136 research outputs found

    Consistent Price Systems under Model Uncertainty

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    We develop a version of the fundamental theorem of asset pricing for discrete-time markets with proportional transaction costs and model uncertainty. A robust notion of no-arbitrage of the second kind is defined and shown to be equivalent to the existence of a collection of strictly consistent price systems.Comment: 19 page

    Stochastic Target Games and Dynamic Programming via Regularized Viscosity Solutions

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    We study a class of stochastic target games where one player tries to find a strategy such that the state process almost-surely reaches a given target, no matter which action is chosen by the opponent. Our main result is a geometric dynamic programming principle which allows us to characterize the value function as the viscosity solution of a non-linear partial differential equation. Because abstract mea-surable selection arguments cannot be used in this context, the main obstacle is the construction of measurable almost-optimal strategies. We propose a novel approach where smooth supersolutions are used to define almost-optimal strategies of Markovian type, similarly as in ver-ification arguments for classical solutions of Hamilton--Jacobi--Bellman equations. The smooth supersolutions are constructed by an exten-sion of Krylov's method of shaken coefficients. We apply our results to a problem of option pricing under model uncertainty with different interest rates for borrowing and lending.Comment: To appear in MO

    Un quart de siÚcle plus tard : notre malade...

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    Psychiatre depuis 30 ans, l'auteur ramÚne au souvenir, à l'aide de son expérience, l'histoire de l'évolution de l'institution Robert-Giffard aussi bien que l'évolution de la psychiatrie au Québec. Il revoit les conditions de vie des patients et celles du personnel depuis le début des années 50. Il nous permet de se souvenir que le traitement scientifique et le progrÚs social ont permis une approche plus humaine envers ces personnes étiquetées malades mentaux.The author, a psychiatrist, has worked at the Centre hospitalier Robert Giffard (formerly St. Michel-Archange) at Quebec, for almost 30 years. In this article he brings to life, using many of his experiences, the history of the evolution of this institution as well as that of the evolution of Quebec psychiatry as a whole. He reviews the living conditions of the patients and those of the treatment staff since the beginning of the 1950* s. He allows us to remember that scientific as well as social progress have permitted a more humane approach to those people whom we have labelled insane

    Weak Dynamic Programming for Generalized State Constraints

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    We provide a dynamic programming principle for stochastic optimal control problems with expectation constraints. A weak formulation, using test functions and a probabilistic relaxation of the constraint, avoids restrictions related to a measurable selection but still implies the Hamilton-Jacobi-Bellman equation in the viscosity sense. We treat open state constraints as a special case of expectation constraints and prove a comparison theorem to obtain the equation for closed state constraints.Comment: 36 pages;forthcoming in 'SIAM Journal on Control and Optimization

    Common Crowd Dynamics: Shaping Behavioral Intention Models

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    As the human population grows, so too does the need to understand human behavior. One particularly important aspect of human behavior is how it changes within conglomerations of people, i.e. crowds. In this thesis, a method for modeling crowd behavior is proposed. This method draws inspiration from the concept of behavioral intention and the related forces of attitudes, influences, and social norms. These topics are first defined and detailed, followed by a survey of related research. Next, the model is presented and adapted to three common crowd dynamics, each stressing a different component of behavioral intention. Observations are made about these models, and extensions to the models and directions for future research are considered

    No Evidence of a Common DNA Variant Profile Specific to World Class Endurance Athletes

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    There are strong genetic components to cardiorespiratory fitness and its response to exercise training. It would be useful to understand the differences in the genomic profile of highly trained endurance athletes of world class caliber and sedentary controls. An international consortium (GAMES) was established in order to compare elite endurance athletes and ethnicity-matched controls in a case-control study design. Genome-wide association studies were undertaken on two cohorts of elite endurance athletes and controls (GENATHLETE and Japanese endurance runners), from which a panel of 45 promising markers was identified. These markers were tested for replication in seven additional cohorts of endurance athletes and controls: from Australia, Ethiopia, Japan, Kenya, Poland, Russia and Spain. The study is based on a total of 1520 endurance athletes (835 who took part in endurance events in World Championships and/or Olympic Games) and 2760 controls. We hypothesized that world-class athletes are likely to be characterized by an even higher concentration of endurance performance alleles and we performed separate analyses on this subsample. The meta-analysis of all available studies revealed one statistically significant marker (rs558129 at GALNTL6 locus, p = 0.0002), even after correcting for multiple testing. As shown by the low heterogeneity index (I2 = 0), all eight cohorts showed the same direction of association with rs558129, even though p-values varied across the individual studies. In summary, this study did not identify a panel of genomic variants common to these elite endurance athlete groups. Since GAMES was underpowered to identify alleles with small effect sizes, some of the suggestive leads identified should be explored in expanded comparisons of world-class endurance athletes and sedentary controls and in tightly controlled exercise training studies. Such studies have the potential to illuminate the biology not only of world class endurance performance but also of compromised cardiac functions and cardiometabolic diseases

