3,458 research outputs found
Magnetic Field Effects on the Transport Properties of One-sided Rough Wires
We present a detailed numerical analysis of the effect of a magnetic field on
the transport properties of a `small-' one-sided surface disordered wire.
When time reversal symmetry is broken due to a magnetic field , we find a
strong increase with not only of the localization length but also of
the mean free path caused by boundary states. Despite this, the
universal relationship between and does hold. We also analyze the
conductance distribution at the metal-insulator crossover, finding a very good
agreement with Random Matrix Theory with two fluctuating channels within the
Circular Orthogonal(Unitary) Ensemble in absence(presence) of Comment: 5 pages, 4 figures, to appear in Phys. Rev.
Universal Conductance Distributions in the Crossover between Diffusive and Localization Regimes
The full distribution of the conductance in quasi-one-dimensional
wires with rough surfaces is analyzed from the diffusive to the localization
regime. In the crossover region, where the statistics is dominated by only one
or two eigenchannels, the numerically obtained P(G) is found to be independent
of the details of the system with the average conductance as the only
scaling parameter. For < e^2/h, P(G) is given by an essentially
``one-sided'' log-normal distribution. In contrast, for e^2/h <= 2e^2/h,
the shape of P(G) remarkable agrees with those predicted by random matrix
theory for two fluctuating transmission eigenchannels.Comment: Accepted for publication in Phys. Rev. Let
On The spectrum of a Noncommutative Formulation of the D=11 Supermembrane with Winding
A regularized model of the double compactified D=11 supermembrane with
nontrivial winding in terms of SU(N) valued maps is obtained. The condition of
nontrivial winding is described in terms of a nontrivial line bundle introduced
in the formulation of the compactified supermembrane. The multivalued
geometrical objects of the model related to the nontrivial wrapping are
described in terms of a SU(N) geometrical object which in the
limit, converges to the symplectic connection related to the area preserving
diffeomorphisms of the recently obtained non-commutative description of the
compactified D=11 supermembrane.(I. Martin, J.Ovalle, A. Restuccia. 2000,2001)
The SU(N) regularized canonical lagrangian is explicitly obtained. In the limit it converges to the lagrangian in (I.Martin, J.Ovalle,
A.Restuccia. 2000,2001) subject to the nontrivial winding condition. The
spectrum of the hamiltonian of the double compactified D=11 supermembrane is
discussed.
Generically, it contains local string like spikes with zero energy.
However the sector of the theory corresponding to a principle bundle
characterized by the winding number , described by the SU(N) model we
propose, is shown to have no local string-like spikes and hence the spectrum of
this sector should be discrete.Comment: 16 pages.Latex2
Generalized scattering-matrix approach for magneto-optics in periodically patterned multilayer systems
We present here a generalization of the scattering-matrix approach for the
description of the propagation of electromagnetic waves in nanostructured
magneto-optical systems. Our formalism allows us to describe all the key
magneto-optical effects in any configuration in periodically patterned
multilayer structures. The method can also be applied to describe periodic
multilayer systems comprising materials with any type of optical anisotropy. We
illustrate the method with the analysis of a recent experiment in which the
transverse magneto-optical Kerr effect was measured in a Fe film with a
periodic array of subwavelength circular holes. We show, in agreement with the
experiments, that the excitation of surface plasmon polaritons in this system
leads to a resonant enhancement of the transverse magneto-optical Kerr effect.Comment: 12 pages, 6 figures, submitted to Physical Review
Exchange bias in laterally oxidized Au/Co/Au nanopillars
Au/Co/Au nanopillars fabricated by colloidal lithography of continuous
trilayers exhibit and enhanced coercive field and the appearance of an exchange
bias field with respect to the continuous layers. This is attributed to the
lateral oxidation of the Co interlayer that appears upon disc fabrication. The
dependence of the exchange bias field on the Co nanodots size and on the
oxidation degree is analyzed and its microscopic origin clarified by means of
Monte Carlo simulations based on a model of a cylindrical dot with lateral
core/shell structure.Comment: 8 pages, 4 figures. Published in Appl. Phys. Let
Experimental status of the isoscalar S wave at low energy: pole and scattering length
The experimental results obtained in the last few years on kaon decays
(K and, above all, Ke4 decays) allow a reliable, model independent
determination of low energy scattering in the S0 wave. Using them and,
eventually, other sets of data, it is possible to give a precise
parametrization of the S0 wave as well as to find the scattering length and
effective range parameter. One can also perform an extrapolation to the pole of
the " resonance" []. We obtain the results
and, for the pole, M_\sigma=484\pm17 \mev,\quad\gammav_\sigma/2=
255\pm10 {\rm MeV}.Comment: Plain TeX;4 figures; improved data used; version to appear in Phys.
