中国财产保险公司经营效率评价及影响因素:基于CCR-BCC和Malmquist的DEA-Tobit模型北大核心

作为现代金融体系的重要组成部分,保险业的发展程度直接关系到金融业能否稳定健康发展.运用基于DEA的CCR模型、BCC模型和Malmquist指数法以及DEA-Tobit模型对2008-2011年中国36家财产保险公司经营效率及影响因素进行了实证分析,研究表明:1)从综合技术效率角度分析,达到DEA有效的保险公司数目从08年的5家上升到09年的9家,且在以后年份保持稳定数目.从静态效率均值角度分析,中国财产保险公司效率不高,各保险公司之间的差异不大.2)四年间中国财产保险公司经营效率普遍较低,然而技术进步却是提高保险公司经营效率的有效方法.3)公司经营能力与静态效率水平各分解项存在显著正相关,资本规模则与其存在显著负相关,职工素质、赔付能力及公司经营管理费用对静态效率水平各分解项影响显著性不强.     

Mutual Information of Pauli Channels with Correlated Noise

A general formula for the mutual information of the Paufi channels with memory modelled by correlated noise is derived. It is shown that the mutual information depends on the channel shrinking factor, the input state parameter and the channel memory coefficient. The analyses based on the general formula reveal that the entanglement is always a useful resource to enhance the mutual information of some Pauli channels, such as the bit flip channel and the bit-phase flip channel. Our analyses also show that the entanglement is not advantageous to the reliable transmission of classical information for some Pauli channels at any time, such as the phase flip channel and the phase damping channel.     

基于团队的知识共享和知识形成机理研究

越来越多的企业开始采用以团队为基础的组织结构，团队的核心能力在于能够实现知识共享，因此对团队知识共享及形成进行研究有着重要意义。本在阐述以团队为基础的组织与官僚层级制组织相比更有利于知识共享的基础上，从心理学和经济学的角度分析了团队知识共享的理论基础，指出了团队知识管理的三个误区，并首次提出了团队知识形成的三种机制和途径：事前学习、事中学习和外部学习。     

解读中英税收新协定

2011年6月27日,中英两国政府签署了新的关于对所得和财产收益相互避免双重征税和防止偷漏税的协定（以下简称“新协定”）。     

Deleting Vertices and Interlacing Laplacian Eigenvalues

The authors obtain an interlacing relation between the Laplacian spectra of a graph G and its subgraph G - U, which is obtained from G by deleting all the vertices in the vertex subset U together with their incident edges. Also, some applications of this interlacing property are explored and this interlacing property is extended to the edge weighted graphs.     

Influence of Oxygen Vacancy on Transport Property in Perovskite Oxide Heterostructures

Effect of oxygen vacancy on transport property of perovskite microstructures is studied theoretically. Compared with calculated and measured I-V curves, it is revealed that electron conduction plays an important role in the oxygen nonstoichiometry perovskite heterostructures even with hole-doped or un-doped material due to the oxygen vacancies. In addition, a detailed understanding of the influence of oxygen vacancy concentration and temperature on the conduction characteristics of oxide heterojunction with both forward and reverse biases is obtained by calculation.     

Synthesis and helical twisting property of polymerizable chiral dopant with temperature-dependent solubility in liquid crystal

In this study,right-handed dicinnamate isosorbide was synthesized via the esterification reaction between optically active isosorbide and cinnamate.The chiral dopant was characterized by FT-IR,~1H NMR,elemental analysis,SEM,UV absorption spectrum.After dissolving in a nematic liquid crystal mixture,the chiral dopant exhibited a temperature-dependent solubility in the chiral nematic liquid crystal mixture.Meanwhile,a relatively high value of helical twisting power of the polymerizable chiral dopant was de...     

Stable Rank One and Real Rank Zero for Crossed Products by Finite Group Actions with the Tracial Rokhlin Property

The authors prove that the crossed product of an infinite dimensional simple separable unital C＊-algebra with stable rank one by an action of a finite group with the tracial Rokhlin property has again stable rank one. It is also proved that the crossed product of an infinite dimensional simple separable unital C＊-algebra with real rank zero by an action of a finite group with the tracial Rokhlin property has again real rank zero.     

Sub-cover-avoidance Properties and the Structure of Finite Groups

A subgroup H of a group G is said to have the sub-cover-avoidance property in G ffthereis a chief series 1 = G0 ≤ G1 ≤…≤ Gn - G, such that Gi-1（H ∩ Gi） G for every i = 1,2,... ,l. In this paper, we give some characteristic conditions for a group to be solvable under the assumptions that some subgroups of a group satisfy the sub-cover-avoidance property.     

菌陈挥发油GC-MS指纹图谱分析

建立了菌陈挥发油GC-MS指纹图谱，将正交投影算法用于不同样本中共有峰的提取，提高了共有峰的识别能力，降低了由于保留时间的漂移、质谱检索匹配度不高以及色谱峰重叠而引起的共有峰识别的难度．采用共有峰率、变异率及相似度等几个指标对4个不同产地的菌陈挥发油成分进行了评价，从共性、差异和整体性等多个方面全面表征菌陈挥发油的化学模式特征．结果表明，不同产地的菌陈挥发油成分大致相同，该指纹图谱可用于菌陈中挥发油成分的质量控制．