Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item EXPLORATION OF THE FOOD WASTE ENVIRONMENT IN THE UNIVERSITY SETTING AND ITS IMPLICATIONS TOWARD A SUSTAINABLE FOOD SYSTEM(2020) Pavone, Lauren; Song, Hee-Jung; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Americans are throwing away an alarmingly high amount of food. As highlighted in this thesis project, a multitude of factors account for why food waste occurs, but also a significant potential exists for food waste reduction. The purpose of this research was to investigate the food waste environment in the university setting to better understand where to focus food waste reduction strategies. The volume of student plate waste was quantified, and the nutritional and environmental value of this plate waste was calculated. Further, a behavioral survey guided by the Theory of Planned Behavior helped to identify the key factors influencing food waste behaviors in this setting. Plate waste was found to be 5%-14% of all food served in the dining hall facility. The top three food groups that were most frequently discarded included starch and added sugars, fruits and vegetables and whole grains. Food waste related behaviors were found to be strongly influenced by having the confidence and skills for proper food management, feeling guilty about throwing food away, and having financial concerns related to food waste. The results of this research suggest that student plate waste is a significant problem with enormous potential for food waste reduction.Item LONG-RANGE SIGNALING AT THE INTESTINAL-NEURAL AXIS PROMOTES ORGANISMAL HEME HOMEOSTASIS IN C. ELEGANS(2014) Sinclair, Jason Wallace; Hamza, Iqbal; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Metazoans synthesize and regulate intracellular heme in a cell autonomous manner although genetic evidence in vertebrates suggests that cell non-autonomous mechanisms may exist at the organismal level. In C. elegans, a heme auxotroph, extraintestinal tissues are intrinsically dependent on the intestine, which acquires dietary heme for sustenance, supporting the concept that intestinal heme status must be coordinated at the systemic level to regulate whole-organism heme homeostasis. Here we show, by conducting a functional genome-wide RNAi screen in an intestinal-restricted heme sensor worm, that an interorgan heme signaling pathway exists and that >30% of the genes identified from the RNAi screen altered heme homeostasis in the intestine even though these genes are not expressed in the intestine. The biological basis for this signaling is underscored by HRG-7, a cathepsin protease-like protein secreted by the intestine and internalized by distally-located neurons. HRG-7 is specifically secreted from the intestine during heme limitation and hrg-7 depletion causes embryonic lethality concomitant with a heme deficiency response. Reciprocally, neuron-to-intestine heme signaling is mediated by the bone morphogenic protein homolog DBL-1, which recapitulates hrg-7 deficiency when depleted. Remarkably, depletion of both genes simultaneously results in markedly enhanced growth and heme deficiency phenotypes, suggesting that bidirectional signaling between the intestine and neurons mediates systemic heme homeostasis. Our results have uncovered an unexpected role for a protease family member in long-range communication between organs at the intestinal-neural axis to regulate systemic heme homeostasis in metazoa. As humans have over thirty cathepsin and cathepsin-like proteases, several of which are secreted, we anticipate that these proteins may play analogous roles in mammalian biology.Item On-Farm Dry Matter Analysis to Improve Feed Delivery Precision on Dairy Farms(2011) French, Karin R.; Kohn, Richard A; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Uncertainty in dairy ration content impacts feed efficiency, milk production, expenses, and environmental losses. When measuring silage by weight, unknown changes in dry matter (DM) may change the total mixed ration. The objective of this study was to measure variation in silage DM on selected farms and evaluate an electronic method of on-farm DM analysis. Of 31 Maryland farms surveyed, 63% reported DM analysis by an on-farm method, 83% by any method including laboratory measurement. Eight producers performed DM analysis daily for 21 days using a Farmex 1210 Electronic Silage Tester (on-farm) and they recorded precipitation; matching samples were analyzed for DM in a laboratory after oven drying ("standard" method, 55°C followed by 100°C) and by using a Farmex 1210 (laboratory). The standard deviation of mean silage DM varied from 0.72% to 3.33% DM, depending on farm. The electronic method compared poorly to standard DM analysis for most farms.Item From China to the US: nutrition, diet and acculturation of Chinese employed in high-tech industries - Results from a web-based survey(2007-08-06) Wang, Chunling; Sahyoun, Nadine; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Due to the fast development of economies in China and the great needs of professionals in the US, the population of highly educated young Chinese professionals working in high-tech industries has grown very fast in both countries. This population was suggested to have risk of consuming high energy and fat diet in both countries. Objectives: This study aimed to investigate the associations of dietary intake with nutrition knowledge, attitude, dietary self-efficacy and acculturation among Chinese working in high-tech industries in China and in the US. Methods: This study was a cross-sectional self-administered online survey. We studied 925 Chinese aged 20-45 years, who worked in high-tech