1,649 research outputs found
International aspects of the Russian Federation responsibility for the breaking of constitutional human rights and liberties
Russia on international liability for violation of constitutional rights and freedomsВоронцова, Ю.А.Хорошко, Е.Ю.Навроцкая, И.Н
A Two-Dimensional MagnetoHydrodynamics Scheme for General Unstructured Grids
We report a new finite-difference scheme for two-dimensional
magnetohydrodynamics (MHD) simulations, with and without rotation, in
unstructured grids with quadrilateral cells. The new scheme is implemented
within the code VULCAN/2D, which already includes radiation-hydrodynamics in
various approximations and can be used with arbitrarily moving meshes (ALE).
The MHD scheme, which consists of cell-centered magnetic field variables,
preserves the nodal finite difference representation of div(\bB) by
construction, and therefore any initially divergence-free field remains
divergence-free through the simulation. In this paper, we describe the new
scheme in detail and present comparisons of VULCAN/2D results with those of the
code ZEUS/2D for several one-dimensional and two-dimensional test problems. The
code now enables two-dimensional simulations of the collapse and explosion of
the rotating, magnetic cores of massive stars. Moreover, it can be used to
simulate the very wide variety of astrophysical problems for which multi-D
radiation-magnetohydrodynamics (RMHD) is relevant.Comment: 22 pages, including 11 figures; Accepted to the Astrophysical
Journal. Higher resolution figures available at
http://zenith.as.arizona.edu/~burrows/mhd-code
Features of the Acoustic Mechanism of Core-Collapse Supernova Explosions
In the context of 2D, axisymmetric, multi-group, radiation/hydrodynamic
simulations of core-collapse supernovae over the full 180 domain, we
present an exploration of the progenitor dependence of the acoustic mechanism
of explosion. All progenitor models we have tested with our Newtonian code
explode. We investigate the roles of the Standing-Accretion-Shock-Instability
(SASI), the excitation of core g-modes, the generation of core acoustic power,
the ejection of matter with r-process potential, the wind-like character of the
explosion, and the fundamental anisotropy of the blasts. We find that the
breaking of spherical symmetry is central to the supernova phenomenon and the
blasts, when top-bottom asymmetric, are self-collimating. We see indications
that the initial explosion energies are larger for the more massive
progenitors, and smaller for the less massive progenitors, and that the
neutrino contribution to the explosion energy may be an increasing function of
progenitor mass. The degree of explosion asymmetry we obtain is completely
consistent with that inferred from the polarization measurements of Type Ic
supernovae. Furthermore, we calculate for the first time the magnitude and sign
of the net impulse on the core due to anisotropic neutrino emission and suggest
that hydrodynamic and neutrino recoils in the context of our asymmetric
explosions afford a natural mechanism for observed pulsar proper motions.
[abridged]Comment: Accepted to the Astrophysical Journal, 23 pages in emulateapj format,
including 12 figure
Innovations in foreign (chinese) students’ grammar competence formation while training them russian as a foreign language: network technology and the module approach
The article deals with the researches in the field of finding new methods of teaching Russian to foreign (Chinese) students and its Grammar aspect, in particular. In this connection the authors share the results of the investigation dealt with the development of one of the most future-oriented approaches in methods of training the Russian Grammar standards which may be called the Module Approach realized by means of Network Technologie
A supersymmetric model for triggering Supernova Ia in isolated white dwarfs
We propose a model for supernovae Ia explosions based on a phase transition
to a supersymmetric state which becomes the active trigger for the deflagration
starting the explosion in an isolated sub-Chandrasekhar white dwarf star. With
two free parameters we fit the rate and several properties of type Ia
supernovae and address the gap in the supermassive black hole mass
distribution. One parameter is a critical density fit to about
g/cc while the other has the units of a space time volume and is found to be of
order Gyr where is the earth radius. The model involves
a phase transition to an exact supersymmetry in a small core of a dense star.Comment: 20 pages, 5 figures, expanded version to be published in Physical
Review
Cosmic Rays from PeV to ZeV, Stellar Evolution, Supernova Physics and Gamma Ray Bursts
The recent success of a proposal from some time ago to explain the spectrum of cosmic rays allows some strong conclusions to be made on the physics of supernovae: In the context of this specific proposal to explain the origin of cosmic rays, the mechanism for exploding supernovae of high mass has to be the one proposed by Bisnovatyi-Kogan more than 30 years ago, which was then based on a broader suggestion by Kardashev: A combination of the effects of rotation and magnetic fields explodes the star. Interestingly, this step then leads inevitably to some further suggestions, useful perhaps for the study of gamma ray bursts and the search of a bright standard candle in cosmology
Linguocultural aspects of the discursive synergy
This article discusses the basic principles of the innovative “discursive synergy of cultural linguistics” concept. The relation of language and culture in the format of linguocultural concept as the basis of linguocultural discourse, which is anonlinear communication model is researchedyesBelgorod State Universit
Turbulent magnetic field amplification from spiral SASI modes in core-collapse supernovae
We describe the initial implementation of magnetohydrodynamics (MHD) in our
astrophysical simulation code \genasis. Then, we present MHD simulations
exploring the capacity of the stationary accretion shock instability (SASI) to
generate magnetic fields by adding a weak magnetic field to an initially
spherically symmetric fluid configuration that models a stalled shock in the
post-bounce supernova environment. Upon perturbation and nonlinear SASI
development, shear flows associated with the spiral SASI mode contributes to a
widespread and turbulent field amplification mechanism. While the SASI may
contribute to neutron star magnetization, these simulations do not show
qualitatively new features in the global evolution of the shock as a result of
SASI-induced magnetic field amplification.Comment: 15 pages, 7 figures, To appear in the Journal of Physics: Conference
Series. Proceedings of the IUPAP Conference on Computational Physics
(CCP2011
Early treatment of posterior crossbite - a randomised clinical trial
Background: The aim of this randomised clinical trial was to assess the effect of early orthodontic treatment in contrast to normal growth effects for functional unilateral posterior crossbite in the late deciduous and early mixed dentition by means of three-dimensional digital model analysis.
Methods: This randomised clinical trial was assessed to analyse the orthodontic treatment effects for patients with functional unilateral posterior crossbite in the late deciduous and early mixed dentition using a two-step procedure: initial maxillary expansion followed by a U-bow activator therapy. In the treatment group 31 patients and in the control group 35 patients with a mean age of 7.3 years (SD 2.1) were monitored. The time between the initial assessment (T1) and the follow-up (T2) was one year. The orthodontic analysis was done by a three-dimensional digital model analysis. Using the ‘Digimodel’ software, the orthodontic measurements in the maxilla and mandible and for the midline deviation, the overjet and overbite were recorded.
Results: Significant differences between the control and the therapy group at T2 were detected for the anterior, median and posterior transversal dimensions of the maxilla, the palatal depth, the palatal base arch length, the maxillary arch length and inclination, the midline deviation, the overjet and the overbite.
Conclusions: Orthodontic treatment of a functional unilateral posterior crossbite with a bonded maxillary expansion device followed by U-bow activator therapy in the late deciduous and early mixed dentition is an effective therapeutic method, as evidenced by the results of this RCT. It leads to three-dimensional therapeutically induced maxillary growth effects. Dental occlusion is significantly improved, and the prognosis for normal craniofacial growth is enhanced
- …
