| 51. |
- Buder, Sven, et al.
(författare)
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The GALAH+ survey : Third data release
- 2021
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 506:1, s. 150-201
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Tidskriftsartikel (refereegranskat)abstract
- The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the Milky Way. With this third data release of the Galactic Archaeology with HERMES (GALAH) survey, we publish 678 423 spectra for 588 571 mostly nearby stars (81.2 per cent of stars are within <2 kpc), observed with the HERMES spectrograph at the Anglo-Australian Telescope. This release (hereafter GALAH+ DR3) includes all observations from GALAH Phase 1 (bright, main, and faint survey, 70 per cent), K2-HERMES (17 per cent), TESS-HERMES (5 per cent), and a subset of ancillary observations (8 per cent) including the bulge and >75 stellar clusters. We derive stellar parameters Teff, log g, [Fe/H], vmic, vbroad, and vrad using our modified version of the spectrum synthesis code Spectroscopy Made Easy (sme) and 1D marcs model atmospheres. We break spectroscopic degeneracies in our spectrum analysis with astrometry from Gaia DR2 and photometry from 2MASS. We report abundance ratios [X/Fe] for 30 different elements (11 of which are based on non-LTE computations) covering five nucleosynthetic pathways. We describe validations for accuracy and precision, flagging of peculiar stars/measurements and recommendations for using our results. Our catalogue comprises 65 per cent dwarfs, 34 per cent giants, and 1 per cent other/unclassified stars. Based on unflagged chemical composition and age, we find 62 per cent young low-α, 9 per cent young high-α, 27 per cent old high-α, and 2 per cent stars with [Fe/H] ≤ −1. Based on kinematics, 4 per cent are halo stars. Several Value-Added-Catalogues, including stellar ages and dynamics, updated after Gaia eDR3, accompany this release and allow chrono-chemodynamic analyses, as we showcase.
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| 52. |
- Buder, Sven, et al.
(författare)
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The GALAH Survey : chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+DR3 and Gaia eDR3
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 510:2, s. 2407-2436
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Tidskriftsartikel (refereegranskat)abstract
- Since the advent of Gaia astrometry, it is possible to identify massive accreted systems within the Galaxy through their unique dynamical signatures. One such system, Gaia-Sausage-Enceladus (GSE), appears to be an early ‘building block’ given its virial mass >1010M⊙ at infall (z ∼ 1−3). In order to separate the progenitor population from the background stars, we investigate its chemical properties with up to 30 element abundances from the GALAH+ Survey Data Release 3 (DR3). To inform our choice of elements for purely chemically selecting accreted stars, we analyse 4164 stars with low-α abundances and halo kinematics. These are most different to the Milky Way stars for abundances of Mg, Si, Na, Al, Mn, Fe, Ni, and Cu. Based on the significance of abundance differences and detection rates, we apply Gaussian mixture models to various element abundance combinations. We find the most populated and least contaminated component, which we confirm to represent GSE, contains 1049 stars selected via [Na/Fe] versus [Mg/Mn] in GALAH+ DR3. We provide tables of our selections and report the chrono-chemodynamical properties (age, chemistry, and dynamics). Through a previously reported clean dynamical selection of GSE stars, including 30<√JR/kpckms−1<55, we can characterize an unprecedented 24 abundances of this structure with GALAH+ DR3. With our chemical selection we characterize the dynamical properties of the GSE, for example mean √JR/kpckms−1=26+9−14. We find only (29±1) per cent of the GSE stars within the clean dynamical selection region. Our methodology will improve future studies of accreted structures and their importance for the formation of the Milky Way.
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| 53. |
- Casey, Cameron P, et al.
(författare)
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Postoperative delirium is associated with increased plasma neurofilament light.
