Besoins individuels et collectifs: Nanacatlan,Mexico

The author intends both to describe a native credit institution in a peasant community and to analyse its overt and covert functions. The community fund, managed by the local authority (presidencia auxiliar) is theoretically available to all household heads who can show solvency (e.g., by pawning a piece of property, usually land). Apart from assisting peasants who face a shortage of cash, another overt function of the system is to finance, with the interests which are paid back on the loans, the functioning of the local administration. Because of the great economic discrepancies between peasants (50 per cent of them own no land, while 2.5 per cent own 30 per cent of the land) one real, although covert, function of the credit institution is to channel a substantial amount of cash to the local upper class (which has little access to banking facilities). Therefore it actually enhances their economic domination over the majority of villagers, which fact allows us to understand the strict control they have exerted over the management of the fund since its foundation, some 40 years ago.     

Epidemiologic network inference

Statistics and Computing - In many epidemiologic models, a disease is assumed to spread along a contact network. We aim to infer this network, in addition to the epidemiologic model parameters,...     

Child welfare workers' practice in cases involving domestic violence

This paper reports the findings of an exploratory and qualitative study of child welfare workers' practice in cases involving domestic violence. The research aimed to focus on child welfare workers' interventions with families experiencing domestic violence, elements influencing the child welfare workers' decisions, and the factors facilitating and creating obstacles for intervention. An analysis of the qualitative data showed that child welfare workers have different ways of intervening in cases involving domestic violence. Also, the interventions were especially centred on women victims of violence and they were held responsible for protecting their children. Finally, the dilemmas and difficulties which child welfare workers face in these cases are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Education,Mobility and Employers’ Monopsony Power: A Search‐theoretic Analysis

Abstract. We analyse the efficiency of schooling choices in a wage‐posting search equilibrium model with on‐the‐job search. The workers have multidimensional skills and the search market is segmented by technology. Education determines the scope — or adaptability— of individual skills. Individuals obtain schooling to leave unemployment more quickly and to climb the wage ladder rapidly through job‐to‐job mobility — that is, to speed up job shopping. Education reduces firms’ monopsony power in the wage determination by improving workers’ mobility. As a result, the wage distribution shifts rightward with aggregate schooling. However, the ratio of vacant jobs to job seekers also falls in each sector. Either one or the other externality may dominate, implying, respectively, under‐ or over‐education. A combination of minimum wage and schooling fee can decentralize the efficient allocation.     

The min-up/min-down unit commitment polytope

The min-up/min-down unit commitment problem (MUCP) is to find a minimum-cost production plan on a discrete time horizon for a set of fossil-fuel units for electricity production. At each time period, the total production has to meet a forecast demand. Each unit must satisfy minimum up-time and down-time constraints besides featuring production and start-up costs. A full polyhedral characterization of the MUCP with only one production unit is provided by Rajan and Takriti (Minimum up/down polytopes of the unit commitment problem with start-up costs. IBM Research Report, 2005). In this article, we analyze polyhedral aspects of the MUCP with n production units. We first translate the classical extended cover inequalities of the knapsack polytope to obtain the so-called up-set inequalities for the MUCP polytope. We introduce the interval up-set inequalities as a new class of valid inequalities, which generalizes both up-set inequalities and minimum up-time inequalities. We provide a characterization of the cases when interval up-set inequalities are valid and not dominated by other inequalities. We devise an efficient Branch and Cut algorithm, using up-set and interval up-set inequalities.     

Wage Bargaining with On‐the‐Job Search: Theory and Evidence

Most applications of Nash bargaining over wages ignore between‐employer competition for labor services and attribute all of the workers' rent to their bargaining power. In this paper, we write and estimate an equilibrium model with strategic wage bargaining and on‐the‐job search and use it to take another look at the determinants of wages in France. There are three essential determinants of wages in our model: productivity, competition between employers resulting from on‐the‐job search, and the workers' bargaining power. We find that between‐firm competition matters a lot in the determination of wages, because it is quantitatively more important than wage bargaining à la Nash in raising wages above the workers' “reservation wages,” defined as out‐of‐work income. In particular, we detect no significant bargaining power for intermediate‐ and low‐skilled workers, and a modestly positive bargaining power for high‐skilled workers.     

Constraint-based model for the cyclic multi-hoists scheduling problem

This article presents a method for the resolution of a material handling scheduling problem. The case studied is a real industrial problem. It consists of finding a cyclic schedule for hoist movements in a treatment surface shop. In this kind of facility, several hoists are used for all the handling operations and they have to share common zones. Then it is necessary to control that there is no collision. The mathematical formulation of the problem is based on a combination of disjunctive constraints. The constraints describe either movement schedule or collision avoidance. The resolution procedure presented identifies all the collision configurations and then uses a branch and bound-like algorithm to find the optimal solution of a given problem. The language chosen for our implementation is the constraint logic programming language: Prolog IV, which is able to solve constraints with rational variables. It actively uses the constraint propagation mechanism that can be found in several languages.     

Evaluation of a Sexual Abuse Prevention Workshop in a Multicultural,Impoverished Urban Area

Participants in the ESPACE sexual abuse prevention workshop were in grades 1 through 4 and attended three Montreal, Canada, public schools in low socioeconomic areas. The sample was culturally diverse, with half born outside of Canada. An evaluation was conducted to explore the effects associated with participating in the workshop and the effects of booster sessions conducted two years later. Outcomes included knowledge gained, the ability to offer behavioral responses to abusive situations, peer victimization, sense of safety, empathy, self-efficacy, and support. Results revealed that participants in this sample obtained low scores on measures of sexual abuse knowledge and that short booster sessions that elicit children's recall of the learned material might produce greater improvements.     

Interweaving Objects,Gestures, and Talk in Context

In a large French hospital, a group of professional experts (including physicians and software engineers) are working on the computerization of a blood-transfusion traceability device. By focusing on a particular moment in this slow process of design, we analyze their collaborative practices during a work session. The analysis takes a praxeological and interactionist approach and is inspired by discussions on the role of artifacts in social practices currently developed within various research frameworks in this field: activity theory, distributed cognition, conversation analysis, and actor network theory. After a brief presentation of the place of objects and artifacts in these ways of approaching action and human cognition, we show how the collective activity analyzed here is generated by the interweaving of discursive, gestural, and artifactual resources.