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Sökning: WFRF:(Roder Martin Andreas)

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  • Dadaev, Tokhir, et al. (författare)
  • Fine-mapping of prostate cancer susceptibility loci in a large meta-analysis identifies candidate causal variants.
  • 2018
  • Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 9:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Prostate cancer is a polygenic disease with a large heritable component. A number of common, low-penetrance prostate cancer risk loci have been identified through GWAS. Here we apply the Bayesian multivariate variable selection algorithm JAM to fine-map 84 prostate cancer susceptibility loci, using summary data from a large European ancestry meta-analysis. We observe evidence for multiple independent signals at 12 regions and 99 risk signals overall. Only 15 original GWAS tag SNPs remain among the catalogue of candidate variants identified; the remainder are replaced by more likely candidates. Biological annotation of our credible set of variants indicates significant enrichment within promoter and enhancer elements, and transcription factor-binding sites, including AR, ERG and FOXA1. In 40 regions at least one variant is colocalised with an eQTL in prostate cancer tissue. The refined set of candidate variants substantially increase the proportion of familial relative risk explained by these known susceptibility regions, which highlights the importance of fine-mapping studies and has implications for clinical risk profiling.
  • Alikhani, B., et al. (författare)
  • Compton polarimetry with a 36-fold segmented HPGe-detector of the AGATA-type
  • 2012
  • Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - 0168-9002. ; 675, s. 144-154
  • Tidskriftsartikel (refereegranskat)abstract
    • The calibration of a highly-segmented AGATA-type HPGe-detector as a gamma-ray Compton polarimeter and a method for (quasi-)continuous angle Compton polarimetry are presented. The high granularity, combined with the large detection efficiency of the AGATA-type HPGe-crystals, offers a significant advantage for polarization measurements of gamma-radiation. A polarization-directional correlation experiment with gamma-rays from a Co-60 source with an activity of about 680 kBq was used to determine the polarization sensitivity of a single AGATA-type HPGe-crystal at 1173 and 1332 key and to demonstrate the method. The polarization measurement was based on segment information. In our set-up a polarization sensitivity of 19% at 1332 keV has been achieved.
  • Caesar, C., et al. (författare)
  • Beyond the neutron drip line: The unbound oxygen isotopes O-25 and O-26
  • 2013
  • Ingår i: Physical Review C - Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 88:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The very neutron-rich oxygen isotopes O-25 and O-26 are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from F-26 and F-27 at relativistic energies around 442 and 414 MeV/nucleon, respectively. From the kinematically complete measurement of the decay into O-24 plus one or two neutrons, the O-25 ground-state energy and width are determined, and upper limits for the O-26 ground-state energy and lifetime are extracted. In addition, the results provide indications for an excited state in O-26 at around 4 MeV. The experimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added.
  • Heine, M., et al. (författare)
  • Determination of the neutron-capture rate of C-17 for r-process nucleosynthesis
  • 2017
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985. ; 95:1, s. Article no 014613 -
  • Tidskriftsartikel (refereegranskat)abstract
    • With the (RB)-B-3-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of C-18 at a projectile energy around 425A MeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of C-17 into the ground state of C-18. Those data have been used to constrain theoretical calculations for transitions populating excited states in C-18. This allowed to derive the astrophysical cross section sigma(n gamma)*. accounting for the thermal population of C-17 target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures T-9
  • Vandebrouck, M., et al. (författare)
  • Effective proton-neutron interaction near the drip line from unbound states in F-25,F-26
  • 2017
  • Ingår i: Physical Review C. - 2469-9985. ; 96:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The F-26 nucleus, composed of a deeply bound pi 0d(5/2) proton and an unbound v0d(3/2) neutron on top of an O-24 core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a J(pi) = 1(1)(+) - 4(1)(+) multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The J(pi) = 1(1)(+), 2(1)(+), 4(1)(+) bound states have been determined, and only a clear identification of the J(pi) = 3(1)(+) is missing. Purpose: We wish to complete the study of the J(pi) = 1(1)(+) - 4(1)(+) multiplet in F-26, by studying the energy and width of the J(pi) = 3(1)(+) unbound state. The method was first validated by the study of unbound states in F-25, for which resonances were already observed in a previous experiment. Method: Radioactive beams of Ne-26 and Ne-27, produced at about 440AMeV by the fragment separator at the GSI facility were used to populate unbound states in F-25 and F-26 via one-proton knockout reactions on a CH2 target, located at the object focal point of the (RB)-B-3/LAND setup. The detection of emitted. rays and neutrons, added to the reconstruction of the momentum vector of the A - 1 nuclei, allowed the determination of the energy of three unbound states in F-25 and two in F-26. Results: Based on its width and decay properties, the first unbound state in F-25, at the relative energy of 49(9) keV, is proposed to be a J(pi) = 1/ 2(-) arising from a p1/2 proton- hole state. In F-26, the first resonance at 323(33) keV is proposed to be the J(pi) = 3(1)(+) member of the J(pi) = 1(1)(+) - 4(1)(+) multiplet. Energies of observed states in F-25,F-26 have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton- neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of F-26.
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