| 1. |
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Overview of the JET results
- 2015
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 55:10
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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| 3. |
- Romanelli, F, et al.
(författare)
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Overview of the JET results
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
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Tidskriftsartikel (refereegranskat)abstract
- Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy H-mode operation at 4.5 MA. The high confinement hybrid scenario has been extended to high triangularity, lower ρ*and to pulse lengths comparable to the resistive time. The steady-state scenario has also been extended to lower ρ*and ν*and optimized to simultaneously achieve, under stationary conditions, ITER-like values of all other relevant normalized parameters. A dedicated helium campaign has allowed key aspects of plasma control and H-mode operation for the ITER non-activated phase to be evaluated. Effective sawtooth control by fast ions has been demonstrated with3He minority ICRH, a scenario with negligible minority current drive. Edge localized mode (ELM) control studies using external n = 1 and n = 2 perturbation fields have found a resonance effect in ELM frequency for specific q95values. Complete ELM suppression has, however, not been observed, even with an edge Chirikov parameter larger than 1. Pellet ELM pacing has been demonstrated and the minimum pellet size needed to trigger an ELM has been estimated. For both natural and mitigated ELMs a broadening of the divertor ELM-wetted area with increasing ELM size has been found. In disruption studies with massive gas injection up to 50% of the thermal energy could be radiated before, and 20% during, the thermal quench. Halo currents could be reduced by 60% and, using argon/deuterium and neon/deuterium gas mixtures, runaway electron generation could be avoided. Most objectives of the ITER-like ICRH antenna have been demonstrated; matching with closely packed straps, ELM resilience, scattering matrix arc detection and operation at high power density (6.2 MW m-2) and antenna strap voltages (42 kV). Coupling measurements are in very good agreement with TOPICA modelling. © 2011 IAEA, Vienna.
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| 4. |
- Michel, M., et al.
(författare)
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Small-molecule activation of OGG1 increases oxidative DNA damage repair by gaining a new function
- 2022
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Ingår i: Science. - Stockholm : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 376:6600, s. 1471-1476
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative DNA damage is recognized by 8-oxoguanine (8-oxoG) DNA glycosylase 1 (OGG1), which excises 8-oxoG, leaving a substrate for apurinic endonuclease 1 (APE1) and initiating repair. Here, we describe a small molecule (TH10785) that interacts with the phenylalanine-319 and glycine-42 amino acids of OGG1, increases the enzyme activity 10-fold, and generates a previously undescribed b,d-lyase enzymatic function. TH10785 controls the catalytic activity mediated by a nitrogen base within its molecular structure. In cells, TH10785 increases OGG1 recruitment to and repair of oxidative DNA damage. This alters the repair process, which no longer requires APE1 but instead is dependent on polynucleotide kinase phosphatase (PNKP1) activity. The increased repair of oxidative DNA lesions with a small molecule may have therapeutic applications in various diseases and aging. © 2022 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works
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| 5. |
- Arrizabalaga, O., et al.
(författare)
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High expression of MKP1/DUSP1 counteracts glioma stem cell activity and mediates HDAC inhibitor response
- 2017
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Ingår i: Oncogenesis. - : Springer Science and Business Media LLC. - 2157-9024. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The elucidation of mechanisms involved in resistance to therapies is essential to improve the survival of patients with malignant gliomas. A major feature possessed by glioma cells that may aid their ability to survive therapy and reconstitute tumors is the capacity for self-renewal. We show here that glioma stem cells (GSCs) express low levels of MKP1, a dual-specificity phosphatase, which acts as a negative inhibitor of JNK, ERK1/2, and p38 MAPK, while induction of high levels of MKP1 expression are associated with differentiation of GSC. Notably, we find that high levels of MKP1 correlate with a subset of glioblastoma patients with better prognosis and overall increased survival. Gain of expression studies demonstrated that elevated MKP1 impairs self-renewal and induces differentiation of GSCs while reducing tumorigenesis in vivo. Moreover, we identified that MKP1 is epigenetically regulated and that it mediates the anti-tumor activity of histone deacetylase inhibitors (HDACIs) alone or in combination with temozolomide. In summary, this study identifies MKP1 as a key modulator of the interplay between GSC self-renewal and differentiation and provides evidence that the activation of MKP1, through epigenetic regulation, might be a novel therapeutic strategy to overcome therapy resistance in glioblastoma.
