| 1. |
- Hallström, Henrik, 1975-
(författare)
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VISIONER OM FORMATIVA PRAKTIKER : Lärares och elevers levda erfarenheter av formativ bedömning och bedömningsmatriser i skolans fysikundervisning
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the wake of declining student performance and interest in science education, efforts to improve the quality of science teaching have intensified, including physics education. A recurring proposal to improve physics teaching is the use of formative assessment. Policy reforms tend to view the implementation of formative assessment as easy, but studies indicate that integrating these strategies into teachers’ practices can be challenging. Using a phenomenological approach and hermeneutic reflections, the present study explores the opportunities and challenges that teachers’ and students’ experience when implementing formative assessments in the physics classroom. For example, teachers may encounter resistance from their students and colleagues with different expectations of physics teaching, limiting teachers’ opportunities to ‘break free’ from established traditions. However, the study also highlights opportunities for physics teachers to evolve by taking risks and embracing formative assessment as an overarching learning assessment approach. Furthermore, the present study confirms the results of previous research indicating that students may see assessment rubrics in a positive light as their use can clarify teachers’ expectations and reduce uncertainty in this regard. However, the results of the present study also show that students may approach rubrics only as mechanical and strategic tools to obtain their desired grades, which risks conveying the message to students that physics knowledge is quantitative in nature. The students’ experiences also demonstrated that the use of rubrics could cause stress and anxiety, limiting the formative potential of rubrics. The results of the study are discussed in relation to the support that teachers and students need in implementing formative assessment and rubric use, and they have implications for teachers’ assessment literacy, including their ability to implement formative assessments in relation to different purposes of physics teaching. One conclusion is that teachers’ and students’ lived experiences of formative assessment and rubric use need to be understood in relation to the wider context of their lifeworlds, which is marked by an increased focus on performance and results. This is crucial so that teachers and students would not be portrayed as the problems when investments in formative assessment do not meet expectations.
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| 2. |
- Aldridge, Jonathan, et al.
(författare)
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Blood PD-1+TFh and CTLA-4+CD4+ T cells predict remission after CTLA-4Ig treatment in early rheumatoid arthritis.
- 2022
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Ingår i: Rheumatology (Oxford, England). - : Oxford University Press (OUP). - 1462-0324 .- 1462-0332. ; 61:3, s. 1233-1242
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Tidskriftsartikel (refereegranskat)abstract
- Treatment with CTLA-4Ig blocks T cell activation and is clinically effective in rheumatoid arthritis (RA). However, it is unknown if specific CD4+ T cell subsets in blood at baseline predict remission after CTLA-4Ig, or other biological treatments with different modes of action, and how treatment affects CD4+ T cells in patients with untreated early RA (eRA).This study included 60 patients with untreated eRA from a larger randomised trial. They were treated with methotrexate combined with CTLA-4Ig (abatacept, n=17), anti-IL6 receptor (tocilizumab, n=21) or anti-TNF (certolizumab-pegol, n=22). Disease activity was assessed by clinical disease activity index (CDAI), DAS28, swollen joint counts, tender joint counts, CRP and ESR. The primary outcome was CDAI remission (CDAI≤2.8) at week 24. Proportions of 12 CD4+ T cell subsets were measured by flow cytometry at baseline and after 4, 12 and 24weeks of treatment.In patients treated with CTLA-4Ig, the proportions of PD-1+TFh and CTLA-4+ conventional CD4+ T cells at baseline predicted CDAI remission at week 24. CD4+ T cell subset proportions could not predict remission after treatment with anti-IL6R or anti-TNF. The percentage of regulatory T cells (Tregs) expressing CTLA-4 decreased in all treatment arms by 24weeks, but only CTLA-4Ig treatment significantly reduced the proportions of Tregs and PD-1+T follicular helper (TFh) cells.These findings indicate that circulating proportions PD-1+TFh and CTLA-4+ conventional CD4+ T cells at baseline may serve as predictive biomarkers for remission in early RA after CTLA-4Ig treatment.
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| 3. |
- Andersson, Catrin, et al.
(författare)
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Att organisera marknader : slutrapport från ett forskningsprogram
- 2015
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Forskningsprogrammet ”Att organisera marknader” har drivits vid Stockholms centrum för forskning om offentlig sektor (Score) och finansierats av Riksbankens Jubileumsfond. I denna bok redovisar vi några resultat från programmet. Boken bygger på ett stort antal böcker och artiklar vilka anges i slutet av boken. En fullständig förteckning av alla de publikationer som programmet hittills gett upphov till finns att tillgå på rj.se. Denna bok har flera författare förutom undertecknad: Susanna Alexius, Catrin Andersson, Patrik Aspers, Christina Garsten, Magnus Erlandsson, Kristoffer Strandqvist, Göran Sundström och Kristina Tamm Hallström. Samtliga är verksamma som forskare vid Score.
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| 4. |
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| 5. |
- Boström, Magnus, 1972-, et al.
(författare)
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Den dubbelbottnade frivilligheten
- 2004
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Ingår i: <em>Den organiserade frivilligheten</em>. - Lund : Liber. - 9147074221 ; , s. 190-209
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Boström, Magnus, 1972-, et al.
(författare)
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Global multi-stakeholder standard setters : how fragile are they?
- 2013
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Ingår i: Journal of Global Ethics. - : Informa UK Limited. - 1744-9626 .- 1744-9634. ; 9:1, s. 93-110
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Tidskriftsartikel (refereegranskat)abstract
- Worldwide we see the rise of new non-state, ‘multi-stakeholder’ organizations setting standardsfor socially and environmentally responsible practices. A multi-stakeholder organization builds on the idea of assembling actors from diverse societal spheres into one rule-setting process, thereby combining their resources, competences, and experiences. These processes also allow competing interests to negotiate and deliberate about their different concerns in globalpolitical and ethical matters. This paper analyzes multi-stakeholder dynamics within three global standard setters: the Forest Stewardship Council, the Marine Stewardship Council, andthe work of the International Organization for Standardization on social responsibility (ISO26000). Although the multi-stakeholder organizational form facilitates the establishment oftransnational non-state authority, this very structure could also result in fragility. The key aim of this paper is to elaborate on this fragility with specific focus on how participatoryaspects within a multi-stakeholder context both contribute to and destabilize the authority of the multi-stakeholder organization. The paper contributes theoretically to current discussionsabout transnational governance in the making, and more specifically it adds nuance to thediscussion about the fragility of non-state authority as well as a critical perspective to the literature on multi-stakeholder arrangements.
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| 7. |
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| 8. |
- Boström, Magnus, 1972-, et al.
(författare)
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NGO power in global social and environmental standard-setting
- 2010
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Ingår i: Global Environmental Politics. - : Massachusetts Institute of Technology Press (MIT Press): Arts & Humanities Titles etc. - 1526-3800 .- 1536-0091. ; 10:4, s. 36-59
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Tidskriftsartikel (refereegranskat)abstract
- We have seen a worldwide increase in new nonstate, multi-stakeholder organizations setting standards for socially and environmentally responsible behavior. These standard-setting arenas offer new channels for political participation for NGOs. Scholars have drawn attention to the rise and the role of NGOs in global politics, but there is less research on the power and long-term implications of NGO participation in transnational multi-stakeholder standard-setting. This article analyzes NGOs within three such global organizations: the Forest Stewardship Council, the Marine Stewardship Council, and the International Organization for Standardization on Social Responsibility. Using a power-based perspective, we demonstrate the impact that NGOs can have on multi-stakeholder work. In doing so, we analyze four types of NGO power: symbolic, cognitive, social, and monitoring power. The article further emphasizes institutional, structural, and discursive factors within multi-stakeholder organizations that create certain challenges to NGO power and participation in the longer term.
