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  • 100901.
    Ölvingson, Christina
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hallberg, Niklas
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Timpka, Toomas
    Linköping University, Department of Computer and Information Science. Linköping University, Department of Department of Health and Society. Linköping University, The Institute of Technology.
    Prerequisites to use information system as support in Public Health Programs: an initial requirements elicitation and analysis for WHO safe sommunitiesManuscript (preprint) (Other academic)
    Abstract [en]

    The public health context constitutes a heterogeneous environment and presents a complex task for system developers. In this study, the requirements elicitation and analysis of prerequisites for using information systems (ISs) in public health programs is investigated. Special interest is also paid to geographical information system (GIS) functionality. The specific objective of this study is to explore the need for support of ISs and GISs that exists in WHO Safe Communities in Sweden. To elicit the requirements, a questionnaire based on the critical incident technique (CIT) was used. By using CIT, it is possible to focus the development on the problems experienced by the users. Moreover, it covers both technical and social requirements. Thereafter a voice of the customer table is used to transform the needs to technical requirements. The study results in recommendations for ISs development with GIS functionality for public health practitioners.

  • 100902.
    Ölvingson, Christina
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hallberg, Niklas
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Timpka, Toomas
    Linköping University, Department of Department of Health and Society. Linköping University, Faculty of Health Sciences.
    Greenes, RA
    Adaptation of the critical incident technique to requirements engineering in public health2001In: Studies in Health Technology and Informatics, ISSN 0926-9630, E-ISSN 1879-8365, Vol. 84, no 2, p. 1180-1184Article in journal (Refereed)
    Abstract [en]

    The introduction of modern information systems in public health provides new possibilities for improvements in public health services and hence also of population's health. However, development of information systems that truly supports public health practices requires that technical, cognitive, and social issues be taken into consideration. In requirements engineering for public health, a notable problem is that of capturing all aspects of the future user's voices, i.e., the viewpoints of different public health practitioners. Failing to capture these voices will result in inefficient or even useless systems. The aim of this paper is to report a requirements-engineering instrument to describe problems in the daily work of public health professionals. The issues of concern thus captured can be used as the basis for formulating the requirements of information systems for public health professionals.

  • 100903.
    Ölvingson, Christina
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hallberg, Niklas
    Linköping University, Department of Computer and Information Science. Linköping University, Department of Department of Health and Society. Linköping University, The Institute of Technology.
    Timpka, Toomas
    Linköping University, Department of Computer and Information Science. Linköping University, Department of Department of Health and Society. Linköping University, The Institute of Technology.
    Greenes, Robert A.
    Decision Systems Group, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA.
    Using the critical incident technique to define a minimal data set for requirements elicitation in public health2002In: International Journal of Medical Informatics, ISSN 1386-5056, E-ISSN 1872-8243, Vol. 68, no 1-3, p. 165-174Article in journal (Refereed)
    Abstract [en]

    The introduction of computer-based information systems (ISs) in public health provides enhanced possibilities for service improvements and hence also for improvement of the population's health. Not least, new communication systems can help in the socialization and integration process needed between the different professions and geographical regions. Therefore, development of ISs that truly support public health practices require that technical, cognitive, and social issues be taken into consideration. A notable problem is to capture ‘voices’ of all potential users, i.e., the viewpoints of different public health practitioners. Failing to capture these voices will result in inefficient or even useless systems. The aim of this study is to develop a minimal data set for capturing users' voices on problems experienced by public health professionals in their daily work and opinions about how these problems can be solved. The issues of concern thus captured can be used both as the basis for formulating the requirements of ISs for public health professionals and to create an understanding of the use context. Further, the data can help in directing the design to the features most important for the users.

  • 100904.
    Ölvingson, Christina
    et al.
    Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems. Linköping University, The Institute of Technology.
    Hallberg, Niklas
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Timpka, Toomas
    Linköping University, Department of Medicine and Health Sciences, Division of Preventive and Social Medicine and Public Health Science. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Public Health Sciences.
    Lindqvist, Kent
    Linköping University, Department of Medicine and Health Sciences, Division of Preventive and Social Medicine and Public Health Science. Linköping University, Faculty of Health Sciences.
    Ethical issues in public health projects: Implications of geographic information resolution2002In: Alvarez I:, Ward Bynum T., Àlvaro de Assis Lopes J., and Rogerson S. Proceedings of the sixth international conference: The transformation of organisations in the information Age: Social and ethical implications. ETHICOMP 2002, 2002Conference paper (Refereed)
  • 100905.
    Ölvingson, Christina
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hallberg, Niklas
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Timpka, Toomas
    Linköping University, Department of Computer and Information Science. Linköping University, Department of Department of Health and Society. Linköping University, The Institute of Technology.
    Lindqvist, Kent
    Linköping University, Department of Computer and Information Science. Linköping University, Department of Department of Health and Society. Linköping University, The Institute of Technology.
    Requirements Engineering for inter-organizational health information systems with functions for spatial analyses: modeling a WHO safe community applying Use Case Maps2002In: Methods of Information in Medicine, ISSN 0026-1270, Vol. 41, no 4, p. 299-304Article in journal (Refereed)
    Abstract [en]

    Objectives: To evaluate Use Case Maps (UCMs) as a technique for Requirements Engineering (RE) in the development of information systems with functions for spatial analyses in inter-organizational public health settings.

    Methods: In this study, Participatory Action Research (PAR) is used to explore the UCM notation for requirements elicitation and to gather the opinions of the users. The Delphi technique is used to reach consensus in the construction of UCMs.

    Results: The results show that UCMs can provide a visualization of the system's functionality and in combination with PAR provide a sound basis for gathering requirements in inter-organizational settings. UCMs were found to represent a suitable level for describing the organization and the dynamic flux of information including spatial resolution to all stakeholders. Moreover, by using PAR, the voices of the users and their tacit knowledge is intercepted. Further, UCMs are found useful in generating intuitive requirements by the creation of use cases.

    Conclusions: With UCMs and PAR it is possible to study the effects of design changes in the general information display and the spatial resolution in the same context. Both requirements on the information system in general and the functions for spatial analyses are possible to elicit when identifying the different responsibilities and the demands on spatial resolution associated to the actions of each administrative unit. However, the development process of UCM is not well documented and needs further investigation and formulation of guidelines.

  • 100906.
    Öman, Andreas
    Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    CO2-utsläpp och konsumtion: Förutsättningar för att påvisa och minska indirekta CO2-utsläpp i den enskilde individens konsumtion av varor2008Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [sv]

    IVL Svenska Miljöinstitutet utvecklade år 2001 – 2002 i projektet “Klimat.nu – Den stora miljöutmaningen”, ett webbaserat verktyg för att upplysa och vägleda individen i klimatfrågan. Verktygets syfte är att kvantifiera fossila koldioxidutsläpp som en konsekvens av individens energikonsumtion; hushållsel, drivmedel m.m. Syftet är även att individen ges råd om hur man minskar CO2-utsläpp genom att förändra sitt leverne. IVL Svenska Miljöinstitutet vill utöka beräkningsverktygets innehåll till att även omfatta konsumentvaror. Studien har sökt svar hur enskilda individers olika typer av varukonsumtion sättas i samband med CO2-utsläpp och vilka konsumentråd är rimliga att ge för att uppnå utsläppsminskningar, samt hur dessa minskningar kan kvantifieras.

    I studien har ett systemanalytiskt tillvägagångssätt tillämpats och empirin har bestått av miljöexpanderad input-output-data (MIOA). Data har samlats in från Statistiska Centralbyrån (SCB) på miljöräkenskapernas data- och analyssidor. Insamlad data beskriver utsläpp som sker i varors livscykel till och med distribution till affär (indirekta utsläpp). Det är dock viktigt att ha varuklassers hela livscykel i åtanke så att försök till att minska konsumentens indirekta CO2-utsläpp inte leder till ökade totala utsläpp. Dataosäkerheter har identifierats, vilka visar att insamlad data underskattar varors indirekta CO2-utsläpp. Data grundar sig på antagandet att Sverige skulle ha producerat alla varor som importeras. I genomsnitt är ca 69 % av varors indirekta CO2-utsläpp av utländsk härkomst, dessa länder har vanligtvis högre utsläppsintensitet än Sverige i sina produktionsstrukturer. I Sverige finns data endast tillgänglig med ca tre års fördröjning. I sin nuvarande form representerar data trots osäkerheter en lägsta nivå på olika varuklassers indirekta CO2-utsläpp.

    För att göra insamlad data funktionell i beräkningsverktyget prövades en metodik där utsläppsintensiteter beräknades. Utsläppsintensiteter tillgodoser kravet för att enskilda individers olika typer av varukonsumtion ska kunna kopplas till dess CO2-utsläpp. I beräkningsverktyget innebär det att utsläppsintensiteter integreras, som tillsammans med en viss summa pengar, utgör underlaget för att beräkna individens indirekta CO2-utsläpp. Ur ett individperspektiv är metodiken särskilt tilltalande eftersom pengar används som beräkningsenhet, enheten är något som individen oftast har lätt att relatera till. Användningen av utsläppsintensiteter möjliggör kvantifiering av en utsläppsminskning om individen spenderar en summa pengar på en varuklass med lägre utsläppsintensitet i stället en med högre. Med pengar som enhet kan även ”rebound-effekten” undvikas.

    På grund av osäkerheter i dataunderlaget kan studien inte påvisa att förändrad konsumtion av varor leder till en faktisk utsläppsminskning. Störst sannolikhet att uppnå en faktisk minskning är dock om individen råds att fördela en summa pengar från en varuklass till en annan, i vilka det finns stora kvantitativa skillnader mellan utsläppsintensiteterna.

  • 100907.
    Öman, Michael
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Optimization and Robustness of Structural Product Families2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns structural optimization and robustness evaluations, and new methods are presented that considerably reduce the computational cost of these evaluations.

    Optimization is an effective tool in the design process and the interest from industry of its usage is quickly increasing. However, the usage would probably have grown faster if the required number of computationally costly finite element analyses could be reduced. Especially in the case of product family optimization, the problem size can easily get too large to be solved within a reasonable time. This is sometimes also true for robustness evaluations. To enable the usage of optimization and robustness evaluations also for large scale industrial problems, two new methods are here presented, which require a considerably smaller number of finite element analyses.

    The first method concerns structural optimization of product families subjected to multiple crash load cases. Here, the number of required finite element analyses are considerably reduced by only considering the critical constraint in each iteration step.

    The second method is an approach to approximate the variable sensibility based on the distribution of internal energy in a structure. The method can be used to evaluate the relative robustness of different design proposals or for structural optimization. Since the method is independent of the number of parameters and design variables the computational cost of such evaluations is drastically reduced for computationally large problems.

    List of papers
    1. Finite element based robustness study of a truck cab subjected to impact loading
    Open this publication in new window or tab >>Finite element based robustness study of a truck cab subjected to impact loading
    2009 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 14, no 2, p. 111-124Article in journal (Refereed) Published
    Abstract [en]

    Optimised designs have a tendency of being sensitive to variations. It is therefore of great importance to analyse this sensitivity to assure that a design is robust, i.e. sufficiently insensitive to variations. To analyse robustness, variations are introduced in model parameters and their influences on simulation responses are studied. This is usually achieved using the Monte Carlo method. Though, due to the large number of simulations needed, the Monte Carlo method is very costly for problems requiring a long computing time. Therefore, in this work a meta model-based Monte Carlo method is used to evaluate the robustness of a vehicle structure. That is, the Monte Carlo analysis is performed on a surface approximation of the true response, over the domain of interest. The methodology used is to first identify the variables that influence the response the most, referred to as a screening, using simple linear response surfaces. This is followed by a more detailed sensitivity analysis using only the identified variables and a quadratic response surface, thereby incorporating second order effects. A truck cab model exposed to a pendulum impact load is used as an evaluation of this method, and the important variables and their influence on the response are identified. The effect of including results from forming simulations is also evaluated using the truck cab model. Variations are introduced before forming simulations, thereby taking forming effects into account in the sensitivity analysis. The method was found to be a good tool to identify important dispersion variables and to give an approximate result of the total dispersion, all with a reasonable amount of simulations.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2009
    Keywords
    Monte Carlo, meta model, robust design, response surface method, sensitivity analysis, robustness
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:liu:diva-15474 (URN)10.1080/13588260802412992 (DOI)
    Projects
    ROBDES
    Note
    On the day of the defence date the status of this article was: Accepted.Available from: 2008-11-11 Created: 2008-11-11 Last updated: 2017-12-14Bibliographically approved
    2. Structural optimization of product families subjected to multiple crash load cases
    Open this publication in new window or tab >>Structural optimization of product families subjected to multiple crash load cases
    2010 (English)In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 41, no 5, p. 797-815Article in journal (Refereed) Published
    Abstract [en]

    This paper discusses the problem of structural optimization of product families subjected to multiple load cases, evaluated by computationally costly finite element analysis. Product families generally have a complex composition of shared components that makes individual product optimization difficult as the relation between the shared variables is not always intuitive. More optimal is to treat the problem as a product family optimization problem. Though, for product families subjected to multiple and computationally costly crash loads, the optimization problem takes too long time to solve with traditional methods. Therefore, a new optimization algorithm is presented that decomposes the family problem into sub-problems and iteratively reduces the number of sub-problems, decouple and solve them. The algorithm is applicable for module based product families with predefined composition of generalized commonality, subjected to multiple load cases that can be analyzed separately. The problem reduction is performed by only considering the constraints that are critical in the optimal solution. Therefore the optimization algorithm is called the Critical Constraint Method, CCM. Finally the CCM algorithm is evaluated by two product family optimization problems.

