To understand how falls occur during walking in older adults, we need to understand how the nervous system maintains stability, and how aging affects walking. Four studies were conducted to better understand the effect of age on gait. Older adults display higher gait variability compared to young adults, possibly because of their slower walking. We compared gait stability at multiple controlled walking speeds. Greater gait variability in healthy elderly existed independent of slower walking. Their diminished strength and flexibility partly explained this difference. To explain slower walking in the elderly, some have suggested that muscle weakness and stiffness may force people to walk slower. Others have suggested that people choose to walk slower to be more stable. We compared dynamic stability of gait at multiple speeds. Healthy older adults also exhibited more stability at slower speeds, yet walked at speeds comparable to young adults despite the lower strength and flexibility. Therefore, weakness and stiffness may not force healthy older adults to walk slower. The goal of the nervous system during walking may be to maintain stability of superior segments. We tested whether superior segments are more stable than inferior segments during walking. Superior segments exhibited less orbital stability during preferred walking speed, in contrast to previous suggestions. This highlighted the importance of trunk control during gait. The effects of aging on the fluctuations in the muscle activity during gait are not well understood. We quantified the stride-to-stride fluctuations of EMG as a measure of muscle activation patterns in state-space. Variability increased with speed except in the gastrocnemius. Orbital stability was less in older adults, suggesting that deviations in the EMG amplitude pattern were not readily corrected. Less local stability was seen in older adults, suggesting that older adults were more sensitive to perturbations. Together, these findings suggest that trunk control is important during gait. Strength and flexibility deficits help explain higher variability and lower stability in older adults. Future work will need to address the effect of strength interventions, neurophysiological decline on gait stability and fall risk.

During the Medieval period of Denmark, economic and trade relations grew inter-regionally, with culture, ideas, and products being transferred on a more regular basis through the 11th to 13th centuries. Beginning around 1050 AD and lasting until AD 1536, the country faced drastic climatic changes, shifting economic and agricultural practices, and disease outbreaks (most notably the bubonic plague). The current study seeks to investigate mobility during this period from two medieval cemeteries around Horsens, Denmark: the rural site of Sejet and the urban site of Ole Wormsgade, both used throughout the 12th to 16th centuries. A previous isotopic analysis using oxygen indicated that some movement was seen at these sites, with three individuals identified as potential migrants from other Scandinavian regions. This study compares the existing oxygen isotopic data with variations in 87Sr/86Sr ratios from these samples. Such ratios represent local bedrock baselines of strontium, which are slightly different between eastern and western Denmark. ICP-MS was used to measure 87Sr/86Sr ratios, and results are interpreted in the context of climatic changes and shifting socioeconomic practices. The results suggest that longer-distance movements into Denmark were seen during the Early Medieval Period. The potential migrant identified in this research points to movement towards the rural population at Sejet, and could possibly connect this migration with marriage rules influencing immigration at the time. This research demonstrates that movement during the medieval period of Denmark was a complex, dynamic, and multilinear process during a time of increasing urbanization. / October 2015

