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Thesis (Ph.D.)--Virginia Commonwealth University, 2009. / Prepared for: Dept. of Public Policy and Administration. Title from title-page of electronic thesis. Bibliography: leaves 230-254.

Thesis (Ph. D.)--Yale University, 1977. / Includes bibliographical references (p. 210-212).

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis--M. Phil., University of Hong Kong, 1980.

Zugl.: Marburg, Univ., veränd. Diss., 2009

Understanding possible variations in muscle activation patterns and its functional implications to movement control is crucial for rehabilitation. Inter-/intra-subject variability is often observed in muscle activity used for performing the same task in both healthy and impaired individuals. However, the extent to which muscle activation patterns can vary under specific neuromuscular conditions and differ in function are still not well understood. Current musculoskeletal modeling approaches using optimization techniques to identify a unique solution cannot adequately address such questions. Here I developed a novel computational framework using detailed musculoskeletal model to reveal the latitude the nervous system has in selecting muscle activation patterns for a given task regarding neuromechanical constraints. I focused on isometric hindlimb endpoint force generation task relevant to balance behavior in cats. By identifying the explicit bounds on activation of individual muscles defined by biomechanical constraints, I demonstrate ample range of feasible activation patterns that account for experimental variability. By investigating the possible neuromechanical bases of using the same muscle activation pattern across tasks, I demonstrate that demand for generalization can affect the selection of muscle activation pattern. By characterizing the landscape of the solution space with respect to multiple functional properties, I demonstrate a possible trade-off between effort and stability. This framework is a useful tool for understanding principles underlying functional or impaired movements. We may gain valuable insights to developing effective rehabilitation strategies and biologically-inspired control principles for robots.

The water balance equation is one of the most fundamental concepts in hydrology. How much precipitation a river basin receives, and where that water goes, defines what flora, fauna, and industry the basin can support. Models for solving this equation originally relied only on precipitation, air temperature, and day length, but have adapted as new data becomes available. Recent advances in technology, especially remote sensing and web services, make it cheaper and easier than ever to obtain hydrological data, including many variables that were previously impossible to measure. This thesis will examine the water balance of the San Marcos River Basin and demonstrate how remote sensing and web services can improve our understanding of the basin's hydrology. It was found that 72% of precipitation in the San Marcos Basin is lost to evapotranspiration. This percentage varies from year to year as a function of precipitation, but the annual volume of evapotranspiration stays almost constant. It was only during the second consecutive year of drought that there was an appreciable change in evapotranspiration. This suggests that annual evapotranspiration can be thought of as a property inherent to a watershed's hydrology, and so long as there is enough stored water in the soil, that demand will be met. The water left over after ET takes its share can either flow out of the basin through a river channel or stay within the basin as storage. After examining methods for partitioning the available water between outflow and storage, it was found that lumped water balance models cannot be used in the San Marcos River Basin because of its complex interactions with the Edwards Aquifer. In order to better model soil moisture dynamics and groundwater infiltration, a distributed model will have to be developed that accounts for flow in and out of the aquifer. / text

Obesity is a known risk factor for many types of cancer including pancreatic. Calorie restriction (CR), an anti-obesity diet regimen, has potent anticancer effects that may be mediated through its ability to reduce serum metabolic hormones and protumorigenic cytokines such as insulin-like growth factor (IGF)-1. IGF-1 is a metabolic hormone responsive to nutrient status that activates the inflammatory, cancer-related pathway, nuclear factor (NF)-[kappa]B. For this report, we tested the hypothesis that CR, via regulation of IGF-1, inhibits pancreatic tumor cell growth through modulation of NF-kB activation and protumorigenic gene expression. Male athymic nude mice were randomized to either a control diet consumed ad libitum (n=15) or a 30% CR diet (n=15) for 17 weeks, at which time, mice were injected with human pancreatic cancer cells (MiaPaca) and tumor growth was monitored for 6 weeks. Translocation of p65, a regulatory element of NF-[kappa]B, and expression of its downstream gene targets were analyzed in excised tumors. CR mice weighed less, (p<0.05), and had smaller tumors (p=0.022) relative to controls. Tumors from CR mice, relative to controls, demonstrated significant decreases in NF-[kappa]B downstream genes CCND1, RELA, Survivin, VEGF, and XIAP. These findings parallel our previous studies in pancreatic tumors from mouse origin, and suggest that the inhibitory effects of CR on MiaPaca pancreatic tumor growth are associated with decreased NF-kB activation. / text

CAMPO (Capital Area Metropolitan Planning Organization) is undergoing a revision of the regional transportation plan for Central Texas. The key goal of the plan is achieving sustainable development through integrating a multimodal transportation system with dense mixed land use. The CAMPO Plan has incorporated the growth management tool of jobs-housing balance to guide future land use development. To improve jobs-housing proximity and encourage compact growth, the concept of an activity center connected by high capacity transit corridors was employed in the plan, targeting the accommodation of 31 percent of the population and 38 percent of employment in Central Texas by 2035 (CAMPO 2035 Plan 2010). At the time when CAMPO was attempting to define appropriate ratios of jobs-housing balance for the activity centers, critical questions arose: what is a good ratio? Further, how should jobs-housing balance be quantified for guiding land use development? And to what extent could jobs-housing ratio be effectively used as an intervention instrument? This report attempts to provide theoretical and empirical evidence of jobs-housing balance and examine the applicability of jobs-housing balance ratio for different planning purpose in local context. Based on a rich literature review, the report removed the "deceptive simple concept" (Cervero 1991, p. 10) of jobs-housing balance on the surface and gathered insights on jobs-housing balance from existing exemplary studies. Absent a single consensus of a good jobs-housing balance ratio, the goal of this report is to present the possible ways of measuring and defining jobs-housing balance in complex urban development. This report analyzed existing jobs-housing balance of the Austin Region, presenting the truth of commute distance and jobs-housing balance ratio. Local municipalities might consider more factors in terms of the application of jobs-housing balance ratio in local context. / text