Ambient connections realising conformal Tractor holonomy

For a conformal manifold we introduce the notion of an ambient connection, an affine connection on an ambient manifold of the conformal manifold, possibly with torsion, and with conditions relating it to the conformal structure. The purpose of this construction is to realise the normal conformal Tractor holonomy as affine holonomy of such a connection. We give an example of an ambient connection for which this is the case, and which is torsion free if we start the construction with a C-space, and in addition Ricci-flat if we start with an Einstein manifold. Thus, for a C-space this example leads to an ambient metric in the weaker sense of Čap and Gover, and for an Einstein space to a Ricci-flat ambient metric in the sense of Fefferman and Graham. Current address for first author: Erwin Schr?dinger International Institute for Mathematical Physics (ESI), Boltzmanngasse 9, 1090 Vienna, Austria Current address for second author: Department of Mathematics, University of Hamburg, Bundesstra?e 55, 20146 Hamburg, Germany     

Runge–Kutta convolution quadrature methods for well-posed equations with memory

Runge–Kutta based convolution quadrature methods for abstract, well-posed, linear, and homogeneous Volterra equations, non necessarily of sectorial type, are developed. A general representation of the numerical solution in terms of the continuous one is given. The error and stability analysis is based on this representation, which, for the particular case of the backward Euler method, also shows that the numerical solution inherits some interesting qualitative properties, such as positivity, of the exact solution. Numerical illustrations are provided.     

热传导型半导体瞬态问题特征变网格有限元法及其分析

热传导型半导体器件的瞬时状态由四个方程的非线性偏微分方程组的初边值问题所决定，其中电子位势方程是椭圆型的，电子和空穴浓度方程是对流扩散型的，温度方程为热传导型的。本文提出解这类问题的特征变网格有限元法，并进行了理论分析，在一定条件下，得到了某种意义下的最佳L^2误差估计结果。     

Slutsky定理在样本分位数的极限分布证明上的应用

为了更好地理解和应用样本分位数的极限分布,利用Slutsky定理,推导了样本分位数的极限分布.     

The tangential end fibration of an aspherical Poincaré complex

We construct a sphere fibration over a finite aspherical Poincaré complex X, which we call the tangential end fibration, under the condition that the universal cover of X is forward tame and simply connected at infinity. We show that it is tangent to X if the formal dimension of X is even or, when the formal dimension is odd, if the diagonal X→X×X admits a Poincaré embedding structure.     

Lagrangian skeletons,periodic geodesic flows and symplectic cuttings

In this paper, we investigate symplectic manifolds endowed with a Morse–Bott function with only two critical submanifolds, one of which is Lagrangian while the other one is symplectic.     

Primes in quadratic progressions on average

In this paper, we establish a theorem on the distribution of primes in quadratic progressions on average.     

陆地棉体细胞胚胎的发生和遗传转化条件初探

以陆地棉（冀棉20）下胚轴为外植体，在含KT0．3mg／L和2，4－D0．08mg／L的MS培养基上，诱导产生了胚性愈伤组织，继代培养不需要添加激素，胚性愈伤组织即分化为胚状体，并萌发出小芽，胚状体萌发过程与合子胚相似，但出现了一些畸形胚，解剖学方法观察发现，这些畸形胚的维管束系统不明显或形态异常，以农杆菌介导法对冀棉20胚状体及胚性愈伤组织进行了雪花莲凝集素（GNA）基因的遗传转化条件探索，并以GUS基域瞬间进行检测加以证实，得出农杆菌的浓度为O．D600＝0．8时，浸染时间为5min，共培养时间为3d，筛选培养基中卡那霉素浓度为75mg／L，对冀棉20胚状体及胚性愈伤组织转化是较为适合的。     

A supraconvergent scheme for the Korteweg-de Vries equation

Summary A finite-difference method for the integration of the Korteweg-de Vries equation on irregular grids is analyzed. Under periodic boundary conditions, the method is shown to be supraconvergent in the sense that, though being inconsistent, it is second order convergent. However, such a convergence only takes place on grids with an odd number of points per period. When a grid with an even number of points is used, the inconsistency of the method leads to divergence. Numerical results backing the analysis are presented.     

The σ<Emphasis Type="Italic">g</Emphasis>-Drazin Inverse and the Generalized Mbekhta Decomposition

In this paper we define and study an extension of the g-Drazin for elements of a Banach algebra and for bounded linear operators based on an isolated spectral set rather than on an isolated spectral point. We investigate salient properties of the new inverse and its continuity, and illustrate its usefulness with an application to differential equations. Generalized Mbekhta subspaces are introduced and the corresponding extended Mbekhta decomposition gives a characterization of circularly isolated spectral sets.