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Durant M.,University of Florida | Kargaltsev O.,University of Florida | Pavlov G.G.,Pennsylvania State University | Pavlov G.G.,St Petersburg Polytechnical University
Astrophysical Journal | Year: 2011

We report broadband Hubble Space Telescope imaging of the field of soft γ-ray repeater SGR 0418+5729 with Advanced Camera for Surveys/Wide Field Channel and Wide Field Camera 3/IR. Observing in two wide filters, F606W and F110W, we find no counterpart within the positional error circle derived from Chandra observations, to limiting magnitudes m F606W > 28.6 and m F110W > 27.4 (Vega system), equivalent to reddening-corrected luminosity limits L F606W < 5 × 1028 and L F110W < 6 × 1028ergs-1 for a distance d = 2kpc, at 3σ confidence. This, in turn, imposes lower limits on the contemporaneous X-ray/optical flux ratio of ≃1100 and the X-ray/near-infrared flux ratio of ≃1000. We derive an upper limit on the temperature and/or size of any fall-back disk around the magnetar. We also compare the detection limits with observations of other magnetars. © 2011. The American Astronomical Society. All rights reserved. Source


Kalinin M.O.,St Petersburg Polytechnical University
SIN'10 - Proceedings of the 3rd International Conference of Security of Information and Networks | Year: 2010

Information security is very important nowadays. Every IT system needs protection mechanisms for stability and safety of work. To solve this task, there are proposed a variety of securityproviding solutions, but most of them are very expensive and nonsystematic. The paper discusses up-to-date techniques implemented for security aims and addresses to the technique of security control based on settings monitoring of variable program components of the trusted information environment. There is proposed a formal basis of security control based on finding the security settings which provide the system with stability and integrity. The specified technique allows proposing a schema of dynamic Security and Integrity Control System which provides an automated process of security assurance and management. These security control technique and system extend security-relevant approaches making security reachable, permanent, and effective. Copyright 2010 ACM. Source


Schrange-Kashenock G.,St Petersburg Polytechnical University
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2016

The first theoretical investigation of the inner-shell single-photodetachment from the Si- (1s22s22p63s23p3 4So) negative ion is presented. The partial and total cross sections, the photoelectron phaseshifts, and the parameters of angular anisotropy are calculated in the framework of the many-body theory for L-shell photodetachment from Si- ion in the experimentally accessible range of photon energies (7.5-14 Ry). Comparison is made between the calculations of the response of the ionic many-electron system Si- to an electromagnetic field at the different levels of approximation: the 'frozen-field' random phase approximation with exchange (RPAE), and the static relaxation approximation. The optimal analysis is made when the dynamic relaxation and polarization are included within the Dyson equation method (DEM) simultaneously with the RPAE corrections (the RPAE&DEM approach). It is predicted that the photoexcitation to a resonance state of complex 'shape-Feschbach' nature in the open p-shell reveals itself as a prominent resonance structure in the photodetachment cross sections in the energy range of the 2s and 2p inner shell thresholds similar to that in 1s inner-shell photodetachment from C- (2006 J. Phys. B: At. Mol. Opt. Phys. 39 1379). The photodetachment dynamical characteristics clearly demonstrate the significance of all the considered many-electron correlations within the RPAE&DEM approach, however the total photodetachment cross section is dominated by a strong resonance peak just after the 2s threshold. Dynamical relaxation (screening) is identified as a decisive factor in the formation of this resonance. © 2016 IOP Publishing Ltd. Source


Durant M.,University of Florida | Kargaltsev O.,University of Florida | Pavlov G.G.,Pennsylvania State University | Pavlov G.G.,St Petersburg Polytechnical University | And 5 more authors.
Astrophysical Journal | Year: 2012

We present extensive spectral and photometric observations of the recycled pulsar/white dwarf binary containing PSR J0437-4715, which we analyzed together with archival X-ray and gamma-ray data, to obtain the complete mid-infrared to gamma-ray spectrum. We first fit each part of the spectrum separately, and then the whole multi-wavelength spectrum. We find that the optical-infrared part of the spectrum is well fit by a cool white dwarf atmosphere model with pure hydrogen composition. The model atmosphere (T eff = 3950 150K, log g = 6.98 ± 0.15, R WD = (1.9 ± 0.2) × 10 9cm) fits our spectral data remarkably well for the known mass and distance (M = 0.25 ± 0.02 M, d = 156.3 ± 1.3pc), yielding the white dwarf age (τWD = 6.0 ± 0.5Gyr). In the UV, we find a spectral shape consistent with thermal emission from the bulk of the neutron star surface, with surface temperature between 1.25 × 105 and 3.5 × 105K. The temperature of the thermal spectrum suggests that some heating mechanism operates throughout the life of the neutron star. The temperature distribution on the neutron star surface is non-uniform. In the X-rays, we confirm the presence of a high-energy tail which is consistent with a continuation of the cutoff power-law component (Γ = 1.56 ± 0.01, E cut = 1.1 ± 0.2GeV) that is seen in gamma rays and perhaps even extends to the near-UV. © 2012. The American Astronomical Society. All rights reserved. Source


Tsendin L.D.,St Petersburg Polytechnical University
Plasma Sources Science and Technology | Year: 2011

Combined experimental, numerical and analytical approaches are presented to address actual problems of glow discharge physics. Such a synthesis is able to clarify relatively simple, qualitative, self-consistent phenomena, and should allow improvement of the existing paradigms and/or formulation of novel approaches. The following illustrative examples are discussed: Linear and non-linear diffusion in multispecies, currentless and current-carrying low-temperature plasmas. Both ambipolar diffusion and ambipolar mobility are considered. Non-local electron kinetics in radio frequency and direct current glows. Structures of the cathode and anode regions in direct current glows. © 2011 IOP Publishing Ltd. Source

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