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- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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- Giustozzi, M., et al.
(författare)
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Safety of Anticoagulation in Patients Treated with Urgent Reperfusion for Ischemic Stroke Related to Atrial Fibrillation
- 2020
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Ingår i: Stroke. - 0039-2499. ; 51:8, s. 2347-2354
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Tidskriftsartikel (refereegranskat)abstract
- Background and Purpose: The optimal timing for starting oral anticoagulant after an ischemic stroke related to atrial fibrillation remains a challenge, mainly in patients treated with systemic thrombolysis or mechanical thrombectomy. We aimed at assessing the incidence of early recurrence and major bleeding in patients with acute ischemic stroke and atrial fibrillation treated with thrombolytic therapy and/or thrombectomy, who then received oral anticoagulants for secondary prevention. Methods: We combined the dataset of the RAF and the RAF-NOACs (Early Recurrence and Major Bleeding in Patients With Acute Ischemic Stroke and Atrial Fibrillation Treated With Non-Vitamin K Oral Anticoagulants) studies, which were prospective observational studies carried out from January 2012 to March 2014 and April 2014 to June 2016, respectively. We included consecutive patients with acute ischemic stroke and atrial fibrillation treated with either vitamin K antagonists or nonvitamin K oral anticoagulants. Primary outcome was the composite of stroke, transient ischemic attack, symptomatic systemic embolism, symptomatic cerebral bleeding, and major extracerebral bleeding within 90 days from the inclusion. Treated-patients were propensity matched to untreated-patients in a 1:1 ratio after stratification by baseline clinical features. Results: A total of 2159 patients were included, 564 (26%) patients received acute reperfusion therapies. After the index event, 505 (90%) patients treated with acute reperfusion therapies and 1287 of 1595 (81%) patients untreated started oral anticoagulation. Timing of starting oral anticoagulant was similar in reperfusion-treated and untreated patients (median 7.5 versus 7.0 days, respectively). At 90 days, the primary study outcome occurred in 37 (7%) patients treated with reperfusion and in 146 (9%) untreated patients (odds ratio, 0.74 [95% CI, 0.50-1.07]). After propensity score matching, risk of primary outcome was comparable between the 2 groups (odds ratio, 1.06 [95% CI, 0.53-2.02]). Conclusions: Acute reperfusion treatment did not influence the risk of early recurrence and major bleeding in patients with atrial fibrillation-related acute ischemic stroke, who started on oral anticoagulant. © 2020 Georg Thieme Verlag. All rights reserved.
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| 8. |
- Paciaroni, M., et al.
(författare)
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Timing of initiation of oral anticoagulants in patients with acute ischemic stroke and atrial fibrillation comparing posterior and anterior circulation strokes
- 2020
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Ingår i: European Stroke Journal. - : SAGE Publications. - 2396-9873 .- 2396-9881.
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The aim of this study in patients with acute posterior ischaemic stroke (PS) and atrial fibrillation (AF) was to evaluate (1) the risks of recurrent ischaemic event and severe bleeding and (2) these risks in relation with oral anticoagulant therapy (OAT) and its timing. Materials and Methods: Patients with PS were prospectively included; the outcome events of these patients were compared with those of patients with anterior stroke (AS) which were taken from previous registries. The primary outcome was the composite of stroke recurrence, transient ischaemic attack, symptomatic systemic embolism, symptomatic cerebral bleeding and major extracranial bleeding occurring within 90 days from acute stroke. Results: A total of 2470 patients were available for the analysis: 473 (19.1%) with PS and 1997 (80.9%) with AS. Over 90 days, 213 (8.6%) primary outcome events were recorded: 175 (8.7%) in patients with AS and 38 (8.0%) in those with PS. In patients who initiated OAT within 2 days, the primary outcome occurred in 5 out of 95 patients (5.3%) with PS compared to 21 out of 373 patients (4.3%) with AS (OR 1.07; 95% CI 0.39-2.94). In patients who initiated OAT between days 3 and 7, the primary outcome occurred in 3 out of 103 patients (2.9%) with PS compared to 26 out of 490 patients (5.3%) with AS (OR 0.54; 95% CI 0.16-1.80). Discussion: our findings suggest that, when deciding the time to initiate oral anticoagulation, the location of stroke, either anterior or posterior, does not predict the risk of outcome events. Conclusions: Patients with PS or AS and AF appear to have similar risks of ischaemic or haemorrhagic events at 90 days with no difference concerning the timing of initiation of OAT.
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| 9. |
- Luigi, Lorenzini, et al.
(författare)
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Gray matter network properties show distinct associations with CSF p-tau 181 levels and amyloid status in individuals without dementia.
