1,828 research outputs found
Understanding the Unique Assembly History of Central Group Galaxies
Central Galaxies (CGs) in massive halos live in unique environments with
formation histories closely linked to that of the host halo. In local clusters
they have larger sizes () and lower velocity dispersions (sigma) at fixed
stellar mass M_star, and much larger R_e at a fixed than field and
satellite galaxies (non-CGs). Using spectroscopic observations of group
galaxies selected from the COSMOS survey, we compare the dynamical scaling
relations of early-type CGs and non-CGs at z~0.6, to distinguish possible
mechanisms that produce the required evolution. CGs are systematically offset
towards larger R_e at fixed compared to non-CGs with similar M_star.
The CG R_e-M_star relation also shows differences, primarily driven by a
sub-population (~15%) of galaxies with large , while the M_star-sigma
relations are indistinguishable. These results are accentuated when double
Sersic profiles, which better fit light in the outer regions of galaxies, are
adopted. They suggest that even group-scale CGs can develop extended components
by these redshifts that can increase total and M_star estimates by
factors of ~2. To probe the evolutionary link between our sample and cluster
CGs, we also analyze two cluster samples at z~0.6 and z~0. We find similar
results for the more massive halos at comparable z, but much more distinct CG
scaling relations at low-z. Thus, the rapid, late-time accretion of outer
components, perhaps via the stripping and accretion of satellites, would appear
to be a key feature that distinguishes the evolutionary history of CGs.Comment: 18 pages, 14 Figures, ApJ in pres
AMUSE-Virgo II. Down-sizing in black hole accretion
(Abridged) We complete the census of nuclear X-ray activity in 100 early type
Virgo galaxies observed by the Chandra X-ray Telescope as part of the
AMUSE-Virgo survey, down to a (3sigma) limiting luminosity of 3.7E+38 erg/s
over 0.5-7 keV. The stellar mass distribution of the targeted sample, which is
mostly composed of formally `inactive' galaxies, peaks below 1E+10 M_Sun, a
regime where the very existence of nuclear super-massive black holes (SMBHs) is
debated. Out of 100 objects, 32 show a nuclear X-ray source, including 6 hybrid
nuclei which also host a massive nuclear cluster as visible from archival HST
images. After carefully accounting for contamination from nuclear low-mass
X-ray binaries based on the shape and normalization of their X-ray luminosity
function, we conclude that between 24-34% of the galaxies in our sample host a
X-ray active SMBH (at the 95% C.L.). This sets a firm lower limit to the black
hole occupation fraction in nearby bulges within a cluster environment. At face
value, the active fraction -down to our luminosity limit- is found to increase
with host stellar mass. However, taking into account selection effects, we find
that the average Eddington-scaled X-ray luminosity scales with black hole mass
as M_BH^(-0.62^{+0.13}_{-0.12}), with an intrinsic scatter of
0.46^({+0.08}_{-0.06}) dex. This finding can be interpreted as observational
evidence for `down-sizing' of black hole accretion in local early types, that
is, low mass black holes shine relatively closer to their Eddington limit than
higher mass objects. As a consequence, the fraction of active galaxies, defined
as those above a fixed X-ray Eddington ratio, decreases with increasing black
hole mass.Comment: Accepted for publication in ApJ (no changes wrt v1
Characterization and Degradation Behavior of AgarâCarbomer Based Hydrogels for Drug Delivery Applications: Solute Effect
In this study hydrogels synthesized from agarose and carbomer 974P macromers were selected for their potential application in spinal cord injury (SCI) repair strategies following their ability to carry cells and drugs. Indeed, in drug delivery applications, one of the most important issues to be addressed concerns hydrogel ability to provide a finely controlled delivery of loaded drugs, together with a coherent degradation kinetic. Nevertheless, solute effects on drug delivery system are often neglected in the large body of literature, focusing only on the characterization of unloaded matrices. For this reason, in this work, hydrogels were loaded with a chromophoric salt able to mimic, in terms of steric hindrance, many steroids commonly used in SCI repair, and its effects were investigated both from a structural and a rheological point of view, considering the pH-sensitivity of the material. Additionally, degradation chemistry was assessed by means of infrared bond response (FT-IR) and mass loss
An environmental study of the ultraluminous X-ray source population in early-type galaxies
Ultraluminous X-ray sources (ULXs) are some of the brightest phenomena found outside of a galaxy's nucleus, and their explanation typically invokes accretion of material onto a black hole. Here, we perform the largest population study to date of ULXs in early-type galaxies, focusing on whether a galaxy's large-scale environment can affect its ULX content. Using the AMUSE survey, which includes homogeneous X-ray coverage of 100 elliptical galaxies in the Virgo cluster and a similar number of elliptical galaxies in the field (spanning stellar masses of 108-1012 M â), we identify 37.9 ± 10.1 ULXs in Virgo and 28.1 ± 8.7 ULXs in the field. Across both samples, we constrain the number of ULXs per unit stellar mass, i.e., the ULX specific frequency, to be 0.062 ± 0.013 ULXs per 10 10 M â (or about 1 ULX per 1.6 Ă 10 11 M â of galaxy stellar mass). We find that the number of ULXs, the specific frequency of ULXs, and the average ULX spectral properties are all similar in both cluster and field environments. Contrary to late-type galaxies, we do not see any trend between specific ULX frequency and host galaxy stellar mass, and we show that dwarf ellipticals host fewer ULXs than later-type dwarf galaxies at a statistically meaningful level. Our results are consistent with ULXs in early-type galaxies probing the luminous tail of the low-mass X-ray binary population, and are briefly discussed in context of the influence of gravitational interactions on the long-term evolution of a galaxy's (older) stellar population
Educational status affects prognosis of patients with heart failure with reduced ejection fraction: A post-hoc analysis from the WARCEF trial.
