A coherent fiber-optic transmission systems of OFDM signals is considered. The channels are formed using spectral-efficient modulation formats (QPSK and M-QAM). The influence of nonlinear phase noise ...arising in an optical fiber on channel signals is studied. It is shown that nonlinear phase noise appearing in the optical path is converted into amplitude noise and, mixing with the noise of optical amplifiers, leads to a decrease in the signal quality factor. Estimation formulas for determining the noise immunity of channel signals by calculating the Q-factor are given.
The results of experimental observation of coherent Cherenkov radiation from picosecond electron bunches traveling along the axis of a dielectric loaded cylindrical waveguide are presented. ...Experiments have been performed at the AREAL linear accelerator at the CANDLE Synchrotron Research Institute. The angular distribution of radiation from 3.7 MeV electron bunches passing through cylindrical quartz sample is investigated. In the second part of the paper we argue that, by tuning the ratio of the distance between the bunches crossing the plate inside the waveguide and the radius of the waveguide, one can further increase the intensity of quasi-coherent Cherenkov radiation on several neighboring modes.
The review presents the history of the creation and work of the Scientific Council “Cybernetics” (SCC)—the center for development of cybernetics in the USSR and Russia. The Council’s activity is ...covered as a structure that coordinates scientific and technical activity in cybernetics in the country via a system of sections: about 16 public and professional bodies involving thousands of specialists. Brief information about the sections is given. The chronology of development of the SCC is discussed, in particular, information about its chairmen, starting with the renowned organizer of research and development, Academician and Admiral Axel Ivanovich Berg and the following academicians: B.N. Petrov, O.M. Belotserkovsky, A.P. Ershov, E.P. Velikhov, B.V. Bunkin, and Yu.I. Zhuravlev. The SCC’s publishing activity is briefly reviewed. The second function, built into the SCC from its onset, is as a research institute conducting its own research on the most pressing scientific problems insufficiently covered by existing structures. Several main areas of research by the SCC itself and its successor, the Axel Berg Institute of Cybernetics and Educational Computing of the Federal Research Center “Computer Science and Control” of the RAS: coding and transmission of information, economic cybernetics, aircraft control, supercomputers, digital technologies in education, mathematical logic and the theory of algorithms, pattern recognition and image analysis, mathematical methods of image analysis, theoretical physics, biomedical cybernetics, and ultrasound imaging. Another function of the SCC is considered: as an incubator of new academic industrially oriented structures and the fate of one of them—the Institute of Cybernetics Problems—is traced.
A technique is proposed for estimating the signal-to-noise ratio in fiber-optic transmission systems with spectral multiplexing, multiplexing of orthogonal and non-orthogonal channel subcarriers in ...the case of cross-channel interference due to four-wave mixing in the fiber. It is shown that it is possible to estimate the signal-to-noise ratio of a system with any number of sub-carriers of channels from the results of measurements of this ratio for a four-channel transmission system.
Advanced Research Electron Accelerator Laboratory (AREAL) is a 50MeV electron linear accelerator project with a laser driven RF gun being constructed at the CANDLE Synchrotron Research Institute. In ...addition to applications in life and materials sciences, the project aims as a test facility for advanced accelerator and radiation source concepts. In this paper, the AREAL RF photoinjector performance, the facility design considerations and its highlights in the fields of free electron laser, the study of new high frequency accelerating structures, the beam microbunching and wakefield acceleration concepts are presented.
In this paper we consider nonlinear oscillations of an isotropic cylindrical shallow shell in a supersonic gas flow. The study is carried out with considering both types of nonlinearity: the ...geometric and the aerodynamic. By taking into account the asymmetric (quadratic) nonlinearity, we come to a conclusion that in certain velocity intervals the amplitude-velocity dependence is a multi-valued function. It is shown, that there exist so-called zones of silence - the intervals of the steaming flow velocity, where undamped flutter oscillations cannot be induced. Here we give some of our most important and significant results, which follow from the influence of a supersonic gas flow on the nature of nonlinear oscillations of the investigated aeroelastic system: a) the larger the relative radius of the shell, the wider the silence zone; b) the amplitude of oscillations, depending on the flow velocity, is a monotonously decreasing function in the region to the left of the silence zone and tends to zero at the left boundary of the zone; at the right boundary of the zone the amplitude increases abruptly to a certain finite value and then it monotonously decreases; c) in the case of thin shells with an increase in the velocity of the flow we observe the following: flutter oscillations mode persists up to a certain velocity value (the "upper" critical velocity), where the oscillations "break off" and the unperturbed state of the shell restores. When the velocity decreases, the unperturbed state is stable as long as the velocity is greater than the critical flutter velocity (the "lower" critical velocity), at which the amplitude of flutter oscillations increases abruptly to a certain value and keeps increasing with further velocity decrease; d) in the case of sufficiently thin shells, the zone of silence is a semi-infinite region.
