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- Hillairet, J., et al.
(författare)
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Recent progress on lower hybrid current drive and implications for ITER
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:7
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Tidskriftsartikel (refereegranskat)abstract
- The sustainment of steady-state plasmas in tokamaks requires efficient current drive systems. Lower hybrid current drive is currently the most efficient method to generate a continuous additional off-axis toroidal plasma current and to reduce the poloidal flux consumption during the plasma current ramp-up phase. The operation of the Tore Supra ITER-like lower hybrid (LH) launcher has demonstrated the capability to couple LH power at ITER-like power densities with very low reflected power during long pulses. In addition, the installation of eight 700 kW/CW klystrons at the LH transmitter has allowed increasing the total LH power in long-pulse scenarios. However, in order to achieve pure stationary LH-sustained plasmas, some R&D is needed to increase the reliability of all the systems and codes, from radio-frequency (RF) sources to plasma scenario prediction. The CEA/IRFM is addressing some of these issues by leading a R&D programme towards an ITER LH system and by the validation of an integrated LH modelling suite of codes. In 2011, the RF design of a mode converter was validated at a low power. A 500 kW/5 s RF window is currently under manufacture and will be tested at a high power in 2012 in collaboration with the National Fusion Research Institute. All of this work aims to reduce the operational risks associated with the ITER steady-state operations.
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| 2. |
- Hansbro, Philip M., et al.
(författare)
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Surveillance and analysis of avian influenza viruses, Australia
- 2010
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Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 16:12, s. 1896-1904
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Tidskriftsartikel (refereegranskat)abstract
- We investigated carriage of avian influenza viruses by wild birds in Australia, 2005-2008, to assess the risks to poultry industries and human health. We collected 21,858 (7,357 cloacal, 14,501 fecal) samples and detected 300 viruses, representing a detection rate of ≈1.4%. Rates were highest in autumn (March-May) and differed substantially between bird types, areas, and years. We typed 107 avian influenza viruses and identified 19 H5, 8 H7, and 16 H9 (40% of typed viruses). All were of low pathogenicity. These viruses formed clearly different phylogenetic clades to lineages from Eurasia or North America, suggesting the potential existence of Australian lineages. H7 viruses were similar to highly pathogenic H7 strains that caused outbreaks in poultry in Australia. Several periods of increased detection rates (numbers or subtypes of viruses) were identified. This study demonstrates the need for ongoing surveillance to detect emerging pathogenic strains and facilitate prevention of outbreaks.
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| 3. |
- Mattsson, Niklas, 1979, et al.
(författare)
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Association of brain amyloid-beta with cerebral perfusion and structure in Alzheimer's disease and mild cognitive impairment
- 2014
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 137, s. 1550-1561
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Tidskriftsartikel (refereegranskat)abstract
- Patients with Alzheimer's disease have reduced cerebral blood flow measured by arterial spin labelling magnetic resonance imaging, but it is unclear how this is related to amyloid-beta pathology. Using 182 subjects from the Alzheimer's Disease Neuroimaging Initiative we tested associations of amyloid-beta with regional cerebral blood flow in healthy controls (n = 51), early (n = 66) and late (n = 41) mild cognitive impairment, and Alzheimer's disease with dementia (n = 24). Based on the theory that Alzheimer's disease starts with amyloid-beta accumulation and progresses with symptoms and secondary pathologies in different trajectories, we tested if cerebral blood flow differed between amyloid-beta-negative controls and -positive subjects in different diagnostic groups, and if amyloid-beta had different associations with cerebral blood flow and grey matter volume. Global amyloid-beta load was measured by florbetapir positron emission tomography, and regional blood flow and volume were measured in eight a priori defined regions of interest. Cerebral blood flow was reduced in patients with dementia in most brain regions. Higher amyloid-beta load was related to lower cerebral blood flow in several regions, independent of diagnostic group. When comparing amyloid-beta-positive subjects with -negative controls, we found reductions of cerebral blood flow in several diagnostic groups, including in precuneus, entorhinal cortex and hippocampus (dementia), inferior parietal cortex (late mild cognitive impairment and dementia), and inferior temporal cortex (early and late mild cognitive impairment and dementia). The associations of amyloid-beta with cerebral blood flow and volume differed across the disease spectrum, with high amyloid-beta being associated with greater cerebral blood flow reduction in controls and greater volume reduction in late mild cognitive impairment and dementia. In addition to disease stage, amyloid-beta pathology affects cerebral blood flow across the span from controls to dementia patients. Amyloid-beta pathology has different associations with cerebral blood flow and volume, and may cause more loss of blood flow in early stages, whereas volume loss dominates in late disease stages.
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