Theses and Dissertations from UMD
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Item DIET, FOOD SECURITY, SOCIAL RELATIONSHIPS AND DEPRESSIVE SYMPTOMS IN HOMEBOUND OLDER ADULTS IN THE UNITED STATES AND THEIR IMPACT ON HEALTHCARE UTILIZATION(2020) Ashour, Fayrouz A.; Sahyoun, Nadine R; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Homebound older adults may be at increased risk for malnutrition and social isolation, posing a potential threat to them aging in their communities and increasing healthcare cost. The Nutrition Service Program under Older Americans Act (OAANSP) was established to support older adults aging in place by delivering meals and providing nutrition-related services. Aims: 1) Examine diet quality of home-delivered meal (HDM) recipients; 2) examine direct and indirect associations between social relationships, depressive symptoms, food insecurity (FI) and diet quality; and 3) examine direct and indirect associations between social relationships, FI, diet quality and hospitalization. Methods: Data obtained from OAANSP Outcomes Evaluation study included: 1) client outcomes survey, 2) two 24-hour dietary recalls, and 3) Medicare healthcare utilization data. Dietary recalls examined diet quality by calculating 1) population-level mean HEI scores; and 2) usual vegetable and protein intakes. Diet quantity was compared to Dietary Guidelines for Americans 2010 (DGA), and structural equation modeling was used to examine direct and indirect relationships. Results: HDM recipients and controls have high prevalence of FI, 22.4% and 16.5%, respectively. HDM recipients who did not receive a meal on day of dietary recall (no-meal recipients) had significantly poorer diet quality than HDM recipients who received a meal (meal recipients) that day and control group. Quality of overall diet for meal recipients, no-meal recipients and controls did not meet recommendations for several food groups/nutrients. Compared to DGA, HDM and complementary foods were low in whole grains, dairy, fiber, and surpassed upper limit of consumption for saturated fats, refined grains, sodium and added sugar. High FI was associated with greater depressive symptoms and lower usual vegetable intake in control group. High FI was associated with lower usual protein intake in HDM recipients and controls. Both groups were at high risk for protein insufficiency, which was associated with greater hospitalization in the control group. Conclusions: HDM recipients and controls have high prevalence of FI, poor diet quality, and insufficient protein intake. Increasing funding for OAANSP can allow program expansion and improvement of HDM. Validated tools to examine social relationships and additional contributors to FI are neededItem ENVIRONMENTAL IMPACTS OF CHANING DIETARY QUALITY(2018) He, Pan; Baiocchi, Giovanni; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The food sector has been recognized as a significant contributor to multiple environmental issues including GHG emissions, water shortage and contamination, ecological disruption, etc., while the malnutrition issues has been increasingly affecting global public health over the years, especially in developing countries such as China where the diet patterns have been shifting considerably over the decades. To develop a sustainable diet that can minimize the environmental impact while meeting nutritional quality targets within economic affordability and cultural acceptability, knowledge is required on how these aspects are interconnected via dietary patterns not only for different countries but also across heterogeneous subnational socio-economic status. The overall aim of this research is to quantitatively evaluate the environmental impacts and nutritional quality of different dietary patterns characterized by socio-economic status. With this overarching question, this study explores three specific research questions that address the historical and assumed dietary patterns at different scales: 1) How have the environmental impact of the Chinese dietary patterns changed with the human nutritional quality for different socio-economic groups over the years? 2) How would an improvement in nutrition quality change the dietary environmental footprints in China? 