1,021 research outputs found
Heat transfer in a one-dimensional harmonic crystal in a viscous environment subjected to an external heat supply
We consider unsteady heat transfer in a one-dimensional harmonic crystal
surrounded by a viscous environment and subjected to an external heat supply.
The basic equations for the crystal particles are stated in the form of a
system of stochastic differential equations. We perform a continualization
procedure and derive an infinite set of linear partial differential equations
for covariance variables. An exact analytic solution describing unsteady
ballistic heat transfer in the crystal is obtained. It is shown that the
stationary spatial profile of the kinetic temperature caused by a point source
of heat supply of constant intensity is described by the Macdonald function of
zero order. A comparison with the results obtained in the framework of the
classical heat equation is presented. We expect that the results obtained in
the paper can be verified by experiments with laser excitation of
low-dimensional nanostructures.Comment: 12 pages, 5 figure
Institutional and organizational features of cross-border cargo traffic in the post-soviet space integration terms. Part I
The article covers the technical, technological, institutional, and organizational barriers of cross-border transportation of cargo. The study uses an institutional approach as a methodological alternative to other approaches. The study touches on institutional and organizational problems of border crossing checkpoints arrangement, the consequences of the application of unified transport documents and the introduction of electronic communication forms. Particular attention is paid to the analysis of demonstrative actions and the daily practice of reducing the time of customs procedures and reducing transaction costs of cross-border cargo traffic. Herewith it is indicated that the most effective way to improve the efficiency of cross-border transportation of cargo suggests simultaneous implementation of technical and institutional innovations. Emphasis is placed on identifying the institutional and organizational features of the international road transportation of cargo, in particular, the problems of the evolution of the guaranteed customs duties payment institute, the permission system in the implementation of cross-border cargo traffic. The fact that the state support of national entrepreneurs requires a mechanism to ensure the parity of Russian and foreign carriers, at least in the field of cargo transportation for state needs, with the involvement of credit resources of government-linked banks is highlighted. It is underlined that the first step towards improving the institutional environment of international road transportation should envisage the elimination of all informal (shadow) relations in this sphere. The article identifies institutional features of cargo transportation in specific areas such as deliveries by road to China through Kazakhstan, and the challenges and prospects for the use and development of transit potential of Kaliningrad Region. The article shows institutional and organizational characteristics of combined transportation in cross-border traffic. The article concludes that the development of cross-border transportation of cargo and the implementation of transport and transit potential of EAEU member states may and should become a powerful source of income for business entities, budgets of all levels and households, as well as the driving force of industrial and technological upgrading and institutional and organizational evolution of economic systems of the countries and integration associations.The article has been prepared with the support of the Russian Foundation for Basic Research (Project β 15-06-06939 a Β«Modelling the cyclical evolution of mutual influence of the national transport system and the state of the markets of goods (services), labor and capital in terms of integration and global instabilityΒ»)
