Influence of Phase Diffuser Dynamics on Scintillations of Laser Radiation in Earth Atmosphere: Long-Distance Propagation

The effect of a random phase diffuser on fluctuations of laser light (scintillations) is studied. Not only spatial but also temporal phase variations introduced by the phase diffuser are analyzed. The explicit dependence of the scintillation index on finite-time phase variations is obtained for long propagation paths. It is shown that for large amplitudes of phase fluctuations, a finite-time effect decreases the ability of phase diffuser to suppress the scintillations.Comment: 15 pages, 4 figure

The formation and development trends of the consulting market in Russia

© 2015, Mediterranean Center of Social and Educational Research. All rights reserved. In the conditions of rapid growth of service industries and, above all, business services, the importance of advisory services (consulting) is steadily enhancing for the domestic economy and the growth of its competitiveness. The article analyzes the basic processes occurring in the modern Russian market of consulting services, the trends and patterns of its development, including the growing processes of concentration and centralization, the underdevelopment of market institutions, the lack of legislation regulating this market segment, structural defects associated with the excessive income growth of the management consulting. All this allowed us to draw some important conclusions about the unstable and contradictory nature of the development of the domestic market of consulting, the deformation of its structure and the absence of the state policy in the sphere of regulation of the consulting services market, and to develop recommendations for its stabilization, including the improvement of legislation in the field of intellectual property, the expansion and strengthening of the foreign economic positions of the consulting companies in Russia, the efficiency improvement of their participation in the international division of labor. The article is intended for students studying methods of conducting marketing research on the market of consulting services, teachers of the discipline "Marketing in services", "Consulting" as well as for marketing managers and managers of consulting companies elaborating strategies for their development

Tomosyn inhibits synaptic vesicle priming in Caenorhabditis elegans

Caenorhabditis elegans TOM-1 is orthologous to vertebrate tomosyn, a cytosolic syntaxin-binding protein implicated in the modulation of both constitutive and regulated exocytosis. To investigate how TOM-1 regulates exocytosis of synaptic vesicles in vivo, we analyzed C. elegans tom-1 mutants. Our electrophysiological analysis indicates that evoked postsynaptic responses at tom-1 mutant synapses are prolonged leading to a two-fold increase in total charge transfer. The enhanced response in tom-1 mutants is not associated with any detectable changes in postsynaptic response kinetics, neuronal outgrowth, or synaptogenesis. However, at the ultrastructural level, we observe a concomitant increase in the number of plasma membrane-contacting vesicles in tom-1 mutant synapses, a phenotype reversed by neuronal expression of TOM-1. Priming defective unc-13 mutants show a dramatic reduction in plasma membrane-contacting vesicles, suggesting these vesicles largely represent the primed vesicle pool at the C. elegans neuromuscular junction. Consistent with this conclusion, hyperosmotic responses in tom-1 mutants are enhanced, indicating the primed vesicle pool is enhanced. Furthermore, the synaptic defects of unc-13 mutants are partially suppressed in tom-1 unc-13 double mutants. These data indicate that in the intact nervous system, TOM-1 negatively regulates synaptic vesicle priming. © 2006 Gracheva et al

Optimized sensorless control systems for cargo movement mechanisms

THE PURPOSE. Investigation of the control system of the cargo movement mechanism when using different variants of sensorless control. The search for the optimal option, in which the formation of the speed is identical to the data obtained from the speed sensor. Analysis of the results obtained during the study, including the results obtained taking into account the heating of the motor windings. METHODS. The tasks set during the research are implemented by simulation modeling using the Matlab Simulink computer simulation environment. RESULTS. The article considers systems with different types of velocity observers. A system is implemented that takes into account the heating of the stator and rotor windings of an asynchronous motor, in which a non-adaptive observer and different types of neural network controller were introduced. A combined method of using neural network regulators is proposed. CONCLUSION. Sensorless control systems are relevant for use in industries with the presence, according to the conditions of the technological process, of high temperatures. The conducted research has shown that the use of neural network technologies allows you to work with settings of different levels and types. The proposed method, implying the use of joint work of neural network observers with various neurostructures, allows for speed testing in the entire range. The connection with cloud storage present in the proposed structure leads to the unloading of the management system, allowing to increase the process of analyzing data coming from the object.publishe

