Corticosterone selectively decreases humoral immunity in female eiders during incubation

Immunity is hypothesized to share limited resources with other physiological functions and this may partly account for the fitness costs of reproduction. Previous studies have shown that the acquired immunity of female common eider ducks (Somateria mollissima) is suppressed during their incubation, during which they entirely fast. Corticosterone was proposed to be an underlying physiological mechanism for such immunosuppression. Therefore, the current study aimed to assess the effects of exogenous corticosterone on acquired immunity in captive eiders. To this end, females were implanted with corticosterone pellets at different stages of their incubation fast. We measured total immunoglobulin levels, T-cell-mediated immune response, body mass and corticosterone levels in these females and compared them with those of control females prior to and after manipulation (i.e. corticosterone pellet implantation). To mimic corticosterone effects on body mass, we experimentally extended fasting duration in a group of females termed ;late fasters'..

The Common Tragedy of Regulations

Political Economy,

Point-record driving licence and road safety : an economic approach

Les permis de conduire à points sont aujourd'hui très largement utilisés pour faire respecter les politiques de sécurité routière, avec toutefois des mises en oeuvre diverses selon les pays et parfois à l'intérieur d'un même pays. Comme toute sanction non-monétaire, priver les contrevenants de leur permis permet aux autorités publiques de retirer de la route les individus dangereux et aussi de dissuader les conducteurs normaux d'enfreindre le code de la route. Nous analysons les caractéristiques souhaitables des mécanismes de permis à points et, en particulier, nous étudions s'ils devraient inclure des clauses de récupération des points perdus et des périodes probatoires. Nous envisageons également la possibilité d'un retrait immédiat du permis de conduire pour les infractions les plus graves.

On Debt Service and Renegotiation when Debt-holders Are More Strategic

The contingent claims analysis of the firm financing often presents a debt renegotiation game with a passive bank which does not use strategically its capability to force liquidation, contrary towhat is observed in practice. The first purpose of this paper is to introduce more strategic bank behaviour into the continuous-time model developed by Mella-Barral and Perraudin (1997) and Hackbarth, Hennessy, and Leland (2007). Its second purpose is to account for variations in the information obtained by the parties during the contract period. We show that with public information and private debt only, the optimal probability of debt renegotiation is fixed by the firm's anticipated liquidation value. When we add public debt and asymmetric information, the good-type firm may be tempted to mimic the bad-type to reduce its debt service. We show that to deter such mimicking, banks may sometimes refuse to renegotiate with strong firms having a low liquidation value. Our results are in line with the empirical observation that recovery rate at emergence of bankruptcy is function of the share of private debt in all the firm's debt and is relatively low.Debt service, debt renegotiation, recovery rate, strategic bank, bankruptcy, contingent claim

Practices

We examine an economy where professionals provide services to clients and where a professional can sell his practice to another. Professionals vary in quality, and clients in their need (or willingness-to-pay) for high-quality service. efficiency is measured as the number of matches between high-quality professionals and high-need clients. However, agent types are unobservable a priori. We find that trade in practices can facilitate the transmission of information about agent types; sometimes full efficiency is achieved. In cases where it is not, a tax on the sale of practices (based on the seller's age) can be used to achieve full efficiency. In addition, a ceiling on the price of services can be used to adjust the distribution of surplus between clients and professionals, while preserving efficiency.signaling, professional services, practices, goodwill

Healt care network formation and policyholders'welfare

We develop a model in which two insurers and two health care providers compete for a fixed mass of policyholders. Insurers compete in premium and offer coverage against financial consequences of health risk. They have the possibility to sign agreements with providers to establish a health care network. Providers, partially altruistic, are horizontally differentiated with respect to their physical address. They choose the health care quality and compete in price. First, we show that policyholders are better off under a competition between conventional insurance rather than under a competition between integrated insurers (Managed Care Organizations). Second, we reveal that the competition between a conventional insurer and a Managed Care Organization (MCO) leads to a similar equilibrium than the competition between two MCOs characterized by a different objective i.e. private versus mutual. Third, we point out that the ex ante providers' horizontal differentiation leads to an exclusionary equilibriumin which both insurers select one distinct provider. This result is in sharp contrast with frameworks that introduce the concept of option value to model the (ex post) horizontal differentiation between providers.Health Care Network, Horizontal Differentiation, HealthCare Quality