| 1. |
- Dimov, Stefan S., et al.
(författare)
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4M Network of Excellence, Progress report 2009
- 2009
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Ingår i: 4M/ICOMM 2009. ; , s. s.1-9
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Konferensbidrag (refereegranskat)abstract
- This paper gives a brief overview of the activities of the 4M Network of Excellence during the last nine months of its funded period. The 4M Divisions summarise their activity and outline their plans to continue to working together in future. Finally a summary of achievements during the whole lifetime of the Network is given
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| 2. |
- Haustein, K., et al.
(författare)
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Atmospheric dust modeling from meso to global scales with the online NMMB/BSC-Dust model - Part 2 : Experimental campaigns in Northern Africa
- 2012
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:6, s. 2933-2958
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Tidskriftsartikel (refereegranskat)abstract
- The new NMMB/BSC-Dust model is intended to provide short to medium-range weather and dust forecasts from regional to global scales. It is an online model in which the dust aerosol dynamics and physics are solved at each model time step. The companion paper (P,rez et al., 2011) develops the dust model parameterizations and provides daily to annual evaluations of the model for its global and regional configurations. Modeled aerosol optical depth (AOD) was evaluated against AERONET Sun photometers over Northern Africa, Middle East and Europe with correlations around 0.6-0.7 on average without dust data assimilation. In this paper we analyze in detail the behavior of the model using data from the Saharan Mineral dUst experiment (SAMUM-1) in 2006 and the Bod,l, Dust Experiment (BoDEx) in 2005. AOD from satellites and Sun photometers, vertically resolved extinction coefficients from lidars and particle size distributions at the ground and in the troposphere are used, complemented by wind profile data and surface meteorological measurements. All simulations were performed at the regional scale for the Northern African domain at the expected operational horizontal resolution of 25 km. Model results for SAMUM-1 generally show good agreement with satellite data over the most active Saharan dust sources. The model reproduces the AOD from Sun photometers close to sources and after long-range transport, and the dust size spectra at different height levels. At this resolution, the model is not able to reproduce a large haboob that occurred during the campaign. Some deficiencies are found concerning the vertical dust distribution related to the representation of the mixing height in the atmospheric part of the model. For the BoDEx episode, we found the diurnal temperature cycle to be strongly dependant on the soil moisture, which is underestimated in the NCEP analysis used for model initialization. The low level jet (LLJ) and the dust AOD over the Bod,l, are well reproduced. The remaining negative AOD bias (due to underestimated surface wind speeds) can be substantially reduced by decreasing the threshold friction velocity in the model.
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| 3. |
- Mueller, D., et al.
(författare)
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Comparison of optical and microphysical properties of pure Saharan mineral dust observed with AERONET Sun photometer, Raman lidar, and in situ instruments during SAMUM 2006
- 2012
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 117, s. D07211-
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Tidskriftsartikel (refereegranskat)abstract
- The Saharan Mineral Dust Experiment (SAMUM) 2006, Morocco, aimed at the characterization of optical, physical, and radiative properties of Saharan dust. AERONET Sun photometer, several lidars (Raman and high-spectral-resolution instruments), and airborne and ground-based in situ instruments provided us with a comprehensive set of data on particle-shape dependent and particle-shape independent dust properties. We compare 4 measurement days in detail, and we carry out a statistical analysis for some of the inferred data products for the complete measurement period. Particle size distributions and complex refractive indices inferred from the Sun photometer observations and measured in situ aboard a research aircraft show systematic differences. We find differences in the wavelength-dependence of single-scattering albedo, compared to light-scattering computations that use data from SOAP (spectral optical absorption photometer). AERONET data products of particle size distribution, complex refractive index, and axis ratios were used to compute particle extinction-to-backscatter (lidar) ratios and linear particle depolarization ratios. We find differences for these parameters to lidar measurements of lidar ratio and particle depolarization ratio. Differences particularly exist at 355 nm, which may be the result of differences of the wavelength-dependent complex refractive index that is inferred by the methods employed in this field campaign. We discuss various error sources that may lead to the observed differences.
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| 4. |
- Willem, Michael, et al.
(författare)
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eta-Secretase processing of APP inhibits neuronal activity in the hippocampus
- 2015
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 526:7573, s. 443-447
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer disease (AD) is characterized by the accumulation of amyloid plaques, which are predominantly composed of amyloid-beta peptide(1). Two principal physiological pathways either prevent or promote amyloid-beta generation from its precursor, beta-amyloid precursor protein (APP), in a competitive manne(r)1. Although APP processing has been studied in great detail, unknown proteolytic events seem to hinder stoichiometric analyses of APP metabolism in vivo(2). Here we describe a new physiological APP processing pathway, which generates proteolytic fragments capable of inhibiting neuronal activity within the hippocampus. We identify higher molecular mass carboxy-terminal fragments (CTFs) of APP, termed CTF-eta, in addition to the long-known CTF-alpha and CTF-beta fragments generated by the alpha- and beta-secretases ADAM10 (a disintegrin and metalloproteinase 10) and BACE1 (beta-site APP cleaving enzyme 1), respectively. CTF-eta generation is mediated in part by membrane-bound matrix metalloproteinases such as MT5-MMP, referred to as g-secretase activity. g-Secretase cleavage occurs primarily at amino acids 504-505 of APP(695), releasing a truncated ectodomain. After shedding of this ectodomain, CTF-eta is further processed by ADAM10 and BACE1 to release long and short A eta peptides (termed A eta-alpha and A eta-beta). CTFs produced by g-secretase are enriched in dystrophic neurites in an AD mouse model and in human AD brains. Genetic and pharmacological inhibition of BACE1 activity results in robust accumulation of CTF-eta and A eta-alpha. In mice treated with a potent BACE1 inhibitor, hippocampal long-term potentiation was reduced. Notably, when recombinant or synthetic A eta-alpha was applied on hippocampal slices ex vivo, long-term potentiation was lowered. Furthermore, in vivo single-cell two-photon calcium imaging showed that hippocampal neuronal activity was attenuated by A eta-alpha. These findings not only demonstrate a major functionally relevant APP processing pathway, but may also indicate potential translational relevance for therapeutic strategies targeting APP processing.
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