Policy experimentation, political competition, and heterogeneous beliefs

International audienceWe consider a two period model in which an incumbent political party chooses the level of a current policy variable unilaterally, but faces competition from a political opponent in the future. Both parties care about voters' payoffs, but they have different beliefs about how policy choices will map into future economic outcomes. We show that when the incumbent party can endogenously influence whether learning occurs through its policy choices (policy experimentation), future political competition gives it a new incentive to distort its policies — it manipulates them so as to reduce uncertainty and disagreement in the future, thus avoiding facing competitive elections with an opponent very different from itself. The model thus demonstrates that all incumbents can find it optimal to ‘over experiment’, relative to a counterfactual in which they are sure to be in power in both periods. We thus identify an incentive for strategic policy manipulation that does not depend on parties having conflicting objectives, but rather stems from their differing beliefs about the consequences of their actions

Comparison of Gene Repertoires and Patterns of Evolutionary Rates in Eight Aphid Species That Differ by Reproductive Mode

In theory, the loss of sexual reproduction is expected to result in the accumulation of deleterious mutations. In aphids, two main types of life cycle, cyclic and obligate parthenogenesis, represent respectively “sexual” and “asexual” reproductive modes. We used the complete pea aphid genome and previously published expressed sequence tags (ESTs) from two other aphid species. In addition, we obtained 100,000 new ESTs from five more species. The final set comprised four sexual and four asexual aphid species and served to test the influence of the reproductive mode on the evolutionary rates of genes. We reconstructed coding sequences from ESTs and annotated these genes, discovering a novel peptide gene family that appears to be among the most highly expressed transcripts from several aphid species. From 203 genes found to be 1:1 orthologs among the eight species considered, we established a species tree that partly conflicted with taxonomy (for Myzus ascalonicus). We then used this topology to evaluate the dynamics of evolutionary rates and mutation accumulation in the four sexual and four asexual taxa. No significant increase of the nonsynonymous to synonymous ratio or of nonsynonymous mutation numbers was found in any of the four branches for asexual taxa. We however found a significant increase of the synonymous rate in the branch leading to the asexual species Rhopalosiphum maidis, which could be due to a change in the mutation rate or to an increased number of generations implied by its change of life cycle

Default policies for global optimisation of noisy functions with severe noise

Global optimisation of unknown noisy functions is a daunting task that appears in domains ranging from games to control problems to meta-parameter optimisation for machine learning. We show how to incorporate heuristics to Stochastic Simultaneous Optimistic Optimization (STOSOO), a global optimisation algorithm that has very weak requirements from the function. In our case, heuristics come in the form of Covariance Matrix Adaptation Evolution Strategy (CMA-ES). The new algorithm, termed Guided STOSOO (STOSOO-G), combines the ability of CMA-ES for fast local convergence (due to the algorithm following the “natural” gradient) and the global optimisation abilities of STOSOO. We compare all three algorithms in the “harder” parts of the Comparing Continuous Optimisers on Black-Box Optimization Benchmarking benchmark suite, which provides a default set of functions for testing. We show that our approach keeps the best of both worlds, i.e. the almost optimal exploration/exploitation of STOSOO with the local optimisation strength of CMA-ES

Universal Quantum Cloning in Cavity QED

We propose an implementation of an universal quantum cloning machine [UQCM, Hillery and Buzek, Phys. Rev. A {\bf 56}, 3446 (1997)] in a Cavity Quantum Electrodynamics (CQED) experiment. This UQCM acts on the electronic states of atoms that interact with the electromagnetic field of a high $Q$ cavity. We discuss here the specific case of the $1 \to 2$ cloning process using either a one- or a two-cavity configuration

Suivi hydroclimatique dans une zone de crise humanitaire chronique - sud-est de Madagascar

International audienc

Quantum optics in the phase space - A tutorial on Gaussian states

In this tutorial, we introduce the basic concepts and mathematical tools needed for phase-space description of a very common class of states, whose phase properties are described by Gaussian Wigner functions: the Gaussian states. In particular, we address their manipulation, evolution and characterization in view of their application to quantum information.Comment: Tutorial. 23 pages, 1 figure. Updated version accepted for publication in EPJ - ST devoted to the memory of Federico Casagrand

A study of karst hydrosystem recharge at the parcel scale, using modeling and correlation analysis - Low noise underground laboratory of Rustrel site

La caractérisation des flux d’eaux qui rechargent réellement les hydrosystèmes souterrains reste un frein à la compréhension du fonctionnement hydrogéologique des milieux souterrains. Lors d’événements pluvieux, quelle part de l’eau est évapo-transpirée ? Quelle part est temporairement stockée dans le sol ? Ces incertitudes sont particulièrement fortes dans le cas de la recharge des milieux hétérogènes tel que le karst. En général, les calculs de recharge des hydrosystèmes karstiques se basent sur une représentation simplifiée de l’évapotranspiration qui considère seulement le climat et pas le fonctionnement de la végétation. Dans cette étude, un modèle de végétation permettant de simuler les transferts d’eaux entre le sol et l’atmosphère en contexte forestier (le modèle CASTANEA), a été appliqué à une parcelle de Chêne vert. L’infiltration efficace (un indicateur de la recharge) estimé avec CASTANEA a été comparée à celle estimée par des approches classiques ainsi qu’à des séries long terme de flux d’eaux souterraines (9 années). Les résultats de cette analyse révèlent que l’infiltration efficace modélisée à partir d’un modèle de végétation comme CASTANEA est plus satisfaisante que les approches classiques ne tenant pas compte du fonctionnement de la végétation. Ce travail ouvre des perspectives intéressantes pour mieux tenir compte du fonctionnement de la végétation et de l’usage du sol sur la recharge des hydrosystèmes karstiques.Assessing the recharge of underground hydrosystems remains an obstacle to understand their hydrologeological functioning. During a rain event, which part of the rain is evapotranspired ? And how much is temporarily stored within the soil ? These questions are particularly relevant in heterogeneous media such as karst hydrosystems. Currently, the models used to compute recharge of karst hydrosystems, rely on simplistic formulations of evapotranspiration that do not account for vegetation functioning. In this study, we used the vegetation process based model CASTANEA, which is designed to compute water transfer between soil, plant and atmosphere. We computed effective infiltration (an index of recharge) with CASTANEA and with other classical approach (based on precipitation minus ETP), and for a welldocumented holm oak site in Provence. Our results provide evidences that effective infiltration computed with CASTANEA yield more satisfactory correlation with measured outflow than simulations based on the classical approach. Our results provide a promising way to improve the simulation of karst hydrosystem recharge