Large scale correlations of quasar polarisation vectors: Hints of extreme scale structures?

A survey measuring quasar polarization vectors has been started in two regions towards the North and South Galactic Poles. Here, We review the discovery of significant correlations of orientations of polarization vectors over huge angular distances. We report new results including a larger sample of the quasars confirming the existence of coherent orientations at redshifts z>1.Comment: Proc. of Astronomical Polarimetry - Current Status and Future Directions March 15-19, 2004. Waikoloa Beach Marriott, Hawaii. 5 pages, 3 figure

The role of motor response in implicit encoding: Evidence from intertrial priming in pop-out search

AbstractPerception and motor control jointly act to meet our current needs. Recent evidence shows that the generation of motor action significantly affects perception. Here, we examined the role of motor response in inter-trial priming, namely, in Priming of Pop-out (PoP): when searching for a singleton target, performance is improved when the target and distractors features repeat on consecutive search trials than when they switch. Although recent studies have shown an interaction between motor response and PoP, the role of motor action on priming has not been fully characterized. Here we investigated whether motor action is necessary during encoding, for PoP to be observed. On go trials, observers searched for a color singleton target and responded to its shape, while on no-go trials they passively watched the display instead of responding to the target. We observed PoP even when the previous trial had been a no-go trial, suggesting that encoding of search-relevant attributes in pop-out displays is not contingent on motor response. Nevertheless, the repetition effect was larger after a go trial than after a no-go trial, supporting the dual-stage model of PoP, according to which this effect involves both a perceptual and a motor component

The role of search difficulty in intertrial feature priming

AbstractPrevious research has shown that intertrial repetition of target and distractors task-relevant properties speeds visual search performance, an effect known as priming of pop-out (PoP). Recent accounts suggest that such priming results, at least in part, from a mechanism that speeds post-selectional, response-related processes, the marker of which is an interaction between repetition of the target and distractor features and repetition of the response from the previous trial. However, this response-based component of inter-trial priming has been elusive, and it remains unclear what its boundary conditions might be. In addition, what information is represented in the episodic memory traces that underlie the response-based component has not yet been characterized.Here, we show that the response-based component of feature priming reflects an episodic memory retrieval mechanism that is not mandatory or automatic but may be described as a heuristic that subjects sometimes use, in particular when the overall difficulty of the search task is high. In addition, we show that the conjunction of the target and distractor features forms the context that is reactivated during episodic retrieval. Finally, we show that target–distractor discriminability is an important modulator of the selection-based component. The findings are discussed within the framework of the dual-stage model of inter-trial priming (Lamy, Yashar, & Ruderman, 2010)

Prix versus quantités : Les politiques environnementales d’incitation au développement des énergies renouvelables

La confirmation du risque de changement climatique et la volonté affichée des Etats européens de poursuivre des objectifs ambitieux de production d’électricité renouvelable pour y répondre invitent à s’interroger sur l’efficacité comparée des instruments d’incitation utilisés. Ceux-ci sont clairement des instruments homologues de ceux utilisés par les politiques environnementales. Le choix entre les instruments jouant sur les quantités - fixation d’objectifs nationaux et enchères concurrentielles, ou bien imposition de quotas et échanges de certificats verts -, et les instruments jouant sur les prix - tarifs d’achats administrés - relève du même type de débat que pour ces politiques. Toutefois l’objet de l’intervention publique est particulier : il est de stimuler le changement technique et d’accélérer les apprentissages technologiques en vue d’amener les techniques renouvelables vers la zone de compétitivité avec les techniques classiques après internalisation des coûts environnementaux. La comparaison des instruments doit donc être posée en relation avec les caractéristiques des processus d’innovation et des conditions d’adoption - incertitudes sur les courbes de coût, dynamiques d’apprentissage - qui conduisent à se référer aussi à des critères d’efficience dynamique.Pour ce faire on examine l’efficacité des différents cadres incitatifs au développement des énergies renouvelables, à la fois d’un point de vue théorique en opposant les approches par les prix à celles par les quantités, et d’un point de vue pratique en se référant aux expériences concrètes de mise en œuvre de ces différents instruments. Le papier conclut à l’efficacité plus grande du système de prix administrés comparé au dispositif d’enchères, mais met en évidence les qualités théoriques de l’approche par les certificats verts qui devront être confirmées par la pratique, compte tenu de l’influence des règles et des structures de marché sur les performances de ce type d’approche

L'intégration de la production intermittente dans les marchés électriques libéralisés : des surcoûts techniques aux pénalités économiques imposées par les règles de fonctionnement des marchés

Les problèmes que soulève l'intégration de la production intermittente sont de nature technique (risque de non disponibilité à la pointe, besoins de réserve supplémentaires) mais les modalités de fonctionnement des marchés électriques lui imposent des pénalités économiques qui dépassent largement ces surcoûts techniques. Dans ce texte, les auteurs examinent la nature des problèmes techniques posés par l'intermittence et les surcoûts qui en résultent, puis analysent l'origine des pénalités économiques qu'impose le fonctionnement des marchés électriques libéralisés, en prenant notamment l'exemple du marché britannique, le New Electricity Trading Arrangement (NETA). Il apparaît que les règles de fonctionnement des marchés peuvent dans certains cas entrer en contradiction avec les objectifs de promotion de la production d'électricité d'origine renouvelable. Deux types de solutions sont alors envisageables : un aménagement des règles pour en limiter l'impact sur la production intermittente ou un traitement collectif de l'ajustement, pour la production d'origine renouvelable, tel qu'il existe sur le marché nordique de l'électricité.énergie renouvelable;intermittence;éolien;marchés électriques;libéralisation

Selective and Collaborative Optimization Methods for Plasmonics: A Comparison

International audienceIn this paper, we optimize the size parameters of hollow nanospheres and nanoshells used in cancer photothermal therapy and we focus on two practical therapy cases: the visible range for shallow cancer and the near infrared for deep cancer. For this, we consider analytical models: the Mie theory for coated spheres. The investigated optimization methods are the Evolutionary Method (EM) and the Particle Swarm Optimization (PSO) which are based on competitiveness and collaborative algorithms, respectively. A comparative study is achieved by checking the efficiency of the optimization methods, to improve the nanoparticles efficiency

Electromagnetic Heat-induced in Meso-structures: Computation of Temperature in Metallic Dimers

International audienceThe illumination of a dimer metallic nanostructure is known to produce an in- tense source of light, with nanometric size. This con¯nement of light in the gap between the two material structures can induce an increase of the absorption of the electromagnetic energy in the nanaoantenna itself, and therefore its warm-up. The multiphysics problem associated to this photo-thermal e®ect is modeled through a Finite Element Method (FEM). This contribu- tion consists in computing both the electromagnetic ¯eld and the temperature, and discussing the in°uence of the gap, in the case of a bow-tie nanoantenna. The applications could be the development of nanodevices with thermal properties

Perceptual Processing is Not Spared During the Attentional Blink

Identification of the second of two targets is impaired when these appear within 500 ms of each other. This phenomenon, known as the attentional blink (AB) is thought to reflect disrupted post-perceptual processing. Yet, decisive empirical support for this claim is lacking. We measured the depth of the AB, while manipulating the second target’s reporting feature. We reasoned that if perceptual processing is unaffected by the blink, all the features of the blinked target should have equal access to working memory. In contrast with this prediction, we found identity and semantic-category reports to be more severely impaired by the blink than color reports, although baseline performance was similar in the two report conditions. These findings suggest that high-level features are more poorly represented in working memory than low-level features during the blink. We conclude that the attentional blink disrupts perceptual processing. Implications for contemporary models of the attentional blink are discussed