| 1. |
- Henschen, Jonatan, 1989-
(författare)
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Bacterial adhesion to polyelectrolyte modified materials based on nanocellulose
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since the introduction of materials based on cellulose nanofibrils (CNFs), these materials have been studied extensively and are suggested to be suitable for use in, for example, hygiene and health care products. A property not very well studied but that could further increase the usability of CNF products is the possibility of controlling bacterial adhesion to the materials. Controlling and fine-tuning the bacterial adhesion makes it possible to produce contact-active antibacterial materials as well as anti-adhesive materials.The current thesis shows how the number of bacteria adhering to CNF-based materials can be altered through the adsorption of polyelectrolyte multilayers. Polyvinylamine (PVAm) and polyacrylic acid (PAA) were adsorbed in multilayers to achieve differently charged materials. The CNF substrates consisted of both crosslinked and non-crosslinked films with different surface charges and structures as well as porous aerogels.The results show the possibility of adsorbing PVAm/PAA to recharge the surfaces and construct multilayers. The polyelectrolyte adsorption was affected both by crosslinking and by changing the surface charge of the CNF films. Increasing the surface charge resulted in a decreased PVAm adsorption after the first polymer layer. Crosslinking the films resulted in a low initial PVAm adsorption, but as more layers were adsorbed, the PVAm adsorption increased similarly to the non-crosslinked films. The PVAm adsorption to the aerogels was lower than expected, taking into account their high surface area and surface charge, possibly due to crowding effects on the surface due to geometric limitations.Only the CNF films with the lowest surface charge and the aerogels adsorbed high numbers of bacteria from bacterial suspensions. The bacterial adsorption to the films was affected by the surface charge, the PAA adsorption and the PVAm adsorption, with a higher net surface charge leading to higher bacterial adsorption. The aerogels efficiently removed bacteria from the bacterial suspensions by adsorbing them onto their surface, with some samples removing over 99.9 % of the bacteria. The results presented in this thesis are believed to lead to a better understanding of both polyelectrolyte adsorption on CNF materials and bacterial adhesion to CNF materials and how polyelectrolyte multilayer adsorption can alter it.
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| 2. |
- Larsson, Josefin, et al.
(författare)
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Spectral components in the bright, long GRB 061007 : properties of the photosphere and the nature of the outflow
- 2011
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 414:3, s. 2642-2649
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Tidskriftsartikel (refereegranskat)abstract
- We present a time-resolved spectral analysis of the bright, long GRB 061007 (z = 1.261) using Swift and Suzaku data. We find that the prompt emission of the burst can be equally well explained by a photospheric component together with a power law as by a Band function, and we explore the implications of the former model. The photospheric component, which we model with a multicolour blackbody, dominates the spectra and has a very stable shape throughout the burst. This component provides a natural explanation for the hardness-intensity correlation seen within the burst and also allows us to estimate the bulk Lorentz factor and the radius of the photosphere. The power-law component dominates the fit at high energies and has a nearly constant slope of -1.5. We discuss the possibility that this component is of the same origin as the high-energy power laws recently observed in some Fermi bursts.
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| 3. |
- Preece, R., et al.
(författare)
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The First Pulse of the Extremely Bright GRB 130427A : A Test Lab for Synchrotron Shocks
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 343:6166, s. 51-54
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-ray burst (GRB) 130427A is one of the most energetic GRBs ever observed. The initial pulse up to 2.5 seconds is possibly the brightest well-isolated pulse observed to date. A fine time resolution spectral analysis shows power-law decays of the peak energy from the onset of the pulse, consistent with models of internal synchrotron shock pulses. However, a strongly correlated power-law behavior is observed between the luminosity and the spectral peak energy that is inconsistent with curvature effects arising in the relativistic outflow. It is difficult for any of the existing models to account for all of the observed spectral and temporal behaviors simultaneously.
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| 4. |
- Ryde, Felix, et al.
