| 1. |
- Acciari, V. A., et al.
(författare)
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Radio Imaging of the Very-High-Energy gamma-Ray Emission Region in the Central Engine of a Radio Galaxy
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 325:5939, s. 444-448
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Tidskriftsartikel (refereegranskat)abstract
- The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.
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| 2. |
- Abdo, A. A., et al.
(författare)
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Fermi Large Area Telescope Gamma-Ray Detection of the Radio Galaxy M87
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 707:1, s. 55-60
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Tidskriftsartikel (refereegranskat)abstract
- We report the Fermi Large Area Telescope (LAT) discovery of high-energy (MeV/GeV) γ-ray emission positionally consistent with the center of the radio galaxy M87, at a source significance of over 10σ in 10 months of all-sky survey data. Following the detections of Cen A and Per A, this makes M87 the third radio galaxy seen with the LAT. The faint point-like γ-ray source has a >100 MeV flux of 2.45 (±0.63) × 10–8 photons cm–2 s–1 (photon index = 2.26 ± 0.13) with no significant variability detected within the LAT observation. This flux is comparable with the previous EGRET upper limit (<2.18 × 10–8 photons cm–2 s–1, 2σ), thus there is no evidence for a significant MeV/GeV flare on decade timescales. Contemporaneous Chandra and Very Long Baseline Array data indicate low activity in the unresolved X-ray and radio core relative to previous observations, suggesting M87 is in a quiescent overall level over the first year of Fermi-LAT observations. The LAT γ-ray spectrum is modeled as synchrotron self-Compton (SSC) emission from the electron population producing the radio-to-X-ray emission in the core. The resultant SSC spectrum extrapolates smoothly from the LAT band to the historical-minimum TeV emission. Alternative models for the core and possible contributions from the kiloparsec-scale jet in M87 are considered, and cannot be excluded.
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| 3. |
- Hibbett, D. S., et al.
(författare)
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A higher-level phylogenetic classification of the Fungi
- 2007
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Ingår i: Mycological Research. - : Elsevier BV. - 0953-7562 .- 1469-8102. ; 111, s. 509-547
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive phylogenetic classification of the kingdom Fungi is proposed, with reference to recent molecular phylogenetic analyses, and with input from diverse members of the fungal taxonomic community. The classification includes 195 taxa, down to the level of order, of which 16 are described or validated here: Dikarya subkingdom nov.; Chytridiomycota, Neocallimastigomycota phyla nov.; Monoblepharidomycetes, Neocallimastigomycetes class. nov.; Eurotiomycetidae, Lecarioromycetidae, Mycocaliciomycetidae subclass. nov.; Acarosporales, Corticiales, Baeomycetales, Candelariales, Gloeophyllales, Melanosporales, Trechisporales, Umbilicariales ords. nov. The clade containing Ascomycota and Basidiomycota is classified as subkingdom Dikarya, reflecting the putative synapomorphy of dikaryotic hyphae. The most dramatic shifts in the classification relative to previous works concern the groups that have traditionally been included in the Chytridiomycota and Zygomycota. The Chytridiomycota is retained in a restricted sense, with Blastocladiomycota and Neocallimastigomycota representing segregate phyla of flagellated Fungi. Taxa traditionally placed in Zygomycota are distributed among Glomeromycota and several subphyla incertae sedis, including Mucoromycotina, Entomophthoromycotina, Kickxellomycotina, and Zoopagomycotiria. Microsporidia are included in the Fungi, but no further subdivision of the group is proposed. Several genera of 'basal' Fungi of uncertain position are not placed in any higher taxa, including Basidiobolus, Caulochytrium, Olpidium, and Rozella. (c) 2007 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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| 4. |
- Ballantyne, C., et al.
(författare)
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Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA(2) and cardiovascular diseases
- 2007
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Ingår i: European Journal of Cardiovascular Prevention & Rehabilitation. - 1741-8275. ; 14:1, s. 41344-41344
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Forskningsöversikt (refereegranskat)abstract
- Background A large number of observational epidemiological studies have reported generally positive associations' between circulating mass and activity levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA(2) markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors. Objectives By combination of data from individual participants from all relevant observational studies in a systematic,meta-analysis, with correction for regression dilution (using available data on serial measurements of Lp-PLA(2)), the Lp-PLA(2) Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA(2) with coronary heart disease (and, where data are sufficient with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA(2) and cardiovascular outcomes. Methods A central database is being established containing data on circulating Lp-PLA(2) values, sex and other potential confounding factors, age at baseline Lp-PLA(2) Measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA(2) will yield information on a total of about 15 000 cardiovascular disease endpoints.
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| 5. |
- Ballantyne, C., et al.
