Common characterizations of the untrapped set and the top cycle

We give some characterizations for both the untrapped set and the top cycle choice functions. We link these characterizations with the well-known characterization of the maximal elements choice function. Our characterizations strongly rely on the notion of “two-tier domination”.     

Free energy methods for Bayesian inference: efficient exploration of univariate Gaussian mixture posteriors

Because of their multimodality, mixture posterior distributions are difficult to sample with standard Markov chain Monte Carlo (MCMC) methods. We propose a strategy to enhance the sampling of MCMC in this context, using a biasing procedure which originates from computational Statistical Physics. The principle is first to choose a “reaction coordinate”, that is, a “direction” in which the target distribution is multimodal. In a second step, the marginal log-density of the reaction coordinate with respect to the posterior distribution is estimated; minus this quantity is called “free energy” in the computational Statistical Physics literature. To this end, we use adaptive biasing Markov chain algorithms which adapt their targeted invariant distribution on the fly, in order to overcome sampling barriers along the chosen reaction coordinate. Finally, we perform an importance sampling step in order to remove the bias and recover the true posterior. The efficiency factor of the importance sampling step can easily be estimated a priori once the bias is known, and appears to be rather large for the test cases we considered.     

Social Embodiment of Technical Devices: Eyeglasses Over the Centuries and According to their Uses

This article is an attempt to prepare the ground for the analysis and theorization of the connection between the body and technical devices emerging from miniaturized wearable technologies. The research object is a secular and common “body object,” namely, eyeglasses. The article reviews the social history of this artifact and analyzes its patterns of use, showing how the distributed sociotechnical networks of action containing these simple optical systems are constantly deconfigured and reconfigured. In other words, the device is not simply subject to physical incorporation. The unstable balance between the artifact's projection onto the surrounding space and its attachment to the physical body is analyzed through the heterogeneousness of bodies coming into play as the device is socially embodied. As the corporal frame and physical, distributed, and social bodies overlap, the notion of “bodies object” emerges. This covers the artifact-related and social environment, the plural nature of which could be of great value to research and development teams, helping them to diversify their representations of the user, as an agent acting in a variety of networks with a variety of bodies.     

The segregative properties of endogenous formation of jurisdictions with a welfarist central government

This paper examines the segregative properties of Tiebout-type process of jurisdiction formation by freely mobile households in the presence of a central government which makes equalization transfers across jurisdictions so as to maximize a generalized utilitarian or a max–min objective. It is shown that the introduction of such a central government significantly affects the set of stable jurisdiction structures. It is also shown that the class of households additively separable preferences that guarantees the wealth segregation of any stable jurisdiction structure is unaffected by the presence of a central government if this government uses a generalized utilitarian objective.     

Intergenerational reliance on social assistance: Evidence from Canada

This paper provides the first analysis of the intergenerational transmission of participation in a Canadian social assistance program. Two sources of intergenerational transmission are taken into account: one that is due to a possible causal link between parents' and children's participation, and one that is due to a correlation between individual and environment specific characteristics across generations. The basic data come from the Québec government's administrative records and cover 17,203 young people who were 18 years old in 1990 and whose parents were recipients of social assistance during at least one month between 1979 and 1990. The results reveal that, on average, a one-percentage unit increase in parental participation during the youth's pre-adult years (age 7–17) raises the youth's participation rate by 0.29 percentage unit during early adulthood (age 18–21). This impact is stronger during the early stages of childhood (age 7–9) and during late adolescence (age 16–17).     

Eliciting vague but proper maximal entropy priors in Bayesian experiments

Priors elicited according to maximal entropy rules have been used for years in objective and subjective Bayesian analysis. However, when the prior knowledge remains fuzzy or dubious, they often suffer from impropriety which can make them uncomfortable to use. In this article we suggest the formal elicitation of an encompassing family for the standard maximal entropy (ME) priors and the maximal data information (MDI) priors, which can lead to obtain proper families. An interpretation is given in the objective framework of channel coding. In a subjective framework, the performance of the method is shown in a reliability context when flat but proper priors are elicited for the Weibull lifetime distributions. Such priors appear as practical tools for sensitivity studies.     

L'intensification du travail en débat. Ethnographie et histoire aux chaînes de Peugeot-Sochaux

With the use of ethnography and history, this study of work in the Peugeot-Sochaux automobile factory in the last half of the 20th century makes us stand back from a unifying, generalized view of the intensification of labor. For one thing, variations in work rules and the diversity of related problems bring to light the tensions underlying the issue of workloads. For another, detecting when workloads are actually heavier and more stressful calls for taking into account a variety of periods and tendencies while studying working conditions. This study conducted in workshops in the Sochaux plant leads us away from a quantitative, abstract view of the intensification of work. We are thus led to examine the concrete changes that affect employment conditions and the technical aspects of work over a longer term. Far from losing sense, the idea of an intensification of work processes becomes richer and more relevant for analyzing the world of work.     

Valuation effects of corporate strategic transactions in the cleantech industry

This paper investigates capital market reactions to announcements of corporate strategic transactions in the clean technology, or cleantech, industry. Using the event study method in a multi-country setting, we exploit a dataset of 328 hand-collected announcements of mergers and acquisitions, joint ventures, and asset disposals that took place between 2001 and 2011. We provide strong evidence of significant wealth gains from cleantech deals. On average, cleantech companies earn significantly higher abnormal returns than non-cleantech companies, confirming the beneficial idiosyncrasies of the cleantech industry. These high premia are likely driven by government interventions that are believed to be a necessary pre-condition for development of clean technology. Alternatively, the premia are commanded by the acquisition of cutting-edge environmental innovations and the positive credibility spillover inherent in cleantech deals.     

Still more on the Tournament Equilibrium Set

Schwartz (Soc Choice Welfare 3:271–291, 1990) proposed a solution concept (the Tournament Equilibrium Set) for choosing from a tournament and stated some conjectures about this solution. Laffond et al. (Math Sci Hum 123:37–44, 1993) introduced further conjectures and showed the links between some of them. In this short note, we show that one of the conjectures stated by Schwartz (1990) is false. We also complete a result given in Laffond et al. (1993). I gratefully thank J.-F. Laslier for his remarks and for introducing me to this topic.     

A global risk assessment model for civil wars

In this study, we construct a multivariate model that assesses the risk of an outbreak of civil war in a country over a period of 5 years into the future. In addition to structural factors of state weakness, which have dominated the literature on civil war onset, this model includes repression of basic human rights to personal integrity – an important harbinger of wars to come – as an aspect of state behavior. Our aim is not to explore the causal factors of civil war onset, but to build a model that includes indicators that correlate with civil war outbreak and may be used to predict it. Based on two versions of the model – logit and neural network – out-of-sample risk assessments for three different time periods are generated and compared to the historical record of civil war outbreak during those years. In addition, the model’s ability to produce in-sample risk assessments over a 5-year period is tested. Finally, we compute truly predictive civil war risk assessments for all countries for which data are available, for the years 2008–2012. The analyses show that with a relatively simple model and based on publicly available data sources, meaningful civil war risk assessments can be computed. The quality of the predictions exceeds that of prominent studies, in which the risk of interstate war is assessed.