Details of the spatial structure and kinematics of the Castor and Ursa Major streams

A list of the Castor stream members is compiled based on the data from various authors. The membership probabilities for some stars are revised based on the individual apex, multiplicity, observational errors, and peculiarity. The apex of the Castor moving group is determined using the apex diagram method. The parameters of the Castor and Ursa Major streams are compared and the positions of the two streams on the apex diagram are found to differ by 225deg, implying that the two groups move in almost opposite directions. Stars of both moving groups are intermixed in space, the Castor stream occupies a smaller volume than the UMa stream and is located inside it. Our results can be useful for understanding the morphology of the Galactic disk in the Sun's vicinity

Radial velocity dispersions of star groups in M 67

High-precision measurements of radial velocities of the M 67 cluster members are used to calculate the radial-velocity dispersions in the stellar groups found earlier in the cluster's corona. The previously detected feature in one of the groups (Group 60) consisting of stars with almost identical space velocities was confirmed. The possibility of more accurate future studies of the parameters of star groups using the Gaia catalogues is discussed.Comment: 7 pages, 2 figure

Algorithmic statistics: forty years later

Algorithmic statistics has two different (and almost orthogonal) motivations. From the philosophical point of view, it tries to formalize how the statistics works and why some statistical models are better than others. After this notion of a "good model" is introduced, a natural question arises: it is possible that for some piece of data there is no good model? If yes, how often these bad ("non-stochastic") data appear "in real life"? Another, more technical motivation comes from algorithmic information theory. In this theory a notion of complexity of a finite object (=amount of information in this object) is introduced; it assigns to every object some number, called its algorithmic complexity (or Kolmogorov complexity). Algorithmic statistic provides a more fine-grained classification: for each finite object some curve is defined that characterizes its behavior. It turns out that several different definitions give (approximately) the same curve. In this survey we try to provide an exposition of the main results in the field (including full proofs for the most important ones), as well as some historical comments. We assume that the reader is familiar with the main notions of algorithmic information (Kolmogorov complexity) theory.Comment: Missing proofs adde

Influence of synthesis conditions on the crystallinity of hydroxyapatite obtained by chemical deposition

The hydroxyapatite synthesis on a variety of substrates under various conditions was studied. It was shown that the increase in the temperature of the reaction medium increases the amount of nanocrystalline phase with an average crystallite size of 25 nm. Studies revealed that in addition to the pure hydroxyapatite, [beta]-Ca[3](PO[4])[2] along with calcium carbonates and carbonate-substituted hydroxyapatites were formed. A significant increase in phase crystallinity during the heating of reactants up to the reaction temperature was shown

Approach of the NGC 1977 star cluster to the TOI-2796 host star

We study of possible encounters in past epochs of the open star cluster NGC 1977 with host stars. For this purpose, the age of the cluster was determined based on our catalog data. Stars with planetary systems were selected from the NASA Archive. The age of the cluster was determined using the color - absolute magnitude diagram and the isochron system. By extending the track of the movement of the cluster and stars in past epochs, 10 Myr. The time of the maximum approach 32 pc of the host star with planetary system TOI-2796 with the NGC 1977 are found. The place of approach in the sky is shown, this point can be considered as the place of appearance of interstellar comets. Thus, the result of our work is that the we found approach of the host star to the cluster entailed effects associated with the gravitational influence of the cluster on the nuclei of comets located in the outer parts of the Oort cloud of the planetary system. The effect of approach on comets is estimated

Chemistry for Sustainable Development 16 (2008) 521-528 Content of Various Size and Density Particles in Cenosphere Concentrates of Volatile Coal Combustion Ashes from the Kuznetsk Coalfield

Abstract Using an aerodynamic method with the subsequent particle size analysis of the fractions obtained a separation process was carried out for cenosphere concentrates from volatile ashes of the Kuznetsk field coal combustion at the Moscow Thermal and Electric Plant TETs-22, the Belovo State Regional Power Station as well as for several cenosphere concentrate fractions obtained at the Novosibirsk Thermal and Electric Plant TETs-5. As much as 90 fractions with the various particle size (70-250 mm) and bulk density (0.16-0.52 g/cm 3 ) have been isolated from the concentrate of the Moscow TETs-22. Irrespective of particle size the bulk density of fractions with the maximal yield is equal to 0.33-0.35g/cm 3 , whereas the ratio of the apparent wall thickness to the particle diameter amounts to 0.042-0.043. The process of the aerodynamic separation of cenospheres from different concentrate sources can be satisfactorily described by theoretical dependences for the carryover of spherical particles; the deviations are caused, first of all, by a nonspherical shape of cenospheres