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  • Schofield, James P. R., et al. (författare)
  • Stratification of asthma phenotypes by airway proteomic signatures
  • 2019
  • Ingår i: Journal of Allergy and Clinical Immunology. - Elsevier. - 0091-6749 .- 1097-6825. ; 144:1, s. 70-82
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Stratification by eosinophil and neutrophil counts increases our understanding of asthma and helps target therapy, but there is room for improvement in our accuracy in prediction of treatment responses and a need for better understanding of the underlying mechanisms. Objective: We sought to identify molecular subphenotypes of asthma defined by proteomic signatures for improved stratification. Methods: Unbiased label-free quantitative mass spectrometry and topological data analysis were used to analyze the proteomes of sputum supernatants from 246 participants (206 asthmatic patients) as a novel means of asthma stratification. Microarray analysis of sputum cells provided transcriptomics data additionally to inform on underlying mechanisms. Results: Analysis of the sputum proteome resulted in 10 clusters (ie, proteotypes) based on similarity in proteomic features, representing discrete molecular subphenotypes of asthma. Overlaying granulocyte counts onto the 10 clusters as metadata further defined 3 of these as highly eosinophilic, 3 as highly neutrophilic, and 2 as highly atopic with relatively low granulocytic inflammation. For each of these 3 phenotypes, logistic regression analysis identified candidate protein biomarkers, and matched transcriptomic data pointed to differentially activated underlying mechanisms. Conclusion: This study provides further stratification of asthma currently classified based on quantification of granulocytic inflammation and provided additional insight into their underlying mechanisms, which could become targets for novel therapies.
  • Bedding, Timothy R., et al. (författare)
  • A multi-site campaign to measure solar-like oscillations in Procyon. II. mode frequencies
  • 2010
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 713:2, s. 935-949
  • Tidskriftsartikel (refereegranskat)abstract
    • We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with 11 telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the power spectrum. Stacking the power spectrum in a so-called echelle diagram reveals two clear ridges, which we identify with even and odd values of the angular degree (l = 0 and 2, and l = 1 and 3, respectively). We interpret a strong, narrow peak at 446 mu Hz that lies close to the l = 1 ridge as a mode with mixed character. We show that the frequencies of the ridge centroids and their separations are useful diagnostics for asteroseismology. In particular, variations in the large separation appear to indicate a glitch in the sound-speed profile at an acoustic depth of similar to 1000 s. We list frequencies for 55 modes extracted from the data spanning 20 radial orders, a range comparable to the best solar data, which will provide valuable constraints for theoretical models. A preliminary comparison with published models shows that the offset between observed and calculated frequencies for the radial modes is very different for Procyon than for the Sun and other cool stars. We find the mean lifetime of the modes in Procyon to be 1.29(-0.49)(+0.55) days, which is significantly shorter than the 2-4 days seen in the Sun.
  • Kos, Janez, et al. (författare)
  • The GALAH survey : The data reduction pipeline
  • 2017
  • Ingår i: Monthly Notices of the Royal Astronomical Society. - Oxford University Press. - 0035-8711. ; 464:2, s. 1259-1281
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the data reduction procedures being used by the GALactic Archeology with Hermes (GALAH) survey, carried out with the HERMES fibre-fed, multi-object spectrograph on the 3.9-m Anglo-Australian Telescope. GALAH is a unique survey, targeting 1 million stars brighter than magnitude V = 14 at a resolution of 28 000 with a goal to measure the abundances of 29 elements. Such a large number of high-resolution spectra necessitate the development of a reduction pipeline optimized for speed, accuracy, and consistency.We outline the design and structure of the IRAF-based reduction pipeline that we developed, specifically for GALAH, to produce fully calibrated spectra aimed for subsequent stellar atmospheric parameter estimation. The pipeline takes advantage of existing IRAF routines and other readily available software so as to be simple to maintain, testable, and reliable. A radial velocity and stellar atmospheric parameter estimator code is also presented, which is used for further data analysis and yields a useful verification of the reduction quality. We have used this estimator to quantify the data quality of GALAH for fibre cross-talk level (≲0.5 per cent) and scattered light (~5 counts in a typical 20 min exposure), resolution across the field, sky spectrum properties, wavelength solution reliability (better than 1 kms-1 accuracy), and radial velocity precision.
  • Sharma, Sanjib, et al. (författare)
  • The K2-HERMES Survey : age and metallicity of the thick disc
  • 2019
  • Ingår i: Monthly notices of the Royal Astronomical Society. - OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 490:4, s. 5335-5352
  • Tidskriftsartikel (refereegranskat)abstract
    • Asteroseismology is a promising tool to study Galactic structure and evolution because it can probe the ages of stars. Earlier attempts comparing seismic data from the Kepler satellite with predictions from Galaxy models found that the models predicted more low-mass stars compared to the observed distribution of masses. It was unclear if the mismatch was due to inaccuracies in the Galactic models, or the unknown aspects of the selection function of the stars. Using new data from the K2 mission, which has a well-defined selection function, we find that an oldmetal-poor thick disc, as used in previous Galactic models, is incompatible with the asteroseismic information. We use an importance-sampling framework, which takes the selection function into account, to fit for the metallicities of a population synthesis model using spectroscopic data. We show that spectroscopic measurements of [Fe/H] and [alpha/Fe] elemental abundances from the GALAH survey indicate a mean metallicity of log (Z/Z(circle dot)) = -0.16 for the thick disc. Here Z is the effective solar-scaled metallicity, which is a function of [Fe/H] and [alpha/Fe]. With the revised disc metallicities, for the first time, the theoretically predicted distribution of seismic masses show excellent agreement with the observed distribution of masses. This indirectly verifies that the asteroseismic mass scaling relation is good to within five per cent. Assuming the asteroseismic scaling relations are correct, we estimate the mean age of the thick disc to be about 10 Gyr, in agreement with the traditional idea of an old alpha-enhanced thick disc.
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