27,169 research outputs found
Sparticle Production in Electron-Photon Collisions
We explore the potential of electron-photon colliders to measure fundamental
supersymmetry parameters via the processes
(selectron-neutralino) and
(sneutrino-chargino). Given the and masses from
and hadron collider studies, cross section ratios
for opposite photon helicities determine
the , and masses, independent of the
sparticle branching fractions. The difference measures in a model-independent way. The
and masses test the universality of soft supersymmetry breaking
scalar masses. The cross section normalizations provide information about the
gaugino mixing parameters.Comment: add refs; add \tightenline
Band gaps in pseudopotential self-consistent GW calculations
For materials which are incorrectly predicted by density functional theory to
be metallic, an iterative procedure must be adopted in order to perform GW
calculations. In this paper we test two iterative schemes based on the
quasi-particle and pseudopotential approximations for a number of inorganic
semiconductors whose electronic structures are well known from experiment.
Iterating just the quasi-particle energies yields a systematic, but modest
overestimate of the band gaps, confirming conclusions drawn earlier for CaB_6
and YH_3. Iterating the quasi-particle wave functions as well gives rise to an
imbalance between the Hartree and Fock potentials and results in bandgaps in
far poorer agreement with experiment.Comment: 5 pages, 2 figures, 2 table
Electronic structure induced reconstruction and magnetic ordering at the LaAlOSrTiO interface
Using local density approximation (LDA) calculations we predict
GdFeO-like rotation of TiO octahedra at the -type interface between
LaAlO and SrTiO. The narrowing of the Ti bandwidth which results
means that for very modest values of , LDA calculations predict charge
and spin ordering at the interface. Recent experimental evidence for magnetic
interface ordering may be understood in terms of the close proximity of an
antiferromagnetic insulating ground state to a ferromagnetic metallic excited
state
Test of Fermi Gas Model and Plane-Wave Impulse Approximation Against Electron-Nucleus Scattering Data
A widely used relativistic Fermi gas model and plane-wave impulse
approximation are tested against electron-nucleus scattering data. Inclusive
quasi-elastic cross section are calculated and compared with high-precision
data for C, O, and Ca. A dependence of agreement between calculated cross
section and data on a momentum transfer is shown. Results for the C(nu_mu,mu)
reaction are presented and compared with experimental data of the LSND
collaboration.Comment: 10 pages, 8 figure
Physics with Beam Tau-Neutrino Appearance at DUNE
We explore the capabilities of the upcoming Deep Underground Neutrino
Experiment (DUNE) to measure charged-current interactions and the
associated oscillation probability at its far
detector, concentrating on how such results can be used to probe neutrino
properties and interactions. DUNE has the potential to identify significantly
more events than all existing experiments and can use this data
sample to nontrivially test the three-massive-neutrinos paradigm by providing
complementary measurements to those from the appearance and
disappearance channels. We further discuss the sensitivity of the
appearance channel to several hypotheses for the physics that may lurk beyond
the three-massive-neutrinos paradigm: a non-unitary lepton mixing matrix, the
light neutrinos hypothesis, and the existence of non-standard
neutral-current neutrino interactions. Throughout, we also consider the
relative benefits of the proposed high-energy tune of the Long-Baseline
Neutrino Facility (LBNF) beam-line.Comment: 23 pages, 14 figures, 2 appendice
Quasi-elastic neutrino charged-current scattering cross sections on oxygen
The charged-current quasi-elastic scattering of muon neutrinos on oxygen
target is computed for neutrino energies between 200 MeV and 2.5 GeV using the
relativistic distorted-wave impulse approximation with relativistic optical
potential, which was earlier successfully applied to describe electron-nucleus
data. We study both neutrino and electron processes and show that the reduced
exclusive cross sections for neutrino and electron scattering are similar. The
comparison with the relativistic Fermi gas model (RFGM), which is widely used
in data analyses of neutrino experiments, shows that the RFGM fails completely
when applied to exclusive cross section data and leads to overestimated values
of inclusive and total cross sections. We also found significant nuclear-model
dependence of exclusive, inclusive and total cross sections for about 1 GeV
energy.Comment: 30 pages, 11 figures; final version to appear in Phys. Rev.
