90 research outputs found
The Nearby and Extremely Metal-Poor Galaxy CGCG 269-049
We present Hubble Space Telescope (HST) and Spitzer Space Telescope images
and photometry of the extremely metal-poor (Z = 0.03 Z_sol) blue dwarf galaxy
CGCG 269-049. The HST images reveal a large population of red giant and
asymptotic giant branch stars, ruling out the possibility that the galaxy has
recently formed. From the magnitude of the tip of the red giant branch, we
measure a distance to CGCG 269-049 of only 4.9 +/- 0.4 Mpc. The spectral energy
distribution of the galaxy between ~3.6 - 70 microns is also best fitted by
emission from predominantly ~10 Gyr old stars, with a component of thermal dust
emission having a temperature of 52 +/- 10 K. The HST and Spitzer photometry
indicate that more than 60% of CGCG 269-049's stellar mass consists of stars
~10 Gyr old, similar to other local blue dwarf galaxies. Our HST H-alpha image
shows no evidence of a supernova-driven outflow that could be removing metals
from the galaxy, nor do we find evidence that such outflows occurred in the
past. Taken together with CGCG 269-049's large ratio of neutral hydrogen mass
to stellar mass (~10), these results are consistent with recent simulations in
which the metal deficiency of local dwarf galaxies results mainly from
inefficient star formation, rather than youth or the escape of supernova
ejecta.Comment: 35 Pages, 7 Figures, accepted for publication in ApJ; new version
corrects errors in Table 1, Figure 3, and related calculations in tex
Enteral Vancomycin to Eliminate MRSA Carriership of the Digestive Tract in Critically Ill Patients
Background: Carriership with methicillin resistant Staphylococcus aureus (MRSA) is a risk for the development of secondary infections in critically ill patients. Previous studies suggest that enteral vancomycin is able to eliminate enteral carriership with MRSA. Data on individual effects of this treatment are lacking. Methods: Retrospective analysis of a database containing 15 year data of consecutive patients from a mixed medical-(cardio)surgical 18 bedded intensive care unit was conducted. All consecutive critically ill patients with enteral MRSA carriership detected in throat and/or rectal samples were collected. We analyzed those with follow-up cultures to determine the success rate of enteral vancomycin. Topical application of 2% vancomycin in a sticky oral paste was performed combined with a vancomycin solution of 500 mg four times daily in the nasogastric tube. This treatment was added to a regimen of selective digestive tract decontamination (SDD) to prevent ICU acquired infection. Results: Thirteen patients were included. The mean age was 65 years and the median APACHE II score was 21. MRSA was present in the throat in 8 patients and in both throat and rectum in 5 patients. In all patients MRSA was successfully eliminated from both throat and rectum, which took 2–11 days with a median duration until decontamination of 4 days. Secondary infections with MRSA did not occur. Conclusions: Topical treatment with vancomycin in a 2% sticky oral paste four times daily in the nasogastric tube was effective in all patients in the elimination of MRSA and prevented secondary MRSA infections
Star Clusters in the Nearby Late-Type Galaxy NGC 1311
Ultraviolet, optical and near infrared images of the nearby (D ~ 5.5 Mpc) SBm
galaxy NGC 1311, obtained with the Hubble Space Telescope, reveal a small
population of 13 candidate star clusters. We identify candidate star clusters
based on a combination of their luminosity, extent and spectral energy
distribution. The masses of the cluster candidates range from ~1000 up to
~100000 Solar masses, and show a strong positive trend of larger mass with
increasing with cluster age. Such a trend follows from the fading and
dissolution of old, low-mass clusters, and the lack of any young super star
clusters of the sort often formed in strong starbursts. The cluster age
distribution is consistent with a bursting mode of cluster formation, with
active episodes of age ~10 Myr, ~100 Myr and ~1 Gyr. The ranges of age and mass
we probe are consistent with those of the star clusters found in quiescent
Local Group dwarf galaxies.Comment: 21 pages, 11 figures, accepted by A
Hubble Space Telescope WFC3 Early Release Science: Emission-Line Galaxies from Infrared Grism Observations
