437 research outputs found
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
ΠΠ°ΡΠ΅Π΄Π°Π½ΠΈΠ΅ ΡΠ°Π±ΠΎΡΠ΅ΠΉ Π³ΡΡΠΏΠΏΡ ENFSI ΠΏΠΎ ΡΡΠ΄Π΅Π±Π½ΠΎ- Π±Π°Π»Π»ΠΈΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΊΡΠΏΠ΅ΡΡΠΈΠ·Π΅ (ΠΡΠΏΠΎΠΎ, Π€ΠΈΠ½Π»ΡΠ½Π΄ΠΈΡ)
The paper reports on the outcomes of the 24th Annual Meeting of the Firearms/GSR ExpertΒ Working Group of the European Network of Forensic Science Institutes (ENFSI) that was held inΒ October 2017 in Finland.ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Ρ ΠΈΡΠΎΠ³ΠΈ 24-ΠΉ Π΅ΠΆΠ΅Π³ΠΎΠ΄Π½ΠΎΠΉ Π²ΡΡΡΠ΅ΡΠΈ ΡΠ°Π±ΠΎΡΠ΅ΠΉ Π³ΡΡΠΏΠΏΡ ΠΠ²ΡΠΎΠΏΠ΅ΠΉΡΠΊΠΎΠΉ ΡΠ΅ΡΠΈΒ ΡΡΠ΄Π΅Π±Π½ΠΎ-ΡΠΊΡΠΏΠ΅ΡΡΠ½ΡΡ
ΡΡΡΠ΅ΠΆΠ΄Π΅Π½ΠΈΠΉ (ENFSI) ΠΏΠΎ ΡΡΠ΄Π΅Π±Π½ΠΎ-Π±Π°Π»Π»ΠΈΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΊΡΠΏΠ΅ΡΡΠΈΠ·Π΅, ΠΏΡΠΎΡΠ΅Π΄ΡΠ΅ΠΉ Π²Β ΠΎΠΊΡΡΠ±ΡΠ΅ 2017 Π³ΠΎΠ΄Π° Π² Π€ΠΈΠ½Π»ΡΠ½Π΄ΠΈ
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
Π Π°Π·ΡΡΡΠ½Π΅Π½ΠΈΠ΅ Π½Π΅ΠΊΠΎΡΠΎΡΡΡ ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠΈ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ ΠΏΡΠΈΠ½Π°Π΄Π»Π΅ΠΆΠ½ΠΎΡΡΠΈ ΠΎΠ±ΡΠ΅ΠΊΡΠ° ΠΊ ΠΎΠ³Π½Π΅ΡΡΡΠ΅Π»ΡΠ½ΠΎΠΌΡ ΠΎΡΡΠΆΠΈΡ
The paper clarifies some of the provisions of the Β«Methodology for matching objects to specific firearmsΒ» 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.Π Π°Π·ΡΡΡΠ½ΡΡΡΡΡ Π½Π΅ΠΊΠΎΡΠΎΡΡΠ΅ ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΡ Β«ΠΠ΅ΡΠΎΠ΄ΠΈΠΊΠΈ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ ΠΏΡΠΈΠ½Π°Π΄Π»Π΅ΠΆΠ½ΠΎΡΡΠΈ ΠΎΠ±ΡΠ΅ΠΊΡΠ° ΠΊ ΠΎΠ³Π½Π΅ΡΡΡΠ΅Π»ΡΠ½ΠΎΠΌΡ ΠΎΡΡΠΆΠΈΡΒ», Π΄ΠΎΠΏΡΡΠΊΠ°ΡΡΠΈΠ΅ Π½Π΅ΠΎΠ΄Π½ΠΎΠ·Π½Π°ΡΠ½ΠΎΠ΅ ΡΠΎΠ»ΠΊΠΎΠ²Π°Π½ΠΈΠ΅ ΠΈΠ»ΠΈ Π½Π΅ΡΠ΅ΡΠΊΠΈΠ΅ ΡΡΠ΅Π±ΠΎΠ²Π°Π½ΠΈΡ ΠΊ ΡΡΠ»ΠΎΠ²ΠΈΡΠΌ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ Π°Π»Π³ΠΎΡΠΈΡΠΌ, Π»Π΅Π³ΠΊΠΎ ΠΏΡΠΈΠΌΠ΅Π½ΠΈΠΌΡΠΉ Π² ΡΠΊΡΠΏΠ΅ΡΡΠ½ΠΎΠΉ ΠΏΡΠ°ΠΊΡΠΈΠΊΠ΅ ΠΈ ΡΠ΅ΠΊΠΎΠΌΠ΅Π½Π΄ΠΎΠ²Π°Π½Π½ΡΠΉ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π΄ΠΎΠΏΠΎΠ»Π½Π΅Π½ΠΈΡ ΠΊ ΡΠΊΠ°Π·Π°Π½Π½ΠΎΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ΅
The Design Optimization and Experimental Investigation of the 4.4 ΞΌm 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 ΞΌm β 4.4 ΞΌm in 1H2) was determined. As a result, efficient ns-pulsed 4.42 ΞΌm 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
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