Scattering theory with finite-gap backgrounds: Transformation operators and characteristic properties of scattering data

We develop direct and inverse scattering theory for Jacobi operators (doubly infinite second order difference operators) with steplike coefficients which are asymptotically close to different finite-gap quasi-periodic coefficients on different sides. We give necessary and sufficient conditions for the scattering data in the case of perturbations with finite second (or higher) moment.Comment: 23 page

Exact quantum master equation for a molecular aggregate coupled to a harmonic bath

We consider a molecular aggregate consisting of $N$ identical monomers. Each monomer comprises two electronic levels and a single harmonic mode. The monomers interact with each other via dipole-dipole forces. The monomer vibrational modes are bilinearly coupled to a bath of harmonic oscillators. This is a prototypical model for the description of coherent exciton transport, from quantum dots to photosynthetic antennae. We derive an exact quantum master equation for such systems. Computationally, the master equation may be useful for the testing of various approximations employed in theories of quantum transport. Physically, it offers a plausible explanation of the origins of long-lived coherent optical responses of molecular aggregates in dissipative environments

Improving the efficiency of university management : teacher’s performance monitoring as a tool to promote the quality of education

This study aims to examine the essence of education monitoring, its place in the higher education management system and the practical implementation of teacher’s performance monitoring as a tool to promote the quality of education. The article considers theoretical aspects of monitoring as a tool to promote the quality of education, assesses the performance of the university departments, research and teaching staff and discusses the results and suggestions on how to improve monitoring activities in higher education. Based on their research and findings, the authors claimed that the monitoring of the performance of the university research and teaching staff on the base of an indicator system in terms of education, methodology, research, organization and counselling services would lead to valid conclusions as to the effective performance of both individual researchers and teachers and university departments, in general.peer-reviewe

Effect of Fe content on atomic and electronic structure of complex oxides Sr Ti,Fe O3 delta

Two series of SrTi1 xFexO3 amp; 948; STFO powders with different Fe content produced by two different methods, solid state reaction or modified Pechini synthesis, have been investigated by soft X ray absorption spectroscopy. The O1s K , Fe2p L2,3 and Ti2p L2,3 absorption spectra of STFO powders were analyzed. Partial substitution of Ti by Fe atoms in SrTiO3 were found to cause asymmetric distortion of TiO6 octahedrons which may violate the cubic symmetry of STFO. It was established that the distortion of TiO6 octahedrons increases with increasing Fe content. The joint analysis of the STFO spectra along with the reference compounds points to the presence mainly of Fe3 states in octahedral environment at small concentration of Fe atoms along with essentially smaller content of Fe4 states in octahedral environment where the latter contribution increases with increasing Fe content. Also a presence of Fe3 states in tetrahedral environment with Fe content higher than 50 is traced. A certain amount of Fe2 ions in an octahedral environment was also found in the STFO compound prepared by spray pyrolysis with Fe content higher than 75 . The O1s K absorption spectra point to increase in oxygen vacancy concentration with increasing Fe content. The lowest degree of structure distortions was traced in STFO35. Hence, the STFO35 compound seems to be mostly appropriate for technical application

The passport database of VIR’s bean collection as a tool for systemizing bean genetic diversity, studying the collection’s history, and monitoring the crop’s worldwide breeding (an overview)

The main document attesting the composition of a collection is the passport database (DB), which contains basic information about every accession: its name, status, origin, the year of its placement into the collection, etc. The effort to include every detail of such information into the database opens up a number of possibilities for structuring and exploring the diversity available. For the bean collection, the history of its systemization has had several stages. In 1923, systemic recording of bean accessions that entered the collection started with their registration in special journals, called catalogues. Since the middle of the 1960s, computer aids have been used for data logging and processing. In the 1990s, the DBs thus developed were transferred to personal computers. Today, such data are formatted as a computerized passport database, unified in accordance with modern international standards and consisting of 35 fields. Analysis of the Phaseolus passport database has shown that the bean collection consists of 6586 accessions, registered in the permanent catalogue. These accessions represent four cultivated species of different breeding status from 102 countries of the world. The largest percentage in the collection belongs to the accessions of European origin (61%). The accessions from North and South Americas (over 600 and 460 entries, respectively) make up 17% of the collection, while the gene pool of Asian countries, 16%. The biggest replenishments of VIR’s bean collection in its entire long history happened in the times of the USSR (2129 entries). The passport DB also makes it possible to conduct worldwide monitoring of the breeding work with beans, because it provides a comprehensive overview of the history of bean breeding and its present-day status in foreign countries, the ex-USSR republics and the Russian Federation. The purpose of this article has been to analyze the passport database of VIR’s bean collection and the information stored in it, and produce a retrospective essay on the documentation of the Phaseolus germplasm holdings at VIR

Spatial beam self-cleaning and supercontinuum generation with Yb-doped multimode graded-index fiber taper based on accelerating self-imaging and dissipative landscape

We experimentally demonstrate spatial beam self-cleaning and supercontinuum generation in a tapered Ytterbium-doped multimode optical fiber with parabolic core refractive index profile when 1064 nm pulsed beams propagate from wider (122 µm) into smaller (37 µm) diameter. In the passive mode, increasing the input beam peak power above 20 kW leads to a bell-shaped output beam profile. In the active configuration, gain from the pump laser diode permits to combine beam self-cleaning with supercontinuum generation between 520-2600 nm. By taper cut-back, we observed that the dissipative landscape, i.e., a non-monotonic variation of the average beam power along the MMF, leads to modal transitions of self-cleaned beams along the taper length

Dependence of the Energy Spectrum of UHE Cosmic Rays on the Latitude of an Extensive Air Shower Array

Several energy spectra of cosmic rays with energies E_0 \geq 10^17 eV measured at the Yakutsk EAS, AGASA, Haverah Park, HiRes, Auger, and SUGAR arrays are considered. It is shown that the fairly good mutual agreement of the spectrum shapes can be achieved if the energy of each spectrum is multiplied by a factor K specific for each spectrum. These factors exhibit a pronounced dependence on the latitude of the above-mentioned arrays.Comment: 4 pages, 4 figure

Cosmic Rays: The Second Knee and Beyond

We conduct a review of experimental results on Ultra-High Energy Cosmic Rays (UHECR's) including measurements of the features of the spectrum, the composition of the primary particle flux and the search for anisotropy in event arrival direction. We find that while there is a general consensus on the features in the spectrum -- the Second Knee, the Ankle, and (to a lesser extent) the GZK Cutoff -- there is little consensus on the composition of the primaries that accompany these features. This lack of consensus on the composition makes interpretation of the agreed upon features problematic. There is also little direct evidence about potential sources of UHECRs, as early reports of arrival direction anisotropies have not been confirmed in independent measurements.Comment: 46 pages, 30 figures. Topical Review to appear in J. Physics