Π’ΠΎΠ½Π·ΠΈΠ»Π΅ΠΊΡΠΎΠΌΠΈΡ β ΡΡΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΠΈ ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠ²Π½ΠΈ ΡΠ΅Ρ Π½ΠΈΠΊΠΈ
Π¦Π΅Π»ΡΠ° Π½Π° Π½Π°ΡΡΠΎΡΡΠ°ΡΠ° ΡΡΠ°ΡΠΈΡ Π΅ Π΄Π° ΡΠ΅ Π½Π°ΠΏΡΠ°Π²ΠΈ ΡΡΠ°Π²Π½ΠΈΡΠ΅Π»Π½ΠΎ ΠΊΠ»ΠΈΠ½ΠΈΡΠ½ΠΎ ΠΈΠ·ΡΠ»Π΅Π΄Π²Π°Π½Π΅ Π½Π° ΡΡΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΠΈΡΠ΅ ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠ²Π½ΠΈ ΡΠ΅Ρ
Π½ΠΈΠΊΠΈ ΠΈ ΠΊΠΎΠ½Π²Π΅Π½ΡΠΈΠΎΠ½Π°Π»Π½Π°ΡΠ° ΡΠΎΠ½Π·ΠΈΠ»Π΅ΠΊΡΠΎΠΌΠΈΡ. ΠΠ° ΠΏΠ΅ΡΠΈΠΎΠ΄ ΠΎΡ Π΄Π²Π΅ Π³ΠΎΠ΄ΠΈΠ½ΠΈ Π² Π£ΠΠ-ΠΊΠ»ΠΈΠ½ΠΈΠΊΠ°ΡΠ° Π½Π° ΠΠΠ β Π‘ΠΎΡΠΈΡ Π±ΡΡ
Π° ΠΈΠ·Π²ΡΡΡΠ΅Π½ΠΈ 176 ΡΠΎΠ½Π·ΠΈΠ»Π΅ΠΊΡΠΎΠΌΠΈΠΈ Π½Π° Π±ΠΎΠ»Π½ΠΈ Π½Π° Π²ΡΠ·ΡΠ°ΡΡ ΠΎΡ 10 Π΄ΠΎ 45 Π³ΠΎΠ΄ΠΈΠ½ΠΈ. ΠΡ ΡΡΡ
45% Π±ΡΡ
Π° ΠΎΠΏΠ΅ΡΠΈΡΠ°Π½ΠΈ ΠΊΠΎΠ½Π²Π΅Π½ΡΠΈΠΎΠ½Π°Π»Π½ΠΎ, ΠΏΡΠΈ 35% Π±Π΅ ΠΈΠ·ΠΏΠΎΠ»Π·Π²Π°Π½ ΡΠ»ΡΡΠ°Π·Π²ΡΠΊΠΎΠ² Ρ
Π°ΡΠΌΠΎΠ½ΠΈΡΠ΅Π½ ΡΠΊΠ°Π»ΠΏΠ΅Π» Ultracision, Π° ΠΏΡΠΈ ΠΎΡΡΠ°Π½Π°Π»ΠΈΡΠ΅ 20% Π±Π΅ ΠΈΠ·ΠΏΠΎΠ»Π·Π²Π°Π½ ΡΠ°Π΄ΠΈΠΎΡΠ΅ΡΡΠΎΡΠ΅Π½ Π°ΠΏΠ°ΡΠ°Ρ Coblator.Π Π΅Π·ΡΠ»ΡΠ°ΡΠΈΡΠ΅ ΠΏΠΎΠΊΠ°Π·Π°Ρ
Π° ΡΡΠ²ΡΡΠ²ΠΈΡΠ΅Π»Π½Π° ΡΠ°Π·Π»ΠΈΠΊΠ° Π² ΠΏΠΎΠ»Π·Π° Π½Π° ΡΡΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΠΈΡΠ΅ ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠ²Π½ΠΈ ΡΠ΅Ρ
Π½ΠΈΠΊΠΈ (ΡΡΡΠ°Π·Π²ΡΠΊΠΎΠ²Π°ΡΠ° ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΈ ΠΊΠΎΠ±Π»Π°ΡΠΎΡ-ΡΠ΅Ρ
Π½ΠΈΠΊΠ°ΡΠ°).-------------------------------------Β The purpose of the current article is to make a comparative clinical study of modern operating techniques and cold dissection tonsillectomy. During a period of two years in the ENT department at the Military Medical Academy - Sofia were performed 176 tonsillectomies in patiens between 10 and 45 years of age. 45% of the patients were operated using the conventional methods, 35% were operated using Ultracision and 20% were operated using the radiofrequency Coblation technology.The results showed considerable difference in favor of moden operating techniques (ultrasonic scalpel tonsillectomy or coblation tonsillectomy)
Serotonin Modulates Oscillations of the Membrane Potential in Isolated Spinal Neurons from Lampreys
Studies were performed on spinal neurons from lampreys isolated by an enzymatic/mechanical method using pronase. The effects of 100 Β΅M serotonin (5-HT) on membrane potential oscillations induced by a variety of excitatory amino acids were studied. 5-HT was found to depolarize branched cells (presumptive motoneurons and interneurons) by 2β6 mV without inducing membrane potential oscillations. However, when oscillations were already present because of an excitatory amino acid, 5-HT changed the parameters of these oscillations, increasing the amplitudes of all types of oscillations, increasing the frequency of irregular oscillations, and increasing the duration of the depolarization plateaus accompanied by action potentials. Serotonin modulation of the effects of excitatory amino acids and the electrical activity of cells in the neural locomotor network facilitates motor activity and leads to increases in the contraction of truncal muscles and more intense movements by the animal. The possible mechanisms of receptor coactivation are discussed, along with increases in action potential frequency and changes in the parameters of the locomotor rhythm
Nonlinear emission dynamics of a GaAs microcavity with embedded quantum wells
The emission dynamics of a GaAs microcavity at different angles of
observation with respect to the sample normal under conditions of nonresonant
