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| 2. |
- Fuzzi, Sandro, et al.
(författare)
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Overview of the Po valley fog experiment 1994 (CHEMDROP)
- 1998
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Ingår i: Contributions to Atmospheric Physics. - 0005-8173. ; 71:1, s. 3-19
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Forskningsöversikt (refereegranskat)abstract
- The paper presents an outline of the CHEMDROP field experiment, carried out in November 1994 at the field station of S. Pietro Capofiume in the Po Valley, Italy. The main objective of the project was to address the issue of the size-dependent chemical composition of fog droplets, by experimentally investigating the following processes, which are expected to affect (or be affected by) the chemical composition of fog droplets as a function of size: a) the connection of the size-dependent chemical composition of CCN to the size-dependent composition of fog droplets; b) the gas/liquid partitioning of the gaseous species NH3, SO2, HCHO, HNO3 in fog; c) the Fe(II)/Fe(III) redox cycle in fog water. Some general results and overall conclusions of the experiment are reported in this paper, while more specific scientific questions are discussed in other companion papers in this issue. CHEMDROP results show that several processes concur in determining the size-dependence of fog droplets chemical composition: nucleation scavenging of pre-existing CCN, fog dynamical evolution and gas/liquid exchange between interstitial air and fog droplets. Chemical transformations in the liquid phase can cause further changes in the chemical composition of the droplets. Only by taking into account the combination of all these processes, is it possible to explain the inhomogeneities in fog droplet chemical composition.
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| 3. |
- Günther, Torsten, et al.
(författare)
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Where in the genome are significant single nucleotide polymorphisms from genome-wide association studies located?
- 2011
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Ingår i: Omics. - : Mary Ann Liebert Inc. - 1536-2310 .- 1557-8100. ; 15:7-8, s. 507-12
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Tidskriftsartikel (refereegranskat)abstract
- Recent technological progress has permitted the efficient performance of genome-wide association studies (GWAS) to map genetic variants associated with common diseases. Here, we analyzed 2,893 single nucleotide polymorphisms (SNPs) that have been identified in 593 published GWAS as associated with a disease phenotype with respect to their genomic location. In absolute numbers, most significant SNPs are located in intergenic regions and introns. When compared to their representation on the chips, there is essentially overrepresentation of nonsynonymous coding SNPs (nsSNPs), synonymous coding SNPs, and SNPs in untranscribed regions upstream of genes among the disease associated SNPs. A Gene Ontology term analysis showed that genes putatively causing a phenotype often code for membrane associated proteins or signal transduction genes.
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| 4. |
- Laj, Paolo, et al.
(författare)
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The size dependent composition of fog droplets
- 1998
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Ingår i: Contributions to Atmospheric Physics. - 0005-8173. ; 71:1, s. 115-130
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Tidskriftsartikel (refereegranskat)abstract
- The size dependency of fog droplet concentration and composition was studied using newly developed droplet impactors during the CHEMDROP campaign in the Po Valley (Italy). A strong size dependency of solute concentrations was measured during several fog episodes. The ionic strength of the droplet solutions varies as a function of droplet diameter, showing maximum values in the 9-19 μm diameter range. The solute concentration varies up to a factor of 10 among droplets of different diameter. Similarly, differences of up to 2 pH units are found among droplets of different diameter. The solute dependency of aerosol and droplets species from 0.1 μm to 50 μm is investigated. The monomodal behaviour of the solute concentration in droplets can be explained by both diffusional condensation of the aerosols serving as cloud condensation nuclei (CCN) and the air/liquid transfer of volatile species, in particular for HNO3 and NH3. The distribution of sulphur species is also size-dependent and is directly linked to the pH variations across the droplet spectrum, resulting in HMSA formation in small droplets and S(IV) oxidation large droplets.
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| 5. |
- Leutritz, Tobias, et al.
(författare)
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Multi-parameter mapping (MPM) of relaxation (R1, R2*), proton density (PD) and magnetization transfer saturation (MT) at 3T: a multi-center dual-vendor reproducibility and repeatability study
- 2020
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Ingår i: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 41:15, s. 4232-4247
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Tidskriftsartikel (refereegranskat)abstract
- Multicenter clinical and quantitative magnetic resonance imaging (qMRI) studies require a high degree of reproducibility across different sites and scanner manufacturers, as well as time points. We therefore implemented a multiparameter mapping (MPM) protocol based on vendor's product sequences and demonstrate its repeatability and reproducibility for whole‐brain coverage. Within ~20 min, four MPM metrics (magnetization transfer saturation [MT], proton density [PD], longitudinal [R1], and effective transverse [R2*] relaxation rates) were measured using an optimized 1 mm isotropic resolution protocol on six 3 T MRI scanners from two different vendors. The same five healthy participants underwent two scanning sessions, on the same scanner, at each site. MPM metrics were calculated using the hMRI‐toolbox. To account for different MT pulses used by each vendor, we linearly scaled the MT values to harmonize them across vendors. To determine longitudinal repeatability and inter‐site comparability, the intra‐site (i.e., scan‐rescan experiment) coefficient of variation (CoV), inter‐site CoV, and bias across sites were estimated. For MT, R1, and PD, the intra‐ and inter‐site CoV was between 4 and 10% across sites and scan time points for intracranial gray and white matter. A higher intra‐site CoV (16%) was observed in R2* maps. The inter‐site bias was below 5% for all parameters. In conclusion, the MPM protocol yielded reliable quantitative maps at high resolution with a short acquisition time. The high reproducibility of MPM metrics across sites and scan time points combined with its tissue microstructure sensitivity facilitates longitudinal multicenter imaging studies targeting microstructural changes, for example, as a quantitative MRI biomarker for interventional clinical trials.
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