Inverse Problems of Matroid Intersection

In this paper we study the inverse problem of matroid intersection: Two matroids M ₁ = (E, ₁) and M ₂ = (E, ₂), their intersection B, and a weight function w on E are given. We try to modify weight w, optimally and with bounds, such that B becomes a maximum weight intersection under the modified weight. It is shown in this paper that the problem can be formulated as a combinatorial linear program and can be further transformed into a minimum cost circulation problem. Hence it can be solved by strongly polynomial time algorithms. We also give a necessary and sufficient condition for the feasibility of the problem. Finally we extend the discussion to the version of the problem with Multiple Intersections.     

Hormesis: A Highly Generalizable and Reproducible Phenomenon With Important Implications for Risk Assessment

From a comprehensive search of the literature, the hormesis phenomenon was found to occur over a wide range of chemicals, taxonomic groups, and endpoints. By use of computer searches and extensive cross-referencing, nearly 3000 potentially relevant articles were identified. Evidence of chemical and radiation hormesis was judged to have occurred in approximately 1000 of these by use of a priori criteria. These criteria included study design features (e.g., number of doses, dose range), dose–response relationship, statistical analysis, and reproducibility of results. Numerous biological endpoints were assessed, with growth responses the most prevalent, followed by metabolic effects, reproductive responses, longevity, and cancer. Hormetic responses were generally observed to be of limited magnitude with an average maximum stimulation of 30 to 60 percent over that of the controls. This maximum usually occurred 4- to 5-fold below the NOAEL for a particular endpoint. The present analysis suggests that hormesis is a reproducible and generalizable biological phenomenon and is a fundamental component of many, if not most, dose–response relationships. The relatively infrequent observation of hormesis in the literature is believed to be due primarily to experimental design considerations, especially with respect to the number and range of doses and endpoint selection. Because of regulatory considerations, most toxicologic studies have been carried out at high doses above the low-dose region where the hormesis phenomenon occurs.     

企业获取成本竞争优势的价值链分析法

本文把价值链作为成本分析的系统框架和基本工具,描述了价值链及其组成部分,阐述了怎样使用成本驱动因素的概念和方法分析成本行为,指出了企业获取成本竞争优势的两种主要方法和我国企业成本管理的五大误区。     

委托─代理理论中自然状态的不确定性对最优契约影响的研究

本文考虑了委托─代理理论中代理人和委托人对于不确定的自然状态可能会有不同的概率,另外还考虑了自然状态对代理人努力负效用的影响,对委托─代理模型进行了拓展研究,使原有模型成为一个特例。通过一个简化的委托─代理框架进行分析,结果表明,代理人对自然状态的概率与代理人可能付出的努力水平有正相关关系,而且代理人和委托人对自然状态的概率对最优契约有不可忽视的影响。     

当代中国政治文化发展的成本及其投入

当代中国的政治文化发展,需要支付一定的成本。这些成本包括:保障成本、认同成本、规范成本、机会成本。这些成本在政治文化发展中的支付,要遵循合理性原则。应该谨慎判断发展成本付出的必要性,按认同成本———规范成本———机会成本———保障成本的顺序来投入;应注意政治文化发展成本付出操作的可行性,成本投入的层次应先低后高。应考虑发展成本效应的有利性,使民主和法治由发达地区向不发达地区逐步扩展。应重视政治文化发展成本支付的公平性,创造良好的政治文化环境,消除改革与发展中的成本分担不合理的现象。     

对"员工持股制度"的理性思考--从华为股权争论看员工持股制度

尽管员工持股制度在西方国家运行良好,但我国实施这一制度却并未达到预期效果.文章通过分析"华为"的股权争论,认为造成我国员工持股制度失效的原因是我国的员工持股制度在实施中存在管理不规范问题,员工持股制度本身存在难以克服的制度性缺陷及产生额外的交易费用和成本.所以对员工持股制度需要辩证认识,不能简单效仿.一味追求所谓的经济民主,可能得不偿失.     

点线面项目管理法研究

作为项目的组织管理者,时刻都要应对繁杂的项目内容,如何实施高效的项目管理模式是社会各界都在努力研究的课题。项目的失败犹如一个几何体的坍塌,项目的失败原因往往集中在以下三个方面:关键点出现问题;违背项目实施程序;决策界面和执行层面出现问题。基于此,提出点线面项目管理法。该方法的核心内容是:寻找项目实施过程中的关键点,并制定关键点的预控措施;建立项目实施过程中的程序控制线;强化项目实施过程中的决策界面和执行层面管理。     

航空公司战略联盟的经济动因分析

本文从经济学角度讨论航空公司战略联盟的动因,认为航空公司联盟旨在节约生产成本和交易成本。本文分析了航空公司战略联盟的网络经济性,基于交易成本经济学分析了航空公司联盟相对于市场而言对交易成本的节约。本文提出修正的威廉姆森启发式模型,并将其应用于分析和比较在国际航空运输市场中完整航空客运产品的实现方式。     

优化长株潭三市产业结构的对策研究

目前长株潭三市的产业结构存在着"同构化"、"低度化"、"低层次化"等诸多因素.加入WTO后,这些矛盾进一步存在将使长株潭三市经济面临更大的挑战,从而影响长株潭三市经济的发展,及时研究并确立相应的策略具有紧迫的现实意义.     

Experimental Design of Bioassays for Screening and Low Dose Extrapolation

Relatively high doses of chemicals generally are employed in animal bioassays to detect potential carcinogens with relatively small numbers of animals. The problem investigated here is the development of experimental designs which are effective for high to low dose extrapolation for tumor incidence as well as for screening (detecting) carcinogens. Several experimental designs are compared over a wide range of different dose response curves. Linear extrapolation is used below the experimental data range to establish an upper bound on carcinogenic risk at low doses. The goal is to find experimental designs which minimize the upper bound on low dose risk estimates (i.e., maximize the allowable dose for a given level of risk). The maximum tolerated dose (MTD) is employed for screening purposes. Among the designs investigated, experiments with doses at the MTD, 1/2 MTD, 1/4 MTD, and controls generally provide relatively good data for low dose extrapolation with relatively good power for detecting carcinogens. For this design, equal numbers of animals per dose level perform as well as unequal allocations.