A frequency domain comparison of estimation methods for gaussian fields

This paper demonstrates that well-known parameter estimation methods for Gaussian fields place different emphasis on the high and low frequency components of the data. As a consequence, the relative importance of the frequencies under the objective of the analysis should be taken into account when selecting an estimation method, in addition to other considerations such as statistical and computational efficiency. The paper also shows that when noise is added to the Gaussian field, maximum pseudolikelihood automatically sets the smoothing parameter of the model equal to one. A simulation study then indicates that generalised cross-validation is more robust than maximum likelihood un-

der model misspecification in smoothing and image restoration problems. This has implications for Bayesian procedures since these use the same weightings of the frequencies as the likelihood.     

Automatic locally adaptive smoothing for tree-based set estimation

Tree-based methods similar to CART have recently been utilized for problems in which the main goal is to estimate some set of interest. It is often the case that the boundary of the true set is smooth in some sense, however tree-based estimates will not be smooth, as they will be a union of ‘boxes’. We propose a general methodology for smoothing such sets that allows for varying levels of smoothness on the boundary automatically. The method is similar to the idea underlying support vector machines, which is applying a computationally simple technique to data after a non-linear mapping to produce smooth estimates in the original space. In particular, we consider the problem of level-set estimation for regression functions and the dyadic tree-based method of Willett and Nowak [Minimax optimal level-set estimation, IEEE Trans. Image Process. 16 (2007), pp. 2965–2979].     

Comments

In this paper we compare Bartlett-corrected, bootstrap, and fast double bootstrap tests on maximum likelihood estimates of cointegration parameters. The key result is that both the bootstrap and the Bartlett-corrected tests must be based on the unrestricted estimates of the cointegrating vectors: procedures based on the restricted estimates have almost no power. The small sample size bias of the asymptotic test appears so severe as to advise strongly against its use with the sample sizes commonly available; the fast double bootstrap test minimizes size bias, while the Bartlett-corrected test is somehow more powerful.     

如何发现DNA是生命的遗传物质

从核酸的发现到DNA双螺旋结构模型建立历时80余年,人类最终确认了DNA是生命的遗传物质,解决了一个生命科学研究中极其关键的重大问题。因此,对此段历史的研究具有重要意义。全面回顾此间发生的对揭示DNA的结构和功能具有重要影响的事件,包括米歇尔发现核酸、列文提出＂四核苷酸假说＂、格里菲斯等人的转化实验、査伽夫提出碱基配对规律,以及沃森和克里克建立DNA双螺旋结构模型,在此基础上阐述人类发现DNA是遗传物质的研究历程,进而探讨科学研究的规律。     

Linking aggregate production planning with marketing pricing decisions

In this paper, we link production planning decisions to marketing decisions that involve the price of product groups. The focus of this paper is the development of a closed-loop procedure for aggregate production planning and pricing. We seek to satisfy uncertain demand while minimizing total costs that include material, labour, and inventory holding costs. The procedure is useful for variable demand to update short-term aggregate plans.     

Electile Dysfunction

This essay combines Burke's burlesque frame and Jamieson's double binds to create a hybrid gendered theory for rhetorically analyzing the aggressive sexualization of 2008 United States vice presidential candidate Sarah Palin. The essay develops our theory titled the “burlesque binds” and explicates a specific form of a burlesque bind: the “MILF frame.” Palin's aggressively sexualized representation was united under the crass acronym MILF, which stands for “Mom I'd Like to Fuck.” The MILF frame emphasized Palin's feminine qualities, positioning her as a “trophy vice” with no political acumen, and highlighted her masculine behaviors, but deflated them through sexual objectification. The unification of the binds and burlesque theories reveals how Palin's role as a social actor was not simply circumscribed but shut down: she was deemed unfit by both masculine and feminine standards, by both public and private sphere conventions. Although Sarah Palin has arguably been the most prevalent subject of the political MILF frame, our essay catalogues other instances of female political leaders experiencing this type of symbolic degradation, suggesting the MILF frame's vast influence.     

移动通信单向收费定价策略研究

随着移动通信业务的飞速发展,其收费模式和定价策略为世界各国所关注。本文从中国电信产业现状出发,对移动通信单向收费定价策略进行研究,结果表明:①网络外部性对移动通信市场有福利增加效果;②产业发展早期,可采取呼叫付费原则发展移动通信;③产业发展后期,可采取分离付费原则增加社会福利。     

企业财务危机预警双基点距离比值法

本文介绍了国内外主要企业财务危机预警模型,对模型的空间几何意义进行解释。提出了企业财务危机预警双基点距离比值模型,该模型采用非线性方法对危机企业与非危机企业的财务指标集合进行分割。用112例样本实证,预警识别率达到92.8%。     

浅谈社会发展的双重结构模式

探索适合于研究发展中国家的社会结构模式 ,从而突破单一结构模式的现代化理论的局限性是本文的主旨。运用分析和比较的方法 ,指出社会结构具有多重性、多层次性 ,发展中国家的社会结构具有独特性。发展中国家只有形成社会表层结构与社会深层结构良性互动的模式 ,才能保持结构张力 ,焕发社会活力 ,促进社会发展。     

"微机原理与应用"课程的双语教学尝试

文章结合对非计算机类本科"微机原理与应用"课程几年的教学实践以及首次对该课程双语教学的尝试,讲述了一些如何提高教学质量、搞好双语教学的经验和方法.