四级网考对大学英语教学的反拨作用

大学英语四级网考的铺开是大学英语教学改革的一项重要内容,它在考试媒介、题型设计、题材选择、考查重心等方面都作出了调整。考试对教学起到一定的反拨作用。大学英语教师要研究四级网考所体现的教学理论,转变教学理念,利用网络教学资源,探索如何以测试为动因培养学生的英语综合应用能力、可持续发展的自主学习能力以及计算机硬件操作能力。     

同轴波导FEL放大器的非线性分析

以同轴波导、同轴混合磁铁摇摆器为模型,导出了自洽的注波三维非线性方程组,在考虑了电子初始速度零散效应、空间电荷波效应的影响及电子注在互作用区入口处的绝热压缩过程的基础上,编制了相应的计算软件。同时,通过数值分析的方法研究了自由电子激光器的饱和效率、频带宽度等高频特性和变参数摇摆器结构对延缓饱和、提高效率的作用。     

中国加入WTO正，负效应的重新阐释

我国加入WTO有利也有弊.其正效应主要表现在增加我国在对外贸易谈判中的主动权,促进制度创新与观念更新,重塑我国企业的造新精神,迅速改变我国服务贸易领域的经营面貌.其短期内的负效应表现在可能降低外汇储备水平,使企业经营、就业和证券行业陷入困境.     

Alternative estimation methods for identifying contagion effects in dynamic social networks: A latent-space adjusted approach

Contagion effects, also known as peer effects or social influence process, have become more and more central to social science, especially with the availability of longitudinal social network data. However, contagion effects are usually difficult to identify, as they are often entangled with other factors, such as homophily in the selection process, the individual’s preference for the same social settings, etc. Methods currently available either do not solve these problems or require strong assumptions. Following Shalizi and Thomas (2011), I frame this difficulty as an omitted variable bias problem, and I propose several alternative estimation methods that have potentials to correctly identify contagion effects when there is an unobserved trait that co-determines the influence and the selection. The Monte-Carlo simulation results suggest that a latent-space adjusted estimator is especially promising. It outperforms other estimators that are traditionally used to deal with the unobserved variables, including a structural equation based estimator and an instrumental variable estimator.     

Racial diversity, minority concentration, and trust in Canadian urban neighborhoods

Using a sample of 42,329 respondents nested within 4254 Canadian urban neighborhoods, this study demonstrates the conceptual and empirical importance of making a distinction between neighborhood racial diversity and minority concentration, and examines how each is uniquely associated with trust. Our analysis shows that at a given level of racial minority concentration, Whites are more trusting when their minority neighbors are more evenly distributed across racial minority groups. Meanwhile, Whites are less trusting as the neighborhood share of racial minorities increases. Overall, the effect of racial minority concentration tends to prevail over that of racial diversity.     

Deconvolution methods for non-parametric inference in two-level mixed models

Summary.  We develop a general non-parametric approach to the analysis of clustered data via random effects. Assuming only that the link function is known, the regression functions and the distributions of both cluster means and observation errors are treated non-parametrically. Our argument proceeds by viewing the observation error at the cluster mean level as though it were a measurement error in an errors-in-variables problem, and using a deconvolution argument to access the distribution of the cluster mean. A Fourier deconvolution approach could be used if the distribution of the error-in-variables were known. In practice it is unknown, of course, but it can be estimated from repeated measurements, and in this way deconvolution can be achieved in an approximate sense. This argument might be interpreted as implying that large numbers of replicates are necessary for each cluster mean distribution, but that is not so; we avoid this requirement by incorporating statistical smoothing over values of nearby explanatory variables. Empirical rules are developed for the choice of smoothing parameter. Numerical simulations, and an application to real data, demonstrate small sample performance for this package of methodology. We also develop theory establishing statistical consistency.     

应当强调办案的社会效果

法律的概括性、抽象性、发展性等特点决定了有必要强调办案的社会效果。强调办案的社会效果有利于制约司法自由裁量权,是新时期司法工作的必然要求。     

人口流动对健康的影响

在当今世界,人口流动的重要性日益突出,其对健康的影响也日益扩大。尽管涉猎人口流动与健康这个交叉领域的学者很多。但致力于考察前者对后者的影响的作品却为数不多。原因在于流行病学的视角局限了大家的视野。为了扭转这种局面,笔者强调指出,要考察人口流动对健康的影响,必须比较流动前后人群在健康状况方面的变化。以此为导向。在回顾文献的基础上。笔者初步回答了两个问题：流动对健康的影响体现在何处？这些影响得以实现的机制是什么？最后,笔者还为将来的研究提供了一些建议。     

医疗保险对农村居民家庭消费的影响分析--基于不同收入层级的跨地区比较

利用2009、2010农村固定观察点数据,分析了医疗保险对不同地区、不同收入层级的农村居民家庭医疗消费支出和非医疗消费支出的影响。实证结果表明：医疗保险对农村居民家庭的医疗类消费不存在显著影响,对非医疗类消费支出则存在显著的正向促进作用。分地区来看,医疗保险对东西部地区农村居民家庭医疗类消费的影响差异显著,对东中部地区农村居民家庭非医疗类消费支出的影响同样差异显著;分收入层级来看,医疗保险对家庭医疗类消费的影响在不同收入层级的农村居民家庭之间不存在显著差异,但对非医疗类消费支出的影响在不同收入层级之间差异显著。此外,商业医疗保险作为医疗保险体系的重要组成部分,对促进农村消费起到带动作用。最后,本文从加大政府补贴和完善保障机制两个方面提出政策建议以期有效降低农村居民家庭超常的预防性储蓄,促进农村居民家庭消费。     

Response of sensitive behaviors to frequent measurement

We study the influence of frequent survey measurement on behavior. Widespread access to the Internet has made important breakthroughs in frequent measurement possible—potentially revolutionizing social science measurement of processes that change quickly over time. One key concern about using such frequent measurement is that it may influence the behavior being studied. We investigate this possibility using both a population-based experiment with random assignment to participation in a weekly journal for twelve months (versus no journal) and a large-scale, population-based, journal-keeping study with weekly measurement for 30 months. Results reveal few of the measured behaviors are correlated with assignment to frequent measurement. Theoretical reasoning regarding the likely behavioral response to frequent measurement correctly predicts domains most vulnerable to this possibility. Overall, however, we found little evidence of behavioral response to frequent measurement.