最优组合证券投资方法研究

本文提出了证券投资效率概念,据此定义了最优组合证券,它比Ｍａｒｋｏｗｉｔｚ均值－方差模型的最优解更优,并分别在允许卖空和不允许卖空条件下给出最优组合的求法。     

非负定方差阵下的证券组合投资决策模型研究

在用于度量投资风险的方差阵为非负定时，本文建立并研究了允许卖空与不允许卖空情形下证券组合投资决策模型，同时给出了计算最优投资比例系数的方法。     

基于遗传算法的模糊证券组合投资模型

在不允许卖空的情况下,为了体现投资者对期望收益的满意度,以最小风险对应的最大方差系数为目标,期望临界收益率为约束,运用模糊优化的方法建立了证券组合投资模型,并采用遗传算法给出了模型的求解。     

卖空约束对组合投资效率影响的实证研究

选取封闭式基金作为投资对象,构建投资组合,研究了卖空约束对组合投资效率的影响。结论表明:(1)相对于不允许卖空的组合投资,允许卖空条件下组合投资的转移系数和信息率得到提高,alpha-TE有效边界得到扩张,同时也拓展了投资经理的投资空间;(2)投资业绩(信息率)提升得益于转移系数的提高,转移系数提高越多组合业绩提升越显著;(3)尤其对激进型投资经理来说,取消卖空约束对提高组合投资效率的作用更为显著。     

马可维兹模型有效边界分

本文通过计算10支股票的期望收益率、标准差、协方差矩阵和相关系数,用拉格朗日乘数法对马可维兹模型(MM模型)进行最优投资组合的选择与分析,分可以卖空和不可以卖空绘制MM模型的有效边界图,更好地确定投资对象及最优分配比例,以便实现收益最大、风险最小的目标。     

非负约束下证券组合的临界线

本文通过对建立非负约束下证券组合的临界线方程,给出了求解限制卖空时证券组合投资最优权重的一种方法,这种方法既可求解给定收益下的证券组合投资最优权重,又可求解给定风险条件下证券组合投资最优权重。     

中国股指期货推出后对股票市场的影响分析

本文2010年4月16日,中国首个股票指数期货在中国金融期货交易所上市交易,其的推出使得在中国只能单面做多的中国股票市场出现了改变。股指期货作为基础性风险管理工具,具有价格发现、套期保值的功能,它的推出填补了由于我国股票市场缺乏卖空和融券功能,市场缺乏针对系统性风险的管理手段这一空白,将改变证券市场缺乏规避系统性风险工具的现状。因此我们应该对股指期货推出后对中国股票市场的影响予以研究讨论,使投资者对股指期货有一个深刻的了解,使中国股票市场的机构投资者拥有资产配置和风险管理的全新选择;普通投资者,则拥有了投资手段,使价值投资理念更加深入人心。     

均值—级差型组合投资优化选择模型

本文给出基于历史收益率数据的均值－极差型组合投资优化选择模型,该模型采用收益的极差作为风险的尺度,可以通过求解线性规划获得最优投资组合方案,在惧益分布为正态分布时与均值－方差模型的解相似,避免了均值－方差模型求解二次规划问题（尤其在解决大规模的组合投资问题）的计算复杂性,本文还考虑了存在交易费用时的情形。     

股票卖空机制与企业研发投资

本文以2007-2014年中国上市公司为样本,基于中国融券卖空的自然实验环境,采用双重差分模型检验了股票卖空机制对企业研发投资的影响。结果发现:(1)股票卖空机制抑制了中国企业研发投资的增长;(2)股票卖空交易对企业研发投资的抑制效应在治理机制不完善的上市公司更加显著;(3)股票卖空机制是通过提高企业被收购的威胁,促使企业采取真实的盈余管理等作用渠道抑制了企业的研发投资;(4)允许卖空的上市公司更可能出现研发投资效率不足。     

不允许卖空的证券组合选择模型研究

本文在Ｍａｒｋｏｗｉｔｚ的均值－方差模型基础上提出了一种既能对投资比例向量优化又能对投资对象选择优化的证券组合选择模型,研究了模型的最优解以及模型中风险选择参数的确定问题,给出了求解模型的最优解的树型算法。     

To serve and promote science development via innovation

CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing.     

Tracing the origin and early radiation of birds——Paleornithologist ZHOU Zhonghe

With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants."     

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.     

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.     

Stern-Gerlach effect goes chiral

Prof. SUN Changpu from the CAS Institute of Theoretical Physics and coworkers from University of Basel in Switzerland have worked out a way --at least in theory --to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams and is similar to the famous Stern-Gerlach effect, whereby a beam of atoms passing through a magnetic field is split in two according to the atoms＇ spin states （Phys. Rev. Lett. 99 130403）.     

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.