17 research outputs found
Groups of Galaxies in the Two Micron All-Sky Redshift Survey
We present the results of applying a percolation algorithm to the initial
release of the Two Micron All-Sky Survey Extended Source Catalog, using
subsequently measured redshifts for almost all of the galaxies with K < 11.25
mag. This group catalog is based on the first near-IR all-sky flux-limited
survey that is complete to |b| = 5 deg. We explore the dependence of the
clustering on the length and velocity scales involved. The paper describes a
group catalog, complete to a limiting redshift of 10,000 km/s, created by
maximizing the number of groups containing 3 or more members. A second catalog
is also presented, created by requiring a minimum density contrast of 80 to
identify groups. We identify known nearby clusters in the catalogs and contrast
the groups identified in the two catalogs. We examine and compare the
properties of the determined groups and verify that the results are consistent
with the UZC-SSRS2 and northern CfA redshift survey group catalogs. The all-sky
nature of the catalog will allow the development of a flow-field model based on
the density field inferred from the estimated cluster masses.Comment: Accepted for publication in ApJ (29 pages including 13 figures). A
version with high-resolution figures is available at
http://www.cfa.harvard.edu/~acrook/preprints
Reconstructing the Peculiar Velocity of the Local Group with Modified Gravity and 2MASS
The peculiar velocity of the Local Group, reconstructed from inhomogeneities
in the local density field, differs in direction and magnitude from the
velocity inferred from the Cosmic Microwave Background dipole. We investigate
whether generalized theories of gravity, which predict a modified growth of
perturbations, are able to alleviate this discrepancy. We introduce a general
formalism for calculating the real-space peculiar-velocity field for modified
gravity and theories with interactions in the dark sector. For different
classes of theories - scalar tensor and higher-dimensional gravity - we
reconstruct the Local Group peculiar velocity using groups of galaxies
identified in the 2MASS Redshift Survey. We show that, for realistic
parameters, modifications to General Relativity cannot account for the angular
discrepancy between the reconstructed Local Group velocity and the dipole in
the Cosmic Microwave Background.Comment: 14 pages, 7 figure
2MTF â II. New Parkes 21-cm observations of 303 southern galaxies
We present new 21-cm neutral hydrogen (HI) observations of spiral galaxies
for the 2MASS Tully Fisher (2MTF) survey. Using the 64-m Parkes radio telescope
multibeam system we obtain 152 high signal-to-noise HI spectra from which we
extract 148 high-accuracy (< 5% error) velocity widths and derive reliable
rotation velocities. The observed sample consists of 303 southern (\delta <
-40\deg) galaxies selected from the MASS Redshift Survey (2MRS) with K_s <11.25
mag, cz < 10,000 km/s and axis ratio b/a < 0.5. The HI observations reported in
this paper will be combined with new HI spectra from the Green Bank and Arecibo
telescopes, together producing the most uniform Tully-Fisher survey ever
constructed (in terms of sky coverage). In particular, due to its near infrared
selection, 2MTF will be significantly more complete at low Galactic latitude
(|b|<15\deg) and will provide a more reliable map of peculiar velocities in the
local universe.Comment: 11 pages, 12 figures, 3 tables, accepted for publication in MNRA
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
Developing a core outcome set for fistulising perianal Crohn's disease
OBJECTIVE: Lack of standardised outcomes hampers effective analysis and comparison of data when comparing treatments in fistulising perianal Crohn's disease (pCD). Development of a standardised set of outcomes would resolve these issues. This study provides the definitive core outcome set (COS) for fistulising pCD. DESIGN: Candidate outcomes were generated through a systematic review and patient interviews. Consensus was established via a three-round Delphi process using a 9-point Likert scale based on how important they felt it was in determining treatment success culminating in a final consensus meeting. Stakeholders were recruited nationally and grouped into three panels (surgeons and radiologists, gastroenterologists and IBD specialist nurses, and patients). Participants received feedback fromtheir panel(in the second round) andall participants(in the third round) to allow refinement of their scores. RESULTS: A total of 295 outcomes were identified from systematic reviews and interviews that were categorised into 92 domains. 