自旋电子在钙钛矿锰氧化物中输运性质研究

本文对国内外研究钙钛矿锰氧化物磁电性质及CMR效应的现状进行了分析,指出有必要研究自旋电子在钙铁矿锰氧化物中的输运性质与材料的磁性以及外加磁场的关系,并对研究方法进行了探讨。     

蜘蛛丝的结构与力学性能

本文主要介绍了蜘蛛丝的形成和力学性能特征，分析了其结构与力学性能间的关系。     

对《文物保护法》有关民间收藏文物诸条款的若干思考

2002年10月28日颁布实施的《文物保护法》将原法“私人收藏文物”更名为“民间收藏文物”，并由原来的3条增加到10条。新《文物保护法》对民间收藏文物诸条款的规定，一方面能够适应社会主义市场经济体制建立后所面临的新情况，另一方面在管理制度和政策上有利于实行适度开放的政策，从而达到规范市场，使民间收藏文物有序流通的目的。     

Simultaneous sparse model selection and coefficient estimation for heavy-tailed autoregressive processes

We propose a sparse coefficient estimation and automated model selection procedure for autoregressive processes with heavy-tailed innovations based on penalized conditional maximum likelihood. Under mild moment conditions on the innovation processes, the penalized conditional maximum likelihood estimator satisfies a strong consistency, O_P(N^?1/2) consistency, and the oracle properties, where N is the sample size. We have the freedom in choosing penalty functions based on the weak conditions on them. Two penalty functions, least absolute shrinkage and selection operator and smoothly clipped average deviation, are compared. The proposed method provides a distribution-based penalized inference to AR models, which is especially useful when the other estimation methods fail or under perform for AR processes with heavy-tailed innovations [Feigin, Resnick. Pitfalls of fitting autoregressive models for heavy-tailed time series. Extremes. 1999;1:391–422]. A simulation study confirms our theoretical results. At the end, we apply our method to a historical price data of the US Industrial Production Index for consumer goods, and obtain very promising results.     

Stochastic properties of the mixed accelerated hazard models

The accelerated hazard model in survival analysis assumes that the covariate effect acts the time scale of the baseline hazard rate. In this paper, we study the stochastic properties of the mixed accelerated hazard model since the covariate is considered basically unobservable. We build dependence structure between the population variable and the covariate, and also present some preservation properties. Using some well-known stochastic orders, we compare two mixed accelerated hazards models arising out of different choices of distributions for unobservable covariates or different baseline hazard rate functions.     

A note on nonlinear regression for the autoregressive moving average with non-hd errors

Estimation by nonlinear regression of the parameters for the stationary and invertible autoregressive moving average (ARMA) model with mixing or martingale difference errors is considered. Simple proofs of consistency and asymptotic normality for the nonlinear least squares estimator are given by exploiting results from nonlinear estimation theory and mixing and mixingale theory.     

Bivariate log Birnbaum–Saunders distribution

Univariate Birnbaum–Saunders distribution has received a considerable amount of attention in recent years. Rieck and Nedelman (A log-linear model for the Birnbaum–Saunders distribution. Technometrics, 1991;33:51–60) introduced a log Birnbaum–Saunders distribution. The main aim of this paper is to introduce bivariate log Birnbaum–Saunders distribution. The proposed model is symmetric and it has five parameters. It can be obtained using Gaussian copula. Different properties can be obtained using copula structure. It is observed that the maximum likelihood estimators (MLEs) cannot be obtained explicitly. Two-dimensional profile likelihood approach may be adopted to compute the MLEs. We propose some alternative estimators also, which can be obtained quite conveniently. The analysis of one data set is performed for illustrative purposes. Finally, it is observed that this model can be used as a bivariate log-linear model, and its multivariate generalization is also quite straight forward.     

学前儿童基于重量和声音进行因果推理的发展研究

儿童的推理能力历来都是考察儿童认知发展的重点。本研究探讨了在多种属性刺激下3~5岁儿童基于重量和声音进行 因果推理的表现。结果发现：4岁和5岁儿童选择正确目标物的准确率显著高于3岁儿童；和同时使用声音与重量判断目标物相 比，儿童在单独使用重量或声音的情况下更容易区分目标物。总之，儿童因果推理能力发展的关键期在4岁并且当任务难度较高 的情况下其因果机制极易受到干扰。     

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.     

日语听力教学刍议

培养听解能力 ,首先要把握听的对象 ,其次是听解过程的各种关键要素。除此之外 ,还要考虑听力为什么难、难在何处 ,并在全面了解听力的特性、特点和形式的基础上 ,进行适当的指导