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  • 101951.
    Åström Aneq, Meriam
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Linköping University, Faculty of Medicine and Health Sciences.
    Arytmogen högerkammarkardiomyopati2016In: Idrott och hjärtat / [ed] Mats Börjesson, Mikael Dellborg, Studentlitteratur, 2016, Vol. 1, p. 141-150Chapter in book (Other academic)
  • 101952.
    Åström Aneq, Meriam
    et al.
    Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Lindström, Lena
    Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences.
    Nylander, Eva
    Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Long-term follow-up in arrhythmogenic right ventricular cardiomyopathy using Tissue Doppler Imaging2008In: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 42, no 6, p. 368-374Article in journal (Refereed)
    Abstract [en]

    Aim: To study patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and describe different echocardiographic parameters and their change over time during almost 10 years follow-up period.

    Methods: Fifteen patients (9 male, 6 female), aged 22-58 years (mean 40) with a diagnosis of ARVC, were followed up for a period of 6-10 years (mean 8.7). Twelve-lead and a signal- averaged ECG was recorded. Tricuspid and mitral annular motion and tissue Doppler imaging were registered by echocardiography. Wall motion score index (WMSI) was calculated for the left and right ventricles.

    Results: We registered significant reduction in systolic tissue velocity on right ventricle free wall between the first and last investigations: 7-17cm/s (mean 11.8) to 4-15 (mean 9.1), p=0.005. WMSI increased by at least 0.2 in 10/14 patients for the right and in 8/15 patients for the left ventricle. A decrease in velocity time integral for the left ventricular outflow was observed (16-30 to 13-21, p=0.009).

    Conclusion: ARVC is a progressive disease with individual variation. Left ventricular involvement may occur early in the disease. Tissue Doppler imaging is a useful tool to follow-up right ventricular abnormalities.

  • 101953.
    Åström Aneq, Meriam
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Maret, Eva
    Karolinska University Hospital and Karolinska Institutet, Stockholm, Sweden.
    Brudin, Lars
    Department of Clinical Physiology, Kalmar County Hospital, Kalmar, Sweden.
    Svensson, Anneli
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Cardiology in Linköping.
    Engvall, Jan
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Right ventricular systolic function and mechanical dispersion identify patients with arrhythmogenic right ventricular cardiomyopathy.2018In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 38, no 5, p. 779-787Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To assess right ventricular (RV) regional and global systolic function using feature tracking (FT) in patients with a definite diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) and to investigate if changes in strain amplitude and mechanical dispersion indicate a propensity for arrhythmia.

    MATERIALS AND METHODS: Twenty-seven patients fulfilling Task Force Criteria for ARVC and 24 healthy volunteers underwent MR at 1·5 Tesla. Steady-state free precession cine of long-axis slices and a short-axis stack of the RV was acquired. Segmental longitudinal systolic strain amplitude and time-to-peak (TTP) strain were measured in the four- and two-chamber views of the RV.

    RESULTS: Compared to controls, patients with ARVC had lower RV ejection fraction (RVEF), (53% vs 57%, P = 0·012) and lower longitudinal strain amplitude in the RV free wall (-20·6 vs -26·3%, P = 0·014) and in the basal part of the RV (-22·8 vs -31·7%, P<0·001). Mechanical dispersion, defined as the standard deviation (SD) of TTP of RV segments, was larger in patients with ARVC (48 ms [21-74] vs 35 ms [13-66 ms], P = 0·02). Patients with ventricular tachycardia (VT) or non-sustained VT had lower RVEF (46% vs 55%, P = 0·008), but did not have significantly lower RV strain amplitude (-19·5% vs 21·0%, P = 0·073) and no signs of mechanical dispersion (49 ms vs 48 ms, P = 0·861) compared to patients without arrhythmia.

    CONCLUSION: ARVC patients had lower longitudinal absolute strain amplitude in basal RV segments and increased mechanical dispersion compared to healthy volunteers, but the presence of mechanical dispersion was not predictive of ventricular arrhythmia.

  • 101954.
    Åström, Anne N.
    et al.
    University of Bergen, Norway.
    Ekback, Gunnar
    Örebro County Council, Sweden; Örebro University, Sweden.
    Ordell, Sven
    Region Östergötland, Public Dental Health Care.
    Lie, Stein A.
    University of Bergen, Norway.
    Gulcan, Ferda
    University of Bergen, Norway.
    Dental hygienist attendance and its covariates in an ageing Swedish cohort2017In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 125, no 6, p. 487-494Article in journal (Refereed)
    Abstract [en]

    Delegation of tasks between professional groups is important to make health-care services accessible and effective for ageing people. Focussing on a Swedish 1942 birth cohort and guided by Andersens Behavioral Model, this study assessed dental hygienist attendance from age 50 to age 70 and identified covariates at the population-averaged and person-specific levels. In 1992, a census of 50-yr-old subjects was invited to participate in a questionnaire survey. Of the 6,346 respondents, 3,585 completed follow-ups in 1997, 2002, 2007, and 2012. Multiple logistic regression analysis was conducted using a marginal model and a random intercept model. Cochrans Q test revealed that significantly more respondents confirmed dental hygienist attendance in 2012 than in 1992 (57.2% in 2012 vs. 26.0% in 1992). Population-averaged ORs for dental hygienist attendance across time were 3.5 at age 70 yr compared with age 50 yr (baseline); 2.0 if being a regular rather than an irregular dental attendee; and 0.7 if being of non-native origin compared with native origin. The corresponding person-specific ORs were 8.9, 3.2, and 0.5. Consistent with Andersens Behavioral Model, predisposing, enabling, and need-related factors were associated with dental hygienist attendance at population-averaged and person-specific levels. This has implications for promoting dental hygienist attendance among ageing people.

  • 101955.
    Åström, Dick
    et al.
    Linköping University, Department of Social and Welfare Studies, Society, Diversity, Identity .
    Björkoholm, Jonas
    Linköping University, Department of Social and Welfare Studies, Society, Diversity, Identity .
    Planer för integration: En studie om idrottens betydelse för upplevelsen av integration bland ungdomar i ett etniskt definierat fotbollslag2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att belysa talet om idrottens betydelse för upplevelsen av integration bland ungdomar i 2000-talets Sverige. Studien bygger på tre fokusgruppsintervjuer med ungdomar som är 15 år och spelar fotboll i Assyriska FF, hemmahörande i Södertälje. Centralt har varit att belysa hur pojkarna beskriver sig själva i ljuset av att de ingår i ett etniskt definierat fotbollslag, och vilken roll de tillskriver tillhörigheten till ett sådant lag när det gäller upplevelsen av delaktighet i det svenska samhället. Vår studie knyter teoretiskt an till identitet, etnicitet och integration.

    Studien visar att en treenighet bestående av Familjen, Föreningen och Församlingen är centrala när det gäller skapandet av dessa ungdomars normer och värderingar. Vi har sett att denna treenighet också spelar en stor roll för ungdomarnas identitetsskapande, både vad gäller synen på sig själva som individer och för hur de ser på assyrier som etnisk grupp. Det har utöver detta framkommit att denna treenighet påverkar hur ungdomarna tror att assyrier betraktas av omvärlden och vilket ansvar de själva har, som grupp och individ, för att bilden av deras etniska grupp ska bli så positiv som möjligt. Vi har också förstått att dessa ungdomar menar att denna bild är avgörande för deras möjligheter till integration och delaktighet i samhället. Laget och föreningen tillskrivs en stor roll när det gäller att föra ut en positiv bild av assyrier i det omgivande samhället. Ungdomarna menar att det är här de fostras och formas till ansvarstagande individer som visar respekt för andra människor. Det är också i laget de kan växa och utvecklas genom att ’spegla’ sig i varandra. Dessa ungdomar ser denna möjlighet som avgörande inför framtiden, oavsett om de blir fotbollsproffs eller får nöja sig med ett vanligt jobb. De menar att de genom lagets fostran får en social kompetens som gör det möjligt att bli delaktig och få en berättigad plats i det svenska samhället, vilket är eftersträvansvärt då de känner sig både som assyrier och svenskar, dubbla integrerade identiteter. Laget har därmed en viktig roll i ungdomarnas identitetsskapande och för hur de ser på den etniska gruppen assyrier och dess möjligheter att integreras i det svenska samhället.

