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  • 8551.
    Bergsten, Christer
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Trying to reach the limit: The role of algebra in mathematical reasoning2006In: Proceedings of the 30th conference of the International group for the psychology of mathematics education, vol2 / [ed] J. Novotná, H. Moraová, M. Krátká and N. Stehlíková, Prag: The International Group for the Psychology of Mathematics Education , 2006, 153-160 p.Conference paper (Other academic)
    Abstract [en]

    In this paper the role of algebra in students- mathematical reasoning about limits of functions in undergraduate mathematics is analysed, considering the students- edu¬cational setting. Data from a video study where six students worked in pairs to solve problems on limits of functions, and an analysis of their calculus lectures, indicate that algebra is at the same time a key and a lock to reach the limit in these problems. This double effect is related to the mathematical organisation taught, as well as the students- sense of authority as internal or external.

  • 8552.
    Bergsten, Christer
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Tvillingcirklar2009In: Normat - Nordisk matematisk tidskrift, ISSN 0801-3500, Vol. 57, no 1, 22-31 p.Article in journal (Refereed)
    Abstract [en]

    This ties with previous articles on the arbelos of Archimedes, but instead of starting with two tangent circles, enclosed in a common tangent circle, no conditions are imposed on the two. We then get two cases, whether the circles intersect or not, and a detailed study is made on the nesuing circles. Much of the motivation for this paper is how the problems can be used to illustrate the power of various dynamic geometry software available on the market since the 80's.

  • 8553.
    Bergsten, Christer
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Why do students go to lectures?2011In: Proceedings of the Seventh Congress of the European Society for Research in Mathematics Education / [ed] Marta Pytlak, Tim Rowland, Ewa Svoboda, Rzeszów, Poland: University of Rzeszów, Poland , 2011, 1960-1970 p.Conference paper (Refereed)
    Abstract [en]

    This paper investigates, from a student perspective, the fact that, despite arguments put forward against the educational value of large group lectures, this teaching format prevails and attracts students in undergraduate mathematics education.

  • 8554.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Botten, Geir
    Fuglestad, Anne-Berit
    Grevholm, Barbro
    Holden, Ingvill
    Lingefjärd, Thomas
    Background document: The education and competence development of mathematics teachers in Norway and Sweden2004In: Educating for the future: Proceedings of an International Symposium on Mathematics Teacher Education / [ed] Strässer, R., Brandell, G., Grevholm, B, Helenius, O., Göteborg: The Royal Swedish Academy of Sciences , 2004, 9-38 p.Conference paper (Refereed)
    Abstract [en]

    In this document we present the study material, which was the starting point for the symposium. It consists of experienced teacher educators' and researchers' collected knowledge from classroom and teacher education experience as well as research from the authors and colleagues. The text describes the educational system and the teacher education in Sweden and Norway and recent reforms. It concludes with the identification of some critical issues, which have been, still are or have recently appeared within the educational and competency development of mathematics teachers in Norway and Sweden.

  • 8555.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Dahland, GöteGöteborg University, Sweden.Grevholm, BarbroUniversity of Agder, Norway.
    Research and action in the mathematics classroom: proceedings of MADIF 2, the 2nd Swedish Mathematics Education Research Seminar, Göteborg, January 26-27, 20002002Collection (editor) (Refereed)
  • 8556.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Engelbrecht, Johann
    University of Pretoria, South Africa.
    Kågesten, Owe
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Conceptual and procedural approaches to mathematics in the engineering curriculum: Comparing views of junior and senior engineering students in two countries2017In: Eurasia Journal of Mathematics, Science and Technology Education, ISSN 1305-8223, ISSN 1305-8223, Vol. 33, no 3, 533-553 p.Article in journal (Refereed)
    Abstract [en]

    One challenge for an optimal design of the mathematical components in engineering education curricula is to understand how the procedural and conceptual dimensions of mathematical work can be matched with different demands and contexts from the education and practice of engineers. The focus in this paper is on how engineering students respond to the conceptual-procedural distinction, comparing performance and confidence between second and fourth year groups of students in their answers to a questionnaire comprising conceptually and procedurally focused mathematics problems. We also compare these students’ conceptions on the role of conceptual and procedural mathematics problems within and outside their mathematics studies. Our data suggest that when mathematical knowledge is being recontextualised to engineering subjects or engineering design, a conceptual approach to mathematics is more essential than a procedural approach; working within the mathematical domain, however, the procedural aspects of mathematics are as essential as the conceptual aspects.

  • 8557.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Engelbrecht, Johann
    University of Pretoria, South Africa.
    Kågesten, Owe
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Conceptual or procedural mathematics for engineering students – views of two qualified engineers from two countries2015In: International journal of mathematical education in science and technology, ISSN 0020-739X, E-ISSN 1464-5211, Vol. 46, no 7, 979-990 p.Article in journal (Refereed)
    Abstract [en]

    This study forms part of a collaboration project between universities in South Africa and Sweden in which we investigate whether the emphasis in undergraduate mathematics courses for engineering students would benefit from being more conceptually oriented than a traditional more procedurally oriented way of teaching. In this paper, we report in some detail from two interviews with professional engineers, selected to represent two different ‘poles’ of engineering work. The aim was to explore different kinds of arguments regarding the role of mathematics in engineering work, as well as some common across contexts. Both interviewees feel that conceptual mathematics is more important for engineering work, although the role of the procedural aspect was seen by one of the interviewees also to be important, but in a very intricate way.

  • 8558.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Fransson, Torbjörn
    Växjö universitet.
    Students interacting with an artefact designed to visualise three-dimensional analytic geometry2006In: CERME - Conference of the European Society for Research in Mathematics Education,2005, Barcelona: Universitat Ramon Llull , 2006, 71- p.Conference paper (Refereed)
    Abstract [en]

     To investigate students- ways of working with concrete materials in mathematics, a three-dimensional static artefact was constructed and made available to upper secondary students, with pre-knowledge only in two-dimensional coordinate geo¬metry, for solving problems about planes and straight lines in space. Artefact interactivity was generally high, even students also disregarded the model to work only numerically with the coordinates, building on know¬ledge about lines in two dimensions. The model was used when trying to convince other students in the group. 

  • 8559.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Grevholm, Barbro
    Challenges in mathematics education: Proceedings of MADIF32003Collection (editor) (Refereed)
  • 8560.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Grevholm, BarbroHøgskolen i Agder.
    Conceptions of mathematics: proceedings of norma 01 : the 3rd Nordic Conference on Mathematics Education, Kristianstad, June 8-12, 20012005Collection (editor) (Other academic)
    Abstract [en]

     Proceedings of Norma01, Third Nordic Conference on Mathematics Education, Kristianstad 2001

  • 8561.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Grevholm, BarbroUniversitetet i Agder.
    Developing and researching quality in mathematics teaching and learning2007Collection (editor) (Refereed)
  • 8562.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Grevholm, Barbro
    Knowledgeable teacher educators and linking practices2008In: The International Handbook of mathematics Teacher Education, Volume 4: The Mathematics Teacher Educator as a Developing Professional / [ed] Barbara Jaworski and Terry Woods, Rotterdam: Sense Publishers , 2008, 1, 221-246 p.Chapter in book (Other academic)
    Abstract [en]

    The Handbook of Mathematics Teacher Education, the first of its kind, addresses the learning of mathematics teachers at all levels of schooling to teach mathematics, and the provision of activity and programmes in which this learning can take place. It consists of four volumes. Volume 4 of this handbook has the title The Mathematics Teacher Educator as a Developing Professional. The volume seeks to complement the other three volumes by focusing on knowledge and roles of teacher educators working with teachers in teacher education processes and practices. In this respect it is unique. Chapter authors represent a community of teacher educators world wide who can speak from practical, professional and theoretical viewpoints about what it means to promote teacher education practice. The volume is in 3 main sections. In the first we focus on Challenges to and Theory in Mathematics Teacher Education. Here authors write from perspectives of theory and/or challenge and relate this to examples and insights from their practice. The second section, Reflection On Developing as a Mathematics Teacher Educator has four autobiographical chapters in which authors delineate their experiences as teacher educators and relate these to theoretical and/or moral standpoints. In Section 3, Working With Prospective and Practising Teachers: What We Learn; What We Come to Know, authors write from perspectives on practice - in many cases, the practices in which they themselves have engaged - and relate this to theoretical perspectives and rationales for teacher education programmes. The volume also has an introductory chapter in which the purpose and content of the volume is set out, and a final chapter that syntheses themes and issues from the chapters as a whole, offering an overview of the field and suggesting future directions. Bibliographical Information for the complete set: VOLUME 1: Knowledge and Beliefs in Mathematics Teaching and Teaching Development Peter Sullivan, Monash University, Clayton, Australia and Terry Wood, Purdue University, West Lafayette, USA (eds.) paperback: 978-90-8790-541-5, hardback: 978-90-8790-542-2, ebook: 978-90-8790-543-9 VOLUME 2: Tools and Processes in Mathematics Teacher Education Dina Tirosh, Tel Aviv University, Israel and Terry Wood, Purdue University, West Lafayette, USA (eds.) paperback: 978-90-8790-544-6, hardback: 978-90-8790-545-3, ebook: 978-90-8790-546-0 VOLUME 3: Participants in Mathematics Teacher Education: Individuals, Teams, Communities and Networks Konrad Krainer, University of Klagenfurt, Austria and Terry Wood, Purdue University, West Lafayette, USA (eds.) paperback: 978-90-8790-547-7, hardback: 978-90-8790-548-4, ebook: 978-90-8790-549-1 VOLUME 4: The Mathematics Teacher Educator as a Developing Professional Barbara Jaworski, Loughborough University, UK and Terry Wood, Purdue University, West Lafayette, USA (eds.) paperback: 978-90-8790-550-7, hardback: 978-90-8790-551-4, ebook: 978-90-8790-552-1

