3,056 research outputs found
Pruning and prioritising: a case study of a pragmatic method for managing a rapid systematic review with limited resources
Full systematic reviews are time and resource heavy. We describe a method successfully used to
produce a rapid review of yoga for health and wellbeing, with limited resources, using mapping
methods. Inclusion and exclusion criteria were developed a priori and refined post hoc, with the
review team blind to the study results to minimise the introduction of bias. This method allowed
the review to be tailored to make use of the best available evidence and the health topics of
most relevance to the commissioners, and to enable the evidence base to be disseminated to
practitioners in a timely fashion
Uniqueness and Non-uniqueness in the Einstein Constraints
The conformal thin sandwich (CTS) equations are a set of four of the Einstein
equations, which generalize the Laplace-Poisson equation of Newton's theory. We
examine numerically solutions of the CTS equations describing perturbed
Minkowski space, and find only one solution. However, we find {\em two}
distinct solutions, one even containing a black hole, when the lapse is
determined by a fifth elliptic equation through specification of the mean
curvature. While the relationship of the two systems and their solutions is a
fundamental property of general relativity, this fairly simple example of an
elliptic system with non-unique solutions is also of broader interest.Comment: 4 pages, 4 figures; abstract and introduction rewritte
Universal quantum gates based on a pair of orthogonal cyclic states: Application to NMR systems
We propose an experimentally feasible scheme to achieve quantum computation
based on a pair of orthogonal cyclic states. In this scheme, quantum gates can
be implemented based on the total phase accumulated in cyclic evolutions. In
particular, geometric quantum computation may be achieved by eliminating the
dynamic phase accumulated in the whole evolution. Therefore, both dynamic and
geometric operations for quantum computation are workable in the present
theory. Physical implementation of this set of gates is designed for NMR
systems. Also interestingly, we show that a set of universal geometric quantum
gates in NMR systems may be realized in one cycle by simply choosing specific
parameters of the external rotating magnetic fields. In addition, we
demonstrate explicitly a multiloop method to remove the dynamic phase in
geometric quantum gates. Our results may provide useful information for the
experimental implementation of quantum logical gates.Comment: 9 pages, language revised, the publication versio
Clarifying Some Remaining Questions in the Anomaly Puzzle
We discuss several points that may help to clarify some questions that remain
about the anomaly puzzle in supersymmetric theories. In particular, we consider
a general N=1 supersymmetric Yang-Mills theory. The anomaly puzzle concerns the
question of whether there is a consistent way to put the R-current and the
stress tensor in a single supercurrent, even though in the classical theory
they are in the same supermultiplet. As is well known, the classically
conserved supercurrent bifurcates into two supercurrents having different
anomalies in the quantum regime. The most interesting result we obtain is an
explicit expression for the lowest component of one of the two supercurrents in
4-dimensional spacetime, namely the supercurrent that has the energy-momentum
tensor as one of its components. This expression for the lowest component is an
energy-dependent linear combination of two chiral currents, which itself does
not correspond to a classically conserved chiral current. The lowest component
of the other supercurrent, namely, the R-current, satisfies the Adler-Bardeen
theorem. The lowest component of the first supercurrent has an anomaly that we
show is consistent with the anomaly of the trace of the energy-momentum tensor.
Therefore, we conclude that there is no consistent way to put the R-current and
the stress tensor in a single supercurrent in the quantized theory. We also
discuss and try to clarify some technical points in the derivations of the
two-supercurrents in the literature. These latter points concern the
significance of infrared contributions to the NSVZ beta-function and the role
of the equations of motion in deriving the two supercurrents.Comment: 22 pages, no figure. v2: minor changes. v3: sections re-organized.
new subsections (IVA, IVB) added. references adde
OC-0257: NTCP models for acute dysphagia resulting from (chemo)radiotherapy for head and neck cancer
In search of hair damage using metabolomics?
YesHair fibres are extraordinary materials, not least because they are exquisitely formed by each of the 5 million or so hair follicles on our bodies and have functions that cross from physiology to psychology, but also because they have well known resistance to degradation as seen in hair surviving from archaeological and historical samples [1]. Hair fibres on the head grow at around 1cm each month, together totalling approximately 12km of growth per person per year. Each fibre is incredibly strong for its small diameter; with one fibre typically holding 100g and together a well-formed ponytail [allegedly] has the collective strength to support the weight of a small elephant! Hair – and from here I mean scalp hair – is under constant scrutiny by each of us; whether it be style, split ends, the first few grey hairs or the collection of hairs in the shower that should be firmly attached - leading to the fear that is hair loss
Implementation of a Deutsch-like quantum algorithm utilizing entanglement at the two-qubit level, on an NMR quantum information processor
We describe the experimental implementation of a recently proposed quantum
algorithm involving quantum entanglement at the level of two qubits using NMR.
The algorithm solves a generalisation of the Deutsch problem and distinguishes
between even and odd functions using fewer function calls than is possible
classically. The manipulation of entangled states of the two qubits is
essential here, unlike the Deutsch-Jozsa algorithm and the Grover's search
algorithm for two bits.Comment: 4 pages, two eps figure
PT-Symmetry Quantum Electrodynamics--PTQED
The construction of -symmetric quantum electrodynamics is
reviewed. In particular, the massless version of the theory in 1+1 dimensions
(the Schwinger model) is solved. Difficulties with unitarity of the -matrix
are discussed.Comment: 11 pages, 1 figure, contributed to Proceedings of 6th International
Workshop on Pseudo-Hermitian Hamiltonians in Quantum Physic
Spectral flow and boundary string field theory for angled D-branes
D-branes intersecting at an arbitrary fixed angle generically constitute a
configuration unstable toward recombination. The reconnection of the branes
nucleates at the intersection point and involves a generalization of the
process of brane decay of interest to non-perturbative string dynamics as well
as cosmology. After reviewing the string spectrum of systems of angled branes,
we show that worldsheet twist superfields may be used in the context of
Boundary Superstring Field Theory to describe the dynamics. Changing the angle
between the branes is seen from the worldsheet as spectral flow with boundary
insertions flowing from bosonic to fermionic operators. We calculate the
complete tachyon potential and the low energy effective action as a function of
angle and find an expression that interpolates between the brane-antibrane and
the Dirac-Born-Infeld actions. The potential captures the mechanism of D-brane
recombination and provides for interesting new physics for tachyon decay.Comment: 32 pages, 9 figures; v2 references added; v3 discussion clarifie
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