Bayesian discrete latent spatial modeling of crack initiation in orthopaedic hip replacement bone cement

In this paper, we propose a spatial model for the initiation of cracks in the bone cement of hip replacement specimens. The failure of hip replacements can be attributed mainly to damage accumulation, consisting of crack initiation and growth, occurring in the cement mantle that interlocks the hip prosthesis and the femur bone. Since crack initiation is an important factor in determining the lifetime of a replacement, the understanding of the reasons for crack initiation is vital in attempting to prolong the life of the hip replacement. The data consist of crack location coordinates from five laboratory experimental models, together with stress measurements. It is known that stress plays a major role in the initiation of cracks, and it is also known that other unmeasurable factors such as air bubbles (pores) in the cement mantle are also influential. We propose an identity-link spatial Poisson regression model for the counts of cracks in discrete regions of the cement, incorporating both the measured (stress), and through a latent process, any unmeasured factors (possibly pores) that may be influential. All analysis is carried out in a Bayesian framework, allowing for the inclusion of prior information obtained from engineers, and parameter estimation for the model is done via Markov chain Monte Carlo techniques.     

ARFIMA processes and outliers: a weighted likelihood approach

In this paper, we consider the problem of robust estimation of the fractional parameter, d, in long memory autoregressive fractionally integrated moving average processes, when two types of outliers, i.e. additive and innovation, are taken into account without knowing their number, position or intensity. The proposed method is a weighted likelihood estimation (WLE) approach for which needed definitions and algorithm are given. By an extensive Monte Carlo simulation study, we compare the performance of the WLE method with the performance of both the approximated maximum likelihood estimation (MLE) and the robust M-estimator proposed by Beran (Statistics for Long-Memory Processes, Chapman & Hall, London, 1994). We find that robustness against the two types of considered outliers can be achieved without loss of efficiency. Moreover, as a byproduct of the procedure, we can classify the suspicious observations in different kinds of outliers. Finally, we apply the proposed methodology to the Nile River annual minima time series.     

也谈简体字

在政治更迭、文化变迁的大叙事中，小小的文字变化最能体现大时代的风貌。古有始皇帝威权下的“书同文”，今有上世纪五十年代初旨在“汉字拉丁化”的“文字简化运动”。简化字与繁体字争议的背后，是政治激进主义与文化保守主义的思想交锋，或者说是中华历史文化断裂与传承的别一选择。周清泉先生关于“汉字简化方案”实施中的管见，因于当时话语权被肆意剥夺而无处表达，本刊编发该文，一是提供关于汉字简化的反思与总结，二是彰显学人发表独立见解的历史进步。     

Girlz II women: Age‐grading,language change and stylistic variation

Informed by abstract models of language change or stability over time, we present a longitudinal study of two African American females, first interviewed as teenagers, and re‐recorded twenty years later. As teenagers, they used morpho‐syntactic features of AAVE voraciously. But as working adults, these women distance themselves from their teenage activities and social networks, and display a considerably reduced vernacular usage that accords with their articulated concern to get ahead. The diachronic interpretation that best characterizes their transformation is age‐grading rather than generational change, since change at the individual level is accompanied by stability at the community level. The picture is complicated by intermediate recordings showing that one of the speakers is a stylistic chameleon, capable since her teenage years of varying copula absence rates depending on addressee, topic, and projected persona. But the age‐grading interpretation of change at the individual level remains valid based on the evidence of her reduced use of habitual be2, and third singular present tense –s absence. The case highlights the importance of paying more attention to stylistic variation and including more than two time points in sociolinguistic studies of change in real and apparent time.     

从第27届男篮亚锦赛中国队失利看亚洲篮球新格局

第27届男篮亚锦赛中国队遭遇惨败,年龄结构不合理、攻防两端不平衡、球员的位置技术基础欠缺、主帅与球员磨合期短等因素,是导致中国男篮成绩跌入谷底的主要原因.反观冠军伊朗队,其强势崛起值得思考,亚洲篮球新格局已经形成.     

马克思主义中国化研究述评

马克思主义中国化的研究经过了多年的发展取得了一系列喜人的理论建树,特别是研究的重点不断拓宽,在基本内容、内在关系等方面颇为深入,呈现出了全方位、多层次、宽领域的特点.同时研究焦点的视角不断衍伸, 但仍在诸多方面存在着盲点,而这正是必须深入耕犁的领域,我们也试图从思想下乡、范式建构、信仰研究等方面突破盲点,以期为马克思主义中国化的新发展尽绵薄之力.     

Demand Systems Estimation With Microdata: A Censored Regression Approach

Demand systems estimation increasingly makes use of household-level microdata, mainly to measure the effects of demographic variables. Data based on these household-expenditure surveys present a major estimation problem. For any given household, many of the goods have zero consumption, implying a censored dependent variable. Techniques which do not take this censored dependent variable into account will yield biased results. We utilize a censored regression approach that is computationally simple, consistent, and asymptotically efficient. The results are then presented and compared with those obtained using an uncensored technique.     

Central Limit Theorem approximations for the number of runs in Markov-dependent binary sequences

We consider Markov-dependent binary sequences and study various types of success runs (overlapping, non-overlapping, exact, etc.) by examining additive functionals based on state visits and transitions in an appropriate Markov chain. We establish a multivariate Central Limit Theorem for the number of these types of runs and obtain its covariance matrix by means of the recurrent potential matrix of the Markov chain. Explicit expressions for the covariance matrix are given in the Bernoulli and a simple Markov-dependent case by expressing the recurrent potential matrix in terms of the stationary distribution and the mean transition times in the chain. We also obtain a multivariate Central Limit Theorem for the joint number of non-overlapping runs of various sizes and give its covariance matrix in explicit form for Markov dependent trials.     

The Micro-Formation Mechanism of Trade Conflicts between Large Developing Countries: India’s Anti-dumping Action against China

Abstract

Employing Grossman and Helpman’s “protection for sale” model, this article uses data on anti-dumping actions from 1999 to 2009 to perform a quantitative analysis of factors influencing India’s determinations of anti-dumping duties against China, and reveals the micro-formation mechanism of economic conflicts between China and India. We find that the political power of India’s anti-dumping plaintiffs markedly increases the tariff level of its final determinations and that the relationship between the import penetration ratio and duty rates depends upon whether the plaintiffs are politically organized. Further, there is a significant positive correlation between India’s anti-dumping duty rates and its unfavorable trade balance with China. This indicates that in determining anti-dumping duties, Indian authorities are clearly influenced by the political clout of their domestic interest groups. They are also motivated by the desire to keep down China and gain the upper hand in the face-off between the “dragon and the elephant.”     

Sums of weighted spacings and a test for the logistic distribution

A simple proof for a theorem of Csörgö and Révész (1981b and 1984) concerning sums of weighted spacings is given, The conditions of the theorem are relaxed. As an application, a goodness-of-fit test for the logistic distribution is proposed. The percentage points of the proposed test statistic are obtained by a simulation experiment.