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Institution

University of Iceland

EducationReykjavik, 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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Journal ArticleDOI
TL;DR: In this paper, a structural hypothesis is proposed where each continuous human interaction is seen as the performance of a set of a particular type of temporal patterns, and a computerized detection method and illustrative empirical findings from various types of face-to-face interactions in children and adults are presented.
Abstract: It is widely believed that human interaction is much more regular than has yet been detected. What kinds of hidden regularities exist is, however, unsettled. In this paper a structural hypothesis is proposed where each continuous human interaction is seen as the performance of a set of a particular type of temporal patterns. Some of these repeated intra- and inter-individual real-time behavior patterns may be mutually exclusive in time while others may overlap in various ways. Perceptual limitations making such patterns hidden to the naked eye are illustrated. A computerized detection method and illustrative empirical findings from various types of face-to-face interactions in children and adults are presented. The specially developed pattern detection and analysis software, THEME, is also shortly described.

194 citations

Journal ArticleDOI
TL;DR: There is a need for guidelines outlining the minimum requirements to justify professional and ethical use of unstandardised psychological instruments in applied settings and eight criteria are suggested are suggested.
Abstract: Translated but unstandardised psychological instruments are widely used in non-English speaking countries. For many of these instruments meagre information is available on the method of translation, extent of adaptations, reliability, validity and other psychometric properties. This lack of information has unforeseen consequences for test-takers and decision making in clinical and other applied settings. In this paper it is argued that there is a need for guidelines outlining the minimum requirements to justify professional and ethical use of unstandardised psychological instruments. Eight criteria are suggested and all of these should be met in order to justify the use of unstandardised instruments in applied settings. Finally, it is emphasised that the use of unstandardised instruments should be viewed as temporary and tentative; the final aim of all translations and adaptations of psychological instruments that are to be used in a clinical or other applied context should be proper standardisation.

193 citations

Journal ArticleDOI
TL;DR: Previous associations found in white populations were replicated and new associations were identified in Asian populations, and the associations between the 5p15 variants and lung cancer differed by histology; odds ratios for rs2736100 were highest in adenocarcinoma and for rs402710 were highest for squamous cell carcinomas.
Abstract: BACKGROUND: Genome-wide association studies have identified three chromosomal regions at 15q25, 5p15, and 6p21 as being associated with the risk of lung cancer. To confirm these associations in independent studies and investigate heterogeneity of these associations within specific subgroups, we conducted a coordinated genotyping study within the International Lung Cancer Consortium based on independent studies that were not included in previous genome-wide association studies. METHODS: Genotype data for single-nucleotide polymorphisms at chromosomes 15q25 (rs16969968, rs8034191), 5p15 (rs2736100, rs402710), and 6p21 (rs2256543, rs4324798) from 21 case-control studies for 11 645 lung cancer case patients and 14 954 control subjects, of whom 85% were white and 15% were Asian, were pooled. Associations between the variants and the risk of lung cancer were estimated by logistic regression models. All statistical tests were two-sided. RESULTS: Associations between 15q25 and the risk of lung cancer were replicated in white ever-smokers (rs16969968: odds ratio [OR] = 1.26, 95% confidence interval [CI] = 1.21 to 1.32, P(trend) = 2 x 10(-26)), and this association was stronger for those diagnosed at younger ages. There was no association in never-smokers or in Asians between either of the 15q25 variants and the risk of lung cancer. For the chromosome 5p15 region, we confirmed statistically significant associations in whites for both rs2736100 (OR = 1.15, 95% CI = 1.10 to 1.20, P(trend) = 1 x 10(-10)) and rs402710 (OR = 1.14, 95% CI = 1.09 to 1.19, P(trend) = 5 x 10(-8)) and identified similar associations in Asians (rs2736100: OR = 1.23, 95% CI = 1.12 to 1.35, P(trend) = 2 x 10(-5); rs402710: OR = 1.15, 95% CI = 1.04 to 1.27, P(trend) = .007). The associations between the 5p15 variants and lung cancer differed by histology; odds ratios for rs2736100 were highest in adenocarcinoma and for rs402710 were highest in adenocarcinoma and squamous cell carcinomas. This pattern was observed in both ethnic groups. Neither of the two variants on chromosome 6p21 was associated with the risk of lung cancer. CONCLUSIONS: In this international genetic association study of lung cancer, previous associations found in white populations were replicated and new associations were identified in Asian populations. Future genetic studies of lung cancer should include detailed stratification by histology.

