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).     

初中科学教育课程综合化的必然性及可行性研究

本文以世界范围内初中科学教育课发展趋势为主线,从科学教育课成的组成、结构、体系的角度,讨论了我国科学教育课程综合化的趋势,详细论证了我国初中科学教育课程综合化是历史的必然,同时对它的可行性做了探讨。     

20世纪中国文学思潮的演变及其反思--兼论中国现当代文学史分期问题

20世纪中国文学已经走完了它的全程 ,并完整地展现在我们的记忆与案头。纵览 2 0世纪中国社会思潮的发展进程 ,可以看出 :从“人文主义精神”到“社会主义思潮” ,再到世纪末“现代主义理念”的“生、住、异、灭”的嬗变演进 ,这些决定了 2 0世纪中国文学的整体走向 ,也使传统“现当代文学史”分期理论与编史叙述的本质缺陷清晰地暴露出来 ,从而有力地支撑着“2 0世纪中国文学”编史叙述的基本构想。     

Benchmark Analysis: Shopping with Proper Confidence

We discuss the issue of using benchmark doses for quantifying (excess) risk associated with exposure to environmental hazards. The paradigm of low-dose risk estimation in dose-response modeling is used as the primary application scenario. Emphasis is placed on making simultaneous inferences on benchmark doses when data are in the form of proportions, although the concepts translate easily to other forms of outcome data.     

论高校体育课程特色教材的构建

针对我国普通高校体育课程教材内容“千校一面”的实际，着眼于“学校教育要树立健康第一指导思想”观念的确立，以及学生对体育课程改革的期盼，构建适应新时代素质教育需要和符合高校自身专业特点与区域特色的体育教材。     

试论资产评估折旧与会计折旧的区别

文章针对部分资产评估人员在建筑物折旧问题上存在的错误认识和做法 ,通过分析建筑物折旧的原因和重置成本法评估中折旧的实质 ,从多方面详细比较论述了资产评估折旧与会计折旧的区别     

动物遗传育种系列课程双螺旋循环教学模式的建立与实践

根据动物遗传育种系列课程的结构、教学特点、本学科学生的层次性、学科发展和对教师多能性的要求 ,对该系列课程进行了教学内容、教学方式、教学手段的全面改革 ,构建了一套双螺旋循环教学模式 ,即教师与课程的螺旋循环链和学生层次与学习过程的螺旋循环链。这两条“教”、“学”互动的螺旋循环链有机结合 ,每完成一次循环教学过程 ,双螺旋上升一个螺距 ,教师的教学水平提高 ,学生的综合素质和学历提高一个层次。     

理想点法综合评价学生数学成绩

应用多目标决策———理想点法 ,建立了一个综合评价学生数学成绩的数学模型     

高新技术企业价值与企业生命周期

评估高新技术企业的价值要从其价值驱动因素入手,但高新技术企业在不同的生命周期阶段具有不同的价值驱动因素。因此,分析高新技术企业在生命周期各阶段的价值驱动因素以及相对应的价值评估方法,可以为高新技术企业的价值评估提供几点有益的启示。     

中职《建筑结构》课程改革初探

本文对《建筑结构》这一传统课程进行了剖析,提出了一些改革思路,特别对教学手段和方法提出了一些建设性建议。