26,951 research outputs found

    The management of context-sensitive features: A review of strategies

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    In this paper, we review five heuristic strategies for handling context- sensitive features in supervised machine learning from examples. We discuss two methods for recovering lost (implicit) contextual information. We mention some evidence that hybrid strategies can have a synergetic effect. We then show how the work of several machine learning researchers fits into this framework. While we do not claim that these strategies exhaust the possibilities, it appears that the framework includes all of the techniques that can be found in the published literature on context-sensitive learning

    Prevalence and correlates of antibodies to Neospora caninum in dogs in Portugal

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    Neosporosis, caused by Neospora caninum, is an important cause of abortion in cattle and of neurological disease in dogs. This study investigated the prevalence and correlates of antibodies to N. caninum in 441 dogs from the five regions of mainland Portugal. A commercial competitive enzyme-linked immunosorbent assay (cELISA) was used and specific antibodies were detected in 35 (7.9%) dogs. Seroprevalence levels were significantly different among some of the studied regions, as well as between stray dogs (13.6%) and hunting dogs (1.7%). The difference between seropositivity in dogs presenting musculoskeletal or neurological signs (21.4%) and that in animals without clinical signs compatible with neosporosis (5.6%) was close to statistical significance. This is the first report on the seroprevalence of N. caninum in dogs in Portugal. Neosporosis should be considered in the differential diagnosis of neurological disorders of dogs.National Funds through FCT - Foundation for Science and Technology under the Strategic Project [PEst-OE/AGR/UI0115/2014]; FCT [SFRH/BPD/44082/2008]info:eu-repo/semantics/publishedVersio

    Stability, Resonance and Lyapunov Inequalities for Periodic Conservative Systems

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    This paper is devoted to the study of Lyapunov type inequalities for periodic conservative systems. The main results are derived from a previous analysis which relates the best Lyapunov constants to some especial (constrained or unconstrained) minimization problems. We provide some new results on the existence and uniqueness of solutions of nonlinear resonant and periodic systems. Finally, we present some new conditions which guarantee the stable boundedness of linear periodic conservative systems.Comment: 19 page

    Factors associated with not seeking professional help or disclosing intent prior to suicide : A study of medical examiners' records in Nova Scotia

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    Individual-level data from clinical settings lack information on people who did not seek professional help prior to suicide. We used records of the Nova Scotia Medical Examiner Service (NSMES) to compare people who had contact with a health professional prior to suicide with those who did not.We linked data from the NSMES to routine administrative data of the province.The NSMES recorded 108 suicides in Nova Scotia from January 1, 2006, to December 31, 2006; there were 90 male and 18 female suicide deaths. Mean and median age at death were 44.73 (SD 13.33) and 44 years, respectively. Patients aged 40 to 49 years made up one-third of the cases (n = 35) and this was the decade of life with the highest number of suicides. This was also the group least likely to have suicidal intent recorded in the NSMES files (χ(2) = 3.86, df = 1, P = 0.05). Otherwise, there were no significant differences between people who sought help, or disclosed intent, prior to suicide and people who did not. The samples in all cases were predominately male and single.People aged 40 to 49 years were the age group with the highest absolute number of suicides, but were the least likely to have suicidal intent recorded in the NSMES files. This finding merits further investigation. Medical examiner or coroner data may provide additional information not obtained elsewhere for the surveillance of suicide

    Functional Inequalities: New Perspectives and New Applications

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    This book is not meant to be another compendium of select inequalities, nor does it claim to contain the latest or the slickest ways of proving them. This project is rather an attempt at describing how most functional inequalities are not merely the byproduct of ingenious guess work by a few wizards among us, but are often manifestations of certain natural mathematical structures and physical phenomena. Our main goal here is to show how this point of view leads to "systematic" approaches for not just proving the most basic functional inequalities, but also for understanding and improving them, and for devising new ones - sometimes at will, and often on demand.Comment: 17 pages; contact Nassif Ghoussoub (nassif @ math.ubc.ca) for a pre-publication pdf cop