  • 8563.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Grevholm, BarbroHøgskolen i Agder.
    Mathematics and language: proceedings of MADIF 4 : the 4th Swedish Mathematics Education Research Seminar, Malmö, January 21-22, 20042004Collection (editor) (Other academic)
    Abstract [en]

     Proceedings of the 4th Swedish Mathematics Education Research Seminar, Malmö 2004 

  • 8564.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Grevholm, Barbro
    Realfag Høgskolen i Agder.
    The didactic divide and the education of teachers of mathematics in Sweden2004In: Nordisk matematikkdidaktikk, ISSN 1104-2176, Vol. 9, no 2, 123-144 p.Article in journal (Refereed)
    Abstract [en]

    On a background of tradition versus renewal, a discussion on recent teacher education reforms in Sweden is given. A balance of different aspects of content and a need for research are seen as critical for the formation of mathematics teacher education. A conception of a -didactic divide- between disciplinary and pedagogical knowledge is used as an analytic tool to describe the rationale behind the design of the reforms. Empirical data from student teachers enrolled in the new teacher education programme highlight how the structure and content of the programme contribute to overcoming the divide.

  • 8565.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Grevholm, Barbro
    Favilli, Franco
    Learning to teach mathematics: expanding the role of practicum as an integrated part of a teacher education programme2009In: The professional education and development of teachers of mathematics. The 15th ICMI Study, New York: Springer , 2009, 1, 57-70 p.Chapter in book (Other academic)
    Abstract [en]

    The premise of the 15th ICMI Study is that teachers are key to students' opportunities to learn mathematics. What teachers of mathematics know, care about, and do is a product of their experiences and socialization, together with the impact of their professional education. The Professional Education and Development of Teachers of Mathematics assembles important new international work- development, research, theory and practice - concerning the professional education of teachers of mathematics. As it examines critical areas to reveal what is known and what significant questions and problems warrant collective attention, the volume also contributes to the strengthening of the international community of mathematics educators. The Professional Education and Development of Teachers of Mathematics is of interest to the mathematics education community as well as to other researchers, practitioners and policy makers concerned with the professional education of teachers.

  • 8566.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Grevholm, BarbroUniversitetet i Agder.Lingefjärd, ThomasGöteborgs universitet.
    Perspectives on mathematical knowledge2009Collection (editor) (Other academic)
  • 8567.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Grevholm, BarbroUniversitetet i Agder.Strömskag Måsöval, HeidiSör-Tröndelag University College.Rönning, FrodeSör-Tröndelag University College.
    Relating practice and reserch in mathematics education: Proceedings of the Fourth Nordic Conference on Mathematics Education2007Collection (editor) (Other academic)
  • 8568.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology. Linköping University, Faculty of Educational Sciences.
    Jablonka, Eva
    Luleå tekniska universitet.
    Commentary on Theories of mathematics education: Is plurality a problem?2010In: Theories of Mathematics Education: Seeking New Frontiers / [ed] B. Sriraman, B. & L. English, New York: Springer , 2010, 111-120 p.Chapter in book (Other academic)
    Abstract [en]

    The chapter by Steve Lerman provides a powerful analysis that helps to make sense of the changing nature of the discourse in mathematics education as a research domain, of its knowledge structure and of the positions of researchers in relation to intellectual traditions ‘outside’ the field as well as in relation to changing pedagogic modes. The reading invited us to expand on the conceptualisation of knowledge structures and discourses in mathematics education as a research domain.

  • 8569.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Jablonka, Eva
    Luleå tekniska universitet.
    Interpreting students' reasoning through the lens of two different languages of description: integration or juxtaposition?2010In: Proceedings of the Sixth Congress of the European Society for Research in Mathematics Education. January 28th - February 1st 2009, Lyon (France) / [ed] V. Durand-Guerrier, S. Soury-Lavergne, & F. Arzarello, Lyon: INSTITUT NATIONAL DE RECHERCHE PÉDAGOGIQUE , 2010, 1555-1564 p.Conference paper (Refereed)
    Abstract [en]

    This contribution exemplifies the interpretation of a common set of data by using two languages of description originating from different theoretical perspectives. One ac- count uses categories from a psychological and the other from a sociological per- spective. The interpretations result in different explanations for the students’ strug- gles with sense making. However, the results cannot be integrated into a combined insight, but only be juxtaposed.

  • 8570.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, The Institute of Technology.
    Jablonka, Eva
    King's College London, UK.
    Mathematics as “Meta-Technology” and “Mind-Power”: Views of engineering students2013In: Proceedings of the Eighth Congress of the European Society for Research in Mathematics Education, Ankara, Turkey: Middle East Technical University , 2013Conference paper (Refereed)
    Abstract [en]

    The paper reports an exploration of first year undergraduate engineering students’ rationales for choosing engineering programmes at master’s level and the potential gains for their future professions they see from studying mathematics. As a means for organising the data, we used some notions of Bourdieu’s theory of the economy of forms of social practice. The study aims to contribute to understanding differences in the students’ experiences of and interest in university mathematics.

  • 8571.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Jablonka, Eva
    King's College London.
    The construction of the ‘transition problem’ by a group of mathematics lecturers2015In: Proceedings of the Ninth Congress of the European Society for Research in Mathematics Education / [ed] Konrad Krainer, Nad'a Vondrová, Prague, Czech Republic: Charles University in Prague, Faculty of Education and ERME , 2015, 2053-2059 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents views of university staff about what has become called the ‘transition problem’ when students start studying mathematics at university. The data are from a focus group interview with eight experienced university lecturers at a Swedish university department that offers mathematics courses for engineering students. We use the portrayal of the problem in the literature as an axis for the discussion.

  • 8572.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, The Institute of Technology.
    Jablonka, Eva
    Luleå tekniska universitet, Luelå.
    Ashjari, Hoda
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, The Institute of Technology.
    Recognising knowledge criteria in undergraduate mathematics education2012In: Evaluation and comparison of mathematical achievement: Dimensions and perspectives: Proceedings of MADIF 8, Umeå, January 24-­‐25, 2012 / [ed] Christer Bergsten, Eva Jablonka, Manya Raman, Linköping: Svensk förening för MatematikDidaktisk Forskning - SMDF, 2012, 101-110 p.Chapter in book (Refereed)
    Abstract [en]

    As part of a larger study on the transition between upper secondary and tertiarymathematics education, this paper reports findings from an investigation of therelation between the students’ understanding of the criteria for legitimate mathematicalknowledge and their achievement during the first year in their undergraduatemathematics studies. As a methodology, we used interviews in whichengineering students were given excerpts from different, more or less formal,mathematics textbooks and asked whether they could rank these texts as being“more or less mathematical” and explain why. The results of our case studyindicate differences in the students’ views that are related to their achievement.

  • 8573.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Jablonka, Eva
    King's College London.
    Ashjari, Hoda
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Övergången från skolans till högskolans matematik: en integrerad studie av en kulturkrock2015In: Resultatdialog 2015 / [ed] Petter Aasen, Eva Björck, Stockholm: Vetenskapsrådet , 2015, 29-41 p.Chapter in book (Other academic)
    Abstract [sv]

    Projektets syfte var att utveckla en integrerad bild av matematiska, didaktiska och sociala dimensioner av matematikutbildning i samband med övergången gymnasium-högskola. Civilingenjörsstudenter intervjuades om sina matematikstudier i jämförelse med gymnasiets. Resultaten visar att de ser skillnader i matematiken på universitetet när det gäller kunskapskriterier, studietakt, undervisning och egna studievanor. Studenter medvetna om dessa skillnader lyckas bäst resultatmässigt. Matematikstudier upplevs annorlunda jämfört med andra ämnen vad gäller den tid och kraft som måste investeras. Intervjuade universitetslärare i matematik menar att övergångsproblemen främst rör studentens eget arbete och naturliga utveckling – dagens studenter måste "kämpa mer på vägen". Bland studenter som nämner eget studieansvar tycks ett fåtal ha haft "övergångsproblem": universitetsstudier beskrivs som en värdefull erfarenhet. De flesta anpassar sitt sätt att studera till de nya kraven men det behövs en ökad tydlighet gentemot de studerande vad dessa exakt innebär.

