农业水价调整对解决华北平原水资源短缺的有效性分析

以河南省封丘县为研究区,应用模型推导与调查实证的方法探讨了华北平原农业水价政策的有效性。结果表明：目前技术水平下田间需水的价格弹性有限,价格信号对农户的灌溉决策行为影响微乎其微。农户水环境意识薄弱以及考虑粮食自足与极低的农户收入是影响农业水价改革及其政策有效性的主要制约因素。提出改变农业用水管理模式,适当抬高农业水价,促进农户节水意识提高;建立节水效益补偿机制,试行“两部制水价+ 返还”的水价政策,促进节水技术进步等对策。     

农业水价调整对解决华北平原水资源短缺的有效性分析——河南省封丘县农业水价调查分析

以河南省封丘县为研究区,应用模型推导与调查实证的方法探讨了华北平原农业水价政策的有效性.结果表明:目前技术水平下田间需水的价格弹性有限,价格信号对农户的灌溉决策行为影响微乎其微.农户水环境意识薄弱以及考虑粮食自足与极低的农户收入是影响农业水价改革及其政策有效性的主要制约因素.提出改变农业用水管理模式,适当抬高农业水价,促进农户节水意识提高;建立节水效益补偿机制,试行"两部制水价+返还"的水价政策,促进节水技术进步等对策.     

塔里木河流域未来农业水价调整的需求弹性效应分析

本文立足当前塔河流域的成本水价,基于流域主要节水技术成本投入,构建了流域农业节水水价;然后,利用已有研究资料和流域不同作物的水分生产函数,进一步构建了流域农业水价的需求效应模型;分析了未来塔河流域不同农业节水水价的节水效应。研究结果表明：①基于节水水价的未来农业水价的调整可大幅降低灌水量,提高节水效应;②流域水价弹性系数会由缺乏弹性变为富有弹性,这成为流域农业水价调整可行性的一个标志;③不同作物水价需求弹性效应差别很大,这使未来流域农业水价的需求效应分析事关流域粮食安全和用水户的水价承受力问题,成为未来塔河流域农业水价调整研究的重要相关研究内容。     

泾河流域水资源需求结构分析与调控策略

泾河流域生态环境脆弱，水土流失严重，同时水资源短缺这些都已成为其发展的障碍，因此有必要弄清流域目前水资源需求状况和存在的问题。水资源需求部门主要是农业需水、工业需水、城镇居民生活需水、农村居民生活需水、河流生态环境需水、林地需水和草地需水，分别属于生产需水、生活需水和生态环境需水。为表征不同部门需水的时空特征，计算了该区域2000年各县各类需水部门的需水量，并从水资源需求部门差异、空间差异和时间匹配三个方面进行分析。结果表明：①各县总需水量变化在1.57×10⁸m³～14×10⁸m³之间，流域单位面积需水量变化在145.11mm～728.98mm之间，基本趋势是由东南向西北逐渐减少; ②流域以生产需水和生态需水为主，生产需水以农作物需水为主，在2/3县区易出现生产与生态环境争水现象; ③农作物和林地，尤其是农作物亏缺水量大，目前的灌溉水平很难改变亏缺局面，势必影响二者经济效益和生态效益的发挥; ④农业结构性用水短缺格局相对突出。单位面积农作物需水量，最高值在泾阳县，为5 682 m³/hm²；最低值在定边县，为4 022 m³/hm²，由于事先设定大多数需水定额不随县(区)的改变而改变，因此该值与作物结构密切相关。本文根据上述研究结果，对该区域水资源的合理利用提出建议，要求重点加强植被结构与农作物结构的调整。     

中国工业用水需求价格弹性测算——基于联立方程模型

水生态文明建设下,工业用水价格的有效调控关系到水资源管理成效的质量。基于2003—2019年的省级年度面板数据,利用联立方程解决内生性问题,估算中国工业用水需求的价格弹性。研究发现：①三阶段回归结果估计所得工业用水需求的价格弹性为-2.329,验证了工业企业的用水需求对价格变化较为敏感,即工业水价上涨,工业企业的用水需求将会呈现更为显著的下降;②当前水价存在一定程度的扭曲,提升水价的杠杆作用可显著缓解工业用水需求的紧张度;③分区域回归结果表明,不同区域的工业用水价格弹性存在显著差异,总体上呈现“西部>东部>中部”的宏观空间分布格局;④进一步分析发现,产业结构不合理、经济发展水平因素与水价不成正比,需求量不能完全决定价格,水价难以正确反映水资源价值等问题,抑制了东、中部地区工业水价经济杠杆作用的发挥。本文可为中国工业水价政策制定和水资源管理机制改革提供参考依据。     