picosecond-pulse excitation is measured. At sufficiently high excitation
densities, the decay time of the lower-polariton emission increases with the
polariton wavevector; at low excitation densities the decay time is independent
of the wavevector. The effect of additional nonresonant continuous illumination
on the emission originating from the bottom of the lower polariton branch is
investigated. The additional illumination leads to a substantial increase in
the emission intensity (considerably larger than the intensity of the
photoluminescence excited by this illumination alone). This fact is explained
in terms of acceleration of the polariton relaxation to the radiative states
due to scattering by charge carriers created by the additional illumination.
The results obtained show, that at large negative detunings between the photon
and exciton modes, polariton-polariton and polariton-free carrier scattering
are the main processes responsible for the filling of states near the bottom of
the lower polariton branch.Comment: 10 pages, 6 figures. This is an author-created, un-copyedited version
of an article accepted for publication in Journal of Physics: Condesed
Matter. IOP Publishing Ltd is not responsible for any errors or omissions in
this version of the manuscript or any version derived from i
The Effects of Serotonin on Functionally Diverse Isolated Lamprey Spinal Cord Neurons
The experiments reported here showed that application of serotonin (5-hydroxytryptamine, 5-HT) (100 Β΅ M) did not induce any significant current through the membranes of any of the spinal neurons studied (n = 62). At the same time, the membranes of most motoneurons and interneurons (15 of 18) underwent slight depolarization (2β6 mV) in the presence of 5-HT, which was not accompanied by any change in the input resistance of the cells. Depolarization to 10β20 mV occurred in some cells (3 of 18) of these functional groups, this being accompanied by 20β60% decreases in input resistance. The same concentration of 5-HT induced transient low-amplitude depolarization of most sensory spinal neurons (dorsal sensory cells), this changing smoothly to long-term hyperpolarization by 2β7 mV. The input resistance of the cell membranes in these cases showed no significant change (n = 8). Data were obtained which provided a better understanding of the mechanism by which 5-HT modulates the activity of spinal neurons. Thus, 5-HT facilitates chemoreceptive currents induced by application of NMDA to motoneurons and interneurons, while the NMDA responses of dorsal sensory cells were decreased by 5-HT. 5-HT affected the post-spike afterresponses of neurons. 5-HT significantly decreased the amplitude of afterhyperpolarization arising at the end of the descending phase of action potentials in motoneurons and interneurons and increased the amplitude of afterdepolarization in these types of cells. In sensory spinal neurons, 5-HT had no great effect on post-spike afterresponses. The results obtained here support the suggestion that 5-HT significantly modulates the activity of spinal neurons of different functional types. 5-HT facilitates excitation induced by subthreshold depolarization in motoneurons and some interneurons, facilitating the generation of rhythmic discharges by decreasing afterhyperpolarization. In sensory cells, 5-HT enhances inhibition due to hyperpolarization, suppressing NMDA currents. The differences in the effects of 5-HT on functionally diverse neurons are presumed to be associated with the combination of different types of 5-HT receptors on the membranes of these types of spinal neurons
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