312 research outputs found
Evidence of a link between the evolution of clusters and their AGN fraction
‘The definitive version is available at www3.interscience.wiley.com .' Copyright Blackwell Publishing / Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.14513.xPeer reviewe
Multi-object spectroscopy of low-redshift EIS clusters IV. Reliability of matched-filter results at z~0.3-0.4
abridged) In this paper we present new redshifts for 747 galaxies in 23 ESO
Imaging Survey (EIS) cluster fields. We use the "gap"-technique to search for
significant overdensities in redshift space for identifying groups/clusters of
galaxies. In this way we spectroscopically confirm systems in 10 of the 23
cluster candidate fields with a matched-filter estimated redshift z_MF=0.3-0.4
and with spectroscopic redshifts in the range from z=0.158 to z=0.534. We find
that the systems identified in the present paper span a broad range of
one-dimensional velocity dispersion (175-497 km/s) and richness
(12L*<=L<=65L*). Both undersampling and contamination by substructures
contribute to the uncertainty of these measurements. From the analysis of the
colours of the galaxy populations we find that ~60% of the spectroscopically
confirmed systems have a "significant" red sequence with a colour matching
passive stellar evolution models. With this paper we complete our spectroscopic
survey of the fields of 58 EIS cluster candidates with estimated redshifts
z<=0.4. We have measured a total of 1954 galaxy redshifts in the range z=0.0065
to z=0.6706. Of the 58 systems we confirm 42 (~75%) with redshifts between
z=0.095 and z=0.534.Comment: Accepted for publication in A&A, 19 pages, 11 figure
Vitalum study design: RCT evaluating the efficacy of tailored print communication and telephone motivational interviewing on multiple health behaviors
Abstract
Background
A large proportion of adults fail to meet public health guidelines for physical activity as well as fruit, vegetable and fat intake. Interventions are needed to improve these health behaviors. Both computer tailoring and motivational interviewing have shown themselves to be promising techniques for health behavior change. The Vitalum project aims to compare the efficacy of these techniques in improving the health behaviors of adults aged 45–70. This paper describes the design of the Vitalum study.
Methods/Design
Dutch general medical practices (N = 23) were recruited via a registration network or by personal invitation. The participants were then enrolled through these general practices using an invitational letter. They (n = 2,881) received a written baseline questionnaire to assess health behaviors, and potential psychosocial and socio-demographic behavioral determinants. A power analysis indicated that 1,600 participants who were failing to meet the guidelines for physical activity and either fruit or vegetable consumption were needed. Eligible participants were stratified based on hypertension status and randomized into one of four intervention groups: tailored print communication, telephone motivational interviewing, combined, and control. The first two groups either received four letters or took part in four interviews, whereas the combined group received two letters and took part in two interviews in turns at 5, 13, 30 and 43 weeks after returning the baseline questionnaire. Each letter and interview focused on physical activity or nutrition behavior. The participants also took part in a telephone survey 25 weeks after baseline to gather new information for tailoring. There were two follow-up questionnaires, at 47 and 73 weeks after baseline, to measure short- and long-term effects. The control group received a tailored letter after the last posttest. The process, efficacy and cost-effectiveness of the interventions will be examined by means of multilevel mixed regression, cost-effectiveness analyses and process evaluation.
Discussion
The Vitalum study simultaneously evaluates the efficacy of tailored print communication and telephone motivational interviewing, and their combined use for multiple behaviors and people with different motivational stages and education levels. The results can be used by policymakers to contribute to evidence-based prevention of chronic diseases.
Trial Registration
Dutch Trial Register NTR1068http://deepblue.lib.umich.edu/bitstream/2027.42/112919/1/12889_2008_Article_1186.pd
3D-Matched-Filter Galaxy Cluster Finder I: Selection Functions and CFHTLS Deep Clusters
We present an optimised galaxy cluster finder, 3D-Matched-Filter (3D-MF),
which utilises galaxy cluster radial profiles, luminosity functions and
redshift information to detect galaxy clusters in optical surveys. This method
is an improvement over other matched-filter methods, most notably through
implementing redshift slicing of the data to significantly reduce line-of-sight
projections and related false positives. We apply our method to the
Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) Deep fields, finding ~170
galaxy clusters per square degree in the 0.2 <= z <= 1.0 redshift range. Future
surveys such as LSST and JDEM can exploit 3D-MF's automated methodology to
produce complete and reliable galaxy cluster catalogues. We determine the
reliability and accuracy of the statistical approach of our method through a
thorough analysis of mock data from the Millennium Simulation. We detect
clusters with 100% completeness for M_200 >= 3.0x10^(14)M_sun, 88% completeness
for M_200 >= 1.0x10^(14)M_sun, and 72% completeness well into the 10^(13)M_sun
