261 research outputs found
Une étude théorique et empirique du comportement des joueurs dans les enchÚres à un sou
Ce mĂ©moire correspond Ă l'Ă©tude thĂ©orique et empirique du comportement des joueurs prĂ©sents sur le site Internet d'enchĂšre Ă un sou bidou.ca. L'objectif premier est de caractĂ©riser l'effet du comportement des joueurs sur les profits des joueurs et de l'encanteur en utilisant les concepts de la thĂ©orie des jeux. Plus particuliĂšrement, avec une banque de donnĂ©es sur les enchĂšres s'Ă©tant dĂ©roulĂ©es entre le 16 mars 2010 et le 14 janvier 2011, nous effectuons une analyse thĂ©orique et Ă©conomĂ©trique des effets du comportement passĂ© des joueurs sur les profits des joueurs et l'encanteur. De cette façon, nous avons trouvĂ© que le comportement des joueurs avait effectivement un impact important dans les enchĂšres Ă un sou. Plus prĂ©cisĂ©ment, l'agressivitĂ© et la rĂ©putation influent significativement le dĂ©roulement du jeu, et par consĂ©quent les profits. Ainsi, les profits de bidou.ca sont Ă la baisses plus que les joueurs sont agressifs Ă miser et ont une forte rĂ©putation. D'autre part, parmi les joueurs gagnants, ĂȘtre agressif est avantageux et permet d'augmenter leur profit en espĂ©rance. MĂȘme constat, si le joueur joui d'une forte rĂ©putation avant d'entrer dans une enchĂšre. Plus encore, la prĂ©sence de trop grand nombre de joueurs puissants sur un site peut mener Ă la fermeture de celui-ci si la situation perdure longtemps.\ud
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MOTS-CLĂS DE LâAUTEUR : enchĂšre Ă un sou, thĂ©orie des jeux, jeu d'attrition, jeu de hasard, rĂ©putation, comportement, Ă©conomie comportementale, profi
Spherical Perspective on Learning with Batch Norm
Batch Normalization (BN) is a prominent deep learning technique. In spite of
its apparent simplicity, its implications over optimization are yet to be fully
understood. In this paper, we study the optimization of neural networks with BN
layers from a geometric perspective. We leverage the radial invariance of
groups of parameters, such as neurons for multi-layer perceptrons or filters
for convolutional neural networks, and translate several popular optimization
schemes on the unit hypersphere. This formulation and the associated
geometric interpretation sheds new light on the training dynamics and the
relation between different optimization schemes. In particular, we use it to
derive the effective learning rate of Adam and stochastic gradient descent
(SGD) with momentum, and we show that in the presence of BN layers, performing
SGD alone is actually equivalent to a variant of Adam constrained to the unit
hypersphere. Our analysis also leads us to introduce new variants of Adam. We
empirically show, over a variety of datasets and architectures, that they
improve accuracy in classification tasks. The complete source code for our
experiments is available at: https://github.com/ymontmarin/adamsr
Examining the prevalence of chronic homelessness among single adults according to national definitions in Canada
This article examines the prevalence of chronic homelessness when applying definitions used in Canada to a sample of homeless and vulnerably housed single adults enrolled in a multi-city longitudinal study. The federal governmentâs current definition, Reaching Home, identified the highest proportion of homeless single adults (31 percent; 95% CI = 27.2 â 34.1) as âchronically homeless.â Our findings suggest that the federal definitions of chronic homelessness, which are based on both shelter stays and periods of homelessness outside the shelter system, are double the size of this sub-population when compared to definitions based on shelter stays alone. Participants who were male, identified as Indigenous, and reported problematic drug use, were more likely to be chronically homeless for definitions based on any-kind of homelessness. The findings highlight the importance of counting unsheltered and hidden homelessness to estimate the number of single adults who are chronically homeless.Cet article examine la prĂ©valence de lâitinĂ©rance chronique lors de lâapplication de dĂ©finitions utilisĂ©es au Canada Ă un Ă©chantillon dâadultes cĂ©libataires sans abri et logĂ©s de façon vulnĂ©rable, inscrits dans une Ă©tude longitudinale multi-villes. La dĂ©finition actuelle du gouvernement fĂ©dĂ©ral, Reaching Home, a identifiĂ© la plus grande proportion dâadultes cĂ©libataires sans abri (31 pour cent ; 95 % CI = 27,2 - 34,1) comme «sans abri chronique». Nos rĂ©sultats suggĂšrent que les dĂ©finitions de lâitinĂ©rance chronique, qui sont basĂ©es Ă la fois sur les sĂ©jours en refuge et les pĂ©riodes dâitinĂ©rance en dehors du systĂšme de refuge, reprĂ©sentent le double de la taille de cette sous-population par rapport aux dĂ©finitions basĂ©es uniquement sur les sĂ©jours en refuge. Les participants qui Ă©taient de sexe masculin, sâidentifiaient comme indigĂšnes et dĂ©claraient avoir fait un usage problĂ©matique de drogues, Ă©taient plus susceptibles dâĂȘtre associĂ©s Ă lâitinĂ©rance chronique pour les dĂ©finitions basĂ©es sur tout type dâitinĂ©rance. Les rĂ©sultats soulignent lâimportance de compter lâitinĂ©rance non abritĂ©e et cachĂ©e pour estimer le nombre dâadultes cĂ©libataires qui sont chroniquement sans abri
