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João Pessoa, Brazil

Lozano G.,University of Buenos Aires | Mohammadi A.,University Federal da Paraba | Schaposnik F.A.,National University of La Plata
Journal of High Energy Physics | Year: 2015

In this paper we study a 2 + 1 dimensional system in which fermions are coupled to the self-dual topological vortex in U(1) × U(1) Chern-Simons theory, where both U(1) gauge symmetries are spontaneously broken. We consider two Abelian Higgs scalars with visible and hidden sectors coupled to a fermionic field through three interaction La-grangians, where one of them violates the fermion number. Using a fine tuning procedure, we could obtain the number of the fermionic zero modes which is equal to the absolute value of the sum of the vortex numbers in the visible and hidden sectors. © 2015, The Author(s).

Machado L.P.,Federal University of Para | Rosas A.,University Federal da Paraba | Lindenberg K.,University of California at San Diego
European Physical Journal E | Year: 2014

Abstract: We study via numerical simulations a granular chain not only with decreasing radii (forward tapering) in geometric progression, but also decorated with grains positioned on the top and bottom of the chain, without altering its original length. The decorating grains act as an auxiliary chain which traps part of the energy and linear momentum, both propagating as a pulse due to disturbances produced at the end of the chain. Thus, this configuration optimizes the impact attenuation and aligns the chain naturally (by symmetry) which facilitates the construction of the experimental setup. Furtheremore, since the decorating grain radii increase along the chain, this new type of chain is necessarily short in order to avoid precompression. Nevertheless, even with short chains, it is possible to mitigate impacts almost completely. © 2014, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Olmo G.J.,University of Valencia | Olmo G.J.,University Federal da Paraba | Rubiera-Garcia D.,Fudan University
International Journal of Modern Physics D | Year: 2015

Effective geometries arising from a hypothetical discrete structure of spacetime can play an important role in the understanding of the gravitational physics beyond General Relativity (GR). To discuss this question, we make use of lessons from crystalline systems within solid state physics, where the presence of defects in the discrete microstructure of the crystal determine the kind of effective geometry needed to properly describe the system in the macroscopic continuum limit. In this work, we study metric-affine theories with nonmetricity and torsion, which are the gravitational analog of crystalline structures with point defects and dislocations. We consider a crystal-motivated gravitational action and show the presence of topologically nontrivial structures (wormholes) supported by an electromagnetic field. Their existence has important implications for the quantum foam picture and the effective gravitational geometries. We discuss how the dialogue between solid state physics systems and modified gravitational theories can provide useful insights on both sides. © 2015 World Scientific Publishing Company.

Vasconcellos A.,Federal University of Rio Grande do Norte | Moura F.M.D.S.,University Federal da Paraba
Journal of Insect Science | Year: 2010

Termites constitute a considerable fraction of the animal biomass in tropical forest, but little quantitative data are available that indicates their importance in the processes of wood decomposition. This study evaluated the participation of Nasutitermes corniger (Motschulsky) (Isoptera: Termitidae), N. ephratae (Holmgren), and N. macrocephalus (Silvestri) in the consumption of the wood litter in a remnant area of Atlantic Coastal Forest in northeastern Brazil. The populations of this species were quantified in nests and in decomposing tree trunks, while the rate of wood consumption was determined in the laboratory using wood test-blocks of Clitoria fairchildiana Howard (Fabales: Fabaceae), Cecropia sp. (Urticales: Cecropiaceae), and Protium heptaphyllum (Aublet) Marchand (Sapindales: Burseraceae). The abundance of the three species of termites varied from 40.8 to 462.2 individuals/m2. The average dry wood consumption for the three species was 9.4 mg/g of termites (fresh weight)/day, with N. macrocephalus demonstrating the greatest consumption (12.1 mg/g of termite (fresh weight)/day). Wood consumption by the three species of Nasutitermes was estimated to be 66.9 kg of dry wood /ha/year, corresponding to approximately 2.9% of the annual production of wood-litter in the study area. This consumption, together with that of the other 18 exclusively wood-feeders termite species known to occur in the area, indicates the important participation of termites in removing wood-litter within the Atlantic Coastal Forest domain.

Junior A.D.D.C.,University of Sao Paulo | Batista L.V.,University Federal da Paraba
Proceedings - 2012 11th International Conference on Machine Learning and Applications, ICMLA 2012 | Year: 2012

The aim of this work is to propose four methods for composer classification in symbolic data based on melodies making use of the Prediction by Partial Matching (PPM) algorithm, and also to propose data modeling inspired on psycho physiological aspects. Rhythmic and melodic elements are combined instead of using only melody or rhythm alone. The models consider the perception of pitch changing and note durations articulations then the models are used to classify melodies. On the evaluation of our approach, we applied the PPM method on a small set of monophonic violin melodies of five composers in order to create models for each composer. The best accuracy achieved was of 86%, which is relevant for a problem domain that by now can be considered classic in MIR. © 2012 IEEE.

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