industries and had at least a bachelor degree in four sub-groups: employees of Chinese companies in China; employees of American companies in China; Chinese-born immigrant in the US; and American-born Chinese in the US. A web-based questionnaire including a food frequency questionnaire (FFQ) was developed to assess total energy and fat intakes, nutrition knowledge, attitudes, dietary self-efficacy. Four domains of acculturation were assessed among Chinese in the US. Using these data, we compared the four sub-groups and tested the prediction model of dietary intake and BMI. Results: Our results showed that American-born Chinese participants consumed significantly higher energy and fat than the other three groups. Participants in the US had higher nutrition knowledge, attitude and self- efficacy than participants in China. Chinese-born immigrant men in the US had the highest nutrition knowledge and attitude and the lowest prevalence of overweight among the four study groups of men. The study results suggested that preferring Chinese food and Chinese leisure activity are predictors of lower energy and fat intake in Chinese-born immigrants. Conclusions: The Chinese-born immigrants showed significant advantages in nutrition knowledge, attitude, and dietary self-efficacy and had the lowest prevalence of overweight in men. American-born Chinese consumed the highest energy and fat among the four study groups even though their nutrition knowledge, attitude and self-efficacy were high. Future nutrition promotion programs should make use of these cultural and environmental differences when designing theses programs. The web-based survey method can be utilized in future nutrition research.Item Effects of Aging and Moderate Calorie Restriction on the Reproductive Axis of the Male Rhesus Macaque (Macaca mulatta)(2007-04-25) Sitzmann, Brandon Dale; Ottinger, Mary Ann; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Calorie restriction (CR) has been established as the only non-genetic method of altering longevity and attenuating biological changes associated with aging. This nutritional paradigm has been effective in nematodes, flies, rodents, dogs and possibly non-human primates. Its long history notwithstanding, little is known regarding the exact mechanism(s) of CR action or its potential impact on the hypothalamic-pituitary-gonadal (HPG) axis. The objectives of this project were to: 1) analyze neuroendocrine changes to the HPG axis that occur with aging and 2) evaluate the effects of moderate CR on reproductive function in male rhesus macaques. Pituitary gene expression profiling, semi-quantitative RT-PCR (sqRT-PCR) and immunohistochemistry showed circadian clock mechanism components present in three age categories of macaques, demonstrated age differences in expression for Per2, indicated differential expression of Per2 and Bmal1 at opposing time points and revealed daily rhythmic expression of REV-ERBα protein. These data indicate the ability of the macaque pituitary to express core-clock genes, their protein products, and to do so in a 24-hour rhythm. Young Adult CON and CR pituitary gene expression profiles detected potential differential expression in <150 probesets. A decline in>TSHR and CGA was detected in CR macaques as measured by sqRT-PCR. Other genes investigated showed no diet-induced changes. Young Adult CON and CR testicular gene expression profiles detected potential differential expression in <300 probesets although mRNA expression was not altered based on sqRT-PCR and real-time RT-PCR. Age-related>and/or diet-induced changes in HSD17β3, INSL3, CSNK1E and CGA were observed in a separate experiment with CGA in Old Adult CR subjects returning to youthful levels. Semen samples were collected from Young Adult CON and CR macaques. Normal spermiogram measures, ZP-binding, AR assay and SCSA® were conducted and indicated no differences between CON and CR-treated animals. Both groups exhibited similar daily testosterone profiles with no differences in mean or maximum levels; however, daily minimum testosterone levels were lower in CON animals. It appears that moderate CR had limited impact on neuroendocrine or reproductive function in male rhesus macaques based on our selected endpoints. Thus, advantageous CR health benefits can be achieved without obvious negative consequences to the HPG axis.Item What Does This Question Mean To You? Cognitive Interviewing to Pretest a Questionnaire for Older Adults(2006-08-10) Enagonio, Elisabeth Mary; Sahyoun, Nadine; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Seven cognitive interviews were conducted in adults aged 80 and older to pretest a questionnaire for the Community Connections - Moving Seniors Toward Wellness research project. Respondents participated in intensive one-on-one interviews. The questionnaire was administered, and respondents were probed for comprehension of question content. Older adults with physical limitations answered questions about depression based on physical rather than emotional status, made distinctions between capacity and performance regarding physical function, and failed to understand key medical terms. Wording of questions about personal hardiness was confusing to older adults. The findings were used to simplify wording throughout the questionnaire. Survey designers should be aware that questions about depression may be testing physical rather than emotional status. Questions about physical function should make a distinction between capacity and performance. Common language rather than medical terminology should be used when surveying older adults. Rewritten hardiness questions may be useful in assessing older adults.