A dimensionality reduction method of continuous dependent variables based supervised Laplacian eigenmaps

Dimensionality reduction is one of the important preprocessing steps in high-dimensional data analysis. In this paper we propose a supervised manifold learning method, it makes use of the information of continuous dependent variables to distinguish intrinsic neighbourhood and extrinsic neighbourhood of data samples, and construct two graphs according to these two kinds of neighbourhoods. Following the idea of Laplacian eigenmaps, we reveal that on the low-dimensional manifold the neighbourhood structure can be preserved or even improved. Our approach has two important characteristics: (i) it uses dependent variables to find an informative low-dimensional projection which is robust to noisy independent variables and (ii) the objective function simultaneously enlarges the distance between dissimilar samples and pushes similar samples close to each other according to the graph constructed with the help of continuous dependent variables. Our experiments demonstrate that the effectiveness of our method is over their traditional rivals.     

Heating up the debate? Measuring fragmentation and polarisation in a German climate change hyperlink network

Research into polarisation on the internet has so far primarily focused on contentious issues and yielded contradictory results. Shifting the focus to a non-contentious setting, this article combines community detection with brokerage analysis and exponential random graph models to assess the degree of polarisation at different levels of a German hyperlink network on climate change. Although homophily accounts for a moderate degree of polarisation at the top level of the network, the communities reveal that other factors prove more decisive in shaping its structure and the article thus contributes to a more refined understanding of the nature of online polarisation.     

新生代农民工与城市居民的社会距离分析

本文运用2008年宁波城市新生代农民工调查数据,对新生代主体视角下与城市居民社会距离的现状及影响凶素进行了探讨。分析结果发现：以新生代农民工为主体视角的社会距离建立在融入意愿和排斥预期两个层面基础上;与上一代农民工相比．新生代农民工与城市居民的社会距离在增大。社会经济地位、社会关系网络、居住空间和社会文化会显著影响新生代农民丁的社会距离。要促进新生代农民丁的城市融人,缩短新生代农民工与城市居民的社会距离,需要新生代农民工、城市居民、政府和社会等多方行动者的共同努力。     

Univariate and multivariate models of positive and negative networks: Liking,disliking, and bully–victim relationships

Three relations between elementary school children were investigated: networks of general dislike and bullying were related to networks of general like. These were modeled using multivariate cross-sectional (statistical) network models. Exponential random graph models for a sample of 18 classrooms, numbering 393 students, were summarized using meta-analyses. Results showed (balanced) network structures with positive ties between those who were structurally equivalent in the negative network. Moreover, essential structural parameters for the univariate network structure of positive (general like) and negative (general dislike and bullying) tie networks were identified. Different structures emerged in positive and negative networks. The results provide a starting point for further theoretical and (multiplex) empirical research about negative ties and their interplay with positive ties.     

Collapsibility for Directed Acyclic Graphs

Abstract.  Collapsibility means that the same statistical result of interest can be obtained before and after marginalization over some variables. In this paper, we discuss three kinds of collapsibility for directed acyclic graphs (DAGs): estimate collapsibility, conditional independence collapsibility and model collapsibility. Related to collapsibility, we discuss removability of variables from a DAG. We present conditions for these three different kinds of collapsibility and relationships among them. We give algorithms to find a minimum variable set containing a variable subset of interest onto which a statistical result is collapsible.     

A weighted Harrell–Davis distance test with applications to censored data

Consider the standard treatment-control model with a time-to-event endpoint. We propose a novel interpretable test statistic from a quantile function point of view. The large sample consistency of our estimator is proven for fixed bandwidth values theoretically and validated empirically. A Monte Carlo simulation study also shows that given small sample sizes, utilization of a tuning parameter through the application of a smooth quantile function estimator shows an improvement in efficiency in terms of the MSE when compared to direct application of classic Kaplan–Meier survival function estimator. The procedure is finally illustrated via an application to epithelial ovarian cancer data.     

网络沟通下政府形象“距离悖论”的解析及应对

网络沟通的兴起,使政府形象塑造的环境发生了变化,政府形象的“距离悖论”出现新特点,其突出表现是,民众对政府形象的评价与该级政府同民众的距离（包括空间距离和时间距离）成反比。在网络沟通下,形象良好的政府须具有回应性,倡导科技领先,强调参与和协作以及具有预见性,因此,政府应从树立形象意识、完善电子政府工程、提升政府媒体公关能力和公信力以及提高危机处理能力等方面着手,来应对政府形象的“距离悖论”,以塑造良好的自身形象。     

我国老年人长期护理研究知识图谱分析

利用可视化分析软件CiteSpace,对从中国知网数据库中截取的1999—2019年CSSCI与核心期刊797篇文献进行文献计量分析;通过关键词共现、时区视图及突现图,构建我国老年人长期护理研究的知识图谱,展示近20年来我国老年人长期护理研究的研究热点、演化路径及研究趋势等。总体来看,我国老年人长期护理研究稳步推进,研究成果日益增多,研究内容不断深化;高校是长期护理研究的主力军,但学者间、研究机构间的合作较少,当下尚未形成较严密的学术研究网络;相关研究具有较强的时代性特征,且在很大程度上受到政府政策的驱动和引导;研究的本土化与精细化趋势较明显。     

典型液压系统在功率键合图中的应用

在工程系统动态特性的理论研究中,常用的方法有传递函数法和状态方程法。但对液压系统来说,具有一定的局限性。而功率键合图,则可以直接从液压原理图有条不紊地画出来。本文给出了一典型液压系统的功率键合图,同时给出了影响系统动态特性的各个因素和系统的方程。