置信区间枢轴量法之区间端点确定方法的R实现

本文讨论了当枢轴量服从X^2分布及F分布时,置信区间左右端点的确定方法,对传统方法相比,能够使得区间宽度最小,并使用R软件实现之。     

信息经济环境下基于分形的投资收益率统计分布研究

投资收益率的统计分布是证券投资组合、金融产品定价和风险管理的基础，因此是金融经济学的非常重要的问题。传统的金融经济学认为投资收益率服从正态分布。本文通过证券市场的实证分析得出，投资收益率不服从正态分布，具有分形结构，服从分形分布。     

贝叶斯预测模型的应用

贝叶斯预测模型是运用贝叶斯统计方法进行的一种预测，它与传统预测方法的不同之处在于利用了来源于经验和历史资料的先验信息。通过实证分析的方法，将贝叶斯预测模型与普通回归预测模型的预测结果进行比较，结果表明贝叶斯预测模型具有明显的优越性。     

贝叶斯预测模型的应用

贝叶斯预测模型是运用贝叶斯统计方法进行的一种预测,它与传统预测方法的不同之处在于利用了来源于经验和历史资料的先验信息。通过实证分析的方法,将贝叶斯预测模型与普通回归预测模型的预测结果进行比较,结果表明贝叶斯预测模型具有明显的优越性。     

注蒸汽井井筒温度分布简化模型研究

基于能量守恒原理,导出了描述稠油热采井井筒温度分布的数学模型,根据此模型可得到井筒温度分布的解析解,显示井筒温度分布服从指数函数变化规律。计算结果表明井筒温度分布曲线的形状取决于热流体注入量,反映了井筒内流动和传热特征。应用本模型可得到不同蒸汽注入量条件下的井筒温度分布曲线,计算方法简便快捷,方便工程应用。     

基于泊松分布和伽马分布的网络舆情热点发现

本文提出了一种基于泊松分布和伽马分布的网络舆情热点实时识别方法。该方法使用话题的人气和时间间隔特征两方面来识别舆情热点,发现单位时间内（如1小时）参与话题讨论的人数成泊松分布,回帖的时间间隔服从伽马分布。本研究用历史数据证明了该方法具有良好的识别效果。     

MIS软件寿命服从Weibull分布的可靠性分析

本文要介绍MIS软件开发过程中 ,通过截尾寿命测试所采集到的软件故障数据 ,应用可靠性统计的方法 ,对寿命服从Weibull分布的MIS软件 ,建立最大似然方程的参数迭代法 ,确定可靠性指标 ,并以实例计算验证。     

几种先验分布下指数分布参数的贝叶斯估计

运用贝叶斯决策方法,在定时和定数截尾寿命试验下,引入两种损失函数,总结和进一步推断指数寿命分布的分布参数取各种不同先验分布形式时的贝叶斯估计。     

单向分类模型误差方差齐性检验

文章重点介绍了方差齐性检验的4种方法,并指出,在对方差分析模型进行假设检验时,如果每个观测值的方差不相等,则方差分析的检验统计量一般不会服从F分布。     

粒子滤波算法理论在目标跟踪中的应用

粒子滤波算法是一种基于传播样本集的递归贝叶斯滤波器.本文中对粒子滤波算法原理以及在目标跟踪中的应用作了详细讨论,设计了目标模板更新方法.实验证明,粒子滤波跟踪算法具有很好的鲁棒性和抗遮挡、抗干扰性,但是计算量却很大.     

Students' Reactions to the Introduction of Videoconferencing for Classroom Instruction

This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors.     

Cooler temperatures inductive to locust outbreaks

Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007.     

Exploring Multiplexity: Social Network Structures in a Computer-Supported Distance Learning Class

A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction.     

The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong

Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies.     

Low doses of a red wine ingredient figh diabetes in mice

Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.     

How Electronic Publishers are Protecting Against Piracy: Doubts About Technical Systems of Protection

The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means.     

Rough Justice: A Statistical Assessment of ICANN's Uniform Dispute Resolution Policy

Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP.     

Prevalence of soft neurological signs in Chinese people

Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.     

Molecular motor assembly of a biomimetic system

Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction.     

Monoculture Rubber Plantations Have Negative Ef ects on Controlling Splash Erosion

<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence