The Economic Efficiency of Sampling Size: The Case of Beef Trim

The economically optimal sample size in a food safety test balances the marginal costs and marginal benefits of increasing the sample size. We provide a method for selecting the sample size when testing beef trim for Escherichia coli O157:H7 that equates the averted costs of recalls and health damages from contaminated meats sold to consumers with the increased costs of testing while allowing for uncertainty about the underlying prevalence rates of contamination. Using simulations, we show that, in most cases, the optimal sample size is larger than the current sample size of 60 and, in some cases, it exceeds 120. Moreover, lots with a lower prevalence rate have a higher expected damage because contamination is more difficult to detect. Our simulations indicate that these lots have a higher optimal sampling rate.     

论欧·亨利文学作品中个性化人物的象征意义

欧·亨利作为美国短篇小说一代巨匠,在世界文坛拥有巨大影响力。究其根源,十分重要的一方面即在于其小说中人物创设个性化的同时被赋予了广泛而深邃的象征意义,让人感受到强大的震撼与共鸣。文章通过选取欧·亨利成名之作的四部小说中的四位个性化人物并加以分析,以深化学界对其作品中人物象征意义的探究。     

INFORMATION INTERDEPENDENCE: Keohane and Nye's complex interdependence in the information age

A well-known and respected attempt to theorize interdependence in the field of international relations is complex interdependence. In Power and Interdependence , Robert O. Keohane and Joseph S. Nye, Jr define interdependence as reciprocal effects among actors resulting from 'international transactions - flows of money, goods, people and messages across international boundaries'. Though much research has been done on the effects of interdependence on the first three, the flows of messages have been studied less often. Keohane and Nye addressed the issue in a 1998 article in Foreign Affairs , discussing changes in the global environment resulting from the information age which have had an impact on their ideas. This article proposes to go deeper into complex interdependence. The world is becoming increasingly 'information interdependent' and this essay is an attempt to apply the assumptions and concepts presented in complex interdependence to the information age. In the final analysis, complex interdependence complements research from the field of communications, that information flows should be understood as underlying mechanisms and processes that facilitate contextual understanding of issues. It maintains the integrity of the assumptions of complex interdependence, while adding an understanding of the nature of information and information flows.     

Estimating conditional tail expectation with actuarial applications in view

We develop statistical inferential tools for estimating and comparing conditional tail expectation (CTE) functions, which are of considerable interest in actuarial science. In particular, we construct estimators for the CTE functions, develop the necessary asymptotic theory for the estimators, and then use the theory for constructing confidence intervals and bands for the functions. Both parametric and non-parametric approaches are explored. Simulation studies illustrate the performance of estimators in various situations. Results are obtained under minimal assumptions, and the general Vervaat process plays a crucial role in achieving these goals.     

Considerations on group-wise identical designs for linear mixed models

We consider a general class of mixed models, where the individual parameter vector is composed of a linear function of the population parameter vector plus an individual random effects vector. The linear function can vary for the different individuals. We show that the search for optimal designs for the estimation of the population parameter vector can be restricted to the class of group-wise identical designs, i.e., for each of the groups defined by the different linear functions only one individual elementary design has to be optimized. A way to apply the result to non-linear mixed models is described.     

从12SrRNA部分基因序列探讨鳄的系统发生关系

本文用常规方法测定了雅卡凯门鳄（caiman yacane）、新几内亚鳄（crocodylus novaeguineae）等2种鳄类的约400bp的mtDNA12SrRNA基因片段的部分序列，所测序列与GenBank中的其他18种鳄类的12SrRNA基因相应片段同源序列一起经Clustal X1．8软件进行比对，并以乌龟（chinemys reevesii）为外群，用ClustalX（1．8），Mega2软件以及paup软件将这20种鳄的12SrRNA基因部分序列进行比对后构建了20种鳄的进化关系树，并分别用NJ树，MP树探讨它们之间的系统发生关系。其结果显示：食鱼鳄属Gavialis与马来假食鱼鳄属Tomistoma的亲缘关系较近，构成姐妹群并位于鳄科分支的基部。非洲窄吻鳄（Crocodylus cataphractus）与骨喉鳄（Osteolaemus retraspis）形成姐妹群，它们的亲缘关系比与其它真鳄类的关系更近，赞同非洲窄吻鳄应从鳄属中独土出来归属于长吻鳄属Mecistops的观点，因此鳄科包括鳄属、骨喉鳄属和长吻鳄属，它们的关系为（鳄属（骨喉鳄属，长吻鳄属））。鼍科4属中凯门鳄属与黑鳄属关系最近，接下来的是古鳄属、鼍属，而且鼍属是鼍科中起源最早的类群。扬予鳄（Alligator sinensis）与密河鳄（Alligator mississippiensis）较近的亲缘关系得到支持，但它们并没有形成姐妹群关系。     

制革铬鞣废水中铬(Ⅲ)的治理和回收利用

采用沉淀－双氧水氧化法，对制革铬鞣废水中铬（Ⅲ）的治理和回收利用进行了研究．该法对铬（Ⅲ）的回收率可达９２％，处理后废水澄清，无色，无味，稳定，ｐＨ值８～８．５．     

H2O2与UV／TiO2协同体系光催化降解酸性品红的研究

采用高压汞灯为光源，考察了H2O2与UV／TiO2协同体系对酸性品红的降解效果。结果表明：H2O2提高了UV／TiO2光催化降解酸性品红的速率。同时，研究了影响纳米TiO2光催化降解酸性品红的主要影响因素。实验结果表明：初始PH值等于7时，光催化效率最佳；随着初始浓度的增加光催化降解效率降低；TiO2的最佳用量为0．2g/L。     

FROM MAIZE TO HAZE: AGRICULTURAL SHOCKS AND THE GROWTH OF THE MEXICAN DRUG SECTOR

Understanding how economic incentives affect illegal drug production is essential for crafting policies in response to the international drug trade. Policymakers typically face a choice between two strategies: targeting criminal groups via law enforcement, and offering producers incentives to engage in alternate activities. Yet, little is known about how the returns to alternate legal activities affect drug supply. We contribute to this literature by examining how shocks to legal commodity prices affect the drug trade in Mexico. Our analysis exploits exogenous movements in the Mexican maize price stemming from weather conditions in US maize‐growing regions, as well as exports of other major maize producers. Using data on over 2200 municipios spanning 1990–2010, we show that lower prices differentially increased the cultivation of both marijuana and opium poppies in municipios more climatically suited to growing maize. We also find impacts on downstream drug‐trade outcomes, including drug cartel operations and killings perpetrated by these groups. Our findings demonstrate that maize price changes contributed to the burgeoning drug trade in Mexico, and point to the violent consequences of an expanding drug sector.     

Understanding sex: the right to legal capacity to consent to sex

This article addresses the right to legal capacity to consent to sex of people with intellectual disabilities. Article 12 of the Convention on the Rights of Persons with Disabilities guarantees the right to legal capacity on an equal basis in all areas of life. This article discusses sex as an area of life in which people with intellectual disabilities are frequently not being granted legal capacity on an equal basis. The article examines current capacity to consent to sex law in Ireland, England and Wales in light of Article 12. It proposes an ‘agreement model’ as a potential alternative that would be Article 12 compliant.