101 research outputs found
Out-of-equilibrium dynamical equations of infinite-dimensional particle systems. II. The anisotropic case under shear strain
No full textAs an extension of the isotropic setting presented in the companion paper Agoritsas et al (2019 J. Phys. A: Math. Theor. 52 144002), we consider the Langevin dynamics of a many-body system of pairwise interacting particles in d dimensions, submitted to an external shear strain. We show that the anisotropy introduced by the shear strain can be simply addressed by moving into the co-shearing frame, leading to simple dynamical mean field equations in the limit d -> infinity. The dynamics is then controlled by a single one-dimensional effective stochastic process which depends on three distinct strain-dependent kernels-self-consistently determined by the process itself-encoding the effective restoring force, friction and noise terms due to the particle interactions. From there one can compute dynamical observables such as particle mean-square displacements and shear stress fluctuations, and eventually aim at providing an exact d -> infinity benchmark for liquid and glass rheology. As an application of our results, we derive dynamically the 'statefollowing' equations that describe the static response of a glass to a finite shear strain until it yields
Out-of-equilibrium dynamical equations of infinite-dimensional particle systems I. The isotropic case
No full textWe consider the Langevin dynamics of a many-body system of interacting particles in d dimensions, in a very general setting suitable to model several out-of-equilibrium situations, such as liquid and glass rheology, active self-propelled particles, and glassy aging dynamics. The pair interaction potential is generic, and can be chosen to model colloids, atomic liquids, and granular materials. In the limit d -> infinity, we show that the dynamics can be exactly reduced to a single one-dimensional effective stochastic equation, with an effective thermal bath described by kernels that have to be determined self-consistently. We present two complementary derivations, via a dynamical cavity method and via a path-integral approach. From the effective stochastic equation, one can compute dynamical observables such as pressure, shear stress, particle mean-square displacement, and the associated response function. As an application of our results, we derive dynamically the 'state-following' equations that describe the response of a glass to quasistatic perturbations, thus bypassing the use of replicas. The article is written in a modular way, that allows the reader to skip the details of the derivations and focus on the physical setting and the main results
Performance of logistic regression modeling: beyond the number of events per variable, the role of data structure
No full textReply to : Steyerberg EW, Schemper M, Harrell FE. Logistic regression modeling and the number of events per variable: selection bias dominates. J Clin Epidemiol. 2011 Dec;64(12):1464-5; author reply 1463-4. doi: 10.1016/j.jclinepi.2011.06.016. PMID: 22032755. which is a comment on : Courvoisier DS, Combescure C, Agoritsas T, Gayet-Ageron A, Perneger TV. Performance of logistic regression modeling: beyond the number of events per variable, the role of data structure. J Clin Epidemiol. 2011 Sep;64(9):993-1000. doi: 10.1016/j.jclinepi.2010.11.012. Epub 2011 Mar 16. PMID: 21411281. https://archive-ouverte.unige.ch/unige:25409</a
Including practical issues and patient perspectives in Rapid Recommendations
No full textComment on : Siemieniuk RA, Agoritsas T, Macdonald H, Guyatt GH, Brandt L, Vandvik PO. Introduction to BMJ Rapid Recommendations. BMJ. 2016 Sep 28;354:i5191. doi: 10.1136/bmj.i5191. PMID: 27680768. https://archive-ouverte.unige.ch/unige:90417</a
Adjustment Strategies in Studies of Therapy—Reply
