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

Searching for sectoral patterns of innovation in european manufacturing industry

The present paper is conducted under the research project “Enterprise of the Future: Trends and Scenarios towards Competitiveness” which attempts to disclosure determinants of future enterprise competitiveness. Innovation is not only a must today but also an imperative in future competitiveness scenarios. In modern evolutionary economics it is argued that sector-specific factors are one of the key factors explaining innovative behaviour and performance of firms. Several contributions have pointed that industries largely differ in terms of knowledge base and technological sources, opportunities and appropriation of innovative activities, technological trajectories and firms’ strategies. Using as background Pavitt’s taxonomy, this paper explores the nature, extent and sources of variety of innovation in the manufacturing industry, aiming at identifying common patterns across industries, and sectoral patterns across countries. This paper presents evidence based on the aggregated results of the last IV Community Innovation Survey released by EUROSTAT (CIS4), for which data is available for a number of industries and countries

PRESSURE DROP IN A SPOUTED BED OF CORK STOPPERS

The spouted bed is a particular type of fluidized bed which is well suited forthe handling of large size particles like cork stoppers. It is commonly usedfor the drying of granulates and the present work is the first part of a studyconcerning the drying of cork stoppers in a laboratory scale spouted bed reactor. The study considers two stoppers size, one the port wine stopper and another small size stopper. The choice of these smaller sizes was imposed by the small dimensions of the reactor. In this preliminary set of experiments the fluid-dynamics regime of the particular two phase flow was characterized. For different experimental situations covering several air flows and temperatures typical of cork drying operations the evolution of pressure drop was evaluated and a correlation for the minimum spouting velocity was obtained

DILUTE PHASE VERTICAL PNEUMATIC CONVEYING OF CORK STOPPERS

The pneumatic conveying of cork stoppers is used in the cork processingindustries with equipments designed and built purely on an empirical basis.Experimental studies to characterize this type of pneumatic transportationhave been, so far, oriented towards the study of horizontal conveying processes, either for steady state transportation or for the acceleration zone.However studies were carried out on the determination of the pressure dropon vertical transportation of cork stoppers. Here the experimental apparatusand procedure are described, and the first experimental data that have beenobtained are shown. In consequence a simple correlation for the pressure drop in the steady state region of the conveying pipe is proposed. Thecorrelation is a function of dimensionless parameters used to characterizethe two phase flow under analysis. Three standard stoppers sizes and a single pipe diameter were used in the experiments, all carried out at ambient temperature