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| 9. |
- Boström, Magnus, 1972-, et al.
(författare)
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Organiserad frivillighet
- 2004
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Ingår i: Den organiserade frivilligheten. - Lund : Liber. - 9147074221 ; , s. 7-21
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Boström, Magnus, 1972-, et al.
(författare)
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Social sustainability requires social sustainability procedural prerequisites for reaching substantive goals
- 2015
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Ingår i: Nature and Culture. - : Berghahn Books. - 1558-6073 .- 1558-5468. ; 10:2, s. 131-156
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Tidskriftsartikel (refereegranskat)abstract
- The synergies and trade-offs between the various dimensions of sustainable development are attracting a rising scholarly attention. Departing from the scholarly debate, this article focuses on internal relationships within social sustainability. Our key claim is that it is diffi cult to strengthen substantive social sustainability goals unless there are key elements of social sustainability contained in the very procedures intended to work toward sustainability. Our analysis, informed by an organizing perspective, is based on a set of case studies on multi-stakeholder transnational sustainability projects (sustainability standards). This article explores six challenges related to the achievement of such procedures that can facilitate substantive social sustainability. Three of these concern the formulation of standards and policies, and three the implementation of standards and policies. To achieve substantive social sustainability procedures must be set in motion with abilities to take hold of people's concerns, frames, resources, as well as existing relevant institutions and infrastructures.
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| 11. |
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| 12. |
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| 13. |
- Edler, David, et al.
(författare)
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The expression of the novel CYP2W1 enzyme is an independent prognostic factor in colorectal cancer : a pilot study.
- 2009
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Ingår i: European Journal of Cancer. - : Elsevier BV. - 0959-8049 .- 1879-0852. ; 45:4, s. 705-712
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Tidskriftsartikel (refereegranskat)abstract
- AIM Cytochrome P450 (CYP) enzymes are important for drug metabolism. A novel cytochrome P450 enzyme, CYP2W1, has recently been identified. This enzyme is mainly found in foetal colon tissue and in tumour tissue. In this pilot study, we have investigated the expression of CYP2W1 in 162 tumours from patients with stages II and III colorectal cancer. METHODS The expression of CYP2W1 enzyme was immunohistochemically detected using a polyclonal antibody. Staining intensity was defined using a visual grading scale from 0 to 3. Grades 0-2 were classified as low, and grade 3 was classified as high expression of CYP2W1. RESULTS About 64% of the tumours expressed a low level of CYP2W1-expression, and 36% expressed a high level. CYP2W1-expression was an independent prognostic factor for overall survival (p=0.007), where a high expression was associated with a worse clinical outcome. CONCLUSIONS Immunohistochemically assessed expression of CYP2W1 is an independent prognostic factor in patients with stages II and III colorectal cancer.
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| 14. |
- Feldthusen, Caroline, 1977, et al.
(författare)
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The ASAS Health Index and Environmental Factors Item Set: validity and reliability of the Swedish translations in Swedish patients with ankylosing spondylitis
- 2024
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Ingår i: Scandinavian Journal of Rheumatology. - 0300-9742. ; 53:2, s. 104-111
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesTo translate the Assessment of SpondyloArthritis international Society (ASAS) Health Index (HI) Environmental Factors Item Set (EFIS) into Swedish and culturally adapt it for a Swedish context, and to assess the construct validity of the Swedish version of the ASAS HI and test-retest reliability in ASAS HI and EFIS in Swedish patients with ankylosing spondylitis (AS).MethodTranslation and cross-cultural adaptation of the EFIS were carried out according to a forward-backward procedure consisting of five steps. The construct validity of the ASAS HI was tested using Spearman correlation with standard health outcomes for axial spondyloarthritis (axSpA). Reliability was analysed by internal consistency with the Cronbach's alpha coefficient for ASAS HI, and test-retest reliability with intraclass correlation coefficients (ICCs) for ASAS HI and kappa agreement for the individual items of EFIS.ResultsThe translation of EFIS showed acceptable face and content validity. ASAS HI showed an acceptable internal consistency (Cronbach's alpha 0.79), and excellent test-retest reliability (ICC 0.87). Test-retest reliability for EFIS showed varied results, with kappa agreement for the individual items ranging from poor (-0.027) to good (0.80).ConclusionsThe Swedish version of ASAS HI proved to be valid and reliable and is recommended for assessing the impact of AS on global functioning and health. A Swedish version of EFIS has been produced and uploaded on the ASAS website. The EFIS proved to have acceptable face and content validity, and may contribute to the contextual interpretation of the ASAS HI.
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| 15. |
- Hallström, Henrik, et al.
(författare)
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Matriser, krafter och fysik : Elevers levda erfarenheter av bedömningsmatriser i grundskolans fysikundervisning
- 2024
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Ingår i: NorDiNa. - : University of Oslo Library. - 1504-4556 .- 1894-1257. ; 20:1, s. 72-85
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decade, the use of rubrics for formative purposes in science education has attracted at-tention for its potential to positively influence students’ self-regulation and learning. This study explores students’ lived experiences of using rubrics as part of learning about the concept of force in the physics classroom. To address these experiences, 19 compulsory school students were interviewed about their use of a rubric specifically designed for an assignment on force and motion. Three main themes emerged from an analysis of the descriptions of their lived experiences: (i) rubrics provide a sense of control; (ii) rubrics are required for high grades, but create stress; and (iii) rubrics foster strategic learning. The experiences revealed in these themes have the potential to deepen our understanding of the challenges involved in using rubrics to teach physics and have implications for teaching students about force
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| 16. |
- Hallström, Henrik, et al.
(författare)
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Matriser, krafter och fysik: Elevers levda erfarenheter av bedömningsmatriser i grundskolans fysikundervisning : Rubrics, forces and physics: Students’ lived experiences of assessment rubrics in compulsory physics teaching
- 2024
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Ingår i: Nordic Studies in Science Education. - 1504-4556 .- 1894-1257. ; 20:1, s. 72-85
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decade, the use of rubrics for formative purposes in science education has attracted attention for its potential to positively influence students' self-regulation and learning. This study explores students' lived experiences of using rubrics as part of learning about the concept of force in the physics classroom. To address these experiences, 19 compulsory school students were interviewed about their use of a rubric specifically designed for an assignment on force and motion. Three main themes emerged from an analysis of the descriptions of their lived experiences: (i) rubrics provide a sense of control; (ii) rubrics are required for high grades, but create stress; and (iii) rubrics foster strategic learning. The experiences revealed in these themes have the potential to deepen our understanding of the challenges involved in using rubrics to teach physics and have implications for teaching students about force.
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| 17. |
- Hallström, Jonas, 1969-, et al.
(författare)
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Avslutning
- 2013. - 1
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Ingår i: Teknik som kunskapsinnehåll i svensk skola 1842-2010. - Hedemora : Gidlunds förlag. - 9789178448630 ; , s. 251-255
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Teknikens kunskapshistoria är för många en historia om svenska uppfinnare, tillämpad naturvetenskap och ingenjörsutbildning. I den här antologin riktas istället blicken mot de bredare lagren av samhället, mot folkskola, grundskola och yrkesskolor och det tekniska kunskapsinnehåll som behandlats där. Hur har man sett på den tekniska kunskapens roll i dessa utbildningsformer och hur har den förändrats?I boken presenteras forskning om det tekniska kunskapsinnehållet i svensk skola mellan 1842 och 2010 både i form av spridda inslag av teknikinnehåll och som ett ämne med namnet Teknik. Några återkommande mönster i denna utveckling identifieras, vilka alla på ett eller annat sätt kan sägas ha varit styrande för hur aktörer har besvarat grundläggande frågor om teknikinnehållet i skolan under undersökningsperioden. Frågorna har rört motiven för teknisk kunskap och vilken typ av teknik som är viktigast, men också dess gränser, utseende och upptagningsområde.
