亚当·斯密的公路经济理论

研究了亚当.斯密公路经济理论的几个重要观点:公路的选址和规模、资金筹措、运营和征收车辆通行税等,并分析了车辆通行税管理权划归中央或地方的标准,得出建立监督机制、关注乡村公路和偏远公路有利于公路发展的结论,这对中国公路建设理论与实践有重要的借鉴作用。     

Defining the linear portion of a sigmoid‐shaped curve: bend points

Formulae are provided that define the ‘bend points’, the beginning and end of the essentially linear dose–response region, for the four‐parameter logistic model. The formulae are expressed in both response and dose units. The derivation of the formulae is shown in order to illustrate the general nature of the methodology. Examples are given that describe how the formulae may be used while planning and conducting bioassays. Copyright © 2003 John Wiley & Sons, Ltd.     

Exposure Reconstruction for the TCDD-Exposed NIOSH Cohort Using a Concentration- and Age-Dependent Model of Elimination

Recent studies demonstrating a concentration dependence of elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suggest that previous estimates of exposure for occupationally exposed cohorts may have underestimated actual exposure, resulting in a potential overestimate of the carcinogenic potency of TCDD in humans based on the mortality data for these cohorts. Using a database on U.S. chemical manufacturing workers potentially exposed to TCDD compiled by the National Institute for Occupational Safety and Health (NIOSH), we evaluated the impact of using a concentration- and age-dependent elimination model (CADM) (Aylward et al., 2005) on estimates of serum lipid area under the curve (AUC) for the NIOSH cohort. These data were used previously by Steenland et al. (2001) in combination with a first-order elimination model with an 8.7-year half-life to estimate cumulative serum lipid concentration (equivalent to AUC) for these workers for use in cancer dose-response assessment. Serum lipid TCDD measurements taken in 1988 for a subset of the cohort were combined with the NIOSH job exposure matrix and work histories to estimate dose rates per unit of exposure score. We evaluated the effect of choices in regression model (regression on untransformed vs. ln-transformed data and inclusion of a nonzero regression intercept) as well as the impact of choices of elimination models and parameters on estimated AUCs for the cohort. Central estimates for dose rate parameters derived from the serum-sampled subcohort were applied with the elimination models to time-specific exposure scores for the entire cohort to generate AUC estimates for all cohort members. Use of the CADM resulted in improved model fits to the serum sampling data compared to the first-order models. Dose rates varied by a factor of 50 among different combinations of elimination model, parameter sets, and regression models. Use of a CADM results in increases of up to five-fold in AUC estimates for the more highly exposed members of the cohort compared to estimates obtained using the first-order model with 8.7-year half-life. This degree of variation in the AUC estimates for this cohort would affect substantially the cancer potency estimates derived from the mortality data from this cohort. Such variability and uncertainty in the reconstructed serum lipid AUC estimates for this cohort, depending on elimination model, parameter set, and regression model, have not been described previously and are critical components in evaluating the dose-response data from the occupationally exposed populations.     

On the preservation of copula structure under truncation

The author characterizes the copula associated with the bivariate survival model of Clayton (1978) as the only absolutely continuous copula that is preserved under bivariate truncation.     

机械设计技能培训功能的教学模块

文章根据专业学习和技能培训的关系,设计了本科教学的机械设计技能培训模块,为培养大学生的设计技能提供了一个实践平台。     

Pathways between education and health: a causal modelling approach

Summary.  The association of poor education and poor health has been consistently observed in many studies and in various countries. Thus far, studies examining the mechanisms underlying this association have looked at only a limited set of potential pathways. This study simultaneously examines six distinctive pathways, which have been hypothesized to link education and health and found support from previous studies. A causal analysis of education and health was performed using structural equation models. Data were used from six phases of the National Child Development Study, which is based on following up an initial sample of 17416 children who were born in 1958. The association between education and health appears to be explained by a combination of mechanisms: adolescent health and adult health behaviours for men and women, adult social class among men and parental social class among women. We conclude that improvements in population educational attainment may not automatically lead to improvements in population health, and that health policies for improving health and reducing health inequalities need to target specific causal pathways.     

The government, the market, and the problem of catastrophic loss

This article addresses the comparative advantage of the government to the private property/casualty insurance industry for the provision of insurance coverage for catastrophic losses. That the government can play an important role as an insurer of societal losses has been a central public policy principle since at least the New Deal. In addition, our government typically automatically provides forms of specific relief following unusually severe or unexpected disasters, which itself can be viewed as a form of ex post insurance. This article argues that, for systemic reasons, the government is much less effective than the private property/casualty insurance market in providing coverage of losses generally, but especially of losses in contexts of catastrophes.     

Reclaiming the spirit: The journeys of gay men and lesbian women toward integration

The goal of this study is to understand and describe the way gay men and lesbian women see and interpret their spiritual journeys. Its intent is to open up the variety of experiences that gay men and lesbians encounter and is, therefore, not based on a single religious tradition or path, such as through crisis or AIDS. The findings included a model which interweaves the coming out process and the spiritual journey for this group of gay men and lesbian women, highlighting the period of questioning, reclaiming, and reintegration that happens for many as they resolve their sense of themselves as sexual and spiritual. Also addressed is the choice of mainstream and non-mainstream spiritual identification. The research discussed in this report was supported in part by the University Research Council, DePaul University.     

Sustainable societies in the information age

This article interweaves the ideas of sustainable development, sustainable societies, and the power of advanced information technologies toward developing recommendations for social science research on information technology in society. Worldwide concern has arisen over the potentially catastrophic consequences of global climate and environmental change. As a result, sustainable development (i.e., the simultaneous protection of both the global environment and the global economy) is receiving considerable attention. Necessary for achieving sustainable development are sustainable societies, which are capable of designing, implementing, managing and evaluating long-term environmental programs. This article presents ten characteristics that describe sustainable societies and discusses how information technologies, from wireless personal digital assistants to intelligent agents to multi-media database systems, could support the evolution of sustainable societies. Topics for social science research related to designing and ameliorating the negative consequences of eight hypothetical computer-based systems are presented. Bruce E. Tonn is leader of the policy systems analysis group at Oak Ridge National Laboratory and co-principal investigator of the National Center for Environmental Decision-making Research. His research interests include environmental and energy policy, computers in society, decision making, and futures studies. He is past president of the Social Science Computing Association. His research focuses on planning, assessment and evaluation, energy use and conservation, and education.