and (s j ,s k ,s w ) between states s i and s w as:
1 w k, j, N 3, t 1 T ) (O b . a . k) j, (i, α w) k, (j, α N 1 i 1 t w ij kw t 1 t (9)
The backward function t (i, j, k) can be defined as:
1 k j, i, N 3, t 1 T λ , s q , s q , i s q T O ,..., O Prob Δ k) j, (i, β k t j 1 t 2 - t 1 t t (10)
The last equation defines t (i,j,k) as the probability of the partial observation sequence from t+1 to T given the model and the transition (s i ,s j ,s k ) among times: t-2, t-1, and t.
V. SPEECH DATABASE AND EXTRACTION OF FEATURES A. Collected Speech Database
In the current work, the proposed models have been assessed on our collected speech database.Eight sentences were captured in each of neutral and shouted talking environments in this database.The eight sentences are:
1) He works five days a week.
2) The sun is shining.
3) The weather is fair.4) The students study hard.5) Assistant professors are looking for promotion.6) University of Sharjah.7) Electrical and Computer Engineering Department.8) He has two sons and two daughters.
Forty (twenty male students and twenty female students) healthy adult native speakers of American English were asked to utter these sentences.The forty speakers were untrained to avoid exaggerated expressions.Each speaker was separately asked to utter each sentence several times in each of neutral and shouted talking environments.The total number of utterances recorded in both talking environments was 4320 ((40 speakers × first 4 sentences × 9 repetitions/sentence in neutral talking environment) + (40 speakers × last 4 sentences × 9 repetitions/sentence × 2 talking environments)).The collected database was captured in a clean environment by a speech acquisition board using a 16-bit linear coding A/D converter and sampled at a sampling rate of 16 kHz.The database was a wideband 16-bit per sample linear data.
B. Extraction of Features
In this work, the features that have been adopted to model the phonetic content of speech signals are called Mel-Frequency Cepstral Coefficients (static MFCCs) and delta Mel-Frequency Cepstral Coefficients (delta MFCCs).These coefficients have been used in stressful speech and speaker recognition areas since such coefficients outperform other features in the two areas and because they provide a high-level approximation of human auditory perception [20], [21].
In this work, a 32-dimension feature analysis of both static MFCC and delta MFCC (16 static MFCCs and 16 delta MFCCs) was used to form the observation vectors in each of HMM1s, HMM2s, and HMM3s.The number of states that was used in the experiments was 6 in each model.The number of mixture components, M, was 5 per state, with a continuous mixture observation density was selected for each model.
VI. SPEAKER IDENTIFICATION ALGORITHM BASED ON EACH OF HMM1S, HMM2S, AND HMM3S AND THE EXPERIMENTS
In the training phase of each of HMM1s, HMM2s, and HMM3s (completely three separate phases) the v th speaker model has been derived using the first four sentences of the speech database with 9 repetitions per sentence uttered in the neutral talking environment.The total number of utterances that has been used to derive the v th speaker model in each training phase is 36 (4 sentences × 9 repetitions/sentence).Training of models in HMM1s, HMM2s, and HMM3s training phases uses first-order, second-order, and third-order forward-backward algorithm, respectively.
In the identification phase of each of HMM1s, HMM2s, and HMM3s (completely three separate phases), each one of the forty speakers used separately the last four sentences of the database (text-independent) with 9 repetitions per sentence in each of neutral and shouted talking environments.The total number of utterances that has been used in each phase per talking environment was 1440 (40 speakers × 4 sentences × 9 repetitions/sentence).The probability of generating every utterance per speaker was separately computed based on each of HMM1s, HMM2s, and HMM3s using Viterbi decoding algorithm.For each one of these three models, the model with the highest probability was chosen as the output of speaker identification as given in the following formula, a.In HMM1s, (11) where O is the observation vector or sequence that belongs to the unknown speaker and v HMM1s is the acoustic firstorder hidden Markov model of the v th speaker.b.In HMM2s,
v HMM1s v O P max arg * V 1 40 v HMM2s v O P max arg * V 1 40 (12)
where v HMM2s is the acoustic second-order hidden Markov model of the v th speaker.c.In HMM3s,
v HMM3s v O P max arg * V 1 40 (13)
where v HMM3s is the acoustic third-order hidden Markov model of the v th speaker.
VII. RESULTS AND DISCUSSION
In this work, new proposed models called HMM3s have been employed as classifiers in each of neutral and shouted talking enviroments.These classifiers have been tested on our collected speech databae.Table I summarizes speaker identification performance in neutral and shouted talking environments using the collected database based on each of HMM3s, HMM2s, and HMM1s.This table evidently shows that speaker identification performance in neutral talking environments has been insignificantly improved based on HMM3s compared to that based on each of HMM2s and HMM1s.In neutral talking environments, the average improvement rate of speaker identification performance based on HMM3s compared to that based on HMM2s and HMM1s is 1.6% and 3.3%, respectively.On the other hand, the table apparently illustrates that the performance in shouted talking environments has been significantly enhanced based on HMM3s compared to that based on each of HMM2s and HMM1s.The average improvement rate of speaker identification performance in shouted talking environments based on HMM3s compared to that based on HMM2s and HMM1s is 11.3% and 166.7%, respectively.
A statistical significance test has been performed to show whether speaker identification performance differences (speaker identification performance based on HMM3s and that based on each of HMM2s and HMM1s) are real or simply due to statistical fluctuations.The statistical significance test has been carried out based on the Student's t Distribution test as given by the following formula,
pooled 2 1 1,2 SD x x t (14)
where 1
x is the mean of the first sample of size n, 2 x is the mean of the second sample of the same size, and SDpooled is the pooled standard deviation of the two samples given as,
n SD SD SD 2 2 2 1 pooled (15)
where SD 1 is the standard deviation of the first sample of size n and SD 2 is the standard deviation of the second sample of the same size.
Based on Table I and the last two equations, the calculated t values between HMM3s and each of HMM2s and HMM1s in neutral and shouted talking environments using the collected database are given in Table II.Each calculated t value in the neutral talking environments is smaller than the tabulated critical value t 0.05 = 1.645 at 0.05 significant level, while each calculated t value in the shouted talking environments is greater than t 0.05 = 1.645.Therefore, the conclusion that can be drawn in this experiment is that HMM3s insignificantly improve speaker identification performance in neutral talking environments compared to each of HMM2s and HMM1s.It can also be concluded in this experiment that speaker identification performance in shouted talking environments based on HMM3s outperforms that based on each of HMM2s and HMM1s.This significant enhancement in shouted talking environments may be attributed to the fact that in HMM3s the state-transition probability at time t+1 depends on the states of the Markov chain at times t, t-1, and t-2.Therefore, the underlying state sequence in HMM3s is a third-order Markov chain where the stochastic process is specified by a 4-D matrix.On the other hand, in HMM2s, the statetransition probability at time t+1 depends on the states of the Markov chain at times t and t-1.Therefore, the underlying state sequence in HMM2s is a second-order Markov chain where the stochastic process is defined by a 3-D matrix.In HMM1s, it is assumed that the statetransition probability at time t+1 depends only on the state of the Markov chain at time t.Therefore, in HMM1s the underlying state sequence is a first-order Markov chain where the stochastic process is expressed by a 2-D matrix.Hence, the stochastic process that is specified by a 4-D matrix gives higher speaker recognition performance than that specified by either a 3-D matrix or a 2-D matrix.
In this work, the achieved speaker identification performance based on HMM3s in each of neutral and shouted talking environments is higher than that reported in previous studies [9], [11].Raja and Dandapat [9] attained 28.57% as an average speaker identification performance in angry talking environments of SUSAS database.Shahin [11] reported an average speaker identification performance of 59.0% in shouted talking environments (collected database) based on HMM2s.
Two extensive experiments have been carried out in this work to evaluate the achieved results of speaker identification performance in each of neutral and shouted talking environments based on HMM3s.The two experiments are:
1. Experiment 1: HMM3s have been assessed on the SUSAS database.This database does not contain shouted talking condition.Since shouted talking condition can not be entirely separated from angry talking condition in real life, HMM3s have been used as classifiers to evaluate speaker identification in angry talking environments.In this experiment, only neutral and angry talking conditions of SUSAS database have been used to assess HMM3s.Table III summarizes speaker identification performance based on each of HMM3s, HMM2s, and HMM1s in neutral and angry talking conditions using such database.The results of this experiment show that HMM3s are superior to each of HMM2s and HMM1s in significantly improving speaker identification performance in angry talking condition.Table IV demonstrates calculated t values between HMM3s and each of HMM2s and HMM1s in the two talking conditions using this database.Table IV evidently shows that HMM3s significantly enhance speaker identification performance compared to each of HMM2s and HMM1s in angry talking condition, while HMM3s insignificantly improve the performance compared to each of HMM2s and HMM1s in neutral talking condition using this database.
2. Experiment 2: An informal subjective assessment of HMM3s using the collected speech database has been performed with ten nonprofessional listeners (human judges).A total of 640 utterances (40 speakers × 2 talking environments × 8 sentences) have been used in this assessment.During this evaluation, each listener was separately asked to identify the unknown speaker in each of neutral and shouted talking environments for every test utterance.The average speaker identification performance in neutral and shouted talking environments based on the subjective assessment is 93.4% and 77.1%, respectively.These averages are close to the averages obtained in the present work using the same database based on HMM3s.
VIII. CONCLUDING REMARKS
In this work, HMM3s have been proposed, implemented, and evaluated in each of neutral and shouted/angry talking environments as classifiers.Some experiments have been performed to assess these classifiers in the two talking environments.The proposed classifiers have been tested on two distinct speech databases: our collected database and SUSAS database.HMM3s have proven to be superior to each of HMM2s and HMM1s for speaker identification in shouted/angry talking environments, while the proposed models perform slightly better than each of HMM2s and HMM1s in neutral talking environments.
There are some limitations in this work.First, a naïve implementation of the recursion for the computations of and in HMM3s necessitates on the order of N 4 T (N is the number of states and T is the utterance length) operations, compared to N 3 T and N 2 T operations in HMM2s and HMM1s, respectively.Second, the number of speakers available in SUSAS database is limited to 9. Third, all the 9 speakers available in SUSAS database are of the same gender (male).Finally, speaker identification performance in shouted/angry talking environments based on HMM3s is imperfect.
.
Givenasequenceofobservedvectors,O 1 O,2 O,..., O T,the joint state-output probability isdefined as:
Table I
I
Speaker identification performance in neutral and shouted talking environments using the collected
database based on each of HMM3s, HMM2s, and HMM1sModelsGenderNeutral talking environments Shouted talking environmentsMale94%63%HMM3sFemale95%65%Average94.5%64%Male92%57%HMM2sFemale94%58%Average93%57.5%Male92%23%HMM1sFemale91%25%Average91.5%24%Table IICalculated t values between HMM3s and each of HMM2s and HMM1s in neutral and shoutedtalking environments using the collected databaseCalculated t value (t 1,2 )Neutral talking environmentsShouted talking environmentstHMM3s, HMM2s1.0181.781tHMM3s, HMM1s1.3451.822Table IIISpeaker identification performance based on each of HMM3s, HMM2s, and HMM1s in neutral andangry talking conditions using SUSAS databaseModelsNeutral talking conditionAngry talking conditionHMM3s95%65.5%HMM2s93.5%58.5%HMM1s92%27%Table IVCalculated t values between HMM3s and each of HMM2s and HMM1s in neutral and angry talkingconditions using SUSAS databaseCalculated t value (t 1,2 )Neutral talking conditionAngry talking conditiont HMM3s, HMM2s1.0421.756t HMM3s, HMM1s1.2361.896
Speaker-dependent-feature-extraction, recognition and processing techniques. S Furui, Speech Communication. 10March 1991
Speaker recognition using neural networks and conventional classifiers. K R Farrell, R J Mammone, K T Assaleh, IEEE Transactions on Speech and Audio Processing. 2January 1994
Speaker recognition using hidden Markov models, dynamic time warping and vector quantization. K Yu, J Mason, J Oglesby, IEE Proceedings on Vision, Image and Signal Processing. October 1995142
Automatic speaker recognition using Gaussian mixture speaker models. D A Reynolds, The Lincoln Laboratory Journal. 821995
Analysis of the glottal excitation of emotionally styled and stressed speech. K E Cummings, M A Clements, Journal of the Acoustical Society of America. 981July 1995
A comparative study of traditional and newly proposed features for recognition of speech under stress. S E Bou-Ghazale, J H L Hansen, IEEE Transactions on Speech and Audio Processing. 8
Nonlinear feature based classification of speech under stress. G Zhou, J H L Hansen, J F Kaiser, IEEE Transactions on Speech and Audio Processing. 93March 2001
Cepstral domain talker stress compensation for robust speech recognition. Y Chen, IEEE Transactions on Acoustics, Speech and Signal Processing. 364April 1988
Speaker recognition under stressed condition. G S Raja, S Dandapat, International Journal of Speech Technology. 132010
Analysis and classification of speech mode: whispered through shouted. C Zhang, J H L Hansen, 2007INTERSPEECH 2007-ICSLP
Improving speaker identification performance under the shouted talking condition using the second-order hidden Markov models. I Shahin, EURASIP Journal on Applied Signal Processing. 54March 2005
Enhancing speaker identification performance under the shouted talking condition using second-order circular hidden Markov models. I Shahin, Speech Communication. 488August 2006
Speaker identification in the shouted environment using suprasegmental hidden Markov models. I Shahin, Signal Processing Journal. 8811November 2008
Employing second-order circular suprasegmental hidden Markov models to enhance speaker identification performance in shouted talking environments. I Shahin, 10.1155/2010/862138EURASIP Journal on Audio, Speech, and Music Processing. 20102010
Isolated word recognition using Markov chain models. J Dai, IEEE Transactions on Speech and Audio Processing Journal. 3
A tutorial on hidden Markov models and selected applications in speech recognition. L R Rabiner, Proceedings of IEEE. 77
Automatic word recognition based on second-order hidden Markov models. J F Mari, J P Haton, A Kriouile, IEEE Transactions on Speech and Audio Processing. 51January 1997
A second-order HMM for high performance word and phoneme-based continuous speech recognition. J F Mari, F D Fohr, J C Junqua, Proceedings IEEE International Conference on Acoustics Speech and Signal Processing. IEEE International Conference on Acoustics Speech and Signal ProcessingAtlanta, USAMay 19961
The impact of speech under stress on military speech technology. J H L Hansen, C Swail, A J South, R K Moore, H Steeneken, E J Cupples, T Anderson, C R A Vloeberghs, I Trancoso, P Verlinde, IST)TP/ 5IST/TG-01NATO Research & Technology Organization RTO-TR-10. 3232000
Emotion recognition from Assamese speeches using MFCC features and GMM classifier. A B Kandali, A Routray, T K Basu, Proc. IEEE Region 10 Conference TENCON 2008. IEEE Region 10 Conference TENCON 2008Hyderabad, IndiaNovember 2008
Modulation spectral features for robust far-field speaker identification. T H Falk, W Y Chan, IEEE Transactions on Audio, Speech and Language Processing. 181January 2010
| [
-0.1960969716310501,
-0.018914680927991867,
-0.048117510974407196,
-0.20714761316776276,
0.05463748425245285,
0.1343396157026291,
0.14029669761657715,
-0.17700083553791046,
0.233843132853508,
-0.07907571643590927,
-0.0511784590780735,
-0.10617034137248993,
0.15265904366970062,
-0.007787546... |
2021
Journal of Physics: Conference Series
175111003202110.1088/1742-6596/1751/1/011003Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd
Figure 2
2Keynote Speaker by Prof Harith, Prof John Hendri, and Prof Ivandini
Figure 3 Figure 4
34Speech by the Dean of Faculty of Mathematics and Natural Sciences, UNILA
Figure 7 Closing Speech by Heri Satria
| [
-0.20138019323349,
-0.059752706438302994,
0.0527118444442749,
0.16882644593715668,
0.002563583431765437,
-0.01892542839050293,
-0.07375219464302063,
0.06717421859502792,
0.06827674061059952,
0.023065615445375443,
-0.02504740282893181,
-0.043302491307258606,
-0.06384212523698807,
-0.0353370... |
Access of information, control, and benefits for women in beef cattle farming households in Lakitan Utara Nagari, Pesisir Selatan Regency
S Andarwati andar_siti@ugm.ac.id
Social Economic Departement
Animal Husbandry Faculty
Gadjah Mada University
YogyakartaIndonesia
B Guntoro
Social Economic Departement
Animal Husbandry Faculty
Gadjah Mada University
YogyakartaIndonesia
M Fajri
Social Economic Departement
Animal Husbandry Faculty
Gadjah Mada University
YogyakartaIndonesia
Access of information, control, and benefits for women in beef cattle farming households in Lakitan Utara Nagari, Pesisir Selatan Regency
823E99279A61F353D2A5C442FCD82F9A10.1088/1755-1315/1341/1/012101access of informationcontrolbenefits for womenbeef cattle farming households
The objective of this study was to analyze the access of information, control, and benefits for women in beef cattle farming households in Lakitan Utara Nagari, Pesisir Selatan Regency, Sumatera Barat Province.This study employed a descriptive approach using survey and involved 100 families.The survey comprised of questionnaires and interviews.Results showed that women gained access of information mostly from their farming counterparts.They also have the access to and control for decision making on resources and livestock care.These women also enjoyed the benefits from farming beef cattle.
Introduction
One of the objectives in the sustainable development agenda is to attain gender equality.The Indonesian Central Government formulates National Family Farming Action Plans that encompass interminable family farming, gender equality, increased capacity of farmers organizations, and increased farmers welfare.This program is inscribed in the Strategic Plans of the Agriculture Ministry 2020-2024.Furthermore, a Presidential Instruction states that the mainstreaming gender in the national development should reduce the difference between genders and consequently create equality.This Instruction further details the gender equality as a condition in which men and women have the same opportunities as well as human rights to achieve the same roles in various fields, such as politics, social, culture, economy, and so on.
The livestock farming employs many women.Female workers are needed in this field because it requires patience and tenacity, traits that many women possess [1].However, there are still issues of gender inequality in animal husbandry, in which men still dominate the access and control of resources and benefits [2].Improving income and welfare in cattle farming families can be achieved by increasing the roles of women in livestock production, as well as recognition of women's rights on access and control [3].
Access to information on animal husbandry is very important for both men and women who are involved in this vocation.It is especially important for providing a greater access to information for women because it can significantly improve the participation and ability of woman farmers in maintaining the food security in their families [4].The ignorance and inability of woman farmers in accessing current information in agriculture often inhibit their advancement and, therefore, contribution to their families' food security [5].
Women have varied opportunities (access) and power (control or decision making) [6].Gender issues in Indonesia are related to socioculture and traditions that have developed in each community.For example, men still dominate the access to and control of resources and benefits in some places in Java and Papua [7].Meanwhile, the people of Pesisir Selatan Regency, Sumatera Barat Province, are members of the largest matrilineal society in the world, known as Minangkabau.However, there is an IOP Publishing doi:10.1088/1755-1315/1341/1/012101 2 argument circulating in the community that matrilineal values are not fully observed, and therefore, gender equality has not been achieved in the Minangkabau society [8].
This study was carried out to determine the extent of access to information, control, and benefits that woman farmers faced in Lakitan Utara Nagari, Pesisir Selatan Regency.
Methodology
The study took place in Lakitan Utara Nagari, Lengayang Subdistrict, Pesisir Selatan Regency, Sumatera Barat Province, from December 2021 to February 2022.Nagari is an administrative level just below subdistrict.There were 100 families participating in this study, as well as some collaborating partners.A descriptive approach was employed at several stages.The first stage was determining the location using the purposive sampling method.The next stage was asking the chosen participants to fill out the questionnaires as well as interviewing them.The analytical stage involved categorizing the aspects into access to information, control, and benefits that the woman farmers experienced in their households.The data collected could be grouped into primary, from questionnaires and interviews, and secondary, from related sources.
Results and discussion
Characteristics of respondents
The characteristics that were recorded from these woman farmers were age, formal education, and length of experience in raising beef cattle.
Age
The distribution of ages among these woman farmers was 15 -29 y.o.(6%), 30 -44 y.o.(47%), 45 -59 y.o.(41%), 60 -64 y.o.(5%), and > 64 y.o.(1%).Badan Pusat Statistik (BPS/Central Bureau of Statistics) defines productive age to be between 15 and 65 years old, while non-productive age to be less than 15 and greater than 65 years old.The results of this study indicated that 99% participants fall into the productive age category.Age significantly influences the intensity in carrying out business endeavors [9].Productive age is important for farmers to accomplish their business goals because at this stage they are able to coordinate and take effective steps to improve their ventures [10].
Formal education
The formal education that these participants received could be grouped into elementary at 33%, secondary at 23%, high school at 42%, and 2% completed baccalaureate degrees.The length of formal education could predict the ability to learn, in which the higher one completes their education, the easier they understand new information [11].
Experience in animal husbandry
The majority woman farmers had experienced more than 15 years of cattle raising at 54%.The next largest group is 1 -5 year experience at 23 %, followed by 6 -10 year experience at 18%, and there were only 5% at 11 -15 year experience.Farmers with longer working experience would show better skill and attitude in managing their livestock [12].
Access to information
Access to information was determined from how easy/hard the farmers accessed information, which facilitated the management of their cattle, from various sources.This information could include procuring starter animals to selling these animals and everything in between.The sources were categorized into related government bureaus, other farmers, television, newspaper, radio, social media, sales representatives, higher education, private businesses and/or non-governmental organizations (Table 1 The information sources that these women encountered were from other farmers, government bureau, television, and social media.All woman farmers claimed to receive information from other farmers.A significant number (95%) of them also obtained information from the livestock bureau, through the artificial insemination technicians.Meanwhile, social media and television contributed information to small numbers of participants at 9% and 3% respectively.Information on livestock management is important for farmers to carry out their tasks properly.Ease of access to information can support farmers to improve their knowledge and skill in animal husbandry.
Extension agents from related government bureaus are needed in their roles as conductors of information to provide important insights that support the farmers in carrying out their business.This information could be related to management of livestock business, good methods in animal care, disease control, as well as innovations in animal husbandry.Routine guiding and counseling can certainly help farmers in managing their livestock, improving their welfare, and creating sustainable businesses.This guiding and counseling activity can further empower the community members because it creates effective and efficient farmers [13].
The aspect of access to and control of resources and management in beef farming households
Women (wives) and men (husbands) have the same access and control on equipment, calf procurement, cattle sale, and finance management (Table 2).However, for access and control of farmland, women have a stronger position than men.This is the result of their matrilineal culture, in which the ownership of family land is inherited through the wives' lines.None the less, husbands still have a control on the resources of their families' lands.But when the land is not from family inheritance, for example a new purchase, wives and husbands have the same access and control.Woman farmers have the same access and control as their husbands for the care of their livestock (Table 2).These maintenance activities include feeding, herding, pen cleaning and caring for sick animals.Woman farmers have the ability to assume a full role in the decision making in beef cattle farming at small scales [14].Women of Lakitan Utara Nagari are involved in every decision making because this nagari is a part of Minangkabau traditional region in which matrilineal customs are still parts of their culture.Theoritically, matrilineal values in Minangkabau culture reinforce women's position in society, which in turn strengthens one of the national development goals in gender equality.These matrilineal norms give Minangkabau women advantageous positions in owning and managing properties and economic resources in families, as well as being able to participate and have rights in decision making [15].
Aspect of benefits in household beef cattle production
The aspect of benefits is defined as family activities having to bring equal benefits to all family members [16].The benefit aspect measured in this study was whether the animal husbandry venture brought benefits to the farmers' families.Results showed that husbands and wives gained benefits from their beef cattle farming.In general, beef cattle farming provided assistance in fulfilling daily needs, children's education, health costs, home renovations, as well as business capital.These results support the finding of a previous study [17].
Conclusion
Woman farmers in Lakitan Utara Nagari had access to information mostly from their farming counterparts.They also possessed access to and control of resources and care for their livestock.Benefits from family beef cattle operations were also gained by these women.
Table 1 .
1
). Information accessability for woman cattle farmers in Lakitan Utara Nagari
IOP Publishingdoi:10.1088/1755-1315/1341/1/012101
Table 2 .
2
Aspect of access to and control of resources and management in beef farming households
Access and controlAccessControlof resourcesWomanManWomanManFarmlandEquipmentCalf procurementCattle saleFinance managementAccess and controlAccessControlof cattle care
AcknowledgementAuthors wish to express gratitude for the support from Gadjah Mada University through the Recognition Program for Final Assignment.
Peran Serta Wanita Peternak Sapi Perah dalam Meningkatkan Taraf Hidup Keluarga. M Lestariningsih, B Basuki, E Endang, 10.24034/j25485024.y2008.v12.i1.236Ekuitas (Jurnal Ekonomi Dan Keuangan). 1212018
Women, gender equality in livestock development : case study from Papuan and Central Java. Sustainable Animal Production for Better Human Welfare and Environment in International Seminar on Animal Industry. T Sumarti, A M Fuah, 10.24034/j25485024.y2008.v12.i1.2362015. 2015 Sep 17-18
Faculty of Animal Science IPB. Bogor, ID)
The Role of Livestock in Developing Communities : Enhancing Multifunctionality. W Bayer, B Letty, 2010Bloemfontein (ZA) : university of the Free State
Partisipasi Woman Tani dalam Mencapai Ketahanan Pangan Rumah Tangga. Kasus di Kabupaten Lombok Timur Provinsi Nusa Tenggara Barat. Bogor2015
Relasi Gender dan Ketahanan Pangan. di dalam: Merevolusi Revolusi Hijau. A Hubeis, 2012IPB PressBogor (ID
Usahatani yang Berkeadilan Gender dan Menguntungkan. E P Manginsela, ELSJE Pauline Manginsela. Agri-Sosio Ekonomi Unsrat. 2017
Sustainable Animal Production for Better Human Welfare and Environment in International Seminar on Animal Industry. T Sumarti, A M Fuah, Faculty of Animal Science IPB. Bogor (ID2015. 2015 Sep 17-18Women, gender equality in livestock development : case study from Papuan and Central Java
Minangkabau matriliny and gender equality: Cultural contribution to sustainable development goal. P E Nasir, A Halim, T Herida, S Cory, A F Sinulingga, A Mukhti, B Hidayat, F Gib, 10.25077/ajis.10.1.16-33.20212021
Analisis usaha ternak indukan sapi peranakan Simental di Kecamatan Patean Kabupaten Kendal. R S Prayitno, Agromedia. 3612018
Potensi pengembangan peternakan sapi potong di kecamatan tanjung bintang kabupaten lampung selatan. H Y Prawira, R Muhtarudin, Sutrisna, Jurnal ilmiah peternakan terpadu. 342015. November 2015
Keberhasilan inseminasi buatan (IB) pada Sapi Aceh menggunakan Semen Beku Sapi Bali, Simental, dan Limosin di Kecamatan Mesjid Raya Kabupaten Aceh Besar. N B Tarmizi, D Dasrul Dan, G Riady, JIMVET. 232018
Tingkat keberhasilan inseminasi buatan (IB) pada peternakan sapi potong di Kelurahan Kalampangan Kecamatan Sabangau Kota Palangka Raya. K Kastalani, H Torang Dan, A Kurniawan, Jurnal Ilmu Hewani Tropika. 822019
Peranan penyuluh dalam penerapan paket teknologi pada usaha peternakan kerbau (Studi kasus pada kelompok ternak "Kerbau Antrada. Dan A Ediset, Anas, Jurnal Peternakan Indonesia. 1512013Kecamatan Koto Baru Kabupaten Dharmasraya)
. E Ramon, Z Efendi, E Fauzi, N Deviniati, A Ishak, W A Wulandari, Jurnal Inspirasi Peternakan. Peranan Wanita Tani Dalam Usaha Ternak Sapi Potong (Kasus Kelompok Tani Sri Rejeki, Desa Jayakarta, Kec. Talang Empat, Kab. Bengkulu Tengah122021
Pergeseran citra wanita minangkabau: dari konsepsi ideal-tradisional ke realitas. kafa'ah. Erianjoni, Jurnal Ilmiah Kajian Gender. 1
Gender dan Keluarga: Konsep dan Realita di Indonesia. H Puspitawati, 2012PT IPB PressBogor
Peran anggota keluarga pada usaha pemeliharaan ternak sapi potong di Kelurahan Makalonsouw Kecamatan Tondano Timur. S Takasenserang, S O B Lombogia, J A Malingkas, A A Sajow, 10.35792/zot.41.1.2021.32007Zootec. 411812021
| [
-0.033960312604904175,
0.01598959229886532,
-0.07991507649421692,
0.03934653103351593,
-0.08693253248929977,
0.03147762268781662,
-0.07936421036720276,
0.040358610451221466,
-0.03359568119049072,
0.07094204425811768,
0.13645564019680023,
-0.0932389497756958,
-0.06528205424547195,
-0.056039... |
Alternative Procedure to Screening a Large Number of Plates for a Low Number of Mutants'
Jan. 1974
Dennis C Westhoff
Department of Dairy Science and Food Science Curriculum
University of Maryland
20742College Park, Maryland
Alternative Procedure to Screening a Large Number of Plates for a Low Number of Mutants'
APPLIED MICROBIOLOGY
271Jan. 1974Received for publication 21 September 1973
An apparatus is described in which tygon tubing replaces the use of petri dishes in the screening of a large volume of agar for an expected low number of mutants.
By employing conditions for optimal mutation of Streptococcus lactis as previously described (2), we were attempting to isolate mutants which would form colonies on lactic agar (1) within 48 h at 32 C when the medium was adjusted to pH 5.1. Tempered lactic agar was inoculated with the mutant population and then poured into a large number (200 to 300) of petri dishes and incubated at 32 C. After 24 h of incubation, the plates were removed and observed for colony formation at 6-h intervals up to 48 h. This required removing several hundred plates from the incubator, placing them on a Quebec colony counter, observing for any colony formation, and then replacing the plates in the incubator. In an attempt to eliminate this time-consuming task, we have designed the apparatus shown in Fig. 1. It functions much like a film editor in that by turning the two plexiglass wheels, tubing containing inoculated lactic agar can be viewed either by a low-power dissecting microscope or with the naked eye and colonies detected. The desired colonies can easily be isolated by scrubbing that area of the tubing with a quatincture (0.1% hyamine in 70% ethanol) and then piercing the wall with a sterile 18-guage hypodermic needle and fishing the colony out. The section of the tubing pierced cannot be reused. We usually just removed that section and rejoined the tubing with a connector. A smaller gauge needle might not damage tubing, but by using an 18-gauge needle, the colony is retained somewhat inside the needle. To eliminate any other possible contamination removed with the needle, the culture can then be streaked onto the original isolation medium for confirmation.
The actual dimensions are not critical. The ' Scientific article no. A1938, contribution no. 4862 of the Maryland Agricultural Experiment Station, Department of Dairy Science. apparatus depicted in Fig. 1 is made entirely of 0.5-inch (1.27 cm) plexiglass. The two drums for winding the tubing are 30.5 cm in diameter, with the space between the wheels being 15 cm. The complete base plate is 30.5 by 61 cm.
A more detailed description of the operation is as follows. Two 50-ft (15.24 m) sections of 5A6-inch (0.794-cm) outer diameter tygon flexible tubing (a plasticized polyvinyl chloride tubing) were joined together with a QD connector (Mallinckrodt, New York). The two open ends of the resulting 100 ft (30.48 m) of tubing were cemented with epoxy glue to predrilled holes in each of the wheels via a QD connector. The tubing was sterilized by attaching another piece of similar tubing with connector (labeled as B in Fig. 1) to a reservoir of quatincture and drawing approximately 2 liters of quatincture through the tubing by attaching flask A to an aspirator. The quatincture was followed by 4 liters of sterile distilled water at 90 to 95 C. Lactic agar (pH 5.1) was tempered to 43 C, inoculated with the mutant population, and immediately drawn into the tubing in a similar fashion. The agar was permitted to solidify within the tubing before the apparatus was placed in a 32-C incubator. Flexibility of the tubing is maintained when the agar solidifies. The two pieces of tubing needed for sterilizing and filling the tubing with agar, that is, the tubing labeled B in Fig. 1 and the tubing from the small vacuum flask labeled A in Fig. 1, were removed before incubation, and the connector was simply covered with tape. After the desired intervals of incubation, the apparatus was removed from the incubator and the wheels were turned to permit viewing of the entire length of tubing. In most cases, colonies were detected with the naked eye; however, to confirm the presence of a colony and for isolation, the low-power dissecting microscope was used, as shown in Fig. 1. The agar can be removed by slowly pressurizing tubing B (Fig. 1) and pushing the agar out into a container placed at outlet A. The tubing can be reused repeatedly.
The apparatus as described has proven to be quite successful for our purposes, and we have isolated mutants. By employing longer lengths of tubing (these wheels will hold about 300 ft (91.44 m) of 5A6 O.D. tubing), we can incorporate about 2.5 liters of lactic agar, which would be equivalent to 200 petri dishes. In addition, the time involved in handling plates has been eliminated. The apparatus has also made it practical to remove the inoculated agar at more frequent time intervals from the incubator in order to detect the first visible colony.
Any technique employing a large number of plates in the screening of an expected low number of mutants would probably benefit from the use of this apparatus. Problems may be encountered with highly motile organisms (spreading in tube) or with strict anaerobes (02 permeability of the tubing). We have attempted neither, but for the latter (anaerobes), tubing other than tygon, or possibly the addition of a reducing agent to the medium, might be more suitable. We have used the apparatus for other purposes; for example, by inoculating the agar with more than one culture we have been able to observe inhibitory reactions between cultures by looking for zones of inhibition within the tubing. In this way, large populations can be screened.
FIG. 1 .
1Apparatus used to wind tygon tubing containing inoculated agar. A, Filtering flask attached to aspirator; B, tubing connection for sterilizing and filling with agar.
LITERATURE CITED 1. Elliker, P. R., A. W. Anderson, and G. Hannesson. 1956. An agar culture medium for lactic acid streptococci and lactobacilli. J. Dairy Sci. 39:1611-1612. 2. Westhoff, D. C., and P. Adams. 1972. Survival of Streptococcus lactis and Leuconostoc citrouorum following exposure to N-methyl-N-nitro-N-nitrosoguanidine. J. Dairy Sci. 55:865-866. STATEMElff OF OWE* R6W. FI-ESAT AND ClftV-sT" A13 S-rAt, .W. Worthingt, D.9. 200NW0 .hit 00 M YI. P. Ury t, D Pt. of D.try S.A.-, U.Ivo.Lty of UlinoI., Urba, Ullno. 61t Robert A. D y, 40LU Pilcko Rod, Silve Spmtg, Drylond 209028=
_
õ~~~~~~~~~~~1
13
11i657s
_rg7-gS,~~~~~~~~NNE
N
X TOTES 0 Cod P-no Of I_
1975d
11657
*~~~~~~~~~~~~~13 11oc.
A-i
e-4ty
U
W. W.hg-
NOTES
| [
-0.05181217938661575,
-0.1131829172372818,
-0.07112248241901398,
-0.1412850320339203,
-0.04575243592262268,
-0.07251383364200592,
-0.06696617603302002,
0.12757635116577148,
-0.04978564381599426,
0.09352847188711166,
0.11648732423782349,
-0.12737390398979187,
-0.007962943986058235,
0.051194... |
* * * * * * * * * * * * *
* * * * * * * * * * * * *
Supplementary Figure 1: Correlations between measured brain pathologies and CA and vascular risk factors. a) This plot summarizes the Spearman rank-based correlation between cerebral atherosclerosis and microinfarcts, gross infarcts, β-amyloid, tangles, cerebral amyloid angiopathy (CAA), Lewy body, hippocampal sclerosis, and TDP-43 n the discovery dataset (N=375). Significance was based on adjusted p value less than 0.05 and noted with an asterisk. b) This plot summarizes the Pearson correlation between cerebral atherosclerosis and the mean plasma low-density lipoprotein (LDL; N=373), mean triglyceride (TG; N=374), and mean high-density lipoprotein (HDL; N=374) levels averaged across all available years of follow-up. Significance was based on an unadjusted p-value less than 0.05 and noted with the asterisk.
proteins associated with cerebral atherosclerosis after adjusting for the 7 other measured pathologies but not gross infarcts at proteome-wide adjusted p <0.05 in the discovery dataset. These 237 proteins were divided into higher-abundance and lower-abundance proteins in cerebral atherosclerosis for the gene set enrichment analysis. Enrichment was determined using a one-sided Z test.
Supplementary Figure 3:
This figure summarizes the gene set enrichment analysis of the 142 proteins associated with cerebral atherosclerosis after adjusting for the 7 other measured pathologies but not microinfarcts at proteome-wide adjusted p <0.05 in the discovery dataset. These 142 proteins were divided into higher-abundance and lower-abundance proteins for the gene set enrichment analysis. Enrichment was determined using a one-sided Z test. Figure 4: This figure presents the gene set enrichment analysis of the 856 proteins associated with cognitive diagnosis at proteome-wide adjusted p <0.05 in the discovery dataset. These 856 proteins were divided into higher-abundance and lower-abundance proteins for the gene set enrichment analysis. Enrichment was determined using a one-sided Z test.
Supplementary
Supplementary Figure 5:
This figure summarizes the gene set enrichment analysis of the 23 proteins associated with β-amyloid after adjusting for the 8 other measured pathologies at proteomewide adjusted p <0.05 in the discovery dataset. Enrichment was determined using a one-sided Z test.
Supplementary Figure 6: This figure summarizes the gene set enrichment analysis of the 244 proteins associated with neurofibrillary tangles after adjusting for sex, age at death, cell type composition, and the eight other measured pathologies at proteome-wide adjusted p <0.05 in the discovery dataset. These 244 proteins were divided into higher-abundance and lower-abundance proteins in tangles for the gene set enrichment analysis. Enrichment was determined using a onesided Z test.
Supplementary Figure 7:
Protein-protein interactions among the 23 proteins differentially expressed in both cerebral atherosclerosis and AD at proteome-wide adjusted p<0.05 and the proteins composing the protein co-expression modules 3 and 9, both of which were also associated with cerebral atherosclerosis and AD. DEPs refer to the 23 proteins differentially expressed in both atherosclerosis and AD. Sixty percent of the proteins in module 9 and 58% of the proteins in module 3 have physical interactions. Interactions were based on BioGRID database (v3.5.179).
Supplementary
Figure 2 :
2This figure summarizes the gene set enrichment analysis of the 237
table 3 :
3Characteristics of the 236 ROS/MAP subjects with ex-vivo imaging data # p-values for comparing the 236 subjects with ex-vivo imaging data with the 391 subjects with proteomic data using two-sided Fisher exact test for categorical variables and two-sided t-test for continuous variables.Characteristic
N
Percent
p-value #
Sex
0.468
Female
Male
172
64
72.9
27.1
Cognitive diagnosis at baseline
Normal cognition
Mild cognitive impairment
236
0
100.0
0.0
1.000
Cognitive diagnosis at death
Normal cognition
Mild cognitive impairment
Alzheimer's dementia
Other dementia
74
92
64
6
31.4
39.0
27.1
2.5
0.993
Mean [SD]
Median
Range
Age at enrollment
80.3 [6.4]
80.6
[59.0-96.3]
0.268
Age at death
90.2 [5.8]
90.0
[65.9-103.6]
0.054
Education
15.6 [3.6]
16.0
[5.0-27.0]
0.573
Number of follow-up years
9.8 [4.5]
9.0
[2.0-21.0]
0.396
Post-mortem interval (PMI)
8.2 [5.1]
6.7
[0.0-32.6]
0.715
Vascular risk factors
1.2 [0.89]
1.0
[0.0-3.0]
0.536
N
Percent
Brain infarcts
Gross infarct (Present)
76
32.2
1.000
Microinfarct (Present)
71
30.1
0.717
Hippocampal sclerosis (Present)
22
9.3
0.451
Lewy Body (Present)
60
25.4
0.929
TDP-43 (Present)
107
45.3
0.801
Mean [SD]
Median
Range
Cerebral atherosclerosis
1.1 [0.8]
1.0
[0.0-3.0]
0.727
Alzheimer's disease pathology
β-Amyloid
6.0 [5.0]
5.7
[0.0-19.9]
0.002
Tangles
5.5 [5.4]
3.8
[0.0-30.5]
0.129
Cerebral amyloid angiopathy
1.1 [0.8]
1.0
[0.0-3.0]
0.671
| [
-0.10478849709033966,
-0.12037371098995209,
-0.10634032636880875,
0.08287718892097473,
0.06577863544225693,
0.015581747516989708,
-0.05569775402545929,
0.16160225868225098,
0.03660459816455841,
-0.003969151992350817,
-0.021786784753203392,
0.0012075258418917656,
-0.06096496433019638,
0.056... |
Published Online July 17, 2020
Published Online July 17, 202010.1148/radiol.2020201544Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. See Online for appendix
Correspondence e68
www.thelancet.com/infection Vol 21 April 2021
These data highlight the potential hypoxic effect of anaemia in COVID-19 fatalities for sickle cell anaemia carriers and for β-thalassaemia carriers. They also indicate that haemochromatosis type 1 might confer some protection. I
Potential factors linked to high COVID-19 death rates in British minority ethnic groups
The Institute for Fiscal Studies (IFS), in their investigation into the vulnerability of the UK's minority ethnic groups to COVID-19, 1 found hospital deaths in England of Black and south Asian ethnic groups to be inexplicably higher than those of the white British majority after taking into consideration demographic and geographical profiles. However, they did not consider as possible factors the prevalence of sickle cell anaemia or β-thalassaemia. Sickle cell anaemia is inherited in an autosomal recessive pattern, with homozygotes having sickle cell disease and heterozygous carriers having sickle cell trait. Sickle cell trait is asymptomatic. However, it is occasionally associated with sudden death induced by severe hypoxia. Hypoxaemia is a complication of Another complication of COVID-19 is pulmonary embolism: in one study, 3 23% of patients with severe clinical features of COVID-19 had acute pulmonary embolism. People who have sickle cell trait have twice the risk of pulmonary embolism compared with the general population. 4 The relative frequency of sickle cell trait is higher in Black ethnic groups than in the white ethnic majority in the UK (appendix). 5 Of interest, the Black African ethnic group has twice the number of fatalities and frequency of sickle cell trait as does the Black Caribbean group (appendix). 5 Similar to sickle cell anaemia, β-thalassaemia is inherited in an autosomal recessive manner, with heterozygous carriers having β-thalassaemia trait. The relative frequency of β-thalassaemia is higher in the south Asian ethnic groups than in the white ethnic majority (appendix). 5 The only known symptom of β-thalassaemia trait is a tendency for mild anaemia, which could aggravate hypoxaemia due to COVID-19.
The IFS found the white Irish minority to have half the number of fatalities as the white British majority. 1 Haemochromatosis type 1, whose prevalence is higher in the white Irish ethnic group than in the white British ethnic group (appendix), could be having an effect here. 6 The mutation C282Y is inherited in an autosomal recessive pattern. People with the C282Y allele are less likely than those without to be anaemic, homozygotes sometimes having to be regularly bled to reduce their iron overload. 7 Iron-deficiency anaemia could aggravate hypoxaemia due to COVID-19. The prevalence of irondeficiency anaemia has been reported to be lower in white Irish than in white British men (appendix). 8
declare no competing interests. WHO. WHO Global Database on Anaemia. https://www.who.int/vmnis/anaemia/data/ database/countries/gbr_ida.pdf?ua=1 (accessed June 25, 2020).Marion Cook
marion.cook@wanadoo.fr
Échenevex, France
1
Platt L, Warwick R. Are some ethnic groups
more vulnerable to COVID-19 than others?
London: The Institute for Fiscal Studies,
May, 2020.
2
Plasmar RL. Focus on sickle cell research.
New York, NY: Nova Biomedical Books,
2004.
3
Grillet F, Behr J, Calame P, Aubry S,
Delabrousse E. Acute pulmonary embolism
associated with COVID-19 pneumonia
detected by pulmonary CT angiography.
Radiology 2020; published online April 23.
DOI:10.1148/radiol.2020201544.
4 Folsom AR, Tang W, Roetker NS, et al.
Prospective study of sickle cell trait and venous
thromboembolism incidence.
J Thromb Haemost 2015; 13: 2-9.
5
Hickman M, Modell B, Greengross P, et al.
Mapping the presence of sickle cell and beta-
thalassaemia in England: estimating and
validating ethnic-specific rates. Br J Haematol
1999; 104: 860-67.
6 European Association for the Study of the
Liver. EASL clinical practice guidelines for
HFE hemochromatosis. J Hepatol 2010;
53: 3-22.
7
Irish in Britain. Haemochromatosis: the Celtic
disease. https://www.irishinbritain.org/
cmsfiles/Publications/Factsheets/
Haemochromatosis-The-Celtic-Disease.pdf
(accessed June 25, 2020).
8
| [
0.005183789879083633,
0.03960089012980461,
-0.15382041037082672,
0.032168399542570114,
0.030248692259192467,
0.09247496724128723,
0.011883056722581387,
0.1613595187664032,
0.024862732738256454,
0.06078634038567543,
0.039008889347314835,
-0.0600748211145401,
-0.022708572447299957,
-0.003226... |
Turkish Banks and Digitalization: Policy Recommendations from a Qualitative Study
Ahmet Coşkun Yıldırım ahmetcoskunyildirim@yahoo.com
Middle East Technical University
M.ScScience
Turkish Banks and Digitalization: Policy Recommendations from a Qualitative Study
59C7BC06D32265D0E55A415AF33F7B9510.46520/bddkdergisi.841167Received: 05.11.2020 Article Accepted: 01.12.2020DigitalizationTurkish bankingNew regulationsPolicy recommendations JEL Classification: G20G28
Digitalization, as a popular issue in banking, is changing the way of doing business with new business models resulting in a change in employment structure, business development and sales/marketing.Digital platforms utilize operational efficiency, data intensive and even artificial intelligence driven risk management and decision making processes.This change has led to repercussions in organizational structures of banks, sectoral regulations and policy development perspectives.With respect to that, in this study, structured interviews are conducted with seven Turkish top bank managers to provide feedbacks and policy recommendations from the field that support the aforementioned change in banking.
Öz -Türk Bankaları ve Dijitalleşme: Nitel Bir Çalışmadan Elde Edilen Politika Önerileri
Bankacılıkta popüler bir konu olan dijitalleşme yeni iş modelleriyle iş yapma biçimini değiştirmekte, bu yeni iş modelleri istihdam yapısında, iş geliştirme ve satış/pazarlamada değişimlere neden olmaktadır.Dijital platformlar, operasyonel verimlilik, veri yoğun ve hatta yapay zeka odaklı risk yönetimi ve karar verme süreçlerini kullanırlar.Bu değişiklik, bankaların örgütsel yapılarında, sektörel düzenlemelerde ve politika geliştirme perspektiflerinde yankı uyandırmıştır.Bununla ilgili olarak, bu çalışmada, yedi adet bankanın tepe yöneticileri ile yapılandırılmış görüşmeler gerçekleştirilmiş olup, bu görüşmelerle bankacılıkta söz konusu değişimi destekler nitelikte sahadan geri bildirimler ve politika önerileri almak amaçlanmıştır.
Anahtar Kelimeler: Dijitalleşme, Türk bankacılığı, Yeni düzenlemeler, Politika önerileri.JEL Sınıflandırması: G20, G28
Introduction
Technological developments are causing radical changes in many sectors in an increasing pace with important effects of efficiency and profitability resulting in new business models that have changed sector competition and banking paradigm.These developments also provide decreases in costs of operation and increases in customer basis and profitability which result in efficiency, utilization of lesser inputs for producing more outputs in banking (Özel et al., 2017).Banking and finance is the most obvious sector utilizing the benefits resulting from financial innovations.
Oslo Manual defines innovation as the implementation of a new or significantly improved product (good or service), or process, a new marketing method, or a new organizational method in business practices, workplace organization or external relations with reference to product, process, marketing and organizational innovations (Oslo Manual, 2005).Mainly, by using the definition of innovation, it is somehow possible to name significant changes in financial instruments, services, and markets as financial innovation (Comert and Epstein, 2016).These changes may stem from differing characteristics such like cost minimization, operational efficiency, risk management, development of new financial products etc.Definitions of financial innovation vary with reference to their goals, structure of legal framework and market demand and opportunities.Therefore, financial innovation may include product and/or process innovation.
Customers are main drivers of financial innovation with the variety and volume of their demand.The interaction of demand and supply as developing the innovative skills of providers is a historical fact accompanied with the regulatory framework which plays a very crucial role in determining the context, boundaries, and path of financial innovation.With the increasing pace of information and communication technologies, banks and financial institutions can receive prompt feedbacks from the market with reference to changing and differing demand.The constant interaction of all the parties (banks and financial institutions as providers, customers, and regulatory authorities) result in product, process and business model innovation in a certain time.Therefore, the concept of financial innovation has an inclusive content.This inclusiveness has repercussions in considering digitalization and financial innovation as embedded in each other.
Digitalization, as a crucial means of instant banking and finance operations provides ground for a more dynamic demand and supply interaction which results in an increased variety of financial innovations that are product, process and business model innovations.In a sense, digitalization is a major milestone, a paradigm advancing or shifting phenomenon in the context of financial innovation.It is the transformation of banking, finance and money that is witnessed by means of digitalization as a financial innovation.Digitalization by itself is not only a process innovation that provides operational efficiency or a product innovation that provides new financial instruments but it is also a business model innovation due to the fact that digitalization and big data changes the rules of the game.Therefore, digitalization from a macro perspective is to lead more collaboration among actors in the finance and transformation of value creation in a more data analytics-based manner.In sum, during the digitalization process through the emergence of new financial instruments, operational efficiency and product innovation issues came up naturally for the banks.Hence, it is hard to say whether digitalization leads product innovation or not since they emerged simultaneously in the market.However, after the digitalization process existing business models have changed.
With the utilization of digitalization and digital technologies, financial innovation entered a new era defined as the prompt interaction of financial sector companies and customers by means of customer feedbacks, together with increasing collaboration and interaction of financial sector companies.Conventionally, branches are main distribution channels of banking.However, with utilization of technology, alternative distribution channels emerged initially with automated teller machines (ATM).Alternative distribution channels, including mobile devices, digital TVs as well as internet banking, are attractive to banks because of the advantages they provide (e.g.cost cutting, efficiency and better service quality).Digitalization provided a paradigm shift in banking towards intensive utilization of so-called alternative distribution channels.
As the level of digitalization is increasing, codified knowledge base is expanding as a result and this gives way to utilization of various instruments regarding data analytics and decision-making processes.The most prominent of these instruments is artificial intelligence (AI).With utilization of AI and many other instruments, a wide range of sectors benefit from increasing efficiency and profitability that have economic development effects (Accenture, 2017).We see penetration of AI more and more in banking and finance (Yıldırım, 2019).
As a result of digitalization and utilization of AI in banking and finance, value creation is changing in a more efficient way.These issues are repercussion of the strong correlation between financial market development and economic growth.Hence, technological and financial innovations are amongst underlying factors of economic growth.In this respect, financial innovations, as a key concept for an efficient financial system, contribute to economic development with effective channeling of funds for development and by converting the companies to a more efficient and technology intensive business model (Akhavein et al., 2005).
Based on these aforementioned facts, it is understood that, the role of financial innovation, as induced by digitalization, is very important for efficiency and thus improving productivity.Therefore, the pace and quality of its diffusion matters and faster the diffusion of innovation, more immediate the social and economic impact it causes.In this respect, this study is about policy recommendations with regards to changes and scenarios in the future of banking and finance with respect to major business model changes due to digitalization.
The aim of this study is to explore the effects of digitalization and the digitalization-based changes on Turkish Banking Sector (TBS) for the sake of policy development.
Turkey has a great potential for the growing banking technology.According to TURKSTAT, total population is 83,154,997 in the end of 2019 (Turkstat, 2020).The percentage of the population uses 93% of internet and mobile banking.According to Statista, the number of active mobile banking customers increased from 6.7 million to 32 million between 2014 and 2018 in Turkey (Cherowbrier, 2020).As can be seen from these statistics, Turkish digital banking is an interesting case to explore.
From this perspective, the main research question of the study is: "What are the main policy development areas in digitalization process of TBS?" To answer this question in depth, expert views become important to provide an overall picture, for that, structured interviews are conducted with the Vice Presidents and/ or Department Heads of banks in TBS.Vice Presidents like Chief Digital Officers or chief officers responsible for digital transformation processes are interviewed as respondents.Seven representative banks are comprised of private deposit banks, state-owned banks, participation banks, development and investment banks, foreign banks and branches of foreign banks as main types of banks.
The plan of the study is as follows: next section describes the conceptual framework.Following section gives information about the methodology.Namely, research approach, research design, and data collection method are explained in this section.
Further, the grounds of structured interviews, selection of banks and respondents are stated.Section 4 discusses analysis and findings of the study.It is these findings and analysis signaling the unique contribution of this study and paving the ground for the next section that covers discussions and conclusions with policy recommendations.
Conceptual Framework
Main drivers of the digitalization in banking are namely competitive advantages, efficiency increase, prompt respond to customer needs and profitability.Macroeconomic factors, legislative issues, digital technologies, and their implementation in many other sectors lead digitalization to be a compulsory and inevitable process for banking industry (TÜSİAD et al., 2016).In this respect, main banking functions like information gathering, account opening, customer on boarding, day-to-day banking, expanding relationship and ending relationship are covered in the digital framework.By means of digitalization, banks provide a wider range of services in a time saving manner with reduced human involvement and errors.Banks face changes in value creation (Ditshego, 2018) in this context and this results in fast and efficient operation of the finance system and cost minimization of operational processes by substituting machinery and digital processes for people and simple automated processes.
Digital transformation also transforms business towards mobile, flexible, customer-centered base as focused on reshaping customer value propositions and transforming the operating model.In this respect, enhancing products and services for a better customer experience, extending offerings for new value streams, creating new digital capabilities, leveraging information to manage across the organization, integrating and optimizing all digital and physical elements and redefining core elements for a radically reshaped value proposition are important.Hence, business models started to change within banks with digitalization.More efficient back-office operations, internet and mobile banking provided a dynamic platform of interactions and feedbacks between banks and customers.Data-driven business models and analysis became an important part of finance industry.Companies having sound business models, adaptive skills, coherent digitalization strategy, better understanding and expectations of digital transformation of the markets and economy are more likely to avoid costly mistakes and failures and benefit from this process (Davenport, Westerman, 2018).
In this respect, digitalization initially let in-house changes in business models of banks and financial institutions with increasing operational efficiency, internet and mobile distribution channels and decreasing human factor.Therefore, digitalization paved the ground for a more dynamic and changing era of financial sector with more interaction and collaboration of actors emerging as a main determinant of the change of the paradigm.
It is not only collaboration but also roles, business models and interactions between actors that are facing a change, a paradigm shift due to digitalization.From the perspective of traditional banking and legal framework, data privacy and secrecy are main concerns regarding digitalization.However, the pace of digitalization caused a paradigm shift to open banking in a platform-based business approach where interactions and value exchanges are facilitated like in old ancient marketplaces.Therefore, in open banking, data, processes, and business functionalities are made available within an ecosystem of customers, third party developers, FinTech startups, or partners.The services provided are financial and may come from banks as well as from third parties.Data sharing, accessibility, shared values, and collaboration are the main concepts defining open banking paradigm.
Following open banking, another platform-based business approach that is named as "beyond banking" emerged.There are different service providers providing multiple services to customers in this approach.These services are provided in an integrated and harmonious manner.The range of the content of these services have a large variety (e.g.mobility, security, delivery, home security) and banks can be part of this procurement process by providing niche and tailored financial services that consistently integrate the scope of services.This is the vertical integration that is the strategic part of value creation in a more competitive banking business environment.For value creation and benefit optimization, a vertical integration of operational process with specialized partners having cost efficiency in each step of business is of strategic importance.(Deloitte, 2018).
Open banking and beyond banking concepts set-up the bank of the future model in a respective manner.In open banking, banking providers do perform business in banking platform with data sharing and accessibility resulting in collaboration.Banking Provider refers to a leading supplier of (certain) financial services through third party platforms.In this respect, banking providers are comprised of banks, other financial institutions, third party developers, FinTech companies etc.Hence, Banking Platform is a digital platform where supply and demand, in other words providers and customers meet, where the banks or third party financial products and services are offered to the bank's customers.With beyond banking concept, banking platform transforms into an exponential platform which is developing and owning a digital platform where all types of (connected) services are offered to customers in a coherent manner (Deloitte, 2018) with respect to aforementioned vertical integration.Due to this vertical integration, banking providers and service providers are together in the ecosystem.This paradigm shift is displayed in Figure 1 below.As seen from the figure, connected economy includes scope of products and services whilst connected customer contains control of client relations, distribution channels and ecosystems.Connected economy displays current banking products and services of today, open banking and beyond banking of tomorrow.Connected customer covers own platform and platform owned by others.In this respect, current banking products and services of today have today's bank as own platform and banking provider as platform owned by others.Open banking of tomorrow has banking platform as own platform and banking provider as platform owned by others.Finally, beyond banking of tomorrow has exponential platform as own platform and banking and services provider in a more comprehensive manner.
Increasing competition in banking and finance sector shapes the future of this new business model with increasing need for collaboration.For example, it is crucial for FinTechs not to stay behind digital champions and develop further in the direction of exponential platforms for this goal.As customer demand shifts towards more complex banking products, they need to broaden the extent of their services in traditional banking services to meet this dynamic demand.This necessitates collaboration with banks and other specialized FinTechs.Increasing and dynamic collaboration and interaction correspond to the aspects of the future of banking named as beyond banking.Open innovation, sharing economy and shared marketplace in a data-intensive manner define the future paradigm.
Dynamic character of future paradigms for finance sector has repercussions in the emergence of a following concept, Open X, which is a common platform, in a sense a shared marketplace and actors of this platform are in a data-intensive framework with extensive utilization of data.Another major characteristic in this platform is collaboration among actors for the sake of the quality and sustainability of their services (Capgemini, EFMA 2019).This new paradigm forces actors to change their business model culture and technology architecture by leaving outdated business patterns and starting a radical digital transformation.
The future of banking business, defined by a common platform or a shared marketplace, is a phenomenon that actors of the ecosystem should consider as beyond open banking to remain in the ecosystem.The existing actors of the ecosystem, banks have extensive resources, networks of huge volumes of customers.On the other hand, FinTechs, as more recent actors of the ecosystem, are more flexible in their business models and methods and have a more entrepreneurial consideration, a start-up spirit together with their human-centered design expertise and technological capabilities.Thus, partnerships and collaborations will result in a win-win situation in this respect when these peculiarities are considered.
In this paradigm defined by partnerships and collaborations of actors in the ecosystem, with the utilization of technology, tailor-made financial services and customer feedbacks define the crossroads of customer experiences of financial services.This new paradigm is defined by the shift of the focus from products to customer experience, from assets to data centered approach, from ownership to shared access and from buying or building to partnering.
Application Programming Interfaces (APIs), a software intermediary that allows two applications to talk to each other, are utilized in open banking and are crucially important means in the Open X environment.APIs, as drivers of innovation, provide flexibility to the actors to develop the quality of the customer experience and to provide prompt launching of products.As the industry moves towards an open architecture and as API recognition enhances, ecosystem players must utilize the use of standardized APIs in order to help reducing fraud, improving interoperability and increasing scalability.APIs are not only used by banks and Fintechs, but also by BigTechs like Google, Amazon etc. for integrating or monetizing services.APIs, information and information structure are important components of Sharing Economy that emphasizes the role of collaboration.
Open X environment is also defined with a shift of financial services having four pillars (Capgemini, EFMA 2019).The first pillar is the shift of focus to customer experience (vs.products).Transition from traditional banking to digital banking, digital banking to open banking and open banking to Open X is to be mentioned in this context.Products, ownership, build/buy and assets are respectively replaced by experiences, shared access, partner and data in Open X environment.Consent and trust with respect to data driven and data intensive business are main concepts in this manner.That is to say, trust of customers to banks and their data, which can be quitted by customers easily, define the consent economy and in this respect, banks must be able to integrate their services without any problems.The second pillar is evolving of data as a critical asset.With the evolution of "big data" as a major asset in data-driven economy, strategic utilization of data to benefit from new revenues, creating value and enhancing intuitive decision-making are main issues.Increasing volume of data and the need for data analysis let to utilization and adaptation of Artificial Intelligence (AI) in financial services for understanding customer needs better, prompt and precise analysis and decision-making and thus transforming the business culture towards that of start-ups in a dynamic manner.
Partnering of firms instead of unilaterally developing and purchasing capabilities is the third pillar.In this respect, to deliver value to end customers, Open X will force the pace of partnerships between the actors like banks, FinTechs and others for a more efficient ecosystem.It is important to have an encouraging and broadly skilled ecosystem to overcome challenges like data privacy, barriers due to regulatory framework, fraud, preclusion of the trust of customer and channel expertise.Shared access is the fourth pillar which is due to capabilities and asset ownership.Partnerships in the ecosystem will cause the transformation of ownership to a shared economy.Exploring the opportunities of shared economy following Uber and Airbnb has been a common situation in many industries.As a result, there emerges new product development and distribution opportunities due to in-house efforts or partnerships with other actors in the developing financial sector ecosystem.In this respect, the shift from competition to collaboration in the financial ecosystem stems from structural collaboration.Elements of effective collaboration are people, finance, business and technology.
Consequently, digitalization and its effects as a major paradigm shift in the ecosystem are stated above.With considering these changes and related literature, the qualitative study comprised of structured interviews is structured and conducted.The methodology of this qualitative study is stated in the following section.
Methodology
To understand the effect of digitalization and related policy recommendations on Turkish Banking Sector (TBS), a qualitative study (Patton, 2002) comprised of structured interviews are conducted.All interviewees are asked the same, pre-established, questions in order to minimize researcher bias and increase generalizability of the findings (Qu, 2011).The interviews are conducted on Zoom due to Covid-19 pandemic.Representing all the groups of banks in TBS, different banking groups like state-owned banks, private deposit banks, Islamic participation banks, medium-sized banks and foreign banks are considered in this study.Seven representative banks selected in this study in terms of bank types are based on the tradeoff between the quantity of cases and in-depth studying (Kalling, 1999).Also, when selecting the banks, attention was paid on having a variety instead of a large amount of banks as has been done in various previous studies (e.g.Gsell and Mette, 2017).Selected banks are listed as: Bank A -medium scale foreign deposit bank; Bank B -big scale private deposit bank; Bank C -medium scale participation bank; Bank D -state development bank; Bank E -big scale private deposit bank; Bank F -medium scale private deposit bank; Bank G-medium scale state-owned deposit bank.
One bank from each banking group, as a relevant sample size represents the TBS in a sound manner.Banks are selected in accordance with the classification of Banking Regulation and Supervision Agency (BRSA).Asset share of selected banks in the study comprise about 40% of Turkish Banking Sector as of 2019 year-end.This sample size, in terms of covering different types of banks in the sector, as classified by BRSA, and covering the 40% of assets of TBS is a reasonable and saturated sample for the sector.More interviews with other banks have started to be iterations of findings of this study, in this regard due to the saturation level of the sample, the sample size is kept as seven diversified banks (Patton, 2002).
Selection criteria of the interviewees were mainly relating to their position in leading and managing the digitalization strategy and process of their banks.Therefore, all participants are in the top management positions responsible from and/or closely related to strategy and digitalization in their banks.They are either Vice-Presidents or Department Heads responsible from digitalization, digital transformation, alternative distribution channels and/or IT systems so that they provide not only perspective of their banks but also an overview of the industry together with projections for future regarding the industry and their bank.
Analysis and Findings
The data collected through a structured interview is analyzed using the pattern-making approach presented by Yin (2014).Quotations derived from interviews and related analysis are stated below with respect to certain topics.
Digitalization and Sector Competition
Digital transformation has started in Turkish banking sector around 2015-2016 as stated by Bank A.
BANK A "In 2015, we have started mobile banking in Turkey.For digitalization, there is no such a thing as one-size-fits-all."
As mentioned by Bank B and Bank C, Turkish banking has become one of the leaders in the world; better than US and Europe banking in terms of service quality and variety, especially in the retail banking operations (Bank F).In fact, the installment option to credit cards is one of the inventions.BANK B "Turkey is in front of Europe and US in terms of service quality in banking.Our customers are spoiled.This is a demand-driven sector."BANK C "Turkish banking sector is much better than Europe and US in terms of product variety.For example, installment to credit card is our invention" BANK F "Retail banking is faster than corporate banking in digitalization."
In fact, as stated by Bank E, Turkey has 56 million digital banking users of which 44 million of them are using mobile banking.BANK E "There is digitalization index 2016 of Accenture and accordingly, Turkey in general is 61%, for financial companies 81%.Turkish retail banking digitalization has a leading role in the world.By January-March, according to banking association, there are over 56 million digital banking of which 44 million are using mobile banking.It is an important sales channel".
"First digitalization was a channel change, now it is the main channel" As a customer demand-driven sector, stated by Bank F, after digitalization, the competition has been based on service instead of price.The channels of providing services have been changed to digital platforms, mainly internet and mobile phones and due to the expectations and necessities of the consumers, the priority is given to seamless and personalized services (Bank B).As Bank D states, customers can easily change service providers according to their expectations.BANK F "There is customer driven competition" BANK B "New developments in technology brought radical changes.Specifically, as the internet and mobile phone usage has become an important part of our daily lives, individuals' expectations and necessities with their interactions with financial institutes have changed.""Now services provided out of the banks should be seamless" "There is a need to design personalized solutions and proposals.As the life expectancy has increased, there are new and niche segments that need extraordinary solutions" BANK F "Before digitalization, competition was based on price, now it is based on service.People want to get good service, fast accessibility, and trustful environment; we were focusing on product before; now we focus on customer" BANK D "Digitalization provided customer base enlargement as customers are quick to shift towards institutions with faster operations."
One main effect of digitalization of the sector has been providing high quality, fast, personalized, accessible services, the other is the reduction in the number of branches.The number of branches has decreased from 12.000 to 10.000 in the last few years.BANK B "…the effect of digital transformation banks has started to close their branches between 2017-2019" BANK F "Digitalization fastens and ease processes: customers' operations diversification and makes them paperless.In the long run, I think banking will be without branches.I cannot think of our children going to branches to pay electricity, gas bills, transfer money, buy currency etc. Branches may only be used for consultancy" "We have a digital financial portal that uses no branch operation, which has been very beneficial during pandemic" "For the last few years, the number of branches has decreased from 12.000 to 10.800" BANK G "In banking, digitalization brought branchless banking.We try to provide trustful, fast and user-friendly customer experience through internet and mobile banking"
With the decrease in the number of branches, more operations have to be handled through the digital platforms.That has brought the need of fast, trustful, innovative solutions to customer expectations, which is front desk operations, and also a new organizational system, back desk operations.To achieve this digital transformation, banks have started to use AI.
BANK G "Digitalization is transformation of knowledge and data to digital and it affected not only the product but also the whole system" BANK B "Now, AI is the trend" "Artificial intelligence, non-intermediary systems etc. affect doing business in the financial world" One additional effect of AI also has been on digital marketing as mentioned by Bank D. Therefore, besides operational processes and service quality, AI is increasing the quality of competition by digital marketing.BANK D "Retail banks started using AI.We are starting to use AI in pop-ups and digital marketing in our bank."New technology usage in the financial system has brought a new challenge to the competition.Banks have started to compete to provide new service channels and adapt/restructure their organization to the new digital world.That has created a necessity to cooperate with other technology and data driven companies such as Fintechs and technology firms.
BANK A "Digitalization is there, in some cases as leapfrog, in some slower.Maturity differs from one country to another, for example, Fintech is growing much high-er in China than any other country due to its market, population, and social status."BANK B "In Europe there is Payment Services Directive, Open Bank Standards, Opening APIs for Fintechs that create competition risk as threats to payment services, asset management, and financial consultancy services of banks" "In US there is GAFAM (Google, Amazon, Facebook, Apple and Microsoft) and in Asia there is BATPJ (Baidu, Alibaba, Tencent, Xiaomi, PJ Pingan and JD) as the giant technology firm competing aggressively against banks due to their collected data size, customer network and their expertise in AI" Turkey, as one of the leaders of the global banking sector in terms of product variety and quality, has been behind many countries in cooperating with other financial institutions.In the first decade of 2000s, due to investments for the adaptation of recent banking technologies, TBS was mentioned among the leaders in global banking sector as stated in the interviews.However, due to lacks in collaboration with Fintechs and other actors, TBS failed to create an innovation system and consequently, Turkey has been behind many countries as mentioned in the interviews.BANK F "Yet, we do not have enough cooperation with Fintechs.We are followers in that respect.If we put AI maturity level on a scale of 1-5 (1 lowest, 5 highest), our sector is 2"
Policy Recommendations
There have been some improvements in regulations to ease the adaptation process to digital transformations and Covid-19 period.For example, as Bank B states, some regulations promote financial technology, crisis management and Development Plan covering the issues of e-government and ID verification system to ease the adaptation of customers and banks to new technologies.Digital transformation of regulations in accordance is very important for ensuring the diffusion and adaptation of new technologies.BANK B "Regulations are promoting financial technology usage and increase competition in this area"."In Turkey, in the Development Plan, there are actions for diversifying financial institutions, developing e-commerce, retail chain, e-government open data and ID verification systems".
"The first reaction to 2001 crises makes the system stay on its feet".BANK C "Opening Digital Transformation Office and e-government portal by the government is good in terms of awareness".
As Bank F states, banking sector is in front of many countries in product variety and can be better if new regulations are adapted.For example, easing bank account opening by developed ID confirmation systems and harmonization of legal framework with respect to digital transformation.BANK F "Turkish banking sector is good in terms of technology, innovation, product diversification compared to Europe and US.However, it can become a leader if regulatory side is also adapted".
According to Bank B and E, Turkey needs government support for open banking.Convergence of legal framework with flexibilities for data sharing in TBS is a major issue.Legal framework restricts data sharing.However, harmonization of legal framework to digital transformation with flexibilities in data sharing, developed ID verification systems and substituting the need for physical signature are stated as main support from government in terms of adapting legal framework in this manner.BANK B "China, UK, US… all have open banking structure.Turkey could not step forward and get behind.Turkey is not like China.China has a large scale, product has a big chance of being successful.For us, we need government supported fragmentation and specialization" BANK E "The future is open banking and our country is in its initial stage.We need to share data with other institutions and this stage needs new regulations.""Regulations slow down the innovation process of banks" (Jakšič and Marinč, 2015; Vasiljeva and Lukanova, 2016).Bank B states that capital restrictions and controls and restrictions related to data sharing limit the improvements in innovation.BANK B "In Turkey, there are limitations due to regulations.From now on even bills will not be sent through email.Capital restrictions and controls prevent innovation improvements"."In the foundation of AI, there is data.In Turkey, according to the legislations, data should stay inside the country.For that reason, we could not utilize related cloud technologies and architects."Bank B and E mentions the importance of the role for unionized and secure structure of labor market for banks.BANK B "For the workforce, there has to be a sound union structure, employee focused culture and instead of firing there can be a retirement option".BANK E "Our service necessitates legislative responsibilities in terms of work security and with covid-19 life security."
As Bank E, C, and A state for new technology (blockchain and digital money) adaptation, especially for corporate banking, as Bank F mentions, which is not as fast as retail banking in digitalization, new regulations that ease the operations to use new technologies and trustful environment have to be made.BANK E "For blockchain and digital money, it is early to say something because traditionally government prints money.Of course, in economy these will be placed somehow, active reactive management, regulations, limitations will determine our activities" BANK C "For blockchain usage, there are question marks about having a guarantee by the government.For example, if I use blockchain for land registry system or smart contracts, will the government accept this, or will Central Bank accept money transfers by blockchain?" BANK A "Only the one on the top that has the control can temple of blockchain.Trust is a big issue.This is nationwide governmental strategic decision" "Digital money is also a national strategy.Central banks play key role" BANK F "Corporate banking is not as fast as retail banking in digitalization.To catch up, government should have new legislations."
In fact, as Bank F explains, some operations do still need physical signature.E-signature usage should be encouraged by building safe and standardized environment with regulations.Also, this paper based, time consuming and sometimes untransparent processes can be costly for advisory/supervisory authorities during the investigation period.In addition, Bank C mentions the importance of flexible regulations in some instances such as having an easier process for long distance account openings and/or opening a branch.BANK F "For example, onboarding has been our agenda, becoming customer process.We still need wet signature.This (e-signature) has passed as a regulation in the parliament but still should be supported by BDDK and MASAK to be safe" "Organizational processes have been digitalized even the supervisory controlling activities.There is no document or wet signature anymore, supervision process has been shortened" BANK C "We still cannot open a bank account for long distance.We have problems with AML (Anti-Money Laundering) and related KYC (Know Your Customer).We need more flexible regulations.Otherwise, technology companies for example mobile operators will be adapted very fast and start to give credits, open accounts etc." "BigTech, Techfin are threat for us.We have some regulatory limitations in this competition.For example, we need the permission of BRSA to open a branch but BigTechs do not need this kind of permission."Also, Bank D mentions the need of harmony in legislative framework for the sake of digital transformation.As mentioned above, Civil Law, Law of Obligations, Commercial Law and Banking Law should be amended to include digital signature in harmony with the digital transformation of working life, business and personal lives.In this respect, as opening bank account transforms to a digital operation, a major obstacle in digitalization of banking would be overcome.
Next section discusses these findings and analysis with policy recommendations and conclusion.
Discussion, Policy Recommendation and Conclusion
As the interviews with the selected banks show in this qualitative study, digital transformation has gained pace in Turkish Banking Sector by 2015 onwards.But with underlying grounds, the real transformation started by the second decade of the millennium.In parallel with the rapid diffusion of smart phones with 3G technology by 2001 onwards, first digital applications emerged.By these years, Turkish banks already began to adapt internet banking with late 1990s and early 2000s.The increasing volume of internet banking (Tekeli, 2017) was accompanied with WAP banking services provided by Turkish banks with an increasing wide range of services (Türkoğlu, 2002).
Rapid adaptation and diffusion of internet services and development of WAP banking technologies provided a prompt adaptation and learning process for cus-tomers.As mentioned in interviews, the paradigm of competition shifted from price competition to providing prompt and qualified services in Turkish Banking Sector.Besides, this paradigm shift, to maintain and develop their brand value, banks were facing pressure to be pioneers or not being laggards in adaptation and provision of new technologies (Türkoğlu, 2002).In this respect, as a repercussion of domino effect, the increasing adaptation of internet services, e-trade and digital services paved the ground for development of basic mobile applications, WAP banking and respectively, the competition in Turkish Banking Sector forced banks to rapidly adapt and provide these services to customers.
Customer demand as a driving force was one of the reasons of this adaptation of digital technologies.Another reason for this dynamic competition structure of Turkish Banking Sector was the ability of Turkish banks to invest in digital technologies to be pioneers in the sector in the first decade of 2000s.Due to stringent financial policy and supervision mechanism, Turkish Banks had strong capital adequacy ratios during the financial turmoil in that decade which paved the ground for investment appetite for new technologies.When product variety, customer satisfaction and sector is considered, Turkish banks are strong in adapting and developing digital products and technologies in a demand-driven manner.Hence, Turkish banking gained global significance in terms of service quality, product development and rapid adaptation of demand-driven digital technologies.The role of Turkish banks as early adapters or leaders is also emphasized in interviews.
However, until recent years, Turkish banks were mostly utilizing in-house resources for development of products and utilization of digital technologies as pointed in interviews.From 2015 onwards, we begin to see emergence of Fintechs and an eco-system with actors other than banks.Insufficiency of collaboration between banks, Fintechs and other technology companies is the recent problem of Turkish Banking sector for losing the global leading role and becoming a follower in this process.We need to see a more dynamic collaboration between banks, Fintechs and other technology developers in an eco-system for Turkish banking sector.That is to say, besides being strong in adapting digital technologies and changes, it is important to have a sound eco-system, an effective system of innovation with interactions and collaborations among actors to have a pioneer and leading role globally in digital competition as digitalization is not only an operational innovation but instead a new paradigm as pointed out in interviews.
To set up such a system of innovation, banks, government authorities, The Bank's Association of Turkey and/or other actors should have leaded banks and Fintechs to enhance collaboration networks.Turkish banks already have a history of collabora-tion with each other as in the examples of sharing POSs and ATMs for operational cost minimization.But on the contrary, Turkish banks lack in collaboration with Fintechs and other companies to be able to compete with technology companies.In terms of inter industry vs. intra-industry collaboration, the deficiency in inter-industry collaboration is a repercussion of conservativism and lacks in understanding the philosophy of digitalization, its effect in business models, new challenges that digitalization brings and the importance of digital tools in new business model of banking.Hence, it is possible to state that, a serious and long-term consideration of digitalization as a radical innovation in banking and all services sector will bring more focus and investment on development of digital technologies, products and rapid adaptation of them in collaboration with other actors of innovation system.This will most likely result in customer base enlargement with utilization of these technologies and creation of new digital business models and services.
Policy Recommendations
Policy recommendations have a large variety of topics to be covered.However, it is initially important to consider and express planned policies related with the content of this study that are stated in 11th Development Plan that was issued by Strategy and Budget Department of Presidency of Turkey in 2019.Digital transformation is a strategic factor as stated in the Plan.Therefore, accelerating digital transformation, development of interfaces, standards, measurement methodology for digital transformation is emphasized in this context.
The formation of a safe financial technology (Fintech) ecosystem together with a road map for its development, legislative alignment with the EU Payment Services Directive-2 for strengthening open banking legal infrastructure, establishing Association of Payment Services and Electronic Money Institutions and Istanbul Finance and Technology Base, implementing blockchain-based digital central bank money are following related goals denoted in the Plan.Hence, considering the policy goals of the Plan, innovation systems approach is used for designing policy recommendations to overcome policy problems and related weak points stated in this study.Therefore, development of collaboration networks, transformation of legal system, developing entrepreneurship in TBS by supporting Fintechs, revising regulatory and supervisory framework from innovation perspective, competence building and harmonization of work-life in this respect are major policy recommendations that will be detailed with policy aims, policy tools and policy targets respectively.
Policy recommendations are stated in Table 1 in the following pages and then stated in related topics, respectively.
Table 1. Policy Implications for Digitalization in Turkish Banking Sector
Policy Problem: Shortcomings and problems stemming from legal system that slow down the sectoral progress in digitalization -Legal System should be transformed in harmony with digitalization.
-Having a legal system in compliance with digitalization process.
-Revising and amending Civil Law, Law of Obligations, Commercial Law and Banking Law in accordance with digital transformation.
-Adaptation of digital signature and smart ID verification systems for customers in opening bank accounts.
-Revising legal framework for data sharing.
-Revising legal framework for data sharing.
Policy Problem:
The need for developing entrepreneurship in TBS in accordance with 11th Development Plan.
-Developing Enterpreneurship in TBS by supporting Fintechs.
-Utilizing the benefits of developed entrepreneurship by means of Fintechs.
-Having a developed entrepreneurial framework with knowledge spillovers and interactions in accordance with systems of innovation approach.
-Setting-up a framework for interactions of Fintechs with knowledge spillovers.
-Promoting new start-up Fintechs.
-Designing tax incentives and new funding opportunities for start-up Fintechs in collaboration with banks.
-Providing the legal basis of global competitive advantage for TBS in digitalization.
-Revising competition law in accordance with digitalization and new business models stemming from this process.
-Strategy and road map for a sectoral innovation system for TBS should be discussed and drafted by these joint working groups and committees.
-Collaboration networks in TBS should be developed.
-Developing a Technological System of Innovation in TBS.
-Promoting perception of Fintechs and banks as collaborators by joint activities and projects.
Having a sectoral innovation system with strong interactions and collaborations among stakeholders.Becoming digital leader and reaching the optimized digital maturity level in digital transformation maturity model of this study.
-BRSA is to have an innovation perspective for TBS and prepare innovation strategy documents with joint committees from sector.
-Penetration of universities and research institutes to the eco-system should be promoted by joint activities and projects.
-Joint working groups and committees comprised of all stakeholders stated above in the eco-system should be established.
Policy Problem: Insufficient inter-industry interactions and collaborations
Policy Recommentations
Policy Aims Policy Tools Policy Targets -Developing Enterpreneurship in TBS by supporting Fintechs.
-Setting-up a framework for interactions of Fintechs with knowledge spillovers.
Utilizing the benefits of developed entrepreneurship by means of Fintechs.
-Having a developed entrepreneurial framework with knowledge spillovers and interactions in accordance with systems of innovation approach.
-Promoting new start-up Fintechs.
-Revising and amending Civil Law, Law of Obligations, Commercial Law and Banking Law accordance with digital transformation.
-Adaptation of digital signature and smart ID verification systems for customers in opening bank accounts.
-Revising legal framework for data sharing.
-Designing tax incentives and new funding opportunities for start-up Fintechs in collaboration with banks.
-Revising legal framework for data sharing.
Organizing joint activities, seting-up study groups and committees with participation of sector actors for ranking and rating innovative capacities of actors in TBS, developing strategies for adaptation of future technologies like AI, blockchain and digital money.
Developing standards for APIs and implementation of other technological developments in TBS.
Collaborating with other banking regulation and supervision authorities in an international level for adaptation of various policies in other countries from an innovation perspective.
Policy Problem: Shortcomings and problems stemming from legal system that slow down the sectoral progress in digitalization -Legal System should be transformed in harmony with digitalization.
-Having a legal system in compliance with digitalization process.
Providing the legal basis of global competitive advantage for TBS in digitalization.
Having a dynamic innovation policy development framework with active participation of sector actors.
-Revising Regulatory and Supervisory Framework from Innovation Perspective.
-Having a proactive regulatory and supervisory framework from innovation perspective in TBS.
-Drafting sectoral innovation strategy and developing innovation rankings and ratings for banks.
Having a sectoral innovation system with strong interactions and collaborations among stakeholders.
-Developing sectoral digital maturity level models and rating banks in accordance.
Policy Problem:
The need for a leading role in developing standards, sectoral strategy and road map for digital transformation and setting up a systems of innovation with a revised regulatory and supervisory framework from innovation perspective.
Policy Recommentations
Policy Aims Policy Tools Policy Targets
Development of Collaboration Networks
Insufficient inter-industry interactions and collaborations are policy problem that necessitates development of collaboration networks for the policy aim of developing a system of innovation in TBS.Therefore, enhancing interactions and collaborations between banks, Fintechs, technology companies, regulatory and supervisory authority, universities and research institutes as stakeholders are main components of this policy aim.
In order to enhance these interactions and collaborations, policy tools are as such:
• Promoting perception of Fintechs and banks as collaborators by joint activities and projects.
• Regulatory and supervisory authority, BRSA, should have an innovation perspective for TBS and prepare innovation strategy documents with joint committees from sector.
• Penetration of universities and research institutes to the eco-system be promoted by joint activities and projects.
• Joint working groups and committees comprised of all stakeholders stated above in the eco-system should be established.
• Strategy and road map for a sectoral innovation system for TBS should be discussed and drafted by these joint working groups and committees.
Policy target for TBS in this context is having a sectoral innovation system with strong interactions and collaborations among stakeholders.
Transformation of Legal System
Shortcomings and problems stemming from legal system in the operational process that slow down the sectoral progress in digitalization are policy problems that necessitate transformation of legal system in accordance with digitalization.Policy aim in this title is having a legal system that is door opening for digitalization and innovations in TBS.
Policy tools for such a legal system are stated below:
• Revising and amending Civil Law, Law of Obligations, Commercial Law and Banking Law in accordance with digital transformation.
• Adaptation of digital signature and smart ID verification systems for customers in opening bank accounts.
• Revising competition law in accordance with digitalization and new business models stemming from this process.
• Revising legal framework for data sharing.
Policy target in this context is to provide legal basis of global competitive advantage for TBS in digitalization.Therefore, increasing pace of adaptations and developments in digitalization may attribute a leading role to TBS in digital globalization.
Transformation of Legal System
Shortcomings and problems stemming from legal system in the operational process that slow down the sectoral progress in digitalization are policy problems that necessitate transformation of legal system in accordance with digitalization.Policy aim in this title is having a legal system that is door opening for digitalization and innovations in TBS.
Policy tools for such a legal system are stated below:
• Revising and amending Civil Law, Law of Obligations, Commercial Law and Banking Law in accordance with digital transformation.
• Adaptation of digital signature and smart ID verification systems for customers in opening bank accounts.
• Revising competition law in accordance with digitalization and new business models stemming from this process.
• Revising legal framework for data sharing.
Policy target in this context is to provide the legal basis of global competitive advantage for TBS in digitalization.Therefore, increasing pace of adaptations and developments in digitalization may attribute a leading role to TBS in digital globalization.
Developing Entrepreneurship in TBS by supporting Fintechs
Entrepreneurship is an important phenomenon to be promoted as stated 11th Development Plan.Hence, there is a need for supporting and developing entrepreneurship in financial sector in accordance with development goals.As a result, policy aim in this respect is having a developed entrepreneurial framework with knowledge spillovers and interactions in accordance with systems of innovation approach.Policy tools for developing entrepreneurship in TBS by supporting Fintechs are stated below:
• Setting-up a framework for interactions of Fintechs with knowledge spillovers.
• Promoting new start-up Fintechs.
• Designing tax incentives and new funding opportunities for start-up Fintechs in collaboration with banks.
As a result, policy target in this context is utilizing the benefits of developed entrepreneurship by means of Fintechs.They are very dynamic and agile actors with high skills of adaptation and innovative capacities in the ecosystem.They are able to trigger banks for enhanced collaboration and develop a system of innovation with enhanced innovative capacity.
Revising Regulatory and Supervisory Framework from Innovation Perspective
The need for a leading role in developing standards, sectoral strategy and road map for digital transformation and setting up a system of innovation necessitate revising regulatory and supervisory framework from innovation perspective.Policy aim in this perspective is having a proactive regulatory and supervisory framework from innovation perspective in TBS.
In this respect, policy tools for revising regulatory and supervisory framework from innovation perspective are stated below:
• Drafting sectoral innovation strategy and developing innovation rankings and ratings for banks.
• Developing sectoral digital maturity level models and rating banks in accordance.
• Organize joint activities, set-up study groups and committees with participation of sector actors for ranking and rating innovative capacities of actors in TBS, developing strategies for adaptation of future technologies like AI, blockchain and digital money.
• Develop standards for APIs and implementation of other technological developments in TBS.
• Collaborating with other banking regulation and supervision authorities in an international level for adaptation of various policies in other countries from an innovation perspective.
Hence, policy targets in this context are having sectoral indicators, as rating and ranking of innovation for sector actors in solo basis and for sector in a consolidated basis, and a dynamic innovation policy development framework with active participation of sector actors.
Competence Building and Harmonization of Work-Life
With respect adaptation of technologies like AI, the need for human factor in banking and mainly in-service sector decreases.Moreover, new technologies are prone to create employment problems in service sector and more specifically in financial sector.Hence, competence building and harmonization of work-life in TBS in accordance with digitalization and technological developments are policy aims in this context.
Policy tools for competence building and harmonization of work-life in TBS in accordance with digitalization and technological developments are stated below:
• Joint committees and working groups comprised of sector representatives, unions and state authorities should work together for developing strategies for competence building in TBS and coping with negative employment effects new technologies.
• Unions should be more active and in collaboration with TBS, together with universities in developing competence building academic programs.
• Collaboration of TBS with universities for developing curriculums and training their staff, forming bank academies like data academy etc.
• Framework of Labor Law need to be revised in accordance with new business models and work relations stemming from digitalization and other technological developments.
• Retirement options need to be promoted in TBS, instead of firing from work due to decreasing need for personnel because of digitalization.
• Need for enhanced negotiations, communication, interactions and networks of unions and TBS.
• As experienced during Covid-19, developing a culture of distant working, working from home in TBS.
Policy target in this context is coping with employment effects of new technologies with more competent human capacity, utilizing new employment opportunities for developing requirements for new skills.Thus, development of skills and competency of human capacity is important as a social policy, in the era of rapidly changing requirement for skills and substitution of human factor by technology (like AI mainly in finance sector etc.).
These policy recommendations can be extended with more topics.But major headlines of policy development in this regard are mainly as stated above.
Conclusion
These findings and discussions reveal the fact that there is a need for a holistic approach to set up the framework for development of collaboration networks, transformation of legal system, developing entrepreneurship in TBS by supporting Fintechs, revising Regulatory and Supervisory framework from innovation perspective and competence building and harmonization of work-life.In fact, supporting Jakšič et al. (2015) and Vasiljeva et al. ( 2016) that mention the probable restrictive effect of regulatory framework on banks' innovative processes, the bank directors interviewed in this study also point out the importance of flexibility and adaptation of regulations in the innovation ecosystem.TBS needs a leading actor to set up an innovation framework.Therefore, regulatory and supervisory authorities may have such a role in setting a sectoral innovation system both in Turkey and globally.
In addition, looking at the business model approach, as Ditshego (2018) states and repeatedly mentioned by the current study's interviewees, changes in value creation stemming from digitalization necessitate fast, accessible, and efficient operations that satisfy customer expectations.In this respect, supporting Deloitte (2018), our results show that vertical integration of operational process with specialized partners having cost efficiency in each step of business gains strategic importance.
Hence, this strategic partnership consideration leads to a platform banking approach (Open X) for sustainable banking services.The new paradigm has been discussed by Capgemini EFMA (2019) as a change in business culture and technology architecture with radical digital transformation.This new development is also mentioned by bank directors interviewed through the needs of collaborating with Fintechs and perceiving them as complementary partners while defining Big Techs and technology companies as potential competitors.To gain a competitive advantage in the sector, banks need to develop and gain experience on tools such as APIs and AI to enhance innovative capacity and customer experience quality.As mentioned by the interviewees, regulatory authorities are expected to provide safe and transparent environment for these new technological transformations.
For further studies, the effect of Covid-19 experience on policy development, competence building, harmonization of work-life and working relations in the context of digitalization are other important issues to be considered.The impacts of digitalization and Covid-19 on the business models of banking sector has been explored recently (Yıldırım, 2020) and will be searched by many other qualitative and quantitative studies in the aftermath.
Figure 1 :
1
Figure 1: Bank of the future model
Table 2 . Policy Implications for Digitalization in Turkish Banking Sector (continued) Policy Problem:
2
The need for developing entrepreneurship in TBS in accordance with 11th Development Plan.
A. C. Yıldırım, "Turkish Banks and Digitalization: Policy Recommendations from a Qualitative Study ", Journal of BRSA Banking and Financial Markets, 14, (2), 2020, 145-174
Journal of BRSA Banking and Financial Markets, 14, (2), 2020, 145-174
Redefine Banking with Artificial Intelligence. Accenture , 2017
The Diffusion of Financial Innovations: An Examination of the Adoption of Small Business Credit Scoring by Large Banking Organizations. J Akhavein, W S Frame, L J White, Journal of Business. 7822005
World Retail Banking Report. Efma Capgemini, 2019
J Cherowbrier, Number of active mobile banking customers in Turkey. 2020. 2014-2018
Finansal Yenilik Yazınındaki Son Gelismeler, STPS Working Papers 1604, STPS -Science and Technology Policy Studies Center. H Comert, G Epstein, 2016. Jan 2016Middle East Technical University
Why So Many High-Profile Digital Transformations Fail. T H Davenport, G Westerman, Harvard Business Review. 2018
Deloitte, EMEA Digital Banking Maturity Report. 2018www2.deloitte. com/DigitalBankingMaturity
Assessing the Influence of Digital Transformation on Digital Maturity within a Large Corporate Bank. K J Ditshego, 2018North-West Universitydissertation paper
PSD-2) Directive (EU). Payment Services. European Union2015. 2015/2366
The Impact of Digitalization on the Business Model of German Retail Bank, 11. S Gsell, J Mette, 2017
The Future of Banking: The Role of Information Technology. M Jakšič, M Marinč, The Journal for Money and Banking. 64112015
Gaining competitive advantage through information technology: A resourcebased approach to the creation and employment of strategic IT resources. T Kalling, 1999Department of Business Administration, Lund UniversityPhd Thesis
Guidelines for Collecting and Interpreting Innovation Data-Third Addition. Organisation for Economic Co-Operation and Development. Oslo Manual, 2005OECD
Türk Bankacılık Sektöründe Etkinlik ve Verimlilik Aanalizinin Veri Zarflama Yöntemi ile İncelenmesi. N Özel, İ Şahin, R Göral, 2017
Sosyal Ekonomik Araştırmalar Dergisi. Dönemi Uygulaması, 17
M Q Patton, Qualitative Research & Evaluation Methods. London, New DelhiSage Publications20023rd ed.
S Q Qu, J Dumay, The Qualitative Research Interview. Qualitative Research in Accounting and Management. 20118
İnternet Bankacılığı ve Mobil Bankacılığın Tarihsel Gelişimi. Glokal Web. E Tekeli, 2017
Population Statistics, Main Statistics. 2020Turkish Institute of Statistics (TURKSTAT)
Bankaların Verdiği WAP Hizmetlerinin Gelişimi. R Türkoğlu, 2002
On Birinci Kalkınma Planı. 2019. 2019-2023
Commercial Banks and Fintech Companies in the Digital Transformation: Challenges for the Future. Samsung Tüsiad, Deloitte Türkiye, Türkiye, T Gfk Türkiye ; Vasiljeva, K Lukanova, Journal of Business Management. 112016. 2016Türkiye'deki Dijital Değişime CEO Bakışı
R K Yin, Case Study Research Design and Methods. Oaks, CASage2014Thousand
Digitalization of Turkish Banking Sector: Preliminary Results of a Qualitative Study. A C Yıldırım, 2019IstanbulInternational Engineering and Technology Management Summit
The Impacts of Digitalization and Covid-19 on the Business Model of Banking: A Qualitative Study on Turkish Banks. A C Yıldırım, 2020Middle East Technical UniversityMaster's Thesis
Türk Bankacılık Sektörünün Tarihsel Gelişim Süreci. Finans-Politik ve Ekonomik Yorumlar. O Yıldırım, S Ülgen, 200643
| [
0.014930707402527332,
-0.02761148288846016,
-0.12977971136569977,
-0.0740765929222107,
-0.08698061108589172,
-0.030599037185311317,
0.08792954683303833,
0.1361124962568283,
0.017296072095632553,
0.05010140687227249,
-0.03556327521800995,
0.09535053372383118,
0.03792886435985565,
-0.0723754... |
Impact Factor
Peter the Great St
Peter the Great St. Petersburg Polytechnic University Senior Lecturer
Peter the Great St. Petersburg Polytechnic University
Petersburg Polytechnic University
Impact Factor
Introduction
Every day new products are born and requirements for IT products will certainly grow due to the growth of the market. So, computer programmers and system administrators have to monitor the system in real-time by different monitoring systems like Prometheus with Grafana and common logging files, that's can be used in ELK stack (ElasticSearch + Logstash + Kibana). Thus, it's very important to think about the structure of logging: How we should write it? In which places and how often we should logging? How to write logs which will be understood by other employees, not only programmers, who wrote this piece of code? Do we need a common logging policy to our company to maintain the quality of the system at a high level and that the logs remain homogeneous in the entire application?
Modern realities force companies to develop their logging policies, that extends to the entire product and to each developer. So, this article offers a logging policy (that was introduced in one FinTech company) for IT company and modifications for logging library ( Slf4j with Log4j ) to integrate it into the mentioned earlier logging policy. [1,2] Describing API of the improved logging system
We assume the library has a LogTag class which is responsible for a separate tag (EXCEPTION, START, FINISH ...) and related information -a serial number and a description. The LogTags class wraps the LogTag and stores all the listed tags (LogTag) for a particular entry. LogTags operates with methods to add new tags, remove tags from the set, intersect tags and provide tags toString() representation as an ordered and formatted string.
The LogTiming class proposed to be responsible for storing the operation duration time in milliseconds inside a variable type of Long. This class not only stores the duration of the operation but also provides a method for forming a textual representation of the current object.
The LogTuple class is a common tuple which stores a single key and its associated value. The LogTuples class is a wrapper for LogTuple, that is, it stores a set of tuples. The methods of the LogTuples class allow you to operate on tuplesadd a new tuple, form a set of tuples from the Mapped Diagnostic Contextprovide a textual representation of a set of tuples for a logging entry.
[3]
The LogMessage class is a representation of the complete log entry, which contains LogTiming, LogTags, LogTuples, the cause exception and, accordingly, the text message itself with the necessary parameters. It is this class that forms the complete line for passing it to Log4j for further processing.
The Log class is the util class for quickly creating a LogMessage object with a single tag value, timing, tuple, exception, or message.
In the new logging policy, all logging operations are performed through the logger package ru.payment.system.logging.base. It applies the delegation pattern to the standard log4j logger, but takes as its parameters a new object of the LogMessage class, described earlier.
[4]
Describing the logging policy key feature
The first feature requires logging all exit points from the method with messages, that describes a business task that was completed before method completion (see Figure 1).
Figure 1 -first feature of logging policy
The second feature requires logging all GET HTTP requests with logging all URL parameters in the first line of the controller method, that receives a request. It information needs to state a fact of receiving an incoming request with correct parameters (see Figure 2). The third feature requires logging full POST HTTP request encoded body if that request is responsible for creating a new entity in the system. So in log files developers and system administrators will able to monitor of creating new entities with predefined fields (properties) (see Figure 3) [5].
Figure 3 -third feature of logging policy
The four feature requires logging full POST HTTP request encoded body with existing entity fields (what was and what will be), if that request is responsible for updating exists entity in the application (see Figure 4).
Figure 4 -four feature of logging policy
The fifth feature requires logging all outgoing requests with tag -TX, so it will speed up the search by tag if computer programmers or system administrator want to see outgoing requests in detail.
In demo payment service there is no outgoing requests.
The six feature requires logging all incoming requests with tag -Rx, with the same meaning as in fifth feature description (see Figure 5). The seventh feature requires logging all exception cases with tag -EXCEPTION to monitor extraordinary cases by special useful tag. This tag very important for system administrators while the deploying microservice on production to decide if need rollback for this release (see Figure 6).
Figure 6 -seventh feature of logging policy
Advantages of the new approach
With the introduction of the logger and the new policy into operation, the following advantages can be distinguished compared to the usual logger Slf4j and informal logging: 1) there is a convenient opportunity to quickly search for tags using Linux utilities grep and less; [6] 2) there is an understandable plan for logging and clear requirements for log entries, so the trace becomes homogeneous and structured; 3) the obligatory condition of additional parsing of log entries in CSV format (using the strategy developed when modifying the logger) allows you to build analytical repositories that can easily parse and use incoming format (CSV); [7] 4) system behavior has become easier and more convenient to monitor -each team member knows which log file to look at and what information can be obtained from it; 5) due to a clear plan and requirements for logs, unnecessary (unnecessary, irrelevant) logs became less. Thus, disk space is spent more efficiently; 6) due to the clear structure of the logs and the CSV format, the possibility of abandoning monitoring systems, such as Prometheus and Grafana, has appeared. Logs can be parsed in real time and display graphics on the screen; [8,9] 7) It has become easier for system administrators to maintain working componentsthe fact of an error is important for them, and not the stack trace (which usually has large sizes and does not fit in one terminal session), which carries an informative load only for developers;
Disadvantages of the new approach
When introducing a new logging policy and a modified logger, several weaknesses were also identified: 1) a new dependency must be added to the project with a modified logger; 2) the need to bring a new logging API for each developer in the team; 3) teams need a tougher and more attentive review code to keep the logging system in a homogeneous state; 4) The "old" Slf4j API is still available for developers and they can use it by mistake;
All these drawbacks lose their significance against the background of the advantages that we get for monitoring the whole application (microservice) within a large team of developers and system administrators whose work and time are expensive. When introducing and operating a new logging policy and a modified library, the quality of monitoring components inside the system was significantly improved, the work of system administrators (who do not know the business code and the tasks performed inside the components as thoroughly as the developers know) was greatly facilitated. Due to a large amount of work on implementation and maintenance, first, the new approach will be extended to new components that are not yet in production, as well as to the most key places of the legacy system (which perform key tasks in the payment system). Over time, an increasing number of components and modules will apply a new approach to logging, which has proven successful for industrial development.
Figure 2 -second feature of
2Figure 2 -second feature of logging policy
Figure 5 -
5six
Log4j -Log4j 2 Thread Context. Retrieved. Prometheus documentation. Retrieved. Grafana documentation. Retrieved. Retrieved(n.d.). SLF4J documentation. Retrieved June 02, 2019, from https://www.slf4j.org/docs.html 2. (n.d.). Log4J documentation. Retrieved June 03, 2019, from https://logging.apache.org/log4j/2.x/javadoc.ht ml 3. (n.d.). Log4j -Log4j 2 Thread Context. Retrieved June 03, 2019, from https://www.baeldung.com/mdc-in-log4j-2- logback 4. (n.d.). Delegation pattern. Retrieved June 03, 2019, from https://en.wikipedia.org/wiki/Delegation_patter n 5. (n.d.). In Introduction to HTTP Basics. Retrieved June 03, 2019, from https://www.ntu.edu.sg/home/ehchua/program ming/webprogramming/HTTP_Basics.html 6. (n.d.). Using less and grep with logs. Retrieved June 04, 2019, from https://www.ianlewis.org/en/using-less-and- grep-with-logs 7. (n.d.). Comma-separated values format. Retrieved June 04, 2019, from https://en.wikipedia.org/wiki/Comma- separated_values 8. (n.d.). Prometheus documentation. Retrieved June 05, 2019, from https://prometheus.io/docs/introduction/overvie w/ 9. (n.d.). Grafana documentation. Retrieved June 05, 2019, from https://grafana.com/docs/ 10. (n.d.). Microservice. Retrieved June 05, 2019, from https://en.wikipedia.org/wiki/Microservices
| [
-0.020881175994873047,
0.055537428706884384,
-0.07260417938232422,
-0.026151496917009354,
0.07578597962856293,
-0.12503379583358765,
0.10960040986537933,
0.09109918773174286,
-0.041526585817337036,
0.10497215390205383,
-0.028456829488277435,
0.09511277079582214,
0.05496648699045181,
0.0181... |
*，川﨑つま子 2) ，松浦正子 3) ，ウィリアムソン彰子 4) ，平岡 翠 5) ， 鈴江智恵 6) ，伊藤てる子 7) ，真下綾子 8) ，近藤恵子 9
日本看護科学会誌 J. Jpn
Acad
*，川﨑つま子 2) ，松浦正子 3) ，ウィリアムソン彰子 4) ，平岡 翠 5) ， 鈴江智恵 6) ，伊藤てる子 7) ，真下綾子 8) ，近藤恵子 9
J. Jpn. Acad. Nurs. Sci
40202010.5630/jans.40.4841) 長野県看護大学 Nagano College of Nursing 2) 東京医科歯科大学医学部附属病院 Tokyo Medical and Dental University Medical Hospital 3) 日本赤十字豊田看護大学 Japanese Red Cross Toyota College of Nursing 4) 神戸大学医学部附属病院 Kobe University Hospital 5) 岐阜保健大学 Gifu University of Health Science 6) 一宮研伸大学 Ichinomiya Kenshin College 7) 仙台青葉学院短期大学 Sendai Seiyo Gakuin College 8) 東海大学 Tokai University 9) 長野県看護大学 Nagano College of Nursing 484：nursing managercompetencyscale developmentreliabilityvalidity
Objective:To develop a key competency scale of nursing manager. Methods: A questionnaire survey was conducted on 4,410 nursing managers who work at facilities of University hospital and facilities of regional medical support hospitals. We set 50 items on key competencies of nursing manager, and performed item analysis and factor analysis. Te construct validity is checked the model to validity confrm and the coexistence validity is checked using NACAS; Nursing Administrator's Competency Assessment Scale. Te reliability confrmed internal consistency by Cronbach's alpha coefcient.Results: A total of 2,480 nursing manager were response (collection rate 56.2%) and 2,330 valid responses were analyzed. Five factors were extracted as a result of factor analysis, situation awareness, meta-cognitive, self-control, career support, decision making. Te ftness of the model consisting of 5 factors and 30 items was GFI = .907, AGFI = .899, CFI = .921, RMSEA = .047, and the construct validity was confrmed. Te correlation between the extracted fve factors and lowerlevel concepts of NACAS was r = .34 to .63, confrmed coexistence validity. Te alpha coefcient of each factor was .81 to .88, confrmed the internally defned consistency.Conclusions: Te reliability and validity of the key competency scale of nursing manager; KCSNM were verifed. 要 旨 目的：看護管理者のキーコンピテンシー尺度を開発する． 方法：特定機能病院と地域医療支援病院に勤務する看護管理者 4,410 名を対象に質問紙調査を実施し た．看護管理者のキーコンピテンシー 50 項目の項目分析と因子分析を行った．構成概念妥当性はモデル の適合度指標を用いて確認，併存妥当性は看護管理者のコンピテンシー評価尺度(NACAS)を用いて確 認した．信頼性は Cronbach の α 係数で内的整合性を確認した． 結果：看護管理者 2,480 名から回答が得られ(回収率 56.2%) ，有効回答 2,330 名を分析対象とした． 受付日：2019 年 12 月 17 日 受理日：2020 年 10 月 6 日
30 項目(状況認識，メタ認知，自己管理，キャリア支援，意思決定)が抽出さ れた．モデルの適合度は GFI = .907，AGFI = .899，CFI = .921，RMSEA = .047 であり構成概念妥当性が確 認された．5 因子と NACAS の下位概念との相関は r = .34～.63 であり併存妥当性が確認された．5 因子 の α 係数は .81～.25 コンピテンシー(武村，2014) ，6 領 域 20 コンピテンシー(虎の門病院看護部，2013) ，3 概念 15 能力(小澤・村田，2014) ，11 コンピテンシー (井上，2014) ，看護管理能力 12 因子 48 項目(八尾ら， 2012) ，看護管理実践能力 20 項目(松下，2001) ，基本 的管理能力 13 項目(
4．信頼性の検証30 項目全体の Cronbach の α 係数は α = .93 であっ た． 各因子の α 係数は， 第 1 因子 【状況認識】 が α = .88， 第 2 因子【メタ認知】が α = .81，第 3 因子【自己管 理】が α = .83，第 4 因子【キャリア支援】が α = .86，第 5 因子【意思決定】が α = .85 であり，内的整合性が 度指標は GFI，AGFI，CFI の値が 1 に近いほどあては まりが良いとされ，RMSEA は .50 以下であてはまりが 良いと判断される(豊田，2007) ．本研究のモデルの適 合度は GFI = .907，AGFI = .899，CFI = .921，RMSEA = .047 であり，妥当な適合度を示す結果であると判断 でき，構成概念妥当性を支持する結果と考える．併存 妥当性について，既存尺度 NACAS ( 本村・川口， 2013 ) を 用 いて検証した結果，本研究の 5 因子と 看護管理者のキーコンピテンシー尺度の開発 NACAS の下位概念 4 因子との相関は r = .34～.63 であ て，内的整合性を検証した結果，各因子の Cronbach の α 係 数 は .81 ～ .88 で あ っ た ． 内 的 整 合 性 は 一 般 に Cronbach の α 係数が α = .80 以上の値が望ましいとさ 本研究は【状況認識】 【メタ認知】 【自己管理】 【キャ リア支援】 【意思決定】の 5 因子 30 項目からなる「看 護管理者のキーコンピテンシー尺度」を開発した．こ の尺度のモデル適合度は GFI = .907，AGFI = .899，CFI = .921，RMSEA = .047 を示し構成概念妥当性が確認さAssessment Scale)を開発し，信頼性と妥当性を検証し
ている．しかしながら，この尺度は対象者が中規模病
院の看護管理者に限定されたものであり，また看護管
理者のコンピテンシーの一部分を評価したものであり
看護管理者の役割を効果的に果たすために鍵となるコ
ンピテンシーとは異なるものである．
先に述べたように，看護管理者のコンピテンシー構
成要素については明確にされてきたものの統一した見
解が示されておらず，測定指標の十分な検証がなされ
ていない現状にある．看護管理者のコンピテンシーが
どのように獲得され， どのような要因がコンピテンシー
を向上させるのかを明らかにするために，また，今後
の研修導入による効果を評価するためにも看護管理者
のキーコンピテンシー評価尺度の開発が急がれる．
本研究は，看護管理者のマネジメント能力の向上を
目指した効果的な組織的人材育成の方策を検討するた
めに，看護管理者の役割を効果的に果たすために鍵と
なるコンピテンシーを測定する「看護管理者のキーコ
ンピテンシー尺度」を開発することを目的とする．
Ⅱ．方
法
1．用語の定義
本研究における看護管理者とは「看護師長もしくは
主任の職位にある看護師」とする．また，キーコンピ
テンシーとは，看護管理者のコンピテンシーの中でも
「看護管理者の役割を効果的に果たすために鍵となるコ
ンピテンシー」とする．
2．研究対象
研究協力の内諾が得られた特定機能病院 42 施設お
よび 400 床以上の地域医療支援病院 60 施設に勤務す
る看護管理者 4,410 名(看護師長 2,205 名，主任 2,205
名)を対象とした．
3．調査方法
全国の特定機能病院 85 施設および 400 床以上の地
域医療支援病院の中からランダムに抽出した 120 施設
へ文書で研究協力の依頼を行い，研究協力への内諾が
得られた施設において質問紙調査を実施した．
調査票は，看護師長と主任への配布数が同数となる
ように依頼した上で，研究者から施設担当者に該当人
数分を郵送し，施設担当者から調査対象者へ配布した．
配布数は 4,410 部である．調査対象者は質問紙を受け
取った後，質問紙へ記入し，記入後は各自が返信用封
筒を用いてポストへ投函し，郵送法にて回収した．調
査期間は 2017 年 10～12 月である．
4．調査内容
1)看護管理者のキーコンピテンシーに関する項目
看護管理者の役割を効果的に果たすために鍵となる
コンピテンシーに関する具体的行動に着目し，以下の
手順で 50 項目を設定した．はじめに，看護管理者 20
名を対象に，看護管理者の役割を効果的に果たすため
に鍵と考えるコンピテンシーについて実践事例を踏ま
えて 1 人あたり 60 分程度のインタビュー調査を行っ
た．この質的データ，看護管理者のコンピテンシーの
構 成 概 念 お よ び 定 義 が 示 さ れ て い る 文 献 ( 武 村 ，
2014；虎の門病院看護部，2013；小澤・村田，2014；
井上，2014；八尾ら，2012；松下，2001；東辻ら，
2005) ，一般企業の管理者のコンピテンシーに関する文
献(佐藤，2015；西尾，2015)をもとに，看護管理経
験者(看護部長・副看護部長)6 名および看護管理学
領域の研究者 3 名で項目内容の妥当性について検討を
重ね，項目を精選した．また，看護管理者(看護師長)
5 名を対象にプレテストを行い，答えやすさの観点か
ら項目の表現を確認した．作成した 50 項目は「大変あ
てはまる」を 4 点， 「ある程度あてはまる」を 3 点， 「あ
まりあてはまらない」を 2 点， 「全くあてはまらない」
を 1 点，の 4 件法で尋ね，得点が高いほどコンピテン
シーが高いことを示している．
2)併存妥当性に用いる尺度
併存妥当性の検証には 「看護管理者のコンピテンシー
評価尺度(NACAS) 」を用いた(本村・川口，2013) ．
この尺度は 4 因子 20 項目からなり，信頼性と妥当性が
確認されている．NACAS の下位概念は「問題対処行動
CP」8 項目， 「対人関係 CP」8 項目， 「目標設定 CP」5
項目， 「情報収集 CP」4 項目で構成されている．NACAS
の 20 項目は「大変あてはまる」を 4 点， 「ある程度あ
てはまる」を 3 点， 「あまりあてはまらない」を 2 点，
「全くあてはまらない」を 1 点，の 4 件法で尋ね，得点
が高いほどコンピテンシーが高いことを示している．
NACAS の使用については，開発者の許可を得て使用
した．
3)個人属性と施設特性に関する項目
個人属性として，年齢，性別，職位，スタッフおよ
び管理者の経験年数，資格，最終学歴，看護管理者研
修を尋ねた．施設特性として，所在地，設置主体，施
設種類，施設規模，部署の看護配置基準，在院日数，
稼働率を尋ねた．
5．分析方法
回収された調査票のうち，同意確認欄にチェックが
されていないものを除き有効回答とした．
1)看護管理者のキーコンピテンシーの因子構造
「看護管理者のキーコンピテンシー」50 項目につい
て，はじめに記述統計による項目分析を行った．欠損
値(1.0%以上) ，天井効果(M + SD > 4.0) ，フロア効果
(M -SD < 1.0)を削除基準に項目を確認した．また，
項目間相関(I-I 相関；r > .80) ，Item-Total 相関分析(I-
T 相関；r < .40)を削除基準に項目を確認した．
次に，Fokkema & Greif(2017)の見解にもとづき，
日本看護科学会誌 40 巻 (2020)
看護管理者のキーコンピテンシー尺度の開発
有効回答データをランダムに 2 つのグループに分割し，
サンプルグループ 1 を用いて探索的因子分析(主因子
法，バリマックス回転)を行い，累積寄与率を確認し
た．そして，抽出された各因子において因子負荷量が
0.40 以上であり，かつ，因子負荷量が高い順から 6 項
目を採用して，再度，因子分析(最尤法，プロマック
ス回転)を行い，因子の収束性と因子間相関を確認し
た．なお，各因子を 6 項目とした理由は，今後の尺度
の活用可能性を鑑み， 調査項目の記入者負担の最小化，
各因子の同じ得点範囲による評価の容易性を考慮した
ためである．
2)妥当性の検証
構成概念妥当性は，サンプルグループ 2 を用いて確
証的因子分析を行い，モデルの適合度指標(GFI, AGFI,
CFI, RMSEA)を確認した．また，すべての有効回答
データを用いて看護管理者のコンピテンシー評価尺度
(NACAS)との相関から併存妥当性を確認した．相関
分析は各因子の得点について正規性を Shapiro-Wilk 検
定で確認したうえでスピアマンの相関係数を求めた．
さらに，職位による群間比較で基準関連妥当性を確認
した．具体的には，看護師長群と主任群に分け，それ
ぞれの分布の正規性 Shapiro-Wilk 検定で確認したうえ
で t 検定を行った．
3)信頼性の検証
信頼性は，すべての有効回答データを用いて項目全
体と抽出された因子ごとに Cronbach の α 係数で内的
整合性を確認した．
以 上 の 統 計 解 析 に は SPSS Version 24 と AMOS
Version 24 を使用し，統計学的有意水準は p < .05 とし
た．
6．倫理的配慮
本研究は，個人情報保護法および人を対象とした医
学系研究に関する倫理指針に従い，長野県看護大学倫
理委員会の審査を受け承認を得た(承認番号 2017-5) ．
対象者へは個人や施設の匿名性を保証し，調査協力の
承諾は調査票の同意欄へのチェックで同意を確認した．
調査票は，プライバシーの配慮に留意し，匿名にて行
うこと，調査への参加は対象者の意思を尊重し，研究
の参加・不参加によって不利益を被らないこと，得ら
れたデータは本研究の目的以外で使用しないこと， デー
タは統計的に処理し，厳重に保管し，分析終了後に確
実に廃棄することを文書にて説明した．分析結果につ
いては，個人が特定されない形で，学会発表や論文投
稿する旨を文書で説明した．
Ⅲ．結
果
1．対象者の個人属性および施設特性
看 護 管 理 者 2,480 名 か ら 回 答 が 得 ら れ ( 回 収 率
56.2%) ，有効回答 2,330 名(有効回答率 94.0%)を分析
対象とした．
対象者の個人属性と施設特性を表 1 に示した．対象
者の平均年齢は 48.0 歳，女性が 2,205 名(94.8%)を占
めていた．看護スタッフとしての平均経験年数は 16.7
年であり，看護管理者としての平均経験年数は 12.6 年
であった．最終学歴は 3 年課程の専門学校と看護短期
大学で 2,012 名(87.0%)を占めていた．認定看護管理
者の資格を有する者は 69 名(3.0%)であった．
施設特性として， 設置主体については国・都道府県・
市 町 村 が 648 名 ( 28.3% ) ， 国 立 大 学 法 人 が 660 名
(28.9%)を占めていた．施設種類を複数回答で尋ねた
ところ，特定機能病院，診療連携拠点病院，災害拠点
病院，臨床研修指定病院の順で多かった．
2．看護管理者のキーコンピテンシーの因子構造
記述統計による項目分析を行った結果，50 項目のう
ち欠損値，天井効果，フロア効果の削除基準に該当す
る項目はなかった(表 2) ．また，I-I 相関と I-T 相関を
分析した結果，削除基準に該当する項目はなかった．
以上の結果から，50 項目を用いてサンプルグループ
1(n = 1,160)について因子分析を行った結果，累積寄
与率 48.9%で，5 因子が抽出された(表 3) ．さらに，
各因子で因子負荷量の高い順に 6 項目を選定し，計 30
項目を用いて因子分析を行った結果，5 因子に収束し
た(表 4) ．5 因子を以下の通り命名した．
第 1 因子は，問題に直面しているときの状況把握や
情報収集とそれにもとづく問題や原因の特定を示す項
目で構成されていることから【状況認識】と命名した．
第 2 因子は，自己の言動に注意しながら他者への影響
を考慮し，相手やその場の状況に応じて，冷静にタイ
ミングよく具体的に対応する項目で構成されているこ
とから【メタ認知】と命名した．第 3 因子は，自分の
なりたい姿を明確に持ち，目標達成のために自分に求
められる役割や仕事が具体的にイメージでき，その実
現に向けて何が必要か考えて諦めず状況に応じて行動
表 1 対象者の個人属性と施設特性
全体
(N = 2,330)
看護師長
(n = 1,227)
主任
(n = 1,103)
p 値
n
%
n
%
n
%
個人属性 年齢 †
(mean ± SD)
48.0 ± 6.6
50.9 ± 5.3
44.8 ± 6.4
<.01
性別 ‡
1．男性
121
5.2%
41
3.3%
80
7.3% <.01
2．女性
2,205 94.8%
1,183
96.7%
1,022
92.7%
職位 ‡
1．看護師長・科長
1,227 52.7%
1,227 100.0%
0 100.0% <.01
2．副師長・主任
1,103 47.3%
0
0.0%
1,103
0.0%
経験年数 スタッフ †
(mean ± SD)
16.7 ± 6.2
16.1 ± 6.5
17.4 ± 5.9
<.01
管理者 †
(mean ± SD)
12.6 ± 6.4
13.6 ± 6.3
6.8 ± 4.8
<.01
資格 ‡ (複数回答)
1．看護師
2．保健師
2,273
153
97.6%
6.6%
1,195
46
97.4%
3.7%
1,078
107
97.7%
9.7%
<.01
<.01
3．助産師
160
6.9%
99
8.1%
61
5.5%
.01
4．認定看護師
207
8.9%
83
6.8%
124
11.2% <.01
5．専門看護師
27
1.2%
10
0.8%
17
1.5%
.08
6．認定看護管理者
69
3.0%
57
4.6%
12
1.1% <.01
7．その他
103
4.4%
57
4.6%
46
4.2%
.31
最終学歴 ‡
1．専門学校
1,605 69.4%
856
70.4%
749
68.3% <.01
2．看護短期大学
407 17.6%
210
17.3%
197
18.0%
3．看護大学
127
5.5%
35
2.9%
92
8.4%
4．看護系大学院(看護管理専攻)
5．看護系大学院(看護管理専攻以外)
43
85
1.9%
3.7%
36
48
3.0%
3.9%
7
37
0.6%
3.4%
6．看護系以外の大学院
46
2.0%
31
2.5%
15
1.4%
看護管理者研修 ‡
1．ファーストレベル
987 56.6%
497
44.1%
490
79.4% <.01
2．セカンドレベル
587 33.7%
558
49.6%
29
4.7%
3．サードレベル
35
2.0%
33
2.9%
2
0.3%
4．その他
134
7.7%
38
3.4%
96
15.6%
施設特性 所在地 ‡
1．北海道
164
7.1%
79
6.5%
85
7.7%
.73
2．東北
229
9.9%
119
9.7%
110
10.0%
3．関東
512 22.1%
285
23.3%
227
20.7%
4．中部
701 30.2%
360
29.5%
341
31.0%
5．近畿
372 16.0%
194
15.9%
178
16.2%
6．中国
59
2.5%
34
2.8%
25
2.3%
7．四国
70
3.0%
38
3.1%
32
2.9%
8．九州・沖縄
214
9.2%
113
9.2%
101
9.2%
設置主体 ‡
1．国
76
3.3%
49
4.1%
27
2.5%
.12
2．都道府県・市町村
572 25.0%
285
23.6%
287
26.6%
3．国立大学法人
660 28.9%
354
29.4%
306
28.4%
4．社会医療法人
34
1.5%
16
1.3%
18
1.7%
5．医療法人
121
5.3%
62
5.1%
59
5.5%
6．学校法人
255 11.2%
135
11.2%
120
11.1%
7．公益法人
89
3.9%
58
4.8%
31
2.9%
8．社会保険関連団体
7
0.3%
4
0.3%
3
0.3%
9．日本赤十字社
130
5.7%
64
5.3%
66
6.1%
10．済生会
80
3.5%
36
3.0%
44
4.1%
11．その他
261 11.4%
143
11.9%
118
10.9%
施設種類 ‡ (複数回答)
1．特定機能病院
2．地域医療支援病院
1,452 62.3%
846 36.3%
677
466
55.2%
38.0%
775
380
70.3%
34.5%
.23
.19
3．小児救急医療拠点病院
176
7.6%
105
8.6%
71
6.4%
.06
4．災害拠点病院
1,241 53.3%
669
54.5%
572
51.9%
.24
5．がん診療連携拠点病院
1,392 59.7%
747
60.9%
645
58.5%
.29
6．周産期母子医療センター
726 31.2%
406
33.1%
320
29.0%
.06
7．一般病院
224
9.6%
126
10.3%
98
8.9%
.29
8．臨床研修指定病院
989 42.4%
561
45.7%
428
38.8%
.01
9．救命救急センター
953 40.9%
524
42.7%
429
38.9%
.07
10．その他
43
1.8%
28
2.3%
15
1.4%
.12
施設規模 ‡
1．100 床未満
7
0.3%
4
0.3%
3
0.3%
.10
2．100～299 床
2
0.1%
0
0.0%
2
0.2%
3．300～499 床
62
2.7%
20
1.6%
42
3.9%
4．500～799 床
1,664 72.2%
876
72.0%
788
72.3%
5．800 床以上
571 24.8%
316
26.0%
255
23.4%
部署の看護配置 ‡
1．7 対 1
1,948 84.4%
1,004
82.5%
944
86.4%
.09
2．10 対 1
54
2.3%
30
2.5%
24
2.2%
3．その他
307 13.3%
183
15.0%
124
11.4%
部署の在院日数 †
(mean ± SD)
13.0 ± 3.9
13.1 ± 4.0
12.9 ± 3.9
.52
部署の稼働率 †
(mean ± SD)
85.4 ± 6.7
84.8 ± 6.6
86.2 ± 6.7
.46
† t 検定
‡ χ 2 検定
看護管理者のキーコンピテンシー尺度の開発
表 2 看護管理者のキーコンピテンシー 50 項目の記述統計
Mean SD
欠損値 フロア効果 天井効果
I-I 相関
I-T
相関
n % (M -SD) (M + SD) Min
Max
1 目標(あるべき姿)と現状の差異を，常に客観的事実をもとに確認している
2.9 0.5 6 0.3%
2.3
3.4
.24** -.51** .58**
2 状況の変化を見逃さないよう，多方面から情報収集し，リスクを常にモニタリングしている
2.8 0.6 7 0.3%
2.2
3.4
.20** -.55** .58**
3 直面している状況は，どの段階にあるか(問題把握の段階，原因究明の段階，手段選択決定
2.7 0.6 5 0.2%
2.1
3.3
.23** -.55** .63**
の段階，リスク対応の段階)を常に把握している
4 将来，何か不都合は生じないか，それは現状のままでいいのか，を考えて問題の洗い出しを
2.8 0.6 7 0.3%
2.2
3.4
.23** -.52** .59**
行っている
5 なぜ問題が起きたのか，その「なぜ」を繰り返し問い，原因の洗い出しを行っている
3.0 0.6 15 0.6%
2.4
3.6
.24** -.60** .61**
6 問題が起きている状況は，時間の経過(過去・現在・未来)の中で，どのような傾向(繰り
2.9 0.6 5 0.2%
2.3
3.5
.26** -.60** .59**
返し起こるなど)にあるかを捉えている
7「問題が起きている場合」と「起きていない場合」の状況の違いを確認している
2.7 0.6 6 0.3%
2.1
3.4
.22** -.52** .54**
8 原因を特定する際は，その真実を立証するための裏づけ情報を収集している
2.9 0.6 7 0.3%
2.3
3.5
.28** -.73** .63**
9 原因を特定する際は，起きている状況を分析し，全体像を把握している
3.0 0.6 7 0.3%
2.4
3.6
.30** -.73** .65**
10 山積する問題について，優先順位を「重要度」と「緊急度」で整理している
3.0 0.6 6 0.3%
2.4
3.7
.26** -.50** .61**
11 問題を「基本的な問題」 「例外的な問題」 「個別対応の問題」 「頻度が高い問題」に区分し，
2.6 0.7 13 0.6%
1.9
3.2
.20** -.45** .59**
戦略や手段を考えている
12 問題を先送りせずに，素早くタイムリーに対応している
3.0 0.6 8 0.3%
2.4
3.5
.25** -.45** .58**
13 目標の達成基準は，数値目標を用いて，具体的かつ明確に示している
2.8 0.7 21 0.9%
2.1
3.4
.22** -.46** .54**
14 問題が生じた原因に対して，どのように解決するべきかを繰り返し問い，対策を立てている
2.9 0.6 9 0.4%
2.3
3.4
.27** -.50** .63**
15 状況が変化した場合の代替の対策を立てている
2.7 0.6 8 0.3%
2.1
3.3
.21** -.50** .54**
16 目標達成のための戦略や手段を整理し，優先順位を決定している
2.9 0.6 8 0.3%
2.3
3.5
.25** -.56** .64**
17 目標達成のための戦略や手段に応じて，担当者と時間を適切に配分している
2.7 0.6 12 0.5%
2.1
3.3
.24** -.56** .60**
18 リスクを「起きる可能性が高いか」 「もし発生したならばどのような影響があるか」の 2 面か 2.8 0.6 8 0.3%
2.1
3.4
.21** -.52** .59**
ら捉えている
19 今後，問題が起きる可能性を低くするための対策を検討している
2.9 0.6 8 0.3%
2.3
3.5
.23** -.74** .56**
20 今後，問題が起きたときの影響を小さくするための対策を検討している
2.9 0.6 9 0.4%
2.3
3.5
.23** -.74** .54**
21 自分と異なる意見に対しては，一度相手の主張を受け入れてから，自分の考えを主張している 3.1 0.5 8 0.3%
2.5
3.6
.20** -.44** .46**
22 相手の主張がはっきりつかめない場合「つまりあなたの言いたいことはこういうことですか」 2.9 0.6 9 0.4%
2.3
3.6
.22** -.45** .51**
と相手の主張を明確にしてから話を進めている
23 部下からの問題提起に対して安易に回答するのではなく「あなたならどうするのか」と問い
2.9 0.6 7 0.3%
2.3
3.5
.24** -.45** .52**
かけ，自分で考えさせるようにしている
24 部下に権限委譲する際は，基本的なコンセプトを示すのみにとどめ，遂行プロセスは部下の
2.9 0.6 9 0.4%
2.3
3.5
.23** -.51** .49**
主体性を尊重している
25 多少の失敗があっても，部下の能力に応じてチャンスを与えている
3.1 0.5 7 0.3%
2.6
3.6
.24** -.52** .52**
26 明らかなミスを発見した時は，タイミングを逃がさず，その場で具体的に指摘している
3.1 0.6 7 0.3%
2.5
3.7
.27** -.52** .58**
27 部下が抱えている問題は曖昧にせず，問題が大きくならないうちに解決策を打っている
3.0 0.6 11 0.5%
2.4
3.5
.29** -.52** .62**
28 部下に忠告するときは，相手が受け入れられる感情の限度を考慮して忠告している
3.1 0.6 9 0.4%
2.5
3.7
.24** -.48** .55**
29 部下のキャリアプランを確認している
2.9 0.7 9 0.4%
2.3
3.6
.25** -.71** .58**
30 部下のキャリアプランを共有し，必要と考えられる研修を積極的に受講させている
2.8 0.7 9 0.4%
2.1
3.6
.22** -.71** .58**
31 目標達成までのプロセスにおいて，その進捗度を定期的にチェックしている
2.8 0.6 7 0.3%
2.1
3.4
.25** -.55** .60**
32 目標達成に向けて，自分の役割を認識して，自ら率先し行動している
2.9 0.6 9 0.4%
2.3
3.5
.27** -.59** .66**
33 目標達成の評価では，成果レベルをチェックし，客観的に判断している
2.9 0.6 7 0.3%
2.3
3.5
.29** -.59** .63**
34 部署目標を個人単位にブレイクダウンし，部下の能力に見合った個人目標を設定させている
2.8 0.7 8 0.3%
2.1
3.5
.24** -.51** .57**
35 部下の業務の進捗状況を把握しながら，タイムリーに仕事を分配している
2.8 0.6 10 0.4%
2.2
3.4
.23** -.40** .55**
36 納得できない意見に対して，譲歩することなく，アサーティブコミュニケーションができる
2.8 0.6 9 0.4%
2.2
3.4
.28** -.43** .57**
37 意見が対立した場合は折衷案ではなく，目標を達成するにふさわしい意見を採用している
2.8 0.6 13 0.6%
2.3
3.4
.26** -.43** .55**
38 失敗があった場合，部下のせいにするのではなく，自らの責任として対応している
3.2 0.6 9 0.4%
2.6
3.7
.23** -.52** .53**
39 患者・家族が困っている立場に遭遇したら，即座に対応している
3.3 0.5 10 0.4%
2.8
3.9
.21** -.67** .59**
40 患者・家族からの多少の理不尽な要求でも，冷静に対応している
3.2 0.6 8 0.3%
2.6
3.7
.22** -.67** .54**
41 なかなか成果があがらない場合，諦めずに絶対に成果を出すという意志をもって行動している 2.8 0.6 8 0.3%
2.2
3.4
.26** -.45** .57**
42 自らの発言と実際に取っている行動は一致している
3.0 0.5 8 0.3%
2.5
3.5
.25** -.46** .56**
43 自分の感情が他者や仕事へどのような影響を与えているかを意識して行動している
3.2 0.5 8 0.3%
2.6
3.7
.22** -.53** .52**
44 自分の強み，弱み，限界を自覚して，行動している
3.1 0.6 7 0.3%
2.5
3.7
.22** -.53** .55**
45 目標達成のために，自分に求められる役割や仕事内容が具体的にイメージできている
3.0 0.6 7 0.3%
2.4
3.6
.28** -.58** .62**
46 自分のなりたい姿を明確に持ち，その実現に向けて何が必要か考えて行動している
2.8 0.6 7 0.3%
2.2
3.4
.26** -.58** .58**
47 新しい情報や状況の変化に応じて，自らの思考や行動を変化させ，適応することができる
2.9 0.6 10 0.4%
2.3
3.5
.28** -.54** .60**
48 できる人の仕事ぶりから，そのノウハウを参考に，自分自身の行動に取り入れている
3.0 0.6 8 0.3%
2.4
3.6
.21** -.49** .52**
49 いつまでに何を完了させるべきか，締切期日を決めて，具体的に行動している
3.0 0.7 7 0.3%
2.3
3.7
.23** -.44** .57**
50 自部署の利益よりも，病院全体の利益を考えて物事を進めている
2.7 0.7 7 0.3%
2.1
3.4
.20** -.38** .54**
スピアマン相関係数 ** p < .01
表 3 看護管理者のキーコンピテンシー 50 項目の因子分析
因子
1
2
3
4
5
9 原因を特定する際は，起きている状況を分析し，全体像を把握している
.782 .249 .234 .137 .161
5 なぜ問題が起きたのか，その「なぜ」を繰り返し問い，原因の洗い出しを行っている
.758 .255 .167 .120 .127
8 原因を特定する際は，その真実を立証するための裏づけ情報を収集している
.745 .253 .180 .136 .193
6 問題が起きている状況は，時間の経過(過去・現在・未来)の中で，どのような傾向(繰り返し起こるなど) .690 .262 .118 .095 .212
にあるかを捉えている
3 直面している状況は，どの段階にあるか(問題把握の段階，原因究明の段階，手段選択決定の段階，リスク .599 .125 .253 .209 .202
対応の段階)を常に把握している
2 状況の変化を見逃さないよう，多方面から情報収集し，リスクを常にモニタリングしている
.566 .112 .243 .180 .185
4 将来，何か不都合は生じないか，それは現状のままでいいのか，を考えて問題の洗い出しを行っている
.561 .180 .246 .145 .204
7 「問題が起きている場合」と「起きていない場合」の状況の違いを確認している
.551 .242 .086 .111 .233
1 目標(あるべき姿)と現状の差異を，常に客観的事実をもとに確認している
.500 .152 .270 .243 .167
10 山積する問題について，優先順位を「重要度」と「緊急度」で整理している
.419 .228 .269 .247 .222
28 部下に忠告するときは，相手が受け入れられる感情の限度を考慮して忠告している
.167 .578 .188 .185 .073
25 多少の失敗があっても，部下の能力に応じてチャンスを与えている
.141 .573 .100 .188 .170
39 患者・家族が困っている立場に遭遇したら，即座に対応している
.183 .551 .316 .146 .007
43 自分の感情が他者や仕事へどのような影響を与えているかを意識して行動している
.143 .533 .377 .038 .026
40 患者・家族からの多少の理不尽な要求でも，冷静に対応している
.144 .516 .311 .116 .012
26 明らかなミスを発見した時は，タイミングを逃がさず，その場で具体的に指摘している
.191 .497 .188 .195 .165
23 部下からの問題提起に対して安易に回答するのではなく「あなたならどうするのか」と問いかけ，自分で
.168 .493 .094 .163 .211
考えさせるようにしている
22 相手の主張がはっきりつかめない場合「つまりあなたの言いたいことはこういうことですか」と相手の主張を .199 .493 .088 .141 .180
明確にしてから話を進めている
21 自分と異なる意見に対しては，一度相手の主張を受け入れてから，自分の考えを主張している
.137 .486 .170 .079 .139
38 失敗があった場合，部下のせいにするのではなく，自らの責任として対応している
.167 .466 .236 .181 .084
24 部下に権限委譲する際は，基本的なコンセプトを示すのみにとどめ，遂行プロセスは部下の主体性を尊重し .148 .454 .083 .204 .210
ている
36 納得できない意見に対して，譲歩することなく，アサーティブコミュニケーションができる
.167 .408 .256 .240 .226
44 自分の強み，弱み，限界を自覚して，行動している
.196 .400 .286 .044 .054
37 意見が対立した場合は折衷案ではなく，目標を達成するにふさわしい意見を採用している
.207 .381 .236 .221 .203
48 できる人の仕事ぶりから，そのノウハウを参考に，自分自身の行動に取り入れている
.194 .307 .263 .094 .126
45 目標達成のために，自分に求められる役割や仕事内容が具体的にイメージできている
.252 .253 .726 .180 .160
46 自分のなりたい姿を明確に持ち，その実現に向けて何が必要か考えて行動している
.241 .226 .677 .160 .141
47 新しい情報や状況の変化に応じて，自らの思考や行動を変化させ，適応することができる
.273 .260 .527 .158 .180
42 自らの発言と実際に取っている行動は一致している
.202 .265 .459 .149 .128
49 いつまでに何を完了させるべきか，締切期日を決めて，具体的に行動している
.217 .223 .457 .225 .164
41 なかなか成果があがらない場合，諦めずに絶対に成果を出すという意志をもって行動している
.165 .245 .445 .180 .164
50 自部署の利益よりも，病院全体の利益を考えて物事を進めている
.232 .225 .336 .249 .152
12 問題を先送りせずに，素早くタイムリーに対応している
.303 .209 .315 .235 .293
30 部下のキャリアプランを共有し，必要と考えられる研修を積極的に受講させている
.176 .284 .097 .780 .069
29 部下のキャリアプランを確認している
.170 .333 .098 .766 .049
34 部署目標を個人単位にブレイクダウンし，部下の能力に見合った個人目標を設定させている
.184 .238 .180 .695 .162
31 目標達成までのプロセスにおいて，その進捗度を定期的にチェックしている
.185 .201 .284 .533 .232
33 目標達成の評価では，成果レベルをチェックし，客観的に判断している
.248 .210 .324 .460 .270
13 目標の達成基準は，数値目標を用いて，具体的かつ明確に示している
.269 .114 .274 .440 .200
32 目標達成に向けて，自分の役割を認識して，自ら率先し行動している
.264 .246 .306 .386 .245
27 部下が抱えている問題は曖昧にせず，問題が大きくならないうちに解決策を打っている
.217 .272 .218 .384 .209
35 部下の業務の進捗状況を把握しながら，タイムリーに仕事を分配している
.163 .265 .300 .313 .272
.750
20 今後，問題が起きたときの影響を小さくするための対策を検討している
.306 .215 .124 .094
19 今後，問題が起きる可能性を低くするための対策を検討している
.335 .213 .144 .106 .732
18 リスクを「起きる可能性が高いか」 「もし発生したならばどのような影響があるか」の 2 面から捉えている
.404 .205 .141 .124 .519
15 状況が変化した場合の代替の対策を立てている
.333 .174 .157 .189 .473
17 目標達成のための戦略や手段に応じて，担当者と時間を適切に配分している
.299 .164 .279 .308 .419
16 目標達成のための戦略や手段を整理し，優先順位を決定している
.377 .136 .354 .299 .406
14 問題が生じた原因に対して，どのように解決するべきかを繰り返し問い，対策を立てている
.328 .226 .210 .224 .402
11 問題を「基本的な問題」 「例外的な問題」 「個別対応の問題」 「頻度が高い問題」に区分し，戦略や手段を
.329 .166 .219 .209 .346
考えている
寄与率
11.4 10.2 9.9
8.9
8.4
累積寄与率
11.4 21.7 31.6 40.5 48.9
サンプルグループ 1(n = 1160)について，主因子法，バリマックス回転を実施
日本看護科学会誌 40 巻 (2020)
看護管理者のキーコンピテンシー尺度の開発
表 4 看護管理者のキーコンピテンシー 30 項目の因子分析
因子
1
2
3
4
5
5 なぜ問題が起きたのか，その「なぜ」を繰り返し問い，原因の洗い出しを行っている
.801
.072 -.069 -.019 -.054
9 原因を特定する際は，起きている状況を分析し，全体像を把握している
.756
.052
.036
.004 -.028
8 原因を特定する際は，その真実を立証するための裏づけ情報を収集している
.756
.037 -.051 -.023
.061
6 問題が起きている状況は，時間の経過(過去・現在・未来)の中で，どのような傾向(繰り返し起こる
.717
.051 -.100 -.020
.095
など)にあるかを捉えている
3 直面している状況は，どの段階にあるか(問題把握の段階，原因究明の段階，手段選択決定の段階，
.622 -.125
.252
.005 -.068
リスク対応の段階)を常に把握している
2 状況の変化を見逃さないよう，多方面から情報収集し，リスクを常にモニタリングしている
.523 -.078
.148
.061
.009
40 患者・家族からの多少の理不尽な要求でも，冷静に対応している
.022
.660
.035 -.032
.038
39 患者・家族が困っている立場に遭遇したら，即座に対応している
.098
.649 -.001
.071 -.061
43 自分の感情が他者や仕事へどのような影響を与えているかを意識して行動している
-.066
.577
.288 -.115 -.009
28 部下に忠告するときは，相手が受け入れられる感情の限度を考慮して忠告している
-.033
.540
.001
.169
.038
26 明らかなミスを発見した時は，タイミングを逃がさず，その場で具体的に指摘している
.087
.447 -.021
.132
.112
25 多少の失敗があっても，部下の能力に応じてチャンスを与えている
-.019
.434 -.019
.158
.142
45 目標達成のために，自分に求められる役割や仕事内容が具体的にイメージできている
-.035
.081
.831 -.082 -.075
46 自分のなりたい姿を明確に持ち，その実現に向けて何が必要か考えて行動している
.015
.023
.781 -.072 -.113
47 新しい情報や状況の変化に応じて，自らの思考や行動を変化させ，適応することができる
.084
.137
.616 -.089 -.064
41 なかなか成果があがらない場合，諦めずに絶対に成果を出すという意志をもって行動している
-.084
.278
.484 -.034
.023
49 いつまでに何を完了させるべきか，締切期日を決めて，具体的に行動している
.070
.082
.476
.076 -.055
42 自らの発言と実際に取っている行動は一致している
.005
.320
.437 -.041 -.036
30 部下のキャリアプランを共有し，必要と考えられる研修を積極的に受講させている
.007
.066 -.145
.901 -.106
29 部下のキャリアプランを確認している
-.010
.098 -.122
.877 -.103
34 部署目標を個人単位にブレイクダウンし，部下の能力に見合った個人目標を設定させている
.035
.016
.045
.620 -.002
13 目標の達成基準は，数値目標を用いて，具体的かつ明確に示している
.045 -.075
.236
.571
.166
31 目標達成までのプロセスにおいて，その進捗度を定期的にチェックしている
-.078 -.039
.299
.498
.049
33 目標達成の評価では，成果レベルをチェックし，客観的に判断している
-.009 -.013
.295
.401
.111
.949
20 今後，問題が起きたときの影響を小さくするための対策を検討している
-.068
.075 -.124 -.082
19 今後，問題が起きる可能性を低くするための対策を検討している
.017
.031 -.107 -.053
.877
18 リスクを 「起きる可能性が高いか」 「もし発生したならばどのような影響があるか」 の 2 面から捉えている
.138
.020
.057 -.051
.572
15 状況が変化した場合の代替の対策を立てている
.108 -.038
.205
.021
.490
16 目標達成のための戦略や手段を整理し，優先順位を決定している
.107 -.121
.201
.134
.451
17 目標達成のための戦略や手段に応じて，担当者と時間を適切に配分している
-.001 -.122
.235
.158
.423
因子間相関
因子 1【状況認識】
1
因子 2【メタ認知】
.51
1
因子 3【自己管理】
.67
.58
1
因子 4【キャリア支援】
.54
.55
.66
1
因子 5【意思決定】
.69
.42
.62
.57
1
サンプルグループ 1(n = 1160)について，最尤法，プロマックス回転を実施
する項目で構成されていることから【自己管理】と命
名した．第 4 因子は，部下のキャリアプランを共有し，
目標設定や進捗状況を確認し，課題解決や目標達成に
向けてサポートする項目で構成されていることから
【キャリア支援】と命名した．第 5 因子は，目標達成の
ための戦略や手段を複数検討し，最適なものを選択し
てタスク配分する，また，影響の最小化や代替案の検
討などリスク対応を検討する項目で構成されているこ
とから【意思決定】と命名した．
3．妥当性の検証
サンプルグループ 2(n = 1150)を用いた 5 因子 30
項目のモデルの適合度指標は GFI = .907，AGFI = .899，
CFI = .921，RMSEA = .047 であった(図 1) ．また，今
回抽出された 5 因子と NACAS の下位概念との相関を
求めた結果，r = .34～.63(p < .01)であった(表 5) ．
さらに，看護師長群と主任群の得点を群間比較した結
果，5 因子すべてにおいて看護師長群の得点が有意に
高かった(表 6) ．
図 1 看護管理者のキーコンピテンシーのパス図
サンプルグループ 2(n = 1150) ．
〇は潜在変数，□は観測変数(Q は項目番号)を示す．
誤差変数は省略．
表 5 看護管理者のキーコンピテンシー尺度と看護管理者の
コンピテンシー評価尺度(NACAS)との相関
看護管理者のコンピテンシー評価尺度
(NACAS)
問題対処
行動 CP
対人関係
CP
目標設定
CP
情報収集
CP
因子 1 状況認識
.63**
.41**
.63**
.51**
因子 2 メタ認知
.50**
.56**
.49**
.44**
因子 3 自己管理
.58**
.45**
.59**
.48**
因子 4 キャリア支援
.51**
.40**
.57**
.43**
因子 5 意思決定
.54**
.34**
.56**
.45**
スピアマン相関係数 ** p < .01
確認された．
表 6 職位群別の看護管理者のキーコンピテンシー尺度得点
の比較
看護師長
(n = 1,205)
主任
(n = 1,099)
p 値
mean
SD
mean
SD
因子 1 状況認識
17.7
2.8
16.8
2.7
<.01
因子 2 メタ認知
19.3
2.5
18.6
2.3
<.01
因子 3 自己管理
17.8
2.7
17.2
2.5
<.01
因子 4 キャリア支援 18.0
2.7
15.8
2.8
<.01
因子 5 意思決定
17.3
2.7
16.4
2.6
<.01
t 検定
Ⅳ．考
察
1．看護管理者のキーコンピテンシーの因子構造
本結果より，看護管理者のキーコンピテンシーは 5
因子構造【状況認識】 【メタ認知】 【自己管理】 【キャリ
ア支援】 【意思決定】であることが確認された．
今回，明らかになった【状況認識】は問題に直面し
ているときの状況把握や問題や原因を特定するための
情報収集に関するコンピテンシーであり， 【意思決定】
は目標達成のための方策について起こりうるリスクを
吟味し最適なものを選択するコンピテンシーである．
また【状況認識】と【意思決定】の因子間相関は比較
的高い結果を示しており，これらの因子は連動して起
こるものと考えられ，この一連の過程は問題解決能力
と言える．中小規模病院の病院長，事務部門長，看護
部門長を対象とした調査結果では看護管理者に求めら
れる能力として「問題解決」が上位にあげられており
(手島ら，2016) ， 【状況認識】と【意思決定】は看護管
理者のキーコンピテンシーとして妥当であると考える．
また，看護管理者のコンピテンシーの構成要素として，
既存の研究成果では「分析的思考」 (武村，2014；虎の
門病院看護部，2013；松下，2001)「概念化(課題設
定力) 」 (武村，2014)もしくは「概念
，
化思考」 (虎の門
病院看護部，2013) ， 「情報収集」 (本村・川口，2013)
もしくは「情報収集・処理能力」 (八尾ら，2012；東辻
ら，2005)が提示されており，これらは本研究の【状
況認識】と【意思決定】に該当するものと考える．
【メタ認知】は自己の言動に注意しながら他者への影
響を考慮し，相手やその場の状況に応じて，冷静に対
応するコンピテンシーである．この【メタ認知】は既
存研究で示された看護管理者のコンピテンシーの構成
要素のうち，他者とのかかわりという点においては「コ
ミュニケーション能力」 ( 八尾ら ， 2012 ； 東辻ら ，
2005)や「対人関係」 (本村・川口，2013)に該当する
と考えられるが，これらと大きく異なる点がある．そ
れは他者とのかかわりの前提に自分自身を客観的に捉
える視点を持つことである．つまり，看護管理者は患
者や家族，部下とのかかわりにおいて，相手の言動に
一喜一憂するのではなく，自己の感情を客観視して冷
静な対応が求められ， 【メタ認知】はこの内容を反映し
たコンピテンシーであると考える．
そして， 【自己管理】は自分自身のキャリアビジョン
を明確に持ち，その実現に向けて諦めずに状況に応じ
て行動するコンピテンシーであり， 【キャリア支援】は
部下の目標設定や進捗状況を確認し，課題解決や目標
達成に向けてサポートするコンピテンシーである．主
に前者は「信念の維持」 (武村，2014)や「自己研鑽・
学習力」 ( 武村，2014 ) ， 後者は 「 育成力」 ( 武村，
2014)「部下へ動機づけ」 (東辻ら，2005)「能力開
発」 (井上
，
，2014)を網羅している内容であり，
，
いずれ
も看護職員の資質向上には必要不可欠なコンピテン
シーである．看護管理者の役割とは「安全かつ質の高
い看護を継続的かつ一貫性をもって提供する．良質な
看護を提供するために，看護職員が看護実践能力を保
持し，十分に能力を発揮して働き続けられる教育的環
境を整え，各人の成長と職業上の成熟を支援する． 」と
される(日本看護協会，2016) ．看護管理者は，単に役
割をこなすだけではなく，この役割をどのようにこな
すかが良質な看護の提供や看護職員の資質向上に関係
してくると考える．看護管理者は自らが明確なビジョ
ンを持ち，率先垂範する姿勢を見せ，部下が十分に看
護実践能力を発揮して働き続けられる教育的環境を整
えていくことが求められており， 【自己管理】と【キャ
リア支援】は看護管理者のキーコンピテンシーとして
妥当であると考える．
2．開発した尺度の信頼性・妥当性の検証
5 因子 30 項目から構成される尺度の妥当性について
は，構成概念妥当性，併存妥当性，基準関連妥当性の
検証を行った．構成概念妥当性について，モデル適合
り，併存妥当性を支持する結果であったと考える．基
準関連妥当性について，職位別比較を行った結果，看
護師長群は主任群より有意に高い得点を示し，基準関
連妥当性を支持する結果であったと考える．
5 因子 30 項目から構成される尺度の信頼性につい
れ(村上，2006) ，本尺度の内的整合性は確保されたと
考える．
3．本研究の限界と今後の課題
本研究の対象は，全国から抽出した大規模サンプリ
ングによって得られたものであり，看護管理者の属性
については看護管理者を対象とした既存の全国規模の
調査結果(日本看護協会，2014；手島ら，2016)と比
べても看護管理者となった年齢，看護管理経験年数な
どにおいて大差はなく，施設の所在地，設置主体，施
設種類についてもほぼ同様の結果であり，概ね母集団
を反映した結果であると考える．しかし，本研究は大
規模病院に勤務する看護管理者を対象に限定してお
り，中小規模病院の看護管理者への適応可能性につい
てはさらなる検証が必要である．また，本研究は
COSMIN チェックリスト(2019)に示されている推奨
事項をすべて満たすことはできなかった．中でも，再
検査信頼性・測定誤差については，研究デザイン上，
検証することはできなかったが，COSMIN の 3 つのド
メインである信頼性，妥当性，反応性を総合的に判断
しても適切な尺度を開発することができたと言える．
今回，5 因子 30 項目からなる尺度の信頼性と妥当性
が確認できた．看護管理者の役割を果たすために鍵と
なるコンピテンシーは 5 因子構造であることが示され
たため，今後はこの 5 つのキーコンピテンシーの向上
に資する効果的な組織的支援のあり方について検討し
ていく．
Ⅴ．結
論
J. Jpn. Acad. Nurs. Sci., Vol. 40, 2020
| [
-0.03307001292705536,
-0.0914469063282013,
-0.05744044482707977,
0.014289068058133125,
-0.11607842147350311,
-0.017258157953619957,
-0.08818225562572479,
0.04419282451272011,
0.05408871918916702,
0.060737188905477524,
0.10356400907039642,
-0.035734571516513824,
0.056379206478595734,
0.0975... |
0123456789
Delphine Bertram
Lucia Cea-Soriano
Herbert S. Chase
Priya Bahri
The Netherlands Subhrojyoti BhowmickThe Netherlands, India, Canada, Spain, USA
Floriana De Angelis
Cristina de la Calle
Fernando de Mora
Olatz P. de Viñaspre
Sieta T. de Vries
Thomas Frisell
Galal Galal-Edeen
Dick Lindhout
Patricia D-C. Mastroianni
Géric Maura
Nazia Chaudhuri
Sweden Kin-Wah W. Fung, The Netherlands Feifan LiuXiaoyi Chen, AnthonyWisit Cheungpasitporn, W. FoxUK, France, USA, UK, Spain, Spain, Spain, The Netherlands, UK, UK, USA, UK, The Netherlands, USA, USA, Brazil, France
Claire K. McLintock, New Zealand Andreas D. Meid, Germany Brittany L. Melton
Patricia McGettigan
Mitchell McGillUK, USA, USA
Jenna M. Reps
Peter R. Rijnbeek
The Russian Federation Anton Pottegård
Shahrul Mt-Isa
UK, Congo, Denmark, UK, The Netherlands, UK
Joep H.G. Scholl
Patrick Souverein
Lavinia Schüler-Faccini
Tania Schink
The Netherlands Lynn M. Schriml, The Netherlands Rosangela SpigaItaly Julia SpoendlinGermany, USA, Brazil, USA
012345678910.1007/s40264-020-01019-x
Denmark Linda Härmark, The Netherlands Manfred Hauben, USA Martin E.W. Hemels, The Netherlands Séverine Henrard, Belgium Thomas Herdegen, Germany Nelia Hernandez, Uruguay Samuel Heyman, Israel Alan M. Hochberg, Switzerland Corinne M. Hohl, Canada Luc M.V. Hondeghem, Belgium M. Yves Horsmans, Belgium Daniel B. Horton, USA Bruce P.J. Hugman, Thailand Takuya Imatoh, Japan Pedro Inacio, Finland Magnus Ingelman-Sundberg, Sweden Ambrose O. Isah, Nigeria Irina Isakova-Sivak, The Russian Federation Jo-Hanna Ivers, Ireland Yogini Jani, UK Joseph A.M. Janssen, The Netherlands Narumol Jarernsiripornkul, Thailand Tianze Jiao, Canada Zhaohui Jin, USA Reed Johnson, USA Kerina Jones, UK Cheng Ju, USA Eliangiringa A. Kaale, United Republic of Tanzania Masayuki Kaneko, Japan Alan Kaplan, Canada Sigal Kaplan, Israel Igor Karp, Canada Alison T. Kawai, USA Susan Keam, New Zealand Erin Kelty, AustraliaLucie M. Gattepaille, Sweden
Milo Gatti, Italy
Alexander Gerbes, Germany
David Gerrett, UK
Rosa Gini, Italy
Thomas Goedecke, UK
Fernando Gomez-Peralta, Spain
Dharmesh Gopalakrishnan, USA
Amandine Gouverneur, France
Matthew Grainge, UK
Birgitta Grundmark, Sweden
Sinem Ezgi Gulmez, Turkey
Ahmet Güner, Turkey
Gery P. Guy Jr, USA
Maya B. Habre, Lebanon
Eelko Hak, The Netherlands
Gillian C. Hall, UK
Christine E. Hallgreen,
The COVID-19 pandemic has reinforced the importance of rapid and wide dissemination of high-quality information. Springer Nature is supporting the global response to COVID-19 by making all relevant content immediately and freely available. Indeed, Drug Safety has published a number of papers relevant to the COVID-19 pandemic that are free to access.The high quality of the content published in Drug Safety has been reflected in the most recent impact factor of 3.442, placing the journal in Q1 of Public, Environmental & Occupational Health category and in Q2 of Pharmacology & Pharmacy and Toxicology categories. Drug Safety has published content in a timely manner, with an average time from submission to first decision of 15 days.We do hope that you have found the articles published throughout the year in Drug Safety to be interesting and informative. The editorial schedule for 2021 is well under way, and we are looking forward to bringing you many high-quality and authoritative articles over the coming year. I thank you for your continued support.With best wishes, Nitin Joshi Editor-in-Chief, Drug Safety | [
0.09189356863498688,
-0.08954815566539764,
-0.0777827575802803,
0.06366841495037079,
0.032775841653347015,
0.03756970912218094,
-0.09936890006065369,
0.12319180369377136,
-0.03025749698281288,
0.035245124250650406,
0.0472220815718174,
0.054232802242040634,
-0.02109638974070549,
0.109842643... |
グラム陽性細菌の薬剤耐性と感染制御 野 口 雅 久 Antimicrobial Resistance and Infection Control for Gram-positive Bacteria
235. 2021
本総説は，2019
に記述したものである．
グラム陽性細菌の薬剤耐性と感染制御 野 口 雅 久 Antimicrobial Resistance and Infection Control for Gram-positive Bacteria
YAKUGAKU ZASSHI
1412235. 2021(Received October 8, 2020)235 東京薬科大学薬学部病原微生物学教室(〒192 0392 東 京都八王子市堀之内 1432 1) -Review-antimicrobial resistanceStaphylococcus aureusplasmidinfection control
Antimicrobial resistance (AMR) is a serious problem worldwide. We searched for the AMR determinants of various bacteria isolated from clinical settings and studied their resistance mechanisms and molecular epidemiology. This review focuses on the AMR of Staphylococcus aureus, a major gram-positive pathogen, which has the ability to acquire resistance to antimicrobials. The resistance factors of S. aureus are frequently found on mobile elements, including plasmids and transposons. We determined the complete DNA sequence of the tetracycline-resistance plasmid and found that the inducible expression of tetK in S. aureus was regulated by a post-transcriptional attenuation mechanism. Furthermore, outbreaks of methicillin-resistant S. aureus (MRSA) in hospitals and communities have led us to study infection controls, including the antiseptic susceptibility evaluation and molecular epidemiology of MRSA. Various antiseptic resistance determinants, such as qacA/B and smr, were identiˆed on plasmids and characterized. We demonstrated that the plasmid-mediated eOEux pump QacB variant QacIII confers ‰uoroquinolone eOEux ability to S. aureus. Studies on MRSA epidemiology had shown that community-acquired MRSA (CA-MRSA) was disseminated into hospitals and that an increased use of alcohol-based rubs could reduce the incidence of MRSA infections in such institutions. Additionally, the study of CA-MRSA collected from communities and hospitals showed an increase in Panton-Valentine leucocidin (PVL)-positive CA-MRSA, causing severe skin and soft tissue infections. Moreover, various PVL-positive CA-MRSA clones have disseminated in Japan, whereas the USA300 LV/J clone evolved in that country. Our study provides important information regarding MRSA infection control.
遺伝子 cat や TC 耐性遺伝子 tetK などは，リプレッ サーをコードする調節遺伝子が存在しない． 8 10) 代 わりに，構造遺伝子上流に，小さなぺプチドをコー ドするリーダー遺伝子とヘアピン構造を形成可能な 塩基配列が存在した(Fig. 2) ．調節は，転写でな く，tetK-mRNA が特異的なコンフォメーション構 造を形成し，tetK 構造遺伝子のリボソーム結合部 位 (ribosome-binding site; RBS) 2 がマスクされる． その結果，リボソームの結合が阻害され，さらに裸 の tetK-mRNA の分解が進行し，TetK タンパク質 の合成が抑制される．TC がリボソームに結合して リーダー領域のタンパク質合成を阻害すると， tetK-mRNA のコンフォメーションが変化し，tetK 構造遺伝子のリボソーム結合部位(RBS2)が露出 し，リボソームが結合して，TetK のタンパク質合 成が進行する．筆者は，ermC や cat86 で提唱され た posttranslational attenuation mechanism に 類 似 していること明らかにした 9,10) ．さらに，これらの 手法を用いて，クロラムフェニコール耐性プラスミ ド pTZ12，アミノグリコシド耐性遺伝子 aadK，マ クロライドリン酸化酵素 mphA などの遺伝子を見 つけ，その遺伝子構造と耐性メカニズムを明らかに した． 11 15) また，TetK タンパク質の高発現系を開 発 し ， TetK タ ン パ ク 質 の 構 造 の 解 明 に 貢 献 し た． 16,17) これらの耐性遺伝子とプラスミドを組換え て，グラム陽性菌のベクターや大腸菌とのシャトル ベクターを構築した． 11, 18 20)
1989 年，Bacillus 属由来誘導性クロラムフェニ
コ ー ル 耐 性 遺 伝 子 cat86 の 発 現 を 研 究 し て い た Maryland 大学の Lovett 教授の下にポスドクとして 留学し，cat の遺伝子発現を研究する機会が得られ た．この研究で，枯草菌では終止コドン UGA がト リプトファンとして解読される readthrough 現象を 明らかとし， 21) 20 年後の筋ジストロフィー薬の開発 研究につながった． 22) 一方，枯草菌 ATCC6633 は，抗菌薬に感受性と して知られ，抗生物質の力価検定の標準株として使 用されている．ところが，ストレプトマイシンをわ ずかに不活化することを見い出した． 23) 枯草菌の染 色体上における薬剤耐性遺伝子の検索を行い，アミ ノグリコシド不活化酵素をコードする遺伝子 aadK をクローニングし，それらの遺伝子マップを含めた 遺伝子を同定した． 13,24) その後，枯草菌の全ゲノム シーケンスが決定され，筆者の結果がサポートされ た．また，相同性組換えを応用した insertion inacti- vation 法で作製した knockout 株は，ストレプトマ イシンに超感受性化した． 13) これらの研究から，土 壌細菌が薬剤耐性関連遺伝子の拡散におけるリザー バーとなっている可能性が示された． 4. プラスミド性消毒薬低度耐性遺伝子の解析 1990 年頃から，日本の院内でセフェム系薬に耐 性を示す多剤耐性黄色ブドウ球菌，いわゆるメチシ リ ン 耐 性 黄 色 ブ ド ウ 球 菌 ( methicillin-resistant
Fig. 2 .
2Hypothetical Secondary Structure of the Control Region of the tet(K) mRNA 5-end The mRNA sequence was deduced from pNS1 DNA sequence. 6) Structures [A], and [B] correspond to the inactive and active forms, respectively. RBS1 and SBS2 refer to the ribosome binding sites for the translation of the leader and the tetracycline-resistance protein (TET), respectively.
Fig. 3 .た．
3Transmembrane Structure of QcaA, and Antiseptic Susceptibility of Staphylococcus aureus Carrying the qacA/B Genes MIC, minimum inhibitory concentration; AF, acri‰avin; BKC, benzalkonium chloride; CHG, chlorhexidine digluconate; CV, crystal violet; DA, diminazene aceturate; EB, ethidium bromide; PI, pentamidine isethionate; , none; A, alanine; D, aspartic acid; E, glutamic acid; G, glycine; I, isoleucine; S, serine; T, threonine; V, valine. The amino acid sequence of QacBI of pSK23 was obtained from Paulsen et al. 45 47) これに伴 い，病院内における PVL 陽性 MRSA の分離頻度も増加していることが明らかと なった． 47,48) また，院内の PVL 陽性株は市中の菌 株よりも多様性を示し，USA300 clone を中心に少 なくとも 7 種の clones が流行していることが明ら かとなった． 49 51) それらのうち，全ゲノム解析から， USA300-LV/J clone と CUSA300 clone は，日本で 独自に進化した PVL 陽性 MRSA であることが示 唆された． 49,51) さらに，これまでに収集した PVL 陽 性 MRSA の 各
黄色ブドウ球菌(Staphylococcus aureus )は，グ ラ ム陽 性 球 菌 で コア グ ラ ー ゼ を 産生 す る ． 1) 16Sはじめに
筆者は，細菌の薬剤耐性と感染制御に関する研究
を DNA 解析の手法を用いて行ってきた．これら
は，病院やクリニックの患者(臨床)から分離され
た黄色ブドウ球菌，肺炎球菌，ヘリコバクター・ピ
ロリ，大腸菌，緑膿菌，アクネ菌などから薬剤耐性
遺伝子を検索して，遺伝子の同定，耐性機序と耐性
伝播の解明，薬剤感受性試験による有効な抗菌薬の
検索等により，感染症治療と感染制御の一助となる
医療系の研究であり，当時の基礎薬学系では異端で
あった．本総説は，2019 年度退職にあたり在職中
の研究，黄色ブドウ球菌を代表とするグラム陽性菌
の薬剤耐性の変遷について，筆者の研究の歩みとと
もに記述する．
1. 黄色ブドウ球菌
rRNA 塩基配列に基づく系統分類では，ファーミ
キューテス門，バシラス網，バシラス目，ブドウ球
菌科に属する．本菌は毒素のデパートと称され，表
皮剥脱毒素，エンテロトキシン，溶血毒素，白血球
破壊毒素，毒素性ショック症候群毒素などの種々の
毒素や病原性因子を産生する菌株が存在する．その
ため，約 49 種のブドウ球菌の中で最も病原性が高
い．通常，ヒト由来コアグラーゼ陽性菌はほとんど
が黄色ブドウ球菌であることから，臨床では，便宜
上，コアグラーゼ陽性ブドウ球菌 (黄色ブドウ球菌)
野口雅久
1978 年東京薬科大学卒業後，同大学大
学院院進学，理化学研究所研究生．83
年博士課程修了，薬学博士取得．同年
同大学助手，Maryland 大学留学，講
師，准教授を経て，2012 年病原微生物
学教室教授．20 年名誉教授，同大学客
員教授，明星大学理工学部非常勤講師．
236
YAKUGAKU ZASSHI
Vol. 141, No. 2 (2021)
とコアグラーゼ陰性ブドウ球菌(coagulase negative
staphylococci; CNS)に二分されている．代表的な
化膿性疾患の起炎菌であり，産生する毒素によって
食中毒，皮膚・軟部組織感染症，肺炎，敗血症など
様々な感染症に関与する．一方，皮膚常在菌として
も知られ，約 30％の健常者の鼻腔内からも分離さ
れる．薬剤耐性を獲得し易く，代表的な院内感染原
因菌として，本菌の流行が院内感染の指標となって
いる．
2. 黄色ブドウ球菌の薬剤耐性プラスミド
学部学生時に，米国カリフォルニアのスタン
フォード大学を中心に DNA 組換え実験が発表され
た．組換え DNA 実験の潜在的な危険性(バイオハ
ザード)が指摘され，1975 年に科学者自らが研究
を制限し，社会的責任を問うたことで科学史に残る
アシロマ会議が開催された． 2) この分子生物学の創
成期に，組換え DNA 研究を知り，研究者の道を志
した．ところが，1970 年代において，薬系大学で
は DNA を研究していたのは主に有機化学系の研究
室であった．1976 年，東京薬科大学は女子部と男
子部が八王子キャンパスに移転したが，これにより
偶然，女子部の第二微生物学教室(現：病原微生物
学教室)の笹津備規先生らが黄色ブドウ球菌の薬剤
耐性プラスミドを用いて枯草菌(Bacillus subtilis )
を形質転換したことが話題となっていたことを知っ
た． 3) そこで，この教室の大学院生になり，黄色ブ
ドウ球菌の薬剤耐性の研究を始めた．
当時は，プラスミド DNA を遺伝情報などの生物
活性を持つ完全な分子として精製する技術や情報が
未成熟であった．そのため，放射性物質で DNA を
標識後，密度平衡勾配遠心によって分離，標識され
たプラスミド DNA 分画を集め，透過型電子顕微鏡
でプラスミド分子を確認して，大きさを測定すると
いった煩雑な方法が取られ，1 ヵ月ほど要してい
た．その精製したプラスミドを枯草菌に取り込ま
せ，耐性を発現させた実験は，プラスミド DNA が
生物活性を持つことを証明した画期的な実験であっ
た． 3,4) しかし，薬剤耐性プラスミドの遺伝子構造を
解析することは非常に困難であったため，病原細菌
の遺伝子を用いることの安全性が危惧されていた．
そこで，黄色ブドウ球菌の薬剤耐性プラスミドをグ
ラム陽性菌における安全なベクターとして開発する
ため，制限酵素を含めた DNA 関連酵素を研究して
いた理化学研究所(理研)の安藤忠彦主任の微生物
学研究室の研究生になることを条件に博士課程に進
学した．理研では，アシロマ会議に参加した宍戸和
夫先生(東京工業大学名誉教授)から直接指導を受
けた．
3. 薬剤耐性プラスミドのゲノム解析
理研において，黄色ブドウ球菌の小型のテトラサ
イクリン(tetracycline; TC)耐性プラスミド pTZ5
(旧名：pTP-5)の遺伝子解析に取り組んだ．当時
は，DNA 塩基配列決定法は普及しておらず，解析
を行う第 1 段階として，制限酵素の地図作成を行っ
た． 5) この地図を基に，制限酵素断片を欠損させ，
それらを枯草菌に導入し，TC 耐性発現とプラスミ
ドの細胞内保持(複製能)を調べ，TC 耐性遺伝子
と複製遺伝子をマッピングした．同時に生物活性を
有する最小の TC 耐性プラスミド pNS1 を作製した
( Fig. 1 ) ． 5) Maxam と Gilbert の 化 学 分 解 に よ る
DNA 塩基配列決定法が発表され，理研において，
DNA 塩基配列決定法のシステム構築と pNS1 の全
塩基配列決定の研究を開始した．Maxam・Gilbert
法は，制限酵素切断末端から 200 300 塩基しか決定
できず，解析した塩基配列は穴だらけであったが，
サンガーが開発した Dideoxy 法を併用することで 3
年を要して，全塩基配列を決定した． 6) ところが，
いち早く，米国の Khon らが TC 耐性プラスミド
pT181(4.4 kb)の全塩基配列を発表した． 7) pNS1
は pT181 と 99.5％の相同性を示していたため，競
争には負けてしまった．しかし，彼らの報告した
TC 耐性遺伝子 tetK は 1 塩基の間違いがあり，のち
に筆者の tetK が正しいことが証明された．tetK の
発現は TC によって誘導される．大腸菌の tetA，
tetB などはラクトースオペロンと同様に，tet 構造
遺伝子上流に存在する調節遺伝子 tetR から産生さ
れるリプレッサーによって負の転写制御を受けてい
る．しかし，黄色ブドウ球菌で見つかったマクロラ
イド耐性遺伝子 ermC，クロラムフェニコール耐性
Fig. 1. Restriction and Gene Maps of Plasmid pNS1
Arrows show gene regions and transcription direction. P, promoter; T,
terminator; tet, tetracycline-resistance gene tetK; repC, replication gene;
orfC, open reading frame C.
. S Lakhundi, K Zhang, Clin. Microbiol. Rev. 31Lakhundi S., Zhang K., Clin. Microbiol. Rev., 31, e00020-18 (2018).
P Berg, D Baltimore, S Brenner, R O Roblin, Iii, M F Singer, Proc. Natl. Acad. Sci. USA. Natl. Acad. Sci. USA72Berg P., Baltimore D., Brenner S., Roblin R. O. III, Singer M. F., Proc. Natl. Acad. Sci. USA, 72, 1981 1984 (1975).
. M Kono, M Sasatsu, H Hamashima, Microbios Lett, 5Kono M., Sasatsu M., Hamashima H., Micro- bios Lett., 5, 55 59 (1977).
S D Ehrlich, Proc. Natl. Acad. Sci. USA. Natl. Acad. Sci. USA74Ehrlich S. D., Proc. Natl. Acad. Sci. USA, 74, 1680 1682 (1977).
. N Noguchi, K Shishido, T Ando, M Kono, Gene. 21Noguchi N., Shishido K., Ando T., Kono M., Gene, 21, 105 110 (1983).
. N Noguchi, T Aoki, M Sasatsu, M Kono, K Shishido, T Ando, FEMS Microbiol. Lett. 37Noguchi N., Aoki T., Sasatsu M., Kono M., Shishido K., Ando T., FEMS Microbiol. Lett., 37, 283 288 (1986).
. S A Khan, R P Novick, Plasmid. 10Khan S. A., Novick R. P., Plasmid, 10, 251 259 (1983).
. T Aoki, N Noguchi, M Sasatsu, M Kono, Gene. 51Aoki T., Noguchi N., Sasatsu M., Kono M., Gene, 51, 107 111 (1987).
. M Mayford, B Weisblum, J Embo, 8Mayford M., Weisblum B., EMBO J., 8, 4307 4314 (1989).
. P S Lovett, Gene, 179Lovett P. S., Gene, 179, 157 162 (1996).
. M Kono, T Aoki, M Sasatsu, N Noguchi, K O'hara, Agric. Biol. Chem. 49Kono M., Aoki T., Sasatsu M., Noguchi N., O'hara K., Agric. Biol. Chem., 49, 1429 1433 (1985).
. N Noguchi, K Ohmiya, T Tanaka, K O'hara, M Kono, Agric, Biol. Chem. 53Noguchi N., Ohmiya K., Tanaka T., O'hara K., Kono M., Agric. Biol. Chem., 53, 2519 2520 (1989).
. N Noguchi, M Sasatsu, M Kono, FEMS Microbiol. Lett. 114Noguchi N., Sasatsu M., Kono M., FEMS Microbiol. Lett., 114, 47 52 (1993).
. N Noguchi, A Emura, H Matsuyama, K O'hara, M Sasatsu, M Kono, Antimicrob. Agents Chemother. 39Noguchi N., Emura A., Matsuyama H., O'Hara K., Sasatsu M., Kono M., An- timicrob. Agents Chemother., 39, 2359 2363 (1995).
. N Noguchi, J Katayama, K O'hara, FEMS Microbiol. Lett. 144Noguchi N., Katayama J., O'Hara K., FEMS Microbiol. Lett., 144, 197 202 (1996).
. N Noguchi, A Emura, M Sasatsu, M Kono, Biol. Pharm. Bull. 17Noguchi N., Emura A., Sasatsu M., Kono M., Biol. Pharm. Bull., 17, 352 355 (1994).
. A Yamaguchi, Y Shiina, E Fujihira, T Sawai, N Noguchi, M Sasatsu, FEBS Lett. 365Yamaguchi A., Shiina Y., Fujihira E., Sawai T., Noguchi N., Sasatsu M., FEBS Lett., 365, 193 197 (1995).
. M Kono, N Noguchi, M Sasatsu, Agric, Biol. Chem. 47Kono M., Noguchi N., Sasatsu M., Agric. Biol. Chem., 47, 2393 2394 (1983).
. M Kono, M Sasatsu, T Aoki, N Noguchi, Agric, Biol. Chem. 48Kono M., Sasatsu M., Aoki T., Noguchi N., Agric. Biol. Chem., 48, 821 822 (1984).
. N Noguchi, J Katayama, Biol. Pharm. Bull. 21Noguchi N., Katayama J., Biol. Pharm. Bull., 21, 191 193 (1998).
. P S Lovett, N P AmbulosJr, W Mulbry, N Noguchi, E J Rogers, J. Bacteriol. 173Lovett P. S., Ambulos N. P. Jr., Mulbry W., Noguchi N., Rogers E. J., J. Bacteriol., 173, 1810 1812 (1991).
. A Taguchi, K Hamada, M Kotake, M Shiozuka, H Nakaminami, T Pillaiyar, K Takayama, F Yakushiji, N Noguchi, T Usui, R Matsuda, Y Hayashi, ChemMedChem. 9Taguchi A., Hamada K., Kotake M., Shiozu- ka M., Nakaminami H., Pillaiyar T., Takaya- ma K., Yakushiji F., Noguchi N., Usui T., Matsuda R., Hayashi Y., ChemMedChem, 9, 2233 2237 (2014).
. M Kono, K Ohmiya, T Kanda, N Noguchi, K O'hara, FEMS Microbiol. Lett. 40Kono M., Ohmiya K., Kanda T., Noguchi N., O'Hara K., FEMS Microbiol. Lett., 40, 223 228 (1987).
