Bound states of scalar particles in the presence of a short range potential

We analyze the behavior of the energy spectrum of the Klein-Gordon equation in the presence of a truncated hyperbolic tangent potential. From our analysis we obtain that, for some values of the potential there is embedding of the bound states into the negative energy continuum, showing that, in opposition to the general belief, relativistic scalar particles in one-dimensional short range potentials can exhibit resonant behavior and not only the Schiff-Snyder effect.Comment: To appear in Modern Physics Letters

Selection of "Selection" Sources from Harvesting Varieties According to Hills Conditions

The article describes the feasibility of selecting promising sources of selection of grassland forage species suitable for hills and their use in the phytomelioration of hill pastures

English → Russian MT evaluation campaign

This paper presents the settings and the result of the ROMIP 2013 MT shared task for the English→Russian language direction. The quality of generated translations was assessed using automatic metrics and human evaluation. We also discuss ways to reduce human evaluation efforts using pairwise sentence comparisons by human judges to simulate sort operations

Induced current in the presence of magnetic flux tube of small radius

The induced current density, corresponding to the massless Dirac equation in (2+1) dimensions in a magnetic flux tube of small radius is considered. This problem is important for graphene. In the case, when an electron can not penetrate the region of nonzero magnetic field, this current is the odd periodical function of the magnetic flux. If the region inside the magnetic tube is not forbidden for penetration of electron, the induced current is not a periodical function of the magnetic flux. However in the limit $R\to 0$, where $R$ is the radius of magnetic flux tube, this function has the universal form which is independent of the magnetic field distribution inside the magnetic tube at fixed value of the magnetic flux.Comment: 5 pages, 1 figur

Planar Dirac Electron in Coulomb and Magnetic Fields

The Dirac equation for an electron in two spatial dimensions in the Coulomb and homogeneous magnetic fields is discussed. For weak magnetic fields, the approximate energy values are obtained by semiclassical method. In the case with strong magnetic fields, we present the exact recursion relations that determine the coefficients of the series expansion of wave functions, the possible energies and the magnetic fields. It is found that analytic solutions are possible for a denumerably infinite set of magnetic field strengths. This system thus furnishes an example of the so-called quasi-exactly solvable models. A distinctive feature in the Dirac case is that, depending on the strength of the Coulomb field, not all total angular momentum quantum number allow exact solutions with wavefunctions in reasonable polynomial forms. Solutions in the nonrelativistic limit with both attractive and repulsive Coulomb fields are briefly discussed by means of the method of factorization.Comment: 18 pages, RevTex, no figure

Vortex Interferometric Microscopy with Laguerre-Gaussian Beams

In the present research, we discuss the results of analysis of coherent light beams carrying an optical vortex and propagating through the isotropic medium with a complex surface microrelief and its application to super resolution microscopy. It was shown, that phase analysis of singular beam with single charged centered optical vortex allow to retrieve information about sample surface relief. High spatial resolution caused by vortex helical phase sensitivity to disturbances in wave front after reflection or spreading through studying sample, which can be optically transparent or have a reflecting surface. This method applicable for non-destructive testing of live cells and biological tissues in real-time regime with exceeding optical diffraction limit. Vertical resolution of a microscope based on the phase singularity of Laguerre-Gaussian beams of low order can be achieved down to 5,27 nm for helium-neon laser source for optically transparent and reflecting surfaces. Keywords: optical vortex, phase, microscopy, singularit

The polarization tensor of neutral gluons in external fields at high temperature

The one-loop polarization operator of neutral gluons in the background constant Abelian isotopic, $H_{3}$, and hypercharge, $H_{8}$, chromomagnetic fields combined with $A_0$ electrostatic potential at high temperature is calculated. The case when $A_0=0$ is investigated separately. The proper time method is applied. It is found that neutral gluons do not acquire magnetic masses in the background fields, in contrast to the charged ones. The application of the results are discussed.Comment: 13 pages, 1 figur

Effects of pyrocatechol on neuromuscular transmission

Effects of pyrocatechol on neuromuscular transmission were studied both in the frog pectoral-cutaneous muscle and in the mouse phrenic-diaphragmatic preparation by means of extracellular microelectrode recording of synaptic signals. Pyrocatechol applied in a concentration of 0.05 mM increased the frequency of miniature end-plate currents (MEPC) and the amplitude of end-plate current (EPC) by increasing its quantum content. Pyrocatechol also increased the duration of presynaptic response. When voltage-dependent potassium channels had been blocked, pyrocatechol affected neither the EPC quantum content nor the duration of presynaptic response. It is suggested that the pyrocatechol-induced enhancement of transmitter release results from modulatory effects of pyrocatechol on voltage-dependent potassium current in the membrane of a nerve terminal. © 1995 Plenum Publishing Corporation

2-Anilino-3-(2-hy­droxy­prop­yl)-4-methyl-1,3-thia­zol-3-ium chloride

In the title compound, C13H17N2OS+·Cl−, the thia­zolium ring mean plane makes a dihedral angle of 55.46 (9)° with the benzene ring. In the propanol group, the N—C—C—C and N—C—C—O torsion angles are 172.58 (15) and 52.9 (2)°, respectively, and the S—C—C—C torsion angle is 178.99 (18)°. In the crystal, mol­ecules are linked by O—H⋯Cl and N—H⋯Cl hydrogen bonds, forming zigzag chains along [001]. There is also a C—H⋯Cl inter­action present