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| 18. |
- Hallström, Jonas, et al.
(författare)
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Avslutning
- 2013
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Ingår i: Teknik som kunskapsinnehåll i svensk skola 1842-2010. - : Gidlunds förlag. - 9789178448630 ; , s. 251-255
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 19. |
- Hallström, Jonas, 1969-, et al.
(författare)
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Inledning : Perspektiv på teknik i skolan, 1842-2010
- 2013. - 1
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Ingår i: Teknik som kunskapsinnehåll i svensk skola 1842-2010. - Hedemora : Gidlunds förlag. - 9789178448630 ; , s. 9-18
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Teknikens kunskapshistoria är för många en historia om svenska uppfinnare, tillämpad naturvetenskap och ingenjörsutbildning. I den här antologin riktas istället blicken mot de bredare lagren av samhället, mot folkskola, grundskola och yrkesskolor och det tekniska kunskapsinnehåll som behandlats där. Hur har man sett på den tekniska kunskapens roll i dessa utbildningsformer och hur har den förändrats?I boken presenteras forskning om det tekniska kunskapsinnehållet i svensk skola mellan 1842 och 2010 både i form av spridda inslag av teknikinnehåll och som ett ämne med namnet Teknik. Några återkommande mönster i denna utveckling identifieras, vilka alla på ett eller annat sätt kan sägas ha varit styrande för hur aktörer har besvarat grundläggande frågor om teknikinnehållet i skolan under undersökningsperioden. Frågorna har rört motiven för teknisk kunskap och vilken typ av teknik som är viktigast, men också dess gränser, utseende och upptagningsområde.
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| 20. |
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| 21. |
- Hallström, Jonas, 1969-, et al.
(författare)
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Teknik i fritidshem – mellan omsorg och utbildning
- 2018
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Ingår i: Teknikdidaktisk forskning för lärare. - Norrköping : NATDID, Nationellt centrum för naturvetenskapernas och teknikens didaktik. - 9789176853269 ; , s. 41-50
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- En stor andel svenska barn mellan sex och nio år gamla går efter skolan till ”fritids”. Fritidshem kännetecknas av både utbildning och omsorg, och därmed av både formella och informella aktiviteter. På senare år har verksamheten blivit mer och mer influerad av skolan och numera finns ett eget kapitel för fritidshem i den nationella läroplanen för grundskolan. Fritidshemmen genomgår därför en förändring som kommer att medföra att mer formella aktiviteter införs, exempelvis inom teknik, samtidigt som praktiskt taget ingen forskning har gjorts på detta. Syftet med det här kapitlet är att presentera några resultat från en pågående forskningsstudie om teknikens roll i aktiviteter på fritidshem. Observationerna fokuserade på de dagliga aktiviteterna på fritidshemmen där teknik hade en central roll. Vi använder begreppet gränsobjekt för att analysera teknik i aktiviteterna. Resultaten visar att det är en speciell sorts teknikundervisning som uppstår i fritidshem, på gränsen mellan den informella och formella verksamheten: från det informella lekrelaterade byggandet med Lego och träklotsar till den mer formella datorundervisningen. I dessa aktiviteter finns ett tydligt fritidsinslag, framför allt i form av ett fritt val av teknik och vad man vill lära sig. Det faktum att barn kan välja fritt pekar inte bara på att teknik i fritidshem är ett gränsobjekt med en stor tolkningsflexibilitet, utan också att teknikundervisning i fritidshem skulle kunna vara en lustfylld och effektiv väg till teknisk allmänbildning.
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| 22. |
- Hallström, Jonas, 1969-, et al.
(författare)
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Teknikens och naturvetenskapernas didaktik
- 2020
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Ingår i: Ämnesdidaktik vid Linköpings universitet. - Linköping : Linköping University Electronic Press. ; , s. 34-39
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 23. |
- Hallström, Jonas, 1969-, et al.
(författare)
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The study of technology as a field of knowledge in general education : historical insights and methodological considerations from a Swedish case study, 1842-2010
- 2014
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Ingår i: International journal of technology and design education. - : Springer Science and Business Media LLC. - 0957-7572 .- 1573-1804. ; 24:2, s. 121-139
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Tidskriftsartikel (refereegranskat)abstract
- Today, technology education in Sweden is both a high-status and a low-status phenomenon. Positive values such as economic growth, global competitiveness and the sustainability of the welfare state are often coupled with higher engineering education and sometimes even upper secondary education. Negative values, on the other hand, are often associated with primary and lower secondary education in this subject. Within the realm of technology education at such lower levels of schooling in Sweden, different actors have often called for reformed curricula or better teacher training, owing to the allegedly poor state of technology education in schools. Recurring demands for a change in technology education are nothing unique from an historical point of view, however. In fact, the urge to influence teaching and learning in technology is much older than the school subject itself. The aim of this article is to describe and analyse some key patterns in technology education in Swedish elementary and compulsory schools from 1842 to 2010. This study thus deals with how technological content has developed over time in these school forms as well as how different actors in and outside the school have dealt with the broader societal view of what is considered as important knowledge in technology as well as what kind of technology has particular significance. The long period of investigation from 1842 to 2010 as well as a double focus on technology as scattered educational content and a subject called Technology make it possible to identify recurring patterns, which we have divided into three overarching themes: Technological literacy and the democratic potential of technological knowledge, The relationship between school technology and higher forms of technology education and The relationship between technology and science.
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| 24. |
- Hallström, Magnus, et al.
(författare)
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Physical function and sex differences in radiographic axial spondyloarthritis: a cross-sectional analysis on Bath Ankylosing Spondylitis Functional Index
- 2023
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Ingår i: Arthritis Research and Therapy. - : BioMed Central (BMC). - 1478-6354 .- 1478-6362. ; 25:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Physical function is an important determinant of health-related quality of life in radiographic axial spondyloarthritis patients (r-axSpA). To improve the basis of effective healthcare efforts, we aimed to investigate which demographic and disease-related factors that influence Bath Ankylosing Spondylitis Functional Index (BASFI) in r-axSpA patients overall and stratified by sex. Furthermore, we sought to explore differences between sexes regarding separate BASFI questions and also to explore which factors that may contribute to these differences. Methods: This observational cross-sectional study included patients fulfilling the modified New York criteria for Ankylosing Spondylitis. Patients were assessed with 66/68 joint count and Bath Ankylosing Spondylitis Metrology Index (BASMI) measurements. Lateral X-rays were performed for Modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS)-C-Reactive Protein (CRP), and BASFI were registered. Multivariable linear regression analyses were used to investigate which factors that associate with BASFI. Results: A total of 353 r-axSpA patients were included, mean age 52.2 ± 12.7years, 62.3% males. No significant sex difference was seen in BASFI scores (2.7 ± 2.0 in males vs 2.9 ± 2.1 in females). Age, body mass index, ASDAS-CRP, BASMI or mSASSS, fatigue, and tenderness were found to associate independently with BASFI in different models (R 2 0.53–0.63). Investigation of separate BASFI questions revealed that the ability to look over shoulder was worse in males than females (mean 4.43 ± 3.37 vs 3.74 ± 3.06, p = 0.05) and most strongly correlated with mSASSS and BASMI among separate BASFI questions (r = 0.53, p < 0.001; r = 0.62, p < 0.001). The ability to climb stairs was worse in females than males (mean 2.49 ± 2.77 vs 1.54 ± 2.32, p < 0.001). Conclusions: No difference between male and female r-axSpA patients was seen in BASFI despite significant sex differences in BASMI, mSASSS, and CRP levels. Our results underline the impact of fatigue and tenderness on BASFI. The ability to climb stairs without a handrail was scored worse among females compared to males. Furthermore, the ability to look over the shoulder was worse in males than females and closely related to spinal mobility and structural spinal changes.
