Parity violation and the mean field approximation for the anyon gas

We examine an approach to justifying the mean field approximation for the anyon gas, using the scattering of anyons. Parity violation permits a nonzero average scattering angle, from which one can extract a mean radius of curvature for anyons. If this is larger than the interparticle separation, one expects that the graininess of the statistical magnetic field is unimportant, and that the mean field approximation is good. We argue that a non-conventional interaction between anyons is crucial, in which case the criterion for validity of the approximation is identical to the one deduced using a self-consistency argument.Comment: 11 pages, UdeM-LPN-TH-13

The Alter-EU Movement and European Governance

The recent obstacles to European integration have relaunched a debate that makes ethics and transparency core parts of the European agenda. This hints at the possibility of a more demanding regulation of lobbyists and, in broader terms, of all parties involved in the European Governance. The dynamics currently at work testify to growing receptiveness of EU officials to the claims of the Alter-EU movement; to the power struggles between representation models; and to the existence of more or less open, virtuous and/or citizen-controlled conceptions of public action that reflect differentiated national traditions and practices (...)

Projet d'appui au secteur élevage. Programme de développement des animaux villageois au Burkina Faso (rapport provisoire). Mission d'évaluation

Le projet de développement de l'aviculture villageoise, demarré en 1978, est devenu en 1989 le projet de développement des animaux villageois (PDAV). Il a pour objectif le développement des volailles, des petits ruminants et des porcs sur l'ensemble du territoire du Burkina Faso. Ses activités portaient, fin 1992, sur 15 provinces du pays et ont été étendues à 12 autres en 1993. L'action du PDAV s'est traduite par l'émergence d'une véritable filière commerciale adaptée au marché intérieur et à l'exportation des volailles villageoises. Les activités principales sont la formation et l'encadrement de vulgarisateurs volontaires villageois et l'approvisionnement de ces derniers en intrants, essentiellement en vaccin contre la maladie de Newcastle et en antiparasitaires. Ce rapport dresse un bilan technique et économique du PDAV. Actuellement, les pouvoirs publics souhaitent étendre l'activité du PDAV en secteur villageois, sur l'ensemble du pays, aux petits ruminants et aux porcs. Il est proposé, dès fin 1995, de constituer une structure d'approvisionnement de type priv

Duration of Poverty Spells in Europe. EPAG Working Paper 47, 2003

The increasing number of waves available form the European Community Household Panel (ECHP) now makes comparative research of poverty dynamics in EU countries possible. In this paper, we use the first five waves of ECHP to examine the structure of spells, their average duration and the determinants of duration. We do so using ordered logit and hazard rate models. The paper seeks to evaluate how well the different welfare states of Europe perform in terms of preventing recurrent and persistent income poverty and what household and individual characteristics influence poverty duration. Because we use cross-national data on longitudinal poverty we are able to increase our understanding of the effect of the institutional context within which poverty occurs. We show that the country welfare regimes strongly influence long run poverty. In particular, countries in the social democratic tradition are found to do a better job of preventing poverty and long-term poverty. Countries in the liberal tradition and southern European countries display much higher rates of poverty and longer durations of poverty spells. Surprisingly, however, the Netherlands is found not to stand up to its social democratic image in term of exits from poverty: exits rates from poverty are low compared to other EU countries. We provide evidence on the efficiency of labour market mechanisms in terms reducing the risk of long-term poverty, and on the effect of the (changing) household context on the poverty risk. Jobless households are not only more likely to become persistently poor, but they are also less likely to exit poverty