187 stakeholders (response rate 78.5%) prioritised 49 outcomes through a three-round Delphi study.The final consensus meeting of 41 experts and patients generated agreement on an eight domain COS. The COS comprised three patient-reported outcome domains (quality of life, incontinence and a combined score of patient priorities) and five clinician-reported outcome domains (perianal disease activity, development of new perianal abscess/sepsis, new/recurrent fistula, unplanned surgery and faecal diversion). CONCLUSION: A fistulising pCD COS has been produced by all key stakeholders. Application of the COS will reduce heterogeneity in outcome reporting, thereby facilitating more meaningful comparisons between treatments, data synthesis and ultimately benefit patient care
The 2MASS Redshift Survey - Description and Data Release
We present the results of the 2MASS Redshift Survey (2MRS), a ten-year
project to map the full three-dimensional distribution of galaxies in the
nearby Universe. The 2 Micron All-Sky Survey (2MASS) was completed in 2003 and
its final data products, including an extended source catalog (XSC), are
available on-line. The 2MASS XSC contains nearly a million galaxies with Ks <=
13.5 mag and is essentially complete and mostly unaffected by interstellar
extinction and stellar confusion down to a galactic latitude of |b|=5 deg for
bright galaxies. Near-infrared wavelengths are sensitive to the old stellar
populations that dominate galaxy masses, making 2MASS an excellent starting
point to study the distribution of matter in the nearby Universe.
We selected a sample of 44,599 2MASS galaxies with Ks =5
deg (>= 8 deg towards the Galactic bulge) as the input catalog for our survey.
We obtained spectroscopic observations for 11,000 galaxies and used
previously-obtained velocities for the remainder of the sample to generate a
redshift catalog that is 97.6% complete to well-defined limits and covers 91%
of the sky. This provides an unprecedented census of galaxy (baryonic mass)
concentrations within 300 Mpc.
Earlier versions of our survey have been used in a number of publications
that have studied the bulk motion of the Local Group, mapped the density and
peculiar velocity fields out to 50 Mpc, detected galaxy groups, and estimated
the values of several cosmological parameters.
Additionally, we present morphological types for a nearly-complete sub-sample
of 20,860 galaxies with Ks = 10 deg.Comment: Accepted for publication in The Astrophysical Journal Supplement
Series. The 2MRS catalogs and a version of the paper with higher-resolution
figures can be found at http://tdc-www.harvard.edu/2mrs
Developing a core outcome set for fistulising perianal Crohn's disease
ObjectiveâLack of standardised outcomes hampers effective analysis and comparison of data when comparing treatments in fistulising perianal Crohnâs disease (pCD). Development of a standardised set of outcomes would resolve these issues. This study provides the definitive core outcome set (COS) for fistulising pCD. DesignâCandidate outcomes were generated through a systematic review and patient interviews. Consensus was established via a three-round Delphi process using a 9-point Likert scale based on how important they felt it was in determining treatment success culminating in a final consensus meeting. Stakeholders were recruited nationally and grouped into three panels (surgeons and radiologists, gastroenterologists and IBD specialist nurses, and patients). Participants received feedback from their panel (in the second round) and all participants (in the third round) to allow refinement of their scores. ResultsâA total of 295 outcomes were identified from systematic reviews and interviews that were categorised into 92 domains. 187 stakeholders (response rate 78.5%) prioritised 49 outcomes through a three-round Delphi study. The final consensus meeting of 41 experts and patients generated agreement on an eight domain COS. The COS comprised three patient-reported outcome domains (quality of life, incontinence and a combined score of patient priorities) and five clinician-reported outcome domains (perianal disease activity, development of new perianal abscess/sepsis, new/recurrent fistula, unplanned surgery and faecal diversion). ConclusionâA fistulising pCD COS has been produced by all key stakeholders. Application of the COS will reduce heterogeneity in outcome reporting, thereby facilitating more meaningful comparisons between treatments, data synthesis and ultimately benefit patient care