10,317 research outputs found
Codimension zero superembeddings
Superembeddings which have bosonic codimension zero are studied in 3,4 and 6
dimensions. The worldvolume multiplets of these branes are off-shell vector
multiplets in these dimensions, and their self-interactions include a
Born-Infeld term. It is shown how they can be written in terms of standard
vector multiplets in flat superspace by working in the static gauge. The action
formula is used to determine both Green-Schwarz type actions and superfield
actions.Comment: Improved spelling, one reference adde
Health care resouce use and stroke outcome
Background and Purpose: Outcome in patients hospitalized for acute stroke varies considerably between populations. Within the framework of the GAIN International trial, a large multicenter trial of a neuroprotective agent (gavestinel, glycine antagonist), stroke outcome in relation to health care resource use has been compared in a large number of countries, allowing for differences in case mix. Methods: This substudy includes 1,422 patients in 19 countries grouped into 10 regions. Data on prognostic variables on admission to hospital, resource use, and outcome were analyzed by regression models. Results: All results were adjusted for differences in prognostic factors on admission (NIH Stroke Scale, age, comorbidity). There were threefold variations in the average number of days in hospital/institutional care (from 20 to 60 days). The proportion of patients who met with professional rehabilitation staff also varied greatly. Three-month case fatality ranged from 11% to 28%, and mean Barthel ADL score at three months varied between 64 and 73. There was no relationship between health care resource use and outcome in terms of survival and ADL function at three months. The proportion of patients living at home at three months did not show any relationship to ADL function across countries. Conclusions: There are wide variations in health care resource use between countries, unexplained by differences in case mix. Across countries, there is no obvious relationship between resource use and clinical outcome after stroke. Differences in health care traditions (treatment pathways) and social We thank the coinvestigators and research staff at the participating centers for their support. Glaxo Wellcome sponsored the GAIN International trial, supported the present analyses and reviewed the final draft of the article
A new dawn? The Roman Catholic Church and environmental issues
This is a PDF version of an article published in New Blackfriars© 1997. The definitive version is available at www.blackwell-synergy.com.This article discusses the stance of the Roman Catholic Church on environmental issues and argues that the Church tends to stay on the fringe rather than get involved. Some of the ways in which Roman Catholic theologians have incorporated environmental issues into theological reflection is discussed, as are environmental challenges facing the Church in Britain (conservation, resources, biodiversity, animal welfare, biotechnology, cooperate/individual ethics, environmental justice, economics/policy development, and global issues)
Relating Superembeddings and Non-linear Realisations
We discuss the relation between the superembedding method for deriving
worldvolume actions for D-branes and the method of Partially Broken Global
Supersymmetry based upon linear and non-linear realisations of SUSY. We give
the explicit relation for the cases of space filling branes in 3 and 4
dimensions and show that the standard F-constraint of the superembedding method
is the source of the required covariant non-linear constraints for the PBGS
method.Comment: 19 pages. Improved spelling, references adde
The supermembrane revisited
The M2-brane is studied from the perspective of superembeddings. We review
the derivation of the M2-brane dynamics and the supergravity constraints from
the standard superembedding constraint and we discuss explicitly the induced
d=3, N=8 superconformal geometry on the worldvolume. We show that the gauged
supermembrane, for a target space with a U(1) isometry, is the standard
D2-brane in a type IIA supergravity background. In particular, the D2-brane
action, complete with the Dirac-Born-Infeld term, arises from the gauged
Wess-Zumino worldvolume 4-form via the brane action principle. The discussion
is extended to the massive D2-brane considered as a gauged supermembrane in a
massive D=11 superspace background. Type IIA supergeometry is derived using
Kaluza-Klein techniques in superspace.Comment: Latex, 46 pages, clarifying remarks and references adde
Kappa-symmetric deformations of M5-brane dynamics
We calculate the first supersymmetric and kappa-symmetric derivative
deformation of the M5-brane worldvolume theory in a flat eleven-dimensional
background. By applying cohomological techniques we obtain a deformation of the
standard constraint of the superembedding formalism. The first possible
deformation of the constraint and hence the equations of motion arises at cubic
order in fields and fourth order in a fundamental length scale . The
deformation is unique up to this order. In particular this rules out any
induced Einstein-Hilbert terms on the worldvolume. We explicitly calculate
corrections to the equations of motion for the tensor gauge supermultiplet.Comment: 17 pages. Additional comments in section
Effective diffusion constant in a two dimensional medium of charged point scatterers
We obtain exact results for the effective diffusion constant of a two
dimensional Langevin tracer particle in the force field generated by charged
point scatterers with quenched positions. We show that if the point scatterers
have a screened Coulomb (Yukawa) potential and are uniformly and independently
distributed then the effective diffusion constant obeys the
Volgel-Fulcher-Tammann law where it vanishes. Exact results are also obtained
for pure Coulomb scatterers frozen in an equilibrium configuration of the same
temperature as that of the tracer.Comment: 9 pages IOP LaTex, no figure
Theory of Microwave Parametric Down Conversion and Squeezing Using Circuit QED
We study theoretically the parametric down conversion and squeezing of
microwaves using cavity quantum electrodynamics of a superconducting Cooper
pair box (CPB) qubit located inside a transmission line resonator. The
non-linear susceptibility \chi_2 describing three-wave mixing can be tuned by
dc gate voltage applied to the CPB and vanishes by symmetry at the charge
degeneracy point. We show that the coherent coupling of different cavity modes
through the qubit can generate a squeezed state. Based on parameters realized
in recent successful circuit QED experiments, squeezing of 95% ~ 13dB below the
vacuum noise level should be readily achievable.Comment: 4 pages, accepted for publication in Phys. Rev. Let
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