193 citations

Journal ArticleDOI
Markus Ackermann, Marco Ajello1, Andrea Albert2, W. B. Atwood3  +157 moreInstitutions (34)
TL;DR: This work measures, for the first time, the source count distribution, dN/dS, of extragalactic γ-ray sources at E>50 GeV and finds that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL.
Abstract: The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, dN/dS, of extragalactic γ-ray sources at E>50 GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (∼8×10^{-12} ph cm^{-2} s^{-1}). We employ a one-point photon fluctuation analysis to constrain the behavior of dN/dS below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, S_{b}, in the range [8×10^{-12},1.5×10^{-11}] ph cm^{-2} s^{-1} and power-law indices below and above the break of α_{2}∈[1.60,1.75] and α_{1}=2.49±0.12, respectively. Integration of dN/dS shows that point sources account for at least 86_{-14}^{+16}% of the total extragalactic γ-ray background. The simple form of the derived source count distribution is consistent with a single population (i.e., blazars) dominating the source counts to the minimum flux explored by this analysis. We estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.

193 citations

Journal ArticleDOI
TL;DR: In this article, the authors present high-resolution spectroscopic observations of GRB 060418, obtained with VLT/UVES, with a resolving power of 7 km s-1, and a signal-to-noise ratio of 10-15.490.
Abstract: We present high-resolution spectroscopic observations of GRB 060418, obtained with VLT/UVES. These observations were triggered using the VLT Rapid-Response Mode (RRM), which allows for automated observations of transient phenomena, without any human intervention. This resulted in the first UVES exposure of GRB 060418 to be started only 10 min after the initial Swift satellite trigger. A sequence of spectra covering 330-670 nm were acquired at 11, 16, 25, 41 and 71 minutes (mid-exposure) after the trigger, with a resolving power of 7 km s-1, and a signal-to-noise ratio of 10-15. This time-series clearly shows evidence for time variability of allowed transitions involving Fe II fine-structure levels (^6D{7/2}, ^6D{5/2}, ^6D{3/2}, and ^6D{1/2}), and metastable levels of both Fe II (^4F{9/2} and ^4D{7/2}) and Ni II (^4F{9/2}), at the host-galaxy redshift z=1.490. This is the first report of absorption lines arising from metastable levels of Fe II and Ni II along any GRB sightline. We model the observed evolution of the level populations with three different excitation mechanisms: collisions, excitation by infra-red photons, and fluorescence following excitation by ultraviolet photons. Our data allow us to reject the collisional and IR excitation scenarios with high confidence. The UV pumping model, in which the GRB afterglow UV photons excite a cloud of atoms with a column density N, distance d, and Doppler broadening parameter b, provides an excellent fit, with best-fit values: log N(Fe II) = 14.75+0.06-0.04, log N(Ni II)=13.84±0.02, d=1.7±0.2 kpc, and b=25±3 km s-1. The success of our UV pumping modeling implies that no significant amount of Fe II or Ni II is present at distances smaller than 1.7 kpc, most likely because it is ionized by the GRB X-ray/UV flash. Because neutral hydrogen is more easily ionized than Fe II and Ni II, this minimum distance also applies to any H I present. Therefore the majority of very large H I column densities typically observed along GRB sightlines may not be located in the immediate environment of the GRB. The UV pumping fit also constrains two GRB afterglow parameters: the spectral slope, beta = -0.5+0.8-1.0, and the total rest-frame UV flux that irradiated the cloud since the GRB trigger, constraining the magnitude of a possible UV flash. Based on observations collected at the European Southern Observatory, Chile; proposal no. 77.D-0661.

192 citations


Authors

Showing all 5561 results

NameH-indexPapersCitations
Albert Hofman2672530321405
Kari Stefansson206794174819
Ronald Klein1941305149140
Eric Boerwinkle1831321170971
Unnur Thorsteinsdottir167444121009
Vilmundur Gudnason159837123802
Hakon Hakonarson152968101604
Bernhard O. Palsson14783185051
Andrew T. Hattersley146768106949
Fernando Rivadeneira14662886582
Rattan Lal140138387691
Jonathan G. Seidman13756389782
Christine E. Seidman13451967895
Augustine Kong13423789818
Timothy M. Frayling133500100344
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202377
2022209
20211,222
20201,118
20191,140
20181,070