The lattice Landau gauge gluon propagator: lattice spacing and volume dependence

The interplay between the finite volume and finite lattice spacing is investigated using lattice QCD simulations to compute the Landau gauge gluon propagator. Comparing several ensembles with different lattice spacings and physical volumes, we conclude that the dominant effects, in the infrared region, are associated with the use of a finite lattice spacing. The simulations show that decreasing the lattice spacing, while keeping the same physical volume, leads to an enhancement of the infrared gluon propagator. In this sense, the data from $\beta=5.7$ simulations, which uses an $a \approx 0.18$ fm, provides a lower bound for the infinite volume propagator.Comment: Final version to appear in Phys Rev

Bathymetric surveys from SAR satellite images using wavelets

When waves propagate in coastal areas they sufer changes in the wavelength and wave direction resulting from the interaction with the sea bottom. In SAR images, the waves can be identify through variations in the gray tones of the image, making it possible to infer the bathymetry from the variations in the wavelength. Commonly, the fast Fourier transform (FFT) is used to estimate the wavelength in domains close to the coast, recognizing, however, that this method has some limitations, mainly for small depths. To overcome the limitations of FFT, this work uses wavelet spectral analysis to estimate bathymetric data. The new image processing methodology shows positive and promising results for mapping shallow marine environments.Peer Reviewe

Nearshore Bathymetry Retrieval from Wave-Based Inversion for Video Imagery

A wavelet-based method for bathymetry retrieval using a sequence of static images of the surface wave field, as obtained from video imagery, is proposed. Synthetic images of the water surface are generated from a numerical Boussinesq type model simulating the propagation of irregular waves. The spectral analysis is used to retrieve both wave periods and wavelengths by evaluating the spectral peaks in the time and spatial domains, respectively. The water depths are estimated using the linear dispersion relation and the results are validated with the model’s bathymetry. To verify the proposed methodology, 2D and 3D simulations considering effects of wave shoaling and refraction were performed for different sea conditions over different seafloors. The method’s ability to reproduce the original bathymetry is shown to be robust in intermediate and shallow waters, being also validated with a real case with images obtained with a shore-based video station. The main improvements of the new method compared to the consideration of a single image, as often used in Satellite Derived Bathymetry, is that the use of successive images enables the consideration of different wave periods, improving depth estimations and not requiring the use of subdomains or filters. This image processing methodology shows very positive results to provide bathymetry maps for shallow marine environments and can be useful to monitor the nearshore with high time- and space-resolution at low cost.This research was funded by Direção Geral da Política do Mar, through projectNAVSAFETY of the Fundo Azul program. Thanks are due to FCT/MCTES (PT) for the financial support to CESAM (UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020), through national funds and to the project Space for Shore funded through EOEP 5 Coastal Erosion Program (ESA/AO/1-9219/18/I-LG).info:eu-repo/semantics/publishedVersio

Modificação de betumes com aditivos líquidos para aplicação em países tropicais

A modificação de betumes é uma das soluções mais utilizadas na pavimentação, sobretudo em países com climas quentes, pois permite minimizar problemas tais como o fendilhamento, o envelhecimento do betume, e em especial as deformações permanentes. Este trabalho visa estudar uma solução para modificação do betume de modo a contornar os problemas acima indicados do betume puro existente nesses países. Para isso foram utilizados dois aditivos líquidos, SBR líquido e ácido polifosfórico (PPA), e foram estudadas diferentes percentagens de adição dos mesmos em betumes puros, de modo a selecionar o aditivo com mais potencial e a percentagem em que devia ser incorporado.Fundos QREN, através da ANI, no âmbito do projeto Tropical-Pav – “Soluções de Pavimentação Rodoviária para Climas Tropicais”, num consórcio constituído por duas empresas e quatro entidades do Sistema Científico e Tecnológico Nacional (SCTN), nomeadamente Elevo Grupo, Mota-Engil Engenharia e Construção, Instituto Superior Técnico, Laboratório Nacional de Engenharia Civil, Universidade de Coimbra e Universidade do Minho

Can the distributional impacts of macroeconomic shocks be predicted? A comparison of the performance of macro-micro models with historical data for Brazil

What was the impact of Brazil's 1998-99 currency crisis-which resulted in a change of exchange rate regime and a large real devaluation-on the occupational structure of the labor force and the distribution of incomes? Would it have been possible to predict such effects ahead of the crisis? The authors present an integrated macro-micro model of the Brazilian economy in 1998. The model consists of an applied general equilibrium macroeconometric component, connected through a set of linkage aggregate variables to a microeconomic model of household incomes. The authors use this framework to predict the employment and distributional consequences of the 1999 Brazilian currency crisis, based on 1998 household survey data. They then test the predictive performance of the model by comparing its simulated results with the actual household survey data observed in 1999. In addition to the fully integrated macro-micro model, the authors also test the performances of the microeconometric model on its own, and of a"representative household groups"approach. They find that the integrated macro-micro econometric model, while still inaccurate on many dimensions, can actually predict the broad pattern of the incidence of changes in household incomes across the distribution reasonably well, and much better than the alternative approaches. The authors conclude that further experimentation with these tools might be of considerable potential usefulness to policymakers.Labor Policies,Payment Systems&Infrastructure,Economic Theory&Research,Banks&Banking Reform,Environmental Economics&Policies,Economic Theory&Research,Environmental Economics&Policies,Macroeconomic Management,Inequality,Economic Stabilization

Development of Prometeu autonomous robot for ball handling in Eurobot

Eurobot is a robotics European challenge for the young generation (university and technical schools) which is held annually, with a different challenge in every edition, and participate around about 200 teams every year. Each game comprises two teams competing against each other and does not allow draws. This work describes the design, development and building up of an autonomous mobile robot to fulfill this challenge. This paper includes the challenge description, robot design, sensors used, the strategy used and some conclusion. The team that built this robot and participated on Eurobot is made up of 4 industrial electronic undergraduate students from University of Minho

A biodiversidade

"[…]. O estudo da diversidade biológica – ou biodiversidade – e da ecologia está intimamente relacionado com a promoção da conservação da natureza. O termo "biodiversidade" nasceu no forum "BioDiversity" em Washington, em 1986, e foi pela primeira vez publicado em 1988 pela National Academy Press (Wilson, 1988 a, b). Rapidamente, o conceito tornou-se popular e segundo Wilson (1992) pode ser definido como: "... a variedade de organismos considerados a todos os níveis, desde a genética às espécies e aos ecossistemas1" (ver igualmente Reaka-Kudla et al., 1996). Esta definição incorpora três escalas de diversidade (genes, espécies, ecossistemas) que são actualmente consideradas como interdependentes, embora continuem a ser estudadas empiricamente em separado. Uma visão diferente do que consiste a biodiversidade foi recentemente apresentada por Hubbell (2001) que considera que este termo é sinónimo de "... riqueza em espécies e abundância relativa de espécies no espaço e no tempo2". Por outro lado, o conceito de diversidade funcional implica que as comunidades mais diversas não sejam necessariamente aquelas que possuem mais espécies, mas sim as que possuem maior número de grupos funcionais (isto é, guildes3) (Hector, 1998; Gaston e Spicer, 2004). Por exemplo, embora não sejam particularmente ricas em espécies, as florestas naturais dos Açores funcionam de forma eficaz, já que possuem o número de espécies suficiente nos vários grupos funcionais realizando funções únicas. […].