The exit/entry patterns of students in higher education have been a matter of concern to college administrators and counselors for over half a century. The purpose of this study was to identify certain characteristics commonly associated with persistence in order to determine if these same characteristics are likewise predictive of success in teacher training programs. The data base was the National Longitudinal Study of the High School Class of 1972. This study was an investigation designed to observe the educational and vocational activities, plans, aspirations, and attitudes of high school seniors of that year and subsequent years through three follow-up studies. The sample design was a two-strage probability sample with schools as the first stage and students as the second stage. The sample was highly stratified with variables such as type of control, geographical region, minority group enrollment, and level of urbanization making up the strata. The base year questionnaire was administered in the spring of 1972 and consisted of 104 questions. Subsequent follow-ups in 1973, 1974, and 1976 asked questions similar to those asked int he base year and others necessary to ensure continuity of data. The sample used for the present study consisted of 472 prospective teachers. Identifying education as a major and aspiring to teach was the method used to determine sample members. Additional criteria were used to select migratory and non-migratory prospective teacher sub-groups. The sub-groups identified were persisters, drop-ins, drop-outs, late entries, program transfers, and college transfers. Since most students move into migratory patterns due to one or more intellectual or non-intellectual reasons, the present study was designed to compare certain selected factors hypothesized to have a relationship with this movement. Ability, satisfaction with the college environment, values, and self-concept were factors chosen for this comparison. Ability was determined in the base year from standardized tests such as the Scholastic Achievement Test. The students' feelings toward their instruction, social life, campus resources, and curriculum were used as a measure of satisfaction. Having lots of money, being a leader in the community, living close to parents, and correcting social ills were used to determine values. Self-attitude, self-worth, external satisfaction, and internal satisfaction were factors selected to measure self-concept. Levels of satisfaction, values, and self-concept were collected in all three follow-up studies. Ability was determined only in the base year. The design of the investigation was to compare the only nonmigratory group, persisters, with other prospective teacher sub-groups considered migratory. Comparisons were made using the persistence characteristics identified earlier, namely, ability, satisfaction, values, and self-concept. Additional comparisons were made between prospective teacher sub-groups on the basis of race, sex, and type of institutionalized control. Longitudinal trends were incorporated into these comparisons. Prospective teacher sub-groups were also examined in relation to financial assistance. The results suggest that ability and satisfaction measures can provide a persistence index that permits differentiation between certain prospective teacher groups. There is a further indication that ability tests provide a clear distinction between minority and non-minority prospective teachers. Ability and certain self-concept and satisfaction measures provide a distinction between males and females in teacher training programs. Differences among private and public college prospective teachers can be seen with selected achievement tests. Public college late entries and drop-outs are more dissatisfied with the college environment than any other prospective teacher group. Finally, a relationship exists between the amount of financial assistance and the various prospective teacher sub-groups. This relationship is most pronounced for late entry students.

Drawing from medical anthropology's approach to global health, this dissertation examines well-being among HIV- and TB-infected labor migrants in South Africa. Based on forty-four months of fieldwork from 2005 to 2013, it narrates households' struggles to make ends meet materially and morally in a context of unemployment, scarcity, and epidemic. / Anthropology

This dissertation offers an ethnography of motorcycle taxi drivers: Bangkok's most important and informal network of everyday mobility. Drawing on over eight years of experience in the region, six months of archival research, and 24 months of fieldwork, I analyze how the drivers, mostly male rural migrants, negotiate their presence in the city through spatial expertise, bodily practices, and social relations. Their physical mobility through traffic, I argue, shapes their ability to find unexplored routes in the social, economic, and political landscapes of the city and to create paths for action where other urban dwellers see a traffic jam or a political gridlock. My narrative builds up to the role of these drivers in the Red Shirt protests that culminated in May 2010 and analyzes how their practices as transportation and delivery providers shape their role in political uprisings and urban guerilla confrontations. My main finding is that when the everyday life of the city breaks down the drivers take advantage of their position in urban circuits of exchange to emerge as central political actors in contemporary Bangkok by blocking, slowing down, or filtering the circulation of people, goods, and information which they normally facilitate. Owners of the Map proposes an alternative view of contemporary urbanism in which the city is constructed day after day through the work of connection and mediation, its frictions and failures, the tactics adopted to resist them, as well as the political tensions that emerge from these struggles. / Anthropology

