A novel experimental approach to search for double electron capture (EC/EC) is discussed in this article. R&D for a new generation EC/EC spectrometer based on silicon pixel detectors (SPDs) has been ...conducted since 2009 for an upgrade of the TGV experiment. SPDs built on Timepix technology with a spectroscopic readout from each individual pixel are an effective tool to detect the 2 upsilon EC/EC signature of the two low energy X-rays hitting two separate pixels. The ability of SPDs to indentify alpha / beta / gamma particles and localize them precisely leads to effective background discrimination and thus considerable improvement of the signal-to-background ratio (S/B). A multi-SPD system, called a Silicon Pixel Telescope (SPT), is planned based on the experimental approach of the TGV calorimeter which measures thin foils of enriched EC/EC-isotope sandwiched between HPGe detectors working in coincidence mode. The sources of SPD internal background have been identified by measuring SPD radiopurity with a low-background HPGe detector as well as by long-term SPD background runs in the Modane underground laboratory (LSM, France), and results of these studies are presented.
Excitation of surface waves by a relativistic electron beam propagating over a conducting cylindrical medium (metal or highly ionized plasma) is investigated theoretically. Dispersion relations ...describing the linear interaction of surface electromagnetic waves with a monoenergetic electron beam are derived, and the growth rates and spatial amplification factors of excited waves are determined. Condition for the nonlinear trapping of the beam electrons by a surface wave is used to determine the maximum amplitude of the excited wave and the optimal radiator length. The electric field of a surface wave excited by an electron beam is estimated for a particular case.
This paper presents an analysis on the possibilities of controlling the radiation pattern of Yagi-type multielement plasma vibrator antennas. The plasma vibrator antenna in its operating band is ...shown as a narrow-band filter. In a multielement linear plasma vibrator antenna, turning off a passive plasma vibrator makes it possible to control the beam width electronically.
Investigations of the magnetic field influence on energy (power) released in discharge, the electronic temperature, particle concentration, and the radiation of plasma of the channel-arc stages has a ...practical focus. It was found that the magnetic field leads to an increase in current density, conductivity, and specific energy input and a decrease in the formation times of all stages of discharge development, transverse integral radiation, and channel expansion rate, and shifts in the maximum spectral density of radiation in the ultraviolet region with simultaneous generation of new spectral lines. The magnetic field decreases the rate of spark channel expansion and the loss of transverse radiation and increases the specific power, conductivity and temperature of the plasma at channel-arc stages, creating conditions for obtaining a hot plasma.
A new experiment devoted to searches for double electron capture in Cd-106 decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The limit ...T (1/2)(2 nu EC/EC) > 2.0x10(20) yr at a 90%confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope Cd-106 to 99.57%. The limits T (1/2)(KL, 2741 keV) > 0.9 x 10(20) yr and T (1/2)(KK, 2718 keV) a parts per thousand << 1.4 x 10(20) yr at a 90% C.L. on the neutrinoless decay of Cd-106 were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope Cd-106.
This paper aims to analyze the mechanism of power absorption and to reveal, both experimentally and numerically, the basic factors determining the ability of plasma to absorb RF power. This is done ...by determining the plasma equivalent resistance value under different conditions in a low-pressure RF inductive discharge such as different antenna shape, working gas pressure, electron density, operating frequency and geometrical dimensions of the plasma source. Experimental and numerical results show that the plasma equivalent resistance changes non-monotonously with an increase in electron density, increases with an increase in neutral gas pressure, and that the maximum plasma equivalent resistance shifts toward higher electron densities when the operating frequency is increased.
A new experiment devoted to searches for double electron capture in sup.106Cd decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The ...limit T.sub.1/2 (2υEC/EC) > 2.0 x 10.sup.20 yr at a 90% confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope sup.106Cd to 99.57%. The limits T.sub.1/2(KL 2741 keV) > 0.9 x 10.sup.20 yr and T.sub.1/2(KK 2718 keV) >> 1.4 x 10.sup.20yr at a 90% C.L. on the neutrinoless decay of sup.106Cd were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope sup.106Cd. DOI: 10.1134/S1063778815060058
Objectives
Pre‐exposure prophylaxis (PrEP) for HIV infection is an important intervention for control of the HIV epidemic. The incidence of HIV infection is increasing in the countries of Central and ...Eastern Europe (CEE). Therefore, we investigated the change in PrEP use in CEE over time.
Methods
The Euroguidelines in Central and Eastern Europe (ECEE) Network Group was initiated in February 2016 to compare standards of care for HIV and viral hepatitis infections in CEE. Data on access to PrEP were collected from 23 countries through online surveys in May–June 2017 (76 respondents) and in November 2018–May 2019 (28 respondents).
Results
About 34.2% of respondents stated that tenofovir/emtricitabine (TDF/FTC) was licensed for use in their country in 2017, and 66.7% that it was licensed for use in 2018 (P = 0.02). PrEP was recommended in national guidelines in 39.5% of responses in 2017 and 40.7% in 2018 (P = 0.378). About 70.7% of respondents were aware of “informal” PrEP use in 2017, while 66.6% were aware of this in 2018 (P = 0.698). In 2018, there were 53 centres offering PreP (the highest numbers in Poland and Romania), whereas six countries had no centres offering PreP. The estimated number of HIV‐negative people on PreP in the region was 4500 in 2018. Generic TDF/FTC costs (in Euros) ranged from €10 (Romania) to €256.92 (Slovakia), while brand TDF/FTC costs ranged from €60 (Albania) to €853 (Finland).
Conclusions
Although the process of licensing TDF/FTC use for PrEP has improved, this is not yet reflected in the guidelines, nor has there been a reduction in the “informal” use of PrEP. PrEP remains a rarely used preventive method in CEE countries.
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