DSpace Coleção:
http://www.repositorio.ufc.br/handle/riufc/170
2019-11-20T21:00:10ZFermi-energy-dependent structural deformation of chiral single-wall carbon nanotubes
http://www.repositorio.ufc.br/handle/riufc/44386
Título: Fermi-energy-dependent structural deformation of chiral single-wall carbon nanotubes
Autor(es): Vieira, Bruno Gondim de Melo; Barros, Eduardo Bedê; Verçosa, Daniel Gomes; Samsonidze, Georgy; Souza Filho, Antonio Gomes de; Dresselhaus, Mildred Spiewak2014-01-01T00:00:00ZOptimal transport exponent in spatially embedded networks
http://www.repositorio.ufc.br/handle/riufc/44373
Título: Optimal transport exponent in spatially embedded networks
Autor(es): Reis, Saulo Davi Soares e; Moreira, André Auto; Havlin, Shlomo; Stanley, Harry Eugene; Andrade Júnior, José Soares de
Abstract: The imposition of a cost constraint for constructing the optimal navigation structure surely represents a crucial
ingredient in the design and development of any realistic navigation network. Previous works have focused on
optimal transport in small-world networks built from two-dimensional lattices by adding long-range connections
with Manhattan length rij taken from the distribution Pij ∼ r −α ij , where α is a variable exponent. It has been
shown that, by introducing a cost constraint on the total length of the additional links, regardless of the strategy
used by the traveler (independent of whether it is based on local or global knowledge of the network structure), the best transportation condition is obtained with an exponent α = d + 1, where d is the dimension of the underlying lattice. Here we present further support, through a high-performance real-time algorithm, on the validity of this conjecture in three-dimensional regular as well as in two-dimensional critical percolation clusters. Our results clearly indicate that cost constraint in the navigation problem provides a proper theoretical framework to justify the evolving topologies of real complex network structures, as recently demonstrated for the networks of the US airports and the human brain activity.2013-01-01T00:00:00ZSingle-file and normal diffusion of magnetic colloids in modulated channels
http://www.repositorio.ufc.br/handle/riufc/44275
Título: Single-file and normal diffusion of magnetic colloids in modulated channels
Autor(es): Camarão, Diego de Lucena; Galván Moya, Jesus Eduardo; Ferreira, Wandemberg Paiva; Peeters, Francois Maria Leopold
Abstract: Diffusive properties of interacting magnetic dipoles confined in a parabolic narrow channel and in the presence
of a periodic modulated (corrugated) potential along the unconfined direction are studied using Brownian
dynamics simulations. We compare our simulation results with the analytical result for the effective diffusion
coefficient of a single particle by Festa and d’Agliano [Physica A 90, 229 (1978)] and show the importance of
interparticle interaction on the diffusion process. We present results for the diffusion of magnetic dipoles as a
function of linear density, strength of the periodic modulation and commensurability factor.2014-01-01T00:00:00ZFuzzy spaces topology change and BH thermodynamics
http://www.repositorio.ufc.br/handle/riufc/44237
Título: Fuzzy spaces topology change and BH thermodynamics
Autor(es): Silva, Carlos Alex Souza da; Carvalho, Ricardo Renan Landim de
Abstract: What is the ultimate fate of something that falls into a black hole? From this question arises one of the most intricate problems of modern theoretical physics: the black hole information loss paradox. Bekenstein and Hawking have been shown that the entropy in a black hole is proportional to the surface area of its event horizon, which should be quantized in a multiple of the Planck area. This led G.’t Hooft and L. Susskind to propose the holographic principle which states that all the information inside the black hole can be stored on its event horizon. From this results, one may think if the solution to the information paradox could lies
in the quantum properties of the black hole horizon. One way to quantize the event horizon is to see it as a fuzzy sphere, which posses a closed relation with Hopf algebras. This relation makes possible a topology change process where a fuzzy sphere splits in two others. In this work it will be shown that, if one quantize the black hole event horizon as a fuzzy sphere taking into account its quantum symmetry properties, a topology change process to black holes can be defined without break unitarity or locality, and we can obtain a possible solution to the information paradox. Moreover, we show that this model can explain the origin of the black
hole entropy, and why black holes obey a generalized second law of thermodynamics.2014-01-01T00:00:00Z