5,450 research outputs found
The Formation of Low-Mass Double White Dwarfs through an Initial Phase of Stable Non-Conservative Mass Transfer
Although many double white dwarfs (DWDs) have been observed, the evolutionary
channel by which they are formed from low-mass/long-period
red-giant-main-sequence (RG-MS) binaries remains uncertain. The canonical
explanations involve some variant of double common-envelope (CE) evolution,
however it has been found that such a mechanism cannot produce the observed
distribution. We present a model for the initial episode of mass transfer (MT)
in RG-MS binaries, and demonstrate that their evolution into double white
dwarfs need not arise through a double-CE process, as long as the initial
primary's core mass (Md,c) does not exceed 0.46M. Instead, the first
episode of dramatic mass loss may be stable, non-conservative MT. We find a
lower bound on the fraction of transferred mass that must be lost from the
system in order to provide for MT, and demonstrate the feasibility of this
channel in producing observed low-mass (with M < 0.46M) DWD
systems.Comment: 2 pages, 1 figure, Conference Proceedings for the International
Conference on Binaries, Mykonos, Greec
Six-loop expansion study of three-dimensional -vector model with cubic anisotropy
The six-loop expansions of the renormalization-group functions of
-vector model with cubic anisotropy are calculated within the minimal
subtraction (MS) scheme in dimensions. The
expansions for the cubic fixed point coordinates, critical exponents
corresponding to the cubic universality class and marginal order parameter
dimensionality separating different regimes of critical behavior are
presented. Since the expansions are divergent numerical estimates
of the quantities of interest are obtained employing proper resummation
techniques. The numbers found are compared with their counterparts obtained
earlier within various field-theoretical approaches and by lattice
calculations. In particular, our analysis of strengthens the existing
arguments in favor of stability of the cubic fixed point in the physical case
On the estimate of the sigma^(I = 1)_(KN)(0)-term value from the energy level shift of kaonic hydrogen in the ground state
Using the experimental data on the energy level shift of kaonic hydrogen in
the ground state (the DEAR Collaboration, Phys. Rev. Lett. 94, 212302 (2005))
and the theoretical value of the energy level shift, calculated within the
phenomenological quantum field theoretic approach to the description of strong
low-energy anti-K N and anti-K NN interactions developed at Stefan Meyer
Institut fuer subatomare Physik in Vienna, we estimate the value of the
sigma^(I = 1)_(KN)(0)-term of low-energy anti-K N scattering. We get sigma^(I =
1)_(KN)(0) = (433 +/- 85) MeV. This testifies the absence of strange quarks in
the proton structure.Comment: 7 pages, no figure
METHODOLOGICAL ASPECTS IN TRAINING BUSINESS PEOPLE: ENGLISH DECLARATIVE SENTENCES INTONATION CONTOURS IN BUSINESS NEGOTIATIONS
Spatial transformation as an institutional factor of the public management of macroeconomic systems
Purpose: The article analyzes the issue of substantiating the impact of the spatial organization of the territory of the Russian Federation on the public management at the level of macroeconomic systems. Design/Methodology/Approach: The federal districts were chosen as the object of the study as macro-regional socio-economic systems, the Southern Federal District and its constituent regions (subjects of the Russian Federation). The article investigates the main transformational processes taking place in the RF spatial development, concerning the development of the regional systems of the public management and the necessity of their consistency at the supra-regional (macro-regional) level. Findings: The authors propose a set of measures to form supra-regional system to coordinate the regional development priorities considering the peculiarities of the spatial transformation of Russia's territory and the position of the Southern macro-region in the spatial system of the country. This system formation allows involving as many interested parties as possible. Practical Implications: The results may be implemented into macro-region public administration to maximize the advantages of the geo-economic and strategic position, natural and climatic conditions of Russian regions' development. Originality/Value: The main contribution of this study is a tailored approach to the public administration of the social and economic development of the macro-regions in the context of the spatial transformation.peer-reviewe
Supernova Ia: a Converging Delayed Detonation Wave
A model of a carbon-oxygen (C--O) presupernova core with an initial mass 1.33
M_\odot, an initial carbon mass fraction 0.27, and with an average mass
growth-rate 5 x 10^{-7} M_\odot/yr due to accretion in a binary system was
evolved from initial central density 10^9 g/cm^3, and temperature 2.05 x 10^8 K
through convective core formation and its subsequent expansion to the carbon
runaway at the center. The only thermonuclear reaction contained in the
equations of evolution and runaway was the carbon burning reaction 12C + 12C
with an energy release corresponding to the full transition of carbon and
oxygen (with the same rate as carbon) into 56Ni. As a parameter we take
\alpha_c - a ratio of a mixing length to the size of the convective zone. In
spite of the crude assumptions, we obtained a pattern of the runaway acceptable
for the supernova theory with the strong dependence of its duration on
\alpha_c. In the variants with large enough values of \alpha_c=4.0 x 10^{-3}
and 3.0 x 10^{-3} the fuel combustion occurred from the very beginning as a
prompt detonation. In the range of 2.0 x 10^{-3} >= \alpha_c >= 3.0 x 10^{-4}
the burning started as a deflagration with excitation of stellar pulsations
with growing amplitude. Eventually, the detonation set in, which was activated
near the surface layers of the presupernova (with m about 1.33 M_\odot) and
penetrated into the star down to the deflagration front. Excitation of model
pulsations and formation of a detonation front are described in detail for the
variant with \alpha_c=1.0 x 10^{-3}.Comment: 13 pages, 11 figures, to appear in Astronomy Letter
The priority choice in the process of strategy working-out of the social economic micro region development
The development of the social economic strategies progress of the micro region namely the choice of priority industries which progress is to be supported by the authorities.
The given article provides detailed description of a special authors’ approach how to analyze of perceptivity investment level into different sectors in frames of strategies working-out of the social economic development of the micro region.
This approach is based on the creation of a special scale within its formation special attention is paid to the identification of the life cycle stage of the industry under analyses besides the potential development possibility of industries available for resources usage.peer-reviewe
Group analysis and exact solutions of a class of variable coefficient nonlinear telegraph equations
A complete group classification of a class of variable coefficient
(1+1)-dimensional telegraph equations , is
given, by using a compatibility method and additional equivalence
transformations. A number of new interesting nonlinear invariant models which
have non-trivial invariance algebras are obtained. Furthermore, the possible
additional equivalence transformations between equations from the class under
consideration are investigated. Exact solutions of special forms of these
equations are also constructed via classical Lie method and generalized
conditional transformations. Local conservation laws with characteristics of
order 0 of the class under consideration are classified with respect to the
group of equivalence transformations.Comment: 23 page
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