A new generation of veryhigh stability BVA oscillators
International audienceA third generation of âOscilloquartzâ OCXO's using the technique of housing a BVA SC-cut crystal resonator and its associated oscillator components in double oven technology has been developed with the funding support of European Space Operations Centre (E.S.O.C). The main purpose is to provide a local oscillator for high performances ground clock. The main features targeted of that new â8607-C seriesâ are to get significant improvements compared to the classical âstate of the artâ 8607-B design in a better short term stability @ 1 sec in Allan variance, a better-low phase noise and outstanding short term stability and a better-high isolation from âpressure and humidityâ variations
Temporal Artery Flow Response during the Last Minute of a Head Up Tilt Test, in Relation with Orthostatic Intolerance after a 60 Day Head-Down Bedrest
OBJECTIVE: Check if the Temporal flow response to Tilt could provide early hemodynamic pattern in the minutes preceding a syncope during the Tilt test performed after a 60-d head down bedrest (HDBR). METHOD: Twenty-one men divided into 3 groups [Control (Con), Resistive Vibration (RVE) and Chinese Herb (Herb)] underwent a 60 day HDBR. Pre and Post HDBR a 20 min Tilt identified Finishers (F) and Non Finishers (NF). Cerebral (MCA), Temporal (TEMP), Femoral (FEM) flow velocity, were measured by Doppler during the Tilt. Blood pressure (BP) was measured by arm cuff and cardiopress. RESULTS AND DISCUSSION: Four of the 21 subjects were NF at the post HDBR Tilt test (Con gr:2, RVE gr: 1, Herb gr: 1). At 1 min and 10 s before end of Tilt in NF gr, FEM flow decreased less and MCA decreased more at post HDBR Tilt compared to pre (p<0.05), while in the F gr they changed similarly as pre. In NF gr: TEMP flow decreased more at post HDBR Tilt compared to pre, but only at 10 s before the end of Tilt (P<0.05). During the last 10 s a negative TEMP diastolic component appeared which induced a drop in mean velocity until Tilt arrest. CONCLUSION: The sudden drop in TEMP flow with onset of a negative diastolic flow preceding the decrease in MCA flow confirm that the TEMP vascular resistance respond more directly than the cerebral one to the cardiac output redistribution and that this response occur several seconds before syncope
Prevalence of attention deficit hyperactivity disorder in detention settings: A systematic review and meta-analysis
© 2018 Baggio, Fructuoso, Guimaraes, Fois, Golay, Heller, Perroud, Aubry, Young, Delessert, Gétaz, Tran and Wolff. Background: Previous studies have reported a high prevalence of attention deficit hyperactivity disorder (ADHD) among people living in detention (PLD) corresponding to a five- to ten-fold increase compared to the general population. Our main study objective was to provide an updated ADHD prevalence rate for PLD, including PLD in psychiatric units. Sub-objectives included (i) comparing different ways of assessing ADHD, including DSM-5 criteria and (ii) identifying which types of PLD are more likely to have ADHD. Methods: We conducted a systematic review and meta-analysis following the PRISMA guidelines and the MOOSE checklist. PubMed/Medline, PsycINFO, and Web of Sciences were searched combining "ADHD" and "prison" keywords and synonyms for articles published between January 1, 1966 and January 2, 2018. Potential sources of variation to the meta-analytic ADHD prevalence rate were investigated using meta-regressions and subgroups analyses. Results: The meta-analysis pooled 102 original studies including 69,997 participants. The adult ADHD prevalence rate was 26.2% (95% confidence interval: 22.7-29.6). Retrospective assessments of ADHD in childhood were associated with an increased prevalence estimate (41.1, 95% confidence interval: 34.9-47.2, p < 0.001). There was no significant difference in the prevalence estimate between screenings and clinical interviews in adulthood. Only three studies used the DSM-5 definition of ADHD and results were non-significantly different with other DSM versions. We found no difference according to participants' characteristics. Conclusion: Our results confirmed the high prevalence rate of ADHD among PLD, corresponding to a five-fold increase compared to the general population. In light of such high ADHD prevalence, our results reinforce the importance of addressing this critical public health issue by (i) systematically offering ADHD screening and diagnosis to all individuals entering detention, and (ii) delivering treatment, monitoring, and care for ADHD during and after detention. These strategies may help reduce recidivism and reincarceration, as well as violence in detention settings, in addition to improving the health and wellbeing of people living in detention. Additionally, our study suggests that using screening scales may be a reliable way of assessing ADHD, although caution is needed because a complete evaluation by an experienced clinician is required to provide a formal diagnosis