3) How would the global adoption of healthy diets affect the environmental impacts in each country caused by agricultural production? This dissertation is a synthesized analysis combining the environmental impact accounting and dietary quality evaluation. It links individual food consumption records with environmental impact factors and dietary recommendations to quantitatively analyze the nutrition-environmental nexus for individuals from different income groups, living areas, and countries, and compare how such nexus differ by these socio-economic features. In this way, this dissertation identifies opportunities and challenges in achieving a “win-win” solution for protecting the natural environment and improving public health jointly for individuals from various socio-economic contexts. Its findings provide implications for goal setting and cost-benefit analysis of integrative policymaking concerning joint nutrition development and environmental management.Item Phylogenomics, Systematics, and Evolution within the Nudibranch Group Cladobranchia (Mollusca: Gastropoda)(2017) Goodheart, Jessica Ann Marie; Cummings, Michael P; Collins, Allen G; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)To truly understand evolution, we must document patterns of variation in traits – ranging from anatomical features of individuals to geographic ranges of species – to gain insights into the mechanisms that lead to changes in diversity through time. This type of work requires a robust historical context of evolutionary relationships in order to make comparisons across taxa and inferences about past events. My dissertation provides a thorough phylogenetic analysis of the marine gastropod group Cladobranchia (Mollusca) to better understand the evolution of defensive capabilities within the clade. In the absence of a protective shell, lineages within Cladobranchia have evolved a diverse array of alternative defense mechanisms, including the use of stinging organelles (nematocysts) acquired from their cnidarian prey. It has been hypothesized that incorporation of nematocysts as a defensive strategy may have been an evolutionarily important event that led to large-scale diversification within this group. As such, understanding the steps involved in the evolution of this ability is necessary for evaluating this hypothesis. A major objective for my dissertation has been to use transcriptome (RNA-Seq) data from 37 species in Cladobranchia in order to generate a well-supported phylogenetic hypothesis of Cladobranchia. This research has produced the most highly supported phylogenetic tree of Cladobranchia thus far and contributes to confidence in the efficacy of genomic data to resolve relationships among gastropod lineages. As I have been able to expand this phylogenetic hypothesis with additional taxon sampling, including molecular data from a further 60 species, I have been able to provide context for understanding the evolutionary steps that led to the ability to sequester nematocysts. This phylogeny was then combined with morphological data from 50 nematocyst sequestering species within Cladobranchia to allow for a more detailed reconstruction of the evolution of nematocyst sequestration and prey preference within this clade. Overall, this work builds knowledge of the relationships among major lineages within Cladobranchia, and has substantially increased understanding of the evolution of morphological and ecological characters in this group.Item Electronic Interventions to Improve Health Behaviors in College Students(2014) Schweitzer, Amy; Lei, David K.Y.; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Introduction: In transitioning from adolescence to adulthood, college students are faced with significant challenges to their health habits. Time, independence and stress have been known to result in poor eating and exercise habits which can lead to increased disease risk. Objective: To assess whether an electronic health intervention can improve health habits in college students. Methods: A 24-week diet and physical activity program was delivered by e-mail to 148 college students. The intervention involved weekly tailored, interactive diet and physical activity goals. The control group received non-diet-non-exercise-related health fact sheets. Baseline, 12-week, and 24-week diet and physical activity surveys were completed online. BMI, neck circumference, waist circumference, and percent fat mass (FM%) by bioelectrical impedance analysis were measured at baseline, week 12 and week 24. Results: Students were 18-20 years old 70% female from a diverse college campus (46% Caucasian, 23% Asian, 20% African American, 5% Hispanic, and 6% other). At baseline, 23% were overweight/obese by BMI, 88% reported consuming <5 fruits and vegetables daily, 59% consumed >10% of kcalories from saturated fat, although 91% met or exceeded 150 minutes/week of moderate-vigorous exercise. Seventy-one percent of students completed all study visits. Repeated measures ANOVA showed a significant treatment by linear time interaction for saturated fat. A significant change from baseline saturated fat intake was detected between the treatment groups at week 24 (mean change ± standard error 0.7±0.42% of kcal for control and -0.3±0.30% of kcal for intervention). Differences in saturated fat intake between the two