AimsThe influence of social determinants of health (SDOH) on the prognosis of Heart Failure and reduced Ejection Fraction (HFrEF) is increasingly reported. We aim to evaluate the contribution of educational status on outcomes in patients with HFrEF.MethodsWe used data from the WARCEF trial, which randomized HFrEF patients with sinus rhythm to receive Warfarin or Aspirin; educational status of patients enrolled was collected at baseline. We defined three levels of education: low, medium and high level, according to the highest qualification achieved or highest school grade attended. We analysed the impact of the educational status on the risk of the primary composite outcome of all-cause death, ischemic stroke (IS) and intracerebral haemorrhage (ICH); components of the primary outcome were also analysed as secondary outcomes.Results2295 patients were included in this analysis; of these, 992 (43.2%) had a low educational level, 947 (41.3%) had a medium education level and the remaining 356 (15.5%) showed a high educational level. Compared to patients with high educational level, those with low educational status showed a high risk of the primary composite outcome (adjusted hazard ratio [aHR]: 1.31, 95% confidence intervals [CI] 1.02-1.69); a non-statistically significant association was observed in those with medium educational level (aHR: 1.20, 95%CI: .93-1.55). Similar results were observed for all-cause death, while no statistically significant differences were observed for IS or ICH.ConclusionCompared to patients with high educational levels, those with low educational status had worse prognosis. SDOH should be considered in patients with HFrEF.Clinical trial registrationNCT00041938
AMUSE-Field I: Nuclear X-ray Properties of Local Field and Group Spheroids across the Stellar Mass Scale
We present the first results from AMUSE-Field, a Chandra survey designed to
characterize the occurrence and intensity of low-level accretion onto
supermassive black holes (SMBHs) at the center of local early-type field
galaxies. This is accomplished by means of a Large Program targeting a
distance-limited (<30 Mpc) sample of 103 early types spanning a wide range in
stellar masses. We acquired new ACIS-S observations for 61 objects down to a
limiting (0.3-10 keV) luminosity of 2.5x10^38 erg/s, and we include an
additional 42 objects with archival (typically deeper) coverage. A nuclear
X-ray source is detected in 52 out of the 103 galaxies. After accounting for
potential contamination from low-mass X-ray binaries, we estimate that the
fraction of accreting SMBHs within the sample is 45+/-7 percent, which sets a
firm lower limit on the occupation fraction within the field. The measured
nuclear X-ray luminosities are invariably highly sub-Eddington, with
-8<log(L_X/L_Edd)<-4. As also found in a companion survey targeting Virgo early
types, the active fraction increases with increasing host galaxy stellar mass,
reflective of "Eddington incompleteness" within the lower-mass objects. For the
Field sample, the average nuclear X-ray luminosity scales with the host stellar
mass as M_star^(0.71+/-0.10), with an intrinsic scatter of 0.73+/-0.09 dex. A
majority of the AMUSE-Field galaxies (78%) inhabits groups, enabling us to
investigate the influence of group richness upon nuclear activity. We see no
evidence for a positive correlation between nuclear X-ray luminosity,
normalized to host properties, and galaxy density. Rather, while the scatter is
substantial, it appears that the Eddington-scaled X-ray luminosity of group
members may be slightly lower than for isolated galaxies, and that this trend
continues to cluster early-types.Comment: Corrected typos and references. 19 pages emulateapj, 7 figures, 4
tables. Accepted to Ap
Sex-related differences in presentation, treatment, and outcomes of Asian patients with atrial fibrillation: a report from the prospective APHRS-AF Registry.
