1,177 research outputs found
The Arches cluster out to its tidal radius: dynamical mass segregation and the effect of the extinction law on the stellar mass function
The Galactic center is the most active site of star formation in the Milky
Way Galaxy, where particularly high-mass stars have formed very recently and
are still forming today. However, since we are looking at the Galactic center
through the Galactic disk, knowledge of extinction is crucial when studying
this region. The Arches cluster is a young, massive starburst cluster near the
Galactic center. We observed the Arches cluster out to its tidal radius using
Ks-band imaging obtained with NAOS/CONICA at the VLT combined with Subaro/Cisco
J-band data to gain a full understanding of the cluster mass distribution. We
show that the determination of the mass of the most massive star in the Arches
cluster, which had been used in previous studies to establish an upper mass
limit for the star formation process in the Milky Way, strongly depends on the
assumed slope of the extinction law. Assuming the two regimes of widely used
infrared extinction laws, we show that the difference can reach up to 30% for
individually derived stellar masses and Delta AKs ~ 1 magnitude in acquired
Ks-band extinction, while the present-day mass function slope changes by ~ 0.17
dex. The present-day mass function slope derived assuming the more recent
extinction law increases from a flat slope of alpha_{Nishi}=-1.50 \pm0.35 in
the core (r<0.2 pc) to alpha_{Nishi}=-2.21 \pm0.27 in the intermediate annulus
(0.2 <r<0.4 pc), where the Salpeter slope is -2.3. The mass function steepens
to alpha_{Nishi}=-3.21 \pm0.30 in the outer annulus (0.4<r<1.5 pc), indicating
that the outer cluster region is depleted of high-mass stars. This picture is
consistent with mass segregation owing to the dynamical evolution of the
cluster.Comment: accepted to be published in A&
The orbital motion of the Quintuplet cluster - a common origin for the Arches and Quintuplet clusters?
We investigate the orbital motion of the Quintuplet cluster near the Galactic
center with the aim of constraining formation scenarios of young, massive star
clusters in nuclear environments. Three epochs of adaptive optics high-angular
resolution imaging with Keck/NIRC2 and VLT/NACO were obtained over a time
baseline of 5.8 years, delivering an astrometric accuracy of 0.5-1 mas/yr.
Proper motions were derived in the cluster reference frame and were used to
distinguish cluster members from the majority of field stars. Fitting the
cluster and field proper motion distributions with 2D gaussian models, we
derive the orbital motion of the cluster for the first time. The Quintuplet is
moving with a 2D velocity of 132 +/- 15 km/s with respect to the field along
the Galactic plane, which yields a 3D orbital velocity of 167 +/- 15 km/s when
combined with the previously known radial velocity. From a sample of 119 stars
measured in three epochs, we derive an upper limit to the velocity dispersion
in the core of the Quintuplet cluster of sigma_1D < 10 km/s. Knowledge of the
three velocity components of the Quintuplet allows us to model the cluster
orbit in the potential of the inner Galaxy. Comparing the Quintuplet's orbit
with the Arches orbit, we discuss the possibility that both clusters originated
in the same area of the central molecular zone. [abridged]Comment: 40 pages, 12 figures, accepted for publication in Ap
Circumstellar discs in Galactic centre clusters: Disc-bearing B-type stars in the Quintuplet and Arches clusters
We investigate the circumstellar disc fraction as determined from L-band
excess observations of the young, massive Arches and Quintuplet clusters
residing in the central molecular zone of the Milky Way. The Quintuplet cluster
was searched for L-band excess sources for the first time. We find a total of
26 excess sources in the Quintuplet cluster and 21 in the Arches cluster, of
which 13 are new detections. With the aid of proper motion membership samples,
the disc fraction of the Quintuplet cluster was derived for the first time to
be 4.0 +/- 0.7%. There is no evidence for a radially varying disc fraction in
this cluster. In the case of the Arches cluster, a disc fraction of 9.2 +/-
1.2% approximately out to the cluster's predicted tidal radius, r < 1.5 pc, is
observed. This excess fraction is consistent with our previously found disc
fraction in the cluster in the radial range 0.3 < r < 0.8 pc. In both clusters,
the host star mass range covers late A- to early B-type stars, 2 < M < 15 Msun,
as derived from J-band photospheric magnitudes. We discuss the unexpected
finding of dusty circumstellar discs in these UV intense environments in the
context of primordial disc survival and formation scenarios of secondary discs.