. K Ohmiya, T Tanaka, N Noguchi, K O'hara, M Kono, Gene. 78Ohmiya K., Tanaka T., Noguchi N., O'Hara K., Kono M., Gene, 78, 377 378 (1989).
. M Sasatsu, Y Shibata, N Noguchi, M Kono, FEMS Microbiol. Lett. 72Sasatsu M., Shibata Y., Noguchi N., Kono M., FEMS Microbiol. Lett., 72, 109 113 (1992).
. N Noguchi, M Hase, M Kitta, M Sasatsu, K Deguchi, M Kono, FEMS Microbiol. Lett. 172Noguchi N., Hase M., Kitta M., Sasatsu M., Deguchi K., Kono M., FEMS Microbiol. Lett., 172, 247 253 (1999).
. N Noguchi, M Tamura, K Narui, K Wakasugi, M Sasatsu, Biol. Pharm. Bull. 25Noguchi N., Tamura M., Narui K., Wakasugi K., Sasatsu M., Biol. Pharm. Bull., 25, 1129 1132 (2002).
. N Noguchi, H Okada, K Narui, M Sasatsu, Microb. Drug Resist. 10Noguchi N., Okada H., Narui K., Sasatsu M., Microb. Drug Resist., 10, 197 203 (2004).
. N Noguchi, J Suwa, K Narui, M Sasatsu, T Ito, K Hiramatsu, J H Song, J. Med. Microbiol. 54Noguchi N., Suwa J., Narui K., Sasatsu M., Ito T., Hiramatsu K., Song J. H., J. Med. Microbiol., 54, 557 565 (2005).
. K Narui, N Noguchi, M Sasatsu, . J Jpn, Pharm, Health Care Sci. 29Narui K., Noguchi N., Sasatsu M., Jpn. J. Pharm. Health Care Sci., 29, 279 286 (2003).
. K Narui, M Takano, N Noguchi, M Sasatsu, Biol. Pharm. Bull. 30Narui K., Takano M., Noguchi N., Sasatsu M., Biol. Pharm. Bull., 30, 585 587 (2007).
. H Nakaminami, N Noguchi, M Sasatsu, Antimicrob. Agents Chemother. 54Nakaminami H., Noguchi N., Sasatsu M., Antimicrob. Agents Chemother., 54, 4107 4111 (2010).
L T Paulsen, M H Brown, T G Littlejohn, B A Mitchell, R A Skurry, Proc. Natl. Acad. Sci. Natl. Acad. SciUSA, 93Paulsen L. T., Brown M. H., Littlejohn T. G., Mitchell B. A., Skurry R. A., Proc. Natl. Acad. Sci. USA, 93, 3630 3635 (1996).
. E Miyajima, D Harada, H Nakaminami, Y Kitamura, T Tamura, T Kawakubo, N Noguchi, Microb. Drug Resist. 25Miyajima E., Harada D., Nakaminami H., Kitamura Y., Tamura T., Kawakubo T., Noguchi N., Microb. Drug Resist., 25, 1032 1040 (2019).
. S Horikawa, N Tadasa, K Narui, N Noguchi, M Sasatsu, . J Jpn, Pharm, Health Care Sci. 34Horikawa S., Tadasa N., Narui K., Noguchi N., Sasatsu M., Jpn. J. Pharm. Health Care Sci., 34, 1017 1022 (2008).
. K Narui, N Noguchi, N Matsunaga, Y Namiki, Y Yamanaka, Y Kumaki, J Suwa, Y Nasu, M Koyama, K Okuyama, K Utsumi, K Takazawa, K Wakasugi, M Sasatsu, J , Hosp. Infect. 73Narui K., Noguchi N., Matsunaga N., Namiki Y., Yamanaka Y., Kumaki Y., Suwa J., Nasu Y., Koyama M., Okuyama K., Utsumi K., Takazawa K., Wakasugi K., Sasatsu M., J. Hosp. Infect., 73, 24 33 (2009).
. K Watanabe, H Nakaminami, C Azuma, I Tanaka, K Nakase, N Matsunaga, K Okuyama, K Yamada, K Utsumi, T Fujii, N Noguchi, Biol. Pharm. Bull. 39Watanabe K., Nakaminami H., Azuma C., Tanaka I., Nakase K., Matsunaga N., Okuya- ma K., Yamada K., Utsumi K., Fujii T., Noguchi N., Biol. Pharm. Bull., 39, 1868 1875 (2016).
. H Miyamatsu, Y Kanno, Y Sekine, H Kobayashi, T Hasegawa, M Koyano, M Hashimoto, N Noguchi, M Sasatsu, M Abe, T Akashi, Jpn. J. Pharm. Health Care Sci. 33Miyamatsu H., Kanno Y., Sekine Y., Kobayashi H., Hasegawa T., Koyano M., Hashimoto M., Noguchi N., Sasatsu M., Abe M., Akashi T., Jpn. J. Pharm. Health Care Sci., 33, 30 35 (2007).
. K Watanabe, M Shioura, H Nakaminami, M Sasatsu, N Noguchi, Jpn, J. Pharm. Health Care Sci. 39Watanabe K., Shioura M., Nakaminami H., Sasatsu M., Noguchi N., Jpn. J. Pharm. Health Care Sci., 39, 304 308 (2013).
. I Tanaka, K Watanabe, H Nakaminami, C Azuma, N Noguchi, Yakugaku Zasshi, 134Tanaka I., Watanabe K., Nakaminami H., Azuma C., Noguchi N., Yakugaku Zasshi, 134, 1219 1225 (2014).
. N Noguchi, T Ohashi, T Shiratori, K Narui, T Hagiwara, M Ko, K Watanabe, T Miyahara, S Taira, F Moriyasu, M Sasatsu, J. Gastroenterol. 42Noguchi N., Ohashi T., Shiratori T., Narui K., Hagiwara T., Ko M., Watanabe K., Miya- hara T., Taira S., Moriyasu F., Sasatsu M., J. Gastroenterol., 42, 346 351 (2007).
. N Noguchi, M Fukuzawa, T Wajima, K Yokose, M Suzuki, H Nakaminami, Noguchi N., Fukuzawa M., Wajima T., Yokose K., Suzuki M., Nakaminami H.,
. T Kawai, F Moriyasu, M Sasatsu, J. Infect. Public Health. 11Kawai T., Moriyasu F., Sasatsu M., J. Infect. Public Health, 11, 39 42 (2018).
. N Noguchi, H Nakaminami, S Nishijima, I Kurokawa, H So, M Sasatsu, J. Clin. Microbiol. 44Noguchi N., Nakaminami H., Nishijima S., Kurokawa I., So H., Sasatsu M., J. Clin. Microbiol., 44, 2119 2125 (2006).
. S Takadama, H Nakaminami, S Aoki, M Akashi, T Wajima, M Ikeda, A Mochida, F Shimoe, K Kimura, Y Matsuzaki, D Sawamura, Y Inaba, T Oishi, O Nemoto, N Baba, N Noguchi, J. Infect. Chemother. 23Takadama S., Nakaminami H., Aoki S., Akashi M., Wajima T., Ikeda M., Mochida A., Shimoe F., Kimura K., Matsuzaki Y., Sawamura D., Inaba Y., Oishi T., Nemoto O., Baba N., Noguchi N., J. Infect. Chemother., 23, 800 803 (2017).
. A Ito, H Nakaminami, T Fujii, K Utsumi, N Noguchi, J. Med. Microbiol. 64Ito A., Nakaminami H., Fujii T., Utsumi K., Noguchi N., J. Med. Microbiol., 64, 745 751 (2015).
. D Harada, H Nakaminami, E Miyajima, T Sugiyama, N Sasai, Y Kitamura, T Tamura, T Kawakubo, N Noguchi, J. Infect. Chemother. 24Harada D., Nakaminami H., Miyajima E., Sugiyama T., Sasai N., Kitamura Y., Tamura T., Kawakubo T., Noguchi N., J. Infect. Chemother., 24, 563 569 (2018).
. H Nakaminami, S Takadama, A Ito, M Hasegawa, C Jono, M Noguchi, M Shoshi, T Wajima, T Fujii, H Maruyama, H Sakamoto, Y Ito, S Okamoto, Y Masaki, K Tsuchiya, S Nishinarita, N Noguchi, J. Med. Microbiol. 67Nakaminami H., Takadama S., Ito A., Hasegawa M., Jono C., Noguchi M., Shoshi M., Wajima T., Fujii T., Maruyama H., Sakamoto H., Ito Y., Okamoto S., Masaki Y., Tsuchiya K., Nishinarita S., Noguchi N., J. Med. Microbiol., 67, 769 774 (2018).
. S Takadama, H Nakaminami, A Sato, M Shoshi, T Fujii, N Noguchi, Clin. Microbiol. Infect. 247Takadama S., Nakaminami H., Sato A., Shoshi M., Fujii T., Noguchi N., Clin. Microbiol. Infect., 24, 1211.e1 1211.e7 (2018).
. S Takadama, H Nakaminami, T Takii, N Noguchi, Diagn. Microbiol. Infect. Dis. 94Takadama S., Nakaminami H., Takii T., Noguchi N., Diagn. Microbiol. Infect. Dis., 94, 86 87 (2019).
. S Takadama, Y Yamagishi, H Nakaminami, T Morishima, M Deie, H Mikamo, N Noguchi, J. Infect. Chemother. 25Takadama S., Yamagishi Y., Nakaminami H., Morishima T., Deie M., Mikamo H., Noguchi N., J. Infect. Chemother., 25, 212 214 (2019).
. S Takadama, H Nakaminami, H Kaneko, N Noguchi, J. Antimicrob. Chemother. 75Takadama S., Nakaminami H., Kaneko H., Noguchi N., J. Antimicrob. Chemother., 75, 3131 3134 (2020).
. T Kobayashi, H Nakaminami, H Ohtani, K Yamada, Y Nasu, S Takadama, N Noguchi, T Fujii, T Matsumoto, J. Infect. Chemother. 26Kobayashi T., Nakaminami H., Ohtani H., Yamada K., Nasu Y., Takadama S., Noguchi N., Fujii T., Matsumoto T., J. Infect. Chemother., 26, 76 81 (2020).
. R Yokomori, J Tsurukiri, M Moriya, H Yamanaka, T Kobayashi, H Nakaminami, S Takadama, N Noguchi, T Matsumoto, T Arai, J Jma, 3Yokomori R., Tsurukiri J., Moriya M., Yamanaka H., Kobayashi T., Nakaminami H., Takadama S., Noguchi N., Matsumoto T., Arai T., JMA J., 3, 78 82 (2020).
. M Moriya, J Tsurukiri, H Nakaminami, H Yamanaka, T Kobayashi, N Tsubouchi, R Yokomori, S Takadama, N Noguchi, T Matsumoto, T Arai, J. Infect. Moriya M., Tsurukiri J., Nakaminami H., Yamanaka H., Kobayashi T., Tsubouchi N., Yokomori R., Takadama S., Noguchi N., Matsumoto T., Arai T., J. Infect.
. Chemother, 26Chemother., 26, 862 864 (2020).
. N Hayashi, H Akamatsu, K Iwatsuke, R Ohmori, C Uenaka, I Kurokawa, K Kono, M Kobayashi, M Tanioka, F Furukawa, M Komura, O Yamazaki, T Yamazaki, Y Yamamoto, Y Miyaji, M Kawashima, Jpn, J. Dermatol. 126Hayashi N., Akamatsu H., Iwatsuke K., Ohmori R., Uenaka C., Kurokawa I., Kono K., Kobayashi M., Tanioka M., Furukawa F., Komura M., Yamazaki O., Yamazaki T., Yamamoto Y., Miyaji Y., Kawashima M., Jpn. J. Dermatol., 126, 1261 1302 (2017).
. K Nakase, N Hayashi, Y Akiyama, S Aoki, N Noguchi, J. Dermatol. 44Nakase K., Hayashi N., Akiyama Y., Aoki S., Noguchi N., J. Dermatol., 44, 1248 1254 (2017).
. K Nakase, H Nakaminami, Y Takenaka, N Hayashi, M Kawashima, N Noguchi, J. Med. Microbiol. 63Nakase K., Nakaminami H., Takenaka Y., Hayashi N., Kawashima M., Noguchi N., J. Med. Microbiol., 63, 721 728 (2014).
. K Nakase, S Aoki, S Sei, S Fukumoto, Y Horiuchi, T Yasuda, M Tanioka, J Sugai, W.-K W Huh, M Kakuta, M Nomoto, T Shimada, M Watanabe, M Kobayashi, S Murakami, C Takeo, R Tsubouchi, N Hayashi, N Noguchi, J. Dermatol. 47Nakase K., Aoki S., Sei S., Fukumoto S., Horiuchi Y., Yasuda T., Tanioka M., Sugai J., Huh W.-K. W., Kakuta M., Nomoto M., Shimada T., Watanabe M., Kobayashi M., Murakami S., Takeo C., Tsubouchi R., Hayashi N., Noguchi N., J. Dermatol., 47, 863 869 (2020).
. S Aoki, K Nakase, H Nakaminami, T Wajima, N Hayashi, N Noguchi, Anitimicrob. Agents Chemoter. 64Aoki S., Nakase K., Nakaminami H., Wajima T., Hayashi N., Noguchi N., Anitimicrob. Agents Chemoter., 64, e01810-19 (2020).
. T Wajima, Y Anzai, T Yamada, H Ikoshi, N Noguchi, PLoS One. 11167335Wajima T., Anzai Y., Yamada T., Ikoshi H., Noguchi N., PLoS One, 11, e0167335 (2016).
. T Yamada, T Wajima, H Nakaminami, K Kobayashi, H Ikoshi, N Noguchi, BMC Complement. Altern. Med. 16463Yamada T., Wajima T., Nakaminami H., Kobayashi K., Ikoshi H., Noguchi N., BMC Complement. Altern. Med., 16, 463 (2016).
. Y Maezawa, H Nakaminami, S Takadama, M Hayashi, T Wajima, K Nakase, T Yamada, H Ikoshi, N Noguchi, PLoS One. 14214470Maezawa Y., Nakaminami H., Takadama S., Hayashi M., Wajima T., Nakase K., Yamada T., Ikoshi H., Noguchi N., PLoS One, 14, e0214470 (2019).
. K Nakase, A Tashiro, T Yamada, H Ikoshi, N Noguchi, J. Dermatol. 46Nakase K., Tashiro A., Yamada T., Ikoshi H., Noguchi N., J. Dermatol., 46, 308 313 (2019).
. T Wajima, R Kinugawa, T Yamada, H Ikoshi, N Noguchi, Pharmacology. 103Wajima T., Kinugawa R., Yamada T., Ikoshi H., Noguchi N., Pharmacology, 103, 221 227 (2019).
| [
-0.17396141588687897,
-0.16101810336112976,
-0.09843361377716064,
-0.036347512155771255,
-0.014363802969455719,
0.10089569538831711,
-0.3145325183868408,
0.24915026128292084,
0.19017069041728973,
0.07826443016529083,
0.007604706101119518,
-0.14816707372665405,
0.19645115733146667,
0.247444... |
Impurities or a neutral Fermi surface? A further examination of the low-energy ac optical conductivity of SmB 6
N J Laurita
Department of Physics and Astronomy
The Institute For Quantum Matter
The Johns Hopkins University
21218BaltimoreMarylandUSA
C M Morris
Department of Physics and Astronomy
The Institute For Quantum Matter
The Johns Hopkins University
21218BaltimoreMarylandUSA
S M Koohpayeh
Department of Physics and Astronomy
The Institute For Quantum Matter
The Johns Hopkins University
21218BaltimoreMarylandUSA
W A Phelan
Department of Physics and Astronomy
The Institute For Quantum Matter
The Johns Hopkins University
21218BaltimoreMarylandUSA
Department of Chemistry
The Johns Hopkins University
21218BaltimoreMarylandUSA
T M Mcqueen
Department of Physics and Astronomy
The Institute For Quantum Matter
The Johns Hopkins University
21218BaltimoreMarylandUSA
Department of Chemistry
The Johns Hopkins University
21218BaltimoreMarylandUSA
Department of Materials Science and Engineering
The Johns Hopkins University
21218BaltimoreMarylandUSA
N P Armitage
Department of Physics and Astronomy
The Institute For Quantum Matter
The Johns Hopkins University
21218BaltimoreMarylandUSA
Impurities or a neutral Fermi surface? A further examination of the low-energy ac optical conductivity of SmB 6
Kondo InsulatorsTime-domain terahertz spectroscopyoptical conductivity PACS: 7820Ci7127+a7128+d
Recent experiments have uncovered evidence of low energy excitations in the bulk of SmB6 that are perhaps associated with unconventional quasiparticles, bringing into question whether this Kondo "insulator" is truly insulating in the bulk. Recently, we demonstrated that SmB6 possesses significant in-gap bulk ac conduction far in excess of typical disordered semiconductors. Whether such conduction is an intrinsic feature of SmB6, suggesting the formation of an exotic state, or residual conduction from impurities continues to be a topic of debate. Here, we further examine the origin of the ac optical conductivity of SmB6 in light of recent experimental and theoretical developments. The optical conductivity of SmB6 is shown to possess distinct regimes of either dominant free carrier or localized response contributions. The free carrier response is found to be in good qualitative agreement with previous literature, although quantitative differences are revealed and discussed. The localized response, which dominates at the lowest temperatures, is analyzed in the context of models of either in-gap impurity states or an exotic neutral Fermi surface. The charge density or effective mass of this low temperature in-gap conductivity is extracted through a conductivity sum rule analysis and found to be in general alignment with both models in the appropriate limits. Our results shed further light on the nature of the in-gap states of this remarkable material.
Introduction
Gapped systems are hallmarked by an exponential divergence of their resistivity with reducing temperature. Deviations from this behavior are indicative of additional conduction mechanisms, whether they be extrinsic, perhaps stemming from impurities or disorder, or intrinsic, for instance resulting from the formation of topological surface states. In the late 1960's, resistivity measurements [1,2] performed on the mixed-valent [3] semiconductor SmB 6 revealed two prominent features: First, the onset of such an exponential dependence at T ≈ 50K, signifying a crossover from metallic to insulating behavior. Today this crossover is known to stem from the hybridization of localized 4f electrons near the Fermi level and itinerant 5d electrons [4,5,3], opening a gap in the density of states of order ∆ g ≈ 20 meV. The second, and more surprising, feature is a plateauing of the resistivity that occurs at temperatures T < 5K, signifying a new dominant conduction mechanism. Despite intense experimental and theoretical investigation, the physics behind this plateau has remained a mystery for nearly half a century.
Interest in SmB 6 was rekindled in 2010 due to the seminal prediction that SmB 6 may be the first known example of a topological Kondo insulator (TKI), a new state of matter in which strong interactions and spin-orbit coupling conspire to open a parity inverted gap with corresponding in-gap topological surface states [6]. In this interpretation, the plateau in the resistivity of SmB 6 results from the topological surface states which short out the insulating bulk at low temperatures. Accordingly, a flurry of theoretical [6][7][8][9][10] and experimental [11][12][13][14][15][16][17][18][19][20][21][22][23] investigations into the physical properties of SmB 6 have been reported in recent years, many of which have proclaimed findings consistent, although perhaps not conclusively so, with the TKI prediction.
The realization of a TKI is certainly an exciting prospect. It has been proposed that since the gap of SmB 6 is interaction driven it may be truly insulating, which has generally not been the case in other classes of non-interacting topological insulators. Therefore, SmB 6 may be better suited for technological applications. Indeed, dc resistivity measurements do suggest an insulating bulk [11][12][13][14] with more recent measurements observing the exponential divergence of the bulk resistivity over an incredible 10 orders of magnitude, including to very low temperatures deep within the plateaued regime [24].
However, the story of SmB 6 took an unexpected turn in 2015 when torque magnetometry experiments performed by Tan et al. [25] uncovered what appeared to be quantum oscillations associated with an unconventional 3dimensional Fermi surface, potentially consisting of exotic neutral quasiparticles. In fact, evidence of a potentially exotic state within the bulk of SmB 6 can be traced back decades. It has long been known that the Sommerfeld coefficient of the specific heat of SmB 6 is unusually large, γ ≈ 10 mJ/mol*K 2 [26-28] -10 times larger than metallic LaB 6 . Such large fermionic specific heat has since been shown to be a bulk effect [29]. Additionally, low-energy ac conductivity experiments of SmB 6 have revealed in-gap conduction consistent with a localized response with conductivities orders of magnitude larger than the dc value [30][31][32][33][34][35]. The aforementioned experimental findings raise an important red flag in our understanding of SmB 6 ; is the Kondo insulator SmB 6 even...an insulator?
We raised this question in a previous publication based on our low-energy optical spectroscopy experiments [36]. In that work we definitively demonstrated that the large ingap ac conduction of SmB 6 is three-dimensional and therefore a bulk effect. Whether such large in-gap conduction is a hint of an exotic state [37][38][39] or simply residual conduction from impurities [40][41][42][43][44] continues to be a topic of debate. However, we argued that there are reasons to believe that such conduction may be intrinsic to SmB 6 . For instance, we found that the ac conductivity was highly repeatable, even when comparing samples grown by different techniques -in stark contrast to the exponentially sensitive conduction of impurity band insulators [45]. Furthermore, although the in-gap conductivity displays a power law frequency dependence that resembles impurity band insulators, it is orders of magnitude larger than what is observed in disordered semiconductors and is more on-par with completely amorphous alloys [46].
In this work, we further analyze the optical conductivity of SmB 6 in the context of recent theoretical and experimental developments. As our experimental energy range, 1 -8 meV, is less than the bulk gap, ∆ g ≈ 20 meV, we directly probe the in-gap conduction of SmB 6 . The conductivity is modeled with two contributions -a free carrier response which dominates at high temperatures and a "localized" response which dominates within the plateaued state. To be clear, the term localized does not necessarily refer to the charge carriers themselves, but to the response of the current as it is inferred that the dc conductivity goes to zero in the zero frequency limit. The free carrier response is found to be in good qualitative agreement with previous literature, although quantitative differences are revealed and discussed. The localized response is analyzed in the context of models of either in-gap impurity states or an exotic neutral Fermi surface. The charge density or effective mass of this low temperature in-gap conductivity is extracted through a conductivity sum rule analysis and found to be in general alignment with both models in the appropriate limits. Our results shed further light on the nature of the in-gap states of this remarkable material.
Methods
Highly sensitive time-domain terahertz (TDTS) experiments were performed on single crystal samples of SmB 6 grown by both optical floating zone and aluminum flux growth techniques. In the present paper, we concentrate solely on samples grown by the optical floating zone method. Such optical transmission experiments are exceptionally difficult to perform on SmB 6 due to the material's high index of refraction (n ≈ 25) and, as demonstrated below, large absorption in the THz range. Correspondingly, novel methods for performing TDTS experiments on SmB 6 were developed. Details of our methods, which involved mounting SmB 6 samples to Al 2 O 3 substrates and polishing to thicknesses of 10's of µm, can be found in Ref. [36].
TDTS transmission experiments were performed using a home built spectrometer within a temperature range of 1.6K to 300K [47] on single crystal SmB 6 samples oriented such that theĉ [001] axis was perpendicular to the plane of the sample surface. TDTS is a high resolution method for accurately measuring the electromagnetic response of a sample in the experimentally challenging THz range. In our TDTS experiments, the electric field of a transmitted THz pulse through a SmB 6 sample mounted to an Al 2 O 3 substrate was measured as a function of real time. Performing a Fourier transform of the measured time-domain electric field and referencing to the transmitted electric field through an identical substrate allows access to the frequency dependent complex transmission spectrum of the sample. The complex transmission is then given by:
T (ω) = 2 n( n s + 1) ( n + 1)( n + n s ) exp [ iωd c ( n − 1)](1)
where d is the sample thickness, ω is the frequency, c is the speed of light, n is the sample's complex index of refraction, n s = 3.1 is the Al 2 O 3 substrate's index of refraction, and normal incidence in a vacuum has been assumed. The complex transmission can then be numerically inverted via a Newton-Raphson algorithm to obtain the sample's complex index of refraction from which the complex optical conductivity can be determined. Fig. 1(a) displays the magnitude of the complex transmission, as defined in Eq. 1, as a function of temperature and frequency for a representative sample grown by the optical floating zone method with thickness d = 22 µm. Samples grown by the aluminum flux method display similar results but with poorer signal to noise due to smaller sample sizes and technical aspects of our measurement [36]. Therefore, we focus here on the optical floating zone samples. At the lowest temperatures, the largest transmission of ≈ 20% is observed and then quickly decreases with increasing frequency. The transmission also displays strong temperature dependence, decreasing with increasing temperature until becoming opaque in the THz range for temperatures T ≥ 30K for sample thicknesses d > 10 µm. As we will discuss below these features are generally consistent with residual conductivity within a gap which is closing or filling in with increasing temperature.
Experimental Results
Optical Conductivity Of SmB 6
As stated in the methods section above, the real and imaginary parts of the complex optical conductivity can be extracted from the complex transmission via numerical inversion of Eq. 1. Fig. 1(b) displays the real part of the optical conductivity, σ 1 (ω, T ), which was extracted from the transmission shown in Fig. 1(a). With some notable differences discussed previously [36], the general frequency and temperature dependence of these data are in rough agreement with those of previously reported optical studies of SmB 6 [31,[33][34][35], although the exceptionally high resolution of our measurements provides new details.
The conductivity displays a crossover from metallic to insulating behavior as a function of temperature. At the highest measured temperatures a Drude-like response is observed as the optical conductivity is largest at the lowest frequencies and is a decreasing function of frequency thereafter. The Drude-like response indicates the presence of free charge carriers in the conduction band. As the temperature is reduced, the magnitude of the Drude response correspondingly decreases, disappearing at T ≈ 13K, at which point the conductivity is nearly frequency independent out to 2 THz. At lower temperatures, T < 13K, the conductivity becomes an increasing function of frequency, displaying approximately linear behavior below ≈ 1 THz. This change in the functional dependence of the conductivity with frequency signifies a shift to a new dominant conduction mechanism consistent with a localized response within the gap. Above 1 THz the conductivity saturates and displays little dependence with temperature or frequency.
It is clear from the discussion above that the conductivity of SmB 6 in the THz range consists of at least two contributions, a Drude-like response from free charge carriers and additional conduction from the "localized" response. As mentioned above, we refer here to the non-Drude conductivity as being associated with a localized response as these states do not contribute to the dc transport. However, if a neutral Fermi surface does exists within the gap of SmB 6 then the excitations themselves may be delocalized. Thus "localized" is simply terminology.
Here we make the ansatz that the conductivity of the localized response is independent of temperature in our measurement range. This assumption is supported by the weak temperature dependence of the conductivity at high frequencies, well above the scattering rate of the Drude contribution. We can then model the total frequency and temperature dependent conductivity as:
σ 1,Tot (ω, T ) = σ 1,Loc (ω) + σ 1,Drude (ω, T ) + σ 1,min (T ) (2)
where σ 1,Drude (ω, T ) is the free carrier response, σ Loc (ω) is the temperature independent conductivity of the localized response, and σ min (T ) is a frequency independent background conductivity which was found to be required to accurately fit the spectra above 12K. It should be noted that
f 2 pl ∝ exp (−∆ 1 /k B T ) while the red dashed line corresponds to a fit with f 2 pl ∝ exp (−∆ 2 /2k B T )
such that a direct comparison to Ref [35] can be made.
this minimum conductivity has been previously included in fits of the optical conductivity of SmB 6 [35], and interpreted in terms of a Mott minimum conductivity [48]. With the conductivity modeled in this fashion, we can now separate the free carrier and localized responses and analyze them independently.
Analysis Of The Free Carrier Response
To isolate the free carrier response, we simply subtract the conductivity of the localized response from the total conductivity shown in Figure 1(b). We can identify the localized conductivity to be the total conductivity at the lowest measured temperature, T = 1.6K, at which point the free carrier conductivity is frozen out. Subtracting the conductivity at T = 1.6K then isolates the free carrier response apart from the background σ 1,min (T ), which can be included in a fit and subtracted as well. Figure 2(a) displays the extracted free carrier conductivity (dashed lines) found by subtracting the 1.6K conductivity and σ 1,min as described above. As expected, the free carrier conductivity is largest at high temperatures and low frequencies. As the temperature is reduced, thermal activation across the gap is frozen out and the corresponding free carrier conduction is significantly reduced.
We can model the free carrier conductivity with the Drude model, in which case the frequency dependent ac conductivity is given by:
σ 1,Drude (ω) = σ dc γ 2 (γ 2 + ω 2 )(3)
where σ dc = ne 2 τ /m * = f 2 pl /2γ is the dc conductivity, γ = 1/2πτ is the scattering rate, f pl is the plasma frequency and n and m * are the charge density and effective mass respectively. Solid lines in Figure 2(a) are fits of the spectra to Eq. 3. One can see that the free carrier conductivity is well described by the Drude model, consistent with our overall conductivity model given in Eq. 2.
We can then extract the temperature dependent dynamical properties of the free charge carriers from the Drude fits shown in Figure 2(a). Figure 2(b) displays the temperature dependence of the extracted dc conductivity, which displays the expected activated behavior with temperature. We can ascertain the activated energy scale by fitting the dc conductivity with the expression σ dc ∝ exp (−∆/k B T ) where ∆ is the activation energy. The red dashed line in Figure 2(b) displays a fit of the dc conductivity with such an activated exponential. Only data above 7K were used for the fit as the conductivity is most Drude-like in this temperature range. From these fits we extract an energy scale of ∆ = 4.14 meV, in excellent agreement with previous dc resistivity measurements [1,2,[11][12][13][14] and the ∆ = 4.01 meV found in recent Corbino measurements, which have measured the bulk resistivity over 10 orders of magnitude [24]. Also shown in Figure 2(b) is the temperature dependence of the minimum conductivity σ 1,min (T ), which is only finite above 12K, reaching a maximum value of 9.4 Ω −1 cm −1 at 17.5K.
The inset of Figure 2(b) displays the scattering rate as a function of temperature. The scattering rate is difficult to extract at low temperatures as the Drude conductivity quickly diminishes in magnitude. However, the general trend of a slightly increasing scattering rate as the temperature is reduced is observed in the data down to 7K. Below this temperature the error bars are too large to definitively assess the temperature dependence of the scattering rate and therefore this data is not included in the inset. Figure 2(c) displays an Arrhenius plot the square of the plasma frequency, a quantity proportional to n/m * . Much like the dc conductivity, one expects f 2 pl to possess activated behavior due to the temperature dependence of the charge density, although the implicit assumption here is that the effective mass is temperature independent over the temperature range of our measurement. Fitting these data to similar activated expressions as the dc conductivity reveals two distinct regimes of activated temperature dependence with different energy gaps separated by an inflection point at 10 K. Below 10K we find an activation gap of ∆ 1 = 1.42 meV while above 10K we find an activation gap of ∆ 2 = 5.63 meV. These findings will be addressed in the discussion below.
Analysis Of The Localized Response
We identified the conductivity at the lowest measured temperature, 1.6K, to be the local response within the gap, as the Drude response is frozen out at these temperatures. It was assumed that this conductivity is temperature independent at least up to 20K, as evidenced by the weak temperature dependence of the conductivity at high frequencies. Here we analyze the conductivity of the localized response in more depth. Figure 3(a) displays the localized conductivity as a function of frequency at T = 1.6K. The conductivity can be separated into two regimes. Below 1 THz, we find the conductivity is well described by a power law expression, σ 1,loc (ω) ∝ ω n with an exponent n ≈ 0.8. Above 1 THz the conductivity shifts to a linear dependence with frequency, although fitting the conductivity over such a small frequency range is likely not definitive. It should be noted that the energy scale of this crossover with frequency, ≈ 4 meV, is identical to the bulk activated energy scale observed in dc transport experiments. We return to this observation in the discussion below.
We discussed the frequency dependence of this localized conductivity in some detail previously [36]. If such conduction stems entirely from impurity states then one might draw a parallel between SmB 6 and models of disordered Kondo insulators, which have investigated the effects of substitutional doping of the f -ion sites [41,43,49,50]. These models suggest that the Kondo gap is exceptionally sensitive to impurities as they break the translational invariance of the Kondo lattice and therefore destroy of the coherence of the heavy-fermion ground state. For small impurity concentrations, these models predict an impurity band to form within the gap which scales with the square root of the impurity concentration. At a critical impurity concentration, suggested to be as little as a 1%, a percolation threshold between impurity states is reached, effectively closing the bulk gap. The expected optical conductivity of these models depends on whether the impurity concentration is above or below this threshold. Above the percolation threshold, the conductivity is expected to be a weak Drude peak for frequencies below the indirect gap, which is inconsistent with our observation of power law conductivity at low frequencies in SmB 6 . However, the conductivity below the percolation threshold, when the impurity states are presumably localized, has not yet been investigated to best of our knowledge.
For a comparison to localized impurity states in disordered semiconductors, one may turn to localization driven insulators such as the disordered "electron glass" Si:P [45]. In such insulators, the expectation is that at the lowest temperatures ac conduction occurs between resonant pairs of localized states. Without interactions the ac conductivity is expected to follow Mott's famous ω 2 law [51], which is clearly inconsistent with the data exhibited here. With interactions included, but at frequency scales below that of the characteristic interaction energy between electronhole pairs, the expectation is that the conductivity is quasilinear with σ 1 (ω) = e 4 D( F ) 2 ξ 4 [ln(2I 0 / ω)] 3 ω/ where ξ is the localization length, D( F ) is the density of states at the Fermi level, and I 0 is the characteristic scale of tunneling between localized states that is expected to be bounded by the hybridization gap energy [52]. Our ac conductivity data shown in Figure 3(a) is roughly consistent with this model below 1 THz, with the caveat that the power law exponent is n ≈ 0.8 instead of the expected linear dependence. However the ω 2 dependence, expected at frequencies above the interaction energy scale of the system, is never recovered up to 2 THz.
However, whatever partial qualitative agreement exists between these data and that of localization driven insulators is overshadowed by the stark quantitative differences. The in-gap ac conductivity of SmB 6 is ≈ 4 orders of magnitude larger than the impurity band conduction in Si:P (at say doped 39% of the way towards the 3D metal-insulator transition) [45] and is essentially of the scale of the ac conduction in completely amorphous Nb x Si 1−x alloys [46]. Therefore, one must consider other possibilities. Recent theories have proposed mechanisms by which one might attain a charge neutral Fermi surface within the Kondo gap [53,[37][38][39]. Such neutral quasiparticles would be inert in dc transport experiments but may still couple to ac fields [54]. A separate theory claims that these in-gap localized states may originate from intrinsic electrons in SmB 6 that become self trapped through interactions with valence fluctuations [55]. Such theories have predicted functional forms for the optical conductivity in the context of their models but thus far none have predicted a power law behavior at low frequencies with exponents of n ≈ 1, as is observed in our measurements.
We can further characterize the origin of the localized carrier conduction by examining the spectral weight of the in-gap conductivity. In an optics measurement, the spectral weight of a band can be related to the density of charge carriers n and effective mass m * through the conductivity sum rule relation:
W 0 σ 1 (ω) dω = ne 2 πm *(4)
where the upper limit of the integral is the unrenormalized electronic bandwidth [56,57]. Figure 3(b) displays the localized conductivity with extrapolations of our fits of the data from zero frequency to 20 meV, roughly the expected value of the hybridization gap edge where it is known the conductivity rises by several orders of magnitude [35]. The gray shaded area represents an estimate of the spectral weight of this band. Using this area we may then make an estimate for the charge density of the localized response, although performing such an analysis requires knowledge of the effective mass. Given the already crude nature of this approximation we assume that the effective mass is simply the free electron mass, although further discussion on this point will be made below. Performing the calculation as described results in an extracted charge density of n = 1.75 × 10 19 cm −3 or ≈ 1 electron / 1000 unit cells. This charge density will be analyzed in the context of impurities or a potentially exotic state in the discussion below.
Discussion
The analysis presented in this work is similar to that of a previous infrared conductivity study of SmB 6 [35], which also separated the optical conductivity into free carrier and localized responses. While aspects of the data presented here are in agreement with Ref. [35], important differences exist, particularly in regards to the localized response. Here we discuss how our results compare to previous studies and how our interpretations differ given recent developments in the understanding of SmB 6 .
Our analysis of the free carrier response is in good qualitative agreement with the results of Ref. [35], although quantitative differences exist. For instance, the scattering rate reported in Ref. [35] is significantly smaller than that found in this work. Gorshunov et al. report a scattering rate of γ ≈ 90 GHz below 15K, only roughly 20% the γ ≈ 0.5 THz observed here. Additional differences are found in the temperature dependence of the scattering rate. Gorshunov et al. report a temperature independent scattering rate below 15K which was attributed to dominant impurity scattering. Our extracted scattering rate displays a weak increasing behavior with reducing temperature from 20K to 6K. It is unclear where this discrepancy originates. It is possible that such an increase may be caused by slight temperature dependence of the localized conductivity, which we have assumed to be temperature independent in our model. However, the validity of our model is evidenced by the fact that the extracted dc conductivity agrees with dc transport measurements performed on a sample from the same batch and displays the expected activated behavior with an energy scale in excellent agreement with dc transport experiments.
Additional distinctions are found in the temperature dependence of the plasma frequency. Both our work and Ref. [35] find the plasma frequency to display two distinct temperature regions of activated behavior with different activation energies. However, the activated energies extracted in these two regimes are fairly different between our measurements. Gorshunov et al. report activation energies of 19 meV and 3 meV above and below 15K respectively, while our measurements indicate activation energies of 5.6 meV and 1.5 meV above and below 10K respectively. One may be quick to associate such discrepancies to the difference in scattering rates but the weakly temperature dependent scattering rate is only a moderate modification compared to the exponential dependence of the dc conductivity. Recalculating the plasma frequency with our extracted dc conductivity but with the scattering rate reported by Gorshunov et al. results in activated energies of 12 meV and 2 meV, in better agreement but still only about 65% the values reported in Ref. [35].
Our results regarding the localized response are in better quantitative agreement with Ref. [35], although important differences still exist. Gorshunov et al. identify a "bump" in the optical conductivity at 0.72 THz which was fit with a Drude-Lorentz oscillator and used to model the localized component of the optical conductivity. The bump was attributed to an in-gap impurity band and thus all the localized conductivity was assumed to be related to impurities. However, as seen in Figure 1(b), we have not observed such a feature in any of our measurements of SmB 6 and speculate that this feature may have been an experimental artifact caused by standing wave resonances that occur in backwards wave oscillator setups as was used in Ref. [35]. We therefore make no assumptions about the functional form of the localized conductivity with frequency in our analysis. It should be noted that despite this difference, Gorshunov et al. find the localized conductivity to be only weakly temperature dependent below 20K, supporting our assumption that the localized contribution is temperature independent over the same range.
Such distinctions between our experimental results and that of Ref. [35] are important as they may alter the interpretation of the data. Gorshunov et al. attribute the different activation energy scales of 19 meV and 3 meV in the free carrier plasma frequency to be the hybridization gap and the energy gap between an impurity band and the bottom of the conduction band respectively. Support for this interpretation was given by the bump in the localized conductivity at 3 meV, the same energy as the activation observed in the plasma frequency below 15 K. However, as we have discussed, our experiments observe different activation behavior and no corresponding bump in the localized conductivity. Moreover, Gorshunov et al.'s bump was only a weak maximum in a large background of conduction, and it is not clear, even if such a band exists, why it would manifest in the dc data with an activated temperature dependence. Given the results presented here, the activated energy scales in the plasma frequency may require reinterpretation.
Still, while we do not observe a maximum in the conductivity, we do observe a shift in its frequency dependence at the bulk activation energy scale as shown in Figure 3(a). The origin of this shift is unclear, although suggestions can be found in both impurity and neutral Fermi surface models. For instance, Kondo impurity models predict that a finite impurity concentration smears out the peak in optical conductivity at the direct gap, leading to a tail of conduction which extends down to the indirect gap [43]. One may then interpret the 4 meV activation energy scale of the bulk as the indirect gap, with ac conduction below this energy scale stemming from localized impurity states which do not participate in the dc transport. However, the same argument could be made in the case of a neutral Fermi surface, which, being charge neutral, would also be inert to dc transport experiments.
Additional information regarding the origin of the localized conductivity is provided by the spectral weight analysis shown in Figure 3(b), from which we found an approximate charge density of n ≈ 1 electron / 1000 unit cells. It should be noted that such an analysis comes with large caveats. In general, one must integrate up to frequencies of order the unrenormalized electronic bandwidth in order to infer the charge density or band mass from the conductivity sum rule. Here the integration was performed only to the hybridization gap edge, as the conductivity is known to rise by several orders of magnitude here [35]. However, it is not obvious that the in-gap conduction must end at the hybridization gap edge. Furthermore, our calculation was conducted under the assumption that the effective mass was that of the free electron mass, which likely is not the case as evidenced by quantum oscillations experiments [25] which observe a mass of 0.18m e up to 10K. Repeating the calculation with this effective mass lowers the extracted charge density to n ≈ 1 electron / 5000 unit cells. In contrast, if a "heavy" mass is used then the charge density per unit cell can be significantly larger. Thus, the uncertainty on this charge density is large. Still, such an quasi-free electron analysis is enough to obtain an approximate understanding of the scale of the total number of charge carriers. With these important considerations in mind, we now compare this value to the expectations of both impurity and neutral Fermi surface models.
Taken at face value this charge density is roughly consistent with what one might expect from impurities. For instance, our extracted charge density is about 10 times larger than the charge density at the metal-insulator transition of Si:P [45]. However, it is also about a factor of 10 less than the percolation threshold predicted by Kondo impurity models, which suggest that only a few percent impurity concentration is needed to effectively close the Kondo gap [43,49,50]. Given the large error bars on our extracted charge density, we can only remark that the extracted charge density is in general alignment with such theories.
A comparison can also be made to models of an in-gap neutral Fermi surface. Before proceeding it should be noted that it is not obvious how the conductivity sum rule used in this fashion applies in the case of a neutral Fermi surface. As we mentioned, performing the sum in Eq. 4 to frequencies a few times the bandwidth in conventional metals allows one to extract the band mass. What an analogous sum performed only over low frequencies in the case of a neutral Fermi surface tells us is, to the best of our knowledge, not yet known. We hope that this analysis may inspire future theoretical investigations and we speculate that such a general statement about the sum rules may be more accessible than detailing the precise shape of the optical conductivity in such models.
Still, comparisons can be made. For instance, in the model of Refs. [39,58], a neutral Fermi surface arises through fractionalization of f -holes into separate holon and spinon quasiparticles. Strong binding between conduction d-electrons and the holons are proposed to form a charge neutral fermionic composite exciton (FCE) which gives rise to a neutral Fermi surface in the appropriate limits. In the context of this model the FCE density is found to be identical to the d-electron density, i.e. of order n FCE ≈ 1 / unit cell. One may then insert this charge density into our sum rule analysis and instead ask what is the effective mass of these excitons. Interpreting the result of our sum rule analysis in this fashion suggests an effective mass of m * ≈ 1000m e . How does this compare to the model of Ref. [39]? The effective mass of the FCE's may be inferred from the inverse of their hopping amplitude, m * FCE ∝ U df /t f t d , where t f and t d are the hopping amplitudes of the f -holes and d-electrons respectively and U df is the Coulomb repulsion between f and d electrons. As the f bands are nearly flat, t f is expected to be quite small, while the U df is expected to be a large energy scale of the system. Thus, one expects a very large mass enhancement for the FCE's, consistent with the results of our sum rule analysis.
Conclusion
In this work, the optical conductivity of the Kondo insulator SmB 6 was shown to possess distinct regimes in which the conductivity is dominated by either free carrier or localized contributions. The free carrier response, dominant at temperatures above 10K, was analyzed in the context of the Drude model and found to be generally consistent with previous measurements, although quantitative differences were found and discussed. The localized response, which becomes dominant at the lowest temperatures, was analyzed in the context of models of disordered insulators and recent developments which suggest a potentially neutral Fermi surface forms within the gap of SmB 6 . We found, through a conductivity sum rule analysis that the charge density or effective mass of this localized response is in reasonable agreement with models of both impurities and a neutral Fermi surface within the gap of SmB 6 in the appropriate limits. Our results have shed further light on the mysterious in-gap conduction of SmB 6 and our hope is that these measurements will inspire future investigations into the properties of this remarkable material.
Fig. 1 .
1(a,b) Magnitude of the complex transmission, as defined in Eq. 1, as a function of frequency and temperature for a representative sample grown by the optical floating zone method with thickness d = 22 µm. (b) Real part of the optical conductivity. σ 1 (ω, T ), extracted from the transmission shown in (a) by numerical inversion of Eq. 1.
Fig. 2 .
2Analysis of the free carrier response of SmB 6 . (a) Free carrier conductivity (dashed lines) with corresponding fits to the Drude model (solid lines) as a function of temperature. (b) Temperature dependence of the dc conductivity (blue squares) with a corresponding exponential fit (red dashed line) from which an activation gap of 4.14 meV is extracted. Also shown is the temperature dependence of the minimum conductivity (black circles). Inset: Temperature dependence of the scattering rate. (c) Arrhenius plot of the plasma frequency where two activation energy scales can be observed in distinct temperature regimes. The black dashed line is a fit with
Fig. 3 .
3(a) The real part of the conductivity of SmB 6 at 1.6K, identified here as the conductivity of the in-gap localized response. A shift in frequency dependence at the activated bulk energy scale is observed. (b) The optical conductivity of the localized states extrapolated from zero frequency to the hybridization gap edge. The gray shaded region represents a rough approximation of the spectral weight of this band from which the charge density or effective mass can be extracted, see text for details.
Magnetic and semiconducting properties of SmB 6. A Menth, E Buehler, T H Geballe, Phys. Rev. Lett. 22A. Menth, E. Buehler, T. H. Geballe, Magnetic and semiconducting properties of SmB 6 , Phys. Rev. Lett. 22 (1969) 295-297.
Physical properties of SmB 6. J C Nickerson, R M White, K N Lee, R Bachmann, T H Geballe, G W Hull, Phys. Rev. B. 3J. C. Nickerson, R. M. White, K. N. Lee, R. Bachmann, T. H. Geballe, G. W. Hull, Physical properties of SmB 6 , Phys. Rev. B 3 (1971) 2030-2042.
Mixed-valence compounds. C M Varma, Rev. Mod. Phys. 48C. M. Varma, Mixed-valence compounds, Rev. Mod. Phys. 48 (1976) 219-238.
Stabilit des moments magntiques localiss dans les mtaux. B Coqblin, A Blandin, Advances in Physics. 1767B. Coqblin, A. Blandin, Stabilit des moments magntiques localiss dans les mtaux, Advances in Physics 17 (67) (1968) 281-366.
Rare-earth compounds with mixed valencies. N F Mott, Philosophical Magazine. 302N. F. Mott, Rare-earth compounds with mixed valencies, Philosophical Magazine 30 (2) (1974) 403-416.
Topological Kondo insulators. M Dzero, K Sun, V Galitski, P Coleman, Phys. Rev. Lett. 104106408M. Dzero, K. Sun, V. Galitski, P. Coleman, Topological Kondo insulators, Phys. Rev. Lett. 104 (2010) 106408.
SmB 6 : A promising candidate for a topological insulator. T Takimoto, Journal of the Physical Society of Japan. 8012123710T. Takimoto, SmB 6 : A promising candidate for a topological insulator, Journal of the Physical Society of Japan 80 (12) (2011) 123710.
Theory of topological Kondo insulators. M Dzero, K Sun, P Coleman, V Galitski, Phys. Rev. B. 8545130M. Dzero, K. Sun, P. Coleman, V. Galitski, Theory of topological Kondo insulators, Phys. Rev. B 85 (2012) 045130.
Correlated topological insulators with mixed valence. F Lu, J Zhao, H Weng, Z Fang, X Dai, Phys. Rev. Lett. 11096401F. Lu, J. Zhao, H. Weng, Z. Fang, X. Dai, Correlated topological insulators with mixed valence, Phys. Rev. Lett. 110 (2013) 096401.
Cubic topological Kondo insulators. V Alexandrov, M Dzero, P Coleman, Phys. Rev. Lett. 111226403V. Alexandrov, M. Dzero, P. Coleman, Cubic topological Kondo insulators, Phys. Rev. Lett. 111 (2013) 226403.
Surface Hall effect and nonlocal transport in SmB 6 : Evidence for surface conduction. D J Kim, S Thomas, T Grant, J Botimer, Z Fisk, J Xia, Scientific Reports. 33150D. J. Kim, S. Thomas, T. Grant, J. Botimer, Z. Fisk, J. Xia, Surface Hall effect and nonlocal transport in SmB 6 : Evidence for surface conduction, Scientific Reports 3 (3150).
Topological surface state in the Kondo insulator samarium hexaboride. D J Kim, J Xia, Z Fisk, Nature Materials. 13D. J. Kim, J. Xia, Z. Fisk, Topological surface state in the Kondo insulator samarium hexaboride, Nature Materials 13 (2014) 466- 470.
Low-temperature surface conduction in the Kondo insulator SmB 6. S Wolgast, C Kurdak, K Sun, J W Allen, D.-J Kim, Z Fisk, Phys. Rev. B. 88180405S. Wolgast, C. Kurdak, K. Sun, J. W. Allen, D.-J. Kim, Z. Fisk, Low-temperature surface conduction in the Kondo insulator SmB 6 , Phys. Rev. B 88 (2013) 180405.
Magnetoresistance evidence of a surface state and a fielddependent insulating state in the Kondo insulator SmB 6. F Chen, C Shang, Z Jin, D Zhao, Y P Wu, Z J Xiang, Z C Xia, A F Wang, X G Luo, T Wu, X H Chen, Phys. Rev. B. 91205133F. Chen, C. Shang, Z. Jin, D. Zhao, Y. P. Wu, Z. J. Xiang, Z. C. Xia, A. F. Wang, X. G. Luo, T. Wu, X. H. Chen, Magnetoresistance evidence of a surface state and a field- dependent insulating state in the Kondo insulator SmB 6 , Phys. Rev. B 91 (2015) 205133.
Hybridization, inter-ion correlation, and surface states in the Kondo insulator SmB 6. X Zhang, N P Butch, P Syers, S Ziemak, R L Greene, J Paglione, Phys. Rev. X. 311011X. Zhang, N. P. Butch, P. Syers, S. Ziemak, R. L. Greene, J. Paglione, Hybridization, inter-ion correlation, and surface states in the Kondo insulator SmB 6 , Phys. Rev. X 3 (2013) 011011.
. M M Yee, Y He, A Soumyanarayanan, D.-J Kim, Z Fisk, J E Hoffman, arXiv:1308.1085Imaging the Kondo insulating gap of SmB. 6M. M. Yee, Y. He, A. Soumyanarayanan, D.-J. Kim, Z. Fisk, J. E. Hoffman, Imaging the Kondo insulating gap of SmB 6 , arXiv:1308.1085.
G Li, Z Xiang, F Yu, T Asaba, B Lawson, P Cai, C Tinsman, A Berkley, S Wolgast, Y S Eo, D.-J Kim, C Kurdak, J W Allen, K Sun, X H Chen, Y Y Wang, Z Fisk, L Li, Twodimensional fermi surfaces in Kondo insulator SmB. 6G. Li, Z. Xiang, F. Yu, T. Asaba, B. Lawson, P. Cai, C. Tinsman, A. Berkley, S. Wolgast, Y. S. Eo, D.-J. Kim, C. Kurdak, J. W. Allen, K. Sun, X. H. Chen, Y. Y. Wang, Z. Fisk, L. Li, Two- dimensional fermi surfaces in Kondo insulator SmB 6 , Science 346 (6214) (2014) 1208-1212.
Surface electronic structure of the topological Kondo-insulator candidate correlated electron system SmB 6. M Neupane, N Alidoust, S.-Y Xu, T Kondo, Y Ishida, D J Kim, C Liu, I Belopolski, Y J Jo, T.-R Chang, H.-T Jeng, T Durakiewicz, L Balicas, H Lin, A Bansil, S Shin, Z Fisk, M Z Hasan, Nature Comm. 4 (2991M. Neupane, N. Alidoust, S.-Y. Xu, T. Kondo, Y. Ishida, D. J. Kim, C. Liu, I. Belopolski, Y. J. Jo, T.-R. Chang, H.-T. Jeng, T. Durakiewicz, L. Balicas, H. Lin, A. Bansil, S. Shin, Z. Fisk, M. Z. Hasan, Surface electronic structure of the topological Kondo-insulator candidate correlated electron system SmB 6 , Nature Comm. 4 (2991).
Momentum-dependent hybridization gap and dispersive in-gap state of the Kondo semiconductor SmB 6. H Miyazaki, T Hajiri, T Ito, S Kunii, S.-I Kimura, Phys. Rev. B. 8675105H. Miyazaki, T. Hajiri, T. Ito, S. Kunii, S.-i. Kimura, Momentum-dependent hybridization gap and dispersive in-gap state of the Kondo semiconductor SmB 6 , Phys. Rev. B 86 (2012) 075105.
Direct observation of the spin texture in SmB 6 as evidence of the topological Kondo insulator. Z Xu, P K Biswas, J H Dil, D R S , G Landolt, S Muff, C E Matt, X Shi, N C Plumb, M Radovic, E Pomjakushina, K Conder, A Amato, B S V , R Yu, H.-M Weng, Z Fang, X Dai, J Mesot, H Ding, M Shi, Nature Comm. 54566Z. Xu, P. K. Biswas, J. H. Dil, D. R. S., G. Landolt, S. Muff, C. E. Matt, X. Shi, N. C. Plumb, M. Radovic, E. Pomjakushina, K. Conder, A. Amato, B. S. V., R. Yu, H.-M. Weng, Z. Fang, X. Dai, J. Mesot, H. Ding, M. Shi, Direct observation of the spin texture in SmB 6 as evidence of the topological Kondo insulator, Nature Comm. 5 (4566).
Obersvation of possible topological in-gap sufrace states in the Kondo insulator SmB 6 by photoemission. J Jiang, S Li, T Zhang, Z Sun, F Chen, Z R Ye, M Xu, Q Q Ge, S Y Tan, X H Niu, M Xia, B P Xie, Y Li, X H Chen, H H Wen, D L Feng, Nature. Comm. 43010J. Jiang, S. Li, T. Zhang, Z. Sun, F. Chen, Z. R. Ye, M. Xu, Q. Q. Ge, S. Y. Tan, X. H. Niu, M. Xia, B. P. Xie, Y. Li, X. H. Chen, H. H. Wen, D. L. Feng, Obersvation of possible topological in-gap sufrace states in the Kondo insulator SmB 6 by photoemission, Nature. Comm. 4 (3010).
Kondo hybridization and the origin of metallic states at the (001) surface of SmB 6. E Frantzeskakis, N Jong, B Zwartsenberg, Y K Huang, Y Pan, X Zhang, J X Zhang, F X Zhang, L H Bao, O Tegus, A Varykhalov, A Visser, M S Golden, Phys. Rev. X. 341024E. Frantzeskakis, N. de Jong, B. Zwartsenberg, Y. K. Huang, Y. Pan, X. Zhang, J. X. Zhang, F. X. Zhang, L. H. Bao, O. Tegus, A. Varykhalov, A. de Visser, M. S. Golden, Kondo hybridization and the origin of metallic states at the (001) surface of SmB 6 , Phys. Rev. X 3 (2013) 041024.
Interaction driven subgap spin exciton in the Kondo insulator SmB 6. W T Fuhrman, J Leiner, P Nikolić, G E Granroth, M B Stone, M D Lumsden, L Debeer-Schmitt, P A Alekseev, J.-M Mignot, S M Koohpayeh, P Cottingham, W A Phelan, L Schoop, T M Mcqueen, C Broholm, Phys. Rev. Lett. 11436401W. T. Fuhrman, J. Leiner, P. Nikolić, G. E. Granroth, M. B. Stone, M. D. Lumsden, L. DeBeer-Schmitt, P. A. Alekseev, J.- M. Mignot, S. M. Koohpayeh, P. Cottingham, W. A. Phelan, L. Schoop, T. M. McQueen, C. Broholm, Interaction driven subgap spin exciton in the Kondo insulator SmB 6 , Phys. Rev. Lett. 114 (2015) 036401.
Study of the bulk resitivity of SmB 6 below the bulk to surface crossover temperature using non-local corbino transport. Y S Eo, J Lucien, K Sun, C Kurdak, P F S Rosa, Z Fisk, APS March Meeting AbstractY. S. Eo, J. Lucien, K. Sun, C. Kurdak, P. F. S. Rosa, Z. Fisk, Study of the bulk resitivity of SmB 6 below the bulk to surface crossover temperature using non-local corbino transport, APS March Meeting Abstract.
. B S Tan, Y.-T Hsu, B Zeng, M C Hatnean, N Harrison, Z Zhu, M Hartstein, M Kiourlappou, A Srivastava, M , B. S. Tan, Y.-T. Hsu, B. Zeng, M. C. Hatnean, N. Harrison, Z. Zhu, M. Hartstein, M. Kiourlappou, A. Srivastava, M. D.
Unconventional fermi surface in an insulating state. T P Johannes, J.-H Murphy, L Park, G G Balicas, G Lonzarich, S E Balakrishnan, Sebastian, Science. 3496245Johannes, T. P. Murphy, J.-H. Park, L. Balicas, G. G. Lonzarich, G. Balakrishnan, S. E. Sebastian, Unconventional fermi surface in an insulating state, Science 349 (6245) (2015) 287-290.
Specific heat of SmB 6 at very low temperatures. K Flachbart, S Gabni, K Neumaier, Y Paderno, V Pavlk, E Schuberth, N Shitsevalova, Physica B: Condensed Matter. 378380K. Flachbart, S. Gabni, K. Neumaier, Y. Paderno, V. Pavlk, E. Schuberth, N. Shitsevalova, Specific heat of SmB 6 at very low temperatures, Physica B: Condensed Matter 378380 (2006) 610 -611.
Properties of the in-gap states in SmB 6. S Gabáni, K Flachbart, E Konovalova, M Orendác, Y Paderno, V Pavlík, J Sebek, Solid State Communications. 11711S. Gabáni, K. Flachbart, E. Konovalova, M. Orendác, Y. Paderno, V. Pavlík, J.Sebek, Properties of the in-gap states in SmB 6 , Solid State Communications 117 (11) (2001) 641 -644.
Correlation between bulk thermodynamic measurements and the lowtemperature-resistance plateau in SmB 6. W A Phelan, S M Koohpayeh, P Cottingham, J W Freeland, J C Leiner, C L Broholm, T M Mcqueen, Phys. Rev. X. 431012W. A. Phelan, S. M. Koohpayeh, P. Cottingham, J. W. Freeland, J. C. Leiner, C. L. Broholm, T. M. McQueen, Correlation between bulk thermodynamic measurements and the low- temperature-resistance plateau in SmB 6 , Phys. Rev. X 4 (2014) 031012.
Low-temperature conducting state in two candidate topological Kondo insulators: SmB 6 and Ce 3 Bi 4 Pt 3. N Wakeham, P F S Rosa, Y Q Wang, M Kang, Z Fisk, F Ronning, J D Thompson, Phys. Rev. B. 9435127N. Wakeham, P. F. S. Rosa, Y. Q. Wang, M. Kang, Z. Fisk, F. Ronning, J. D. Thompson, Low-temperature conducting state in two candidate topological Kondo insulators: SmB 6 and Ce 3 Bi 4 Pt 3 , Phys. Rev. B 94 (2016) 035127.
. S Molnar, F Holtzberg, A Benoit, A Briggs, J Floquet, J L Tholence, North-HollandValence Instabilities, AmsterdamS. von Molnar, F. Holtzberg, A. Benoit, A. Briggs, J. Floquet, J. L. Tholence, Valence Instabilities, Amsterdam: North- Holland, 1982.
Intermediate-valent SmB 6 and the hybridization model: An optical study. G Travaglini, P Wachter, Phys. Rev. B. 29G. Travaglini, P. Wachter, Intermediate-valent SmB 6 and the hybridization model: An optical study, Phys. Rev. B 29 (1984) 893-898.
Microwave conductivity of SmB 6. C M Jackson, G Grüner, Z Fisk, S Molnar, Phys. Rev. B. 29C. M. Jackson, G. Grüner, Z. Fisk, S. von Molnar, Microwave conductivity of SmB 6 , Phys. Rev. B 29 (1984) 4786-4788.
Low-energy optical excitation in rare-earth hexaborides. S Kimura, T Nanba, S Kunii, T Kasuya, Phys. Rev. B. 50S.-i. Kimura, T. Nanba, S. Kunii, T. Kasuya, Low-energy optical excitation in rare-earth hexaborides, Phys. Rev. B 50 (1994) 1406-1414.
T Nanba, H Ohta, M Motokawa, S Kimura, S Kunii, T Kasuya, Gap state of SmB. 6T. Nanba, H. Ohta, M. Motokawa, S. Kimura, S. Kunii, T. Kasuya, Gap state of SmB 6 , Physica B: Condensed Matter 186 (1993) 440 -443.
Low-energy electrodynamics of SmB 6. B Gorshunov, N Sluchanko, A Volkov, M Dressel, G Knebel, A Loidl, S Kunii, Phys. Rev. B. 59B. Gorshunov, N. Sluchanko, A. Volkov, M. Dressel, G. Knebel, A. Loidl, S. Kunii, Low-energy electrodynamics of SmB 6 , Phys. Rev. B 59 (1999) 1808-1814.
Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB 6 single crystals. N J Laurita, C M Morris, S M Koohpayeh, P F S Rosa, W A Phelan, Z Fisk, T M Mcqueen, N P Armitage, Phys. Rev. B. 94165154N. J. Laurita, C. M. Morris, S. M. Koohpayeh, P. F. S. Rosa, W. A. Phelan, Z. Fisk, T. M. McQueen, N. P. Armitage, Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB 6 single crystals, Phys. Rev. B 94 (2016) 165154.
Majorana fermi sea in insulating SmB 6 : A proposal and a theory of quantum oscillations in Kondo insulators. G Baskaran, arXiv:1507.03477G. Baskaran, Majorana fermi sea in insulating SmB 6 : A proposal and a theory of quantum oscillations in Kondo insulators, arXiv:1507.03477.
O Erten, P.-Y Chang, P Coleman, A M Tsvelik, arXiv:1701.06582Skyrme insulators: insulators at the brink of superconductivity. O. Erten, P.-Y. Chang, P. Coleman, A. M. Tsvelik, Skyrme insulators: insulators at the brink of superconductivity, arXiv:1701.06582.
D Chowdhury, I Sodemann, T Senthil, arXiv:1706:00418Mixed-valence insulators with neutral fermi-surfaces. D. Chowdhury, I. Sodemann, T. Senthil, Mixed-valence insulators with neutral fermi-surfaces, arXiv:1706:00418.
Local density of states in the vicinity of a Kondo hole. R Sollie, P Schlottmann, Journal of Applied Physics. 7010R. Sollie, P. Schlottmann, Local density of states in the vicinity of a Kondo hole, Journal of Applied Physics 70 (10) (1991) 5803-5805.
Impurity bands in Kondo insulators. P Schlottmann, Phys. Rev. B. 46P. Schlottmann, Impurity bands in Kondo insulators, Phys. Rev. B 46 (1992) 998-1004.
Influence of a Kondo-hole impurity band on magnetic instabilities in Kondo insulators. P Schlottmann, Phys. Rev. B. 54P. Schlottmann, Influence of a Kondo-hole impurity band on magnetic instabilities in Kondo insulators, Phys. Rev. B 54 (1996) 12324-12331.
Collapse of the coherence gap in Kondo semiconductors. P S Riseborough, Phys. Rev. B. 68235213P. S. Riseborough, Collapse of the coherence gap in Kondo semiconductors, Phys. Rev. B 68 (2003) 235213.
W T Fuhrman, J R Chamorro, P A Alekseev, J.-M Mignot, T Keller, P Nikolic, T M Mcqueen, C L Broholm, arXiv:1707.03834Screened moments in a Kondo insulator. W. T. Fuhrman, J. R. Chamorro, P. A. Alekseev, J.-M. Mignot, T. Keller, P. Nikolic, T. M. McQueen, C. L. Broholm, Screened moments in a Kondo insulator, arXiv:1707.03834.
Frequency-dependent conductivity of electron glasses. E Helgren, N P Armitage, G Grüner, Phys. Rev. B. 6914201E. Helgren, N. P. Armitage, G. Grüner, Frequency-dependent conductivity of electron glasses, Phys. Rev. B 69 (2004) 014201.
Measurements of the complex conductivity of NbxSi 1−x alloys on the insulating side of the metal-insulator transition. E Helgren, G Grüner, M R Ciofalo, D V Baxter, J P Carini, Phys. Rev. Lett. 87116602E. Helgren, G. Grüner, M. R. Ciofalo, D. V. Baxter, J. P. Carini, Measurements of the complex conductivity of NbxSi 1−x alloys on the insulating side of the metal-insulator transition, Phys. Rev. Lett. 87 (2001) 116602.
A modified 8f geometry with reduced optical aberrations for improved time domain terahertz spectroscopy. N J Laurita, B Cheng, R Barkhouser, V A Neumann, N P Armitage, Journal of Infrared, Millimeter, and Terahertz Waves. 379N. J. Laurita, B. Cheng, R. Barkhouser, V. A. Neumann, N. P. Armitage, A modified 8f geometry with reduced optical aberrations for improved time domain terahertz spectroscopy, Journal of Infrared, Millimeter, and Terahertz Waves 37 (9) (2016) 894-902.
. N F Mott, Valence Instabilities, 397North-Holland, AmsterdamN. F. Mott, Valence Instabilities, no. pp. 397 and 403, North- Holland, Amsterdam, 1982.
Effects of magnetic-ion dilution in Kondo insulators. T Mutou, Phys. Rev. B. 64165103T. Mutou, Effects of magnetic-ion dilution in Kondo insulators, Phys. Rev. B 64 (2001) 165103.
Alloying effects of Kondo insulators. Z Li, W Xu, C Chen, M Xiao, Phys. Rev. B. 50Z.-z. Li, W. Xu, C. Chen, M.-w. Xiao, Alloying effects of Kondo insulators, Phys. Rev. B 50 (1994) 11332-11339.
N F Mott, E A Davis, Electronis Processes in Non-Crytalline Materials. OxfordOxford University PressN. F. Mott, E. A. Davis, Electronis Processes in Non-Crytalline Materials, Oxford University Press, Oxford, 1979.
Zero-phonon ac hopping conductivity of disordered systems. B I Shklovskiȋ, A L Éfros, Eksp. Toer. Fiz. 81B. I. Shklovskiȋ, A. L.Éfros, Zero-phonon ac hopping conductivity of disordered systems, Eksp. Toer. Fiz. 81 (1981) 406-415.
Are Kondo insulators gapless?. P Coleman, E Miranda, A Tsvelik, Physica B: Condensed Matter. 186P. Coleman, E. Miranda, A. Tsvelik, Are Kondo insulators gapless?, Physica B: Condensed Matter 186 (1993) 362 -364.
Power-law conductivity inside the mott gap: Application to κ-(BEDT-TTF) 2 Cu 2 (CN) 3. T.-K Ng, P A Lee, 10.1103/PhysRevLett.99.156402Phys. Rev. Lett. 99156402T.-K. Ng, P. A. Lee, Power-law conductivity inside the mott gap: Application to κ-(BEDT-TTF) 2 Cu 2 (CN) 3 , Phys. Rev. Lett. 99 (2007) 156402. doi:10.1103/PhysRevLett.99.156402.
Electron self-trapping in intermediatevalent SmB 6. S Curnoe, K A Kikoin, Phys. Rev. B. 61S. Curnoe, K. A. Kikoin, Electron self-trapping in intermediate- valent SmB 6 , Phys. Rev. B 61 (2000) 15714-15725.
N P Armitage, arXiv:0908.1126Electrodynamics of correlated electron systems. N. P. Armitage, Electrodynamics of correlated electron systems, arXiv:0908.1126.
G D Mahan, Many-Particle Physics. Plenum2nd EditionG. D. Mahan, Many-Particle Physics, 2nd Edition, Plenum, 1990.
I Sodemann, D Chowdhury, T Senthil, arXiv:1708.06354Quantum oscillations in insulators with neutral Fermi surfaces. I. Sodemann, D. Chowdhury, T. Senthil, Quantum oscillations in insulators with neutral Fermi surfaces, arXiv:1708.06354.
| [
-0.21411946415901184,
-0.08261309564113617,
-0.040701642632484436,
0.1429922878742218,
0.09406398236751556,
0.07303440570831299,
0.024174747988581657,
0.0026615546084940434,
-0.024937674403190613,
0.08278916776180267,
-0.010022852569818497,
-0.1667388379573822,
-0.0614195391535759,
-0.1263... |
Influência da fisioterapia aquática na função motora grossa de indivíduos com paralisia cerebral: revisão sistemática
Kaitiana Martins kaitianafisio@gmail.com
D A Silva
Adriana Fiumi afiumi@aacd.org.br
Eloisa Morais Machado
Caio Roberto
Aparecido De
Paschoal Castro caio.paschoal11@hotmail.com
Douglas Martins Braga
Kaitiana Martins Da Silva
CaioEloisa Morais Machado elomoraismachado@outlook.com
Roberto Aparecido
Fisioterapeuta do setor de fisioterapia aquática da Associação de Assistência à Criança Deficiente (AACD)
São PauloSPBrasil
Fisioterapeuta do setor de fisioterapia aquática da AACD
São PauloSPBrasil
Fisioterapeuta aluna do Aperfeiçoamento em Fisioterapia nas Disfunções Neurológicas da Criança e do Adulto da AACD
São PauloSPBrasil
Fisioterapeuta do setor de fisioterapia aquática da AACD
São PauloSPBrasil
Supervisor de reabilitação do setor de fisioterapia aquática da AACD
São PauloSPBrasil
Cadernos de Pós-Graduação em Distúrbios do Desenvolvimento
Influência da fisioterapia aquática na função motora grossa de indivíduos com paralisia cerebral: revisão sistemática
AB7D4912D786044ABBCC5DDC89EFB95910.5935/cadernosdisturbios.v22n1p39-50HydrotherapyAquatic therapyFunctionalityMotor skillsCerebral palsy
acrônimo "Pico".Os critérios de inclusão foram intervenção da fisioterapia aquática em crianças e/ou adolescentes com PC; estudos clínicos controlados e não controlados; estudos clínicos randomizados e não randomizadosduplos-cegos ou não.Excluíram-se estudos com populações mistas e outros diagnósticos, adultos, estudos do tipo revisões sistemáticas com ou sem metanálise, relato de casos, série de casos e com outro tipo de desfecho que não seja a função motora.A avaliação metodológica foi realizada por meio da escala PEDro.Identificaram-se, então, 43 estudos nas buscas.Desses, 37 foram excluídos após leitura de título, resumo e métodos, sendo o motivo, em sua maioria, desfechos ou população distintos, resultando em seis estudos elegíveis.Como conclusão, obtivemos que as evidências sobre a fisioterapia aquática em indivíduos com PC são limitadas.Ainda assim, essa terapia é viável e os efeitos adversos são mínimos.Mais pesquisas são necessárias para determinar a eficácia da fisioterapia aquática nessa população nos diferentes níveis do Sistema de Classificação da Função Motora Grossa (GMFCS).Palavras-chaveHidroterapia.Fisioterapia aquática.Funcionalidade.Habilidades motoras.Paralisia cerebral.
A paralisia cerebral (PC) trata-se de um grupo de desordens não progressivas do desenvolvimento, decorrentes de uma lesão no encéfalo imaturo, repercutindo em limitações funcionais.Distúrbios de movimento podem ser acompanhados por alterações sensoriais, perceptuais, cognitivas, comunicacionais e comportamentais.Para a reabilitação desses indivíduos, a fisioterapia aquática é amplamente utilizada.Dessa forma, o objetivo desta revisão é investigar a qualidade dos estudos e a influência da fisioterapia aquática em indivíduos com PC.As buscas foram realizadas nas bases de dados PubMed, Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs), MedLine, Scientific Electronic Library Online (Scielo), Physiotherapy Evidence Database (PEDro) e Biblioteca Virtual em Saúde com base no Influencia de la fisioterapia acuática en la función motora gruesa de personas con parálisis cerebral: una revisión sistemática Resumen La parálisis cerebral (PC) es un grupo de trastornos del desarrollo no progresivos, resultantes de una lesión en el cerebro inmaduro, resultando en limitaciones funcionales.Los trastornos del movimiento pueden ir acompañados de cambios sensoriales, perceptivos, cognitivos, de comunicación y de comportamiento.Para la rehabilitación de estos individuos, la fisioterapia acuática es muy utilizada.Por lo tanto, el objetivo de esta revisión es investigar la calidad de los estudios y la influencia de la fisioterapia acuática en personas con PC.Se realizaron búsquedas en las siguientes bases de datos PubMed, Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs), MedLine, Scientific Electronic Library Online (Scielo), Physiotherapy Evidence Database (PEDro) y Biblioteca Virtual em Saúde, con base en la sigla "Pico".Los criterios de inclusión fueron intervención de fisioterapia acuática en niños y/o adolescentes con PC, estudios clínicos controlados y no controlados, estudios clínicos aleatorizados y no aleatorizados, doble ciego o no.Se excluyeron estudios con poblaciones mixtas y otros diagnósticos, adultos, estudios del tipo revisión sistemática con o sin metanálisis, reportes de casos, series de casos y con cualquier tipo de desenlace diferente a la función motora.La evaluación metodológica se realizó mediante la escala PEDro.Se identificaron 43 estudios en las búsquedas.De estos, 37 fueron excluidos después de leer el título, el resumen y los métodos, debido, en su mayoría, a resultados incorrectos o población incorrecta, lo que resultó en seis estudios elegibles.En conclusión, la evidencia sobre la fisioterapia acuática en personas con PC es limitada, pero esta terapia es factible y los efectos adversos son mínimos.Se necesita más investigación para determinar la efectividad de la fisioterapia acuática en esta población en diferentes niveles del Sistema de Clasificación de la Función Motora Gruesa (Sistema de Classificação da Função Motora Grossa [GMFCS]).
Palabras clave
Hidroterapia.Fisioterapia acuática.Funcionalidad.Motricidad.Parálisis cerebral.
INTRODUÇÃO
A paralisia cerebral (PC) trata-se de um grupo de desordens permanentes do desenvolvimento, do movimento e da postura, causada por uma lesão no cérebro imaturo.Essas disfunções repercutem na limitação funcional desses indivíduos.As desordens motoras podem ser acompanhadas por alterações sensoriais, perceptuais, cognitivas, comunicacionais, comportamentais, crises convulsivas e disfunções musculoesqueléticas secundárias (ROSENBAUM et al., 2006).A incidência da PC no mundo é de 2:1.000 nascidos vivos e é considerada a deficiência física mais comum na infância (O'SHEA, 2008;CANS et al., 2009).Não encontramos dados epidemiológicos sobre a incidência da PC no Brasil.No entanto, estimam-se 17.000 novos casos de PC por ano (GUIMARÃES et al., 2014).
A reabilitação desses indivíduos visa a maior independência e funcionalidade e desenvolvimento das habilidades motoras, dos cuidados pessoais e da inserção social (KETELAAR et al., 2001).Entre as intervenções utilizadas, a fisioterapia aquática é amplamente aplicada.Utilizando-se os efeitos dos princípios físicos e termodinâmicos da água sobre o corpo em imersão, essa modalidade terapêutica pode trazer benefícios específicos, entre os quais, a transferência das habilidades funcionais adquiridas no meio líquido para o solo é essencial (SILVA; BRANCO, 2011;COLE;BECKER, 2004).
O ambiente aquático diminui a sobrecarga articular e permite o aumento dos graus de liberdade de movimentos (KELLY;DARRAH, 2007;CAROMANO KUGA;PASSARELLA, 1998).As propriedades físicas da água e as atividades propostas pelo fisioterapeuta podem facilitar ou dificultar os movimentos, dependendo dos objetivos a serem alcançados (SHIWA et al., 2011).
A função motora grossa define habilidades funcionais, desde as trocas posturais e deslocamentos baixos até o equilíbrio e a marcha (ROSENBAUM
MÉTODO
Realizou-se uma revisão bibliográfica entre março e junho de 2020, sem restrições de idiomas e datas de publicação, buscando periódicos nacionais e internacionais nas bases de dados PubMed, Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs), MedLine, Scientific Electronic Library Online (Scielo), Physiotherapy Evidence Database (PEDro) e Biblioteca Virtual em Saúde.Os termos utilizados para as buscas foram: cerebral palsy, aquatic physiotherapy, hydrotherapy, swimming, aquatic exercises, balneotherapy, pool therapy, water exercises, halliwick e gross motor.
Foram selecionados os artigos que atenderam aos seguintes critérios de inclusão: intervenção da fisioterapia aquática em crianças e/ou adolescentes com PC; ensaios clínicos controlados ou não controlados; ensaios clínicos aleatorizados ou não aleatorizados, com ou sem cegamento.Excluíram-se os estudos sobre populações mistas ou com outros diagnósticos, adultos, estudos do tipo revisão sistemática, relato ou série de casos, ou com outro tipo de desfecho que não fosse a função motora.
Os estudos selecionados deveriam responder ao acrônimo Pico (people, intervention, comparison, outcome): a) "P" -população: paralisia cerebral; b) "I" -intervenção: fisioterapia aquática; c) "C" -comparador: qualquer intervenção; d) "O" -desfecho: função motora.
Esses estudos foram submetidos a avaliação metodológica por meio da escala Physiotherapy Evidence Database (PEDro), para pontuar a qualidade desses artigos.
A escala PEDro é composta por 11 itens e foi elaborada para avaliar a validade interna dos estudos, bem como identificar se as informações contidas podem ser analisadas.Os itens são especificação dos critérios de inclusão (item não pontuado); alocação aleatória dos sujeitos; sigilo na alocação; similaridade dos grupos na fase inicial ou basal; mascaramento dos sujeitos; mascaramento do terapeuta; mascaramento do avaliador; medida de pelos menos um desfecho primário em 85% dos sujeitos alocados; dados analisados pela internação de tratar; comparação estatística entre grupos de pelo menos um desfecho primário; relato de medidas de variabilidade e estimativa dos parâmetros de pelo menos uma variável primária (MAHER et al., 2003).É atribuído um ponto para cada item presente nos estudos e zero é atribuído na ausência de cada item.O score total é determinado pela soma da pontuação, exceto o item 1, sendo a pontuação máxima dez pontos (AKINOLA; GBIRI; ODEBIYI, 2019).
Na atual revisão, a escala foi definida da seguinte forma: um ponto (+) será atribuído em caso de presença de indicadores da qualidade da evidência apresentada e zero pontos (-), atribuído em caso de ausência desses indicadores, (?) indica que não está claro se o critério foi ou não satisfeito.
A metodologia dos estudos incluídos nessa revisão foi apresentada de forma descritiva, considerando o tamanho da amostra, idade dos indivíduos, nível do Sistema de Classificação da Função Motora Grossa (GMFCS), instrumentos de medida, tipo de intervenção e desfechos dos estudos.
RESULTADOS
Foram encontrados 43 estudos.Desses, excluíram-se 37 após leitura do título, resumo e metodologia.Foram incluídos seis estudos que foram lidos na íntegra por todos os pesquisadores.A Figura 1 demonstra o fluxograma do estudo.Os seis artigos foram verificados de acordo com a qualidade metodológica estabelecida pela classificação da escala PEDro.Os scores dos artigos incluídos variaram entre dois e seis, como é possível visualizar na Tabela 1.
Tabela 1
Classificação metodológica avaliada pela escala PEDro
+ + + + ----+ + _ 5
Fonte: Elaborada pelos autores.
A Tabela 2 descreve o tamanho da amostra (n) de cada estudo, idade dos indivíduos e nível do GMFCS.Já a Tabela 3 traz informações relacionadas aos instrumentos de medida da função motora grossa, desenho dos estudos, comparação entre os tipos de intervenção e desfechos dos estudos.Fonte: Elaborada pelos autores.
RESULTADOS E DISCUSSÃO
O objetivo desta revisão foi investigar a qualidade dos estudos e a influência da fisioterapia aquática na função motora grossa de indivíduos com PC.
Auferiu-se que os efeitos da fisioterapia aquática na função motora grossa em crianças com PC são positivos, porém, a qualidade metodológica dos estudos é baixa.
Na escala PEDro, os artigos classificados como moderada a alta qualidade metodológica são os que tem pontuação ≥ 6 (MAHER et al., 2003) et al., 2017;CHRYSAGIS et al., 2009).O tamanho da amostra variou entre dez e 32 indivíduos.Para os grupos que realizaram fisioterapia aquática, as amostras variaram de cinco a 17 indivíduos.Embora não fossem diferentes nos momentos que antecederam as intervenções, os grupos apresentaram níveis funcionais muito variados (AKI-NOLA; GBIRI; ODEBIYI, 2019;LAI et al., 2014;BALLINGTON;NAIDOO, 2018;ADAR et al., 2017;CHRYSAGIS et al., 2009;DIMITRIJEVIĆ et al., 2012).Nenhum dos estudos relatou como foi calculado o tamanho da amostra, sendo esse um fator relevante para a análise dos resultados obtidos.Ainda, a idade dos participantes variou entre quatro e 20 anos e apenas dois estudos incluíram crianças classificadas como nível V do GMFCS no grupo de intervenção aquática (AKINOLA; GBIRI; ODEBIYI, 2019;LAI et al., 2014;BALLINGTON;NAI-DOO, 2018;ADAR et al., 2017;CHRYSAGIS et al., 2009;DIMITRIJEVIĆ et al., 2012).Nesse tocante, acreditamos que estudos que realizem a estratificação do nível de função motora grossa são necessários para a realização de uma análise mais adequada da influência da fisioterapia aquática.
Voltando ao método, o Gross Motor Function Measure (GMFM) foi o instrumento utilizado em todos os estudos (AKINOLA; GBIRI; ODEBIYI, 2019;LAI et al., 2014;BALLINGTON;NAIDOO, 2018;ADAR et al., 2017;CHRYSAGIS et al., 2009;DIMITRIJEVIĆ et al., 2012), uma medida válida, confiável e sensível para habilidades motoras grossas em crianças com PC; entretanto, para crianças mais velhas e com níveis funcionais, um efeito teto pode impedir a detecção de ganhos funcionais (GOMES; ARAÚJO; MACIEL, 2014).
Todos as pesquisas incluídas nessa revisão continham exercícios de aquecimento, seguidos de exercícios específicos na água e finalizavam com um período de desaquecimento (LAI et al., 2014;BALLINGTON;NAIDOO, 2018;ADAR et al., 2017;CHRYSAGIS et al., 2009;DIMITRIJEVIĆ et al., 2012).É relevante mencionar que o conceito Halliwick foi utilizado em dois dos seis estudos (LAI et al., 2014;BALLINGTON;NAIDOO, 2018).
Nos estudos que relataram efeitos favoráveis da fisioterapia aquática para a função motora grossa, as intervenções duraram de oito a 12 semanas, com uma frequência de duas vezes por semana e duração de 30 a 60 minutos para cada sessão (AKINOLA; GBIRI; ODEBIYI, 2019;LAI et al., 2014;BALLING-TON;NAIDOO, 2018).Essas informações sugerem que a duração da sessão, bem como a frequência e o tipo de atividade, pode influenciar no sucesso da intervenção e deve ser considerada no planejamento das intervenções no meio aquático.
CONSIDERAÇÕES FINAIS
A maioria dos estudos contemplados neste trabalho têm baixa qualidade metodológica.As evidências sobre a eficácia da fisioterapia aquática em indivíduos com PC são limitadas.Contudo, a especialidade terapêutica mostra-se viável e traz benefícios para essa população.Mais pesquisas são necessárias para determinar a eficácia da fisioterapia aquática nessa população nos diferentes níveis do GMFCS.Futuros ensaios clínicos aleatorizados e com alta qualidade metodológica fazem-se necessários para delinear a eficácia dos benefícios da fisioterapia aquática para esses indivíduos.
Figura 1
1
Figura 1Diagrama de informações das diferentes fases da revisão sistematizada
Levando-se em consideração as desordens na função motora grossa em indivíduos com PC e os benefícios do ambiente aquático, esse estudo tem o objetivo de investigar a qualidade dos estudos e a influência da fisioterapia aquática na função motora grossa de indivíduos com PC.
Influência da fisioterapia aquática na função motora grossa de indivíduos com paralisia cerebral: revisão sistemática Cadernos de Pós-Graduação em Distúrbios do Desenvolvimento São Paulo, v. 22, n. 1, p. 39-50, jan./jun.2022 http://dx.doi.org/10.5935/cadernosdisturbios.v22n1p39-50 et al., 2006).
. Dentre os Influência da fisioterapia aquática na função motora grossa de indivíduos com paralisia cerebral: revisão sistemática Cadernos de Pós-Graduação em Distúrbios do Desenvolvimento São Paulo, v. 22, n. 1, p. 39-50, jan./jun.2022 http://dx.doi.org/10.5935/cadernosdisturbios.v22n1p39-50 artigos incluídos no presente estudo, apenas dois receberam pontuação seis na escala PEDro, enquanto os demais apresentaram baixa qualidade metodológica.Nesses dois estudos, não foram encontradas diferenças entre o grupo que realizou fisioterapia aquática e o grupo controle, porém nos dois estudos foi verificado que os indivíduos submetidos a fisioterapia aquática obtiveram benefícios relacionados à função motora grossa (ADAR
Kaitiana Martins da Silva, Adriana Fiumi, Eloisa Morais Machado, Caio Roberto Aparecido de Paschoal Castro, Douglas Martins Braga Cadernos de Pós-Graduação em Distúrbios do Desenvolvimento São Paulo, v. 22, n. 1, p. 39-50, jan./jun. 2022 http://dx.doi.org/10.5935/cadernosdisturbios.v22n1p39-50
The effect of aquatic exercise on spasticity, quality of life, and motor function in cerebral palsy. S Adar, 10.5606/tftrd.2017Turkish Journal of Physical Medicine and Rehabilitation. 633
Effect of a 10-week aquatic exercise-training program on gross motor function in children with spastic cerebral palsy. Global Pediatric Health. B Akinola, C Gbiri, D Odebiyi, 10.1177/2333794X19857378jun. 20196
The carry-over effect of an aquatic-based intervention in children with cerebral palsy. S Ballington, R Naidoo, 10.4102/ajod.v7i0.361African Journal of Disability. 72018out
Influência da fisioterapia aquática na função motora grossa de indivíduos com paralisia cerebral: revisão sistemática Cadernos de Pós-Graduação em Distúrbios do Desenvolvimento São Paulo. C Cans, 10.1111/j.1469-8749.2007.tb12626.xDOI 10.1590/fpusp. v5i1.76912Revista de Fisioterapia da Universidade de. 491jun. 2009. jan./jun. 1998. jan./jun. 2022Recommendations from the SCPE collaborative group for defining and classifying cerebral palsy. Developmental medicine and Child Neurology
Effects of an aquatic program on gross motor function of children with spastic cerebral palsy. N Chrysagis, 10.4127/jbe.2009.0027Biology of Exercise. 522009
. A J Cole, B E Becker, 10.1016/j.pmrj.2009.05.01Comprehensive. 2004Elsevier
The effect of aquatic intervention on the gross motor function and aquatic skills in children with cerebral palsy. L Dimitrijević, 10.2478/v10078-012-0033-5Journal of Human Kinetics. 322012
Avaliação da função motora grossa pela GMFM pré e pós cirurgia ortopédica de membros inferiores em pacientes com paralisia cerebral. C R A Gomes, I F D Araújo, S C Maciel, mar.2014.DOI10.5935/0104-7795.20140004Acta Fisiátrica. 211
Aspectos clínicos epidemiológicos de crianças com paralisia cerebral assistidas pela clínica escola de Fisioterapia UNIP-São José dos Campos. C Guimarães, Journal of the Health Science Institute -Revista do Instituto de Ciências da Saúde. 3220jun./jul. 2014. 2022
Aquatic exercise for children with cerebral palsy. Developmental medicine and Child Neurology. M Kelly, J Darrah, M Ketelaar, 10.1111/j.1469-8749.2005.tb01091Physical Therapy. 4792007Effects of a functional therapy programa on motor abilities of children with cerebral palsy
Pediatric aquatic therapy on motor function and enjoyment in children diagnosed with cerebral palsy of various motor severities. C Lai, 10.1177/0883073814535491Journal of Child Neurology. 302jun. 2014
Reliability of the PEDro Scale for rating quality of randomized controlled trials. C G Maher, 10.1093/ptj/83.8.713Physical Therapy. 838
Diagnosis, treatment, and prevention of cerebral palsy. O' Shea, T M , dez.2008.DOI10.1097/GRF.0b013e3181870ba7Clinical Obstetrics and Gynecology in Near-Term/Term Infants. 514
DOI 10.1111/ j.1469-8749.2007.tb12610.x Kaitiana Martins da Silva, Adriana Fiumi, Eloisa Morais Machado, Caio Roberto Aparecido de Paschoal Castro, Douglas Martins Braga Cadernos de Pós-Graduação em Distúrbios do Desenvolvimento São Paulo. P Rosenbaum, Developmental Medicine & Child Neurology. 4912006. jan./jun. 2022A report: the definition and classification of cerebral palsy
. 10.5935/cadernosdisturbios.v22n1p39-50
Clinical assessment of spasticity in children with cerebral palsy: a critical review of available instruments. Developmental Medicine & Child Neurology. V A B Scholtes, 10.1017/S0012162206000132200748
PEDro: a base de dados de evidências em fisioterapia. S R Shiwa, 10.1590/S0103-51502011000300017Fisioterapia em Movimento. 243jul./set., 2011
. J Silva, F Branco, Fisioterapia, 2011Artes MédicasSão Paulo
| [
0.029312962666153908,
-0.0651186853647232,
-0.07758864760398865,
0.011356093920767307,
-0.16653349995613098,
-0.07480548322200775,
-0.10680917650461197,
0.10451700538396835,
0.009784398600459099,
0.10528251528739929,
0.27104055881500244,
-0.1603143811225891,
0.03780818358063698,
0.23358638... |
Variability of Mineral Composition of Rice Landraces Collected from Maharashtra, India Variability of Mineral Composition of Rice Landraces Collected from Maharashtra, India
July-September 2019. 2019
V K Kauthale
S M Patil
A D Nalawade
Variability of Mineral Composition of Rice Landraces Collected from Maharashtra, India Variability of Mineral Composition of Rice Landraces Collected from Maharashtra, India
Asian Journal of Dairy and Food Research
38July-September 2019. 201910.18805/ag.DR-1464242Keyword: LandracesMalnutritionMineral contentRice
Micronutrient malnutrition is one of the burning issues in the rice-based diet area throughout the world. The present study aimed at evaluation of the mineral composition of 77 rice landraces collected from various agro-climatic zones of Maharashtra. The hand-mill processed rice grains were analyzed for eight (Na, Mg, K, Ca, Mn, Fe, Co, Cu, and Zn) mineral content. Among the mineral contents, the iron content ranged from 2.05 to 12.2 mg/100g, calcium content from 39.2 to 238.47 mg/100g, manganese content from 1.53 to 7.54 mg/100g, copper content from 0.54 to 3.03 mg/100g and zinc content ranged from 2.65 to 11.62 mg/100g.The other minerals, like magnesium content in studied landraces, ranged from 81.72 to 278.56mg/100g, sodium content from 4.73 to 274.34 mg/100g, and potassium content from 148.05 to 670.74 mg/100g. Most of the studied landraces had wide range of variation, rich in minerals and could be a valuable source for bio-fortification of minerals through the breeding method.
IntroductIon
R ice (Oryza sativa L.) is the most important cereal in the world, cultivated in a large area. It is a staple food for nearly half of the world's seven billion people (IRRI, 2013). Rice is low in fat and high in starchy carbohydrates, packed full of vitamins and minerals, and provides an excellent source of vitamin E, B vitamins (thiamine, niacin) and Potassium (Renuka et al., 2016). Unfortunately, rice is lacking many essential minerals as iron, zinc and vitamin A. Thus, a ricebased diet is the primary cause of micronutrient malnutrition throughout much of the developing world. Iron, zinc, and vitamin A deficiencies are common in rice-consuming regions (http://www.goldenrice.org/Content2-How/how6_mn.php). Micronutrient malnutrition resulting from the consumption of diets deficient in minerals, vitamins, and essential amino acids affects more than one-half of the world's population, especially women and children in developing countries (UNSCN, 2004, Datta et al., 2006. These deficiencies result in decreased work productivity, reduced mental capacity, stunting, blindness, increased child mortality, and elevated morbidity and mortality in general (http://www.goldenrice. org/Content2-How/how6_mn.php). One of the interventions against micronutrient malnutrition is the breeding of crops through conventional or genetic engineering to accumulate micronutrients in the edible portion (Stein, 2010). Various workers pointed out that the identification of genetic resources with high levels of targeted micronutrients is a necessary step to enhance micronutrient levels through conventional plant breeding (Ortiz-Monasterio et al., 2007;Bouis, 2000). The collection and characterization and screening for desirable characters become fundamental steps towards the genetic improvement of crops. The crop landraces are being served as a valuable gene pool as they contain locally adapted alleles and represent an irreplaceable bank of highly co-adapted genotypes (Qualset et al., 1997). However, with the introduction of an industrial production system, crop diversity is the major victim. Therefore, conservation of this valuable gene pool is need of the hour. The objective of present work was to determine the mineral content of rice landraces collected from tribal areas of Maharashtra, India, which will reveal nutritive properties of these unexplored rice landraces and their possible use in breeding programs. Additionally, this study will contribute to the enrichment of food nutrition database.
MAterIAls A n d M e t h o d s
The 77 landraces of rice have been collected from native farmers in Jawhar (Palghar), Akole (Ahmednagar), Junner (Pune), and Etapalli (Gadchiroli) blocks in Maharashtra. The field experiments were conducted during Kharif 2017 at village level in-situ conservation centers of BAIF Development Research Foundation, and seed samples were collected at crop harvest. The hand-mill processed seed samples collected from these in-situ centers were used for analysis. Grain samples were analyzed at the National Agri-Food Biotechnology Institute (NABI), Mohali, Chandigarh. Samples of 0.1 g were digested with 10 mL of ICP-MS grade nitric acid and diluted to 50 ml with MQ water. After digestion, the solution was examined for eight elements (Na, Mg, K, Ca, Mn, Fe, Co, Cu, and Zn) content using Agilent 7700 series Inductively Coupled Plasma Mass Spectrometry (ICP-MS).
results A n d d I s c u s s I o n s
Results of the present study on eight mineral contents in 77 rice landraces showed that many rice landraces are with a wide range of minerals; the result of the analysis is given in Annexure 1. Figure 1 shows the landraces with higher levels of Fe (5 to 12.51 mg/100g), Na (50 to 274.34 mg/100g), Mg (140 to 278 mg/100g), K (350 to 670 mg/100g), Ca (85 to 238.47 mg/100g), Mn (4 to 7.53 mg/100g), Cu (1 to 3 mg/100g) and Zn (5 to 11.62 mg/100g) among studied 77 landraces.
The calcium content in studied landraces ranged from 39.2 to 238.47 mg/100g, and 31 landraces showed more than 85-mg/100g calcium. Among those landraces, Khadkya (238.47 mg/100 g), Mahadi (197.05 mg/100 g), Hali kolpi (194.98 mg/100 g), Dangi-red (180.82 mg/100 g) and Varangal (179.92 mg/100 g) were found with the highest calcium content. Thomas et al. (2015) reported 12.42 to 21.38 mg/100 g calcium in different rice varieties. The iron content in studied landraces ranged from 2.05-12.2 mg/100g. About 55 landraces found with more than 5 mg/ 100g of iron content. Kalbhat (12.21 mg/100 g), Khadkya (11.51 mg/100 g), Jay-shriram (11.37 mg/100 g), Tornya (9.64 mg/100 g) and Masala (8.98 mg/100 g) were found with highest iron content. Iron deficiency is the most common nutritional disorder in the world, affecting over 4 billion people, with more than 2 billion people, mainly in developing countries, actually being anemic [http://www.who.int/nut/ida.htm]. Improved rice varieties developed for higher iron, contains 19.8 to 37.5 ppm (1.98 to 3.75 mg/100g) iron (Ravindra Babu 2013). Among the transgenic lines developed by Krishnan et al. (2009), Fe content was recorded 21 mg/kg in the unpolished IR68144 and 15 mg/kg in BR29 and polished rice grains of IR68144 and BR29 it was 15 and 8.9 mg/kg, respectively. The results clearly showed that most of the studied landraces are superior in the matter of iron content.
The magnesium content in studied landraces ranged from 81.72 to 278.56mg/100g. The landraces Tulshya (278.56 mg/100g), Lalkabara (269.87 mg/100g), Hali Kolamba (268.94 mg/100g), Ambemohar (253.52 mg/100g) and Gandha (239.12 mg/100g) were found highest magnesium content. Out of studied 77 landraces, 42 landraces contained magnesium more than 140 mg/100g. The sodium content in studied landraces ranged from 4.73 to 274.34 mg/100g. Thirty-two landraces found more than 50 mg/100g sodium content. Khadkya (274.34 mg/100g), Dhavalbhat (193.18mg/100g), Kamod (173.48mg/100g), Kirtibhat (172.10 mg/100g) and Varangal (170.46mg/100g) landraces found with highest sodium content. The potassium content in studied landraces ranged from 148.05 to 670.74 mg/100g. Tulshya (670.74 mg/100g), Ambemohar (624.45 mg/100g), Namoku (608.12 mg/100g), DRK-2 (596.42 mg/100g) and Lalkabara (577.55 mg/100g) landraces found with highest potassium content. The 38 landraces were contained more than 350 mg/100g potassium. The manganese content in studied landraces ranged from 1.53 to 7.54 mg/100g. Noon (7.54 mg/100g), Pitris (7.52 mg/100g), Tulshya (7.43 mg/100g), Kirtibhat (6.65 mg/100g) and Salbhat (6.57 mg/100g) landraces found with highest manganese content. The 39 landraces contained more than 4 mg/100 g manganese.
The copper content in studied landraces ranged from 0.54 to 3.03 mg/100g. The 45 landraces contained more than 1 mg/100 g copper. Sonphal (3.03 mg/100g), Hali kolpi (2.25 mg/100g), Raibhog (2.06 mg/100g), Kalbhat(2.05 mg/100g) and Garikolapi (1.95 mg/100g) landraces found with highest copper content. Renuka et al. (2016) reported vast variation in 39 rice varieties in respect to zinc content (25µg/g to165 µg/g).
The zinc content in studied landraces ranged from 2.65 to 11.62 mg/100g. Khadkya (11.62 mg/100g), Noon (10.57 mg/100g), Sonphal 9.57 mg/100g), Kirtibhat (9.32 mg/100g) and Varangal (7.68 mg/100g) landraces found with highest zinc content. The 49 landraces contained more than 5 mg/100g zinc. Deb et al., (2015) reported 2.4 to 44.9 mg/kg (0.24 to 4.49 mg/100g) zinc content in 130 rice landraces except for Garibsaal, which is known for its medicinal properties in gastro-intestinal ailments, contains extraordinary amount (155 mg/kg) of zinc. In the present study, also few landraces like Khadkya (11.62 mg/100g) Noon (10.57 mg/100g) and Sonphal (9.57 mg/100g) contain higher zinc. The rice landraces with overall higher mineral contents are depicted in Table 1. Tulashya and Khadkya contain an overall higher amount of most of the minerals among the studied landraces. Several traditional rice varieties are considered in folk medicine to have high nutritive and therapeutic value and found rich in minerals (Deb et al., 2015). The indigenous traditional knowledge indicated that collected landraces are being utilized for various purposes like diet for nursing mothers (Malgudya, Rajgudya, Dhavul), fracture recovery (Mahadi), weakness recovery (Dangi-red, Kasbai) etc. However, these community claims need to be scientifically validated.
conclusIons
The present study reported a wide range of mineral accumulation, including Cu, Fe, Mn, Zn and Mg in handmilled seeds of 77 rice landrace. This has indicated that there is a good scope to locate and promote such high mineralrich varieties for cultivation and human consumption. The outcome of the study will also facilitate plant breeders to choose desired parents for a breeding program to articulate the nutrient-rich varieties and address the malnutrition aspect in regards to most of the cereal crops. Contd....
Figure 1 :
1Number of rice landraces with high levels of minerals in grains
Table 1 :
1Selected rice landraces with highest mineral contents in studied samples (mg/100g)Landraces
Iron
Sodium
Magnesium
Potassium
Calcium
Manganese
Copper
Zinc
Ambemohar
7.24
156.81
253.52
624.45
109.55
6.14
1.61
6.50
Hali Kolamba
5.90
136.74
268.94
560.47
102.80
5.00
1.80
7.08
Kirtibhat
5.16
172.10
198.52
476.46
138.24
6.65
1.58
9.32
Sonphal
7.73
21.84
237.76
531.05
79.18
3.50
3.03
9.57
Tulshya
8.08
144.28
278.56
670.74
94.88
7.43
1.79
7.25
Khadkya
11.51
274.34
228.51
517.83
238.47
5.30
1.87
11.62
Kalbhat
12.21
125.21
205.80
524.31
92.94
5.16
1.70
5.45
Varangal
4.20
170.46
169.30
311.38
179.92
3.90
1.72
7.68
Malghudya
8.52
137.67
147.51
290.64
139.41
2.54
0.93
5.23
Kalbhat
12.21
125.21
205.80
524.31
92.94
5.16
1.70
5.45
Annexure 1: Mineral contents in studied rice landrace samples (mg/100g)Landrace name
Fe
Na
Mg
K
Ca
Mn
Cu
Zn
Chimansal
3.10
9.75
119.08
252.42
42.83
4.62
0.73
2.65
Zini (midlate)
2.73
52.35
100.31
213.97
76.19
2.26
0.67
3.10
Zini early
3.95
58.35
83.93
148.05
96.70
1.65
0.76
3.43
Ehawanji
3.85
5.20
121.20
334.02
42.05
2.52
0.60
3.61
Sapari
3.54
6.06
93.11
359.61
49.19
2.50
0.94
3.66
DRK-1
3.73
7.09
101.34
296.45
64.64
3.13
0.76
3.81
Kasbai
5.22
7.83
141.28
329.71
71.00
4.39
0.94
3.89
DRK-2
4.40
12.23
184.97
596.42
61.26
5.58
0.92
3.89
Yeremalunchi
3.60
7.53
110.79
455.25
48.41
3.37
0.71
4.07
Katewanji
4.31
5.69
139.65
446.14
39.20
4.42
1.08
4.08
Kasvel
3.64
33.37
123.22
240.57
75.54
3.08
0.77
4.09
Karaj
4.77
5.02
141.18
405.62
53.74
4.43
0.90
4.18
Wada zini
2.42
80.00
107.11
195.20
139.02
3.03
0.54
4.18
Lalya
2.83
125.02
153.94
257.67
131.36
2.83
0.79
4.26
Mothilunchi
5.11
8.89
135.79
348.10
53.61
4.03
0.84
4.28
Yerkusuma
3.27
7.22
82.14
223.21
39.98
2.06
0.71
4.29
Dhndhune
2.05
100.18
121.80
208.77
103.84
2.71
1.44
4.33
Sagg
3.79
101.02
132.80
231.26
133.44
5.24
0.86
4.36
Kavala
5.83
71.47
110.17
192.06
117.08
3.47
1.09
4.38
Vakvel
8.53
19.10
148.02
328.70
61.52
2.83
1.54
4.49
Javyachi gundi
3.40
9.67
131.63
323.04
42.18
3.55
1.31
4.56
Kolpi(mid late)
3.50
160.04
103.85
186.48
119.42
3.28
0.89
4.60
Godal
4.58
5.19
183.91
518.34
53.09
6.50
0.91
4.63
Pandharilunchi
5.59
6.77
116.47
284.47
60.87
3.45
0.84
4.88
Padarvanji
4.34
6.42
119.55
317.53
59.19
3.37
1.12
4.90
Lalluchi
3.89
6.53
133.79
304.20
54.39
3.35
0.76
4.94
Tornya
9.64
8.15
160.88
360.15
48.15
4.32
1.40
4.97
Suratikolam
5.64
12.25
141.80
340.73
77.23
4.32
1.44
4.98
Juna 57
4.69
121.05
201.96
530.02
65.55
4.45
1.82
5.01
Masala
8.98
80.50
136.23
252.71
100.86
3.94
1.00
5.05
Ashvini
3.67
119.72
180.93
466.63
74.25
4.90
1.70
5.19
Kalbhat
6.30
134.54
114.99
358.25
86.45
3.80
2.05
5.23
Malghudya
8.52
137.67
147.51
290.64
139.41
2.54
0.93
5.23
Selkavanji
4.18
4.73
108.59
264.11
47.89
3.36
1.34
5.24
Masura
5.63
84.79
172.47
367.33
107.09
4.20
0.74
5.27
Raatbhat
4.06
17.33
98.71
213.72
55.16
3.61
1.04
5.28
Kate chenur
5.99
14.67
188.68
502.70
76.84
5.55
0.94
5.30
Garikolapi
5.07
135.94
126.47
334.84
89.82
1.53
1.95
5.34
Nanded chennur
6.29
20.93
150.65
337.43
98.65
5.12
0.79
5.34
Rajghudya
8.02
18.80
149.62
356.50
106.96
4.06
0.99
5.36
Raibhog
8.43
127.79
153.58
407.05
78.92
2.66
2.06
5.38
Khodakhuri
5.03
8.32
135.27
274.29
74.76
3.92
0.78
5.38
Jiri zini
3.89
120.25
135.65
346.55
83.07
6.05
1.63
5.41
Kalbhat
12.21
125.21
205.80
524.31
92.94
5.16
1.70
5.45
Dhavalbhat
3.05
193.18
143.00
215.03
162.00
2.49
0.77
5.46
Kokade
5.31
4.88
120.86
326.21
52.57
3.57
0.87
5.61
HMT
3.95
13.11
81.72
221.57
56.46
3.33
1.39
5.69
Reganal lunchi
5.04
10.77
108.06
385.84
62.04
2.71
0.74
5.77
Juna kolam
4.50
11.55
113.84
291.80
71.00
5.60
1.25
5.89
Contd....
Jaymahadev
4.27
10.81
151.16
452.47
60.75
5.62
0.98
5.90
Jirvel
7.90
135.33
165.38
434.71
111.50
2.50
1.69
5.97
Sodui
4.15
15.58
182.79
411.74
66.07
4.00
0.96
6.14
Kamal bhat
5.45
140.60
156.97
396.10
83.20
3.96
1.53
6.16
Kamod
4.35
173.48
181.68
411.51
91.25
4.10
1.39
6.19
Sadhana bhat
3.52
124.49
134.48
325.73
62.69
3.58
1.52
6.22
Mahadi (midlate)
6.00
44.66
139.44
262.61
197.05
4.20
1.27
6.27
Dula-2
4.74
24.85
150.93
362.58
56.33
5.26
1.48
6.28
Nanded-92
4.49
15.90
128.21
382.08
91.38
4.24
1.16
6.30
Vijay Nanded
4.37
16.79
121.47
324.14
78.14
3.73
1.04
6.35
Goti
7.20
7.34
212.83
517.56
69.96
4.97
1.27
6.42
Ambemohar
7.24
156.81
253.52
624.45
109.55
6.14
1.61
6.50
Gandha
4.57
7.00
239.12
564.77
61.78
5.87
1.36
6.57
Dangi (red )
3.00
136.99
143.90
293.41
180.82
4.46
1.33
6.59
Lalkabara
6.60
5.12
269.87
577.55
50.88
6.06
1.18
6.63
Salbhat
8.91
10.03
185.27
409.15
54.12
6.57
1.18
6.76
Namoku
6.14
5.99
210.69
608.12
71.13
5.43
1.23
6.78
Pacheki
6.52
125.20
185.85
316.66
146.94
3.84
0.97
7.00
Pitris
5.12
6.95
221.42
496.03
80.61
7.52
1.20
7.02
Hali kolamba
5.90
136.74
268.94
560.47
102.80
5.00
1.80
7.08
Tulshya
8.08
144.28
278.56
670.74
94.88
7.43
1.79
7.25
Jayshriram
11.37
40.18
189.98
481.45
136.17
5.67
1.12
7.39
Hari kolpi
5.26
117.41
187.46
385.69
194.98
2.75
2.25
7.58
Varangal
4.20
170.46
169.30
311.38
179.92
3.90
1.72
7.68
Kirtibhat
5.16
172.10
198.52
476.46
138.24
6.65
1.58
9.32
Sonphal
7.73
21.84
237.76
531.05
79.18
3.50
3.03
9.57
Noon
7.73
7.03
204.11
487.97
88.52
7.54
1.18
10.57
Khadkya
11.51
274.34
228.51
517.83
238.47
5.30
1.87
11.62
Range
2.05
-12.21
4.73-
274.00
81.71-
278.00
148.04-670.00
39.19-
238.47
1.53-
7.53
0.53-
3.03
2.65-
11.62
Asian Journal of Dairy and Food Research, Volume 38 Issue 3 (July-September 2019)
AcknowledgMentThe authors are thankful to Rajiv Gandhi Science and Technology Commission, Government of Maharashtra for financial support; Maharashtra Gene Bank Project team for field support, Dr. Avinash Joshi for his valuable suggestions and National Agri-Food Biotechnology Institute (NABI), Mohali, Chandigarh, India for analysis of rice samples.references
Enrichment of food staples through plant breeding: a new strategy for fighting micronutrient malnutrition. H E Bouis, Nutrition. 16Bouis, H. E. (2000). Enrichment of food staples through plant breeding: a new strategy for fighting micronutrient malnutrition. Nutrition 16, 701-704.
Improved 'golden' indica rice and post-transgeneration enhancement of metabolic target products of carotenoids (b-carotene) in transgenic elite cultivars (IR64 and BR29). K Datta, M Rai, V Parkhi, N Oliva, J Tan, S K Datta, Current Science. 91Datta, K., Rai, M., Parkhi, V., Oliva, N., Tan, J., & Datta, S. K. (2006). Improved 'golden' indica rice and post-transgeneration enhancement of metabolic target products of carotenoids (b-carotene) in transgenic elite cultivars (IR64 and BR29). Current Science, 91, 935-939.
A profile of heavy metals in rice (Oryzasativa ssp. indica) landraces. D Deb, S Sengupta, T Pradeep, Curr Sci. 1093Deb, D., Sengupta, S. and Pradeep,T. (2015). A profile of heavy metals in rice (Oryzasativa ssp. indica) landraces. Curr Sci., 109 (3): 407-409
Trends in global rice consumption. 121Manila, PhilippinesRice Today. International Rice Research Institutehttp://www.goldenrice.org/Content2-How/how6_mn.php http://www.who.int/nut/ida.htm IRRI, 2013. Trends in global rice consumption: Rice Today. International Rice Research Institute, Manila, Philippines.12: 1.
Rice caryopsis structure in relation to distribution of micronutrients (iron, zinc, b-carotene) of rice cultivars including transgenic indica rice. S Krishnan, K Datta, V Parkhi, S K Datta, Plant Sci. 177Krishnan, S., Datta, K., Parkhi,V. and Datta,S. K.(2009). Rice caryopsis structure in relation to distribution of micronutrients (iron, zinc, b-carotene) of rice cultivars including transgenic indica rice. Plant Sci, 177: 557-562.
Enhancing the mineral and vitamin content of wheat and maize through plant breeding. J I Ortiz-Monasterio, N Palacios-Rojas, E Meng, K Pixley, R Trethowan, R J Pena, J Cereal Sci. 46Ortiz-Monasterio, J. I., Palacios-Rojas, N., Meng, E., Pixley,K., Trethowan, R. and R. J. Pena. (2007). Enhancing the mineral and vitamin content of wheat and maize through plant breeding. J Cereal Sci., 46, 293-307.
Locally based crop plant conservation. C O Qualset, A B Damania, A C A Zanatta, S B Brush, Plant Genetic Conservation: The in-situ Approach, ISBN 0412637308. Maxted N., Ford Lloyd B. and Hawkes J.G.LondonChapman & HallQualset, C.O., Damania,A.B., Zanatta,A.C.A. and Brush, S.B. (1997). Locally based crop plant conservation. In: Maxted N., Ford Lloyd B. and Hawkes J.G. (ed.), Plant Genetic Conservation: The in-situ Approach, ISBN 0412637308, Chapman & Hall, London, pp. 160-175.
Importance and advantages of rice biofortification with iron and zinc. Ravindra Babu, V , Journal of SAT Agricultural Research. 11Ravindra Babu V. (2013). Importance and advantages of rice bio- fortification with iron and zinc. Journal of SAT Agricultural Research 11.
Determination of some minerals and b-carotene contents in aromatic indica rice. N Renuka, S V Mathure, R L Zanan, R J Thengane, A B Nadaf, Oryza sativa L.) germplasm. Food Chemistry. 191Renuka, N., Mathure, S. V., Zanan, R. L., Thengane, R. J. and Nadaf, A. B. (2016). Determination of some minerals and b-carotene contents in aromatic indica rice (Oryza sativa L.) germplasm. Food Chemistry 191 2-6
Global impacts of human mineral malnutrition. A J Stein, Plant Soil. 335Stein, A. J. (2010). Global impacts of human mineral malnutrition. Plant Soil,335, 133-154.
Composition of amino Acids, fatty acids, minerals and dietary fiber in some of the local and import rice varieties of Malaysia. R Thomas, R Bhat, Y T Kuang, INT FOOD RES J. 223Thomas, R., Bhat, R. and Kuang,Y.T. (2015). Composition of amino Acids, fatty acids, minerals and dietary fiber in some of the local and import rice varieties of Malaysia. INT FOOD RES J. 22(3): 1148-1155
5 th Report on the world nutrition situation, Nutrition for improvement development outcomes United Nation as system Standing Committee on Nutrition. UNSCN. UNSCN, (2004), 5 th Report on the world nutrition situation, Nutrition for improvement development outcomes United Nation as system Standing Committee on Nutrition, Geneva, Switzerland.
| [
-0.057152144610881805,
-0.05443868786096573,
-0.03528527915477753,
0.11846183240413666,
0.13285589218139648,
0.0006463682511821389,
0.029830623418092728,
0.08811232447624207,
-0.09181231260299683,
-0.006678042933344841,
-0.011878669261932373,
-0.17032989859580994,
0.12895303964614868,
-0.1... |
SOBOLEV STABILITY FOR THE 2D MHD EQUATIONS IN THE NON-RESISTIVE LIMIT
23 Jan 2024
Niklas Knobel
SOBOLEV STABILITY FOR THE 2D MHD EQUATIONS IN THE NON-RESISTIVE LIMIT
23 Jan 202456D1E17C39E231C7605ACC0C6EF3A704arXiv:2401.12548v1[math.AP]Magnetohydrodynamics, stability threshold
In this article, we consider the stability of the 2D magnetohydrodynamics (MHD) equations close to a combination of Couette flow and a constant magnetic field.We consider the ideal conductor limit for the case when viscosity ν is larger than resistivity κ, ν ≥ κ > 0. For this regime, we establish a bound on the Sobolev stability threshold.Furthermore, for κ ≤ ν 3 this system exhibits instability, which leads to norm inflation of size νκ − 1 3 .
Introduction
The equations of magnetohydrodynamics (MHD)
∂ t V + V • ∇V + ∇Π = ν∆V + B • ∇B, ∂ t B + V • ∇B = κ∆B + B • ∇V, ∇ • V = ∇ • B = 0, (t, x, y) ∈ R + × T × R =: Ω,(1)
model the evolution of a magnetic field B : Ω → R 2 interacting with the velocity V : Ω → R 2 of a conducting fluid.The MHD equations are a common model used in astrophysics, planetary magnetism and controlled nuclear fusion [Dav16].
The quantities ν, κ ≥ 0 correspond to fluid viscosity and magnetic resistivity.The pressure Π : Ω → R ensures that the velocity remains divergence-free.A fundamental problem of fluid dynamics and plasma physics is the stability and long-time behavior of solutions to equation (1) and in particular stability of specific solutions.We consider the combination of an affine shear flow, called Couette flow, and a constant magnetic field:
V s = ye 1 , B s = αe 1 .
In particular, the solution combines the effects of mixing due to shear and coupling by the magnetic field.The Couette flow mixes any perturbation, which leads to increased dissipation rates, called enhanced dissipation, and stabilizes the equation.
The coupling with a constant magnetic field propagates this mixing to magnetic perturbations.However, the magnetic field weakens the mixing, especially if viscosity is larger than resistivity, inviscid damping gets counteracted by algebraic growth for specific time regimes.
In the related case of the Navier-Stokes equation, that is when no magnetic field is present, one observes turbulent solutions as viscosity reaches small values.In contrast, the linearized problem around Couette flow is stable for all values of the viscosity.These phenomena are known as the Sommerfeld paradox [LL11] and highlight instability due to nonlinear effects.In [BM15, DM18, DZ21, BM14, IJ13] various authors show sharp stability in Gevrey 2 spaces (spaces between C ∞ and analytic).The nonlinear instability can be suppressed by the viscosity for initial data sufficiently small in Sobolev spaces, ensuring stability [BVW18,MZ22,BGM17].
When considering the MHD equations without Couette flow, the constant magnetic field stabilizes the equation.The dynamics of small initial perturbations of the ideal MHD equation around a strong enough magnetic field is close to the linearized system [BSS88].For stability in several dissipation regimes we refer to [WZ17, RWXZ14, HXY18, RWXZ14, Sch88, CF23, Koz89] and references therein.However, global in time wellposedness for the non-resistive case is still open (see the discussion in [CF23]).Furthermore, a shear flow leads to qualitatively different behavior and instabilities [HT01,HHKL18].
Recently, the MHD equation around Couette flow has gathered significant interest [Lis20,KZ23a,ZZ23,Dol23,KZ23b].Already on a linear level, the behavior of the MHD changes for different values of ν and κ.In [Lis20] Liss proved the first stability threshold for the MHD equations.He considered the full dissipative regime of κ = ν > 0 and proved the stability of the three-dimensional MHD equation for initial data which is sufficiently small in Sobolev spaces.For the analogous two-dimensional problem, Dolce [Dol23] proved stability in the more general setting of 0 < κ 3 ≲ ν ≤ κ.In [KZ23b] Zillinger and the author considered the case of only horizontal resistivity and full viscosity and established stability for small data in Sobolev spaces.For the regime of vanishing viscosity ν = 0 and non-vanishing resistivity κ > 0, in [KZ23a] we constructed a linear stability and instability mechanism around nearby traveling waves in Gevrey 2 spaces.In a corresponding nonlinear stability result, Zhao and Zi [ZZ23] proved the almost matching nonlinear result of Gevrey σ stability for 1 ≤ σ < 2 and for sufficiently small perturbations.
The results mentioned above on stability around Couette flow focus on the setting when resistivity is larger than viscosity ν ≤ κ.Indeed in the setting ν > 0 and κ = 0, the magnetic effects dominate leading to a linear instability mechanism and thus a growth of the magnetic field by νt for specific initial data [KZ23b].
In this paper, we consider the setting 0 < κ ≤ ν.In particular, this also includes the non-resistive limit κ ↓ 0 independent of ν.To the author's knowledge the stability of the regime κ < ν has not previously been studied for the MHD equation around Couette flow.To state the main result, we define the perturbative unknowns
v(x, y, t) = V (x + yt, y, t) − V s , b(x, y, t) = B(x + yt, y, t) − B s ,
where the change of variables x → x + yt follows the characteristics of the Couette flow.For these unknowns, equation (1) becomes
∂ t v + v 2 e 1 − 2∂ x ∆ −1 t ∇ t v 2 = ν∆ t v + α∂ x b + b∇ t b − v∇ t v − ∇ t π, ∂ t b − b 2 e 1 = κ∆ t b + α∂ x v + b∇ t v − v∇ t b, ∇ t • v = ∇ t • b = 0. (2)
Due to the change of variables the spatial derivatives become time-dependent, i.e.
∂ t y = ∂ y − t∂ x , ∇ t = (∂ x , ∂ t y ) T and ∆ t = ∂ 2 x + (∂ t y ) 2 .
For equation (2) we establish Lipschitz stability for initial data which is sufficiently small in Sobolev spaces, in the sense that there exists a bound on the initial data ε 0 = ε 0 (ν, κ) and a Lipschitz constant L = L(ν, κ) such that for initial data which satisfies
∥(v, b) in ∥ H N = ε ≤ ε 0 ,
the corresponding solution is globally bounded in time by
∥(v, b)(t)∥ H N ≤ Lε.
For the non-resistive case, κ = 0, global wellposedness is an open problem and so Lipschitz stability in Sobolev spaces is unclear.Thus, naturally the question arises, which ε 0 and L are optimal and how they behave in the limit ν, κ ↓ 0. We denote a Sobolev stability threshold as γ 1 , γ 2 ∈ R, such that for ε 0 = c 0 ν γ 1 κ γ 2 with small c 0 > 0 we obtain
∥(v, b) in ∥ H N ≤ c 0 ν γ 1 κ γ 2 → stability, ∥(v, b) in ∥ H N ≫ c 0 ν γ 1 κ γ 2 → possible instability.
This extends the common convention in the field (eg.see [BVW18]) to allow for two independent parameters ν and κ.In particular, it agrees with the common convention when restricting to the case ν ≈ κ.It allows us to discuss cases where κ tends to zero much quicker than ν.Establishing a possible instability is highly nontrivial since for the nonlinear setting it is difficult to construct solutions that exhibit norm inflation.To the author's knowledge, there does not exist any nonlinear instability result for the MHD equation around Couette flow in Sobolev spaces.
For accessibility and simplicity of notation, we state our main result as the following theorem (see Theorem 3.1 for a detailed description).
Theorem 1.1.Consider α > 1 2 , N ≥ 5 and a small enough constant
c 0 = c 0 (α) > 0. Let 0 < κ ≤ ν ≤ 1 40 (1 − 1 2α )6
5 , then we obtain Sobolev stability for initial data which is sufficiently small in Sobolev spaces, where the estimates qualitatively differ for the regimes κ ≳ ν 3 and κ ≲ ν 3 .More precisely:
• In the regime of ν 3 ≲ κ, for all initial data which satisfy
∥(v, b) in ∥ H N = ε ≤ c 0 ν 1 12 κ 1 2 , the global in time solution (v, b) of (2) satisfies the Lipschitz bound sup t>0 ∥(v, b)(t)∥ H N ≲ ε.
• In the regime of ν 3 ≳ κ, for all initial data which satisfy
∥(v, b) in ∥ H N = ε ≤ c 0 ν − 11 12 κ 5 6 , the global in time solution (v, b) of (2) satisfies the Lipschitz bound sup t>0 ∥(v, b)(t)∥ H N ≲ νκ − 1 3 ε.
In particular, we obtain Lipschitz stability for the Lipschitz constant L ≈ max(1, νκ − 1 3 ) for the smallness parameter ε 0 ≈ min(ν
1 12 κ 1 2 , ν − 11 12 κ 5 6
).
In the proof, we employ an energy method similar to [BBZD23, MZZ23, Zil21, Dol23, KZ23b].In the following, we outline the main challenges and novelties of the proof:
• The imbalance of resistivity κ and viscosity ν yields two cases ν 3 ≲ κ and ν 3 ≳ κ (or equivalently 1 ≲ νκ − 1 3 or 1 ≳ νκ − 1 3 ).These cases give different values for L, namely 1 and νκ − 1 3 .• We consider the case ν 3 ≳ κ.On certain time scales the viscosity is so strong that fluid effects get suppressed while the effects of the magnetic field dominate.Thus, the term ∂ t b = e 1 b 2 in (1) generates algebraic growth in specific regimes (see Subsection 2).Estimating this linear effect yields the norm inflation by L = νκ − 1 3 .The algebraic growth appears on different time scales depending on the frequency, a precise estimate of the nonlinear terms is necessary.
• For the case ν 3 ≲ κ the algebraic growth is bounded by a finite constant.
In the subcase ν = κ the sum of the threshold parameters is
γ 1 + γ 2 = 7 12
which is a slight improvement over 2 3 in [Dol23].
• In the proof of Theorem 1.1 we perform a low and high frequency decomposition a = a hi + a low .For high frequencies, the nonlinear term consist of a low ∇ t a hi , called transport term and a hi ∇ t a, called reaction term (including hi − hi interactions).Compared to the Navier-Stokes equation, in the case of the MHD equation, it is vital to bound the transport term precisely.In particular, for κ ≲ ν 3 the previously mentioned algebraic growth affects the estimate of the transport term strongly.• The threshold is determined by the nonlinear term v∇ t b = Λ −1 t ∇ ⊥ p 1 ∇b acting on b in (2), for the natural unknown p 1 = Λ −1 t ∇ ⊥ v (which we discuss later in more detail).In our estimates we rely on two stabilizing effects, the strong viscosity of v and the Λ −1 t in front of p 1 .For the nonlinear term v∇ t b both effects fall onto v. Due to the weaker integrability of the b this term determines the threshold after integrating in time.With the main challenges in mind, let us comment on the results:
• The size of the constant magnetic field α > 1 2 results in a strong interaction between v and b.Due to this interaction, the decay in v and growth in b are in balance (see Lemma 1).Constants may depend on α and degenerate as α ↓ 1 2 .For example we obtain lim α↓ 1 2 c 0 (α) = 0. • Figure 1 shows which areas stability has been proven.The graphic shows only qualitative behavior and after rescaling we obtain the same graphic.The resistivity κ is on the vertical axis and the viscosity ν is on the horizontal axis.We prove stability for the regime 0 < κ ≤ ν, which we divide into two segments: ν 3 ≲ κ in orange and ν 3 ≳ κ in red.In [Dol23] Dolce considered the regime of 0 < ( 16 α κ) 3 ≤ ν ≤ κ, which is in blue.The authors of [ZZ23] considered the line ν = 0 which is in purple.The black line corresponds to ν = κ > 0 of [Lis20].
Stability for the regimes 0 < ν ≤ ( 16 α κ) 3 , κ = 0 < ν and κ = ν = 0 remain open.For the set 0 < ν ≪ κ 3 , we expect that an adjusted application of the methods used in this article yield stability.We expect stability for the case κ = 0 and 0 < ν to be very difficult since we obtain linear growth for the p 2 variable.For Λ −1 t p 2 we obtain linear stability but then there is no time decay in the magnetic field and so we lack an important stabilizing effect.In the inviscid case, κ = ν = 0 the linearized system is stable in the p variables.However, due to the lack of dissipation, it is very challenging to bound the nonlinear terms.
• Our threshold consists of parameters γ 1 and γ 2 .An alternative notation is to impose the relation ν ≈ κ δ for some 0 ≤ δ ≤ 1.With that convention we obtain stability if ε ≤ c 0 κ γ(δ) for
γ = 1 2 + δ 12 δ ≥ 1 3 5 6 − 11
12 δ otherwise.The remainder of this article is structured as follows: • In Section 2 we discuss the linearized system.We identify two different time regions where "circular movement" or "strong viscosity" determine the linearized behavior.We estimate both effects separately and then establish the estimates for the linearized system.• In Section 3 we prove the main theorem.We employ a bootstrap approach, where we control errors in Proposition 3.1.The main difficulty is to bound the linear growth and the nonlinear effect of v∇ t b acting on b.
Notations and Conventions.For a, b ∈ R we denote their minimum and maximum as
min(a, b) = a ∧ b, max(a, b) = a ∨ b.
We write f ≲ g if f ≤ Cg for a constant C independent of ν and κ.Furthermore, we write f ≈ g if f ≲ g and g ≲ f .We denote the Lebesgue spaces L p = L p (T × R) and the Sobolev spaces
H N = H N (T × R) for some N ∈ N.
For time-dependent functions, we denote L p H s = L p t H s as the space with the norm
∥f ∥ L p H s = ∥f ∥ H s (T×R) L p (0,T ) , (3)
where omit writing the T .We write the time-dependent spatial derivatives
∂ t y = ∂ y − t∂ x , ∇ t = (∂ x , ∂ t y ) T , ∆ t = ∂ 2
x + (∂ t y ) 2 , and the half Laplacians as
Λ = (−∆) 1 2 , Λ t = (−∆ t ) 1 2 .
The function f ∈ H N is decomposed into its x average and the orthogonal complement
f = (y) = f (x, y)dx, f ̸ = = f − f = .
The adapted unknowns.For the following, it is useful to change to the unknowns
p 1,̸ = = Λ −1 t ∇ ⊥ t v ̸ = and p 2,̸ = = Λ −1 t ∇ ⊥ t b ̸ = . However, since Λ −1 t ∇ ⊥ t
is not a bounded operator on the x average, we define
p 1,̸ = = Λ −1 t ∇ ⊥ t v ̸ = , p 1,= = v 1,= , p 2,̸ = = Λ −1 t ∇ ⊥ t b ̸ = , p 2,= = b 1,= .
Thus (2) can be equivalently expressed as
∂ t p 1 − ∂ x ∂ t y ∆ −1 t p 1 − α∂ x p 2 = ν∆ t p 1 + Λ −1 t ∇ ⊥ t (b∇ t b − v∇ t v), ∂ t p 2 + ∂ x ∂ t y ∆ −1 t p 2 − α∂ x p 1 = κ∆ t p 2 + Λ −1 t ∇ ⊥ t (b∇ t v − v∇ t b), p| t=0 = p in . (4)
These unknowns are particularly useful since
∥Ap 1 ∥ L 2 = ∥Av∥ L 2 , ∥Ap 2 ∥ L 2 = ∥Ab∥ L 2 ,
for all Fourier multipliers A such that one side is finite.
Linear Stability
In this section, we consider the behavior of the linearized version of (4):
∂ t p 1 − ∂ x ∂ t y ∆ −1 t p 1 − α∂ x p 2 = ν∆ t p 1 , ∂ t p 2 + ∂ x ∂ t y ∆ −1 t p 2 − α∂ x p 1 = κ∆ t p 2 .
(5)
For this equation, we establish the following proposition:
Proposition 1.Consider α > 1 2 and 0 < κ ≤ ν.Let p in ∈ H N with p in,= = p in dx = 0, then the solution p of (5) satisfies the bound
∥p(t)∥ H N ≲ e −cκ 1 3 t (1 + κ − 1 3 ν)∥p in ∥ H N . (6)
For the proof of Proposition 1, we perform a Fourier transform (x, y) → (k, ξ) and replace p 1 by ip 1 (5) to infer for modes k ̸ = 0
∂ t p 1 = − t− ξ k 1+(t− ξ k ) 2 p 1 − αkp 2 − νk 2 (1 + (t − ξ k ) 2 )p 1 , ∂ t p 2 = t− ξ k 1+(t− ξ k ) 2 p 2 + αkp 1 − κk 2 (1 + (t − ξ k ) 2 )p 2 . (7)
Where with slight abuse of notation we omit writing the Fourier transformation.This equation has several effects that appear on different regimes of t − ξ k , which we discuss in the following.The effect of circular movement appears on |t − ξ k | ≲ ν −1 .We first sketch these effects Circular movement.To highlight the effect of the constant magnetic field α in (5) we consider the toy model
∂ t p 1 = −αkp 2 , ∂ t p 2 = αkp 1 . (8)
This is solved by
p(t) = cos(αt) − sin(αkt) sin(αt) cos(αkt) p in .
We call this effect of the constant magnetic field (8) circular movement, which leads to a transfer between p 1 and p 2 .This circular movement is counteracted by viscosity for times away from ξ k .Effect of strong viscosity.Let us consider the case when 0 < κ ≪ ν and for simplicity of notation let k = 1 and ξ = 0. Due to the viscosity, we obtain p 1 ≈ 0 for large times t ≥ t 0 ≫ 1.Then from (7) we deduce the toy model
∂ t p 2 = ( t 1+t 2 − κ(1 + t 2 ))p 2 . (9)
The first term in (9) leads to linear growth until the resistivity is strong enough for the second term to take over.This is seen in the explicit solution of (9)
p 2 (t) = ⟨t⟩ ⟨t 0 ⟩ exp(−κ t t 0 1 + ((τ − t)) 2 dτ )p 2 (t 0 ).
This is estimated by
p 2 (t) ≲ t −1 0 κ − 1 3 e −cκ 1 3 (t−t 0 ) p 2 (t 0 ),
which corresponds to the maximal growth which we obtain.In the following, we will see that t 0 ≈ ν −1 is the time after which viscosity dominates.The reader may expect that the enhanced dissipation timescale ν − 1 3 would be the relevant timescale, but the combination of circular movement and the viscosity gives enough decay for p 2 such that the linear growth gets suppressed until the time ν −1 .
Proof of Proposition 1.
Proof.For simplicity of notation, we introduce the new variable s = t − ξ k and initial time
s in = − ξ k . Then equation (7) reads ∂ s p 1 = − s 1+s 2 p 1 − αkp 2 − νk 2 (1 + s 2 )p 1 , ∂ s p 2 = s 1+s 2 p 2 + αkp 1 − κk 2 (1 + s 2 )p 2 . Further we change the unknown to p = exp(− κ 2 k 2 (s − s in + 1 3 (s 3 − s 3 in )))p. For κ = κ 2 and ν = ν − κ 2 , this yield the equation ∂ s p1 = − s 1+s 2 p1 − αk p2 − νk 2 (1 + s 2 )p 1 , ∂ s p2 = s 1+s 2 p2 + αk p1 − κk 2 (1 + s 2 )p 1 .
Let us denote s 0 := ν −1 and in the following, we distinguish between times |s| ≤ s 0 and |s| ≥ s 0 .We first consider the case s in ≤ −s 0 .For |s| ≤ s 0 , the circular movement is not suppressed by the viscosity.
We define the energy E = |p| 2 + 1 αk 2s 1+s 2 p1 p2 , then E is a positive quadratic form due to our assumption α > 1 2 and satisfies (1
− 1 2αk )|p| 2 ≤ E ≤ (1 + 1 2αk )|p| 2 .
We calculate the time derivative
∂ s E + νk 2 (1 + s 2 )p 2 1 + κk 2 (1 + s 2 )p 2 2 = 1 αk ∂ s ( 2s 1+s 2 )p 1 p2 − 2s (ν−κ)k α p1 p2 ≤ 1 αk ∂ s ( 2s 1+s 2 )p 1 p2 + 1 2 νk 2 (1 + s 2 )p 2 1 + 2ν α 2 p2 2 and so with |p| 2 ≤ 2α 2α−1 E we infer |∂ s E| ≤ α α− 1 2 ( 1 1+s 2 + 2 ν α 2 )E. Gronwall's lemma implies E(s 0 ) ≤ exp α α− 1 2 (π + 2 ν α 2 |s 0 |)r E(−s 0 ). Since νs 0 = 1, we deduce E(s 0 ) ≲ E(−s 0 ) and thus |p(s 0 )| ≲ |p(−s 0 )|. (10) Consider the case |s| ≥ s 0 , we calculate 1 2 ∂ s |p| 2 ≤ (− s 1+s 2 − νk 2 (1 + s 2 ))p 2 1 + ( s 1+s 2 − κk 2 (1 + s 2 ))p 2 2 , and since (− s 1+s 2 − νk 2 (1 + s 2 )) ≤ 0 for all |s| ≥ s 0 we conclude ∂ s |p| 2 ≤ ( 2s 1+s 2 − κk 2 (1 + s 2 )) + p2 2 . Thus we obtain the estimate |p(s)| 2 ≤ |p(s in )| 2 s ≤ −s 0 , 1+s 2 1+s 2 0 |p(s 0 )| 2 s 0 ≤ s ≤ 2(κk 2 ) − 1 3 , (1 + 4ν 2 κ − 2 3 k − 4 3 )|p(s 0 )| 2 s 0 ∨ 2(κk 2 ) − 1 3 ≤ s. Combining this with (10) we infer |p(s)| ≲ (1 + νκ − 1 3 k − 2 3 )|p(s in )|.
The case s in ≥ −s 0 is established similarly since we only bound the growth.With
exp(− κ 2 k 2 (s − s in + 1 3 (s 3 − s 3 in ))) ≲ e −cκ 1 3 t we deduce |p(s)| ≲ e −cκ 1 3 t |p|(s) ≲ (1 + νκ − 1 3 k − 2 3 )e −cκ 1 3 t |p|(s in ).
Equation (7) decouples in ξ and k, so we infer the proposition with this estimate.□
Sobolev Stability for the Nonlinear System
The following theorem is a more general statement of Theorem 1.1.We dedicate the remainder of the section to the proof.Theorem 3.1.Let α > 1 2 and N ≥ 5, then there exist c 0 , c > 0, such that for all
0 < κ ≤ ν ≤ 1 40 (1 − 1 2α ) 6 5 there exist L = max(1, νκ − 1 3
), such that for all initial data, which satisfy
∥(v, b) in,̸ = ∥ H N = ε ≤ c 0 L −1 ν 1 12 κ 1 2 , ∥(v, b) in,= ∥ H N ≤ ε, with ε ≤ ε ≤ ν − 1 12 ε (11)
the corresponding solution of (2) satisfies the bound
∥(v, b) ̸ = (t)∥ L ∞ H N + ∥∇ t (νv, κb) ̸ = ∥ L 2 H N ≲ Le −cκ 1 3 t ε, ∥(v, b) = (t)∥ L ∞ H N + ∥∂ y (νv, κb) = ∥ L 2 H N ≲ ε. (12)
Furthermore, we obtain the following enhanced dissipation estimates
∥v ̸ = ∥ L 2 H N ≲ Lν − 1 6 e −cκ 1 3 t ε, ∥b ̸ = ∥ L 2 H N ≲ Lκ − 1 6 e −cκ 1 3 t ε.
This theorem implies Theorem 1.1.With slight abuse of notation, we write L as the ν and κ dependent part of the Lipschitz constant.We prove this theorem by using a bootstrap method.Let A be the Fourier weight
A : = M |∇| N e cκ 1 3 t1 ̸ = , where M = M L M 1 M κ M ν M ν 3 are defined as − ṀL M L = t− ξ k 1+( ξ k −t) 2 1 {ν −1 ≤t− ξ k ≤(c 1 κk 2 ) − 1 3 } k ̸ = 0, − Ṁ1 M 1 = C α |k|+ν 1 12 |k| 2 k 2 +(ξ−kt) 2 k ̸ = 0, − Ṁν Mν = ν 1 3 1+ν 2 3 (t− ξ k ) 2 k ̸ = 0, − Ṁκ Mκ = κ 1 3 1+κ 2 3 (t− ξ k ) 2 k ̸ = 0, − Ṁν 3 M ν 3 = Cαν 1+ν 2 (t− ξ k ) 2 k ̸ = 0, M • (t = 0) = M • (k = 0) = 1.
The weight M L is an adaption of the weight m 1 2 in [Lis20] to our setting.The method of using time-dependent Fourier weights is common when working with solutions around Couette flow and the other weights are modifications of previously used weights (cf.[BVW18, MZ22, Lis20, ZZ23]).For simplicity, here we only state their main properties and refer to Appendix A for a detailed description.The constants
C α = 2 min(1,α− 1 2 ) , c = 1 200 (1 − 1 2α ) 2 and c 1 = 1 20 (1 − 1 2α
) are determined through the linear estimates.For the weights we obtain
L −1 ≤ min(1, ν −1 κ 1 3 k 2 3 ) ≲ M L ≤ 1, M 1 ≈ M κ ≈ M ν ≈ M ν 3 ≈ 1. (13)
We note that the weight M L is distinct from the others due to its lower bound L −1 , which depends on ν and κ.The weight M L is necessary to bound the linear growth in the region ν −1 ≲ t − ξ k ≲ (κk 2 ) − 1 3 .Controlling the effects of M L is one of the main challenges in the proof of Theorem 3.1.We recall the unknowns p and equation (4)
∂ t p 1 − ∂ x ∂ t y ∆ −1 t p 1 − α∂ x p 2 = ν∆ t p 1 + Λ −1 t ∇ ⊥ t (b∇ t b − v∇ t v), ∂ t p 2 + ∂ x ∂ t y ∆ −1 t p 2 − α∂ x p 1 = κ∆ t p 2 + Λ −1 t ∇ ⊥ t (b∇ t v − v∇ t b), p| t=0 = p in . (14) Let χ ∈ C ∞ (R + × Z × R) be a Fourier multiplier defined by χ = χ(k, ξ) = 1 |t − ξ k | ≤ ν −1 0 |t − ξ k | ≥ 2ν −1 (15) ∂ t χ ≤ 2ν. (16)
We define the main energy
E : = ∥Ap ̸ = ∥ 2 L 2 + 2 α ⟨∂ t y ∆ −1 t χAp 1,̸ = , Ap 2,̸ = ⟩.
As α > 1 2 , this energy is positive definite and satisfies
(1 − 1 2α )∥Ap∥ L 2 ≤ E ≤ (1 + 1 2α )∥Ap∥ L 2 . (17)
In the following, we assume initial data as in Theorem 3.1, i.e. (11).We use a bootstrap approach to prove the following two estimates globally in time:
The energy estimate without x-average
∥E∥ L ∞ + ∥A∇ t ⊗ (νp 1,̸ = , κp 2,̸ = )∥ 2 L 2 L 2 + j=1,ν,κ,ν 3 ∥ − Ṁj M j Ap ̸ = ∥ 2 L 2 L 2 ≤ (Cε) 2(18)
The energy estimate with x-average
∥p = ∥ 2 L ∞ H N + ∥∂ y (νp 1,= , κp 2,= )∥ 2 L 2 H N ≤ (C ε) 2 . (19)
We then prove that the equality in the estimates is not attained at time T .By local wellposedness, the estimates thus remain valid at least for a short additional time.This contradicts the maximality and thus T has to be infinite.We note that we suppress in our notation the T in the estimates (see
(3)). With 1 ≤ κ − 1 3 ( − Ṁκ Mκ + κk 2 (1 + (t − ξ k ) 2 ) and 1 ≤ ν − 1 3 ( − Ṁν Mν + νk 2 (1 + (t − ξ k ) 2
)) we infer from (17) and (18) the enhanced dissipation estimates
∥Ap 1,̸ = ∥ L 2 L 2 ≤ 2(1 − 1 2α ) −1 ν − 1 6 Cε, (20)∥Ap 2,̸ = ∥ L 2 L 2 ≤ 2(1 − 1 2α ) −1 κ − 1 6 Cε. (21)
By the construction of M 1 we obtain
∥∂ x Λ −1 t Ap∥ L 2 ≲ ν − 1 12 ε.
We obtain the energy estimate by deriving the energy
E ∂ t E + 2∥A∇ t ⊗ (νp 1,̸ = , κp 2,̸ = )∥ 2 L 2 + 2∥ − Ṁ M Ap ̸ = ∥ 2 L 2 =2cκ 1 3 ∥Ap ̸ = ∥ 2 L 2 − 2⟨A(1 − χ)p 1,̸ = , ∂ x ∂ t x ∆ −1 t Ap 1,̸ = ⟩ + 2⟨A(1 − χ)p 2,̸ = , ∂ x ∂ t x ∆ −1 t Ap 2,̸ = ⟩ + 4 α ⟨χ∂ t y ∆ −1 t Ap 1,̸ = , Ȧp 2,̸ = ⟩ + 2 α ⟨χ∂ t (∂ t y ∆ −1 t )Ap 1,̸ = , Ap 2,̸ = ⟩ + 2 α ⟨∂ t (χ)∂ t y ∆ −1 t Ap 1,̸ = , Ap 2,̸ = ⟩ + 2|ν+κ| α ⟨χ∂ t y Ap 1,̸ = , Ap 2,̸ = ⟩ + 2⟨Av ̸ = , A(b∇ t b − v∇ t v)⟩ + 2⟨Ab ̸ = , A(b∇ t v − v∇ t b)⟩ + 2 α ⟨χA∂ t y ∆ −1 t b ̸ = , A(b∇ t b − v∇ t v)⟩ + 2 α ⟨χA∂ t y ∆ −1 t v ̸ = , A(b∇ t v − v∇ t b)⟩ =L 1 + L N R + L R + N L ̸ = + ON L. (22)
Where we denoted by ON L all the terms which include the operator ∂ t y ∆ −1 t and N L the one which does not.Furthermore, for the energy of x-averages, we obtain
∂ t ∥p = ∥ H N + ∥∂ y (νp 1,= , κp 2,= )∥ H N ≤ ⟨⟨∂ y ⟩ N v 1,= , ⟨∂ y ⟩ N (b∇ t b − v∇ t v) = ⟩ + ⟨⟨∂ y ⟩ N b 1,= , ⟨∂ y ⟩ N (b∇ t v − b∇ t v) = ⟩ = N L = .
(23)
In the following subsections, we establish the following proposition: Proposition 3.1 (Control of errors).Under the assumptions of Theorem 3.1, there exists a constant C = C(α) > 0 such that if (18) and (19) are satisfied for T > 0, then the following estimate holds
T 0 L 1 + L R + L N R dt ≤ 17+ 3 2 α 10 (Cε) 2 + 2∥ − ṀL M L Ap 2 ∥ 2 L 2 L 2 , T 0 N L ̸ = + ON L dt ≲ Lν − 1 12 κ − 1 2 ε 3 + (Lκ − 1 3 + κ − 1 2 )εε 2 , T 0 N L = dt ≲ Lν − 1 12 κ − 1 2 εε 2 . (24)
With this proposition we deduce Theorem 3.1:
Proof of Theorem 3.1.By a standard application of the Banach fixed-point theorem we obtain local well-posedness, see Appendix B. Thus for all initial data, there exists a time interval [0, T ] such that (18) and ( 19) hold.Let T * be the maximal time such that (18) and ( 19) hold.Let c 0 be a given, small constant and suppose for the sake of contradiction that T * < ∞.With the estimates ( 22), ( 23) and ( 24) and since c 0 is small we obtain that the estimates (18) and ( 19) do not attain equality.Thus by local existence, T * is not the maximal time and thus we obtain a contradiction.Therefore, for small enough c 0 , (18) and ( 19) hold global in time and so we infer Theorem 3.1.□
The remainder of the section is dedicated to the proof of Proposition 3.1.We rearrange and use partial integration to infer that
⟨Av ̸ = , b∇ t Ab ̸ = − v∇ t Av ̸ = ⟩ + ⟨Ab ̸ = , b∇ t Av ̸ = − v∇ t Ab ̸ = ⟩ = ⟨b, ∇ t (Av ̸ = Ab ̸ = )⟩ − 1 2 ⟨v, ∇ t (Av ̸ = Av ̸ = ) + ∇ t (Ab ̸ = Ab ̸ = )⟩ = 0. (25)
The N L term consists of trilinear products with the unknowns a 1 a 2 a 3 ∈ {vvv, vbb, bbv, bvb}.(26) Thus, we denote the nonlinear terms
N L ̸ = [a 1 a 2 a 3 ] =⟨Aa 1 ̸ = , A(a 2 ̸ = ∇ t a 3 ̸ = ) ̸ = − a 2 ̸ = ∇ t Aa 3 ̸ = ⟩, + ⟨Aa 1 ̸ = , A(a 2 = ∇ t a 3 ̸ = ) − a 2 = ∇ t a 3 ̸ = ⟩, + ⟨Aa 1 ̸ = , A(a 2 ̸ = ∇ t a 3 = )⟩, N L = [a 1 a 2 a 3 ] =⟨⟨∂ y ⟩ N a 1 = , ⟨∂ y ⟩ N (a 2 ̸ = ∇ t a 3 ̸ = ) = ⟩.
If we do not use specific choices for a 1 a 2 a 3 we write just N L. Similarly, we use a 1 a 2 a 3 ∈ {bvv, bbb, vbv, vvb} for ON L. Furthermore, we always use i such that p i = Λ −1 t ∇ ⊥ t a 2 in the sense that i = 1 if a 2 = v and i = 2 if a 2 = b.We perform the energy estimates in the next subsections:
• In Subsection 3.1 we estimate the linear error terms.In this subsection, the split with χ into resonant and non-resonant regions depending on ν is vital.• In Subsection 3.2 we conclude the energy estimate for the nonlinear term without x average.Here it is necessary to perform a low and high frequency decomposition.This gives us a reaction and a transport term.In particular, for κ ↓ 0 bounding the transport term is very challenging due to the linear growth.• In Subsections 3.3, 3.4 and 3.5 we estimate nonlinear terms with an x-average component.• In Subsection 3.6 we estimate nonlinear term which arise due χ in the resonant regions.For these terms, we obtain an additional Λ −1 t , which has a stabilizing effect.This stabilizing effect is necessary due to a nonlinear term consisting of only magnetic components.
3.1.Linear estimates.In this section, we establish estimates of the linear errors L 1 , L R and L N R of (22).In order to estimate L 1 , we use (20) and (21) to deduce
L 1 dτ = 2cκ 1 3 ∥Ap ̸ = ∥ 2 L 2 L 2 ≤ 8(1 − 1 2α ) −1 c(Cε) 2 .
For the L N R terms in (22), we infer
⟨A(1 − χ)p 1,̸ = , A∂ x ∂ t x ∆ −1 t p 1,̸ = ⟩ = k̸ =0 dξ(1 − χ) t− ξ k 1+(t− ξ k ) 2 A 2 p 2 1 ≤ ν 3 ∥A∇ t p 1,̸ = ∥ 2 L 2 , since (1 − χ) t− ξ k 1+(t− ξ k ) 2 ≤ (1 − χ)(ν) 3 (1 + (t − ξ k ) 2 ) due to χ = 1 for |t − ξ k | ≤ ν −1 . Furthermore, using (31) we estimate ⟨A(1 − χ)p 2,̸ = , A∂ x ∂ t x ∆ −1 t p 2 ⟩ = k̸ =0 dξ(1 − χ) t− ξ k 1+(t− ξ k ) 2 A 2 p 2 2 ≤ k̸ =0 dξ(1 − χ)( − ṀL M L + κc 1 (1 + (t − ξ k ) 2 ))A 2 p 2 2 ≤ ∥ − ṀL M L Ap 2,̸ = ∥ 2 L 2 + κc 1 ∥∇ t Ap 2,̸ = ∥ 2 L 2 .
Thus with (18) we deduce
L N R dτ ≤ (2ν 2 + 2c 1 )(Cε) 2 + 2∥ − ṀL M L Ap 2,̸ = ∥ 2 L 2 L 2 .
For L R , we estimate in frequency space
|(1 ̸ = ∂ t y ∆ −1 t ) ∧ | = |( ξ−kt k 2 +(ξ−kt) 2 ) k̸ =0 | ≤ 1 2 , − ṀL M L |(∂ t y ∆ t ) ∧ | ≤ (t− ξ k ) 2 k(1+(t− ξ k ) 2 ) 2 k̸ =0 ≤ C −1 α − Ṁ1 M 1 .
So it follows that
4 α ⟨χ∂ t y ∆ −1 t Ap 1,̸ = , Ȧp 2,̸ = ⟩ = 4 α ⟨χAp 1,̸ = , (cκ 1 3 + Ṁ1 M 1 + ṀL M L + Ṁκ Mκ + Ṁν Mν + Ṁν 3 M ν 3 )∂ t y ∆ −1 t Ap 2,̸ = ⟩ ≤ 2c α κ 1 3 ∥Ap ̸ = ∥ 2 L 2 + (1 + C −1 α ) 1 α ∥ − Ṁ1 M 1 Ap ̸ = ∥ 2 L 2 + 1 α ∥ − Ṁκ Mκ Ap ̸ = ∥ 2 L 2 + 1 α ∥ − Ṁν Mν Ap ̸ = ∥ 2 L 2 + 1 α ∥ − Ṁν 3 M ν 3 Ap ̸ = ∥ 2 L 2 .
We use the estimate in frequency space
|(((∂ 2 x − (∂ t y ) 2 )∆ −2 t ) ̸ = ) ∧ | = 1−(t− ξ k ) 2 k 2 (1+(t− ξ k ) 2 ) 2 k̸ =0 ≤ C −1 α − Ṁ1 M 1 , to infer that 1 α ⟨χAp 1,̸ = , A∂ −1 x (∂ 2 x − (∂ t y ) 2 )∆ −2 t p 2,̸ = ⟩ ≤ C −1 α 1 α ∥ − Ṁ1 M 1 Ap 1,̸ = ∥ L 2 ∥ − Ṁ1 M 1 Ap 2,̸ = ∥ L 2 ≤ C −1 α 1 2α ∥ − Ṁ1 M 1 Ap ̸ = ∥ 2 L 2 . With (16) we deduce ⟨∂ t y ∆ −1 t ∂ t (χ)Ap 1,̸ = , Ap 2,̸ = ⟩ ≤ ν∥Ap 1,̸ = ∥ L 2 ∥AΛ −1 t p 2,̸ = ∥ L 2 .
By the Fourier support of χ (see ( 15)) and the definition of
M ν 3 we obtain χ ≤ 2C −1 α ν −1 − Ṁν 3 M ν 3 χ, which yields |ν+κ| α ⟨χA∂ t y p 1,̸ = , Ap 2,̸ = ⟩ ≤ 2C −1 α ν 1 2 α ∥A∂ t y p 1,̸ = ∥ L 2 ∥ −M ν 3 M ν 3 Ap 2,̸ = ∥ L 2 . Thus for the linear error L R we infer L R dτ ≤ ( 2c α + ν 5 6 )(Cε) 2 + 1+C −1 α α ∥ − Ṁ1 M 1 p ̸ = ∥ 2 L 2 L 2 + 1 α ∥ − Ṁκ Mκ p ̸ = ∥ 2 L 2 L 2 + 1 α ∥ − Ṁν Mν p ̸ = ∥ 2 L 2 L 2 + 1+C −1 α 2α ∥ − Ṁν 3 M ν 3 Ap 2,̸ = ∥ L 2 L 2 + C −1 α 1 2α ν∥A∂ t y p 1,̸ = ∥ 2 L 2 L 2 .
Combining the estimates for all linear terms, we obtain
L + L R + L N R dτ ≤ ((8 + 2 α )(1 − 1 2α ) −1 c + 2ν 2 + 2c 1 + ν 5 6 )(Cε) 2 + 2∥ − ṀL M L Ap 2 ∥ 2 L 2 L 2 + (1 + 3 2 C −1 α ) 1 α ∥χ − Ṁ1 M 1 p ̸ = ∥ 2 L 2 L 2 + 1 α ∥ − Ṁκ Mκ p ̸ = ∥ 2 L 2 L 2 + 1 α ∥ − Ṁν Mν p ̸ = ∥ 2 L 2 L 2 + 1+C −1 α 2α ∥ −M ν 3 M ν 3 Ap 2,̸ = ∥ L 2 L 2 + C −1 α 1 2α ν∥A∂ t y p 1,̸ = ∥ 2 L 2 L 2 ≤ (12(1 − 1 2α ) −1 c + 2ν 2 + 2c 1 + ν 5 6 + 1+2C −1 α 2α )(Cε) 2 + 2∥ − ṀL M L Ap 2,̸ = ∥ 2 L 2 L 2 . Since α > 1 2 we deduce 1+2C −1 α α < 1 + 1 2α . Choosing the constants such that c = 1 200 (1 − 1 2α ) 2 , c 1 = 1 20 (1 − 1 2α
), and recalling that
ν ≤ 1 40 (1 − 1 2α ) 6 5 , we conclude that (12(1 − 1 2α ) −1 c + 2ν 2 + 2c 1 + ν 5 6 + 1+2C −1 α 2α < 17+ 3 2α
20 .Thus we obtain the estimate
L 1 + L R + L N R dτ ≤ 17+ 3 2α 20 (Cε) 2 + 2∥ − ṀL M L Ap 2,̸ = ∥ 2 L 2 L 2 .
This yields the first estimate of Proposition 3.1.
3.2.Nonlinear terms without an x-average.We apply the notation of ( 26) and aim to estimate terms of the form
⟨Aa 1 ̸ = , A(a 2 ̸ = ∇ t a 3 ̸ = ) − a 2 ̸ = ∇ t Aa 3 ̸ = ⟩ = k,l,k−l̸ =0 d(ξ, η) A(k,ξ)−A(l,η) A(k−l,ξ−η)A(l,η) ξl−kη ((k−l) 2 +(ξ−η−(k−l)t) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) = T + R.
Here, we split the integral into the reaction R and the transport T terms which correspond to the sets
Ω R = {|k − l, ξ − η| ≥ 1 8 |l, η|}, Ω T = {|k − l, ξ − η| < 1
8 |l, η|}, in Fourier space.We split the weights
A(k, ξ) − A(l, η) = e ctκ 1 3 (M L (k, ξ) − M L (l, η))M 1 (k, ξ)M κ (k, ξ)M ν (k, ξ)M ν 3 (k, ξ)|k, ξ| N + e ctκ 1 3 (|k, ξ| N − |l, η| N )M L (l, η)M 1 (k, ξ)M κ (k, ξ)M ν (k, ξ)M ν 3 (k, ξ) + e ctκ 1 3 (M 1 (k, ξ) − M 1 (l, η))M L (l, η)M κ (k, ξ)M ν (k, ξ)M ν 3 (k, ξ)|l, η| N + e ctκ 1 3 (M κ (k, ξ) − M κ (l, η))M 1 (l, η)M L (l, η)M ν (k, ξ)M ν 3 (k, ξ)|l, η| N + e ctκ 1 3 (M ν (k, ξ) − M ν (l, η))M 1 (l, η)M L (l, η)M κ (l, η)M ν 3 (k, ξ)|l, η| N + e ctκ 1 3 (M ν 3 (k, ξ) − M ν 3 (l, η))M 1 (l, η)M L (l, η)M κ (l, η)M ν (l, η)|l, η| N
and thus by (13) we estimate
A(k,ξ)−A(l,η) A(k−l,ξ−η)A(l,η) ≲ e −ctκ 1 3 |M L (k,ξ)−M L (l,η)| M L (k−l,ξ−η)M L (l,η) |ξ,η| N |l,η| N |k−l,ξ−η| N + e −ctκ 1 3 ||k,ξ| N −|l,η| N | |l,η| N |k−l,ξ−η| N 1 M L (k−l,ξ−η) + e −ctκ 1 3 j=1,κ,ν,ν 3 |M j (k, ξ) − M j (l, η)| 1 |k−l,ξ−η| N 1 M L (k−l,ξ−η) . (27)
Based on this estimate, in the following we distinguish between different regimes in frequency,
T = k,l,k−l̸ =0 d(ξ, η)1 Ω T A(k,ξ)−A(l,η) A(k−l,ξ−η)A(l,η) ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 M L (l,η) ( 1 |l| + ν 1 12 ) 1 |k−l,ξ−η| N −1 ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) + k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 | η l −t|≥| ξ−η k−l −t| j=κ,ν,ν 3 |M j (k,ξ)−M j (l,η)| M L (l,η) 1 |k−l,ξ−η| N ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) + k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 | η l −t|≤| ξ−η k−l −t| j=κ,ν,ν 3 |M j (k,ξ)−M j (l,η)| M L (l,η) 1 |k−l,ξ−η| N ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) + k,l,k−l̸ =0 d(ξ, η)1 Ω T M L (k,ξ)−M L (l,η) M L (k−l,ξ−η)M L (l,η) 1 |k−l,ξ−η| N ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) = T 1,1 + T 1,2 + T 1,3 + T 2 .
Here, the T 1,1 term is due to estimate (28).For (29) we distinguish between the frequencies 13) and (34) to estimate
| η l − t| ≥ | ξ−η k−l − t| in T 1,2 and | η l − t| ≤ | ξ−η k−l − t| in T 1,3 . The M L commutator (30) is T 2 , which requires further splitting. For T 1,1 we use ξl − kη = (ξ − η − (k − l)t)l − (k − l)(η − lt), (T 1,1 = k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 M L (l,η) ( 1 |l| + ν 1 12 ) 1 |k−l,ξ−η| N −1 ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ ∥Aa 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥ 1 M L Aa 3 ̸ = ∥ L 2 + ∥Aa 1 ̸ = ∥ L 2 ∥AΛ −1 t p i,̸ = ∥ L 2 ∥ 1 M L A∂ t y a 3 ̸ = ∥ L 2 + ν 1 12 ∥Aa 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥ 1 M L A∂ x a 3 ̸ = ∥ L 2 ≤ L∥Aa 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥Aa 3 ̸ = ∥ L 2 + L∥Aa 1 ̸ = ∥ L 2 ∥AΛ −1 t p i,̸ = ∥ L 2 ∥A∂ t y a 3 ̸ = ∥ L 2 + ν 1 12 ∥Aa 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥Λ t a 3 ̸ = ∥ L 2 . After integrating in time we deduce that T 1,1 dτ ≲ (L + ν − 1 12 )κ − 1 2 ε 3 . For T 1,2 we use | η l − t| ≥ | ξ−η k−l − t| to infer that |ξl − kη| = |(ξ − η − (k − l)t)l − (k − l)(η − lt)| ≤ 2|(k − l)(η − lt)|. Furthermore, with i=ν,κ,ν 3 |M i (k, ξ) − M i (l, η)| ≈ 1 and (32) we conclude that T 1,2 ≲ k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 | η l −t|≥| ξ−η k−l −t| 1 M L (l,η) 1 |k−l,ξ−η| N |(k−l)(η−lt)| ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ ∥Aa 1 ̸ = ∥ L 2 ∥AΛ −1 t p i,̸ = ∥ L 2 ∥ 1 M L A∂ t y a 3 ̸ = ∥ L 2 ≲ L∥Aa 1 ̸ = ∥ L 2 ∥AΛ −1 t p i,̸ = ∥ L 2 ∥A∂ t y a 3 ̸ = ∥ L 2 . So after integrating in time, we obtain T 1,2 dτ ≲ Lκ − 1 2 ε 3 . For T 1,3 , we use | η l −t| ≤ | ξ−η k−l −t| to infer ξl −kη ≤ 2(ξ −η −(k −l)t)l. Furthermore, with (40) we deduce j=κ,ν,ν 3 |M j (k, ξ) − M j (l, η)| ≲ ν 1 3 |ξl−kη| |kl| .
Combining these two estimates by Hölder's inequality and (32) it follows, that
T 1,3 ≲ k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 | η l −t|≤| ξ−η k−l −t| 1 M L (l,η) 1 |k−l,ξ−η| N ν 1 3 (ξl−kη) 2 kl((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 | η l −t|≤| ξ−η k−l −t| 1 M L (l,η) 1 |k−l,ξ−η| N ν 1 3 (ξ−η−(k−l)t) 2 l 2 kl((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ ν 1 3 k,l,k−l̸ =0 d(ξ, η)1 Ω T 1 | η l −t|≤| ξ−η k−l −t| 1 M L (l,η) |ξ−η−(k−l)t| |k−l,ξ−η| N −1 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ ν 1 3 ∥Aa 1 ̸ = ∥ L 2 ∥AΛ t p i,̸ = ∥ L 2 ∥ 1 M L Aa 3 ̸ = ∥ L 2 ≲ Lν 1 3 ∥Aa 1 ̸ = ∥ L 2 ∥AΛ t p i,̸ = ∥ L 2 ∥Aa 3 ̸ = ∥ L 2 .
Thus integrating in time yields
T 1,3 dτ ≤ Lν 1 6 κ − 1 2 ε 3 .
To estimate the T 2 term, we split the integral into the sets
Ω 1 = {min(t − η l , t − ξ−η k−l ) ≥ ν −1 }, Ω 2 = {t − η l ≥ ν −1 ≥ t − ξ−η k−l }, Ω 3 = {t − ξ−η k−l ≥ ν −1 ≥ t − η l }, Ω 4 = {t − ξ k ≥ ν −1 ≥ max(t − η l , t − ξ−η k−l )}.
For frequencies such that ν −1 ≥ max(t − η l , t − ξ k ), then M L (k, ξ) − M L (l, η) = 0 and hence the commutator vanishes.Thus the sets Ω j covers all regions of the support.The sets Ω 1 , Ω 2 and Ω 3 are chosen to distinguish between 1 M L = 1 and 1 M L > 1 for different frequencies and on set Ω 4 we use strong dissipation in the first component.We split the set T 2 into
T 2 = k,l,k−l̸ =0 d(ξ, η)1 Ω T M L (k,ξ)−M L (l,η) M L (k−l,ξ−η)M L (l,η) ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 1 |k−l,ξ−η| N (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η)(1 Ω 1 + 1 Ω 2 + 1 Ω 3 + 1 Ω 4 ) = T 2,1 + T 2,2 + T 2,3 + T 2,4 .
For T 2,1 we use (32) to deduce
T 2,1 ≤ ν 2 k,l,k−l̸ =0 d(ξ, η)1 Ω 1 ⟨t − η l ∧ κ − 1 3 ⟩⟨t − ξ−η k−l ∧ κ − 1 3 ⟩ 1 |k−l,ξ−η| N −1 (ξ−η−(k−l)t)l−(k−l)(η−lt) ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ ν 2 ∥Aa 1 ̸ = ∥ L 2 ∥(Λ t ∧ κ − 1 3 )Ap i,̸ = ∥ L 2 ∥AΛ t a 3 ̸ = ∥ L 2 + Lν∥Aa 1 ̸ = ∥ L 2 ∥(Λ t ∧ κ − 1 3 )Λ −1 t Λ −1 Ap i,̸ = ∥ L 2 ∥A∂ t y a 3 ̸ = ∥ L 2 and so T 2,1 dτ ≲ Lν 5 6 κ − 1 2 ε 3 .
Now we consider T 2,2 .By (32) we infer
T 2,2 ≤ k,l,k−l̸ =0 d(ξ, η)1 Ω 2 ν⟨t − η l ∧ κ − 1 3 ⟩ 1 |k−l,ξ−η| N −1 (ξ−η−(k−l)t)l−(k−l)(η−lt) ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ ν∥Aa 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥AΛ t a 3 ̸ = ∥ L 2 + L∥Aa 1 ̸ = ∥ L 2 ∥AΛ −1 t p i,̸ = ∥ L 2 ∥A∂ t y a 3 ̸ = ∥ L 2 . Integrating in time yields T 2,2 dτ ≲ Lκ − 1 2 ε 3 .
To estimate T 2,3 , we need to distinguish between different choices of a.Using (32) we estimate
T 2,3 = k,l,k−l̸ =0 d(ξ, η)1 Ω 3 ν⟨t − ξ−η k−l ∧ κ − 1 3 ⟩ 1 |k−l,ξ−η| N −1 (ξ−η−(k−l)t)l−(k−l)(η−lt) ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≲ ν∥Aa 1 ̸ = ∥ L 2 ∥(Λ t ∧ κ − 1 3 )Ap i,̸ = ∥ L 2 ∥A∂ x a 3 ̸ = ∥ L 2 + ν∥Aa 1 ̸ = ∥ L 2 ∥A(Λ t ∧ κ − 1 3 )Λ −1 Λ −1 t p i,̸ = ∥ L 2 ∥A∂ t y a 3 ̸ = ∥ L 2
and thus after integrating in time
T 2,3 [vvv]dτ ≲ ν − 1 2 ε 3 , T 2,3 [bvb]dτ ≲ κ − 1 2 ε 3 , T 2,3 [bbv]dτ ≲ κ − 1 2 ε 3 .
In the case of vbb, we use (32) to estimate
T 2,3 [vbb] = k,l,k−l̸ =0 d(ξ, η)ν⟨t − ξ−η k−l ⟩ 1 |k−l,ξ−η| N −1 (ξ−η−(k−l)t)k−(k−l)(ξ−kt) ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Av)(k, ξ)(Ap 2 )(k − l, ξ − η)(Ab)(l, η) ≲ ν∥∂ x Av ̸ = ∥ L 2 ∥(Λ t ∧ κ − 1 3 )Ap 2,̸ = ∥ L 2 ∥Ab ̸ = ∥ L 2 + ν∥∂ t y Av ̸ = ∥ L 2 ∥(Λ t ∧ κ − 1 3 )Λ −1 t Ap 2,̸ = ∥ L 2 ∥Ab ̸ = ∥ L 2 ≤ ν∥Ab ̸ = ∥ L 2 ∥A∇ t v ̸ = ∥ L 2 ∥AΛ t p 2,̸ = ∥ L 2 .
Thus after integrating in time, we obtain
T 2,3 [vbb]dτ ≲ ν 1 2 κ − 1 2 ε 3 . For T 2,4 we obtain that M (l, η) = M (k − l, ξ − η) = 1. We use t − ξ k ≥ ν ≥ max(t − η l , t − ξ−η k−l ) to deduce that 1 = kt−ξ kt−ξ = k k t− ξ k t− ξ k ≤ ν |ξ−kt| |k| . With ξl − kη = (ξ − η − (k − l)t)l − (k − l)(η − lt) we infer that T 2,4 = k,l,k−l̸ =0 d(ξ, η) 1 |k−l,ξ−η| N ξl−kη ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) = ν k,l,k−l̸ =0 d(ξ, η)|ξ − kt| 1 |k−l,ξ−η| N −1 (ξ−η−(k−l)t)l |l|((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) + k,l,k−l̸ =0 d(ξ, η) 1 |k−l,ξ−η| N −1 (k−l)(η−lt) ((k−l) 2 +(ξ−η−(k−l)τ ) 2 ) 1 2 (Aa 1 )(k, ξ)(Ap i )(k − l, ξ − η)(Aa 3 )(l, η) ≤ ν∥A∂ t y a 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥Aa 3 ̸ = ∥ L 2 + ∥Aa 1 ̸ = ∥ L 2 ∥Λ −1 t Ap i,̸ = ∥ L 2 ∥A∂ t y a 3 ̸ = ∥ L 2 .
Thus integrating in time yields
T 2,4 dτ ≲ κ − 1 2 ε 3 .
3.3.Nonlinear terms with an x-average in the second component.We apply the notation of ( 26)
⟨Aa 1 ̸ = , A(a 2 1,= ∂ x a 3 ̸ = ) − a 2 1,= ∂ x Aa 3 ̸ = ⟩ = k̸ =0 d(ξ, η)(Aa 1 )(k, ξ)(A(k, ξ) − A(k, η))ka 2 1 (0, ξ − η)a 3 (k, η) = R + T.
Here we split into reaction and transport terms according to the sets
Ω R = {|ξ − η| ≥ 1 8 |k, η|}, Ω T = {|ξ − η| < 1 8 |k, η|}. Reaction term On the set Ω R it holds that |ξ − η| ≥ 1 8 |k, η|, then we obtain |A(k, ξ) − A(k, η)| ≲ |ξ − η| N and thus with (32), it follows that k̸ =0 d(ξ, η)(Aa 1 )(k, ξ)(A(k, ξ) − A(k, η))ka 2 1 (0, ξ − η)a 3 (k, η) ≲ ∥Aa 1 ̸ = ∥ L 2 ∥a 2 = ∥ H N ∥∂ x a 3 ̸ = ∥ L ∞ ≲ ∥Aa 1 ̸ = ∥ L 2 ∥a 2 = ∥ H N ∥ 1 M L Aa 3 ̸ = ∥ L 2 ≲ L∥Aa 1 ̸ = ∥ L 2 ∥a 2 = ∥ H N ∥Aa 3 ̸ = ∥ L 2 . Integrating in time yields a bound R dτ ≲ Lκ − 1 3 ε 2 ε.
Transport term On the set Ω L it holds that |k, η| ≥ 1 8 |ξ − η|.By the mean value theorem there exists a θ ∈ [0, 1]
|k, η| N − |k, ξ| N ≲ |ξ − η||k, η − θξ| N −1 ≲ |ξ − η||k, η| N −1 .
Thus, we can estimate the difference in A by
|A(k, ξ) − A(k, η)| ≲ (M L (k, ξ) − M L (k, η))|k, ξ| N + M L (k, η)|k, ξ| N j=1,κ,ν,ν 3 |M j (k, ξ) − M j (k, η)| + M L (k, η)(|k, η| N − |k, ξ| N ) ≲ 1 k |ξ − η||k, ξ| N
where we used (37),( 39) and (40) to estimate the differences in M j .So we infer, that
T ≤ k̸ =0 d(ξ, η)1 Ω T |Aa 1 |(k, ξ)|a 2 1 |(0, ξ − η) 1 M L (k,η) |Aa 3 |(k, η).
and thus integrating in time yields
T dτ ≲ L∥Aa 1 ̸ = ∥ L 2 L 2 ∥a 2 = ∥ L ∞ H N ∥Aa 3 ̸ = ∥ L 2 L 2 ≲ Lκ − 1 3 ε 2 ε.
3.4.Nonlinear terms with an x-average in the third component.We aim to estimate
⟨Aa 1 1,̸ = , A(a 2 2,̸ = ∂ y a 3 1,= )⟩ = k̸ =0 d(ξ, η)(Aa 1 1 )(k, ξ)A(k, ξ) kη √ k 2 +(ξ−η−kt) 2 p i (k, ξ − η)a 3 1 (0, η) = R + T
where we split into the reaction and transport terms according to the sets
Ω R = {|k, ξ − η| ≥ 1 8 |η|}, Ω T = {|k, ξ − η| < 1 8 |η|}. Reaction term On the set Ω R it holds that |k, ξ − η| ≥ 1 8 |η|. With (32) we infer R = k̸ =0 d(ξ, η)1 Ω R (Aa 1 1 )(k, ξ)A(k, ξ) kη √ k 2 +(ξ−η−kt) 2 p i (k, ξ − η)a 3 1 (0, η) ≲ ∥Aa 1 1,̸ = ∥ L 2 ∥A 1 M L ∂ x Λ −1 t p i,̸ = ∥ L 2 ∥∂ y a 3 1,= ∥ L ∞ ≲ ∥Aa 1 1,̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥a 3 1,= ∥ H N . Integrating in time then yields Rdτ ≲ κ − 1 3 ε 2 ε.
Transport term On the set Ω T it holds that |k, ξ − η| ≤ 1 8 |η|, then with (32) we estimate
T = k̸ =0 d(ξ, η)1 Ω T (Aa 1 1 )(k, ξ)A(k, ξ) kη √ k 2 +(ξ−η−kt) 2 p i (k, ξ − η)a 3 1 (0, η) ≲ ∥Aa 1 ̸ = ∥ L 2 ∥∂ x Λ −1 t p i,̸ = ∥ L ∞ ∥∂ y a 3 = ∥ H N ≲ ∥Aa 1 ̸ = ∥ L 2 ∥ 1 M L AΛ −1 t p i,̸ = ∥ L 2 ∥∂ y a 3 = ∥ H N ≲ ∥Aa 1 ̸ = ∥ L 2 (∥Λ −1 t Ap i ∥ L 2 + ν∥Ap i,̸ = ∥ L 2 )∥∂ y a 3 = ∥ H N . Integrating in time yields T dτ ≲ κ − 1 2 ε 2 ε.
3.5.Nonlinear terms with an x-average in first component.Now we turn to
⟨⟨∂ y ⟩ N a 1 =,1 , ⟨∂ y ⟩ N (a 2 ̸ = ∇ t a 3 ̸ =,1 ) = ⟩ = − k̸ =0 d(ξ, η)⟨ξ⟩ 2N a 1 1 (0, ξ) kξ √ k 2 +(ξ−η+kt) 2 p i (−k, ξ − η)a 3 1 (k, η).
