179 research outputs found
Molecular Gas, Dust and Star Formation in Galaxies: II. Dust properties and scalings in \sim\ 1600 nearby galaxies
We aim to characterize the relationship between dust properties. We also aim
to provide equations to estimate accurate dust properties from limited
observational datasets.
We assemble a sample of 1,630 nearby (z<0.1) galaxies-over a large range of
Mstar, SFR - with multi-wavelength observations available from wise, iras,
planck and/or SCUBA. The characterization of dust emission comes from SED
fitting using Draine & Li dust models, which we parametrize using two
components (warm and cold ). The subsample of these galaxies with global
measurements of CO and/or HI are used to explore the molecular and/or atomic
gas content of the galaxies.
The total Lir, Mdust and dust temperature of the cold component (Tc) form a
plane that we refer to as the dust plane. A galaxy's sSFR drives its position
on the dust plane: starburst galaxies show higher Lir, Mdust and Tc compared to
Main Sequence and passive galaxies. Starburst galaxies also show higher
specific Mdust (Mdust/Mstar) and specific Mgas (Mgas/Mstar). The Mdust is more
closely correlated with the total Mgas (atomic plus molecular) than with the
individual components. Our multi wavelength data allows us to define several
equations to estimate Lir, Mdust and Tc from one or two monochromatic
luminosities in the infrared and/or sub-millimeter.
We estimate the dust mass and infrared luminosity from a single monochromatic
luminosity within the R-J tail of the dust emission, with errors of 0.12 and
0.20dex, respectively. These errors are reduced to 0.05 and 0.10 dex,
respectively, if the Tc is used. The Mdust is correlated with the total Mism
(Mism \propto Mdust^0.7). For galaxies with Mstar 8.5<log(Mstar/Msun) < 11.9,
the conversion factor \alpha_850mum shows a large scatter (rms=0.29dex). The SF
mode of a galaxy shows a correlation with both the Mgass and Mdust: high
Mdust/Mstar galaxies are gas-rich and show the highest SFRs.Comment: 24 pages, 28 figures, 6 tables, Accepted for publication in A&
Galaxy pre-processing in substructures around z0.4 galaxy clusters
We present a detailed analysis of galaxy colours in two galaxy clusters at
\mbox{z 0.4}, \mbox{MACS J0416.1-2403} and \mbox{MACS J1206.2-0847},
drawn from the CLASH-VLT survey, to investigate the role of pre-processing in
the quenching of star formation. We estimate the fractions of red and blue
galaxies within the main cluster and the detected substructures and study the
trends of the colour fractions as a function of the projected distance from the
cluster and substructure centres. Our results show that the colours of cluster
and substructure members have consistent spatial distributions. In particular,
the colour fractions of galaxies inside substructures follow the same spatial
trends observed in the main clusters. Additionally, we find that at large
cluster-centric distances \mbox{()} the fraction of blue
galaxies in both the main clusters and in the substructures is always lower
than the average fraction of UVJ-selected star-forming galaxies in the field as
measured in the COSMOS/UltraVista data set. We finally estimate environmental
quenching efficiencies in the clusters and in the substructures and find that
at large distances from the cluster centres, the quenching efficiency of
substructures becomes comparable to the quenching efficiency of clusters. Our
results suggest that pre-processing plays a significant role in the formation
and evolution of passive galaxies in clusters at low redshifts.Comment: Accepted for publication in MNRAS. 28 pages, 14 figures, 20 table
Technical standardization of MIS management of children with pilonidal sinus disease using pediatric endoscopic pilonidal sinus treatment (PEPSiT) and laser epilation
This study aimed to standardize the technique of pediatric endoscopic pilonidal sinus treatment (PEPSiT) associated with laser epilation.
METHODS:
All pediatric patients presenting with acute or chronic pilonidal sinus disease (PSD) who underwent PEPSiT in our institution over a 36-month period (July 2015-July 2018), were included in the study. Pre- and postoperative management, recurrence rate, postoperative pain, hospital stay, analgesic requirements, and patient satisfaction levels were evaluated.
