Influence of human immunodeficiency virus infection on neurological impairment: an analysis of longitudinal binary data with informative drop-out

A study to investigate the human immunodeficiency virus (HIV) status on the course of neurological impairment, conducted by the HIV Center at Columbia University, followed a cohort of HIV positive and negative gay men for 5 years and assessed the presence or absence of neurological impairment every 6 months. Almost half of the subjects dropped out before the end of the study for reasons that might have been related to the missing neurological data. We propose likelihood-based methods for analysing such binary longitudinal data under informative and non-informative drop-out. A transition model is assumed for the binary response, and several models for the drop-out processes are considered which are functions of the response variable (neurological impairment). The likelihood ratio test is used to compare models with informative and non-informative drop-out mechanisms. Using simulations, we investigate the percentage bias and mean-squared error (MSE) of the parameter estimates in the transition model under various assumptions for the drop-out. We find evidence for informative drop-out in the study, and we illustrate that the bias and MSE for the parameters of the transition model are not directly related to the observed drop-out or missing data rates. The effect of HIV status on the neurological impairment is found to be statistically significant under each of the models considered for the drop-out, although the regression coefficient may be biased in certain cases. The presence and relative magnitude of the bias depend on factors such as the probability of drop-out conditional on the presence of neurological impairment and the prevalence of neurological impairment in the population under study.     

工业经济效益指标体系的再思考

为了适应社会主义市场经济的发展,国家统计局会同财政部、国家经贸委等有关部门对原有我国工业经济效益指标体系进行了修改,制订了一套新的工业经济效益综合评价考核指标体系,包括７项指标：总资产贡献率、资本保值增值率、资产负债率、流动资产周转率、成本费用利润率...     

多源场的高斯定理及其应用

现行的电磁学对线电荷的能量公式、静电平衡条件都没有直接推导过.本文先提出多源场的高斯定理公式,然后进行推导,以供参考.     

Convective Filmwise Condensation of R-11 inside a Vertical Tube

Partial condensation of refrigerant R-11 was experimentally and theoretically studied. The test apparatus consisted of two concentric tubes, with the vapor flowing downward in the inner tube and the cooling water in the annular space in countercurrent direction. By using the available dimensionless correlation, the mean heat transfer coefficient of the cooling water was determined, and then the mean condensationheat transfer coefficient was calculated from the overall heat transfer coefficient.The model of a homogeneous two-phase mixture of liquid and vapor, and Prandtl's principle of analogy between the momentum and heat transfer were used to establish the type of the correlation. Adopting the methods of the gradually linear regression and F-level evidence testing, the present paper proposed the dimensionless correlation to predict the relationship among the mean Nusselt number, Prandtl number, Kutateladze number and the dimensionless tube length.     

浅论图书馆的书评工作

本文通过分析书评在图书馆工作中的作用,提出图书馆应该加强书评工作及书评活动的一些组织方法     

性爱与情感的灵魂——劳伦斯和他的散论

劳伦斯在文艺思想和创造方法上提出了介入性爱和情感及主观感受真实性的观点。他从这种艺术的观点出发主张要深入到男女的性、爱和血意识中去。本文介绍劳伦斯的《恋爱中的女人》、《查太莱夫人的情人》、《儿子与情人》等小说和《看我们如何漫游》、《不朽的散文选》、《失落的诗章》、《劳伦斯的爱情》等散文中的有关性、爱、情感等的文艺观点     

比喻分类管见

本文针对大中学教坛上把比喻分为明喻、暗喻、借喻的“三分说”分类提出不同看法;认为应分为两大类：常式比喻和变式比喻,并着重分析了 常式比喻与变式比喻之间的联系及其“变”的规律     

九峰山地区兽类研究

本文叙述了内蒙古九峰山地区兽类的种类、数量及分布情况,并且对在各种生境和不同季节其种类和数量的变化进行了详细分析.对一些种类的经济价值及如何保护和利用也做了说明.     

Generalized varying-coefficient single-index model

In this paper, the generalized varying-coefficient single-index model is discussed based on penalized likelihood. All the unknown functions are fitted by penalized spline. The estimates of the unknown parameters and the unknown coefficient functions are obtained and the estimation approach is rapid and computationally stable. Under some mild conditions, the consistency and the asymptotic normality of these resulting estimators are given. Two simulation studies are carried out to illustrate the performance of the estimates. An application of the model to the Hong Kong environmental data further demonstrates the potential of the proposed modelling procedures.