| 1. |
- Abdo, A. A., et al.
(författare)
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FERMI/LARGE AREA TELESCOPE DISCOVERY OF GAMMA-RAY EMISSION FROM THE FLAT-SPECTRUM RADIO QUASAR PKS 1454-354
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 697:1, s. 934-941
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope of high-energy gamma-ray (GeV) emission from the flat-spectrum radio quasar PKS 1454-354 (z = 1.424). On 2008 September 4, the source rose to a peak flux of (3.5 +/- 0.7) x 10(-6) ph cm(-2) s(-1) (E > 100 MeV) on a timescale of hours and then slowly dropped over the following 2 days. No significant spectral changes occurred during the flare. Fermi/LAT observations also showed that PKS 1454-354 is the most probable counterpart of the unidentified EGRET source 3EG J1500-3509. Multiwavelength measurements performed during the following days (7 September with Swift; 6-7 September with the ground-based optical telescope Automated Telescope for Optical Monitoring; 13 September with the Australia Telescope Compact Array) resulted in radio, optical, UV, and X-ray fluxes greater than archival data, confirming the activity of PKS 1454-354.
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| 2. |
- Abdo, A. A., et al.
(författare)
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SUZAKU OBSERVATIONS OF LUMINOUS QUASARS : REVEALING THE NATURE OF HIGH-ENERGY BLAZAR EMISSION IN LOW-LEVEL ACTIVITY STATES
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 716:1, s. 835-849
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Tidskriftsartikel (refereegranskat)abstract
- We present the results from the Suzaku X-ray observations of five flat-spectrum radio quasars (FSRQs), namely PKS 0208-512, Q 0827+243, PKS 1127-145, PKS 1510-089, and 3C 454.3. All these sources were additionally monitored simultaneously or quasi-simultaneously by the Fermi satellite in gamma rays and the Swift UVOT in the UV and optical bands, respectively. We constructed their broadband spectra covering the frequency range from 10(14) Hz up to 10(25) Hz, and those reveal the nature of high-energy emission of luminous blazars in their low-activity states. The analyzed X-ray spectra are well fitted by a power-law model with photoelectric absorption. In the case of PKS 0208-512, PKS 1127-145, and 3C 454.3, the X-ray continuum showed indication of hardening at low energies. Moreover, when compared with the previous X-ray observations, we see a significantly increasing contribution of low-energy photons to the total X-ray fluxes when the sources are getting fainter. The same behavior can be noted in the Suzaku data alone. A likely explanation involves a variable, flat-spectrum component produced via inverse-Compton emission, plus an additional, possibly steady soft X-ray component prominent when the source gets fainter. This soft X-ray excess is represented either by a steep power-law (photon indices Gamma similar to 3-5) or a blackbody-type emission with temperatures kT similar to 0.1-0.2 keV. We model the broadband spectra of the five observed FSRQs using synchrotron self-Compton and/or external-Compton radiation models. Our modeling suggests that the difference between the low-and high-activity states in luminous blazars is due to the different total kinetic power of the jet, most likely related to varying bulk Lorentz factor of the outflow within the blazar emission zone.
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| 3. |
- Screaton, E., et al.
(författare)
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Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan : Results from IODP Expedition 316 Sites C0006 and C0007
- 2009
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Ingår i: Geochemistry Geophysics Geosystems. - 1525-2027. ; 10, s. Q0AD01-
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Tidskriftsartikel (refereegranskat)abstract
- Integrated Ocean Drilling Program (IODP) Expedition 316 Sites C0006 and C0007 examined the deformation front of the Nankai accretionary prism offshore the Kii Peninsula, Japan. In the drilling area, the frontal thrust shows unusual behavior as compared to other regions of the Nankai Trough. Drilling results, integrated with observations from seismic reflection profiles, suggest that the frontal thrust has been active since similar to 0.78-0.436 Ma and accommodated similar to 13 to 34% of the estimated plate convergence during that time. The remainder has likely been distributed among out-of-sequence thrusts further landward and/or accommodated through diffuse shortening. Unlike results of previous drilling on the Nankai margin, porosity data provide no indication of undercompaction beneath thrust faults. Furthermore, pore water geochemistry data lack clear indicators of fluid flow from depth. These differences may be related to coarser material with higher permeability or more complex patterns of faulting that could potentially provide more avenues for fluid escape. In turn, fluid pressures may affect deformation. Well-drained, sand-rich material under the frontal thrust could have increased fault strength and helped to maintain a large taper angle near the toe. Recent resumption of normal frontal imbrication is inferred from seismic reflection data. Associated decollement propagation into weaker sediments at depth may help explain evidence for recent slope failures within the frontal thrust region. This evidence consists of seafloor bathymetry, normal faults documented in cores, and low porosities in near surface sediments that suggest removal of overlying material. Overall, results provide insight into the complex interactions between incoming materials, deformation, and fluids in the frontal thrust region.