    Place, publisher, year, edition, pages
    Springer Science Business Media, 2010
    Keywords
    Product family optimization, Multiple crash loads, Nonlinear systems, Response surface methodology, Meta model approximations, Critical constraints
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-54846 (URN)10.1007/s00158-009-0471-4 (DOI)000276075900011 ()
    Available from: 2010-04-16 Created: 2010-04-16 Last updated: 2017-12-12Bibliographically approved
    3. An improved critical constraint method for structural optimization of product families
    Open this publication in new window or tab >>An improved critical constraint method for structural optimization of product families
    2012 (English)In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 45, no 2, p. 235-246Article in journal (Refereed) Published
    Abstract [en]

    This paper discusses important improvements in the efficient Critical Constraint Method (CCM) for the optimization of structural product families subjected to multiple crash load cases. The method was first presented by Öman and Nilsson (Struct Multidisc Optim 41(5):797–815, 2010). However, the algorithm often converged towards an infeasible solution, which considerably limited the applicability of the method. Therefore, improvements are presented here to make the method more robust regarding feasible solutions, resulting in only a minor decrease in efficiency compared to the original method. The improvements include; a penalty approach to control the feasibility of the method by continuously pushing the solution out of the infeasible region, a dynamic contraction algorithm to increase the accuracy and robustness of the method by considering the optimization progress and variable history in the reduction of the step size, and the implementation of a parallel approach to further increase the efficiency of the method by enabling the full potential of large-scale computer clusters. Finally, the potential of the improved CCM algorithm is demonstrated on a large-scale industrial family optimization problem and it is concluded that the high efficiency of the method enables the usage of large product family optimization in the design process.

    Place, publisher, year, edition, pages
    Springer-Verlag, 2012
    Keywords
    Product family optimization – Multiple crash loads – Nonlinear systems – Response surface methodology – Meta model approximations – Critical constraints
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-70787 (URN)10.1007/s00158-011-0689-9 (DOI)000298500500006 ()
    Available from: 2011-09-19 Created: 2011-09-19 Last updated: 2017-12-08Bibliographically approved
    4. Evaluation of structural robustness basedon internal energy distribution
    Open this publication in new window or tab >>Evaluation of structural robustness basedon internal energy distribution
    2011 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Robustness evaluations give valuable information about the sensitivity of a structure to stochastic variation of design parameters, but are in general expensive to perform due to the extensive number of function evaluations required. Therefore, an Internal Energy Based (IEB) method is presented here, in which the structural sensitivity to variation of each thickness parameter is estimated based on the internal energy distribution obtained from one single function evaluation. In this way, the cost of such structural robustness evaluations is significantly reduced. However, the accuracy of the IEB method depends on the structural behaviour. Here it is tested for two structures with nonlinear displacement responses caused by impact loads. The method is however believed to be applicable to any structure exposed to a single load acting on a limited area of the structure, and for response functions related to the displacement of the loaded area.

    Keywords
    Robustness evaluations, Internal energy based gradients, Internal energy distribution, Internal energy based method, Structural robustness
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-70788 (URN)
    Available from: 2011-09-19 Created: 2011-09-19 Last updated: 2011-09-19Bibliographically approved
    5. Structural optimization based on internal energy distribution
    Open this publication in new window or tab >>Structural optimization based on internal energy distribution
    2011 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Structural optimization is a valuable tool to improve the performance of products, but it is in general expensive to perform due to the required extensive number of function evaluations. Therefore, an approximate method based on the internal energy distribution, which only requires a small number of function evaluations, is presented here. By this method, structural optimization can be enabled already in the initial steps in the design of new products when fast, but not necessarily precise, results are often desired. However, the accuracy of the approximate solution depends on the structural behaviour. The internal energy based optimization method is here validated for three structures, but it is believed to be applicable to any structure subjected to a single load where the functions considered are related to the displacement of the loaded area and/or the material thicknesses of the structural parts.

    Keywords
    Structural Optimization, Internal Energy Gradients, Internal Energy Based Method, Internal Energy Distribution, Product Family Optimization
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-70789 (URN)
    Available from: 2011-09-19 Created: 2011-09-19 Last updated: 2011-09-19Bibliographically approved
  • 100908.
    Öman, Michael
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Optimization and robustness of structural product families2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns structural optimization of product families and robustness. The overall objective is to find a method for performing structural optimization of product families subjected to multiple crash load cases and to ensure a robust behavior.

    A product family is a family of products where every product variant, or family member, shares at least one component with at least one other product in the family. Structural optimization of such a family is complex and for expensive function evaluations, e.g. crash simulations, the computing time to solve the problem with traditional methods gets unrealistically long. Therefore, a new optimization algorithm for product families is presented, called the critical constraint method (CCM), that reduces the number of required evaluations by only considering the active constraints in the optimal solution.

    Traditionally optimized structures have a tendency of being sensitive to small variations in the design or loading conditions. As these kind of variations are inevitable, it is important to account for this sensitivity in the design process to ensure the robustness of the optimized design.

    The thesis is divided in two parts. The first part serves as a theoretical background to the second part, the two appended articles. This first part includes introductions to the concepts of product families, optimization, meta modeling and robust design.

    The first appended paper presents a new optimization algorithm for product families subjected to multiple crash loads. The method is compared to traditional methods and tested on two smaller product family examples.

    The second paper is an application of an existing sensitivity analysis method on a large industrial application example. A sensitivity analysis is performed on a Scania truck cab subjected to an impact load in order to identify the most  influencing variables on the crash responses.

    List of papers
    1. Structural optimization of product families subjected to multiple crash load cases
    Open this publication in new window or tab >>Structural optimization of product families subjected to multiple crash load cases
    2010 (English)In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 41, no 5, p. 797-815Article in journal (Refereed) Published
    Abstract [en]

    This paper discusses the problem of structural optimization of product families subjected to multiple load cases, evaluated by computationally costly finite element analysis. Product families generally have a complex composition of shared components that makes individual product optimization difficult as the relation between the shared variables is not always intuitive. More optimal is to treat the problem as a product family optimization problem. Though, for product families subjected to multiple and computationally costly crash loads, the optimization problem takes too long time to solve with traditional methods. Therefore, a new optimization algorithm is presented that decomposes the family problem into sub-problems and iteratively reduces the number of sub-problems, decouple and solve them. The algorithm is applicable for module based product families with predefined composition of generalized commonality, subjected to multiple load cases that can be analyzed separately. The problem reduction is performed by only considering the constraints that are critical in the optimal solution. Therefore the optimization algorithm is called the Critical Constraint Method, CCM. Finally the CCM algorithm is evaluated by two product family optimization problems.

    Place, publisher, year, edition, pages
    Springer Science Business Media, 2010
    Keywords
    Product family optimization, Multiple crash loads, Nonlinear systems, Response surface methodology, Meta model approximations, Critical constraints
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-54846 (URN)10.1007/s00158-009-0471-4 (DOI)000276075900011 ()
    Available from: 2010-04-16 Created: 2010-04-16 Last updated: 2017-12-12Bibliographically approved
    2. Finite element based robustness study of a truck cab subjected to impact loading
    Open this publication in new window or tab >>Finite element based robustness study of a truck cab subjected to impact loading
    2009 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 14, no 2, p. 111-124Article in journal (Refereed) Published
    Abstract [en]

    Optimised designs have a tendency of being sensitive to variations. It is therefore of great importance to analyse this sensitivity to assure that a design is robust, i.e. sufficiently insensitive to variations. To analyse robustness, variations are introduced in model parameters and their influences on simulation responses are studied. This is usually achieved using the Monte Carlo method. Though, due to the large number of simulations needed, the Monte Carlo method is very costly for problems requiring a long computing time. Therefore, in this work a meta model-based Monte Carlo method is used to evaluate the robustness of a vehicle structure. That is, the Monte Carlo analysis is performed on a surface approximation of the true response, over the domain of interest. The methodology used is to first identify the variables that influence the response the most, referred to as a screening, using simple linear response surfaces. This is followed by a more detailed sensitivity analysis using only the identified variables and a quadratic response surface, thereby incorporating second order effects. A truck cab model exposed to a pendulum impact load is used as an evaluation of this method, and the important variables and their influence on the response are identified. The effect of including results from forming simulations is also evaluated using the truck cab model. Variations are introduced before forming simulations, thereby taking forming effects into account in the sensitivity analysis. The method was found to be a good tool to identify important dispersion variables and to give an approximate result of the total dispersion, all with a reasonable amount of simulations.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2009
    Keywords
    Monte Carlo, meta model, robust design, response surface method, sensitivity analysis, robustness
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:liu:diva-15474 (URN)10.1080/13588260802412992 (DOI)
    Projects
    ROBDES
    Note
    On the day of the defence date the status of this article was: Accepted.Available from: 2008-11-11 Created: 2008-11-11 Last updated: 2017-12-14Bibliographically approved
  • 100909.
    Öman, Michael
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Asadi Rad, Nima
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Nilsson, Larsgunnar
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Evaluation of structural robustness basedon internal energy distribution2011Manuscript (preprint) (Other academic)
    Abstract [en]

    Robustness evaluations give valuable information about the sensitivity of a structure to stochastic variation of design parameters, but are in general expensive to perform due to the extensive number of function evaluations required. Therefore, an Internal Energy Based (IEB) method is presented here, in which the structural sensitivity to variation of each thickness parameter is estimated based on the internal energy distribution obtained from one single function evaluation. In this way, the cost of such structural robustness evaluations is significantly reduced. However, the accuracy of the IEB method depends on the structural behaviour. Here it is tested for two structures with nonlinear displacement responses caused by impact loads. The method is however believed to be applicable to any structure exposed to a single load acting on a limited area of the structure, and for response functions related to the displacement of the loaded area.

  • 100910.
    Öman, Michael
    et al.
    Scania CV AB, Södertälje.
    Nilsson, Larsgunnar
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    An improved critical constraint method for structural optimization of product families2012In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 45, no 2, p. 235-246Article in journal (Refereed)
    Abstract [en]

    This paper discusses important improvements in the efficient Critical Constraint Method (CCM) for the optimization of structural product families subjected to multiple crash load cases. The method was first presented by Öman and Nilsson (Struct Multidisc Optim 41(5):797–815, 2010). However, the algorithm often converged towards an infeasible solution, which considerably limited the applicability of the method. Therefore, improvements are presented here to make the method more robust regarding feasible solutions, resulting in only a minor decrease in efficiency compared to the original method. The improvements include; a penalty approach to control the feasibility of the method by continuously pushing the solution out of the infeasible region, a dynamic contraction algorithm to increase the accuracy and robustness of the method by considering the optimization progress and variable history in the reduction of the step size, and the implementation of a parallel approach to further increase the efficiency of the method by enabling the full potential of large-scale computer clusters. Finally, the potential of the improved CCM algorithm is demonstrated on a large-scale industrial family optimization problem and it is concluded that the high efficiency of the method enables the usage of large product family optimization in the design process.

  • 100911.
    Öman, Michael
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Nilsson, Larsgunnar
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Structural optimization based on internal energy distribution2011Manuscript (preprint) (Other academic)
    Abstract [en]

    Structural optimization is a valuable tool to improve the performance of products, but it is in general expensive to perform due to the required extensive number of function evaluations. Therefore, an approximate method based on the internal energy distribution, which only requires a small number of function evaluations, is presented here. By this method, structural optimization can be enabled already in the initial steps in the design of new products when fast, but not necessarily precise, results are often desired. However, the accuracy of the approximate solution depends on the structural behaviour. The internal energy based optimization method is here validated for three structures, but it is believed to be applicable to any structure subjected to a single load where the functions considered are related to the displacement of the loaded area and/or the material thicknesses of the structural parts.

