Comparative Potency Method for Cancer Risk Assessment: Application to Diesel Particulate Emissions1

An estimation of the human lung cancer “unit risk” from diesel engine particulate emissions has been made using a comparative potency approach. This approach involves evaluating the tumorigenic and mutagenic potencies of the particulates from four diesel and one gasoline engine in relation to other combustion and pyrolysis products (coke oven, roofing tar, and cigarette smoke) that cause lung cancer in humans. The unit cancer risk is predicated on the linear nonthreshold extrapolation model and is the individual lifetime excess lung cancer risk from continuous exposure to 1 μg carcinogen per m³ inhaled air. The human lung cancer unit risks obtained from the epidemiologic data for coke oven workers, roofing tar applicators, and cigarette smokers were, respectively, 9.3 × 10^?4, 3.6 × 10^?4, and 2.2 × 10^?6 per μg particulate organics per m³ air. The comparative potencies of these three materials and the diesel and gasoline engine exhaust particulates (as organic extracts) were evaluated by in vivo tumorigenicity bioassays involving skin initiation and skin carcinogenicity in SENCAR mice and by the in vitro bioassays that proved suitable for this analysis: Ames Salmonella microsome bioassay, L5178Y mouse lymphoma cell mutagenesis bioassay, and sister chromatid exchange bioassay in Chinese hamster ovary cells. The relative potencies of the coke oven, roofing tar, and cigarette smoke emissions, as determined by the mouse skin initiation assay, were within a factor of 2 of those determined using the epidemiologic data. The relative potencies, from the in vitro bioassays as compared to the human data, were similar for coke oven and roofing tar, but for the cigarette smoke condensate the in vitro tests predicted a higher relative potency. The mouse skin initiation bioassay was used to determine the unit lung cancer risk for the most potent of the diesel emissions. Based on comparisons with coke oven, roofing tar, and cigarette smoke, the unit cancer risk averaged 4.4 × 10^?4. The unit lung cancer risks for the other, less potent motor-vehicle emissions were determined from their comparative potencies relative to the most potent diesel using three in vitro bioassays. There was a high correlation between the in vitro and in vivo bioassays in their responses to the engine exhaust particulate extracts. The unit lung cancer risk per μg particulates per m³ for the automotive diesel and gasoline exhaust particulates ranged from 0.20 × 10^?4 to 0.60 × 10^?4; that for the heavy-duty diesel engine was 0.02 × 10^?4. These unit risks provide the basis for a future assessment of human lung cancer risks when combined with human population exposure to automotive emissions.     

Decision Making Under Risk: A Comparison of Bayesian and Fuzzy Set Methods

A classical decision problem is considered where a decision maker is to choose one of a number of actions each offering different consequences. The outcome from a choice of action is uncertain because it depends on the existing state of Nature. Also, the outcome, once an action and state of Nature are specified, may be a vector or a random vector. The decision maker employs both Bayesian methods and fuzzy set techniques to handle the uncertainties. The decision maker is also allowed to use multiple, possibly conflicting, goals in order to determine his best strategy. The Bayesian method produces a set of undominated strategies to choose from, whereas the fuzzy set technique usually produces a unique optimal strategy.     

Contemporary Conceptions of Environmental Risk: Implications for Resource Management and Policy

Recent theoretical development in environmental sociology has focused on the concept of risk. Macro- and middle-range theoretical conceptualizations relevant to understanding environmental risk and resource depletion have emerged from Europe and the United States. We review five theoretical approaches to the environment–society relationship and identify convergent characteristics relevant for resource management in the modern world. These characteristics suggest goals for resource management should include expanded discursive systems, a more informed public and building institutional trust.     

