Estimating the Cluster Tree of a Density by Analyzing the Minimal Spanning Tree of a Sample

runt pruning , a new clustering method that attempts to find modes of a density by analyzing the minimal spanning tree of a sample. The method exploits the connection between the minimal spanning tree and nearest neighbor density (e.g. normal mixture) or about the geometric shapes of the clusters, and is computationally feasible for large data sets.     

乔治·加布里·斯托克斯:维多利亚时代的名流

乔治·加布里·斯托克斯是维多利亚时代科学的代表人物之一。他的研究领域遍及流体动力学、光学、光谱学和数学等学科。在剑桥卢卡斯数学讲座教授位置上执教54年,培养出麦克斯韦、瑞利勋爵和J.J.汤姆逊这样的科学大师。同时他还在英国皇家学会担任要职,并能与性格各异的科学家友善相处。他的杰出成就也使他置身于维多利亚时代的名流之列。     

基于“自然选择”的系统主义生态伦理观的建构

生态危机的主要根源不在于人类中心主义,而在于人类错误理解了自然的本性及其与人类之间的关系。生态系统是一个"活着的"自组织控制系统,人类应该像对待"生命"那样对待它,否则在"自然选择"动力驱使下,它可能为了自身的生存而抛弃人类。生态系统健康与服务的可持续实现可以成为评判人类行为道德与否的标准。破坏生态系统健康将损害当前及未来人类整体利益,是不道德的。在维护生态系统健康前提下,利用其服务功能,才能保证未来人类被自然选中存活下来,不被自然淘汰。这是一种弱人类中心主义生态伦理观、一种社会层面的规范伦理,基于"经验论"的功利主义构成其元伦理学。     

中国自然辩证法研究会第五次全国代表大会关于修改章程的说明

各位代表,各位理事:受常务理事会委托,对我会<章程>进行修改,现将有关修改意见报告如下,请予审议.发给大家修改后的<中国自然辩证法研究会章程>是经常务理事会和朱训同志认真修改定稿的.经代表讨论后,集中大家的意见,再进行修改,然后提交代表大会通过.     

Minimal Sample Size in the Group Classification Problem

Bayes classification procedure for a group of independent vectors treated as a whole is considered. When the distributions are not specified, we obtain the bounds of the minimal sample size based on the Chernoff and the Bhattacharyya distances between the populations. The case of the normal distribution is also discussed.     

论社会选择与自然选择之张力

社会选择与自然选择分别作为社会与自然界的内在规定,因后者的对象性关系而生成相互规约或“牵引”的张力。社会选择与自然选择张力的非和谐本性,在时空维直接表达为强弱地位的交替与置换,并以社会形态为中介,充分展示在历史发展的逻辑中。在现实性上,社会进化最终只能赖于社会选择,否则将出现“社会返祖”。社会选择的应当取向不是“社会与自然的协调”,而是社会与自然的无限“磨合”。     

自然选择新图景——兼谈必然性和偶然性在生物进化中的作用

本文从分析达尔文自然选择与现实自然界生物多样性的矛盾,及与中性学说之争论出发,提出自然选择的实质是“最劣必汰,差别保存”的新图景。同时,对生物进化中的必然性和偶然性进行探讨。     

技术进化的社会选择

本文分析了技术进化特征，即技术产物的多样性、技术发展的延续性与非延续性、技术系统的自组织性；探讨了技术进化社会选择的三种形式，即市场选择、政府选择、文化选择；论证了技术进化与社会选择间的互动关系，认为技术进化与社会选择间的相互作用推动着技术与人类的共同进步，技术进化与人类进化之间的协同共进是完全可能的。     

选择与进化非决定性

决定论的进化观无论作为实在性还是解释性上的理论需要,一直占据着主导地位。自从围绕分子水平进化机制讨论的兴起,便出现了关于进化非决定论的争论,并且很快成为关于实在论的争论。布兰登等基于解释性渗透观念对进化非决定论所进行的辩护在这场争论中受到诸多责难,因此这里将从另外一种角度探讨非决定性要素的渗透,进而为进化非决定论观点提供一种实在论的基础。     

1991--2006年中国大陆科研机构在所选代表性期刊发表论文统计

研究论文是基础研究成果的主要表现形式之一,一个国家或科研机构发表特别是在高水平学术期刊上发表论文的情况可从一个角度反应该国家或科研机构的基础研究状况和水平。基于此,本文选择了一些高水平的学术期刊,统计分析了我国科研机构（不包括香港、澳门和台湾的科研机构）在这些期刊发表论文的情况,以期从一个侧面反映我国基础研究的发展状况和水平。     

关于“胞宫”名词选定的讨论

中医药学名词中,表述“女性孕育胎儿与定期产生月经的内生殖器官”这一概念的名词较多,使用较为混乱,必须做出取舍。最早的命名见于《黄帝内经·素问》,称为女子胞,但此词在以后的中医学书籍中使用不多。后来又出现了“子宫”、“胞宫”、“子脏”等多种称谓,根据现今的中医妇产科临床使用情况及现行的国家标准来看,“胞宫”一词使用为多。而且,此名词也比“女子胞”更为上口,更容易理解与交流。因此,选择为“胞宫”作为正名,比较合适。     

试论基于国家创新系统的创新优势战略--以中国软件产业发展为例

通过提出一种新型的国家创新系统理论框架,论证了国家智能及其保障机制是推动国家发展的首要因素.因此,创新优势战略成为首选的国家发展战略.国家智能是国家决策和解决重要问题的能力,是集思广益制度汇集的学界、政界、工商界等社会各界有识之士的聪明才智.同时也论证了社会科学、交叉科学和软科学的至关重要性.最后运用新型的国家创新系统理论框架和观点,对中国软件产业发展进行了案例研究.     

