| 1. |
- Berthomier, M., et al.
(författare)
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Alfven : magnetosphere-ionosphere connection explorers
- 2012
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Ingår i: Experimental astronomy. - Dordrecht : Springer. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 445-489
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Tidskriftsartikel (refereegranskat)abstract
- The aurorae are dynamic, luminous displays that grace the night skies of Earth's high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between the solar wind-driven magnetosphere and the ionospheric environment at the top of Earth's atmosphere play a central role. In this Auroral Acceleration Region (AAR) persistent electric fields directed along the magnetic field accelerate magnetospheric electrons to the high energies needed to excite luminosity when they hit the atmosphere. The "ideal magnetohydrodynamics" description of space plasmas which is useful in much of the magnetosphere cannot be used to understand the AAR. The AAR has been studied by a small number of single spacecraft missions which revealed an environment rich in wave-particle interactions, plasma turbulence, and nonlinear acceleration processes, acting on a variety of spatio-temporal scales. The pioneering 4-spacecraft Cluster magnetospheric research mission is now fortuitously visiting the AAR, but its particle instruments are too slow to allow resolve many of the key plasma physics phenomena. The Alfv,n concept is designed specifically to take the next step in studying the aurora, by making the crucial high-time resolution, multi-scale measurements in the AAR, needed to address the key science questions of auroral plasma physics. The new knowledge that the mission will produce will find application in studies of the Sun, the processes that accelerate the solar wind and that produce aurora on other planets.
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| 2. |
- Breed, Martin, 1981-, et al.
(författare)
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Pollen diversity matters : revealing the neglected effect of pollen diversity on fitness in fragmented landscapes
- 2012
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 21:24, s. 5955-5968
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Tidskriftsartikel (refereegranskat)abstract
- Few studies have documented the impacts of habitat fragmentation on plant mating patterns together with fitness. Yet, these processes require urgent attention to better understand the impact of contemporary landscape change on biodiversity and for guiding native plant genetic resource management. We examined these relationships using the predominantly insect-pollinated Eucalyptus socialis. Progeny were collected from trees located in three increasingly disturbed landscapes in southern Australia and were planted out in common garden experiments. We show that individual mating patterns were increasingly impacted by lower conspecific density caused by habitat fragmentation. We determined that reduced pollen diversity probably has effects over and above those of inbreeding on progeny fitness. This provides an alternative mechanistic explanation for the indirect density dependence often inferred between conspecific density and offspring fitness.
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| 3. |
- Hånell, Anders, et al.
(författare)
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Genetic Deletion and Pharmacological Inhibition of Nogo-66 Receptor Impairs Cognitive Outcome after Traumatic Brain Injury in Mice
- 2010
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Ingår i: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 27:7, s. 1297-1309
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Tidskriftsartikel (refereegranskat)abstract
- Functional recovery is markedly restricted following traumatic brain injury (TBI), partly due to myelin-associated inhibitors including Nogo-A, myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMgp), that all bind to the Nogo-66 receptor-1 (NgR1). In previous studies, pharmacological neutralization of both Nogo-A and MAG improved outcome following TBI in the rat, and neutralization of NgR1 improved outcome following spinal cord injury and stroke in rodent models. However, the behavioral and histological effects of NgR1 inhibition have not previously been evaluated in TBI. We hypothesized that NgR1 negatively influences behavioral recovery following TBI, and evaluated NgR1(-/-) mice (NgR1(-/-) study) and, in a separate study, soluble NgR1 infused intracerebroventricularly immediately post-injury to neutralize NgR1 (sNgR1 study) following TBI in mice using a controlled cortical impact (CCI) injury model. In both studies, motor function, TBI-induced loss of tissue, and hippocampal beta-amyloid immunohistochemistry were not altered up to 5 weeks post-injury. Surprisingly, cognitive function (as evaluated with the Morris water maze at 4 weeks post-injury) was significantly impaired both in NgR1(-/-) mice and in mice treated with soluble NgR1. In the sNgR1 study, we evaluated hippocampal mossy fiber sprouting using the Timm stain and found it to be increased at 5 weeks following TBI. Neutralization of NgR1 significantly increased mossy fiber sprouting in sham-injured animals, but not in brain-injured animals. Our data suggest a complex role for myelin-associated inhibitors in the behavioral recovery process following TBI, and urge caution when inhibiting NgR1 in the early post-injury period.
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