Cosmology with a Continuous Tower of Scalar Fields

We study the cosmological evolution for a universe in the presence of a continuous tower of massive scalar fields which can drive the current phase of accelerated expansion of the universe and, in addition, can contribute as a dark matter component. The tower consists of a continuous set of massive scalar fields with a gaussian mass distribution. We show that, in a certain region of the parameter space, the {\it heavy} modes of the tower (those with masses much larger than the Hubble expansion rate) dominate at early times and make the tower behave like the usual single scalar field whose coherent oscillations around the minimum of the potential give a matter-like contribution. On the other hand, at late times, the {\it light} modes (those with masses much smaller than the Hubble expansion rate) overcome the energy density of the tower and they behave like a perfect fluid with equation of state ranging from 0 to -1, depending on the spectral index of the initial spectrum. This is a distinctive feature of the tower with respect to the case of quintessence fields, since a massive scalar field can only give acceleration with equation of state close to -1. Such unique property is the result of a synergy effect between the different mass modes. Interestingly, we find that, for some choices of the spectral index, the tower tracks the matter component at high redshifts (or it can even play the role of the dark matter) and eventually becomes the dominant component of the universe and give rise to an accelerated expansion.Comment: 13 pages, 8 figures. V2: minor changes to match published versio

Relativistic deuteron structure function at large Q^2

The deuteron deep inelastic unpolarized structure function F_2^D is calculated using the Wilson operator product expansion method. The long distance behaviour, related to the deuteron bound state properties, is evaluated using the Bethe-Salpeter equation with one particle on mass shell. The calculation of the ratio F_2^D/F_2^N is compared with other convolution models showing important deviations in the region of large x. The implications in the evaluation of the neutron structure function from combined data on deuterons and protons are discussed.Comment: 7 pages, 1 ps figure, RevTeX source, 1 tar.gz file. Submited to Physical Letter

A Multiple Criteria Framework to Evaluate Bank Branch Potential Attractiveness

Remarkable progress has occurred over the years in the performance evaluation of bank branches. Even though financial measures are usually considered the most important in assessing branch viability, we posit that insufficient attention has been given to other factors that affect the branches’ potential profitability and attractiveness. Based on the integrated used of cognitive maps and MCDA techniques, we propose a framework that adds value to the way that potential attractiveness criteria to assess bank branches are selected and to the way that the trade-offs between those criteria are obtained. This framework is the result of a process involving several directors from the five largest banks operating in Portugal, and follows a constructivist approach. Our findings suggest that the use of cognitive maps systematically identifies previously omitted criteria that may assess potential attractiveness. The use of MCDA techniques may clarify and add transparency to the way trade-offs are dealt with. Advantages and disadvantages of the proposed framework are also discussed.

Demand, Supply and Markup Fluctuations

The cyclical behavior of markups is at the center of macroeconomic debate on the origins of business-cycle fluctuations and policy effectiveness. In theory, markups may fluctuate endogenously with the business cycle due to sluggish price adjustment or to deeper motives affecting the price-elasticity of demand faced by individual producers. In this article we make use of a large Örm- and product-level panel of Portuguese manufacturing Örms in the 2004-2010 period. The biggest empirical challenge is to separate supply (TFP) from demand shocks. Our dataset allows to do so, by containing information on product-level prices at a yearly frequency. Furthermore, markups are mismeasured when calculated with the labor share. We use the share of intermediate inputs instead. Our main results suggest that markups are pro-cyclical with TFP shocks and generally counter-cyclical with demand shocks. We also show how markups become procyclical if the markup is obtained using the labour share instead of intermediate inputs. Adjustment costs create a wedge between the labour share and the actual markup which explain the observed correlations.N/

Demand, supply and markup fluctuations

Markup cyclicality has been central for debating policy effectiveness and understanding business cycle fluctuations. However, there are two empirical challenges: separating supply (TFP) from demand shocks, and properly measuring the markups. In this article, we use a panel of Portuguese manufacturing firms for 2004-2014. Since it contains information on product- level prices, we can separate supply from demand shocks. We overcome the markup measurement by using the share of intermediate inputs on revenues, instead of the labor share. Our results suggest that markups are pro-cyclical with TFP shocks, and counter-cyclical with demand shocks. We also show that labor-based markups are pro-cyclical.info:eu-repo/semantics/publishedVersio

Traffic noise changes due to water on porous and dense asphalt surfaces

The standards for the environmental quality required by the European Community are very demanding in what concerns traffic noise. The interaction tire/road is undoubtedly one of the main sources of traffic noise. Nevertheless, standards do not account for the increase in the noise level caused by rain falling onto road surfaces. Therefore, the aim of this work is to study the effects of water on pass-by noise since the weather is rainy about 25 per cent of the year in Portugal. Thus, it addresses two currently used pavement surfaces, porous asphalt and dense asphalt, constructed in a motorway. A version of the Statistical Pass-By Method was used to assess noise levels with dry and wet surfaces, using a selected set of heavy and light vehicles. The results include analysis of the statistical pass-by index, pressure noise levels and noise spectrum. Noise levels increase significantly with the presence of water, shifting the overall noise by 4 dB(A). The benefits of porous asphalt are null for heavy vehicles, particularly at high speeds. CE Database subject headings: traffic noise, water, porous asphalt, dense asphalt, statistical pass-by method, noise level, noise spectrum.(undefined