This study examined contextual influences on the relationship between peer norms for condom use and risky sexual behavior among African-American men who have sex with men. Analyses assessed the moderating effects of socio-demographic, socio-contextual, and health-related variables. One thousand forty African-American men, who have sex with men, ages 17 to 25 years, were surveyed as part of the Community Intervention Trial for Youth (CITY) from 1999 to 2002 in Atlanta, Georgia. Findings supported the hypothesis that participants who engaged in unprotected insertive anal intercourse, socio-contextual variables moderated the relationship between peer norms and risky sexual behavior. Findings also supported the hypothesis that participants who engaged in unprotected receptive anal intercourse, both socio-demographic variables and a health variable moderated the relationship between peer norms and risky sexual behavior. Findings have implications for intervention, policy, and research, including a need for interventions that recognize the contexts of influence that shape African-American MSM sexual behavior and that support norms for consistent condom use in both steady and casual sexual relationships.

Men who have sex with men (MSM) are disproportionately affected by HIV infection and account for more than half of all new HIV infections diagnosed in the U. S. The purpose of this study was to explore factors that influence sexual behavior among sexually active HIV positive MSM using constructs from the health belief model (HBM). A cross-sectional, correlational study was conducted with a non-randomized sample of 216 HIV positive MSM. Participants were predominantly Black/African American (85.6%). The mean age of the sample was 43.02 years (SD = 9.74) and ages ranged from 19 to 66. More than 90% reported a high school educational level or greater; and nearly half (47.2%) had been diagnosed with HIV for more than 10 years. The overall model predicted that participants who had perceived less severity of living with HIV and who had a positive attitude toward condom use were more likely to practice safer sex, accounting for 24% of the variance in sexual behavior (p < .001). When controlling for demographic characteristics (age, number of years diagnosed as HIV positive, number of recent sexual partners, and current antiretroviral medication use), the overall model accounted for 41% of the variance (p < .001). Participants who had a fewer number of recent sex partners and who had a positive attitude toward condom use were more likely to practice safer sex. Additionally, those who practiced safer sex (n = 58, 27%) reported significantly higher levels of perceived severity of living with HIV (p = .037), perceived benefits of safe sex (p = .018), perceived barriers to safe sex (p < .001), and self-efficacy for negotiating safe sex (p = .013) compared to those who did not practice safer sex (n = 157, 73%). Results from the study indicated there was a high prevalence of unsafe sexual practices among the participants. These findings support the need for additional research to explore factors that influence sexual behavior among HIV positive MSM with an emphasis on testing interventions that support safe sex practices.

The purpose of this study is to explore how different discourses about risk linked to HIV prevention is likely to affect the decisions on the distribution of state funding for preventive activities aimed at 'men who have sex with men' (MSM). This by making qualitative interviews with principals that have an impact on this decision. Using a discourse analytic approach, based on both theoretical and methodological foundations, I investigate the discursive constructions of risk of HIV linked to certain groups and behaviors. MSM is found in the material placed into two different formations of groups, on one hand by the behavior on the other hand on the basis of identity. The identity position is organized discursively from a “victim” position while MSM provides an "operator" position. MSM is thus incompatible with the victim's position needed to be taken into account in the allocation of HIV prevention funds. On this basis I argue that the impact of heteronormativity, combined with an unwillingness to stigmatize, threatens to make HIV prevention ineffective when it is distributed on a different premise than epidemiological trends.

Magnetische Formgedächtnsilegierungen haben die besondere Fähigkeit, sich im äußeren Magnetfeld zu verformen. Dies geschieht aufgrund von Zwillingsgrenzenbewegung in der martensitischen Tieftemperaturphase. Da der Effekt bislang an Einkristallen untersucht wurde, ist es das Ziel dieser Arbeit, den Effekt an polykristallinen Proben nachzuweisen. Dafür wurden Proben nach dem Prinzip der gerichteten Erstarrung präpariert. Deren Kristallstruktur wurde durch geeignete Zusammensetzung und Wärmebehandlung einphasig eingestellt. Mechanisches Training und weitere Wärmebehandlungen ermöglichten schließlich die Demonstration der magnetischen Dehnung von ca. 1 % an polykristallinen Proben. Durch zusätzliche Einkopplung akustischer Wellen konnte die Dehnung auf 2,2 % gesteigert werden.

