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.     

两种财产权的均衡--一种宪政隐喻的研究

在某种意义上,“公共财产神圣不可侵犯”的宪法宣言彰显了社会主义对资本主义的批判;“私有财产权不可侵犯”的神圣入宪隐喻了宪政的理性。私有财产权与公有财产权的均衡宪制是一种“社会能量守恒定律”的宪政隐喻。这两种基本财产权的均衡态势既有静态的平衡,也有动态的衡平,并展现为“一明两暗”的对立形态和以人为目的的终极关怀。由于这种均衡态势在各国宪法中展现的侧重点不同,而成为各国形成不同的宪政观念的重要原因之一,这便是宪政的隐喻所在。在三种不同模式的宪法中检讨这一隐喻,为当下解构、建构和创新中国的宪政理念与制度具有重大意义。     

古诗文名句训诂研究

古诗文名句流传甚广，人们对其部分的理解尚有不妥之处。本文择其十者作一辨析。     

系统科学在大型技术装备项目中的应用

本文论述了系统科学的理论和方法在大型技术装备项目管理中的应用和发展,着重介绍了项目规划的方案优选和项目管理组织体系、计划控制系统,质量控制系统、项目管理信息系统。从这个项目管理系统的总体看,随着加工的进展,系统内信息不断扩大和加深,形成生产管理信息回路,而且采用人-机结合的信息网络,为配合项目管理发挥了重要作用。     

丝绸之路艺术史纲(上)

丝绸之路艺术以多样的形态、丰赡的成果及相互交融的复杂关系,构成了迄今为止涵盖面最大、延续时间最长的人类艺术现象,具有建构丝绸之路艺术史的基础和依据。丝绸之路艺术史的建构,或许会触动世界艺术史的重写,将可能影响世界艺术史观,反思并重建世界艺术史的逻辑。在丝绸之路艺术史的建构中,分期断代是绕不开的课题,也是必须克服的难题。笔者尝试从长时期历史特征和阶段性特点着眼,将丝绸之路艺术历史划分为四个时期、七个阶段。文章首先探讨了丝绸之路艺术史撰写的基本问题,继而探赜丝绸之路艺术史第一时期,即丝绸之路艺术史前史,对丝绸之路艺术溯源。     

On the shrinkage of local linear curve estimators

Local linear curve estimators are typically constructed using a compactly supported kernel, which minimizes edge effects and (in the case of the Epanechnikov kernel) optimizes asymptotic performance in a mean square sense. The use of compactly supported kernels can produce numerical problems, however. A common remedy is ridging, which may be viewed as shrinkage of the local linear estimator towards the origin. In this paper we propose a general form of shrinkage, and suggest that, in practice, shrinkage be towards a proper curve estimator. For the latter we propose a local linear estimator based on an infinitely supported kernel. This approach is resistant against selection of too large a shrinkage parameter, which can impair performance when shrinkage is towards the origin. It also removes problems of numerical instability resulting from using a compactly supported kernel, and enjoys very good mean squared error properties.     

家国命运的象征映射——论抗战文学中的“女难民”书写

考察抗战文学各种文体,其中出现了大量对民族苦难的写实与表达,而对于女性在战争中苦难与境遇的表现体现得最为真实与丰富。在抗战各类纪实书写中集中出现的女难民,既是战争所带来的民族苦难的具像化身,其实也被作家有意建构成一个反侵略战争文化的明确符号,成为表征战争与和平价值取向的有力砝码。
     

初中生学业自我概念的发展趋势及学业成绩的影响:五次追踪研究

通过对308名初中生进行五次追踪研究来探讨其学业自我概念的发展趋势及学业成绩的影响。潜变量增长模型的分析结果发现：（1）初中生的学业自我概念呈现出线性递减的发展趋势。（2）在性别差异方面,男生的学业自我概念初始水平显著低于女生,且随着时间的推移,这种差异并没有发生显著变化。（3）在任何时间点上,初中生学业成绩对学业自我概念均具有显著的正向影响,且这种影响具有稳定性。     

“忠君”：荀子“忠”思想的内核与逻辑指归

忠,是中国传统政治思想的重要组成部分,是社会政治生活参与者的最高行为准则。在“忠”思想发展史上,荀子的理论贡献在于对先秦各派的“忠”思想进行了批判继承、综合改造,并以儒家思想为基本出发点,对“忠”做了新的界定,将其向着“忠君”的方向做出了理论上的诱导与压缩,使得原本内涵相当丰富的“忠”思想在荀子这里开始出现围绕“君”之事进行定向思考的倾向,从而促成了后世“忠君”文化的形成。尤其是荀子对法家思想的借鉴,使其“忠”思想超越了先秦儒家文化的理想主义色彩,获得了更强的现实政治意义。荀子的“忠”思想主体包含三个内容：忠信、忠顺、忠君,归结为一点就是引导人们去忠君。质言之,忠君为体,忠道为用,忠道是为了更好地忠君,是为荀子忠思想的最佳概括。     

任务型组织内部管理的新特征

在组织理论研究中,组织的内部管理历来是一个十分重要的话题。组织的目标、环境和内部诸要素的特点是决定组织内部管理状况的根本因素。任务型组织作为一种“新”的组织形式,呈现出与传统常规组织不同的特征,具体表现在内部分工、权力结构、综合协调、成员合作等诸多方面。这些特征使任务型组织获得更强的适应性和自我调适能力,能够更好地应对环境的挑战,同时,也为组织管理理论和管理实践注入了新的内涵。对这些特征的探讨将使我们进一步加深对任务型组织的认识,使其在发展过程中不断完善。