| 1. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 2. |
- Labit, B., et al.
(författare)
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Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:8
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Institute of Physics Publishing. All rights reserved. Within the EUROfusion MST1 work package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (ne,sep/nG ∼ 0.3), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a double null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.
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| 3. |
- Coda, S., et al.
(författare)
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Physics research on the TCV tokamak facility: From conventional to alternative scenarios and beyond
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Tidskriftsartikel (refereegranskat)abstract
- The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, to exploratory plasmas driven by theoretical insight, exploiting the device's unique shaping capabilities. Disruption avoidance by real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic and radiation triggers. Runaway generation with high-Z noble-gas injection and runaway dissipation by subsequent Ne or Ar injection were studied for model validation. The new 1 MW neutral beam injector has expanded the parameter range, now encompassing ELMy H-modes in an ITER-like shape and nearly non-inductive H-mode discharges sustained by electron cyclotron and neutral beam current drive. In the H-mode, the pedestal pressure increases modestly with nitrogen seeding while fueling moves the density pedestal outwards, but the plasma stored energy is largely uncorrelated to either seeding or fueling. High fueling at high triangularity is key to accessing the attractive small edge-localized mode (type-II) regime. Turbulence is reduced in the core at negative triangularity, consistent with increased confinement and in accord with global gyrokinetic simulations. The geodesic acoustic mode, possibly coupled with avalanche events, has been linked with particle flow to the wall in diverted plasmas. Detachment, scrape-off layer transport, and turbulence were studied in L- and H-modes in both standard and alternative configurations (snowflake, super-X, and beyond). The detachment process is caused by power 'starvation' reducing the ionization source, with volume recombination playing only a minor role. Partial detachment in the H-mode is obtained with impurity seeding and has shown little dependence on flux expansion in standard single-null geometry. In the attached L-mode phase, increasing the outer connection length reduces the in-out heat-flow asymmetry. A doublet plasma, featuring an internal X-point, was achieved successfully, and a transport barrier was observed in the mantle just outside the internal separatrix. In the near future variable-configuration baffles and possibly divertor pumping will be introduced to investigate the effect of divertor closure on exhaust and performance, and 3.5 MW ECRH and 1 MW neutral beam injection heating will be added.
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| 4. |
- Edlmann, E, et al.
(författare)
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Dex-CSDH randomised, placebo-controlled trial of dexamethasone for chronic subdural haematoma: report of the internal pilot phase
- 2019
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1, s. 5885-
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Tidskriftsartikel (refereegranskat)abstract
- The Dex-CSDH trial is a randomised, double-blind, placebo-controlled trial of dexamethasone for patients with a symptomatic chronic subdural haematoma. The trial commenced with an internal pilot, whose primary objective was to assess the feasibility of multi-centre recruitment. Primary outcome data collection and safety were also assessed, whilst maintaining blinding. We aimed to recruit 100 patients from United Kingdom Neurosurgical Units within 12 months. Trial participants were randomised to a 2-week course of dexamethasone or placebo in addition to receiving standard care (which could include surgery). The primary outcome measure of the trial is the modified Rankin Scale at 6 months. This pilot recruited ahead of target; 100 patients were recruited within nine months of commencement. 47% of screened patients consented to recruitment. The primary outcome measure was collected in 98% of patients. No safety concerns were raised by the independent data monitoring and ethics committee and only five patients were withdrawn from drug treatment. Pilot trial data can inform on the design and resource provision for substantive trials. This internal pilot was successful in determining recruitment feasibility. Excellent follow-up rates were achieved and exploratory outcome measures were added to increase the scientific value of the trial.
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| 7. |
- Grace, O. M., et al.
(författare)
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Opinion Botanical Monography in the Anthropocene
- 2021
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385. ; 26:5, s. 433-441
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Tidskriftsartikel (refereegranskat)abstract
- Unprecedented changes in the Earth?s biota are prompting urgent efforts to describe and conserve plant diversity. For centuries, botanical monographs ? comprehensive systematic treatments of a family or genus ? have been the gold standard for disseminating scientific information to accelerate research. The lack of a monograph compounds the risk that undiscovered species become extinct before they can be studied and conserved. Progress towards estimating the Tree of Life and digital information resources now bring even the most ambitious monographs within reach. Here, we recommend best practices to complete monographs urgently, especially for tropical plant groups under imminent threat or with expected socioeconomic benefits. We also highlight the renewed relevance and potential impact of monographies for the understanding, sustainable use, and conservation of biodiversity.
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| 8. |
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| 9. |
- Kümpers, B. M. C., et al.
(författare)
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The significance of meristic changes in the flower of Sapotaceae
- 2016
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Ingår i: Botanical journal of the Linnean Society. - 0024-4074 .- 1095-8339. ; 180, s. 161-192
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Tidskriftsartikel (refereegranskat)abstract
- Sapotaceae belongs to the heterogeneous order Ericales and exhibits extensive diversity in floral morphology. Although pentamery is widespread and probably the ancestral condition, some clades are extremely variable in merism, with fluctuations between tetramery to hexamery and octomery, affecting different floral organs to different degrees. We assessed the different states of merism in Sapotaceae to determine the evolution of this character among different clades. The floral morphology and development of nine species from eight genera were investigated using scanning electron microscopy (SEM). Furthermore, floral characters related to merism were mapped onto a phylogenetic tree to analyse the distribution and evolutionary significance of merism in the family. Developmental evidence shows that changes in merism are linked to a concerted multiplication of organs among whorls and an increase in whorls through the displacement of organs. Although pentamery is reconstructed as the ancestral condition, a reduction to tetramery or an increase to a higher merism (mainly hexamery or octomery) has evolved at least five times in the family. Fluctuations in merism between different whorls are not random but occur in a coordinated pattern, presenting strong synapomorphies for selected clades. Octomery has evolved at least twice, in Isonandreae from tetramery and in Sapoteae-Mimusopinae from pentamery. Hexamery has evolved at least three times, independently in Northia, the Palaquium clade of Isonandreae and derived from octomery in Sapoteae-Mimusopinae. Three possibilities of merism increase have been identified in Sapotaceae: (1) a concerted increase affecting all organs more or less equally (Palaquium clade of Isonandreae, Sapoteae); (2) a coordinated increase in petals, stamens and mostly carpels without effect on sepals (Labourdonnaisia, Payena–Madhuca clade of Isonandreae); (3) an increase in carpels independently of other organs (Burckella, Letestua, Labramia, etc.). A major shift affecting all Sapotaceae, except Isonandreae, is the sterilization or loss of the antesepalous stamen whorl. The presence of two fertile stamen whorls in Isonandreae indicates a possible reversal or a retained plesiomorphy. In a number of genera, stamens are secondarily increased independently of changes in merism. Descriptions of flowers listing only organ numbers are thus misleading in the inference of evolutionary relationships, as they do not differentiate between changes in merism affecting the number of perianth whorls and other changes affecting the androecium, such as sterilization, loss or occasional doubling of antepetalous stamens.
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