  • 100912.
    Öman, Michael
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Nilsson, Larsgunnar
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Structural optimization of product families subjected to multiple crash load cases2010In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 41, no 5, p. 797-815Article in journal (Refereed)
    Abstract [en]

    This paper discusses the problem of structural optimization of product families subjected to multiple load cases, evaluated by computationally costly finite element analysis. Product families generally have a complex composition of shared components that makes individual product optimization difficult as the relation between the shared variables is not always intuitive. More optimal is to treat the problem as a product family optimization problem. Though, for product families subjected to multiple and computationally costly crash loads, the optimization problem takes too long time to solve with traditional methods. Therefore, a new optimization algorithm is presented that decomposes the family problem into sub-problems and iteratively reduces the number of sub-problems, decouple and solve them. The algorithm is applicable for module based product families with predefined composition of generalized commonality, subjected to multiple load cases that can be analyzed separately. The problem reduction is performed by only considering the constraints that are critical in the optimal solution. Therefore the optimization algorithm is called the Critical Constraint Method, CCM. Finally the CCM algorithm is evaluated by two product family optimization problems.

  • 100913.
    Önnegren, Anna
    Linköping University, Department of Electrical Engineering.
    Feldetektering för diagnos med differentialgeometriska metoder -en implementering i Mathematica2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Diagnosis means detection and isolation of faults. A model based diagnosis system is built on a mathematical model of the system. The difficulty when constructing the diagnosis system depends om how the model is formulated. In this report, a method is described that rewrites the model on such a form that the construction of the diagnosis algoritm is easy. The model is transformed by two state space transformations and the result will be a system on state space form where one part of the system becomes easy to supervise.

    The main part of the report describes the procedure to create these transformations, which can be done in seven steps, based on differential geometric methods.

    The aim of this masters thesis was to create an implementation in Mathematica (a computer tool for symbolic formula manipulation) of the creation of the two transformations and the system transformation. The created functions are described and examples of these are given.

    A further aim was to evaluate if Mathematica could be a good support to rewrit a model. This was done by studying examples, and on the basis of the examples, identify difficult and easy steps.

    The program has shown to be a good aid. Two of the seven steps have been identified as difficult and proposals for improvements have been given.

  • 100914.
    Öquist, Mats
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Northern peatland carbon biogeochemistry: the influence of vascular plants and edaphic factors on carbon dioxide and methane exchange2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The interest in carbon dynamics and the interactions between ecosystems and the atmosphere has increased during the last decade due to the postulated threat of anthropgenically induced global and climate change. Northern peatlands, with their large stores of organic carbon and long-term net accumulation of atmospheric carbon dioxide are key ecosystems in these interactions. Furthermore, peatlands transform organic carbon to methane, which also is an important greenhouse gas.

    The findings reported in this thesis and in the accompanying papers are based on both laboratory and field investigations of carbon transformation dynamics on the process scale and at the resolution of individual peatland plant communities. The data from one of the studies also is extrapolated in an attempt to identify environmental controls on regional scales in order to predict the response of northern pcatlands to climate warming.

    The laboratory experiments focus on how climate variations, inducing fluctuations in groundwater level and also soil freeze-thaw cycles, influences organic matter mineralisation to carbon dioxide and methane. The field studies investigate year-to-year variations and interdecadal differences in carbon gas exchange at a subarctic peatland, and also how the physiological activities of vascular plants control methane emission rates.

    The main conclusions presented include:

    Soil freeze-thaw events may be very important for the annual carbon balance in northern peatlands, because they have the potential to increase mineralisation rates and alter biogeochemical degradation pathways.

    Vascular plants exert a strong influence on methane flux dynamics during the growing season, both by mediating methane transport and through substrate-based interactions with the soil microbial community. However, there are important species-related factors that govern the nature and extent of this influence.

    Caution has to be taken when extrapolating field data to estimate regional carbon exchange because the relevance of the specific environmental parameters that control this exchange varies depending on resolution. On broad spatial and temporal scales the best predictor of peatland methane emissions is mean soil temperature, but also microbial substrate availability (expressed as the organic acid concentration in peat water) is of importance. This temperature sensitivity represents a strong potential feedback mechanism on climate change.

    List of papers
    1. Effects of a transient oxic period on mineralization of organic matter to CH4 and CO2 in anoxic peat incubations
    Open this publication in new window or tab >>Effects of a transient oxic period on mineralization of organic matter to CH4 and CO2 in anoxic peat incubations
    1998 (English)In: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 15, no 4, p. 325-333Article in journal (Refereed) Published
    Abstract [en]

    Rates of organic matter mineralization in peatlands, and hence production of the greenhouse gases CH4 and CO2, are highly dependent on the distribution of oxygen in the peat. Using laboratory incubations of peat, we investigated the sensitivity of the anoxic production of CH4 and CO2 to a transient oxic period of a few weeks’ duration. Production rates during 3 successive anoxic periods were compared with rates in samples incubated in the presence of oxygen during the second period. In surface peat (5–10‐cm depth), with an initially high level of CH4 production, oxic conditions during period 2 did not result in a lower potential CH4 production rate during period 3, although production was delayed 1 week. In permanently anoxic, deep peat (50–55‐cm depth) with a comparatively low initial production of CH4, oxic conditions during period 2 resulted in zero production of CH4 during period 3. Thus, the methanogens in surface peal—but not in deep peat—remained viable after several weeks of oxic conditions. In contrast to CH4 production, the oxic period had a negligible effect on anoxic CO2 production during period 3, in surface as well as deep peat. In both surface and deep peat, CO2 production was several times higher under oxic than under anoxic conditions. However, for the first 2 weeks of oxic conditions, CO2 production in the deep peat was very low. Still, deep peat obviously contained facultative microorganisms that, after a relatively short period, were able to maintain a considerably higher rate of organic matter mineralization under oxic than under anoxic conditions.

    Keywords
    carbon dioxide production, methane production, mineralization, oxygen tolerance, peatland, Sphagnum peat
    National Category
    Social Sciences Interdisciplinary
    Identifiers
    urn:nbn:se:liu:diva-79154 (URN)10.1080/01490459809378086 (DOI)
    Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2018-01-12Bibliographically approved
    2. Effects of freeze-thaw cycles on low temperature carbon mineralisation in peat
    Open this publication in new window or tab >>Effects of freeze-thaw cycles on low temperature carbon mineralisation in peat
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Recent investigations indicate that winter carbon emission from peatlands and low temperature carbon mineralisation processes conld have the potential to affect annual carbon budgets. Special emphasis has been put on periods of freeze-thaw events during spring and autumn. The aim of this study was to investigate the impact of freeze-thaw cycles on peat carbon mineralisation. This was addressed by following production rates and total amounts of CO,- and CH4-formation in surface (0-5 cm) and deep (45-50 cm) peat samples incubated at 4°C and comparing controls with replicate samples subjected to three consecutive freeze-thaw cyclesprior to incubation. Accumulation of fermentation products (H2, VF A and ethanol) were measured in order to gain further insight to the biogeochemical processes and transformation pathways involved. We conclude that freeze-thaw cycles affect both short and long term formation and exchange of C02 by altering the availability and amount of peat carbon substrates. Freeze-thaw events also resulted in an inhibition of methanogenesis with a concomitant accumulation in H2 and butyrate. We conclude that freezethaw cycling events can be of large importance for the carbon budgets of northern peatland ecosystems, although they are of a limited temporal duration.

    National Category
    Social Sciences Interdisciplinary
    Identifiers
    urn:nbn:se:liu:diva-79155 (URN)
    Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2018-01-12Bibliographically approved
    3. Interdecadal changes in CO2 and CH4 fluxes of subarctic mire: Stordalen revisted after 20 years
    Open this publication in new window or tab >>Interdecadal changes in CO2 and CH4 fluxes of subarctic mire: Stordalen revisted after 20 years
    1999 (English)In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 85, no 1, p. 22-30Article in journal (Refereed) Published
    Abstract [en]

    The first subarctic wetland CO2 and CH4 flux measurements were made at Stordalen in the beginning of the 1970s in connection with the IBP study. A return to this area in 1994-95 offered a unique opportunity to study possible interdecadal changes in northern wetland CO2 and CH4 emissions. Measurements of CO2 and CH4 fluxes were carried out in similar habitats as those investigated in 1974. The mire distribution of wet minerotrophic areas relative to the elevated ombrotrophic areas had changed dramatically over the twenty years. There were no significant differences between the CH4-flux in 1974, 1994, and 1995. However, the CO2 fluxes were significantly higher in 1995 than in 1974. Since differences in climatic conditions gave no cause for such a change it suggests a possible increase in decomposition rate to be due to other factors. We suggest changes in vegetation composition, altered mineralization pathways and disintegration of permafrost as causes for the interdecadal increase in decomposition rates.

    National Category
    Social Sciences Interdisciplinary
    Identifiers
    urn:nbn:se:liu:diva-33657 (URN)10.2307/3546788 (DOI)19692 (Local ID)19692 (Archive number)19692 (OAI)
    Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2018-01-13Bibliographically approved
    4. Vascular plants as regulators of methane emissions from a subarctic mire ecosystem
    Open this publication in new window or tab >>Vascular plants as regulators of methane emissions from a subarctic mire ecosystem
    2002 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 107, no 21, p. 4580-4590Article in journal (Refereed) Published
    Abstract [en]

    Vascular plant functions as controlling mechanisms of methane emissions were investigated at two contrasting habitat types at a subarctic peatland ecosystem in northern Sweden. One of the habitats was ombrotrophic (vegetation dominated by Eriophorum vaginatum and Carex rotundata), while the other was minerotrophic (vegetation dominated by Eriophorum angustifolium). Through shading manipulations we successfully reduced the gross photosynthetic rates of the vascular plant communities. At the ombrotrophic site a 25% reduction in gross photosynthesis lead to a concomitant 20% reduction in methane emission rates, indicating a strong substrate-based coupling between the vascular plant community and the methanogenic populations. At the minerotrophic site, methane emission rates were unaffected, although plant photosynthesis was reduced by almost 50%. However, the methane emission rates at the minerotrophic site were significantly correlated with the number of vascular plants. We conclude that at the minerotrophic site the vegetation influences methane emission rates by facilitating methane transportation between the soil and the atmosphere, while at the ombrotrophic site the relationship between the vascular plant community and methane emissions is mediated by substrate-based interactions regulated by plant photosynthetic activity. Copyright 2002 by the American Geophysical Union.

    Keywords
    Carbon exchange, Methane emission, Peatland biogeochemistry, Plant-microbe interactions, Vascular plants
    National Category
    Social Sciences
    Identifiers
    urn:nbn:se:liu:diva-46812 (URN)10.1029/2001JD001030 (DOI)
    Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13Bibliographically approved
    5. Large scale variations in CH4 emissions from wetlands explained by temperature and substrate availability
    Open this publication in new window or tab >>Large scale variations in CH4 emissions from wetlands explained by temperature and substrate availability
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Globally, wetlands are at estimates ranging 115-237 Tg C4/yr1 the largest single source of the greenhouse gas CH4 to the atmosphere. Important feedback mechanisms on climate change arising from changing exchanges of C02 between the terrestrial biosphere and the atmosphere have recently been identified2. A related question is how will possible changes in the CH4 emissions from wetlands affect the further development of the greenhouse effect? Here we show using comparable methods in a wide range of wetlands ranging from Greenland to Siberia that regardless the dependency on soil moisture, plant productivity and other factors, temperature is the strongest control and predictor of CH4 emissions across both temporal and large spatial scales. Furthermore, we show that CH4 flux variations not explained by temperature can beattributed to differences in microbial substrate availability (expressed as the organic acid concentration in peat water). Combined, soil temperature and organic acid concentrations explains 99% of the variation in CH4 fluxes between the different sites. The temperature sensitivity of the CH4 emissions shown suggests a strong feedback mechanism on climatechange that should valid incorporation in developments of global circulation models.

    National Category
    Social Sciences Interdisciplinary
    Identifiers
    urn:nbn:se:liu:diva-79157 (URN)
    Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2018-01-12Bibliographically approved
  • 100915.
    Öquist, Mats
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Berg, Anders
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Effects of freeze-thaw cycles on low temperature carbon mineralisation in peatManuscript (preprint) (Other academic)
    Abstract [en]

    Recent investigations indicate that winter carbon emission from peatlands and low temperature carbon mineralisation processes conld have the potential to affect annual carbon budgets. Special emphasis has been put on periods of freeze-thaw events during spring and autumn. The aim of this study was to investigate the impact of freeze-thaw cycles on peat carbon mineralisation. This was addressed by following production rates and total amounts of CO,- and CH4-formation in surface (0-5 cm) and deep (45-50 cm) peat samples incubated at 4°C and comparing controls with replicate samples subjected to three consecutive freeze-thaw cyclesprior to incubation. Accumulation of fermentation products (H2, VF A and ethanol) were measured in order to gain further insight to the biogeochemical processes and transformation pathways involved. We conclude that freeze-thaw cycles affect both short and long term formation and exchange of C02 by altering the availability and amount of peat carbon substrates. Freeze-thaw events also resulted in an inhibition of methanogenesis with a concomitant accumulation in H2 and butyrate. We conclude that freezethaw cycling events can be of large importance for the carbon budgets of northern peatland ecosystems, although they are of a limited temporal duration.