RESULTS:
A total of 59 patients (23 girls and 36 boys) underwent PEPSiT during the study period. Ten/59 patients (16.9%) had recurrent PSD after open repair, and 4/59 (6.7%) presented a concomitant pilonidal cyst. All children underwent laser epilation pre- and postoperatively over the last 15 months. The average length of surgery was 27.5 min (range 20-45). The average pain score during the first 48 postoperative hours was 2.7 (range 2-5), and the average analgesic requirement was 20 h (range 16-24). The average hospitalization was 22.4 h (range 18-36). At 1 month postoperatively, external openings were healed in all patients. During follow-up, 1 recurrence (1.6%) was recorded and successfully re-treated with PEPSiT.
CONCLUSIONS:
We believe that PEPSiT represents the technique of choice for treatment of PSD in the pediatric population. It is crucial to standardize the technique consisting of pre- and postoperative laser epilation, PEPSiT, and accurate postoperative wound management with eosin and sulfadiazine spray
The Evolution of Environmental Quenching Timescales to
Using a sample of 4 galaxy clusters at and 10 galaxy
clusters at , we measure the environmental quenching
timescale, , corresponding to the time required after a galaxy is accreted
by a cluster for it to fully cease star formation. Cluster members are selected
by a photometric-redshift criterion, and categorized as star-forming,
quiescent, or intermediate according to their dust-corrected rest-frame colors
and magnitudes. We employ a "delayed-then-rapid" quenching model that relates a
simulated cluster mass accretion rate to the observed numbers of each type of
galaxy in the cluster to constrain . For galaxies of mass , we find a quenching timescale of 1.24 Gyr
in the cluster sample, and 1.50 Gyr at . Using values
drawn from the literature, we compare the redshift evolution of to
timescales predicted for different physical quenching mechanisms. We find
to depend on host halo mass such that quenching occurs over faster timescales
in clusters relative to groups, suggesting that properties of the host halo are
responsible for quenching high-mass galaxies. Between and , we
find that evolves faster than the molecular gas depletion timescale and
slower than an SFR-outflow timescale, but is consistent with the evolution of
the dynamical time. This suggests that environmental quenching in these
galaxies is driven by the motion of satellites relative to the cluster
environment, although due to uncertainties in the atomic gas budget at high
redshift, we cannot rule out quenching due to simple gas depletion
The importance of major mergers in the build up of stellar mass in brightest cluster galaxies at z=1
Recent independent results from numerical simulations and observations have
shown that brightest cluster galaxies (BCGs) have increased their stellar mass
by a factor of almost two between z~0.9 and z~0.2. The numerical simulations
further suggest that more than half this mass is accreted through major
mergers. Using a sample of 18 distant galaxy clusters with over 600
spectroscopically confirmed cluster members between them, we search for
observational evidence that major mergers do play a significant role. We find a
major merger rate of 0.38 +/- 0.14 mergers per Gyr at z~1. While the
uncertainties, which stem from the small size of our sample, are relatively
large, our rate is consistent with the results that are derived from numerical
simulations. If we assume that this rate continues to the present day and that
half of the mass of the companion is accreted onto the BCG during these
mergers, then we find that this rate can explain the growth in the stellar mass
of the BCGs that is observed and predicted by simulations. Major mergers
therefore appear to be playing an important role, perhaps even the dominant
one, in the build up of stellar mass in these extraordinary galaxies.Comment: 15 pages, 6 figures, accepted for publication in MNRAS. Reduced data
will be made available through the ESO archiv
The WAGGS project -- III. Discrepant mass-to-light ratios of Galactic globular clusters at high metallicity
