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
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Item BIOLOGICAL AND FUNCTIONAL CHANGES IN SUPRASPINATUS MUSCLE AFTER ROTATOR CUFF TEAR(2017) Valencia, Ana Patricia; Spangenburg, Espen E; Hagberg, James M; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Rotator cuff (RTC) tears impair upper limb mobility and affect 20% of the adult population. Unfortunately, surgical repair of major RTC tears often fails to restore shoulder function and has a high risk of re-tear. RTC tears induce irreversible, degenerative changes to the muscle that may hinder the recovery of shoulder function. Currently, very few studies have comprehensively assessed RTC muscle function, thus, little is known about which markers may be able predict changes in function after RTC tear. In this dissertation, I present three studies designed to systemically determine the impact of a RTC tear on contractile function of the supraspinatus (SS), the muscle most commonly affected in the RTC. In study #1 I developed a novel method to test in vivo SS contractile function using animal species common to RTC research. In study #2, I found that the SS exhibited a 30% loss in force prior to onset of muscle atrophy after acute RTC tear using the rat model. The initial loss of force was associated with a decrease in the size and continuity of the neuromuscular junction (NMJ). The SS muscle was also more susceptible to injury, which was associated with a reduction in collagen packing density. Therefore, SS size is not the strongest predictor of force output with acute RTC tears. In addition, the increased susceptibility to injury could compound the dysfunction already apparent in the SS muscle after RTC tear. In study #3, I found that the rabbit model experienced a 40% loss of force after 6 weeks of RTC tear that persisted at 12 weeks. Using a number of different in vivo and ex vivo imaging approaches I found the degree of fatty infiltration (FI) to be the strongest predictor of muscle force production after RTC tear. Surprisingly, the data suggested that muscle atrophy only explained the loss in force in torn muscles when little to no FI was present. Therefore, FI is a prognostic marker for muscle weakness after RTC tear, and can help clinicians predict the force generating capacity of the SS for surgery and rehabilitation decision-making. Results from both studies found that SS contractile function was significantly impaired after RTC tear, and identified measureable markers beyond muscle atrophy that were associated with the loss in muscle force that may act as potential therapeutic targets to improve functional outcomes after RTC tear.Item Effects of a Simulated Dicamba Misapplication on Non-tolerant Soybeans (Glycine max)(2015) Morris, Matthew; Ritter, Ronald L; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Approval is pending for the registration of dicamba tolerant (DT) soybeans [Glycine max (L.) Merr.]. The use of dicamba on DT soybeans and other DT crops will increase. Risks associated with dicamba applications include off-target movement to sensitive crops. The objective of this study was to evaluate misapplication of dicamba on non-DT soybeans. Greenhouse and field studies examined a rate titration (0.004 to 0.5 lb ai a-1) of dicamba on non-DT soybeans (V3 stage - three trifoliates). Field studies also examined dicamba application to various growth stages (PRE- preemergence to R5- early pod fill) of non-DT soybeans. Results from the greenhouse and field studies showed that as the rate of dicamba increased, the level of injury to vegetative and yield components also increased. Soybean growth stage at time of application influenced the amount of injury. Less injury was observed when dicamba was applied at the PRE growth stage.Item Elements of Employment Related Disclosure of Disability after Brain Injury(2012) Burnhill, David Asher; Fabian, Ellen; Counseling and Personnel Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Few studies have examined the elements of disclosing a disability in the workplace. Those few studies had a primary focus on reasonable accommodations (RA) where the disclosure process was either secondary or tertiary to the study. Further, there have been no studies to date which have examined elements of disclosure for individuals with brain injury (BI). Disclosure of disability is a crucial first step in the request process for a reasonable accommodation in the workplace and is required by the ADA for individuals requesting job related accommodations. This study examined the (a) experiences of work-related disability disclosure for individuals with BI, (b) the injury, demographic and other factors associated with the decision to disclose a disability at work, and (c) employment-related outcomes associated with disclosure. The primary goal of the current study is to describe the population of people with brain injury who disclose their disability in the workplace and to make inferences about the contributing factors involved in the disclosure process. The study used a cross-sectional survey methods research design. The study consisted of 200 individuals recruited from an online survey hosted on the Brain Injury Association of America's website. Of these participants, 144 (74.6%) disclosed their disability on at least one job and 91 (45%) were currently working. Level of education (X2 =11.945, 3, p=.008), self-efficacy score (F=7.52; p=.007) and time between injury and current age (F=4.56; p=.034) were significantly related to disclosure. Logistic regression analyses were used to examine the combined effects of several predictor variables with disclosure. In this analysis, only time since injury and self-efficacy (SE) scores were significant, where higher SE scores increased the odds of disclosure, and time since injury decreases the odds of disclosure (the more recent the injury, the more likely the individual was to disclose).