Properties of the weighted log‐rank test in the design of confirmatory studies with delayed effects

Proportional hazards are a common assumption when designing confirmatory clinical trials in oncology. This assumption not only affects the analysis part but also the sample size calculation. The presence of delayed effects causes a change in the hazard ratio while the trial is ongoing since at the beginning we do not observe any difference between treatment arms, and after some unknown time point, the differences between treatment arms will start to appear. Hence, the proportional hazards assumption no longer holds, and both sample size calculation and analysis methods to be used should be reconsidered. The weighted log‐rank test allows a weighting for early, middle, and late differences through the Fleming and Harrington class of weights and is proven to be more efficient when the proportional hazards assumption does not hold. The Fleming and Harrington class of weights, along with the estimated delay, can be incorporated into the sample size calculation in order to maintain the desired power once the treatment arm differences start to appear. In this article, we explore the impact of delayed effects in group sequential and adaptive group sequential designs and make an empirical evaluation in terms of power and type‐I error rate of the of the weighted log‐rank test in a simulated scenario with fixed values of the Fleming and Harrington class of weights. We also give some practical recommendations regarding which methodology should be used in the presence of delayed effects depending on certain characteristics of the trial.     

氨基吡啶树脂的应用研究进展

对氨基吡啶树脂作为螯合树脂和超亲核催化剂的应用研究进行了综合评述,并展望了今后的研究方向.     

内部审计在公司治理中的作用

公司治理是伴随着现代企业而产生发展的,它通过一套制度的安排对企业的权、责、利进行约束。而内部审计正是对这套制度的再监督。本文从公司治理的角度,根据内部审计的涵义和职能,在分析内部审计与公司治理联系的基础上,论述内部审计在公司治理中的作用。同时,结合我国公司治理的现状,揭示内部审计工作存在的问题和相应的解决措施。     

浅谈中外合作办学学校需妥善处理的三方面关系

中外合作办学是中国教育国际化战略的重大探索,也是一项教育系统工程。中外合作办学学校作为教育实施的主体,妥善处理与政府教育主管部门、学生及其家长、行业中介组织的关系,是学校健康和谐发展的关键。学校要在政府的宏观调控下承担教育主体的责任;维护受教育者权益,创建学校的教育品牌;并注意适当发挥行业中介的作用。     

改性脲醛树酯粘合剂的研制

本文介绍了三聚氰胺改性脲醛树酯粘合剂的配方、操作工艺及产品性能。     

On the effectiveness of cognitive feedback from an interface agent

The objective of this study was to determine the impact of task information (TI) provided by an interface agent during the idea evaluation and integration step of the problem formulation stage of the problem solving process. The effectiveness assessment was based on solving diagnostic decision problems in the domain of complex industrial machinery. Ten domain experts participated in this study. Decision support was provided by a case-based reasoning system. Findings suggest that TI provided by the interface agent had no effect on the decision maker's performance, nor on the associated cognitive effort. However, a verbal protocol analysis revealed that the ten subjects used the interface agent to verify their decision processes. The results and their implications are discussed with respect to current findings in the area of decision support systems.     

基于需要层次理论的保险代理人分类激励机制指标体系设计

针对保险代理人的具体情况和实际需求，将马斯洛的需要层次理论灵活地应用到实际当中，设计出一系列量化分类指标，运用数理统计方法，进行加权汇总后得出几个总值，对这几个总值的大小进行排序，根据排序的结果科学理性地将保险代理人分成若干类别，在对保险代理人管理过程中可以针对不同类别的代理人采取不同激励措施，进而有效而又低成本地解决保险业对代理人激励不力的问题。     

本科院校课程建设评价指标体系研究

课程建设水平的高低直接影响着高校教学质量的高低和所培养人才的情况.而课程建设评价指标设立的正确与否,则成为正确评价课程建设水平的     

Training needs of extension agents’ regarding organic agriculture in Saudi Arabia

The purpose of this study was to investigate the needs of extension agents for training on organic agriculture (OA) in the Riyadh Region. Fifty-five percent (n = 69) of extension agents were selected to collect data through an electronic survey. Results indicated that extension agents in the Riyadh Region cited on job training as a main source for acquiring knowledge in OA. Agents expressed interest in receiving training in OA in general, OA marketing, and transitioning to OA. The most useful resources were field days at organic farms, OA training sessions at colleges, and attending OA trial plots. There were no differences in the level of interest in training; however, there were significant differences between individuals in terms of their experience in OA, job responsibility for providing information related to OA, and area of specialization in their job. This study recommends developing professional training programs based on the current knowledge of extension agents.     

聚乙二醇-硫酸铵双水相体系萃取分离食用色素的研究

研究了硫酸铵-聚乙二醇（PEG）双水相体系中,PEG浓度、（NH4）2SO4用量、Trition X-100用量、溶液酸度等因素对常见食用色素叶绿素铜钠盐（SCC）萃取率的影响。研究表明,在50mL的总体积中,聚乙二醇的浓度为30％,10％的SCC溶液的体积为1mL,（NH4）2SO4用量为10．0g,表面活性剂Trition X-100的用量为1．0mL,在中性或微碱性条件下,叶绿素铜钠盐的萃取率达97．98％。叶绿素铜钠盐最大吸收峰位于632nm,实验测定其溶液体积在0—1．2mL范围内符合比耳定律,标准工作曲线为Y=1．0117x＋0．0055,R=0．9999。在实验条件下,金属离子Zn^2＋、Mn^2＋、Mg^2＋、Fe^2＋、Ni^2＋、Cu^2＋对SCC的萃取均不干扰。