Institution
University of Iceland
Education•Reykjavik, Suðurnes, Iceland•
About: University of Iceland is a education organization based out in Reykjavik, Suðurnes, Iceland. It is known for research contribution in the topics: Population & Genome-wide association study. The organization has 5423 authors who have published 16199 publications receiving 694762 citations. The organization is also known as: Háskóli Íslands.
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Norwegian Institute for Air Research1, Université libre de Bruxelles2, Michigan Technological University3, University of Cambridge4, Swiss Federal Laboratories for Materials Science and Technology5, German Aerospace Center6, University of Natural Resources and Life Sciences, Vienna7, University of Iceland8
TL;DR: In this article, an inversion scheme was used to estimate the volcanic ash source strength as a function of altitude and time, and the results showed that volcanic ash concentrations at some altitude in the atmosphere exceeded the limits for the "Normal" flying zone in up to 14 % (6-16 %), 2 % (1-3 %) and 7 % (4-11 %) of the European area.
Abstract: . The April–May, 2010 volcanic eruptions of Eyjafjallajokull, Iceland caused significant economic and social disruption in Europe whilst state of the art measurements and ash dispersion forecasts were heavily criticized by the aviation industry. Here we demonstrate for the first time that large improvements can be made in quantitative predictions of the fate of volcanic ash emissions, by using an inversion scheme that couples a priori source information and the output of a Lagrangian dispersion model with satellite data to estimate the volcanic ash source strength as a function of altitude and time. From the inversion, we obtain a total fine ash emission of the eruption of 8.3 ± 4.2 Tg for particles in the size range of 2.8–28 μm diameter. We evaluate the results of our model results with a posteriori ash emissions using independent ground-based, airborne and space-borne measurements both in case studies and statistically. Subsequently, we estimate the area over Europe affected by volcanic ash above certain concentration thresholds relevant for the aviation industry. We find that during three episodes in April and May, volcanic ash concentrations at some altitude in the atmosphere exceeded the limits for the "Normal" flying zone in up to 14 % (6–16 %), 2 % (1–3 %) and 7 % (4–11 %), respectively, of the European area. For a limit of 2 mg m−3 only two episodes with fractions of 1.5 % (0.2–2.8 %) and 0.9 % (0.1–1.6 %) occurred, while the current "No-Fly" zone criterion of 4 mg m−3 was rarely exceeded. Our results have important ramifications for determining air space closures and for real-time quantitative estimations of ash concentrations. Furthermore, the general nature of our method yields better constraints on the distribution and fate of volcanic ash in the Earth system.
346 citations
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National Institutes of Health1, Johns Hopkins University2, University of Vermont3, Erasmus University Rotterdam4, Wellcome Trust Sanger Institute5, King's College London6, Boston University7, University of Washington8, University of Iceland9, University of Greifswald10, Geneva College11, University of Cambridge12, University of Texas Health Science Center at Houston13, Cedars-Sinai Medical Center14, Leiden University15, Leiden University Medical Center16, Harvard University17
TL;DR: This study has identified new determinants of erythrocyte traits, offering insight into common variants underlying variation in ery throatcyte measures, and identifies 23 loci significantly associated with these traits.
Abstract: Measurements of erythrocytes within the blood are important clinical traits and can indicate various hematological disorders. We report here genome-wide association studies (GWAS) for six erythrocyte traits, including hemoglobin concentration (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and red blood cell count (RBC). We performed an initial GWAS in cohorts of the CHARGE Consortium totaling 24,167 individuals of European ancestry and replication in additional independent cohorts of the HaemGen Consortium totaling 9,456 individuals. We identified 23 loci significantly associated with these traits in a meta-analysis of the discovery and replication cohorts (combined P values ranging from 5 x 10(-8) to 7 x 10(-86)). Our findings include loci previously associated with these traits (HBS1L-MYB, HFE, TMPRSS6, TFR2, SPTA1) as well as new associations (EPO, TFRC, SH2B3 and 15 other loci). This study has identified new determinants of erythrocyte traits, offering insight into common variants underlying variation in erythrocyte measures.