Experimental manifestations of the Nb^{4+}-O^{-} polaronic excitons in KTa_{0.988}Nb_{0.012}O_{3}

The formation of the photo-polaronic excitons in ABO_{3} perovskite type oxides has been detected experimentally by means of the photoinduced electron paramagnetic resonance studies of KTa_{0.998}Nb_{0.012}O_{3} crystals. The corresponding microwave X-band spectrum at T < 10 K consists of a narrow, nearly isotropic signal located at g ~ 2 and a strongly anisotropic component. The first signal, which has a rich structure due to hyperfine interactions with the lattice nuclei, is attributed to the single trapped charge carriers: the electrons and/or the holes. The anisotropic spectrum is caused by the axial centers oriented along the C_{4} pseudo-cubic principal crystalline axes. The spectrum angular dependence can be described well by an axial center with S = 1, g_{\parallel) = 0.82, g_{\perp} = 0.52 and D = 0.44 cm^{-1}. The anisotropic spectrum is attributed to the Nb^{4+}-O^{-} polaronic excitons. The temperature dependence of the anisotropic component is characterized by two activation energies: the internal dynamics activation E_{a1} = 3.7\pm0.5 meV, which makes the EPR spectrum unobservable above 10 K, and the destruction energy E_{a2} = 52\pm4 meV. By comparing the anisotropic photo-EPR spectrum and the photoinduced optical absorption temperature dependencies, we found that the Nb^{4+}-O^{-} polaronic excitons also manifested themselves via the ~0.7 eV wide absorption band arising under UV light excitation in the weakly concentrated KTaO_{3}:Nb crystals.Comment: PDF, 15 pages, 6 figures (submitted to Physical review B

Structure changes in InP and GaAs crystals double irradiated with electrons and swift heavy ions

We have studied InP and GaAs crystal structure changes under the influence of swift Kr and Bi ions irradiation by means of scanning electron microscopy, atomic force microscopy and selective chemical etching. The previous disordering of samples by electron irradiation is shown to be leading to macrodefect formation in the form of cracks and breaks at the depths near the ion end-of-range and on the crystal surface. A possible explanation of the observed effects is proposed.Вивчено вплив змін структури ІnP і GaAs при опроміненні іонами Kr і Bі й електронами при вивченні методом електронної мікроскопії, атомної силової мікроскопії й сективного хімічного травлення. Основними ефектами при цьому впливі були утворення тріщин і руйнувань структури поверхні, які найбільше значно проявлялися наприкінці пробігу іонів і поблизу поверхні. Можливе пояснення виявлених ефектів представлено.Изучено влияние изменений структуры InP- и GaAs- при облучении ионами Kr и Bi и электронами при изучении методом электронной микроскопии, атомной силовой микроскопии и сективного химического травления. Основными эффектами при этом воздействии являлись образование трещин и разрушений структуры поверхности, которые наиболее значительно проявлялись в конце пробега ионов и вблизи поверхности. Возможное объяснение обнаруженных эффектов представлено

Experimental manifestations of the Nb4+-O- polaronic excitons in KTa0.988Nb0.012O3