Applying Hölder's inequality, the Sobolev embedding and the definition of A yields
⟨⟨∂ y ⟩ N a 1 1,= , ⟨∂ y ⟩ N (a 2 ̸ = ∇ t a 3 ̸ =,1 ) = ⟩ ≤ ∥∂ y ⟨∂ y ⟩ N a 1 = ∥ L 2 (∥∂ x Λ −1 t p i,̸ = ∥ L ∞ ∥⟨∂ y ⟩ N a 3 ̸ = ∥ L 2 + ∥⟨∂ y ⟩ N Λ −1 t p i,̸ = ∥ L 2 ∥∂ x a 3 ̸ = ∥ L ∞ ≤ ∥∂ y a 1 = ∥ H N ∥A 1 M L Λ −1 t p i,̸ = ∥ L 2 ∥A 1 M L a 3 ̸ = ∥ L 2 With (32) we infer ⟨⟨∂ y ⟩ N a 1 1,= , ⟨∂ y ⟩ N (a 2 ̸ = ∇ t a 3 ̸ =,1 ) = ⟩ ≲ ∥∂ y a 1 = ∥ H N (∥AΛ −1 t p i,̸ = ∥ L 2 + ν∥Ap i,̸ = ∥ L 2 )(∥Aa 3 ̸ = ∥ L 2 + ν∥A(Λ t ∧ κ − 1 3 )a 3 ̸ = ∥ L 2 ) ≲ ∥∂ y a 1 = ∥ H N ∥AΛ −1 t p i,̸ = ∥ L 2 (∥Aa 3 ̸ = ∥ L 2 + ν∥(Λ t ∧ κ − 1 3 )a 3 ̸ = ∥ L 2 ) + ν∥∂ y a 1 = ∥ H N ∥Ap i,̸ = ∥ L 2 (∥Aa 3 ̸ = ∥ L 2 + ν∥(Λ t ∧ κ − 1 3 )a 3 ̸ = ∥ L 2 ). Integrating in time yields ⟨⟨∂ y ⟩ N a 1 = , ⟨∂ y ⟩ N (a 2 ̸ = ∇ t a 3 ̸ =,1 ) = ⟩dτ ≲ Lκ − 1 2 ε 2 ε.
3.6.Other nonlinear terms.In this subsection, we aim to estimate
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 ∇ t a 3 )⟩ = ⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 ̸ = ∇ t a 3 ̸ = )⟩ + ⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 ̸ = ∇ t a 3 = )⟩ + ⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 = ∇ t a 3 ̸ = )⟩.
with the choices a 1 a 2 a 3 ∈ {bvv, bbb, vbv, vvb}.We start with the case of no xaverages and use
ξl − kη = (ξ − kt)(l − k) + k(ξ − η − (k − l)t)
and (32) to infer
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 ̸ = ∇ t a 3 ̸ = )⟩ = k,l,k−l̸ =0 d(ξ, η) ξ−kt k 2 +(ξ−kt) 2 ξl−kη √ (k−l) 2 +(ξ−η−(k−l)t) 2 A 2 (k, ξ)a 1 (k, ξ)p i (k − l, ξ − η)a 3 (l, η) ≲ ∥Aa 1 ̸ = ∥ L 2 ∥ 1 M L ∂ x Λ −1 t Ap i,̸ = ∥ L 2 ∥ 1 M L Aa 3 ̸ = ∥ L 2 + ∥∂ x Λ −1 t Aa 1 ̸ = ∥ L 2 ∥ 1 M L Ap i,̸ = ∥ L 2 ∥ 1 M L Aa 3 ̸ = ∥ L 2 ≲ L∥Aa 1 ̸ = ∥ L 2 (∥∂ x Λ −1 t Ap i,̸ = ∥ L 2 + ν∥Ap i,̸ = ∥ L 2 )∥Aa 3 ̸ = ∥ L 2 + L(1 + νκ − 1 3 )∥∂ x Λ −1 t Aa 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥Aa 3 ̸ = ∥ L 2 .
Thus integrating in time yields
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 ̸ = ∇ t a 3 ̸ = )⟩dτ ≲ Lκ − 1 2 ε 3 .
For the case, when the average is in the second component, we use partial integration to estimate
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 1,= ∂ x a 3 ̸ = )⟩ = −⟨χA∂ x ∂ t y ∆ −1 t a 1 ̸ = , A(a 2 1,= a 3 ̸ = )⟩ ≲ ∥∂ x Λ −1 t a 1 ̸ = ∥ L 2 ∥a 2 = ∥ H N ∥ 1 M L Aa 3 ̸ = ∥ L 2 ≲ L∥∂ x Λ −1 t a 1 ̸ = ∥ L 2 ∥a 2 = ∥ H N ∥Aa 2 ̸ = ∥ L 2
and thus integrating in time and using L = max(1, νκ − 1 3 ) yields
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 1,= ∂ x a 3 ̸ = )⟩dτ ≲ κ − 1 2 ε 2 ε.
For the case when the average is in the third component, we obtain
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 2,̸ = ∂ y a 3 = )⟩ = k̸ =0 d(ξ, η)χ ξ−kt k 2 +(ξ−kt) 2 kη √ k 2 +(ξ−η−t) 2 A(ξ,k) A(ξ−η,k) (Aa 1 )(k, ξ)(Ap i )(k, ξ − η)a 3 (0, η).
Thus by η = ξ − kt − (ξ − η − kt) we estimate
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 2,̸ = ∂ y a 3 = )⟩ ≤ ∥(∂ t y ) 2 ∆ −1 t Aa 1 ̸ = ∥ L 2 ∥∂ x Λ −1 t 1 M L Ap i,̸ = ∥ L 2 ∥a 3 = ∥ H N + ∥∂ x ∂ t y ∆ −1 t Aa 1 ̸ = ∥ L 2 ∥ 1 M L Ap i,̸ = ∥ L 2 ∥a 3 = ∥ H N ≤ L∥Aa 1 ̸ = ∥ L 2 ∥∂ x Λ −1 t Ap i,̸ = ∥ L 2 ∥a 3 = ∥ H N + L∥∂ x Λ −1
t Aa 1 ̸ = ∥ L 2 ∥Ap i,̸ = ∥ L 2 ∥a 3 = ∥ H N Integrating in time and using L = max(1, νκ − 1 3 ) yields
⟨χA∂ t y ∆ −1 t a 1 ̸ = , A(a 2 2,̸ = ∂ y a 3 = )⟩dτ ≲ κ − 1 2 ε 2 ε.
Which concludes the estimate
ON Ldτ ≲ Lκ − 1 2 εε 2 .
Combining the estimates of Subsection 3.2 to 3.6 completes the proof of Proposition 3.1and thus Theorem 3.1.□
In this article, we have shown that the MHD equations around Couette flow with magnetic resistivity smaller than fluid viscosity ν ≥ κ > 0 are stable for initial data which is small enough in Sobolev spaces.If the resistivity is much smaller than the viscosity, νκ − 1 3 > 0, large viscosity destabilizes the equation, leading to norm
The case M 1 (k, ξ) ≥ M 1 (l, η) follows by the same argument and M 1 (k, ξ) ≈ M 1 (l, η) ≈ 1.For (39) we consider the case M L (k, ξ) ≤ M L (k, η) and thus (k,η) .We infer
M L (k, η) − M L (k, ξ) = M L (k, η)(1 − M L (k,ξ) M L (k,η) ) ≲ 1 − M L (k,ξ) M L1 − M L (k,ξ) M L (k,η) = 1 − exp − t 0 τ − ξ k 1+(τ − ξ k ) 2 dτ − t 0 τ − η k 1+(τ − η k ) 2 dτ , = 1 − exp − −[ ξ k , η k ]∪t−[ ξ k , η k ]
1dτ , ≤ 2 |ξ−η| k .The case M L (k, ξ) ≥ M L (k, η) follows by the same argument.
(1) Let q ∈ X, then we obtain for p = F (q)
∂ t ∥p∥ 2 H N + κ∥∇ t p∥ 2 H N ≤ ∥p∥ 2 H N + ⟨Λ N v, Λ N (∇ ⊥ t Λ −1 t q 2 ∇ t b − ∇ ⊥ t Λ −1 t q 1 ∇ t v)⟩ + ⟨Λ N b, Λ N (∇ ⊥ t Λ −1 t q 2 ∇ t v − ∇ ⊥ t Λ −1 t q 1 ∇ t b)⟩ ≤ ∥p∥ 2 H N + ∥p∥ H N ∥q∥ H N ∥∇ t p n+1 ∥ H N ≤ ∥p∥ 2 H N + 2 κ ∥p∥ 2 H N ∥q∥ 2 H N + κ 2 ∥∇ t p∥ 2 H N . Thus we obtain ∥p∥ 2 X ≤ ∥p in ∥ 2 H N + T (1 + 1 κ ∥q∥ 2 L ∞ H N )∥p∥ 2 L ∞ H N ≤ ∥p in ∥ 2 H N + T (1 + 2 κ ∥p in ∥ 2 H N )∥p∥ 2 L ∞ H N , Since T (1 + 4 κ ∥p in ∥ 2 H N ) < 1 2
we infer the bound ∥p∥ 2 X ≤ 2∥p in ∥ 2 H N .As ∂ t p ∈ H N −2 , it follows that p ∈ CH N −2 and thus p ∈ X.
(2) We show that F is a contraction.Let q, q ∈ X we denote p = F (q) and p = F (q).We need to show that ∥p − p∥ X < 1 2 ∥q − q∥ X , by time estimate we obtain
∂ t ∥p − p∥ 2 H N + κ∥∇ t (p − p)∥ 2 H N ≤ ∥p − p∥ 2 H N + ⟨Λ N (v − ṽ), Λ N (∇ ⊥ t Λ −1 t q 2 ∇ t b − ∇ ⊥ t Λ −1 t q 1 ∇ t v)⟩ + ⟨Λ N (b − b), Λ N (∇ ⊥ t Λ −1 t q 2 ∇ t v − ∇ ⊥ t Λ −1 t q 1 ∇ t b)⟩ − ⟨Λ N (v − ṽ), Λ N (∇ ⊥ t Λ −1 t q2 ∇ t b − ∇ ⊥ t Λ −1 t q1 ∇ t v)⟩ − ⟨Λ N (b − b), Λ N (∇ ⊥ t Λ −1 t q2 ∇ t ṽ − ∇ ⊥ t Λ −1 t q1 ∇ t b)⟩ ≤ ∥p∥p − p∥ 2 L ∞ H N + κ 2 ∥∇ t (p − p)∥ 2 L 2 H N ≤ ∥p − p∥ 2 L ∞ H N T (1 + 2 κ ∥q∥ 2 L ∞ H N ) + √ T ∥p − p∥ L ∞ H N ∥q − q∥ L ∞ H N ∥∇ t p∥ L 2 H N ≤ ∥p − p∥ 2 L ∞ H N T (1 + 2 κ ∥q∥ 2 L ∞ H N + 4∥∇ t p∥ 2 L 2 H N ) + T 4 ∥q − q∥ 2 L ∞ H N .
Choosing T such that
Figure 1 .
1
Figure 1.Sketch of areas with results for stability.
− p∥ 2 H N + ∥p − p∥ H N (∥q − q∥ H N ∥∇ t p∥ H N + ∥q∥ H N ∥∇ t (p − p)∥ H N ) ≤ ∥p − p∥ 2 H N (1 + 2 κ ∥q∥ 2 H N ) + ∥p − p∥ H N ∥q − q∥ H N ∥∇ t p∥ H N + κ 2 ∥∇ t (p − p)∥ 2 H N .Integrating in time yields
T (1 + 2 κ ∥q∥ 2 H N + ∥∇ t p∥ 2 L 2 H N ) ≤ T + 2T ∥p in ∥ H N (1 + 8
κ ) < 1 2 ,it follows, that∥p − p∥ 2 X ≤ 1 2 ∥p − p∥ H N + T 4 ∥q − q∥ 2 L ∞ H N .We hence conclude, that∥p − p∥ 2 X ≤ 1 2 ∥q − q∥ 2 X .□
− M 1 (k,ξ) M 1 (k,η) ≲ |ξ−η| |k| , (37)
Acknowledgements.Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) -Project-ID 258734477 -SFB 1173.The author declares that they have no conflict of interest.This article is part of the PhD thesis of Niklas Knobel.Data availability.No data was used for the research described in the article.We use (33) and (34) to inferIntegrating in time yieldsTransport term: On the set Ω T it holds that |k − l, ξ − η| < 1 8 |l, η| and thus it follows that |k, ξ| ≈ |l, η|.By the mean value theorem, there exists θ ∈ [0, 1] such thatThus with (27) and Lemma 4 we conclude, thatinflation of size νκ − 1 3 .Controlling this norm inflation is a major new challenge compared to other dissipation regimes.Appendix A. Construction of the WeightsLet A be the Fourier weightThe weight M L is an adaption of the weight m 1 2 in[Lis20]to the present setting and M ν 3 we use to differentiate between resonant and non-resonant regions.The method of using time-dependent Fourier weights is common when working at solutions around Couette flow and the other weights are modifications of previously used weights (cf.[BVW18, MZ22, Lis20, ZZ23] for shear related systems such as Navier-Stokes).The constants) are determined through the linear estimates.For the weights we obtain that for all times t > 0, it holds thatLemma 2 (M L properties ).The weight M L satisfies the following boundsProof.This follows immediately, from the definition of M L .□ Lemma 3 (Enhanced dissipation estimates ).The weights M ν and M κ satisfy the following boundsProof.This follows immediately, from the definition of M ν and M κ .□ Lemma 4 (Difference estimates).Let k, l ∈ Z \ {0} and ξ, η ∈ R, then there hold the following bounds on differences For (40) we estimate the M κ difference, since the M ν and M ν 3 differences are done similar.Let M κ (k, ξ) ≥ M κ (l, η), then it followsThe case M κ (k, ξ) ≤ M κ (l, η) follows from the same steps and M κ (k, ξ) ≈ M κ (l, η).□Appendix B. Local WellposednessWe expect the local wellposedness result to be well-known, but were not able to find it stated in the literature.In the following, we prove the local wellposedness by a standard application of the Banach fixed-point theorem.Proposition 5. Consider equation (14) with initial data p in ∈ H N for N ≥ 5. Then there exists a time T such that there exists a unique solution p(t) ∈ H N to (14) for all t ∈ [0, T ] .Proof.We prove existence with the Banach fixed-point theorem.Let T = 1 + 2∥p in ∥ H N (1 + 8 κ ) and let X be the spaceWe define F : X → X as a mapping q → p = F (q) such that p solvesThen the mapping F satisfies:(1) The mapping F : X → X is well defined on X.(2) The mapping F is a contraction, i.e. ∥F (p) − F (p)∥ L ∞ H N ≤ 1 2 ∥p − p∥ L ∞ H N .Since X is a complete metric space, if we prove (1) and (2), then it follows that F has a unique fixpoint by the Banach fixed-point theorem.
Nonlinear inviscid damping and shear-buoyancy instability in the two-dimensional Boussinesq equations. Jacob Bedrossian, Roberta Bianchini, Michele Coti Zelati, Michele Dolce, Communications on Pure and Applied Mathematics. 76122023
On the stability threshold for the 3D Couette flow in Sobolev regularity. Jacob Bedrossian, Pierre Germain, Nader Masmoudi, Annals of Mathematics. 2017
Asymptotic stability for the Couette flow in the 2D Euler equations. Jacob Bedrossian, Nader Masmoudi, Applied Mathematics Research eXpress. 201412014
Inviscid damping and the asymptotic stability of planar shear flows in the 2D Euler equations. Jacob Bedrossian, Nader Masmoudi, Publ. Math. Inst. Hautes Études Sci. 1222015
Longtime dynamics of a conductive fluid in the presence of a strong magnetic field. Catherine Bardos, P-L Sulem, Sulem, Transactions of the American Mathematical Society. 30511988
The Sobolev stability threshold for 2D shear flows near Couette. Jacob Bedrossian, Vlad Vicol, Fei Wang, Journal of Nonlinear Science. 2862018
Elsässer formulation of the ideal MHD and improved lifespan in two space dimensions. Dimitri Cobb, Francesco Fanelli, Journal de Mathématiques Pures et Appliquées. 1692023
Introduction to Magnetohydrodynamics. P A Davidson, Cambridge Texts in Applied Mathematics. 2016Cambridge University Press2 edition
Long-time instability of the Couette flow in low Gevrey spaces. Yu Deng, Nader Masmoudi, Communications on Pure and Applied Mathematics. 2018
Stability threshold of the 2D Couette flow in a homogeneous magnetic field using symmetric variables. Michele Dolce, arXiv:2308.125892023arxiv preprint
Echo chains as a linear mechanism: Norm inflation, modified exponents and asymptotics. Archive for rational mechanics and analysis. Yu Deng, Christian Zillinger, 2021242
Instability of MHD Couette flow of an electrically conducting fluid. Zakir Hussain, Sultan Hussain, Tiantian Kong, Zhou Liu, AIP Advances. 8102018
On the instability of magnetohydrodynamic shear flows. D W Hughes, Tobias, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences. 4572010. 2001
On global dynamics of three dimensional magnetohydrodynamics: nonlinear stability of Alfvén waves. Ling-Bing He, Li Xu, Pin Yu, Annals of PDE. 412018
Nonlinear inviscid damping near monotonic shear flows. D Alexandru, Hao Ionescu, Jia, Acta Mathematica. 23022013
Weak and classical solutions of the two-dimensional magnetohydrodynamic equations. Hideo Kozono, Tohoku Mathematical Journal, Second Series. 4131989
On echoes in magnetohydrodynamics with magnetic dissipation. Niklas Knobel, Christian Zillinger, Journal of Differential Equations. 3672023
On the Sobolev stability threshold for the 2D MHD equations with horizontal magnetic dissipation. Niklas Knobel, Christian Zillinger, arXiv:2309.004962023arXiv preprint
On the Sobolev stability threshold of 3D Couette flow in a uniform magnetic field. Kyle Liss, Communications in Mathematical Physics. 2020
A resolution of the Sommerfeld paradox. Y , Charles Li, Zhiwu Lin, SIAM Journal on Mathematical Analysis. 4342011
Stability threshold of two-dimensional Couette flow in Sobolev spaces. Nader Masmoudi, Weiren Zhao, Ann. Inst. H. Poincaré C Anal. Non Linéaire. 3922022
Asymptotic stability for twodimensional Boussinesq systems around the Couette flow in a finite channel. Nader Masmoudi, Cuili Zhai, Weiren Zhao, Journal of Functional Analysis. 28411097362023
Global existence and decay of smooth solution for the 2-D MHD equations without magnetic diffusion. Jiahong Xiaoxia Ren, Zhaoyin Wu, Zhifei Xiang, Zhang, Journal of Functional Analysis. 26722014
On a magnetohydrodynamic problem of Euler type. Paul Günter, Schmidt , Journal of differential equations. 7421988
Global well-posedness of the MHD equations in a homogeneous magnetic field. Dongyi Wei, Zhifei Zhang, Analysis & PDE. 1062017
On the Boussinesq equations with non-monotone temperature profiles. Christian Zillinger, Journal of Nonlinear Science. 314642021
Asymptotic stability of Couette flow in a strong uniform magnetic field for the Euler-MHD system. Weiren Zhao, Ruizhao Zi, arXiv:2305.040522023arXiv preprint
| [
-0.15455353260040283,
-0.09349343925714493,
-0.023453013971447945,
-0.06960711628198624,
0.11991901695728302,
0.13706925511360168,
-0.09375622868537903,
0.008189313113689423,
-0.058223381638526917,
-0.10272335261106491,
-0.16299864649772644,
-0.07656939327716827,
0.13579687476158142,
-0.18... |
Sketching Cuts in Graphs and Hypergraphs
September 9, 2014
Dmitry Kogan dmitry.kogan@weizmann.ac.il
Weizmann Institute of Science
Robert Krauthgamer robert.krauthgamer@weizmann.ac.il
Weizmann Institute of Science
Sketching Cuts in Graphs and Hypergraphs
September 9, 2014A0E7265CCFD59F77E090E4C2B7190DFAarXiv:1409.2391v1[cs.DS]
Sketching and streaming algorithms are in the forefront of current research directions for cut problems in graphs.In the streaming model, we show that (1 − ε)-approximation for Max-Cut must use n 1−O(ε) space; moreover, beating 4/5-approximation requires polynomial space.For the sketching model, we show that r-uniform hypergraphs admit a (1 + ε)-cut-sparsifier (i.e., a weighted subhypergraph that approximately preserves all the cuts) with O(ε −2 n(r + log n)) edges.We also make first steps towards sketching general CSPs (Constraint Satisfaction Problems).
Introduction
The emergence of massive datasets has turned many algorithms impractical, because the standard assumption of having (fast) random access to the input is no longer valid.One example is when data is too large to fit in the main memory (or even on disk) of one machine; another is when the input can be accessed only as a stream, e.g., because its creation rate is so high, that it cannot even be stored in full for further processing.Luckily, the nature of the problems has evolved too, and we may often settle on approximate, rather than exact, solutions.
These situations have led to the rise of new computational paradigms.In the streaming model (aka data-stream), the input can be accessed only as a stream (i.e., a single pass of sequential access), and the algorithm's space complexity (storage requirement) must be small relative to the stream size.In the sketching model, the input is summarized (compressed) into a so-called sketch, which is short and suffices for further processing without access to the original input.The two models are related -sketches are often useful in the design of streaming algorithms, and vice versa.In particular, lower bounds for sketch-size often imply lower bounds on the space complexity of streaming algorithms.
Graph problems.
Recently, the streaming model has seen many exciting developments on graph problems, where an input graph G = (V, E) is represented by a stream of edges.The algorithm reads the stream and should then report a solution to a predetermined problem on G, such as graph connectivity or maximum matching; see e.g. the surveys [Zha10,McG14].Throughout it will be convenient to denote n = |V |, and to assume edges have weights, given by w : E → R + .While initial efforts focused on polylogarithmic-space algorithms, various intractability results have shifted the attention to what is called the semi-streaming model, where the algorithm's space complexity is Õ(n). 1 In general, this storage is not sufficient to record the entire edge-set.
Cuts in graphs is a classical topic that has been studied extensively for more than half a century, and the last two decades have seen a surge of attention turning to the question of their succinct representation.The pioneering work of Benczúr and Karger [BK96] introduced the notion of cut sparsifiers: given an undirected graph G = (V, E, w), a (1 + ε)-sparsifier is a (sparse) weighted subgraph G = (V, E , w ) that preserves the value of every cut up to a multiplicative factor 1 + ε.Formally, this is written as
∀S ⊂ V,
1 ≤ w (S, S) w(S, S) ≤ 1 + ε;
but it is sometimes convenient to replace the lefthand-side with 1 − ε or 1 1+ε , which affects ε ≤ 1 2 by only a constant factor.In addition to their role in saving storage, sparsifiers are important because they can speed-up graph algorithms whose running time depends on the number of edges.
Observe that sparsifiers are a particularly strong form of graph-sketches since on top of retaining the value of all cuts, they hold the additional property of being subgraphs, rather than arbitrary data structures.Ahn and Guha [AG09] built upon the machinery of cut sparsifiers to present an Õ(n/ε 2 )-space streaming algorithm that can produce a (1 + ε)-approximation to all cuts in a graph.Further improvements handle also edge deletions [AGM12a, AGM12b, GKP12], or the stronger notion of spectral sparsification (see [KLM + 11] and references therein).These results are nearly optimal, due to a space lower bound of Ω(n/ε 2 ) for sketching all cuts in a graph [AKW14] (which improves an earlier bound of [AG09]).
Recent Directions.These advances on sketching and streaming of graph cuts inspired new questions.One direction is to seek space-efficient streaming algorithms for specific cut problems, such as approximating Max-Cut, rather than all cuts.A second direction concerns hypergraphs, asking whether cut sparsification, sketching and streaming can be generalized to hypergraphs.Finally, viewing cuts in graphs and hypergraphs as special cases of constraint satisfaction problems (CSPs), we ask whether other CSPs also admit sketches.Currently, there is a growing interest in generalizing graph cut problems to broader settings, such as sparsifying general set systems using small weighted samples [NR13], high-dimensional expander theory [KKL14], sparsest-cuts in hypergraphs [LM14,Lou14], and applications of hypergraph cuts in networking [YOTI14].
Our Results
We first address a natural question raised in [IMNO11, Question 10], whether the well-known Max-Cut problem admits approximation strictly better than factor 1/2 by streaming algorithms that use space sublinear in n.Here, Max-Cut denotes the problem of computing the value of a maximum cut in the input graph G (and not the cut itself), since reporting a cut requires space Ω(n) (see Subsection 2.2 for a short proof).We prove that for every fixed ε ∈ (0, 1 5 ), streaming algorithms achieving (1 − ε)-approximation for Max-Cut must use n 1−O(ε) space.In fact, even beating 4/5-approximation requires polynomial space.Our result is actually stronger and holds also in a certain sketching model.Previously, it was known that streaming computation of Max-Cut exactly requires Ω(n2 ) bits [Zel11].Our proof is by reduction from the Boolean Hidden Hypermatching problem, and captures the difficulty of distinguishing, under limited communication, whether the graph is avertex-disjoint union of even-length cycles (in which case the graph is bipartite) or of odd-length cycles (in which case we can bound the maximum cut value).See Section 2 for details.
Second, we study sparsification of cuts in hypergraphs, and prove that every r-uniform hypergraph admits a sparsifier (weighted subhypergraph) of size Õ(rn/ε 2 ) that approximates all cuts within factor 1 ± ε.This result immediately implies sketching and streaming algorithms (following [AG09]).Here, the weight of cut (S, S) in a hypergraph H = (V, E, w) is the total weight of all hyperedges e ∈ E that intersect both S and S. 2 This question was raised by de Carli Silva et al. [dCHS11,Corollary 8], who show that every r-uniform hypergraph has a sparsifier of size O(n) that approximates all cuts within factor Θ(r 2 ).As hypergraph cuts can be viewed as setsystems, sparsifiers of size O(n 2 ), regardless of r, follow implicitly from [NR13].Along the way, we establish interesting, if not surprising, bounds on the number of approximately minimum cuts in hypergraphs.Technically, this is our most substantial contribution, see Section 3 for details.
Finally, as a step towards understanding a wider range of CSPs, we show that k-SAT instances on n variables admit a sketch of size Õ(kn/ε 2 ) that can be used to (1 + ε)-approximate the value of all truth assignments.We prove this result in Section 3.3 by reducing it to hypergraph sparsification.We remark that sketching of SAT formulae was studied in a different setting, where some computational-complexity assumptions were used in [DvM10] to preclude a significant sizereduction that preserves the satisfiability of the formula.Our sparsification result differs in that it approximately preserves the value of all assignments.
Related Work.Independently of our work, Kapralov, Khanna and Sudan [KKS14] studied the same problem of approximating Max-Cut in the streaming model.They first prove that for every fixed ε > 0, streaming algorithms achieving (1 − ε)-approximation for Max-Cut must use n 1−O(ε) space.(This is similar to our Theorem 2.1.)They then make significant further progress, and show that achieving an approximation ratio strictly better than (the trivial) 1/2 require Ω( √ n) space.
In fact, this result holds even if the edges of the graph are presented in a random (rather than adversarial) order.
Sketching Max-Cut
The classical Max-Cut problem is perhaps the simplest Max-CSP problem.Therefore, it has been studied extensively, leading to fundamental results both in approximation algorithms [GW95] and in hardness of approximation [KKMO04].It is thus natural to study Max-Cut also in the streaming model.As mentioned above, preserving the values of all cuts in a graph requires linear space even if only approximate values are required [AG09, AKW14], which raises the question whether smaller space suffices to approximate only the Max-Cut value (as mentioned above, it is natural to require the algorithm to report only the value of the cut as opposed to the cut itself, see Section 2.2).
Sketching all cuts in a graph clearly preserves also the maximum-cut value, and thus an Õ n ε 2 space streaming algorithm for a (1 − ε)-approximation of Max-Cut follows immediately from [AG09].Yet since the maximum cut value is always Ω(m), where m is the total number (or weight) of all edges, a similar result can be obtained more easily by uniform sampling (achieving εm additive approximation for all cuts) [Zel09, Theorem 21].The latter approach has the additional advantage that it immediately extends to hypergraphs.It turns out that this relatively straightforward approach is not far from optimal, as we prove that streaming algorithms that give a (1 − ε)-approximation for Max-Cut require n 1−O(ε) space.
Theorem 2.1.Fix a constant ε ∈ (0, 1 5 ).Every (randomized) streaming algorithm that gives a (1 − ε)-approximation of the Max-Cut value in n-vertex graphs requires space Ω(n 1−1/t ) for t = 1 2ε − 1 2 , which in particular means space n 1−O(ε) .
To prove this result, we consider the somewhat stronger one-way two-party communication model, where instead of arriving as a stream, the set of edges of a graph is split between two parties, who engage in a communication protocol to compute (approximately) the graph's maximum-cut value.Since a lower bound in this model immediately translates to the original streaming model, the theorem above follows immediately from Theorem 2.3 below.
Proof of Theorem
2.1 Definition 2.2 (Max-Cut ε ). Let G = (V, E A ∪ E B
) be an input graph on |V | = n vertices with maximum cut value3 c * , and ε > 0 some small constant.Max-Cut ε is a two player communication game where Alice and Bob receive the edges E A and E B respectively and need to output a value c such that with high probability
(1 − ε)c * ≤ c ≤ c * . Theorem 2.3. Fix a constant ε ∈ (0, 1 5 ). Then the randomized one-way communication complexity of Max-Cut ε is Ω(n 1−1/t ) for t = 1 2ε − 1 2 .
The proof is by a reduction from the following communication problem studied in [YV11].
Definition 2.4 (BHH t n ).The Boolean Hidden Hypermatching problem is a communication complexity problem where
• Alice gets a boolean vector x ∈ {0, 1} n where n = 2kt for some integer k,
• Bob gets a perfect hypermatching M on n vertices where each edge has t vertices and a boolean vector w of length n/t.
Let M x denote the length-n/t boolean vector
( 1≤i≤t x M 1,i , . . . , 1≤i≤t x M n/t,i ) where (M 1,1 , . . . , M 1,t ) , . . . ,(M n/t,1 , . . . , M n/t,t ) are the edges of M. It is promised that either M x ⊕ w = 1 n/t or M x ⊕ w = 0 n/t .
The problem is to return 1 in the former case, and to return 0 in the latter.where n = 2kt for some integer k ≥ 1 is Ω(n 1−1/t ).
Proof of Theorem 2.3.We show a reduction from BHH t n to Max-Cut ε .Consider an instance (x, M, w) of the BHH t n problem: Alice gets x ∈ {0, 1} n , and Bob gets a perfect hypermatching M and a vector w ∈ {0, 1} n/t .
We construct a graph G for the Max-Cut ε problem as follows (see Figure 2.1 for an example):
• The vertices of G are V = {v i } 2n i=1 ∪ {u i } 2n i=1 ∪ {w i } 2n/t i=1 . • The edges E A given to Alice are: for every i ∈ [n], if x i = 0, Alice is given two "parallel" edges (u 2i−1 , v 2i−1 ), (u 2i , v 2i ); if x i = 1, Alice is given two "cross" edges (u 2i−1 , v 2i ), (u 2i , v 2i−1 ).
• The edges E B given to Bob are: for each hyperedge M j = (i 1 , i 2 , . . ., i t ) ∈ M (where the order is fixed arbitrarily):
-For k = 1, 2, . . . , t − 1, Bob is given (u 2i k −1 , v 2i k+1 −1 ) and (u 2i k , v 2i k+1 ) -For k = t, Bob is given (u 2it , w 2j ) and (v 2it−1 , w 2j−1 ); -If w j = 0 Bob is given two "parallel" edges (w 2j , v 2i 1 ) and (w 2j−1 , v 2i 1 −1 ); if w j = 1, Bob is given two "cross" edges (w 2j , v 2i 1 −1 ) and (w 2j−1 , v 2i 1 ) By definition, for each j ∈ [n/t], if M j = (i 1 , i 2 , . . . , i t ) ∈ M and (M x) j ⊕ w j = 0 we have t k=1 x i k ⊕ w j = 0.
Since the number of 1 bits in the latter sum is even, when we start traversing from u 2i 1 we go through an even number of "cross" edges and complete a cycle of length 2t + 1. Similarly when starting our traversal at u 2i 1 −1 we complete a different cycle of the same length.Therefore if (x, M, w) is a 0-instance the graph consists of 2n t paths of (odd) length 2t + 1 each.Therefore the maximum cut value is c * 0 = 2t • 2n t = 4n.On the other hand if (M x) j ⊕ w j = 1, starting our traversal at u 2i 1 −1 , we pass an odd number of cross edges and end up at u 2i 1 , from where we once again pass an odd number of cross edges, to complete a cycle of total length 2 • (2t + 1) = 4t + 2 that ends back in u 2i 1 −1 .Therefore, if (x, M, w) is a 1-instance the graph consists of n/t paths of (even) length 4t + 2 each.The maximum cut value in this case is c * 1 = 4n + 2 n t .Observing that c * 0 /c * 1 = 4n 4n+2n/t = 2t 2t+1 < 1 − ε, we conclude that a randomized one-way protocol for Max-Cut ε (on input size n = 4n + n/t = O(n)) gives a randomized one-way protocol for BHH t n .By Lemma 2.5 the Theorem follows.
Proof of Theorem 2.3.Any streaming algorithm for Max-Cut ε leads to a one-way communication protocol in the two party setting.Moreover the communication complexity of this protocol is exactly the space complexity of the streaming algorithm.Hence by Theorem 2.3 the streaming space complexity is at least as high as the one way randomized communication complexity.
Reporting a Vertex-Bipartition (rather than a value)
We show a simple Ω(n) space lower bound for reporting a vertex-bipartition that gives an approximate maximum cut.
Proposition 2.6.Let ε ∈ (0, 1 2 ) be some small constant.Suppose sk is a sketching algorithm that outputs at most s = s(n, ε) bits, and est is an estimation algorithm, such that together, for every nvertex graph G, (with high probability) they output a vertex-bipartition that gives an approximately maximum cut; i.e., est(sk(G)) = S such that w(S, S) ≥ (1 − ε) w where w is the maximum cut in
G. Then s ≥ Ω ε (n). u 1 u 2 v 1 v 2 u 3 v 3 u 4 v 4 u 5 v 5 u 6 v 6 w 1 w 2 Figure 1:
An example of a gadget constructed in the proof of Theorem 2.3 for t = 3, a matching M that contains the hyperedge M 1 = (1, 2, 3), x 1 = 1, x 2 = 0, x 3 = 1 and w 1 = 0.The result is two paths of length 7. Alice's and Bob's edges are colored black and red respectively.%vspace20pt
Proof.Let C ⊂ {0, 1} n be a binary error-correcting code of size |C| = 2 Ω(n) with relative distance ε.
We may assume w.l.o.g. that for every x ∈ C the hamming weight |x| is exactly n/2 (for instance by taking C = {xx : x ∈ C} where x denotes the bitwise negation of x), and that there are no x, y ∈ C such that |x − ȳ| ≤ ε 2 n (since for every x ∈ C there could be at most one "bad" y, and we can discard one codeword out of every such pair).
Fix a codeword x ∈ {0, 1} n and consider the complete bipartite graph G x = (V, E) where V = [n] and E = {(i, j) :
x i = 0 ∧ x j = 1}. The maximum cut value in G x is obviously w = n 2 /4. Let y ∈ {0, 1} n such that 1 2 εn ≤ |x − y| ≤ n 2 .
Identifying x, y with subsets S x , S y ⊆ [n], and using the fact that |S x S y | = |x − y| ≥ 1 2 εn, the value of the cut (S y , Sy ) in G x is
|E(S y , Sy )| = n 2 4 − |S x \ S y | n 2 − |S y \ S x | − |S y \ S x | n 2 − |S x \ S y | < (1 − Ω(ε)) n 2 4
Let sk(G x ) be the sketch of G x , and let est(sk(G x )) = S be the output of the estimation algorithm on the sketch of G x .Therefore if the sketch succeeds (which by our assumption happens with high probability) and the cut (S, S) has value at least (1 − Ω(ε)) w, then by the preceding argument the corresponding vector x S is of relative hamming distance smaller than ε 2 from x and then one can decode x from S.4 By standard arguments from information theory, the size s of a sketch that succeeds with high probability must be at least Ω(log |C|) = Ω ε (n).
2/3-Approximation of Max-Cut in the Two Party Model
We remark that in the one-way two-party model, the parameter range ε ∈ (0, 1 5 ) in Theorem 2.3 is tight and not merely a technical limitation of our analysis.In that model, the problem of giving a 2t 2t+1 -approximation of the maximum cut exhibits an exponential gap in the communication complexity between the case of t ≥ 2, where we have shown that a polynomial number of bits is necessary, and the case t = 1, for which logarithmically many bits suffice, as follows from the following simple protocol.
(w A + w B ) ≤ w ≤ w A + w B Proof. Consider cuts C A , C B : V → {0, 1} such that w(C A ) = w A and w(C B ) = w B . Let C : V → {0, 1} be a cut chosen uniformly at random from {C A , C B , C A + C B }. For an edge e = (u, v) ∈ C A , either C B (u) + C B (v) = 1 or (C A + C B )(u) + (C A + C B )(u) = (C A (u) + C A (v)) + (C B (u) + C B (v)) = 1 + 0 = 1. Either way Pr C∈ R {C A ,C B ,C A +C B } [e ∈ C] = 2
3 .Similarly the same holds for an edge e ∈ C B .Therefore by linearity of expectation a random cut in {C A , C B , C A + C B } has value at least 2 3 (w A + w B ).The second inequality is trivial.
Corollary 2.8.The one-way communication complexity of Max-Cut 1/3 is O(log n).
Proof.Alice computes the value w A and sends it to Bob. Bob computes the value w B and outputs
2 3 (w A + w B ).
Sketching Cuts in Hypergraphs
In a celebrated series of works, Karger [Kar95, Kar98, Kar99] and Benczúr and Karger [BK96,BK02] showed an effective method to sketch the values of all the cuts of an undirected (weighted) graph G = (V, E, w) by constructing a cut-sparsifier, which is a subgraph with different edge weights, that contains only Õ n/ε 2 edges, and approximates the weight of every cut in G up to a multiplicative factor of (1 ± ε).We generalize the ideas of Benczúr and Karger to obtain cut-sparsifiers of hypergraphs, as stated below.Such sparsifiers (and sketches) can be computed by streaming algorithms that use Õ(rn) space for r-uniform hypergraphs using known techniques (of [AG09] and subsequent work).
Theorem 3.1.For every r-uniform5 hypergraph H = (V, E, w) and an error parameter ε ∈ (0, 1), there is a subhypergraph H ε (with different edge weights) such that:
• H ε has O n(r + log n)/ε 2 hyperedges.
• The weight of every cut in H ε is (1 ± ε) times the weight of the corresponding cut in H.
A key combinatorial property exploited in the Benczúr-Karger analysis is an upper bound on the number of cuts of near-minimum weight [Kar93].It asserts that in the number of minimum-weight cuts in an n-vertex graph is at most n 2 (which had been previously shown by [LP72] and [DKL76]), and more generally, there are at most n 2α cuts whose weight is at most α ≥ 1 times the minimum.Correctly generalizing this property to r-uniform hypergraphs appears to be a nontrivial question.A fairly simple analysis generalizes the latter bound to n rα , but using new ideas, we manage to obtain the following tighter bound.Theorem 3.2.Let H = (V, E, w) be a weighted r-uniform hypergraph with n vertices and minimum cut value ŵ.Then for every half-integer α ≥ 1, the number of cuts in H of weight at most α ŵ is at most O(2 αr n 2α ).
We prove this "cut-counting" bound in Section 3.1.With this bound at hand, we prove Theorem 3.1 similarly to the original proof of [BK96] for graphs, as outlined in Subsection 3.2.
Cuts in hypergraphs are perhaps one of the simplest examples of CSPs, with the hypergraph vertices becoming boolean variables, and the hyperedges becoming constraints defined by the predicate Not-All-Equal.A natural question is whether general CSPs admit sketches as well, where a sketch should provide an approximation to the value of every assignment to the CSP (as usual, the value of an assignment is the number of constraints it satisfies).Although we are still far from answering this question in full generality, we prove that for the well-known SAT problem, sketching is indeed possible.
Theorem 3.3.For every error parameter ε ∈ (0, 1), there is a sketching algorithm that produces from an r-CNF formula Φ on n variables a sketch of size Õ(rn/ε 2 ), that can be used to (1 ± ε)approximate the value of every assignment to Φ.
Near-Minimum Cuts in Hypergraphs
In this subsection we prove our upper bound on the number of near-minimum cuts (Theorem 3.2).We generalize Karger's min-cut algorithm to hypergraphs, and then show that its probability to output any individual cut is not small (Theorem 3.4), which immediately yields a bound on the number of distinct cuts.Finally, we show that the exponential dependence on r in Theorem 3.2 is necessary (Section 3.1.3).
A Randomized Contraction Algorithm
Consider the following generalization of Karger's contraction algorithm [Kar93] to hypergraphs.
Algorithm 3.1 ContractHypergraph Input:
an r-uniform weighted hypergraph H = (V, E, w)
a parameter α > 1 Output: a cut C = (S, V \ S) 1: H ← H 2: while |V (H )| > αr do 3:
e ← random hyperedge in H with probability proportional to its weight
2 αr−1 −1 for Q n,r,α = 2α + 1 (r + 1) n − α(r − 2) 2α −1
Since Theorem 3.4 gives a lower bound on the probability to output a specific cut (of certain weight), and different cuts correspond to disjoint events, it immediately implies an upper bound on the possible number of cuts of that weight, proving Theorem 3.2.
Proof.Fix C = (S, V \ S) to be some cut of weight α ŵ in H.For t = 1, . . ., n, denote by I t the iteration of the algorithm where H contains t vertices.Since a contraction of a hyperedge may reduce the number of vertices by anywhere between 1 and r − 1, in a specific execution of the algorithm, not necessarily all the {I t } n t=1 occur.Similarly, let the random variable E t be the edge contracted in iteration t.
We say that an iteration I t is bad if E t ∈ C (i.e., the hyperedge contains vertices from both S and V \ S).Otherwise, we say it is good (including iterations that do not occur in the specific execution such as I 1 , . . ., I αr ).For any fixed e n , . . ., e t+1 ∈ E define q t (e n , . . ., e t+1 ) = Pr [I t , I t−1 , . . ., I 1 are good|E n = e n , . . ., E t+1 = e t+1 ] Note that q n is simply the probability that all iterations of the algorithm are good i.e., no edge of the cut C is contracted.When that happens, in step 5 of the algorithm, there exists a cut C in H that corresponds to the cut C in H. Since at that stage, there are at most αr vertices in H , the probability of choosing C is at least 1 2 αr−1 −1 .Hence the overall probability of outputting cut C is at least q n • 1 2 αr−1 −1 .We thus need to give a lower bound on q n .To this end we prove the following lemma.
Lemma 3.5.q t (e n , . . ., e t+1 ) ≥ Q t,r,α for every t = αr, . . ., n, and every e n , . . ., e t+1 ∈ E \ C.
Using the lemma for t = n bounds the overall probability of outputting cut C and proves Theorem 3.4.
Proof of Lemma 3.5
By (complete) induction on t.For the base case, note that q t (e n , . . ., e t+1 ) = 1 for t = 1, . . ., αr since no contractions take place in those iterations.
For the general case, fix an iteration I t and from now on, condition on some set of values E n = e n , . . ., E t+1 = e t+1 .All probabilities henceforth are thus conditioned, and for brevity we omit it from our notation.Observe that depending on the cardinality of E t , the next iteration (after iteration I t ) may be one of
I t−1 , . . . , I t−r+1 . Let p i = Pr[|E t | = i] and let y i = Pr [|E t | = i ∧ E t ∈ C]. 7,8
We can now write a recurrence relation: q t (e n , . . ., e t+1 ) = Pr[I t , . . ., I 1 are good|E n = e n , . . .,
E t+1 = e t+1 ] = r i=2 Pr [|E t | = i ∧ E t / ∈ C] • Pr[I t−i+1 , . . . , I 1 are good||E t | = i, E t / ∈ C] = r i=2 (p i − y i )E Et [q t−i+1 (e n , . . . , e t+1 , E t )||E t | = i ∧ E t / ∈ C] ≥ r i=2 (p i − y i )Q t−i+1,r,α
For i = 2, . . ., r let W i = e ∈H :|e |=i w(e ) be the total weight of hyperedges in H of cardinality i (at iteration t) and let W = r i=2 W i be the total weight in H . Observe that
p i = W i
W since E t is chosen with probability proportional to the hyperedge's weight, and v∈V deg(v) = r i=2 i • W i since a hyperedge of cardinality i is counted i times on the lefthand side.By averaging, there exists a vertex v ∈ V (H ) such that deg(v)
≤ 1 t r i=2 i • W i , and since it induces a cut in H whose weight is exactly deg(v), we obtain that ŵ ≤ deg(v) ≤ 1 t r i=2 i • W i . Next note that r i=2 y i = Pr[E t ∈ C] ≤ α ŵ W ≤ α t r i=2 i • W i W = α t r i=2 i • p i
where the first inequality uses the conditioning on all previous iterations being good, which means that all hyperedges in C have survived in H , and thus w H (C) = w H (C). Altogether, to prove the lemma it suffices to show that the value of the following linear program is at least Q t,r,α (and from now on we omit the subscripts r and α, denoting
Q t = Q t,r,α ). minimize r i=2 (p i − y i )Q t−i+1 subject to 0 ≤ y i ≤ p i ∀i = 2, . . . , r r i=2 p i = 1 r i=2 y i ≤ α t r i=2 i • p i .
First observe that the last constraint implies
r i=2 y i ≤ α t r i=2 i • p i ≤ α t r i=2 r • p i = αr t r i=2 p i < r i=2 p i ,(1)
which means that in every feasible solution there is always some y i < p i .This implies that in every optimal solution, the last constraint is tight, since otherwise increasing such a y i will decrease the value of the solution, without violating any of the other constraints.
It is easy to see that this linear program is both feasible and bounded, and therefore has an optimal solution that is basic (i.e., a vertex of the polytope).The dimension of the linear program (i.e., the number of variables) is 2r − 2, and thus in a basic feasible solution (at least) 2r − 2 of the 2r constrains must be tight.Therefore there are at most 2 untight constraints among the 2r − 2 constraints 0 ≤ y i ≤ p i , meaning there are at most 2 indices i, j such that p i = 0. We proceed by analyzing the possible cases:
• 0 < y i = p i and 0 < y j = p j .This case is not possible, since that would have implied r i=2 y i = r i=2 p i , contradicting (1).• 0 = y i < p i and 0 = y j < p j .This case is also not possible since that would have implied r i=2 y i = 0, contradicting the tightness of the last constraint in an optimal solution.
• 0 = y i < p i and 0 < y j = p j .Since all other p = 0, the other LP constraints become p i + p j = 1 0 + p j = y i + y j = α t (ip i + jp j ) Solving the two equations we obtain:
LP = 1 − αi t+αi−αj Q t−i+1 ≥ 1 − αi t+αi−αr Q t−i+1 = t−αr t+αi−αr Q t−i+1(2)
To use the induction hypothesis, we distinguish between two cases:
1. t − i + 1 ≥ αr, in which case it is thus sufficient to prove the following claim.
Claim 3.6.For every half-integer α ≥ 1 and integers r ≥ i ≥ 2 and t ≥ αr + i − 1, it holds
Q t−i+1,r,α Qt,r,α ≥ t+αi−αr t−αr . Proof. Recall that Q t = 2α+1 (r+1) t−α(r−2) 2α −1
and denote t = t − αr.Then
LHS = t +2α 2α t −i+2α+1 2α = (t + 2α) • • • (t + 1) (t + 2α − i + 1) • • • (t + 1 − i + 1) = (t + 2α) • • • (t + 2α − i + 2) t • • • (t − i + 2) = 1 + 2α t • • • 1 + 2α t − i + 2 ≥ 1 + 2α t i−1 ≥ 1 + 2α(i − 1) t ≥ 1 + αi t = RHS 2. t − i + 1 < αr, in which case Q t−i+1 = 1.
Here we get
LP ≥ 1 − αi t−αr+αi ≥ 1 − αi αi+1 = 1 αi+1 ≥ 1 αr+1 ≥ 2α+1 (r+1)( t−α(r−2) 2α ) = Q t ,
where the last inequality follows from the fact that t−α(r−2) ≥ αr+1−α(r−2) ≥ 2α+1.
• 0 < y i < p i and 0 = y j = p j .In this case p i = 1, y i = αi t , and therefore
LP = 1 − αi t Q t−i+1 ≥ 1 − αi t−α(r−i) Q t−i+1 ,
which is exactly as in (2) in the previous case.
Having bounded the value of the linear program, this completes the proof of Lemma 3.5.
Lower Bound
For completeness, we remark that at least for α > 1, the exponential dependence on r in Theorem 3.2 is indeed necessary.Consider a "sunflower" hypergraph on n = rm−m+1 vertices that consists of m hyperedges of size r, intersecting at a single vertex, supplemented with m two-uniform cliques of size r each -one for each of the hyperedges.Each of the r-hyperedges is given weight 1 and each of the two-edges is given weight α−1 2 r .The minimum cut value in this graph is 1, since every cut contains at least one of the r-hyperedges.However, all Ω(m • 2 r ) cuts given by the 2 r bipartitions of a single r-hyperedge, are of weight at most α.
Proof Of Theorem 3.1
Since the proof of Theorem 3.1 closely follows the proof in the original setting of graphs (cf.[BK02]), we refrain from repeating the full details.Instead, we choose to present an outline of the proof, emphasizing the key reasons it translates to the hypergraph setting, and handling the key differences, that require a separate treatment.
The main tool used by Benczúr and Karger is random sampling: each edge e is included in the sparsifier with probability p e , and given weight w e /p e if included.It is thus immediate that every cut in the sparsifier preserves its weight in expectation.The main task is thus to carefully select the sampling probabilities p e in order to both obtain the required number of edges in the sparsifier, and guarantee the required concentration bounds.
As a rough sketch, to guarantee concentration, one needs to apply a Chernoff bound to estimate the probability that a specific cut (which is a sum of the independent samples of the edges it contains) deviates from its expectation.Subsequently, a union bound over all cuts is used to show the concentration of all cuts.Yet a-priori it is unclear whether the Chernoff bound is strong enough to handle the exponentially many different cuts in the union bound.The remedy comes in the form of the bound on the the number of cuts of each weight given by Theorem 3.2.It is still unclear how should the random sampling be tuned to handle both the small and large cuts simultaneously.If we are to chose the sampling probability to be small enough to handle the exponentially many large cuts, we run into trouble of small cuts having large variance.On the other hand, increasing the sampling probability imposes a risk of ending up with too many edges in the sparsifier.
Following Benczúr and Karger, we now show that when no edge carries a large portion of the weight in any of the cuts, the cut-counting theorem is sufficient to obtain concentration.Theorem 3.7.Let H = (V, E, w) be a r-uniform hypergraph on n vertices, let ε > 0 be an error parameter, and fix d ≥ 1.If H = (V, E , w ) is a random subhypergraph of H where the weights w are independent random variables distributed arbitrarily (and not necessarily identically) in the interval [0, 1], and the expected weight of every cut in H exceeds ρ ε = 3 ε 2 (r + (d + 2) ln n), then with probability at least 1 − n −d , every cut in H has weight within (1 ± ε) of its expectation.
One can verify that the proof of a similar theorem for the case of graphs, as appears in [Kar99], translates to the hypergraph setting.For the sake of the proof, a cut is merely a sum of independently sampled edges/hyperedges.The lower bound on the weight of the minimum expected cut ŵ allows one to show that probability of a cut of weight α ŵ to deviate from its expectation is at most n −α(d+2) • e −αr which trades-off nicely with the bound on the number of cuts given by Theorem 3.2.
Informally, the latter theorem implies that in order to obtain the desired concentration bound in the general case, the sampling probability of an edge must be inversely proportional to the size of the largest cut that contains that edge.This motivates the following definitions, and the theorem that follows them.Definition 3.8.A hypergraph H is k-connected if the weight of each cut in H is at least k.Definition 3.9.A k-strong component of H is a maximal k-connected vertex-induced subhypergraph of H. Definition 3.10.The strong connectivity of hyperedge e, denoted k e , is the maximum value of k such that a k-strong component contains (all endpoints of ) e.
Note that one can compute the strong connectivities of all hyperedges in a hypergraph in polynomial time as follows.Compute the global minimum cut, and then proceed recursively into each of the two subhypergraphs induced by the minimum cut.The strong connectivity of an edge would then be the maximum among the minimum cuts of all the subhypergraphs it has been a part of throughout the recursion.The minimum cut in a hypergraph was shown to be computable in O(n 2 log n + mn) time by [KW96].Note that since the total number of subhypergraphs considered throughout the recursion is at most n, there are at most n different strong-connectivity values in any hypergraph.
Theorem 3.11.Let H be an r-uniform hypergraph, and let ε > 0 be an error parameter.Consider the hypergraph H ε obtained by sampling each hyperedge e in H independently with probability p e = 3((d+2) ln n+r) keε 2
, giving it weight 1/p e if included.Then with probability at least 1
− O(n −d ) 1. The hypergraph H ε has O n ε 2 (r + log n) edges. 2. Every cut in H ε has weight between (1 − ε) and (1 + ε) times its weight in H.
The proof of the theorem for the hypergraph setting is again completely identical to the proof in [BK02] (c.f., Theorem 2.6).The only thing that needs verifying is that strong-connectivity induces a recursive partitioning of the vertices of the hypergraph, just as it does when dealing with graphs.This is in fact the case, mainly because the components considered in the definitions are vertex-induced, and therefore the cardinality of the hyperedges plays no part.One can then decompose the hyperedges of the hypergraph to "layers", based on their strong-connectivity, and apply Theorem 3.7 to each layer separately.
To complete our discussion we bring the reader's attention to a couple of places where the cardinality of the hyperedges has played part:
• The modified parameter p e = 3(r+(d+3) ln n) keε 2 counters the number of cuts from Theorem 3.2 (at most O(2 αr n 2α ) cuts of weight α ŵ) and the number of distinct edge-connectivity values, which is at most n.9
• The number of edges in the sparsifier is (with high probability) O n ε 2 (r + log n) since the sampling probability is also linear in r.
SAT Sparsification
Lemma 3.12.Given an r-CNF formula Φ with n variables and m clauses, there exists an (r + 1)uniform hypergraph H with 2n + 1 vertices, and a mapping Π : {0, 1} n → {0, 1} 2n+1 from the set of all assignments to Φ to the set of all cuts in H, such that for every assignment ϕ, it holds that val Φ (ϕ) = val H (Π(Φ)).
Proof.Consider an r-CNF formula Φ with variables {x i } i∈ [n] .We construct the weighted hypergraph H whose vertices are {x i , ¬x i } i∈[n] and a special vertex F .For each clause i 1 ∨ i 2 ∨ • • • ∨ ir , we add a hyperedge { i 1 , i 2 , . . ., ir , F }.Moreover, let Π be the mapping that maps an assignment to Φ to the cut in H obtained by placing all vertices corresponding to true literals on one side, and the F vertex together with all vertices corresponding to false literals on the other side.
For an assignment ϕ to Φ, it is clear that a hyperedge is contained in the cut Π(ϕ) if and only if at least one of the vertices it contains is on the opposite side of F .Therefore the weight of Φ(ϕ) is exactly the value of ϕ.
Theorem 3.3 follows from Lemma 3.12 and Theorem 3.1.
Future Directions
Our results raise several questions that deserve further work.
Sketching Max-Cut.Our results and the results of [KKS14] make progress on the streaming complexity of approximating Max-Cut, showing polynomial space lower bounds.To fully resolve this problem, one still needs to determine whether Ω(n) space is necessary for any non-trivial approximation (i.e., strictly better than 1/2), or whether there is a sublinear-space streaming algorithm that beats the 1/2-approximation barrier.
Also of interest is the communication complexity of approximating Max-Cut in the multiround two-party model, and even a multi-round analogue of Boolean Hidden Hypermatching.
Sketching Cuts in Hypergraphs.Can one improve on the linear dependence on r in hypergraph sparsification (Theorem 3.1)?Or prove a matching lower bound?Such a refinement could be especially significant when the hyperedge cardinality is unbounded.
General CSPs.Do all CSPs admit sketches of bit-size o(n r ), or even Õ(n), that preserve the values of all assignments?From the other direction (lower bounds), we may even restrict ourselves to sketches that are sub-instances, and ask whether there are CSPs that require size Ω(nr) or even n Ω(r) ?
Lemma 2.5 ([YV11, Theorem 2.1]).The randomized one-way communication complexity of BHH t n
Proposition 2.7.Let G = (V, E A • ∪ E B ) be an input graph on |V | = n vertices.Let w A and w B be the maximum cut values in G A = (V, E A ) and G B = (V, E B ) respectively.Then it holds for the maximum cut value w in G 2 3
4 :
4
contract e by merging all its endpoints and removing self-loops 6 5: C ← random cut in H (bipartition of V (H )) 6: return the cut C in H induced by the cut C Theorem 3.4.Let H = (V, E, w) be a weighted r-uniform hypergraph with minimum cut value ŵ, let n = |V |, and let α ≥ 1 be some half-integer.Fix C = (S, V \ S) to be some cut in H of weight at most α ŵ.Then Algorithm 3.1 outputs the cut C with probability at least Qn,r,α
We use Õ(f ) to denote O(f polylog f ), which suppresses logarithmic terms.
Another possible definition, see [dCHS11, Corollary 7], is e∈E we • |e ∩ S| • |e ∩ S|. The latter definition seems technically easier for sparsification, although both generalize the case of ordinary graphs (r = 2).
For the proof of the lower bound it suffices to restrict our attention to unweighted graphs, with all edges having unit weight.
Since the cuts ( S, S) has the same value as (S, S), the vector xS can actually be ε-close to x, but by taking our code to have no codeword being close to the negation of another codeword we can always try decoding both xS and xS.
Throughout this work we allow r-uniform hypergraphs to contain also hyperedges with less than r endpoints (for instance by allowing duplicate vertices in the same hyperedge).
Here by self-loops we refer to hyperedges that contain only a single vertex. Note also that the cardinality of an edge can only decrease as a result of contractions.
Since not all iterations occur in all executions, it might be the case that no edge is contracted in iteration t. However, in that case iteration t is good, and hence by the induction hypothesis the claim holds.
Note that |e| refers to the edge's cardinality, whereas w(ei) refers to its weight.
In their analysis[BK02] take a union bound over n 2 distinct edge-connectivity values. For hypergraphs using the stronger linear bound (instead of the trivial n r ) is crucial.
AcknowledgementsWe thank Alexandr Andoni and David Woodruff for useful discussions at early stages of this work.* Work supported in part by a US-Israel BSF grant #2010418, Israel Science Foundation grant #897/13, and by the Citi Foundation.
Graph sparsification in the semi-streaming model. K J Ahn, S Guha, 10.1007/978-3-642-02930-1_27arXiv:0902.014036th International Colloquium on Automata, Languages and Programming: Part II, ICALP '09. Springer-Verlag2009
Analyzing graph structure via linear measurements. K J Ahn, S Guha, A Mcgregor, 10.1137/1.9781611973099.40Proceedings of the Twenty-third Annual ACM-SIAM Symposium on Discrete Algorithms, SODA '12. the Twenty-third Annual ACM-SIAM Symposium on Discrete Algorithms, SODA '12SIAM2012
Graph sketches: Sparsification, spanners, and subgraphs. K J Ahn, S Guha, A Mcgregor, 10.1145/2213556.2213560Proceedings of the 31st Symposium on Principles of Database Systems, PODS '12. the 31st Symposium on Principles of Database Systems, PODS '12New York, NY, USAACM2012
The sketching complexity of graph cuts. A Andoni, R Krauthgamer, D P Woodruff, arXiv:1403.70582014
Approximating s-t minimum cuts in Õ(n 2 ) time. A A Benczúr, D R Karger, 10.1145/237814.237827Proceedings of the Twenty-eighth Annual ACM Symposium on Theory of Computing, STOC '96. the Twenty-eighth Annual ACM Symposium on Theory of Computing, STOC '96New York, NY, USAACM1996
Randomized approximation schemes for cuts and flows in capacitated graphs. A A Benczúr, D R Karger, arXiv:cs/02070782002CoRR
Sparse sums of positive semidefinite matrices. M K De Carli Silva, N J A Harvey, C M Sato, arXiv:1107.00882011
On the structure of the system of minimum edge cuts in a graph. E A Dinitz, A V Karzanov, M V Lomonosov, Issledovaniya po Diskretnoi Optimizatsii. 1976
Satisfiability allows no nontrivial sparsification unless the polynomial-time hierarchy collapses. H Dell, D Van Melkebeek, 10.1145/1806689.1806725Proceedings of the Forty-second ACM Symposium on Theory of Computing, STOC '10. the Forty-second ACM Symposium on Theory of Computing, STOC '10New York, NY, USAACM2010
A Goel, M Kapralov, I Post, arXiv:1203.4900arXiv:1203.4900Single pass sparsification in the streaming model with edge deletions. 2012arXiv preprint
Improved approximation algorithms for maximum cut and satisfiability problems using semidefinite programming. M X Goemans, D P Williamson, 10.1145/227683.227684J. ACM. 426November 1995
P Indyk, A Mcgregor, I Newman, K Onak, Open questions in data streams, property testing, and related topics. 2011
Global min-cuts in RN C, and other ramifications of a simple min-cut algorithm. D R Karger, Proceedings of the Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, SODA '93. the Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, SODA '93Philadelphia, PA, USASociety for Industrial and Applied Mathematics1993
Random sampling in graph optimization problems. D R Karger, Stanford University. 1995PhD thesis
Better random sampling algorithms for flows in undirected graphs. D R Karger, Proceedings of the Ninth Annual ACM-SIAM Symposium on Discrete Algorithms, SODA '98. the Ninth Annual ACM-SIAM Symposium on Discrete Algorithms, SODA '98Philadelphia, PA, USASociety for Industrial and Applied Mathematics1998
Random sampling in cut, flow, and network design problems. D R Karger, 10.1287/moor.24.2.383Mathematics of Operations Research. 2421999
High dimensional expanders, ramanujan complexes and topological overlapping. T Kaufman, D Kazhdan, A Lubotzky, Proceedings of the 55th Annual IEEE Symposium on Foundations of Computer Science. the 55th Annual IEEE Symposium on Foundations of Computer Science2014To appear
Optimal inapproximability results for Max-Cut and other 2-variable CSPs?. S Khot, G Kindler, E Mossel, R O'donnell, 10.1109/FOCS.2004.4945th Annual IEEE Symposium on Foundations of Computer Science. IEEE2004
Streaming lower bounds for approximating MAX-CUT. M Kapralov, S Khanna, M Sudan, September 2014Manuscript
Single pass spectral sparsification in dynamic streams. M Kapralov, Y T Lee, C Musco, C Musco, A Sidford, arXiv:1407.1289KLM + 11. 2011
A Simple Hypergraph Min Cut Algorithm. R Klimmek, F Wagner, 1996Freie Universität Berlin, Fachbereich Mathematik / B. Freie Univ., Fachbereich Mathematik
Approximation algorithms for hypergraph small set expansion and small set vertex expansion. A Louis, Y Makarychev, arXiv:1404.45752014
Hypergraph Markov operators, eigenvalues and approximation algorithms. A Louis, arXiv:1408.24252014
Lower bound of network reliability. M V Lomonosov, V Polesskii, Problemy Peredachi Informatsii. 821972
Graph stream algorithms: A survey. A Mcgregor, 10.1145/2627692.2627694SIGMOD Rec. 431May 2014
On multiplicative λ-approximations and some geometric applications. I Newman, Y Rabinovich, 10.1137/100801809SIAM Journal on Computing. 4232013
Cyber security analysis of power networks by hypergraph cut algorithms. Y Yamaguchi, A Ogawa, A Takeda, S Iwata, Proceedings of the Fifth Annual IEEE International Conference on Smart Grid Communications. the Fifth Annual IEEE International Conference on Smart Grid Communications2014To appear
The streaming complexity of cycle counting, sorting by reversals, and other problems. W Yu, E Verbin, 10.1137/1.9781611973082.2Proceedings of the Twenty-Second Annual ACM-SIAM Symposium on Discrete Algorithms. the Twenty-Second Annual ACM-SIAM Symposium on Discrete Algorithms2011
Algorithms for Streaming Graphs. M Zelke, Südwestdeutscher Verlag für Hochschulschriften. 2009Mathematisch-Naturwissenschaftliche Fakultät II, Humboldt-Universität zu BerlinPhD thesis
Intractability of min-and max-cut in streaming graphs. M Zelke, 10.1016/j.ipl.2010.10.017Inf. Process. Lett. 1113January 2011
A survey on streaming algorithms for massive graphs. J Zhang, 10.1007/978-1-4419-6045-0_13Managing and Mining Graph Data. C C Aggarwal, H Wang, Springer201040
| [
-0.12097112089395523,
-0.07643047720193863,
0.005749342031776905,
-0.015724672004580498,
0.12053745239973068,
-0.07782796025276184,
-0.10149803757667542,
-0.011148587800562382,
0.05562952905893326,
0.09996537864208221,
-0.1186949759721756,
-0.03184711933135986,
0.025424780324101448,
0.0910... |
12.5 gm.; white cell count, 8400. The urine spe cific gravity was 1.020; no albumin or significant formed elements were found. The nonprotein nitrogen was 16 mg., and the total protein 7.5 gm.
Roentgenograms of the chest dem onstrated a well-circumscribed area of increased density at the apex of the left lower lobe, measuring about 8 by 8 by 10 cm. There was no degen@ra tion within it. The remainder of the lung parenchyma was clear. Intra venous and retrograde pyelography showed a deformity of the calyxes and pelvis on the right, with dilatation of the superior and inferior calyxes. The left kidney pelvis was normal. Both kidney shadows were of normal size.
A bronchoscopy demonstrated no abnormalities.
A smear taken from the dorsal division of the left upper-lobe bronchus was negative for tumor cells.
In smears takenfromtheleft lower lobe bronchus, a few acid-fast bacilli were found. Needle aspiration of the chest lesion was unsuccessful.
During the first ten hospital days, the patient's course was not remarkable.
She was afebrile. On the eleventh hospital day an operation was performed.
I)i1f@r@ntinI Diugnouiu
DR. MERRILL SOSMAN (Radiologist,
Peter Bent Brigham Hospital): I think it is fair, inasmuch as the patient was admitted because of a roentgenogra phical finding from a chest clinic, to start with the films and then work back to the history, physical examination, and laboratory findings.
We can see in this film that this is the chest of a young woman. She has a single lesion in the left mid-chest, measuring 8 cm. in diameter and. not very sharply outlined. In the lateral view, lying well back posteriorly in the A 41-year-old woman was admitted to the hospital from a chest clinic be cause of a lesion in the left chest.
The patient was well until three months before admission, when she contracted an upper respiratory infec tion with coryza, hoarseness, and a cough productive of half @icup of brownish-gray sputum a day. The cough and sputum production sub sided, but hoarseness continued, and increasing dyspnea, rapid breathing, occasional â€oe¿ choking― spells, and wheez ing respiration followed. There had been a 15-pound weight loss in four months, despite an excellent appetite, and progressive weakness. The latter was intermittent, accompanied by pro fuse sweating and a feeling of immi nent blackout.
For three weeks she had soreness in the left chest. When she was eighteen, she had a spot on the right lung, which cleared after a year of bed rest. Eleven years before admis sion, a right nephrostomy for renal cal culi was performed. Three years before entry, a total hysterectomy and right salpingo-oophorectomy were per formed at this hospital for vaginal bleeding.
The pathological diagnosis was tubal pregnancy. Two years before entry, a neighbor with whom she ‘¿ had had contact developed tuberculosis. For that reason, a chest roentgenogram was taken at that time. It was reported to be normal.
Physical examination revealed a woman who appeared chronically ill. The fingernails showed moderate club 1)mg. There were tenderness on pres sure over the left chest, anteriorly and posteriorly, and dullness over the left base posteriorly, with decreased left diaphragmatic excursion. The blood pressure was 140 systolic,
CANCER CLINICS
previously. Most importantofallisthe findingof acid-fast bacilli in smears taken from the left lower-lobe bron chus. If that is reliable, which it cer tainly should be, we are forced to make a diagnosis of tuberculosis somewhere in the respiratory tract and presumably in the left lower lobe because that is wherethesmears wereobtained. Were there any sputum examinations made? I did not notice anything about that in the report.
DR. LAMAR SOUTTER: The sputum
was negative for acid-fast organisms.
DR. SOSMAN: So this is an isolated
finding on bronchoscopic examination.
We mustmakeadiagnosis ofpulmonary tuberculosisâ€"postulating the ulcer ating tracheobronchial type of tubercu losisâ€"and then try to decide whether this shadow that we see can also be explained on the basis of pulmonary tuberculosis.
It is a very rare type of shadow to be produced by tuberculo sis in my experience. It is peripheral, which tuberculosis usually is, but it is round and smooth and homogeneous in density, and there is no evidence of cavity or any calcification in it. One of the most important things against it, I think, is the statement that she was afebrile.
So we have to consider strongly the possibility that this was @a separate lesion and not due to the pre sumed tuberculosis. Another sugges tion in the history is the operation on the kidney some years before admis sion, and we have here a series of renal studies, both intravenous and retro grade pyelograms, all of which show a definite deformity of the right renal pelvis, which I think can readily be seen. It is quite possible, in fact quite probable, that this deformity is merely the result of previous operation and not of any intrinsic disease in the kid ney at present. We notice that there is dilatation of the superior and inferior calyxes, with a rather contracted cen tral portion of the pelvis. The opposite renal pelvis on the left fills well except on one small film, where there is a chest, the shadow is shaped a good deal like a gumdrop, the flat part being against the posterior chest wall and the anterior surface being sharply rounded or convex. The other findings in the chest appear perfectly normal. The heart is not displaced; the diaphragm is in normal position; the ribs are in tact. The trachea appears normal, and all the visible bones appear normal.
Our problem then is to try to find out the nature of this circular mass in the left chest posteriorly, which is in the approximate region of the apex of the lower lobe. Going back to the his tory, we find a great many â€oe¿ red her rings― dragged across the trail. The history says that she had a negative roentgenographic examination two years before admission following ex posure to a patient with tuberculosis. If that is reliable, it certainly would rule out both the congenital group of tumors and the benign tumors. If it was a tumor, it would have had to be malignant to reach this size in two years. Do we know where the roent genographic examination was done? The one, thing brought up more than anything else in the history is the story of tuber culosis. She is said to have had â€oe¿ a spot on the right lung― at the age of 18 years. There is no evidence of that at present. She had contact with a patient who was known to have tuberculosis, and this was the cause of her roent genographic examination two years suggestion of a negative shadow in the renal pelvis. Itdoesnotpersist so I think we candisregard that.
The hysterectomy and salpingo oophorectomy are readily explained by the tubal pregnancy and had nothing to do with the mass in the chest, par ticularly in this interval of timeâ€"three years.
Going back to the physical examina tion we note clubbing of the fingers. How can we tie that up with the mass that we find described in the history andatphysical examination? Clubbing in my experience is most common in congenital heart disease. This patient had no murmurs or signs of heart dis ease. When patients have clubbing from heart disease they usually have murmurs, cyanosis, and polycythemia due to the long-continued shunt of blood. The second most common cause of clubbing is primary tumor of the lung, which is nearly always malig nant. Chronic infection of the lung is a third cause of clubbing of the fingers in my experience, and this, of course, can be a tuberculoma or a tu. berculous area at the apex of the lower lobe. But, in my limited experience, clubbing in tuberculosis is usually found only in the far-advanced case with cavitation and secondary infec tion. I would expect it to be quite rare in a lesion of such short duration as this. A fourth cause of clubbing is polyposis of the intestine, which is very rare indeed. There is no gastrointes tinal examination here so we cannot consider that.
That about covers my discussion ex cept to say that I cannot explain the dyspnea, the rapid breathing, the chok ing spells, and wheezing respirations noted earlier in the history. The hoarse ness continued, and it is quite possible that it was due to tuberculosis of the larynx. This would tie up both things on one foundation. But I presume that the larynx was inspected at the time of bronchoscopy. So, to sum up this short and very easy case, I may say we are forced to make a' diagnosis of pulmonary tuber culosis because of the positive sputum. I would like to tie up the chest lesion with tuberculosis also and call it tuber culoma. If so, one ought to see a large area of consolidation or perhaps atelec tasis due to the tuberculosis of the ulcerating tracheobronchial type. But I suspect that there was a separate pri mary tumor of the lung in addition. Regarding the type of tumor, it is pure speculation in my experience to try to guess the kind of tumor a given patient has unless it has some of the character istic findings, which this patient did not have. If we want to play poker, which I think is legal in this type of exercise, we may guess that it was non malignant because it was located oppo site the seventh rib, and yet the ribs resected were the fifth and sixth, leav ing the seventh rib intact, which puzzles me a little bit. If it were a malignant tumor invading the chest wall, I would assume that a good sur geon would excise the whole area in cluding the seventh rib. Is that legal? woman. We made a tentative preoper ative diagnosis of bronchogenic car cinoma. This was before the report of the bronchoscopic smears was re ceived on the ward. The incision was made through the bed of the fifth rib to enable us to get above where the tumor was adherent to the chest wall. The tumor was adherent over the sixth rib. If one looks at the postoperative film, one sees the area of absent rib where the tumor was adherent.
The appearance of the tumor suggested ma lignancy. It protruded from the lung tissue and seemed to invade the chest wall. We did a left lower lobectomy, going extrapleurally, and afterward re sected that part of the chest wall to which the tumor had been adherent.
Dn. SOSMAN: That is rather surpris ing; the sixth rib is at the upper edge of the shadow. The center of the tumor is opposite the seven rib posteriorly.
Dn. SOUTTER: The tumor was adher ent to the chest wall at its apex and not at its center.
DR. MALLORY: The lobe that was re
sected showed a large spherical area of epidermoid carcinoma near the apex. We searched very carefully and were not able to find any trace of tubercu losis. I have no explanation for the acid-fast bacilli. I would hate to sug gest the bronchoscope.
DR. BENEDICT:
Of course it is pos sible there was tuberculosis in the other lobe that we knew nothing about. I was as much surprised as anyone when tubercle bacilli were found. There must have been a mistake somewhere.
DR. MALLORY:
We must remember that acid-fast bacilli do not always mean tuberculosis, although in the spu tum the chance of anything else is so slight that we feel safe in neglecting any other possibility. But we have no real knowledge that they were tubercie bacilli.
DR. ALLEN G. BRAILEY: Where did the tumor arise?
DR. MALLORY:
From one of the sec ondary bronchi running to the apex of the lower lobe. It was completely oc cluded and surrounded by tumor, and the bronchus leading still higher up was compressed by the mass. The re gional lymph nodes were normal. Tu mor cells were found in the parietal pleura after it was resected.
DR. BENEDICT:
The bronchoscopy was negative, as you know, but I would like to point out that in that area bronchoscopy probably would be nega tive for carcinoma. We would not be able to reach a tumor in the apex of the left lower lobe. In a series of 309 cases of proved carcinoma broncho scoped by me in this hospital, there were positive biopsies in 61 per ‘¿ cent. Gibbon and his associates (I. Thoracic Surg. 17:419-427, 1948) in Pennsyl vania have had positive cytological studies from bronchoscopic washings in 89 per cent of 105 cases studied. Our figures are not so good on bron choscopic washings, nor have we done as many. I would say carcinoma was definitely not ruled out at this exam ination. We have had a few cases with both tuberculosis and carcinoma.
DR. TRACY B. MALLORY: It was done in one of the state sanatoriums. DR. SOSMAN: Then it should be re liable. One other thing that we should note in evaluating the shadow is whether or not it was movable with the lung. Do you know whether the patient was fluoroscoped? DR. JOSEPH HANELIN: No. I am not familiar with the case. DR. S0SMAN: It might make a differ ence if it were attached to the chest wall or free in the lung and moved up with cough or expiration.
DR. EDWARD B. BENEDICT: That is right.DR. SOSMAN: And nothing
abnormal
was seen.
DR.
BENEDICT:
The
l)ronchoscopy
was negative.
DR. SOSMAN:
If there
was
enough
tuberculosis to cause hoarseness, either
thickening
or reddening
should have
been visible on the vocal cords.
A PHYSICIAN: Was a Papanicolaou stain done?DR.
MALLORY:
Yes,
and
it was
negative.
| [
-0.034177061170339584,
0.07007643580436707,
-0.025447307154536247,
-0.10619060695171356,
-0.14167216420173645,
-0.13453155755996704,
0.023108066990971565,
0.18905699253082275,
0.09256285429000854,
-0.0018327459692955017,
0.0028433706611394882,
0.08081643283367157,
0.1775307059288025,
0.078... |
The 6dF Galaxy Survey: a low-redshift benchmark for bulge-dominated galaxies
5 Jan 2008
Matthew Colless colless@aao.gov.au
Anglo-Australian Observatory
EppingNSWAustralia
Heath Jones
Anglo-Australian Observatory
EppingNSWAustralia
Rob Proctor
Centre for Astrophysics and Supercomputing
Swinburne University of Technology
HawthornVICAustralia
Craig Harrison
Anglo-Australian Observatory
EppingNSWAustralia
Research School of Astronomy and Astrophysics
ACT
Australian National University
Weston CreekAustralia
Lachlan Campbell
Anglo-Australian Observatory
EppingNSWAustralia
Research School of Astronomy and Astrophysics
ACT
Australian National University
Weston CreekAustralia
Philip Lah
Research School of Astronomy and Astrophysics
ACT
Australian National University
Weston CreekAustralia
The 6dF Galaxy Survey: a low-redshift benchmark for bulge-dominated galaxies
5 Jan 20084F234F1FD0C678BEC6DA60F8AE83B170arXiv:0801.0811v1[astro-ph]galaxies: bulgesgalaxies: stellar contentgalaxies: abundances
The 6dF Galaxy Survey provides a very large sample of galaxies with reliable measurements of Lick line indices and velocity dispersions.This sample can be used to explore the correlations between mass and stellar population parameters such as age, metallicity and [α/Fe].Preliminary results from such an analysis are presented here, and show that age and metallicity are significantly anti-correlated for both passive and star-forming galaxies.Passive galaxies have strong correlations between mass and metallicity and between age and α-element over-abundance, which combine to produce a downsizing relation between age and mass.For old passive galaxies, the different trends of M/L with mass and luminosity in different passbands result from the differential effect of the mass-metallicity relation on the luminosities in each passband.Future work with this sample will examine the Fundamental Plane of bulge-dominated galaxies and the influence of environment on relations between stellar population parameters and mass.
The 6dF Galaxy Survey
The 6dF Galaxy Survey (6dFGS; www.aao.gov.au/local/www/6df;Jones et al. 2004Jones et al. , 2005) ) is a redshift and peculiar velocity survey of galaxies in the local universe.The observations for the survey were obtained during 2001-2006 using the UK Schmidt Telescope and the 6dF spectrograph (Watson et al. 1998).The 6dFGS covers 92% of the southern sky with |b| > 10 • .Its primary sample is drawn from the 2MASS Extended Source Catalog (XSC; Jarrett et al. 2000) and consists of galaxies with K tot < 12.65; for this sample the redshift completeness is 88%.It also includes secondary samples complete down to H < 12.95, J < 13.75 (from the 2MASS XSC) and r F < 15.6, b J < 16.75 (from the SuperCosmos Sky Survey; Hambly et al. 2001).The 6dFGS peculiar velocity survey uses the Fundamental Plane relation to derive distances and velocities for about 15,000 bright early-type galaxies.The 6dFGS database comprises 137k spectra and 124k galaxy redshifts, plus photometry and images.The final data release will be made public in August 2007 (Jones et al. in prep.; see www-wfau.roe.ac.uk/6dfgs).
As well as its intended purpose as a survey of the structure and motions in the local universe, the 6dFGS also provides a benchmark sample for studying the properties of the low-redshift galaxy population.Here we present some preliminary results from an analysis of the stellar populations in a sample of about 6000 galaxies with high-quality spectra from the 6dFGS Second Data Release (DR2; Jones et al. 2005).Velocity dispersions (σ)
Figure 1.The distribution of age and metallicity for the passive galaxies (left) and the emission-line galaxies (right).Galaxies classified as AGN on the basis of their emission line ratios are shown as grey dots in the right-hand panel.The mean uncertainties in the estimates of age and metallicity are shown by the error bars in the bottom left corner of each panel.
have been measured for these galaxies using the cross-correlation technique of Tonry & Davis (1979).Comparisons with other high-quality samples show good agreement and imply the 6dFGS dispersions have a median error of 10.9% (Campbell et al., in prep.).
Stellar population parameters and relations
Stellar population parameters for these galaxies have been derived from Lick index measurements for approximately 15 indices covering the spectral range 4000-5500 Å (Proctor et al., in prep.).Ages, metallicities and α-element over-abundances were determined by comparing these index measurements to the simple stellar population models of Korn, Maraston & Thomas (2005) using the χ 2 -fitting method introduced by Proctor & Sansom (2002).The method rejects those indices that give poor fits to the models, and this excludes Hβ for galaxies both with and without Hα emission.For passive galaxies without Hα emission, the uncertainties in the derived ages are typically about 0.17 dex in age, 0.15 dex in [Z/H] and 0.10 dex in [α/Fe].For galaxies that do show significant Hα emission, the fits also reject Hγ and Hδ, which results in somewhat larger uncertainties.
The distribution of age and metallicity is shown in Figure 1 both for passive galaxies (those with no detected Hα emission) and for star-forming galaxies (those in which Hα emission is detected).In general, the passive galaxies have metallicities in the range [Z/H]=−0.3-0.5 and luminosity-weighted ages of 3-14 Gyr, while the star-forming galaxies have solar or higher metallicities and ages less than 3 Gyr.Both samples show a trend of increasing metallicity for younger galaxies that is substantially stronger than the residual correlation between the errors in age and metallicity.
If we just consider the passive galaxies, then as well as the correlation between age and metallicity, there are also correlations between metallicity and velocity dispersion and between age and [α/Fe], as shown in the left and middle panels of Figure 2: more massive galaxies tend to have higher metallicities, while older galaxies tend to have larger The 6dF Galaxy Survey α-element over-abundances.There is also a downsizing relation between age and velocity dispersion, in which the age of the youngest galaxies decreases with decreasing velocity dispersion, as indicated in the right panel of Figure 2.This latter relation would appear to be the projection in the age-log σ plane of the [Z/H]-log σ and age-[α/Fe] relations.
Age and metallicity effects on M/L
It is interesting to examine the effects of age and metallicity on the mass-to-light ratios for galaxies in different passbands.If we consider only old galaxies (greater than 10 Gyr), then the left panel of Figure 3 shows the trends of M/L in the B, R and K bands against both dynamical mass and K-band luminosity.Two points are worth noting: (i) the trends with dynamical mass are steeper than those with luminosity in all passbands, and (ii) the trends with both mass and luminosity are steeper in bluer passbands.
As well as eliminating age effects by selecting only old galaxies, we can also attempt to remove the dependence on metallicity in these relations.The right panel of Figure 3 shows as thick solid lines the same binned relations as in the left panel; it also shows these relations after correcting the mass-to-light ratio for differences in metallicity (dashed lines).These corrections are determined from the luminosities predicted by Bruzual & Charlot (2003) models for stellar populations having the metallicity (based on the mass-metallicity relation) and age of each mass or luminosity bin, and converting to the predicted luminosity for a stellar population with the same metallicity as the highest mass or luminosity bin.The corrected mass-to-light ratios resulting from this procedure have almost identical dependences on mass or luminosity, regardless of passband, as can be seen by comparing the dashed lines in the right panel of Figure 3 with the thin solid lines (which are just the corrected relations for the K-band).Thus the variations of M/L with passband for this sample of old galaxies can be fully accounted for by the massmetallicity relation.It is worth noting that the correction has almost no effect in the K-band, underlining the minimal impact of metallicity on K-band luminosities and the usefulness of this passband for studies of M/L and the Fundamental Plane.
Conclusions
The 6dFGS provides a large sample of galaxies with spectra of sufficiently high quality and spectral range to allow reliable measurements of both line indices and velocity dispersions.This sample can be used to explore the correlations between mass, age, metallicity and [α/Fe].Some preliminary results from such an analysis are presented here; a more detailed study will appear in Proctor et al. (2007, in prep).
We find that age and metallicity are significantly anti-correlated (younger galaxies are more metal-rich) for both passive and star-forming samples.Passive galaxies show the well-known strong correlation between mass and metallicity (more massive galaxies are more metal-rich), but also a strong correlation between age and α-element overabundance (older galaxies have higher over-abundances).These two effects combine to produce a downsizing relation between age and mass, such that the age of the youngest galaxies decreases with decreasing mass.For old (>10 Gyr) passive galaxies, the different trends of M/L with mass and luminosity in different passbands result from the differential effect of the mass-metallicity relation on the luminosities in each passband.
Future work will examine the Fundamental Plane of bulge-dominated galaxies and the influence of environment on relations between stellar population parameters and mass.
3
Figure 2 .
2
Figure 2.For passive galaxies there are strong correlations between metallicity and velocity dispersion (left panel) and between age and [alpha/Fe] (middle panel); there is also a downsizing relation between age and velocity dispersion (right panel).
Figure 3 .
3
Figure 3.At left, the dynamical mass-to-light (M/L) ratios of old galaxies (age >10 Gyr) in B, R and K bands is plotted against dynamical mass and K-band luminosity.Solid lines are means in five bins along the x-axis; the rms scatter is indicated by dashed lines.The average error on individual points is shown at the bottom right of each panel.At right, the mean M/L ratios are shown before (solid line) and after (dashed line) correction for the effect of the mass-metallicity relation on the luminosity.The thin solid lines in each panel show the K-band relation for the purposes of comparison.
AcknowledgementsWe acknowledge the contributions to this research program of the UKST observers and the entire 6dFGS team (www.aao.gov.au/local/www/6df/6dFGSteam.html).
. G Bruzual, S Charlot, MNRAS. 34410002003
. N C Hambly, H T Macgillivray, M A Read, MNRAS. 32612952001
. T H Jarrett, T Chester, R Cutri, AJ. 11924982000
. D H Jones, W Saunders, M Colless, MNRAS. 3557472004
. D H Jones, W Saunders, M Read, M Colless, PASA. 222772005
. A J Korn, C Maraston, D Thomas, A&A. 4386852005
. R N Proctor, A E Sansom, SPIE. 33558341998
. F G Watson, Q A Parker, S Miziarski, 1998SPIE3355834
| [
-0.1404457688331604,
-0.0721939206123352,
0.010016806423664093,
0.17796485126018524,
0.061141252517700195,
0.009548130445182323,
-0.15959432721138,
0.11163664609193802,
-0.06559918075799942,
0.006039023865014315,
-0.06683748960494995,
-0.22749006748199463,
0.09174314141273499,
-0.121595591... |
Evaluation of Knowledge, Attitude, Practice and Hospital Experience Regarding COVID-19 among Post-partum Mothers at a Tertiary Care Center: A Cross-sectional Study
Adhikari Sp
KATHMANDU UNIVERSITY MEDICAL JOURNAL
Pariyar J
KATHMANDU UNIVERSITY MEDICAL JOURNAL
Sapkota K
KATHMANDU UNIVERSITY MEDICAL JOURNAL
Gurung Tk
KATHMANDU UNIVERSITY MEDICAL JOURNAL
Adhikari Sr
KATHMANDU UNIVERSITY MEDICAL JOURNAL
Evaluation of Knowledge, Attitude, Practice and Hospital Experience Regarding COVID-19 among Post-partum Mothers at a Tertiary Care Center: A Cross-sectional Study
Page 10
BackgroundPregnant and breastfeeding women are more susceptible to viral infection and in the year 2020 they have to face the COVID-19 pandemic. Since, no successful treatment and vaccine has been developed so far, efforts to enhance the knowledge, attitudes, and practice of the public, especially the high-risk groups like pregnancy and postpartum period are crucial to manage COVID-19 pandemic.ObjectiveTo analyze the knowledge, attitude, practice and hospital experience regarding COVID-19 among post-partum mothers at a tertiary care center of NepalMethodThe data collection was based on direct interview after receiving written consent from the research participants, using a semi-structured questionnaire. The questionnaire consisted of 4 major domains-knowledge (8 questions), attitude (6 questions), practice (5 questions) and experience (5 questions). Standard descriptive statistics were used for the data, mean and standard deviation for continuous variables whereas frequencies and percentages for categorical variables.ResultA total of 203 post-partum women participated in the study. Almost all the participants had heard about COVID-19 (96.6%). A majority of them were aware about how COVID-19 gets transmitted and its preventive measures. Most of the participants (88.2%) knew that COVID-19 has effects on pregnancy. Almost all of participants (97%) wore mask during hospital stay. All of the women washed their hands with soap water or alcohol based sanitizer. A majority of the mothers (79.3%) wore mask while breastfeeding their baby.ConclusionThe post-partum mothers have good knowledge, attitude, practice and experiences regarding the COVID-19 pandemic.
INTRODUCTION
The novel corona virus, COVID-19, a disease caused by SARS-CoV-2 has become a significant global health problem. With the number of infected cases and affected countries escalating rapidly, on March 11, 2020, the World Health Organization (WHO) declared COVID-19 a pandemic. 1 Although majority of people are asymptomatic, individuals with confirmed SARS-CoV-2 develop clinical symptoms of fever, cough, and shortness of breath. 2 Pregnant and postpartum women are considered high-risk group and deserve our great attention because of the physiological changes during pregnancy and an associated immunocompromized state that make them more susceptible to virus. Good knowledge is a prerequisite for overall practice of preventive measures aimed to reduce the disease burden, forming positive attitude and promoting positive practice to disease. 3,4 In the year 2020, pregnant and breastfeeding women have to face the COVID-19 pandemic, and associated quarantine and isolation measures that have disturbed their private and professional lives. 5 Since, no successful treatment and vaccine has been reported so far, efforts to enhance the knowledge, attitudes, and practice of the public, especially the high-risk groups like pregnancy and post-partum period, are crucial to manage COVID-19 pandemic. 3 This study aims to assess knowledge, attitude, and practice (KAP) towards COVID-19 among the post-partum mothers that had delivered at a tertiary care center at Bharatpur, Chitwan and describe their experience during hospital admission.
METHODS
This was a single center, cross sectional survey conducted among all the post-partum mothers admitted in the postnatal ward of Bharatpur Hospital, Chitwan from 15 Chaitra -25 Chaitra 2076 (28 March -5 April, 2020). Bharatpur Hospital is a tertiary care and referral center located in central region of Nepal, which conducts approximately 12500 deliveries per year (based on labor room audit), and is also a designated hospital for management of COVID-19 patients. Pregnant women, admitted in the hospital with matching symptoms for COVID-19 were categorized as suspects and managed in a separate unit. Positive cases were then referred to COVID designated isolation ward and managed accordingly following appropriate protocol.
This study was approved by Institutional Review Committee (IRC), Bharatpur Hospital. The data collection was based on face-to-face interview by doctors/nurses after receiving written consent from the research participants, using a semi-structured questionnaire. The questionnaire consisted of 4 major domains-Knowledge (8 questions), Attitude (6 questions), Practice (5 questions) and Experience at the hospital (5 questions). The interviewers clarified the participants if they had any queries regarding the questions during the interview process and collected their responses on the proforma. SPSS version 25 was used for statistical analysis. Standard descriptive statistics were used for the data, mean and standard deviation for continuous variables whereas frequencies and percentages for categorical variables. The questions pertaining to the four domains (Knowledge, Attitude, Practice and Hospital experience) were described as frequencies and percentages.
RESULTS
A total of 203 post-partum women (median age: 25 years (range: 15 -40 years) participated in the study. Among them, 136 (67.0%) had normal vaginal delivery whereas the remaining 33.0% had cesarean delivery.
Almost all the participants had heard about COVID-19 (96.6%). The most frequent source of information was television and radio (81.8%) followed by internet and social media (63.5%). 90.1% of the participants knew that the causative agent of COVID-19 was a virus. A majority of them were aware about how COVID-19 gets transmitted, its clinical features and preventive measures. Most of the participants (88.2%) knew that COVID-19 has effect on pregnancy and 79.8% thought that the disease can be transmitted from mother to baby (Table 1).
Around three-quarters of the participants were worried about getting COVID-19 infection during delivery. Almost all the participants (98.5%) agreed that lock down will help in reducing spread and prevention of COVID-19 and it should be further added (Table 2).
Ninety-seven percent of participants wore mask during hospital stay, the commonest being a cloth mask. Very few women (2.5%) used an N95 mask. All of the women washed their hands with soap water or alcohol based sanitizer after contact with objects, but some of them did not wash hands before and after breast feeding (2.5%). A majority of the mothers (79.3%) wore mask while breastfeeding their baby.
Only 40.9% of participants were asked about the clinical features of COVID-19 during admission. Body temperature measurement by a digital thermometer was done in 21.7% of the participants. According to the experience of the participants, only 27.6% of health workers examined them wearing by PPE whereas only 30% recalled that their deliveries were conducted wearing PPE by health care workers.
DISCUSSION
COVID-19 is an emerging respiratory disease caused by a single-stranded, positive-sense ribonucleic acid (RNA) virus. The first case of COVID-19 was identified in Nepal on 7 The difference existed because of the structure of questionnaire used, with our study including very basic questions tailored to general population compared to the questions used in aforementioned study. Besides, that study used Multiple Choice Questions (MCQs) to determine knowledge, which we did not use. The major source of the information was television and radio followed by telephone conversation and social media. This reflected the strength and utility of internet and social media in dissemination of information regarding a pandemic, if properly utilized. 79.9% postpartum mother believed that COVID-19 infection transmit form mother to baby. The comprehensive literature search conducted by Zaigham et al. stated that vertical transmission of COVID-19 was 1 in 75 neonates who were born from COVID-19 infected mothers. 8 More than two thirds of the participants were worried about being affected from COVID-19 and uncertainty regarding delivery plan and place. This might be one of the factors for peripartum depression. In the Lancet Global Health, KC et al. and colleagues reported their prospective observational study on intrapartum care, stillbirth and neonatal mortality among 9 referral Hospitals from January to May, 2020. The number of institutional births had decreased by about 52.4% and the quality of care in the hospitals was compromised compared to scenario before lock-down. Neonatal deaths had also increased during lock-down. 9 Majority of the participants used face masks while in the hospital, mainly cloth masks. Although good quality evidence is lacking, some data suggest that cloth masks may be only marginally (15%) less effective than surgical masks in blocking emission of particles, and fivefold more effective than not wearing masks. Use of mask in healthcare settings is clearly essential to protect frontline workers, whereas the evidence supporting masks in nonclinical settings is both limited and of variable quality. Mass manufacture and use of cloth mask is cheap, and even facilitate economic activity. 12
Almost all the participants followed proper hand hygiene after contact with objects or during breast-feeding. Jordan et al. reported that hand washing and rubbing hand with alcohol-based sanitizer is the simplest and most effective ways to prevent the spread of respiratory infections like COVID-19. 13 Furthermore, increasing the availability of hand washing stations and alcohol-based hand rubbing is extremely beneficial and reduces transmission. 13 This study was conducted in one of the government hospitals that provides a big chunk of maternity service outside Kathmandu valley. The study has shown that KAP of the post-partum mothers were satisfactory, which is extremely good considering the current circumstances. Informative sessions on updates regarding COVID-19 will be highly beneficial that will help ameliorate stress/anxiety among these women and improve adherence to safe practices.
CONCLUSION
The post-partum mothers have good knowledge about the COVID-19 pandemic. Their attitude, practice and experiences were good enough to keep them and their neonates safe from COVID-19 infection. The study was conducted on limited time period so the number of study population was also small and it is recommended to conduct.
Table 1 .
1Distribution of Knowledge related characteristics regarding COVID-19 (n = 203)Knowledge domain
Frequency Percentage
1. Heard of COVID-19
Yes
196
96.6
No
7
3.4
2. Source of information
Television and Radio
166
81.8
Telephone and Mobile communication
alert
129
63.5
Internet and social media (facebook)
129
63.5
Newspaper
38
18.7
Friends and Family
88
43.3
3. Causative Agent
Virus
183
90.1
Don't know
20
9.9
4. Modes of transmission
Direct contact with infected person
178
87.7
Respiratory Droplet
170
83.7
Airborne Disease
65
32
Contact with contaminated surfaces or
objects
73
36
Contact with person with travel history to
COVID-19 circulating country
68
33.5
5. Clinical Features
Fever
196
96.6
Cough
190
93.6
Shortness of Breath
127
62.6
Headache
97
47.8
Myalgia
44
21.7
6. Preventive measures
Clean hand with soap and water, or alcohol
based hand sanitizer
194
95.6
Cover nose and mouth with coughing or
sneezing with tissue or a flexed elbow
174
85.7
Avoid close contact with anyone with a
cold or flu-like symptoms
114
56.5
7. Does COVID-19 affect pregnancy?
Yes
179
88.2
No
23
11.3
Don't know
01
0.5
8. Is COVID-19 transmitted from mother
to baby?
Yes
162
79.8
No
40
19.7
Don't know
01
0.5
Table 2 .
2Distribution of Attitude related characteristics regarding COVID-19Attitude domain
Frequency Percentage
1. Worried of getting COVID-19 infection
Yes
144
70.9
No
59
29.1
2. Worried about Delivery Plan and Place
Yes
149
73.4
No
54
26.6
3. Lock Down by Government will help
in reducing spread and prevention of
COVID-19
Yes
200
98.5
No
3
1.5
4. Government should add another Lock
Down
Yes
200
98.5
No
3
1.5
5. Awareness programme helps in practice
of public to prevent COVID-19 infection
Yes
201
99.1
No
2
0.9
6. Government should give surgical mask
to public
Yes
188
92.6
No
15
7.4
Table 3 .
3Distribution of Practice related characteristics
regarding COVID-19
Practice domain
Frequency Percentage
1. Wear mask during hospital stay
Yes
197
97.0
No
6
3.0
2. If yes, which Mask
Cloth
182
89.9
Surgical
10
4.9
N95
5
2.5
3. Wash hand with soap water or alcohol
based sanitizer after contact with objects
Yes
203
100.0
No
0
0.0
4. Wash hand with soap water before and
after breast feeding
Yes
198
97.5
No
5
2.5
5. Wear mask while breast feeding
Yes
161
79.3
No
42
20.7
A study byDavanzo et al. concluded that proper hand washing and using of face mask by the mothers could reduce the COVID-19 transmission to the neonates. 14 Based on hospital experience, less than 50% of the participants were asked about the clinical features of COVID -19 during admission and one fifth of the participants had their body temperatures recorded by digital thermometer. Among the health workers who were involved in the delivery and clinical examination, only about 30% used Personal Protective Equipment (PPE). A study conducted by Pandey et al. identified the necessity of educating health care workers on proper and rational use of PPE while examining the patients.15
Table 4 .
4Distribution of Experience related characteristics regarding COVID-19Experience domain
Frequency Percentage
1. Ask clinical features COVID-19 during
admission
Yes
83
40.9
No
120
59.1
2. Record Body temperature
Yes
44
21.7
No
159
78.3
3. If yes, which type
Digital Thermometer
44
21.7
Mercury thermometer
0
0.0
Infrared thermometer
0
0.0
4. Do health workers wear PPE while
examination in ward?
Yes
56
27.6
No
147
72.4
5. Do health workers wear PPE while
conducting delivery?
Yes
61
30.0
No
142
70.0
ACKNOWLEDGEMENTThe authors have not received any financial support for research. The authors would also like to thank Dr. SantoshTimilsina for assistance and also all the postpartum mothers who participated in the study.
Epidemiological and clinical features of 2019 novel coronavirus diseases (COVID-19) in the South of Iran. R Shahriarirad, Z Khodamoradi, A Erfani, H Hosseinpour, K Ranjbar, Y Emami, Shahriarirad R, Khodamoradi Z, Erfani A, Hosseinpour H, Ranjbar K, Emami Y, et al. Epidemiological and clinical features of 2019 novel coronavirus diseases (COVID-19) in the South of Iran.
Attitude and Practice towards COVID-19 among Chronic Disease Patients at Addis Zemen Hospital, Northwest Ethiopia. Y Akalu, B Ayelign, M D Molla, Knowledge, 10.2147/IDR.S258736Infect Drug Resist. 13Akalu Y, Ayelign B, Molla MD. Knowledge, Attitude and Practice towards COVID-19 among Chronic Disease Patients at Addis Zemen Hospital, Northwest Ethiopia. Infect Drug Resist. 2020;13:1949-1960. https://doi.org/10.2147/IDR.S258736
Analysis of the susceptibility to COVID-19 in pregnancy and recommendations on potential drug screening. X Zhao, Y Jiang, Y Zhao, H Xi, C Liu2, F Qu, X Feng, 10.1007/s10096-020-03897-6European Journal of Clinical Microbiology and Infectious Diseases. 392Zhao X, Jiang Y, Zhao Y, Xi H, Liu2 C, Qu F, Feng X. Analysis of the susceptibility to COVID-19 in pregnancy and recommendations on potential drug screening. European Journal of Clinical Microbiology and Infectious Diseases. 2020;39:1209-20. Received: 11 March 2020 / Accepted: 2 April 2020, https://doi.org/10.1007/s10096-020-03897- 6
Coronavirus disease 2019: Knowledge, attitude, and practice of pregnant women in a tertiary hospital. C C Anikwe, C O Ogah, I H Anikwe, B C Okorochukwu, C C Ikeoha, Abakaliki, southeast NigeriaAnikwe CC, Ogah CO, Anikwe IH, Okorochukwu BC, Ikeoha CC. Coronavirus disease 2019: Knowledge, attitude, and practice of pregnant women in a tertiary hospital in Abakaliki, southeast Nigeria.
. 10.1002/ijgo.13293Int J Gynecol Obstet. Int J Gynecol Obstet. 2020; 1-6, http://www.wileyonlinelibrary.com/ journal/ijgo. https://doi.org/10.1002/ijgo.13293
Maternal Anxiety During Pregnancy and the Association With Adverse Perinatal Outcomes: Systematic Review and Meta-Analysis. S Grigoriadis, L Graves, M Peer, J Clin Psychiatry. 79Grigoriadis S, Graves L, Peer M, et al. Maternal Anxiety During Pregnancy and the Association With Adverse Perinatal Outcomes: Systematic Review and Meta-Analysis. J Clin Psychiatry. 2018;79:17r120
Outbreak of Coronavirus Disease (COVID-19). N K Chaudhary, Journal of Chitwan Medical College. 1031Available online at: www.jcmc.cmc.edu.npChaudhary NK. Outbreak of Coronavirus Disease (COVID-19). Journal of Chitwan Medical College. 2020;10 (31):1-2 Available online at: www.jcmc.cmc.edu.np
Knowledge of Health Care professionals and Medical Students Regarding COVID-19 in a Tertiary Care Hospital in Nepal. H C Neupane, N Shrestha, S Adhikari, S Angadi, B K Shrestha, B Gauli, Doi:10.31729/jnma.4995J Nepal Med Assoc. 58227Neupane HC, Shrestha N, Adhikari S, Angadi S, Shrestha BK, Gauli B. Knowledge of Health Care professionals and Medical Students Regarding COVID-19 in a Tertiary Care Hospital in Nepal. J Nepal Med Assoc. 2020;58(227):480-6.Doi:10.31729/jnma.4995
Maternal and perinatal outcomes with COVID-19: A systematic review of 108 pregnancies. M Zaigham, O Andersson, 10.1111/aogs.13867Acta Obstet Gynecol Scand. 99Zaigham M, Andersson O. Maternal and perinatal outcomes with COVID-19: A systematic review of 108 pregnancies. Acta Obstet Gynecol Scand. 2020;99:823-9. DOI: 10.1111/aogs.13867
Providing maternal health services during the COVID-19 pandemic in Nepal. The Lancet Global Health. R Karkee, A Morgan, Karkee R, Morgan A. Providing maternal health services during the COVID-19 pandemic in Nepal. The Lancet Global Health. 2020 Aug 10.
Effect of the COVID-19 pandemic response on intrapartum care, stillbirth, and neonatal mortality outcomes in Nepal: a prospective observational studyy. Kc A, R Gurung, V M Kinney, 10.1016/S2214-109X(20)30345-4.publishedonlineAug10Lancet Glob Health. KC A, Gurung R, Kinney VM. Effect of the COVID-19 pandemic response on intrapartum care, stillbirth, and neonatal mortality outcomes in Nepal: a prospective observational studyy. Lancet Glob Health. 2020 doi: 10.1016/S2214-109X(20)30345-4. published online Aug 10
More effective strategies are required to strengthen public awareness of COVID-19: Evidence from Google Trends. D Hu, X Lou, Z Xu, N Meng, Q Xie, M Zhang, Journal of Global Health. 101Hu D, Lou X, Xu Z, Meng N, Xie Q, Zhang M, et al. More effective strategies are required to strengthen public awareness of COVID-19: Evidence from Google Trends. Journal of Global Health. 2020 Jun;10(1).
COVID-19: should the public wear face masks?. B Javid, M P Matheson, N J , BMJ. 2020Javid B, weekes MP, Matheson NJ. COVID-19: should the public wear face masks? BMJ. 2020:369 doi: https://doi.org/100.1136/bmj. m1442(published 09 April 2020),
COVID-19): Infection control and prevention measures. V Jorden, Corona, Virus, 10.1072/HC15950Journal of Primary Healthcare. 121Jorden V. Corona Virus (COVID-19): Infection control and prevention measures. Journal of Primary Healthcare. 2020;12(1):296-97. DOI: https://doi.org/10.1072/HC15950.
Breastfeeding and coronavirus disease-2019: Ad interim indications of the Italian Society of Neonatology endorsed by the Union of European Neonatal & Perinatal Societies. Maternal & Child Nutrition. R Davanzo, G Moro, F Sandri, M Agosti, C Moretti, F Mosca, Davanzo R, Moro G, Sandri F, Agosti M, Moretti C, Mosca F. Breastfeeding and coronavirus disease-2019: Ad interim indications of the Italian Society of Neonatology endorsed by the Union of European Neonatal & Perinatal Societies. Maternal & Child Nutrition. 2020 Apr 3:e13010.
Perception of understanding COVID-19 among doctors at Patan Hospital, Nepal. B Pandey, M Lama, P K Shah, P Rajbhandari, K Sigdel, N Hirachan, 10.3126/jpahs.v7i1.28855Journal of Patan Academy of Health Sciences. 71Pandey B, Lama M, Shah PK, Rajbhandari P, Sigdel K, Hirachan N. Perception of understanding COVID-19 among doctors at Patan Hospital, Nepal. Journal of Patan Academy of Health Sciences. 2020Apr; 7(1):13-18. DOI: https://doi.org/10.3126/jpahs. v7i1.28855.
What are the risks of COVID-19 infection in pregnant women?. J Qiao, Doi:10.1016/S0140-6736(20Lancet. 395Qiao J. What are the risks of COVID-19 infection in pregnant women? Lancet. 2020; 395(10226):760-762. Doi: 10.1016/S0140- 6736(20)30365-2
Antenatal and postnatal mental health: clinical management and service guidance. National Institute for Health and Care ExcellenceClinical guideline 192National Institute for Health and Care Excellence. Antenatal and postnatal mental health: clinical management and service guidance. Clinical guideline 192. 2020. https://www.nice.org.uk/guidance/ cg192. Accessed June 21, 2020
| [
0.09050397574901581,
0.07662223279476166,
-0.06684216111898422,
0.09638214111328125,
0.05940259248018265,
0.051189132034778595,
-0.010499085299670696,
0.25019052624702454,
0.02954649180173874,
0.07873450964689255,
0.10463052988052368,
-0.06913188099861145,
0.0624283105134964,
0.01656369492... |
Spatial interaction between weather and socio-demographic factor as influencing variables for COVID-19 spread in Iraq
2023
Azad Rasul
· Sa'ad Ibrahim
Spatial interaction between weather and socio-demographic factor as influencing variables for COVID-19 spread in Iraq
Inf. Res
31202310.1007/s41324-022-00497-8Received: 17 August 2022 / Revised: 3 November 2022 / Accepted: 3 November 2022 / Published online: 14 November 2022
Introduction
SARS-CoV2 is increasingly recognised as an important, worldwide public health concern. The number of confirmed cases and casualties of SARS-CoV2, on a global scale, has significantly increased. These have drawn the attention of researchers and policy-makers to devise measures against the rapid development of diseases by providing guidance and options for a better healthcare delivery needed to address the prevailing and future challenges [1]. It has been postulated that the peak time of the transmission of these diseases is most peculiar to a specific season and weather conditions, for instance, the peak of SARS-CoV1 occurred during the spring while MERS-CoV was transmitted in the warm climate during spring and summer seasons [2]. In contrast, the transmission of influenza shows seasonality in the regions with a temperate climate where the peak of infections happens during winter [3][4][5].
The spread of COVID-19 could be influenced by weather and climatic variables and human demographic variables such as population density, culture, and country measures against the disease [2]. On the global scale, association between per country COVID-19 cases and principal climatic variables were examined by previous studies [5]. The research reported a significant weak inverse relationship between R 0 of COVID-19 cases and wind speed. At the local scale, some research were carried out to evaluate the association between COVID-19 disease and climatic variables. For instance, in Iran, a study reported that COVID-19
Abstract Weather and sociodemographic indicators are important to comprehensively understand rapid spread of COVID-19 at a given spatial scale and spatial analysis is very useful in studying the causes of disease. This study evaluates the influence of weather variables, sociodemographic characteristics and their corresponding records of COVID-19 in Iraq governorates. The assessments of these relationships were based on R 0 estimated from the time series data of COVID-19 infections, and by using geographically weighted regression (GWR) and linear regression modelling. The results showed that global estimates of these relationships from the linear regressions are generally poor. On the contrary, GWR results show spatially varying patterns. Among weather variables, increasing wind speed leads to rising COVID-19 infection. Population density is one of the sociodemographic characteristics that contribute to higher COVID-19 infection. COVID-19 infections, on the other hand, decreased in cities with a good health index and access to piped water. The findings of this study are therefore of great value to policymakers to design appropriate measures to reduce COVID-19 infection. This demonstrates the importance of spatial information methods in quantifying the impact of different variables on disease spread.
3
infection is high in cities with low degrees of wind speed, humidity, and solar radiation [6]. In China, linear regression was used to assess the impact of temperature in the cities. Results indicated that high temperatures and high humidity significantly reduced the spread of COVID-19 in 100 cities [7]. A tropical case study, in Rio de Janeiro, Brazil, concludes that the spread of COVID-19 could be suppressed by high solar radiation [8]. In Jakarta, Indonesia, results display COVID-19 pandemic is weakly positively correlated with average temperature [9].
To date, only weak evidence is provided by peer reviewed published papers confirming that SARS-CoV-2 is more transferrable under lower air temperatures and low absolute humidity. In addition, the reported relationships between SARS-CoV-2 and air pollution, UV, and wind speed are ambiguous. There is, therefore, the need for researchers to critically investigate the influence of environment and weather on the virus and the disease. This means that the impact of weather and climate variables on COVID-19 infection is not only localized but also at experimental stages.
One other question is whether socio-economic and sociodemographic variables of the people may affect the transmission of COVID-19 infection. The influence of these variables on the spread of COVID-19 infection is still not well understood. Examples of these variables are population size, population density, the degree of urbanization and poverty [10]. Despite the fact that different results were reported in the literature about the influence of environmental conditions on the COVID-19, it is still quite imperative to study the influence of the daily weather and sociodemographic elements on the virus in Iraq (at the local scale). In addition, having more observations and dense time series data regarding the new Coronavirus can reveal a pattern that may not have been explored in the past, perhaps by using strict hypotheses and the development of analytical methods and statistical models [10]. The use of GWR for evaluating the relationships between environmental and human factors and COVID-19 has been not been adequately researched.
In this study, we aimed to investigate whether COVID-19 detection is related to weather elements and sociodemographic indicators in Iraqi cities, which is important to comprehensively understand the factors that contribute to rapid spread of the disease at a given spatial scale. Specifically, we evaluated the relationship between weather and climate elements and sociodemographic variables and COVID-19 using GWR and Multiple Linear Regression (MLR). A recent study by Wu and Zhang [11], who explore the spatial-temporal varying impacts on cumulative case in Texas using GWR, emphasized that there is a lack of country level research on COVID-19 GWR modeling. The findings should make an important contribution to policymakers to enable them to prepare measures and strategize against this disease. A novel contribution of the research is the use of GWR methods to examine the role of climate and social factors in the spread and variation of COVID-19 in Iraqi governorates.
Materials and methods
Data
Data of daily the affected people with COVID-19 in each Iraqi governorate were collected from daily announcements of Iraqi Ministry of Health [12]. The data collected started from 24th of February, which is the first day of COVID-19 detection in Iraq to 31st of December 2021. Daily data of weather elements (air temperature, relative humidity, dewpoint, atmospheric pressure, visibility and wind speed) across weather stations in the country were obtained using "worldmet" package of R programming [13]. Surface meteorological data of Iraqi weather stations were downloaded by the package from NOAA Integrated Surface Database (ISD). The sociodemographic data such as health index, density, urbanization and mean years of schooling were downloaded from Global Data Lab, Institute for Management Research, Radboud University [14]. For Covid-19 and socioeconomic variables all 18 governorates of Iraq used in the research, but for climatic variables because of having a huge gap in the climatic data we used 16 Iraqi governorates.
Statistical analysis
In the R 0 estimations, to make an accurate rate of transmission, only those data after 30 cases of COVID-19 were reported in each governorate was used [10]. The basic R 0 transmissibility projection based on Cori's et al. [15] framework was adopted in this study (Eq. 1). This method generates robust analytical speculates of R. If the result of R 0 is higher than 1, it means the virus is spreading rapidly [16]. This estimate of R t from time series of cases provides the R 0 of the endemic [15].
Association between R 0 of the daily confirmed cases of COVID-19 of Iraqi governorates and daily weather variables were assessed. We converted the hourly data of downloaded weather stations to daily data before data analyses. Geographically weighted regression (GWR) and Multiple Linear Regression (MLR) methods were applied to quantify the linear and spatial relationships. We examined climatic variables and the new number of Covid-19 infections during the same day for Iraqi governorates. Because maybe the climatic variables do not affect the infection of the virus during the same day we examined this association between the climatic variables and the number of Covid-19 infections after 3 days (lag3), after 7 days (lag7) and after the 14 days (lag14).
Statistical analyses were executed in R programming (e.i. spgwr [17] and sp [18] packages). In this study GWR, multivariate regression was performed and preferred over univariate regression. GWR is localized regression suggested by Brunsdon et al. [19] which assesses non-stationary variables [20]. The model is stated as (Eq. 2) and MLR is expressed as (Eq. 3).
where E I t is the mathematical expectation of the random variablI t .
where u i ,v i implies the coordinates of the i th point in space, 0 and k are parameters to be estimated, and i is the random error term at point i.
where y dependent variable, b 0 y-intercept, x explanatory variables, b n slop for x n . (1) R t = E � I t � ∑ t s=1 I t−s w s (2) y i = 0 u i ,v i + ∑ k k (u i ,v i )x ik + i (3) y = b 0 + b 1 x 1 + b 2 x 2 + ⋯ + b n x n
Results
Relationship between daily climatic variables and R 0 of COVID-19 in Iraq
The relationship between daily data of climatic factors and lag7 of the R 0 index of COVID-19 cases in Iraq is depicted in Table 1; Fig. 1. Table 1 indicated that at the global scale, the highest positive regression coefficients with wind speed was on the same day, lag7 and lag14 (0.04) while the highest relationship with air temperature was found on the same day (0.02). With regards to air pressure, the highest coefficient (0.03) was on the same day. Based on GWR at local coefficients, the strongest relationship of wind speed and temperature was on the same day. In general, lag7 performed better than the same day, lag3 and lag14; therefore, we choose lag7 in this research for further analysis. Based on MLR method and global regression, air pressure (p = 0.034) and wind speed (p = 0.088) have significant relationship with lag7 of R 0 COVID-19 infection ( Table 2). In particular, air temperature and wind speed had a positive relationship with COVID-19 infection and increasing temperature, air pressure and wind speed could potentially increase COVID-19 infection by 0.025, 0.026 and 0.045, respectively, per unit. In contrast, visibility was found to have a negative relationship with COVID-19 infection ( Table 2). At local coefficients, the GWR method showed a positive coefficient COVID-19 infection with wind speed (0.02-0.051), temperature (0-0.02), visibility (0-0.01) and relative humidity (rh) in all Iraqi Governorates (Fig. 1). Regarding air pressure and dew point, the relationship varies, as there are positive as well as negative relationships in different cities.
Relationship between the sociodemographic variables and COVID-19 infection of Iraq
After assessing the relationship between weather variables and R0 of COVID-19 infection in the last section, we selected a list of sociodemographic variables to analyses how they are associated with a cumulative number of COVID-19 infections in Iraqi Governorates. On a global scale, as Table 3 indicated, COVID-19 infection has a positive relationship with seven of the variables assessed, such as density (P-value < 0.01), human development index and the number population of the governorates. In contrast, negative relationships were observed with four of the sociodemographic variables such as standard of living index, education index, and having piped water. This means the risk of COVID-19 infection reduces in cities with high education index and availability of piped water, compared to cities with a low education index and less availability of piped water. However, based on LMS method the association between sociodemographic variables and COVID-19 infection was only statistically significant with population density (P < 0.01).
GWR method shows that the relationship between sociodemographic variables and the number of COVID-19 infections does not strongly vary spatially. Number of population is the only variable that shows a striking difference in terms of the relationship with COVID-19 infection. A negative relationship was found in southern parts of the country. However, a positive GWR coefficient was found in northern Iraq (Table 4; Fig. 2). Regression coefficients of the urbanization, human development index and population density are positive and do not vary significantly around the cities for the entire country.
Discussion
In this study, the correlation between weather and climatic variables (e.g. air temperature, relative humidity, dew point, atmospheric pressure, visibility and wind speed), sociodemographic variables (e.g. human development index, health index, standard of living index, population numbers, urbanization, education index, density etc.) and their corresponding records of the COVID-19 infection were analysed in Iraq. Weather factors and sociodemographic variables can trigger the spread of Coronavirus infection [6,9,21].
In general, this research shows that the lag7 of COV-ID-19's R 0 performed better than the same day, lag3 and lag14. Based on global regression, wind speed significantly (P = 0.088) and positively correlated with R0 COVID-19 infection. It is also significantly correlated with air pressure (P = 0.034), however, covid-19 infection is not sensitive to air temperature in Iraqi cities because the peak of covid-19 infection occurred during the summer and winter and the regression with temperature is not statistically significant. Local coefficients of COVID-19 infection with wind speed and air temperature based on GWR method show a positive coefficient in all sixteen assessed governorates of Iraq.
A study by Tosepu et al. (2020) who studied the correlation between weather and COVID-19 pandemic in Jakarta, Indonesia found that only average temperature significantly correlated with COVID-19 pandemic (r = 0.392, P < 0.01). Another study by Bashir et al. (2020) found that both average temperature, minimum temperature and air quality have a significant correlation with COVID-19 epidemic in New York, United State of America (USA). These findings are supporting the view that presently there is no scientific evidence yet that warm weather would reduce COVID-19 epidemic [21,22].
Furthermore, the relationships between the 11 potential sociodemographic characteristics of the referenced population and their corresponding records of COVID-19 infection were investigated. The results indicated that (based on MLR method) the relationships between sociodemographic variables and COVID-19 infection were statistically significant and strongly positive with population density (P < 0.01). Based on GWR this positive association does not vary around the cities in Iraq (Table 3; Fig. 2).
Our result on the relationship between population density and Coronavirus infection is similar to the findings of Rashed et al. (2020) who studied the influence of absolute humidity, temperature and population density on COVID-19 spread and decay durations in Japan, discovered that population density was shown to be a major factor, affecting the spread and decay patterns [23]. Similarly, a study on COVID-19 pandemic which calculates the relative risk of the importation and exportation of the COVID-19 virus from every airport in local municipalities around the world, based on global spatial and mapping information demonstrates that a larger reduction in air travel (in high risk areas) through airports would lead to a gradual decrease in the risk flow. They further emphasized that airport management or government with airports in their jurisdiction should employ stringent countermeasures [24].
One of the most important contributions of this study is that it offers some important insights into the influence of varied environmental factors, climatic extremity and sociodemographic factors for assessing their influence on COVID-19 infection in Iraq. This is a holistic approach and therefore remarkable at the time policymakers are looking for options to design mitigation policies to contain and prevent this disease. The influence of seasonality on COVID-19 is still uncertain. Some studies have so far postulated that there is a likelihood for a seasonality-sensitive subsequent waves of infections about one year after the initial outbreak [22]. This means that due attention requests to be on policy design in order to flatten the curve. Specifically, there is a requirement to design policies on the most important sociodemographic factors as revealed by this study, such as those on travel restrictions and social distancing.
Conclusion
This study set out to evaluate the influence of weather and climate, and sociodemographic variables on COVID-19 infection in Iraq, using the GWR and MLR method.
The main findings were that among weather variables increasing wind speed leads to risen COVID-19 infection however covid-19 infection is not sensitive to air temperature in Iraqi cities because the peak of covid-19 infection occurred during the summer and winter. Among sociodemographic variables, population density leads to more high COVID-19 infection than others (P < 0.01). In contrast, COVID-19 infections declined in cities with high health index and access to piped water. This study recommends to policymakers the need for due attention, proper control and prevention, specifically, there is a need to design or strengthen policies on the most important sociodemographic factors as revealed in this study, such as social distancing. We acknowledged the limitation of our study due to uncertainties arising from the data, for example given the delays in the development of symptoms and testing of the infected persons, which may lead to under-accounting of the confirmed cases.
Development Index, (b) Health Index, (c) Standard of Living Index, (d) Education Index, (e) Life expectancy, (f) Gross National Income per Capita, (g) % Piped water, (h) % Pop 65+, (i) Population in millions, (j) Urbanization, (k) Density Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.
Table 1
1Summary statistics of GWR coefficient parameter estimates between daily climatic variables and R 0 of COVID-19 in IraqIntercept.
Wind speed
Average
temperature
Visibility
Dewpoint
Air pressure
Relative humidity
Sameday
Min.
− 41.198
0.045
0.025
− 0.000022
− 0.046
0.019
− 0.006
Median
− 23.595
0.052
0.036
− 0.000008
− 0.011
0.024
0.003
Max
− 19.959
0.058
0.054
− 0.000002
0.024
0.041
0.015
P-value
0
0
0
0
0
0
0
Global
− 26.03
0.04
0.02
0.00
0.01
0.03
0.00
lag3
Min.
− 9.428
0.008
-0.008
0.000038
− 0.058
− 0.022
− 0.009
Median
7.068
0.024
0.008
0.000045
− 0.023
− 0.006
0.002
Max.
22.505
0.052
0.021
0.000075
0.025
0.010
0.013
P-value
0.00
0.00
0.31
0.00
0.00
0.00
0.00
Global
3.09
0.03
0.00
0.00
− 0.01
0.00
0.00
lag7
Min.
− 3.874
0.035
0.009
0.000039
− 0.013
− 0.002
0.001
Median
− 0.306
0.046
0.011
0.000041
− 0.007
0.001
0.004
Max.
2.110
0.051
0.013
0.000042
0.004
0.004
0.006
P-value
0
0
0
0
0
0
0
Global
− 0.60
0.04
0.01
0.00
0.00
0.00
0.00
lag14
Min.
6.961
0.025
0.012
0.000003
− 0.071
− 0.017
0.001
Median
11.316
0.033
0.019
0.000013
− 0.031
− 0.011
0.007
Max.
16.103
0.064
0.049
0.000033
− 0.0003
− 0.006
0.022
P-value
0
0
0
0
0
0
0
Global
10.22
0.04
0.01
0.00
− 0.01
− 0.01
0.00
Table 2
2Statistics of regression between climatic variables and sameday R 0 of COVID-19 in Iraq based on the Multiple Linear Regression methodSignif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Estimate
Std. error
t value
Pr (>|t|)
Intercept
− 26.031
12.894
− 2.02
0.044*
ws
0.045
0.026
1.71
0.088.
Temp
0.025
0.022
1.14
0.255
Viss
− 0.00001
0.00005
− 0.27
0.784
Dew
0.005
0.022
0.23
0.816
Pre
0.026
0.012
2.12
0.034*
rh
− 0.002
0.009
− 0.27
0.790
Table
1 ' ' 1Table 4 Parameter coefficients of the multivariate regression model between sociodemographic variables and COVID-19 infection of Iraq based on the GWR methodEstimate
Std. error
t value
Pr (>|t|)
(Intercept)
3,759,100
6,276,087
0.60
0.5711
a
3,338,636
4,174,408
0.80
0.4543
b
1,920,829
20,088,989
0.10
0.9269
c
− 4,631,187
8,716,676
− 0.53
0.6143
d
− 1,812,658
1,738,884
− 1.04
0.3374
e
− 53,453
269,636
− 0.20
0.8494
f
51
84
0.60
0.5683
g
− 1021
877
− 0.16
0.2888
h
17,382
22,205
0.78
0.4635
i
24,981
14,402
1.73
0.1335
j
443
1040
0.43
0.6848
k
262
46
5.71
0.0012**
(a) Human Development Index, (b) Health Index, (c) Standard of
Living Index, (d) Education Index, (e) Life expectancy, (f) Gross
National Income per Capita, (g) % Piped water, (h) % Pop 65+, (i)
Population in millions, (j) Urbanization, (k) Density
Min.
Median
Max.
P-value
Intercept 3,427,005
7,823,990
10,737,878
0.15
a
2,375,934
2,777,869
3,583,718
0.21
b
− 16,469,861 − 7,300,561
10,869,594
0.15
c
− 16,929,701 − 12,069,990 − 6,162,221 0.45
d
− 2,022,902
− 1,711,804
− 1,383,502 0.18
e
− 181,393
69,897
197,090
0.15
f
61
118
168
0.39
g
− 749
96
567
0.56
h
6804
24,594
29,014
0.37
i
19,147
37,745
54,163
0.14
j
6
124
1075
0.22
k
193
226
290
0.15
Author contributionsAR, SI: Conceptualization; AR, SI; Data curation, Formal analysis; Methodology; AR, SI; Visualization; AR; Writing -original draft, review & editing SI, AR.Funding This research received no external funding.
Validity and usefulness of COVID-19 models. S Eker, 10.1057/s41599-020-00553-4s41599-020-00553-4Humanities and Social Sciences Communications. 71Eker, S. (2020). Validity and usefulness of COVID-19 mod- els. Humanities and Social Sciences Communications, 7(1), 1-5. https:// doi. org/ 10. 1057/ s41599-020-00553-4
Climate effect on COVID-19 spread rate: An online surveillance tool. G Caspi, U Shalit, S L Kristensen, D Aronson, L Caspi, O Rossenberg, A Shina, O Caspi, 10.1101/2020.03.26.20044727727Caspi, G., Shalit, U., Kristensen, S. L., Aronson, D., Caspi, L., Rossenberg, O., Shina, A., & Caspi, O. (2020). Climate effect on COVID-19 spread rate: An online surveillance tool. MedRxiv. https:// doi. org/ 10. 1101/ 2020. 03. 26. 20044 727
Will coronavirus pandemic diminish by summer? Available at SSRN 3556998. Q Bukhari, Y Jameel, 10.2139/ssrn.3556998Bukhari, Q., & Jameel, Y. (2020). Will coronavirus pandemic diminish by summer? Available at SSRN 3556998. https:// doi. org/ 10. 2139/ ssrn. 35569 98
Temperature, humidity, and latitude analysis to predict potential spread and seasonality for COVID-19. M M Sajadi, P Habibzadeh, A Vintzileos, S Shokouhi, F Miralles-Wilhelm, A Amoroso, 10.2139/ssrn.3550308Social Science Research Network. Sajadi, M. M., Habibzadeh, P., Vintzileos, A., Shokouhi, S., Miralles-Wilhelm, F., & Amoroso, A. (2020). Temperature, humidity, and latitude analysis to predict potential spread and seasonality for COVID-19. Social Science Research Net- work. https:// doi. org/ 10. 2139/ ssrn. 35503 08
The role of climate in the spread of COVID-19 in different latitudes across the world. A Rasul, H Balzter, 10.3390/covid2090085COVIDRasul, A., & Balzter, H. (2022). The role of climate in the spread of COVID-19 in different latitudes across the world. COVID, 2(9), 1183-1192. https:// doi. org/ 10. 3390/ covid 20900 85
Investigation of effective climatology parameters on COVID-19 outbreak in Iran. M Ahmadi, A Sharifi, S Dorosti, S J Ghoushchi, N Ghanbari, 10.1016/j.scitotenv.2020.138705Science of the Total Environment. 138705Ahmadi, M., Sharifi, A., Dorosti, S., Ghoushchi, S. J., & Ghan- bari, N. (2020). Investigation of effective climatology parameters on COVID-19 outbreak in Iran (p. 138705). Science of the Total Environment. https:// doi. org/ 10. 1016/j. scito tenv. 2020. 138705
High temperature and high humidity reduce the transmission of COVID-19. J Wang, K Tang, K Feng, W Lv, Available at SSRN 3551767Wang, J., Tang, K., Feng, K., & Lv, W. (2020). High temperature and high humidity reduce the transmission of COVID-19. Avail- able at SSRN 3551767.
Relationship between COVID-19 and weather: Case study in a tropical country. D K Rosario, Y S Mutz, P C Bernardes, C A Conte-Junior, 10.1016/j.ijheh.2020.113587International Journal of Hygiene and Environmental Health. 229Rosario, D. K., Mutz, Y. S., Bernardes, P. C., & Conte-Junior, C. A. (2020). Relationship between COVID-19 and weather: Case study in a tropical country. International Journal of Hygiene and Environmental Health, 229, 113587. https:// doi. org/ 10. 1016/j. ijheh. 2020. 113587
R Tosepu, J Gunawan, D S Effendy, H Lestari, H Bahar, P Asfian, Correlation between weather and Covid-19 pandemic in Jakarta Indonesia. 138456Tosepu, R., Gunawan, J., Effendy, D. S., Lestari, H., Bahar, H., & Asfian, P. (2020). Correlation between weather and Covid-19 pandemic in Jakarta Indonesia (p. 138456). Science of the Total Environment.
Winter is coming: A southern hemisphere perspective of the environmental drivers of SARS-CoV-2 and the potential seasonality of COVID-19. A J Smit, J M Fitchett, F A Engelbrecht, R J Scholes, G Dzhivhuho, N A Sweijd, International Journal of Environmental Research and Public Health. 17165634Smit, A. J., Fitchett, J. M., Engelbrecht, F. A., Scholes, R. J., Dzhivhuho, G., & Sweijd, N. A. (2020). Winter is coming: A southern hemisphere perspective of the environmental drivers of SARS-CoV-2 and the potential seasonality of COVID-19. Inter- national Journal of Environmental Research and Public Health, 17(16), 5634.
Exploration of spatial-temporal varying impacts on COVID-19 cumulative case in Texas using geographically weighted regression (GWR) (pp. 1-15). Environmental Science and Pollution Research. X Wu, J Zhang, 10.1007/s11356-021-13653-8Wu, X., & Zhang, J. (2021). Exploration of spatial-temporal varying impacts on COVID-19 cumulative case in Texas using geographically weighted regression (GWR) (pp. 1-15). Environ- mental Science and Pollution Research. https:// doi. org/ 10. 1007/ s11356-021-13653-8
The daily epidemiological situation of the new Corona pandemic in Iraq. moh.gov.iqmoh.gov.iq (2022). The daily epidemiological situation of the new Corona pandemic in Iraq. https://Moh.Gov.Iq/. https:// moh. gov. iq/
Worldmet: Import surface meteorological data from NOAA integrated surface database (ISD). D Carslaw, R packageCarslaw, D. (2021). Worldmet: Import surface meteorological data from NOAA integrated surface database (ISD). R package.
Global data lab-innovative instruments for turning data into knowledge. Gdl, GDL (2022). Global data lab-innovative instruments for turning data into knowledge. https://globaldatalab.org/.
A new framework and software to estimate time-varying reproduction numbers during epidemics. A Cori, N M Ferguson, C Fraser, S Cauchemez, American Journal of Epidemiology. 1789Cori, A., Ferguson, N. M., Fraser, C., & Cauchemez, S. (2013). A new framework and software to estimate time-varying reproduc- tion numbers during epidemics. American Journal of Epidemiol- ogy, 178(9), 1505-1512.
Ebola virus disease in West Africa-the first 9 months of the epidemic and forward projections. W E R Team, New England Journal of Medicine. 37116Team, W. E. R. (2014). Ebola virus disease in West Africa-the first 9 months of the epidemic and forward projections. New Eng- land Journal of Medicine, 371(16), 1481-1495.
Package 'spgwr. R Bivand, D Yu, T Nakaya, M A Garcia-Lopez, Bivand, R., Yu, D., Nakaya, T., & Garcia-Lopez, M. A. (2022). Package 'spgwr'. 2015.
E Pebesma, R Bivand, B Rowlingson, V Gomez-Rubio, R Hijmans, M Sumner, D Macqueen, J Lemon, F Lindgren, J O'brien, J Rourke, sp: Classes and Methods for Spatial Data (1.5-0). Pebesma, E., Bivand, R., Rowlingson, B., Gomez-Rubio, V., Hij- mans, R., Sumner, M., MacQueen, D., Lemon, J., Lindgren, F., O'Brien, J., & O'Rourke, J. (2022). sp: Classes and Methods for Spatial Data (1.5-0). https:// CRAN.R-proje ct. org/ packa ge= sp.
Geographically weighted regression: A method for exploring spatial nonstationarity. C Brunsdon, A S Fotheringham, M E Charlton, Geographical Analysis. 284Brunsdon, C., Fotheringham, A. S., & Charlton, M. E. (1996). Geographically weighted regression: A method for exploring spa- tial nonstationarity. Geographical Analysis, 28(4), 281-298.
Dynamics of land surface temperature in response to land-use/cover change. X Zhou, Y C Wang, Geographical Research. 491Zhou, X., & WANG, Y. C. (2011). Dynamics of land surface temperature in response to land-use/cover change. Geographical Research, 49(1), 23-36.
Correlation between climate indicators and COVID-19 pandemic. M F Bashir, B Ma, B Komal, M A Bashir, D Tan, M Bashir, 10.1016/j.scitotenv.2020.138835Science of The Total Environment. 138835Bashir, M. F., Ma, B., Komal, B., Bashir, M. A., Tan, D., & Bashir, M. (2020). Correlation between climate indicators and COVID-19 pandemic in New York, USA (p. 138835). Science of The Total Environment. https:// doi. org/ 10. 1016/j. scito tenv. 2020. 138835
Test for Covid-19 seasonality and the risk of second waves. F A Engelbrecht, R J Scholes, 10.1016/j.onehlt.2020.100202Engelbrecht, F. A., & Scholes, R. J. (2020). Test for Covid-19 sea- sonality and the risk of second waves. https:// doi. org/ 10. 1016/j. onehlt. 2020. 100202
Influence of absolute humidity, temperature and population density on COVID-19 spread and decay durations: Multi-prefecture study in Japan. E A Rashed, S Kodera, J Gomez-Tames, A Hirata, International Journal of Environmental Research and Public Health. 17155354Rashed, E. A., Kodera, S., Gomez-Tames, J., & Hirata, A. (2020). Influence of absolute humidity, temperature and population den- sity on COVID-19 spread and decay durations: Multi-prefecture study in Japan. International Journal of Environmental Research and Public Health, 17(15), 5354.
Airport risk of importation and exportation of the COVID-19 pandemic. H Nakamura, S Managi, Transport Policy. 96Nakamura, H., & Managi, S. (2020). Airport risk of importation and exportation of the COVID-19 pandemic. Transport Policy, 96, 40-47.
| [
0.12391220033168793,
-0.019856639206409454,
0.03998637944459915,
0.03426401689648628,
0.09692193567752838,
0.021007591858506203,
-0.03279884532094002,
0.12426522374153137,
0.03722978010773659,
0.17146646976470947,
0.07232494652271271,
-0.057982999831438065,
0.18304717540740967,
0.150396525... |
« Panel sur la critique musicale », dans le cadre du colloque international Qu'en est-il du goût musical dans le monde au xxi e siècle ?
Caroline Marcoux
Faculté de musique
Université de Montréal, salle Serge-Garant
28 février 2013
Gendron Résumé
Faculté de musique
Université de Montréal, salle Serge-Garant
28 février 2013
« Panel sur la critique musicale », dans le cadre du colloque international Qu'en est-il du goût musical dans le monde au xxi e siècle ?
6879E3A6C25ADB09883CC281F9FB447310.7202/1060125arcritique musicalegoûtlecteurs-auditeursdiscours sur la musiqueréception musicale music criticismtastereaders-listenersdiscourse about musicmusic reception
Dans le cadre du colloque Qu'en est-il du goût musical dans le monde au xxi e siècle ?présenté à la Faculté de musique de l'Université de Montréal du 28 février au 2 mars 2013, un panel a réuni les critiques musicaux Renaud Machart (France), Anne Midgette (é.-u.) et André Péloquin (Québec, Canada) autour de la question « En quoi l'exercice de la critique musicale participe-t-il à l'édification du goût musical des lecteurs-auditeurs ?».Une série d'enjeux a été abordée au cours de cet échange, dont les objectifs de la critique musicale, son influence sur les lecteurs-auditeurs, mais aussi les obligations éthiques du critique et l'avenir de cette pratique.Les points de vue des trois participants se sont révélés différents à bien des égards, à l'image de la diversité des genres musicaux dont ils traitent, de leurs parcours professionnels respectifs ainsi que des contextes géographiques au sein desquels ils oeuvrent.
La critique musicale tantôt fascine, tantôt dérange, mais toujours revêt un caractère insaisissable ; s 'agit-il d'un art, d'une science, d'un métier ? (Berthet 2006, p. 67-68).Dans le cadre du colloque sur l'esthétique musicale intitulé Qu'en est-il du goût musical dans le monde au xxi e siècle ?et présenté à la Faculté de musique de l'Université de Montréal du 28 février au 2 mars 2013, un panel a réuni trois critiques musicaux d'horizons différents.Renaud Machart (France), Anne Midgette (États-Unis) et André Péloquin (Québec, Canada) se sont intéressés à la question « En quoi l'exercice de la critique musicale participe-t-il à l'édification du goût musical des lecteurs-auditeurs ?» et ont répondu aux interrogations du public venu nombreux pour l'occasion.L'échange s'est articulé à la fois autour d'aspects pragmatiques -les genres musicaux traités, les médias à travers lesquels s'exprime le critique, les « objets » discutés (disque, concert, etc.), le public visé -et de thèmes en appelant à une vision plus personnelle des participants, notamment les objectifs de la critique musicale et son influence sur les lecteurs-auditeurs.
D'entrée de jeu, le président de séance Michel Duchesneau, musicologue dont les travaux portent notamment sur la critique musicale en France au xx e siècle, a orienté cette réflexion collective en identifiant des enjeux de la pratique ayant traversé les époques : la disparition des repères esthétiques, l'autonomie artistique de l'oeuvre, sa pertinence sociale qui supplanterait désormais les considérations esthétiques et historiques, la nature du discours sur l'oeuvre et la crainte du jugement erroné.
Le bilan de la critique musicale d'hier à aujourd'hui ainsi esquissé a lancé le débat quant à l'avenir de cette pratique.En somme, il semble que peu de réponses font consensus, à l'image de la nature souvent controversée de la critique musicale.
Présentation des ParticiPants
L'un des principaux intérêts de ce panel résidait dans la diversité des profils des trois participants.Le premier, Renaud Machart, est un critique musical notamment actif dans la presse écrite française (Le Monde, par exemple) ; il détient une formation en musique au Conservatoire de Tours et en musicologie à l'Université de Tours.À la fois directeur de festivals, animateur et producteur radio, il est l'auteur de plusieurs ouvrages, entre autres sur John Adams, Leonard Bernstein, Francis Poulenc et Stephen Sondheim.Anne Midgette, diplômée de l'Université Yale en Classical Civilization, est, quant à elle, actuellement chef critique pour la musique classique au Washington Post (é.-u.), après des débuts sur le continent européen.Au cours de sa carrière, elle a collaboré à de nombreux périodiques (The Wall Street Journal, The New York Times, Opera News, The Los Angeles Times) et coécrit les ouvrages The King and I sur Luciano Pavarotti et My Nine Lives sur le pianiste Leon Fleischer.Finalement, André Péloquin, formé en littérature comparée à l'Université de Montréal, est plutôt actif dans le
Les grands axes du PaneL
Lors du premier tour de table où chaque panéliste a exprimé sa vision de la critique musicale à l'heure actuelle, peu de recoupements ont été notés dans les témoignages étant donné la variété de genres musicaux dont traitent ces critiques et les différents moyens de diffusion qu'ils utilisent.Aux côtés du traditionnel journal se trouvent maintenant les blogues dont Péloquin et Midgette font fréquemment usage, les sites Internet spécialisés comme Pitchfork 1 , les agrégateurs de critiques tels que Metacritic, ou encore la radio, moyen de diffusion que Machart connaît en tant qu'animateur de l'émission « Le Mitan des musiciens » -nommée « Le Matin des musiciens » au moment du panel en 2013 -sur France Musique 2 et que Péloquin a fréquenté comme étudiant à l'Université de Montréal.Pour chaque média prévaut une approche différente en termes de niveau de langue, de longueur des interventions, de fréquence des publications, ce qui modifie le contact du critique avec les lecteurs-auditeurs.Par exemple, Machart affirmait que la publication dans un journal revêt un caractère impersonnel, ce qui l'a éventuellement amené à s'interroger sur les véritables destinataires de ses écrits.À l'opposé, la radio lui permet un rapide retour des auditeurs, tout comme elle offre la possibilité de diffuser les oeuvres musicales discutées.Chez Midgette, le blogue s'affirme comme un lieu d'échanges constants avec ses lecteurs, et cette notion de dialogue avec le public est apparue au coeur de ses préoccupations.À ce propos, le docteur en esthétique et sciences de l'art Dominique Berthet écrit d'ailleurs que « [l]e discours critique est en effet un jugement destiné à l'autre, qui crée une relation avec autrui » (2006, p. 106).Or, la question du rapport au lecteurauditeur se pose en de nombreux autres termes : dans le cas d'un concert, s'adresset-on à ceux qui étaient présents ou aux absents ?Vise-t-on les connaisseurs ou les néophytes ?À cet égard, il est intéressant de noter que si le critique peut être considéré comme un « auditeur particulier » (Griffiths 2004(Griffiths , p. 1063)), aucune formation ni aucun profil précis ne prédominent.Les exemples contrastants de Machart, musicien et musicologue de formation, et de Péloquin, autodidacte prônant une approche plus instinctive, illustrent cette réalité.
1
Portail américain dédié essentiellement à la musique indie.Cette plateforme se démarque par des critiques musicales au style singulier, dont la longueur et le ton se détachent souvent des normes journalistiques.Voir http://pitchfork.com(consulté le 14 octobre 2015).
2
L'activité de Machart à la radio ne relève pas précisément de la critique musicale, mais ce média n'en demeure pas moins un canal de diffusion possible pour une telle activité.
Revue musicale OICRM, volume 3, n o 1
Extrait vidéo 1 : André Péloquin et Renaud Machart à propos de leurs parcours.
Le critique musical Paul Griffiths souligne d'ailleurs que ce sont l'expérience et la perspicacité bien plus que les devoirs « faits la veille » qui déterminent la compétence dans ce domaine (2004, p. 1067).
Sur le plan des objectifs de la critique, les points de vue des panélistes ont demeuré divergents.Midgette a insisté sur le développement du sens critique de ses lecteurs, soulignant toutefois que sa démarche change lorsqu'il s'agit de musique contemporaine, où elle adopte une approche plus pédagogique visant à initier son lectorat aux compositeurs, aux oeuvres, etc. Chez Machart, il a plutôt été question de la critique comme d'un moyen de documenter, de laisser une mémoire par l'entremise d'une sorte de compte rendu.
Extrait vidéo 2 : Renaud Machart sur le rôle de mémoire joué par la critique musicale.
Plusieurs auteurs traitent d'ailleurs de cette fonction historique de la critique qui agit a posteriori, comme témoignage de la réception des oeuvres (Berthet 2006 ;Duchesneau 2007 ;Molino 2006).Finalement, Péloquin a traduit sa relation aux lecteurs par une analogie avec le métier de disquaire, qui fait des suggestions à ses clients.Selon le panéliste, cette comparaison n'est pas sans évoquer l'aspect économique omniprésent dans les médias culturels d'aujourd'hui.Bref, il apparaît que la critique peut adopter différentes formes ou « postures », pour paraphraser Duchesneau en ouverture du panel.Or, qu'en est-il maintenant de son réel impact sur le lecteur-auditeur ?
« Panel sur la critique musicale » dans le cadre du colloque international Qu'en est-il du goût musical dans le monde au xxi e siècle ?
Revue musicale OICRM, volume 3, n o 1 À ce compte, Péloquin a souligné que la critique musicale peut agir sur la vente de disques lorsque les commentaires élogieux sont repris par des publicitaires.Il considère également qu'elle aide à façonner le goût des mélomanes, opinion qu'a réfutée Midgette qui juge au contraire son pouvoir très mince et note un désintérêt marqué pour la critique à l'heure actuelle 3 .Autre son de cloche du côté de Machart qui a dit emprunter au compositeur et auteur américain Ned Rorem la phrase choc voulant que la critique ne serve qu'à « donner une opinion à ceux qui n'en ont pas ».Le panéliste français a affirmé trouver un plaisir « vaniteux » à aider à remplir les salles, mais a aussi rappelé que la critique n'est pas une science, en témoignent les opinions divergentes ayant trait à une même oeuvre.Finalement, Machart, dont le style est ouvertement incisif, a souligné que seules les très bonnes et les très mauvaises « notes » sont lues, faisant écho à Griffiths pour qui « la critique la plus efficace n'est jamais très loin de l'inconvenance » (2004, p. 1063).
Parmi les questions du public, les considérations éthiques ont été soulevées plusieurs fois et les réponses se sont faites très différentes selon le panéliste.En Europe, les invitations à des concerts et les voyages payés pour les critiques sont chose courante, tandis qu'on les interdit en Amérique.Les intervenants français et américain s'opposaient également en ce que Machart a dit écrire sur ses amis compositeurs -ce qui ne l'empêche pas d'exprimer ce qu'il pense, a-t-il précisé -tandis que Midgette y voyait une infraction à son code d'éthique.
Extrait vidéo 3 : Anne Midgette et Renaud Machart sur l'éthique du critique.
Péloquin a, quant à lui, souligné un problème inhérent au « microcosme » québécois où les gens sont peu portés sur les débats relevés.La proximité entre artistes et critiquesles premiers pouvant facilement entrer en contact avec les seconds, notamment grâce aux réseaux sociaux -induirait à son avis un climat où personne n'ose froisser un confrère.
Ainsi, la critique musicale est abordée de manière différente selon le pays, et Midgette considère d'ailleurs que le rapport économique entre un État et son milieu artistique joue un rôle à cet égard.Plus précisément, elle a expliqué que dans un pays où le financement étatique des arts est important, la critique serait une sorte de reflet de l'utilisation des fonds publics, contrairement aux États-Unis par exemple, où le milieu artistique est peu subventionné et où la critique apparaît plutôt comme un service d'orientation -de ce qui vaut la peine d'être vu et entendu.Ces considérations mettent en lumière la diversité des paramètres qui régissent la pratique de la critique musicale et ces trois témoignages révèlent une multiplicité de profils et de positions, peut-être aussi grande que la somme des individus qui s'y adonnent finalement.
Les enjeux de La critique musicaLe, d'hier à aujourd'hui Malgré la nature très libre de la discussion, le programme exposé par Duchesneau en ouverture de séance a sous-tendu l'ensemble du panel.Il s'agissait de comprendre les enjeux qui traversent l'exercice de la critique musicale, d'abord par un survol de la pratique d'hier à aujourd'hui, pour ensuite réfléchir à son avenir.
La disparition des repères esthétiques au sein d'une même culture tenait lieu de premier enjeu, et le critique Péloquin a corroboré cette idée en parlant d'un actuel « chaos du jugement » étant donné la prolifération des plates-formes qui permettent à tous d'émettre leur opinion.L'abondance et l'accessibilité de l'offre musicale décupleraient d'ailleurs le phénomène en retirant aux critiques « officiels » la primeur des oeuvres.Cette réalité a par ailleurs semblé plus marquée pour Péloquin qui travaille dans le domaine de la musique populaire et qui est très familier avec les médias électroniques.
Le deuxième enjeu était celui de l'autonomie artistique de l'oeuvre qui empêcherait le recours à des principes esthétiques partagés.Cette idée n'a pas été approfondie notamment parce que les panélistes ont évité la question des critères d'évaluation d'un jugement critique.Du peu qui a été dit sur le milieu de la création musicale, rien ne portait sur l'existence, ou plutôt l'absence de principes esthétiques communs aux oeuvres contemporaines.
Le troisième enjeu concernait la pertinence sociale de l'oeuvre qui supplanterait toute autre forme de considération, esthétique ou historique.Midgette s'est prononcée sur la question, soulignant que les gens s'identifient particulièrement à la musique qu'ils écoutent et se définissent à travers elle.La panéliste croit d'ailleurs que la difficulté observée en musique classique pour le renouvellement des publics relèverait de l'image élitiste qu'on lui attribue généralement 4 .
En ce qui concerne la nature du discours sur l'oeuvre (quatrième enjeu), Péloquin a fourni un intéressant témoignage en s'appuyant sur l'exemple du site Pitchfork.Les critiques verbeuses, qui glorifient les oeuvres autant qu'elles les détruisent, y font de la musique le prétexte d'un discours devenu le véritable centre d'intérêt.La figure de Lester Bangs, critique américain au style sans pareil et dont les écrits font l'objet de recueils (Bangs 1988(Bangs , 2003)), incarnerait, d'après le panéliste québécois, ce « culte de 4
Cette question riche a suscité l'attention de plusieurs chercheurs déjà, notamment en regard du public de jeunes adultes.Voir, entre autres, Kolb pour le contexte anglo-saxon (2000,2001) et Oliveira-Menezes pour le contexte montréalais (2015).En dernier lieu, Duchesneau avait proposé l'enjeu de la crainte du jugement erroné, qui mènerait à une conduite adogmatique.À la lumière des propos de Midgette, ce ne seraient pas tant les critiques musicaux « professionnels » que le grand public qui incarnerait ce phénomène.Elle a noté une difficulté généralisée chez les lecteurs de son blogue à émettre une opinion personnelle vis-à-vis de la musique qu'ils écoutent.Par conséquent, elle a dit encourager son lectorat à prendre la parole et à participer à un débat d'idées, adoptant une approche similaire au philosophe Marc Jimenez pour qui « le jugement de goût marque le point de départ de la réflexion esthétique ; il ne saurait être son aboutissement » (cité par ibid., p. 98-99).
Extrait vidéo 5 : Anne Midgette à propos de la participation des lecteurs sur son blogue.
En somme, la question de Duchesneau n'a pas obtenu une réponse directe de la part des panélistes.
144 Caroline MarCoux-Gendron Revue musicale OICRM, volume 3, n o 1
ProbLématiques transcuLtureLLes ?
Les deux heures réservées à ce panel auront permis de couvrir un large spectre de considérations propres à la pratique de la critique musicale ; nombre des problématiques abordées ont d'ailleurs été reprises dans d'autres conférences du colloque.Il faut par ailleurs souligner que cette séance d'ouverture avait trait à un contexte culturel et spatiotemporel très circonscrit -le contexte occidental contemporain -, tandis que le colloque se voulait un lieu de rencontres entre spécialistes qui s'interrogent sur la notion de goût musical à travers différentes sociétés.Quelques thèmes débattus par les trois critiques musicaux ont néanmoins été revisités dans des conférences portant sur d'autres traditions musicales.C'est notamment le cas de la pertinence sociale de l'oeuvre qui aurait préséance sur les considérations d'ordre esthétique.Dans un panel regroupant des ethnomusicologues du Laboratoire de musicologie comparée et anthropologie de la musique (mcam) de l'Observatoire interdisciplinaire de création et de recherche en musique (oicrm), la professeure Nathalie Fernando soulignait par exemple le peu de recherches ethnomusicologiques portant sur des questions esthétiques dans des sociétés de tradition orale, car les musiques y sont souvent considérées comme étant uniquement fonctionnelles, ce qui a limité les tentatives d'aborder de front les critères du « beau ».Pourtant, les travaux de cette équipe ont su montrer que, malgré le peu de verbalisation dont ils font l'objet, des critères de jugement de goût existent bel et bien dans plusieurs de ces sociétés.Ajoutons que la variabilité du goût, dont a traité le musicologue et sémiologue Jean-Jacques Nattiez lors de sa conférence autour de l'« Essai sur la norme du goût » du philosophe anglais David Hume (1757), n'est pas exclusive à notre contexte sociohistorique ; l'ethnomusicologue Flavia Gervasi, qui travaille sur les chants de la paysannerie dans le Salento, en Italie, a également constaté une hétérogénéité des critères et des conduites sur son propre terrain.
et L'avenir de La critique ?
Pour terminer, quel avenir prédit-on à la critique musicale ?Chez Midgette, la vision était plutôt sombre : non seulement constatait-elle une diminution de l'espace réservé à la musique classique dans la société, mais elle a aussi déploré un changement d'attitude des journaux qui tenteraient désormais de répondre aux attentes des lecteurs plutôt que de les inciter à la découverte.Par conséquent, elle a émis l'hypothèse que les postes de critiques musicaux ne cesseront de diminuer.Du côté de Machart, les interrogations étaient nombreuses et, en grande partie, sans réponses.Elles concernaient tant l'identité des lecteurs-auditeurs (à qui s'adresser ?) que la véritable nature d'une réflexion critique sur la musique.Par ailleurs, l'insistance de ce panéliste sur le rôle de mémoire joué par la critique laisse entendre que cette dernière a sa place et doit continuer d'exister, notamment pour les historiens et musicologues de demain.Finalement, Péloquin a considéré que les transformations actuelles de la critique musicale, notamment par la démultiplication des plates-formes de diffusion, induisent une nouvelle dynamique sociale où il y a, selon lui, « hyperdémocratisation » de la pratique.« Everybody's really a critic » a avancé cet invité, donnant ainsi Le thème de la critique musicale comme telle a ainsi suscité une pluralité de visions et de propositions des panélistes, ce qui n'est certainement pas étranger aux divers contextes -musical, médiatique, mais aussi géographique -au sein desquels ils oeuvrent.Or, la question du goût musical a également parcouru cette discussion, apparaissant au coeur des préoccupations des trois participants.Certaines réflexions communes ont émergé à ce compte, en dépit des différents univers musicaux qu'explorent ces trois critiques, ce qui n'est pas sans rappeler l'idée que les clivages seraient de plus en plus flous entre genres musicaux alors qu'une nouvelle figure de la consommation musicale, la figure de l'« omnivore 5 », s'affirmerait désormais.
Enfin, si la critique telle que pratiquée par les trois invités du panel traverse une période houleuse, il ne s'agit pourtant pas de sa première remise en question dans l'histoire (Duchesneau 2007).De fait, les critiques, ces « miroir[s] grossissant[s] des attitudes et des réactions du public en général » selon le sémiologue Jean Molino (2006Molino ( , p. 1392)), ont souvent vu leur rôle et leur raison d'être débattus.Par ailleurs, il importe de ne pas réduire la critique musicale en soi à sa pratique professionnelle, car si la seconde est souvent remise en question, la première, en ce qu'elle « sous-tend la façon dont nous nous expliquons la musique à nous-mêmes » écrit Griffiths (2004Griffiths ( , p. 1057)), pourra continuer d'exister tant qu'il y aura des auditeurs de la musique.
bibLiograPhie Bangs, Lester (1988) Peterson (voir, entre autres, 1996Peterson (voir, entre autres, , 2004) ) ont initié une série de recherches autour de la question de l'omnivorisme.
«
Panel sur la critique musicale » dans le cadre du colloque international Qu'en est-il du goût musical dans le monde au xxi e siècle ?Revue musicale OICRM, volume 3, n o 1 la personnalité » entourant certains critiques.Extrait vidéo 4 : André Péloquin à propos du critique américain Lester Bangs.Or, il s'avère important de questionner la relation entre une critique musicale et une oeuvre : l'une doit-elle être au service de l'autre ?Y a-t-il rapport d'équilibre, de coexistence, ou plutôt de subordination ?Chez un auteur comme Berthet, le discours critique joue un rôle dans le processus créateur, « la création artistique et [c]e discours […] se rencontr[ant] sur le chemin de la création » (Berthet 2006, p. 8).Or, pour les panélistes Machart et Midgette, il semble que l'oeuvre musicale conserve une certaine primauté et que leurs critiques relèvent davantage du compte rendu.
« Panel sur la critique musicale » dans le cadre du colloque international Qu'en est-il du goût musical dans le monde au xxi e siècle ?domaine de la musique populaire.Il a été chef critique de la section « musique » au journal Voir (août 2012-janvier 2015) et agit à la fois comme chroniqueur, journaliste, réalisateur et recherchiste indépendant (voir son blogue).
Revue musicale OICRM, volume 3, n o 1
« Panel sur la critique musicale » dans le cadre du colloque international Qu'en est-il du goût musical dans le monde au xxi e siècle ?Revue musicale OICRM, volume 3, n o 1 raison à Duchesneau qui parlait en introduction d'une ère où « tout est possible, tout est permis ».
,
Psychotic Reactions and Carburetor Dung.The Work of a Legend Critic.New York, Vintage Books.Bangs, Lester (2003), Main Lines, Blood Feasts, and Bad Taste.A Lester Bangs Reader, New York, Anchor Books.Berthet, Dominique (2006), Les défis de la critique d'art, Paris, Éditions Kimé.Duchesneau, Michel (2007), « Critique musicale et esthétique.Pour un projet d'histoire postmoderne », dans Alessandro Arbo (dir.),Perspectives de l'esthétique musicale.Entre théorie et histoire, Paris, L'Harmattan, p. 177-190.Fernando, Nathalie (2013), « De la variabilité et ou de la similarité des jugements de goût dans les cultures du monde », conférence présentée au colloque Qu'en est-il du goût musical dans le monde au xxi e siècle ?, Montréal, Faculté de musique de l'Université de Montréal, 1 er mars.Gervasi, Flavia (2013), « Les logiques du fonctionnement du discours esthétique chez les chanteurs paysans du Salento.Une exégèse inachevée », conférence présentée au colloque Qu'en est-il du goût musical dans le monde au xxi e siècle ?, Montréal, Faculté de musique de l'Université de Montréal, 1 er mars.Griffiths, Paul (2004), « Objectifs et impacts de la critique musicale », dans Jean-Jacques Nattiez (dir.),Musiques.Encyclopédie pour le xxi e siècle, « 2. Les savoirs musicaux », Arles/Paris, Actes Sud/Cité de la musique, p. 1057-1070.
5Les travaux du sociologue Richard A.
Midgette a donné l'exemple de son mari qui, en tant que professeur à Juilliard, a dû changer le titre de son cours Music Criticism pour Writing About Music étant donné le peu d'enthousiasme des étudiants. 142 Caroline MarCoux-Gendron Revue musicale OICRM, volume 3, n o 1
. Revue musicale OICRM. 31
La norme du goût », trad. fr. par Renée Bouveresse, Essais esthétiques II. Art et psychologie. David Hume, 1974Paris, Vrin
You Call This Fun? Reactions of Young First-time Attendees to a Classical Concert. Bonita M Kolb, Journal of the Music and Entertainment Industry Educators Association. 2000. 10 novembre 2015
The Effect of Generational Change on Classical Music Concert Attendance and Orchestras' Responses in the uk and us. Bonita M Kolb, Cultural Trends. 112001
Pour une autre histoire de la musique. Jean Molino, Les réécritures de l'histoire dans la musique du xx e siècle. Jean-Jacques Nattiez, Arles/ParisActes Sud/Cité de la musique2006Histoires des musiques européennes
Ce que l'essai de Hume sur la norme du goût peut nous apprendre encore aujourd'hui », conférence présentée au colloque Qu'en est-il du goût musical dans le monde au xxi e siècle ?. Jean-Jacques Nattiez, 2013MontréalFaculté de musique de l'Université de Montréal1 er mars
Le développement du public jeune universitaire pour la musique classique à Montréal. Natassja Oliveira-Menezes, Mémoire de maîtrise. 2015Université de Montréal
Changing Highbrow Taste. From Snob to Omnivore. Richard A Peterson, Roger M Et, Kern, American Sociological Review. 611996
Le passage à des goûts omnivores. Notions, faits et perspectives. Richard A Peterson, Sociologie et sociétés. 3612004
| [
-0.032572031021118164,
-0.04747885465621948,
0.03216750919818878,
-0.13267236948013306,
-0.06298519670963287,
0.16513414680957794,
0.04047627002000809,
0.07681949436664581,
0.0483400821685791,
0.06552857160568237,
-0.06530509889125824,
-0.059106484055519104,
0.06179121136665344,
-0.1268058... |
Learning, Generating and Adapting Wave Gestures for Expressive Human-Robot Interaction
Mihalis Panteris mihalis.panteris@mines-paristech.fr
MINES ParisTech Paris
France
Simon Manschitz simon.manschitz@honda-ri.de
Honda Research Institute Europe Offenbach/Main
Germany
Sylvain Calinon sylvain.calinon@idiap.ch
Idiap Research Institute Martigny
Switzerland
Learning, Generating and Adapting Wave Gestures for Expressive Human-Robot Interaction
ACM Reference Format: Mihalis Panteris, Simon Manschitz, and Sylvain Calinon. 2020. Learning, Generating and Adapting Wave Gestures for Expressive Human-Robot Interaction. In Companion of the 2020 ACM/IEEE International Conference on Human-Robot Interaction (HRI '20 Companion), March 23-26, 2020,Cambridge, United Kingdom. ACM, New York, NY, USA, 3 pages. https://doi.org/10.1145/ 3371382.3378286imitation learningmovement primitivessocial robots
This study proposes a novel imitation learning approach for the stochastic generation of human-like rhythmic wave gestures and their modulation for effective non-verbal communication through a probabilistic formulation using joint angle data from human demonstrations. This is achieved by learning and modulating the overall expression characteristics of the gesture (e.g., arm posture, waving frequency and amplitude) in the frequency domain. The method was evaluated on simulated robot experiments involving a robot with a manipulator of 6 degrees of freedom. The results show that the method provides efficient encoding and modulation of rhythmic movements and ensures variability in their execution.
INTRODUCTION
Variability is in the very core of human motor behaviour [3]. While many humanoid robots can perform basic wave gestures, these gestures are usually hard-coded behaviours. Consequently, the gesture looks rather stiff since there is no variance in the execution of the movement. Methods such as probabilistic movement primitives (ProMPs) [2] encode the variability of a movement from a set of demonstrations through a probabilistic trajectory representation. Additionally, ProMPs take advantage of probability distribution properties in order to preserve this variability when adapting the movement to different final positions or via-points. Despite this being straightforward for stroke-based movements, preserving the stochasticity and the variability in the execution of the movement is not possible when modulating rhythmic movements such as wave gestures. In this study we propose that learning should take place in Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for third-party components of this work must be honored. For all other uses, contact the owner/author(s the frequency domain in order to overcome these issues and to efficiently exploit demonstrations of diverse motor patterns. In [1], it was shown that the basis functions used in probabilistic movement primitives do not need to be restricted to radial bases, and can take other forms such as Fourier basis functions. The proposed framework exploits the conditioning property of normal distributions for modulating the gesture. Compute the weight vector w m :
THE PROPOSED LEARNING FRAMEWORK
w m = (Ψ H Ψ) −1 Ψ H y m w r m = |w m | w θ m = Arg(w m ) 6: Fit a Gaussian over the random vector X = ln w r , w θ ⊤ µ x = 1 M M m=1 x m , Σ x = 1 M M m=1 (x m − µ x )(x m − µ x ) ⊤ 7: return µ x , Σ x
We propose here a framework for learning rhythmic movements in joint angle space similar to the one in [2] for stroke-based movements. An overview of the learning method is presented in Algorithm 1. Inspired by Fourier analysis we deploy complex exponential basis functions in the context of movement primitives in order to approximate a trajectory y m of time length T with 2*K conjugate basis functions plus an offset. In vector form this is expressed as:
y m = exp(i 2πtk ⊤ T ) w m = Φ w m (1) With t = [0, 1, ...,T ] ⊤ , k = [−K, −K + 1, ..., K − 1, K] ⊤ and Φ ∈ R T ×(2K +1) .
The above formulation is extended to multidimensional trajectories by using Ψ = Φ ⊗ I , where I is the identity matrix of size D and ⊗ is the Kronecker product. Thus the solution is found by the least squares estimate for complex valued variables. Since the weights w m are complex numbers they can be decomposed to their modulus w r and phase w θ components. The representation of the complex weights in polar coordinates enables us to modulate intuitively the movement in terms of frequency, amplitude or phase. The modulus is a non-negative number and thus must be bounded in zero. By assuming that the least squares estimate of the weights yields non-zero values we can compute the principal value of the logarithm of w:
ln w = ln w r + i w θ ,
where w θ ∈ (−π , π ], and fit a joint normal distribution over its real and imaginary parts, i.e fit a normal distribution over the random vector X = ln w r , w θ ⊤ . Through this distribution we can stochastically generate wave gestures by sampling over N (µ x , Σ x ) and then synthesize the resulting trajectory according to (1):
y s = Ψ exp ln w r exp i w θ(2)
When the offsets w 0 of the demonstrations have both negative and positive sign, a normal distribution should be fitted on the random vector X = ln w r , w θ , w 0 ⊤ instead. Similarly to [2] where the conditional probability property is exploited to modulate the trajectory in joint angle space, we modulate the wave gesture in the weight space by conditioning on a subset of the random vector X . Contrary to ProMPs a trajectory distribution can not be defined since y is not a linear transformation of X .
EXPERIMENTAL RESULTS
We recorded 15 demonstrations of various postures and waving patterns with frequencies ranging between 1.5 and 3 Hz. The maximum number of oscillations per demonstration is 20 and thus we use K=25 conjugate basis functions for training. We use the movement data of the arm by taking into account D=5 degrees of freedom for training. We test the modulation capacity of the model by conditioning first on the random variable that corresponds to the amplitude of the 10th harmonic of the elbow joint and then on the 20th harmonic of the wrist joint. We observe the retrieved µ w r |w r k =10, el bow = 5 and µ w r |w r k =20,w r is t = 4 . The model is able to infer that a rhythmic movement of 10 elbow cycles should be accompanied by equivalent wrist cycles of similar amplitude and that for 20 wrist cycles the movement of the elbow should have low amplitude and higher frequency. Fig.1 shows the effect of modulation on the elbow and wrist joints in the frequency domain. Zero frequency terms are omitted for convenience of illustration. Fig.2 demonstrates the ability to preserve the stochastic variability of the generated movement in terms of posture, frequency, amplitude and phase during its modulation. Finally, we test the method on simulated robot experiments involving a robot with a manipulator of 6 degrees of freedom. The results are depicted in Fig.3 and demonstrate the ability to execute various human-like wave gestures.
CONCLUSION
Using the probabilistic movement primitives framework as a baseline we discussed a novel approach for the efficient learning and modulation of rhythmic movements through a probabilistic formulation. The proposed framework draws inspiration from the decomposition of signals as Fourier series, and extends ProMPs in the frequency domain by using complex exponential basis functions. The framework provides the structure needed in order to exploit the conditioning property for modulating rhythmic movements in an intuitive way, which was not possible in the original ProMPs framework. Albeit, these advantages come at the cost of abandoning the definition of a trajectory distribution which limits the modulation capacity of the framework to motions without a specific target in task space. Future work could include a user-based study of the naturalness of the generated gestures in comparison with existing motion generation methods in real robot experiments.
Data: a set of M trajectories y of time length T and dimension D in joint angle space. 2: Input: number of conjugate basis functions K 3: for each trajectory m do 4: Generate basis functions: Ψ = f (t, K,T , D) 5:
Figure 1 :
1Mean of the single sided spectrum of the demonstrations (µ w r ) in black. Frequency modulation of the elbow joint in green. Frequency modulation of the wrist joint in red.
Figure 2 :
2Trajectory samples of the same conditional distribution in red and blue. Modulation by conditioning generates similar motor patterns but different movements.
Figure 3 :
3Overlaid images of the resulting waving patterns in simulated robot experiments. Left: Conditioning on the elbow joint. Right: Conditioning on the wrist joint.
ACKNOWLEDGMENTSThis work was supported by Honda Research Institute Europe.
Mixture Models for the Analysis, Edition, and Synthesis of Continuous Time Series. S Calinon, 10.1007/978-3-030-23876-6_3Mixture Models and Applications, N. Bouguila and W. FanSpringerS. Calinon. 2019. Mixture Models for the Analysis, Edition, and Synthesis of Continuous Time Series. In Mixture Models and Applications, N. Bouguila and W. Fan (Eds.). Springer, 39-57. https://doi.org/10.1007/978-3-030-23876-6_3
Using probabilistic movement primitives in robotics. Alexandros Paraschos, Christian Daniel, Jan Peters, Gerhard Neumann, 10.1007/s10514-017-9648-7Autonomous Robots. 42Alexandros Paraschos, Christian Daniel, Jan Peters, and Gerhard Neumann. 2018. Using probabilistic movement primitives in robotics. Autonomous Robots 42, 3 (Mar 2018), 529-551. https://doi.org/10.1007/s10514-017-9648-7
Optimal Movement Variability: A New Theoretical Perspective for Neurologic Physical Therapy. Nicholas Stergiou, Regina T Harbourne, James T Cavanaugh, 10.1097/01.NPT.0000281949.48193.d9Journal of Neurologic Physical Therapy. 303Nicholas Stergiou, Regina T. Harbourne, and James T. Cavanaugh. 2006. Optimal Movement Variability: A New Theoretical Perspective for Neurologic Physical Therapy. Journal of Neurologic Physical Therapy 30, 3 (September 2006), 120-129. https://doi.org/10.1097/01.NPT.0000281949.48193.d9
| [
-0.10850344598293304,
-0.20642228424549103,
0.07206617295742035,
-0.1518949270248413,
-0.041556987911462784,
-0.09208160638809204,
0.06341303139925003,
-0.03051326610147953,
-0.06533551216125488,
0.0033366247080266476,
0.09816249459981918,
-0.15488579869270325,
0.03898896649479866,
-0.0242... |
GENERATION AND INITIAL CHARACTERIZATION OF A COLLECTION OF SPONTANEOUS STREPTOMYCES ALBUS J1074 MUTANTS RESISTANT TO RIFAMPICIN
Ostash B O
Misaki Y
Dolya B
Kharaton Y
Busche T
Luzhetskyy A
Kalinowski J
Ochi K
Fedorenko V O viktor.fedorenko@lnu.edu.ua@38032239-44-75
© Ostash
Ivan Franko National University of Lviv
79005LvivHrushevskohoUkraine
Hiroshima Institute of Technology
Saeki-ku731-5193HiroshimaJapan
Center for Biotechnology
Bielefeld University
Germany, Bielefeld
University of Saarland
66123Germany, Saarbrьcken
University Campus
C2.3Building
MISAKI Y., DOLYA B., KHARATONB O
Y
Busche T
Luzhetskyy A
Kalinowski J
Ochi K
Fedorenko V O
GENERATION AND INITIAL CHARACTERIZATION OF A COLLECTION OF SPONTANEOUS STREPTOMYCES ALBUS J1074 MUTANTS RESISTANT TO RIFAMPICIN
10.7124/FEEO.v27.1316(Online), ISSN 2219-3782 (Print). Фактори експериментальної еволюції організмів 2020. Том 27 139
Streptomyces albus J1074 (also known as S. albidoflavus J1074) is one of the most versatile and genetically amenable streptomycetes widely used for drug discovery purposes [1]. The range of applications includes heterologous expression of gene clusters and metagenomic libraries; incorporation of unnatural amino acids into ribosomally produced peptides; generation of whole-cell biosensor systems. NPs are produced by the wild type and heterologous streptomycete hosts in low yields, and this shortcoming pertains to J1074 as well. It prompts the interest in strain improvement investigations. Introduction of certain antibiotic resistance mutations into Streptomyces genomes has long been known to improve NP biosynthesis. Most of these mutations alter the function of ribosome (streptomycin, paromomycin, thiostrepton resistance) or β subunit of RNA polymerase (RpoB; rifampicin resistance); the approaches based on these mutations were collectively referred to as ribosome engineering [2]. We recently developed a rational genome engineering method to introduce point mutations into the genes usually targeted by the ribosome engineering, e.g. rpsL for S12 ribosomal protein [3]. This led to a collection of J1074 rpsL mutants with variable levels of activation of their indigenous secondary metabolism. The rpsL mutant carrying R94G substitution turned out to be one of the most productive (A. Luzhetskyy, unpublished), prompting us to generate S. albus strain carrying this allele in merodiploid state (e.g. rpsL and rpsL R94G alleles co-exist in J1074 chromosome; the latter was introduced on integrative actinophage VWB-based vector pTOS [4]). It is important to note that R94G allele is one of those rpsL mutations that do not lead to increased aminoglycoside resistance. As the accumulation of several different resistance mutations in single genome is known to provide further increases in NP titers [2], we used R94G strains as a starting point to generate strains resistant to streptomycin, lincomycin and erythromycin. As a result, we picked quadruple pure rpsL mutant KO-1305 (rpsL R94G rsmG (Str r ) Lin r Ery r ) and merodiploid mutant KO-1307 (rpsL rpsL R94G rsmG (Str r ) Lin r Ery r ). The aforementioned strains exhibited increased antibiotic activity against Staphylococcus albus P209; their characterization will be reported elsewhere. Here we describe the generation of spontaneous rifampicin-resistant derivatives of KO-1305 and KO-1307 and their initial characterization.