  • 101956.
    Åström, Eva
    Linköping University, The Tema Institute, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Att lära, att göra, att klara: Förmedling av datortekniska hjälpmedel till barn med synnedsättning. Från förskrivning till vardaglig användning i skola och hem2009Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The ability to use information and communication technology is regarded today as acondition for participation in society. Closely associated with this are measurestaken to reduce the digital divide in society. Computer technology is accepted asmaking it possible for people with disabilities to manage most things on their ownthat previously required some help of others. However, access to technology doesnot necessarily equal usability. This thesis explores and analyses the mediationprocess that occurs when children with visual impairment, access assistive computertechnologies, and how these, by the help of support persons, are used in home and atschool. Eight children (between seven and eighteen years of age) were included inthe study, as well as their parents, support persons in school and professionals fromthe Low Vision Clinics. Research data have been collected through interviews,conversations, observations and activity oriented diaries. The mediation processinvolves a number of persons and organisations and is both organisationally complexand extended in time and space. Different rationalities are set against eachother, when professionally active persons from the Low Vision Clinics and schools,together with parents make it possible for the children to use the assistive devices.From the standpoint of the computer as an aid, three projects are discussed whosegoals are important for the child to achieve to be able to, in the short and long run,live life to the full. These projects are ‘learning’, ‘becoming socially involved’ and‘becoming independent’. The projects can often be in conflict with each other; forexample the children’s desire to practice on the computer against their wanting toplay with their friends at the same time. With a time-geographic approach,situations in which conflicts and trade-offs arise, as well as the coordination effortsmade by those involved, are analysed. The school constitutes an area in which theoverreaching societal ambition of a life on equal terms is realised. This studydiscusses how compensation for the individual as well as structural change foraccessibility manifests itself in organisation, structures and supportive efforts.

  • 101957.
    Åström, Eva
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Stal, Per
    Karolinska University Hospital, Sweden.
    Zenlander, Robin
    Karolinska University Hospital, Sweden.
    Edenvik, Pia
    Karolinska University Hospital, Sweden.
    Alexandersson, Catharina
    Kalmar County Hospital, Sweden.
    Haglund, Mats
    Kalmar County Hospital, Sweden.
    Ryden, Ingvar
    Kalmar County Hospital, Sweden.
    Påhlsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Reverse lectin ELISA for detecting fucosylated forms of alpha 1-acid glycoprotein associated with hepatocellular carcinoma2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 3, article id e0173897Article in journal (Refereed)
    Abstract [en]

    Altered fucosylation of glycoproteins is associated with development of hepatocellular carcinoma (HCC). Lectins have been commonly used to assay changes in fucosylation of plasma glycoproteins. In the present study a recombinantly engineered form of the fucose binding lectin Aleuria aurantia (AAL) consisting of a single binding site for fucose (S2), was used to construct a reverse lectin ELISA method. Microtiter plates coated with the S2 lectin were used to capture glycoproteins from plasma samples followed by antibody detection of S2-bound fucosylated alpha 1-acid glycoprotein (S2-bound AGP). The method was used to compare the level of S2-bound AGP in serum samples from a small cohort of patients with hepatitis, cirrhosis or HCC. Using the reverse S2 lectin ELISA it was shown that the levels of S2-bound AGP was significantly higher in HCC patients compared to non-cancer patients and that there was also a significant elevation of S2-bound AGP in HCC patients compared to cirrhosis patients. There was no correlation between the level of S2-bound AGP and total AGP concentration. The performance of S2-bound AGP in differentiating HCC from cirrhosis samples or hepatitis samples were compared to other markers. A combination of S2-bound AGP, alpha-fetoprotein and AGP concentration showed performances giving area under receiver operating curves of 0.87 and 0.95 respectively.

  • 101958.
    Åström, Freddie
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, The Institute of Technology.
    A Variational Approach to Image Diffusion in Non-Linear Domains2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Image filtering methods are designed to enhance noisy images captured in situations that are problematic for the camera sensor. Such noisy images originate from unfavourable illumination conditions, camera motion, or the desire to use only a low dose of ionising radiation in medical imaging. Therefore, in this thesis work I have investigated the theory of partial differential equations (PDE) to design filtering methods that attempt to remove noise from images. This is achieved by modeling and deriving energy functionals which in turn are minimized to attain a state of minimum energy. This state is obtained by solving the so called Euler-Lagrange equation. An important theoretical contribution of this work is that conditions are put forward determining when a PDE has a corresponding energy functional. This is in particular described in the case of the structure tensor, a commonly used tensor in computer vision.A primary component of this thesis work is to model adaptive image filtering such that any modification of the image is structure preserving, but yet is noise suppressing. In color image filtering this is a particular challenge since artifacts may be introduced at color discontinuities. For this purpose a non-Euclidian color opponent transformation has been analysed and used to separate the standard RGB color space into uncorrelated components.A common approach to achieve adaptive image filtering is to select an edge stopping function from a set of functions that have proven to work well in the past. The purpose of the edge stopping function is to inhibit smoothing of image features that are desired to be retained, such as lines, edges or other application dependent characteristics. Thus, a step from ad-hoc filtering based on experience towards an application-driven filtering is taken, such that only desired image features are processed. This improves what is characterised as visually relevant features, a topic which this thesis covers, in particular for medical imaging.The notion of what are relevant features is a subjective measure may be different from a layman's opinion compared to a professional's. Therefore, we advocate that any image filtering method should yield an improvement not only in numerical measures but also a visual improvement should be experienced by the respective end-user

    List of papers
    1. Color Persistent Anisotropic Diffusion of Images
    Open this publication in new window or tab >>Color Persistent Anisotropic Diffusion of Images
    2011 (English)In: Image Analysis / [ed] Anders Heyden, Fredrik Kahl, Heidelberg: Springer, 2011, p. 262-272Conference paper, Published paper (Refereed)
    Abstract [en]

    Techniques from the theory of partial differential equations are often used to design filter methods that are locally adapted to the image structure. These techniques are usually used in the investigation of gray-value images. The extension to color images is non-trivial, where the choice of an appropriate color space is crucial. The RGB color space is often used although it is known that the space of human color perception is best described in terms of non-euclidean geometry, which is fundamentally different from the structure of the RGB space. Instead of the standard RGB space, we use a simple color transformation based on the theory of finite groups. It is shown that this transformation reduces the color artifacts originating from the diffusion processes on RGB images. The developed algorithm is evaluated on a set of real-world images, and it is shown that our approach exhibits fewer color artifacts compared to state-of-the-art techniques. Also, our approach preserves details in the image for a larger number of iterations.

    Place, publisher, year, edition, pages
    Heidelberg: Springer, 2011
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 6688
    Keywords
    Non-linear diffusion, color image processing, perceptual image quality
    National Category
    Information Systems Computer Vision and Robotics (Autonomous Systems)
    Identifiers
    urn:nbn:se:liu:diva-68999 (URN)10.1007/978-3-642-21227-7_25 (DOI)978-3-642-21226-0 (ISBN)978-3-642-21227-7 (ISBN)
    Conference
    The 17th Scandinavian Conference on Image Analysis, 23-27 May 2011, Ystad Sweden
    Note

    Original Publication: Åström Freddie, Felsberg Michael and Lenz Reiner, Color Persistent Anisotropic Diffusion of Images, 2011, Image Analysis, SCIA conference, 23-27 May 2011, Ystad Sweden, 262-272. http://dx.doi.org/10.1007/978-3-642-21227-7_25 Copyright: Springer

    Available from: 2011-06-17 Created: 2011-06-15 Last updated: 2018-02-06Bibliographically approved
    2. On Tensor-Based PDEs and their Corresponding Variational Formulations with Application to Color Image Denoising
    Open this publication in new window or tab >>On Tensor-Based PDEs and their Corresponding Variational Formulations with Application to Color Image Denoising
    2012 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    The case when a partial differential equation (PDE) can be considered as an Euler-Lagrange (E-L) equation of an energy functional, consisting of a data term and a smoothness term is investigated. We show the necessary conditions for a PDE to be the E-L equation for a corresponding functional. This energy functional is applied to a color image denoising problem and it is shown that the method compares favorably to current state-of-the-art color image denoising techniques.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2012
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 7574
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-79603 (URN)10.1007/978-3-642-33712-3_16 (DOI)978-3-642-33711-6 (ISBN)978-3-642-33712-3 (ISBN)
    Conference
    ECCV 2012: 12th European Conference on Computer Vision, 7-12 October, Firenze, Italy
    Projects
    NACIPGARNICSELLIIT
    Available from: 2012-08-10 Created: 2012-08-10 Last updated: 2017-06-01Bibliographically approved
    3. Targeted Iterative Filtering
    Open this publication in new window or tab >>Targeted Iterative Filtering
    2013 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    The assessment of image denoising results depends on the respective application area, i.e. image compression, still-image acquisition, and medical images require entirely different behavior of the applied denoising method. In this paper we propose a novel, nonlinear diffusion scheme that is derived from a linear diffusion process in a value space determined by the application. We show that application-driven linear diffusion in the transformed space compares favorably with existing nonlinear diffusion techniques. 

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2013
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349 ; 7893
    National Category
    Signal Processing
    Identifiers
    urn:nbn:se:liu:diva-89674 (URN)10.1007/978-3-642-38267-3_1 (DOI)978-3-642-38266-6 (ISBN)978-3-642-38267-3 (ISBN)
    Conference
    Fourth International Conference on Scale Space and Variational Methods in Computer Vision (SSVM 2013), 2-6 June 2013, Schloss Seggau, Graz region, Austria
    Projects
    VIDIGARNICSSM10-002BILDLAB
    Available from: 2013-04-03 Created: 2013-03-01 Last updated: 2018-01-26Bibliographically approved
  • 101959.
    Åström, Freddie
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Variational Tensor-Based Models for Image Diffusion in Non-Linear Domains2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation addresses the problem of adaptive image filtering.