We consider the possibility that the L-band excess sources in the Arches and
Quintuplet clusters could be the high-mass counterparts to T Tauri
pre-transitional discs. As such a scenario requires a long pre-transitional
disc lifetime in a UV intense environment, we suggest that mass transfer discs
in binary systems are a likely formation mechanism for the B-star discs
observed in these starburst clusters.Comment: 47 pages, 22 figures, accepted by A&
Proper motions of the Arches cluster with Keck-LGS Adaptive Optics: the first kinematic mass measurement of the Arches
We report the first detection of the intrinsic velocity dispersion of the
Arches cluster - a young (~2 Myr), massive (~10,000 Solar Mass) starburst
cluster located near the Galactic center. This was accomplished using proper
motion measurements within the central region of the cluster, obtained with the
laser guide star adaptive optics system at Keck Observatory over a 3 year time
baseline (2006-2009). This uniform dataset results in proper motion
measurements that are improved by a factor ~5 over previous measurements from
heterogeneous instruments, yielding internal velocity dispersion estimates 0.15
+/- 0.01 mas/yr, which corresponds to 5.4 +/- 0.4 km/s at a distance of 8.4
kpc.
Projecting a simple model for the cluster onto the sky to compare with our
proper motion dataset, in conjunction with surface density data, we estimate
the total present-day mass of the cluster to be 15,000 (+7400 -6000) Solar
masses. The mass in stars observed within a cylinder of radius R=0.4 pc is
found to be 9000 (+4000 -3500) Solar Masses at formal 3-sigma confidence. This
mass measurement is free from assumptions about the mass function of the
cluster, and thus may be used to check mass estimates from photometry and
simulation. When we conduct this check, we find that the present-day mass
function of the Arches cluster is likely either top-heavy or truncated at
low-mass, or both.
Collateral benefits of our data and analysis include: 1. cluster membership
probabilities, which may be used to extract a clean cluster sample for future
photometric work; 2. a refined estimate of the bulk motion of the Arches
cluster with respect to the field, which we find to be 172 +/- 15 km/s, which
is slightly slower than suggested by previous VLT-Keck measurements; and 3. a
velocity dispersion estimate for the field itself, which is likely dominated by
the inner galactic bulge and the nuclear disk.Comment: 73 pages, 28 figures, 12 tables, ApJ accepte
The Bolocam Galactic Plane Survey IV: 1.1 and 0.35 mm Dust Continuum Emission in the Galactic Center Region
The Bolocam Galactic Plane Survey (BGPS) data for a six square degree region
of the Galactic plane containing the Galactic center is analyzed and compared
to infrared and radio continuum data. The BGPS 1.1 mm emission consists of
clumps interconnected by a network of fainter filaments surrounding cavities, a
few of which are filled with diffuse near-IR emission indicating the presence
of warm dust or with radio continuum characteristic of HII regions or supernova
remnants. New 350 {\mu}m images of the environments of the two brightest
regions, Sgr A and B, are presented. Sgr B2 is the brightest mm-emitting clump
in the Central Molecular Zone and may be forming the closest analog to a super
star cluster in the Galaxy. The Central Molecular Zone (CMZ) contains the
highest concentration of mm and sub-mm emitting dense clumps in the Galaxy.
Most 1.1 mm features at positive longitudes are seen in silhouette against the
3.6 to 24 {\mu}m background observed by the Spitzer Space Telescope. However,
only a few clumps at negative longitudes are seen in absorption, confirming the
hypothesis that positive longitude clumps in the CMZ tend to be on the
near-side of the Galactic center, consistent with the suspected orientation of
the central bar in our Galaxy. Some 1.1 mm cloud surfaces are seen in emission
at 8 {\mu}m, presumably due to polycyclic aromatic hydrocarbons (PAHs). A
~0.2\degree (~30 pc) diameter cavity and infrared bubble between l \approx
0.0\degree and 0.2\degree surrounds the Arches and Quintuplet clusters and Sgr
A. The bubble contains several clumpy dust filaments that point toward Sgr
A\ast; its potential role in their formation is explored. [abstract truncated]Comment: 76 pages, 22 figures, published in ApJ:
http://iopscience.iop.org/0004-637X/721/1/137
Treatment expectations and perception of therapy in adult patients with spinal muscular atrophy receiving nusinersen
Background and purpose: This was an investigation of treatment expectations and of the perception of therapy in adult patients with 5q-associated spinal muscular atrophy (5q-SMA) receiving nusinersen.
Methods: A prospective, non-interventional observational study of nusinersen treatment in adult 5q-SMA patients was conducted at nine SMA centers in Germany. The functional status, treatment expectations and perceived outcomes were assessed using the Amyotrophic Lateral Sclerosis Functional Rating Scale-extended (ALS-FRS-ex), the Measure Yourself Medical Outcome Profile (MYMOP2), the Treatment Satisfaction Questionnaire for Medication (TSQM-9) and the Net Promoter Score (NPS).
