Fact Finding Trips to Italy: An experimental investigation of voter incentives

This paper addresses the interaction of voter information and seniority on electoral accountability. We test whether information leads voters to be less tolerant of moral hazard in a legislative system favoring seniority. A simple game theoretic model is used to predict outcomes in a pork-barrel experiment where subjects act as legislators and voters. Senior legislators have an advantage in providing transfers which presents the opportunity to shirk where legislators can enrich themselves at the expense of voters. Voter information about incumbent behavior is varied across experimental treatments. We find that accountability increases when voters can compare their own legislator’s behavior to the behavior of others. Despite the fact that voters succumb to the incentives of seniority, information is effective in deterring legislator shirking.voting, experiments, information, principal-agent problem

Editorial: Mémoires et migrations en Afrique de l'Ouest et en France

Jusque dans les années 1990, la thématique « mémoires et migrations » a surtout été abordée dans le cadre des Diaspora Studies anglo-saxonnes. La discussion s’est longtemps centrée sur la question de la diaspora africaine et de son identité en Amérique du Nord qui a vu s’opposer les défenseurs d’un projet ontologique de la diaspora africaine (Echeruo, 1999) et les partisans du « Black Atlantic ». Parallèlement, se sont également développées les Memory Studies. Intimement liées, au départ, à l..

Estimating hyperparameters and instrument parameters in regularized inversion. Illustration for SPIRE/Herschel map making

We describe regularized methods for image reconstruction and focus on the question of hyperparameter and instrument parameter estimation, i.e. unsupervised and myopic problems. We developed a Bayesian framework that is based on the \post density for all unknown quantities, given the observations. This density is explored by a Markov Chain Monte-Carlo sampling technique based on a Gibbs loop and including a Metropolis-Hastings step. The numerical evaluation relies on the SPIRE instrument of the Herschel observatory. Using simulated and real observations, we show that the hyperparameters and instrument parameters are correctly estimated, which opens up many perspectives for imaging in astrophysics

A Time-Evolving 3D Method Dedicated to the Reconstruction of Solar plumes and Results Using Extreme Ultra-Violet Data

An important issue in the tomographic reconstruction of the solar poles is the relatively rapid evolution of the polar plumes. We demonstrate that it is possible to take into account this temporal evolution in the reconstruction. The difficulty of this problem comes from the fact that we want a 4D reconstruction (three spatial dimensions plus time) while we only have 3D data (2D images plus time). To overcome this difficulty, we introduce a model that describes polar plumes as stationary objects whose intensity varies homogeneously with time. This assumption can be physically justified if one accepts the stability of the magnetic structure. This model leads to a bilinear inverse problem. We describe how to extend linear inversion methods to these kinds of problems. Studies of simulations show the reliability of our method. Results for SOHO/EIT data show that we are able to estimate the temporal evolution of polar plumes in order to improve the reconstruction of the solar poles from only one point of view. We expect further improvements from STEREO/EUVI data when the two probes will be separated by about 60 degrees

Efficient Variational Bayesian Approximation Method Based on Subspace optimization

International audienceVariational Bayesian approximations have been widely used in fully Bayesian inference for approx- imating an intractable posterior distribution by a separable one. Nevertheless, the classical variational Bayesian approximation (VBA) method suffers from slow convergence to the approximate solution when tackling large-dimensional problems. To address this problem, we propose in this paper an improved VBA method. Actually, variational Bayesian issue can be seen as a convex functional optimization problem. The proposed method is based on the adaptation of subspace optimization methods in Hilbert spaces to the function space involved, in order to solve this optimization problem in an iterative way. The aim is to determine an optimal direction at each iteration in order to get a more efficient method. We highlight the efficiency of our new VBA method and its application to image processing by considering an ill-posed linear inverse problem using a total variation prior. Comparisons with state of the art variational Bayesian methods through a numerical example show the notable improved computation time

A Multi-Level Context-Dependent Prosodic Model applied to duration modeling

International audienceon the estimation of prosodic parameters on a set of well defined linguistic units. Different linguistic units are used to represent different scales of prosodic variations (local and global forms) and thus to estimate the linguistic factors that can explain the variations of prosodic parameters independently on each level. This model is applied to the modeling of syllablebased durational parameters on two read speech corpora - laboratory and acted speech. Compared to a syllable-based baseline model, the proposed approach improves performance in terms of the temporal organization of the predicted durations (correlation score) and reduces model's complexity, when showing comparable performance in terms of relative prediction error. Index Terms : speech synthesis, prosody, multi-level model, context-dependent model

Experimental study of internal wave generation by convection in water

We experimentally investigate the dynamics of water cooled from below at 0^oC and heated from above. Taking advantage of the unusual property that water's density maximum is at about 4^oC, this set-up allows us to simulate in the laboratory a turbulent convective layer adjacent to a stably stratified layer, which is representative of atmospheric and stellar conditions. High precision temperature and velocity measurements are described, with a special focus on the convectively excited internal waves propagating in the stratified zone. Most of the convective energy is at low frequency, and corresponding waves are localized to the vicinity of the interface. However, we show that some energy radiates far from the interface, carried by shorter horizontal wavelength, higher frequency waves. Our data suggest that the internal wave field is passively excited by the convective fluctuations, and the wave propagation is correctly described by the dissipative linear wave theory