Nondispersive analytical solutions to the Dirac equation

This paper presents new analytic solutions to the Dirac equation employing a recently introduced method that is based on the formulation of spinorial fields and their driving electromagnetic fields in terms of geometric algebras. A first family of solutions describe the shape-preserving translation of a wavepacket along any desired trajectory in the x-y plane. In particular, we show that the dispersionless motion of a Gaussian wavepacket along both elliptical and circular paths can be achieved with rather simple electromagnetic field configurations. A second family of solutions involves a plane electromagnetic wave and a combination of generally inhomogeneous electric and magnetic fields. The novel analytical solutions of the Dirac equation given here provide important insights into the connection between the quantum relativistic dynamics of electrons and the underlying geometry of the Lorentz group

Integração Lavoura-Pecuária-Floresta: produção de alimentos, agroenergia e madeira.

bitstream/item/26964/1/Ramon-1.pd

Integração Lavoura-Pecuária-Floresta.

bitstream/item/35650/1/Integracao-lavoura.pd

Surface recombination measurements on III–V candidate materials for nanostructure light-emitting diodes

Surface recombination is an important characteristic of an optoelectronic material. Although surface recombination is a limiting factor for very small devices it has not been studied intensively. We have investigated surface recombination velocity on the exposed surfaces of the AlGaN, InGaAs, and InGaAlP material systems by using absolute photoluminescence quantum efficiency measurements. Two of these three material systems have low enough surface recombination velocity to be usable in nanoscale photonic crystal light-emitting diodes

Early Detection Of Metabolic And Energy Disorders By Thermal Time Series Stochastic Complexity Analysis.

Maintenance of thermal homeostasis in rats fed a high-fat diet (HFD) is associated with changes in their thermal balance. The thermodynamic relationship between heat dissipation and energy storage is altered by the ingestion of high-energy diet content. Observation of thermal registers of core temperature behavior, in humans and rodents, permits identification of some characteristics of time series, such as autoreference and stationarity that fit adequately to a stochastic analysis. To identify this change, we used, for the first time, a stochastic autoregressive model, the concepts of which match those associated with physiological systems involved and applied in male HFD rats compared with their appropriate standard food intake age-matched male controls (n=7 per group). By analyzing a recorded temperature time series, we were able to identify when thermal homeostasis would be affected by a new diet. The autoregressive time series model (AR model) was used to predict the occurrence of thermal homeostasis, and this model proved to be very effective in distinguishing such a physiological disorder. Thus, we infer from the results of our study that maximum entropy distribution as a means for stochastic characterization of temperature time series registers may be established as an important and early tool to aid in the diagnosis and prevention of metabolic diseases due to their ability to detect small variations in thermal profile.4770-

FUEL CELL: FEASIBILITY ANALYSIS OF ITS APPLICATION IN AUTOMOBILES

The need to reduce the emission of harmful gases into human life, together with the dependence on oil as a primary source of fuel for internal combustion engines (ICE), are part of the current global scenario. This scenario opens space for fuel cells (FC), technology that generates electricity as the main product of oxide-reduction reactions between Hydrogen and Oxygen. An efficient and clean alternative that appears as a possibility for the substitution of ICE. The present article proposes a model of FC and compares it technically with a conventional ICE, in order to prove the efficiency, performance and environmental impact feasibility of the use of this technology in commercial vehicles

Uso de imagens na avaliação da cobertura do solo sob diferentes manejos.

Este experimento teve por objetivo avaliar a influência dos sistemas de integração lavoura-pecuária e pastagem contínua, através da análise de imagens processadas pelo programa QUANTIPORO, em relação à cobertura vegetal do solo. O estudo foi realizado na área experimental da Embrapa Milho e Sorgo, Sete Lagoas, MG. Os sete tratamentos avaliados foram constituídos por três sistemas de produção com rotação de culturas de soja e milho grão e pastagem contínua. As imagens foram efetuadas uma vez por ano em cada tratamento, nas três repetições, no período pós-colheita das culturas. O delineamento das parcelas era o de blocos ao acaso, com três repetições. As fotos foram retiradas utilizando-se máquina fotográfica digital e as imagens foram analisadas através do software QUANTIPORO. A influência dos tipos de manejo em relação à cobertura vegetal do solo, foi constatada