  • 8574.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Jablonka, Eva
    Luleå tekniska universitet.
    Klisinska, Anna
    Luleå tekniska universitet.
    A remark on didactic transposition theory2010In: Mathematics and mathematics education: Cultural and social dimensions: Proceedings of MADIF7, The Seventh Mathematics Education Research Seminar, Stockholm, January 26-27. 2010 / [ed] C. Bergsten, E. Jablonka, T. Wedege, Linköping: Svensk förening för matematikdidaktisk forskning (SMDF) , 2010, 58-68 p.Conference paper (Refereed)
    Abstract [en]

    With reference to a historical study on the relation between the production and distribution of mathematical knowledge, using calculus as an example, some assumptions in didactic transposition theory, as introduced by Yves Chevallard, are discussed. Given the prominent status of this theory, the paper intends to initiate a debate that could help lifting it out from its relative isolation within mathematics education as a research domain.

  • 8575.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Jablonka, Eva
    Luleå tekniska universitet.
    Klisinska, Anna
    Luleå tekniska universitet.
    Reproduction and distribution of mathematical knowledge in higher education: constructing insiders and outsiders2010In: Mathematics Education and Society: Proceedings of the Sixth International Mathematics Education and Society Conference / [ed] U. Gellert, E. Jablonka, & C. Morgan, Berlin: Freie Universotät Berlin , 2010, 130-140 p.Conference paper (Refereed)
    Abstract [en]

    The design and conduct of calculus courses has been and is an object of curriculardebates and reforms. By the reconstruction of the establishment of the mathematicalsub-area now called ‘calculus’ and its fundamental theorem as a piece ofinstitutionalized mathematical knowledge for the purpose of its reproduction, wereconsider the notion of knowledge recontextualization within the field of knowledgeproduction by showing that standardization of knowledge evolves in a dynamicrelationship with its production. Interviews with mathematicians suggest that they, asteachers, create different recontextualization principles. In undergraduate teachingcalculus they suggest to include the criteria of the field of knowledge production (e.g.proof) for the future ‘insiders’, while for those who will not pursue a career withinthis field, the ‘outsiders’, the criteria change towards computational efficiency.

  • 8576.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, The Institute of Technology.
    Jablonka, EvaLuleå tekniska universitet.Raman, ManyaUmeå universitet.
    Evaluation and comparison of mathematical achievement2012Collection (editor) (Other academic)
  • 8577.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics.
    Jablonka, EvaLuleå tekniska universitet.Wedege, TineMalmö högskola.
    Mathematics and mathematics education: Cultural and social dimensions: Proceedings of MADIF7, The Seventh Mathematics Education Research Seminar, Stockholm, January 26-27, 20102010Collection (editor) (Refereed)
  • 8578.
    Bergsten, Christer
    et al.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Mathematics, Applied Mathematics.
    Lennerstad, Håkan
    Matematiska språk. Sju essäer om symbolspråkets roll i matematiken2008Collection (editor) (Other academic)
    Abstract [sv]

    Språk är ytterst centralt för oss människor i nästan allt vi gör. Hur är förhåller sig matematik till språk? Man kan med fog hävda att matematik är ett ämne med ett stort antal språkliga sidor. I denna bok tar sju personer från skilda områden upp matematikens språkligheter ur sina respektive perspektiv. Resultatet är ett brett och fascinerande landskap, där matematik som rent räknande är en smal och porlande rännil.Författarna som beskriver sin syn på matematikens språkliga kvaliteter är: Christer Kiselman, professor i matematik, Uppsala universitet; Håkan Lennerstad, docent i tillämpad matematik, Blekinge Tekniska högskola; Lars Mouwitz, matematiklärare och doktor i teknologi och yrkeskunnande, Nationellt Centrum för Matematikutbildning, Göteborg; Madeleine Löwing, doktor i matematikdidaktik, Göteborgs universitet; Bo Göranzon, professor i yrkeskunnande och teknologi, Kungliga Tekniska Högskolan, KTH i Stockholm; Östen Dahl, professor i lingvistik, Stockholms universitet; Christer Bergsten, docent i matematikdidaktik, Linköpings universitet

  • 8579.
    Bergsten, Christer
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Educational Sciences.
    Sriraman, BharathUniversity of Montana.
    Refractions of mathematics education: Festschrift for Eva Jablonka2015Collection (editor) (Other academic)
    Abstract [en]

    The diversity of research in mathematics education has been addressed as both, a problem and a strength. When manifested through adherence to different intellectual roots and theoretical orientations, diversions constitute ‘refractions’ of mathematics education. The collection and analysis of empirical data in a study are by necessity refracted through the specific analytical lens employed, as well as the aim of the study itself. Refractions can also refer to looking at old phenomena through new lenses.The chapters in this book are refracted through philosophical, political, mathematical and personal lenses by distinguished authors in the field, addressing issues about the elusive experience of doing mathematics, purification of texts, refractions, mathematics and ethnomathematics, political messages in textbook tasks, mathematics education policy debate, the political in mathematics education research, philosophy and mathematics, meanings and representations, identity of mathematical modeling, and dilemmas in the teaching of calculus.An ancient Sanskrit adage states that Knowledge is something that grows when shared, but shrinks when hoarded. Academics engaged in the generation of new Knowledge are blessed with both the time and the freedom to engage in pursuits that allow for intellectual pleasure. As a phenomenon of the Zeitgeist many have succumbed to the increased corporatization of academic work, engaging in activities for monetary and self advancement purposes. Are there any real intellectuals left in academia, a là Adorno, Bourdieu, Chomsky, Foucault, among others? This Festschrift is dedicated to academics that don't bother with self promotion or aggrandizement of themselves or their ideas in simplistic terms.

  • 8580.
    Bergsten, Gabriella
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Nyström, Ida
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Tillämpning av ”Muda” vid kartläggning och analys av produktion – för att identifiera slöserier och föreslå förbättringsmöjligheter2013Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    På Viledas två anläggningar i Norrköping sker tillverkning respektive konvertering av wettexduk. Uppdragsgivaren, Eva Lindell, upplever att det förekommer mycket slöserier i olika former inom konverteringsanläggningen. Vidare upplever Lindell att många av de slöserier som förekommer hos operatörerna kan reduceras. Examensarbetet utgår ifrån Muda, de åtta slöserierna, och de fem slöserier som studeras och analyseras i detta arbete är överproduktion, onödiga rörelser, väntan, omarbete och överarbete. Slöserierna identifieras främst med hjälp av den kvalitativa metoden spagettidiagram som genomförs under observationer inom anläggningen men under arbetets gång genomförs även en tidsstudie, en enkätundersökning samt utredningar kring företagets struktur, kundorderpunkt och lagerservicenivå. Observationerna utfördes på tre konverteringslinor inom anläggningen hos Vileda. De gav ett entydigt resultat som visade på att uppdragsgivaren hade rätt – det förekommer mycket slöserier, i olika former. Bland annat uppmärksammades att layouten på området kring linorna påverkar förflyttningar av både operatörer och material i mycket stor utsträckning. Samtidigt som spagettidiagrammen ritades upp utfördes en tidsstudie som gav en insikt i hur stor del av den observerade tiden som hela eller delar av en lina stod still. Utifrån tidsstudien upptäcktes att hela eller delar av en lina stod still 11-48 procent av den totala observerade tiden, vilket i störst utsträckning beror på maskinfel. Utredningarna kring företagets struktur, kundorderpunkt samt lagerservicenivå utreddes i samråd med uppdragsgivaren. Utifrån resultatet av utredningarna drogs slutsatsen att det till viss del sker överproduktion inom verksamheten, främst eftersom företagsstrukturen ser ut som den gör. Dock kunde ingen slutsats dras huruvida en eller flera specifika produkter överproduceras eller inte. Enkätundersökningen som genomfördes bland operatörerna som arbetar vid konverteringslinorna gav inspiration till idéerna om möjliga förbättringar inom anläggningen. Utifrån studierna diskuteras ett antal förbättringsmöjligheter som skulle kunna genomföras på kort respektive lång sikt. Att förändra layouten kring konverteringslinorna, flytta på verktyg samt genomföra någon form av vidareutbildning bland operatörerna är exempel på föreslagna förbättringar som skulle kunna genomföras på kort sikt. Att förbättra kommunikationen mellan basproduktion och konvertering, undersöka möjligheter till att uppdatera maskintekniken samt att reducera sampling är exempel på föreslagna förbättringsmöjligheter som företaget skulle kunna genomföra på lång sikt. Sampling innebär att operatörerna måste kontrollera att rätt mängd av aktuell produkt läggs i kartongerna, de kartonger som sedan distribueras till kund. Under observationerna identifierades ett stort problem som leder till flera former av slöseri. På samtliga dukrullar finns ett rullkort med information kring dukens egenskaper, tillverkningsdatum samt en kod som är unik för varje rulle. Rullkortet fästs på dukrullar med hjälp av ett gem, vilket bidrar till flera former av slöserier. Att reducera dessa slöserier genom att ersätta gemet med en annan metod föreslås som en möjlig förbättring.