Observed mass-to-light ratios (M/L) of metal-rich globular clusters (GCs) disagree with theoretical predictions. This discrepancy is of fundamental importance since stellar population models provide the stellar masses that underpin most of extragalactic astronomy, near and far. We have derived radial velocities for 1,622 stars located in the centres of 59 Milky Way GCs - twelve of which have no previous kinematic information - using integral-field unit data from the WAGGS project. Using N-body models, we then determine dynamical masses and M/L ratios for the studied clusters. Our sample includes NGC 6528 and NGC 6553, which extend the metallicity range of GCs with measured M/L up to [Fe/H] ~ -0.1 dex. We find that metal-rich clusters have M/L more than two times lower than what is predicted by simple stellar population models. This confirms that the discrepant M/L-[Fe/H] relation remains a serious concern. We explore how our findings relate to previous observations, and the potential causes for the divergence, which we conclude is most likely due to dynamical effects
JAK/Stat5-mediated subtype-specific lymphocyte antigen 6 complex, locus G6D (LY6G6D) expression drives mismatch repair proficient colorectal cancer
Background: Human microsatellite-stable (MSS) colorectal cancers (CRCs) are immunologically "cold" tumour subtypes characterized by reduced immune cytotoxicity. The molecular linkages between immune-resistance and human MSS CRC is not clear. Methods: We used transcriptome profiling, in silico analysis, immunohistochemistry, western blot, RT-qPCR and immunofluorescence staining to characterize novel CRC immune biomarkers. The effects of selective antagonists were tested by in vitro assays of long term viability and analysis of kinase active forms using anti-phospho antibodies. Results: We identified the lymphocyte antigen 6 complex, locus G6D (LY6G6D) as significantly overexpressed (around 15-fold) in CRC when compared with its relatively low expression in other human solid tumours. LY6G6D up-regulation was predominant in MSS CRCs characterized by an enrichment of immune suppressive regulatory T-cells and a limited repertoire of PD-1/PD-L1 immune checkpoint receptors. Coexpression of LY6G6D and CD15 increases the risk of metastatic relapse in response to therapy. Both JAK-STAT5 and RAS-MEK-ERK cascades act in concert as key regulators of LY6G6D and Fucosyltransferase 4 (FUT4), which direct CD15-mediated immune-resistance. Momelotinib, an inhibitor of JAK1/JAK2, consistently abrogated the STAT5/LY6G6D axis in vitro, sensitizing MSS cancer cells with an intact JAK-STAT signaling, to efficiently respond to trametinib, a MEK inhibitor used in clinical setting. Notably, colon cancer cells can evade JAK2/JAK1-targeted therapy by a reversible shift of the RAS-MEK-ERK pathway activity, which explains the treatment failure of JAK1/2 inhibitors in refractory CRC. Conclusions: Combined targeting of STAT5 and MAPK pathways has superior therapeutic effects on immune resistance. In addition, the new identified LY6G6D antigen is a promising molecular target for human MSS CRC
Loss of Primary Cilia Potentiates BRAF/MAPK Pathway Activation in Rhabdoid Colorectal Carcinoma: A Series of 21 Cases Showing Ciliary Rootlet CoiledCoil (CROCC) Alterations
A rhabdoid colorectal tumor (RCT) is a rare cancer with aggressive clinical behavior. Recently, it has been recognized as a distinct disease entity, characterized by genetic alterations in the SMARCB1 and Ciliary Rootlet Coiled-Coil (CROCC). We here investigate the genetic and immunophenotypic profiling of 21 RCTs using immunohistochemistry and next-generation sequencing. Mismatch repair-deficient phenotypes were identified in 60% of RCTs. Similarly, a large proportion of cancers exhibited the combined marker phenotype (CK7-/CK20-/CDX2-) not common to classical adenocarcinoma variants. More than 70% of cases displayed aberrant activation of the mitogen-activated protein kinase (MAPK) pathway with mutations prevalently in BRAF V600E. SMARCB1/INI1 expression was normal in a large majority of lesions. In contrast, ciliogenic markers including CROCC and γ-tubulin were globally altered in tumors. Notably, CROCC and γ-tubulin were observed to colocalize in large cilia found on cancer tissues but not in normal controls. Taken together, our findings indicate that primary ciliogenesis and MAPK pathway activation contribute to the aggressiveness of RCTs and, therefore, may constitute a novel therapeutic target
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