3,409 research outputs found
Development of a critical appraisal tool to assess the quality of cross-sectional studies (AXIS)
Objectives: The aim of this study was to develop a critical appraisal (CA) tool that addressed study design and reporting quality as well as the risk of bias in cross-sectional studies (CSSs). In addition, the aim was to produce a help document to guide the non-expert user through the tool.
Design: An initial scoping review of the published literature and key epidemiological texts was undertaken prior to the formation of a Delphi panel to establish key components for a CA tool for CSSs. A consensus of 80% was required from the Delphi panel for any component to be included in the final tool.
Results: An initial list of 39 components was identified through examination of existing resources. An international Delphi panel of 18 medical and veterinary experts was established. After 3 rounds of the Delphi process, the Appraisal tool for Cross-Sectional Studies (AXIS tool) was developed by consensus and consisted of 20 components. A detailed explanatory document was also developed with the tool, giving expanded explanation of each question and providing simple interpretations and examples of the epidemiological concepts being examined in each question to aid non-expert users.
Conclusions: CA of the literature is a vital step in evidence synthesis and therefore evidence-based decision-making in a number of different disciplines. The AXIS tool is therefore unique and was developed in a way that it can be used across disciplines to aid the inclusion of CSSs in systematic reviews, guidelines and clinical decision-making
The Complex Structure of the Multi-Phase Galactic Wind in a Starburst Merger
Neutral outflows have been detected in many ultraluminous infrared galaxies
(ULIRGs) via the Na I D absorption-line doublet.
For the first time, we have mapped and analyzed the 2-D kinematics of a cool
neutral outflow in a ULIRG, F10565+2448, using the integral field unit (IFU) on
Gemini North to observe the Na I D feature. At the same time we have mapped the
ionized outflow with the [NII] and H emission lines. We find a systemic
rotation curve that is consistent with the rotation of the molecular disk
determined from previous CO observations. The absorption lines show evidence of
a nuclear outflow with a radial extent of at least 3 kpc, consistent with
previous observations. The strength of the Na I D lines have a strong,
spatially resolved correlation with reddening, suggesting that dust is present
in the outflow. Surprisingly, the outflow velocities of the neutral gas show a
strong asymmetry in the form of a major-axis gradient that is opposite in sign
to disk rotation. This is inconsistent with entrained material rotating along
with the galaxy or with a tilted minor-axis outflow. We hypothesize that this
unusual behavior is due to an asymmetry in the distribution of the ambient gas.
We also see evidence of asymmetric ionized outflow in the emission-line
velocity map, which appear to be decoupled from the neutral outflow. Our
results strengthen the hypothesis that ULIRG outflows differ in morphology from
those in more quiescent disk galaxies.Comment: Accepted to Ap
Use of clinical vignette questionnaires to investigate the variation in management of keratoconjunctivitis sicca and acute glaucoma in dogs
There is little peer-reviewed research assessing therapeutic effectiveness in canine eye disease. Current treatments used in first opinion and ophthalmology referral practices are also somewhat poorly documented. The aim of this study was to investigate the current management of canine keratoconjunctivitis sicca (KCS) and acute primary angle-closure glaucoma (PACG) by veterinary surgeons. Questionnaires using clinical vignettes were administered to a cross section of general practitioners (‘GPs’) and veterinarians engaged in or training for postgraduate ophthalmology practice (’PGs’). Similar treatment recommendations for KCS (topical cyclosporine, lubricant, antibiotic) were given by both groups of veterinarians with the single exception of increased topical antibiotic use by GPs. Treatment of acute glaucoma diverged between groups: PGs were much more likely to recommend topical prostaglandin analogues (PGAs) and a wider array of both topical and systemic treatments were recommended by both groups. Systemic ocular hypotensive agents were suggested infrequently. Our results suggest that treatments may vary substantially in ocular conditions, particularly in conditions for which neither guidelines nor high quality evidence exists. This study highlights the need for novel strategies to address evidence gaps in veterinary medicine, as well as for better evaluation and dissemination of current treatment experience
Demographics and economic burden of un-owned cats and dogs in the UK: results of a 2010 census
Background
The population of dogs and cats passing through rescue shelters may be subject to compromised welfare and increased susceptibility to disease. Little information exists to describe this population, its dynamics and associated management practices. The aim of this study was to carry out a census of un-owned cats and dogs in the UK in 2010, and to document the origins, destinations, husbandry and costs associated with the care of these animals.
Results
A sampling frame was constructed by searching the databases of publicly registered charities for England, Scotland and Wales, registers of breed rescues, and by internet searches of animal welfare websites. Overall, 2,352 contacts for 1,380 organisations were identified. All were sent a postal questionnaire asking for data on the number of dogs and cats housed, their origins and eventual outcomes, and details of husbandry between January 1st and December 31st 2010. For those which were registered charities (595), financial records were also obtained.
A response rate of 38.8% was obtained. Overall, in 2010, 89,571 dogs and 156,826 cats entered the care of the participating organisations. Approximately half of these animals were relinquished by their owners. Other origins included being found as strays or confiscated for welfare purposes. Seventy-five per cent of dogs and 77.1% of cats were rehomed. The next most common outcome was euthanasia, accounting for 10.4% of dogs and 13.2% cats. For dogs and cats, 44.3% and 62% of participants respectively reported having a waiting list, which frequently exceeded the actual capacity of the facility. Over 19,000 people were involved in the care of these animals, on a paid or voluntary basis. Financial records were available for 519/595 (87.2%) of the registered charities, and their total expenditure in 2010 was £340 million.
Conclusions
This study showed that a large number of animals become un-owned each year, which could have considerable implications for their welfare. Despite the resources expended, demand still exceeds capacity for many organisations, and a substantial number of both cats and dogs are euthanased, suggesting that further understanding of how and why these animals become un-owned is essential in order to target interventions
Radiation Pressure Driven Galactic Winds from Self-Gravitating Discs
(Abridged) We study large-scale winds driven from uniformly bright
self-gravitating discs radiating near the Eddington limit. We show that the
ratio of the radiation pressure force to the gravitational force increases with
height above the disc surface to a maximum of twice the value of the ratio at
the disc surface. Thus, uniformly bright self-gravitating discs radiating at
the Eddington limit are fundamentally unstable to driving large-scale winds.
These results contrast with the spherically symmetric case, where
super-Eddington luminosities are required for wind formation. We apply this
theory to galactic winds from rapidly star-forming galaxies that approach the
Eddington limit for dust. For hydrodynamically coupled gas and dust, we find
that the asymptotic velocity of the wind is v_\infty ~ 1.5 v_rot and that
v_\infty SFR^{0.36}, where v_rot is the disc rotation velocity and SFR is the
star formation rate, both of which are in agreement with observations. However,
these results of the model neglect the gravitational potential of the
surrounding dark matter halo and an old passive stellar bulge or extended disc,
which act to decrease v_\infty. A more realistic treatment shows that the flow
can either be unbound, or bound, forming a "fountain flow" with a typical
turning timescale of t_turn ~ 0.1-1 Gyr. We provide quantitative criteria and
scaling relations for assessing whether or not a rapidly star-forming galaxy of
given properties can drive unbound flows via the mechanism described in this
paper. Importantly, we note that because t_turn is longer than the star
formation timescale in the rapidly star-forming galaxies and ULIRGs for which
our theory is most applicable, if rapidly star-forming galaxies are selected as
such, they may be observed to have strong outflows, even though their winds are
eventually bound on large scales.Comment: 10 pages, 6 figures, Accepted for publication in MNRA
Evidence for ablated flows in the shell of nova DQ Her
High-resolution longslit Halpha spectra of the shell of the old nova DQ Her
have been obtained with the William Herschel Telescope using the ISIS
spectrograph. An equatorial expansion velocity of 370+/-14 km/s is derived from
the spectra which, in conjunction with a narrowband Halpha image of the
remnant, allows a distance estimate of 525+/-28 pc. An equatorial ring which
exhibits enhanced [NII] emission has also been detected and the inclination
angle of the shell is found to be 86.8+/-0.2 degrees with respect to the line
of sight. The spectra also reveal tails extending from the clumps in the shell,
which have a radial velocity increasing along their length. This suggests the
presence of a stellar wind, collimated in the polar direction, which ablates
fragments of material from the clumps and accelerates them into its stream up
to a terminal velocity of order 800-900 km/s.Comment: 7 pages, 6 figure
Irish Universities in the Knowledge Society: Society's Sentinels and the Citizen's vade mecum.