We present grism spectra of emission-line galaxies (ELGs) from 0.6-1.6
microns from the Wide Field Camera 3 on the Hubble Space Telescope. These new
infrared grism data augment previous optical Advanced Camera for Surveys G800L
0.6-0.95 micron grism data in GOODS-South from the PEARS program, extending the
wavelength covereage well past the G800L red cutoff. The ERS grism field was
observed at a depth of 2 orbits per grism, yielding spectra of hundreds of
faint objects, a subset of which are presented here. ELGs are studied via the
Ha, [OIII], and [OII] emission lines detected in the redshift ranges 0.2<z<1.4,
1.2<z<2.2 and 2.0<z<3.3 respectively in the G102 (0.8-1.1 microns; R~210) and
G141 (1.1-1.6 microns; R~130) grisms. The higher spectral resolution afforded
by the WFC3 grisms also reveals emission lines not detectable with the G800L
grism (e.g., [SII] and [SIII] lines). From these relatively shallow
observations, line luminosities, star-formation rates, and grism spectroscopic
redshifts are determined for a total of 48 ELGs to m(AB)~25 mag. Seventeen
GOODS-South galaxies that previously only had photometric redshifts now have
new grism-spectroscopic redshifts, in some cases with large corrections to the
photometric redshifts (Delta(z)~0.3-0.5). Additionally, one galaxy had no
previously-measured redshift but now has a secure grism-spectroscopic redshift,
for a total of 18 new GOODS-South spectroscopic redshifts. The faintest source
in our sample has a magnitude m(AB)=26.9 mag. The ERS grism data also reflect
the expected trend of lower specific star formation rates for the highest mass
galaxies in the sample as a function of redshift, consistent with downsizing
and discovered previously from large surveys. These results demonstrate the
remarkable efficiency and capability of the WFC3 NIR grisms for measuring
galaxy properties to faint magnitudes and redshifts to z>2.Comment: Accepted for publication in AJ. Updated to include referee comments.
Updated sample using improved reduction contains 23 new galaxies (Table 1;
Figures 2 & 3
Simulated effect of pneumococcal vaccination in the Netherlands on existing rules constructed in a non-vaccinated cohort predicting sequelae after bacterial meningitis
BACKGROUND: Previously two prediction rules identifying children at risk of hearing loss and academic or behavioral limitations after bacterial meningitis were developed. Streptococcus pneumoniae as causative pathogen was an important risk factor in both. Since 2006 Dutch children receive seven-valent conjugate vaccination against S. pneumoniae. The presumed effect of vaccination was simulated by excluding all children infected by S. pneumoniae with the serotypes included in the vaccine, from both previous collected cohorts (between 1990-1995). METHODS: Children infected by one of the vaccine serotypes were excluded from both original cohorts (hearing loss: 70 of 628 children; academic or behavioral limitations: 26 of 182 children). All identified risk factors were included in multivariate logistic regression models. The discriminative ability of both new models was calculated. RESULTS: The same risk factors as in the original models were significant. The discriminative ability of the original hearing loss model was 0.84 and of the new model 0.87. In the academic or behavioral limitations model it was 0.83 and 0.84 respectively. CONCLUSION: It can be assumed that the prediction rules will also be applicable on a vaccinated population. However, vaccination does not provide 100% coverage and evidence is available that serotype replacement will occur. The impact of vaccination on serotype replacement needs to be investigated, and the prediction rules must be validated externally
An HST Survey of the mid-UV Morphology of Nearby Galaxies
(Abbreviated) We present an imaging survey of 37 nearby galaxies observed
with HST/WFPC2 in the mid-UV F300W filter and in F814W. 11 galaxies were also
imaged in F255W. These galaxies were selected to be detectable with WFPC2 in
one orbit, and cover a wide range of Hubble types and inclinations. The mid-UV
spans the gap between our groundbased optical/NIR images and far-UV images
available from the Astro/UIT missions. Our first qualitative results are:
(1) Early-type galaxies show a significant decrease in surface brightness
going from the red to the mid-UV, and in some cases the presence of dust lanes.