Power and Sample Size Computation for Wald Tests in Latent Class Models

Latent class (LC) analysis is used by social, behavioral, and medical science researchers among others as a tool for clustering (or unsupervised classification) with categorical response variables, for analyzing the agreement between multiple raters, for evaluating the sensitivity and specificity of diagnostic tests in the absence of a gold standard, and for modeling heterogeneity in developmental trajectories. Despite the increased popularity of LC analysis, little is known about statistical power and required sample size in LC modeling. This paper shows how to perform power and sample size computations in LC models using Wald tests for the parameters describing association between the categorical latent variable and the response variables. Moreover, the design factors affecting the statistical power of these Wald tests are studied. More specifically, we show how design factors which are specific for LC analysis, such as the number of classes, the class proportions, and the number of response variables, affect the information matrix. The proposed power computation approach is illustrated using realistic scenarios for the design factors. A simulation study conducted to assess the performance of the proposed power analysis procedure shows that it performs well in all situations one may encounter in practice.     

Variable Selection for Clustering and Classification

As data sets continue to grow in size and complexity, effective and efficient techniques are needed to target important features in the variable space. Many of the variable selection techniques that are commonly used alongside clustering algorithms are based upon determining the best variable subspace according to model fitting in a stepwise manner. These techniques are often computationally intensive and can require extended periods of time to run; in fact, some are prohibitively computationally expensive for high-dimensional data. In this paper, a novel variable selection technique is introduced for use in clustering and classification analyses that is both intuitive and computationally efficient. We focus largely on applications in mixture model-based learning, but the technique could be adapted for use with various other clustering/classification methods. Our approach is illustrated on both simulated and real data, highlighted by contrasting its performance with that of other comparable variable selection techniques on the real data sets.     

Subspace Projection for Multivariate Selection Problems

A new set of derived variables is proposed for exhibiting grouped multivariate data in a small number of dimensions, in such a way as to highlight `extremeness' of one or more groups relative to the rest of the data. Such display can provide a useful exploratory tool in multivariate ranking and selection problems. We explore four possible measures of `extremeness', and suggest which one is best for practical application. We show that the technique can be used to derive either orthogonal or uncorrelated dimensions for any type of input data, and we give an illustrative example of its use.     

名词收选的几点体会

名词审定中最为重要的两项任务是:(1)名词选择务求齐全;(2)定名力争准确。名词收选是名词审定工作中的第一项关键性基础工作。本文重点介绍有关名词收选的几点体会。     

大学科技园的网络本质和战略选择

成功的大学科技园表现出来的本质特征是，它具有“关系的”、“结构的”、“无中心的”和“开放的”特性，并成为可扩展性的创新网络。一旦大学科技园发展成为创新网络，就能够通过其网络效应、组织协同和“互利共生”机制．推动企业的孵化和成长，增加创新型企业的收益，提高资源利用效率，成为创新型企业和创业者最好的“栖息地”。在重新审视大学科技园建设过程中政府和市场、技术和资本、企业与网络组织的关系的基础上，把这些关系放在体制构架中来理解，我国大学科技园建设应坚持政府建设网络通路、网络富集创新要素和资本追逐高新技术的战略原则。     

谈国家自然科学基金面上项目申请的选题

通过对2002—2004年间不予资助的2406项面上项目的12030份评议函进行阅读和比较分析,发现专家不同意资助项目的理由虽然有多种多样,但专家对申请项目的评价,比较注重的还是项目的选题,占问题的29.99%。本文就此从7个方面———问题的提出、选题的目的、选题的过程、基础研究的选题、应用基础研究的选题、选题与创新、结语———浅议了国家自然科学基金面上项目申请的选题,希望能在选题理念与实践两方面给申请者一些启示。     

Using Neural Network Analysis to Define Methods of DINA Model Estimation for Small Sample Sizes

The DINA model is a commonly used model for obtaining diagnostic information. Like many other Diagnostic Classification Models (DCMs), it can require a large sample size to obtain reliable item and examinee parameter estimation. Neural Network (NN) analysis is a classification method that uses a training dataset for calibration. As a result, if this training dataset is determined theoretically, as was the case in Gierl’s attribute hierarchical method (AHM), the NN analysis does not have any sample size requirements. However, a NN approach does not provide traditional item parameters of a DCM or allow for item responses to influence test calibration. In this paper, the NN approach will be implemented for the DINA model estimation to explore its effectiveness as a classification method beyond its use in AHM. The accuracy of the NN approach across different sample sizes, item quality and Q-matrix complexity is described in the DINA model context. Then, a Markov Chain Monte Carlo (MCMC) estimation algorithm and Joint Maximum Likelihood Estimation is used to extend the NN approach so that item parameters associated with the DINA model are obtained while allowing examinee responses to influence the test calibration. The results derived by the NN, the combination of MCMC and NN (NN MCMC) and the combination of JMLE and NN are compared with that of the well-established Hierarchical MCMC procedure and JMLE with a uniform prior on the attribute profile to illustrate their strength and weakness.