8,054 research outputs found
Using Evidence in the development of local health policies : Some Evidence from the United Kingdom
Objectives: This paper explores the use of evidence, focusing on economic evidence in particular, in the development of local health policies through an in-depth study of Health Improvement Programmes (HImPs) in England. Methods: A questionnaire was sent to the person responsible for coordinating the development of the HImP in each of the 102 English health authorities. In addition, semi-structured interviews were conducted with 10 HImP leaders, and a random sample of 26 HImP documents was reviewed using a standard pro forma. Results: Of the 102 mail questionnaires sent out, 68 (67%) were returned. It was found that those developing HImPs had multiple objectives, only some of which (e.g., efficiency in healthcare provision) would necessarily require evidence.Where evidence was used, this was a mixture of internal (experiential) and external (empirical) evidence, with the balance (66%) being in favor of the latter. Government reports and guidance from the National Institute for Clinical Excellence (NICE), were the main sources of external evidence, rather than published papers. Key barriers to the use of economic evidence were lack of time and availability and the difficulties in synthesizing information at the local level. Conclusions: Based on responses to our survey, the main ways of increasing the use of evidence in the development of local health policies in England are to produce more evidence-based national guidance and to produce accessible summaries of the available literature for local decision makers
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)
Einstein-Podolsky-Rosen correlations via dissociation of a molecular Bose-Einstein condensate
Recent experimental measurements of atomic intensity correlations through
atom shot noise suggest that atomic quadrature phase correlations may soon be
measured with a similar precision. We propose a test of local realism with
mesoscopic numbers of massive particles based on such measurements. Using
dissociation of a Bose-Einstein condensate of diatomic molecules into bosonic
atoms, we demonstrate that strongly entangled atomic beams may be produced
which possess Einstein-Podolsky-Rosen (EPR) correlations in field quadratures,
in direct analogy to the position and momentum correlations originally
considered by EPR.Comment: Final published version (corrections in Ref. [32], updated
references
Two-loop supergravity on AdSS from CFT
We describe a construction of the two-loop amplitude of four graviton
supermultiplets in AdSS. We start from an ansatz for a
preamplitude from which we generate the full amplitude under the action of a
specific Casimir operator. The ansatz captures a recent ansatz of Huang and
Yuan and we confirm their result through similar constraints. We identify a
class of four-dimensional `zigzag' integrals which are perfectly adapted to
describing the leading logarithmic discontinuity to all orders. We also observe
that a bonus crossing symmetry of the preamplitude follows from the
transformation properties of the Casimir operator. Combined with the zigzag
integrals this allows us to construct a crossing symmetric function with the
correct leading logarithmic discontinuities in all channels.
From the two-loop result we extract an explicit expression for the two-loop
correction to the anomalous dimensions of twist-four operators of generic spin
which includes dependence on (alternating) nested harmonic sums up to weight
three. We also revisit the prescription of the bulk-point limit of AdS
amplitudes and show how it recovers the full flat-space amplitude, not just its
discontinuity. With this extended notion of the bulk-point limit we reproduce
the scale-dependent logarithmic threshold terms of type IIB string theory in
flat-space.Comment: 51 pages, 1 ancillary fil
Quantum limits to center-of-mass measurements
We discuss the issue of measuring the mean position (center-of-mass) of a
group of bosonic or fermionic quantum particles, including particle number
fluctuations. We introduce a standard quantum limit for these measurements at
ultra-low temperatures, and discuss this limit in the context of both photons
and ultra-cold atoms. In the case of fermions, we present evidence that the
Pauli exclusion principle has a strongly beneficial effect, giving rise to a
1/N scaling in the position standard-deviation -- as opposed to a
scaling for bosons. The difference between the actual mean-position fluctuation
and this limit is evidence for quantum wave-packet spreading in the
center-of-mass. This macroscopic quantum effect cannot be readily observed for
non-interacting particles, due to classical pulse broadening. For this reason,
we also study the evolution of photonic and matter-wave solitons, where
classical dispersion is suppressed. In the photonic case, we show that the
intrinsic quantum diffusion of the mean position can contribute significantly
to uncertainties in soliton pulse arrival times. We also discuss ways in which
the relatively long lifetimes of attractive bosons in matter-wave solitons may
be used to demonstrate quantum interference between massive objects composed of
thousands of particles.Comment: 12 pages, 6 figures. Submitted to PRA. Revised to include more
references as well as a discussion of fermionic center-of-mas
Decoherence of Quantum-Enhanced Timing Accuracy
Quantum enhancement of optical pulse timing accuracy is investigated in the
Heisenberg picture. Effects of optical loss, group-velocity dispersion, and
Kerr nonlinearity on the position and momentum of an optical pulse are studied
via Heisenberg equations of motion. Using the developed formalism, the impact
of decoherence by optical loss on the use of adiabatic soliton control for
beating the timing standard quantum limit [Tsang, Phys. Rev. Lett. 97, 023902
(2006)] is analyzed theoretically and numerically. The analysis shows that an
appreciable enhancement can be achieved using current technology, despite an
increase in timing jitter mainly due to the Gordon-Haus effect. The decoherence
effect of optical loss on the transmission of quantum-enhanced timing
information is also studied, in order to identify situations in which the
enhancement is able to survive.Comment: 12 pages, 4 figures, submitte
Bootstrapping string theory on AdS
We make an ansatz for the Mellin representation of the four-point amplitude
of half-BPS operators of arbitrary charges at order in
an expansion around the supergravity limit. Crossing symmetry and a set of
constraints on the form of the spectrum uniquely fix the amplitude and
double-trace anomalous dimensions at this order. The results exhibit a number
of natural patterns which suggest that the bootstrap approach outlined here
will extend to higher orders in a simple way.Comment: 6 page
The Yangian origin of the Grassmannian integral
In this paper we analyse formulas which reproduce different contributions to
scattering amplitudes in N=4 super Yang-Mills theory through a Grassmannian
integral. Recently their Yangian invariance has been proved directly by using
the explicit expression of the Yangian level-one generators. The specific
cyclic structure of the form integrated over the Grassmannian enters in a
crucial way in demonstrating the symmetry. Here we show that the Yangian
symmetry fixes this structure uniquely.Comment: 26 pages. v2: typos corrected, published versio
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