527 research outputs found

    Geodesics of Random Riemannian Metrics

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    We analyze the disordered Riemannian geometry resulting from random perturbations of the Euclidean metric. We focus on geodesics, the paths traced out by a particle traveling in this quenched random environment. By taking the point of the view of the particle, we show that the law of its observed environment is absolutely continuous with respect to the law of the random metric, and we provide an explicit form for its Radon-Nikodym derivative. We use this result to prove a "local Markov property" along an unbounded geodesic, demonstrating that it eventually encounters any type of geometric phenomenon. We also develop in this paper some general results on conditional Gaussian measures. Our Main Theorem states that a geodesic chosen with random initial conditions (chosen independently of the metric) is almost surely not minimizing. To demonstrate this, we show that a minimizing geodesic is guaranteed to eventually pass over a certain "bump surface," which locally has constant positive curvature. By using Jacobi fields, we show that this is sufficient to destabilize the minimizing property.Comment: 55 pages. Supplementary material at arXiv:1206.494

    Public Perception of Pesticide Exposure in Vermont

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    Introduction: A pesticide is any substance intended for preventing, destroying, repelling, or mitigating any pest.1 The public generally believes that insects, diseases, and other pests need to be controlled but is also becoming concerned about the impact of pesticides on their health and the local ecosystem. Pesticide exposure occurs with public and private use. Studies indicate consumers have diverse levels of awareness, knowledge, and attitudes regarding pesticide use and health risks.2 The goal of this project is to identify levels of awareness, knowledge, and attitudes toward pesticide usage in Vermont to help State agencies focus public awareness and education.https://scholarworks.uvm.edu/comphp_gallery/1217/thumbnail.jp

    Modeling Partitions of Individuals

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    Despite the central role of self-assembled groups in animal and human societies, statistical tools to explain their composition are limited. We introduce a statistical framework for cross-sectional observations of groups with exclusive membership to illuminate the social and organizational mechanisms that bring people together. Drawing from stochastic models for networks and partitions, the proposed framework introduces an exponential family of distributions for partitions. We derive its main mathematical properties and suggest strategies to specify and estimate such models. A case study on hackathon events applies the developed framework to the study of mechanisms underlying the formation of self-assembled project teams

    Health Professionals and Public Awareness of Carbon Monoxide Poisoning in Vermont

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    Introduction. Carbon monoxide (CO) is the second leading cause of non-medical poisoning death in the United States. Between 1999 and 2012, Vermont saw the highest rates of CO poisoning deaths in New England. Public education and the use of CO alarms have been identified as important prevention strategies. We developed and distributed a survey to assess public and health professional knowledge of CO. Methods. A 21-question survey was designed, based on the validated Chicago Lead Knowledge Test, to assess knowledge about sources of CO exposure and symptoms and treatment of poisoning. Fifteen additional questions collected occupational and demographic information and preferred sources of educational information. Surveys were distributed over two months to the public, healthcare professionals, and emergency responders within Chittenden County, as well as physicians throughout Vermont. Survey responses were analyzed using SPSS. Results. There were 256 respondents. Healthcare professionals performed better than public respondents overall (public: mean correct=15.69, SD= 2.83, N=104; healthcare provider and emergency responder: mean correct= 17.5, SD= 2.23, N= 152). The survey questions which were most frequently answered incorrectly related to treatment and sources of exposure, as well as the similarity of CO poisoning to symptoms of influenza. Respondents preferred to receive information from printed and internet sources. Discussion. Medical professionals are more knowledgeable about carbon mon- oxide than the general public. Public education should include printed and online for- mats, focusing on important sources of exposure (particularly ice rinks), seeking treatment following symptoms, and similarity to flu symptoms.https://scholarworks.uvm.edu/comphp_gallery/1267/thumbnail.jp
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