218 research outputs found
The distribution of satellites around massive galaxies at 1<z<3 in ZFOURGE/CANDELS: dependence on star formation activity
We study the statistical distribution of satellites around star-forming and
quiescent central galaxies at 1<z<3 using imaging from the FourStar Galaxy
Evolution Survey (ZFOURGE) and the Cosmic Assembly Near-IR Deep Extragalactic
Legacy Survey (CANDELS). The deep near-IR data select satellites down to
at z<3. The radial satellite distribution around centrals
is consistent with a projected NFW profile. Massive quiescent centrals,
, have 2 times the number of satellites compared
to star-forming centrals with a significance of 2.7 even after
accounting for differences in the centrals' stellar-mass distributions. We find
no statistical difference in the satellite distributions of intermediate-mass
quiescent and star-forming centrals, . Comparing
to the Guo2011 semi-analytic model, the excess number of satellites indicates
that quiescent centrals have halo masses 0.3 dex larger than star-forming
centrals, even when the stellar-mass distributions are fixed. We use a simple
toy model that relates halo mass and quenching, which roughly reproduces the
observed quenched fractions and the differences in halo mass between
star-forming and quenched galaxies only if galaxies have a quenching
probability that increases with halo mass from 0 for
11 to 1 for 13.5. A single
halo-mass quenching threshold is unable to reproduce the quiescent fraction and
satellite distribution of centrals. Therefore, while halo quenching may be an
important mechanism, it is unlikely to be the only factor driving quenching. It
remains unclear why a high fraction of centrals remain star-forming even in
relatively massive halos.Comment: 19 pages, 17 figures, accepted by ApJ. Information on ZFOURGE can be
found at http://zfourge.tamu.ed
The XMM cluster survey: Testing chameleon gravity using the profiles of clusters
The chameleon gravity model postulates the existence of a scalar field that couples with matter to mediate a fifth force. If it exists, this fifth force would influence the hot X-ray emitting gas filling the potential wells of galaxy clusters. However, it would not influence the clusters weak lensing signal. Therefore, by comparing X-ray and weak lensing profiles, one can place upper limits on the strength of a fifth force. This technique has been attempted before using a single, nearby cluster (Coma, z = 0.02). Here we apply the technique to the stacked profiles of 58 clusters at higher redshifts (0.1 R0| R0| on cosmological scales. We hope to improve this constraint in future by extending the study to hundreds of clusters using data from the Dark Energy Survey
ZFOURGE/CANDELS: On the Evolution of \u3cem\u3eM\u3c/em\u3e* Galaxy Progenitors from \u3cem\u3ez\u3c/em\u3e=3 to 0.5*
Galaxies with stellar masses near M* contain the majority of stellar mass in the universe, and are therefore of special interest in the study of galaxy evolution. The Milky Way (MW) and Andromeda (M31) have present-day stellar masses near M*, at 5 Ă 1010 M â (defined here to be MW-mass) and 1011 M â (defined to be M31-mass). We study the typical progenitors of these galaxies using the FOURSTAR Galaxy Evolution Survey (ZFOURGE). ZFOURGE is a deep medium-band near-IR imaging survey, which is sensitive to the progenitors of these galaxies out to z ~ 3. We use abundance-matching techniques to identify the main progenitors of these galaxies at higher redshifts. We measure the evolution in the stellar mass, rest-frame colors, morphologies, far-IR luminosities, and star formation rates, combining our deep multiwavelength imaging with near-IR Hubble Space Telescope imaging from Cosmic Near-IR Deep Extragalactic Legacy Survey (CANDELS), and Spitzer and Herschel far-IR imaging from Great Observatories Origins Deep Survey-Herschel and CANDELS-Herschel. The typical MW-mass and M31-mass progenitors passed through the same evolution stages, evolving from blue, star-forming disk galaxies at the earliest stages to redder dust-obscured IR-luminous galaxies in intermediate stages and to red, more quiescent galaxies at their latest stages. The progenitors of the MW-mass galaxies reached each evolutionary stage at later times (lower redshifts) and with stellar masses that are a factor of two to three lower than the progenitors of the M31-mass galaxies. The process driving this evolution, including the suppression of star formation in present-day M* galaxies, requires an evolving stellar-mass/halo-mass ratio and/or evolving halo-mass threshold for quiescent galaxies. The effective size and SFRs imply that the baryonic cold-gas fractions drop as galaxies evolve from high redshift to z ~ 0 and are strongly anticorrelated with an increase in the SĂ©rsic index. Therefore, the growth of galaxy bulges in M* galaxies corresponds to a rapid decline in the galaxy gas fractions and/or a decrease in the star formation efficiency
