Temperature dependence of the nonlocal voltage in an Fe/GaAs electrical spin injection device

The nonlocal spin resistance is measured as a function of temperature in a Fe/GaAs spin-injection device. For nonannealed samples that show minority-spin injection, the spin resistance is observed up to room temperature and decays exponentially with temperature at a rate of 0.018\,K$^{-1}$. Post-growth annealing at 440\,K increases the spin signal at low temperatures, but the decay rate also increases to 0.030\,K$^{-1}$. From measurements of the diffusion constant and the spin lifetime in the GaAs channel, we conclude that sample annealing modifies the temperature dependence of the spin transfer efficiency at injection and detection contacts. Surprisingly, the spin transfer efficiency increases in samples that exhibit minority-spin injection.Comment: 10 pages, 4 figure

PENGEMBANGAN OBJEK WISATA WIDURI WATER PARK DI KABUPATEN PEMALANG

Widuri Water Park is one of potential tourist attraction, has been build and worthy of being an icon of tourism in Pemalang regency. Potential possessed by Widuri Water park among others, is a very strategic location, has a charming, dilightful an ideal as a place of recreation. Neverthless, during the years 2010-2014 the number of visitor attractions of Widuri Water Park decreased from year to year. This research aims to determine the development strategy that should prioritize to increase the number of visitor of tourist attraction Widuri Water Park in Pemalang Regency. This study uses Analysis Hierarchy Process (AHP). This method is used to analyze 10 policies of alternative development tourist attraction Widuri Water Park proposed by the Key Person which has been through interview process before. Alternatives are divided into three aspects; promotion aspect, infrastructure aspect, and management aspect. The whole of these alternatives will be analyzed by two different types of respondents; thas is the Key Person and the visitor of tourist attraction. The Key Person as many as 5 respondenst, that is from academics, businessman, goverment and community and then the visitor of tourist attraction Widuri Water Park in Pemalang Regency by 30 respondents. The result of this study based on the overall alternative to the three aspects by each respondent prioritized for developing of tourist attraction Widuri Water Park is to perform maintenance rides regularly with inconsistency ratio of 0.05 or less than 0.10, which means that this analysis is consistent and acceptable to be a priority in the development of tourist attraction Widuri Water Park. Alternative of perform maintenance rides regularly is the highest priority among other alternatives

Inverse Compton scattering on laser beam and monochromatic isotropic radiation

Most of the known literature on Inverse Compton Scattering (ICS) is based on earliest theoretical attempts and later approximations led by F.C.Jones and J.B.Blumenthal. We found an independent and more general analytical procedure which provide both relativistic and ultrarelativistic limits for ICS. These new analytical expressions can be derived in a straightforward way and they contain the previously reminded Jones' results. Our detailed solutions may be probed by already existing as well future ICS experiments

Effect of exchange interaction on fidelity of quantum state transfer from a photon qubit to an electron-spin qubit

We analyzed the fidelity of the quantum state transfer (QST) from a photon-polarization qubit to an electron-spin-polarization qubit in a semiconductor quantum dot, with special attention to the exchange interaction between the electron and the simultaneously created hole. In order to realize a high-fidelity QST we had to separate the electron and hole as soon as possible, since the electron-hole exchange interaction modifies the orientation of the electron spin. Thus, we propose a double-dot structure to separate the electron and hole quickly, and show that the fidelity of the QST can reach as high as 0.996 if the resonant tunneling condition is satisfied.Comment: 5 pages, 4 figures, to be published in Phys. Rev. B Rapid Communication

Orbital assembly and maintenance study

The requirements, conceptual design, tradeoffs, procedures, and techniques for orbital assembly of the support structure of the microwave power transmission system and the radio astronomy telescope are described. Thermal and stress analyses, packaging, alignment, and subsystems requirements are included along with manned vs. automated and transportation tradeoffs. Technical and operational concepts for the manned and automated maintenance of satellites were investigated and further developed results are presented

Two-dimensional imaging of the spin-orbit effective magnetic field

We report on spatially resolved measurements of the spin-orbit effective magnetic field in a GaAs/InGaAs quantum-well. Biased gate electrodes lead to an electric-field distribution in which the quantum-well electrons move according to the local orientation and magnitude of the electric field. This motion induces Rashba and Dresselhaus effective magnetic fields. The projection of the sum of these fields onto an external magnetic field is monitored locally by measuring the electron spin-precession frequency using time-resolved Faraday rotation. A comparison with simulations shows good agreement with the experimental data.Comment: 6 pages, 4 figure

Orbital assembly and maintenance study. Executive summary

A sound, practical approach for the assembly and maintenance of very large structures in space is presented. The methods and approaches for assembling two large structures are examined. The maintenance objectives include the investigation of methods to maintain five geosynchronous satellites. The two assembly examples are a 200-meter-diameter radio astronomy telescope and a 1,000-meter-diameter microwave power transmission system. The radio astronomy telescope operates at an 8,000-mile altitude and receives RF signals from space. The microwave power transmission system is part of a solar power satellite that will be used to transmit converted solar energy to microwave ground receivers. Illustrations are included

Idade e ritmo de crescimento do tronco de árvores de espécies da Floresta Natural do Pantanal Matogrossensse, MS.

Informações sobre a influência de fatores ambientais na taxa de crescimento das espécies arbóreas são importantes para o manejo de florestas naturais ou plantadas, sendo os anéis de crescimento uma ferramenta adequada para essas análises. Objetivou-se com este trabalho determinar a idade e os incrementos radiais do tronco de árvores de 19 espécies de florestas naturais do Pantanal da Nhecolândia, pelo estudo dos anéis de crescimento. A coleta dos discos do caule das árvores foi realizada na fazenda Nhumirim, da Embrapa Pantanal, localizada na sub-região da Nhecolândia, município de Corumbá, Mato Grosso do Sul. As árvores de 19 espécies foram selecionadas pela boa forma da copa em áreas de vegetação de cerrado (Savana Arborizada), cerradão (Savana Florestada), e mata (Floresta Estacional Semidecidual), sendo coletados discos do lenho 0,30 m do solo para a determinação da idade e do incremento médio nos 5 primeiros anos e 1,30 m para a avaliação do ritmo de crescimento. Os anéis de crescimento foram contados e medidos em 8 raios de cada disco. Os incrementos radiais médios anuais das espécies arbóreas estudadas apresentaram grande amplitude, variando de 0,21 a 0,94 cm em árvores de 10 a 31 anos