  • 8581.
    Bergsten, Johan
    et al.
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Chen, Jr-Tai
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gustafsson, Sebastian
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Thorsell, Mattias
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Rorsman, Niklas
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Impact of AlGaN/GaN interface sharpness on HEMT performanceManuscript (preprint) (Other academic)
    Abstract [en]

    The impact of the design and sharpness of the AlGaN/GaN interface in GaN-based HEMTs is investigated. Three structures with different AlGaN/GaN interface properties were grown with hot-wall MOCVD. One structure has a 2-nmthick AlN exclusion layer in between the AlGaN and the GaN, while the other two differ in their sharpness of the Al transition at the AlGaN/GaN interface. The structures with AlN exclusion layer and optimized sharpness of the interface show similar electron mobilities (1760 and 1740 cm2/Vs). HEMTs were processed and evaluated. Gated Hall-measurements indicate that the sharper interface maintains a higher mobility when the electrons are close to the interface compared both to the AlNexclusion layer and the non-optimized structure. The higher mobility manifests as lower parasitic resistance yielding better DC and high frequency performance. Pulsed IV measurements indicate that the sharper interface provide less dispersive effects compared both to the AlN exclusion layer and the optimized interface.

  • 8582.
    Bergsten, Johan
    et al.
    Chalmers, Sweden.
    Chen, Jr-Tai
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Gustafsson, Sebastian
    Chalmers, Sweden.
    Malmros, Anna
    Chalmers, Sweden.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Thorsell, Mattias
    Chalmers, Sweden.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Rorsman, Niklas
    Chalmers, Sweden.
    Performance Enhancement of Microwave GaN HEMTs Without an AlN-Exclusion Layer Using an Optimized AlGaN/GaN Interface Growth Process2016In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 63, no 1, 333-338 p.Article in journal (Refereed)
    Abstract [en]

    The impact of the sharpness of the AlGaN/GaN interface in high-electron mobility transistors (HEMTs) is investigated. Two structures, one with an optimized AlGaN/GaN interface and another with an unoptimized, were grown using hot-wall metal-organic chemical vapor deposition. The structure with optimized sharpness of the interface shows electron mobility of 1760 cm(2)/V . s as compared with 1660 cm(2)/V . s for the nonoptimized interface. Gated Hall measurements indicate that the sharper interface maintains higher mobility when the electrons are close to the interface compared with the nonoptimized structure, indicating less scattering due to alloy disorder and interface roughness. HEMTs were processed and evaluated. The higher mobility manifests as lower parasitic resistance yielding a better dc and high-frequency performance. A small-signal equivalent model is extracted. The results indicate a lower electron penetration into the buffer in the optimized sample. Pulsed-IV measurements imply that the sharper interface provides less dispersive effects at large drain biases. We speculate that the mobility enhancement seen AlGaN/AlN/GaN structures compared with the AlGaN/GaN case is not only related to the larger conduction band offset but also due to a more welldefined interface minimizing scattering due to alloy disorder and interface roughness.

  • 8583.
    Bergsten, Johan
    et al.
    Chalmers, Gothenburg, Sweden.
    Li, Xun
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Nilsson, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Danielsson, Örjan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Rorsman, Niklas
    Chalmers, Gothenburg, Sweden.
    AlGaN/GaN high electron mobility transistors with intentionally doped GaN buffer using propane as carbon precursor2016In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 55, 05FK02-1-05FK02-4 p., 05FK02Article in journal (Refereed)
    Abstract [en]

    AlGaN/GaN high electron mobility transistors (HEMTs) fabricated on a heterostructure grown by metalorganic chemical vapor deposition using analternative method of carbon (C) doping the buffer are characterized. C-doping is achieved by using propane as precursor, as compared to tuningthe growth process parameters to control C-incorporation from the gallium precursor. This approach allows for optimization of the GaN growthconditions without compromising material quality to achieve semi-insulating properties. The HEMTs are evaluated in terms of isolation anddispersion. Good isolation with OFF-state currents of 2 ' 10%6A/mm, breakdown fields of 70V/μm, and low drain induced barrier lowering of0.13mV/V are found. Dispersive effects are examined using pulsed current–voltage measurements. Current collapse and knee walkout effectslimit the maximum output power to 1.3W/mm. With further optimization of the C-doping profile and GaN material quality this method should offer aversatile approach to decrease dispersive effects in GaN HEMTs.

  • 8584.
    Bergsten, Jonas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lindqvist, Mikaela
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Analysis and Improvement of Value Stream Mapping for TitanX Engine Cooling AB2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete går ut på att för TitanX Engine Cooling ABs räkning analysera deras användning av Lean-verktyget Value Stream Mapping (VSM). Detta på grund av att verktyget inte levererar all information som företaget efterfrågar. För att hitta potentiella alternativ till VSM har verktyg och ramverk inom Enterprise Architecture studerats (EA). Utöver detta har även Theory of Constraints och Sex Sigma analyserats. För att undersöka om det är möjligt att även skapa en kostnadsdimension i VSM har påläggskalkylering undersökts. Resultatet av jämförelsen av teorin bakom VSM och hur TitanX använder VSM visar att det finns vissa skillnader, dock är skillnaderna inte så stora och tros inte påverka resultatet av själva kartläggningen. Vidare har analysen givit att EA kan ersätta VSM men också att modellerna och ramverken inom EA är avsevärt mer komplexa och omfattande än VSM. Theory of constraints är integrerbart med Lean och innehåller också en serie mätvärden som ger den information som TitanX efterfrågar.

  • 8585.
    Bergstrand, Fredrik
    et al.
    Linköping University, Department of Computer and Information Science.
    French, Kimberley
    Linköping University, Department of Computer and Information Science.
    Geijer Michaeli, Rebecka
    Linköping University, Department of Computer and Information Science.
    Henziger, Eric
    Linköping University, Department of Computer and Information Science.
    Johansson, Oscar
    Linköping University, Department of Computer and Information Science.
    Kumpulainen, Robert
    Linköping University, Department of Computer and Information Science.
    Rönmark, Erik
    Linköping University, Department of Computer and Information Science.
    Tennivaara, Kristoffer
    Linköping University, Department of Computer and Information Science.
    Tranell, Victor
    Linköping University, Department of Computer and Information Science.
    Interaktiv programmiljö för kryptoanalys2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Det är sedan länge känt, både bland företag och i den akademiska världen, att det krävs strukturerade arbetsmetoder för att lyckas med storskalig programvaruutveckling. Vilka metoder som fungerar bäst är det svårt att göra ett generellt uttalande om eftersom detta till stor del är situationsberoende. Det existerar en ansenlig mängd metoder och processer som finns beskrivna i detalj av deras förespråkare, men ingen metod fungerar felfritt i alla situationer. I den här rapporten beskrivs de metoder en projektgrupp tillämpade under ett kandidatarbete i programvaruutveckling, och konsekvenserna dessa fick för den slutgiltiga produkten.

    Gruppen har kommit fram till att värde har skapats för kunden genom att implementera kundens begärda system, en interaktiv webbapplikation. Underhållbarhet har uppnåtts genom att följa en kodstandard, tillämpa parprogrammering och kodgranskningar samt publicera koden som öppen källkod. Att under möten diskutera gruppmedlemmarnas välmående bidrog till bättre sammanhållning och stämning och därmed ett bättre slutresultat. Många av gruppens svårigheter hade lösts om gruppen haft ett dedikerat kontor.

    Förhoppningen är att de erfarenheter och den kunskap som gruppen tillgodogjort sig under projektet, och dokumenterat i den här rapporten, ska komma till nytta för både projektmedlemmarna och rapportens läsare.

  • 8586.
    Bergstrand, Frida
    et al.
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning.
    Nguyen, Ngan
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning.
    Bakgrundsvariablers påverkan på enkätsvaren i en telefonintervju: En studie om effekt av intervjuarens, respondentens och intervjuns egenskaper2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Norstat recurrently performs a survey that contains questions about how much the respondent is watching different tv-channels, how different media-devices are used, the ownership of different devices and the usage of different tv-channel sites on the internet, social media, internet services, magazine services and streaming services. In this thesis, data from the survey performed during the autumn of 2016 was used. The aim of this thesis is to examine if there is a difference in answers based on different characteristics of the interviewers and respondents. 

    The 15 most important questions from the survey were chosen in this thesis, and to further reduce the number of response variables principal component analysis was used. The new scores that were produced by the analysis were the reduced response variables, which kept the most important information from the questions in the survey. Thereafter multilevel analyses and regression analyses were performed to examine the effects.  

    The results showed that there was an effect of different characteristics in different questions in the survey. The characteristics that showed effect were the age of the interviewer, the length of the employment, the age of the respondent, education, sex and native language. Some of the questions also showed effect based on whether the respondent lived in a metropolitan region or not.

