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- Wiedorn, Max O., et al.
(författare)
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Megahertz serial crystallography
- 2018
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The new European X-ray Free-Electron Laser is the first X-ray free-electron laser capable of delivering X-ray pulses with a megahertz inter-pulse spacing, more than four orders of magnitude higher than previously possible. However, to date, it has been unclear whether it would indeed be possible to measure high-quality diffraction data at megahertz pulse repetition rates. Here, we show that high-quality structures can indeed be obtained using currently available operating conditions at the European XFEL. We present two complete data sets, one from the well-known model system lysozyme and the other from a so far unknown complex of a beta-lactamase from K. pneumoniae involved in antibiotic resistance. This result opens up megahertz serial femtosecond crystallography (SFX) as a tool for reliable structure determination, substrate screening and the efficient measurement of the evolution and dynamics of molecular structures using megahertz repetition rate pulses available at this new class of X-ray laser source.
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| 2. |
- Amanullah, Rahman, et al.
(författare)
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Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 μm
- 2015
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 453:3, s. 3300-3328
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Tidskriftsartikel (refereegranskat)abstract
- We present ultraviolet (UV) observations of six nearby Type Ia supernovae (SNe Ia) obtained with the Hubble Space Telescope, three of which were also observed in the near-IR (NIR) with Wide-Field Camera 3. UV observations with the Swift satellite, as well as ground-based optical and NIR data provide complementary information. The combined data set covers the wavelength range 0.2-2 mu m. By also including archival data of SN 2014J, we analyse a sample spanning observed colour excesses up to E(B - V) = 1.4 mag. We study the wavelength-dependent extinction of each individual SN and find a diversity of reddening laws when characterized by the total-to-selective extinction R-V. In particular, we note that for the two SNe with E(B - V) greater than or similar to 1 mag, for which the colour excess is dominated by dust extinction, we find R-V = 1.4 +/- 0.1 and R-V = 2.8 +/- 0.1. Adding UV photometry reduces the uncertainty of fitted R-V by similar to 50 per cent allowing us to also measure R-V of individual low-extinction objects which point to a similar diversity, currently not accounted for in the analyses when SNe Ia are used for studying the expansion history of the Universe.
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| 3. |
- Targownik, Laura E, et al.
(författare)
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Inflammatory bowel disease and the risk of fracture after controlling for FRAX.
- 2013
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Ingår i: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. - : Wiley. - 1523-4681. ; 28:5, s. 1007-13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Subjects with inflammatory bowel disease (IBD) are at increased risk for hip and other major osteoporotic fractures. However, previous analyses have not fully accounted for differences in bone mineral density (BMD) and other clinical factors that affect the risk of fracture. The World Health Organization Fracture Risk Assessment tool (FRAX®) can be used to predict the 10-year fracture riskfrom BMD and clinical risk factors. METHODS: A population based database containing clinical information on all IBD subjects in the province of Manitoba, Canada, was linked with the Manitoba Bone Mineral Density Database, which contains results of all dual X-ray absorptiometry (DXA) scans in the province. FRAX probabilities were calculated for all subjects aged50 years or more undergoing baseline DXA testing. Subjects were followed for occurrence of major osteoporotic fractures (MOF; hip, clinical spine, wrist, humerus). Cox proportional hazards models were used to determine whether IBD was independently predictive of MOF or hip fracture. RESULTS: After controlling for FRAX fracture probability computed with BMD, IBD was not associated with a significantly increased risk for MOF (HR 1.12, 95%CI 0.83-1.55) but was associated with an increased risk for hip fracture (HR 2.14, 95%CI 1.26-3.65).The addition of femoral neck T-score to FRAX probability without knowledge of BMD had a negligible effect on the estimated hazard ratios for IBD, suggesting that IBD mediates any effect on fracture risk independently of femoral neck BMD CONCLUSION: After controlling for FRAX probability, subjects with IBD are not at an increased risk for overall MOF, but may be at increased risk of hip fracture. © 2012 American Society for Bone and Mineral Research.
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