Pecularities of Hall effect in GaAs/{\delta}<Mn>/GaAs/In\timesGa1-\timesAs/GaAs (\times {\approx} 0.2) heterostructures with high Mn content

Transport properties of GaAs/{\delta}/GaAs/In\timesGa1-\timesAs/GaAs structures containing InxGa1-xAs (\times {\approx} 0.2) quantum well (QW) and Mn delta layer (DL) with relatively high, about one Mn monolayer (ML) content, are studied. In these structures DL is separated from QW by GaAs spacer with the thickness ds = 2-5 nm. All structures possess a dielectric character of conductivity and demonstrate a maximum in the resistance temperature dependence Rxx(T) at the temperature {\approx} 46K which is usually associated with the Curie temperature Tc of ferromagnetic (FM) transition in DL. However, it is found that the Hall effect concentration of holes pH in QW does not decrease below TC as one ordinary expects in similar systems. On the contrary, the dependence pH(T) experiences a minimum at T = 80-100 K depending on the spacer thickness, then increases at low temperatures more strongly than ds is smaller and reaches a giant value pH = (1-2)\cdot10^13 cm^(-2). Obtained results are interpreted in the terms of magnetic proximity effect of DL on QW, leading to induce spin polarization of the holes in QW. Strong structural and magnetic disorder in DL and QW, leading to the phase segregation in them is taken into consideration. The high pH value is explained as a result of compensation of the positive sign normal Hall effect component by the negative sign anomalous Hall effect component.Comment: 19 pages, 6 figure

Заседание рабочей группы ENFSI по судебно- баллистической экспертизе (Эспоо, Финляндия)

The paper reports on the outcomes of the 24th Annual Meeting of the Firearms/GSR Expert Working Group of the European Network of Forensic Science Institutes (ENFSI) that was held in October 2017 in Finland.Представлены итоги 24-й ежегодной встречи рабочей группы Европейской сети судебно-экспертных учреждений (ENFSI) по судебно-баллистической экспертизе, прошедшей в октябре 2017 года в Финлянди

Review of scientific topics for Millimetron space observatory

This paper describes outstanding issues in astrophysics and cosmology that can be solved by astronomical observations in a broad spectral range from far infrared to millimeter wavelengths. The discussed problems related to the formation of stars and planets, galaxies and the interstellar medium, studies of black holes and the development of the cosmological model can be addressed by the planned space observatory Millimetron (the "Spectr-M" project) equipped with a cooled 10-m mirror. Millimetron can operate both as a single-dish telescope and as a part of a space-ground interferometer with very long baseline.Comment: The translation of the original article in Physics Uspekhi http://ufn.ru/ru/articles/2014/12/c

Multi-Frequency Synthesis of VLBI Images Using a Generalized Maximum Entropy Method

A new multi-frequency synthesis algorithm for reconstructing images from multi-frequency VLBI data is proposed. The algorithm is based on a generalized maximum-entropy method, and makes it possible to derive an effective spectral correction for images over a broad frequency bandwidth, while simultaneously reconstructing the spectral-index distribution over the source. The results of numerical simulations demonstrating the capabilities of the algorithm are presented.Comment: 17 pages, 8 figure

Разъяснение некоторых положений методики установления принадлежности объекта к огнестрельному оружию

The paper clarifies some of the provisions of the «Methodology for matching objects to specific firearms» that lend themselves to varying interpretations or lack explicit requirements regarding examination conditions. A newly proposed algorithm is easy to apply in forensic practice and can be recommended as a supplement to the methodology in question.Разъясняются некоторые положения «Методики установления принадлежности объекта к огнестрельному оружию», допускающие неоднозначное толкование или нечеткие требования к условиям проведения исследования. Предложен алгоритм, легко применимый в экспертной практике и рекомендованный в качестве дополнения к указанной методике

The Design Optimization and Experimental Investigation of the 4.4 μm Raman Laser Basedon Hydrogen-filled Revolver Silica Fiber

Optical properties of hollow-core revolver fibers are numerically investigated depending on various parameters: the hollow-core diameter, the capillary wall thickness, the values of the minimum gap between the capillaries, the number of capillaries in the cladding and the type of glass (silica and chalcogenide). Preliminary, similar calculations are made for simple models of hollow-core fibers. Based on the obtained results, the optimal design of the revolver fiber for Raman laser frequency conversion (1.56 μm → 4.4 μm in 1H2) was determined. As a result, efficient ns-pulsed 4.42 μm Raman laser based on 1H2-filled revolver silica fiber is realized. Quantum efficiency as high as 36 % is achieved and output average power as high as 250 mW is demonstrated