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| 25. |
- Hallström, Sara, et al.
(författare)
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Risk factors and incidence over time for lower extremity amputations in people with type 1 diabetes: an observational cohort study of 46,088 patients from the Swedish National Diabetes Registry
- 2021
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 64, s. 2751-2761
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis The aim of this work was to study the incidence over time of lower extremity amputations and determine variables associated with increased risk of amputations in people with type 1 diabetes. Methods Individuals with type 1 diabetes registered in the Swedish National Diabetes Registry with no previous amputation from 1 January 1998 and followed to 2 October 2019 were included. Time-updated Cox regression and gradient of risk per SD were used to evaluate the impact of risk factors on the incidence of amputation. Age- and sex-adjusted incidences were estimated over time. Results Of 46,088 people with type 1 diabetes with no previous amputation (mean age 32.5 years [SD 14.5], 25,354 [55%] male sex), 1519 (3.3%) underwent amputation. Median follow-up was 12.4 years. The standardised incidence for any amputation in 1998-2001 was 2.84 (95% CI 2.32, 3.36) per 1000 person-years and decreased to 1.64 (95% CI 1.38, 1.90) per 1000 person-years in 2017-2019. The incidence for minor and major amputations showed a similar pattern. Hyperglycaemia and renal dysfunction were the strongest risk factors for amputation, followed by older age, male sex, cardiovascular comorbidities, smoking and hypertension. Glycaemic control and age- and sex-adjusted renal function improved during the corresponding time period as amputations decreased. Conclusions/interpretation The incidence of amputation and of the most prominent risk factors for amputation, including renal dysfunction and hyperglycaemia, has improved considerably during recent years for people with type 1 diabetes. This finding has important implications for quality of life, health economics and prognosis regarding CVD, indicating a trend shift in the treatment of type 1 diabetes.
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| 26. |
- Hallström, Sara, et al.
(författare)
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Risk factors, mortality trends and cardiovasuclar diseases in people with Type 1 diabetes and controls: A Swedish observational cohort study
- 2022
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Ingår i: Lancet Regional Health-Europe. - : Elsevier BV. - 2666-7762. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Background Historically, the incidence of cardiovascular disease and mortality in persons with Type I diabetes (TID) has been increased compared to the general population. Contemporary studies on time trends of mortality and cardiovascular disease are sparse. Methods In this observational study, TID persons were identified in the Swedish National Diabetes Registry (n=45,575) and compared with matched controls from the general population (n=220,141). Incidence rates from 2002 to 2019 were estimated with respect to mortality and cardiovascular disease in persons with TID overall and when stratified for prevalent cardiovascular and renal disease relative to controls. Findings Mean age in persons with TID was 32.4 years and 44.9% (20,446/45,575) were women. Age- and sex-adjusted mortality rates declined over time in both groups but remained significantly higher in those with TID compared to controls during 2017-2019, 7.62 (95% CI 7.16; 8.08) vs. 2.23 (95% CI 2.13; 2.33) deaths per 1,000 person years. Myocardial infarction, heart failure and stroke decreased over time in both groups, with persistent excess risks in the range of 3.4 -5.0 times from 2017 to 2019 in those with TID. TID persons >= 45 years without previous renal or cardiovascular complications had standardized mortality rates similar or even lower than controls 5.55 (4.51; 6.60) vs.7.08 (6.75; 7.40) respectively in the last time period. Interpretation Excess mortality persisted over time in persons with TID, largely in patients with cardiorenal complications. Improved secondary prevention with a focus on individualized treatment is needed to dose the gap in mortality for individuals with TID.
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| 27. |
- Hultén, Magnus, 1970-, et al.
(författare)
-
Inledning : Tema: "Skolans digitalisering"
- 2019
-
Ingår i: Vägval i skolans historia. - Stockholm : Föreningen för svensk undervisningshistoria. - 2002-0147. ; :1
-
Tidskriftsartikel (populärvet., debatt m.m.)
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| 28. |
- Isaksson, Sofia Sterner, et al.
(författare)
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Discordance between mean glucose and time in range in relation to HbA1c in individuals with type 1 diabetes: results from the GOLD and SILVER trials
- 2024
-
Ingår i: DIABETOLOGIA. - : SPRINGER. - 0012-186X .- 1432-0428.
-
Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis Previous studies have shown that individuals with similar mean glucose levels (MG) or percentage of time in range (TIR) may have different HbA(1c) values. The aim of this study was to further elucidate how MG and TIR are associated with HbA(1c). Methods Data from the randomised clinical GOLD trial (n=144) and the follow-up SILVER trial (n=98) of adults with type 1 diabetes followed for 2.5 years were analysed. A total of 596 paired HbA(1c)/continuous glucose monitoring measurements were included. Linear mixed-effects models were used to account for intra-individual correlations in repeated-measures data. Results In the GOLD trial, the mean age of the participants (+/- SD) was 44 +/- 13 years, 63 (44%) were female, and the mean HbA(1c) (+/- SD) was 72 +/- 9.8 mmol/mol (8.7 +/- 0.9%). When correlating MG with HbA(1c), MG explained 63% of the variation in HbA(1c) (r=0.79, p<0.001). The variation in HbA(1c) explained by MG increased to 88% (r=0.94, p value for improvement of fit <0.001) when accounting for person-to-person variation in the MG-HbA(1c) relationship. Time below range (TBR; <3.9 mmol/l), time above range (TAR) level 2 (>13.9 mmol/l) and glycaemic variability had little or no effect on the association. For a given MG and TIR, the HbA(1c) of 10% of individuals deviated by >8 mmol/mol (0.8%) from their estimated HbA(1c) based on the overall association between MG and TIR with HbA(1c). TBR and TAR level 2 significantly influenced the association between TIR and HbA(1c). At a given TIR, each 1% increase in TBR was related to a 0.6 mmol/mol lower HbA(1c) (95% CI 0.4, 0.9; p<0.001), and each 2% increase in TAR level 2 was related to a 0.4 mmol/mol higher HbA(1c) (95% CI 0.1, 0.6; p=0.003). However, neither TIR, TBR nor TAR level 2 were significantly associated with HbA(1c) when accounting for MG. Conclusions/interpretation Inter-individual variations exist between MG and HbA(1c), as well as between TIR and HbA(1c), with clinically important deviations in relatively large groups of individuals with type 1 diabetes. These results may provide important information to both healthcare providers and individuals with diabetes in terms of prognosis and when making diabetes management decisions.
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| 29. |
- Jansson, Magnus, et al.
