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- 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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- Cohen, G, et al.
(författare)
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Perinatal exposure to nicotine causes deficits associated with a loss of nicotinic receptor function
- 2005
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 102:10, s. 3817-3821
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the role played by β2-containing neuronal nicotinic receptors [nicotinic acetylcholine receptors (nAChRs)] in mediating nicotine's side effects in the fetus and newborn. Pregnant WT and mutant mice lacking the β2 nAChR subunit were implanted with osmotic minipumps that delivered either water or a controlled dose of nicotine. Subsequently, we compared the development of the sympathoadrenal system and breathing and arousal reflexes of offspring shortly after birth, a period of increased vulnerability to nicotine exposure. Newborn WT pups exposed to nicotine exhibited all of the deficits associated with maternal tobacco and nicotine use, and linked to poor neonatal outcome: growth restriction, unstable breathing, and impaired arousal and catecholamine biosynthesis. Remarkably similar deficits were detected in pups lacking β2-containing nAChRs. Loss-of-function of these nAChRs consequently reproduces with astonishing fidelity many of the abnormalities caused by perinatal nicotine exposure. We propose that the underlying mechanisms of nicotine's detrimental side effects on a range of crucial defensive reflexes involve loss of function of nAChR subtypes, possibly via activity-dependent desensitization.
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