Materials and methods
S. albus SAM2, a J1074 derivative with deletion of φC31 pseudo attB site [5], was used throughout the work. The genealogy of S. albus strains mentioned in this work is given in Fig. 1. Staph. aureus 209P, Bacillus cereus ATCC19637, Debaryomyces hansenii VKM Y-9 were used in the bioassays as test cultures. We selected Rif r variants on GYM agar [6] with 10 μg/mL of rifampicin. Antibiotic resistance and activity assays, sequencing of rpoB alleles were carried out as described in [7]. The other bioassay conditions and media are described in [6]. KO-1408 genome has been sequenced using Illumina approach essentially as described in [8]. The quality control stage the sequence reads was performed by using FastQC (http://www.bioinformatics.babraham.ac.uk/project s/fastqc). Raw Illumina short reads were qualitytrimmed with Trimmomatic v.0.36 [9]. Sequencing reads were aligned to reference J1074 genome (accession number NC_020990) with Bowtie2 v.2.2.5. SNP and DIP detection was performed by means of ReadXplorer [10]. Only the SNVs and indels different from those found in SAM2 were considered true mutations in KO-1408. BLAST search tools were used to identify genes of interest in the genomes of S. albus J1074 and its derivatives.
Results and discussion
The spores of S. albus KO-1305 and KO-1307 strains were spread and incubated on GYM plates supplemented with 10 μg/mL rifampicin, and Rif r mutants were observed after 3 to 7 days at a frequency of 10 −7 to 10 −8 . After three passages under nonselective conditions the resulting mutants (about 80 clones) were again plated onto Rifcontaining agar; all strains exhibited abundant growth. This confirmed the stability of their Rif r phenotype. Most often the Rif r phenotype arises from mutations in rpoB gene for the RNA polymerase (RNAP) β-subunit; hence we amplified rpoB (xnr_3712) from our mutants. In all but one cases the rif mutations were located within the so called "rif cluster" of RNAP, encompassing the 422-443 amino acid stretch. The only exception was KO-1412, which was revealed to carry missense mutation within rpoB leading to Pro475 Leu substitution. Along with this mutation, two other novel mutations within "rif cluster" were uncovered: Ser433 Trp (KO-1403) and Arg440 Cys (KO-1407). We used spore dilution spot tests to determine Rif resistance level of the mutants; these data, along with sequencing results, are summarized in Table. We assayed the endogenous antibiotic activity of selected KO strains using several test cultures (see Materials and methods), GYM and SG2 media, and agar plug tests. Overall, although some merodiploid-based Rif r strains showed greater activity as compared to their parent (R94G_ex) against S. aureus 209P, they were less active than KO strains derived from pure R94G rpsL mutant. One notable exception is KO-1412 carrying novel P475L mutation; it showed increased antibiotic activity after 5 days of cultivation in GYM (15-mm halo of 209P growth inhibition), while the parental strain R94G_ex showed almost no activity. Similar trend was observed when GYM-grown agar plugs of the KO strains were assayed against B. cereus (Fig. 2). Notes: * Highlighted cells correspond to substitutions that are, to the best of our knowledge [2,7], observed for the first time in Streptomyces; ** Number of mutants out of total Rif r clones isolated from a given KO strain. ▼ Parental strain for respective Rif r lineages. No changes in antifungal activity have been observed for the KO strains as compared to parental ones. After a series of bioassays, we have come to conclusion that the mutant KO-1408 (R440H) exhibits the most robust increase in endogenous antibacterial activity, which is evident under different cultivation conditions and against different test cultures. Significantly, this increase appeared to be due to the presence of rpsL R94G allele in haploid ("pure") state, since isogenic rpoB R440H mutation in merodiploid rpsL+rpsL R94G background (KO-1417) did not result in comparable increase in antibiotic activity (Fig. 2).
Next we focused on KO-1408. First, we compared the antibiotic activity of strain lineage leading to KO-1408. The bioassays support the idea that rif mutation leading to rpoB R440H was a major one that induced antibacterial production by KO-1408. Indeed, initial strain R94G (carrying rpsL R94G allele) had no major effect on antibacterial activity under our cultivation conditions (Fig. 3), and following Str r , Lin r , Ery r mutations had no effect as well (data not shown).
One caveat is that spontaneous mutants could carry additional as-yet-unknown mutations in their genome which may contribute to the final antibiotic resistance and activity phenotypes. To rule out this scenario for KO-1408, we sequenced its genome as well as genomes of SAM2, R94G, KO-1295, KO-1304 and KO-1305. We revealed no new mutations in KO-1408 as compared to KO-1305, except for already known one leading to rpoB R440H allele. Therefore, the augmented antibiotic potency of KO-1408 most likely stems from a combination of known rpsL R94G and rpoB R440H mutations.
Conclusions
S. albus J1074 attracts interest of academic and industrial researchers as a reliable platform for drug discovery. In this work we describe a set of rifampicin resistant mutants on the basis of multiply antibiotic resistant S. albus KO-1305 and KO-1307 strains. Some of the identified Rif r mutations within rpoB were not previously reported, raising the possibility that rpoB mutational space leading to Rif resistance is not fully understood despite decades of research. Nevertheless, well-known rpoB R440H turned out to be the most effective in terms of enhancement of secondary metabolism of S. albus. It remains to be studied the production of what compounds is activated in KO-1408 and other strains; and whether these mutants will support the increased production of compounds directed by heterologous BGCs. Experiments are underway in our laboratories to address these questions.
Fig. 1 .
1Scheme of generation of spontaneous Rif r mutants KO1401-KO1417 (bottom of the figure).Abbreviations: StrR, resistance to streptomycin; LinR, resistance to lincomycin; EryR, resistance to erythromycin. Other abbreviations and strain names, please see the main text.
Fig. 2 .
2Halos of B. cereus ATCC19637 growth inhibition around agar plugs of the KO strains cultivated for five days on SG2 agar.
Fig. 3 .
3Halos of B. cereus ATCC19637 growth inhibition around agar plugs of the B29 (paulomycin-deficient derivative of J1074[11]), R94G, SAM2 and KO-1408 strains. Growth conditions, seeFig. 2. For each strain three agar plugs from different plates were assayed.
Table .
.Mutations and rifampicin resistance levels of various of rpoB mutants isolated from S. albus KO-1305 and KO-1307Strain
Mutation in rpoB
Amino acid
substitution*
Mutant
frequency**
Rif resistance
(μg/mL)
J1074
-
-
-
3
KO-1305 ▼
-
-
-
3
KO-1401
1325C→T
Ser442→Leu
1/48
30
KO-1402
1262C-1273T→Δ
Q421-F425→L421
1/48
200
KO-1403
1298G→C
Ser433→Trp
1/48
10
KO-1404
1310A→G
His437→Arg
13/48
>200
KO-1405
1309C→T
His437→Tyr
15/48
200
KO-1406
1318C→A
Arg440→Ser
1/48
20
KO-1407
1318C→T
Arg440→Cys
5/48
25
KO-1408
1319G→A
Arg440→His
7/48
25
KO-1409
1271A→T
Gln424→Leu
2/48
200
KO-1307 ▼
-
-
-
3
KO-1410
1325C→T
Ser433→Leu
1/37
25
KO-1411
1310A→G
His437→Arg
12/37
>200
KO-1412
1451C→T
Pro475→Leu
1/37
25
KO-1413
1309C→T
His437→Tyr
16/37
200
KO-1414
1309C→G
His437→Asp
3/37
100
KO-1415
1271A→T
Gln424→Leu
1/37
50
KO-1416
1310A→C
His437→Pro
1/37
>200
KO-1417
1319G→A
Arg440→His
1/37
25
This work was supported by grants F60-2015 from State Fund for Fundamental Research of Ukraine and BG-80F from Ministry of Education and Science of Ukraine (both to B.O.). C. Olano (Oviedo University) is thanked for gift of ∆B29S. albus strain.ОСТАШ Б.О. 1 , МІСАКІ Ю. 2 , ДОЛЯ Б.С. 1 , ХАРАТОН Я.І. 1 , БУШЕ T.3КОНСТРУЮВАННЯ І ВИХІДНА ХАРАКТЕРИСТИКА КОЛЕКЦІЇ СПОНТАННИХ МУТАНТІВ STREPTOMYCES ALBUS J1074 СТІЙКИХ ДО РИФАМПІЦИНУМета. Streptomyces albus J1074 -одна із найпопулярніших стрептоміцетних платформ для гетерологічної експресії кластерів генів біосинтезу природних сполук. Становить інтерес у дослідженнях, які б вели до підвищених кількостей продукції відповідних сполук. Уведення певних типів мутацій стійкості до антибіотиків -доведений шлях селекції штамів Streptomyces. Наприклад, селекція за стійкістю до рифампіцину веде до зростання антибіотичної активності. У цій роботі ми використали наявні лінії антибіотикорезистентні лінії S. albus для отримання рифампіцин-стійких варіантів (Rif r ) та їхнього вивчення. Mетоди. Застосовано мiкробіологічні та молекулярно-генетичні підходи для селекції Rif r мутантів та вивчення їхніх властивостей. Результати. Виділено 85 стабільних Rif r клонів, чия резистентність була у межах 10-200 мкг/мл. Секвенування виявило широкий спектр міссенс-мутацій у межах гена rpoB. Біотести виявили сильне зростання ендогенної антибіотичної активності деяких Rif r мутантів. Висновки. Селекція за стійкістю до рифампіцинуперспективний спосіб селекції високопродуктивних штамів S. albus. Ключові слова: Streptomyces albus J1074, стійкість до антибіотиків, рифампіцин.
Heterologous production of small molecules in the optimized Streptomyces hosts. M Myronovskyi, A Luzhetskyy, 10.1039/c9np00023bNat. Prod. Rep. 36Myronovskyi M., Luzhetskyy A. Heterologous production of small molecules in the optimized Streptomyces hosts. Nat. Prod. Rep. 2019. Vol. 36. P. 1281-1294. doi: 10.1039/c9np00023b.
Insights into microbial cryptic gene activation and strain improvement: principle, application and technical aspects. K Ochi, 10.1038/ja.2016.82J. Antibiot. 70Ochi K. Insights into microbial cryptic gene activation and strain improvement: principle, application and technical aspects. J. Antibiot. 2017. Vol. 70. P. 25-40. doi: 10.1038/ja.2016.82.
Effect of "ribosome engineering" on the transcription level and production of S. albus indigenous secondary metabolites. M Lopatniuk, M Myronovskyi, A Nottebrock, T Busche, J Kalinowski, B Ostash, V Fedorenko, A Luzhetskyy, 10.1007/s00253-019-10005-yAppl. Microbiol. Biotechnol. 103Lopatniuk M., Myronovskyi M., Nottebrock A., Busche T., Kalinowski J., Ostash B., Fedorenko V., Luzhetskyy A. Effect of "ribosome engineering" on the transcription level and production of S. albus indigenous secondary metabolites. Appl. Microbiol. Biotechnol. 2019. Vol. 103. P. 7097-7110. doi: 10.1007/s00253-019-10005-y.
Actinomycetes genome engineering approaches. T Siegl, A Luzhetskyy, Antonie Van Leeuwenhoek. 102Siegl T., Luzhetskyy A. Actinomycetes genome engineering approaches. Antonie Van Leeuwenhoek. 2012. Vol. 102. P. 503- 516.
Unusual site-specific DNA integration into the highly active pseudo-attB of the Streptomyces albus J1074 genome. B Bilyk, A Luzhetskyy, 10.1007/s00253-014-5605-yAppl. Microbiol. Biotechnol. 98Bilyk B., Luzhetskyy A. Unusual site-specific DNA integration into the highly active pseudo-attB of the Streptomyces albus J1074 genome. Appl. Microbiol. Biotechnol. 2014. Vol. 98. P. 5095-5104. doi: 10.1007/s00253-014-5605-y.
Properties of Streptomyces albus J1074 mutant deficient in tRNA Leu UAA gene bldA. O Koshla, M Lopatniuk, I Rokytskyy, O Yushchuk, Y Dacyuk, V Fedorenko, A Luzhetskyy, B Ostash, 10.1007/s00203-017-1389-7Arch. Microbiol. 199Koshla O., Lopatniuk M., Rokytskyy I., Yushchuk O., Dacyuk Y., Fedorenko V., Luzhetskyy A., Ostash B. Properties of Streptomyces albus J1074 mutant deficient in tRNA Leu UAA gene bldA. Arch. Microbiol. 2017. Vol. 199. P. 1175-1183. doi: 10.1007/s00203-017-1389-7.
Activation and products of the cryptic secondary metabolite biosynthetic gene clusters by rifampin resistance (rpoB) mutations in actinomycetes. Y Tanaka, K Kasahara, Y Hirose, K Murakami, R Kugimiya, K Ochi, 10.1128/JB.00147-13J. Bacteriol. 195Tanaka Y., Kasahara K., Hirose Y., Murakami K., Kugimiya R., Ochi K. Activation and products of the cryptic secondary metabolite biosynthetic gene clusters by rifampin resistance (rpoB) mutations in actinomycetes. J. Bacteriol. 2013. Vol. 195. P. 2959-2970. doi: 10.1128/JB.00147-13.
Heterologous AdpA transcription factors enhance landomycin production in Streptomyces cyanogenus S136 under a broad range of growth conditions. O Yushchuk, I Ostash, I Vlasiuk, T Gren, A Luzhetskyy, J Kalinowski, V Fedorenko, B Ostash, 10.1007/s00253-018-9249-1Appl. Microbiol. Biotechnol. 102Yushchuk O., Ostash I., Vlasiuk I., Gren T., Luzhetskyy A., Kalinowski J., Fedorenko V., Ostash B. Heterologous AdpA transcription factors enhance landomycin production in Streptomyces cyanogenus S136 under a broad range of growth conditions. Appl. Microbiol. Biotechnol. 2018. Vol. 102. P. 8419-8428. doi: 10.1007/s00253-018-9249-1.
Trimmomatic: a flexible trimmer for Illumina sequence data. A M Bolger, M Lohse, B Usadel, 10.1093/bioinformatics/btu170Bioinformatics. 30Bolger A.M., Lohse M., Usadel B. Trimmomatic: a flexible trimmer for Illumina sequence data. Bioinformatics. 2014. Vol. 30. P. 2114-2120. doi: 10.1093/bioinformatics/btu170.
ReadXplorer -visualization and analysis of mapped sequences. R Hilker, K B Stadermann, D Doppmeier, J Kalinowski, J Stoye, J Straube, 10.1093/bioinformatics/btu205Bioinformatics. 30Hilker R., Stadermann K. B., Doppmeier D., Kalinowski J., Stoye, J. Straube, J., et al. ReadXplorer -visualization and analysis of mapped sequences. Bioinformatics. 2014. Vol. 30. P. 2247-2254. doi: 10.1093/bioinformatics/btu205.
Activation and identification of five clusters for secondary metabolites in Streptomyces albus J1074. C Olano, I Garcнa, A Gonzбlez, 10.1111/1751-7915.12116Microb Biotechnol. 7Olano C., Garcнa I., Gonzбlez A., et al. Activation and identification of five clusters for secondary metabolites in Streptomyces albus J1074. Microb Biotechnol. 2014. Vol. 7. P. 242-256. doi:10.1111/1751-7915.12116.
| [
-0.07849165797233582,
-0.1619274616241455,
-0.2730717062950134,
-0.07618898153305054,
0.01401089783757925,
0.05710907652974129,
-0.21987920999526978,
0.17867746949195862,
0.0937359482049942,
-0.03144330531358719,
0.018146535381674767,
-0.034889187663793564,
0.11053065955638885,
0.176169469... |
Year 2022 Global Journal of Medical Research Volume XXII Issue II Version I Year 2022 Global Journal of Medical Research Volume XXII Issue II Version I
Pedro Augusto
Cruz Correia
Matheus Santos matheusmarques@fainor.com.br
Marques
Curso de Farmácia
Faculdade Independente do Nordeste -FAINOR
Av. Luís Eduardo Magalhães, 1305 -Candeias
Curso de Farmácia
Vitória da Conquista -BA
Faculdade Independente do Nordeste -FAINOR, Av. Luís Eduardo Magalhães, 1305 -Candeias, Vitória da Conquista -BA, 45055-03045055-030
Year 2022 Global Journal of Medical Research Volume XXII Issue II Version I Year 2022 Global Journal of Medical Research Volume XXII Issue II Version I
This research/review article is distributed under the terms of the Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). You must give appropriate credit to authors and reference this article if parts of the article are reproduced in any manner. Applicable licensing terms are at https://creativecommons.org/licenses/by-nc-nd/4.0/. Determinação Do Perfil De Prescrição De Oxandrolona E Estanazolol Em Farmácias De Manipulação De Vitória Da Conquista No Ano De 2019 GJMR-C Classification: DDC Code: 362.29088796 LCC Code: RC1230 DeterminacaoDoPerfilDePrescricaoDeOxandrolonaEEstanazololEmFarmaciasDeManipulacaoDeVitoriaDaConquistaNoAnoDe2019 Strictly as per the compliance and regulations of: Global Journal of Medical Research: C Microbiology and Pathology Volume 22 Issue 2 Version 1.0 Year 2022 Type: Double Blind Peer Reviewed International Research Journal Publisher: Global Journals Online ISSN: 2249-4618 & Print Author α: Corresponding Author σ: ( D D D D ) C ( D D D D ) C © 2022 Global Journals Determinação Do Perfil De Prescrição De Oxandrolona E Estanazolol Em Farmácias De Manipulação De Vitória Da Conquista No Ano De 2019 9 Year 2022 ( D D D D ) C © 2022 Global Journals Determinação Do Perfil De Prescrição De Oxandrolona E Estanazolol Em Farmácias De Manipulação De Vitória Da Conquista No Ano De 2019 12 ( D D D D ) C © 2022 Global Journals Determinação Do Perfil De Prescrição De Oxandrolona E Estanazolol Em Farmácias De Manipulação De Vitória Da Conquista No Ano De 2019 13 ( D D D D ) C © 2022 Global Journals Determinação Do Perfil De Prescrição De Oxandrolona E Estanazolol Em Farmácias De Manipulação De Vitória Da Conquista No Ano De 2019anabolic steroids specialty prescribers
Anabolic androgenic steroids (AAS) are synthetic substances produced from the hormone testosterone. Among some of the AASs used, are the substances oxandrolone and stanazolol, which can be prescribed in order to obtain results in sports or for therapeutic purposes. Although they demonstrate benefits, the great concern regarding the use of these substances is due to the large number of possible adverse effects. With that said, the present research was formulated with the intention of making a study about the use of anabolic steroids in manipulation pharmacies, and to determine its use profile, the pharmaceutical form and the dosage, to identify the reasons that lead to the use of steroids, and identify the prescriber's specialization and relate it to its use.
Resumo-Os esteroides anabolizantes androgênicos (EAA) são substâncias sintéticas produzidas a partir do hormônio testosterona. Entre alguns dos EAAs utilizados, estão as substâncias oxandrolona e estanazolol, que podem ser prescritas com intuito de obter resultados no meio desportivo ou para fins terapêuticos. Embora demonstrem benefícios, a grande preocupação em relação ao uso destas substâncias se deve à grande quantidade de efeitos adversos possíveis. Diante disso, a presente pesquisa foi formulada com o intuito de fazer um estudo a respeito do uso de esteroides anabolizantes em farmácias de manipulação, e determinar o seu perfil de uso, a forma farmacêutica e a dosagem, identificar os motivos que levam ao uso dos esteroides, e identificar a especialização do prescritor e relacionar ao seu uso. A pesquisa foi realizada na maior rede de farmácias de manipulação da cidade de Vitória da Conquista, onde foram coletadas todas as ordens de manipulação que continham as substâncias oxandrolona e estanazolol durante o período do ano de 2019, e foi encontrado um total de 542 ordens de manipulação, sendo que a oxandrolona foi muito mais utilizada que o estanazolol, 58,3% dos pacientes pertenciam ao sexo feminino, e 84,9% dos médicos prescritores foram generalistas. A forma mais utilizada foi em cápsulas por via oral, e a dosagem mais frequente foi a de 10mg para as duas drogas. A grande quantidade de médicos generalistas que prescrevem anabolizantes mostrou-se um dado preocupante, devido aos diversos problemas acarretados quando ocorre o uso dessas drogas de forma desnecessária. O conhecimento sobre anabolizantes é de extrema importância para a prevenção do seu uso indevido, por isso espera-se que profissionais especializados só utilizem tais substâncias em casos de terapia onde são de fato necessárias.
Palavras-Chave: esteroides anabolizantes. especialidade. prescritores. Abstract-Anabolic androgenic steroids (AAS) are synthetic substances produced from the hormone testosterone. Among some of the AASs used, are the substances oxandrolone and stanazolol, which can be prescribed in order to obtain results in sports or for therapeutic purposes. Although they demonstrate benefits, the great concern regarding the use of these substances is due to the large number of possible adverse effects. With that said, the present research was formulated with the intention of making a study about the use of anabolic steroids in manipulation pharmacies, and to determine its use profile, the pharmaceutical form and the dosage, to identify the reasons that lead to the use of steroids, and identify the prescriber's specialization and relate it to its use. The research was carried out in the largest network of manipulation pharmacies in the city of Vitória da Conquista, where all manipulation orders containing the substances oxandrolone and stanazolol were collected during the period of the year 2019, and a total of 542 manipulation orders were found, with oxandrolone being much more used than stanazolol, 58.3% of patients were female, and 84.9% of prescribers were generalists. The most used form was in oral capsules, and the most frequent dosage was 10mg for both drugs. The large number of general physicians who prescribe anabolic steroids proved to be a worrying fact, due to the various problems caused when these drugs are used unnecessarily. Knowledge about anabolic steroids is extremely important to prevent their misuse, and so it is expected that specialized physicians will only use these substances in cases of therapy where they are really necessary.
Keywords: anabolic steroids. specialty. prescribers.
I.
Introdução s esteroides anabolizantes androgênicos (EAA) são substâncias sintéticas produzidas a partir do hormônio testosterona. Essas substâncias foram inicialmente sintetizadas para diversos fins terapêuticos, mas devido ao fato de possuírem efeitos sobre o aumento da síntese proteica e a melhora nas reservas de energia e recuperação musculares após treinamento físico, passaram a ser utilizados por atletas para melhorar o desempenho esportivo (LIMA, et al, 2015). Essas drogas proporcionam a melhoria do desempenho durante exercícios físicos, com aumento de massa muscular, perda de gordura e também agem na melhora em questões estéticas. (MARKOVICZ, 2019). Entre alguns dos EAAs utilizados, estão as substâncias oxandrolona e estanazolol, moléculas modificadas a partir da testosterona, que podem ser prescritas com intuito de obter resultados no meio desportivo ou para fins terapêuticos (MARKOVICZ, 2019). Embora demonstrem benefícios, a grande O preocupação em relação ao uso destas substâncias se deve à grande quantidade de efeitos adversos possíveis, em diversos órgãos e sistemas, além dos efeitos psicológicos, incluindo mudanças de humor, comportamento agressivo, depressão, hostilidade e surtos psicóticos (LIMA, et al, 2015).
Diante de tais afirmações, a presente pesquisa foi formulada com o intuito de fazer um estudo a respeito do uso de esteroides anabolizantes em farmácias de manipulação, onde estas drogas só podem ser obtidas por meio legal e documentado. A pesquisa traz impacto para os usuários de esteroides anabolizantes ao voltar a atenção aos seus diversos riscos, devido à grande quantidade de efeitos adversos provocados por essas drogas, e se mostra oportuna nesse momento visto que o consumo no Brasil demonstra ser elevado, acreditando-se estar concentrado em jovens do sexo masculino com faixa etária de 18-34 anos, englobando praticantes de esporte, principalmente musculação, sendo que no Brasil, 8-55% dos frequentadores de academia fazem uso de anabolizantes (FARIA, et al, 2015). O estudo desse tema mostra-se relevante para a área de farmácia pois permite avaliar a necessidade do uso dessas drogas e se não existem outras alternativas terapêuticas menos danosas para o alcance do objetivo do paciente.
As farmácias pesquisadas fazem parte da maior rede da cidade, que contém uma matriz e quatro filiais, distribuídas nos dois grandes lados da cidade (oeste e leste), próxima dos grandes centros médicos e hospitais e com elevada demanda de produtos. Os EAA disponíveis para venda nas farmácias em questão são a oxandrolona e estanazolol, e a partir das prescrições contendo essas drogas pretende-se determinar o seu perfil de uso, a forma farmacêutica e a dosagem, identificar os motivos que levam ao uso dos esteroides, e identificar a especialização do prescritor e relacionar ao seu uso.
II.
Metodologia
A pesquisa foi realizada na maior rede de farmácias de manipulação da cidade de Vitória da Conquista, que conta com cinco farmácias, onde foram coletadas todas as ordens de manipulação que contêm as substâncias oxandrolona e estanazolol durante o período de um ano, entre os meses janeiro a dezembro de 2019.
A coleta de dados foi realizada de forma digital, por meio da obtenção de arquivos contendo as ordens de manipulação de oxandrolona e estanazolol de cada uma das farmácias, seguida do armazenamento em pen-drive e computador para posterior leitura e tabulação dos dados. Uma ordem de manipulação é uma ficha impressa que determina as quantidades de matéria prima, embalagem, excipientes, entre outras informações relevantes que identifiquem e caracterizem o procedimento a ser realizado numa formulação. A amostra estudada se tratou de usuários destas substâncias.
Os dados coletados a partir das ordens de manipulação englobam o perfil dos usuários, sendo que entre as informações estavam o sexo dos pacientes, número de registro no conselho regional de medicina (CRM) do médico, forma farmacêutica e dosagem da substância. O CRM de cada médico foi o dado utilizado para encontrar as especialidades dos médicos pesquisados. Isso foi possível já que todo profissional formado em medicina deve ter registro no conselho federal de medicina (CFM), que é o órgão por fiscalizar e normatizar a prática médica. O CFM possui um website onde há uma aba que permite ao cidadão comum realizar a pesquisa por qualquer médico utilizando o seu CRM, que então informa a especialidade do médico. Dessa forma, houve o intuito de utilizar esses dados para identificar qual especialidade médica é responsável pelo maior número de prescrições de esteroides anabolizantes na farmácia de manipulação, bem como discutir as possíveis finalidades do uso da droga.
Após a obtenção dos dados, utilizou-se o programa de análise estatística SPSS para realizar a organização e formar tabelas com os mesmos.
III.
Resultados e Discussão
Foi encontrado um total de 542 ordens de manipulação contendo oxandrolona e estanazolol ao longo do período de 2019, sendo que a maioria dos pacientes que usaram a substância foram do sexo feminino. A tabela 1 a seguir mostra a frequência de prescrição das drogas: Fonte: autor A partir dos dados coletados, percebe-se que a grande maioria dos médicos prescritores (84,9%) são generalistas, não possuindo especialização registrada no CFM em qualquer área que os tornem mais capacitados para realizar a prescrição segura dos esteroides anabolizantes, sejam esses para o uso terapêutico ou para o uso desportivo. A associação entre as especialidades e possíveis usos das drogas será discutida mais a frente com a tabela 3.
Dos médicos especialistas, a maioria tem especialidade em urologia, seguido de cirurgia geral e radiologia, depois por endocrinologia e pediatria. Os EAA também estavam acompanhados a diversas drogas associadas em várias prescrições, incluindo por exemplo antioxidantes e antineoplásicos, mas a maioria se tratava de suplementos dietéticos, aminoácidos, e substâncias que auxiliam em perda de peso ou estímulo do apetite, o que indica um perfil de uso com fins estéticos e/ou desportivos. Já no caso de utilizações terapêuticas, os esteroides podem auxiliar no tratamento de diversos problemas, como osteoporose, disfunções de crescimento, tratamento de queimaduras graves (MARKOVICZ, 2019), patologias em que há déficit de testosterona, balanço proteico negativo, câncer de mama, angiodema hereditário, anemia aplástica, endometriose grave, estímulo do crescimento em caso de puberdade masculina tardia, insuficiência renal aguda e mielofibrose (FARIA, et al, 2015).
Dessa forma, percebe-se que algumas das especialidades presentes justificam o uso dos EAA para utilizações terapêuticas. Segundo Markovicz (2019) e Faria (2015), essas drogas podem ser utilizadas no tratamento de diversas patologias, que podem então ser associadas com as especialidades prescritoras, conforme demonstra a tabela 3: Caso os profissionais em questão tenham realizado a prescrição com intuito terapêutico, ainda assim percebe-se que as especialidades anestesiologia, cardiologia, gastroenterologia, medicina do trabalho e do tráfego, oftalmologia e psiquiatria não tem correlação com o uso terapêutico das substâncias em estudo.
A grande quantidade de prescrições realizadas sem a especialidade capacitada para tal é um dado preocupante, visto que os EAA provocam diversos efeitos negativos à saúde. Os efeitos colaterais estão presentes em quase 100% dos usuários, sendo os mais comuns a acne, atrofia testicular, retenção hídrica, alterações do humor e ginecomastia. Além disso, há alterações hormonais, enzimáticas, em células do sistema hematopoiético e no perfil lipídico sanguíneo (LIMA, et al, 2015). Nas mulheres destaca-se o crescimento de pelos, voz grave, diminuição dos seios, além do aumento do clitóris e ausência do ciclo menstrual (FARIA, et al, 2015).
Entre os efeitos colaterais agudos estão as dores de cabeça, retenção de líquidos, irritação gastrointestinal, diarréia, dores de estômago, pele oleosa, icterícia, alterações menstruais e hipertensão. Com a administração de esteroides exógenos, ocorre também a redução da secreção de esteroides endógenos. Nos homens essa supressão endócrina pode levar a hipogonadismo com alterações na função sexual, sendo um estado reversível após a descontinuação do uso. O uso dessas substâncias também está fortemente associado a danos celulares no miocárdio, pois aumentam a resistência vascular periférica e levam à hipertrofia cardíaca juntamente com a diminuição da contratilidade do coração. Os esteroides também possuem efeitos sobre a função tireóidea, com a diminuição de proteínas responsáveis pela manutenção das concentrações séricas de hormônios tireoideanos (LIMA, et al, 2015).
Outros efeitos são a retenção iônica, icterícia e tumores no fígado, aumento das lesões nas articulações (por não estarem aptas ao crescimento exagerado da musculatura), tremores, retenção de líquido, agravamento da apnéia do sono e estrias, oligúria ou disúria, e aumento da próstata. A interrupção abrupta do uso destas substâncias pode levar à depressão por abstinência (FARIA, et al, 2015). Em relação às formas farmacêuticas mais utilizadas, obteve-se os dados mostrados na tabela 4: Para a oxandrolona, a dosagem mais frequentemente utilizada é a de 10mg, havendo uma média de dosagem prescrita de 9,3 para as doses em miligramas e 0,857 para as em porcentagem. Para o estanazolol, a dosagem mais frequente também é a de 10mg, e obteve-se uma média de dose prescrita de 11,777mg.
Segundo Fonini (2006), a meia-vida do estanazolol injetável é de 1 dia, e a de uso oral é de 9 horas. É um esteroide que, em alta dosagem, pode apresentar mais toxicidade ao fígado, principalmente na forma oral. A dosagem indicada é de 16 a 30 mg/dia na forma oral para homens e de 4 a 8 mg/dia para mulheres. A oxandrolona também possui pequena meia-vida de 9 horas, e tem baixa concentração por comprimido (entre 2,5 ou 5mg), sendo que seu uso varia entre 4 a 17 comprimidos por dia para homens e 2 a 4 comprimidos por dia para mulheres (FONINI, 2006). Bolognia (2000) e Gomes (2019) relataram o uso terapêutico de oxandrolona 10mg 2 vezes por dia e estanazolol 2 mg uma vez e duas vezes por dia.
Segundo Markovicz (2019), existem três formas de se utilizar os diferentes esteroides, que podem ser ciclo, pirâmide e stacking. O ciclo se define por qualquer período de utilização da droga, podendo variar de 4 a 18 semanas, sendo feito de tempos em tempos e com intervalo entre eles; a pirâmide se caracteriza pelo início com dosagens pequenas e aumento gradativo até a sua saturação e então redução regressiva até encerrar-se o período; por fim, o stacking se refere ao uso de várias drogas ao mesmo tempo de acordo com a sua toxicidade.
As ordens de manipulação coletadas para a presente pesquisa não trazem a informação da posologia, mas pode-se observar que as doses presentes variam bastante, contendo até altas concentrações de 30mg, e muitas amostras de 20mg no caso da oxandrolona. Segundo Markovicz (2019), para se obter alterações corporais e esportivas, as doses utilizadas geralmente tendem a ser muito maiores do que as recomendadas. Isso pode ter relação com algumas destas altas dosagens encontradas, indicando uso indevido, ou sem fins terapêuticos.
IV.
Considerações Finais
Através dessa pesquisa, os objetivos propostos foram alcançados, obtendo-se um perfil de uso com uma grande quantidade de médicos prescritores não especializados, havendo muitas associações a substâncias que atuam como suplementos dietéticos, indicando uso para fins estéticos/esportivos, com dosagens altas em alguns casos e em seis formas farmacêuticas diferentes.
A grande quantidade de médicos generalistas que prescrevem anabolizantes mostra-se um dado preocupante, devido aos diversos problemas acarretados quando ocorre o uso dessas drogas de forma desnecessária.
O conhecimento sobre anabolizantes e suas ações no organismo é de extrema importância para a prevenção do seu uso indevido, por isso espera-se que profissionais especializados, com conhecimento mais aprofundado acerca do assunto, só realmente utilizem essas substâncias, com tamanho potencial de causar danos, em casos de terapia onde são de fato necessárias, reduzindo a quantidade de prescrições contendo as mesmas.
A informação e o aconselhamento sobre o uso de EAA deve ser difundida, sendo interessante realizar estratégias sobre a difusão do conhecimento a respeito destas drogas para a população, e no caso da rede de farmácias de manipulação, os próprios farmacêuticos podem tomar o papel de informar os pacientes ao realizar a atenção farmacêutica adequada, pois a partir dessa abordagem em pesquisa pode-se obter esclarecimento em relação ao uso destas substâncias, proporcionando melhor orientação ao paciente por parte do farmacêutico.
Determinação Do Perfil De Prescrição De Oxandrolona E Estanazolol Em Farmácias De Manipulação De Vitória Da Conquista No Ano De 2019 Pedro Augusto Cruz Correia α & Matheus Santos Marques σ
Tabela 1 :
1Frequência de prescrições dos medicamentos EAA presentes nas farmácias de manipulação estudadas em 2019 Em relação aos medicamentos escolhidos, a oxandrolona foi muito mais utilizada que o estanazolol, e durante o ano houveram apenas três receitas onde esses medicamentos foram prescritos de forma associada. Em relação ao sexo dos pacientes, 316 (58,3%) pertenciam ao sexo feminino e 226 (41,7%) pertenciam ao sexo masculino. O mecanismo de ação da testosterona e dos androgênios são divididos em duas categorias: efeitos androgênicos, associados à função reprodutora e às características sexuais secundárias masculinas, e efeitos anabólicos, causadores da estimulação do crescimento e a manutenção dos tecidos não reprodutores. Ambos os mecanismos agem em um único receptor, sendo o tecido alvo o fator determinante da resposta hormonal (ANDRADE, 2016). O uso maior de oxandrolona pode se dar devido ao fato de que, segundo Fonini (2006), a oxandrolona causa menos efeitos colaterais pronunciados. Isso também teria relação com a maior presença de pacientes do sexo feminino, já que devido à menor intensidade de efeitos adversos pronunciados essa droga termina sendo um dos EAA mais escolhidos para mulheres. O estudo de Bolognia (2000) corrobora com esse fato, onde foi realizado o tratamento de uma paciente com lipodermatoesclerose, uma patologia dermatológica, com estanazolol e foi percebido que a droga alterou os níveis de enzimas hepáticas, sugerindo possível hepatotoxicidade. Ao se realizar a substituição pela oxandrolona, a paciente apresentou melhora e os indicadores hepáticos voltaram ao normal. Diferentemente da maioria dos EAA utilizados por via oral, a oxandrolona é associada a uma baixa hepatotoxicidade pois passa por um metabolismo hepático limitado (BOLOGNIA, 2000). Entretanto, outro estudo realizado numa paciente que também sofria da mesma doença relatou que o uso de estanazolol no tratamento ocorreu sem a presença de efeitos adversos significativos. No meio do tratamento o uso do estanazolol foi interrompido devido à indisponibilidade da droga no mercado, quando então ocorreu a substituição dessa droga pela oxandrolona, que continuou por um longo período e também sem a presença de efeitos adversos significativos. Mesmo assim, os autores notificaram que caso surgissem indicativos de hepatotoxicidade no tratamento da lipodermatoesclerose, a substituição do estanazolol pela oxandrolona seria uma boa estratégia (GOMES, 2019). Como o número de prescrições de estanazolol foi muito mais baixo do que o de oxandrolona, um possível viés a se considerar seria a falta de abastecimento da droga no mercado para a farmácia, como ocorreu no caso do estudo de GOMES (2019). Em relação às prescrições associadas às especialidades dos médicos, obteve-se os seguintes dados, representados na tabela 2: Tabela 2: Frequência das especialidades médicas prescritoras de EAA nas farmácias de manipulação estudadas durante o ano de 2019Medicamento
Frequência de
prescrições
Porcentagem
Oxandrolona
447
82,5%
Estanazolol
92
17%
Ambos
3
0,6%
Total
542
100%
Fonte: autor
Especialidade médica Frequência de prescrições
Porcentagem
Não registrada
460
84,9%
Anestesiologia
1
0,2%
Angiologia
3
0,6%
Cardiologia Cirurgia geral
Clínica médica Dermatologia
Endocrinologia
Gastroenterologia
Ginecologia e Obstetrícia
Hematologia
Medicina
do
trabalho
Medicina
do
tráfego
Neurocirurgia
Oftalmologia
Ortopedia
Pediatria
Psiquiatria
Radiologia
Urologia
2
9
1
3
6
5
5
1
1
3
4
3
4
6
4
9
12
0,4%
1,7%
0,2%
0,6%
1,1%
0,9%
0,9%
0,2%
0,2%
0,6%
0,7%
0,6%
0,7%
1,1%
0,7%
1,7%
2,2%
Tabela 3 :
3Relação entre especialidades médicas e doenças tratadas com EAAEspecialidade médica
Patologias
Ortopedia, Endocrinologia
Osteoporose
Endocrinologia, Pediatria, Clínica médica
Disfunções de crescimento
Dermatologia, Cirurgia geral
Tratamento de queimaduras graves
Endocrinologia, Urologia, Ginecologia, Clínica médica
Déficit de testosterona
Endocrinologia, Clínica médica
Balanço proteico negativo
Ginecologia
Câncer de mama
Angiologia, Clínica médica
Angiodema hereditário
Hematologia
Anemia aplástica
Ginecologia
Endometriose
Endocrinologia, Clínica médica
Estímulo do crescimento em
puberdade masculina tardia
Urologia, Clínica médica
Insuficiência renal aguda
Neurocirurgia
Mielofibrose
Fonte: autor
10
Year 2022
Global Journal of
Medical Research
Volume XXII Issue II Version I
(
D
D
D
D )
C
© 2022 Global Journals
Determinação Do Perfil De Prescrição De Oxandrolona E Estanazolol Em Farmácias De Manipulação De
Vitória Da Conquista No Ano De 2019
Tabela 4 :
4Frequência de formas farmacêuticas aplicadas aos EAA nas farmácias de manipulação estudadas durante o ano de 2019 injetáveis, sendo que as orais sofrem metabolismo de primeira passagem pelo fígado e têm menor tempo de circulação no sistema, sendo seu excesso eliminado na urina. Já as injetáveis possuem um maior tempo de vida por não sofrer esta ação do fígado (ANDRADE, 2016). Como exemplo, a testosterona natural, quando administrada como medicamento por via oral, torna-se pouco eficaz devido ao rápido metabolismo hepático. Sua meia vida está em Frequência de dosagens prescritas de EAA nas farmácias de manipulação estudadas durante o ano de 2019Forma farmacêutica
Frequência prescrita
Porcentagem
Cápsula (oral)
415
76,6%
Resvin (oral)
21
3,9%
Pentravan (transdérmico)
Versapro (transdérmico)
Sorbitol (oral)
Gotas sublingual (oral)
8
63
22
13
1,5%
11,6%
4,1%
2,4%
Total
542
100%
Fonte: Autor
As
formas
farmacêuticas
de
escolha
englobaram administração por via oral e por via
transdérmica, sendo que a forma mais utilizada foi em
cápsulas por via oral, seguida pela base transdérmica
versapro.
As formas mais conhecidas dos EAA são as
orais e aproximadamente vinte minutos e cerca de 90% de
seus metabólitos são excretados na urina (ANDRADE,
2016).
Dessa forma, segundo Andrade (2016),
oxandrolona e estanazolol são drogas ideais para a
administração por via oral pois são modificadas para
aumentar sua resistência ao metabolismo hepático.
Elas são classificadas como 17 α-derivados devido à
adição de um grupo alquila à posição 17α da
testosterona, o que retarda o seu catabolismo hepático,
proporciona melhor afinidade ao receptor e dificuldade
de ser convertido em estradiol, mas também causa
uma hepatotoxicidade não observada na testosterona
natural. (ANDRADE, 2016; PEREIRA, 2019).
Já a forma de uso por via transdérmica, onde
foram utilizados os veículos versapro e pentravan,
fornece concentrações de testosterona mais estáveis
do que o uso de injeções com ésteres de testosterona
(PEREIRA, 2019) e constitui outra estratégia para reduzir
o metabolismo hepático de primeira passagem.
Em relação às dosagens dos medicamentos,
obteve-se os dados mostrados na tabela 5, sendo que
a
oxandrolona
apresentou
prescrições
com
concentrações em miligramas e porcentagem, e o
estanazolol apenas em miligramas:
Tabela 5: Dosagem da
oxandrolona
em mg
Frequência
de
prescrições
Dosagem da
oxandrolona
em %
Frequência
de
prescrições
Dosagem do
estanazolol
Frequência
de
prescrições
0,5 mg
2
0,5%
3
3 mg
2
2,5 mg
9
0,6%
7
4 mg
2
3 mg
12
0,7%
37
5 mg
15
4 mg
4
0,8%
10
7 mg
7
5 mg
53
0,9%
5
10 mg
48
7 mg
6
1%
3
12 mg
1
7,5 mg
3
1,5%
1
15 mg
15
8 mg
8
20 mg
4
9 mg
2
30 mg
1
10 mg
151
15 mg
13
20 mg
116
30 mg
5
Total
384
66
95
Mecanismos fisiológicos e moleculares dos Esteroides Anabólicos Androgênicos: os efeitos desejáveis. Weidla Fernanda Garcia Andrade, De, 2238-2259-jan-março. 6ANDRADE, Weidla Fernanda Garcia de. Mecanismos fisiológicos e moleculares dos Esteroides Anabólicos Androgênicos: os efeitos desejáveis. Rev. Acta Brasileira do Movimento Humano -Vol.6, n.1, p.56-63 -jan-março, 2016 - ISSN 2238-2259. Disponível em: http://www. periodicos.ulbra.br/index.php/actabrasileira/article/vi ew/2824/2090. Acesso em: 03/10/2019.
Treatment of lipodermatosclerosis with oxandrolone in a patient with stanozolol induced hepatotoxicity. Jean Bolognia, 15/04/2020Revista J A M ACAD DERMATOL. 4300BOLOGNIA, Jean, et al. Treatment of lipodermatosclerosis with oxandrolone in a patient with stanozolol induced hepatotoxicity. Revista J A M ACAD DERMATOL, vol 43, Número 3, p 558-559, 2000. Disponível em: https://www.jaad.org/ article/S0190-9622(00)70261-1/pdf. Acesso em: 15/04/2020
A. esteroides anabolizantes: Culto ao corpo e seus principais efeitos sobre o organismo. F Faria G, S A Cabral, T V Silva, C Miyamoto, Revista Conexão Eletrônica. 1Disponível emFARIA G. F.; CABRAL, S.A. SILVA, T.V. MIYAMOTO, C.A. esteroides anabolizantes: Culto ao corpo e seus principais efeitos sobre o organismo, Revista Conexão Eletrônica -Três Lagoas, MS. V. 12, N. 1, 2015. Disponível em:
| [
-0.09106095880270004,
-0.04420441389083862,
-0.09951289743185043,
-0.035591285675764084,
0.005015314090996981,
-0.0851435512304306,
-0.2146405279636383,
0.19224920868873596,
0.060522183775901794,
0.0592864528298378,
0.1522505283355713,
0.01897875778377056,
0.03558078780770302,
0.0622296705... |
Higher Hospital Frailty Risk Score is associated with increased complications and healthcare resource utilization after endovascular treatment of ruptured intracranial aneurysms Clinical neurology
2022
Andrew B Koo
Aladine A Elsamadicy
Daniela Renedo
Margot Sarkozy
Josiah Sherman
Benjamin C Reeves
John Havlik
Joseph Antonios
Nanthiya Sujijantarat
Ryan Hebert
Ajay Malhotra
Department of Radiology and Biomedical Imaging
Dr Charles Matouk, Neurosurgery
Yale University School of Medicine
New HavenConnecticutUSA
School of Medicine
Yale University
New HavenConnecticutUSA
Charles Matouk
Department of Neurosurgery
Yale University School of Medicine
New Haven, ConnecticutUSA
Higher Hospital Frailty Risk Score is associated with increased complications and healthcare resource utilization after endovascular treatment of ruptured intracranial aneurysms Clinical neurology
J NeuroIntervent Surg
0202210.1136/neurintsurg-2021-0184841 Original research To cite: Koo AB, Elsamadicy AA, Renedo D, et al. J NeuroIntervent Surg Epub ahead of print: [please include Day Month Year].
INTRODUCTION
Ruptured intracranial aneurysms (IAs) account for a majority of non-traumatic subarachnoid hemorrhage (SAH). 1 In recent years the majority of ruptured IAs have been treated using an endovascular approach.
Despite continued advancements in this technology and neurocritical care, aneurysmal SAH remains a devastating disease with a mortality rate in excess of 50% and only 20-33% of survivors making a full recovery. [2][3][4][5][6][7][8][9][10] Given these variable outcomes and the high resource utilization associated with inpatient care, the identification of those most at risk for poor outcomes is desirable.
Frailty is an evolving concept that reflects an individual's increased vulnerability to poor health outcomes. Its utility as a predictive tool is increasingly recognized in general medicine and surgery. Its relevance to neurovascular disease remains poorly studied but of great potential interest. For example, it has been reported that 25-45% of patients with aneurysmal SAH are frail and may be at increased risk for poor outcomes. [11][12][13][14] Operationally, there are various ways to define frailty without widespread consensus on a 'best' methodology. Two commonly used tools are the modified 5-item Frailty Index (mFI-5) and modified 11-item Frailty Index (mFI-11). 15 16 More recently there have been efforts to systematically identify frailty using variables that are routinely collected in national databases. 17 18 One example is the Hospital Frailty Risk Score (HFRS), which is based on a broad set of ICD-10 diagnostic codes over-represented in frailty including codes for volume depletion, chronic pulmonary disease and heart failure. 17 An increasing number of studies have shown the utility of the HFRS to predict mortality and poor health outcomes across a range of medical conditions and surgical procedures including pneumonia, acute myocardial infarction, COVID-19 hospitalizations, and revision total hip and knee arthroplasty. 15 [19][20][21][22] Other recent studies have explored the HFRS as a predictive tool in stroke. 23 To date, the HFRS has not been explored in aneurysmal SAH.
The aim of this study was to use the HFRS to investigate the impact of frailty on complication rates and healthcare resource utilization in patients who underwent endovascular treatment of ruptured IAs.
METHODS
Data source and patient population
The Healthcare Cost and Utilization Project's National Inpatient Sample (NIS) database is a Clinical neurology stratified discharge database representing 20% of all inpatient admissions from community hospitals in the USA. It is the largest all-payer healthcare database in the USA, containing over 7 million hospital admissions (approximately 35 million hospitalizations, weighted) per year. A retrospective study was performed using years 2016-2019 of the NIS for all adult (≥18 years old) patients undergoing endovascular treatment for a ruptured IA. Institutional Review Board (IRB) exemption was obtained prior to initiation of the study.
Within the NIS, the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis and procedural coding system (PCS) was used to identify patients with ruptured aneurysm, as well as their previously diagnosed comorbidities and the surgical interventions they underwent. The ICD-10-CM codes I60.X, I61.X were used (see online supplemental table 1). These identified patients were then crossmatched using ICD-10-PCS codes for endovascular treatment (see online supplemental table 2).
Hospital Frailty Risk Score (HFRS)
Frailty was defined using the HFRS, a validated ICD-10 coding algorithm developed by Gilbert et al 17 and used in multiple studies. [19][20][21][22][23][24][25] The coding algorithm is derived from a cluster of frail individuals with 109 over-represented ICD-10 codes assigned a number of points ranging from 0.1 to 7.1 reflecting the strength of association to the frail cluster. 17 These points are added together for a final frailty risk score. 17 All ICD-10 codes for the admission were entered into the calculation. In addition to presenting frailty as a continuous variable, we then stratified the frailty score into low (HFRS <5), intermediate , and high (HFRS >15), as previously described. 17 A flow chart demonstrating the criteria used to identify the cohorts is shown in online supplemental figure 1.
Data collection
Patient demographics such as age, sex, race, median household income quartile, and insurance provider were all collected from the NIS database. Additional hospital characteristics such as bed size volume, region (Northeast, South, Midwest, and West), and type (rural, urban teaching, and urban non-teaching) were also collected. Elixhauser comorbidities were used to evaluate the incidence of congestive heart failure (CHF), cardiac arrhythmia, valvular disease, hypertension, pulmonary circulation disorders, peripheral vascular disorders, paralysis, other neurological disorders, chronic pulmonary disease, diabetes, hypothyroidism, renal failure, liver disease, peptic ulcer disease excluding bleeding, coagulopathy, obesity, weight loss, fluid and electrolyte disorders, anemia (blood loss or deficiency), and alcohol abuse. In addition, patient admission comorbidities, affective disorders, smoking, and long-term aspirin or anticoagulant use were assessed (online supplemental table 1). Data on aneurysm location were collected including anterior (carotid siphon bifurcation, middle cerebral aneurysm, anterior communication) and posterior (posterior communicating, basilar, vertebral artery) location. Procedural data collected included ventriculoperitoneal shunt, central venous catheter, arterial monitoring, fluoroscopy of cerebral arteries with contrast, vasospasm treatment, videoelectroencephalogram monitoring, and unspecified procedures such as external ventricular drain (online supplemental table 2).
Data regarding postoperative adverse events for each patient were collected by indexing additional diagnoses from the NIS database. Complications included in the analysis were urinary tract infection, post-procedural fever, pressure ulcer, sepsis, cardiogenic shock, cerebral infarction, syndrome of inappropriate antidiuretic hormone secretion, hypo-osmolar hyponatremia, pulmonary embolism, phlebitis, acute deep vein thrombosis, periprocedural stroke, acute myocardial infarction, acute respiratory failure, acute kidney injury, mechanical ventilation, tracheostomy, and gastrostomy (see online supplemental tables 1 and 2). In addition, postoperative outcome measures such as hospital length of stay (LOS), total cost of hospital admission, and discharge disposition were also assessed between the two cohorts. Discharge disposition was classified as routine (home, self-care, home healthcare), non-routine (patient sent to short-term hospital, skilled nursing facility, intermediate care facility), and other (leaving against medical advice, died in hospital, unknown destination). All-payer inpatient cost-to-charge ratios were used to convert total hospital charge to total cost of hospital services.
Statistical analysis
Discharge-level weights provided by the Agency for Healthcare Research and Quality were used to calculate national estimates. Parametric data were expressed as mean±SD and compared using a two-way independent t-test. Non-parametric data were expressed as median (IQR) and compared using the Mann-Whitney U test. Nominal data were compared with the χ 2 test. For our primary hypothesis, weighted univariate and multivariate logistic regressions were fitted with extended postoperative hospital LOS (as defined by LOS greater than the 75th percentile for the entire cohort), increased hospital costs (as defined by total costs greater than the 75th percentile for the entire cohort), and non-routine discharge as the dependent variables. There were no patients with missing information on LOS. Patients with missing total cost variable (n=64) were excluded from this portion of the analysis. Patients with 'other' discharge were also excluded from this portion of the analysis in order to dichotomize routine versus non-routine discharge. Backward stepwise multivariate logistic regression analysis was used to select variables in the final model, using 0.1 as entry and stay criteria. Based on our primary aim and in view of the plausibility for confounding, age and female sex were forced into the models. A p value of <0.05 was deemed to be statistically significant. Statistical analysis was performed using R Studio Version 3.6.2 (RStudio Inc, Boston, Massachusetts, USA).
RESULTS
Patient demographics and hospital characteristics
Adverse events and postoperative outcomes
Overall, the proportion of patients who experienced any adverse event (AE) significantly increased with increasing frailty (low:
DISCUSSION
This retrospective national database study of 33 840 patients who underwent endovascular treatment of a ruptured IA shows that increasing frailty (as measured by HFRS) was associated with increased LOS, rates of hospital AEs, rates of non-routine discharges, and total costs. Further, on multivariate analysis, we found that intermediate and high frailty independently predicted prolonged LOS, increased cost, and non-routine discharge. Frailty is increasingly recognized as a predisposing factor for adverse health outcomes and increased healthcare resource utilization. 26 27 Preliminary efforts have begun to assess the impact of frailty on patients with aneurysmal SAH. In a retrospective analysis of 217 patients who underwent surgical clipping of ruptured IAs, McIntyre et al found that ~26% of patients were frail, defined as mFI score ≥2. 11 Similarly, in a single-institution study of 173 elderly patients (≥60 years) who underwent surgical clipping of a ruptured IA, Yue et al found frailty, as defined by the presence of severe anemia, hypoalbuminemia, or low body mass index, to be common affecting ~45% of their patient cohort. 14 In our study, nearly 75% of patients undergoing endovascular treatment for a ruptured IA were considered to have intermediate (59.3%) or high (17.2%) frailty, as defined by the HFRS.
While there is a paucity of studies directly assessing frailty and outcomes, prior studies have attempted to identify the relationship between frailty and complications after management of ruptured IAs. In the retrospective study of 217 patients with aSAH by McIntyre et al, the authors found on multivariate regression analysis that frail patients were significantly more likely to experience a complication during their hospital stay (OR 2.6). 11 In a retrospective NIS database study of 5353 patients undergoing treatment for ruptured aneurysms between 2012 and 2015, Chotai et al found on multivariate analysis that the odds of experiencing any inpatient complication significantly increased as the neurovascular comorbidity index (NCI) score, a value closely related to frailty, progressed from 1 (OR 1.13) to 4 (OR 1.58) and to 7 (OR 2.05). 28 Similarly, our study of patients undergoing endovascular treatment of ruptured IAs found that, as the severity of frailty increased, the rate of perioperative AEs increased by more than fivefold from the low to the high frailty cohort. Further studies assessing frailty in ruptured IAs are needed to aid in patient risk stratification and patient-centered management strategies. While there is a paucity of studies directly assessing the impact of frailty with hospital LOS and non-routine discharges in patients with ruptured IA, there have been a few that evaluated the impact of comorbidities and other factors closely associated with frailty. In a retrospective NIS database study of 19 034 patients who underwent clipping or coiling of a ruptured or unruptured IA between 2002 and 2006, Hoh et al demonstrated that older age as well as diabetes, coagulopathy, CHF, renal failure, peripheral vascular disorders, and neurological or electrolyte disorders were each independently associated with longer hospitalizations. 29 Of these identified comorbidities, four are included in the commonly used 11-item mFI, 30 three are included in the 5-item mFI, 31 and five are included in the HFRS. 17 However, not all studies have reported results similar to the findings outlined above. For example, in a retrospective observational database study of 203 patients treated for a ruptured IA between 2012 and 2017, Hammer et al found that all analyzed comorbidities including hypertension, diabetes, hypothyroidism, cholesterinemia, and smoking did not have a significant impact on LOS in the intensive care unit. 32 Analogous to the aforementioned studies, our study found that mean hospital LOS more than doubled when comparing low to high HFRS cohorts. Furthermore, on multivariate analysis, we also found 11 Our study also found that rates of non-routine discharge were nearly four times higher in patients with high frailty than in those with low frailty. As prolonged LOS and non-routine discharges have repeatedly been shown to increase healthcare resource utilization and be associated with inferior outcomes in patients undergoing various neurosurgical procedures, further studies should be done to better define the relationship between frailty and LOS following treatment of ruptured IAs. While few studies have examined the impact of frailty on the cost of hospital admission in patients undergoing treatment for IAs, there have been efforts to characterize the effect of frailtyassociated factors on hospital admission cost within this patient population. In the NIS database study of patients treated for a ruptured IA by Chotai et al, the authors found on regression analysis that higher NCI scores were associated with a greater cost of hospital admission. 28 Consistent with these findings, the NIS database study of patients with ruptured or unruptured IA by Hoh et al demonstrated that frailty-associated comorbidities (eg, diabetes, CHF, coagulopathy, electrolyte disorders, neurological disorders, renal failure, and peripheral vascular disorders) and older age were each independently associated with greater hospital costs. 29 Similarly, our study found that the mean cost of hospital admission more than doubled between the low frailty and the high frailty cohort. These data, although limited, demonstrate how frailty may be contributing to the soaring healthcare costs in the USA.
This study has a number of limitations inherent to all administrative databases, including the NIS. First, the analysis is retrospective, potentially limiting the interpretation of our results. The data are also available only by ICD-10-CM codes, which may contain coding and reporting biases. Second, data may be misclassified or incomplete. Third, information regarding preoperative factors such as the size of the IA prior to rupture is unavailable, which may have an unrecognized effect on our results. Also, there may be additional confounding variables present which are unavailable or have not been measured. Finally, given the NIS has information specific to a single inpatient admission, we cannot comment on long-term functional outcomes or the durability of treatment. Despite these limitations, this study uses one of the largest inpatient databases in the USA to provide unique insights into the impact of frailty on postoperative outcomes and healthcare resource utilization for patients undergoing endovascular treatment of ruptured IAs.
CONCLUSION
Our study is the first to use the HFRS to assess the impact of frailty on patients who underwent endovascular treatment for ruptured IAs. We found that greater frailty was associated with increased complications, prolonged hospital LOS, higher total costs, and non-routine discharge. These results highlight the need for further studies that examine the impact of frailty on outcomes following endovascular treatment for a ruptured IA, as it may improve patient care and reduce healthcare resource utilization.
Twitter Ajay Malhotra @AjayMalhotraRad
Contributors ABK: Study conception and design, acquisition of data, analysis and interpretation of data, drafting of the manuscript, critical revision of the manuscript for important intellectual content, statistical analysis. AAE: Study conception and design, analysis and interpretation of data, drafting of the manuscript, critical revision of the manuscript for important intellectual content. DR, MS, JS, BCR, JH, JA, NS: Acquisition of data, drafting of the manuscript, critical revision of the manuscript for important intellectual content. RH: Study conception and design, critical revision of the manuscript for important intellectual content, study supervision. AM: Study conception and design, critical revision of the manuscript for important intellectual content, study supervision. CM: Study conception and design, critical revision of the manuscript for important intellectual content, study supervision, guarantor of the study.
Funding
The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
A total of 33 840 patients were included, of which 7940 (23.5%) were classified as low frailty, 20075 (59.3%) as intermediate frailty, and 5825 (17.2%) as high frailty (table 1). Age increased significantly with increasing HFRS score (low: 54.1 years; intermediate: 57.5 years; high: 58.6 years, p<0.001) (table 1). Healthcare coverage also varied significantly between the frailty cohorts, with the low frailty cohort having a higher percentage of privately insured patients (low: 45.8%; intermediate: 36.7%; high: 35.5%) and patients in the high frailty cohort having a higher percentage of Medicare patients (low: 21.3%; intermediate: 32.8%; high: 35.7%, p<0.001) (table 1). While treating hospital region varied significantly between cohorts (p<0.001), race, household income quartile, weekend admission rate, and hospital bed size and type were all similar among the frailty cohorts (table 1). Patient comorbidities, aneurysm locations and other surgical/ intensive care procedures The average HFRS score for each cohort was 2.7±1.6, 9.7±2.8, 18.7±3.0 for the low, intermediate, and high frailty cohorts, respectively (table 2). On comparison of the admission comorbidities and clinical presentation between frailty cohorts, seizure (p<0.001), neurological deficit associated with SAH (p=0.002), coma (p<0.001), aphasia (p<0.001), dysphagia (p<0.001), and hypertensive chronic kidney disease (p<0.001) were notably all significantly increased with increasing frailty score (table 2). IA location also varied across the frailty cohorts, with the greatest proportion of IAs located in the anterior communicating artery (low: 26.9%; intermediate: 27.4%; high: 27.8%, p<0.001) (table 2). In general, significantly more procedures were done as the frailty score increased across the cohorts (table 2). For example, the proportion of patients who underwent external ventricular drainage (low: 25.3%; intermediate: 51.8%; high: 60.3%, p<0.001) and subsequent ventriculoperitoneal shunt placement (low: 3.6%; intermediate: 10.6%; high: 15.8%, p<0.001) increased along with the HFRS score (table 2).
Table 1
1Patient demographics and hospital characteristicsVariables
Low
(n=7940)
Intermediate
(n=20 075)
High
(n=5825) P value
Age (years)
Mean±SD
54.1±13.6 57.5±14.2
58.6±13.7 <0.001
Female (%)
63.0
67.2
69.9
<0.001
Race (%)
0.386
White
56.8
57.9
55.1
Black
18.9
17.4
17.6
Hispanic
13.7
13.8
16.1
Other
10.5
10.9
11.2
Income quartile (%)
0.158
0-25th
30.5
29.7
30.8
26-50th
26.7
24.1
23.7
51-75th
22.3
25.7
25.2
76-100th
20.4
20.5
20.3
Admitted during weekend (%)
24.2
28.3
28.7
0.005
Healthcare coverage (%)
<0.001
Medicare
21.3
32.8
35.7
Medicaid
18.8
20.0
19.6
Private insurance
45.8
36.7
35.5
Other
14.1
10.5
9.2
Hospital demographics
Hospital region (%)
<0.001
Northeast
17.8
19.4
15.1
Midwest
17.5
18.3
22.9
South
42.8
40.0
36.7
West
21.9
22.3
25.3
Hospital bed size (%)
0.626
Small
5.0
4.9
5.4
Medium
18.1
16.7
18.3
Large
77.0
78.4
76.3
Hospital type (%)
0.618
Rural
0.3
0.1
0.3
Urban non-teaching
6.4
6.3
5.9
Urban teaching
93.3
93.5
93.8
Table 2
2Patient comorbidities, aneurysm location, and surgical/
intensive care procedures
Variables
Low
(n=7940)
Intermediate
(n=20 075)
High
(n=5825)
P value
Frailty risk score
Mean±SD
2.7±1.6
9.7±2.8
18.7±3.0
<0.001
Comorbidities (%)
Seizure
1.3
8.4
16.2
<0.001
Neurological
deficit associated
with subarachnoid
hemorrhage
0.1
0.6
1.0
0.002
Coma
0.9
5.5
7.9
<0.001
Aphasia
1.8
9.4
21.8
<0.001
Dysphagia
2.6
15.7
34.9
<0.001
Cranial nerve
palsy
3.6
4.0
4.5
0.527
Diplopia
2.1
2.3
1.8
0.581
Hypertensive
chronic kidney
disease
0.4
3.6
6.2
<0.001
Personal history of
transient ischemic
attack
3.4
3.9
3.4
0.633
Headache
4.8
3.2
3.7
0.010
Affective disorder 12.8
16.3
17.1
0.002
Smoking
24.8
23.5
20.3
0.018
Congestive heart
failure
3.1
8.1
11.1
<0.001
Cardiac
arrhythmias
12.7
23.0
30.9
<0.001
Valvular disease
1.3
3.4
3.9
<0.001
Pulmonary
circulation
disorders
1.1
3.3
4.3
<0.001
Peripheral
vascular disorders
4.7
5.9
6.1
0.156
Hypertension,
combined
63.5
71.2
73.6
<0.001
Paralysis
0.9
15.6
53.6
<0.001
Other neurological
disorders
14.2
43.9
64.0
<0.001
Chronic
pulmonary
disease
10.1
14.4
13.2
<0.001
Diabetes,
uncomplicated
7.5
6.8
6.0
0.321
Renal failure
1.0
5.0
8.5
<0.001
Hypothyroidism
6.4
8.1
7.6
0.076
Liver disease
1.8
3.5
3.0
0.003
Peptic ulcer
disease
0.2
0.3
1.4
0.017
Coagulopathy
4.3
7.6
8.3
<0.001
Obesity
12.5
14.6
12.6
0.074
Weight loss
2.7
9.4
16.3
<0.001
Continued
Table 2 Continued
2
Table 3
3Adverse events and postoperative outcomesVariables
Low
(n=7940)
Intermediate
(n=20 075)
High
(n=5825)
P value
Adverse events (%)
Vasospasm
13.0
37.9
55.3
<0.001
Hydrocephalus
34.1
60.5
69.4
<0.001
Urinary tract infection
1.3
16.4
46.5
<0.001
Post-procedural fever
0.5
0.2
0.5
0.108
Pressure ulcer
0.0
1.4
4.0
<0.001
Sepsis
0.4
6.6
13.8
<0.001
Cardiogenic shock
0.3
1.4
1.5
0.002
Cerebral infarction
2.2
11.5
22.4
<0.001
Syndrome of inappropriate antidiuretic hormone secretion
3.5
4.2
4.1
0.421
Hypo-osmolar hyponatremia
15.9
30.5
33.4
<0.001
Pulmonary embolism
0.4
1.8
2.6
<0.001
Phlebitis
0.3
0.8
1.1
0.045
Acute deep vein thrombosis
2.0
7.8
13.6
<0.001
Periprocedural stroke
0.4
1.6
1.7
0.001
Acute myocardial infarction
1.3
3.2
3.8
<0.001
Acute respiratory failure
14.2
47.3
66.4
<0.001
Acute kidney injury
1.5
10.2
17.9
<0.001
Mechanical ventilation
16.2
47.5
66.1
<0.001
Tracheostomy
2.1
11.4
22.3
<0.001
Gastrostomy
3.0
14.1
31.0
<0.001
Any adverse event
59.9
92.4
99.2
<0.001
Number of adverse events
<0.001
0
48.7
14.4
3.3
1
27.5
18.0
9.2
>1
23.8
67.6
87.6
Mortality (%)
6.4
15.3
10.8
<0.001
Length of stay (days)
Mean±SD
11.7±8.2
18.7±14.1
26.6±20.1
<0.001
Median (IQR)
11 (7-15)
16 (11-23)
22 (16-31)
<0.001
Total cost of admission ($)
Mean±SD
62 888±37 757
99 670±63 446
134 937±80 331
<0.001
Median (IQR)
55 247 (39 050-75 934)
83 358 (56 981-122 835)
112 881 (82 426-164 897)
<0.001
Disposition (%)
<0.001
Routine
75.1
39.8
19.6
Non-routine
17.3
44.4
69.4
Other
7.6
15.7
11.1
Table 4
4Logistic multivariate regression analyses on prolonged LOS, increased cost, and non-routine discharge disposition LOS, length of stay.Variables
Prolonged LOS
Increased cost
Non-routine discharge
Frailty risk category
OR (95% CI)
P value
OR (95% CI)
P value
OR (95% CI)
P value
Low
Reference
Intermediate
2.38 (1.84 to 3.09)
<0.001
2.15 (1.66 to 2.77)
<0.001
2.13 (1.79 to 2.55)
<0.001
High
4.49 (3.36 to 6.00)
<0.001
3.62 (2.71 to 4.83)
<0.001
4.17 (3.26 to 5.33)
<0.001
Age
0.99 (0.99 to 0.99)
0.038
0.99 (0.98 to 0.99)
0.003
1.04 (1.03 to 1.05)
<0.001
Female sex
0.91 (0.79 to 1.04)
0.172
0.86 (0.74 to 0.99)
0.035
0.76 (0.65 to 0.88)
<0.001
Aphasia
1.63 (1.32 to 2.01)
<0.001
1.35 (1.09 to 1.66)
0.005
1.68 (1.35 to 2.11)
<0.001
Dysphagia
3.00 (2.55 to 3.52)
<0.001
2.04 (1.72 to 2.41)
<0.001
3.95 (3.20 to 4.87)
<0.001
Headache
0.72 (0.49 to 1.07)
0.101
0.51 (0.32 to 0.83)
0.006
0.50 (0.34 to 0.73)
<0.001
Aneurysm location
Anterior
Reference
Posterior
1.02 (0.87 to 1.20)
0.824
1.05 (0.89 to 1.23)
0.587
0.85 (0.72 to 0.99)
0.041
Unspecified
1.00 (0.85 to 1.17)
0.954
1.10 (0.93 to 1.30)
0.254
1.30 (1.11 to 1.53)
<0.001
Number of adverse events
0
Reference
1
4.20 (2.61 to 6.76)
<0.001
2.81 (1.87 to 4.24)
<0.001
1.89 (1.52 to 2.36)
<0.001
>1
19.75 (12.73 to 30.65)
<0.001
14.40 (9.99 to 20.73)
<0.001
6.74 (5.55 to 8.18)
<0.001
Clinical neurologyPatient consent for publication Not applicable.Provenance and peer review Not commissioned; externally peer reviewed.Data availability statement All data relevant to the study are included in the article or uploaded as supplemental information. Not applicable.Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.This article is made freely available for personal use in accordance with BMJ's website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.ORCID iDsAjay Malhotra http://orcid.org/0000-0001-9223-6640 Charles Matouk http://orcid.org/0000-0003-3234-9541
. 10.1212/CON.0000000000000679Muehlschlegel S. Subarachnoid hemorrhage. Continuum. 24Muehlschlegel S. Subarachnoid hemorrhage. Continuum 2018;24:1623-57.
Guidelines for the management of spontaneous intracerebral hemorrhage in adults: 2007 update: a guideline from the American Heart Association/American Stroke Association Stroke Council, High Blood Pressure Research Council, and the Quality of Care and Outcomes in Research Interdisciplinary Working Group. J Broderick, S Connolly, E Feldmann, 10.1161/STROKEAHA.107.183689Stroke. 38Broderick J, Connolly S, Feldmann E, et al. Guidelines for the management of spontaneous intracerebral hemorrhage in adults: 2007 update: a guideline from the American Heart Association/American Stroke Association Stroke Council, High Blood Pressure Research Council, and the Quality of Care and Outcomes in Research Interdisciplinary Working Group. Stroke 2007;38:2001-23.
Intracerebral hemorrhage more than twice as common as subarachnoid hemorrhage. J P Broderick, T Brott, T Tomsick, 10.3171/jns.1993.78.2.0188J Neurosurg. 78Broderick JP, Brott T, Tomsick T, et al. Intracerebral hemorrhage more than twice as common as subarachnoid hemorrhage. J Neurosurg 1993;78:188-91.
Unruptured intracranial aneurysms: epidemiology, natural history, management options, and familial screening. R D Brown, J P Broderick, 10.1016/S1474-4422(14)70015-8Lancet Neurol. 13Brown RD, Broderick JP. Unruptured intracranial aneurysms: epidemiology, natural history, management options, and familial screening. Lancet Neurol 2014;13:393-404.
Case-fatality rates and functional outcome after subarachnoid hemorrhage: a systematic review. J W Hop, G J Rinkel, A Algra, 10.1161/01.STR.28.3.660Stroke. 28Hop JW, Rinkel GJ, Algra A, et al. Case-fatality rates and functional outcome after subarachnoid hemorrhage: a systematic review. Stroke 1997;28:660-4.
Targeting TLR4-dependent inflammation in posthemorrhagic brain injury. J K Karimy, B C Reeves, K T Kahle, 10.1080/14728222.2020.1752182Expert Opin Ther Targets. 24Karimy JK, Reeves BC, Kahle KT. Targeting TLR4-dependent inflammation in post- hemorrhagic brain injury. Expert Opin Ther Targets 2020;24:525-33.
Subarachnoid hemorrhage: updates in diagnosis and management. B Long, A Koyfman, M S Runyon, 10.1016/j.emc.2017.07.001Emerg Med Clin North Am. 35Long B, Koyfman A, Runyon MS. Subarachnoid hemorrhage: updates in diagnosis and management. Emerg Med Clin North Am 2017;35:803-24.
Epidemiology of subarachnoid hemorrhage in Finland from 1983 to 1985. C Sarti, J Tuomilehto, V Salomaa, 10.1161/01.STR.22.7.848Stroke. 22Sarti C, Tuomilehto J, Salomaa V, et al. Epidemiology of subarachnoid hemorrhage in Finland from 1983 to 1985. Stroke 1991;22:848-53.
Prevalence of unruptured intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time period: a systematic review and meta-analysis. M H Vlak, A Algra, R Brandenburg, 10.1016/S1474-4422(11)70109-0Lancet Neurol. 10Vlak MH, Algra A, Brandenburg R, et al. Prevalence of unruptured intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time period: a systematic review and meta-analysis. Lancet Neurol 2011;10:626-36.
Management of unruptured intracranial aneurysms. L N Williams, R D Brown, 10.1212/CPJ.0b013e31828d9f6bNeurol Clin Pract. 3Williams LN, Brown RD. Management of unruptured intracranial aneurysms. Neurol Clin Pract 2013;3:99-108.
Age predicts outcomes better than frailty following aneurysmal subarachnoid hemorrhage: a retrospective cohort analysis. M K Mcintyre, C Gandhi, A Long, 10.1016/j.clineuro.2019.105558Clin Neurol Neurosurg. 187105558McIntyre MK, Gandhi C, Long A, et al. Age predicts outcomes better than frailty following aneurysmal subarachnoid hemorrhage: a retrospective cohort analysis. Clin Neurol Neurosurg 2019;187:105558.
Impact of frailty on outcomes in surgical patients: a systematic review and meta-analysis. A C Panayi, A R Orkaby, D Sakthivel, 10.1016/j.amjsurg.2018.11.020Am J Surg. 218Panayi AC, Orkaby AR, Sakthivel D, et al. Impact of frailty on outcomes in surgical patients: a systematic review and meta-analysis. Am J Surg 2019;218:393-400.
Frailty and the prediction of negative health outcomes: a meta-analysis. S Vermeiren, R Vella-Azzopardi, D Beckwée, 10.1016/j.jamda.2016.09.010J Am Med Dir Assoc. 17Vermeiren S, Vella-Azzopardi R, Beckwée D, et al. Frailty and the prediction of negative health outcomes: a meta-analysis. J Am Med Dir Assoc 2016;17:1163. e1-17.
A prognostic model for early post-treatment outcome of elderly patients with aneurysmal subarachnoid hemorrhage. Q Yue, Y Liu, B Leng, 10.1016/j.wneu.2016.08.020World Neurosurg. 95Yue Q, Liu Y, Leng B, et al. A prognostic model for early post-treatment outcome of elderly patients with aneurysmal subarachnoid hemorrhage. World Neurosurg 2016;95:253-61.
External validation of the Hospital Frailty Risk Score and comparison with the Hospital-patient One-year Mortality Risk Score to predict outcomes in elderly hospitalised patients: a retrospective cohort study. F Mcalister, C Van Walraven, 10.1136/bmjqs-2018-008661BMJ Qual Saf. 28McAlister F, van Walraven C. External validation of the Hospital Frailty Risk Score and comparison with the Hospital-patient One-year Mortality Risk Score to predict outcomes in elderly hospitalised patients: a retrospective cohort study. BMJ Qual Saf 2019;28:284-8.
Validation of hospital frailty risk score to predict hospital use in older people: evidence from the Australian Longitudinal Study on Women's Health. D S Shebeshi, X Dolja-Gore, J Byles, 10.1016/j.archger.2020.104282Arch Gerontol Geriatr. 92104282Shebeshi DS, Dolja-Gore X, Byles J. Validation of hospital frailty risk score to predict hospital use in older people: evidence from the Australian Longitudinal Study on Women's Health. Arch Gerontol Geriatr 2021;92:104282.
Development and validation of a Hospital Frailty Risk Score focusing on older people in acute care settings using electronic hospital records: an observational study. T Gilbert, J Neuburger, J Kraindler, 10.1016/S0140-6736(18)30668-8Lancet. 391Gilbert T, Neuburger J, Kraindler J, et al. Development and validation of a Hospital Frailty Risk Score focusing on older people in acute care settings using electronic hospital records: an observational study. Lancet 2018;391:1775-82.
Operationalization of frailty using eight commonly used scales and comparison of their ability to predict all-cause mortality. O Theou, T D Brothers, A Mitnitski, 10.1111/jgs.12420J Am Geriatr Soc. 61Theou O, Brothers TD, Mitnitski A, et al. Operationalization of frailty using eight commonly used scales and comparison of their ability to predict all-cause mortality. J Am Geriatr Soc 2013;61:1537-51.
Validation of the hospital frailty risk score in older surgical patients: a population-based retrospective cohort study. G M Gunnarsdottir, S Helgadottir, S G Einarsson, 10.1111/aas.13837Acta Anaesthesiol Scand. 65Gunnarsdottir GM, Helgadottir S, Einarsson SG, et al. Validation of the hospital frailty risk score in older surgical patients: a population-based retrospective cohort study. Acta Anaesthesiol Scand 2021;65:1033-42.
The Hospital Frailty Risk Score and its association with in-hospital mortality, cost, length of stay and discharge location in patients with heart failure. C S Kwok, S Zieroth, Van Spall, Hgc , 10.1016/j.ijcard.2019.09.064Int J Cardiol. 300Kwok CS, Zieroth S, Van Spall HGC, et al. The Hospital Frailty Risk Score and its association with in-hospital mortality, cost, length of stay and discharge location in patients with heart failure. Int J Cardiol 2020;300:184-90.
Hospital Frailty Risk Score predicts adverse events in primary total hip and knee arthroplasty. M Meyer, L Parik, F Leiß, 10.1016/j.arth.2020.06.087J Arthroplasty. 35Meyer M, Parik L, Leiß F, et al. Hospital Frailty Risk Score predicts adverse events in primary total hip and knee arthroplasty. J Arthroplasty 2020;35:3498-504.
Clinical Frailty Score vs Hospital Frailty Risk Score for predicting mortality and other adverse outcome in hospitalised patients with COVID-19: Spanish case series. J-M Ramos-Rincon, O Moreno-Perez, H Pinargote-Celorio, 10.1111/ijcp.14599Int J Clin Pract. 7514599Ramos-Rincon J-M, Moreno-Perez O, Pinargote-Celorio H, et al. Clinical Frailty Score vs Hospital Frailty Risk Score for predicting mortality and other adverse outcome in hospitalised patients with COVID-19: Spanish case series. Int J Clin Pract 2021;75:e14599.
Utility of the hospital frailty risk score derived from administrative data and the association with stroke outcomes. M F Kilkenny, H T Phan, R I Lindley, 10.1161/STROKEAHA.120.033648Stroke. 52Kilkenny MF, Phan HT, Lindley RI, et al. Utility of the hospital frailty risk score derived from administrative data and the association with stroke outcomes. Stroke 2021;52:2874-81.
Evaluating the impact of frailty on periprocedural adverse events and mortality among patients with Gi bleeding. C J Acosta, D Goldberg, S Amin, 10.1016/j.gie.2021.03.021Gastrointest Endosc. 94Acosta CJ, Goldberg D, Amin S. Evaluating the impact of frailty on periprocedural adverse events and mortality among patients with Gi bleeding. Gastrointest Endosc 2021;94:517-25.
Predicting outcomes in older patients undergoing vascular surgery using the hospital frailty risk score. S J Aitken, S Lujic, D A Randall, 10.1002/bjs.12043doi:10.1002/ bjs.12043Br J Surg. 9Aitken SJ, Lujic S, Randall DA, et al. Predicting outcomes in older patients undergoing vascular surgery using the hospital frailty risk score. Br J Surg 2020. doi:10.1002/ bjs.12043. [Epub ahead of print: 09 Oct 2020].
Incidence of spinal cord injury worldwide: a systematic review. A Clegg, J Young, S Iliffe, 10.1159/000279335Neuroepidemiology. 381Lancet. discussion 92Clegg A, Young J, Iliffe S, et al. Frailty in elderly people. Lancet 2013;381:752-62. 27 van den Berg MEL, Castellote JM, Mahillo-Fernandez I, et al. Incidence of spinal cord injury worldwide: a systematic review. Neuroepidemiology 2010;34:184-92. discussion 92.
Impact of neurovascular comorbidities and complications on outcomes after procedural management of intracranial aneurysm: Part 2, ruptured intracranial aneurysm. S Chotai, P D Patel, C Liles, 10.1016/j.wneu.2020.10.091World Neurosurg. 146Chotai S, Patel PD, Liles C, et al. Impact of neurovascular comorbidities and complications on outcomes after procedural management of intracranial aneurysm: Part 2, ruptured intracranial aneurysm. World Neurosurg 2021;146:e270-312.
Length of stay and total hospital charges of clipping versus coiling for ruptured and unruptured adult cerebral aneurysms in the nationwide inpatient sample database. B L Hoh, Y-Y Chi, M F Lawson, 10.1161/STROKEAHA.109.569269Stroke. 41Hoh BL, Chi Y-Y, Lawson MF, et al. Length of stay and total hospital charges of clipping versus coiling for ruptured and unruptured adult cerebral aneurysms in the nationwide inpatient sample database 2002 to 2006. Stroke 2010;41:337-42.
The 5 and 11 factor modified frailty indices are equally effective at outcome prediction using TQIP. B M Tracy, M A Adams, M L Schenker, 10.1016/j.jss.2020.05.090J Surg Res. 255Tracy BM, Adams MA, Schenker ML, et al. The 5 and 11 factor modified frailty indices are equally effective at outcome prediction using TQIP. J Surg Res 2020;255:456-62.
The modified 5-Item Frailty Index: a concise and useful tool for assessing the impact of frailty on postoperative morbidity following elective posterior lumbar fusions. D J Weaver, A T Malik, N Jain, 10.1016/j.wneu.2018.12.168doi:10.1016/j. wneu.2018.12.168World Neurosurg. 11Epub ahead of printWeaver DJ, Malik AT, Jain N, et al. The modified 5-Item Frailty Index: a concise and useful tool for assessing the impact of frailty on postoperative morbidity following elective posterior lumbar fusions. World Neurosurg 2019. doi:10.1016/j. wneu.2018.12.168. [Epub ahead of print: 11 Jan 2019].
Impact of complications and comorbidities on the intensive care length of stay after aneurysmal subarachnoid haemorrhage. A Hammer, G Ranaie, F Erbguth, 10.1038/s41598-020-63298-9Sci Rep. 106228Hammer A, Ranaie G, Erbguth F, et al. Impact of complications and comorbidities on the intensive care length of stay after aneurysmal subarachnoid haemorrhage. Sci Rep 2020;10:6228.
| [
-0.05390032380819321,
-0.03570463880896568,
-0.08450579643249512,
0.07042333483695984,
-0.02218751050531864,
0.09708601236343384,
-0.19638881087303162,
0.23078393936157227,
0.0388348363339901,
-0.07079187035560608,
-0.03023252636194229,
-0.04252639412879944,
0.121322862803936,
0.0987712293... |
Toward Optimal Coupon Allocation in Social Networks: An Approximate Submodular Optimization Approach
2 Feb 2018
Shaojie Tang shaojie.tang@utdallas.edu
Naveen Jindal School of Management
University of Texas at Dallas
Toward Optimal Coupon Allocation in Social Networks: An Approximate Submodular Optimization Approach
2 Feb 2018D0EFE0F72F29D9FEF1E9DB3493EA1B1CarXiv:1802.00526v1[cs.SI]
CMO Council reports that 71% of internet users in the U.S. were influenced by coupons and discounts when making their purchase decisions.It has also been shown that offering coupons to a small fraction of users (called seed users) may affect the purchase decisions of many other users in a social network.This motivates us to study the optimal coupon allocation problem, and our objective is to allocate coupons to a set of users so as to maximize the expected cascade.Different from existing studies on influence maximizaton (IM), our framework allows a general utility function and a more complex set of constraints.In particular, we formulate our problem as an approximate submodular maximization problem subject to matroid and knapsack constraints.Existing techniques relying on the submodularity of the utility function, such as greedy algorithm, can not work directly on a non-submodular function.We use to measure the difference between our function and its closest submodular function and propose a novel approximate algorithm with approximation ratio β( ) with lim →0 β( ) = 1 − 1/e.This is the best approximation guarantee for approximate submodular maximization subject to a partition matroid and knapsack constraints, our results apply to a broad range of optimization problems that can be formulated as an approximate submodular maximization problem.
Introduction
It has been reported that one of the most effective ways of running promotions on social media is the use of coupon campaigns on the largest social media site such as Facebook and Twitter.Different from conventional online advertising, the offer of a coupon on social network could trigger a large amount of likes and shares on your product and build brand awareness rapidly.This motivates us to study the coupon allocation problem, e.g., allocating coupons to a few users so as to maximize the expected cascade.More specifically, we assume that the company would like to promote a product through offering coupons with different values to a subset of users.Whether a user would accept the coupon and further become the seed node is probabilistic, which depends on the value of the coupon.Our goal is to select a set of users and allocate one proper coupon to each of them, such that the expected cascade is maximized.
We notice that our problem is closely related to influence maximization problem (IM).Although IM has been extensively studied in the literature [Kempe et al., 2003;Chen et al., 2013;Leskovec et al., 2007;Cohen et al., 2014;Chalermsook et al., 2015], most of existing studies assume a "budgeted, deterministic and submodular" setting, where there is a predefined budget for selecting seed nodes, any node is guaranteed to be activated as a seed node once it is selected, and the utility function is assumed to be submodular in terms of seed nodes.However, these assumptions may not always hold in reality.Firstly, the probability that a user is activated as a seed node depends on many factors, including the actual amount of rewards received from the company [Yang et al., 2016].Secondly, the utility function may not always satisfy the submodular property, e.g., some user can only be influenced if majority of her friends are activated [Kuhnle et al., 2017].
In this paper, we study the coupon allocation problem that allows a general utility function.In particular, we assume an -approximate submodular function where measures the distance between a given function and its closest submodular function (a detailed definition can be found in Section 3.1).We formulate the coupon allocation problem as an approximate submodular maximization problem subject to a partition matroid and knapsack constraints.Existing techniques relying on the submodularity of the utility function, such as greedy algorithm, can not work directly on a non-submodular function.We propose a novel approximate algorithm with approximation ratio β( ) with lim →0 β( ) = 1 − 1/e.This is, to the best of our knowledge, the strongest theoretical result available for approximate submodular maximization problem subject to a partition matroid and knapsack constraints.Although we restrict our attention to coupon allocation in this paper, our results apply to a broad range of non-submodular maximization problems.
The contributions of this paper can be summarized as follows: (1) We are the first to study the coupon allocation problem that allows a general utility function.Our objective is to determine the best coupon allocation so as to maximize
Notation Meaning
S the ground set that contains all u-c pairs S v all u-c pairs whose user is v f (S) the expected cascade of S y a decision matrix F (y)
the multilinear extension of f f + (y)
the concave extension of f g a submodular function used to bound f a ⊕ b the coordinate wise maximum of a and b
F x ([vd]) F (x ⊕ 1 vd ) − F (x)
the expected cascade subject to (partition) matroid and knapsack constraints.(2) We develop an efficient algorithm with approximation ratio that depends on .When = 0 (the utility function is submodular), our result converges to 1 − 1/e which is the best possible for submodular maximization subject to matroid constraints.This research contributes fundamentally to the development of approximate solutions for any problems that fall into the family of approximate submodular maximization.
Some important notations are listed in Table 1.
Related Work
IM has been extensively studied in the literature [Kempe et al., 2003;Chen et al., 2013;Leskovec et al., 2007;Cohen et al., 2014;Chalermsook et al., 2015], their objective is to find a set of influential customers so as to maximize the expected cascade.However, our work differ from all existing studies in several major aspects.Traditional IM assumes any node is guaranteed to be activated once it is selected, we relax this assumption by allowing users to response differently to different coupon values.Recently, [Yang et al., 2016] study discount allocation problem in social networks.However, they assume a submodular utility function and continuous setting of discount value, our model allows a general utility function.We formulate our problem as an approximate submodular maximization problem subject to matroid and knapsack constraints.Existing approaches, such as greedy algorithm [Horel and Singer, 2016], can not apply directly to matroid and knapsack constraints.We propose a novel algorithm that provides the first bounded approximate solutions to this problem.It was worth noting that our approximation ratio converges to 1 − 1/e when = 0.This is the best theoretical result available for approximate submodular maximization subject to a partition matroid constraint.
Preliminaries
Submodular Function and Its Continuous Extensions
A submodular function is a set function h : 2 Ω → R, where 2 Ω denotes the power set of Ω, which satisfies a natural "diminishing returns" property: the marginal gain from adding an element to a set X is at least as high as the marginal gain from adding the same element to a superset of X. Formally, a submodular function satisfies the follow property: For every
X, Y ⊆ Ω with X ⊆ Y and every x ∈ Ω\Y , we have that h(X ∪ {x}) − h(X) ≥ h(Y ∪ {x}) − h(Y ) We say a sub- modular function f is monotone if h(X) ≤ h(Y ) whenever X ⊆ Y .
Continuous Extensions
Consider any vector x = {x 1 , x 2 , . . ., x n } such that each 0 ≤ x i ≤ 1.The multilinear extension of h is defined as H(x) = X⊆Ω h(X) i∈X x i i / ∈X (1 − x i ), and the concave extension of h is defined as
h + (x) = max{ X⊆Ω α X f (X)|α X ≥ 0, X⊆Ω α X ≤ 1, X α X 1 X ≤ x}.
-approximate Submodular Function An -approximate submodular function is a set function f : 2 Ω → R that satisfies the following condition: there exists a submodular function h such that for any X ⊆ Ω, we have
(1 − )h(X) ≤ f (X) ≤ (1 + )h(X).
Coupon Adoption and Propagation Model
Assume there are n users V = {1, 2, . . ., n} and m types of coupons D = {1, 2, . . ., m}.For simplicity of presentation, we will directly use d to denote the coupon value of d.Given the set of users V and possible coupon values D, define S V × D as the solution space, adding a user-coupon (u-c) pair [vd] ∈ S to our solution translates to offering coupon d ∈ D to user v ∈ V.When any coupon d ∈ D is allocated to any user v ∈ V, we assume that with probability p v (d) ∈ (0, 1], v adopts d and becomes a seed node, thus incurs a cost d.We further assume that coupons cannot be combined, if a user received multiple coupons, her adoption decision only depends on the coupon with the highest value.
After a set of users become seed nodes, they start to influence other users.Assume U is the seed set, the expected cascade of U , which is the expected number of influenced users given seed set U , is denoted as γ(U ).In this work, we assume that γ(U ) is a -approximate submodular function: there exists a submodular function q such that for any U ∈ V, we have (1 − )q(U ) ≤ γ(U ) ≤ (1 + )q(U ).Our propagation model subsumes many classic propagation models, including Independent Cascade Model and Linear Threshold Model [Kempe et al., 2003] as special cases, as the propagation functions defined in their models are submodular and monotone, i.e., = 0.
Problem Statement
Our objective is to identify the best coupon allocation policy, not necessarily deterministic, to maximize the expected cascade.Given a coupon allocation S ⊆ S, we use d S (v) to denote the largest coupon value allocated to user v under S, then the probability that a subset of users U ⊆ V successfully become the seed set is
Pr(U ; S) = u∈U p u (d S (u)) v∈V\U (1 − p v (d S (v)))
As introduced earlier, we use γ(U ) to denote the expected cascade under seed set U , then the expected cascade under allocation S is f (S) = U ∈2 V Pr(U ; S)γ(U ).
We first prove that f is also -approximate submodular.
Lemma 1.If γ is -approximate submodular, f is alsoapproximate submodular: there exists a submodular function g such that ∀S ∈ S : (1 − )g(S) ≤ f (S) ≤ (1 + )g(S).
Proof.Based on a similar proof provided in [Soma and Yoshida, 2015], we can show that if q(U ) is submodular of U , U ∈2 V Pr(U ; S)q(U ) is submodular of S. Because
(1 − )q(U ) ≤ γ(U ) ≤ (1 + )q(U ) we have (1 − ) U ∈2 V Pr(U ; S)q(U ) ≤ f (S) ≤ (1 + ) U ∈2 V Pr(U ; S)q(U ).
We finish the proof by defining g(S) = U ∈2 V Pr(U ; S)q(U ).
The expected cost of a coupon allocation S is
c(S) = U ∈2 V Pr(U ; S) u∈U d S (u)
Coupon Allocation Policy We denote by Θ = {θ S : S ⊆ S} a coupon allocation policy, where θ S is the probability that S is adopted.Then the expected cascade under
Θ is f (Θ) = S∈S θ S f (S). The expected cost of Θ is c(Θ) = S∈S θ S c(S).
Definition 1 (Feasible Coupon Allocation Policy).We say a policy Θ is feasible if and only the following conditions are satisfied:
• (Attention Constraint) For every user v ∈ V, we denote
S v = {[vd] : d ∈ D}. ∀θ S > 0, ∀v : |S v ∩ S| ≤ 1, e.g.
, every user receives at most one coupon.• (Budget Constraint) S∈S θ S c(S) ≤ B, e.g., the expected value of the coupons redeemed is at most B.
Our objective is to identify a feasible coupon allocation policy that maximizes the expected cascade.We present the formal definition of our problem in P.A. P.A maxΘ S∈S θSf (S) subject to:
∀θS > 0, ∀v ∈ V : |Sv ∩ S| ≤ 1 S∈S θSc(S) ≤ B S∈S θS = 1
We extend our model in Section 6 by incorporating one more constraint, e.g., a feasible policy can not allocate coupons to more than K users.This constraint captures the fact that the company often has limited budgeted on coupon producing and distribution.
An Approximate Solution
We first introduce a new problem P.B as follows.
P.B: Maximize f + (y) subject to:
∀v ∈ V : d∈D y vd ≤ 1 (C1) [vd]∈S y vd pv(d)d ≤ B (C2) ∀[vd] ∈ S : y vd ∈ [0, 1] (C3)
In the above formulation, y is a n × m decision matrix and f + (y) is a concave extension of f .
f + (y) = max S∈S α S f (S) α S ≥ 0; S∈S α S ≤ 1; ∀v : S [vd] α S ≤ y vd (1)
We first prove that P.B is a relaxed version of P.A. Lemma 2. Assume Θ * is the optimal solution to P.A and y + is the optimal solution to P.B, we have f + (y * ) ≥ S∈S θ * S f (S).
Proof.Given the optimal policy Θ * , for every u-c pair
d∈D y * vd = d∈D S [vd] θ * S ≤ S∈S θ * S = 1, thus condition (C1) is satisfied.
2.
S∈S θ * S c(S) ≤ B, e.g., the expected cost of any coupon allocation under Θ * is no larger than B. Because
[vd]∈S y * vd p v (d)d is the expected cost of Θ * , we have [vd]∈S y * vd p v (d)d ≤ B, thus condition (C2) is satisfied. 3. S∈S θ S = 1. Because ∀[vd] ∈ S : y vd is the probabil- ity that [vd] is offered by Θ * , we have ∀[vd] ∈ S : y vd ∈ [0, 1], thus condition (C3) is satisfied.
On the other hand, by setting α S = θ S for every S ∈ S in (1), we have f + (y * ) ≥ S∈S θ * S f (S).
Assume g + is the concave extension of g, we next prove that g + (y) is an approximate of f + (y).Lemma 3. f + (y) ≤ (1 + )g + (y)
Proof.Given any y, assume the value of f + (y) is achieved at {α
* A |A ⊆ V}, we have A⊆V α * A f (A) ≤ A⊆V α * A (1 + )g(A) = (1 + ) A⊆V α * A g(A) ≤ (1 + )g + (y).
Algorithm Design
In this section, we present a greedy algorithm that achieves a bounded approximation ratio.Our general idea is to first find a fractional solution with a bounded approximation ratio and then round it to an integral solution.
Continuous Greedy
In [Vondrák, 2008] they develop a continuous greedy algorithm based on the multilinear extension in order to maximize a submodular monotone function over a matroid constraint.We extend their results to non-sumbodular maximization subject to a partition matroid and knapsack constraints.We use 1 vd to denote a n × m matrix with entry (v, d) one and all other entries zero.Given two matrices a and b, let a ⊕ b denote the coordinate-wise maximum.Define F x ([vd]) = F (x ⊕ 1 vd ) − F (x).A detailed description of our algorithm is listed in Algorithm 1.
Algorithm 1 Continuous Greedy 1: Set δ = 1/(nm) 2 , t = 0, f (∅) = 0. 2: while t < 1 do 3:
Let R(t) contain each [vd] independent with probability y vd (t).
4:
For each [vd] ∈ S, estimate
ω vd = E[f (R(t) ∪ {[vd]})] − E[[f (R(t)) ≥ (1−e −(1+ 2 n 1+ ) )(1− ) 1+(2n+1) f + (y + ).
Proof.As proved in [Calinescu et al., 2011], if g is a submodular function, g + (y) ≤ min S⊆S (g(S) +
[vd]∈S y vd g S ([vd])).Let y + denote the optimal solution to problem P.B, assume y(t) is our solution at round t, then for every round t, we have
g + (y + ) ≤ min S∈S (g(S) + [vd]∈S y + vd g S ([vd])) ≤ G(y(t)) + [vd]∈S y + vd G y(t) ([vd]) ≤ 1 1 − F (y(t)) + [vd]∈S y + vd 1 1 − F (y(t) ⊕ 1 vd ) − 1 1 + F (y(t)) It follows that 1 − 1 + f + (y + ) ≤ (1 − )g + (y + ) ≤ F (y(t)) + [vd]∈S y + vd F (y(t) ⊕ 1 vd ) − 1 − 1 + F (y(t)) = F (y(t)) + [vd]∈S y + vd (F (y(t) ⊕ 1 vd ) − F (y(t))) + [vd]∈S y + vd 2 1 + F (y(t))(2)
The first inequality is due to Lemma 3. Let y denote the optimal solution to problem P.C in Algorithm 1 at round t, then we have
1 − 1 + f + (y + ) − (1 + [vd]∈S y + vd 2 1 + )F (y(t)) ≤ [vd]∈S y + vd F y(t) ([vd]) ≤ [vd]∈S y vd F y(t) ([vd]) (3)
The first inequality is due to (2) and the second inequality is because y is the optimal solution to problem P.C.According to Line 7, the increased value of our solution at round t + δ is at least
F (y(t + δ)) − F (y(t)) = [vd]∈S δy vd [v d ] =[vd] (1 − δy v d )F y(t) ([vd]) ≥ [vd]∈S δy vd (1 − δ) mn−1 F y(t) ([vd]) = δ(1 − δ) mn−1 [vd]∈S y vd F y(t) ([vd]) ≥ δ(1 − mnδ) [vd]∈S y vd F y(t) ([vd]) = δ(1 − 1 mn ) [vd]∈S y vd F y(t) ([vd])(4)
The last inequality is due to δ = 1 (mn) 2 .( 3) and ( 4) together imply that
F (y(t + δ)) − F (y(t)) ≥ δ(1 − 1 mn ) 1− 1+ f + (y + ) − (1 + [vd]∈S 2 y + vd 1+ )F (y(t)) ≥ δ(1 − 1 mn ) 1− 1+ f + (y + ) − (1 + 2 n 1+ )F (y(t)) (5) ≥ δ (1 − 1 mn ) 1− 1+ f + (y + ) − (1 + 2 n 1+ )F (y(t))(6)
Inequality ( 5) is due to
[vd]∈S y + vd ≤ n. Define ∆ t = (1 − 1 mn ) 1− 1+ f + (y + ) − (1 + 2 n 1+ )F (y(t)) , according to (6), we have ∆ t+δ = (1 − δ(1 + 2 n 1+ ))∆ t , thus ∆ 1/δ = (1 − δ(1 + 2 n 1 + )) 1/δ ∆ 0 = e −(1+ 2 n 1+ ) ∆ 0
It follows that
(1+ 2 n 1 + )F (y( 1 δ )) ≥ (1−e −(1+ 2 n 1+ ) )(1− 1 mn ) 1 − 1 + f + (y + ) = (1 − e −(1+ 2 n 1+ ) − o(1)) 1 − 1 + f + (y + )
(o(1) can be removed when choosing small enough δ [Vondrák, 2008] )
⇒ F (y( 1 δ )) ≥ (1−e −(1+ 2 n 1+ ) )(1− ) 1+(2n+1) f + (y + )
Rounding
In the rest of this paper, we use y to denote y( 1 δ ) for short.After obtaining y, we next round the fractional solution to integral solutions.Notice that classic rounding approach relying on the submodularity of the utility function, such as pipage rounding [Calinescu et al., 2011], can not work directly on a general function.
We first introduce a dummy coupon with value 0 and define y v0 = 1 − d∈D y vd .For each user v ∈ V, we assign exactly one discount to her, discount d ∈ D ∪ {0} to user v with probability y vd .The returned solution is denoted as T .We next prove that T is feasible and its expected cascade E[f (T )] is close to the optimal solution.
Theorem 1.Our rounding approach returns a feasible solution T to problem P.A, and
E[f (T )] ≥ βf + (y + ) where β = 1− 1+ n (1−e −(1+ 2 n 1+ ) )(1− ) 1+(2n+1)
.
Proof.We first prove the feasibility of our rounding approach.It is easy to verify that our solution satisfied C1, this is because each user receives at most one coupon.Because each u-c pair is selected with probability y vd and y is a feasible solution to problem P.B, the expected cost of T is
d∈D y vd p v (d)d ≤ B (C2 is satisfied). We next prove that E[f (T )] ≥ 1− 1+ n F(
y) by induction on n.First assume that n = 1 and S = S 1 , e.g., there is only one user.Let R be a set in which each u-c pair [vd] appears with probability y vd , thus E[f (R)] = F (y).Then,
E[f (R)] = R⊆S Pr[R]f (R) ≤ R⊆S (1 + ) Pr[R]g(R) ≤ R⊆S (1 + ) Pr[R] [vd]∈R g([vd]) (due to submodularity of g) ≤ R⊆S 1 + 1 − Pr[R] [vd]∈R f ([vd]) = 1 + 1 − Pr [[vd] ∈ R] f ([vd]) = 1 + 1 − E[f (T )] Now consider n > 1. Define T = T ∩ (S 1 ∪ S 2 • • • ∪ S n−1 ), T = T ∩ S k and R = R ∩ (S 1 ∪ S 2 • • • ∪ S k−1 ), R = R ∩ S k . For a given T , define f T (S) = f (T ∪ S). We have (1 − )g T (S) ≤ f T (S) ≤ (1 + )g T (S), because g T (S) is a submodular function of S, f (T ∪ S) is an -approximate submodular function of S. E[f (T )] = E[f (T ∪ T )] = T Pr[T ]E[f T (T )] ≥ 1 − 1 + T Pr[T ]E[f T (R )] (by induction) = 1 − 1 + E[f (T ∪ R )](7)
Similarly, for a given R , f R (S) is an approximate submodular function of S.
E[f (T ∪ R )] = R Pr[R ]E[f R (T )] ≥ 1 − 1 + n−1 R Pr[R ]E[f R (R )] = 1 − 1 + n−1 E[f (R ∪ R )](8)
Therefore, we have
E[f (T )] ≥ 1 − 1 + n E[f (R)] (9) ≥ 1 − 1 + n (1 − e −(1+ 2 n 1+ ) )(1 − ) 1 + (2n + 1) f + (y + )
The first inequality is due to ( 7) and ( 8), and the second inequality is due to Lemma 4.
Extension: Incorporating Distribution Cost
We now discuss one extension of our analysis thus far.The difference between the extended model and the previous model is that in the new model, we add one more constraint to Definition 1.In particular, we assume a feasible policy can not allocate coupons to more than K users.This additional constraint models the fact that the company only have limited resource to produce and distribute coupons to different users.
• (Coupon Distribution Budget Constraint) ∀θ S > 0 : |S| ≤ K, e.g., at most K users receive a coupon.
Similar to the previous model, we formulate our problem P.A + as follows.
P.A + maxΘ S∈S θSf (S) subject to:
∀θS > 0, ∀v : |Sv ∩ S| ≤ 1 S∈S θSc(S) ≤ B S∈S θS = 1 ∀θS > 0 : |S| ≤ K (Coupon Distribution Budget)
We follow a similar idea used in the previous section to design our algorithm, e.g., compute a fractional solution first and then round it to integral solution.However, to tackle the new challenge brought by the additional constraint, we need a brand new design of our rounding approach to ensure the feasibility of the final solution.We first introduce a new problem P.B + as follows.
P.B + Maximize f + (y) subject to:
(C1) ∼ (C3) [vd]∈S y vd ≤ K (C4)
Continuous Greedy Algorithm
We present the continuous greedy algorithm in Algorithm 2. The only difference between Algorithm 2 and Algorithm 1 is that in Algorithm 2, we redefine problem P.C + to incorporate constraint (C4).Based on a similar proof of Lemma 4, we can prove the following lemma.This bound is slightly better than Lemma 4, e.g., n is replaced by K. Lemma 5. Let y denote the solution returned from Algorithm 2 and y + denote the optimal solution to problem P.B + , we have
F (y) ≥ (1−e −(1+ 2 K 1+ ) )(1− ) 1+(2K+1) f + (y + ).
Rounding
We first notice that directly applying the previous rounding approach may violate constraint (C4), e.g., the number of users who receive coupons could be larger than K.We next design a brand new rounding approach that satisfies all constraints.The general idea of our new approach can be described as follows: partition all users into two groups, then apply a simple randomized rounding to each group, and the one with larger utility is returned as the final solution.
Let Z v = u∈{1,2,••• ,v} d∈D y ud .We first partition all users into two groups G 1 and G
2 . G 1 = {v| Z v − Z v−1 = 1} and G 2 = V \ G 1 .
Then we apply a simple randomized rounding to each group as follows:
• Rounding G 1 : The rounding approach used for G 1 is similar to the one used in the previous section.We first introduce a dummy coupon with value 0 and define y v0 = 1 − d∈D y vd .For each user in G 1 , we assign exactly one discount to her, discount d to user v with probability y vd .The returned solution is denoted as
T 1 . • Rounding G 2 : Given G 1 , we can naturally partition G 2 into |G 1 | subgroups: {G l 2 |l = 1, 2, • • • , |G 1 |}. The l-th subgroup of G 2 is defined as G l 2 = {v : u l < v < u l+1
} where u l denotes the index of the l-th user in G 1 .For every subgroup G l 2 , we introduce a dummy u-c pair with an arbitrary user v ∈ G l 2 and coupon value 0, and define y v0 = 1 − u∈G l 2 d∈D y ud .We select exactly one u-c pair from each subgroup, discount d to user v with probability y vd .The returned solution is denoted as T 2 .
• We compare the expected cascade from the above two solutions and choose the one with larger value as the final output.Recall that we use R to denote a set in which each u-c pair [vd] appears with probability y vd .We partition R into two subsets R 1 and R 2 .R 1 (resp.R 2 ) contains all u-c pairs whose user is from G 1 (resp.G 2 ).Similar to the proof of (9), we can prove the following lemma.Lemma 6.Both T 1 and T 2 are feasible solutions to
P.A + , and E[f (T 1 )] ≥ 1− 1+ n E[f (R 1 )] and E[f (T 2 )] ≥ 1− 1+ n E[f (R 2 )]
We next provide the performance bound of our solution.Theorem 2. The expected cascade of our solution is lower bounded by max{E
[f (T 1 )], E[f (T 2 )]} ≥ β f + (y + ) where β = 1 2 ( 1− 1+ ) n+1 (1−e −(1+ 2 K 1+ ) )(1− ) 1+(2K+1) . Proof. Because f is an -approximate submodular function, we have f (R 1 ) + f (R 2 ) ≥ (1 − )(g(R 1 ) + g(R 2 )) ≥ (1 − )g(R) ≥ 1− 1+ f (R).
As proved in Lemma 6, we have
E[f (T 1 )] ≥ 1− 1+ n E[f (R 1 )] and E[f (T 2 )] ≥ 1− 1+ n E[f (R 2 )]. Thus max{E[f (T 1 )], E[f (T 2 )]} ≥ 1 2 ( 1− 1+ ) n+1 E[f (R)] ≥ 1 2 ( 1− 1+ ) n+1 (1−e −(1+ 2 K 1+ ) )(1− ) 1+(2K+1)
f + (y + ).The last inequality is due to Lemma 5.
Performance Evaluation
We use Independent Cascade (IC) model as the information diffusion model.We set the propagation probability of each directed edge uv to be κ/N in (v) where N in (v) is the indegree of v.We vary the value of κ and examine its effect on the quality of the solutions.Coupon values normally range from 0 to 1 in steps of 0.1.Regarding the coupon adoption probabilities, we randomly select 75% nodes to assign p v (d) = 3 √ d, and 20% nodes to assign p v (d) = d, and 5% nodes to assign p v (d) = d 2 as their adoption probability functions.We compare our results with two benchmark solutions: Greedy and Random.Greedy starts with an empty seed set, in each iteration, it selects the u-c pair with the largest benefit cost ratio (the ratio of the increased expected cascade of the expected cost) and add it to the seed set.Random randomly selects a u-c pair in each iteration and add it to the seed set.This process is repeated until the budget is exhausted.Figure 1 shows the expected cascade yielded by our algorithm and baselines when budget B ranges from 10 to 100.We test the scenario with different influence probabilities κ ∈ {0.8, 1}.We observe that our solution (CG) consistently outperforms the runner-up Greedy.The gap between CG and Greedy becomes even larger as B increases.
Conclusion
In this paper, we study coupon allocation problem in social networks.Our framework allows a general utility function and more complicated constraints.Therefore, existing techniques relying on the submodularity of the utility function can not apply to our problem directly.We propose a novel approximate algorithm with approximation ratio depending on .Although we limit our attention to coupon allocation problem in this paper, our results apply to a broad range of approximate submodular maximization problems.
Algorithm 2
2
Continuous Greedy 1: Replace P.C in Algorithm 1 by P.C + P.C + : Maximize [vd]∈S ω vd y vd subject to: Conditions (C1)∼(C4)
Figure 1 :
1
Figure 1: Expected cascade vs. budget.
Table 1 :
1
Symbol table.
[vd] ∈ S, we define y * vd as the probability that [vd] is offered by Θ * , e.g., y * vd = S [vd] θ * S .We first prove that y * is a feasible solution to P.B.Because Θ * is a feasible policy, we have 1.∀θ * S > 0 : |S v ∩ S| ≤ 1, e.g., every user receives at most one coupon under Θ * .It follows that ∀v ∈ V :
Maximizing a monotone submodular function subject to a matroid constraint. Calinescu, Parinya Chalermsook, Atish Das Sarma, Ashwin Lall, and Danupon Nanongkai. ACM2011. 2011. 2015. 201540SIAM Journal on Computing
Information and influence propagation in social networks. Chen , Synthesis Lectures on Data Management. 542013. 2013
Thibaut Horel and Yaron Singer. Maximization of approximately submodular functions. Cohen, Advances in Neural Information Processing Systems. Horel and Singer2014. 2014. 2016. 2016Proceedings of the 23rd ACM CIKM
A generalization of submodular cover via the diminishing return property on the integer lattice. Kempe, Jure Leskovec, Andreas Krause, Carlos Guestrin, Christos Faloutsos, Jeanne VanBriesen, and Natalie Glance. Soma and YoshidaACM2003. 2003. 2017. 2007. 2007. 2015. 2015Advances in Neural Information Processing Systems
Optimal approximation for the submodular welfare problem in the value oracle model. Vondrák, Proceedings of the fortieth annual ACM symposium on Theory of computing. the fortieth annual ACM symposium on Theory of computingACM2008. Jan Vondrák. 2008
Continuous influence maximization: What discounts should we offer to social network users?. Yang , Proceedings of the 2016 ACM SIGMOD International Conference on Management of Data. the 2016 ACM SIGMOD International Conference on Management of DataACM2016. 2016
| [
-0.22170580923557281,
-0.016634682193398476,
-0.05561171472072601,
-0.13070383667945862,
0.06274281442165375,
-0.08527491986751556,
0.07381279766559601,
0.14631488919258118,
0.009863169863820076,
0.07866300642490387,
0.05550362169742584,
0.03220779821276665,
0.24887841939926147,
0.10709735... |
Optimal Feedback Stabilizing Control of Bounded Jacobian Discrete-Time Systems via Interval Observers
Mohammad Khajenejad
Optimal Feedback Stabilizing Control of Bounded Jacobian Discrete-Time Systems via Interval Observers
BE29479AF636169E2DDD62CC1D8FC282
This paper addresses optimal feedback stabilizing control for bounded Jacobian nonlinear discrete-time (DT) systems with nonlinear observations, affected by state and process noise.Instead of directly stabilizing the uncertain system, we propose stabilizing a higher-dimensional interval observer whose states enclose the true system states.Our nonlinear control approach introduces additional flexibility compared to linear methods, compensating for system nonlinearities and allowing potentially tighter closed-loop intervals.We also establish a separation principle, enabling independent design of observer and control gains, and derive tractable linear matrix inequalities, resulting in a stable closed-loop system.
I. INTRODUCTION
In many real-world applications, solving estimation and control problems is complicated by the presence of significant nonlinearities and uncertainties in process models.For instance, parameter identification and system modeling in fields like systems biology and neuroscience are highly complex due to inherent nonlinear dynamics [1].Similarly, collaborative robotics, where multiple agents-including humans-interact, introduces considerable uncertainty, making accurate modeling and control challenging [2].In such contexts, these uncertainties cannot be ignored and must be explicitly accounted for in the design process, necessitating adjustments to both control and estimation objectives.On the other hand, traditional control techniques often rely on precise system models, which can be difficult to obtain or maintain in practical applications due to noise, modeling errors, and external disturbances.This makes the design of estimation-based control approaches for nonlinear systems extremely important, particularly in cases where the system faces bounded uncertainties with unknown distributions or stochastic characteristics-rendering typical Kalman filterbased approaches inapplicable.
In such cases set-valued, and in particular interval-valued observers [3]- [6] have been leveraged to calculate a set (interval) of admissible values for the state at each instant of time using input-output information and the bounds on uncertainty [7]- [11].The interval length is minimized by directly relying on monotone systems theory [12] to obtain cooperative observer error dynamics, by leveraging interval arithmetic or Müller's theorem-based approaches [13], or by designing observer gains via solving linear, semidefinite or mixed integer programs [14]- [16], making the gains proportional to the magnitudes of the model uncertainties.
In the context of control design, and in particular for linear continuous-time (CT) systems, the work in [17] proposed an M. Khajenejad is with the Departments of Mechanical Engineering and Electrical and Computer Engineering, University of Tulsa, Tulsa, OK, USA.(e-mail: mohammad-khajenejad@utulsa.edu.)interval observer-based state feedback controller for switched linear systems, while [18] proposed a framework for semiglobal interval observer-based robust control of linear timeinvariant (LTI) systems subject to input saturation.
Moreover, concerning nonlinear settings, the work in [19] introduced a dynamic output feedback approach based on an interval state observer design for a class of nonlinear continuous-time (CT) systems, which was restricted to linear observations and did not consider measurement noise.Similarly, the research in [20] proposed a Luenberger-like interval observer methodology for nonlinear CT systems with linear observations and without taking to account sate and measurement noise.Recently, in the research in [21] a nonlinear feedback control strategy was proposed for a class of nonlinear CT systems using interval estimates, where sufficient conditions for stability of estimation and regulation errors were formulated using linear matrix inequalities (LMI)s.However, non of these works considered nonlinear discrete-time (DT) systems with nonlinear observations and state and measurement noise.
Contributions.To bridge this gap, this paper considers optimal stabilizing feedback control of bonded Jacobian nonlinear DT systems with nonlinear observations which are subject to state and process noise.We show that instead of stabilizing the true uncertain system, we can stabilize a higher dimensional certain framer system, i.e., an interval observer, whose states contain the states of the actual state from below and above.our nonlinear control approach benefits from an additional degree of freedom compared to the linear approach in [19].This extra gain compensates for the potential dynamic instabilities that are due to the system nonlinearities and expands the feasible set of admissible control signals, potentially resulting in tighter closed-loop intervals.Moreover, we provide a separation principle showing that the observer and control gains can be designed separately.This paves the way for the ability to obtain tractable LMIs to design control gains.II.PRELIMINARIES Notation.R n , R n×p , D n , N, N n denote the n-dimensional Euclidean space and the sets of n by p matrices, n by n diagonal matrices, natural numbers and natural numbers up to n, respectively.For M ∈ R n×p , M i,j denotes M 's entry in the i'th row and the j'th column,
M ⊕ ≜ max(M, 0 n×p ), M ⊖ = M ⊕ − M and |M | ≜ M ⊕ + M ⊖ ,
where 0 n×p is the zero matrix in R n×p and 0 n is the zero vector in R n , while sgn(M ) ∈ R n×p is the element-wise sign of M with sgn(M i,j ) = 1 if M i,j ≥ 0 and sgn(M i,j ) = −1, otherwise.Furthermore, if p = n, M ≻ 0 n×n and arXiv:2410.09222v1[eess.SY] 11 Oct 2024 M ≺ 0 n×n (or M ⪰ 0 n×n and M ⪯ 0 n×n ) denote that M is positive and negative (semi-)definite, respectively.Finally, diag(A 1 , . . ., A n ) denotes a block diagonal matrix with A 1 , . . ., A n being its diagonal block matrix entries, while diag n (A) ≜ diag(A, . . ., A n times
). Finally I n denotes the identity matrix in R n .
Next, we introduce some useful definitions and results.
Definition 1 (Interval, Maximal and Minimal Elements, Interval Width).An (multi-dimensional) interval I ≜ [s, s] ⊂ R n is the set of all real vectors x ∈ R n that satisfies s ≤ x ≤ s, where s, s and ∥s − s∥ ∞ ≜ max i∈{1,••• ,n} s i are called minimal vector, maximal vector and interval width of I, respectively.An interval matrix can be defined similarly.
Proposition 1. [14, Lemma 1] Let A ∈ R n×p and x ≤ x ≤ x ∈ R n . Then, A + x − A − x ≤ Ax ≤ A + x − A − x. As a corollary, if A is non-negative, Ax ≤ Ax ≤ Ax.
Definition 2 (Jacobian Sign-Stability).A mapping f : X ⊂ R n → R p is (generalized) Jacobian sign-stable (JSS), if its (generalized) Jacobian matrix entries do not change signs on its domain, i.e., if either of the following hold:
∀x ∈ X , ∀i ∈ N p , ∀j ∈ N n , J f (x) i,j ≥ 0 (positive JSS) ∀x ∈ X , ∀i ∈ N p , ∀j ∈ N n , J f (x) i,j ≤ 0 (negative JSS),
where J f (x) denotes the Jacobian matrix of f at x ∈ X .
Proposition 2 (Mixed-Monotone Decomposition). [22, Proposition 2] Let f : X ⊂ R n → R p and suppose ∀x ∈ X , J f (x) ∈ [J f , J f ],
where J f , J f are known matrices in R p×n .Then, f can be decomposed into a (remainder) affine mapping Hx and a JSS mapping µ(•), in an additive form:
∀x ∈ X , f (x) = µ(x) + Hx, (1)
where H is a matrix in R p×n , that satisfies the following
∀(i, j) ∈ N p × N n , H i,j = (J f ) i,j ∨ H i,j = (J f ) i,j .(2)
Proposition 3 (Tight and Tractable Decomposition Functions for JSS Mappings [22,Proposition 4 & Lemma 3]).Let µ : Z ⊂ R nz → R p be a JSS mapping on its domain.Then, it admits a tight decomposition function for each µ i , i ∈ N p as follows:
µ d,i (z 1 , z 2 )=µ i (D i z 1 +(I nz −D i )z 2 ),(3)
for any ordered z 1 , z 2 ∈ Z, where D i is a binary diagonal matrix determined by which vertex of the interval
[z 2 , z 1 ] or [z 1 , z 2 ] that maximizes (if z 2 ≤ z 1 ) or minimizes (if z 2 > z 1 )
the function µ i that can be found in closed-form as:
D i = diag(max(sgn(J µ i ), 0 1,nz )).(4)
Furthermore, for any interval domain [z z] ⊆ Z, the following inequality holds:
µ d (z, z) − µ d (z, z) ≤ F µ (z − z),(5)
where
µ d = [µ d,1 , . . . , µ d,p ] ⊤ and F µ = J ⊕ µ + J ⊖ µ .(6)
Finally, if µ is computed through the mixed-monotone de-composition in Proposition 2, then
J µ = J f − H and J µ = J f − H.(7)
III. PROBLEM FORMULATION
System Assumptions.Consider the following nonlinear discrete-time (DT) system:
G : x k+1 = f (x k ) + Bu k + W w k y k = g(x k ) + Du k + V v k ,(8)
where
x k ∈ X ⊂ R n , u k ∈ R m , y k ∈ R l , w k ∈ W ≜ [w, w] ⊂ R nw and v k ∈ V ≜ [v, v] ⊂ R nv are continuous state, control input, output (measurement)
, process disturbance and measurement noise signals, respectively.Furthermore, f : X → R n and g : X → R l are known, nonlinear vector fields, and
B ∈ R n ×R n , W ∈ R n ×R nw , D ∈ R l ×R b and V ∈ R l × R nv are known matrices.
Assumption 1.The mappings f and g are known, differentiable and have bounded Jacobians, i.e., satisfy
J f ≤ J ν (x) ≤ J ν , ∀ν ∈ {f, g}, ∀x ∈ X ,
where J f and J g are the Jacobian matrix functions and
J f , J f ∈ R n×n , J g , J g ∈ R l×n are priori known matrices.
Based on Assumption 1 and by leveraging Proposition 2, the matrices A ∈ R n×n and C ∈ R l×n are chosen such that the following decompositions hold (cf.Definition 2 for JSS mappings):
∀x ∈ X : f (x) = Ax + ϕ(x) h(x) = Cx + ψ(x) s.t. ϕ, ψ are JSS in X . (9)
Recall that according to Proposition 3, the JSS mappings ϕ and ψ admit matrices F ϕ and F ψ that can be computed via (6) and satisfy (5).Without loss of generality, we assume F ϕ is invertible.The reason is that by construction, F ϕ is a nonnegative matrix (cf.( 6)).So, even if the initially computed F ϕ is not invertible, one can increase its diagonal elements until the modified F ϕ becomes a diagonally dominant, and so invertible matrix [23].Furthermore, since the modified F ϕ is not less than the initial one, it still satisifes (5) given the non-negativity of all items in both sides of the inequality.We also assume the following.
Assumption 2. The initial state x 0 satisfies x 0 ∈ X 0 = [x 0 , x 0 ], where x 0 and x 0 are known initial state bounds, and the values of the output/measurement y k signals are known at all times.
Our goal is to design the control input signal u k as a (implicit) function of system measurements/outputs to stabilize the closed-loop DT nonlinear system (8)- (9).Due to the existing uncertainties, we do not assume that the state is measurable (even the initial state is uncertain), and we only measure the output y k .Problem 1.Given the nonlinear system in (8)-( 9), as well as Assumptions 1 and 2, synthesize a stabilizing feedback control input u k for the plant G so that the resulting closedloop system is asymptotically stable.
IV. PROPOSED CONTROL DESIGN
Before discussing our control design strategy, we first briefly introduce the notions of framer and interval observer which we extensively use throughout the paper.Definition 3 (Correct Interval Framers).Given the nonlinear plant G, the sequences of signals {x k , xk} ∞ k=0 in R n are called upper and lower framers for the states of (8), if
∀k ∈ [0, ∞), x k ≤ x k ≤ x k . (10)
In other words, starting from the initial interval x 0 ≤ x 0 ≤ x 0 , the true state of the system in (8), x k , is guaranteed to evolve within the interval flow-pipe [x k , x k ], for all k ≥ 0.
Finally, any dynamical system Ĝ whose states are correct framers for the states of the plant G, i.e., any (tractable) algorithm that returns upper and lower framers for the states of plant G is called a correct interval framer system for (8).
Definition 4 (Framer Error).Given state framers
x k ≤ x k , k ≥ 0, ε k ≜ x k − x k ,∥ε k ∥ 2 ≤ β(∥ε 0 ∥, k) + ρ(∥δ∥ ℓ∞ ), ∀k ≥ 0,(11)
where δ ≜ [δ ⊤ w δ ⊤ v ] ⊤ , β and ρ are functions of classes KL and K ∞ , respectively, and ∥δ∥ ℓ∞ = sup k≥0 ∥δ k ∥ 2 = ∥δ∥ 2 is the ℓ ∞ signal norm.An ISS interval framer is called an interval observer.
Our proposed control strategy has the following steps:
(i) Since the actual state of the system in ( 8)-( 9) is uncertain and not measured, we first construct a corresponding certain and robust framer system, that given the output (measurement) signal and by construction, returns upper and lower interval-valued estimates of the state of the actual system, given any control signal u k , any to-be-designed observer gain, and for any realization of the bounded noise and disturbance signals.(ii) Then, we consider a state feedback control for the framer system constructed in (i) using to-be-designed control gains.The goal is to stabilize the framer system which results in a stable actual system.(iii) Finally, by plugging the controls from (ii) into the framer system in (i), we obtain the closed-loop framer system.We stabilize the closed-loop system by designing the observer and controller gains, which we show that can be done separately.This results in an input-tostate stable closed-loop system for the actual plant.
A. Interval Framers
Given the nonlinear plant G, in order to address Problem 1, we first propose an interval observer (cf.Definition 3) for G similar to [15], through the following dynamical system:
x k+1 = (A−LC) ⊕ x k − (A−LC) ⊖ x k + (LV ) ⊖ v−(LV ) ⊕ v +ϕ d (x k , x k ) +Ly k +(B−LD)u k + W ⊕ w − W ⊖ w +L ⊖ ψ d (x k , x k ) − L ⊕ ψ d (x k , x k ) x k+1 = (A−LC) ⊕ x k − (A−LC) ⊖ x k + (LV ) ⊖ v−(LV ) ⊕ v +L ⊖ ψ d (x k , x k ) − L ⊕ ψ d (x k , x k ) +ϕ d (x k , x k ) +Ly k +(B−LD)u k + W ⊕ w − W ⊖ w (12)
where ϕ d : R n × R n → R n and ψ d : R n × R n → R l are tight mixed-monotone decomposition functions of the JSS mappings ϕ and ψ, computed via Proposition.Moreover, L ∈ R n×l is a to-be-designed observer gain matrix.Defining ε k ≜ x k − x k , we obtain the following system from ( 12) that governs the dynamics of the framer errors:
ε k+1 = |A − LC|ε k + δ ϕ k +|L|δ ψ k + |LV |δ v + |W |δ w , (13) where δ ρ k ≜ ρ d (x k , x k ) − ρ(x k ), δ ρ k ≜ ρ(x k )−ρ d (x k , x k ), δ α ≜ α k − α k , ∀ρ ∈ {ϕ, ψ}, ∀α ∈ {w, v}.(14)
The following proposition ensures that ( 13) is an interval framer for ( 8)-( 9).
Proposition 4. The system in (12) constructs a framer system for the plant in (8)-( 9) for all values of the control signal u k , all realizations of the bounded noise and disturbance v k , w k and all values of the gain L. Consequently, (13) is a positive system.Furthermore, if L is a solution to the SDP in [15, (17) and ( 19)], then (13) is an ISS system, i.e., (12) is an interval observer for (8)-( 9).
Proof. The proof follows the lines of [15, Theorems 1 & 2]
with the slight modification that the terms Bu k and Du k are added to the state and output equations, respectively, as well as to the corresponding framers, since they are treated as known variables when upper and lower framers are computed.
■
B. Closed-Loop System and Separation Principle
In this subsection we propose the following nonlinear state feedback control to stabilize the system in (12): (15) where K, K and K ν are to-be-designed control gain matrices in R m×n .The goal is to stabilize the framer system (12) which consequently stabilizes the trajectory of the actual closed-loop system [24], [25].
u k = Kx k − Kx k + K ν (ϕ d (x k , x k ) − ϕ d (x k , x k )),
It is worth emphasizing the additional degree of freedom of our nonlinear control approach, i.e, K ν compared to the linear control approach in [19].This extra to-be-designed gain, compensates for the potential dynamic instabilities that are due to the system nonlinearities and extends the feasible set of admissible control signals, hence potentially resulting in tighter closed-loop intervals.
Next, to obtain the dynamics of the closed-loop system, we plug u k from ( 15) into (12) and use the fact that
Ly k + (B − LD)u k = Bu k + L(y k − Du k ) = Bu k + Cx k + ψ(x k ) + V v k ,(16)
which results in the following closed-loop system:
x k+1 = ((A−LC) ⊕ + BK)x k − ((A−LC) ⊖ + BK)x k +(LV ) ⊖ v−(LV ) ⊕ v + LV v k + W ⊕ w − W ⊖ w +ϕ d (x k , x k ) + L ⊕ δ ψ k + L ⊖ δ ψ k + BK ν δ ϕ k + LCx k , x k+1 = ((A−LC) ⊕ − BK)x k − ((A−LC) ⊖ − BK)x k +(LV ) ⊖ v−(LV ) ⊕ v + LV v k + W ⊕ w − W ⊖ w +ϕ d (x k , x k ) − L ⊕ δ ψ k − L ⊖ δ ψ k + BK ν δ ϕ k + LCx k ,(17)
where δ ϕ k and δ ψ k are defined in (14).
The system in ( 17) still contains the actual state x k which is not measured and hence is not accessible.To resolve this issue, we apply a change if variabes and define the following sequences of upper and lower closed-loop errors for k ≥ 0:
e k ≜ x k − x k ⇒ x k = x k − e k , e k ≜ x k − x k ⇒ x k = x k + e k . (18)
Next, from ( 8) and the fact that
L(y k − Cx k − ψ(x k ) − Du k − V v k ) = 0, ∀k,
we obtain:
x k+1 = (A − LC)x k − Lψ(x k ) + ϕ(x k ) + W w k + Ly k − LV v k + (B − LD)u k .
Finally, combining this, (17), and the fact that M = M ⊕ − M ⊖ for any matrix M , we obtain the dynamics of the closedloop errors:
e k+1 = (A−LC) ⊕ e k − (A−LC) ⊖ e k + δ ϕ k − W w k +(LV ) ⊖ v−(LV ) ⊕ v + LV v k + W ⊕ w −W ⊖ w, e k+1 = (A−LC) ⊕ e k − (A−LC) ⊖ e k + δ ϕ k + W w k +(LV ) ⊖ v−(LV ) ⊕ v + LV v k + W ⊕ w −W ⊖ w,(19)
We are ready to sate our fist result, which shows that the augmented system of closed-loop framers and errors has a comparison system that is independent of x k , and can be stabilized by separately designing observer gain L, and the control gain matrices K, K, K ν .
Lemma 1 (Separation Principle).The augmentation of ( 17) and ( 19) can be stabilized by first designing a stabilizing observer gain L for the framer error system (13), and then synthesizing the state feedback control gains K, K, K ν , given L to stabilize the augmented system.
Proof.Augmenting ( 17) and (19), and using the following inequalities for ρ ∈ {ϕ, ψ} according to Proposition 3 and the fact that ρ d (x k , x k ) ≤ ρ(x k ) ≤ ρ d (x k , x k ), and hence:
δ ρ k =ρ d (x k , x k ) − ρ(x k ) ≤ ρ d (x k , x k ) −ρ d (x k , x k ) ≤ F ρ (x k − x k ) = F ρ (x k − x k + x k − x k ) = F ρ (e k + e k ),(20)
returns a comparison augmented system:
z k+1 ≤ Ãz k + λ(z k ) + Λη k ,(21)
where
η k ≜ [w ⊤ w ⊤ w ⊤ k v ⊤ v ⊤ v ⊤ k ] ⊤ , z ≜ [e ⊤ e ⊤ x ⊤ x ⊤ ] ⊤ , λ(z) ≜ [0 ⊤ n 0 ⊤ n ϕ ⊤ d (x, x) ϕ ⊤ d (x, x)] ⊤ , Λ ≜ W ⊕ −W ⊖ −W (LV ) ⊖ −(LV ) ⊕ LV −W ⊖ W ⊕ W −(LV ) ⊕ (LV ) ⊖ LV W ⊕ −W ⊖ 0 n,nw (LV ) ⊖ −(LV ) ⊕ LV −W ⊖ W ⊕ 0 n,nw −(LV ) ⊕ (LV ) ⊖ LV , Ã = [ Ã11 ] [ Ã12 ] 0 n×n 0 n×n [ Ã21 ] [ Ã22 ] 0 n×n 0 n×n [ Ã31 ] [ Ã32 ] [ Ã33 ] [ Ã34 ] [ Ã41 ] [ Ã42 ] [ Ã43 ] [ Ã44 ] .
Moreover, the block matrices inside à are as follows:
[ Ã11 ] ≜ (A − LC) ⊕ + F ϕ + |L|F ψ , [ Ã12 ] ≜ (A − LC) ⊖ + F ϕ + |L|F ψ , [ Ã21 ] ≜ (A − LC) ⊖ + F ϕ − |L|F ψ , [ Ã22 ] ≜ (A − LC) ⊕ + F ϕ − |L|F ψ , [ Ã31 ] ≜ −LC + |L|F ψ + BK ν F ϕ , [ Ã32 ] ≜ |L|F ψ + BK ν F ϕ , [ Ã33 ] ≜ (A − LC) ⊕ +BK + LC, [ Ã34 ] ≜ −(A − LC) ⊖ −BK, [ Ã41 ] ≜ −|L|F ψ + BK ν F ϕ , [ Ã42 ] ≜ LC − |L|F ψ + BK ν F ϕ , [ Ã43] ≜ −(A − LC) ⊖ + BK, [ Ã44 ] ≜ (A − LC) ⊕ −BK+LC.
The comparison system (21) has a linear component with state matrix Ã, as well as the Lipschitz nonlinear component λ(z).Note that λ is a locally Lipschitz mapping since ϕ has bounded Jacobin by Assumption 1 and Proposition 3, and hence is locally Lipschitz.Consequently, ϕ d is Lipschitz by construction (cf.(3) in Proposition 3).Since, Ã is a block lower trinagular matrix, its set of eigenvalues is a superset of the set of eigenvalues of the matrix Ãu ≜ Ã11 Ã12 Ã21 Ã22 which only depend on L.Moreover, the nonlinear vector function λ(z) does not affect the stability of Ãu due to its zero upper elements.Hence, the observer and controller gains can be designed separately to stabilize system (21).Moreover, by applying the last inequality in (20), it is straightforward to see that ( 19) admits a linear comparison system with the sate matrix Ãu .Hence, any observer gain that stabilizes (21) should stabilize (19) and vice versa.Finally, from the definitions of ε k , e k , e k , we have 0 n ≤ e k ≤ ε k and 0 n ≤ e k ≤ ε k .Therefore, any observer gain L that stabilizes the open loop framer error system (13), should stabilize (19), and consequently (21).
■
C. Control Design
Based on Lemma (1), the design of the observer and control gains can be done separately, where L can be designed first to stabilize (13).In our previous work [15] (also summarized in Proposition 4) we provided linear matrix inequalities, through which such an L can be computed.Given this observer gain, in order to obtain tractable LMIs to synthesize the stabilizing feedback control gains K, K, K ν , the main challenge to be addressed is to resolve the bilinearities between decision variables when applying the existing results on the stability of Lipschitz nonlinear DT systems to (21).The following theorem and its proof tackles this challenge by applying specific similarity transformations and change of variables.
Theorem 1. Suppose L ∈ R n×l is computed through Proposition 4, α > 0 is a chosen real constant (e.g., is a desired decay rate for the error system (19)) picked by the designer, and ϵ = 1
s.t. Γ − Q Q Q Â⊤ + Θ B⊤ I 4n * −αI 4n 0 4n×4n 0 4n×4n * * − 1 2 Q Q * * * Q − 2ϵΓ ≺ 0 16n×16n , −µI ñ Λ ⊤ Λ ⊤ * − 1 2 Q 0 4n×4n * * −Γ ≺ 0 n×n , I 4n Q Q Γ ⪰ 0 8n×8n ,(22)
where ñ ≜ 3(n w + n v ) is the dimension of the augmented noise vector η k ∈ R ñ and n ≜ ñ + 8n.Moreover, Â ∈ R 4n×4n and B ∈ R 4n×12n are defined as follows:
[ Âij ] = [ Ãij ], i ∈ {1, 2}, j ∈ {1, 2, 3, 4}, [ Â31 ] = LC + |L|F ψ , [ Â32 ] = |L|F ψ , [ Â33 ] = (A − Lc) ⊕ + LC, [ Â34 ] = −(A − LC) ⊖ , [ Â41 ] = −|L|F ψ , [ Â42 ] = LC − |L|F ψ , [ Â43 ] = −(A − LC) ⊖ , [ Â44 ] = (A − LC) ⊕ + LC, [ Bij ] = 0 n×3m , i ∈ {1, 2}, j ∈ {1, 2, 3, 4}, 0 n×m 0 n×m B , i ∈ {3, 4}, j ∈ {1, 2}, B 0 n×m 0 n×m , i ∈ {3, 4}, j = 3, 0 n×m −B 0 n×m , i ∈ {3, 4}, j = 4 .
Then, the augmented closed-loop system (21) is ISS and satisfies
∥z k ∥ 2 2 ≤ µ * ∥ wk ∥ 2 2 , ∀k,(23)
with the control gains K * , K * , K ν * that are obtained as follows:
K * = (Q −1 * Θ * ) ⊤ = diag 4 (diag(K * , K * , K ν * F ϕ )). (24)
Proof.First, note that the augmented system in (21)
≺ 0 16n×16n ,(25) −µI ñ Λ ⊤ P Λ ⊤ P * − 1 2 P 0 4n×4n * * −I 4n ≺ 0 n×n .(26)
(25) and ( 26) cannot be directly used to design the control gains due to the existence of the terms P Ã which contains bilinearities in the form of pre-and post-multiplication of matrix B with decision variables, i.e., the control gains.To overcome this difficulty, we apply two similarity transformations by pre-and post-multiplying the LMIs in ( 25) and ( 26) by diag(P −1 , I 4n , P −1 , P −1 ) and diag(I ñ, P −1 , P −1 ), respectively.This, combined with applying the change of variables Q = P −1 , and defining the new matrix variable
Γ that satisfies Γ ⪰ P −2 = Q 2 ⇔ I 4n Q Q Γ ⪰ 0 8n×8n by
Schur complements, returns the results.
■
V. ILLUSTRATIVE EXAMPLE
The effectiveness of our control design is illustrated by the following example.Consider a slightly modified version of the system in [26, Example 2] in the form of ( 8)-( 9) with:
A =
0.5000 −0.5975 0.3735 0.0457 0.3575 0.2500 0.3000 0.4017 0.1114 0.0227 0.4880 01384 0.2500 0.7500 0.7500 0.3838 0.0974 0.5000 0.2500 0.5000 0.0347 0.1865 −0.2500 0.5000 0.2500
, ϕ(x) = 0.1(sin(x 3 ) − x 3 ) 0.2(sin(x 4 ) − x 4 ) 0.3(sin(x 1 ) − x 1 ) 0 0.1(sin(x 2 ) − x 2 ) , B =
0.7 0.8 0 0.4 0.9 0.9 0.9 0.9 0.2 0.9 0.6 0.7 0 0.5 0. noise attenuation level µ * = 1.6137.The second to sixth plots in Figure 1 show the trajectories of the closed-loop stabilized framers as well as actual states, which as can be seen are asymptotically stable.
VI. CONCLUSION AND FUTURE WORK
In this paper, optimal feedback stabilizing control for bounded Jacobian nonlinear discrete-time systems with nonlinear observations, subject to state and process noise, was addressed.Rather than stabilizing the uncertain system directly, a higher-dimensional interval observer was stabilized, with its states containing the actual system states.The nonlinear control approach provided additional flexibility compared to linear methods, compensating for system nonlinearities and allowing tighter closed-loop intervals.A separation principle was established, enabling the independent design of observer and control gains, and tractable LMIs were derived for control gain design.Extending this approach to switching dynamics and hybrid systems, as well as other control strategies such as model predictive control will be considered for future work.
αγ 2 − 1 ,
21
where γ = ∥F ϕ ∥ ∞ is the Lipshitz constant of the decomposition function ϕ d .Let (µ * , Γ * , Q * , Θ * ) be a solution to the following SDP: min {µ>0,Γ≻04n×4n,Q≻04n×4n,Θ} µ
I 2 ψ
2
(x) = [0.1(cos(x 1 ) − x 1 ) 0.2(cos(x 2 ) + x 2 )] ⊤ , W = I 5 ,where W = [−.1 .1] 5 , V = [−.1 .1] 2 and X 0 = [−6 6]5 .The nonlinear system is unstable.Moreover, matrix A is unstable, which means the linear part of the system is itself unstable.The first plot in Figure1(i.e., in the upper left corner) shows the trajectory of all the states for the unstable open-loop system, where some of the state values grow unbounded as expected.Using Proposition 3 we computed F ϕ = ∥F ϕ ∥ ∞ = 0.6010, where ε 0 = 0.001 is a small number added to the diagonal entries of the original F ϕ to make it an invertible matrix.We set α = 0.1 which results in ϵ = 1 αγ 2 − 1 = 26.6854.Moreover, based on the separation principle results in Lemma 1, we fist obtained L = 0.1 0 0 0 0 −20.0999 1 0 0 0 by solving the SDP in[15, (17) and(19)] employing
Fig. 1 :
1
Fig. 1: Open-loop states (first plot), as well as the closed-loop upper and lower framers and actual states (second to sixth plots), returned by our proposed control design.YALMIP and MOSEK.Then, given L, we leveraged bisection and YALMIP again to solve the corresponding SDP in(22), which resulted in the following control gainsK * = −K * =
has a Lipschitz nonlinear component λ.This is because the vector field ϕ has bounded Jacobians by Assumption 1 and (7), and so is Lipschitz.Hence, ϕ d is also Lipschitz by construction (cf.(3) and (4) in Proposition 3), with the Lipschitz constant γ = ∥F ϕ ∥
I 4n − P I 4nÃ⊤ P 0 4n×4n * * *−αI 4n 0 4n×4n 0 4n×4n * − 1 P 2 P * * P − 2ϵI
(23)hen, by[26, Lemma 3],(21)is input-to-state stable and satisfies(23)if the following LMIs hold (which are the special cases of[26, (15)and (16)] with H being an identity matrix, while N and M are set to be zero matrices):
Dynamical systems in neuroscience. E M Izhikevich, 2007MIT press
Control and observer design for nonlinear finite and infinite dimensional systems. T Meurer, K Graichen, E D Gilles, 2005Springer Science & Business Media322
Interval observers for linear time-invariant systems with disturbances. F Mazenc, O Bernard, Automatica. 4712011
Interval observer design for LPV systems with parametric uncertainty. Y Wang, D M Bevly, R Rajamani, Automatica. 602015
Interval observers for continuous-time LPV systems with L1/L2 performance. S Chebotarev, D Efimov, T Raïssi, A Zolghadri, Automatica. 582015
Distributed resilient interval observer synthesis for nonlinear discrete-time systems. M Khajenejad, S Brown, S Martinez, arXiv:2401.155112024arXiv preprint
Near optimal interval observers bundle for uncertain bioreactors. M Moisan, O Bernard, J-L Gouzé, European Control Conference (ECC). IEEE2007
Interval observer design for consistency checks of nonlinear continuous-time systems. T Raïssi, G Videau, A Zolghadri, Automatica. 4632010
Ac ¸ıkmes ¸e. Synthesis of interval observers for bounded Jacobian nonlinear discrete-time systems. A M Tahir, B , IEEE Control Systems Letters. 2021
Interval observers for simultaneous state and model estimation of partially known nonlinear systems. M Khajenejad, Z Jin, S Z Yong, American Control Conference (ACC). 2021
Simultaneous input and state interval observers for nonlinear systems with full-rank direct feedthrough. M Khajenejad, S Z Yong, IEEE Conference on Decision and Control. 2020
Positive linear systems: theory and applications. L Farina, S Rinaldi, 2000John Wiley & Sons50
Guaranteed nonlinear state estimation for continuous-time dynamical models from discrete-time measurements. M Kieffer, E Walter, IFAC Proceedings Volumes. 200639
Interval state observer for nonlinear time varying systems. D Efimov, T Raïssi, S Chebotarev, A Zolghadri, Automatica. 4912013
H∞-optimal interval observer synthesis for uncertain nonlinear dynamical systems via mixed-monotone decompositions. M Khajenejad, S Z Yong, IEEE Control Systems Letters. 62022
l 1 -robust interval observer design for uncertain nonlinear dynamical systems. T Pati, M Khajenejad, S Praveen Daddala, S Z Yong, IEEE Control Systems Letters. 62022
Interval observer-based eventtriggered control for switched linear systems. Y E Wang, Y Gao, D Wu, B Niu, Journal of the Franklin Institute. 357102020
Semi-global interval observerbased robust control of linear time-invariant systems subject to input saturation. Z Zhang, J Shen, J Zhang, H Qiu, Circuits, Systems, and Signal Processing. 2024
Control of nonlinear and LPV systems: interval observer-based framework. D Efimov, T Raissi, A Zolghadri, IEEE Transactions on Automatic Control. 5832013
Control of nonlinear systems based on interval observer design. Z He, W Xie, IET Control Theory & Applications. 1242018
Interval observation and control for continuous-time Persidskii systems. D Efimov, A Polyakov, X Ping, IEEE Transactions on Automatic Control. 2024
Interval observer synthesis for locally Lipschitz nonlinear dynamical systems via mixed-monotone decompositions. M Khajenejad, F Shoaib, S Z Yong, American Control Conference (ACC). 2022
Block-diagonal solutions to Lyapunov inequalities and generalisations of diagonal dominance. A Sootla, Y Zheng, A Papachristodoulou, IEEE 56th conference on decision and control (CDC). IEEE2017
Global stability for mixed monotone systems. H L Smith, Journal of Difference Equations and Applications. 1410-112008
Mixed monotone decomposition of dynamical systems with application. T Chu, L Huang, Chinese science bulletin. 431998
LMI optimization approach to robust H∞ observer design and static output feedback stabilization for discrete-time nonlinear uncertain systems. M Abbaszadeh, Horacio J Marquez, International Journal of Robust and Nonlinear Control: IFAC-Affiliated Journal. 1932009
| [
-0.11955644190311432,
-0.10693094879388809,
-0.002328089904040098,
-0.11539255827665329,
-0.12920787930488586,
0.023794716224074364,
-0.025996388867497444,
0.04050247371196747,
0.02755717933177948,
0.09718164801597595,
-0.09192885458469391,
0.028308585286140442,
0.11276711523532867,
-0.038... |
SIMULATORS FOR QUANTUM NETWORK MODELLING: A COMPREHENSIVE REVIEW
August 23, 2024
Oceane Bel obel@pnnl.gov
Physical & Computational Sciences Directorate Pacific Northwest National Laboratory Richland
WAUSA
Mariam Kiran kiranm@ornl.gov
Computational Sciences and Engineering Division Oak Ridge National Laboratory Oak Ridge
TNUSA
SIMULATORS FOR QUANTUM NETWORK MODELLING: A COMPREHENSIVE REVIEW
August 23, 20247F6CD88EACBB2DB641A0E01F1E6036A3arXiv:2408.11993v1[quant-ph]Topics: Quantum networknetwork modelssimulatorsverification and validation
Quantum network research, is exploring new networking protocols, physics-based hardware and novel experiments to demonstrate how quantum distribution will work over large distances.Current work explores much of these concepts in simulations, that are developed to understand how quantum networking will be set up and researchers can experiment virtually.Exposing flaws in network designs, like unsustainable topologies, or develop protocols that efficiently utilize network resources, simulators can also help assess whether workloads are balanced across virtual machines in the network.However, much of these simulation models come without reliable verification methods, for testing performance in real deployments.In this paper, we present a review of, to the best of our knowledge, currently used toolkits for modeling quantum networks.With these toolkits and standardized validation techniques, we can lay down the foundations for more accurate and reliable quantum network simulators.
Introduction
Quantum networks are the next generation of communication networks that deliver entanglement and connect distributed quantum physics devices such as quantum computers, sensors and detectors [1,2,3,4].Instead of classical 'bits' (0s,1s), qubits are transmitted that can encode more information, by using the spin of the photons.Argued to be the next internet revolution, distributed quantum networks have shown case studies to process and communicate secure and highly accurate measurements, currently beyond the classical machines [5].
Industry quantum efforts are developing new hardware, protocols and tools that can enable quantum information exchange.These technologies can demonstrate reliable quantum communication with high rates of fidelity and automated error correction [6,7,8].Some of these approaches use discrete and continuous variable demonstrations, each bringing their own capabilities in the experiments [9], or transmission over fiber optical cable or free space point to point communication.Network loss plays a huge role in guaranteeing the validity of the quantum states, current demonstrations have only shown upto 300 km [10].With the help of quantum repeaters, one can extend these to longer distances such that quantum states can be refreshed or preserved [11,12,13].
Quantum network simulations are also being developed to help define use cases, and collect data to build reliable devices.Several efforts such as Qunet [14], ComNetsEmu [15], or Cisco's QnetLab are focused on developing kits that can interface with other simulations and provide a GUI, to build topology, collect parameters and investigate new protocols.These can demonstrate large-distance transmission using repeaters and help identify solutions to protocols that can utilize network resources effectively.However, these simulation toolkits, still lack robust testing and verification methods to verify the accuracy of simulated quantum networks and how these would translate in the real world hardware.
Developing quantum networks presents significant challenges for network providers and researchers.Some exploration in monitoring equipment and tools [16,17,18] are integrating quantum and optical channels, often with a transduction layer for quantum network overlay (Figure 1).Here, transduction is applied to quantum information transmitted from one physical system to another, where qubit frequencies are converted to optic and vice versa, utilizing the underlying infrastructure.Figure 1: An example of interfacing quantum over optical network layer.This includes: The DWDM (Dense Wavelength Division Multiplexing) exists in the physical layer of classical optical networks.TDC (Time-to-Digital Converter) is mainly used for synchronization between different nodes.EOM (Electro-Optic Modulator) manipulates the light signals to convert the frequency of a photon while preserving its quantum information.SNSPD (Superconducting Nanowire Single-Photon Detector) help perform measurements, Hong-Ou-Mandel (HOM) interference and RB (Rubidium) is an alkali metal element.
In this paper, we investigate and compare quantum network simulators that are being used to develop key concepts in quantum networking.These simulators model new technologies, use analytical models and compare physics operations derived from established equations.Having a standardized validation method will allow consistency within the research community.This survey focuses on reviewing existing theoretical works for simulating qubit behavior on communication channels, discussing on what is further needed in this space.
Motivation and Contributions
The goal of this paper is to review the current quantum network simulation toolkits and understand how these are being used.Identifying the use cases being modelled, the paper aims to identify the limitations each toolkit has.This paper serves as an introduction to the quantum network simulation research, covering the current landscape and identifying future needs for validating quantum network simulators.
In terms of validation, the paper aims to explore simple analytical models on how qubit models can be generated and tested for quantum networking.The paper is organized as follows: Section 2 discusses what quantum networks are designed for and its applications.Section 3 goes into details of example simulation platforms and their developments.Section 4 discusses the challenges in these platforms and how these can improved in Section 5. Finally, Section 6 concludes and presents future research directions in this area.
Challenges in Designing Quantum Network Simulators
The first design consideration is correctly modeling Quantum Nodes and Channels [19].Factors such as qubit connectivity, gate fidelity, and quantum channel characteristics [20], and scaling with the size of the quantum network while maintaining computational efficiency are all challenges for simulators.
The second consideration is realism [21] of the behavior of quantum operations on the network.Realistic quantum operations, such as gates, measurements, and entanglement generation, need to pay attention to the impact of noise and errors.This means that simulators need to have capabilities for simulating quantum error correction techniques.Using accurate quantum models to reflect the behavior of physical quantum systems, needs a tool to evaluate the performance of error correction codes and their effectiveness in mitigating the impact of these on quantum communication.
A third consideration, there is a need to develop a comprehensive benchmarking and validation framework to assess the performance of the simulator.This framework should include metrics for success rates, fidelity, speed, scalability, and resource utilization in entanglement distribution and other quantum communication tasks.It should also have a user-friendly interface, which allows users to setup, configure, and analyse quantum network simulations.It should provide tools for visualizing network states, quantum operations, and simulation results.The interface should be able to measure the accuracy of the simulation compared to what is expected in the real world.Existing work [22] on validation of simulation has used simulator platforms, such as the QISKit platform developed by IBM.The interface needs to validate the simulator against experimental data where possible.Because of a lack of available hardware, gathering heuristics to create a theoretical representation of the network's expected behavior will help validating results.
Finally, since work on quantum networks is continuously updating, simulators need to use a modular and extensible architecture.This allows users to easily incorporate new features, quantum algorithms, or simulation models to adapt the simulator to evolving research needs.Additionally, it also allows for validation tools to be incorporated into the simulation.Therefore, any standardized validation framework should also be modular to allow for new validation techniques to be added to the framework as they become available.
Understanding the output of a simulation
Simulations can be compared with known analytical solutions for specific quantum algorithms or network scenarios.For modeling entanglement distribution, validation methods include comparing the success rates, fidelity, and speed of entanglement generation with theoretical expectations and experimental data.
Another approach to validation is compare the resulting behavior of the simulation to an ideal solution.For this case, idealized simulations, where noise and errors are minimized or absent, can be used to verify the correctness of the implementation.Comparing results from a noise-free simulation with theoretical expectations helps ensure the accuracy of the simulator's fundamental quantum operations.Simulators like QuNetSim or SeQUeNCE, have assumed minimal to no errors in their models.
Quantum-Classical Hybrid simulators
Researchers have combined classical and quantum hybrid networks to develop full quantum networks [23].Here a validation framework also validates classical network capabilities and their impact on quantum networks.The interaction between classical and quantum networks includes simulating the interaction between classical and quantum information processing.Many existing quantum workloads and applications use a mix of pure quantum algorithms and classical programs.For example, "proper quantum" algorithms were still hybrid [24] use the Shor algorithm to model quantum parts but used classical processing for the data.
Quantum machine learning [25,26] uses classical machine learning enhanced or replaced by quantum algorithms [27,28].Hybrid approaches often involve classical pre-processing or post-processing steps alongside quantum algorithms to address machine learning tasks such as classification, clustering, and optimization.The preprocessing and optimization may take advantage of the cloud capabilities as an intermediate to distribute such large models developing Quantum Cloud Computing.
For Quantum Cloud Computing [29] to have the needed resources, quantum processors can be integrated into cloud computing environments.Researchers have explored how classical and quantum resources can be orchestrated to perform computations efficiently, taking advantage of the strengths of both.Companies such as IBM [30], Microsoft [31] and Google [32] have started offering cloud services that include access to quantum processors.These services allow users to run quantum algorithms and experiments on real quantum hardware through cloud platforms [33].The concept of hybrid quantum-classical cloud computing involves combining classical computing resources with quantum processing units.This approach is particularly useful for solving complex problems that leverage both classical and quantum algorithms.
Overview of Quantum Networking
Quantum networking is the infrastructure connecting one or more quantum physics devices such as for distributed quantum computing, sensors or setting up an entangled quantum network.As a means to advance science, quantum networking applications are exploring how to connect multiple observatories for super-resolution images of distant planets [34,7], or even link high-powered microscopes for unprecedented views of the micro-organisms [35], to help find more key insights in the problems being explored.
By utilizing quantum entanglement distribution, quantum networks are being used to develop secure communication channels for governments, banks, and more, with applications of Quantum Key Distributions (QKDs) [36,37,38].Qubits have two properties that enable these advances superposition and entanglement, that allows them to encode and carry information among two entangled qubits.However, qubits can be fragile and can loose their quantum states if there is loss or background noise.Various techniques can measure performance and stability of quantum networks such as state tomography [39], used to monitor the state of all qubits in a network, but is resource-intensive and becomes impractical for larger networks, or process tomography [40], which involves quantum operation in its fidelity and errors.Researchers have also developed the Bell state monitoring [41,42] method, that utilizes entangled Bell states, where changes in correlations between entangled qubits reveal network errors.This is less resource-intensive than full tomography but offers limited information.
Other developments in quantum repeaters and controllers are being used to amplify weaker signals, increase longer distances or perform qubit operations like rotations, measurements, and entanglement creation.
Table 1 shows some examples of existing quantum network testbed developments.Testbeds offer a real-world platform for experimenting with actual hardware and protocols.
Application of Quantum Networks
Some quantum applications, as seen in Table 2, include Quantum Key Distribution (QKD), sensing or quantum routing.Examples include QKD implementation in NS3 network simulator [43], clock synchronization accuracy [44] like GPS [45] and financial trading [46], or measuring magnetic fields or temperature over large distances with high [57] 2018 X GPU Acceleration + Quantum information processing SeQUeNCe [58,59] 2019 X X Open-Source + User-Friendly Interface ComNetsEmu [15] 2020 X In-network Artificial Intelligence + hybrid quantum network QuNetSim [14] 2021 X Scalability + Performance NetSquid [60] 2021 X X High-Performance Computing Integration QDNS [61] 2021 X Python based + Reusable network protocols QuISP [62] 2022 X X Error Correction + Fault Tolerance SimQN [63] 2023 X User-Defined Noise Models Cisco Qnetlab [64] 2024 X X Simulations in the cloud Table 3: Simulation toolkits for Quantum Networks (More details can be seen in Figure 2).
precision [47,48], or quantum-enhanced MRI [49].Quantum is also being explored for secure Cloud Computing [50,51] applications to benefit fields like materials science and drug discovery [52,53].
Overview of Quantum Networks simulators
Omnet++ [54], NetSim [55], and NS-3 [56] are well known network discrete-event simulators.These are a series of discrete event modeling toolkits used to simulate traffic flow, customer interactions in a call center, or packet flow in a network.The advantages of these are easier to implement and computationally efficient for large systems.However, these techniques are limited to discrete changes and may not capture continuous behavior accurately.
On the other hand, mathematics-driven simulators or Equation-Based Modeling (EBM) use mathematical equations to represent system dynamics.The advantages of such a simulation approach is that it allows for accurate representation of continuous processes and is flexible, but can be complex to build.For instance, capturing all the possible states and transitions of qubits in the network can be cumbersome and resource intensive.Hamiltonian-based models are another model that describes the energy structure of the network, good for understanding energy transfer, entanglement generation, and other quantum phenomena in the network.Most quantum simulators have been listed in Table 3.
QuISP
QuISP [62] is a quantum network simulator that uses the OMNET++ [54] framework as the base.OMNET++ is a C++ component-based framework used for building network simulators.In 2023, OMNET++ added several models to help users simulate more types of network and routing protocols such as routing protocol for low power and lossy networks.This uses Monte-Carlo simulation and supports error channels including Pauli channels and excitation/relaxation channels.Here, the evolution of the qubit is modeled as a Markov process, encoding flying qubits onto single photons to handle communication between nodes.This simulator enables users to experiment with different configurations under realistic and noisy conditions.As such, users can experiment with thousands of qubits in hundreds of nodes, enables more topology types and measure performance and behavior of the network.However, the simulation needs to be repeated to gain accurate information on the real state of the qubit and its fidelity.The full-density matrix simulation is not viable for 2G and 3G types of networks.QuISP tackles this issue by assuming that the desired quantum state is known, which is not always the case.
SeQUeNCe
SeQUeNCe [58,59] is a module-based simulator used to simulate new and upcoming quantum technologies.This simulator focuses more on customizability by having five distinct modules that users use to simulate hardware models, entanglement management protocols, resource management, network management, and applications.This structure is similar to the one used by NS3, a network simulator that is frequently used in research for communication networks.
The benefit of this simulator is that we can explore hybrid classical and quantum networks.They can simulate classical channels using quantum network protocols.They also offer the ability to use classical control software to enable rapid experimental progress.
However, the drawback of the simulator is that it assumes there is no loss and perfect reliability for the classical channel always exists.This means that the behavior is uncertain if the network ends up saturated or if there are any failures on the network.Additionally, they assume that the host node is the initiator of any request sent in the application module.
Essentially this means that having responses sent back to the initiator of a request may need to have some modifications to be done in the application module of the simulator.
QuNetSim
QuNetSim [14] is a Python-based simulator focused on developing an easy-to-use interface for simulating quantum networks at the network layer.This simulator can also be used to simulate new and existing link layer protocols.
The first benefit of QuNetSim is the ease of use of its interface.It comes with a pre-existing toolbox of quantum protocols that can be implemented in a few lines.This allows for anyone to start learning about quantum protocols and building their own.The second benefit is that it simulates real-time, unlike other simulators.This makes it well-suited to control laboratory hardware.
The drawback of this simulator is similar to the previous two simulators where it assumes links and the physical layer deliver error-free bit and qubit transmission capabilities, which is not the case especially as traffic grows between two points the network should start experiencing more loss and interference.
Use of Quantum Network simulator as part of Hybrid Network simulator (ComNetsEmu)
ComNetsEmu [15] is a network simulator that is compatible with the QuNetSim simulator.The ComNetsEmu has been built to support in-network Artificial Intelligence (AI).In recent years, an instance of the quantum network simulator QuNetSim has been merged into the link layer of the classical network emulator ComNetsEmu to create an initial hybrid network simulator [23].The resulting simulator was used as a way to describe the structure of the full stack of a hybrid quantum-classical network.
Netsquid
Netsquid [60] is a discrete-event-based platform for simulating all aspects of quantum networks.It is widely used across the research community, especially for research in quantum networking and applications.It offers a realistic platform that enables users to collect realistic data on how well their project runs on a quantum network.
This simulator allows for using large amounts of threads that reduce the runtime linearly with the number of processing cores available.The authors assume that there is sufficient memory available and reiterate that there is a need for a tightly integrated classical control plane with the quantum network.Compared to other simulators, NetSquid also models noise measured during data transfer in the network.
SimQN
SimQN is a discrete-event-based network simulation platform for quantum networks.It is designed to be a functional and easy-to-use tool similar to NS3 for classical networks.It provides researchers with a platform to experiment and simulate quantum networks without needing expensive hardware or waiting for new technology to become available.It aims to address the lack of validation methods for existing quantum network simulations.As explained by Chen et al. [63], SimQN provides an average of 8.02 times performance improvement over NetSquid.Another benefit of this simulator is that it provides a modular design that allows for easy customization and extension.This is a benefit since quantum is an evolving field that consistently has new hardware and protocols being developed.As such SimQN enables rapid prototyping and testing of new quantum network protocols and is publicly available [65].
QDNS
QDNS [61], Quantum Dynamic Network Simulator, is a theoretical framework for simulating the behavior of qubits.Similar to SimQN, QDNS is publically available on [66].It is a Python-based simulator which makes it user-friendly but reduces the resulting performance of the simulator compared to other simulators.It also provides reusable network protocols and utilities which reduces development time and effort for researchers.
Cisco's Qnetlab
This is a software development kit created by Cisco Research [64] to simplify the design and execution of simulations for quantum networks.It provides a platform for building and running simulations in the cloud, as well as a protocol builder for designing quantum network protocols.
Squanch
Squanch stands for Simulator for Quantum Networks and CHannels [57].This is an open-source Python library for simulating quantum networks, focusing on providing tools for developers to design and run simulations, not on building actual quantum networks.
Squanch is specifically designed for simulating distributed quantum information processing, making it particularly efficient for modeling complex quantum networks that involve multiple nodes and communication channels.By running simulations with different parameters, researchers can fine-tune existing protocols to improve their performance and reliability.Additionally, Squanch can be used to explore the potential of novel network designs and assess their feasibility before committing resources to building them in hardware.Finally, the library leverages the power of multiple processors to run simulations faster, especially for large-scale networks.
Unlike real-world quantum systems, Squanch simulations are based on models and approximations.These models might not capture all the complexities of real-world systems, leading to potential inaccuracies in the simulation results.This is especially true for simulating large-scale networks or complex noise models.While simulations can provide valuable insights, there's still a gap between simulated behavior and the actual performance of quantum hardware.Factors like hardware limitations, control errors, and decoherence can significantly affect the practical implementation of protocols designed based solely on simulations.Finally, although Squanch utilizes parallelization, simulating extremely large or intricate networks can still become computationally expensive and time-consuming.This can limit its applicability for studying certain types of large-scale quantum systems.
Background and Discussions
Building and experimenting with quantum networks can be expensive and time-consuming.Simulations allow researchers to test and refine their designs virtually, exploring different architectures, protocols, and parameters to optimize network performance before committing to physical implementations, crucial for developing robust and reliable quantum communication and computing systems.
Model Quantum Devices
Quantum devices are devices that exploit the principles of quantum mechanics to perform computations.Examples include superconducting qubits [67,68], trapped ion qubits [69], and photonic qubits [70,71,72] used in quantum computers.Superconducting qubits are used in superconducting circuits cooled to near absolute zero to encode quantum information.Trapped ion qubits are used individual ions held in place by electromagnetic fields to represent quantum information.Photonic Qubits use photons (particles of light) to encode quantum information.
Model Quantum Protocols
There are various techniques to model quantum protocols including Stochastic Simulation [73,74,75] and Tensor Network Methods [76,77].Stochastic simulation employs a random sampling approach to simulate the evolution of the quantum state during a protocol.This technique is efficient for analyzing protocols with limited resources.However, it can be statistically noisy such that this approach might not capture the full complexity of the system.Another commonly used approach is the Tensor Network Method, which is a technique that represents the quantum state by decomposing it into a network of tensors.This approach offers an efficient way to model systems with entangled qubits, especially for specific types of entanglement structures.These techniques can become computationally expensive for more general scenarios.
Model Quantum Repeaters
When developing repeaters, it is important to understand that the type of links used would impact the qubit generation technique used by the network.Researchers also need to understand when the resource allocation policy should be triggered and what factors seem to be crucial in the development of a quantum network.
First, the placement of repeaters has a direct impact on the loss, similar to the placement of the GnB nodes (relay antennas) in a wireless or 5G network.If the relay antennas are too far apart, then the signal may suffer from more interference since it needs to travel farther.In quantum networks, information degrades over distance due to decoherence.This means that the distance between repeaters should be less than the decoherence length of the chosen channel (fiber optic cable, free space, etc).
Additionally, not all repeaters are built the same way.The quantum memory type and lifetime vary between repeater technologies.This means that some repeaters can transmit signals across a wider distance than others.The entanglement generation and manipulation capabilities and the maintenance also vary between different repeater technologies.A network architect needs to understand the capabilities of each type of repeater used in the network before determining where to place them.This is where simulators can become useful since they give the user the ability to quickly try different repeater technologies.They can then quantify each topology and select the best one for the network's purpose.
One approach to model repeaters is using a Heuristic or Analytical model.These algorithms use simplifying assumptions to quickly find possible repeater placements that can satisfy minimum requirements like connectivity and cost.One can expand on this to incorporate detailed channel characteristics, technology specifications, and network topology constraints to optimize placement for factors like fidelity, throughput, and cost.However, while those models can be easy to implement, they struggle when modeling complex systems.To tackle these issues there are simulation tools in which quantum repeater networks can be simulated to evaluate different placement scenarios and their performance under various conditions.
Complexity of Modeling Quantum Networks
Simulating entire quantum networks at the lower levels of individual qubits quickly becomes computationally intractable as the network grows [78].Abstraction levels allow researchers to focus on the essential features of the network for a specific task [79].Additionally, abstraction levels provide a framework for designing and developing quantum protocols and algorithms without worrying about the intricate workings of the underlying physical qubits.
For example, modelling a long-distance quantum network can reveal the error rate (complexity [80,81]) increases rapidly with distance.Adding a sophisticated error correction protocol or exploring alternative network architectures with built-in redundancy for enhanced resilience can help develop better models.Complexity models can be used to simulate how errors propagate through the network and assess the effectiveness of different error correction protocols.
The resulting complexity analysis helps design more robust networks with improved fidelity (accuracy) in transmitting quantum information.
Compuational Resources Needed.Simulating the dynamic behavior of quantum networks, where nodes can be added or removed, and connections can change over time, is also of interest.This includes nodes that become unresponsive because of some fault, allowing quantum network simulators to become more realistic.Understanding how the performance of the network topology changes when a node is unavailable can help researchers understand how their protocol and network topology work in the real world.
Optimizing the use of quantum resources, such as entanglement generation and distribution, is also a key challenge.At the core of quantum networks, entanglement generation and distribution are used to transmit data from one node to another.Depending on the interaction between qubits and the outside world the resulting qubit value by a node may change and understanding how that change happens would lead simulators to become more realistic tools for researchers.
Benchmarking Simulations.These include entanglement generation success rates [82,83], fidelity of entanglement [84,85], entanglement distribution speed [86], or scalability (ex: running millions of agents at the same time with massive data at HPC speed).Other metrics involve the need to integrate with MPI to run on HPC system to increase parallelism and avoid bottlenecks.With these available benchmarks, there is a need to create a tool that can give an overall view of the performance of their network topology and protocols.
Often, benchmarks have focused on measuring fidelity and the resource usage.Fidelity is a measure of how well the generated entangled states match the ideal entangled states and the benchmarks assess the fidelity of entanglement distribution, and the quality of the generated entangled pairs.Additionally, evaluating the time required to establish entanglement between nodes also helps assess the efficiency of entanglement generation processes.
Other Approaches to Qubit Behavior Simulation
There are several methods used to simulate qubits such as Stochastic Wavefunction [87], Tensor Network [88], and Monte-Carlo [89].Stochastic wavefunction methods, like the Quantum Trajectory Approach, involve random sampling of quantum trajectories to approximate the evolution of a quantum system.These methods can be more computationally efficient than exact simulations for certain scenarios.Tensor network methods, including the Matrix Product State [90] (MPS) and the Tensor Network State [91] (TNS) representations, are used for simulating the state of a quantum system.These methods offer a more efficient representation of quantum states, especially for systems with entanglement.And, Monte-Carlo methods are employed in quantum Monte-Carlo simulations to estimate physical quantities related to quantum systems.Variational Monte-Carlo and Diffusion Monte-Carlo are examples of techniques used for qubit simulations.Since currently there is still development happening on different generation methods for qubits, quantum network simulators should at least offer all three approaches so that researchers can explore the effect of all three methods on their new protocol.
Understanding Qubit behavior
In this section, we focus on developing an analytical model that can be used to model the evolution of the density matrix of a quantum system, such as a qubit, going through a quantum communication channel.We start with qubit transmission since it is the base usage of networks and qubits are quantum systems that carry the quantum information from one node to another in a quantum network.A single qubit state can be expressed by using the Dirac notation [92,93].An example representation of a qubit is represented in Equation 1.
|Ψ⟩ = α |0⟩ + β |1⟩(1)
Researchers have used the the Bloch equation [94,95,96], as described in Equation 2, to model qubit behavior.This equation describes the evolution of the Bloch vector, which is a three-dimensional vector that represents the state of a qubit.It uses differential equations that takes into account the Hamiltonian of the qubit system, which is the operator that describes the energy of the system, which includes 2 or more qubits.It can also be used to describe other aspects linked to qubit behaviors such as precession and relaxation.Precession is the rotation of the qubit state around the Bloch sphere at a frequency that is proportional to the qubit transition frequencies.Relaxation is the decay of the qubit state to its equilibrium value over time due to interactions with the environment.
dM x/dt = ωyM y − ωzM z dM y/dt = −ωxM x + ωzM z dM z/dt = −ωxM x − ωyM y − (M z − M 0)/T 1 (2)
M x, M y, and M z are the components of the Bloch vector on the Bloch sphere.ωx, ωy, and ωz are the frequencies of the qubit transitions in the x, y, and z directions, respectively.M0 is the equilibrium magnetization, which is typically zero for qubits.T1 is the longitudinal relaxation time constant, which is the time it takes for the longitudinal magnetization to relax back to its equilibrium value after it has been perturbed.
Overall, Bloch equations have been used to model qubit behaviors on quantum communication channels [97,98,99].However, they are not a fully accurate representation of qubit dynamics [100,101].This is due to their classical nature, limited scope to two-level systems [102,103], and lack of consideration for other quantum aspects such as decoherence [104].For more accurate modeling, more sophisticated techniques such as the master equation are typically used.Therefore, the master equation can be used to determine the evolution of the density matrix of a quantum system.
The master equation for a qubit in a quantum communication channel is given by Equation 3, where ρ is the density matrix of the qubit, L is the Hamiltonian of the qubit system, Γ is the decoherence rate, and ρeq is the equilibrium density matrix of the qubit.By using this equation, we can directly model the impact of different types of channel parameters on the resulting density matrix of the qubit.Γ and L can be used to experiment with different rates of noise on a quantum system.
dρ/dt = −iLρ − Γ(ρ − ρeq)(3)
The decoherence rate value Γ depends on the type of noise that the qubit is subject to and the properties of the environment.The decoherence rate can be calculated from the longitudinal relaxation time constant (T1) and the transverse relaxation time constant (T2), as described by Equation 4. By looking at this equation and the Bloch equation we can see that the Bloch equation is missing the decoherence value when calculating the updated state of the qubit.
Γ = 1/(2 * T 1) + 1/(T 2 * π)(4)
The Hamiltonian is written as a formula showing the interaction between the energy of 2 qubits described as L = L 0 + L int .L 0 is the free Hamiltonian, which describes the energy of the qubits in the absence of any interactions.On the other hand, L int is the interaction Hamiltonian, which describes the energy of the interactions between the qubits.Both L 0 and L int are described in Equation 5.
L 0 = (1/2) * ∆ω * σ z L int = J * σ i σ j(5)
In the equation, the variables include different components of qubits.∆ω is the qubit transition frequency.σ z is the Pauli Z operator [105,106].J is the coupling constant between the qubits [107,108].There exist multiple models that can be used to determine the J coupling value, such as Ising Model or XY Model.It depends on the type of interaction that is being modeled.For example, the XY model seems to depend heavily on the temperature of the system while the Ising model the intrinsic dimension is independent of the real-space topology [109].Therefore, an interface that uses the equation set needs to have the ability to swap the coupling constant depending on the need of the user and the experiment.Finally, σ i and σ j are the Pauli operators for the ith and jth qubits, respectively.The Pauli operators are three operators: the X, Y and Z operators.The Pauli operators [110] are denoted using the formulas described in equation 6. Because, even the smallest components of these equations can be written as vector math, using the existing literature, we can build a model that can be used by other researchers to validate new development in quantum network simulators.
X = |0 >< 1| + |1 >< 0| = 0 1 1 0 Y = −i|0 >< 1| + i|1 >< 0| = 0 −i i 0 Z = |0 >< 0| − |1 >< 1| = 1 0 0 −1(6)
Now that the behavior of a qubit is shown using vector math, it is important to acknowledge that such an approach does not scale well.The number of variables and equations involved in analytical models grows exponentially with the number of qubits or network components.This can quickly render them impractical for simulating realistic quantum networks.This means that validating a simulation of a full network may need other validation techniques such as using Monte-Carlo simulations, which enable us to run the simulation repeatedly under different conditions.Because of the scaling problem, translating analytical models into efficient and accurate simulation code can also be a complex task, which can lead to the potential introduction of errors or numerical instabilities.