  • 100916.
    Öquist, Mats
    et al.
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Sundh, Ingvar
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Effects of a transient oxic period on mineralization of organic matter to CH4 and CO2 in anoxic peat incubations1998In: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 15, no 4, p. 325-333Article in journal (Refereed)
    Abstract [en]

    Rates of organic matter mineralization in peatlands, and hence production of the greenhouse gases CH4 and CO2, are highly dependent on the distribution of oxygen in the peat. Using laboratory incubations of peat, we investigated the sensitivity of the anoxic production of CH4 and CO2 to a transient oxic period of a few weeks’ duration. Production rates during 3 successive anoxic periods were compared with rates in samples incubated in the presence of oxygen during the second period. In surface peat (5–10‐cm depth), with an initially high level of CH4 production, oxic conditions during period 2 did not result in a lower potential CH4 production rate during period 3, although production was delayed 1 week. In permanently anoxic, deep peat (50–55‐cm depth) with a comparatively low initial production of CH4, oxic conditions during period 2 resulted in zero production of CH4 during period 3. Thus, the methanogens in surface peal—but not in deep peat—remained viable after several weeks of oxic conditions. In contrast to CH4 production, the oxic period had a negligible effect on anoxic CO2 production during period 3, in surface as well as deep peat. In both surface and deep peat, CO2 production was several times higher under oxic than under anoxic conditions. However, for the first 2 weeks of oxic conditions, CO2 production in the deep peat was very low. Still, deep peat obviously contained facultative microorganisms that, after a relatively short period, were able to maintain a considerably higher rate of organic matter mineralization under oxic than under anoxic conditions.

  • 100917.
    Öquist, Mats
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Vascular plants as regulators of methane emissions from a subarctic mire ecosystem2002In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 107, no 21, p. 4580-4590Article in journal (Refereed)
    Abstract [en]

    Vascular plant functions as controlling mechanisms of methane emissions were investigated at two contrasting habitat types at a subarctic peatland ecosystem in northern Sweden. One of the habitats was ombrotrophic (vegetation dominated by Eriophorum vaginatum and Carex rotundata), while the other was minerotrophic (vegetation dominated by Eriophorum angustifolium). Through shading manipulations we successfully reduced the gross photosynthetic rates of the vascular plant communities. At the ombrotrophic site a 25% reduction in gross photosynthesis lead to a concomitant 20% reduction in methane emission rates, indicating a strong substrate-based coupling between the vascular plant community and the methanogenic populations. At the minerotrophic site, methane emission rates were unaffected, although plant photosynthesis was reduced by almost 50%. However, the methane emission rates at the minerotrophic site were significantly correlated with the number of vascular plants. We conclude that at the minerotrophic site the vegetation influences methane emission rates by facilitating methane transportation between the soil and the atmosphere, while at the ombrotrophic site the relationship between the vascular plant community and methane emissions is mediated by substrate-based interactions regulated by plant photosynthetic activity. Copyright 2002 by the American Geophysical Union.

  • 100918.
    Öqvist, Jenny
    Linköping University, Department of Language and Culture.
    I samhörighetens tjänst. Användningen av pronomen 'han' och 'hon' i initialposition.2005In: Samtal och grammatik. Studier i svenskt samtalsspråk. / [ed] Jan Anward & Bengt Nordberg, Lund: Studentlitteratur , 2005, p. 139-156Chapter in book (Other academic)
    Abstract [sv]

    Samtalsspråkets grammatik, finns den? Frågan kan tyckas överraskande, men för de flesta människor är grammatik förknippat med skriftspråk och med skolans språkundervisning. Den traditionella grammatikforskningen har mesta-dels byggt på skriftspråket. Den här boken vill visa att också det fritt flödande, oreflekterade talet i dialoger och flerpartssamtal följer grammatiska regler, även om dessa delvis är av annan art och framsprungna ur andra praktiker än skriftspråkets.

    Syftet med boken är att beskriva strategiskt valda, återkommande grammatiska strukturer som kan bilda underlag för fortsatta talspråksgrammatiska studier. Alla studierna bygger på audio- och videoinspelningar av autentiska, spontana samtal, såväl institutionella som vardagliga, personliga.

    Detta är den första bok som på svenska presenterar det nya forskningsområdet interaktionell lingvistik för en större läsekrets. Förutom som ett inlägg i den vetenskapliga debatten, är den tänkt att användas på olika nivåer i den akademiska undervisningen i sociolingvistik, samtalsforskning och grammatik.

    Den kan också med fördel nyttiggöras inom andra ämnen, t.ex. sociologi, och ge viktiga insikter till studerande inom utbildningar till olika service- och människovårdande yrken.

  • 100919.
    Öqvist, Jenny
    Linköping University, Department of Culture and Communication. Linköping University, Faculty of Arts and Sciences.
    När man talar om trollen: Personreferens i svenskt samtalsspråk2005Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The thesis investigates reference to non-present, singular persons in Swedish talk-ininteraction. The overall aim of the study is to analyse instances of person reference as parts of their linguistic, sequential and social contexts, and to describe these instances with regard to interactional, formal/structural, and functional aspects. An important point of departure for the study is that instances of person reference must be analysed as choices from different alternatives. This means that instances of person reference should neither be thought of as mere manifestations of the speaker’s own state of knowledge of the referent and her/his assessment of the addressee’s knowledge state, nor as reflections of structural aspects of the discourse. Theoretically and methodologically, the study belongs to the fields of interactional linguistics and conversation analysis (CA). The data for the study are drawn from naturally occurring everyday and institutional interaction and includes two-party and multi-party interaction, and telephone as well as face-to-face interaction.

    The analyses of introductory references to persons highlight issues such as the speaker’s claimed knowledge of/familiarity with the referent as well as the claims being made on behalf of the addressee, the role and importance of the referent in the activity of the talk, and the implications of person reference on the affiliation/disaffiliation of the participants with the referent, as well as with each other. The analyses of references to persons that have already been introduced in the interaction centres on partly different issues. The categorization of these references is based on two factors; the first being the sequential position of the reference and the second being whether the reference contributes to sequential continuity or discontinuity. The analyses emphasize that referential choice is an important resource for the construction of continuity and discontinuity, and that participants make use of these resources in unmarked as well as marked ways. This means that participants choose between different referential expressions, and these choices have different consequences depending on, inter alia, the sequential position of the reference. The study shows that reference to persons is doubly contextual: participants’ referential choices are made in consideration of the foregoing as well as the upcoming activity of the talk. Consequently, in order to adequately describe instances of person reference, the sequential context must be taken into account.

  • 100920.
    Öqvist, Jenny
    Linköping University, Department for Studies of Social Change and Culture. Linköping University, Faculty of Arts and Sciences.
    Personreferens som socialt verktyg - en analys.2003In: Grammatik och samtal: studier till minne av Mats Eriksson / [ed] Bengt Nordberg, Uppsala: Inst. för nordiska språk, Uppsala universitet. , 2003, p. 101-111Chapter in book (Other academic)
  • 100921.
    Öqvist, Johanna
    et al.
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Bergfelt, Petra
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Nudge; en knuff i rätt riktning?: Ett beteendeekonomiskt experiment om svenskars attityder till nudge2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Behavioral interventions – so-called nudge – aim to get individuals to make decisions that are beneficial for the individual as well as for the society by making subtle changes in the decision context. Policymakers worldwide use nudge as an additional policy tool. However, nudging has been criticized for its questionable ethical principles and to date the debate concerning these issues has largely proceeded without much input from the general public. When should nudges be deemed as acceptable and when are they perceived as restrictive of an individual’s freedom of choice? Should all nudges be perceived as equal or do attitudes depend on specific characteristics of the nudge-intervention?The objective of this study is to elicit public views on the use of nudges with regard to i) acceptance and ii) restrictive on an individual’s freedom of choice. In particular, the study examines attitudes towards pro-self nudges (i.e. focusing on private welfare) and pro-social nudges (i.e. focusing on social welfare) as well as nudge of three degrees of intrusiveness (categorization of level of intrusiveness on the individual’s autonomy). In addition, we explore how individual differences in worldview affect attitudes towards nudge. A general population sample in Sweden (n=677) were presented with nudge-scenarios concerning three policy contexts; energy saving, smoking and retirement, in which they responded to questions regarding attitudes. To explore preferences towards pro-self and pro-social nudge, we used a contrastive vignette technique. To test for individual differences, measures on cultural cognition were included.The result show that all nudge-scenarios have majority support (for acceptance). However, a quarter of the nudge-scenarios were perceived as restrictive of an individual’s freedom of choice. Differences regarding attitudes towards pro-self and pro-social nudge cannot be ensured statistically. For degree of intrusiveness we found that a higher degree of intrusiveness reduces the level of acceptance for the nudge-scenarios. As for restrictive on an individual’s freedom of choice, we found the remarkable result that a medium degree of intrusiveness is perceived as less intrusive than a high degree of intrusiveness. Furthermore, we found that individuals with an individualistic worldview tend to be less accepting towards nudge-scenarios.In conclusion, our results indicate that there is no general accepted formula for how a nudge should be designed. Highlighting this is a fundamental aspect both for broadening the theory of nudge as a policy tool as well as to implement efficient nudges in the future.

  • 100922.
    Öresjö, Per
    Linköping University, Department of Electrical Engineering.
    A High Speed Sigma Delta A/D-Converter for a General Purpose RF Front End in 90nm-Technology2007Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    In this report a transistor-level design of a GHz Sigma-Delta analog-to-digital converter for an RF front end is proposed. The design is current driven, where the integration is done directly over two capacitances and it contains no operational amplifiers.

    The clock frequency used for verification was 2.5 GHz and the output band-width was 10 MHz. The system is flexible in that the number of internal bits can be scaled easily and in this report a three-bit system yielding an SNR of 76.5 dB as well as a four-bit system yielding an SNR of 82.5 dB are analyzed.

  • 100923.
    Örjeman, Johanna
    et al.
    Linköping University, Department of Behavioural Sciences and Learning.
    Hjertstedt, Lina
    Linköping University, Department of Behavioural Sciences and Learning.
    Litteratur i undervisningen, en tillgång för elevers lärande?: En litteraturstudie kring litteraturs användning i undervisningen i årskurs F-3.2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 100924.
    Örjestam, Kristoffer
    Linköping University, Department of Culture and Communication.
    Föreställningen om idealkvinnan: Det konstruerade pastorala kvinnoporträttet under frihetstiden2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    An analysis of the female constructed gender and it's display in the pastoral portrait during the first half of the 18th century in Sweden. By looking at the kontext of the time an through analyzing three portraits the matter of woman as an ideal will be explored.

  • 100925. Örlyggsson, Johan
    et al.
    Andersson, Rolf
    Svensson, Bo
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    Alanine as an end product during fermentation of monosacharides by Clostridium strain P21995In: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology, ISSN 0003-6072, E-ISSN 1572-9699, Vol. 68, p. 273-280Article in journal (Refereed)
  • 100926.
    Örn, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Szilassy, Martin
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Dil, Bram
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    A Novel Multi-Step Algorithm for Low-Energy Positioning Using GPS2016In: Fusion 2016, 19th International Conference on Information Fusion: Proceedings, 2016, p. 1469-1476Conference paper (Refereed)
    Abstract [en]

    GPS is widely used for localization and tracking, however traditional GPS receivers consume too much energy for many applications. This paper implements and evaluates the performance of a low-energy GPS prototype. The main difference is that a traditional GPS needs to sample signals transmitted by satellites for 30 seconds to estimate its position. Our prototype reduces this time by three orders of magnitude and it can compute positions from only 2 milliseconds of data. We present a new algorithm that increases robustness by filtering on estimated residuals instead of using an altitude database. In addition, we show that our new algorithm works with both fixed and moving targets. The solution consists of (1) a portable device that samples the GPS signal and (2) a server that utilizes Doppler navigation and Coarse Time Navigation to estimate positions. We performed tests in a wide variety of environments and situations. These tests show that our prototype provides a median positioning error of roughly 40 meters even when the GPS receiver is moving at 80 kilometres per hour.