- 2022
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Ingår i: Aging brain. - : Elsevier BV. - 2589-9589. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Gray matter networks are altered with amyloid accumulation in the earliest stage of AD, and are associated with decline throughout the AD spectrum. It remains unclear to what extent gray matter network abnormalities are associated with hyperphosphorylated-tau (p-tau). We studied the relationship of cerebrospinal fluid (CSF) p-tau181 with gray matter networks in non-demented participants from the European Prevention of Alzheimer's Dementia (EPAD) cohort, and studied dependencies on amyloid and cognitive status. Gray matter networks were extracted from baseline structural 3D T1w MRI. P-tau181 and abeta were measured with the Roche cobas Elecsys System. We studied the associations of CSF biomarkers levels with several network's graph properties. We further studied whether the relationships of p-tau 181 and network measures were dependent on amyloid status and cognitive stage (CDR). We repeated these analyses for network properties at a regional level, where we averaged local network values across cubes within each of 116 areas as defined by the automated anatomical labeling (AAL) atlas. Amyloid positivity was associated with higher network size and betweenness centrality, and lower gamma, clustering and small-world coefficients. Higher CSF p-tau 181 levels were related to lower betweenness centrality, path length and lambda coefficients (all p<0.01). Three-way interactions between p-tau181, amyloid status and CDR were found for path length, lambda and clustering (all p<0.05): Cognitively unimpaired amyloid-negative participants showed lower path length and lambda values with higher CSF p-tau181 levels. Amyloid-positive participants with impaired cognition demonstrated lower clustering coefficients in association to higher CSF p-tau181 levels. Our results suggest that alterations in gray matter network clustering coefficient is an early and specific event in AD.
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| 10. |
- Weisen, H., et al.
(författare)
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Isotope dependence of energy, momentum and particle confinement in tokamaks
- 2020
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Ingår i: Journal of Plasma Physics. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 86:5
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Tidskriftsartikel (refereegranskat)abstract
- The isotope dependence of plasma transport will have a significant impact on the performance of future D-T experiments in JET and ITER and eventually on the fusion gain and economics of future reactors. In preparation for future D-T operation on JET, dedicated experiments and comprehensive transport analyses were performed in H, D and H-D mixed plasmas. The analysis of the data has demonstrated an unexpectedly strong and favourable dependence of the global confinement of energy, momentum and particles in ELMy H-mode plasmas on the atomic mass of the main ion species, the energy confinement time scaling as tau(E) similar to A(0.5) (Maggi et al., Plasma Phys. Control. Fusion, vol. 60, 2018, 014045; JET Team, Nucl. Fusion, vol. 39, 1999, pp. 1227-1244), i.e. opposite to the expectations based only on local gyro-Bohm (GB) scaling, tau(E) similar to A(-0.5), and stronger than in the commonly used H-mode scaling for the energy confinement (Saibene et al., Nucl. Fusion, vol. 39, 1999, 1133; ITER Physics Basis, Nucl. Fusion, vol. 39, 1999, 2175). The scaling of momentum transport and particle confinement with isotope mass is very similar to that of energy transport. Nonlinear local GENE gyrokinetic analysis shows that the observed anti-GB heat flux is accounted for if collisions, ExB shear and plasma dilution with low-Z impurities (Be-9) are included in the analysis (E and B are, respectively the electric and magnetic fields). For L-mode plasmas a weaker positive isotope scaling tau(E) similar to A(0.14) has been found in JET (Maggi et al., Plasma Phys. Control. Fusion, vol. 60, 2018, 014045), similar to ITER97-L scaling (Kaye et al., Nucl. Fusion, vol. 37, 1997, 1303). Flux-driven quasi-linear gyrofluid calculations using JETTO-TGLF in L-mode show that local GB scaling is not followed when stiff transport (as is generally the case for ion temperature gradient modes) is combined with an imposed boundary condition taken from the experiment, in this case predicting no isotope dependence. A dimensionless identity plasma pair in hydrogen and deuterium L-mode plasmas has demonstrated scale invariance, confirming that core transport physics is governed, as expected, by the 4 dimensionless parameters rho*, nu*, beta, q (normalised ion Larmor radius, collisionality, plasma pressure and safety factor) consistently with global quasi-linear gyrokinetic TGLF calculations (Maggi et al., Nucl. Fusion, vol. 59, 2019, 076028). We compare findings in JET with those in different devices and discuss the possible reasons for the different isotope scalings reported from different devices. The diversity of observations suggests that the differences may result not only from differences affecting the core, e.g. heating schemes, but are to a large part due to differences in device-specific edge and wall conditions, pointing to the importance of better understanding and controlling pedestal and edge processes.
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