Skin Cancer and Inorganic Arsenic: Uncertainty-Status of Risk

The current U.S. EPA standard for inorganic arsenic in drinking water is 50 ppb (μg/L), dating to the National Interim Primary Drinking Water Regulation of 1976. The current EPA risk analysis predicts an increased lifetime skin cancer risk on the order of 3 or 4 per 1000 from chronic exposure at that concentration. Revision of the standard to only a few ppb, perhaps even less than 1 ppb, may be indicated by the EPA analysis to reduce the lifetime risk to an acceptable level. The cost to water utilities, and ultimately to their consumers, to conform to such a large reduction in the standard could easily reach several billion dollars, so it is particularly important to assess accurately the current risk and the risk reduction that would be achieved by a lower standard. This article addresses the major sources of uncertainty in the EPA analysis with respect to this objective. Specifically, it focuses on uncertainty and variability in the exposure estimates for the landmark study of Tseng and colleagues in Taiwan, analyzed using a reconstruction of the their exposure data. It is concluded that while the available dataset is suitable to establish the hazard of skin cancer, it is too highly summarized for reliable dose-response assessment. A new epidemiologic study is needed, designed for the requirements of dose-response assessment.     

当代媒介问题的人种学视野

媒介研究的价值在于能够引发许多陈旧但是重要的社会理论问题。将媒介纳入现代性叙事，既源于媒介对于现代性的历史和现实的意义，也是对国际媒介研究的一种回应。基于中国媒介主导群体的人种学分析，为媒介理论突破带来了新的视野。     

Ecological restoration volunteers: the benefits of participation

There is an international volunteer movement to protect and restore sensitive natural landscapes. In Illinois alone, almost 40,000 acres of rare prairie, oak savanna, wetlands and woodland ecosystems in urban and suburban communities are monitored and managed by volunteers. As natural habitats disappear or become degraded worldwide, it is increasingly important to understand how a personal involvement with nature, in the form of restoration, benefits the individual as well as aiding in species and ecosystem survival. This study examined the satisfactions that volunteers derive from prairie restoration in the Chicago metropolitan area. Questionnaire responses from 263 volunteers indicate that volunteers experience high levels of many different satisfactions. Tenure, frequency and extent of involvement in restoration were used to predict restoration satisfactions, life satisfaction and life functioning. Implications for recruiting and sustaining volunteer involvement in restoration efforts are discussed.     

Gender,Sibship Structure,and Educational Inequality in Taiwan: Son Preference Revisited

This study examines how sibship characteristics affect educational attainment in Taiwan. Using a multilevel analysis of a sibling sample of 12,715 observations from 3,001 families drawn from a national survey, we investigate the effects of family size, sibship density, birth‐order rank, and sibship gender composition. The results support the argument that the effect of son preference on intrafamily educational inequality is conditional on family resources. We also find, however, that male firstborns, who are the ultimate inheritors of paternal authority in Chinese families, have additional leverage in the sibling competition for family resources. The privilege for firstborns does not extend to daughters. Therefore, we argue that culturally defined norms regarding seniority and gender help shape intrafamily resource allocation in Chinese society.     

F_{3}-domination problem of graphs

Given a graph \(G\) and a set \(S\subseteq V(G),\) a vertex \(v\) is said to be \(F_{3}\) -dominated by a vertex \(w\) in \(S\) if either \(v=w,\) or \(v\notin S\) and there exists a vertex \(u\) in \(V(G)-S\) such that \(P:wuv\) is a path in \(G\) . A set \(S\subseteq V(G)\) is an \(F_{3}\) -dominating set of \(G\) if every vertex \(v\) is \(F_{3}\) -dominated by a vertex \(w\) in \(S.\) The \(F_{3}\) -domination number of \(G\) , denoted by \(\gamma _{F_{3}}(G)\) , is the minimum cardinality of an \(F_{3}\) -dominating set of \(G\) . In this paper, we study the \(F_{3}\) -domination of Cartesian product of graphs, and give formulas to compute the \(F_{3}\) -domination number of \(P_{m}\times P_{n}\) and \(P_{m}\times C_{n}\) for special \(m,n.\)      

A Bayesian predictive approach to determining the number of components in a mixture distribution

This paper describes a Bayesian approach to mixture modelling and a method based on predictive distribution to determine the number of components in the mixtures. The implementation is done through the use of the Gibbs sampler. The method is described through the mixtures of normal and gamma distributions. Analysis is presented in one simulated and one real data example. The Bayesian results are then compared with the likelihood approach for the two examples.     

Scheduling of Multi‐skilled Staff Across Multiple Locations

We address the problem of assigning airline customer service agents (CSAs) to tasks related to departing flights, such as selling tickets and collecting boarding cards, at an international terminal of a large airport. The airline specifies minimum and target levels of staff and required (or desired) types and levels of skills for each location in each time period. The assignment problem is complicated by staff heterogeneity, time required for moves between locations, and lunch and rest‐break requirements. We present a mixed‐integer formulation that considers both staffing shortages and skills mismatches and show that the problem is NP‐hard. We derive valid inequalities that tighten the bounds within a branch‐and‐cut procedure, enabling us to obtain near‐optimal solutions for problems of realistic size very quickly. We also present a generalization to simultaneously optimize shift starting times and task assignments, which can aid in longer term workforce planning. Finally, we utilize our procedure to obtain managerial insights regarding the benefits of flexibility derived from more highly skilled staff, allowing more frequent moves, and choices of shift starting times. We also demonstrate the benefits of our procedure vs. a heuristic that mimics what an experienced scheduler might choose.     

宋代河北书院述论

对于宋代河北书院的研究,从以往的3所扩充到5所,并对5所书院的发展进行了分析,总结了书院师生体现出来的理学家教育理念及方法.对比全国其他区域书院发展的状况,宋代河北的书院发展相对薄弱,与古代后期相较相对滞后,究其原因是战争的影响、行政建制问题以及河北地区遭受的蝗灾、洪灾等方面的影响造成的.     

Control charts for fraction nonconforming in a bivariate binomial process

Many multivariate quality control techniques are used for multivariate variable processes, but few work for multivariate attribute processes. To monitor multivariate attributes, controlling the false alarms (type I errors) and considering the correlation between attributes are two important issues. By taking into account these two issues, a new control chart is presented to monitor a bivariate binomial process. An example is illustrated for the proposed method. To evaluate the performance of the proposed method, a simulation study is conducted to compare the results with those using both the multivariate np chart and skewness reduction approaches. The results show that the correlation is taken into account in the designed chart and the overall false alarm is controlled at the nominal value. Moreover, the process shift can be quickly detected and the variable that is responsible for a signal can be determined.     

Attribute Control Chart for Multivariate Poisson Distribution

In this study, a control chart is constructed to monitor multivariate Poisson count data, called the MP chart. The control limits of the MP chart are developed by an exact probability method based on the sum of defects or non conformities for each quality characteristic. Numerical examples are used to illustrate the MP chart. The MP chart is evaluated by the average run length (ARL) in simulation. The result indicates that the MP chart is more appropriate than the Shewhart-type control chart when the correlation between variables exists.