  • 100927.
    Örn, Markus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Towards Better Alternator Efficiency2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The requirements on vehicle industry are constantly getting stricter, especially when it comes to emissions. At the same time cars, trucks and buses are needed for our way of living. This have forced companies to be as ecient as possible in their way of using fossil fuels for travelling and transport. To increase the eciency companies investigate all possible fuel savings to decrease their carbon footprint as much as possible. One area of savings that is not that obvious to many people is the alternator. Several percent of the total energy used by a vehicle are needed to operate the alternator. With a typical alternator eciency of 70% considerable savings can be achieved.

    This thesis that concern alternator eciency was carried out at Scania in Södertälje, Sweden. The goal of the thesis is to construct a mathematical model of an alternator. The model is supposed to consider all losses in the alternator and together with the output power give an eciency model of the alternator at different speeds and loads. A great part of the project has been dealing with the magnetic losses. The magnetic losses have been modeled as an equivalent circuit with the load angle as a central piece. The equivalent circuit is built up by the fact that the alternator used in the vehicles is a salient pole alternator. The equivalent circuit describes a voltage equation where the voltage drop over the magnetic inductance is described. From that relations between the signals in the alternator and output signals can be written.

    The alternator model is then used together with data recorded from different buses all over the world, this to be able to investigate how the alternator contributes to the fuel consump- tion depending on the way that the buses are driven.

    The result of this thesis is a mathematical model that describes the losses in the alternator for different load cases and speeds. 

  • 100928.
    Örn, Sara
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Realistic Multi-Cell Interference Coordination in 4G/LTE2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the LTE mobile system, all cells use the same set of frequencies. This means that a user could experience interference from other cells. A method that has been studied in order to reduce this interference and thereby increase data rate or system throughput is to coordinate scheduling between cells. Good results of this have been found in different studies. However, the interference is generally assumed to be known. Studies using estimated interference and simulating more than one cluster of cells have found almost no gain.

    This thesis will focus on how to use information from coordinated scheduling and other traffic estimates to do better interference estimation and link adaption. The suggested method is to coordinate larger clusters and use the coordination information, as well as estimates of which cells will be transmitting, to make estimates of interference from other cells. The additional information from interference estimation is used in the link adaptation. Limitations in bandwidth of the backhaul needed to send data between cells are considered, as well as the delay it may introduce. A limitation of the scope is that MIMO or HetNet scenarios have not been simulated.

    The suggested method for interference estimation and link adaptation have been implemented and simulated in a system simulator. The method gives a less biased estimate of SINR, but there are no gains in user bit rate. The lesser bias is since the method is better at predicting high SINR than the base estimate is. The lack of gains regarding user bit rate may result from the fact that in the studied scenarios, users where not able to make use of the higher estimated SINR since the base estimate is already high.

    The conclusion is that the method might be useful in scenarios where there are not full load, but the users either have bad channel quality or are able to make use of very high SINR. Such scenarios could be HetNet or MIMO scenarios, respectively.

  • 100929.
    Örnberg Berglund, Therese
    Linköping University, Department of Culture and Communication, Modern Languages. Linköping University, Faculty of Arts and Sciences.
    Text-based chat and language learning: opportunities and challenges2013In: Språk i undervisning: rapport från ASLA:s vårsymposium, Linköping, 11-12 maj, 2012 / [ed] Christina Rosén, Per Simfors, Ann-Kari Sundberg, Uppsala: ASLA (Institutionen för Nordiska språk, Uppsala universitet) , 2013, p. 139-149Chapter in book (Other academic)
    Abstract [en]

    The aim of the current article is to discuss opportunities and challenges with employing text-based interaction in the language classroom. These issues are addressed in relation to empirical data from a Swedish upper secoondary school, where students of English interact with a teacher (the researcher) in instant messaging. In order to gain a detailed picture of the interactional processes, data from chat logs are complemented with screen recordings, keystroke logging data and data from eye tracking. It should be noted that the current article cannot give a comprehensive account of all relevant phenomena and previous research, but rather some identified pattems will be highlighted and discussed.

  • 100930.
    Örnberg, Dennis
    Linköping University, Department of Computer and Information Science, Database and information techniques.
    Comparison and implementation of graph visualization algorithms using JavaFX2016Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Graph drawing is an important area in computer science and it has many different application areas. For example, graphs can be used to visualize structures like networks and databases. When the graphs are really big, however, it becomes difficult to draw them so that the user can get a good overview of the whole graph and all of its data. There exist a number of different algorithms that can be used to draw graphs, but they have a lot of differences. The goal of this report was to find an algorithm that produces graphs of satisfying quality in little time for the purpose of ontology engineering, and implement it using a platform that visualizes the graph using JavaFX. It is supposed to work on a visualization table with a touch display. A list of criteria for both the algorithm and the application was made to ensure that the final result would be satisfactory. A comparison between four well-known graph visualization algorithms was made and “GEM” was found to be the best suited algorithm for visualizing big graphs. The two platforms Gephi and Prefux were introduced and compared to each other, and the decision was made to implement the algorithm in Prefux since it has support for JavaFX. The algorithm was implemented and evaluated, it was found to produce visually pleasing graphs within a reasonable time frame. A modified version of the algorithm called GEM-2 was also introduced, implemented and evaluated. With GEM-2, the user can pick a specific number of levels to be expanded at first, additional levels can then be expanded by hand. This greatly improves the performance when there is no need to expand the whole graph at once, however, it also increases the amount of edge crossings which makes the graph less visually pleasing.

  • 100931.
    Örnerheim, Mattias
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, The Institute of Technology.
    Entrepreneurial actors between two systems of norms - Profound and professional quality knowledge in Swedish health care2011Conference paper (Other academic)
  • 100932.
    Örnerheim, Mattias
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, The Institute of Technology.
    Kvalitetsbegreppet i lagstiftningen inom den mänskliga sektorn: - en översikt2013Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Denna undersökning behandlar hur olika kvalitetsaspekter i några utvalda sektorslagar förhåller sig till varandra inom hälso- och sjukvård, polis- och kriminalvård, utbildning samt vissa kommunala lagar. Alla befinner sig i den s.k. mänskliga sektorn av offentlig verksamhet. Den bakomliggande orsaken till detta är att Innovationsrådet vill fördjupa kunskapen om hur begreppet kvalitet definieras och används i svensk lagstiftning och i förarbetena till vissa lagar. Undersökningen strävar inte efter att generera någon legaldefinition av begreppet kvalitet.

    Kvalitetsbegreppet delas in i aspekterna; struktur, process och resultat i en analysmodell i form av en matris som även tar hänsyn till personal och medborgarperspektiv. Strukturkvalitet speglar förutsättningarna för eller inflödet i en verksamhet, processkvalitet belyser de aktiviteter som görs i verksamheten och resultatkvalitet återger prestationerna och effekterna av verksamheten. Med hjälp av analysmodellen skapas ett mönster över vilka aspekter som tydligast framträder i lagarna och förarbeten samt vilket perspektiv som är mest påtagligt i respektive lag. Genom analysmodellen har en överblick över varje sektor kunnat ges.

    Undersökningen är en dokumentstudie och baseras på lagtexter med relaterade propositioner samt statliga utredningar. De utvalda lagarna återfinns i bilaga 1. I analysen av materialet har först kvantitativa sökningar gjort på kvalitet och relaterade begrepp såsom kvalitetssäkring, kvalitetsgranskning, kvalitetskontroll samt kvalitetsutvärdering för att få en bild av om kvalitet är ett återkommande begrepp eller inte. Därefter har en granskning och tolkning gjorts för att utreda ur vilka aspekter som kvalitet beskrivs, samt vilket perspektiv som väger tyngst i skrivningar i lagen och dess förarbeten.

    Varje sektor är resultatredovisad för sig i särskilda avsnitt. Resultaten visar att kvalitetsbegreppet inom hälso- och sjukvården är frekvent förekommande ur aspekterna struktur och resultat, medan resultatkvalitet överlämnats till den autonoma medicinska professionen att definiera. I utbildningssektorn tycks förhållandet vara det motsatta där resultatkvalitet i form av måluppfyllelse är det centrala och betonas starkt även kvalitet i termer av struktur och process förekommer. Även i denna sektor lyfter lagstiftaren fram autonomi och egenkontroll i avseende på utbildning och forskning när det gäller att definiera vad som är god kvalitet i vetenskapliga processer och resultat.

    Inom socialtjänsten pågår ett arbete som syftar till att ta fram kvalitetsindikatorer ur olika aspekter inspirerat av hälso- och sjukvården. Idag är begreppet kvalitet tydligast uttryckt i socialtjänstlagen när det gäller aspekterna struktur och process i ett personalperspektiv. Även inom polis och kriminalvård tycks kvalitetsbegreppet öka i betydelse även i lagtexterna, där struktur- och processaspekter framkommer i kriminalvårdens nya fängelse- och häkteslagstftningen. I polislagen lyser dock begreppet kvalitet med sin frånvaro, vilket i sig inte hindrar att krav ställs på kvalitet genom andra kanaler.

    Undersökningen avslutas med en diskussion utifrån de sektorsvisa resultaten om behov av ständigt återkommande omprövningar av hur begreppet ska användas i lagen och avvägningar om risken för cementering av verksamheter å ena sida och rättsäkerhet samt tydlighet å den andra.

  • 100933.
    Örnerheim, Mattias
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Mapping via Time-Geography to Elucidate Institutional, Economic and Political Change2012In: Proceedings of 15th Uddevalla Symposium,2012, Entrepreneurship and Innovation Networks / [ed] Iréne Bernhard, Bohus: Ale Tryckteam , 2012, p. 1-10Conference paper (Refereed)
    Abstract [en]

    Change has always been an issue for studies in politics and economics. However, there are few systematic treatments of institutions. This paper exemplifies how institutions (i.e., rules, norms and conventions) relate to the time-geography concepts of constraints, which affect different agents, policy-making, as well as economic performance.This paper seeks to advance the current discussion and sets some groundwork for further elaboration on economic and political change from an ontological perspective based in time-geography. It offers an initial exploration of the analysis of institutional change by a conceptualization of constraints in time-geography.The contribution of this study lies in the fact that insights from a time-geography approach have the ability to make the evolutionary perspective more coherent in empirically-related works when grading and ordering institutions of relevance concerning economic and political evolvement.

  • 100934.
    Örnerheim, Mattias
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, The Institute of Technology.
    Marknadsskapande, valfrihet och e-hälsa i sjukvården: Utkast till avhandlingsdesign (lic.)2010Conference paper (Other academic)
  • 100935.
    Örnerheim, Mattias
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Mellan kunskap och politik: Kvalitetssystem och offentlig kunskapsstyrning i hälso- och sjukvården2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim with this thesis is to describe the quality development in Swedish healthcare from an institutional perspective, analyse implications of the development concerning the relationship between the medical profession and the public administrative system and discuss consequences for political direction and welfare organization. The study is based on four case studies and one conceptual analysis.

    The main conclusion is that the medical quality systems have been imbedded in the political management alongside the development towards a public knowledge management. The analysis has more specifically uncovered that quality registries in healthcare have been influenced by political ideologies, management ideas and ideas of transparency. It is also clear that open comparisons were an ‘unintended consequence’ of the quality registry development that has enhanced the development towards a public knowledge management.

    The analysis also shows that public knowledge management challenges the ideal of democratic enlightened understanding. The development of public knowledge management in the healthcare sector raises the question of who is governing whom in Swedish healthcare.

    List of papers
    1. Explaining Quality Management in the Danish and Swedish Public Health Sectors: Unintended Learning and Deliberate Co-Optation
    Open this publication in new window or tab >>Explaining Quality Management in the Danish and Swedish Public Health Sectors: Unintended Learning and Deliberate Co-Optation
    2016 (English)In: International Journal of Public Administration, ISSN 0190-0692, E-ISSN 1532-4265, Vol. 39, no 12, p. 963-975Article in journal (Refereed) Published
    Abstract [en]

    This article examines the development of diverse quality systems in the otherwise quite similar Danish and Swedish public health sectors. After decades of numerous piecemeal medical and managerial quality development programs in both countries, a nationwide mandatory accreditation system was introduced in the Danish health services in 2009. Nationwide quality indicator projects are also found in Sweden, but there has been political attempt to introduce a compulsory system. This article seeks to explain this difference. It argues, first, that resistance from the medical professions blocked the introduction of compulsory, nationwide quality systems in both countries for decades. Second, the implementation of the Danish accreditation system was triggered by a combination of unintended policy learning produced by local reforms in two counties and of the Ministry of Health’s carefully orchestrated policy process that served to co-opt critical voices in the medical profession.

