Context. The radial metallicity distribution in the Galactic thin disc represents a crucial constraint for modelling disc formation and evolution. Open star clusters allow us to derive both the ...radial metallicity distribution and its evolution over time. Aims. In this paper we perform the first investigation of the present-day radial metallicity distribution based on Fe/H determinations in late type members of pre-main-sequence clusters. Because of their youth, these clusters are therefore essential for tracing the current interstellar medium metallicity. Methods. We used the products of the Gaia-ESO Survey analysis of 12 young regions (age < 100 Myr), covering Galactocentric distances from 6.67 to 8.70 kpc. For the first time, we derived the metal content of star forming regions farther than 500 pc from the Sun. Median metallicities were determined through samples of reliable cluster members. For ten clusters the membership analysis is discussed in the present paper, while for other two clusters (i.e. Chamaeleon I and Gamma Velorum) we adopted the members identified in our previous works. Results. All the pre-main-sequence clusters considered in this paper have close-to-solar or slightly sub-solar metallicities. The radial metallicity distribution traced by these clusters is almost flat, with the innermost star forming regions having Fe/H values that are 0.10−0.15 dex lower than the majority of the older clusters located at similar Galactocentric radii. Conclusions. This homogeneous study of the present-day radial metallicity distribution in the Galactic thin disc favours models that predict a flattening of the radial gradient over time. On the other hand, the decrease of the average Fe/H at young ages is not easily explained by the models. Our results reveal a complex interplay of several processes (e.g. star formation activity, initial mass function, supernova yields, gas flows) that controlled the recent evolution of the Milky Way.
The Galactic open clusters, in particular the oldest members, serve as excellent probes of the structure and evolution of the Galactic disk. Individual clusters provide excellent tests of stellar and ...dynamical evolution. Cluster spatial and age distributions provide insight into the processes of cluster formation and destruction that have allowed substantial numbers of old open clusters to survive. Spectroscopic and photometric data for the old clusters yield kinematic, abundance, and age information that clarifies the relationship between the old open cluster population and other Galactic populations. New samples of old open clusters, which span a large range in distance and age, are used to define disk abundance gradients and the cluster age-metallicity relationship, and they point to a complex history of chemical enrichment and mixing in the disk.
Context.
The
Gaia
-ESO Survey (GES) is a public, high-resolution spectroscopic survey, conducted with the multi-object spectrograph Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very ...Large Telescope (European Southern Observatory, ESO, Cerro Paranal, Chile) from December 2011 to January 2018.
Gaia
-ESO has targeted all the main stellar components of the Milky Way, including thin and thick disc, bulge, and halo. In particular, a large sample of open clusters has been observed, from very young ones, just out of the embedded phase, to very old ones.
Aims.
The different kinds of clusters and stars targeted in them are useful to reach the main science goals of the open cluster part of GES, which are the study of the open cluster structure and dynamics, the use of open clusters to constrain and improve stellar evolution models, and the definition of Galactic disc properties (e.g., metallicity distribution).
Methods.
The
Gaia
-ESO Survey is organised in 19 working groups (WGs), each one being responsible for a task. We describe here the work of three of them, one in charge of the selection of the targets within each cluster or association (WG4), one responsible for defining the most probable candidate member stars (WG1), and another one in charge of the preparation of the observations (WG6). As the entire GES has been conducted before the second
Gaia
data release, we could not make use of the
Gaia
astrometry to define cluster member candidates. We made use of public and private photometry to select the stars to be observed with FLAMES, once brought on a common astrometric system (the one defined by 2MASS). Candidate target selection was based on ground-based proper motions, radial velocities, and X-ray properties when appropriate, for example, and it was mostly used to define the position of the clusters’ evolutionary sequences in the colour-magnitude diagrams. Targets for GIRAFFE were then selected near the sequences in an unbiased way. We used known information on membership, when available, only for the few stars to be observed with UVES.
Results.
We collected spectra for 62 confirmed clusters in the main observing campaign (and a few more clusters were taken from the ESO archive). Among them are very young clusters, where the main targets are pre-main sequence stars, clusters with very hot and massive stars currently on the main sequence, intermediate-age and old clusters where evolved stars are the main targets. Our strategy of making the selection of targets as inclusive and unbiased as possible and of observing a significant and representative fraction of all possible targets permitted us to collect the largest, most accurate, and most homogeneous spectroscopic data set on open star clusters ever achieved.