(författare)
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Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA2 and cardiovascular diseases
- 2007
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Ingår i: European Journal of Cardiovascular Prevention & Rehabilitation. - : Oxford University Press (OUP). - 1741-8267 .- 1741-8275 .- 2047-4873. ; 14:1, s. 3-11
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Forskningsöversikt (refereegranskat)abstract
- BACKGROUND: A large number of observational epidemiological studies have reported generally positive associations between circulating mass and activity levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA2 markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors. OBJECTIVES: By combination of data from individual participants from all relevant observational studies in a systematic 'meta-analysis', with correction for regression dilution (using available data on serial measurements of Lp-PLA2), the Lp-PLA2 Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA2 with coronary heart disease (and, where data are sufficient, with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA2 and cardiovascular outcomes. METHODS: A central database is being established containing data on circulating Lp-PLA2 values, sex and other potential confounding factors, age at baseline Lp-PLA2 measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA2 will yield information on a total of about 15 000 cardiovascular disease endpoints.
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| 6. |
- Page, R. D., et al.
(författare)
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alpha decay of Re-159 and proton emission from Ta-155
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:6, s. 061302-
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Tidskriftsartikel (refereegranskat)abstract
- The alpha decay of Re-159 has been observed for the first time in reactions of 300 MeV Ni-58 ions with an isotopically enriched Cd-106 target. The Re-159 ions were separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The alpha decay emanates from the proton-emitting pi h(11/2) state in Re-159 with an energy of E-alpha=6776 +/- 26 keV and a branching ratio of 7.5 +/- 3.5%. This alpha decay populates a state in the closed neutron shell nucleus Ta-155, which decays by emitting 1444 +/- 15 keV protons with a half-life of 2.9(-1.1)(+1.5) ms. These values are consistent with the emission of the proton from a pi h(11/2) orbital. These results fit in with the systematics of proton and alpha-particle separation energies in the region, but disagree with the previously reported decay properties of Ta-155.
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| 7. |
- Page, R. D., et al.
(författare)
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Probing single-particle structures beyond the proton drip line
- 2007
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Ingår i: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 137-142
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Konferensbidrag (refereegranskat)abstract
- Single-particle energies have been investigated in the closed neutron shell proton emitter 155Ta. The 155Ta nuclei were populated through the α decay of 159Re, which has been observed for the first time. The 159Re nuclei were produced in reactions of 300 MeV 58Ni ions with an isotopically enriched 106Cd target, separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The 159Re α decay emanates from the proton-emitting πh11/2 state and populates a state in 155Ta which decays by the emission of a proton from a πh 11/2 orbital. The results fit in with the systematics of proton and α-particle separation energies in the region, but disagree with the previously reported decay properties of 155Ta.
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| 8. |
- Joss, D. T., et al.
(författare)
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Discovery of the proton emitting nucleus 159Re
- 2007
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Ingår i: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 28-33
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Konferensbidrag (refereegranskat)abstract
- The observation of the new nuclide 159Re provides important insights into the evolution of single-particle structure in heavy nuclei beyond the proton drip line. The nuclide 159Re was synthesised in the reaction 106Cd(58Ni, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (Ep = 1805±20 keV) and decay half-life (t1/2 = 21±4 μs) with values calculated using the WKB method indicate that the proton is emitted from an h11/2 state. The implications of these results for future experimental investigations into even more proton unbound Re isotopes using in-flight separation techniques are considered.
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| 9. |
- Joss, D. T., et al.
(författare)
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Probing the limit of nuclear existence : Proton emission from Re-159
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 641:1, s. 34-37
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Tidskriftsartikel (refereegranskat)abstract
- The observation of the new nuclide Re-159(75)84 provides important insights into the evolution of single-particle structure and the mass surface in heavy nuclei beyond the proton drip line. This nuclide, 26 neutrons away from the nearest stable rhenium isotope, was synthesised in the reaction Cd-106(Ni-58, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (E-p = 1805 +/- 20 keV) and decay half-life (t(1/2) = 21 +/- 4 mu s) with values calculated using the WKB method indicate that the proton is emitted from an h(11/2) state. The implications of these results for future experimental investigations into even more proton unbound nuclei using in-flight separation techniques are considered.
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| 10. |
- Bishop, D. Timothy, et al.
(författare)
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Genome-wide association study identifies three loci associated with melanoma risk
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:8, s. 920-925
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Tidskriftsartikel (refereegranskat)abstract
- We report a genome-wide association study of melanoma conducted by the GenoMEL consortium based on 317K tagging SNPs for 1,650 selected cases and 4,336 controls, with replication in an additional two cohorts (1,149 selected cases and 964 controls from GenoMEL, and a population-based case-control study in Leeds of 1,163 cases and 903 controls). The genome-wide screen identified five loci with genotyped or imputed SNPs reaching P < 5 x 10(-7). Three of these loci were replicated: 16q24 encompassing MC1R (combined P = 2.54 x 10(-27) for rs258322), 11q14-q21 encompassing TYR (P = 2.41 x 10(-14) for rs1393350) and 9p21 adjacent to MTAP and flanking CDKN2A (P = 4.03 x 10(-7) for rs7023329). MC1R and TYR are associated with pigmentation, freckling and cutaneous sun sensitivity, well-recognized melanoma risk factors. Common variants within the 9p21 locus have not previously been associated with melanoma. Despite wide variation in allele frequency, these genetic variants show notable homogeneity of effect across populations of European ancestry living at different latitudes and show independent association to disease risk.
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