19,436 research outputs found
Beyond access and skills: from Moodle evaluation to digital literacies in situated practices
The paper considers the âframe of referenceâ for the discussion and evaluation of technologies for learning and teaching in Higher Education. As gaining access to existing and emerging technologies become easier to achieve, there is a need to upskill staff and consider âdigital literaciesâ as inherently interdisciplinary and situated practices
Non-vanishing spin Hall currents in disordered spin-orbit coupling systems
Spin currents that flow perpendicular to the electric field direction are
generic in metals and doped semiconductors with spin-orbit coupling. It has
recently been argued that the spin Hall conductivity can be dominated by an
intrinsic contribution which follows from Bloch state distortion in the
presence of an electric field. Here we report on an numerical demonstration of
the robustness of this effect in the presence of disorder scattering for the
case of a two-dimensional electron-gas with Rashba spin-orbit interactions
(R2DES).Comment: 4 pages, 3 figure
Digital literacies in situated practices
As gaining access to existing and emerging technologies become easier to achieve, there is a need to upskill staff and consider âdigital literaciesâ as inherently interdisciplinary and situated practices. This poster outlines the digital literacy project at Middlesex University
The Influence of Formulation, Buffering, pH and Divalent Cations on the Activity of Endothall on Hydrilla.
Endothall has been used as an aquatic herbicide for more
than 40 years and provides very effective weed control of
many weeds. Early research regarding the mechanism-of-action
of endothall contradicts the symptomology normally associated
with the product. Recent studies suggest endothall
is a respiratory toxin but the mechanism-of-action remains
unknown. To further elucidate the activity of endothall, several
endothall formulations were evaluated for their effects
on ion leakage, oxygen consumption and photosynthetic oxygen
evolution from hydrilla shoot tips. The influence of pH,
buffering and divalent cations was also evaluated. (PDF contains 6 pages.
DC-transport properties of ferromagnetic (Ga,Mn)As semiconductors
We study the dc transport properties of (Ga,Mn)As diluted magnetic
semiconductors with Mn concentration varying from 1.5% to 8%. Both diagonal and
Hall components of the conductivity tensor are strongly sensitive to the
magnetic state of these semiconductors. Transport data obtained at low
temperatures are discussed theoretically within a model of band-hole
quasiparticles with a finite spectral width due to elastic scattering from Mn
and compensating defects. The theoretical results are in good agreement with
measured anomalous Hall effect and anisotropic longitudinal magnetoresistance
data. This quantitative understanding of dc magneto-transport effects in
(Ga,Mn)As is unparalleled in itinerant ferromagnetic systems.Comment: 3 pages, 3 figure
Exact spin dynamics of the 1/r^2 supersymmetric t-J model in a magnetic field
The dynamical spin structure factor S^{zz}(Q,omega) in the small momentum
region is derived analytically for the one-dimensional supersymmetric t-J model
with 1/r^2 interaction. Strong spin-charge separation is found in the spin
dynamics. The structure factor S^{zz}(Q,omega) with a given spin polarization
does not depend on the electron density in the small momentum region. In the
thermodynamic limit, only two spinons and one antispinon (magnon) contribute to
S^{zz}(Q,omega). These results are derived via solution of the SU(2,1)
Sutherland model in the strong coupling limit.Comment: 20 pages, 8 figures. Accepted for publication in J.Phys.
Land use change detection with LANDSAT-2 data for monitoring and predicting regional water quality degradation
The author has identified the following significant results. Comparison between LANDSAT 1 and 2 imagery of Arkansas provided evidence of significant land use changes during the 1972-75 time period. Analysis of Arkansas historical water quality information has shown conclusively that whereas point source pollution generally can be detected by use of water quality data collected by state and federal agencies, sampling methodologies for nonpoint source contamination attributable to surface runoff are totally inadequate. The expensive undertaking of monitoring all nonpoint sources for numerous watersheds can be lessened by implementing LANDSAT change detection analyses
Non-equilibrium Entanglement and Noise in Coupled Qubits
We study charge entanglement in two Coulomb-coupled double quantum dots in
thermal equilibrium and under stationary non-equilibrium transport conditions.
In the transport regime, the entanglement exhibits a clear switching threshold
and various limits due to suppression of tunneling by Quantum Zeno localisation
or by an interaction induced energy gap. We also calculate quantum noise
spectra and discuss the inter-dot current correlation as an indicator of the
entanglement in transport experiments.Comment: 4 pages, 4 figure
Current noise of a quantum dot p-i-n junction in a photonic crystal
The shot-noise spectrum of a quantum dot p-i-n junction embedded inside a
three-dimensional photonic crystal is investigated. Radiative decay properties
of quantum dot excitons can be obtained from the observation of the current
noise. The characteristic of the photonic band gap is revealed in the current
noise with discontinuous behavior. Applications of such a device in
entanglement generation and emission of single photons are pointed out, and may
be achieved with current technologies.Comment: 4 pages, 3 figures, to appear in Phys. Rev. B (2005
Magnetic Anisotropy in Quantum Hall Ferromagnets
We show that the sign of magnetic anisotropy energy in quantum Hall
ferromagnets is determined by a competition between electrostatic and exchange
energies. Easy-axis ferromagnets tend to occur when Landau levels whose states
have similar spatial profiles cross. We report measurements of integer QHE
evolution with magnetic-field tilt. Reentrant behavior observed for the QHE at high tilt angles is attributed to easy-axis anisotropy. This
interpretation is supported by a detailed calculation of the magnetic
anisotropy energy.Comment: 12 pages, 3 figures, submitted to Phys. Rev. Let
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