Judicious order acceptance and order release in make-to-order manufacturing systems

This paper explores a two-stage input control system for fixed capacity make-to-order manufacturing systems (with heavy job tardiness penalties), that selectively accepts incoming orders and holds the accepted ones in a pre-shop queue prior to releasing them to the shop floor. Single-stage input control systems that only allow orders to be delayed in a pre-shop queue (i.e. they do not allow some orders to be rejected) have been previously investigated and found to negatively impact overall due-date performance. The hypothesis motivating this research is that judiciously rejecting a subset of incoming orders can prevent the order release queue from being overloaded when a surge of demand occurs. The input control system is evaluated via experiments using a discrete-event simulation model of a fixed capacity manufacturing system. The experiments reported here suggest that holding orders in the pre-shop queue does not improve due date performance, and that judiciously rejecting orders on its own is a viable alternative mechanism of input control that can deliver improved performance.     

Where You Lead,I Will Follow: Exploring Sibling Similarity in Brain and Behavior During Risky Decision Making

This exploratory study examined whether social learning increases similarity in adolescent siblings’ behavior and neural patterns during risky decision making. Participants included 86 adolescents (43 sibling dyads; younger siblings: M_age = 12.2 years; 22 females; older siblings: M_age = 14.6 years; 20 females) who completed questionnaires, and a decision‐making task during an fMRI scan. Younger siblings became more similar to their older siblings’ risky decision making after observing their older sibling take risks). Younger siblings who reported greater modeling of their older sibling, and less differentiation from them, showed increased neural similarity to their older siblings in the ventromedial prefrontal cortex, and the right anterior insula and ventral striatum, respectively. These findings highlight siblings as salient social agents in how adolescents process risky decision making.     

Retailer Transshipment versus Central Depot Allocation for Supply Network Design

We consider a supply chain structure with shipments from an external warehouse directly to retailers and compare two enhancement options: costly transshipment among retailers after demand has been realized vs. cost‐free allocation to the retailers from the development of a centralized depot. Stochastic programming models are developed for both the transshipment and allocation structures. We study the impact of cost parameters and demand coefficient of variation on both system structures. Our results show an increasing convex relationship between average costs and demand coefficient of variation, and furthermore that this increase is more pronounced for the allocation structure. We employ simulation and nonlinear search techniques to computationally compare the cost performance of allocation and transshipment structures under a wide range of system parameters such as demand uncertainty and correlation; lead times from the external warehouse to retailers, from warehouse to central depot, and from depot to retailers; and transshipment, holding, and penalty costs. The transshipment approach is found to outperform allocation for a broad range of parameter inputs including many situations for which transshipment is not an economically sound decision for a single period. The insights provided enable the manager to choose whether to invest in reducing lead times or demand uncertainty and assist in the selection of investments across identical and nonidentical retailers.     

Major League Baseball Players' Life Expectancies*

Objective. We examine the importance of anthropometric and performance measures, and age, period, and cohort effects in explaining life expectancies among major league baseball (MLB) players over the past century. Methods. We use discrete time hazard models to calculate life tables with covariates with data from Total Baseball, a rich source of information on all players who played in the major league. Results. Compared to 20‐year‐old U.S. males, MLB players can expect almost five additional years of life. Height, weight, handedness, and player ratings are unassociated with the risk of death in this population of highly active and successful adults. Career length is inversely associated with the risk of death, likely because those who play longer gain additional incomes, physical fitness, and training. Conclusions. Our results indicate improvements in life expectancies with time for all age groups and indicate possible improvements in longevity in the general U.S. population.     

Using age and spatial flow structures in the indirect estimation of migration streams

This article outlines a formal model-based approach for inferring interregional age-specific migration streams in settings where such data are incomplete, inadequate, or unavailable. The estimation approach relies heavily on log-linear models, using them to impose some of the regularities exhibited by past age and spatial structures or to combine and borrow information drawn from other sources. The approach is illustrated using data from the 1990 and 2000 U.S. and Mexico censuses.     

Bottleneck identification and ranking model for mine operations

Abstract

Mining has a long history of production and operations management. Considering the increasing complexity of reserves, declining metal grades, and worldwide price volatilities, mines have to operate more efficiently than ever. In recent years, companies have been adopting innovative solutions and technologies to reduce costs and remain competitive in the global market. Specifically, management of bottlenecks has been in the focus of the manufacturing industry for decades now. The mining industry has made significant advancements in process improvement tools using equipment, human, and asset tracking capabilities. However, to date, there is no holistic approach or system to identify and manage the bottleneck in the entire value chain of mining. This research proposes a new method to identify and rank the bottlenecks in a mine value chain. The method is applied in a coal mine and the results are presented in the case study.     

BACKLASH, THE MATRIX OF DOMINATION, AND LOG CABIN REPUBLICANS

This article focuses on Log Cabin Republicans, gay members of that political party who reject "queer' politics and "leftist' projects among lesbian and gay activists. We show that members' social class, race, age, and gender are as central to an understanding of Log Cabin politics as is their nonnormative sexuality. The case of the Log Cabin Republicans illustrates how the matrix of domination is reaffirmed in backlash rhetoric and related so-ciopolitical practices. It also shows that the gay community comprises multiple, divergent subgroups that make the boundaries between lesbigay and straight politics more or less ambiguous and fluid. Put differently, the Log Cabin Republicans illuminate the practical limits of identity politics.
Early in the twentieth century, a gay white middle-class male observed:
Not till our whole commercial system, with its barter and sale of human labor and human love for gain, is done away, and not till a whole new code of ideals and customs of life has come in, will women really be free. They must remember that their cause is also the cause of the oppressed laborer over the whole earth, and the laborer has to remember that his cause is theirs. (Carpenter 1911, p. 60)     

Nondrinker Mortality Risk in the United States

The literature has shown that people who do not drink alcohol are at greater risk for death than light to moderate drinkers, yet the reasons for this remain largely unexplained. We examine whether variation in people’s reasons for nondrinking explains the increased mortality. Our data come from the 1988–2006 National Health Interview Survey Linked Mortality File (N = 41,076 individuals age 21 and above, of whom 10,421 died over the follow-up period). The results indicate that nondrinkers include several different groups that have unique mortality risks. Among abstainers and light drinkers the risk of mortality is the same as light drinkers for a subgroup who report that they do not drink because of their family upbringing, and moral/religious reasons. In contrast, the risk of mortality is higher than light drinkers for former drinkers who cite health problems or who report problematic drinking behaviors. Our findings address a notable gap in the literature and may inform social policies to reduce or prevent alcohol abuse, increase health, and lengthen life.     

Stable growth in native‐dependent multistate population dynamics

Users of multistate life tables and projections have recognized that the Markovian assumptions underlying such models are unduly restrictive and should be relaxed whenever data permit. Efforts to include the influences of previous occupancies have included the incorporation of place‐of‐birth dependence. This paper addresses the stable growth properties of such generalized multistate models. It shows how place‐of‐birth‐specific stable growth measures can be calculated without projection simply by solving the characteristic equation. An example using Canadian data illustrates the argument.