107 research outputs found
The UV colours of high-redshift early-type galaxies: evidence for recent star formation and stellar mass assembly over the last 8 billion years
We combine deep UBVRIzJK photometry from the Multiwavelength Survey by
Yale-Chile (MUSYC) with redshifts from the COMBO-17 survey to perform a
large-scale study of the rest-frame ultraviolet (UV) properties of 674
high-redshift (0.5<z<1) early-type galaxies, drawn from the Extended Chandra
Deep Field South (E-CDFS). Galaxy morphologies are determined through visual
inspection of Hubble Space Telescope (HST) images taken from the GEMS survey.
We harness the sensitivity of the UV to young (<1 Gyr old) stars to quantify
the recent star formation history of early-type galaxies across a range of
luminosities (-23.5 < M(V) < -18). Comparisons to simple stellar populations
forming at high redshift indicate that only ~1.1 percent of early-types in this
sample are consistent with purely passive ageing since z=2. Parametrising the
recent star formation (RSF) in terms of the mass fraction of stars less than a
Gyr old, we find that the early-type population as a whole shows a typical RSF
between 5 and 13% in the redshift range 0.5<z<1. Early-types on the UV red
sequence show RSF values less than 5% while the reddest early-types are
virtually quiescent with RSF values of ~1%. We find compelling evidence that
early-types of all luminosities form stars over the lifetime of the Universe,
although the bulk of their star formation is already complete at high redshift.
This tail-end of star formation is measurable and not negligible, with luminous
(-23<M(V)<-20.5) early-types potentially forming 10-15% of their mass since
z=1, with their less luminous (M(V)>-20.5) counterparts potentially forming
30-60 percent of their mass in the same redshift range. (abridged)Comment: Submitted to MNRA
Newborn spheroids at high redshift: when and how did the dominant, old stars in today's massive galaxies form?
We study ~330 massive (M* > 10^9.5 MSun), newborn spheroidal galaxies (SGs)
around the epoch of peak star formation (1<z<3), to explore the high-redshift
origin of SGs and gain insight into when and how the old stellar populations
that dominate today's Universe formed. The sample is drawn from the HST/WFC3
Early-Release Science programme, which provides deep 10-filter (0.2 - 1.7
micron) HST imaging over a third of the GOODS-South field. We find that the
star formation episodes that built the SGs likely peaked in the redshift range
2<z<5 (with a median of z~3) and have decay timescales shorter than ~1.5 Gyr.
Starburst timescales and ages show no trend with stellar mass in the range
10^9.5 < M* < 10^10.5 MSun. However, the timescales show increased scatter
towards lower values ( 10^10.5 MSun, and an age trend becomes
evident in this mass regime: SGs with M* > 10^11.5 MSun are ~2 Gyrs older than
their counterparts with M* < 10^10.5 MSun. Nevertheless, a smooth downsizing
trend with galaxy mass is not observed, and the large scatter in starburst ages
indicate that SGs are not a particularly coeval population. Around half of the
blue SGs appear not to drive their star formation via major mergers, and those
that have experienced a recent major merger, show only modest enhancements
(~40%) in their specific star formation rates. Our empirical study indicates
that processes other than major mergers (e.g. violent disk instability driven
by cold streams and/or minor mergers) likely play a dominant role in building
SGs, and creating a significant fraction of the old stellar populations that
dominate today's Universe.Comment: MNRAS in pres
Risk management to prioritise the eradication of new and emerging invasive non-native species
Robust tools are needed to prioritise the management of invasive non-native species (INNS). Risk assessment is commonly used to prioritise INNS, but fails to take into account the feasibility of management. Risk management provides a structured evaluation of management options, but has received little attention to date. We present a risk management scheme to assess the feasibility of eradicating INNS that can be used, in conjunction with existing risk assessment schemes, to support prioritisation. The Non-Native Risk Management scheme (NNRM) can be applied to any predefined area and any taxa. It uses semi-quantitative response and confidence scores to assess seven key criteria: Effectiveness, Practicality, Cost, Impact, Acceptability, Window of opportunity and Likelihood of re-invasion. Scores are elicited using expert judgement, supported by available evidence, and consensus-building methods. We applied the NNRM to forty-one INNS that threaten Great Britain (GB). Thirty-three experts provided scores, with overall feasibility of eradication assessed as âvery highâ (8 species), âhighâ (6), âmediumâ (8), âlowâ (10) and âvery lowâ (9). The feasibility of eradicating terrestrial species was higher than aquatic species. Lotic freshwater and marine species scored particularly low. Combining risk management and existing risk assessment scores identified six established species as priorities for eradication. A further six species that are not yet established were identified as priorities for eradication on arrival as part of contingency planning. The NNRM is one of the first INNS risk management schemes that can be used with existing risk assessments to prioritise INNS eradication in any area
