劳动力密集地区非均衡流动——对河南省固始县劳动力流动及县域经济发展的调查

在劳动力密集的河南省,大量输出劳动力可以迅速促进当地经济的发展和人民生活水平的提高,但人们往往忽视从长远看过量输出导致的非均衡流动却可能束缚输出地经济的发展,笔者通过对河南省信阳市固始县为期13天的调研,对这一问题进行了研究。本文描述了劳动力的大量输出对当地经济发展的促进,着重分析了当地劳动力流动的原因,并分析了非均衡流动给当地经济未来发展带来的三个问题。文章将在前半部分从劳动力流动的环境动力和劳动力流动去向的角度,结合劳动力流动的相关理论,对谷围村劳动力流动情况进行分析,并用"吸出模型"解释劳动力非均衡流动带来的问题和产生的原因。文章后半部分从劳动力大量输出对当地县域经济影响的角度分析了在劳动力密集的固始县企业招工难且劳动力成本高于外地的奇怪现象。最后,文章对固始县为实现劳动力均衡流动而采取的措施进行了研究,总结出劳动力过量输出地区的经济发展模式即"固始模式",并对该模式进行了分析。     

On Rates of Convergence for Bayesian Density Estimation

Abstract.  We consider the problem of estimating a compactly supported density taking a Bayesian nonparametric approach. We define a Dirichlet mixture prior that, while selecting piecewise constant densities, has full support on the Hellinger metric space of all commonly dominated probability measures on a known bounded interval. We derive pointwise rates of convergence for the posterior expected density by studying the speed at which the posterior mass accumulates on shrinking Hellinger neighbourhoods of the sampling density. If the data are sampled from a strictly positive, α -Hölderian density, with α  ∈ ( 0,1] , then the optimal convergence rate n^{− α / (2 α +1)} is obtained up to a logarithmic factor. Smoothing histograms by polygons, a continuous piecewise linear estimator is obtained that for twice continuously differentiable, strictly positive densities satisfying boundary conditions attains a rate comparable up to a logarithmic factor to the convergence rate n ^−4/5 for integrated mean squared error of kernel type density estimators.     

On an adaptive version of the Metropolis–Hastings algorithm with independent proposal distribution

In this paper, we present a general formulation of an algorithm, the adaptive independent chain (AIC), that was introduced in a special context in Gåsemyr et al . [ Methodol. Comput. Appl. Probab. 3 (2001)]. The algorithm aims at producing samples from a specific target distribution Π, and is an adaptive, non-Markovian version of the Metropolis–Hastings independent chain. A certain parametric class of possible proposal distributions is fixed, and the parameters of the proposal distribution are updated periodically on the basis of the recent history of the chain, thereby obtaining proposals that get ever closer to Π. We show that under certain conditions, the algorithm produces an exact sample from Π in a finite number of iterations, and hence that it converges to Π. We also present another adaptive algorithm, the componentwise adaptive independent chain (CAIC), which may be an alternative in particular in high dimensions. The CAIC may be regarded as an adaptive approximation to the Gibbs sampler updating parametric approximations to the conditionals of Π.     

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.     

B股与H股及红筹股之间的溢出效应与信息流动

运用向量GARCH-M模型检验了B股与H股及红筹股之间的溢出效应与信息流动.实证结果表明:红筹股对沪深市B股、H股对沪市B股的收益和波动溢出效应均显著存在,而反向的溢出效应均不显著,表明信息是从红筹股向沪深市B股、从H股向沪市B股单向流动的;深市B股与H股之间相互的收益溢出效应均存在,而波动溢出效应均不存在,信息在H股和深市B股之间的流动情况不明显;在信息流动过程中,红筹股始终处于信息领先地位.     

湿蒸汽两相流流量及干度的双参数测量研究

本文采用孔板及均速管组合形式,对汽-水两相流的流量及干度的双参数测量进行了实验研究。实验结果表明,这种测量方法可以满足高干度湿蒸汽测量的要求,具有很好的工业适用性。     

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。     

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。     

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。