Prevention versus Treatment under Precautionary Regulation: A Case Study of Groundwater Contamination under Uncertainty

Policy discussions on agricultural pollution problems characterize prevention as more cost effective and precautionary than ex post treatment. We derive conditions under which treatment alone is more cost effective in situations involving multiple sources of emissions, multiple sites affected, and a commonly used precautionary approach to uncertainty. We also show that a greater degree of precaution can result in less reliance on prevention. An empirical case study indicates that treatment alone is the most cost-effective means of dealing with nitrate in most Maryland community water system wells. The use of leaching prevention measures is restricted to the most intensive poultry producing areas. The incremental cost of precaution is substantial.     

Modeling Conditional Yield Densities

Given the increasing interest in agricultural risk, many have sought improved methods to characterize conditional crop-yield densities. While most have postulated the Beta as a flexible alternative to the Normal, others have chosen nonparametric methods. Unfortunately, yield data tends not to be sufficiently abundant to invalidate many reasonable parametric models. This is problematic because conclusions from economic analyses, which require estimated conditional yield densities, tend not to be invariant to the modeling assumption. We propose a semiparametric estimator that, because of its theoretical properties and our simulation results, enables one to empirically proceed with a higher degree of confidence.     

Stochastic Technology, Risk Preferences, and Adoption of Site-Specific Technologies

A model of farmer decision making is developed to determine the extent to which uncertainties about soil fertility and weather affect the value of site-specific technologies (SSTs) using jointly estimated risk and technology parameters. Uncertainty can lead risk-averse farmers to apply more fertilizers and generate more pollution than in the certainty case. Ignoring uncertainty and risk aversion would overestimate the economic and environmental benefits of SSTs and underestimate the subsidy required to induce adoption. Accounting for uncertainties and risk preferences might explain the low observed adoption rates of SSTs. Improving the accuracy of SSTs would increase the incentives for adoption.     

Estimating Willingness to Pay for Improved Water Quality in the Presence of Item Nonresponse Bias

This article deals with the problem of item nonresponse in contingent valuation surveys using a payment-card method, by applying a grouped-data sample-selection estimation technique that is capable of imputing the missing values conditional upon a respondent's decision to answer a willingness-to-pay question. The advantage of the technique lies in its ability to utilize all of the information in the sample, permitting a more efficient estimation in the presence of item nonresponse bias. The major determinants of willingness to pay appear to be household income, number of children, education, perception of existing water quality, and identification with environmental issues.     

对《形状和位置公差》新标准的理解和应用

通过对《形状和位置公差》新、旧国际的对比，综述了新、旧标准间的不同之处、便于迅速了解和应用新标准。     

Price rigidities and institutional variations in markets with posted prices

Summary Standard laboratory posted-offer markets respond slowly and incompletely to demand shocks. In these one-sided markets, where sellers control the setting of prices, very little information is transmitted via the process of exchange. For this reason, traders have trouble distinguishing randomness in their own experience from changes in market fundamentals. This paper reports the results of twelve laboratory markets conducted to assess whether some common variants to standard posted-offer rules can correct the adjustment deficiences. Although discounting, multiple postings and excess demand information all improve performance, we find that response remains poor, and efficiencies low.Support for this research was provided by the National Science Foundation (SBR 9319842 and SBR 9320044), and the University of Virginia Bankard Fund. Data are archived at FTP address: fido.econlab.arizona.edu. We wish to thank Charles Plott and Shyam Sunder for useful comments on an earlier draft of this paper. The usual disclaimer applies.     

经济全球化时代的企业核心竞争力

随着经济全球化进程的加快，我国企业日益步入信息技术极速发展、技术升级日新月异、世界市场自由开放、各国竞争激烈残酷、机遇挑战同时并存的新环境。企业意欲在这样错综复杂的市场竞争中立于不败之地并谋求长期生存与稳步发展，就必须深刻认识到核心竞争力是其长期竞争优势的源泉，是其获得成功的关键要素。     

创新型企业组织形式的设计

创新型企业在组织构成上与传统企业有很大的不同，它是为了达到技术和产品创新的目的，在不同专业领域进行一定方式的分工和合作的一批高素质技术人员的集合。因此，在组织上，创新型企业就要不同于传统企业的直线职能式的组织结构。经研究，它应以项目组为组织的基本单元，建立矩阵式的组织结构，充分利用人力资源，灵活、快速地适应环境的变化。     

试论基于WEB的企业信息系统对电子商务运作平台的支持

电子商务的实质就是信息化,就是信息技术在社会生产中的应用,电子商务经过管理信息系统时代进入到了电子商务时代,其使用的技术也由单纯使用计算机技术转变为计算机、网络及通信技术的综合运用.基于WEB的企业信息系统对电子商务的支持表现在互联网提供了企业信息系统的硬件平台;企业内联网的技术和思想实现了企业之间的横向联系和信息共享;以B/S模式为核心的分布模式实现了用户端界面的统一.     

滨海新区研发与转化基地建设中的科技中介服务体系构建

国内外科技园区的发展实践证明,科技中介服务体系的建立与完善是研发与转化基地建设必不可少的重要基础和支撑。本文结合滨海新区的实际,对滨海新区研发与转化基地建设中的科技中介服务体系的目标定位、结构设计以及高效运行的保障措施进行了重点探讨。