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This work seeks to develop a high quality prognostic model for the CARE-HF data; see (Richardson et al. 2007). The CARE-HF trial was a major study into the effects of cardiac resynchronization. Cardiac resynchronization has been shown to reduce mortality in patients suffering heart failure due to electrical problems in the heart. The prognostic model presented in this work was motivated by the question as to which patient characteristics may modify the effect of cardiac resynchronization. This is a question of great importance to clinicians. Efforts are made to produce a high quality prognostic model in part through the application of methods to reduce the risk of over-fitting. One method discussed in this work is the strategy proposed by Frank Harrell Jr. The various aspects of Harrell’s approach are discussed. An attempt is made to extend Harrell’s strategy to frailty models. Key issues such as missing data and imputation, specification of the functional form of the model, and validation are examined in relation to the prognostic model for the CARE-HF data. Material is presented covering survival analysis, maximum likelihood methods, model selection criteria (AIC, BIC), specification of functional form (cubic splines and fractional polynomials) and validation methods (cross-validation, bootstrap methods). The concepts of over-fitting and optimism are examined. The author concludes that whilst Harrell’s strategy is valuable it is still quite possible to produce models that are over-fitted. MDL (Minimum Description Length) is suggested as potentially useful methods by which statistical models can be obtained that have an in built resistance to over-fitting. The author also recommends that concepts such as over-fitting, optimism and model validation are introduced earlier in more elementary courses on statistical modelling.

This thesis describes studies into the effect of season and photoperiod on the aMSH-synthetic activity of the pars intermedia in the highly photoperiodically-responsive Soay sheep. The influence of the hypothalamus and dopaminergic inhibition was also studied. The localisation and expression of POMC mRNA, POMC-derived peptides and both PC1 and PC2 mRNAs and proteins were measured by in situ hybridisation. RNase protection assay and immunocytochemistry; specific riboprobes were developed for the project. The presence of the cellular proliferation marker, PCNA, was used as an index of cellular proliferation. In the first study, the general anatomy of the ovine pituitary gland was investigated using the new methodology. POMC mRNA was highly expressed in melanotrophs in the pars intermedia and in the corticotrophs dispersed in the pars distalis. The POMC-derived peptides, ACTH and aMSH both occurred in the pars intermedia while in the pars distalis ACTH predominated and aMSH was only weakly expressed. PC1 mRNA and protein was also expressed both in the pars distalis and the pars intermedia with a distribution similar to that of POMC, as well as in the pars nervosa. PC2 mRNA was expressed in the pars intermedia while PC2 protein occurred principally in the pars intermedia and pars nervosa. Like aMSH, PC2 protein was expressed weakly in the pars distalis. The second study investigated the changing activity of the pars intermedia at four seasonal time points in the Soay ewes living outdoors and exposed to natural photoperiod (n=5/group). Expression of POMC and PC1 mRNA was significantly greater in the summer and autumn compared to the winter and spring. The autumnal increase in pars intermedia activity was also characterised by an increase in cellular proliferative activity and hypertrophy of melanotrophs.

This doctoral dissertation is an empirical study employing the case study research design and aims at gathering the perspectives of fraternity men concerning the utility of anti-discrimination clauses in protecting minority members' interests and contributing to a sense of belonging. The case includes a mixed methodology of a survey, focus group interviews, document review, and one on one interviews in terms of data collection. The participants in this study are active and alumni fraternity men affiliated with a social fraternity in the North American Interfraternity Conference. The active member sample comes from a single chapter of the organization at a large, research, public institution in the northeastern region of the United States. The alumni were selected based in consultation with the leadership of the organization. The data indicates that the sampled chapter of the organization has a generally welcoming environment to men of different races, religions, and sexual orientations, but that fraternity bylaws and antidiscrimination clauses are not credited by members for this. Instead, a welcoming organizational climate as promoted within the given chapter allows for this appreciation of diversity to continue. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

Sexual minority men experience higher rates of body dissatisfaction (BD) than heterosexual men (Frederick & Essayli, 2016). BD is associated with negative health outcomes in this population, including eating disorders (Yean et al., 2013), depression (Blashill et al., 2016), suicidality (Grunewald, Calzo, et al., 2021), and risky sexual behavior (Goedel et al., 2017). Sexual minority men who use dating apps may be at greater risk of experiencing BD via exposure to appearance-based discrimination (Tran et al., 2020), sexual objectification, and weight stigma (Filice et al., 2019). Little is known about sexual minority men’s experiences of appearance discrimination on dating apps and how they cope with these negative experiences. This experiential qualitative study addressed this gap in the literature using reflexive thematic analysis (Braun & Clarke, 2006; Braun & Clarke, 2022). Fourteen sexual minority men shared their lived experiences with appearance discrimination on dating apps in semi-structured individual interviews. Findings were organized into four categories (context, type, coping strategies, and reflections) that collectively told a compelling story about how sexual minority men experience and cope with appearance discrimination on dating apps. The interviewees noted that appearance discrimination often focused on specific physical attributes like body hair, race and skin tone, and body weight and shape. Appearance discrimination evoked psychological distress and worsened their body image, but men felt that certain contextual factors like intention for dating app use, mental health struggles, and lived experience with minority stressors, influenced their perceptions, experiences, and coping. While some coping strategies (i.e., avoidance) were ultimately unhelpful, other strategies like boundary setting, positive reappraisal, social support seeking, and problem solving, were critical to supporting their psychological well-being and facilitate reflection. Implications for future research, psychotherapy, and community-based intervention are discussed. In particular, clinicians should assist their clients in developing healthy, adaptive ways of coping such as setting firm boundaries, confronting perpetrators, taking breaks from dating apps when needed, and seeking social support. Clinicians should also help SMM clients find healthy and supportive activities within the gay male community that de-emphasize appearance and status.

