Observation of Externalizing Behavior During a Twin-Friend Discussion Task

SUMMARY

In the last decade, numerous collaborations between developmentalists and behavior geneticists have extended developmental theories to genetically informative samples. This study integrates the approaches used by behavior geneticists and environmental researchers to further our understanding of the etiology of children's externalizing behavior. First, genetic and environmental influences on externalizing behavior are reviewed and studies using data from parent reports, self-reports, teacher reports, public records, and observation are described. Second, observational data from a middle-childhood twin sample are presented. Results suggest significant dominant genetic effects on observed twin negative behavior during a friend interaction (N= 148 twin pairs). In addition, nonshared environmental effects were substantial; when controlling for the coparticipant's behavior, nonshared environment was the sole source of variation. Context and method effects are discussed.     

基于适应性内容呈现的网络课程设计开发

指出了学生特点和差异性在网络课程开发中的重要性，提出了在网络课程中应根据学生学习风格提供相适应的内容呈现方式的观点．探讨了基于适应性内容呈现的网络课程的设计开发过程，并以《微机原理与接口技术》网络课程的开发为例阐述了其实现方法和注意事项．     

Cancer Risk Estimation for Mixtures of Coal Tars

Two-year chronic bioassays were conducted by using B6C3F1 female mice fed several concentrations of two different mixtures of coal tars from manufactured gas waste sites or benzo(a)pyrene (BaP). The purpose of the study was to obtain estimates of cancer potency of coal tar mixtures, by using conventional regulatory methods, for use in manufactured gas waste site remediation. A secondary purpose was to investigate the validity of using the concentration of a single potent carcinogen, in this case benzo(a)pyrene, to estimate the relative risk for a coal tar mixture. The study has shown that BaP dominates the cancer risk when its concentration is greater than 6,300 ppm in the coal tar mixture. In this case the most sensitive tissue site is the forestomach. Using low-dose linear extrapolation, the lifetime cancer risk for humans is estimated to be: Risk < 1.03 × 10⁻⁴ (ppm coal tar in total diet) + 240 × 10⁻⁴ (ppm BaP in total diet), based on forestomach tumors. If the BaP concentration in the coal tar mixture is less than 6,300 ppm, the more likely case, then lung tumors provide the largest estimated upper limit of risk, Risk < 2.55 × 10⁻⁴ (ppm coal tar in total diet), with no contribution of BaP to lung tumors. The upper limit of the cancer potency (slope factor) for lifetime oral exposure to benzo(a)pyrene is 1.2 × 10⁻³ per μg per kg body weight per day from this Good Laboratory Practice (GLP) study compared with the current value of 7.3 × 10⁻³ per μg per kg body weight per day listed in the U.S. EPA Integrated Risk Information System.     

论网络时代大学图书馆的服务

本文首先探讨了在网络时代大学图书馆的传统服务模式已经面临危机,然后讨论了面临危机的同时,也带来了新的发展机遇,最后提出了一些新的网络服务方式.     

网络化条件下图书馆服务功能与服务方式探析

本文论述了网络化条件下图书馆的服务功能与方式发生的巨大变化,同时提出了对图书馆员的新的素质要求.     

Traffic regulation with single- and dual-homed ISPs under a percentile-based pricing policy

We investigate how a customer (an enterprise or a large organization), when facing a percentile-based pricing policy, can optimally balance the Internet access cost and the traffic buffering delay penalty by traffic regulation. The problem is referred to as the Optimal Traffic Regulation (OTR) problem. Solutions to various cases of the OTR problem are provided. For a customer with a single-homed ISP, we present optimal solutions to the OTR problem based on dynamic programming for the offline case with a known traffic demand pattern. A real-time traffic scheduling algorithm is proposed to deal with the online case where the traffic demands are different from a given demand pattern. We further extend the dynamic programming model to the case of dual-homed ISPs. Experimental results on the data from an Internet trace confirm the effectiveness of our solutions. Part of the results has been presented in the First International Conference on Scalable Information Systems.     

Reconceptualizing and expanding the positive feedback network effects model: A case study

During the 1980s, economists developed the concept of positive network effects and switching costs as the key dynamics of de facto standards competition. They concluded that a positive feedback loop usually “tips” a market to the standard with the most users and complementary assets. While recent scholars have acknowledged that not all markets tip, and suggested some possible limitations on this phenomena, these limitations have not been integrated systematically into a model for competition in these industries. Using examples drawn from the standards contests of the past 20 years, this case study develops an integrated model for competition in these industries.     

A Design Theory Approach to Building Strategic Network‐Based Customer Service Systems*

Customer service is a key component of a firm's value proposition and a fundamental driver of differentiation and competitive advantage in nearly every industry. Moreover, the relentless coevolution of service opportunities with novel and more powerful information technologies has made this area exciting for academic researchers who can contribute to shaping the design and management of future customer service systems. We engage in interdisciplinary research—across information systems, marketing, and computer science—in order to contribute to the service design and service management literature. Grounded in the design‐science perspective, our study leverages marketing theory on the service‐dominant logic and recent findings pertaining to the evolution of customer service systems. Our theorizing culminates with the articulation of four design principles. These design principles underlie the emerging class of customer service systems that, we believe, will enable firms to better compete in an environment characterized by an increase in customer centricity and in customers' ability to self‐serve and dynamically assemble the components of solutions that fit their needs. In this environment, customers retain control over their transactional data, as well as the timing and mode of their interactions with firms, as they increasingly gravitate toward integrated complete customer solutions rather than single products or services. Guided by these design principles, we iterated through, and evaluated, two instantiations of the class of systems we propose, before outlining implications and directions for further cross‐disciplinary scholarly research.     

关于对网络时代下计算机审计的思考

21世纪是信息技术的时代。随着经济的发展及电算化在会计业务中的广泛应用,审计工作的对象、审计范围、审计线索等基本的审计要素都发生了巨大变化,因此,开展计算机审计,实施审计信息化是社会信息化的必然。     

网络教学中大学英语教师的角色定位

网络教学为教育带来了新的机遇和挑战.传统的教师角色已不再适应教育发展的新特点.大学英语教师要以建构主义理论为基础,积极转变观念,扮演好在新的教学模式下大学英语教师应扮演的角色,即教学过程的组织者、启发者、引导者,课程教学的设计者、开发者和研究者,交互式学习中的合作者,以及个性化教学的执行者.