arXiv subjects
Publications and source records attributed to M. N. Shneider.
It is shown that the polarization forces in a weakly ionized plasma lead to a substantial increase in the fluxes of neutral atoms and molecules to the surface of charged nanoparticles. Thus, the nanoparticles can change thermal balance due to the acceleration of atoms and molecules in the dipole potential and subsequent inelastic collisions to the nanoparticles.
It is shown the principal possibility of bypassing damaged demyelinated portions of the nervous tissue, thereby restoring its normal function for the passage of action potentials.
A new mechanism for inducing convection during IR laser interaction with water or any absorbing liquid is described theoretically. The numerical simulations performed using the developed model show that the optical pressure and ponderomotive forces produces water flow in the direction of the laser beam propagation. In the later stage of interaction, when water temperature rises, the Archimedes force becomes first comparable and then dominant producing convection directed against the vector of gravitational acceleration (upward). The theoretical estimates and the numerical simulations predict fluid dynamics that is similar to the observed in the previous experiments.
A theory is developed for the initial stage of cavitation in the framework of Zel'dovich-Fisher theory of nucleation in the field of negative pressure, while taking into account the surface tension dependence on the nanopore radius. A saturation mechanism is proposed that limits the exponential dependence of the nucleation rate on the energy required to create nanopores. An estimate of the saturated density of nanopores at the nucleation stage is obtained. It is shown that Rayleigh scattering can detect nanopores arising at the initial stage of cavitation development.
It is shown that the scattering of laser radiation on cavitation ruptures in fluids is similar to the scattering by gas particles. When the characteristic dimensions of microscopic voids and bubbles are considerably smaller than the laser wavelength, the scattered light is in the Rayleigh regime and allows detecting cavitation in the very early stages of its inception. The simple estimates of the scattered radiation intensity and the dynamics of its changes in connection with the generation of cavitation in the test volume are obtained, allowing us to find the critical conditions for the cavitation inception.
Multiple observations of Blue Jets (BJ)) show that BJ emits a fan of streamers similar to a laboratory leader. Moreover,in the exponential atmosphere those long streamers grow preferentially upward, producing a narrow coneconfined by the aperture angle. It was also noticed that BJ are similar to the streamer zone of a leader (streamer corona) and the modeling studies based on the streamers fractal structure were conducted. Objective of this paper is to study the fractal dimension of the bunch of streamer channels emitted by BJ, at different altitude and under the varying reduced electric field. This similarity analysis has been done in three steps: First we described the dendritic structure of streamers in corona discharge applying the fractal theory. Then using this model and the data from existing laboratory experiments we obtained the fractal dimension of the branching streamer channels. Finally the model was validated by the observations of BJ available from the literature.
The paper considers an effect of intensive ultrasound on the suspension of soot microparticles and nanoparticles in the inert gas, resulting in the coagulation of relatively large soot particles and leading to the improvement of the efficiency of production of nanoparticles, as has been observed in experiments. The effect of the particles charge on the possibility of coagulation is analyzed.
A possible mechanism for the synchronization of action potential propagation along a bundle of neurons (ephaptic coupling) is considered. It is shown that this mechanism is similar to the salutatory conduction of the action potential between the nodes of Ranvier in myelinated axons. The proposed model allows us to estimate the scale of the correlation, i.e., the distance between neurons in the nervous tissue, wherein their synchronization becomes possible. The possibility for experimental verification of the proposed model of synchronization is discussed.
This paper discusses the nanopores emerging and developing in a liquid dielectric under the action of the ponderomotive electrostrictive forces in a nonuniform electric field. It is shown that the gradient of the electric field in the vicinity of the rupture (cavitation nanopore) substantially increases and determines whether the rupture grows or collapses. The cavitation rupture in the liquid (nanopore) tends to stretch along the lines of the original field. The mechanism of the breakdown associated with the generation of secondary ruptures in the vicinity of the poles of the nanopore is proposed. The estimations of the extension time for nanopore in water and oil (polar and nonpolar liquids, respectively) are presented. A new mechanism of nano- and subnanosecond breakdown in the insulating (transformer) oil that can be realized in the vicinity of water microdroplets in modern nanosecond high-voltage devices is considered
In this paper the problem of surface charge of the lipid membrane immersed in the physiological solution is considered. It is shown that both side of the bilayer phospholipid membrane surface are negatively charged. A self-consistent model of the potential in solution is developed, and a stationary charge density on the membrane surface is found. It is shown that the ions of the surface charge are in a relatively deep (as compared to kBT) potential wells, which are localized near the dipole heads of phospholipid membrane. It makes impossible for ions to slip along the membrane surface. Simple experiments for verifying the correctness of the considered model are proposed. A developed approach can be used for estimations of the surface charges on the outer and inner membrane of the cell.
