Measures of dependence for the multivariate t distribution with applications to the stock market

Two measures of dependence for multivariate t and Cauchy random variables are developed based on Kullback–Leibler number. The mutual information number T(X) is obtained in a closed expression form, as well as its asymptotic distribution. A dependence coefficient ρ₁, is defined (based on the Kullback–Leibler number) with the properties of ρ₁=0 indicating independence and ρ₁=1indicating degeneracy. Two real life examples from the stock market are used to analyze the level of dependence and correlation among stocks.     

阴离子表面活性剂的应用及发展

阴离子表面活性剂是表面活性剂家庭中的一大类。文中重点介绍了阴离子表面活性剂在农业、建筑业、石油、化妆品及纺织业中的应用，展望了发展前景。     

Estimation of Location Parameters Under Nonnormal Errors and Quadratic Loss

Assuming a statistical model in which the joint distribution of the unobservable errors is drawn from independent univariate Student t's that are identically and symmetrically distributed, the sampling performance of traditional robust estimators and a family of Stein-like estimators are compared and evaluated. These results suggest that under thick-tailed distributions, the relative sampling performances and risk characteristics for a range of nonconventional Stein estimators remains approximately the same as in the case of their normal counterparts. The empirical risk implications of misspecifying the error distribution are investigated.     

Robust test for means when population variances are unequal

We consider the problem of testing the equality of two population means when the population variances are not necessarily equal. We propose a Welch-type statistic, say T^* _c, based on Tiku!s ‘1967, 1980’ modified maximum likelihood estimators, and show that this statistic is robust to symmetric and moderately skew distributions. We investigate the power properties of the statistic T^* _c; T^* _c clearly seems to be more powerful than Yuen's ‘1974’ Welch-type robust statistic based on the trimmed sample means and the matching sample variances. We show that the analogous statistics based on the ‘adaptive’ robust estimators give misleading Type I errors. We generalize the results to testing linear contrasts among k population means     

SrBPO5:Ce3 的光谱特性

运用高温固相法,在空气中合成了SrBPO5:Ce3 荧光体,通过研究SrBPO5:Ce3 的光谱特性,发现激发光谱随Ce3 的掺入量增加而红移,据此认为Ce3 在进入格位时有两种电荷补偿方式,发射光谱则随Ce3 的掺入量增加而增强.     

全面建设小康社会与西部多元文化

全面建设小康社会是实现中华民族伟大复兴的伟大工程。全面建设小康社会 ,加快多民族聚居的西部地区的发展至为关键。而维护和发展西部多元文化对实施西部大开发战略 ,全面建设小康社会具有十分重要意义     

锂离子二次电池正极材料尖晶石型LiMn_2O_4的研究进展

近年来,锂离子电池因其优异的特性,发展十分迅速。锂离子电池的优异性能与电池的材料选择,材料的制备工艺等密切相关。正极材料LiMn2O4是近几年锂离子电池研究的热点,但其在循环过程中的容量衰减是制约锂离子电池商品化的关键。本文介绍了不同正极材料的结构、电化学性能、研究现状,侧重于阐述控制锂离子电池循环过程中可逆嵌锂容量和稳定性的嵌锂电极材料的结构性质。     

Best monotone M‐estimators

The author shows how to find M‐estimators of location whose generating function is monotone and which are optimal or close to optimal. It is easy to identify a consistent sequence of estimators in this class. In addition, it contains simple and efficient approximations in cases where the likelihood function is difficult to obtain. In some neighbourhoods of the normal distribution, the loss of efficiency due to the approximation is quite small. Optimal monotone M‐estimators can also be determined in cases when the underlying distribution is known only up to a certain neighbourhood. The author considers the e‐contamination model and an extension thereof that allows the distributions to be arbitrary outside compact intervals. His results also have implications for distributions with monotone score functions. The author illustrates his methodology using Student and stable distributions.     

含硫氮氧的螯合树脂的合成及吸附性能

本工作用Ｎ，Ｎ－二乙氨基环氧丙烷和Ｎ，Ｎ－二乙氨基环硫丙烷分别与含仲氨基的高分子载体进行反应，合成得到两类分别含羟基和巯基的叔胺型螯合树脂；用静态法测定了树脂对Ａｕ（Ⅲ），Ｐｄ（Ⅱ），Ｐｔ（Ⅳ），Ａｇ（Ⅰ），Ｈｇ（Ⅱ），Ｃｕ（Ⅱ），Ｚｎ（Ⅱ）的吸附特性，结果发现树脂对于贵金属离子有较好的吸附性能。     

社会浮躁现象发生的原因及其遏制对策

从文化冲击、人性趋向、认知偏差、个人主义化与安全方面分析社会浮躁成因。本文认为,应从重新定位政府职能、以未来作为思考基点增强变革能力、抑制人性不良趋向加强舆论监督、矫正偏差等方面预防和遏制浮躁,使社会稳定发展。