Nonparametric smoothing in the analysis of air pollution and respiratory illness

While most of epidemiology is observational, rather than experimental, the culture of epidemiology is still derived from agricultural experiments, rather than other observational fields, such as astronomy or economics. The mismatch is made greater as focus has turned to continue risk factors, multifactorial outcomes, and outcomes with large variation unexplainable by available risk factors. The analysis of such data is often viewed as hypothesis testing with statistical control replacing randomization. However, such approaches often test restricted forms of the hypothesis being investigated, such as the hypothesis of a linear association, when there is no prior empirical or theoretical reason to believe that if an association exists, it is linear. In combination with the large nonstochastic sources of error in such observational studies, this suggests the more flexible alternative of exploring the association. Conclusions on the possible causal nature of any discovered association will rest on the coherence and consistency of multiple studies. Nonparametric smoothing in general, and generalized additive models in particular, represent an attractive approach to such problems. This is illustrated using data examining the relationship between particulate air pollution and daily mortality in Birmingham, Alabama; between particulate air pollution, ozone, and SO₂ and daily hospital admissions for respiratory illness in Philadelphia; and between ozone and particulate air pollution and coughing episodes in children in six eastern U.S. cities. The results indicate that airborne particles and ozone are associated with adverse health outcomes at very low concentrations, and that there are likely no thresholds for these relationships.     

社区建设中的政府职能转变

中国城市社区建设是在政府主导和推动下进行的 ,政府培育社区与转变自身职能同步进行构成这种建设的显著特征。本文结合西安市新城社区建设的实际情况 ,分析了政府在社区建设中的主导作用及其依据 ;提出了目前政府转变职能及推进社区建设方面存在的问题 ,给出相应的解决建议 ;对政府与社区职责的划分及社区的行政化问题作了简要探讨     

由社会主体到自然主体——论宋代文人投身自然的几种表现形式

宋代文人投身自然 ,实质上是一种由社会主体向自然主体的角色转换 ,这种角色转换表现为 4个层面 :在行为上诗酒山林、随遇皆乐 ;在心理上“安于冲旷、不与众驱”;在思想上“无愧于中、无责于外”;在感情上“不以物喜、不以己悲”。这四个层面归结到一点 ,则是抒写山水 ,营造“心灵屋宇”。文人们在这些“心灵屋宇”中流泄的是真挚的情感 ,人生的顿悟和孤芳自赏的高洁品格     

浅谈函数与方程

本文辩证地讨论了函数与方程二者之间的联系与区别；函数思想与方程思想的相互渗透与转化。从而给我们提供了用方程思想解函数问题和用函数思想解方程问题的方便。     

试析19世纪末20世纪初德国外交政策转变的经济动因

19世纪末20世纪初,统一后的德国无论从经济发展还是社会变化都已发展为一个现代意义上的工业化国家,作为上层建筑的基础,它也必然会促使德国外交政策的转变。     

房地产企业留住人才的博弈分析

本文通过建立博弈矩阵模型,并利用线性规划理论进行分析,指出房地产企业在提高工资待遇吸引人才的同时,建立有效的动态激励机制才是留住人才的关键.     

The Transformation of Psychology in a Post-Apartheid South Africa: An Overview

Certain issues that are being debated in psychology in a post-apartheid South Africa are discussed, namely the development of professional organizations, indigenous healing and psychology, the psychometric movement, and forms of methodological inquiry. It is argued that South African psychology is striving to become more appropriate to the majority of its peoples, whether it be on the professional or research fronts. There is a desire to develop indigenous epistemologies and not to become excessively reliant on Euro-American epistemological traditions. Psychology is struggling to make mental health resources available to all South Africans.     

Physiologically Based Liver Modeling and Risk Assessment

Because of the inherent complexity of biological systems, there is often a choice between a number of apparently equally applicable physiologically based models to describe uptake and metabolism processes in toxicology or risk assessment. These models may fit the particular data sets of interest equally well, but may give quite different parameter estimates or predictions under different (extrapolated) conditions. Such competing models can be discriminated by a number of methods, including potential refutation by means of strategic experiments, and their ability to suitably incorporate all relevant physiological processes. For illustration, three currently used models for steady-state hepatic elimination--the venous equilibration model, the parallel tube model, and the distributed sinusoidal perfusion model--are reviewed and compared with particular reference to their application in the area of risk assessment. The ability of each of the models to describe and incorporate such physiological processes as protein binding, precursor-metabolite relations and hepatic zones of elimination, capillary recruitment, capillary heterogeneity, and intrahepatic shunting is discussed. Differences between the models in hepatic parameter estimation, extrapolation to different conditions, and interspecies scaling are discussed, and criteria for choosing one model over the others are presented. In this case, the distributed model provides the most general framework for describing physiological processes taking place in the liver, and has so far not been experimentally refuted, as have the other two models. These simpler models may, however, provide useful bounds on parameter estimates and on extrapolations and risk assessments.     

对偶线性规划问题性质探析

探讨对偶线性规划的原始问题与对偶问题的属性，阐述两者的区别和内在联系，用较简便的方法论证其重要性质，揭示可行解与目标函数、可行解与最优解的关系，指出线性规划问题最优解从约束条件较少的对偶问题寻求为另一较简便之方法。     

缓解我国就业压力的重要途径--再谈农村工业化

工业化包括农村工业化,片面的工业化和单向的农村———城市人口流动模式都不能解决农村剩余劳动力就业问题。为充分就业找到新途径,关键在于对传统农业的改造和加速农村工业化发展。