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A Hybrid Model For Reducing Ecological Bias, Ruth Salway, Jon Wakefield

UW Biostatistics Working Paper Series

A major drawback of epidemiological ecological studies, in which the association between area-level summaries of risk and exposure are used to make inference about individual risk, is the difficulty in characterising within-area variability in exposure and confounder variables. To avoid ecological bias, samples of individual exposure/confounder data within each area are required. Unfortunately these may be difficult or expensive to obtain, particularly if large samples are required. In this paper we propose a new approach suitable for use with small samples. We combine a Bayesian non-parametric Dirichlet process prior with an estimating functions approach, and show that this model gives …

Health-Exposure Modelling And The Ecological Fallacy, Jon Wakefield, Gavin Shaddick

UW Biostatistics Working Paper Series

Recently there has been increased interest in modelling the association between aggregate disease counts and environmental exposures measured, for example via air pollution monitors, at point locations. This paper has two aims: first we develop a model for such data in order to avoid ecological bias; second we illustrate that modelling the exposure surface and estimating exposures may lead to bias in estimation of health effects. Design issues are also briefly considered, in particular the loss of information in moving from individual to ecological data, and the at-risk populations to consider in relation to the pollution monitor locations. The approach …

The Effects Of Usda Farm-Bill Restoration Programs On Prairie Voles (Microtus Ochrogaster) In The Barrens Region Of Kentucky, Jestin Clark

Masters Theses & Specialist Projects

Much of the area that is now west-central Kentucky historically existed as grass dominated ecosystems. Unfortunately, most of those grasslands are gone due mostly to disturbance suppression and conversion to agricultural lands. Federal, state, and nongovernmental agencies have, particularly within the last several decades, undertaken the responsibility and goal of preserving and attempting to restore many of North America's lost grasslands. The USDA in conjunction with local landowners has initiated the CRP (Conservation Reserve Program) and the CREP (Conservation Reserve Enhancement Program); two popular farm bill-based conservation programs. Among the many conservation practices that these programs fund is grassland restoration. …

Implications Of Spatial Autocorrelation And Dispersal For The Modeling Of Species Distributions, Volker Bahn

Biological Sciences Faculty Publications

Modeling the geographical distributions of wildlife species is important for ecology and conservation biology. Spatial autocorrelation in species distributions poses a problem for distribution modeling because it invalidates the assumption of independence among sample locations. I explored the prevalence and causes of spatial autocorrelation in data from the Breeding Bird Survey, covering the conterminous United States, using Regression Trees, Conditional Autoregressive Regressions (CAR), and the partitioning of variance. I also constructed a simulation model to investigate dispersal as a process contributing to spatial autocorrelation, and attempted to verify the connection between dispersal and spatial autocorrelation in species’ distributions in empirical …

Diets And Coexistence Of The Sea Urchins Lytechinus Variegatus And Arbacia Punctulata (Echinodermata) Along The Central Florida Gulf Coast, Janessa Cobb, John M. Lawrence

Integrative Biology Faculty and Staff Publications

The basis for coexistence of similar species is fundamental in community ecology. One mechanism for coexistence is differentiation of diets. Lytechinus variegatus and Arbacia punctulata coexist in different microhabitats along the Florida gulf coast. Their great difference in morphology might affect their choice of microhabitats and diet. We analyzed diets of both species at 1 offshore and 1 nearshore site where both occurred in relatively equal numbers, an offshore site dominated by A. punctulata and an offshore site dominated by L. variegatus. Gut contents were analyzed to determine the diet. A. punctulata prim. consumed sessile invertebrates except on dates …

Update - June 2005, Loma Linda University Center For Christian Bioethics

Update

In this issue:

-- Universal Access to Health Care and Religious Basis of Human Rights

Primary Prevention Healthcare Among Black American Men: Social Ecological Factors Predictive Of Prostate Cancer Early Detection Access, Virginia Diane Bush Agbonkhese Woods

Loma Linda University Electronic Theses, Dissertations & Projects

Access to healthcare requires individuals to have a place to go, a healthcare provider to see them, resources to obtain proper care, and the appropriate health services given in an appropriate timeframe. Non-Hispanic Black American men have the highest incidence rate of prostate cancer in the world, 180.6 per 100,000 (NCI, 2004). It is not clear as to why high rates persist, but higher death rates are associated with late detection. This mixed-methods ecological study was to investigate physician and Black male perceptions and practices regarding prostate cancer early detection with prostate specific antigen (PSA) blood test, and the digital …

Tularemia: Emergence/Re-Emergence, Jeannine M. Petersen, Martin E. Schriefer

Other Publications in Zoonotics and Wildlife Disease

Francisella tularensis is a gram-negative coccobacillus and the etiologic agent of the zoonotic disease tularemia. First described in 1911 in Tulare County, California, it has since been reported throughout the Northern Hemisphere, with natural infections reported among an unusually wide range of vertebrates and invertebrates. In recent years, tularemia has emerged in new geographic locations, populations, and settings. This review will serve to highlight mechanisms contributing to the recent emergence of tularemia as well as a repertoire of diagnostic tools useful for detecting and diagnosing disease.