    Although the topic has a long history in the image processing community, researchers continuously present novel methods to obtain ever better image restoration results.

    With an expanding market for individuals who wish to share their everyday life on social media, imaging techniques such as compact cameras and smart phones are important factors. Naturally, every producer of imaging equipment desires to exploit cheap camera components while supplying high quality images. One step in this pipeline is to use sophisticated imaging software including, e.g., noise reduction to reduce manufacturing costs, while maintaining image quality.

    This thesis is based on traditional formulations such as isotropic and tensor-based anisotropic diffusion for image denoising. The difference from main-stream denoising methods is that this thesis explores the effects of introducing contextual information as prior knowledge for image denoising into the filtering schemes. To achieve this, the adaptive filtering theory is formulated from an energy minimization standpoint. The core contributions of this work is the introduction of a novel tensor-based functional which unifies and generalises standard diffusion methods. Additionally, the explicit Euler-Lagrange equation is derived which, if solved, yield the stationary point for the minimization problem. Several aspects of the functional are presented in detail which include, but are not limited to, tensor symmetry constraints and convexity. Also, the classical problem of finding a variational formulation to a given tensor-based partial differential equation is studied.

    The presented framework is applied in problem formulation that includes non-linear domain transformation, e.g., visualization of medical images.

    Additionally, the framework is also used to exploit locally estimated probability density functions or the channel representation to drive the filtering process.

    Furthermore, one of the first truly tensor-based formulations of total variation is presented. The key to the formulation is the gradient energy tensor, which does not require spatial regularization of its tensor components. It is shown empirically in several computer vision applications, such as corner detection and optical flow, that the gradient energy tensor is a viable replacement for the commonly used structure tensor. Moreover, the gradient energy tensor is used in the traditional tensor-based anisotropic diffusion scheme. This approach results in significant improvements in computational speed when the scheme is implemented on a graphical processing unit compared to using the commonly used structure tensor.

  • 101960.
    Åström, Freddie
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    A Tensor Variational Formulation of Gradient Energy Total Variation2015In: ENERGY MINIMIZATION METHODS IN COMPUTER VISION AND PATTERN RECOGNITION, EMMCVPR 2015, Springer Berlin/Heidelberg, 2015, Vol. 8932, p. 307-320Conference paper (Refereed)
    Abstract [en]

    We present a novel variational approach to a tensor-based total variation formulation which is called gradient energy total variation, GETV. We introduce the gradient energy tensor into the GETV and show that the corresponding Euler-Lagrange (E-L) equation is a tensor-based partial differential equation of total variation type. Furthermore, we give a proof which shows that GETV is a convex functional. This approach, in contrast to the commonly used structure tensor, enables a formal derivation of the corresponding E-L equation. Experimental results suggest that GETV compares favourably to other state of the art variational denoising methods such as extended anisotropic diffusion (EAD) and total variation (TV) for gray-scale and colour images.

  • 101961.
    Åström, Freddie
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    On Tensor-Based PDEs and their Corresponding Variational Formulations with Application to Color Image Denoising2012Conference paper (Refereed)
    Abstract [en]

    The case when a partial differential equation (PDE) can be considered as an Euler-Lagrange (E-L) equation of an energy functional, consisting of a data term and a smoothness term is investigated. We show the necessary conditions for a PDE to be the E-L equation for a corresponding functional. This energy functional is applied to a color image denoising problem and it is shown that the method compares favorably to current state-of-the-art color image denoising techniques.

  • 101962.
    Åström, Freddie
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Science & Engineering.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Science & Engineering.
    On the Choice of Tensor Estimation for Corner Detection, Optical Flow and Denoising2015In: COMPUTER VISION - ACCV 2014 WORKSHOPS, PT II / [ed] C.V. Jawahar and Shiguang Shan, Springer, 2015, Vol. 9009, p. 15p. 16-30Conference paper (Refereed)
    Abstract [en]

    Many image processing methods such as corner detection,optical flow and iterative enhancement make use of image tensors. Generally, these tensors are estimated using the structure tensor. In this work we show that the gradient energy tensor can be used as an alternativeto the structure tensor in several cases. We apply the gradient energy tensor to common image problem applications such as corner detection, optical flow and image enhancement. Our experimental results suggest that the gradient energy tensor enables real-time tensor-based image enhancement using the graphical processing unit (GPU) and we obtain 40% increase of frame rate without loss of image quality.

  • 101963.
    Åström, Freddie
    et al.
    Heidelberg University, Germany.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Mapping-Based Image Diffusion2017In: Journal of Mathematical Imaging and Vision, ISSN 0924-9907, E-ISSN 1573-7683, Vol. 57, no 3, p. 293-323Article in journal (Refereed)
    Abstract [en]

    In this work, we introduce a novel tensor-based functional for targeted image enhancement and denoising. Via explicit regularization, our formulation incorporates application-dependent and contextual information using first principles. Few works in literature treat variational models that describe both application-dependent information and contextual knowledge of the denoising problem. We prove the existence of a minimizer and present results on tensor symmetry constraints, convexity, and geometric interpretation of the proposed functional. We show that our framework excels in applications where nonlinear functions are present such as in gamma correction and targeted value range filtering. We also study general denoising performance where we show comparable results to dedicated PDE-based state-of-the-art methods.

  • 101964.
    Åström, Freddie
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Felsberg, Michael
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lundström, Claes
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Targeted Iterative Filtering2013Conference paper (Refereed)
    Abstract [en]

    The assessment of image denoising results depends on the respective application area, i.e. image compression, still-image acquisition, and medical images require entirely different behavior of the applied denoising method. In this paper we propose a novel, nonlinear diffusion scheme that is derived from a linear diffusion process in a value space determined by the application. We show that application-driven linear diffusion in the transformed space compares favorably with existing nonlinear diffusion techniques. 

  • 101965.
    Åström, Freddie
    et al.
    Heidelberg Collaboratory for Image Processing Heidelberg University Heidelberg, Germany.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Scharr, Hanno
    BG-2: Plant Sciences Forschungszentrum Jülich 52425, Jülich, Germany.
    Adaptive sharpening of multimodal distributions2015In: Colour and Visual Computing Symposium (CVCS), 2015 / [ed] Marius Pedersen and Jean-Baptiste Thomas, IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    In this work we derive a novel framework rendering measured distributions into approximated distributions of their mean. This is achieved by exploiting constraints imposed by the Gauss-Markov theorem from estimation theory, being valid for mono-modal Gaussian distributions. It formulates the relation between the variance of measured samples and the so-called standard error, being the standard deviation of their mean. However, multi-modal distributions are present in numerous image processing scenarios, e.g. local gray value or color distributions at object edges, or orientation or displacement distributions at occlusion boundaries in motion estimation or stereo. Our method not only aims at estimating the modes of these distributions together with their standard error, but at describing the whole multi-modal distribution. We utilize the method of channel representation, a kind of soft histogram also known as population codes, to represent distributions in a non-parametric, generic fashion. Here we apply the proposed scheme to general mono- and multimodal Gaussian distributions to illustrate its effectiveness and compliance with the Gauss-Markov theorem.

  • 101966.
    Åström, Freddie
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Koker, Rasit
    Engineering Faculty Esentepe Kampus, Computer Engineering Department, Sakarya University, Turkey.
    A parallel neural network approach to prediction of Parkinson´s Disease2011In: Expert systems with applications, ISSN 0957-4174, E-ISSN 1873-6793, Vol. 38, no 10, p. 12470-12474Article in journal (Refereed)
    Abstract [en]

    Recently the neural network based diagnosis of medical diseases has taken a great deal of attention. In this paper a parallel feed-forward neural network structure is used in the prediction of Parkinson’s Disease. The main idea of this paper is using more than a unique neural network to reduce the possibility of decision with error. The output of each neural network is evaluated by using a rule-based system for the final decision. Another important point in this paper is that during the training process, unlearned data of each neural network is collected and used in the training set of the next neural network. The designed parallel network system significantly increased the robustness of the prediction. A set of nine parallel neural networks yielded an improvement of 8.4% on the prediction of Parkinson’s Disease compared to a single unique network. Furthermore, it is demonstrated that the designed system, to some extent, deals with the problems of imbalanced data sets.

  • 101967.
    Åström, Freddie
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Zografos, Vasileios
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Felsberg, Michael
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Density Driven Diffusion2013In: 18th Scandinavian Conferences on Image Analysis, 2013, 2013, p. 718-730Conference paper (Refereed)
    Abstract [en]

    In this work we derive a novel density driven diffusion scheme for image enhancement. Our approach, called D3, is a semi-local method that uses an initial structure-preserving oversegmentation step of the input image.  Because of this, each segment will approximately conform to a homogeneous region in the image, allowing us to easily estimate parameters of the underlying stochastic process thus achieving adaptive non-linear filtering. Our method is capable of producing competitive results when compared to state-of-the-art methods such as non-local means, BM3D and tensor driven diffusion on both color and grayscale images.

