Thesis (M.S.)--University of Montana, 2007. / Title from title screen. Description based on contents viewed Aug. 13, 2007. Includes bibliographical references (p. 52-53).

Thesis (M.S.)--Oregon State University, 1986. / Typescript (photocopy). Includes bibliographical references (leaves 38-40). Also available on the World Wide Web.

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Dopamine has an important role in normal cognition and reward processing, both of which are impaired in disorders involving dopamine dysfunction such as addiction, schizophrenia, and Parkinson's disease. However, our understanding of the interplay between different aspects of the dopamine system and reward-guided behavior in humans is limited. Food is an important type of reward that is critical for survival and impacts the decisions we make every day. Here, we characterize the relationship between two food-reward related phenotypes and dopamine synthesis capacity (related to tonic dopamine) as well as dopamine D1 and D2 receptor availability in healthy humans. First, we examined the link between dopamine synthesis and receptor availability and body mass regulation in 117 individuals with body mass index (BMI) values ranging from normal to obese. We found that current BMI was related to a pattern of increased dopamine synthesis in the hypothalamus, a region important for homeostatic control of appetite, but decreased dopamine D₂ receptor availability in the midbrain, where D₂ autoreceptors regulate dopamine release throughout the brain. This suggests that increased BMI is related to a dopamine imbalance between homeostatic drivers of appetite and reward system regulatory control mechanisms that could result in an overactive, unregulated intake of food. Building on this finding, we studied the link between dopamine synthesis capacity and receptor availability and an important food-reward related behavior, foraging. Fifty-seven healthy volunteers completed a computer-based foraging task where we measured their threshold for leaving one group of rewards to search for another in four different reward environments varying from a low to high rate of reward receipt. We found that two particular patterns of dopamine synthesis and receptor availability in the anterior cingulate cortex and basal ganglia were linked to the amount that individuals changed their threshold based on the reward rate of the environment. Finally, since the prefrontal cortex is known to be important for reward-guided behavior, we implemented two methodological advancements aimed to address limitations that make it difficult to measure cortical dopamine in humans with PET imaging. The first method involves partial volume correction and surface-based smoothing in order to increase the signal to noise in the cortex. The second method is a data-driven PET data parcellation and automated reference region selection algorithm to optimize the voxels included in the reference region. In conclusion, we have characterized the dopaminergic contribution of two different foodreward guided phenotypes and have developed two techniques that will aid future research on the role of cortical dopamine. Understanding the neural mechanisms underlying these rewardguided behaviors helps us to not only understand normal behavior, but also serves as a reference for comparison when studying related pathological states.

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In a perfect market with no limit on arbitrage, the price movements or returns of an index futures contract must be perfectly and positively correlated with those of the underlying cash index and the component stocks of the index. However, transaction costs, capital limits and regulatory restrictions reduce arbitrage efficiency which is being revealed by a wealth of findings that index futures and the underlying cash assets do not move in perfect unison. It is an important issue to practitioners, exchange and regulatory authorities, and academics to understand which and how different market and idiosyncratic factors drive the dynamic temporal relationships between an index futures contract and the related individual cash assets. Chapter 1 of the thesis examines how and to what extent the sampling frequency for return calculation affects the intraday correlation and lead-lag relationship between index futures, the underlying cash index and individual cash assets. Chapter 2 tests how and to what extent index weight, liquidity, idiosyncratic information of a single cash stock, market conditions and regulatory restrictions affect the intraday correlation between the futures and individual cash asset. Following the line of argument in Chapter 2, Chapter 3 analyzes the impact of stock-specific and market factors on the intraday lead-lag relationship between the futures and single cash assets. The study deduces that stock-specific and market factors significantly affect the intraday dynamic relationship between index futures and individual cash assets and it is a phenomenon that could be explained by the optimal strategies adopted by index arbitrageurs.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Pulmonary complications including acute chest syndrome are leading causes of sickle cell disease related morbidity and mortality. Studies have shown that pulmonary changes can be detected during childhood. Spirometry is the current standard for measuring lung function. Growing evidence suggests that lung clearance index (LCI) is as sensitive as spirometry in identifying pulmonary changes in pediatric patients. Our cross-sectional study compared the sensitivity of LCI to spirometry in the detection of early pulmonary changes in children with sickle cell disease. Our results show that LCI significantly correlates to FEV1% predicted (Spearman’s coefficient -0.44, p = 0.003), FVC % predicted (Spearman’s coefficient -0.44, p = 0.006) and FEF25-75 (Spearman’s coefficient -0.49, p <0.001). Using receiver operating characteristic (ROC) curves, LCI was found to be more sensitive than spirometry, but less specific. The data support LCI’s use as a test to screen for pulmonary changes in children with sickle cell disease. Earlier monitoring of lung function will allow for preventative therapies and delayed progression of pulmonary dysfunction.

Due to persistent and serious threats from natural disasters around the globe, many have turned to resilience and vulnerability research to guide disaster preparation, recovery, and adaptation decisions. In response, scholars and practitioners have put forth a variety of disaster indices, based on quantifiable metrics, to gauge levels of resilience and vulnerability. However, few indices are empirically validated using observed disaster impacts and, as a result, it is often unclear which index should be preferred for each decision at hand. Thus, we compare and empirically validate five of the top U.S. disaster indices, including three resilience indices and two vulnerability indices. We use observed disaster losses, fatalities, and disaster declarations from the southeastern United States to empirically validate each index. We find that disaster indices, though thoughtfully substantiated by literature and theoretically persuasive, are not all created equal. While four of the five indices perform as predicted in explaining damages, only three explain fatalities and only two explain disaster declarations as expected by theory. These results highlight the need for disaster indices to clearly state index objectives and structure underlying metrics to support validation of the results based on these goals. Further, policymakers should use index results carefully when developing regional policy or investing in resilience and vulnerability improvement projects.