Chemical, X-ray diffraction, and IR spectroscopic analyses of rocks (perlites, zeolites, and tuffs) and specimens based on them are performed to identify the processes that occur during thermal ...processing that leads to the syntheses of various materials. The syntheses are performed by microwave treatment in the range from 90 to 600 W with different exposure times. Materials are developed, and heat-treatment regimes and location for each type of mineral filler are determined.
The mathematical model for estimating a standard deviation of beat interference generated during photodetection of subcarrier signals with QPSK and M-QAM modulation formats is considered. The theory ...and the results of computer simulation are used to derive a formula for calculating the spectral distribution of beat interference depending on the number of signals and used modulation formats.
Reducing fuel cells electrical losses is achieved by the use of a catalyst. Being inexpensive and renewable, biocathodes have an advantage over synthetic and chemical ones. Here the microbial fuel ...cell (MFC)-utilizing biocathode based on the acidophilic chemolythotrophic microorganisms (ACM) mixed culture has been studied. The Leptospirillum sp., Acidithiobacillus sp., Ferroplasma sp. consortium has been used as a cathode biocatalyst. Pyrite enrichment tails of a mining and processing enterprise served as the catholyte substrates. It is experimentally demonstrated that ACM mixed culture Leptospirillum sp., Acidithiobacillus sp., Ferroplasma sp. introduced into the catholyte leads to MFC electrical characteristics increase by approximately two times. With the selected external load (30 Ω) Cathodic bioagents increased the MFC electric power four-fold (from 137 to 579 µW). Catholyte redox potential increased from 431 to 581 mV during 11 d in the presence of acidophilic iron-oxidizing microorganisms. At 33 d, this value increased up to 695 mV. This is an indirect evidence for active processes of iron oxidation. The analysis results for the Fe
3+
content in the medium also support this assumption. Thus, in a course of a 33-d experiment Fe
3+
concentration increased from 0 to 1.5 g/l. The redox processes intensification in the studied systems also confirmed by the cyclic voltammetry (CV). Under pyrite utilization conditions in the presence of ACM mixed culture cyclic voltammograms show an increase in the reduction current at the cathodic potentials region. The results obtained herein suggest that the studied biochemical system is a perspective catholyte for MFC capable to reduce a cathodic overpotential.
Aim . The aim of our study was to investigate the influence of polymorphic markers of CYP3A4*22 CYP3A4*22 ( c.522-191C>T, rs35599367 ), CYP3A5*3 ( c.219 237A>G, rs776746 ), ABCB1 rs1045642 ( ...c.3435T>C ) and rs4148738 ( c.2692-2236C>T ) genes on the plasma concentration of apixaban, on changes in prothrombin time (PT), activated partial thromboplastin time (APTT), and bleeding development in patients taking apixaban. Material and methods. The study included 108 patients with non-valvular atrial fibrillation and deep vein thrombosis receiving apixaban in therapeutic doses. Genotyping was performed by real-time polymerase chain reaction. Apixaban concentrations were measured using an electrospray ionization mass spectrometer in positive ionization mode. Because the daily dose of apixaban was different (5, 10, and 20 mg daily), the residual equilibrium concentration (Cmin,ss) of apixaban was adjusted relative to the daily drug dose (Cmin,ss/D). PT and APTT were determined using an automatic coagulometer analyzer Destiny Max (Tcoag, Ireland). Statistical processing was performed in SPSS Statistics 20.0 program. Results . We found that patients with CT ABCB1 ( rs4148738 ) C>T genotype had higher Cmin,ss /D value than patients with TT genotype (6.23 4;13 vs 5.77 4;17, p=0.018). No statistically significant associations were found between carriage of CYP3A4*22 (rs35599367) C>T, CYP3A5*3 A>G, ABCB1 (rs1045642) C>T gene polymorphisms and Cmin,ss /D value of apixaban. Also, there was no significant effect of carrying polymorphisms rs35599367, rs776746, rs4148738,rs4148642, and the above genes on the risks of hemorrhagic complications. However, the influence of ABCB1 (rs1045642) C>T polymorphism on the PT value was found ( TT ABCB1 ( rs1045642 ) C>T genotype carriers the CT value wassignificantly higher than in CT genotype (17.0 40;112 vs. 14.9 35;132) p=0.044). Conclusion . It was found that the Cmin,ss /D value was higher in patients with CT ABCB1 (rs4148738) C>T genotype than in patients with TT genotype. At the same time, carriage of polymorphisms of CYP3A4*22 (rs35599367) C>T , CYP3A5*3 A>G , ABCB1 (rs1045642) C>T genes did not affect the pharmacokinetics of apixaban and the risk of bleeding. We also identified the effect of ABCB1 (rs1045642) C>T gene polymorphism on the PT value.
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