Optimal Price and Quantity of Refurbished Products

Many retail product returns can be refurbished and resold, typically at a reduced price. The price set for the refurbished products affects the demands for both new and refurbished products, while the refurbishment and resale activities incur costs. To maximize profit, a manufacturer in a competitive market must carefully choose the proportion of returned products to refurbish and their sale price. We model the sale, return, refurbishment, and resale processes in an open queueing network and formulate a mathematical program to find the optimal price and proportion to refurbish. Examination of the optimality conditions reveals the different situations in which it is optimal to refurbish none, some, or all of the returned products. Refurbishing operations may increase profit or may be required to relieve a manufacturing capacity bottleneck. A numerical study identifies characteristics of the new product market and refurbished products that encourage refurbishing and some situations in which small changes in the refurbishing cost and quality provoke large changes in the optimal policy.     

The wireless network jamming problem

In adversarial environments, disabling the communication capabilities of the enemy is a high priority. We introduce the problem of determining the optimal number and locations for a set of jamming devices in order to neutralize a wireless communication network. This problem is known as the wireless network jamming problem. We develop several mathematical programming formulations based on covering the communication nodes and limiting the connectivity index of the nodes. Two case studies are presented comparing the formulations with the addition of various percentile constraints. Finally, directions of further research are addressed.     

Three explanations of marital status differences in suicide rates: social integration, marital status integration, and the culture of suicide

Our first goal is to link empirical measures of three theoretical explanations of marital status differences to the variation in male and female standardized suicide difference coefficients SSDCs in 12 developed countries, circa 1960. We include predictors of Durkheim's social integration hypothesis, Gibbs and Martin's concept of marital status integration, and norms on suicide acceptability. All three are significantly related to variation in male and female SSDCs. The second goal is to examine how our empirical indicators impact age-specific differences in the male minus female SSDC--differences that vary by age in all 12 of our study populations. The strongest predictor of these differences is the male minus female difference in the percent married.     

Spirituality and the care of patients at the end-of-life: an essential component of care

Spirituality is an essential component of the care of patients with serious illness and those that are dying. Dame Cicely Saunders developed the hospice movement based on the biopsychosocialspiritual model of care, in which all four dimensions are important in the care of patients. Of all the models of care, hospice and palliative care recognize the importance of spiritual issues in the care of patients and their families. The National Consensus Project Guidelines for Quality Palliative Care, in the United States, provides specific recommendations about all domains of care including the spiritual domain, which is recognized as a critical component of care (The National Consensus Project for Quality Palliative Care www.nationalconsensusproject.org). Studies indicate that the majority of patients would like their spiritual issues addressed, yet find that their spiritual needs are not being met by the current system of care. Interestingly, spirituality is the one dimension that seems to get slightly less emphasis than the biopsychosocial dimensions of care. Some reasons may include the difficulty with definitions of spirituality for clinical and research purposes, the time constraints and financial burdens in the current healthcare system in the United States, and the lack of uniform training for all healthcare professionals. Yet, there are theoretical and ethical frameworks that support spiritual care as well as some educational models in spirituality and health that have been successful in medical education in the United States. Spirituality can be seen as the essential part of the humanity of all people. It is at its root, relational and thus forms the basis of the altruistic care healthcare professionals are committed to. Spirituality has to do with respecting the inherent value and dignity of all persons, regardless of their health status. It is the part of humans that seeks healing, particularly in the midst of suffering. Spiritual care models are based on an intrinsic aspect that calls for compassionate presence to patients as well as an extrinsic component where healthcare professionals address spiritual issues with patients and their loved ones. Currently in the healthcare system, evidence-base models are the criteria for practice recommendations. Yet, spirituality may not be amenable entirely to strict evidence-base criteria. As hospice and palliative care continues to develop as a field, healthcare professionals are challenged to think of ways to advocate for and include the spiritual dimension of care.     

Idiocentrism, allocentrism, psychological well being and suicidal ideation: a cross cultural study

The present study examined the relationship between idiocentrism, allocentrism, psychological well being (self-esteem, depression, and social support), and suicidal ideation among 283 American college students and 343 Chinese college students. Idiocentrism was correlated with high self-esteem, high depression, and low social support, but the relationships were more likely to be significant for women than for men in both cultures. Allocentrism was primarily related to social support. As predicted, high levels of suicidal ideation were correlated with more idiocentrism, but only for women. Allocentrism was related to lower levels of suicidal ideation in both cultures, but the relationship was small. As suicide prevention may start from suicidal ideation treatment, the treatment of suicidal ideation may have to take into account cultural and personal characteristics, such as idiocentrism.     

An interactive three-stage model for mutual funds portfolio selection

The aim of this work is to be a useful instrument for helping finance practitioners on the selection of suitable mutual fund portfolios. The portfolio selection problem is characterized by imprecision and/or vagueness inherent in the required data and more generally, in the context where investors have to make decisions. In order to mitigate these problems, a three stage model has been proposed based on a multi-index model and considering several market scenarios described in an imprecise way by an expert. The proposed fuzzy model allows the Decision Maker to select, by means of an outranking method, a suitable portfolio taking into account the uncertainty related to the market scenarios and the imprecision and/or vagueness associated with the model data.     

Complexity and Adaptivity in Supply Networks: Building Supply Network Theory Using a Complex Adaptive Systems Perspective*

Supply networks are composed of large numbers of firms from multiple interrelated industries. Such networks are subject to shifting strategies and objectives within a dynamic environment. In recent years, when faced with a dynamic environment, several disciplines have adopted the Complex Adaptive System (CAS) perspective to gain insights into important issues within their domains of study. Research investigations in the field of supply networks have also begun examining the merits of complexity theory and the CAS perspective. In this article, we bring the applicability of complexity theory and CAS into sharper focus, highlighting its potential for integrating existing supply chain management (SCM) research into a structured body of knowledge while also providing a framework for generating, validating, and refining new theories relevant to real‐world supply networks. We suggest several potential research questions to emphasize how a CAS perspective can help in enriching the SCM discipline. We propose that the SCM research community adopt such a dynamic and systems‐level orientation that brings to the fore the adaptivity of firms and the complexity of their interrelations that are often inherent in supply networks.     

Focusing on Customer Time in Field Service: A Normative Approach

Although customer convenience should be rightfully considered a central element in field services, the customer experience suggests that service enterprises rarely take the customer's preferred time into account in making operational and scheduling decisions. In this paper we present the results of our exploratory research into two interrelated topics: the explicit inclusion of customer time in nonemergency field service delivery decisions and the analysis of trade‐off between the customer's convenience and field service provider's cost. Based on prior research in service quality we identify and illustrate two time‐based performance metrics that are particularly appropriate for assessing service quality in nonemergency field services: performance and conformance quality. To determine vehicle routes, we develop a hybrid heuristic derived from the existing and proven heuristic methods. A numerical example closely patterned after real‐life data is generated and used within a computational experiment to investigate alternate policies for promise time windows. Our experiment shows that over a reasonable range of customer cost parameters the policy of shorter promise time windows reduces the combined total cost incurred by the provider and the customers and should be considered a preferred policy by the field service provider. Managerial implications of this result are discussed.