Supply Chain Scheduling: Distribution Systems

We study conflict and cooperation issues arising in a supply chain where a manufacturer makes products which are shipped to customers by a distributor. The manufacturer and the distributor each has an ideal schedule, determined by cost and capacity considerations. However, these two schedules are in general not well coordinated, which leads to poor overall performance. In this context, we study two practical problems. In both problems, the manufacturer focuses on minimizing unproductive time. The distributor minimizes customer cost measures in the first problem and minimizes inventory holding cost in the second problem. We first evaluate each party's conflict, which is the relative increase in cost that results from using the other party's optimal schedule. Since this conflict is often significant, we consider several practical scenarios about the level of cooperation between the manufacturer and the distributor. These scenarios define various scheduling problems for the manufacturer, the distributor, and the overall system. For each of these scheduling problems, we provide an algorithm. We demonstrate that the cost saving provided by cooperation between the decision makers is usually significant. Finally, we discuss the implications of our work for how manufacturers and distributors negotiate, coordinate, and implement their supply chain schedules in practice.     

Status Roles and Recall of Nonverbal Cues

In two experiments, interpersonal status was experimentally manipulated by assigning one dyad member to be the owner of a mock art gallery and the other to be the owner's assistant. Without forewarning, participants were asked immediately following the interaction to recall their partner's hand gestures, self-touch, gazing, smiling, and nodding. Accuracy of recall was determined by comparing these ratings to their partners' behavior as coded from the videotape. In both experiments, assistants were more accurate at recalling the amount of owners' self-touch than vice versa, but there was little evidence of an accuracy difference in recall of the other nonverbal cues. When accuracy was defined as the correlation between a participant's ratings of the partner's behaviors and the partner's actual behaviors, there was evidence that assistants were more accurate than owners when a combined p-value was calculated across both studies.     

Preventing depression in high-risk college women: a report of an 18-month follow-up.

The authors tested the long-term effectiveness of a cognitive-behavioral group intervention in reducing depressive symptoms, decreasing negative thinking, and enhancing self-esteem in 92 college women aged 18 to 24 years who ere at risk for clinical depression. The women were randomly assigned to either an experimental or a no-treatment control group. The experimental group participated in a 6-week cognitive-behavioral intervention that targeted identification and reduction of negative thinking, using such techniques as thought stopping and affirmations. Data on depressive symptoms, self-esteem, and negative thinking were collected before the intervention and at intervals of 1, 6, and 18 months postintervention. The women in the intervention group experienced a greater decrease in depressive symptoms and negative thinking and a greater increase in self-esteem than those in the control group. The beneficial effects continued over an 18-month follow-up period. These findings support the importance of thought stopping and affirmations as prevention interventions with at-risk college women.     

Efficiency of weighted averages

When combining estimates of a common parameter (of dimension d?1$d?1$) from independent data sets—as in stratified analyses and meta analyses—a weighted average, with weights ‘proportional’ to inverse variance matrices, is shown to have a minimal variance matrix (a standard fact when d=1$d=1$)—minimal in the sense that all convex combinations of the coordinates of the combined estimate have minimal variances. Minimum variance for the estimation of a single coordinate of the parameter can therefore be achieved by joint estimation of all coordinates using matrix weights. Moreover, if each estimate is asymptotically efficient within its own data set, then this optimally weighted average, with consistently estimated weights, is shown to be asymptotically efficient in the combined data set and avoids the need to merge the data sets and estimate the parameter in question afresh. This is so whatever additional non-common nuisance parameters may be in the models for the various data sets. A special case of this appeared in Fisher [1925. Theory of statistical estimation. Proc. Cambridge Philos. Soc. 22, 700–725.]: Optimal weights are ‘proportional’ to information matrices, and he argued that sample information should be used as weights rather than expected information, to maintain second-order efficiency of maximum likelihood. A number of special cases have appeared in the literature; we review several of them and give additional special cases, including stratified regression analysis—proportional-hazards, logistic or linear—, combination of independent ROC curves, and meta analysis. A test for homogeneity of the parameter across the data sets is also given.     

Everyday territories: homelessness,outreach work and city space

This article develops a situational approach to understanding urban public life and, in particular, the production of urban territories. Our aim is to examine the ways in which city space might be understood as comprising multiple, shifting, mobile and rhythmed territories. We argue that such territories are best understood through attending to their everyday production and negotiation, rather than handling territory as an a priori construct. We develop this argument from the particular case of the street‐level politics of homelessness and street care. The experience of street homelessness and the provision of care in the public spaces of the city is characterised by precarious territorial claims made and lost. We describe some of the ways in which care work with rough sleepers is itself precarious; ‘homeless’, in lacking a distinct setting in which it might get done. Indeed, outreach work takes place within and affirms homeless territories. The affirmation of territory is shown to be central to the relationship developed between the workers and their rough sleeping clients. We also show, however, the ways in which outreach workers operate on territory not their own, twice over. Outreach work is precarious in that it is practised within, and can run counter to, other territorial productions in which the experience of urban need and the work and politics of care are entangled. In sum, this article aims to move beyond static and binary understandings by developing a mobile and situational approach to city space which recognises the intensive yet overlooked work of territorial production.