    Sport, genetics and the `natural athlete': The resurgence of racial science

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    This article explores the ethical implications of recent discussions that naturalize the relationship between race, the body and sport within the frame of genetic science. Many suggestions of a racially distributed genetic basis for athletic ability and performance are strategically posited as a resounding critique of the `politically correct' meta-narratives of established sociological and anthropological forms of explanation that emphasize the social and cultural construction of race. I argue that this use of genetic science in order to describe and explain common-sense impressions of racial physiology and sporting ability is founded on erroneous premises of objectivity and disinterest, and inflates the analytical efficacy of scientific truth claims. I suggest that assertions of a value-free science of racial athletic ability reify race as inherited permanent biological characteristics that produce social hierarchies and are more characteristic of a longer history of `racial science'

    Papers, posters, and keynote presented at the 26th Polar Libraries Colloquy, hosted by the University of Alaska Fairbanks, Fairbanks, Alaska, USA 10 – 15 July 2016

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    Published July 2023 by the University of Alaska Anchorage, UAA/APU Consortium Library, and edited by Daria O. Carle. Copyright in individual papers is held by the contributors. A digital copy of this publication can be found at https://polarlibraries.org/colloquy-proceedings/ and in ScholarWorks, the University of Alaska’s Institutional Repository, https://scholarworks.alaska.edu/. A copy of the 2016 Colloquy program is also available at https://polarlibraries.org/colloquy-proceedings/. Further information on the Polar Libraries Colloquy, including details of membership and upcoming conferences, is available at https://polarlibraries.orgHistory of Polar Information Science / Working in Antarctica: Mapping a Changing Experience through the British Antarctic Survey / GĂ©oindex+: A Geospatial Platform for Northern Historical and Research Data / Establishing Criteria for the Development of the “Northern Collection” at UniversitĂ© Laval’s Library: An Exploratory Approach / Introducing Two New Reserach Platforms: seaiceportal.de and expedition.awi.de (abstract only) / Establishing a Digital Library Service for the Inuvialuit Settlement Region / Changing Patterns of Polar Research / Mapping the Rescue of an Archive / Byrd 1933: Films from the Discovery Lecture Series / History of the Elmer E. Rasmuson Library and Its Rare Books Collection / A Roadmap to Navigate the Range of Polar Libraries, Databases, and Archives Now Available Online / Mapping Change with Finna in an Arctic Research Joint Library (paper not listed in program) / Mapping Chang in a Small Library Environment: From Reading Room to Communications Center (abstract only) / The Continued Evolution of the Cold Regions Bibliography Project: Current Status of the Antarctic Bibliography and the Antarctic Journal of the United States and its Predecessors / Connect the North: The Arctic Connect Project / Languages and Dialects in the Digital Library North (abstract only) / Bridging Arctic Indigenous Knowledge with the Digital World: Sharing Indigenous Ways of Knowing in Partnership with Arctic Communities (abstract only) / The Canadian Consortium for Arctic Data Interoperability (abstract and poster

    Physiological Correlates of Volunteering

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    We review research on physiological correlates of volunteering, a neglected but promising research field. Some of these correlates seem to be causal factors influencing volunteering. Volunteers tend to have better physical health, both self-reported and expert-assessed, better mental health, and perform better on cognitive tasks. Research thus far has rarely examined neurological, neurochemical, hormonal, and genetic correlates of volunteering to any significant extent, especially controlling for other factors as potential confounds. Evolutionary theory and behavioral genetic research suggest the importance of such physiological factors in humans. Basically, many aspects of social relationships and social activities have effects on health (e.g., Newman and Roberts 2013; Uchino 2004), as the widely used biopsychosocial (BPS) model suggests (Institute of Medicine 2001). Studies of formal volunteering (FV), charitable giving, and altruistic behavior suggest that physiological characteristics are related to volunteering, including specific genes (such as oxytocin receptor [OXTR] genes, Arginine vasopressin receptor [AVPR] genes, dopamine D4 receptor [DRD4] genes, and 5-HTTLPR). We recommend that future research on physiological factors be extended to non-Western populations, focusing specifically on volunteering, and differentiating between different forms and types of volunteering and civic participation
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