Effect of the Canting of Local Anisotropy Axes on Ground-State Properties of a Ferrimagnetic Chain with Regularly Alternating Ising and Heisenberg Spins

The effect of the canting of local anisotropy axes on the ground-state phase diagram and magnetization of a ferrimagnetic chain with regularly alternating Ising and Heisenberg spins is exactly examined in an arbitrarily oriented magnetic field. It is shown that individual contributions of Ising and Heisenberg spins to the total magnetization basically depend on the spatial orientation of the magnetic field and the canting angle between two different local anisotropy axes of the Ising spins.Comment: 3 pages, 3 figure

H\"older mean applied to Anderson localization

The phase diagram of correlated, disordered electron systems is calculated within dynamical mean-field theory using the H\"older mean local density of states. A critical disorder strength is determined in the Anderson-Falicov-Kimball model and the arithmetically and the geometrically averages are found to be just particular means used respectively to detect or not the Anderson localization. Correlated metal, Mott insulator and Anderson insulator phases, as well as coexistence and crossover regimes are analyzed in this new perspective.Comment: 6 pages, 6 figures: Phys. Rev. B 76, 035111 (2007

Long-Range Dependence in Exchange Rates: the case of the European Monetary System

In this work we measure the evolution of the long-range dependence phenomenon of returns and volatilities of nominal British exchange rates (British pound against US dollar) futures contracts negotiated on the Chicago Mercantile Exchange from 1986 to 2004. The measurement employs the R/S classic analysis, Detrended Fluctuation Analysis and Generalized Hurst exponents, upon a 1008-observation window, which moves along the data. We obtain as a result, the effects of the 1992 European financial crises on the measurements of the long-range dependency phenomenon. After the crisis the returns of this futures contract showed no signs of the long-range memory, which existed before the crisis. The volatility presented moderate long-range memory the whole time. We also test for long-memory in European currencies inside the European Monetary System and find evidence of moderate long memory, which suggests that being inside the EMS increases predictability.

Vassoura-de-bruxa do cupuaçuzeiro na Amazônia.

Banco Ativo de germoplasma (BAG). Desenvolvimento de cultivares resistente. Avaliação da vassoura-de-bruxa em cupuaçuzeiro em condições de campo com uso de escala diagramática. Metodologia para inoculação de M. perniciosa em cupuaçuzeiro. Seleção de variáveis na avaliação de genótipos de cupuaçuzeiro. Controle cultural. Controle químico. Controle biológico e alternativo

Accuracy of a teleported trapped field state inside a single bimodal cavity

We propose a simplified scheme to teleport a superposition of coherent states from one mode to another of the same bimodal lossy cavity. Based on current experimental capabilities, we present a calculation of the fidelity that can be achieved, demonstrating accurate teleportation if the mean photon number of each mode is at most 1.5. Our scheme applies as well for teleportation of coherent states from one mode of a cavity to another mode of a second cavity, both cavities embedded in a common reservoir.Comment: 4 pages, 2 figures, in appreciation for publication in Physical Review

Thermal Effects on Photon-Induced Quantum Transport

We theoretically investigate laser induced quantum transport in a two-level quantum dot attached to electric contacts. Our approach, based on nonequilibrium Green function technique, allows to include thermal effects on the photon-induced quantum transport and excitonic coherent dynamics. By solving a set of coupled integrodifferential equations, involving correlation and propagator functions, we obtain the photocurrent and the dot occupations as a function of time. The characteristic coherent Rabi oscillations are found in both occupations and photocurrent, with two distinct sources of decoherence: incoherent tunneling and thermal fluctuations. In particular, for increasing temperature the dot becomes more thermally occupied which shrinks the amplitude of the Rabi oscillations, due to Pauli blockade. Finally, due to the interplay between photon and thermal induced electron populations, the photocurrent can switch sign as time evolves and its stationary value can be maximized by tunning the laser intensity.Comment: 5 pages, 4 figure