1,489 research outputs found
What do adolescents with asthma really think about adherence to inhalers? Insights from a qualitative analysis of a UK online forum
ADS is funded by an NIHR Academic Clinical Lectureship. AB is an NIHR
Senior Investigator and additionally was supported by the NIHR Respiratory Disease.
RH was supported by the National Institute for Health Research (NIHR) Collaboration
for Leadership in Applied Health Research (CLAHRC) North Thames at Barts NHS
Trust. The views expressed are those of the author(s) and not necessarily those of
the NHS, NIHR or Department of Health
From the WZWN Model to the Liouville Equation: Exact String Dynamics in Conformally Invariant AdS Background
It has been known for some time that the SL(2,R) WZWN model reduces to
Liouville theory. Here we give a direct and physical derivation of this result
based on the classical string equations of motion and the proper string size.
This allows us to extract precisely the physical effects of the metric and
antisymmetric tensor, respectively, on the {\it exact} string dynamics in the
SL(2,R) background. The general solution to the proper string size is also
found. We show that the antisymmetric tensor (corresponding to conformal
invariance) generally gives rise to repulsion, and it precisely cancels the
dominant attractive term arising from the metric.
Both the sinh-Gordon and the cosh-Gordon sectors of the string dynamics in
non-conformally invariant AdS spacetime reduce here to the Liouville equation
(with different signs of the potential), while the original Liouville sector
reduces to the free wave equation. Only the very large classical string size is
affected by the torsion. Medium and small size string behaviours are unchanged.
We also find illustrative classes of string solutions in the SL(2,R)
background: dynamical closed as well as stationary open spiralling strings, for
which the effect of torsion is somewhat like the effect of rotation in the
metric. Similarly, the string solutions in the 2+1 BH-AdS background with
torsion and angular momentum are fully analyzed.Comment: 24 pages including 4 postscript figures. Enlarged version including a
section on string solutions in 2+1 black hole background. To be published in
Phys. Rev. D., December 199
Electronic reminders and rewards to improve adherence to inhaled asthma treatment in adolescents: a non-randomised feasibility study in tertiary care
OBJECTIVE: To test the feasibility and acceptability of a short-term reminder and incentives intervention in adolescents with low adherence to asthma medications. METHODS: Mixed-methods feasibility study in a tertiary care clinic. Adolescents recruited to a 24-week programme with three 8-weekly visits, receiving electronic reminders to prompt inhaled corticosteroid (ICS) inhalation through a mobile app coupled with electronic monitoring devices (EMD). From the second visit, monetary incentives based on adherence of ICS inhalation: £1 per dose, maximum £2 /day, up to £112/study, collected as gift cards at the third visit. End of study interviews and questionnaires assessing perceptions of asthma and ICS, analysed using the Perceptions and Practicalities Framework. PARTICIPANTS: Adolescents (11-18 years) with documented low ICS adherence (<80% by EMD), and poor asthma control at the first clinic visit. RESULTS: 10 out of 12 adolescents approached were recruited (7 males, 3 females, 12-16 years). Eight participants provided adherence measures up to the fourth visits and received rewards. Mean study duration was 281 days, with 7/10 participants unable to attend their fourth visit due to COVID-19 lockdown. Only 3/10 participants managed to pair the app/EMD up to the fourth visit, which was associated with improved ICS adherence (from 0.51, SD 0.07 to 0.86, SD 0.05). Adherence did not change in adolescents unable to pair the app/EMD. The intervention was acceptable to participants and parents/guardians. Exit interviews showed that participants welcomed reminders and incentives, though expressed frustration with app/EMD technological difficulties. Participants stated the intervention helped through reminding ICS doses, promoting self-monitoring and increasing motivation to take inhalers. CONCLUSIONS: An intervention using electronic reminders and incentives through an app coupled with an EMD was feasible and acceptable to adolescents with asthma. A pilot randomised controlled trial is warranted to better estimate the effect size on adherence, with improved technical support for the EMD
Observables in Topological Yang-Mills Theories
Using topological Yang-Mills theory as example, we discuss the definition and
determination of observables in topological field theories (of Witten-type)
within the superspace formulation proposed by Horne. This approach to the
equivariant cohomology leads to a set of bi-descent equations involving the
BRST and supersymmetry operators as well as the exterior derivative. This
allows us to determine superspace expressions for all observables, and thereby
to recover the Donaldson-Witten polynomials when choosing a Wess-Zumino-type
