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Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 59.

INTRODUCTION: There are two main procedures responsible for correcting refractive error: laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). The most common postoperative complication of all laser vision correction (LVC) surgeries is keratoconjunctivitis sicca, or dry eye. In addition to physical irritation, dry eye can cause poor visual acuity and reduced quality of life. There are inconsistencies in the literature about which procedure results in higher rates of dry eye thus we explored the likelihood of a dry eye intervention within the first year after surgery. METHODS: Performing a retrospective chart review of all patients who underwent LVC procedures between 2009-2019 at a private Boston ophthalmology clinic, we were able to quantify the proportion of patients that required postoperative dry eye interventions within the 12 months following surgery. At this clinic, a dry eye intervention was defined as one of two treatments: punctal plug insertion or prescription medication (Restasis or Xiidra) use. RESULTS: A total of 11,175 LASIK eyes from 5,920 individuals, 1,549 LASEK eyes from 880 individuals, and 2,006 PRK eyes from 1,165 individuals were included in the analysis. Comparing the proportion of LASIK dry eye interventions to the proportion of PRK/LASEK dry eye interventions via a 2-sample z-test at an alpha level of significance of 0.05, yielded a z-value= 5.7 and a p-value= <0.0001 at a 95% CI (0.0102 - 0.0208). CONCLUSION: Our results suggest a greater incidence of postoperative dry eye interventions for PRK/LASEK patients compared to LASIK patients in the 12 months following LVC surgery. This study was limited in regards to both objective and subjective indicators of dryness; therefore future studies should attempt to be more comprehensive in evaluating postoperative dry eye. However, this study should help surgeons in the decision making process of which refractive eye surgery to recommend in order to reduce postoperative dry eye incidence and improve overall patient quality of life and satisfaction. / 2022-06-08T00:00:00Z

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

The continuous effort to understand the complicated behavior of gas hydrates in multiphase flow has led to the evolution of a new paradigm of hydrate blockage. The hydrate community continues to debate the impact of kinetics, agglomeration, and oil chemistry effects on hydrate blockage formation in pipelines and wellbores. However, today’s industry for the most part still continues to rely on thermodynamic means to develop strategies to prevent hydrates altogether in its production systems. These strategies such as thermal insulation of equipment, electric heating, dead oil displacement, and methanol injection add CAPEX, OPEX, and operational complexities to system design. In spite of high oil prices, adopting such strategies to mitigate perceived hydrate blockage risk can end up taxing economics of marginal fields. Developing a comprehensive multiphase flow simulator capable of handling the transient aspects of production operations - shut-in, restart, blowdown and blockage prediction - continues to drive the research in Flow Assurance. New operating strategies based on risk management approach seem to be evolving from the model predictions. A shift in paradigm that allows for operations inside the hydrate region based on sound risk assessment and management principles could be a factor enabling future developments of marginal fields. This paper discusses the challenges and opportunities that have led to the change in focus from prevention of hydrates to prevention of blockage, and describes some initial successes in the development of a first generation empirical tool for the prediction of hydrate blockages in flow lines. Also presented in this article are new experimental data that shed some light on different ways that hydrate blockages can manifest in the field.

Mate choice among males is relatively understudied, despite recent evidence supporting its ubiquity. Theory predicts male mate choice in response to variation in female quality, and male mating strategies that limit polygyny. However empirical research investigating these connections, particularly under natural conditions, is generally lacking. Using the Western black widow spider, Latrodectus hesperus, I investigated male mate choice, male investment, and the advantage of mating with females that differ in their potential to deliver fitness benefits to males via higher fecundity and/or reduced risk of sperm competition. Males were found to be preferentially attracted to larger, high-diet virgin females over females that were smaller due to a lower diet, or having been previously mated, or both. Through a three-year field study on females I found that males likely benefit from selectivity, as smaller, low-diet females often failed to deposit any egg sacs throughout the breeding season, likely due to their shortened web-site tenure and/or lack of bodily resources. I investigated the costs and benefits to male genital breakage in L. hesperus, a strategy typically assumed to result in male sterility while providing paternity protection. I found that genital mutilation in L. hesperus did not cause sterility and that males were capable of inseminating multiple females, likely because of the comparatively low amount of genital damage and the likelihood of the efficient placement of genital fragments. Evidence from double mating trials supported the efficacy of broken genital fragments as plugs, but first male sperm precedence was often maintained in cases where male genital breakage failed or fragments were positioned incorrectly, which occurred frequently. Together, these laboratory and field experiments contribute to a more complete view of mate choice.

Mate choice among males is relatively understudied, despite recent evidence supporting its ubiquity. Theory predicts male mate choice in response to variation in female quality, and male mating strategies that limit polygyny. However empirical research investigating these connections, particularly under natural conditions, is generally lacking. Using the Western black widow spider, Latrodectus hesperus, I investigated male mate choice, male investment, and the advantage of mating with females that differ in their potential to deliver fitness benefits to males via higher fecundity and/or reduced risk of sperm competition. Males were found to be preferentially attracted to larger, high-diet virgin females over females that were smaller due to a lower diet, or having been previously mated, or both. Through a three-year field study on females I found that males likely benefit from selectivity, as smaller, low-diet females often failed to deposit any egg sacs throughout the breeding season, likely due to their shortened web-site tenure and/or lack of bodily resources. I investigated the costs and benefits to male genital breakage in L. hesperus, a strategy typically assumed to result in male sterility while providing paternity protection. I found that genital mutilation in L. hesperus did not cause sterility and that males were capable of inseminating multiple females, likely because of the comparatively low amount of genital damage and the likelihood of the efficient placement of genital fragments. Evidence from double mating trials supported the efficacy of broken genital fragments as plugs, but first male sperm precedence was often maintained in cases where male genital breakage failed or fragments were positioned incorrectly, which occurred frequently. Together, these laboratory and field experiments contribute to a more complete view of mate choice.

Soil surface treatments consisting of gully plugs and contour furrows were constructed as a means of reducing erosion and holding sediment on site. To measure the effectiveness of the gully plugs and furrows, angle iron stakes and profile transects were installed to measure soils loss and accompanying change in the soil profile. The profile transects gave a reliable measure of the change in the height of the soil surface in constructed pits and across contour furrows. Because of the shrinking and swelling of the soil, the change in height of the angle iron stakes was found to be much more than the reduction in soil surface caused by erosion. High intensity thunderstorms, occuring mostly during July, August, and September, cause most of the erosion from the semi-arid land. The gully plugs and contour furrows were effective in holding runoff and sediment on site, but the life expectancy of the treatments is only about fifteen years.

No description available.