基于因果关系的教育研究方法思考

探索、检验因果关系是教育科学研究的重要目标之一,相关分析、回归分析、路径分析等常用统计方法存在许多不足。结构方程模型是针对这些不足提出来的,从统计思路上,它具有优点,但还不够完善,应引起我国教育学界的注意。     

我国现代远程高等教育发展若干问题研究

介绍了远程教育的现状，讨论了远程教育存在的问题，即主要问题是教学质量难以保证，提出了建立质量保证体系和集约化发展等相应措施。     

创新管理思维,引导我市课改实验的内涵性发展

教育管理思维决定着课程改革的组织形式、实验的有序开展和课程的内涵性发展。在课程改革中,教育管理思维的创新关系到三个方面:一是在理论探索的层面上,审视新时期人本主义教育思潮,接纳“以学生的发展为本”的时代观念;二是在实践操作的层面上,以优化课堂教学为中心,倡导自主、探究、合作的教学方式;三是为培养适应时代要求的教师队伍,促进专业发展,提高教师综合素质。     

论教育研究素质与教师专业成长

教育研究素质是现代教师素质结构的重要内容 ,是教师成为研究者的基础 ;教师的研究素质由理论素质、研究能力和研究道德素质三部分组成 ;教育研究素质在提高教师整体素质 ,促进教师专业成长中起着非常重要的作用     

企业改制与资产评估

企业改制是建立现代企业制度的必要途径。资产评估是企业改制中必不可少的重要环节。资产评估应明确评估目的、评估基准期、评估对象 ,掌握正确的评估方法和规范的评估程序。在企业改制中要特别注意设计稳妥的剥离方法 ,对非经营性资产和非经营性人员进行合理的剥离     

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.     

What to Do at Low Doses: A Bounding Approach for Economic Analysis

To quantify the health benefits of environmental policies, economists generally require estimates of the reduced probability of illness or death. For policies that reduce exposure to carcinogenic substances, these estimates traditionally have been obtained through the linear extrapolation of experimental dose-response data to low-exposure scenarios as described in the U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment (1986). In response to evolving scientific knowledge, EPA proposed revisions to the guidelines in 1996. Under the proposed revisions, dose-response relationships would not be estimated for carcinogens thought to exhibit nonlinear modes of action. Such a change in cancer-risk assessment methods and outputs will likely have serious consequences for how benefit-cost analyses of policies aimed at reducing cancer risks are conducted. Any tendency for reduced quantification of effects in environmental risk assessments, such as those contemplated in the revisions to EPA's cancer-risk assessment guidelines, impedes the ability of economic analysts to respond to increasing calls for benefit-cost analysis. This article examines the implications for benefit-cost analysis of carcinogenic exposures of the proposed changes to the 1986 Guidelines and proposes an approach for bounding dose-response relationships when no biologically based models are available. In spite of the more limited quantitative information provided in a carcinogen risk assessment under the proposed revisions to the guidelines, we argue that reasonable bounds on dose-response relationships can be estimated for low-level exposures to nonlinear carcinogens. This approach yields estimates of reduced illness for use in a benefit-cost analysis while incorporating evidence of nonlinearities in the dose-response relationship. As an illustration, the bounding approach is applied to the case of chloroform exposure.     

论西部大开发的主体与客体

本文提出西部大开发的主体是全国人民 ,客体为西部资源 ,并在此基础上探讨了西部教育资源开发观。     

教育旅游市场营销创新刍议

随着旅游需求个性化时代的到来,传统的把教育旅游等同于一般旅游的市场营销方式已经走到了尽头。因此,尽快实现教育旅游市场营销创新迫在眉睫。     

Dose-Response and Risk Assessment of Airborne Hexavalent Chromium and Lung Cancer Mortality

This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI).