Carbon nanotube: a low-loss spin-current waveguide

We demonstrate with a quantum-mechanical approach that carbon nanotubes are excellent spin-current waveguides and are able to carry information stored in a precessing magnetic moment for long distances with very little dispersion and with tunable degrees of attenuation. Pulsed magnetic excitations are predicted to travel with the nanotube Fermi velocity and are able to induce similar excitations in remote locations. Such an efficient way of transporting magnetic information suggests that nanotubes are promising candidates for memory devices with fast magnetization switchings

Clocked Atom Delivery to a Photonic Crystal Waveguide

Experiments and numerical simulations are described that develop quantitative understanding of atomic motion near the surfaces of nanoscopic photonic crystal waveguides (PCWs). Ultracold atoms are delivered from a moving optical lattice into the PCW. Synchronous with the moving lattice, transmission spectra for a guided-mode probe field are recorded as functions of lattice transport time and frequency detuning of the probe beam. By way of measurements such as these, we have been able to validate quantitatively our numerical simulations, which are based upon detailed understanding of atomic trajectories that pass around and through nanoscopic regions of the PCW under the influence of optical and surface forces. The resolution for mapping atomic motion is roughly 50 nm in space and 100 ns in time. By introducing auxiliary guided mode (GM) fields that provide spatially varying AC-Stark shifts, we have, to some degree, begun to control atomic trajectories, such as to enhance the flux into to the central vacuum gap of the PCW at predetermined times and with known AC-Stark shifts. Applications of these capabilities include enabling high fractional filling of optical trap sites within PCWs, calibration of optical fields within PCWs, and utilization of the time-dependent, optically dense atomic medium for novel nonlinear optical experiments

Características bromatológicas de acessos de moringa.

O Banco Ativo de Germoplasma da Embrapa Tabuleiros Costeiros possui 18 acessos instalados no município de Nossa Senhora das Dores, Sergipe, Brasil. O objetivo do presente trabalho foi avaliar algumas características bromatológicas desses acessos, como os teores de matéria seca, proteína bruta, extrato etéreo e cinzas. As análises foram realizadas no Laboratório de Nutrição Animal da Embrapa Tabuleiros Costeiros. O delineamento experimental foi inteiramente casualizado, com 18 tratamentos (acessos) e três repetições (épocas de corte). Não houve diferença significativa entre os acessos, que apresentaram valores médios de 19,21% (MS), 23,69% (PB), 7,29% (EE) e 10,04% (CZ)

Características morfoagronômicas e bromatológicas de acessos de nim indiano.

No Nordeste brasileiro, o nim foi amplamente difundido e utilizado na arborização urbana, na utilização de frutos em escala industrial e é também uma opção para lenha. Em 2009, a Embrapa Tabuleiros Costeiros, acreditando no seu potencial para extração de óleo, implantou um Banco de Germoplasma da espécie, em Aracaju. Ainda em fase de ampliação, o BAG é avaliado constantemente. O objetivo do presente trabalho foi avaliar algumas características bromatológicas e morfológicas, no período de 2013-2014. Avaliou-se os teores de matéria seca, de proteína bruta e extrato etéreo, além da altura da planta (h), inserção da copa (IC), diâmetro do caule (DC), diâmetro à altura do peito (DAP) e raio da copa (RC). Quanto aos descritores morfológicos avaliados, não houve diferença signifi cativa entre as espécies. A análise bromatológica resultou em 28,92% de matéria seca, 6,87% de proteína bruta e 16,97% de extrato etéreo

Colheita e armazenamento de sementes de coentro.

Made available in DSpace on 2011-04-09T16:13:50Z (GMT). No. of bitstreams: 1 nascimentocolheita.pdf: 1775148 bytes, checksum: 55e9ecfa2f8f7b5b443ff8e6687a2648 (MD5) Previous issue date: 2007-03-2

Exponential behavior of the interlayer exchange coupling across non-magnetic metallic superlattices

It is shown that the coupling between magnetic layers separated by non-magnetic metallic superlattices can decay exponentially as a function of the spacer thickness $N$, as opposed to the usual $N^{-2}$ decay. This effect is due to the lack of constructive contributions to the coupling from extended states across the spacer. The exponential behavior is obtained by properly choosing the distinct metals and the superlattice unit cell composition.Comment: To appear in Phys. Rev.

Capture Velocity for a Magneto-Optical Trap in a Broad Range of Light Intensity

In a recent paper, we have used the dark-spot Zeeman tuned slowing technique [Phys. Rev. A 62, 013404-1, (2000)] to measure the capture velocity as a function of laser intensity for a sodium magneto optical trap. Due to technical limitation we explored only the low light intensity regime, from 0 to 27 mW/cm^2. Now we complement that work measuring the capture velocity in a broader range of light intensities (from 0 to 400 mW/cm^2). New features, observed in this range, are important to understant the escape velocity behavior, which has been intensively used in the interpretation of cold collisions. In particular, we show in this brief report that the capture velocity has a maximum as function of the trap laser intensity, which would imply a minimum in the trap loss rates.Comment: 2 pages, 2 figure

Evaluation of Fertilizing Methods on the Establishment of Pasture Species on Native Pasture by Direct Sowing

The experiment was carried out in the southern of Brazil, by direct sowing ryegrass (Lolium multiflorum), white clover (Trifolium repens), birds foot trifolium (Lotus corniculatus) and red clover (Trifolium pratensis) on native pasture. Herbicide Glyfosate was previously applied on this native pasture. The treatments were T1 -seed sowing in row with half fertilizer in row and half broadcasting; T2 – seed sowing in row with all fertilizer in row; T3 – seed sowing in row and all fertilizer broadcasting; T4 – seed and fertilizer broadcasting. The pasture was evaluated by two cuts in 1998 and three cuts in 1999. Considering cut means for two years, treatments T1 and T2 produced the higher dry matter yield and no difference were observed between them, however, both treatments differed (P\u3c 0.05) from T3 and T4. The best legume-grass mixture in the pasture were obtained in the treatments T1 and T2