Efficient Heuristics for MRP Lot Sizing with Variable Production/Purchasing Costs*

Two heuristics based on branch and bound (B&B) are developed to solve closed-loop material requirements planning (MRP) lot-sizing problems that have general product structures and variable costs. A “look ahead method'’(LAM) heuristic allows for variable production/purchasing costs and uses a single-level B&B procedure to rapidly improve lower bound values; thus, LAM efficiently uses computer-storage capacity and allows solution of larger problems. The “total average modification'’(TAM) heuristic uses B&B, applied level by level, and modified setup and carrying costs to solve the variable production/purchasing costs MRP lot-sizing problem. LAM and TAM are tested on problems and compared to heuristics in the literature. TAM may be used to solve large MRP lot-sizing problems encountered in practice.     

Efficiency Wages,Productivity and Simultaneity: A Meta-Regression Analysis

This study reports a meta-analysis of 75 estimates of the efficiency-wage effect. It reveals a strong efficiency-wage effect that depends upon whether researchers control for potential simultaneity between wages and productivity. Studies that control for simultaneity tend to report stronger effects. Clear evidence of publication selection is also found. E24, J30.

Group betweenness and co-betweenness: Inter-related notions of coalition centrality

Vertex betweenness centrality is a metric that seeks to quantify a sense of the importance of a vertex in a network in terms of its ‘control’ on the flow of information along geodesic paths throughout the network. Two natural ways to extend vertex betweenness centrality to sets of vertices are (i) in terms of geodesic paths that pass through at least one of the vertices in the set, and (ii) in terms of geodesic paths that pass through all vertices in the set. The former was introduced by Everett and Borgatti [Everett, M., Borgatti, S., 1999. The centrality of groups and classes. Journal of Mathematical Sociology 23 (3), 181–201], and called group betweenness centrality. The latter, which we call co-betweenness centrality here, has not been considered formally in the literature until now, to the best of our knowledge. In this paper, we show that these two notions of centrality are in fact intimately related and, furthermore, that this relationship may be exploited to obtain deeper insight into both. In particular, we provide an expansion for group betweenness in terms of increasingly higher orders of co-betweenness, in a manner analogous to the Taylor series expansion of a mathematical function in calculus. We then demonstrate the utility of this expansion by using it to construct analytic lower and upper bounds for group betweenness that involve only simple combinations of (i) the betweenness of individual vertices in the group, and (ii) the co-betweenness of pairs of these vertices. Accordingly, we argue that the latter quantity, i.e., pairwise co-betweenness, is itself a fundamental quantity of some independent interest, and we present a computationally efficient algorithm for its calculation, which extends the algorithm of Brandes [Brandes, U., 2001. A faster algorithm for betweenness centrality. Journal of Mathematical Sociology 25, 163] in a natural manner. Applications are provided throughout, using a handful of different communication networks, which serve to illustrate the way in which our mathematical contributions allow for insight to be gained into the interaction of network structure, coalitions, and information flow in social networks.     

Overcoming Barriers to Using Empirically Supported Therapies to Treat Childhood Anxiety Disorders in Social Work Practice

Anxiety disorders are among the most common psychiatric disorders in children and adolescents. Most empirically supported treatments (ESTs) for pediatric anxiety disorders include various cognitive-behavioral methods. Although demonstrated efficacious in controlled and clinic settings, there are barriers to implementing these types of therapies in social work settings due to beliefs about the usefulness of ESTs in community settings; limitations of treatment manuals; time constraints of implementing ESTs; fidelity and flexibility of implementing ESTs; and limited training opportunities. This article provides an overview of ESTs for childhood anxiety disorders, highlighting options for overcoming common barriers to implementing ESTs. Collaborative multi-method approaches to advance implementation of ESTs in social work practice are suggested.     

New cultural economies of marginality: revisiting the West Coast,South Island,New Zealand

Marginal regions have been the subject of political concern and remedial action in western states for several decades now. The West Coast of the South Island of New Zealand is an interesting case study in this regard, for recent economic growth has confounded earlier expectations of post-restructuring decline, while also contradicting several of the nostrums of new regionalism. In an effort to understand this trajectory, this paper draws on documents from public and private sector organisations, newspaper articles and field visits to examine developments in four key sectors of the West Coast's economy: mining, dairy farming, forestry and tourism. Economic growth is found to be closely linked to the cultivation of new markets for primary products, but efforts to rework the cultural dimensions of marginality have also been important. Value has been added to specific products through the insertion of references to the region's alpine and forested landscapes. Isolation and peripherality have been recast in more positive terms, echoing the broader reframing of New Zealand as a scenic, unspoiled destination. In adopting a cultural economic perspective on marginal regions, the paper illustrates the significance of symbolic forms of value, the potentially flexible nature of marginality as a discursive category, and the importance of the networks which connect regions to national and international flows of capital and tourists.     

Racialization in a ‘homogenous’ society? The case of Buraku people in Japan

This paper examines the puzzling status of Buraku people in Japan through the methodological prism of historical sociology. I develop a theoretical approach that emphasizes the concept of racialization to illuminate the historical and social construction of Buraku status. I propose this approach as a complementary alternative to prior analytic perspectives. Two major perspectives have dominated research on the status of Buraku people. First, an earlier approach that focused on the legacy of caste discrimination. The second framework focuses on Buraku people as part of the struggle for universal human rights. This article raises three basic, but interrelated questions about the historical development of Buraku status in Japan. Why did the Buraku people become subject to such overt discrimination in local community life, and through government policy? How was the state involved in the social construction of Buraku people? How did the Buraku liberation struggles challenge formalized discrimination?     

A further examination of antecedents of correctional staff life satisfaction

Working in corrections is not only a demanding job, but a socially important one. While a growing number of studies have examined how the work environment impacts the job stress, job satisfaction, and organizational commitment of staff, very few studies have examined how working in corrections impacts the life satisfaction of workers. The current study utilized OLS regression to examine the antecedents of life satisfaction among staff at a Midwestern private prison. Job satisfaction had a positive relationship with life satisfaction, while age, work on family conflict, family on work conflict, and job involvement all had statistically significant negative effects. Finally, perceptions of the level of financial rewards, job stress, organizational commitment, gender, race, educational level, tenure, supervisory status, position, marital status, and having children, all had non-significant associations with overall satisfaction with life.     

Class,race, and the disposal of urban waste: Locations of landfills,incinerators, and sewage treatment plants

This study compared the socioeconomic status, racial composition, and ethnic composition of 49 randomly selected U.S. cities with those of the census tracts containing the solid waste disposal facilities and sewage treatment plants for those cities. Contrary to the environmental racism and classism hypotheses, residents of tracts with landfills or incinerators had higher incomes and were less likely to be minority group members than residents of the cities that generated the refuse—although they did have somewhat lower education levels. There were few differences between the population characteristics of the cities and the census tracts that contained their sewage treatment plants. Possible explanations for these findings are discussed.