| 1. |
- Chaboyer, B., et al.
(författare)
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Testing Metal-poor Stellar Models and Isochrones with HST Parallaxes of Metal-poor Stars
- 2017
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Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 835:2
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Tidskriftsartikel (refereegranskat)abstract
- Hubble Space Telescope (HST) fine guidance sensor observations were used to obtain parallaxes of eight metal-poor ([Fe/H] < -1.4) stars. The parallaxes of these stars determined by the new Hipparcos reduction average 17% accuracy, in contrast to our new HST parallaxes, which average 1% accuracy and have errors on the individual parallaxes ranging from 85 to 144 mu as. These parallax data were combined with HST Advanced Camera for Surveys photometry in the F606W and F814W filters to obtain the absolute magnitudes of the stars with an accuracy of 0.02-0.03 mag. Six of these stars are on the main sequence (MS) (with -2.7 < [Fe/H] < -1.8) and are suitable for testing metal-poor stellar evolution models and determining the distances to metal-poor globular clusters (GCs). Using the abundances obtained by O'Malley et al., we find that standard stellar models using the VandenBerg & Clem color transformation do a reasonable job of matching five of the MS stars, with HD 54639 ([Fe/H] = -2.5) being anomalous in its location in the color-magnitude diagram. Stellar models and isochrones were generated using a Monte Carlo analysis to take into account uncertainties in the models. Isochrones that fit the parallax stars were used to determine the distances and ages of nine GCs (with -2.4 <= [Fe/H] <= -1.9). Averaging together the age of all nine clusters led to an absolute age of the oldest, most metal-poor GCs of 12.7 +/- 1.0 Gyr, where the quoted uncertainty takes into account the known uncertainties in the stellar models and isochrones, along with the uncertainty in the distance and reddening of the clusters.
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| 2. |
- Gillespie, B. M., et al.
(författare)
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Worldwide incidence of surgical site infections in general surgical patients: A systematic review and meta-analysis of 488,594 patients
- 2021
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Ingår i: International Journal of Surgery. - : Ovid Technologies (Wolters Kluwer Health). - 1743-9191. ; 95
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Tidskriftsartikel (refereegranskat)abstract
- Background: Establishing worldwide incidence of general surgical site infections (SSI) is imperative to understand the extent of the condition to assist decision-makers to improve the planning and delivery of surgical care. This systematic review and meta-analysis aimed to estimate the worldwide incidence of SSI and identify associated factors in adult general surgical patients. Materials and methods: A systematic review was undertaken using MEDLINE (Ovid), CINAHL (EBSCO), EMBASE (Elsevier) and the Cochrane Library to identify cross-sectional, cohort and observational studies reporting SSI incidence or prevalence. Studies of less than 50 participants were excluded. Data extraction and quality appraisal were undertaken independently by two review authors. The primary outcome was cumulative incidence of SSI occurring up to 30 days postoperative. The secondary outcome was the severity/depth of SSI. The I2 statistic was used to explore heterogeneity. Random effects models were used in the presence of substantial heterogeneity. Subgroup, meta-regression sensitivity analyses were used to explore the sources of heterogeneity. Publication bias was assessed using Hunter's plots and Egger's regression test. Results: Of 2091 publications retrieved, 62 studies were included. Of these, 57 were included in the meta-analysis across six anatomical locations with 488,594 patients. The pooled 30-day cumulative incidence of SSI was 11% (95% CI 10%–13%). No prevalence data were identified. SSI rates varied across anatomical location, surgical approach, and priority (i.e., planned, emergency). Multivariable meta-regression showed SSI is significantly associated with duration of surgery (estimate 1.01, 95% CI 1.00–1.02, P = .014). Conclusions: and Relevance: 11 out of 100 general surgical patients are likely to develop an infection 30 days after surgery. Given the imperative to reduce the burden of harm caused by SSI, high-quality studies are warranted to better understand the patient and related risk factors associated with SSI. © 2021 IJS Publishing Group Ltd
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| 3. |
- Milone, A. P., et al.
(författare)
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The ACS survey of Galactic globular clusters XII. Photometric binaries along the main sequence
- 2012
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 540
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Tidskriftsartikel (refereegranskat)abstract
- Context. The fraction of binary stars is an important ingredient to interpret globular cluster dynamical evolution and their stellar population. Aims. We investigate the properties of main-sequence binaries measured in a uniform photometric sample of 59 Galactic globular clusters that were observed by HST WFC/ACS as a part of the Globular Cluster Treasury project. Methods. We measured the fraction of binaries and the distribution of mass-ratio as a function of radial location within the cluster, from the central core to beyond the half-mass radius. We studied the radial distribution of binary stars, and the distribution of stellar mass ratios. We investigated monovariate relations between the fraction of binaries and the main parameters of their host clusters. Results. We found that in nearly all the clusters, the total fraction of binaries is significantly smaller than the fraction of binaries in the field, with a few exceptions only. Binary stars are significantly more centrally concentrated than single MS stars in most of the clusters studied in this paper. The distribution of the mass ratio is generally flat (for mass-ratio parameter q > 0.5). We found a significant anti-correlation between the binary fraction in a cluster and its absolute luminosity (mass). Some, less significant correlation with the collisional parameter, the central stellar density, and the central velocity dispersion are present. There is no statistically significant relation between the binary fraction and other cluster parameters. We confirm the correlation between the binary fraction and the fraction of blue stragglers in the cluster.
