ABSTRACT
Feedback from an active galactic nucleus (AGN) is often implicated as a mechanism that leads to the quenching of galactic star formation. However, AGN-driven quenching is challenging to ...reconcile with observations that AGN hosts tend to harbour equal (or even excess) amounts of gas compared with inactive galaxies of similar stellar mass. In this paper, we investigate whether AGN feedback happens on sub-galactic (kpc) scales, an effect that might be difficult to detect with global gas measurements. Using kpc-scale measurements of molecular gas ($\Sigma _{\rm H_2}$) and stellar mass (Σ⋆) surface densities, taken from the Extragalactic Data base for Galaxy Evolution–Calar Alto Legacy Integral Field Area survey, we show that the gas fractions of central AGN regions are typically a factor of ∼ 2 lower than those in star-forming regions. Based on four galaxies with the best spaxel statistics, the difference between AGN and star-forming gas fractions is seen even within a given galaxy, indicating that AGN feedback is able to deplete the molecular gas reservoir in the central few kpc.
Abstract To investigate the effects of stellar feedback on the gravitational state of giant molecular clouds (GMCs), we study 12 CO and 13 CO Atacama Large Millimeter/submillimeter Array maps of nine ...GMCs distributed throughout the Large Magellanic Cloud (LMC), the nearest star-forming galaxy to our own. We perform noise and resolution matching on the sample, working at a common resolution of 3.″5 (0.85 pc at the LMC distance of 50 kpc), and we use the Spectral Clustering for Molecular Emission Segmentation clustering algorithm to identify discrete substructure, or “clumps.” We supplement these data with three tracers of recent star formation: 8 μ m surface brightness, continuum-subtracted H α flux, and interstellar radiation field energy density inferred from dust emission. The 12 CO clumps identified cover a range of 3.6 dex in luminosity-based mass and 2.4 dex in average 8 μ m surface brightness, representative of the wide range of conditions of the interstellar medium in the LMC. Our observations suggest evidence for increased turbulence in these clouds. While the turbulent linewidths are correlated with clump surface density, in agreement with previous observations, we find even better correlation with the three star formation activity tracers considered, suggesting stellar energy injection plays a significant role in the dynamical state of the clumps. The excess linewidths we measure do not appear to result from opacity broadening. 12 CO clumps are found to be typically less gravitationally bound than 13 CO clumps, with some evidence of the kinetic-to-gravitational potential energy ratio increasing with star formation tracers. Further multiline analysis may better constrain the assumptions made in these calculations.
Shocks and torques produced by non-axisymmetric structures such as spiral arms and bars may transport gas to galaxy central regions. We test this hypothesis by studying the dependence of the ...concentration of CO luminosity (
C
CO
) and molecular gas (
C
mol
) and the star formation rate (
C
SFR
) in the central ∼2 kpc on the strength of non-axisymmetric disk structure using a sample of 57 disk galaxies selected from the EDGE-CALIFA survey. The
C
mol
is calculated using a CO-to-H
2
conversion factor that decreases with higher metallicity and higher stellar surface density. We find that
C
mol
is systematically 0.22 dex lower than
C
CO
. We confirm that high
C
mol
and strong non-axisymmetric disk structure are more common in barred galaxies than in unbarred galaxies. However, we find that spiral arms also increase
C
mol
. We show that there is a good correlation between
C
mol
and the strength of non-axisymmetric structure (which can be due to a bar, spiral arms, or both). This suggests that the stronger the bars and spirals, the more efficient the galaxy is at transporting cold gas to its center. Despite the small subsample size, the
C
mol
of the four Seyferts are not significantly reduced compared to inactive galaxies of similar disk structure, implying that the active galactic nucleus feedback in Seyferts may not notably affect the molecular gas distribution in the central ∼2 kpc. We find that
C
SFR
tightly correlates with
C
mol
in both unbarred and barred galaxies. Likewise, elevated
C
SFR
is found in galaxies with strong disk structure. Our results suggest that the disk structure, either spirals or bars, can transport gas to the central regions, with higher inflow rates corresponding to stronger structure, and consequently boost central star formation. Both spirals and bars play, therefore, an essential role in the secular evolution of disk galaxies.
Acute rejection is seen in 85 percent of composite vascular allogeneic transplants despite long-term immunosuppression. Recently, it was reported that the induction of endotoxin tolerance prolonged ...heart allograft survival in mice. However, it produced side effects in all the animals secondary to the inflammatory reaction. Galactomannan has shown endotoxin tolerance without this side effect in vitro. The authors hypothesized that galactomannan-induced endotoxin tolerance delays acute rejection in vascular allogeneic transplantation without the side effects produced by lipopolysaccharide.
