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.     

Some properties of tests for parameters that can be arbitrarily close to being unidentified

Confidence intervals for parameters that can be arbitrarily close to being unidentified are unbounded with positive probability [e.g. Dufour, J.-M., 1997. Some impossibility theorems in econometrics with applications to instrumental variables and dynamic models. Econometrica 65, 1365–1388; Pfanzagl, J. 1998. The nonexistence of confidence sets for discontinuous functionals. Journal of Statistical Planning and Inference 75, 9–20], and the asymptotic risks of their estimators are unbounded [Pötscher, B.M., 2002. Lower risk bounds and properties of confidence sets for ill-posed estimation problems with applications to spectral density and persistence estimation, unit roots, and estimation of long memory parameters. Econometrica 70, 1035–1065]. We extend these “impossibility results” and show that all tests of size α concerning parameters that can be arbitrarily close to being unidentified have power that can be as small as α for any sample size even if the null and the alternative hypotheses are not adjacent. The results are proved for a very general framework that contains commonly used models.     

On the incidence–prevalence relation and length‐biased sampling

For many diseases, logistic constraints render large incidence studies difficult to carry out. This becomes a drawback, particularly when a new study is needed each time the incidence rate is investigated in a new population. By carrying out a prevalent cohort study with follow‐up it is possible to estimate the incidence rate if it is constant. The authors derive the maximum likelihood estimator (MLE) of the overall incidence rate, λ, as well as age‐specific incidence rates, by exploiting the epidemiologic relationship, (prevalence odds) = (incidence rate) × (mean duration) (P/[1 ? P] = λ × µ). The authors establish the asymptotic distributions of the MLEs and provide approximate confidence intervals for the parameters. Moreover, the MLE of λ is asymptotically most efficient and is the natural estimator obtained by substituting the marginal maximum likelihood estimators for P and µ into P/[1 ? P] = λ × µ. Following‐up the subjects allows the authors to develop these widely applicable procedures. The authors apply their methods to data collected as part of the Canadian Study of Health and Ageing to estimate the incidence rate of dementia amongst elderly Canadians. The Canadian Journal of Statistics © 2009 Statistical Society of Canada     

Nonparametric estimation of the shape function in a Gamma process for degradation data

The author considers estimation under a Gamma process model for degradation data. The setting for degradation data is one in which n independent units, each with a Gamma process with a common shape function and scale parameter, are observed at several possibly different times. Covariates can be incorporated into the model by taking the scale parameter as a function of the covariates. The author proposes using the maximum pseudo‐likelihood method to estimate the unknown parameters. The method requires usage of the Pool Adjacent Violators Algorithm. Asymptotic properties, including consistency, convergence rate and asymptotic distribution, are established. Simulation studies are conducted to validate the method and its application is illustrated by using bridge beams data and carbon‐film resistors data. The Canadian Journal of Statistics 37: 102‐118; 2009 © 2009 Statistical Society of Canada     

Normal approximation to the hypergeometric distribution in nonstandard cases and a sub-Gaussian Berry–Esseen theorem

In this paper, we consider simple random sampling without replacement from a dichotomous finite population. We investigate accuracy of the Normal approximation to the Hypergeometric probabilities for a wide range of parameter values, including the nonstandard cases where the sampling fraction tends to one and where the proportion of the objects of interest in the population tends to the boundary values, zero and one. We establish a non-uniform Berry–Esseen theorem for the Hypergeometric distribution which shows that in the nonstandard cases, the rate of Normal approximation to the Hypergeometric distribution can be considerably slower than the rate of Normal approximation to the Binomial distribution. We also report results from a moderately large numerical study and provide some guidelines for using the Normal approximation to the Hypergeometric distribution in finite samples.     

Approximation of the distribution of excesses through a generalized probability-weighted moments method

The POT (peaks-over-threshold) approach consists in using the generalized Pareto distribution (GPD) to approximate the distribution of excesses over a threshold. In this paper, we consider this approximation using a generalized probability-weighted moments (GPWM) method. We study the asymptotic behaviour of our new estimators and also the functional bias of the GPD as an estimate of the distribution function of the excesses. A simulation study is provided in order to appreciate the efficiency of our approach.     

新闻访谈第三话轮中主持人评价的缺失

会话的基本单位是由三个话轮构成的序列结构,它普遍存在于日常会话和机构会话中。分析和归纳新闻访谈中第三话轮的结构特征和语用功能发现,新闻访谈中第三话轮是节目主持人进行语言选择的结果。尽管第三话轮内容有一定的变化,但是评价不会出现在第三话轮中,这个特点是主持人顺应机构特征和机构规定的结果。     

由MP3版权纠纷看网络著作权利益之平衡

互联网的蓬勃发展对传统版权制度提出新的挑战。现实世界的版权保护适用到虚拟世界里会显失公平。本文以MP3版权纠纷为例，分析如何平衡版权人与社会公众间的利益冲突，促使法律更好地为科技的发展服务。     

论高师院校数学课程“3+1”培养模式

为适应未来基础教育的发展趋势,适应社会主义市场经济对人才的要求,培养出“重基础、宽口径、强能力、高素质”的数学人才,高师院校数学课程必须进行改革,而“3+1”培养模式的构建实施通过实践检验,是非常有效的一种教学方式。具体来说:“3+1”模式就是把大学四年分成两个阶段,“3”就是大学前三年主要学习数学的基础课、专业基础课及公共课,主要是打好基础。“1”就是大学第四年主要学习应用性、实践性和技能课等,加大学生的实习和实践内容,以提高学生的动手、操作、实践、应用能力,提高毕业生的就业适应能力和竞争能力。其指导思想就是“三个面向”———面向基础、面向世界、面向21世纪和“重组基础、拓宽口径、综合交叉、提高素质”,以及依托师范、突出学术、强化技能、增强应用。     

实施用科研加快建设合格本科院校的战略举措

根据从专科转向建设本科院校的实践,本文首先讨论了科研在高校中的作用,接着阐述了科研工作的层次性特点,然后简述了用科研手段来加快由专科向本科转变步伐的可行性,最后就如何实施此项战略举措开展了较深入的探讨。所以,本文可能对于丰富在专科基础上快速建设合格本科院校的理论与实践具有意义。