Numerical solution of linear models in economics: The SP-DG model revisited

In general, complex and large dimensional models are needed to solve real economic problems. Due to these characteristics, there is either no analytical solution for them or they are not attainable. As a result, solutions can be only obtained through numerical methods. Thus, the growing importance of computers in Economics is not surprising. This paper focuses on an implementation of the SP-DG model, using Matlab,developed by the students as part of the Computational Economics course. We also discuss some of our teaching/learning experience within the course, given for the first time in the FEP Doctoral Programme in Economics.SP-DG Model, Output, Inflation, Numerical Simulation, Teaching of Economics

Constraining planet structure and composition from stellar chemistry: trends in different stellar populations

The chemical composition of stars that have orbiting planets provides important clues about the frequency, architecture, and composition of exoplanet systems. We explore the possibility that stars from different galactic populations that have different intrinsic abundance ratios may produce planets with a different overall composition. We compiled abundances for Fe, O, C, Mg, and Si in a large sample of solar neighbourhood stars that belong to different galactic populations. We then used a simple stoichiometric model to predict the expected iron-to-silicate mass fraction and water mass fraction of the planet building blocks, as well as the summed mass percentage of all heavy elements in the disc. Assuming that overall the chemical composition of the planet building blocks will be reflected in the composition of the formed planets, we show that according to our model, discs around stars from different galactic populations, as well as around stars from different regions in the Galaxy, are expected to form rocky planets with significantly different iron-to-silicate mass fractions. The available water mass fraction also changes significantly from one galactic population to another. The results may be used to set constraints for models of planet formation and chemical composition. Furthermore, the results may have impact on our understanding of the frequency of planets in the Galaxy, as well as on the existence of conditions for habitability.Comment: Accepted for publication in Astronomy & Astrophysic

Abundance trend with condensation temperature for stars with different Galactic birth places

During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as Tc trend). However, the real astrophysical nature of this correlation is still debated. The main goal of this work is to explore the possible dependence of the Tc trend on stellar Galactocentric distances, Rmean. We used high-quality spectra of about 40 stars observed with the HARPS and UVES spectrographs to derive precise stellar parameters, chemical abundances, and stellar ages. A differential line-by-line analysis was applied to achieve the highest possible precision in the chemical abundances. We confirm previous results that [X/Fe] abundance ratios depend on stellar age and that for a given age, some elements also show a dependence on Rmean. When using the whole sample of stars, we observe a weak hint that the Tc trend depends on Rmean. The observed dependence is very complex and disappears when only stars with similar ages are considered. To conclude on the possible dependence of the Tc trend on the formation place of stars, a larger sample of stars with very similar atmospheric parameters and stellar ages observed at different Galactocentric distances is neededComment: Accepted by A&

Efeitos da substituíção da gordura do leite por gordura de soja no crescimento de bezerros.

A gordura hidrogenada de soja possibilitou um desenvolvimento corporal dos bezerros semelhantes ao conseguido atraves da gordura do leite

Espécies arbóreas nativas para composição de sistemas silvipastoris agroecológicos.

O presente trabalho teve por objetivo a análise do desenvolvimento de espécies arbóreas cultivadas em um sistema silvipastoril agroecológico desenvolvido para a produção leiteira em propriedades familiares. A pesquisa foi conduzida no CPRA ? Centro Paranaense de Referencia em Agroecologia, com base no histórico de dados de medidas de altura e DAP de 18 espécies arbóreas. A partir da análise dos dados foi estimado o crescimento anual de cada espécie identificando-se as que apresentam maior desenvolvimento e rentabilidade econômica. Também foram relacionados alguns serviços ambientais relacionados ao plantio das árvores em áreas de pastagem

Host adaptation to viruses relies on few genes with different cross-resistance properties

The deposited article is a post-print version and has peer review. This deposit is composed by the main article, and it hasn't any supplementary materials associated. The supplementary materials of the publication are only present in the editor's page of this article. This publication hasn't any creative commons license associated.Host adaptation to one parasite may affect its response to others. However, the genetics of these direct and correlated responses remains poorly studied. The overlap between these responses is instrumental for the understanding of host evolution in multiparasite environments. We determined the genetic and phenotypic changes underlying adaptation of Drosophila melanogaster to Drosophila C virus (DCV). Within 20 generations, flies selected with DCV showed increased survival after DCV infection, but also after cricket paralysis virus (CrPV) and flock house virus (FHV) infection. Whole-genome sequencing identified two regions of significant differentiation among treatments, from which candidate genes were functionally tested with RNAi. Three genes were validated--pastrel, a known DCV-response gene, and two other loci, Ubc-E2H and CG8492. Knockdown of Ubc-E2H and pastrel also led to increased sensitivity to CrPV, whereas knockdown of CG8492 increased susceptibility to FHV infection. Therefore, Drosophila adaptation to DCV relies on few major genes, each with different cross-resistance properties, conferring host resistance to several parasites.Fundação para a Ciência e a Tecnologia grants: (SFRH/BPD/62964/2009, SFRH/BD/82299/2011, PTDC/SAU-IMU/120673/2010); Austrian Science Fund grants: (P22725, P19467); European Research Council grant: (ArchAdapt); Instituto Gulbenkian de Ciência/Fundação Calouste Gulbenkian; Vetmeduni.info:eu-repo/semantics/publishedVersio

Transformação genética de feijão com construção gênica contendo o gene AtDREB2A visando tolerância à seca.

A Embrapa Arroz e Feijão busca avaliar o potencial desse fator de transcrição em feijão, no sentido de ativar a cadeia de genes necessários para obter tolerância ao estresse de deficiencia hídrica

Resistência fisiológica ao mofo branco usando o ácido oxálico em plantas transformadas do feijoeiro.

O presente trabalho teve como objetivo avaliar se há associação entre a resistência ao ácido oxálico em laboratório e a resistência em casa de vegetação quando efetuada inoculação com disco de meio de cultura contendo micélio do fungo