  • 101968.
    Åström, Henning
    Linköping University, Department of Thematic Studies.
    Ett hållbart kretslopp?: Förutsättningar för återföring av näringsämnen i humanavlopp till odlad mark; Norrköpings kommun som exempel2005Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    The study examins if returning of nutrients, mainly the macronutriens nitrogen and phosphorus, from sewage in the municipality of Norrköping can be done in way that corresponds to natural scientiffic principals of circulation of material.

    The issue of returning of nutrients and the presentation of the problem are of great importance when the fluxes of today are leading to a waste of resources and the environmental problem eutrophication. The reason for nutrients are not recycled must be some sort of incapability of the involved actors to deal with the problem.

    The study analyses perspectives of different actors. The actors are described in a national as well as a more focused municipal perspective. This is because of the part that the municipality is playing implies that they are ultimately responsible for the shaping of the sewersystem. The ones that are acting in relation to the municipality have because of this been examined thru interviews with representatives for the actors.

    The study is thus a casestudy where the municipality of Norrköping is studied and the actors chosen is the sewage treatment plant of Slottshagen, the county administrative board of Östergötland, a branch of the Swedish farmers cooperation “Lantmännen” and the health and environment office of the municipality. The empirical material shows that the actors are not adopting a recycle-perspective and that they tend to adopt an economical perspective when they deal with the problem. This can cause problems in a ecological context and obstruct a positive development in dealing with environmental problems. The study relates the results and the responsibility of the actors to the common view of the way of dealing with environmental issues that is recommended thru the Swedish environmental law.

  • 101969.
    Åström, I. Maria
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Differences between students in Swedish compulsory schools with integrated andsubject-specific Science education in PISA 2006Manuscript (Other academic)
    Abstract [en]

    This study is a comparison between three groups of teaching organisations in Sweden that work either with integrated Science, subject-specific Science or a mixed form of the two. Comparison is made between the students’ total Science scores in the PISA 2006 study and the three scores in student competency regarding Knowledge in Science and Knowledge about Science. This comparison is made both at the individual and school level. There are differences between students with integrated Science education and students with subjectspecific Science. These differences are found both in the total scores and in some of the subscores. An even more striking difference is found between boys and girls in the different groups. There are big differences in test scores for girls with integrated Science as compared to girls with subject-specific Science; this difference is almost nonexistent for boys. Some caution must be shown in drawing conclusions from this finding, however, since girls’ and boys’ groups differ in mean ESCS, and there are differences in the percentage of students who speak another language at home than Swedish. Some plausible explanations for the differences are discussed based on inferences from other studies.

  • 101970.
    Åström, I. Maria
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    En Delphi-studie av initierade brukaresuppfattningar om karaktärer av integreradnaturvetenskap i senare delen av svensk grundskola2009In: Didaktisk Tidskrift, ISSN 1101-7686, Vol. 19, no 3, p. 114-132Article in journal (Other academic)
    Abstract [en]

    Den här studien undersöker hur experter, väl insatta i den svenska debatten om integrerad NO uppfattar vad integrerad NO är, hur den tillämpas och vilka skäl som finns för att undervisa integrerat i NO istället för att undervisa ämnesuppdelat. Diskussionen om integrerad eller ämnesuppdelad NO hade en kulmen på 1980-talet i Sverige som gav två varianter att undervisa NO på i grundskolan, antingen som ett ämne eller som tre ämnen, biologi, kemi och fysik. Dessa varianter finns åtminstone som två likvärdiga sätt att gradera betyg på. Nu är det aktuellt att ta bort denna möjlighet att sätta NO-betyg eller biologi-, fysik- och kemibetyg, vilket gör det intressant att undersöka hur idén om vad integrerad och ämnesuppdelad NO-undervisning har för likheter och skillnader. Undersökningen är genomförd som en Delphistudie, där de tillfrågade deltagarna anonymt har värderat 30 påståenden om integrerad och ämnesuppdelad undervisning i ett första steg. Svaren sammanställdes med medelvärden och medianer och presenterades för deltagarna i en andra enkätomgång. Informanterna erbjöds möjlighet att ändra sina svar efter att ha tagit del i de övriga deltagarnas värderingar av påståendena i form av centralmått på frågorna. Resultatet av den första undersökningsomgången redovisas i tabell där informanternas sammanlagda bedömning eller skattning av påståendena redovisas. Informanternas svar diskuteras och jämförs med den teori som ursprungligen använts för att konstruera frågorna. Metodiska frågor i samband med undersökningen diskuteras också.

  • 101971.
    Åström, I. Maria
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Integrated and Subject-specific: An empirical exploration of Science education in Swedish compulsory school2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is an explorative experimental study in two parts of different ways of organising Science education in the Swedish context. The first study deals with the question if students attain higher scores on test results if they have been working with integrated Science compared to subject-specific Science i.e. Biology, Chemistry and Physics. The second study concerns the similarities and differences between integrated Science education and Science education in Biology, Chemistry and Physics, especially in the teaching organisation.

    The introduction describes the nature of integrated curriculum, what integrated learning is, issues about integrated Science education, in what way integration is carried out, between subjects or within subjects, what the opposite to integrated Science is (here named as subjectspecific science education) in the Swedish context and what the Swedish curriculum has to say about integrated Science. Previous studies in integrated curriculum looking at students’ results are referred to, and it is argued for the use of the OECD’s PISA assessment instrument in this study.

    The thesis consists of two studies, one quantitative and one qualitative, within the above framework. The quantitative study is an attempt to find differences in scores on students’ written results on a large-scale assessment in scientific literacy between students studying in different organisations of Science education. The qualitative study is an attempt to describe differences at classroom level between integrated Science and subject-specific Science. This gives a quite rich description of four schools (cases) in a small town and how they organise their teaching integrated or subject-specific.

    No differences in students’ results between different Science organisations were found in the quantitative study in this thesis. Possible explanations for the lack of differences in students’ results are discussed in the article. An additional investigation that attempts to test the variable used in the quantitative study is carried out in the thesis, with an attempt to sharpen the teacher organisation variable. This is done to find out if it is possible that there can be found differences with the sharpened variable.

    The qualitative study gives a glimpse of some differences in the implemented curriculum between schools working with integrated Science education and a school that works subjectspecifically. The teachers do the overall lesson plans in different ways according to which organisation according to integrated or subject-specific Science they work with. When asked in a survey what kind of Science organisation they have, students from the four schools studied answered differently between schools and also, sometimes, within the same school. A further analysis of this second study is carried out by defining a conceptual framework used as structure and a possible explanation for differences between students’ views and teachers’ views on the organisation of Science education. This latter analysis tries to give an enriched description in mainly the two levels of the implemented and attained curricula, and tries to discuss the difference in students’ attained curriculum.

    A final discussion concludes the thesis and concerns an elaboration of the results of the thesis, problems with the main variable involved in the two studies and the possibility that the teacher actions effects also the magnitude of students’ achievement on tests.

    List of papers
    1. Using hierarchical linear models to test differences in Swedish results from OECD’sPISA 2003: Integrated and subject-specific science education
    Open this publication in new window or tab >>Using hierarchical linear models to test differences in Swedish results from OECD’sPISA 2003: Integrated and subject-specific science education
    2007 (English)In: NorDiNa: Nordic Studies in Science Education, ISSN 1504-4556, E-ISSN 1894-1257, Vol. 3, no 2, p. 121-131Article in journal (Refereed) Published
    Abstract [en]

    The possible effects of different organisations of the science curriculum in schools participating in PISA 2003 are tested with a hierarchical linear model (HLM) of two levels. The analysis is based on science results. Swedish schools are free to choose how they organise the science curriculum. They may choose to work subject-specifically (with Biology, Chemistry and Physics), integrated (with Science) or to mix these two. In this study, all three ways of organising science classes in compulsory school are present to some degree. None of the different ways of organising science education displayed statistically significant better student results in scientific literacy as measured in PISA 2003. The HLM model used variables of gender, country of birth, home language, preschool attendance, an economic, social and cultural index as well as the teaching organisation.

    National Category
    Pedagogy
    Identifiers
    urn:nbn:se:liu:diva-15473 (URN)
    Available from: 2008-11-11 Created: 2008-11-11 Last updated: 2017-12-14Bibliographically approved
    2. Integrated and subject-specific Science education: Teachers’ and students’ views
    Open this publication in new window or tab >>Integrated and subject-specific Science education: Teachers’ and students’ views
    (English)Manuscript (Other academic)
    Abstract [en]

    This study concerns the views of teachers’ and students’ regarding Science education. The teachers and students are all from four schools in the same small town in Sweden. The teachers’ views of Science lessons focused on how to plan lessons and organise content. The students’ views focused on three questions concerning the integration of science. The study is based on several data collections: interviews with and observations of teachers, a school survey and student questionnaires. The teacher interviews were analysed with regard to integrated and subject-specific Science education and the students’ questionnaires were analysed with statistical methods. The four schools in this study may be categorised as two integrated schools, one subject-specific and one mixed school. The students’ views of subjectspecific and integrated Science did not completely coincide with the teachers’ views. Teachers and students agreed on that they did integrated education in only one out of the four schools.

