523 research outputs found
The Colors of Dwarf Elliptical Galaxy Globular Cluster Systems, Nuclei and Stellar Halos
We present the results of a Hubble Space Telescope WFPC2 F555W and F814W
survey of 69 dwarf elliptical galaxies (dEs) in the Virgo and Fornax Clusters
and Leo Group. The colors of the dE globular clusters, nuclei, and
underlying field star populations are used to trace the dE star-formation
histories. We find that the dE globular cluster candidates are as blue as the
metal-poor globular clusters of the Milky Way. The observed correlation of the
dE globular cluster systems' color with the luminosity of the host dE is
strong evidence that the globular clusters were formed within the the halos of
dEs and do not have a pre-galactic origin. Assuming the majority of dE clusters
are old, the mean globular cluster color- host galaxy luminosity correlation
implies a cluster metallicity galaxy luminosity relation of , which is significantly shallower than the field star
metallicity - host galaxy luminosity relationship observed in Local Group
dwarfs (). The dE stellar envelopes are
magnitudes redder in than their globular clusters and nuclei. This color
offset implies separate star-formation episodes within the dEs for the clusters
and field stars, while the very blue colors of two dE nuclei trace a third
star-formation event in those dEs less than a Gyr ago.Comment: 39 pages, including 5 tables and 10 figures; accepted by the
Astrophysical Journa
Telehealth and Mobile Health Applied To IntegratedBehavioral Care: OpportunitiesFor Progress In New Hampshire
This paper is an accompanying document to a webinar delivered on May 16, 2017, for the New Hampshire Citizens Health Initiative (Initiative). As integrated behavioral health efforts in New Hampshire gain traction, clinicians, administrators, payers, and policy makers are looking for additional efficiencies in delivering high quality healthcare. Telehealth and mobile health (mHealth) have the opportunity to help achieve this while delivering a robust, empowered patient experience.
The promise of video-based technology was first made in 1964 as Bell Telephone shared its Picturephone® with the world. This was the first device with audio and video delivered in an integrated technology platform. Fast-forward to today with Skype, FaceTime, and webinar tools being ubiquitous in our personal and business lives, but often slow to be adopted in the delivery of medicine.
Combining technology-savvy consumers with New Hampshire’s high rate of electronic health record (EHR) technology adoption, a fairly robust telecommunications infrastructure, and a predominately rural setting, there is strong foundation for telehealth and mHealth expansion in New Hampshire’s integrated health continuum
A search for ultra-compact dwarf galaxies in the Centaurus galaxy cluster
Aim: To extend the investigations of ultra-compact dwarf galaxies (UCDs)
beyond the well studied Fornax and Virgo clusters. Methods: We measured
spectroscopic redshifts of about 400 compact object candidates with 19.2 < V <
22.4 mag in the central region of the Centaurus galaxy cluster (d=43Mpc), using
VIMOS@VLT. The luminosity range of the candidates covers that of bright
globular clusters (GCs) and of UCDs in Fornax and Virgo. Results: We confirm
the cluster membership of 27 compact objects, covering an absolute magnitude
range -12.2 < M_V < -10.9 mag. We do not find counterparts to the two very
large and bright UCDs in Fornax and Virgo with M_V=-13.5 mag, possibly due to
survey incompleteness. The compact objects' distribution in magnitude and space
is consistent with that of the GC population. Their kinematics and spatial
distribution associate them to the central galaxies rather than to the overall
cluster potential. The compact objects have a mean metallicity consistent with
that of the metal-rich globular cluster sub-population. Compact objects with
high S/N spectra exhibit solar [alpha/Fe] abundances, consistent with typical
dwarf elliptical galaxy values and unlike galactic bulge globular clusters. HST
based size estimates for a sub-sample of eight compact objects reveal the
existence of one very large object with half-light radius r_h around 30 pc,
having M_V=-11.6 mag (~10^7 M_sun). This source shows super-solar [alpha/Fe]
abundances. Seven further sources are only marginally larger than typical GCs
with r_h in the range 4 to 10 pc. Conclusions: We consider the largest compact
object found to be the only bona-fide UCD detected in our study. In order to
improve our understanding of UCDs in Centaurus, a significant increase of our
survey completeness is necessary.Comment: 11 pages, 12 figures, accepted for publication in A&
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
The Morphology of Galaxies in the Baryon Oscillation Spectroscopic Survey
We study the morphology of luminous and massive galaxies at 0.3<z<0.7
targeted in the Baryon Oscillation Spectroscopic Survey (BOSS) using publicly
available Hubble Space Telescope imaging from COSMOS. Our sample (240 objects)
provides a unique opportunity to check the visual morphology of these galaxies
which were targeted based solely on stellar population modelling. We find that
the majority (74+/-6%) possess an early-type morphology (elliptical or S0),
while the remainder have a late-type morphology. This is as expected from the
goals of the BOSS target selection which aimed to predominantly select slowly
evolving galaxies, for use as cosmological probes, while still obtaining a fair
fraction of actively star forming galaxies for galaxy evolution studies. We
show that a colour cut of (g-i)>2.35 selects a sub-sample of BOSS galaxies with
90% early-type morphology - more comparable to the earlier Luminous Red Galaxy
(LRG) samples of SDSS-I/II. The remaining 10% of galaxies above this cut have a
