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- Brennan, S. J., et al.
(författare)
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Photometric and spectroscopic evolution of the interacting transient AT 2016jbu(Gaia16cfr)
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 513:4, s. 5642-5665
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Tidskriftsartikel (refereegranskat)abstract
- We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of MV ∼ −18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s−1 seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s−1 seen in broad absorption from some high-velocity material. Late-time spectra (∼+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He I, and Ca II. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H α among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients.
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| 3. |
- Halme, P., et al.
(författare)
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Challenges of ecological restoration : Lessons from forests in northern Europe
- 2013
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 167, s. 248-256
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Forskningsöversikt (refereegranskat)abstract
- The alarming rate of ecosystem degradation has raised the need for ecological restoration throughout different biomes and continents. North European forests may appear as one of the least vulnerable ecosystems from a global perspective, since forest cover is not rapidly decreasing and many ecosystem services remain at high level. However, extensive areas of northern forests are heavily exploited and have lost a major part of their biodiversity value. There is a strong requirement to restore these areas towards a more natural condition in order to meet the targets of the Convention on Biological Diversity. Several northern countries are now taking up this challenge by restoring forest biodiversity with increasing intensity. The ecology and biodiversity of boreal forests are relatively well understood making them a good model for restoration activities in many other forest ecosystems. Here we introduce northern forests as an ecosystem, discuss the historical and recent human impact and provide a brief status report on the ecological restoration projects and research already conducted there. Based on this discussion, we argue that before any restoration actions commence, the ecology of the target ecosystem should be established with the need for restoration carefully assessed and the outcome properly monitored. Finally, we identify the most important challenges that need to be solved in order to carry out efficient restoration with powerful and long-term positive impacts on biodiversity: coping with unpredictability, maintaining connectivity in time and space, assessment of functionality, management of conflicting interests and social restrictions and ensuring adequate funding. © 2013 Elsevier Ltd.
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| 8. |
- Madar Johansson, Miralda, et al.
(författare)
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The binding mechanism of the virulence factor Streptococcus suis adhesin P subtype to globotetraosylceramide is associated with systemic disease
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:42, s. 14305-14324
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus suis is part of the pig commensal microbiome but strains can also be pathogenic, causing pneumonia and meningitis in pigs as well as zoonotic meningitis. According to genomic analysis, S. suis is divided into asymptomatic carriage, respiratory and systemic strains with distinct genomic signatures. Because the strategies to target pathogenic S. suis are limited, new therapeutic approaches are needed. The virulence factor S. suis adhesin P (SadP) recognizes the galabiose Gal alpha 1-4Gal-oligosaccharide. Based on its oligosaccharide fine specificity, SadP can be divided into subtypes P-N and P-O. We show here that subtype P-N is distributed in the systemic strains causing meningitis, whereas type P-O is found in asymptomatic carriage and respiratory strains. Both types of SadP are shown to predominantly bind to pig lung globotriaosylceramide (Gb3). However, SadP adhesin from systemic subtype P-N strains also binds to globotetraosylceramide (Gb4). Mutagenesis studies of the galabiose-binding domain of type P-N SadP adhesin showed that the amino acid asparagine 285, which is replaced by an aspartate residue in type P-O SadP, was required for binding to Gb4 and, strikingly, was also required for interaction with the glycomimetic inhibitor phenylurea-galabiose. Molecular dynamics simulations provided insight into the role of Asn-285 for Gb4 and phenylurea-galabiose binding, suggesting additional hydrogen bonding to terminal GalNAc of Gb4 and the urea group. Thus, the Asn-285-mediated molecular mechanism of type P-N SadP binding to Gb4 could be used to selectively target S. suis in systemic disease without interfering with commensal strains, opening up new avenues for interventional strategies against this pathogen.
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| 9. |
- Nyholm, R., et al.
(författare)
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Submicrometer-resolution photoelectron-spectroscopy at MAX Lab
- 1989
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 60:7, s. 2168-2171
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Tidskriftsartikel (refereegranskat)abstract
- The design of a photoemission microprobe beamline at the MAX laboratory is presented. The beamline will utilize the radiation from a 26 period undulator on the 550-MeV MAX storage ring. The beamline will be capable of providing about 1010 photons/s of monochromatized radiation (bandwidth better than 0.25 eV) in the energy range of 20 to 150 eV focused into a submicrometer focal spot. It will be used for scanning photoemission experiments with a lateral resolution better than 1 μm. The optical system is comprised of a plane-grating monochromator with a Kirkpatrick-Baez objective and a specially designed ellipsoidal focusing mirror.
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| 10. |
- Orädd, Greger, et al.
(författare)
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NMR studies of binary and ternary systems of phosphatidylcholines
- 2007
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Ingår i: European Biophysics Journal, 2007 July, Volume 36, Supplement 1. ; , s. 1-278
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Lipid lateral segregation in biomimicking model membranes has recently become a topic of great interest due to the biological coupling to the concept of functional rafts. In the studies of liquid-liquid phase coexistence it is found that lateral phase separation into liquid ordered and liquid disordered phases takes place in ternary systems consisting of one unsaturated and one saturated lipid, together with a sterol. The phase behavior is critically dependent on the components with respect to chain length, degree of unsaturation and sterol structure and the driving force of the phase separation is closely related to the ordering effect of the sterol on the lipid chains. This study presents NMR data for binary and ternary systems composed of mixtures of sphingomyelins, phosphatidylcholines and cholesterol. Order parameters were obtained from perdeuterated chains in the saturated lipid and diffusion data of both the saturated and unsaturated lipids were measured with the pulsed field gradient NMR method. Data were analyzed with regard to phase separation into liquid and solid phases.
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