Stone formation in peach fruit exhibits spatial coordination of the lignin and flavonoid pathways and similarity to Arabidopsis dehiscence
<p>Abstract</p> <p>Background</p> <p>Lignification of the fruit endocarp layer occurs in many angiosperms and plays a critical role in seed protection and dispersal. This process has been extensively studied with relationship to pod shatter or dehiscence in <it>Arabidopsis</it>. Dehiscence is controlled by a set of transcription factors that define the fruit tissue layers and whether or not they lignify. In contrast, relatively little is known about similar processes in other plants such as stone fruits which contain an extremely hard lignified endocarp or stone surrounding a single seed.</p> <p>Results</p> <p>Here we show that lignin deposition in peach initiates near the blossom end within the endocarp layer and proceeds in a distinct spatial-temporal pattern. Microarray studies using a developmental series from young fruits identified a sharp and transient induction of phenylpropanoid, lignin and flavonoid pathway genes concurrent with lignification and subsequent stone hardening. Quantitative polymerase chain reaction studies revealed that specific phenylpropanoid (phenylalanine ammonia-lyase and cinnamate 4-hydroxylase) and lignin (caffeoyl-CoA O-methyltransferase, peroxidase and laccase) pathway genes were induced in the endocarp layer over a 10 day time period, while two lignin genes (<it>p-</it>coumarate 3-hydroxylase and cinnamoyl CoA reductase) were co-regulated with flavonoid pathway genes (chalcone synthase, dihydroflavanol 4-reductase, leucoanthocyanidin dioxygen-ase and flavanone-3-hydrosylase) which were mesocarp and exocarp specific. Analysis of other fruit development expression studies revealed that flavonoid pathway induction is conserved in the related Rosaceae species apple while lignin pathway induction is not. The transcription factor expression of peach genes homologous to known endocarp determinant genes in <it>Arabidopsis </it>including <it>SHATTERPROOF</it>, <it>SEEDSTCK </it>and <it>NAC SECONDARY WALL THICENING PROMOTING FACTOR 1 </it>were found to be specifically expressed in the endocarp while the negative regulator <it>FRUITFU</it>L predominated in exocarp and mesocarp.</p> <p>Conclusions</p> <p>Collectively, the data suggests, first, that the process of endocarp determination and differentiation in peach and <it>Arabidopsis </it>share common regulators and, secondly, reveals a previously unknown coordination of competing lignin and flavonoid biosynthetic pathways during early fruit development.</p
ICF components of corresponding outcome measures in flexor tendon rehabilitation â a systematic review
<p>Abstract</p> <p>Background</p> <p>The International Classification of Functioning, Disability and Health (ICF) delivers a holistic approach to health conditions. The objective of the present study is to provide an overview of flexor tendon rehabilitation outcome measures with respect to ICF components. Furthermore, it aims to investigate to which extent current assessments measure aspects of health according to these components primarily focussing on <it>activity </it>and <it>participation</it>.</p> <p>Methods</p> <p>A systematic literature review was conducted to identify all studies meeting the inclusion criteria. Studies were only included if they assessed more than <it>body function and body structure </it>and referred to the ICF components <it>activity </it>and <it>participation</it>. The outcome measures were analysed and their linkage to the ICF components were investigated to examine to which degree aspects of health outcome as defined by the ICF were considered.</p> <p>Results</p> <p>As anticipated, the application of outcome measures after flexor tendon repair is non conform. In many studies the emphasis still lies on physical impairment neglecting activity limitations and participation restrictions.</p> <p>Aspects of health after flexor tendon repair could be assessed more adequately and cover patients' needs more sufficiently by choosing outcome measures which refer to all aspects of functioning.</p> <p>Conclusion</p> <p>The ICF can help to identify aspects of health which are not being considered. The ICF can help promote further development of adequate outcome measures including activity limitation and participation restrictions by targeting patient centred goals and respecting patients' needs.</p
