2 resultados para clinical (human) or epidemiologic studies : risk factor assessment

em Digital Commons at Florida International University


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This study examined two competitive hypotheses: the double jeopardy hypothesis and the buffering effect hypothesis on whether parental divorce affects adopted children and non-adopted children similarly or differently. The double jeopardy hypothesis suggests that when adopted children experience their parents' divorce, they perform worse because they carry two risk factors, adoption status and parental divorce, while their non-adopted counterparts carry only the risk factor of their parents' divorce. The buffering effect hypothesis suggests that, being adopted children, their previous experiences of parental loss help them better deal with the later loss of their parents' divorce so their adoption status is a protective factor rather than a risk factor. ^ Secondary analyses of a nation-wide data set were executed using different statistical methods such as ANOVA and Chi-square on different outcome variables. The results indicated that there was no evidence supporting the double-jeopardy hypothesis. That is, adopted children from divorced families did not perform significantly worse than the non-adopted children from divorced families on any outcome variable. The results also indicated that there was only weak evidence supporting the buffering effect hypothesis. The general conclusion based on the results from most of the outcome variables suggest that adopted children from divorced families do not perform differently than the biological children from divorced families. ^

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Habitat selection decisions by consumers has the potential to shape ecosystems. Understanding the factors that influence habitat selection is therefore critical to understanding ecosystem function. This is especially true of mesoconsumers because they provide the link between upper and lower tropic levels. We examined the factors influencing microhabitat selection of marine mesoconsumers – juvenile giant shovelnose rays (Glaucostegus typus), reticulate whiprays (Himantura uarnak), and pink whiprays (H. fai) – in a coastal ecosystem with intact predator and prey populations and marked spatial and temporal thermal heterogeneity. Using a combination of belt transects and data on water temperature, tidal height, prey abundance, predator abundance and ray behavior, we found that giant shovelnose rays and reticulate whiprays were most often found resting in nearshore microhabitats, especially at low tidal heights during the warm season. Microhabitat selection did not match predictions derived from distributions of prey. Although at a course scale, ray distributions appeared to match predictions of behavioral thermoregulation theory, fine-scale examination revealed a mismatch. The selection of the shallow nearshore microhabitat at low tidal heights during periods of high predator abundance (warm season) suggests that this microhabitat may serve as a refuge, although it may come with metabolic costs due to higher temperatures. The results of this study highlight the importance of predators in the habitat selection decisions of mesoconsumers and that within thermal gradients, factors, such as predation risk, must be considered in addition to behavioral thermoregulation to explain habitat selection decisions. Furthermore, increasing water temperatures predicted by climate change may result in complex trade-offs that might have important implications for ecosystem dynamics.