25,697 research outputs found
Vortices in the presence of a nonmagnetic atom impurity in 2D XY ferromagnets
Using a model of nonmagnetic impurity potential, we have examined the
behavior of planar vortex solutions in the classical two-dimensional XY
ferromagnets in the presence of a spin vacancy localized out of the vortex
core. Our results show that a spinless atom impurity gives rise to an effective
potential that repels the vortex structure.Comment: 6 pages, 2 figures, RevTex
Lande g-tensor in semiconductor nanostructures
Understanding the electronic structure of semiconductor nanostructures is not
complete without a detailed description of their corresponding spin-related
properties. Here we explore the response of the shell structure of InAs
self-assembled quantum dots to magnetic fields oriented in several directions,
allowing the mapping of the g-tensor modulus for the s and p shells. We found
that the g-tensors for the s and p shells show a very different behavior. The
s-state in being more localized allows the probing of the confining potential
details by sweeping the magnetic field orientation from the growth direction
towards the in-plane direction. As for the p-state, we found that the g-tensor
modulus is closer to that of the surrounding GaAs, consistent with a larger
delocalization. These results reveal further details of the confining
potentials of self-assembled quantum dots that have not yet been probed, in
addition to the assessment of the g-tensor, which is of fundamental importance
for the implementation of spin related applications.Comment: 4 pages, 4 figure
A computationally efficient method for calculating the maximum conductance of disordered networks: Application to 1-dimensional conductors
Random networks of carbon nanotubes and metallic nanowires have shown to be
very useful in the production of transparent, conducting films. The electronic
transport on the film depends considerably on the network properties, and on
the inter-wire coupling. Here we present a simple, computationally efficient
method for the calculation of conductance on random nanostructured networks.
The method is implemented on metallic nanowire networks, which are described
within a single-orbital tight binding Hamiltonian, and the conductance is
calculated with the Kubo formula. We show how the network conductance depends
on the average number of connections per wire, and on the number of wires
connected to the electrodes. We also show the effect of the inter-/intra-wire
hopping ratio on the conductance through the network. Furthermore, we argue
that this type of calculation is easily extendable to account for the upper
conductivity of realistic films spanned by tunneling networks. When compared to
experimental measurements, this quantity provides a clear indication of how
much room is available for improving the film conductivity.Comment: 7 pages, 5 figure
Topological confinement in graphene bilayer quantum rings
We demonstrate the existence of localized electron and hole states in a
ring-shaped potential kink in biased bilayer graphene. Within the continuum
description, we show that for sharp potential steps the Dirac equation
describing carrier states close to the K (or K') point of the first Brillouin
zone can be solved analytically for a circular kink/anti-kink dot. The
solutions exhibit interfacial states which exhibit Aharonov-Bohm oscillations
as functions of the height of the potential step and/or the radius of the ring
Teste de vôo como critério de avaliação de qualidade de Trichospilus diatraeae (Hymenoptera: Eulophidae).
SICONBIOL 2011
Evaluation of Melaleuca sp. oil in the control of Pestalotiopsis longisetula. a phytopatothogenic fungus in strawberry cultivation on field conditions.
Produção de plantas transgênicas de café resistentes ao herbicida glufosinato de amônio
Plantas transgênicas de Coffea canephora P. resistentes ao herbicida glufosinato de amônio foram regeneradas a partir de explantes foliares cocultivados com Agrobacterium tumefaciens EHA105 contendo o plasmídio pCAMBIA3301, que contém os genes bar e uidA ambos sob controle do promotor 35S ou pIBI3 (3300 contendo o gene da ACC oxidase, antisenso) ou ainda bombardeados com o plasmídio pCAMBIA3301. Embriogênese somática direta foi induzida no meio contendo ¼ dos macros e metade dos micronutrientes do meio MS, constituintes orgânicos do meio B5 e 30 g.L 1 de sacarose, suplementado com 5mM N 6 ? (2isopentenil) adenina (2iP) e 10 mM de glufosinato de amônio para seleção de embriões transgênicos putativos. A presença e a integração do gene bar foram confirmados pelas análises de PCR e Southern blot. As plantas transgênicas pulverizadas com 1600 mg.L 1 do herbicida Finale que contém glufosinato como ingrediente ativo, não apresentaram sintomas de toxidez, mantiveram a coloração e continuaram crescendo normalmente na aclimatação ex vitro
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