Twenty-four rat hindlimb transplants were divided into four groups according to the preconditioning received: control, lipopolysaccharide (0.16 ml/kg), galactomannan 72 hours before (galactomannan-72) (8 ml/kg), and galactomannan 24 hours before (galactomannan-24) (8 ml/kg). Median acute rejection time, weight loss, and diarrheal episodes were monitored. Blood samples were collected at 0, 7, 21, 30, 45, and 60 days. Plasma cytokines (i.e., tumor necrosis factor alpha, interferon gamma), peripheral chimerism, and lymphocyte percentages were analyzed.
Median allograft survival was 40 days (range, 40 to 44 days) in the control group, 68 days (range, 61 to 71 days) in the lipopolysaccharide group, and 70 days (range, 69 to 73 days) in both galactomannan groups (p = 0.001). Weight loss was higher in the lipopolysaccharide group (p < 0.001), as was the 83.3 percent rate of diarrheal episodes (control, 0 percent, p = 0.015; galactomannan-72, 0 percent, p = 0.015; and galactomannan-24, 16.7 percent, p = 0.02). Preconditioned rats had higher peripheral blood chimerism (lipopolysaccharide, 2.30 ± 0.13 percent; galactomannan-72, 2.63 ±1.46 percent; and galactomannan-24, 2.47 ± 0.19 percent) compared to the control group (2.06 ± 0.36 percent) (lipopolysaccharide, p = 0.04; galactomannan-72, p = 0.002; and galactomannan-24, p = 0.002).
Induction of endotoxin tolerance delays acute rejection in the rat hindlimb transplantation model. Galactomannan preconditioning has no lipopolysaccharide side effects and was equally effective in delaying acute rejection.
The contributions of this experimental work are very incipient. Although the use of galactomannan in clinical practice requires more studies to assess its safety, there is no doubt that immunomodulation may be one of the responses that solve the problem of long-term immunosuppression.
Feedback from star formation is a critical component of the evolution of galaxies and their interstellar medium. At parsec scales internal to molecular clouds, however, the observed signatures of ...that feedback on the physical properties of CO-emitting gas have often been weak or inconclusive. We present subparsec observations of H2CO in the 30 Doradus region, which contains the massive star cluster R136 that is clearly exerting feedback on its neighboring gas. H2CO provides a direct measure of gas kinetic temperature, and we find a trend of decreasing temperature with projected distance from R136 that may be indicative of gas heating by the stars. While it has been suggested that mechanical heating affects H2CO-measured temperature, we do not observe any correlation between TK and line width. The lack of an enhancement in mechanical feedback close to R136 is consistent with the absence of a radial trend in gravitational boundedness seen the Atacama Large Millimeter/submillimeter Array CO observations. Estimates of cosmic-ray flux in the region are quite uncertain, but can plausibly explain the observed temperatures if R136 itself is the dominant local source of energetic protons. The observations presented here are also consistent with the H2CO-emitting gas near R136 being dominated by direct radiation from R136 and photoelectric heating in the photodissociation regions.
Chronic musculoskeletal (MSK) pain is one of the most common medical complaints worldwide and musculoskeletal injuries have an enormous social and economical impact. Current pharmacological and ...surgical treatments aim to relief pain and restore function; however, unsatiscactory outcomes are commonly reported. In order to find an accurate treatment to such pathologies, over the last years, there has been a significantly increasing interest in cellular therapies, such as adipose-derived mesenchymal stem cells (AMSCs). These cells represent a relatively new strategy in regenerative medicine, with many potential applications, especially regarding MSK disorders, and preclinical and clinical studies have demonstrated their efficacy in muscle, tendon, bone and cartilage regeneration. Nevertheless, several worries about their safety and side effects at long-term remain unsolved. This article aims to review the current state of AMSCs therapy in the treatment of several MSK diseases and their clinical applications in veterinary and human medicine.
The spatial variations of the gas-to-dust ratio (GDR) provide constraints on the chemical evolution and life-cycle of dust in galaxies. We examine the relation between dust and gas at 10-50 pc ...resolution in the Large and Small Magellanic Clouds (LMC and SMC) based on Herschel far-infrared (FIR), H I 21 cm, CO, and H alpha observations. We investigate the range of CO-to-Hsub 2 conversion factor to best account for all the molecular gas in the beam of the observations, and find upper limits on XCO to be 6 x 10sup 20 cmsup -2 Ksup -1 kmsup -1 s in the LMC (Z = 0.5Z) at 15 pc resolution, and 4 x 1021 cmsup -2 Ksup -1 kmsup -1 s in the SMC (Z = 0.2Z) at 45 pc resolution. Our analysis demonstrates that obtaining robust ISM masses remains a non-trivial endeavor even in the local Universe using state-of-the-art maps of thermal dust emission.
