5,971 research outputs found
Management system requirements for wireless systems beyond 3G
This paper presents a comprehensive description of various management system requirements for systems beyond 3G, which have been identified as a result of the Software Based Systems activities within the Mobile VCE Core 2 program. Specific requirements for systems beyond 3G are discussed and potential technologies to address them proposed. The analysis has been carried out from network, service and security viewpoints
Longitudinal variations, the opposition effect and monochromatic albedos for Mars
Magnitude at zero phase, phase coefficient, and monochromatic albedo computed for Mars as function of wavelengt
Voltage-controlled electron tunnelling from a single self-assembled quantum dot embedded in a two-dimensional-electron-gas-based photovoltaic cell
We perform high-resolution photocurrent (PC) spectroscopy to investigate
resonantly the neutral exciton ground-state (X0) in a single InAs/GaAs
self-assembled quantum dot (QD) embedded in the intrinsic region of an
n-i-Schottky photodiode based on a two-dimensional electron gas (2DEG), which
was formed from a Si delta-doped GaAs layer. Using such a device, a single-QD
PC spectrum of X0 is measured by sweeping the bias-dependent X0 transition
energy through that of a fixed narrow-bandwidth laser via the quantum-confined
Stark effect (QCSE). By repeating such a measurement for a series of laser
energies, a precise relationship between the X0 transition energy and bias
voltage is then obtained. Taking into account power broadening of the X0
absorption peak, this allows for high-resolution measurements of the X0
homogeneous linewidth and, hence, the electron tunnelling rate. The electron
tunnelling rate is measured as a function of the vertical electric field and
described accurately by a theoretical model, yielding information about the
electron confinement energy and QD height. We demonstrate that our devices can
operate as 2DEG-based QD photovoltaic cells and conclude by proposing two
optical spintronic devices that are now feasible.Comment: 34 pages, 11 figure
Increases in use of novel synthetic stimulant are not directly linked to decreased use of 3,4-methylenedioxy-N-methylamphetamine (MDMA)
A decline in 3,4-methylenedioxy-N-methylamphetamine (MDMA) use in Adelaide, Australia from 2009 to 2010 was confirmed by us previously. Reports suggested that the shortage in MDMA supply was associated with an increased prevalence of other synthetic stimulants, but quantitative measurements were unavailable. To obtain objective data on the community use of synthetic stimulants, we collected wastewater samples from multiple treatment plants in Adelaide, Australia from 2009 to 2011 and analysed them using solid-phase extraction/liquid chromatography/tandem mass spectrometry (SPE-LC-MS/MS), targeting MDMA and some of the most reported synthetic cathinones and piperazines. Data were temporally compared. MDMA and six other synthetic stimulants were detected and quantified in wastewater samples. While MDMA level decreased markedly from 2009 to 2010 and remained low in 2011, localized increased use of mephedrone, methylone, methylenedioxypyrovalerone (MDPV), benzylpiperazine (BZP), 3-trifluoromethylphenylpiperazine (TFMPP), but not methcathinone, was observed in 2010 and 2011. This suggested that the decline in MDMA use was associated with an increase in the use of a number of other synthetic stimulants. However, the lag time from the decrease in MDMA to the increase in use of a number of these stimulants, together with the highly regionalized use of all synthetic stimulants except methcathinone indicates that there was no direct population wide substitution in response to the reduction in MDMA.Chang Chen, Chris Kostakis, Rodney J. Irvine, Jason M. Whit
Spin gating electrical current
We use an aluminium single electron transistor with a magnetic gate to
directly quantify the chemical potential anisotropy of GaMnAs materials.
Uniaxial and cubic contributions to the chemical potential anisotropy are
determined from field rotation experiments. In performing magnetic field sweeps
we observe additional isotropic magnetic field dependence of the chemical
potential which shows a non-monotonic behavior. The observed effects are
explained by calculations based on the kinetic
exchange model of ferromagnetism in GaMnAs. Our device inverts the conventional
approach for constructing spin transistors: instead of spin-transport
controlled by ordinary gates we spin-gate ordinary charge transport.Comment: 5 pages, 4 figure
- …