This dissertation builds a socio-cultural biography of Paris's Gare du Nord, Europe's largest railway station, from its transnational aims to connect Europe in the nineteenth century, to early twentieth century strikes, to twenty-first century immigration and riots. It shows how the formation of subjects, boundaries, and the "dangerous classes" in France were linked to infrastructural development. Through this examination, I argue that official French rhetoric and policies around the so-called "dangerous classes" created ideologies of contact that played out in concrete public space and came to be challenged by subjects and groups represented as dangerously different. Through encounter, overlapping boundaries--beyond the foreigner/citizen divide--became significant in the Gare du Nord, as marginalized subjects created new ways of relating spaces and bodies in this heterogeneous arena. My dissertation examines the connection between four processes that govern the station’s socio-political trajectory: 1) the government’s elaboration of the "dangerous classes" paradigm that led to expanding technologies of policing and surveillance; 2) the development of transportation infrastructure that brought migrants and goods to the capital; 3) the emergence of a railroad labor economy that created a new class of workers; and 4) the arrival and settling of immigrant groups from former colonies. I show how "dangerous" social archetypes, from the nineteenth century provincial migrant, to the early twentieth century railway worker on strike, to the African-Muslim immigrant, were summoned and reconfigured in events at the Gare du Nord and shaped the future configuration of political subjects and their struggles. I focus ethnographically on the trajectories of African immigrants at the station, the contemporary "dangerous classes." I argue that through their trans-regional networks and practices, the Gare du Nord has become a unique site of political contestation as it transforms into a node that connects the station to immigration pathways through sub-Saharan and North Africa. By offering an ethnographic approach to multidisciplinary conversations on transnational cities and postcolonial history, my dissertation builds a framework and methodology to analyze proliferating "theaters of encounter:" sites suffused with conflicting idioms, grounded in structures of human and capital circulation, and traversed by histories of struggle.

The current study evaluated a multiple-membership growth curve model that can be used to model growth in student achievement, in the presence of student mobility. The purpose of the study was to investigate the impact of ignoring multiple school membership when modeling student achievement across time. Part one of the study consisted of an analysis of real longitudinal student achievement data. This real data analysis compared parameter estimates, standard error estimates, and model-fit statistics obtained from a growth curve model that ignores multiple membership, to those obtained from a growth model that accounts for multiple school membership via the MMREM approach. Part two of the study consisted of a simulation study designed to determine the impact of ignoring multiple membership and the accuracy of parameter estimates obtained under the two modeling approaches, under a series of data conditions. The goal of the study was to assess the importance of incorporating a more flexible MMREM approach when modeling students’ academic achievement across time. Overall, the results of the current study indicated that the Cross-classified multiple membership growth curve model (CCMM-GCM) may provide more accurate parameter estimates than competing approaches for a number of data conditions. Both modeling approaches, however, yielded substantially biased estimates of parameters for some experimental conditions. Overall, results demonstrate that incorporating student mobility into achievement growth modeling can result in more accurate estimates of schools effects. / text

Decision makers often present military researchers with a most daunting challenge: to pursue, with some level of prophetic certainty, innovative concepts that will yield increased capabilities during future wars against forecasted threats in not-yet- determined locations. This conundrum is complicated further with the requirement that the proposed technology yield benefit throughout the various strata of military operations. In the maturation of an advanced capability enabled by a technological advancement, a groundbreaking design should simultaneously demonstrate performance overmatch against an envisioned foe while showing that the costs associated with development, procurement, and operation outweigh reverting to an incremental advancement in the conventional means of delivering combat power. This manuscript focuses on the construction and utilization of decision support tools for use by scientists and engineers charged with providing a quantitative evaluation of an advanced ground combat system. The concepts presented focus on the effects and synergy regarding the combat vehicle principal attributes of survivability, lethality, and mobility. Additionally, this study provides a framework for analysis of these attributes when screened at the tactical, operational, and strategic levels of war. These concepts are presented and demonstrated from both the candidate selection (or choice) perspective, and the concept development (or design) perspective. As an example of this approach, this study includes a comparison of conventional powder gun cannonry versus a specific type of electromagnetic launch device known as the railgun. The decision support tools formulated in this dissertation allow the user to distill, at a coarse level of fidelity, the parametric relationships between system survivability, lethality, and mobility for advanced weapon system concepts. The proposed methods are suited for evaluation at the nascent stages of development, when the information normally applied in standard methods is sparse. This general approach may also be valuable in contemporary acquisition strategies employed in urgent fielding efforts, where the immediacy of the problem can benefit from an expedient and efficient method of analyzing the coupled and synergistic effects of implementing a proposed technology. While advantage is typically measured in terms of performance overmatch at the platform level, the broadening of this consideration vertically to higher levels of military command can aid in identifying the competing issues and complementary relationships related to a technical approach. Finally, given the backdrop demonstration for the framework, this manuscript may serve as a brief summary of system fundamentals and design theory for direct fire powder gun cannonry and electromagnetic railguns. / text

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Sociology / Master / Master of Philosophy