优化股权结构:规范和完善上市公司治理结构的关键

本文首先提出公司治理的概念 ,并以此作为分析和研究的出发点 ,从现代企业理论和产权理论的角度 ,阐明了股权结构和股权流动安排与上市公司治理内部监控机制、激励机制和外部约束机制之间的关系 ,得出优化股权结构和股权流动安排是规范和完善上市公司治理的关键这一结论     

非拓扑孤子模型的相变特征与袋常数的温度依赖性

本文计算了在有限温度和密度下非拓扑孤子模型的有效势;得到了袋常数对温度和化学势的依赖关系;分析了禁闭解除相变的特征.结果表明:该模型的禁闭解除相变为一级;相变特征的分析表明有退禁闭相与禁闭相的两相共存.     

Weak disintegrability as a form of preservation of coherence

Summary Weak disintegrations are investigated from various points of view. Kolmogorov's definition of conditional probability is critically analysed, and it is noted how the notion of disintegrability plays some role in connecting Kolmogorov's definition with the one given in line with de Finetti's coherence principle. Conditions are given, on the domain of a prevision, implying the equivalence between weak disintegrability and conglomerability. Moreover, weak sintegrations are characterized in terms of coherence, in de Finetti's sense, of, a suitable function. This fact enables us to give, an interpretation of weak disintegrability as a form of “preservation of coherence”. The previous results are also applied to a hypothetical inferential problem. In particular, an inference is shown to be coherent, in the sense of Heath and Sudderth, if and only if a suitable function is coherent, in de Finetti's sense. Research partially supported by: M.U.R.S.T. 40% “Problemi di inferenza pura”.     

Potential exposures and risks from beryllium-containing products.

Beryllium is the strongest of the lightweight metals. Used primarily in military applications prior to the end of the Cold War, beryllium is finding new applications in many commercial products, including computers, telecommunication equipment, and consumer and automotive electronics. The use of beryllium in nondefense consumer applications is of concern because beryllium is toxic. Inhalation of beryllium dust or vapor causes a chronic lung disease in some individuals at concentrations as low as 0.01 microg/m3 in air. As beryllium enters wider commerce, it is prudent to ask what risks this might present to the general public and to workers downstream of the beryllium materials industry. We address this question by evaluating the potential for beryllium exposure from the manufacturing, use, recycle, and disposal of beryllium-containing products. Combining a market study with a qualitative exposure analysis, we determine which beryllium applications and life cycle phases have the largest exposure potential. Our analysis suggests that use and maintenance of the most common types of beryllium-containing products do not result in any obvious exposures of concern, and that maintenance activities result in greater exposures than product use. Product disposal has potential to present significant individual risks, but uncertainties concerning current and future routes of product disposal make it difficult to be definitive. Overall, additional exposure and dose-response data are needed to evaluate both the health significance of many exposure scenarios, and the adequacy of existing regulations to protect workers and the public. Although public exposures to beryllium and public awareness and concern regarding beryllium risks are currently low, beryllium risks have psychometric qualities that may lead to rapidly heightened public concern.     

Costs and Rewards of Children: The Effects of Becoming a Parent on Adults' Lives

How do new parents differ from their childless counterparts in social and psychological resources, daily strains, and psychological well‐being? Using a nationally representative panel of 1,933 adults who were childless at the first interview, we compare 6 indicators of adults' lives for those who became parents and those remaining childless several years later, controlling for earlier states. Becoming a parent is both detrimental and rewarding. With the exception of social integration, which is greater for all groups of new parents compared with their childless counterparts, the effects of parental status on adults' lives vary markedly by gender and marital status. Unmarried parents report lower self‐efficacy and higher depression than their childless counterparts. Married mothers' lives are marked by more housework and more marital conflict but less depression than their childless counterparts. Parental status has little influence on the lives of married men.     

Assessing accuracy of a continuous screening test in the presence of verification bias

Summary.  In studies to assess the accuracy of a screening test, often definitive disease assessment is too invasive or expensive to be ascertained on all the study subjects. Although it may be more ethical or cost effective to ascertain the true disease status with a higher rate in study subjects where the screening test or additional information is suggestive of disease, estimates of accuracy can be biased in a study with such a design. This bias is known as verification bias. Verification bias correction methods that accommodate screening tests with binary or ordinal responses have been developed; however, no verification bias correction methods exist for tests with continuous results. We propose and compare imputation and reweighting bias-corrected estimators of true and false positive rates, receiver operating characteristic curves and area under the receiver operating characteristic curve for continuous tests. Distribution theory and simulation studies are used to compare the proposed estimators with respect to bias, relative efficiency and robustness to model misspecification. The bias correction estimators proposed are applied to data from a study of screening tests for neonatal hearing loss.     

贸易开放、贸易增长与贸易平衡--对转型国家贸易发展的实证研究

本文对1992年到2002年中东欧和独联体25个转型国家贸易开放、贸易增长和贸易平衡问题进行实证研究.文章第一部分简单介绍了转型国家从经互会贸易体制到世界多边贸易体制的发展过程,并提出本文的研究目的、对象以及方法.第二部分用贸易开放、增长和平衡的分析指标对转型国家贸易发展情况作一概述,并引入贸易政策指标、宏观经济指标以及入世虚拟变量等解释因素.第三部分运用面板数据扩展模型(extended model)对转型国家贸易发展的不同作用因素进行统计检验并对结果做出相应分析.第四部分集中对两个转型国家集团-中东欧和独联体-贸易的不同发展状况及其决定因素进行统计检验和比较分析.     

Estimating rating transition probabilites with missing data

In this article we provide a rigorous treatment of one of the central statistical issues of credit risk management. GivenK-1 rating categories, the rating of a corporate bond over a certain horizon may either stay the same or change to one of the remainingK-2 categories; in addition, it is usually the case that the rating of some bonds is withdrawn during the time interval considered in the analysis. When estimating transition probabilities, we have thus to consider aK-th category, called withdrawal, which contains (partially) missing data. We show how maximum likelihood estimation can be performed in this setup; whereas in discrete time our solution gives rigorous support to a solution often used in applications, in continuous time the maximum likelihood estimator of the transition matrix computed by means of the EM algorithm represents a significant improvement over existing methods.     

On pooling data summaries in the absence of interactions “response-by-study”

The standard hypothesis testing procedure in meta-analysis (or multi-center clinical trials) in the absence of treatment-by-center interaction relies on approximating the null distribution of the standard test statistic by a standard normal distribution. For relatively small sample sizes, the standard procedure has been shown by various authors to have poor control of the type I error probability, leading to too many liberal decisions. In this article, two test procedures are proposed, which rely on thet—distribution as the reference distribution. A simulation study indicates that the proposed procedures attain significance levels closer to the nominal level compared with the standard procedure.     

论国际资本流动与金融危机的关系--兼析加入WTO后不断加剧的国际资本流动给我国带来的风险

20世纪90年代以来,各种类型的金融危机频繁爆发,对危机国乃至世界经济产生了巨大的影响。这些危机不但使国际学术界和各国政府都高度重视,而且也掀起了探索、研究金融危机的热潮。从国际资本流动的机制和国际资本流动的规模这两个角度,探析了国际资本流动与金融市场动荡和金融危机的关系,并分析了国际资本的充分流动,可能给加入WTO后的我国带来的风险与影响。