cluster mass range. We show a 36% multiple detection rate for cluster masses >=
1.5x10^(13)M_sun and a 16% false detection rate for galaxy clusters >~
5x10^(13)M_sun, reporting that for clusters with masses <~ 5x10^(13)M_sun false
detections may increase up to ~24%. Utilising these selection functions we
conclude that our galaxy cluster catalogue is the most complete CFHTLS Deep
cluster catalogue to date.Comment: 18 pages, 17 figures, 5 tables; v2: added Fig 5, minor edits to match
version published in MNRA
Clustering of red galaxies around the z=1.53 quasar 3C270.1
In the paradigm of hierarchical galaxy formation, luminous radio galaxies
mark mass assembly peaks that should contain clusters of galaxies. Observations
of the z=1.53 quasar 3C270.1 with the Spitzer Space Telescope at 3.6-24 micron
and with the 6.5-m MMT in the z'- and Y-bands allow detection of potential
cluster members via photometric redshifts. Compared with nearby control fields,
there is an excess of 11 extremely red objects (EROs) at 1.33 < z_phot < 1.73,
consistent with a proto-cluster around the quasar. The spectral energy
distributions (SEDs) of 3/4 of the EROs are better fitted with passive
elliptical galaxies than withdust-reddened starbursts, and of four sources
well-detected on an archival HST snapshot image, all have undisturbed
morphologies. However, one ERO, not covered by the HST image, is a double
source with 0.8" separation on the z' image and a marginal (2sigma) 24 micron
detection indicating a dust-enshrouded starburst. The EROs are more luminous
than L* (H = -23.6 AB mag at z=1.5).Comment: 12 pages, 7 figures, accepted by Ap
The Subaru/XMM-Newton Deep Field - II. The 37 brightest radio sources
We study the 37 brightest radio sources in the Subaru/XMM-Newton Deep Field
(SXDF). We have spectroscopic redshifts for 24 of 37 objects and photometric
redshifts for the remainder, yielding a median redshift z_med for the whole
sample of z_med ~= 1.1 and a median radio luminosity close to the `FRI/FRII'
luminosity divide. Using mid-IR (Spitzer MIPS 24 um) data we expect to trace
nuclear accretion activity, even if it is obscured at optical wavelengths,
unless the obscuring column is extreme. Our results suggest that above the
FRI/FRII radio luminosity break most of the radio sources are associated with
objects that have excess mid-IR emission, only some of which are broad-line
objects, although there is one clear low-accretion-rate object with an FRI
radio structure. For extended steep-spectrum radio sources, the fraction of
objects with mid-IR excess drops dramatically below the FRI/FRII luminosity
break, although there exists at least one high-accretion-rate `radio-quiet'
QSO. We have therefore shown that the strong link between radio luminosity (or
radio structure) and accretion properties, well known at z ~ 0.1, persists to z
~ 1. Investigation of mid-IR and blue excesses shows that they are correlated
as predicted by a model in which, when significant accretion exists, a torus of
dust absorbs ~30% of the light, and the dust above and below the torus scatters
>~1% of the light.Comment: Accepted for publication by MNRAS; 39 pages, 7 figures, 4 table
Clusters of Galaxies in the First Half of the Universe from the IRAC Shallow Survey
We have identified 335 galaxy cluster and group candidates, 106 of which are
at z > 1, using a 4.5 um selected sample of objects from a 7.25 deg^2 region in
the Spitzer Infrared Array Camera (IRAC) Shallow Survey. Clusters were
identified as 3-dimensional overdensities using a wavelet algorithm, based on
photometric redshift probability distributions derived from IRAC and NOAO Deep
Wide-Field Survey data. We estimate only ~10% of the detections are spurious.
To date 12 of the z > 1 candidates have been confirmed spectroscopically, at
redshifts from 1.06 to 1.41. Velocity dispersions of ~750 km/s for two of these
argue for total cluster masses well above 10^14 M_sun, as does the mass
estimated from the rest frame near infrared stellar luminosity. Although not
selected to contain a red sequence, some evidence for red sequences is present
in the spectroscopically confirmed clusters, and brighter galaxies are
systematically redder than the mean galaxy color in clusters at all redshifts.
The mean I - [3.6] color for cluster galaxies up to z ~ 1 is well matched by a
passively evolving model in which stars are formed in a 0.1 Gyr burst starting
at redshift z_f = 3. At z > 1, a wider range of formation histories is needed,
but higher formation redshifts (i.e. z_f > 3) are favored for most clusters.Comment: 56 pages, 19 figures, 3 tables, landscape tables 1 (p. 14) and 2 (p.
29) should be printed separately. Accepted for publication in Astrophysical
Journal, updated version will be posted upon publicatio
Current challenges in software solutions for mass spectrometry-based quantitative proteomics
This work was in part supported by the PRIME-XS project, grant agreement number 262067, funded by the European Union seventh Framework Programme; The Netherlands Proteomics Centre, embedded in The Netherlands Genomics Initiative; The Netherlands Bioinformatics Centre; and the Centre for Biomedical Genetics (to S.C., B.B. and A.J.R.H); by NIH grants NCRR RR001614 and RR019934 (to the UCSF Mass Spectrometry Facility, director: A.L. Burlingame, P.B.); and by grants from the MRC, CR-UK, BBSRC and Barts and the London Charity (to P.C.
Adherence to Mediterranean and low-fat diets among heart and lung transplant recipients: a randomized feasibility study
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