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.     

论税收筹划与税收优惠政策目标实现的关系

税收优惠政策是我国目前广泛应用的重要财政工具之一,影响政府税收优惠政策目标能否有效实现的因素很多,其中纳税人的税收优惠政策筹划活动是一个重要影响因素,通过对两者及其关系的研究,对政府税收优惠政策目标的确定及如何更好地利用纳税人的税收优惠政策筹划确保预期目标的实现,具有重要意义。     

有机构成调整下劳动就业问题的思考

资本有机构成理论是马克思分析资本积累三大历史趋势的首要内容,深刻认识资本有机构成的内涵,特别是深刻认识有机构成发展趋势的内涵,对于调整社会产业结构、经济结构以及就业结构;对于充分认识经济形势变化形成劳动就业给社会带来的压力,进行事前引导和调整;在理论和实践上都将有着重大影响和深刻的指导意义。     

试论我国金融结构变化及其对货币政策的影响

随着我国市场化进程的不断发展,我国金融结构发生了明显的变化。以这些变化的影响为背景,对我国金融结构的变化特征进行分析和揭示,并阐释了引发这些变化的原因以及它对国家货币政策所产生的作用,在此基础上,进一步提出了完善我国金融结构和提高我国货币政策效果的相关政策建议。     

企业资本结构与产品市场战略

直到20世纪80年代,企业资本结构对产品市场竞争的影响才引起经济学家的广泛关注.对于这一问题的研究,存在着两种截然不同的理论结论:一种观点认为企业债务水平的提高会使其在产品市场竞争中更为强硬,增强其竞争力;另一种观点则恰好相反.事实上,企业的融资决策具有两种不同的间接效应:代理效应和策略效应.企业的融资决策在其代理效应和策略效应的平衡点达到最优.企业的融资决策与其产品市场策略之间的关系依赖于代理问题的性质、不确定性的来源及产品市场的特征等因素,企业的最优资本结构应该随这些因素的变化而变化.     

从殖民和后殖民的角度看现代性问题

全球范围内殖民主义体系的崩溃，使现代性具有了多义性和混乱性。这证明了西方现代性本身存在着矛盾性和含混性，也说明了西方现代性的对立面——反殖民主义和现代性的效颦者——更加深了现代性本身的矛盾性和含混性，表现出对资本主义工业（或后工业）社会所设想的现代文明的质疑与抗议。     

铁磁性金属簿膜磁特性的研究

讨论了铁磁性金属薄膜中的各向弄性磁阻效应。通过对晶体结构分析和实验验证,提出了一种假设:在外磁场作用下,产生了原子对的方向有序化,导致感生磁各向异性,并使晶体织构消失。根据对5种样品的实测数据,讨论了薄膜的动态磁化过程。     

发生认识论的哲学来源

皮亚杰的发生认识论并不是一个纯粹的发展心理学理论,而是一个关于认知的结构及其发生与发展的理论。发生认识论的建立有其深厚的哲学根源:它是在批判传统认识论中的经验主义和理性主义的基础上建立起来的。皮亚杰看到,无论是经验主义方法,还是理性主义方法对于认知的结构及其发生与发展的解释都是片面的,因为前者忽视了结构,后者假设了结构而没有注意到结构发展的自然进程。皮亚杰在对两者辨证综合的基础上,提出“发生学的结构主义”,指出认识的发生与发展是因为我们作为生物先天地就包含着这样的结构,而且是因为我们作为生物对结构进行主动建构的结果。     

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.