Some galaxies would be classified different when viewed in the mid-UV, some
become dominated by a blue nuclear feature or point source.
(2) Half of the mid-type spiral and star-forming galaxies appear as a later
morphological type in the mid-UV, as Astro/UIT also found in the far-UV. Some-
times these differences are dramatic. The mid-UV images show a considerable
range in the scale and surface brightness of individual star-forming regions.
Almost all mid-type spirals have their small bulges bi-sected by a dust-lane.
(3) Most of the heterogeneous subset of late-type, irregular, peculiar, and
merging galaxies display F300W morphologies that are similar to those seen in
F814W, but with differences due to recognizable dust features absorbing the
bluer light, and due to UV-bright hot stars, star-clusters, and star-forming
ridges.
In the rest-frame mid-UV, early- to mid-type galaxies are more likely to be
misclassified as later types than vice versa. This morphological K-correction
explains only part of the excess faint blue galaxies seen in deep HST fields.Comment: 30 pages, LateX (AASTeX5.0), 2 figures and 3 tables included, mid-UV
atlas and pan-chromatic atlas provided as 63 JPG figures. Full resolution PS
version (~100Mb) available upon request. Accepted for publication in ApJ
Limits to Rest-Frame Ultraviolet Emission From Far-Infrared-Luminous z~6 Quasar Hosts
We report on a Hubble Space Telescope search for rest-frame ultraviolet
emission from the host galaxies of five far-infrared-luminous
quasars and the hot-dust free quasar SDSS J0005-0006. We perform 2D
surface brightness modeling for each quasar using a Markov-Chain Monte-Carlo
estimator, to simultaneously fit and subtract the quasar point source in order
to constrain the underlying host galaxy emission. We measure upper limits for
the quasar host galaxies of mag and mag, corresponding to
stellar masses of . These stellar mass limits are
consistent with the local - relation. Our flux limits
are consistent with those predicted for the UV stellar populations of
host galaxies, but likely in the presence of significant dust
( mag). We also detect a total of up
to 9 potential quasar companion galaxies surrounding five of the six
quasars, separated from the quasars by 1.4''-3.2'', or 8.4-19.4 kpc, which may
be interacting with the quasar hosts. These nearby companion galaxies have UV
absolute magnitudes of -22.1 to -19.9 mag, and UV spectral slopes of
-2.0 to -0.2, consistent with luminous star-forming galaxies at .
These results suggest that the quasars are in dense environments typical of
luminous galaxies. However, we cannot rule out the possibility that
some of these companions are foreground interlopers. Infrared observations with
the James Webb Space Telescope will be needed to detect the quasar
host galaxies and better constrain their stellar mass and dust content.Comment: 22 pages, 13 figures. Accepted for publication in Ap
Biological and Clinical Implications of Gene-Expression Profiling in Diffuse Large B-Cell Lymphoma:A Proposal for a Targeted BLYM-777 Consortium Panel as Part of a Multilayered Analytical Approach
Gene-expression profiling (GEP) is used to study the molecular biology of lymphomas. Here, advancing insights from GEP studies in diffuse large B-cell lymphoma (DLBCL) lymphomagenesis are discussed. GEP studies elucidated subtypes based on cell-of-origin principles and profoundly changed the biological understanding of DLBCL with clinical relevance. Studies integrating GEP and next-generation DNA sequencing defined different molecular subtypes of DLBCL entities originating at specific anatomical localizations. With the emergence of high-throughput technologies, the tumor microenvironment (TME) has been recognized as a critical component in DLBCL pathogenesis. TME studies have characterized so-called “lymphoma microenvironments" and “ecotypes”. Despite gained insights, unexplained chemo-refractoriness in DLBCL remains. To further elucidate the complex biology of DLBCL, we propose a novel targeted GEP consortium panel, called BLYM-777. This knowledge-based biology-driven panel includes probes for 777 genes, covering many aspects regarding B-cell lymphomagenesis (f.e., MYC signature, TME, immune surveillance and resistance to CAR T-cell therapy). Regarding lymphomagenesis, upcoming