  • 8587.
    Bergstrand, Johan
    Linköping University, Department of Electrical Engineering, Electronics System.
    Förbättra SNR i en digital TV-box genom översampling av A/D-omvandlare2010Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vår uppgift är att undersöka om vi kan förbättra utsignalens kvalité från ett digitalt TV-kort genom att översampla A/D-omvandlare. Vi kommer att programmera vår kod i en FPGA och i den finns enbart 3 stycken multiplikatorer lediga. Utgången från vårt filter ska ha samma frekvens som innan översamplingen, vi kommer därför att bygga ett FIR-filter som decimerar signalen. Vi valde detta filter för att kunna utnyttja symmetri och minimera antalet multiplikatorer. Vi använde ett filter med ordningen 44 vilket ger 45 koefficienter. Dessa koefficienter beräknades i Matlab med hjälp av funktionen ”firls” som minimerar energivärdet i stoppbandet.

     

    Vi utförde mätningar på SNR samt grupplöptiden. Dessa visade att SNR förbättrades endast 0,7 dB samt att grupplöptiden inte påverkades nämnvärt. För att kunna förbättra SNR och hitta felkällan som begränsar signalen gjorde vi följande åtgärder.

     

    • Fastställde att instrumenten verkligen kunde mäta så höga decibelvärden.
    • Att det inte finns några begränsningar på utgången.
    • Att det inte finns några störningar på ingången.
    • Ändrade koefficienter i filterkoden för att variera filtrets egenskaper.

     

    De åtgärder vi gjorde förbättrade inte SNR på konstruktionen. På grund av tidsbrist kunde vi inte fortsätta våra undersökningar. Det vi skulle gjort från början är att skapa en testbänk till vår filterkod för att kunna verifiera att den fungerade. Vi kan inte med säkerhet fastställa att filtret verkligen fungerar enligt de initiala kraven. Vi skulle även försöka förbättra klockan till FPGA:n eftersom denna kan skapa klockjitter. Vi skulle även försöka skapa fler mätpunkter i kedjan, att kunna mäta signalen efter A/D-omvandlaren och direkt efter vårt filter.

  • 8588.
    Bergstrand, Martin
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Automatic analysis of eye tracker data from a driving simulator2008Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The movement of a persons eyes is an interesting factor to study in different research areas where attention is important, for example driving. In 2004 the Swedish national road and transport research institute (VTI) introduced Simulator III – their third generation of driving simulators. Inside Simulator III a camera based eye tracking system is installed that records the eye movements of the driver. To be useful, the raw data from the eye tracking system needs to be analyzed and concentrated into a number of measures relevant for the research at VTI.

    This thesis presents methods to analyze the data from the eye tracker and transform it into something more useful. A world coordinate system is setup to connect the eye tracking system with the real world in a consistent way. A set of measures is collected, mainly from ISO and SAE standards, to be used as output from the analysis. Finally an application is developed for performing the analysis. The application reads the data from the eye tracker and the simulator, analyzes the data, and outputs a set of eye movement measures usable for the researchers at VTI.

  • 8589.
    Bergstrand, Sara
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Preventing pressure ulcers by assessment of the microcirculation in tissue exposed to pressure2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The overall aim of this thesis was to combine optical methods into a system with the ability to simultaneously measure blood flow changes at different tissue depths. The goal of such a system was to reveal vascular mechanisms relevant to pressure ulcer etiology under clinically relevant conditions and in relation to the evaluation of pressure-redistribution support surfaces.

    This thesis consists of four quantitative, cross-sectional studies measuring blood flow responses before, during, and after pressure exposure of the sacral tissue. Two optical methods – photoplethysmography and laser Doppler flowmetry – were combined in a newly developed system that has the ability to discriminate blood flows at different tissue depths. Studies I and II explored blood flow responses at different depths in 17 individuals. In Study I the blood flow was related to tissue thickness and tissue compression during pressure exposure of ≥ 220 mmHg. In Study II, the sacral tissue was loaded with 37.5 mmHg and 50.0 mmHg, and the variation in blood flow was measured. Studies III and IV included 42 healthy individuals < 65 years, 38 healthy individuals ≥ 65 years, and 35 patients ≥ 65 years. Study III included between-subject comparisons of blood flow and pressure between individuals in the three study groups lying in supine positions on a standard hospital mattress. Study IV added within-subject comparisons while the individual was lying on four different types of mattress. The studies explored the vascular phenomena pressure-induced vasodilation (PIV) and reactive hyperemia (RH).

    The most common blood flow response to tissue exposure in this thesis was PIV, although a decrease in blood flow (a lack of PIV) was observed in some individuals. The patients tended to have higher interface pressure during pressure exposure than the healthy groups but no differences in blood flow responses were seen. Our results showed that pressure levels that are normally considered to be harmless could have a significant effect on the microcirculation in different tissue structures. Differences in individual blood flow responses in terms of PIV and RH were seen, and a larger proportion of individuals lacked these responses in the deeper tissue structures compared to more superficial tissue structures.

    This thesis identified PIV and RH that are important vascular mechanisms for pressure ulcer development and revealed for the first time that PIV and RH are present at different depths under clinically relevant conditions. The thesis also identified a population of individuals not previously identified who lack both PIV and RH and seem to be particularly vulnerable to pressure exposure. Further, this thesis has added a new perspective to the microcirculation in pressure ulcer etiology in terms of blood flow regulation and endothelial function that are anchored in clinically relevant studies. Finally, the evaluation of pressureredistribution support surfaces in terms of mean blood flow during and after tissue exposure was shown to be unfeasible, but the assessment of PIV and RH could provide a new possibility for measuring individual physiological responses that are known to be related to pressure ulcer development.

    List of papers
    1. Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype
    Open this publication in new window or tab >>Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype
    2010 (English)In: MICROCIRCULATION, ISSN 1073-9688, Vol. 17, no 4, 311-319 p.Article in journal (Refereed) Published
    Abstract [en]

    Pandgt;Objective: The aim was to investigate the existence of sacral tissue blood flow at different depths in response to external pressure and compression in elderly individuals using a newly developed optical probe prototype. Methods: The tissue blood flow and tissue thickness in the sacral area were measured during load in 17 individuals using laser Doppler flowmetry and photoplethysmography in a combined probe, and digital ultrasound. Results: The mean age was 68.6 +/- 7.0 years. While loading, the mean compression was 60.3 +/- 11.9%. The number of participants with existing blood flow while loading increased with increased measurement depth. None had enclosed blood flow deep in the tissue and at the same time an existing more superficial blood flow. Correlation between tissue thickness and BMI in unloaded and loaded sacral tissue was shown: r = 0.68 (P = 0.003) and r = 0.68 (P = 0.003). Conclusions: Sacral tissue is highly compressed by external load. There seems to be a difference in responses to load in the different tissue layers, as occluded blood flow in deeper tissue layers do not occur unless the blood flow in the superficial tissue layers is occluded.

    Place, publisher, year, edition, pages
    Taylor and Francis, 2010
    Keyword
    pressure ulcer, photoplethysmography, laser Doppler flowmetry, non-invasive, tissue blood flow
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-56449 (URN)10.1111/j.1549-8719.2010.00027.x (DOI)000277123800008 ()
    Note
    This is an electronic version of an article published in: Sara Bergstrand, Toste Länne, Maria Linden and Margareta Lindgren, Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype, 2010, MICROCIRCULATION, (17), 4, 311-319. MICROCIRCULATION is available online at informaworldTM: http://dx.doi.org/10.1111/j.1549-8719.2010.00027.x Copyright: Taylor and Francis http://www.tandf.co.uk/journals/default.asp Available from: 2010-05-17 Created: 2010-05-17 Last updated: 2017-03-27
    2. Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques
    Open this publication in new window or tab >>Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques
    Show others...
    2009 (English)In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 15, no 2, 139-147 p.Article in journal (Refereed) Published
    Abstract [en]

    Background/purpose: This study has evaluated a multi-parametric system combining laser Doppler flowmetry and photoplethysmography in a single probe for the simultaneous measurement of blood flow at different depths in the tissue. This system will be used to facilitate the understanding of pressure ulcer formation and in the evaluation of pressure ulcer mattresses.

    Methods: The blood flow in the tissue over the sacrum was measured before, during and after loading with 37.5 mmHg, respectively, 50.0 mmHg. The evaluation of the system consisted of one clinical part, and the other part focusing on the technicalities of the probe prototype.

    Results: An increase in blood flow while loading was the most common response, but when the blood flow decreased during loading it was most affected at the skin surface and the blood flow responses may be different due to depths of measurement. Reactive hyperaemia may occur more frequently in the superficial layers of the tissue.

    Conclusion: The study showed that the new system is satisfactory for measuring tissue blood flow at different depths. The laser Doppler complements the photoplethysmography, and further development of the system into a thin flexible probe with the ability to measure a larger area is required.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2009
    Keyword
    pressure ulcers, blood flow, photoplethysmography, laser Doppler flowmetry, non-invasive
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-18018 (URN)10.1111/j.1600-0846.2008.00337.x (DOI)
    Note

    This is the authors’ version of the following article: Sara Bergstrand, Lars-Göran Lindberg, Anna-Christina Ek and Margareta Lindgren, Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques, 2009, SKIN RESEARCH AND TECHNOLOGY, (15), 2, 139-147. which has been published in final form at: http://dx.doi.org/10.1111/j.1600-0846.2008.00337.x Copyright: Blackwell Publishing Ltd http://www.blackwellpublishing.com/

    Available from: 2009-05-26 Created: 2009-05-04 Last updated: 2014-08-29Bibliographically approved
    3. Pressure-induced vasodilation and reactive hyperemia at different depths in sacral tissue under clinically relevant conditions
    Open this publication in new window or tab >>Pressure-induced vasodilation and reactive hyperemia at different depths in sacral tissue under clinically relevant conditions
    Show others...
    2014 (English)In: Microcirculation, ISSN 1073-9688, Vol. 21, no 8, 761-771 p.Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVE: To characterize pressure-induced vasodilatation and reactive hyperemia at different sacral tissue depths in different populations under clinically relevant pressure exposure.