    Keywords
    Science education, teachers’ and students’ views, integrated and subject specific Science
    National Category
    Pedagogy
    Identifiers
    urn:nbn:se:liu:diva-15475 (URN)
    Available from: 2008-11-11 Created: 2008-11-11 Last updated: 2010-01-14Bibliographically approved
  • 101972.
    Åström, I. Maria
    et al.
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Karl-Göran , Karlsson
    Department of Engineering, Physics and Mathematics, Mid Sweden University.
    Integrated and subject-specific Science education: Teachers’ and students’ viewsManuscript (Other academic)
    Abstract [en]

    This study concerns the views of teachers’ and students’ regarding Science education. The teachers and students are all from four schools in the same small town in Sweden. The teachers’ views of Science lessons focused on how to plan lessons and organise content. The students’ views focused on three questions concerning the integration of science. The study is based on several data collections: interviews with and observations of teachers, a school survey and student questionnaires. The teacher interviews were analysed with regard to integrated and subject-specific Science education and the students’ questionnaires were analysed with statistical methods. The four schools in this study may be categorised as two integrated schools, one subject-specific and one mixed school. The students’ views of subjectspecific and integrated Science did not completely coincide with the teachers’ views. Teachers and students agreed on that they did integrated education in only one out of the four schools.

  • 101973.
    Åström, Jan
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Introductory greeting behaviour in relation to sex, age, physical characteristics, attitudes, personality, and psychopathology: Approaches by interviews, observations, and experiments1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The overall aim of this thesis was to elucidate, through interviews, observations and experiments, elements of the introductory greeting, such as sex, age, physical characteristics, personality, and psychopathology, in a psychotherapeutic situation. As an introductory greeting it was considered here the ftrst occasion the therapist and the patient greet each other in the waiting room.

    Papers I - III in the thesis deal with the construction of an interview questionnaire, its psychometric properties and use among psychotherapists (n= 79) and psychotherapeutic out-patients (n= 50). Psychotherapists were interviewed about their attitudes towards and observations of nonverbal communication in an introductory greeting situation. The results from the interview were related to therapists' background variables such as sex, age, clinical experience, and theoretical orientation. Psychotherapeutic out-patients were interviewed in a similar way.

    Paper IV deals with rated handshaking in psychiatric patients (n= 29) related to personality traits according to an abbreviated scale of Minnesota Multiphasic Personality Inventory (MMPI), the Faschingbauer Abbreviated MMPI (FAM), clinical diagnoses, and psychosocial functioning. Four handshaking variables were rated independently by two raters in a ftve steps scale: the perceived Consistency, Temperature, Dryness and Strength of the hand. The interrater reliability was satisfactory.

    Papers V - VI deal with the greeting behaviour of healthy subjects (n= 50) in an experimental setting. The introductory greeting behaviour was fthned and nonverbal immediacy behaviour (NVIB) analysed in the approaching and close salutation phases together with the handshaking variables, and related to some back-ground variables such as sex, age, body height, vigour of the hand, and personality traits.

    The interview questionnaire possessed satisfactory psychometric qualities (Paper I). Female psychotherapists paid signiftcantly greater importance to 'face communication in the greeting situation compared to male therapists. Great importance attached to nonverbal communication in psychotherapy was related to being well-kept and to perform correctly in front of the patient, to establish direct communication in the greeting situation, and to frequent work in psychotherapy and an eclectic psychotherapeutic orientation (Paper II). The importance of the face as a mean of contact in nonverbal communication was particularly stressed by female, mainly older patients who believed that 'face communication' covers more than 50 percent of the total communication in human interactions (Paper III).

    The findings in psychiatric patients (Paper IV) indicate that the handshaking procedure may transmit information about personality make-up. Low temperature and humidity of the palmar skin were related to social introversion, depression, and tendency to symptom enhancement mainly in women.

    The reliability and stability over time of nonverbal immediacy behaviour (physic and psychological closeness) and handshake characteristics in the experimental study were on the whole satisfactory (Papers V - VI). Women displayed greater intimacy behaviour (less physical distance and presence of smile) in their greeting behaviour than males. Statistically signiftcant correlations between variables of handshaking and personality traits were noted. Strength of the hand in particular was related to extraversion loaded traits as dominance, aggression and exhibition.

  • 101974.
    Åström, Jan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry.
    Paulin, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Thorell, Lars-Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Inner images and delineations of parental figures reported by psychotherapeutic outpatients2006In: Perceptual and Motor Skills, ISSN 0031-5125, E-ISSN 1558-688X, Vol. 103, no 3, p. 931-945Article in journal (Refereed)
    Abstract [en]

    Psychotherapeutic outpatients (10 men, 20 women) were tested with the Inner Images of Parental Figures. Each subject imagined first his mother and then his father. Questions were asked about size, look, and spatial and emotional distance of the imagined parent. The patient was then asked to describe the personality of each parent by underlining at least 20 of 85 adjectives in a list called Family Climate Scale. This originally consisted of four factors, Closeness, Spontaneity, Distance, and Chaos, but the two administered were Factor I (positive traits) and Factor II (negative traits). Emotional distance correlated positively with Factor I and negatively with Factor II. For the maternal figure there was a correlation with distance in metres and Factor I scores. The Inner Images of Parental Figures may be a valuable complement in psychotherapy, mapping out emotional relations between patients and their parents. © Perceptual and Motor Skills 2006.

  • 101975.
    Åström, Jan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry.
    Thorell, Lars-Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Graphometric variables of one's signature: I. Basic measures2007In: Perceptual and Motor Skills, ISSN 0031-5125, E-ISSN 1558-688X, Vol. 105, no 3 I, p. 733-752Article in journal (Refereed)
    Abstract [en]

    This study focused on statistical properties and interrelationships of graphometric variables of the signatures of outpatients, 100 men and 119 women, remitted from somatic and psychiatric clinics for possible psychotherapy or for tests of IQ, personality, or brain lesions. The patients' signature on test forms were used. The type of handwriting was classified into Common, Print and Block letters, quantified in breadth, length, and area and grades of slant of minuscules ("lower-case letters") and majuscules ("upper- case"). Analysis indicated sex and age played roles in style of handwriting and size of letters, writing styles differed on most graphometric variables, and meaningful patterns of interrelationships among graphometric variables were specified by factor analysis. © Perceptual and Motor Skills 2007.

  • 101976.
    Åström, Jan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Psychiatry .
    Thorell, Lars-Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Psychiatry . Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Graphometric variables of one's signature: II. Correlations with measures of perception, cognitive function, and personality2008In: Perceptual and Motor Skills, ISSN 0031-5125, E-ISSN 1558-688X, Vol. 107, no 1, p. 197-221Article in journal (Refereed)
    Abstract [en]

    This study focused on interrelations between graphometric variables of the signature and measures of perception, cognitive function, and personality. Signatures from a sample of psychiatric and somatic outpatients (N=205) were analyzed into 23 graphometric variables and correlated with tests of IQ, cognitive and perceptual function, and personality. The results of a factor analysis of the graphometric, perceptual, and cognitive variables were very much like results from previous studies. Relationships with the graphometric variables can be described in five categories of intelligence, psychomotility, flexibility and speed of closure, and personality. Graphometric signs of Extraversion and Neuroticism were identified, and the two capitals in the signature indicated different psychological meanings. Measurements of the signature offered important personality information. © Perceptual and Motor Skills 2008.

  • 101977.
    Åström, Jennie
    Linköping University, Department of Social and Welfare Studies.
    Fångarna, fängelset och motståndet2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Den här uppsatsen behandlar kriminalvården utifrån fångarnas perspektiv som den skildras i tidningen Kåkbladet, som är skriven av fångar i Sverige och som även i första hand riktar sig till fångar. De intagna skribenternas upplevelser av kriminalvården läggs fram genom en diskursanalys av Kåkbladet. Analysen visar hur fångarna framställer sig själva och den personal som dagligen arbetar med dem i fängelset samt vilken bild fångarna målar upp av kriminalvården som institution. Livet i fängelset skildras i texterna som präglat av kontroll och fångarna förmedlar en upplevd maktlöshet inför sin situation. I samband med denna upplevelse skapas i texterna strategier för motmakt där fångarna genom gemensamt motstånd gör anspråk på att sätta sig upp mot kontrollen. Uppsatsen utgår från ett socialkonstruktivistiskt synsätt där den verklighet som framställs i Kåkbladet ses som en konstruktion av talet. Goffmans teori om totala institutioner används tillsammans med annan forskning om fängelset och totala institutioner som ett teoretiskt ramverk för att fördjupa förståelsen av analysresultatet.

