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The Cape ground squirrel, Xerus inauris, is a highly social cooperative breeder that forms groups containing multiple breeding females. While the distribution of reproduction among group members is fairly even (i.e. exhibits low reproductive skew), previous studies of Cape ground squirrels suggest the reproductive development of sub-adult females is inhibited by the presence of adult breeding female group mates. As reproductive delay is known to be influenced by a number of different parameters, my goal was to determine if other factors affected the timing of sexual maturity, and if so, which factors are the most influential. In this study, I simultaneously test the relative power of seven different social and environmental parameters at explaining the variation in the female age of sexual maturity in two populations of Cape ground squirrels. Field work was conducted at two study sites in southern Africa, where trapping, behavioral and hormonal data were collected to determine the timing of reproductive development. Hormonal data was analyzed through the use of steroid enzyme immunoassay analysis to quantify the concentration of gonadal hormone in fecal samples which indicate the onset of sexual maturity. Prior to the start of the field season, I conducted an initial experiment to determine the best alternative form of fecal storage if freezing was unavailable. I found that drying feces provides a more reliable method for long-term preservation of fecal steroid concentrations when compared to storing fecal samples in alcohol. Data associated with each of the seven parameters was analyzed using model selection to simultaneously measure the ability of different combinations of parameters to explain the observed variation in female age of sexual maturity. I found that an increase in the number of adult breeding female group mates and related adult male group mates resulted in a substantial inhibition of female reproductive maturity. I concluded that a female Cape ground squirrel's age of sexual maturity is principally a result of the interaction between adult breeding females' capacity for reproductive suppression and sub-adults' ability to maximize lifetime reproductive success while minimizing inbreeding. The overall reproductive dynamics of each social group results from the tug-of-war between the adult and sub-adult female group mates to control breeding within the group, with minimal direct influence on sexual maturity by environmental factors.

Stroke is a leading cause of long term disability in the United States. The therapeutic benefits of intravenous thrombolytics is time dependent in an acute ischemic stroke patient and is an important determinant of 90 day and one year functional outcomes. This study investigated areas in the stroke alert process of a community based primary stroke care center that resulted in the delay of administration of thrombolytics within 60 minutes of an acute ischemic stroke patient's arrival to the emergency room. A retrospective descriptive design was utilized and chart reviews were done on 40 patients that received thrombolytics in the emergency room. Patient characteristics and time variables associated with the various steps in the stroke alert process were extracted. Findings showed that only 7.5% of the patients received thrombolytics within the recommended 60 minutes, with the longest time interval associated with time from arrival to the emergency room to time of evaluation by teleneurologist. There were no significant differences in the characteristics of patients who received thrombolytics within 60 minutes and those patients that received thrombolytics after 60 minutes. Recommendations were made for changes in organizational and practice strategies to improve timely administration, and for future research involving the effects of quality improvement initiatives

Background: The specific clinical impact of delays to hemostatic intervention in trauma is under-explored. Objectives: Investigate the current understanding of the impact of increasing time to hemostasis and assess its relationship with clinical outcomes. Methods: We conducted a systematic review to characterize existing definitions of delayed hemostasis and its clinical sequelae. We conducted a cohort study of 147 trauma patients to investigate the impact of increased time to hemostasis. Results: Most studies demonstrated significant relationships between time to hemostasis and mortality, despite heterogeneity. The cohort study failed to demonstrate a significant association between time to hemostasis and mortality. Discussion: The thesis has taken steps to investigate time to hemostasis with appropriate methodology. The findings are limited by sample size and confounding by indication. Conclusions: There remains a substantial gap in the literature with respect to understanding the impact of increasing time to hemostasis in trauma and larger studies are needed.

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