    METHODS: Forty-two subjects (< 65 years), 38 subjects (≥ 65 years), and 35 patients (≥ 65 years) participated. Interface pressure, skin temperature, and blood flow at tissue depths of 1 mm, 2 mm, and 10 mm (using laser Doppler flowmetry and photoplethysmography) were measured in the sacral tissue before, during, and after load in a supine position.

    RESULTS: pressure-induced vasodilatation and reactive hyperemia were observed at three tissue depths. At 10 mm depth, the proportion of subjects with a lack of pressure-induced vasodilatation was higher compared to superficial depths. The patients had higher interface pressure during load than the healthy individuals, but there were no significant differences in blood flow. Twenty-nine subjects in all three study groups were identified with a lack of pressure-induced vasodilatation and reactive hyperemia.

    CONCLUSIONS: pressure-induced vasodilatation and reactive hyperemia can be measured at different tissue depths. A lack of these responses was found in healthy individuals as well as in patients indicating an innate susceptibility in some individuals, and are potential important factors to evaluate in order to better understand the etiology of pressure ulcers.

    Place, publisher, year, edition, pages
    John Wiley & Sons, 2014
    Keyword
    Pressure ulcer, photoplethysmography, laser Doppler flowmetry, non-invasive, tissue blood flow
    National Category
    Nursing Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-109950 (URN)10.1111/micc.12160 (DOI)000344789400010 ()25100630 (PubMedID)
    Available from: 2014-08-29 Created: 2014-08-29 Last updated: 2015-06-09Bibliographically approved
    4. Microcirculatory responses of sacral tissue in healthy individuals and inpatients on different pressure-redistribution mattresses
    Open this publication in new window or tab >>Microcirculatory responses of sacral tissue in healthy individuals and inpatients on different pressure-redistribution mattresses
    Show others...
    2015 (English)In: Journal of Wound Care, ISSN 0969-0700, E-ISSN 2052-2916, Vol. 24, no 8, 346-358 p.Article in journal (Refereed) Published
    Abstract [en]

    Objective: The aim of this study was to explore the interaction between interface pressure and pressure-induced vasodilation and reactive hyperemia with different pressureredistribution mattresses.

    Method: A cross-sectional study was performed with a convenience sample of 42 healthy individuals between 18 and 64 years of age, 38 healthy individuals 65 years or older, and 35 inpatients 65 years or older at a university hospital in Sweden. Blood flow was measured at depths of 1 mm, 2 mm, and 10 mm using a combined system of laser Doppler flowmetry and photoplethysmography. The blood flow, interface pressure and skin temperature were measured in the sacral tissue before, during, and after load while lying on one standard hospital mattress and three different pressure-redistribution mattresses.

    Results: There were significant differences between the three foam mattresses with regard to average sacral pressure, peak sacral pressure, and local probe pressure with the lowest values at the visco-elastic foam/air mattress (23.5 ± 2.5 mmHg, 49.3 ± 11.1 mmHg, 29.2 ± 14.0 mmHg respectively). A greater proportion of subjects had affected blood flow in terms of lack of pressure-induced vasodilation on the visco-elastic foam/air mattress compared to the alternating pressure mattress at tissue depths of 2 mm (39.0% vs. 20.0%, respectively) and 10 mm (56.9 % vs. 35.1%, respectively). Eleven individuals, including subjects in all three subject groups were identified with no pressure-induced vasodilation or reactive hyperemia in any mattress, and this was considered a high-risk blood flow response.

    Conclusion: Interface pressure magnitudes considered not harmful during pressure-exposure lying on different pressure-redistribution mattresses can affect the microcirculation in different tissue structures. Despite having the lowest pressure values compared to the other mattresses, the visco-elastic foam/air mattress had the highest proportion of subjects with decreased blood flow indicating a more affected blood flow. Three young healthy individuals were identified with the high-risk blood flow response, indicating an innate vulnerability to pressure exposure and may not benefit from pressure-redistribution mattresses. Finally it was shown that the evaluation of pressure-redistribution support surfaces in terms of mean blood flow during and after tissue exposure is not feasible but assessment of pressure-induced vasodilation and reactive hyperemia could be a new possibility to assess individualized physiological measurements of mechanisms known to be related to pressure ulcer development.

    Keyword
    interface pressure, pressure-induced vasodilation, pressure ulcer, reactive hyperemia, tissue blood flow
    National Category
    Nursing Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-109951 (URN)10.12968/jowc.2015.24.8.346 (DOI)000359210200004 ()
    Note

    Vid tiden för disputationen var publikationen ett manuskript ("Exploring pressure-induced microcirculatory responses in sacral tissue in healthy individuals and inpatients on different pressure-redistribution mattresses")

    Funding text: None declared. The study was funded by the Swedish Research Council, the Faculty of Health Sciences at Linkoping University, Region of Ostergotland., King GustafV and Queen Victoria's Freemason Foundation, NovaMedTech, and the European Union Regional Development Fund.

    Available from: 2014-08-29 Created: 2014-08-29 Last updated: 2017-03-01Bibliographically approved
  • 8590.
    Bergstrand, Sara
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Tissue Blood Flow Responses to External Pressure Using LDF and PPG: Testing a System Developed for Pressure Ulcer Research2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Pressure ulcers are a problem for immobile individuals, and having pressure ulcers impact and restrict the daily and are often associated with pain. Pressure ulcers occur frequently and cause high costs for the health care system. The prevention of pressure ulcers by focussing on different mattresses and overlays aimed to reduce the interface pressure or the pressure exposure of the tissue. The problem is the poor evaluation of this type of equipment. There are important factors regarding pressure ulcer development, pressure, shear, temperature and humidity. People are affected by external pressure in different ways and therefore it is preferable to measure the effect of pressure as a complement to the pressure measurement and thus we consider blood flow measurements to be a suitable method.

    Aims: The aim of Study I, the first part in this thesis was to investigate the existence of sacral tissue blood flow at different depths in response to external pressure in elderly individuals as a part of evaluation of a. newly developed system. The aim of Study II, the second part was to evaluate a multiparametric system combining LDF and photoplethysmography into a single probe, for the simultaneous measurement of blood flow at different depths in the sacral tissue when the tissue is exposed to external load. This new system will be used to facilitate the understanding of pressure ulcer formation.

    Methods: To be able to observe tissue blood flow, the non-invasive optical methods laser Doppler flowmetry and photoplethysmography were used. In this thesis a newly developed prototype probe was used, combining the two methods. Green light and infrared light were used in the PPG instrument for penetrating the depths of approximately 2 mm, 8 mm and 20 mm depths. A HeNe laser was used to measure the superficial skin blood flow, <1 mm depth. The prototype probe, made of silicone was fixed in a stiff 10×10 cm plate.

    Seventeen active individuals over the age of 60 were recruited for the two studies. In Study I, the subject´s sacral blood flow and tissue thickness (using ultrasound) were measured in unloaded position and in supine position loading the area with their own body weight. In Study II, the sacral area was provoked with external load at 37.5 mmHg and 50.0 mmHg and the relative change in blood flow at different depths was observed before, during and after load.

    Results: Study I showed that the sacral tissue in elderly individuals is highly affected by load and is compressed by 60.3 ± 11.9%. The mean sacral tissue thickness was 26 ± 13 mm in unloaded tissue and 10 ± 6 mm in loaded tissue. Correlations were found between BMI and tissue thickness: both TTunload r=0.68 (p=0.003) and TTload r=0.68 (p=0.003). Almost all subjects had affected blood flow superficially but only occasionally deeper in the tissue and findings may indicate that the blood flow is occluded in the superficial layer before it is occluded deeper in the tissue structure. The most common response in Study II was an increase in blood flow while loading. In those occasions when the blood flow decreased, it was mostly affected at the skin surface and the reactive hyperaemia occurred more frequently in the superficial tissue structures. The blood flow responses may be different in the different tissue layers.

    Conclusions: The newly developed system was found to be suitable for measuring tissue blood flow at different depths; however the prototype probe had some limitations that will be solved in the further development of the system into a thin flexible probe with ability to measure a larger area.

