Employment protection legislation and job stability: A European cross‐country analysis

Based on Eurostat data on wage employment for the period 1999–2006, this article investigates the dynamics of job tenure across the European Union. The authors’ analysis shows no generalized decline in job tenure, but a trend towards shorter tenure among young workers (aged 15–24 years) in many European countries. Their regression results indicate that this trend is associated with the weakening of employment protection provided by law and by trade unions. Given young workers’ weak individual bargaining power, the trend towards individualization of the employment relationship may thus affect them disproportionately.     

Using heuristics to find minimal unsatisfiable subformulas in satisfiability problems

In this paper, we propose efficient algorithms to extract minimal unsatisfiable subsets of clauses or variables in unsatisfiable propositional formulas. Such subsets yield unsatisfiable propositional subformulas that become satisfiable when any of their clauses or variables is removed. These subformulas have numerous applications, including proving unsatisfiability and post-infeasibility analysis. The algorithms we propose are based on heuristics, and thus, can be applied to large instances. Furthermore, we show that, in some cases, the minimality of the subformulas can be proven with these algorithms. We also present an original algorithm to find minimum cardinality unsatisfiable subformulas in smaller instances. Finally, we report computational experiments on unsatisfiable instances from various sources, that demonstrate the effectiveness of our algorithms.     

Transport policy and public involvement

This paper examines the possibility of establishing a public space of deliberation concerning transport policy. It deals with the question of whether it is possible to envisage instances of concertation that deflect conflict. Based mostly on French experience with public inquiries on transport infrastructure, it discusses the relevance and applicability of the sociology of collective action, as well as theories of deliberative democracy. The paper's main argument is that concertation does not occur in a vacuum but is instead structured by power relations. It is, therefore, first and foremost an opportunity to express dissatisfaction and frustration. At the same time, public debate represents—perhaps for the same reason—an opportunity to criticize forms of social domination. It thus may give rise to citizen mobilization rather than help contain it, as is often naively expected by its promoters within the public policy administration. Conflict is thus always the actual subject of public debate.     

Formation et calcul des prix : le travail de tarification dans la grande distribution

Sociologists have recently been rasing questions about how prices are set in various markets. Although their seminal studies have explained the many processes and variables that come into play, they do not enable us to describe the concrete procedures whereby prices are actually calculated. This empirical case study explores the sophisticated methods of calculating the prices of products distributed in a French retail hypermarket chain. Three major conclusions are drawn. First of all, the law enters into the delimitation of the “space” for calculating the prices that distributors set for selling to consumers. Secondly, the choice of a procedure for performing the calculation affects the balance of power between marketing professionals in the struggle to control their shares in the value. Thirdly, the “consumer sale price” does not result directly either from the relation between supply and demand or from micronegotiations between suppliers and distributors. Instead, it tends to ensue from the linkage between several, heterogenous “spaces” of calculation. This study describes the actors, tools and know-how involved in defining these spaces.     

Relative Contributions of Treatment-Related Changes in Communication Skills and Dyadic Coping Skills to the Longitudinal Course of Marriage in the Framework of Marital Distress Prevention

Most prior studies of skill-based preventive interventions for couples compare changes in problem-solving behaviors made by treated couples with those made by control couples. Unexpected findings in these studies highlight the need to examine within-group variability in behavior change among treated couples, alternative behavioral domains, including dyadic support and coping, and partners' intended and actual use of strategies taught in the interventions. A 24-month longitudinal study of 109 couples participating in an 18-hour intervention designed to enhance communication and dyadic coping revealed that marital outcomes are enhanced to the extent that (a) wives increase their positive problem-solving behavior and husbands decrease their negative problem-solving behavior over the course of the intervention, and (b) wives and husbands increase their positive dyadic coping behaviors, and husbands decrease their negative dyadic coping behaviors. Moreover, greater postintervention use of strategies taught in the intervention program produced better outcomes, and wives' improvements in positive and negative dyadic coping strengthened associations between strategy use and relationship satisfaction. Discussion emphasizes the importance of devising interventions that target key interpersonal processes and that motivate participants to display newly acquired behaviors.     

Equilibrium,affinity, dissociation constants,IC5O: Facts and fantasies

The interaction between ligands and receptors is often described in terms of 50% inhibitory concentrations (IC50). However, IC50 values do not accurately reflect the dissociation constants (Kd), and the domain of application and precision of proposed approximations for Kd estimation are unclear. The effect of affinity and of experimental conditions on the differences between IC50 and Kd has been assessed from exact mass action law calculations and from computer simulations. Competitions between [¹¹¹In]DTPA‐indium and a few metal‐DTPA complexes for binding to a specific antibody are discussed as a practical example. Exact calculations of competition assays have been implemented in Microsoft Excel and performed for a variety of concentrations of receptor, tracer, and competitor. The results are identical to those of software packages. IC50 is found larger than Kd by less than 20% only when tracer concentration is small compared with Kd and to the receptor concentration and when this receptor concentration is small compared with Kd. Otherwise, Kd and IC50 may be very different and approximations proposed in the literature to obtain Kd values from graphically derived IC50 are not acceptable as soon as the concentrations of tracer or of receptor approach Kd. Under most experimental conditions, IC50 values do not reflect Kd values. Using available software packages to determine and report Kd values would allow for more meaningful comparisons of results obtained under different experimental conditions.     

Alien plant species do have a clear preference for different land uses within urban environments

Since neophytes can become invasive in the future, untangling their ecological preferences is of paramount importance, especially in urban areas where they represent a substantial proportion of the local flora. Studies exploring alien species assemblages in urban environments are however scarce. This study aims to unravel alien plant species preferences for five urban land uses (densely built-up areas, open built-up areas, industrial areas, broadleaved urban forests, and agricultural areas and small landscape elements). We took the city of Brussels as a model, in which we recorded all vascular species growing spontaneously in grid cells of 1 km². We tested two different ways of classifying the 1-km² cells: (1) We simply associated each cell with its dominant land cover; (2) We used a fuzzy approach for which the degree of association of a given cell to a given land cover depended on the proportion of that land cover within the cell. For both classification methods, we calculated the indicator species of the resulting land cover types based on alien species only. The crisp and fuzzy classifications identified 33 and 49 species, respectively, with a clear preference for some urban land use types (from a total of 129 alien plant species analyzed). Results showed that urban land use types having apparently similar environmental conditions can actually harbor different neophyte assemblages. Fine-tuning the categorization of urban environments in future ecological studies is therefore important for understanding spatial patterns of alien species occurrence.     

The Theory of Conditionality: An Illustration of the Place of Norms in the Field of Social Thinking

In the field of the central core theory of social representations, research which has focused on the normative aspects is relatively recent as it dates back little more than ten years. The theory of conditionality which developed from research into the periphery of representation results from this. It is a particularly fruitful theory to explain “normative latitudes” and the behaviour accruing to them. One of the particularities of these works stresses the importance of linking the normative aspects with specific methods and/or analyses. In this paper, we will illustrate it via a specific tool developed in the field of traffic psychology: the Conditional Script Questionnaire (CSQ). This approach makes it possible to highlight the interactions between two systems of norms: the legal system and the social system. The implication of norms is fundamental in different processes already studied such as social influence or identity processes, and this article can be considered as an illustration of the place of norms in the field of social thinking.