581 research outputs found
Benefits of Exercise in Rheumatoid Arthritis
This paper aims to highlight the importance of exercise in patients with rheumatoid arthritis (RA) and to demonstrate the multitude of beneficial effects that properly designed exercise training has in this population. RA is a chronic, systemic, autoimmune disease characterised by decrements to joint health including joint pain and inflammation, fatigue, increased incidence and progression of cardiovascular disease, and accelerated loss of muscle mass, that is, “rheumatoid cachexia”. These factors contribute to functional limitation, disability, comorbidities, and reduced quality of life. Exercise training for RA patients has been shown to be efficacious in reversing cachexia and substantially improving function without exacerbating disease activity and is likely to reduce cardiovascular risk. Thus, all RA patients should be encouraged to include aerobic and resistance exercise training as part of routine care. Understanding the perceptions of RA patients and health professionals to exercise is key to patients initiating and adhering to effective exercise training
The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102
The precise localization of the repeating fast radio burst (FRB 121102) has
provided the first unambiguous association (chance coincidence probability
) of an FRB with an optical and persistent radio
counterpart. We report on optical imaging and spectroscopy of the counterpart
and find that it is an extended ()
object displaying prominent Balmer and [OIII] emission lines. Based on the
spectrum and emission line ratios, we classify the counterpart as a
low-metallicity, star-forming, AB mag dwarf galaxy at a
redshift of , corresponding to a luminosity distance of 972 Mpc.
From the angular size, the redshift, and luminosity, we estimate the host
galaxy to have a diameter kpc and a stellar mass of
, assuming a mass-to-light ratio between 2 to
3. Based on the H flux, we estimate the star
formation rate of the host to be and a
substantial host dispersion measure depth .
The net dispersion measure contribution of the host galaxy to FRB 121102 is
likely to be lower than this value depending on geometrical factors. We show
that the persistent radio source at FRB 121102's location reported by Marcote
et al (2017) is offset from the galaxy's center of light by 200 mas and
the host galaxy does not show optical signatures for AGN activity. If FRB
121102 is typical of the wider FRB population and if future interferometric
localizations preferentially find them in dwarf galaxies with low metallicities
and prominent emission lines, they would share such a preference with long
gamma ray bursts and superluminous supernovae.Comment: 12 pages, 3 figures, Published in ApJ Letters. V2: Corrected mistake
in author lis
Reflecting the real value of health care resources in modelling and cost-effectiveness studies-The example of viral load informed differentiated care
BACKGROUND: The WHO HIV Treatment Guidelines suggest routine viral-load monitoring can be used to differentiate antiretroviral therapy (ART) delivery and reduce the frequency of clinic visits for patients stable on ART. This recommendation was informed by economic analysis that showed the approach is very likely to be cost-effective, even in the most resource constrained of settings. The health benefits were shown to be modest but the costs of introducing and scaling up viral load monitoring can be offset by anticipated reductions in the costs of clinic visits, due to these being less frequent for many patients. KEY ISSUES FOR ECONOMIC EVALUATION: The cost-effectiveness of introducing viral-load informed differentiated care depends upon whether cost reductions are possible if the number of clinic visits is reduced and/or how freed clinic capacity is used for alternative priorities. Where freed resources, either physical or financial, generate large health gains (e.g. if committed to patients failing ART or to other high value health care interventions), the benefits of differentiated care are expected to be high; if however these freed physical resources are already under-utilized or financial resources are used less efficiently and would not be put to as beneficial an alternative use, the policy may not be cost-effective. The implication is that the use of conventional unit costs to value resources may not well reflect the latter's value in contributing to health improvement. Analyses intended to inform resource allocated decisions in a number of settings may therefore have to be interpreted with due consideration to local context. In this paper we present methods of how economic analyses can reflect the real value of health care resources rather than simply applying their unit costs. The analyses informing the WHO Guidelines are re-estimated by implementing scenarios using this framework, informing how differentiated care can be prioritized to generate greatest gains in population health. IMPLICATIONS: The findings have important implications for how economic analyses should be undertaken and reported in HIV and other disease areas. Results provide guidance on conditions under which viral load informed differentiated care will more likely prove to be cost effective when implemented
Real-Time Detection and Rapid Multiwavelength Follow-up Observations of a Highly Subluminous Type II-P Supernova from the Palomar Transient Factory Survey
The Palomar Transient Factory (PTF) is an optical wide-field variability
survey carried out using a camera with a 7.8 square degree field of view
mounted on the 48-in Oschin Schmidt telescope at Palomar Observatory. One of
the key goals of this survey is to conduct high-cadence monitoring of the sky
in order to detect optical transient sources shortly after they occur. Here, we
describe the real-time capabilities of the PTF and our related rapid
multiwavelength follow-up programs, extending from the radio to the gamma-ray
bands. We present as a case study observations of the optical transient
PTF10vdl (SN 2010id), revealed to be a very young core-collapse (Type II-P)
supernova having a remarkably low luminosity. Our results demonstrate that the
PTF now provides for optical transients the real-time discovery and
rapid-response follow-up capabilities previously reserved only for high-energy
transients like gamma-ray bursts.Comment: ApJ, in press; all spectroscopic data available from the Weizmann
Institute of Science Experimental Astrophysics Spectroscopy System (WISEASS;
http://www.weizmann.ac.il/astrophysics/wiseass/
High star formation rates as the origin of turbulence in early and modern disk galaxies
High spatial and spectral resolution observations of star formation and
kinematics in early galaxies have shown that two-thirds are massive rotating
disk galaxies with the remainder being less massive non-rotating objects. The
line of sight averaged velocity dispersions are typically five times higher
than in today's disk galaxies. This has suggested that
gravitationally-unstable, gas-rich disks in the early Universe are fuelled by
cold, dense accreting gas flowing along cosmic filaments and penetrating hot
galactic gas halos. However these accreting flows have not been observed, and
cosmic accretion cannot power the observed level of turbulence. Here we report
on a new sample of rare high-velocity-dispersion disk galaxies we have
discovered in the nearby Universe where cold accretion is unlikely to drive
their high star-formation rates. We find that the velocity dispersion is most
fundamentally correlated with their star-formation rates, and not their mass
nor gas fraction, which leads to a new picture where star formation itself is
the energetic driver of galaxy disk turbulence at all cosmic epochs.Comment: 9 pages, 2 figures, Supplimentary Info available at:
http://pulsar.swin.edu.au/~agreen/nature/sigma_mean_arXiv.pdf. Accepted for
publication in Natur
A topological insulator surface under strong Coulomb, magnetic and disorder perturbations
Three dimensional topological insulators embody a newly discovered state of
matter characterized by conducting spin-momentum locked surface states that
span the bulk band gap as demonstrated via spin-resolved ARPES measurements .
This highly unusual surface environment provides a rich ground for the
discovery of novel physical phenomena. Here we present the first controlled
study of the topological insulator surfaces under strong Coulomb, magnetic and
disorder perturbations. We have used interaction of iron, with a large Coulomb
state and significant magnetic moment as a probe to \textit{systematically test
the robustness} of the topological surface states of the model topological
insulator BiSe. We observe that strong perturbation leads to the
creation of odd multiples of Dirac fermions and that magnetic interactions
break time reversal symmetry in the presence of band hybridization. We also
present a theoretical model to account for the altered surface of BiSe.
Taken collectively, these results are a critical guide in manipulating
topological surfaces for probing fundamental physics or developing device
applications.Comment: 14 pages, 4 Figures. arXiv admin note: substantial text overlap with
arXiv:1009.621
Constraints on the Progenitor System of the Type Ia Supernova SN 2011fe/PTF11kly
Type Ia supernovae (SNe) serve as a fundamental pillar of modern cosmology,
owing to their large luminosity and a well-defined relationship between
light-curve shape and peak brightness. The precision distance measurements
enabled by SNe Ia first revealed the accelerating expansion of the universe,
now widely believed (though hardly understood) to require the presence of a
mysterious "dark" energy. General consensus holds that Type Ia SNe result from
thermonuclear explosions of a white dwarf (WD) in a binary system; however,
little is known of the precise nature of the companion star and the physical
properties of the progenitor system. Here we make use of extensive historical
imaging obtained at the location of SN 2011fe/PTF11kly, the closest SN Ia
discovered in the digital imaging era, to constrain the visible-light
luminosity of the progenitor to be 10-100 times fainter than previous limits on
other SN Ia progenitors. This directly rules out luminous red giants and the
vast majority of helium stars as the mass-donating companion to the exploding
white dwarf. Any evolved red companion must have been born with mass less than
3.5 times the mass of the Sun. These observations favour a scenario where the
exploding WD of SN 2011fe/PTF11kly, accreted matter either from another WD, or
by Roche-lobe overflow from a subgiant or main-sequence companion star.Comment: 22 pages, 6 figures, submitte
KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra
We announce the discovery of a highly inflated transiting hot Jupiter
discovered by the KELT-North survey. A global analysis including constraints
from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly
evolved, G dwarf with K, , , an inferred mass
M, and radius
R. The planetary companion has mass , radius
, surface gravity , and density
g cm. The planet is on a roughly
circular orbit with semimajor axis AU and
eccentricity . The best-fit linear ephemeris is
BJD and
days. This planet is one of the most inflated of all known transiting
exoplanets, making it one of the few members of a class of extremely low
density, highly-irradiated gas giants. The low stellar and large
implied radius are supported by stellar density constraints from follow-up
light curves, plus an evolutionary and space motion analysis. We also develop a
new technique to extract high precision radial velocities from noisy spectra
that reduces the observing time needed to confirm transiting planet candidates.
This planet boasts deep transits of a bright star, a large inferred atmospheric
scale height, and a high equilibrium temperature of
K, assuming zero albedo and perfect heat redistribution, making it one of the
best targets for future atmospheric characterization studies.Comment: Submitted to ApJ, feedback is welcom
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