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- Sublet, J. -Ch., et al.
(författare)
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Neutron-induced damage simulations : Beyond defect production cross-section, displacement per atom and iron-based metrics
- 2019
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Ingår i: The European Physical Journal Plus. - : Springer Berlin/Heidelberg. - 2190-5444. ; 134:7
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Forskningsöversikt (refereegranskat)abstract
- Nuclear interactions can be the source of atomic displacement and post-short-term cascade annealing defects in irradiated structural materials. Such quantities are derived from, or can be correlated to, nuclear kinematic simulations of primary atomic energy distributions spectra and the quantification of the numbers of secondary defects produced per primary as a function of the available recoils, residual and emitted, energies. Recoils kinematics of neutral, residual, charged and multi-particle emissions are now more rigorously treated based on modern, complete and enhanced nuclear data parsed in state of the art processing tools. Defect production metrics are the starting point in this complex problem of correlating and simulating the behaviour of materials under irradiation, as direct measurements are extremely improbable. The multi-scale dimensions (nuclear-atomic-molecular-material) of the simulation process is tackled from the Fermi gradation to provide the atomic- and meso-scale dimensions with better metrics relying upon a deeper understanding and modelling capabilities of the nuclear level. Detailed, segregated primary knock-on-atom metrics are now available as the starting point of further simulation processes of isolated and clustered defects in material lattices. This allows more materials, incident energy ranges and particles, and irradiations conditions to be explored, with sufficient data to adequately cover both standard applications and novel ones, such as advanced-fission, accelerators, nuclear medicine, space and fusion. This paper reviews the theory, describes the latest methodologies and metrics, and provides recommendations for standard and novel approaches.
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- Denk, Thomas, et al.
(författare)
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Genomic landscape of the global oak phylogeny
- 2019
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; , s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- The tree of life is highly reticulate, with the history of population divergence emerging frompopulations of gene phylogenies that reflect histories of introgression, lineage sorting anddivergence. In this study, we investigate global patterns of oak diversity and test the hypothesisthat there are regions of the oak genome that are broadly informative about phylogeny. We utilize fossil data and restriction-site associated DNA sequencing (RAD-seq) for 632individuals representing nearly 250 Quercus species to infer a time-calibrated phylogeny ofthe world’s oaks. We use a reversible-jump Markov chain Monte Carlo method to reconstructshifts in lineage diversification rates, accounting for among-clade sampling biases. We thenmap the > 20 000 RAD-seq loci back to an annotated oak genome and investigate genomicdistribution of introgression and phylogenetic support across the phylogeny. Oak lineages have diversified among geographic regions, followed by ecological divergencewithin regions, in the Americas and Eurasia. Roughly 60% of oak diversity traces back to fourclades that experienced increases in net diversification, probably in response to climatic transitionsor ecological opportunity. The strong support for the phylogeny contrasts with high genomic heterogeneity in phylogeneticsignal and introgression. Oaks are phylogenomic mosaics, and their diversity may infact depend on the gene flow that shapes the oak genome.
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