Adherence to three different strategies to prevent early onset GBS infection in newborns

ProblemDespite the introduction of preventive guidelines, no decrease in the incidence of early onset infection was observed.BackgroundEarly onset group B streptococcal (EOGBS) infection is an important cause of neonatal morbidity and mortality.AimOur study was conducted to determine adherence to three guideline-based group B streptococcus (GBS) preventive strategies.MethodsA prospective experimental study clustered by obstetric collaboration region was performed between March 2013 and August 2014 among midwives, obstetricians and paediatricians in the Netherlands. At baseline, the three regions operated according to the Dutch preventive strategy (founded on the risk-based strategy) in order to prevent EOGBS infection, whereas in the study period they followed either the risk-based, the combination or the Dutch strategy. Adherence was measured prospectively per pregnant woman, using predefined core elements of each preventive strategy: identification of risk factors, maternal GBS screening, application of intrapartum antibiotic prophylaxis and observation of the child. Data about adherence to the core elements were collected from medical records, maternal questionnaires and laboratory test results.FindingsIn the three regions, a total of 121 care providers and 1562 women participated.We found an overall adherence of 90% to the risk-based strategy, 57% to the combination strategy and 89% to the Dutch strategy. Adherence to a strategy in case women had EOGBS risk factors was below 20% in all strategies.DiscussionThe majority of women with EOGBS risk factors did not receive the care prescribed by any of three preventive strategies and were not treated optimally.ConclusionThe risk-based and the Dutch strategy are the recommended strategies for implementation.     

B2C电子商务败因:创新范式研究

B2C电子商务的发展经历了泡沫-失败-复苏的周期,深刻分析其失败的原因,对于今后B2C的发展是有指导意义的。B2C商务模式是一种创新行为,B2C的失败是一种创新行为的失败。本文采用创新理论框架对其失败的原因进行分析。     

LOG-PERIODOGRAM ESTIMATION OF LONG MEMORY VOLATILITY DEPENDENCIES WITH CONDITIONALLY HEAVY TAILED RETURNS

Many recent papers have used semiparametric methods, especially the log-periodogram regression, to detect and estimate long memory in the volatility of asset returns. In these papers, the volatility is proxied by measures such as squared, log-squared, and absolute returns. While the evidence for the existence of long memory is strong using any of these measures, the actual long memory parameter estimates can be sensitive to which measure is used. In Monte-Carlo simulations, I find that if the data is conditionally leptokurtic, the log-periodogram regression estimator using squared returns has a large downward bias, which is avoided by using other volatility measures. In United States stock return data, I find that squared returns give much lower estimates of the long memory parameter than the alternative volatility measures, which is consistent with the simulation results. I conclude that researchers should avoid using the squared returns in the semiparametric estimation of long memory volatility dependencies.     

实用电源变压器检测台

该电路设计简单、构思新颖 ,适合小批量测试小型电源变压器的空载电流、额定电流及次级空载电压、满载电压、负载电流等参数     

试析国债二级市场的流动性建设问题

国债流通市场 ,又称二级市场 ,与国债一级市场互为依存。二级市场的流动性强弱在一定程度上制约着国债一级市场的增发空间。长期以来 ,我国国债二级市场的发展滞后于一级市场 ,市场分割的存在致使二级市场表现为流动性不足。本文对此问题进行了考察 ,并提出了相应的对策。     

A class of count models and a new consistent test for the Poisson distribution

We define a class of count distributions which includes the Poisson as well as many alternative count models. Then the empirical probability generating function is utilized to construct a test for the Poisson distribution, which is consistent against this class of alternatives. The limit distribution of the test statistic is derived in case of a general underlying distribution, and efficiency considerations are addressed. A simulation study indicates that the new test is comparable in performance to more complicated omnibus tests.     

Lower bounds on expectations of positive L-statistics from without-replacement models

We consider samples drawn without replacement from finite populations. We establish optimal lower non-negative and upper non-positive bounds on the expectations of linear combinations of order statistics centered about the population mean in units generated by the population central absolute moments of various orders. We also specify the general results for important examples of sample extremes, Gini mean differences and sample range. The paper completes the results of Papadatos and Rychlik [2004. Bounds on expectations of L-statistics from without replacement samples. J. Statist. Plann. Inference 124, 317–336], where sharp negative lower and positive upper bounds on the expectations of the combinations were presented for the without-replacement samples.     

Wilcoxon–Mann–Whitney test for stratified samples and Efron's paradox dice

Two-treatment multi-center clinical trials are the most common type of clinical trials in practice. The aim of this paper is to discuss a curious property of certain standard nonparametric procedures used in the analysis of such clinical trials. Different analyses of a simulated data example are presented, which lead to contrasting and surprising results. The source of the potentially misleading outcome is then explored while relating the simulated data with the concept of Efron's paradox dice and the notion of nontransitivity. With the root of the problem established, an alternate nonparametric method from the literature is shown to address the problem. Finally, pointing out an interpretational concern of using the alternate procedure, a modification to this procedure is also suggested and corresponding theoretical results are presented.     

Two-stage Huber estimation

In this paper we propose a new robust estimator in the context of two-stage estimation methods directed towards the correction of endogeneity problems in linear models. Our estimator is a combination of Huber estimators for each of the two stages, with scale corrections implemented using preliminary median absolute deviation estimators. In this way we obtain a two-stage estimation procedure that is an interesting compromise between concerns of simplicity of calculation, robustness and efficiency. This method compares well with other possible estimators such as two-stage least-squares (2SLS) and two-stage least-absolute-deviations (2SLAD), asymptotically and in finite samples. It is notably interesting to deal with contamination affecting more heavily the distribution tails than a few outliers and not losing as much efficiency as other popular estimators in that case, e.g. under normality. An additional originality resides in the fact that we deal with random regressors and asymmetric errors, which is not often the case in the literature on robust estimators.     

用于1553总线控制器的存储管理单元设计

从消息队列的数据存储结构定义、存储空间规划和控制过程设计三方面讨论了MIL-STD-1553/1773总线控制器的设计实现。在总线控制器的模块化设计方案中,这三个方面构成了总线控制器的核心模块棗存储管理单元,应用该方案可实现具有多消息自动处理功能的总线控制器。