A Stochastic Model for Assessing Chlamydia trachomatis Transmission Risk Using Longitudinal Observational Data

Bacterium Chlamydia trachomatis causes genital chlamydia infection. Yet little is known about the transmission efficiency of this organism. Ethical constraint against exposing healthy subjects to infected partners precludes the possibility of quantifying transmission risk through controlled experiments. This research proposes an alternative strategy that relies on observational data. Specifically, we present a stochastic model that treats longitudinally observed infection states in a group of young women as a Markov process. The proposed model explicitly accommodates the parameters of C. trachomatis transmission, including per-encounter sexually transmitted infection (STI) acquisition risks, with and without condom protection, and the probability of antibiotic treatment failure. The male-to-female transmission probability of C. trachomatis is then estimated by combining the per-encounter disease acquisition risk and the organism's prevalence in the male partner population. The proposed model is fitted in a Bayesian computational framework.     

电子商务产业链拓展机制研究——以杭州1为例

根据国家“十二五”流通业规划的初步构想，电子商务的市场容量将从2010年的4．5万亿元增加到12万亿元以上，并将成为扩消费的重要渠道。“十二五”期间，必将是电子商务产业链整合优化的关键时期。本文以“中国电子商务之都”杭州为样本，通过实地调研数十家电子商务相关企业及行业协会，跟踪了解电子商务发展趋势，对电子商务产业链拓展问题进行了系统研究。     

试论南宋名宦汪纲对绍兴城市建设的贡献

南宋名宦汪纲在两任绍兴知府期间,从绍兴城市发展的长远考虑,进行了一次有规划、有组织的大规模城市建设.由此完善了绍兴城市的厢坊建置、街衢布局与河道分布,为绍兴城市的可持续发展起到了奠基和推进作用.     

关于“用高锰酸钾溶液氧化乙烯和乙炔”的实验的几点看法

本文研究了用不同浓度、不同用量的高锰酸钾溶液在不同条件下氧化乙烯和乙炔，并得到不同的产物的实验，从而在理论上加以论述，并对大专院校不同实验书中有关此实验提出一些不同看法。     

浅议地方可持续发展问题的对策——兼论地方环境立法

在可持续发展理论的基础上,地方可持续发展问题应运而生.在地方可持续发展建设上,必须政策、法律多种措施并举,加强决策能力,建立投入机制,根本改变经济发展模式,进行宣传教育和人才培养.同时,加强地方环境立法.     

世界欠发达国家区域经济合作的发展与中国的实践

建立区域经济合作组织已经成为世界欠发达国家和地区参与经济一体化的重要选择.南美洲、非洲、亚洲的欠发达国家的区域经济合作的实践昭示了南南合作的新趋势.本文从南美共同体的成立与发展、非洲联盟的发展现状与展望、中国参与欠发达地区区域经济合作的实践三方面分析了区域经济集团间的合作及超越地缘界限的区域合作.     

在不同文明撞击中发展的蒙古文学

在不同文明撞击下发展起来的蒙古文学，具有四个显著特征：其一，文化上的兼容性和自立性，导致了蒙古文学的繁荣发展和稳定生存。其二，民族历史的艰难历程和经济发展的淤滞延缓，决定了文学内容的相对集中和文体表述的趋于定型。其三，诗性的语言和直观的思维，确立了韵文作品的主导地位和创作模式的固定倾向。其四，深厚的民间文学传统，导致了口头文学与书面文学的相互交融。     

Using generalized doubly robust estimator to estimate average treatment effects of multiple treatments in observational studies

The generalized doubly robust estimator is proposed for estimating the average treatment effect (ATE) of multiple treatments based on the generalized propensity score (GPS). In medical researches where observational studies are conducted, estimations of ATEs are usually biased since the covariate distributions could be unbalanced among treatments. To overcome this problem, Imbens [The role of the propensity score in estimating dose-response functions, Biometrika 87 (2000), pp. 706–710] and Feng et al. [Generalized propensity score for estimating the average treatment effect of multiple treatments, Stat. Med. (2011), in press. Available at: http://onlinelibrary.wiley.com/doi/10.1002/sim.4168/abstract] proposed weighted estimators that are extensions of a ratio estimator based on GPS to estimate ATEs with multiple treatments. However, the ratio estimator always produces a larger empirical sample variance than the doubly robust estimator, which estimates an ATE between two treatments based on the estimated propensity score (PS). We conduct a simulation study to compare the performance of our proposed estimator with Imbens’ and Feng et al.’s estimators, and simulation results show that our proposed estimator outperforms their estimators in terms of bias, empirical sample variance and mean-squared error of the estimated ATEs.     

Comparison of clustering algorithms on generalized propensity score in observational studies: a simulation study

In observational studies, unbalanced observed covariates between treatment groups often cause biased inferences on the estimation of treatment effects. Recently, generalized propensity score (GPS) has been proposed to overcome this problem; however, a practical technique to apply the GPS is lacking. This study demonstrates how clustering algorithms can be used to group similar subjects based on transformed GPS. We compare four popular clustering algorithms: k-means clustering (KMC), model-based clustering, fuzzy c-means clustering and partitioning around medoids based on the following three criteria: average dissimilarity between subjects within clusters, average Dunn index and average silhouette width under four various covariate scenarios. Simulation studies show that the KMC algorithm has overall better performance compared with the other three clustering algorithms. Therefore, we recommend using the KMC algorithm to group similar subjects based on the transformed GPS.     

关于高校举办多媒体教学比赛的探讨

本文分析了高校举办多媒体教学比赛的可行性和必要性 ,并结合本校开展多媒体教学比赛的具体情况与效果 ,探讨了高校多媒体教学比赛的举办方式、组织与实施细节、评估指标体系等 ,并提出了独到的见解