The R2R3-MYB Transcription Factor Gene Family in Maize
MYB proteins comprise a large family of plant transcription factors, members of which perform a variety of functions in plant biological processes. To date, no genome-wide characterization of this gene family has been conducted in maize (Zea mays). In the present study, we performed a comprehensive computational analysis, to yield a complete overview of the R2R3-MYB gene family in maize, including the phylogeny, expression patterns, and also its structural and functional characteristics. The MYB gene structure in maize and Arabidopsis were highly conserved, indicating that they were originally compact in size. Subgroup-specific conserved motifs outside the MYB domain may reflect functional conservation. The genome distribution strongly supports the hypothesis that segmental and tandem duplication contribute to the expansion of maize MYB genes. We also performed an updated and comprehensive classification of the R2R3-MYB gene families in maize and other plant species. The result revealed that the functions were conserved between maize MYB genes and their putative orthologs, demonstrating the origin and evolutionary diversification of plant MYB genes. Species-specific groups/subgroups may evolve or be lost during evolution, resulting in functional divergence. Expression profile study indicated that maize R2R3-MYB genes exhibit a variety of expression patterns, suggesting diverse functions. Furthermore, computational prediction potential targets of maize microRNAs (miRNAs) revealed that miR159, miR319, and miR160 may be implicated in regulating maize R2R3-MYB genes, suggesting roles of these miRNAs in post-transcriptional regulation and transcription networks. Our comparative analysis of R2R3-MYB genes in maize confirm and extend the sequence and functional characteristics of this gene family, and will facilitate future functional analysis of the MYB gene family in maize
Fruit-Surface Flavonoid Accumulation in Tomato Is Controlled by a SlMYB12-Regulated Transcriptional Network
The cuticle covering plants' aerial surfaces is a unique structure that plays a key role in organ development and protection against diverse stress conditions. A detailed analysis of the tomato colorless-peel y mutant was carried out in the framework of studying the outer surface of reproductive organs. The y mutant peel lacks the yellow flavonoid pigment naringenin chalcone, which has been suggested to influence the characteristics and function of the cuticular layer. Large-scale metabolic and transcript profiling revealed broad effects on both primary and secondary metabolism, related mostly to the biosynthesis of phenylpropanoids, particularly flavonoids. These were not restricted to the fruit or to a specific stage of its development and indicated that the y mutant phenotype is due to a mutation in a regulatory gene. Indeed, expression analyses specified three R2R3-MYBâtype transcription factors that were significantly down-regulated in the y mutant fruit peel. One of these, SlMYB12, was mapped to the genomic region on tomato chromosome 1 previously shown to harbor the y mutation. Identification of an additional mutant allele that co-segregates with the colorless-peel trait, specific down-regulation of SlMYB12 and rescue of the y phenotype by overexpression of SlMYB12 on the mutant background, confirmed that a lesion in this regulator underlies the y phenotype. Hence, this work provides novel insight to the study of fleshy fruit cuticular structure and paves the way for the elucidation of the regulatory network that controls flavonoid accumulation in tomato fruit cuticle
Planck 2013 results. XX. Cosmology from Sunyaev-Zeldovich cluster counts
We present constraints on cosmological parameters using number counts as a
function of redshift for a sub-sample of 189 galaxy clusters from the Planck SZ
(PSZ) catalogue. The PSZ is selected through the signature of the
Sunyaev--Zeldovich (SZ) effect, and the sub-sample used here has a
signal-to-noise threshold of seven, with each object confirmed as a cluster and
all but one with a redshift estimate. We discuss the completeness of the sample
