Socio-ecologic Correlates of HIV/AIDS-Related Sexual Risk Behavior of African American Emerging Adults.

There is growing evidence showing that patterns of individual sexual risk behaviors are insufficient in explaining the disproportionate HIV/AIDS burden borne by African Americans. Instead, dynamic features of social, economic, political, and geographic contexts play a more determining role. However, not enough studies have examined the impact of multi-level factors including neighborhood-level influences on HIV/AIDS sexual risk among African American emerging adults using a socio-ecologic perspective. Anchored on the socio-ecologic framework, this study examines the collective role of relevant socio-ecologic determinants of sexual risk-taking among African American emerging adults. Results from both bivariate and multivariate analyses revealed that individual and neighborhood-level variables were significantly associated with sexual risk in our study population partially confirming the hypothesis of the study. Male gender, educational attainment, and neighborhood social disorder were the strongest predictors of sexual risk. Our findings contribute to the vast literature on sexual risk behavior patterns of young adults, and increasing evidence demonstrating the role of contextual factors as stronger predictors of sexual risk and HIV infection among at-risk youth. Our findings, however, underscore the need for further research on the pathways of HIV socio-behavioral vulnerability in this demographic group.

Laser power density dependent energy transfer between Tm3+ and Tb3+: tunable upconversion emissions in NaYF4:Tm3+,Tb3+,Yb3+ microcrystals.

Energy transfer between Tm3+ and Tb3+ dependent on the power density of pump laser was investigated in NaYF4: Tb3+,Tm3+,Yb3+ microcrystals. Under the excitation of a 976-nm near-infrared laser at various power densities, Tb3+-Tm3+-Yb3+ doped samples exhibited intense visible emissions with tunable color between green and blue. The ratio of blue and green emission were determined by energy transfer between Tm3+ and Tb3+. When the power density of pump laser was low, the energy transfer process from Tm3+ (3F4) to Tb3+ (7F0) occurred efficiently. Upconversion processes in Tm3+ were inhibited, only visible emissions from Tb3+ with green color were observed. When the power density increased, energy transfer from the 3F4 (Tm3+) to 7F0 level (Tb3+) was restrained and population on high energy levels of Tm3+ was increased. Contribution of upconversion emissions from Tm3+ gradually became dominant. The emission color was tuned from green to blue with increasing the power density. Energy transfer processes between low-lying levels of activators, such as Tm3+ will greatly reduce the population on certain levels for further high-order upconversion processes. The Tb3+-Tm3+-Yb3+ doped phosphors are promising materials for detecting the condition of power density of the invisible near-infrared laser.

Sexual Behavior Patterns of Black Young Adults in Georgia: Results from a Latent Class Analysis.

The state of Georgia ranks first in the rate of new diagnosis of HIV/AIDS, yet studies focused on understanding the drivers of this epidemic in the most at-risk groups outside the Atlanta Metropolitan Statistical Area (MSA) remain sparse. Among the many consequences of this is the inability to effectively design tailored intervention programs that appropriately address the reduction of HIV/AIDS and other STDS in the state. Reducing disparities in HIV/AIDS remains an important goal in the National HIV/AIDS Strategy. Given the disproportionate burden of the HIV/AIDS epidemic among Blacks in the state of Georgia, there is a significant need to focus research attention on the sexual behavior of young people that predisposes them to increased risk of HIV/AIDS infection. The current study used latent class analysis (LCA) to examine the sexual behavior patterns of Black young adults living in Georgia. LCA results revealed a two-class fit with distinct sexual behavior patterns. Gender and educational attainment emerged as significant predictors of class membership. Our findings contribute to the vast literature showing that sexual behavior patterns of Black young adults are not homogenous, and underscore the significance of socio-demographic and contextual factors in shaping sexual risk behavior.