(författare)
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IDENTIFICATION AND PROPERTIES OF THE PHOTOSPHERIC EMISSION IN GRB090902B
- 2010
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Ingår i: The Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 709:2, s. l172-L177
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Tidskriftsartikel (refereegranskat)abstract
- The Fermi Gamma-ray Space Telescope observed the bright and long GRB090902B, lying at a redshift of z = 1.822. Together the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM) cover the spectral range from 8 keV to >300 GeV. Here we show that the prompt burst spectrum is consistent with emission from the jet photosphere combined with nonthermal emission described by a single power law with photon index -1.9. The photosphere gives rise to a strong quasi-blackbody spectrum which is somewhat broader than a single Planck function and has a characteristic temperature of similar to 290 keV. We model the photospheric emission with a multicolor blackbody, and its shape indicates that the photospheric radius increases at higher latitudes. We derive the averaged photospheric radius R-ph = (1.1 +/- 0.3) x 10(12) Y-1/4 cm and the bulk Lorentz factor of the flow, which is found to vary by a factor of 2 and has a maximal value of Gamma = 750 Y-1/4. Here, Y is the ratio between the total fireball energy and the energy emitted in the gamma rays. We find that during the first quarter of the prompt phase the photospheric emission dominates, which explains the delayed onset of the observed flux in the LAT compared to the GBM. We interpret the broadband emission as synchrotron emission at R similar to 4 x 10(15) cm. Our analysis emphasizes the importance of having high temporal resolution when performing spectral analysis on gamma-ray bursts, since there is strong spectral evolution.
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| 5. |
- Soffitta, Paolo, et al.
(författare)
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XIPE : the X-ray imaging polarimetry explorer
- 2013
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 36:3, s. 523-567
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Tidskriftsartikel (refereegranskat)abstract
- X-ray polarimetry, sometimes alone, and sometimes coupled to spectral and temporal variability measurements and to imaging, allows a wealth of physical phenomena in astrophysics to be studied. X-ray polarimetry investigates the acceleration process, for example, including those typical of magnetic reconnection in solar flares, but also emission in the strong magnetic fields of neutron stars and white dwarfs. It detects scattering in asymmetric structures such as accretion disks and columns, and in the so-called molecular torus and ionization cones. In addition, it allows fundamental physics in regimes of gravity and of magnetic field intensity not accessible to experiments on the Earth to be probed. Finally, models that describe fundamental interactions (e.g. quantum gravity and the extension of the Standard Model) can be tested. We describe in this paper the X-ray Imaging Polarimetry Explorer (XIPE), proposed in June 2012 to the first ESA call for a small mission with a launch in 2017. The proposal was, unfortunately, not selected. To be compliant with this schedule, we designed the payload mostly with existing items. The XIPE proposal takes advantage of the completed phase A of POLARIX for an ASI small mission program that was cancelled, but is different in many aspects: the detectors, the presence of a solar flare polarimeter and photometer and the use of a light platform derived by a mass production for a cluster of satellites. XIPE is composed of two out of the three existing JET-X telescopes with two Gas Pixel Detectors (GPD) filled with a He-DME mixture at their focus. Two additional GPDs filled with a 3-bar Ar-DME mixture always face the Sun to detect polarization from solar flares. The Minimum Detectable Polarization of a 1 mCrab source reaches 14 % in the 2-10 keV band in 10(5) s for pointed observations, and 0.6 % for an X10 class solar flare in the 15-35 keV energy band. The imaging capability is 24 arcsec Half Energy Width (HEW) in a Field of View of 14.7 arcmin x 14.7 arcmin. The spectral resolution is 20 % at 6 keV and the time resolution is 8 mu s. The imaging capabilities of the JET-X optics and of the GPD have been demonstrated by a recent calibration campaign at PANTER X-ray test facility of the Max-Planck-Institut fur extraterrestrische Physik (MPE, Germany). XIPE takes advantage of a low-earth equatorial orbit with Malindi as down-link station and of a Mission Operation Center (MOC) at INPE (Brazil). The data policy is organized with a Core Program that comprises three months of Science Verification Phase and 25 % of net observing time in the following 2 years. A competitive Guest Observer program covers the remaining 75 % of the net observing time.
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| 6. |
- Sundelöf, Andreas, et al.
