A note on measures of similarity based on centrality

This note presents a measure of similarity between connected nodes in terms of centrality based on Euclidean distances, and compares it to ‘assortative mixing’ [Newman, M.E.J., 2002. Assortative mixing in networks. Physical Review Letters 89, 208701], which is based on Pearson correlation coefficient. This study suggests that the measure based on Euclidean distances may be more appropriate for relatively smaller (N < 500) and denser networks.     

Electronic Play,Study, Communication,and Adolescent Achievement, 2003–2008

Adolescents’ time spent messaging, exploring websites, and studying on the computer increased between 2003 and 2008. Using data from the Panel Study of Income Dynamics Child Development Supplement, this study examines how such changes have influenced individual achievement and behavior from childhood to adolescence. Greater communications and Internet web time proved detrimental to vocabulary and reading whereas the increased use of computer games was associated with increased reading and problem‐solving scores, particularly for girls and minority children. Increased use of the computer for studying was associated with increased test scores for girls, but not boys. The consequences are more benign than many feared. Groups that have traditionally used the computer less (girls, minority children) appear to benefit from greater use.     

A Diversity Index for Model Space Selection in the Estimation of Benchmark and Infectious Doses via Model Averaging

In chemical and microbial risk assessments, risk assessors fit dose‐response models to high‐dose data and extrapolate downward to risk levels in the range of 1–10%. Although multiple dose‐response models may be able to fit the data adequately in the experimental range, the estimated effective dose (ED) corresponding to an extremely small risk can be substantially different from model to model. In this respect, model averaging (MA) provides more robustness than a single dose‐response model in the point and interval estimation of an ED. In MA, accounting for both data uncertainty and model uncertainty is crucial, but addressing model uncertainty is not achieved simply by increasing the number of models in a model space. A plausible set of models for MA can be characterized by goodness of fit and diversity surrounding the truth. We propose a diversity index (DI) to balance between these two characteristics in model space selection. It addresses a collective property of a model space rather than individual performance of each model. Tuning parameters in the DI control the size of the model space for MA.     

A Social Networks Approach to Public Relations on Twitter: Social Mediators and Mediated Public Relations

This study proposes theoretical and practical frameworks to systematically examine mediated public relations in social media spaces. We applied a social network conceptual framework to identify and characterize social mediators that connect the US State Department with its international public. The results showed that social mediators vary in terms of their formality and interdependence. Formal social mediators were primarily US government agencies while informal social mediators were nongovernmental organizations (NGOs) and individuals. Notably, relationships with populations in the Middle East and North Africa were mediated primarily by informal actors, and formal mediators played a key role in connecting the public with everywhere else in the world. Government-related formal mediators and informal social mediators showed similar levels of bilateral relationships. In contrast, news media, the most traditional public relations mediators, were rarely found as social mediators and demonstrated the most unilateral relationships.     

An Empirical Examination of Characteristics of Mexican Migrants to Metropolitan and Nonmetropolitan Areas of the United States*

Abstract This research examines differences between those Mexican migrants choosing metropolitan destinations and those choosing destinations outside metropolitan areas of the United States. Using general estimating equations, the study presents data indicating that since the 1960s migrants choosing rural destinations are less fluent in English, slightly older, much less educated, far more likely to be unskilled, more likely to be married, and more likely to be undocumented. The picture is more complex when consideration is restricted to those migrants arriving in rural areas since the passage of the North American Free Trade Agreement. These migrants are far more likely to be single, have more education but have less English fluency, have less work experience, and have less family experience with migration to the United States. They are more likely to come from small towns and rural areas of Mexico.     

Internationalization and Performance of Firms in China: Moderating Effects of Governance Structure and the Degree of Centralized Control

This study proposes necessary modifications to the existing internationalization–performance relationship to meet the idiosyncrasies of China-specific contexts. We first hypothesize an S-shaped internationalization–performance relationship as the baseline and then investigate the moderating effects of a firm's governance structure and the degree of centralized government control on the relationship between its internationalization and performance. The results, based on a longitudinal sample of manufacturing firms in China for the 2001–2007 period, indicate that (1) the S-shaped internationalization–performance relationship holds for firms in China; (2) the governance structure moderates the internationalization–performance relationship such that increased profitability through internationalization is more likely for modernized firms than for their conventional local counterparts; and (3) the degree of centralized control moderates the internationalization–performance relationship such that increased profitability through internationalization is more likely for firms affiliated with higher level governments than for those affiliated with lower-level governments.     

Temporal Disaggregation: Methods,Information Loss,and Diagnostics

This research provides a generalized framework to disaggregate lower-frequency time series and evaluate the disaggregation performance. The proposed framework combines two models in separate stages: a linear regression model to exploit related independent variables in the first stage and a state–space model to disaggregate the residual from the regression in the second stage. For the purpose of providing a set of practical criteria for assessing the disaggregation performance, we measure the information loss that occurs during temporal aggregation while examining what effects take place when aggregating data. To validate the proposed framework, we implement Monte Carlo simulations and provide two empirical studies. Supplementary materials for this article are available online.     

走向一种绿色意识形态

与价值观不同，意识形态既是规范性的又是描述性的，或者说，既是价值评估性的也是知识追求性的。事实与价值之间的关系，被传统地以“二分法”的方式加以构建，实际上二者是一种互补关系，但这也并不意味着对矛盾关系的否认。一种建立在摆脱教条主义的唯物主义基础上的绿色理论，更有利于开展一种行之有效的实践，而这或许是绿色运动可以从马克思主义那里继承的最为重要的遗产。如果生态主义要想成为一种有影响的意识形态，就必须发展一种“绿色实践观”，创建“理论-实践”的统一体，并借助包含着价值考量在内的“中介”来跨越二者之间的鸿沟。