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- Goren, L, et al.
(författare)
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Ductile Deformation of Passive Margins : A New Mechanism for Subduction Initiation
- 2008
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 113:B8, s. B08411-
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Tidskriftsartikel (refereegranskat)abstract
- [1] The onset of subduction at passive margins has been extensively investigated and debated. However, the force constellations and mechanisms that enable the development of a subduction system from a passive margin remain unclear. This study presents new insights into the conditions and processes by which lateral density differences between oceanic and continental lithospheres in passive margins may lead to initiation of a low-angle subduction system. The presented study consists of (1) analytical calculations of flow fields generated in passive margins, and (2) analogue experiments of mature passive margins performed in a centrifuge. The analytical formulation predicts temporal and spatial evolution of an interface between the oceanic and continental lithospheres, and demonstrates that oceanic underthrusting may occur by rotation of this interface. The analogue experiments show that incipient subduction may develop by ductile deformation within the lithosphere, involving no sliding along the ocean-continent interface, so that the frictional resistance between the plates need not be overcome. The force induced by the negative buoyancy of the oceanic plate with respect to the asthenosphere, is found to be in some cases irrelevant to subduction nucleation. Results of both the analogue experiments and the analytical calculation are compared to the south-east Australian passive margin, and show an excellent fit to its geometry and stress distribution. The proposed mechanism is also applied to the only two cases of subduction of Atlantic tectonic system, the Lesser-Antilles and the South Sandwich subduction systems.
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- Skogseth, R, et al.
(författare)
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Neuropsychiatric correlates of cerebrospinal fluid biomarkers in Alzheimer's disease
- 2008
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Ingår i: Dementia and geriatric cognitive disorders. - : S. Karger AG. - 1421-9824 .- 1420-8008. ; 25:6, s. 559-563
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Tidskriftsartikel (refereegranskat)abstract
- <i>Background:</i> The aim of this study was to explore the relationship between cerebrospinal fluid biomarkers and neuropsychiatric symptoms in people with Alzheimer’s disease. Psychosis, agitation, apathy and depression were assessed using standardised measures in 32 patients with mild Alzheimer’s disease. <i>Methods:</i> The levels of the 42-amino-acid form of β-amyloid (Aβ<sub>1–42</sub>), tau and p-tau (phosphorylated at threonine 181) were quantified using the conventional enzyme-linked immunosorbent assay method. <i>Results:</i> Our result shows that apathy is significantly correlated with tau and p-tau but not with Aβ<sub>1–42</sub>. There were no significant correlations between indices of psychosis/agitation,or depression and cerebrospinal fluid Aβ<sub>1–42</sub>, tau or p-tau concentrations. <i>Conclusion:</i> Our finding suggests that apathy is associated with the level of neurofibrillary tangles in people with mild Alzheimer’s disease. In contrast, the overall levels of neurofibrillary tangles or amyloid plaques do not seem to be associated with depression or psychosis, indicating that other brain changes contribute to these symptoms.
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