(författare)
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Fisk- och skaldjursbestånd i hav och sötvatten 2021 : Resursöversikt
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I rapporten kan du ta del av bedömningen som görs av situationen för bestånd som regleras inom ramen för EU:s gemensamma fiskeripolitik (GFP). Bedömningarna baseras på det forskningssamarbete och den rådgivning som sker inom det Internationella Havsforskningsrådet (ICES). Sammantaget redovisas tillståndet för 107 bestånd av 48 fisk- och skaldjursarter.De bestånd som förvaltas nationellt baseras på de biologiska underlagen, och rådgivningen i huvudsak på den forskning och övervakning samt analys som bedrivs av Institutionen för akvatiska resurser vid Sveriges lantbruksuniversitet (SLU Aqua) samt yrkesfiskets rapportering.Rapporten är en beställning från Havs- och vattenmyndigheten (HaV) till Sveriges lantbruksuniversitet (SLU) och utgör ett viktigt kunskapsunderlag till myndighetens arbete. Den uppfyller de krav som finns inom EU:s gemensamma fiskeripolitik om att basera förvaltningen på bästa tillgängliga vetenskap. Denna rapport är också ett stöd till det arbete som beskrivs närmare i strategin för framtidens fiske och tillhörande handlingsplaner för vattenbruk, yrkes- och fritidsfiske som HaV och Jordbruksverket har tagit fram i dialog med fiskets och vattenbrukets intressenter.
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| 7. |
- Abellán, F. J., et al.
(författare)
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Very Deep inside the SN 1987A Core Ejecta : Molecular Structures Seen in 3D
- 2017
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics Publishing. - 2041-8205 .- 2041-8213. ; 842:2
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Tidskriftsartikel (refereegranskat)abstract
- Most massive stars end their lives in core-collapse supernova explosions and enrich the interstellar medium with explosively nucleosynthesized elements. Following core collapse, the explosion is subject to instabilities as the shock propagates outward through the progenitor star. Observations of the composition and structure of the innermost regions of a core-collapse supernova provide a direct probe of the instabilities and nucleosynthetic products. SN 1987A in the Large Magellanic Cloud is one of very few supernovae for which the inner ejecta can be spatially resolved but are not yet strongly affected by interaction with the surroundings. Our observations of SN 1987A with the Atacama Large Millimeter/submillimeter Array are of the highest resolution to date and reveal the detailed morphology of cold molecular gas in the innermost regions of the remnant. The 3D distributions of carbon and silicon monoxide (CO and SiO) emission differ, but both have a central deficit, or torus-like distribution, possibly a result of radioactive heating during the first weeks ("nickel heating"). The size scales of the clumpy distribution are compared quantitatively to models, demonstrating how progenitor and explosion physics can be constrained.
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| 8. |
- Adriani, O., et al.
(författare)
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The gamma-400 space observatory : Status and perspectives
- 2014
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- The present design of the new space observatory GAMMA-400 is presented in this paper. The instrument has been designed for the optimal detection of gamma rays in a broad energy range (from ∼100 MeV up to 3 TeV), with excellent angular and energy resolution. The observatory will also allow precise and high statistic studies of the electron component in the cosmic rays up to the multi TeV region, as well as protons and nuclei spectra up to the knee region. The GAMMA-400 observatory will allow to address a broad range of science topics, like search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts and charged cosmic rays acceleration and diffusion mechanism up to the knee.
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| 9. |
- Ahlgren, Björn, et al.
(författare)
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A Search for Lensed Gamma-Ray Bursts in 11 yr of Observations by Fermi GBM
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 897:2
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Tidskriftsartikel (refereegranskat)abstract
- Macrolensing of gamma-ray bursts (GRBs) is expected to manifest as a GRB recurring with the same light curve and spectrum as a previous one, but with a different flux and a slightly offset position. Identifying such lensed GRBs may give important information about the lenses, the cosmology, and the GRBs themselves. Here we present a search for lensed GRBs among similar to 2700 GRBs observed by the Fermi Gamma-ray Burst Monitor during 11 yr of operations. To identify lensed GRBs, we perform initial cuts on position, time-averaged spectral properties, and relative duration. We then use the cross-correlation function to assess the similarity of light curves, and finally we analyze the time-resolved spectra of the most promising candidates. We find no convincing lens candidates. The most similar pairs are single-pulsed GRBs with relatively few time bins for the spectral analysis. This is best explained by similarities within the GRB population rather than lensing. However, the null result does not rule out the presence of macrolensed GRBs in the sample. In particular, we find that observational uncertainties and Poisson fluctuations can lead to significant differences within a pair of lensed GRBs.
