Optimal scaling of Metropolis algorithms: Heading toward general target distributions

The authors provide an overview of optimal scaling results for the Metropolis algorithm with Gaussian proposal distribution. They address in more depth the case of high‐dimensional target distributions formed of independent, but not identically distributed components. They attempt to give an intuitive explanation as to why the well‐known optimal acceptance rate of 0.234 is not always suitable. They show how to find the asymptotically optimal acceptance rate when needed, and they explain why it is sometimes necessary to turn to inhomogeneous proposal distributions. Their results are illustrated with a simple example.     

A modified false discovery rate multiple-comparisons procedure for discrete data, applied to human immunodeficiency virus genetics

Summary.  To help to design vaccines for acquired immune deficiency syndrome that protect broadly against many genetic variants of the human immunodeficiency virus, the mutation rates at 118 positions in HIV amino-acid sequences of subtype C versus those of subtype B were compared. The false discovery rate (FDR) multiple-comparisons procedure can be used to determine statistical significance. When the test statistics have discrete distributions, the FDR procedure can be made more powerful by a simple modification. The paper develops a modified FDR procedure for discrete data and applies it to the human immunodeficiency virus data. The new procedure detects 15 positions with significantly different mutation rates compared with 11 that are detected by the original FDR method. Simulations delineate conditions under which the modified FDR procedure confers large gains in power over the original technique. In general FDR adjustment methods can be improved for discrete data by incorporating the modification proposed.     

台湾的金融改革及其启示

要本文在分析台湾实行金融改革动因的基础上，概述了台湾金融改革的内容，评述了台湾实行金融自由化的目的－建立区域金融中心的构想，并就这一改革给大陆带来的启示作出了思考。     

不同添加剂预混料对哺乳仔猪生产性能的影响

以窝为单位将 70窝哺乳仔猪随机分为 7组 ,设 1个对照组 (试验I组 ) ,6个试验组。试验组分别添加 2 0 0mg/kg派富 (含芽胞杆菌等复合微生态制剂 ) (Ⅱ )、1%的甲酸吡啶铬 2 0 0mg/kg(Ⅲ )、2 0mg/kg泰乐菌素 (Ⅳ )、1%中药免疫增强剂 (黄芪、远智等复合中草药 ) (Ⅴ )、1%的益康XP(酵母培养物 ) (Ⅵ )以及 2 0mg/kg的硝呋烯宗 (Ⅶ )。经过 15d的试验 ,其结果表明 :试验组较对照组提高日增重 11.37% - 34.12 % ,其中Ⅴ、Ⅵ组达到显著水平 (p <0 .0 5 ) ;提高采食量 1.5 9% - 12 .30 % ;降低饲料增重比 8.4 % - 2 0 .2 0 % ;降低仔猪腹泻频次 10 .34- 31.0 3%。经无菌粪样检验 ,试验各组大肠杆菌、沙门氏菌、葡萄球菌数均低于对照组 ,差异不显著 (p >0 .0 5 ) ;而乳酸杆菌、双岐杆菌均高于对照组 ,差异不显著 (p >0 .0 5 )。经部分血液指标分析 ,试验各组的血液各项理化指标均在正常范围内 ,且各组间差异不显著 (p >0 .0 5 )。     

引导与干预:不同汇率制度中的央行行为分析

广义汇率目标区制包括介于浮动汇率制与固定汇率制之间的所有的汇率安排,中央银行外汇市场干预的不同,决定了汇率目标区制中类型的不同。在中央银行强有力的干预下,中心汇率和目标区公开是最具吸引力的一种目标区制,其根本特性就在于其汇率形成机制的内在稳定性,从而也是构建未来人民币汇率目标区制的较好选择。     

信息不对称与人的经济行为

信息不对称及其经济效应是信息经济学研究的中心问题,本文依据信息经济学和行为科学理论,从现实经济生活出发,系统地阐述了信息不对称的内涵,论证了信息不对称的必然性,探讨了信息不对称条件下交易双方的经济行为,提出了信息不对称条件下卖方(或代理方)违规败德行为的函数式,最后讨论了信息不对称造成的经济后果,提出了解决这一问题的思路。     

改进的OBS长度自适应门限组装算法

现有OBS长度自适应组装算法的突发数据长度门限的选择虽然随着业务流的变化而变化,克服了固定长度门限算法输出的突发数据的突发性,但仍然没有考虑业务流的自相似特性,因此不能有效降低输出突发数据的自相似程度和分组阻塞率。针对这一问题,该文提出了一种改进的OBS长度自适应门限组装算法,能根据到达的网络业务流的自相似特性自适应地调整长度门限值。仿真结果表明:在相同的调度算法下,更能降低业务流的自相似性,分组阻塞率降低一个数量级。     

四川省高等教育与区域经济发展关系研究

在对四川省经济发展和高等教育发展现状进行考查的基础上,从理论层次上论述二者发生关系的可能性,运用模糊统计方法得出四川省高等教育发展与经济发展呈强相关关系,并通过对四川省经济发展特点和劳动力人才市场供求状况的分析,指出四川省高等教育在适应经济发展过程中所存在的问题,进而提出针对性的发展对策,供四川省高等教育改革与发展决策参考。     

房价上涨对我国人口出生率的影响——基于省级面板数据的实证分析

人口数量和结构是影响我国可持续发展的关键因素,住房是人民群众安居乐业的刚需。近年来,我国人口出生率持续下降。为了实现经济高质量发展,缓解人口危机是当前亟待解决的重要问题。为了探究房价上涨对于我国人口出生率的影响,利用31个省级行政区2010—2019年的面板数据和加权最小二乘法进行实证分析,结果表明：房价上涨对人口出生率产生显著的负向影响,住房价格平均上涨1%将导致人口出生率下降0.13%~0.22%;房价上涨对人口出生率的影响在东部省份以挤出效应为主、在中西部省份是以财富效应为主。当前,通过遏制住房投资投机性需求、给予“刚需”人群购房贷款优惠、适量增加东部省份土地供给等手段,可以助力解决我国当前的人口问题。     

Dynamic reliability models with conditional proportional hazards

A dynamic approach to the stochastic modelling of reliability systems is further explored. This modelling approach is particularly appropriate for load-sharing, software reliability, and multivariate failure-time models, where component failure characteristics are affected by their degree of use, amount of load, or extent of stresses experienced. This approach incorporates the intuitive notion that when a set of components in a coherent system fail at a certain time, there is a jump from one structure function to another which governs the residual lifetimes of the remaining functioning components, and since the component lifetimes are intrinsically affected by the structure function which they constitute, then at such a failure time there should also be a jump in the stochastic structure of the lifetimes of the remaining components. For such dynamically-modelled systems, the stochastic characteristics of their jump times are studied. These properties of the jump times allow us to obtain the properties of the lifetime of the system. In particular, for a Markov dynamic model, specific expressions for the exact distribution functions of the jump times are obtained for a general coherent system, a parallel system, and a series-parallel system. We derive a new family of distribution functions which describes the distributions of the jump times for a dynamically-modelled system.