Why Do They Start It? Explaining Reported Early-Teen Sexual Activity

This paper seeks an account of why young teens initiate consensual sexual activity. It does so by constructing statistical models aimed at distinguishing those who report having initiated sexual activity from those who have not in four samples of eighth graders from an Upstate New York county. Theoretical selection of the model variables is guided by insights from problem syndrome, control and differential association theories. From our findings we conclude the following: (1) Risk behaviors foreseen by the problem syndrome approach, including having used marijuana and having been drunk, are significant, powerful predictors of early-teen sexual activity. (2) The social setting of consensual sexual activity differs by sex at the eighth grade level. For example, having a boyfriend is a more consistent, powerful predictor variable for girls than is having a girlfriend for boys and there is evidence to support the hypothesis that boys initiate sexual activity in the context of status-seeking while girls are more likely to do so as a way of attaining approval. (3) Our findings do not give clear primacy to parents or peers as an influence on early-teen consensual sexual activity. Both control theory, usually associated with parental-influence variables, and differential association theory, usually associated with peer-influence variables, receive support. (4) The results of the research spanning a 2-year period of intensive community antiteen-pregnancy efforts by a Zero Adolescent Pregnancy (ZAP) campaign are consistent with the conclusion that such a multifaceted approach might help lower early-teen initiation of sexual activity.     

中国核电站供应链及其风险研究

基于核燃料和设备的核电站供应链体系是实现核电站连续生产运行的基本保障,因核电站生命周期较长,随着核电企业运行时间的延续,四大核电供应链面临的矛盾,以及核电站上游环节供应链的诸多变化,如供应商倒闭、供应商价格锁定、设备和备件更新换代无法实现直接维修更换等,带来了众多的核电站供应链的风险。核电站要建立一套完善的主动供应链风险管理流程,以识别、分析、定义和规避供应链风险,确保核电站连续高效、安全运行目标的实现。     

Why Study Risk Perception?

Studies of risk perception examine the opinions people express when they are asked, in various ways, to characterize and evaluate hazardous activities and technologies. This research aims to aid risk analysis and societal decision making by (i) improving methods for eliciting opinions about risk, (ii) providing a basis for understanding and anticipating public responses to hazards, and (iii) improving the communication of risk information among laypeople, technical experts, and policy makers.     

高校实验室档案的管理探讨

本文根据教育部规定提出了高校实验室档案管理的内容,并分析了当前高校实验室档案管理存在的问题,最后,提出了搞好高校实验室档案管理的一些措施。     

Merging data from multiple sources: pretest and shrinkage perspectives

In this article, we have developed asymptotic theory for the simultaneous estimation of the k means of arbitrary populations under the common mean hypothesis and further assuming that corresponding population variances are unknown and unequal. The unrestricted estimator, the Graybill-Deal-type restricted estimator, the preliminary test, and the Stein-type shrinkage estimators are suggested. A large sample test statistic is also proposed as a pretest for testing the common mean hypothesis. Under the sequence of local alternatives and squared error loss, we have compared the asymptotic properties of the estimators by means of asymptotic distributional quadratic bias and risk. Comprehensive Monte-Carlo simulation experiments were conducted to study the relative risk performance of the estimators with reference to the unrestricted estimator in finite samples. Two real-data examples are also furnished to illustrate the application of the suggested estimation strategies.     

中国商业银行效率：两种测度方法的比较

为了准确反映中国商业银行的效率水平,了解中国商业银行的效率现状,并对各商业银行之间、各类商业银行之间、中国商业银行与国际大银行之间的效率进行比较评价,有必要对中国商业银行效率进行准确的测度。分别从经济（财务）和技术（生产）的角度,采用财务指标分析法和数据包络分析DEA法来测度和评价中国商业银行的效率及排名,并对两种测度方法进行比较分析。     

中国P2P网络借贷信用风险的测量

分析中国P2P网络借贷信用风险的生成机理,借鉴商业银行典型个人信用风险测量理论基础与方法,构建基于涵盖借款人软信息的P2P网络借贷信用风险评级指标体系。通过向在银行从事信贷工作的专业人员发放调查问卷,确定具体指标,使用AHP(层次分析法)与DEMATEL(决策实验室法)相结合的方法综合确定指标体系权重,最后评级结果以百分制数值给出,并换算成具体的信用等级,有效解决了平台对借款人信用等级测量问题。