Additionally, assumptions taken by the developers of the analytical models play a crucial part in the outcome of the validation.Verifying these assumptions in real-world quantum networks can be challenging, leading to uncertainties in the model's accuracy.Additionally, analytical models often make simplifying assumptions, such as perfect qubits, noiseless operations, and ideal channels.These assumptions may not accurately reflect the behavior of real-world quantum networks, which are inherently susceptible to noise, imperfections, and environmental influences.As a result, analytical models may fail to capture the full complexity and nuances of physical quantum systems, potentially leading to inaccurate or misleading simulation results.
Analytical Benchmarking
Dealing with multiple dimensional vector data, a first approach for validation is Euclidean distance [111].This metric lets users visualize how closely the simulated qubit density matrix matches the expected one.A small distance indicates that the simulated channel behaves as expected in a real quantum network running the same workload.
However, for a deeper understanding of the discrepancies between the two density matrices, the Earth Mover's algorithm, can be used for comparing 2D data, needed to transform one distribution into the other.By combining Euclidean distance and the Earth Mover's value, users can gain a comprehensive picture of how well the simulation replicates reality.A small distance and a low 'dirt' value would strongly validate the resulting qubit value.
Besides Euclidean distance and Earth Mover's distance, there are several other comparison metrics for 3D vector data.These comparison metrics include distance-based metrics, distribution-based metrics, and directional metrics.We want to use a combination of all three types of metrics to validate the simulated qubit behavior.Similar to Euclidean, the Manhattan distance allows distance metric calculated over the sum of absolute differences instead of squares, emphasizing outliers.Outliers are important to identifying any isolated discrepancies in the simulated results.Using the Root Mean Square Distance between the simulated qubit density metric and the theoretical density metric, it records the impact of larger errors.
Another benchmark is to understand how the simulation modeled the distribution of the density matrix.The Kullback-Leibler divergence [112] (KL divergence) measures how much information is lost when describing one distribution with another.Jensen-Shannon divergence [113], is another distribution-based metric, similar to KL divergence but symmetric based, useful for comparing two distributions simultaneously.This metric allows users to evaluate how well the simulation models the interactions between 2 qubits.Also one can combine the result of Jensen-Shannon divergence with Bhattacharya distance [114,115] to see how much overlap the simulated matrix has with the resulting theoretical matrix.The Bhattacharya distance measures the overlap between two probability distributions.
Finally, comparing the direction of both the simulated density matrix and the resulting density matrix one can compare the angle between both vectors.This measures the rotation needed to align one vector with the other.The 'size' of the rotation needs to align one set of vectors with the other, we can use the Rotation Matrix Frobenius norm.
Conclusion and Future Directions of Research
This survey identifies a need for a standardized platform to validate existing quantum simulators.By using existing theoretical work for a validation interface, one can generate values of the density matrix that would be expected depending on certain network conditions.Developing a user-friendly interface that can be used by the research community, can help users validate the result of simulators.
Further, this can also be used to study the interaction between classical and quantum networks.Because qubits carry data in quantum networks it is important to understand how the interactions impact the qubit values.The validation interface should evolve to include the validation techniques for the behavior of hybrid networks expected in the real world.
We also discussed using analytical models such as modeling a qubit behavior, quantum bnchmarking, or classical shadow optimization to verify quantum network simulators.For quantum benchmarking, we propose to build a library of benchmarking workloads and protocols that can be used to probe the capabilities and limitations of quantum devices and simulators.These benchmarks, like Bell state preparation and tomography, provide a reference point for evaluating the accuracy and fidelity of simulations.For the case of classical shadow optimization, we can use a classical optimization algorithm that mimics the behavior of a quantum algorithm.This algorithm can then provide a classical approximation of the quantum simulation results.Comparing the two sets of results can highlight potential errors or limitations in the simulator.
Further explorations of formal verification testing and code review can be performed, with sensitivity analysis, to include noise injection and statistical analysis to understand how the simulation is performing.Simulating the effects of different types of noise, such as decoherence and state preparation errors, is crucial for assessing the robustness and accuracy of quantum network simulations.It can help researchers identify sensitive areas and potential sources of error in the simulation.Additionally, performing a parameter sweep by systematically varying key parameters of the quantum network, such as coupling strengths or interaction times, allows researchers to study the behavior of the simulated system across a wider range of conditions.This can reveal unexpected dependencies or edge cases that require further validation.
Finally, using existing validation techniques such as Monte-Carlo simulations can help reveal inconsistencies in the outcome of the simulation.Running the simulation multiple times with different initial conditions or random noise variations helps to quantify the statistical uncertainty and variability of the results.This provides a more complete picture of the simulated system's behavior and avoids concluding single realizations.Additionally, statistical tests can be used to formally compare the simulated outcomes with a particular hypothesis or reference data.This allows for a rigorous assessment of the validity and significance of the simulation results.
Figure 2 :
2
Figure 2: Quantum network simulator flowchart.
Table 1 :
1
List of quantum testbeds being developed across the world, to name a few.
,
Table 2 :
2
High level examples of Quantum Applications.
QN Applications over the last 5 yearsApplicationDescriptionQuantum Key DistributionPhotons used to securely share encryption keysQuantum sensingMeasure magnetic fields over large distances with highprecision for example [18]Secure Cloud ComputingSecure access to quantum computers in the cloudDistributed Quantum ComputationDistributed quantum processing across geographically dis-tributed quantum computersQuantum Network simulators comparisonSimulators nameyearSmall topologyLarge topologyFocusSquanch
AcknowledgementsDuring the preparation of this work the author(s) used Google Bard in order to improve grammar and flow of the text in the paper, and to supplement background research.After using this tool, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.This work was supported by the U.S. DOE Office of Science, Office of Advanced Scientific Computing Research, under award 66150: "CENATE -Center for Advanced Architecture Evaluation" project and the DOE ASCR Early Career Grant "Large Scale Deep Learning for Intelligent Networks" award ERKJ435 hosted at Oak Ridge National Laboratory.The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy under contract DE-AC05-76RL01830.This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE).The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes.DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (https://www.energy.gov/downloads/doe-public-access-plan).
Theoretical framework for quantum networks. Giulio Chiribella, Giacomo Mauro D'ariano, Paolo Perinotti, Physical Review A. 802223392009
Towards real-world quantum networks: a review. Shi-Hai Wei, Bo Jing, Xue-Ying Zhang, Jin-Yu Liao, Chen-Zhi Yuan, Bo-Yu Fan, Chen Lyu, Dian-Li Zhou, You Wang, Guang-Wei Deng, Laser & Photonics Reviews. 16321002192022
Towards large-scale quantum networks. Wojciech Kozlowski, Stephanie Wehner, Proceedings of the sixth annual ACM international conference on nanoscale computing and communication. the sixth annual ACM international conference on nanoscale computing and communication2019
Long-term cybersecurity applications enabled by quantum networks. Nicholas A Peters, Muneer Alshowkan, Joseph C Chapman, Raphael C Pooser, S V Nageswara, Raymond T Rao, Newell, 42023
Quantum sensing with squeezed light. B J Lawrie, P D Lett, A M Marino, R C Pooser, ACS Photonics. 662019
Quantum error correction for communication with linear optics. Samuel L Braunstein, Nature. 39466881998
Advances in space quantum communications. Jasminder S Sidhu, K Siddarth, Mustafa Joshi, Thomas Gündogan, David Brougham, Luca Lowndes, Markus Mazzarella, Sonali Krutzik, Daniele Mohapatra, Giuseppe Dequal, Vallone, IET Quantum Communication. 242021
Optimal architectures for long distance quantum communication. Sreraman Muralidharan, Linshu Li, Jungsang Kim, Norbert Lütkenhaus, Liang Mikhail D Lukin, Jiang, Scientific reports. 61204632016
. Muneer Alshowkan, S V Nageswara, Joseph C Rao, Brian P Chapman, Philip G Williams, Raphael C Evans, Joseph M Pooser, Nicholas A Lukens, Peters, Lessons Learned on the Interface between Quantum and Conventional Networking. 112021
Throughput Measurements and Capacity Estimates for Quantum Connections. S V Nageswara, Muneer Rao, Joseph C Alshowkan, Nicholas A Chapman, Joseph M Peters, Lukens, 52023
Quantum repeaters: From quantum networks to the quantum internet. Koji Azuma, Sophia E Economou, David Elkouss, Paul Hilaire, Liang Jiang, Hoi-Kwong Lo, Ilan Tzitrin, Reviews of Modern Physics. 954450062023
Quantum internet-applications, functionalities, enabling technologies, challenges, and research directions. Amoldeep Singh, Kapal Dev, Harun Siljak, Hem Dutt Joshi, Maurizio Magarini, IEEE Communications Surveys & Tutorials. 2342021
Protecting quantum states against loss. Quantum. Benjamin Desef, Martin B Plenio, 2021. 2021
Qunetsim: A software framework for quantum networks. Stephen Diadamo, Janis Nötzel, Benjamin Zanger, Mehmet Mert, Beşe , IEEE Transactions on Quantum Engineering. 22021
Computing in Communication Networks: From Theory to Practice. Fabrizio Frank Hp Fitzek, Patrick Granelli, Seeling, 2020Academic Press
Enhancing distributed functional monitoring with quantum protocols. Michele Amoretti, Mattia Pizzoni, Stefano Carretta, Quantum Information Processing. 201918371
Control plane and virtualized development environment for softwarized quantum networks. S Nageswara, Travis S Rao, Humble, 2018Oak Ridge, TN (United States)Oak Ridge National Lab.(ORNL)Technical report
Quantum network engineering in the nisq age: Principles, missions, and challenges. Uman Khalid, Saw Nang Junaid Ur Rehman, Haejoon Paing, Trung Q Jung, Hyundong Duong, Shin, IEEE Network. 2023
Programmable multinode quantum network design and simulation. Ronald J Venkat R Dasari, Ryan Sadlier, Brian P Prout, Travis S Williams, Humble, Quantum Information and Computation IX. SPIE20169873
Simulation of a dynamic, ruleset-based quantum network. Takaaki Matsuo, arXiv:1908.107582019arXiv preprint
Fighting noise with noise in realistic quantum teleportation. Raphael Fortes, Gustavo Rigolin, Physical Review A. 921123382015
Ieva Čepaitė, arXiv:2212.12953Simulation of networked quantum computing on encrypted data. 2022arXiv preprint
Integrating quantum simulation for quantum-enhanced classical network emulation. Stephen Diadamo, Janis Nötzel, Simon Sekavčnik, Riccardo Bassoli, Roberto Ferrara, Christian Deppe, Frank Hp Fitzek, Holger Boche, IEEE Communications Letters. 25122021
Hybrid quantum applications need two orchestrations in superposition: a software architecture perspective. Benjamin Weder, Johanna Barzen, Frank Leymann, Michael Zimmermann, 2021 IEEE International Conference on Web Services (ICWS). IEEE2021
Quantum machine learning. Jacob Biamonte, Peter Wittek, Nicola Pancotti, Patrick Rebentrost, Nathan Wiebe, Seth Lloyd, Nature. 54976712017
Recent advances in quantum machine learning. Yao Zhang, Qiang Ni, Quantum Engineering. 20202e34
Quantum machine learning: a classical perspective. Carlo Ciliberto, Mark Herbster, Alessandro Davide Ialongo, Massimiliano Pontil, Andrea Rocchetto, Simone Severini, Leonard Wossnig, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 474201705512209. 2018
Quantum machine learning in feature hilbert spaces. Maria Schuld, Nathan Killoran, Physical review letters. 1224405042019
The quantum way of cloud computing. Harpreet Singh, Abha Sachdev, 2014 International Conference on Reliability Optimization and Information Technology (ICROIT). Ieee2014
Ibm's quantum cloud computer goes commercial. Davide Castelvecchi, Nature. 54376442017
Azure quantum. Introducing Microsoft Quantum Computing for Developers: Using the Quantum Development Kit and Q#. Johnny Hooyberghs, Johnny Hooyberghs, 2022
Cloud computing in the quantum era. Mustafa Kaiiali, Sakir Sezer, Ayesha Khalid, 2019 IEEE Conference on Communications and Network Security (CNS). IEEE2019
Towards cloud agnostic quantum-classical hybrid computing. Hai Luong, 2023
Optical interferometry with quantum networks. Johannes Emil T Khabiboulline, Kristiaan Borregaard, Mikhail D De Greve, Lukin, Physical review letters. 1237705042019
Telecom-band quantum dot technologies for long-distance quantum networks. Ying Yu, Shunfa Liu, Chang-Min Lee, Peter Michler, Stephan Reitzenstein, Kartik Srinivasan, Edo Waks, Jin Liu, Nature Nanotechnology. 18122023
Norbert Lütkenhaus, and Momtchil Peev. The security of practical quantum key distribution. Helle Valerio Scarani, Nicolas J Bechmann-Pasquinucci, Miloslav Cerf, Dušek, Reviews of modern physics. 81313012009
Experimental quantum key distribution certified by bell's theorem. Peter David P Nadlinger, Drmota, C Bethan, Gabriel Nichol, Dougal Araneda, Raghavendra Main, David M Srinivas, Christopher J Lucas, Kirill Ballance, Ey-Z Ivanov, Tan, Nature. 60779202022
Continuous-variable quantum key distribution system: Past, present, and future. Yichen Zhang, Yiming Bian, Zhengyu Li, Song Yu, Hong Guo, Applied Physics Reviews. 1112024
Efficient quantum state tomography. Marcus Cramer, Martin B Plenio, Steven T Flammia, Rolando Somma, David Gross, Stephen D Bartlett, Olivier Landon-Cardinal, David Poulin, Yi-Kai Liu, Nature communications. 111492010
Quantum-process tomography: Resource analysis of different strategies. Masoud Mohseni, Ali T Rezakhani, Daniel A Lidar, Physical Review A. 773323222008
Practical quantum private query based on bell state. Tao Zheng, Shibin Zhang, Xiang Gao, Yan Chang, Modern Physics Letters A. 342419501962019
Bell states of atoms with ultralong lifetimes and their tomographic state analysis. Cf Roos, Lancaster, Riebe, Häffner, Hänsel, Gulde, Becher, F Eschner, Schmidt-Kaler, Blatt, Physical review letters. 92222204022004
Qkdnetsim+: Improvement of the quantum network simulator for ns-3. SoftwareX. David Soler, Iván Cillero, Carlos Dafonte, Manuel Fernández-Veiga, Ana Fernández Vilas, Francisco J Nóvoa, 202426101685
Clock synchronization with correlated photons. Christopher Spiess, Sebastian Töpfer, Sakshi Sharma, Andrej Kržič, Meritxell Cabrejo-Ponce, Uday Chandrashekara, Nico Lennart Döll, Daniel Rieländer, Fabian Steinlechner, Physical Review Applied. 195540822023
Synchronizing clocks via satellites using entangled photons: Effect of relative velocity on precision. Stav Haldar, Ivan Agullo, James E Troupe, Physical Review A. 1086626132023
Quantum time synchronization for satellite networks. Osel Swaraj Shekhar Nande, Marius Lhamo, Riccardo Paul, Bassoli, Frank, Fitzek, 2023 IEEE Aerospace Conference. IEEE2023
Quantum sensing of magnetic fields with molecular color centers. Daniel W Kathleen R Mullin, Danna E Laorenza, James M Freedman, Rondinelli, Physical Review Research. 54L0420232023
Quantum-based magnetic field sensors for biosensing. Bo Bao, Yu Hua, Ridong Wang, Dachao Li, Advanced Quantum Technologies. 202362200146
Quantum-enhanced mri sensitivity: Dissolution-dynamic nuclear and parahydrogen-induced polarization. Xiai Wang, Highlights in Science, Engineering and Technology. 202338
Iot-enabled secure and scalable cloud architecture for multi-user systems: A hybrid post-quantum cryptographic and blockchain based approach towards a trustworthy cloud computing. Reyazur Rashid Irshad, Shahid Hussain, Ihtisham Hussain, Jamal Abdul Nasir, Asim Zeb, M Khaled, Ahmed Alalayah, Adil Abdu Alattab, Ibrahim M Yousif, Alwayle, 2023IEEE Access
Quantum cryptography based cloud security model (qc-csm) for ensuring cloud data security in storage and accessing. Sundar, Sasikumar, Jayakumar, Nagarajan, Karthick, Multimedia Tools and Applications. 202382
Recent advances in quantum computing for drug discovery and development. Gautam Kumar, Sahil Yadav, Aniruddha Mukherjee, Vikas Hassija, Mohsen Guizani, 2024IEEE Access
Secure quantum computing for healthcare sector: A short analysis. Srikanth Pulipeti, Adarsh Kumar, Security and Privacy. 65e2932023
Andras Varga, Omnet++, Modeling and tools for network simulation. Springer2010
Netsim: Java™-based simulation for the world wide web. Tamie L Veith, John E Kobza, Koelling Patrick, Computers & operations research. 2661999
Ns-3: Network simulator 3. Gustavo Carneiro, UTM lab meeting April. 201020
A distributed simulation framework for quantum networks and channels. Ben Bartlett, arXiv:1808.070472018arXiv preprint
Sequence: a customizable discrete-event simulator of quantum networks. Xiaoliang Wu, Alexander Kolar, Joaquin Chung, Dong Jin, Tian Zhong, Rajkumar Kettimuthu, Martin Suchara, Quantum Science and Technology. 64450272021
Sequence simulator of quantum network communication. Kettimuthu, 2019
Netsquid, a network simulator for quantum information using discrete events. Tim Coopmans, Robert Knegjens, Axel Dahlberg, David Maier, Loek Nijsten, Julio De Oliveira Filho, Martijn Papendrecht, Julian Rabbie, Filip Rozpedek, Matthew Skrzypczyk, Communications Physics. 411642021
Qdns: Quantum dynamic network simulator based on event driving. Osman Semi, Ceylan , Ihsan Yilmaz, 2021 International Conference on Information Security and Cryptology (ISCTURKEY). IEEE2021
Quisp: a quantum internet simulation package. Ryosuke Satoh, Michal Hajdušek, Naphan Benchasattabuse, Shota Nagayama, Kentaro Teramoto, Takaaki Matsuo, Sara Ayman Metwalli, Poramet Pathumsoot, Takahiko Satoh, Shigeya Suzuki, 2022 IEEE International Conference on Quantum Computing and Engineering (QCE). IEEE2022
Simqn: A network-layer simulator for the quantum network investigation. Lutong Chen, Kaiping Xue, Jian Li, Nenghai Yu, Ruidong Li, Qibin Sun, Jun Lu, IEEE Network. 2023
Stephen Diadamo, The quantum network development kit. 2024
. Lutong Chen, Jian Li, Kaiping Xue, Nenghai Yu, Ruidong Li, Qibin Sun, Jun Lu, Simqn, 2022
. Osman Semi, Ceylan , Ihsan Yilmaz,
Andreas Michel H Devoret, John M Wallraff, Martinis, cond-mat/0411174Superconducting qubits: A short review. 2004arXiv preprint
Superconducting qubits: Current state of play. Morten Kjaergaard, Mollie E Schwartz, Jochen Braumüller, Philip Krantz, I-J Joel, Simon Wang, William D Gustavsson, Oliver, Annual Review of Condensed Matter Physics. 112020
Trapped-ion quantum computing: Progress and challenges. Colin D Bruzewicz, John Chiaverini, Robert Mcconnell, Jeremy M Sage, Applied Physics Reviews. 622019
Photonic quantum technologies. L Jeremy, Akira O'brien, Jelena Furusawa, Vučković, Nature Photonics. 3122009
Photonic qubits, qutrits and ququads accurately prepared and delivered on demand. Jerome Peter Br Nisbet-Jones, Annemarie Dilley, Oliver Holleczek, Axel Barter, Kuhn, New Journal of Physics. 155530072013
On-demand storage of photonic qubits at telecom wavelengths. Duan-Cheng Liu, Pei-Yun Li, Tian-Xiang Zhu, Liang Zheng, Jian-Yin Huang, Zong-Quan Zhou, Chuan-Feng Li, Guang-Can Guo, Physical Review Letters. 129212105012022
Quantum stochastic optimization. Bruno Apolloni, Diego De Carvalho, Falco, Stochastic Processes and their Applications. 198933
Matrix product states for quantum stochastic modeling. Chengran Yang, Felix C Binder, Varun Narasimhachar, Mile Gu, Physical Review Letters. 121262606022018
Implementing quantum dimensionality reduction for non-markovian stochastic simulation. Kang-Da Wu, Chengran Yang, Ren-Dong He, Mile Gu, Guo-Yong Xiang, Chuan-Feng Li, Guang-Can Guo, Thomas J Elliott, Nature Communications. 14126242023
Tensor-network-assisted variational quantum algorithm. Junxiang Huang, Wenhao He, Yukun Zhang, Yusen Wu, Bujiao Wu, Xiao Yuan, Physical Review A. 1085524072023
Tensor network algorithms: A route map. Carmen Mari, Bañuls, Annual Review of Condensed Matter Physics. 142023
Simulation of quantum circuits using the big-batch tensor network method. Feng Pan, Pan Zhang, Physical Review Letters. 1283305012022
Quantum internet: A vision for the road ahead. Stephanie Wehner, David Elkouss, Ronald Hanson, Science. 362641292882018
Structural complexity of quantum networks. Michael Siomau, AIP Conference Proceedings. AIP Publishing20161742
Quantum network coding. Masahito Hayashi, Kazuo Iwama, Harumichi Nishimura, Rudy Raymond, Shigeru Yamashita, Annual Symposium on Theoretical Aspects of Computer Science. Springer2007
Statistical analysis of quantum-entangled-network generation. E Scott, Pieter Vinay, Kok, Physical Review A. 994423132019
Entanglement generation in a quantum network at distance-independent rate. npj Quantum Information. Ashlesha Patil, Mihir Pant, Dirk Englund, Don Towsley, Saikat Guha, 2022851
Fidelity-guaranteed entanglement routing in quantum networks. Jian Li, Mingjun Wang, Kaiping Xue, Ruidong Li, Nenghai Yu, Qibin Sun, Jun Lu, IEEE Transactions on Communications. 70102022
Geometry of faithful entanglement. Otfried Gühne, Yuanyuan Mao, Xiao-Dong Yu, Physical Review Letters. 126141405032021
Four-dimensional entanglement distribution over 100 km. Takuya Ikuta, Hiroki Takesue, Scientific reports. 818172018
Stochastic wave-function method for nonmarkovian quantum master equations. Heinz-Peter Breuer, Bernd Kappler, Francesco Petruccione, Physical Review A. 59216331999
Introduction to tensor network methods. Simone Montangero, Evenson Montangero, Evenson , 2018Springer
Monte carlo methods. John Hammersley, 2013Springer Science & Business Media
David Perez-Garcia, Frank Verstraete, Michael M Wolf, Ignacio Cirac, quant-ph/0608197Matrix product state representations. 2006arXiv preprint
Tensor network states and geometry. Glen Evenbly, Guifré Vidal, Journal of Statistical Physics. 1452011
Dirac notation. Roderich Tumulka, Compendium of Quantum Physics. Springer2009
D Jack, Jack D Hidary, Hidary, Dirac notation. Quantum Computing: An Applied Approach. 2021
On the behaviour of pulsed qubits and their application to feed forward networks. Moraes Matheus, Antonio Hammes, Robles-Kelly, arXiv:2302.104672023arXiv preprint
Two-qubit bloch sphere. Chu-Ryang Wie, Physics. 232020
Spectrum of qubit oscillations from generalized bloch equations. Rusko Ruskov, Alexander N Korotkov, Physical Review B. 677753032003
Topological networks for quantum communication between distant qubits. Nicolai Lang, Hans Peter Büchler, npj Quantum Information. 2017347
When entanglement meets classical communications: Quantum teleportation for the quantum internet. Angela Sara Cacciapuoti, Marcello Caleffi, Rodney Van Meter, Lajos Hanzo, IEEE Transactions on Communications. 6862020
Decoherence of entanglement in the bloch channel. Masashi Ban, Sachiko Kitajima, Fumiaki Shibata, Journal of Physics A: Mathematical and General. 381942352005
Quantum measurement of a solid-state qubit: A unified quantum master equation approach. Xin-Qi Li, Wen-Kai Zhang, Ping Cui, Jiushu Shao, Zhongshui Ma, Yijing Yan, Physical Review B. 698853152004
Coherent master equation for laser modelocking. Bruno Auro M Perego, François Garbin, Stephane Gustave, Franco Barland, Germán J De Prati, Valcárcel, Nature communications. 1113112020
Application of optimal control theory to the design of broadband excitation pulses for high-resolution nmr. Timo O Thomas E Skinner, Burkhard Reiss, Navin Luy, Steffen J Khaneja, Glaser, Journal of Magnetic Resonance. 16312003
Exact broadband excitation of two-level systems by mapping spins to springs. Jr-Shin Li, Justin Ruths, Steffen J Glaser, Nature communications. 814462017
Quantum decoherence. Maximilian Schlosshauer, Physics Reports. 8312019
Reducing qubit requirements for quantum simulations using molecular point group symmetries. Kanav Setia, Richard Chen, Julia E Rice, Antonio Mezzacapo, Marco Pistoia, James D Whitfield, Journal of Chemical Theory and Computation. 16102020
Learning k-qubit quantum operators via pauli decomposition. Mohsen Heidari, Wojciech Szpankowski, International Conference on Artificial Intelligence and Statistics. PMLR2023
Classical correlation and quantum discord mediated by cavity in two coupled qubits. Cheng-Zhi Wang, Chun-Xian Li, Liu-Ying Nie, Jiang-Fan Li, Journal of Physics B: Atomic, Molecular and Optical Physics. 441155032010
Ideas of quantum chemistry. Lucjan Piela, 2013Elsevier
Vittorio Vitale, Tiago Mendes-Santos, Alex Rodriguez, Marcello Dalmonte, arXiv:2305.05396Topological kolmogorov complexity and the berezinskii-kosterlitz-thouless mechanism. 2023arXiv preprint
Quantum information processing, quantum computing, and quantum error correction: an engineering approach. Ivan B Djordjevic, 2021Academic Press
Euclidean distance matrices and applications. Nathan Krislock, Henry Wolkowicz, 2012Springer
Kullback-leibler divergence. Solomon Kullback, 1951
The jensen-shannon divergence. Ml Menéndez, Pardo, Pardo, Pardo, Journal of the Franklin Institute. 33421997
The divergence and bhattacharyya distance measures in signal selection. Thomas Kailath, IEEE transactions on communication technology. 1511967
Feature extraction based on the bhattacharyya distance. Euisun Choi, Chulhee Lee, Pattern Recognition. 3682003
| [
-0.1728760004043579,
-0.04503386467695236,
-0.06384162604808807,
0.07962708920240402,
-0.08774203807115555,
-0.07656867802143097,
-0.17404873669147491,
-0.21023902297019958,
-0.037792712450027466,
0.008691564202308655,
-0.00812038965523243,
-0.09256313741207123,
0.032294705510139465,
0.006... |
ON PURE SUBRINGS OF SP-GROUPS
15 Jan 2024
A Amini
B Amini
E Momtahan
ON PURE SUBRINGS OF SP-GROUPS
15 Jan 20244D6EF41582C066662C1BAFE7DEA650D5arXiv:2401.07742v1[math.GR]Abelian sp-groupsEndomorphism ringpure subring
Let G be a sp-group such that for every prime p, G p is elementary.We show that End Z (G) is a sp-group and every subring R of End Z (G p ), con-where T is a subring of p∈P End(G p ).We observe that MT ⊕ p∈P End(Gp) is (ring) isomorphic with T ⊗ Z Q.Moreover, we conclude that a significant number of the examples around the topic can be easily obtained and described by choosing an appropriate subring T .2010 Mathematics Subject Classification.20K25, 20K21.
Following [6], a reduced group G with infinitely many nonzero p-components satisfying the equivalent conditions of the next proposition is called an sp-group.
Proposition 1. [6, Proposition 1.4] Let G be a reduced mixed group which has infinitely many nonzero p-components.The following properties of the group G are equivalent.
(1) For every prime p, we have the direct decomposition G = G p ⊕ B p for some group B p with pB p = B p .(2) The embeddings
⊕G p < G ≤ G p ,
hold and G is pure subgroup of G p .(3) The embeddings from item (2) hold and G Gt is a divisible group.(4) The p-component G p is a direct summand of the group G for every prime p and G Gt is a divisible group.
In this article we deal mainly with sp-groups with elementary p-components, that is, for every prime p, G p is a direct sum of cyclic groups of order p.By group we always mean an Abelian group and and ⊕, denote p∈P End(G p ) and ⊕ p∈P End(G p ) respectively, unless otherwise stated.Since for every prime p, G p is an elementary p-group, End Z (G p ) is (ring) isomorphic with End Zp (V ), where V is a (right) vector space over Z p .Hence is a regular right self-injective ring.When for every p, G p is finite, or equivalently End(G p ) = M np (Z p ), is right and left self-injective.Also G t denotes the torsion subgroup of G and G t = ⊕ p∈P G p .A subring R of is said to be pure if its additive group is a pure subgroup of .We say that a subgroup H of a group G is pure if for every n ∈ N, nH = H ∩ nG.By a regular ring we always mean regular in the sense of von Neumann (for a systematic study of regular rings see [4]).A ring R is said to be right ℵ 0 -self-injective (p-injective) if for every (module) homorphism f ∈ Hom R (I, R), there exists f ∈ Hom R (R, R), such that f |I = f , where I is any countably generated (principal) right ideal of R. The reader is referred to [7] and [1], for undefined terms and notations.
In the sequel we need a lemma, which has partially generalized some parts of the aforementioned proposition.
Lemma 2. Let G be an Abelian group, such that ⊕G p ≤ G ≤ G p and for every p, G p is elementary.Then G is a pure subgroup of G p if and only if for every p, G = G p ⊕ pG.
Proof.Let G be pure, and p is a prime number.It is clear that
G p = G p ⊕ q =p G q = G p ⊕p G p .
Now by modular law and the fact that G is pure, we have G = G p ⊕(G∩p G p ) = G p ⊕pG.Conversely, suppose that for every prime p, G = G p ⊕pG.This immediately implies that pG = p 2 G and hence pG = p n G for every n ∈ N.For two distinct prime numbers p and q, we have G = G p ⊕ G q ⊕ pqG.This can be easily generalized to any finite number of prime numbers.Now suppose that n
= p α 1 1 • • • p α k k is a natural number, then G ∩ n G p = nG ⊕ (G p 1 ⊕ • • • ⊕ G pn ∩ n G p ) = nG.(G) ⊆ Hom Z (G t , G) = End Z (G t ) = End Z (G p )
(recall that Hom Z ( G Gt , G) = 0 due to G Gt being divisible and G being reduced).Now we show that End Z (G) is a pure subring of End Z (G) p .Since End(G) p = End(G p ), we conclude that End(G) ≤ End(G) p .Using Lemma 3, it is enough to show that End Z (G) = End Z (G) p ⊕ pEnd Z (G) for every prime p.According to the equality End(G) = End(G p )⊕End(pG), we have to show that End(pG) = pEnd(G).We know that pEnd(G) = pEnd(pG).Hence we show that End(pG) = pEnd(pG).Suppose that f ∈ End(pG) and x ∈ pG.We see that f (x) = py for some y ∈ pG, due to this fact that pG = p 2 G. Now define h : pG −→ pG with h(x) = y.The map h is well-defined, because if f (x) = py = pz for some y, z ∈ pG, then p(y − z) = 0, i.e., y − z = 0 (remind that pG ∩ G p = 0).That is f = ph, for h ∈ End(pG), this proves that End(pG) = pEnd(pG).Therefore, End(G) is a pure subring of End(G) p .
Note that under the assumptions of Proposition 3, End(G) is a pure subring of .In the following we characterize the format of all pure subrings of .Definition 4. Let T be a subset of .Then by M T , we mean
{x ∈ | ∃k ∈ N such that kx ∈ ⊕ + T }.
If, in addition, T satisfies in this property that when x ∈ T , then kx ∈ T for every k ∈ Z (e.g., T is a subgroup of ), then M T can be equivalently defined as
M T = {x ∈ | ∃k ∈ N such that kx ∈ T }.
Theorem 5. Let T be a subring of , then the following hold:
(1) M T is a pure subring of , containing ⊕ + T.
(
) M T ⊕ is (ring) isomorphic with T ⊗ Q. (3) M T is a regular ring if and only if T ⊗ Q is a regular ring.2
If in addition, for every p, G p is finite, the following facts hold either: (4) M T is right and left non-singular.(5) is a right (a left) maximal quotient ring of
M T . (6) M T is never right or left ℵ 0 -self-injective ring unless M T = . (7) |M T | = |T |.
Proof.(1): Let x, y ∈ M T , we know that there exist k, l ∈ N such that kx = s and ly = t, where s, t ∈ T .We observe that kl(xy) = (kx)(ly) = st ∈ T .On the other hand kl(x + y) = l(kx) + k(ly) = ls + kt which belong to T as well.This shows that M T is a ring.We claim that M T is a pure subgroup of , i.e., for n ∈ N, we have M T ∩ n = nM T .To show this, suppose that x ∈ M T ∩ n , so x = ny for some y ∈ and there exists k ∈ N such that kx ∈ T , so kny ∈ T , hence y ∈ M T , so x ∈ nM T .
(2) Define φ :
M T −→ T ⊗ Q with φ(x) = t ⊗ 1 k , where k ∈ N, t ∈ T and kx = t ∈ T . First of all, we show that φ is well-defined. Suppose that for x ∈ M T , there are k, k ′ ∈ N such kx = t and k ′ x = t ′ . Note that k ′ kx = k ′ t = kt ′ , which implies that k ′ t ⊗ 1 kk ′ = kt ′ ⊗ 1 kk ′ . Hence t ⊗ 1 k = t ′ ⊗ 1 k ′ , i.e.
, φ is well-defined.Now we show that φ is a ring homomorphism.To show that φ(x + y) = φ(x) + φ(y), suppose that for x, y ∈ M T , there are k, l ∈ N such that kx = s and ly = t.Now consider lkx = ls and kly = kt,we have kl(x + y) = ls + kt, this implies that φ(x
+ y) = ls + kt ⊗ 1 kl , but ls ⊗ 1 kl + kt ⊗ 1 kl = s ⊗ 1 k + t ⊗ 1 l = φ(x) + φ(y). Now, since klxy = (kx)(ly) = st, we have φ(xy) = st ⊗ 1 kl = (s ⊗ 1 k )(t ⊗ 1 l ) = φ(x)φ(y)
. Furthermore, we show that φ is onto.Without loss of generality we may suppose that s ⊗ 1 k ∈ T ⊗ Q, now the equation k(x + ⊕) = s + ⊕ is solvable, due to /⊕ being divisible.Hence, there exists x ∈ such that kx = s + a, where a ∈ ⊕.There exists l ∈ N such that la = 0, so lkx = ls, therefore x ∈ M T and φ(x) = ls ⊗ 1 lk = s ⊗ 1 k .Now we show that ker φ = ⊕.To observe this, recall first that T ⊗ Q ∼ = S −1 T , where S = Z \ {0}.Now t ⊗ 1 k = 0 if and only if there exists n ∈ Z \ {0} such that nt = 0, i.e., t ∈ ⊕, due to G p is elementary for every prime p, i.e., ker φ = ⊕.
(3) Since ⊕ is regular, we deduce that M T is regular if and only if T ⊗Q is a regular ring.
(4) Since ann (⊕)∩M T = ann M T (⊕) and ann (⊕) = (0), we have ann [7,Proposition 7.13]).Thus M T is right and left non-singular.
M T (⊕) = (0). But Soc(M T ) = ⊕, hence Z(M T ) ⊆ ann(Soc(M T )) = (0) (see
(5) Since ⊕ is an essential ideal of , and by ( 4), M T is non-singular, we are thorough by [7, Proposition 13.39,( 2
M I ∼ = T ⊗Q I⊗Q ∼ = T I ⊗ Q. (ii)
In general, it is not the case that every pure subring of , contains ⊕.For example, consider R = T 2 (Z p ) which is a pure subring of M 2 (Z p ), where by T 2 (Z p ) we mean the subring of all upper triangular matrices of M 2 (Z p ).However, the next result shows that those pure subrings of , which contain ⊕, have the M T shape.
M R = R. It is clear R is a subring of M R . Now let x ∈ M R , then there exists k ∈ N such that kx ∈ ⊕ + R = R. Hence kx ∈ (R ∩ k ), but R is pure, hence R ∩ k = kR,
which implies that kx ∈ kR, i.e., kx = kr, for r ∈ R. Thus k(x − r) = 0, or equivalently x − r ∈ ⊕ ⊂ R, and hence x − r, r ∈ R, so x ∈ R.
The Curious Case of p∈P Z p
In the last few decades, one of the main sources of examples and counter-examples of sp-groups was p∈P Z p .This gives us permission to examine this particular but important case closely.One of the goals of this section is to take a fresh look at some old examples in this field.We will also construct other examples while scrutinizing the old ones.
The first close attentions to regular subrings of p∈P Z p , containig ⊕ p∈P Z p , very likely, goes back to [2], where the authors proved their embedding theorem, i.e., every regular ring is embedded in a regular ring with identity.To do this, they constructed a regular ring M with 1 as follows.Let ε p , be the identity of Z p and ε = (• • • , ε p , • • • ) be the identity of p∈P Z p .Now consider the quotient p∈P Zp ⊕ p∈P Zp , which is a torsion-free divisible ring in which the pure subgroup generated by the coset of ε is a ring M ⊕ p∈P Zp , isomorphic to Q.In this way, they obtained a subring M of p∈P Z p which contains ε as its identity and contains every Z p .This M is regular: it contains the regular ring ⊕ p∈P Z p , as an ideal modulo which M is regular and they proved every regular ring is a unital M-algebra.For more information on M, see [2], page 286.In Example 11, we observe that M is but only a first step towards a large class of pure subrings.Before that we need a simple but useful lemma.Lemma 8. Let α be a cardinal number which is less or equal than ω.Then Z α is contained in p∈P Z p as a subring.
Proof.We first provide a proof for the case α = ω.We may partition P into ℵ 0 parts, each of which has infinite elements.Suppose that P = ∞ i=1 A i , and
A i ∩ A j = ∅, when i = j and |A i | = ℵ 0 for every i ∈ N. Now we have p∈P Z p ∼ = p∈A 1 Z p × p∈A 2 Z p × • • • But Z is contained in p∈A i Z p for every i ∈ N, which means that Z ω ⊂ p∈P Z p .
The proof for α < ω is almost the same.
The following Proposition has been first appeared in [9, Lemma 2].We give a proof for the sake of completeness.Note that, in contrast to Remark 6, part (ii), it is not difficult to show that a pure subring of p∈P Z p always contains ⊕ p∈P Z p .Proposition 9. Let M be a subring of p∈P Z p , containing ⊕ p∈P Z p and for every p ∈ P, M = M p ⊕ pM (i.e., M is a pure subring of p∈P Z p ), then End Z (M) = M.
Proof.We show that the map φ : M −→ End Z (M) with φ(a) = λ a is an isomorphism, where λ a : M −→ M is defined by λ a (x) = ax.It is clear that φ is a monomorphism.We show that φ is onto.Let f ∈ End Z (M), we know that
End Z (M) ⊆ Hom(M, p∈P Z p ) = p∈P Hom(M, M p ).
Recall that here M p = Z p .Now we define
f p : M −→ Z p by f p := π p • f (π p : p∈P Z p −→ Z p ). So for every x ∈ M, f (x) = ((f p (x))) p∈P . By hypothesis M = Z p ⊕ pM, so Hom(M, Z p ) = Hom(Z p ⊕ pM, Z p ) ∼ = Hom(Z p , Z p ) ⊕ Hom(pM, Z p ) ∼ = Hom(Z p , Z p ) ∼ = Z p . Therefore, for every f p ∈ Hom(M, Z p ), there exists a p ∈ Z p such that f p ((x p )) = a p x p . We observe that f (x) = f ((x p ) p∈P ) = (f p (x)) p∈P = (a p )(x p ) = λ a (x)
, where a = (a p ) p∈P .Since f (1) = λ a (1) = a, we conclude that a ∈ M and φ is onto, i.e., End Z (M) ∼ = M. Remark 10.All pure subrings M T , which have been introduced in this section are subject to Proposition 9, and therefore End(M T ) = M T .
Example 11.Going back to Fusch-Halperin's example, we easily observe that M = {x ∈ p∈P Z p | ∃k ∈ N such that kx is eventually constant}.Looking again at M, we may redefine it as M Z = {x ∈ p∈P Z p | ∃k ∈ N such that kx ∈ Z}.In general, let n ∈ N be given, we may define
M Z n = {x ∈ p∈P Z p | ∃k ∈ N such that kx ∈ Z n }. Furthermore, we define M Z ω as {x ∈ p∈P Z p | ∃k ∈ N such that kx ∈ Z ω }.
Just for simplicity's sake, we use notations M n and M ω instead of M Z n and M Z ω respectively.A reason for regularity of M n is that Mn
⊕ p∈P Zp ∼ = Z n ⊗ Q ∼ = Q n . However, M ω is not regular. By Theorem 5, Mω ⊕ p∈P Zp ∼ = Z ω ⊗ Q.
The right hand side ring is isomorphic to a subalgebra of Q ω consisting of those sequences of rational numbers whose denominators are bounded (with respect to suitable (not any) representations as fractions).That is
Z ω ⊗ Q ∼ = A = { x ∈ Q ω | x = ( b 1 k , b 2 k , b 3 k , • • • ) for k ∈ N}, which is not regular. To see this, It is enough to consider the element a = ( 1 2 , 3 2 , 5 2 , 7 2 , • • • ).
It is clear that there is no element l ∈ A such that ala = a.Moreover, it is worth mentioning that M ω is not even a p-injective ring, otherwise it were regular due to M ω being reduced.
Remark 12. (I) Let n ≥ 2, we can partition P into n (infinite) subsets, in exactly 2 ℵ 0 ways.According to each of these partitions, we have an M n .The sum of all these M n 's for a fixed n, i.e., M n , is a regular Baer subring of p∈P Z p , which contains all idempotents of it (see Example 13).(II) In general we cannot say that M n is a subring of M k , where k ≥ n, but there are ways of partitioning P, in which M 1 ⊂ M 2 ⊂ • • • .Also there are uncountably many chains like this.
Example 13.Rangaswamy in [9] -in a remark that appeared on page 357 of the article -has found a regular Baer subring B of p∈P Z p , which is not self-injective.The ring B is the subring generated by M 1 and all idempotents of p∈P Z p .Following Theorem 5, put T = Ze, where e runs over all idempotents of p∈P Z p .Then B = M T .In the sequel, we reveal the relation between B and M n 's.As we have already mentioned in Remark 12, there is only one M 1 (as there is only one Z in p∈P Z p ), but for every n ≥ 2, we have uncountably many M n (as there are uncountably many Z n in p∈P Z p ).Let M n denote the set of all M n 's.It can be shown that Mn∈Mn M n is equal to the B. Since
⊕ p∈P Z p ⊕ Z n ⊂ M n , we may write 1 = ǫ = ǫ 1 + • • • + ǫ n , where by ǫ i we mean (0, • • • , 1, • • • , 0), where 1 is in the ith component. So M n = M 1 ǫ 1 + • • • + M 1 ǫ n .
On the other hand, every idempotent in p∈P Z p belongs to some M n , for every n ≥ 2. It is also worth mentioning that B = Mn∈Mn M n is continuous as well, because it contains all the idempotents of its maximal quotient ring, i.e., p∈P Z p (see [4,Theorem 13.13]) .On the other hand, we are allowed to write
Mn∈Mn M n = {x ∈ p∈P Z p | ∃k ∈ N such that kx ∈ Z n },
where the right hand sum is taken over all (uncountably many) Z n in p∈P Z p .
Example 14.We may consider the increasing sequence of regular rings
M 1 < M 2 < • • • , then lim − →
M n is a regular subring of p∈P Z p (direct limits of regular rings are regular).The ring is obviously different from M n 's and M ω .In fact
lim − → M n = {x ∈ p∈P Z p | ∃k ∈ N such that kx ∈ lim − → Z n }. Since lim − → Z n ⊂ Z ω , we conclude that lim − → M n is a proper subring of M ω .
The following example is another instance of a regular pure subring which is not of finite torsion free rank.
Example 15.Let T = Z (ω) + 1.Z be a subring of p∈P Z p , then
M T ⊕Zp ∼ = T ⊗ Q ∼ = Q (ω) + 1Q which is a (regular) subring of Q ω . Since lim − → Z n = T , we deduce that lim − → M n = M T .
The next example has been considered in [3,Example 4.3] as a pp-subring (i.e., pricipal ideals are projective) of p∈P Z p which is not regular.In the following, we put the example in the format of M T , where T is an appropriate subring of p∈P Z p .It is worth mentioning that a "Cantor-like" proof can be used to show that p∈P Z p , has 2 ℵ 0 transcendental elements (non-integral elements) over Z. Hence the number of algebraic (integral) elements over Z is ℵ 0 .But to see a concrete non-integral -in fact transcendental-element in p∈P Z p , take the element d = (1, 2, 2, 2, • • • ) ∈ p∈P Z p .Then where d has already been defined in the above (which is transcendental over Q) (see [3,Example 4.3]).According to Theorem 5, we have:
M T ⊕Z p ∼ = T ⊗ Q ∼ = Z[x] ⊗ Q ∼ = Q[x],
which is clearly not regular.
7 )
7
)]. (6) Let M T be a proper subring of .By (4), M T is non-singular and Soc(M T ) = ⊕ is countably generated.If M T were ℵ 0 -self-injective, it were self-injective, due to [8, Corollary 4.4], but this is not the case because the maximal quotient ring of M T is .(In as much as | M T ⊕ | = |T ⊗ Q| = |T | and | ⊕ | = ℵ 0 , we have |M T | = ℵ 0 |T | = |T |.Remark 6. (i) Let T be a subring of and I be a right ideal of T ; then M I is a right ideal of M T , containing ⊕ and M T
Proposition 7 .
7
Let R be a subring of containing ⊕, then R is a pure subring if and only if there exists a subring T of such that R = M T .Proof.(⇐) it has already proved in Theorem 5, part 1.(⇒): Let R be a pure subring of , we show that
1 d = d − 1 = ( 1 , 2 − 1 , 2 − 1 , 2 − 1 ,
11212121
• • • ) exists in p∈P Z p .This 1 d is actually equal to (1, 2, 3, 4, 6, • • • ) ∈ p∈P Z p .We show that d −1 is not integral (and algebraic) over Z.Let d −n + n i=1 b i d −n+i = 0, which implies that 1 + n i=1 b i d i = 0.That is 1 + n k=1 2 k b k = 0 ∈ Z p for p ≥ 3.For those prime numbers p which are enough large it is not possible.The same method shows that d −1 is transcendental.Example 16.We may redefine the ring which has been introduced in [3, Example 4.3] as follows: put T = Z[d], and define M T = {x ∈ p∈P Z p | ∃k ∈ N such that kx ∈ Z[d]},
Proof.Since for every prime p, G = G p ⊕ pG and pG = p 2 G, we conclude that Hom Z (G p , pG) and Hom(pG, G p ) are both zero.Therefore EndZ (G) = End Z (G p ) ⊕ End Z (pG).Thus, ⊕End Z (G p ) is contained in End Z (G).Now consider the short exact sequence 0 → G t → G → GGt → 0 and apply the functor Hom(−, G), we get End Z
Proposition 3. Let G be a sp-group, such that for every prime p, G p is elementary.Then End Z (G) is a sp-group.
L Fuchs, Infinite Abelian groups. New York and LondonAcademic press19732
On the imbedding of a regular ring in a regular ring with identity. L Fuchs, I Halperin, Fund. Math. 541964
Regular and principal projective endomorphism rings of mixed Abelian groups. S Glaz, W Wickless, Comm. Algebra. 2241994
Regular rings. K Goodearl, 1991Kriger Publishing CompanyMalabar, Floridasecond edition
Endomorphisms of Abelian groups. P A Krylov, Alexander V Mikhalev, Askar A Tuganbaev, 2003Kluwer Academic Publishers
P A Krylov, A A Tuganbaev, A V Tsarev, SP-groups and their endomorphism rings. July, 2021256
T Y Lam, Lectures on Modules and Rings. New YorkSpringer-Verlag1999
E Momtahan, On ℵ 0 -injectivity. 200432
Regular and Baer rings. K M Rangaswamy, Proc. A.M.S. A.M.S197442
Abelian groups with Endomorphic Images of special types. K M Rangaswamy, J. Algebra. 61967
Iran Email address: bamini@shirazu.ac.ir Ehsan Momtahan. K M Rangaswamy, Math. Ann. 1901970. 71457. 71457Afshin Amini, Department of Mathematics, College of Sciences, Shiraz University ; Department of Mathematics, College of Sciences, Shiraz University ; Department of Mathematics, Yasouj University, YasoujIran Email address: aamini@shirazu.ac.ir Babak Amini. Iran Email address: e-momtahan@mail.yu.ac.ir
| [
-0.1856417953968048,
-0.00630537886172533,
-0.010237747803330421,
0.02073797397315502,
0.11304923892021179,
-0.028058787807822227,
0.21796515583992004,
0.05837485194206238,
-0.004686364438384771,
-0.13704927265644073,
0.08106961846351624,
0.05229450762271881,
0.08482874184846878,
0.0143221... |
Controlling the 2D magnetism of CrBr 3 by van der Waals stacking engineering
August 23, 2023
Shiqi Yang
School of Physics
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics
Peking University
100871BeijingChina
Xiaolong Xu xuxiaolong@bit.edu.cn
School of Integrated Circuits and Electronics
MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices
Beijing Institute of Technology
100081BeijingChina
Bo Han
School of Physics
International Center for Quantum Materials
Electron Microscopy Laboratory
Peking University
100871BeijingChina
International Center for Quantum Materials
School of Physics
Peking University
100871BeijingChina
Pingfan Gu
School of Physics
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics
Peking University
100871BeijingChina
Roger Guzman
School of Physical Sciences
University of Chinese Academy of Sciences
100049BeijingChina
Yiwen Song
School of Physics
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics
Peking University
100871BeijingChina
Zhongchong Lin
School of Physics
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics
Peking University
100871BeijingChina
Peng Gao
School of Physics
International Center for Quantum Materials
Electron Microscopy Laboratory
Peking University
100871BeijingChina
International Center for Quantum Materials
School of Physics
Peking University
100871BeijingChina
Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials
Peking University
100871BeijingChina
Collaborative Innovation Centre of Quantum Matter
100871BeijingChina
Wu Zhou
School of Physical Sciences
University of Chinese Academy of Sciences
100049BeijingChina
Jinbo Yang
School of Physics
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics
Peking University
100871BeijingChina
Zuxin Chen chenzuxin@m.scnu.edu.cn
School of Semiconductor Science and Technology
South China Normal University
528225FoshanChina
Yu Ye yeyu@pku.edu.cn
School of Physics
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics
Peking University
100871BeijingChina
Collaborative Innovation Centre of Quantum Matter
100871BeijingChina
Yangtze Delta Institute of Optoelectronics
Peking University
226010Nantong, JiangsuChina
Liaoning Academy of Materials
110167ShenyangChina
Controlling the 2D magnetism of CrBr 3 by van der Waals stacking engineering
August 23, 202307FB68C1992AD52CF372C52C878CCAB1
The manipulation of two-dimensional (2D) magnetic order is of significant importance to facilitate future 2D magnets for low-power and high-speed spintronic devices.Van der Waals stacking engineering makes promises for controllable magnetism via interlayer magnetic coupling.However, directly examining the stacking order changes accompanying magnetic order transitions at the atomic scale and preparing device-ready 2D magnets with controllable magnetic orders remain elusive.Here, we demonstrate effective control of interlayer stacking in exfoliated CrBr3 via thermally assisted strain engineering.The stable interlayer ferromagnetic (FM), antiferromagnetic (AFM), and FM-AFM coexistent ground states confirmed by the magnetic circular dichroism measurements are realized.Combined with the first-principles calculations, the atomically-resolved imaging technique reveals the correlation between magnetic order and interlay stacking order in the CrBr3 flakes unambiguously.A tunable exchange bias effect is obtained in the mixed phase of FM and AFM states.This work will introduce new magnetic properties by controlling the stacking order, and sequence of 2D magnets, providing ample opportunities for their application in spintronic devices.
Van der Waals materials with intrinsic magnetism have attracted tremendous attention due to their atomic-scale thickness that can be used to realize integrable and flexible magnetic devices [1][2][3][4][5].Effective control of their magnetic orders is the real power with which we can fabricate all kinds of spintronic devices.In particular, when twodimensional (2D) magnetism was first demonstrated [1], it was surprising to find that the exfoliated thin CrI 3 behaves as an A-type antiferromagnetic (AFM) semiconductor with intralayer ferromagnetic (FM) coupling and interlayer AFM coupling, while the bulk CrI 3 crystal behaves as a ferromagnet at low temperatures.A large number of subsequent experiments and theories confirmed that this intriguing difference comes from the change of the interlayer magnetic coupling caused by the different stacking order in CrI 3 and CrCl 3 [6][7][8][9][10][11][12][13].Specifically, CrI 3 crystal undergoes a transition from the monoclinic (M) phase to rhombohedral (R) phase below room temperature [14][15][16][17] and exhibit interlayer FM coupling at low temperature, while exfoliated thin layers of CrI 3 will maintain the monoclinic phase at low temperatures, which manifests as interlayer AFM coupling.
Based on these understandings, strategies such as hydrostatic pressure have been proposed to effectively control the interlayer stacking order and thus their magnetic properties [6][7][8][9][18][19][20][21], and recently promote the extensive development of moiré magnetism [22][23][24][25].Nevertheless, the correlation between crystal structure and magnetic order is mainly characterized by optical means such as Raman spectroscopy and nonlinear optics [6][7][8]10], and the verification of atomic resolution is still lacking.Surprisingly, as an isostructural material, both bulk and exfoliated CrBr 3 flakes have been demonstrated and widely used as perfect ferromagnetic semiconductors [26][27][28][29][30].The remaining questions are (1) what is the essential difference of CrBr 3 compared with CrI 3 and CrCl 3 , and (2) is there an effective method to control the magnetic order of CrBr 3 ?
Unlike CrI 3 and CrCl 3 crystals that transition from M phase to R phase at low temperatures [14][15][16][17], earlier work predicted that CrBr 3 would undergo this structural phase transition above room temperature [31], but it has not been experimentally confirmed.Additionally, previous pioneering work verified the correlation between the arXiv:2308.11219v1[cond-mat.mtrl-sci]22 Aug 2023 interlayer magnetic coupling and the stacking order in molecular beam epitaxy-synthesized CrBr 3 bilayers by in situ spin-polarized scanning tunneling microscopy [32].Based on the better stability of CrBr 3 and the expected structural phase transition above room temperature [30][31][32][33], it provides a unique platform for effectively controlling the magnetic order through van der Waals stacking engineering, which is crucial for the realization of related spintronic devices.Here, effective interlayer stacking control is achieved in exfoliated CrBr 3 flakes by thermally assisted strain engineering, and the correlation between van der Waals stacking order and magnetic order is verified at the atomic scale unambiguously.
We start with the crystallographic structure of bulk CrBr 3 crystals.The single-crystal X-ray diffraction (SC-XRD) spectrum of the as-grown CrBr 3 crystal collected at 273 K (Supplementary Table 1) gives an R structure (R 3, a = 6.306Å, c = 18.372Å), different from the M phase of CrI 3 and CrCl 3 crystals at room temperature [14][15][16].In a single-layer CrBr 3 , Cr atoms form a honeycomb structure surrounded by six octahedrally coordinated Br atoms (Fig. 1a).Sliding along the high-symmetry [1 10] direction and stacking these monolayers will yield R phase of CrBr 3 (left panel of Fig. 1b).Magnetic measurements of CrBr 3 crystal re-veals long-range ferromagnetism with a Curie temperature (T c ) of about 33 K and exhibit an out-of-plane magnetic anisotropy with a relatively low spin-flip field (∼ 0.25 T) (Supplementary Fig. S1), indicating that the room-temperature (RT) CrBr 3 R phase corresponds to interlayer FM coupling at temperatures below its T c .
To fully understand the evolution of the crystal structure with temperature, especially to identify possible structural phase transition, powder XRD measurements were performed on CrBr 3 crystals between 300 K and 548 K. Figure 1c shows the temperature-dependent XRD measurements during one warming process.Near 378 K, the diffraction angle is clearly split into two peaks at 59.70°and 59.77°, which are almost linearly red-shifted with increasing temperature on each side of 378 K, respectively, indicative of a temperature-induced structure phase transition.The significant thermal hysteresis during cooling and warming processes demonstrates the firstorder nature of the transition (Supplementary Fig. 2).Differential scanning calorimetry measurement further confirmed the phase transition with an endothermic peak at an exact temperature of 373.7 K (Supplementary Fig. 2).Is the HT phase the M phase (right panel of Fig. 1b, CrBr 3 monolayers slide along the [100] direction and stack, C2/m) as we expected, and what is its magnetic order?However, once cooling down, the HT phase will transform back to the RT R phase, which hinders us from revealing the crystal structure and magnetic properties of the HT phase.
Given the knowledge from extensive research on chromium trihalides [6][7][8][9][10][11][12][13][14][15][16][17], we propose a thermally assisted strain engineering approach to fix the CrBr 3 HT phase (Fig. 1d).In an argon-filled glove box, the CrBr 3 flakes were exfoliated onto the polydimethylsiloxane (PDMS) substrate, and then the PDMS was care-fully stretched several times on a hot plate set at 423 K.The stretched flakes subsequently transferred onto Si/SiO 2 substrates also display the same magnetic properties as those on PDMS substrates (Supplementary Fig. 3).The magnetic properties of few-layer CrBr 3 flakes were probed using reflective magnetic circular dichroism (RMCD) microscopy (see Methods for details).CrBr 3 flakes exfoliated and stretched at room temperature were first fabricated for comparison (Supplementary Fig. 4).The RMCD signal versus magnetic field of a ∼10 nm flake (Fig. 2a) shows a distinct hysteresis loop with a spin-flip field of 0.04 T at 2 K, confirming its FM nature with T c of about 33 K (Supplementary Fig. 5).When the thickness increases, the rectangular hysteresis vanishes and multiple magnetic transitions occur, which is in accordance with previous reports [26,30].
In the thermally assisted stretched CrBr 3 flakes, we observe drastically different behaviors from the FM flakes, and we can classify them into two categories.First, in the S1-class samples (Fig. 2b), a plateau with zero RMCD signal is shown within ±0.10 T, indicating typical AFM behavior.Then, the forced FM state is reached through a two-step spin-flip transition around 0.10 T and 0.40 T (H 1 and H 2 , marked by the dashed lines in Fig. 2b), which resembles the even-layer A-type AFM CrI 3 but with weaker interlayer exchange coupling [22].We speculate that the pure AFM state of CrBr 3 is also from the M phase, which will be verified later by scanning transmission electron microscopy (STEM) characterizations.As the temperature increase, the spin-flip fields decrease continuously and vanish around 27 K when the flake be-comes paramagnetic (Fig. 2d and Supplementary Fig. 6).The critical temperature of the AFM CrBr 3 flake (Néel temperature, T N ) is slightly lower than that of the FM flake (T c of 33 K).Second, apart from the pure AFM samples, the S2-class samples show obvious residual magnetic moment near zero magnetic field (indicating the presence of an FM component), and then undergo another spin-flip (H 2 ) to a forced FM state under high fields (Fig. 2c).The magnetic configuration of the S2 sample is different from that of the uncompensated odd-layer Atype AFM sample but exhibits the coexistence of FM and AFM components because (1) All S2-class samples with different thicknesses exhibit distinct FM signals around 0 T; (2) The spin-flip fields of H c and H 2 , and the resulting changes in the RMCD signals, do not show obvious thickness dependence (Supplementary Fig. 7); (3) H c and H 2 are distributed in wide ranges of 0-0.10 T and 0.27-0.42T, respectively (Supplementary Fig. 7), indicating that the FM and AFM components are coupled to each other; (4) The AFM features seem to disappear at a lower temperature than the FM features (Fig. 2e), con- First-principle calculations in a 2L CrBr 3 link crystal stacking and magnetic order.The transition from R to M phase can be regarded as the sliding of the 2 nd layer of CrBr 3 in the R phase.Density functional theory (DFT) calculations reveal the energy difference between the AFM state and the FM state during shifting from the R phase to the M phase (Fig. 2f).In the R phase, the FM state is more stable with an energy of 1.7 meV/Cr lower than the AFM state.As it approaches the M phase, the energy difference decreases and eventually crosses zero and becomes negative, indicating that the M phase is in the AFM ground state (Fig. 2g).This is consistent with our RMCD measurements of CrBr 3 RT FM phase and HT AFM phase.
To experimentally confirm the atomic structures of AFM and mixed-phase CrBr 3 samples and verify the correlation between magnetism and stacking order, we transferred representative FM, AFM, and mixed-phase samples after RMCD measurements onto copper microgrids for STEM characterizations.The high-angle annular dark-field (HAADF)-STEM image of the FM sample is highly consistent with the corresponding simulation results (Fig. 3a), and shows a uniform rhombohedral structure on a large scale (Supplementary Fig. 8), which agrees with the SC-XRD measurement results.For the AFM sample, the HAADF-STEM image shows an obvious anisotropic crystal structure (Fig. 3b).Comparison with the simulated monoclinic structure confirms that the stripe contrast is caused by the arrangement of Cr-Br (bright stripes) and Br hollow (dark stripes) atomic columns in the ab plane.RMCD measurements, and DFT calculations combined with STEM characterizations collectively confirmed that our thermally assisted strain process can engineer the van der Waals stacking in CrBr 3 , and thus effectively control its 2D magnetic properties.
Furthermore, HAADF-STEM of mixed-phase CrBr 3 samples exhibit a series of complex new periodic structures (Supplementary Fig. 8).Take the zoomed-in image of Fig. 3c as an example, a unit cell (marked by the white dashed lines) contains dark spots on the four corners and irregular distributed bright and less bright spots inside.The simulation result of the 7L R phase stacked vertically on the 7L M phase (right panel in Fig. 3c) agrees well with the experimental result.Fig. 3d-e show schematic diagrams of the atomic model in top and side views, illustrating the vertical stacking of coexisted R (FM state) and M (AFM state) phases in mixed-phase CrBr 3 .Small discrepancies between the simulation and experiment suggest that the exact vertical stacking in this structure may be more than a simple superposition of R and M phases, but complex combinations of the two components.
The coexistence of FM and AFM orders in the mixedphase CrBr 3 sample produces abundant AFM/FM interfaces (vertical and/or in-plane), which provide a platform for studying the exchange interactions established at the interfaces.Sweeping in a large magnetic field range of ±0.60 T, the FM component encounters a time-reversal symmetric AFM environment when flipping from up to down and down to up (Fig. 4a).The FM component within the minor hysteresis loop of ±0.10 T experiences a constant AFM environment, which would generate an unprecedented exchange bias (EB) effect due to the coupling between FM and AFM components.After being historically polarized by a positive saturation magnetic field of 0.60 T, the H c+ of the minor FM hysteresis loop shifts to the right, showing a positive EB with an exchange field of +12 mT (Fig. 4b).In contrast, after being polarized by a negative saturation magnetic field of −0.60 T, the H c− of the minor FM hysteresis loop shifts to the left, exhibiting a negative EB with an exchange field of −12 mT.The direction of this EB can be tuned by the historical polarization field, and the EB is rather stable under multiple back-and-forth magnetic field sweeps (Supplementary Fig. 9), suggesting that the mixed-phase CrBr 3 is an ideal platform for exploring interface physics and developing novel van der Waals magnet-based spintronic devices.
In summary, we experimentally realized effective control of interlayer magnetic coupling in exfoliated CrBr 3 flakes by a thermally assisted strain engineering approach and comprehensively demonstrated the correlation between atomically resolved stacking order and magnetism.In addition to the induction of pure FM and AFM magnetic ground states CrBr 3 flakes, we also reported mixedphase CrBr 3 composed of FM and AFM components, leading to a tunable exchange bias effect.The precise interfaces in the vertical stacking and in-plane connection should be further examined to better understand the mechanism and application of the exchange bias effect, which may require cryo-focused ion beam (cryo-FIB) milling and in-situ STEM characterization.Our work broadens 2D magnetic material systems for studying and manipulating magnetic couplings and related physical properties [27][28][29], making them promising candidates for next-generation spintronic devices.
Methods
Crystal synthesis and characterization.CrBr 3 single crystals were prepared by the chemical vapor transport (CVT) method [34].High-purity Cr (28.8 mg, Alfa, 99.996 %) and TeBr4 (371.2 mg, Alfa, 99.999 %) were mixed (molar ratio of 1:1.5) and then sealed in a silica tube under vacuum.Thereafter, the evacuated silica tube was placed in a two-zone tubular furnace.Crystal growth was carried out for 5 days under a temperature gradient from 750 °C to 450 °C, using a heating/cooling rate of 1 °C/min.Temperature-dependent power XRD measurements were performed using Cu-K radiation (λ = 1.5418Å).The magnetic properties of CrBr 3 crystals were measured using the physical properties measurement system (PPMS) produced by Quantum Design.Magneto-optical measurements.RMCD measurements were performed based on the Attocube closedcycle cryostat (attoDRY2100) with a temperature down to 1.6 K and an out-of-plane magnetic field up to 9 T. The detailed setup and measurement have been described in our previous work.STEM measurements.Atomic-resolution HAADF-STEM images were recorded using an aberrationcorrected Titan Themis G2 microscope operating at 300 kV.The convergence semi-angle is 30 mrad, and the collection angle is 39-200 mrad.Density functional theory calculations.Our density functional theory (DFT) calculations were carried out using generalized gradient approximation and projector augmented wave methods, as implemented in the Vienna ab initio simulation package (VASP).The uniform k mesh of 13131 was adopted for integration over the Brillouin zone (BZ).A plane-wave cutoff energy of 450 eV and a vacuum region larger than 15 Åwas used during the structural relaxations, and the residual force per atom in the optimized structures was less than 1 meV/ Å.We used the optB86b functional for structural-related calculations and the PBEsol function for energy comparisons among different magnetic configurations.The on-site Coulomb interaction to the Cr d orbitals had U and J values of 3.9 eV and 1.1 eV, respectively, as revealed by a linear response method and comparison with the experimental results.
Fig. 1 :
1
Fig. 1: Structure phase transition of bulk CrBr 3 crystals.a. Atomic structure of single-layer CrX 3 (X=Cl, Br, I).Cr atoms (blue spheres) form a honeycomb lattice structure surrounded by six X atoms (gray spheres), which are octahedrally coordinated.b.Crystal structures of rhombohedral (R, left) and monoclinic (M, right) CrBr 3 .c. Temperature-dependent (004) diffraction peak of CrBr 3 crystal measured by XRD during one arming process.The enlarged spectrum at 378 K shows a distinct two-peak behavior.d.Schematic illustration of thermalassisted strain engineering exfoliated CrBr 3 flakes.
Fig. 2 :
2
Fig. 2: Stacking-related magnetism in exfoliated CrBr 3 flakes.a-c.RMCD signal versus magnetic field sweeping curves of the FM CrBr 3 sample (a) prepared at room temperature, and the AFM (b) and mixed-phase (c) CrBr 3 samples prepared by thermal-assisted strain engineering process.The spin-flip fields are expressed as H c for FM CrBr 3 , H 1 and H 2 for AFM CrBr 3 .d-e.For S1 (d) and S2 (e) CrBr 3 samples, the RMCD signal plot in the parameter space of temperature and µ 0 H under descending field sweep.f.Schematic diagram of the magnetic ground state of 2L R and M phase CrBr 3 obtained by calculation.g.Calculated energy difference between AFM and FM states during 2L CrBr 3 shift from R phase to M phase.
Fig. 3 :
3
Fig. 3: STEM characterizations and corresponding simulations of FM, AFM, and mixed-phase CrBr 3 .a-b.HAADF-STEM images of FM (a) and AFM (b) CrBr 3 reveal the rhombohedral (a) and monoclinic (b) structures, in good agreement with the corresponding simulated images inset.The stripe contrast in the monoclinic structure is due to the arrangement of Cr-Br and Br hollow columns.c.HAAD-STEM image of a mixed-phase CrBr 3 , revealing a new periodic structure whose unit cell is marked by the white dashed lines.The right panel shows the simulation results of the vertically stacked 7L R phase and 7L M phase.d.The atomic arrangement of Cr and Br atoms in mixed-phase CrBr 3 utilized for HAADF-STEM simulations.e.Schematic of the atomic model illustrating the vertical stacking of R and M phases.
Fig. 4 :
4
Fig. 4: Exchange bias effects in the mixed-phase CrBr 3 at 2 K. a. RMCD signal versus µ 0 H for a mixedphase CrBr 3 sample (S3) at 2 K. Solid circles define the magnetic field sweep range in the exchange bias study.b-c.The RMCD signals versus µ 0 H swept within ±0.10 T after applying a saturation field of 0.60 T (b) or −0.60 T (c), yielding opposite exchange bias fields of +12 mT (b) and −12 mT (c).
AcknowledgementThis work was supported by the National Key R&D Program of China (No. 2022YFA1203902 and No. 2018YFA0306900), the National Natural Science Foundation of China (No. 12241401, No. 12250007 and No. 62274010), and Beijing Natural Science Foundation (No. JQ21018).We acknowledge the Electron Microscopy Laboratory of Peking University.Data availabilityThe source data generated in this study have been deposited in the database under the accession code (URL will be inserted before publication).Author contributionsX.X., Y.Y., and S.Y. conceived the project, designed the experiments, analyzed the results, and draft the manuscript.Z.C. grew the CrBr 3 bulk crystals.B.H., Y.S., and P. Gao performed the STEM characterizations.R.G. and W.Z. simulated the HAADF-STEM results.P. Gu performed the first-principle calculations.Z.L. and J. Y. performed the temperature-dependent power XRD and magnetic property measurements of bulk CrBr 3 crystals.All authors discussed the results and contributed to the manuscript.Competing interestsThe authors declare no competing financial interests.Additional informationSupplementary information is available for this paper at (URL need to be inserted).
Layer-dependent ferromagnetism in a van der waals crystal down to the monolayer limit. B Huang, Nature. 5462017
Discovery of intrinsic ferromagnetism in two-dimensional van der waals crystals. C Gong, Nature. 5462017
Magnetism in two-dimensional van der waals materials. K S Burch, D Mandrus, J.-G Park, Nature. 5632018
Two-dimensional magnetic crystals and emergent heterostructure devices. C Gong, X Zhang, Science. 36344502019
Magnetic 2D materials and heterostructures. M Gibertini, M Koperski, A F Morpurgo, K S Novoselov, Nature Nanotechnology. 142019
Switching 2D magnetic states via pressure tuning of layer stacking. T Song, Nature Materials. 182019
Pressure-controlled interlayer magnetism in atomically thin CrI3. T Li, Nature Materials. 182019
Enhancement of interlayer exchange in an ultrathin two-dimensional magnet. D R Klein, Nature Physics. 152019
Probing magnetism in 2D materials at the nanoscale with single-spin microscopy. L Thiel, Science. 3642019
Giant nonreciprocal second-harmonic generation from antiferromagnetic bilayer CrI3. Z Sun, Nature. 5722019
Stacking tunable interlayer magnetism in bilayer CrI3. P Jiang, Physical Review B. 991444012019
Interplay between interlayer exchange and stacking in CrI3 bilayers. D Soriano, C Cardoso, J Fernández-Rossier, Solid State Communications. 2991136622019
Microscopic understanding of magnetic interactions in bilayer CrI3. S W Jang, M Y Jeong, H Yoon, S Ryee, M J Han, Physical Review Materials. 3310012019
Coupling of crystal structure and magnetism in the layered, ferromagnetic insulator CrI3. M A Mcguire, H Dixit, V R Cooper, B C Sales, Chemistry of Materials. 272015
X-ray diffraction and nuclear quadrupole resonance studies of chromium trichloride. B Morosin, A Narath, The Journal of Chemical Physics. 401964
Crystal and magnetic structures in layered, transition metal dihalides and trihalides. M A Mcguire, Crystals. 71212017
Structural properties of chromium (iii) iodide and some chromium (iii) mixed halides. L Handy, N Gregory, Journal of the American Chemical Society. 741952
Electric-field switching of two-dimensional van der waals magnets. S Jiang, J Shan, K F Mak, Nature Materials. 172018
Electrical control of 2D magnetism in bilayer CrI3. B Huang, Nature Nanotechnology. 132018
Controlling magnetism in 2d cri3 by electrostatic doping. S Jiang, L Li, Z Wang, K F Mak, J Shan, Nature Nanotechnology. 132018
Exchange magnetostriction in two-dimensional antiferromagnets. S Jiang, H Xie, J Shan, K F Mak, Nature Materials. 192020
Direct visualization of magnetic domains and moiré magnetism in twisted 2D magnets. T Song, Science. 3742021
Coexisting ferromagnetic-antiferromagnetic state in twisted bilayer cri3. Y Xu, Nature Nanotechnology. 172022
Evidence of non-collinear spin texture in magnetic moiré superlattices. H Xie, Nature Physics. 162023
Electrically tunable moiré magnetism in twisted double bilayers of chromium triiodide. G Cheng, Nature Electronics. 2023
Magnetic domains and domain wall pinning in atomically thin crbr3 revealed by nanoscale imaging. Q.-C Sun, Nature communications. 121989. 2021
Micromagnetometry of two-dimensional ferromagnets. M Kim, Nature Electronics. 22019
Imaging and control of critical fluctuations in two-dimensional magnets. C Jin, Nature Materials. 192020
Evolution of interlayer and intralayer magnetism in three atomically thin chromium trihalides. H H Kim, Proceedings of the National Academy of Sciences. 1162019
Direct photoluminescence probing of ferromagnetism in monolayer two-dimensional CrBr3. Z Zhang, Nano Letters. 192019
X-ray diffraction and nuclear quadrupole resonance studies of chromium trichloride. B Morosin, A Narath, The Journal of Chemical Physics. 401964
Direct observation of van der waals stacking-dependent interlayer magnetism. W Chen, Science. 3662019
Raman spectroscopy, photocatalytic degradation, and stabilization of atomically thin chromium tri-iodide. D Shcherbakov, Nano letters. 182018
Accessing new magnetic regimes by tuning the ligand spin-orbit coupling in van der waals magnets. T A Tartaglia, Science Advances. 693792020
| [
-0.092025525867939,
0.005416315980255604,
-0.06766700744628906,
0.00006938166916370392,
0.03888127952814102,
-0.049290552735328674,
0.043305523693561554,
0.0030519862193614244,
-0.07997377216815948,
-0.018259013071656227,
0.04990479722619057,
-0.15194028615951538,
0.01179509237408638,
-0.0... |
Instantaneous Quantum Computation
December 13th, 2008
Dan Shepherd dan.shepherd@cesg.gsi.gov.uk
Department of Computer Science
University of Bristol
Woodland RoadBS8 1UBBristolUnited Kingdom
Michael J Bremner
Department of Computer Science
University of Bristol
Woodland RoadBS8 1UBBristolUnited Kingdom
Instantaneous Quantum Computation
December 13th, 2008DD22ED654EA8EA7BBFE2E73EE3AA0D81arXiv:0809.0847v3[quant-ph]
We examine theoretic architectures and an abstract model for a restricted class of quantum computation, called here temporally unstructured ("instantaneous") quantum computation because it allows for essentially no temporal structure within the quantum dynamics.Using the theory of binary matroids, we argue that the paradigm is rich enough to enable sampling from probability distributions that cannot, classically, be sampled from efficiently and accurately.This paradigm also admits simple interactive proof games that may convince a skeptic of the existence of truly quantum effects.Furthermore, these effects can be created using significantly fewer qubits than are required for running Shor's Algorithm.
Introduction 1.Mathematical motivation
It has often been said that underlying the power of quantum computers is the close connection between the computational model and the way we represent dynamics in quantum systems.This connection is implicit in the standard circuit model, where we require a universal gate set for an n-logical-qubit processor to be capable of simulating the dynamics of the n-qubit unitary group SU (2 n ).While there are many equivalent models of (universal) quantum computing, and not all of them explicitly 'generate' the special unitary group on n qubits, they each simulate (to within some pre-defined precision) operations drawn from some non-abelian unitary group on a set of qubits.Our approach in this paper departs from this well trod path, by focussing almost exclusively on an abelian subgroup of the unitary group.This approach is much more restrictive in the kinds of computation allowed, leading to a computational paradigm that lies somewhere between classical and universal quantum computing.
The non-abelian nature of quantum circuit elements is undoubtedly a crucial feature of universal quantum computing; for example, it imposes a clear physical limitation to the time-ordering of the gates in a circuit.In the standard model of quantum computation, the only circuits that can be performed in a single "time-step" are those composed only of single-qubit gates and two-qubit gates that act on disjoint sets of qubits.We often refer to such circuits as depth-1 circuits.When an abelian group is being used for the gates within a circuit, that circuit need not be depth-1 in the sense just described, though it will nonetheless be essentially devoid of temporal structure, since the order of the gates is immaterial.Physically, the quantum circuit model can be interpreted as applying a controlled sequence of unitary operations, which can in turn be thought of as a sequence of Hamiltonian evolutions.If any two consecutive gates in a sequence commute with one another, then their order in the sequence can be freely interchanged, or equivalently, their Hamiltonians can simply be combined additively, which corresponds to simultaneous evolution.When all gates commute, a single simultaneous Hamiltonian evolution describes the dynamics, whose terms are the individual gates.
Physical motivation
How can we tell when we have successfully built a quantum computer?Given that tomography quickly becomes difficult as the number of qubits in a system grows, it is pertinent to ask if there is a simpler way of verifying the success of a quantum computation.One way, which has already been attempted in several experiments, e.g.[7,6,8,18], would be to use the prototype quantum computer to find the solution to a problem which we think is difficult to solve on a classical computer.
For instance, the following scenario is generic.Alice is a skeptic, she doesn't believe that Bob has a quantum device at his disposal.Fortunately, she is relatively certain that classical computers can't efficiently find the prime factors of a large integer, whereas quantum computers can [16] (although many qubits may be required for a convincing demonstration).So she issues a challenge to Bob : she chooses a large number for which she cannot find the prime factors and sends it to Bob.If Bob then sends back the prime factors of her number within a reasonable time period, she can easily convince herself that Bob must have had a quantum device at his disposal.This scenario in particular is one which has been used in attempts to verify the success of several small-scale quantum computers [7,6,8], though of course the numbers used were too small to be considered hard to factor classically.Unfortunately, so far as we know, Shor's factoring algorithm is a relatively difficult quantum algorithm to perform.It is well known that it can be implemented in a circuit model using polynomial circuit depth and linear circuit width, or logarithmic depth with a larger width [3], or even with constant depth if arbitrarily wide 'fanout' gates are allowed [4].In either case, we'd apparently require a fully universal set of quantum gates, and more than a thousand logical qubits, for a convincing demonstration.
In this paper, we use abelian dynamics to suggest a two-party protocol (with classical message-passing), which could be used to test remotely a quantum device, which we believe is physically far less complex than factorization.We conjecture that it is classically infeasible to simulate the quantum process in our protocol, and that our protocol is simpler to implement than all known versions of Shor's algorithm, not requiring anything like a universal gate set.
Guide to the paper
We introduce the paradigm IQP, which stands for "Instantaneous Quantum Polytime".It is a restricted model of quantum computation, which can also be thought of in terms of an oracle for computation.Here 'polytime' means that the process is bound to consume at most a polynomial amount of resource in any reasonable model of quantum computation, while 'instantaneous' means that the algorithmic process itself is to contain no inherent temporal structure.We give formal definitions, and argue that there are non-trivial applications for IQP.In particular, a two-party interactive protocol game is described and discussed.These are our main points, to bear in mind throughout the paper :
• We define a restricted model of quantum computation, called IQP (section 2).
• We present several different quantum architectures (section 5) that can render computations in the IQP model, suggesting that it is a 'lowest common denominator' of some 'natural' ideas for computing based on 'abelian' notions.• Although we know of no specific architecture where the Hamiltonians and measurements involved in the IQP paradigm really are genuinely 'easy' to implement, nonetheless there is a clear sense in which the mathematics that underlies the computation is 'easy'.Perhaps the "Graph State" architecture (section 5) gives the clearest example of a practical computing idea.• We argue and conjecture that the probability distributions generated in the IQP paradigm (section 2) are not only classically hard to sample from approximately, but that there are actual polynomial-time protocols (section 3) that can be completed using an IQP oracle that (we believe) can't be completed classically in polynomial time.
• We provide an explicit example of such a protocol, involving two parties.The purpose of the protocol is simply for one party to prove to the other that they are capable of approximating a multi-qubit output distribution having characteristics that match the output distribution of a particular IQP process.In the protocol, Alice designs a problem with a 'hidden' property, and sends it to Bob; Bob runs the problem through his IQP oracle several times, and sends the classical outputs back to Alice; Alice then uses the secret 'hidden' property to assess whether there is good evidence for Bob having used a real IQP oracle.This is all done in section 3. • We make a pragmatic analysis of our suggested protocol, showing how to fine-tune its parameters in order to make plausible the conjecture that it really can't be 'faked' classically (section 4).• By analogy, this protocol is to quantum computation what Bell experiments are to quantum communication : the simplest known 'proof' of a distinctly quantum phenomenon.(Of course, since there is no mathematical proof published to date of a separation between the power of quantum computation and classical computation, we still have to rely on certain computational hardness conjectures.)• Despite the existence of protocols apparently requiring an IQP oracle, we are unable to find any decision language in BPP IQP that is not in BPP.There seems to be a sense in which the paradigm isn't able to 'compute new information' (section 4).
• If there should one day be architectures that can implement IQP oracles-even though full-blown universal quantum computing remain an unresolved engineering challenge-then our protocol may be an important demonstrator of the power of quantum mechanics for quantum computing.
Much of the mathematics used depends significantly on the theory of binary matroids and binary linear codes, and so we spend some time in section 2 recalling some basic definitions.Readers interested in the main construction (the interactive game) should start at section 3 and dip back into the earlier definitions where needed.Pure mathematicians might prefer to start at section 3.3.3;cryptographers might particularly appreciate section 4; whereas physicists may prefer section 5.
The IQP paradigm
In this section, we define what we call the "X-program" architecture, and use it to define the notion of IQP oracle.The rest of the paper depends heavily on these definitions.Note that the X-program architecture is not particularly 'physical', but is easier to work with than the more physically relevant architectures discussed in section 5.
X-programs
Recall that a Pauli X operator acts on a single qubit, exchanging
| 0 with | 1 , i.e. X = | 0 1 | + | 1 0 |. One can also think of X as a Hamiltonian term, since X ∝ exp(i π 2 X
).An X-program is essentially a Hamiltonian that is a sum of products of Xs acting on different qubits.
In this architecture, allow for a set of n qubits, initialised into the pure separable computational basis state | 0 .The X-program is specified as a (polysize) list of pairs (θ p , p) ∈ [0, 2π] × n 2 , so θ p is an angle and p is a string of n bits.Each such program element (pair) is interpreted as the action of a Hamiltonian on the qubits indicated by p, applied for action1 θ p : the Hamiltonian to apply is made up from a product of Pauli X operators on the indicated qubits, and naturally these all commute.This means that-in principle-the program elements could all be applied simultaneously : their time ordering is irrelevant.The measurement to be performed, once all the Hamiltonians have been applied, is simply a computational-basis measurement, and the program output is simply that measurement result, regarded as a (probabilistic) sample from the vectorspace n 2 .Combining this together, we see that the probability distribution for such an output is
È(X = x) = x | exp p iθ p j:p j =1 X j | 0 n 2 .
(
)1
The output string here is labelled x.The random variable X here (and throughout) codifies this probability distribution of classical output samples.
For almost all of our purposes, we are only interested in the case where the θ p action values are the same for every term.When that condition applies, and the value θ is specified, the entire X-program can be represented using a poly(n)-by-n binary matrix, with each row corresponding to a term in the Hamiltonian.For example, the 7-by-4 binary matrix
P = 1 0 0 0 1 1 0 0 0 1 1 0 1 0 1 1 0 1 0 1 0 0 1 0 0 0 0 1 (2)
would represent the 4-qubit Hamiltonian
H P,θ = θ • (X 1 + X 1 X 2 + X 2 X 3 + X 1 X 3 X 4 + X 2 X 4 + X 3 + X 4 ).(3)
IQP oracle
Definition 1 On input the explicit description of an X-program, we define an IQP oracle to be any computational method that efficiently returns a sample string from the probability distribution as given at line (1).
For a formal definition of what is meant by an IQP oracle, let it be any device that interfaces to a probabilistic Turing machine via an 'oracle tape', so that if the oracle tape holds a description of a particular X-program (P, θ in the 'constant action' case) at the time when the Turing machine calls its 'implement oracle' instruction, then in unit time (or perhaps in time polynomial in the length of the description of P , i.e. polynomial in n), a bitstring sample in n 2 from the probability distribution at line (1) is created and written to the oracle tape, and control is passed back to the Turing machine to continue processing.We write the overall paradigm-of classical computation augmented by this oracle-as BPP IQP , to denote the fact that classical randomised polytime pre-and post-processing is usually to be considered allowed in a simulation, and to denote the fact that we don't much care which of several quantum architectures might be being used to supply the 'IQPpower' of sampling from probability distributions of the form at line (1).This notation is not necessarily supposed to indicate a particular class of decision languages as such, but rather a particular class of computations.The interactive proof games in section 3 require the Prover to have access to an IQP oracle, and to access it a polynomial number of times, though these calls may be made in parallel and without precomputation.
Lemma 1
The probability distribution given at line (1) is equivalent to the one given below.
È(X
= x) = a : a•P =x p : ap=0 cos θ p p : ap=1 i sin θ p 2 . (4)
Proof : Let P denote the k-by-n binary matrix whose rows are the p vectors of the X-program under consideration.Then using the fact that the Hamiltonian terms in an X-program all commute, we can think of the quantum amplitudes arising in an X-program implementation as a sum over paths,
x | p cos θ p + i sin θ p j:p j =1 X j | 0 n = x | a∈ k 2 p : ap=0 cos θ p p : ap=1 i sin θ p n j=1 X (a•P ) j j | 0 n ,(5)
and hence derive a new form for the probability distribution accordingly.
Binary matroids and Linear binary codes
Before proceeding to the main topics of the paper, it behooves us to establish the link that these formulas have with the (closely related) theories of binary matroids and binary linear codes.
Definition 2 A linear binary code, C, of length k is a (linear) subspace of the vectorspace k 2 , represented explicitly.The elements of C are called codewords, and the Hamming weight wt(c) ∈ [0..k] of some c ∈ C is defined to be the number of 1s it has.The rank of C is its rank as a vectorspace.
Linear binary codes are frequently presented using generator matrices, where the columns of the generator matrix form a basis for the code.If P is a generator matrix for a rank r code C, then P has r columns and the codewords are {P • d T : d ∈ r 2 }.There are many different, isomorphic, definitions for matroids, [10].We shall adopt the following definition.
Definition 3 A k-point binary matroid is an equivalence class of matrices defined over
2 , where each matrix in the equivalence class has exactly k rows, and two matrices are equivalent (written M 1 ∼ M 2 ) when for some (k-by-k) permutation matrix Q, the columnechelon reduced form of M 1 is the same as the column-echelon reduced form of Q • M 2 .Here we take column-echelon reduction to delete empty columns, so that the result is full-rank.Hence the rank of a matroid is the rank of any of its representatives.
Less formally, this means that a binary matroid is like a matrix over 2 that doesn't notice if you rearrange its rows, if you add one of its columns into another (modulo 2), or if you duplicate one of its columns.This means that a matroid is like the generator matrix for a linear binary code, but it doesn't mind if it contains redundancy in its spanning set (i.e. has more columns than its rank) and it doesn't care about the actual order of the zeroes and ones in the individual codewords.To be clear, when thinking of a matrix such as P in line (2), we are simultaneously thinking of its columns as the elements of a spanning set for a code, and its rows as the points of a corresponding matroid.Because one cannot express a matroid independently of a representation, we consistently conflate notation for the matrix P with the matroid P that it represents.Perhaps the main structural feature of a binary matroid is its weight enumerator polynomial.
Definition 4 If the k rows of binary matrix P establish the points of a k-point matroid, then the weight enumerator of the matroid is defined to be the weight enumerator of the k-long code C spanned by the columns of P , which in turn is defined to be the bivariate polynomial
W EP C (x, y) = c∈C x wt(c) y k−wt(c) .(6)
This is well-defined, because the effect of choosing a different matrix P that represents the same binary matroid simply leads to an isomorphic code that has the same weightenumerator polynomial as the original code C.
Bias in probability distributions
Definition 5 If X is a random variable taking values in n 2 , and s is any element of n 2 , then the bias of X in direction s is simply the probability that X • s T is zero, i.e. the probability of a sample being orthogonal to s.
Let us now consider an X-program on n qubits that has constant action value θ, whose Hamiltonian terms are specified by the rows of matrix P , as discussed earlier.Then we can use lemma 1 to obtain the following expression of bias, for any binary vector s ∈ n 2 :
È(X • s T = 0) = x : x•s T =0 a : a•P =x (cos θ) k−wt(a) (i sin θ) wt(a) 2 .(7)
Since it would obviously be nice to interpret this expression as the evaluation of a weight enumerator polynomial, we are led to define P s to be the submatrix of P obtained by deleting all rows p for which p • s T = 0, leaving only those rows for which p • s T = 1.We call 2 the number of rows remaining n s .This in turn leads to the code C s being the span of the columns of P s , and likewise a submatroid 3 is correspondingly defined.
Theorem 1 When considering constant-action X-programs, the bias expression È(X•s T = 0) for the random variable X introduced at line (1) depends only on the action value θ and (the weight enumerator polynomial of ) the n s -point matroid P s , as defined above.Moreover, if C s is a binary code representing the matroid P s , then the following formula 4 expresses the bias :
È(X • s T = 0) = c∼Cs cos 2 θ(n s − 2 • wt(c)) .(8)
Proof : See the appendix for a proof.
2 ns is here being used for the length of the code Cs in deference to the usual practice of reserving the letter n for code lengths.This ns is counting a number of rows, and should not be confused with the n used earlier for counting a number of columns.
3 also called a matroid minor 4 Subscripts on expectation operators indicate a variable ranging uniformly over its natural domain.
To recap, this means that if we run an X-program using the action value θ for all program elements, then the probability of the returned sample being orthogonal to an s of our choosing ('orthogonal' in the 2 sense of having zero dot-product with s) depends only on θ and on the (weight enumerator polynomial of the) linear code obtained by writing the program elements p as rows of a matrix and ignoring those that are orthogonal to s.
There is a definition in the literature for weighted matroids, which in this context would correspond to allowing different θ values for different terms in the Hamiltonian of an Xprogram.While mathematically (and physically) natural, such considerations would not help with the clarity of our presentation.
We emphasise at this point the value of theorem 1 : it means that for any direction s ∈ n 2 , the bias of the output probability distribution from an X-program (P, θ) in the direction s depends only on θ and the rows of P that are not orthogonal to s, and not at all on the rows of P that are orthogonal to s.Moreover, the bias in direction s depends only on the matroid P s , and not on the particular matrix P s that represents it.That is, directional bias (definition 5) is a matroid invariant.
Note that whenever A is an n-by-n invertible matrix over 2 , then p
• s T = p • A • A −1 • s T = (p • A) • (s • A −T ) T ,
so any invertible column operation on matrix P accompanies an invertible change of basis for the set of directions of which s is a member.Note also that appending or removing an all zero column to P has the effect of including or excluding a qubit on which no unitary transformations are performed.Thus if P s is a submatroid of P by point-deletion, as described earlier, then if the invertible column transformation A is applied to the matrix P that represents the matroid P , then the same matroid that was formerly called P s is still a submatroid, but now it is represented by the matrix P s•A −T .Likewise, appending or removing a column of zeroes to P necessitates an extra zero be appended or removed from any s that serves as a direction for indicating a submatroid.This is purely an issue of representation, and we consider that intuition about these objects is aided by taking an 'abstractist' approach to the geometry.
Entropy, and trivial cases
Because it will be useful later, we will define the Rényi entropy (collision entropy) of a random variable, before exemplifying theorem 1 and proceeding with the main construction of the paper.
Definition 6
The collision entropy, S 2 , of a discrete random variable, X, measures the randomness of the sampling process by measuring the likelihood of two (independent) samples being the same.It is defined by
2 −S 2 = x È(X = x) 2 = s 2È(X • s T = 0) − 1 2 . (9)
And so there are a few 'easy cases' for our X random variable of lemma 1 that should be highlighted and dismissed up front :
Lemma 2 For a constant-action X-program, if θ is. . .
• . . .a multiple of π, then the returned sample will always be 0. The collision entropy will be zero.• . . .an odd multiple of π/2, then the returned sample will always be p∈P p.The collision entropy is zero.• . . .an odd multiple of π/4, then the collision entropy need not be zero, but the probability distribution will be classically simulable to full precision.
Proof : In the first case, considering line (4), there is then a sin(π) = 0 factor in every term of the probability, except where x = 0.
In the second case, considering again line (4), there is then a cos(π/2) = 0 factor in every term, except where all the p vectors are summed together to give x.The same can also be deduced from theorem 1, which implies that x will be surely orthogonal to s exactly when n s is even, i.e. exactly when an even number of rows of P are not orthogonal to s, i.e. exactly when p∈P p is orthogonal to s.
For the third case, if θ is an odd multiple of π/4, then all the gates in the program would be Clifford gates.By the Gottesman-Knill theorem there is then a classically efficient method for sampling from the distribution, by tracking the evolution of the system using stabilisers, etc.
For other sufficiently different values of the action parameter, classical intractibility becomes a plausible conjecture (cf.[15,14]).In particular, the remainder of this paper will specialise to the case θ = π/8, since we are able to make all our points about the utility of IQP even with this restriction.
Interactive protocol
One would naturally like to find some 'use' for the ability to sample from the probability distribution that arises from a temporally unstructured quantum polytime computation; a 'task' or 'proof' that can be completed using e.g. an X-program, which could not be completed by purely classical means.In this section we develop our main construction; a two-player interactive protocol game in which a Prover uses an IQP oracle simply to demonstrate that he does have access to an IQP oracle.
At a glance
There are three aspects of design involved in specifying an actual "Alice & Bob" game :
A) a code/matroid construction, for Alice to select a problem, to send to Bob, B) an architecture or technique by which Bob to take samples from the IQP distribution of the challenge he receives, to send back to Alice, A') an hypothesis test for Alice to use to verify (or reject) Bob's attempt.
We have already defined the X-program architecture, and in section 5 we discuss some alternatives that Bob might like to try.In section 4 we make an analysis of some classical cheating strategies for Bob, in case he can't lay his hands on a quantum computer.The details of precisely how to make a good hypothesis test are omitted from this paper for the sake of brevity, but sourcecode is available on our website (see section 3.4).
Alice plays the role of the Challenger/Verifier, while Bob plays the role of the Prover.Alice uses secret random data to obfuscate a 'causal' matroid P s inside a larger matroid P , and the latter she publishes (as a matrix) to Bob. Bob interprets matrix P as an X-program to be run several times, with θ = π/8.He collects the returned samples, and sends them to Alice.Alice then uses her secret knowledge of 'where' in P the special P s matroid is hidden, in order to run a statistical test on Bob's data, to validate or refute the notion that Bob has the ability to run X-programs.
This application is perhaps the simplest known protocol, requiring (say) ∼ 200 qubits, that could be expected to convince a skeptic of the existence of some computational quantum effect.The reason for this is that there seems to be no classical method to fake even a classical transcript of a run of the interactive game between Challenger and Prover, without actually being (or subverting the secret random data of) the classical Challenger.
Concept overview
Consider therefore the following game, between Alice and Bob.Alice, also called the Challenger/Verifier, is a classical player with access to a private random number generator.Bob, also called the Prover, is a supposedly quantum player, whose goal is to convince Alice that he can access an IQP oracle, i.e. run X-programs.The rules of this game are that he has to convince her simply by sending classical data, and so in effect Bob offers to act as a remote IQP oracle for Alice, while Alice is initially skeptical of Bob's true IQP abilities.
Alice's challenge
The game begins with Alice choosing some code C s that has certain properties amenable to her analysis.She chooses the code C s in such a way that there is a θ for which the (quantum) expectation value at line (8) of theorem 1 is somewhere well within ( 1 2 , 1), and for which the corresponding expectation value that arises from the best-known classical approaches to 'cheating' (e.g.presumably the one at line (20) of section 4.4, in case θ = π/8) is significantly smaller.She then finds a matrix P s whose columns generate the code (not necessarily as a basis), and ensures that there is some s that is not orthogonal to any of the rows of P s .The vector s should be thought of not as a structural property of the code C s , but as a 'locator' that can be used to 'pinpoint' P s even after is has later been obfuscated.Obfuscation of P s is achieved by appending arbitrary rows that are orthogonal to s.This gives rise to matrix P .The matroid P has P s as a submatroid, in the sense that removal of the correct set of rows will recover P s .Alice publishes to Bob a representation of matroid P that hides the structure that she has embedded.Random row permutations are appropriate, and reversible column operations likewise leave the matroid invariant (though the latter will affect s and must therefore be tracked by Alice).
Bob's proof
Bob, being BPP IQP -capable by hypothesis, may interpret the published P as an Xprogram, to be run with the (constant) action set to θ = π/8 (say).He will be able to generate random vectors which independently have the correct bias in the (unknown to him) direction s, i.e. the correct probability of being orthogonal to Alice's secret s, in accordance with theorem 1.Although he may still be entirely unable to recover this s from such samples, he nonetheless can send to Alice a list of these samples as proof that he is BPP IQP -capable.Note that Bob's strategy is error-tolerant, because if each run of the IQP algorithm were to use a 'noisy' θ value, then the overall proof that he generates will still be valid, providing the noise is small and unbiased and independent between runs.Note also that he can manage several runs in one oracle call, if desired, simply by concatenating the matrix P with itself diagonally.That is to say, we even avoid classical temporal structure (adaptive feed-forward) on Bob's part.
Alice's verification
Since Alice knows the secret value s, and can presumably compute the value È(X • s T = 0) from the code's weight enumerator polynomial (see theorem 1 and recall that she is free to choose any C s that suits her purpose), it is not hard for her to use a hypothesis test to confirm that the samples Bob sends are commensurate with having been sampled independently from the same distribution that an X-program generates.That is to say, Alice will not try to test whether Bob's data definitely fits the correct IQP distribution, but she will ensure that it has the particular characteristic of a strong bias in the secret direction s.This enables her to test the null hypothesis that Bob is cheating, from the alternative hypothesis that Bob has non-trivial quantum computational power.
This requires belief in several conjectures on Alice's part.She must believe that there is a classical separation between quantum and classical computing; in particular that IQP is not classically efficiently approximately simulable-at least she must believe that Bob doesn't know any good simulation tricks.She must believe that her problem is hard-at least she should believe that the problem of identifying the location of P s within P is not a BPP problem-on the assumption that the matroid P s is known.
If he passes her hypothesis test, Bob will have 'proved' to Alice that he ran a quantum computation on her program, provided she is confident that there is no feasible way for Bob to simulate the 'proof' data classically efficiently, i.e. provided she has performed her hypothesis test correctly against a plausibly best null hypothesis.In particular, Alice should ensure a large collision entropy for the true (IQP) distribution, since she will want to remove all 'short circuits' (i.e.all the empty rows and all the duplicate rows) from Bob's data, before testing it, to make a test that is both fair and efficient.Otherwise it would be too easy for Bob to generate a set of data that has a strong bias in very many directions simultaneously; and it would be tedious for Alice to confirm that he has not cheated in this way if she did not remove the short circuits.
Significance
This kind of interactive game could be of much significance to validation of early quantum computing architectures, since it gives rise to a simple way of 'tomographically ascertaining' the actual presence of at least some quantum computing, modulo some relatively basic complexity assumptions.In this sense it is to quantum computation what Bell violation experiments are to quantum communication. 5f course, this protocol really comes into its own when the architecture being tested happens to have the undesirable engineering feature of being unable to sustain long-term quantum coherence, and therefore perhaps only ever being capable of shallow-depth computation.Unfortunately, the prescription for X-programs given in section 2 requires Hamiltonian terms that act across potentially hundreds of qubits, and the alternative architectures discussed in section 5 have similar physical drawbacks that still make this paradigm extremely challenging for today's engineering.
Note that this 'testing concept' does not use the IQP paradigm to compute any data that is unknown to everyone, nor does it directly provide Bob with any 'secret' data that could be used as a witness to validate an NP language membership claim.Its only effect is to provide Bob with data that he can't use for any purpose other than to pass on to Alice as a 'proof' of IQP-capability.It is an open problem to find something more commonly associated with computation-perhaps deciding a decision language, for example-that can be achieved specifically by the BPP IQP paradigm.
Recommended construction method
Here is a specific example of a construction methodology (with implicit test methodology) for Alice, which we conjecture to be asymptotically secure (against cheating Prover) and efficient (for both Prover and Verifier).
Recipe for codes
The family of codes that we suggest Alice should employ within the context of the game outlined above are the quadratic residue codes.These will be shown to have the significant property that there is a non-negligible gap between the quantum-and best-known-classicalapproximation expectation values for the bias in the secret direction, both of which are significantly below 1. (The bias for a truly quantum-enabled Bob has already been defined in theorem 1, in terms of the weight-enumerator polynomial of the causal code.For a classically cheating Bob, we discuss the best-known classical strategies and their biases in section 4.4.)Consider a quadratic residue code over 2 with respect to the prime q, chosen so that q + 1 is a multiple of eight.The rank of such a code is (q + 1)/2, and the length is q.A quadratic residue code is a cyclic code, and can be specified by a single cyclic generator.There are several ways of defining these, but the simplest definition is to take the codeword that has a 1 in the jth place if and only if the Legendre symbol6 j q equals 1, i.e. if and only if j is a non-zero quadratic residue modulo q.
For example, if q = 7 (the smallest example) then the non-zero quadratic residues modulo q are {1, 2, 4}, and so the quadratic residue code in question is the rank-4 code spanned by the various rotations of the generator (0, 1, 1, 0, 1, 0, 0, 0) T .A basis for this code is found in the columns of the matrix at line (2).
Lemma 3 When q is a prime and 8 divides q + 1, then there is a unique quadratic residue code C (up to isomorphism) of length q over 2 , having rank (q + 1)/2, and it satisfies
c∼C cos 2 π 8 (q − 2 • wt(c)) = cos 2 (π/8) = 0.854 . . .(10)
Moreover, it also satisfies
È c T 1 • c 2 = 0 | c 1 , c 2 ∼ C = 3/4 = 0.75, (11)
which is relevant to certain classical strategies (section 4.4).
Proof : The proof of the rank of the code and its uniqueness are well established results from classical coding theory [22].Other classical results of coding theory include that quadratic residue codes are a parity-bit short of being self-dual and doubly even.That is, the extended quadratic code, with length q + 1, obtained by appending a single parity bit to each codeword, has every codeword weight a multiple of 4 and every two codewords orthogonal.
For line (10) this means that the (unextended) code has codeword weights which, modulo 4, are half the time 0 and half the time −1.On putting these values into the left side of the formula, we immediately obtain the right side.For line (11) this means that in the (unextended) code, any two codewords are non-orthogonal if and only if they are both odd-parity, which happens a quarter of the time : from which the formula follows.
The corollary here is that if Alice uses one of these codes for her 'causal' C s , then if Bob runs a series of X-programs (with constant θ = π/8) described by the (larger) matrix P , the data samples he recovers should be orthogonal to the hidden s about 85.4% of the time (cf.theorem 1); whereas if Bob tries to cheat using the classical strategy outlined in section 4, then his data samples will tend to be orthogonal to the hidden s only about 75% of the time (cf.lemma 6).Alice's hypothesis test therefore basically consists in measuring this single characteristic, after having filtered duplicate and null data samples from Bob's dataset.We would conjecture that Bob has no pragmatic way of boosting these signals, at least not without feedback from Alice, or exponential resources.
Note that with exponential time on his hands, Bob could choose to simulate classically an IQP oracle, in order to obtain a dataset with a bias in direction s that is approximately 85.4%.Alternatively, he could consider every possible s in turn, and test to see whether the matroid obtained by deleting rows orthogonal to his guess is in fact correspondent to a quadratic residue code, assuming he knew that this had been Alice's strategy.
Recipe for obfuscation
Having chosen q as outlined above, and constructed a q-by-(q+1)/2 binary matrix generating a quadratic residue code, Alice needs to obfuscate it.The easiest way to manage this process is not to start with a particular secret s in mind, but rather to recognise the obfuscation problem as a matroid problem, proceeding as follows :
• Append a column of 1s to the matrix : this does not change the code spanned by its columns since the all-ones (full-weight) vector is always a codeword of a quadratic code.Other redundant column codewords may also be appended, if desired.• Append many (say q) extra rows to the matrix, each of which is random, subject to having a zero in the column lately appended.This gives rise to a 2q-point matroid, and ensures that there now is an s such that the causal submatroid (quadratic residue matroid) is defined by non-orthogonality of the rows to that s. • Reorder the rows randomly.This has no effect on the matroid that the matrix represents, nor on the hidden causal submatroid.Nor does it affect s, the 'direction' in which the sumbatroid is hidden.• Now column-reduce the matrix.There is no (desirable) structure within the particular form of the matrix before column-reduction, nothing that affects either codes or matroids.Echelon-reduction provides a canonical representative for the overall matroid, while stripping away any redundant columns that would otherwise cost an unnecessary qubit, when interpreted as an X-program.By providing a canonical representative, it closes down the possibility that information in Alice's original construction of a basis for her causal code might leak through to Bob, which might be useful to him in guessing s.Rather more importantly, this reduction actually serves to hide s. (We can be sure by zero-knowledge reasoning that this hiding process is random : echelon reduction is canonical and therefore supervenes any column-scrambling process, including a random one.)• Finally, one might sort the rows, though this is unnecessary.The resulting matrix is the one to publish.It will have at least (q + 1)/2 columns, since that is the rank of the causal submatroid hidden inside.
Mathematical problem description
This method of obfuscation amounts to-mathematically speaking-a situation whereby for each suitable prime q, we start by acknowledging a particular (public) q-point binary matroid Q, viz the one obtained from the QR-Code of length q.Then an 'instance' of the obfuscation consists of a published 2q-point (say) binary matroid P , and there is to be a hidden "obfuscation" subset O such that Q = P \O; and the practical instances occur with P chosen effectively at random, subject to these constraints.(One could choose to make O bigger than q points if that were desired.)This has the feel of a fairly generic hidden substructure problem, so it seems likely that it should be NP-hard to determine the location of the hidden Q, given P and the appropriate promise of Q's existence within.
More syntactically, we should like to prove that it is NP-complete to decide the related matter of whether or not P is of the specified form, given only a matrix for P .Clearly this problem is in NP, since one could provide Q in the appropriate basis as witness.We conjecture this problem to be NP-complete.
Conjecture 1 The language of matroids P that contain a quadratic-residue code submatroid Q by point deletion, where the size of Q is at least half the size of P , is NP-complete under polytime reductions.
These sorts of conjecture are apparently independent of conjectures about hardness of classical efficient IQP simulation, since they indicate that actually identifying the hidden data is hard, even for a universal quantum computer.Even should this conjecture prove false, we know of no reason to think that a quantum computer would be much better than a classical one at finding the hidden Q, notwithstanding Grover's quadratic speed-up for exhaustive search.
One might compare the structure of conjecture 1 to that of the following important theorem from graph theory :
Proposition 1 The language of graphs G that contain a complete graph K by vertex deletion, where the size of K is at least half the size of G, is NP-complete under polytime reductions.
This is a classic result, see e.g.[11], where the problem in different guises is called 'Clique' and 'Independent Set' and 'Node Cover'.
Challenge
It seems reasonable to conjecture that, using the methodology described, with a QR-code having a value q ∼ 500, it is very easy to create randomised Interactive Game challenges for BPP IQP -capability, whose distributions have large entropy, which should lead to datasets that would be easy to validate and yet infeasible to forge without an IQP-capable computing device (or knowledge of the secret s vector).We propose such challenges as being appropriate 'targets' for early quantum architectures, since such challenges would essentially seem to be the simplest ones available (at least in terms of inherent temporal structure and number of qubits) that can't apparently be classically met.
Accordingly, we have posted on the internet (http://quantumchallenges.wordpress.com) a $25 challenge problem, of size q = 487, to help motivate further study.This challenge website includes the source code (C) used to make the challenge matrix, and also the source code of the program that we will use to check candidate solutions, excluding only the secret seed value that we used to randomise the problem.
Heuristics
Next we address in more detail the reasons for thinking the problem classically intractable, and also give an accounting of our failure to find a decision language for proving the worth of IQP.
Hardness of strong simulation
In support of the supposed complexity of this paradigm, Terhal and Divincenzo [19], and Aaronson [1], have already showed that it is PP-complete to strongly simulate the generic probability distributions that arise hence.
Lemma 4 It is P GapP -hard to determine the numerical value of È(X = 0) (as defined in section 2, line ( 1)) to within exponential precision, for arbitrary matroids.
Proof : Let Ker L (P ) = {a T : a•P = 0} denote the linear code for which P is a parity-check matrix, and note from line (4) and definition 4 that the probability in question is a function of the weight-enumerator polynomial of this code.Specifically,
È(X = 0) = W EP Ker L (P ) ( cos θ, i sin θ ) 2 . (12)
By varying θ over the range (0, π/2), accurate values of È(X = 0) would enable the recovery of the (integral) coefficients of the weight-enumerator polynomial of Ker L (P ), which by choice of P may be set to be any appropriately sized linear binary code we please.The recovery of arbitrary weight-enumerator polynomials is P GapP -hard [21].
Background
There has been a wide range of work into discovering restricted models of quantum computation which are classically simulable.For example, quantum circuits generating limited forms of entanglement, with classical simulations based on analysing matrix product states or contracting tensor networks; these circuits have a particularly constrained 'circuittopology', which leads to their simplicity (see [9] for a summary of known results).There is no particular circuit-topology imposed in our Z-network architecture (discussed in section 5), so it seems unlikely that the same methods would apply here.Other positive classical simulability results include the stabiliser circuits of the Gottesman-Knill theorem and various matchgate constructions (see [20,5,15,14] and references therein).These constructions differ significantly from our Z-networks in terms of the underlying algebra, the group generated by the set of allowable gates.
Høyer and Spalek [4] have shown that Shor's algorithm for Integer Factorisation can indeed be performed within a constant number of timesteps on a Graph State processor (discussed in section 5), though their constructions offer no reason to believe that that constant might be smaller than, say, ∼ 100; and of course, a general methodology for reducing the inherent time-complexity of oracle-dependent quantum search algorithms is known to be impossible, due to lower bounds on Grover's algorithm.Dan Browne [2] wrote about CDdecomposability, which is the first rigorous treatment that we know of that explicitly links Graph State temporal depth with commutativity of Hamiltonian terms used to simulate a Graph state computation.
Dan Simon [17] wrote about algorithms that use nothing more than an oracle and a Hadamard transform, and which therefore could be described as 'temporally unstructured'.However, his notion of 'oracle' was one tailored for a universal quantum architecture, being essentially an arbitrarily complex general unitary transformation, and since there is no natural notion of one of these within our 'temporally unstructured' paradigm, there is no real sense in which Simon's algorithm can count as an example of an algorithm within the BPP IQP framework.In particular, Simon's oracle implements a unitary that does not commute with the Hadamard transform.
Conjectures, implicit and explicit
It is possible to form various hardness conjectures about the classical simulation of these IQP probability distributions.For a randomly chosen X-program P of a given width n, it seems likely that the associated IQP distribution would be exponentially close to flat random.Conditioned on its not being random, there is no particular reason to think it would be approximately efficiently classically samplable.Here is an example of one such conjecture, though the precise details are not important to our arguments.
Conjecture 2 There exists a distribution D on the set of X-programs, for which no classical Turing machine can gain a non-negligible Ω(1/poly) advantage in deciding whether or not the distribution associated to an X-program chosen randomly from D is exponentially close in trace distance to the uniform distribution.
This particular hardness conjecture is not quite what we really require, but it gives an example of a plausible conjecture about classical simulation, and implies that for almost any X-program of interest, there is a certain event (subset of output possibilities) whose probability will (probably) be estimated wrongly by your favourite classical polynomial-time event-probability-estimating device.(Many similar conjectures sound equally plausible, in an area where almost nothing is known for sure.)The point to emphasise in context of our two-player interactive protocol games is that it is not unreasonable for Alice to believe that Bob can have no classical cheating strategy so long as none such has been published nor proven to exist; and so our protocol may still serve as a demonstration (if not a proof) of a genuinely quantum computing phenomenon, despite the lack of proof of any simulation conjecture.
Another conjecture implicit in Alice's ability to make a fair hypothesis test-so that Bob will indeed have a good chance of passing the test when he does have an IQP oracle (or approximate version of one), but will stand little chance of faking a proof if relying on guesswork and (known) classical techniques-is one that ensures that Alice's X-programs really do incorporate a non-negligible amount of entropy.Although we have little to go on besides scant simulation evidence from small examples, we want to make a conjecture that collision entropy is close to maximal within at least one relevant family of random constant-action X-programs.
Conjecture 3
The expected collision entropy of the probability distribution of a randomly selected X-program of width n, with constant action π/8, scales as n − O(1) with the size of the program.
This conjecture is perhaps not directly relevant to the 'hardness' of the IQP paradigm itself, but merely relevant to our game construction.Note, for example, that since arbitrary-or random-obfuscation rows are used in the construction of the matrix P in the construction of section 3, it follows that there will be much about the random variable X that is arbitrary-or 'typical' in some vague sense-to the point that if one were sure that the only structure of significance were the hidden 'causal' code C s , one could hope to approximate the distribution for X, using knowledge of s, by sampling uniformly at random (no biases) and applying a post-filter to create a bias in direction s of the required strength.This gives some context for conjecture 3.
Classical approximations
Rather than speculate at this stage on which of the very many possible conjectures may or may not be true, we instead turn back to an examination of the mathematical structures underpinning the probability distributions in question.
Suppose we wish to construct a probability distribution that arises from some purely classical methods, which can be used to approximate our IQP distribution.Our motivation here is to check whether any purported application for an IQP oracle might not be efficiently implemented without any quantum technology.We proceed using the relatively ad hoc methods of linear differential cryptanalysis.
Directional derivatives
For the case θ = π/8, we will need to consider only second-order derivatives.The same sort of method will apply to the case θ = π/2 d+1 using dth order derivatives, but the presentation would not be improved by considering that general case here.
In terms of a binary matrix/X-program P , proceed by defining
f : n 2 → /16 , f (a) ≡ p∈P (−1) p•a T (mod 16),(13)
and notate discrete directional derivatives as
f d (a) ≡ f (a) − f (a ⊕ d) (mod 16).(14)
Consider also the second derivatives of f , given by
f d,e(
each of which is quite patently a linear function in the bits (a 1 , . . ., a n ) of a, as a function with codomain the ring /16 , regardless of the choice of directions d, e.
Lemma 5 With f defined as per line (13), and X the random variable of lemma 1, for all s,
È(X • s T = 0) = a cos 2 π 8 • f s (a) ,(16)
and so the IQP probability distribution (in the case θ = π/8) may be viewed as a function of f rather than as a function of P .
Proof : Starting from the proof of theorem 1, line (28),
È(X • s T = 0) = 1 2 1 + a e iθ P p (−1) p•a T 1−(−1) p•s T = 1 2 1 + a exp iπ 8 f (a) − f (a ⊕ s) = 1 2 1 + a cos π 8 • f s (a) . (17)
The second line above is obtained immediately from the first, using the definition of f .The third line follows because the expression is real-valued.The conclusion follows from a basic trigonometric identity, and linearity of the expectation operator.
And so if there is a hidden s such that È(X • s T = 0) = 1, then that implies f s (a) ≡ 0 (mod 16) for all a.This is essentially a non-oracular form of the kind of function that arises in applications of Simon's Algorithm [17], with s playing the role of a hidden shift.One could find linear equations for such an s if it exists, because it would follow immediately that f d,e (s) = f d,e (0) for any directions d, e, which is by line ( 14) equivalent with
p∈P d ∩Pe p • s T = 0. (18)
Classical sampling
To make use of this specific second-order differential property, we need to analyse the probability distribution that a classical player can generate efficiently from it.Proceed by defining a new probability distribution for a new random variable Y, as follows :
È(Y = y) = È d,e p∈P d ∩Pe p = y .(19)
This may be classically rendered, simply by choosing d, e ∈ n 2 independently with a uniform distribution, and then returning the sum of all rows in P that are not orthogonal to either d or e.
Lemma 6
The classical simulable distribution on the random variable Y defined in line (19) satisfies
È(Y • s T = 0) = È c T 1 • c 2 = 0 | c 1 , c 2 ∼ C s (20) = 1 2 1 + 2 −rank( P T s • Ps ) ,(21)
and so the bias of Y in direction s is a function of the matroid P s .
Proof : Starting from line (19), The wedge operator ∧ here denotes the logical AND between binary column-vectors.
È(Y • s T = 0) = y : y•s T =0 È d,
The first line of the lemma follows from the obvious substitutions c
1 = P s • d T , c 2 = P s • e T .
The second line follows because unimodular actions on the left or right of a quadratic form (such as (P T s • P s )) affect neither its rank nor the probabilities derived from it; so it suffices to consider the cases where it is in Smith Normal Form, i.e. diagonal, which are trivially verified.Since this expression is patently invariant under invertible linear action on the right and permutation action on the left of P s , it too is a matroid invariant.
Inter-relation
Thus we have established some kind of correlation between random variables X and Y.
Theorem 2 In the established notation, for X-programs with fixed θ = π/8,
È(X
• s T = 0) = 1 ⇒ È(Y • s T = 0) = 1.
(23) Proof : By theorem 1, the antecedent gives, for all c ∈ C s , n s ≡ 2wt(c) (mod 8), where n s is again the length of the code C s .This entails that every codeword in C s has the same weight modulo 4, including the null codeword, so C s must be doubly even 7 .It is easy to see that doubly even linear codes are self-dual. 8By lemma 6, the consequent is obtained.
The only counterexamples to the converse implication seem to occur in the trivial cases whereby the binary matroid P s has circuits of length 2, i.e.where P s has repeated rows.
Note that if È(X • s T = 0) were equal to 1 precisely, then by making a list of samples from IQP runs, storing them in a matrix, and performing Gaussian Elimination to recover the kernel of the matrix, it would be straightforward to compute the hidden s.However, theorem 2 shows that this is exactly the condition required for being able to compute s via purely classical means.For this reason, it seems hard to find decision languages that plausibly lie in BPP IQP \BPP.
This random variable Y is the 'best classical approximation' that we have been able to find for X. (The intuition is that it captures all of the 'local' information in the function f , which is to say all the 'local' information in the matroid P , so that the only data left unaccounted for and excluded from use within building this classical distribution is the 'non-local' matroid information, which is readily available to the quantum distribution via the magic of quantum superposition.)There seems to be no other sensible way of processing P (or f ) classically, to obtain useful samples efficiently, though it also seems hard to make any rigorous statement to that effect.
Conjecture 4
The classical method defined in this section, yielding random variable Y, is asymptotically classically optimal (when comparing worst-case behaviour and restricting to polynomial time) for the simulation of IQP distributions arising from constant-action θ = π/8 X-programs.
This conjecture lends credence to the design methodology of section 3.
Future work
We might also recommend the further study of matroid invariants through quantum techniques, or perhaps the invariants of weighted matroids, since they seem to be the natural objects of IQP computation as hitherto circumscribed.This would seem to be fertile ground for developing examples of things that only genuine quantum computers can achieve.
Note that if it weren't for the correlation described in theorem 2, then it would be possible to conceive of a mechanism whereby an IQP-capable device could compute an actual secret or witness to something (e.g.learn s), so that the computation wouldn't require two rounds of player interaction to achieve something non-trivial.Yet as it stands, it is an open problem to suggest tasks for this paradigm involving no communication nor multi-party concepts.
Architectures
In this section we sketch two more architectures for implementing IQP oracles.These architectures are probably more physically feasible than X-programs.
Z-networks
The network-or circuit-model of computation is perhaps the most familiar one.Programs for the first architecture we call "Z-networks", since the program is most easily described as a network of gates on an array of qubits, where the allowed gate-set includes just the Controlled-Not gate from any qubit to any qubit and the single-qubit gate that implements the Pauli Z Hamiltonian 9 for some time.Although this Z-network architecture does have a notion of temporal structure-because it is important the order in which the gates of the network are carried out-nonetheless it is useful for our analysis because it turns out to have effectively the same computational power as the X-program architecture under some basic assumptions, and the Lie group structure underpinning the kinds of transformation allowable within the Z-network architecture is particularly easy to work with.On the understanding that n qubits are initialised into | 0 in the computational basis and ultimately measured in the computational basis, it is well known that the gate-set consisting of Controlled-Not gates together with all single-qubit rotations is universal for BQP, and the Lie group generated by this gate-set generates the whole of SU (2 n ), modulo global phase.However, by the term "Z-network" we mean explicitly to limit the single-qubit gates to being those which implement e iθZ for some action θ, so that the Lie group spanned by the gate-set (represented in the computational basis) consists of unitary matrices that are supported by permutation matrices, i.e. those unitaries that have just one non-zero entry per row.Any such unitary can be factored into a diagonal matrix followed by a permutation matrix.(In all cases, global phase is to be regarded as physically irrelevant, and may be 'quotiented out' from the groups in question.)We can describe groups by giving generator sets for them.The group containing all even permutations and all diagonal elements (modulo global phase) is Toffoli, C-Not, X, e iθZ = any even permutation, any diagonal .
This 'qualifies' as a Z-network group; indeed, all Z-network groups are to be a subgroup of this one.But for the purposes of comparison with X-programs and the IQP paradigm, it suffices to consider the much simpler group given by C-Not, X, e iθZ = any linear permutation, any diagonal .
This latter group does not apparently contain (efficiently) the dynamics of classical computation.(The X gate is necessary to enable the construction of all diagonals, but one might prefer to replace implementation of X by the availability of an ancilla | 1 qubit, so that a C-Not gate can simulate an X gate.In the language of complexity theory, (24) might be said to stand in relation to (25) as P stands to L.) One can see how to build a variety of constructions within the group at line (25), using the specified gate-set.E.g. by conjugating e iθZ 1 with two C-Not gates one can create an e iθZ 1 Z 2 composite unitary, and similarly e iθZ 1 Z 2 Z 3 can be created, etc.
Reductions between Z-networks and X-programs
This neat mathematical structure (i.e. as at line (25)) enables probability distributions of the kind at line (1) to be simulated.
Lemma 7 A Z-network can always be designed to simulate an X-program efficiently.
Proof : Simply by initialising the input qubits to the Z-network to | + n in the Hadamard basis, and measuring output in the same Hadamard basis, the simulation of a given Xprogram, P , proceeds by constructing a small network of CNot gates and an exp(iθ p Z) gate for each row p of P .Details omitted for brevity.measurement doesn't matter, because the measurement direction is prescribed rather than adaptive.Hence a sample from n 2 (a bit-string) is thus generated as the total measurement result.
Combining this together, we see that the probability distribution for such an output is
È(X = x) = x | v∈V R v • (u,v)∈E 1 + Z u + Z v − Z u Z v 2 | + n 2 . (26)
Here the measurement has been written using the notation of the computational basis, with an appropriate (passive) rotation immediately prior.
Graph-programs and X-programs
Having described three architectures, we've indicated that the X-programs, characterised by the formulation at line (1), are in some natural sense the 'lowest common denominator' amongst the architectures (and unitary groups) of interest.
Lemma 9 A Graph-program can always be designed to simulate an X-program efficiently.
Proof : Suppose we're given an X-program, written { (θ p , p) : p ∈ P ⊂ n 2 }.Then it is straightforward to simulate it on a Graph State architecture, as follows.Let V be the disjoint union of [1..n] and P , so that the graph state used to simulate the program will have one primal qubit for each qubit being simulated, plus one ancilla qubit for each program element p, the total cardinality of V being polynomial in n, by hypothesis.Let (j, p) ∈ E exactly when the jth component of p is a 1.In this way, the resulting graph is bipartite, linking primal qubits to those ancillae that they have to do with.Let R j be the Hadamard element (H) for all primal qubits, so that all primal qubits are measured in the Hadamard basis.Let R p = exp(iθ p X), so that every ancilla qubit is measured in the (Y Z)-plane at an angle specified by the corresponding program element.
If the resulting Graph-program is executed, it will return a sample vector x ∈ n+#P 2 for which the n bits from the primal qubits are correlated with the #P bits from the ancillae in a fashion which captures the desired output, (though these two sets separately-marginallywill look like flat random data.)To recover a sample from the desired distribution, we simply apply a classical Controlled-Not gate from each ancilla bit to each neighbouring primal bit, according to E, and then discard all the ancilla bits.One can use simple circuit identities to check that this produces the correct distribution of line (1) precisely.
Physical comparison
An X-program uses only 'one timeslice', but presumes an arbitrarily large gatespan (interaction length), up to n, the number of qubits in the X-program.The Z-network reduction is physically preferable because it uses small gates (gatespan = 2) to simulate an X-program.However, it has network depth that is not constant; rather, it is likely to be quadratic in n, in general, unless one is careful to make optimisations when 'compiling' the network.
The Graph-program reduction uses more qubits than n, but has better depth properties than the Z-network architecture.Again, only small gates are used.It seems natural to suggest that the 'true temporal cost' of implementing a Graph program would either be one process for measurement plus either one process or degree processes for initialising the graph state, where degree denotes the vertex-degree of the underlying graph.The number of qubits required in the simulation of an X-program is also slightly larger, since ancilla qubits are used.The worst case in our interactive protocol application would therefore require about 5q/2 qubits, rather than q/2, though the vertex-degree would no bigger than the number of qubits.The kinds of graph called for in our Graph-program reduction are not the usual cluster state graphs (regular planar lattice arrangement) used in measurementbased quantum computation.The bipartite graphs described in the reduction will usually be far from planar for generic X-programs, having a relatively high genus.This means that the graph cannot be 'laid out' on a plane without edges crossing.Here we have used the standard Fourier decomposition of a periodic function, and used the fact that the function is known to be real.The variable substitution at the third line was c = P s •a T , understood in the correct basis.At the fourth line it was w = (2n s − j)/4.
È(X
2 p∈Pe(− 1 )
21
a) ≡ f e (a) − f e (a ⊕ d) (mod 16) ≡ p•a T 1 − (−1) p•d T (mod 16)
=
È d,e wt( P • d T ∧ P • e T ∧ P • s T ) ≡ 0 (mod 2) = È d,e wt( P s • d T ∧ P s • e T ) ≡ 0 (mod 2) = È d,e d • P T s • P s • e T = 0 .
Èe
(X • s T = 0) = 2 n x {x • s T = 0} • È(X = x) = 2 n a,d,x (1 + (−1) x•s T ) 2 (−1) x•d T e iθ P p (−1) p•a T 1−(−1) p•d T p•a T 1−(−1) p•s T .(28)These transformations are conceptually simple but notationally untidy.2• È(X • s T = 0) − 1 = P p (−1) p•a T 1−(−1) p•s T ijθ È ( j = 2( n s − 2 • wt(c) ) | c ∼ C s ) = w cos( 2θ(n s − 2w) ) • È ( w = wt(c) | c ∼ C s ) .(29)
• s T = 0) = ns w=0 cos 2 ( θ(n s − 2w) ) • È ( w = wt(c) | c ∼ C s ) = c∼Cs cos 2 θ(n s − 2 • wt(c)).
action = the integral of energy over time.
We have serendipitously identified a construction for which the probability gap-quantum 85.4% over classical 75%-precisely matches the gap available in Bell's inequalities. See lemma 3.
This Legendre symbol is equivalent, modulo q, to j (q−1)/2 .
Doubly even just means that every codeword has weight a multiple of 4.
Self-duality just means that the dual code-consisting of all words orthogonal to every codeword-is equal to the code.
Z = | 0 0 | − | 1 1 |, on a single qubit.
AcknowledgementsWe would like to thank Tobias Osborne, Richard Jozsa, Ashley Montanaro, Dan Browne, Scott Aaronson, and Richard Low for useful discussions and suggestions.We also acknowledge the support of the EC-FP6-STREP network QICS.Conversely,Lemma 8 An X-program can efficiently simulate a given Z-network, provided that that Znetwork uses Hadamard-basis input, C-Nots, X gates, and e iθZ gates only, and outputs in the Hadamard basis.Proof : The required reduction just associates one X-program element (θ p , p) to each e iθZ gate, setting θ p ← θ and specifying p according to the location of the e iθZ gate and the totality of C-Not gates to the left of that gate.A final piece of simple post-processing is needed after the measurement phase of the X-program, to account for the C-Nots in the Z-network, but this post-processing simply consists in applying the same C-Nots (with directions reversed) on the classical measurement outcomes.(This is because moving from the Hadamard basis to the computational basis has the effect of reversing the direction of C-Not gates.)The point of these reductions is to highlight the sense in which the group associated to simple Z-networks stands in the same relation to the set of X-programs as the 'full' SU (2 n ) Lie group stands to the set of proper full-blown quantum algorithms.Graph-programsPrograms for the second of these architectures we call "Graph-programs", since the program is most easily described as the construction of a graph state followed by a series of measurements of the qubits in the graph state in various bases[2].Graph state computing architectures are popular candidates for scalable fully universal quantum processors[13,12].Here we are concerned not with universal architectures, but with the appropriate restriction to 'unit time' computation.So, unlike universal graph state computation, our Graph-programs do not admit adaptive feed-forward, which is to say that all measurement angles must be known and fixed at compile-time, so that all measurements can be made simultaneously once the graph state has been built.In this sense, the 'depth' of a Graphprogram is 1.A graph state has qubits that are initially devoid of information, but which are entangled together according to the pattern of some pre-specified graph.A graph state can be constructed without inherent temporal complexity, perhaps even prepared in a single computational time-step, because there is no implicit reason requiring one edge of the graph to be prepared before any other.(It is still fair to argue that the circuit-depth of the process that generates a graph state is linear in the valency of the graph, but that is not a measure of 'inherent' temporal complexity.)We will show how Graph-programs can simulate the output of X-programs if a little trivial classical post-processing of the measurement results is allowed.A Graph-program is taken to be an undirected (usually bipartite) graph with labelled and distinguished vertices.The vertex set is denoted V , of cardinality n, and for each v ∈ V there is an element of SU (2) labelling it; R v ∈ SU (2).The edge set is denoted E. To implement the program, a qubit is associated with each vertex and is initialised to the state | + in the Hadamard basis.Then a Controlled-Z Pauli gate is applied between each pair of qubits whose vertices are a pair in E. Since these Controlled-Z gates commute, they may be applied simultaneously, at least in theory.Finally, each vertex qubit v is measured in the direction prescribed by its label R v , returning a single classical bit.Clearly the order of Appendix A proof of theorem 1. Throughout, the variable p ranges over the rows of the binary matrix P , which are the program elements of an X-program.Derive line (8) from line (1) in the case that the value θ is constant.È(X
Quantum computing, postselection, and probabilistic polynomialtime. S Aaronson, arXiv:quant-ph/0412187Proceedings of the Royal Society A. 4612063. 2005
Lectures on quantum information, ch. D E Browne, H J Briegel, arXiv:quant-ph/060322620065
Fast parallel circuits for the quantum Fourier transform, focs. R Cleve, J Watrous, 41st Annual Symposium on Foundations of Computer Science. 2000526
Quantum circuits with unbounded fan-out. P Høyer, R Spalek, arXiv:quant-ph/0208043Theory of Computing. 152005
Matchgates and classical simulation of quantum circuits. R Jozsa, A Miyake, arXiv:0804.40502008
Experimental demonstration of shor's algorithm with quantum entanglement. B P Lanyon, T J Weinhold, N K Langford, M Barbieri, D F V James, A Gilchrist, A G White, arXiv:0705.1398Physical Review Letters. 992505052007
Experimental realization of shor's quantum factoring algorithm using nuclear magnetic resonance. M K Lieven, Matthias Vandersypen, Gregory Steffen, Breyta, S Costantino, Mark H Yannoni, Isaac L Sherwood, Chuang, Nature. 4142001
Demonstration of shor's quantum factoring algorithm using photonic qubits. Chao-Yang Lu, Daniel E Browne, Tao Yang, Jian-Wei Pan, arXiv:0705.1684Phys. Rev. Lett. 992505042007
Simulating quantum computation by contracting tensor networks. I L Markov, Y Shi, arXiv:quant-ph/0511069v62006
J G Oxley, Matroid theory. New YorkOxford University Press1992
Christos H Papadimitriou, Computational Complexity. Addison-Wesley Publishing1994
Measurement-based quantum computation with cluster states. R Raussendorf, 2003Ludwig-Maximillians Universität MünchenPh.D. thesis
A one-way quantum computer. R Raussendorf, H J Briegel, Phys. Rev. Lett. 8651882001
. N Schuch, M M Wolf, F Verstraete, J I Cirac, arXiv:0705.0292Phys. Rev. Lett. 100305042008
On entropy growth and the hardness of simulating time evolution. N Schuch, M M Wolf, K G H Vollbrecht, J I Cirac, arXiv:0801.2078New J. Phys. 10330322008
Algorithms for quantum computation: Discrete logarithms and factoring. P Shor, Proc. 35th Ann. Symp. on Foundations of CS. 35th Ann. Symp. on Foundations of CS1994
On the power of quantum computing. R Daniel, Simon, Siam J. Comp. 2651997
Experimental realization of deutsch's algorithm in a one-way quantum computer. M S Tame, R Prevedel, M Paternostro, P Böhi, M S Kim, A Zeilinger, arXiv:quant-ph/0611186Phys. Rev. Lett. 981405012007
Adaptive quantum computation, constant depth quantum circuits and arthur-merlin games. B M Terhal, D P Divincenzo, arXiv:quant-ph/0205132002
. L Valiant, SIAM J. Computing. 31412292002
Hardness of approximating the weight enumerator of a binary linear code. M N Vyalyi, arXiv:cs/0304044v12003
The theory of error-correcting codes. F J Macwilliams, N J A Sloane, 1996Elsevier ScienceAmsterdam
| [
-0.2139829397201538,
0.02419663593173027,
-0.0641167163848877,
0.055173031985759735,
-0.06235828250646591,
-0.08790422230958939,
-0.11018729954957962,
-0.15855064988136292,
0.12770748138427734,
-0.004508189857006073,
-0.06703191995620728,
-0.14964009821414948,
-0.0054838950745761395,
0.040... |
Anomalous vortex dynamics in spin-triplet superconductor UTe 2
May 30, 2023
Y Tokiwa ytokiwa@gmail.com
Advanced Science Research Center
Japan Atomic Energy Agency
Japan
H Sakai
Advanced Science Research Center
Japan Atomic Energy Agency
Japan
S Kambe
Advanced Science Research Center
Japan Atomic Energy Agency
Japan
P Opletal
Advanced Science Research Center
Japan Atomic Energy Agency
Japan
E Yamamoto
Advanced Science Research Center
Japan Atomic Energy Agency
Japan
M Kimata
Institute for Materials Research
Tohoku University
SendaiMiyagiJapan
S Awaji
Institute for Materials Research
Tohoku University
SendaiMiyagiJapan
T Sasaki
Institute for Materials Research
Tohoku University
SendaiMiyagiJapan
Y Yanase
Department of Physics
Kyoto University
606-8502KyotoJapan
Y Haga
Advanced Science Research Center
Japan Atomic Energy Agency
Japan
Y Tokunaga
Advanced Science Research Center
Japan Atomic Energy Agency
Japan
Anomalous vortex dynamics in spin-triplet superconductor UTe 2
May 30, 2023E2A051EA33AF851D85D387DDD1DA3E36arXiv:2305.17840v1[cond-mat.str-el]
The vortex dynamics in the spin-triplet superconductor, UTe2, are studied by measuring the DC electrical resistivity with currents along the a-axis under magnetic fields along the b-axis.Surprisingly, we have discovered an island region of low critical current deep inside the superconducting (SC) state, well below the SC upper critical field, attributed to a weakening of vortex pinning.Notably, this region coincides with the recently proposed intermediate-field SC state.We discuss the possibility of nonsingular vortices in the intermediate state, where SC order parameter does not vanish entirely in the vortex cores due to the mixing of multiple SC components.
Unconventional superconductivity often leads to an unconventional vortex states.In conventional cases, the thermodynamic superconducting (SC) transition and the formation of vortex lattice occur simultaneously at T c .However, in unconventional superconductors, these could appear sequentially due to their anomalously large T c compared to their condensation energy per coherent volume, leading to the formation of a vortex liquid state in a region below T c [1].Since the lattice constant of vortex continuously decreases with increasing magnetic field, a vortex lattice melts above a magnetic field close to B c2 , when the amplitude of vortex lattice fluctuations becomes comparable to the lattice constant [1].
Among heavy fermion compounds, URu 2 Si 2 and UCoGe exhibit unusually wide regions of vortex liquid states [2,3].For URu 2 Si 2 , the capability of growing ultra-clean crystals clearly contributed to the observation of liquid state [2].The situation is more complex for UCoGe, since the compound exhibits spin-triplet SC and the vortex liquid state is accompanied by a fieldreinforcement of superconductivity for the field applied along a magnetically hard-axis [3].There, the weakening of the pinning force due to the formation of nonsingular fractional vortices has been discussed [3].Such fractional vortices may host Majorana fermions, which obey non-Abelian statistics [4,5].These studies stimulate our interest in investigating the vortex dynamics in the spintriplet superconductor UTe 2 [6][7][8][9][10][11][12][13][14][15][16][17], which was recently shown to have multiple SC states under magnetic fields along the magnetic hard b-axis [9,10,12,14,18].
For UTe 2 , significant efforts have been made to improve crystal quality [19][20][21].The recent progress of growing clean crystals has led to the observation of quantum oscillations [21][22][23][24][25] and renewed the SC phase diagram with higher B c2 [18,26].The reinforcement of superconductivity occurs for the field along the b-axis, where the applied field initially suppresses superconductivity, but enhances T c above B ⋆ ∼15 T, causing a minimum of T c (B) at B ⋆ [6,8,12].The recent studies have revealed the presence of a phase boundary within the SC state for B b, which divides the superconductivity into low and high-field SC states [10,12].Most recently, another phase boundary has been found in the low-field SC state around B ⋆ , implying the presence of in-total three SC states with the intermediate SC (IFSC) state, which may be characterized by mixture of multiple SC order parameters from the low-and high-field SC states (LFSC and HFSC states) [18,27].
In this Letter, using an ultra-clean single crystal grown by the molten-salt flux method [21], we study the vortex dynamics in the multiple SC states of UTe 2 .Remarkably, our direct current (DC)-electrical resistivity measurements with different currents reveal a sudden weakening of the pinning force in the IFSC state for B b [18].This may be caused by the formation of nonsingular vortices in the IFSC state, where the SC order parameter does not vanish entirely in vortex cores due to the mixing of multiple SC components.DC-resistivity measurements were performed using the four-probe method and a 3 He cryostat with an SC magnet in the High-Field Laboratory for Superconducting Materials at the Institute for Materials Research at Tohoku University.The sample was placed inside 3 He liquid during the measurements.The rod-shaped sample used for the measurements has a cross-sectional area of 0.29×0.26=0.075mm 2 and a length of 2.2 mm along the a-axis between the voltage contacts.Magnetic field was applied along the b-axis.The sample, grown by moltensalt flux method, has a SC transition temperature of T c =2.1 K [21].The Joule heating effect was examined by applying current in the normal conducting state at a temperature of 1.46 K and in magnetic field of 20 T. The voltage shows no deviation from the linear dependence of the electrical current (I) within the experimental accuracy up to 60 mA.Above this current, it deviates with an upward curvature due to heating.We can neglect the Joule heating effect because the upper bound of the ohmic region, 60 mA, is 10 times larger than the typical current, 6 mA and larger than the maximum current of 45 mA for measurements of E − J characteristics.
Figures 1(a,b) show the DC-resistivity with two different currents, 2 and 6 mA along the a-axis under magnetic fields of 12 and 16 T along the b-axis.While the SC transition is sharp at B=12 T, it broadens significantly at 16 T.The data with 6 mA at 16 T shows zero resistance below 1 K and remarkably recovers nonzero resistance below 0.8 K.The difference between ρ measured by the two different currents, ρ 6mA − ρ 2mA , is plotted in Fig. 1(c).A peak at the normal conducting (NC)-SC transition temperature, T c , is clearly broader for B=16 T than for B=12 T. The full width at half maximum of the peak at T c is plotted in Fig. 1(d).The position of stepwise increase, B=15 T, coincides with the multi-critical point of different SC states, B ⋆ [10,12,18].This result is consistent with the reported broadening of the transition for the high-field reinforced SC state [12,18].
From resistivity measurements at various magnetic fields, we constructed the color contour plot of ρ 6mA − ρ 2mA as shown in Fig. 2. It reproduces the peculiar NC-SC phase boundary with the reinforcement of superconductivity above B ⋆ ∼15 T. Our T c (B) agrees well with the reported one for low fields below B ⋆ , whereas it is slightly shifted to lower temperatures by ∼0.2 K at high fields above B ⋆ .The shift only for HFSC state is explained by a sample miss-alignment of ∼2 degree from B b-axis, because T c for the HFSC state is very sensitive to the field angle, whereas that for the LFSC state The plot is constructed from the temperature-dependent DCresistivity ρ(T ) measurements at various magnetic fields.ρ(T ) at 2 and 6 mA are taken at magnetic fields from 0 to 12 T with an interval of ∆B=2 T, from 13 to 22 T with ∆B=1 T and taken finally at 24 T. The solid blue lines are the phase boundaries determined by the recent study [21]."LFSC", "IFSC" and "HFSC" denote the low-field, intermediate-field and high-field superconducting states, respectively [21].
is much less sensitive [18].
The peculiar behavior of ρ(T ) with 6 mA at B=16 T indicates that the vortices form a solid below T c and start to flow below 0.8 K.For 2 mA vortices remain solid down to 0.45 K.The vortex-flow state for 6 mA corresponds to the finite ρ 6mA − ρ 2mA region deep inside the SC state, which spans magnetic fields of 14-21 T and temperatures below 0.8 K. Here, it should be mentioned that the color coding in Fig. 2 does not represent the vortex-flow resistivity, ρ f =dE/dj, where E and j are the electric field and current density, respectively.It rather highlights the region of low critical current because the light color indicates the region of critical current lower than 6 mA.More detailed investigations on the vortex-flow resistivity are left for future studies.As shown in Fig 1(c), ρ 6mA −ρ 2mA at 16 T exhibits the two vortex-flow states right below T c and below 0.8 K, separated by a solid state around 0.9 K.Such a separation is always observed in any magnetic fields of our ρ(T ) measurements between 12 and 22 T, with an interval of 1 T. Because thermal fluctuations increase with temperature, fluctuation-induced vortexflow would not disappear with increasing temperature but rather persists up to T c .Therefore, the formation of island region of low critical current deep inside the SC state is ascribed to weakening of vortex pinning.Reflecting the separation, the critical current density j c , needed to induce finite resistivity, exhibits an unusual maximum as a function of temperature and decreases on entering the IFSC state (the inset of Fig. 3).Notably, there is a narrow field range around 18 T of ρ 6mA − ρ 2mA = 0 in the middle of the low j c region.This separates the low j c region into lower and higher field ones, spanning 14-17 and 19-21 T, respectively.This is not an experimental error but rather reproducible.The magnetic field dependence of ρ 6mA clearly indicates vortex solidification with ρ 6mA =0 at 18 T between the two flow states with nonzero ρ 6mA (Fig. 3).There is no clear hysteresis between the data for sweeping magnetic field up and down.The field range of solidification is independent of temperature.Therefore, it might be caused by a kind of matching effect of vortices.
Figures 4(c,d) show the E − j characteristics in the two regions of the low j c .They indicate a narrow E = 0 region of the vortex solid state for |j| < 4×10 4 A/m 2 (3 mA).On the other hand, at an elevated temperature of 0.75 K for B=20 T, the critical current density 27×10 4 A/m 2 to induce non-zero E is much larger.Interestingly, both data sets at 17 and 20 T display unusual currentdensity dependence.At 20 T, E increases with j at low j region, but turns to decrease above j=2×10 5 A/m 2 and almost reaches E = 0 (solidification).Furthermore, we note that E shows repeated sharp changes between the low and high values in the j range.This indicates that less-movable vortices suddenly flow at random j values, released from vortex pinning.This behavior is reproducible in the reversed current direction (j < 0) and occurs only for sweeping up the magnitude of the current FIG. 4. Electric field-current (E − J) characteristics deep inside SC state at B=20 and 17 T. Dotted lines represent the resistivity of NC state, which is determined by extrapolating NC resistivity with T 2 -dependence to the measurement temperatures for E − J characteristics.Data at T =0.75 K for B=20 T is plotted for comparison (red).The maximum current density corresponds to a current of 45 mA.density |j|, resulting in the hysteresis.At 17 T, the same but much weakened behavior is observed at a slightly elevated |j| range.Additionally, the slope becomes smaller in the same |j| range.The origin of the stronger pinning force in this |j| range calls for future studies.
We discuss the possible origins of the weakening of the pinning force deep inside the SC state.The vortexflow region shown in Fig. 2 coincides well with the recently proposed IFSC state, which has a lower-field phase boundary around 14 T [18].Therefore, the weaker pinning force arises from the properties of the IFSC state [18,27].
With the orthorhombic crystal structure of UTe 2 , the SC states are classified into A For the SC gap structure, the former has symmetry protected point nodes on the k y axes, whereas the latter has a line node on the k y = 0 plane.Although it has not been settled which of the two representations corresponds to the LFSC or the HFSC states, the change in the SC gap structure would result in a change in the pinning force by modifying the interaction between vortices and impurities/defects.The anisotropy of the SC gap influences both the vortex core and lattice structure, as the latter discussed for the multiple SC states of UPt 3 [28,29].
Furthermore, if the IFSC state could be characterized by a mixing of the multiple SC components from the LFSC and HFSC states, i.e.A b u + B b u , as a consequence that, the formation of nonsingular, coreless vortices may be expected [5,[30][31][32][33][34].Such coreless (fractional) vortices, have been theoretically discussed, for example, in a field-induced chiral state of Sr 2 RuO 2 [35], where the corresponding chiral state is characterized by degenerate pairing states with multiple (=4) components, and the fractional vortex lattice is suggested to be stabilized by the spin-orbit coupling.In general, vortices are pinned at impurities/defects, because the energy cost is minimized when the NC vortex cores are positioned at the impurities/defects, where the superconductivity is weaker or absent.In a nonsingular vortex state with multiple SC components, different components form vortex lattices separately, with the real-space positions of vortex cores shifted relative to each other [35,36].This results in the non-zero SC order parameter everywhere, reducing the pinning force.In this case, several possibilities would explain the observed pinning around B = 18T.One possibility is a matching between the lattice constants of the two vortex lattices, which may have different field dependencies.Another possibility is a first-order vortexlattice phase transition, unique in such a mixed SC state.At magnetic fields just above (below) the LFSC-IFSC (IFSC-HFSC) transition field, the vortex lattice structure in the IFSC state would be mainly determined by the dominating LFSC (HFSC) order parameter.Then, there may be a phase transition between the two competing vortex structures at magnetic fields in the middle of the IFSC state.If this transition is of first order, there would be domains and domain walls, causing additional vortex pinning.It should be noted however that the formation of a nonsingular vortex state in bulk superconductors is still under debate.It has been argued that such a vortex state would be energetically unstable [33,37].Since there are only few examples of superconductors with multiple SC states, further studies are needed to understand the vortex dynamics across different SC states in spin-triplet superconductors.
In conclusion, we studied the vortex dynamics in UTe 2 by measuring DC-electrical resistivity with different currents along the a-axis under magnetic fields along the b-axis.We found a region of low critical current deep inside the SC state, which agrees with the recently proposed IFSC state [18].The island formation of the low critical current region leads to an unusual maximum of critical current as a function of temperature.The accompanying decrease in the critical current with decreasing temperature cannot be explained by thermal fluctuations but is ascribed to the weakening of the pinning force.We discuss the possible origins for the weakening of the pinning force, including changes in the SC gap structure and nonsingular vortex states, which may host Majorana fermions [4,5].Further intensive studies are required to understand the anomalous vortex state in spin-triplet superconductors.
FIG. 1 .
1
FIG. 1. DC-resistivity of UTe2 measured with different currents, 2 mA (grey, pink) and 6 mA (black, red) along a-axis under magnetic fields of 12 T (a) and 16 T (b) along b-axis.(c) The difference between the resistivity with the two currents, ρ6mA − ρ2mA, at B=12 and 16 T.(d) Magnetic field dependence of the full width of half maximum for the peak observed in ρ6mA − ρ2mA at the normal conducting-superconducting transition temperature.
FIG. 2 .
2
FIG.2.Color contour plot of the difference ρ6mA − ρ2mA.The plot is constructed from the temperature-dependent DCresistivity ρ(T ) measurements at various magnetic fields.ρ(T ) at 2 and 6 mA are taken at magnetic fields from 0 to 12 T with an interval of ∆B=2 T, from 13 to 22 T with ∆B=1 T and taken finally at 24 T. The solid blue lines are the phase boundaries determined by the recent study[21]."LFSC", "IFSC" and "HFSC" denote the low-field, intermediate-field and high-field superconducting states, respectively[21].
FIG. 3 .
3
FIG.3.Magnetic field dependence of the resistivity of UTe2 at a temperature of 0.5 K for the field along the b-axis with a current of 6 mA along the a-axis.The black and red curves are the data taken by sweeping magnetic field up and down, respectively.The red, yellow and green colored regions indicated by "LFSC", "IFSC" and "HFSC" are the low-field, intermediate-field and high-field superconducting states, respectively.Inset shows the critical current density, jc, at B=20 T which is needed to induce finite resistivity."Tc" denotes the normal conducting (NC)-superconducting phase transition determined by zero resistance with a small current of 0.5 mA.
resentations when the magnetic field is applied along the b axis[27].Using the classification of the odd-parity SC order parameters for the point group D 2h at zero field, the A b u and B b u states are represented as A b u = A u +B 2u and B b u = B 1u +B 3u , respectively.
We thank J. Goryo, Y. Matsuda, M. Garst, T. Takimoto, Y. Nagai and M. Machida for stimulating discussions.We thank M. Nagai and K. Shirasaki for experimental support.The work was supported by JSPS KAKENHI Grant Numbers, JP20K20905, 20KK0061, JP21H05470, JP22H01176, JP22H00109.This work (A part of high magnetic field experiments) was performed at HFLSM under the IMR-GIMRT program (Proposal Numbers 202012-HMKPB-0012, 202112-HMKPB-0010, 202112-RDKGE-0036 and 202012-RDKGE-0084).
Vortices in high-temperature superconductors. G Blatter, M V Feigel'man, V B Geshkenbein, A I Larkin, V M Vinokur, 10.1103/RevModPhys.66.1125Rev. Mod. Phys. 6611251994
Flux line lattice melting and the formation of a coherent quasiparticle bloch state in the ultraclean URu2Si2 superconductor. R Okazaki, Y Kasahara, H Shishido, M Konczykowski, K Behnia, Y Haga, T D Matsuda, Y Onuki, T Shibauchi, Y Matsuda, 10.1103/PhysRevLett.100.037004Phys. Rev. Lett. 100370042008
Vortex liquid phase in the p-wave ferromagnetic superconductor UCoGe. B Wu, D Aoki, J.-P Brison, 10.1103/PhysRevB.98.024517Phys. Rev. B. 98245172018
Paired states of fermions in two dimensions with breaking of parity and time-reversal symmetries and the fractional quantum hall effect. N Read, D Green, 10.1103/PhysRevB.61.10267Phys. Rev. B. 61102672000
Non-abelian statistics of halfquantum vortices in p-wave superconductors. D A Ivanov, 10.1103/PhysRevLett.86.268Phys. Rev. Lett. 862682001
Nearly ferromagnetic spin-triplet superconductivity. S Ran, C Eckberg, Q.-P Ding, Y Furukawa, T Metz, S R Saha, I.-L Liu, M Zic, H Kim, J Paglione, N P Butch, 10.1126/science.aav8645Science. 3656842019
Unconventional superconductivity in heavy fermion UTe2. D Aoki, A Nakamura, F Honda, D Li, Y Homma, Y Shimizu, Y J Sato, G Knebel, J.-P Brison, A Pourret, D Braithwaite, G Lapertot, Q Niu, M Vališka, H Harima, J Flouquet, 10.7566/"J.Phys.Soc.Jpn.".88.043702Journal of the Physical Society of Japan. 88437022019
Field-reentrant superconductivity close to a metamagnetic transition in the heavy-fermion superconductor UTe2. G Knebel, W Knafo, A Pourret, Q Niu, M Vališka, D Braithwaite, G Lapertot, M Nardone, A Zitouni, S Mishra, I Sheikin, G Seyfarth, J.-P Brison, D Aoki, J Flouquet, 10.7566/"J.Phys.Soc.Jpn.".88.063707Journal of the Physical Society of Japan. 88637072019
Multiple superconducting phases and unusual enhancement of the upper critical field in UTe2. D Aoki, F Honda, G Knebel, D Braithwaite, A Nakamura, D Li, Y Homma, Y Shimizu, Y J Sato, J.-P Brison, J Flouquet, 10.7566/"J.Phys.Soc.Jpn.".89.053705Journal of the Physical Society of Japan. 89537052020Journal of the Physical Society of Japan
Change of superconducting character in UTe2 induced by magnetic field. K Kinjo, H Fujibayashi, S Kitagawa, K Ishida, Y Tokunaga, H Sakai, S Kambe, A Nakamura, Y Shimizu, Y Homma, D X Li, F Honda, D Aoki, K Hiraki, M Kimata, T Sasaki, 10.1103/PhysRevB.107.L060502Phys. Rev. B. 107L0605022023
Unconventional superconductivity in UTe2. D Aoki, J.-P Brison, J Flouquet, K Ishida, G Knebel, Y Tokunaga, Y Yanase, 10.1088/1361-648X/ac5863Journal of Physics: Condensed Matter. 342430022022
Field-induced tuning of the pairing state in a superconductor. A Rosuel, C Marcenat, G Knebel, T Klein, A Pourret, N Marquardt, Q Niu, S Rousseau, A Demuer, G Seyfarth, G Lapertot, D Aoki, D Braithwaite, J Flouquet, J P Brison, 10.1103/PhysRevX.13.011022Phys. Rev. X. 13110222023
Superconducting order parameter in UTe2 determined by knight shift measurement. H Fujibayashi, G Nakamine, K Kinjo, S Kitagawa, K Ishida, Y Tokunaga, H Sakai, S Kambe, A Nakamura, Y Shimizu, Y Homma, D Li, F Honda, D Aoki, 10.7566/"J.Phys.Soc.Jpn.".91.04370591.043705Journal of the Physical Society of Japan. 91437052022J. Phys. Soc. Jpn
Multiple superconducting phases in a nearly ferromagnetic system. D Braithwaite, M Vališka, G Knebel, G Lapertot, J P Brison, A Pourret, M E Zhitomirsky, J Flouquet, F Honda, D Aoki, 10.1038/s42005-019-0248-zCommunications Physics. 21472019
Tuning magnetic confinement of spin-triplet superconductivity. W.-C Lin, D J Campbell, S Ran, I.-L Liu, H Kim, A H Nevidomskyy, D Graf, N P Butch, J Paglione, 10.1038/s41535-020-00270-wnpj Quantum Materials. 5682020
Chiral superconductivity in heavy-fermion metal UTe2. L Jiao, S Howard, S Ran, Z Wang, J O Rodriguez, M Sigrist, Z Wang, N P Butch, V Madhavan, 10.1038/s41586-020-2122-2Nature. 5795232020
Orientation of point nodes and nonunitary triplet pairing tuned by the easy-axis magnetization in UTe2. S Kittaka, Y Shimizu, T Sakakibara, A Nakamura, D Li, Y Homma, F Honda, D Aoki, K Machida, 10.1103/PhysRevResearch.2.032014Phys. Rev. Research. 2320142020
H Sakai, Y Tokiwa, P Opletal, M Kimata, S Awaji, T Sasaki, D Aoki, S Kambe, Y Tokunaga, Y Haga, 10.48550/ARXIV.2210.05909Field induced multiple superconducting phases in UTe2 along hard magnetic axis. 2022
Effect of uranium deficiency on normal and superconducting properties in unconventional superconductor UTe2. Y Haga, P Opletal, Y Tokiwa, E Yamamoto, Y Tokunaga, S Kambe, H Sakai, 10.1088/1361-648X/ac5201Journal of Physics: Condensed Matter. 341756012022
Single thermodynamic transition at 2 K in superconducting UTe2 single crystals. P F S Rosa, A Weiland, S S Fender, B L Scott, F Ronning, J D Thompson, E D Bauer, S M Thomas, 10.1038/s43246-022-00254-2Communications Materials. 3332022
Single crystal growth of superconducting UTe2 by molten salt flux method. H Sakai, P Opletal, Y Tokiwa, E Yamamoto, Y Tokunaga, S Kambe, Y Haga, 10.1103/PhysRevMaterials.6.073401Phys. Rev. Materials. 6734012022
First observation of the de haas-van alphen effect and fermi surfaces in the unconventional superconductor UTe2. D Aoki, H Sakai, P Opletal, Y Tokiwa, J Ishizuka, Y Yanase, H Harima, A Nakamura, D Li, Y Homma, Y Shimizu, G Knebel, J Flouquet, Y Haga, 10.7566/JPSJ.91.083704Journal of the Physical Society of Japan. 91837042022
A G Eaton, T I Weinberger, N J M Popiel, Z Wu, A J Hickey, A Cabala, J Pospisil, J Prokleska, T Haidamak, G Bastien, P Opletal, H Sakai, Y Haga, R Nowell, S M Benjamin, V Sechovsky, G G Lonzarich, F M Grosche, M Valiska, arXiv:2302.04758Quasi-2d fermi surface in the anomalous superconductor UTe2. 2023cond-mat.supr-con
Revealing a 3d fermi surface and electron-hole tunneling in UTe2 with quantum oscillations. C Broyles, Z Rehfuss, H Siddiquee, K Zheng, Y Le, M Nikolo, D Graf, J Singleton, S Ran, arXiv:2303.090502023cond-mat.str-el
de haas-van alphen oscillations for the field along c-axis in UTe2. D Aoki, I Sheikin, A Mccollam, J Ishizuka, Y Yanase, G Lapertot, J Flouquet, G Knebel, 10.7566/JPSJ.92.065002Journal of the Physical Society of Japan. 92650022023
Y Tokiwa, P Opletal, H Sakai, K Kubo, E Yamamoto, S Kambe, M Kimata, S Awaji, T Sasaki, D Aoki, Y Tokunaga, Y Haga, arXiv:2210.11769Stabilization of superconductivity by metamagnetism in an easy-axis magnetic field on UTe2 (2022). cond-mat.supr-con
Insulator-metal transition and topological superconductivity in UTe2 from a first-principles calculation. J Ishizuka, S Sumita, A Daido, Y Yanase, 10.1103/PhysRevLett.123.217001Phys. Rev. Lett. 1232170012019
Field dependence of the vortex structure in d-wave and s-wave superconductors. M Ichioka, A Hasegawa, K Machida, 10.1103/PhysRevB.59.8902Phys. Rev. B. 5989021999
Realignment of the flux-line lattice by a change in the symmetry of superconductivity in UPt3. A Huxley, P Rodière, D M Paul, N Van Dijk, R Cubitt, J Flouquet, 10.1038/35018020Nature. 4061602000
Circulation and angular momentum in the a phase of superfluid Helium-3. N D Mermin, T.-L Ho, 10.1103/PhysRevLett.36.594Phys. Rev. Lett. 365941976
Phase slippage without vortex cores: Vortex textures in superfluid 3 He. P W Anderson, G Toulouse, 10.1103/PhysRevLett.38.508Phys. Rev. Lett. 385081977
Quantized vortices in superfluid 3 He. M M Salomaa, G E Volovik, 10.1103/RevModPhys.59.533Rev. Mod. Phys. 595331987
Phenomenological theory of unconventional superconductivity. M Sigrist, K Ueda, 10.1103/RevModPhys.63.239Rev. Mod. Phys. 632391991
Observation of half-quantum vortices in topological superfluid 3 He. S Autti, V V Dmitriev, J T Mäkinen, A A Soldatov, G E Volovik, A N Yudin, V V Zavjalov, V B Eltsov, 10.1103/PhysRevLett.117.255301Phys. Rev. Lett. 1172553012016
Spin-triplet pairing state of Sr2RuO4 in the c-axis magnetic field. S Takamatsu, Y Yanase, 10.7566/JPSJ.82.063706Journal of the Physical Society of Japan. 82637062013
Fractional vortex lattice structures in spin-triplet superconductors. S B Chung, D F Agterberg, E.-A Kim, 10.1088/1367-2630/11/8/085004New Journal of Physics. 11850042009
Vortices with fractional flux in twogap superconductors and in extended faddeev model. E Babaev, 10.1103/PhysRevLett.89.067001Phys. Rev. Lett. 89670012002
| [
-0.179303377866745,
-0.1178240180015564,
-0.07325670123100281,
-0.04377042502164841,
0.06738026440143585,
0.09410737454891205,
-0.056259311735630035,
-0.016549183055758476,
0.05598217248916626,
0.005905007012188435,
0.006304558832198381,
-0.016476385295391083,
0.012649200856685638,
-0.1207... |
Analysis of Speech Separation Performance Degradation on Emotional Speech Mixtures
Jia Qi
Speech Lab of DAMO Academy
Alibaba Group
Nanyang Technological University
Singapore
Dianwen Ng
Speech Lab of DAMO Academy
Alibaba Group
Nanyang Technological University
Singapore
Bin Ma
Speech Lab of DAMO Academy
Alibaba Group
Chng Eng
Nanyang Technological University
Singapore
Analysis of Speech Separation Performance Degradation on Emotional Speech Mixtures
97A794A116226FAEB165D3B1AD9FC266speech separationtransformerdeep learningemotional speechemotion classification
Despite recent strides made in Speech Separation, most models are trained on datasets with neutral emotions.Emotional speech has been known to degrade performance of models in a variety of speech tasks, which reduces the effectiveness of these models when deployed in real-world scenarios.In this paper we perform analysis to differentiate the performance degradation arising from the emotions in speech from the impact of out-ofdomain inference.This is measured using a carefully designed test dataset, Emo2Mix, consisting of balanced data across all emotional combinations.We show that even models with strong out-of-domain performance such as Sepformer can still suffer significant degradation of up to 5.1 dB SI-SDRi on mixtures with strong emotions.This demonstrates the importance of accounting for emotions in real-world speech separation applications.
I. INTRODUCTION
Speech Separation is the task of obtaining single speaker speech from a mixture of speakers, also known as the cocktail party problem [1].It has been the focus of much recent research, as many downstream speech models for tasks such as Automatic Speech Recognition (ASR) [2] are trained on single talker speech.For deployment, mixed speech received from the wild should ideally be separated before performing ASR.
The effect of a speaker's emotions on their speech [3] and speaker emotion recognition [4] are well studied research areas.The emotions of a speaker or the intention of a speaker to convey emotion can result in differences in speech.While some of the differences are semantic [5], there are clear differences also manifest in the prosody [6] and articulation [7] of words.Thus, emotional differences in speech can show up at the frame level, where speech separation models operate.
The difference in sound between neutral or read speech and emotional speech has been shown to lead to performance degradation on a number of speech tasks such as speaker verification [8] and ASR [9].Conversely, a mixture of speakers with different emotions also results in a degradation of emotion recognition performance [10].
The separation of emotional speech is important because overlapping speech often occurs when speakers are at heightened emotional states, such as in a heated argument or excited conversation, where the typical decorum of turn taking is breached [11].Speech Separation models are often trained on datasets built from neutral speech.The most common datasets used for speech separation are LibriMix [12] created from the LibriSpeech [13] corpus and WSJ0Mix [14] created from the WSJ0 [15] corpus.Both datasets consist of read speech recorded under controlled conditions and neither are explicitly emotional datasets.This results in a potential mismatch between speech separation models trained primarily on neutral speech and the real-world emotional speech mixtures.
A. Our Approach
In this paper analyses the performance degradation of speech separation models using a custom speech separation test dataset, Emo2Mix, built based utterances from the Ryerson Audio-Visual Database of Emotional Speech and Song (RAVDESS) [16].To the authors' knowledge this is the first study to properly investigate the impact of emotions on speech separation with a test dataset that is balanced across multiple emotions at two different emotional intensities.
Using this dataset, we conduct a detailed analysis of the impact of emotional speech on state-of-the-art speech separation models that were trained on neutral speech.To control for the out-of-domain issue due to the unseen speakers in the Emo2Mix test dataset, we make use of the neural emotion utterances present within the RAVDESS dataset as a baseline for an out-of-domain speaker with an "in-domain" emotion.
We show that Emo2Mix presents a significant challenge to speech separation models trained on neutral speech with a arXiv:2309.07458v1[cs.SD] 14 Sep 2023 recent state-of-the-art Sepformer model [17][18] experiencing a performance degradation of 7.0dB compared to its Libri2Mix baseline.Of this, a performance difference of 1.9dB can be attributed to emotions alone, when comparing against the indomain neutral emotion baseline.
B. Related Work
Recently, [19] also proposed an emotional mixture test dataset based on the RAVDESS [16] dataset, RAVDESS2Mix.The dataset consists of mixtures from the RAVDESS dataset and LibriSpeech [13] dataset, as well as enrollment speech from the RAVDESS dataset for the target speaker extraction task.
Compared to RAVDESS2Mix [19], our proposed Emo2Mix dataset does not consist of any utterances from the LibriSpeech corpus.This is for two reasons.Firstly, the LibriSpeech corpus consists exclusively of neutral speech, which limits the number of emotion combinations possible for the dataset.Secondly, many speech separation models are trained on the Libri2Mix dataset, which uses utterances from the LibriSpeech corpus.This makes the RAVDESS2Mix test dataset biased, as models pretrained on Libri2Mix will have and advantage over models pretrained on other datasets such as the commonly used WSJ02Mix dataset, which creates utterances from the WSJ0 corpus.Based on the RAVDESS2Mix [19] proposed that target speaker extraction is negatively impacted by emotional speech while blind source separation was not as significantly impacted.However, using Emo2Mix, we can show that the same performance degradation is observed once the in-domain advantage of Librispeech models are removed.
II. METHODOLOGY A. Evaluation
The performance of the models are measured using Scaleinvariant signal-to-distortion ratio improvement (SI-SDRi) which is measured by comparing the output waveforms of the models with the ground-truth waveforms.Since there are multiple outputs, the final performance is calculated using the permutation invariant approach.
B. The RAVDESS dataset
The RAVDESS dataset [16] is an emotional dataset consisting of 7356 recordings by 24 actors, gender balanced with 12 male and 12 female.The actors vocalize two lexicallymatched statements in a neutral North American accent at two emotional intensities, normal and strong.At the normal emotional intensity, 8 emotions are expressed (neutral, calm, happy, sad, angry, fearful, disgust, surprised) while the strong intensity share the same emotions except for neutral.
RAVDESS has a number of advantages over other emotional speech databases because of its inclusion of two neutral emotions, "neutral" and "calm" and two emotional intensities "normal" and "strong".These features are useful for comparison with existing corpora like LibriMix and WSJ0Mix which also call in this emotional category.These baselines can help differentiate between the performance impact of out-of-domain inference from the unseen speakers and the actual performance impact of the emotional speech.
C. Emo2Mix
The Emo2Mix dataset draws from the RAVDESS dataset to produce two-speaker mixtures of emotional speech.The subset of RAVDESS selected for Emo2Mix excludes singing speech.It also excludes the audiovisual data.A breakdown of the features in the chosen subset of the RAVDESS dataset is shown in Table I.The mixtures are created with an even distribution across 64 combinations of 8 emotions at a normal emotional intensity and 49 combinations of 7 emotions at a strong emotion intensity.Each statement in the mixture is different, so the mixtures are produced as permutations and not combinations of emotions.While each actor will vocalize the same statement at the same emotion twice, to reduce superfluous mixtures we simply randomly select one of the two repetitions.
For each of the 113 emotion-intensity combinations, each actor vocalizes 2 different statements, from which we can create N × (N − 1) combinations can be obtained, since we cannot mix a actor with themselves.For the full dataset, N = 24, which results in 552 mixtures per emotion-intensity permutation which would result in 552 × 113 = 62, 376 mixtures overall.To reduce the number of testing mixtures, we reduce the number of speakers in the test set by setting N = 8, which results in 56 mixtures per emotion-intensity permutation.This gives 56 × 64 = 3, 584 mixtures for the normal intensity test set, and 56 × 49 = 2, 744 mixtures for the strong intensity test set.This is done by selecting only every third speaker (1,4,7,10,13,17,21,24) from the dataset.This approach, as opposed to randomly selecting 8 out of 24 of the speakers, is chosen so as to enable the possibility of future work on fine-tuning-models on the other 16 held-out speakers.
The utterances selected from the RAVDESS dataset are dynamically mixed [20] so that the mixture test set does not have to be separately stored.During mixing, a number of preprocessing steps are performed in line with the parameters used for dynamic mixing [20] implemented on the Speechbrain [21] framework.Two audio segments are first cropped to the length of the minimum of the two, then downsampled to 8kHz and normalized.These processed segments are then combined at equal weights if no clipping is observed, or reweighted if TABLE II: Overall results across different datasets, with aggregated results reported for the emotional datasets.The performance degradation due to only emotional mixtures is calculated by ( 4)-( 6) which is the difference in performance between the Strong emotion and the Neutral emotion baseline.Out-of-domain performance degradation, independent of emotions can be measured by the difference between the original baseline and the Emo2Mix (Neutral) mixtures, calculated by ( 1 clipping is present.To ensure the reputability of the results we used fixed random seeds for all dataset generation and provide a standard script for generation which we release on GitHub 1 .
D. Training Datasets
In this work we focus on models that have been trained on the Libri2Mix [12] and WSJ0-2Mix [14] datasets.The Libri2Mix training set consists of 50,800 mixtures while WSJ0-2Mix training set consists of 20,000 mixtures.Both have test sets of 3,000 mixtures.We note that 3,000 mixtures are comparable to the 3,584 and 2,744 mixtures in the Emo2Mix test set.
E. Baseline Models
We make use to two baseline models, Sepformer which adopts a dual-path speech separation architecture with transformer blocks, and ConvTasNet [22] which utilizes temporal convolution blocks.Both models are seminal in the field of speech separation, with Sepformer [17] [18] being the more recent state-of-the art model.We implement the two models on the Speechbrain framework as per their respective papers.For Sepformer we make use of pre-trained checkpoints available from the speechbrain huggingface 2 .Two versions of the model are available, one trained on Libri2Mix (Sepfromer-L2M) and one trained on WSJ0-2Mix (Sepformer-WJ2).For ConvTasNet we train the model from scratch and validate the model replicating the Libri2Mix-Test baseline.To align with the models available on hugging face, we also train the model on both the Libri2Mix (ConvTasNet-L2M) and WSJ0-2Mix (ConvTasNet-WJ2) datasets.Although newer models surpassing Sepformer have recently been released [23][24], Sepformer and ConvTasNet are currently still more widely used and replicated and thus serve as better baselines.
1 https://github.com/Yip-Jia-Qi/EmoMix 2 https://huggingface.co/speechbrain
III. RESULTS
In Table II we compare the overall separation performance of the baseline models against three different datasets, the original Libri2Mix Test dataset, RAVDESS2Mix and Emo2Mix.For each of the baseline models, we report the results based on pre-training on two different sets of training data, Libri2Mix and WSJ02Mix.The results on the RAVDESS2Mix dataset are provided as a point of comparison between related emotional speech separation test sets.
A. Performance degradation due to emotional speech
The results presented in Table II for Emo2Mix-Normal and Emo2Mix-Strong are aggregated across all emotional combinations through simple averaging, since all emotional combinations are equally weighted.The Emo2Mix (Neutral) test is a subset of the Emo2Mix-Normal test data and consists of 56 mixtures of different speakers where both speakers are portraying neutral emotions.The purpose of Emo2Mix (Neutral) is to serve as a baseline where the speaker is out-ofdomain, but has a neutral emotion matching the emotions in the training data.This allows us to measure the out-of-domain performance degradation, as per (7) in Table II, independent of the impact of emotions.
Any further performance degradation beyond the Emo2Mix (Neutral) baseline, i.e. (8) in Table II, is unlikely to be due to the out-of-domain inference.If emotions do not impact speech separation performance, we should see the values in row (8) approach zero.However, the results of our experiments in Table II show that this is not the case, as the values for (8) range between 1.6dB and 4.0dB.Thus, based on the comparisons of the out-of-domain and emotional degredation in (7) and (8) of Table II, we can conclude that emotions do result in performance degradation in speech separation models.However, the performance impact of performing inference on an unseen speaker is greater than the performance impact from the within-speaker variance resulting from emotions.Taking (8) divided by (7), we see across multiple models that strong emotions can cause an additional 35-55% performance drop on top of the out-of-domain performance drop (7) when compared to the in-domain baseline (1).This shows that although the performance degradation due to emotions ( 8) is less than that from out-of-domain inference (7), the impact is still significant.
We can further support the above conclusion using at the internal consistency in the results of the Emo2Mix test datasets at different emotional intensities.From the results of (4), ( 5) and (6) in Table II we see a significant performance gap between Emo2Mix-Normal and Emo2Mix-Strong, while the gap between Emo2Mix (Neutral) and Emo2Mix-Normal is much smaller.This suggests that emotional speech causes a deterioration in speech separation performance.If emotions do not impact speech separation performance, we should see that Emo2Mix-Normal and Emo2Mix-Strong have the similar performance.Since this is also a within-dataset comparison, the performance difference is not due to differences in speakers, since the speakers in both Emo2Mix-Normal and Emo2Mix-Strong are identical.