(författare)
-
Technology Education and Informal Learning : Technology in the Swedish Leisure-Time Centre as Boundary Object
- 2016
-
Ingår i: <em>PATT-32 Proceedings: Technology Education for 21st Century Skills</em>. - Utrecht : University of Applied Sciences. ; , s. 226-233
-
Konferensbidrag (refereegranskat)abstract
- A majority of Swedish children between six and nine years old attend afterschool activities in a leisure-time centre, fritidshem, until their parents finish work for the day. Leisure-time centres are characterised by “educare” activities, that is, both educational and carerelated activities and thus both formal and informal learning settings. The centres are part of the Swedish educational system and activities should be related to the national curriculum for the compulsory school. The centres are right now in an interesting transition which will lead to the introduction of more formal learning activities, for instance, in technology, at the same time as virtually no research has been carried out on technology activities in the centres. The aim of this paper is therefore to study the role of technology in activities in leisure-time centres. The results are drawn from field work conducted in three Swedish leisure-time centres. The observations focused upon the daily activities in the leisure centres, specifically activities where technology play a central part. The data collection was completed with interviews with teachers. We use the concept of boundary object to analyse the technological activities. The findings indicate that there is a special technology education that emerges in the context of the leisuretime center – leisure-time technology education – at the intersection between informal and formal technology learning, which ranges from the informal play-related construction of Lego and wooden blocks to the more formal computer instruction. The amorphousness of leisure-time technology – the fact that children can choose what they want it to be and what to learn –points to it being a boundary object with a very open interpretative flexibility.
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| 30. |
- Jansson, Magnus, 1962-
(författare)
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Vardagliga teknikaktiviteter i fritidshem : organisation, didaktik och görande
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Det övergripande syftet med denna licentiatstudie är att undersöka hur teknik som undervisningsområde kommer till uttryck inom fritidsverksamheter. Syftet inrymmer ett fokus på vad fritidslärarna gör för att organisera undervisning. Studien utgår ifrån följande frågeställningar: hur ser fritidslärarna på undervisning i teknik i fritidshem; och hur organiseras teknik som en del av undervisnings-praktiken i fritidshem? Studien är kvalitativ samt inspirerad av etnografi och Grounded theory. Studiens teoretiska perspektiv är symbolisk interaktionism, samt Mitchams modell för manifestation av teknik från 1994. Studien är en fält-studie på tre olika fritidshem. I studiens bakgrundsbeskrivning påvisas att fritidshem har haft en historia där hantverk och olika estetiska aktiviteter varit vanligt förekommande aktiviteter. Fritidshemmen har också, i och med en tydligare styrning kring lärandet, fått del i läroplanen Lgr11 (reviderad 2016), där tekniken är en framskriven del av undervisningen. Studien handlar därför om hur fritidshemspersonalen reflekterar och förhandlar och definierar för att göra olika teknikaktiviteter. Fritidshemspersonalen gör, enligt studien, här en nyorientering för att tolka innehållet i den egna läroplansdelen. I denna nyorientering använder fritidshemspersonalen sig av tre olika strategier för att hantera detta med teknik som undervisning, detta i ett gränsland mellan tidigare idétraditioner och en utökad styrning.
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| 31. |
- Kristensson Hallström, Inger, et al.
(författare)
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eHealth as an Aid for Facilitating and Supporting Self-Management in Families with Long-Term Childhood Illness; Development, Evaluation, and Implementation in Clinical Practice
- 2023
-
Ingår i: Clinical Health Promotion - Research and Best Practice for patients, staff and community. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction eHealth, defined by WHO as: “the transfer of health resources and healthcare by electronic means” are expected to increase communication between healthcare providers and patients and increase accessibility and patient participation in healthcare. The aim of this research programme is to: 1) develop a sustainable multidisciplinary environment for advancing, evaluating, and implementing models of eHealth to promote self-management for children and their families, and 2) increase the present knowledge of clinical and economic cost-effectiveness of eHealth as an aid for supporting self-management in families with long-term childhood illness. Method The research is performed in Sweden, Denmark, and Ethiopia and organized in three research domains: eHealth to enable and promote self-management in advanced paediatric care, eHealth for early diagnosis and treatment in paediatric care, and Co-Creation of multidisciplinary knowledge for the translation of eHealth in practice. The research follows a framework for developing and evaluating complex interventions in healthcare. Through participatory design family members and care providers participate throughout the research process. Quantitative and qualitative data as well as health economics are collected in six clinical areas. Five general areas are run transversal. Results and conclusion Evidence-based best practices in developing and evaluating eHealth in paediatric healthcare will be suggested. As implementation is part of the programme, cost-effective eHealth directly benefiting families and healthcare services will be guaranteed.
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| 32. |
- Levinsson, Magnus, et al.
(författare)
-
Problems in developing formative assessment : A physics teacher's lived experiences of putting the ideas into practice
- 2013
-
Ingår i: Assessment Matters. - 1176-7839 .- 2230-617X. ; 5, s. 116-142
-
Tidskriftsartikel (refereegranskat)abstract
- In Sweden, systematic reviews have prompted a strong government focus on implementing formative assessment in science and mathematics education. However, the intention behind this investment—to improve Sweden’s position in TIMSS and PISA—appears to overlook the difficulty of putting research into practice. The purpose of this study is to explore the problems associated with incorporating formative assessment into classroom work by focusing on the experiences of a physics teacher who participated in a local development project in an upper secondary school in Sweden. The case study is based on a phenomenological approach which emphasises collaboration between researcher and participant, and five different themes of lived experience are described as a result of joint interpretations: (1) resistance from the students; (2) stuck in formal teacher roles; (3) sacrifices to bring about change; (4) avoiding risks in the classroom; and (5) worries about the opinion of others. These lived-through dimensions deepen our understanding of the barriers which some teachers face and carry implications for the support they need. Finally, this article points out the challenge for the systematic review movement in Sweden, and elsewhere, to incorporate and communicate the different strands of research on formative assessment.
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| 33. |
- Levinsson, Magnus, 1977, et al.
(författare)
-
Problems in developing formative assessment: A physics teacher’s lived experiences of putting the ideas into practice
- 2013
-
Ingår i: Assessment Matters. - : NZCER Press, New Zealand Council for Educational Research. - 1176-7839 .- 2230-617X. ; :5, s. 116-142
-
Tidskriftsartikel (refereegranskat)abstract
- In Sweden, systematic reviews have prompted a strong government focus on implementing formative assessment in science and mathematics education. However, the intention behind this investment—to improve Sweden’s position in TIMSS and PISA—appears to overlook the difficulty of putting research into practice. The purpose of this study is to explore the problems associated with incorporating formative assessment into classroom work by focusing on the experiences of a physics teacher who participated in a local development project in an upper secondary school in Sweden. The case study is based on a phenomenological approach which emphasises collaboration between researcher and participant, and five different themes of lived experience are described as a result of joint interpretations: (1) resistance from the students; (2) stuck in formal teacher roles; (3) sacrifices to bring about change; (4) avoiding risks in the classroom; and (5) worries about the opinion of others. These lived-through dimensions deepen our understanding of the barriers which some teachers face and carry implications for the support they need. Finally, this article points out the challenge for the systematic review movement in Sweden, and elsewhere, to incorporate and communicate the different strands of research on formative assessment.
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| 34. |
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| 35. |
- Lundqvist, Magnus, et al.
(författare)
-
Solid-phase cloning for high-throughput assembly of single and multiple DNA parts
- 2015
-
Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 43:7
-
Tidskriftsartikel (refereegranskat)abstract
- We describe solid-phase cloning (SPC) for high-throughput assembly of expression plasmids. Our method allows PCR products to be put directly into a liquid handler for capture and purification using paramagnetic streptavidin beads and conversion into constructs by subsequent cloning reactions. We present a robust automated protocol for restriction enzyme based SPC and its performance for the cloning of >60 000 unique human gene fragments into expression vectors. In addition, we report on SPC-based single-strand assembly for applications where exact control of the sequence between fragments is needed or where multiple inserts are to be assembled. In this approach, the solid support allows for head-to-tail assembly of DNA fragments based on hybridization and polymerase fill-in. The usefulness of head-to-tail SPC was demonstrated by assembly of >150 constructs with up to four DNA parts at an average success rate above 80%. We report on several applications for SPC and we suggest it to be particularly suitable for high-throughput efforts using laboratory workstations.