346 citations
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TL;DR: Four new genome-wide significant loci near the SOST gene at 17q21, the MARK3 gene at 14q32, the SP7 gene at 12q13 and the TNFRSF11A (RANK) gene at 18q21 are identified and nonsynonymous SNPs in the C17orf53, LRP4, ADAM19 and IBSP genes were suggestively associated with bone density.
Abstract: In an extended genome-wide association study of bone mineral density among 6,865 Icelanders and a follow-up in 8,510 subjects of European descent, we identified four new genome-wide significant loci. These are near the SOST gene at 17q21, the MARK3 gene at 14q32, the SP7 gene at 12q13 and the TNFRSF11A (RANK) gene at 18q21. Furthermore, nonsynonymous SNPs in the C17orf53, LRP4, ADAM19 and IBSP genes were suggestively associated with bone density.
345 citations
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TL;DR: Experimental results on three widely used real HSIs indicate that the proposed SC-MK approach outperforms several well-known classification methods.
Abstract: For the classification of hyperspectral images (HSIs), this paper presents a novel framework to effectively utilize the spectral–spatial information of superpixels via multiple kernels, which is termed as superpixel-based classification via multiple kernels (SC-MK). In the HSI, each superpixel can be regarded as a shape-adaptive region, which consists of a number of spatial neighboring pixels with very similar spectral characteristics. First, the proposed SC-MK method adopts an oversegmentation algorithm to cluster the HSI into many superpixels. Then, three kernels are separately employed for the utilization of the spectral information, as well as spatial information, within and among superpixels. Finally, the three kernels are combined together and incorporated into a support vector machine classifier. Experimental results on three widely used real HSIs indicate that the proposed SC-MK approach outperforms several well-known classification methods.
344 citations
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TL;DR: In this paper, a case study examines methods chosen for the development and implementation of questionnaires used to obtain information on knowledge and perception of volcanic hazards in a tourist region in southern Iceland.
Abstract: . Questionnaires are popular and fundamental tools for acquiring information on public knowledge and perception of natural hazards. Questionnaires can provide valuable information to emergency management agencies for developing risk management procedures. Although many natural hazards researchers describe results generated from questionnaires, few explain the techniques used for their development and implementation. Methodological detail should include, as a minimum, response format (open/closed questions), mode of delivery, sampling technique, response rate and access to the questionnaire to allow reproduction of or comparison with similar studies. This article reviews current knowledge and practice for developing and implementing questionnaires. Key features include questionnaire design, delivery mode, sampling techniques and data analysis. In order to illustrate these aspects, a case study examines methods chosen for the development and implementation of questionnaires used to obtain information on knowledge and perception of volcanic hazards in a tourist region in southern Iceland. Face-to-face interviews highlighted certain issues with respect to question structure and sequence. Recommendations are made to overcome these problems before the questionnaires are applied in future research projects. In conclusion, basic steps that should be disclosed in the literature are provided as a checklist to ensure that reliable, replicable and valid results are produced from questionnaire based hazard knowledge and risk perception research.
343 citations
Authors
Showing all 5561 results
Name | H-index | Papers | Citations |
---|---|---|---|
Albert Hofman | 267 | 2530 | 321405 |
Kari Stefansson | 206 | 794 | 174819 |
Ronald Klein | 194 | 1305 | 149140 |
Eric Boerwinkle | 183 | 1321 | 170971 |
Unnur Thorsteinsdottir | 167 | 444 | 121009 |
Vilmundur Gudnason | 159 | 837 | 123802 |
Hakon Hakonarson | 152 | 968 | 101604 |
Bernhard O. Palsson | 147 | 831 | 85051 |
Andrew T. Hattersley | 146 | 768 | 106949 |
Fernando Rivadeneira | 146 | 628 | 86582 |
Rattan Lal | 140 | 1383 | 87691 |
Jonathan G. Seidman | 137 | 563 | 89782 |
Christine E. Seidman | 134 | 519 | 67895 |
Augustine Kong | 134 | 237 | 89818 |
Timothy M. Frayling | 133 | 500 | 100344 |