This is not an attempt to explore what the proper core role of universities should be
through the insights o f educators and of the great liberal traditions to which many
subscribe, precious and excellent though they may be. Instead, this is an attempt to
explore the essential requirements o f society from universities, requirements that are
necessarily implicit in the currently conventional vision of our future as a technically
and economically advanced economy in an even more rapidly changing world, the
Knowledge Society. If these two approaches tend to converge in their findings then
we must think that the role of universities is made so much the clearer
Kepler Observations of V447 Lyr: An Eclipsing U Gem Cataclysmic Variable
We present the results of an analysis of data covering 1.5 years of the dwarf
nova V447 Lyr. We detect eclipses of the accretion disk by the mass donating
secondary star every 3.74 hrs which is the binary orbital period. V447 Lyr is
therefore the first dwarf nova in the Kepler field to show eclipses. We also
detect five long outbursts and six short outbursts showing V447 Lyr is a U Gem
type dwarf nova. We show that the orbital phase of the mid-eclipse occurs
earlier during outbursts compared to quiescence and that the width of the
eclipse is greater during outburst. This suggests that the bright spot is more
prominent during quiescence and that the disk is larger during outburst than
quiescence. This is consistent with an expansion of the outer disk radius due
to the presence of high viscosity material associated with the outburst,
followed by a contraction in quiescence due to the accretion of low angular
momentum material. We note that the long outbursts appear to be triggered by a
short outburst, which is also observed in the super-outbursts of SU UMa dwarf
novae as observed using Kepler.Comment: Accepted by MNRA
Effects Of Circum-nuclear Disk Gas Evolution And The Spin Of Central Black Holes
Mass and spin are the only two parameters needed to completely characterize
black holes in General Relativity. However, the interaction between black holes
and their environment is where complexity lies, as the relevant physical
processes occur over a large range of scales. That is particularly relevant in
the case of super-massive black holes (SMBHs), hosted in galaxy centers, and
surrounded by swirling gas and various generations of stars. These compete with
the SMBH for gas consumption and affect both dynamics and thermodynamics of the
gas itself. How the behavior of such fiery environment influence the angular
momentum of the gas accreted onto SMBHs, and, hence, black-hole spins is
uncertain. We explore the interaction between SMBHs and their environment via
first 3D sub-parsec resolution simulations (ranging from 0.1 pc to 1 kpc
scales) that study the evolution of the SMBH spin by including the effects of
star formation, stellar feedback, radiative transfer, and metal pollution
according to the proper stellar yields and lifetimes. This approach is crucial
to investigate the impact of star formation processes and feedback effects on
the angular momentum of the material that could accrete on the central hole. We
find that star formation and feedback mechanisms can locally inject significant
amounts of entropy in the surrounding medium, and impact on the inflow
inclination angles and Eddington fractions. As a consequence, the resulting
trends show upper-intermediate equilibrium values for the spin parameter, a, of
about 0.6 - 0.9, corresponding to radiative efficiencies \epsilon = 9% - 15%.
These results suggest that star formation feedback taking place in the
circum-nuclear disk during the in-fall cannot induce alone very strong chaotic
trends in the gas flow, quite independently from the different numerical
parameters.Comment: Changes in title and updates in references. Inclusion of additional
runs and parameter studies. Conclusions unaffected. Accepte
An HI shell-like structure associated with nova V458 Vulpeculae?
We report the radio detection of a shell-like HI structure in proximity to,
and probably associated with, the nova V458 Vul. High spectral resolution
observation with the Giant Metrewave Radio Telescope has made it possible to
study the detailed kinematics of this broken and expanding shell. Unlike the
diffuse Galactic HI emission, this is a single velocity component emission with
significant clumping at ~ 0.5' scales. The observed narrow line width of ~ 5
km/s suggests that the shell consists of mostly cold gas. Assuming a distance
of 13 kpc to the system, as quoted in the literature, the estimated HI mass of
the nebula is about 25 M_sun. However, there are some indications that the
system is closer than 13 kpc. If there is a physical association of the HI
structure and the nova system, the asymmetric morphology and the off-centred
stellar system indicates past strong interaction of the mass loss in the
asymptotic giant branch phase with the surrounding interstellar medium. So far,
this is the second example, after GK Per, of a large HI structure associated
with a classical nova.Comment: 6 pages, 2 table, 3 figures. Accepted for publication in MNRAS
Letters. The definitive version will be available at
http://www.blackwell-synergy.com
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