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| 6. |
- Perez Von Thun, C., et al.
(författare)
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Study of fast-ion transport induced by fishbones on JET
- 2012
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 52:9, s. 094010-
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Tidskriftsartikel (refereegranskat)abstract
- The impact of fishbone oscillations onto a confined fast-ion population is simulated for a JET plasma and benchmarked against experiment quantitatively with the help of neutron rate measurements. The transient drops in volume integrated neutron emission are found to be mainly caused by the spatial redistribution of the (neutral beam injected) fast-ion population confined in the plasma rather than by fast-ion loss. The simulations yield a quadratic dependence of the neutron drop on the fishbone amplitude. It is found that the simulations are able to correctly reproduce the magnitude of the experimentally observed drop in volume integrated neutron emission to within a factor 2. Furthermore, frequency chirping is found to be important. Omitting the fishbone frequency chirp in the simulations reduces the magnitude of the neutron rate drop (and hence fast-ion redistribution) to about half its original value.
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| 7. |
- von Thun, C. Perez, et al.
(författare)
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MeV-range fast ion losses induced by fishbones on JET
- 2010
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 50:8, s. 084009-
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Tidskriftsartikel (refereegranskat)abstract
- Energy and pitch angle resolved measurements of highly energetic (megaelectronvolt (MeV) range) suprathermal ions ejected from the plasma through interaction with fishbone oscillations are presented. The measurements are obtained with a 2D scintillator probe diagnostic installed on JET, which is designed to detect lost ions only above a certain energy threshold (E-min,E- D similar to 200 keV). In the case reported here the lost ions are identified as fast protons which had been accelerated to high energies by ICRF minority heating. The energy of the lost protons (similar to 0.5-4 MeV) is approximately one order of magnitude higher than the energy of the injected beam ions (maximum 130 keV) driving the fishbone. Losses arriving at the probe are enhanced by about a factor 10-20 with respect to MHD-quiescent levels, and are found to increase quadratically with the fishbone amplitude. Using a number of simplifying assumptions, numerical simulations have been performed which combine the HAGIS, MISHKA and SELFO codes (where the distribution function predicted by SELFO has been validated against neutral particle analyser measurements). The losses are found to originate from orbit stochastic diffusion of trapped protons near the plasma boundary or from counter-passing protons deep in the plasma core, which transit under the influence of the fishbone into an unconfined trapped orbit. The simulations show further that the losses are of non-resonant type. The simulated energy and pitch angle distribution of the losses, the temporal behaviour of the losses during a fishbone cycle and the scaling of the losses with the fishbone amplitude are compared with experiment. The simulation results are mostly in broad agreement with experiment, but some of the predictions could not be reconciled with experiment using this model.
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| 8. |
- von Thun, C. Perez, et al.
(författare)
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Numerical simulation of fast ion loss detector measurements for fishbones on JET
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 51:5, s. 053003-
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Tidskriftsartikel (refereegranskat)abstract
- A synthetic diagnostic model for the simulation of energy and pitch angle resolved measurements of fast ion losses obtained by 2D scintillation-type detectors is presented and subsequently tested on a JET discharge with fishbones (previously documented in Perez von Thun et al 2010 Nucl. Fusion 50 084009). The simulated energy and pitch angle distributions at the detector are found to be in excellent agreement with the measurements. The simulations further suggest that nearly all the fast ion losses take place in the early growth phase of the fishbone cycle, and reach their maximum well ahead of the magnetic perturbation peak.
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| 10. |
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