late-type morphology and may be analogous to the "passive spirals" found at
lower redshift. We find that 23+/-4% of the early-type galaxies are unresolved
multiple systems in the SDSS imaging. We estimate that at least 50% of these
are real associations (not projection effects) and may represent a significant
"dry merger" fraction. We study the SDSS pipeline sizes of BOSS galaxies which
we find to be systematically larger (by 40%) than those measured from HST
images, and provide a statistical correction for the difference. These details
of the BOSS galaxies will help users of the data fine-tune their selection
criteria, dependent on their science applications. For example, the main goal
of BOSS is to measure the cosmic distance scale and expansion rate of the
Universe to percent-level precision - a point where systematic effects due to
the details of target selection may become important.Comment: 18 pages, 11 figures; v2 as accepted by MNRA
Galaxy Assembly Bias on the Red Sequence
Using samples drawn from the Sloan Digital Sky Survey, we study the
relationship between local galaxy density and the properties of galaxies on the
red sequence. After removing the mean dependence of average overdensity (or
"environment") on color and luminosity, we find that there remains a strong
residual trend between luminosity-weighted mean stellar age and environment,
such that galaxies with older stellar populations favor regions of higher
overdensity relative to galaxies of like color and luminosity (and hence of
like stellar mass). Even when excluding galaxies with recent star-formation
activity (i.e., younger mean stellar ages) from the sample, we still find a
highly significant correlation between stellar age and environment at fixed
stellar mass. This residual age-density relation provides direct evidence for
an assembly bias on the red sequence such that galaxies in higher-density
regions formed earlier than galaxies of similar mass in lower-density
environments. We discuss these results in the context of the age-metallicity
degeneracy and in comparison to previous studies at low and intermediate
redshift. Finally, we consider the potential role of assembly bias in
explaining recent results regarding the evolution of post-starburst (or
post-quenching) galaxies and the environmental dependence of the type Ia
supernova rate.Comment: Accepted for publication in MNRA
The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs
The Coma cluster was the target of a HST-ACS Treasury program designed for
deep imaging in the F475W and F814W passbands. Although our survey was
interrupted by the ACS instrument failure in 2007, the partially completed
survey still covers ~50% of the core high-density region in Coma. Observations
were performed for 25 fields that extend over a wide range of cluster-centric
radii (~1.75 Mpc) with a total coverage area of 274 arcmin^2. The majority of
the fields are located near the core region of Coma (19/25 pointings) with six
additional fields in the south-west region of the cluster. In this paper we
present reprocessed images and SExtractor source catalogs for our survey
fields, including a detailed description of the methodology used for object
detection and photometry, the subtraction of bright galaxies to measure faint
underlying objects, and the use of simulations to assess the photometric
accuracy and completeness of our catalogs. We also use simulations to perform
aperture corrections for the SExtractor Kron magnitudes based only on the
measured source flux and half-light radius. We have performed photometry for
~73,000 unique objects; one-half of our detections are brighter than the
10-sigma point-source detection limit at F814W=25.8 mag (AB). The slight
majority of objects (60%) are unresolved or only marginally resolved by ACS. We
estimate that Coma members are 5-10% of all source detections, which consist of
a large population of unresolved objects (primarily GCs but also UCDs) and a
wide variety of extended galaxies from a cD galaxy to dwarf LSB galaxies. The
red sequence of Coma member galaxies has a constant slope and dispersion across
9 magnitudes (-21<M_F814W<-13). The initial data release for the HST-ACS Coma
Treasury program was made available to the public in 2008 August. The images
and catalogs described in this study relate to our second data release.Comment: Accepted for publication in ApJS. A high-resolution version is
available at http://archdev.stsci.edu/pub/hlsp/coma/release2/PaperII.pd
Internet-distributed television research: a provocation
From Netflix and Hulu to iPlayer and iQiyi, the rapid growth of internet-distributed television services worldwide presents both opportunities and challenges for media industry scholars. Which business models are succeeding in different countries, and why? What frameworks help us explain and talk about television amid such a variety of industrial practices? This article provides a critical overview of the emerging research landscape and suggests future lines of inquiry. We offer seven provocations regarding specific issues in internet-distributed television research-theory, comparison, market definition, historiography, regulation, user experience, and industry transformation
Rucaparib maintenance treatment for recurrent ovarian carcinoma after response to platinum therapy (ARIEL3): a randomised, double-blind, placebo-controlled, phase 3 trial
Background:
Rucaparib, a poly(ADP-ribose) polymerase inhibitor, has anticancer activity in recurrent ovarian carcinoma harbouring a BRCA mutation or high percentage of genome-wide loss of heterozygosity. In this trial we assessed rucaparib versus placebo after response to second-line or later platinum-based chemotherapy in patients with high-grade, recurrent, platinum-sensitive ovarian carcinoma.