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| 10. |
- Ahlgren, Björn, et al.
(författare)
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Confronting GRB prompt emission with a model for subphotospheric dissipation
- 2015
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Ingår i: Monthly Notices of the Royal Astronomical Society: Letters. - : Oxford University Press. - 1745-3925 .- 1745-3933. ; 454:1, s. L31-L35
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Tidskriftsartikel (refereegranskat)abstract
- The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. Here, we fit Fermi GRB data with a photospheric emission model which includes dissipation of the jet kinetic energy below the photosphere. The resulting spectra are dominated by Comptonization and contain no significant contribution from synchrotron radiation. In order to fit to the data, we span a physically motivated part of the model's parameter space and create DREAM (Dissipation with Radiative Emission as A table Model), a table model for XSPEC. We show that this model can describe different kinds of GRB spectra, including GRB 090618, representing a typical Band function spectrum, and GRB 100724B, illustrating a double peaked spectrum, previously fitted with a Band+blackbody model, suggesting they originate from a similar scenario. We suggest that the main difference between these two types of bursts is the optical depth at the dissipation site.
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| 11. |
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| 12. |
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| 13. |
- Ahlgren, Björn, et al.
(författare)
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Investigating Subphotospheric Dissipation in Gamma-Ray Bursts Using Joint Fermi-Swift Observations
- 2019
-
Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 880:2
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Tidskriftsartikel (refereegranskat)abstract
- The jet photosphere has been proposed as the origin for the gamma-ray burst (GRB) prompt emission. In many such models, characteristic features in the spectra appear below the energy range of the Fermi Gamma-ray Burst Monitor (GBM) detectors, so joint fits with X-ray data are important in order to assess the photospheric scenario. Here we consider a particular photospheric model which assumes localized subphotospheric dissipation by internal shocks in a non-magnetized outflow. We investigate it using Bayesian inference and a sample of eight GRBs with known redshifts which are observed simultaneously with Fermi GBM and the Swift X-ray Telescope (XRT). This provides us with an energy range of 0.3. keV-40. MeV and much tighter parameter constraints. We analyze 32 spectra and find that 16 are well described by the model. We also find that the estimates of the bulk Lorentz factor, Gamma, and the fireball luminosity, L-0,L-52, decrease while the fraction of dissipated energy, epsilon(d), increases in the joint fits compared to GBM-only fits. These changes are caused by a small excess of counts in the XRT data, relative to the model predictions from fits to GBM-only data. The fact that our limited implementation of the physical scenario yields 50% accepted spectra is promising, and we discuss possible model revisions in the light of the new data. Specifically, we argue that the inclusion of significant magnetization, as well as removing the assumption of internal shocks, will provide better fits at low energies.
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| 14. |
- Ahlgren, Björn, 1990-
(författare)
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Subphotospheric dissipation in gamma-ray bursts observed by the Fermi Gamma-ray Space Telescope
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gamma-ray bursts (GRBs) are the brightest events in the Universe, for a short time outshining the rest of the Universe combined, as they explode with isotropic equivalent luminosities up to $10^{54}$ erg s$^{-1}$. These events are believed to be connected to supernovae and to binary compact object mergers, such as binary neutron stars or neutron star -- black hole systems. The origin of the so-called prompt emission in GRBs remains an unsolved problem, although some progress is being made. Spectral analysis of prompt emission has traditionally been performed with the Band function, an empirical model with no physical interpretation, and it is just recently that physical models have started to be fitted to data. This thesis presents spectral analysis of GRB data from the Fermi Gamma-ray Space Telescope using a physical model for subphotospheric dissipation. The model is developed using a numerical code and implemented as a table model in {\scriptsize XSPEC}. Paper \rom{1} presents the model and provides a proof-of-concept of fitting GRB data with such a model. Specifically, two GRBs are fitted and compared with the corresponding Band function fits. In paper \rom{2}, a sample of 37 bursts are fitted with an extended version of the model and improved analysis tools. Overall, about a third of the fitted spectra can be described by the model. From these fits it is concluded that the scenario of subphotospheric dissipation can describe all spectral shapes present in the sample. The key characteristic of the spectra that are not fitted by the model is that they are very luminous. Within the context of the model, this suggests that the assumption of internal shocks as a dissipation mechanism cannot explain the full population of GRBs. Alternatively, additional emission components may required. The thesis concludes that subphotospheric dissipation is viable as a possible origin of GRB prompt emission. Furthermore, it shows the importance of using physically motivated models when analysing GRBs.
