Master of Science

thesisResearch has shown that individuals who belong to a marginalized group and who perceive discrimination based on that group membership suffer from a variety of poor health outcomes. However, many individuals belong to more than one marginalized group, and much less is known about the influence of multiple forms of discrimination on health outcomes. Several competing theoretical frameworks describe how multiple forms of stress might combine to affect health, and each of these theories has the potential to inform the literature on discrimination in multiple minority individuals. First, multiple stressors can influence health in an additive way: each additional stressor predicts health above and beyond previous stressors. Second is the prominence model: while one form of discrimination is independently damaging with regard to health, the combination of two or more forms is not significantly worse than the effects of just one. Finally, multiple stressors could also interact such that each successive stressor exacerbates or multiplies the effects of previous stressors. The current study examined the influence of multiple forms of discrimination in a population of African American lesbian, gay, or bisexual (LGB) adolescents. The primary aim of this study was to test each of the three models described above to determine which best describes how racist and antigay discrimination combine to predict depression, suicidal ideation, and substances use in a sample of African American LGB adolescents. Participants were included in this analysis if they identified their ethnicity as either African American (n=156) or African American mixed (n=120). Mean age was 17.45 (SD=1.36). Perceived racist and antigay discrimination were each associated with depression and suicidal ideation. However, racist discrimination was prominent in the prediction of examined substance use outcomes, including binge drinking and recent marijuana use. Results reveal that both forms of mistreatment have important associations with depression and suicidal ideation among LGB African American adolescents. Racism was more strongly associated with substance use. Future intervention efforts should be targeted towards reducing discrimination and improving the social context of multiple minority adolescents

Doctor of Philosophy

dissertationYoung men who have sex with men (YMSM) are at disproportionate risk for HIV infection. Parent adolescent communication about sex, particularly mother-adolescent communication, has a protective influence on adolescent sexual risk behavior. However, it is unclear whether these findings generalize to YMSM. The current study used the theory of planned behavior as a framework to examine how parent adolescent communication about condoms is associated with determinants of condom use behavior among YMSM. A measure of parent adolescent communication about condoms among YMSM was developed based on qualitative data. Five hundred and forty-three YMSM ages 14 - 18 (M=16.60) who were "out" to at least one parent completed an online cross-sectional survey. YMSM reported on communication with mothers and fathers separately, data were analyzed separately for each parent, and YMSM were included in each analysis only if that respective parent knew they were gay or bisexual. The same factor structure of parent-adolescent communication about condoms was identified for data about mothers and fathers. Structural equation models were estimated. Facets of mother-adolescent communication were associated with attitudes about condoms, subjective norms for condom use, perceived behavioral control, intentions to use condoms, and indirectly, instances of condomless anal intercourse. Only quality of father communication was associated with norms and behavioral control. Parent-adolescent communication about condoms is associated with determinants of condom use behavior among YMSM, and mother communication exerted an indirect influence on HIV-related sexual risk behaviors. Interventions designed to enhance parentadolescent communication about condoms could prove efficacious in reducing HIV infections among YMSM

Systemic inflammatory response syndrome (SIRS) after extracorporeal membrane oxygenation (ECMO): Incidence, risks and survivals.

INTRODUCTION: Systemic inflammatory response syndrome (SIRS) is frequently observed after extracorporeal membrane oxygenation (ECMO) decannulation; however, these issues have not been investigated well in the past. METHODS: Retrospective chart review was performed to identify post-ECMO SIRS phenomenon, defined by exhibiting 2/3 of the following criteria: fever, leukocytosis, and escalation of vasopressors. The patients were divided into 2 groups: patients with documented infections (Group I) and patients with true SIRS (Group TS) without any evidence of infection. Survival and pre-, intra- and post-ECMO risk factors were analyzed. RESULTS: Among 62 ECMO survivors, 37 (60%) patients developed the post-ECMO SIRS phenomenon, including Group I (n = 22) and Group TS (n = 15). The 30-day survival rate of Group I and TS was 77% and 100%, respectively (p = 0.047), although risk factors were identical. CONCLUSIONS: SIRS phenomenon after ECMO decannulation commonly occurs. Differentiating between the similar clinical presentations of SIRS and infection is important and will impact clinical outcomes

Emittance growth in linear induction accelerators

The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT Axis-II LIA we measure an emittance higher than predicted by theoretical simulations, and even though this axis produces sub-millimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell (PIC) codes, although most of these are discounted based on beam measurements. The most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.Comment: 20th Int. Conf. on High-Power Particle Beams, Washington, DC, May, 201