B. Comparison with RAVDESS2Mix
The RAVDESS2Mix dataset consists of mixtures of 2 speakers where one speaker is drawn from the RAVDESS dataset while the other speaker is drawn from the Libri2Mix-Test dataset.This means that for a model trained on the Libri2Mix dataset, one of the speakers would be in-domain while the other is out-of-domain.In a 2-speaker separation problem, knowing the mask for one speaker could allow a model to infer the mask for the other speaker.This gives a model trained on the Libri2Mix dataset a big advantage.This is observed across all models, where we see little to no performance degradation for Sepformer-L2M and ConvTasNet-L2M but a significant performance drop for Sepformer-WJ2 and ConvTasNet-WJ2.
Furthermore, when comparing the performance of RAVDESS2Mix-Normal and RAVDESS2Mix-Strong, the latter test set results in a lower performance for models trained on the WSJ0-2Mix dataset but this is not observed for the models trained on the Libri2Mix dataset.This lack of internal consistency across models trained on different training datasets, points to the fact that the use of the Libri2Mix-Test set in the RAVDESS2Mix mixtures allow for the model to bypass having to recognise emotional speech by inferring from the neutral speech from the in-domain Libri2Mix-Test utterance.
In comparison to RAVDESS2Mix, Emo2Mix does not suffer from such an issue and is able to accurately benchmark the impact to performance caused by emotional speech.Across all the models tested, for both Libri2Mix and WSJ0-2Mix trained versions, there is a significant performance difference.This shows that the test dataset we have developed for our analysis, Emo2Mix, is a better benchmark for emotional speech separation than the previously reported RAVDESS2Mix.
C. The benefits of a larger training dataset
It is common to find in various speech domains such as ASR [2] and Keyword spotting [25] [26], that a larger training dataset results in better performance.Since the Libri2Mix training dataset is significantly larger than WSJ0-2Mix we would expect to see a similar trend.Furthermore, Libri2Mix consists of LibriSpeech utterances which come from audio-books which may be closer in domain to the RAVDESS datset.That said, the larger size of the Libri2Mix dataset likely improves the performance of the model on Emo2Mix.Looking only at the Sepformer experiments, we see that on Emo2Mix-Neutral the Sepformer-WJ2 model has a lower SDRi of 12.0 dB compared to 15.5 dB for Sepformer-L2M.The difference in SDRi performance for Emo2Mix-Strong is 1.9 dB on Sepformer-L2M compared to 2.6 dB for Sepformer-WJ2.A similar trend can be found for the ConvTasNet model, with the SDRi dropping to barely above noise at 0.9 dB on Emo2Mix strong.This mirrors the finding of [27] where emotional recognition performance benefited from non-emotional large scale pretraining.
D. Performance Comparisons by emotions
To streamline the performance comparison, we only report here the SI-SDRi metric of the best performing model, Sepformer-L2M.Table III shows the results of the model tested on the Emo2Mix-Normal dataset, while Table IV shows the results of the model tested on the Emo2Mix-Strong dataset.In each of the tables, the highest value in each row is listed in bold and while lowest value is underlined.
In the first column of each table, we also report the comparison with the RAVDESS2Mix dataset (RD2M) to which consists only of a combination of 1 emotional utterance from the RAVDESS dataset and 1 neutral utterance from the Libri2Mix Test dataset.In this comparison we also see that there is a minimal variation in the RD2M dataset across the various emotions of 0.9dB for both the Strong and Normal emotional intensities.Meanwhile the average difference between the min and max emotions across combinations is 2.5dB for the normal intensity and 6.1dB for the strong intensity, with the lowest being 1.5dB for the "sad" emotion row in the normal dataset.Across all combinations in the entire dataset, the difference between the min and max for Emo2Mix-normal is 4.7dB and for Emo2Mix-strong is 9.3dB.
Considering the results on the Emo2Mix-Normal dataset in Table III we see a trend that having an utterance with the surprise emotion consistently results in the worst performance compared to the other emotions, with the worst results arising from a combination of two surprise utterances.One possible explanation is that the actors in the dataset simply found it difficult to express surprise at a low emotional intensity and exhibited the most intense emotions in their surprised utterances compared to the other emotions expressed at normal intensity.Meanwhile sad and angry are emotions expressed at normal intensity could simply be close to neutral, resulting in better SI-SDRi results compared to the other emotions.
Finally, considering the results on the Emo2Mix-Strong dataset in Table IV we see a slightly different dynamic.The Calm utterances consistently have the best results in the Strong dataset compared to the Normal dataset.This could be that Calm utterances are closer to neutral at Strong emotional intensity and thus their contrast with the other strong emotions results makes it easier for the model to differentiate the speakers.
IV. CONCLUSION
In this work we have shown that, contrary to previous work [19], emotions play an important role in the speech separation performance.Our results show that models trained on neutral speech will suffer a performance degradation when the mixture contains strong emotional expressions at inference time.Thus, this work makes the case for the need of including emotional speech into speech separation training datasets.
Fig. 1 .
1
Fig. 1.Illustration of the mixing strategy.Only three emotions are shown here for brevity but the full set of available emotions are used in the dataset (8 at normal intensity and 7 at strong intensity).Each mixture consist of different speakers each vocalizing different statements.The same two statements are shared across emotions and speakers to control for semantic differences.
TABLE I :
I
Breakdown of the features of the selected subset of the RAVDESS dataset used to create Emo2Mix
FeatureNormal StrongNumber of Speakers2424Number of Emotions87Number of Statements22Number of Repetitions22Total Recordings768672
)-(4).
Model:SepformerConvTasNetTraining Dataset:Libri2MixWSJ0-2MixLibri2MixWSJ0-2MixIDTesting DatasetSI-SDRi SDRi SI-SDRi SDRi SI-SDRi SDRi SI-SDRi SDRi1Libri2Mix-Test20.620.917.017.515.115.510.010.62 RAVDESS2Mix-Normal20.220.715.116.015.015.58.69.43RAVDESS2Mix-Strong20.220.714.415.314.915.58.29.14Emo2Mix (Neutral)15.516.312.012.910.511.44.95.85Emo2Mix-Normal15.416.211.412.210.711.43.34.36Emo2Mix-Strong13.614.79.410.38.49.20.92.77(1) -(4)5.14.65.04.64.64.15.14.88(4) -(6)1.91.62.62.62.12.24.03.1
TABLE III :
III
Performance of Sepformer-L2M on the Emo2Mix-Normal dataset broken down by emotion combination reported using SI-SDRi.
RD2Mcalmhappysadangryfearfuldisgustsurprised neutralcalm20.616.015.616.017.115.014.914.615.9happy20.315.714.916.316.315.916.013.516.4sad20.415.615.816.117.116.115.715.716.3angry20.316.514.917.215.016.015.614.416.9fearful20.215.414.316.915.115.915.013.616.4disgust20.015.415.016.315.315.515.113.914.7surprised19.714.412.715.315.214.513.812.514.5neutral19.915.815.816.316.216.815.914.815.5TABLE IV: Performance of Sepformer-L2M on the Emo2Mix-Strong dataset broken down by emotion combination reportedusing SI-SDRi.RD2Mcalmhappysadangryfearfuldisgustsurprisedcalm20.415.917.115.818.617.716.915.9happy20.617.212.413.810.911.214.812.2sad20.115.713.614.715.812.513.113.0angry20.417.611.615.99.310.615.713.6fearful20.318.411.914.111.69.714.911.7disgust19.817.411.714.413.911.813.410.7surprised19.716.712.414.313.011.912.410.4
V. ACKNOWLEDGEMENTSThis research is supported by ST Engineering Mission Software & Services Pte.Ltd under a collaboration programme (Research Collaboration No: REQ0149132).The computational work for this article was partially performed on resources of the National Supercomputing Centre, Singapore (https://www.nscc.sg).
Some experiments on the recognition of speech, with one and with two ears. E C Cherry, The Journal of the acoustical society of America. 2551953
dehubert: Disentangling noise in a self-supervised model for robust speech recognition. D Ng, R Zhang, J Q Yip, Z Yang, J Ni, C Zhang, Y Ma, C Ni, E S Chng, B Ma, 2023
Analyzing emotion in spontaneous speech. R Chakraborty, M Pandharipande, S K Kopparapu, 2018SpringerSingapore
Speech emotion recognition: Emotional models, databases, features, preprocessing methods, supporting modalities, and classifiers. M B Akc, K Oguz, Speech Communication. 1162020
The effect of emotion on voice production and speech acoustics. T Johnstone, Aug 2017
Vocal communication of emotion: A review of research paradigms. K R Scherer, Speech Communication. 4012003
An articulatory study of emotional speech production. S Lee, S Yıldırım, E A Kazemzadeh, S S Narayanan, 2005Interspeech
x-vectors meet emotions: A study on dependencies between emotion and speaker recognition. R Pappagari, T Wang, J Villalba, N Chen, N Dehak, 2020
Emotion impacts speech recognition performance. R Munot, A Nenkova, Proceedings of the 2019 Conference of the North American Chapter of the Association for Computational Linguistics: Student Research Workshop. the 2019 Conference of the North American Chapter of the Association for Computational Linguistics: Student Research WorkshopMinneapolis, MinnesotaAssociation for Computational LinguisticsJun. 2019
Speech separation and emotion recognition for multi-speaker scenarios. R Jin, M Ablimit, A Hamdulla, 2022 3rd International Conference on Pattern Recognition and Machine Learning (PRML). 2022
Towards a conversation-analytic taxonomy of speech overlap. F Gervits, M Scheutz, International Conference on Language Resources and Evaluation. 2018
Librimix: An open-source dataset for generalizable speech separation. J Cosentino, M Pariente, S Cornell, A Deleforge, E Vincent, 2020
Librispeech: An asr corpus based on public domain audio books. V Panayotov, G Chen, D Povey, S Khudanpur, 2015 IEEE International Conference on Acoustics, Speech and Signal Processing. 2015
Deep clustering: Discriminative embeddings for segmentation and separation. J R Hershey, Z Chen, J Le Roux, S Watanabe, 2016 IEEE International Conference on Acoustics, Speech and Signal Processing. 2016
Csr-i (wsj0) complete ldc93s6a. J S Garofolo, D Graff, D Paul, D Pallett, 1993
Funding Information Natural Sciences and Engineering Research Council of Canada: 2012-341583 Hear the world research chair in music and emotional speech from Phonak. S R Livingstone, F A Russo, 10.5281/zenodo.1188976Apr. 2018The Ryerson Audio-Visual Database of Emotional Speech and Song (RAVDESS)
On using transformers for speech-separation. C Subakan, M Ravanelli, S Cornell, F Grondin, M Bronzi, arXiv:2202.028842022arXiv preprint
Attention is all you need in speech separation. C Subakan, M Ravanelli, S Cornell, M Bronzi, J Zhong, ICASSP 2021-2021 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP). IEEE2021
Analysis of impact of emotions on target speech extraction and speech separation. J Švec, K Žmolíková, M Kocour, M Delcroix, T Ochiai, L Mošner, J Černocký, 2022
Wavesplit: End-to-end speech separation by speaker clustering. N Zeghidour, D Grangier, IEEE/ACM Transactions on Audio, Speech, and Language Processing. 292020
Speechbrain: A general-purpose speech toolkit. M Ravanelli, T Parcollet, P Plantinga, A Rouhe, S Cornell, L Lugosch, C Subakan, N Dawalatabad, A Heba, J Zhong, J.-C Chou, S.-L Yeh, S.-W Fu, C.-F Liao, E Rastorgueva, F Grondin, W Aris, H Na, Y Gao, R De Mori, Y Bengio, 2021
Conv-TasNet: Surpassing ideal time-frequency magnitude masking for speech separation. Y Luo, N Mesgarani, IEEE/ACM Transactions on Audio, Speech, and Language Processing. 278aug 2019
Mossformer: Pushing the performance limit of monaural speech separation using gated single-head transformer with convolution-augmented joint self-attentions. S Zhao, B Ma, 2023
TF-GridNet: Integrating full-and sub-band modeling for speech separation. Z.-Q Wang, S Cornell, S Choi, Y Lee, B.-Y Kim, S Watanabe, arXiv:2211.124332022arXiv preprint
Contrastive speech mixup for low-resource keyword spotting. D Ng, R Zhang, J Q Yip, C Zhang, Y Ma, T H Nguyen, C Ni, E S Chng, B Ma, ICASSP 2023 -2023 IEEE International Conference on Acoustics, Speech and Signal Processing. 2023
I2cr: Improving noise robustness on keyword spotting using inter-intra contrastive regularization. D Ng, J Q Yip, T Surana, Z Yang, C Zhang, Y Ma, C Ni, E S Chng, B Ma, 2022 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA ASC). 2022
Pretrained audio neural networks for speech emotion recognition in portuguese. M M Gauy, M Finger, arXiv:2210.147162022arXiv preprint
| [
-0.17937195301055908,
-0.1186663880944252,
0.023532766848802567,
-0.002135464921593666,
0.13751006126403809,
-0.04702846705913544,
0.13223108649253845,
-0.16186992824077606,
0.07180927693843842,
-0.16223208606243134,
-0.03861590474843979,
-0.09283141046762466,
0.01620655693113804,
-0.08810... |
STEREOSELECTIVE SYNTHESIS OF N 1 -6-METHYLURIDINE AND RELATED 2-SUBSTITUTED ANALOGUES
Marco Radi
Dipartimento Farmaco Chimico Tecnologico
Universita' di Siena
via Aldo Moro53100SienaItaly
Elena Petricci
Dipartimento Farmaco Chimico Tecnologico
Universita' di Siena
via Aldo Moro53100SienaItaly
Federico Corelli
Dipartimento Farmaco Chimico Tecnologico
Universita' di Siena
via Aldo Moro53100SienaItaly
Maurizio Botta botta@unisi.it
Dipartimento Farmaco Chimico Tecnologico
Universita' di Siena
via Aldo Moro53100SienaItaly
STEREOSELECTIVE SYNTHESIS OF N 1 -6-METHYLURIDINE AND RELATED 2-SUBSTITUTED ANALOGUES
FF2E2ABD1DFF2A152EEF5973672AC3C0Received, 2nd August, 2006, Accepted, 23rd August, 2006,
Coupling reaction of 2-substituted-6-methyl-4(3H)-pyrimidinones (1a,b) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (ABR) afforded the corresponding N 1 -2,6-disubstituted nucleosides (2a,b) without any trace of the N 3 -isomer.The 2-methylthio-6-methyl derivative (2b) has then proved to be a key intermediate for the synthesis of N 1 -6-methyluridine (4) and the corresponding N 1 -2-amino-6-metyhl derivative (5), suggesting the possibility to obtain different 2,6-disubstituted derivatives by means of methylthio nucleophilic substitution.A
successful solid phase application was also shown.
To date, the main efforts in the discovery of novel antiviral and anticancer nucleosides were generally devoted to the functionalization of the sugar moiety while base modified nucleoside have received so far little attention.In this context, base-modified pyrimidine nucleosides have generally been substituted at C-5 position (i.e.BVDU, CEDU) 1 probably because of the easiness of functionalization at this site (i.e.electrophilic substitution) which could be related to the highest single coefficient in the HOMO of C-5.
While the methods for the preparation of 5-substituted pyrimidine nucleosides are well established, there is a need for yet a easier access to 6-derivatized analogues which, being constrained into a non natural syn-conformation, are of interest as potential antimetabolites.Uridine derivatives bearing a 6-vinyl substituent as well as a 6-fluoromethyl substituent have in fact shown to posses interesting antitumor activity. 2However, according to the results published so far from Vorbrüggen et al., 3 very subtle steric as well as energetic factors seem to drive the formation of N 1 -and N 3 -nucleosides by condensation of 6-substituted nucleobases with the suitable sugar.As a result, a complex mixture of N 1 -and N 3 -isomers, which requires tedious purification, is always obtained.
In order to drive the coupling reaction between 6-substituted pyrimidines and the activated sugar derivative to the exclusive formation of the N 1 -nucleoside, few different strategies have been developed so far: the HETEROCYCLES, Vol.72, 2007 most common method requires a preliminary protection of the amide moiety of the pyrimidine base to give the corresponding N 3 -benzyl derivative, subsequent silylation, condensation with the activated sugar, removal of the benzyl group and final deprotection of the sugar moiety.Otherwise, the formation of the N 3 -nucleoside during the condensation reaction is prevented by transforming the 6-substituted pyrimidines into a 4,6-disubstituted derivatives so that the NH moiety of the nucleobase is no more available for the coupling with the sugar.2b The continued interest of our research group in the synthesis of unnatural nucleosides has prompted us to investigate the synthesis of 6-substituted nucleoside in order to find out a new method for maximal yields or exclusive formation of the N 1 -isomer. 4Since steric factors seem to be of primary importance in the formation of either N 1 -or N 3 -nucleosides in the coupling reaction between silylated 6-methyluridine and the activated sugar, initially we decided to study the effects of a reduced bulkiness around the N 1 atom on the outcome of the coupling reaction.Accordingly, a methoxy group was introduced in the C-2 position of 6-methyluracil.The O-methyl group is chemically very similar to O-trimethylsilyl group of the silylated nucleobase but its smaller size could influence the outcome of the coupling reaction.In order to get the desired N 1 -6-methyluridine (4), compound (2b) was reacted with 3 equivalents of m-chloroperbenzoic acid (m-CPBA) in dichloromethane followed by aqueous workup obtaining compound
(3) in 72% yield (Scheme 2).Final deprotection with methanolic ammonia afforded N 1 -6-methyluridine (4) which chemico-physical properties and NMR data were identical with that of an authentic sample. 6The methylthio group in C-2 played therefore a key role for the stereoselectivity of the coupling reaction and was moreover an interesting site for further functionalization: reacting in fact compound (2b) directly with methanolic ammonia at room temperature for 48 hours, methylthio displacement and sugar deprotection took place at the same time giving the 2-amino-4-methyluridine ( 5) in 68% yield.obtain (7a) in a 54% yield (using 1 eq. of TMSI) while (7b) was obtained in a 30% yield using an excess of TMSI (2 eq.) (Scheme 2).TMSOTf, CH 2 Cl 2 ; iv.ABR, TMSI (1 eq. for 7a and 2 eq for 7b).
As a further extension of our previous work on the solid phase synthesis of pyrimidine nucleosides, 4e the latter modified coupling procedure was also proved to be an interesting approach for the contemporary coupling with the sugar and releasing of the 2,6-disubstituted nucleoside (7b) from the solid support (Scheme 3) since our previously developed Oxone ® cleavage methodology was not effective on solid supported 6-substituted nucleosides.The application of the modified Vorbrüggen's procedure using 3 equivalents of TMSI gave, after 72h, the expected nucleoside (7b) in a good 42% yield.In conclusion, the present work has initially pointed out the interesting role played by the reduced steric hindrance on the C-2 position of 6-methyluracil derivatives on the outcome of the coupling reaction.The stereoselective formation of nucleosides (2a,b) was thus obtained.Subsequent reaction of (2b) with m-CPBA and final deprotection, afforded N 1 -6-methyluridine as single isomer after only three steps starting from (1b).It was moreover observed how, reacting compound (2b) with methanolic ammonia for long time, it was possible to obtain both sugar deprotection and methylthio displacement achieving in this way compound (5).Finally, a modified Vorbrüggen's procedure was successfully applied to the solid-supported nucleobase (8) obtaining the contemporary coupling with the sugar and releasing of the 2,6-disubstituted nucleoside (7b) from the solid support.Both solution and solid phase approaches could therefore be conveniently employed to obtain further 2,6-disubstituted nucleosides in order to study the antimetabolite properties of this new class of compounds.
Scheme 1 .
1
Scheme 1. Reagents and conditions: i. HMDS, (NH 4 ) 2 SO 4 ; ii.ABR, TMSOTf, MeCN
Scheme 2 .
2
Scheme 2. Reagents and conditions: i. m-CPBA (3 eq.), CH 2 Cl 2 , r.t.; ii.MeOH/NH 3 , r.t.; iii.MeOH/NH 3 , r.t.
Scheme 3 .
3
Scheme 3. Reagents and conditions: i. HMDS, (NH 4 ) 2 SO 4 ; ii.ABR, TMSOTf, CH 3 CN; iii.Collidine,
Scheme 4 .
4
Scheme 4. Reagents and conditions: i. Collidine, TMSOTf, CH 2 Cl 2 ; ii.ABR, TMSI (2 eq).
ACKNOWLEDGEMENTSSupport from the European TRIoH Consortium (LSHB-2003-503480) is gratefully acknowledged.
. E De Clercq, J Descamps, P De Somer, P J Barr, A S Jones, R T Walker, H Griengl, M Bodenteich, W Hayden, E Wanek, W Streicher, P Stutz, H Bachmayer, I Ghazzouli, B Rosenwirth, Proc. Natl. Acad. Sci. U.S.A. 16791979, 76, 2947. 1985J. Med. Chem.
. S Megati, R Sodum, G M Otter, R S Klein, B A Otter, Bioorg. Med. Chem. Lett. b) K. Felczak, A. K. Drabikowska, J. A. Vilpo, T. Kulikowski, and D. Shugar17201994, 4, 469. 1996J. Med. Chem.
. U Niedballa, H Vorbrüggen, J. Org. Chem. 36601974
. M Radi, C Mugnaini, E Petricci, F Corelli, M Botta, Tetrahedron Lett. 43612005
. E Petricci, M Radi, F Corelli, M Botta, C Mugnaini, M Botta, M Coletta, F Corelli, F Focher, S Marini, M L Renzulli, A Verri, L Paolini, E Petricci, F Corelli, M Botta, ; E Petricci, M L Renzulli, M Radi, F Corelli, M Botta, R Saladino, C Crestini, A T Palamara, M C Danti, F Manetti, F Corelli, E Garaci, M Botta, Bioorg. Med. Chem. 4445542003. 2003. 2003, 2003, 1039. 2002. 2001J. Med. Chem.
. H Vorbrüggen, K Krolikiewicz, B Bennua, Chem. Ber. 11412341981
. M P Schweizer, J T Witkowski, R K Robins, M W Winkley, R K Robins, J. Am. Chem. Soc. 3328221971, 93, 277. 1968. 2007HETEROCYCLES
| [
-0.05226206034421921,
-0.16561222076416016,
-0.06365391612052917,
-0.1485903561115265,
-0.07505287230014801,
0.060337938368320465,
-0.18924883008003235,
0.03986082226037979,
0.005934665910899639,
0.1451481729745865,
-0.0007234468357637525,
-0.019198983907699585,
-0.05838397145271301,
-0.01... |
KLASIFIKASI MAKANAN TRADISIONAL UNTUK WISATA KULINER DI DESA TEMPOS
Oleh Ni
Luh Kartini niluhkartini21@gmail.com
Lalu Yulendra laluyulendra@gmail.com
Sri Wahyuningsih s.wahyuningsih@yahoo.com
Sekolah Tinggi
Pariwisata Mataram
Kata Kunci
KLASIFIKASI MAKANAN TRADISIONAL UNTUK WISATA KULINER DI DESA TEMPOS
No. 1978-3787278BA0F45BE2F6C9719867A62249477FMakanan TraditionalWisata KulinerTempos
PENDAHULUAN
Faktor pendukung terkenalnya suatu daerah adalah makanan tradisional, dimana makanan biasanya memiliki ciri khas atau spesifisik di daerah tersebut.Makanan tradisional adalah makanan dan minuman, termasuk jajanan serta sera bahan campuran yang digunakan secara tradisional dan telah berkembang di daerah atau masyarakat Indonesia.Biasanya makanan tradisional diolah dari resep yang sudah dikenal masyarakat setempat dengan bahan-bahan yang diperoleh dari sumber lokal yang memiliki citarasa yang relatif sesuai dengan selera masyarakat setempat.Makanan tradisional merupakan makanan yang diperoleh secara turun menurun dan pada setiap daerah mempunyai ciri khas yang berbeda-beda.
Desa Tempos, Gerung -Lombok Barat, belakangan menjadi salah satu destinasi wisata alternatif pilihan di Lombok Barat semenjak terekspos melalui akun media sosial Dinas Pariwisata (Dispar) Kabupaten Lombok Barat pada hari tanggal 8 Agustus 2021 (Sekotong,2021).Memiliki suasana pedesaan yang masih asri dilengkapi dengan pemandangan hamparan sawah yang luas serta pegunungan yang indah oleh karena itu Pokdarwis di Desa Tempos memanfaatkan peluang tersebut sebagai potensi wisata kuliner yang diberi nama kuliner mepet sawah atau biasa dikenal oleh masyarakat umum dengan Makanan tradisional yang dimiliki oleh Desa Tempos merupakan jati diri bagi Desa Tempos itu sendiri.Pelestarian dan pengembangan makanan tradisional adalah suatu upaya yang dilakukan untuk mempertahankan makanan tradisional serta meningkatkan mutu, jumlah dan bentuknya serta membudayakan dikalangan masyarakat supaya lebih dikenal turun temurun.Makanan tradisional memiliki peluang besar untuk ditawarkan seiring meningkatnya jumlah wisatawan yang peduli terhadap budaya dan warisan lokal, makanan tradisional bisa menjadi salah satu cara terbaik untuk mengetahui tentang budaya dan warisan lokal (Sims, 2009).
Inventarisasi merupakan selain sebagai langkah awal mempertahankan budaya bangsa juga untuk mengetahui potensi makanan tradisional di Desa Tempos dalam rangka meningkatkan dan menggalakkan pengembangan wisata kuliner untuk memenuhi kebutuhan wisatawan secara baik dan professional serta sebagai faktor penggerak ekonomi masyarakat khususnya dalam hal bisnis skala kecil.Inventarisasi makanan tradisional merupakan suatu kegiatan pendataan tentang makanan-makanan tradisional meliputi jenis, penggolongan dan dokumentasi yang dijual oleh PPS atau Pedagang Pukul Sembilan sebutan dari para wisatawan yang berkunjung ke Desa Tempos dikarenakan hanya berjualan dari pukul 06.00 sampai pukul 09.00 (Viki,2021).
Berdasarkan pemaparan latar belakang tersebut, maka rumusan masalah dalam penelitian ini antara lain; 1) Apa saja makanan tradisional yang dijual untuk wisata kuliner di Desa Tempos ?, 2) Bagaimana penggolongan makanan tradisional yang dijual untuk wisata kuliner di Desa Tempos ?. Penelitian ini bertujuan untuk menggali dan menentukan golongan makanan tradisional yang dijual untuk menunjang wisata kuliner di Desa Tempos serta memberikan tambahan informasi dan pengetahuan tentang jenis-jenis makanan tradisional yang dijual guna mengembangkan pariwisata di Desa Tempos.
LANDASAN TEORI
Penelitian ini menggunakan beberapa tinjauan pustaka, berikut adalah beberapa konsep utama yang digunakan antaranya ; Selain itu, kegiatan wisata kuliner akan mampu membantu meningkatkan sumber pendapatan pedesaan dan meningkatkan tingkat pendapatan dan pekerjaan tenaga kerja lokal di sekitarnya dan tidak terlepas juga para perempuan.
Sedangkan berdasarkan hasil penelitian Pitanatri (2016) dijelaskan bahwa kuliner lokal terutama kuliner khas Bali telah mampu memberi nuansa baru bagi kepariwisataan khususnya di Ubud.Berkat pengembangan yang dilakukan oleh pengusaha-pengusaha kuliner, sampai saat ini telah mampu menjaga eksistensi kuliner lokal menuju proses keberlanjutan.Hal ini juga telah membantu dalam meningkatkan kesejahteraan masyarakat terutama para pelaku usaha kuliner lokal, meningkatkan eksisitensi dan kualitas sosial budaya serta menjaga keberlanjutan dari aspek lingkungan.
2) Konsep Makanan Tradisonal Menurut Arif Budi (2008) pada prinsipnya makanan Indonesia dapat dikelompokkan sebagai berikut ; a. Hidangan pokok
Makanan pokok adalah makanan utama yang biasa dihidangkan dalam jumlah banyak.Makanan pokok pada masakan Indonesia adalah nasi.Nasi sebagai bahan makanan pokok bagi seluruh lapisan masyarakat Indonesia, menempatkan pertanian padi di posisi utama dalam kebudayaan Indonesia dan membentuk bentang alam yang menghasilkan beras sebagai bahan dasar banyak jenis makanan dari yang gurih hingga manis.Pada umumnya, beras dimakan dalam bentuk nasi biasa yang bercita-rasa tawar dengan sedikit sayurmayur dan lauk-pauk teman nasi disisinya sebagai sumber protein dan sumber gizi lainnya.Beras juga dapat dijadikan ketupat (beras dikukus dalam anyaman daun kelapa), lontong (beras dikukus dalam kemasan daun pisang), intip (kerupuk beras), jajanan, bihun, mi, arak beras, dan nasi goreng, nasi kuning, nasi jagung dan nasi gurih (sega uduk).Pada abad ke-16, bangsa Eropa yang mengunjungi kepulauan Indonesia memandang nasi sebagai makanan bergengsi yang disajikan oleh kaum aristocrat (kelas atas) dan ningrat saat upacara dan perayaan pesta.Bahan makanan pokok lainnya adalah jagung (di kawasan kering seperti Madura dan Nusa Tenggara), sagu (di kawasan Indonesia Timur), singkong (dikeringkan dan disebut tiwul sebagai alternatif makanan pokok di kawasan gersang Jawa seperti Gunung Kidul dan Wonogiri), ketela serta umbi-umbian (khususnya pada musim paceklik atau musim kekurangan bahan makanan).b.Lauk pauk Lauk-pauk adalah suatu hidangan yang merupakan pelengkap nasi yang dapat berasal dari bahan hewani dan produknya, tumbuh-tumbuhan, atau kombinasi bahan hewan dan tumbuhan yang biasanya dimasak dengan bumbu tertentu.Teknik pengolahan lauk pauk diantaranya dengan cara digoreng, dikukus, dibakar, kombinasi dari beberapa teknik atau teknik ganda.
Teknik penyajian lauk pauk dapat dengan per porsi atau secara prasmanan.Bahan makanan sumber protein hewani yang banyak digunakan dalam masakan Indonesia adalah telur, daging, unggas, ikan, hasil laut dan lain-lain.
HASIL DAN PEMBAHASAN Gambaran Umum Desa Tempos
Desa Tempos adalah salah satu desa yang terletak di Kecamatan Gerung, Kabupaten Lombok Barat, Provinsi Nusa Tenggara Barat.Desa Tempos adalah salah satu desa yang memiliki potensi daya tarik wisata karena memiliki hamparan sawah yang luas, pemandangan gunung Sasak dan pemandangan gunung Mereje yang menawarkan pesona tersendiri dan sering disebut mirip seperti Sembalun (Lembah Rinjani).
Desa Tempos menjadi lokasi yang cocok untuk melihat matahari terbit (sunrise) atau matahari terbenam (sunset) sehingga banyak orang yang tertarik untuk datang ke Desa Tempos hanya untuk menikmati atau hanya sekedar datang untuk foto-foto pemandangan yang ada.Masyarakat Desa Tempos terutama para perempuan memanfaatkan kunjungan banyak orang yg menikmati pemandangan dengan berjualan makanan tradisional.
Selain karena didorong oleh kebutuhan hidup, motivasi kaum perempuan untuk bergelut sebagai penjual kuliner adalah karena peluang yang ditawarkan oleh pariwisata.Semakin meningkatnya minat wisatawan terhadap kuliner lokal memberikan peluang besar bagi masyarakat lokal khususnya perempuan untuk menawarkan kekayaan budaya lokal kepada wisatawan dari aspek kulinernya (Suteja & dkk, 2020.).
Klasifikasi jenis makanan tradisional yang ada di Desa Tempos
Berdasarkan hasil survei yang dilakukan, dapat dianalisis bahwa ragam makanan tradisional di Desa Tempos dapat diklasifikasikan menjadi 4 jenis makanan tradisional yang terdiri dari ; 1) Hidangan Pokok, 2) Lauk Pauk, 3) Sayur, 4) Makanan Ringan atau Kudapan.
Untuk lebih jelas mengenai nama makanan berdasarkan pengelompokannya akan diuraikan sebagai berikut ; 1) Hidangan pokok a. Sate Pencok Termasuk ke dalam klasifikasi hidangan pokok karena berbahan dasar beras.Sate Pencok memiliki tekstur yang kenyal dan disajikan dengan siraman kuah bumbu pelalah dan lauk pauk serta pelecing kangkung dikarenakan sebagai sumber karbohidrat.2) Lauk-pauk a. Sate Ampet Umumnya Sate Ampet adalah sate yang terbuat dari daging tetelan atau daging sapi bekas potongan dan usus sapi.Namun, Sate Ampet yang disajikan di Desa Tempos terbuat dari potongan ayam dan usus ayam.
Biasanya dipotong kecil-kecil dan tipis sehingga proses memasaknya menjadi lebih cepat walau hanya dikipaskipas tanpa menggunakan alat modern seperti pengolahan jenis sate lainnya, oleh karena itu disebut dengan Sate Ampet yang dalam bahasa Sasak Ampet mempunyai arti kipas-kipas.
PENUTUP Kesimpulan
Berdasarkan hasil penelitian dan pembahasan yang telah diuraikan di atas, maka dapat disimpulkan bahwa makanan tradisional di Desa Tempos terdapat 15 jenis makanan tradisional yang dapat diklasifikasikan yaitu terdiri dari hidangan pokok berjumlah 3 jenis, lauk pauk berjumlah 3 jenis, sayur berjumlah 3 jenis dan makanan ringan atau kudapan berjumlah 6 jenis.Namun, dari 15 jenis makanan tradisional yang tersedia di Desa Tempos belum ada ciri khas atau makanan asli yang menunjukan identitas dari Desa Tempos itu sendiri dan tidak berpedoman pada suatu resep.
Saran
Para pedagang makanan tradisional di Desa Tempos sebaiknya menambah variasi makanannya agar dapat melengkapi semua klasifikasi makanan tradisional Indonesia untuk mendukung wisata kuliner di Desa Tempos dan setiap hari menggunakan standar resep agar kualitas makanan tersebut tetap terjaga baik dari segi warna, aroma, rasa dan tekstur.
sebutan kuliner mewah.Memiliki daya tarik kuliner lokal yang berpotensi untuk dikembangkan, pokdarwis juga mengharapkan masyarakat di Desa Tempos memanfaatkan makanan tradisional yang dimiliki untuk menunjang potensi wisata kuliner.
Gambar 1 Sate Pencok Sumber : Hasil Penelitian, 2022 Pada umumnya terbuat dari kulit sapi yang sudah dimasak sebelumnya, namun Sate Pencok yang dijual di Desa Tempos berbahan dasar Nasi dan Sagu.Olahan ini masih menjadi makanan tradisional yang biasanya disajikan pada acara-acara tertentu oleh masyarakat di Desa Tempos.b.Nasi Kaput Daun Berasal dari bahasa Sasak dimana kaput berarti bungkus.Termasuk ke dalam klasifikasi hidangan pokok yang berbahan utama nasi.Di Desa Tempos Nasi Kaput ini dibungkus dengan daun pisang dan berbentuk kerucut, berbeda dengan di beberapa daerah di Lombok yang biasanya menggunakan kertas nasi dengan bentuk yang kerucut.
Gambar 14Laklak Serabi Sumber : Hasil Penelitian,2022Daerah lain di Lombok biasanya memanfaatkan metode yang tradisional tersebut sebagai daya tarik untuk meningkatkan minat konsumen, namun di Desa Tempos Serabi Laklak ini hanya disajikan diatas baki bersama jajanan yang lainnya.f.Kelaudan Berbahan utama tepung beras, berwarna hijau yang berasal dari air daun suji yang dimasak dengan cara dikukus.
ISSN No. 1978-3787 1291 Open Journal Systems ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... https://binapatria.id/index.php/MBI Vol.18 No.6 Januari 2024 Open Journal Systems pembangunan
ekonomi, sosial dan masyarakat.
1) Wisata KulinerMenurut Echols dan Shadily (dalam Putri,2012) menyatakan bahwa berdasarkan asal katapariwisata kuliner terdiri dari kata pariwisatayang berarti perjalanan seseorang atausekelompok orang dari satu tempat ke tempatyang lain dengan tujuan untuk bersenang-senang. Sedangkan kuliner berasal dari BahasaInggris yaitu culinary yang berarti berhubungandengan dapur atau masakan. Wisata kulinerberarti perjalanan wisata yang dilakukan olehseseorang atau melompok orang pada suatunegara atau daerah, dimana mereka(wisatawan) menikmati masakan khas negaraatau daerah yang dikunjungi.Terdapatbeberapa beberapa definisi lain dalam kegiatanwisata kuliner, Ignatov dan Smith (2006, dalamRedl, 2013) mendefinisikan wisata kulinersebagai suatu perjalanan wisata yang dilakukanoleh wisatawan dan selama perjalanan. Hal inibertujuan untuk konsumsi makanan daerah(termasuk minuman), atau pengamatan danstudi produksi makanan dan wisata kulinermenyangkut kepentingan dalam mencapaitujuan untuk mengetahui kebudayaan suatutempat melalui makanannya.Harvey (2012) juga memberikanpenjelasan bahwa wisata kuliner mampumenceritakan tentang warisan budaya,gambaran kehidupan masyarakat dan lansekapsuatu kawasan geografis. Selain itu jugamampu memperkaya pengalaman dan bisamenjadi alat yang berharga untuk mendorong
1978-3787 Open Journal Systems …………………………………………………………………………………………………….... ……………………………………………………………………………………………………... Vol.18 No.6 Januari 2024 https
METODE PENELITIANJenis penelitian ini adalah penelitiansurvei dengan metode deskriptif. Cohen danNomion (Sukardi,2003) mengungkapkanbahwa penelitian survey (survey) merupakankegiatan untuk mengumpulkan data denganbeberapa tujuan diantaranya mendeskripsikankeadaan apa adanya saat itu, mengidentifikasikeadaan saat ini untuk dibandingkan sertamenentukan hubungan sesuatu. Modelpenelitian survei dianggap paling baik karenapenelitian ini salah satunya memang bertujuanuntuk memperoleh dan mengumpulkan dataasli (original data) untuk mendeskripsikankeadaan.Penelitian ini dilakukan sepanjang jaluristirahat bersepeda di Desa Tempos,Kecamatan Gerung, Kabupaten Lombok Barat-Nusa Tenggara Barat. Lokasi ini dipilihkarena belakangan menjadi salah satu destinasiwisata alternatif pilihan di Lombok Baratsemenjak terekspos melalui akun media sosialDinas Pariwisata (Dispar) Kabupaten LombokBarat yang memiliki daya tarik kuliner lokalyang berpotensi untuk dikembangkan denganmemanfaatkan makanan tradisional yangdimiliki untuk menunjang potensi wisatakuliner sehingga perlu diinventarisasi dandigolongkan makanan tradisional yang dijualoleh pedagang untuk memberikan informasikepada wisatawan sehingga akan lebih eksisdalam mendukung kegiatan pariwisata.
Sedangkan bahan makanan nabati yang banyak digunakan dalam lauk pauk Indonesia yaitu tempe, tahu, oncom dan kacang kacangan.c.Sayur Sayur adalah suatu hidangan berkuah, yang dapat dimakan dengan atau tanpa nasi.Sayur biasanya berisi kuah dan bahan pokok sayuran atau dapat pula ditambahkan dengan bahan lain seperti bahan hewani atau tumbuh-tumbuhan.Bahan yang digunakan dalam masakan sayur dapat berupa air, kaldu, atau santan.Bumbu yang digunakan bisa bervariasi tergantung rasa yang diinginkan, karena bumbu yang digunakan tiap daerah berbeda-beda.ISSN No. ://binapatria.id/index.php/MBIOpen Journal Systems d.Buah-buahan Pasar di Indonesia penuh dengan berbagai jenis buah tropis.Buah adalah bagian penting dalam pola makan Indonesia, baik dimakan langsung, bias dijadikan kudapan manis (seperti es buah), disajikan menjadi masakan gurih atau pedas seperti rujak dan pisang goreng, diproses menjadi keripik seperti keripik nangka dan keripik pisang.Banyak jenis buah-buahan seperti manggis, rambutan, nangka, durian, dan pisang yang merupakan tanaman asli Indonesia.e. Sambal Sambal adalah hidangan yang tidak berdiri sendiri, tetapi harus dimakan dengan bahan lain, terutama lalap.Sambal juga dapat digunakan sebagai penambah rasa dan melengkapi hidangan lain.Sambal dapat diklasifikasikan menjadi dua yaitu sambal mentah dan matang.Sambal mentah contohnya sambal bawang, terasi, dan colocolo, sedangkan sambal matang contohnya sambal tomat, sambal teri dan sambal kacang.f.Makanan ringan atau kudapan Kudapan atau disebut juga sedap-sedapan adalah makanan kecil yang biasa dihidangkan bersama minuman, baik untuk keperluan sehari-hari maupun untuk kesempatan khusus.Kue khas Indonesia sering disebut sebagai jajan pasar.Indonesia memiliki kekayaan berbagai macam kudapan dan kue, baik gurih maupun manis.Kue populer diantaranya risoles, pastel, lumpia, lemper, tahu isi, lapis legit, getuk, bakpia, bika ambon, lupis, lemang, timpan, klepon, onde-onde, nagasari, soes, dan bolu kukus.Jenis jajanan sangat variatif dan sampai sekarang masih dilestarikan yaitu jajanan yang fungsinya selain dikonsumsi sendiri, dijual, pelengkap makanan sesaji untuk acara ritual (kenduri) ataupun acara tertentu.g.Minuman Minuman yang biasanya menjadi bagian dari kuliner tradisional adalah minuman sehari-hari seperti kopi, teh, wedang jahe, juga minuman penyegar dan jamu sebagai obat.Minuman Indonesia menurut jenisnya dibedakan menjadi dua yaitu minuman panas dan dingin.Minuman panas ada dua macam yaitu minuman panas tidak berisi (teh, kopi, coklat, jeruk) dan minuman panas berisi (bajigur, wedang ronde, sekoteng dan wedang ublek).Sedangkan, minuman dingin juga ada dua macam yaitu minuman dingin tidak berisi (es sirup, es limun, es beras kencur) dan minuman dingin berisi (dawet, es campur, es buah).
ISSN No. 1978-3787 1293 Open Journal Systems ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... https://binapatria.id/index.php/MBI Vol.18 No.6 Januari 2024 Open Journal Systems
ISSN No. 1978-3787 Open Journal Systems …………………………………………………………………………………………………….... ……………………………………………………………………………………………………... Vol.18 No.6 Januari 2024 https://binapatria.id/index.php/MBI Open Journal Systems
olah termasuk dalam klasifikasi sayurdalam makanan tradisional Indonesia.Jika biasanya pada daerah lain di PulauLombok, Olah-olah hanya disiramdengan bumbu atau saus yang dominanberwarna putih karena berbahan dasarsantan yang memang menjadi khasnyanamun di Desa Tempos para pedagangmenyajikan Olah-olah ini dengan sedikitberbeda yakni dengan bumbu yangcenderung berwarna merah dengantaburan kelapa parut yang sudahdibumbui.Gambar 9Pelecing Geranggang4. Makanan Ringan atau Kudapana. BangetHidangan yang termasuk ke dalamklasifikasi makanan ringan atau kudapandikarenakan Banget biasa disajikandengan minuman seperti kopi.Gambar 8Olah-olahSumber : Hasil Penelitian,2022c. Pelecing GeranggangYang membedakannya dengan Pelecing Kangkung hanya pada bahan utamanya yaitu Geranggang atau rumput laut. Biasa oleh para pedagang di Desa Tempos menyebutnya juga dengan Pelecing Rantai.Gambar 4 Sate Ampet Sumber : Hasil Penelitian,2022 Gambar 10 Banget Sumber : Hasil Penelitian, 2022 Jajanan pasar khas Lombok yang terbuat dari beras ketan hitam yang dimasak dengan cara dikukus dan di Desa Dalam menyajikan Sate Ampet, Tempos biasa disajikan dengan kelapa para pedagang di Desa Tempos parut dan saus gula merah. menggunakan bumbu yang mirip dengan bumbu Ayam Taliwang b. Lupis tetapi Sedikit berbeda dengan Lupis pada menggunakan santan yang lebih banyak sehingga lebih cair sebagai sausnya. daerah lain di Lombok, hidangan yangb. Pepes IkanBerbahandasarikantongkolmenjadikan hidangan ini masuk ke
biasanya terbuat dari beras ketan putih yang dibungkus menggunakan daun pisang dan dibentuk segitiga ini di Desa ISSN No.
1978-3787 1297 Open Journal Systems ……………………………………………………………………………………………………… ……………………………………………………………………………………………………... https://binapatria.id/index.php/MBI Vol.18 No.6 Januari 2024 Open Journal Systems
Tempos berbahan dasar beras ketanSumber : Hasil Penelitin,2022hitam.Terbuat campuran parutan singkongyang terdapat pisang ditengahnya laludimasaakdengancaradikukusmenjadikan Kedebak ini disajikan untukhidangan sarapan pagi di Desa Tempos.d. CerorotJenis klasifikasi kudapan satuini biasanya dijumpai saat upacara adatsuku Sasak tertentu di Pulau Lombokseperti acara pernikahan. Di DesaTempos bisa ditemukan setiap pagiyang biasa digunakan sebagai sarapan.Dibalut dengan daun kelapayang dibentuk mirip dengan terompetyang berukuran kecil. Daerah lain diGambar 11 LupisIndonesia Cerorot dikenal dengan Kue Mata Bor.Sumber : Hasil Penelitian,2022Dalam penyajiannya, Lupisdisajikan dengan kelapa parut dan gulamerah yang dimasak atau biasanyapedagang di Desa Tempos menyebutnyaEnten.c. KedebakPada daerah lain di Indonesiahidangan ini sering disebut KueKacamata atau Kue Mataroda. Namun diDesa Tempos hidangan ini disebutdengan nama Kedebak.Gambar 13CerorotSumber : Hasil Penelitian,2022e. Serabi LaklakHidangan yang terbuat daritepung beras, garam, air dan santankental. Cara pengolahannya masihmenggunakan metode tradisional yaitudengan tungku yang terbuat dari tanahliat, serta dipanggang menggunakankayu bakar.Gambar 12Kedebak
Budi Arif, Wurianto, Aspek Budaya Pada Tradisi Kuliner Tradisional Kota Malang. 2008Universitas Muhamadiyah Malang
Dinas Pariwisata, Lombok Barat, Pokdarwis Desa Tempos Sajikan Paket Mewah Bagi Goweser. 2021
Management coordinatr-Caribbean & Agrotourism Specialist. 13 th Annual Caribbean Confrence on Sustainable Tourism Develpment. Ena Harvey, 2012
. I A Putri, A Eka Trisna, Sri, F Sulistyawati, N M Suarka Dan, Ariani, 2012
. Open Journal Systems ……………………………………………………………………………………………………… ……………………………………………………………………………………………………. 1862024
. Open Journal Systems.
Culinary Tuorism For yung Adult Travellers and its connection to Destination Management. Sabrina Redl, 2013Thesis: Viena University
Food, place and authenticity: local food and the sustainable tourism experience. R Sims, 10.1080/09669580802359293Journal of Sustainable Tourism. 1732009
Peran Perempuan dalam Mengangkat Citra Kuliner Lokal di Kawasan Wisata Narmada. I Suteja, Wayan, Dkk, Jurnal Ilmiah Hospitality. 92020
Pedagang pukul sembilan' di Desa Tempos Lombok Barat minta tempat layak. Viki, 2021
| [
0.0031036657746881247,
-0.07699282467365265,
-0.047222163528203964,
0.04030338674783707,
-0.20683467388153076,
0.06302006542682648,
-0.09483826160430908,
0.1176735907793045,
-0.026745498180389404,
0.0968700647354126,
0.2791615128517151,
0.07107962667942047,
-0.029527651146054268,
-0.150527... |
Majalah Ilmiah dan Informasi Kegeografian
Andy Nugroho andy.n@mail.ugm.ac.id
Program Studi Magister Penginderaan Jauh Fakultas Geografi
Universitas Gadjah Mada
YogyakartaIndonesia
ProjoDanoedoro pdanoedoro@ugm.ac.id
Bowo Susilo bowosusilo@ugm.ac.id
Departemen Sains Informasi Geospasial Fakultas Geografi
Universitas Gadjah Mada
YogyakartaIndonesia
Surili Jawa
Taman Nasional
Gunung Merbabu
Javan Surili Mount
Merbabu National
Park Habitat
Maxent Spatial Model
Nasional Guung
Merbabu Berdasarkan Surat
Keputusan tersebut Taman Nasional Gunung Merbabu memiliki luas
5.820, 49 hektar yang mencakup Kabupaten MagelangSemarang
dan Boyolali Provinsi Jawa Tengah
Majalah Ilmiah dan Informasi Kegeografian
5C4989E0CF1CA0C92A58FE2815A614A2
Surili Jawa (Presbytis comate fredericae Sody, 1930) merupakan salah satu primata endemik yang dapat ditemui di kawasan Taman Nasional Gunung Merbabu (TNGMb).Habitat Surili Jawa terus mengalami tekanan dan gangguan yang disebabkan oleh kebakaran hutan dan aktivitas manusia.Sebagai bentuk tindakan konservasi, maka diperlukan informasi spasial mengenai persebaran habitat Surili Jawa melalui data Penginderaan Jauh dan Sistem Informasi Geografi (SIG).Penelitian ini bertujuan untuk membuat model spasial kesesuaian habitat Surili Jawa di kawasan TNGMb melalui data Penginderaan Jauh dan SIG.Penelitian ini dilakukan menggunakan metode species distribution modelling (SDM) dengan Maximum Entropy (Maxent).Variabel yang digunakan adalah data kehadiran, tutupan lahan, kerapatan vegetasi, kemiringan lereng, ketinggian tempat, jarak dari jalur pendakian, dan jarak dari tepi hutan.Hasil penelitian menunjukan luas wilayah yang sesuai untuk habitat Surili Jawa adalah 960,48 ha.Evaluasi kinerja model menunjukan akurasi nilai Area Under Curve (AUC) sebesar 0,887 dengan kategori baik.Hasil uji Jackknife menunjukan variabel yang memiliki kontribusi tinggi adalah jarak dari jalur pendakian, tutupan lahan, ketinggian tempat, dan kerapatan vegetasi.
Taman Nasional Gunung Merbabu (TNGMb) merupakan habitat bagi beberapa fauna endemik yang hanya dapat ditemui di wilayah tersebut.
Salah satu fauna yang mendiami Taman Nasional
Gunung Merbabu sebagai habitatnya adalah Surili Jawa (Presbytis comate fredericae Sody, 1930).
Surili Jawa merupakan salah satu dari banyak spesies primata Indonesia yang digolongkan ke dalam primate paling terancam punah (Nijman, 1997).Surili Jawa tersebar di beberapa kawasan seperti Gunung Slamet, Gunung Cupu, Gunung Sumbing, Gunung Sindoro, dan Gunung Merbabu (Supriatna dan Wahyono, 2000).Sebaran dari Surili Jawa menurut Nijman (1997) berada di Pulau Jawa bagian barat hingga berbatasan langsung dengan Jawa Timur yaitu Gunung Lawu.Beberapa pembedaan nama Surili terjadi di wilayah Jawa Barat dengan nama Surili (Presbytis comata Desmarest, 1822) dan Jawa Tengah dengan nama Surili Jawa (Presbytis comate fredericae Sody, 1930).International Union Conservation Nature (IUCN) mengkategorikan Surili Jawa sebagai endangered species atau spesies yang terancam punah sehingga menetapkan Surili Jawa sebagai spesies yang dilindungi (Nijman, 2020).Selain itu, Surili Jawa termasuk dalam Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) pada kategori Appendix II pada tahun 2016 yang secara internasional tidak boleh untuk diperdagangkan.
Masalah utama yang menjadi perhatian tentang upaya konservasi adalah pemahaman mengenai kesesuaian habitat bagi satwa yang dilindungi khususnya adalah Surili Jawa.
Permasalahan ini menyebabkan populasi Surili
Jawa terus mengalami penurunan habitat yang diakibatkan oleh bencana alam seperti kebakaran hutan dan aktivitas manusia terkait perubahan lahan sehingga menyebabkan menurunnya kualitas dan kuantitas habitat bagi Surili Jawa.
Perubahan habitat Surili Jawa di berada di Taman Nasional Gunung Merbabu (TNGMb) semakin lama semakin mengalami pengurangan luasan habitat.Penurunan luasan habitat Surili Jawa di Taman Nasional Gunung Merbabu dari tahun 2001 hingga tahun 2013 sebesar 1.037 hektar serta pengurangan tutupan hutan per tiap tahunnya sebesar 87 hektar/tahun (Alkaf et al., 2014).Selain itu, Salah satu penyebab berkurangnya luas tutupan lahan di Taman Nasional Gunung Merbabu adalah karena kebakaran hutan (Diyanti Isnaini, 2017).
Beberapa studi yang sudah dilakukan sebelumnya tentang kesesuaian habitat Surili Jawa yang ada di kawasan Taman Nasional Gunung Merbabu (TNGMb) menghasilkan wilayahwilayah yang memiliki potensi sebagai habitat Surili Jawa.Penelitian yang dilakukan Diyanti Isnaini (2017) menghasilkan luasan habitat optimum Surili Jawa pada tahun 2017 adalah sebesar 844 ha atau sekitar 15% dari total wilayah Taman Nasional Gunung Merbabu (TNGMb).
Selanjutnya, Latifiana dan Handayani (2019) menghasilkan luasan habitat Surili Jawa adalah sebesar 630,36 ha atau 10,76% dari luas Taman Nasional Gunung Merbabu (TNGMb).Pemodelan Pemodelan spasial untuk tingkat kesesuaian habitat Surili Jawa (Presbytis comate fredericae Sody, 1930)
Pengumpulan dan Analisis Data
Jarak dari Tepi Hutan
Jarak
Gambar 3. Persentase luas kerapatan vegetasi pada kawasan TNGMb
Gambar 5. Jarak dari tepi hutan pada kawasan TNGMb
Gambar 9. Grafik uji Jackknife pada ilai AUC
Lokasi Wilayah Penelitian Pemodelan Kesesuian Habitat dan Validasi Pemodelan disribusi Surili Jawa untuk pembuatan model kesesuaian habitat dilakukan
Andy Nugroho, dkk | Geomedia Vol 20 No 2 Tahun 2022 Pemodelan spasial untuk tingkat kesesuaian habitat Surili Jawa (Presbytis comate fredericae Sody, 1930) diTaman Nasional Gunung Merbabu (TNGMb)distance sehingga dapat diketahui pengaruh jarak Parameter Input(SDM). Model ini menggunakan variabel terdiri dari tutupan lahan, kerapatan vegetasi,terhadap kehadiaran Surili Jawa. Penggunaan euclidean distance diperuntukan untuk penentuan Max Number of 10.000 Background Pointlingkungan dan data kehadiran Surili Jawa sebagai input utama untuk menghasilkan model kawasan kemiringan dan ketinggian lereng, jarak dari jalur pendakian, dan jarak dari tepi hutan. Data variabeljarak tanpa adanya variabel halangan dengan Replicated Run Type Subsamplehabitat yang sesuai untuk Surili Jawa di TNGMb. ini menggunakan bentuk raster yang memilikiasumsi bahwa Surili Jawa secara langsung menghindari keberadaan manusia yang melakukan pendakian ataupun aktivitas di sekitar jalur pendakian. Ekstraksi informasi dari variabel Maximum Iteration 500 Convergence Threshold 0.00001 Output Format Logistic Sumber: Philliph dan Dudik ,2008Data yang diinputkan merupakan data continuous yang meliputi kemiringan lereng, ketinggian tempat, jarak dari jalur pendakian, dan jarak dari format ASCII dan menggunakan resolusi piksel yang sama yaitu 30 meter dengan cakupan wilayah yang sama. Variabel jarak diolah dengan tepi hutan, sedangkan data tutupan lahan dan menggunakan euclidean distance untuktersebut kemudian digunakan untuk pembuatan Evaluasi model yang dilakukan dalamkerapatan vegetasi merupakan data categorical menentukan seberapa jauh jarak dari jalurkesesuaian habitat bagi Surili Jawa dengan penelitian ini adalah dengan menggunakansehingga dipisahkan dalam pembuatan variabel pendakian dan jarak dari tepi hutan. Selain itu,menggunakan model Species Distribution Model metode Receiver Operating Charateristic (ROC).untuk model kesesuaian habitat Surili Jawa. data kehadiran Surili Jawa (presence) yangROC merupakan metode yang berdasarkandigunakan dalam penelitian ini bersumber padasensitivitas dan spesifisitas (Baldwin, 2009). Metode ROC dibangun dengan memilih beberapa data untuk dijadikan sampel. Model yang baik dapat didefinisikan oleh kurva yang memaksimalkan sensitivitas dengan nilai pecahan positif (Baldwin, 2009). Hal tersebut dapat diukur dengan menghitung Area Under Curve (AUC) (Fourcade et al., 2014). Prediksi lokasi kesesuaian habitat Surili Jawa Gambar 1. dengan menggunakan Species Distribution Model (SDM) yaitu Maximum Entropy (MaxEnt). Philliph dan Dudik (2008) menjelaskan bahwa pemodelan dengan menggunakan MaxEnt menghasilkan model dengan akurasi yang tinggi hanya dengan data kehadiran spesies. Selain itu, penggunaan dibangun menggunakan pengulangan sebanyak 10 kali dengan tipe ulangan subsample. Nilai AUC memiliki rentang 0 sampai 1, dengan nilai mendekati 1 berarti memiliki kinerja model yang optimal dan nilai dibawah 0.5 berarti memiliki kinerja model yang kurang optimal. Araújo dan Gusian (2006) mengkasifikasikan nilai AUC untuk menilai kinerja model prediksi seperti pada Tabel Transformasi yang digunakan untuk pembuatan 2. kerapatan vegetasi adalah transformasi indeks Tabel 2. Kinerja model berdasarkan vegetasi Normalized Different Vegetation Index nilai AUC Nilai AUC (NDVI). Kinerja Model 0.9 -1.0 Berdasarkan hasil transformasi indeks Sangat Baik 0.8 -0.9 vegetasi tersebut nilai NDVI memiliki rentang Baik 0.7 -0.8 antara -0.012447 hingga 0.596952 dengan rerata Sedang 0.6 -0.7 0.118008. Hasil dari indeks NVDI Kurang Baik direpresentasikan pada rona citra dari gelap Sumber: Araújo dan Gusian (2006) hingga terang dan memiliki nilai dengan rentang -hasil pengamatan lapangan dan data historis Penelitian ini merupakan penelitian terapan kehadarian Surili Jawa di Taman Nasional Gunung dengan pendekatan kuantitatif dengan metode Merbabu (TNGMb). Data kehadiran Surili Jawa penginderaan jauh dan sistem informasi geografis yang digunakan sebanyak 31 temuan dari tahun yang digunakan untuk mendapatkan hasil berupa 2011 hingga tahun 2022. turunan informasi tutupan lahan dan variabel terkait pembuatan kesesuaian habitat Surili Jawa (Presbytis comate fredericae Sody, 1930) di kawasan Taman Nasional Gunung Merbabu Tutupan Lahan Klasifikasi tutupan lahan dilakukan menggunakan metode terbimbing (supervised) (TNGMb) menggunakan citra satelit Landsat 8 Operation Land Imager (OLI). Pengambilan sampel di lapangan dalam penelitian ini menggunakan metode sampling yaitu stratified random sampling untuk pengambilan sampel tutupan lahan dan kehadiran Surili Jawa. Ekstraksi informasi dari citra meliputi ekstraksi informasi tutupan lahan vegetasi menggunakan teknik interpretasi digital yaitu klasifikasi multipektral. Klasifikasi multispektral bertujuan untuk mengidentifikasi tampilan objek pada citra sesuai dengan nilai spektralnya. Jenis klasifikasi yang digunakan adalah klasifikasi terbimbing atau supervised classification dengan teknik maximum likelihood. Tahapan selanjutnya adalah pembuatan transformasi indeks vegetasi NDVI dari citra Landsat yang berguna untuk analisis kerapatan untuk hasil sampel spesies dan format (. ascii) untuk prediktor variabel fisik. Parameter standar yang digunakan untuk menjalankan MaxEnt merupakan paramater baku yang sudah ditetapkan untuk pembuatan model probabilitas kehadiran berdasarkan data kehadiran. Parameter ini terbagi menjadi dua bagian yaitu basic dan advance yang digunakan untuk menjalankan MaxEnt. Parameter dapat pengukuran kerapatan vegetasi dilapangan dengan menggunakan persamaan regresi dan menguji kekuatan hubungan dari nilai NDVI dengan nilai kerapatan vegetasi dilapangan dengan menggunakan korelasi Pearson. Kelas kerapatan vegetasi dapat dilihat pada Tabel 3. Hasil dari persamaan regresi memiliki koefisien determinasi (R 2 ) sebesar 0,5028 dengan nilai korelasi pearson sebesar 0,7090 serta tanaman, semak dan belukar, padang memiliki nilai Root Mean Square Error (RMSE) rumput/sabana, lahan pertanian, dan lahan sebesar 0,2314. Nilai ini kurang dari 0.5 sehingga terbangun. hasil dari RMSE ini dapat ditoleransi dan dapat Hasil uji akurasi tutupan lahan keseluruhan digunakan untuk analisis selanjutnya. Peta memiliki nilai overall accuracy sebesar 91,20% persentase luas kerapatan vegetasi dapat dilihat dengan nilai koefisiensi kappa sebesar 0,88. Selain pada Gambar 3. itu, hasil dari akurasi produser (Producer Accuracy) memiliki nilai tertinggi untuk tutupan lahan hutan Tabel 3. Kelas Kerapatan VegetasiMaxEnt dikaitkan dengan variabel fisik yang mendukung hadirnya suatu spesies di lokasi tertentu. Proses pengolahan MaxEnt diawali dengan pembuatan layer -layer variabel yang sebelumnya sudah diolah. Format yang digunakan untuk pengolahan MaxEnt adalah format (.csv) Penyusunan Variabel Lingkungan Prediksi kehadiran Surili Jawa di Taman Nasional Gunung Merbabu (TNGMb) dilakukan 1 hingga 1, dimana semakin gelap akan menunjukkan tutupan tajuk yang rendah atau jarang dan semakin terang akan menunjukan dengan menggunakan data kehadiran Surili Jawa dan data spasial variabel lingkungan yang berpengaruh terhadap kehadiran Surili Jawa.vegetasi di lokasi penelitian. Pada tahapan ini juga dihasilkan kemiringan lereng dan elevasi dari hasil ekstraksi citra DEM SRTM. Selain itu, beberapa variabel lingkungan seperti jarak dari tepi hutan, dan jarak dari jalur pendakian juga diekstraksi dengan citra Landsat 8. Pengolahan variabel jarak dilihat pada Tabel 1. Tabel 1. Parameter standar pada MaxEnt Parameter Input Random Test Percentage Nilai NDVI Kerapatan Vegetasi tanaman adalah 100% dan nilai terendah untuk -0,0124 -0,0891 Non vegetasi tutupan lahan area terbangun sebesar 58,13%. 0,0891 -0,1906 Rendah 0,1906 -0,2922 Agak rendah 25 Replicates 0,2922 -0,3938 Sedang 10 Regulation Multiplier 0,3938 -0,4953 Rapat 1 0,4953 -0,5969 Sangat rapatBeberapa variabel lingkungan yang digunakandilakukan dengan menggunakan proses euclidean Sumber: Analisis data, 2022Geomedia : Majalah Ilmiah dan Informasi Kegeografian |71 72| Geomedia : Majalah Ilmiah dan Informasi Kegeografian
dengan algoritma maximum likelihood pada citra Landsat 8 OLI.Klasifikasi tutupan lahan berguna untuk memperoleh variabel lingkungan yang akan digunakan sebagai masukan pada proses pemodelan spasial dengan MaxEnt.Selain itu, klasifikasi tutupan lahan dilakukan untuk memperoleh informasi jarak dari tepi hutan.Kelas tutupan lahan yang ada pada citra Lansat diwilayah penelitian dapat diidentifikasi menjadi hutan pegunungan, hutan lahan tinggi, hutan Nilai akurasi pengguna (User Accuracy) memiliki nilai tertinggi sebesar 100% untuk kelas hutan tanaman dan nilai terendah sebesar 78,49% untuk kelas lahan pertanian Berdasarkan hasil klasifikasi tutupan lahan proporsi luas masing -masing Andy Nugroho, dkk | Geomedia Vol 20 No 2 Tahun 2022 Geomedia : Majalah Ilmiah dan Informasi Kegeografian |73 tutupan lahan adalah 2326,77 ha pada hutan pegunungan, diikuti hutan lahan tinggi 1935,60 ha, hutan tanaman 803,98 ha, semak dan belukar 498,10 ha, padang rumput/sabana 427 ha, lahan pertanian 301,15 ha, dan lahan terbangun 38,58 ha.Peta tutupan lahan dapat dilihat pada Gambar 2. Gambar 2. Tutupan lahan pada kawasan TNGMb Kerapatan Vegetasi Kerapatan vegetasi digunakan dalam aspek vegetasi dengan memanfaatkan kombinasi antara dua saluran yaitu saluran merah dan saluran inframerah dekat, dimana kedua saluran ini memiliki kepekaan yang tinggi dalam menyerap gelombang.Kerapatan vegetasi dalam penelitian ini merepresentasikan tutupan tajuk yang digunakan oleh Surili Jawa sebagai tempat mencari makan dan tempat untuk belindung dari serangan hewan buas serta berpindah tempat.tutupan tajuk yang semakin rapat.Hasil dari indeks vegetasi ini kemudian digunakan untuk penentuan kelas kerapatan vegetasi dengan observasi lapangan berdasarkan nilai NDVI sehingga dapat digunakan untuk membangun model kerapatan vegetasi dilapangan.Nilai kerapatan vegetasi didapatkan dengan cara menghubungkan nilai NDVI citra dengan hasil
Model spasial perubahan penggunaan lahan di Taman Nasional Gunung Merbabu dan daerah penyangganya. M Alkaf, K Munibah, O Rusdiana, 2014
. Majalah Ilmiah Globe. 161
Zonasi Taman Nasional Gunung Merbabu. Direktorat Jenderal Perlindungan Hutan dan Konservasi alam. M B Araújo, A Guisan, 10.1111/j.1365-2699.2006.01584.xJournal of biogeography. 33102006. 2014Kementerian Lingkungan Hidup dan KehutananFive (or so) challenges for species distribution modelling
Use of Maximum Entropy Modeling in Wildlife Research. R Baldwin, 10.3390/e11040854Entropy. 1142009
Predicting Dynamics of the Potential Breeding Habitat of Larus saundersi by MaxEnt Model under Changing Land-Use Conditions in Wetland Nature Reserve of Liaohe Estuary. Y Chang, C Chang, Y Li, M Liu, J Lv, Y Hu, 10.3390/rs14030552China. Remote Sensing. 1435522022MDPI AG
Analisis Daerah Rawan Kebakaran Hutan Pada Habitat Optimum Surili Jawa (Presbytis Fredericae Sody, 1930) Di Taman Nasional Gunung Merbabu. S Diyanti Isnaini, Jawa Tengah. Tesis. Program Studi Ilmu Lingkungan Universitas Gadjah Mada. 2017
A review of methods for the assessment of prediction errors in conservation presence/absence models. A H Fielding, J O H N F Bell, 10.1017/S03768929970Environmental Conservation. 2411997
Mapping Species Distributions With MAXENT Using A Geographically Biased Sample Of Presence Data: A Performance Assessment Of Methods For Correcting Sampling Bias. Y Fourcade, J O Engler, D Rödder, J Secondi, 10.1371/journal.pone.0097122PLoS ONE. 95e971222014
Prediksi Kesesuaian Habitat Surili Jawa (Presbytis comata) di Taman Nasional Gunung Merbabu. K P Handayani, K Latifiana, Jurnal Primatologi Indonesia. 1612019
Preferensi habitat surili di Taman Nasional Gunung Ciremai. Agus Kusumanegara, A P Kartono, L B Prasetyo, Media Konservasi. 2212017
AUC: a misleading measure of the performance of predictive distribution models. J M Lobo, A Jiménez-Valverde, R Real, 10.1163/26660644-06604005Mammalia: Primates: Cercopithecidae) in Java. Indonesia2008. 1997. Desmarest, 182217Bijdragen Tot de Dierkunde
Analisis Pola Penggunaan Ruang dan Parameter Demografi Macan Tutul Jawa di Taman Nasional Gunung Pemodelan spasial untuk tingkat kesesuaian habitat Surili Jawa (Presbytis comate fredericae Sody, 1930) di Taman Nasional Gunung Merbabu (TNGMb) 84| Geomedia : Majalah Ilmiah dan Informasi Kegeografian Ciremai. Tesis. Program Pasca Sarjana Institut Pertanian Bogor. V Nijman, A Setiawan, 10.2305/IUCN.UK.2020-2.RLTS.T18125A17955175.enPresbytis comata. The IUCN Red List of Threatened Species 2020: e.T18125A17955175. Studi Kasus di Suaka Margasatwa Kuala Lapak Kabupaten Barito Kuala Provinsi Kalimantan Selatan. Bogor M, Muhaimin; YogyakartaNasalis larvatus Wurmb2020. 2013. 2017Pemodelan Spasial Untuk Analisis Tingkat Kesesuaian Habitat BekantanTesis. Fakultas Geografi UGM
Modeling of species distributions with Maxent: new extensions and a comprehensive evaluation. S J Phillips, M Dudík, J Tilson, R Gurmaya, K J Manansang, J Wardojo, W Sriyanto, A , . . Seal, U , 10.1111/j.0906-7590.2008.5203.xJavan gibbon and Javan langur: Population and habitat viability analysis report. Apple Valley. Minnesota2008. 199431World Conservation Union/Species Survival Commission Captive Breeding Specialist Group
Panduan Lapangan Primata Indonesia. J Supriatna, E H Wahyono, 2000Yayasan Obor Indonesia. Jakarta
Seleksi Habitat Oleh Rekrekan (Presbytis frederiace Sody, 1930) di Taman Nasional Gunung Merbabu. Syarifah, Tesis. Fakultas Kehutanan Universitas Gadjah Mada. Yogyakarta2013
Studi Kohabitasi Penggunaan Ruang Lutung Jawa Dengan Surili di Taman Nasional Gunung Ciremai Provinsi Jawa Barat. Wakidi, Tesis. Institut Pertanian Bogor. 2013
| [
0.12738864123821259,
0.012392817065119743,
0.01853545568883419,
0.03998788818717003,
-0.10404340922832489,
-0.05707928165793419,
-0.10074836760759354,
0.08887982368469238,
-0.017401019111275673,
0.11588066816329956,
0.11427478492259979,
-0.12427464127540588,
0.08142358809709549,
0.04229640... |
63rd ASH Annual Meeting Abstracts ORAL ABSTRACTS 901.HEALTH SERVICES RESEARCH-NON-MALIGNANT CONDITIONS Drepadom -Establishment of Home Care Services and Hospitalizations for Sickle Cell Disease Patients As Standard Care Since the Covid-19 Pandemic
2021
Yanís Pelinski
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Cindy Mescam
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Christian Kassasseya
IMRB -Inserm U955 Transfusion et maladies du globule rouge (Equipe
Etablissement Français du Sang
APHP Hôpital
Creteil, CreteilFrance, France
Gonzalo De Luna
Sickle cell referal Center
APHP Hôpital Henri Mondor
France 4 sickle cell referral centerCreteil, CreteilFrance
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Henri Guillet
Clara Noizat
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Sylvain Lejeune
APHP Centre Hospitalo-Universitaire Avicenne
Bobigny, BobignyFrance, France
Suella Martino
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Dora Bachir
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Françoise Driss
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
APHP Hôpitaux universitaires de Paris Sud-Bicêtre
Le Kremlin-Bicêtre, Le Kremlin BicêtreFrance, France
Amna Jebali
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Anne-Laure Pham
Hung D'alexandry D'orengiani
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Nicolas Lemonier
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
France Pirenne
Etablissement Français du Sang
CreteilFrance
Anoosha Habibi
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Pablo Bartolucci
APHP Hôpital Henri Mondor
Creteil, CreteilFrance, France
Henri Mondor
63rd ASH Annual Meeting Abstracts ORAL ABSTRACTS 901.HEALTH SERVICES RESEARCH-NON-MALIGNANT CONDITIONS Drepadom -Establishment of Home Care Services and Hospitalizations for Sickle Cell Disease Patients As Standard Care Since the Covid-19 Pandemic
Blood
138202110.1182/blood-2021-147740Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.
Abstract INTRODUCTION Vaso-occlusive crisis (VOC), hallmark of sickle-cell disease (SCD), is the rst cause of patients' emergency room (ER) admissions and hospitalizations. Acute chest syndrome (ACS) is a life-threatening complication that can occur during VOC and prolong hospitalization and is one of the main causes of death in SCD patients. The PRESEV score, established by team members and colleagues, assesses the risk of developing ACS (Bartolucci et al., 2016). In addition, the score has been validated by an international multicenter study, involving 13 centers, distributed in ve different countries (PRESEV 2 -ASH 2020). Throughout the rst wave of the Covid-19 pandemic, VOC management for SCD patients was a major concern. Our sickle cell referral center set up a hotline to monitor patients suffering from VOC daily, and organized the deployment of home-care services when required. The success of this system during the rst wave of the pandemic led to the establishment of DREPADOM, a home-care and hospitalization protocol for VOC management in patients who are at a low risk of developing ACS, as standard care. DESCRIPTION OF SETTING Patients eligible for DREPADOM are patients that arrive at the ER for a VOC with a low PRESEV score, meaning low risk of developing ACS; or patients that are discharged early following hospitalization for VOC. After physical examination and calculation of the PRESEV score, DREPADOM home hospitalization is systematically offered to patients arriving to the ER with a PRESEV score ≤ 5. If the patient agrees, the DREPADOM nurse coordinator then acts as a link between the pharmacist, the oxygen supplier, the homecare provider, and the DREPADOM medical platform to activate the home hospitalization protocol. This entails the delivery of oxygen supply at the patient's house, dispatch of a medical prescription of opioids and parenteral treatments, twice/thrice-daily visits from homecare nurses, and an on-call SCD expert. DREPADOM relies on a system of daily telephone calls with three levels of expertise and warning and a decision-making algorithm. This is supervised by SCD experts, who arbitrate according to the evolution of the situation (stopping the follow-up, continuing the follow-up as an outpatient, hospitalization) (Fig.1). Furthermore, nurses enter patient vitals in real-time during their daily visits on a dedicated online platform (Link4Life) that contains an integrated automatic alert system. Additionally, a daily phone update between the DREPADOM coordination and the homecare provider's coordination concerning status and evolution of the patient's global condition takes place. RESULTS Over a 6-month period, 39 patients were included in the DREPADOM home hospitalization protocol, 3 of which were included multiple times for a total of 42 inclusions. Mean age was 40 years old [±9], sex ratio was 14/25 (male/female), ER vs early discharge ratio was 21/22, and mean homecare follow-up was 3 days (±1) for both, patients arriving from the ER and early discharge patients. Throughout the third wave of the pandemic, when hospital saturation was a major concern, patients with PRESEV scores 5 ≤ 11 were also offered DREPADOM. Three patients were hospitalized (7%): one for an ACS, who was included during the 3 rd wave of the pandemic with a PRESEV score of 8; one for pyelonephritis unrelated to the VOC; and one for dif culties with venous access. No death was reported. PERSPECTIVES Preliminary satisfaction surveys show a great enthusiasm for DREPADOM, partly due to the high standard of care received, but also due to the shorter length of hospitalization. In fact, median hospital stay for VOC is 4 [3-7] days (Bartolucci, 2016) whereas median homecare follow-up was 3 [1-6] days.
Disclosures Bartolucci: Hemanext: Consultancy; Jazz Pharma: Other: Lecture fees; AGIOS: Consultancy; F. Hoffmann-La Roche Ltd: Consultancy; Emmaus: Consultancy; GBT: Consultancy; INNOVHEM: Other: Co-founder; Bluebird: Consultancy, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Lecture fees, Steering committee, Research Funding; Addmedica: Consultancy, Other: Lecture fees, Research Funding; Fabre Foundation: Research Funding. https://doi.org/10.1182/blood-2021-147740 Figure 1
NOVEMBER 2021 | VOLUME 138, NUMBER Supplement 1 © 2021 by The American Society of Hematology
NOVEMBER 2021 | VOLUME 138, NUMBER Supplement 1 ABSTRACTS
| [
0.04963476583361626,
-0.00728583475574851,
-0.0743323415517807,
-0.03948396444320679,
-0.07607707381248474,
0.03161849081516266,
-0.057581789791584015,
0.18372133374214172,
0.04014180228114128,
0.030964910984039307,
0.025523286312818527,
0.022512361407279968,
0.0380118228495121,
-0.0759165... |
Fr101 COVID19 PATIENTS IN A TERTIARY HOSPITAL IN WASHINGTON DC: EFFECTS OF COMORBIDITIES AND GASTROINTESTINAL SYMPTOMS ON OUTCOME
Hassan Brim
Philip Oppong-Twene
MohdNuri Tamanna
Elmugtaba Ibrahim
Lisa N Umeh
AbdoulEsther S Moon
Madjid Kone
Abigail Banson
Cassandra Federman
Farshad Aduli
Adeyinka O Laiyemo
Folake O Adeleye
Maryam Mehdipour Dalivand
Babak Shokrani
Gholamreza Oskrochi
Antonio Pizuorno
Angesom Kibreab
Sahar Nikdel
Eyitope Awoyemi
Derek Scholes
Edward L Lee
Zaki A Sherif
Hassan
Fr101 COVID19 PATIENTS IN A TERTIARY HOSPITAL IN WASHINGTON DC: EFFECTS OF COMORBIDITIES AND GASTROINTESTINAL SYMPTOMS ON OUTCOME
Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. Ashktorab Background: Coronavirus disease 2019 (COVID19) disproportionately struck minority popu-lations. It is important to find out the determinants of such differences in outcomes. Methods: We collected data on 403 hospitalized COVID19 patients at Howard University Hospital.
Background: Coronavirus disease 2019 (COVID19) disproportionately struck minority populations. It is important to find out the determinants of such differences in outcomes. Methods: We collected data on 403 hospitalized COVID19 patients at Howard University Hospital. Statistical analysis of symptoms, comorbidities, and lethality was performed using SPSS. Results: There were 257 (63.7%) African Americans (AAs), 102 (25.3%) Hispanics, and 26 (6.45%) Whites. The mean age was 55.6 years old (+/-18.5). However, the Hispanic's mean age was the lowest (43.66 years vs. 61.23 for Whites vs. 60 for AAs). 64 (15.8%) patients died. Age and race were risk factors for poor outcomes. Elevated Creatinine, Ferritin, CRP and D-dimers were associated with death (35.75% vs. 2.61%), (24.72% vs. 9.9%), (22.7% vs. 7.8%), and (21% vs. 0%), respectively. Hydroxychloroquine treatment did not associate with a better prognosis (25.92% vs. 14.23%). Abdominal pain, anorexia, diarrhea, nausea, and vomiting did not have any effect on the outcome. Elevated liver enzymes associated with poor outcome. There was more mortality in patients with cardiac diseases (25.67% vs. 14.33). Immunocompromised patients had a higher mortality rate (40% vs. 15.31%). Cough and fever were the top symptoms in our patients, but they were unrelated to the outcome. As for treatment, patients receiving glucocorticoid displayed higher mortality (39.1% vs. 11.8%). Also, patients with shortness of breath (21.6 vs. 7.3%), those undergoing Intubation (66.6% vs. 14.5%), and mechanical ventilation (70.1% vs. 5.1%) had a high mortality rate. Conclusion: Overall, elevated liver enzymes, ferritin, CRP, and D-dimers are robust markers of poor prognosis. The African Americans in our study displayed the highest mortality as they consisted of an older population when compared to the Hispanic group. GI symptoms did not correlate with outcome, however, they are likely important to follow as the virus persists within the GI system, even after clearing from the respiratory system. Background and Aims: The COVID-19 pandemic has created challenges in safely and effectively caring for patients with Inflammatory Bowel Disease (IBD). In this study, we surveyed patients with IBD to highlight the impact of the pandemic on their well-being, IBD symptoms and treatment. Methods: In a multi-site survey, 75 questions were administered to patients with IBD from June 26 to September 19, 2020. We evaluated patients' symptoms during the pandemic, medication changes, and the likelihood for in-person medical care. We also assessed nutrition, sleep patterns, stress level, and patients' feelings of vulnerability. Sensitivity analyses were done to outline the differences between participants based on their age (younger vs. older than 50-year-old), gender, history of anxiety, history of depression, and if the patient was living with someone at high risk for COVID-19. Logistic, ordinal, and linear regression models were utilized to perform sensitivity analyses. Results: Of 391 surveyed patients, 21.1% reported worsened gastrointestinal symptoms since the start of the pandemic. Regarding IBD management,17.5% reported changing biologic medication infusion schedule,18.7% reported medication changes, and 30.3% reported postponing IBD-related laboratory tests. Additionally, 16.5% reported a less healthy diet, 40.5% reported worsening sleep, 63.7% reported more stress, and 65.3% reported feeling more vulnerable than before the pandemic. The survey responses are summarized in figures 1 and 2. Female patients and patients with anxiety and depression tend to have worse outcomes regarding symptoms, IBD management, daily functioning, and emotional well-being.
S-219
AGA Abstracts
Conclusion: This study demonstrates significant associations between gender, anxiety, and depression with the ability to cope with the evolving COVID 19 pandemic. With this information, it would be feasible to identify those patients with underlying anxiety or depression to better tailor outreach and follow up to support these patients.
Fr103
STRATIFYING THE IMPACT OF COVID-19 PANDEMIC ON THE EMOTIONAL AND PHYSICAL WELL-BEING OF PATIENTS WITH INFLAMMATORY BOWEL DISEASE.
Mohammed El-Dallal, Ariana Saroufim, Hannah Systrom, Sarah Ballou, Adam S. Cheifetz, Joseph D. Feuerstein
Background and Aims: Psychological stress is a known risk factor for relapse and worsening symptoms for patients with Inflammatory bowel disease (IBD) and could negatively affect the disease course. The COVID-19 pandemic has created ongoing distress since it started at the end of 2019. In this study, we utilized the Pandemic Emotional Impact Scale (PEIS) to stratify patients with IBD who have been impacted in terms of their well-being and IBD management. Methods: In a multi-center survey study, a 75-item questionnaire, that incorporated the PEIS, was administered to patients with IBD from June 26 to September 19, 2020. The PEIS was developed during the COVID-19 pandemic and consists of 16 questions that assess the emotional impact of the pandemic. Each of 16 items are scored on a 0-4 scale (0="Not at all", 1="A little bit", 2="Moderately", 3="A lot" and 4="Extremely") with the total PEIS score ranging between 0 to 64. Wilcoxon rank sum test and Kruskal-Wallis test were used to examine the association between the PEIS and measures of emotional well-being (sleep patterns, stress level, and vulnerability), changes in IBD symptoms, and the likelihood of IBD patients to visit medical facilities after the reopening. Results: Most of the patients chose to answer "Not at all", "A little bit", and "moderately" and were less likely to choose "A lot" and "Extremely" in most of the categories (Figure 1). The mean PEIS score for the entire population was 21.16 (95% CI 19.98_22.36). Female patients, patients with anxiety, and patients with depression were noted to have a significantly higher PEIS score than other patients. Using nonparametric testing, high PEIS was significantly associated with poor sleep, feeling more stressed, feeling more vulnerable, and worsening GI symptoms (abdominal pain and bowel habits). Additionally, PEIS score was significantly higher in patients who reported that they would avoid or be less likely to schedule visits to the GI clinic, GI procedures, or imaging studies after the reopening (Figure 2). Conclusion: Increasing PEIS score was associated with substandard emotional and physical outcomes in patients with IBD. Utilizing the PEIS score as a screening tool could help better tailor outreach and follow-up to support patients with IBD who have been impacted the most.
Fr101COVID19
PATIENTS IN A TERTIARY HOSPITAL IN WASHINGTON DC: EFFECTS OF COMORBIDITIES AND GASTROINTESTINAL SYMPTOMS ON OUTCOME Hassan Brim, Philip Oppong-Twene, Nuri Tamanna, Mohd Elmugtaba Ibrahim, Lisa N. Umeh, Esther S. Moon, Abdoul Madjid Kone, Abigail Banson, Cassandra Federman, Farshad Aduli, Adeyinka O. Laiyemo, Folake O. Adeleye, Maryam Mehdipour Dalivand, Babak Shokrani, Gholamreza Oskrochi, Antonio Pizuorno, Angesom Kibreab, Sahar Nikdel, Eyitope Awoyemi, Derek Scholes, Edward L. Lee, Zaki A. Sherif, Hassan Ashktorab
Fr102ASSESSING THE REPERCUSSIONS OF COVID-19 PANDEMIC ON DISEASE MANAGEMENT, PHYSICAL, AND EMOTIONAL WELL-BEING IN PATIENTS WITH INFLAMMATORY BOWEL DISEASEMohammed El-Dallal, Ariana Saroufim, Hannah Systrom, Sarah Ballou, Adam S. Cheifetz, Joseph D. Feuerstein
| [
0.04012904316186905,
-0.0301460362970829,
-0.0976497083902359,
0.058495327830314636,
-0.0015018745325505733,
0.0738944262266159,
-0.103953517973423,
0.15291891992092133,
0.09378092736005783,
-0.059621818363666534,
0.05760312080383301,
-0.040726855397224426,
0.02721211314201355,
0.016578443... |
In vitro growth of different chrysanthemum cultivars on murashige and skoog medium modified with some organic additives
R Firgiyanto
Department of Agricultural Production
Politeknik Negeri Jember
F Rohman fadil.rohman@polije.ac.id
Department of Agricultural Production
Politeknik Negeri Jember
In vitro growth of different chrysanthemum cultivars on murashige and skoog medium modified with some organic additives
F264B449C5476ABF85BCC18A450C4F2010.1088/1755-1315/1338/1/012006
Mass in vitro propagation of chrysanthemum plants requires large amounts of Murashige and Skoog (MS) media.In order to increase efficiency of MS media usage, the addition of organic materials and the selection of cultivars need to be studied.This study aimed to obtain the best modified MS media and cultivars for in vitro propagation of chrysanthemums.This research was conducted from July to September 2023 at tissue culture laboratory of Politeknik Negeri Jember.This study used Completely Randomized Design with two factors.The first factor was the chrysanthemum cultivars, i.e.Naweswari Agrihort and Suciono Agrihort.The second factor was the modified MS media, i.e.MS, ½MS + 50 g/l banana, ½MS + 50 ml/l coconut water and ½MS + 50 g/l sweet potato.Each combination of treatments was thrice repeated.Observation variables were plant height, time of shoot emergence, the number of shoots and the number of leaves.Data analysis was carried out using ANOVA and DMRT.The best modified media was ½MS + 50 g/l sweet potato that showed significantly higher plant compared to other treatments.The addition of the tested organic materials could reduce MS media usage by 50%.
Introduction
Chrysanthemums are an ornamental plant commodity that is widely cultivated in Indonesia because they have visual beauty and promising market potential both in the form of cut flowers and potted flowers.Chrysanthemums are widely used for room decoration because they can grow in 75% of full light intensity and can be the air purifier [1].Chrysanthemum production centers in Indonesia were North Sumatra, West Java, Central Java, East Java and South Sulawesi.As much as 79.91% of chrysanthemum production in East Java was supplied from Pasuruan Regency, amounting to 94,425,001 stalks [2].However, chrysanthemum production in Indonesia from 2019 to 2021 decreased by 26.07%, namely from 465,359,952 stalks to 344,031,088 stalks [3].Therefore, chrysanthemum production in Indonesia needs to be increased.
Propagation of chrysanthemum plants can be done generatively or vegetatively.Generative breeding causes segregation which produces plants with diverse flowers [4], even though flower uniformity is one of the important criteria in marketing chrysanthemum plants.The increasing demand for chrysanthemums requires producers to be able to provide uniform and disease-free chrysanthemum seedlings in large quantities and in a short time.Therefore, culturing efforts using in vitro culture techniques can be an alternative [5].Propagation by in vitro culture also does not require too much space and donor plants for propagation material [6].
The growth medium commonly used for in vitro propagation of chrysanthemums is Murashige and Skoog (MS).MS media will be needed a lot at the multiplication stage to produce plantlets in large numbers.In order to increase the effectiveness and efficiency of chrysanthemum propagation, MS media needs to be modified by adding plant growth regulators (PGR) and organic materials.MS media can be modified by adding growth regulators derived from inorganic or organic materials in order to produce lots of shoots in a short time [7][8][9].Besides that, genetic factors in chrysanthemums also influence the characteristics of plantlets produced from propagation through in vitro culture.½ MS in vitro culture media added with 50 g/l sweet potato significantly increased the number of leaves (8.75 blades) and the number of roots (4.10 strands) of chrysanthemum plants compared to the addition of 150 g/l banana at 8 weeks after planting.However, on ½ MS media supplemented with 50 g/l purple sweet potato, explants derived from Puspita Pelangi cultivar showed significantly higher plant growth (9.74 cm) and a greater number of leaves (8.75 blades) than Puspita Nusantara cultivar [10].
Chrysanthemum cultivators are currently required to be able to provide high quality seedlings in large quantities and in a short time to meet consumer demand.Therefore, research on effective and efficient modification of in vitro culture media for the production of superior plantlets in several chrysanthemum cultivars needed to be carried out.This study aimed to obtain the best cultivar and modified media to produce superior chrysanthemum plantlets through in vitro propagation.
Methods
Site and Materials
Research was conducted from July to September 2023 at the Tissue Culture Laboratory of Politeknik Negeri Jember.Explants were stem from sterile chrysanthemum plantlets.Every three explants were planted in a jar containing MS media with modifications according to research treatments.The jar in which the explants had been planted was placed in the incubation room at a temperature of 27 o C and air humidity of 53%.
Treatments
This research used completely randomized design with two factors.The first factor was the chrysanthemum cultivars, i.e.Naweswari Agrihort and Suciono Agrihort.The second factor was the modified MS media, i.e.MS (control), ½ MS + 50 g/l banana, ½ MS + 50 ml/l coconut water and ½MS + 50 g/l sweet potato by dissolving 50 g banana, 50 ml coconut water and 50 g sweet potato each in 1 liter of media containing half the composition of MS media.Each combination of treatments was repeated three times.Each experimental unit consisted of three jars, each containing three plants.
Observations and Data Analysis
Observations variables were plant height, time of shoot emergence, the number of shoots and the number of leaves.Data were analyzed using analysis of variance (ANOVA).Significant means were further analyzed using Duncan's Multiple Range Test (DMRT).Data analysis was carried out using SAS 9.4 software.
Results and Discussion
The Suciono Agrihort cultivar chrysanthemum plants showed significantly higher stem growth compared to the Naweswari cultivar chrysanthemum plants from 21 to 56 days after planting in vitro (Table 1).Each cultivar has a different genotype so the growth response shown also varies.Each genotype has differences on genetic and adaptation to the environment so it shows different growth characteristics [11], [12].Plant growth is an event of increasing plant size, which can be measured by increasing the size and height of plant organs, while plant development can be seen by changes in the shape of stem, root and leaf organs, the appearance of flowers and the formation of fruit.The increase in overall plant body size is the result of an increase in the number and size of cells [13].
Chrysanthemum plants grown in vitro on ½ MS + 50 g/l sweet potato media showed significantly higher stem growth compared to other treatments at 7 to 35 days after planting (DAP).Moreover, the media treatment of ½ MS + 50 g/l sweet potato also showed the best plant height at 49 DAP (Table 1).Sweet potatoes are a source of carbohydrates, protein and contain several types of vitamins such as vitamin B, niacin, vitamin A, riboflavin, especially thiamine as much as 0.1 mg/100 g.Thiamine is a vitamin B1 which functions to accelerate cell division in meristem tissue.Apart from that, carbohydrates play an important role as an energy source for plantlet growth [14].Chrysanthemum explants of the Nareswari Agrihort and Suciono Agrihort cultivars showed almost the same shoot emergence time.Although statistically the difference was not significant, planting chrysanthemum explants in vitro on ½ MS + 50 g/l sweet potato media could speed up the time of shoot emergence by up to 24% compared to the control (Figure 1).Likewise, on the number of shoots parameter, Nareswari Agrihort and Suciono Agrihort cultivars produced non-significantly different numbers of shoots.MS media modification treatment also showed no significant difference in the number of shoots produced (Table 2).However, if seen from another point of view, this shows that the addition of organic materials, such as bananas, coconut water and sweet potatoes can increase the efficiency of using MS media by as much as 50% in in vitro propagation of chrysanthemum plants.The Suciono Agrihort cultivar chrysanthemum plants produced significantly more leaves than the Nareswari cultivar at 49 DAP.However, each in vitro culture media modification treatment did not show any significant differences (Table 3).Leaf growth is caused by cell division which produces new cells, as well as cell elongation, or enlargement of the cells themselves.Each plant species has different gene activity so that it produces auxin at different levels [15].Growth is a process of plant life that results in changes in the size of plants that become larger.The increase in overall plant body size is the result of an increase in the number and size of cells [13].Further studies regarding chrysanthemum cultivars still need to be carried out considering that chrysanthemum plants have many potential phenotypes that can be explored.Based on research results, the addition of organic materials could reduce the MS media usage for in vitro propagation of chrysanthemum plants because it showed the plant growth that was no lower than when using full MS media.The use of organic materials especially sweet potatoes has good potential to help chrysanthemum cultivators to provide mass superior planting materials in a short time to meet consumer demand for chrysanthemums.
Conclusion
Based on the research results, Suciono Agrihort was the best cultivar for in vitro propagation of chrysanthemum plants based on plant height and number of leaves, while ½ MS medium + 50 g/l sweet potato was the best modified MS medium based on plant height.The addition of organic materials that had been tested could reduce the MS media usage by as much as 50% in in vitro propagation of chrysanthemum plants.
Figure 1 .
1
Figure 1.Time of shoot emergence on various cultivars (a) and modified MS media (b)
Table 1 .
1
Plant height on various cultivars and modified MS media at 7 -49 days after planting
Treatments7Plant height (cm) at various ages of days after planting 14 21 28 35 4249CultivarsNareswari Agrihort1.462.634.03 b 5.20 b 6.28 b 6.64 b 7.31 bSuciono Agrihort1.723.265.51 a 6.14 a 7.36 a 7.68 a 8.03 aIn vitro mediaMS (control)1.34 b 2.60 b 4.23 b 6.37 b 6.83 b 7.23 ab 7.60 ab½ MS + 50 g/l banana1.40 b 2.32 b 4.51 b 4.97 b 5.82 b 6.38 b 7.04 b½ MS + 50 ml/l coconut water1.49 b 2.74 b 4.12 b 5.50 b 6.55 b 6.99 ab 7.47 b½ MS + 50 g/l sweet potato2.12 a 4.11 a 6.22 a 6.85 a 8.07 a 8.04 a 8.58 a
Note: Values followed by different letters within a column are significantly different according to DMRT α=5%
Table 2 .
2
Number of shoots on various cultivars and modified MS media at 7 -49 days after planting
TreatmentsThe number of shoots at various ages of days after planting 7 14 21 28 35 42 49CultivarsNareswari Agrihort1.061.061.111.141.141.141.14Suciono Agrihort1.001.031.061.101.101.101.10In vitro mediaMS (control)1.111.111.171.171.171.171.17½ MS + 50 g/l banana1.061.061.061.281.391.391.39½ MS + 50 ml/l coconut water0.920.920.920.920.920.920.92½ MS + 50 g/l sweet potato1.001.001.001.001.001.001.00
Table 3 .
3
Number of leaves on various cultivars and modified MS media at 7 -49 days after planting
TreatmentsThe number of leaves at various ages of days after planting 7 14 21 28 35 42 49CultivarsNareswari Agrihort2.894.196.367.719.5010.1011.00 bSuciono Agrihort3.285.477.319.7610.8911.9213.24 aIn vitro mediaMS (control)3.95 a 5.447.458.6410.6111.2212.33½ MS + 50 g/l banana2.44 b 4.337.118.7211.0612.1713.55½ MS + 50 ml/l coconut water2.00 b 4.115.848.979.119.4210.58½ MS + 50 g/l sweet potato3.95 a 5.457.118.6110.0011.2212.00
Note: Values followed by different letters within a column are significantly different according to DMRT α=5%
AcknowledgementThe authors would like to thank Politeknik Negeri Jember, as this study was supported by a research contract to implement the PNBP Funded Research Program Basic Research in 2023.
. A Pratiwi, G B Saputro, N A Dewantari, J. Biol. Trop. 2222022
Badan Pusat, Statistik , Statistik Indonesia 2023. Jakarta: Badan Pusat Statistik. 2023
Cut chrysanthemum. A M Kofranek, Introduction to Floriculture. A Larson, LondonAcademic Press19923rd ed., R.
. Y P B Ziraluo, J. Inov. Penelit. 232021
. A H H Basri, Agro Ekstensia. 1012016
. L Yuliani, J Erwin, Unsur, 20147
. N Impitasari, E Nurcahyani, T T Handayani, Y Yulianty, J. Ilm. Biol. Eksperimen dan Keanekaragaman Hayati. 522019
. S Pendong, W Tilaar, J L Tombuku, S L Tumbel, Maj, Info Sains, 20201
. M S Rahayu, H E Prayogi, 10.29244/agrob.1.4.94-100Bul. Agrohorti. 14Jan. 2014
. D S I Putri, Damanhuri J Produksi Tanam, 20186
. S Subaedah, S Numba, Saida J Agron, Indones. Indonesian J. Agron. 4621692018
. A T Hapsari, S Darmanti, E D Hastuti, Bul. Anat. dan Fisiol. 312018
. S N Meilani, S D Anitasari, F J Zuhro, Florea, 20174
. S Yono, Ananto , 2023
| [
0.06565038114786148,
-0.016332462430000305,
-0.0995868593454361,
-0.11512288451194763,
0.024417147040367126,
0.12547768652439117,
-0.05838165432214737,
0.13071145117282867,
-0.019486941397190094,
0.08475294709205627,
0.08382879942655563,
-0.17616969347000122,
0.062455914914608,
-0.15329298... |
How Do Mothers and Fathers Talk About Parenting to Different Audiences? Audience Effects and Stereotypes: An Analysis of r/Daddit, r/Mommit, and r/Parenting Using Topic Modelling
25 Feb 2022
Melody Sepahpour-Fard melody.sepahpourfard@ul.ie
Michael Quayle mike.quayle@ul.ie
Department of Mathematics and Statistics
SFI Centre for Research Training in Foundations of Data Science
University of Limerick Castletroy
LimerickIreland
Centre for Social Issues Research and Department of Psychology
University of Limerick Castletroy
LimerickIreland
Department of Psychology
School of Applied Human Sciences
University of KwaZulu-Natal Durban
KwaZulu-Natal
South Africa
How Do Mothers and Fathers Talk About Parenting to Different Audiences? Audience Effects and Stereotypes: An Analysis of r/Daddit, r/Mommit, and r/Parenting Using Topic Modelling
25 Feb 202279B2CB6181F15D374932FF793761389010.1145/3485447.3512138arXiv:2202.12962v1[cs.CY]Redditparentinggender stereotypessocial identity performanceaudienceLDA topic modellingnatural language processingcomputational social sciencesocial psychology
While major strides have been made towards gender equality in public life, serious inequality remains in the domestic sphere, especially around parenting.The present study analyses discussions about parenting on Reddit (i.e., a content aggregation website) to explore audience effects and gender stereotypes.It suggests a novel method to study topical variation in individuals' language when interacting with different audiences.Comments posted in 2020 were collected from three parenting subreddits (i.e., topical communities), described as being for fathers (r/Daddit), mothers (r/Mommit), and all parents (r/Parenting).Users posting on r/Parenting and r/Daddit or on r/Parenting and r/Mommit were assumed to identify as fathers or mothers, respectively, allowing gender comparison.Users' comments on r/Parenting (to a mixed-gender audience) were compared with their comments to single-gender audiences on r/Daddit or r/Mommit using Latent Dirichlet Allocation (LDA) topic modelling.Results showed that the most discussed topic among parents is about education and family advice, a topic mainly discussed in the mixed-gender subreddit and more by fathers than mothers.The topic model also indicated that, when it comes to the basic needs of children (sleep, food, and medical care), mothers seemed to be more concerned regardless of the audience.In contrast, topics such as birth and pregnancy announcements and physical appearance were more discussed by fathers in the father-centric subreddit.Overall, findings seem to show that mothers are generally more concerned about the practical sides of parenting while fathers' expressed concerns are more contextual: with other fathers, there seems to be a desire to show their fatherhood and be recognized for it while they discuss education with mothers.These results demonstrate Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page.Copyrights for third-party components of this work must be honored.For all other uses, contact the owner/author(s).
INTRODUCTION
The present study explores how mothers and fathers express concerns related to parenting on Reddit.Using topic modelling, more than a hundred thousand comments published on Reddit in 2020 were analysed to describe parenting talk.Parents' comments on three subreddits related to parenting-two single-gender (r/Daddit and r/Mommit) and one mixed-gender (r/Parenting)-were analysed using topic modelling to see whether speakers are sensitive to the audience's gender identity and if the content of parents' talks reflects gender stereotypes.Parenting is an important domain of study because women frequently face a double burden of working full-time outside the house but also carrying the primary responsibility for caring and home-making [7].Consequently, women often lower their professional ambitions to satisfy the needs at home and, therefore, fragilise their financial independence [25].Equality in the public sphere first requires equality at home.Why are women still preferentially perceived to be primary caregivers [35]?Generalisations about the shared attributes of social groups [17], or stereotypes, constitute an essential factor in assigning such duties to women [12].From simple beliefs, stereotypes become concrete in shaping individuals' behaviour once they are widely accepted and become injunctive norms for a social group to act in a specific way [12].
The parenting domain has especially profoundly rooted stereotypes about how mothers and fathers should behave.For this reason, the present study will focus on discourses related to parenting behaviours using congruency with gender stereotypes as a framework of understanding.In the literature review, we will first define stereotypes related to gender and show how they can create expectations for mothers and fathers regarding parenting behaviours.Secondly, we will integrate audience as a factor that can make a social category salient and facilitate identity-relevant behaviour.For this second part, we will define social categorisation, how it has been theorised, and its relation with social identity performance [18] in front of an audience.Finally, we will describe the online context of Reddit, the selected subreddits, and related previous research.
LITERATURE REVIEW 2.1 Gender Stereotypes and Parenting
Gender stereotypes assign specific attributes, characteristics, and responsibilities, and these become standards to which individuals should conform to be positively judged by society [34].Generally, women are assigned "communal" characteristics such as selflessness and care, and men "agentic" characteristics such as mastery and assertiveness [11].These gender stereotypes are associated with the domains of family for women and work for men, and thereby culturally facilitate home-making for women and outside work for men [12].Put differently, these gendered associations can undermine women's professional ambitions in favour of their domestic identity.For instance, women are more likely than men to pass up promotions, take less demanding jobs, switch to part-time jobs, and drop out of the labour force once they become parents [25].The reverse is true for fathers, who are still considered secondary parents [35], even if they aspire to be more involved in caring [8].
Social Categorisation and Audience Related
to Stereotypical Behaviours 2.2.1 Social Categorisation and its Theorisation.Categorisation -the assignment of people to discrete categories based on fuzzy criteria -is a fundamental psychological process [29,30], resulting in perceptions of groups characterised by sets of defining characteristics, or stereotypes [12].Social categorisation is, therefore, a precondition to the formation of stereotypes.As described in the Social Identity Theory [29,30], when people identify with a social group, they think, feel, and act as group members [30], and appropriate behaviour is defined by the group's self-stereotypes and norms [30].The Self-Categorization Theory [32] adds a dynamic aspect, noting that people can shift across social identities as they move across social contexts.When individuals define themselves with a social category in a specific context, they tend to conform to the norms characterising their social identity in that context [31]."Mother", "father", and "parent" are social categories individuals can identify with.They can become salient in a given context and prompt individuals towards more identity-relevant (i.e., stereotypical) behaviours.Thus, the audience is an important trigger of the salience of social categories.
2.2.2 Audience and Self-Categorisation.The social identity performance framework [18] describes the impact of an audience on the salience of a social category: available and visible audiences affect the expression of social identity, and the audience's feedback affects the nature of the social identity itself.Actors are particularly likely to enact group norms when they define themselves as group members and think they are visible to an audience [18].According to this framework, the people likely to conform to group norms most enthusiastically are those with uncertain membership [6] who might "overconform" with an identity consolidation purpose, i.e., enacting even more intensely the group's norms to make their commitment clear [18].
There is evidence that the audience and its expectations regarding gender roles can shape individuals' behaviour [19,23,24].For example, in the context of education, although both men and women can make stereotypical choices, the influence of gender stereotypes in a mixed-gender environment seems to be stronger for girls: girls tend to act more gender stereotypically in mixed-sex schools than in single-sex schools, whereas boys tend to act more gender stereotypically in single-sex schools [13].These findings encourage research exploring behavioural differences between single-and mixed-gender audiences and how behaviours in these environments can reflect gender stereotypes.
Reddit as a Platform to Study Gender
Stereotypes and Audience Effects Related to Parenting We will focus on these subreddits to explore the extent to which parenting talk reflects common gender stereotypes, but also how it is sensitive to the audience, as we describe in more detail in the method section below.
Prior
Studies on Parenting Subreddits.At least two published studies have explored the expression of parenthood on Reddit, one using an ethnographic approach [14] and the other using a computational approach [1].
Feldman's study [14] applied qualitative grounded theory to posts on r/Mommit and r/Daddit to explore how Reddit users negotiate gendered parenting ideologies.They found that Reddit users reproduce the stereotypical gender roles painting the mother as the primary caregiver and the father as the secondary caregiver on r/Daddit and r/Mommit.For instance, on r/Mommit, mothers talk about a dyadic mother-child relationship while fathers on r/Daddit talk about a triadic father-mother-child relationship.Furthermore, whereas good fathering is defined as being present and spending time with their child (shown through pictures of their child), good mothering is defined as positively shaping and impacting their child.Feldman [14] describes fathers' concerns to be centred around whether they care for their child and mothers' to be about how to care for their child.While Feldman's research [14] provides essential insight, the method is intensive and only allowed the analysis of one month of data.With the number of published posts on Reddit being substantial, quantitative text analysis methods such as topic modelling may allow more comprehensive analysis.Furthermore, as this work is about expressed concerns in interaction and knowing that single-gender audiences differ from mixed-gender audiences [13,21], it is interesting to see how Reddit parents interact on a mixed-gender subreddit.The latter can tell us whether the users differ regardless of the audience or if their expressed concerns relate to the audience they interact with.
A study by Ammari et al. [1] used topic modelling to describe the most discussed topics on r/Mommit, r/Daddit, and r/Parenting.They collected the comments published on these subreddits between 2008 and 2016, from which they identified 47 topics, summarised in eight main areas (as one area is missing in their article, we consider the seven others): (a) Birth, milestones, and transition to teen years; (b) Discipline or abuse; (c) Judgment; (d) Play and competition; (e) Purchase suggestions; (f) Faith and family; (g) Posting norms.r/Parenting users talked more about discipline and teen talk.r/Mommit users discussed the most topics such as Sleep training, breastfeeding, milestones, child weight gain, pregnancy recovery, and housework.On r/Daddit, the most frequent topics were congratulations, Neonatal Intensive Care Unit (NICU) experience, legal questions for custody battles, and Halloween costumes.Both r/Daddit and r/Mommit users talked about posting on social media, preparing food, circumcision, vaccination, and naming children.
Although Ammari et al. [1] present interesting results, there are significant limitations that we will tackle in the present research.In terms of design, although they acknowledge that r/Mommit and r/Daddit are mother-centric and father-centric, respectively, they do not emphasise their particularity of being single-gender subreddits and r/Parenting being a mixed-gender subreddit, and therefore miss any possible contextual audience effects.However, research showed the effect of the audience gender at school [13], online [23], and offline [19].Therefore, the gender diversity of an audience should be considered and studied to include potential variations due to it.
Present Study
The present research extends previous research to integrate the study of audience effects, a quantitative text analysis method using topic modelling, and a precise and transparent process of qualitative inference.Regarding the audience effects, little research on the differential impact of single-and mixed-gender audiences has been done, especially regarding parenting.To analyse the variation linked to the audience, participants who have interacted with both types of audiences are selected.This design allows the study of gender differences in relation to the context in which they appear.More specifically, this study explores how mothers and fathers discuss topics related to parenting with different audiences through the analysis of comments published in 2020 in Reddit's popular subreddits regarding parenting: r/Daddit, r/Mommit, and r/Parenting.These three subreddits mainly differ in the audience they claim to gather, either a single-gender audience (r/Daddit and r/Mommit) or a mixed-gender audience (r/Parenting).The difference in audience is assumed from the descriptions of the subreddits themselves: r/Daddit is for fathers, r/Mommit is for mothers, r/Parenting is for parents.First, we will identify mothers (users who have posted on both r/Mommit and r/Parenting but not r/Daddit) and fathers (users who have posted on both r/Daddit and r/Parenting but not r/Mommit).Then, topic modelling is used to describe parenting talk and see if the change in expressed concerns corresponds with the change of audience and if there are gender differences in relation to gender stereotypes.
METHOD 3.1 Dataset
Reddit comments were collected using Pushshift's API1 [2], a social media data collection, analysis, and archiving platform updated in real-time.Two sets of comments were collected: (a) all the comments published in 2020 on r/Daddit and r/Parenting by authors who published on both and (b) all the comments published in 2020 on r/Mommit and r/Parenting by authors who published on both.The raw dataset contains 194,497 comments published by 8,361 unique Reddit users.
Topic Modelling
Topic modelling is a computer-based method developed in the field of Natural Language Processing.Given a vast amount of text data, the machine learning algorithm identifies underlying topics in the corpus.Because it is automatic, the method allows very consistent detection of topics for large datasets, whereas manual qualitative analysis, which relies on human coders, can be inconsistent [9] and very time-consuming.To find suitable topics, topic modelling involves counting words and grouping similar word patterns.However, topics based on word co-occurrence in documents rather than conceptual similarity can result in the algorithm's output showing hardly interpretable topics.
Latent Dirichlet Allocation [5] topic model is one of the most well-known topic modelling techniques.It is a generative probabilistic model of a corpus.The probabilistic model generates data by identifying how the input data was created word by word.The generated data is based on two probability distributions associated with two hyperparameters: (a) the probability q, which captures how likely it is for each topic to represent a document.The hyperparameter , the topic prior, is associated with the probability q and controls how many topics we expect each document to have.The higher the value , the more topics each document will be associated with.(b) the probability z, which captures how likely it is for each word to represent each topic.The hyperparameter , the word prior, is associated with the probability z and controls how topic-specific we want each word to be.The higher the value , the greater the number of topics each word will be associated with [16].To test and evaluate different topic models efficiently, a coherence measure ( V ) is used to assess the human interpretability of the model [27].The interpretation and labelling of topics are qualitatively carried out using the keywords defining each topic in the output of the topic model.Once the topics are identified, we can then describe each of our documents as a distribution of those topics and find the dominant topic in each document [16].
Preprocessing
To be coherent with our assumption that r/Mommit posters are most likely to identify as women and r/Daddit posters as men, we removed 502 authors who posted both on r/Mommit and r/Daddit as they make the comparison between these two groups less meaningful.They potentially correspond to mothers posting on r/Daddit and fathers posting on r/Mommit.Thirty-six obvious bots, identified because their pseudonyms contained the word "bot", were removed.Deleted comments, comments written by the Auto Moderator, and stop words (i.e., the words that occur in abundance and provide only little to no information about the content of textual data) were removed too.Some authors were removed because of empty comments (e.g., single-word comments such as "OK" became empty because of the removed stop words).We kept only the authors for whom the dataset still contained at least one post on a single-gender subreddit and one on the mixed-gender subreddit.In this way, we were able to analyse the effects of a change of audience for the same users.This dataset represents 145,771 comments posted by 7,791 authors (comments per author: M = 18.71,SD = 62.24,Mdn = 7.00, Min = 2.00, Max = 3769.00).Of these, users who have posted on both r/Daddit and r/Parenting in 2020 represent 2,967 users, with 16,328 comments on r/Daddit and 27,263 comments on r/Parenting; users who have posted on both r/Mommit and r/Parenting in 2020 represent 4,824 users, with 23,977 comments on r/Mommit and 78,203 comments on r/Parenting.For clarity regarding the explanation of results, we assumed that users posting on r/Daddit or r/Mommit (and not on both) identify as "fathers" and "mothers", respectively.We made the text lower-case and removed punctuation, special characters, and hyperlinks.This dataset was kept for the second part of the study, which will use the topic model to attribute a relative frequency of topics in each comment.
The data was lemmatised (i.e., the different inflected forms of words were replaced by their normalised form) using NLTK [4], a module for Natural Language Processing in Python [33] and WordNet [15,20], a lexical database for the English language.The data was tokenised, and the list of English stop words [22] was removed.Additionally, after a first model inference, we added these words to the list of stop words [28] to increase interpretability: "time", "hair", "day", "month", "week", "hour", "year", "minute", "idea", "adult", "age", "comment", "people", "person", "man", "sure".The Gensim module [26] was used in Python to create a bigram model for improving the quality of the inferred topics [36].A bigram model uses a sliding window of two terms to examine the text (each combination of two adjacent words is considered) and find combinations of two words which should be analysed as one term because one unique concept spans the two words, e.g., "mental health" [16].Using Gensim [26], a dictionary giving each term an integer identification was created, and doc2bow (i.e., document to bag-of-words) function was used to convert documents into a bag-of-words format.A document in bag-of-words format means that each document is represented by the number of unique terms it contains and the number of times each of these terms occur.To reach a more interpretable topic model, we tried to keep only nouns and nouns and verbs using NLTK's [4] part-of-speech tagger (i.e., a function that assigns each word a grammatical descriptor).After calculating the coherence scores for models ranging from two to 50 topics, we decided to keep the model with only nouns, resulting in higher coherence scores and greater human interpretability.The corpus used for topic modelling contained 136,256 documents (i.e., comments) and a vocabulary of 9,969 unique tokens.
Data Analysis
LDA topic modelling was run2 on the corpus using Gensim module [26] in Python [33].Coherence scores ( V ) were used to define the optimal number of topics. V was at its highest value when the model had 12 topics.Therefore, we pursued the analysis with 12 topics.To set the hyperparameters and , we ran multiple models for different values of hyperparameters and then selected the settings that resulted in the best V .The highest coherence score was V = .60when = .01and = .61.Chunk size controls how many documents are processed at a time in the training algorithm, passes control how often we train the model on the entire corpus, and iterations control how often we repeat a particular loop over each document [26].We set ℎ = 5000, = 40, and = 1000 and the topic model reached a coherence score V = .62.
Once we have established the topic model, we can represent each comment as a distribution of topics.The keywords defining a topic were compared with the words in the comment, and from the similarity between these two sets of words, we could calculate the relative frequency of topics in each comment 3 .Because we used a very low alpha parameter ( = 0.01), the comments were represented only by a few topics, making the comparison between comments easier, especially for comparing groups of comments.From these relative frequencies, the average scores of topics were calculated for comments aggregated by gender and audience: mothers on r/Mommit, mothers on r/Parenting, fathers on r/Daddit, and fathers on r/Parenting.
RESULTS
Topics
The resulting topic model included 12 topics: Thank you/Appreciation, Medical care, Education/Family advice, Furniture/Design, Birth/Pregnancy, Change/Potty training, Physical appearance/Picture, Work/Raise children, Food, Leisure activities, School/Teaching, and Sleep training.To label each topic, we used the list of keywords and the comments which scored the highest on the topics (see Appendix).We will give examples of keywords used to label each topic so the reader can understand the inference process:
• Thank you/Appreciation: "thank", "thanks", or "advice" indicate that this topic seems to be related to parents responding to advisory or helpful posts and thanking other users.• Medical care: "doctor", "issue", or "health" indicate that this topic seems to be related to parents sharing experiences about their health and their children's.• Education/Family advice: "situation", "family", or "problem" indicate that this topic seems to be related to parents sharing their advice about how to handle a situation.• Furniture/Design: "room", "floor", or "space" indicate that this topic seems to be related to parents discussing physical arrangements, e.g., in the house.• Birth/Pregnancy: "life", "pregnancy", or "birth" indicate that this topic seems to be related to parents reacting and congratulating other parents for birth and pregnancy announcements.• Change/Potty training: "diaper", "potty", or "toilet" indicate that this topic seems to be related to parents sharing experiences about their children's diaper changes, stools, and toilet training.• Physical appearance/Picture: "look", "face", or "picture" indicate that this topic seems to be related to parents reacting to pictures and physically describing their children.• Work/Raise children: "home", "family", or "work" indicate that this topic seems to be related to parents sharing experiences about finding a balance between work and raising children.• Food: "food", "meal", or "snack" indicate that this topic seems to be related to parents sharing recipes and experiences about their children eating.• Leisure activities: "book", "play", or "fun" indicate that this topic seems to be related to parents sharing about their free-time activities.• School/Teaching: "school", "teacher", or "class" indicate that this topic seems to be related to parents sharing about academic education and teaching practices.• Sleep training: "night", "sleep", or "bedtime" indicate that this topic seems to be related to parents sharing about sleep training.Regarding Change/Potty training, there was a clear distinction between the mixed-gender subreddit and the singlegender ones; the topic was more discussed on the latter.However, although the difference seemed to be due to the audience, mothers on r/Mommit discussed Change/Potty training more than fathers on r/Daddit and mothers on r/Parenting more than fathers on r/Parenting.Among mothers, a similar interaction between gender and audience was visible in the other topics related to basic needs as mothers always discussed them more on the single-gender subreddit r/Mommit.
Relative frequency of topics
Announcements and introductions were an important topic for fathers in the single-gender subreddit.Fathers on r/Daddit had the highest scores on the topics Birth/Pregnancy, Thank you/Appreciation, and Physical appearance/Picture.Among these topics, the topic Birth/Pregnancy, which includes birth announcements and congratulating comments, showed the greatest difference between fathers' comments on the single-gender subreddit r/Daddit and other comments.
Education and leisure were especially discussed by mothers and fathers on r/Parenting.In other words, the topics Education/Family advice, Work/Raise children, Leisure activities, and School/Teaching were more discussed with the mixed-gender audience.These topics seemed to represent norms regarding the expected topics Reddit users should discuss on r/Parenting.Regarding gender differences, mothers and fathers discussed Work/Raise children, Leisure activities, and School/Teaching similarly, whereas Education/Family advice was discussed more by fathers than mothers.Education/Family advice was also the most discussed topic overall.
Physical arrangements were more discussed in the single-gender subreddits than in the mixed-gender.
Findings showed gender differences and differences between single and mixed-gender subreddits, but, for some results, the subreddits' norms and their potential influence should be considered.Our sample included four groups (i.e., fathers on r/Daddit, fathers on r/Parenting, mothers on r/Mommit, mothers on r/Parenting) but only three subreddits.This fact was, to some extent, reflected in the results.Across all topics, there seemed to be more similarities between mothers and fathers on r/Parenting than between other groups.For instance, there appears to be an important overlap between mothers and fathers on r/Parenting for the topics Thank you/Appreciation, Birth/Pregnancy, Change/Potty training, Physical appearance/Picture, Leisure activities, and School/Teaching.
DISCUSSION
The findings of the study illustrate the concerns expressed by mothers and fathers on Reddit.Leaning on the social identity performance framework that shows the importance of an audience for social identity salience [18], the study aimed to explore gender differences in relation to an audience.Three popular subreddits related to parenting were selected as they differ in the gender and audience they target and attract: r/Daddit is a father-centric subreddit with an overtly single-gender audience, r/Mommit is a mother-centric subreddit with an overtly singlegender audience, and r/Parenting is a parent-centric subreddit with a mixed-gender audience.Parents' posts across these subreddits were analysed using LDA topic modelling, which captured 12 topics summarised into four areas: Basic needs (Food, Sleep training, Medical care, Change/Potty training), Announcements and introductions (Birth/Pregnancy, Thank you/Appreciation, Physical appearance/Picture), Education and leisure (Education/Family advice, Work/Raise children, School/Teaching, Leisure activities), and Physical arrangements (Furniture/Design).These 12 topics were then used to compare parents in terms of gender and audience, resulting in three main findings.First, basic needs were more discussed by mothers regardless of the audience.Second, announcements and introductions were more discussed by fathers with a single-gender audience.Third, education and leisure were discussed by both mothers and fathers, especially with a mixed-gender audience.We will put these results into perspective, comparing them with theories and previous studies in the following paragraphs.
Firstly, findings showed gender differences between mothers and fathers.The latter appeared in three topics, with mothers always discussing them the most: Food, Sleep training, and Medical care.Sleeping, eating and health are probably the most important topics related to the child's survival; they represent their basic needs.By being the users who discuss the most these topics, mothers position themselves (and are positioned) as the primary caregiver with communal characteristics [11,12].These findings are coherent with the previous studies of Ammari et al. [1] and Feldman [14], conducted in the same context.Ammari et al. 's [1] found that r/Mommit users are the ones discussing the most topics related to sleep training, breastfeeding, milestones, child weight gain, and pregnancy recovery.Feldman's analysis [14] showed mothers as more concerned about how to care for their child, i.e., child-rearing's practical and concrete sides.Therefore, gender differences, as predicted by previous research, were reflected in the present study, especially for mothers expressing concerns about the child's basic needs, and this was the case regardless of audience and context for the topics Food, Sleep training, and Medical care.
Secondly, findings partially demonstrated an audience effect as described by previous research.Research on the Self-Categorization Theory [32] and the social identity performance [18] has shown how the salience of a social category and the audience result in individuals behaving in coherence with the group norms.Additionally, as demonstrated in the comparison between mixed and singlesex schools, the mixed-gender environment pushed girls towards more stereotypical behaviours than the single-gender environment, whereas the opposite happened for boys [13].In the present study, it seems like fathers did act more gender stereotypically with a singlegender audience, but for mothers, the findings are more nuanced and depend on the topic.With single-gender audiences, both mothers and fathers announced pregnancies and births and introduced their children.However, fathers, in terms of relative frequency, scored higher on these topics than mothers.The latter confirms Ammari et al.'s [1] findings where one of the most discussed topics in r/Daddit was congratulations.The results are also coherent with Feldman's [14] results: r/Daddit users talking about whether they care for their child through posting pictures, announcing pregnancies and births, and reacting to these announcements.In the present work, the topics Thank you/Appreciation, Birth/Pregnancy, and Physical appearance/Picture touch on an abstract, superficial aspect of parenting, which is more about the recognition of a "parent" identity (the whether [14]) than the actual parenting function (the how [14]).This quest for recognition and the emphasis on physical appearance and celebration create an almost trophy-like image of the child and can be associated with gender stereotypes related to the expectation of performance for men [12] and confirm the increase of gender-stereotypical behaviours for fathers in single-gender environments [13].The results are more nuanced for mothers.On the one hand, mothers expressed less stereotypical concerns with a single-gender audience, as they talked more about topics related to recognition and celebration.On the other hand, mothers also expressed more stereotypical concerns with a singlegender audience.Indeed, mothers expressed concerns regarding the child's basic needs (Sleep training, Food, and Medical care) preferentially with a single-gender audience.Therefore, although the audience seemed to have an expected effect on fathers with announcements and introductions, the findings were unexpected for mothers who discussed more the stereotypical area of basic needs with a single-gender audience than with a mixed-gender audience.
Thirdly, under pseudonyms, fathers on r/Parenting interact with other fathers and with mothers, from whom they may wish to gain recognition as legitimate parents.The salience of the "parent" social category and the threat to be rejected because they are expected to be secondary parents [35] can push them towards "overconformism" [18], making them behave more as prototypical parents than mothers.The topic Education/Family advice seems to reflect this phenomenon.This topic is discussed approximately twice as much with the mixed-gender audience than with the single-gender audiences by both mothers and fathers.However, although both mothers and fathers posted a lot about this topic, the difference between mothers and fathers on r/Parenting is the greatest among all topics.The latter might reflect fathers' overconformity in this context.As an alternative explanation, we can also question the particularity of the topic Education/Family advice.The comments which scored the highest on this topic reflect an agentic aspect of parenting [11] where parents give advice about what they would do and what other parents should do in different situations.This agency seems to reflect the position of authority or control fathers are associated with [3] and be, thus, a stereotypical behaviour associated with men.Therefore, fathers talking predominantly about education and giving family advice with the mixed-gender audience is difficult to interpret as it can be due to overconformism but also to the agency associated with advising others.
Implications
The present work explored how expressed concerns about parenting can inform us of gender stereotypes and audience.Additionally, this study introduced a novel method to explore, in parallel, differences between two groups (i.e., mothers and fathers) and individuals' contextual differences (i.e., with a single-gender audience or a mixedgender audience).This method allowed the capture of gender and audience differences regarding parenting talk on Reddit.With this method, mothers and fathers' behaviours were analysed when separated in single-gender audiences and gathered in a mixed-gender audience.Previously, in a study gathering r/Daddit, r/Mommit, and r/Parenting, Ammari et al. 's [1] had included r/Parenting comments in their dataset without acknowledging the potential impact induced by the change in audience.Leaning on the social identity performance framework [18] and Favara's study [13] about singlesex schools, the inclusion of r/Parenting was made meaningful and allowed the exploration of audience and gender in interaction.In the following two paragraphs, we will expand on the scientific contribution of the present research and its potential societal impact.The findings contributed to two research areas: the expression of concerns related to gender stereotypes and the relationship between audience change and behavioural change.
The results presented here enrich the literature about the evolution of gender roles by providing a picture of parents' concerns expressed on Reddit in 2020.The topics and their distribution across users' comments showed a gendered division of parenting in parents' discourse.Additionally, the research supported the hypothesis of a gender-differentiated impact of mixed and non-mixed audiences on individuals.Research on this differential impact has been mainly studied in the education context [13] despite potentially touching every sphere of society.Therefore, we broadened the research on single-gender and mixed-gender environments by applying this perspective in the social media context in relation to parenting.To suggest a more robust methodology, we included the framework of social identity performance [18].This way, we focused on individuals' behavioural changes related to an audience as a social identity activator.The integration of the two frameworks of understanding, i.e., gender stereotypes and audience, allowed for a holistic approach to the analysis of expressions online.
Regarding the societal impact of this research, the findings echoed the unequal division of labour in the offline world.On the one hand, mothers expressed concerns about the practical aspects of child-rearing, reflecting the characteristics associated with motherhood.On the other hand, fathers seem to be more concerned about expressing their fatherhood and showing that they care for their child.Although this study does not establish any causal relationship between stereotypes and gender differences on Reddit and only describes their overlap, we can still question the potential effect of stereotypes.Stereotypes can profoundly impact behaviours, resulting in group-based expectations that restrain individuals from behaving in a non-expected manner.In this study, the overlap between parenting talk and gender stereotypes shows how stereotypes constitute a powerful framework for looking at and understanding interactions regarding parenting.
Limitations
A non-representative sample.
The sample does not include all parents who published on the three subreddits in 2020.We have only selected mothers and fathers who have published comments on both a single-gender subreddit (r/Mommit or r/Daddit) and a mixed-gender subreddit (r/Parenting).This participants' selection strategy might have biased the results.Indeed, parents may choose to post comments on two different subreddits about parenting precisely because they want to express different concerns to different audiences.Therefore, our results might not apply to parents who published on only one of the subreddit.For example, r/Daddit users who publish exclusively on this subreddit might express all their concerns (including all the topics found in this study) to that audience.Thus, the choice of reducing the sample to only the users who published on at least two parenting subreddits may have biased the findings.
The sample also has an impact on the generalisability of the study.Reddit data is not representative: Reddit parenting communities do not represent all social media parenting communities, let alone offline parenting.For instance, Reddit is popular in Englishspeaking countries.Even if there are other languages on Reddit, the subreddits we chose gathered almost exclusively comments written in English.Therefore, the work cannot be generalised to all cultures.Moreover, fathers writing on r/Daddit and sharing experiences about fatherhood may be a population that is already more concerned about parenting than the average father.Therefore, the latter can result in fewer differences between mothers and fathers on Reddit (in these subreddits) than there is offline.Thus, the particularity of Reddit and its users should be considered to prevent overgeneralisation.5.2.2 Analytic judgement.We note that the advanced techniques of machine learning and topic modelling do not erase interpretation bias.Once the topic model has been created, the researcher has several sets of words from which they want to make sense.Although some topics are almost obvious, others are more subject to interpretation, and this judgement is qualitative.
Future Research
The present research has shown how parenting talk reflects gender stereotypes and how the audience can shape the expression of concerns.To support and solidify the findings about the audience effect, the gendered expression of concerns and an actual unequal division of labour between parents, this exploratory and observational study can be complemented by an online experiment and a survey.With an online experiment, we can effectively anonymise participants and make them interact online with other participants about parenting, either with a single-gender audience or with a mixed-gender audience.The gender identifiability, the name of the communities, and the number of mothers and fathers can be manipulated.With a survey, it will be possible to explore the relationship between online and offline behaviours related to parenting.Finally, for further investigation, we would like to question the use of gender as binary in this study and encourage future research to consider other possible definitions of gender and parenting, which can be different from the simple spectrum of motherhood and fatherhood.
CONCLUSION
In the present investigation, we studied parenting talk on Reddit to explore how it reflects gender stereotypes and is sensitive to the audience.Findings indicated that, first, mothers posted more about children's basic needs, regardless of the audience, reflecting the communal characteristics stereotypically associated with women.Secondly, fathers posted more than mothers to announce pregnancies and births and introduce their child, especially to a single-gender audience, showing a more superficial aspect of parenting focused on the social recognition of the "father" identity.Finally, among Reddit parents, discussing education and giving advice were mostly expressed to a mixed-gender audience and more by fathers than mothers, reflecting either the agentic characteristics associated with masculinity or overconformism.The study of audience and gender stereotyping in parenting talk gives an important window into the construction of gender identity in private contexts, which are usually out of view.
Although no link can be directly drawn between these findings and offline behaviours, the echo of gender stereotypes in these online interactions questions the impact of stereotypes in the real world.When mothers decide to behave in a stereotype-based expected manner, they usually have to fragilise their careers through less demanding or part-time jobs.These stereotypes are consequential.Child-rearing not being a paid occupation, instantiating a stereotypically appropriate parenting identity imposes a professional opportunity-cost for women: if women are expected to be primary caregivers at home with their children, men are expected to be outside and contributing to society's organisation.
A TOPICS' LABELS, KEYWORDS, AND HIGH-SCORING COMMENTS B SCORES OF THE GROUPS FOR EACH
TOPIC (COMPLEMENT TO FIGURE 1) "thank", "word", "thanks", "toddler", "sound", "advice", "today", "moment", "hug", "mama" "Thank you!I appreciate your insight and you made good points especially on reversing the words I'm using too:) I like it.Thank you and I really appreciate it."
Medical care "doctor", "issue", "hospital", "formula", "anxiety", "pain", "risk", "depression", "health", "weight" "I have the Copper.I can't do the hormonal ones,not even the minipill.Severe Migraines and doctor feared a higher chance of clots.I've had spotting between periods, but only 2 periods in 14mos.They are very painful.I should note, I didn't find childbirth painful and didn't need pain meds afterwards so I'm not that sensitive to pain." Education/Family advice "situation", "life", "family", "relationship", "problem", "issue", "need", "behavior", "choice", "question" "If I were you, I would call CPS on your husband.I called CPS on my ex while we were still together.He needs tough boundaries and consequences for his choices.You need to protect your children.CPS can provide you with resources to help, and can provide him with resources if he chooses to seek help.Honestly, unless he stops drinking your relationship is over anyways.Set yourself up to be the custodial parent by doing the right things to protect your kids well-being." Furniture/Design "room", "toy", "floor", "door", "clothes", "house", "head", "bathroom", "foot", "space" "Or, stand on a rug,l and draw an outline of yourfeet.Cut them out and duck tape them to your feet.Plus, you never need to buy carpets for your house" Birth/Pregnancy "life", "friend", "love", "partner", "pregnancy", "family", "heart", "birth", "care", "sorry" "Congrats dad!I'm pretty convinced that when babies come out this big they're a lot happier and easier than the littler ones, so I hope that's true for you!"
Change/Potty training "diaper", "post", "body", "hand", "sex", "potty", "poop", "toilet", "arm", "grandma" "I've been changing her constantly.I typically cloth diaper but I have her in honest co diapers and I'm changing these things 2-3 times an hour!" Physical appearance/Picture "dog", "look", "face", "eye", "picture", "cat", "memory", "stranger", "color", "cousin" "My son is 6 months old and he has long eye lashes like in Incredibles coz he looks just like that"
Work/Raise children "home", "family", "work", "house", "car", "job", "money", "friend", "seat", "birthday" "Raising a kid takes a village.Give yourself a break on the weekends or after work if you can.Go for a walk before you pick him up, and get some help so you can have some time.Everyone needs personal time." Food "food", "water", "meal", "milk", "snack", "dinner", "bottle", "cup", "lunch", "eat" "One day I was in the kitchen cooking dinner and I turned my back for 1 second.I turn back and my son had nearly eaten a full clove of garlic like it was a piece of candy.Kids are crazy lol" Leisure activities "book", "game", "play", "attention", "activity", "phone", "tv", "video", "fun", "stuff" "Indeed, board games gets them really excited :) Pick the games that is more about the adventure / fun than on the winning / losing, so that the focus is not so much on that "end" part.Thanks for the great suggestions :)" School/Teaching "school", "teacher", "class", "daycare", "home", "work", "language", "group", "college", "therapy" "I've heard that teaching multiple languages might delay your child's spoken language a little bit compared to just teaching them one language but it's only temporary and the pay off is they end up fluent in more than one language."
Sleep training "night", "bed", "sleep", "morning", "room", "nap", "bedtime", "crib", "work", "schedule"
"I am definitely a morning person!And I struggle to get back to sleep, too.I just like very peaceful, easy mornings.My daughter (who has always been my champ sleeper) takes after me.My son was the baby that woke up every 2h on.the.dot.until I finally had it in me to sleep train after he turned 1.He wakes up ready to charge and tends to be my morning mayhem instigator, despite his efforts to not."
Figure 1
1
Figure1shows topics' scores (i.e., the average relative frequency of topics in comments) for the different groups (i.e., fathers on r/Daddit,
Figure 1 :
1
Figure 1: Scores of mothers and fathers' comments on the twelve topics We will describe the results and analyse the topics summarised into four areas of concern: Basic needs (Food, Sleep training, Medical care, Change/Potty training), Announcements and introductions (Birth/Pregnancy, Thank you/Appreciation, Physical appearance/Picture), Education and leisure (Education/Family advice, Work/Raise children, School/Teaching, Leisure activities), and Physical arrangements (Furniture/Design).The following four paragraphs will develop each of these areas.Basic needs were more discussed by mothers.Except for Change/Potty training, mothers discussed more than fathers the topics related to children's basic needs, regardless of the audience.Mothers (on r/Mommit and r/Parenting) discussed more the topics Sleep training, Food, and Medical care than fathers (on r/Daddit and r/Parenting).Regarding Change/Potty training, there was a clear distinction between the mixed-gender subreddit and the singlegender ones; the topic was more discussed on the latter.However, although the difference seemed to be due to the audience, mothers on r/Mommit discussed Change/Potty training more than fathers on r/Daddit and mothers on r/Parenting more than fathers on r/Parenting.Among mothers, a similar interaction between gender and audience was visible in the other topics related to basic needs as mothers always discussed them more on the single-gender subreddit r/Mommit.Announcements and introductions were an important topic for fathers in the single-gender subreddit.Fathers on r/Daddit had the highest scores on the topics Birth/Pregnancy, Thank
Table 1 :
1
Topics' labels, keywords, and high-scoring comments
LabelKeywordsHigh-scoring commentsThankyou/appreciation
Table 2 :
2
Scores of the groups for each topic (complement to Figure1)
TopicsFathers/Parenting Fathers/Daddit Mothers/Mommit Mothers/ParentingThank you/appreciation.104.121.114.101Medical care.050.054.078.062Education/Family advice.253.118.106.208Furniture/Design.055.073.079.063Birth/Pregnancy.100.159.120.101Change/Potty Training.045.066.074.048Physical appearance/Picture.053.094.079.048Work/Raise children.078.069.072.082Food.039.042.068.051Leisure activities.077.066.060.075School/Teaching.058.034.035.061Sleep training.069.075.092.083
Code in Python by Mikołaj Biesaga, The Robert Zajonc Institute for Social Studies, University of Warsaw. GitHub repository: https://github.com/MikoBie/reddit
The Python code associated with this study can be found here: https://github.com/ melodyspr/parenting_reddit
Code in Python by Tawfiq Ammari, School of Information, University of Michigan. GitHub repository: https://github.com/tawfiqam/Parenting-Reddit
ACKNOWLEDGMENTSWe would like to thank Geoffrey Cideron for his useful suggestions throughout this work.This publication has emanated from research conducted with the financial support of Science Foundation Ireland under Grant number 18/CRT/6049 and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 802421).
Pseudonymous Parents: Comparing Parenting Roles and Identities on the Mommit and Daddit Subreddits. Tawfiq Ammari, Sarita Schoenebeck, Daniel M Romero, 10.1145/3173574.3174063Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems (CHI '18). the 2018 CHI Conference on Human Factors in Computing Systems (CHI '18)New York, NY, USAMontreal QC, Canada2018
The Pushshift Reddit Dataset. Jason Baumgartner, Savvas Zannettou, Brian Keegan, Megan Squire, Jeremy Blackburn, Proceedings of the Fourteenth International AAAI Conference on Web and Social Media, ICWSM 2020, Held Virtually. Munmun De Choudhury, Rumi Chunara, Aron Culotta, Brooke Foucault, Welles , the Fourteenth International AAAI Conference on Web and Social Media, ICWSM 2020, Held VirtuallyAtlanta, Georgia, USA; Palo Alto, CAAAAI Press2020. June 8-11, 2020
Jessica Benjamin, Authority and the Family Revisited: Or, a World without Fathers? New German Critique Winter. 1978. 197813
Natural Language Processing with Python: Analyzing Text with the Natural Language Toolkit. Steven Bird, Ewan Klein, Edward Loper, 2009O'Reilly, Beijing
Latent dirichlet allocation. Andrew Y David M Blei, Michael I Ng, Jordan, Journal of machine Learning research. 32003. 2003Publisher: JMLR. org
The context and content of social identity threat. Naomi Nyla R Branscombe, Russell Ellemers, Bertjan Spears, Doosje, Social identity: Context, commitment. Naomi Ellemers, Russell Spears, Bertjan Doosje, Oxford, UK1999Blackwell Science
The Second Shift: Working Parents and the Revolution at Home. Julie Brines, Arlie Hochschild, Anne Machung, Journal of Marriage and Family. 521990. 1990Publisher: National Council on Family Relations
Paternal involvement with children: The influence of gender ideologies. Ronald E Bulanda, Journal of Marriage and Family. 662004. 2004Wiley Online Library
What's all the talk about? Topic modelling in a mental health Internet support group. Bradley Carron-Arthur, Julia Reynolds, Kylie Bennett, Anthony Bennett, Kathleen M Griffiths, Publisher: BioMed Central. 162016. 2016BMC psychiatry
6% of online adults are reddit users. Maeve Duggan, Aaron Smith, Pew Internet & American Life Project. 32013. 2013
Gender stereotypes stem from the distribution of women and men into social roles. Alice H Eagly, Valerie J Steffen, Journal of personality and social psychology. 467351984. 1984American Psychological Association
Gender stereotypes. Naomi Ellemers, Annual review of psychology. 692018. 2018
IZA Discussion Papers 7037. Marta Favara, The Cost of Acting "Girly": Gender Stereotypes and Educational Choices. 2012Institute of Labor Economics (IZA
Because Dads Change Diapers Too": Negotiating Gendered Parenting Discourses on Reddit Parenting Forums. Hannah Feldman, Canadian Journal of Family and Youth/Le Journal Canadien de Famille et de la Jeunesse. 132021. 2021
WordNet: An Electronic Lexical Database. Christiane Fellbaum1998MIT PressCambridge, MA
Dirk Hovy, Text Analysis in Python for Social Scientists: Discovery and Exploration. Cambridge, UK.Cambridge University Press2020
Definition and assessment of accuracy in social stereotypes. M Charles, Bernadette Judd, Park, Psychological review. 1001091993. 1993American Psychological Association
Social identity performance: Extending the strategic side of SIDE. Olivier Klein, Russell Spears, Stephen Reicher, Personality and social psychology review. 112007. 2007Sage Publications
Sex differences and group argument: A theoretical framework and empirical investigation. Renee A Meyers, Dale E Brashers, Latonia Winston, Lindsay Grob, Communication studies. 481997. 1997Publisher: Taylor & Francis
WordNet: A Lexical Database for English. A George, Miller, 10.1145/219717.219748Commun. ACM. 381995. nov 1995
Division of labor among lesbian and heterosexual parenting couples: Correlates of specialized versus shared patterns. Charlotte J Patterson, Erin L Sutfin, Megan Fulcher, Journal of Adult Development. 112004. 2004Springer
Scikit-learn: Machine learning in Python. Fabian Pedregosa, Gaël Varoquaux, Alexandre Gramfort, Vincent Michel, Bertrand Thirion, Olivier Grisel, Mathieu Blondel, Peter Prettenhofer, Ron Weiss, 2825-2830. Publisher: JMLR. orgJournal of machine Learning research. 122011. 2011Vincent Dubourg, and others
Behavior online: Does anonymous computer communication reduce gender inequality?. Tom Postmes, Russell Spears, Personality and Social Psychology Bulletin. 282002. 2002Sage Publications Sage CA
Women's ideals for masculinity across social contexts: Patriarchal agentic masculinity is valued in work, family, and romance but communal masculinity in friendship. Michael Quayle, Graham Lindegger, Kirsty Brittain, Neesa Nabee, Charlene Cole, Sex roles. 782018. 2018Springer
When do fathers care? Mothers' economic contribution and fathers' involvement in child care. Sara Raley, Suzanne M Bianchi, Wendy Wang, Amer. J. Sociology. 1172012. 2012University of Chicago Press
Software Framework for Topic Modelling with Large Corpora. Radim Řehůřek, Petr Sojka, Proceedings of the LREC 2010 Workshop on New Challenges for NLP Frameworks. the LREC 2010 Workshop on New Challenges for NLP FrameworksValletta, Malta2010
Exploring the Space of Topic Coherence Measures. Michael Röder, Andreas Both, Alexander Hinneburg, 10.1145/2684822.2685324Proceedings of the Eighth ACM International Conference on Web Search and Data Mining. the Eighth ACM International Conference on Web Search and Data MiningShanghai, China; New York, NY, USAAssociation for Computing Machinery2015WSDM '15)
Pulling out the stops: Rethinking stopword removal for topic models. Alexandra Schofield, Måns Magnusson, David Mimno, Proceedings of the 15th Conference of the European Chapter. Short Papers. the 15th Conference of the European ChapterStroudsburg, PAAssociation for Computational Linguistics20172
Social identity and intergroup behaviour. Henri Tajfel, Social science information. 131974. 1974Sage Publications
An integrative theory of intergroup conflict. Organizational identity: A reader. Henri Tajfel, John C Turner, William G Austin, Stephen Worchel, 1979. 197956
Social influence. John C Turner, 1991Thomson Brooks/Cole Publishing CoPacific Grove, CA
Rediscovering the social group: A self-categorization theory. Michael A John C Turner, Penelope J Hogg, Stephen D Oakes, Margaret S Reicher, Wetherell, Basil Blackwell. 1987
. Guido Van Rossum, Fred L Drake, 2009PYTHON 2.6 reference manual
Gender and parenting: Effects of parenting failures on evaluations of mothers and fathers. Adrian J Villicana, Donna M Garcia, Monica Biernat, Group Processes & Intergroup Relations. 202017. 2017Sage Publications Sage UK
How involved is involved fathering? An exploration of the contemporary culture of fatherhood. Glenda Wall, Stephanie Arnold, Gender & Society. 212007. 2007Sage Publications Sage CA
Topic Modeling: Beyond Bag-of-Words. M Hanna, Wallach, 10.1145/1143844.1143967Proceedings of the 23rd International Conference on Machine Learning. the 23rd International Conference on Machine LearningPittsburgh, Pennsylvania, USA; New York, NY, USAAssociation for Computing Machinery2006ICML '06)
| [
0.03053411841392517,
-0.14491578936576843,
-0.07852528989315033,
0.029067980125546455,
0.09910745918750763,
0.008373193442821503,
0.0040049124509096146,
0.11113950610160828,
0.1309448480606079,
-0.012790311127901077,
-0.002405609469860792,
-0.06649723649024963,
0.15284855663776398,
0.05921... |
Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.
EE19 COST-EFFECTIVENESS ANALYSIS OF NONPHARMACEUTICAL INTERVENTIONS COMBINED WITH INACTIVATED VACCINATION AND ORAL MEDICINE IN CHINA
Fu F, 1 Zhao J, 1 Wei X, 2 Han P, 1 Yang L, 1 Ren T, 1 Zhan S, 1 Li L 1 1 Peking University, BEIJING, China, 2 London School of Hygiene & Tropical Medicine, London, UK Objectives: Various interventions were used to control the COVID-19 pandemic and protect population health, including vaccination, medication and nonpharmaceutical interventions (NPIs). This study aims to examine the cost-effectiveness of different combinations of NPIs (including social distancing, mask wearing, tracing-testingisolation, mass testing, and lockdown), oral medicine (Paxlovid), and vaccination (including two-dose and three-dose vaccination) under the Delta and Omicron pandemic in China. Methods: We constructed a Markov model using a SIRI structure with a one-week cycle length over one-year time horizon to estimate the costeffectiveness of different combinations in China from societal perspective. Effectiveness of interventions, disease transition probabilities and costs were from published data, quality-adjusted life years (QALYs) gained and incremental costeffectiveness ratios (ICER) and net monetary benefits were calculated for one-year time horizon. One-way and probabilistic sensitivity analyses were performed to test the robustness of the model. Scenario analysis was developed to examine different situations under the Omicron pandemic. Results: Under the Delta pandemic, implementing the combination of social distancing, mask wearing, mass testing and three-dose vaccination was the optimal strategy, with cost at $11165635.33 and utility of 94309.94 QALYs, and had 60% probability of being cost-effective compared with other strategies. Three-dose vaccination combinations were better than twodose combinations. Under the Omicron pandemic, antigen testing was better than nucleic testing by avoiding cross infections; second, adding Paxlovid or lockdown to the combined intervention strategies could increase limited health outcomes at huge cost and thus were not cost-effective; last, encouraging patients to stay at home can save societal costs compared with concentrated quarantine at hospitals. Conclusions: Three-dose vaccination and self-quarantine of asymptomatic and mild cases can save total costs. Under the Omicron pandemic outbreak, antigen testing is a better way to control the pandemic, and adding Paxlovid or lockdown to intervention combinations is not cost-effective. Objectives: Hepatitis C Virus (HCV) is a significant global health issue that persists despite the availability of curative treatment options with Direct Acting Antivirals (DAAs). The objective of this study is to describe and analyze the utilization, reimbursement, and price trends of HCV medications in the Medicaid-covered population. Methods: The primary data source was the state Medicaid drug utilization pharmacy claim files collected by the Centers for Medicaid and Medicare Services (CMS) from 2001 to 2021. A longitudinal retrospective and descriptive study was conducted to examine the annual secular trends of HCV medication utilization, reimbursement, and cost per prescription (proxy of price). The study evaluated all medications authorized for HCV treatment in the US, such as ribavirin (RBV), pegylated interferon alfa-2a (PEG-INFA2a), and DAA brand and generics (e.g., Boceprevir, Telaprevir, Simeprevir, Sofosbuvir, Ledipasvir/Sofosbuvir, Elbasvir/Grazoprevir, Daclatasvir, Sofosbuvir/Velpatasvir, and Glecaprevir/Pibrentasvir). The annual total numbers were calculated for number of prescriptions, reimbursements, and prices for each medication. Results: The utilization of conventional PEG-INFA2a and RBV reduced as the newer DAAs were introduced. In 2011, the total number of prescriptions for RBV, PEG-INFA2a, and DAAs were 103,358, 192,529, and 12,074, respectively; while in 2021, they were 1,600, 1,215, and 119,496, respectively. New DAAs agents led to the discontinuation of several DAAs agents due to market competition and lower utilization. The overall cost of PEG-INFA2a and RBV was much lower than DAAs, averaging around $2,945, $797, and $16,725, respectively, resulting in a much higher reimbursement for DAAs. The DAAs agent with the highest total annual reimbursement is Harvoni, with over $2 billion in both 2014 and 2015. Conclusions: Despite the introduction of multiple DAAs agents, the drug prices remained high and unchanged during the study period. The increase in HCV incidence cases in recent years indicates accessibility issues for costly and effective DAAs medications. Objectives: The aim of this analysis is to compare information regarding COVID-19 premature mortality productivity costs/ losses in Brazil. Methods: The states (S1 versus S2) in northern Brazil randomly chosen had criteria of similarity, tropical climate in most of the study period and population number. The study was carried out from March 2020 through November 2021 (20 months ). The reference of salaries to calculate possible losses due to deaths was obtained through accredited institutions, paylab, that study this specific information. Scenario A (Sc. A) = salary R$ 8.613,17 / month , scenario B (Sc. B) R$ 1.281,51 / month. Worker's age range from 15 to 64 years. The regional gross domestic product (GDP) was not used due to biases. Results: S1, 4,059 million inhabitants, 419,077 cases of confirmed COVID-19 , 8,948 deaths . In the following scenario, salary R$ 8,613.17 / month, (S1, Sc. A) the accumulated losses totaled R$ 1, 541,412,903.20 (USD 280,256,891.49 at the rate 1 USD = 5,50 BRL), and (S1, Sc. B) totaled R$ 229,339,029.60 (USD 41,698,005.38). S2, 3,561 million inhabitants, 382,265 cases of confirmed COVID-19, 7,518 deaths . Considering the following scenario, salary R$ 8,613.17 / month, (S2, Sc. A) the accumulated losses totaled R$ 1, 295,076,241.20 (USD 235,468,407.49 at the rate 1 USD = 5,50 BRL), and (S2, Sc. B) R$ 192,687,843.60 (USD 35,034,153.38). Conclusions: We estimate premature mortality productivity costs associated with COVID-19 across two states in northern Brazil are high and the conclusion is that the productivity losses based on regional GDP are difficult to detail. Further studies are needed to mitigate this situation. Objectives: Non-union is a common complication following long bone fractures, often requiring significant incremental healthcare resources. The payer cost of long bone non-union in patients with or without concurrent infection is not well documented. Our study evaluated 2-year incremental healthcare costs of non-union in patients with fractures. Methods: Patients within IBM® MarketScan® Commercial Claims and Encounters database with long bone (femur, humerus or tibia) fracture in the inpatient setting, and a surgical fracture repair procedure, from Q4 2015 to most recent, were identified. Exclusion criteria included: polytrauma and amputation at index. Outcomes: diagnosis of non-union in the 2-year post-index, concurrent infection, reoperation, and total healthcare costs. Variables: age, gender, comorbidities, fracture characteristics and severity. Descriptive analyses were performed on all three cohorts separately. Crude and adjusted rates of non-union (using Poisson regressions with log link) were calculated. Marginal, incremental cost of care associated with non-union, infection and reoperation, were estimated using a Generalized Linear Model (GLM) with log link and gamma distribution. Results: 12,770, 13,504 and 4,805 patients with surgically-treated femoral, tibial and humeral fractures were identified, respectively. Two-year post-index rates of non-union reached 8.5% (8.0%-9.1%) (femoral fracture), 9.1% (8.6%-9.7%) (tibial fracture), and 7.2% (6.4%-8.1%) in humeral fracture cases. Infected non-unions affected , 1% of femoral and humeral fractures, and 2% for tibial fractures. All tibial non-union patients were reoperated by 2 years, however only 71% of femoral non-unions, and 68% of humeral non-unions were already reoperated. The increased marginal cost of femoral, tibial and humeral non-union at 2-years post-index averaged $45,633 ($23,913-$67,352), $40,409 ($30,295-$50,523) and $33,308 ($14,603-$52,013), respectively, prior to reoperation and without concurrent infection. Reoperations added $16K-$34K incremental costs. When infection was also present, costs increased by $46K-$87K. Conclusions: Nonunion is associated with significant incremental costs. Without concurrent infection, non-union conditions add between $33K-$46K costs. Concurrent infection results in an additional $46K-$87K. Objectives: Schizophrenia is associated with substantial economic burden on the US health care system. Olanzapine (OLZ), a 2 nd generation antipsychotic (AP) treatment has been an effective treatment for patients with schizophrenia has been associated with weight gain and cardiometabolic sequelae. During 2021, the US Food and Drug Administration approved a combination of OLZ and samidorphan (OLZ/SAM [LYBALVI®]) for the treatment of adults diagnosed with schizophrenia or bipolar I disorder. OLZ/SAM has demonstrated clinical efficacy of olanzapine but with less weight gain. The rates of discontinuations to AP are very high in patients with schizophrenia, leading to relapse rates. It is important to understand the potential economic impacts of relapse rates in schizophrenia patients initiated on OLZ/SAM versus OLZ to inform health care decision makers. Methods: A decision tree model from a US payer perspective was developed to examine the difference of relapse rates VALUE IN HEALTH -JUNE 2023 S63
EE22 RISK FACTORS AND HEALTHCARE COSTS ASSOCIATED WITH LONG BONE FRACTURE NON-UNION -A US CLAIMS DATABASE ANALYSIS
EE23
EE20 UTILIZATION, REIMBURSEMENTS AND PRICES TRENDS OF HEPATITIS C VIRUS DRUGS IN THE US MEDICAID PROGRAMS FROM 2001 TO 2021 Gari M, 1 Alsuhibani A, 2 Alashgar A, 2 Guo JJ 2 1 University of Cincinnati, James L. Winkle College of Pharmacy, Crestview Hills, KY, USA, 2 University of Cincinnati, James L. Winkle College of Pharmacy, Cincinnati, OH, USA
EE21 COVID-19 PREMATURE MORTALITY PRODUCTIVITY LOSSES: REAL WORLD INFORMATION ANALYSIS Tanaka E, 1 Tanaka GK, 2 Kuabara R, 3 Massuda EM, 4 Assunção-Costa L, 5 Tafla C, 6 Nunes RMZ, 7 Furlan LHP 8 1 TNK INSTITUTION, CURITIBA , PR, Brazil, 2 TNK Health Economics Outcome Research Brazil, CURITIBA, Brazil, 3 GOIANIA STATE HEALTH CARE, GOIANIA, GO, Brazil, 4 UniCesumar, MARINGÁ PR, Brazil, 5 STATE UNIVERSITY OF SOUTHWEST BAHIA, Salvador, BA, Brazil, 6 Nilo Health Care, Curitiba , PR, Brazil, 7 UNIMED JOÃO PESSOA, JOÃO PESSOA , PB, Brazil, 8 UNIMED FED PR, CURITIBA, Brazil
Vanderkarr M, 1 Ruppenkamp J, 1 Vanderkarr M, 2 Holy C, 3 Blauth M 4 Johnson & Johnson MedTech, New Brunswick, NJ, USA, 2 DePuy Synthes, Inc., Bay Village, OH, USA, 3 Johnson & Johnson, Somerville, MA, USA, 4 DePuy Synthes, Solothurn, Switzerland1
ECONOMIC IMPACT OF DISCONTINUATION AND RELAPSE RATES AMONG PATIENTS WITH SCHIZOPHRENIA NEWLY INITIATED ON LYBALVI VERSUS OLANZAPINE DURING FIRST YEAR USE Ching R, 1 Uhlyarik A, 2 Ahmed S, 2 Rashid N 3 Keck Graduate Institute, School of Pharmacy and Health Sciences, Sausalito, CA, USA, 2 Keck Graduate Institute, School of Pharmacy and Health Sciences, Claremont, CA, USA, 3 Keck Graduate Institute, School of Pharmacy and Health Sciences, Irvine, CA, USA1
| [
0.020897146314382553,
0.0988888069987297,
0.011220918036997318,
0.05763929337263107,
0.08126574754714966,
0.13411027193069458,
-0.06611014157533646,
0.1540243923664093,
0.16524292528629303,
0.044723011553287506,
0.044259801506996155,
-0.12666194140911102,
0.10593370348215103,
0.06989637762... |
10.1093/ndt/gfab104
1
Hospital General Universitario Ciudad Real, Nephrology, Ciudad Real, Spain BACKGROUND AND AIMS: Management of ANCA-Associated Vasculitis (AAV) is in constant update. The aim of the study is to describe our experience as a territorial reference center with this systemic disease and to analyze which factors have a significant influence on the development of end-stage renal disease (ESRD). METHOD: Retrospective observational study. All the patients who developed AAV in our center between 2010 and 2019 were included. Demographic variables (age, sex), renal function, other vasculitis related symptoms, induction and maintenance therapy, response degree and follow-up were collected. Categorical variables are expressed as percentages and compared using Chi2 test. Quantitative variables are expressed as mean 6 standard deviation and compared using Mann-Whitney U test. Cox regression was performed to determine independent predictors of ESRD. Kaplan-Meier was used to estimate ESRD-free survival. Statistical significance for a value of p< 0,05. Statistical analysis was performed with SPSS 25.0. RESULTS: 45 patients were analyzed, with an average age of 70 6 11 years. 62.2% were men. Mean time of follow-up 36 6 31.6 months. 37.8% presented c-ANCA autoantibodies and 57.8% p-ANCA. Mean baseline serum creatinine level was 5.51 6 3.65 mg/dl and proteinuria 2.82 6 2.48 g/24h. 77.8% received cyclophosphamide as induction immunosuppressive treatment whereas 13.3% rituximab. 50% received azathioprine, 36.1% mycophenolate and 13.9% rituximab as maintenance treatment. 37.8% patients underwent plasma exchange therapy and 44.4% hemodialysis. Complete remission was achieved by 13.3% of patients, while 57.8% partial remission. 28.9% had absence of remission. 28.9% achieved ESRD. ESRD was associated with undergoing hemodialysis (69.2% vs 30.8% p=0.033), to the type of response (complete 7.7% vs partial 23.1% vs no response 69.2%), baseline creatinine level (8.36 6 5.44 vs 4.35 6 1.64 mg/dl p=0.011), creatinine 6 months after induction treatment (4.3 6 2.05 vs 2.04 6 0.77 mg/dl p=0.001) and at the end of follow-up (6.33 6 2.47 mg/dl vs 2.2 6 1.29 mg/dl p=0.001) and also to baseline proteinuria (4.21 6 3.12 vs 2.25 6 1.96 p=0.003), proteinuria 6 months after induction treatment (1.4 6 1.46 vs 0.58 6 0.73 g/ 24h p=0.014) and at the end of follow-up (2.48 6 1.9 vs 1.12 6 1.64 p=0.001). Logistic regression only showed end of follow up serum creatinine level as an independent risk factor of ESRD (OR3.74 IC 95% 1.01-13.75 p=0.047). ESRD-free survival chance after 5 of follow-up was 67%. CONCLUSION: Only serum creatinine level at the end of follow-up could be found as an associated factor with ESRD. Greater number of patients would be needed in order to obtain other factors leading to ESRD in patients with AAV. BACKGROUND AND AIMS: Urine sediment microscopy is mostly abandoned by nephrologists nowadays, however it is an important diagnostic tool in kidney and urinary tract diseases. The aim of this study is to emphasize the benefits of urine microscopy performed by a nephrologist. METHOD: A prospective cohort study at Pauls Stradins Clinical University Hospital Nephrology center included patients with histologically confirmed diagnosis of IgA nephropathy from 1st January 2020 till December 2020. Appropriately collected urine samples were examined using manual microscopy within an hour after sample collection and by automated urinalysis. Samples were centrifuged at 4000 rpm for 4 minutes, the supernatant urine was carefully decanted, 1 -1,5 ml of the left urine was mixed by gentle agitation and placed on a standard glass slide with a cover slip. Sample examination was performed using low (magnification x10) and high power (magnification x40) using brightfield microscopy with a minimum of 10 fields. RESULTS: A total of 37 patients (24 men, mean age 42.7 6 10.9 years) were included in the study. 59.5 % of patients (n = 22) had hematuria based on automated urine sediment analysis and 62.2 % (n = 23) of patients had hematuria based on manual urine microscopy. 45.9 % of patients (n=17) had dysmorphic erythrocytes, 13.5 % of patients (n = 5) had isomorphic red blood cells (RBC) and 40.5 % of patients (n = 15) did not have RBC in urine samples by manual urine microscopy. 54.2 % (13/24) of men and 30.8 % (4/13) of women had dysmorphic RBC in urine. CONCLUSION: Manual urine sediment examination was more sensitive than automated analysis. Majority of IgA nephropathy patients have active urine sediment with hematuria and dysmorphic RBC. Manual microscopy remains an effective and reliable method that can be easily and quickly performed by nephrologists.
MO320 LUPUS FLARE MIMICKING COVID-19 INFECTION: A CASE REPORT
Meryem Sabah 1 , Fatimzahra Jabrane 1 , Hiba El oury 1 , Mohamed Amine Khalfaoui 1 , Nasreddine Chehab 1 , Ghizlaine Medkouri 1 1 Mohamed VI University of health sciences, Nephrology, Casablanca, Morocco BACKGROUND AND AIMS: The world is in midst of the coronavirus disease 2019 (COVID-19) pandemic. METHOD: Studies of the COVID-19 pathophysiology show that its defining character is an overt inflammatory response, similar to cytokine release syndrome, causing a dysregulated immune response. Systemic lupus erythematosus (SLE) is also a disease of immune dysregulation contributing to multisystem compromise. There is very little literature to suggest that COVID-19 could potentially mimick SLE presentation. We describe the case of a female patient who presented with typical Covid19 clinical features, later diagnosed as a new-onset SLE. RESULTS: A 51-year-old female presented with fever, dyspnea, cough and desaturation at the emergency room. Chest computed tomography scan showed bilateral areas of ground-glass opacities in a peripheral distribution. She was admitted in a Covid-19 ICU. She then progressed to severe acute respiratory distress syndrome, and worsening renal function with proteinuria and hematuria. Further investigations showed bilateral pleural effusions, ascites, leukopenia and thrombocytopenia, positive antinuclear and anti-double-stranded DNA antibodies, and low levels of C3 and C4. SARS-Cov-2 PCR was negative twice. After the establishment of the diagnosis, the patient was transferred to the internal medicine department where she received decongestive therapy, intravenous (IV) pulses of methylprednisolone, along with hydroxychloroquine. She improved sustainably and was discharged after two weeks.
MO319 BEDSIDE URINE SEDIMENT EXAMINATION IN IMMUNOGLOBULIN A NEPHROPATHY PATIENTS PERFORMED BY NEPHROLOGISTS Pauls Stradins Clinical University Hospital, Nephrology department, Riga, Latvia, 2 Riga Stradiņ s University, Riga, Latvia and 3 University of Latvia, Riga, LatviaAnna Popova 1,2,3 , Karlis Racenis 1,2 , Anna Jana Saulite 1,2 , Aiga Vasilvolfa 1,2,3 ,
Aivars Petersons 1,2 , Harijs Cernevskis 1,2 , Viktorija Kuzema 1,2
1
CONCLUSION: A patient with new-onset lupus presented with clinical features typically seen in COVID-19 patients. The adequate management of the patient was delayed due to the misguided diagnosis. MO321 THE USE OF INTRAVENOUS CYCLOPHOSPHAMIDE AND ORAL STEROIDS IN PRIMARY MEMBRANOUS NEPHROPATHY WITH ADVANCED KIDNEY DISEASE Omar Ragy 1 , Patrick Hamilton 2 , Durga Kanigicherla 3 Manchester Royal Infirmary, Manchester, United Kingdom, 2 Manchester Royal Infirmary, Renal, United Kingdom and 3 Manchester Royal Infirmary, Renal, Manchester, United Kingdom BACKGROUND AND AIMS: International guidelines do not recommend specific use of immunosuppression treatment in membranous nephropathy patients presenting with an estimated glomerular filtration rate of <30ml/min/1.73m2. This is due to the scant published evidence of effectiveness and uncertainty around toxic effects at this stage. In this study, we sought to examine the safety and effectiveness of combined Nephrology Dialysis Transplantation Abstracts 10.1093/ndt/gfab104 | i2331
| [
0.04889883100986481,
-0.0595945306122303,
0.02161947637796402,
-0.0016755550168454647,
-0.13353410363197327,
-0.002164495177567005,
-0.11820869147777557,
0.17549189925193787,
0.10580630600452423,
0.06252685189247131,
-0.024691002443432808,
-0.0074102855287492275,
0.008896680548787117,
0.03... |
Angelo Silverio
Department of Medicine, Surgery, and Dentistry
Scuola Medica Salernitana'
University of Salerno
Baronissi, SalernoItaly
Fernando Scudiero
Division of Cardiology, 'Bolognini' Hospital
ASST Bergamo EST
SeriateItaly
Marco Di Maio
Department of Medicine, Surgery, and Dentistry
Scuola Medica Salernitana'
University of Salerno
Baronissi, SalernoItaly
Vincenzo Russo
Chair of Cardiology
Department of Translational Medical Sciences
University of Campania 'Luigi Vanvitelli'-Monaldi and Cotugno Hospital
NaplesItaly
Francesco Paolo Cancro
Department of Medicine, Surgery, and Dentistry
Scuola Medica Salernitana'
University of Salerno
Baronissi, SalernoItaly
Luca Esposito
Department of Medicine, Surgery, and Dentistry
Scuola Medica Salernitana'
University of Salerno
Baronissi, SalernoItaly
Martina Sordillo
Department of Medicine, Surgery, and Dentistry
Scuola Medica Salernitana'
University of Salerno
Baronissi, SalernoItaly
Iacopo Muraca
Division of Interventional Cardiology
Cardiothoracovascular Department
Careggi University Hospital
FlorenceItaly
Rodolfo Citro
Division of Cardiology, Cardiovascular and Thoracic Department
University Hospital 'San Giovanni di Dio e Ruggi D'Aragona'
SalernoItaly,
Guido Parodi
Cardiology Unit
ASL4 Liguria
Ospedali del Tigullio
Polo di LavagnaItaly
Carmine Vecchione
Department of Medicine, Surgery, and Dentistry
Scuola Medica Salernitana'
University of Salerno
Baronissi, SalernoItaly
Gennaro Galasso
Department of Medicine, Surgery, and Dentistry
Scuola Medica Salernitana'
University of Salerno
Baronissi, SalernoItaly
622 Long term prognostic impact of right ventricular dysfunction in patients with COVID-19
Aims: The characteristics and clinical course of hospitalized patients with Coronavirus disease 2019 (COVID-19) have been widely described, while long-term data are still poor. The aim of this study was to evaluate the long-term clinical outcome and its association with right ventricular (RV) dysfunction in hospitalized patients with COVID-19. Methods and results: This was a retrospective multicentre study of consecutive COVID-19 patients hospitalized at seven Italian Hospitals from 28 February to 20 April 2020. The study population was divided into two groups according to echocardiographic evidence of RV dysfunction defined by tricuspid annular plane systolic excursion (TAPSE) value <17 mm in accordance with the current guidelines. The primary study outcome was 1-year mortality. The study population consisted of 224 patients (mean age 69 6 14, male sex 62%); RV dysfunction was diagnosed in 63 cases (28%). Patients with RV dysfunction were older (75 vs. 67 years, P < 0.001) and showed a higher prevalence of coronary artery disease (27% vs. 11%, P ¼ 0.003), heart failure (5% vs. 22%; P < 0.001), chronic obstructive pulmonary disease (13% vs. 38%; P < 0.001), and chronic kidney disease (12% vs. 39%; P < 0.001). Left ventricular ejection fraction (LVEF) was significantly lower in patients with RV dysfunction that in those without (55% vs. 50%; P < 0.001). The rate of mortality at 1-year was significantly higher in patients with RV dysfunction as compared with those without (67% vs. 28%; P 0.001). After propensity score matching, patients with RV dysfunction showed a significantly lower long-term survival than patients without RV dysfunction (62% vs. 29%, P < 0.001). At multivariable Cox regression analysis, TAPSE, LVEF and acute respiratory distress syndrome during the hospitalization were independently associated with 1-year mortality (Table). Conclusions: RV dysfunction is a relatively common finding in hospitalized patients with COVID-19 and is independently associated with an higher risk of mortality at one-year follow-up. Recent data support the existence of a distinctive 'vascular' phenotype with the involvement of both pulmonary parenchyma and its circulation in COVID-19 pneumonia. Its prompt identification is important for the accurate management of COVID-19 patients. The aim is to analyse the pro and contra of the different modalities to identify the 'vascular' phenotype. Chest computed tomography scan and angiogram may quantify both parenchyma and vascular damage, but the presence of thrombosis of pulmonary micro-circulation may be missed. Increased D-dimer concentration confirms a thrombotic state, but it cannot localize the thrombus. An elevation of troponin concentration nonspecifically reflects cardiac injury. Echocardiogram and electrocardiogram provide specific signs of right ventricular pressure overload. This is particularly relevant for the 'vascular' phenotype which does not necessarily represent the result of thromboembolic venous complications but, more frequently, it is the result of pulmonary microcirculation thrombosis in situ and needs immediate therapeutic action.
404 Acute coronary syndromes after healing from COVID-19: report of the initial observation Most patients (pts) recover quickly; nevertheless, the potential long-term cardiovascular sequalae of COVID-19 remain currently unknown. The aim was to report cases of acute coronary syndromes (ACS) after healing from COVID-19 and their features at coronary angiography; secondary purpose was to hypothesize the underlying mechanisms. Methods and results: A retrospective study was performed by acquiring data from the electronic medical record. From January to June 2021, four hypertensive pts (64 6 17 years old; three males) with no history of CVDs and previous symptomatic SARS-CoV-2 infection (mean interval from first positive molecular swab 47 6 32 days; all recovered after 15 days with double negative swab) were admitted to the emergency department for ST-elevation myocardial infarction (3 anterior and one inferior). At admission, the SARS-CoV-2 molecular swab tested negative, left ventricle ejection fraction was 42 6 12%, troponin T and Nt-proBNP values were 47 6 24 ng/ l and 1180 6 978 ng/l, respectively. Emergency coronary angiography showed singlevessel acute thrombotic occlusion (in three cases of the anterior descending artery and in one case of the right coronary artery), with no evidence of atherosclerotic disease. Because of the high thrombotic burden, in all cases a mechanical thrombus aspiration system was used, tirofiban infusion started and no balloon angioplasty or drug-eluting stent implantation was necessary (Figures A-D). After 72 h, a second SARS-CoV-2 molecular swab tested also negative. In the following days, the pts gradually recovered and they were discharged home. Conclusions: These cases deserve specific considerations both on the pathophysiologic mechanisms of the ACS possibly related to SARS-CoV-2 and on the subsequent long-term sequelae. Among various pathophysiologic mechanisms proposed, the high affinity of the spike protein for the angiotensin converting enzyme two receptor (expressed by both cardiac and endothelial cells) could explain direct cardiac viral infection and vasculitis with possible development of thrombosis. The latter could contribute both to acute and long-term cardiac sequelae, even months after the acute infection, configuring a sort of 'cardiac post-Covid syndrome'. Whether and Abstracts G91
of Heart and Vessels, University of Insubria, Varese, Italy, 2 Department of Medicine and Surgery, University of Insubria, Varese, Italy, and 3 Department of Medicine and Cardiopulmonary Rehabilitation, Maugeri Care and Research Institutes, Tradate, Varese, Italy Aims: Severe pulmonary complications are well described in the coronavirus disease 2019 (COVID-19) and cardiovascular diseases (CVDs) have been documented as well.
407 Phenotypic heterogeneity of COVID-19 pneumonia: clinical and phatophysiologic relevance of the vascular phenotype Matteo Bertini 1 , Emanuele D'Aniello 1 , Luca Di Ienno 1 , Federico Gibiino 1 , Guido Tavazzi 2 , Carlo Alberto Volta 2 , Marco Contoli 3 , Alberto Papi 3 , Gianluca Campo 1 , Roberto Ferrari 4 , and Claudio Rapezzi 1,4 Cardiological Center, University of Ferrara, Italy, 2 Anaesthesia and Intensive Care Medicine, Universithy of Ferrara, Italy, 3 Malattie Dell'Apparato Respiratorio, University of Ferrara, Italy, and 4 Maria Cecilia Hospital, Cotignola, Italy1
| [
0.06921825557947159,
-0.0552588626742363,
-0.04230658710002899,
0.0043118856847286224,
-0.09348021447658539,
-0.03630029782652855,
-0.1804346889257431,
0.16601458191871643,
0.03675127401947975,
-0.07276175916194916,
0.015871522948145866,
0.011926469393074512,
0.046433597803115845,
0.092102... |
December 2021. 2021 Dec
Gynecology Dandale
A U
Department of Obstetrics and Gynecology
Dr. Aparna U. Dandale
LTMMC and LTMGH
Sion, MumbaiMaharashtraIndia
Int J Reprod Contracept Obstet Gynecol
1012December 2021. 2021 Dec10.18203/2320-1770.ijrcog20214649
INTRODUCTION
Meconium is a collection of secretions and desquamated cells from the digestive tract, and waste products from ingested amniotic fluid. It is a viscous, dark-green substance composed of intestinal epithelial cells, lanugo, mucus, and intestinal secretions. Water being the major liquid constituent (90%) and solid constituents (10%) consists of intestinal secretions, mucosal cells, and solid elements of swallowed amniotic fluid, such as proteins and lipids. Unlike stool, meconium is sterile and does not contain bacteria. outcome, in terms of five-minute Apgar scores <7 and an umbilical artery pH<7. 10. 1 Meconium and its effects on fetus and neonates have remained a cause of significant worry for both the obstetrician and neonatologists. There are still widespread debates with varied opinions regarding the optimum obstetrical approach, resuscitative measures at birth and management of critically ill neonates with MAS. With the recognition of role of chronic in utero hypoxia and associated perinatal asphyxia in pathogenesis of MAS, routine endotracheal suctioning is no longer recommended even in non-vigorous infants with MAS. Advent of newer therapies like inhaled no, surfactant, high-frequency ventilation and extracorporeal membrane oxygenation (ECMO) has resulted in tremendous improvements in MAS survival. 2
Pathogenesis of meconium passage in amniotic fluid
Meconium begins to appear in the fetal intestines by the 10 th week of life gradually increasing in amount to reach 200 gm at birth.