基于ELES模型的生活水价与城镇居民承受能力研究——以江苏省为例

为探讨不同收入水平城镇居民生活水价承受能力差异,以协调生活水价改革与居民承受能力的矛盾,本文采用经济计量分析方法检验了2000年-2007年江苏省城镇居民收入分配对居民生活水价承受能力的影响。研究结果表明:水费支出负担水平随可支配收入的提高而呈现出减轻的趋势;需水收入弹性随可支配收入水平的提高而增大;最低收入户各期的基本需水支出均没有得到满足,低收入户的生活用水基本需求支出处于警戒位置,中高收入户各期的基本需水支出均得到了满足。在此基础上,结合江苏省城镇居民收入分配、生活水价及居民承受能力的分析,认为不同收入水平城镇居民对生活水价承受能力之所以存在明显差异,主要是受到收入分配的影响;提出江苏省在制定水价政策及水价改革时必须正视这一差异,特别是在水价的连续性上调过程中,要协调好生活水价改革与城镇居民承受能力之间的关系。     

基于ELES模型的生活水价与城镇居民承受能力研究

为探讨不同收入水平城镇居民生活水价承受能力差异,以协调生活水价改革与居民承受能力的矛盾,本文采用经济计量分析方法检验了2000年-2007年江苏省城镇居民收入分配对居民生活水价承受能力的影响.研究结果表明:水费支出负担水平随可支配收入的提高而呈现出减轻的趋势;需水收入弹性随可支配收入水平的提高而增大;最低收入户各期的基本需水支出均没有得到满足,低收入户的生活用水基本需求支出处于警戒位置,中高收入户各期的基本需水支出均得到了满足.在此基础上,结合江苏省城镇居民收入分配、生活水价及居民承受能力的分析,认为不同收入水平城镇居民对生活水价承受能力之所以存在明显差异,主要是受到收入分配的影响;提出江苏省在制定水价政策及水价改革时必须正视这一差异,特别是在水价的连续性上调过程中,要协调好生活水价改革与城镇居民承受能力之问的关系.     

塔里木河中下游水资源机制探讨

通过对塔里木河下游某地区农业用水的水价弹性计算、成本效益分析和管理机制分析，指出价格机制对当地水资源的调节作用十分有限，而造成这一现象的主要原因是“政府失灵”。因此，加强政府干预、消除“政府失灵”是本地区面临的首要任务。同时，对本地区水价的制定提出了自己的意见。     

基于门限效应的灌溉水价与用水量关系——以河北省地下水灌区为例

河北省是中国重要的粮食生产基地,水资源极为短缺,地下水超采严重。本文依据2019年河北省地下水灌区620份问卷调研数据,采用“以电折水”方法计算现状水价,应用门限回归模型检验灌溉水价对灌溉用水量的门限效应,并采用双对数线性模型建立两阶段灌溉用水需求价格函数。研究表明：①2019年河北省地下水灌区现状灌溉水价偏低,为0.35元/m³,现状灌溉用水量比灌溉定额高61.01 m³/亩,说明水价有提升空间;②灌溉用水需求价格曲线拐点对应的水价门限值为0.33元/m³,低于拐点时弹性系数为-0.21,高于拐点时弹性系数为-0.69,说明第一阶段水价提高对节水的作用较弱,第二阶段水价提高对灌溉节水的激励效果显著;③灌溉定额对应的水价为0.67元/m³,当现状水价提升到定额水价时,与现状灌溉用水量相比,节水率为27.60%。本文建议采用灌溉定额管理制度,推行定额水价,以发挥灌溉水价对农业节水的杠杆作用,研究结论可为地下水灌区的农业水价综合改革提供理论依据。     

需求函数假设对供应链协作契约机制设计的影响分析

构建了由单一供应商与单一分销商组成的两级供应链，着重研究了不同需求函数的假设对供应链协作契约机制设计是否存在影响。分别研究了线性需求函数（Linear）与弹性需求函数假设下供应链契约设计的差异性，并利用价格折扣策略来设计供应链协作契约机制。研究结果表明在两种需求函数下供应链契约机制设计可得到一些共同结论，但还有一些结论则因需求函数不同而有所差异。     

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.     

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.     

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.     

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