    Place, publisher, year, edition, pages
    Routledge, 2016
    Keywords
    Historical institutionalism; path dependency; policy learning; quality managment systems
    National Category
    Public Administration Studies
    Identifiers
    urn:nbn:se:liu:diva-128223 (URN)10.1080/01900692.2015.1064959 (DOI)2-s2.0-84958530409 (Scopus ID)
    Available from: 2016-05-23 Created: 2016-05-23 Last updated: 2017-11-30Bibliographically approved
    2. What frames Quality Registers in Swedish Health Care: an institutional approach
    Open this publication in new window or tab >>What frames Quality Registers in Swedish Health Care: an institutional approach
    2011 (English)In: Proceedings from 14th Uddevalla Symposium, 2011 Entrepreneurial Knowledge, Technology and Transformation of Regions / [ed] Iréne Bernhard, Linköping: Linköping University Electronic Press, 2011, p. 1-19Conference paper, Published paper (Other academic)
    Abstract [en]

    Quality issues strike the classical conflict in a democratic health-care deliverysystem of different interests among the politicians, the medical profession andpublic officials. This cannot be studied as a cut-off whiz. Quality registers havedeveloped over the past 40 years. Therefore, this paper puts the innovation ofquality registers in an institutional perspective. Two things are essential in thispaper. First, this paper reviews the emergence of quality registers in Swedish healthcare as an effect of institutional arrangements. Second, it analyses the interactionof diverse factors in different institutional settings and logics. The relevant data forthe study was collected from official/unofficial policy documents and key actorinterviews.The empirical findings show that three different waves of development can betraced in history that has highly affected the development of quality registers. Italso shows that medical quality is framed and determined by physicians in line withprofessional knowledge and by the primary institutional logic of quality in medicalcare. However, organisational quality in health care is framed by the logic ofpublic equity of access based on a third party payer and the logic of managerialcontrol. These two paths of quality developments are now federating in aninstitutional logic of transparency. The contribution of this paper is importantbecause it produces insights in different institutional logics, which frames the riseof the two quality paths and the problems they have to face in order to merge. It also enhances the existing knowledge that institutions matter.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2011
    Series
    Research Reports 2011:05 University West, ISSN 1653-7831 ; 2011:05
    Keywords
    health care, institutional change, quality, innovation
    National Category
    Public Administration Studies
    Identifiers
    urn:nbn:se:liu:diva-88746 (URN)978-91-977943-2-9 (ISBN)
    Conference
    14th Uddevalla Symposium, 2011 Entrepreneurial Knowledge, Technology and Transformation of Regions, June 16-18, Bergamo, Italy
    Available from: 2013-02-19 Created: 2013-02-18 Last updated: 2016-08-31Bibliographically approved
    3. Path Dependence on New Roads. Institutional Development of Quality Registers
    Open this publication in new window or tab >>Path Dependence on New Roads. Institutional Development of Quality Registers
    2014 (English)In: Offentlig Förvaltning. Scandinavian Journal of Public Administration, ISSN 2000-8058, E-ISSN 2001-3310, Vol. 18, no 2, p. 3-22Article in journal (Refereed) Published
    Abstract [en]

    When explaining social development and changes in public administration, institutional changeis a typical focus. Institutional analysis can combine the analyses of changes on the basis offormal legal and informal arrangements; it commonly shows that institutions lead to inertiawhere changes over time are concerned. Political aims are a guide to how organizations aredesigned and governed. When goals and earlier decisions clearly guide change, path dependenceis a fundamental concept when explaining change. However, this analysis shows how andwhen quality registers appeared as an answer to changes in institutional arrangements in Swedishpublic healthcare. Through three phases, cumulative processes have been visible and theprocesses have been followed by an improved and increased usage of quality registers andother quality systems. This analysis shows that institutional development can be pathdependentin relation to methods and means. Despite changing goals over time, quality registersas a policy tool have been path-dependent and stayed firm. Thus, it is important to see alsoorganisational methods as a development path that can be used to implement even new policyaims.

    Place, publisher, year, edition, pages
    Förlag Göteborgs Universitet, 2014
    Keywords
    Institutional change, quality registers, public governance, path dependence, time
    National Category
    Public Administration Studies
    Identifiers
    urn:nbn:se:liu:diva-114514 (URN)
    Available from: 2015-02-25 Created: 2015-02-25 Last updated: 2018-06-15Bibliographically approved
    4. Policymaking through healthcare registries in Sweden
    Open this publication in new window or tab >>Policymaking through healthcare registries in Sweden
    2018 (English)In: Health Promotion International, ISSN 0957-4824, E-ISSN 1460-2245, Vol. 33, no 2, p. 356-365Article in journal (Refereed) Published
    Abstract [en]

    Healthcare registries, otherwise known in Sweden as national quality registries (NQRs), have progressed from being a patient-focused system supporting medical results to become the basis of a health policy steering instrument called regional comparisons (RCs). This article seeks to explain RCs as an unintended consequence of the NQR development, by utilizing the concepts of policy entrepreneurs and streams of impact: the problem stream (problem perceived), the policy stream (what is valid), and the political stream (governmental objectives). The empirical contribution lies in insights on how the RCs have developed as an unintended consequence of entrepreneurial deliberate action in the process of creating NQRs. These findings are based on documents, interviews, and previous research in the social sciences. The article also argues for a critical understanding of public knowledge management (PKM) related to experiences in the development of NQRs regarding how to use knowledge in healthcare government. This article highlights how knowledge generated in quality systems based on registries could imply a stronger role for authorities in exerting control over the medical profession. It also discusses the potential use of research evidence on NQRs as a base for more efficient policymaking.

    Place, publisher, year, edition, pages
    Oxford University Press, 2018
    Keywords
    quality registries, stream coupling, policy entrepreneurs, public knowledge management
    National Category
    Political Science
    Identifiers
    urn:nbn:se:liu:diva-131037 (URN)10.1093/heapro/daw064 (DOI)000429490000018 ()27594141 (PubMedID)
    Available from: 2016-09-06 Created: 2016-09-06 Last updated: 2018-04-26Bibliographically approved
    5. Public quality – for whom and how?: Integrating public core values with quality management
    Open this publication in new window or tab >>Public quality – for whom and how?: Integrating public core values with quality management
    2017 (English)In: Total quality management and business excellence (Online), ISSN 1478-3363, E-ISSN 1478-3371, Vol. 28, no 3-4, p. 379-389Article in journal (Refereed) Published
    Abstract [en]

    Quality management (QM) plays an important role in public organisations’ efforts to create better access to, and effectiveness of, specific services. When transferring QM models from market-based firms to public services provided by public organisations, several basic contrasts and even contradictions must be addressed. Core values of the public sector differ from those of the private sector, but what are the consequences of this distinction? In this article we discuss the importance of four central arguments on public services: rights and access have to be considered; equality is an important facet of public services; coerciveness is a unique feature of public services; and legitimacy can be improved by high-quality services. These arguments have not been discussed explicitly in the context of QM. Adding these central aspects of public services to the QM field could generate more sustainable ways for developing quality and QM in public services in particular and the public sector in general.

    Place, publisher, year, edition, pages
    Routledge, 2017
    Keywords
    public sector; customer; citizen; quality management
    National Category
    Public Administration Studies
    Identifiers
    urn:nbn:se:liu:diva-128224 (URN)10.1080/14783363.2015.1087841 (DOI)000397039800010 ()2-s2.0-84945236799 (Scopus ID)
    Available from: 2016-05-23 Created: 2016-05-23 Last updated: 2018-06-15Bibliographically approved
  • 100936.
    Örnerheim, Mattias
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Policymaking through healthcare registries in Sweden2018In: Health Promotion International, ISSN 0957-4824, E-ISSN 1460-2245, Vol. 33, no 2, p. 356-365Article in journal (Refereed)
    Abstract [en]

    Healthcare registries, otherwise known in Sweden as national quality registries (NQRs), have progressed from being a patient-focused system supporting medical results to become the basis of a health policy steering instrument called regional comparisons (RCs). This article seeks to explain RCs as an unintended consequence of the NQR development, by utilizing the concepts of policy entrepreneurs and streams of impact: the problem stream (problem perceived), the policy stream (what is valid), and the political stream (governmental objectives). The empirical contribution lies in insights on how the RCs have developed as an unintended consequence of entrepreneurial deliberate action in the process of creating NQRs. These findings are based on documents, interviews, and previous research in the social sciences. The article also argues for a critical understanding of public knowledge management (PKM) related to experiences in the development of NQRs regarding how to use knowledge in healthcare government. This article highlights how knowledge generated in quality systems based on registries could imply a stronger role for authorities in exerting control over the medical profession. It also discusses the potential use of research evidence on NQRs as a base for more efficient policymaking.

  • 100937.
    Örnerheim, Mattias
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    What frames Quality Registers in Swedish Health Care: an institutional approach2011In: Proceedings from 14th Uddevalla Symposium, 2011 Entrepreneurial Knowledge, Technology and Transformation of Regions / [ed] Iréne Bernhard, Linköping: Linköping University Electronic Press, 2011, p. 1-19Conference paper (Other academic)
    Abstract [en]

    Quality issues strike the classical conflict in a democratic health-care deliverysystem of different interests among the politicians, the medical profession andpublic officials. This cannot be studied as a cut-off whiz. Quality registers havedeveloped over the past 40 years. Therefore, this paper puts the innovation ofquality registers in an institutional perspective. Two things are essential in thispaper. First, this paper reviews the emergence of quality registers in Swedish healthcare as an effect of institutional arrangements. Second, it analyses the interactionof diverse factors in different institutional settings and logics. The relevant data forthe study was collected from official/unofficial policy documents and key actorinterviews.The empirical findings show that three different waves of development can betraced in history that has highly affected the development of quality registers. Italso shows that medical quality is framed and determined by physicians in line withprofessional knowledge and by the primary institutional logic of quality in medicalcare. However, organisational quality in health care is framed by the logic ofpublic equity of access based on a third party payer and the logic of managerialcontrol. These two paths of quality developments are now federating in aninstitutional logic of transparency. The contribution of this paper is importantbecause it produces insights in different institutional logics, which frames the riseof the two quality paths and the problems they have to face in order to merge. It also enhances the existing knowledge that institutions matter.

  • 100938.
    Örnerheim, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Elg, Mattias
    Linköping University, Department of Management and Engineering, Logistics & Quality Management. Linköping University, Faculty of Science & Engineering.
    Implementering i vården: En kunskapsöversikt om beslutsnivåer och professionsperspektiv2018Report (Other academic)
    Abstract [sv]

    Hälso- och sjukvården liksom socialtjänsten är under ständig förändring – medicinska framsteg skapar nya möjligheter till behandling samtidigt som behoven av hälso- och sjukvård och socialtjänst ökar i takt med att allt fler lever längre med kroniska sjukdomar. Socialtjänsten kommer att behöva stödja fler med långvariga och komplexa behov, vilket band annat kommer att ställa krav på ändrade arbetssätt. En fortsatt utveckling i vården och omsorgen är viktigt för att i dag och i framtiden kunna tillhandahålla en god vård och omsorg som patienter och brukare känner förtroende för.Samtidigt finns tecken på att utvecklingen och lärandet inte sker i den omfattning som behövs. I olika analyser har Vårdanalys genom åren visat att lärandet mellan olika verksamheter och huvudmän är begränsat. Orsakerna bakom det är flera.Hösten 2017 initierade vi ett forskningsuppdrag med ambitionen att utifrån litteraturen identifiera övergripande utmaningar när det gäller implementering i hälso- och sjukvården och socialtjänsten. Vi gav professor Mattias Elg och postdoktor Mattias Örnerheim vid institutionen för ekonomisk och industriell utveckling (IEI), Linköpings universitet, uppdraget att presentera en kunskapsöversikt på detta tema.Deras översikt har varit ett värdefullt bidrag till Vårdanalys arbeten under 2017 och 2018 som på olika sätt analyserat utvecklingsarbete och deras förutsättningar att bidra till långsiktig utveckling. Det är vår förhoppning att den här promemorian kan tjäna som ett kunskapsunderlag i den fortsatta diskussionen om hur vi kan skapa bättre förutsättningar till lärande och utveckling i vården och omsorgen.Den här promemorian är författarnas redovisning av forskningsuppdraget i sin helhet och de står själva för innehållet.

  • 100939.
    Örnerheim, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Triantafilloub, Peter
    Department of Society and Globalisation, Roskilde University,Roskilde, Denmark.
    Explaining Quality Management in the Danish and Swedish Public Health Sectors: Unintended Learning and Deliberate Co-Optation2016In: International Journal of Public Administration, ISSN 0190-0692, E-ISSN 1532-4265, Vol. 39, no 12, p. 963-975Article in journal (Refereed)
    Abstract [en]

    This article examines the development of diverse quality systems in the otherwise quite similar Danish and Swedish public health sectors. After decades of numerous piecemeal medical and managerial quality development programs in both countries, a nationwide mandatory accreditation system was introduced in the Danish health services in 2009. Nationwide quality indicator projects are also found in Sweden, but there has been political attempt to introduce a compulsory system. This article seeks to explain this difference. It argues, first, that resistance from the medical professions blocked the introduction of compulsory, nationwide quality systems in both countries for decades. Second, the implementation of the Danish accreditation system was triggered by a combination of unintended policy learning produced by local reforms in two counties and of the Ministry of Health’s carefully orchestrated policy process that served to co-opt critical voices in the medical profession.

