Sampling Strategies for Toxic Air Contaminants

Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.     

基于Windows2000远程教育平台的开发和建设

近年来,随着计算机网络技术的飞速发展,国内外都在大力开发和推广基于internet的远程教育技术,这种教育系统以多媒体应用程序为基础,通过计算机网络将教师的图像,声音,作业传送给学生,通过实时或非实时来实现。本文介绍怎样利用Windows2000中的多媒体应用程序来搭建适合于远程教育的应用平台。     

计算机应用基础的教学改革

本文叙述了近年来《计算机应用基础》课程教学的改革过程。通过总结肯定已取得的成绩 ,同时找出仍存在的不足 ,努力改进 ,希望将今后的工作做得更好。     

认知交互CPI模型视角下新生就业压力及干预

面对严峻的就业形势,刚踏入高校校门尚且处于适应转换期的"95后"新生,俨然感受到了更大就业压力,压力认知交互作用理论认为压力对人是否产生影响,关键在于个体对压力的认知评价,认知评价影响到其采取的应对方式和应对结果,而应对结果反过来也影响压力的感知.根据压力认知-现象学-交互作用CPT模型,对高校"95后"新生就业压力进行分析,并寻求干预策略,为高校引导新生对就业压力的正确认知和积极应对提供借鉴.     

Win95工作站在局域网中的连结与应用探讨

本文以中文JWindows95 为例简要地介绍Win95 工作站在NOVELL 网、Win95 对等网、Windows NT 网三种典型局域网中的连结与应用.     

Parental spanking and subsequent risk for child aggression in father-involved families of young children

This study examined separate and combined maternal and paternal use of spanking with children at age 3 and children's subsequent aggressive behavior at age 5. The sample was derived from a birth cohort study and included families (n = 923) in which both parents lived with the child at age 3. In this sample, 44% of 3-year-olds were spanked 2 times or more in the past month by either parent or both parents. In separate analyses, being spanked more than twice in the prior month at age 3, by either mother or father, was associated with increased child aggression at 5 years. In combined analyses, there was a dose–response association; the greatest risk for child aggression was reported when both parents spanked more than twice in the prior month (adjusted odds ratio: 2.01; [confidence interval: 1.03–3.94]). Violence prevention initiatives should target and engage mothers and fathers in anticipatory guidance efforts aimed at increasing the use of effective and non-aggressive child discipline techniques and reducing the use of spanking.     

多板纲动物的不同保存方法对基因组DNA提取的影响

为了探讨最佳的适合提取DNA的石鳖样本保方法,以日本花棘石鳖Liolophura japonica、日本宽板石鳖Placiphorella japonica、红条毛肤石鳖Acanthochiton ruhrolineatus、平濑锦石鳖Onithochiton hirasei、网纹鬃毛石鳖Mopalia retifera为实验材料,对其分别以甲醛浸泡、95%乙醇浸泡、-75℃超低温保存的样本进行基因组DNA提取.通过紫外分光光度计、琼脂糖凝胶电泳对DNA产物进行检测.结果表明：新鲜材料和用乙醇保存的样品比用-75℃超低温保存的样品提取出的DNA纯度和浓度都高,用甲醛浸泡的方法保存没有提取出DNA.结果表明,超低温保存适合用于DNA提取.但是由于条件限制,长距离外采集样本时适合于用乙醇保存,并且成本较低.     

ADE-4: a multivariate analysis and graphical display software

We present ADE-4, a multivariate analysis and graphical display software. Multivariate analysis methods available in ADE-4 include usual one-table methods like principal component analysis and correspondence analysis, spatial data analysis methods (using a total variance decomposition into local and global components, analogous to Moran and Geary indices), discriminant analysis and within/between groups analyses, many linear regression methods including lowess and polynomial regression, multiple and PLS (partial least squares) regression and orthogonal regression (principal component regression), projection methods like principal component analysis on instrumental variables, canonical correspondence analysis and many other variants, coinertia analysis and the RLQ method, and several three-way table (k-table) analysis methods. Graphical display techniques include an automatic collection of elementary graphics corresponding to groups of rows or to columns in the data table, thus providing a very efficient way for automatic k-table graphics and geographical mapping options. A dynamic graphic module allows interactive operations like searching, zooming, selection of points, and display of data values on factor maps. The user interface is simple and homogeneous among all the programs; this contributes to making the use of ADE-4 very easy for non- specialists in statistics, data analysis or computer science.     

A Modified Knox Test of Space-Time Clustering

Tests of space-time clustering such as the Knox test are used by epidemiologists in the preliminary analysis of datasets where an infectious aetiology is suspected. The Knox test statistic is the number of cases close in both space and time to another case. The test statistic proposed here is the excess number of such cases over that expected under H₀ of no infection. It is argued that this modified test is more powerful than the Knox test, because the test statistic is not heavily tied as is the Knox test statistic. The use of the test is illustrated with examples.     

在校园网内建立内部局域网

本文叙述了如何用WINDOWS NT和WINDOWS 2000建立内部局域网来共享网上资源和INTERNET连接.