We aimed to investigate the sex-related differences in the clinical course of patients with Atrial Fibrillation (AF) enrolled in the Asia-Pacific-Heart-Rhythm-Society Registry. Logistic regression was utilized to investigate the relationship between sex and oral anticoagulant, rhythm control strategies and the 1-year chance to maintain sinus rhythm. Cox-regression was utilized to assess the 1-year risk of all-cause, and cardiovascular death, thromboembolic events, acute coronary syndrome, heart failure, and major bleeding. In the whole cohort (4121 patients, 69â±â12 years,34.3% female), females had different cardiovascular risk factors, clinical manifestations, and disease perceptions than men, with more advanced age (72â±â11 vs 67â±â12 years, pâ<â0.001) and dyslipidemia (36.7% vs 41.7%, pâ=â0.002). Coronary artery disease was more prevalent in males (21.1% vs 16.1%, pâ<â0.001) as well as the use of antiplatelet drugs. Females had a higher use of oral anticoagulant (84.9% vs 81.3%, pâ=â0.004) but this difference was non-significant after adjustment for confounders. On multivariable analyses, females were less often treated with rhythm control strategies (Odds Ratio [OR] 0.44,95% Confidence Interval [CI] 0.38-0.51) and were less likely to maintain sinus rhythm (OR 0.27, 95% CI 0.22-0.34) compared to males. Cox-regressions analysis showed no sex-related differences for the risk of death, cardiovascular, and bleeding. The clinical management of Asian AF patients should consider several sex-related differences
Sigh in patients with acute hypoxemic respiratory failure and acute respiratory distress syndrome: the PROTECTION pilot randomized clinical trial
Background: Sigh is a cyclic brief recruitment manoeuvre: previous physiological studies showed that its use could be an interesting addition to pressure support ventilation to improve lung elastance, decrease regional heterogeneity and increase release of surfactant.
Research question: Is the clinical application of sigh during pressure support ventilation (PSV) feasible?
Study design and methods: We conducted a multi-center non-inferiority randomized clinical trial on adult intubated patients with acute hypoxemic respiratory failure or acute respiratory distress syndrome undergoing PSV. Patients were randomized to the No Sigh group and treated by PSV alone, or to the Sigh group, treated by PSV plus sigh (increase of airway pressure to 30 cmH2Ofor 3 seconds once per minute) until day 28 or death or successful spontaneous breathing trial. The primary endpoint of the study was feasibility, assessed as non-inferiority (5% tolerance) in the proportion of patients failing assisted ventilation. Secondary outcomes included safety, physiological parameters in the first week from randomization, 28-day mortality and ventilator-free days.
Results: Two-hundred fifty-eight patients (31% women; median age 65 [54-75] years) were enrolled. In the Sigh group, 23% of patients failed to remain on assisted ventilation vs. 30% in the No Sigh group (absolute difference -7%, 95%CI -18% to 4%; p=0.015 for non-inferiority). Adverse events occurred in 12% vs. 13% in Sigh vs. No Sigh (p=0.852). Oxygenation was improved while tidal volume, respiratory rate and corrected minute ventilation were lower over the first 7 days from randomization in Sigh vs. No Sigh. There was no significant difference in terms of mortality (16% vs. 21%, p=0.342) and ventilator-free days (22 [7-26] vs. 22 [3-25] days, p=0.300) for Sigh vs. No Sigh.
Interpretation: Among hypoxemic intubated ICU patients, application of sigh was feasible and without increased risk
The commissioning of the CUORE experiment: the mini-tower run
CUORE is a ton-scale experiment approaching the data taking phase in Gran Sasso National Laboratory. Its primary goal is to search for the neutrinoless double-beta decay in 130Te using 988 crystals of tellurim dioxide. The crystals are operated as bolometers at about 10 mK taking advantage of one of the largest dilution cryostat ever built. Concluded in March 2016, the cryostat commissioning consisted in a sequence of cool down runs each one integrating new parts of the apparatus. The last run was performed with the fully configured cryostat and the thermal load at 4 K reached the impressive mass of about 14 tons. During that run the base temperature of 6.3 mK was reached and maintained for more than 70 days. An array of 8 crystals, called mini-tower, was used to check bolometers operation, readout electronics and DAQ. Results will be presented in terms of cooling power, electronic noise, energy resolution and preliminary background measurements
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