On uniform permutations with finite dispersion parameters

We study the group G of uniform permutations of the set of integers with finite dispersion parameters. We prove that every finite subset of G lies in a subgroup of the form Q = AB, where A and B are locally finitely approximable subgroups of G.     

Scientific tasks and present status of the GAMMA-400 project

The GAMMA-400 telescope is designed to investigate discrete high-energy gamma-ray sources in the energy range of 0.1–3000 GeV, to measure the energy spectra of galactic and extragalactic diffuse gammaray emissions, and to study gamma-ray bursts and gamma-ray emissions from an active Sun. The gamma-ray telescope has an angular resolution of ～0.01°, an energy resolution of ～1%, and a proton rejection factor of ～10⁶. Its special assignment is to measure fluxes of gamma rays, electrons, and positrons that could be associated with the annihilation or decay of dark matter particles.     

On Classes of Infinite Groups with Involutions

We present a short review of the recent results about infinite groups with given strongly insolated, strongly embedded subgroups and Zassenhaus groups. This research is supported by Krasnoyarsk Science Foundation, grant 11F202C, the Russian Foundation for Basic Research, grant 03-01-00356.Mathematics Subject Classifications (2000) 20B07, 20B22.     

GAMMA-400 Gamma-Ray Observations in the GeV and TeV Energy Range

Physics of Atomic Nuclei - The future space-based GAMMA-400 $$\gamma$$ -ray telescope will operate onboard the Russian astrophysical observatory in a highly elliptic orbit during 7 years. Observing...     

Computational and experimental study of the two-phase mixing in gas-dynamic ignition system

The work is devoted to the determination of main peculiarities of the two-phase mixture formation in the flow duct of the gas-dynamic ignition system. The paper presents a mathematical model and the results of a numerical and experimental investigation of the peculiarities of the unsteady gas flow as well as the processes of the fragmentation and evaporation of droplets in the resonance cavity of the gas-dynamic ignition system. Different configurations of injectors for liquid supply are considered, and the influence of the most significant factors on heat release and concentration of the evaporated liquid in the resonance cavity is investigated. The obtained data may be used for choosing the injectors and the regimes of the liquid fuel supply, which enable one to ensure the stable conditions for igniting two-phase fuel mixtures in the gas-dynamic ignition system.     

Precision Measurements of High-Energy Cosmic Gamma-Ray Emission with the GAMMA-400 Gamma-Ray Telescope

The GAMMA-400 γ-ray telescope installed at the Russian space observatory is intended for precision measurements in the energy range of 20 MeV–1000 GeV of γ-ray emission (with the angular and energy resolutions several times better than that of current γ-ray telescopes) from discrete sources; measurement of the energy spectra of Galactic and extragalactic diffuse γ-ray emission; studies of γ-ray emission from the active Sun; and measurements of fluxes of γ-ray emission and electron–positron cosmicray component, which are probably associated with the annihilation or decay of dark-matter particles.     

Finiteness of Some Sharply Doubly Transitive Groups

Let G be a doubly transitive permutation group such that its point stabilizer is a 2-group and its two-point stabilizer is trivial. It is proved that G is finite and isomorphic to a Frobenius group of order 3²· 2³ or p· 2ⁿ, where p=2ⁿ+1 is a Fermat prime.