The formation of the photopolaronic excitons in ABO3 perovskite-type oxides has been detected experimentally by means of the photoinduced electron paramagnetic resonance (EPR) studies of KTa 0.988Nb0.012O3 crystals. The corresponding microwave x-band spectrum at T< 10 K consists of a narrow, nearly isotropic signal located at g ∼ 2 and a strongly anisotropic component. The first signal, which has a rich structure due to hyperfine interactions with the lattice nuclei, is attributed to the single trapped charge carriers: the electrons and/or the holes. The anisotropic spectrum is caused by the axial centers oriented along the C4 pseudocubic principal crystalline axes. The spectrum angular dependence can be described well by an axial center with S = 1, g = 0.82, g = 0.52, and D = 0.44 cm-1. The anisotropic spectrum is attributed to the Nb4+-O- polaronic excitons. The temperature dependence of the anisotropic component is characterized by two activation energies: the internal dynamics activation Ea1 = 3.7 ± 0.5 meV, which makes the EPR spectrum unobservable above 10K, and the destruction energy Ea2 = 52 ± 4 meV. By comparing the anisotropic photo-EPR spectrum and the photoinduced optical absorption temperature dependencies, we found that the Nb4+-O - polaronic excitons also manifested themselves via the wide absorption band at ∼0.7 eV arising under ultraviolet light excitation in the weakly concentrated KTaO3:Nb crystals. © 2011 American Physical Society

Antioxidative vs cytotoxic activities of organotin complexes bearing 2,6-di-tert-butylphenol moieties

Copyright © 2018 John Wiley & Sons, Ltd. Two series of organotin(IV) complexes with Sn–S bonds on the base of 2,6-di-tert-butyl-4-mercaptophenol (L1SH) of formulae Me2Sn(L1S)2 (1); Et2Sn(L1S)2 (2); Bu2Sn(L1S)2 (3); Ph2Sn(L1S)2 (4); (L1)2Sn(L1S)2 (5); Me3Sn(L1S) (6); Ph3Sn(L1S) (7) (L1 = 3,5-di-tert-butyl-4-hydroxyphenyl), together with the new ones [Me3SnCl(L2)] (8), [Me2SnCl2(L2)2] (9) (L2 = 2-(N-3′,5′-di-tert-butyl-4′-hydroxyphenyl)-iminomethylphenol) were used to study their antioxidant and cytotoxic activity. Novel complexes 8, 9 of MenSnCl4 − n (n = 3, 2) with Schiff base were synthesized and characterized by 1H, 13C NMR, IR and elemental analysis. The crystal structures of compounds 8 and 9 were determined by X-ray diffraction analysis. The distorted tetrahedral geometry around the Sn center in the monocrystals of 8 was revealed, the Schiff base is coordinated to the tin(IV) atom by electrostatic interaction and formation of short contact Sn–O 2.805 Å. In the case of complex 9 the distorted octahedron coordination of Sn atom is formed. The antioxidant activity of compounds as radical scavengers and reducing agents was proved spectrophotometrically in tests with stable radical DPPH, reduction of Cu2+ (CUPRAC method) and interaction with superoxide radical-anion. Moreover, compounds have been screened for in vitro cytotoxicity on eight human cancer cell lines. A high activity against all cell lines with IC50 values 60–160 nM was determined for the triphenyltin complex 7, while the introduction of Schiff base decreased the cytotoxicity of the complexes. The influence on mitochondrial potential and mitochondrial permeability for the compounds 8 and 9 has been studied. It is shown that studied complexes depolarize the mitochondria but don't influence the calcium-induced mitochondrial permeability transition

A Mathematical Model of Liver Cell Aggregation In Vitro

The behavior of mammalian cells within three-dimensional structures is an area of intense biological research and underpins the efforts of tissue engineers to regenerate human tissues for clinical applications. In the particular case of hepatocytes (liver cells), the formation of spheroidal multicellular aggregates has been shown to improve cell viability and functionality compared to traditional monolayer culture techniques. We propose a simple mathematical model for the early stages of this aggregation process, when cell clusters form on the surface of the extracellular matrix (ECM) layer on which they are seeded. We focus on interactions between the cells and the viscoelastic ECM substrate. Governing equations for the cells, culture medium, and ECM are derived using the principles of mass and momentum balance. The model is then reduced to a system of four partial differential equations, which are investigated analytically and numerically. The model predicts that provided cells are seeded at a suitable density, aggregates with clearly defined boundaries and a spatially uniform cell density on the interior will form. While the mechanical properties of the ECM do not appear to have a significant effect, strong cell-ECM interactions can inhibit, or possibly prevent, the formation of aggregates. The paper concludes with a discussion of our key findings and suggestions for future work