Sample size determination for testing equality in frequency data under an incomplete block crossover design

When there are more than two treatments under comparison, we may consider the use of the incomplete block crossover design (IBCD) to save the number of patients needed for a parallel groups design and reduce the duration of a crossover trial. We develop an asymptotic procedure for simultaneously testing equality of two treatments versus a control treatment (or placebo) in frequency data under the IBCD with two periods. We derive a sample size calculation procedure for the desired power of detecting the given treatment effects at a nominal-level and suggest a simple ad hoc adjustment procedure to improve the accuracy of the sample size determination when the resulting minimum required number of patients is not large. We employ Monte Carlo simulation to evaluate the finite-sample performance of the proposed test, the accuracy of the sample size calculation procedure, and that with the simple ad hoc adjustment suggested here. We use the data taken as a part of a crossover trial comparing the number of exacerbations between using salbutamol or salmeterol and a placebo in asthma patients to illustrate the sample size calculation procedure.     

Parametric Inference in Stationary Time Series Models with Dependent Errors

This article is concerned with inference for the parameter vector in stationary time series models based on the frequency domain maximum likelihood estimator. The traditional method consistently estimates the asymptotic covariance matrix of the parameter estimator and usually assumes the independence of the innovation process. For dependent innovations, the asymptotic covariance matrix of the estimator depends on the fourth‐order cumulants of the unobserved innovation process, a consistent estimation of which is a difficult task. In this article, we propose a novel self‐normalization‐based approach to constructing a confidence region for the parameter vector in such models. The proposed procedure involves no smoothing parameter, and is widely applicable to a large class of long/short memory time series models with weakly dependent innovations. In simulation studies, we demonstrate favourable finite sample performance of our method in comparison with the traditional method and a residual block bootstrap approach.     

Community Based Rural Health Care in India

SUMMARY

India is a large country, geographically as well as popula-tionwise. The majority of its population lives in rural areas, i.e., villages. Again, most of the villages are in remote areas. The State has been making sincere efforts to make the basic social services accessible to all in the rural area. Health being one of the vital services, it has been a challenging task before the State to extend it to the remote rural areas, many of which are not yet connected by motorable roads. As a result of various experiments carried out over the last five decades, the State has developed a fairly well-designed primary health care service, and it is in operation in rural areas. However, there appears to be a striking gap between the delivery of health services in rural areas and utilization of the services by the people. Attempts have been made in this article to apprise the readers of the health service system in India, and it discusses the issue of health service delivery at the village level. The discussion is based on a small study carried out in a rural area in the State of West Bengal (India) where students of social work of the University to which the author belongs are placed for field work. Following the inputs received through supervision of the students' work, the study was initiated and conducted.

This article based on the study seeks to focus on peoples' perception of the health services as provided by the State in rural areas, which in turn gets reflected in the extent to which they utilize the services. Social workers being an integral part of the health set up, their role bears special significance. Discussion, therefore, centres on scope for social work intervention at the community level as well as in institutional level of the health service delivery system to make the services meaningful and effective in rural areas. In fact, it has to take the leadership role in reforming the service delivery system when required.     

印尼J区块层序地层与沉积相特征研究

利用层序地层学理论,对印尼J区块古近系—新近系的层序地层和沉积相特征进行了研究。古近系—新近系可以分为7个中期基准面旋回（SQ1SQ7）和17个短期基准面旋回。SQ1SQ7沉积时期,沉积环境从陆相河流环境逐渐过渡到三角洲环境和浅海环境,再到河流环境,为一完整的水进-水退旋回。中下部层序上升旋回占主体,属海进式沉积组合序列;上部层序下降旋回占主体,多为海退式沉积组合序列。结合层序特征,指出区块西部凸起带SQ5旋回的浊积砂体、基底风化壳、碳酸盐岩台地和东部斜坡带的下切谷为区块的有利勘探区带。研究结果对该盆地的石油勘探具有指导意义。     

价格传导问题综述及量化分析

本文通过对国际市场价格变动向我国市场价格传导②、我国上游产品价格变动向下游产品价格传导的定量与定性分析,描述了国际市场价格向我国市场价格传导,以及我国上游行业价格向下游行业价格传导的规律,并据此对“上下游产品价格传导阻滞”问题进行了解释③。通过分析,得出初步结论：当前我国上游产品价格上涨向下游产品价格的传导已充分显现,并不存在阻滞问题,上下游产品市场竞争格局不同是导致其价格传导变动幅度不一致的主要原因。     

