Evolution of the Illegal Substances Market and Substance Users' Social Situation and Health during the COVID-19 Pandemic.

The outbreak of the COVID-19 pandemic and the measures taken for tackling it had the potential to lead to deep modifications in the supply of illegal drugs and to impact substance users' health and social situation. To investigate this, we used mixed methods, i.e., quantitative data collected with a brief questionnaire from substance users receiving opioid agonist treatment in a treatment centre in Switzerland (N = 49), and qualitative data obtained using semi-structured phone interviews among a sub-group of participants (N = 17). We repeated data collection twice over four weeks to investigate trends over time (N = 51 and 14 at wave 2). Findings consistently showed the limited impact of the COVID-19 outbreak on the illegal substance market. Over the two waves, the supply, price and purity of three main illegal substances did not significantly vary. Substance use was estimated as usual by most, trending toward a decrease. The impact of the pandemic on participants' social situation and health was appraised as low to medium. Nevertheless, a minority of participants reported higher impact and multivariate analyses showed a more important impact for those who were female, younger, and not using multiple substances. This process was implemented quickly and provided an understanding of the short-term impact of the pandemic on drug markets and users

Charge disproportionation in YNiO3_{3} : ESR and susceptibility study

We present a study of the magnetic properties of YNiO$_{3}$ in the paramagnetic range, above and below the metal-insulator (MI) transition. The dc susceptibility, $\chi_{dc}$ (measured up to 1000 K) is a decreasing function of T for $T >$150 K (the N\'{e}el temperature) and we observe two different Curie-Weiss regimes corresponding to the metallic and insulator phases. In the metallic phase, this behaviour seems to be associated with the small ionic radius of Y% $^{3+}$. The value of the Curie constant for T$<$ T$_{MI}$ allows us to discard the possibility of Ni$^{3+}$ localization. An electron spin resonance (ESR) spectrum is visible in the insulator phase and only a fraction of the Ni ions contributes to this resonance. We explain the ESR and $\chi _{dc}$ behaviour for T $<$ T$_{MI}$ in terms of charge disproportionation of the type 2Ni$$ Ni$^{2+}$+Ni$^{4+},$ that is compatible with the previously observed structural transition across T$_{MI}$.Comment: 10 pages, 4 figures, submitted to Phys. Rev.