Electrically neutral Dirac particles in the presence of external fields: exact solutions

In the present article we present exact solutions of the Dirac equation for electric neutral particles with anomalous electric and magnetic moments. Using the algebraic method of separation of variables, the Dirac equation is separated in cartesian, cylindrical and spherical coordinates, and exact solutions are obtained in terms of special functions.Comment: 20pp, IVIC-CFLE-93/02 (this is a version without Tex problems, the first version was corrupted

Vacuum effects in an asymptotically uniformly accelerated frame with a constant magnetic field

In the present article we solve the Dirac-Pauli and Klein Gordon equations in an asymptotically uniformly accelerated frame when a constant magnetic field is present. We compute, via the Bogoliubov coefficients, the density of scalar and spin 1/2 particles created. We discuss the role played by the magnetic field and the thermal character of the spectrum.Comment: 17 pages. RevTe

Field induced evolution of regular and random 2D domain structures and shape of isolated domains in LiNbO₃ and LiTaO₃

The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging

Marangoni instability in oblate droplets suspended on a circular frame

We study theoretically internal flows in a small oblate droplet suspended on the circular frame. Marangoni convection arises due to a vertical temperature gradient across the drop and is driven by the surface tension variations at the free drop interface. Using the analytical basis for the solutions of Stokes equation in coordinates of oblate spheroid we have derived the linearly independent stationary solutions for Marangoni convection in terms of Stokes stream functions. The numerical simulations of the thermocapillary motion in the drops are used to study the onset of the stationary regime. Both analytical and numerical calculations predict the axially-symmetric circulatory convection motion in the drop, the dynamics of which is determined by the magnitude of the temperature gradient across the drop. The analytical solutions for the critical temperature distribution and velocity fields are obtained for the large temperature gradients across the oblate drop. These solutions reveal the lateral separation of the critical and stationary motions within the drops. The critical vortices are localized near the central part of a drop, while the intensive stationary flow is located closer to its butt end. A crossover to the limit of the plane film is studied within the formalism of the stream functions by reducing the droplet ellipticity ratio to zero value. The initial stationary regime for the strongly oblate drops becomes unstable relative to the many-vortex perturbations in analogy with the plane fluid films with free boundaries

Circulating Marangoni flows within droplets in smectic films

We present theoretical study and numerical simulation of Marangoni convection within ellipsoidal isotropic droplets embedded in free standing smectic films (FSSF). The thermocapillary flows are analyzed for both isotropic droplets spontaneously formed in FSSF overheated above the bulk smectic-isotropic transition, and oil lenses deposited on the surface of the smectic film. The realistic model, for which the upper drop interface is free from the smectic layers, while at the lower drop surface the smectic layering still persists is considered in detail. For isotropic droplets and oil lenses this leads effectively to a sticking of fluid motion at the border with a smectic shell. The above mentioned asymmetric configuration is realized experimentally when the temperature of the upper side of the film is higher than at the lower one. The full set of stationary solutions for Stokes stream functions describing the Marangoni convection flows within the ellipsoidal drops were derived analytically. The temperature distribution in the ellipsoidal drop and the surrounding air was determined in the frames of the perturbation theory. As a result the analytical solutions for the stationary thermocapillary convection were derived for different droplet ellipticity ratios and the heat conductivity of the liquid crystal and air. In parallel, the numerical hydrodynamic calculations of the thermocapillary motion in the drops were performed. Both the analytical and numerical simulations predict the axially-symmetric circulatory convection motion determined by the Marangoni effect at the droplet free surface. Due to a curvature of the drop interface a temperature gradient along its free surface always persists. Thus, the thermocapillary convection within the ellipsoidal droplets in overheated FSSF is possible for the arbitrarily small Marangoni numbers

The effects of innovative changes influence on social and economic processes of the region development

Development of strategy of social and economic development of the Voronezh region till 2035 requires the careful analysis of a condition of all activities of the region, their interaction and interference. The special role in this process belongs to the higher school as the engine of knowledge, information and innovations. In case of all conservatism of an education system its task not only to give estimates and forecasts of the future, but also to serve as a leader of changes in all industries. The models realizing these tasks are a possibility of receipt of the effective instrument of increase in innovation of potential of economy of the region, forming of the environment which is adequately reflecting scientific and technical and economic challenges of modern realities and also developments of processes and technologies of transition of economy of the region to the principles of digital economy. Direct task of the higher school are increase in the amount of knowledge which is saved up by society, handling and transformation of information to knowledge, generation of new information and new knowledge, forming of the competitive specialist. In article approaches to an impact assessment of changes in the higher school on processes of social and economic development of the region, to classification of straight lines and side effects (spillover-effects) in the conditions of development of programs of a strategic development of the region are considered, the model of development of the higher school taking into account spillover-effect based on the principles of digital economy is offered. For the purpose of an impact assessment of changes in the higher school on processes of social and economic development in the region the task is set to analyse influence of various factors at each other, and also on basic factors of economic growth of the region

Pyramidal amide nitrogen in N-acyloxy-N-alkoxyureas and N-acyloxy-N-alkoxycarbamates

The XRD studies of N-acyloxy-N-alkoxyamides 1, 2 have revealed a highly pyramidal configuration of amide nitrogen in the O–N–O group