ULF waves in the lowâlatitude boundary layer and their relationship to magnetospheric pulsations: A multisatellite observation
On April 30 (day 120), 1985, the magnetosphere was compressed at 0923 UT and the subsolar magnetopause remained near 7 REgeocentric for âŒ2 hours, during which the four spacecraft Spacecraft Charging At High Altitude (SCATHA), GOES 5, GOES 6, and Active Magnetospheric Particle Tracer Explorers (AMPTE) CCE were all in the magnetosphere on the morning side. SCATHA was in the low-latitude boundary layer (LLBL) in the second half of this period. The interplanetary magnetic field was inferred to be northward from the characteristics of precipitating particle fluxes as observed by the low-altitude satellite Defense Meteorological Satellite Program (DMSP) F7 and also from absence of substorms. We used magnetic field and particle data from this unique interval to study ULF waves in the LLBL and their relationship to magnetic pulsations in the magnetosphere. The LLBL was identified from the properties of particles, including bidirectional field-aligned electron beams at âŒ200 eV. In the boundary layer the magnetic field exhibited both a 5â10 min irregular compressional oscillation and a broadband (ÎÆ/Æ âŒ 1) primarily transverse oscillations with a mean period of âŒ50 s and a left-hand sense of polarization about the mean field. The former can be observed by other satellites and is likely due to pressure variations in the solar wind, while the latter is likely due to a Kelvin-Helmholtz (K.-H.) instability occurring in the LLBL or on the magnetopause. Also, a strongly transverse âŒ3-s oscillation was observed in the LLBL. The magnetospheric pulsations, which exhibited position dependent frequencies, may be explained in terms of field line resonance with a broadband source wave, that is, either the pressure-induced compressional wave or the K.-H. wave generated in or near the boundary layer
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A robust, coupled approach for atomistic-continuum simulation.
This report is a collection of documents written by the group members of the Engineering Sciences Research Foundation (ESRF), Laboratory Directed Research and Development (LDRD) project titled 'A Robust, Coupled Approach to Atomistic-Continuum Simulation'. Presented in this document is the development of a formulation for performing quasistatic, coupled, atomistic-continuum simulation that includes cross terms in the equilibrium equations that arise due to kinematic coupling and corrections used for the calculation of system potential energy to account for continuum elements that overlap regions containing atomic bonds, evaluations of thermo-mechanical continuum quantities calculated within atomistic simulations including measures of stress, temperature and heat flux, calculation used to determine the appropriate spatial and time averaging necessary to enable these atomistically-defined expressions to have the same physical meaning as their continuum counterparts, and a formulation to quantify a continuum 'temperature field', the first step towards constructing a coupled atomistic-continuum approach capable of finite temperature and dynamic analyses
Proceedings from the Ice Hockey Summit III: Action on Concussion
The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these five objectives: 1) describe sport-related concussion (SRC) epidemiology, 2) classify prevention strategies, 3) define objective, diagnostic tests, 4) identify treatment, and 5) integrate science and clinical care into prioritized action plans and policy. Our action plan evolved from 40 scientific presentations. The 155 attendees (physicians, athletic trainers, physical therapists, nurses, neuropsychologists, scientists, engineers, coaches, and officials) voted to prioritize these action items in the final Summit session. 1) Establish a national and international hockey data base for SRC at all levels, 2) eliminate body checking in Bantam youth hockey games, 3) expand a behavior modification program (Fair Play) to all youth hockey levels, 4) enforce game ejection penalties for fighting in Junior A and professional hockey leagues, 5) establish objective tests to diagnose concussion at point of care (POC), and 6) mandate baseline testing to improve concussion diagnosis for all age groups. Expedient implementation of the Summit III prioritized action items is necessary to reduce the risk, severity, and consequences of concussion in the sport of ice hockey
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