Context. The nature of the metallicity gradient inside the solar circle (RGC < 8 kpc) is poorly understood, but studies of Cepheids and a small sample of open clusters suggest that it steepens in the ...inner disk. Aims. We investigate the metallicity gradient of the inner disk using a sample of inner disk open clusters that is three times larger than has previously been studied in the literature to better characterize the gradient in this part of the disk. Methods. We used the Gaia-ESO Survey (GES) Fe/H values and stellar parameters for stars in 12 open clusters in the inner disk from GES-UVES data. Cluster mean Fe/H values were determined based on a membership analysis for each cluster. Where necessary, distances and ages to clusters were determined via comparison to theoretical isochrones. Results. The GES open clusters exhibit a radial metallicity gradient of −0.10 ± 0.02 dex kpc-1, consistent with the gradient measured by other literature studies of field red giant stars and open clusters in the range RGC ~ 6−12 kpc. We also measure a trend of increasing Fe/H with increasing cluster age, as has also been found in the literature. Conclusions. We find no evidence for a steepening of the inner disk metallicity gradient inside the solar circle as earlier studies indicated. The age-metallicity relation shown by the clusters is consistent with that predicted by chemical evolution models that include the effects of radial migration, but a more detailed comparison between cluster observations and models would be premature.
Background Colorectal surgery is associated with considerable morbidity and prolonged length of stay (LOS). Recognizing the need for improvement, we implemented an enhanced recovery (ER) protocol for ...all patients undergoing elective colorectal surgery at an academic institution. Study Design A multidisciplinary team implemented an ER protocol based on: preoperative counseling with active patient participation, carbohydrate loading, multimodal analgesia with avoidance of intravenous opioids, intraoperative goal-directed fluid resuscitation, immediate postoperative feeding, and ambulation. Discharge requirements remained identical throughout. A before and after study design was undertaken comparing patients before (August 2012 to February 2013) and after implementation of an ER protocol (August 2013 to February 2014). Risk stratification was performed using the NSQIP risk calculator to calculate the predicted LOS for each patient based on 23 variables. Results One hundred and nine consecutive patients underwent surgery within the ER protocol compared with 98 consecutive historical controls (conventional). The risk-adjusted predicted LOS was similar for each group at 5.1 and 5.2 days. Substantial reductions were seen in LOS, morphine equivalents, intravenous fluids, return of bowel function, and overall complications with the ER group. There was a $7,129/patient reduction in direct cost, corresponding to a cost savings of $777,061 in the ER group. Patient satisfaction as measured by Press Ganey improved considerably during the study period. Conclusions Implementation of an ER protocol led to improved patient satisfaction and substantial reduction in LOS, complication rates, and costs for patients undergoing both open and laparoscopic colorectal surgery. These data demonstrate that small investments in the perioperative environment can lead to large returns.
Context. NGC 4815 is a populous ~500 Myr open cluster at Rgc ~ 7 kpc observed in the first six months of the Gaia-ESO Survey. Located in the inner Galactic disk, NGC 4815 is an important potential ...tracer of the abundance gradient, where relatively few intermediate age open clusters are found. Aims. The Gaia-ESO Survey data can provide an improved characterization of the cluster properties, such as age, distance, reddening, and abundance profile. Methods. We use the survey derived radial velocities, stellar atmospheric parameters, metallicity, and elemental abundances for stars targeted as potential members of this cluster to carry out an analysis of cluster properties. The radial velocity distribution of stars in the cluster field is used to define the cluster systemic velocity and derive likely cluster membership for stars observed by the Gaia-ESO Survey. We investigate the distributions of Fe and Fe-peak elements, alpha-elements, and the light elements Na and Al and characterize the cluster’s internal chemical homogeneity comparing it to the properties of radial velocity non-member stars. Utilizing these cluster properties, the cluster color-magnitude diagram is analyzed and theoretical isochrones are fit to derive cluster reddening, distance, and age. Results. NGC 4815 is found to have a mean metallicity of Fe/H = +0.03 ± 0.05 dex (s.d.). Elemental abundances of cluster members show typically very small internal variation, with internal dispersions of ~0.05 dex. The alpha-elements Ca/Fe and Si/Fe show solar ratios, but Mg/Fe is moderately enhanced, while Ti/Fe appears slightly deficient. As with many open clusters, the light elements Na/Fe and Al/Fe are enhanced, Na/Fe significantly so, although the role of internal mixing and the assumption of local thermodynamical equilibrium in the analysis remain to be investigated. From isochrone fits to color-magnitude diagrams, we find a cluster age of 0.5 to 0.63 Gyr, a reddening of E(B − V) = 0.59 to 0.65, and a distance modulus (m − M)0 = 11.95 to 12.20, depending on the choice of theoretical models, leading to a Galactocentric distance of 6.9 kpc.
People with diabetes often have difficulty maintaining optimal blood-glucose levels, risking progressive complications that can lead to unscheduled care. Unscheduled care can include attending ...emergency departments, ambulance call outs, out-of-hours care and non-elective hospital admissions. A large proportion of non-elective hospital admissions involve people with diabetes, with significant health and economic burden.
To identify precipitating factors influencing diabetes-related unscheduled hospital admissions, exploring potential preventative strategies to reduce admissions.
Thirty-six people with type 1 (n=11) or type 2 (n=25) diabetes, admitted to hospital for unscheduled diabetes-related care across three hospitals in Scotland, Northern Ireland and the Republic of Ireland were interviewed. Participants were admitted for peripheral limb complications (n=17), hypoglycaemia (n=5), hyperglycaemia (n=6), or for comorbidities presenting with erratic blood glucose levels (n=8).