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| 15. |
- Ahlgren, Björn, et al.
(författare)
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Testing a model for subphotospheric dissipation in GRBs: fits to Fermi data constrain the dissipation scenario
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 485, s. 474-497
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that the prompt emission in gamma-ray bursts (GRBs) could be described by radiation from the photosphere in a hot fireball. Such models must be tested by directly fitting them to data. In this work we use data from the Fermi Gamma-ray Space Telescope and consider a specific photospheric model, in which the kinetic energy of a low-magnetization outflow is dissipated locally by internal shocks below the photosphere. We construct a table model with a physically motivated parameter space and fit it to time-resolved spectra of the 36 brightest Fermi GRBs with a known redshift. We find that about two-thirds of the examined spectra cannot be described by the model, as it typically underpredicts the observed flux. However, since the sample is strongly biased towards bright GRBs, we argue that this fraction will be significantly lowered when considering the full population. From the successful fits we find that the model can reproduce the full range of spectral slopes present in the sample. For these cases we also find that the dissipation consistently occurs at a radius of ∼1012 cm and that only a few per cent efficiency is required. Furthermore, we find a positive correlation between the fireball luminosity and the Lorentz factor. Such a correlation has been previously reported by independent methods. We conclude that if GRB spectra are due to photospheric emission, the dissipation cannot only be the specific scenario we consider here.
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| 16. |
- Al-Adhami, Maissa, 1972-, et al.
(författare)
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Can an extended civic orientation course improve newly settled migrants’ health literacy and social capital? : A quasi-experimental study
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Structural and contextual factors such as limited work opportunities, restrictive integration policies and discrimination negatively affect the health and well-being of newly settled refugee migrants in receiving high-income countries. Health promotion initiatives aiming to facilitate access to work and integration by enhancing individual-level health resources have been tried out within the Swedish Civic Orientation. However, longitudinal evaluations of these interventions are rare. The aim of the current study was to compare the effectiveness of a regular and an extended civic orientation course with added health communication and examine whether the latter would improve self-rated health and psychological well-being, health literacy, and social capital among newly settled refugee migrants in Sweden. Pre-and post-assessment questionnaires were collected from the intervention group receiving the extended course (n=143) and a control group receiving the regular course (n=173). Linear mixed models and Chi-square analyses showed a significant increase with a small effect size (0.21) in health literacy in the intervention group. However, there were no significant changes in emotional and practical support, general self-rated health, or psychological well-being. The findings indicate that added health communication provided within the Swedish civic orientation can increase health literacy. However, further longitudinal studies are needed to confirm the sustainability of the observed effect and examine whether these short-term improvements in health literacy translate to long-term benefits in other outcomes such as health and integration of newly settled refugee migrants.
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| 17. |
- Al Adhami, Maissa, Doctoral candidate, 1972-, et al.
