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101.
Cosmological models with variable G in C-field cosmology for barotropic fluid distribution in FRW space-time are investigated. To get the deterministic model of the
universe, we have assumed that G=R
n
where R is the scale factor and n the constant. To obtain the results in terms of cosmic time t, we have assumed n=−1. We find that for n=−1, Creation field (C) and spatial volume increase with time, G and ρ (matter density) decreases with time, the model represent accelerating universe. Thus inflationary scenario exists in the
model. The model is also free from horizon. The results so obtained match with the astronomical observations. 相似文献
102.
H. Naik P. M. Prajapati S. V. Suryanarayana P. N. Pathak D. R. Prabhu V. Chavan D. Raj P. C. Kalsi A. Goswami S. Ganesan V. K. Manchanda 《The European Physical Journal A - Hadrons and Nuclei》2011,47(8):1-5
The νp process is a primary nucleosynthesis process which occurs in core-collapse supernovae. An essential role in this process is being played by electron antineutrinos. They generate, by absorption on protons, a supply of neutrons which, by (n, p) reactions, allow to overcome waiting point nuclei with rather long beta-decay and proton-capture lifetimes. The synthesis of heavy elements by the νp process depends sensitively on the $\bar \nu _e$ luminosity and spectrum. As has been shown recently, the latter are affected by collective neutrino flavor oscillations which can swap the $\bar \nu _e$ and $\bar \nu _{\mu ,\tau }$ spectra above a certain split energy. Assuming such a swap scenario, we have studied the impact of collective neutrino flavor oscillations on the νp-process nucleosynthesis. Our results show that the production of light p-nuclei up to mass number A = 108 is very sensitive to collective neutrino oscillations. 相似文献
103.
D.M. Raj KumarM. Manivel Raja K. PrabaharV. Chandrasekaran Asok PoddarR. Ranganathan K.G. Suresh 《Journal of magnetism and magnetic materials》2011,323(13):1750-1754
The effect of Si/Ge ratio on resistivity and thermopower behavior has been investigated in the magnetocaloric ferromagnetic Gd5SixGe4−x compounds with x=1.7-2.3. Microstructural studies reveal the presence of Gd5(Si,Ge)4-matrix phase (5:4-type) along with traces of secondary phases (5:5 or 5:3-type). The x=1.7 and 2.0 samples display the presence of a first order structural transition from orthorhombic to monoclinic phase followed by a magnetic transition of the monoclinic phase. The alloys with x=2.2 and 2.3 display only magnetic transitions of the orthorhombic phase. A low temperature feature apparent in the AC susceptibility and resistivity data below 100 K reflects an antiferromagnetic transition of secondary phase(s) present in these compounds. The resistivity behavior study correlates with microstructural studies. A large change in thermopower of −8 μV/K was obtained at the magneto-structural transition for the x=2 compound. 相似文献
104.
We study the complexity of determining whether a polytope given by its vertices or facets is combinatorially isomorphic to its polar dual. We prove that this problem is Graph Isomorphism hard, and that it is Graph Isomorphism complete if and only if Vertex Enumeration is Graph Isomorphism easy. To the best of our knowledge, this is the first problem that is not equivalent to Vertex Enumeration and whose complexity status has a non-trivial impact on the complexity of Vertex Enumeration irrespective of whether checking Self-duality turns out to be strictly harder than Graph Isomorphism or equivalent to Graph Isomorphism. The constructions employed in the proof yield a class of self-dual polytopes that are interesting on their own. In particular, this class of self-dual polytopes has the property that the facet-vertex incident matrix of the polytope is transposable if and only if the matrix is symmetrizable as well. As a consequence of this construction, we also prove that checking self-duality of a polytope, given by its facet-vertex incidence matrix, is Graph Isomorphism complete, thereby answering a question of Kaibel and Schwartz. 相似文献
105.
106.
S. Shanmuga Sundara Raj Hoong‐Kun Fun Jing Zhang Ren‐Geng Xiong Xiao‐Zeng You 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):e274-e275
In the crystal structure of the title compound, C12H10N4, the pyridine ring makes a dihedral angle of 1.12 (9)° with the mean plane of the complete almost planar and crystallographically centrosymmetric molecule. There are stacks of parallel molecules along the a‐axis direction, with alternate stacks having a herring‐bone arrangement relative to each other and an interplanar spacing of 3.551 Å. 相似文献
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