    List of papers
    1. Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype
    Open this publication in new window or tab >>Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype
    2010 (English)In: MICROCIRCULATION, ISSN 1073-9688, Vol. 17, no 4, 311-319 p.Article in journal (Refereed) Published
    Abstract [en]

    Pandgt;Objective: The aim was to investigate the existence of sacral tissue blood flow at different depths in response to external pressure and compression in elderly individuals using a newly developed optical probe prototype. Methods: The tissue blood flow and tissue thickness in the sacral area were measured during load in 17 individuals using laser Doppler flowmetry and photoplethysmography in a combined probe, and digital ultrasound. Results: The mean age was 68.6 +/- 7.0 years. While loading, the mean compression was 60.3 +/- 11.9%. The number of participants with existing blood flow while loading increased with increased measurement depth. None had enclosed blood flow deep in the tissue and at the same time an existing more superficial blood flow. Correlation between tissue thickness and BMI in unloaded and loaded sacral tissue was shown: r = 0.68 (P = 0.003) and r = 0.68 (P = 0.003). Conclusions: Sacral tissue is highly compressed by external load. There seems to be a difference in responses to load in the different tissue layers, as occluded blood flow in deeper tissue layers do not occur unless the blood flow in the superficial tissue layers is occluded.

    Place, publisher, year, edition, pages
    Taylor and Francis, 2010
    Keyword
    pressure ulcer, photoplethysmography, laser Doppler flowmetry, non-invasive, tissue blood flow
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-56449 (URN)10.1111/j.1549-8719.2010.00027.x (DOI)000277123800008 ()
    Note
    This is an electronic version of an article published in: Sara Bergstrand, Toste Länne, Maria Linden and Margareta Lindgren, Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype, 2010, MICROCIRCULATION, (17), 4, 311-319. MICROCIRCULATION is available online at informaworldTM: http://dx.doi.org/10.1111/j.1549-8719.2010.00027.x Copyright: Taylor and Francis http://www.tandf.co.uk/journals/default.asp Available from: 2010-05-17 Created: 2010-05-17 Last updated: 2017-03-27
    2. Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques
    Open this publication in new window or tab >>Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques
    Show others...
    2009 (English)In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 15, no 2, 139-147 p.Article in journal (Refereed) Published
    Abstract [en]

    Background/purpose: This study has evaluated a multi-parametric system combining laser Doppler flowmetry and photoplethysmography in a single probe for the simultaneous measurement of blood flow at different depths in the tissue. This system will be used to facilitate the understanding of pressure ulcer formation and in the evaluation of pressure ulcer mattresses.

    Methods: The blood flow in the tissue over the sacrum was measured before, during and after loading with 37.5 mmHg, respectively, 50.0 mmHg. The evaluation of the system consisted of one clinical part, and the other part focusing on the technicalities of the probe prototype.

    Results: An increase in blood flow while loading was the most common response, but when the blood flow decreased during loading it was most affected at the skin surface and the blood flow responses may be different due to depths of measurement. Reactive hyperaemia may occur more frequently in the superficial layers of the tissue.

    Conclusion: The study showed that the new system is satisfactory for measuring tissue blood flow at different depths. The laser Doppler complements the photoplethysmography, and further development of the system into a thin flexible probe with the ability to measure a larger area is required.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2009
    Keyword
    pressure ulcers, blood flow, photoplethysmography, laser Doppler flowmetry, non-invasive
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-18018 (URN)10.1111/j.1600-0846.2008.00337.x (DOI)
    Note

    This is the authors’ version of the following article: Sara Bergstrand, Lars-Göran Lindberg, Anna-Christina Ek and Margareta Lindgren, Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques, 2009, SKIN RESEARCH AND TECHNOLOGY, (15), 2, 139-147. which has been published in final form at: http://dx.doi.org/10.1111/j.1600-0846.2008.00337.x Copyright: Blackwell Publishing Ltd http://www.blackwellpublishing.com/

    Available from: 2009-05-26 Created: 2009-05-04 Last updated: 2014-08-29Bibliographically approved
  • 8591.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Källman, Ulrika
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Department of Dermatology, Södra Älvsborgs Sjukhus, Borås, Sweden.
    Ek, Anna-Christina
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Health Care in Linköping.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences.
    Lindgren, Margareta
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Microcirculatory responses of sacral tissue in healthy individuals and inpatients on different pressure-redistribution mattresses2015In: Journal of Wound Care, ISSN 0969-0700, E-ISSN 2052-2916, Vol. 24, no 8, 346-358 p.Article in journal (Refereed)
    Abstract [en]

    Objective: The aim of this study was to explore the interaction between interface pressure and pressure-induced vasodilation and reactive hyperemia with different pressureredistribution mattresses.

    Method: A cross-sectional study was performed with a convenience sample of 42 healthy individuals between 18 and 64 years of age, 38 healthy individuals 65 years or older, and 35 inpatients 65 years or older at a university hospital in Sweden. Blood flow was measured at depths of 1 mm, 2 mm, and 10 mm using a combined system of laser Doppler flowmetry and photoplethysmography. The blood flow, interface pressure and skin temperature were measured in the sacral tissue before, during, and after load while lying on one standard hospital mattress and three different pressure-redistribution mattresses.

    Results: There were significant differences between the three foam mattresses with regard to average sacral pressure, peak sacral pressure, and local probe pressure with the lowest values at the visco-elastic foam/air mattress (23.5 ± 2.5 mmHg, 49.3 ± 11.1 mmHg, 29.2 ± 14.0 mmHg respectively). A greater proportion of subjects had affected blood flow in terms of lack of pressure-induced vasodilation on the visco-elastic foam/air mattress compared to the alternating pressure mattress at tissue depths of 2 mm (39.0% vs. 20.0%, respectively) and 10 mm (56.9 % vs. 35.1%, respectively). Eleven individuals, including subjects in all three subject groups were identified with no pressure-induced vasodilation or reactive hyperemia in any mattress, and this was considered a high-risk blood flow response.

    Conclusion: Interface pressure magnitudes considered not harmful during pressure-exposure lying on different pressure-redistribution mattresses can affect the microcirculation in different tissue structures. Despite having the lowest pressure values compared to the other mattresses, the visco-elastic foam/air mattress had the highest proportion of subjects with decreased blood flow indicating a more affected blood flow. Three young healthy individuals were identified with the high-risk blood flow response, indicating an innate vulnerability to pressure exposure and may not benefit from pressure-redistribution mattresses. Finally it was shown that the evaluation of pressure-redistribution support surfaces in terms of mean blood flow during and after tissue exposure is not feasible but assessment of pressure-induced vasodilation and reactive hyperemia could be a new possibility to assess individualized physiological measurements of mechanisms known to be related to pressure ulcer development.

  • 8592.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Källman, Ulrika
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Department of Dermatology, Södra Älvsborgs Sjukhus, Borås, Sweden.
    Ek, Anna-Christina
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Health Care in Linköping.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Anaesthesiology and Intensive Care in Linköping.
    Lindgren, Margareta
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Pressure-induced vasodilation and reactive hyperemia at different depths in sacral tissue under clinically relevant conditions2014In: Microcirculation, ISSN 1073-9688, Vol. 21, no 8, 761-771 p.Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To characterize pressure-induced vasodilatation and reactive hyperemia at different sacral tissue depths in different populations under clinically relevant pressure exposure.

    METHODS: Forty-two subjects (< 65 years), 38 subjects (≥ 65 years), and 35 patients (≥ 65 years) participated. Interface pressure, skin temperature, and blood flow at tissue depths of 1 mm, 2 mm, and 10 mm (using laser Doppler flowmetry and photoplethysmography) were measured in the sacral tissue before, during, and after load in a supine position.

    RESULTS: pressure-induced vasodilatation and reactive hyperemia were observed at three tissue depths. At 10 mm depth, the proportion of subjects with a lack of pressure-induced vasodilatation was higher compared to superficial depths. The patients had higher interface pressure during load than the healthy individuals, but there were no significant differences in blood flow. Twenty-nine subjects in all three study groups were identified with a lack of pressure-induced vasodilatation and reactive hyperemia.

    CONCLUSIONS: pressure-induced vasodilatation and reactive hyperemia can be measured at different tissue depths. A lack of these responses was found in healthy individuals as well as in patients indicating an innate susceptibility in some individuals, and are potential important factors to evaluate in order to better understand the etiology of pressure ulcers.

  • 8593.
    Bergstrand, Sara
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Nursing Science.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Ek, Anna-Christina
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Nursing Science. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine.
    Lindgren, Margareta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Nursing Science.
    Blood flow at different depth in the tissue measured with PPG and laser Doppler technique2008In: Third Congress of the World Unionof Wound Healing Societies,2008, 2008, 31-31 p.Conference paper (Other academic)
    Abstract [en]

       

  • 8594.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Ek, Anna-Christina
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine.
    Lindén, Maria
    Mälardalen University, Västerås, Sweden.
    Lindgren, Margareta
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques2009In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 15, no 2, 139-147 p.Article in journal (Refereed)
    Abstract [en]

    Background/purpose: This study has evaluated a multi-parametric system combining laser Doppler flowmetry and photoplethysmography in a single probe for the simultaneous measurement of blood flow at different depths in the tissue. This system will be used to facilitate the understanding of pressure ulcer formation and in the evaluation of pressure ulcer mattresses.

