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Search Results: 1 - 10 of 67333 matches for " Edilberto Costa;Silva "
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On planar quantum dynamics of a magnetic dipole moment in the presence of electric and magnetic fields
Edilberto O. Silva
Physics , 2014, DOI: 10.1140/epjc/s10052-014-3112-z
Abstract: The planar quantum dynamics of a neutral particle with a magnetic dipole moment in the presence of electric and magnetic fields is considered. The criteria to establish the planar dynamics reveal that the resulting nonrelativistic Hamiltonian has a simplified expression without making approximations, and some terms have crucial importance for system dynamics.
2DEG on a cylindrical shell with a screw dislocation
Cleverson Filgueiras,Edilberto O. Silva
Physics , 2015, DOI: 10.1016/j.physleta.2015.06.035
Abstract: A two dimensional electron gas on a cylindrical surface with a screw dislocation is considered. More precisely, we investigate how both the geometry and the deformed potential due to a lattice distortion affect the Landau levels of such system. The case showing the deformed potential can be thought in the context of 3D common semiconductors where the electrons are confined on a cylindrical shell. We will show that important quantitative differences exist due to this lattice distortion. For instance, the effective cyclotron frequency is diminished by the deformed potential, which in turn enhances the Hall conductivity.
Goldbach conjecture sequences in quantum mechanics
Thiago Prudencio,Edilberto O. Silva
Physics , 2013,
Abstract: We show that there is a correspondence between Goldbach conjecture sequences (GCS) and expectation values of the number operator in Fock states. We demonstrate that depending on the normalization or not of Fock state superpositions, we have sequences that are equivalent and sequences that are not equivalent to GCS. We propose an algorithm where sequences equivalent to GCS can be derived in terms of expectation values with normalized states. Defining states whose projections generate GCS, we relate this problem to eigenstates of quantum harmonic oscillator and discuss Fock states directly associated to GCS, taking into account the hamiltonian spectrum and quantum vacuum fluctuations. Finally, we address the problems of degeneracy, maps associating GCS and Goldbach partitions.
Prevalência de infec??o por Leishmania chagasi utilizando os métodos de ELISA (rK39 e CRUDE) e intradermorrea??o de Montenegro em área endêmica do Maranh?o, Brasil
Nascimento, Maria do Desterro Soares Brand?o;Souza, Edilberto Costa;Silva, Leopoldo Muniz da;Leal, Plinio da Cunha;Cantanhede, Karleno de Lima;Bezerra, Geusa Felipa de Barros;Viana, Gra?a Maria de Castro;
Cadernos de Saúde Pública , 2005, DOI: 10.1590/S0102-311X2005000600028
Abstract: a prospective study was undertaken in 1,520 children less than 15 years of age in s?o josé de ribamar, maranh?o, brazil, from june 1994 to january 1995, to evaluate the prevalence and characteristics (socioeconomic, environmental, and behavioral) associated with infection by leishmania chagasi. montenegro skin test (mst) and enzyme-linked immunosorbent assay (elisa-rk39 and crude) test were used to detect infection. the statistical analysis used the c2 test with yates correction and a p value less than 0.05 was considered statistically significant. prevalence of infection was 61.7% as measured by mst, 19.4% according to elisa (rk39), and 19.7% by elisa (crude). association was detected between leishmaniasis in the family, water supply, application of insecticide, and infection by l. chagasi using mst. no association with infection by l. chagasi was detected using elisa rk39 or crude. more effective control measures are needed to reduce prevalence and to detect asymptomatic cases in this high percentage of infected children.
Division of Labor in Pachycondyla striata Fr. Smith, 1858 (Hymenoptera: Formicidae: Ponerinae)
Adolfo da Silva-Melo,Edilberto Giannotti
Psyche , 2012, DOI: 10.1155/2012/153862
Abstract: Four colonies of the ant Pachycondyla striata were used to analyze the specie behavioral repertoire. Forty-six behavioral acts were recorded in laboratory. Here, we present the record the division of labor between the castes and the temporal polyethism of monomorphic workers. The queens carried out many of the behavioral traits recorded in this work however; they performed them less frequently compared to the worker. The workers activity involved chasing and feeding on fresh insects and usingthem to nourish larvae besides laying eggs in the C-posture, an activity also performed by queens, which is similar to that of wasps of the subfamily Stenogastrinae. The young workers were involved in activities of brood care, sexuate care, and nest maintenance, and the older workers were involved in defense, exploration, and foraging.