This paper presents a short selective review of the non-thermal weak microwave field impact on a nerve fiber. The published results of recent experiments are reviewed and analyzed. The theory of the authors is presented, according to which there are strongly pronounced resonances in the range of about 30-300 GHz associated with the excitation of ultrasonic vibrations in the membrane as a result of interactions with the microwave radiation. These forced vibrations create acoustic pressure, which may lead to the redistribution of the protein transmembrane channels, thus changing the threshold of the action potential excitation in the axons of the neural network. The problem of surface charge on the bilayer lipid membrane of the nerve fiber is discussed. Various experiments for observing the effects considered are also discussed.
It is demonstrated that current theoretical models utilize equations for description of laser beam propagation in nonlinear media that were deduced under the assumption of homogeneity of dielectric constant of the media and for the case of planar wave front. Here, we deduce complete wave propagation equation that includes inhomogeneity of the dielectric constant and present this propagation equation in compact vector form. Although similar equations are known in the narrow fields, such as, radio wave propagation in ionosphere and electro-magnetic and acoustic wave propagation in stratified media, we develop here a novel approach of using such equations in modeling of laser beam propagation in nonlinear media. The inadequacy of the assumptions under which the propagation equations are derived in the current model is demonstrated. Also, mathematical derivation is presented that describes foundation and validates our previously reported method for modeling of laser beam propagation in nonlinear media by blending solution of linear Helmholtz equation with a correction term representing nonlinear field perturbation expressed in terms of paraxial ray-optics (eikonal) equation. Unlike all previous theoretical approaches developed during past five decades, our approach satisfies correspondence principle since in the limit of zero-length wavelength it reduces from physical to geometrical optics.
In this paper, we analyze the effect of the redistribution of the transmembrane ion channels in the axon caused by longitudinal acoustic vibrations of the membrane. These oscillations can be excited by an external source of ultrasound and weak microwave radiation interacting with the charges sitting on the surface of the lipid membrane. It is shown, using the Hodgkin-Huxley model of the axon, that the density redistribution of transmembrane sodium channels may reduce the threshold of the action potential, up to its spontaneous initiation. At the significant redistribution of sodium channels in membrane, the rarefaction zones of the transmembrane channels density are formed, blocking the propagation of the action potential. Blocking the action potential propagation along the axon is shown to cause anestesia in the example case of a squid axon. Various approaches to experimental observation of the effects considered in this paper are discussed.
We study the dynamic contraction a self-sustained glow discharge in air in a rectangular duct with convective cooling. A two dimensional numerical model of the plasma contraction was developed in a cylindrical frame. The process is described by a set of time-dependent continuity equations for the electrons, positive and negative ions; gas and vibrational temperature; and equations which account for the convective heat and plasma losses by the transverse flux. Transition from the uniform to contracted state was analyzed. It was shown that such transition experiences a hysteresis, and that the critical current of the transition increases when the gas density drops. Possible coexistence of the contracted and uniform state of the plasma in the discharge, where the current flows along the density gradient of the background gas, is discussed.
This paper proposes a method for studying the early stages of the cavitation development in arbitrary, non-stationary conditions. This method is based on the comparison of the results of calculations in the framework of a theoretical model of the liquid dielectrics motion in a strong non-uniform electric field and experiments with controlled parameters. This approach allows us to find the critical negative pressure, at which cavitation begins to develop, and to determine the values of the constants in the classical models of cavitation.
We use a conceptually new approach to theoretical modeling of self-focusing in which we integrated diffractive and geometrical optics in order to explain and predict emission of white light and colored rings observed in ultrashort laser pulse interaction. In our approach laser beam propagation is described by blending solution of linear Maxwell's equation and a correction term that represents nonlinear field perturbation expressed in terms of paraxial ray-optics (eikonal) equation. No attempt is made to create appearance of exhaustive treatment via use of complex mathematical models. Rather, emphasis is placed on elegance of the formulations leading to fundamental understanding of underlying physics and, eventually, to an accurate practical numerical model capable of simulating white light generation and conical emission of colored rings produced around the filament.
We propose a non-thermal mechanism of weak microwave field impact on a nerve fiber. It is shown that in the range of about 30 - 300 GHz there are strongly pronounced resonances associated with the excitation of ultrasonic vibrations in the membrane as a result of interaction with electromagnetic radiation. These vibrations create acoustic pressure which may lead to the redistribution of the protein transmembrane channels, and, thus, changing the threshold of the action potential excitation in the axons of the neural network. The influence of the electromagnetic microwave radiation on various specific areas of myelin nerve fibers was analyzed: the nodes of Ranvier, and the so-called initial segment - the area between the neuron hillock and the first part of the axon covered with the myelin layer. It is shown that the initial segment is the most sensitive area of the myelined nerve fibers from which the action potential normally starts.
A theoretical study of power loss from periphery of an ultrashort pulse laser beam and temporally resolved defocussing produced by laser induced plasma are performed using paraxial approximation. Our analysis incorporate consideration of spatial distribution of the laser beam irradiance and the results show that substantial power losses (10%-80%) occur from the beam periphery limiting length of a filament. It was also shown that generally accepted concept of self-focusing critical power is inconsistent with consideration of self-induced refraction of spatially distributed laser beam. A new criterion for self-focusing and hypothesis for multiple filamentation are proposed.