Ab initio calculations of the physical properties of transition metal carbides and nitrides and possible routes to high-Tc

Ab initio linear-response calculations are reported of the phonon spectra and the electron-phonon interaction for several transition metal carbides and nitrides in a NaCl-type structure. For NbC, the kinetic, optical, and superconducting properties are calculated in detail at various pressures and the normal-pressure results are found to well agree with the experiment. Factors accounting for the relatively low critical temperatures Tc in transition metal compounds with light elements are considered and the possible ways of increasing Tc are discussed.Comment: 19 pages, 7 figure

HISTORY AND RESULTS OF THE INTRODUCTION OF PALMS (ARECACEAE C.H. SCHULTZ) ON THE SOUTHERN COAST OF THE CRIMEA

The results of the introduction of palms have been summarized, and the assortment, opportunities and conditions of their cultivation on  the Southern Coast of the Crimea (SCC) defined. Long-term  observations on the experimental plants with an assessment of their  prospects according to a frosting scale during severe winters and  biometric measurements of their habit by instrumental methods  have been conducted. The article describes the history and results of the palms' introduction beginning from 1814 up to the present  moment. It was established that growth and development of palms  in the NBG's arboretum depend not only on their winter resistance  but also on the growing conditions and cultivation practices. The  results of the palms' introduction over a 30-year span of the  research (1984-2014) through the example of their growth and  development in the NBG's arboretum have been summed up. The  data about the characteristic habits and reproductive capabilities for  the year 1984 have been provided and compared with the same  parameters obtained in 2014 on the same experimental trees. A  picture of actual damages of various palm species during severe  winters has been shown, and the degree of their tolerance to  extreme negative temperatures determined. A promising assortment of palms tested in the NBG's arboretum has been identified, and the  conditions of their cultivation on the SCC shown. The environmental  and biological criteria influencing growth and development of 12  species of palms have been defined. Recommendations as to  agricultural practices, protection in winter, and rational utilization of palms in ornamental gardening have been provided

Vortex-antivortex wavefunction of a degenerate quantum gas

A mechanism of a pinning of the quantized matter wave vortices by optical vortices in a specially arranged optical dipole traps is discussed. The vortex-antivortex optical arrays of rectangular symmetry are shown to transfer angular orbital momentum and form the "antiferromagnet"-like matter waves. The separable Hamiltonian for matter waves in pancake trapping geometry is proposed and 3D-wavefunction is factorized in a product of wavefunctions of the 1D harmonic oscillator and 2D vortex-antivortex quantum state. The 2D wavefunction's phase gradient field associated via Madelung transform with the field of classical velocities forms labyrinth-like structure. The macroscopic quantum state composed of periodically spaced counter-rotating BEC superfluid vortices has zero angular momentum and nonzero rotational energy.Comment: 11 pages, 5 figure