    Methods: The blood flow in the tissue over the sacrum was measured before, during and after loading with 37.5 mmHg, respectively, 50.0 mmHg. The evaluation of the system consisted of one clinical part, and the other part focusing on the technicalities of the probe prototype.

    Results: An increase in blood flow while loading was the most common response, but when the blood flow decreased during loading it was most affected at the skin surface and the blood flow responses may be different due to depths of measurement. Reactive hyperaemia may occur more frequently in the superficial layers of the tissue.

    Conclusion: The study showed that the new system is satisfactory for measuring tissue blood flow at different depths. The laser Doppler complements the photoplethysmography, and further development of the system into a thin flexible probe with the ability to measure a larger area is required.

  • 8595.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Lindberg, Lars-Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Lindén, Maria
    n/a.
    Ek, Anna-Christina
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Länne, Toste
    Linköping University, Department of Medicine and Health Sciences. Linköping University, Faculty of Health Sciences.
    Lindgren, Margareta
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Tissue blood flow responses to external pressure in the sacral region using PPG and laser Doppler technique.2009In: European Pressure Ulcer Advisory Panels, Amsterdam., 2009Conference paper (Refereed)
  • 8596.
    Bergstrand, Sara
    et al.
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Länne, Toste
    Linköping University, Department of Medicine and Health Sciences, Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Linden, Maria
    Mälardalen University.
    Lindgren, Margareta
    Linköping University, Department of Medicine and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype2010In: MICROCIRCULATION, ISSN 1073-9688, Vol. 17, no 4, 311-319 p.Article in journal (Refereed)
    Abstract [en]

    Pandgt;Objective: The aim was to investigate the existence of sacral tissue blood flow at different depths in response to external pressure and compression in elderly individuals using a newly developed optical probe prototype. Methods: The tissue blood flow and tissue thickness in the sacral area were measured during load in 17 individuals using laser Doppler flowmetry and photoplethysmography in a combined probe, and digital ultrasound. Results: The mean age was 68.6 +/- 7.0 years. While loading, the mean compression was 60.3 +/- 11.9%. The number of participants with existing blood flow while loading increased with increased measurement depth. None had enclosed blood flow deep in the tissue and at the same time an existing more superficial blood flow. Correlation between tissue thickness and BMI in unloaded and loaded sacral tissue was shown: r = 0.68 (P = 0.003) and r = 0.68 (P = 0.003). Conclusions: Sacral tissue is highly compressed by external load. There seems to be a difference in responses to load in the different tissue layers, as occluded blood flow in deeper tissue layers do not occur unless the blood flow in the superficial tissue layers is occluded.

  • 8597. Bergstrom, A
    et al.
    Astrom, H
    Swedish Natl Rd & Transport Res Inst, S-58195 Linkoping, Sweden Dalarna Univ, S-78188 Borlange, Sweden.
    Magnusson, R
    Friction measurement on cycleways using a portable friction tester2003In: Journal of cold regions engineering, ISSN 0887-381X, Vol. 17, no 1, 37-57 p.Article in journal (Refereed)
    Abstract [en]

    In seeking to promote cycling in wintertime, it is desirable to understand how important the winter maintenance service level is in people's decision to cycle or not,, and methods to compare different road conditions on cycleways are therefore needed. By measuring friction, an assessment of the service level can be achieved, but methods available often involve the use of large vehicles, which can lead to overloading damage on cycleways, and constitute a safety risk for cyclists and pedestrians. A portable friction tester (PFT), originally designed to measure friction on road markings, was thought to be an appropriate instrument for cycleways and was, therefore, tested on different winter road conditions, and on different cycleway pavement materials. In this study, it was found that the PFT is a valuable tool for measuring friction on cycleways. Different winter road conditions, as well as different pavement materials, can be distinguished from each other through PFT measurements. The PFT provides a good complement to visual inspections of cycleways in. winter maintenance evaluation and can, for example, be used to determine if desired service levels have been achieved.

  • 8598. Bergstrom, J
    et al.
    Murphy, C
    Eulitz, M
    Weiss, DT
    Westermark, Gunilla
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Cell Biology.
    Solomon, A
    Westermark, P
    An additional apolipoprotein in ATTR-amyloid2001In: Amyloid: Journal of Protein Folding Disorders, ISSN 1350-6129, Vol. 8, 32-33 p.Conference paper (Other academic)
  • 8599.
    Bergstrom, Jan
    et al.
    Karolinska Institute.
    Andersson, Gerhard
    Linköping University, Department of Behavioural Sciences and Learning, Clinical and Social Psychology. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Andreas
    Mid Sweden University.
    Andreewitch, Sergej
    Karolinska Institute.
    Ruck, Christian
    Karolinska Institute.
    Carlbring , Per
    Karolinska Institute.
    An open study of the effectiveness of Internet treatment for panic disorder delivered in a psychiatric setting2009In: Nordic Journal of Psychiatry, ISSN 0803-9488, Vol. 63, no 1, 44-50 p.Article in journal (Refereed)
    Abstract [en]

    Panic disorder with or without agoraphobia (PD/A) is common and can be treated effectively with selective serotonin reuptake inhibitor (SSRI) medication or cognitive-behaviour therapy (CBT). However, the lack of access to CBT services has motivated the development of self-help approaches requiring less therapist contact. A novel treatment modality in this field, showing efficacy in several randomized trials but until now not evaluated within the context of regular psychiatric care, is Internet-based treatment. The aim of the present study was to evaluate the effectiveness of Internet-based CBT for patients in a psychiatric setting. Twenty consecutively referred patients with PD were included in the study. A structured clinical interview with a psychiatrist was conducted for inclusion, as well as at post-treatment and at the 6-month follow-up. The treatment consisted of a 10-week CBT-based self-help programme, including minimal therapist support by e-mail. At post-treatment, 94% of patients no longer met DSM-IV criteria for PD (82% at 6-month follow-up). The within-group effect sizes (for the main outcome PDSS; Panic Disorder Severity Scale) were Cohens d=2.5 (pre- to post-treatment) and 2.8 (pre-treatment to follow-up), respectively. The proportion of responders on the PDSS was 75% at post-treatment and 70% at 6-month follow-up. The results supports earlier efficacy data on Internet-based CBT for PD and indicates that it is effective also within a regular psychiatric setting. However, a larger randomized controlled trial should be conducted, directly comparing Internet-based CBT with traditionally administered CBT within such a setting.

  • 8600.
    Bergstrom, Jan
    et al.
    Karolinska Institute.
    Andersson, Gerhard
    Linköping University, Department of Behavioural Sciences and Learning, Clinical and Social Psychology. Linköping University, Faculty of Arts and Sciences.
    Ljotsson, Brjann
    Karolinska Institute.
    Ruck, Christian
    Karolinska Institute.
    Andreewitch, Sergej
    Karolinska Institute.
    Karlsson, Andreas
    Mid Sweden University.
    Carlbring, Per
    Umea University.
    Andersson, Erik
    Karolinska Institute.
    Lindefors, Nils
    Karolinska Institute.
    Internet-versus group-administered cognitive behaviour therapy for panic disorder in a psychiatric setting: a randomised trial2010In: BMC PSYCHIATRY, ISSN 1471-244X, Vol. 10, no 54Article in journal (Refereed)
    Abstract [en]

    Background: Internet administered cognitive behaviour therapy (CBT) is a promising new way to deliver psychological treatment, but its effectiveness in regular care settings and in relation to more traditional CBT group treatment has not yet been determined. The primary aim of this study was to compare the effectiveness of Internet- and group administered CBT for panic disorder (with or without agoraphobia) in a randomised trial within a regular psychiatric care setting. The second aim of the study was to establish the cost-effectiveness of these interventions. Methods: Patients referred for treatment by their physician, or self-referred, were telephone-screened by a psychiatric nurse. Patients fulfilling screening criteria underwent an in-person structured clinical interview carried out by a psychiatrist. A total of 113 consecutive patients were then randomly assigned to 10 weeks of either guided Internet delivered CBT (n = 53) or group CBT (n = 60). After treatment, and at a 6-month follow-up, patients were again assessed by the psychiatrist, blind to treatment condition. Results: Immediately after randomization 9 patients dropped out, leaving 104 patients who started treatment. Patients in both treatment conditions showed significant improvement on the main outcome measure, the Panic Disorder Severity Scale (PDSS) after treatment. For the Internet treatment the within-group effect size (pre-post) on the PDSS was Cohens d = 1.73, and for the group treatment it was d = 1.63. Between group effect sizes were low and treatment effects were maintained at 6-months follow-up. We found no statistically significant differences between the two treatment conditions using a mixed models approach to account for missing data. Group CBT utilised considerably more therapist time than did Internet CBT. Defining effect as proportion of PDSS responders, the cost-effectiveness analysis concerning therapist time showed that Internet treatment had superior cost-effectiveness ratios in relation to group treatment both at post-treatment and follow-up. Conclusions: This study provides support for the effectiveness of Internet CBT in a psychiatric setting for patients with panic disorder, and suggests that it is equally effective as the more widely used group administered CBT in reducing panic-and agoraphobic symptoms, as well as being more cost effective with respect to therapist time.

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