Correlation-induced localization

A new paradigm of Anderson localization caused by correlations in the long-range hopping along with uncorrelated on-site disorder is considered which requires a more precise formulation of the basic localization-delocalization principles. A new class of random Hamiltonians with translation-invariant hopping integrals is suggested and the localization properties of such models are established both in the coordinate and in the momentum spaces alongside with the corresponding level statistics. Duality of translation-invariant models in the momentum and coordinate space is uncovered and exploited to find a full localization-delocalization phase diagram for such models. The crucial role of the spectral properties of hopping matrix is established and a new matrix inversion trick is suggested to generate a one-parameter family of equivalent localization/delocalization problems. Optimization over the free parameter in such a transformation together with the localization/delocalization principles allows to establish exact bounds for the localized and ergodic states in long-range hopping models. When applied to the random matrix models with deterministic power-law hopping this transformation allows to confirm localization of states at all values of the exponent in power-law hopping and to prove analytically the symmetry of the exponent in the power-law localized wave functions.Comment: 14 pages, 8 figures + 5 pages, 2 figures in appendice

Statistics of Green's functions on a disordered Cayley tree and the validity of forward scattering approximation

The accuracy of the forward scattering approximation for two-point Green's functions of the Anderson localization model on the Cayley tree is studied. A relationship between the moments of the Green's function and the largest eigenvalue of the linearized transfer-matrix equation is proved in the framework of the supersymmetric functional-integral method. The new large-disorder approximation for this eigenvalue is derived and its accuracy is established. Using this approximation the probability distribution of the two-point Green's function is found and compared with that in the forward scattering approximation (FSA). It is shown that FSA overestimates the role of resonances and thus the probability for the Green's function to be significantly larger than its typical value. The error of FSA increases with increasing the distance between points in a two-point Green's function

MODELING THE MANIFESTATIONS OF THE HUMAN FACTOR OF THE MARITIME CREW

Purpose. The article investigates the trajectories of the watch team members in maritime transport that lead to a decrease in the level of security. A formal apparatus is proposed, as well as software and hardware to identify the location of members of the watch team during the execution of complex maneuvers. Methodology. In the course of constructing the mathematical model, the most common schemes of interaction of watch members at the time of performing complex maneuvers were considered. The general problem was considered as a series of watchkeeping interactions that solve micro-tasks of ship control at a certain moment. As a result of simulation it is determined that a key role is played by the first mate, who is the most likely to deviate from the instructions, because of excessive activity or passivity in actions. Also, interaction models of members of the watchkeeping service within the framework of a multi-day ship passage are considered. Findings. Research shows that the formation of established interactions depends on the level of experience and qualifications of the members of the watchkeeping service. Overly active relocation of the mate, as well as function duplication of individual members of the watchkeeping service adversely affects the safety level in ship management. Software and hardware tools are proposed that allow identifying the location and movements of the watch team members, indicating deviations from the watchkeeping instructions for maritime transport. Originality. The authors for the first time developed software and hardware for analyzing the movements of the watchkeeping service members, allowing identifying violations of official instructions. Practical value. Based on the developed software and hardware identification of positions and movements of the members of the watchkeeping service, it becomes possible to more effectively manage the process of training navigators during simulator practice on the basis of the navigation simulator NTPRO 5000 at the Kherson State Maritime Academy, Ukraine. These studies can also be useful in studying the discipline «Organization of the crew actions in extreme conditions»

MAGNETIC PROPERTIES OF THIN FILMS OF IRON-YTTRIUM GARNET

Y3Fe5O12 thin films with nanometer thickness were obtained by pulsed laser deposition and their magnetic properties were studied. Evolution of magnetic properties with thickness was analyzed

FERROMAGNETIC RESONANCE IN THIN FILMS OF Y3FE5O12

Y3Fe5O12 thin films with nanometer thickness were obtained by pulsed laser deposition and their magnetic properties were studied. Evolution of magnetic properties with thickness was analyzed

Fast optical variability of SS 433

We study the optical variability of the peculiar Galactic source SS 433 using the observations made with the Russian Turkish 1.5-m telescope (RTT150). A simple technique which allows to obtain high-quality photometric measurements with 0.3-1 s time resolution using ordinary CCD is described in detail. Using the test observations of nonvariable stars, we show that the atmospheric turbulence introduces no significant distortions into the measured light curves. Therefore, the data obtained in this way are well suited for studying the aperiodic variability of various objects. The large amount of SS 433 optical light curve measurements obtained in this way allowed us to obtain the power spectra of its flux variability with a record sensitivity up to frequencies of ~0.5 Hz and to detect its break at frequency =~2.4e-3 Hz. We suggest that this break in the power spectrum results from the smoothing of the optical flux variability due to a finite size of the emitting region. Based on our measurement of the break frequency in the power spectrum, we estimated the size of the accretion-disk photosphere as 2e12 cm. We show that the amplitude of the variability in SS 433 decreases sharply during accretion-disk eclipses, but it does not disappear completely. This suggests that the size of the variable optical emission source is comparable to that of the normal star whose size is therefore R_O \approx 2e12 cm \approx 30 R_sun. The decrease in flux variability amplitude during eclipses suggests the presence of a nonvariable optical emission component with a magnitude m_R=~13.2.Comment: 12 pages, 11 figures. Accepted for publication in Astronomy Letters. The original version in Russian is available at http://hea.iki.rssi.ru/rtt150/ru/ss433_pazh10/pss433_fast.pd

