Effect of exchange electron-electron interaction on conductivity of InGaAs single and double quantum wells in ballistic regime

We report an experimental study of quantum conductivity corrections for two-dimensional electron gas in a GaAs/InGaAs/GaAs single and double quantum wells in a wide temperature range (1.8-100) K. We perform a comparison of our experimental data for the longitudinal conductivity at zero magnetic field to the theory of interaction-induced corrections to th transport coefficients. In the temperature range from 10 K up to (45-60) K, wich covers the ballistic interaction regimes for our samples, a rather good agreement between the theory and our experimental results has been found

Phenomenological features of mortality and morbidity dynamics in Tomsk versus heliogeophysical activity

The influence of heliogeophysical activity on the morbidity and mortality of the population in Tomsk is studied epidemiologically on the basis of regional data. The biological effectiveness of heliogeophysical factors selected on the basis of the Karhunen–Loeve method from epidemiological data on the morbidity and mortality in Tomsk in 1990–2008 is estimated. An analysis of the impact of variations in heliogeophysical activity on morbidity and mortality (according to the International Statistical Classification of Diseases and Related Health, ICD-10) showed the existence of common factors within different nosological classes that reliably correlate with the major components of variations in characteristic indices of heliogeophysical activity

Exploratory analysis of time from HIV diagnosis to ART start, factors and effect on survival: A longitudinal follow up study at seven teaching hospitals in Ethiopia

Background: the HIV care in Ethiopia has reached 79% coverage. The timeliness of the care provided at the different levels in the course of the disease starting from knowing HIV positive status to ART initiation is not well known. This study intends to explore the timing of the care seeking, the care provision and associated factors.Methods: This is a longitudinal follow-up study at seven university hospitals. Patients enrolled in HIV care from September 2005 to December 2013 and aged ≥14 years were studied. Different times in the cascade of HIV care were examined including the duration from date HIV diagnosed to enrollment in HIV care, duration from enrollment to eligibility for ART and time from eligibility to initiation of ART. Ordinal logistic regression was used to investigate their determinants while the effect of these periods on survival of patients was determined using cox-proportional hazards regression.Results: 4159 clients were studied. Time to enrollment after HIV test decreased from 39 days in 2005 to 1 day after 2008. It took longer if baseline CD4 was higher, and eligibility for ART was assessed late. Young adults, lower baseline CD4, HIV diagnosis<2008, late enrollment, and early eligibility assessment were associated with early ART initiation. Male gender, advanced disease stage and lower baseline CD4 were consistent risk factors for mortality.Conclusion and recommendation: Time to enrollment and duration of ART eligibility assessment as well as ART initiation time after eligibility is improving. Further study is required to identify why mortality is slightly increasing after 2010.Key words: HIV, HIV testing, enrollment, eligibility, antiretroviral therapy, mortality, Ethiopia

Temperature dependence of quantum lifetime in n-InGaAs/GaAs structures with strongly coupled double quantum wells

Longitudinal ρxx(B) and Hall ρxy(B) magnetoresistances are experimentally investigated as a function of in-plane and transverse magnetic fields in n-InGaAs/GaAs nanostructures with strongly-coupled double quantum wells in the temperature range T = 1.8-70 K and magnetic fields B = 0-9.0 T. Experimental data on the temperature dependence of quantum lifetime in diffusive (kBT/τtr ≪ 1) and ballistic (kBT/τtr ≫ 1) regimes are reported. It has been found that in the ballistic regime in the temperature range where kBT/EF < 0.1, the observed quadratic temperature dependence of quantum lifetime is determined by inelastic electron-electron scattering. However, the temperature dependence of quantum lifetime cannot be quantitatively described by the existing theories in the whole temperature range. © 2013 American Institute of Physics

Tunneling effects in tilted magnetic fields in n-InGaAs/GaAs structures with strongly coupled double quantum wells

The effects of tunneling between two parallel two-dimensional electron gases in n-InGaAs/GaAs nanostructures with strongly coupled double quantum wells with a change in the in-plane component of a tilted magnetic field (up to Bnorm of matrix = 9.0 T) in the temperature range T = 1.8-70.0 K are investigated. A nonmonotonic temperature dependence of the inverse quantum lifetime τq -(T) is obtained from analysis of the dependence of the longitudinal resistance on the parallel component of the tilted magnetic field at fixed temperatures, ρxx(Bnorm of matrix, T). The quadratic portion of this dependence is found to be due to the contribution of inelastic electron-electron scattering. The decrease in the inverse quantum lifetime τq -(T) at T &gt; 0.1T F cannot be described within known theories; it seems, it is not related to the processes of electron momentum relaxation. © 2013 Pleiades Publishing, Ltd

Magnitude of Antiretroviral Drug toxicity in adult HIV patients in Ethiopia: A cohort study at seven teaching hospitals

Background: The introduction of antiretroviral therapy (ART) has resulted in significant mortality reduction and improvement in the quality of life. However, this has come at a cost of increased drug toxicity. The objective of this study was to assess the patterns and predictors of ART toxicity in adult HIV patients in Ethiopia.Methods: This is a prospective cohort study conducted at seven teaching hospitals between September 2009 and December 2013 involving 3921 HIV patients on ART. Adverse drug reactions (ADR) due to ART were identified based on clinical assessment and/or laboratory parameters. Multivariable random effects Poisson regression analysis was used to identify factors independently associated with toxicity.Result: ADR due to ART drugs was reported in 867 (22.1 %) of the participants; 374 (9.5%) had severe forms. About 87% of reported toxicities were limited to three organ systems – the skin, nervous system and blood. The overall incidence of ADR was 9 per 100 person years. About a third of toxicities occurred during the first six months after ART initiation with the incidence rate of 22.4 per 100 person years. Concomitant anti-tuberculosis treatment was the strongest independent predictor of toxicity.Conclusion: ADR was found to be highly prevalent in HIV patients on ART at tertiary hospitals in Ethiopia. Most of these conditions occurred early after ART initiation and in those with concomitant anti-tuberculosis treatment. Thus, routine monitoring of patients on ART should be strengthened with particular emphasis in the first 6 months. Strategies should also be devised to replace older and more toxic agents with newer and safer drugs available.Key words: HIV, ART, adverse drug reaction, incidence rate, ACM, Ethiopi

Quasiclassical calculations of Landau level spectrum for 20.5-nm-wide H gTe quantum well: "extremum loop" model and effects of cubic symmetry

Quasiclassical calculations of the effective cyclotron mass and the spectrum of Landau levels have been carried out for carriers of the size-quantized H2 subband with a nonmonotonic dispersion law, which forms a valence band of 20.5-nm-wide HgTe quantum well with an inverted band structure. The model of the so-called "extremum loop", previously developed by Rashba and Sheka for semiconductors with a wurtzite lattice, has been used for calculations. The results obtained are compared both with the empirical picture and with quantum-mechanical calculations of the Landau level spectrum for the HgTe quantum well in the semimetallic phase. © 2021 Author(s).The research was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme “Electron” No. AAAA-A18-118020190098-5), supported in part by RFBR, Project No. 18-02-00172. We are grateful to Novik E. G. for the contribution to the band structure calculations of the real 20 nm HgTe quantum well