- 2020
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 143:1, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- While delirium is associated with cognitive decline and dementia, there is limited evidence to support causality for this relationship. Clarification of how delirium may cause cognitive decline, perhaps through evidence of contemporaneous neuronal injury, would enhance plausibility for a causal relationship. Dose-dependence of neuronal injury with delirium severity would further enhance the biological plausibility for this relationship. We tested whether delirium is associated with neuronal injury in 114 surgical patients recruited to a prospective biomarker cohort study. Patients underwent perioperative testing for changes in neurofilament light, a neuronal injury biomarker, as well as a panel of 10 cytokines, with contemporaneous assessment of delirium severity and incidence. A subset of patients underwent preoperative MRI. Initially we confirmed prior reports that neurofilament light levels correlated with markers of neurodegeneration [hippocampal volume (ΔR2 = 0.129, P = 0.015)] and white matter changes including fractional anisotropy of white matter (ΔR2 = 0.417, P < 0.001) with similar effects on mean, axial and radial diffusivity) in our cohort and that surgery was associated with increasing neurofilament light from preoperative levels [mean difference (95% confidence interval, CI) = 0.240 (0.178, 0.301) log10 (pg/ml), P < 0.001], suggesting putative neuronal injury. Next, we tested the relationship with delirium. Neurofilament light rose more sharply in participants with delirium compared to non-sufferers [mean difference (95% CI) = 0.251 (0.136, 0.367) log10 (pg/ml), P < 0.001]. This relationship showed dose-dependence, such that neurofilament light rose proportionately to delirium severity (ΔR2 = 0.199, P < 0.001). Given that inflammation is considered an important driver of postoperative delirium, next we tested whether neurofilament light, as a potential marker of neurotoxicity, may contribute to the pathogenesis of delirium independent of inflammation. From a panel of 10 cytokines, the pro-inflammatory cytokine IL-8 exhibited a strong correlation with delirium severity (ΔR2 = 0.208, P < 0.001). Therefore, we tested whether the change in neurofilament light contributed to delirium severity independent of IL-8. Neurofilament light was independently associated with delirium severity after adjusting for the change in inflammation (ΔR2 = 0.040, P = 0.038). These data suggest delirium is associated with exaggerated increases in neurofilament light and that this putative neurotoxicity may contribute to the pathogenesis of delirium itself, independent of changes in inflammation.
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| 54. |
- Crump, Casey, et al.
(författare)
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Early-Life Cardiorespiratory Fitness and Long-term Risk of Prostate Cancer
- 2020
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Ingår i: Cancer Epidemiology, Biomarkers and Prevention. - 1055-9965 .- 1538-7755. ; 29:11, s. 2187-2194
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Tidskriftsartikel (refereegranskat)abstract
- Background: Adolescence is a period of rapid prostatic growth, yet is understudied for susceptibility for future risk of prostate cancer. We examined cardiorespiratory fitness (CRF) in late adolescence in relation to long-term prostate cancer risk.Methods: A population-based cohort study was conducted of all 699,125 Swedish military conscripts during 1972–1985 (97%–98% of 18-year-old men) in relation to risk of prostate cancer overall, aggressive prostate cancer, and prostate cancer mortality during 1998–2017 (ages 50–65 years). CRF was measured by maximal aerobic workload, and prostate cancer was ascertained using the National Prostate Cancer Register. Muscle strength was examined as a secondary predictor.Results: In 38.8 million person-years of follow-up, 10,782 (1.5%) men were diagnosed with prostate cancer. Adjusting for sociodemographic factors, height, weight, and family history of prostate cancer, high CRF was associated with a slightly increased risk of any prostate cancer [highest vs. lowest quintile: incidence rate ratio (IRR), 1.10; 95% CI, 1.03–1.19; P = 0.008], but was neither significantly associated with aggressive prostate cancer (1.01; 0.85–1.21; P = 0.90) nor prostate cancer mortality (1.24; 0.73–2.13; P = 0.42). High muscle strength also was associated with a modestly increased risk of any prostate cancer (highest vs. lowest quintile: IRR, 1.14; 95% CI, 1.07–1.23; P < 0.001), but neither with aggressive prostate cancer (0.88; 0.74–1.04; P = 0.14) nor prostate cancer mortality (0.81; 0.48–1.37; P = 0.43).Conclusions: High CRF or muscle strength in late adolescence was associated with slightly increased future risk of prostate cancer, possibly related to increased screening, but neither with risk of aggressive prostate cancer nor prostate cancer mortality.Impact: These findings illustrate the importance of distinguishing aggressive from indolent prostate cancer and assessing for potential detection bias.
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| 55. |
- Crump, Casey, et al.
(författare)
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Risks of alcohol and drug use disorders in prostate cancer survivors : a national cohort study
- 2023
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Ingår i: JNCI CANCER SPECTRUM. - : Oxford University Press (OUP). - 2515-5091. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Prostate cancer (PC) survivors may potentially use substances to cope with psychological distress or poorly controlled physical symptoms. Little is known, however, about the long-term risks of alcohol use disorder (AUD) or drug use disorders in men with PC.Methods: A national cohort study was conducted in Sweden of 180 189 men diagnosed with PC between 1998 and 2017 and 1 801 890 age-matched population-based control men. AUD and drug use disorders were ascertained from nationwide records through 2018. Cox regression was used to compute hazard ratios (HRs) while adjusting for sociodemographic factors and prior psychiatric disorders. Subanalyses examined differences by PC treatment from 2005 to 2017.Results: Men with high-risk PC had increased risks of both AUD (adjusted HR = 1.44, 95% confidence interval [CI] = 1.33 to 1.57) and drug use disorders (adjusted HR = 1.93, 95% CI = 1.67 to 2.24). Their AUD risk was highest in the first year and was no longer significantly elevated 5 years after PC diagnosis, whereas their drug use disorders risk remained elevated 10 years after PC diagnosis (adjusted HR = 2.26, 95% CI = 1.45 to 3.52), particularly opioid use disorder (adjusted HR = 3.07, 95% CI = 1.61 to 5.84). Those treated only with androgen-deprivation therapy had the highest risks of AUD (adjusted HR = 1.91, 95% CI = 1.62 to 2.25) and drug use disorders (adjusted HR = 2.23, 95% CI = 1.70 to 2.92). Low- or intermediate-risk PC was associated with modestly increased risks of AUD (adjusted HR = 1.38, 95% CI = 1.30 to 1.46) and drug use disorders (adjusted HR = 1.19, 95% CI = 1.06 to 1.34).Conclusions: In this large cohort, men with PC had significantly increased risks of both AUD and drug use disorders, especially those with high-risk PC and treated only with androgen-deprivation therapy. PC survivors need long-term psychosocial support and timely detection and treatment of AUD and drug use disorders.
