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991.
Pisheng Ding 《Transactions of the American Mathematical Society》2006,358(9):3937-3967
Given a smooth closed -manifold , this article studies the extent to which certain numbers of the form are determined by the fixed-point set , where classifies the universal cover of , , is a polynomial in the Pontrjagin classes of , and is in the subalgebra of generated by . When , various vanishing theorems follow, giving obstructions to certain fixed-point-free actions. For example, if a fixed-point-free -action extends to an action by some semisimple compact Lie group , then . Similar vanishing results are obtained for spin manifolds admitting certain -actions.
992.
John G Hartnett 《International Journal of Theoretical Physics》2006,45(11):2118-2136
Equations of motion, in cylindrical co-ordinates, for the observed rotation of gases within the gravitational potential of spiral galaxies have been derived from Carmeli's Cosmological General Relativity theory. A Tully-Fisher type relation results and rotation curves are reproduced without the need for non-baryonic halo dark matter. Two acceleration regimes are discovered that are separated by a critical acceleration m s−2. For accelerations larger than the critical value the Newtonian force law applies, but for accelerations less than the critical value the Carmelian regime applies. In the Newtonian regime the accelerations fall off as r
−2, but in the Carmelian regime the accelerations fall off as r
−1. This is new physics but is exactly what is suggested by Milgrom's phenomenological MOND theory. 相似文献
993.
O. W. Greenberg 《Foundations of Physics》2006,36(10):1535-1553
Lüders and Pauli proved the theorem based on Lagrangian quantum field theory almost half a century ago. Jost gave a more general proof based on “axiomatic” field theory nearly as long ago. The axiomatic point of view has two advantages over the Lagrangian one. First, the axiomatic point of view makes clear why is fundamental—because it is intimately related to Lorentz invariance. Secondly, the axiomatic proof gives a simple way to calculate the transform of any relativistic field without calculating , and separately and then multiplying them. The purpose of this pedagogical paper is to “deaxiomatize” the theorem by explaining it in a few simple steps. We use theorems of distribution theory and of several complex variables without proof to make the exposition elementary. 相似文献
994.
Xian Xu 《Journal of Mathematical Analysis and Applications》2006,324(1):472-490
In this paper, we study the existence and multiplicity of positive solutions for the differential equations system
995.
Joël Merker 《Acta Appl Math》2006,92(2):125-207
We treat the problem of linearizability of a system of second order ordinary differential equations. The criterion we provide has applications to nonlinear Newtonian mechanics, especially in three-dimensional space. Let or , let , let , let and let
be a collection of m analytic second order ordinary differential equations, in general nonlinear. We obtain a new and applicable necessary and sufficient condition in order that this system is equivalent, under a point transformation
to the Newtonian free particle system .Strikingly, the explicit differential system that we obtain is of first order in the case , whereas according to a classical result due to Lie, it is of second order the case of a single equation . 相似文献
996.
Stephan G. Wagner 《Acta Appl Math》2006,91(2):119-132
In this paper, we will consider the Wiener index for a class of trees that is connected to partitions of integers. Our main theorem is the fact that every integer is the Wiener index of a member of this class. As a consequence, this proves a conjecture of Lepović and Gutman. The paper also contains extremal and average results on the Wiener index of the studied class.This work was supported by Austrian Science Fund project no. S-8307-MAT. 相似文献
997.
Vadim Dubovsky Alexander Yakhot 《Numerical Methods for Partial Differential Equations》2006,22(5):1070-1079
An approximation of function u(x) as a Taylor series expansion about a point x0 at M points xi, ~ i = 1,2,…,M is used where xi are arbitrary‐spaced. This approximation is a linear system for the derivatives u(k) with an arbitrary accuracy. An analytical expression for the inverse matrix A ?1 where A = [Aik] = (xi ? x0)k is found. A finite‐difference approximation of derivatives u(k) of a given function u(x) at point x0 is derived in terms of the values u(xi). © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
998.
N. M. Gasanly 《Crystal Research and Technology》2010,45(11):1141-1144
The optical properties of TlInS2xSe2(1‐x)mixed crystals (0.25 ≤ x ≤ 1) have been studied at room temperature through the transmittance and reflectivity measurements in the wavelength range of 400–1100 nm. The spectral dependence of the refractive index for all compositions of studied crystals were obtained. The dispersion of the refractive index is discussed in terms of the Wemple–DiDomenico single‐effective‐oscillator model. The compositional dependencies of refractive index dispersion parameters: oscillator energy, dispersion energy and zero‐frequency refractive index were revealed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
999.
Consider a compact Kähler manifold endowed with a prequantum bundle. Following the geometric quantization scheme, the associated quantum spaces are the spaces of holomorphic sections of the tensor powers of the prequantum bundle. In this paper we construct an asymptotic representation of the prequantum bundle automorphism group in these quantum spaces. We estimate the characters of these representations under some transversality assumption. The formula obtained generalizes in some sense the Lefschetz fixed point formula for the automorphisms of the prequantum bundle preserving its holomorphic structure. Our results will be applied in two forthcoming papers to the quantum representation of the mapping class group. 相似文献
1000.
Zhi-Hai Zhang Kang-Xian GuoBin Chen Rui-Zhen WangMin-Wu Kang Shuai Shao 《Superlattices and Microstructures》2010
The optical absorption coefficients and the changes in the refractive index in GaAs/AlGaAs parabolic quantum dots(QDs) with applied electric and magnetic fields are studied in detail. Analytical expressions for the linear and nonlinear intersubband absorption coefficients and refractive index changes are obtained by using a compact density matrix approach and an iterative procedure. Finally, the calculated results show the incident optical intensity, the frequencies of the confined potential of the QDs and the applied electric and magnetic fields have a great influence on the optical absorption coefficients and refractive index changes in this system. 相似文献