INTEGRAL and Swift observations of the hard X-ray transient MAXI J1828-249

In this paper we report on the observations performed with INTEGRAL and Swift of the first outburst detected from the hard X-ray transient MAXI J1828-249. During the first about two days of the outburst, the source was observed by MAXI to undergo a very rapid transition from a hard to a softer spectral state. While the hard state was not efficiently monitored because the transition occurred so rapidly, the evolution of the source outburst in the softer state was covered quasi-simultaneously in a broad energy range (0.6-150 keV) by the instruments on-board INTEGRAL and Swift. During these observations, the spectra measured from the source displayed both a prominent thermal emission with temperature kT 0.7 keV and a power-law hard component with a photon index gamma 2.2 extending to 200 keV. The properties of the source in the X-ray domain are reminiscent of those displayed by black hole transients during the soft intermediate state, which supports the association of MAXI J1828-249 with this class of objects.Comment: 5 pages, 5 figures, 2 tables. Accepter for publication in A&

A non-perturbative proof of Bertrand's theorem

We discuss an alternative non-perturbative proof of Bertrand's theorem that leads in a concise way directly to the two allowed fields: the newtonian and the isotropic harmonic oscillator central fields.Comment: Latex file plus one eps figur

Relation between the X-ray and Optical Luminosities in Binary Systems with Accreting Nonmagnetic White Dwarfs

We investigate the relation between the optical (g-band) and X-ray (0.5-10 keV) luminosities of accreting nonmagnetic white dwarfs. According to the present-day counts of the populations of star systems in our Galaxy, these systems have the highest space density among the close binary systems with white dwarfs. We show that the dependence of the optical luminosity of accreting white dwarfs on their X-ray luminosity forms a fairly narrow one-parameter curve. The typical half-width of this curve does not exceed 0.2-0.3 dex in optical and X-ray luminosities, which is essentially consistent with the amplitude of the aperiodic flux variability for these objects. At X-ray luminosities Lx~1e32 erg/sec or lower, the optical g-band luminosity of the accretion flow is shown to be related to its X-ray luminosity by a factor ~2-3. At even lower X-ray luminosities (Lx~1e30 erg/sec), the contribution from the photosphere of the white dwarf begins to dominate in the optical spectrum of the binary system and its optical brightness does not drop below Mg~13-14. Using the latter fact, we show that in current and planned X-ray sky surveys, the family of accreting nonmagnetic white dwarfs can be completely identified to the distance determined by the sensitivity of an optical sky survey in this region. For the Sloan Digital Sky Survey (SDSS) with a limiting sensitivity m_g~22.5, this distance is ~400-600 pcComment: 7 pages, 3 figures, published in Astronomy Letter

Estimating the cutting force when skiving with a radius cutter

The paper considers the method of determining the components of the cutting force under cutting completed with a radius cutter. The authors provide the design of the experimental study. The authors provide the data on the cutting force change in the process of turning with a radius cutter according to the cutting edge inclination, cutting depth and supply obtained experimentally and calculated analytically. The paper also provides the results of experimental work approximation and theoretical error checking related to experimental data

Experimental estimation of chip shrinkage under cup-tip cutting with straight and radius cutters

In the given work we present the results of experimental estimation of chip shrinkage under turning with straight and radius cutters for two schemes of cutting: "direct" and "reverse". Ratios of thickening, broadening and longitudinal shrinkage of the chip were established as shrinkage parameters. The given paper presents the graphic charts showing dependences of shrinkage upon cutting depth, supply and cutting edge inclination which indicate the deformations taking place in the cutting area when cutting with cup-tip cutters. The authors show the significant difference in the character and degree of chip shrinkage when working according to various schemes of cutting

Влияние стерилизации на свойства трековых мембран из полиэтилентерефталата

В работе представлены результаты исследований трековых мембран из полиэтилентерефталата после паровой стерилизации и стерилизации ионизирующим облучением.Исходя из полученных данных, можно считать, что стерилизация ионизирующим излучениемрадионуклидов Co60 является более предпочтительной, чем паровая стерилизация

Internet use for educational purposes: Evidence from Russia

© 2015, Mediterranean Center of Social and Educational Research. All rights reserved. The study sets out to examine empirically the use of Internet in education process in Russia. Socio-demographic determinants of use of Internet for educational purposes, to obtain reference information or to learn the news are studied. The sample represents entire population of Russia. Significant age and gender differences in Internet use for educational purposes are discovered. Influence of satisfaction with financial status on Internet use is weak, while it is the education level of respondents which acts as the most powerful determinant of Internet use for educational purposes