心律波动信号的1/f噪声特性分析

心律波动信号具有1/f噪声特性,是非平稳的。该文采用平均功率谱密度方法,分析了基于平均功率谱密度和最小二乘拟合法求正常人和心脏充血患者的心律波动信号的谱参数,发现根据谱参数可以定量地区分正常人与心脏充血患者:大部分正常人的心律波动信号的谱参数大于1,而大部分心脏充血患者的心律波动信号的谱参数小于1,该结论可为心脏病的诊断与预诊断提供一种辅助手段。     

Issues in applying recent CPMP ‘Points to Consider’ and FDA guidance documents with biostatistical implications

The International Conference on Harmonisation guideline ‘Statistical Principles for Clinical Trials’ was adopted by the Committee for Proprietary Medicinal Products (CPMP) in March 1998, and consequently is operational in Europe. Since then more detailed guidance on selected topics has been issued by the CPMP in the form of ‘Points to Consider’ documents. The intent of these was to give guidance particularly to non‐statistical reviewers within regulatory authorities, although of course they also provide a good source of information for pharmaceutical industry statisticians. In addition, the Food and Drug Administration has recently issued a draft guideline on data monitoring committees. In November 2002 a one‐day discussion forum was held in London by Statisticians in the Pharmaceutical Industry (PSI). The aim of the meeting was to discuss how statisticians were responding to some of the issues covered in these new guidelines, and to document consensus views where they existed. The forum was attended by industry, academic and regulatory statisticians. This paper outlines the questions raised, resulting discussions and consensus views reached. It is clear from the guidelines and discussions at the workshop that the statistical analysis strategy must be planned during the design phase of a clinical trial and carefully documented. Once the study is complete the analysis strategy should be thoughtfully executed and the findings reported. Copyright © 2003 John Wiley & Sons, Ltd.     

Optimal scaling of Metropolis algorithms: Heading toward general target distributions

The authors provide an overview of optimal scaling results for the Metropolis algorithm with Gaussian proposal distribution. They address in more depth the case of high‐dimensional target distributions formed of independent, but not identically distributed components. They attempt to give an intuitive explanation as to why the well‐known optimal acceptance rate of 0.234 is not always suitable. They show how to find the asymptotically optimal acceptance rate when needed, and they explain why it is sometimes necessary to turn to inhomogeneous proposal distributions. Their results are illustrated with a simple example.     

A bayesian estimator for the dependence function of a bivariate extreme‐value distribution

Any continuous bivariate distribution can be expressed in terms of its margins and a unique copula. In the case of extreme‐value distributions, the copula is characterized by a dependence function while each margin depends on three parameters. The authors propose a Bayesian approach for the simultaneous estimation of the dependence function and the parameters defining the margins. They describe a nonparametric model for the dependence function and a reversible jump Markov chain Monte Carlo algorithm for the computation of the Bayesian estimator. They show through simulations that their estimator has a smaller mean integrated squared error than classical nonparametric estimators, especially in small samples. They illustrate their approach on a hydrological data set.     

一种LOG-MAP算法的改进迭代实现及其结构

对LOG-MAP算法进行了可并发性分析,利用可以完整接收一个N长符号传输帧的条件以及正向迭代和反向迭代中的固有对称性质,提出了LOG-MAP算法的一种修正迭代实现算法,其正向和反向迭代计算次数只需码长N的一半,故比标准LOG-MAP算法提高了一倍的处理速度,且没有空间开销的增加、同时,根据修正的迭代实现算法给出了相应的适于FPGA实现的双总线硬件结构的实现方案。     

煤炭城市发展非煤产业研究

煤炭城市产业结构生成和变化的特殊性 ,决定其发展非煤产业具有历史必然性和现实紧迫性。煤炭城市发展非煤产业应选择以煤炭等矿产品的深加工转化型为主 ,以节能综合利用型为辅 ,相关产业配套 ,非相关产业适当发展的模式。模式的实施和实现 ,要依靠国家调整宏观调控政策 ,健康发展煤炭主业 ;要建立煤矿转产基金 ,为非煤产业提供必要的积累 ;要调整投资结构 ,搞好招商引资 ;要制定科技进步政策 ,增强科技创新能力 ;要加强生态环境保护与建设 ,提高可持续发展能力 ;要深化煤炭企业改革 ,加快体制和机制创新 ;要实施人才战略 ,用新机制上新项目     

以太网光桥的研究

根据有关网络技术和具体的实验,提出一种以太网光桥的实现方案,并对光桥的几个性能参数进行了分析讨论。     

发生认识论的哲学来源

皮亚杰的发生认识论并不是一个纯粹的发展心理学理论,而是一个关于认知的结构及其发生与发展的理论。发生认识论的建立有其深厚的哲学根源:它是在批判传统认识论中的经验主义和理性主义的基础上建立起来的。皮亚杰看到,无论是经验主义方法,还是理性主义方法对于认知的结构及其发生与发展的解释都是片面的,因为前者忽视了结构,后者假设了结构而没有注意到结构发展的自然进程。皮亚杰在对两者辨证综合的基础上,提出“发生学的结构主义”,指出认识的发生与发展是因为我们作为生物先天地就包含着这样的结构,而且是因为我们作为生物对结构进行主动建构的结果。     

Domains of convergence for the EM algorithm: a cautionary tale in a location estimation problem

The EM algorithm is a popular method for maximizing a likelihood in the presence of incomplete data. When the likelihood has multiple local maxima, the parameter space can be partitioned into domains of convergence, one for each local maximum. In this paper we investigate these domains for the location family generated by the t-distribution. We show that, perhaps somewhat surprisingly, these domains need not be connected sets. As an extreme case we give an example of a domain which consists of an infinite union of disjoint open intervals. Thus the convergence behaviour of the EM algorithm can be quite sensitive to the starting point.