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| 4. |
- D’Orazi, Valentina, et al.
(författare)
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The GALAH survey : tracing the Milky Way’s formation and evolution through RR Lyrae stars
- 2024
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Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 531:1, s. 137-162
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Tidskriftsartikel (refereegranskat)abstract
- Stellar mergers and accretion events have been crucial in shaping the evolution of the Milky Way (MW). These events have been dynamically identified and chemically characterized using red giants and main-sequence stars. RR Lyrae (RRL) variables can play a crucial role in tracing the early formation of the MW since they are ubiquitous, old (t ≥ 10 Gyr) low-mass stars and accurate distance indicators. We exploited Data Release 3 of the GALAH survey to identify 78 field RRLs suitable for chemical analysis. Using synthetic spectra calculations, we determined atmospheric parameters and abundances of Fe, Mg, Ca, Y, and Ba. Most of our stars exhibit halo-like chemical compositions, with an iron peak around [Fe/H] ≈ −1.40, and enhanced Ca and Mg content. Notably, we discovered a metal-rich tail, with [Fe/H] values ranging from −1 to approximately solar metallicity. This sub-group includes almost 1/4 of the sample, it is characterized by thin disc kinematics and displays sub-solar α-element abundances, marginally consistent with the majority of the MW stars. Surprisingly, they differ distinctly from typical MW disc stars in terms of the s-process elements Y and Ba. We took advantage of similar data available in the literature and built a total sample of 535 field RRLs for which we estimated kinematical and dynamical properties. We found that metal-rich RRLs (1/3 of the sample) likely represent an old component of the MW thin disc. We also detected RRLs with retrograde orbits and provided preliminary associations with the Gaia–Sausage–Enceladus, Helmi, Sequoia, Sagittarius, and Thamnos stellar streams.
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| 5. |
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| 6. |
- Gillespie, B. M., et al.
(författare)
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Economic case for intraoperative interventions to prevent surgical-site infection
- 2017
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Ingår i: British Journal of Surgery. - : Oxford University Press (OUP). - 0007-1323 .- 1365-2168. ; 104:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: Surgical-site infection (SSI) occurs in 1–10 per cent of all patients undergoing surgery; rates can be higher depending on the type of surgery. The aim of this review was to establish whether (or not) surgical hand asepsis, intraoperative skin antisepsis and selected surgical dressings are cost-effective in SSI prevention, and to examine the quality of reporting. Methods: The authors searched MEDLINE via Ovid, CINAHL via EBSCO, Cochrane Central and Scopus databases systematically from 1990 to 2016. Included were RCTs and quasi-experimental studies published in English, evaluating the economic impact of interventions to prevent SSI relative to surgical hand and skin antisepsis, and wound dressings. Characteristics and results of included studies were extracted using a standard data collection tool. Study and reporting quality were assessed using SIGN and CHEERS checklists. Results: Across the three areas of SSI prevention, the combined searches identified 1214 articles. Of these, five health economic studies evaluating the cost-effectiveness of selected surgical dressings were eligible. Study authors concluded that the interventions being assessed were cost-effective, or were potentially cost-saving. Still, there is high uncertainty around the decision to adopt these dressings/devices in practice. The studies' reporting quality was reasonable; three reported at least 15 of the 24 CHEERS items appropriately. Assessment of methodological quality found that two studies were considered to be of high quality. Conclusion: With few economic studies undertaken in this area, the cost-effectiveness of these strategies is unclear. Incorporating economic evaluations alongside RCTs will help towards evidence-informed decisions. © 2017 BJS Society Ltd Published by John Wiley & Sons Ltd
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| 7. |
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| 8. |
- Tobiano, G., et al.
(författare)
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Development and validation of a survey designed to measure patient experience of and preference for surgical wound care discharge education: A pilot study
- 2023
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Ingår i: Journal of Tissue Viability. - 0965-206X. ; 32:3, s. 442-448
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Tidskriftsartikel (refereegranskat)abstract
- Aim of the study: To develop and undertake validation testing of a survey designed to measure patients' experiences of and preferences for surgical wound care discharge education.Materials and methods: A literature review and content analysis was undertaken on patients' experiences of and preferences for surgical wound care discharge education. Four themes were uncovered in the literature (wound care discharge education, preferences for discharge education delivery, participation in wound care decisions and patient ability to manage their surgical wound to prevent wound complications), which guided item generation. Three types of validity testing occurred including: 1) face validity testing by the research team; 2) content validity testing (using Delphi study) with an international panel of experts including patients, clinicians and researchers; and 3) content validity (using pilot-testing) of the survey with seven patients from the target population.Results: Initially 106 items were generated from the literature, and of these, 55 items were subjected to content validity testing by an international panel of 41 experts. After two Delphi rounds, 18 items were retained. Most patients provided limited and very minor feedback during pilot-testing. However, pilot-testing resulted in a revised survey administration plan to deliver the survey via telephone, including adding prompts and preambles to items.
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