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- Abel, I, et al.
(author)
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Overview of the JET results with the ITER-like wall
- 2013
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Journal article (peer-reviewed)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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- Nord, LC, et al.
(author)
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Analysis of oestrogen regulation of alpha-, beta- and gamma-secretase gene and protein expression in cultured human neuronal and glial cells
- 2010
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In: Neuro-degenerative diseases. - : S. Karger AG. - 1660-2862 .- 1660-2854. ; 7:6, s. 349-364
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Journal article (peer-reviewed)abstract
- <i>Background:</i> A key event in Alzheimer’s disease pathology is the proteolytic processing of amyloid precursor protein (APP), whereby β-amyloid (Aβ) peptide is produced. Oestrogen is acknowledged to influence cognitive function and has been shown to regulate the secretory metabolism of APP and decrease the production of Aβ, thereby protecting the brain from neurodegeneration. The mechanism for this effect is unknown. <i>Objective:</i> To investigate possible oestrogen regulation of the expression of the APP processing enzymes at the gene and/or protein level. <i>Methods:</i> The effects of oestrogen on gene and protein expression of α- (TACE and ADAM10), β- (BACE) and γ- (presenilin 1) secretases in cultured human fetal neurons and glial cells were studied. The RNase protection assay, gene expression microarray analysis and relative quantitative real-time PCR were used to analyse gene expression, while the protein expression and cellular localization of the secretases were studied by immunoblot and confocal microscopy. <i>Results:</i> Oestrogen is involved in the regulation of the gene expression of TACE and presenilin 1. Most importantly, BACE protein expression was downregulated by oestrogen treatment in mixed neuronal/glial cell cultures. Our results also show the cellular localization of the secretases in human neurons and glial cells, which has been thoroughly discussed in the light of the localization of APP processing. <i>Conclusion:</i> Our results indicate that oestrogen may affect APP processing directly by regulating the expression of the involved enzymes.
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- Romanelli, F, et al.
(author)
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Overview of the JET results
- 2011
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
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Journal article (peer-reviewed)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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