Scheduling Updates of Probabilistic Risk Assessments: The Arkansas Nuclear One-Unit 1 Experience

This paper presents the results of a study that identified how often a probabilistic risk assessment (PRA)should be updated to accommodate the changes that take place at nuclear power plants. Based on a 7-year analysis of design and procedural changes at one plant, we consider 5 years to be the maximum interval for updating PRAs. This conclusion is preliminary because it is based on the review of changes that occurred at a single plant, and it addresses only PRAs that involve a Level 1 analysis (i.e., a PRA including calculation of core damage frequency only). Nevertheless, this conclusion indicates that maintaining a useful PRA requires periodic updating efforts. However, the need for this periodic update stems only partly from the number of changes that can be expected to take place at nuclear power plants–changes that individually have only a moderate to minor impact on the PRA, but whose combined impact is substantial and necessitates a PRA update. Additionally, a comparison of two generations of PRAs performed about 5 years apart indicates that PRAs must be periodically updated to reflect the evolution of PRA methods. The most desirable updating interval depends on these two technical considerations as well as the cost of updating the PRA. (Cost considerations, however, were beyond the scope of this study.)     

具扩充Jacobi结点的Lagrange插值逼近

研究了以扩充Jacobi多项式(1+x)Vn(x)的零点为基点的Lagrange插值多项式Ln(f,x)逼近/k)的一些问题.     

马克思主义实践哲学在中国的早期传播

十月革命开创了世界历史的新纪元.从克利姆林宫传出来的马克思主义,对亚、非、拉人民是一个有力的号召.李大钊、陈独秀对马克思主义,特别是马克思主义哲学中的历史唯物主义给予高度重视和热情宣传,为马克思主义在中国的传播,为中国共产党的创建做出了巨大贡献.     

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.     

Assessing reoffense risk with juvenile sexual offenders

This article summarizes a two-year study of juvenile sexual offenders in Washington. Both community-based and institution-based treatment programs were evaluated. A typical profile of the juvenile sexual offender is offered, as well as recidivism data from a mean 20-month follow-up period.     

Farmers,the Practice of Farming and the Future of Agroforestry: An Application of Bourdieu's Concepts of Field and Habitus

Abstract Agroforestry, the practice of raising crops and trees together in ways that are mutually beneficial, provides farmers with an alternative to more conventional farming practices. In this paper, we apply Bourdieu's concepts of “field” and “habitus” in an attempt to better understand the practice of farming and the role that agroforestry may have in farming systems. Analysis is based on qualitative and quantitative interviews of farmers and other key informants in two regions, Fox‐Wyaconda Watershed in northeast Missouri and Scott County in southeast Missouri. Within the field of farming, farmers emphasized the importance of economic, family and rental relations. Important habitus considerations include different interpretations of what constitutes farming and what constitutes forestry. Based on Bourdieu's theoretical framework, we offer three alternative paths of social change that may lead to more widespread utilization of agroforestry.     

供应链管理模式下的企业外包设计研究

供应链管理是近年来在国内外逐渐受到重视的一种新的管理理念与模式,其管理思想是使企业将主要精力放在核心业务上,充分发挥优势,企业中的非核心业务外包给合作企业来完成。因此,企业外包设计成为供应链管理思想的一个重要方面。基于这一背景,首先探讨了企业外包的含义及其构成元素;并根据威廉姆森的新制度经济学中经济业务交易的规制结构对企业外包的规制层次进行划分;最后,构建了在供应链管理模式下基于交易成本和核心竞争力相结合的企业外包设计模型。     

The caring child: an evaluative case study of the Cornwall Young Carers project

This paper reports on an evaluation of the Cornwall Young Carers project (jointly funded by social services and the Cornwall and Isles of Scilly Health Action Zone), conducted during the period 2000–2002. A diverse range of methodological approaches were adopted (comparative national statistics, local pilot study, monthly and quarterly data capturing instruments, and a service user focus group) in monitoring and evaluating the project's high level statements/outcomes. Four evaluative themes are discussed, namely: identification of young carers; assessment of young carers' needs; direct service provision; and partnership working. Recommendations and action steps are proposed with a view of informing future planning and service delivery, as well as developing an ethos of integrating evaluation into everyday practice for the Cornwall Young Carers Project. Overall, the project has made significant progress in meeting and exceeding its original targets. The fact that the project has been able to identify 202 new young carers over this period is a key milestone in demonstrating the critical need for the project's services. It is suggested that existing referrals are only the ‘tip of the iceberg’ for work with young carers in Cornwall.     

匿名双向认证与密钥协商新协议

分析了一种新的匿名双向认证与密钥协商协议,它使移动网络向用户提供匿名服务, 访问网络与非法窃听者无法获知用户的身份信息,保证了用户身份、所在位置和行踪信息的机密性。该协议可以实现通信双方的相互认证,产生的会话密钥对通信双方是公正的。协议将双钥体制和单钥体制有机的结合起来,结构简单,安全高效。