| 1. |
- Fernandes, Ricardo A., et al.
(författare)
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A cell topography-based mechanism for ligand discrimination by the T cell receptor
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:28, s. 14002-14010
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Tidskriftsartikel (refereegranskat)abstract
- The T cell receptor (TCR) initiates the elimination of pathogens and tumors by T cells. To avoid damage to the host, the receptor must be capable of discriminating between wild-type and mutated self and nonself peptide ligands presented by host cells. Exactly how the TCR does this is unknown. In resting T cells, the TCR is largely unphosphorylated due to the dominance of phosphatases over the kinases expressed at the cell surface. However, when agonist peptides are presented to the TCR by major histocompatibility complex proteins expressed by antigen-presenting cells (APCs), very fast receptor triggering, i.e., TCR phosphorylation, occurs. Recent work suggests that this depends on the local exclusion of the phosphatases from regions of contact of the T cells with the APCs. Here, we developed and tested a quantitative treatment of receptor triggering reliant only on TCR dwell time in phosphatase-depleted cell contacts constrained in area by cell topography. Using the model and experimentally derived parameters, we found that ligand discrimination likely depends crucially on individual contacts being ∼200 nm in radius, matching the dimensions of the surface protrusions used by T cells to interrogate their targets. The model not only correctly predicted the relative signaling potencies of known agonists and nonagonists but also achieved this in the absence of kinetic proofreading. Our work provides a simple, quantitative, and predictive molecular framework for understanding why TCR triggering is so selective and fast and reveals that, for some receptors, cell topography likely influences signaling outcomes.
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| 2. |
- Jakobsson, Anders, et al.
(författare)
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Vetenskapskommunikation och skolutveckling som en del av den tredje uppgiften
- 2019
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Ingår i: En historiker korsar sitt spår. - : Malmö universitet. - 9789178770335 - 9789178770458 ; , s. 221-237
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- I detta kapitel fokuserar vi hur universitetens samverkan med det omgivande samhället kan bidra med ny forskning och samtidigt verka för spridning av nya forskningsresultat. I forskarskolan Communicate science in school (CSiS) deltar tio lärare i en forskarutbildning där deltagarna efter avslutad utbildning erhåller en licentiatexamen i naturvetenskapernas didaktik. Ett viktigt syfte med forskarskolan är att fortlöpande samla förvaltningschefer, rektorer och forskarstuderande för att diskutera och förstärka skolutveckling i förskolan, grundskolan och gymnasieskolan på vetenskaplig grund. Det innebär att initiera samtal om hur de berörda lärarnas kunskaper ska komma kommunernas skolutveckling till godo efter avlagd examen. Gemensamt för samtliga forskarstuderande har varit att problematisera skolämnenas innehåll i relation till modern forskning i naturvetenskap och teknik men också att ta del av internationell utbildningsvetenskaplig forskning i relation till undervisningsformer och organisering av själva undervisningen.
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| 3. |
- Lagerholm, Charlotte, et al.
(författare)
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Analysing representations of concept in physics textbooks for lower secondary school in Sweden – the concept of pressure
- 2017
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Ingår i: Analysing representations of concept in physics textbooks for lower secondary school in Sweden – the concept of pressure. ; , s. 195-197
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Konferensbidrag (refereegranskat)abstract
- Representations of scientific concepts are important tools for creating understanding of science. In connection with the scientific concepts mentioned in textbooks it is common to use many other forms of representation to clarify them. In this study, we focus on physics textbooks for lower secondary school and more specifically, how the concept of pressure is presented. The examination of the textbooks will be divided into in two parts. In the first part we study the representations that occur from a quantitative perspective. The representations will be sorted into three main categories (Liu & Khine, 2016). For each category there are sub-categories. In the second part of the study, representations will be studied from a qualitative perspective and described with respect to how they are used and interconnected in the textbooks. In this second part, the representations are analysed and sorted into four main categories (Slough, McTigue, Suyeon, & Jennings, 2010). Preliminary results from the first part of the study show that textual representations dominate together with graphical representations in all textbooks, while the mathematical representations only occur occasionally. The second part of the study is on-going and preliminary results will be presented and discussed, together with implication for teaching.
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| 4. |
- Lagerholm, Charlotte, et al.
(författare)
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Säger en bild mer än tusen ord?