treatment groups were more evident in those whose intake exceeded recommendations. BMI, neck circumference, waist circumference, FM%, weekly minutes of moderate and vigorous physical activity as well as intake of fruit, vegetables, and added sugar were not significantly different between treatment groups. Conclusion: College students enrolled in an interactive electronic health intervention decreased saturated fat intake compared to control. Furthermore, the decrease observed in the intervention group was mainly due to those whose intake of saturated fat intake was above the recommended 10% of total kcalories. Further development of the electronic intervention program is needed to maximize health benefits in college students.Item Relationships Between Health Behaviors, Perceived Health Status, and Cardiovascular Disease Risk Factors in Adolescent Girls(2008) Goldsholl, Stacy Danielle; Young, Deborah R; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Poor physical fitness and diet contribute to increases in cardiovascular disease (CVD) risk factors including BMI, waist circumference (WC), systolic and diastolic blood pressure (SBP and DBP), and HDL-C levels. These behaviors are also associated with positive perceptions of health status. It was hypothesized that the associations between positive health behaviors and CVD risk factors would be mediated by perceived health status in adolescent girls. Regression models were used to test for independent effects and mediation. 185 girls were analyzed, 83% were African American and 50% were overweight. Perceived health status predicted WC, BMI, and SBP. Fat consumption predicted WC and SBP. There were no associations between health behaviors and perceived health status. Adolescent girls are able to accurately assess their overall health status regardless of fitness or dietary behaviors. Interventions should encourage girls to consider these healthy behaviors when assessing health status to increase participation in these behaviors.Item Dietary Patterns, Metabolic Risk and Survival in Older Adults(2008-10-28) Anderson, Amy Louise; Sahyoun, Nadine R.; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Recent evidence suggests that older adults' diets can appreciably impact their health. Dietary patterns may better capture the multifaceted effects of diet on health than individual nutrients or foods. Objectives: The purpose of this study was to identify the dietary patterns of a cohort of older adults, and examine relationships with body composition, insulin sensitivity, systemic inflammation, and survival. The influence of a polymorphism in the peroxisome proliferator-activated receptor-γ (PPAR-γ) gene was considered. Design: The Health, Aging and Body Composition (Health ABC) Study is a prospective cohort study of 3075 older adults. Participants' body composition, genetic variation, glucose metabolism, systemic inflammation, and vital status were evaluated in detail. Food intake was assessed with a modified Block food frequency questionnaire (FFQ), and dietary patterns were derived by cluster analysis. Results: Six clusters were identified, including a 'Healthy foods' cluster characterized by higher intake of lowfat dairy products, fruit, whole grains, poultry, fish and vegetables. An interaction was found between dietary pattern and PPAR-γ Pro12Ala genotype in relation to body composition. While Pro homozygotes in the 'Healthy foods' cluster did not differ significantly in body composition from those in other clusters, men with the Ala allele in the 'Healthy foods' cluster had significantly lower adiposity than those in other clusters. The 'Healthy foods' cluster had lower fasting insulin and HOMA-IR values than the 'High-fat dairy products' and 'Breakfast cereal' clusters, while no differences were found in fasting or 2-hour glucose. With respect to inflammation, the 'Healthy foods' cluster had lower levels of IL-6 than the 'High-fat dairy products' and 'Sweets and desserts' clusters, and did not differ in CRP or TNF-α. The 'Healthy foods' cluster also had a lower risk of mortality than the 'High-fat dairy products' and 'Sweets and desserts' clusters, and more years of healthy life and more optimal nutritional status than the other clusters. Conclusion: A dietary pattern consistent with current guidelines to consume relatively high amounts of vegetables, fruit, whole grains, poultry, fish and lowfat dairy products may reduce the metabolic risk and improve the nutritional status, quality of life and survival of older adults.Item A carbon and nitrogen isotopic analysis of Pleistocene food webs in North America: implications for paleoecology and extinction(2008-05-05) France, Christine Ann Missell; Kaufman, Alan J; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Carbon and nitrogen