1,630 research outputs found
Effects of Domain Wall on Electronic Transport Properties in Mesoscopic Wire of Metallic Ferromagnets
We study the effect of the domain wall on electronic transport properties in
wire of ferromagnetic 3 transition metals based on the linear response
theory. We considered the exchange interaction between the conduction electron
and the magnetization, taking into account the scattering by impurities as
well. The effective electron-wall interaction is derived by use of a local
gauge transformation in the spin space. This interaction is treated
perturbatively to the second order. The conductivity contribution within the
classical (Boltzmann) transport theory turns out to be negligiblly small in
bulk magnets, due to a large thickness of the wall compared with the fermi
wavelength. It can be, however, significant in ballistic nanocontacts, as
indicated in recent experiments. We also discuss the quantum correction in
disordered case where the quantum coherence among electrons becomes important.
In such case of weak localization the wall can contribute to a decrease of
resistivity by causing dephasing. At lower temperature this effect grows and
can win over the classical contribution, in particular in wire of diameter
, being the inelastic diffusion
length. Conductance change of the quantum origin caused by the motion of the
wall is also discussed.Comment: 30 pages, 4 figures. Detailed paper of Phys. Rev. Lett. 78, 3773
(1997). Submitted to J. Phys. Soc. Jp
Transitional Complexity of Social Insect Immunity
Genomic analyses between insects are often conducted by comparing host genomes to that of Drosophila. For honey bees, this led to the claim that the evolutionary transition to eusociality resulted in a reduction of immunity-related genes. Although this claim pervades the literature, contradictory evidence exists. Many genomic studies, however, are not comparable due to methodological differences, and only focus on the physiological aspect of the immune system, thus potentially missing other immunity components. We advocate more comprehensive comparative studies, as well as the analysis of insect-associated defensive microbiotas to improve our understanding of the complexity of social insect immunity
Nitrogen availability and economic returns of various crop rotations with forage and annual crops
Non-Peer Reviewe
Nitrogen availability and economic returns of various crop rotations with forage and annual crops
Non-Peer Reviewe
On broad iron K-alpha lines in Seyfert 1 galaxies
The X-ray spectrum obtained by Tanaka et al from a long observation of the
active galaxy MCG shows a broad iron K line skewed to low
energies. The simplest interpretation of the shape of the line is that it is
due to doppler and gravitational redshifts from the inner parts of a disk about
a massive black hole. Similarly broad lines are evident in shorter observations
of several other active galaxies. In this paper we investigate other line
broadening and skewing mechanisms such as Comptonization in cold gas and
doppler shifts from outflows. We have also fitted complex spectral models to
the data of MCG to see whether the broad skewed line can be mimicked
well by other absorption or emission features. No satisfactory mechanism or
spectral model is found, thus strengthening the relativistic disk line model.Comment: uuencoded compressed postscript. The preprint is also available at
http://www.ast.cam.ac.uk/preprint/PrePrint.htm
Performance of Multi-Pixel Photon Counters for the T2K near detectors
We have developed a Multi-Pixel Photon Counter (MPPC) for the neutrino
detectors of T2K experiment. About 64,000 MPPCs have been produced and tested
in about a year. In order to characterize a large number of MPPCs, we have
developed a system that simultaneously measures 64 MPPCs with various bias
voltage and temperature. The performance of MPPCs are found to satisfy the
requirement of T2K experiment. In this paper, we present the performance of
17,686 MPPCs measured at Kyoto University.Comment: 15 pages, 14 figure
Optical detection of spin transport in non-magnetic metals
We determine the dynamic magnetization induced in non-magnetic metal wedges
composed of silver, copper and platinum by means of Brillouin light scattering
(BLS) microscopy. The magnetization is transferred from a ferromagnetic
Ni80Fe20 layer to the metal wedge via the spin pumping effect. The spin pumping
efficiency can be controlled by adding an insulating but transparent interlayer
between the magnetic and non-magnetic layer. By comparing the experimental
results to a dynamical macroscopic spin-transport model we determine the
transverse relaxation time of the pumped spin current which is much smaller
than the longitudinal relaxation time
Inverse Perovskite Oxysilicides and Oxygermanides as Candidates for Nontoxic Infrared Semiconductor and Their Chemical Bonding Nature
We have synthesized inverse-perovskite-type oxysilicides and oxygermanides represented by R3SiO and R3GeO (R = Ca and Sr) and studied their characteristics in the search for nontoxic narrow band gap semiconductors. These compounds exhibit a sharp absorption edge around 0.9 eV and a luminescence peak in the same energy range. These results indicate that the obtained materials have a direct-band electronic structure, which was confirmed by hybrid DFT calculations. These materials, made from earth abundant and nontoxic elements and with a relatively light electron/hole effective mass, represent strong candidates for nontoxic optoelectronic devices in the infrared range
PDAM: automatizando o processo de planejamento de atividades agrícolas municipais.
As ações governamentais na agricultura vem sendo descentralizadas de forma crescente nos anos 90, fazendo com que estados e municípios assumam funções mais ativas no processo de desenvolvimento agrícola. Uma dificuldade que tem sido observada é a falta de informações sistematizadas para atividades de planejamento, execução e acompanhamento das ações programadas para a agricultura municipal. O PDAM - Sistema de Suporte à Elaboração do Plano Diretor Agrícola Municipal visa suprir essa necessidade.bitstream/item/76664/1/CNPTIA-COM.TEC.-13-01.pd
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