  • 100940.
    Örnerheim, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Wihlborg, Elin
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Path Dependence on New Roads. Institutional Development of Quality Registers2014In: Offentlig Förvaltning. Scandinavian Journal of Public Administration, ISSN 2000-8058, E-ISSN 2001-3310, Vol. 18, no 2, p. 3-22Article in journal (Refereed)
    Abstract [en]

    When explaining social development and changes in public administration, institutional changeis a typical focus. Institutional analysis can combine the analyses of changes on the basis offormal legal and informal arrangements; it commonly shows that institutions lead to inertiawhere changes over time are concerned. Political aims are a guide to how organizations aredesigned and governed. When goals and earlier decisions clearly guide change, path dependenceis a fundamental concept when explaining change. However, this analysis shows how andwhen quality registers appeared as an answer to changes in institutional arrangements in Swedishpublic healthcare. Through three phases, cumulative processes have been visible and theprocesses have been followed by an improved and increased usage of quality registers andother quality systems. This analysis shows that institutional development can be pathdependentin relation to methods and means. Despite changing goals over time, quality registersas a policy tool have been path-dependent and stayed firm. Thus, it is important to see alsoorganisational methods as a development path that can be used to implement even new policyaims.

  • 100941.
    Örtegren, Hanna
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Work and Working Life.
    Wahlberg, Ellinor
    Linköping University, Department of Behavioural Sciences and Learning, Work and Working Life. Linköping University, Department of Behavioural Sciences and Learning, Education and Sociology.
    Att arbeta i ett aktivitetsbaserat kontor - givande eller påfrestande?: En kvalitativ studie om hur anställda upplever det aktivitetsbaserade kontoret och dess implementering.2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bakgrund och syfte:Arbetet i ett aktivitetsbaserat kontor innebär både utmaningar och möjligheter. Syftet med studien är därför att undersöka vilka dessa är genom att studera hur ett företag som implementerat konceptet genomförde införandet, vilka effekter konceptet medfört samt huruvida arbetssättet tillgodoser den enskilde medarbetarens behov.

    Metod:Studien grundas i en kvalitativ metod och semistrukturerade intervjuer genomförda på ett fastighetsbolag som implementerat konceptet. Empirin har sedan analyserats och diskuterats i relation till forskning och teori inom aktuellt området.

    Resultat:Resultatet visar att implementeringsprocessen har stor inverkan på hur konceptet upplevs och används efter införandet samt att både kunskaps- och informationsflödet påverkats positivt. Resultatet visar på utmaningar gällande koncentration och avskildhet, vilket lett till vissa justeringar.

    Slutsatser:Viktiga slutsatser är betydelsen av att i ett tidigt skede av processen involvera medarbetarna i den förändring som arbetssättet innebär samt att konceptet kan ha en positiv inverkan på kunskaps- och informationsspridningen samt sammanhållningen.

  • 100942.
    Örtegren, Jonas
    et al.
    Department of Polymer Technology, Royal Institute of Technology, Stockholm, Sweden.
    Andersson, Gunnar
    Physics Department, Chalmers University of Technology, Göteborg, Sweden.
    Busson, Philippe
    Department of Polymer Technology, Royal Institute of Technology, Stockholm, Sweden.
    Hult, Anders
    Department of Polymer Technology, Royal Institute of Technology, Stockholm, Sweden.
    Gedde, Ulf W.
    Department of Polymer Technology, Royal Institute of Technology, Stockholm, Sweden.
    Eriksson, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Health Sciences.
    Lindgren, Mikael
    National Defence Research Establishment, Linköping, Sweden.
    Improved thermal stability of pyroelectric polymers by crosslinking of ferroelectric liquid crystals2001In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 105, no 42, p. 10223-10227Article in journal (Refereed)
    Abstract [en]

    Monofunctional ferroelectric liquid crystalline monomers and a blend of monofunctional/bifunctional ferroelectric liquid crystalline monomers were photopolymerized, yielding a side-chain liquid crystalline polymer and a cross-linked polymer, respectively. The cross-linked polymer exhibited higher thermal stability than the side-chain liquid crystalline polymer and was pyroelectric up to 170 °C, whereas the side-chain liquid crystalline polymer lost most of its pyroelectricity at 38 °C. It is shown by electrooptic and birefringence measurements that cross-linking in the unwound SmC* phase prevented the reoccurrence of the helical superstructure.

  • 100943.
    Örtegren, Jonas
    et al.
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Busson, Philippe
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Gedde, Ulf W.
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Hult, Anders
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Eriksson, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Andersson, Gunnas
    Physics Department, Chalmers University of Technology, Göteborg, Sweden.
    Cone motion viscosity and optical second harmonic generation of ferroelectric liquid crystalline dendrimers2001In: Liquid crystals (Print), ISSN 0267-8292, E-ISSN 1366-5855, Vol. 28, no 6, p. 861-868Article in journal (Refereed)
    Abstract [en]

    We report second harmonic generation in a ferroelectric liquid crystalline trimer and ferroelectric liquid crystalline dendrimers of first, second and third generation. Thin cells were filled with the compounds by capillary forces at elevated temperature, and cooled from the surface stabilized ferroelectric state to below the glass transition temperature, while kept in an electric field. The cone motion viscosity and the threshold electric field for unwinding of the helix axis of the chiral tilted smectic mesophases were studied separately at elevated temperature, and these data were used to optimize the preparation of the films. The measured response time was between 0.3 and 3ms, which corresponds to a cone motion viscosity between 0.5 and 50 Pa s. Second harmonic generation was studied both at elevated temperature with an electric field and at room temperature with and without electric field. The first generation dendrimer exhibited a strong increase in the second order non-linear optical response with time at room temperature. The d 23-coefficient of this dendrimer was approximately four times larger than for the other macromolecules and was 0.045 pm V-1. The relatively large d-coefficient of the first generation dendrimer is ascribed to crystallization, which improved the orientation of the molecular dipoles.

  • 100944.
    Örtegren, Jonas
    et al.
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Busson, Philippe
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Gedde, Ulf W.
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Hult, Anders
    Department of Polymer Technology, Royal Institute of Technology, Sweden.
    Eriksson, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Arntzén, Per-Otto
    National Defence Research Establishment, Linköping, Sweden.
    Hermann, David S.
    Physics Department, Chalmers University of Technology,Göteborg, Sweden.
    Rudquist, Per
    Physics Department, Chalmers University of Technology,Göteborg, Sweden.
    Lagerwall, Sven T.
    Physics Department, Chalmers University of Technology,Göteborg, Sweden.
    Time-dependent nonlinear optical properties of pyroelectric liquid crystalline polymers1999In: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 148, p. 179-195Article in journal (Refereed)
    Abstract [en]

    Highly oriented pyroelectric liquid-crystalline polymers were prepared by photopolymerization under the influence of a static electric field from binary mixtures of two acrylate monomers exhibiting chiral smectic C mesomorphism. Both monomers contained nitro groups to yield second order nonlinear optical properties (second harmonic generation) and one of the monomers had two functional groups to yield a crosslinked polymer. The room temperature second order nonlinear susceptibility of the polymers showed during the first two hours a 10 % decrease after which it remained constant during the next 48 days. At elevated temperatures there was a significant difference in the nonlinear optical properties over time between crosslinked and uncrosslinked polymers. The uncrosslinked polymer showed a pronounced loss of second order nonlinear optical activity with time at ≥38°C. The crosslinked polymer showed a much smaller and basically a temperature independent decrease rate in the second order nonlinear optical properties at all the ageing temperatures (23-130°C). Both the loss in mesogen order parameter, very evident for the uncrosslinked polymer, and conformational changes occurring within the mesogens (β mechanism), may account for the observations made.

  • 100945.
    Örtegren Kugelberg, Unn
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Central adipocyte functions in specialized caveolae2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Obesity and overweight is an increasing health problem in the world. Besides reducing quality of life obesity is a great risk factor for development of diseases such as type 2 diabetes, cardiovascular disease, and stroke. The adipose tissue is a flexible organ that grows in size if the body is provided with excess energy. Adipocytes store the excess energy in the form of triacylglycerol. The incorporation of fat is stimulated by insulin, while catecholamines promote hydrolysis of triacylglycerol. In the membrane of adipocytes there are cave-like invaginations, caveolae, where proteins involved in insulin signalling, such as the insulin receptor are located. The focus of this thesis is on the function, and thereby the importance, of adipocytes and caveolae in metabolism.

    The lipid content of the plasma membrane and caveolae was analyzed and compared to lipid phases determined in model membranes. The amount of different membrane lipids indicated heterogeneity of the caveolae, since there were not enough of some specific molecules to be present in every caveola. Using density gradient ultra centrifugation three different subclasses of caveolae were identified. These subclasses were named according to their relative densities: very high density caveolae, high density caveolae and low density caveolae. There were clear differences between the classes with regard to the distribution of specific proteins in them. In low density caveolae proteins linked to cholesterol metabolism, scavenger receptor class B type I and CD36, were abundant. Proteins involved in fatty acid metabolism, fatty acid transporter protein 1 and 4, acyl CoA-syntethase, perilipin and hormone sensitive lipase, were localized to high density caveolae. Cholesteryl ester uptake from HDL particles and hydrolysis to cholesterol was found in low density caveolae and the uptake of fatty acids was restricted to high density caveolae. Remarkably, the fatty acids were not only taken up via high density caveolae, but also incorporated into triacylglycerol, diacylglycerol, and phosphatidylcholine. This indicates that the whole machinery for lipid synthesis is located in these caveolae.

    In addition to being an energy store the adipose tissue is also an endocrine organ. Several of the secreted proteins affect the metabolism of the body, for instance adiponectin that affects insulin sensitivity. Here adiponectin was located at the plasma membrane to the caveolae, both by biochemical isolation of caveolae and by electron microscopy. Together with earlier findings this indicates that caveolae may be involved in the secretion of adiponectin.

    In conclusion, caveolae are involved in central processes such as glucose metabolism and signalling. Herein it is shown that caveolae is involved in the metabolism of fatty acids and cholesterol and may also be involved in the secretion of the metabolic hormone adiponectin. The findings in this thesis together with previous research establish caveolae as metabolic platforms.

    List of papers
    1. Lipids and glycosphingolipids in caveolae and surrounding plasma membrane of primary rat adipocytes
    Open this publication in new window or tab >>Lipids and glycosphingolipids in caveolae and surrounding plasma membrane of primary rat adipocytes
    Show others...
    2004 (English)In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 271, no 10, p. 2028-2036Article in journal (Refereed) Published
    Abstract [en]

    We have made a comprehensive and quantitative analysis of the lipid composition of caveolae from primary rat fat cells and compared the composition of plasma membrane inside and outside caveolae. We isolated caveolae from purified plasma membranes using ultrasonication in carbonate buffer to disrupt the membrane, or extraction with nonionic detergent, followed by density gradient ultracentrifugation. The carbonate-isolated caveolae fraction was further immunopurified using caveolin antibodies. Carbonate-isolated caveolae were enriched in cholesterol and sphingomyelin, and the concentration was three- and twofold higher, respectively, in caveolae compared to the surrounding plasma membrane. The concentration of glycerophospholipids was similar suggesting that glycerophospholipids constitute a constant core throughout the plasma membrane. The composition of detergent-insoluble fractions of the plasma membrane was very variable between preparations, but strongly enriched in sphingomyelin and depleted of glycerophospholipids compared to carbonate-isolated caveolae; indicating that detergent extraction is not a suitable technique for caveolae preparation. An average adipocyte caveola contained about 22 × 103 molecules of cholesterol, 7.5 × 103 of sphingomyelin and 23 × 103 of glycerophospholipid. The glycosphingolipid GD3 was highly enriched in caveolae, whereas GM3, GM1 and GD1a were present inside as well as outside the caveolae membrane. GD1b, GT1b, GM2, GQ1b, sulfatide and lactosylceramide sulfate were not detected in caveolae.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-22409 (URN)10.1111/j.1432-1033.2004.04117.x (DOI)1621 (Local ID)1621 (Archive number)1621 (OAI)
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
    2. Triacylglycerol is synthesized in a specific subclass of caveolae in primary adipocytes
    Open this publication in new window or tab >>Triacylglycerol is synthesized in a specific subclass of caveolae in primary adipocytes
    Show others...
    2005 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 280, no 1, p. 5-8Article in journal (Refereed) Published
    Abstract [en]