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| 56. |
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| 57. |
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| 58. |
- Gao, Xudong, et al.
(författare)
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The GALAH survey : a new constraint on cosmological lithium and Galactic lithium evolution from warm dwarf stars
- 2020
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966 .- 1745-3925 .- 1745-3933. ; 497:1, s. L30-L34
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Tidskriftsartikel (refereegranskat)abstract
- Lithium depletion and enrichment in the cosmos is not yet well understood. To help tighten constraints on stellar and Galactic evolution models, we present the largest high-resolution analysis of Li abundances A(Li) to date, with results for over 100000 GALAH (Galactic Archeology with HERMES) field stars spanning effective temperatures 5900K≲Teff≲7000K and metallicities −3 ≲ [Fe/H] ≲ +0.5. We separated these stars into two groups, on the warm and cool sides of the so-called Li dip, a localized region of the Kiel diagram wherein lithium is severely depleted. We discovered that stars in these two groups show similar trends in the A(Li)–[Fe/H] plane, but with a roughly constant offset in A(Li) of 0.4dex, the warm group having higher Li abundances. At [Fe/H]≳−0.5, a significant increase in Li abundance with increasing metallicity is evident in both groups, signalling the onset of significant Galactic production. At lower metallicity, stars in the cool group sit on the Spite plateau, showing a reduced lithium of around 0.4dex relative to the primordial value predicted from big bang nucleosynthesis (BBN). However, stars in the warm group between [Fe/H] = −1.0 and −0.5 form an elevated plateau that is largely consistent with the BBN prediction. This may indicate that these stars in fact preserve the primordial Li produced in the early Universe.
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| 59. |
- Hamel, Jean-François, et al.
(författare)
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Range extension and first record of the deep-sea brittle star Ophiactis abyssicola (Echinodermata: Ophiuroidea) in Canadian waters
- 2022
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Ingår i: Journal of the Marine Biological Association of the United Kingdom. - : Cambridge University Press (CUP). - 0025-3154 .- 1469-7769. ; (2021) 101:8, s. 1181-1184
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the first records of the brittle star Ophiactis abyssicola in Canadian waters and range extensions of up to 1900 km in the Northwest Atlantic from previously known locations. Samples were collected off northern Labrador and the northern portion of insular Newfoundland (eastern Canada) at 433 and 1097 m depths, respectively. This newly recorded species of brittle star from the bathyal zone off Newfoundland and Labrador adds to the marine biodiversity of Canada and to the general distribution knowledge of O. abyssicola.
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| 60. |
- Hayden, Michael R., et al.
(författare)
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The GALAH survey : chemical clocks
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 517:4, s. 5325-5339
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Tidskriftsartikel (refereegranskat)abstract
- We present the first large-scale study that demonstrates how ages can be determined for large samples of stars through Galactic chemical evolution. Previous studies found that the elemental abundances of a star correlate directly with its age and metallicity. Using this knowledge, we derive ages for 214 577 stars in GALAH DR3 using only overall metallicities and chemical abundances. Stellar ages are estimated via the machine learning algorithm XGBoost for stars belonging to the Milky Way disc with metallicities in the range -1 < [Fe/H] < 0.5, using main-sequence turn-off stars as our training set. We find that stellar ages for the bulk of GALAH DR3 are precise to 1-2 Gyr using this method. With these ages, we replicate many recent results on the age-kinematic trends of the nearby disc, including the solar neighbourhood's age-velocity dispersion relationship and the larger global velocity dispersion relations of the disc found using Gaia and GALAH. These results show that chemical abundance variations at a given birth radius are small, and that strong chemical tagging of stars directly to birth clusters may prove difficult with our current elemental abundance precision. Our results highlight the need to measure abundances for as many nucleosynthetic production sites as possible in order to estimate reliable ages from chemistry. Our methods open a new door into studies of the kinematic structure and evolution of the disc, as ages may potentially be estimated to a precision of 1-2 Gyr for a large fraction of stars in existing spectroscopic surveys.
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