(författare)
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Can extended health communication improve newly settled refugees’ health literacy? A quasi-experimental study from Sweden
- 2024
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Ingår i: Health Promotion International. - : Oxford University Press. - 0957-4824 .- 1460-2245. ; 39:2
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Tidskriftsartikel (refereegranskat)abstract
- Structural and contextual factors such as limited work and housing opportunities negatively affect the health and well-being of newly settled refugee migrants in receiving high-income countries. Health promotion initiatives aiming at strengthening health and integration have been tried out within the Swedish Introduction program for refugee migrants. However, longitudinal evaluations of these interventions are rare. The aim of the current study was to compare the effectiveness of a regular and an extended civic orientation course with added health communication and examine whether the latter would improve self-rated health and psychological well-being, health literacy and social capital among newly settled refugee migrants in Sweden. Pre- and post-assessment questionnaires were collected from the intervention group receiving the extended course (n = 143) and a control group receiving the regular course (n = 173). Linear mixed models and chi-square analyses showed a significant increase with a small effect size (0.21) in health literacy in the intervention group. However, there were no significant changes in emotional and practical support, general self-rated health or psychological well-being. The findings indicate that added health communication provided embedded in the civic orientation course can increase health literacy. However, further longitudinal studies are needed to confirm the sustainability of the observed effect and examine whether these short-term improvements in health literacy translate to long-term advances in health and integration.
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| 18. |
- Al Adhami, Maissa, Doctoral candidate, 1972-, et al.
(författare)
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Can extended health communication improve newly settled refugees' health literacy? A quasi-experimental study from Sweden
- 2024
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Ingår i: Health Promotion International. - : Oxford University Press. - 0957-4824 .- 1460-2245. ; 39:2
-
Tidskriftsartikel (refereegranskat)abstract
- Structural and contextual factors such as limited work and housing opportunities negatively affect the health and well-being of newly settled refugee migrants in receiving high-income countries. Health promotion initiatives aiming at strengthening health and integration have been tried out within the Swedish Introduction program for refugee migrants. However, longitudinal evaluations of these interventions are rare. The aim of the current study was to compare the effectiveness of a regular and an extended civic orientation course with added health communication and examine whether the latter would improve self-rated health and psychological well-being, health literacy and social capital among newly settled refugee migrants in Sweden. Pre- and post-assessment questionnaires were collected from the intervention group receiving the extended course (n = 143) and a control group receiving the regular course (n = 173). Linear mixed models and chi-square analyses showed a significant increase with a small effect size (0.21) in health literacy in the intervention group. However, there were no significant changes in emotional and practical support, general self-rated health or psychological well-being. The findings indicate that added health communication provided embedded in the civic orientation course can increase health literacy. However, further longitudinal studies are needed to confirm the sustainability of the observed effect and examine whether these short-term improvements in health literacy translate to long-term advances in health and integration.
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| 19. |
- Al Adhami, Maissa, 1972-, et al.
(författare)
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"This course is like a compass to us" : a qualitative study on newly settled migrants' perceptions of civic and health orientation in Sweden
- 2021
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Ingår i: BMC Public Health. - : BioMed Central (BMC). - 1471-2458. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Migrants face structural, socio-political barriers in their resettlement processes that negatively affect their health. Migration also adversely impacts resources such as social capital and health literacy that are of importance for health and integration into society. Hence, there is a need for health promotion in the early post-migration phase. In Sweden, newly settled refugee migrants who have received a residence permit are offered an Introduction programme including a civic orientation course. The program is intended to facilitate access to the labour market and promote integration. The aim of the study was to explore participants' perceptions and experiences of a civic orientation course with added health communication. Methods We performed six focus group discussions: two in Arabic, two in Farsi and two in Somali. The discussions were facilitated by native speaking moderators. Participants were 32 men and women recruited from civic orientation classes in the county of Stockholm. We used an interview guide with semi-structured questions. The data were analysed using a method for content analysis for focus group discussions. Results Three main categories were identified: (1) 'The course gives valuable information but needs adjustments', which includes that the civic and health orientation is needed earlier, during the asylum phase, and that planning and course content need adjustments. (2) 'The health communication inspired participants to focus on their health', which includes that the health communication was useful and inspired uptake of healthier habits. (3) 'Participation in the course promoted independence and self-confidence', which includes that the course gave insights into society and values in Sweden, and promoted independence and new social contacts. Conclusion This study adds knowledge about the users' perspectives on the potential of civic orientation to promote the health and integration of newly settled migrants, describing ways in which civic orientation with added health communication promoted health and empowerment. However, the content and delivery of the course need adjustment to better fit the migrants' life situations and varying pre-existing knowledge.
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| 20. |
- Almung, Magnus, et al.
