Three-body treatment of the penetration through the Coulomb field of a two-fragment nucleus

On the basis of the Faddeev integral equations method and the Watson- Feshbach concept of the effective (optical) interaction potential, the first fully consistent three-body approach to the description of the penetration of a charged particle through the Coulomb field of a two-particle bound complex (composed of one charged and one neutral particles) has been developed. A general formalism has been elaborated and on its basis, to a first approximation in the Sommerfeld parameter, the influence of the nuclear structure on the probability of the penetration of a charged particle (the muon, the pion, the kaon and the proton) through the Gamow barrier of a two-fragment nucleus (the deuteron and the two lightest lambda hypernuclei, lambda hypertriton and lambda hyperhelium-5, has been calculated and studied.Comment: LaTeX, 30 pages, 4 eps figure

Empirical evaluation of accuracy of mathematical software used for availability assessment of fault-tolerant computer systems

Dependability assessment is typically based on complex probabilistic models. Markov and semi-Markov models are widely used to model dependability of complex hardware/software architectures. Solving such models, especially when they are stiff, is not trivial and is usually done using sophisticated mathematical software packages. We report a practical experience of comparing the accuracy of solutions stiff Markov models obtained using well known commercial and research software packages. The study is conducted on a contrived but realistic cases study of computer system with hardware redundancy and diverse software under the assumptions that the rate of failure of software may vary over time, a realistic assumption. We observe that the disagreement between the solutions obtained with the different packages may be very significant. We discuss these findings and directions for future research

КАТЕГОРІЯ СПРАВЕДЛИВОСТІ У СОЦІАЛЬНО-ФІЛОСОФСЬКИХ ІНТЕРПРЕТАЦІЯХ СУЧАСНОЇ СИСТЕМИ МІЖНАРОДНИХ ВІДНОСИН

The phenomenon of "fairness" as the fundamental category in contemporary philosophy, ethics, axiology, philosophy of politics, political ethics, philosophy of law, is conceptualized on the basis of cultural, politico-cultural, linguistic, comparative approaches. Its social philosophical deconstruction in the paradigm of the classical model of international relations is carried out. It is shown that this model provides for the formulation of equitable approaches to enable all the representatives of the international community is equivalent positions to build their own lives, taking into account the cultural traditions, mentality, nuances of national economy and education.Феномен справедливості, являючись фундаментальною категорією в сучасній філософії, етиці, аксіології, філософії політики, політичній етиці, філософії права, концептуалізується на основі підходів – соціокультурного, політико-культурного, лінгвістичного, компаративного, Здійснюється його соціально-філософська деконструкція в парадигмі класичної моделі міжнародних відносин. Показано, що саме така модель передбачає вироблення справедливих підходів, що дозволять усім представникам міжнародного співтовариства рівноцінно вибудовувати власне життя, враховуючи культурні традиції, особливості менталітету, нюанси національної економіки та освіти

Principles of microRNA regulation of a human cellular signaling network

MicroRNAs (miRNAs) are endogenous 22-nucleotide RNAs, which suppress gene expression by selectively binding to the 3-noncoding region of specific message RNAs through base-pairing. Given the diversity and abundance of miRNA targets, miRNAs appear to functionally interact with various components of many cellular networks. By analyzing the interactions between miRNAs and a human cellular signaling network, we found that miRNAs predominantly target positive regulatory motifs, highly connected scaffolds and most downstream network components such as signaling transcription factors, but less frequently target negative regulatory motifs, common components of basic cellular machines and most upstream network components such as ligands. In addition, when an adaptor has potential to recruit more downstream components, these components are more frequently targeted by miRNAs. This work uncovers the principles of miRNA regulation of signal transduction networks and implies a potential function of miRNAs for facilitating robust transitions of cellular response to extracellular signals and maintaining cellular homeostasis

Shape parameters of Galactic open clusters

(abridged) In this paper we derive observed and modelled shape parameters (apparent ellipticity and orientation of the ellipse) of 650 Galactic open clusters identified in the ASCC-2.5 catalogue. We provide the observed shape parameters of Galactic open clusters, computed with the help of a multi-component analysis. For the vast majority of clusters these parameters are determined for the first time. High resolution ("star by star") N-body simulations are carried out with the specially developed $\phi$GRAPE code providing models of clusters of different initial masses, Galactocentric distances and rotation velocities. The comparison of models and observations of about 150 clusters reveals ellipticities of observed clusters which are too low (0.2 vs. 0.3), and offers the basis to find the main reason for this discrepancy. The models predict that after $\approx 50$ Myr clusters reach an oblate shape with an axes ratio of $1.65:1.35:1$, and with the major axis tilted by an angle of $q_{XY} \approx 30^\circ$ with respect to the Galactocentric radius due to differential rotation of the Galaxy. Unbiased estimates of cluster shape parameters require reliable membership determination in large cluster areas up to 2-3 tidal radii where the density of cluster stars is considerably lower than the background. Although dynamically bound stars outside the tidal radius contribute insignificantly to the cluster mass, their distribution is essential for a correct determination of cluster shape parameters. In contrast, a restricted mass range of cluster stars does not play such a dramatic role, though deep surveys allow to identify more cluster members and, therefore, to increase the accuracy of the observed shape parameters.Comment: 13 pages, 12 figures, accepted for publication in Astronomy and Astrophysic