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| 4. |
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| 5. |
- Adelani, David Ifeoluwa, et al.
(författare)
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MasakhaNER 2.0: Africa-centric Transfer Learning for Named Entity Recognition
- 2022
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Ingår i: Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing. - : Association for Computational Linguistics (ACL). ; , s. 4488-4508
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Konferensbidrag (refereegranskat)abstract
- African languages are spoken by over a billion people, but are underrepresented in NLP research and development. The challenges impeding progress include the limited availability of annotated datasets, as well as a lack of understanding of the settings where current methods are effective. In this paper, we make progress towards solutions for these challenges, focusing on the task of named entity recognition (NER). We create the largest human-annotated NER dataset for 20 African languages, and we study the behavior of state-of-the-art cross-lingual transfer methods in an Africa-centric setting, demonstrating that the choice of source language significantly affects performance. We show that choosing the best transfer language improves zero-shot F1 scores by an average of 14 points across 20 languages compared to using English. Our results highlight the need for benchmark datasets and models that cover typologically-diverse African languages.
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| 6. |
- Adelani, David Ifeoluwa, et al.
(författare)
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MasakhaNER: Named Entity Recognition for African Languages
- 2021
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Ingår i: Transactions of the Association for Computational Linguistics. - : MIT Press. - 2307-387X. ; 9, s. 1116-1131
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Tidskriftsartikel (refereegranskat)abstract
- We take a step towards addressing the under-representation of the African continent in NLP research by bringing together different stakeholders to create the first large, publicly available, high-quality dataset for named entity recognition (NER) in ten African languages. We detail the characteristics of these languages to help researchers and practitioners better understand the challenges they pose for NER tasks. We analyze our datasets and conduct an extensive empirical evaluation of state-of-the-art methods across both supervised and transfer learning settings. Finally, we release the data, code, and models to inspire future research on African NLP.
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| 7. |
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| 8. |
- Mannheimer, C, et al.
(författare)
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The problem of chronic refractory angina
- 2002
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 23:5, s. 355-370
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Tidskriftsartikel (refereegranskat)abstract
- It has been recognized that there is a group of patients with severe disabling angina and coronary artery disease who are refractory to conventional forms of treatment. Although this issue has already been debated at the level of the National Societies, we felt that it was appropriate to also tackle it at the European level. This is particularly important in view of the rapid pace of growth of this problem and the lack of a standardized approach. This has encouraged the development of a variety of treatments that vary considerably in terms of cost-effectiveness and safety and require proper validation procedures. The aim of this paper is to draw attention to the problem and start a process that will lead to improvement and harmonization of the care of patients with refractory angina.
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| 9. |
- Olsson, Martin L, et al.
(författare)
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Heterogeneity of the O alleles at the blood group ABO locus in Amerindians
- 1998
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Ingår i: Vox Sanguinis. - : Wiley. - 1423-0410 .- 0042-9007. ; 74:1, s. 46-50
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND OBJECTIVES: Amerindians are blood group O, but the distribution of the various O alleles is unknown. Their ABO genotypes were compared with samples from other Brazilian ethnic groups. MATERIALS AND METHODS: Genomic DNA was examined by PCR-RFLP analysis, PCR-SSP and direct sequencing. RESULTS: An unusual allele distribution was found, with 91% of the O alleles being O1variant. Almost half of these alleles had an additional novel mutation (G542A), which was also detected in a few other Brazilian and European samples. The O alleles correlated completely with ABO-related haplotypes previously determined by Southern blot. CONCLUSION: The three Amerindian tribes represent a homogeneous (ABO blood group) population, except for the G542A mutation. The presence of this mutation in all other populations examined suggests that it originated before the migration of man into America.
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| 10. |
- Olsson, Martin L, et al.
(författare)
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Molecular analysis of the O alleles at the blood group ABO locus in populations of different ethnic origin reveals novel crossing-over events and point mutations
- 1997
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 234:3, s. 779-782
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Tidskriftsartikel (refereegranskat)abstract
- The blood group ABO genotypes of 138 group O individuals with three different ethnic origins in Brazil were determined, including Whites, Blacks and Amerindians. Several previously undescribed O alleles were found, predominantly in the Black group, in which about a third of the samples did not conform to previously known O allele structures. It has been well documented for the first time that some new alleles can arise from crossing-over events between known alleles in the ABO system. This was made possible by both restriction endonuclease analysis and direct sequencing of exons 3-7 in the ABO gene. The anticipated relatively high frequency of some of these new alleles in certain populations, necessitates great care when interpreting results from existing genotype screening methods.
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