284 research outputs found
Theory of wind accretion
A review of wind accretion in high-mass X-ray binaries is presented. We focus
attention to different regimes of quasi-spherical accretion onto the neutron
star: the supersonic (Bondi) accretion, which takes place when the captured
matter cools down rapidly and falls supersonically toward NS magnetospghere,
and subsonic (settling) accretion which occurs when plasma remains hot until it
meets the magnetospheric boundary. Two regimes of accretion are separated by an
X-ray luminosity of about erg/s. In the subsonic case, which
sets in at low luminosities, a hot quasi-spherical shell must be formed around
the magnetosphere, and the actual accretion rate onto NS is determined by
ability of the plasma to enter the magnetosphere due to Rayleigh-Taylor
instability. We calculate the rate of plasma entry the magnetopshere and the
angular momentum transfer in the shell due to turbulent viscosity appearing in
the convective differentially rotating shell. We also discuss and calculate the
structure of the magnetospheric boundary layer where the angular momentum
between the rotating magnetosphere and the base of the differentially rotating
quasi-spherical shell takes place. We show how observations of equilibrium
X-ray pulsars Vela X-1 and GX 301-2 can be used to estimate dimensionless
parameters of the subsonic settling accretion theory, and obtain the width of
the magnetospheric boundary layer for these pulsars.Comment: LaTeX, 10 pages, 5 figures; submitted to Proc. of Int. Conf. "Physics
at the Magnetspheric Boundary", Geneva, Switzerland, 25-28 June, 201
Government control of agrarian field of economics in the conditions of global challenge and threats
Political, economic and social importance of agrarian problems in the Russian Federation has received extremely sharp sound associated with ensuring food security, import substitution of food which requires reasonable macroeconomic and financial government management, including the adaptation of modern measures of government regulation of rural development to the new economic conditions. In this regard, the economic science once again faces with the task of understanding and studying of the theoretical positions and methodological approaches to the development of a new agricultural policy, to the search of optimal forms and methods of government influence on the agricultural market, building a system of cooperation between government, business and the peasantry on the basis of maximal coordination of mechanisms of government regulation of the agrarian sector with the motivational structure of the rural population in terms of adaptation to modern agricultural methods and tools of influence. This article contains the argumentation of the provisions on the development of the system of government regulation of the agrarian sector of the Russian economy in the new economic conditions that will ensure import substitution, increase in the competitiveness of Russia in the global food market.peer-reviewe
Tissue-selective expression of a conditionally-active ROCK2-estrogen receptor fusion protein
The serine/threonine kinases ROCK1 and ROCK2 are central mediators of actomyosin contractile force generation that act downstream of the RhoA small GTP-binding protein. As a result, they have key roles in regulating cell morphology and proliferation, and have been implicated in numerous pathological conditions and diseases including hypertension and cancer. Here we describe the generation of a gene-targeted mouse line that enables CRE-inducible expression of a conditionally-active fusion between the ROCK2 kinase domain and the hormone-binding domain of a mutated estrogen receptor (ROCK2:ER). This two-stage system of regulation allows for tissue-selective expression of the ROCK2:ER fusion protein, which then requires administration of estrogen analogues such as tamoxifen or 4-hydroxytamoxifen to elicit kinase activity. This conditional gain-of-function system was validated in multiple tissues by crossing with mice expressing CRE recombinase under the transcriptional control of cytokeratin14 (K14), murine mammary tumor virus (MMTV) or cytochrome P450 Cyp1A1 (Ah) promoters, driving appropriate expression in the epidermis, mammary or intestinal epithelia respectively. Given the interest in ROCK signaling in normal physiology and disease, this mouse line will facilitate research into the consequences of ROCK activation that could be used to complement conditional knockout models
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