Objective: The rectal mucosa is highly susceptible to HIV infection. Mucosal fluid contains soluble immune proteins that influence HIV infection, and previous studies have shown unique mucosal protein expression in HIV-exposed seronegative (HESN) populations, which may contribute to reduced HIV susceptibility. However, the key correlates of susceptibility at the rectal mucosa have not been well defined, which is a critical knowledge gap for our understanding of HIV pathogenesis. Methods: Rectal lavage from low risk men was screened for HIV-neutralizing activity in a TZM-bl reporter cell line against an R5-tropic HIV virus. Label-free tandem mass spectrometry was used to characterize soluble proteins within rectal lavage samples from a low-risk cohort of men (n=15), and HESN men who have sex with men (MSM; n=25). Protein expression between populations was compared using adjusted t tests (p<0.05), and was interpreted using hierarchical clustering and DAVID biofunctional analysis. Protein expression was further analyzed using survey data on sexual behaviours. Proteins associated with the HESN population were screened for antiviral activity in TZM-bl and PBMC culture against an R5- and X4-tropic virus. Major Results: Rectal mucosal fluid was able to inhibit HIV infection in vitro by 40% (p<0.05). Mass spectrometry identified 30/341 (9%) proteins deferentially expressed (DE) in HESN MSM. DE proteins held functions in immunity (p=6.68x10-6, p=0.001) and epithelial barrier development (p=1.81x10-4; p=0.01); notably, specific antiproteases were elevated in HESN secretions, two of which were screened for antiviral activity. Serpin B4 (+2.52 L2FD; p=1.09x10-5), showed significant inhibition of HIV in TZM-bl (45% BaL, 34% IIIB; p<0.05) and PBMC culture (37% BaL, 49% IIIB; p<0.05); cystatin A (+1.52 L2FD; p=1.40x10-3) showed no inhibitory effects. Serpin B4 expression was not associated with frequency of oral intercourse (p=0.32), partner viral load (r=0.16; p=0.29) or presence of HIV neutralizing IgA in secretions (p=0.52). Conclusions: This thesis reports the use of proteomics to understand HIV-susceptibility at the rectal mucosa, and identified serpin B4 as a novel antiviral immune correlate in a population of HESN MSM. These results may help guide future studies of prevention technologies, such as microbicides or vaccines, which would ultimately help limit the spread of HIV. / February 2016

Visible-blind and solar-blind ultraviolet photodetectors based on GaN/AlGaN were designed, fabricated, and characterized for commercial and military applications. High performance back-illuminated solar-blind MSM achieved external quantum efficiency of ~48%. The dark current of 40x40μm MSM was less than the instrument measurement limitation of 20fA for a bias <100V. No photoconductive gain was observed. With an n-type doped high-Al ratio "window" Al₀.₆Ga₀.₄N layer, back-illuminated solar-blind p-i-n photodiode achieved a quantum efficiency of ~55% at zero-bias. Absorption edge study of both MSM and p-i-n photodetectors, based on device spectral responses, resulted in a performance comparison of MSMs and p-i-ns, as the solar-blind photodetection requires a sharp solar-blind rejection. Photoconductive detectors and avalanche photodetectors, with the internal gain advantage, have been discussed as well. A 30μm diameter GaN avalanche photodiode achieved a gain >23, with a dark current less than 100pA. The breakdown showed a positive temperature coefficient of 0.03 V/K that is characteristic of avalanche breakdown. SiC APDs, as candidates for visible-blind applications, have been designed, fabricated and characterized. An avalanche gain higher than 10⁵, with a dark current less than 1nA, showed the potential of SiC APD replacing PMTs for high sensitivity visible-blind UV detection. A silicon-based optical receiver has been presented in the Appendix. With the photodiode internal avalanche gain ~4, a sensitivity ~-6.9dBm at 10Gbps has been achieved. / text

Epidemiologic evidence shows that the incidence of HIV among men who have sex with men (MSM) is on the rise. high-risk sexual behaviors are the primary mode of transmission and are responsible for increased rates of infection. a growing body of evidence suggests that endorsement of normative beliefs and values regarding manhood and masculinity, or masculinity ideology, may help to explain certain high-risk sexual behaviors. this study investigated the associations between a measure of masculinity ideology and sexual risk taking among a sample of MSM. in addition, indirect pathways in which masculinity ideology may lead to sexual risk taking were explored, including the use of the internet to meet sex partners and the use of drugs during sexual encounters. a cross-sectional, web-based survey was used to collect data from participants recruited via the internet (n=907) Correlation and multiple regression analysis supported the hypotheses that masculinity ideology was positively associated with the number of sexual partners and frequency of unprotected anal intercourse in the previous six months. Higher endorsement of masculinity ideology was also positively associated with greater intentions for unprotected anal sex. This study adds to the growing body of literature on the subject of gender ideologies and sexual behavior and offers additional avenues for public health research.