Підвищення якості контуру «літак–система автоматичного керування»

This article deals with model based approach to mathematical modeling process of an aircraftflight control system. Analysis of emergency situations depend on phases of flight is done. Application ofmodern model based technologies for automatic flight control systems development is considered. Theprogram for aircraft-automatic flight control system control loop simulation and visualization is developed.Improvement of the automatic flight control system characteristics is showed. Availability of practicalapplication of developed program in aerospace scope is considered. Use of the mentioned approachallows to facilitate automatic flight control system development, analyze and certification processПредставлен модельно-ориентированный подход к процессу математического моделирования законов системы автоматического управления. Выполнен анализ аварийных ситуаций в зависимости от этапа полета. Рассмотрено применение современной модельно ориентированной технологии разработки законов системы автоматического управления. Разработана программа моделирования и визуализации контура самолет-система автоматического управления. Показано улучшение точности выдерживания параметров системы автоматическогоуправления. Рассмотрена возможность практического применения разработанной программы в авиационнойотрасли. Использование указанного подхода позволит сократить время на разработку, анализ и сертификациюсистемы автоматического управленияПредставлено модельно-орієнтований підхід до процесу математичного моделювання законів системи автоматичного керування. Виконано аналіз аварійних ситуацій в залежності від етапу польоту. Розглянуто використання сучасної модельно-орієнтованої технології розробки законів системи автоматичного керування. Розроблено програму моделювання і візуалізації контуру літак-система автоматичного управління. Показано поліпшення точності витримування параметрів системи автоматичного керування. Розглянуто можливість практичного застосування розробленої програми в авіаційній галузі. Використання вказаного підходу дозволить скоротити час на розробку, аналіз і сертифікацію системи автоматичного керуванн

Properties of pattern formation and selection processes in nonequilibrium systems with external fluctuations

We extend the phase field crystal method for nonequilibrium patterning to stochastic systems with external source where transient dynamics is essential. It was shown that at short time scales the system manifests pattern selection processes. These processes are studied by means of the structure function dynamics analysis. Nonequilibrium pattern-forming transitions are analyzed by means of numerical simulations.Comment: 15 poages, 8 figure

On the local birth place of Geminga

Using estimates of the distance and proper motion of Geminga and the constraints on its radial velocity posed by the shape of its bow shock, we investigate its birth place by tracing its space motion backwards in time. Our results exclude the lambda Ori association as the origin site because of the large distance between both objects at any time. Our simulations place the birth region at approximately 90-240 pc from the Sun, between 197 degrees and 199 degrees in Galactic longitude and -16 degrees and -8 degrees in latitude, most probably inside the Cas-Tau OB association or the Ori OB1a association. We discard the possibility of the progenitor being a massive field star. The association of Geminga with either stellar association implies an upper limit of M = 15 Msun for the mass of its progenitor. We also propose new members for the Cas-Tau and Ori OB1 associations.Comment: 6 pages, 5 figures. Accepted for publication in Astronomy & Astrophysic

Relaxation of energetic S(1D) atoms in Xe gas: Comparison of ab initio calculations with experimental data

In this paper, we report our investigation of the translational energy relaxation of fast S((1)D) atoms in a Xe thermal bath. The interaction potential of Xe-S was constructed using ab initio methods. Total and differential cross sections were then calculated. The latter have been incorporated into the construction of the kernel of the Boltzmann equation describing the energy relaxation process. The solution of the Boltzmann equation was obtained and results were compared with those reported in experiments [G. Nan, and P. L. Houston, J. Chem. Phys. 97, 7865 (1992)]. Good agreement with the measured time-dependent relative velocity of fast S((1)D) atoms was obtained except at long relaxation times. The discrepancy may be due to the error accumulation caused by the use of hard sphere approximation and the Monte Carlo analysis of the experimental data. Our accurate description of the energy relaxation process led to an increase in the number of collisions required to achieve equilibrium by an order of magnitude compared to the number given by the hard-sphere approximation.Astronom

Selecting Mathematical Software for Dependability Assessment of Computer Systems Described by Stiff Markov Chains

Markov and semi-Markov models are widely used in dependability assessment of complex computer-based systems. Model stiffness poses a serious problem both in terms of computational difficulties and in terms of accuracy of the assessment. Selecting an appropriate method and software package for solving stiff Markov models proved to be a non-trivial task. In this paper we provide an empirical comparison of two approaches to dealing with stiffness – stiffness avoidance and stiffness-tolerance. The study includes several well known techniques and software tools used for solving Kolmogorov’s differential equations derived from complex stiff Markov models. In the comparison we used realistic cases studies developed by others in the past: i) a computer system with hardware redundancy and diverse software, and ii) a queuing system with a server break-down and repair. The results indicate that the accuracy of the known methods is significantly affected by the stiffness of the Markov models, which led us to developing a procedure (an algorithm) for selecting the optimal method and tool for solving a given stiff Markov model. The algorithm is, also included in the paper