| 41. |
- Larsson, Josefin, et al.
(författare)
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The Matter Beyond the Ring : The Recent Evolution of SN 1987A Observed by the Hubble Space Telescope
- 2019
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Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 886:2
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Tidskriftsartikel (refereegranskat)abstract
- The nearby SN 1987A offers a spatially resolved view of the evolution of a young supernova (SN) remnant. Here we present recent Hubble Space Telescope imaging observations of SN 1987A, which we use to study the evolution of the ejecta, the circumstellar equatorial ring (ER), and the increasing emission from material outside the ER. We find that the inner ejecta have been brightening at a gradually slower rate and that the western side has been brighter than the eastern side since similar to 7000 days. This is expected given that the X-rays from the ER are most likely powering the ejecta emission. At the same time, the optical emission from the ER continues to fade linearly with time. The ER is expanding at 680 50 km s(-1), which reflects the typical velocity of transmitted shocks in the dense hot spots. A dozen spots and a rim of diffuse H alpha emission have appeared outside the ER since 9500 days. The new spots are more than an order of magnitude fainter than the spots in the ER and also fade faster. We show that the spots and diffuse emission outside the ER may be explained by fast ejecta interacting with high-latitude material that extends from the ER toward the outer rings. Further observations of this emission will make it possible to determine the detailed geometry of the high-latitude material and provide insight into the formation of the rings and the mass-loss history of the progenitor.
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| 42. |
- Larsson, Josefin, et al.
(författare)
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THREE-DIMENSIONAL DISTRIBUTION OF EJECTA IN SUPERNOVA 1987A AT 10,000 DAYS
- 2016
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 833:2
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Tidskriftsartikel (refereegranskat)abstract
- Due to its proximity, SN. 1987A offers a unique opportunity to directly observe the geometry of a stellar explosion as it unfolds. Here we present spectral and imaging observations of SN. 1987A obtained similar to 10,000 days after the explosion with HST/STIS and VLT/SINFONI at optical and near-infrared wavelengths. These observations allow us to produce the most detailed 3D map of Ha to date, the first 3D maps for [Ca II] lambda lambda 7292, 7324, [O I] lambda lambda 6300, 6364, and Mg. II lambda lambda 9218, 9244, as well as new maps for [Si I]+[Fe II] 1.644 mu m and He I 2.058 mu m. A comparison with previous observations shows that the [Si I]+[Fe II] flux and morphology have not changed significantly during the past ten years, providing evidence that this line is powered by Ti-44. The time evolution of Ha shows that it is predominantly powered by X-rays from the ring, in agreement with previous findings. All lines that have sufficient signal show a similar large-scale 3D structure, with a north-south asymmetry that resembles a broken dipole. This structure correlates with early observations of asymmetries, showing that there is a global asymmetry that extends from the inner core to the outer envelope. On smaller scales, the two brightest lines, Ha and [Si I]+[Fe II] 1.644 mu m, show substructures at the level of similar to 200-1000 km s(-1) and clear differences in their 3D geometries. We discuss these results in the context of explosion models and the properties of dust in the ejecta.
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| 43. |
- Lee, Kai-Yan, et al.
(författare)
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Efficient photoheating algorithms in time-dependent photoionization simulations
- 2016
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 455:4, s. 4406-4425
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Tidskriftsartikel (refereegranskat)abstract
- We present an extension to the time-dependent photoionization code C-2-RAY to calculate photoheating in an efficient and accurate way. In C-2-RAY, the thermal calculation demands relatively small time-steps for accurate results. We describe two novel methods to reduce the computational cost associated with small time-steps, namely, an adaptive time-step algorithm and an asynchronous evolution approach. The adaptive time-step algorithm determines an optimal time-step for the next computational step. It uses a fast ray-tracing scheme to quickly locate the relevant cells for this determination and only use these cells for the calculation of the time-step. Asynchronous evolution allows different cells to evolve with different time-steps. The asynchronized clocks of the cells are synchronized at the times where outputs are produced. By only evolving cells which may require short time-steps with these short time-steps instead of imposing them to the whole grid, the computational cost of the calculation can be substantially reduced. We show that our methods work well for several cosmologically relevant test problems and validate our results by comparing to the results of another time-dependent photoionization code.
