3,005 research outputs found
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, , 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:
ppm for the full dataset, versus ppm for the Webb {\it
et al.} data alone, both at the 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
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
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 , 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 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
() when this is the only free parameter, and not able to
constrain the model when also the symmetry breaking scale factor is
free to vary.Comment: Phys. Lett. B (in press
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
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
Qualidade de milho verde cultivado em sistemas de produção orgânico e convencional.
Avaliaram-se as características agronômicas e físico-químicas de milho verde cultivado em sistemas de produção orgânico e convencional. Utilizou-se o delineamento experimental inteiramente casualizado, em esquema fatorial 4 x 2, sendo quatro cultivares (AG 1051, BR 106, SWB 551 e VIVI), nos sistemas orgânico e convencional, com três repetições. As características agronômicas analisadas foram peso das espigas com palhas (PP) e despalhadas (PD), peso dos grãos (PG), peso do sabugo (PS), peso da palha (P), comprimento da espiga com palha (CE), percentual relativo de grãos (PRG), percentual relativo de palha (PRP) e percentual relativo de sabugo (PRS). Foram, ainda, analisados o teor de umidade e as características físico-químicas (pH, acidez titulável e sólidos solúveis totais) dos grãos verdes. As espigas produzidas no sistema convencional apresentaram PP, PD e PG superiores aos das espigas produzidas em sistema orgânico, para a cultivar AG 1051. O mesmo comportamento foi observado para o CE da cultivar SWB 551 e o PG da cultivar BR 106. No sistema convencional, a cultivar AG 1051 destacou-se nas características agronômicas avaliadas. Os valores médios de pH, diferentemente da acidez, foram superiores no cultivo orgânico. A cultivar SWB 551 apresentou maior percentual de sólidos solúveis entre as cultivares. Portanto, o sistema de produção influencia as principais características de qualidade do milho verde
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