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- Abdo, A. A., et al.
(författare)
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DISCOVERY OF HIGH-ENERGY GAMMA-RAY EMISSION FROM THE BINARY SYSTEM PSR B1259-63/LS 2883 AROUND PERIASTRON WITH FERMI
- 2011
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Ingår i: Astrophysical Journal Letters. - 2041-8205. ; 736:1, s. L11-
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Tidskriftsartikel (refereegranskat)abstract
- We report on the discovery of >= 100 MeV gamma-rays from the binary system PSR B1259-63/LS 2883 using the Large Area Telescope (LAT) on board Fermi. The system comprises a radio pulsar in orbit around a Be star. We report on LAT observations from near apastron to similar to 128 days after the time of periastron, t(p), on 2010 December 15. No gamma-ray emission was detected from this source when it was far from periastron. Faint gamma-ray emission appeared as the pulsar approached periastron. At similar to t(p) + 30 days, the >= 100 MeV gamma-ray flux increased over a period of a few days to a peak flux 20-30 times that seen during the pre-periastron period, but with a softer spectrum. For the following month, it was seen to be variable on daily timescales, but remained at similar to(1-4) x 10(-6) cm(-2) s(-1) before starting to fade at similar to t(p) + 57 days. The total gamma-ray luminosity observed during this period is comparable to the spin-down power of the pulsar. Simultaneous radio and X-ray observations of the source showed no corresponding dramatic changes in radio and X-ray flux between the pre-periastron and post-periastron flares. We discuss possible explanations for the observed gamma-ray-only flaring of the source.
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- Grundstrom, M., et al.
(författare)
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Oak pollen seasonality and severity across Europe and modelling the season start using a generalized phenological model
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 663, s. 527-536
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Tidskriftsartikel (refereegranskat)abstract
- Oak pollen seasons are relatively unexplored in large parts of Europe despite producing allergens and being a common tree in both continental and northern parts. Many studies are concentrated only on the Iberian Peninsula. In this study, the seasonal pattern of oak pollen in Europe was analysed using 10 observation sites, ranging from Spain to Sweden. The magnitude of peaks and annual pollen integral together with season-length were studied and substantially higher pollen levels and longer seasons were found in Spain. Two northern sites in Denmark and Sweden showed high oak pollen peaks together with two sites in Spain and United Kingdom. The study also tested four common definitions of season start and applied a generalized phenological model for computing the start of the pollen season. The most accurate definition for a European-wide description of the observed oak pollen start was when the cumulative daily average pollen count reached 50 grains per cubic meter. For the modelling of the start a thermal time method based on Growing Degree Day (GDD) was implemented, utilizing daily temperatures and a generalized approach to identify model parameters applicable to all included sites. GDD values varied between sites and generally followed a decreasing gradient from south to north, with some exceptions. Modelled onsets with base temperatures below 7 degrees C matched well with observed onsets and 76% of the predictions differed <= 4 days compared to observed onsets when using a base temperature of 2 degrees C. Base temperatures above 7 degrees C frequently predicted onsets differing >1 week from the observed. This general approach can be extended to a larger area where pollen observations are non-existent. The presented work will increase the understanding of oak pollen variation in Europe and provide knowledge of its phenology, which is a critical aspect both for modelling purposes on large-scale and assessing the human exposure to oak allergens. (C) 2019 The Authors. Published by Elsevier B.V.
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- Molina, Irene, Professor i kulturgeografi, ssk Bosättning och bebyggelse, 1957-, et al.
(författare)
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City, housing and gender from an inclusive and intersectional perspective
- 2022
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Ingår i: Revista INVI. - : Universidad de Chile. - 0718-1299 .- 0718-8358. ; 37:104, s. 1-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Los trabajos reunidos en esta colección tienen en común la aplicación de perspectivas interseccionales para entender la vida urbana desde los bordes, a través de situaciones observadas en diversos contextos nacionales y regionales, en el espacio público, el acceso a la vivienda, experiencias y estrategias de resistencia espacial, entre otros tópicos relevantes.
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