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| 36. |
- Oddy, Carolyn, 1994, et al.
(författare)
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A framework for macroscale modelling of inelastic deformations in 3D-woven composites
- 2021
-
Ingår i: Mechanics of Materials. - : Elsevier BV. - 0167-6636 .- 1872-7743. ; 160
-
Tidskriftsartikel (refereegranskat)abstract
- The use of 3D-woven composite materials has shown promising results. Along with weight-efficient stiffness and strength, they have demonstrated encouraging out of plane properties, damage tolerance and energy absorption capabilities. The widespread adoption of 3D-woven composites in industry however, requires the development of efficient computational models that can capture the material behaviour. The following work proposes a framework for modelling the mechanical response of 3D-woven composites on the macroscale. This flexible and thermodynamically consistent framework, decomposes the stress and strain tensors into two main parts motivated by the material architecture. The first is governed by the material behaviour along the reinforcement directions while the second is driven by shear behaviours. This division allows for the straightforward addition and modification of various inelastic phenomena observed in 3D-woven composites. In order to demonstrate the applicability of the framework, focus is given to predicting the material response of a 3D glass fibre reinforced epoxy composite. Prominent non-linearities are noted under shear loading and loading along the horizontal weft yarns. The behaviour under tensile loading along the weft yarns is captured using a Norton style viscoelasticity model. The non-linear shear response is introduced using a crystal plasticity inspired approach. Specifically, viscoelasticity is driven on localised slip planes defined by the material architecture. The viscous parameters are calibrated against experimental results and off axis tensile tests are used to validate the model.
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| 37. |
- Oddy, Carolyn, 1994, et al.
(författare)
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Evaluation of damage initiation models for 3D-woven fibre composites
- 2019
-
Ingår i: ECCM 2018 - 18th European Conference on Composite Materials. - : Applied Mechanics Laboratory.
-
Konferensbidrag (refereegranskat)abstract
- Three dimensional (3D) fibre-reinforced composites have shown weight efficient strength and stiffness characteristics as well as promising energy absorption capabilities. In the considered class of 3D-reinforcement, vertical and horizontal weft yarns interlace warp yarns. The through-thickness reinforcements suppress delamination and allow for stable and progressive damage growth in a quasi-ductile manner. With the ultimate goal of developing a homogenised computational model to predict how the material will deform and eventually fail under loading, this work proposes candidates for failure initiation criteria. The criteria are evaluated numerically for tensile, compressive and shear tests. The extension of the LaRC05 stress based failure criteria to this class of 3D-woven composites is one possibility. This however, presents a number of challenges which are discussed. These challenges are related to the relative high stiffness in all directions, which produce excessively high shear components when projected onto potential off-axis failure planes. To circumvent these challenges, strain based criteria inspired by LaRC05 are formulated. Results show that strain based failure predictions for the simulated load cases are qualitatively more reasonable.
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| 38. |
- Oddy, Carolyn, 1994, et al.
(författare)
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Predicting damage initiation in 3D fibre-reinforced composites – The case for strain-based criteria
- 2019
-
Ingår i: Composite structures. - : Elsevier Ltd. - 0263-8223 .- 1879-1085. ; 230
-
Tidskriftsartikel (refereegranskat)abstract
- Three dimensional (3D) fibre-reinforced composites have shown weight efficient strength and stiffness characteristics as well as promising energy absorption capabilities. In the considered class of 3D-reinforcement, vertical and horizontal weft yarns interlace warp yarns. The through-thickness reinforcements suppress delamination and allow for stable and progressive damage growth in a quasi-ductile manner. With the ultimate goal of developing a homogenised computational model to predict how the material will deform and eventually fail under loading, this work proposes candidates for failure initiation criteria. It is shown that the extension of the LaRC05 stress-based failure criteria for unidirectional laminated composites, to this class of 3D-reinforced composite presents a number of challenges and leads to erroneous predictions. Analysing a mesoscale representative volume element does however indicate, that loading the 3D fibre-reinforced composite produces relatively uniform strain fields. The average strain fields of each material constituent are well predicted by an equivalent homogeneous material response. Strain based criteria inspired by LaRC05 are therefore proposed. The criteria are evaluated numerically for tensile, compressive and shear tests. Results show that their predictions for the simulated load cases are qualitatively more reasonable.
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| 39. |
- Pandya, Jayesh M., et al.
(författare)
-
Circulating T helper and T regulatory subsets in untreated early rheumatoid arthritis and healthy control subjects
- 2016
-
Ingår i: Journal of Leukocyte Biology. - 0741-5400. ; 100:4, s. 823-833
-
Tidskriftsartikel (refereegranskat)abstract
- The pathogenic role and frequency of T cell subtypes in early rheumatoid arthritis are still unclear. We therefore performed a comprehensive analysis of the circulating T cell subtype pattern in patients with untreated early rheumatoid arthritis compared to healthy control subjects. Peripheral bloodmononuclear cells were obtained from 26 patients with untreated early rheumatoid arthritis and from with 18 age-and sex-matched healthy control subjects. T helper cell types Th0, Th1, Th2, Th17, and Th1/17 and nonclassic T helper subsets were defined by flow cytometry based on the expression of chemokine receptors CCR4, CCR6, and CXCR3. Regulatory T cells were defined by expression of CD25(+) CD127(low) and also FOXP3. CXCR5(+) cells among regulatory and nonregulatory T cells were defined as T follicular regulatory and T follicular helper cells, respectively. The phenotype of T cell subsets was confirmed by transcription factor and cytokine secretion analyses. Multivariate discriminant analysis showed that patients with untreated early rheumatoid arthritis were segregated from healthy control subjects based on the circulating T cell subset profile. Among the discriminator subsets, CCR4(+)CXCR3(-) (Th2 and Th17), CTLA4(+) and FOXP3(+) subsets were present in significantly higher frequencies, whereas CCR42 (Th1/Th17, CCR6(+)CCR4(-) CXCR3(-), and Th1) subsets were present in lower frequencies in patients with untreated early rheumatoid arthritis compared with healthy control subjects. The proportions of Th2 and Th17 subsets associated positively with each other and negatively with the CXCR3(+)/interferon gamma-secreting subsets (Th1 and Th1/Th17) in patients with untreated rheumatoid arthritis. The proportions of Th2 cells increased with age in patients with untreated early rheumatoid arthritis and healthy control subjects. The dominance of circulating CCR4(+) CXCR3(-) T helper subsets (Th2 and Th17) in untreated early rheumatoid arthritis point toward a pathogenic role of these cells in early stages of the disease.
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| 40. |
- Rajput, Moeen S, et al.
(författare)
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Compression of structural foam materials : Experimental and numerical assessment of test procedure and specimen size effects
- 2017
-
Ingår i: Journal of Sandwich Structures and Materials. - : Sage Publications. - 1099-6362 .- 1530-7972.
-
Tidskriftsartikel (refereegranskat)abstract
- This study was initiated based on the observation that standardized test for flatwise compression of foam materials, give significantly different test results for the measured moduli, and that these standards to date lack adequate instructions on how the strain should be measured and what specimen size should be used. A brief review of previous work shows that existing test methodologies provide significantly different results for the compressive moduli of foams depending on how the strains are measured. A thorough experimental study of the out-of-plane compressive properties is conducted on three different closed-cell foam materials, where strains measured with two different extensometer placements, and with digital image correlation, come out significantly differently. A parametric study is also performed showing that the results vary considerably with in-plane specimen dimensions, indicating effects of finite size and localized strain at edges. Both stochastic amorphous and homogenized finite element models of foam back the experimental observations by illustrating the effects of finite size and various boundary conditions on the measured properties.