Lucas et al suggested that levels of "motilin" an intestinal hormone responsible for bowel peristalsis and defecation are lower in premature infants and higher in those who have passed meconium. It has been shown that infants with fetal distress had a four-fold elevation of cord plasma Motilin than normal. 3 Meconium passage is rare before term because of lack of integrated parasympathetic system which is stimulated by in utero hypoxia and acidosis leading increased peristalsis and relaxed anal sphincter causing meconium passage. Animal experiments shows that hypoxia causes deep intrauterine gasping and risk for aspiration. 4 Walker observed that Meconium appears as a result of interference with trans-placental transfer of oxygen. Critical oxygen level of umbilical venous blood was 30% or lower than fetus at term. 5 Desmond agreed with the Walker theory which postulated that:
Hypoxia→ reflex vagal stimulation→relaxation of anal sphincter→ meconium passage Factors that promote the passage of meconium in utero include the following: Pregnancy that lasts longer than 42 weeks or longer, secondary to a hypoxic stress, placental insufficiency, transient rise of pCO 2 or fall in the pO 2 in the umbilical arteries due to pressure in the umbilical cord without metabolic acidosis, maternal hypertension, preeclampsia, oligohydramnios, maternal drug abuse, especially of tobacco and cocaine, fetal distress during labour, transient pressure on the scalp during labour, amnionitis and iodiopathic. 6,7 Objectives
Primary objective
The primary objectives were to find the association of comorbidities in fetus who passed meconium in utero and to study fetomaternal risk factors associated with meconium passage in utero.
Secondary objective
Secondary objectives were to evaluate fetal outcomes in meconium-stained liquor.
METHODS
Study design
The study design was of hospital based prospective observational study
Study place
This study done in department of obstetrics and gynecology at Lokmanya Tilak municipal medical college and hospital, Sion, Mumbai, Maharashtra.
Study period
Study conducted from November 2017 to August 2019.
Sample size
The 200 patients were participated in the study.
Sampling unit
All antenatal women patients attending at our tertiary care centre in the department of obstetrics and gynecology in active phase of labour who fulfilled the inclusion criteria.
Selection criteria of patients
Inclusion criteria
Those who were willing to participate, 37 weeks gestation, Single term pregnancy, cephalic presentation, liquor meconium stained and women in active phase of labour were included in the study.
Exclusion criteria
Those who had pre-term delivery, breech presentation and multiple pregnancies were excluded from the study.
A predesigned pretested interview schedule questionnaire was prepared in accordance with study objectives. The questionnaire was prepared in English and interview was conducted in the language which they best understood.
The structured questionnaire was subjected for face and content validation by the department of obstetrics and gynecology. Permission to conduct the study and ethical clearance was obtained from the institutional ethics committee. Participants were fully informed about the purpose, procedures, and benefits of participation in the study through informed consent form. Participation in this study was voluntary. Participants were informed that all record pertaining to the study would be confidential, and that numbers instead of names would be used to identify the participants and data would be used for academic purpose only. Pre-tested questionnaire. Detailed history of mothers was recorded with emphasis on antepartum and intra-partum risk factors like medical disorders, obstetric complications, etc. Consistency of meconium was divided into, thick and moderate. Thick meconium was characterised by opaque and deep green coloured liquor whereas opalescent liquor with colour in between deep green and light-yellow green represents moderate meconium. Decision of mode of delivery was taken depending on stage of labour, FHR pattern, availability of operational theatre (OT), consent of patients and relatives. Amnioinfusion was done in patients with active and transition phase of labour with prophylactic antibiotic coverage. Maternal outcome in terms of mode of delivery and puerperal complications were recorded.
Individualised outcome of MSAF babies were noted with special emphasis on factors like Apgar score, need of resuscitation, duration of NICU stay, complications etc. Morbidity of neonates were noted with emphasis on MAS, RDS, hypoxic ischaemic encephalopathy (HIE), birth asphyxia, NICU admission, sepsis etc. Maternal and perinatal mortality was evaluated.
Operational definitions
Operational definitions were-active phase of labour: cervical dilatation 5-7 cm and transition phase of labour: cervical dilatation >8 cm. 8
RESULTS
Proportion of MSAF in present study
In center, 9821 deliveries were conducted from November 2017 to August 2019 out of which 1287 (13.11%) deliveries had MSAF. In this study that 112 (56%) patients had thick MSAF while 88 (44%) patients had moderate. In our study the overall neonatal complications were severe birth asphyxia (5), MAS (4), septicemia (5), HIE (3), RDS (9) and pulmonary hemorrhage (1). In our study 56% patients had thick MSAF while 44% patients had moderate MSAF and in study by Rajput et al 35% had thick while 21% had moderately meconiumstained liquor. 9 Here proportion of both thick and moderate meconium was higher than the study. Unnisa et al shows 44.5% were thickly Meconium stained. 10 Our study shows a greater number of women 71% with MSAF had gestational age 37-40 weeks and 29% were having gestational age >40 weeks. Unnisa et al 41.4% had gestational ages of 39-39.6 weeks. 10 Mundhra et al 50% cases had gestational ages of more than 40 weeks. Here <40 weeks gestational age women are more as compared to study. 11 It was observed in the present study that MSAF was more common in maternal high-risk factors like Post-dated pregnancy 29%, oligohydramnios 19%, pregnancy induced hypertension 16.5%, anaemia 7%, PROM 5%, antepartum haemorrhage 2%. Rajput et al observed Oligohydramnios 30%; PIH 24%, anaemia 14%, and antepartum haemorrhage 4%. Results are similar to study of Rajput et al. 9 Priyadharshini et al post-dated pregnancy (82), PIH (12), Rh isoimmunisation (12), oligohydramnios (9), GDM (8), heart disease (5), higher maternal age (5), chronic respiratory disease (4), teen age pregnancy (3), cholestasis of pregnancy (3). The intra-partum risk factors were prolonged PROM (9), IUGR (8), prolonged labour (3), circumvallate placenta (1), ileal atresia (1), premature atrial contraction of fetus (1). 12 Mundhra et al PIH seen in 16.97%. 11 In the present study, patients who were in active phase of labour (before 7 cm dilatation of cervix) were 57.5% and who crossed 8 cm dilatation of cervix, were 42.5%. In active phase of labour, meconium-stained liquor was detected either with spontaneous or artificial rupture of membrane.
In our study amnioinfusion was done in 38% patients. The current study shows that 3 (1.5%) women had PPH, of which 2 had traumatic PPH after forceps application due to cervical tear and 1 had atonic PPH. Another 3 patients had wound infection post LSCS; one had Chorioamnionitis and one puerperal sepsis. Chorioamnionitis, puerperal sepsis, wound infection patients were managed well with higher antibiotics. We had no maternal mortality. Thick MSAF was associated with more maternal complication than moderate MSAF. we had less maternal complications as compared to study of Pushpa et al having tonic PPH occurred in 8% women. 13
Limitation
In 124 (62%) patients amnioinfusion could not be done as the duration between detection of MSAF and delivery was short. Some patients were already in second stage of labour and delivered normally, few required instrumental delivery to cut short second stage of labour and few underwent LSCS. Limitation of advanced investigations like fetal scalp blood testing.
CONCLUSION
Early identification of MSAF in labouring women during intra-partum monitoring and availability of operation theatre for immediate intervention is required to reduce the perinatal morbidity and mortality. It is important to register all high-risk patients at tertiary centre with NICU availability. Also, it is mandatory to have NICU facilities in all maternity homes where babies with MSAF are delivered. This study advances our knowledge and understanding in the field of presence of MSAF in terms of need of close monitoring of fetus, mindful intervention, and presence of skilled neonatologist, obstetrician and anaesthetist at the time of birth so as to decrease perinatal morbidity and mortality.
Table 1 :
1Distribution of patients according to gestational age at delivery.Figure 1: Proportion of MSAF in present study.In above table, out of 142 patients, 80 (71.4%) patients had thick MSAF and 62 (70.4%) patients had moderate MSAF with gestational age of 37 to 40 weeks. After 40 weeks of gestation 32 (28.5%) patients had thick MSAF while 26 (29.5%) patients had moderate MSAF.Gestational
age at
delivery
(Weeks)
Thick,
(n=112)
Moderate,
(n=88)
Total,
(n=200)
N
%
N %
N
%
37-40
80
71.4 62 70.4
142 71
>40
32
28.5 26 29.5
58
29
Total
112
100 88 100
200 100
Table 2 :
2Maternal risk factors in patients with MSAF, (n=200).Maternal risk
factors
associated
with MSAF
Thick,
(n=112)
Moderate,
(n=88)
Total,
(n=200)
N %
N %
N
%
Postdate
pregnancy
32 28.5 26 29.5
58
29
Oligohydram
nios
23 20.5 15 17
38
19
PIH
21 18.7 12 13.6
33
16.5
Anemia
8
7.1
6
6.8
14
7
PROM
6
5.3
4
4.5
10
5
Antepartum
hemorrhage
4
3.5
0
0
4
2
Total no. of
maternal
complications
94 83.9 63 71.5
157 78.5
In this study, 94 (83.9%) mothers of thick meconium and
63 (71.5%) of moderate meconium were having maternal
high-risk factors. Overall (i.e., in thick and moderate
Meconium) most common maternal high-risk factors was
post-dated pregnancy 58 (29%) followed by
oligohydramnios 38 (19%), pregnancy induced
hypertension 33 (16.5), anaemia 14 (7%), PROM 10 (5%),
antepartum haemorrhage 4 (2%) consisting of abruption
placenta 3, placenta previa 1.
Table 3 :
3Distribution of patients according to dilatation of cervix at the time of detection of meconium.Stage of
labour
Thick,
(n=112)
Moderate,
(n=88)
Total,
(n=200)
N
%
N
%
N
%
Active
phase
68
60.7 47
53.4 115 57.5
Transition
phase
44
39.2 41
46.5 85
42.5
Total
112 100 88
100 200 100
Above table shows patients who were in active phase of
labour (before 7 cm dilatation of cervix) 68 (60.7%) were
found to have thick and 47 (53.4%) moderate MSAF. In
patients who crossed 8 cm dilatation of cervix, 44 (39.2%)
were found to be with thick MSAF and 41 (46.5%) were
with moderate MSAF.
Table 4 :
4Distribution of patients according to
amnioinfusion.
Amnioin-
fusion
Thick,
(n=112)
Moderate,
(n=88)
Total,
(n=200)
N
%
N
%
N
%
Received 48
42.8 28
31.8 76
38
Not
received
64
57.1 60
68.1 124 62
Total
112
100 88
100 200 100
Table 5 :
5Distribution of MSAF patients according to
indications for LSCS, (n=143).
Indications
for LSCS
Thick,
(n=73)
Moderate,
(n=70)
Total,
(n=143)
N %
N %
N
%
Fetal distress 34 46.5 30 42.8
64
44.7
Abnormal
labour
14 19.1 15 21.4
29
20.3
MSAF in
early active
labour
19 26
21 30
40
27.9
Antepartum
hemorrhage
4
5.4
0
0
4
2.8
IUGR with
Doppler
changes
1
1.3
4
5.7
5
3.5
Cord
prolapsed
1
1.3
0
0
1
0.7
Total
73 100 70 100
143 100
Most common indication for LSCS was fetal distress in
both meconium type i.e., 34 (46.5%) in thick MSAF
patients and 30 (42.8%) in moderate MSAF patients, other
indications being MSAF in early active labour 19 (26%),
abnormal labour 14 (19.1%), antepartum haemorrhage 4
(5.4%), IUGR with Doppler changes and cord prolapsed
both were 1 (1.3%). In moderate MSAF patients' other
indications after fetal distress were, MSAF in early active
labour 21 (30%), abnormal labour 15 (21.4%) and IUGR
with Doppler changes 4 (5.7%).
Table 6 :
6Distribution of neonates according to
APGAR score at 1, min, (n=200).
APGAR
score at 1
min
Thick,
(n=112)
Moderate,
(n=88)
Total,
(n=200)
N
%
N
%
N
%
<3
5
4.4
0
0
5
2.5
3-5
10
8.9
3
3.4
13
6.5
5-7
31
27.6 25
28.4
56
28
≥7
66
58.9 60
68.2
126
63
Total
112 100 88
100
200
100
Total Apgar score at 1 min for thick meconium was <3 for
5 (4.4%) babies, 3-5 for 10 (8.9%) babies, 5-7 for 31
(27.6%) babies, >7 for 66 (58.9%) babies. Apgar score at
1 min for moderate meconium was 3-5 for 3 (3.4%) babies,
5-7 for 25 (28.4%) babies, >7 for 60 (68.2%) babies.
Table 7 :
7Distribution of patients according to neonatal complications, (n=198).Neonatal
complications
Thick,
(n=110)
Moderate,
(n=88)
Total,
(n=198)
N %
N
%
N
%
Severe birth
asphyxia
5
4.5
0
0
5
2.5
MAS
3
2.7
1
1.1
4
2
HIE
2
1.8
1
1.1
3
1.5
Pulmonary
hemorrhage
1
0.9
0
0
1
0.5
RDS
6
5.4
3
3.5
9
4.5
Septicemia
3
2.7
2
2.3
5
2.5
Total no. of
neonatal
complications
20 18.1
7
7.9
27 13.6
Table 8 :
8Distribution of patients according to
maternal complications, (n=200).
Maternal
complications
Thick,
(n=112)
Moderate,
(n=88)
Total,
(n=200)
N
%
N %
N
%
PPH
1
0.9
2
2.3
3
1.5
Chorio-
amnionitis
1
0.9
0
0
1
0.5
Puerperal
sepsis
0
0
1
1.1
1
0.5
Wound
infection
2
1.8
1
1.1
3
1.5
Maternal
death
0
0
0
0
0
0
Total no. of
maternal
complications
4
3.6
4
4.5
8
4
Women
without
maternal
complications
108 96.4 84 95.4
192 96
Overall, 8 mothers had maternal complications out of
which 3 women had PPH. Another 3 patients had wound
infection post LSCS; one had chorioamnionitis and one
puerperal sepsis. chorioamnionitis, puerperal sepsis,
wound infection patients were managed well with higher
antibiotics. We had no maternal mortality.
DISCUSSION
A hospital based observational, prospective study was
conducted with 200 patients to evaluate maternal and fetal
outcome in MSAF. 112 (56%) patients had thick MSAF
while 88 (44%) patients had moderate MSAF.
Rajput et al having fetal distress 30%, in study of Pushpa et al also fetal distress was most common indication for LSCS 28.5%.9,13 In this study we found 2 fresher still birth babies, so Apgar score of two babies was zero. Total Apgar score at 1 min Pushpa et al shows 22% babies with Apgar score <7 and 78% with >7 at 1 min. This is in concordance to the study of Pushpa et al.13 Pushpa et al prospective comparative study reported Apgar score<7 at 1 min was seen in 22 % cases in the study group.13 In our study the neonatal complications in MSAF were severe birth asphyxia 2.5% with APGAR score at 1 min between 0-3, (it includes two FSB and three NNDs), MAS 2%, septicemia 2.5%, HIE 1.5%, RDS 4.5% and pulmonary hemorrhage 0.5%. In 3 babies who later developed HIE, it was noted that their mothers were transferred patients from peripheral hospital with long standing meconium as the cord was found to be stained with meconium. Patients with thick MSAF had significantly higher incidence of neonatal complications compared to patients with moderate MSAF. Studies of Pushpa et al 6% MAS and 6% severe birth asphyxia13 Rajput et al 6% MAS Priyadharshini et al 40% developed MAS and 14.28% had severe birth asphyxia. 9,12 Present study shows neonatal complications lesser than other studies.Pushpa et al performed trans-cervical intra-partum
amnioinfusion in women of MSAF and found that variable
decelerations were decreased in 68.18% (15/22) cases in
the study group. 13
In our study, 71.5% patients had undergone LSCS, 24%
delivered vaginally and instrumental delivery was
conducted for 4.5% patients. LSCS rate was higher
because of non-availability of fetal scalp blood testing. In
study conducted by Rajput et al most common mode of
delivery was caesarean section (83%) which is similar to
present study. 9 Present study result are higher than to study
conducted by Mundhra et al 49.09% LSCS and 10%
instrumental deliveries. 11
In Unnisa et al 45.7% had LSCS, Normal deliveries were
49.5% and approximately 4.8% cases had instrumental
delivery. 10
We observed that most common indication for LSCS was
fetal distress 44.7%. Other indications were abnormal
labour 20.3, MSAF in early active labour 27.9%, ante
partum hemorrhage 2.8%, IUGR with Doppler changes
3.5% and cord prolapse 0.7%. This finding was consistent
with the studies of for thick meconium was <3 for 5 (4.4%) babies, 3-5 for 10
(8.9%) babies, 5-7 for 31 (27.6%) babies, >7 for 66
(58.9%) babies. Apgar score at 1 min for moderate
meconium was 3-5 for 3 (3.4%) babies, 5-7 for 25 (28.4%)
babies, >7 for 60 (68.1%) babies.
Prognostic value of change in amniotic fluid color during labor. Fetal diagnosis and therapy. A Locatelli, A L Regalia, C Patregnani, M Ratti, L Toso, A Ghidini, 20Locatelli A, Regalia AL, Patregnani C, Ratti M, Toso L, Ghidini A. Prognostic value of change in amniotic fluid color during labor. Fetal diagnosis and therapy. 2005;20(1):5-9.
Meconium in health and in disease. I Antonowicz, H Shwachman, Adv Pediatr. 26Antonowicz I, Shwachman H. Meconium in health and in disease. Adv Pediatr. 1979;26:275-310.
Fetal distress, meconium, and motilin. A Lucas, N D Christofides, T E Adrian, S R Bloom, A Aynsley-Green, Lancet. 3138118718Lucas A, Christofides ND, Adrian TE, Bloom SR, Aynsley-Green A. Fetal distress, meconium, and motilin. Lancet. 1979;313(8118):718.
Meconium aspiration syndrome: intrapartum and neonatal attributes. E M Rossi, E H Philipson, T G Williams, S C Kalhan, Am j obstetr gynecol. 1615Rossi EM, Philipson EH, Williams TG, Kalhan SC. Meconium aspiration syndrome: intrapartum and neonatal attributes. Am j obstetr gynecol. 1989;161(5):1106-10.
Foetal anoxia. J Walker, Int J Obstetr Gynaecol. 612Walker J. Foetal anoxia. Int J Obstetr Gynaecol. 1954;61(2):162-80.
Amniotic fluid meconium: a fetal environmental hazard. K D Ramin, K J Leveno, M A Kelly, T J Carmody, Obstetr Gynecol. 872Ramin KD, Leveno KJ, Kelly MA, Carmody TJ. Amniotic fluid meconium: a fetal environmental hazard. Obstetr Gynecol. 1996;87(2):181-4.
High risk pregnancy. D K James, C P Steer, B Weiner, Gonic, Elsevier1 st editionJames DK, Steer CP, Weiner B. Gonic. High risk pregnancy. 1 st edition, Elsevier. 1994;1135-42.
Effects of massage on pain and anxiety during labour: a randomized controlled trial in Taiwan. M Y Chang, S Y Wang, C H Chen, J advanced nursing. 381Chang MY, Wang SY, Chen CH. Effects of massage on pain and anxiety during labour: a randomized controlled trial in Taiwan. J advanced nursing. 2002;38(1):68-73.
Impact of meconium-stained amniotic fluid on early neonatal outcome. U Rajput, A Jain, J Evolution Med Dental sci. 245Rajput U, Jain A. Impact of meconium-stained amniotic fluid on early neonatal outcome. J Evolution Med Dental sci. 2013;2(45):8788-95.
Maternal and fetal out come in meconium-stained amniotic fluid in a tertiary centre. S Unnisa, B S Sowmya, S B Rao, K Rajagopal, Int J Reprod Contrac Obstetr Gynecol. 53Unnisa S, Sowmya BS, Rao SB, Rajagopal K. Maternal and fetal out come in meconium-stained amniotic fluid in a tertiary centre. Int J Reprod Contrac Obstetr Gynecol. 2016;5(3):813-7.
Fetal outcome in meconiumstained deliveries. R Mundhra, M Agarwal, J clin diagnostic res. 7122874Mundhra R, Agarwal M. Fetal outcome in meconium- stained deliveries. J clin diagnostic res. 2013;7(12):2874.
Meconium-stained liquor and its fetal outcome-retrospective study. M Priyadharshini, S Panicker, IOSR-JDMS. 62Priyadharshini M, Panicker S. Meconium-stained liquor and its fetal outcome-retrospective study. IOSR-JDMS. 2013;6(2):27-31.
Role of intrapartum transcervical amnioinfusion in patients with meconium-stained amniotic fluid. P Bhatia, K Reena, S Nangia, J Obstetr Gynecol India. 631Bhatia P, Reena K, Nangia S. Role of intrapartum transcervical amnioinfusion in patients with meconium-stained amniotic fluid. J Obstetr Gynecol India. 2013;63(1):59-63.
A study of maternal and fetal outcome in meconium-stained amniotic fluid-a prospective hospital-based study. A U Dandale, A K Bava, N R Shinde, Int J Reprod Contracept Obstet Gynecol. 10Cite this article asCite this article as: Dandale AU, Bava AK, Shinde NR. A study of maternal and fetal outcome in meconium-stained amniotic fluid-a prospective hospital-based study. Int J Reprod Contracept Obstet Gynecol 2021;10:4499-507.
| [
-0.06407468020915985,
-0.1511465311050415,
-0.09638307988643646,
0.04218193516135216,
0.03593774139881134,
-0.10333781689405441,
0.017653748393058777,
0.3029571771621704,
0.007543915882706642,
0.05143817141652107,
-0.034673165529966354,
-0.05323951691389084,
0.011352449655532837,
0.2547247... |
Application of Hot Water Extraction Techniques and the Principal Component Analysis to Study the Influence of Cultivation of Commercial Yerba Mate Samples on Their Mineral Profiles
Monize Morgado
Neves
João Batista
Santos Espinelli Junior
Michele Moraes De Souza
Rodolfo Carapelli
Application of Hot Water Extraction Techniques and the Principal Component Analysis to Study the Influence of Cultivation of Commercial Yerba Mate Samples on Their Mineral Profiles
10.1007/s12161-022-02340-0Received: 14 March 2022 / Accepted: 1 June 2022Yerba mate · Organic food · Mineral nutrients · Decoction · Infusion
Consumption of organic food has grown much around the world in the last 20 years. Change in the profile of consumers who have increasingly sought a healthy diet is the major contributor to this phenomenon. In scientific literature, some studies have already shown the nutritional superiority of organic food in the individual evaluation of metabolites. However, few studies have assessed interaction among metabolites, especially the one between minerals and the food matrix. This information may have great relevance in determining the extractability of minerals, especially in food consumed through infusion, such as yerba mate, since this interaction can directly influence their solubility. Thus, this study aimed to use hot water extraction techniques (infusion and decoction) and the principal component analysis (PCA) to evaluate the differences between organic and conventional cultivation systems in absorption and availability of Ca, Mg, Fe, Mn, and Zn in yerba mate leaves and stems. The PCA showed that cultivation influences total mineral contents found in both leaves and stems. Results of extractability only showed differences in conventional leaf samples, from which all minerals under study were better extracted. Results point out a different interaction between minerals and the matrix, depending on the cultivation, and to the stronger interaction between the matrix and minerals in organic samples, a fact which leads to low availability of minerals for consumption.
Introduction
Organic products, which derive from the organic production system, are produced and processed in agreement with international standards of organic agriculture and are usually certified by an independent certificate authority. Essential requirements of organic production are the non-use of organisms and products generated by genetic engineering and replacement of synthetic chemical products, such as pesticides and fertilizers, used for maintaining agricultural production, with sustainable agricultural practices based on ecological principles, whenever possible (Yu et al. 2018).
The IFOAM (International Federation of the Organic Agriculture Movement), an organization that was founded in the 1970s, is in charge of harmonizing standard concepts of organic agriculture and the basis for the regulation of various certifying entities of organic products. There are several organic regulations in the world, both governmental and private ones. In Brazil, the legislation is made up of many laws which permeate several governments and were updated in 2021. Products that comply with the legislation receive an organic product identification seal from the Brazilian Ministry of Agriculture, Livestock and Supply (Muñoz et al. 2016).
Worldwide retail sales of organic products totaled €15 billion in 2000. It reached €106.4 billion in 2019, which means increase of about 600% in the period. The USA was responsible for the movement of €44.7 billion, which represents more than 40% of the global organic market. However, the coronavirus pandemic has caused a profound impact on the organic food industry due to numerous factors, such as changes in consumers' eating habits in pursuit of personal health and wellness. Thereby, a rapid increase in the organic market is expected all over the world, mainly in developing countries, such as Brazil, as the result of the development of regional markets, which was also accelerated by the coronavirus crisis (Willer et al. 2021).
Changes in eating habits related to concern for health are usually associated with consumers' perception of the nutritional superiority of a certain type of food. Regarding organic food, this perception can be linked mainly to the following issues: (1) more beneficial nutrition components in organic food, such as vitamins, polyunsaturated fatty acids, and antioxidants and (2) lower levels of heavy metals, fungal toxins and pesticide residues in organic food (Niggli, 2009). It was corroborated by Yu et al. (2018) in a recent review article. According to the authors, in general, organic food have several beneficial properties, such as antioxidant and anti-cancer activities, related to compositional characteristics, such as the profile of phenolic compounds. In addition, they exhibit high levels of high-quality proteins and polyunsaturated fatty acids in bovine meat, besides low levels of nitrate and heavy metals in fruit and vegetables and no pesticide residues (Yu et al. 2018).
Although there are some studies in the literature that compare different aspects of nutritional profiles of organic and conventional food (Vigar et al. 2020), few have addressed the influence that their management exerts on the correlation among components of the food matrix, mainly minerals and metabolites. This type of study becomes significant when food under study is consumed through aqueous extracts, such as coffee, tea, and yerba mate since the interaction between minerals and the matrix may influence their solubility and, therefore, their availability in the diet. It is known that a balanced diet needs to supply all essential minerals required by the body. Minerals play key roles in the human body, from building strong bones (Ca, Mg, Mn, and others) to constituting enzymes (Cu, Fe, Mn, Mg, and others) and functioning in nerve cells (K and others) (Gharibzahedi & Jafari 2017).
Yerba mate (Ilex paraguariensis St. Hil) is a forest tree native to South America which is consumed as a tea-like beverage in many Latin American countries, such as Argentina, Paraguay, Brazil, and Uruguay. The main consumers are Brazil and Uruguay (Bastos et al. 2018;Pardinho et al. 2018;Rocha et al. 2017). Consumption of yerba mate products has recently expanded to different countries, such as Australia, France, Germany, Italy, Japan, Korea, Russia, Spain, Syria, and the USA (Cardozo Junior, Morand 2016). Regarding its cultivation, yerba mate is a culture that has its leaves and stems removed regularly, which implies massive export of nutrients and requires nutritional replacement to maintain productivity (Gaiad, Lopes 1986). Nevertheless, organic brands have been easily found in markets nowadays.
The mineral content of yerba mate has been extensively studied by the scientific literature over the years with different approaches. Not only total concentration and hot water extraction (Pandolfo et al. 2003;) and in vitro bioaccessibility of micronutrients and inorganic contaminants (Schmite et al. 2019) but also the influence of agronomic variables on the mineral profile have been reported (Barbosa et al. 2015(Barbosa et al. , 2018Reissmann et al. 1999). However, although the influence of agronomic variables has already been considered, the impact of the set of standards regulated by organic legislations on the mineral profile and on its extractability has not yet been evaluated.
Hot water extraction techniques have been applied to study the extraction of components of various herbs consumed through solution. Infusion and decoction are methods that have often been cited by this type of study (Grzesik et al. 2008;Ozcan et al. 2008;Kaneria et al. 2011). There are some studies that compare the efficiency of both techniques; regarding minerals, decoction usually exhibits better extraction efficiency (Pereira Junior et al. 2016;Randjelovic et al. 2013). The difference in the contact between the extractor and the sample may be a determining factor in results since the more intense contact that occurs in decoction could lead to extraction of compounds that are more strongly bound to the matrix while, in infusion, only minerals of lesser interaction would be extracted (Dias et al. 2015). Therefore, these techniques could be useful tools to understand the interaction between minerals and the food matrix, particularly with the aid of chemometric tools, such as the principal component analysis (PCA).
Thus, this study aims at investigating the influence of techniques standardized by the Brazilian legislation of organics on the mineral profile of commercial samples of yerba mate and at evaluating the use of different hot water extraction techniques combined with the PCA to understand this influence on macro and micronutrient interaction with the matrix and extractability.
Material and Methods
Samples
Samples of green yerba mate were randomly purchased in a market in the Rio Grande, Rio Grande do Sul (RS) state, Brazil, and on sales websites, totaling 12 samples (7 of conventional origin and 5 of organic origin). All samples were from southern Brazil and were within the validity period specified by the supplier. They were composed of leaves and stems in the ratio of 70:30, respectively, except for one made for export that was only composed of leaves. All organic samples were certified by the Brazilian Ministry of Agriculture, Livestock, and Supply.
Instrumentation
Determinations of Fe, Mg, Mn, and Zn were performed by flame atomic absorption spectrometry (FAAS). Calcium (Ca) and K were determined by flame atomic emission spectrometry (FAES). All determinations were performed by a Perkin Elmer Analyst-800 atomic spectrometer equipped with a 10-cm air-acetylene burner head and a single element hallow-cathode lamp was used for all measurements. Selected spectral lines (nm) of all metals were as follows: Ca 422.7, Fe 248.3, K 766.5, Mg 285.2, Mn 279.5, and Zn 213.9. Deuterium lamp background correction was employed to correct for the non-specific absorbance. Analytical parameters of determinations were limit of detection and limit of quantification (Ca = 0.34 mg L −1 and 1.00 mg L −1 ; Fe = 0.23 mg L −1 and 0.70 mg L −1 ; K = 0.03 mg L −1 and 0.09 mg L −1 ; Mg = 0.02 mg L −1 and 0.05 mg L −1 ; Mn = 0.04 mg L −1 and 0.12 mg L −1 ; Zn = 0.06 mg L −1 and 0.19 mg L −1 ); linear range (Ca = 1.00-3.00 mg L −1 ; Fe = 0.75-6.00 mg L −1 ; K = 0.10 − 1.50 mg L −1 ; Mg = 0.06-0.30 mg L −1 ; Mn = 0.15-1.50 mg L −1 ; Zn = 0.20-0.75 mg L −1 ).
Reagents and Analytical Solutions
All glassware and polypropylene flasks were washed with soap, soaked in 10% v v −1 HNO 3 for 24 h, and rinsed with deionized water prior to use. Analytical grade reagents and milli-Q water (Millipore, Bedford, MA, USA) were employed. All stock standard solutions used to prepare element standard solutions were certified with AAS grade (SpecSol, Brazil). Working standard solutions were prepared daily by diluting appropriate aliquots of the stock solution in Milli-Q water. Nitric acid (65% m v −1 ) was purchased from Vetec (Brazil). Perchloric acid (37%) was purchased from Dinamica (Brazil).
Stems and leaves were manually separated, portions were weighed and the finest part was sifted through a sieve whose mesh size was 0.2 mm. Stems were manually collected with the use of plastic tweezers, ground by a blender with stainless steel blades, and sifted through a sieve whose mesh size was 0.2 mm. After separation, both leaves and stems in each sample were ground, sifted through a 32-mesh sieve, oven-dried with forced air circulation at 40 °C until constant weight, stored individually, and identified in polyethylene bottles for later analyses.
Sample Preparation
Total Mineral Determination
The sample decomposition method was performed in agreement with recommendations issued by the Brazilian Agricultural Research Corporation (EMBRAPA). It consisted of two steps in a heating program by a block digester. The mixture consisted of a 200-mg sample (leaf or stem), 2.5 mL HNO 3 :HClO 4 (2:1 (vv −1 )), and 1.0 mL ultrapure water. After the 4-h pre-decomposition step at room temperature, the mixture was slowly heated until 120 °C, which was kept until NO 2 release (brown vapor) ceased completely. Then, the temperature was slowly raised to 210 °C and kept for 25 min. After the solution cooled down, it was diluted to the final volume of 50.0 mL with ultrapure water (Nogueira et al. 2005).
Hot Water Extraction
Infusion Fifty milliliters of ultrapure water heated to 100 °C was poured over a 1-g sample, homogenized for 1 min, and kept in contact for 15 min. During the extraction time, the temperature of the solution gradually returned to room temperature. Samples were centrifuged at 17,920 × G for 3 min and the supernatant was filtered (average pore size of 8 um). Finally, extracts were diluted with ultrapure water to 100 mL, stored in polyethylene bottles, and kept under refrigeration for further analysis in FAAS and FAES.
Decoction 50 ml ultrapure water heated to 100 °C was poured over 1 g sample in a glass beaker and placed on a heating plate. The mixture was boiled for 15 min, and then, the sample was centrifuged at 17,920 × g for 3 min. Volume variations due to evaporation were not considered. The supernatant was filtered (average pore size of 8 um), diluted with ultrapure water to 100 mL, stored in polyethylene bottles, and kept under refrigeration for further analysis in FAAS and FAES.
Aqueous extracts resulting from infusion and decoction were all directly injected into the equipment nebulization system without any treatment. All measurements were performed in triplicate.
Exploratory Analyses
Data matrices composed of rows with yerba mate leaf and/ or stem samples and analyte concentrations in columns were organized and the PCA was carried out by the Scilab 6.0.1 software (GNU General Public License 2.0), in agreement with Ferreira et al. (1999). Data were auto-scaled due to different orders of magnitude among variables.
The results of total content and extractability were submitted to analysis of variance (ANOVA) and the means compared by the Tukey test (p < 0.05) with the aid of statistical software 5.0.
Accuracy
To evaluate the accuracy of the digestion procedure, peach leaves certified reference material (NIST 1547) was analyzed. Moreover, to evaluate the matrix effect on all determinations, addiction and recovery tests were performed. Final concentrations added to each element in addiction and recovery tests were as follows: Ca (1.50 mg L −1 for digestion and 0.25 mg L −1 for extraction), Fe (1.00 mg L −1 for digestion and extraction), K (0.25 mg L −1 for digestion and 0.50 mg L −1 for extraction), Mg (0.10 mg L −1 for digestion and extraction), Mn (1.00 mg L −1 for digestion and extraction), and Zn (0.25 mg L −1 for digestion and extraction).
Results and Discussion
Accuracy
The accuracy of determinations of Fe, Mn, Mg, Zn, Ca, and K was estimated for their total values. Agreement for determination of total contents of Fe, Mn, Mg, Zn, Ca, and K in the acid digestion solution of the certified reference material (NIST 1547, peach leaves) ranged from 85.2 to 105.9%. Addiction and recovery tests were also performed. Results ranged from 94.7 to 119.0% in leaves and from 82.0 to 116.5% in stems.
Concerning aqueous extracts, addiction, and recovery tests were carried out for both infusion and decoction. Results of infusion of leaves and stems ranged from 80.1 to 114.8% and from 81.8 to 102.2%, respectively. Results of decoction of leaves and stems ranged from 80.1 to 118.7% and from 84.1 to 112.2%, respectively.
Principal Component Analysis (PCA)
To evaluate the mineral profile of yerba mate (leaves and stems), FAAS and FAES analysis of sample solutions provided by acid decomposition (Table 1), infusion and decoction extraction were performed. To avoid that certain factors, such as variation in concentrations of minerals in the soil, could affect results, the ones of mineral extractability were expressed as relative values of total concentrations (percentages of extractability) ( Table 2).
PCA and ANOVA were applied to the results. Comparison between trials shows general agreement. However, some observations made in the PCA are not clear in the ANOVA test, mainly due to the high dispersion of groups around the mean value, as can be observed, for example, by Mn in total contents of leaves. The PCA showed that the analyte characterizes organic samples; however, despite visualizing this behavior in the average of organic and conventional groups, no statistical difference could be found between them. This result is not surprising since PCA reduces the dimensionality of the dataset while retaining most of its variation, allowing to group samples and visualize characteristics that sometimes do not emerge univariately (Ringnér, 2016). Thus, the PCA is a very interesting tool for this exploratory study.
Total Concentration
First, the PCA was carried out to visualize all resulting data on the total concentration of minerals. Results are shown in Fig. 1a scores and 1b loadings. The PCA demonstrated that a small number of variables dominate total data variability since the two first principal components account for 80% of the total variability. The first component was responsible for 62% while the second accounted for 18% of total information. Considering the parts of plants in PC1 and PC2 plots, two visual clusters appeared. All data on leaf samples were located at negative PC1 scores (squares), well separated from stem samples, which had positive PC1 scores (circles). The profile of PC1 loadings exhibits negative values in all descriptors, thus characterizing leaf samples. It is well known that mineral elements are extracted from the soil by roots, cross it via apoplastic (extracellular) and/or symplastic (intracellular) pathways until the xylem; so, they are delivered to transpiring leaf tissues, where they are stored or remobilized by phloem, depending on their mobility characteristics (White & Brown 2010). With respect to cultivation, a well-defined separation between conventional (black circles and squares) and organic (white circles and squares) ones could not be observed. The first PCA clearly shows that leaves and stems have different characteristics regarding the mineral profile. Therefore, to better understand the results, a second study was carried out to analyze leaves and stems separately. Firstly, data on leaf samples (squares) were used to perform a new classification by the PCA. The two first components accounted for 61% of total data variability. The first and second components were responsible for 34% and 27% of total information, respectively. Figure 2a and b show score and loading scatter plots of PC1 and PC2.
The analysis of cultivation classes suggested the existence of two groups based on the distribution of samples along PC1. Conventional samples (black squares) had negative PC1 scores while organic ones (white squares) had positive PC1 scores. The profile of PC1 loadings exhibits negative values for Ca, K, Mg, and Zn (conventional sample descriptors) and positive values for Mn and Fe (organic sample descriptors).
When stem samples (circles) were analyzed, the two first components accounted for 76% of total data variability. The first and second components were responsible for 44% and 32% of total information, respectively. Again, two groups were observed along PC1. Conventional samples (black circles) had negative PC1 scores and organic samples (white circles) were located around the positive quadrant of PC1 and the negative quadrant of PC2. The loading profile shows negative values of PC1 for K (conventional sample descriptors), positive value of PC1 and negative of PC2 for Mn and The first observation that should be highlighted is the high concentration of Fe and Mn in both stems and leaves in organic samples. Contributors could be related to some practices, such as soil management and organic fertilization in organic cultivation, that lead to an increment in organic acid concentration in the soil. Organic compounds, through the chelation process, increase Fe and Mn solubility and, consequently, their availability for absorption by plants (Hue, Vega & Silva 2001, Worthington 2001. Moreover, high organic matter concentration could lead to a reducing environment which also increases the availability of these elements (Hue et al. 2001, Pandey 2015.
Potassium had the opposite behavior of Mn and Fe since higher concentration was found in leaves and stems in conventional samples. The most likely explanation for this observation is related to the use of potassium-based fertilizer, commonly employed by the conventional cultivation system, which leads to the high availability of this element for plant absorption (Worthington 2001). Besides, the great mobility of K in the plant system justified its similar behavior in leaf and stem samples.
High concentrations of Ca, Mg, and Zn were found in conventional leaf samples, but no difference could be found between cultivation and stem samples. Ca is a highly immobile mineral in plants, i.e., once deposited in leaves, it becomes virtually unavailable for remobilization. As a result, plants need a continuous supply of these elements for new organs (Loneragan et al. 1976). Wherefore, the results of this study suggest that Ca found in stems does not come from relocation but from continuous uptake from the soil, which has not been influenced by any cultivation process. On the other hand, conventional leaves exhibited higher concentrations of Ca than organic ones. An explanation could be related to the high concentration of organic matter in the soil in organic cultivation, including previously discussed organic acids, that could increase soil-Ca affinity, consequently making it less available to plant absorption and enabling a smaller amount of this nutrient to reach leaves.
Magnesium tends to accumulate in transpiring organs, such as leaves (Merhaut 2007). A significant part is bounded to chlorophyll or insoluble species, such as malate and citrate; however, the largest fraction is in the inorganic form, highly mobile, that is redistributed to other parts of the plant. Therefore, results show that, since there is no magnesium deficiency in the cultivation system and its quantity for remobilization is enough to supply the stem demand, the cultivation system did not exert much influence. On the contrary, the results of leaves show high content of this element in conventional samples. Magnesium absorption is largely influenced by the competitive effect of other minerals. The main interfering elements are K + > NH 4 + > Ca 2+ > Na + ; however, Mn, in divalent form, when at elevated concentrations, can also compete with Mg for retention sites in soil or plant membranes (Merhaut 2007). Quartin et al. (2001) corroborate this information since they reported that an increase in manganese (Mn) accumulation in triticale leaves led to a significant decrease in Mg contents. Thus, the results of this study show that a possible determinant factor of high Mg contents in conventional leaves is the low Mn content absorbed by conventional samples, a fact that may be confirmed by the results of both stems and leaves described in Table 1.
In soils richly supplied with Zn, this element is highly mobile and broadly remobilized to the meristematic region of the plant (Loneragan et al. 1976). Therefore, similar to Mg, demand for Zn in stem samples seems to be supplied by its remobilization, without the great influence of the cultivation process. However, differences found in analyses of leaf samples show higher content of Zn in conventional leaves, probably due to its high affinity for sites of organic matter, which is found in high quantity in organic soils. Results discussed so far concern levels of minerals absorbed by plants. However, they neither enable to infer how minerals are linked to leaves and stems nor provide information about their extractability and availability for ingestion (Fig. 3).
Mineral Extractability
As clearly shown by the analysis of total contents, the behavior of leaves and stems regarding the accumulation of nutrients is different. Therefore, the PCA of extractability results was done separately for leaves and stems. However, score plots were classified both by cultivation (organic and conventional) and by the extraction method (infusion and decoction) simultaneously.
In the analysis of leaf samples (squares), the first three components accounted for 85% of total data variability. The first component was responsible for 41%, the second, for 25%, and the third, for 19% of total information. Since the second and third components exhibit similar data variability, the three components were evaluated by the study. Although both PC1 and PC2 and PC1 and PC3 score plots show good separation related to the variable cultivation, the PC1 and PC3 score plots exhibit better separation regarding extraction methods. Thus, it was shown by this study. Figure 4a and b shows score and loading scatter plots of PC1 and PC3.
The analysis of cultivation classes suggested the existence of two groups based on the distribution of samples by cultivation along PC1. In addition, separation by extraction methods along PC3 may be observed. The infusion group is represented by white (organic samples) and black (conventional samples) squares while the decoction group is represented by light gray (organic samples) and dark gray (conventional samples) squares. Figure 4b shows that all descriptors of loading plots are in the negative quadrant of PC1; therefore, they characterize conventional cultivation samples. Besides, Fe and K were found to be better extracted by the infusion method while Ca, Mg, Mn, and Zn were better extracted by the decoction method. Results suggest that all minerals under study are more strongly bound to the matrix in organic samples; therefore, less extracted by the applied methods. Moreover, since decoction is a more aggressive extraction method, it seems that, in conventional samples, extractable fractions of Ca, Mg, Mn, and Zn are more strongly bound to the matrix than Fe and K.
Firstly, it should be highlighted that, although Mn and Fe are found at higher concentrations in organic samples, they are more easily extracted from conventional samples. Fe is the least extracted element by the applied methods, as shown in Table 2. However, the behavior observed in the PCA, i.e., that Fe is more effectively extracted by the infusion method, may indicate that its extractable fraction is stored in soluble species and that exposure to high temperature in the decoction method seems to decrease extractability. An explanation for this observation is that storage of soluble iron as inorganic species and more abrupt conditions to which samples are subjected in decoction can make these species react with insoluble matrix concomitants. Phenolic compounds are a viable hypothesis, firstly because they have an affinity for metal complexation (Hynes, O'Coinceanainn 2004). Secondly, classes of insoluble phenolic compounds (conjugated and bounded) could justify a reduction in Fe extractability (Hynes, O'Coinceanainn 2004). Finally, organic samples usually have high quantity of phenolic compounds, as means of defense, because organic cultivation does not use pesticides. All these facts may be the reasons for low Fe extraction from organic samples, indicating that, in organic samples, high phenolic content may be an important factor in the low solubility of Fe. Another possibility is reduction in solubility due to oxidation of inorganic Fe in the decoction process. Potassium, predominantly found as an inorganic soluble species, may have a similar explanation to Fe but, in decoction, it may have been precipitated by adsorption by other compounds.
Results of Ca, Mg, and Mn may be related to biomineralization processes performed by plants. The formation of oxalate crystals of Ca, Mg, and Mn in leaf tissues has already been reported by the literature. He et al. (2012), for example, reported the formation of oxalate crystals of Ca, Mg, Sr, and Ba in Acacia species. Pongrac et al. (2020) pointed out the formation of oxalate crystals of Ca and Mn in sample of tea leaves (Camellia sinensis (L.) Kuntze). In yerba mate leaves, crystals have also been reported. Barbosa et al. (2019) stated that the formation of calcium oxalate crystals is the most likely explanation for crystals found in yerba mate leaves, even though they highlighted the need for further experiments to confirm it (Barbosa et al. 2019). The biomineralization process may have different functions for each element investigated by this study. In the case of Mn, it would probably be related to detoxification due to its high absorption, mainly in organic samples. For Ca and Mg, it could be a set of factors, such as mechanical support and protection against herbivores; the latter is very relevant to this study since it may explain the low extractability of these elements in organic samples. Finally, the low solubility of oxalate salts may be the reason for the great extractability of these elements by the decoction process.
There are several ways in which plants accumulate zinc. Some examples are complexes coordinated with organic acids, such as oxalic, citric and malic ones, zinc crystals with high sulfur or phosphorus contents and glutathione, phytochelatins, or metallothioneins-linked zinc compounds (Gupta et al. 2016;Dinh et al. 2015). Although the influence of cultivation may be observed in the assimilation of this element through the PCA, unlike the other elements analyzed by this study, no hypothesis can be raised from the results.
Finally, in the PCA of stem samples, the first three components accounted for 80% of total data variability. The first component was responsible for 39%, the second, for 24%, and the third, for 17% of total information. The formation of groups related to cultivation and type of extraction could not be observed by the analyses considering PC1and PC2, PC1 and PC3, or PC2 and PC3 (results not shown). Results may be evidence of the fact that differences in metabolism of elements resulting from differences in cultivation are more evident in storage organs, such as leaves. It may be due to the supply of nutrients to stem from remobilization processes from storage organs.
Conclusion
Differences between mineral profiles of organic and conventional yerba mate could be found. Leaf samples exhibited higher concentrations of all elements than stem ones. Mn and Fe characterized all organic samples while potassium characterized all conventional samples. Ca, Mg, and Zn characterize conventional leaves, but no differences related to cultivation could be found in stem samples. Remobilization of nutrients seems to be an important issue to understand the results, mainly the ones of stem samples. It may be inferred that organic matter of the soil is an important factor in the absorption of minerals, influencing the absorption of Fe and Mn positively and Ca and Zn, negatively. Competition among nutrients was determinant for Mg contents while Mn was the most significant competitor in samples under study. The use of fertilizers may be the determining factor for the behavior of K. It should be emphasized that observations made by this study were carried out in commercial samples with no control of variables; therefore, they reflect the influence of rules controlled by the Brazilian legislation for production of organic food on final products sold in the market.
Regarding results of hot water extraction, elements under study were found to be less extractable from samples of organic leaves, thus, indicating a greater connection with the matrix in this group. Fe and K are more extracted by the infusion technique, showing that exposure to agitation and temperature in decoction leads to their precipitation process. On the other hand, Mg, Mn, Ca, and Zn are more extractable by the decoction technique. The formation of oxalate crystals is a hypothesis for the behavior of the first three elements. In the case of Zn, despite showing similar behavior, no hypothesis could be formulated. In stem samples, no difference was found between organic and conventional groups. It corroborates what was previously described about the nutrient supply in stems being influenced by remobilization processes.
Finally, the application of the PCA to results of both analyses of total and hot water extraction showed the potential of preliminary studies of the influence of agricultural practices on freely traded food. However, based on these results, it is necessary to propose fractionation studies or more specific speciation to deepen knowledge in this area.
Fig. 1
1PC1 and PC2 a scores and b loading plots of all yerba mate samples, showing a comparison of part of the plant and cultivation. Stems (squares), leaves (circles), conventional cultivation (black circles and squares), organic cultivation (white circle and squares) Fe (organic sample descriptors), and positive values of PC1 and PC2 for Ca, Mg, and Zn (both group descriptors).
Fig. 2
2PC1 and PC2 a scores and b loading plots of yerba mate leaf samples, showing a comparison of cultivation. Conventional cultivation (black squares), organic cultivation (white squares)
Fig. 3
3PC1 and PC2 a scores and b loading plots of yerba mate stem samples, showing a comparison of cultivation. Conventional cultivation (black circles), organic cultivation (white circles) Fig. 4 PC1 and PC3 a scores and b loading plots of yerba mate leaf samples, showing a comparison of cultivation. Conventional sample infusion (black squares), organic sample infusion (white squares), conventional sample decoction (dark gray squares), organic sample decoction (light gray squares)
Table 1
1Ca, Fe, K, Mn, and Zn average total contents (mg kg. −1 ) in organic and conventional samples of yerba mate leaves and stems * Values represent mean concentration for each group of samples ± standard deviation ** Equal letters in the same line symbolize similarity at the 95% significance level while different letters symbolize difference at the 95% significance levelElement
Conventional
Organic
Leaf
Branch
Leaf
Branch
Fe
279 c ± 54
101 a ± 45
337 d ± 85
151 b ± 40
Zn
64 a ± 18
54 a ± 15
54 a ± 15
52 a ± 17
Mn
2118 c ± 322
871 a ± 196
2281 c ± 753
1295 b ± 190
K
20,096 b ± 2391
14,734 a ± 1553
16,224 a ± 238
13,701 a ± 488
Mg
5877 b ± 937
2862 a ± 1059
5496 b ± 627
3655 a ± 775
Ca
6825 b ± 600
6925 b ± 635
5545 a ± 1217
4839 a ± 912
Table 2
2Ca, Fe, K, Mn, and Zn average aqueous extractability (%) in organic and conventional samples of yerba mate leaves and stems extracted by infusion and decoction * Values represent mean extractability for each group of samples ± standard deviation ** Equal lowercase letters in the same line, for each element, symbolize similarity at the 95% significance level while different lowercase letters symbolize difference at the 95% significance level *** Equal uppercase letters in the same column, for each element, symbolize similarity at the 95% significance level while different uppercase letters symbolize difference at the 95% significance levelElement
Extraction
Conventional
Organic
Leaf
Stem
Leaf
Stem
Fe
Decoction
1.4 a,A ± 0.7
3.0 a,A ± 1.4
0.8 a,A ± 0.3
1.2 a,A ± 0.3
Infusion
2.3 a,B ± 0.6
3.8 b,A ± 1.3
0.9 a,A ± 0.3
1.3 a,A ± 0.3
Zn
Decoction
40.0 b,A ± 11.2
25.2 a,A ± 6.7
21.3 a,A ± 6.0
19.0 a,A ± 5.8
Infusion
13.5 a,B ± 2.4
9.6 a,B ± 3.0
14.0 a,B ± 5.0
9.0 a,B ± 3.0
Mn
Decoction
58.3 b,A ± 5.4
51.4 b,A ± 8.8
31.2 a.A ± 5.0
48.2 b,A ± 4.7
Infusion
56.0 a,A ± 4.8
55.0 a,A ± 8.8
45.9 a,B ± 9.2
57.1 a,A ± 10.8
K
Decoction
78.3 b,A ± 14.7
76.6 b,A ± 13.0
87.7 b,A ± 11.0
58.7 a,A ± 10.1
Infusion
80.5 a,A ± 10.2
78.1 a,A ± 8.8
69.2 a,B ± 7.4
71.5 a,A ± 10.8
Mg
Decoction
25.2 a,A ± 19.4
17.5 a,A ± 7.5
24.8 a,A ± 3.4
20.2 a,A ± 1.7
Infusion
19.4 a,A ± 3.9
18.1 a,A ± 7.6
21.2 a,A ± 5.0
19.5 a,A ± 2.6
Ca
Decoction
37.5 b,A ± 6.6
15.1 a,A ± 3.4
14.2 a,A ± 2.2
12.3 a,A ± 1.3
Infusion
25.6 c,B ± 3.4
21.7 b,A ± 3.0
14.5 a,A ± 0.4
14.9 a,A ± 2.0
AcknowledgementsThe authors are grateful to the Fundação de Amp-
Productivity, profitability and partial nutrient balance in maized-based conventional and organic farming systems in Kenya. N Adamtey, M W Musyoka, C Zundel, J G Cobo, E Karanja, Kkm Fiaboe, A Muriuki, M Mucheru-Muna, B Vanlauwe, E Berset, M M Messmer, A Gattinger, G S Bhula, G Cadish, A Fliessbach, P Mäder, U Niggli, D Foster, 10.1016/j.agee.2016.10.001Agr Ecosyst Environ. 235Adamtey N, Musyoka MW, Zundel C, Cobo JG, Karanja E, Fiaboe KKM, Muriuki A, Mucheru-Muna M, Vanlauwe B, Berset E, Messmer MM, Gattinger A, Bhula GS, Cadish G, Fliessbach A, Mäder P, Niggli U, Foster D (2016) Productivity, profitabil- ity and partial nutrient balance in maized-based conventional and organic farming systems in Kenya. Agr Ecosyst Environ 235:61-79. https:// doi. org/ 10. 1016/j. agee. 2016. 10. 001
Plant growth, nutrients and potentially toxic elements in leaves of yerba mate clones in response to phosphorus in acid soils. J Z Barbosa, Acv Motta, R Consalter, G C Poggere, D Santin, I Wendling, 10.1590/0001-37652018201607011590/ 0001-37652 01820 160701Agrar Sci. 90Barbosa JZ, Motta ACV, Consalter R, Poggere GC, Santin D, Wend- ling I (2018) Plant growth, nutrients and potentially toxic ele- ments in leaves of yerba mate clones in response to phosphorus in acid soils. Agrar Sci 90:557-571. https:// doi. org/ 10. 1590/ 0001-37652 01820 160701
Spatial distribution of strutctural elements in leaves of Ilex paraguariensis: physiological and ecological implictations. J Z Barbosa, Acv Motta, A R Reis, R S Correa, S A Prior, 10.1007/s00468-019-01900-yTrees. 34Barbosa JZ, Motta ACV, Reis AR, Correa RS, Prior SA (2019) Spa- tial distribution of strutctural elements in leaves of Ilex para- guariensis: physiological and ecological implictations. Trees 34:101-110. https:// doi. org/ 10. 1007/ s00468-019-01900-y
Composition, hot-water solubility of elements and nutritional value of fruits and leaves of yerba mate. J Z Barbosa, L M Zambon, Acv Motta, I Wndling, 10.1590/S1413-705420150006000061590/ S1413-70542 01500 06000 06Food Sci Technol. 39Barbosa JZ, Zambon LM, Motta ACV, Wndling I (2015) Composi- tion, hot-water solubility of elements and nutritional value of fruits and leaves of yerba mate. Food Sci Technol 39:593-603. https:// doi. org/ 10. 1590/ S1413-70542 01500 06000 06
Yerba Mate: nutrient levels and quality of the beverage depending on the harvest season. M C Bastos, V F Cherobim, C B Reissman, J F Kaseker, S Gaiad, 10.1016/j.jfca.2018.01.01901. 019J Food Compos Anal. 69Bastos MC, Cherobim VF, Reissman CB, Kaseker JF, Gaiad S (2018) Yerba Mate: nutrient levels and quality of the beverage depend- ing on the harvest season. J Food Compos Anal 69:1-6. https:// doi. org/ 10. 1016/j. jfca. 2018. 01. 019
Interest of mate (Ilex paraguariensis A. St.-Hil.) as a new natural functional food to preserve human cardiovascular health-a review. E L Cardozo Junior, C Morand, 10.1016/j.jff.2015.12.010J Funct Foods. 21Cardozo Junior EL, Morand C (2016) Interest of mate (Ilex paraguar- iensis A. St.-Hil.) as a new natural functional food to preserve human cardiovascular health-a review. J Funct Foods 21:440- 454. https:// doi. org/ 10. 1016/j. jff. 2015. 12. 010
Nutritional Quality o organic foods: a systematic review. A D Dangour, S K Dodhia, A Hayter, Allen E Lock, K Uauy, R , 10.3945/ajcn.2009.28041Am J Clin Nutr. 90Dangour AD, Dodhia SK, Hayter A, Allen E, Lock K, Uauy R (2009) Nutritional Quality o organic foods: a systematic review. Am J Clin Nutr 90:680-685. https:// doi. org/ 10. 3945/ ajcn. 2009. 28041
Nutritional parameters of infusions and decoctions obtained from Fragariavesca L. roots and vegetative parts. M I Dias, L Barros, P Morales, M C Sánchez-Mata, Mbpp Oliveira, Icfr Ferreira, 10.1016/j.lwt.2015.01.034LWT-Food Sci Technol. 62Dias MI, Barros L, Morales P, Sánchez-Mata MC, Oliveira MBPP, Ferreira ICFR (2015) Nutritional parameters of infusions and decoctions obtained from Fragariavesca L. roots and vegeta- tive parts. LWT-Food Sci Technol 62:32-38. https:// doi. org/ 10. 1016/j. lwt. 2015. 01. 034
Accumulation and distribution of zinc in the leaves and roots of the hyperaccumulator Noccaea caerulescens. N T Dinh, D T Vu, D Mulligan, A V Nguyen, 10.1016/j.envexpbot.2014.10.001Environ Exp Bot. 110Dinh NT, Vu DT, Mulligan D, Nguyen AV (2015) Accumulation and distribution of zinc in the leaves and roots of the hyperac- cumulator Noccaea caerulescens. Environ Exp Bot 110:85-95. https:// doi. org/ 10. 1016/j. envex pbot. 2014. 10. 001
Integrated analyses of phenolic compounds and minerals of brazilian organic and conventional grape juices and wines: validation of a method for determination of Cu, Fe and Mn. Mcp Dutra, L L Rodrigues, D Oliveira, G E Pereira, M S Lima, 10.1016/j.foodchem.2018.07.01407. 014Food Chem. 269Dutra MCP, Rodrigues LL, Oliveira D, Pereira GE, Lima MS (2018) Integrated analyses of phenolic compounds and minerals of bra- zilian organic and conventional grape juices and wines: valida- tion of a method for determination of Cu, Fe and Mn. Food Chem 269:157-165. https:// doi. org/ 10. 1016/j. foodc hem. 2018. 07. 014
EEA Report no. 11/2005 -Household consumption and the environment. European Environment Agency. 3Copenhagen: EEAEuropean Environment Agency (2005). EEA Report no. 11/2005 - Household consumption and the environment. Copenhagen: EEA, (Chapter 3).
Chemometrics I: multivariate calibration, a tutorial. Mmc Ferreira, A M Antunes, M S Melgo, Plo Volpe, 10.1590/S0100-404219990005000161590/ S0100-40421 99900 05000 16Quim Nova. 22Ferreira MMC, Antunes AM, Melgo MS, Volpe PLO (1999) Chemo- metrics I: multivariate calibration, a tutorial. Quim Nova 22:724- 731. https:// doi. org/ 10. 1590/ S0100-40421 99900 05000 16
Ocorrência de micorriza vesicular-arbuscular em Erva-mate (Ilex paraguariensis St. Hil.). S Gaiad, E S Lopes, Boletim De Pesquisa Florestal. 12Gaiad S, Lopes ES (1986) Ocorrência de micorriza vesicular-arbus- cular em Erva-mate (Ilex paraguariensis St. Hil.). Boletim De Pesquisa Florestal 12:21-29
The importance of minerals in human nutrition: Bioavailability, food fortification, processing effects and nanoencapsulation. Smt Gharibzahedi, S M Jafari, 10.1016/j.tifs.2017.02.017Trends Food Sci Technol. 62Gharibzahedi SMT, Jafari SM (2017) The importance of minerals in human nutrition: Bioavailability, food fortification, processing effects and nanoencapsulation. Trends Food Sci Technol 62:119- 132. https:// doi. org/ 10. 1016/j. tifs. 2017. 02. 017
Leaching of cadmium and lead from dried fruits and fruits teas to infusionons and decoctions. E B Grzesik, A J Kolon, 10.1016/j.jfca.2007.11.008J Food Compos Anal. 21Grzesik EB, Kolon AJ (2008) Leaching of cadmium and lead from dried fruits and fruits teas to infusionons and decoctions. J Food Compos Anal 21:326-331. https:// doi. org/ 10. 1016/j. jfca. 2007. 11. 008
Mechanism of Zinc absorption in plants: uptake, transport, translocation and accumulation. N Gupta, H Ram, B Kumar, 10.1007/s11157-016-9390-1Rev Environ Sci Bio/technol. 15Gupta N, Ram H, Kumar B (2016) Mechanism of Zinc absorption in plants: uptake, transport, translocation and accumulation. Rev Environ Sci Bio/technol 15:89-109. https:// doi. org/ 10. 1007/ s11157-016-9390-1
Precipitation of calcium, magnesium, strontium and barium in tissues of four Acacia species (Leguminosae: Mimosoideae). H He, T M Bleby, E J Veneklaas, H Lambers, J Kuo, 10.1371/journal.pone.0041563PLoS ONE. 763He H, Bleby TM, Veneklaas EJ, Lambers H, Kuo J (2012) Precipita- tion of calcium, magnesium, strontium and barium in tissues of four Acacia species (Leguminosae: Mimosoideae). PLoS ONE 7:e41563. https:// doi. org/ 10. 1371/ journ al. pone. 00415 63
Manganese toxicity in Hawaiian oxisol affected by soil pH and organic amendments. N V Hue, J A Vegas, 10.2136/sssaj2001.651153xSoil Sci Soc Am J. 65Hue NV, Vegas JA (2001) Manganese toxicity in Hawaiian oxisol affected by soil pH and organic amendments. Soil Sci Soc Am J 65:153-160. https:// doi. org/ 10. 2136/ sssaj 2001. 65115 3x
The kinetic and mechanisms of reaction of iron (III) with caffeic acid, chlorogenic acid, sinapic acid, ferulic acid and naringin. M J Hynes, M O'coinceanainn, 10.1016/j.jinorgbio.2004.05.009J Inorg Biochem. 98Hynes MJ, O'Coinceanainn M (2004) The kinetic and mechanisms of reaction of iron (III) with caffeic acid, chlorogenic acid, sinapic acid, ferulic acid and naringin. J Inorg Biochem 98:1457-1464. https:// doi. org/ 10. 1016/j. jinor gbio. 2004. 05. 009
Heath and environmental consciousness, cost of behavior and the purchase of organic food. P Kriwy, R A Mecking, 10.1111/j.1470-6431.2011.01004.xInt J Consum Stud. 36Kriwy P, Mecking RA (2012) Heath and environmental conscious- ness, cost of behavior and the purchase of organic food. Int J Consum Stud 36:30-37. https:// doi. org/ 10. 1111/j. 1470-6431. 2011. 01004.x
Effect of extraction techniques and solvents on antioxidant activity of pomegranate (Punica granatum L.) leaf and stem. M J Kaneria, M B Bapodara, S V Chanda, 10.1007/s12161-011-9257-6Food Anal Methods. 5Kaneria MJ, Bapodara MB, Chanda SV (2011) Effect of extraction techniques and solvents on antioxidant activity of pomegran- ate (Punica granatum L.) leaf and stem. Food Anal Methods 5:396-404. https:// doi. org/ 10. 1007/ s12161-011-9257-6
Remobilization of nutrients and its significance in plant nutrition. J F Loneragan, K Snowball, A D Robson, Transport and Transfer Process in Plants. Wardlaw IF, Passioura JBPhiladelphiaElsevier IncLoneragan JF, Snowball K, Robson AD (1976) Remobilization of nutrients and its significance in plant nutrition. In: Wardlaw IF, Passioura JB (eds) Transport and Transfer Process in Plants. Elsevier Inc, Philadelphia, pp 463-469
D J Merhaut, Handbook of plant nutrition. Baker AV, Pilbeam DJFloridaCRC PressMerhaut DJ (2007) Magnesium. In: Baker AV, Pilbeam DJ (eds) Handbook of plant nutrition. CRC Press, Florida, pp 145-181
Normatiza de Produção Orgânica no Brasil: a percepção dos agricultores familiares do assentamento da Chapadinha, Sobradinho (DF). Cmg Muñoz, Mgs Gómez, Jpg Soares, Amr Junqueira, 10.1590/1234.56781806-9479005402091590/ 1234. 56781 806-94790 05402 09Rev Econ Sociol Rural. 64Muñoz CMG, Gómez MGS, Soares JPG, Junqueira AMR (2016) Normatiza de Produção Orgânica no Brasil: a percepção dos agricultores familiares do assentamento da Chapadinha, Sobradinho (DF). Rev Econ Sociol Rural 64:361-376. https:// doi. org/ 10. 1590/ 1234. 56781 806-94790 05402 09
. U Niggli, QLIF Integrated Research Project. QualityLowIn-putFood. Organic EprintsNiggli U, (2009) QLIF Integrated Research Project. QualityLowIn- putFood. Organic Eprints, https:// orgpr ints. org/ id/ eprint/ 16595/. Accessed 27 January 2022.
Embrapa Pecuária Sudeste, São Calors. Ara Nogueira, A O Matos, Cafs Carmo, D J Silva, F L Monteiro, G B Souza, Gve Pitta, G M Carlos, H Oliveira, Comastri Filho, J Á Miyazawa, M , Oliveira Neto, W , Manual de Laboratórios: Solo, Água, Nutrição Vegetal, Nutrição Animal e Alimentos. Nogueira ARA, Souza GBTecido VegetalNogueira ARA, Matos AO, Carmo CAFS, Silva DJ, Monteiro FL, Souza GB, Pitta GVE, Carlos GM, Oliveira H, Comastri Filho JÁ, Miyazawa M, Oliveira Neto W (2005) Tecido Vegetal. In: Nogueira ARA, Souza GB (eds) Manual de Laboratórios: Solo, Água, Nutrição Vegetal, Nutrição Animal e Alimentos, 1st edn. Embrapa Pecuária Sudeste, São Calors, pp 145-200
Mineral content of some herbs and herbal teas by infusion and decoction. M M Ozcan, A Unver, T Uçar, D Arslan, 10.1016/j.foodchem.2007.07.042Food Chem. 106Ozcan MM, Unver A, Uçar T, Arslan D (2008) Mineral content of some herbs and herbal teas by infusion and decoction. Food Chem 106:1120-1127. https:// doi. org/ 10. 1016/j. foodc hem. 2007. 07. 042
Mineral nutrition of plants. R Pandey, Plant biology and biotechnology. Bahadur B, Rajam MV, Sahijram L, Krishnamurthy KVNew DelhiSpringer1Pandey R (2015) Mineral nutrition of plants. In: Bahadur B, Rajam MV, Sahijram L, Krishnamurthy KV (eds) Plant biology and bio- technology -, vol 1. plant diversity organization, function and improvement. Springer, New Delhi, pp 499-538
Resposta da erva mate (Ilex paraguariensis St. Hil.) à adubação mineral e orgânica em um latossolo vermelho aluminoférrico. C M Pandolfo, P A Floss, D M Croce, R C Dittrich, 10.5902/198050981740Ciência Florestal. 1340Pandolfo CM, Floss PA, Croce DM, Dittrich RC (2003) Resposta da erva mate (Ilex paraguariensis St. Hil.) à adubação mineral e orgânica em um latossolo vermelho aluminoférrico. Ciência Flo- restal 13:37-45. https:// doi. org/ 10. 5902/ 19805 09817 40
Determination of toxic elements in yerba mate by ICP-MS after diluted acid digestion under O 2 pressure. R B Pardinho, Dalla Vecchia, P Mendes, Alg , Bizica Mellopa, F A Duarte, Emm Flores, 10.1016/j.foodchem.2018.04.11204. 112Food Chem. 263Pardinho RB, Dalla Vecchia P, Mendes ALG, BiziCA MelloPA, Duarte FA, Flores EMM (2018) Determination of toxic elements in yerba mate by ICP-MS after diluted acid digestion under O 2 pressure. Food Chem 263:37-41. https:// doi. org/ 10. 1016/j. foodc hem. 2018. 04. 112
Acid Decomposition of Yerba Mate (Ilex paraguariensis) Using a reflux system for the evaluation of Al. C Pereira, A O Souza, E Q Oreste, Mja Cidade, S Cadore, A S Ribeiro, M A Vieira, 10.5935/0103-5053.20150317J Brazil Chem Soc. 27317and Zn contents by atomic spectrometric techniquesPereira C, Souza AO, Oreste EQ, Cidade MJA, Cadore S, Ribeiro AS, Vieira MA (2016) Acid Decomposition of Yerba Mate (Ilex para- guariensis) Using a reflux system for the evaluation of Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ob and Zn contents by atomic spectrometric techniques. J Brazil Chem Soc 27:685-693. https:// doi. org/ 10. 5935/ 0103-5053. 20150 317
Evaluation of inorganic elements in cat's claw teas using ICP OES and GF AAS. J B Pereira Junior, G F Dantas, 10.1016/j.foodchem.2015.09.057Food Chem. 196Pereira Junior JB, Dantas GF (2016) Evaluation of inorganic elements in cat's claw teas using ICP OES and GF AAS. Food Chem 196:331-337. https:// doi. org/ 10. 1016/j. foodc hem. 2015. 09. 057
Mineral in balance due to manganese excess in triticales. V M Quartin, M L Antunes, M C Muralha, M M Souza, M A Nunes, 10.1081/PLN-100000319J Plant Nutr. 24Quartin VM, Antunes ML, Muralha MC, Souza MM, Nunes MA (2001) Mineral in balance due to manganese excess in triticales. J Plant Nutr 24:175-189. https:// doi. org/ 10. 1081/ PLN-10000 0319
Consumer behavior and purchase intention for organic food: a review research agenda. J Rana, J Paul, 10.1016/j.jretconser.2017.06.004J Retail Consum Servies. 38Rana J, Paul J (2017) Consumer behavior and purchase intention for organic food: a review research agenda. J Retail Consum Servies 38:157-165. https:// doi. org/ 10. 1016/j. jretc onser. 2017. 06. 004
The correlation of metal content in medicinal plants and their water extracts. S Randjelovic, D Kostic, S S Mitic, A Zarubica, M Mitic, J Velickovic, 10.2298/HEMIND120703098RHemijska Industria. 67Randjelovic S, Kostic D, Mitic SS, Zarubica A, Mitic M, Velickovic J (2013) The correlation of metal content in medicinal plants and their water extracts. Hemijska Industria 67:585-691. https:// doi. org/ 10. 2298/ HEMIN D1207 03098R
Sustainable food consumption: an overview of contemporary issues and polices. L Reisch, U Eberle, S Lorek, 10.1080/15487733.2013.11908111Sustainably: Science. Pract Policy. 9111Reisch L, Eberle U, Lorek S (2013) Sustainable food consumption: an overview of contemporary issues and polices. Sustainably: Science. Pract Policy 9:7-25. https:// doi. org/ 10. 1080/ 15487 733. 2013. 11908 111
Chemical composition of Ilex paraguariensis St. Hil. under different management conditions in seven localities of Paraná State. C B Reissmann, M I Radomski, Rmb Quadros, 10.1590/S1516-891319990002000091590/ S1516-89131 99900 02000 09Braz Arch Biol Technol. 42Reissmann CB, Radomski MI, Quadros RMB (1999) Chemical com- position of Ilex paraguariensis St. Hil. under different manage- ment conditions in seven localities of Paraná State. Braz Arch Biol Technol 42:187-194. https:// doi. org/ 10. 1590/ S1516-89131 99900 02000 09
What is principal component analysis?. M Ringnér, 10.1038/nbt0308-303Nat Biotechnol. 26Ringnér M (2008) What is principal component analysis? Nat Biotech- nol 26:303-304. https:// doi. org/ 10. 1038/ nbt03 08-303
Effect of yerba mate (Ilex paraguariensis) extract on the metabolism of diabetic rats. D S Rocha, L Casagrande, Jfa Model, J T Santos, A L Hoefel, L C Kucharski, 10.1016/j.biopha.2018.05.132Biomed Pharmacother. 105Rocha DS, Casagrande L, Model JFA, Santos JT, Hoefel AL, Kucharski LC (2017) Effect of yerba mate (Ilex paraguariensis) extract on the metabolism of diabetic rats. Biomed Pharmacother 105:370- 376. https:// doi. org/ 10. 1016/j. biopha. 2018. 05. 132
Mineral and centesimal composition of conventional and organic cultivars sweet potato (Ipomoea batatas (L.) Lam) using chemometric tools. Amp Santos, J S Lima, I F Santos, Erf Silva, F A Santana, Dggr Araujo, Santos Lo, 10.1016/j.foodchem.2017.12.063Food Chem. 273Santos AMP, Lima JS, Santos IF, Silva ERF, Santana FA, Araujo DGGR, Santos LO (2019) Mineral and centesimal composition of conventional and organic cultivars sweet potato (Ipomoea bata- tas (L.) Lam) using chemometric tools. Food Chem 273:166-171. https:// doi. org/ 10. 1016/j. foodc hem. 2017. 12. 063
Assessing sustainable diets within the sustainability of food systems. C Schader, Stolzem, U Niggli, Proceedings of an International Workshop. A. Meybeck, S. Redfern, F. Paoletti, & C. Strassneran International WorkshopRomeFAOHow the organic food system contributes to sustainabilitySchader C, StolzeM, Niggli U (2015) How the organic food system contributes to sustainability. In A. Meybeck, S. Redfern, F. Pao- letti, & C. Strassner (Eds.), Assessing sustainable diets within the sustainability of food systems. Proceedings of an International Workshop (pp. 27-36). Rome: Food and Agriculture Organization of the United Nations (FAO).
In vitro bioaccessibility gastro-instetinal digestion and total content of these metais in different BRazilian brands of yerba mate tea. Bfo Schmite, A Bitobrovec, Acm Hacke, R P Pereira, P L Weinert, B E Anjos, 10.1016/j.foodchem.2018.12.102Food Chem. 281102Schmite BFO, Bitobrovec A, Hacke ACM, Pereira RP, Weinert PL, Anjos BE (2019) In vitro bioaccessibility gastro-instetinal diges- tion and total content of these metais in different BRazilian brands of yerba mate tea. Food Chem 281:285-293. https:// doi. org/ 10. 1016/j. foodc hem. 2018. 12. 102
Chlorogenic acids and flavonoids extraction during the preparation of yerba mate based beverages. Tff Silveira, A D Meinhart, Tcl Souza, Ece Cunha, M R Moraes, H T Godoy, 10.1016/j.foodres.2017.09.098Food Res Int. 102Silveira TFF, Meinhart AD, Souza TCL, Cunha ECE, Moraes MR, Godoy HT (2017) Chlorogenic acids and flavonoids extraction during the preparation of yerba mate based beverages. Food Res Int 102:348-354. https:// doi. org/ 10. 1016/j. foodr es. 2017. 09. 098
Phenolic compounds from yerba mate based beverages -a multivariate optimization. Tff Silveira, A D Meinhart, Tcl Souza, Teixeira Filho, J Moraes, M R Godoy, H T , 10.1016/j.foodchem.2015.06.031Food Chem. 190Silveira TFF, Meinhart AD, Souza TCL, Teixeira Filho J, Moraes MR, Godoy HT (2016) Phenolic compounds from yerba mate based beverages -a multivariate optimization. Food Chem 190:1159- 1167. https:// doi. org/ 10. 1016/j. foodc hem. 2015. 06. 031
Relation among taste-related compounds (phenolic and caffeine) and sensory profile of erva-mate (Ilex Paraguariensis). N M Streit, Lhr Hecktheuer, M W Canto, C A Mallmann, L Streck, T Parodi, L P Canterle, 10.1016/j.foodchem.2006.05.028Food Chem. 102Streit NM, Hecktheuer LHR, Canto MW, Mallmann CA, Streck L, Parodi T, Canterle LP (2007) Relation among taste-related com- pounds (phenolic and caffeine) and sensory profile of erva-mate (Ilex Paraguariensis). Food Chem 102:560-564. https:// doi. org/ 10. 1016/j. foodc hem. 2006. 05. 028
Antonides G (2012) Segment of sustainable food consumer: a literature review. Mcd Verain, J Bartels, H Dagevos, S J Sijtsema, M C Onwezen, 10.1111/j.1470-6431.2011.01082.xInt J Consum Stud. 36Verain MCD, Bartels J, Dagevos H, Sijtsema SJ, Onwezen MC, Anton- ides G (2012) Segment of sustainable food consumer: a literature review. Int J Consum Stud 36:123-132. https:// doi. org/ 10. 1111/j. 1470-6431. 2011. 01082.x
A systematic review of organic versus conventional food consumption: is there a measurable benefit on human health. V Vigar, S Myers, C Oliver, J Arellano, S Robinson, C Leifert, 10.3390/nu12010007Nutrients. 1210007Vigar V, Myers S, Oliver C, Arellano J, Robinson S, Leifert C (2020) A systematic review of organic versus conventional food consump- tion: is there a measurable benefit on human health? Nutrients 12:696-727. https:// doi. org/ 10. 3390/ nu120 10007
Advances of organic products over conventional productions with respect to nutritional quality and food security. X Yu, L Guo, G Jiang, Y Song, M A Muminov, 10.1016/j.chnaes.2018.01.00901. 009Acta Ecol Sin. 38Yu X, Guo L, Jiang G, Song Y, Muminov MA (2018) Advances of organic products over conventional productions with respect to nutritional quality and food security. Acta Ecol Sin 38:53-60. https:// doi. org/ 10. 1016/j. chnaes. 2018. 01. 009
Plant nutrition for sustainable development and global health. P J White, P H Brown, 10.1093/aob/mcq085Ann Bot. 105White PJ, Brown PH (2010) Plant nutrition for sustainable develop- ment and global health. Ann Bot 105:1073-1080. https:// doi. org/ 10. 1093/ aob/ mcq085
The world of organic agriculture: Statistics & Emerging Trends 2021. H Willer, J Trávnícek, C Meier, B Schlatter, IFOAM Publish OnlineWiller H, Trávnícek J, Meier C, Schlatter B (2021) The world of organic agriculture: Statistics & Emerging Trends 2021. IFOAM Publish Online, https:// www. fibl. org/ filea dmin/ docum ents/ shop/ 1150-organ ic-world-2021. pdf. Accessed 27 January 2021.
Organic foods. C K Winter, S F Davis, 10.1111/j.1750-3841.2006.00196.xJ Food Sci. 71Winter CK, Davis SF (2006) Organic foods. J Food Sci 71:R117-R124. https:// doi. org/ 10. 1111/j. 1750-3841. 2006. 00196.x
Nutritional quality of organic versus conventional fruits, vegetable and grains. V Worthington, 10.1089/107555301750164244J Altern Complement Med. 7244Worthington V (2001) Nutritional quality of organic versus conven- tional fruits, vegetable and grains. J Altern Complement Med 7:161-173. https:// doi. org/ 10. 1089/ 10755 53017 50164 244
Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
| [
-0.1114584356546402,
-0.008007370866835117,
-0.08341909945011139,
0.03971495479345322,
0.0603821724653244,
0.04826751723885536,
0.006219347007572651,
0.06842990219593048,
-0.02796795219182968,
0.04313615709543228,
-0.0546693280339241,
-0.13829147815704346,
0.03662288933992386,
-0.087105400... |
Foot Length as a Predictor of Weight in Children up to Five Years
2018
Md Shameem
Department of Pediatric Neurology
National Institute of Neuroscience and Hospital
AgargaonDhaka
Nazneen Akhter Banu
Department of Pediatric Neurology
National Institute of Neuroscience and Hospital
AgargaonDhaka
A N M Nurul
Department of Pediatric Neurology
National Institute of Neuroscience and Hospital
AgargaonDhaka
Haque Bhuiyan
Department of Pediatric Neurology
National Institute of Neuroscience and Hospital
AgargaonDhaka
Ariful Islam
Department of Pediatric Neurology
National Institute of Neuroscience and Hospital
AgargaonDhaka
Foot Length as a Predictor of Weight in Children up to Five Years
The Journal of Teachers Association RMC
Rajshahi3122018Original Article 1 Assistant Professor, Neonatology, Rajshahi Medical College, Rajshahi 2 Professor, Department of Pediatrics, Sir Salimullah Medical College, Dhaka 3 Registrar, (Pediatrics), 300 Bedded Hospital, Khanpur, Narayanganj 4 Associate Professor,
Weight measurement is essential for the management of pediatric patients to calculate the dose of the drugs. But it is not possible to move the child to a weighing scale for determination of body weight when the child is in a critical condition. The purpose of this study was to check if foot length correlates with child's body weight in our situation and to devise a formula for prediction of weight based on foot-length observed. This Cross-sectional study was carried out in the Department of Pediatrics, Sir Salimullah Medical College, Mitford hospital, Dhaka over a period of 12 months between January 2008 and December 2008. A total of 300 children, between 0 day to five years, meeting the predefined eligibility criteria were included in the study. Using the available data, simple linear regression analysis was performed between the dependent variable weight and independent variable foot length. The estimated linear regression line was: Predicted weight (kg) = a+ [b× foot length]. Data were analyzed using correlation coefficient (r) between foot length and children's weight. In this study correlation between foot length and weight (r) was 0.92(P<0.001) indicating a perfect linear relationship between them. In the present study determination of correlation (r 2 ) was 0.85 meaning that 85% of the variability in weight might be explained by variation in foot length. The estimated linear regression line was: Predicted weight (kg) = -4.64 + [1.12 X foot length], where-4.64 was the intercept and 1.12 was the slope of the regression line. Comparison between measured weight and predicted weight revealed that94% of variation between measured weight and predicted weight was within ±2kg. More than half of the cases (58.3%) the above-mentioned variations were within ±1kg. This study concluded, there was a strong correlation between foot length and weight in children up to five years. The body weight in children from 0 days up to the age of 5 years can be predicted from foot length. Prediction of weight simply by foot-length measurement could be a great help to the health care provider including doctors and health workers for drug dose calculation in critically ill children.
Introduction
Weight measurement is essential for the management of pediatric patients. Drug dosage in pediatric patient is calculated depending on weight of the child. But it is not possible to move the child to a weighing scale for determination of body weight when a child presents in a critical condition. Critically ill child gets surrounded by doctors and nurses who immediately begin procedures such as quick clinical evaluation, securing intravenous access, administration of oxygen and at times undertaking cardiopulmonary resuscitation. Difficulty is also faced by the health workers at field level to measure weight due to non-availability of costly weighing scale. To treat a child, they have to estimate a wide range of drug dosage based on chronological age, which may not be specific and appropriate for a particular child. Similarly, their practice of drug dosage calculation from adult dose may not be appropriate or safe for a particular child.
A simple, handy, safe and less costly method for the measurement of weight is an immense need. Foot-length measurement could be the right answer in that situation. Previous studies done abroad in the neonates and young children showed that foot length can be used to predict weight, length and nasotracheal tube length. 1-8 Measuring foot-length is possible even when a child is in critical state. Again foot-length measurement might be regarded as a simple, easy, quick, practical method to predict weight without using weighing scale by the health worker at the field level.
Studies done abroad to predict weight based on foot length mostly included neonates 1-8 and in one study children up to two years of age were included. 1 In developing countries, children do not visit their doctors regularly; their recent weight record (Pre-illness weight) is often not available. Most parents do not keep the medical records diligently. So, the records of pre-morbid weight are not available. Faced with such situation, prediction of weight simply by foot-length measurement could be of great help to the health care provider including doctors and health workers. The purpose of the present study was, therefore, to check if foot length correlates with child's body weight in our situation and to devise a formula for prediction of weight based on footlength. Thus, the present study was intended to determine the correlation between foot -length and weight in children from 0 days up to five years, to predict weight using simple foot-length measurement and to compare the predicted weight with the measured weight.
Materials and Methods
This Cross-sectional study was carried out in the Department of Pediatrics, Sir Salimullah Medical College, Mitford hospital, Dhaka over a period of 12 months between January 2008 and December 2008. A total of 300 children between 0 day to five years who met the predefined eligibility criteria were included in the study. Bare foot length in cm was measured using Vernier scale. The children were then weighted using NNC (National Nutrition Council) bar scale. Using the available data, simple linear regression analysis was performed between the dependent variable weight and independent variable foot length. The estimated linear regression line was: Predicted weight (kg) = a+ [b× foot length]. Data were analyzed using correlation coefficient (r) between foot length and children's weight.
Results 300 children between 0 day to 5 years of age were enrolled in this cross sectional study. Table I showed the base line characteristics of the study population. Studied children were divided in different age group. More than 60% of the studied population was below 2 years of age. Among 67 newborn, number of preterm LBW were 44 and the rest 23 were normal term newborn. were male and 35.3% were female. Statistical analysis of the relation between footlength and measured weight was done. The correlation between foot length and measured weight (r) was 0.92, (P<0.001) which indicate strong relationship between the two variables. The determination of correlation (r 2 ) was 0.85. This indicates that 85% of the variability in weight might be explained by variation in foot length. 85% of the variability in weight might be explained by the liner regression model. Using the available data, simple linear regression analysis was performed between the dependent variable measured weight (kg) and independent variable foot length (cm). The estimated linear regression line is given below:
Predicted weight (kg) = -4.64 + 1.12 × foot length where 4.64 was the intercept and 1.12 was the slope of the regression line. The slope value 1.12 indicated that 1 unit change of foot length could change predicted weight 1.12 times.
This study found statistically significant linear relationship between foot length and measured weight (r= 0.92, p <0.001). Most of the measured weight values were within 95% confidence limits of predicted weight. The regression line best fitted the present data.
Measured weight was estimated using BNNC bar scale and predicted weight was estimated by using simple linear regression formula. The maximum difference between measured weight and predicted weight lies between -2.44 and +2.87kg. Mean difference between measured weight and predicted weight was -0.19 ±1.12 kg. Table III showed that in 94% cases the variation between measured weight and predicted weight in studied population was within ±2kg. More than half of the cases (58.3%), the above-mentioned variations were within ±1kg. Table IV showed mean of variation between measured weight and predicted weight in different age group is the lowest in 48-60 month age group and highest in the 0-1 month age group. Table V showed the variation between measured weight and predicted weight in 0-1-month age group, in half of the cases were within -1 to 0 kg (47.8%) and with in -1 to -2 kg in other half of the cases (52.2%). In 1to 12-month age group, the above-mentioned variation in 36.9% cases was within 0 to 1 kg and in 27.7% cases were within -1 to 0 kg. In 12 to 24 months age group, the abovementioned variation in 36.2% cases was within 0 to 1 kg and in 46.6% cases were within -1 to 0 kg. In 24 to 36 months age group, the variation in half of the cases (47%) was within -1 to 0 kg. In 36 to 48 months age group, the variation in half of the cases (52%) was within 0 to -2 kg. In 48 to 60 months age group, the above-mentioned variation in more than one third of the cases (37.2%) was within 0 to 1 kg. Table VI showed least variations between measured weight and predicted weight (±1kg) in different age group of studied population. The above mentioned least variation (±1kg) was found in 83% cases in 24-36 month age group and it was in between 40% to 65% of cases in other age groups.
Discussion
Predicting weight on the basis of chronological age is fraught due to the presence of rampant moderate to severe malnutrition in our community. Weighing a child is often difficult while they are being admitted in hospital in a critical condition. At the field level carrying a weighing machine by a health worker is also difficult. Foot length can be easily measured using a Vernier scale, which is neither costly nor technically challenging to use.
Children up to five years of age constituted bulk of the admissions to the pediatric unit as the emergency cases in this country. This study demonstrated strong correlation (r) between foot length and weight in children up to the age of five years (r = 0.92 P<0.001). Bavdekar et al. 1 found similar correlation (r) between foot length and weight in children up to the age of two years (r = 0.88). James et al. 2 In their study on neonates of gestational age 26-48 weeks, found a positive linear correlation between foot length and birth weight ranging from 0.89 to 0.91 in all gestational ages. In the previous study the strong correlation between foot length and weight was existed in the children up to the age of 2 years but the present study indicated that this strong correlation also extended to children up to the age of 5 years. In this study the correlation (r 2 ) between foot-length and body weight was 0.85 indicating that 85% of the variation in weight might be explained by the foot length which compares well with findings of Bavdekar et al. 1 (r 2 = 0.88).
In the present study a linear regression equation was developed from the available data to predict weight using simple foot-length measurement. Predicted weight (kg) = -4. In this study measured weight was compared with predicted weight which showed that 94% of variations between measured weight and predicted weight in studied population was within ±2kg. More than half of the cases (58.3%) in the studied population the above-mentioned variations were within ±1kg. The least variation (0±1kg) between measured weight and predicted weight was found in 83% cases in 24-36-month age group and it was in between 40 to 65% of cases in other age groups. So, using this formula one can predict weight that would be very close to the measured weight in children from 0 days up to the age of 5 years.
Conclusion
This study concluded, there was a strong correlation between foot length and weight in children up to five years. The body weight in children from 0 days up to the age of 5 years can be predicted from foot length. Prediction of weight simply by foot-length measurement could be a great help to the health care provider including doctors and health workers for drug dose calculation in critically ill children.
Keywords: Foot length, prediction of weight. TAJ 2018; 31: No-2: 39-44
Table I :
IBaseline characteristics of the study population (n=300)Age (in month)
Number
Percentage
0 -1
67
22.3
1 -12
65
21.7
12 -24
58
19.3
24 -36
17
5.7
36-48
50
16.7
48 -60
43
14.3
Table II showed-among 300 studied children 64.7%
Table II :
IIStudy population according to sex
(n=300)
Sex
Number
Percentage
Male
194
64.7
Female
106
35.3
Total
300
100
Table III :
IIIPattern of variation between
measured weight and predicted weight in
studied population (n=300)
Variation between
measured weight
and predicted
weight (kg)
Number
Percentage
0 to 1
70
23.3
1 to 2
29
9.7
2 to 2.87
12
4
-1 to 0
105
35
-1 to -2
78
26
-2 to -2.44
6
2
Total
300
100
Table IV :
IVMean of variation between measured weight and predicted weight in different age group of studied population (n=300)Age group
(in month)
Mean of variation
(Kg.)
0 -1
-0.96
1 -12
0.32
12 -24
-0.33
24 -36
0.9
36-48
0.49
48 -60
0.16
Table V :
VPattern of variation between measured weight and predicted weight in different age group of studied population (n=300)Different
age
group
(month)
Variation
0 to 1
(kg)
n
(%)
Variation
1 to 2
(kg)
n
(%)
Variation
2 to 2.87
(kg)
n
(%)
Variation
-1 to 0
(kg)
n
(%)
Variation
-1 to -2
(kg)
n
(%)
Variation
-2to -2.44
(kg)
n
(%)
Total
studied
population
n
(%)
0 -1
0
(0)
0
(0)
0
(0)
32 (47.8)
35 (52.2)
0
(0)
67 (100)
1 -12
24 (36.9)
7 (10.8)
4
(6.2)
18 (27.7)
12 (18.5)
0
(0)
65 (100)
12 -24
21 (36.2)
2 (3.45)
0
(0)
27 (46.6)
8 (13.8)
0
(0)
58 (100)
24 -36
1
(5.9)
4 (23.5)
0
(0)
8
(47)
4 (23.5)
0
(0)
17 (100)
36-48
7
(14)
9 (18.0) 8
(16)
13 (26)
13 (26)
0
(0)
50 (100)
48 -60
16 (37.2)
7 (16.3) 0
(0)
7 (16.3)
6
(14)
6
(14)
43 (100)
Table VI :
VILeast variation between measured weight and predicted weight (±1kg) in different age
group of studied population (n=174)
Different age
group
(month)
Variation
0 to 1
(kg)
n
Variation
-1 to 0
(kg)
n
Total
population
n
(%)
Total
least
variation
(±1kg)
n
(%)
0 -1
0
32
67
(100)
32
(48)
1 -12
24
18
65
(100)
42
(65)
12 -24
21
27
58
(100)
48
(83)
24 -36
1
8
17
(100)
9
(53)
36-48
7
13
50
(100)
20
(40)
48 -60
16
7
43
(100)
23
(54)
Total
69
105
300
(100)
174
(58)
64 + [1.12 X foot length] where -4.64 is the intercept and 1.12 is the slope of the regression line. According to study done by Bavdekar et al. 1 predicted weight (kg) = -5.15 + [1.35 X foot length] where -5.15 is the intercept and 1.35 is the slope of the regression line. It should be realized that there are population variation in anthropometric dimensions, which are influenced by genetics and environmental factors. So the regression equations generated in these studies may vary in different population. However, the equation generated in the present study might be very useful in predicting weight in our community only.
Prediction of weight of Indian children aged up to two years based on foot-length: Implications for emergency areas. S B Bavdekar, S Sathe, Jani P , Ind pediatr. 43Bavdekar SB, Sathe S, Jani P. Prediction of weight of Indian children aged up to two years based on foot-length: Implications for emergency areas. Ind pediatr 2006; 43: 125-30.
Foot length -a new and potentially useful measurement in the neonate. D K James, E H Dryburgh, M L Chiswick, Arch Dis child. 54James DK, Dryburgh EH, Chiswick ML. Foot length -a new and potentially useful measurement in the neonate. Arch Dis child 1979; 54: 226-30.
Foot length, an accurate predictor nasotracheal tube length in neonates. N D Embleton, S A Deshpande, D Scott, C Wright, Dwa Milligan, Arch Dis Child Fetal Neonatal Ed. 85Embleton ND, Deshpande SA, Scott D, Wright C, Milligan DWA. Foot length, an accurate predictor nasotracheal tube length in neonates. Arch Dis Child Fetal Neonatal Ed 2001; 85: F60-F4.
Detection of low birth weight newborns by foot length as proxy measure of birth weight. S S Shah, P S Shrestha, F C Gami, Arch Dis child. 90Shah SS, Shrestha PS, Gami FC. Detection of low birth weight newborns by foot length as proxy measure of birth weight. Arch Dis child 2005; 90: A9-A 10.
Relationship between the surrogate anthropometric measures, foot length and chest circumference and birth weight among newborns of Sarlahi, Nepal. L C Mullany, G L Darmsrtadt, S K Khatry, S C Leclerq, J M Tilesch, Euro j Clin Nutr. 611Mullany LC, Darmsrtadt GL, Khatry SK, Leclerq SC, Tilesch JM. Relationship between the surrogate anthropometric measures, foot length and chest circumference and birth weight among newborns of Sarlahi, Nepal. Euro j Clin Nutr 2007; 61(1): 40-6.
Foot length as surrogate for birth weight in the newborn-A study of 500 cases. M Shahidullah, N A Begum, M Q Hassain, C A Kawser, M Mannan, N Islam, Bangladesh J Child Health. 281Shahidullah M, Begum NA, Hassain MQ, Kawser CA, Mannan M, Islam N. Foot length as surrogate for birth weight in the newborn-A study of 500 cases. Bangladesh J Child Health 2004; 28(1): 18- 22.
Foot tape measure for identification of low birth weight newborns. S S Hirve, B R Ganatra, Ind Pediatr. 301Hirve SS, Ganatra BR. Foot tape measure for identification of low birth weight newborns. Ind Pediatr 1993; 30 (1): 25-29.
Foot length measurement in the neonate. J R Gohil, M Sosi, S N Vani, Ind J Paediatr. 585Gohil JR, Sosi M, Vani SN et al. Foot length measurement in the neonate. Ind J Paediatr 1991; 58 (5): 675-77.
Prediction of height from foot length: Use of measurement in field surveys. I H Rutishauser, Arch Dis. 43Rutishauser IH. Prediction of height from foot length: Use of measurement in field surveys.Arch Dis Child1968; 43: 310-12
Detection of Low birth weight newborn babies by anthropometic measurements in Bangladesh. F Huque, A M Hussain, Indian J Paediatr. 582Huque F, Hussain AM. Detection of Low birth weight newborn babies by anthropometic measurements in Bangladesh. Indian J Paediatr 1991; 58 (2) 223-31
Determination of sex from the foot measurements. A K Agnihotri, S Shukla, B Purwar, The Internet J Foren Science. 21Agnihotri AK, Shukla S, Purwar B. Determination of sex from the foot measurements. The Internet J Foren Science 2007; 2: 1.
Is manual foot length measurement of comparable value to ultrasound femur and humerus measurement in anatomical studies for the assessment of fetal age?. A M Bulandra, M Kuczera, J Machnik, Folia Morphol. 632Bulandra AM, Kuczera M, Machnik J. et al Is manual foot length measurement of comparable value to ultrasound femur and humerus measurement in anatomical studies for the assessment of fetal age? Folia Morphol 2004; 63 (2): 203-07
Foot Length'-a Newer Approach in Neonatal Anthropometry. A Mathur, S K Tak, P Kothari, J Tropi Pediatr. 306Mathur A, Tak SK, Kothari P. Foot Length'-a Newer Approach in Neonatal Anthropometry. J Tropi Pediatr 1984; 30 (6): 333-36
Foot length, creases, nails and ossification centres in the estimation of intra-uterine age of the fetus. V N Ambade, A P Dongre, J Foren Med Toxico. 201Ambade V. N, Dongre A. P. "Foot length, creases, nails and ossification centres in the estimation of intra-uterine age of the fetus. J Foren Med Toxico 2003; 20(1).
Ordinary level physics. 4 th ed. New Delhi: Arnold-Heinemann. Abbot AFAbbot AF, editor. Ordinary level physics. 4 th ed. New Delhi: Arnold-Heinemann, 1992: 5-7.
Bar scale-a good inexpensive weighing scale for developing countries. D K Das, M A Mannan, Wahiduzzaman, Mq-K Talukder, Bangladesh J Child Health. 171Das DK, Mannan MA, Wahiduzzaman, Talukder MQ-K, Bar scale-a good inexpensive weighing scale for developing countries. Bangladesh J Child Health 1993; 17(1): 19-21.
Weighing Scale, design and choices. J O Burns, J F Rhode, Ind J Paediatr. 55SupplBurns JO, Rhode JF, Weighing Scale, design and choices. Ind J Paediatr (Suppl) 1988; 55: S31-S37.
Evaluation and synthesis of scales, mothers and children care. Anonymous, Appropriate Technology for Health. 1724Anonymous. Evaluation and synthesis of scales, mothers and children care. Appropriate Technology for Health (ATH), Newsletter no-17, 1985: 24.
Measurement of child's growth (practical). A J Amanatullah, Mannan MADhaka, PABangladesh national nutrition councilAmanatullah AJ, Measurement of child's growth (practical). In: Mannan MA, editor. A guide on nutrition education. Dhaka, PA: Bangladesh national nutrition council, 1995: 67-69.
Correlation of foot length with height and weight in school age children. T B Grivas, C Mihas, A Arapaki, J Forensic Leg Med. 152Grivas TB, Mihas C, Arapaki A. Correlation of foot length with height and weight in school age children. J Forensic Leg Med 2008; 15 (2): 89-95.
Prediction of Anthropometric foot characteristics in children. S C Morrison, B R Durward, G F Watt, J Am Pediatric Med Assoc. 996Morrison SC, Durward BR, Watt GF et al. Prediction of Anthropometric foot characteristics in children. J Am Pediatric Med Assoc 2009; 99 (6): 497-502.
Estimation of height from the measurements of foot length in Gujarat region. S M Patel, G V Shah, S V Patel, J Anat Soc Ind. 561Patel SM, Shah GV, Patel SV. Estimation of height from the measurements of foot length in Gujarat region. J Anat Soc Ind 2007; 56 (1): 25-7.
Change of foot size with weight bearing. A study of 2829 children 3 to 18 years of age. J C Cheng, S S Leung, A K Leung, Clin Orthop Relat Res. 342Cheng JC, Leung SS, Leung AK. Change of foot size with weight bearing. A study of 2829 children 3 to 18 years of age. Clin Orthop Relat Res 1997; 342: 123-31
WHO Country Cooperation Strategy. WHO Country Cooperation Strategy, Bangladesh- 2008-2013. (http:// www. searo. who.int /en/ Section1430/.../Section1618.htm, accessed on 3 January 2009).
M M Hoque, ABC of research methodology and biostatistics.1 st ed. Dhaka, Hoque MM. 349Hoque MM. ABC of research methodology and biostatistics.1 st ed. Dhaka, Hoque MM, 2009: 349-
All correspondence to: Md. Shameem Assistant Professor. shameemnova@gmail.comNeonatology Rajshahi Medical College Rajshahi, Bangladesh E-mailAll correspondence to: Md. Shameem Assistant Professor, Neonatology Rajshahi Medical College Rajshahi, Bangladesh E-mail: shameemnova@gmail.com
| [
-0.07149787247180939,
0.05314354598522186,
0.005450761411339045,
0.10929913818836212,
-0.10056685656309128,
0.06302371621131897,
-0.10364686697721481,
0.1697421669960022,
0.021131934598088264,
0.0334225632250309,
0.12677529454231262,
-0.051693789660930634,
0.05205307900905609,
0.1503450274... |
Person, Place, Time and COVID-19 Inequities
4 from February to December 2020
Alina S Schnake-Mahl
Usama Bilal
Dornsife School of Public Health
Drexel University
PhiladelphiaPA, Alina
Department of Epidemiology and Biostatistics
Dornsife School of Public Health
Schnake-Mahl and Usama Bilal)
Drexel University
PhiladelphiaPAUsama Bilal
Person, Place, Time and COVID-19 Inequities
4 from February to December 20201 Correspondence to Dr. Alina Schnake-Mahl, Urban Health Collaborative, Dornsife School of Public Health, Drexel University, 3600 Market Street Philadelphia, 7 th floor, PA 19104 (email: Author affiliations: Urban Health Collaborative, This work was funded with support from the NIH under grant DP5OD26429 and the Robert Wood Johnson Foundation under grants RWJF 77644 and 78325. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Conflict of interest: none declared Running Head: Person, Place, Time, and COVID-19 The data underlying this article are available in the 2019 Novel Coronavirus Visual Dashboard operated by the Johns Hopkins University Center for Systems Science and Engineering (JHU CSSE), at https://github.com/CSSEGISandData/COVID-19. Editor's note: The opinions expressed in this article are those of the authors and do not necessarily reflect the views of the American Journal of Epidemiology. O R I G I N A L U N E D I T E D M A N U S C R I P T To support our argument, we present a series of figures exploring the heterogeneous relationships between places, people, and time, using US county-level publicly available COVID-19 mortality data from February to December 2020 from Johns Hopkins University. Longitudinal and more geographically granular data that allows for disaggregation by person, place, and time will improve our estimation and understanding of inequities in COVID-19. Abbreviations CDC: Centers for Disease Control and Prevention COVID-19: Coronavirus disease 2019 O R I G I N A L U N E D I T E D M A N U S C R I P T 3 In their article, "A Geography of Risk: Structural Racism and COVID-19 Mortality in the United States," To support our argument, we explore the heterogeneous relationships between populations defined by place, people, and time, throughout the COVID-19 pandemic in the US. Given the limited availability of reliable longitudinal data on the racial and ethnic composition of COVID-19 cases and deaths, we take an ecological approach, using publicly available COVID-19 data O R I G I N A L U N E D I T E D M A N U S C R I P TCOVID-19health disparitieshealth equitygeography
In their commentary, Zalla et al. argue that the approach taken by Centers for Disease Control (CDC) comparing the proportion of COVID-19 deaths by race/ethnicity to a weighted population distribution ignores how systemic racism structures the composition of places. While the CDC has abandoned their measure, they do so because of the changing geographic distribution of COVID-19, not because the measure underestimates racial disparities. We further Zalla et al.'s argument, advocating for a relational approach to estimating COVID-19 racial inequities that integrates the reciprocal relationship between context and composition through the interaction of places and people over time.
co-authors highlight the need to take an historical approach to understanding the geography of racial inequities in COVID- 19. Their discussion of the history and continued effects of racism helps to concretely demonstrate the deeply problematic implications of "race-neutral" methodological and policy decisions and need to consider how racism structures risk. Summarizing their argument, racism leads to inequitable residential contexts with disparate exposure risks, and so adjusting for geography "bakes in" inequities, treating racism as a confounder rather than an exposure itself (1).
While the method is no longer in use by CDC (3), we believe further discussion is important to improve the monitoring of inequities in COVID-19 and other diseases. The key argument of Zalla et al. is that racism shapes the distribution of people by race, both within and between local areas. We believe that the CDC methodology also ignores the interconnected nature of context and composition. We propose adopting a relational approach, integrating the reciprocal relationship between context and composition through the interaction of places and people over time (4). Places and populations are not socially, politically, or environmentally neutral or isolated(5), so treating them as inconsequential beyond composition reinforces a false and ahistorical approach to measuring inequities. We argue here for the importance of considering mutually reinforcing and dynamic COVID-19 disparities across and between people, places, and time (6). To support our argument, we explore the heterogeneous relationships between populations defined by place, people, and time, throughout the COVID-19 pandemic in the US.
Given the limited availability of reliable longitudinal data on the racial and ethnic composition of COVID-19 cases and deaths, we take an ecological approach, using publicly available COVID-19 data
O R I G I N A L U N E D I T E D M A N U S C R I P T
from February to December 2020 from Johns Hopkins University (7), and assign deaths to counties according to the majority (>60%) racial/ethnic group. Our approach obscures within county inequities (mostly expressed through residential segregation within cities) and is not meant to imply that county racial composition reflects the race/ethnicity of individual cases. We additionally classify geographies as urban, suburban, or rural (8), based on the Rural Urban Continuum Code (9).
People and Places
We begin with a consideration of the relational role of contextual and compositional factors in independently producing variation in COVID-19 outcomes, and in bi-directionally impacting one another. The urban-suburban-rural divide reflects another important geographic level in which we can see both compositional and contextual determinants of inequities in COVID-19. Contextual factors associated with COVID-19 variation, such as the location of specific industries (e.g. agriculture, meat packing(1, 11)), overcrowding, political ideology (12), preexisting policy environments (13), and health care resources (14) differ substantially between urban, suburban, and rural places. Similarly, the composition of these geographies differs substantially: cities have younger populations than other geographies; larger immigrant populations live in urban and suburban areas than rural(15); rural residents have higher rates of chronic disease (16); and consistently rural areas vote conservative, suburbs increasingly lean democratic, and urban areas reliably vote democratic (17), although this may also reflect voter suppression and disengagement rather than composition (18).
O R I G I N A L U N E D I T E D M A N U S C R I P T
We further argue, following Cummins (4), that the composition of a place shapes the contextual conditions in which people reside. As an example, we consider the city of San Francisco, California. Since the 2000's, San Francisco has been home to an agglomeration of technology companies. Technology organizations quickly shifted to remote work environments (19), allowing many tech employees to work without risking COVID-19 exposure. The shifts in the composition of people with limited occupational exposure risk may have helped to prevent increases in infection rates in the Bay Area (19), despite early introduction of the disease in the region.
While much of the coverage on COVID-19 has focused on urban areas, both suburbs and rural areas have been severely impacted by the pandemic (8,20). In Figure 1 we show national differences in patterns.
Implications
Our analysis emphasizes the importance of the theoretical linkage between person and place, context and composition, and heterogeneity of impacts over time (4). Using the CDC analysis as a real-world example, we consider the implications of defining populations as isolated statistical entities defined exclusively by composition (5). While the CDC attempted to present a measure that considered differences in composition;
the measure oversimplified the complex dynamics of a country with geographic and compositional disparities, produced by 400 years of socioeconomic inequity and racism. Rather than attempting to weight away compositional differences, operationalizing a relational population approach would instead explicitly Identifying disparities often necessitates incorporation of complexity rather than attempts to control it away (24). Here we only approach questions of inequities by race/ethnicity, but measurement of inequities for other population groups (e.g., occupational categories or immigration status) should integrate how the composition of populations shape places, and contribute to how we conceptualize, define, and measure places (4,6). For example, if we were to try to understand how differences in governance relates to COVID-19 disparities (e.g.: do cities that are not pre-empted from keeping indoor dining closed have lower disparities?), we may need to consider geographical units that reflect differences in governance between states(13), rather than just urbanicity.
Future calculations of overall estimates of racial disparities in mortality burden, for COVID-19 and other disease monitoring, should incorporate the complexity of our inequitable history and present. To monitor inequities in cases and deaths at multiple levels and to ensure equitable access to testing, treatments, and vaccines, researchers and decision makers need longitudinal and more geographically granular data that allows for disaggregation. History tells us that the places and populations that bear the burden of social inequality are most vulnerable to adverse outcomes in times of emergency and crisis (25); our measures must also embody these preexisting inequities.
In their article, "A Geography of Risk: Structural Racism and COVID-19 Mortality in the United States," Zalla et al. present a critique of the Centers for Disease Control and Prevention's (CDC) approach to estimating provisional death counts and racial/ethnic inequities in Coronavirus disease deaths(1). The CDC estimates the percentage of COVID-19 deaths by race/ethnicity as the proportion of total deaths in a given county, compared to a weighted distribution of the county racial/ethnic population in which deaths have occurred. Complementing the methodological critique of the CDC approach by Cowger et al.(2), Zalla and
Zalla et al explicates the ways in which current and historical contextual and structural features of places, especially racial residential segregation, shape the composition of a population by determining where individuals live and work, and thereby determine risk of exposure to COVID-19(1). Segregation specifically shapes the housing availability and racial and socioeconomic composition of cities and suburbs, and available occupations by place, by stratifying housing and occupational opportunity that concentrates Black and Latinx populations in areas with few high-wage employment opportunities(10).
Figure 3 ,
3COVID-19 deaths by geography (urban, suburban, rural) and racial/ethnic classification (by county racial composition). While urban areas have had the highest absolute number of deaths, rates have generally been higher in suburban and rural areas. Specifically, mortality rates have been highest in suburban counties with a majority Native American population, followed by suburban and rural counties with a majority Black population and rural counties with a majority Hispanic population. Majority white areas had the lowest mortality rates within each geography and showed no clear urban-suburban-rural pattern. In summary, there is a disproportionate impact of COVID-19 mortality in suburban and rural communities of color.Time and People, Time and PlacesFigure 2shows rates of COVID-19 deaths over time by the majority racial composition of counties. The initial spike in COVID-19 death occurred in mixed and majority Black areas(21). While majority Hispanic and Native American/Alaska Native communities experienced among the lowest rates at the beginning of the pandemic, these grew substantially over the spring and summer to become the highest, peaking in the late Spring and late fall for majority Native American areas and in the summer for majority Hispanic areas.Overall, majority white communities have experienced among the lowest rates at all points other than recent increases in the late fall, when majority white communities had some of the highest rates. while the first wave of COVID-19 mostly affected urban areas, the second wave impacted urban, suburban, and rural areas similarly during the summer. However, the third wave in the fall had a disproportionate impact on suburban and rural areas.Time, Places, and PeopleFigure 4shows that, although the impact of the pandemic has been widespread, at most stages and across all geographies we see higher rates of impact for majority Black and Brown communities compared with majority white communities. The rise in mortality rates for majority white communities in the fall, as observed inFigure 2, is most likely due to increases in rural areas at this same time, which are disproportionately white. However, even within rural areas (Panel C), majority Black communities had some of the highest rates during the summer and early fall, followed by an increase in majority Hispanic and majority Native American rural communities. These communities had higher rates even during the late fall, when mortality rates in majority white rural communities started to increase. For mixed communities, patterns were similar to majority Black urban communities (Panel A), though continued to rise in suburban (Panel B) and rural areas over time.CDC Weighted Disparities and the Importance of Dynamic and Reciprocal Population DefinitionsCDC's weighted disparities analysis is a real-world example of the consequences of defining populations as isolated statistical entities with no intrinsic or extrinsic relationships(5). First, and according to CDC, the key impetus behind using weighted population distributions was that, "in April and May 2020, the majority of COVID-19 deaths in the U.S. occurred in urban areas that have a larger percentage of their populations that are non-Hispanic Black, non-Hispanic Asian, or Hispanic, and a smaller percentage that are non-Hispanic white."(3) While this is factually correct, it ignores, as posited byZalla(1), that this distribution of the population is not random, and that the initial impact in these urban areas may actually be partially related to their own composition. while CDC's analysis aimed at controlling for differences in the racial composition of urban areas versus suburban and rural areas, composition is dynamic and historically contingent. Over the past 20 years, the suburbs have increasingly become home to the non-white population, shifting the predominant patterns of Black and Brown cities and predominantly white suburbs produced by residential racial segregation(22). Due to gentrification, increasing immigration, and middle-class Black and Brown families choosing to (or being forced to) relocate to suburbs, by 2010 the suburbs were home to more than 50% of the non-white population and of all immigrants(23). These shifts suggest that the context and composition of suburban areas have shifted over the last 20 years, in ways that likely produce meaningful differences for rates of COVID-19, by changing many of the aforementioned contextual and compositional factors (e.g. housing conditions, political ideology, industry, racial/ethnic and age composition, etc.). In summary, current COVID-19 patterns are contingent on contemporary contextual and compositional factors that are themselves dependent on historical features of places and people. Treating populations as isolated statistical entities(5), or mere aggregations of individuals, obscures our understanding of COVID-19
examine place, people, and time effects and their interactions. While there are numerous complex qualitative and quantitative methodological approaches to integrate relational approaches into empirical analysis(4) we propose a simple strategy that recognizes complexity and is common to presenting : present multiple stratified analysisacross place, people, and time--alongside summary measures. For example, comparingFigure 3toFigure 4, we miss the rise in urban Hispanic rates without inclusion of geography; or comparingFigure 1to 3: we lose understanding of the important inversion inJuly between urban and rural/suburban areas in geographic concentration of COVID-19 deaths without a consideration of time. We do acknowledge that our very description, by grouping places by composition, is limited. This highlights another challenge of understanding inequities in COVID-19, the lack of readily available longitudinal data that allows for cross-examinations of population subgroups at different locations.
Figure 1 :Figure 2 :Figure 3 :Figure 4 :
1234COVID-19 Mortality Rates by Place (Geography) and Person (Racial/Ethnic Composition)in the US, cumulatively through December 31 st , 2020Legend: Black fill indicates majority Black counties, dark grey majority Hispanic counties, light grey majority Native American counties, white majority white counties, and striped mixed (COVID-19 Mortality Rates by Time and Person (Racial/Ethnic Composition) in the US, from January to December 2020Legend: Black line indicates majority Black counties, dark grey majority Hispanic counties, light grey majority Native American counties, dots majority white counties, and dashes mixed (no majority) counties.COVID-19 Mortality Rates by Place (Geography) and Time in the US, from January toDecember 2020Legend: Black line indicates urban, dark grey suburban, and light grey rural geographic regions.COVID-19 Mortality Rates by Place (Geography), Person (Racial/Ethnic Composition), and Time in the US, from January to December 2020Legend: Panel A displays urban, panel B displays suburban, and panel C displays rural geographic regions.Black line indicates majority Black counties, dark grey majority Hispanic counties, light grey majority Native American counties, dots majority white counties, and dashes mixed (no majority) counties.
. L C Zalla, C L Martin, J K Edwards, COVID-19Geography of Risk: Structural Racism. Zalla LC, Martin CL, Edwards JK, et al. A Geography of Risk: Structural Racism and COVID-19
Mortality in the United States. American Journal of Epidemiology. Mortality in the United States. American Journal of Epidemiology 2021.
Comparison of weighted and unweighted population data to assess inequities in coronavirus disease 2019 deaths by race/ethnicity reported by the US Centers for Disease Control and Prevention. T L Cowger, B A Davis, O S Etkins, JAMA network open. 372016933Cowger TL, Davis BA, Etkins OS, et al. Comparison of weighted and unweighted population data to assess inequities in coronavirus disease 2019 deaths by race/ethnicity reported by the US Centers for Disease Control and Prevention. JAMA network open 2020;3(7):e2016933-e.
Health Disparities: Race and Hispanic Origin. Notes. National Center for Health StatisticsAccessedNational Center for Health Statistics. Health Disparities: Race and Hispanic Origin. Notes. 2020. (https://www.cdc.gov/nchs/nvss/vsrr/covid19/health_disparities.htm#notes).(Accessed January 11th 2021).
Understanding and representing 'place'in health research: a relational approach. S Cummins, S Curtis, A V Diez-Roux, Social science & medicine. 659Cummins S, Curtis S, Diez-Roux AV, et al. Understanding and representing 'place'in health research: a relational approach. Social science & medicine 2007;65(9):1825-38.
Who and what is a "population"? Historical debates, current controversies, and implications for understanding "population health" and rectifying health inequities. N Krieger, The Milbank Quarterly. 904Krieger N. Who and what is a "population"? Historical debates, current controversies, and implications for understanding "population health" and rectifying health inequities. The Milbank Quarterly 2012;90(4):634-81.
Are neighborhoods causal? Complications arising from the 'stickiness' of ZNA. T A Glass, U Bilal, Soc Sci Med. 166Glass TA, Bilal U. Are neighborhoods causal? Complications arising from the 'stickiness' of ZNA. Soc Sci Med 2016;166:244-53.
An interactive web-based dashboard to track COVID-19 in real time. E Dong, H Du, L Gardner, The Lancet infectious. 20205Dong E, Du H, Gardner L. An interactive web-based dashboard to track COVID-19 in real time. The Lancet infectious diseases 2020;20(5):533-4.
They're Dying in the Suburbs: COVID-19 Cases and Deaths by Geography in Louisiana (USA). A Schnake-Mahl, U Bilal, preprintSchnake-Mahl A, Bilal U. They're Dying in the Suburbs: COVID-19 Cases and Deaths by Geography in Louisiana (USA) [preprint].
. Medrxiv, doi.org/10.1101/2020.10.28.20221341Medrxiv. 2020. (doi.org/10.1101/2020.10.28.20221341). Accessed February 18, 2021.
Rural-Urban Continuum Codes (RUCC). 18USDA, United States Department Of Agriculture Economic Research ServiceAccessed FebruraryUSDA, United States Department Of Agriculture Economic Research Service. Rural-Urban Continuum Codes (RUCC). 2013. (https://www.ers.usda.gov/data-products/rural-urban- continuum-codes.aspx). (Accessed Februrary 18, 2021).
Racial residential segregation: a fundamental cause of racial disparities in health. D R Williams, C Collins, Public health reports. 1165404Williams DR, Collins C. Racial residential segregation: a fundamental cause of racial disparities in health. Public health reports 2001;116(5):404.
Racial capitalism within public health: How occupational settings drive COVID-19 disparities. E S Mcclure, P Vasudevan, Z Bailey, American journal of epidemiology. McClure ES, Vasudevan P, Bailey Z, et al. Racial capitalism within public health: How occupational settings drive COVID-19 disparities. American journal of epidemiology 2020;
Partisan differences in physical distancing are linked to health outcomes during the COVID-19 pandemic. A Gollwitzer, C Martel, W J Brady, Nature human behaviour. 411Gollwitzer A, Martel C, Brady WJ, et al. Partisan differences in physical distancing are linked to health outcomes during the COVID-19 pandemic. Nature human behaviour 2020;4(11):1186-97.
Preemption and Its Impact on Policy Responses to COVID-19. M Treskon, B Docter, Urban InstituteTreskon M, Docter B. Preemption and Its Impact on Policy Responses to COVID-19. Urban Institute 2020.(https://www.urban.org/research/publication/preemption-and-its-impact-policy- responses-covid-19). (Accessed February 18, 2021).
Health Care In The Suburbs: An Analysis Of Suburban Poverty And Health Care Access. A S Schnake-Mahl, B D Sommers, Health Affairs. 3610Schnake-Mahl AS, Sommers BD. Health Care In The Suburbs: An Analysis Of Suburban Poverty And Health Care Access. Health Affairs 2017;36(10):1777-85.
What unites and divides urban, suburban and rural communities. K Parker, J M Horowitz, A Brown, Pew Research Center. Parker K, Horowitz JM, Brown A, et al. What unites and divides urban, suburban and rural communities. Pew Research Center 2018.( https://www.pewresearch.org/social- trends/2018/05/22/what-unites-and-divides-urban-suburban-and-rural-communities/). (Accessed February 18, 2021).
Continuing Challenges in Rural Health in the United States. S S Coughlin, C Clary, J A Johnson, Journal of environment and health sciences. 5290Coughlin SS, Clary C, Johnson JA, et al. Continuing Challenges in Rural Health in the United States. Journal of environment and health sciences 2019;5(2):90.
The Urban-Rural Gulf in American Political Behavior. J G Gimpel, N Lovin, B Moy, Political Behavior. 2020Gimpel JG, Lovin N, Moy B, et al. The Urban-Rural Gulf in American Political Behavior. Political Behavior 2020:1-26.
The Role of Rural Communities of Color in the 2020 Election. O Ajilore, Center For American ProgressAjilore O. The Role of Rural Communities of Color in the 2020 Election. Center For American Progress, 2020. (https://www.americanprogress.org/issues/economy/reports/2020/12/22/494188/role-rural- communities-color-2020-election/). (Accessed February 18, 2021).
What the San Francisco Bay Area Can Teach Us About Fighting a Pandemic. J C Kang, New Yorker. Kang JC. What the San Francisco Bay Area Can Teach Us About Fighting a Pandemic. New Yorker. (https://www.newyorker.com/news/california-chronicles/what-the-san-francisco-bay-area-can- teach-us-about-fighting-a-pandemic). (Accessed February 18, 2021).
Impacts of the COVID-19 pandemic on rural America. J T Mueller, K Mcconnell, P B Burow, Proceedings of the National Academy of Sciences. 1181Mueller JT, McConnell K, Burow PB, et al. Impacts of the COVID-19 pandemic on rural America. Proceedings of the National Academy of Sciences 2020;118(1).
The Changing Geography of COVID-19 in the. B Jones, J Kiley, Pew Research. Jones B, Kiley J. The Changing Geography of COVID-19 in the U.S.: Pew Research 2020. ( https://www.pewresearch.org/politics/2020/12/08/the-changing-geography-of-covid-19-in-the-u- s/). (Accessed February 18, 2021).
The Color of Law: A Forgotten History of How Our Government Segregated America. R Rothstein, Liveright PublishingNew York, NYRothstein R. The Color of Law: A Forgotten History of How Our Government Segregated America. New York, NY: Liveright Publishing; 2017.
State of Metropolitan America: On the Front Lines of DemographicTransformation. Brookings Institution Metropolitan Policy ProgramBrookings Institution Metropolitan Policy Program. State of Metropolitan America: On the Front Lines of DemographicTransformation. 2010.(https://www.brookings.edu/wp- content/uploads/2016/06/metro_america_report.pdf). (Accessed February 18, 2021).
Social Class and Child Health: Our Complexity Complex. T A Glass, Landale NS, McHale SM, Booth ASpringerNew York, NY; New YorkFamilies and Child HealthGlass TA. Social Class and Child Health: Our Complexity Complex. In: Landale NS, McHale SM, Booth A, eds. Families and Child Health. New York, NY: Springer New York, 2013:143-54.
Historical Insights on Coronavirus Disease 2019 (COVID-19), the 1918 Influenza Pandemic, and Racial Disparities: Illuminating a Path Forward. L Krishnan, S M Ogunwole, L A Cooper, Annals of internal medicine. 1736Krishnan L, Ogunwole SM, Cooper LA. Historical Insights on Coronavirus Disease 2019 (COVID- 19), the 1918 Influenza Pandemic, and Racial Disparities: Illuminating a Path Forward. Annals of internal medicine 2020; 173(6):474-481.
| [
0.006431922782212496,
0.009452556259930134,
0.03361392766237259,
0.040203411132097244,
0.0972965881228447,
-0.008572302758693695,
-0.1133100762963295,
0.10822491347789764,
0.0700806975364685,
0.018549110740423203,
0.048178400844335556,
0.01875406503677368,
0.029733849689364433,
0.041724249... |
Type Ia supernovae and the formation history of early-type galaxies
2002
Ignacio Ferreras
Physics Dept
Denys Wilkinson Building, 1 Keble RoadOX1 3RHOxfordUnited Kingdom
Joseph Silk
Physics Dept
Denys Wilkinson Building, 1 Keble RoadOX1 3RHOxfordUnited Kingdom
Type Ia supernovae and the formation history of early-type galaxies
Mon. Not. R. Astron. Soc
0002002Submitted March 18, 2002; Revised June 11, 2002; Accepted July 17, 2002arXiv:astro-ph/0207632v2 29 Printed 2 November 2018 (MN L A T E X style file v1.4)galaxies: evolution -galaxies: abundances -galaxies: stellar contentgalaxies: elliptical and lenticularcD
Using the standard prescription for the rates of supernovae type II and type Ia, we compare the predictions of a simple model of star formation in galaxies with the observed radial gradients of abundance ratios in a sample of early-type galaxies to infer the relative contribution of each type of supernova. The data suggests a correlation between the fractional contribution of Type Ia to the chemical enrichment of the stellar populations (1 − ξ) and central velocity dispersion of order 1 − ξ ∼ −0.16 log σ 0 + 0.40, so that the type Ia contribution in stars ranges from a negligible amount in massive (σ 0 ∼ 300 km s −1 ) galaxies up to 10% in low-mass (∼ 100 km s −1 ) elliptical galaxies. Our model is parametrized by a star formation timescale (t SF ) which controls the duration of the starburst. A correlation with galaxy radius as a power law (t SF ∝ r β ) translates into a radial gradient of the abundance ratios. The data implies a wide range of formation scenarios for a simple model that fixes the luminosity profile, ranging from inside-out (β = 2), to outside-in formation (β = −1), as is consistent with numerical simulations of elliptical galaxy formation. An alternative scenario that links t SF to the dynamical timescale favours inside-out formation over a smaller range 0.4 < β < 0.6. In both cases, massive galaxies are predicted to have undergone a more extended period of star formation in the outer regions with respect to their low-mass counterparts.
INTRODUCTION
Type Ia supernovae (SNIa) describe stellar explosions whose spectra show lines of elements or intermediate mass such as silicon, and of the iron group, but no hydrogen lines. They currently occupy a very special place in cosmology since they can be used as standard candles. Even though their luminosities span an order of magnitude, empirical correlations between their absolute magnitude and the shape of their light curves can be used in order to determine distances (Phillips 1993) in an analogous way to classical Cepheids. Furthermore, the absolute luminosity of SNIa is orders of magnitude brighter than variable stars, enabling us to observe them at high redshift. This is a tool currently being used to constrain the cosmological parameters (e.g. Perlmutter et al. 1999;Riess et al. 1998). However, SNIa also play a very important role in the process of galactic chemical enrichment since they contribute a large amount of iron to the interstellar medium (Thielemann, Nomoto & Yokoi 1986). In fact Type Ia supernovae might even be the main producers of iron in the Universe ; how-⋆ ferreras,silk@astro.ox.ac.uk ever see Gibson, Loewenstein & Mushotzky 1997). The observed properties of SNIa's suggest a binary model in which at least one of the stars is a white dwarf that reaches the Chandrasekhar limit (∼ 1.4M⊙) by accretion or by merging with another white dwarf. The timescale for the explosion is thereby limited by the lifetimes of stars which end up as white dwarfs, i.e. with masses M < ∼ 8M⊙. This implies that Type Ia's can be observed long after star formation subsided. Indeed, all supernovae observed in early-type galaxies -which feature no ongoing star formation -are Type Ia, whereas late-type galaxies display a mixture of Type Ia and Type II supernovae (Cappellaro et al. 1997) On the other hand, Type II supernovae (SNII) show hydrogen lines in their spectra and arise from the core collapse of a single, massive (M > ∼ 8M⊙) star at the end of its lifetime, which occurs between 1 − 50 Myrs after the core hydrogen burning phase started. Hence, the timescales of either type of supernovae are remarkably different. Furthermore, the yields of chemical elements are also in sharp contrast, since SNIa produce much more iron than SNIIs, so that stars born during the first phases of star formationwhen the contribution from SNIa to the interstellar medium was negligible -display an enhancement of α elements over iron, with respect to the younger generations of stars, such as the Sun, which are born in an environment polluted by both types of supernovae.
Observations of radial gradients in the colours (Franx, Illingworth & Heckman 1989;Peletier et al. 1990;Jørgensen, Franx & Kjaegaard 1995) and line indices (González 1993;Davies, Sadler & Peletier 1993;Peletier et al. 1999) in elliptical galaxies show gradients, being mostly redder and more metal rich at their centres, although some early-type galaxies display blue cores (Menanteau, Abraham & Ellis 2001). Broadband photometry has been a technique repeatedly used to infer the star formation history of galaxies notwithstanding the age-metallicity degeneracy (Worthey 1994), which prevents us from getting a well-defined picture of galaxy formation using colours alone. A combined analysis of line indices seem to break the degeneracy since their age and metallicity dependence can be rather different (Kuntschner 2000;Trager et al. 2000aTrager et al. , 2000b. Abundance ratios represent an alternative observable since the timescales for SNIa and SNII are remarkably different. Giant early-type galaxies feature an overabundance of α elements over iron (Peletier 1989;Worthey, Faber & González 1992;Trager et al. 2000a;Kuntschner 2000), indicative of a short duration of the star formation stage, so that mostly SNII contribute to the metallicity of the stellar component.
This has been used in several models of galaxy formation in order to constrain the star formation history of galaxies. Matteucci (1994) analysed the observed [Mg/Fe] ratios in ellipticals to constrain the star formation history to timescales shorter than 0.1 Gyr. Furthermore, the trend of [Mg/Fe] with galaxy mass was used to imply either an increasing star formation efficiency with galaxy mass, or a top-heavy initial mass function, so that more massive stars were formed in ellipticals compared to a more quiescent environment such as in a disk galaxy. A detailed analysis of abundance ratios in metal-poor stars is a valuable tool for determining the star formation history in the solar neighbourhood (Gratton et al. 2000), and this can be extended to stellar populations in globular clusters. In a recent analysis of abundance ratios in a sample of six red giant stars in the ω Cen cluster, Pancino et al. (2002) found evidence for the contribution of SNIa to the composition of younger, more metal rich red giants.
In this paper we explore the radial gradients observed in abundance ratios such as [Mg/Fe] in elliptical galaxies as a function of the star formation timescale. The relative contribution from SNIa and SNII can be compared with observations to infer the formation process of the stellar components, enabling us to connect the star formation history and the dynamical history of early-type galaxies. In §2 and §3 we describe the model used to predict the rates of either type of supernovae and their contribution to chemical enrichment. §4 describes our model predictions and compares them to observed data. Finally, in §5 we discuss the implications of the comparison between our simple model and the observed data.
RATES OF TYPE IA AND TYPE II SUPERNOVAE
The progenitors of type Ia supernovae are still a matter of debate. The most common candidates are either the double degenerate model (Iben & Tutukov 1984) in which two C-O white dwarfs merge, reaching the Chandrasekhar mass and exploding by C deflagration, and the single degenerate model (Whelan & Iben 1973) comprising a close binary system made of a nondegenerate star and a C-O white dwarf which accretes material from the other component, reaching the Chandrasekhar mass and triggering C deflagration. The negative result in the search for close binary systems made up of two massive white dwarfs in a sample of 54 white dwarfs (Bragaglia et al. 1990) hints at the single degenerate model as the most plausible one, which is the one we will assume henceforth. The ESO SNIa progenitor survey, which will use UVES/VLT (Koester et al. 2001) on a sample of 1,500 white dwarfs will clarify this point. In order to estimate the rates of type Ia supernovae, we follow the prescription of Greggio & Renzini (1983), recently reviewed by Matteucci & Recchi (2001). The rate can be written as a convolution of the initial mass function (IMF) over the mass range that can generate a type Ia supernova. The lower mass limit is MBm = 3M⊙ in order to generate a binary with a white dwarf which will reach the Chandrasekhar limit. The upper mass limit is MBM = 16M⊙ so that neither binary undergoes core collapse. The rate is thus:
RIa(t) = A 16M ⊙ 3M ⊙ dmφ(m) µmax µm dµ ′ f (µ ′ )ψ(t − τm 2 ),(1)
where mt = max(3M⊙, m(t)) and m(t) is the mass of a star whose lifetime is t, whereas τm 2 is the lifetime of the nondegenerate companion, with mass m2. f (µ) is the fraction of binaries with a mass fraction µ ≡ M2/MB, where M2 and MB are the masses of the secondary star and the binary system, respectively. The range of integration goes from µm = max(m2/m, 1−8M⊙/m), to µmax = 0.5. The analysis of Tutukov & Yungelson (1980) on a sample of about 1000 spectroscopic binary stars suggests that mass ratios close to µ = 1/2 are preferred, so that the normalized distribution function of binaries can be written:
f (µ) = 2 1+γ (1 + γ)µ γ ,(2)
as suggested by Greggio & Renzini (1983), and we adopt the value of γ = 2. The normalization constant A is constrained by the ratio between type Ia and type II supernovae in our Galaxy that best fits the observed solar abundances. We use the result of Nomoto, Iwamoto & Kishimoto (1997), namely RIa/RII = 0.12 to find A = 0.05. The rate of type II supernovae is also given as an integral of the star formation convolved with the IMF, in this case over the mass range expected for the precursors of single component supernovae, i.e. 8 < M/M⊙ < 50. Here we adopt 50M⊙ as the upper mass cutoff. We use throughout the paper either a Salpeter (1955) or a Scalo (1986) IMF.
RII (t) = 50M ⊙ 8M ⊙ dmφ(m)ψ(t − τm),(3)
where we have neglected the contribution from binaries to the IMF over this mass range. Figure 1 shows the rates of either type of supernovae for a generic star formation history given by a gaussian profile with a width of tSF = 0.1 Gyr (left panels) or 1 Gyr, respectively. The shape of the curve plotting the rate of type IIs is nearly identical to the star formation rate given the very short lifetimes of massive stars that undergo core collapse. Hence, the rate of this type of supernovae is negligible a few Myr after the star formation has ceased. On the other hand, the longer timescales of the nondegenerate companions in type Ias imply that these supernovae start contributing significantly to the chemical enrichment of the ISM a few hundred Myr after the main burst of star formation. This effect is more extreme in sharply peaked bursts of star formation although its contribution to chemical enrichment is only important for the interstellar medium and not so much for the metallicities of the stellar populations unless later bursts of star formation allow the ejected metals from SNIas to be locked into subsequent generations of stars.
CHEMICAL ENRICHMENT
The supernova rates allow us to infer the amount of metals ejected to the interstellar medium. We target magnesium and iron as the main elements which should be observed to discern the contribution between SNIa and SNII. Magnesium is one of the α elements, which are those that can be obtained from the reaction of C and O with helium nuclei. These elements are: Ne, Mg, Si, S. The solar abundance of these elements is slightly enhanced with respect to the mean (given by some average metallicity Z). Another family of elements -the so-called iron-peak elements, which include Fe and Co -are less abundant with respect to Z. Notice that the amount of iron-peak elements contributes only a small fraction to the total metallicity (8% at solar abundance), so that changing the abundance of Fe by a large amount does not affect significantly the average metallicity. Hence, it would be more correct to think of a depression in Fe-peak elements in solar abundances, rather than an enhancement of α elements at the centres of elliptical galaxies (Trager et al. 2000b).
The yields from SNIa are taken from the single degenerate model W7 of Thielemann et al. (1986), which assumes a progenitor made up of a 1M⊙, C+O white dwarf with equal parts of 12 C and 16 O, with an accretion rate of 4 × 10 −8 M⊙ yr −1 . The yields from SNII are taken from Thielemann, Nomoto & Hashimoto (1996) for a range of progenitor masses. The stellar initial mass function (IMF) is used in order to take a weighted-average of the yields with respect to mass. The yields used in this paper are shown in Table 1. Notice that a very significant amount of iron is produced in SNIa with respect to the α elements. The mass contained in O-, Ne-and C-burning shells is too small compared with the mass in the Si-burning zone. This implies SNIa ejecta are dominated by the products of complete and incomplete Si-burning, i.e. a higher iron yield compared to the ejecta from core-collapse supernovae. However, this is still debatable because the yields may depend rather sensitively on the initial metallicity. For instance, assuming an average metallicity of 0.5Z⊙ over the star formation history of the galaxy will lead to a total reduction of 25% in the amount of Fe ejected from SNIa (Thielemann et al. 1986).
In this paper we do not consider the contribution of low and intermediate-mass stars (M ≤ 8M⊙) to chemical enrichment. We focus on the contribution from either type of supernova to the star formation history in early-type galaxies through the analysis of Mg and Fe. These elements are not produced in stars which do not undergo core-collapse, except for very small traces of Mg in intermediate mass stars (Marigo, Bressan & Chiosi 1996), which can be neglected for our analysis. However, one could argue that the metallicity dependence of the yields from both supernova types will introduce a dependence on the contribution to chemical enrichment from lower mass stars. We do not consider this dependence in our models but we emphasize this point as a possible factor to improve upon as more developed theoretical models of supernova explosions become available.
Another important factor that needs further work is the "starting" abundance ratios one would expect from Population III stars, the very first stars formed. They are assumed to have a very different IMF, so that their masses are much higher than subsequent generations of stars. The study of the yields from this population is still under way, but some preliminary modelling of high-mass helium cores (64 − 133M⊙) suggests the yields present solar abundances for nuclei with even nuclear charge (Si, S, Ar) and signif-icant defficiencies in odd-charge nuclei (Na, Al, P) (Heger & Woosley 2002). If the pre-enrichment from Population III stars is important, one would have to consider three different contributors to the abundance of Mg and Fe.
Assuming only two contributors, namely SNIa and SNII, we can find the correlation between [Mg/Fe] and the relative contribution of each type of supernova, quantified by the parameter
ξ ≡ RII RII + RIa ,(4)
where RIa and RII are the rates of SNIa and SNII, respectively. Figure 2 Scalo 1986). The data points are from the detailed analysis of early-type galaxies in the Fornax cluster by Kuntschner (2000), and from the sample of Trager et al. (2000a), evaluated at two radial positions, r = Re/8 and Re/2. The translation from line indices to metal abundances is done by matching the data against a grid of simple stellar populations over a range of ages and metallicities. The data points are plotted as a function of central velocity dispersion (σ0, top axis), which has been chosen so that the model prediction -plotted against (1−ξ) -gives a good fit to the data. This implies a correlation of order:
(1 − ξ) ∼ −0.16 log σ0 + 0.43.
The vertical line at 1 − ξ = 0 corresponds to the prediction for a model in which no SNIa contribute to the enrichment of the stellar populations. Hence, the contribution of SNIa range from a negligible amount for massive galaxies (σ0 ∼ 300 km s −1 ) up to 10% for low-mass elliptical galaxies (σ0 ∼ 100 km s −1 ). The timescales associated to the triggering of SNIa imply star formation occured in a very short burst in massive ellipticals, whereas low-mass galaxies have a slightly more extended period of star formation. This can be accomodated in the framework of hierarchical clustering if we assume that the latest merging stages of massive ellipticals do not give rise to star formation but, rather, involve the merging of the stellar and gas component. Solar abundances are obtained for a contribution of SNIa to the total rate (1 − ξ) of order 10%, which should not come as a surprise since this is the constraint used in order to compute the proportionaly constant A described in §2.
ABUNDANCE GRADIENTS
Observations of colours (Franx et al 1989;Peletier et al. 1990;Jørgensen et al. 1995) and line indices (González 1993;Davies et al. 1993;Peletier et al. 1999) in elliptical galaxies show radial gradients, being redder and richer in metals at their centres. The observed spectral indices display a metallicity gradient of ∆[Fe/H]/∆ log R = −0.2 ± 0.1 (Davies et al. 1993), consistent with the observed colour gradients. A metallicity gradient can be directly linked to the standard picture of galaxy formation by the dissipative collapse of a gas cloud. Carlberg (1984) analyzed such models with an N-body code, and predicted abundance gradients around −0.5 in massive galaxies, flattening towards zero slope in lower mass galaxies. Recent merging events in massive early- type galaxies will dilute any radial signature from an earlier monolithic collapse process, thereby flattening the slope (White 1980;Mihos & Hernquist 1994). Hence, abundance gradients allow us to quantify the degree to which hierarchical clustering has contributed to the formation of galaxies.
We assume a simple model with spherical symmetry and a radially-dependent star formation efficiency. The standard model of star formation assumes a power-law dependence between the star formation rate (ψ) and the gas density (ρg; Schmidt 1963), namely:
ψ(t) = C eff ρ n g (t) ∝ exp(−t/tSF),(6)
where the constant of proportionality (C eff ) is the star formation efficiency, and the exponential function is the solution for a linear Schmidt law (n = 1), in which the star formation timescale tSF can be written as a function of the efficiency timescale (τ eff ∝ 1/C eff ) and the gas infall timescale (τ f ) as:
1 tSF = 1 τ eff + 1 τ f .(7)
Star formation is known to take place in clouds of molecular hydrogen. Cloud-cloud collisions contribute to the collapse, cooling and subsequent formation of stars. In this simple scenario, we would expect the star formation efficiency to be proportional to the frequency of cloud-cloud collisions, which should scale with the number density of clouds. Hence, the gas density profile traces the star formation efficiency, so that at the centre the star formation timescale should be shorter than in the outer regions. In this scenario tSF is a monotonically increasing function with radius. We assume a generic star formation history described by a gaussian function with a width given by the star formation timescale (tSF), which is left as a free parameter. The peak occurs at a time 2×tSF and we assume an age of the Universe of 12 Gyr. Figure 3 shows the predicted relative abundances of this simple model as a function of tSF for both IMFs described above and for a set of ages: 0.5, 1, 5 and 11 Gyr. The number in parenthesis gives the slope of the gradient for both IMFs. It is beyond the scope of this paper to infer a proper functional dependence of the star formation timescale with radius. Hence, we will just assume a generic power-law dependence:
tSF ∝ r β .(8)
We find that the predicted abundance radial gradient for old stellar ages is ∆[Mg/Fe]/∆r ∼ −0.15β. In order to compare the model and the observations, we project the 3D radial coordinate (r) on to a 2D radius (R) using a generic luminosity profile:
L(< r) ∝ r γ → L(r) ∝ r γ−3 .(9)
By projecting the volume distribution on to a surface, we can compare the observed slope a ≡ ∆ [Mg/Fe]/∆ log R with the model prediction:
a = γ − 2 − 0.15β.(10)
Using the deprojected function presented in Hernquist (1990), which gives a 2D de Vaucouleurs profile, we can choose γ = 2. This value also matches a NFW profile (Navarro, Frenk & White 1997) for radii shorter than the core radius. In this case, the slope of the correlation between radius and star formation timescale can be written:
β(fixed γ) = − a 0.15 .(11)
On the other hand, we can fix β much in the same way as most semi-analytic modellers do (e.g. Baugh et al. 1998;Kauffmann, White & Guiderdoni 1993) so that the star formation efficiency (1/tSF) scales with the dynamical timescale r 3 /GM (< r). If we impose a mass-to-light ratio that does not change with radial distance -to be expected in galaxies formed in short duration bursts -we can use equation (9) to write M (< r) ∝ r γ , which implies:
β = 3 − γ 2 ,(12)
and in turn implies:
γ = a + 2.225 1.075 .(13)
Our model assumes that the gradient of the abundance ratios is caused by a formation scenario with different burst lifetimes, which depend on the distance to the centre. One could argue that a large spread of efficiencies in different regions of elliptical galaxies would result in a rather large age spread. However, the age-sensitive Balmer absoption index Hβ does not show any correlation with radial distance (Davies et al. 1993). This implies elliptical galaxies do not have a wide age spread in their stellar populations. Figure 4 shows that even though we consider a large range of star formation timescales, our model is in agreement with the data. We plot in this figure the mass-weighted age of the stellar component as a function of galaxy age for three different star formation timescales. The inset gives the predicted absorption in Hβ as a function of stellar age for simple stellar populations with three different metallicities from the latest population synthesis models of Bruzual & Charlot (in preparation). One can see that after 3 − 4 Gyr, it is virtually impossible to determine the stellar ages. This is the age shown as a dashed horizontal line in the figure, which implies that for galaxy ages of 8 Gyr, we can explore a range of star formation timescales up to tSF ∼ 2 Gyr and still reproduce the observed lack of correlation between radius and Balmer index.
DISCUSSION
Our model links the abundance ratios to the star formation timescale, which cannot be directly observed. Instead, the data available give radial gradients. A simple power law, as described in equation (8), can be used in order to throw light on the possible correlation between the infall rate or the star formation efficiency and the dynamical properties of the galaxy. Figure 5 compares the observed radial gradients with the predicted ones, as a function of [Mg/Fe]. The hollow squares represent the data from Trager et al. (2000a), measured at two projected radial positions: Re/8 and Re/2, which enables us to determine a gradient. A clear trend is seen towards positive gradients in more [Mg/Fe]-enhanced (i.e. more massive) galaxies. The other data points come from the compilation of Kobayashi & Arimoto (1999) from which we selected the work of González (1993, GON); Davies et al. (1993, DSP), and Carollo et al. (1993, CDB) estimated by the authors of the compilation to have the most reliable data. There is a very large scatter in this compilation, with a wide range of slopes, both negative and positive. In agreement with the data from Trager et al. (2000a), a correlation can be seen so that galaxies with positive slopes tend to have the largest super-solar abundances, which correspond to the most massive galaxies as seen in figure 2. The solid line gives a least-squares fit to the data from Trager et al. (2000a). The dashed line also shows a similar trend in the compilation of Kobayashi & Arimoto (1999). Estimating abundance ratios from line indices is still a very delicate issue especially because of the difficulty in finding a suitable set of stars for calibration. Hence, a theoretical approach is called for, using the computations of Tripicco & Bell (1995), who recomputed all of the Lick/IDS spectral indices from a grid of theoretical spectra and atmospheres with varying abundance ratios. The response functions to nonsolar ratios is used to correct the standard population synthesis models of Worthey (1994), calibrated for solar abundance ratios. The uncertainties in such translation frmo abundances to line in- Figure 5. Observed abundance gradients estimated from the measurements of Trager et al. (2000a;TRG; hollow squares) at Re/8 and Re/2. A typical error bar is shown for illustration. The solid line is a linear squares fit to this data. A rough estimate of [Mg/Fe] gradients from Kobayashi & Arimoto (1999) is also shown. The data points from this compilation correspond to the sample of González (1993, GON); Davies et al. (1993, DSP); and Carollo et al. (1993, CDB). The trend clearly seen in the data from Trager et al. (2000a) as well as hinted at by the void in the lower right corner of the data from Kobayashi & Arimoto (1999), and illustrated by the dashed line, can be interpreted as a hint towards a correlation between galaxy mass (which scales with [Mg/Fe]) and the lower limit of the gradient. dices is discussed in Trager et al. (2000a), and an error bar including these uncertainties is shown in figure 5.
A negative gradient implies an inside-out formation process, which is suggestive of a monolithic collapse scenario, with gas falling towards the centres of dark matter halos, with a gas density profile that decreases outwards and a temperature that decreases inwards, thereby generating a process of star formation that starts at the centre and spreads outwards. On the other hand, recent TreeSPH numerical simulations of galaxy formation (Sommer-Larsen, Gotz & Portinari 2002) find early-type galaxies (both ellipticals and lenticulars) in which star formation proceeds in the opposite way, namely outside-in, mainly triggered by merging. Furthermore, recent observations of field spheroidals in the Hubble Deep Field (Menanteau et al. 2001) show blue cores, result which is currently interpreted as secondary bursts of star formation, but which could be an indication of an outside-in formation process, which implies a positive gradient.
In the light of these data, we infer a varying correlation between the star formation timescale (tSF) and galaxy radius. A simple approach, fixing γ as in equation (11) gives a slope for this correlation in the range −1.3 < β < 2. A better approximation, relating β and γ through the dynamical timescale, assuming a fixed mass-to-light ratio (12) gives 0.4 < β < 0.6 with a mass or luminosity profile slope of 1.8 < γ < 2.2. The higher values of γ correspond to positive gradients in the abundance ratio.
The scatter is rather large, and it can only imply a very weak correlation between β or γ and some dynamical parameter such as central velocity dispersion or mass. This scatter gives another hint of merging as the major mechanism in the assembly process of early-type systems. In a purely monolithic collapse scenario, one would expect a well-defined correlation between the dynamical timescale and the star formation timescale, in such a way that most of the early star formation would occur at the centre. The void in the lower right corner of figure 5 (illustrated by the thick dashed line) shows that we can infer a correlation between [Mg/Fe] (or galaxy mass as shown in Figure 2) and a lower limit to the gradient. This can be interpreted as monolithic collapse being possible only in low mass systems. Higher mass galaxies must be assembled through merging. We emphasize here that the inside-out versus outside-in classification may be an oversimplification. Depending on the simple model we choose -i.e. fixed luminosity profile, as in (11), or correlating β with the dynamical timescale, as in (12), massive galaxies give respectively real outside-in star formation (β < 0) or a shallower slope for the correlation between star formation timescale and radius. In either case, the correlation suggested by the dashed line in figure 5 hints at more star formation in the outskirts of massive galaxies compared to low mass systems during the major stage of star formation.
It is worth mentioning that the slope of the abundance ratios is a more robust estimator than the absolute abundance. The latter is strongly dependent on the amount of gas ejected in outflows, which is an important mechanism in early-type galaxies as hinted at by the mass-metallicity relation (Arimoto & Yoshii 1987;Ferreras & Silk 2001), whereas the slope would depend on the scaling of the outflows with radial distance, which should be similar to the scaling of the star formation efficiency and infall timescale, thereby reducing the effect of outflows on the slope.
The radial gradients in abundance ratios represent an alternative way of studying the universality of the IMF, compared to analyses of the metallicities of local stars or the intracluster medium (Wyse 1997). Figure 3 shows that a nonuniversal IMF would translate into a slope change of the abundance ratio [Mg/Fe]. For instance, if we expect a topheavy IMF in environments with a high star formation rate (i.e. with a short tSF) then the correlation between [Mg/Fe] and star formation timescale should be steeper. However, this calls for a more detailed model which is beyond the scope of this paper. We have also neglected the effect of early galactic winds which could eject α-enhanced material out of the galaxy. A correlation of these winds with the local escape velocity could explain the observed radial gradient of Mg abundance in ellipticals (Martinelli, Matteucci & Colafrancesco 1998).
The model presented here relies on the fact that we understand the mechanisms that trigger SNIa and we are able to predict their rates or at least their ratio with respect to SNII. Short bursts of star formation imply that most of the contamination from SNIa will go to the ISM and not so much to the stellar component. Hence, we expect gas in ellipticals to have solar abundance ratios. There has been a long controversy over this point. The study of ASCA observations of a few clusters hinted at a significant SNIa contamination of the gas in rich clusters . However, Gibson et al. (1997) showed that a different calibration could invalidate this hypothesis. Arimoto et al. (1997) even raised the doubt of whether abundance estimates using the standard iron L-line complex in X-rays is giving wrong metallicities. The latest analysis of six early-type galaxies in Virgo using ROSAT and ASCA observations (Finoguenov & Jones 2000) seem to agree with a high iron content, i.e. an important contribution from SNIa to the enrichment of the ISM in elliptical galaxies.
In this paper, we conclude that a simple treatment of the abundance ratios allows us to infer the star formation history and its connection to the dynamical formation history. The data seems to rule out a monolithic or secular formation scenario for the stellar component of massive ellipticals. On the other hand, the large scatter in the slope of the radial dependence of [Mg/Fe] in low-mass galaxies implies both a merging and a monolithic "mechanism" should be invoked for these systems. A combined analysis of abundance ratios both in the stellar populations and in the interstellar medium will enable us to explore the connection between these two histories, and to quantify the importance of merging events both in the star formation and dynamical histories of early-type galaxies.
ACKNOWLEDGMENTS
IF is supported by a grant from the European Community under contract HPMF-CT-1999-00109. It is a pleasure to thank Rosie Wyse and Scott Trager for very useful comments, Jesper Sommer-Larsen for his latest simulations of galaxy formation, and Harald Kuntschner for making available his Fornax cluster data. The anonymous referee is acknowledged for useful comments and suggestions.
Figure 1 .
1Relative contribution (top) and rates (bottom) of type Ia and type II supernovae for a generic star formation history described by a gaussian function peaked at 3 Gyr with a star formation timescale of t SF 0.1 (left) and 1 Gyr, respectively.
Figure 2 .
2Contribution from SNIa to chemical enrichment. (1−ξ) denotes the fractional contribution to the total supernova rate from SNIa, so that 1 − ξ = 0 represents a pure contribution from core-collapse supernovae. The data points are fromTrager et al. (2000a; T00), evaluated at Re/8 (filled squares) and Re/2 (hollow circles), and fromKuntschner (2000; K00). The observed data are plotted against central velocity dispersion (top axis). The model prediction is compatible with the data for a linear correlation between central velocity dispersion and SNIa contribution such as: (1 − ξ) = −0.16 log σ 0 + 0.43. The steeper slope of the Scalo IMF at the bright end implies a lower contribution from high mass stars (M > ∼ 20M ⊙ ), which results in a lower enhancement.
Figure 3 .
3[Mg/Fe] profile as a function of the star formation timescale (t SF ) which parametrizes the generic star formation history used in this paper. Several curves are given for different ages of the galaxy: 0.5, 1, 5 and 11 Gyr. The numbers in parenthesis give the slope of the profile (∆[Mg/Fe]/∆ log t SF ) for an age of 11 Gyr.
Figure 4 .
4Mass-weighted age of the stellar component as a function of galaxy age for our generic star formation history. The inset shows the predicted equivalent width of Hβ for several metallicities (from the top Z/Z ⊙ = {0.5,1, and 2}) using the latest population synthesis models of Bruzual & Charlot (in preparation). Mass-averaged ages older than t M > ∼ 3 Gyr (arrow) cannot be discriminated using Balmer indices.
TABLE 1 :
1Supernovae yields (in M ⊙ )Type
Mg
α
Fe
[α/Fe]
SNIa
0.016
0.438
0.742
−1.33
SNII(Salpeter)
0.122
3.177
0.094
+0.43
SNII(Scalo)
0.102
2.663
0.105
+0.30
c 2002 RAS, MNRAS 000, 1-??
. N Arimoto, Yoshii, A& A17323Arimoto, N. & Yoshii, 1987, A& A, 173, 23
. N Arimoto, K Matsushita, Y Ishimaru, T Ohashi, A Renzini, ApJ. 477128Arimoto, N., Matsushita, K., Ishimaru, Y., Ohashi, T. & Renzini, A. 1997, ApJ, 477, 128
. C M Baugh, S Cole, C S Frenk, C G Lacey, ApJ. 498504Baugh, C. M., Cole, S., Frenk, C. S. & Lacey, C. G. 1998, ApJ, 498, 504
. A Blagaglia, L Greggio, A Renzini, S Odorico, ApJ. 36513Blagaglia, A., Greggio, L., Renzini, A. & d'Odorico, S. 1990, ApJ, 365, L13
. E Cappellaro, M Turatto, D.-Yu Tsvetkov, O S Bartunov, C Pollas, R Evans, M Hamuy, A&A. 322431Cappellaro, E., Turatto, M, Tsvetkov, D.-Yu., Bartunov, O. S., Pollas, C., Evans, R. & Hamuy, M. 1997, A&A, 322, 431
. R G Carlberg, ApJ. 286403Carlberg, R. G. 1984, ApJ, 286, 403
. C M Carollo, I J Danzinger, L Buson, MNRAS. 265553Carollo, C . M., Danzinger, I. J. & Buson, L. 1993, MNRAS, 265, 553
. R L Davies, E M Sadler, R F Peletier, MNRAS. 262650Davies, R. L., Sadler, E. M. & Peletier, R. F. 1993, MNRAS, 262, 650
. I Ferreras, J Silk, ApJ. 557165Ferreras, I. & Silk, J. 2001, ApJ, 557, 165
. A Finoguenov, C Jones, ApJ. 539603Finoguenov, A. & Jones, C. 2000, ApJ, 539, 603
. D Fisher, M Franx, G Illingworth, ApJ. 459110Fisher, D., Franx, M. & Illingworth, G. 1996, ApJ, 459, 110
. M Franx, G Illingworth, T Heckman, AJ. 98538Franx, M., Illingworth, G., Heckman, T. 1989, AJ, 98, 538
. B K Gibson, M Loewenstein, R F Mushotzky, 290623MN-RASGibson, B. K., Loewenstein, M. & Mushotzky, R. F. 1997, MN- RAS, 290, 623
. J J González, MNRAS. 0001Univ. California c 2002 RASPh.D. thesisGonzález, J. J. 1993, Ph.D. thesis, Univ. California c 2002 RAS, MNRAS 000, 1-??
. R G Gratton, E Carretta, F Matteucci, C Sneden, A& A. 358671Gratton, R. G., Carretta, E., Matteucci, F. & Sneden, C. 2000, A& A, 358, 671
. L Greggio, A Renzini, A&A. 118217Greggio, L. & Renzini, A. 1983, A&A, 118, 217
. A Heger, S E Woosley, ApJ. 567532Heger, A. & Woosley, S. E. 2002, ApJ, 567, 532
. L Hernquist, ApJ. 356359Hernquist, L. 1990, ApJ, 356, 359
. I Iben, Jr, A V Tutukov, ApJS. 54335Iben, I., Jr. & Tutukov, A. V. 1984, ApJS, 54, 335
. Y Ishimaru, N Arimoto, PASJ. 491Ishimaru, Y., & Arimoto, N. 1997, PASJ, 49, 1
. I Jørgensen, M Franx, P Kjaegaard, MNRAS. 2731097Jørgensen, I., Franx, M. & Kjaegaard, P. 1995, MNRAS, 273, 1097
. G Kauffmann, S D M White, B Guiderdoni, MNRAS. 264201Kauffmann, G., White, S. D. M. & Guiderdoni, B. 1993, MNRAS, 264, 201
. C Kobayashi, N Arimoto, ApJ. 527573Kobayashi, C. & Arimoto, N. 1999, ApJ, 527, 573
. D Koester, A&A. 378556Koester, D. et al. 2001, A&A, 378, 556
. H Kuntschner, MNRAS. 315184Kuntschner, H. 2000, MNRAS, 315, 184
. P Marigo, A Bressan, C Chiosi, A&A. 313545Marigo, P., Bressan, A. & Chiosi, C. 1996, A&A, 313, 545
. A Martinelli, F Matteucci, S Colafrancesco, MNRAS. 29842Martinelli, A., Matteucci, F. & Colafrancesco, S. 1998, MNRAS, 298, 42
. F Matteucci, L Greggio, A&A. 154279Matteucci, F. & Greggio, L. 1986, A&A, 154, 279
. F Matteucci, A& A. 28857Matteucci, F. 1994, A& A, 288, 57
. F Matteucci, S Recchi, ApJ. 558351Matteucci, F. & Recchi, S. 2001, ApJ, 558, 351
. F Menanteau, R G Abraham, R S Ellis, MNRAS. 3221Menanteau, F., Abraham, R. G. & Ellis, R. S. 2001, MNRAS, 322, 1
. J C Mihos, L Hernquist, ApJ. 427112Mihos, J. C. & Hernquist, L. 1994, ApJ, 427, 112
. J F Navarro, C S Frenk, S D M White, ApJ. 490493Navarro, J. F., Frenk, C. S. & White, S. D. M. 1997, ApJ, 490, 493
. K Nomoto, K Iwamoto, N Kishimoto, Science. 2761378Nomoto, K., Iwamoto, K. & Kishimoto, N. 1997 Science, 276, 1378
. E Pancino, L Pasquini, V Hill, F R Ferraro, M Bellazzini, ApJ. 568101Pancino, E., Pasquini, L., Hill, V., Ferraro, F. R. & Bellazzini, M. 2002, ApJ, 568, L101
. R F Peletier, F ; R, R L Davies, G D Illingworth, L E Davis, M Cawson, AJ. 1001091Univ. Groningen PeletierPh.D. thesisPeletier, R. F. 1989, Ph.D. thesis, Univ. Groningen Peletier, R. F., Davies, R. L., Illingworth, G. D., Davis, L. E. & Cawson, M. 1990, AJ, 100, 1091
. R F Peletier, A Vazdekis, S Arribas, C Del Burgo, B García-Lorenzo, C Gutiérrez, E Mediavilla, F Prada, MNRAS. 310863Peletier, R. F., Vazdekis, A., Arribas, S., del Burgo, C., García- Lorenzo, B., Gutiérrez, C., Mediavilla, E. & Prada, F. 1999, MNRAS, 310, 863
. S Perlmutter, ApJ. 517565Perlmutter, S. et al. 1999, ApJ, 517, 565
. M M Phillips, ApJ. 41375Phillips, M. M. 1993, ApJ, 413, L75
. A G Riess, AJ. 1161009Riess, A. G. et al. 1998, AJ, 116, 1009
. E E Salpeter, ApJ. 121161Salpeter, E. E. 1955, ApJ, 121, 161
. J Scalo, Fundam. Cosmic Phys. 111Scalo, J. 1986, Fundam. Cosmic Phys., 11, 1
. M Schmidt, ApJ. 137758Schmidt, M. 1963, ApJ, 137, 758
. J Sommer-Larsen, M Gotz, L Portinari, astro- ph/0204366Sommer-Larsen, J., Gotz, M. & Portinari, L. 2002, astro- ph/0204366
. S C Trager, S M Faber, G Worthey, J J González, AJ. 1191645Trager, S. C., Faber, S. M., Worthey, G. & González, J. J. 2000a, AJ, 119, 1645
. S C Trager, S M Faber, G Worthey, J J González, AJ. 120165Trager, S. C., Faber, S. M., Worthey, G. & González, J. J. 2000b, AJ, 120, 165
. M J Tripicco, R A Bell, AJ. 1103035Tripicco, M. J. & Bell, R. A. 1995, AJ, 110, 3035
. F Thielemann, Nomoto, Yokoi, A&A. 15817Thielemann, F., Nomoto, & Yokoi 1986, A&A, 158, 17
. F Thielemann, Nomoto, Hashimoto, ApJ. 460408Thielemann, F., Nomoto, & Hashimoto 1996, ApJ, 460, 408
A V Tutukov, L R Yungelson, Close binary stars, IAU symp. M. J. Plavec, D. M. Popper and R. K. Ulrich, Reidel, Dordrecht15Tutukov, A. V. & Yungelson, L. R. 1980, in Close binary stars, IAU symp. no. 88, eds. M. J. Plavec, D. M. Popper and R. K. Ulrich, Reidel, Dordrecht, p.15
. J Whelan, I Iben, Jr, ApJ. 1861007Whelan, J. & Iben, I., Jr. 1973, ApJ, 186, 1007
. S D M White, MNRAS. 1911White, S. D. M. 1980, MNRAS, 191, 1
. S Woosley, T Weaver, ApJS. 101181Woosley, S. & Weaver, T. 1995, ApJS, 101, 181
. G Worthey, S M Faber, J J González, ApJ. 39869Worthey, G., Faber, S. M. & González, J. J. 1992, ApJ, 398, 69
. G Worthey, ApJS. 95107Worthey, G. 1994, ApJS, 95, 107
. R F G Wyse, ApJ. 49069Wyse, R. F. G. 1997, ApJ, 490, L69
| [
-0.20896868407726288,
-0.1537860631942749,
0.15061233937740326,
0.17128106951713562,
0.06363438069820404,
-0.019588422030210495,
-0.15840715169906616,
0.13501790165901184,
0.12547558546066284,
0.045606061816215515,
0.0015798434615135193,
-0.17833353579044342,
0.0435175821185112,
-0.1267137... |
POLÍTICA CULTURAL E "CRISE" NO GOVERNO TEMER
Amanda P Coutinho De Cerqueira
POLÍTICA CULTURAL E "CRISE" NO GOVERNO TEMER
Cultural Policy Neoliberalism Cultural entrepreneurship
RESUMO: O artigo insere-se no esforço de análise da "crise" na política cultural brasileira. Trata-se de mapear a tentativa da construção da institucionalidade da área cultural no Brasil, junto com seu aparato legal e discursivo que reflete um projeto de implementação de ações governamentais, informando o percurso e o lugar do Estado no campo da cultura. No recorte, o governo Temer e as atuais movimentações de uma pauta de viés neoliberal. O movimento de retração do Estado e avanço da lógica de mercado tem consequências no empreendedorismo cultural forçado e precário, além de remeter a uma larga e difícil agenda política.Palavras-Chave: Política Cultural. Neoliberalismo. Empreendedorismo cultural.ABSTRACT:The article is part of the effort to analyze the "crisis" in Brazilian cultural policy.It is a question of mapping the attempt to build the institutionality of the cultural area in Brazil, along with its legal and discursive apparatus that reflects a project of implementation of governmental actions, informing the course and place of the State in the field of culture. Do not cut, the Temer government and the current movements of a neoliberal bias. The movement of retraction of the State and advance of the logic of market has consequences in the forced and precarious cultural entrepreneurship, besides referring to a long and difficult political agenda.Considerações iniciais: A "crise" e o que está em jogoAo contrário da perspectiva do capitalismo organizado, o filósofo húngaro István Mészáros (2009) entende que a substância das crises (crise especulativa, crise bancária, crise financeira etc.) vem de fundamentos estruturais e sistêmicos. Para o autor, o capitalismo vive uma permanente crise estrutural, uma vez que, por não ter limites para a sua expansão, acaba por converter-se em uma processualidade profundamente destrutiva. As contradições * Doutora em Ciências Sociais na Universidade Estadual de Campinas (UNICAMP), na linha de pesquisa Cultura e Política.
fundamentais, no entanto, são tratadas como disfunções passageiras. E é assim que, de tempos em tempos, para a sua auto-reprodução, o capitalismo é chamado a reestruturar-se para redefinir e assegurar seus padrões de acumulação e rentabilidade.
No contexto dos diferentes momentos históricos de reestruturações do capitalismo, os antagonismos são postos à mesa e a agenda da cultura é constantemente ainda mais reduzida.
Politicamente é, em geral, o nível da relação entre governo e sociedade o elemento determinante da crise do primeiro, o que resulta da sua falta de representatividade e de sua legitimidade, uma vez que é rejeitado por fortes setores sociais. Um momento de crise política, portanto, é aquele de acirramento de lutas de representatividade em torno de poderes econômicos, sociais e também culturais em que os agentes reivindicam para si o poder de nomeação, que é próprio do Estado (BARBALHO, 2018).
O que está em jogo na retórica da "crise" política, então, é a disputa por uma concepção de Estado diante de uma crise estrutural do capitalismo. Nesse contexto é que se situa o projeto do governo Temer, o qual defende o Estado mínimo, não apenas no setor produtivo, mas inclusive na promoção de direitos coletivos e nas responsabilidades sociais.
Elaborado inicialmente no manifesto "Uma ponte para o futuro", de outubro de 2015, e depois mais sistematizado no documento "A travessia social", já em 2016, ambos produzidos e publicizados pela fundação Ulysses Guimarães do PMDB, "vale salientar, a cultura e as políticas culturais não são contempladas em momento algumo que sinaliza o desconhecimento ou o não reconhecimento de seu papel estratégico para o país" (BARBALHO, 2018, p. 2). No âmbito cultural, faz-se necessário levar em consideração a estrutura em que se desenvolveram tais políticas, suas especificidades históricas e suas conjunturas atuais.
O percurso e o lugar do Estado no campo da cultura
Conforme elucida Alexandre Barbalho (2018, p. 2), "na cultura, a crise vem de antes". Segundo Antonio Rubim (2008, p. 32), a história das políticas culturais no Brasil está marcada por tristes tradições que podem ser condensadas nas seguintes expressões: autoritarismo, caráter tardio, descontinuidades e fragilidade institucional. Essa herança é analisa pela historiadora social Lia Calabre (2009). A autora parte dos anos 1930, período no qual o país passou por significativas mudanças políticas, econômicas, administrativas, com processo de urbanização industrial crescente, para entender as ações que tomaram formas de políticas culturais. Experiências federais e municipais desenharam as primeiras tentativas institucionais brasileiras no campo da cultura.
Na instância federal, no primeiro governo de Getúlio Vargas (1930-1945, a administração pública perseguia a construção de um novo modelo de gestão que buscava romper com a tradição da república oligárquica. No
Neoliberalismo e o empreendedorismo cultural precário
Enquanto as tentativas de fortalecimento institucional do Estado encontram interrupções, limites e dificuldades de realização prática, a supremacia da escolha política neoliberal nas políticas públicas culturais prevalece e pode ser evidenciada nas cifras disponibilizadas. A maior parte dos recursos aplicados em cultura por meio das leis de incentivo são recursos públicos da renúncia fiscal via Mecenato. Já os gastos governamentais diretos com a cultura nas esferas federal, estadual e municipal totalizam cerca de 0,3% do total das despesas consolidadas da administração pública (CALABRE, 2009, p. 21). Para Marilena Chauí (2006) a privatização da gestão da cultura fica mais clara, por exemplo, quando se destina 300 milhões ao Fundo Nacional de Cultura e um bilhão e 300 milhões para a renúncia fiscalque também é dinheiro público, mas destinado a atender interesses privados (CHAUÍ, 2006, p. 47). É como se o governo sacrificasse uma massa de dinheiro público capaz de ser empregada diretamente por suas instituições culturais para agir indiretamente, deixando às empresas a decisão do que financiar. Em outras palavras, seria como sacrificar receita pública convertendoa em reforço do orçamento publicitário das empresas.
Para explicar o mecanismo de funcionamento do Mecenato, Juliana Coli (2006, p. 266) elucida que as leis de incentivos fiscais acabam por privilegiar duplamente o capital privado: primeiro, pela própria concessão dos benefícios que a empresa obtém com a isenção dos impostos e, segundo, porque converte em retorno produtivo, como valor agregado, o que antigamente poderia ser considerado um investimento improdutivo, pelas novas estratégias de marca das empresas com o marketing cultural. Na lógica do Mecenato o envolvimento do setor corporativo nas questões culturais é otimizado tanto para estratégias de rentabilidade financeira, quanto para marketing de responsabilidade sociocultural. Entre as atuais estratégias das empresas, o marketing cultural representa uma forma de interação com os consumidores, cuja razão de ser econômica não se limita à venda do produto, mas à própria produção de subjetividade, enquanto forma de adesão ideológica. Nessa direção, o patrocínio corporativo tem também como objetivo o ganho simbólico, ou de imagem, que a associação a um evento de prestígio pode oferecer às corporações e suas marcas.
Nesse contexto, a pesquisadora Clarissa Diniz (2011, p. 33) explica que o "capitalismo ético" aponta para a ideia do "cada um deve fazer o seu papel" e parte do princípio de que se estaria vivendo uma crise conjuntural (e não estrutural) econômica e social. A partir da premissa que considera o Estado incapaz para lidar com as dimensões dessa crise, se aposta na iniciativa privada. O que ocorre com a questão sociocultural, enquanto território mais intensamente habitado pelo empresariado, é a superação da dimensão "problema social" para tornar-se, claramente, um campo de disputa de estratégia comercial entre as empresas. Nesse sentido, a pesquisadora (DINIZ, 2011, p. 33) explica que a Lei Rouanet permite que a empresa patrocinadora abata mais do imposto devido do que seu próprio investimento em cultura. O exemplo que segue destrincha esse mecanismo. (DINIZ, 2011, p. 38) No mesmo sentido de observação, a pesquisadora taiwanesa Chin-Tao Wu (2006) analisa o processo que fez da arte um grande negócio para as corporações. A autora (WU, 2006, p Mas em um contexto de escolha política neoliberal em que o Estado se isenta progressivamente do seu papel de garantidor de direitos, o mercado é oferecido como uma instância substituta para a cidadania. Para os artistas, tornar-se empreendedor cultural passar a significar a integração ao campo cultural. Essa integração é realizada de forma bastante desigual, principalmente se for levada em conta as especificidades dos interesses empresariais.
A ausência do debate sobre as causas de desigualdades nas políticas culturais, contudo, remete a uma larga e difícil agenda cultural e política. Acentua-se o crescimento do mercado de projetos e gestores especializados em editais, muitas vezes tecnocratos e complexos. Ao mesmo tempo em que o mercado de editais corrobora para o privilégio de nomes que já possuem condições econômicas, projeção artística e inserção no meio burocrático cultural, por outro lado, há uma série de restrições que chegam a inviabilizar pequenos projetos, que ficam incomodamente dependentes do capital de relações sociais de cada agente criador ou de cada instituição específica.
Em meio à corrida de editais e patrocínios, o artista é chamado a comportar-se como empresário da sua própria carreira, um portfólio worker, a custo de uma forte gestão de racionalidade dos seus capitais pessoais (tempo, esforço, competências, reputação). Tais fatores configuram o artista quase-firma. Operando individualmente, em freelancer e/ou em rede, associações e parcerias, os artistas entram, então, na corrida do empreendedorismo precário.
Emergem as políticas alternativas de financiamento, como o crowdfunding -a cooperação na arrecadação de recursos, tanto financeiros quanto estruturais, que ocorre geralmente por meio da internet; além do estabelecimento de parcerias diversas com empresas e mesmo fornecedores de produtos para publicidade, como tênis, instrumentos, roupas etc. (CERQUEIRA, 2017).
Esse laboratório de flexibilidade (MENGER, 2005) em uma economia política das incertezas faz com que a esfera das ocupações artísticas desenvolva as mais variadas formas flexíveis de trabalho e hibridações de atividades. Esses destaques apontam para a ironia de que não só as atividades de criação artística deixaram de ser a face oposta do trabalho, como elas são, cada vez mais, assumidas como a expressão mais avançada dos novos modos de produção.
As artes que, desde há dois séculos, têm cultivado uma oposição radical em relação ao mercado, aparece exatamente como precursora na experimentação da flexibilidade, ou até da hiperflexibilidade em um mercado de trabalho ultraindividualizado.
Considerações finais: A agenda da cultura
A proposição neoliberal que coloca a cultura como um bom negócio trouxe significativa redução de políticas públicas voltadas ao setor e apresentou como modelo para o desenvolvimento da cultura a participação de empresas por meio da lógica de patrocínio com contrapartidas fiscais. Nesse contexto, a discussão sobre políticas públicas e direito à cultura e diversidade resta bastante prejudicada. Para que as políticas públicas culturais possam se contrapor à hegemonia neoliberal e seus efeitos de aprofundamento das desigualdades, de consolidação do mercado e do interesse privado, torna-se essencial uma reflexão acerca da partilha efetiva dos recursos e dos poderes, de forma a propiciar a participação política dos grupos tradicionalmente considerados objeto do desenvolvimento que devem tornar-se sujeito desse processo, com identidade própria, mas também coletiva.