The authors were perplexed by the seeming dichotomy between the majority 70% of Haitian consumers being chronically food insecure, but still preferring to pay premium international market prices for long-grain rice that constitutes 30% of the calories in this poorest nation in the Western Hemisphere. The aim of this study was to determine the optimal percent broken rice in regards to price specifically to Haiti. Optimization between quality and price point is seen as the best rice for the price, and can be found through combining individual preferences with willingness to pay. Broken rice (brokens) garner a significantly discounted price compared to the whole grains, despite offering very similar, if not the same or better, nutritional quality. Through analyzing rice samples with concurrent surveys from 300 Haitians, we were able to determine that brokens have a relatively small effect on consumer preferences in Haiti. This indicted that less strict import standards on broken percentage of rice could benefit the welfare of Haitians in need of discounted food supply. To supplement these findings, a sensory study in the University of Arkansas Sensory Service Center was conducted with the aim of determining brokens’ impact on rice consumers both pre-purchase and post-cooking. Broken rice is sold at a significant discount worldwide, and this study aimed at understanding why that discount persists and if the discounts perpetuated by producers are aligned with consumers’ willingness to purchase broken rice. Through testing rice-eating consumers’ perception of the same rice samples in their raw and cooked forms with percentage broken being the only independent variable (in incremental percentages of 5%, 10%, 20%, 30%, and 40%), the results showed that the raw rice’s appearance with high levels of brokens is disproportionately affecting the broken rice market

An ultra-wideband radar system is built at the University of Tennessee with the goal to develop a ground penetrating radar (GPR). The radar is required to transmit and receive a very narrow pulse signal in the time domain. The bistatic radar transmits a pulse through an ultrawide spiral antenna and receives the pulse by a similar antenna. Direct sampling is used to improve the performance of the impulse radar allowing up to 1.5 GHz of bandwidth to be used for signal processing and target detection with high resolution. Using direct sampling offers a less complex system design than traditional lower sample rate, super-heterodyne systems using continuous wave or step frequency methods while offering faster results than conventional equivalent time sampling techniques that require multiple data sets and significant post-processing. These two points are particularly important for a system that may be used in the field in potentially dangerous environments. Direct sampling radar systems, while still frequency limited, are continually improving their upper frequencies boundaries due to more power efficient, higher sampling rate analog to digital converters (ADCs) which relates directly to better subsurface resolution for potential target detection.

Tinnitus is the phantom perception of sound without an external acoustic source. Although tinnitus affects 10-15% of adults, with symptoms from mildly bothersome to debilitating, current treatments are limited by an inadequate understanding of its underlying pathophysiology. Improved understanding must address perception at all levels, from a peripheral deficit (e.g. hearing loss), to central auditory plasticity generating the internal signal, to higher-order brain networks governing its conscious awareness. The first study examined top-down mechanisms of attention in modulating tinnitus and potentially its loudness, pitch, or distress. Subjects with and without chronic tinnitus monitored one of two tonal steams, one with similar frequency as tinnitus and the other well-outside this region. Cortical evoked-potentials showed enhanced attentional gain when tinnitus subjects focused to the tinnitus frequency, which related to increased tinnitus loudness. A later enhancement to the non-tinnitus frequency suggested tinnitus also impacts selective processing of other sounds. A discrimination analysis indicated that attention-derived variables could serve as a biomarker to detect tinnitus from control subjects with similar age and hearing. The second study employed psychophysical methods to uncover sensory deficits in tinnitus and improve its diagnosis. Tinnitus subjects showed normal temporal acuity for detecting silent gaps in pure-tones, including those matching the tinnitus pitch. Although gap detection is widely used to assess tinnitus in animal research, assuming tinnitus “fills-in” the gap, the procedure appears ill-suited for clinical diagnosis in humans. Tinnitus subjects also showed normal frequency discrimination. However, slightly improved intensity discrimination of low-level sounds indicated a mechanism of increased auditory gain in the central pathways. Together, these results suggest that “bottom-up” sensory deficits in tinnitus have subtle impacts on basic auditory processing, while top-down attention plays a central role in gating tinnitus perception and may be developed as an objective clinical biomarker.

This doctoral dissertation is an empirical study employing the case study research design and aims at gathering the perspectives of fraternity men concerning the utility of anti-discrimination clauses in protecting minority members’ interests and contributing to a sense of belonging. The case includes a mixed methodology of a survey, focus group interviews, document review, and one on one interviews in terms of data collection. The participants in this study are active and alumni fraternity men affiliated with a social fraternity in the North American Interfraternity Conference. The active member sample comes from a single chapter of the organization at a large, research, public institution in the northeastern region of the United States. The alumni were selected based in consultation with the leadership of the organization. The data indicates that the sampled chapter of the organization has a generally welcoming environment to men of different races, religions, and sexual orientations, but that fraternity bylaws and anti-discrimination clauses are not credited by members for this. Instead, a welcoming organizational climate as promoted within the given chapter allows for this appreciation of diversity to continue.