The current study examined the capacity of the Theory of Planned Behaviour (TPB) and the Prototype/Willingness model (P/W model) to predict intention to have unsafe sex with new and regular partners as well as frequency of unsafe sex in a sample of men who have sex with men (MSM) sample. The study also examined aspects of the sexual situation immediately prior to or during unsafe sexual intercourse (such as substance use, venue and emotional state) to determine whether there were any significant correlations and group differences. One hundred and fifty-eight male participants between the ages of 18-26 who have had sex with another male in the last nine months completed an online survey of sexual habits, TPB and P/W model variables. With the exception of prototypes, the results showed significant group difference in terms of TPB and P/W model variables between risk groups. Furthermore, there was no significant difference between models in predictive capacity in terms of either intention or frequency of unsafe sex. The results of the study suggested participants were generally only having unsafe sex with regular partners, that in older samples it may be more parsimonious to use the TPB than P/W model and that it is important to measure TPB variables in terms of both new and regular partners for increased accuracy and greater applicability in terms of HIV/STI interventions.

This study examined contextual influences on the relationship between peer norms for condom use and risky sexual behavior among African-American men who have sex with men. Analyses assessed the moderating effects of socio-demographic, socio-contextual, and health-related variables. One thousand forty African-American men, who have sex with men, ages 17 to 25 years, were surveyed as part of the Community Intervention Trial for Youth (CITY) from 1999 to 2002 in Atlanta, Georgia. Findings supported the hypothesis that participants who engaged in unprotected insertive anal intercourse, socio-contextual variables moderated the relationship between peer norms and risky sexual behavior. Findings also supported the hypothesis that participants who engaged in unprotected receptive anal intercourse, both socio-demographic variables and a health variable moderated the relationship between peer norms and risky sexual behavior. Findings have implications for intervention, policy, and research, including a need for interventions that recognize the contexts of influence that shape African-American MSM sexual behavior and that support norms for consistent condom use in both steady and casual sexual relationships.

The most promising technology for radiography is active matrix flat panel imaging systems (AMFPI). However, AMFPI systems are relatively expensive in comparison with conventional computed radiography (CR) systems. Therefore for general radiography applications low cost systems are needed, especially in hospitals and healthcare systems of the developing countries. The focus of this research is the fabrication and characterization of a low cost amorphous silicon metal-semiconductor-metal photodetector as a photosensitive element in a AMFPI systems. Metal-Semiconductor-Metal photodetectors (MSM-PD) are attractive as sensors due to their ease of fabrication and compatibility with thin film transistor fabrication process primarily because there is no p+ doped layer in comparison with conventional p-i-n photodiodes. We have reported low dark current lateral a-Si MSM-PD (lower than 20pA/mm2 ) with responsivity of 280mA/W and EQE of 65 percent to green light ( l = 525nm). These improvement are achieved by introduction of a PI blocking layer and operating the device at high electric field (15 V/µm). This new structure eliminates the need of p+ and n+ layers which makes this structure fully compatible with the a-Si:H TFT fabrication process and consequently a low cost flat panel imager. Further, in this study we have investigated the effect of the spacing and width of the comb structure in the proposed lateral a-Si MSM-PD to determine the best configuration. Moreover, a-Si MSM-PD with PI blocking layer shows a linear behaviour to the photon flux in the wide range of 200nW/cm2 - 300µW/cm2 intensity of the incoming light. In comparison to vertical p-i-n structures, the reported MSM lateral device shows gains in terms of dynamic range, ease of fabrication (no p+ layer) without any deterioration in EQE and responsivity. This results are promising and encourage the development of a-Si lateral MSM-PD for indirect conversion large area medical imaging applications and especially low cost flat.