IMPROVING POPULATION-SPECIFIC ALLELE FREQUENCY ESTIMATES BY ADAPTING SUPPLEMENTAL DATA: AN EMPIRICAL BAYES APPROACH

Estimation of the allele frequency at genetic markers is a key ingredient in biological and biomedical research, such as studies of human genetic variation or of the genetic etiology of heritable traits. As genetic data becomes increasingly available, investigators face a dilemma: when should data from other studies and population subgroups be pooled with the primary data? Pooling additional samples will generally reduce the variance of the frequency estimates; however, used inappropriately, pooled estimates can be severely biased due to population stratification. Because of this potential bias, most investigators avoid pooling, even for samples with the same ethnic background and residing on the same continent. Here, we propose an empirical Bayes approach for estimating allele frequencies of single nucleotide polymorphisms. This procedure adaptively incorporates genotypes from related samples, so that more similar samples have a greater influence on the estimates. In every example we have considered, our estimator achieves a mean squared error (MSE) that is smaller than either pooling or not, and sometimes substantially improves over both extremes. The bias introduced is small, as is shown by a simulation study that is carefully matched to a real data example. Our method is particularly useful when small groups of individuals are genotyped at a large number of markers, a situation we are likely to encounter in a genome-wide association study.     

Multiple-arm superiority and non-inferiority designs with various endpoints

Multiple-arm dose-response superiority trials are widely studied for continuous and binary endpoints, while non-inferiority designs have been studied recently in two-arm trials. In this paper, a unified asymptotic formulation of a sample size calculation for k-arm (k>0) trials with different endpoints (continuous, binary and survival endpoints) is derived for both superiority and non-inferiority designs. The proposed method covers the sample size calculation for single-arm and k-arm (k> or =2) designs with survival endpoints, which has not been covered in the statistic literature. A simple, closed form for power and sample size calculations is derived from a contrast test. Application examples are provided. The effect of the contrasts on the power is discussed, and a SAS program for sample size calculation is provided and ready to use.     

Physician/hospital business relationships. Sorting through the options

Providers recognize the critical role of physician/hospital partnerships in the newly emerging health care delivery system. However, the possibilities available for establishing such partnerships can be overwhelming. The authors provide a critical review of the options for physician/hospital business relationships. They emphasize the need to match physician/hospital strategies to local market characteristics, develop market-based business objectives, and structure physician/hospital relationships to support the achievement of business objectives.     

马克思主义文艺理论中国化若干问题的思考

关于马克思主义文艺理论中国化,本文作者对其过程曾做过一些思考,本文就是与此有关的几个思想断片的组合,涉及到的问题有:马克思主义文艺理论的普遍问题及其在中国的特殊问题是什么?两者的结合有什么特点,产生了怎样的结果?为什么说《在延安文艺座谈会上的讲话》是其标志和典范?《在延安文艺座谈会上的讲话》之后它又走过了怎样的路?     

论蒙古族游牧经济及其基本矛盾

蒙古族是典型的游牧民族之一。蒙古族游牧经济的内涵,是在农业文明时期,通过畜牧业生产方式而体现的蒙古族牧民劳动者素质技能的提高;蒙古族游牧经济的外延,包括种类上的“五畜”和时空上的界定。时间自蒙古民族形成到清朝末期,空间以蒙古高原为轴心地区。蒙古族游牧经济的基本矛盾是人与人之间的经济利益的矛盾。     

请名人做教父教母

像许多骄傲的父母一样,英国流行乐坛天王埃尔顿·约翰决定为儿子扎卡里选一位教母。他会选谁呢？当然是Lady Gaga了——她有钱、有名、有影响力。其实,在做父亲之前,埃尔顿就热衷于当别人的教父。他有10个教子（包括球星贝克汉姆的两个儿子布鲁克林和罗密欧,以及女明星戴米安·赫莉的儿子戴米安）,将共同继承他数百万英镑的遗产。幸运的是,载米安·赫莉的儿子还有其他教父母可以依靠,包括大明星休·格兰特、社会名流亨利·登特-布罗克赫斯特,以及女演员帕齐·肯西特。     

战略经济合作：增进美中关系

假如中国成为一个全球大国,那美国应如何应对？这是下一任美国总统所面临的一个严峻挑战。部分美国人认为,中国是美国未来的威胁,美国必须遏制中国经济的发展;另一部分美国人则认为,中国经济的增长对美国是利大于弊,美国应当增进与中国的经济合作。笔者认为,美中经济合作才是符合两国利益的明智之举。     

An evaluation of population projection errors for census tracts

"In this article we evaluate the accuracy and bias of projections of total population and population by age group for census tracts in three counties in Florida. We use [U.S. census] data from 1970 and 1980 and several simple extrapolation techniques to produce projections for 1990; we then compare these projections with 1990 census counts and evaluate the differences. For the total sample, we find mean absolute errors of 17%-20% for the three most accurate techniques for projecting total population and find no indication of overall bias. For individual age groups, mean absolute errors range from 20%-29%." This is a revised version of a paper presented at the 1993 Annual Meeting of the Population Association of America.     

种族隔离结束后的南非城市能否迈向交通便利、平等和可持续发展?

历史上城镇多建在水陆交通便利处。可惜城市普遍具有的这种宏观便利并未扩展到微观层面。本文认为 ,所谓交通可持续性 ,即可持续发展的城市向所有人提供去往不同目的地的手段 ,最好是低速移动或公共交通。私人小汽车的使用受到限制 ,没有交通堵塞 ,对噪音污染采取措施。从这个角度看 ,城市内便利通常很成问题 ,主要原因是交通规划与城市规划相分离。这一普遍模式在南非也存在 ,其原因当然是城市地区的不可持续性 ,而过去种族隔离的历史无异于雪上加霜。本文以开普敦为例 ,深入探讨这一问题。作者阐述了城市空间理论 ,例举了在一定程度上遵循这一理论的城市 ,为南非城市的建设提供参考。然而 ,欧洲的经验表明 ,仅有城市规划还不够 ,哪怕城市规划遵循的是一些成功的理论 ,如走廊型城市或整体型城市。城市规划应与交通规划相结合。南非应考虑实行整合城市与交通规划的政策 ,使城市变得更平等和可持续