Model-based clustering for social networks

Summary.  Network models are widely used to represent relations between interacting units or actors. Network data often exhibit transitivity, meaning that two actors that have ties to a third actor are more likely to be tied than actors that do not, homophily by attributes of the actors or dyads, and clustering. Interest often focuses on finding clusters of actors or ties, and the number of groups in the data is typically unknown. We propose a new model, the latent position cluster model , under which the probability of a tie between two actors depends on the distance between them in an unobserved Euclidean 'social space', and the actors' locations in the latent social space arise from a mixture of distributions, each corresponding to a cluster. We propose two estimation methods: a two-stage maximum likelihood method and a fully Bayesian method that uses Markov chain Monte Carlo sampling. The former is quicker and simpler, but the latter performs better. We also propose a Bayesian way of determining the number of clusters that are present by using approximate conditional Bayes factors. Our model represents transitivity, homophily by attributes and clustering simultaneously and does not require the number of clusters to be known. The model makes it easy to simulate realistic networks with clustering, which are potentially useful as inputs to models of more complex systems of which the network is part, such as epidemic models of infectious disease. We apply the model to two networks of social relations. A free software package in the R statistical language, latentnet, is available to analyse data by using the model.     

论程序设计类精品课程建设

精品课程建设是高等学校教学质量与教学改革工程中重要的项目之一。文章介绍了国家精品课程建设的宗旨和精品课程评审的指标体系，并着重从教学团队、教学内容、教学条件、教学方法与手段、教学效果、政策支持等方面讨论了程序设计类精品课程建设的具体措施。     

Identifying Dispersion Effects in Robust Design Experiments—Issues and Improvements

The two experimental methods most commonly used for reducing the effect of noise factors on a response of interest Y aim either to estimate a model of the variability (V(Y), or an associated function), that is transmitted by the noise factors, or to estimate a model of the ratio between the response (Y) and all the control and noise factors involved therein. Both methods aim to determine which control factor conditions minimise the noise factors' effect on the response of interest, and a series of analytical guidelines are established to reach this end. Product array designs allow robustness problems to be solved in both ways, but require a large number of experiments. Thus, practitioners tend to choose more economical designs that only allow them to model the surface response for Y. The general assumption is that both methods would lead to similar conclusions. In this article we present a case that utilises a design based on a product design and for which the conclusions yielded by the two analytical methods are quite different. This example casts doubt on the guidelines that experimental practice follows when using either of the two methods. Based on this example, we show the causes behind these discrepancies and we propose a number of guidelines to help researchers in the design and interpretation of robustness problems when using either of the two methods.     

A Non-parametric Test for Generalized First-order Autoregressive Models

We derive a non-parametric test for testing the presence of V(X_i,ε_i) in the non-parametric first-order autoregressive model X_i+1=T(X_i)+V(X_i,ε_i)+U(X_i)ε_i+1, where the function T(x) is assumed known. The test is constructed as a functional of a basic process for which we establish a weak invariance principle, under the null hypothesis and under stationarity and mixing assumptions. Bounds for the local and non-local powers are provided under a condition which ensures that the power tends to one as the sample size tends to infinity.The testing procedure can be applied, e.g. to bilinear models, ARCH models, EXPAR models and to some other uncommon models. Our results confirm the robustness of the test constructed in Ngatchou Wandji (1995) and in Diebolt & Ngatchou Wandji (1995).     

Food safety regulation,economic impact assessment and quantitative methods

Together with a call for more efficient regulations in the EU, there is a growing demand for transparency in the evaluation techniques to assess and predict their effects. This article explores the potential impacts of food safety regulations and discusses the quantitative methods used in the policy evaluation literature. Along with the strengths and limitations of each method, this review highlights other transversal issues relevant to the assessment strategies. Among these are the imbalance between ex ante and ex post evaluation, the lack of adequate data, the difficulty of estimating the dynamic effects of regulations, and the possibility of endogenous relationships.     

加强学生党员入党后教育管理探索

目前高校学生党建工作发展迅速，成果显著，但在学生党员入党后的教育管理上仍存在管理力量薄弱、支部作用发挥不够、监督考核制度滞后等问题。当前高校可通过建立专兼职党建队伍，深化党员继续教育，切实发挥基层支部作用，健全考核监督制度等方式加强学生党员入党后的教育管理，完善高校党建机制。     

关于三角形内角和定理证明的教法反思

新课程标准的出现，意味着教法坐标体系或者教学深层价值目标的建立．但是在教材与标准之间有如一片广阔的创造地带，它提供给教师前所未有的展示教学智慧的空间，而在创新教法的构想和实施之前，需要对传统教法、新课程标准、教材等有清醒的认识．通过对三角形内角和定理证明教法的剖析，提出了有关新的教学智慧的思考和教学构想．     

Bayesian analysis of human movement curves

Summary.  We consider the Bayesian analysis of human movement data, where the subjects perform various reaching tasks. A set of markers is placed on each subject and a system of cameras records the three-dimensional Cartesian co-ordinates of the markers during the reaching movement. It is of interest to describe the mean and variability of the curves that are traced by the markers during one reaching movement, and to identify any differences due to covariates. We propose a methodology based on a hierarchical Bayesian model for the curves. An important part of the method is to obtain identifiable features of the movement so that different curves can be compared after temporal warping. We consider four landmarks and a set of equally spaced pseudolandmarks are located in between. We demonstrate that the algorithm works well in locating the landmarks, and shape analysis techniques are used to describe the posterior distribution of the mean curve. A feature of this type of data is that some parts of the movement data may be missing—the Bayesian methodology is easily adapted to cope with this situation.     

论行政规范合法性审查的法学方法

行政规范合法性审查是指有权国家机关审查行政规范是否合法的活动，可分为合规则的审查、合原则的审查与合体系的审查三个阶段。基于各审查阶段的内容，可以选用相应的法学方法。合规则的审查需要采用文义解释等法解释学方法。合原则的审查，除了采取前述方法之外，还需要采用法原则识别法、法原则选择法以及法原则权衡法。合体系的审查则需综合运用前述方法重新审视、检查行政规范是否符合法体系的整体意义、脉络和精神。     

法家的＂以术治吏＂与企业的刚性管理

从人性的高度上揭示法家"以术治吏"的理论基础是本文的主要特点之一.与此同时,还详细论述了法家的"察奸之术"、"防奸之术"和"除奸之术"等,并且进一步对法家"以术治吏"的刚性管理做出了客观的评价.