Rev.
Influence of the magnetic field on the plasmonic properties of transparent Ni anti-dot arrays
Extraordinary optical transmission is observed due to the excitation of
surface plasmon polaritons (SPPs) in 2-Dimensional hexagonal anti-dot patterns
of pure Ni thin films, grown on sapphire substrates. A strong enhancement of
the polar Kerr rotation is recorded at the surface plasmon related transmission
maximum. Angular resolved reflectivity measurements under an applied field,
reveal an enhancement and a shift of the normalized reflectivity difference
upon reversal of the magnetic saturation (transverse magneto-optical Kerr
effect-TMOKE). The change of the TMOKE signal clearly shows the magnetic field
modulation of the dispersion relation of SPPs launched in a 2D patterned
ferromagnetic Ni film
The role of scenario, deontic conditionals and problem content in Wason´s selection task
This paper was presented at "The European Conference on Cognitive Science. Siena, Italy, October 1999"This experiment explores the influence of thematic content, the presence or
absence of a scenario and the use of deontic or indicative framing of
conditional rules on performance on Wason’s selection task. Logical
performance was affected by the content used (permission rules were the
best, neutral the worst and obligation rules intermediate) and by the use of
scenarios. The scenario effect interacted significantly with the problem
framing such that the presence of a scenario facilitate performance only
when problems were framed in a deontic rather than indicative manner.
The presence of scenarios did not interact with the problem content. These
results are discussed in terms of pragmatic influences on reasoning, within
the framework of the Dual Process Theory (Evans & Over, 1996
Gypsum mining spoil improves plant emergence and growth in soils polluted with potentially harmful elements
Purpose Soil pollution is a major problem worldwide.
Some anthropogenic activities, such as mining, may
exceed soil capacity, causing relevant health and ecosystem
hazards. The use of mineral amendments can
help reduce soil pollution. Gypsum mining spoil (GS)
is a waste material highly produced in gypsum mining
industry, which has never been used in soil remediation
despite its high potential as amendment of polluted
soils. In this study, we carried out an ex-situ experiment
to assess for the first time the capacity of GS to both
reduce the availability of Potentially Harmful Elements
(PHEs) in soils and promote seed emergence.
Methods Soils affected by residual pollution after
the Aznalcóllar mine spill were collected, treated with GS in three different proportions, and sown
with seeds of two non-genetically related species.
Seed emergence and biomass production were
monitored, and PHE content in soils and plants
were analysed.
Results We have observed a direct and very positive
relation between GS and both the reduction of PHE
availability and PHE uptake by plants, and the increase
of plant emergence and growth, especially with the
addition of the highest doses of the amendment.
Conclusion This study highlights the promising
results of GS as a novel soil amendment to be used
in the remediation of polluted soils and vegetation
recovery. Moreover, using GS as soil amendment
will bring the opportunity to sustainably manage this
waste material and reduce its social and environmental
impact parallelly to the mitigation of PHE hazards.KNAUF-GmbHMinistry of Science, Innovation and Universities RTI 2018-094327-B-I00Tatiana-Perez-de-Guzman-el-Bueno Foundation PhD grant Programme 201
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