isotopic reconstructions of North American Pleistocene trophic relationships were used to examine the extinction within terrestrial mammals ~10,000 years ago and distinguish between two potential causal mechanisms - human over-hunting and climate change. Additionally, individual animals were examined for unique isotopic signatures associated with feeding specializations, digestive strategies, and juveniles. Bones representing a comprehensive set of Pleistocene mammalian genera were obtained from three fossil localities: McKittrick Brea, California; Saltville, Virginia; and several sites in Florida. Collagen, a durable bone protein whose carbon and nitrogen isotopic composition reflects dietary input, was extracted from specimens and analyzed for delta-13C, delta-15N, % collagen, %C, %N, and C:N. Radiocarbon dating and amino acid analyses were performed on select sample sets. Results indicated that several specimens contained well preserved collagen, the isotopic values of which indicated both trophic position and vegetation preference. Those samples that contained residual diagenetic proteinaceous material exhibited increased hydrolysis of collagen with time and leaching of disassociated amino acids. Trophic relationships were reconstructed from well preserved specimens for Aucilla River, Florida and the herbivores of Saltville, Virginia, with a less complete reconstruction established for McKittrick Brea, California. The following notable trends emerged: 1) absence of nitrogen isotopic distinction between ruminants and non-ruminants, 2) enriched juvenile nitrogen isotopic signature, 3) distinction of giant ground sloths as omnivores, 4) C4 grass grazers and open C4 grasslands restricted to southern North American latitudes, 5) generalized and opportunistic feeding habits of herbivores, 6) potential prey specializations of carnivores. A noticeable lack of competition and feeding specialists among herbivores suggested a stable base to these late Pleistocene ecosystems, which argues against climatically induced stress on plants. While carnivore specimens were fewer, the apex trophic levels appeared to exhibit a similar lack of competition, which would be expected in a human-driven extinction where carnivores were stressed due to rapidly over-hunted herbivores. The ultimate cause of the late Pleistocene mammalian extinction in North America can not be exclusively attributed to either of these two mechanisms at this point in time; rather, a combination of factors should be considered.Item Effects of Diet and Weight Gain on Subcutaneous Body Fat Accretion Patterns and Adipocytokine Production in Thoroughbred Geldings(2007-05-08) Suagee, Jessica K; Burk, Amy O; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Fifteen Thoroughbred geldings on an eight month weight gain study were used to evaluate 1) the effects of weight gain and diet on body area (neck, withers, shoulders, ribs, loin, tailhead) condition scores, and 2) the effects of weight gain, diet, and exercise on serum concentrations of tumor necrosis factor-α. The body condition scoring system developed in Quarter horse was slightly modified for use Thoroughbred geldings and involved developing prediction equations that utilized a smaller subset of the body areas. Horses at a BCS of 4 were found to be at a higher risk of inflammation that horses at a BCS of 7. The degree of inflammation was similar between horses fed either a high starch and sugar diet or high fiber and fat diet, indicated by similar TNF concentrations. Restricting daily exercise for two weeks was associated with increased inflammation.Item Ecology of Juvenile Bluefish, Pomatomus saltatrix, in Maryland Coastal Waters and Chesapeake Bay(2005-12-12) Callihan, Jody; Secor, David; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Shallow coastal ocean environments may function as important nursery habitats for juvenile bluefish, yet little ecological research has been conducted in ocean habitats. This thesis examines seasonal production, growth rates, and diet composition of juveniles in Maryland's coastal ocean environment and the Chesapeake Bay estuary. Summer-spawned juveniles dominated in ocean habitats and exhibited rapid growth rates, 2.0 - 2.4 mm d-1, which were likely fueled by an abundant forage base of young-of-the-year bay anchovy present in ocean environments during late summer/early fall. This summer cohort was rare in the Chesapeake Bay, where spring-spawned juveniles dominated. These results suggest ocean habitats provide principal nurseries for summer-spawned bluefish, and that the Chesapeake Bay and other estuaries are principal nurseries for spring-spawned juveniles. Accordingly, year class strength is likely shaped by contributions of juveniles from both oceanic and estuarine nursery habitats.