Electronic Phase Separation Transition as the Origin of the Superconductivity and the Pseudogap Phase of Cuprates

We propose a new phase of matter, an electronic phase separation transition that starts near the upper pseudogap and segregates the holes into high and low density domains. The Cahn-Hilliard approach is used to follow quantitatively this second order transition. The resulting grain boundary potential confines the charge in domains and favors the development of intragrain superconducting amplitudes. The zero resistivity transition arises only when the intergrain Josephson coupling $E_J$ is of the order of the thermal energy and phase locking among the superconducting grains takes place. We show that this approach explains the pseudogap and superconducting phases in a natural way and reproduces some recent scanning tunneling microscopy dataComment: 4 pages and 5 eps fig

Task planning and control synthesis for robotic manipulation in space applications

Space-based robotic systems for diagnosis, repair and assembly of systems will require new techniques of planning and manipulation to accomplish these complex tasks. Results of work in assembly task representation, discrete task planning, and control synthesis which provide a design environment for flexible assembly systems in manufacturing applications, and which extend to planning of manipulatiuon operations in unstructured environments are summarized. Assembly planning is carried out using the AND/OR graph representation which encompasses all possible partial orders of operations and may be used to plan assembly sequences. Discrete task planning uses the configuration map which facilitates search over a space of discrete operations parameters in sequential operations in order to achieve required goals in the space of bounded configuration sets

Enfoque multiobjetivo para determinação de Benchmarks de companhias aéreas brasileiras DEA-ineficientes.

Este trabalho usa os resultados obtidos no modelo de Análise de Envoltória de Dados que determina quais as companhias aéreas brasileiras eficientes em vendas, no triênio 1998-1999-2000. Ao invés de serem exploradas as características das companhias eficientes, pretende-se mostras opções de melhora paras as companhias ineficientes, através das companhias que lhes servem de referência (benchmarks). Tal procedimento utiliza um enfoque de Programação Linear Multiobjeto, devido a algumas limitações dos modelos DEA clássicos. Este enfoque permite a escolha de uma meta dentre um conjunto possível de empresas eficiente

Theory of the Diamagnetism Above the Critical Temperature for Cuprates

Recently experiments on high critical temperature superconductors has shown that the doping levels and the superconducting gap are usually not uniform properties but strongly dependent on their positions inside a given sample. Local superconducting regions develop at the pseudogap temperature ($T^*$) and upon cooling, grow continuously. As one of the consequences a large diamagnetic signal above the critical temperature ($T_c$) has been measured by different groups. Here we apply a critical-state model for the magnetic response to the local superconducting domains between $T^*$ and $T_c$ and show that the resulting diamagnetic signal is in agreement with the experimental results.Comment: published versio

Pastos e manejo do pastejo de áreas dependentes de chuva.

Sistemas pecuários de produção em condições de sequeiro. Manipulação da vegetação da caatinga para exploração pecuária. Caatinga rebaixada. Caatinga raleada. Caatinga rebaixada-raleada. Caatinga enriquecida. Caatinga desmatada. Sugestões de modelos de exploração e de tecnologias com potencial para manter a sustentabilidade da produção agropecuária. Sistemas sem uso da caatinga e com espécies forrageiras cultivadas. Sistemas com uso da caatinga para produção animal. Sistemas com uso da caatinga para produção animal. Espécies de forrageiras apropriadas para exploração em áreas de sequeiro

A geometrical approach for fuzzy DEA frontiers.

Interval DEA frontiers are here used in situation where one input or output is subject to uncertainty in its measurement and is presented as an interval data. We built an efficient frontier without any assumption about the probability distribution function of the imprecise variable. We take into account only the minimum and the maximum values of each imprecise variable. Two frontiers are constructed: the optimistic and the pessimistic ones. We use fuzszy relationships to introduce a new efficiency index based on a set of some Fuzzy T Norms. We will explore only the case where only on single variable presents a certain degree of uncertainty