Posner, Economics and the Law: from Law and Economics to an Economic Analysis of Law.

The purpose of this article is to discuss Posner's economic analysis of law and to analyse the differences between his economic analysis of law and law and economics. We propose and demonstrate a twofold original argument. First, we show that Posner does not only propose an economic analysis of the working of the legal system but also that his approach has changed in the early 1970s, shifting from a law and economics perspective in which the focus is put on the working of the economic system to an economic analysis of law in which the emphasis is put on the functioning of the legal system. He appears then no longer influenced by Aaron Director and Ronald Coase but rather by Gary Becker. Therefore, and this is the second part of our demonstration, we show that the evolution in Posner's works essentially derives from the influence of Becker and the adoption by the former of the methodological views of the latter. More precisely, we claim that Posner no longer retains a -- restrictive -- definition of economics by subject matter but that he aligns himself on Becker and his broader definition of economics placing nonmarket decisions and method at the core of the discipline. In other words, we argue that Posner is the first who transposes Becker’s definition of economics in law and economics and that this is precisely what makes Posner's economic analysis of law possible and specific, and also of particular importance.

Set-Aside versus Quotas in Contracts for Agro-Environmental Regulation

In this paper, we analyze the simultaneous regulation of several goods produced on agricultural land such as environmental amenities and crops. This analysis is conducted using a general two goods model where all agricultural land is used for production. The regulation authority can regulate these goods either through set aside requirements or production quotas. The paper focuses on information asymmetry about some farm performance index creating adverse selection. When public funds are non costly we show that the net social welfare induced by the two types of contracts are equal. In general we also show that if the goal of the regulation is to decrease the production of the quota good it is better to use the quota contract. On contrary if the regulation aims at increasing the production of the quota good, it is better to use a set aside contract.Political Economy,

Stabilising a nulling interferometer using optical path difference dithering

Context. Nulling interferometry has been suggested as the underlying principle for the Darwin and TPF-I exoplanet research missions. Aims. There are constraints both on the mean value of the nulling ratio, and on its stability. Instrument instability noise is most detrimental to the stability of the nulling performance. Methods. We applied a modified version of the classical dithering technique to the optical path difference in the scientific beam. Results. Using only this method, we repeatedly stabilised the dark fringe for several hours. This method alone sufficed to remove the 1/ f component of the noise in our setup for periods of 10 minutes, typically. These results indicate that performance stability may be maintained throughout the long-duration data acquisitions typical of exoplanet spectroscopy. Conclusions. We suggest that further study of possible stabilisation strategies should be an integral part of Darwin/TPF-I research and developmen

Abundance Patterns in S-type AGB stars : Setting Constraints on Nucleosynthesis and Stellar Evolution Models

During the evolution on the AGB, S-type stars are the first objects to experience s-process nucleosynthesis and third dredge-ups, and therefore to exhibit sprocess signatures in their atmospheres. Their significant mass loss rates (10^-7 to 10^-6 M*/year) make them major contributors to the AGB nucleosynthesis yields at solar metallicity. Precise abundance determinations in S stars are of the utmost importance for constraining e.g. the third dredge-up luminosity and efficiency (which has been only crudely parameterized in all current nucleosynthetic models so far). Here, dedicated S-star model atmospheres are used to determine precise abundances of key s-process elements, and to set constraints on nucleosynthesis and stellar evolution models. A special interest is paid to technetium, an element with no stable isotopes (99Tc, the only isotope produced by the s-process in AGB stars, has a half-life of 2.1 x 10^5 years). Its detection is considered as the best signature that the star effectively populates the thermally-pulsing AGB phase of evolution. The derived Tc/Zr abundances are compared, as a function of the derived [Zr/Fe] overabundances, with AGB stellar model predictions. The [Zr/Fe] overabundances are in good agreement with the model predictions, while the Tc/Zr abundances are slightly overpredicted. This discrepancy can help to set better constraints on nucleosynthesis and stellar evolution models of AGB stars.Comment: 5 pages, 3 figures, To be published in the proceedings of the conference "Why Galaxies Care about AGB Stars II", held in Vienna, August 16-20, 2010; eds Franz Kerschbaum, Thomas Lebzelter, and Bob Wing, ASP Conf. Serie

Evaluation des politiques de transports et équité spatiale

Un système de transport irrigue un espace dont tous les lieux ne jouissent pas de la même accessibilité, que cet espace soit local, national ou international. Cela pose le problème de l'inégalité face au droit au transport et plus généralement celui de l'iniquité spatiale. Dans le cas de l'évaluation des politiques de transport, la prise en compte de l'équité spatiale pose un certain nombre de problèmes. Cela renvoie à la contradiction entre efficacité et équité. L'incapacité du calcul économique, tel qu'il est usuellement pratiqué, à considérer des objectifs de redistribution est clairement liée à son principe fondé sur l'hypothèse d'une répartition optimale. Nous nous proposons dans un premier temps de formaliser cette difficulté, puis nous nous interrogeons sur la manière d'arbitrer au mieux la contradiction. Plusieurs pistes sont alors étudiées. La première consiste en l'intégration de la notion d'accessibilité dans le calcul du surplus de l'usager selon la proposition de KOENIG. Les suivantes reposent sur les propositions des économistes de la redistribution et suggèrent, en amont du problème, de s'interroger sur la définition de l'équité spatiale. Une méthode est proposée qui intègre à l'évaluation standard une dimension redistributive.calcul économique ; équité spatiale ; redistribution ; accessibilité ; utilitarisme ; évaluation redistributive