463 research outputs found
Generalized Classical BRST Cohomology and Reduction of Poisson Manifolds
In this paper, we formulate a generalization of the classical BRST
construction which applies to the case of the reduction of a poisson manifold
by a submanifold. In the case of symplectic reduction, our procedure
generalizes the usual classical BRST construction which only applies to
symplectic reduction of a symplectic manifold by a coisotropic submanifold,
\ie\ the case of reducible ``first class'' constraints. In particular, our
procedure yields a method to deal with ``second-class'' constraints. We
construct the BRST complex and compute its cohomology. BRST cohomology vanishes
for negative dimension and is isomorphic as a poisson algebra to the algebra of
smooth functions on the reduced poisson manifold in zero dimension. We then
show that in the general case of reduction of poisson manifolds, BRST
cohomology cannot be identified with the cohomology of vertical differential
forms.Comment: 3
Imaging of Low Compressibility Strips in the Quantum Hall Liquid
Using Subsurface Charge Accumulation scanning microscopy we image strips of
low compressibility corresponding to several integer Quantum Hall filling
factors. We study in detail the strips at Landau level filling factors
2 and 4. The observed strips appear significantly wider than predicted by
theory. We present a model accounting for the discrepancy by considering a
disorder-induced nonzero density of states in the cyclotron gap.Comment: 5 pages, 3 figure
The closest elastic tensor of arbitrary symmetry to an elasticity tensor of lower symmetry
The closest tensors of higher symmetry classes are derived in explicit form
for a given elasticity tensor of arbitrary symmetry. The mathematical problem
is to minimize the elastic length or distance between the given tensor and the
closest elasticity tensor of the specified symmetry. Solutions are presented
for three distance functions, with particular attention to the Riemannian and
log-Euclidean distances. These yield solutions that are invariant under
inversion, i.e., the same whether elastic stiffness or compliance are
considered. The Frobenius distance function, which corresponds to common
notions of Euclidean length, is not invariant although it is simple to apply
using projection operators. A complete description of the Euclidean projection
method is presented. The three metrics are considered at a level of detail far
greater than heretofore, as we develop the general framework to best fit a
given set of moduli onto higher elastic symmetries. The procedures for finding
the closest elasticity tensor are illustrated by application to a set of 21
moduli with no underlying symmetry.Comment: 48 pages, 1 figur
Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils
The development of BiPo detectors is dedicated to the measurement of
extremely high radiopurity in Tl and Bi for the SuperNEMO
double beta decay source foils. A modular prototype, called BiPo-1, with 0.8
of sensitive surface area, has been running in the Modane Underground
Laboratory since February, 2008. The goal of BiPo-1 is to measure the different
components of the background and in particular the surface radiopurity of the
plastic scintillators that make up the detector. The first phase of data
collection has been dedicated to the measurement of the radiopurity in
Tl. After more than one year of background measurement, a surface
activity of the scintillators of (Tl) 1.5
Bq/m is reported here. Given this level of background, a larger BiPo
detector having 12 m of active surface area, is able to qualify the
radiopurity of the SuperNEMO selenium double beta decay foils with the required
sensitivity of (Tl) 2 Bq/kg (90% C.L.) with a six
month measurement.Comment: 24 pages, submitted to N.I.M.
Spectral modeling of scintillator for the NEMO-3 and SuperNEMO detectors
We have constructed a GEANT4-based detailed software model of photon
transport in plastic scintillator blocks and have used it to study the NEMO-3
and SuperNEMO calorimeters employed in experiments designed to search for
neutrinoless double beta decay. We compare our simulations to measurements
using conversion electrons from a calibration source of and show
that the agreement is improved if wavelength-dependent properties of the
calorimeter are taken into account. In this article, we briefly describe our
modeling approach and results of our studies.Comment: 16 pages, 10 figure
Physiotherapy interventions for people with dementia and a hip fracture-a scoping review of the literature.
BACKGROUND: People with dementia are 2.7 times more likely to suffer a hip fracture than those without and their management is estimated to cost £0.92 billion per year. Yet there has been little focus on the effectiveness of interventions for this population. OBJECTIVE: The aim of this scoping review was to summarise the current available evidence for physiotherapy interventions for people with dementia who fracture their hip as well as to identify gaps in the literature that may require further research. DATA SOURCES: A systematic search of the following databases was undertaken-TRIP, CINAHL, Amed, Embase, PEDro, PsycINFO, Cochrane Library, Open Grey, Ethos, ISRCTN, Proquest, PROSPERO and UK Clinical Trials Gateway. STUDY SELECTION: Articles were included if they described an intervention which is considered within the scope of a physiotherapist and targeted those with both a hip fracture and dementia. SYNTHESIS METHODS: A narrative summary was then undertaken to describe the current state of the literature. RESULTS: Twenty six studies were included, of which thirteen were observational, six RCTs, two qualitative, two surveys and three systematic reviews. Only nine studies focused explicitly on physiotherapy interventions. CONCLUSION: The findings of this scoping review suggest there is limited evidence to guide physiotherapists in the management of people with dementia who fracture their hip. No evidence was found about perceptions or experiences of patients in this group or of the physiotherapists involved in their care. Further research is needed to develop and evaluate physiotherapy interventions for people with dementia who fracture their hip
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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