gauge.Comment: 39 pages, Late
Electronic reminders and rewards to improve adherence to inhaled asthma treatment in adolescents:a non-randomised feasibility study in tertiary care
OBJECTIVE: To test the feasibility and acceptability of a short-term reminder and incentives intervention in adolescents with low adherence to asthma medications. METHODS: Mixed-methods feasibility study in a tertiary care clinic. Adolescents recruited to a 24-week programme with three 8-weekly visits, receiving electronic reminders to prompt inhaled corticosteroid (ICS) inhalation through a mobile app coupled with electronic monitoring devices (EMD). From the second visit, monetary incentives based on adherence of ICS inhalation: £1 per dose, maximum £2 /day, up to £112/study, collected as gift cards at the third visit. End of study interviews and questionnaires assessing perceptions of asthma and ICS, analysed using the Perceptions and Practicalities Framework. PARTICIPANTS: Adolescents (11-18 years) with documented low ICS adherence (<80% by EMD), and poor asthma control at the first clinic visit. RESULTS: 10 out of 12 adolescents approached were recruited (7 males, 3 females, 12-16 years). Eight participants provided adherence measures up to the fourth visits and received rewards. Mean study duration was 281 days, with 7/10 participants unable to attend their fourth visit due to COVID-19 lockdown. Only 3/10 participants managed to pair the app/EMD up to the fourth visit, which was associated with improved ICS adherence (from 0.51, SD 0.07 to 0.86, SD 0.05). Adherence did not change in adolescents unable to pair the app/EMD. The intervention was acceptable to participants and parents/guardians. Exit interviews showed that participants welcomed reminders and incentives, though expressed frustration with app/EMD technological difficulties. Participants stated the intervention helped through reminding ICS doses, promoting self-monitoring and increasing motivation to take inhalers. CONCLUSIONS: An intervention using electronic reminders and incentives through an app coupled with an EMD was feasible and acceptable to adolescents with asthma. A pilot randomised controlled trial is warranted to better estimate the effect size on adherence, with improved technical support for the EMD
A new mass-ratio for the X-ray Binary X2127+119 in M15?
The luminous low-mass X-ray binary X2127+119 in the core of the globular
cluster M15 (NGC 7078), which has an orbital period of 17 hours, has long been
assumed to contain a donor star evolving off the main sequence, with a mass of
0.8 solar masses (the main-sequence turn-off mass for M15). We present
orbital-phase-resolved spectroscopy of X2127+119 in the H-alpha and He I 6678
spectral region, obtained with the Hubble Space Telescope. We show that these
data are incompatible with the assumed masses of X2127+119's component stars.
The continuum eclipse is too shallow, indicating that much of the accretion
disc remains visible during eclipse, and therefore that the size of the donor
star relative to the disc is much smaller in this high-inclination system than
the assumed mass-ratio allows. Furthermore, the flux of X2127+119's He I 6678
emission, which has a velocity that implies an association with the stream-disc
impact region, remains unchanged through eclipse, implying that material from
the impact region is always visible. This should not be possible if the
previously-assumed mass ratio is correct. In addition, we do not detect any
spectral features from the donor star, which is unexpected for a 0.8 solar-mass
sub-giant in a system with a 17-hour period.Comment: 6 pages, 4 figures, accepted by A&
Quantum String Dynamics in the conformal invariant SL(2,R) WZWN Background: Anti-de Sitter Space with Torsion
We consider classical and quantum strings in the conformally invariant
background corresponding to the SL(2,R) WZWN model. This background is locally
anti-de Sitter spacetime with non-vanishing torsion. Conformal invariance is
expressed as the torsion being parallelized. The precise effect of the
conformal invariance on the dynamics of both circular and generic classical
strings is extracted. In particular, the conformal invariance gives rise to a
repulsive interaction of the string with the background which precisely cancels
the dominant attractive term arising from gravity. We perform both
semi-classical and canonical string-quantization, in order to see the effect of
the conformal invariance of the background on the string mass spectrum. Both
approaches yield that the high-mass states are governed by m sim HN (N,`large
integer'), where m is the string mass and H is the Hubble constant. It follows
that the level spacing grows proportionally to N: d(m^2 alpha')/dN sim N, while
the entropy goes like: S sim sqrt{m}. Moreover, it follows that there is no
Hagedorn temperature,so that the partition function is well defined at any
positive temperature. All results are compared with the analogue results in
Anti- de Sitter spacetime, which is a non conformal invariant background.