Results: In all, 151 patients were included with a median age of 36 years (15-69 years). SMA type 3 (n = 90, 59.6%) prevailed, followed by type 2 (33.8%) and type 1 (6.6%). In SMA types 1-3, median ALS-FRS-ex scores were 25, 33 and 46 (of 60 scale points), respectively. MYMOP2 identified distinct treatment expectations: head verticalization (n = 13), bulbar function (n = 16), arm function (n = 65), respiration (n = 15), trunk function (n = 34), leg function (n = 76) and generalized symptoms (n = 77). Median symptom severity decreased during nusinersen treatment (median observational period 6.1 months, 0.5-16 months) from 3.7 to 3.3 MYMOP2 score points (p < 0.001). The convenience of drug administration was critical (49.7 of 100 TSQM-9 points, SD 22); however, the overall treatment satisfaction was high (74.3, SD 18) and the recommendation rating very positive (NPS +66).
Conclusions: Nusinersen was administered across a broad range of ages, disease durations and motor function deficits. Treatment expectations were highly differentiated and related to SMA type and functional status. Patient-reported outcomes demonstrated a positive perception of nusinersen therapy in adult patients with 5q-SMA
Needle Knife-assisted Endoscopic Polypectomy for a Large Inflammatory Fibroid Colon Polyp by Making Its Stalk into an Omega Shape Using an Endoloop
Colonic inflammatory fibroid polyp (IFP) is an uncommon benign polypoid lesion, which is composed of fibroblasts, numerous small vessels and edematous connective tissue with marked eosinophilic inflammatory cell infiltration. This condition is frequently detected in the stomach and small intestine, but uncommon in the colon. Although IFP is a benign lesion, surgical resections are performed in most colonic cases because the polyps are usually too large to resect endoscopically. Only three patients underwent endoscopic polypectomy in our literature reviews. Here, we present a case of IFP in the descending colon successful endoscopically resected using a novel technique of trapping its stalk with an endoloop, forming the stalk into an omega shape, and then dissecting the stalk with a needle knife
Informal Caregiving in Amyotrophic Lateral Sclerosis (ALS): A High Caregiver Burden and Drastic Consequences on Caregivers’ Lives
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that causes progressive autonomy loss and need for care. This does not only affect patients themselves, but also the patients’ informal caregivers (CGs) in their health, personal and professional lives. The big efforts of this multi-center study were not only to evaluate the caregivers’ burden and to identify its predictors, but it also should provide a specific understanding of the needs of ALS patients’ CGs and fill the gap of knowledge on their personal and work lives. Using standardized questionnaires, primary data from patients and their main informal CGs (n = 249) were collected. Patients’ functional status and disease severity were evaluated using the Barthel Index, the revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) and the King’s Stages for ALS. The caregivers’ burden was recorded by the Zarit Burden Interview (ZBI). Comorbid anxiety and depression of caregivers were assessed by the Hospital Anxiety and Depression Scale. Additionally, the EuroQol Five Dimension Five Level Scale evaluated their health-related quality of life. The caregivers’ burden was high (mean ZBI = 26/88, 0 = no burden, ≥24 = highly burdened) and correlated with patients’ functional status (rp = −0.555, p < 0.001, n = 242). It was influenced by the CGs’ own mental health issues due to caregiving (+11.36, 95% CI [6.84; 15.87], p < 0.001), patients’ wheelchair dependency (+9.30, 95% CI [5.94; 12.66], p < 0.001) and was interrelated with the CGs’ depression (rp = 0.627, p < 0.001, n = 234), anxiety (rp = 0.550, p < 0.001, n = 234), and poorer physical condition (rp = −0.362, p < 0.001, n = 237). Moreover, female CGs showed symptoms of anxiety more often, which also correlated with the patients’ impairment in daily routine (rs = −0.280, p < 0.001, n = 169). As increasing disease severity, along with decreasing autonomy, was the main predictor of caregiver burden and showed to create relevant (negative) implications on CGs’ lives, patient care and supportive therapies should address this issue. Moreover, in order to preserve the mental and physical health of the CGs, new concepts of care have to focus on both, on not only patients but also their CGs and gender-associated specific issues. As caregiving in ALS also significantly influences the socioeconomic status by restrictions in CGs’ work lives and income, and the main reported needs being lack of psychological support and a high bureaucracy, the situation of CGs needs more attention. Apart from their own multi-disciplinary medical and psychological care, more support in care and patient management issues is required
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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