  • 101978.
    Åström, Jennie
    Linköping University, Department of Social and Welfare Studies.
    Tvåsamhället: Om att förhålla sig till normer som skaver2008Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study focuses on single peoples construction of their lifes in relation to normative heterosexual coupledom. It is based on five interviews made with single women and men at the age of 24 to 51 who live by themselves. The queer theory which puts the heteronormativity in question is used as a theoretical framework. Discourse psychology functions as an analytic approach. It focuses on the use of language in the construction of reality in a world of determinant discourses. The thesis shows how the life of singles is made understandable where the interviewee´s constructs their reality by either creating their own life's as possible ways of living and distance themselves from coupledom or by striving for the twosome way of living. This is done by a construction of gender and age performance as different in the single and the twosome life. It also shows paradoxes where discourses of advantage independence meet discourses that construct twosome relationships as the only place for the development of real masculinity or of a special form of preferable femininity. The construction of gender and age as performed different in the single and the couple life provides an understanding of the interviewee's creation of self-image in relation to normative heterosexual coupledom.

  • 101979.
    Åström, Karl J.
    et al.
    Lund University, Sweden.
    Benveniste, Albert
    INRIA, France.
    Caines, Peter E.
    INRIA, France.
    Cohen, Guy
    INRIA, France.
    Ljung, Lennart
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Facing the Challenge of Computer Science in the Industrial Applications of Control1992Report (Other academic)
    Abstract [en]

    Control, signal processing, and more generally "systems" industries ignore the boundaries we have in the academic world between control, signal processing, and computer sciences. Industries think of "hardware" (electronics or computers) and "software", making little distinction between algorithms development and implementation of them. Acting as a chariman of the IFAC Technical Committee on Theory for the triennium 1990-1993, Albert Benveniste proposed in the fall of 1989 this project to investigate some fundamental questions raised by the above mentioned facts. Since CDC'90 this has been approved as a joint IEEE/CSS-IFAC project managed by the above listed group of people. A detailed progress report of the project has been written in March 20, 1991, followed by a brief update in October 19, 1991. This is summary of the conclusions of the report. Additional detailed information on the project is found in the bibliography.

  • 101980.
    Åström, Karl Johan
    et al.
    Lund Institute of Technology, Sweden.
    Borisson, U
    Gränges Data, Sweden.
    Ljung, Lennart
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Wittenmark, Björn
    Lund Institute of Technology.
    Theory and Applications of Self Tuning Regulators1977In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 13, no 5, p. 457-476Article in journal (Refereed)
    Abstract [en]

    This paper reviews work on self-tuning regulators. The regulator algorithms, their theory and industrial applications are reviewed. The paper is expository—the major ideas are covered but detailed analysis is given elsewhere.

  • 101981.
    Åström, Karsten
    Linköping University, Department of Social and Welfare Studies, Social Work. Linköping University, Faculty of Arts and Sciences.
    Parallel norm creating processes2013In: Social and Legal Norms: Towards a Socio-legal Understanding of Normativity / [ed] Matthias Baier, Farnham: Ashgate, 2013, 1Chapter in book (Other academic)
  • 101982.
    Åström, Maria
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Arts and Sciences.
    Betyg och bedömning i NO2012In: Betyg i teori och praktik: ämnesdidaktiska perspektiv på bedömning i grundskola och gymnasium / [ed] Nordgren, Kenneth, Odenstad, Christina och Samuelsson, Johan, Malmö: Gleerups Utbildning AB, 2012, 2, p. 131-140Chapter in book (Other (popular science, discussion, etc.))
  • 101983.
    Åström, Maria
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Defining Integrated Science Education and Putting It to Test2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis is made up by four studies, on the comprehensive theme of integrated and subjectspecific science education in Swedish compulsory school. A literature study on the matter is followed by an expert survey, then a case study and ending with two analyses of students’ science results from PISA 2003 and PISA 2006. The first two studies explore similarities and differences between integrated and subject-specific science education, i. e. Science education and science taught as Biology, Chemistry and Physics respectively. The two following analyses of PISA 2003 and PISA 2006 data put forward the question whether there are differences in results of students’ science literacy scores due to different types of science education.

    The expert survey compares theories of integration to the Swedish science education context. Also some difference in intention, in the school case study, some slight differences in the way teachers plan the science education are shown, mainly with respect to how teachers involve students in their planning.

    The statistical analysis of integrated and subject-specific science education comparing students’ science results from PISA 2003 shows no difference between students or between schools. The analysis of PISA 2006, however, shows small differences between girls’ results with integrated and subject-specific science education both in total scores and in the three scientific literacy competencies. No differences in boys’ results are shown on different science educations.

    List of papers
    1. En Delphi-studie av initierade brukaresuppfattningar om karaktärer av integreradnaturvetenskap i senare delen av svensk grundskola
    Open this publication in new window or tab >>En Delphi-studie av initierade brukaresuppfattningar om karaktärer av integreradnaturvetenskap i senare delen av svensk grundskola
    2009 (Swedish)In: Didaktisk Tidskrift, ISSN 1101-7686, Vol. 19, no 3, p. 114-132Article in journal (Other academic) Published
    Abstract [en]

    Den här studien undersöker hur experter, väl insatta i den svenska debatten om integrerad NO uppfattar vad integrerad NO är, hur den tillämpas och vilka skäl som finns för att undervisa integrerat i NO istället för att undervisa ämnesuppdelat. Diskussionen om integrerad eller ämnesuppdelad NO hade en kulmen på 1980-talet i Sverige som gav två varianter att undervisa NO på i grundskolan, antingen som ett ämne eller som tre ämnen, biologi, kemi och fysik. Dessa varianter finns åtminstone som två likvärdiga sätt att gradera betyg på. Nu är det aktuellt att ta bort denna möjlighet att sätta NO-betyg eller biologi-, fysik- och kemibetyg, vilket gör det intressant att undersöka hur idén om vad integrerad och ämnesuppdelad NO-undervisning har för likheter och skillnader. Undersökningen är genomförd som en Delphistudie, där de tillfrågade deltagarna anonymt har värderat 30 påståenden om integrerad och ämnesuppdelad undervisning i ett första steg. Svaren sammanställdes med medelvärden och medianer och presenterades för deltagarna i en andra enkätomgång. Informanterna erbjöds möjlighet att ändra sina svar efter att ha tagit del i de övriga deltagarnas värderingar av påståendena i form av centralmått på frågorna. Resultatet av den första undersökningsomgången redovisas i tabell där informanternas sammanlagda bedömning eller skattning av påståendena redovisas. Informanternas svar diskuteras och jämförs med den teori som ursprungligen använts för att konstruera frågorna. Metodiska frågor i samband med undersökningen diskuteras också.

    Place, publisher, year, edition, pages
    Jönköping: Jönköping University Press, 2009
    National Category
    Didactics
    Identifiers
    urn:nbn:se:liu:diva-15364 (URN)
    Note

    On the day of the defence date the status of this article was "Manuscript" and the title was "En Delphistudie av initierade brukares och användares uppfattningar om karaktären av integrerad naturvetenskap i senare delen av svenska grundskola"

    Available from: 2008-11-05 Created: 2008-11-05 Last updated: 2017-12-14Bibliographically approved
    2. Integrated and subject-specific Science education: Teachers’ and students’ views
    Open this publication in new window or tab >>Integrated and subject-specific Science education: Teachers’ and students’ views
    (English)Manuscript (Other academic)
    Abstract [en]

    This study concerns the views of teachers’ and students’ regarding Science education. The teachers and students are all from four schools in the same small town in Sweden. The teachers’ views of Science lessons focused on how to plan lessons and organise content. The students’ views focused on three questions concerning the integration of science. The study is based on several data collections: interviews with and observations of teachers, a school survey and student questionnaires. The teacher interviews were analysed with regard to integrated and subject-specific Science education and the students’ questionnaires were analysed with statistical methods. The four schools in this study may be categorised as two integrated schools, one subject-specific and one mixed school. The students’ views of subjectspecific and integrated Science did not completely coincide with the teachers’ views. Teachers and students agreed on that they did integrated education in only one out of the four schools.

    Keywords
    Science education, teachers’ and students’ views, integrated and subject specific Science
    National Category
    Pedagogy
    Identifiers
    urn:nbn:se:liu:diva-15475 (URN)
    Available from: 2008-11-11 Created: 2008-11-11 Last updated: 2010-01-14Bibliographically approved
    3. Using hierarchical linear models to test differences in Swedish results from OECD's PISA 2003: Integrated and Subject-specific science education
    Open this publication in new window or tab >>Using hierarchical linear models to test differences in Swedish results from OECD's PISA 2003: Integrated and Subject-specific science education
    2007 (English)In: NorDiNa: Nordic Studies in Science Education, ISSN 1504-4556, E-ISSN 1894-1257, no 2, p. 121-131Article in journal (Refereed) Published
    Abstract [en]

    The possible effects of different organisations of the science curriculum in schools participating in PISA 2003 are tested with a hierarchical linear model (HLM) of two levels. The analysis is based on science results. Swedish schools are free to choose how they organise the science curriculum. They may choose to work subject-specifically (with Biology, Chemistry and Physics), integrated (with Science) or to mix these two. In this study, all three ways of organising science classes in compulsory school are present to some degree. None of the different ways of organising science education displayed statistically significant better student results in scientific literacy as measured in PISA 2003. The HLM model used variables of gender, country of birth, home language, preschool attendance, an economic, social and cultural index as well as the teaching organisation.