Conformal invariance simplifies the mathematics of the problem but the physics
remains mainly unchanged. Differences between conformal and non-conformal
backgrounds only appear in the intermediate region of the string spectrum, but
these differences are minor. For low and high masses, the string mass spectra
in conformal and non-conformal backgrounds are identical. Interestingly enough,
conformal invariance fixes the value of the spacetime curvature to be -69/(26
alpha').Comment: Latex file, 23 pages, no figure
Strings in Cosmological and Black Hole Backgrounds: Ring Solutions
The string equations of motion and constraints are solved for a ring shaped
Ansatz in cosmological and black hole spacetimes. In FRW universes with
arbitrary power behavior [R(X^0) = a\;|X^0|^{\a}\, ], the asymptotic form of
the solution is found for both and and we plot the
numerical solution for all times. Right after the big bang (), the
string energy decreasess as and the string size grows as for . Very
soon [ ] , the ring reaches its oscillatory regime with frequency
equal to the winding and constant size and energy. This picture holds for all
values of \a including string vacua (for which, asymptotically, \a = 1).
In addition, an exact non-oscillatory ring solution is found. For black hole
spacetimes (Schwarzschild, Reissner-Nordstr\oo m and stringy), we solve for
ring strings moving towards the center. Depending on their initial conditions
(essentially the oscillation phase), they are are absorbed or not by
Schwarzschild black holes. The phenomenon of particle transmutation is
explicitly observed (for rings not swallowed by the hole). An effective horizon
is noticed for the rings. Exact and explicit ring solutions inside the
horizon(s) are found. They may be interpreted as strings propagating between
the different universes described by the full black hole manifold.Comment: Paris preprint PAR-LPTHE-93/43. Uses phyzzx. Includes figures. Text
and figures compressed using uufile
Control of quantum transverse correlations on a four-photon system
Control of spatial quantum correlations in bi-photons is one of the
fundamental principles of Quantum Imaging. Up to now, experiments have been
restricted to controlling the state of a single bi-photon, by using linear
optical elements. In this work we demonstrate experimental control of quantum
correlations in a four-photon state comprised of two pairs of photons. Our
scheme is based on a high-efficiency parametric downconversion source coupled
to a double slit by a variable linear optical setup, in order to obtain
spatially encoded qubits. Both entangled and separable pairs have been
obtained, by altering experimental parameters. We show how the correlations
influence both the interference and diffraction on the double slit.Comment: 14 pages, 6 figure
Dynamical mass of a star cluster in M83: a test of fibre-fed multi-object spectroscopy
(Abridged) Aims: We obtained VLT/FLAMES+UVES high-resolution, fibre-fed
spectroscopy (FFS) of five young massive clusters in M83 (NGC 5236). This forms
the basis of a pilot study testing the feasibility of using FFS to measure the
velocity dispersions of several clusters simultaneously, in order to determine
their dynamical masses; Methods: We adopted two methods for determining the
velocity dispersion of the star clusters: cross-correlating the cluster
spectrum with the template spectra and minimising a chi^2 value between the
cluster spectrum and the broadened template spectra. Cluster 805 in M83 was
chosen as a control to test the reliability of the method, through a comparison
with the results obtained from a standard echelle VLT/UVES spectrum obtained by
Larsen & Richtler; Results: We find no dependence of the velocity dispersions
measured for a cluster on the choice of red giant versus red supergiant
templates, nor on the method adopted. We measure a velocity dispersion of
sigma_los = 10.2+/-1.1 km/s for cluster 805 from our FFS. Our FLAMES+UVES
velocity dispersion measurement gives M_vir = (6.6+/-1.7)e5 M_sun, consistent
with previous results. This is a factor of ~3 greater than the cluster's
photometric mass, indicating a lack of virial equilibrium. However, based on
its effective star formation efficiency, the cluster is likely to virialise,
and may survive for a Hubble time, in the absence of external disruptive
forces; Conclusions: We find that reliable velocity dispersions can be
determined from FFS. The advantages of observing several clusters
simultaneously outweighs the difficulty of accurate galaxy background
subtraction, providing that the targets are chosen to provide sufficient S/N
ratios, and are much brighter than the galaxy background.Comment: 10 pages, 4 figures, accepted by A&
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