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- Charette, M, et al.
(författare)
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Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES
- 2016
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Ingår i: Philosopical Transactions of the Royal Society A. - : The Royal Society. - 1364-503X. ; 374:2081
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Forskningsöversikt (refereegranskat)abstract
- Continental shelves and shelf seas play a central role in the global carbon cycle. However,their importance with respect to trace element and isotope (TEI) inputs to ocean basinsis less well understood. Here, we present major findings on shelf TEI biogeochemistryfrom the GEOTRACES programme as well as a proof of concept for a new method toestimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEIcycling in the Arctic, transformations within a major river estuary (Amazon), shelf sedimentmicronutrient fluxes and basin-scale estimates of submarine groundwater discharge. Theproposed shelf flux tracer is 228-radium (T1/2 =5.75 yr), which is continuously supplied tothe shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf228Ra fluxes are combined with TEI/ 228Ra ratios to quantify ocean TEI fluxes from thewestern North Atlantic margin. The results from this new approach agree well with previousestimates for shelf Co, Fe, Mn and Zn inputs and exceed published estimates of atmosphericdeposition by factors of approximately 3–23. Lastly, recommendations are made for additionalGEOTRACES process studies and coastal margin-focused section cruises that will help refinethe model and provide better insight on the mechanisms driving shelf-derived TEI fluxesto the ocean.This article is part of the themed issue ‘Biological and climatic impacts of ocean trace elementchemistry’.
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| 2. |
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| 3. |
- Orellana, C, et al.
(författare)
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Measuring Global Brain Atrophy with the Brain Volume/Cerebrospinal Fluid Index: Normative Values, Cut-Offs and Clinical Associations
- 2016
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Ingår i: Neuro-degenerative diseases. - : S. Karger AG. - 1660-2862 .- 1660-2854. ; 16:1-2, s. 77-86
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Tidskriftsartikel (refereegranskat)abstract
- <b><i>Background:</i></b> Global brain atrophy is present in normal aging and different neurodegenerative disorders such as Alzheimer's disease (AD) and is becoming widely used to monitor disease progression. <b><i>Summary:</i></b> The brain volume/cerebrospinal fluid index (BV/CSF index) is validated in this study as a measurement of global brain atrophy. We tested the ability of the BV/CSF index to detect global brain atrophy, investigated the influence of confounders, provided normative values and cut-offs for mild, moderate and severe brain atrophy, and studied associations with different outcome variables. A total of 1,009 individuals were included [324 healthy controls, 408 patients with mild cognitive impairment (MCI) and 277 patients with AD]. Magnetic resonance images were segmented using FreeSurfer, and the BV/CSF index was calculated and studied both cross-sectionally and longitudinally (1-year follow-up). Both AD patients and MCI patients who progressed to AD showed greater global brain atrophy compared to stable MCI patients and controls. Atrophy was associated with older age, larger intracranial volume, less education and presence of the ApoE ε4 allele. Significant correlations were found with clinical variables, CSF biomarkers and several cognitive tests. <b><i>Key Messages:</i></b> The BV/CSF index may be useful for staging individuals according to the degree of global brain atrophy, and for monitoring disease progression. It also shows potential for predicting clinical changes and for being used in the clinical routine.
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