Stability and Segregation in Group Formation

This paper presents a model of group formation based on the assumption that individuals prefer to associate with people similar to them. It is shown that, in general, if the number of groups that can be formed is bounded, then a stable partition of the society into groups may not exist. (A partition is defined as stable if none of the individuals would prefer be in a different group than the one he is in.) However, if individuals' characteristics are one-dimensional, then a stable partition always exists. We give sufficient conditions for stable partitions to be segregating (in the sense that, for example, low-characteristic individuals are in one group and high-characteristic ones are in another) and Pareto efficient. In addition, we propose a dynamic model of individual myopic behavior describing the evolution of group formation to an eventual stable, segregating, and Pareto efficient partition. Journal of Economic Literature Classification Numbers: C72, H41.     

绿色中药产业初见成效 发展任重道远——对汉中市部分中药产业重点发展县的调查

近年来,汉中市实施＂发展绿色产业,建设绿色汉中＂的战略,中药产业逐渐成为汉中经济发展新的增长极。为了解汉中中药产业的发展情况以及银行业机构金融服务支持情况,笔者先后深入勉县、留坝、佛坪等中药材生产形成一定规模的县域,采取与当地政府部门、银行业机构座谈,深入农户中药材种植基地和实地察看加工企业等方式进行了专题调研,分析了其中问题并提出相关建议。     

An algebraic theory of portfolio allocation

Summary. Using group and majorization theory, we explore what can be established about allocation of funds among assets when asymmetries in the returns vector are carefully controlled. The key insight is that preferences over allocations can be partially ordered via majorized convex hulls that have been generated by a permutation group. Group transitivity suffices to ensure complete portfolio diversification. Point-wise stabilizer subgroups admit sectoral separability in fund allocations. We also bound the admissible allocation vector by a set of linear constraints the coefficients of which are determined by group operations on location and scale asymmetries in the rate of returns vector. For a distribution that is symmetric under a reflection group, the linear constraints may be further strengthened whenever there exists an hyperplane that separates convex sets. Received: May 15, 2001; revised version: March 20, 2002 RID="*" ID="*" Journal paper No. J-19797 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 3463, and supported by Hatch Act and State of Iowa funds. Correspondence to: D. A. Hennessy     

Entrepreneurs in the making: Six decisions for fostering entrepreneurship through maker spaces

Maker spaces—shared production facilities offering access to basic and advanced manufacturing technologies—have quickly become the latest must-have for universities, large corporations, and communities looking to foster entrepreneurship and innovation. While the entrepreneurial and educational prospects of maker spaces are certainly intriguing, questions remain concerning their design and effectiveness. Drawing primarily on case evidence and conversations with five maker spaces located across the U.S., we identify and present six key decisions for maker space leaders looking to foster entrepreneurship in their organizations. We conclude with a decision framework for maker space leaders and a series of questions for entrepreneurs as both groups work to pursue entrepreneurship through and in maker spaces.     

非正式制度影响风险投资决策的机制研究——基于预期假说

投资者保守的思想一直是抑制我国风险投资发展的重要因素。本文研究了非正式制度、预期、决策和风险投资发展之间的关系,分析了我国非正式制度通过预期行为影响风险投资决策从而影响我国风险投资业发展的路径,最后以本文的结论对我国现存问题的原因做出了解释。     

医养结合养老综合体项目成功落地的经验启示

东北三省是国内人口老龄化问题最为突出的地区,目前,低生育率与人口老龄化仍在不断加剧.据吉林省“六普”数据显示,60岁及以上老年人口达15.21％,0-14岁少儿占10.24％,劳动年龄人口占74.55％,人口年龄中位数为38.27岁.这些数字说明,吉林省正进入老年型人口社会.面对老龄化发展趋势和老年人口增多等因素,金融...     

The take-up of business support by minority ethnic enterprises: The experience of South Asian businesses in England

This research contributes to a greater understanding of minority ethnic business (MEB) needs and practices and helps identify the support needs of minority ethnic firms in relation to existing support provision. The aims are, therefore, to examine the take-up of support by minority ethnic enterprises focusing mainly on the South Asian community with some representation from the African-Caribbean and Korean communities. Fifty minority ethnic businesses across South West London were contacted and semi-structured interviews took place with the owner/owner managers. The findings suggest that policy makers need to appreciate the diversity of MEBs and policies aimed at these businesses should reflect that diversity.     

内支撑支护在深基坑工程中的应用

本文结合工程实例,详细阐述了深基坑工程采用排桩+锚索+内支撑复合支护技术的方案设计,并对施工降水、施工监测进行了深入的说明和总结,实践证明,该深基坑工程支护技术方案是成功的。     

基于投资效能的分配决策模型在工程建设投资决策中的应用

在基于投资效能最大化的基础上,对工程建设投资分配模型的建立进行了初步的分析,为提高投资分配的决策提供了科学依据。     

对少年儿童短道速度滑冰运动员的选材及科学训练

本文就如何选材及少儿短道速滑训练中平衡支撑能力、力量、柔韧性的训练方面做以详细的阐述。