4,140 research outputs found

    ADVICE, INFLUENCE, AND INDEPENDENCE: ADOLESCENT NUTRITIONAL PRACTICES AND OUTCOMES IN BELFAST, NORTHERN IRELAND

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    The goal of this dissertation is to discuss relationships between the sociocultural environment and nutritional status outcomes in an urban industrialized city with high rates of poverty. The purpose is to highlight the complex web of factors shaping nutritional status outcomes and move beyond cause and effect approaches to nutrition in an environment where obesity is a central nutritional concern. To accomplish this goal, I examine a range of factors that relate to adolescent nutritional practices and nutritional status outcomes in a sample population of adolescents living in Belfast, Northern Ireland. I discuss connections between social locations such as age, gender, geographic area, and socioeconomic status. I also highlight the range of nutritional status outcomes observed in the sample population, while examining broader social, political, and economic aspects of the lives of adolescents that differentially shape nutrition-related experiences in the city. Finally, I demonstrate that adolescents occupy a complex social location in which autonomy, advice, and influence from sociocultural and political-economic factors shape their diet and exercise practices and nutritional status outcomes in multi-faceted, and at times unexpected, ways. In doing so, I emphasize the benefits of a localized, rather than a globalized approach to nutritional concerns such as obesity

    Testing Hypotheses for Exotic Plant Success: Parallel Experiments in the Native and Introduced Ranges

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    A central question in ecology concerns how some exotic plants that occur at low densities in their native range are able to attain much higher densities where they are introduced. This question has remained unresolved in part due to a lack of experiments that assess factors that affect the population growth or abundance of plants in both ranges. We tested two hypotheses for exotic plant success: escape from specialist insect herbivores and a greater response to disturbance in the introduced range. Within three introduced populations in Montana, USA, and three native populations in Germany, we experimentally manipulated insect herbivore pressure and created small-scale disturbances to determine how these factors affect the performance of houndstongue (Cynoglossum officinale), a widespread exotic in western North America. Herbivores reduced plant size and fecundity in the native range but had little effect on plant performance in the introduced range. Small-scale experimental disturbances enhanced seedling recruitment in both ranges, but subsequent seedling survival was more positively affected by disturbance in the introduced range. We combined these experimental results with demographic data from each population to parameterize integral projection population models to assess how enemy escape and disturbance might differentially influence C. officinale in each range. Model results suggest that escape from specialist insects would lead to only slight increases in the growth rate (λ) of introduced populations. In contrast, the larger response to disturbance in the introduced vs. native range had much greater positive effects on λ. These results together suggest that, at least in the regions where the experiments were performed, the differences in response to small disturbances by C. officinale contribute more to higher abundance in the introduced range compared to at home. Despite the challenges of conducting experiments on a wide biogeographic scale and the logistical constraints of adequately sampling populations within a range, this approach is a critical step forward to understanding the success of exotic plants

    2006 Housing in the Nation's Capital

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    Explores the interdependent relationship between public school systems and housing markets, and examines the ability of coordinated investment in affordable housing and quality education to revitalize Washington, D.C., metropolitan area neighborhoods

    Avoiding unintentional eviction from integral projection models

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    Integral projection models (IPMs) are increasingly being applied to study size-structured populations. Here we call attention to a potential problem in their construction that can have important consequences for model results. IPMs are implemented using an approximating matrix and bounded size range. Individuals near the size limits can be unknowingly "evicted" from the model because their predicted future size is outside the range. We provide simple measures for the magnitude of eviction and the sensitivity of the population growth rate (lambda) to eviction, allowing modelers to assess the severity of the problem in their IPM. For IPMs of three plant species, we found that eviction occurred in all cases and caused underestimation of the population growth rate (lambda) relative to eviction-free models; it is likely that other models are similarly affected. Models with frequent eviction should be modified because eviction is only possible when size transitions are badly mis-specified. We offer several solutions to eviction problems, but we emphasize that the modeler must choose the most appropriate solution based on an understanding of why eviction occurs in the first place. We recommend testing IPMs for eviction problems and resolving them, so that population dynamics are modeled more accurately

    Backbone and side chain H-1, N-15 and C-13 assignments for the oxidised and reduced forms of the oxidoreductase protein DsbA from Staphylococcus aureus

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    The function and dynamics of the thiol-disulfide oxidoreductase DsbA in the low-GC gram positive bacterium, Staphylococcus aureus, are yet to be elucidated. Here we report 13C, 15N and 1H assignments for the oxidised and reduced forms of SaDsbA as a prelude to further studies on the enzyme
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