916 research outputs found
Self- and peer-assessment: evidence from the accounting and finance discipline.
Self- and peer-assessment of student work is an area that is under-researched in the accounting education literature, although the subject area of study seems to influence the results obtained in prior studies. The current study contributes to the literature by examining the accuracy and construct validity of self- and peer-assessment by accounting students. It also investigates students' views about these exercises. The findings show that whilst the self- and peer-assessment of students appear to be neither accurate nor valid, the students are positive about the impact of these procedures on their learning experience. These findings indicate that, although instructors might not rely on self- and peer-assessment as measures of students' performance for the purpose of summative assessment, the exercise may prove useful for formative assessment because it can promote a wide range of transferable skills
Dynamically Warped Theory Space and Collective Supersymmetry Breaking
We study deconstructed gauge theories in which a warp factor emerges
dynamically and naturally. We present nonsupersymmetric models in which the
potential for the link fields has translational invariance, broken only by
boundary effects that trigger an exponential profile of vacuum expectation
values. The spectrum of physical states deviates exponentially from that of the
continuum for large masses; we discuss the effects of such exponential towers
on gauge coupling unification. We also present a supersymmetric example in
which a warp factor is driven by Fayet-Iliopoulos terms. The model is peculiar
in that it possesses a global supersymmetry that remains unbroken despite
nonvanishing D-terms. Inclusion of gravity and/or additional messenger fields
leads to the collective breaking of supersymmetry and to unusual phenomenology.Comment: 28 pages LaTeX, JHEP format, 7 eps figures (v2: reference added
The robot vibrissal system: Understanding mammalian sensorimotor co-ordination through biomimetics
Chapter 10 The Robot Vibrissal System: Understanding Mammalian Sensorimotor Co-ordination Through Biomimetics Tony J. Prescott, Ben Mitchinson, Nathan F. Lepora, Stuart P. Wilson, Sean R. Anderson, John Porrill, Paul Dean, Charles ..
Low field vortex matter in YBCO: an atomic beam magnetic resonance study
We report measurements of the low field structure of the magnetic vortex
lattice in an untwinned YBCO single-crystal platelet. Measurements were carried
out using a novel atomic beam magnetic resonance (ABMR) technique. For a 10.7 G
field applied parallel to the c-axis of the sample, we find a triangular
lattice with orientational order extending across the entire sample. We find
the triangular lattice to be weakly distorted by the a-b anisotropy of the
material and measure a distortion factor, f = 1.16. Model-experiment
comparisons determine a penetration depth, lambda_ab = 140 (+-20) nm. The paper
includes the first detailed description of the ABMR technique. We discuss both
technical details of the experiment and the modeling used to interpret the
measurements.Comment: 44 pages, 13 figures, submitted to Phys. Rev. B Revision includes
Postscript wrapped figures + minor typo
Targeted nasal vaccination provides antibody-independent protection against Staphylococcus aureus.
Despite showing promise in preclinical models, anti-Staphylococcus aureus vaccines have failed in clinical trials. To date, approaches have focused on neutralizing/opsonizing antibodies; however, vaccines exclusively inducing cellular immunity have not been studied to formally test whether a cellular-only response can protect against infection. We demonstrate that nasal vaccination with targeted nanoparticles loaded with Staphylococcus aureus antigen protects against acute systemic S. aureus infection in the absence of any antigen-specific antibodies. These findings can help inform future developments in staphylococcal vaccine development and studies into the requirements for protective immunity against S. aureus
Common and low frequency variants in MERTK are independently associated with multiple sclerosis susceptibility with discordant association dependent upon HLA-DRB1*15:01 status
Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. The risk of developing MS is strongly influenced by genetic predisposition, and over 100 loci have been established as associated with susceptibility. However, the biologically relevant variants underlying disease risk have not been defined for the vast majority of these loci, limiting the power of these genetic studies to define new avenues of research for the development of MS therapeutics. It is therefore crucial that candidate MS susceptibility loci are carefully investigated to identify the biological mechanism linking genetic polymorphism at a given gene to the increased chance of developing MS. MERTK has been established as an MS susceptibility gene and is part of a family of receptor tyrosine kinases known to be involved in the pathogenesis of demyelinating disease. In this study we have refined the association of MERTK with MS risk to independent signals from both common and low frequency variants. One of the associated variants was also found to be linked with increased expression of MERTK in monocytes and higher expression of MERTK was associated with either increased or decreased risk of developing MS, dependent upon HLA-DRB1*15:01 status. This discordant association potentially extended beyond MS susceptibility to alterations in disease course in established MS. This study provides clear evidence that distinct polymorphisms within MERTK are associated with MS susceptibility, one of which has the potential to alter MERTK transcription, which in turn can alter both susceptibility and disease course in MS patients
R-parity preserving super-WIMP decays
We point out that when the decay of one electroweak scale super-WIMP state to
another occurs at second order in a super-weak coupling constant, this can
naturally lead to decay lifetimes that are much larger than the age of the
Universe, and create observable consequences for the indirect detection of dark
matter. We demonstrate this in a supersymmetric model with Dirac neutrinos,
where the right-handed scalar neutrinos are the lightest and next-to-lightest
supersymmetric partners. We show that this model produces a super-WIMP decay
rate scaling as m_nu^4/(weak scale)^3, and may significantly enhance the
fraction of energetic electrons and positrons over anti-protons in the decay
products. Such a signature is consistent with the observations recently
reported by the PAMELA experiment.Comment: 14 pages, v3 JHEP versio
Supersymmetry with a Chargino NLSP and Gravitino LSP
We demonstrate that the lightest chargino can be lighter than the lightest
neutralino in supersymmetric models with Dirac gaugino masses as well as within
a curious parameter region of the MSSM. Given also a light gravitino, such as
from low scale supersymmetry breaking, this mass hierarchy leads to an unusual
signal where every superpartner cascades down to a chargino that decays into an
on-shell W and a gravitino, possibly with a macroscopic chargino track. We
clearly identify the region of parameters where this signal can occur. We find
it is generic in the context of the R-symmetric supersymmetric standard model,
whereas it essentially only occurs in the MSSM when sign(M1) is not equal to
sign(M2) = sign(\mu) and tan(beta) is small. We briefly comment on the search
strategies for this signal at the LHC.Comment: 27 pages and 16 figure
Two component dark matter
We explain the PAMELA positron excess and the PPB-BETS/ATIC e+ + e- data
using a simple two component dark matter model (2DM). The two particle species
in the dark matter sector are assumed to be in thermal equilibrium in the early
universe. While one particle is stable and is the present day dark matter, the
second one is metastable and decays after the universe is 10^-8 s old. In this
model it is simple to accommodate the large boost factors required to explain
the PAMELA positron excess without the need for large spikes in the local dark
matter density. We provide the constraints on the parameters of the model and
comment on possible signals at future colliders.Comment: 6 pages, 2 figures, discussion clarified and extende
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