No full textComment in reply to Karp I. Adjustment Strategies in Studies of Therapy. JAMA. 2017 Jun 6;317(21):2238-2239. doi: 10.1001/jama.2017.4880. PMID: 28586883. This was already a comment on the author's previous publication: Agoritsas T, Merglen A, Shah ND, O'Donnell M, Guyatt GH. Adjusted Analyses in Studies Addressing Therapy and Harm: Users' Guides to the Medical Literature. JAMA. 2017 Feb 21;317(7):748-759. doi: 10.1001/jama.2016.20029. PMID: 28241362. which is available in Archive ouverte under https://archive-ouverte.unige.ch/unige:108131</a
Multiscaling analysis of ferroelectric domain wall roughness
No full textUsing multiscaling analysis, we compare the characteristic roughening of ferroelectric domain walls in Pb(Zr0.2Ti0.8)O3 thin films with numerical simulations of weakly pinned one-dimensional interfaces. Although at length scales up to LMA ≥ 5 μm the ferroelectric domain walls behave similarly to the numerical interfaces, showing a simple monoaffine scaling (with a well-defined roughness exponent ζ), we demonstrate more complex scaling at higher length scales, making the walls globally multiaffine (varying ζ at different observation length scales). The dominant contributions to this multiaffine scaling appear to be very localized variations in the disorder potential, possibly related to dislocation defects present in the substrate.Fil: Guyonnet, J.. Universidad de Ginebra; SuizaFil: Agoritsas, E.. Universidad de Ginebra; SuizaFil: Bustingorry, Sebastian. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Giamarchi, T.. Universidad de Ginebra; SuizaFil: Paruch, P.. Universidad de Ginebra; Suiz
Post-test Probability According to Prevalence
No full textReply to : Galen BT. Post-test probability according to prevalence. J Gen Intern Med. 2011 Oct;26(10):1090. doi: 10.1007/s11606-011-1787-5. PMID: 21751056; PMCID: PMC3181292 which is a comment on : Agoritsas T, Courvoisier DS, Combescure C, Deom M, Perneger TV. Does prevalence matter to physicians in estimating post-test probability of disease ? A randomized trial. J Gen Intern Med. 2011 Apr;26(4):373-8. doi: 10.1007/s11606-010-1540-5. Epub 2010 Nov 4. PMID: 21053091; PMCID: PMC3055966. https://archive-ouverte.unige.ch/unige:25179</p
Thinker, Soldier, Scribe: cross-sectional study of researchers' roles and author order in the <i>Annals of Internal Medicine</i>
No full textHow researchers' contributions relate to author order on the byline remains unclear. We sought to identify researchers' contributions associated with author order, and to explore the existence of author profiles
Applying new strategies for the national adaptation, updating, and dissemination of trustworthy guidelines: Results from the Norwegian adaptation of the antithrombotic therapy and the prevention of thrombosis, 9th Ed: American college of chest physicians
No full textBACKGROUND: The Antithrombotic Therapy and the Prevention of Thrombosis, 9th Edition: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (AT9) represent trustworthy international guidelines for antithrombotic treatment and thromboprophylaxis. We describe major changes to the format and content resulting from applying new strategies for guideline adaptation and dissemination.RESULTS: We applied a novel presentation format to 333 recommendations from 11 of the 15 management chapters in AT9 and condensed and restructured them into 249 recommendations in a multilayered format. We added additional relevant information, such as 29 bestpractice statements about new oral anticoagulants and practical information sections for 121 recommendations. Common reasons for modifications included feasibility of the recommendations in a national context, disagreement with applied baseline risk estimates, and reevaluation of the balance between the benefits and harms of interventions in relation to assumed typical patient preferences and values. The adapted guideline was published and disseminated online in November 2013.METHODS: A Norwegian guideline panel of 46 experts completed a structured and systematic adaptation process, updated the