Extensible hyperplane nets

Extensible (polynomial) lattice point sets have the property that the number N of points in the node set of a quasi-Monte Carlo algorithm may be increased while retaining the existing points. Explicit constructions for extensible (polynomial) lattice point sets have been presented recently by Niederreiter and Pillichshammer. It is the aim of this paper to establish extensibility for a powerful generalization of polynomial lattice point sets, the so-called hyperplane nets.     

158A GeV/c Pb+Pb碰撞可能有QGP的一旁证

用不含QGP假设的强子和弦级联模型(JPCIAE) ,研究了CERNWA98实验组新近发表的158 AGeV/c Pb+Pb中心碰撞中直接光子和π⁰粒子的横动量分布:两者的理论结果均一致的低于实验值.联系到JPCIAE能成功解释无直接光子超出确切迹象的WA80和WA93对200A GeV/c S+Au中心碰撞测量得出的结果:因而为158A GeV/c Pb+Pb中心碰撞中可能有QGP生成提供了一个旁证.     

A Pathway of Synthesis Toward the Aspidosperma Alkaloids

A recent synthesis of a vincadifformine (1) derivative followed a c-b-a order of bond construction,² which postpones the introduction of the angular ethyl group until a late stage of the reaction sequence. In view of the new, ready access to compounds^3,4 whose structures represent nearly the full complement of carbons characteristic of the non-tryptamine portion of the Aspidosperma alkaloids their use in the total synthesis of such natural bases could be envisaged. The present communication illustrates a c-b-a approach to Aspidosperma alkaloid synthesis by exploitation of the pyran derivative 2 and hence by early introduction of the angular ethyl group.⁵     

Coupling of mixed finite elements and boundary elements

The symmetric coupling of mixed finite element and boundaryelement methods is analysed for a model interface problem withthe Laplacian. The coupling involves a further continuous ansatzfunction on the interface to link the discontinuous displacementfield to the necessarily continuous boundary ansatz function.Quasi-optimal a priori error estimates and sharp a posteriorierror estimates are established which justify adaptive mesh-refiningalgorithms. Numerical experiments prove the adaptive couplingas an efficient tool for the numerical treatment of transmissionproblems.     

Korobov Spaces with Respect to Digital Orthonormal Bases

 For an orthonormal basis (ONB) of we define classes of functions according to the order of decay of the Fourier coefficients with respect to the considered ONB . The rate is expressed in the real parameter α. We investigate the following problem: What is the order of decay, if any, when we consider with respect to another ONB ? If the function is expressable as an absolutely convergent Fourier series with respect to , we give bounds for the new order of decay, which we call . Special attention is given to digital orthonormal bases (dONBs) of which the Walsh and Haar systems are examples treated in the present paper. Bounding intervals and in several cases explicit values for are given for the case of dONBs. An application to quasi-Monte Carlo numerical integration is mentioned. (Received 21 February 2000; in revised form 19 October 2000)     

A general analytic procedure for calculating two-centre integrals involving the one-electron dipolar coupling operator and Slater atomic orbitals

Analytic expressions are derived for the hybrid-type two-centre matrix elements of the one-electron dipolar coupling operator between Slater atomic orbitals. The method used is of wide applicability. The matrix elements of interest are written in terms of a generalized form of overlap integral. The overlap integrals are evaluated using the convolution theorem/contour integration technique. Computational results are discussed and times given.     

Examples of Bosonic de Finetti States over Finite Dimensional Hilbert Spaces

According to the Quantum de Finetti Theorem, locally normal infinite particle states with Bose–Einstein symmetry can be represented as mixtures of infinite tensor powers of vector states. This note presents examples of infinite-particle states with Bose–Einstein symmetry that arise as limits of Gibbs ensembles on finite dimensional spaces, and displays their de Finetti representations. We consider Gibbs ensembles for systems of bosons in a finite dimensional setting and discover limits as the number of particles tends to infinity, provided the temperature is scaled in proportion to particle number