Methods:
In this randomised, double-blind, placebo-controlled, phase 3 trial, we recruited patients from 87 hospitals and cancer centres across 11 countries. Eligible patients were aged 18 years or older, had a platinum-sensitive, high-grade serous or endometrioid ovarian, primary peritoneal, or fallopian tube carcinoma, had received at least two previous platinum-based chemotherapy regimens, had achieved complete or partial response to their last platinum-based regimen, had a cancer antigen 125 concentration of less than the upper limit of normal, had a performance status of 0–1, and had adequate organ function. Patients were ineligible if they had symptomatic or untreated central nervous system metastases, had received anticancer therapy 14 days or fewer before starting the study, or had received previous treatment with a poly(ADP-ribose) polymerase inhibitor. We randomly allocated patients 2:1 to receive oral rucaparib 600 mg twice daily or placebo in 28 day cycles using a computer-generated sequence (block size of six, stratified by homologous recombination repair gene mutation status, progression-free interval after the penultimate platinum-based regimen, and best response to the most recent platinum-based regimen). Patients, investigators, site staff, assessors, and the funder were masked to assignments. The primary outcome was investigator-assessed progression-free survival evaluated with use of an ordered step-down procedure for three nested cohorts: patients with BRCA mutations (carcinoma associated with deleterious germline or somatic BRCA mutations), patients with homologous recombination deficiencies (BRCA mutant or BRCA wild-type and high loss of heterozygosity), and the intention-to-treat population, assessed at screening and every 12 weeks thereafter. This trial is registered with ClinicalTrials.gov, number NCT01968213; enrolment is complete.
Findings:
Between April 7, 2014, and July 19, 2016, we randomly allocated 564 patients: 375 (66%) to rucaparib and 189 (34%) to placebo. Median progression-free survival in patients with a BRCA-mutant carcinoma was 16·6 months (95% CI 13·4–22·9; 130 [35%] patients) in the rucaparib group versus 5·4 months (3·4–6·7; 66 [35%] patients) in the placebo group (hazard ratio 0·23 [95% CI 0·16–0·34]; p<0·0001). In patients with a homologous recombination deficient carcinoma (236 [63%] vs 118 [62%]), it was 13·6 months (10·9–16·2) versus 5·4 months (5·1–5·6; 0·32 [0·24–0·42]; p<0·0001). In the intention-to-treat population, it was 10·8 months (8·3–11·4) versus 5·4 months (5·3–5·5; 0·36 [0·30–0·45]; p<0·0001). Treatment-emergent adverse events of grade 3 or higher in the safety population (372 [99%] patients in the rucaparib group vs 189 [100%] in the placebo group) were reported in 209 (56%) patients in the rucaparib group versus 28 (15%) in the placebo group, the most common of which were anaemia or decreased haemoglobin concentration (70 [19%] vs one [1%]) and increased alanine or aspartate aminotransferase concentration (39 [10%] vs none).
Interpretation:
Across all primary analysis groups, rucaparib significantly improved progression-free survival in patients with platinum-sensitive ovarian cancer who had achieved a response to platinum-based chemotherapy. ARIEL3 provides further evidence that use of a poly(ADP-ribose) polymerase inhibitor in the maintenance treatment setting versus placebo could be considered a new standard of care for women with platinum-sensitive ovarian cancer following a complete or partial response to second-line or later platinum-based chemotherapy.
Funding:
Clovis Oncology
- …
