On the use of surrogate end points in randomized trials

In a recent paper Day and Duffy proposed a strategy for designing a randomized trial of different breast cancer screening schedules. Their strategy was based on the use of predictors of mortality determined by patients' factors at diagnosis as surrogates for true mortality. On the basis of the Prentice criterion for validity of a surrogate end point, and data from earlier studies of breast cancer case survival, they showed that, not only would the trial require a much shorter follow-up, but also that the information (i.e. inverse variance) for evaluating a treatment effect on mortality would be greater by a factor of nearly 3 if the predictors of mortality were used, compared with a trial in which mortality was actually observed. Although these results are technically correct, we believe that the conceptual strategy on which they are based is flawed, and that the fundamental problem is the Prentice criterion itself. In this paper the technical issues are discussed in detail, and an alternative structure for evaluating the validity of surrogate end points is proposed.     

Exact percentage points for the Kolmogorov test on truncated versions of known continuous distributions with unknown truncation parameters

In this paper we deal with Kolmogorov-Smirnov testson uniformity with completely or partly unknown limits. Tables of exact percentage points are presented or referred using the wellknown determinant formula given by Steck (1971). It is shown that these tables also give the percentage points for the analogous statistics of the test on truncated versions of known continuous distributions with completely or partly unknown truncation limits. We will give some examples of these applications. Among these are the tests on exponentiality and on Pareto distribution with known shape parameter and unknown lower terminal.     

Testing for variance changes in autoregressive models with unknown order

The problem of change point in autoregressive process is studied in this article. We propose a Bayesian information criterion-iterated cumulative sums of squares algorithm to detect the variance changes in an autoregressive series with unknown order. Simulation results and two examples are presented, where it is shown to have good performances when the sample size is relatively small.     

新中国成立后毛泽东统一战线思想的主要内容及其特点

新中国成立后,毛泽东的统一战线思想在和平赎买、两个联盟以及多党合作和和平解决台湾问题等方面得到丰富和发展。其突出的特征即是鲜明的时代性和革命性、强烈的务实性和灵活性、巨大的开拓性和创新性。正确认识和把握这些内容及其特点,对于人们客观、理性地认识改革开放30年来党的统一战线理论和特点,并进行两者的比较具有一定的积极作用。     

大跨度粘土公路隧道台阶法施工技术探讨

在寒区大跨度浅埋粘土隧道施工中,因粘土含水量大、粘结力差、受施工扰动强度易衰减快,地基承载力低,施工方式选择不当易造成隧道坍塌．结合在建天恒山隧道大里程段台阶法施工的实践,对大跨度浅埋土质隧道采用台阶法施工中的开挖支护施工工艺、施工质量控制要点等进行分析和探讨,指导了天恒山隧道的施工．天恒山浅埋粘土隧道三台阶法施工的成功应用为大跨度浅埋土质隧道的施工提供了技术资料,可供同类隧道施工借鉴．     

通信技术专业实训基地建设中通信业务知识的渗透

在通信技术专业教学中,如何将通信工程中全业务知识和全程全网概念渗透给学生,使学生在真实的通信工程环境中认知通信工程的设计、施工、维护和业务规程,这些在通信技术专业实训基地建设中是值得探讨的一个问题。如果沿用通信专业中的电路基础、电子线路、电信网、数字通信原理,以及有线通信或无线通信原理、通信电源、通信工程概预算、综合布线安装工艺等传统的方法实施现代通信技术专业的教学,其方法显然不再适用。因此对这些传统的教学方法和培养思路进行了改革和创新,根据专业特点,在教学内容、教学方法和能力培养等方面,研究并设计了一个符合专业发展需求、企业需求及现代通信发展的全真实验、实训环境,使学生可以方便接受的教学模式,促进专业深层次的发展以及学生能力的提高。     

Estimation of principal points for a multivariate binary distribution using a log-linear model

This article proposes a method for estimating principal points for a multivariate binary distribution, assuming a log-linear model for the distribution. Through numerical simulation studies, the proposed parametric estimation method using a log-linear model is compared with a nonparametric estimation method.     

Extensions of D-optimal minimal designs for symmetric mixture models

The purpose of mixture experiments is to explore the optimum blends of mixture components, which will provide the desirable response characteristics in finished products. D-optimal minimal designs have been considered for a variety of mixture models, including Scheffé's linear, quadratic, and cubic models. Usually, these D-optimal designs are minimally supported since they have just as many design points as the number of parameters. Thus, they lack the degrees of freedom to perform the lack-of-fit (LOF) tests. Also, the majority of the design points in D-optimal minimal designs are on the boundary: vertices, edges, or faces of the design simplex. In this article, extensions of the D-optimal minimal designs are developed for a general mixture model to allow additional interior points in the design space to enable prediction of the entire response surface. Also a new strategy for adding multiple interior points for symmetric mixture models is proposed. We compare the proposed designs with Cornell (1986 Cornell, J.A. (1986). A comparison between two ten-point designs for studying three-component mixture systems. J. Qual. Technol. 18(1):1–15.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) two 10-point designs for the LOF test by simulations.     

我国劳动就业的难点及对策

创造就业机会 ,实现充分就业在任何时期都是重要的宏观经济目标。然而 ,未来 10年我国的就业矛盾仍十分尖锐。本文根据调查资料 ,剖析了我国当前就业问题的表现、影响、形成原因及治理对策。     

古代诗论的现代审美品格

“诗缘情”显示了诗歌生命的内在动因与美的形式特征 ;“境与心”是对诗的审美心理的深层描述 ;“冲淡”体现了古典诗歌重“含蓄”、“自然”的美学方向。这三者一方面总结了诗歌本体的艺术特征 ,另一方面也反映了诗学在禅宗融入之后的突破与进展 ,诗歌艺术开始浸染着诗人的主体人格。