Entanglement versus Quantum Discord in Two Coupled Double Quantum Dots

We study the dynamics of quantum correlations of two coupled double quantum dots containing two excess electrons. The dissipation is included through the contact with an oscillator bath. We solve the Redfield master equation in order to determine the dynamics of the quantum discord and the entanglement of formation. Based on our results, we find that the quantum discord is more resistant to dissipation than the entanglement of formation for such a system. We observe that this characteristic is related to whether the oscillator bath is common to both qubits or not and to the form of the interaction Hamiltonian. Moreover, our results show that the quantum discord might be finite even for higher temperatures in the asymptotic limit.Comment: 14 pages, 8 figures (new version is the final version to appear in NJP

Sistema físico de produção de leite da UEPAE Porto Velho: análise dos resultados zootécnicos e econômicos referentes ao período de dezembro/84 a setembro/89.

No campo experimental da Unidade de Execução de Pesquisa de Âmbito Estadual de Porto Velho (UEPAE de Porto Velho), da EMBRAPA, em Porto Velho, RO, vem sendo conduzido, desde 1984, um modelo físico de sistema de produção de leite. Este modelo tem por objetivo precípuo viabilizar a atividade leiteira na região, elevando sua produtividade e rentabilidade através da utilização de técnicas integradas de modo que se tomem instrumento de difusão de tecnologia. Atualmente, a produtividade leiteira do rebanho na região é muito baixa, situando-se em tomo de 540 l de leite/vaca/lactação de 180 dias. A partir de um rebanho mestiço Holando x Zebu, com graus de sangue 112,9/16 e 5/8, pretende-se alcançar índices econômicos de produtividade, através de tecnologias que possam ser adotadas pelos produtores locais. Dentre as tecnologias utilizadas destacam-se: inseminação artificial, pastagens diversificadas, pastejo rotacionado, suplementação dos animais com volumosos e concentrados regionais, banco de proteína e desmama precoce. Até o presente, os resultados alcançados vêm superando as metas préestabelecidas, confirmando, desse modo, a eficiência das técnicas aplicadas no sistema.bitstream/item/54885/1/SP210001.pd

Modeling and simulation of wetted porous thermal barriers operating under high temperature or high heat flux

Porous media with high water content can be successfully used as thermal barriers to operate under high exposure temperatures and/or high heat fluxes. Modeling and simulation of such systems presents difficulties and challenges, which are pointed and worked out in this work. Liquid water and water vapor transfers are considered, including the capillary effects for the liquid phase, as well as the air transfer inside the porous medium. Heat transfer model includes conduction, radiation, enthalpy convection, sensible heating and phase change. A realistic model is considered at the exposed boundary in what concerns mass transfer: the outflow mass transfer is dictated by the water effusion and not by the convection transfer mechanism between the exposed surface and the environment. A set of numerical aspects is detailed, concerning both the numerical modeling and the solution of the discretization equations, which are crucial to obtain successful simulations. Some illustrative results are presented, showing the potential of the wetted porous media when used as thermal barriers, as well as the capabilities of the presented physical and numerical models to deal with such systems.http://www.sciencedirect.com/science/article/B6V3H-4RKDHVC-2/1/633ef2cefc7a7e2178f1d59743e3d24