(författare)
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I solitärens skugga : Nyttobyggnadens kreativa restaurering
- 2015
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Rapport (populärvet., debatt m.m.)abstract
- Ekonomibyggnader har alltid behövts för de huvudbyggnader som finns inom våra bevarade kulturmiljöer. Några nyttobyggnader uppskattas och används fortfarande, andra betraktas som problematiska överloppsbyggnader, många rivs. Alltför få har dokumenterats eller fått sin historia klarlagd vilket undanhållit viktig kunskap om samhällets framväxt. Vi vill synliggöra och betona vikten av att bevara och utveckla hela bebyggelsemiljöer, ofta med ett antal hus utöver huvudbyggnaden och tillhörande yttre miljö i staden eller på landet. Denna rapport visar kursdeltagarnas projektarbeten om nyttobyggnader. De har dokumenterat med traditionella och nya arbetsmetoder, inventerat och intervjuat, läst och besökt arkiv, värderat, analyserat och därefter föreslagit hur man ska ta hand om och utveckla nyttobyggnaderna i sina kulturmiljöer.
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| 21. |
- Alp, Dennis, MSc, 1992-
(författare)
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An X-Ray View of Core-collapse Supernovae
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A core-collapse supernova (CCSN) is an astronomical explosion that indicates the death of a massive star. From observations, it is clear that a large fraction of all massive stars undergoes supernova (SN) explosions, but describing how SNe explode has remained a challenge for many decades. A key piece of the puzzle is the properties of the progenitor star.The attached papers focus on comparing theoretical predictions with observations, primarily observations of SN 1987A. It is the closest observed SN in more than four centuries, allowing for more detailed studies than for any other SN. The papers investigate different aspects of the SN phenomenon. These individual studies are observationally diverse, but all attempt to answer different questions that are important for our understanding of the SN process.The properties of the progenitor star set the stage for the SN. Paper III compares SN models based on different progenitor stars with early X-ray and gamma-ray observations of SN 1987A. The results help constrain the evolution of the progenitor. In Paper IV, we searched for SN shock breakouts (SBOs), which are the first electromagnetic signals from CCSNe. The discovered candidates convey information about the progenitors, test the SBO theory, and indicate the presence of other types of X-ray transients.The SN explosion mechanism itself is also integral to the analysis in Paper III. The explosion models used in Paper III rely on some of the most recent three-dimensional neutrino-driven SN models. The results lend further support to the hypothesis that delayed neutrino heating is sufficient to explode the vast majority of all CCSNe.Much can also be learned about SNe by studying their remnants. The remains of the core, the compact remnant, in SN 1987A has not yet been detected. We have investigated how a compact object can remain hidden in the ejecta in Paper I, using an absorption model from Paper II. We favor a scenario where the compact object is a neutron star that is quiescent, dust-obscured, and only emitting thermal emission. Paper V is another study of SN 1987A, but focuses on the X-ray emission from the ongoing interactions between the ejecta and circumstellar medium (CSM). The X-ray emission is primarily generated by thermal processes in shocks produced by collisions between the ejecta and the CSM. We found no evidence for any contribution from relativistic particles or a neutron star.Our description of CCSNe continues to improve but many questions remain unanswered. Future observations will further our knowledge and the models we have studied can be used for continued analyses. The next generation of X-ray missions is very promising and a Galactic SN, which would greatly accelerate the entire research field, could occur at any time.
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| 22. |
- Alp, Dennis, MSc, 1992-, et al.
(författare)
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Blasts from the Past : Supernova Shock Breakouts among X-Ray Transients in the XMM-Newton Archive
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 896:1
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Tidskriftsartikel (refereegranskat)abstract
- The first electromagnetic signal from a supernova (SN) is released when the shock crosses the progenitor surface. This shock breakout (SBO) emission provides constraints on progenitor and explosion properties. Observationally, SBOs appear as minute- to hour-long extragalactic X-ray transients. They are challenging to detect and only one SBO has been observed to date. Here, we search the XMM-Newton archive and find 12 new SN SBO candidates. We identify host galaxies to nine of these at estimated redshifts of 0.1-1. The SBO candidates have energies of similar to 10(46)erg, timescales of 30-3000 s, and temperatures of 0.1-1 keV. They are all consistent with being SN SBOs, but some may be misidentified Galactic foreground sources or other extragalactic objects. SBOs from blue supergiants agree well with most of the candidates. However, a few could be SBOs from Wolf-Rayet stars surrounded by dense circumstellar media, whereas two are more naturally explained as SBOs from red supergiants. The observations tentatively support non-spherical SBOs and are in agreement with asymmetries predicted by recent three-dimensional SN explosion simulations. eROSITA may detect similar to 2 SBOs per year, which could be detected in live analyses and promptly followed up.
