6,424 research outputs found
ICE-TheOREM - End to End Semantically Aware eResearch Infrastructure for Theses
4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PresentationsDate: 2009-05-19 10:00 AM – 11:30 AMICE-TheOREM was a project which made several important contributions to the repository domain, promoting deposit by integrating the repository with authoring workflows and enhancing open access, by adding new infrastructure to allow fine-grained embargo management within an institution without impacting on existing open access repository infrastructure.
In the area of scholarly communications workflows, the project produced a complete end-to-end demonstration of eScholarship for word processor users, with tools for authoring, managing and disseminating semantically-rich thesis documents fully integrated with supporting data. This work is focused on theses, as it is well understood that early career researchers are the most likely to lead the charge in new innovations in scholarly publishing and dissemination models.
The authoring tools are built on the ICE content management system, which allows authors to work within a word processing system (as most authors do) with easy-to-use toolbars to structure and format their documents. The ICE system manages both small data files and links to larger data sets. The result is research publication which are available not just as paper-ready PDF files but as fully interactive semantically aware web documents which can be disseminated via repository software such as ePrints, DSpace and Fedora as complete supported web-native
One the technological side, ICE-TheOREM implemented the Object Reuse and Exchange (ORE) protocol to integrate between a content management system, a thesis management system and multiple repository software packages and looked at ways to describe aggregate objects which include both data and documents, which can be generalized to domains other than chemistry. ICE-TheOREM has demonstrated how focusing on the use of the web architecture (including ORE) enables repository functions to be distributed between systems for complex, data-rich compound objects.UK Joint Information Systems Committee (JISC
Localization of massless Dirac particles via spatial modulations of the Fermi velocity
The electrons found in Dirac materials are notorious for being difficult to
manipulate due to the Klein phenomenon and absence of backscattering. Here we
investigate how spatial modulations of the Fermi velocity in two-dimensional
Dirac materials can give rise to localization effects, with either full
(zero-dimensional) confinement or partial (one-dimensional) confinement
possible depending on the geometry of the velocity modulation. We present
several exactly solvable models illustrating the nature of the bound states
which arise, revealing how the gradient of the Fermi velocity is crucial for
determining fundamental properties of the bound states such as the zero-point
energy. We discuss the implications for guiding electronic waves in few-mode
waveguides formed by Fermi velocity modulation.Comment: 9 pages, 6 figure
Charged Particle Radiation Damage in Semiconductors, I- Experimental Proton Irradiation of Solar Cells
Proton irradiation of solar cell
One-dimensional Coulomb problem in Dirac materials
We investigate the one-dimensional Coulomb potential with application to a
class of quasirelativistic systems, so-called Dirac-Weyl materials, described
by matrix Hamiltonians. We obtain the exact solution of the shifted and
truncated Coulomb problems, with the wavefunctions expressed in terms of
special functions (namely Whittaker functions), whilst the energy spectrum must
be determined via solutions to transcendental equations. Most notably, there
are critical bandgaps below which certain low-lying quantum states are missing
in a manifestation of atomic collapse.Comment: 7 pages, 5 figure
Bielectron vortices in two-dimensional Dirac semimetals
Searching for new states of matter and unusual quasiparticles in emerging
materials and especially low-dimensional systems is one of the major trends in
contemporary condensed matter physics. Dirac materials, which host
quasiparticles which are described by ultrarelativistic Dirac-like equations,
are of a significant current interest from both a fundamental and applied
physics perspective. Here we show that a pair of two-dimensional massless
Dirac-Weyl fermions can form a bound state independently of the sign of the
inter-particle interaction potential, as long as this potential decays at large
distances faster than Kepler's inverse distance law. This leads to the
emergence of a new type of energetically-favourable quasiparticle: bielectron
vortices, which are double-charged and reside at zero-energy. Their bosonic
nature allows for condensation and may give rise to Majorana physics without
invoking a superconductor. These novel quasiparticles arguably explain a range
of poorly understood experiments in gated graphene structures at low doping.Comment: 9 pages, 2 figure
Massless Dirac fermions in two dimensions: Confinement in nonuniform magnetic fields
We show how it is possible to trap two-dimensional massless Dirac fermions in
spatially inhomogeneous magnetic fields, as long as the formed magnetic quantum
dot (or ring) is of a slowly decaying nature. It is found that a modulation of
the depth of the magnetic quantum dot leads to successive
confinement-deconfinement transitions of vortexlike states with a certain
angular momentum, until a regime is reached where only states with one sign of
angular momentum are supported. We illustrate these characteristics with both
exact solutions and a hitherto unknown quasi-exactly solvable model utilizing
confluent Heun functions.Comment: 7 pages, 3 figure
Prey body size mediates the predation risk associated with being "odd"
Despite selection pressures on prey animals to maintain phenotypically homogeneous groups, variation in phenotype within animal groups is commonly observed. Although many prey animals preferentially associate with size-matched individuals, a lack of preference or a preference for nonmatching group mates is also commonly observed. We suggest that the assortative response to predation risk may be mediated by body size because larger bodied prey may be at greater risk of predation than smaller bodied prey when in a mixed group due to their greater potential profitability. We test this idea by observing attacks by three-spine sticklebacks Gasterosteus aculeatus on mixed groups of large and small Daphnia magna prey. We find that smaller Daphnia are at greatest risk when they form the majority of the group, whereas larger Daphnia are at the greatest predation risk when they form the minority. Thus, we predict that both large and small prey should benefit by association with large prey, generating a potential conflict over group membership that may lead to the mixed phenotype groups we observe in nature
Compact Binaries in Star Clusters II - Escapers and Detection Rates
We use a self-consistent Monte Carlo treatment of stellar dynamics to
investigate black hole binaries that are dynamically ejected from globular
clusters to determine if they will be gravitational wave sources. We find that
many of the ejected binaries have initially short periods and will merge within
a Hubble time due to gravitational wave radiation. Thus they are potential
sources for ground-based gravitational wave detectors. We estimate the yearly
detection rate for current and advanced ground-based detectors and find a
modest enhancement over the rate predicted for binaries produced by pure
stellar evolution in galactic fields. We also find that many of the ejected
binaries will pass through the longer wavelength Laser Interferometer Space
Antenna (LISA) band and may be individually resolvable. We find a low
probability that the Galaxy will contain a binary in the LISA band during its
three-year mission. Some such binaries may, however, be detectable at Mpc
distances implying that there may be resolvable stellar-mass LISA sources
beyond our Galaxy. We conclude that globular clusters have a significant effect
on the detection rate of ground-based detectors and may produce interesting
LISA sources in local group galaxies.Comment: 19 pages, 16 figures, 2 tables, submitted to MNRA
- …