    Keywords
    science education
    National Category
    Pedagogy
    Identifiers
    urn:nbn:se:miun:diva-5130 (URN)5274 (Local ID)5274 (Archive number)5274 (OAI)
    Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2017-12-12Bibliographically approved
    4. Differences between students in Swedish compulsory schools with integrated andsubject-specific Science education in PISA 2006
    Open this publication in new window or tab >>Differences between students in Swedish compulsory schools with integrated andsubject-specific Science education in PISA 2006
    (English)Manuscript (Other academic)
    Abstract [en]

    This study is a comparison between three groups of teaching organisations in Sweden that work either with integrated Science, subject-specific Science or a mixed form of the two. Comparison is made between the students’ total Science scores in the PISA 2006 study and the three scores in student competency regarding Knowledge in Science and Knowledge about Science. This comparison is made both at the individual and school level. There are differences between students with integrated Science education and students with subjectspecific Science. These differences are found both in the total scores and in some of the subscores. An even more striking difference is found between boys and girls in the different groups. There are big differences in test scores for girls with integrated Science as compared to girls with subject-specific Science; this difference is almost nonexistent for boys. Some caution must be shown in drawing conclusions from this finding, however, since girls’ and boys’ groups differ in mean ESCS, and there are differences in the percentage of students who speak another language at home than Swedish. Some plausible explanations for the differences are discussed based on inferences from other studies.

    National Category
    Didactics
    Identifiers
    urn:nbn:se:liu:diva-15365 (URN)
    Available from: 2008-11-05 Created: 2008-11-05 Last updated: 2010-01-14Bibliographically approved
  • 101984.
    Åström, Maria
    et al.
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Karl-Göran, Karlsson
    Department of Engineering, Physics and Mathematics, Mid Sweden University.
    Using hierarchical linear models to test differences in Swedish results from OECD’sPISA 2003: Integrated and subject-specific science education2007In: NorDiNa: Nordic Studies in Science Education, ISSN 1504-4556, E-ISSN 1894-1257, Vol. 3, no 2, p. 121-131Article in journal (Refereed)
    Abstract [en]

    The possible effects of different organisations of the science curriculum in schools participating in PISA 2003 are tested with a hierarchical linear model (HLM) of two levels. The analysis is based on science results. Swedish schools are free to choose how they organise the science curriculum. They may choose to work subject-specifically (with Biology, Chemistry and Physics), integrated (with Science) or to mix these two. In this study, all three ways of organising science classes in compulsory school are present to some degree. None of the different ways of organising science education displayed statistically significant better student results in scientific literacy as measured in PISA 2003. The HLM model used variables of gender, country of birth, home language, preschool attendance, an economic, social and cultural index as well as the teaching organisation.

  • 101985.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Functional brain atlas2014Conference paper (Other academic)
  • 101986.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Modelling, Simulaltion, and Visualization of Deep Brain Stimulation2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Deep brain stimulation (DBS) is an effective surgical treatment for neurological diseases such as essential tremor, Parkinsonʹs disease (PD) and dystonia. DBS has so far been used in more than 70 000 patients with movement disorders, and is currently in trial for intractable Gilles de la Tourette’s syndrome, obsessive compulsive disorders, depression, and epilepsy. DBS electrodes are implanted with stereotactic neurosurgical techniques in the deep regions of the brain. Chronic electrical stimulation is delivered to the electrodes from battery-operated pulse generators that are implanted below the clavicle.

    The clinical benefit of DBS is largely dependent on the spatial distribution of the electric field in relation to brain anatomy. To maximize therapeutic benefits while avoiding unwanted side-effects, knowledge of the distribution of the electric field in relation anatomy is essential. Due to difficulties in measuring electric fields in vivo, computerized analysis with finite element models have emerged as an alternative.

    The aim of the thesis was to investigate technical and clinical aspects of DBS by means of finite element models, simulations, and visualizations of the electric field and tissue anatomy. More specifically the effects of dilated perivascular spaces filled with cerebrospinal fluid on the electrical field generated by DBS was evaluated. A method for patient-specific finite element modelling and simulation of DBS was developed and used to investigate the anatomical distribution of the electric field in relation to clinical effects and side effects. Patient-specific models were later used to investigate the electric field in relation to effects on speech and movement during DBS in patients with PD (n=10). Patient-specific models and simulations were also used to evaluate the influence of heterogeneous isotropic and heterogeneous anisotropic tissue on the electric field during DBS. In addition, methods were developed for visualization of atlas-based and patient-specific anatomy in 3D for interpretation of anatomy, visualization of neural activation with the activating function, and visualization of tissue micro structure. 3D visualization of anatomy was used to assess electrode contact locations in relation to stimulation-induced side-effects (n=331) during DBS for patients with essential tremor (n=28). The modelling, simulation, and visualization of DBS provided detailed information about the distribution of the electric field and its connection to clinical effects and side-effects of stimulation. In conclusion, the results of this thesis provided insights that may help to improve DBS as a treatment for movement disorders as well as for other neurological diseases in the future.

    List of papers
    1. The effect of cystic cavities on deep brain stimulation in the basal ganglia: A simulation-based study
    Open this publication in new window or tab >>The effect of cystic cavities on deep brain stimulation in the basal ganglia: A simulation-based study
    Show others...
    2006 (English)In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 3, no 2, p. 132-138Article in journal (Refereed) Published
    Abstract [en]

    Although the therapeutic effect of deep brain stimulation (DBS) is well recognized, a fundamental understanding of the mechanisms responsible is still not known. In this study finite element method (FEM) modelling and simulation was used in order to study relative changes of the electrical field extension surrounding a monopolar DBS electrode positioned in grey matter. Due to the frequently appearing cystic cavities in the DBS-target globus pallidus internus, a nucleus of grey matter with and without a cerebrospinal fluid filled cystic cavity was modelled. The position, size and shape of the cyst were altered in relation to the electrode. The simulations demonstrated an electrical field around the active element with decreasing values in the radial direction. A stepwise change was present at the edge between grey and white matters. The cyst increased the radial extension and changed the shape of the electrical field substantially. The position, size and shape of the cyst were the main influencing factors. We suggest that cystic cavities in the DBS-target may result in closely related unexpected structures or neural fibre bundles being stimulated and could be one of the reasons for suboptimal clinical effects or stimulation-induced side effects. © 2006 IOP Publishing Ltd.

    Place, publisher, year, edition, pages
    Institute of Physics Publishing (IOPP), 2006
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-34125 (URN)10.1088/1741-2560/3/2/007 (DOI)000239673500007 ()16705269 (PubMedID)2-s2.0-33744911364 (Scopus ID)20869 (Local ID)20869 (Archive number)20869 (OAI)
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13Bibliographically approved
    2. Method for patient-specific finite element modeling and simulation of deep brain stimulation
    Open this publication in new window or tab >>Method for patient-specific finite element modeling and simulation of deep brain stimulation
    Show others...
    2009 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 47, no 1, p. 21-28Article in journal (Refereed) Published
    Abstract [en]

    Deep brain stimulation (DBS) is an established treatment for Parkinsons disease. Success of DBS is highly dependent on electrode location and electrical parameter settings. The aim of this study was to develop a general method for setting up patient-specific 3D computer models of DBS, based on magnetic resonance images, and to demonstrate the use of such models for assessing the position of the electrode contacts and the distribution of the electric field in relation to individual patient anatomy. A software tool was developed for creating finite element DBS-models. The electric field generated by DBS was simulated in one patient and the result was visualized with isolevels and glyphs. The result was evaluated and it corresponded well with reported effects and side effects of stimulation. It was demonstrated that patient-specific finite element models and simulations of DBS can be useful for increasing the understanding of the clinical outcome of DBS.

