话题识别与跟踪技术发展研究

话题识别与跟踪以大规模新闻流为研究对象,通过监控新闻报道描述的话题,发现新的用户感兴趣的信息并将涉及某个话题的新闻报道组织起来以某种方式呈现给用户。本文首先介绍话题识别与跟踪的主要任务、相关概念和评价方法,然后对话题识别国内外研究现状进行详细论述,最后对话题识别的发展趋势和未来的研究方向进行分析。     

网络环境下大学生心理健康教育现状及对策

互联网越来越成为现代社会人们生活、学习、日常交往不可或缺的重要组成部分,也给高校大学生心理健康教育带来严峻挑战。传统心理健康教育模式已不能解决网络虚拟空间的问题,灌输式的教育方法更不能满足大学生的心理需求。高校的心理健康教育应顺应时代发展潮流,及时调整和转换教育视角,增强学生对于网络复杂环境下的适应能力。具体策略是:更新教育理念,完善机制建设;打造教师团队,提高网络素养;优化教学资源,创新教学模式;实时观测动态,建立跟踪档案;抵制不良信息,净化网络环境。     

Ethical issues in tracking cellular telephones at an event

Early in 2007, the CSIR conducted an experiment to track the cellular telephones of a small group of people as they moved to and from an event, to test the viability of using such tracking to provide the participants with useful traffic information. This project raised a number of ethical issues, which prompted this paper and which we discuss here. These include:

• the ethics of modelling data, including the treatment of research participants;

• privacy and surveillance issues related to tracking the movement of people;

• the risks inherent in being tracked vs the benefits of being tracked; and

• the ethics related to sending messages to drivers.

We have reviewed the literature on ethics and used the results to assemble a check list of relevant ethical issues, adding a few of our own (i.e. a deontological ethics approach), against which the conduct of this research project was assessed. We also provide an overview of the experiment and the results obtained.     

上海创新社会治理加强基层建设跟踪研究

总体上看,"1+6"文件所重点关注的基层基础工作得到了加强、群众关注的重点问题得到了解决、基层队伍有了更好的工作环境.但在政策制定和政策实施方面仍须加强:在中观和宏观层面继续推进机构改革;设置具体指标,保障基层对下服务的导向;优化基层的具体工作流程;深化薪酬待遇改革;加大对街镇和居村委会工作队伍的职业能力培训.     

Predicting the Daily Covariance Matrix for S&P 100 Stocks Using Intraday Data—But Which Frequency to Use?

This article investigates the merits of high-frequency intraday data when forming mean-variance efficient stock portfolios with daily rebalancing from the individual constituents of the S&P 100 index. We focus on the issue of determining the optimal sampling frequency as judged by the performance of these portfolios. The optimal sampling frequency ranges between 30 and 65 minutes, considerably lower than the popular five-minute frequency, which typically is motivated by the aim of striking a balance between the variance and bias in covariance matrix estimates due to market microstructure effects such as non-synchronous trading and bid-ask bounce. Bias-correction procedures, based on combining low-frequency and high-frequency covariance matrix estimates and on the addition of leads and lags do not substantially affect the optimal sampling frequency or the portfolio performance. Our findings are also robust to the presence of transaction costs and to the portfolio rebalancing frequency.     

Auditory evoked potentials as a function of sleep deprivation

Event-related brain potentials (ERPs) were studied in subjects deprived of sleep over a 48-h test period to assess the effects of different durations of continuous wakefulness on ERP components and to determine whether changes in the ERP components were related to changes in performance. Forty subjects were randomly assigned to either an experimental (sleep deprived) group (n = 30) or a control (not sleep deprived) group (n = 10). For the experimental subjects, ERP and performance measures were obtained in four-h test blocks throughout the 48-h period. Performance was assessed using the Walter Reed performance assessment battery. The control subjects were tested at the same times except during designated sleep periods. Both performance and evoked potential measures showed systematic changes over the experimental test period in association with sleep deprivation, time of day, and repeated testing. The latency of the N2 component of the evoked potential covaried with throughput measures on the performance assessment battery across the 12 four-h test blocks of the experiment. These data suggest that ERPs reflect central processes that change across the sleep deprivation period and that ERP measures might be useful in assessment and prediction of performance degradation under adverse conditions such as sleep loss.     

How institutional context alters social reproduction dynamics: Ethnic track placement patterns in the U.S. and Germany

How does institutional context shape the way family dynamics, especially ethnic background and parental resources, affect track placement? We contrast the track placement patterns of immigrants and ethnic majority students in two countries marked by drastic differences in the social organization of schooling. Drawing on German (GSOEP) and U.S. (NELS) data, we find that, in general, more family resources pull students from lower to higher tracks, but ethnic inequalities in these resources favor the ethnic majority groups in both countries. In addition, institutional context conditions which parental resources shape educational outcomes, and how they do so. We find that the effects of parental ties exacerbate ethnic inequalities between whites and Latinos in the U.S.; whereas in Germany, parents’ community ties play a compensatory role for immigrants, who benefit from interactions with secular and ethno-religious groups. Our findings confirm previous cross-national research, but they also highlight the need to elaborate the relationship between institutional context and ethnically specific reproduction mechanisms within countries.     

Chapter 2

No abstract available for this article.     

Classroom homogeneity and the distribution of student math performance: A country-level fixed-effects analysis

Is the homogenous grouping of students by ability conducive to learning for all students alike, or does it affect students of different ability levels differently? To address this question, I compare the distributions of math performance for students between Grade 8 and Grade 4 across countries with different levels of between-classroom ability grouping, controlling for country-level unobserved heterogeneity using a fixed-effects model. Homogeneous grouping, relative to heterogeneous grouping, is found to have no significant impact on mean performance, but it does increase performance inequality by benefiting the high achievers at the expense of the low achievers.     

Effects of ability mixing in high school on adulthood earnings: quasiexperimental evidence from South Korea

We estimate impacts of ability mixing compared to ability grouping in high school education on students’ adulthood earnings. To overcome endogeneity and selection problems that plagued the previous studies, we exploit a policy experiment in South Korea in the 1970s, which changed the education regime of general high schools from grouping to mixing in major cities. We find that the mixing treatment has a positive but statistically insignificant effect on average adulthood earnings. We also find that while mixing has positive effects on low ability students’ adulthood earnings, it has smaller positive or even negative effects on higher ability students.