and our construction of a likelihood analysis. Using a relation between mass
and SZ signal calibrated to X-ray measurements, we derive constraints
on the power spectrum amplitude and matter density parameter
in a flat CDM model. We test the robustness of
our estimates and find that possible biases in the -- relation and the
halo mass function are larger than the statistical uncertainties from the
cluster sample. Assuming the X-ray determined mass to be biased low relative to
the true mass by between zero and 30%, motivated by comparison of the observed
mass scaling relations to those from a set of numerical simulations, we find
that , , and
. The value of
is degenerate with the mass bias; if the latter is fixed to a value
of 20% we find and a
tighter one-dimensional range . We find that the larger
values of and preferred by Planck's
measurements of the primary CMB anisotropies can be accommodated by a mass bias
of about 40%. Alternatively, consistency with the primary CMB constraints can
be achieved by inclusion of processes that suppress power on small scales
relative to the CDM model, such as a component of massive neutrinos
(abridged).Comment: 20 pages, accepted for publication by A&
Planck 2015 results. XXVII. The second Planck catalogue of Sunyaev-Zeldovich sources
We present the all-sky Planck catalogue of Sunyaev-Zeldovich (SZ) sources detected from the 29 month full-mission data. The catalogue (PSZ2) is the largest SZ-selected sample of galaxy clusters yet produced and the deepest systematic all-sky surveyof galaxy clusters. It contains 1653 detections, of which 1203 are confirmed clusters with identified counterparts in external data sets, and is the first SZ-selected cluster survey containing >103 confirmed clusters. We present a detailed analysis of the survey selection function in terms of its completeness and statistical reliability, placing a lower limit of 83% on the purity. Using simulations, we find that the estimates of the SZ strength parameter Y5R500are robust to pressure-profile variation and beam systematics, but accurate conversion to Y500 requires the use of prior information on the cluster extent. We describe the multi-wavelength search for counterparts in ancillary data, which makes use of radio, microwave, infra-red, optical, and X-ray data sets, and which places emphasis on the robustness of the counterpart match. We discuss the physical properties of the new sample and identify a population of low-redshift X-ray under-luminous clusters revealed by SZ selection. These objects appear in optical and SZ surveys with consistent properties for their mass, but are almost absent from ROSAT X-ray selected samples
Planck 2013 results. XXIX. Planck catalogue of Sunyaev-Zeldovich sources
We describe the all-sky Planck catalogue of clusters and cluster candidates derived from Sunyaev-Zeldovich (SZ) effect detections using the first 15.5 months of Planck satellite observations. The catalogue contains 1227 entries, making it over six times the size of the Planck Early SZ (ESZ) sample and the largest SZ-selected catalogue to date. It contains 861 confirmed clusters, of which 178 have been confirmed as clusters, mostly through follow-up observations, and a further 683 are previously-known clusters. The remaining 366 have the status of cluster candidates, and we divide them into three classes according to the quality of evidence that they are likely to be true clusters. The Planck SZ catalogue is the deepest all-sky cluster catalogue, with redshifts up to about one, and spans the broadest cluster mass range from (0.1 to 1.6) Ă 1015 MĂąĆ âą. Confirmation of cluster candidates through comparison with existing surveys or cluster catalogues is extensively described, as is the statistical characterization of the catalogue in terms of completeness and statistical reliability. The outputs of the validation process are provided as additional information. This gives, in particular, an ensemble of 813 cluster redshifts, and for all these Planck clusters we also include a mass estimated from a newly-proposed SZ-mass proxy. A refined measure of the SZ Compton parameter for the clusters with X-ray counter-parts is provided, as is an X-ray flux for all the Planck clusters not previously detected in X-ray surveys.The development of Planck has been supported by: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MICINN and JA (Spain); Tekes, AoF and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and PRACE (EU).Peer Reviewe
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