DLBCL studies need to incorporate genomic and transcriptomic approaches with proteomic methods and correlate these multi-omics data with patient characteristics of well-defined and homogeneous cohorts. This multilayered methodology potentially enhances diagnostic classification of DLBCL subtypes, prognostication, and the development of novel targeted therapeutic strategies. Simple Summary: This review summarizes gene-expression profiling insights into the background and origination of diffuse large B-cell lymphomas (DLBCL). To further unravel the molecular biology of these lymphomas, a consortium panel called BLYM-777 was designed including genes important for subtype classifications, genetic pathways, tumor-microenvironment, immune response and resistance to targeted therapies. This review proposes to combine this transcriptomic method with genomics, proteomics, and patient characteristics to facilitate diagnostic classification, prognostication, and the development of new targeted therapeutic strategies in DLBCL
TREASUREHUNT: Transients and Variability Discovered with HST in the JWST North Ecliptic Pole Time-domain Field
The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF) is a >14′ diameter field optimized for multiwavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over three cycles (the “TREASUREHUNT” program), deep images were obtained with the Wide Field Camera on the Advanced Camera for Surveys in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ∼88 arcmin2, with time intervals between individual epochs that range between 1 day and 4+ yr. To a depth of m AB ≃ 29.5 mag (F606W), we present the discovery of 12 transients and 190 variable candidates. For the variable candidates, we demonstrate that Gaussian statistics are applicable and estimate that ∼80 are false positives. The majority of the transients will be supernovae, although at least two are likely quasars. Most variable candidates are active galactic nuclei (AGNs), where we find 0.42% of the general z ≲ 6 field galaxy population to vary at the ∼3σ level. Based on a 5 yr time frame, this translates into a random supernova areal density of up to ∼0.07 transients arcmin−2 (∼245 deg−2) per epoch and a variable AGN areal density of ∼1.25 variables arcmin−2 (∼4500 deg−2) to these depths
Long-Term Outcome of Immediate Versus Postponed" Intervention in Patients With Infected Necrotizing Pancreatitis" (POINTER)" Multicenter Randomized Trial
Objective: To compare the long-term outcomes of immediate drainage versus the postponed-drainage approach in patients with infected necrotizing pancreatitis. Background: In the randomized POINTER trial, patients assigned to the postponed-drainage approach using antibiotic treatment required fewer interventions, as compared with immediate drainage, and over a third were treated without any intervention. Methods: Clinical data of those patients alive after the initial 6-month follow-up were re-evaluated. The primary outcome was a composite of death and major complications. Results: Out of 104 patients, 88 were re-evaluated with a median followup of 51 months. After the initial 6-month follow-up, the primary outcome occurred in 7 of 47 patients (15%) in the immediate-drainage group and 7 of 41 patients (17%) in the postponed-drainage group (RR 0.87, 95% CI 0.33-2.28; P=0.78). Additional drainage procedures were performed in 7 patients (15%) versus 3 patients (7%) (RR 2.03; 95% CI 0.56-7.37; P=0.34). The median number of additional interventions was 0 (IQR 0-0) in both groups (P=0.028). In the total follow-up, the median number of interventions was higher in the immediate-drainage group than in the postponed-drainage group (4 vs. 1, P=0.001). Eventually, 14 of 15 patients (93%) in the postponed-drainage group who were successfully treated in the initial 6-month follow-up with antibiotics and without any intervention remained without intervention. At the end of follow-up, pancreatic function and quality of life were similar. Conclusions: Also, during long-term follow-up, a postponed-drainage approach using antibiotics in patients with infected necrotizing pancreatitis results in fewer interventions as compared with immediate drainage and should therefore be the preferred approach.</p
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