Redistribution of the Rydberg State Population Induced by Continuous-Spectrum Radiation

We consider the redistribution of the Rydberg state population resulting from multistep cascade transitions induced by radiation with a continuous spectrum. The population distribution is analyzed within the space of quantum numbers n and l. The dynamics of the system are studied using both the numerical solution of kinetic equations and the diffusion approximation based on the Fokker–Planck equation. The main path of the redistribution process is determined.

Risk heterogeneity in compartmental HIV transmission models of ART as prevention in Sub-Saharan Africa: A scoping review

ObjectiveTransmission models provide complementary evidence to clinical trials about the potential population-level incidence reduction attributable to ART (ART prevention impact). Different modelling assumptions about risk heterogeneity may influence projected ART prevention impacts. We sought to review representations of risk heterogeneity in compartmental HIV transmission models applied to project ART prevention impacts in Sub-Saharan Africa.DesignScoping review to identify common modelling assumptions and applications.MethodsWe systematically reviewed studies published before January 2020 that used non-linear compartmental models of sexual HIV transmission to simulate ART prevention impacts in Sub-Saharan Africa. We summarized data on model structure/assumptions (factors) related to risk and intervention heterogeneity, and explored crude associations of ART prevention impact with modelled factors.ResultsOf 1384 search hits, 94 studies were included, which primarily modelled medium/high prevalence epidemics in East/Southern Africa. 64 studies considered sexual activity stratification and 39 modelled at least one key population. 21 studies modelled faster/slower ART cascade transitions (HIV diagnosis, ART initiation, or cessation) by risk group, including 8 with faster and 4 with slower cascade transitions among key populations versus the wider population. Models without activity stratification predicted the largest ART prevention impacts, followed by models with key populations that had faster cascade transitions versus the wider population.ConclusionsAmong compartmental transmission models applied to project ART prevention impacts, representations of risk heterogeneity and projected impacts varied considerably, where models with less heterogeneity tended to predict larger impacts. The potential influence of modelling assumptions about risk and intervention heterogeneity should be further explored.

Диффузионная динамика ридберговских состояний в поле излучения с непрерывным спектром

Redistribution of population and ionization of atomic Rydberg states due to multistep cascade transitions between states under the influence of radiation with continuous spectrum is considered. Consideration is carried up both by simulation of kinetic equations for state populations and with the use of a diffusion approximation based on the Fokker-Planck equation. On the example of sodium atom under the influence of radiation with rectangular spectrum a good agreement between the diffusion approximation and the kinetic equation simulation is shown. In the frame of the diffusion approximation some estimations are derived for the state populations, ionization rates and minimal spectral density of radiation necessary for significant ionization.