Partitioned log-rank tests for the overall homogeneity of hazard rate functions

In survival analysis, it is routine to test equality of two survival curves, which is often conducted by using the log-rank test. Although it is optimal under the proportional hazards assumption, the log-rank test is known to have little power when the survival or hazard functions cross. To test the overall homogeneity of hazard rate functions, we propose a group of partitioned log-rank tests. By partitioning the time axis and taking the supremum of the sum of two partitioned log-rank statistics over different partitioning points, the proposed test gains enormous power for cases with crossing hazards. On the other hand, when the hazards are indeed proportional, our test still maintains high power close to that of the optimal log-rank test. Extensive simulation studies are conducted to compare the proposed test with existing methods, and three real data examples are used to illustrate the commonality of crossing hazards and the advantages of the partitioned log-rank tests.     

我国民法基本制度生态化探究

生态文明时代要求法律制度进行不同程度的生态化.在各种法律制度生态化历程中,民法制度的生态化起着相当重要的作用.民法基本制度的生态化是民法生态化的重要内容,它包括人格权制度的生态化、物权制度的生态化、合同制度的生态化、侵权责任制度的生态化.这其中,环境人格权是人格权制度生态化的主要内容；生态性用益物权是物权制度生态化的重要组成部分；环境物权交易合同是合同制度生态化的主要方面.以损害风险预防、现实损害救济赔偿、恢复责任承担为切入点,采用无过错责任与过错加重责任并用的原则,贯彻环境损害全程监管与责任追究的理念,对环境污染与生态破坏的源头与过程实行全面的控制与追责是侵权责任制度生态化的基本要素.     

长三角创新资源的空间错配与调整政策——基于次级和县级区域的实证研究

依据对长江三角洲次级和县级区域资源配置现状的实证研究发现：一是长江三角洲区域在经历高速重化工业化的同时，开始跨入了内生增长模式的门槛，人力资本的贡献日益显现；二是越来越多的次级区域工业生产能力和技术创新能力正在超越北京、上海以及省会城市，由此国家的科技资源和高等教育资源也应当流向这些区域，使产业、科技、教育资源能够融合在同一个空间，以大大提高整个国家技术创新投入的收益；三是转变经济发展方式和实施创新型国家建设战略的真正落脚点是支持和推动更多的次级和县级区域建立高等教育体系，创造更多的人力资本，开展更多的技术创新活动，使更多的区域采取基于技术进步的增长战略。充足的证据表明，现在到了需要采取一个重视创新资源效率的区域增长战略的时候了。     

小学与经学:段、顾之争与校勘学的取径

段、顾之争的根源是小学与经学之争.段玉裁的研究方法是根基于小学的考据方法,顾千里的研究方法则是具有传统经学特色的方法.段氏关注字句、片段在其他文献中所呈现的不同,然后施展考据功夫以求形成统一的文本;顾氏则更重视对经学家法的遵守,保持在不同家法传承下经文的差异性.从这一点看,顾千里的校勘和解读更符合经学本身的特征.     

Optimal control strategies for dividend payments and capital injections in compound Markov binomial risk model with penalties for deficits

We consider the compound Markov binomial risk model. The company controls the amount of dividends paid to the shareholders as well as the capital injections in order to maximize the cumulative expected discounted dividends minus the discounted capital injections and the discounted penalties for deficits prior to ruin. We show that the optimal value function is the unique solution of an HJB equation, and the optimal control strategy is a two-barriers strategy given the current state of the Markov chain. We obtain some properties of the optimal strategy and the optimal condition for ruining the company. We offer a high-efficiency algorithm for obtaining the optimal strategy and the optimal value function. In addition, we also discuss the optimal control problem under a restriction of bounded dividend rates. Numerical results are provided to illustrate the algorithm and the impact of the penalties.     

Assessing Participation and Effectiveness of the Peer-Led Approach in Youth Sexual Health Education: Systematic Review and Meta-Analysis in More Developed Countries

Sexual health education for young people is crucial not only for development of norms but also for protection against vulnerabilities during this stage in life. Although several systematic reviews have examined the effectiveness of peer-led sex education, none have focused on the extent of peer participation. The purpose of this review was to evaluate peer-led sexual health education interventions in more developed countries (MDCs). Electronic and manual searches across five social science, education, and medical databases were conducted. Fifteen articles were selected in total. Most (10 of 15) studies gave low or no responsibility to peers. The majority of articles found improvements in sexual health knowledge (13 of 14) and attitudes (11 of 15) at postintervention stages. Two studies showed improved self-efficacy, and three showed behavioral changes. A preliminary synthesis of effectiveness and level of participation was done. Meta-analysis revealed a large effect on knowledge change (Hedges’ g = 0.84, 95% confidence interval [CI]: 0.43 to 1.25) and a medium effect on attitude change (Hedges’ g = 0.49, 95% CI: 0.19 to 0.80). Peer-led interventions could be a powerful tool. This review shows that this approach is effective in changing knowledge and attitudes but not behaviors. Further research and action are needed to understand optimal implementation.     

Bayesian adaptive dose‐escalation designs for simultaneously estimating the optimal and maximum safe dose based on safety and efficacy

The main purpose of dose‐escalation trials is to identify the dose(s) that is/are safe and efficacious for further investigations in later studies. In this paper, we introduce dose‐escalation designs that incorporate both the dose‐limiting events and dose‐limiting toxicities (DLTs) and indicative responses of efficacy into the procedure. A flexible nonparametric model is used for modelling the continuous efficacy responses while a logistic model is used for the binary DLTs. Escalation decisions are based on the combination of the probabilities of DLTs and expected efficacy through a gain function. On the basis of this setup, we then introduce 2 types of Bayesian adaptive dose‐escalation strategies. The first type of procedures, called “single objective,” aims to identify and recommend a single dose, either the maximum tolerated dose, the highest dose that is considered as safe, or the optimal dose, a safe dose that gives optimum benefit risk. The second type, called “dual objective,” aims to jointly estimate both the maximum tolerated dose and the optimal dose accurately. The recommended doses obtained under these dose‐escalation procedures provide information about the safety and efficacy profile of the novel drug to facilitate later studies. We evaluate different strategies via simulations based on an example constructed from a real trial on patients with type 2 diabetes, and the use of stopping rules is assessed. We find that the nonparametric model estimates the efficacy responses well for different underlying true shapes. The dual‐objective designs give better results in terms of identifying the 2 real target doses compared to the single‐objective designs.     

Least squares estimation of varying‐coefficient hazard regression with application to breast cancer dose‐intensity data

To enhance modeling flexibility, the authors propose a nonparametric hazard regression model, for which the ordinary and weighted least squares estimation and inference procedures are studied. The proposed model does not assume any parametric specifications on the covariate effects, which is suitable for exploring the nonlinear interactions between covariates, time and some exposure variable. The authors propose the local ordinary and weighted least squares estimators for the varying‐coefficient functions and establish the corresponding asymptotic normality properties. Simulation studies are conducted to empirically examine the finite‐sample performance of the new methods, and a real data example from a recent breast cancer study is used as an illustration. The Canadian Journal of Statistics 37: 659–674; 2009 © 2009 Statistical Society of Canada     

西北贫困民族聚居区学校体育特征研究

在层层比较中作者们认为西北贫困民族聚居区学校体育具有总体比较落后、地域特征明显;观念比较陈旧、经费严重不足;民族特色突出、发展潜力较大;少数民族青少年为主体,多数以一课两操为支撑四个方面的基本特征。