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| 23. |
- Alp, Dennis, MSc, 1992-
(författare)
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Core-collapse Supernovae : Theory vs. Observations
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A core-collapse supernova (CCSN) is an astronomical explosion that indicates the death of a massive star. The iron core of the star collapses into either a neutron star or a black hole while the rest of the material is expelled at high velocities. Supernovae (SNe) are important for the chemical evolution of the Universe because a large fraction of the heavier elements such as oxygen, silicon, and iron are liberated by CCSN explosions. Another important role of SNe is that the ejected material seed the next generation of stars and planets. From observations, it is clear that a large fraction of all massive stars undergoes SN explosions, but describing how SNe explode has remained a challenge for many decades.The attached papers focus on comparing theoretical predictions with observations, primarily observations of SN 1987A. The compact remnant in SN 1987A has not yet been detected and we have investigated how a compact object can remain hidden in the ejecta (Paper I and II). Because of the high opacity of the metal-rich ejecta, the direct X-ray observations are not very constraining even for potentially favorable viewing angles. However, the combined observations still strongly constrain fallback accretion and put a limit on possible pulsar wind activity. The thermal surface emission from a neutron star is consistent with the observations if our line of sight is dust-obscured, and only marginally consistent otherwise. Future observations provide promising opportunities for detecting the compact object.We have also compared the most recent three-dimensional neutrino-driven SN models that are based on explosion simulations with early X-ray and gamma-ray observations of SN 1987A (Paper III). The models that are designed to match SN 1987A fit the data well, but not all tensions can be explained by choosing a suitable viewing angle. More generally, the asymmetries do not affect the early emission qualitatively and different progenitors of the same class result in similar early emission. We also find that the progenitor metallicity is important for the low-energy X-ray cuto↵. Current instruments should be able to detect this emission from SNe at distances of 3–10 Mpc, which correspond to distances slightly beyond the Local Group.
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| 24. |
- Alp, Dennis, et al.
(författare)
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The 30 Year Search for the Compact Object in SN 1987A
- 2018
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 864:2
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Tidskriftsartikel (refereegranskat)abstract
- Despite more than 30 years of searching, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy (0.1 x 10(-26) erg s(-1) cm(-2) Hz(-1)) at 213 GHz, 1 L-circle dot (6 x 10(-29) erg s(-1) cm(-2) Hz(-1)) in the optical if our line of sight is free of ejecta dust, and 10(36) erg s(-1) (2 x 10(-30) erg s(-1) cm(-2) Hz(-1) ) in 2-10 keV X-rays. Our X-ray limits are an order of magnitude less constraining than previous limits because we use a more realistic ejecta absorption model based on three-dimensional neutrino-driven SN explosion models. The allowed bolometric luminosity of the compact object is 22 L-circle dot if our line of sight is free of ejecta dust, or 138L(circle dot) if dust-obscured. Depending on assumptions, these values limit the effective temperature of a neutron star (NS) to <4-8 MK and do not exclude models, which typically are in the range 3-4 MK. For the simplest accretion model, the accretion rate for an efficiency 77 is limited to <10(-11) eta(-1) M-circle dot yr(-1), which excludes most predictions. For pulsar activity modeled by a rotating magnetic dipole in vacuum, the limit on the magnetic field strength (B) for a given spin period (P) is B less than or similar to 10(14) P-2 G s(-2), which firmly excludes pulsars comparable to the Crab. By combining information about radiation reprocessing and geometry, we infer that the compact object is a dust-obscured thermally emitting NS, which may appear as a region of higher-temperature ejecta dust emission.
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| 25. |
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