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| 41. |
- Rajput, Moeen S., et al.
(författare)
-
Design and evaluation of a novel instrumented drop-weight rig for controlled impact testing of polymer composites
- 2018
-
Ingår i: Polymer testing. - : Elsevier. - 0142-9418 .- 1873-2348. ; 68, s. 446-455
-
Tidskriftsartikel (refereegranskat)abstract
- A drop-weight rig (DWR) intended to test the true impact response of laminated compositematerials is presented. The test setup is designed to prevent the transfer of unwanted mechanical noise, e.g. vibrations, into the load cell that is used to measure the load during the impact event. A novel catch mechanism preventing secondary impact is also implemented in the DWR design. A detailed evaluation is performed both in terms of the experimental modal and uncertainty analysis of the measured results from the DWR. The results demonstrate that the rig is capable of capturing the true impact response, providing highly resolved and noise-free force-time measurements where even subtle details of the impact event are visible. The rig also enables impact testing with good repeatability.
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| 42. |
- Rajput, Moeen S, et al.
(författare)
-
Distinguishing between strain measurement procedures during compressive testing of foam materials
- 2015
-
Ingår i: 20th International Conference on Composite Materials, ICCM 2015. - : Aalborg Universitetsforlag.
-
Konferensbidrag (refereegranskat)abstract
- The out-of-plane compressive properties of foam materials are essential for their performance as core material in sandwich structures. Accurate data for these properties are crucial for modeling and analysis of impact response and critical design assessment of e.g. sandwich structures. Current standards differ in specifying how the strains should be measured. When different standard methods are used, significant differences in test results for flatwise compression are obtained. An experimental study of the out-of-plane compressive properties (strength and modulus) of foam materials is conducted, where two types of foams are studied; Rohacell 200 Hero and Divinycell H60. Both are closed cell structured foams used for cores in sandwich materials. A review of established test methodologies is conducted and the test results show that there is a significant difference in strain values measured from the cross head displacement (termed "gross core strain") and when extensometer directly applied onto the foam (termed "net core strain"). The results are not related to the compliance of the test rig, which is another issue outside the scope of this investigation. The effect of surface priming on the compressive behavior is further investigated followed by digital image correlation (DIC) for detailed recordings of the strain fields.
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| 43. |
- Rajput, Moeen S., et al.
(författare)
-
Evaluation of test methods and face-sheet thickness effects in damage tolerance assessment of composite sandwich plates
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Composite sandwich materials are used in load-carrying components in commercial aircraft due to their lightweight characteristics and high strength-to-weight ratio. However, composite structures are vulnerable to impact damage which can drastically reduce their load-bearing capability. Consequently, damage tolerance assessment of composite sandwich structures is of utmost importance. At present, there is a lack of standardised test methods for such assessments of sandwich structures. This study compared test methods for damage tolerance by means of compression after impact (CAI) and how the residual strength varied with face-sheet thickness. Three different test methods, including two types of CAI, were used i.e. CAI-single skin (CAI-SS) and CAI-sandwich (CAI-SW), and one four-point bending-after-impact (BAI) test method was used for residual strength measurement. A thorough experimental campaign was performed on different face-sheet configurations utilising both symmetric and asymmetric sandwich panels. Test specimens were subjected to impact energy levels causing barely visible damage. Then they were tested using the different methods and the differences in the results were highlighted. In all three test methods, the specimens failed in compression showing prominent fibre fracture and delamination. This compressive failure was initiated at the impact zone and grew across the width of the specimen, perpendicular to the loading direction. The CAI-SW test method showed a by-pass load effect due to the parallel compression of the intact face-sheet. The CAI-SS test method was used to study the effect of face-sheet thickness on the damage tolerance assessment. The BAI test method showed similar failure stresses to the CAI-SS tests. A progressive damage finite element model was used to estimate by-pass load and post impact strengths. The simulations showed good agreement with the experiments.
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| 44. |
- Rajput, Moeen S, et al.
(författare)
-
Evaluation of test methods and face-sheet thickness effects in damage tolerance assessment of composite sandwich plates
- 2022
-
Ingår i: Journal of Sandwich Structures and Materials. - : SAGE Publications. - 1099-6362 .- 1530-7972. ; 24:2, s. 1340-1366
-
Tidskriftsartikel (refereegranskat)abstract
- Composite sandwich materials provide high bending performance-to-weight ratios. However, these materials are vulnerable to impact damages which can drastically reduce their load-bearing capability. Presently there is a lack of standardised test methods for impact assessment. This study compares three different test methods for impact assessment; single skin compression after impact (CAI-SS), sandwich compression after impact (CAI-SW) and four-point bending-after-impact (BAI). The CAI-SS test method shows high compressive strength and strain at failure and the tesr is relatively easy to evaluate. For finite size plates with significant impact damage, the CAI-SS test method is recommended for post impact strength assessment. For large sandwich panels with relatively small impact damages the CAI-SW test method could be more relevant since it includes effects of panel asymmetry generated from the impact damage. The BAI test method may be recommended as an alternative to CAI but quite long specimens are required in order to assure compressive failure in the tested face-sheet, making the test both demanding and expensive. On the other hand, lower load levels are required to break the specimens and there is less need for precise machining during specimen manufacturing. A finite element model including progressive damage evolution was used to estimate the post impact strength. The simulations showed generally good agreement with the experiments.
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| 45. |
- Rajput, Moeen S, et al.
(författare)
-
Experimental and numerical study of the response to various impact energy levels for composite sandwich plates with different face thicknesses
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Composite sandwich structures find wide application in the aerospace sector thanks to their lightweight characteristics. However, composite structures are highly susceptible to low velocity impact damage and therefore thorough characterization of the impact response and damage process for the used material configurations is necessary. The present study investigates the effect of face-sheet thickness on the impact response and damage mechanisms, experimentally and numerically. A uni-directional, non-crimp fabric (NCF) is used to build the face-sheets, and a closed cell Rohacell 200 Hero material is used as foam core material. Low-velocity impact tests are performed in a novel instrumented drop-weight rig that is able to capture the true impact response. A range of impact energies are initially utilized in order to identify when low level damage (LLD), barely visible impact damage (BVID) and visible impact damage (VID) occur. A thorough fractography investigation is performed to characterize the impact damage using both destructive and non-destructive testing. The damage from the impacts in terms of dent depth, peak contact force, deflection and absorbed energy is measured. The results show bilinear responses in dent depth vs. impact energy and absorbed energy vs. impact energy. It is found than the BVID energy works well as an indication for the onset of excessive damage. Fractography reveals that there is a failure mode shift between the LLD and the VID energy levels, and that delaminations predominantly grow along the fiber direction and rotate in a spiral pattern through the thickness, following the laminate ply orientations. Finally, a progressive damage finite element model is developed to simulate both the impact response and the delamination extent, incorporating both intra-laminar and inter-laminar damage modes. The simulation shows good agreement with the experiments.