Factors precipitating admissions were examined using Framework analysis.
Three aspects of care influenced unscheduled admissions: inadequate knowledge; restricted provision; and complexities in engagement. Limited specialist professional knowledge of diabetes by staff in primary and community care, alongside inadequate patient self-management knowledge, led to inappropriate treatment and significant delays. This was compounded by restricted provision of care, characterised by poor access to services, in time and proximity, and poor continuity of care. Complexities in patient engagement, help-seeking, and illness-beliefs, further complicated the progression to unscheduled admissions.
Dedicated investment in primary care is needed to enhance provision of and access to services, promoting increased and earlier diabetes specialist team involvement, alongside training and use of technology and telemedicine to enhance existing care.
Background Anastomotic leak, a potentially deadly postoperative occurrence, particularly interests surgeons performing gastrointestinal procedures. We investigated incidence, cost, and impact on ...survival of anastomotic leak in gastrointestinal surgical procedures at an academic center. Study Design We conducted a chart review of American College of Surgeons NSQIP operative procedures with gastrointestinal anastomosis from January 1, 2003 through April 30, 2006. Each case with an American College of Surgeons NSQIP 30-day postoperative complication was systematically reviewed for evidence of anastomotic leak for 12 months after the operative date. We tracked patients for up to 10 years to determine survival. Morbidity, mortality, and cost for patients with gastrointestinal anastomotic leaks were compared with patients with anastomoses that remained intact. Results Unadjusted analyses revealed significant differences between patients who had anastomotic leaks develop and those who did not: morbidity (98.0% vs 28.4%; p < 0.0001), length of stay (13 vs 5 days; p ≤ 0.0001), 30-day mortality (8.4% vs 2.5%; p < 0.0001), long-term mortality (36.4% vs 20.0%; p ≤ 0.0001), and hospital costs (chi-square 2 = 359.8; p < 0.0001). Multivariable regression demonstrated that anastomotic leak was associated with congestive heart failure (odds ratio OR = 31.5; 95% CI, 2.6–381.4; p = 0.007), peripheral vascular disease (OR = 4.6; 95% CI, 1.0–20.5; p = 0.048), alcohol abuse (OR = 3.7; 95% CI, 1.6–8.3; p = 0.002), steroid use (OR = 2.3; 95% CI: 1.1–5.0; p = 0.027), abnormal sodium (OR = 0.4; 95% CI, 0.2–0.7; p = 0.002), weight loss (OR = 0.2; 95% CI, 0.06–0.7; p = 0.011), and location of anastomosis: rectum (OR = 14.0; 95% CI, 2.6–75.5; p = 0.002), esophagus (OR = 13.0; 95% CI, 3.6–46.2; p < 0.0001), pancreas (OR = 12.4; 95% CI, 3.3–46.2; p < 0.0001), small intestine (OR = 6.9; 95% CI, 1.8–26.4; p = 0.005), and colon (OR = 5.2; 95% CI, 1.5–17.7; p = 0.009). Conclusions Significant morbidity, mortality, and cost accompany gastrointestinal anastomotic leaks. Patients who experience an anastomotic leak have lower rates of survival at 30 days and long term.
Context. Chemically inhomogeneous populations are observed in most globular clusters, but not in open clusters. Cluster mass seems to play a key role in the existence of multiple populations. Aims. ...Studying the chemical homogeneity of the most massive open clusters is needed to better understand the mechanism of their formation and determine the mass limit under which clusters cannot host multiple populations. Here we studied NGC 6705, which is a young and massive open cluster located towards the inner region of the Milky Way. This cluster is located inside the solar circle. This makes it an important tracer of the inner disk abundance gradient. Methods. This study makes use of BVI and ri photometry and comparisons with theoretical isochrones to derive the age of NGC 6705. We study the density profile of the cluster and the mass function to infer the cluster mass. Based on abundances of the chemical elements distributed in the first internal data release of the Gaia-ESO Survey, we study elemental ratios and the chemical homogeneity of the red clump stars. Radial velocities enable us to study the rotation and internal kinematics of the cluster. Results. The estimated ages range from 250 to 316 Myr, depending on the adopted stellar model. Luminosity profiles and mass functions show strong signs of mass segregation. We derive the mass of the cluster from its luminosity function and from the kinematics, finding values between 3700 M⊙ and 11 000 M⊙. After selecting the cluster members from their radial velocities, we obtain a metallicity of Fe/H = 0.10 ± 0.06 based on 21 candidate members. Moreover, NGC 6705 shows no sign of the typical correlations or anti-correlations between Al, Mg, Si, and Na, which are expected in multiple populations. This is consistent with our cluster mass estimate, which is lower than the required mass limit proposed in the literature to develop multiple populations.
PDF
