A location analysis approach for military maintenance scheduling with geographically dispersed service areas

This research uses a two-stage maximal covering location problem (MCLP) model to develop Inter continental ballistic missile (ICBM) maintenance schedules for the US Air Force. Solutions are compared to actual missile maintenance activities accomplished at F. E. Warren Air Force Base (AFB), Wyoming in May 2005. Sensitivity analysis is performed to determine the impact of altering security response times and the number of security patrol areas on the quality of daily maintenance schedules and personnel usage. Results indicate marked improvement over traditional Air Force scheduling methods. In addition sensitivity analysis identifies the levels at which the quality and quantity of maintenance performance is impacted.     

Calibration of FISK, an Invasiveness Screening Tool for Nonnative Freshwater Fishes

Adapted from the weed risk assessment (WRA) of Pheloung, Williams, and Halloy, the fish invasiveness scoring kit (FISK) was proposed as a screening tool for freshwater fishes. This article describes improvements to FISK, in particular the incorporation of confidence (certainty/uncertainty) ranking of the assessors' responses, and reports on the calibration of the score system, specifically: determination of most appropriate score thresholds for classifying nonnative species into low-, medium-, and high-risk categories, assessment of the patterns of assessors' confidences in their responses in the FISK assessments. Using receiver operating characteristic (ROC) curves, FISK was demonstrated to distinguish accurately (and with statistical confidence) between potentially invasive and noninvasive species of nonnative fishes, with the statistically appropriate threshold score for high-risk species scores being ≥19. Within the group of species classed as high risk using this new threshold, a "higher risk" category could be visually identified, at present consisting of two species (topmouth gudgeon Pseudorasbora parva and gibel carp Carassius gibelio ). FISK represents a useful and viable tool to aid decision- and policymakers in assessing and classifying freshwater fishes according to their potential invasiveness.     

The Effect of Expected Income on Individual Migration Decisions

This paper develops a tractable econometric model of optimal migration, focusing on expected income as the main economic influence on migration. The model improves on previous work in two respects: it covers optimal sequences of location decisions (rather than a single once‐for‐all choice) and it allows for many alternative location choices. The model is estimated using panel data from the National Longitudinal Survey of Youth on white males with a high‐school education. Our main conclusion is that interstate migration decisions are influenced to a substantial extent by income prospects. The results suggest that the link between income and migration decisions is driven both by geographic differences in mean wages and by a tendency to move in search of a better locational match when the income realization in the current location is unfavorable.     

Qipao： Traditional Elegance Reinvents Itself In Modern Chinese Fashion

It was with some trepidation that I first went to teach in China, in 2004.All my information about China had come from old newsreel films. Basically,I was expecting a drab, black and white place where people queued to use the local telephone.     

Modeling the Niger Delta Insurgency

Nigeria's oil guarantees its role in the global economy; however, the state's overwhelming weaknesses perpetuate a high level of volatility vis-à-vis the potential for an immediate disruption of the national, regional, and global environment. This study presents a current qualitative analysis of Nigeria to produce a model that characterizes current conditions in the state and the state response to the nefarious acts in the delta region. This model will serve as a baseline for a significant iteration of the model that reflects the delta region counter-insurgency at various levels of strength: a what-if scenario of the region with an increase of state security over southern separatists, insurgents seeking to gain control of the oil assets. The conjectured model serves to inform/educate decision and policy makers in developing proactive, effective strategies to counter existent and potential threats in the Niger Delta.     

Vertical cost information sharing in a supply chain with value-adding retailers

We consider a supply chain consisting of one supplier and two value-adding heterogeneous retailers. Each retailer has full knowledge about his own value-added cost structure that is unknown to the supplier and the other retailer. Assuming there is no horizontal information sharing between two retailers, we model the supply chain with a three-stage game-theoretic framework. In the first stage each retailer decides if he is willing to vertically disclose his private cost information to the supplier. In the second stage, given the information he has about the retailers, the supplier announces the wholesale price to the retailers. In response to the wholesale price, in the third stage, the retailers optimize their own retail prices and the values added to the product, respectively. Under certain conditions, we prove the existence of equilibrium prices and added values. Furthermore, we obtain the condition under which both retailers are unwilling to vertically share their private information with the supplier, as well as the conditions under which both retailers have incentives to reveal their cost information to the supplier, thus leading to a win–win situation for the whole supply chain.     

Environmental ethics for social work: Social work's responsibility to the non‐human world

Gray M, Coates J. Environmental ethics for social work: Social work's responsibility to the non‐human world This lead article in this Special Issue begins discussion on an environmental ethics for social work and raises arguments as to whether and, if so, why social workers have duties, obligations, responsibilities and commitments to the non‐human world. It provides an overview of the field of environmental ethics in searching for a moral stance to affirm an environmental social work. To what extent should social workers engage in fundamental geopolitical issues concerned with climate change, global warming, environmental degradation, pollution, chemical contamination, sustainable agriculture, disaster management, pet therapy, wilderness protection and so on and, if so, why and how? Are these issues incidental and peripheral and only of concern when they impact upon humans or do social workers have a responsibility beyond human interests? What is the significance of the ‘non‐human’ for social work? The article explores the terrain of the burgeoning field of environmental ethics to determine whether convincing ethical grounds for environmental social work might be found beyond hortatory claims of what the profession ought to be doing to address environmental concerns.     

Confidence intervals for finite difference solutions

Although applications of Bayesian analysis for numerical quadrature problems have been considered before, it is only very recently that statisticians have focused on the connections between statistics and numerical analysis of differential equations. In line with this very recent trend, we show how certain commonly used finite difference schemes for numerical solutions of ordinary and partial differential equations can be considered in a regression setting. Focusing on this regression framework, we apply a simple Bayesian strategy to obtain confidence intervals for the finite difference solutions. We apply this framework on several examples to show how the confidence intervals are related to truncation error and illustrate the utility of the confidence intervals for the examples considered.     

冒险成就的电信巨头

从任何一个角度看,全球无线手机通讯行业都在快速逼近危机的边缘。全世界已经有50多个国家的手机用户数量超过其实际人口数量。即使是在工业化国家中手机人均拥有率较低的美国,在用的手机数量也超过了2.7亿部（市场渗透率接近于90％）。今天,随着无线通讯市场的日益萎缩,