Sampling Strategies for Toxic Air Contaminants

Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.     

行业干中学、市场规模与市场结构——中国微观制造企业的实证研究

本文使用中国制造业微观企业1999至2007年的大样本数据,探讨干中学在市场规模扩张的过程中对市场结构动态变化的影响。研究发现,干中学有助于提高行业市场集中度的下限;其次,在较低的干中学行业中,随着市场规模的增加,行业会形成无序的片状的市场结构,行业集中度极度分散;然后,在动态的市场结构中,行业的干中学效应有助于缓解市场结构扩散,使行业市场结构的变动保持一种"粘性";最后,在很高的干中学行业中,行业的市场集中度会呈现U型的态势,当市场规模达到最佳市场规模后,行业的市场集中度开始上升,此时,内生的市场壁垒会催生行业的市场势力。     

投资组合的行业集中度与基金业绩研究

本文探讨了投资组合的行业集中度与基金业绩之间的关系。采用Kacperczyk等的方法测量各基金的投资组合在13个行业中的资产配置情况,我们发现基金投资组合的行业集中度与基金业绩之间存在显著的负向关系,这说明行业集中度更高的基金业绩落后于那些实行分散化投资的基金。最后,不同子样本期间的考察表明结论是稳健的。因此,我们建议基金经理人在执行更为集中的行业投资策略时,应该保持谨慎的态度。     

创新活动空间集聚及其驱动因素国外研究进展评述

对国外有关创新活动空间集聚的研究文献进行梳理,分析了现有研究取得的成就和存在的问题,对未来研究的几个待突破的方面进行了展望。     

The myth of price convergence under economic integration: A proposed explanation for the difference in food prices across European countries

Conventional globalization theory states that regional economic integration will precede price standardization across participating countries due to the increased buying power of large retail groups and parallel imports. The resulting price corridor should merely reflect differences in logistic costs and short-term, local competitive actions. Yet, this study uses panel data from 25 European countries to examine how hefty food and beverage price differentials between regions remained constant over the last decade. Income, store productivity, and market concentration all contribute to the explanation for regional price differences. These findings suggest that, contrary to straight-line globalization theory, large European retailers’ decisions can influence price convergence and maintain important price dispersion between economically integrated countries. We provide recommendations to enhance market integration.     

超大型平台并购初创企业的反垄断法规制研究

超大型平台并购初创企业可能具有反竞争效应,然而在芝加哥学派“假阳性错误”成本大于“假阴性错误”成本的理论观点以及反垄断监管困境的双重影响下,反垄断执法机构对其长期采取宽容的态度。但是芝加哥学派的错误成本理论在应用于超大型平台并购初创企业时存在局限性。频繁实施的初创企业并购非但不会导致超大型平台走向自毁,反将进一步巩固其市场支配地位、抬高市场进入壁垒。即便市场经历漫长期间之后最终完成了自我纠正,规制不足所造成的“假阴性错误”成本也会十分高昂,平台经济领域公平竞争、行业创新发展和消费者权益保护均会受到长期不利影响。因此,在秉持“包容审慎监管”原则的前提下适度加大监管力度,应当成为对超大型平台并购初创企业进行反垄断法规制的基本取向。基于这一取向,未来对超大型平台并购初创企业的反垄断法规制思路需要进行以下调整：以初创企业市值、用户规模、流量规模等补正并购的既有申报标准;确立契合平台经济特点的竞争损害分析框架;针对超大型平台并购初创企业的不同效应建立宽严相济的法律制度;赋予反垄断执法机构更加广泛的证据收集权,强化参与并购经营者的证明责任,并通过结合这二者的方式来化解反垄断执法机构获取监管信息上的...     

Predatory purchasing practices in global apparel supply chains and the employment relations squeeze in the Indian garment export industry

While the literature has long acknowledged worker rights abuses in global apparel supply chains, less attention has been paid to the recent worsening of certain decent work deficits and its causes, which this article links to predatory purchasing practices arising from growing power asymmetries. These practices, illustrated here by the garment export industry in India, exert downward pressure on wages and incite non‐standard forms of employment and greater verbal and physical abuse as productivity demands rise. They can be addressed through pricing mechanisms that cover the cost of decent work, appropriate State regulation and worker involvement.     

Risk and diversification of nonprofit revenue portfolios: Applying modern portfolio theory to nonprofit revenue management

This study uses modern portfolio theory (MPT) to estimate the risk of nonprofit revenue portfolios and examines to what degree the revenue concentration measure based on Herfindahl–Hirschman Index is associated with the portfolio risk measure based on MPT. The findings suggest that nonprofits with greater revenue concentration have lower revenue portfolio risk in the whole sample analysis. However, it is plausible that this result is dominated by organizations reliant on commercial income, which comprise over half of the sample. In fact, when examined separately, the relationship varies by an organization's primary funding structure. While higher revenue concentration is positively associated with portfolio risk for organizations relying on donations or those without a consistent primary funding source, it appears to associate with a lower portfolio risk for commercial organizations and those relying on government grants. This study reflects on the concept of diversification derived from portfolio theory and calls attention to a more nuanced approach to nonprofit revenue strategy.     

综析经济法的精髓

经济集中,是指经济权威组织管理参与经济活动的权力以及为实现上述经济权力而制定的制度和程序.经济民主,是指经济活动主体行使权利的自由以及为实现这些权利所设定的制度和程序.经济法的精髓是经济集中与经济民主的对立统一.这种对立统一关系,在经济领域表现为国家干预和市场调节的对立统一;在政治领域的动因和表现为国家机器职能的转变;在法学领域的动因和表现是"社会本位"法理念的兴起和传统法学理论的突破;在法律领域的表现是经济法这一法律部门的出现.     

北京市现代制造业的产业组织结构分析

北京现代制造业的发展已有4年时间,对其发展状况和存在问题有必要从不同角度做出一个基本判断。本文主要从产业组织学的角度分析北京现代制造业产业组织结构的现状,探讨其存在的问题,并提出优化北京现代制造业产业组织的对策与建议。