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| 44. |
- Lindahl, Cecilia, et al.
(författare)
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The effect of stress, attitudes and behavior on safety during animal handling in Swedish dairy farming
- 2015
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Ingår i: Journal of Agricultural Safety and Health. - : American Society of Agricultural and Biological Engineers (ASABE). - 1074-7583 .- 1943-7846. ; 21:1, s. 13-34
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Tidskriftsartikel (refereegranskat)abstract
- Working with livestock is a hazardous activity, and animals have been found to be the most frequent injury source on dairy farms. Understanding the risk factors for injury and the causal relationships related to injuries and animal handling is important for developing prevention strategies and effective safety interventions. This study examined stress and handler attitude as possible risk factors for animal handling injuries in dairy farming, in particular when moving cows. Twelve dairy farms were visited on two occasions representing different stress levels: when cows were being moved to milking (low stress) and to hoof trimming (high stress). Behavioral observations of handlers and cows were performed, and questionnaires were completed on attitudes (risk acceptance, safety locus of control, and attitudes toward cows) and stress (perceived stress/energy level and job strain). The injury risks were found to be higher when moving cows to hoof trimming compared with moving cows to milking and gentle, moderately forceful, and forceful interactions were more frequently used. When moving cows to milking, observed risk situations were related only to the perceived energy level of the handler. When moving cows to hoof trimming, injury risks were correlated to job strain and time spent in the risk zone (defined as the area where the handler could be hit by the cow's head or hind legs). The time spent in the risk zone was positively correlated with job strain, age, and experience. Attitudes were not found to have significant impact on safety but were to some extent indirectly involved. These results suggest that the main focus in injury reduction work should be on reducing the time the handler spends in close proximity to animals during aversive procedures and on minimizing cow fear and stress by proper handling techniques and appropriate design of handling facilities.
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| 45. |
- Lloyd, Katy A., et al.
(författare)
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Differential ACPA Binding to Nuclear Antigens Reveals a PAD-Independent Pathway and a Distinct Subset of Acetylation Cross-Reactive Autoantibodies in Rheumatoid Arthritis
- 2019
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 9, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- Rheumatoid arthritis (RA) associated anti-citrullinated protein autoantibodies (ACPA) target a wide range of modified proteins. Citrullination occurs during physiological processes such as apoptosis, yet little is known about the interaction of ACPA with nuclear antigens or apoptotic cells. Since uncleared apoptotic cells and neutrophil extracellular trap (NET) products have been postulated to be central sources of autoantigen and immunostimulation in autoimmune disease, we sought to characterize the anti-nuclear and anti-neutrophil reactivities of ACFA. Serology showed that a subset of anti-CCP2 seropositive RA patients had high reactivity to full-length citrullinated histones. In contrast, seronegative RA patients displayed elevated IgG reactivity to native histone compared to controls, but no citrulline-specific reactivity. Screening of 10 single B-cell derived monoclonal AGFA from RA patients revealed that four ACPA exhibited strong binding to apoptotic cells and three of these had anti-nuclear (ANA) autoantibody reactivity. Modified histones were confirmed to be the primary targets of this anti-nuclear ACPA subset following immunoprecipitation from apoptotic cell lysates. Monoclonal ACPA were also screened for reactivities against stimulated murine and human neutrophils, and all the nuclear-reactive monoclonal ACPA bound to NETs. Intriguingly, one ACPA mAb displayed a contrasting cytoplasmic perinuclear neutrophil binding and may represent a different NET-reactive ACPA subset. Notably, studies of CRISPR-Cas9 PAD4 KO cells and cells from PAD KO mice showed that the cytoplasmic NET-binding was fully dependent on PAD4, whilst nuclear- and histone-mediated NEI reactivity was largely PAD-independent. Our further analysis revealed that the nuclear binding could be explained by consensus-motif driven ACPA cross-reactivity to acetylated histones. Specific acetylated histone peptides targeted by the monoclonal antibodies were identified and the anti-modified protein autoantibody (AMPA) profile of the ACPA was found to correlate with the functional activity of the antibodies. In conclusion, when investigating monoclonal ACPA, we could group ACPA into distinct subsets based on their nuclear binding-patterns and acetylation-mediated binding to apoptotic cells, neutrophils, and NETs. Differential anti-modified protein reactivities of RA-autoantibody subsets could have an important functional impact and provide insights in RA pathogenesis.