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| 46. |
- Rajput, Moeen S
(författare)
-
Experimental and numerical study of the response to various impact energy levels for composite sandwich plates with different face thicknesses
- 2019
-
Ingår i: Journal of Sandwich Structures and Materials. - : SAGE Publications. - 1099-6362 .- 1530-7972. ; , s. 1654-1682
-
Tidskriftsartikel (refereegranskat)abstract
- Composite sandwich structures find wide application in the aerospace sector thanks to their lightweight characteristics. However, composite structures are highly susceptible to low velocity impact damage and therefore thorough characterization of the impact response and damage process for the used material configurations is necessary. The present study investigates the effect of face-sheet thickness on the impact response and damage mechanisms, experimentally and numerically. A uni-directional, non-crimp fabric is used as reinforcement in the face-sheets, and a closed cell Rohacell 200 Hero polymer foam is used as core material. Low-velocity impact tests are performed in a novel instrumented drop-weight rig that is able to capture the true impact response. A range of impact energies are initially utilized in order to identify when low level damage (LLD), barely visible impact damage (BVID) and visible impact damage (VID) occur. A thorough fractography investigation is performed to characterize the impact damage using both destructive and non-destructive testing. The damage from the impacts in terms of dent depth, peak contact force, deflection and absorbed energy is measured. The results show bilinear responses in dent depth vs. impact energy and absorbed energy vs. impact energy. It is found than the BVID energy works well as an indication for the onset of excessive damage. Fractography reveals that there is a failure mode shift between the LLD and the VID energy levels, and that delaminations predominantly grow along the fiber direction and rotate in a spiral pattern through the thickness, following the laminate ply orientations. Finally, a progressive damage finite element model is developed to simulate both the impact response and the delamination extent, incorporating both intra- laminar and inter-laminar damage modes. The simulation shows good agreement with the experiments.
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| 47. |
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| 48. |
- Rajput, Moeen ud din Saeed, 1987-
(författare)
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Damage Tolerance of Impacted Composite Sandwich Structures
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with damage tolerance of impacted sandwich structures for load bearing applications. Composite sandwich structures find wide application as lightweight solutions in aerospace components, since weight reduction and less fuel emissions are primary concerns for aircraft manufactures. Sandwich structures are built of stiff face-sheet materials bonded to a low-density core material. In this thesis, the face-sheets are composite materials reinforced with carbon fibre non-crimp fabrics whereas the core consists of a closed cell foam material. Sandwich structures are susceptible to impact damage and even a small amount of damage can reduce the residual strength of components significantly. Therefore, damage tolerance assessment of such structures is essential and needs to be taken into account in the design process.Main objective of this thesis is assessment of test methodologies for estimation of compressive properties of foam core materials. An extensive experimental study of different densities of closed cell foam materials is presented and existing test standards are evaluated in this regard. Two different test methods were investigated for strain measurements of the foam material during compression testing assisted by a digital image correlation technique. A parametric study was also performed to investigate the effect of in-plane specimen size on the compressive modulus measurements. Both homogenized and stochastic finite element models are used to back the experimental observations. Different types of boundary conditions were used to simulate the effects of in-plane specimen size and prediction of compressive modulus. The findings were also used as basis for recommendations for updating current test standards.A part of the thesis work concerns the design and construction of a new drop-weight impact rig for low-velocity impact testing of sandwich structures. A test setup was designed to capture the true impact response without adulteration by oscillations. A novel catch mechanism was designed and implemented for preventing secondary impact. A detailed experimental evaluation and uncertainty analysis was also performed to evaluate the drop-weight rig in terms of repeatability and precision.The developed drop-weight rig was used to perform low-velocity impact characterization of sandwich structure with different face-sheet thicknesses. A range of impact energies were investigated for the identification of low level damage (LLD), barely visible impact damage (BVID) and visible impact damage (VID). A thorough fractography study was performed to understand the damage mechanisms at different energy levels and for different face thicknesses. A finite element model was developed to simulate the impact response and delamination extent, including both inter-laminar and intra-laminar damage modes.Finally, the impact damaged specimens were tested for damage tolerance assessment. Both symmetric and asymmetric specimen configurations with different face-sheet thicknesses were investigated. The effect of face-sheet thickness on the residual strength of sandwich structures was studied. Three different test methodologies for damage tolerance testing were investigated and the results were compared. A finite element model was developed for simulation of the edgewise compression test methods and the residual strength predictions were compared with the experimental results.
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| 49. |
- Senneby, Erik, et al.
(författare)
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Genetic relatedness of Streptococcus dysgalactiae isolates causing recurrent bacteraemia
- 2021
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 70:3
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Tidskriftsartikel (refereegranskat)abstract
- Introduction.Streptococcus dysgalactiae subspecies equisimilis (SDSE) is becoming increasingly recognized as an important human pathogen. Recurrent bacteremia with SDSE has been described previously.Aim. The aims of the study were to establish the genetic relatedness of SDSE isolates with emm-type stG643 that had caused recurrent bacteraemia in three patients and to search for signs of horizontal gene transfer of the emm gene in a collection of SDSE stG643 genomes.Hypothesis. Recurring SDSE bacteremia is caused by the same clone in one patient.Methodology. Whole genome sequencing of 22 clinical SDSE stG643 isolates was performed, including three paired blood culture isolates and sixteen isolates from various sites. All assemblies were aligned to a reference assembly and SNPs were extracted. A total of 53 SDSE genomes were downloaded from GenBank. Two phylogenetic trees, including all 75 SDSE isolates, were created. One tree was based on the emm gene only and one tree was based on all variable positions in the genomes.Results. The genomes from the three pairs of SDSE isolates showed high sequence similarity (1-17 SNPs difference between the pairs), whereas the median SNP difference between the 22 isolates in our collection was 1694 (range 1-11257). The paired isolates were retrieved with 7-53 months between episodes. The 22 SDSE isolates from our collection formed a cluster in the phylogenetic tree based on the emm gene, while they were more scattered in the tree based on all variable positions.Conclusions. Our results show that the paired isolates were of the same clonal origin, which in turn supports carriage between bacteraemia episodes. The phylogenetic analysis indicates that horizontal gene transfer of the emm-gene between some of the SDSE isolates has occurred.
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| 50. |
- Senneby, Erik, et al.
(författare)
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Identification of two abundant Aerococcus urinae cell wall-anchored proteins
- 2019
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Ingår i: International Journal of Medical Microbiology. - : Elsevier BV. - 1618-0607 .- 1438-4221. ; 309:7
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Tidskriftsartikel (refereegranskat)abstract
- Aerococcus urinae is an emerging pathogen that causes urinary tract infections, bacteremia and infective endocarditis. The mechanisms through which A. urinae cause infection are largely unknown. The aims of this study were to describe the surface proteome of A. urinae and to analyse A. urinae genomes in search for genes encoding surface proteins. Two proteins, denoted Aerococcal surface protein (Asp) 1 and 2, were through the use of mass spectrometry based proteomics found to quantitatively dominate the aerococcal surface. The presence of these proteins on the surface was also shown using ELISA with serum from rabbits immunized with the recombinant Asp. These proteins had a signal sequence in the amino-terminal end and a cell wall-sorting region in the carboxy-terminal end, which contained an LPATG-motif, a hydrophobic domain and a positively charged tail. Twenty-three additional A. urinae genomes were sequenced using Illumina HiSeq technology. Six different variants of asp genes were found (denoted asp1-6). All isolates had either one or two of these asp-genes located in a conserved locus, designated Locus encoding Aerococcal Surface Proteins (LASP). The 25 genomes had in median 13 genes encoding LPXTG-proteins (range 6-24). For other Gram-positive bacteria, cell wall-anchored surface proteins with an LPXTG-motif play a key role for virulence. Thus, it will be of great interest to explore the function of the Asp proteins of A. urinae to establish a better understanding of the molecular mechanisms by which A. urinae cause disease.
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