Gravitational wave background in perfect fluid quantum cosmologies

We discuss the gravitational wave background produced by bouncing models based on a full quantum evolution of a universe filled with a perfect fluid. Using an ontological interpretation for the background wave function allows us to solve the mode equations for the tensorial perturbations, and we find the spectral index as a function of the fluid equation of state.Comment: 12 pages, 5 figures, to appear in Phys. Rev. D (2006

Updated constraints on spatial variations of the fine-structure constant

Recent work by Webb {\it et al.} has provided indications of spatial variations of the fine-structure constant, $\alpha$, at a level of a few parts per million. Using a dataset of 293 archival measurements, they further show that a dipole provides a statistically good fit to the data, a result subsequently confirmed by other authors. Here we show that a more recent dataset of dedicated measurements further constrains these variations: although there are only 10 such measurements, their uncertainties are considerably smaller. We find that a dipolar variation is still a good fit to the combined dataset, but the amplitude of such a dipole must be somewhat smaller: $8.1\pm1.7$ ppm for the full dataset, versus $9.4\pm2.2$ ppm for the Webb {\it et al.} data alone, both at the $68.3\%$ confidence level. Constraints on the direction on the sky of such a dipole are also significantly improved. On the other hand the data can't yet discriminate between a pure spatial dipole and one with an additional redshift dependence.Comment: 10 pages, 4 figure

Constraining spatial variations of the fine-structure constant in symmetron models

We introduce a methodology to test models with spatial variations of the fine-structure constant $\alpha$, based on the calculation of the angular power spectrum of these measurements. This methodology enables comparisons of observations and theoretical models through their predictions on the statistics of the $\alpha$ variation. Here we apply it to the case of symmetron models. We find no indications of deviations from the standard behavior, with current data providing an upper limit to the strength of the symmetron coupling to gravity ($\log{\beta^2}<-0.9$) when this is the only free parameter, and not able to constrain the model when also the symmetry breaking scale factor $a_{SSB}$ is free to vary.Comment: Phys. Lett. B (in press

Exploring economic and policy determinants of FDI. A panel data analysis

During the past decades, the world economy has witnessed a dramatic surge in foreign direct investment. There is increasing competition among economies in attracting inflows of FDI. There has been renewed research interest in trying to detect what are the economic and political conditions that make a local economy an attractive destination for FDI inflows. Hence, in this paper we investigate macroeconomic and locational variables that may influence the level of FDI in a group of countries as a whole. In this paper we explore not only economic but also policy variables in terms of trade policy and regulation, and their effects on foreign direct investment. The evidence is captured by panel data analysis, which pools together 29 countries over the period 1990-2005. Overall our research shows that the distribution of FDI across countries is strongly determined by economic fundamentals and broad policies affecting foreign owned and domestic firms alike. Strategic and endurable horizontal policies, education and training in particular, can do much for the latter. There is scope for policies that are costless in the sense of having no immediate budgetary implications, namely the reduction of remaining impediments to trade

The Influence of the Distributor Plate on the Bottom Zone of a Fluidized Bed Approaching the Transition from Bubbling to Turbulent Fluidization

The dynamics of the bottom zone of a narrow fluidized bed, from bubbling to turbulent regimes, was studied in a cold model of 0.1 m i.d. and 1.3 m high. Tested distributor types were perforated perspex plates, with six different perforation grids, metallic mesh and porous ceramic, with pressures drops ranging from 0.05 to 350 kPa, corresponding to superficial air velocities from 0.1 to 2.3m s-1. Group B silica ballotini, within the range 0.355-0.425 mm, were used as bed material. The experimental data consisted of pressure drop and absolute pressure fluctuating signals, together with visual observations. The bottom zone presented a dynamic condition that produced higher pressure drop values than those expected with the incipient fluidization condition, particularly for the distributor plates with a higher open area. A simple model is used to describe the axial solids distribution and the dynamics characteristics of the voids created in that zone, and an attempt is made to differentiate the bubble voidage from that of the dense phase, with a value of through flow estimated in a systematic way.http://www.sciencedirect.com/science/article/B8JGF-4RT04WJ-5/1/35ae43b23db71e43caf98b5be93bab0

Pour une amélioration du français chez les garçons

Recherche subventionnée par le ministère de l’Éducation, du Loisir et du Sport du gouvernement du Québec, dans le cadre de son Programme d’aide à la recherche sur l’enseignement et l’apprentissage (PAREA)Contributions iii; Remerciements v; Sommaire vii; Listes des figures et des tableaux xi; Listes des abréviations et des symboles xiii; Introduction 1; Première partie Préalables théoriques et méthodologiques 5; Chapitre 1 Problématique 7; Portrait de Nicolas 8; Définition du problème et état de la question 11; Les garçons et les mesures d’aide en français 20; Objectifs 29; Chapitre 2 Méthodologie 33; Portrait de Juan 34; Devis de recherche 38; Analyse de la situation 39; Ébauche des cahiers de charges et des portraits 40; Conception des objets 48; Préparation technique et construction des prototypes 49; Mise au point des objets 51; Deuxième partie Objets pédagogiques 53; Chapitre 3 Objet pédagogique Au lieu de lire 55; Portrait d’Alessandro 56; Présentation 60; Cahier des charges 63; Mise en oeuvre 74; Évaluation et discussion 88; Chapitre 4 Objet pédagogique Français, futur simple? 109; Portrait de Samuel 110; x; Présentation 113; Cahier des charges 115; Mise en oeuvre 123; Évaluation et discussion 137; Conclusion 145; Portrait de Tristan 158; Bibliographie 163; Annexe 1 Synthèse des résultats du premier temps de la recherche (2000-2003) 173; Annexe 2 Grille de codage préalable 179; Annexe 3 Matrice 189; Annexe 4 Fiches pour les observations de terrain 193; Annexe 5 Tableau de régression extrait de Lapostolle, Massé et Pinho, 2003, p. 91 199; Annexe 6 Tableau de régression extrait de Lapostolle, Massé et Pinho, 2003, p. 87 201; Annexe 7 Corpus français 203; Annexe 8 Ouvrages de référence . 227; Annexe 9 Feuillet parcours + contenu 229; Annexe 10 Feuillet parcours + mesures 233

Heat conduction in the hollow sphere with a power-law variation of the external heat transfer coefficient

The conduction phenomenon in an insulated sphere is re-worked through a dimensionless approach, where the heat transfer coefficient dependence on the external radius and on the surface temperature, as in the case of forced and free convection, is taken into account. Assuming a power law variation of the convection coefficient [1, 2], and using the results of Sparrow [3], equations and graphs for the most important dimensionless parameters are presented. The developed equations show, for example, that as the insulation thickness increases the heat transfer rate tends to a positive value, independent of the considered case: constant convection coefficient, forced or free convection.http://www.sciencedirect.com/science/article/B6V3J-42MP1M2-3/1/6228c6d77bbaac53e7833e6cd67d8ef