    Investigation of critical burning of fuel droplets

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    Fuel droplets were simulated by porous spheres having diameters in the range 0.63 to 1.9 cm and combustion tests were conducted at pressures up to 78 atm in a quiescent cold air environment. Measurements were made of the burning rate and liquid surface temperature during steady combustion. A high pressure flat flame burner apparatus is under development in order to allow testing of high pressure droplet burning in a combustion gas environment. Work was continued on the high pressure strand combustion characteristics of liquid fuels, with the major emphasis on hydrazine. Data was obtained on the burning rate and liquid surface temperatures at pressures in the range 7 to 500 psia. The response of a burning liquid monopropellant to imposed pressure oscillations is being investigated

    Land-Based Pollution in the Arctic Ocean: Canadian Actions in a Regional and Global Context

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    The occurrence of high concentrations of anthropogenic contaminants in the Arctic environment has been a concern for many years. The present overview of the current threats of pollutants from atmospheric, oceanic, river, and local pathways uses results from recent national, pan-Arctic, and international reports to emphasize the need to address issues arising from climate change, particularly the effect of changing weather patterns on contaminant transportation via both waterways and the atmosphere. Regional and international actions over the past two decades attempting to manage pollutants in the Arctic environment from landbased sources have produced recommendations that focus primarily on increasing cooperation in research and monitoring activities, not only among the Arctic governments themselves, but also including the interests and resources of non-polar countries. Our Canadian perspective on the domestic and circumpolar context of the issue, with regard to mechanisms exerting immediate control on the spread of contaminants, describes national programs and policies that are important to the Canadian North and to the Arctic community as a whole. All levels of Canadian government, as well as foreign governments, have joined in working towards safeguarding the Arctic and other marine environments. Prioritization of concerns is an important approach to tackling the numerous current issues related to the spread of contaminants in the Arctic environment. The government needs to give increased priority to the North, and that action needs to be taken in partnership with local communities and pursued at the regional, national, and international levels.La présence de fortes concentrations de contaminants anthropogéniques dans l’environnement arctique est une source d’inquiétude depuis des années. Le présent aperçu des menaces actuelles découlant des polluants provenant de l’atmosphère, des océans, des fleuves et rivières ainsi que de la région s’appuie sur les résultats de récents rapports d’envergure nationale, panarctique et internationale pour faire ressortir la nécessité de résoudre les enjeux résultant du changement climatique, plus particulièrement l’effet de la situation météorologique changeante sur le transport des contaminants, tant par les cours d’eau que par l’atmosphère. Ces vingt dernières années, les mesures prises à l’échelle régionale et internationale pour tenter de gérer les polluants de sources terrestres dans l’environnement arctique ont donné lieu à des recommandations qui visent principalement une coopération accrue sur le plan des activités de recherche et de surveillance, non seulement au sein des gouvernements arctiques mêmes, mais aussi en faisant appel aux intérêts et aux ressources des pays non polaires. Notre perspective canadienne sur le contexte intérieur et circumpolaire à propos de cette question, en ce qui a trait aux mécanismes qui exercent un contrôle immédiat sur la propagation des contaminants, décrit des politiques et des programmes nationaux qui sont importants aux yeux des collectivités du Nord canadien et de l’Arctique dans l’ensemble. Tous les échelons de gouvernement canadien, de même que de gouvernements étrangers, travaillent de concert pour protéger l’environnement de l’Arctique et d’autres environnements marins. La priorisation des préoccupations constitue une manière importante de s’attaquer aux nombreux enjeux actuels relatifs à la propagation des contaminants dans l’environnement arctique. Le gouvernement doit accorder une priorité accrue au Nord, et cela doit se faire en collaboration avec les collectivités de la région, en plus de s’étendre aux échelons régionaux, nationaux et internationaux
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