On the discretization of nonparametric isotropic covariogram estimators

In this article, we describe the discretization of nonparametric covariogram estimators for isotropic stationary stochastic processes. The use of nonparametric estimators is important to avoid the difficulties in selecting a parametric model. The key property the isotropic covariogram must satisfy is to be positive definite and thus have the form characterized by Yaglom's representation of Bochner's theorem. We present an optimal discretization of the latter in the sense that the resulting nonparametric covariogram estimators are guaranteed to be smooth and positive definite in the continuum. This provides an answer to an issue raised by Hall, Fisher and Hoffmann (1994). Furthermore, from a practical viewpoint, our result is important because a nonlinear constrained algorithm can sometimes be avoided and the solution can be found by least squares. Some numerical results are presented for illustration.     

论会话中沉默的交际功能及文化特性

对人们日常会话中沉默所具有的交际功能及其在不同文化背景中所显示的特性进行分析,认为日常会话中的沉默并不意味着交际的失败或中断,相反它表现出多种交际功能。此外,沉默行为在不同的文化中具有不同的内涵,不同文化群体的人并不总是能很好地理解对方的沉默所蕴涵的意义。在此基础上,指出研究沉默的交际功能的目的,在于帮助交际者更好地理解会话中的言外之意及未言之意,从而使交际更加顺畅有效地进行。     

论模糊词语的语用功能

在语言交际中 ,人们运用了大量的模糊词语。模糊词语种类繁多 ,却各有特色。带有强烈的模糊特征 ,却能准确地表达和交流思想 ;能使语言表达更生动 ,更形象 ,更含蓄 ,更委婉 ;增强语言表达的灵活性。     

Efficient Estimation of Fixed and Time-varying Covariate Effects in Multiplicative Intensity Models

The proportional hazards assumption of the Cox model does sometimes not hold in practise. An example is a treatment effect that decreases with time. We study a general multiplicative intensity model allowing the influence of each covariate to vary non-parametrically with time. An efficient estimation procedure for the cumulative parameter functions is developed. Its properties are studied using the martingale structure of the problem. Furthermore, we introduce a partly parametric version of the general non-parametric model in which the influence of some of the covariates varies with time while the effects of the remaining covariates are constant. This semiparametric model has not been studied in detail before. An efficient procedure for estimating the parametric as well as the non-parametric components of this model is developed. Again the martingale structure of the model allows us to describe the asymptotic properties of the suggested estimators. The approach is applied to two different data sets, and a Monte Carlo simulation is presented.     

Dispersive ordering—Some applications and examples

A basic concept for comparing spread among probability distributions is that of dispersive ordering. Let X and Y be two random variables with distribution functions F and G, respectively. Let F ⁻¹ and G ⁻¹ be their right continuous inverses (quantile functions). We say that Y is less dispersed than X (Y≤ _disp X) if G ⁻¹(β)−G ⁻¹(α)≤F ⁻¹(β)−F ⁻¹(α), for all 0<α≤β<1. This means that the difference between any two quantiles of G is smaller than the difference between the corresponding quantiles of F. A consequence of Y≤ _disp X is that |Y ₁−Y ₂| is stochastically smaller than |X ₁−X ₂| and this in turn implies var(Y)≤var(X) as well as E[|Y ₁−Y ₂|]≤E[|X ₁−X ₂|], where X ₁, X ₂ (Y ₁, Y ₂) are two independent copies of X(Y). In this review paper, we give several examples and applications of dispersive ordering in statistics. Examples include those related to order statistics, spacings, convolution of non-identically distributed random variables and epoch times of non-homogeneous Poisson processes. This work was supported in part by KOSEF through Statistical Research Center for Complex Systems at Seoul National University. Subhash Kochar is thankful to Dr. B. Khaledi for many helpful discussions.     

企业工会和企业党组织的功能融合——探索一种适应市场经济发展的新的改革模式

企业党组织和企业经营管理机构的一体化运作模式,在创建中国现代化工业体系的发展过程中发挥了巨大作用。但在日趋激烈的市场竞争之下,这种一体化运作模式已经越来越难以适应市场经济发展的要求了。把企业党组织和企业工会的功能融合起来,探索一条具有制度创新意义的改革之路,应是一个大胆的创新。     

对标记性句首成分的话语功能的考察

文章从语篇和语用方面,考察英语陈述句的标记性句首成分的话语功能。影响标记性的句首成分的话语功能的常量包括语篇语用常量,这里话语功能视为增加到正常词序的句子的命题内容中的额外意义成分和这样的词序变化对句子所在语境的贡献,以此识别两类基本话语功能,即达到突显性和得到强调的语用功能;将上下文连接起来并重新安排句中成分的语篇功能。     

科技英语语篇中的词汇同现

从国内外对衔接及词汇衔接的研究入手,立足于有关词汇同现关系研究的理论成果,在真实的土木工程英语语篇中分析词汇同现的手段和功能,从而揭示出科技英语语篇中词汇同现的特点:(1)在科技英语语篇中,同一序列关系常常出现在有关设计、施工程序类的篇章中;(2)非序列词汇套在关于机械、设备、仪器的使用或说明的科技英语语篇中体现得十分突出;(3)预期关系存在于专业性很强的篇章中,并且在这种关系中的词项虽然倾向于出现在同一语境中,但它们在语义上不一定有系统联系。     

非正式称呼的交际功能

就北京地区国家部委机关公务员非正式场合使用的称呼形式,在问卷调查、实地观察以及个人访谈的基础上,从社会语言学的角度进一步加以阐述。非正式称呼是一种特殊的称谓,它排除共性,强调个性,突出称呼者与被称呼者之间一种共有的和谐的特殊关系,有利于消除正式场合使用正式称呼时所要求的权利尊严、上下秩序、形式规则诸因素附加给称呼者的种种紧张与不利因素。公务员在交往中使用非正式称呼的功能具有多样性,它为不同群体提供了广泛多向的交流空间,其社会交际功能值得研究。     

县乡财政解困的路径探索

现阶段我国地方财政存在着严重的问题,突出表现在县乡两级财政日益陷入困境。造成县乡财政困难的原因当然是多方面的,但最根本的原因还是制度因素。因此,不能就财政论财政,而应该从问题的根源入手,从县乡财政解困所必须的基本前提入手,来探讨根本的解决之道。