Espectros fractais em sistemas nanoestruturados e cristais fotônicos

The study of the elementary excitations such as photons, phonons, plasmons, polaritons, polarons, excitons and magnons, in crystalline solids and nanostructures systems are nowdays important active field for research works in solid state physics as well as in statistical physics. With this aim in mind, this work has two distinct parts. In the first one, we investigate the propagation of excitons polaritons in nanostructured periodic and quasiperiodic multilayers, from the description of the behavior for bulk and surface modes in their individual constituents. Through analytical, as well as computational numerical calculation, we obtain the spectra for both surface and bulk exciton-polaritons modes in the superstructures. Besides, we investigate also how the quasiperiodicity modifies the band structure related to the periodic case, stressing their amazing self-similar behavior leaving to their fractal/multifractal aspects. Afterwards, we present our results related to the so-called photonic crystals, the eletromagnetic analogue of the electronic crystalline structure. We consider periodic and quasiperiodic structures, in which one of their component presents a negative refractive index. This unusual optic characteristic is obtained when the electric permissivity and the magnetic permeability µ are both negatives for the same range of angular frequency ω of the incident wave. The given curves show how the transmission of the photon waves is modified, with a striking self-similar profile. Moreover, we analyze the modification of the usual Planck´s thermal spectrum when we use a quasiperiodic fotonic superlattice as a filter.

A relação urbano-rural no contexto da metrópole: um enfoque nos assentamentos rurais da RMN

The work however presented try to make an analysis of the relation urban-agricultural in the context of the process of metropolization of Natal. On the basis of this approach searched to argue the estruturation of the Brazilian urban space and the relation with the agricultural one, evidencing an academic debate little contemplated, in view of that the space transformations guided by Brazilian industrialization had earned as endorsement a mere urban direction, fact that neglected factors more complex than they for the urban-agricultural relation in the context of the urbanization and, more recently, of the metropolization. Another important factor in the construction of the work was the contextualization of the urbanization of the Rio Grande do Norte, as well as of the metropolization of Natal, where if the significant presence of an agricultural reality made an analysis of the configuration metropolitan in the present time displaying that also remains and reproduces the metropolis, fact that conditions and justifies the treatment of the reality metropolitan for the bias of the urban-agricultural relation. The approach of this relation was directed for the agricultural nestings of the Region Metropolitan of Natal (RMN), understood as fragments agricultural in the context of the metropolis, in view of that a tenuous correspondence of these nestings with the metropolis in the direction of its integration was observed. As methodology one used bibliographical survey in periodic and books and collected secondary data-collecting next to the IBGE and to the INCRA and still were directed a field research where interviews next to the seated ones had been carried through. In this direction, one evidenced that the metropolization also absorbs and even though it reproduces the ruralidade that if verifies in the RMN finishing for mining the idea of an urban one that it excludes the agricultural one. In the case of the RMN, we have agricultural and the urban one exactly if conforming in one space that is metropolitan

Perfil dos portadores de cavidade anoftálmica: estudo na Faculdade de Medicina de Botucatu - UNESP

OBJETIVO: Avaliar o perfil dos portadores de cavidade anoftálmica e a evolução dos pacientes com os tratamentos empregados. MÉTODOS: Estudo retrospectivo, realizado na Faculdade de Medicina de Botucatu, avaliando-se o perfil e a evolução dos portadores de cavidade anoftálmica, tratados no serviço. Os dados foram estudados segundo frequência de ocorrência e análise de associação. RESULTADOS: Os portadores de cavidade anoftálmica eram mais frequentemente em homens, trabalhadores em atividades exercidas com as mãos, jovens. O trauma e a phthisis bulbi foram as causas mais encontradas, havendo diferenças de acordo com a faixa etária e sexo. O índice complicações foi alto (57,1% dos casos), a maioria ocorrendo tardiamente. CONCLUSÕES: O trauma continua sendo causa importante de perda do olho. As complicações que ocorrem durante o acompanhamento do portador de cavidade anoftálmica são frequentes e ocorrem, em geral, tardiamente, o que reforça a necessidade de acompanhamento periódico e prolongado destes pacientes.

Tafonomia de tempestitos conchíferos amalgamados da formação Teresina em Rio Preto (Estado do Paraná, permiano médio, bacia do Paraná) e suas implicações paleoambientais

The deposits of the Permian Teresina Formation are mainly characterized by fi ne-grained siliciclastic rocks and centimetric intercalations of tempestites (bioclastic sandstones and coquinas). Despite the relevance of the bivalve-rich carbonate beds of the Teresina Formation to paleoenvironmental studies, their taphonomy is still poorly studied. The fossil concentration studied in this work was found in a quarry in the city of Irati, Rio Preto district, Parana State. The fossil concentration is located in the middle/upper portion of the unit, far from the top. The studied bed is a bioclastic, intraclastic, peloidal, grainstone/ packstone, with abundant bivalve shell fragments, pelitic and micritic intraclasts, peloids, rare ooids and oncoids, as well as permineralized of Lycophyta microphylles and fish scales. The grains of this carbonate concentration show: high degree of time-averaging, variable degree of packing (dense to disperse), no sorting and chaotic orientation. Notably, the concentration includes a mixture of elements which are indicative of: a) restrictive, low energy, carbonate environment (peloids, ooids and oncoids); b) subaerial environment surrounding the main body of water (Lycophyta microphylles) and c) quiet-water environment punctuated by storm events, where the suspension-feeding bivalves thrived. At least four depositional events caused by storm fl ows were recorded. The amalgamated nature of the bed is a result of storm events in an intracratonic basin with very low seafl oor slope and low rates of sedimentation and subsidence.

