Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly-doped silicon substrates

In this study we investigate magnetic properties, surface morphology and crystal structure in iron nanoclusters electrodeposited on lightly-doped (100) n-type silicon substrates. Our goal is to investigate the spin injection and detection in the Fe/Si lateral structures. The samples obtained under electric percolation were characterized by magnetoresistive and magnetic resonance measurements with cycling the sweeping applied field in order to understand the spin dynamics in the as-produced samples. The observed hysteresis in the magnetic resonance spectra, plus the presence of a broad peak in the non-saturated regime confirming the low field microwave absorption (LFMA), were correlated to the peaks and slopes found in the magnetoresistance curves. The results suggest long range spin injection and detection in low resistive silicon and the magnetic resonance technique is herein introduced as a promising tool for analysis of electric contactless magnetoresistive samples.Comment: 12 pages, 5 figure

A sustainable system for animal production in the brazilian semi-arid region.

In the semi-arid Northeast, there are about 1.0 million of farming units. Such units operate on a region characterized by heavy constraints in tenns of soil and water resources. The production systems show a low technological pattem, in sufficient to achieve an appropriate standard of living for the farmer, and, to avoid the continuous deterioration of the natural resources, mainly of the caatinga vegetation. Some studies have shown that the subsistence type of agriculture today practiced, only is successful on three in every ten years, and that livestock production, by its lower vulnerability to drought effects, has constituted the main anti-migration factor in the semi-and region. Results of a recent study conducted by Embrapa Semi-Arid workers, including small farms of 107 counties, confrrmed that trend, showing a gross income increase as livestock participation in the farm activities becomes higher. Research on livestock Production in Nontheast has generated a vast number of technologies, which, if adequately combined and operated, can assure, with no environrnental damage, economical levels of productivity and a more equitable distribution of the benefits

Resistência de genótipos de batata doce a insetos broqueadores de raízes tuberosas.

O objetivo desta pesquisa foi avaliar a resistência de três genotipos de batata doce aos insetos de solo Eucepes posifasciatus e Spodoptera eridania.CD-ROM. Suplemento. Trabalho apresentado no 51. Congresso Brasileiro de Olericultura, Viçosa, MG

Entanglement and scattering in quantum electrodynamics: S-matrix information from an entangled spectator particle

We consider a general quantum field relativistic scattering involving two half spin fermions, $A$ and $B$, which are initially entangled with another fermion $C$ that does not participate in the scattering dynamics. We construct general expressions for the reduced spin matrices for the out-state considering a general tripartite spin-entangled state. In particular we study an inelastic QED process at tree-level, namely $e^-e^+\rightarrow \mu^- \mu^+$ and a half spin fermion $C$ as an spectator particle which can be entangled to the $AB$ system in the following ways: W state, GHZ state, $|\text{A}^\alpha \rangle \otimes |\Psi^{\pm} \rangle_{\text{BC}}$ and $|\text{A}^\alpha \rangle \otimes |\Phi^{\pm} \rangle_{\text{BC}}$, where $\{|\Psi^{\pm} \rangle,|\Phi^{\pm} \rangle\}$ are the Bell basis states and $|\text{A}^\alpha \rangle$ is a spin superposition state of system $A$. We calculate the von-Neumann entropy variation before and after the scattering for the particle $C$ and show that spin measurements in $C$ contain numerical information about the total cross section of the process. We compare the initial states W and GHZ as well as study the role played by the parameter $\alpha$ in the evaluation of the entropy variations and the cross section encoded in the spectator particle.Comment: 12 pages, 10 figure

Theory of Second and Higher Order Stochastic Processes

This paper presents a general approach to linear stochastic processes driven by various random noises. Mathematically, such processes are described by linear stochastic differential equations of arbitrary order (the simplest non-trivial example is $\ddot x = R(t)$, where $R(t)$ is not a Gaussian white noise). The stochastic process is discretized into $n$ time-steps, all possible realizations are summed up and the continuum limit is taken. This procedure often yields closed form formulas for the joint probability distributions. Completely worked out examples include all Gaussian random forces and a large class of Markovian (non-Gaussian) forces. This approach is also useful for deriving Fokker-Planck equations for the probability distribution functions. This is worked out for Gaussian noises and for the Markovian dichotomous noise.Comment: 35 pages, PlainTex, accepted for publication in Phys Rev. E