4,565 research outputs found
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
Scientific approaches to the reasearches of parenthood and rejection of it
In the article intercommunication is examined biological, psychological and social factors in scientific approaches of research of paternalness and abandonment from him.В статье рассматривается взаимосвязь биологического, психологического и социального факторов в научных подходах исследования родительства и отказа от него
Third-order many-body perturbation theory calculations for the beryllium and magnesium isoelectronic sequences
Relativistic third-order MBPT is applied to obtain energies of ions with two
valence electrons in the no virtual-pair approximation (NVPA). A total of 302
third-order Goldstone diagrams are organized into 12 one-body and 23 two-body
terms. Only third-order two-body terms and diagrams are presented here, owing
to the fact that the one-body terms are identical to the previously studied
third-order terms in monovalent ions. Dominant classes of diagrams are
identified. The model potential is a Dirac-Hartree-Fock potential,
and B-spline basis functions in a cavity of finite radius are employed in the
numerical calculations. The Breit interaction is taken into account through
second order of perturbation theory and the lowest-order Lamb shift is also
evaluated. Sample calculations are performed for berylliumlike ions with Z =
4--7, and for the magnesiumlike ion P IV. The third-order energies are in
excellent agreement with measurement with an accuracy at 0.2% level for the
cases considered. Comparisons are made with previous second-order MBPT results
and with other calculations. The third-order energy correction is shown to be
significant, improving second-order correlation energies by an order of
magnitude
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Origin of the ungrouped achondrite NWA 4518: mineralogy and geochemistry of FeNi-metal
Ungrouped achondrite NWA 4518 is an ultramafic breccia with abundant siderophile rich IIA-like metal. Its silicate chemistry is similar to that of WINs, HEDs, and silicate inclusions of IIE irons. Oxygen isotopic composition is nearby IAB-IIICD-WIN
Plasma-mediated Nanosecond-Laser Generation of Si Nanoparticles in Water
Plasma-mediated nanosecond IR-laser ablation of Si in water was describe sublinear function mass loss by multi shot ablative and third-power function extinction coefficient of generated colloidal solutions of density laser intensity. The first addiction shows influence subcritical ablative plasma to ablative rate, also fast increase extinction coefficient of 100 nm size particles of silicon in colloidal solution implies plasma-mediated dissociation of the ablation products.
Keywords: silicon nanoparticles, nanosecond laser ablation, sub-critical ablative plasma, extinction coefficient, scaling relationships, melt expulsio
Increasing the budget costs’ efficiency as a factor of state finance stabilization
The article stands for comprehensive system approach in increasing the effect and performance of budget costs, providing the stability and long-term sustainability of state finance. In recent times Russia has gone to considerable lengths in introduction of result-oriented budgeting both on federal and regional level. In a similar vein, we could highlight the fact that insufficient conditions are created to increase the efficiency of budget costs management.
The research paid much attention to the issues connected with evaluation of budget costs’ performance in conditions of implementing the concept of budget consolidation and budget constraints. Authors set number of objectives: studying economic essence of “efficiency” and “performance” of budget expenditures; studying the framework of budget stabilization financial support measures; revealing the methodological approaches in budget cost effect evaluation in the framework of program-target budgeting including the regional level.
The article concludes with the necessity of improving the evaluation system of criterion-based budget costs’ management as well as highlighting the condition when the positive effect of program-target budgeting is reached: firstly, solving of methodological problem of measuring the planned (target) and actual results of budget funding; secondly, taking measures of strengthening the real responsibility of state authorities for accomplishment of target indicatorspeer-reviewe
Russian Amino Chelate Fertilizers of Agrovin Type Applied on White Cabbage
When applying synthetic chelate fertilizers, the plant ”takes away” only the element of nutrition, and the chelator (as a foreign element, ballast) gets into the soil, where over time, accumulating, creates negative environmental consequences. The use of amino acids in foliar fertilizers is one of the most promising ways to eliminate the impact of harmful environmental conditions on agricultural plants. In addition, consumers have recently been very interested in organic food and have been demanding quality and food safety. Translocation of amino acids takes place both in the phloem and in the xylem, which helps to dispose of nitrogen in the roots and above-ground part of the plant and accelerates the retransmission of nutrients in plants, in particular, fixed elements. The absorption rate of amino acids depends on the biological characteristics of the plants and the characteristics of the amino acids. The research is aimed at determining the influence of leaf fertilizing with amino chelate fertilizers of the Agrovin series on the growth, development and yield of white cabbage
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