Goodness‐of‐fit methods for matched case‐control studies

The authors propose graphical and numerical methods for checking the adequacy of the logistic regression model for matched case‐control data. Their approach is based on the cumulative sum of residuals over the covariate or linear predictor. Under the assumed model, the cumulative residual process converges weakly to a centered Gaussian limit whose distribution can be approximated via computer simulation. The observed cumulative residual pattern can then be compared both visually and analytically to a certain number of simulated realizations of the approximate limiting process under the null hypothesis. The proposed techniques allow one to check the functional form of each covariate, the logistic link function as well as the overall model adequacy. The authors assess the performance of the proposed methods through simulation studies and illustrate them using data from a cardiovascular study.     

接触式低温固定中样品内部传热过程的分析

建立了用于电子显微镜生物样品制备的接触式低温固定法中的传热过程模型,并求得了一维常物性条件下的精确解。讨论了样品内部冷却速率的一些变化规律及其与样品初始温度和固化温度的关系,为实际的低温固定操作提供了理论指导。     

文化资源的整合&海河文化带的建设

一、文物遗迹的保护开发与海河文化带的建设 人文历史景观是城市极具活力的视觉要素,是构成城市视觉形象的精神和灵魂.可以说,人文识别(与地缘识别相对的包括历史、文化、风俗、民族等人文状况的识别系统)是一个城市最持久、最具资源潜力和最有文化人类学意义的识别系统.人文历史景观最重要的要素是城市的文化遗迹,它们是城市发展历史形态在物质实体上的表现,是城市的一笔宝贵的文化遗产,是不可再生的文化资源.一棵古树、一座桥梁、一条小街、一座建筑物,都是城市历史发展的文化符号,是城市文化特色的生动体现,都在不经意间透露出城市发展的信息,烙上了时代前进的印迹.通过文物遗迹的保护与开发,可以丰富城市的文化内涵,提升城市形象,为城市创造财富.     

基于虚拟仪器的土壤水分测试系统开发

采用PCl-812PG数据采集卡,基于虚拟仪器技术,以Delphi作为平台开发了土壤含水量测试系统,对AZS -2土壤水分传感器的功能进行了扩展。标定结果及实际应用表明,此系统性能稳定,精度较高。     

“换词求雅”的修辞作用及衔接功能

“换词求雅”作为一种消极修辞手段,在避免重复、增加文章的文体色彩方面起到了积极的作用。不仅如此,作为一种衔接手段,“换词求雅”也在保证语篇的衔接与连贯上发挥着不可替代的作用。本文通过对这种辞手段的应用原则及分类方法的阐述,试图表明“换词求雅”并不是为了语言花哨的目的而存在的,无论从修辞还是语法意义角度上看,这一修辞方法的作用都是其他方法难以替代的。     

浅谈现代篮球持球突破技术及运展

对篮球运动持球突破技术的分类与结构,持球突破技术的运用方法和持球突破后应注意的要素进行分析。     

Individual irrationality and social welfare

Individual preferences inconsistent with personal welfare caused neither by ignorance nor by a positive consideration for the welfare of others are defined as (welfare) irrational. Sources of irrationality (rigid adherence to moral principles, excessive fear of danger, excessive tempetation of pleasure, revenge, inertia, faulty telescopic faculty, the fallacy of diminishing marginal utility of utility, etc.) are discussed. An evolutionary explanation of irrationality is suggested and some implications for individual decision and social policy indicated.I am grateful to two anonymous referees for comments.     

Cohort shifts in the timing of births in Ghana

A comparison of cohorts of ever-married Chanaian women suggests evidence of a fertility transition beginning among younger women and select subgroups. Ghana's crude birth rate declined from a high of 50/1000 population in 1970 to 38.8/1000 in 1985. To ascertain whether marital fertility is now being controlled through conscious attempts to lengthen birth intervals, World Fertility Survey data from 1979-80 on the timing of births among different birth cohorts were analyzed. It was hypothesized that, as a result of the influence of Western values that stress independence from parents and the introduction of compulsory education, cohorts of the mid-1950s and 1960s would be more likely to postpone childbearing, more active in the modern sector of the economy, and more accepting of modern contraceptive usage for birth spacing than women in the 1930-39, 1940-49, and 1950-59 cohorts. For the 1940-49 cohort, it took 10.8 months for 25% to have a birth following 1st marriage, 18.7 months for 50% to have a 1st birth, and 27.4 months for 75% to complete this step. By comparison, these figures for the 1955-64 birth cohort were 9.9, 16.7, and 20.5 months, respectively. The significantly shorter (p 0.01) interval between marriage and 1st birth found among younger women in part reflects rising age at marriage; mean age at 1st marriage was 17.9 years for the 1940 cohort and 21.6 years for the most recent cohort. After the birth of the 1st child, recent cohorts were more likely to wait longer for the 2nd birth. For women born in 1950-64, it took 21.8, 36.7, and 44.6 months for 25%, 50%, and 75%, respectively, to reach parity 2. This pattern of lengthened birth interval beyond the 1st birth was apparent at all parities in the youngest cohort and indicates increasing acceptance of contraception among those who have come of age during a period of rapid social change.