Phenotypic and Molecular-Genetic Peculiarities of Yersinia pestis Strains from Trans-Baikal Steppe Plague Focus

The paper contains the data on the complex phenotypic and genotypic characteristics of Yersinia pestisstrains isolated in Trans-Baikal steppe plague focus before and after the succession of the main carrier which took place in the 1960s. Based on the PCR-analysis and multilocus sequence typing of glpD, melB, napA, rhaA, and iclR genes, encoding differentially significant properties such as glycerin, melibiose, rhamnose fermentation, isocitrate lyase production, and denitrification activity, developed are the proofs of affiliation of the studied strains to the biovariant antiqua of the plague agent main subspecies. Multilocus VNTR-analysis by seven locuses of variable tandem repeats – ms01, ms04, ms06, ms07, ms46, ms62 – has been used to establish genetic relations between the strains. Thus on the basis of the results obtained, it is established that the strains of the plague agent, isolated in the Trans-Baikal steppe focus in various periods of its existence, form one common branch on the phylogenetic tree of Y. pestis evolution

Анализ эффективности методов полиномиальной степени сложности при декомпозиции OLAP-кубов многомерных данных

The article investigates the problems of reduction (decomposition) of multidimensional data models in terms of hypercube OLAP-structures. Describes the case when a data structure is defined by the array that slices and dices the hypercube into the odd number of subcubes, and this set of subcube structures becomes decomposed. Defines an exact upper bound for increasing a computational performance of methods to analyze OLAP-data on subcubes, which determines the decomposition approach efficiency in comparison with the OLAP-data analysis on a complete unreduced hypercube. A compared efficiency of the hypercube decomposition into two subcubes on the sets consisting of the even and odd number of subcube structures has shown that with considerable data partitioning for methods of a polynomial complexity degree the decomposition efficiency essentially is independent on this factor and rises with increasing complexity degree of methods applied.When using the mathematical methods to study decomposition (reduction) of large hyper-cubes of multidimensional data of analytical OLAP systems into subcube components, there is a need to find conditions for minimising the computational complexity of methods to solve the problems of the OLAP hyper-cube analysis during data decomposition in comparison with using these methods for analyzing large amounts of information that is accumulated directly in the hyper-cubes of multidimensional OLAP-data to establish the criteria for decreasing or increasing computational performance when applying methods on the subcube components (reduction methods) as compared to applying these methods on a hypercube (non-reduction or traditional methods), depending on one or another degree of complexity of complex methods.The article provides an accurate quantitative estimate of decreasing computational complexity of reduction methods for analyzing OLAP-cubes as compared to the non-reduction methods in the case when said methods have the polynomial complexity and the original hypercube array of data comprises the odd number of subcubes.В работе исследуются проблемы редукции (декомпозиции) моделей многомерных данных в виде гиперкубовых OLAP-структур. Рассматривается случай, когда структура данных определяется решеткой, разбивающей гиперкуб на нечетное количество подкубов, и декомпозиция гиперкуба осуществляется на этом множестве подкубовых структур. Установлена точная верхняя граница увеличения вычислительной производительности методов анализа OLAP-данных на подкубах, определяющая эффективность декомпозиционного подхода по сравнению с анализом OLAP-данных на полном нередуцированном гиперкубе. Проведено сравнение эффективности декомпозиции гиперкуба на два подкуба на множествах, состоящих из четного и нечетного числа подкубовых структур и показано, что при большом дроблении данных для методов полиномиальной степени сложности эффективность декомпозиции практически не зависит от этого фактора и растет с ростом степени сложности применяемых методов.При исследовании математическими методами декомпозиции (редукции) больших гиперкубов многомерных данных аналитических OLAP-систем на подкубовые компоненты ищутся условия уменьшения вычислительной сложности методов решения задач анализа OLAP-гиперкубов при декомпозиции данных по сравнению с применением этих методов к анализу больших массивов информации, накапливаемых непосредственно в гиперкубах многомерных OLAP-данных для установления критериев уменьшения или увеличения вычислительной производительности при применении методов на подкубовых компонентах (редукционные методы) по сравнению с применением этих методов на гиперкубе (нередукционные или традиционные методы) в зависимости от классов той или иной степеней сложности рассматриваемых методов.В статье получена точная количественная оценка уменьшения вычислительной сложности редукционных методов анализа OLAP-кубов по сравнению с нередукционными методами в ситуации, когда данные методы имеют полиномиальную степень сложности, а решетка исходного гиперкуба данных состоит из нечетного числа подкубов