Quantile regression and empirical likelihood for the analysis of longitudinal data with monotone missing responses due to dropout,with applications to quality of life measurements from clinical trials

The analysis of quality of life (QoL) data can be challenging due to the skewness of responses and the presence of missing data. In this paper, we propose a new weighted quantile regression method for estimating the conditional quantiles of QoL data with responses missing at random. The proposed method makes use of the correlation information within the same subject from an auxiliary mean regression model to enhance the estimation efficiency and takes into account of missing data mechanism. The asymptotic properties of the proposed estimator have been studied and simulations are also conducted to evaluate the performance of the proposed estimator. The proposed method has also been applied to the analysis of the QoL data from a clinical trial on early breast cancer, which motivated this study.     

Caution! Overestimation of treatment effects of corticosteroid therapy for community-acquired pneumonia in a meta-analysis of randomized controlled trials

It is well known that a meta-analysis of randomized controlled trials aims to increase the power and precision of the estimated intervention effects. However, when a meta-analysis includes a limited number of patients and a small number of events, overestimation of intervention effect estimates may occur and could cause spurious results. Although many biases can cause the overestimation, random error may be the most common cause. Trial sequential analysis (TSA) can explore the independent effect of random error on intervention effect estimates in meta-analyses and protect meta-analyses against overestimation due to random error.     

竹林区村庄白纹伊蚊孳生特点的调查

白纹伊蚊在竹林里孳生的阳性比为75.4%;而在竹林包围的居民区阳性比为15.3%。白纹伊蚊在居民区孳生密度布雷图指数为19.4,容器指数为6.2%。居民区孳生蚊虫的主要场所是泡菜坛,泡菜坛主要孳生蚊种是骚扰阿蚊,阳性比为73.7%,其次是淡色库蚊为20.2%,贪食库蚊为14.0%,白纹伊蚊最低,为9.1%。     

Optimal Selection of Sib Pairs from Random Samples for Linkage Analysis of a QTL Using the EDAC Test

Percentages of extremely concordant and extremely discordant sib pairs are calculated that maximize the power to detect a quantitative trait locus (QTL) under a variety of circumstances using the EDAC test. We assume a large fixed number of randomly sampled sib pairs, such as one would hope to find in the large twin registries, and limited resources to genotype a certain number of selected sib pairs. Our aim is to investigate whether optimal selection can be achieved when prior knowledge concerning the QTL gene action, QTL allele frequency, QTL effect size, and background (residual) sib correlation is limited or absent. To this end we calculate the best selection percentages for a large number of models, which differ in QTL gene action allele frequency, background correlation, and QTL effect size. By averaging these percentages over gene action, over allele frequency, over gene action, and over allele frequencies, we arrive at general recommendations concerning selection percentages. The soundness of these recommendations is subsequently in a number of test cases.     

Score Statistic to Test for Genetic Correlation for Proband-Family Design

In genetic epidemiological studies informative families are often oversampled to increase the power of a study. For a proband‐family design, where relatives of probands are sampled, we derive the score statistic to test for clustering of binary and quantitative traits within families due to genetic factors. The derived score statistic is robust to ascertainment scheme. We considered correlation due to unspecified genetic effects and/or due to sharing alleles identical by descent (IBD) at observed marker locations in a candidate region. A simulation study was carried out to study the distribution of the statistic under the null hypothesis in small data‐sets. To illustrate the score statistic, data from 33 families with type 2 diabetes mellitus (DM2) were analyzed. In addition to the binary outcome DM2 we also analyzed the quantitative outcome, body mass index (BMI). For both traits familial aggregation was highly significant. For DM2, also including IBD sharing at marker D3S3681 as a cause of correlation gave an even more significant result, which suggests the presence of a trait gene linked to this marker. We conclude that for the proband‐family design the score statistic is a powerful and robust tool for detecting clustering of outcomes.     

视场角设置对虚拟环境中目标判断的影响

目的探讨不同视场角参数对虚拟环境中目标判断的影响规律 ,找出最佳视场角参数。方法利用自行研制基于PC平台的虚拟现实 (VR)实验系统 ,选定 45名年龄在 2 3～ 5 8岁被试者并完成大小与角度判断的实验设计。首先进行 30 0人次的预实验 ,确定引起虚拟环境中目标判断差错的视场角及相应观察任务的差别等级 ,然后开始单因素、4水平的完全随机正式实验。结果方差分析表明 ,不同的虚拟环境视场角对目标判断的真实性有显著性影响 ,当视场角为 60°时 ,目标判断的正确率最大。结论利用VR技术进行载人航天器工效设计、操作训练或其它任务的研究时 ,应考虑视场角的作用 ,适合目标大小判断的视场角参数值宜取 60°,以便获得最大的工效     

沸石分子筛材料中次级孔的研究——Ⅱ.Y型沸石晶内次级孔对扩散的影响

以含有次级孔的沸石的晶内扩散为研究对象,对来源于同一NaY母体的一组改性Y型沸石,进行了孔结构分析和正戊烷的扩散系数的测定。得到了具不同次级孔量的Y型沸石晶内扩散性能变化的规律。并采用随机游动方法对实际的Y型沸石晶内扩散进行模拟,得到了与实验测定一致的结果,从而可以对有次级孔的Y型沸石的晶内扩散做定量的估计。     

The role of the nurse in active euthanasia and physician-assisted suicide

The researchers wanted to obtain insight into the cooperation between physicians and nurses with regard to active euthanasia and physician-assisted suicide (EAS). In study I a stratified random sample of 203 clinical specialists, 152 general practitioners (GPs) and 50 nursing home physicians (NHPs) participated. In study II a random sample of 521 GPs was drawn from the province of North Holland and a random sample of 521 GPs was drawn from the rest of the Netherlands. For study III all NHPs were approached. Data were collected by means of an interview in study I. In studies II and III an anonymous, postal questionnaire was used. Approximately half of the GPs did not consult with nurses about a patient's request for EAS, the intention to administer EAS, and the actual administration. In 5% of cases, the NHPs and the specialists did not consult with nurses concerning these aspects. The GPs and NHPs indicated in 4% and 3% of the cases, respectively, that nurses administered the lethal drug(s) to the patients; the corresponding figure for the specialists was 21%. Almost all GPs and NHPs and about three-quarters of the specialists thought that nurses should never be allowed to administer EAS.     

利用目的基因随机表位库筛选葡激酶抗原决定簇

目的：用目的基因随机表位库方法寻找葡激酶(straphylokinase SAK)的显性表位。方法：①SAK免疫BALB／C小鼠，免疫亲和层析纯化抗血清后，抗SAK抗体用生物素标记；②构建SAK随机表位肽库，随机挑取12个独立克隆测序，分析库DNA片段的分布和碱基含量情况；③以多抗为靶蛋白用克隆原位杂交法筛选肽库；④构建SAK的缺失突变体mSAK，Western blot分析mSAK的免疫反应性。结果：①筛选肽库得到一个由19个氨基酸组成的免疫显性表位区，命名为A1区；②mSAK不能与抗SAK多抗反应。结论：用简便、有效的方法筛选得到了SAK的一个表位A1区，初步确定A1区是SAK引起免疫反应的重要区域。     

在线考试系统设计

作为评价网络学习效果的一个环节，网上考试越来越被人们接受和认同。文章介绍了在线考试系统的功能和结构，并对该考试系统中所用到的关键技术进行了详细的介绍，包括系统的通用性和安全性、题库的建设和管理、随机组卷算法等。