A promulgação da Lei Rouanet configura-se, desde então, como a principal regulação de financiamento à cultura no país. Por meio de seus mecanismos, subsidia-se a cultura diretamente via Fundo Nacional de Cultura (FNC), indiretamente por meio do Mecenato e ainda via Fundos de Investimento Cultura e Artístico (FICART). Entre as modalidades de financiamento, o Mecenato destaca-se como principal meio incentivador. Neste caso, o subsídio se concretiza por benefícios fiscais ao imposto de renda devido, tanto no caso de pessoa física quanto jurídica. Segundo a Lei Rouanet, pessoas físicas ou jurídicas podem patrocinar um projeto cultural (com permissão de promoção e publicidade do incentivador), caso em que se permite a dedução de até 100% do valor do patrocínio, sempre respeitados os limites do imposto devido ao incentivador.Durante o governo de Fernando Henrique Cardoso é possível observar a evidência do paradigma gerencial empresarial aplicado à administração pública. Nesse período, o incentivo indireto por meio do Mecenato presente na Lei Rouanet se torna o grande instrumento de política pública cultural. Essa situação proporcionou o surgimento de uma série de iniciativas privadas na área da cultura, ao mesmo tempo em que retirou o Estado do cenário decisório e da condução política do processo. Esse movimento de retração do Estado e avanço da lógica de mercado expressa mais que uma configuração econômica, mas também uma escolha política pelo conceito liberal na gestão cultural. No mesmo período do governo Fernando Henrique Cardoso em que se observa o destaque para a gestão liberal surgem novas configurações no campo social e político brasileiro. As lutas sociais e o processo de organização popular fizeram com que em 1989 a nordestina Luiza Erundina fosse eleita prefeita do município de São Paulo, pelo Partido dos Trabalhadores (PT), que, por sua vez, convidou a filósofa e historiadora Marilena Chauí para assumir a pasta da Secretaria de Cultura. Chauí pautou sua gestão pela recusa do modelo liberal e instituiu o conceito de cidadania cultural. Para a pesquisadora (CHAUÍ, 2006, p. 23), a cultura precisa ser entendida pelas políticas públicas como direito dos cidadãos, sem confundi-lo com as figuras do consumidor e do contribuinte, enquanto o Estado deve assumir a postura de assegurador público de direitos, prestador sociopolítico de serviços e estimulador-patrocinador das iniciativas da sociedade. No contexto internacional, a cultura passa a fazer parte de forma mais enfática do rol de reivindicações dos organismos transnacionais. A expansão dos mercados culturais coloca em pauta discussões em torno do tema. Apropriando-se desse debate e reivindicando a cultura como uma das áreas de sua competência específica, a UNESCO passa a encabeçar discussões e realizar inúmeras convenções, com o objetivo de regulamentar e formular recomendações para o reconhecimento e valorização da diversidade cultural. Documentos jurídicos internacionais sobre Direitos humanos fazem menção aos Direitos culturais, enquanto outros foram e estão sendo elaborados no sentido de vincular cultura ao desenvolvimento social e econômico, desde a Declaração Universal dos Direitos Humanos (1948), passando pelo Pacto Internacional dos Direitos Econômicos, Sociais e Culturais (1966), até a Declaração Universal Sobre a Diversidade Cultural (2002), apenas para citar alguns exemplos. A relativa retomada do papel ativo do Estado brasileiro nas políticas públicas culturais se dá nos governos do presidente Luiz Inácio Lula da Silva. Entre os anos de 2003 a 2010 há um esforço no sentido de estabelecer um diálogo e compartilhar com a sociedade brasileira a revisão, formulação, estruturação e execução das políticas setoriais. Nesse período, foram realizadas importantes iniciativas de sustentação e operacionalização, como o Sistema Nacional de Cultura (SNC), o Conselho Nacional de Política Cultural (CNPC) e o Programa de Desenvolvimento Econômico da Cultura (PRODEC). Além disso, o slogan "Cultura para todos" procurou materializar a descentralização e diversidade cultural com o Programa Cultura Viva, que institui os Pontos de Cultura, e o Mais Cultura. Na gestão de Gilberto Gil estimulou-se um processo de discussão e reorganização do orçamento com objetivo de melhorar distribuição dos recursos destinados à cultura. Pela primeira vez foi proposta uma revisão pública para corrigir as limitações da Lei Rouanet. Estavam estabelecidas as bases do chamado neodesenvolvimentismo com participação estatal. Para aprofundar a tentativa de combate ao ciclo de descomprometimento do Estado com a cultura, o Governo Dilma Rousseff apresentou o planejamento a longo prazo do Plano Nacional de Cultura (PNC), formulado com a participação de consultas nacionais e regionais por meio de fóruns e conferências realizados pelo país. Cita-se também o Sistema Nacional de Informações e Indicadores Culturais (SNIIC) e o Plano de Economia Criativa, assim como a aprovação e regulamentação do Vale-Cultura para trabalhadores. Tendo em vista esse contexto, Lia Calabre (2006, p. 23) afirma que o MinC, ao longo dos últimos dez anos do governo petista buscou construir as bases para a consolidação das políticas públicas no Brasil. Houve um esforço continuado de fortalecimento das instituições culturais e de estabelecimento das diretrizes, amparadas na valorização de uma democracia cultural e na utilização desta como instrumento de inclusão social, transformando as políticas culturais, minimamente, em políticas de Estado.É importante lembrar, contudo, que o primeiro governo Dilma (2011-2014), ainda que representando uma continuidade do projeto político capitaneado pelo PT, trouxe mudanças significativas no que se refere às políticas culturais. Conforme destaca Alexandre Barbalho (2018), não cedendo à pressão de vários setores, inclusive de seu próprio partido, pela permanência de Juca Ferreira no Ministério, a presidenta nomeou, em janeiro de 2011, a artista Ana de Hollanda como ministra da Cultura. Reconfigurando a composição das forças políticas no interior do MinC, propondo novas pautas, dando continuidade a programas anteriores e enfraquecendo ou mesmo extinguindo outros, Hollanda provocou um forte movimento de oposição, inclusive interna, à sua gestão, o que terminou por afastá-la do cargo em setembro de 2012. 2. Temer e o desmonte da pasta Com a perda do cargo de presidente da república, após sofrer processo de impedimento em 2016, Dilma Rousseff é substituída pelo seu vice, Michel Temer (PSDB). Como uma de suas primeiras medidas, Temer extinguiu o MinC, que se transformou em Secretaria subordinada ao MEC, comandado por Mendonça Filho (DEM). À sombra do argumento do corte de gastos, a decisão de extinção do MinC gerou uma enorme insatisfação da classe artística. Vários prédios ligados ao Ministério e entidades vinculadas foram ocupados em todo o Brasil. Emergiram protestos, abaixo-assinado e manifestações nacionais e internacionais. Temer decidiu, então, um mês mais tarde, recriar o MinC, que, de acordo com Mendonça, tratou-se de um "gesto do presidente Temer no sentido de serenar os ânimos", nomeando Marcelo Calero como Ministro. Mas a volta da instituição não travou o desmonte generalizado da cultura. A estratégia do governo tem sido a implosão. Sob o comando de Calero, o Ministério da Cultura efetivou a exoneração de 81 comissionados que não tinham vínculo com o serviço público federal. Segundo o Ministério, as exonerações fazem parte da reestruturação da pasta, do plano de valorização dos servidores de carreira e do "desaparelhamento" do MinC, o que levou movimentos organizados a alegar perseguição política de Temer, sobretudo se for observado os nomes que foram exonerados (ligados e atuantes no movimento de ocupação dos prédios do MinC). Há muito tempo a pasta sofre com a ausência e precarização do seu quadro de pessoal. Em 2016, os dados da Diretoria de Gestão Estratégica do MinC, retratou que a força de trabalho do Ministério é composta por apenas 18,7% de pessoal permanente. Os outros se distribuem entre sem vínculo, terceirizados, consultores, requisitados e estagiários (MINC, 2016). Com as exonerações atuais, o Ministério informou que abriria concursos para o preenchimento das vagas, o que não aconteceu. O então Ministro da Cultura, 33 anos, diplomata e advogado, era secretário municipal de cultura do Rio de Janeiro do governo de Eduardo Paes (PMDB), quando foi convidado por Temer para o Ministério. Calero chegou a se candidatar a deputado federal em 2010 no Rio de Janeiro pelo PSDB, endossando a campanha de José Serra à Presidência, tendo conseguido 2.252 votos. Após cerca de seis meses, Marcelo Calero pediu demissão do MinC, acusando o então ministro da Secretaria de Governo, Geddel Vieira Lima, de tê-lo pressionado a liberar a construção de um arranha-céu em Salvador em uma área tombada pelo IPHAN, aonde Geddel havia comprado um apartamento. Geddel caiu seis dias depois. Para o lugar de Calero, foi anunciado o presidente nacional do PPS, o deputado federal Roberto Freire. O pernambucano Freire nunca assumiu cargos (nem mesmo de segundo escalão) nas gestões que seu próprio partido apoiou, como as dos governos paulistas. Cerca de seis meses depois de assumir o Ministério, Roberto Freire deixou o governo Michel Temer em meio às acusações de corrupção e obstrução da justiça envolvendo o atual presidente. De forma interina, o cineasta João Batista de Andrade (PPS) ocupou o cargo por dois meses. Com o anúncio do corte de 43% do Orçamento do MinC, Andrade pediu demissão do cargo. Na sua avaliação, o ambiente não era propício a uma boa política cultural e, com o corte orçamentário, o ministério teria ficado inviável. Após dois meses sem titular na pasta, é a hora e a vez jornalista, escritor, gestor público e cineasta Sérgio Sá Leitão, que foi chefe de gabinete do então ministro Gilberto Gil (2003-2006) e secretário de Políticas Culturais do MinC. Com o quarto nome, em pouco mais de um ano de governo Temer, o MinC segue, então, o seu curso de sucessivas instabilidades governamentais. Não é de estranhar que, com essa trajetória ligada ao MinC e à gestão municipal de cultura de uma cidade administrada pelo PMDB, Leitão apareça como um importante nome hoje no Ministério. Conforme analisa Barbalho (2018, p. 13): Na realidade, havia uma pressão para que a nomeação fosse política, mas diante do receio de mais reações contrárias do campo cultural, optou-se por uma indicação técnica e com trânsito no meio político. Ou seja, tratava-se de um agente que reunia a capacidade de defesa do governo a partir do lugar institucional da cultura e a de propor uma política cultural adequada à política governamental. Em adequação ao posicionamento esperado, o ministro, logo após assumir o cargo, se propôs a criar consensos entre os agentes do campo ao se colocar como ministro de toda a cultura brasileira e a favor do bom senso e da contemporaneidade. Ao mesmo tempo, em seu discurso de posse, defendeu as reformas do governo. O plano de ações que o ministro apresentou ao presidente Temer se estrutura em cinco pilares. O primeiro é o "choque de gestão em busca da eficiência"; o segundo é um conjunto de reformas, que inclui a Lei Rouanet, mas também os modelos de gestão dos equipamentos culturais sob responsabilidade do governo federal, uma vez que o padrão de gerenciamento integralmente estatal não seria mais viável, o que exigiria "ceder a administração desses espaços culturais a organizações sociais e à iniciativa privada" (BRASIL, 2018); o terceiro é a entrega de programas que estão sendo executados pelo Ministério e por suas vinculadas; o quarto pilar é a construção do plano de diretrizes e metas do MinC para a área cultural, que deverá orientar, inclusive, as futuras gestões do Ministério; por fim, o quinto pilar é a economia da cultura, "uma bela contribuição nesse momento em que o Brasil começa a sair da crise." (BRASIL, 2018). Para tanto, o atual ministro aposta veementemente na Lei Rouanet, "com ênfase em sua dimensão econômica para promover o desenvolvimento do país e o bem-estar da coletividade" Rouanet. Esta é a quinta edição da IN desde a promulgação da Lei, em 1991. As INs anteriores foram publicadas em 1991, 2010, 2012 e em março de 2017. A segunda e mais significativa IN no governo Temer possui um texto enxuto e objetivoo número de artigos da nova IN foi reduzido de 136 para 73 artigos, e tem a narrativa da desburocratização e da flexibilização a fim de atrair empresas patrocinadoras. As atualizações, entre outras medidas, sobe o teto do valor incentivado pelos proponentes, aumentando a atratividade para os patrocínios, assim como sobe também a permissão para o valor dos ingressos cobrados pelos eventos patrocinados, para R$ 250,00 (cinco vezes o valor do vale-cultura). Em Junho deste ano, o MinC também passou por uma a reestruturação organizacional com o objetivo de ampliar a eficiência e eficácia da instituição, demitindo alguns secretários e realizando a fusão de alguns secretarias, como a Secretaria da Cidadania e da Diversidade Cultural que uniu-se a Secretaria de Articulação e Desenvolvimento Institucional.
contexto de esboço de uma racionalidade legal-administrativa de organização institucional do Estado foi criado o Ministério da Educação e Saúde (MES), conduzida pelo Ministro Gustavo Capanema, cuja legislação do Conselho Nacional da Educação fazia referência à cultura pela primeira vez no país. O conceito legislativo de cultura na segunda metade da década de 1930 era abrangente e de caráter nacionalista. As atribuições do Conselho abarcaram as áreas clássicas das artes, os meios de comunicação, a produção intelectual, a educação cívica e a física, inclusive as atividades de lazer, além da proposição de pesquisas setoriais. O presidente Vargas contava com a simpatia da classe teatral desde os tempos em que foi deputado, antes da Revolução de 1930, quando apresentou um projeto que reconhecia a existência da profissão do artista teatral. Durante a sua gestão diversas iniciativas foram propostas no âmbito cultural, como por exemplo, a criação do Conselho Nacional de Cultura (CNC). Foram criados também o Serviço de Patrimônio Histórico e Artístico Nacional (SPHAN), o Museu Nacional de Belas Artes, o Museu Histórico Nacional, o Instituto Nacional do Livro, o Instituto Nacional do Cinema Educativo, o Departamento de Imprensa e Propaganda (DIP), entre outros serviços e instituições. O governo de Getúlio Vargas também foi marcado por ambiguidades. Segundo Antonio Rubim (2008, p. 34), essa foi a primeira vez que o Estado nacional realizava um conjunto de intervenções na área da cultura, articulando, ao mesmo tempo, uma atuação de caráter afirmativo estruturada por meio de formulações legislativas, institucionais e organizacionais; e práticas tendentes a repressão e censura. Nesse mesmo período, ocorreu a primeira experiência de gestão de política pública municipal. Trata-se da criação do Departamento de Cultura e Recreação do Estado de São Paulo, em 1935, capitaneada e chefiada por Mário de Andrade, e ligada a alguns dos ideais presentes no Movimento Modernista Brasileiro. O ciclo que sucedeu o presidente Vargas não apresentou um programa cultural consistente. As décadas de 1940 e 1960 foram marcadas por uma fraca presença do Estado no campo da cultura. A maior parte das ações se restringia a regulamentar e dar continuidade às instituições que foram criadas ao longo do governo Vargas. Surgiram experiências não estatais relevantes como, por exemplo, os Centros Populares de Culturas (CPCs), da União Nacional dos Estudantes (UNE). O crescimento urbano-industrial gerava novas expectativas sobre a possibilidade de desenvolvimento do mercado de consumo para as produções artísticoculturais. Crescia a indústria cultural no Brasil, marcada por um processo significativo de investimento privado. Ainda em 1946, foi criado, junto ao Ministério das Relações Exteriores (MRE), o Instituto Brasileiro de Educação, Ciência e Cultura (IBECC). Em 1953, a área da saúde finalmente ganha um ministério próprio e surge o MEC. Lia Calabre (2009, p. 43) analisa que entre as décadas de 1960 e 1970, as questões relacionadas à cultura ganharam maior importância dentro da área de planejamento público e passaram a ser incluídas nas noções de desenvolvimento. Na década de 1960, antes do golpe de 1964, o Governo Federal implementou algumas ações visando estruturar uma política para o setor. Em 1961 foi criado o Conselho Nacional de Cultura (CNC), diretamente subordinado à Presidência da República, ocupado por Jânio Quadros. A visão de cultura presente na legislação do Conselho estava limitada à área artístico-cultural, não contemplando, por exemplo, questões de educação, lazer e esporte, presente na visão varguista. Em 1971, o país contava com conselhos de cultura instalados e em pleno funcionamento em 22 estados. Durante este período destaca-se, ainda, a criação da Empresa Brasileira de Filmes S.A. (Embrafilme), em 1969. Nos anos de 1970 a estrutura administrativa do MEC é reformulada e o Conselho da Cultura passa a cumprir uma instância consultiva e normativa. Durante a gestão de Jarbas Passarinho (1969-1973) é implementado o Plano de Ação Cultural (PAC), importante projeto de financiamento de eventos, além do Departamento de Assuntos Culturais (DAC) e da Secretaria de Cultura no âmbito do MEC. Observa-se um processo de fortalecimento da área da cultura dentro do Ministério da Educação. Nesse período foram criados também o primeiro Plano Nacional de Cultura (PNC), em 1975, o Instituto de Patrimônio Histórico e Artístico Nacional (IPHAN) e a Fundação Nacional das Artes (FUNARTE). O Brasil começa a se abrir para novas dinâmicas internacionais por meio de encontros promovidos pela Organização das Nações Unidas para a Educação, a Ciência e a Cultura (UNESCO). Pela primeira vez no país é aprovada a regulamentação das profissões de "Artistas e Técnicos de Espetáculos" (Lei nº No fim dos anos 1970 é colocada a questão das distorções na criação, distribuição, acesso e consumo de bens culturais. Nesse período foi criada a Política Nacional de Cultura. Por meio do Decreto nº 91.144/1985 o governo de José Sarney cria o Ministério da Cultura (MinC), assumido no ano seguinte por Celso Furtado. Nessa época também foi aprovada a Lei nº 7.505/1986, conhecida com Lei Sarney, que concedia benefícios fiscais na área do imposto de renda para operações de caráter cultural ou artístico. Segundo Lia Calabre (2009, p. 33) embora tenha havido um esforço do Ministro Celso Furtado, reconhecido por buscar a estruturação institucional do MinC, o período de gestão do presidente Sarney foi de grande instabilidade política dentro do Ministério. O resultado de tal conjuntura foi a descontinuidade de projetos e pesquisas no setor. O início da década de 1990 sofreu um grande desmonte na área cultural do que tinha sido construído até então. O presidente Fernando Collor de Mello promulgou as Leis nº 8.028 e nº 8.029. A primeira transformava o Ministério da Cultura em Secretaria e a segunda extinguia uma série de entidades da administração pública, na qual a área da cultura foi duramente atingida. Foram dissolvidas, por exemplo: a FUNARTE, a Fundação Nacional de Artes Cênicas (FUNDACEN), a Fundação do Cinema Brasileiro (FCB), a Fundação Nacional Pró-Memória e a Embrafilme. Em substituição a Lei Sarney foi promulgada a Lei Federal nº 8.313/1991, vigente até o presente momento. A Lei Rouanet, como ficou conhecida, instituiu o Programa Nacional de Apoio à Cultura (PRONAC), cuja finalidade é a captação de recursos financeiros para os diversos setores culturais. Finalmente, em 1992, a situação que transformou o MinC em Secretaria da Cultura foi revertida.6.533/1978).
A Secretaria da Economia da Cultura passa a se chamar Economia Criativa, sob o comando de Douglas Capela, ex-executivo do Banco do Brasil, cujo conceito de cultura volta a ser mais amplo. Sá Leitão também oficializou a criação da Secretaria de Direitos Autorais e Propriedade Intelectual. Finalmente, um dos maiores entraves históricos do MinC na efetividade de suas demandas é o seu baixo orçamento. A propósito da viabilização da atuação direta do Estado na cultura, desde 2003 tramita no Congresso Nacional a Proposta de Emenda Constitucional 150. A PEC 150 prevê o repasse anual de 2% do orçamento federal, 1,5% do orçamento dos estados e do Distrito Federal e 1% do orçamento dos municípios para a cultura. Mas, no atual contexto político, a PEC aprovada foi a 241, que congela o orçamento do governo federal por vinte anos, impactando diretamente na área cultural, com significativa redução de investimentos. O que nem todo mundo se deu conta ainda é que na área cultural, a PEC é ainda mais devastadora. Isso porque, diferentemente da saúde e educação, que possuem pisos orçamentários obrigatórios previstos na Constituição, a cultura não tem essa garantia e, com isso, pode perder até 90% dos seus recursos em apenas cinco anos. A projeção foi apresentada pelo ex-secretárioexecutivo do MinC, João Brant (2016, p. 1). Em nota técnica, Brant (2016), que foi secretário-executivo do ministério na gestão Dilma Rousseff até abril de 2016, explica que com a queda de quase 90% do orçamento voltado para as ações culturais, na prática, todas as ações do MinC serão paralisadas. Isso inclui editais de pontos de cultura, ações voltadas à cultura negra, obras de patrimônio cultural e exposições de museus, financiamentos não-retornáveis do Fundo Setorial do Audiovisual, além de ações de digitalização da Biblioteca Nacional, bolsas da Fundação Casa de Rui Barbosa e todas as ações financiadas pelo FNC. Com isso, a tendência é o fechamento de unidades inteiras vinculadas ao ministério ou até mesmo a transferência da gestão para a iniciativa privada (BRANT, 2016, p. 1).
Com base também nas suas ações de 'contribuição social e cultural', a marca do Itaú S.A consolidou-se em 2011 como a mais valiosa do Brasil, num total de R$ 24,3 bilhões, enquanto, no ano de 2010 investiu de recursos próprios R$ 59.266.000,00 (59 milhões) em cultura, o equivalente a 0,11% de sua receita líquida naquele ano. Não é diretamente, senão através, de tributação, como por meio da Lei Rouanet, que o Itaú S.A investe significativamente na 'questão social' havendo, em 2010, investido R$ 10.299.997.000,00 (10 bilhões) para todas as áreas das contribuições sociais, o equivalente a 19,10% de sua receita líquida. Considerando os 0,11% de investimento direto em cultura da corporação naquele ano, pergunto-me o quanto, por sua vez, não deve ter colaborado a cultura (e, portanto, a arte) para construir, através dos 19,10% de investimento via tributação, para o atual valor bilionário da marca, 18% superior ao de 2010. Restringindo-me a ficar em um dos braços das atividades culturais e sociais do conglomerado, somente no Itaú Cultural foram investidos, através da Lei Rouanet, R$ 26,978 milhões (segundo informações cedidas pela instituição, outros R$ 17,836 milhões foram investidos diretamente pelo Itaú Unibanco), havendo sido realizadas, em 2010, 456 atividades, recebidos quase 300.000 visitantes, distribuídos 25.673 produtos culturais e assinados contratos com 111 TVs
. 23) explica a tendência de privatização da cultura, a partir da intervenção corporativa nas artes na década de 1980 na Grã-Bretanha e nos Estados Unidos, década em que, mais do que em qualquer outra, se assistiu a utilização do poder corporativo na participação ativa da arena cultural. A entrada das companhias na arena cultural só se tornou possível graças à substancial acumulação de capital econômico, além do forte aparato de governabilidade. Depois da chegada de Ronald Reagan e Margaret Thatcher ao poder, em 1981 e 1979, respectivamente, os dois conduziram seus mandatos sob a dupla bandeira da redução dos gastos públicos e da expansão do setor privado, o que se estendeu à vida cultural dos dois países. Os cortes orçamentários vieram juntos com incentivos fiscais e influência política suficientes para atrair dinheiro privado para área.As estratégias de ações do thatcherismo e do reaganismo estabeleceram os paradigmas de gestão neoliberal na cultura, por meio do duplo movimento que endosssa a iniciativa privada e retrai o investimento direto do poder público. Proliferam-se os centros culturais mantidos por entidades financeiras. Para quem trabalha no setor, não há, inicialmente, um mal nessa lógica. Segundo Ana Carla Reis (2007, p. 67), o envolvimento das empresas requer um comprometimento muitas vezes mais complexo do que a posição de ser contra, na medida em que existe, para a autora (REIS, 2007, p. 34), a possibilidade de diferentes formas de participação privada (filantropa, oportunista, comercial, desenvolvedora). O problema acontece, contudo, quando a sinergia Estado / Mercado caminha na arriscada e quase sempre iminente direção de descomprometimento do Estado. Enquanto o Estado prescinde de sua atuação direta para descentralizar e democratizar os projetos culturais, o Mecenato, pela lógica do mercado, centraliza os recursos nos principais centros do país, áreas de interesse do marketing cultural das empresas, cuja visibilidade e retorno comercial é mais provável. Além disso, a Lei Rouanet promove investimentos bastante criticados, como ocorre frequentemente no Rock in Rio. Nesse sentido, quando o Estado se retrai naquilo que é em favor de interesses públicos, avançam interesses de mercado, que são corporativistas e, portanto, de benefício restrito. Do ponto de vista jurídico, embora as regulamentações brasileiras apontem para a valorização do discurso da cultura (a atual Constituição Federal anuncia a importância da cultura, definindo o papel do Estado em sua gestão, de forma a garantir a todos o pleno exercício dos direitos culturais, além de apoiar e incentivar a valorização e a difusão das manifestações culturais), ao procurar estimular o setor cultural majoritariamente por meio de leis de incentivo fiscal ao patrocínio privado, transfere-se de forma principal para as empresas uma obrigação genuinamente estatal. Nesse contexto, Marilena Chauí (2006, p. 52) conclui que a política pública cultural no Brasil, naquilo que implica deliberação, escolhas e prioridades, é propriedade das empresas e suas gerências de marketing. Símbolo do Estado mínimo, a Lei Rouanet vinha sendo repensada pelo MinC. Em uma série de encontros denominado "Diálogos culturais", em 2008, o então Ministro Juca Ferreira apresentou à sociedade civil as justificativas para reformulação legislativa, apontando as distorções do modelo de financiamento atual, assim como propostas de mudanças. O relatório do Minc (2015) concluiu que o modelo atual exclui a viabilidade dos projetos sem retorno de marketing, não fortalecem a sustentabilidade do mercado cultural, inibe a percepção de que os recursos são públicos e não promove a democratização do acesso aos bens culturais. O Projeto de Lei nº 6.722/2010 (ProCultura) pretendia ser o novo marco regulatório que substituiria a Lei Rouanet. Discutido em várias conferências pelo país, o Procultura fortalecia o incentivo Estatal direto via Fundo Nacional de Cultura. O Projeto, que também prevê a regionalização dos recursos, foi aprovado na Câmara dos Deputados com alterações ao texto originalmente apresentado e aguarda votação no Senado Federal. Em entrevistas (GRUMAN, 2015, p. 2) Juca Ferreira, grande entusiasta do ProCultura, se defende do argumento de dirigismo cultural no setor, afirmando que não é contrário à renúncia fiscal, mas à sua predominância enquanto forma de incentivo. O ex-ministro entende que a lógica deve ser invertida e o Estado deve ser o principal incentivador das atividades artísticas no país.
Política cultural em tempo de crise: o Ministério da Cultura no governo Temer. Revista de Políticas Públicas. Alexandre Barbalho, 221BARBALHO, Alexandre. Política cultural em tempo de crise: o Ministério da Cultura no governo Temer. Revista de Políticas Públicas. V. 22, nº 1 (2018). Disponível em http://www.periodicoseletronicos.ufma.br/index.php/rppublica/article/view/9230 Acesso em 18 de Julho de 2018.
PEC 241 pode tirar até 90% do orçamento finalístico da cultura em 5 anos. João Brant, BRANT, João. PEC 241 pode tirar até 90% do orçamento finalístico da cultura em 5 anos.
. Brasil Debate, Brasil Debate, 2016. Disponível em https://goo.gl/VG0CDM Acesso em 7/11/2017 Acesso em 2 de Julho de 2018.
Ministro apresenta plano de ações do MinC ao presidente. Brasil, Ministério Da Cultura, BRASIL. Ministério da Cultura. Ministro apresenta plano de ações do MinC ao presidente
Disponível em encurtador.com.br/nEJR8 Acesso em 23 de Maio de. Temer, D F Brasília, Agosto De, Temer. Brasília, DF, Agosto de 2018. Disponível em encurtador.com.br/nEJR8 Acesso em 23 de Maio de 2018.
Políticas culturais no Brasil: dos anos 1930 ao século XXI. Lia Calabre, FGVRio de JaneiroCALABRE, Lia. Políticas culturais no Brasil: dos anos 1930 ao século XXI. Rio de Janeiro: FGV, 2009.
Paradoxos da atividade artística na narrativa de músicos denominados independentes. Amanda P Cerqueira, Coutinho De, 1recurso online (218 p.). Tese (doutoradoCERQUEIRA, Amanda P. Coutinho de. Paradoxos da atividade artística na narrativa de músicos denominados independentes. 2017. 1 recurso online (218 p.). Tese (doutorado) -
Instituto de Filosofia e Ciências Humanas. Campinas, SPUniversidade Estadual de CampinasUniversidade Estadual de Campinas, Instituto de Filosofia e Ciências Humanas, Campinas, SP.
. Disponível. Disponível em: http://www.repositorio.unicamp.br/handle/REPOSIP/325515. Acesso em: 19 jul. 2018.
Cidadania cultural: o direito à cultura. São Paulo: Editora Fundação Perseu Abramo. Marilena Chauí, CHAUÍ, Marilena. Cidadania cultural: o direito à cultura. São Paulo: Editora Fundação Perseu Abramo, 2006.
Vissi d´arte por amor a uma profissão: Um estudo de caso sobre a profissão do cantor de teatro lírico. Juliana Coli, AnnablumeSão PauloCOLI, Juliana. Vissi d´arte por amor a uma profissão: Um estudo de caso sobre a profissão do cantor de teatro lírico. São Paulo: Annablume, 2006.
Partilha da crise: ideologia e idealismos. Clarissa Diniz, Revista Tatuí. Nº. 12FUNDARPEDINIZ, Clarissa. Partilha da crise: ideologia e idealismos. Revista Tatuí. Nº 12, Novembro de 2001. Recife: FUNDARPE, 2011.
. Norbert Elias, Mozart, Janeiro De Um Gênio. Rio De, Jorge ZaharELIAS, Norbert. Mozart, sociologia de um gênio. Rio de Janeiro: Jorge Zahar, 1995.
Retrato do artista enquanto trabalhador: metamorfoses do capitalismo. Lisboa: Roma Editora. Pierre-Michel Menger, MENGER, Pierre-Michel. Retrato do artista enquanto trabalhador: metamorfoses do capitalismo. Lisboa: Roma Editora, 2005.
A crise estrutural do capital. István Mészáros, São Paulo; BoitempoMÉSZÁROS, István. A crise estrutural do capital. São Paulo: Boitempo, 2009.
Relatório de gestão -Brasília. Ministério Da Cultura, MINISTÉRIO DA CULTURA. Relatório de gestão -Brasília, 2016. Disponível em file:///C:/Users/Amanda/Desktop/idSisdoc_10838926v1-87%20-%20RelatorioGestao.pdf
Economia da cultura e desenvolvimento sustentável: O caleidoscópio da cultura. Ana Carla Reis, Fonseca, ManoleBarueriREIS, Ana Carla Fonseca. Economia da cultura e desenvolvimento sustentável: O caleidoscópio da cultura. Barueri: Manole, 2007.
Rubens (Orgs.) Políticas culturais na iberoamérica. Salvador: EDUFBA. BAYARDO. BAYARDO, Rubens (Orgs.) Políticas culturais na ibero- américa. Salvador: EDUFBA, 2008.
Privatização da cultura: A intervenção corporativa nas artes desde os anos 1980. Chin-Tao Wu, São Paulo; BoitempoWU, Chin-Tao. Privatização da cultura: A intervenção corporativa nas artes desde os anos 1980. São Paulo: Boitempo, 2006.
. Recebido Em, 09-10-2017RECEBIDO EM 09-10-2017
| [
0.07482827454805374,
-0.016888264566659927,
-0.12126775085926056,
-0.1385868340730667,
-0.0904935747385025,
0.026287754997611046,
-0.02997339889407158,
0.08561277389526367,
0.04113739728927612,
0.14068345725536346,
0.0527874119579792,
-0.1440945416688919,
-0.0735912173986435,
-0.0496930591... |
Towards a Factor Graph-Based Method using Angular Rates for Full Magnetometer Calibration and Gyroscope Bias Estimation
Sebastián Rodríguez-Martínez
Giancarlo Troni gtroni@mbari.org
Towards a Factor Graph-Based Method using Angular Rates for Full Magnetometer Calibration and Gyroscope Bias Estimation
B1E5F936048816CA0C1DFB0C26493C5A
MEMS Attitude Heading Reference Systems are widely employed to determine a system's attitude, but sensor measurement biases limit their accuracy.This paper introduces a novel factor graph-based method called MAgnetometer and GYroscope Calibration (MAGYC).MAGYC leverages threeaxis angular rate measurements from an angular rate gyroscope to enhance calibration for batch and online applications.Our approach imposes less restrictive conditions for instrument movements required for calibration, eliminates the need for knowledge of the local magnetic field or instrument attitude, and facilitates integration into factor graph algorithms within Smoothing and Mapping frameworks.We evaluate the proposed methods through numerical simulations and in-field experimental assessments using a sensor installed on an underwater vehicle.Ultimately, our proposed methods reduced the underwater vehicle's heading error standard deviation from 6.21 • to 0.57 • for a standard seafloor mapping survey.
I. INTRODUCTION
Micro-Electro-Mechanical Systems (MEMS) Attitude and Heading Reference Systems (AHRSs) are widely used to determine system attitude, primarily in vehicle navigation systems operating in space, ground, and marine scenarios.They play a crucial role in GPS-denied applications, such as autonomous underwater vehicle deployments or navigation in enclosed spaces like tunnels, where inertial navigation is the primary means to estimate system state.Despite their importance, these sensors are susceptible to calibration errors and may not always provide accurate navigation.While expensive high-grade sensors (> 100k USD) can partially mitigate this issue, addressing calibration errors remains a challenge for mid and low-range sensors designed for widespread use, typically costing thousands of dollars.
A standard MEMS AHRS comprises a three-axis magnetometer, a three-axis accelerometer, a three-axis gyroscope, and a temperature sensor.The magnetometer measures the local Earth's magnetic field, aiding in determining the system's heading.The accelerometer, when external accelerations are minimal, measures the system's inclination relative to local gravity, providing pitch and roll orientation information.Lastly, the gyroscope offers the vehicle's angular rate, aiding in refining the rotation estimation.
Accurate estimation hinges on effectively mitigating biases, scale factors, and non-orthogonality issues that can affect AHRS components.Gyroscopes and accelerometers face challenges from biases, while magnetometers are also Diagram illustrating an underwater vehicle's dead reckoning position using different magnetic field sources for the heading estimation with the corresponding trajectories represented with dashed lines.
susceptible to calibration errors induced by nearby ferrous materials or electric currents, which can skew the magnetic field, leading to inaccuracies in heading estimation.There are two primary types of magnetometer calibration errors: hardiron biases, caused by permanent magnetic fields from the vehicle and onboard instruments, resulting in constant output bias, and soft-iron biases, arising from magnetic materials near the sensor, which distort the magnetic field with scale factors and non-orthogonalities.
The accurate calibration of three-axis magnetometers is essential for reliable attitude estimation.Various methods have been proposed to estimate calibration parameters without the need for additional reference sensors.One widely adopted approach Alonso and Shuster introduced is the TWOSTEP method.It initially estimates the magnetometer's bias [1], followed by estimating the scale and non-orthogonality factors as well using an iterative least squares minimization [2].Several least squares methods have been reported as well [3]- [5].Another formulation for magnetometer calibration treats it as an ellipsoid fitting problem, which Vasconcelos et al. [6] addressed using a maximum likelihood estimate method.
Given the availability of inertial sensors with magnetometers as a package, some strategies combine accelerometer and magnetometer measurements to estimate the magnetometer sensor biases, leveraging accelerometers to measure the local gravity vector [7]- [9].However, these methods are susceptible to calibration errors caused by translational accelerations.Troni and Whitcomb [10] introduced a novel approach that uses angular velocity measurements to estimate the magnetometer's hard-iron.Spielvogel and Whitcomb later extended this method to include the estimation of gyroscope and accelerometer biases [11].Nevertheless, neither of these arXiv:2410.13827v1[cs.RO] 17 Oct 2024 methods addresses soft-iron magnetometer calibration.
The methods mentioned above are limited to batch calibrations, where all the measurements must be collected in advance.However, it is desirable to perform calibration in the field when pre-calibration is not possible, for instance, due to changes in the vehicle's configuration deployed in highly disturbed environments.Crassidis et al. [12] presented an extension to the TWOSTEP method that incorporates an extended Kalman filter (EKF) and an unscented Kalman filter (UKF).Later, Ma and Jing [13], as well as Soken and Sakai [14] proposed alternative approaches for the UKF method, while Guo et al. [15] presented an alternative EKF method.Additionally, Han et al. [16] and Spielvogel et al. [17] proposed a gyroscope-aided EKF, with the latter also incorporating gyroscope biases in the estimation.
The previously reported approaches have at least one of the following limitations that narrow their implementation scenarios: (i) the requirement to undergo extensive angular motion in all three rotational degrees of freedom, which is often infeasible for devices mounted on full-scale vehicles, such as pitch and roll-stable remotely operated underwater robotic vehicles (ROVs); (ii) the need for accurate knowledge of the local Earth's magnetic field from magnetic field models which may introduce significant errors due to unmodeled local perturbations [18], or (iii) the inability to determine the magnetometer's soft-iron error, i.e., neglect non-orthogonalities and scale factors that affect systems when ferromagnetic materials, such as iron and steel, surround the object, resulting in less accurate output.This paper introduces a novel approach, called MAgnetometer and GYroscope Calibration (MAGYC), which effectively overcomes these challenges.The approach enables two factor graph-based methods and offers several notable advantages, including (i) fewer restrictions on angular movement requirements, (ii) no need for information about the local magnetic field or system's attitude, (iii) a complete calibration for both magnetometer and gyroscope, and (iv) integration into factor graph algorithms for Smoothing and Mapping frameworks with tools such as GTSAM or iSAM [19] for problems such as simultaneous localization and mapping (SLAM).
The paper is structured as follows.Section II briefly overviews the mathematical content.Section III details the proposed MAGYC methods.Section IV describes the evaluation methodology, while Section V reports simulation results, and Section VI presents experimental results.The results and conclusions are summarized in Section VII.
II. MATHEMATICAL BACKGROUND
A. Rotation Matrix
The orientation of an instrument frame V relative to an inertial world frame W can be represented by a rotation matrix R(t) ∈ SO(3) [20,Def. 3.1].
B. Kronecker Product
The Kronecker product of the matrix A ∈ M p×q with the matrix B ∈ M r×s is defined as an p × q block matrix whose (i, j) block is the r × s matrix a ij B [21, Def.2.1].
C. Operators 1) Skew-Symmetric: We denote [ • ] × : R 3 → R 3×3 as the usual skew-symmetric operator [20,Def. 3.7].
2) vec-operator: We denote vec(•) as the vec-operator for any matrix A ∈ M m×n , representing the entries of A stacked columnwise, forming a vector of length m×n [21, Def.2.2].
D. Factor Graphs
Factor graphs are representations of probabilistic or graphical models consisting of nodes representing unknown random variables (x i ∈ X ) and edges representing the dependencies or relationships between these variables.The edges are associated with factors (f i ∈ F), which are probabilistic constraints derived from measurements, prior knowledge, or relationships between variables, and can be categorized as unary factors when connecting to a single node or binary factors if they connect two or more nodes [22]- [24].
The factor graph is a concise and intuitive way of representing a model that is well-suited for performing various types of probabilistic inference tasks, such as bias estimation given a set of measurements for sensor calibration.In comparison to traditional filtering methods, factor graphs have shown superior capability in managing nonlinear processes and measurement models.They offer notable advantages in processing time, flexibility, and modularity, particularly for large-scale and complex optimization problems [25], [26].
Unary and binary factors can be represented as measurement likelihood with a Gaussian noise model [25], which is only evaluated as a function of the unknown state x since the measurement m is considered known
L(x; m) = exp − 1 2 ||h(x) − m|| 2 Σ ,(1)
where h(x) is a nonlinear measurement model, || • || is the Mahalanobis distance, and Σ is the noise covariance matrix.
Utilizing the factors and a prior belief over the unknown variable P (x 0 ), we formulate the joint probability model.Our objective is to determine the optimal set of parameters X * through the maximum a posteriori (MAP) estimate by maximizing the joint probability P (X, Z), leading to a nonlinear least squares problem (2).Leveraging the factor graph structure and sparse connections in this estimation process helps reduce computational complexity [22], [25].
X * ≜ argmax x P (X |Z) = argmin x −log P (X , Z)(2)
III. PROPOSED CALIBRATION APPROACH
In this Section, we propose two methods based on the novel MAGYC method to estimate the complete calibration of a three-axis magnetometer, i.e., hard-iron and soft-iron, and a three-axis gyroscope using magnetometer and angular rate measurements in the instrument frame, i.e., the attitude of the instrument is not required.
A. Sensor Error Model
As detailed in Section I, magnetometers can exhibit biases referred to as hard-iron and soft-iron during operational conditions, leading to potential inaccuracies in their measurements.These biases are assumed to remain relatively constant or change slowly over time, allowing them to be treated as constants.The magnetometer model is given by
m m (t) = A(m t (t) + m b ),(3)
where m m (t) ∈ R 3 is the noise-free magnetic field measurement in the sensor's frame, m t (t) ∈ R 3 is the noise-free magnetic field real value in the sensor's frame, A ∈ R 3×3 is the soft-iron, represented by a constant fully populated positive definite symmetric (PDS) matrix, and m b ∈ R 3 is a constant pseudo-hard-iron, that once scaled by A will give us the magnetometer's hard-iron.
In contrast, gyroscopes are affected by the constant sensor bias and can be represented as
w m (t) = w t (t) + w b ,(4)
where w m (t) ∈ R 3 is the noise-free gyroscope measurement in the sensor's frame, w t (t) ∈ R 3 is the noise-free gyroscope real value in the sensor's frame, and w b ∈ R 3 is the constant gyroscope bias.
B. System Model
A magnetometer measures, in instrument coordinates, the Earth's local magnetic field, which is considered to be locally constant and fixed with respect to the inertial world frame of reference.From (3), we can clear the true magnetic field (m t (t)) and convert it to world coordinates given a rotation matrix R.Then, we can differentiate the equation with respect to time, removing the local magnetic field from the system's model, which yields to
Ṙ(A −1 m m (t) − m b ) + RA −1 ṁm (t) = 0.(5)
Using the standard equation [20], and incorporating the gyroscope bias, we derive a more comprehensive AHRS calibration that considers both magnetometer and gyroscope calibrations.This yields a nonlinear system model independent of the instrument's attitude R(t).
Ṙ(t) = R(t) [w(t)] ×[w m (t) − w b ] × (A −1 m m (t)−m b )+A −1 ṁm (t) = 0 (6)
From ( 6), we estimate the soft-iron (A), the pseudohard-iron (m b ), therefore, the hard-iron (Am b ), and the gyroscope bias (w b ), using gyroscope (w m (t)) and magnetometer (m m (t)) measurements.The proposed approach presents two methods based on a pose graph-based approach.While similar implementations using non-linear least squares were analyzed, the factor graph approach demonstrated superior performance.However, due to space constraints, further details regarding this comparison are not included.
C. MAGYC: MAgnetometer and GYroscope Calibration
The proposed method for estimating the calibration parameters adopts a factor graph approach, where a single node represents the state x = [a m b w b ] T , where a = (A 00 A 01 A 02 A 11 A 12 A 22 ) T is the vector of the unique six upper triangular terms of the soft-iron matrix, A. The residual from the non-linear model ( 6) and any additional constraints required are represented as unary factors.
The decision to employ a single node instead of multiple, one for each magnetometer-gyroscope measurement set (i.e., m nodes), is based on the assumption of constant calibration parameters.If multiple nodes were used, a binary factor would be necessary between each state, totaling m − 1 constraints to maintain the constancy of the state vector; however, this is a soft constraint due to the probabilistic nature of the state vector in a factor graph.Modeling the system as a single node ensures one set of calibration values and spares the use of the m − 1 constraints.
As per ( 6), a unary factor can be defined for the residual of each magnetometer-gyroscope measurement pair.The equation for this factor is shown in (7), where h r (x) represents the residual model (6).
L R (x; (z mag , z gyro )) = exp − 1 2 ||h r (x)|| 2 Σ(7)
To use the unary factor in (7), we need to compute the algebraic Jacobian of the residual model.This can be achieved using the Kronecker product and vec-operator, as shown in (8).For conciseness, we do not expand these equations further in this paper.In (8), the matrix C represents the inverse of the soft-iron matrix, the vector c contains the upper triangular terms of matrix C, and i denotes the ith sample.Note that the magnetic field differentiation is not directly available and must be computed numerically.
h ri (x) c = (m i T ⊗ [w i − w b ] + ṁT i ⊗ I 3 ) ∂vec(C) ∂c (8a) h ri (x) m b = [w b − w i ](8b)h ri (x) w b = − ∂ (m i ⊗ [w b ]) ∂w b • vec(C) + ∂[w b ] ∂w b • m b (8c)
To prevent the algorithm from converging to the trivial solution x = 0, which satisfies (6), a constraint can be applied to the unique upper triangular terms of the softiron matrix.This constraint is based on prior knowledge of the soft-iron matrix's proximity to the identity matrix.Specifically, we calculate an error term by measuring the difference between the Frobenius norm of the unique softiron's upper triangular terms and 1.This error is expressed as N (x) = ||c|| F − 1.We introduce a soft-iron norm unary factor (L N ) defined as
L N (x) = exp − 1 2 ||N (x)|| 2 Σ .(9)
The Jacobian of this factor can be found using It is worth noting that the same factors introduced in this paper, namely (7) and (9), can be added to different value nodes in the graph to enable biases to vary over time and be integrated with SLAM graphs.However, this integration is beyond the scope of this paper.
∂N (x) ∂c = c T || c || F . (10) (a) (b) (c)
In the factor graph construction, given a set of m pairs of magnetometer-gyroscope measurements, the factor graph should be composed of a single node for the state vector and 2m factors: m factors from the system model residual (7) and m factors enforcing unitary norm constraints on the unique upper triangular terms of the soft-iron matrix (9).Nevertheless, to reduce the computational load of the graph, we employ an averaging window of size θ, which reduces the unary factors from 2m to 2n, with n = m/θ.By averaging θ measurements before incorporating them into the graph, we can decrease the number of factors and effectively smooth the raw measurements and the movement while filtering out high-frequency noise in the signal, preserving the underlying trend.In this paper, to ensure real-time operation during long-duration tasks, the averaging window's length is set to the sensor's frequency, allowing the factor graph to manage the same period, irrespective of the sensor's frequency.
The factor graph's construction can follow two methods based on implementation scenarios.In the first method, calibration is performed as a post-processing step, where all m measurements are initially collected, and then the optimization process incorporates all 2n factors.The second approach involves constructing the graph incrementally, with factors added as they become available, and optimization occurs after a specified number of factors have been added.
As mentioned earlier in Section II.D, constructing the graph requires solving a nonlinear least squares problem with sparsity properties.To address this challenge, Rosen et al. [27] proposed RISE, an incremental trust-region method designed for robust online sparse least-squares estimation.As demonstrated in [27], compared to current state-of-the-art sequential sparse least-squares solvers, RISE offers improved robustness against nonlinearity in the objective function and numerical ill-conditioning, leveraging recent advancements in incremental optimization for fast online computation.
IV. EVALUATION METHODOLOGY
We compared the performance of five methods for threeaxis magnetometer calibration and, optionally, for three-axis gyroscope calibration.These methods can be divided into batch and real-time solutions, with the proposed methods highlighted in bold.The batch methods are as follows:
1) MAGYC-BFG: The calibration parameters are estimated using the batch mode factor graph approach described in Section III.C, where all the factors are added to the factor graph before optimization.2) TWOSTEP: The calibration parameters are estimated using the widely cited TWOSTEP method [2], which is based on the implementation proposed by Dinale [28].This method takes as input the local value of the magnetic field.3) Ellipsoid Fit: The calibration parameters are estimated using the widely used Ellipsoid Fit method, based on the implementation proposed by Bazhin et al. [29].The real-time methods are listed below:
1) MAGYC-IFG: The calibration parameters are estimated using the incremental mode factor graph approach described in Section III.C, where the factors are added as they are received.2) MagFactor3: The calibration parameters are estimated using a factor graph approach that utilizes the magnetic calibration factor provided in the GTSAM library [19].Unlike full soft-iron matrix estimation, this method only estimates a single scale factor that is uniform across all three axes, as well as the hard-iron bias.The current attitude of the system and the local magnetic field value must be provided as inputs.To the best of our knowledge, this is the only factor graph-based method available in the literature that accounts for softand hard-iron biases and does not require a predefined set of movements.To compare batch and real-time methods, the calibration parameters estimated with the real-time methods were based on the average of the last 20 % of the estimated parameters.It should be noted that the TWOSTEP and MagFactor3 methods require knowledge of the local magnetic field magnitude, which was obtained from the World Magnetic Model provided by the National Oceanic and Atmospheric Administration (NOAA) [18] for in-field evaluations.Furthermore, for these methods, we assume the gyroscope is calibrated; however, this has no impact on the methods' performance or evaluation, as neither of them uses the angular rate measurements nor computes the gyroscope bias.
For both numerical and in-field evaluations, for the factor graph-based methods, the termination criteria were also set empirically, with both the relative and absolute error tolerances set to 1.0×10 −7 .A multifrontal Cholesky factorization was used, as it has been shown to outperform the LDL and QR factorizations [25].The optimization was computed using the RISE method from GTSAM.The initial conditions for the state vector are the assumption of both magnetometer and gyroscope to be calibrated, i.e., m b = ⃗ 0 mG, w b = ⃗ 0 mrad/s and a = (1.0 0.0 0.0 1.0 0.0 1.0) T .For MAGYC-IFG and MAGYC-BFG, the factor graph was optimized each time a new pair of factors was added from an averaged sample set i, ∀ i ∈ {0, . . ., n}, with an average window size θ set to match the sensor's frequency.The noise covariance matrices were set to I 3 • 0.001 and I 1 • 0.01 for ( 7) and ( 9), respectively.These values were determined through a sensitivity analysis, which found the optimal trade-off for the matrices.Due to space constraints, the details of this analysis are not included.
V. NUMERICAL SIMULATION EVALUATION
A Monte Carlo numerical simulation was conducted in Python3 running on a 12th-generation Intel Core i7-12800H CPU with 64 GB of memory to replicate 10,000 measurements from a MEMS AHRS during sinusoidal motions of a vehicle.Three simulated datasets represented varying degrees of angular motion constraint in all degrees of freedom.The wide angular movement (WAM) dataset (Fig. 2a) covered a ±180
• range in roll, pitch, and heading.The moderate angular movement (MAM) dataset (Fig. 2b) had ±5 • and ±45
• ranges for roll and pitch, respectively, but the same heading range as WAM.The low angular movement (LAM) dataset (Fig. 2c) retained the roll range while reducing the pitch and heading ranges to ±15 • and ±90 • , respectively.Each experiment lasted 400 s, with simulated data generated at a 25 Hz rate and magnetometer measurements (σ mag = 1 mG) and angular rate sensor (σ gyro = 5 mrad/s) corrupted by Gaussian noise.The true magnetic field vector is given by m 0 = [227, 52, 412] T mG, the softiron upper triangular terms are given by a = [1.10,0.10, 0.04, 0.88, 0.02, 1.22] T , the hardiron bias is m b = [20, 120, 90] T mG, and the gyroscope bias is w b = [4, −5, 2] T mrad/s.To account for the magnetic field's uncertainty from local perturbation, in the TWOSTEP and MagFactor3 methods it was 5 % higher than the value used to generate the simulated data.
The calibration methods presented in Section IV were calibrated on the three datasets mentioned previously and later evaluated on a dedicated unique excited evaluation dataset to avoid overfitting.Results in Table I and Fig. 3a show that the proposed MAGYC methods consistently outperformed the benchmark methods.Specifically, in the WAM dataset calibration, while the TWOSTEP method showed superior performance in hard-iron estimation, both MAGYC-BFG and MAGYC-IFG displayed comparable performance in mean heading Root Mean Squared Error (RMSE) and magnetic field standard deviation.
In the MAM and LAM datasets, TWOSTEP failed to converge, and the Ellipsoid Fit method significantly deteriorated results, highlighting their limitation to wide-range movement scenarios, which may not always be feasible in some full-scale vehicles.Meanwhile, MagFactor3 showed more robustness but did not compute non-orthogonality or scale factors in the three axes.In contrast, the proposed MAGYC methods consistently demonstrated better overall performance.
These results suggest that the MAGYC methods are more resilient to constrained angular movements than state-of-theart methods, particularly in the MAM and LAM datasets that emulate actual operating conditions.Furthermore, the MAGYC methods show consistent performance even under conditions favorable to the benchmark methods, such as in the WAM dataset.Additionally, the MAGYC-BFG method demonstrates greater robustness compared to MAGYC-IFG.Furthermore, in the case of the real-time MAGYC-IFG method, convergence to a constant bias estimation occurs after analyzing 40 % of the data.
Regarding processing time, the MAGYC-IFG method has a computation time of around 0.8 s per calibration for all datasets, demonstrating the feasibility of real-time operation when the averaging window (θ) is set to the sensor's frequency, as proposed in Section III.C, with a factor graph update rate of 1 Hz (one update per second).In contrast, the MAGYC-BFG method shows a slight increase in processing time with a decrease in the movement range, increasing from around 0.3 s to 0.8 s per calibration due to longer iterations required to meet termination criteria; however, this is not critical for operation due to the post-processing use of the MAGYC-BFG method.
These simulation results support that both proposed MAGYC methods show competitive or better performance than the benchmark methods, indicating their effectiveness for post-processing and real-time navigation applications.Furthermore, even though the proposed methods do not significantly improve performance for the WAM dataset, they demonstrate better performance in movement-constrained scenarios (MAM and LAM).
VI. FIELD EXPERIMENTAL EVALUATION
We evaluate the in-field performance of the proposed and benchmark methods using a seafloor mapping survey dive conducted during an oceanographic survey mission in Monterey Bay, where the local magnetic field had a magnitude of 479 mG [18], by the Doc Ricketts ROV, owned and operated by the Monterey Bay Aquarium Research Institute (MBARI), which is equipped with a MEMS Inertial Measurement Unit (IMU).Two field experiments were conducted on the same day.The first experiment denoted as EXP1 (Fig. 4a), is a magnetometer calibration procedure for ROVs, which involved a series of 360 • heading rotations, with the pitch and roll configurations changing to produce 5 • pitch and roll movements.The second experiment denoted as EXP2 (Fig. 4b), consisted of a standard survey where the vehicle maintained a stable pitch and roll, resembling the pattern of "mowing a lawn".To evaluate the heading estimation performance, we used a Vectornav VN100 MEMS-based IMU operating at a sampling rate of 80 Hz, featuring a magnetometer noise level of σ mag = 1 mG and an angular-rate gyroscope noise level of σ gyro = 0.5 mrad/s [30].In field applications, although magnetometers can be calibrated beforehand, once the sensor is mounted on the vehicle, local perturbations can cause unknown magnetometer biases.Therefore, we utilized a Kearfott SeaDeViL high-end Inertial Navigation System (INS) operating at a sampling rate of 25 Hz as the ground truth for heading comparison.The INS includes a ring-laser gyro, providing a precision of 0.05 • and 0.03 • in heading and pitch/roll, respectively [31].We interpolated the MEMS IMU data to the INS sampling time to estimate the vehicle's heading.The heading error, defined as the standard deviation between the measured heading from the INS and the calculated heading from the bias-compensated magnetometer data for each evaluated method, was used as the evaluation metric in order to isolate alignment errors.
As shown in Fig. 3b, the proposed MAGYC methods demonstrate remarkable performance when calibrated using EXP1 and evaluated with EXP2, reducing the original heading error from 6.21 • to 0.57 • .Furthermore, the proposed methods improve the heading error for calibration with EXP2, while the benchmark methods fail to converge to a solution except for MagFactor3, which is still outperformed by both proposed methods, thereby demonstrating the superiority of the proposed methods.The performance of the benchmark methods highlights how these methods are constrained to wide-range movement applications, rendering them unsuitable for full-scale applications.This underscores the capability of the proposed methods for enhancing calibration in highly constrained implementations, as they consistently converge even in challenging scenarios, whether in batch or real-time mode.
VII. CONCLUSIONS
The MAgnetometer and GYroscope Calibration (MAGYC) proposed methods, MAGYC-BFG and MAGYC-IFG, have been demonstrated to significantly improve the performance of AHRS sensors in simulated and in-field scenarios.The results show that the MAGYC methods outperform or are comparable to previously reported methods, such as TWOSTEP, Ellipsoid Fit, and MagFactor3.Notably, in scenarios where the sensor ranges are constrained, such as the simulated datasets MAM and LAM or the field data, TWOSTEP failed to converge while Ellipsoid Fit provided inaccurate calibration, even when precise knowledge of the local magnetic field vector was available in both cases, rendering them unsuitable for full-scale vehicles where extensive angular motions in the three rotational degrees of freedom are unfeasible.Although in these cases MagFactor3 converged, it did not compute non-orthogonality or scale factors in the three axes and was consistently outperformed even when accurate knowledge of the local magnetic field and system attitude was required.In all scenarios, MAGYC methods converged and improved the calibration of the sensors.This underscores the capability of the proposed methods for enhancing calibration in highly constrained implementations, as they consistently converge even in challenging scenarios, whether in batch or real-time mode.
These results highlight the practicality and efficacy of the MAGYC methods proposed in this study for the calibration of magnetometers and gyroscopes, particularly in the context of attitude estimation.The implications of these findings extend to potential advancements in cost-effective navigation systems and enhanced performance for ground, marine, and aerial vehicles in real-world environments.
Fig. 1.Diagram illustrating an underwater vehicle's dead reckoning position using different magnetic field sources for the heading estimation with the corresponding trajectories represented with dashed lines.
Fig. 2 .
2
Fig. 2. Simulated magnetometer data for three datasets: (a) WAM, (b) MAM, and (c) LAM.The 3D plots show blue dots for magnetometer data, gray spheres for the true magnetic field, and orange ellipsoids for the distorted magnetic field.
Fig. 3 .
3
Fig. 3. Evaluation results: (a) Performance comparison of five calibration methods on three simulated datasets.The hard-iron error |m b − m * b |, soft-iron error |A − A * |, and gyroscope bias error |w b − w * b | are analyzed for the WAM (green), MAM (yellow), and LAM (orange) datasets.Red dashed lines indicate instances where the method failed to estimate the parameters for a particular dataset, and gray-shaded zones, show the raw data value.(b) Heading error on field data for calibration parameters estimated with EXP1 and evaluated with EXP2.
Fig. 4 .
4
Fig.4.In-field magnetic data for two datasets: (a) EXP1 and (b) EXP2.The 3D plots show blue dots for magnetometer data and gray spheres for true magnetic field.
TABLE I MEAN
I
HEADING RMSE AND MAGNETIC FIELD STANDARD DEVIATION FOR THREE BATCH AND TWO REAL-TIME CALIBRATION METHODS AND THREE SIMULATED DATASETS OVER 100 VALIDATION SIMULATIONS.N/A INDICATES FAILURE.THE BEST TWO RESULTS IN EACH COLUMN ARE BOLDED
WAM for CalibrationMAM for CalibrationLAM for CalibrationMean HeadingMagnetic Field Mean HeadingMagnetic Field Mean HeadingMagnetic FieldRMSE (deg)Std (mG)RMSE (deg)Std (mG)RMSE (deg)Std (mG)Raw28.86460.33028.86460.33028.86460.330BATCHMAGYC-BFG TWOSTEP Ellipsoid Fit2.659 2.518 18.2329.794 9.421 62.5222.735 N/A 16.2359.875 N/A 60.2113.812 N/A 50.84216.016 N/A 157.802REALTIMEMAGYC-IFG MagFactor32.654 15.9159.762 45.1922.791 16.91710.371 49.6033.528 14.43117.552 48.784
ACKNOWLEDGMENTSThe field experimental data used in this study were collected during the 2014 Ocean Imaging cruise conducted by MBARI, led by Chief Scientist Dr. David Caress.Additionally, we acknowledge Dinale[28]and Bazhin et al.[29]for providing open-source code for the implementation of the TWOSTEP[2]and Ellipsoid Fit methods, respectively.This work was supported by the David and Lucile Packard Foundation and FONDECYT-Chile under grant 11180907.S. Rodríguez-Martínez and G. Troni are with the Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039-9644.{srodriguez,
TWOSTEP: A fast robust algorithm for attitude-independent magnetometer-bias determination. R Alonso, M D Shuster, J. Astronautical Sci. 5042002
Complete Linear Attitude Independent Magnetometer Calibration. R M S Alonso, J. Astronautical Sci. 5042002
A novel calibration method of magnetic compass based on ellipsoid fitting. J Fang, H Sun, J Cao, X Zhang, Y Tao, IEEE Trans. Instrum. Meas. 6062011
Extension of a two-step calibration methodology to include nonorthogonal sensor axes. C C Foster, G H Elkaim, IEEE Trans. Aerosp. Electron. Syst. 4432008
Complete Calibration of three-axis strapdown magnetometer in mounting frame. H S Ousaloo, G Sharifi, J Mahdian, M T Nodeh, IEEE Sensors J. 17232017
Geometric approach to strapdown magnetometer calibration in sensor frame. J F Vasconcelos, G Elkaim, C Silvestre, P Oliveira, B Cardeira, IEEE Trans. Aerosp. Electron. Syst. 4722011
Magnetometer calibration using inertial sensors. M Kok, T B Schon, IEEE Sensors J. 16142016
Computationally efficient calibration algorithm for three-Axis accelerometer and magnetometer. K Papafotis, P P Sotiriadis, Proc. 8th Int. Conf. Modern Circuits and Syst. 8th Int. Conf. Modern Circuits and SystThessaloniki, Greece2019Technol.
A novel magnetometeraccelerometer calibration based on a least squares approach. N Ammann, A Derksen, C Heck, Proc. 2015 Int. Conf. Unmanned Aircraft Syst. 2015 Int. Conf. Unmanned Aircraft SystDenver, CO, USA2015
Field sensor bias calibration with angular-rate sensors: Theory and experimental evaluation with application to magnetometer calibration. G Troni, L L Whitcomb, IEEE/ASME Trans. Mechatron. 2442020
Adaptive sensor bias estimation in nine degree of freedom inertial measurement units: Theory and preliminary evaluation. A R Spielvogel, L L Whitcomb, Proc. nullMadrid, Spain2018. 2018
Real-time attitudeindependent three-axis magnetometer calibration. J Crassidis, K.-L Lai, R Harman, J. Guidance, Control, and Dynamics. 2812005
Unscented Kalman filter for spacecraft attitude estimation and calibration using magnetometer measurements. G Ma, X Jiang, Proc. 2005 Int. Conf. Mach. Learning and Cybern. 2005 Int. Conf. Mach. Learning and CybernGuangzhou, China2005
TRIAD+Filtering approach for complete magnetometer calibration. H Soken, S.-I Sakai, Proc. 2019 9th Int. Conf. Recent Advances in Space Technol. 2019 9th Int. Conf. Recent Advances in Space TechnolIstanbul, Turkey2019
The soft iron and hard iron calibration method using extended kalman filter for attitude and heading reference system. P Guo, H Qiu, Y Yang, Z Ren, Proc. nullMonterey, CA, USA2008. 2008
Extended Kalman filter-based gyroscope-aided magnetometer calibration for consumer electronic devices. K Han, H Han, Z Wang, F Xu, IEEE Sensors J. 1712017
Online three-axis magnetometer hard-iron and soft-iron bias and angular velocity sensor bias estimation using angular velocity sensors for improved dynamic heading accuracy. A Spielvogel, A Shah, L Whitcomb, Field Robotics. 212022
National Oceanic and Atmospheric Administration (NOAA). Feb. 2023The World Magnetic Model
. " Borg Lab, Gtsam, 2023
. K Lynch, F Park, Modern Robotics, 2017. MayCambridge University Press
On the Kronecker Product. K Schäcke, 2013University of WaterlooMaster's thesis
Factor graphs and GTSAM: A hands-on introduction. F Dellaert, Georgia Institute of Technology, Tech. Rep. 2012
Probabilistic graphical models: principles and techniques. D Koller, N Friedman, MIT press2209
Factor graphs and the sum-product algorithm. F R Kschischang, B J Frey, H A Loeliger, IEEE Transactions on Information Theory. 4722001
Square root SAM: Simultaneous localization and mapping via square root information smoothing. F Dellaert, M Kaess, Int. J. Robotics Research. 25122006
UAV Localization Algorithm Based on Factor Graph Optimization in Complex Scenes. J Dai, S Liu, X Hao, Z Ren, X Yang, Sensors. 22152022
RISE: An incremental trust-region method for robust online sparse least-squares estimation. D M Rosen, M Kaess, J J Leonard, IEEE Trans. Robotics. 3052014
Magnetic test facility -sensor and coil calibrations. J P Dinale, 2013University of AdelaideMaster's Thesis
Ellipsoid fit python. A Bazhin, V Vrba, G Zogopoulos-Papaliakos, 2022
VectorNav Technologies. 2023VectorNav, Dallas, TXTech. Rep.VN-100 User Manual
Kearfott SeaDevil INS. 2015Kearfott, Pine Brook, NJTech. Rep.Kearfott Corporation
| [
-0.08254575729370117,
-0.04008933901786804,
-0.12925760447978973,
-0.1567602902650833,
0.10127443075180054,
-0.13066324591636658,
-0.07515579462051392,
0.042727112770080566,
-0.09071251004934311,
0.11303161084651947,
0.08525945246219635,
-0.09879682958126068,
0.22335807979106903,
0.0229682... |
Primordial black hole formation during cosmic phase transitions
17 Jun 2024
Karsten Jedamzik
Laboratoire de Univers et Particules de Montpellier
UMR5299-CNRS
Universite de Montpellier
34095MontpellierFrance
Primordial black hole formation during cosmic phase transitions
17 Jun 20244F19C6A1E4BAA4F65F6E628C4587A57FarXiv:2406.11417v1[astro-ph.CO]
Primordial black holes (PBHs) may be part of the dark matter.It is shown here that PBHs form more easily during cosmic phase transitions.For approximately scale-invariant primordial curvature fluctuations the PBH mass function may therefore leave a record of the thermal history of the early Universe.In particular a peak is expected on the 1.9M⊙ scale due to the cosmic QCD transition.
where in the second equality we have used the horizon mass and in the fourth equality the Friedman equation H 2 = 8πGρ/3.Here G and ρ are gravitational constant and energy density, respectively.It is seen that the overdense matter contained on the horizon scale is close to its own Schwarzschild radius and therefore close to forming a PBH.It is known that the overdensity of a sub-horizon region does not further grow in a radiation dominated Universe , such that a PBH will either form at horizon crossing, or never, since r S < r H during the subsequent evolution.What is the role of pressure forces during PBH formation ?From astrophysics we are used to the concept that an overdense region may only gravitationally collapse if its size is large enough, larger than the Jeans length.This is the case if the pressure response time, i.e. the time for a pressure (sound) wave to travel over the entire overdense region, t p = r/c s , with c s the speed of sound, is larger than the gravitational collapse time scale, t g ≈ 1/ √ Gρ.Using the speed of sound c s = c/ √ 3 of a relativistic gas, as appropriate in a radiation dominated Universe, one may easily derive the Jeans length
r J ≈ c s / Gρ = √ 8π 3 c H ≈ 1.67r H(2)
It is seen that forces due to pressure gradients are important.The PBH formation process is thus a competition between gravity and pressure forces.This implies that during any epochs in the early Universe where pressure forces are reduced due to a varying equation of state, PBHs may form more easily than during a purely radiation dominated Universe.As PBH formation is a rare process, occuring on an exponential tail (cf.Chapter 3), the slightest reduction of the overdensity required to form a PBH, may lead to a very significant enhancement of PBH formation.For an approximately scale-invariant spectrum of pre-existing inflationary curvature perturbations, the PBH mass function should therefore be peaked at the approximate horizon masses during epochs where a softening of the equations of state occurs.
B. Generic First-Order phase Transitions
Consider a generic first order phase transition.During such a transition there is low-energy phase and a highenergy phase of the matter.These phases may coexist at coexistence temperature T c .In thermodynamic equilibrium the quantities p = −(∂E/∂V ) S and T = (∂E/∂S) V , which define pressure p and temperature T , are continuous at temperature T c .Here E, V , and S are energy, volume, and entropy, respectively.During the phase transition, when the system "cools", high-energy phase with energy density ρ h = ρ l + L is converted to low-energy phase, while the system stays at the same temperature T c .Here L is latent heat.Only when all high-energy phase is converted to low-energy phase, will the temperature drop below T c .Borrowing the parametrisation of the MIT model (developed to describe a first order QCD transition) one may write
p l (T ) = 1 3 g l π 2 30 T 4 ; p h (T ) = 1 3 g h π 2 30 T 4 − B(3)ρ l (T ) = g l π 2 30 T 4 ; ρ h (T ) = g h π 2 30 T 4 + B(4)s l (T ) = 4 3 g l π 2 30 T 3 ; s h (T ) = 4 3 g h π 2 30 T 3 .(5)
In the above s is entropy density and g are statistical weights (i.e.essentially the number of relativistic species in a phase).Furthermore the "bag constant" B acts essentially as a vacuum energy density for the high energy phase.
In the QCD case it was introduced to account for the interaction energy associated within the strongly interacting quark-gluon plasma.During the middle of a phase transition the plasma consists of bubbles of one phase surrounded by the other phase.Over suffienctly large regions, i.e. l >> r b , where r b is the typical size of a bubble, one may define an average density and entropy
⟨p⟩ = p l (T c ) = p h (T c ) (6) ⟨ρ⟩ = f l ρ l (T c ) + (1 − f l )ρ h (T c ) (7) ⟨s⟩ = f l s l (T c ) + (1 − f l )s h (T c ) ,(8)
where f l is the fraction of volume existing in the low-energy phase.During the phase transition the pressure and temperature stay constant and the evolution of average energy-and entropy-density is governed by the evolution of the volume fraction f l .It is therefore clear that over sufficiently large regions the effective speed of sound is zero
c ef f S = ∂⟨p⟩ ∂⟨ρ⟩ S ≈ 0 (9)
These arguments of course only apply in thermodynamic equilibrium, and not for super -cooled or -heated phase transitions.Using the constancy for entropy during adiabatic evolution (i.e.sa 3 = constant) as well as Eqs.4,5,7, and 8 one may derive the evolution of average energy density with scale factor a during a first-order phase transition
⟨ρ⟩(a) = a 0 a 3 [ρ h + 1 3 ρ l ] − 1 3 ρ l . (10)
for a b < a < a e with a b and a e the scale factor at the beginning and the end of the phase transition, respectively.It is interesting to note that it is more akin of a dust like phase (i.e.ρ ∼ 1/a 3 ) than a radiation dominated phase (i.e.ρ ∼ 1/a 4 ).During dust like phases density perturbations can grow unhindered by pressure forces.We therefore expect PBH formation during first-order phase transitions to be faciltated due to the absence of pressure forces.The PBH formation process during a short first-order phase transition has been numerically investigated in [3] This general relativistic hydrodynamic simulation of the evolution of a spherical symmetric overdensity shows the formation of a PBH.In Fig. 1 the evolution of the density profile as a function of radial coordinate is shown.A first-order phase transition with c ef f s ≈ 0 has been assumed in the energy density range ρ = 0.5 − 1, as indicated by the dashed lines, and c s = 1/ √ 3 for ρ > 1 and ρ < 0.5 has been adopted.Note that only the inner region of the simulation is shown.It is seen that at late times when the fluctuation is collapsing any matter which reaches ρ l (T c ) from below during the collapse, will go through the entire phase transition, until ρ ≥ ρ h (T c ) as there are no pressure forces to prevent this collapse.This bias gives the fluctuation the extra kick to form a PBH.In comparison, the dotted lines show the evolution of the density profile in the absence of a first-order phase transition, where for the same initial fluctuation no PBH is formed.
C. QCD phase transition
In the seventies when nuclear physicists discovered a large number of nuclear resonances, it was speculated that the associated softening of the equation of state could lead to an enhancement of PBH formation [4].With the discovery of quantum chromo-dynamics it became clear that nuclear resonances were not the fundamental particles, but were made up of quarks and gluons.For a long time it was thought that the necessary transition from hadronic matter (mesons and baryons) to their constituents (quarks and gluons) at T ∼ 100 MeV could be a first-order phase transition.It was speculated that the softening of the equation of state could lead to an enhancement of solar mass PBHs and potentially explain the MACHO signal of some compact dark matter in the Milky Way halo [5,6]. 1etailed lattice gauge simulations in this millenium [10,11] seem to have established that the QCD transition is no phase transition but a cross-over.There is nevertheless a reduction of speed of sound during the crossover.Fig. 2 shows the relativisitic degrees of freedom g for cosmic temperatures which include the electroweak-and QCD-phase transitions.It also associates the horizon, i.e. the approximated PBH mass, with cosmic temperature.It is seen that during the QCD transition g drops from g ≈ 80 to g ≈ 11.In Fig. 3 and w occurs, as rest mass energy does not contribute to pressure.Only when T has dropped signifantly below M , thereby provoking the annihilation of massive particles with their anti-particles, will c 2 s bounce back to its radiation dominated value.This is the case for the massive gauge bosons W and Z during the electroweak transition, massive pions shortly after the QCD transition and massive electrons and positrons during Big Bang nucleosynthesis.
FIG. 2. The statistical weights for energy density g eff = 30ρ/(π 2 T 4 ) and entropy density h eff = 45s/(2π 2 T 3 ) as a function of cosmic temperature T and horizon mass M h (T ).Kindly provided by the authors of [12].FIG. 3. The speed of sound squared c 2 s and w = p/ρ in the early Universe for a wide range of temperatures.Taken from [13].
The detailed equation of state has been used to compute the density (or curvature) threshold δ c at each epoch required for PBH formation.Pre-existing fluctuations with δ ≥ δ c form PBHs upon horizon crossing, whereas fluctuations with δ < δ c are dispersed by pressure forces (cf.Chapter 5).These studies have been done by either approximate analytical collapse models [14,15] or by full numerical simulation [13,16].In Fig. 4 the PBH formation threshold δ c relative to the threshold in a purely radiation dominated Universe is shown.The underlying study [13] used fully general-relativistic hydrodyamics simulations of spherical fluctuations with different fluctuation profiles (given by the value α).Only the QCD epoch is shown, leading, however, to a comparatively large range in horizon masses (∼ PBH masses).It is seen that the ∼ 30% reduction in c 2 s leads to a ∼ 10% reduction in threshold δ c .This study finds that for a wide range of curvature fluctuations, the apparent horizon aways occurs first in conditions when matter is at the minimum c 2 s .We have observed similar results for first order phase transitions in the previous section.It is also observed that critcal scaling phenomena (Chapter 5) hold even in the QCD case with a varying equation of state, albeit with a different exponent than that in a plasma with a purely radiation dominated Universe.
The results shown in Fig. 4 may be used to compute the QCD PBH mass function as a function of spectral index and fluctuation shape α.The calculations take full account of critical phenomena and apply peaks theory (Chapter 7) for the computation of the PBH mass function.Results are shown in Fig. 5 with the assumption of pre-existing Gaussian fluctuations.It is seen that the resulting peak in the mass function, which is at M ≈ 1.9M ⊙ , is surprisingly independent of the fluctuation shape parameter α and spectral index n s of the underlying fluctuations.Of course the latter holds only when the fluctuations are approximately scale-invariant.For very blue spectra n s > 1 PBH formation is dominated at the smallest scales, and vice versa for very red spectra n s < 1.In such cases the QCD peak would not be very important.But for approximately scale-invariant spectra, PBH formation on the QCD scale M pbh ≈ 1.9M ⊙ is a factor thousand more probable than on other scales.It is also noted that the pion annihilation epoch leads to a small enhancement on mass scales M pbh > 10M ⊙ .Approximately one per cent of all QCD PBHs are thus massive.If some fraction of the observed LIGO/Virgo/Kagra M > M ⊙ events are PBHs [12,17], then gravitational wave detectors have only observed the tip of the iceberg, as there would be a factor ∼ 100 more low mass PBHs.Of course, the obvious smoking gun for the existence of PBH dark matter in our Universe would be the discovery of PBHs of sub-Chandrasekar mass.Such PBHs are formed in QCD enhanced PBH formation scenarios in quite large adundance.
D. The e + e − Annihilation Epoch It has been noted [5,15], that the decrease of w and c 2 s during the e + e − annihilation epoch could lead to an enhancement of the abundance of PBHs on the M pbh ∼ 10 5 M ⊙ scale.However this may not necessarily be the
ρ = i δρ i i ⟨ρ i ⟩ ,(11)
where brackets denote cosmic average and the index i runs over particle species.For adiabatic perturbations one has δρ i = K⟨ρ i ⟩ with K a quantity independent of species, such that δρ/ρ = K.However, the free-streaming of the neutrinos destroys the adiabaticity of the perturbation since δρ ν ≈ 0. Having ⟨ρ ν ⟩/⟨ρ tot ⟩ = g ν /g tot = 5.25/10.75≈ 0.5 one may estimate that the original perturbation has only approximately half of the overdensity after neutrino freestreaming.On the other hand, the critical threshold for PBH formation will not reduce by as much as a factor of two due to the e + e − equation of state, such that the argument would imply that formation of PBHs during any epoch after neutrino coupling is highly suppressed for scale invariant perturbation spectra.Seen from the opposite point of view, even if neutrinos are initially homogeneous, the density perturbation in photons and e + e − would gravitationally attract neutrinos.Since those neutrinos do not even exert pressure, a further reduction of w to w ∼ 0.33/2 would occur, favoring PBH formation.Ref. [13] argues that the first argument may be dominant, suppression of PBH formation.However, only a dedicated simulation of PBH formation with a fluid and free-streaming component could definitely answer this question.The formation of PBHs during the e + e − annihilation is therefore an open question.
FIG. 1 .
1
FIG. 1.The evolution of energy density as a function of radial coordinate for a density fluctuation generated during inflation and re-entering the horizon after inflation.Results for two scenarios are shown.(a) a first-order phase transition in the density range ρ = 0.5 − 1 (solid) and (b) a radiation dominated Universe without phase transition (dotted).Figure taken from [3].
the square of the speed of sound c 2 s and w = p/ρ are shown for a wide range of temperatures between T ≈ 25 keV and T ≈ 400 GeV.It is seen that, though the reduction of c 2 s from a value of 1/3 is not as drastic as for a first-order phase transition where c 2 s ≈ 0, that there are several epochs where c 2 s is reduced.Most notable is the reduction during the QCD transition at T ≈ 100 MeV.It is relatively large due to the large number of degrees of freedom involved.Smaller reductions occur during the electroweak transition at T ≈ 100 GeV, the pion annihilation epoch at T ≈ 50 GeV, and the e + e − annihilation epoch at T ≈ 200 keV.During epochs where the plasma contains particles with mass M ∼ T , a generic reduction in c 2
s
FIG. 4 .
4
FIG. 4. The critical threshold for PBH formation during the QCD epoch normalized by the value of a radiation dominated Universe.The parameter α quantifies the shape of the fluctuation.Taken from [13].
The question if there are some massive compact Milky Way halo objects is still under debate, as the EROS[7] and MACHO[8] collaborations find different results. It can, however, be excluded that the Milky way halo is entirely made up of solar mass PBHs, as they would violate microlensing constraints. This conclusion can not be circumvented when the PBHs are members of clusters[9].
. M Crawford, D N Schramm, 10.1038/298538a0Nature. 2985381982
. L J Hall, S Hsu, 10.1103/PhysRevLett.64.2848Phys. Rev. Lett. 6428481990
. K Jedamzik, J C Niemeyer, 10.1103/PhysRevD.59.124014arXiv:astro-ph/9901293Phys. Rev. D. 591240141999
. G F Chapline, 10.1103/PhysRevD.12.2949Phys. Rev. D. 1229491975
. K Jedamzik, 10.1103/PhysRevD.55.R5871arXiv:astro-ph/9605152Phys. Rev. D. 5558711997
. K Jedamzik, 10.1016/S0370-1573(98)00067-2arXiv:astro-ph/9805147Phys. Rept. 3071998
EROS-2). P Tisserand, 10.1051/0004-6361:20066017arXiv:astro-ph/0607207Astron. Astrophys. 4692007
. C Alcock, MACHO)10.1086/309512arXiv:astro-ph/0001272Astrophys. J. 5422000
. M Petač, J Lavalle, K Jedamzik, 10.1103/PhysRevD.105.083520arXiv:2201.02521Phys. Rev. D. 105835202022astro-ph.CO
. T Bhattacharya, 10.1103/PhysRevLett.113.082001arXiv:1402.5175Phys. Rev. Lett. 113820012014hep-lat
. S Borsanyi, 10.1038/nature20115arXiv:1606.07494Nature. 5392016hep-lat
. J I Juan, P D Serpico, G Franco Abellán, 10.1088/1475-7516/2022/07/009arXiv:2204.07027JCAP. 0792022astro-ph.CO
. I Musco, K Jedamzik, S Young, arXiv:2303.079802023astro-ph.CO
. C T Byrnes, M Hindmarsh, S Young, M R S Hawkins, 10.1088/1475-7516/2018/08/041arXiv:1801.06138JCAP. 08412018astro-ph.CO
. B Carr, S Clesse, J Garcia-Bellido, F Kuhnel, arXiv:1906.082172019astro-ph.CO
. A Escrivà, E Bagui, S Clesse, 10.1088/1475-7516/2023/05/004arXiv:2209.06196JCAP. 0542023astro-ph.CO
. G Franciolini, I Musco, P Pani, A Urbano, 10.1103/PhysRevD.106.123526arXiv:2209.05959Phys. Rev. D. 1061235262022astro-ph.CO
| [
-0.16128215193748474,
-0.07756468653678894,
0.06750893592834473,
0.0938032865524292,
0.08727088570594788,
0.09215228259563446,
-0.05746600776910782,
0.06682711839675903,
0.08599579334259033,
-0.08231599628925323,
-0.04806382954120636,
-0.18033882975578308,
-0.07742290198802948,
-0.09899534... |
Maslov Index, Spectral Flow and Bifurcation of Electromagnetic Geodesics Within an Energy Level
22 Aug 2024
Henrique Vitório henrique.vitori@ufpe.br
Departamento de Matemática
Universidade Federal de Pernambuco
Brazil
Maslov Index, Spectral Flow and Bifurcation of Electromagnetic Geodesics Within an Energy Level
22 Aug 2024884F48638AE20E311B429E806BC8D2BFarXiv:2310.17400v3[math.CA]
We develop appropriate notions of Maslov index and spectral flow for electromagnetic geodesics within a fixed energy level and prove a Morse Index type theorem in this context.This is then applied to the problem of electromagnetic geodesics, all of whose energy are the same, bifurcating from a given one.
Introduction
Let M be a n−dimensional smooth manifold endowed with both a semi-Riemannian metric g and a closed 2−form σ.Let also Y : T M → T M be the endomorphism field on M defined via σ(p)[u, v] = g(p)[u, Y (p) [v]].We consider in this work the following system of second order differential equations on M ,
D dt γ = Y (γ)[ γ],(1)
for D/dt the semi-Riemannian covariant derivative.In case g is Riemannian, resp.Lorentzian, these equations govern the motion of a particle on (M, g) under the influence of the magnetic, resp.electromagnetic, field σ.
In the general case of an arbitrary semi-Riemannian metric g, we shall use the term electromagnetic.The endomorphism Y is known as the Lorentz force of the electromagnetic field σ and Eq.(1) as the Lorentz force equation.
We shall call solutions to Eq. (1) electromagnetic geodesics.As it is well-known, along an electromagnetic geodesic γ : I ⊆ IR → M the energy
E(γ, γ) = 1 2 g(γ)[ γ, γ]
stays constant.In this work we are interested in the following phenomenon:
Definition 1.1.Let γ : [0, T ] → M be an electromagnetic geodesic with energy κ.We say that an instant t 0 ∈ (0, T ] is an energy-constrained bifurcation instant for γ if there exists a sequence γ n : [0, T ] → M of distinct electromagnetic geodesics departing from γ(0) and a sequence of distinct instants (t n ) n≥1 in (0, T ] such that 1. t n → t 0 as n → ∞;
2. γ n (t n ) = γ(t n ) for all n;
3. γn (0) → γ(0) as n → ∞;
4. γ n has energy κ for all n.
This kind of qualitative behavior of solutions to variational problems arising in differential geometry, along with its variations, has been the object of study of many works, including [17,10,16,14,11].Bifurcation phenomena are natural to consider.For example, a slight variation of the above definition, in the context of light-like geodesics of a Lorentzian manifold, can be used to model the relativistic phenomenon of gravitational lensing (see [10]).Considering a bifurcation perspective has also provided valuable insights to the study of solutions to some important problems in multidimensional variational calculus; for an updated overview, we refer to the survey [6].
The novelty in our work is the energy constraint expressed in 4. of Definition 1.1.This constraint is a very natural one since the dynamics of a Hamiltonian flow can change significantly from one energy level to another.Moreover, such a constraint may convey a physical meaning to the problem.For example, for (M, g) a space-time, the constraint E(γ n , γn ) = −1/2 means that the trajectories γ n are parametrized by proper time; we remark that, in this context, a bifurcation result for timelike electromagnetic geodesics parametrized by proper time, and departing from a timelike curve representing an observer, was obtained in [11] by exploring the Kaluza-Klein correspondence and resorting to (a stronger form of) the bifurcation result for lightlike geodesics in [10].
In the absence of the energy constraint, sufficient conditions for existence of bifurcation have been obtained in [17], [16] and [14] for the Euler-Lagrange equations associated to the geodesic, electromagnetic and perturbed geodesic Lagrangians L : T M → IR, respectively.These were achieved by proving a Morse Index type theorem and then applying to the action functional of L the functional analytic results for bifurcation of critical points of strongly indefinite functionals established in [8].Observe that since we are allowing for a non-exact electromagnetic field σ, Eq. ( 1) might not be the Euler-Lagrange equations of some Lagrangian function on T M .Nevertheless, the analysis of the electromagnetic geodesics in the vicinity of a given one γ : [0, T ] → M connecting two points p and q, and having the same energy as γ, can also be brought to the realm of critical point theory thanks to the following (see [2] and Sec. 4 below): the solutions γ : [0, T ] → M to Eq. ( 1) connecting two points p and q and constrained to E(γ, γ) = κ correspond to the zeros of a certain smooth 1−form η κ on Ω p,q ([0, 1]) × IR + , where Ω p,q ([0, 1]) is the Hilbert manifold of (Sobolev regular) curves x : [0, 1] → M connecting p and q.Furthermore, η κ possesses local primitives.
Our purpose is to provide a general sufficient condition for energy-constrained bifurcation to occur by establishing a Morse Index type theorem in the energy-constrained setting.Each electromagnetic geodesic γ : [0, T ] → M with non null energy κ possesses an energy-constrained index form, which is the quadratic form Q κ,σ (γ) given by the second derivative of a local primitive for the 1−form η κ at the critical point corresponding to γ.By analysing the kernel of Q κ,σ (γ) we are led to the following notion of conjugacy along γ (we remark that the same notion of conjugacy was obtained in [11] by different means); in the following, the symbols ∇ and R will denote the Levi-Civita connection and the curvature tensor of the metric g, respectively, with the sign convention R(X, Y
) = [∇ X , ∇ Y ] − ∇ [X,Y ] .
Definition 1.2.Let γ : [0, T ] → M be an electromagnetic geodesic with energy κ ̸ = 0.An energyconstrained Jacobi field along γ is a (smooth) vector field J along γ that satisfies the equation
D 2 dt 2 J + R(J, γ) γ − (∇ J Y )[ γ] − Y D dt J − 1 2κ g D dt J(0), γ(0) Y [ γ] = 0.
An instant t 0 ∈ (0, T ], for which there exists a non-null energy-constrained Jacobi field that vanishes at both t = 0 and t = t 0 will be called an energy-constrained conjugate instant along γ.
Without the energy constraint, we shall use the term ordinary to refer to the well-known analogous concepts.So, for instance, we shall also speak of ordinary Jacobi fields and ordinary conjugacy; these are obtained by erasing the last term of the left-hand side of the above equation.
Let us suppose for the rest of this introduction that γ : [0, T ] → M is an electromagnetic geodesic with non null energy κ.A direct application of the Implicit Function Theorem shows that every energyconstrained bifurcation instant is an energy-constrained conjugate instant.Reciprocally, Theorem 1.5 below establishes that the interval (0, T ] will contain an energy-constrained bifurcation instant for γ provided that the "net number" of energy-constrained conjugate instants in (0, T ] be non null.This net number shall be given by the following notion of energy-constrained Maslov index of γ.For this, let ζ t : T M → T M be the flow corresponding to Eq. ( 1).This flow is the Hamiltonian flow of the energy function E : T M → IR when one endows T M with the symplectic structure ω induced by both the metric g and the electromagnetic field σ, i.e. ω = dα g + π * σ, for α g the pull-back of the canonical 1−form α of T * M by the diffeomorphism g ♯ : T M → T * M and π : T M → M the projection map.Let S be the corresponding Hamiltonian vector field.
Since the energy surface E −1 (κ) is invariant by ζ t , the derivative of ζ t induces an isomorphism of quotient spaces, Φt :
T (p,v) E −1 (κ)/ ⟨S⟩ → T (γ, γ) E −1 (κ)/ ⟨S⟩ ,(2)
where p = γ(0) and v = γ(0).The above quotient spaces inherit from ω a symplectic structure, and the map Φt is symplectic.Let V E −1 (κ) ⊂ T E −1 (κ) denote the vertical distribution on E −1 (κ), which is given by the tangent spaces to the fibers of the projection
E −1 (κ) → M . The image of V E −1 (κ) in T E −1 (κ)/⟨S⟩ is a
Lagrangian subbundle, which we shall denote by L. By pulling L(γ, γ) back by Φt we thus obtain a curve of Lagrangian subspaces,
ℓ : [0, T ] → Λ T (p,v) E −1 (κ)/⟨S⟩ , ℓ(t) = ( Φt ) −1 L(γ, γ) .(3)
In the above, Λ(−) denotes the Lagrangian Grassmannian manifold of all Lagrangian subspaces of the corresponding symplectic vector space.
Definition 1.3.The energy-constrained Maslov index of γ, denoted by µ κ (γ), is defined as the Maslov index of the Lagrangian path ℓ| [ϵ,T ] with respect to the reference Lagrangian L(p,v) , for ϵ any sufficiently small positive number (in the sense of Proposition 6.7).
On the other hand, by traveling along γ from p = γ(0) to q = γ(T ), the resulting family of energyconstrained index forms can be identified to a path of quadratic forms Q = {Q s } s∈(0,T ] on the Hilbert space
H 1 0 ([0, 1], IR n ) × IR which are of Fredholm type.
For such a family one can compute the so-called spectral flow along an interval [a, b] ⊂ (0, T ], denoted by sf(Q, [a, b]).Roughly, it gives the net number of the eigenvalues of the self-adjoint operator L s representing Q s that cross zero as s runs from a to b.The spectral flow is an important homotopy invariant which substitutes the notion of Morse index when the later fails to be finite, and plays a key role in strongly-indefinite problems.For instance, the spectral flow is a key to understanding variational bifurcation of strongly-indefinite functionals.Indeed, the main result of [8] shows that the non vanishing of the spectral flow implies bifurcation.We define the energy-constrained spectral flow of γ, and denote it by sf κ (γ), as the spectral flow sf(Q, [ϵ, T ]) for any sufficiently small positive ϵ (as in Proposition 6.7).The Morse Index type theorem that we shall prove establishes that the spectral flow, which is infinite-dimensional in nature, can be computed as the more tractable Maslov index: Theorem 1.4.Suppose that T is neither an energy-constrained nor an ordinary conjugate instant along γ.Then, we have an equality
sf κ (γ) = −µ κ (γ).
This theorem is the energy-constrained version of the Morse Index theorem of [16] which establishes an analogous equality for the ordinary Maslov index µ(γ) and spectral flow sf(γ) of an electromagnetic geodesic.Its proof shall consist in three steps.First we compute the difference sf κ (γ) − sf(γ) by establishing in Sec.3.2 a general formula relating the spectral flow of a path {Q s } to the spectral flow of the path obtained by restricting the Q s to a fixed closed finite codimensional subspace of the ambient Hilbert space.This result extends to general paths (but with invertible endpoints), and with a considerable simpler proof, Theorem 4.4 of [5] proved for paths that are compact perturbations of a fixed symmetry, and might be of independent interest.In the second step, by regarding the Lagrangian path ℓ(t) as the symplectic reduction of another Lagrangian path ľ(t), this time on Λ(T (p,v) T M ), we resort to a result from [19] to equate µ κ (γ) to a Maslov index of ľ(t).This has the advantage that the latter Maslov index differs from µ(γ) by a Hörmander four-fold index, which in turn is half the difference of two Kashiwara indices of triplets of Lagrangian subspaces.So step three shall consist of computing the Kashiwara indices of the triplets formed by the endpoints of the path ľ(t) and the reference Lagrangians.With the computations of sf κ (γ) − sf(γ) and µ κ (γ) − µ(γ) at hand, Theorem 1.4 will follow from the Morse index theorem of [16].
As a consequence of Theorem 1.4 and the criterion for variational bifurcation of strongly-indefinite functionals from [8], we shall obtain the following criterion for energy-constrained bifurcation of electromagnetic geodesics.
Theorem 1.5.Suppose that T is neither an energy-constrained nor an ordinary conjugate instant along γ.If µ κ (γ) ̸ = 0, then there exists an energy-constrained bifurcation instant for γ in (0, T ].
For an isolated energy-constrained conjugate instant t 0 along γ, the energy-constrained Maslov index of γ across t 0 , denoted by µ κ (γ, t 0 ), is defined as the Maslov index of the Lagrangian path ℓ| [t0−ϵ,t0+ϵ] with respect to the Lagrangian L(p,v) , for ϵ a sufficiently small positive number.
Corollary 1.6.An isolated energy-constrained conjugate instant t 0 will be an energy-constrained bifurcation instant provided that µ κ (γ, t 0 ) ̸ = 0.
For an energy-constrained conjugate instant t 0 we consider the subspace J ′ [t 0 ] of T γ(t0) M formed by the values DJ/dt| t=t0 , for J varying among the energy-constrained Jacobi fields vanishing at both t = 0 and t = t 0 .Also, let g t0 be the quadratic form on T γ(t0) M given by
g t0 [u, v] = g(γ(t 0 ))[u, v] − 1 2κ g(γ(t 0 )) γ(t 0 ), u g(γ(t 0 )) γ(t 0 ), v .
We say that t 0 is non-degenarate if the restriction of g t0 to J ′ [t 0 ] is non-degenerate.For such an instant we shall show in Proposition 6.6 that µ κ (γ, t 0 ) is equal to the signature (see (4) below) of the restriction of g t0 to J ′ [t 0 ].Therefore, Corollary 1.7.A non-degenerate energy-constrained conjugate instant along γ with sig g t0 | J ′ [t0] ̸ = 0 is an energy-constrained bifurcation instant.
The paper is organized as follows: in Sec. 2 we recall the definition and basic properties of the Maslov index.In particular, in Sec.2.1 we define the Kashiwara index and sketch the proof of its relation with the difference of Maslov indices.The general notion of spectral flow, as well as of variational bifurcation, is discussed in Sec. 3. In particular, we prove in Sec.3.2 a result for the spectral flow of a restriction to a closed finite codimensional subspace.The necessary variational setup for the problem of electromagnetic geodesics is established in Sec. 4, and energy-constrained Jacobi fields and conjugacy are considered in Sec. 5.In Sec. 6 we describe the energy-constrained conjugacy under a symplectic point of view by first identifying a natural pre-symplectic structure which is preserved by the energy-constrained Jacobi equation, and then showing that a quotient of that equation is symplecticaly equivalent to the flow (2).The definition of the energy-constrained spectral flow of an electromagnetic geodesic is carried out in Sec.7 along with the proof of the necessary analytic facts.At last, the proofs of Theorem 1.4, Theorem 1.5 and Corollary 1.6 are carried out in Sec. 8.
The Maslov index of a curve of Lagrangian subspaces
Let (V, ω) be a finite-dimensional real symplectic vector space.The manifold of Lagrangian subspaces of V , the Lagrangian Grassmannian, shall be denoted by Λ(V ).We shall here recall the definition of the Maslov index of a continuous path ℓ : [a, b] → Λ(V ) with respect to a given reference Lagrangian L 0 ∈ Λ(V ) through a uniqueness result from [18].
Given a pair (L 0 , L 1 ) of transversal Lagrangian subspaces, a chart for Λ(L) around L 0 is obtained as follows.Firstly, given L ∈ Λ(V ), let us denote Λ 0 (L) = {L ′ ∈ Λ(V ) : L ∩ L ′ = {0}}; this is an open and dense subset of Λ(V ).Now, every L ∈ Λ 0 (L 1 ) is the graph of a unique linear map T : L 0 → L 1 such that the bilinear form on L 0 defined by ω
[T •, •] | L0 is symmetric. A chart around L 0 is then obtained by setting φ L0,L1 : Λ 0 (L 1 ) → B sym (L 0 ), φ L0,L1 (L) = ω [T •, •] | L0 ,
where B sym (L 0 ) is the space of symmetric bilinear forms on L 0 .The Maslov index of ℓ : [a, b] → Λ(V ) with respect to L 0 is the semi-integer µ L0 (ℓ) characterized by the following uniqueness result (Corollary 5.2.4 of [18]).Before proceeding, recall that the signature of a (real) quadratic form Q, denoted sig Q, is the difference between the indices of −Q and Q, sig
Q = ind(−Q) − ind Q. (4)
Theorem 2.1.Given a Lagrangian L 0 ∈ Λ(V ), there exists a unique function that assigns to each continuous path ℓ : [a, b] → Λ(V ) a semi-integer µ L0 (ℓ) and that satisfies 1. µ L0 is invariant under homotopies that fix endpoints, 2. µ L0 is additive by concatenation,
3. if ℓ([a, b]) ⊂ Λ 0 (L 1 ) for some L 1 ∈ Λ 0 (L 0 ), then µ L0 (ℓ) = 1 2 sig φ L0,L1 (ℓ(b)) − 1 2 sig φ L0,L1 (ℓ(a)). (5)
Although the above definition of Maslov index allows for paths with endpoints not in Λ 0 (L 0 ), we shall only be interested in the case where ℓ(a), ℓ(b) ∈ Λ 0 (L 0 ) so that µ L0 (ℓ) will in fact be an integer.The Maslov index µ L0 (ℓ) is a sort of counting of intersections of the path ℓ with the Maslov cycle (with vertex L 0 ) Σ(L 0 ) = {L ∈ Λ(V ) : L ∩ L 0 ̸ = {0}}.If t 0 is an isolated instant of intersection, the Maslov index across t 0 , which we denote by µ L0 (ℓ, t 0 ), is defined as
µ L0 (ℓ, t 0 ) = µ L0 ℓ| [t0−ϵ,t0+ϵ] ,
for ϵ sufficiently small; the properties of µ L0 guarantee that µ L0 (ℓ, t 0 ) is well-defined.Let now ℓ : [a, b] → Λ(V ) be of class C 1 .Each velocity vector l(t) = dℓ/dt identifies to a symmetric bilinear form on ℓ(t) as follows.Given t 0 and u, v ∈ ℓ(t 0 ), let u : (t 0 − ϵ, t 0 + ϵ) → V be of class C 1 with u(t) ∈ ℓ(t) for all t and u(t 0 ) = u.
Then one sets l(t 0 )[u, v] = ω [ u(t 0 ), v] .
An instant t 0 of intersection of ℓ with Σ(L 0 ) is said to be non-degenerate if the quadratic form l(t 0 ) is non-degenerate on ℓ(t 0 ) ∩ L 0 .We define the signature of such an instant, sig(ℓ, L 0 , t 0 ), as the signature of the restriction of l(t 0 ) to ℓ(t 0 ) ∩ L 0 .In a vicinity of a non-degenerate instant of intersection with Σ(L 0 ) there are no other instants of intersections, and one shows that µ L0 (ℓ, t 0 ) = sig(ℓ, L 0 , t 0 ).
Thus, for ℓ having only non-degenerate instants of intersection with Σ(L 0 ), and with endpoints in Λ 0 (L 0 ), the Maslov index is the sum of the corresponding signatures:
µ L0 (ℓ) = t∈[a,b]
sig(ℓ, L 0 , t).
2.1
The Kashiwara index of a triplet of Lagrangians.
Given a continuous path ℓ : [a, b] → Λ(V ) and two Lagrangians L 0 , L 1 ∈ Λ(V ), it turns out that the difference of Maslov indices µ L1 (ℓ) − µ L0 (ℓ) only depends on the quadruplet (L 0 , L 1 , L 2 , L 3 ), where L 2 = ℓ(a) and L 3 = ℓ(b).That number, known in the literature as the Hörmander four-fold index of (L 0 , L 1 , L 2 , L 3 ), can be described as half the difference of two Kashiwara indices: given a triplet (L ′ 1 , L ′ 2 , L ′ 3 ) of Lagrangians, its Kashiwara index (called in [13] the Maslov index of the triplet) τ (L ′ 1 , L ′ 2 , L ′ 3 ) is the integer defined as the signature of the quadratic form
Q on L 1 ⊕ L 2 ⊕ L 3 given by Q [(v 1 , v 2 , v 3 )] = ω[v 1 , v 2 ] + ω[v 2 , v 3 ] + ω[v 3 , v 1 ]. Then one has that µ L1 (ℓ) − µ L0 (ℓ) = 1 2 τ (L 1 , L 0 , L 3 ) − 1 2 τ (L 1 , L 0 , L 2 ). (6)
The above equality is implicit in page 181 of [7] when the path ℓ has endpoints transversal to both L 0 and L 1 , and is stated in [12] in the non-transversal case but with a definition of the Maslov index that differs from ours (we should observe, however, that the claimed relation in [12] does not seem to work since the authors' definition of µ L0 (ℓ) does not change the sign when one changes ω by −ω).
Proof of (6) (sketch).Very briefly, the proof of ( 6) is as follows: first one observes that, regarding the right-hand side of ( 5), one has sig φ L0,L1 (ℓ(a)) = τ (L 0 , L 1 , ℓ(a)) and sig φ L0,L1 (ℓ(b)) = τ (L 0 , L 1 , ℓ(b)); this is basically the assertion of Lemma 1.5.4 of [13].Then, given ℓ and L 0 and L 1 , one finds a partition
a = t 0 < t 1 < • • • < t N = b of [a, b] and Lagrangians L ′ 1 , ..., L ′ N ∈ Λ 0 (L 0 ) ∩ Λ 0 (L 1 ) such that ℓ([t i−1 , t i ]) ⊂ Λ 0 (L ′ i ) for all i.
From the properties of the Maslov index stated in Theorem 2.1 and the above observation, one obtains
µ L1 (ℓ) − µ L0 (ℓ) = 1 2 N i=1 (τ (L 1 , L ′ i , ℓ(t i )) − τ (L 1 , L ′ i , ℓ(t i−1 ))) − 1 2 N i=1 (τ (L 0 , L ′ i , ℓ(t i )) − τ (L 0 , L ′ i , ℓ(t i−1 ))) .
The equality in ( 6) is then obtained from the above by exploring the chain condition satisfied by τ (Proposition 1.5.8 of [13]) as well as the antisymmetry of τ .
The spectral flow and bifurcation
Throughout this section, H shall denote a separable infinite dimensional real Hilbert space.We shall use superscript ⊥ to denote the orthogonal complement of a subspace and, given a quadratic form Q on H, the superscript ⊥ Q shall denote the orthogonal complement with respect to Q.
Generalities on the spectral flow.
Let F = F(H) be the space of self-adjoint Fredholm operators on H.The space F has three connected components, F+ , F− and F * .The components F± consist on the operators in F that are essentially positive, resp.essentially negative, (i.e., that have finite dimensional negative, resp.positive, spectral subspaces) and are contractible.As for F * , it has infinite cyclic fundamental group; operators in F * are called strongly indefinite.
Let L = {L s } s∈[a,b] be a continuous path in F; equivalently, via Riez representation, we can consider the corresponding path
Q = {Q s } s∈[a,b] of quadratic forms of Fredholm type on H. The spectral flow of L, or of Q, is the integer sf(L, [a, b]), or sf(Q, [a, b]
), giving the net number of eigenvalues of L that cross 0 in the positive direction as s runs from a to b.While for paths in F+ or in F− this definition can trivially be made precise, for paths in F * it requires some effort.There are several approaches in the literature that produce the same definition of sf(L, [a, b]) if L has invertible endpoints L a and L b (which is the case we shall be considering); see, for instance, [4, Sec.7], [15] and [8].We shall content ourselves with listing here a few properties of sf(L, [a, b]) that we shall make use.
1. (Normalization) If L s is invertible for all s, then sf(L, [a, b]) = 0; 2. if L is a path in F+ with invertible endpoints, then sf(L, [a, b]) = ind L a − ind L b ; 3. (Additivity under concatenation) if L 1 * L 2 is the concatenation of two paths L 1 = {(L 1 ) s } s∈[a,b] and L 2 = {(L 2 ) s } s∈[b,c] that agree for s = b, then sf(L 1 * L 2 , [a, c]) = sf(L 1 , [a, b]) + sf(L 2 , [b, c]);
4. (Additivity under direct sum) if L 1 and L 2 are two paths of self-adjoint Fredholm operators on Hilbert spaces
H 1 and H 2 , then sf(L 1 ⊕ L 2 , [a, b]) = sf(L 1 , [a, b]) + sf(L 2 , [a, b]); 5. (Invariance under cogredience) given a path L in F(H) and a path M = {M s } in GL(H), then sf(L, [a, b]) = sf(M * LM, [a, b]); 6. (Compact perturbations of closed paths) for closed paths, sf(L, [a, b]) is stable under compact perturba- tions: if L is closed and K = {K s } s∈[a,b] is a closed continuous path of compact self-adjoint operators, then sf(L, [a, b]) = sf(L + K, [a, b]).
3.2
The spectral flow of a restriction to a subspace.
Let Q = {Q s } s∈[a,b]
be a continuous path of quadratic forms of Fredholm type on H. Let V ⊂ H be a closed finite codimensional subspace and denote by
Q = {Q s } s∈[a,b] the path of quadratic forms on V obtained by restricting the Q s to V. It is clear that Q s are also of Fredholm type. We shall compute the difference sf(Q, [a, b]) − sf(Q, [a, b]
) in terms of the endpoints data.The key observation is the following.
Lemma 3.1. Suppose that the path Q is closed. Then sf(Q, [a, b]) = sf(Q, [a, b]).
Proof.Let L s be the self-adjoint operator representing Q s .With respect to the orthogonal decomposition H = V ⊕ V ⊥ , let us write L s in block form as
L s = A s B s B * s C s = A s O O O + O B s B * s C s = N s + K s ,
for N s and K s being the first and second summand above, respectively.Since V ⊥ has finite dimension, the operator K s is compact.Thus, by 6. of Sec.
3.1, sf(L, [a, b]) = sf(N, [a, b]). Also, by 4. we have sf(N, [a, b]) = sf(A, [a, b]).
To conclude, just observe that A s is the self-adjoint operator representing Q s .
Lemma 3.2.The space F * ∩GL(H) of invertible strongly indefinite self-adjoint operators is path-connected.
Proof.Fix an orthogonal decomposition H = H + ⊕ H − with H ± infinite dimensional closed subspaces, and let I be the symmetry on H given by
I(v + + v − ) = v + − v − . Given S ∈ F * ∩ GL(H)
, let us decompose H as the orthogonal sum H = E + ⊕ E − of the positive and negative spectral subspaces of S. Let P ± be the projections onto E ± and let I ′ be the symmetry I ′ = P + − P − .We first connect S to
I ′ through the path [0, 1] ∋ t → (tI + (1 − t)S) • P + + (−tI + (1 − t)S) • P − .
Then we connect I ′ to I as follows.Since H ± and E ± are infinite dimensional separable Hilbert spaces, we can find orthogonal transformations f ± :
E ± → H ± . As the orthogonal group O(H) is connected, we connect I to f + ⊕ f − through a path [0, 1] ∋ t → A t ∈ O(H).
For each t, let P t ± be the projections onto
A t E ± . Then t → P t + − P t − is a path of symmetries connecting I ′ to I. Lemma 3.3. Let s be such that Q s is non-degenerate. Then H = V ⊕ V ⊥ Qs . Proof. We already have V ∩ V ⊥ Qs = {0} since Q s is non-degenerate. By passing to the quotient H/ker Q s , we can also suppose that Q s is non-degenerate. Thus the musical map Q ♯ s : H → H * is an isomorphism that sends V ⊥ Qs onto the annihilator V 0 of V. Therefore dim V ⊥ Qs = dim V 0 = codim V = n. It follows that (V ⊕ V ⊥ Qs )/V ∼ = V ⊥ Qs is a subspace of H/V with dimension n. Hence V ⊕ V ⊥ Qs = H.
Proposition 3.4.Let Q, V and Q be as in the beginning of this section.Suppose that Q and Q have non-degenerate endpoints.Then,
sf(Q, [a, b]) − sf(Q, [a, b]) = ind Q a V ⊥ Qa − ind Q b V ⊥ Q b .(7)
Proof.We shall only consider the case where the Q s are strongly indefinite, the other cases being simpler.
In this case, it is clear that Q s are also strongly indefinite.By the previous lemma, we have H = V ⊕ V ⊥ Qs for s = a, b.So, for s = a, b, by rotating V ⊥ Qs to V ⊥ while keeping V fixed, we can connect Q s , via a path of non-degenerate quadratic forms, to the quadratic form Qs whose block decomposition relative to
H = V ⊕V ⊥ is Qs = Q s O O Q ⊥ s , s = a, b, for some quadratic form Q ⊥ s on V ⊥ which is isometric to Q s | V ⊥ Qs . Next we connect Qb to Q′ b = Q a O O Q ⊥ b ,
via a path of non-degenerate quadratic forms on H, by connecting Q b to Q a via a path of non-degenerate quadratic forms on V while keeping the other blocks unaltered; this is possible because of Lemma 3.2.At last, we connect Q′ b to Qa by connecting, in any way, Q ⊥ b to Q ⊥ a while keeping the other blocks unaltered.We end up with a concatenation of paths,
Q a → Q b → Qb → Q′ b → Qa → Q a , defined, respectively, on intervals [a, b], [b, c], [c, d], [d, e], [e, f ], resulting in a closed path Q ′ = {Q ′ s } s∈[a,f ] . Let Q ′ be the restriction of Q ′ to V. By Lemma 3.1, we have sf(Q ′ , [a, f ]) = sf(Q ′ , [a, f ]). On the other hand, 1. since Q ′ s and Q ′ s are non-degenerate for, respectively, s ∈ [b, d] ∪ [e, f ] and s ∈ [b, f ], then sf(Q ′ , [b, d]) = sf(Q ′ , [e, f ]) = 0 and sf(Q ′ , [b, f ]) = 0;
2. by additivity under orthogonal direct sum (4. of Sec.3.1), and the fact that dim
V ⊥ < ∞, we obtain sf(Q ′ , [d, e]) = ind Q ⊥ b − ind Q ⊥ a
, which in turn is equal to minus the right-hand side of Eq. ( 7) since
Q ⊥ s is isometric to Q s | V ⊥ Qs for s = a, b.
The equality (7) follows now from additivity of the spectral flow under concatenation Remark 3.5.The computation of the difference sf(Q, [a, b]) − sf(Q, [a, b]) was also carried out in the work [5] under the hypothesis that the self-adjoint representation of Q is of the form L s = I + K s for some (fixed) symmetry I and some path K of self-adjoint compact operators.In their formula, degenerate endpoints were also allowed.
Abstract variational bifurcation.
Let F s : N ⊂ H → IR be a family of C 2 −functionals defined on a neighborhood N of the origin, all of which having the origin as a critical point, and depending smoothly (i.e.C 2 ) on the parameter s ∈
[a, b]. A point s 0 ∈ (a, b) is said to be a bifurcation instant for the family {F s } if there exist non-trivial sequences (s n ) n in [a, b] and (u n ) n in N , with n ≥ 1, such that 1. u n is a critical point of F sn for all n; 2. s n → s 0 and u n → 0 as n → ∞.
Suppose further that, for each s, the second derivative at the origin,
Q s = (D 2 F s ) 0 : H × H → IR,
is a quadratic form of Fredholm type.From the Implicit Function Theorem it is clear that if s 0 is a bifurcation instant, then s 0 is a degenerate instant of the family Q = {Q s } s∈[a,b] , i.e., an instant for which the form Q s0 is degenerate.
The main result of [8] is the following sufficient condition for existence of bifurcation (see Theorem 1 of [8]).As in [8], let sf(Q, s 0 ) be the spectral flow of Q across an isolated degenerate instant of Q.This is defined as the spectral flow sf(Q, [s 0 − ϵ, s 0 + ϵ]) for ϵ > 0 such that there is no degenerate instants in [s 0 − ϵ, s 0 + ϵ] besides s 0 .Then a corollary of the above theorem is the following.Corollary 3.7.An isolated degenerate instant s 0 for Q will be a bifurcation instant for the family {F s } provided that sf(Q, s 0 ) ̸ = 0.
The variational setup
In this section we shall establish the (local) variational principle for solutions of Eq. ( 1) under the energy constraint E(γ, γ) ≡ κ and compute the energy-constrained index form of an electromagnetic geodesic γ.
It is important to bear in mind that we shall assume the following dictionary throughout this work:
curve γ : [0, T ] → M ←→ (x, T ), with x : [0, 1] → M, x(t) = γ(tT ) vector field V along γ ←→ vector field V along x, V (t) = V (tT )
4.1 Hilbert manifold of paths.
Let p and q be two fixed points on M (assumed to be connected).With the help of an auxiliary complete Riemannian metric on M one can form the space Ω p,q ([0, 1]) of all curves x : [0, 1] → M connecting p to q that have Sobolev regularity H 1 = W 1,2 .It is well-known that Ω p,q ([0, 1]) has the structure of a Hilbert manifold modeled on the Hilbert space H 1 0 ([0, 1], IR n ), and that each tangent space T x Ω p,q ([0, 1]) identifies to the space of H 1 −regular vector fields V along x vanishing at t = 0 and t = 1.Following Sec.2.1 of [1], a local parametrization around a smooth x * ∈ Ω p,q ([0, 1]) can be constructed as follows: fix a smooth frame E 1 , ..., E n along x * and, with the help of the auxiliary Riemannian metric on M , define the map
ψ : [0, 1] × B n ρ → M, ψ(t, x) = exp x * (t) i x i E i (t) ,(8)
where B n ρ denotes the open ball in IR n of radius ρ and center 0 = (0, ..., 0) T and x = (x 1 , ..., x n ) T .We choose ρ small enough so that ψ(t, •) : B n ρ → M is a diffeomorphism onto an open set for each t.By the continuous inclusion
H 1 0 → C 0 , the subset H 1 0 ([0, 1], B n ρ ) given by the x = x(t) such that x([0, 1]) ⊂ B n ρ is open in H 1 0 ([0, 1], IR n ). A parametrization for Ω p,q ([0, 1]) around x * is then obtained by setting Ψ : H 1 0 ([0, 1], B n ρ ) → Ω p,q ([0, 1]), Ψ(x)(t) = ψ(t, x(t)).(9)
It is clear that Ψ(0) = x * and that the derivative (DΨ) 0 :
H 1 0 ([0, 1], IR n ) → T x * Ω p,q ([0, 1]) is the isomorphism v = (v 1 , ..., v n ) T → V = i v i E i . 4.2 The global 1-form η κ .
Following [2], for each given value κ of the energy we can characterize the solutions γ : [0, T ] → M of Eq. ( 1) with energy κ, and connecting p to q, as the zeros of a certain globally defined 1−form η κ on the manifold Ω p,q ([0, 1]) × IR + , where IR + is the set of positive real numbers.
In general, given a Lagrangian function L : T M → IR, its κ−action functional is the function A L κ : Ω p,q ([0, 1]) × IR + → IR defined by
A L κ (x, T ) = T 1 0 (L(x, ẋ/T ) + κ)dt = T 0 (L(γ, γ) + κ)dt.
For us, L will stand for the semi-Riemannian Lagrangian, L(p, v) = 1 2 g(p) [v, v], and we will drop the superscript L. The A κ is a smooth functional (Lemma 3.1 of [1]).Also, by means of the electromagnetic field σ we define a 1−form τ σ on Ω p,q ([0, 1]) via
τ σ (x)[V ] = 1 0 σ(x) [V, ẋ] dt = T 0 g(γ) V , Y (γ)[ γ] dt, V ∈ T x Ω p,q ([0, 1]).
This 1−form is smooth, as will be clear from the discussion at the end of Sec.4.3.The 1−form η κ on Ω p,q ([0, 1]) × IR + is then defined by η κ = dA κ + π * 1 τ σ where π 1 : Ω p,q ([0, 1]) × IR + → Ω p,q ([0, 1]) is the projection.By a direct computation,
η κ (x, T ) [(V, B)] = − T 0 g(γ) V , D dt γ − Y (γ)[ γ] dt + B κ − 1 T T 0 1 2 g(γ) [ γ, γ] dt , for all (x, T ) ∈ Ω p,q ([0, 1]) × IR + and (V, B) ∈ T (x,T ) Ω p,q ([0, 1]) × IR + = T x Ω p,q ([0, 1]) × IR.
From there one easily sees:
Proposition 4.1.A curve γ : [0, T ] → M connecting p to q is an electromagnectic geodesic with energy κ if, and only if, the 1−form η κ vanishes at (x, T ).
The local magnetic κ−action functional.
What is important to us is that the 1−form τ σ , and therefore the 1−form η κ , possesses a local primitive.Given a smooth x * ∈ Ω p,q ([0, 1]), let O ⊂ Ω p,q ([0, 1]) be the neighborhood of x * covered by the parametrization Ψ in (9).Following [3], a primitive for τ σ defined on O can be obtained by setting
C σ,x * : O → IR, C σ,x * (x) = [0,1]×[0,1] (c x * ,x ) * σ,
where c x * ,x = c x * ,x (s, t) : [0, 1] × [0, 1] → M is any map such that s → c x * ,x (s, •) is a smooth path connecting x * to x in O; that C σ,x * is well-defined, smooth and that dC σ,x * = τ σ can be seen from the expression on a local parametrization worked out below.The corresponding primitive for η κ on the neighborhood O × IR + of {x * } × IR + is then
A κ,σ,x * : O × IR + → IR, A κ,σ,x * (x, T ) = A κ (x, T ) + C σ,x * (x).
We shall call A κ,σ,x * the local magnetic κ−action functional (centered at x * ).Then, from Proposition 4.1, Corollary 4.2.A curve γ : [0, T ] → M such that the corresponding x is in O is an electromagnetic geodesic with energy κ if, and only if, (x, T ) is a critical point of A κ,σ,x * .
In order to establish the smoothness of a construction in Sec.8.5, we shall now work out the expression of C σ,x * in the parametrization Ψ.Let ψ : [0, 1] × B n ρ → M be the map in the definition of Ψ.Since dσ = 0, there exists a smooth 1−form θ on
[0, 1] × B n ρ such that ψ * σ = dθ. Given x ∈ H 1 0 ([0, 1], B n ρ ) and a smooth path [0, 1] ∋ s → x s ∈ H 1 0 ([0, 1], B n ρ
) connecting the origin 0 to x, let F = F (s, t) be the map F (s, t) = (t, x s (t)).Since F (s, 0) and F (s, 1) are constant and F (0, t) = (t, 0) we obtain that
(Ψ * C σ,x * )(x) = [0,1]×[0,1] F * dθ = 1 0 θ(t, x) [(1, ẋ)] dt − 1 0 θ(t, 0)[(1, 0)]dt. (10)
It is clear from this that C σ,x * is well-defined and smooth.Observe also that integrating the 1−form Ψ * τ σ along the path s → x s one obtains (Ψ * C σ,x * )(x).This shows that τ σ is smooth with τ σ = dC σ,x * in O.
4.4
The energy-constrained index form.
Let now (x, T ) be a critical point of A κ,σ,x * : O × IR + → IR.Recall that the functional A κ,σ,x * will then possess an intrinsic second derivative at (x, T ), which is a symmetric bilinear form (D 2 A κ,σ,x * ) (x,T ) on the tangent space T x Ω p,q ([0, 1]) × IR whose quadratic form can be computed as
(D 2 A κ,σ,x * ) (x,T ) (V, B), (V, B) = d 2 ds 2 s=0 A κ,σ,x * (x s , T s ),(11)
for (−ϵ, ϵ) ∋ s → (x s , T s ) ∈ O × IR + being any smooth map with (x 0 , T 0 ) = (x, T ) and ∂x s /∂s| s=0 = V and ∂T s /∂s| s=0 = B.
Since any two local primitives for η κ must differ by a constant, the bilinear form (D 2 A κ,σ,x * ) (x,T ) will not depend on the choices made, but only on the electromagnetic geodesic.We shall call it the energy-constrained index form of (x, T ) (or of γ), and shall denote it by Q κ,σ (x, T ), or Q κ,σ (γ).
Lemma 4.3.The energy-constrained index form of (x, T ) is given by
Q κ,σ (x, T ) (V 1 , B 1 ), (V 2 , B 2 ) = T 0 g(γ) D dt V1 , D dt V2 dt − T 0 g(γ) V1 , R( V2 , γ) γ − (∇ V2 Y )[ γ] − Y D dt V2 dt + B 2 T T 0 g(γ) V1 , Y [ γ] dt + B 1 T T 0 g(γ) V2 , Y [ γ] dt + 2κ 1 T B 1 B 2 .(12)
Proof.Let us compute the right-hand side of Eq. ( 11).To shorten notation, let T(s, t) = ẋs (t), S(s, t) = ∂x s (t)/∂s.Since dC σ = τ σ , then
d 2 ds 2 s=0 A κ,σ,x * (x s , T s ) = d 2 ds 2 s=0 A κ (x s , T s ) + d ds s=0 τ σ (x s ) [S] .
1− Recalling the definition of A κ and using that g(x)[ ẋ, ẋ] ≡ 2κT 2 , since g(γ)[ γ, γ] ≡ 2κ, the second derivative on the right-hand side above splits as
d 2 ds 2 s=0 A κ (x s , T s ) = 1 T d 2 ds 2 s=0 1 0 1 2 g(x s ) [T, T] dt − 2B T d ds s=0 1 0 1 2 g(x s )[T, T]dt + 2B 2 T κ
Now, by quite standard calculations, and using that
D ẋ/dt = T Y (x)[ ẋ], since D γ/dt = Y (γ)[ γ], d ds s=0 1 0 1 2 g(x s )[T, T]dt = −T 1 0 g(x) V, Y (x)[ ẋ] dt, d 2 ds 2 s=0 1 0 1 2 g(x s ) [T, T] dt = −T 1 0 g(x) D ds s=0 S , Y (x)[ ẋ] dt + 1 0 g(x) D dt V, D dt V dt − 1 0 g(x) [R(V, ẋ) ẋ, V ] dt 2− As for the derivative d/ds| s=0 τ σ (x s ) [S], one computes d ds s=0 τ σ (x s )[S] = 1 0 d ds s=0 g(x s ) S, Y (x s )[T] dt = 1 0 g(x) D ds s=0 S , Y (x)[ ẋ] dt + 1 0 g(x) V , (∇ V Y )[ ẋ] + Y (x) D dt V dt.
From the above computations one obtains that d 2 A κ,σ,x * /ds 2 | s=0 is equal to the rewrite in terms of x and V of the right-hand side of Eq. ( 12) for (V 1 , B 1 ) = (V 2 , B 2 ) = (V, B).The general expression in Eq. ( 12) is then obtained by a polarization argument.
4.5
The operators K(t) and D t .
The sum of the first two terms on the right-hand side of Eq. ( 12) can be rewritten in a more compact and symmetrical form, which is formally identical to the second variation of the standard geodesic action functional, via the introduction of operators K = K(t) : T γ(t) M → T γ(t) M and D t : X(γ) → X(γ), where X(γ) is the space of smooth vector fields along γ, defined by
Kv = R(v, γ) γ + 1 2 (∇ γ Y )[v] − (∇ v Y )[ γ] − 1 4 Y 2 [v], D t V = D dt V − 1 2 Y [ V ].
These operators can be obtained as the Jacobi operator and dynamical derivative, respectively, of P. Foulon [9] as applied to the Euler-Lagrange system of equations (1).Observe that D t is a first order linear differential operator which satisfies the Leibniz rule
D t (f V ) = f D t V + ḟ V , for f = f (t) a C 1 −function. Furthermore, we have
Lemma 4.4.The operators K and D t satisfy the following properties:
1. K is g−symmetric: g[K(t)u, v] = g[u, K(t)v], for all u, v ∈ T γ(t) M ;
2. D t is compatible with the metric:
(d/dt)g[ V , Ŵ ] = g[D t V , Ŵ ] + g[ V , D t Ŵ ], for all V , Ŵ ∈ X(γ).
Proof.The 2. follows at once from the metric compatibility of the connection and the fact that
Y is g−antisymmetric. Let us prove 1. Since v → R(v, γ) γ and Y 2 are g−symmetric, it suffices to show that v → S u [v] = (1/2)(∇ u Y )[v] − (∇ v Y )[u] is g−symmetric for all u.
On the one hand,
g S u [v], w − g v, S u [w] = 1 2 g (∇ u Y )[v], w − 1 2 g v, (∇ u Y )[w] −g (∇ v Y )[u], w + g v, (∇ w Y )[u] = g w, (∇ u Y )[v] + g u, (∇ v Y )[w] + g v, (∇ w Y )[u] ;
for the second equality we used that ∇ u Y is g−antisymmetric, which follows from the g−antisymmetry of Y .On the other hand, an easy computation shows that the exterior derivative of the 2−form σ
[• , • ] = g[ • , Y [•]] is given by dσ[u, v, w] = g u, (∇ v Y )[w] + g v, (∇ w Y )[u] + g w, (∇ u Y )[v] .(13)
Therefore, since dσ = 0 we conclude the g−symmetry of K.
It is straightforward to check that the sum of the first two terms on the right-hand side of Eq. ( 12) can be rewritten as the simpler expression employing D t and K,
T 0 g(γ) D t V1 , D t V2 dt − T 0 g(γ) V1 , K V2 dt.
The resulting expression for
Q κ,σ (x, T ) is thus Q κ,σ (x, T ) (V 1 , B 1 ), (V 2 , B 2 ) = T 0 g(γ) D t V1 , D t V2 dt − T 0 g(γ) V1 , K V2 dt + B 2 T T 0 g(γ) V1 , Y [ γ] dt + B 1 T T 0 g(γ) V2 , Y [ γ] dt + 2κ 1 T B 1 B 2 .(14)
Energy-constrained Jacobi fields
Until the end of this paper, let κ be a non null value of the energy and let γ : [0, T ] → M be an electromagnetic geodesic with energy κ connecting p to q.In the following we shall describe the kernel of the corresponding energy-constrained index form Q κ,σ (x, T ).
Let (V, B) be in the kernel of Q κ,σ (x, T ).In Proposition 7.2 it will be shown that V is smooth, so let us assume this.Thus, integrating by part the first term in the right-hand side of Eq. ( 12) and rearranging things, we obtain that
− T 0 g(γ) D 2 dt 2 V1 + R( V1 , γ) γ − (∇ V1 Y )[ γ] − Y D dt V1 − B 1 T Y [ γ] , V2 dt + B 2 T T 0 g(γ) V1 , Y [ γ] dt + 2κB 1 = 0 (15)
for all V 2 ∈ T x Ω p,q ([0, 1]) and all B 2 ∈ IR.It follows from the Fundamental Lemma of the Calculus of Variations that
D 2 dt 2 V1 + R( V1 , γ) γ − (∇ V1 Y )[ γ] − Y D dt V1 − B 1 T Y [ γ] = 0, B 1 = − 1 2κ T 0 g(γ) V1 , Y [ γ] dt.(16) (17)
Observe that, from Eq. ( 1), and since V1 vanishes on the end-points of [0, T ], we have that
T 0 g(γ) V1 , Y [ γ] dt = T 0 g(γ) V1 , D γ/dt dt = − T 0 g(γ) D V1 /dt, γ dt. (18)
Lemma 5.1.If a smooth vector field J along γ satisfies Eq. ( 16) for some B 1 ∈ IR, then g(γ) DJ/dt, γ is constant as a function of t.
Proof.Taking the g−inner product of both sides of Eq. ( 16) with γ,
g(γ) D 2 dt 2 J, γ + g(γ) R(J, γ) γ, γ − g(γ) (∇ J Y )[ γ], γ − g(γ) Y D dt J , γ − B 1 T g(γ) Y [ γ], γ = 0.
The second term on the left-hand side vanishes.Also, since Y is g−antissimetric the same is true of ∇ J Y , and therefore the third and fifth terms also vanish.Recalling that Y [ γ] = D γ/dt, we are left with
0 = g(γ) D 2 dt 2 J, γ − g(γ) Y D dt J , γ = g(γ) D 2 dt 2 J, γ + g(γ) D dt J, Y [ γ] = d dt g(γ) D dt J, γ ,
which was what we wanted to show.
Definition 5.2.An energy-constrained Jacobi field along an electromagnetic geodesic γ : [0, T ] → M with energy κ ̸ = 0 is a smooth vector field J along γ that satisfies the energy-constrained Jacobi equation
D 2 dt 2 J + R(J, γ) γ − (∇ J Y )[ γ] − Y D dt J − 1 2κ g(γ(0)) D dt J(0), γ(0) Y [ γ] = 0. (19)
We shall denote by J γ,κ the space of all energy-constrained Jacobi fields along γ.
It follows from Lemma 5.1 that the quantity g DJ/dt, γ is constant for J ∈ J γ,κ ; thus, Eq. ( 19) could have been written with g DJ/dt, γ | t=t0 in place of g DJ/dt, γ | t=0 for any given t 0 ∈ [0, T ].
In the absence of its last term, Eq. ( 19) becomes the well-known linearization of Eq. ( 1) along an electromagnetic geodesic.We shall refer to it as the ordinary Jacobi equation along γ, and accordingly we shall speak of ordinary Jacobi fields.
Example 5.3.The vector fields J tan 1 (t) = γ(t) and J tan 2 (t) = t γ(t) clearly solve the energy-constrained Jacobi equation.Reciprocally, any energy-constrained Jacobi field J that is everywhere tangent to γ is a linear combination of J tan 1 and J tan 2 .
From equations ( 16), ( 17), ( 18) and Lemma 5.1, we can state Proposition 5.4.The kernel of Q κ,σ (x, T ) is formed by the pairs (V, B) ∈ T x Ω p,q ([0, 1]) × IR such that J = V is an energy-constrained Jacobi field along γ and B = (T /2κ)g(γ) [DJ/dt, γ] | t=t0 , for any t 0 ∈ [0, T ].
It follows from this proposition that the bilinear form Q κ,σ (x, T ) is degenerate (in the sense of having non-trivial kernel) if, and only if, there exits a non null J ∈ J γ,κ that vanishes at both t = 0 and t = T .Definition 5.5.An instant t 0 ∈ (0, T ] for which there exists a non null J ∈ J γ,κ that vanishes at both t = 0 and t = t 0 shall be called an energy-constrained conjugate instant along γ.For such an instant t 0 , let J t0 be the space of all J ∈ J γ,κ that vanish at t = 0 and t = t 0 , and let J ′ [t 0 ] = {DJ/dt| t=t0 : J ∈ J t0 }.We shall say that t 0 is non-degenerate, if J ′ [t 0 ] is a non-degenerate subspace with respect to the symmetric bilinear form g t0 on T γ(t0) M defined by
g t0 u, v = g(γ(t 0 )) u, v − 1 2κ g(γ(t 0 )) γ(t 0 ), u g(γ(t 0 )) γ(t 0 ), v . (20)
The signature of a non-degenerate conjugate instant t 0 is defined as the signature of the restriction of g t0 to
J ′ [t 0 ].
Of course, we can define the form g t for an arbitrary t ∈ [0, T ].Observe that g t coincides with g(γ(t)) in the g−orthogonal complement γ(t)
⊥ and that it has a one-dimensional kernel generated by γ(t).
We shall also speak of ordinary conjugate instants along γ; these are defined by changing the term energy-constrained by ordinary in the above definition.
Energy-constrained versus ordinary Jacobi fields.
As proved in [11] with a different terminology, energy-constrained Jacobi fields along γ can also be obtained through one-parameter variations of (x, T ) through solutions of Eq. ( 1).More precisely, let (−ϵ, ϵ) ∋ s → (x s , T s ) be a smooth variation of (x, T ) such that γ s (t) = x s (t/T s ) is a solution of Eq. (1) for every s.If V (t) = dx s /ds| s=0 and B = dT s /ds| s=0 , then J(t) = V (t) is an energy-constrained Jacobi field along γ with g [DJ/dt, γ] ≡ 2κB/T .On the other hand, the variational vector field of the variation s → γ s must be an ordinary Jacobi field along γ.By a simple calculation, dγ s /ds| s=0 = J − (B/T )t γ.This way we obtain a correspondence between energy-constrained and ordinary Jacobi fields.This motivates the following: Lemma 5.6.Given a pair (J, B), where B ∈ IR and J is a solution to Eq. ( 16) with B in place of B 1 , an ordinary Jacobi field J along γ is obtained by setting J = J − (B/T )t γ.
Proof.The proof is a straightforward computation which we shall omit.
Symplectic property of energy-constrained Jacobi fields and conjugacy
There is a natural presymplectic structure that is preserved by the energy-constrained Jacobi equation.It is defined, for each t ∈ [0, T ], as the following antisymmetric bilinear form ωt on
T γ(t) M ⊕ T γ(t) M , ωt (u 1 , v 1 ), (u 2 , v 2 ) = g t v 1 , u 2 − g t u 1 , v 2 + σ(γ)[u 1 , u 2 ].
Lemma 6.1.The form ωt has a two-dimensional kernel generated by (0, γ) and ( γ, Y [ γ]).
Proof. Let (u 1 , v 1 ) ∈ ker ωt . From 0 = ωt [(u 1 , v 1 ), (0, v 2 )] = −g t [u 1 , v 2 ] for all v 2 , we obtain u 1 ∈ ker g t = ⟨ γ⟩. It follows that g[v 1 , γ] = g[v 1 − Y [u 1 ], γ], and hence 0 = ωt [(u 1 , v 1 ), (u 2 , 0)] = −g t [u 2 , Y [u 1 ] − v 1 ] for all u 2 . Therefore, Y [u 1 ] − v 1 ∈ ker g t = ⟨ γ⟩ Lemma 6.2.
The quantity ωt [(J 1 , DJ 1 /dt) , (J 2 , DJ 2 /dt)] remains constant along γ if J 1 and J 2 are two energy-constrained Jacobi fields.
Proof.Computing the derivative in t of ωt [(J 1 , DJ 1 /dt) , (J 2 , DJ 2 /dt)] and showing that it vanishes is quite standard.Besides Eq. ( 19), and the fact that g(γ) DJ i /dt, γ is constant, in the end one uses the relation (13).We shall omit the details.
Given vectors u, w ∈ T p=γ(0) M , let J u,w be the energy-constrained Jacobi field along γ such that J u,w (0) = u and DJ u,w /dt| t=0 = w.This sets up an isomorphism, for each t ∈ [0, T ],
Ψ t : T p M ⊕ T p M → T γ M ⊕ T γ M, Ψ t (u, w) = J u,w (t), D dt J u,w (t) . (21)
According to Lemma 6.
T p M ⊕ T p M ⟨(J tan 1 , DJ tan 1 /dt), (J tan 2 , DJ tan 2 /dt)⟩ | t=0 → T γ M ⊕ T γ M ⟨(J tan 1 , DJ t 1 /dt), (J tan 2 , DJ tan 2 /dt)⟩ . (22)
On the other hand, Lemma 6.1 shows that (J tan 1 , DJ tan 1 /dt) and (J tan 2 , DJ tan 2 /dt) span the kernel of ωt .Thus ωt descends to a symplectic form on the above quotient spaces which is, therefore, preserved by Ψt .Let us show that Ψt also recovers the notion of energy-constrained conjugacy.For this, let πt be the quotient map from T γ M ⊕ T γ M to the above quotient.Lemma 6.3.A given t 0 is an energy-constrained conjugate instant if, and only if, ( Ψt0 ) −1 πt0 ({0} ⊕ T γ M ) has non null intersection with π0 ({0} ⊕ T p M ).
Proof.It suffices to show that if J ∈ J γ,κ is tangent to γ at t = 0 and t = t 0 , then there exists a unique J ′ ∈ J γ,κ that vanishes at t = 0 and t = t 0 and such that J − J ′ is everywhere tangent to γ.But this is a direct consequence of the fact that the energy-constrained Jacobi fields everywhere tangent to γ are spanned by J tan 1 and J tan 2 .
We shall now show that up to a symplectic change of variables the map Ψt is nothing but the map Φt in (2).For this, recall that by means of the semi-Riemannian metric g one can construct a canonical identification
T (γ, γ) T M ∼ = T γ M ⊕ T γ M (23) relative to which the derivative Φ t = (Dζ t ) (p,v) of the Hamiltonian flow ζ t at (p, v) = (γ, γ)| t=0 is described by Φ t (u, w) = Ju,w , D Ju,w /dt | t ,
where Ju,w is defined analogously to J u,w by changing energy-constrained by ordinary.Moreover,
1. the canonical symplectic form ω of T M becomes ω(γ, γ) (u 1 , v 1 ), (u 2 , v 2 ) = g(γ)[v 1 , u 2 ] − g(γ)[u 1 , v 2 ] + σ(γ)[u 1 , u 2 ],(24)
2. the Hamiltonian vector field S is given by
S (γ, γ) = ( γ, Y [ γ]) = J tan 1 , DJ tan 1 /dt ,(25)
3. the tangent space to the energy surface E −1 (κ) is
T (γ, γ) E −1 (κ) = T γ M ⊕ ⟨ γ⟩ ⊥ . (26)
Also, the Lagrangian subspace L(γ, γ) in ( 3) is the image of {0} ⊕ ⟨ γ⟩ ⊥ under the quotient map π t :
T (γ, γ) E −1 (κ) → T (γ, γ) E −1 (κ)/⟨S⟩.
From (25) we have that the inclusion ι t :
T (γ, γ) E −1 (κ) → T γ M ⊕ T γ M descends to a map ῑt : T (γ, γ) E −1 (κ) S (γ, γ) → T γ M ⊕ T γ M ⟨(J tan 1 , DJ tan 1 /dt), (J tan 2 , DJ tan 2 /dt)⟩ .(27)
Lemma 6.4.The map ῑt is a symplectic isomorphism that relates Φt and Ψt , i.e., ῑt • Φt = Ψt • ῑ0 .
Proof.Since ordinary Jacobi fields J with D J/dt ⊥ γ are energy-constrained Jacobi fields, we see that
ι t • Φ t | TpM ⊕⟨v⟩ ⊥ = Ψ t • ι 0 . Therefore ῑt • Φt = Ψt • ῑ0
. Also, it is clear that ι t relates ωt with the pull-back of ω(γ) to T γ M ⊕ ⟨ γ⟩ ⊥ .To conclude, observe that the inverse of ῑt is the quotient of the map id ⊕ p t :
T γ M ⊕ T γ M → T γ M ⊕ ⟨ γ⟩ ⊥ , where p t : T γ M → ⟨ γ⟩ ⊥ is the g−orthogonal projection.
Let ℓ(t) be the Lagrangian path defined in (3).It follows from the lemma above and Lemma 6.3 that t 0 is an energy-constrained conjugate instant if, and only if, ℓ(t 0 ) ∩ L(p,v) ̸ = {0}.We shall show that the notions of non-degeneracy and signature for energy-constrained conjugacy match the corresponding ones for ℓ(t).For each t, consider the isomorphism
( Φt ) −1 • π t : {0} ⊕ ⟨ γ(t)⟩ ⊥ → ℓ(t).(28)
Lemma 6.5.Via the above isomorphism, the quadratic form l(t) corresponds to the restriction of g(γ(t))
to ⟨ γ(t)⟩ ⊥ . Proof. Let us fix a smooth frame E = (E 1 , ..., E n ) along γ with E n = γ and E i ∈ ⟨ γ⟩ ⊥ for i < n. A smooth frame A = A(t) for ℓ(t) is then obtained by projecting the (Φ t ) −1 (0, E i ) (i = 1, ..., n−1) to T (p,v) E −1 (κ)/⟨S⟩. Let A = A(t) be the 2n × n matrix whose columns are the coordinates of the (Φ t ) −1 (0, E i ) (i = 1, ..., n) in the frame for T γ M ⊕ T γ M
given by E ⊕ E. Let also ω = ω(t) be the matrix of ω(γ) in the frame E ⊕ E and G = G(t) be the matrix of g(γ) in the frame E. From (24) we obtain that
ω = P −G G O (for some matrix P = P (t)).(29)
It is clear that the matrix of l(t) in the frame A is the matrix ȦT ωA with the last row and last column removed.Thus all we have to show is that ȦT ωA = G.Let x = (x 1 , ..., x n ) T be the coordinates induced by E. In these coordinates, the ordinary Jacobi equation takes the form ẍ + Lx + N ẋ = 0 for some square matrices L = L(t) and N = N (t).Equivalently, we can write
ż = Hz, with H = O I n −L −N and z = x ẋ .
Let X = X(t) be the fundamental matrix solution of ż = Hz.
Then A = X −1 O I n , and thus Ȧ = −X −1 H O I n . Also, since (Φ t ) −1 leaves ω(γ) invariant, we have (X −1 ) T ωX −1 = ω. Therefore, from(29)
we obtain
ȦT ωA = − O I n H T (X −1 ) T ωX −1 O I n = − O I n H T ω O I n = G.
This completes the proof.Proposition 6.6.An energy-constrained conjugate instant t 0 is non-degenerate if, and only if, t 0 is a nondegenerate instant of intersection of ℓ(t) with the Maslov cycle Σ( L(p,v) ).Furthermore, for such an instant we have sig ℓ, L(p,v) , t 0 = sig g t0 | J ′ [t0] , and hence µ κ (γ,
t 0 ) = sig g t0 | J ′ [t0] .
Proof.Firstly, it is easily seen that J ′ [t 0 ] ∩ γ(t 0 ) = {0}, hence the g−orthogonal projection p t0 : T γ(t0) M → γ(t 0 ) ⊥ restricts to an injection J ′ [t 0 ] → γ(t 0 ) ⊥ .Since g t0 has kernel γ(t 0 ) and coincides with g(t 0 ) on γ(t 0 ) ⊥ , the injection p t0 | J ′ [t0] will be isometric if we endow J ′ [t 0 ] and γ(t 0 ) ⊥ with the restrictions of g t0 and g(t 0 ), respectively.Hence, if we show that ℓ(t 0 ) ∩ L(p,v) corresponds to p t0 (J ′ [t 0 ]) under the isomorphism (28), the result will follow from Lemma 6.5.For this, let πt and ῑt be as in Lemmas 6.3 and 6.4, respectively.Since ῑt sends L(γ, γ) onto πt ({0} ⊕ T γ M ) for each t, it follows from Lemma 6.4 that ῑ0 sends L(p,v) ∩ ℓ(t 0 ) onto π0 ({0} ⊕ T p M ) ∩ ( Ψt0 ) −1 πt0 ({0} ⊕ T γ M ).On the other hand, from the description of Ψ t in terms of energy-constrained Jacobi fields, and from Lemma 6.3, we see that the latter intersection is equal to ( Ψt0 ) −1 πt0 ({0} ⊕ J ′ [t 0 ]).It follows that ῑt0 sends Φt0 L(p,v) ∩ ℓ(t 0 ) onto πt0 ({0} ⊕ J ′ [t 0 ]).Therefore, since the inverse of ῑt0 is the quotient of the map id ⊕ p t0 :
T γ M ⊕ T γ M → T γ M ⊕ γ(t 0 ) ⊥ , we conclude that ℓ(t 0 ) ∩ L(p,v) corresponds to p t0 (J ′ [t 0 ]) under (28).
Another consequence of Lemma 6.5 is the following.Proposition 6.7.There exists ϵ > 0 such that there is no energy-constrained conjugate instant in (0, ϵ].
Proof.We have that ℓ(0) ∩ L(p,v) = L(p,v) ∼ = ⟨v⟩ ⊥ and l(0) is the restriction of g(p) to ⟨v⟩ ⊥ .Since κ ̸ = 0, that restriction is non-degenerate.Thus ℓ(t) has a non-degenerate intersection with Σ( L(p,v) ) at t = 0. Since such intersections are isolated, the result follows.
The energy-constrained spectral flow of an electromagnetic geodesic
In what follows we shall denote by H the space H 1 0 ([0, 1], IR n )×IR.On H we choose the Hilbert inner product
(v 1 , B 1 ), (v 2 , B 2 ) H = ⟨v 1 , v 2 ⟩ H 1 + B 1 B 2 = ⟨v 1 , v 2 ⟩ L 2 + ⟨ v1 , v2 ⟩ L 2 + B 1 B 2 .
By letting the endpoint q vary along γ and computing the energy-constrained index form of the corresponding electromagnetic geodesic, we obtain a one-parameter family of quadratic forms Q κ,σ (x s , s), s ∈ (0, T ], with varying domains, where x s : [0, 1] → M is the curve x s (t) = γ(st).We then bring this to a path {Q s } of quadratic forms on H as follows: fixed a smooth frame E 1 , ..., E n along γ, the correspon-
dence v = v(t) = (v 1 (t), ..., v n (t)) T → V s = V s (t) = i v i (t)E i (st)
is an isomorphism between H 1 0 ([0, 1], IR n ) and the tangent space T xs Ω p,γ(s) ([0, 1]).We then obtain an isomorphism, for each s ∈ (0, T ],
H ≃ −→ T xs Ω p,γ(s) ([0, 1]) × IR, (v, B) → (V s , sB).(30)
The quadratic forms {Q s } are then defined as the ones corresponding to the Q κ,σ (x s , s) via the above isomorphism,
Q s (v 1 , B 1 ), (v 2 , B 2 ) = Q κ,σ (x s , s) (V s 1 , sB 1 ), (V s 2 , sB 2 ) .(31)
Any two choices of frames will amount to paths {Q s } and {Q ′ s } that are isometric, i.e., the Q ′ s are of the form M * s Q s for some continuous (in fact smooth) path {M s } in GL(H).Thus {Q s } and {Q ′ s } will have essentially the same properties.In order to obtain a simple expression for the Q s we shall make the assumptions that the frame E 1 , ..., E n is both D t −parallel and g−orthonormal, i.e.,
D t E i = 0 and g(γ)[E i , E j ] = I n,p , for (I n,p ) ij = −1, if i = j ≤ p, 1, if i = j > p, 0, if i ̸ = j,(32)
where 0 ≤ p ≤ n is the index of the metric g; the existence of such a frame follows from D t being a first order linear differential operator which satisfies 2. of Lemma 4.4.With respect to this frame, let K = K(t) be product of I n,p with the matrix of K(t); ξ = ξ(t) be the product of I n,p with the column-vector of the coordinates of Y [ γ(t)]; K s (t) = s 2 K(st) and ξ s (t) = s 2 ξ(st).
Observe that since K is g−symmetric, then K T = K.Let also ⟨, ⟩ denote the standard scalar product of IR n .Lemma 7.1.The quadratic forms Q s are given by
Q s (v 1 , B 1 ), (v 2 , B 2 ) = 1 s 1 0 ⟨I n,p v1 , v2 ⟩dt − 1 s 1 0 ⟨K s v 1 , v 2 ⟩dt + B 1 1 s 1 0 ⟨v 2 , ξ s ⟩dt + B 2 1 s 1 0 ⟨v 1 , ξ s ⟩dt + 2κsB 1 B 2 . (33)
In particular, {Q s } is a smooth path.
Proof.The right-hand side of (31) was already computed in Eq. ( 14) once one replaces T by s and B i by sB i in the latter.To show that it matches (33), observe first that if
V (t) = i v i (t)E i (st), then V (t) = i v i (t/s)E i (t)
, and then use that E 1 , ..., E n is an orthonormal D t −parallel frame and that D t satisfies the Leibniz rule; we leave the details to the reader.
Proposition 7.2. The forms Q s are of Fredholm type. Also, if (v, B) is in the kernel of Q s then v is smooth. Proof. Let −d 2 /dt 2 : H 2 ([0, 1], IR n ) ∩ H 1 0 ([0, 1], IR n ) ⊂ L 2 ([0, 1], IR n ) → L 2 ([0, 1], IR n ) be the Dirichlet Lapla- cian. It is well-known that 1 − d 2 /dt 2 has a bounded inverse (1 − d 2 /dt 2 ) −1 : L 2 → H 2 ∩ H 1 0 and it is clear that v 1 , v 2 L 2 = (1 − d 2 /dt 2 ) −1 v 1 , v 2 H 1 , if v 1 ∈ L 2 , v 2 ∈ H 1 0 .
Thus we can write, for v 1 and v 2 in H 1 0 ,
1 s 1 0 ⟨I n,p v1 , v2 ⟩dt − 1 s 1 0 ⟨K s v 1 , v 2 ⟩dt = 1 s I n,p v 1 , v 2 H 1 − 1 s I n,p v 1 , v 2 L 2 − 1 s K s v 1 , v 2 L 2 = 1 s I n,p v 1 , v 2 H 1 − 1 s (1 − d 2 /dt 2 ) −1 I n,p v 1 , v 2 H 1 − 1 s (1 − d 2 /dt 2 ) −1 K s v 1 , v 2 H 1
and
B 1 1 s 1 0 ⟨v 2 , ξ s ⟩dt + B 2 1 s 1 0 ⟨v 1 , ξ s ⟩dt + 2κsB 1 B 2 = 1 s B 1 ξ s , v 2 L 2 + 1 s v 1 , ξ s L 2 + 2κsB 1 B 2 = 1 s B 1 (1 − d 2 /dt 2 ) −1 ξ s , v 2 H 1 + 1 s v 1 , ξ s L 2 + 2κsB 1 B 2 .
Therefore
Q s (v 1 , B 1 ), (v 2 , B 2 ) = 1 s I n,p v 1 − (1 − d 2 /dt 2 ) −1 (I n,p v 1 + K s v 1 − B 1 ξ s ) , v 2 H 1 + 1 s v 1 , ξ s L 2 + 2κsB 1 B 2 ,(34)
from where it follows that the self-adjoint operator L s which represents Q s is given by L s = I − K, with
I(v, B) = 1 s I n,p v , 2κsB , K(v, B) = 1 s (1 − d 2 /dt 2 ) −1 (I n,p + K s )v , 0 − 1 s Bξ s , v, ξ s L 2
and ξ s = (1 − d 2 /dt 2 ) −1 ξ s .It is clear that I is an isomorphism of H.As for K, it is a compact operator, since the operator (1 − d 2 /dt 2 ) −1 (I n,p + K s ) : H 1 0 → H 1 0 factors through the compact injection H 1 0 → L 2 , and the operator H → H, (v, B) → Bξ s , ⟨v, ξ s ⟩ L 2 has rank one.Hence L s is Fredholm.
If (v, B) is in the kernel of L s , then v = I n,p (1 − d 2 /dt 2 ) −1 (I n,p + K s )v − BI n,p ξ s .
This, together with the fact that (1 − d 2 /dt 2 ) −1 maps H l into H l+2 for each l = 1, 2, ..., shows that v is smooth.
The degenerate instants for Q = {Q s } are the energy-constrained conjugate instants along γ and, according to Proposition 6.7, there is no such instant in (0, ϵ] for ϵ sufficiently small.Therefore we can define Definition 7.3.Suppose that T is not an energy-constrained conjugate instant along γ.The energyconstrained spectral flow of γ, sf κ (γ), is defined as sf κ (γ) = sf(Q, [ϵ, T ]) for ϵ > 0 sufficiently small.
As already observed, a change of frame used to define Q = {Q s } will produce a path Q ′ = {Q ′ s } that is isometric to the former; in terms of the self-adjoint representations L = {L s } and L ′ = {L ′ s } of Q and Q ′ , this means that L and L ′ are cogredient.Since the spectral flow is invariant under cogredience, it follows that the above definition does not depend on the choices made.
Proofs of the main results
Throughout we shall suppose that T is neither an energy-constrained nor an ordinary conjugate instant along γ, as well as ϵ > 0 is such that there is no such instants in (0, ϵ].We shall continue to assume the setting in Sec. 7.
Computing the difference of spectral flows.
Let V ⊂ H be the subspace V = H 1 0 ([0, 1], IR n ) × {0}, and let Q = {Q s } be the restrictions of Q s to V; the form Q s corresponds to the usual index form of the electromagnetic geodesic γ| [0,s] .As is well-known, degenerate instants for {Q s } are the ordinary conjugate instants along γ.The spectral flow sf(Q, [ϵ, T ]) shall be called the ordinary spectral flow of γ and denoted by sf(γ).
The first step in the proof of Theorem 1.4 is to compute the difference sf κ (γ) − sf(γ).According to Proposition 3.4, we have sf
κ (γ) − sf(γ) = ind Q ϵ V ⊥ Qϵ − ind Q T V ⊥ Q T .(35)
So let us compute the above indices.First, observe that
Lemma 8.1. Given s ∈ (0, T ], if (v, B) ∈ V ⊥ Qs then v is smooth.
Proof.The proof is identical to the proof we gave for the case (v, B) ∈ ker Q s in Proposition 7.2.
Proposition 8.2.Let s = ϵ, T .There is a unique ordinary Jacobi field J * s along γ such that J * s (0) = 0 and J * s (s) = γ(s).In terms of J * s , we have
ind Q s V ⊥ Qs = 1, if g(γ) D J * s /dt, γ t=s < 0, 0, if g(γ) D J * s /dt, γ t=s ≥ 0.
Proof.Let us suppose s = T , the case s = ϵ being analogous.The existence and uniqueness of such J * T follows at once from the assumption that T is not an ordinary conjugate instant along γ.Also, since V is one-codimensional and H = V ⊕ V ⊥ Q T (Lemma 3.3), it follows that dim V ⊥ Q T = 1.In order to describe Q T V ⊥ Q T , we shall work directly with Q κ,σ (x, T ) instead of Q T .So let us take a non null (V, B) in the Q κ,σ (x, T )−orthogonal complement of T x Ω p,q ([0, 1]) × {0}.From the above lemma, V is smooth.By making B 2 = 0 in Eq. ( 15), we see that J = V is a solution to Eq. ( 16) with B in place of B 1 .By making (V 1 , B 1 ) = (V 2 , B 2 ) = (V, B) in the left-hand side of Eq. ( 15), we thus obtain
Q κ,σ (x, T )[(V, B), (V, B)] = B T T 0 g(γ) J, Y [ γ] dt + 2κB .
Integrating by parts as in (18) and using Lemma 5.1, we arrive at
Q κ,σ (x, T )[(V, B), (V, B)] = −Bg(γ) [DJ/dt, γ] t=T + (2κ/T )B 2 .(36)
Now, according to Lemma 5.6, J = J − (B/T )t γ is an ordinary Jacobi field.Rewriting the right-hand side of (36) in terms of J, we obtain
Q κ,σ (x, T )[(V, B), (V, B)] = 1 2κ g(γ) J, γ g(γ) D J/dt, γ t=T ,(37)
since J(T ) = −B γ(T ) (recall that J(T ) = 0).Since the pair (V, B) is non null, and T is not an ordinary conjugate instant, we must have B ̸ = 0, otherwise J would be a non null ordinary Jacobi field vanishing at t = 0 and t = T .Thus, by dividing by −B, we could have taken (V, B) with B = −1, in which case J = J * T and the right-hand side of (37) would be g(γ) D J * T /dt, γ t=T .This concludes the proof.
8.2
The Lagrangian path ℓ(t) as a symplectic reduction.
As in Sec.??, let Φ t be the derivative at (p, v) of the Hamiltonian flow ζ t .The vertical distribution V T M on T M , given by the tangent spaces to the fibers of T M → M , is Lagrangian.By pulling it back by Φ t , we obtain a Lagrangian path
ľ : [0, T ] → Λ T (p,v) T M , ľ(t) = (Φ t ) −1 V (γ, γ) T M.
The previously defined Lagrangian path ℓ(t) is nothing but the symplectic reduction of ľ(t) by the coisotropic subspace T (p,v) E −1 (κ) ⊂ T (p,v) T M in the sense of [19].Indeed, ⟨S⟩ is the symplectic-orthogonal complement of T E −1 (κ) and we have V E −1 (κ) = V T M ∩ T E −1 (κ), so that the Lagrangian subbundle L of T E −1 (κ)/⟨S⟩ is the symplectic reduction of the Lagrangian distribution L along E −1 (κ) given by
L = ⟨S⟩ + V T M ∩ T E −1 (κ).
It is clear that ľ(t) ∩ ⟨S (p,v) ⟩ = {0} for all t since S is never vertical and Φ t (S (p,v) ) = S (γ, γ) .Therefore, we can apply Theorem 2.3 of [19] to conclude:
Proposition 8.3.The energy-constrained Maslov index µ κ (γ) is equal to the Maslov index of ľ| [ϵ,T ] with respect to the reference Lagrangian L (p,v) .
Computation of Kashiwara indices.
Intersections of the Lagrangian path ľ(t) with the Maslov cycle Σ V (p,v) T M correspond to ordinary conjugate instants along γ; this follows from the description of Φ t in terms of ordinary Jacobi fields.We shall call the Maslov index of ľ| [ϵ,T ] with respect to the reference Lagrangian V (p,v) T M the ordinary Maslov index of γ and denote it by µ(γ).
According to Eq. ( 6), the difference of the Maslov indices of ľ| [ϵ,T ] with respect to the reference Lagrangians L (p,v) and V (p,v) T M , respectively, can be computed as half the difference of Kashiwara indices.Together with Proposition 8.3, this gives us
µ κ (γ) − µ(γ) = 1 2 τ L (p,v) , V (p,v) T M, ľ(T ) − 1 2 τ L (p,v) , V (p,v) T M, ľ(ϵ) . (38)
For the rest of this section, let s = ϵ, T .Also, we shall omit the s in γ(s) and γ(s).
Since the Kashiwara index is invariant by symplectic transformations, by applying Φ s we obtain that τ L (p,v) , V (p,v) T M, ľ(s) = τ Φ s L (p,v) , Φ s V (p,v) T M, V (γ, γ) T M .Let us denote the Lagrangian triplet on the right-hand side by (L 1 , L 2 , L 3 ).For the following, have in mind the identification (23).Since s is not an ordinary conjugate instant along γ, L 2 has null intersection with V (γ, γ) T M = {0} ⊕ T γ M .Therefore there exists a linear map A s :
T γ M → T γ M such that L 2 = (u, A s u) : u ∈ T γ M . Lemma 8.4. The adjoint A * s of A s with respect to g(γ) is equal to A s − Y .
Proof.On one hand, for all u 1 , u 2 ∈ T γ M we have
ω(γ) (u 1 , A s u 1 ), (u 2 , A s u 2 ) = g(γ) A s u 1 , u 2 − g(γ) u 1 , A s u 2 + g(γ) u 1 , Y [u 2 ] = g(γ) u 1 , A * s u 2 − A s u 2 + Y [u 2 ] .
On the other hand, since L 2 is Lagrangian, the above must be zero.
Lemma 8.5.We have
A s γ − Y [ γ] ̸ = 0 and the Lagrangian subspace L 1 ⊂ T γ M ⊕ T γ M is given by L 1 = ( γ, Y [ γ]) + (u, A s u) : u ∈ A s γ − Y [ γ] ⊥ .
Proof.Applying Φ s to the equality
L (p,v) = ⟨S (p,v) ⟩+{0}⊕⟨v⟩ ⊥ we obtain L 1 = Φ s L (p,v) = ⟨S (γ, γ) ⟩+Φ s ({0}⊕ ⟨v⟩ ⊥ ). We have S (γ, γ) = ( γ, Y [ γ]) and, since Φ s (T p M ⊕⟨v⟩ ⊥ ) = T γ M ⊕⟨ γ⟩ ⊥ , the subspace Φ s ({0}⊕⟨v⟩ ⊥ ) is the intersection of L 2 with T γ M ⊕ ⟨ γ⟩ ⊥ , which in turn is given by (u, A s u) : u ∈ T γ M and g(γ)[A s u, γ] = 0 . By the Lemma 8.4, the equation g(γ)[A s u, γ] = 0 is the same as g(γ)[u, A s γ − Y [ γ]] = 0. If we had A s γ − Y [ γ] = 0, then L 1 would have dimension n + 1, an absurd.
We have therefore an isomorphism
IR ⊕ A s γ − Y [ γ] ⊥ ⊕ T γ M ⊕ T γ M ≃ −→ L 1 ⊕ L 2 ⊕ L 3 , (λ, u 1 , u 2 , u 3 ) → λ( γ, Y [ γ]) + x 1 , x 2 , x 3 ,
where x i = (u i , A s u i ), for i = 1, 2, and x 3 = (0, u 3 ).As in Sec.2.1, let Q be the quadratic form corresponding to the Lagrangian triplet (L 1 , L 2 , L 3 ) and denote by Q the pull-back of Q by the above isomorphism.We shall describe Q.
For i = 1, 2, 3, let u i , v i ∈ T γ M , with u 1 , v 1 ∈ ⟨A s γ − Y [ γ]⟩ ⊥ .
Using that ω(γ) vanishes on L 2 , and that
ω(γ) ( γ, Y [ γ]), (w, A s w) = g(γ) Y [ γ], w − g(γ) γ, A s w + g(γ) γ, Y [w] = −g(γ) w, A s γ − Y [ γ] ∀w ∈ T γ M, a direct computation yields 2 Q (λ 1 , u 1 , u 2 , u 3 ), (λ 2 , v 1 , v 2 , v 3 ) = −λ 1 g(γ) v 2 , A s γ − Y [ γ] − g(γ)[v 3 , γ] − λ 2 g(γ) u 2 , A s γ − Y [ γ] − g(γ)[u 3 , γ] − (g(γ)[u 2 , v 3 ] + g(γ)[v 2 , u 3 ]) + g(γ)[u 3 , v 1 ] + g(γ)[v 3 , u 1 ].(39)
In order to introduce convenient coordinates to describe the matrix of Q, it is useful to distinguish between the following three cases, 1)
g(γ) A s γ − Y [ γ] , A s γ − Y [ γ] < 0, 2) g(γ) A s γ − Y [ γ] , A s γ − Y [ γ] > 0, 3) g(γ) A s γ − Y [ γ] , A s γ − Y [ γ] = 0.(40)
Suppose, for instance, that we are in the third case above.In this case, we can introduce a g−orthonormal basis e 1 , ..., e n on T γ M such that
A s γ − Y [ γ] = λ(e 1 + e n ), for some λ ̸ = 0.
Recall that by g−orthonormal we mean that (g(γ)[e i , e j ]) is the matrix I n,p introduced in (32).A basis for
A s γ − Y [ γ]
⊥ is then e 1 + e n , e 2 , ..., e n−1 .We equip the space IR ⊕ A s γ − Y [ γ] ⊥ ⊕ T γ M ⊕ T γ M with the direct sum of the bases at hand.Also, let a 1 , ..., a n be such that γ = n i=1 a i e i .From (39) it follows that the matrix of 2 Q in that basis is
Υ = 0 0 0 ••• 0 0 0 λ 0 ••• 0 0 −λ −a 1 ••• −ap a p+1 ••• an 0 0 0 ••• 0 0 0 0 0 ••• 0 0 0 −1 0 0 ••• 0 1 0 0 0 ••• 0 0 0 0 0 ••• 0 0 0 0 −1 0 ••• 0 0 ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• 0 0 0 ••• 0 0 0 0 0 ••• 0 0 0 0 0 0 ••• 1 0 λ 0 0 ••• 0 0 0 0 0 ••• 0 0 0 1 0 0 ••• 0 0 0 0 0 ••• 0 0 0 0 0 ••• 0 0 0 0 1 0 ••• 0 0 0 0 0 ••• 0 0 0 0 0 ••• 0 0 0 0 0 1 ••• 0 0 ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• 0 0 0 ••• 0 0 0 0 0 ••• 0 0 0 0 0 0 ••• −1 0 −λ 0 0 ••• 0 0 0 0 0 ••• 0 0 0 0 0 0 ••• 0 −1 −a 1 −1 0 ••• 0 0 0 1 0 ••• 0 0 0 0 0 0 ••• 0 0 ••• 0 −1 ••• 0 0 0 0 1 ••• 0 0 0 0 0 0 ••• 0 0 −ap ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• ••• a p+1 0 0 ••• 1 0 0 0 0 ••• −1 0 0 0 0 0 ••• 0 0 ••• 0 0 ••• 0 1 0 0 0 ••• 0 −1 0 0 0 0 ••• 0 0 an 1 0 ••• 0 0 0 0 0 ••• 0 0 −1 0 0 0 ••• 0 0
, where:
-the red blocks are equal to −I n,p , -the upper blue block is (n − 1) × n and has a diagonal formed by p minus ones followed by n − p − 1 plus ones, -the bottom blue block is the transpose of the upper one.
By performing a few elementary cogredient transformations (i.e., a sequence of row operations followed by the same operations on the columns) on Υ we arrive at the matrix Observe first that since the difference of Maslov indices µ κ (γ) − µ(γ) is an integer, the right-hand side of (38) must be an integer.Thus, Proposition 8.6 implies that if g(γ) D J * s /dt, γ t=s is zero for one s ∈ {ϵ, T }, then it is also zero for the other s.Therefore, by comparing (35) and Proposition 8.2 with (38) and Proposition 8.6, we obtain sf κ (γ) − sf(γ) = µ(γ) − µ κ (γ).
Υ ′ = 2λ(a 1 − a n ) O (n
The proof of Theorem 1.4 is thus reduced to the proof of the equality sf(γ) = −µ(γ), which in turn is the usual Morse index theorem proved in Proposition 2.5 of [16].
8.5 Proof of Theorem 1.5 and Corollary 1.6.
Theorem 1.5 will follow from Theorem 3.6 and Theorem 1.4 once we frame our bifurcation problem within the abstract setting of Sec.3.3.In order to do so, recall that, for each s ∈ (0, T ], x s : [0, 1] → M is the curve x s (t) = γ(st).We have thus a one-parameter family of local magnetic κ−action functionals centered at x s , A κ,σ,xs : O s × IR + ⊂ Ω p,γ(s) ([0, 1]) × IR + → IR, s ∈ (0, T ],
each of which possessing (x s , s) as a critical point.By means of the parametrizations ( 9) and the fixed frame E 1 , ..., E n along γ, we can identify {A κ,σ,xs } with a smooth family of functionals with s−independent domains, F s : H 1 0 ([0, 1], B n ρ ) × IR + → IR, s ∈ (0, T ], all of which having (0, 1) as the critical point corresponding to (x s , s).More precisely: for each s ∈ (0, T ], we use the frame E s 1 , ..., E s n along x s given by E s i (t) = E i (st) to define the map ψ s : [0, 1] × B n ρ → M as in (8) with x * replaced by x s .Observe that ψ s (t, x) = ψ T ((s/T )t, x) and, hence, (s, t, x) → ψ s (t, x) is smooth.If we choose ρ so that ψ T (t, •) : B n ρ → M is a diffeomorphism onto an open set for each t, the same will be true of the maps ψ s (t, •) : B n ρ → M for all s and t.Let then Ψ s : H 1 0 ([0, 1], B n ρ ) → Ω p,γ(s) ([0, 1]) be the parametrization around x s corresponding to ψ s as in (9).The desired family {F s } s∈(0,T ] is then defined by F s (x, r) = A κ,σ,xs (Ψ s (x), sr).
For the smoothness of (s, x, r) → F s (x, r), let us split A κ,σ,xs as A s κ + C σ,xs , for A s κ : Ω p,γ(s) ([0, 1]) × IR + → IR the κ−action functional of the semi-Riemannian Lagrangian.The smoothness of (s, x, r) → A s κ (Ψ s (x), sr) follows easily from that of (s, t, x) → ψ s (t, x).Furthermore, The claimed smoothness follows now from the smoothness of (s, t, x) → (h * s θ)(t, x).
Each functional F s has (0, 1) as a critical point since Ψ s (0) = x s .Also, since the derivative of the diffeomorphism (x, r) → (Ψ s (x), sr) at (0, 1) is the isomorphism (30), the second derivative (D 2 F s ) (0,1) is equal to the quadratic form Q s of Sec. 7. On the other hand, it is clear that an instant t 0 is an energyconstrained bifurcation instant along γ if, and only if, it is a bifurcation instant for the family {F s } s∈(0,T ]
Theorem 3 . 6 .
36
In the above setting, suppose that the endpoints Q a and Q b are non-degenerate.If sf(Q, [a, b]) ̸ = 0, then there exists a bifurcation instant in (a, b) for the family {F s }.
1 ,− 1 , 1 ,
111
−1)×(n−1) O n×n −I n,p −I n,p O n×n , where O k×k is a k × k matrix of zeros and the omitted elements are zeros.The 2n × 2n bottom-right block of Υ ′ has null signature.Also, it follows from A s γ − Y [ γ] = λ(e 1 + e n ), and from the g−antisymmetryof Y , that 2λ(a 1 − a n ) = −2g(γ)[A s γ, γ].Therefore, sig Q = sig Q = sig Υ ′ = if g(γ)[A s γ, γ] < 0, if g(γ)[A s γ, γ] > 0, 0, if g(γ)[A s γ, γ] = 0.The cases 1) and 2) in (40) can be treated quite similarly and provide the same value for sig Q as above.Let now J * s be as in Proposition 8.2.Since L 2 = Φ s V (p,v) T M consists of all pairs ( J, D J/dt)| t=s where J is an ordinary Jacobi field vanishing at t = 0, then A s γ = D J * s /dt| t=s .In conclusion, we have Proposition 8.6.Let s = ϵ, T , and let J * s be as in Proposition 8.2.Then,τ L (p,v) , V (p,v) T M, ľ(s) = if g(γ) D J * s /dt, γ t=s < 0, −1, if g(γ) D J *s /dt, γ t=s > 0, 0, if g(γ) D J * s /dt, γ t=s = 0.
8. 4
4
Proof of Theorem 1.4.
Lemma 8 . 7 . 1 0 1 0
8711
The map (s, x) → C κ,xs (Ψ s (x)) is smooth.Proof.As in the discussion following Corollary 4.2, let θ be a 1−form on[0, 1] × B n ρ such that ψ * T σ = dθ.For each s, let h s : [0, 1] × B n ρ → [0, 1] × B n ρ be the diffeomorphism h s (t, x) = ((s/T )t, x).Since ψ s = ψ T • h s , we have that ψ * s σ = d(h * s θ).Thus, according to Eq. (10),C σ,xs (Ψ s (x)) = (h * s θ)(t, x)[(1, ẋ)]dt − (h * s θ)(t, 0)[(1, 0)]dt.
2, the above isomorphism preserves the presymplectic form ωt .It is clear that t is an energy-constrained conjugate instant if, and only if, (Ψ t ) −1 ({0} ⊕ T γ M ) has non null intersection with {0} ⊕ T p M .Let J tan
1and J tan 2be as in Example 5.3. Then Ψ t descends to an isomorphism between quotientspaces,Ψt :
in the sense of Sec.3.3; in particular, such an instant must be a degenerate instant for {Q s } and thus an energy-constrained conjugate instant along γ.Theorem 1.5 follows now from Theorem 3.6 and Theorem 1.4.As for the proof of Corollary 1.6, observe that Theorem 1.5 together with the additivity under concatenation of both the Maslov index and the spectral flow imply the equality sf(Q, t 0 ) = −µ κ (γ, t 0 ).We now apply Corollary 3.7 to obtain the result.Fernandes, Cidade Universitária, 50740560, Recife, PE, Brasil.E-mail address: henrique.vitori@ufpe.br
Lectures on the free period Lagrangian action functional. A Abbondandolo, J. Fixed Point Theory Appl. 1322013
The Lusternik-Fet theorem for autonomous Tonelli Hamiltonian systems on twisted cotangent bundles. L Asselle, G Benedetti, J. Topol. Anal. 832016
Magnetic curvature and existence of closed magnetic geodesics on low energy levels. V Assenza, arXiv:2309.031592023
Spectral asymmetry and Riemannian geometry. M Atiyah, V Patodi, I Singer, III. Math. Proc. Camb. Philos. Soc. 791976
On a formula for the spectral flow and its applications. P Benevieri, P Piccione, Math. Nachr. 28352010
Instability and bifurcation. R Bettiol, P Piccione, Notices Amer. MAth. Soc. 67112020
On the Maslov index. S E Cappell, R Lee, E Y Miller, Commun. Pure Appl. Math. 4721994
Spectral flow and bifurcation of critical points of strongly-indefinite functionals. I. General theory. P M Fitzpatrick, J Pejsachowicz, L Recht, J. Funct. Anal. 16211999
Géométrie des équations différentielles du second ordre. P Foulon, Ann. Inst. H. Poincaré Phys. Théor. 4511986
Gravitational lensing in general relativity via bifurcation theory. R Giambò, F Giannoni, P Piccione, Nonlinearity. 1712004
A second-order variational principle for the Lorentz force equation: conjugacy and bifurcation. R Giambò, M A Javaloyes, Proc. Roy. Soc. Edinburgh Sect. A. 13752007
Computation of the Maslov index and the spectral flow via partial signatures. R Giambò, P Piccione, A Portaluri, C. R. Math. Acad. Sci. 33852004
The Weil Representation, Maslov Index and Theta Series. G Lions, M Vergne, Progr. Math. Birkhäuser. 1980
Morse index and bifurcation of p-geodesics on semi Riemannian manifolds. M Musso, J Pejsachowicz, A Portaluri, ESAIM Control Optim. Calc. Var. 1332007
Self-adjoint Fredholm operators and spectral flow. J Phillips, Can. Math. Bull. 3941996
A bifurcation result for semi-Riemannian trajectories of the Lorentz force equation. P Piccione, A Portaluri, J. Differential Equations. 21022005
Spectral flow, Maslov index and bifurcation of semi-Riemannian geodesics. P Piccione, A Portaluri, D V Tausk, Ann. Global Anal. Geom. 2522004
A student's guide to symplectic spaces, Grassmannians and Maslov index. P Piccione, D V Tausk, Rio de Janeiro: Instituto Nacional de Matemática Pura e Aplicada (IMPA). 2008
On the Maslov index in a symplectic reduction and applications. H Vitório, Proc. Am. Math. Soc. 14882020
| [
-0.16143029928207397,
-0.023018021136522293,
0.22995957732200623,
0.05446859821677208,
0.005068199709057808,
0.06036749482154846,
0.15485414862632751,
-0.0074682896956801414,
0.013962752185761929,
-0.11663012206554413,
0.051399558782577515,
0.02437223121523857,
-0.056633833795785904,
-0.08... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.