410 research outputs found
Landau damping in thin films irradiated by a strong laser field
The rate of linear collisionless damping (Landau damping) in a classical
electron gas confined to a heated ionized thin film is calculated. The general
expression for the imaginary part of the dielectric tensor in terms of the
parameters of the single-particle self-consistent electron potential is
obtained. For the case of a deep rectangular well, it is explicitly calculated
as a function of the electron temperature in the two limiting cases of specular
and diffuse reflection of the electrons from the boundary of the
self-consistent potential. For realistic experimental parameters, the
contribution of Landau damping to the heating of the electron subsystem is
estimated. It is shown that for films with a thickness below about 100 nm and
for moderate laser intensities it may be comparable with or even dominate over
electron-ion collisions and inner ionization.Comment: 15 pages, 2 figure
Key schedule based on a modified additive generator
A method of round key generation for iterated block ciphers based on a modified additive generator (MAG), and, in addition, on MAG and a linear congruent generator in a series circuit is proposed. The bijectivity of the generating transformation is demonstrated. Using the matrix-graph approach the number of iterations necessary for achieving enhanced cryptographic properties is experimentally evaluated. This number depends on the generator characteristics
Investigation converter circuit "voltage-current" for power calibrator
The paper presents alternative circuits for voltage-current converters to be used in the calibrator of fictitious power. The experimental studies have revealed a number of problems related to the stability of the system in deep feedback and zero level stabilization of the amplifier. The circuit solutions given in the article allow elimination of these problems and improve the accuracy of calibrator current calibration. For example, correction/corrective circuits are used to ensure the stability of the converter at deep depths of the feedback, and operational amplifier based circuit solution and compensation condition are proposed to reduce the additional phase shift. To improve the accuracy of the calibration current values specified by the calibrator we propose to connect the feedback circuit to the measuring current transformer. However, further improvement of the accuracy class of the power calibrator is impossible without modern electronic components
European regional conflicts of the second half of the 1930s and the evolution of the national-socialist Image of enemy
Regional conflicts in West and Central Europe, in the second half of the 1930s symbolized the collapse of the Versailles system, olarizing the situation and affecting the balance of power on the continent. All of them had international aspects, including propaganda aspect. European regional conflicts (1936-1939) have become a convenient case for approbation of the "old" Nazi ideological postulates as well as for development of "new" one
LONG-TERM RESULTS OF TRANSMYOCARDIAL LASER REVASCULARIZATION COMBINED WITH IMPLANTATION OF AUTOLOGOUS BONE MARROW MONONUCLEAR FRACTION IN THE TREATMENT OF CHRONIC ISCHEMIC HEART DISEAS
Aim. Clinical and instrumental assessment of long-term results of autologous bone marrow cells (BMC) implantation in laser channels in surgery of ischemic heart disease with diffuse and distal coronary disease.Materials and Methods. In the period of 2007–2008 35 CHD patients with diffuse and distal coronary disease underwent BMC implantation in laser channels during coronary artery bypass grafting (CABG). The control group consisted of 29 patients. All patients in this group underwent only direct myocardial revascularization (DMR). In the long-term period we examined only 30 patients of the first group. Clinical and instrumental assessment of the method efficacy was carried out in 2 weeks, 6 months and 6 years after surgery.Results. FC (NYHA) mean value in indirect revascularization group significantly decreased from 2.57 ± 0.61 preoperatively to 1.77 ±0.66 in6 months after surgery (p = 0.043). After 6 years FC (NYHA) was not significantly changed – 1.84 ± 0.42 (p = 0.053). Perfusion scintigraphy revealed a slight decrease of stable perfusion defect (SPD) in the immediate postoperative period, a more pronounced reduction of SPD in 6 months after surgery. The average value of SPD before surgery was 20.46 ± 10.75%, in 2 weeks after the operation – 19.07 ± 9.69%, in 6 months after surgery – 15.22 ± 9.49%. In the long-term period (6 years) SPD was 14.8 ± 8.43% (p = 0.047). A similar pattern was observed in the analysis of transient perfusion defect: baseline – 30 ± 2.2%, in 6 months – 15 ± 1.3%, in the long term period – 20 ± 6.1% (p = 0.047). The average value of left ventricular ejection fraction (LVEF) before surgery was 55 ± 10.4%, in 2 weeks after the operation – 55.7 ± 9.3%, in 6 months – 56.7 ± 10%, after 6 years – 54 ± 12%. The dynamics is unauthentic (p = 0.068).Conclusion. BMC implantation in laser channels in addition to CABG is a safe and effective method of surgical treatment in case of CABG inability. The effect of indirect revascularization is formed in the first 6 months after surgery and remains at the same level for 6 years
Stratospheric warming influence on the mesosphere/lower thermosphere as seen by the extended CMAM
The response of the upper mesosphere/lower thermosphere region to major
sudden stratospheric warming (SSW) is examined employing temperature, winds,
NOX and CO constituents from the extended Canadian Middle
Atmosphere Model (CMAM) with continuous incremental nudging below 10 hPa
(~ 30 km). The model results considered cover high latitudes
(60–85° N) from 10 to 150 km height for the December–March period
of 2003/2004, 2005/2006 and 2008/2009, when some of the strongest SSWs in
recent years were observed. NOX and CO are used as proxies for
examining transport. Comparisons with ACE-FTS (Atmospheric Chemistry Experiment–Fourier Transform Spectrometer) satellite observations show
that the model represents well the dynamics of the upper mesosphere/lower
thermosphere region, the coupling of the stratosphere–mesosphere, and the
NOX and CO transport. New information is obtained on the upper
mesosphere/lower thermosphere up to 150 km showing that the NOX
volume mixing ratio in the 2003/2004 winter was very perturbed indicating
transport from the lower atmosphere and intense mixing with large
NOX influx from the thermosphere compared to 2006 and 2009. These
results, together with those from other models and observations, clearly show
the impact of stratospheric warmings on the thermosphere
Three-body correlations in direct reactions: Example of Be populated in reaction
The Be continuum states were populated in the charge-exchange reaction
H(Li,Be) collecting very high statistics data ( events) on the three-body ++ correlations. The
Be excitation energy region below MeV is considered, where the
data are dominated by contributions from the and states. It is
demonstrated how the high-statistics few-body correlation data can be used to
extract detailed information on the reaction mechanism. Such a derivation is
based on the fact that highly spin-aligned states are typically populated in
the direct reactions.Comment: submitted to Physical Review
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