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Sexual discounting, which describes delay discounting of later protected sex vs. immediate unprotected sex (e.g., sex now without a condom vs. waiting an hour to have sex with a condom), is consistently linked to sexual risk behavior. Estimates suggest that over two-thirds of HIV transmissions occur between individuals in committed relationships, but current sexual discounting tasks examine sexual discounting only with hypothetical strangers, leaving a gap in our understanding of sexual discounting with committed sexual partners. We used the Sexual Discounting Task (SDT) to compare discounting rates between men who have sex with men (MSM; n = 99) and heterosexual men (n = 144) and tested a new SDT condition evaluating sexual discounting with main partners. MSM in committed relationships discounted protected sex with their main partner at higher rates than heterosexual men, and discounting rates correlated with self-report measures of condom use, impulsivity/sensation seeking, and substance use. These findings suggest that sexual discounting is a critical factor potentially related to increased HIV transmission between MSM in committed relationships and may be an important target for intervention and prevention.

The aim of this study was to evaluate adult patient doses in Russia in the context of patient protection. Effective doses from x-ray and nuclear medicine examinations were assessed using two approaches. The first was based on data collection performed by the authors in hospitals in St. Petersburg and other 17 Russian regions. The second approach was to assess mean doses through the collective dose estimated annually within the federal data bank ESKID. In 2015, 203 million examinations were conducted in Russia, i.e. 1.4 examinations per capita. The number of examinations has increased by 35% over the last 10 years. Patient doses from x-ray examinations are strongly dependent on the imaging modality. Mean dose increases by an order of magnitude with each x-ray modality from dental examinations (0.01-0.1 mSv) to radiography (0.1-1 mSv), fluoroscopy and CT (1-10 mSv) and to interventional examinations (more than 10 mSv). Mean doses for x-ray examinations are comparable with that of foreign countries. Scintigraphy examinations with 99m Tc are associated with mean doses of 1-5 mSv. Mean doses from PET/CT whole body examinations are 15-25 mSv with similar contributions from CT and radiopharmaceuticals. In nuclear medicine, patient doses are lower compared to other countries. According to ESKID data the collective dose from medical exposure in Russia has decreased from 140 000 man-Sv in 2000 to 77 000 man-Sv in 2015. Medical exposure contributes about 13% into a total collective dose. The maximum contribution was from CT examinations, i.e. 45% in 2015. A range of mean doses between different hospitals was up to two orders of magnitude for radiography and one order of magnitude for CT. In interventional studies, the scatter of individual doses was significant. Significant variations in doses between hospitals and some regions indicate the potential for optimization with the focus on interventional examinations, CT and nuclear medicine examinations combined with CT.