关键词： People who inject drugs (PWID)   Russia   HIV and HCV epidemics   Drug generations   Drug epidemics   New psychoactive substances (NPS)  

摘要： Russia has an estimated 1.3-1.8 million people who inject drugs (PWID). In recent years concomitant decline of opioid use and rise of new psychoactive substances (NPS) use was observed. We conducted secondary analysis of survey data collected in 2019-2021 by a harm reduction organization in Saint-Petersburg, Russia (n = 978). Older PWID group (30+) was significantly more likely to use opioids (87.5% vs. 32.4%) than young PWID;young PWID used NPS four times more frequently than older ones (79.9% vs. 21.5%). The odds ratio of being an exclusive stimulant user but not an opioid user among younger cohorts is more than forty-five times higher than among older cohorts all else being equal (AOR = 47.38;95% CI 21.90-102.53;p < 0.001). The younger respondents were more than four times less likely to be HIV-positive than older participants (8.4% vs. 36.7%) and more than three times less likely to be HCV-positive (23.5% vs. 80.6%). Young PWID were significantly more prone to risk behaviors (syringes sharing in past month;having overdose in the last 12 months;and inconsistent condom use during past 3 months) than older PWID, which renders them vulnerable to rapid HIV and HCV transmission both by parenteral and sexual routes. It is possible that currently we are observing two epidemics- an "old" opioid epidemic among older generations of PWID and a new synthetic cathinones epidemic among younger generations of PWID. New forms of harm reduction tailored to the needs of NPS users along with expansion of existing harm reduction programs for opioid users are urgently needed.

关键词： Optical lattices  

摘要： Landau-Zener-Stückelberg-Majorana (LZSM) interference has significant application value in quantum state manipulation, extending quantum state lifetime, and suppressing decoherence. Optical lattice clock, with a long coherence time, increases the likelihood of experimentally observing time-domain LZSM interference. Although time-dominant Landau-Zener (LZ) Rabi oscillations have already been observed in optical lattice clock, the time-dominant LZSM interference sidebands in optical lattice clock remain unexplored. This study is based on an 87Sr optical lattice clock. By periodically modulating the frequency of the 698-nm clock laser and optimizing the parameters of the optical clock system, LZ transitions are achieved under the fast-passage limit (FPL). During the clock detection, two acoustic optical modulators (AOMs) are employed: AOM1 that compensates for the frequency drift of the clock laser and operates continuously throughout the experiment, and AOM2 that performs traditional clock transition detection and generates a cosine modulation signal by using an external trigger from the RF signal generator in Burst mode. Ultimately, the periodically modulated 698-nm clock laser with a frequency of (Figure Presented) is used to probe atoms, and the Hamiltonian is (Figure Presented). As the modulated laser interacts with the atoms, the interference phenomenon is exhibited in the time domain;adjusting the clock laser detuning allows for probing the time-domain LZSM interference sideband spectra at different detection times. The results show that the time-domain LZSM interference sideband consists of multiple sidebands. Specifically, ±kth order sidebands can be observed at δ/ωs = k, where k is an integer, representing constructive interference. Additionally, due to the different LZ Rabi oscillation periods for each sideband, the excitation fractions of different sidebands are also different, resulting in different excitation fractions for sidebands at the same clock dete