We present new sensitive CO(2-1) observations of the 30 Doradus region in the Large Magellanic Cloud. We identify a chain of three newly discovered molecular clouds that we name KN1, KN2, and KN3 ...lying within 2-14 pc in projection from the young massive cluster R136 in 30 Doradus. Excited H2 2.12 m emission is spatially coincident with the molecular clouds, but ionized Brγ emission is not. We interpret these observations as the tails of pillar-like structures whose ionized heads are pointing toward R136. Based on infrared photometry, we identify a new generation of stars forming within this structure.
Developmental dysplasia of the hip (DDH) is the most common disorder found in newborns. The consequences of DDH can be mitigated with early diagnosis and nonoperative treatment, but existing ...approaches do not address the current training deficit in making an early diagnosis.
Can ultrasound be taught to and used reliably by different providers to identify DDH in neonates?
This was a prospective observational study of a series of neonates referred for an evaluation of their hips. An experienced clinician trained three second examiners (a pediatric orthopaedic surgeon, an orthopaedic resident, and a pediatrician) in performing an ultrasound-enhanced physical examination. The 2-hour training process included video and clinical didactic sessions aimed to teach examiners to differentiate between stable and unstable hips in newborns using ultrasound. The experienced clinician was a pediatric orthopaedic surgeon who uses ultrasound regularly in clinical practice. Materials required for training include one ultrasound device. A total of 227 infants (454 hips) were examined by one of the three second examiners and the experienced clinician (gold standard) to assess reliability. Of the 454 hips reviewed, there were 18 dislocations, 24 unstable hips, and 63 dysplastic hips, and the remainder had normal findings. The cohort was composed of a series of patients younger than 6 months referred to a specialty pediatric orthopaedic practice.
Ultrasound-enhanced physical examination of the hip was easily taught, and the results were reliable among different levels of providers. The intraclass correlation coefficient between the gold-standard examiner and the other examiners for all hips was 0.915 (p = 0.001). When adjusting for only the binary outcome of normal versus abnormal hips, the intraclass correlation coefficient was 0.97 (p = 0.001). Thus, the agreement between learners and the experienced examiner was very high after learners completed the course.
After a 2-hour course, physicians were able to understand and reliably examine neonatal children using ultrasound to assess for DDH. The success of the didactic approach outlined in this study supports the need for ultrasound-enhanced examination training for the diagnosis of DDH in orthopaedic surgery and pediatric residency core curriculums. Training programs would best be supported through established residency programs. Expansion of training more residents in the use of ultrasound-enhanced physical examinations would require a study to determine its efficacy. This finding highlights the need for further research in implementing ultrasound-enhanced physical examinations on a broader scale.
Level II, diagnostic study.
The extended ultraviolet (XUV) disk galaxies are some of the most interesting objects studied in the last few years. The UV emission, revealed by GALEX, extends well beyond the optical disk after the ...drop in Hα emission, the usual tracer of star formation. This shows that sporadic star formation can occur in a large fraction of the HI disk at radii up to 3 or 4 times the optical radius. In most galaxies, these regions are poor in stars and are dominated by under-recycled gas; they therefore bear some similarity to the early stages of spiral galaxies and high-redshift galaxies. One remarkable example is M83, a nearby galaxy with an extended UV disk reaching 2 times the optical radius. It offers the opportunity to search for molecular gas and to characterize the star formation in outer disk regions, traced by the UV emission. We obtained CO(2-1) observations with ALMA of a small region in a 1.5′ × 3′ rectangle located at rgal = 7.85′ over a bright UV region of M83. There is no CO detection, in spite of the abundance of HI gas, and the presence of young stars traced by their HII regions. Our spatial resolution (17 pc × 13 pc) was perfectly fitted to detect giant molecular clouds (GMC), but none were detected. The corresponding upper limits occur in a region of the Kennicutt–Schmidt diagram where dense molecular clouds are expected. Stacking our data over HI-rich regions, using the observed HI velocity, we obtain a tentative detection corresponding to a H2-to-HI mass ratio of < 3 × 10−2. A possible explanation is that the expected molecular clouds are CO-dark because of the strong UV radiation field. This field preferentially dissociates CO with respect to H2, due to the small size of the star-forming clumps in the outer regions of galaxies.
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