recommendations based on new evidence, and rewrote the recommendations in an electronic multilayered presentation format. We published the adapted guideline using the web-based Making GRADE the Irresistible Choice Guideline Authoring and Publication Platform.CONCLUSIONS: New strategies for adapting, updating, and disseminating trustworthy guidelines proved feasible and will provide Norwegian health-care professionals and patients with up-to-date guidance tailored to national circumstances. © 2014 AMERICAN COLLEGE OF CHEST PHYSICIANS.Adam SS, 2012, ANN INTERN MED, V157, P796, DOI 10.7326-0003-4819-157-10-201211200-00532; Agoritsas T, CHEST IN PRESS, DOI [10.1378-chest.14-1366, DOI 10.1378-CHEST.14-1366]; Bates SM, 2012, CHEST S, V141; Cohen AT, 2013, NEW ENGL J MED, V368, P513, DOI 10.1056-NEJMoa1111096; COLLINS R, 1988, NEW ENGL J MED, V318, P1162, DOI 10.1056-NEJM198805053181805; Cook DA, 2013, PLOS ONE, V8, DOI 10.1371-journal.pone.0080318; Dentali F, 2007, ANN INTERN MED, V146, P278; Di Nisio M, 2012, COCHRANE DB SYST REV, V2; Enden T, 2012, LANCET, V379, P31, DOI 10.1016-S0140-6736(11)61753-4; Falck-Ytter Y, 2012, CHEST S, V141, DOI DOI 10.1378-CHEST.11-2404; Farge D, 2013, J THROMB HAEMOST, V11, P56, DOI 10.1111-jth.12070; Flottorp SA, 2013, IMPLEMENT SCI, V8, DOI 10.1186-1748-5908-8-35; Gagliardi AR, 2011, IMPLEMENT SCI, V6, DOI 10.1186-1748-5908-6-26; Goldhaber SZ, 2011, NEW ENGL J MED, V365, P2167, DOI 10.1056-NEJMoa1110899; Grimshaw JM, 2012, IMPLEMENT SCI, V7, DOI 10.1186-1748-5908-7-50; Guyatt GH, 2012, CHEST, V141, p7S, DOI 10.1378-chest.1412S3; Guyatt GH, 2008, BRIT MED J, V336, P1049, DOI 10.1136-bmj.39493.646875.AE; Guyatt GH, 2008, BRIT MED J, V336, P995, DOI 10.1136-bmj.39490.551019.BE; Guyatt GH, 2008, BRIT MED J, V336, P924, DOI 10.1136-bmj.39489.470347.AD; Homma S, 2012, NEW ENGL J MED, V366, P1859, DOI 10.1056-NEJMoa1202299; Husted H, 2010, ACTA ORTHOP, V81, P599, DOI 10.3109-17453674.2010.525196; Januel JM, 2012, JAMA-J AM MED ASSOC, V307, P294, DOI 10.1001-jama.2011.2029; Kristiansen A, 2014, CHEST, V146, P727, DOI 10.1378-chest.13-2828; Merli G, 2001, ANN INTERN MED, V134, P191; Neumann I, 2012, ANN INTERN MED, V156, P710, DOI 10.7326-0003-4819-156-10-201205150-00421; Pedersen AB, 2011, J BONE JOINT SURG AM, V93A, P1281, DOI [10.2106-JBJS.J.00676, 10.2106-JBJSJ.00676]; Shiffman Richard N, 2005, BMC Med Inform Decis Mak, V5, P23, DOI 10.1186-1472-6947-5-23; Treweek S, 2013, IMPLEMENT SCI, V8, DOI 10.1186-1748-5908-8-6; Vandvik PO, 2013, CHEST, V144, P381, DOI 10.1378-chest.13-074613
Living Systematic Reviews: 2. Combining Human and Machine Effort
No full textNew approaches to evidence synthesis, which utilise human effort and machine automation in mutually reinforcing ways, can enhance the feasibility and sustainability of living systematic reviews. Human effort is a scarce and valuable resource, required when automation is impossible or undesirable, and includes contributions from online communities ('crowds') as well as more conventional contributions from review authors and information specialists. Automation can assist with some systematic review tasks, including searching, eligibility assessment, identification and retrieval of full text reports, extraction of data, and risk of bias assessment. Workflows can be developed in which human effort and machine automation can each enable the other to operate in more effective and efficient ways, offering substantial enhancement to the productivity of systematic reviews. This paper describes and discusses the potential - and limitations - of new ways of undertaking specific tasks in living systematic reviews, identifying areas where these human / machine 'technologies' are already in use, and where further research and development is needed. While the context is living systematic reviews, many of these enabling technologies apply equally to standard approaches to systematic reviewing
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