    A principal metabolic function of adipocytes is to synthesize triacylglycerol (TG) from exogenous fatty acids. The level of fatty acids has to be tightly controlled in the adipocyte, as they can act as detergents that rapidly dissolve the plasma membrane, causing cell lysis if allowed to accumulate. Fatty acids therefore have to be efficiently converted to TG and stored in the central lipid droplet. We report that in intact primary adipocytes exogenous oleic acid was taken up and directly converted to TG in the plasma membrane, in a novel subclass of caveolae that specifically contains the protein perilipin. Isolated caveolae catalyzed de novo TG synthesis from oleic acid and glycerol 3-phosphate. Electron microscopy revealed the presence of caveolin and perilipin in caveolae and in lipid-laden bulbs in the plasma membrane, and fluorescence microscopy demonstrated colocalization of fatty acids/TG with caveolin and perilipin at the plasma membrane. A second caveolae fraction was isolated, which lacked perilipin and the triacylglycerol synthesizing enzymes. Both caveolae fractions contained caveolin-1 and the insulin receptor. The findings demonstrate that specific subclasses of caveolae carry out specific functions in cell metabolism. In particular, triacylglycerol is synthesized at the site of fatty acid entry in one of these caveolae classes.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-20650 (URN)10.1074/jbc.C400429200 (DOI)15537657 (PubMedID)
    Available from: 2009-09-16 Created: 2009-09-16 Last updated: 2017-12-13Bibliographically approved
    3. Separation and characterization of caveolae subclasses in the plasma membrane of primary adipocytes: segregation of specific proteins and functions
    Open this publication in new window or tab >>Separation and characterization of caveolae subclasses in the plasma membrane of primary adipocytes: segregation of specific proteins and functions
    Show others...
    2006 (English)In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 273, no 14, p. 3381-3392Article in journal (Refereed) Published
    Abstract [en]

    Caveolae are nearly ubiquitous plasma membrane domains that in adipocytes vary in size between 25 and 150 nm. They constitute sites of entry into the cell as well as platforms for cell signalling. We have previously reported that plasma membrane-associated caveolae that lack cell surface access can be identified by electron microscopy. We now report the identification, after density gradient ultracentrifugation, of a subclass of very high-density apparently closed caveolae that were not labelled by cell surface protein labelling of intact cells. These caveolae contained caveolin-1 and caveolin-2. Another class of high-density caveolae contained caveolin-1, caveolin-2 and specifically fatty acid transport protein-1, fatty acid transport protein-4, fatty acyl-CoA synthetase, hormone-sensitive lipase, perilipin, and insulin-regulated glucose transporter-4. This class of caveolae was specialized in fatty acid uptake and conversion to triacylglycerol. A third class of low-density caveolae contained the insulin receptor, class B scavenger receptor-1, and insulin-regulated glucose transporter-4. Small amounts of these proteins were also detected in the high-density caveolae. In response to insulin, the insulin receptor autophosphorylation and the amount of insulin-regulated glucose transporter-4 increased in these caveolae. The molar ratio of cholesterol to phospholipid in the three caveolae classes varied considerably, from 0.4 in very high-density caveolae to 0.9 in low-density caveolae. There was no correlation between the caveolar contents of caveolin and cholesterol. The low-density caveolae, with the highest cholesterol concentration, were particularly enriched with the cholesterol-rich lipoprotein receptor class B scavenger receptor-1, which mediated cholesteryl ester uptake from high-density lipoprotein and generation of free cholesterol in these caveolae, suggesting a specific role in cholesterol uptake/metabolism. These findings demonstrate a segregation of functions in caveolae subclasses.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-35681 (URN)10.1111/j.1742-4658.2006.05345.x (DOI)28128 (Local ID)28128 (Archive number)28128 (OAI)
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13Bibliographically approved
    4. Localization of adiponectin at the plasma membrane in caveolae of human adipocytes
    Open this publication in new window or tab >>Localization of adiponectin at the plasma membrane in caveolae of human adipocytes
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The hormone adiponectin is exclusively secreted by adipocytes and it regulates whole body energy homeostasis primarily by affecting liver and muscles. The circulating level of adiponectin inversely correlates with insulin resistance and type 2 diabetes. Little is known about the secretion of adiponectin by the adipocyte, but in caveolin-1 knockout mice the amount of secreted adiponectin is severely reduced. Here we show that in human adipocytes adiponectin was associated with the plasma membrane and to a specific class of high-density-caveolae. Substantial amounts of adiponectin were also found in the microsomal and cytosolic fractions of adipocytes, while very little was associated with mitochondria, nuclei, or the fat. Adiponectin in isolated caveolae was readily degraded by added trypsin, demonstrating that adiponectin was largely bound to the cytosolic face of the caveolae membrane. The findings indicate that caveolae may have a critical role in the secretion of adiponectin by human adipocytes.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84835 (URN)
    Available from: 2012-10-24 Created: 2012-10-24 Last updated: 2012-10-24Bibliographically approved
  • 100946.
    Örtegren Kugelberg, Unn
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Yin, Lan
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Öst, Anita
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Karlsson, Helen
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Nyström, Fredrik
    Linköping University, Department of Medicine and Care, Internal Medicine. Linköping University, Faculty of Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Separation and characterization of caveolae subclasses in the plasma membrane of primary adipocytes: segregation of specific proteins and functions2006In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 273, no 14, p. 3381-3392Article in journal (Refereed)
    Abstract [en]

    Caveolae are nearly ubiquitous plasma membrane domains that in adipocytes vary in size between 25 and 150 nm. They constitute sites of entry into the cell as well as platforms for cell signalling. We have previously reported that plasma membrane-associated caveolae that lack cell surface access can be identified by electron microscopy. We now report the identification, after density gradient ultracentrifugation, of a subclass of very high-density apparently closed caveolae that were not labelled by cell surface protein labelling of intact cells. These caveolae contained caveolin-1 and caveolin-2. Another class of high-density caveolae contained caveolin-1, caveolin-2 and specifically fatty acid transport protein-1, fatty acid transport protein-4, fatty acyl-CoA synthetase, hormone-sensitive lipase, perilipin, and insulin-regulated glucose transporter-4. This class of caveolae was specialized in fatty acid uptake and conversion to triacylglycerol. A third class of low-density caveolae contained the insulin receptor, class B scavenger receptor-1, and insulin-regulated glucose transporter-4. Small amounts of these proteins were also detected in the high-density caveolae. In response to insulin, the insulin receptor autophosphorylation and the amount of insulin-regulated glucose transporter-4 increased in these caveolae. The molar ratio of cholesterol to phospholipid in the three caveolae classes varied considerably, from 0.4 in very high-density caveolae to 0.9 in low-density caveolae. There was no correlation between the caveolar contents of caveolin and cholesterol. The low-density caveolae, with the highest cholesterol concentration, were particularly enriched with the cholesterol-rich lipoprotein receptor class B scavenger receptor-1, which mediated cholesteryl ester uptake from high-density lipoprotein and generation of free cholesterol in these caveolae, suggesting a specific role in cholesterol uptake/metabolism. These findings demonstrate a segregation of functions in caveolae subclasses.

  • 100947.
    Örtegren, Unn
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Aboulaich, Nabila
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Öst, Anita
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    A new role for caveolae as metabolic platforms2007In: Trends in endocrinology and metabolism, ISSN 1043-2760, E-ISSN 1879-3061, Vol. 18, no 9, p. 344-349Article in journal (Refereed)
    Abstract [en]

    The plasma membrane of cells functions as a barrier to the environment. Caveolae are minute invaginations of the membrane that selectively carry out the exchange of information and materials with the environment, by functioning as organizers of signal transduction and through endocytosis. Recent findings of uptake of different metabolites and of lipid metabolism occurring in caveolae, point to a new general function of caveolae. As gateways for the uptake of nutrients across the plasma membrane, and as platforms for the metabolic conversion of nutrients, especially in adipocytes, caveolae are now emerging as active centers for many aspects of intermediary metabolism, with implications for our understanding of obesity, diabetes and other metabolic disorders.

  • 100948.
    Örtegren, Unn
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Karlsson, Margareta
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Blazic, Natascha
    Department of Clinical Neuroscience, Sahlgrenska University Hospital/Mölndal, Göteborg University, Mölndal, Sweden.
    Blomqvist, Maria
    Department of Clinical Neuroscience, Sahlgrenska University Hospital/Mölndal, Göteborg University, Mölndal, Sweden.
    Nyström, Fredrik
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Gustavsson, Johanna
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Fredman, Pam
    Department of Clinical Neuroscience, Sahlgrenska University Hospital/Mölndal, Göteborg University, Mölndal, Sweden.
    Strålfors, Peter
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Lipids and glycosphingolipids in caveolae and surrounding plasma membrane of primary rat adipocytes2004In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 271, no 10, p. 2028-2036Article in journal (Refereed)
    Abstract [en]

    We have made a comprehensive and quantitative analysis of the lipid composition of caveolae from primary rat fat cells and compared the composition of plasma membrane inside and outside caveolae. We isolated caveolae from purified plasma membranes using ultrasonication in carbonate buffer to disrupt the membrane, or extraction with nonionic detergent, followed by density gradient ultracentrifugation. The carbonate-isolated caveolae fraction was further immunopurified using caveolin antibodies. Carbonate-isolated caveolae were enriched in cholesterol and sphingomyelin, and the concentration was three- and twofold higher, respectively, in caveolae compared to the surrounding plasma membrane. The concentration of glycerophospholipids was similar suggesting that glycerophospholipids constitute a constant core throughout the plasma membrane. The composition of detergent-insoluble fractions of the plasma membrane was very variable between preparations, but strongly enriched in sphingomyelin and depleted of glycerophospholipids compared to carbonate-isolated caveolae; indicating that detergent extraction is not a suitable technique for caveolae preparation. An average adipocyte caveola contained about 22 × 103 molecules of cholesterol, 7.5 × 103 of sphingomyelin and 23 × 103 of glycerophospholipid. The glycosphingolipid GD3 was highly enriched in caveolae, whereas GM3, GM1 and GD1a were present inside as well as outside the caveolae membrane. GD1b, GT1b, GM2, GQ1b, sulfatide and lactosylceramide sulfate were not detected in caveolae.

  • 100949.
    Örtegren, Unn
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Scherer, Philipp
    Albert Einstein College of Medicine, New York, NY, USA.
    Strålfors, Peter
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Localization of adiponectin at the plasma membrane in caveolae of human adipocytesManuscript (preprint) (Other academic)
    Abstract [en]

    The hormone adiponectin is exclusively secreted by adipocytes and it regulates whole body energy homeostasis primarily by affecting liver and muscles. The circulating level of adiponectin inversely correlates with insulin resistance and type 2 diabetes. Little is known about the secretion of adiponectin by the adipocyte, but in caveolin-1 knockout mice the amount of secreted adiponectin is severely reduced. Here we show that in human adipocytes adiponectin was associated with the plasma membrane and to a specific class of high-density-caveolae. Substantial amounts of adiponectin were also found in the microsomal and cytosolic fractions of adipocytes, while very little was associated with mitochondria, nuclei, or the fat. Adiponectin in isolated caveolae was readily degraded by added trypsin, demonstrating that adiponectin was largely bound to the cytosolic face of the caveolae membrane. The findings indicate that caveolae may have a critical role in the secretion of adiponectin by human adipocytes.

  • 100950.
    Örtenberg, Alexander
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Parallelization of DIRA and CTmod Using OpenMP and OpenCL2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Parallelization is the answer to the ever-growing demands of computing power by taking advantage of multi-core processor technology and modern many-core graphics compute units. Multi-core CPUs and many-core GPUs have the potential to substantially reduce the execution time of a program but it is often a challenging task to ensure that all available hardware is utilized. OpenMP and OpenCL are two parallel programming frameworks that have been developed to allow programmers to focus on high-level parallelism rather than dealing with low-level thread creation and management. This thesis applies these frameworks to the area of computed tomography by parallelizing the image reconstruction algorithm DIRA and the photon transport simulation toolkit CTmod. DIRA is a model-based iterative reconstruction algorithm in dual-energy computed tomography, which has the potential to improve the accuracy of dose planning in radiation therapy. CTmod is a toolkit for simulating primary and scatter projections in computed tomography to optimize scanner design and image reconstruction algorithms. The results presented in this thesis show that parallelization combined with computational optimization substantially decreased execution times of these codes. For DIRA the execution time was reduced from two minutes to just eight seconds when using four iterations and a 16-core CPU so a speedup of 15 was achieved. CTmod produced similar results with a speedup of 14 when using a 16-core CPU. The results also showed that for these particular problems GPU computing was not the best solution.

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