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| 46. |
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| 47. |
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| 48. |
- Lundqvist, Peter
(författare)
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Anxiety and Depression Symptoms Among Farmers: The HUNT Study, Norway
- 2016
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Ingår i: Journal of Agromedicine. - 1059-924X .- 1545-0813. ; 21, s. 24-33
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Tidskriftsartikel (refereegranskat)abstract
- Agriculture has undergone profound changes, and farmers face a wide variety of stressors. Our aim was to study the levels of anxiety and depression symptoms among Norwegian farmers compared with other occupational groups. Working participants in the HUNT3 Survey (The Nord-Trondelag Health Study, 2006-2008), aged 19-66.9 years, were included in this cross-sectional study. We compared farmers (women, n = 317; men, n = 1,100) with HUNT3 participants working in other occupational groups (women, n = 13,429; men, n = 10,026), classified according to socioeconomic status. We used the Hospital Anxiety and Depression Scale (HADS) to measure anxiety and depression symptoms. Both male and female farmers had higher levels of depression symptoms than the general working population, but the levels of anxiety symptoms did not differ. The differences in depression symptom levels between farmers and the general working population increased with age. In an age-adjusted logistic regression analysis, the odds ratio (OR) for depression caseness (HADS-D = 8) when compared with the general working population was 1.49 (95% confidence interval [CI]: 1.22-1.83) in men and 1.29 (95% CI: 0.85-1.95) in women. Male farmers had a higher OR of depression caseness than any other occupational group (OR = 1.94, 95% CI: 1.52-2.49, using higher-grade professionals as reference). Female farmers had an OR similar to men (2.00, 95% CI: 1.26-3.17), but lower than other manual occupations. We found that farmers had high levels of depression symptoms and average levels of anxiety symptoms compared with other occupational groups.
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| 49. |
- Lundqvist, Peter, et al.
(författare)
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Barn och fyrhjulingar : riskacceptans och attityder kring användningen av fyrhjulingar på landsbygden ur ett föräldraperspektiv
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Föreliggande studie undersöker attityder och beteenden hos föräldrar och barn som kör fyrhjuling, samt deras erfarenheter av incidenter och skador. Resultaten skall ligga till grund för åtgärdsförslag för olika aktörers fortsatta arbete. Två fokusgrupper, en med ungdomar och en med föräldrar samt en djupintervju med en återförsäljare av fyrhjulingar utfördes inledningsvis. Intervjuerna analyserades och resulterade i sex teman som låg till grund för en intervjuguide som användes för att göra riksomfattande telefonintervjuer med föräldrar och efter medgivande även med en del av deras barn. 50 telefonintervjuer genomfördes under perioden hösten 2015 till våren 2016. Av de intervjuade var 41 vuxna och 9 barn i åldrarna 5–14 år. Resultaten analyserades och svaren för varje fråga sammanställdes, härav framkom 8 teman, vilka beskrivs i rapporten: 1. Användning av fyrhjulingar. 2. Riskmedvetenhet. 3. Information hjälper ej – ”Inte vi men de andra”. 4. Föräldrarnas uppfattning om barns förmåga. 5. Barnens lärande. 6. Barnens perspektiv. 7. Regler och ansvar och 8. Hur är det med riskacceptans? Resultaten visade bland annat att föräldrarna var riskmedvetna och flera visade på en riskacceptans men samtidigt ett stort engagemang för barnens säkerhet. Ett flertal förslag till rekommendationer för att öka säkerheten lämnas i slutet av rapporten.
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| 50. |
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