Bosonic Spectral Function and The Electron-Phonon Interaction in HTSC Cuprates

In Part I we discuss accumulating experimental evidence related to the structure and origin of the bosonic spectral function in high-temperature superconducting (HTSC) cuprates at and near optimal doping. Some global properties of the spectral function, such as number and positions of peaks, are extracted by combining optics, neutron scattering, ARPES and tunnelling measurements. These methods give convincing evidence for strong electron-phonon interaction (EPI) with the coupling constant between 1-3 in cuprates near optimal doping. Here we clarify how these results are in favor of the Eliashberg-like theory for HTSC cuprates near optimal doping. In Part II we discuss some theoretical ingredients - such as strong EPI, strong correlations - which are necessary to explain the experimental results related to the mechanism of d-wave pairing in optimally doped cuprates. These comprise the Migdal-Eliashberg theory for EPI in strongly correlated systems which give rise to the forward scattering peak. The latter is further supported by the weakly screened Madelung interaction in the ionic-metallic structure of layered cuprates. In this approach EPI is responsible for the strength of pairing while the residual Coulomb interaction (by including spin fluctuations) triggers the d-wave pairing.Comment: 59 pages, 38 figures, review articl

On the theory of magnetic field dependence of heat conductivity in dielectric in isotropic model

Phonon polarization in a magnetic field is analyzed in isotropic model. It is shown, that at presence of spin-phonon interaction phonon possess circular polari-zation which causes the appearance of heat flux component perpendicular both to temperature gradient and magnetic field.Comment: 5 pages, 0 figure

Information Seek and Retrieval Mechanisms Based on Interactive Dynamics Linking Technology

The paper discusses the approach to dynamic hypertext technology used for query expansion and development. Two schemes of links creation on the fly are presented. The first one, System controlled scheme, generates (computes) hypertext links on retrieved documents output phase. In the second one, User controlled scheme, terms in viewed document are highlighted (and can be further used as a query in selected resource by one click) in accordance with user profile. The link creation mechanism is specified parametrically through the specification of the resource and selected (i.e. controlled) by the user. Linking mechanism is considered as a component of IR&S process, well controlled by user thought graphic interface.     Keywords: Information Retrieval Interface; Dynamic Linking; Hypertext Technology; System-Human Information Processing; Dynamic Query Reformulation

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

ETEKOS experimental ecological system

The problem of changes in the ecology resulting, for example, in increases in water temperature because of discharges from large thermal power plants is considered. An experiment creating a model of such an ecological system is described