International Bottom Trawl Survey Working Group (IBTSWG). ICES Scientific Reports, 04:65
The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent bottom trawl surveys in the ICES area in the Northeast Atlantic and the North Sea. These long-term monitoring surveys provide data for stock assessments and facilitate examina-tion of changes in fish distribution and relative abundance. The group also promotes the stand-ardization of fishing gears and methods as well as survey coordination. This report summarizes the national contributions in 2021â2022 and plans for the 2022â2023 surveys coordinated by IBTSWG
The ESO-Spitzer Imaging extragalactic Survey (ESIS) I: WFI B,V,R deep observations of ELAIS-S1 and comparison to Spitzer and GALEX data
The ESO-Spitzer extragalactic Imaging Survey (ESIS) is the optical follow up
of the Spitzer Wide-Area InfraRed Extragalactic (SWIRE) survey in the ELAIS-S1
area. This paper presents B, V, R Wide Field Imager observations of the first
1.5 square degree of the ESIS survey. Data reduction is described including
astrometric calibration, illumination and color corrections, completeness and
photometric accuracy estimates. Number counts and color distributions are
compared to literature observational and theoretical data, including
non-evolutionary, PLE, evolutionary and semi-analytic Lambda-CDM galaxy models,
as well as Milky Way stellar predictions. ESIS data are in good agreement with
previous works and are best reproduced by evolutionary and hierarchical
Lambda-CDM scenarios. The ELAIS-S1 area benefits from extensive follow-up from
X-ray to radio frequencies: some potential uses of the multi-wavelength
observations are illustrated. Optical-Spitzer color-color plots promise to be
very powerful tools to disentangle different classes of sources (e.g. AGNs,
starbursts, quiescent galaxies). Ultraviolet GALEX data are matched to optical
and Spitzer samples, leading to a discussion of galaxy properties in the
UV-to-24 microns color space. The spectral energy distribution of a few
objects, from the X-rays to the far-IR are presented as examples of the
multi-wavelength study of galaxy emission components in different spectral
domains.Comment: Accepted for publication in A&A. 24 pages, quality of some figures
have been degrade
Cosmic evolution of the galaxy mass and luminosity functions by morphological type from multi-wavelength data in the CDF-South
We constrain the evolution of the galaxy mass and luminosity functions from
the analysis of (public) multi-wavelength data in the Chandra Deep Field South
(CDFS) area, obtained from the GOODS and other projects, and including very
deep high-resolution imaging by HST/ACS. Our reference catalogue of faint
high-redshift galaxies, which we have thoroughly tested for completeness and
reliability, comes from a deep (S(3.6micron)>1 microJy) image by IRAC on the
Spitzer Observatory. These imaging data in the field are complemented with
extensive optical spectroscopy by the ESO VLT/FORS2 and VIMOS spectrographs,
while deep K-band VLT/ISAAC imaging is also used to derive further
complementary statistical constraints and to assist the source identification
and SED analysis. We have selected a highly reliable IRAC 3.6micron sub-sample
of 1478 galaxies with S(3.6)>10microJy, 47% of which have spectroscopic
redshift, while for the remaining objects both COMBO-17 and Hyperz are used to
estimate the photometric redshift. This very extensive dataset is exploited to
assess evolutionary effects in the galaxy luminosity and stellar mass
functions, while luminosity/density evolution is further constrained with the
number counts and redshift distributions. The deep ACS imaging allows us to
differentiate these evolutionary paths by morphological type, which our
simulations show to be reliable at least up to z=1.5 for the two main early-
(E/S0) and late-type (Sp/Irr) classes. These data, as well as our direct
estimate of the stellar mass function above M=10^(10)M_sun for the spheroidal
subclass, consistently evidence a progressive dearth of such objects to occur
starting at z=0.7, paralleled by an increase in luminosity. (abridged)Comment: paper accepted for publication in A&
The Gene Ontology resource: enriching a GOld mine
