5,271 research outputs found
The AGL Equation from the Dipole Picture
The AGL equation includes all multiple pomeron exchanges in the double
logarithmic approximation (DLA) limit, leading to an unitarized gluon
distribution in the small x regime. This equation was originally obtained using
the Glauber-Mueller approach. We demonstrate in this paper that the AGL
equation and, consequently, the GLR equation, can also be obtained from the
dipole picture in the double logarithmic limit, using an evolution equation,
recently proposed, which includes all multiple pomeron exchanges in the leading
logarithmic approximation. Our conclusion is that the AGL equation is a good
candidate for an unitarized evolution equation at small x in the DLA limit.Comment: 16 pages, 2 figures. Accepted for publication in Nuc. Phys.
Qualitative analysis of a scalar-tensor theory with exponential potential
A qualitative analysis of a scalar-tensor cosmological model, with an
exponential potential for the scalar field, is performed. The phase diagram for
the flat case is constructed. It is shown that solutions with an initial and
final inflationary behaviour appear. The conditions for which the scenario
favored by supernova type Ia observations becomes an attractor in the space of
the solutions are established.Comment: Latex file, 9 pages, 1 figur
Phase diagrams in kappa-carrageenan/locust bean gum systems
Gelation (Tgel) and melting (Tm) temperatures of kappa-carrageenan gels and 4:1 kappa-carrageenan/locust bean gum mixed gels, at different total potassium concentrations (CT), were determined by means of rheological (dynamic and viscosimetric) measurements. The log CT was linearly related to Tgel−1 and Tm−1. Differences found between both systems are discussed
A rheological characterization of kappa-carrageenan/galactomannan mixed gels: a comparison of locust bean gum samples
Mixed gels of kappa-carrageenan and locust bean gum (LBG) obtained from different varieties of Portuguese carob trees and commercial gums were compared. The viscoelastic properties of the gels were measured using dynamic parallel-plate geometry. Mixed gels at 1·0% of total polysaccharide concentration without addition of KCl showed, whatever the LBG sample, a synergistic maximum when the ratio of kappa-carrageenan to LBG was 80/20 The amplitude of this maximum varied with the LBG sample. The gels prepared at 0·3% total concentration with KCl added, showed a synergistic maximum at the same mixing ratio and the amplitude varied in a similar manner. Each sample was fractionated into the fraction soluble at 25°C and the fraction soluble at 90°C. Mixed gels of kappa-carrageenan with cold-water-soluble and hot-water-soluble fractions, and also with tara gum and guar gum were prepared at the 80/20 ratio. It was found that the synergistic maxima were related to the intrinsic viscosity and the M/G ratio. A linear relationship between the storage modulus G′max at the synergistic maximum and the product of the intrinsic viscosity and the square of the mannose to galactose ratio was found, suggesting that the synergistic mechanism can be ascribed to both the unsubstituted (galactose-free) regions of the galactomannan and the molecular weight
Exploring new ways of integration, visualization and interaction with Geotechnical and Geophysical Data
The work presented in this paper aims at exploring new ways of integrating, visualizing and interacting with geotechnical and geophysical data that may be more rich and interactive than those offered by most current Geographic Information Systems (GIS). Some visualization techniques enabling simultaneous visualization of the several data types available in our case study are proposed. Moreover, methods were developed to guide experts while defining layers and other relevant geological structures. The work is still in an early stage and is main goal has been assessing the validity and adequacy of the proposed techniques to the specific geotechnical and geophysical data under consideration.Universidade de Aveiro e Instituto Politécnico de Castelo Branc
Ranking and clustering of nodes in networks with smart teleportation
Random teleportation is a necessary evil for ranking and clustering directed
networks based on random walks. Teleportation enables ergodic solutions, but
the solutions must necessarily depend on the exact implementation and
parametrization of the teleportation. For example, in the commonly used
PageRank algorithm, the teleportation rate must trade off a heavily biased
solution with a uniform solution. Here we show that teleportation to links
rather than nodes enables a much smoother trade-off and effectively more robust
results. We also show that, by not recording the teleportation steps of the
random walker, we can further reduce the effect of teleportation with dramatic
effects on clustering.Comment: 10 pages, 7 figure
How impactful are public policies on environmental sustainability? Debating the Portuguese case of PO SEUR 2014–2020
Sustainable development is a key feature of national, European Union and global development strategies. The main research goal is to provide evidence on how impactful public policies on environmental sustainability in Portugal are at the regional level, in various policy areas. In this context, this paper analyses the main impacts of the Portuguese Operational Programme for Sustainability and Efficient Use of Resources (PO SEUR 2014–20). The research uses a territorial impact assessment (TIA) methodology (TARGET_TIA) to assess these impacts in five analytic dimensions (economy with low emissions, adaptation to climate change, risk prevention and management, environmental protection and resource efficiency) in the five mainland Portuguese NUTS 2. It concludes that, in overall terms, PO SEUR produced low to moderate positive impacts in all NUTS II and analysed dimensions, but it was particularly positive in measures fostering adaptation to climate change, and less impactful in measures supporting an economy with low emissions and resource efficiency in Portugal. Despite data limitations, the research provided adequate evidence that key public policies supporting environmental sustainability in Portugal are largely ineffective and inefficient in view of their policy goals and allocated funding. To turn this scenario around, the process of project selection needs to undergo significant improvements to better adjust the regional needs on environmental sustainability-related issues to the available funding. Moreover, on a policy strategic level, there needs to be support for a prosperous, modern, competitive and climate-neutral economy in Portugal via concrete actions exploring environmental capital and a green economy in urban areas.info:eu-repo/semantics/publishedVersio
- …