- 2019
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Ingår i: Från forskning till fysikundervisning. - Linköping : Linköping University Electronic Press. - 9789179299804 ; , s. 49-59
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Svenska läroböcker i fysik har utvecklats från att vara främst textbaserade till att numera innehålla ett stort antal representationer. Fotografier och teckningar men också variation i teckenstil eller matematiska formler är exempel på representationer som används för att förtydliga innehållet i texten. Studiens huvudsakliga syfte är att analysera vilka representationer som förekommer i fysikläroböcker för högstadiet i Sverige och hur dessa representationer används. För denna studie har ett kategoriseringsverktyg tagits fram. Verktyget används såväl för att kategorisera representationerna som för att analysera användningen av dem. Läroböckerna uppvisar stora likheter när det gäller hur de representerar begrepp. Resultatet visar att liknade representationer används i alla läroböckerna. Böckernas kapitel inleds med stora färgfotografier, inte alltid med ett tydligt syfte eller koppling till innehållet. Få fotografier och teckningar är relaterade till elevers vardag. Matematiska representationer såsom tabeller och formler är sällsynta och ingen av läroböckerna har med något diagram. Sammanfattningsvis är dessa inte läroböcker som kan sättas i händerna på elever utan vägledning från läraren. Ofta förväntas eleverna kombinera text och representation på egen hand där det krävs förkunskaper för att förstå representationerna. Det hade därför varit till nytta om representationerna bidrog med mer detaljerad information om hur de ska läsas. © Nationellt centrum för naturvetenskapernas och teknikens didaktik och författarna. Distribueras av Nationellt centrum för naturvetenskapernas och teknikens didaktik vid Institutionen för samhälls- och välfärdsstudier, Linköpings universitet.
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| 5. |
- Lagerholm, Charlotte
(författare)
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Tryckt bild eller avbildat tryck? : Visuella representationer av begrepp relaterade till tryck i fysikläroböcker för högstadiet
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- AbstractIn this study visual representations of the concept of pressure in five physics textbooks for lower secondary school have been analysed in terms of how they communicate the concept of pressure, and also how these representations work together to explain what pressure is. Examples of visual representations are fonts, photographs, sketches, tables or mathematic formulas. The analysis will answer the research questions; what types of representations are present? How are they used to represent concepts and what affordances do they have? That is, how well do they represent the content? Representations of scientific concepts are important tools for creating an understanding of science. In connection with the scientific concepts mentioned in textbooks it is common to use many other forms of representation to clarify them. This study used content analysis as methodology. First, the presence of representations has been analysed, and sorted into three categories: textual representations, graphical representations and mathematical representations. Second, representations have been analysed with regard to how they support the text in order to reveal the physics content using a model describing four principles: form and function, mental model, placement and semantic integration. Finally, the affordances of the representations are analysed with regard to what they offer the students.The results show that textual representations together with graphical representations dominate in all textbooks, while the mathematical representations only occur occasionally. Although representations should help the reader to understand the content, this study shows that this is not always the case. Most representations are directly linked to the text by depicting objects mentioned in the text. Few representations discuss abstract concepts or processes. The analysis also shows that representations are similar in the textbooks. Most of the representations are placed after or next to the text. Texts and other representations are seldom integrated. The results also show that the multimodal aspect is not fully used. Generally, the images are not combined with other representations, for example text labels or arrows, to illustrate special parts. The study shows that many of the representations have affordances to describe the physics discourse. However, a large portion of them have gone through several steps of transduction, becoming so simplified that their affordances are inaccessible or appresent (hidden) and hence become difficult to link to the content. The meaning of the concept is connected to the context in which they are used. In order to understand the concepts, students also need to understand the context. Many representations do not show their meaning directly. In order to reveal their meaning the representations need to be unpacked, either by their associated representation or by a teacher.A conclusion that can be drawn from this study is that representations in physics text books have appresented affordances that students only can get access to from teaching. Students have to work with text and representations simultaneously. Here teachers are of great importance in providing guidance for students.
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| 6. |
- Pennegård, Eva, et al.
(författare)
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Vetenskapskommunikation och skolutveckling som en del av det tredje uppdraget
- 2019
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Ingår i: En historiker korsar sitt spår : En vänbok till Roger Johansson om att lära sig av historien och lära ut historia - En vänbok till Roger Johansson om att lära sig av historien och lära ut historia. - 9789178770335 - 9789178770458 ; , s. 231-233
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Bokkapitel (populärvet., debatt m.m.)
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| 7. |
- Rodríguez-Varela, Ricardo, et al.
(författare)
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The genetic history of Scandinavia from the Roman Iron Age to the present
- 2023
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Ingår i: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 186:1, s. 32-46
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Tidskriftsartikel (refereegranskat)abstract
- We investigate a 2,000-year genetic transect through Scandinavia spanning the Iron Age to the present, based on 48 new and 249 published ancient genomes and genotypes from 16,638 modern individuals. We find regional variation in the timing and magnitude of gene flow from three sources: the eastern Baltic, the British-Irish Isles, and southern Europe. British-Irish ancestry was widespread in Scandinavia from the Viking period, whereas eastern Baltic ancestry is more localized to Gotland and central Sweden. In some regions, a drop in current levels of external ancestry suggests that ancient immigrants contributed proportionately less to the modern Scandinavian gene pool than indicated by the ancestry of genomes from the Viking and Medieval periods. Finally, we show that a north-south genetic cline that characterizes modern Scandinavians is mainly due to the differential levels of Uralic ancestry and that this cline existed in the Viking Age and possibly earlier.
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