The Gene Ontology Consortium (GOC) provides the most comprehensive resource currently available for computable knowledge regarding the functions of genes and gene products. Here, we report the advances of the consortium over the past two years. The new GO-CAM annotation framework was notably improved, and we formalized the model with a computational schema to check and validate the rapidly increasing repository of 2838 GO-CAMs. In addition, we describe the impacts of several collaborations to refine GO and report a 10% increase in the number of GO annotations, a 25% increase in annotated gene products, and over 9,400 new scientific articles annotated. As the project matures, we continue our efforts to review older annotations in light of newer findings, and, to maintain consistency with other ontologies. As a result, 20 000 annotations derived from experimental data were reviewed, corresponding to 2.5% of experimental GO annotations. The website (http://geneontology.org) was redesigned for quick access to documentation, downloads and tools. To maintain an accurate resource and support traceability and reproducibility, we have made available a historical archive covering the past 15 years of GO data with a consistent format and file structure for both the ontology and annotations
Ultraluminous Infrared Galaxies
Ever since their discovery in the 1970's, UltraLuminous InfraRed Galaxies
(ULIRGs; classically Lir>10^12Lsun) have fascinated astronomers with their
immense luminosities, and frustrated them due to their singularly opaque
nature, almost in equal measure. Over the last decade, however, comprehensive
observations from the X-ray through to the radio have produced a consensus
picture of local ULIRGs, showing that they are mergers between gas rich
galaxies, where the interaction triggers some combination of dust-enshrouded
starburst and AGN activity, with the starburst usually dominating. Very recent
results have thrown ULIRGs even further to the fore. Originally they were
thought of as little more than a local oddity, but the latest IR surveys have
shown that ULIRGs are vastly more numerous at high redshift, and tantalizing
suggestions of physical differences between high and low redshift ULIRGs hint
at differences in their formation modes and local environment. In this review
we look at recent progress on understanding the physics and evolution of local
ULIRGs, the contribution of high redshift ULIRGs to the cosmic infrared
background and the global history of star formation, and the role of ULIRGs as
diagnostics of the formation of massive galaxies and large-scale structures.Comment: Review article, published in "Astrophysics Update 2 - topical and
timely reviews on astronomy and astrophysics". Ed. John W. Mason.
Springer/Praxis books. ISBN: 3-540-30312-X. 53 pages, 5 figures. Higher
quality figures available on reques
Carboplatin in BRCA1/2-mutated and triple-negative breast cancer BRCAness subgroups: the TNT Trial
Germline mutations in BRCA1/2 predispose individuals to breast cancer (termed germline-mutated BRCA1/2 breast cancer, gBRCA-BC) by impairing homologous recombination (HR) and causing genomic instability. HR also repairs DNA lesions caused by platinum agents and PARP inhibitors. Triple-negative breast cancers (TNBCs) harbor subpopulations with BRCA1/2 mutations, hypothesized to be especially platinum-sensitive. Cancers in putative âBRCAnessâ subgroupsâtumors with BRCA1 methylation; low levels of BRCA1 mRNA (BRCA1 mRNA-low); or mutational signatures for HR deficiency and those with basal phenotypesâmay also be sensitive to platinum. We assessed the efficacy of carboplatin and another mechanistically distinct therapy, docetaxel, in a phase 3 trial in subjects with unselected advanced TNBC. A prespecified protocol enabled biomarkerâtreatment interaction analyses in gBRCA-BC and BRCAness subgroups. The primary endpoint was objective response rate (ORR). In the unselected population (376 subjects; 188 carboplatin, 188 docetaxel), carboplatin was not more active than docetaxel (ORR, 31.4% versus 34.0%, respectively; Pâ=â0.66). In contrast, in subjects with gBRCA-BC, carboplatin had double the ORR of docetaxel (68% versus 33%, respectively; biomarker, treatment interaction Pâ=â0.01). Such benefit was not observed for subjects with BRCA1 methylation, BRCA1 mRNA-low tumors or a high score in a Myriad HRD assay. Significant interaction between treatment and the basal-like subtype was driven by high docetaxel response in the nonbasal subgroup. We conclude that patients with advanced TNBC benefit from characterization of BRCA1/2 mutations, but not BRCA1 methylation or Myriad HRD analyses, to inform choices on platinum-based chemotherapy. Additionally, gene expression analysis of basal-like cancers may also influence treatment selection
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