Une étude théorique et empirique du comportement des joueurs dans les enchères à un sou

Ce mémoire correspond à l'étude théorique et empirique du comportement des joueurs présents sur le site Internet d'enchère à un sou bidou.ca. L'objectif premier est de caractériser l'effet du comportement des joueurs sur les profits des joueurs et de l'encanteur en utilisant les concepts de la théorie des jeux. Plus particulièrement, avec une banque de données sur les enchères s'étant déroulées entre le 16 mars 2010 et le 14 janvier 2011, nous effectuons une analyse théorique et économétrique des effets du comportement passé des joueurs sur les profits des joueurs et l'encanteur. De cette façon, nous avons trouvé que le comportement des joueurs avait effectivement un impact important dans les enchères à un sou. Plus précisément, l'agressivité et la réputation influent significativement le déroulement du jeu, et par conséquent les profits. Ainsi, les profits de bidou.ca sont à la baisses plus que les joueurs sont agressifs à miser et ont une forte réputation. D'autre part, parmi les joueurs gagnants, être agressif est avantageux et permet d'augmenter leur profit en espérance. Même constat, si le joueur joui d'une forte réputation avant d'entrer dans une enchère. Plus encore, la présence de trop grand nombre de joueurs puissants sur un site peut mener à la fermeture de celui-ci si la situation perdure longtemps.\ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : enchère à un sou, théorie des jeux, jeu d'attrition, jeu de hasard, réputation, comportement, économie 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 $L_2$ 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 government’s current definition, Reaching Home, identified the highest proportion of homeless single adults (31 percent; 95% CI = 27.2 – 34.1) as “chronically homeless.” 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 prévalence de l’itinérance chronique lors de l’application de définitions utilisées au Canada à un échantillon d’adultes célibataires sans abri et logés de façon vulnérable, inscrits dans une étude longitudinale multi-villes. La définition actuelle du gouvernement fédéral, Reaching Home, a identifié la plus grande proportion d’adultes célibataires sans abri (31 pour cent ; 95 % CI = 27,2 - 34,1) comme «sans abri chronique». Nos résultats suggèrent que les définitions de l’itinérance chronique, qui sont basées à la fois sur les séjours en refuge et les périodes d’itinérance en dehors du système de refuge, représentent le double de la taille de cette sous-population par rapport aux définitions basées uniquement sur les séjours en refuge. Les participants qui étaient de sexe masculin, s’identifiaient comme indigènes et déclaraient avoir fait un usage problématique de drogues, étaient plus susceptibles d’être associés à l’itinérance chronique pour les définitions basées sur tout type d’itinérance. Les résultats soulignent l’importance de compter l’itinérance non abritée et cachée pour estimer le nombre d’adultes célibataires qui sont chroniquement sans abri

A new generation of veryhigh stability BVA oscillators

International audienceA third generation of “Oscilloquartz” 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 “8607-C series” are to get significant improvements compared to the classical “state of the art” 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 “pressure and humidity” 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 low‐latitude 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 ∼2 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 ∼200 eV. In the boundary layer the magnetic field exhibited both a 5–10 min irregular compressional oscillation and a broadband (Δƒ/ƒ ∼ 1) primarily transverse oscillations with a mean period of ∼50 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 ∼3-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

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