Optimal pricing for group buying with network effects

In this paper, we analyze online group-pricing mechanisms for sellers and compare them with the option of selling only to individuals. We formulate the demand for group buying and individual buying (GB and IB, respectively) based on the utility a consumer attains from each environment considering two specific types of externalities unique to our problem. First, we assume that consumers receive positive “network effects” from GB, i.e., they obtain utility from shopping with others because of information exchange and collective support. Second, they encounter a negative externality of group buying because of inconvenience costs and delays in receiving the products. The two types of externalities lead to distorted demand, which in turn affects prices and profits. We analyze the optimal and equilibrium strategies for a seller operating in monopoly, duopoly, and multiple-firm competition. We derive the equilibrium strategies and show the existence of a Nash Equilibrium under competition of multiple firms. In addition, we show that positive network effects from group buying often outweigh the negative externalities arising from costs.     

计算机性能与异构计算

介绍了传统的高性能计算机的局限性和异构计算的基本原理;指出异构计算具有更高的计算资源利用率,计算任务的总体执行时间最短。     

公用事业特许经营的政府监管研究

特许经营制度是公用事业市场化的主要实现形式,政府监管是公用事业特许经营法治化的重要内容。公用事业特许经营监管的基础是实现监管权的统一与独立。应从实体和程序两个方面完善特许权授予的监管。建立科学合理的价格模型及周期性审查和调整是公用事业特许经营价格监管的核心。公用事业特许经营质量监管的主要内容是督促建立内部质量管理制度、制定可量化的标准及建立质量检验体系。政府监管应推动公用事业的网络化普及、排除歧视性及完善补偿机制,以确保特许经营项目履行普遍服务。此外,必须加强对公用事业特许经营政府监管的监管制度建设。     

学生网络伦理的热点问题研究

网络在给学生带来便利信息资源的同时,也带来很多严重的网络伦理问题。通过对小学、中学和大学学生网络伦理方面问题的调查,研究当前学生网络伦理的热点问题,分析问题成因并探求其解决对策,以规范学生的网络伦理道德行为,从而正确使用网络资源,促进网络健康发展。     

Exploring the Importance of Business Clockspeed as a Moderator for Determinants of Supplier Network Performance*

As the importance of supplier networks becomes increasingly recognized as a vital factor to company performance, researchers and practitioners alike are focusing their attention on this subject. The study's main objective is to test the specific hypotheses that effective use of Information Technology (IT) and the depth of company relationships with suppliers are directly related to Supplier Network (SN) performance, and that industry clockspeed moderates these relationships. A convenience sample of 135 manufacturing organizations was used to empirically test these hypotheses. Our results indicate that clockspeed does moderate the relationship between IT use effectiveness and supplier network performance. The same is true in the case of supplier relations depth, and hence, managers are encouraged to pay attention to the items comprising network performance as a determinant of supplier network performance.     

Globalization, the structure of the world economy and economic development

How does the structure of the world economy determine the gains from participation therein? In order to answer this question, we conduct a state of the art network analysis of international trade to map the structure of the international division of labor (IDL). We regress cross-national variation in economic growth on positional variation and mobility of countries within the IDL from 1965 to 2000. We find that the highest rates of economic growth occurred to countries in the middle of the IDL over the course of globalization. Second, we find that upper tier positions in the IDL are converging with each other, but diverging from the lower tier. This suggests that the mechanism underlying the rapid economic growth in intermediate positions was their uniquely high rates of upward mobility, in turn a function of their middling position. Taken together, these findings suggest that a country’s long-term economic development is conditioned by its position in the IDL.     

大学英语四、六级网络考试考场建设研究

大学英语四、六级网考项目开始于2007年,第一次四级网考试点工作实施于2008年12月。大学英语四、六级网考项目的建设目标,是提高大学英语四、六级考试的效度和考务管理效率。以2009年10月份的一次考试为例,描述CET-4大学英语网考考场内的硬件设置、环境设置、网考所需的软件、硬件配置和考试系统的操作流程,并且对网考中出现的问题进行剖析,有助于提出行之有效的改进方案。     

Neighborhood conditions and social network turnover among older adults

Increasing research highlights heterogeneity in patterns of social network change, with growing evidence that these patterns are shaped in part by social structure. The role of social and structural neighborhood conditions in the addition and loss of kin and non-kin network members, however, has not been fully considered. In this paper, we argue that the residential neighborhood context can either facilitate or prevent the turnover of core network relationships in later life – a period of the life course characterized by heightened reliance on network ties and vulnerability to neighborhood conditions. Using longitudinal data from the National Social Life, Health, and Aging Project linked with data from the American Community Survey, we find that higher levels of neighborhood concentrated disadvantage are associated with the loss of older adults’ kin and non-kin network members over time. Higher levels of perceived neighborhood social interaction, however, are associated with higher rates of adding non-kin network members and lower rates of adding kin network members over time. We suggest that neighborhood conditions, including older adults’ perceptions of neighborhood social life, represent an underexplored influence on kin and non-kin social network dynamics, which could have implications for access to social resources later in the life course.     

Measuring social dynamics in a massive multiplayer online game

Quantification of human group-behavior has so far defied an empirical, falsifiable approach. This is due to tremendous difficulties in data acquisition of social systems. Massive multiplayer online games (MMOG) provide a fascinating new way of observing hundreds of thousands of simultaneously socially interacting individuals engaged in virtual economic activities. We have compiled a data set consisting of practically all actions of all players over a period of 3 years from a MMOG played by 300,000 people. This large-scale data set of a socio-economic unit contains all social and economic data from a single and coherent source. Players have to generate a virtual income through economic activities to ‘survive’ and are typically engaged in a multitude of social activities offered within the game. Our analysis of high-frequency log files focuses on three types of social networks, and tests a series of social-dynamics hypotheses. In particular we study the structure and dynamics of friend-, enemy- and communication networks. We find striking differences in topological structure between positive (friend) and negative (enemy) tie networks. All networks confirm the recently observed phenomenon of network densification. We propose two approximate social laws in communication networks, the first expressing betweenness centrality as the inverse square of the overlap, the second relating communication strength to the cube of the overlap. These empirical laws provide strong quantitative evidence for the Weak ties hypothesis of Granovetter. Further, the analysis of triad significance profiles validates well-established assertions from social balance theory. We find overrepresentation (underrepresentation) of complete (incomplete) triads in networks of positive ties, and vice versa for networks of negative ties. Empirical transition probabilities between triad classes provide evidence for triadic closure with extraordinarily high precision. For the first time we provide empirical results for large-scale networks of negative social ties. Whenever possible we compare our findings with data from non-virtual human groups and provide further evidence that online game communities serve as a valid model for a wide class of human societies. With this setup we demonstrate the feasibility for establishing a ‘socio-economic laboratory’ which allows to operate at levels of precision approaching those of the natural sciences.All data used in this study is fully anonymized; the authors have the written consent to publish from the legal department of the Medical University of Vienna.     

英语教学中网络技术应用的研究

信息技术飞速发展向教育提出了挑战,教育要跟上科学和社会现代化发展的步伐,就必须加快教育的信息化。英语课堂教学中适时、适量地使用网络技术并以和谐的理念来辅助英语教学,将给我们的英语教学带来鲜活的力量。本文探讨了如何在信息时代,运用网络技术进行英语教学。