University Federal da Paraba
University Federal da Paraba
Romero C.,University Federal da Paraba
AIP Conference Proceedings | Year: 2015
Weyl's attempt to unify electromagnetism and gravity set the stage for a number of developments in theoretical physics and geometry. We review the essential ideas of Weyl's theory and Einstein's reaction at the time. We revisit some aspects of Weyl geometry and discuss the role they could still play to approach some problems of contemporary cosmological research. © 2015 AIP Publishing LLC.
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.
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.
PubMed | Otto Von Guericke University of Magdeburg and University Federal da Paraba
Type: Journal Article | Journal: The journal of physical chemistry letters | Year: 2015
We report numerical evidence of a new type of wide-ranging organization of mixed-mode oscillations (MMOs) in a model of the peroxidase-oxidase reaction, in the control parameter plane defined by the supply of the reactant NADH and the pH of the medium. In classic MMOs, the intervals of distinct periodic oscillations are always separated from each other by windows of chaos. In contrast, in the new unfolding, such windows of chaos do not exist. Chaos-mediated and nonchaos-mediated MMO phases are separated by a continuous transition boundary in the control parameter plane. In addition, for low pH values, we find an exceptionally wide and intricate mosaic of MMO phases that is described by a detailed phase diagram.
Maia M.D.,University of Brasilia |
Monte E.M.,University Federal da Paraba
Journal of Physics: Conference Series | Year: 2011
The eventual production of mini black holes by proton-proton collisions at the LHC is predicted by theories with large extra dimensions resolvable at the Tev scale of energies. It is expected that these black holes evaporate shortly after its production as a consequence of the Hawking radiation. We show that for theories based on the ADS/CFT correspondence, the produced black holes may have an unstable horizon, which grows proportionally to the square of the distance to the collision point. © Published under licence by IOP Publishing Ltd.
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.
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).
Cardoso W.B.,Federal University of Goais |
Avelar A.T.,Federal University of Goais |
Bazeia D.,University Federal da Paraba
Nonlinear Analysis: Real World Applications | Year: 2010
This work deals with soliton solutions of the nonlinear Schrdinger equation with a diversity of nonlinearities. We solve the equation in a potential which oscillates in time between attractive and expulsive behavior, in the presence of nonlinearities which are modulated in space and time. Despite the presence of the periodically expulsive behavior of the potential, the results show that the nonlinear equation can support a diversity of localized excitations of the bright and dark types. © 2009 Elsevier Ltd. All rights reserved.
Pedrosa I.A.,University Federal da Paraba |
De Lima D.A.P.,University Federal da Paraba
International Journal of Modern Physics B | Year: 2014
In this paper, we study the generalized harmonic oscillator with arbitrary timedependent mass and frequency subjected to a linear velocity-dependent frictional force from classical and quantum points of view. We obtain the solution of the classical equation of motion of this system for some particular cases and derive an equation of motion that describes three different systems. Furthermore, with the help of the quantum invariant method and using quadratic invariants we solve analytically and exactly the time-dependent Schrödinger equation for this system. Afterwards, we construct coherent states for the quantized system and employ them to investigate some of the system's quantum properties such as quantum fluctuations of the coordinate and the momentum as well as the corresponding uncertainty product. In addition, we derive the geometric, dynamical and Berry phases for this nonstationary system. Finally, we evaluate the dynamical and Berry phases for three special cases and surprisingly find identical expressions for the dynamical phase and the same formulae for the Berry's phase. © World Scientific Publishing Company.
Vitoria R.L.L.,University Federal da Paraba |
Bakke K.,University Federal da Paraba
European Physical Journal Plus | Year: 2016
The behaviour of the Klein-Gordon oscillator under the influence of linear and Coulomb-type potentials is investigated. The introduction of the scalar potentials is made by modifying the mass term of the Klein-Gordon equation, then, by searching for relativistic bound states, a particular quantum effect can be observed: a dependence of the angular frequency of the Klein-Gordon oscillator on the quantum numbers associated with the radial modes and the angular momentum. As an example, we analyse the angular frequency and the energy level associated with the ground state of the relativistic system. © 2016, Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg.