Two-sided reputation in certification markets

We consider a market where privately informed sellers resort to certification to overcome adverse selection. There is uncertainty about the certifier's ability to generate accurate information. The profit of a monopolistic certifier is an inverted U-shaped function of his reputation for accuracy: being perceived as more precise allows to attract more good sellers but a high expected precision also deters bad sellers. Since the certifier tries to reach a balanced reputation to attract both types, reputation has a disciplining effect when the certifier is perceived as insufficiently accurate, but gives incentives to decrease precision when he is perceived as “too" accurate. The impact of competition depends on whether sellers “multihome" or “singlehome". Under singlehoming, certifiers compete to attract good sellers, which makes higher reputation more valuable. Multihoming makes higher reputations less desirable because the competitor exerts a negative externality by providing extra information. Therefore, singlehoming attenuates bad reputation effects, while multihoming exacerbates inefficiencies

Counter-rotation in an orbitally shaken glass of beer

Swirling a glass of wine induces a rotating gravity wave along with a mean flow rotating in the direction of the applied swirl. Surprisingly, when the liquid is covered by a floating cohesive material, for instance a thin layer of foam in a glass of beer, the mean rotation at the surface can reverse. This intriguing counter-rotation can also be observed with coffee cream, tea scum, cohesive powder, provided that the wave amplitude is small and the surface covering fraction is large. Here we show that the mechanism for counter-rotation is a fluid analog of the rolling without slipping motion of a planetary gear train: for sufficiently large density, the covered surface behaves as a rigid raft transported by the rotating sloshing wave, and friction with the near-wall low-velocity fluid produces a negative torque which can overcome the positive Stokes drift rotation induced by the wave.Comment: To appear in EPL (2018

The Legislative Role of the French Parliament in Crisis Management

In examining the subject of crisis management, I shall reflect on the role of the French Assembly—as I have seen it—over the past eleven years and then consider whether this role is a proper one

Entangled single-wire NiTi material: a porous metal with tunable superelastic and shape memory properties

NiTi porous materials with unprecedented superelasticity and shape memory were manufactured by self-entangling, compacting and heat treating NiTi wires. The versatile processing route used here allows to produce entanglements of either superelastic or ferroelastic wires with tunable mesostructures. Three dimensional (3D) X-ray microtomography shows that the entanglement mesostructure is homogeneous and isotropic. The thermomechanical compressive behavior of the entanglements was studied using optical measurements of the local strain field. At all relative densities investigated here ($\sim$ 25 - 40$\%$), entanglements with superelastic wires exhibit remarkable macroscale superelasticity, even after compressions up to 25$\%$, large damping capacity, discrete memory effect and weak strain-rate and temperature dependencies. Entanglements with ferroelastic wires resemble standard elastoplastic fibrous systems with pronounced residual strain after unloading. However, a full recovery is obtained by heating the samples, demonstrating a large shape memory effect at least up to 16% strain.Comment: 31 pages, 10 figures, submitted to Acta Materiali

Chassagne – Abbaye de Mégemont

Identifiant de l'opération archéologique : 134 Date de l'opération : 2006 (FP) La présente opération fait suite à des relevés d’élévation effectués en août 2005 (BSR 2005, p. 122-124). Il s’agissait alors d’établir la chronologie relative des différentes unités de construction du mur pignon du croisillon nord du transept de l’église de Mègemont. Celui-ci constitue un véritable noeud chronologique entre l’espace purement ecclésial de l’établissement monastique et ses parties conventuelles. En ..

Recy – Déviation de Recy

Identifiant de l'opération archéologique : 4852 Date de l'opération : 2004 (EX) Ce diagnostic a été réalisé sur une faible emprise en largeur (16 m), destinée à recevoir une route départementale. Cette intervention complète les travaux de prospections mécaniques menés à Recy, Les Champs du Moulin, par Raphaël Durost. Elle a permis de mettre en évidence plusieurs vestiges archéologiques. Tout d'abord des fosses quadrangulaires d'extraction de graviers ont été identifiées sur l'emprise. Leurs ..