Divisor class group and canonical class of rings defined by ideals of pfaffians

In this paper we study the rings defined by ideals of pfaffians of a skew symmetric matrix of indeterminates. We analyze the case in which the pfaffians are not necessarily of fixed size. We prove that such rings are Cohen-Macaulay normal domains and we compute the divisor class group and the canonical class. It allows us to determine which of our rings are Gorenstein.     

Invariant bilinear forms on real irreducible representations of real semisimple lie algebras *

In this note, we give a necessary and sufficient condition for a real irreducible representation of a real simple Lie algebra to admit an invariant bilinear form. We also determine when the invariant bilinear form is symmetric or skew-symmetric.     

Twisted shear Alfvén waves with orbital angular momentum

It is shown that a dispersive shear Alfvén wave (DSAW) in a magnetized plasma can propagate as a twisted Alfvén vortex beam carrying orbital angular momentum (OAM). We obtain a wave equation from the generalized ion vorticity equation and the magnetic field-aligned electron momentum equation that couple the scalar and vector potentials of the DSAW. A twisted shear Alfvén vortex beam can trap and transport plasma particles and energy in magnetoplasmas, such as those in the Earth?s auroral zone, in the solar atmosphere, and in Large Plasma Device (LAPD) at University of California, Los Angeles.     

Second Leibniz cohomology group of twisted N = 2 superconformal algebra

In this paper, we obtain all the Leibniz 2-cocycles of the twisted N = 2 superconformal algebra ℒ, which determine its second Leibniz cohomology group.     

TAGSM光束在大气湍流中传输

基于广义惠更斯－菲涅耳原理,利用部分相干光复曲率张量研究了有扭曲的各向异性高斯－谢尔模型光束在湍流大气中的传输规律.根据有扭曲的各向导性高斯-谢尔模型光束在大气湍流中传播距离z处的部分相干复曲率张量给出了光束参量的表达式和详细的数值计算结果.结果表明：大气湍流减缓了光束扭曲参量随传播距离的衰减趋势,增大了主方向上的波前曲率的峰值,而且大气湍流退化了光束的相干性,使得光束扩展严重;光源扭曲参量大小和相干性也都会影响TAGSM光束在大气湍流中传输时各个光束参量的变化规律.     

A boundedness result for twisted convolution

We consider twisted convolution operators with kernels having singularities on a sphere and having as Fourier transform the oscillatory symbol m_α(|ξ|) = |ξ|^–αe^i|ξ|, 0 ≤ ??α < 2n. We give integral representations for such operators and, as a principal result, we study L_p–L_q estimates for them.     

Interface formation and a structural phase transition for the spherical model of ferromagnetism

A detailed analysis is reported examining the local magnetic susceptibility (r), in relation to the correlation functionG(R) and correlation length , of a spherical model ferromagnet confined to geometry =L ^{d –d} × ^d ( ^d 2,d>2) under a continuous set oftwisted boundary conditions. The twist parameter in this problem may be interpreted as a measure of the geometry-dependent doping level of interfacial impurities (or antiferromagnetic seams) in theextended system at various temperatures. For _j 0, jd-d, no seams are present except at infinity, whereas if _j = 1/2, impurity saturation occurs. For 0 < _j < 1/2 the physical domain _phys =D ^{d –d} × ^d (D>L), defining the region between seams containing the origin, depends on temperature above a certain threshold (T>T ₀). Below that temperature (T>T ₀), seams are frozen at the same position (DL/2,d-d'=1), revealing a smoothly varying largescale structural phase transition.     

非平面扭曲构象对1，3－二苯基吡唑啉衍生物荧光性质的影响

研究了１，３－二苯基吡唑啉（ＤＰＰ）和１－苯基－３－（４－硝基苯基）吡唑啉（ＰＮＰ）在室温及７７Ｋ时不同溶剂中的荧光光谱，发现在非极性溶剂中７７Ｋ时ＤＰＰ的荧光强度远比其在室温时的低，而ＰＮＰ则完全没有荧光，表明这些化合物激发态的构象松驰，形成非平面扭曲构象对分子的发光性质十分重要。同时发现这两个化合物具有不同的关键性扭曲部位，形成各自有利于发光的构象，Ｎ－１上及Ｃ－３上苯环的扭曲分别对ＤＰＰ和ＰＮＰ的发光态的形成起着重要作用。