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71.
Nonlinear ion-acoustic solitary waves in an electron-positron-ion plasma with relativistic positron beam
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The propagation characteristics of nonlinear ion–acoustic(IA) solitary waves(SWs) are studied in thermal electron–positron–ion plasma considering the effect of relativistic positron beam. Starting from a set of fluid equations and using the reductive perturbation technique, we derive a Korteweg–de Vries(KdV) equation which governs the evolution of weakly nonlinear IA SWs in relativistic beam driven plasmas. The properties of the IA soliton are studied, and it is shown that the presence of relativistic positron beam significantly modifies the characteristics of IA solitons. 相似文献
72.
Y. Rama Krishna Sarma 《Annals of the Institute of Statistical Mathematics》1987,39(1):497-512
Summary In this note some asymptotically optimum tests for testing hypotheses concerning parameters when the observations are dependent
are obtained. Test statistics based on the score functions, similar to the one proposed by Rao in the case when the observations
are i.i.d. are proposed. Asymptotically UMP tests for one sided hypotheses against one sided alternatives and asymptotically
UMP unbiased test for a simple hypothesis against two sided alternatives are derived. In the multiparameter case tests for
simple hypotheses that have asymptotically best constant power on some family of surfaces in the parameter space are derived. 相似文献
73.
Biswanath Das Kongara Ravinder Reddy Bommena Ravikanth Akella Venkata Subrahmanya Sarma Balasubramanian Sridhar 《Helvetica chimica acta》2008,91(6):1137-1143
Chemical investigation on two samples of the flowers of Parthenium hysterophorus afforded two new pseudoguaianolides (one from each sample) together with several known constituents. The structures of the new compounds were established by extensive spectroscopic (1D‐ and 2D‐NMR) studies. The X‐ray crystallographic analysis of one of these compounds was also accomplished. 相似文献
74.
The data on the excitation functions of20Ne(16O,12C)24Mg,20Ne(16O,12C)24Mg*(1.37, 2+),20Ne(16O,12C)24Mg*(4.12, 4++4.24, 2+) +20Ne(16O,12C*(4.44, 2+))24Mg,20Ne(16O,12C)24Mg*(6.01, 4++6.43, 0+),20Ne(16O,20Ne)16O,20Ne(16O,20Ne*(1.63, 2+))16O, and20Ne(16O,20Ne*(4.25, 4+))16O reactions atθ lab=13° fromE c.m.=22.8 to 38.6 MeV have been subjected to a statistical analysis comprising of the calculations of the distribution of cross sections, deviation functions, cross-correlation functions, summed excitation functions, cross-channel correlation coefficients and coherence widths. The analysis confirms the existence of nonstatistical structures atE c.m.=24.6, 27.8, 31.7 and 35.5 MeV, and identifies a new structure of the same nature atE c.m. =25.6 MeV. 相似文献
75.
In this paper we consider the plasma maser theory of whistler waves in the presence of ion cyclotron waves in a magnetized plasma. In a plasma with low frequency ion cyclotron turbulence and a high frequency test whistler wave, growth of the whistler wave takes place because of the turbulent bremsstrahlung interaction between the resonant electrons and the modulated electric fields. The growth rate of the whistler wave is calculated and the results discussed. 相似文献
76.
The condensation of benzene 1,3,5-tricarbonylchloride with cystine-di-Me [H2N-CH(COOMe)-CH2-S-S-CH2-CH(COOMe)-NH2] yielded triply bridged (1,3,5) cyclophane 1, which was shown by detailed spectral studies and molecular orbital calculations to have a D3 symmetry with conformationally identical linkers and a spherical topology. In sharp contrast, the (1,3,5) cyclophane 2 from the rarely studied lanthionine di-Me [H2N-CH(COOMe)-CH2-S-CH2-CH(COOMe)-NH2], showed only a equatorial twofold symmetry. This work highlights the special properties of the -S-S- bridge in cystine, which makes it an exceptional synthon in nature and organic synthesis. 相似文献
77.
Rupam Sarma Pradip Chowdhury Chaitanya Bikkina Sasidhar Gumma Jubaraj B. Baruah 《Journal of chemical crystallography》2010,40(10):892-896
Abstract
The structural aspects of one-dimensional coordination polymer (1) of nickel(II) with 1,3,5-benzene tricarboxylate and a three-dimensional interpenetrating coordination polymer (2) of zinc(II) with 1,4-benzenedicarboxylate ligand are studied by single crystal X-ray diffraction analysis. Coordination polymer (1) forms a hydrogen bonded three dimensional network structures. The coordination polymer 1 having a composition [Ni3(TMA)2(H2O)12] n where (TMA = trimesate anion), crystallizes in monoclinic crystal system with C2 space group and has a/?, 17.3387(4); b/?, 12.8748(4); c/?, 6.5302(2); β/°111.620(2); V/?3, 1355.20(7). The zinc coordination polymer 2 crystal system is orthorhombic, with space group Pbca. It has a/?, 14.5049(3); b/?, 17.1616(3); c/?, 18.1389(4); V/?3, 4515.27(16). The 1,4-benzenedicarboxylate three dimensional coordination polymer of zinc(II) comprises of novel hydroxo bridged tetranuclear zinc(II) secondary building units and has a composition [Zn2(C6H4C2O4)1.5{(CH3)2SO}2(OH)] n . Topological analysis of the three dimensional coordination polymer 2 shows that it has a two fold interpenetrating net topology. 相似文献78.
The data on the excitation functions of24Mg+28Si elastic and inelastic (2+ ?0+, 2+ ?2+, 4+ ?0+ and 4+ ?2+) scattering fromE c.m.=48.97 to 57.21 MeV have been subjected to a statistical analysis consisting of the calculations of deviation function, cross-correlation function, summed excitation function, cross-channel correlation coefficients, coherence widths, and the distribution of cross sections. Based on the outcome of the analysis resonant structures atE c.m.=49.23, 50.02, 50.51, 52.10, 52.53, 53.27 and 54.14 MeV have been confirmed and three new structures of the same nature have been identified atE c.m.=51.42, 54.88 and 55.60 MeV. 相似文献
79.
We theoretically study the observable response of edge currents in two-dimensional cold atom optical lattices. As an example, we use Gutzwiller mean-field theory to relate persistent edge currents surrounding a Mott insulator in a slowly rotating trapped Bose-Hubbard system to time of flight measurements. We briefly discuss an application, the detection of the Chern number using edge currents of a topologically ordered optical lattice insulator. 相似文献
80.
Sarma DD Ray S Tanaka K Kobayashi M Fujimori A Sanyal P Krishnamurthy HR Dasgupta C 《Physical review letters》2007,98(15):157205
We present magnetization (M) and magnetoresistance (MR) data for a series of Sr2FeMoO6 samples with independent control on antisite defect and grain-boundary densities, which reveal several unexpected features, including a novel switching-like behavior of MR with M. These, in conjunction with model calculations, establish that the MR in Sr2FeMoO6 is dominantly controlled by a new mechanism, derived from the magnetic polarization of grain-boundary regions acting like spin valves, leading to behavior qualitatively different from that usually encountered in tunneling MR. We show that a simple and useful experimental signature for the presence of this spin-valve-type MR (SVMR) is a wider hysteresis in MR compared to that in M. 相似文献