Isolation & Characterization of Bacteria in the Built Environment: Measuring The Effect of Pharmaceuticals on Growth
This work reports the isolation and characterization of bacteria from the built environment at Gettysburg College in Gettysburg, PA. Surfaces of a water fountain on campus were swabbed and serially streaked to isolate multiple bacteria on R2A agar. Following multiple rounds of growth, the unknown microbial candidates were narrowed to two visiblydistinct organisms. Morphological characterization and phylogenetic identification based on 16S rDNA sequencing revealed that the isolates were Chryseobactierum hispalense and Microbacterium maritypicum. We report synergistic biofilm formation between Chryseobactierum hispalense and Microbacterium maritypicum. The contamination of drinking water with varying levels of personal care products and pharmaceuticals (PCPPs) is well documented. Additionally, these environmental pollutants and their derivatives affect aquatic life, as illustrated with effect of the antidepressant fluoxetine on mudsnails. To determine if previously reported contaminants affect freshwater bacteria, we assessed both planktonic growth and biofilm formation following exposure to nalidixic acid (nonfluorinated quinolone antibiotic), diphenhydramine (overthecounter drug Benadryl), and fluoxetine (Prozac)
The educational turn in art: rewriting the hidden curriculum
Around 2006, the art world developed a prolonged fascination with questions of education, pedagogy and the art school. ‘The Educational Turn’ (Rogoff, 2008) as it became known, produced a plethora of artistic and curatorial practices that engage with educational paradigms and problematics. Prompted in part by the European Union Bologna Process, the Educational Turn provided a critique of education as one-directional knowledge transfer, and the framing of education as a commercialised industry, reduced to the utilitarianism of training for working life. At the same time, it established ‘education’ as a thematic for the art world, in most cases divorced from its capacity for producing change in the fields of art or education. This article asks, what is the hidden curriculum (Illich) of this Educational Turn? Drawing from the writings of Colin Crouch, Wolfgang Streeck and Paulo Virno among others, it suggests that such ‘turns’ without a vital link to the realm of action, contribute to the broader problematic of public programming without a public sphere, through which formerly democratic institutions (like art galleries) operate as shells in a capitalist environment that is increasingly incompatible with democracy. We read The Education Turn here as a missed opportunity to re-shape art curricula and institutions, to develop a movement to oppose the Bologna Accord and the brutal changes imposed on art education through austerity politics. Finally, we argue - citing the writings of Paulo Friere, the mutualist movements in Europe of the 18th and 19th centuries, the educational experiments of Celestin Freinet in and Fernand Oury in France in the 1950s and the pedagogies of feminist and post-colonial struggle - for a deeper connection to radical education genealogies and their contemporary counterparts in contemporary public programming today
Interface resistance of disordered magnetic multilayers
We study the effect of interface disorder on the spin-dependent interface
resistances of Co/Cu, Fe/Cr and Au/Ag multilayers using a newly developed
method for calculating transmission matrices from first-principles. The
efficient implementation using tight-binding linear-muffin-tin orbitals allows
us to model interface disorder using large lateral supercells whereby specular
and diffuse scattering are treated on an equal footing. Without introducing any
free parameters, quantitative agreement with experiment is obtained. We predict
that disorder {\it reduces} the majority-spin interface resistance of
Fe/Cr(100) multilayers by a factor 3.Comment: 5 pages, 2 figures, submitted to PR
Fruit-Derived Polyphenol Supplementation for Athlete Recovery and Performance
This is the final version. Available from Springer Verlag via the DOI in this record.Polyphenols are characterised structurally by two or more hydroxyl groups attached to one or more benzene rings, and provide the taste and colour characteristics of fruits and vegetables. They are radical scavengers and metal chelators, but due to their low concentration in biological fluids in vivo their antioxidant properties seem to be related to enhanced endogenous antioxidant capacity induced via signalling through the Nrf2 pathway. Polyphenols also seem to possess anti-inflammatory properties and have been shown to enhance vascular function via nitric oxide-mediated mechanisms. As a consequence, there is a rationale for supplementation with fruit-derived polyphenols both to enhance exercise performance, since excess reactive oxygen species generation has been implicated in fatigue development, and to enhance recovery from muscle damage induced by intensive exercise due to the involvement of inflammation and oxidative damage within muscle. Current evidence would suggest that acute supplementation with ~ 300 mg polyphenols 1–2 h prior to exercise may enhance exercise capacity and/or performance during endurance and repeated sprint exercise via antioxidant and vascular mechanisms. However, only a small number of studies have been performed to date, some with methodological limitations, and more research is needed to confirm these findings. A larger body of evidence suggests that supplementation with > 1000 mg polyphenols per day for 3 or more days prior to and following exercise will enhance recovery following muscle damage via antioxidant and anti-inflammatory mechanisms. The many remaining unanswered questions within the field of polyphenol research and exercise performance and recovery are highlighted within this review article.Gatorade Sports Science Institute (GSSI
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