Field sources in a Lorentz symmetry breaking scenario with a single background vector

This paper is devoted to investigating the interactions between stationary sources of the electromagnetic field, in a model which exhibits explicit Lorentz-symmetry breaking due to the presence of a single background vector. We focus on physical phenomena that emerge from this kind of breaking and which have no counterpart in Maxwell Electrodynamics

Alterations in brain connectivity due to plasticity and synaptic delay

Brain plasticity refers to brain's ability to change neuronal connections, as a result of environmental stimuli, new experiences, or damage. In this work, we study the effects of the synaptic delay on both the coupling strengths and synchronisation in a neuronal network with synaptic plasticity. We build a network of Hodgkin-Huxley neurons, where the plasticity is given by the Hebbian rules. We verify that without time delay the excitatory synapses became stronger from the high frequency to low frequency neurons and the inhibitory synapses increases in the opposite way, when the delay is increased the network presents a non-trivial topology. Regarding the synchronisation, only for small values of the synaptic delay this phenomenon is observed

Recomendação de boro para o maracujazeiro amarelo em solo de Tabuleiro Costeiro.

Nos estados que mais produzem maracujá no Brasil: Bahia, Sergipe, Espírito Santo e Rio de Janeiro, o maracujazeiro é cultivado em solos de Tabuleiros Costeiros. No Estado da Bahia cultiva- se aproximadamente 45% da produção nacional (322.755 toneladas) em 23.227 hectares, cuja produtividade média é inferior à nacional. Em 6.845 hectares de solos de Tabuleiros Costeiros do Estado da Bahia são produzidos 76.355 toneladas de maracujá, o que representa 24% da produção do Estado e 29% da área cultivada (IBGE, 2009). Os solos de Tabuleiros Costeiros são altamente intemperizados, com baixos teores de matéria orgânica, baixa capacidade de armazenamento de água e altos teores de ferro e alumínio, favorecenda deficiência de boro nas plantas de maracujá (BORGES et al., 2010).bitstream/item/55052/1/ComunicadoTecnico-149.pdfPublicação eletrônica

Treatment of bimodality in proficiency test of pH in bioethanol matrix

The pH value in bioethanol is a quality control parameter related to its acidity and to the corrosiveness of vehicle engines when it is used as fuel. In order to verify the comparability and reliability of the measurement of pH in bioethanol matrix among some experienced chemical laboratories, reference material (RM) of bioethanol developed by Inmetro - the Brazilian National Metrology Institute - was used in a proficiency testing (PT) scheme. There was a difference of more than one unit in the value of the pH measured due to the type of internal filling electrolytic solutions (potassium chloride, KCl or lithium chloride, LiCl) from the commercial pH combination electrodes used by the participant laboratories. Therefore, bimodal distribution has occurred from the data of this PT scheme. This work aims to present the possibilities that a PT scheme provider can use to overcome the bimodality problem. Data from the PT of pH in bioethanol were treated by two different statistical approaches: kernel density model and the mixture of distributions. Application of these statistical treatments improved the initial diagnoses of PT provider, by solving bimodality problem and contributing for a better performance evaluation in measuring pH of bioethanol.Comment: 20 pages, 6 figures, Accepted for publication in Accreditation and Quality Assurance (ACQUAL

Produção de composto orgânico em pequenas propriedades.

Composto orgânico é um adubo natural, preparado com produtos de origem vegetal e animal, que contém nutrientes para as plantas, em diferentes quantidades. É formado por matéria orgânica, que é um fator de grande importância para tornar a terra mais adequada para o desenvolvimento das plantas.bitstream/item/106266/1/Produto-Foco-organico-3.pdfOnline