Photon Fields
Mostrando 1-12 de 21 artigos, teses e dissertações.
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1. Electrochemical and Optical Investigation of Conductive Polymer and MWCNT Nanocomposite Film
Composites of multi-walled carbon nanotubes (MWCNT) and conductive polymer with good uniformity were prepared by electropolymerization. Molecular modeling calculations were carried out for electroactive monomer (OAP) polymerization with density functional theory (DFT) level using 6-311G(d,p) basis set for all atoms and Gaussian 03 program package. The reflec
J. Braz. Chem. Soc.. Publicado em: 2015-02
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2. Femtosecond lasers for processing glassy and polymeric materials
Novel materials have been developed to meet the increasing mechanical, electrical and optical properties required for technological applications in different fields of sciences. Among the methods available for modifying and improving materials properties, femtosecond laser processing is a potential approach. Owing to its precise ablation and modification cap
Mat. Res.. Publicado em: 27/09/2013
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3. Is it possible to accommodate massive photons in the framework of a gauge-invariant electrodynamics?
The construction of an alternative electromagnetic theory that preserves Lorentz and gauge symmetries, is considered. We start off by building up Maxwell electrodynamics in (3+1)D from the assumption that the associated Lagrangian is a gauge- invariant functional that depends on the electron and photon fields and their first derivatives only. In this scenari
Brazilian Journal of Physics. Publicado em: 2010-09
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4. Nonlinear optical properties of organic and organometallic compounds / Propriedades ópticas não lineares de compostos orgânicos e organometálicos
In the last few years, the design and characterization of novel materials exhibiting high optical nonlinearities is the subject of a fast-growing interest because of their potential application in various fields, from biology to photonics. Two-photon absorption processes, for example, have been used for optical limiting, three-dimensional microfabrication, o
Publicado em: 2009
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5. Perda de coerencia e teletransporte em eletrodinamica quantica de cavidades / Decoherence and teleportation in cavity quantum electrodynamics
In this work, we analyze concepts of Quantum Information and Quantum Optics in the context of Cavity Quantum Electrodynamics (CQED). Nowadays, CQED is achieving great technological advances, justifying the interest in several proposals of experimental implementation. In the first part of the work, we consider the effect of spontaneous emission in a system of
Publicado em: 2008
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6. Magnetically driven maser effect in the resonant dynamics of V15 molecular nanomagnets
Resonant dynamics of magnetic molecules with spin 1/2 ground state, such as V15, is theoretically studied. In our model calculation, crystals of this molecular nanomagnet are probed by time-dependent magnetic fields, which continuously invert populations of spin states. If the sample is placed in a resonant cavity, relaxation of excited states, via spin-phot
Brazilian Journal of Physics. Publicado em: 2007-09
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7. Implantação de um programa de controle de qualidade para sistemas de planejamento de tratamento computadorizados de acordo com o TRS 430 / Implementation of a quality assurance program for computerized treatment planning systems according to TRS 430
This work presents the guidelines and necessary tests tom implement a quality assurance program for Eclipse 7.3.10 from Varian at Hospital das Clinicas, Sao Paulo University School of Medicine - Brazil, in accordance with the new IAEA publication TRS 430. The recommended tests for the TRS 430 air mainly classified into acceptance tests, commissioning (dosime
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 27/04/2006
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8. UtilizaÃÃo de redes neurais artificiais para identificaÃÃo de energia em campos fotÃnicos com materiais termoluminescentes / Application of neural networks to the energy identification in photon fields with thermoluminescent material
A alta qualidade de um serviÃo de monitoraÃÃo individual à de fundamental importÃncia para a seguranÃa dos trabalhadores que exercem suas atividades em ambientes controlados e dependem de avaliaÃÃes precisas das doses que receberam e podem vir a receber durante o desempenho das suas atividades profissionais. O investimento em pesquisas que possibilit
Publicado em: 2006
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9. Individual monitoring for external exposures: experimentation and simulation with Monte Carlo Method / Monitoração individual externa: experimentos e simulações com o método de Monte Carlo
In this work, we have evaluated the possibility of applying the Monte Carlo simulation technique in photon dosimetry of external individual monitoring. The GEANT4 toolkit was employed to simulate experiments with radiation monitors containing TLD-100 and CaF2:NaCl thermoluminescent detectors. As a first step, X ray spectra were generated impinging electrons
Publicado em: 2005
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10. Espectroscopia Ãptica nÃo linear em sistemas atÃmicos envolvendo nÃveis de Rydberg
In this thesis we study nonlinear optical effects in alkali vapors, in which Rydberg levels play the role of near resonant intermediate levels, focusing our attention in processes such as: four wave mixing (FWM), two photon absorption, sum frequency generation (SF) and difference frequency generation (DF). We analyze a FWM process with two-photon transitions
Publicado em: 2002
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11. Dirac's æther in curved spacetime
Proca's equations for two types of fields in a Dirac's æther with electric conductivity sigma are solved exactly. The Proca electromagnetic fields are assumed with cylindrical symmetry. The background is a static, curved spacetime whose spatial section is homogeneous and has the topology of either the three-sphere S³ or the projective three-space P³. Simp
Anais da Academia Brasileira de Ciências. Publicado em: 2000-06
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12. Calculo da dose de radiação atraves de convoluções em meios heterogeneos para aplicações em radioterapia
In this thesis we have applied the convolution techniques to calculate the three dimensional (3D) dose distribution to be used in teletherapy. The convolution method spans the total dose in three parts: one due to the energy released by charged particles produced at the first collisions, one due to the energy released by the first scattered photons, and the
Publicado em: 2000