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- Tabiri, S, et al.
(author)
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- 2021
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swepub:Mat__t
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- Bravo, L, et al.
(author)
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- 2021
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swepub:Mat__t
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- Fenstermacher, M.E., et al.
(author)
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DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
- 2022
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In: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
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Journal article (peer-reviewed)abstract
- DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.
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- Stroth, U., et al.
(author)
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Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development
- 2022
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
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Journal article (peer-reviewed)abstract
- An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.
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- Mendoza, Pablo A, et al.
(author)
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Oral anticoagulation for patients with atrial fibrillation in the ED : RE-LY AF registry analysis.
- 2022
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In: Journal of Thrombosis and Thrombolysis. - : Springer Nature. - 0929-5305 .- 1573-742X. ; 53:1, s. 74-82
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Journal article (peer-reviewed)abstract
- Oral anticoagulation (OAC) reduces stroke risk in patients with atrial fibrillation (AF). We sought to determine predictors of OAC initiation in AF patients presenting to the emergency department (ED). Secondary analysis of the RE-LY AF registry which enrolled individuals from 47 countries between 2007 and 2011 who presented to an ED with AF and followed them for 1 year. A total of 4149 patients with AF as their primary diagnosis who were not already taking OAC and had a CHA2DS2-VASc ≥ 1 for men or ≥ 2 for women were included in this analysis. Of these individuals, 26.8% were started on OAC (99.2% vitamin K antagonists) in the ED and 29.8% were using OAC one year later. Factors associated with initiating OAC in the ED included: specialist consultation (relative risk [RR] 1.84, 95%CI 1.44-2.36), rheumatic heart disease (RR 1.60, 95%CI 1.29-1.99), persistence of AF at ED discharge (RR 1.33, 95%CI 1.18-1.50), diabetes mellitus (RR 1.32, 95%CI 1.19-1.47), and hospital admission (RR 1.30, 95%CI 1.14-1.47). Heart failure (RR 0.83, 95%CI 0.74-0.94), antiplatelet agents (RR 0.77, 95%CI 0.69-0.84), and dementia (RR 0.61, 95%CI 0.40-0.94) were inversely associated with OAC initiation. Patients taking OAC when they left the ED were more likely using OAC at 1-year (RR 2.81, 95%CI 2.55-3.09) and had lower rates of death (RR 0.55, 95%CI 0.38-0.79) and stroke (RR 0.59, 95%CI 0.37-0.96). In patients with AF presenting to the ED, prompt initiation of OAC and specialist involvement are associated with a greater use of OAC 1 year later and may result in improved clinical outcomes.
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- Pandey, Arjun K., et al.
(author)
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Sodium-glucose co-transporter inhibitors and atrial fibrillation : A systematic review and meta-analysis of randomized controlled trials
- 2021
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In: Journal of the American Heart Association. - 2047-9980. ; 10:17
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Journal article (peer-reviewed)abstract
- BACKGROUND: Sodium-glucose co-transporter (SGLT) inhibitors reduce cardiovascular outcomes including mortality in several populations; however, their effect on atrial fibrillation/flutter (AF) remains unclear. Our objective was to determine whether SGLT inhibitors reduce AF and whether a history of AF modifies the effect of SGLT inhibitors on the composite of heart failure hospitalization or cardiovascular death. METHODS AND RESULTS: We searched MEDLINE, Embase, and CENTRAL to March 2021. Pairs of reviewers identified randomized controlled trials that compared an SGLT inhibitor with placebo or no therapy. We pooled data using RevMan 5.4.1, assessed risk of bias using the Cochrane tool, and determined the overall quality of evidence using Grades of Recommendation, Assessment, Development and Evaluation. Thirty-one eligible trials reported on AF events (75 279 participants, mean age 62 years, 35.0% women). Moderate quality evidence supported a lower risk of serious AF events with SGLT inhibitors (1.1% versus 1.5%; risk ratio 0.75 [95% CI, 0.66–0.86]; I2=0%). A similar reduction in total AF events was also noted with SGLT inhibitors. Three trials reported on heart failure hospitalization/cardiovascular death stratified by a baseline history of AF (18 832 participants, mean age 66 years, 38.1% women); in patients with a history of AF, SGLT inhibitors resulted in a lower risk in the composite of heart failure hospitalization or cardiovascular death (hazard ratio, 0.70 [95% CI, 0.57–0.85]; I2=0%)—similar to the effect estimate for patients without AF, P value for interaction: 1.00. CONCLUSIONS: SGLT inhibitors may reduce AF events and likely reduce heart failure hospitalization/cardiovascular death to a similar extent in patients with and without AF.
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