The magnetic field and the temperature dependence of both guest and host fluorescence in pentacene-doped tetracene single crystals is studied. From a n analysis of the experimental results i t is concluded that pentacene enters substitutionally into the host lattice sites and that thermally activatedheterofission is site-dependent with activation energies =z (0.13 & 0.01) eV and 5 0.06 eV.From a kinetic fit t o the temperature dependence of the green and red fluorescence, a thermally activated host singlet exciton diffusion coefficient of = 2 x loe2 cm2/s is inferred; its activation energy is estimated to be (0.018 f 0.001) eV. The heterofission rate of Y (4.7 f 0.5) x 1O-IO cm3 s-1 is determined and location of the pentacene triplet level is found to be at (0.86 rf 0.03) eV.Es wird die Abhangigkeit sowohl der Gast-als auch der Wirts-Fluoreszenz in pentazendotierten Tetrazeneinkristallen vom Magnetfeld und yon der Temperatur untersucht. Aus einer Analyse der experimentellen Ergebnisse wird geschlossen, daB Pentazenzentren substitutionell auf Wirtsgitterplatze eingebaut werden und daO die thermisch aktivierte Heterospaltung gitterplatzabhan-

Objective Directly observed therapy is recommended worldwide for monitoring tuberculosis (TB) treatment; yet transportation and personnel requirements limit its use. We evaluated the feasibility and acceptability of “Video DOT” (VDOT), which allowed patients to record and transmit medication ingestion videos that were watched remotely by healthcare providers to document adherence. Methods We conducted a single-arm trial among TB patients in San Diego, CA (n=43) and Tijuana, B.C., Mexico (n=9) to represent high- and low-resources settings. Pre/post treatment interviews assessed participant characteristics and experiences. Adherence was defined as the proportion of observed doses to expected doses. Results Mean age was 34 years (range: 18–86), 54% were male, and 77% were non-Caucasian. Mean duration of VDOT use was 5.5 months (range: 1–11). Adherence was similar in San Diego (93%) and Tijuana (96%). Compared to time on in-person DOT, 92% preferred VDOT; 81% thought VDOT was more confidential; 89% never/rarely had problems recording videos; and 100% would recommend VDOT to others. Overall, 7 (13%) participants were returned to in-person DOT and 6 (12%) separate participants had their phone lost, broken or stolen. Conclusions VDOT was feasible and acceptable with high adherence in high- and low-resource settings. Efficacy and cost-effectiveness studies are needed.

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IntroductionMen who have sex with men (MSM) in developing countries such as Mexico have received relatively little research attention. In Tijuana, Mexico, a border city experiencing a dynamic HIV epidemic, data on MSM are over a decade old. Our aims were to estimate the prevalence and examine correlates of HIV infection among MSM in this city.MethodsWe conducted a cross-sectional study of 191 MSM recruited through respondent-driven sampling (RDS) in 2012. Biological males over the age of 18 who resided in Tijuana and reported sex with a male in the past year were included. Participants underwent interviewer-administered surveys and rapid tests for HIV and syphilis with confirmation.ResultsA total of 33 MSM tested positive for HIV, yielding an RDS-adjusted estimated 20% prevalence. Of those who tested positive, 89% were previously unaware of their HIV status. An estimated 36% (95% CI: 26.4–46.5) had been tested for HIV in the past year, and 30% (95% CI: 19.0–40.0) were estimated to have ever used methamphetamine. Independent correlates of being infected with HIV were methamphetamine use (odds ratio [OR]=2.24, p=0.045, 95% CI: 1.02, 4.92) and active syphilis infection (OR=4.33, p=0.01, 95% CI: 1.42, 13.19).ConclusionsOur data indicate that MSM are a key sub-population in Tijuana at higher risk for HIV. Tijuana would also appear to have the highest proportion among upper-middle-income countries of HIV-positive MSM who are unknowingly infected. More HIV prevention research on MSM is urgently needed in Tijuana.