Estudos sobre estrutura, ciclo de vida e comportamento de Sardinella brasiliensis (Steindachner, 1879), na área entre 22ºs e 28ºs, Brasil: 1. morfologia dos otólitos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A note about the appearance of non-hyperbolic solutions in a mechanical pendulum system

The investigation of the behavior of a nonlinear system consists in the analysis of different stages of its motion, where the complexity varies with the proximity of a resonance region. Near this region the stability domain of the system undergoes sudden changes due basically to competition and interaction between periodic and saddle solutions inside the phase portrait, leading to the occurrence of the most different phenomena. Depending of the domain of the chosen control parameter, these events can reveal interesting geometric features of the system so that the phase portrait is not capable to express all them, since the projection of these solutions on the two-dimensional surface can hide some aspects of these events. In this work we will investigate the numerical solutions of a particular pendulum system close to a secondary resonance region, where we vary the control parameter in a restrict domain in order to draw a preliminary identification about what happens with this system. This domain includes the appearance of non-hyperbolic solutions where the basin of attraction in the center of the phase portrait diminishes considerably, almost disappearing, and afterwards its size increases with the direction of motion inverted. This phenomenon delimits a boundary between low and high frequency of the external excitation.

Impact dampers for controlling chaos in systems with limited power supply

We investigate numerically the dynamical behavior of a non-ideal mechanical system consisting of a vibrating cart containing a particle which can oscillate back and forth colliding with walls carved in the cart. This system represents an impact damper for controlling high-amplitude vibrations and chaotic motion. The motion of the cart is induced by an in-board non-ideal motor driving an unbalanced rotor. We study the phase space of the cart and the bouncing particle, in particular the intertwined smooth and fractal basin boundary structure. The control of the chaotic motion of the cart due to the particle impacts is also investigated. Our numerical results suggests that impact dampers of small masses are effective to suppress chaos, but they also increase the final-state sensitivity of the system in its phase space. (C) 2004 Elsevier Ltd. All rights reserved.

Small-angle X-ray scattering study of the smart thermo-optical behavior of zirconyl aqueous colloids

The smart thermo-optical systems studied here are based on the unusual thermoreversible sol-gel transition of zirconyl chloride aqueous solution modified by sulfuric acid in the molar ratio Zr/SO4:3/1. The transparency to the visible light changes during heating due to light scattering. This feature is related to the aggregates growth that occurs during gelation. These reversible changes can be controlled by the amount of chloride ions in solution. The thermoreversible sol-gel transition temperature increases from 323 to 343 K by decreasing the molar ratio Cl/Zr from 7.0 to 1.3. In this work the effect of the concentration of chloride ions on the structural characteristics of the system has been analyzed by in situ SAXS measurements during the sol-gel transition carried out at 323 and 333 K. The experimental SAXS curves of sols exhibit three regions at small, medium and high scattering vectors characteristics of Guinier, fractal and Porod regimes, respectively. The radius of primary particles, obtained from the crossover between the fractal and Porod regimes, remains almost invariable with the chloride concentration, and the value (4 Angstrom) is consistent with the size of the molecular precursor. During the sol-gel transition the aggregates grow with a fractal structure and the fractal dimensionality decreases from 2.4 to 1.8. This last value is characteristic of a cluster-cluster aggregation controlled by a diffusion process. Furthermore, the time exponent of aggregate growth presents values of 0.33 and 1, typical of diffusional and hydrodynamic motions. A crossover between these two regimes is observed.

On nonlinear dynamics in a free fluid surface of a tank excited by a non-ideal power source

We investigate the nonlinear oscillations in a free surface of a fluid in a cylinder tank excited by non-ideal power source, an electric motor with limited power supply. We study the possibility of parametric resonance in this system, showing that the excitation mechanism can generate chaotic response. Additionally, the dynamics of parametrically excited surface waves in the tank can reveal new characteristics of the system. The fluid-dynamic system is modeled in such way as to obtain a nonlinear differential equation system. Numerical experiments are carried out to find the regions of chaotic solutions. Simulation results are presented as phase-portrait diagrams characterizing the resonant vibrations of free fluid surface and the existence of several types of regular and chaotic attractors. We also describe the energy transfer in the interaction process between the hydrodynamic system and the electric motor. Copyright © 2011 by ASME.

Artificial satellites: Resonance effects produced by terrestrial tide

Effects due to resonances in the orbital motion of artificial satellites disturbed by the terrestrial tide are analyzed. The nodal co-rotation resonance, apsidal co-rotation resonance and the Lidov-Kozai's mechanism are studied. The effects of the resonances are analyzed through the variations of the metric orbital elements. Libration and circulation motions for high orbits with high eccentricities are verified for the Lidov-Kozai's mechanism.

Controle de dinâmica caótica com toros robustos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Eça de Queirós e a Gazeta de Notícias (suplemento literário -1892)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O ensino da literatura e a formação de professores em cursos de Letras

Pós-graduação em Letras - FCLAS

Caos e controle de microviga em balanço de um microscópio de força atômica, operando em modo intermitente, na ressonância

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Eficácia de gestão de unidades de conservação gerenciadas pelo Instituto Florestal de São Paulo, Brasil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)