| 1. |
- Yavorskij, V., et al.
(författare)
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TF ripple effects on the NBI deuteron confinement in JET
- 2007
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Ingår i: 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts. - 9781622763344 ; , s. 876-879
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Konferensbidrag (refereegranskat)abstract
- Ripple induced reduction of the fluxes of deuterium neutrals in the 5-40 keV energy range from the plasma mid-plane was observed in recent JET experiments. The maximum observed reduction of D0 fluxes due to ripple is approximately 50 % and occurs at energies above 30 keV. In positive shear plasmas without ICRH ripple reduction of D0 fluxes vanishes at energies below 10 keV. However, in the case of plasmas with low or reversed shear core, increased D0 fluxes were observed for energies below 10-20 keV in the presence of additional ripple and ICRH heating. Interpretive modeling of the deuterium neutral emission that accounts for the superbanana ripple diffusion of NBI ions is in reasonable agreement with measurements at least for the scenarios without ICRH. Note that ripples may essentially effect the fast ion confinement in ITER where TF ripple magnitude at the outer separatrix is expected to be δ ∼ 0.5%.
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| 2. |
- Bieling, Peter, et al.
(författare)
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Reconstitution of a microtubule plus-end tracking system in vitro
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 450:7172, s. 1100-1105
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Tidskriftsartikel (refereegranskat)abstract
- The microtubule cytoskeleton is essential to cell morphogenesis. Growing microtubule plus ends have emerged as dynamic regulatory sites in which specialized proteins, called plus-end-binding proteins (+TIPs), bind and regulate the proper functioning of microtubules. However, the molecular mechanism of plus-end association by +TIPs and their ability to track the growing end are not well understood. Here we report the in vitro reconstitution of a minimal plus-end tracking system consisting of the three fission yeast proteins Mal3, Tip1 and the kinesin Tea2. Using time-lapse total internal reflection fluorescence microscopy, we show that the EB1 homologue Mal3 has an enhanced affinity for growing microtubule end structures as opposed to the microtubule lattice. This allows it to track growing microtubule ends autonomously by an end recognition mechanism. In addition, Mal3 acts as a factor that mediates loading of the processive motor Tea2 and its cargo, the Clip170 homologue Tip1, onto the microtubule lattice. The interaction of all three proteins is required for the selective tracking of growing microtubule plus ends by both Tea2 and Tip1. Our results dissect the collective interactions of the constituents of this plus-end tracking system and show how these interactions lead to the emergence of its dynamic behaviour. We expect that such in vitro reconstitutions will also be essential for the mechanistic dissection of other plus-end tracking systems.
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