相位旋转的速率为2的空时分组码

速率为2的空时分组码(R2-STBC)能达到全速率全分集,然而其译码复杂度与调制阶数的平方成正比。为了降低译码复杂度,提出了一种基于相位旋转的、速率为2的空时分组码(PR-R2-STBC),发送端根据反馈信息将部分发送信号旋转一定的角度,实现了信号在传输过程中两两正交,从而使得其译码复杂度与调制阶数成正比。仿真结果显示,与R2-STBC相比,该编码仅需反馈7 bit就极大地降低了译码复杂度。     

Joint modified block replacement and production/inventory control policy for a failure-prone manufacturing cell

This paper considers a joint preventive maintenance (PM) and production/inventory control policy of an unreliable single machine, mono-product manufacturing cell with stochastic non-negligible corrective and preventive delays. The production/inventory control policy, which is based on the hedging point policy (HPP), consists in building and maintaining a safety stock of finished products in order to respond to demand and to avoid shortages during maintenance actions. Without considering the impact of preventive and corrective actions on the overall performance of the production system, most authors working in the reliability and maintainability domains confirm that the age-based preventive maintenance policy (ARP) outperforms the classical block-replacement policy (BRP). In order to reduce wastage incurred by the classical BRP, we consider a modified block replacement policy (MBRP), which consists in canceling a preventive maintenance action if the time elapsed since the last maintenance action exceeds a specified time threshold. The main objective of this paper is to determine the joint optimal policy that minimizes the overall cost, which is composed of corrective and preventive maintenance costs as well as inventory holding and backlog costs. A simulation model mimicking the dynamic and stochastic behavior of the manufacturing cell, based on more realistic considerations of the real behavior of industrial manufacturing cells, is proposed. Based on simulation results, the joint optimal MBRP/HPP parameters are obtained through a numerical approach that combines design of experiment, analysis of variance and response surface methodologies. The joint optimal MBRP/HPP policy is compared to classical joint ARP/HPP and BRP/HPP optimal policies, and the results show that the proposed MBRP/HPP outperforms the latter. Sensitivity analyses are also carried out in order to confirm the superiority of the proposed MBRP/HPP, and it is observed that for practitioners, the proposed joint MBRP/HPP offers not only cost savings, but is also easy to manage, as compared to the ARP/HPP policy.     

参数可变的多混沌映射加密系统

利用混沌映射具有对初值和系统参数的敏感性以及轨道的不确定性,提出一种基于多个一维混沌映射的加密算法。该加密算法使用线性同余随机数发生器产生混沌映射的系统参数和3个一维混沌映射的使用顺序,同时通过输出反馈方式动态改变混沌映射初值、迭代次数以及线性同余随机数发生器参数。实验结果和安全性分析表明,该算法密钥空间大,具有对明文和密钥的敏感性,能有效抵抗选择明文等穷举攻击和统计分析攻击。     

我国公共政策执行阻滞的文化因素分析及对策

公共政策执行在整个政策系统中具有至关重要的地位和作用。由于我国文化因素的影响,公共政策在执行过程中往往容易出现阻滞现象,严重影响政策目标的有效实现。基于文化视角,通过对我国公共政策执行阻滞的文化因素分析,提出摒弃传统落后观念,强化政治社会化,完善公共政策的对策。     

Chain graph models: topological sorting of meta-arrows and efficient construction of $${\mathcal{B}}$$ -essential graphs

Essential graphs and largest chain graphs are well-established graphical representations of equivalence classes of directed acyclic graphs and chain graphs respectively, especially useful in the context of model selection. Recently, the notion of a labelled block ordering of vertices was introduced as a flexible tool for specifying subfamilies of chain graphs. In particular, both the family of directed acyclic graphs and the family of “unconstrained” chain graphs can be specified in this way, for the appropriate choice of . The family of chain graphs identified by a labelled block ordering of vertices is partitioned into equivalence classes each represented by means of a -essential graph. In this paper, we introduce a topological ordering of meta-arrows and use this concept to devise an efficient procedure for the construction of -essential graphs. In this way we also provide an efficient procedure for the construction of both largest chain graphs and essential graphs. The key feature of the proposed procedure is that every meta-arrow needs to be processed only once.