Regularized covariance matrix estimation under the common principal components model

The common principal components (CPC) model provides a way to model the population covariance matrices of several groups by assuming a common eigenvector structure. When appropriate, this model can provide covariance matrix estimators of which the elements have smaller standard errors than when using either the pooled covariance matrix or the per group unbiased sample covariance matrix estimators. In this article, a regularized CPC estimator under the assumption of a common (or partially common) eigenvector structure in the populations is proposed. After estimation of the common eigenvectors using the Flury–Gautschi (or other) algorithm, the off-diagonal elements of the nearly diagonalized covariance matrices are shrunk towards zero and multiplied with the orthogonal common eigenvector matrix to obtain the regularized CPC covariance matrix estimates. The optimal shrinkage intensity per group can be estimated using cross-validation. The efficiency of these estimators compared to the pooled and unbiased estimators is investigated in a Monte Carlo simulation study, and the regularized CPC estimator is applied to a real dataset to demonstrate the utility of the method.     

Controlling the false-discovery rate by procedures adapted to the length bias of RNA-Seq

In RNA-Seq experiments, the number of mapped reads for a given gene is proportional to its expression level and length. Because longer genes contribute more sequencible fragments than do shorter ones, it is expected that even if two genes have the same expression level, the longer gene will have a greater number of total reads. This characteristic creates a length bias such that the proportion of significant genes increases with the gene length. However, genes with a long length are not more biologically meaningful than genes with a short length. Therefore, the length bias should be properly corrected to determine the accurate list of significant genes in RNA-Seq. For this purpose, we proposed two multiple-testing procedures based on a weighted-FDR and a separate-FDR approach. These two methods use prior information on differential gene length while keeping the false-discovery rate (FDR) controlled at $\alpha$. In the weighted-FDR controlling procedure, we incorporated prior weights for the length of each gene. These weights increase the power when the gene’s length is short and decrease the power when its length is long. In the separate-FDR controlling procedure, we sequentially ordered all genes according to their lengths and then split these genes into two subgroups of short and long genes. The adaptive Benjamini–Hochberg procedure was then performed separately for each subgroup. The proposed procedures were compared with existing methods and evaluated in two numerical examples and one simulation study. We concluded that the weighted $p$-value procedure properly reduced the length bias of RNA-Seq.     

经济一体化对地区安全的影响——以南方共同市场为例

经济一体化与地区安全之间有何关系?安全关系原本比较紧张的国家之间能否进行地区经济一体化合作?经济一体化对地区安全有怎样的影响?很多地区一体化的实践对此都难以做出回答。然而通过分析南方共同市场的已有经验,我们发现,安全关系相对紧张的国家之间不仅能够进行经济一体化合作,而且这种合作对改善地区安全有着重要的促进作用。南方共同市场成功实现了经济关系对安全关系的"外溢",使成员国之间的安全关系得到改善和发展。     

香港基本法司法适用中的争议——从基本法与普通法关系的角度

香港回归以来,基本法在实行普通法传统的香港法院的司法适用中,出现了以普通法方法适用基本法及以普通法解释基本法的现象,突出体现在香港法院违反基本法审查权和基本法解释权的行使上。造成这一现象的原因包括基本法与普通法法律推理和法律思维方式的差异,全国人大常委会与香港法院立法解释、司法解释的分歧,基本法有关制度和制度执行的缺失。应正确处理普通法和基本法的关系,推动普通法事后审查制度的常态化,维护全国人大常委会的审查权等方面规范基本法的司法适用。     

“人道其里,抒情其华”——浅论汪曾祺小说

作为乡土小说的代表作家,汪曾祺在当代文坛上的姿态和地位是特殊而重要的。本文试图从汪曾祺小说的世俗精神出发,探讨其作品在空前繁荣的新时期文学中独树一帜的精神特质。     

气候变化背景下的全球正义探析

享受工业化以及增加温室气体排放益处的人往往并不是那些受气候变化负面影响最大的人,气候变化利益与负担的不公平分配正是全球正义的关注范围。全球气候变化的主要肇因是发达国家的累积排放,因此,发达国家对解决气候变化负有特殊的义务,这种特殊义务就是＂共同但有区别的责任＂。要使全球气候正义成为可能,发达国家就必须放弃＂以邻为壑＂的固有观念,将分配正义的共同体扩展到全球范围,建立全球正义共同体。     

民族文化心理概念辨析——兼论民族心理学学科特性的显现

民族心理学作为心理学分支,它的学科特性的显现在于服务民族的发展与共同生活,狭义的民族文化心理是其研究的重要内容。从内涵界定:狭义的民族文化心理指受民族历史地积淀的社会文化影响而形成的对人、对事、对物等客观存在和关系的心理行为反应倾向和方式;其外延包括民族的价值观念、态度特征、意志特征、情绪特征、思维方式。相应地,研究方法需从心理学主流的实证研究范式中解脱出来,从相关学科中吸取和借鉴经验。     

民国时期官方确定汉民族共同语标准音的历史回顾与思考

作者回顾了民国时期政府确定汉民族共同语标准音历史进程的3个阶段，并运用语言规划学、政策学和汉语言文字学等相关学科理论，分析了每个阶段的具体特点，涉及了语言规划者的价值观对语言政策的决定作用、公众的政策诉求对语言规划者态度改变的作用、语言文字工作者对语言规划的影响、政府对语言规划工作的推动等诸多理论和实践问题。     

试析雷蒙·威廉斯的“文化”定义

威廉斯的“文化”定义一面为学界津津乐道、引为正典,一面却又遭遇着断章取义、不求甚解的粗暴误读。因此,有必要重新回返1950年代后期英国的社会历史情境,在多重结构性因素的参照之下,读解并勾连起威廉斯早期文本中的“文化”思想,进而探析威廉斯的“文化”定义之于“文化研究”的意义。     

《察世俗每月统记传·序》常见引文勘正与分析

在讨论了记载《察世俗每月统记传》序言出版概况的基础上,以影印资料为依据,订正了《中国报学史》(1955年版)及其他常见引述文献记载的错误。分析表明,造成差错的主要因素为原始资料在转录过程中致错和转引文献校对差错以及臆测文献原意错误等。