Effects of spin on the dynamics of the 2D Dirac oscillator in the magnetic cosmic string background
Fabiano M. Andrade,Edilberto O. Silva
Physics , 2014, DOI: 10.1140/epjc/s10052-014-3187-6
Abstract: In this work the dynamics of a 2D Dirac oscillator in the spacetime of a magnetic cosmic string is considered. It is shown that earlier approaches to this problem have neglected a $\delta$ function contribution to the full Hamiltonian, which comes from the Zeeman interaction. The inclusion of spin effects leads to results which confirm a modified dynamics. Based on the self-adjoint extension method, we determined the most relevant physical quantities, such as energy spectrum, wave functions and the self-adjoint extension parameter by applying boundary conditions allowed by the system.
Remarks on the Dirac oscillator in $(2+1)$ dimensions
Fabiano M. Andrade,Edilberto O. Silva
Physics , 2014, DOI: 10.1209/0295-5075/108/30003
Abstract: In this work the Dirac oscillator in $(2+1)$ dimensions is considered. We solve the problem in polar coordinates and discuss the dependence of the energy spectrum on the spin parameter $s$ and angular momentum quantum number $m$. Contrary to earlier attempts, we show that the degeneracy of the energy spectrum can occur for all possible values of $sm$. In an additional analysis, we also show that an isolated bound state solution, excluded from Sturm-Liouville problem, exists.
The 2D $κ$-Dirac oscillator
Fabiano M. Andrade,Edilberto O. Silva
Physics , 2014, DOI: 10.1016/j.physletb.2014.09.017
Abstract: In this Letter, 2D Dirac oscillator in the quantum deformed framework generated by the $\kappa$-Poincar\'{e}-Hopf algebra is considered. The problem is formulated using the $\kappa$-deformed Dirac equation. The resulting theory reveals that the energies and wave functions of the oscillator are modified by the deformation parameter.
Aharonov--Bohm problem for vector bosons
Luis B. Castro,Edilberto O. Silva
Physics , 2015,
Abstract: The Aharonov--Bohm (AB) problem for vector bosons by the Duffin--Kemmer--Petiau (DKP) formalism is analyzed. The relevant eigenvalue equation coming from the DKP formalism reveals an equivalence to the spin--$1/2$ AB problem. By using the self--adjoint extension approach, we examine the bound state scenario. The energy spectra are explicitly computed as well as their dependencies on the magnetic flux parameter and also the conditions for the occurrence of bound states.
Cytotoxic lipidic α-amino acids from the zoanthid Protopalythoa variabilis from the Northeastern coast of Brazil
Wilke, Diego Veras;Jimenez, Paula Christine;Pessoa, Claudia;Moraes, Manoel Odorico de;Araújo, Renata Mendon?a;Silva, Wildson Max Barbosa da;Silveira, Edilberto Rocha;Pessoa, Otília Deusdênia Loiola;Braz-Filho, Raimundo;Lopes, Norberto Peporine;Costa-Lotufo, Letícia Veras;
Journal of the Brazilian Chemical Society , 2009, DOI: 10.1590/S0103-50532009000800010
Abstract: two lipidic α-amino acids 1a and 1b were isolated from the zoanthid protopalythoa variabilis using a bioguided fractionation for cytotoxic activity. the structures of the metabolites were determined by spectroscopic methods, including nmr (nuclear magnetic resonance) 1h e 13c, ir (infrared) and high resolution mass spectrometry (positive mode). the cytotoxic activity of the crude extract, as well as of the mixture of 1a and 1b were measured in vitro using the mtt assay for four human tumor cell lines. this finding has important biological and chemical implications for this type of compound. this is the first report of lipidic α-amino acids from natural sources, as well as of their cytotoxic activity.
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