    Place, publisher, year, edition, pages
    Springer, 2009
    Keywords
    Deep brain stimulation, Patient-specific, Simulation, Finite element, Glyph
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-16616 (URN)10.1007/s11517-008-0411-2 (DOI)000262483600004 ()18936999 (PubMedID)2-s2.0-58649107661 (Scopus ID)
    Note

    The original publication is available at www.springerlink.com: Mattias Åström, Ludvic U Zrinzo, Stephen Tisch, Elina Tripoliti, Marwan I Hariz and Karin Wårdell , Method for patient-specific finite element modeling and simulation of deep brain stimulation, 2009, Medical and Biological Engineering and Computing, (47), 1, 21-28. http://dx.doi.org/10.1007/s11517-008-0411-2 Copyright: Springer Science Business Media http://www.springerlink.com/

    Available from: 2009-02-07 Created: 2009-02-06 Last updated: 2017-12-14Bibliographically approved
    3. Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation
    Open this publication in new window or tab >>Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation
    Show others...
    2010 (English)In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 88, no 4, p. 224-233Article in journal (Refereed) Published
    Abstract [en]

    Background/Aims: Deep brain stimulation (DBS) is widely used to treat motor symptoms in patients with advanced Parkinson’s disease. The aim of this study was to investigate the anatomical aspects of the electric field in relation to effects on speech and movement during DBS in the subthalamic nucleus. Methods: Patient-specific finite element models of DBS were developed for simulation of the electric field in 10 patients. In each patient, speech intelligibility and movement were assessed during 2 electrical settings, i.e. 4 V (high) and 2 V (low). The electric field was simulated for each electrical setting. Results: Movement was improved in all patients for both high and low electrical settings. In general, high-amplitude stimulation was more consistent in improving the motor scores than low-amplitude stimulation. In 6 cases, speech intelligibility was impaired during high-amplitude electrical settings. Stimulation of part of the fasciculus cerebellothalamicus from electrodes positioned medial and/or posterior to the center of the subthalamic nucleus was recognized as a possible cause of the stimulation-induced dysarthria. Conclusion: Special attention to stimulation-induced speech impairments should be taken in cases when active electrodes are positioned medial and/or posterior to the center of the subthalamic nucleus.

    Keywords
    Deep brain stimulation, Dysarthria, Speech intelligibility, Parkinson’s disease, Electric field, Fasciculus cerebellothalamicus
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-58057 (URN)10.1159/000314357 (DOI)000280136100004 ()
    Note

    Original Publication: Mattias Åström, Elina Tripoliti, Mawan I. Hariz, Ludvig U. Zrinzo, Irene Martinez-Torres, Patricia Limousin and Karin Wårdell, Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation, 2010, Stereotactic and Functional Neurosurgery, (88), 4, 224-233. http://dx.doi.org/10.1159/000314357 Copyright: S. Karger AG http://www.karger.com/

    Available from: 2010-07-27 Created: 2010-07-27 Last updated: 2017-12-12Bibliographically approved
    4. Influence of heterogeneous and anisotropic tissue conductivity on electric field distribution in deep brain stimulation
    Open this publication in new window or tab >>Influence of heterogeneous and anisotropic tissue conductivity on electric field distribution in deep brain stimulation
    2012 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 50, no 1, p. 23-32Article in journal (Refereed) Published
    Abstract [en]

    The aim was to quantify the influence of heterogeneous isotropic and heterogeneous anisotropic tissue on the spatial distribution of the electric field during deep brain stimulation (DBS). Three finite element tissue models were created of one patient treated with DBS. Tissue conductivity was modelled as I) homogeneous isotropic, II) heterogeneous isotropic based on MRI, and III) heterogeneous anisotropic based on diffusion tensor MRI. Modelled DBS electrodes were positioned in the subthalamic area, the pallidum, and the internal capsule in each tissue model. Electric fields generated during DBS were simulated for each model and target-combination and visualized in 3D with isolevels at 0.20 (inner), and 0.05 V m-1 (outer). F-test and vector analysis was used for statistical evaluation of the distribution of the electric field. Heterogeneous isotropic tissue altered the spatial distribution of the electric field by up to 4% at inner, and up to 10% at outer isolevel. Heterogeneous anisotropic tissue had a larger impact on the distribution of the electric field with an influence of up to 18% and 15% at each isolevel, respectively. The influence of heterogeneous and anisotropic tissue on the electric field may be clinically relevant in anatomic regions that are functionally subdivided and surrounded by multiple fibres of passage.

    Place, publisher, year, edition, pages
    Springer, 2012
    Keywords
    Deep brain stimulation, Diffusion tensor, Finite element, Model, Simulation, Patient-specific
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-70087 (URN)10.1007/s11517-011-0842-z (DOI)000298648400003 ()
    Note

    funding agencies|Swedish Foundation for Strategic Research (SSF)||Swedish Research Council (VR)| 621-2008-3013 |Swedish Governmental Agency for Innovation Systems (VINNOVA)| 311-2006-7661 |

    Available from: 2011-08-18 Created: 2011-08-18 Last updated: 2017-12-08Bibliographically approved
    5. Stimulation-induced side effects in the posterior subthalamic area: distribution, characteristics and visualization
    Open this publication in new window or tab >>Stimulation-induced side effects in the posterior subthalamic area: distribution, characteristics and visualization
    2013 (English)In: Clinical neurology and neurosurgery (Dutch-Flemish ed. Print), ISSN 0303-8467, E-ISSN 1872-6968, Vol. 15, no 1, p. 65-71Article in journal (Refereed) Published
    Abstract [en]

    Objective: The posterior subthalamic area (PSA) is an emerging but relatively unexplored target for DBS treatment of tremor. The aim of the study was to explore the area further by evaluating the spatial distribution and the characteristics of stimulation-induced side effects in this area. Methods: Twenty-eight patients with essential tremor (ET) implanted with 33 DBS electrodes were evaluated concerning stimulation-induced side effects by testing each contact separately one year after surgery. The location of the side effects were plotted on axial slides of the Morel Stereotactic Atlas and a 3-dimensional model of the area for visualization was created. Results: Visualization of the contacts eliciting stimulation-induced side effects demonstrated that identical responses can be elicited from various points in the PSA and its vicinity. The majority of contacts inducing muscular affection and cerebellar symptoms, including dysarthria, could not be attributed to an effect on the internal capsule. Paresthesias, affecting various body parts were elicited throughout the area without a clear somatotopic pattern. Conclusion: Stimulation-induced side effects in the PSA and its vicinity are difficult to attribute to certain anatomical areas as the same response can be induced from various locations, and are thus of limited localizing value.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-70088 (URN)10.1016/j.clineuro.2012.04.015 (DOI)000312576300012 ()
    Available from: 2011-08-18 Created: 2011-08-18 Last updated: 2017-12-08Bibliographically approved
  • 101987.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Neuronmodeling and DBS electric field simulations2014Conference paper (Other academic)
  • 101988.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology. Sapiens Steering Brain Stimulation BV, NL-5656 Eindhoven, Netherlands.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Martens, Hubert
    Sapiens Steering Brain Stimulation B.V., Eindhoven, The Netherlands.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Relationship between Neural Activation and Electric Field Distribution during Deep Brain Stimulation2015In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 62, no 2, p. 664-72Article in journal (Refereed)
    Abstract [en]

    Models and simulations are commonly used to study deep brain stimulation (DBS). Simulated stimulation fields are often defined and visualized by electric field isolevels or volumes of tissue activated (VTA). The aim of the present study was to evaluate the relationship between stimulation field strength as defined by the electric potential V, the electric field E, and the divergence of the electric field ∇(2) V, and neural activation. Axon cable models were developed and coupled to finite-element DBS models in three-dimensional (3-D). Field thresholds ( VT , ET, and ∇(2) VT ) were derived at the location of activation for various stimulation amplitudes (1 to 5 V), pulse widths (30 to 120 μs), and axon diameters (2.0 to 7.5 μm). Results showed that thresholds for VT and ∇(2) VT were highly dependent on the stimulation amplitude while ET were approximately independent of the amplitude for large axons. The activation field strength thresholds presented in this study may be used in future studies to approximate the VTA during model-based investigations of DBS without the need of computational axon models.

  • 101989.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Computational analysis of the electric field during deep brain stimulation (oral, invited)2010Conference paper (Refereed)
  • 101990.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Software for patient-specific modeling and simulation of deep brain stimulation (poster)2011Conference paper (Other academic)
  • 101991.
    Åström, Mattias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Johansson, Johannes
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Hariz, Marwan
    Institute of Neurology London.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    The effect of cystic cavities on deep brain stimulation in the basal ganglia: A simulation-based study2006In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 3, no 2, p. 132-138Article in journal (Refereed)
    Abstract [en]

    Although the therapeutic effect of deep brain stimulation (DBS) is well recognized, a fundamental understanding of the mechanisms responsible is still not known. In this study finite element method (FEM) modelling and simulation was used in order to study relative changes of the electrical field extension surrounding a monopolar DBS electrode positioned in grey matter. Due to the frequently appearing cystic cavities in the DBS-target globus pallidus internus, a nucleus of grey matter with and without a cerebrospinal fluid filled cystic cavity was modelled. The position, size and shape of the cyst were altered in relation to the electrode. The simulations demonstrated an electrical field around the active element with decreasing values in the radial direction. A stepwise change was present at the edge between grey and white matters. The cyst increased the radial extension and changed the shape of the electrical field substantially. The position, size and shape of the cyst were the main influencing factors. We suggest that cystic cavities in the DBS-target may result in closely related unexpected structures or neural fibre bundles being stimulated and could be one of the reasons for suboptimal clinical effects or stimulation-induced side effects. © 2006 IOP Publishing Ltd.

  • 101992.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Johansson, Johannes
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Modeling and simulation of electric fields generated by brain stimulation electrodes: the effect of cystic cavities in the basal ganglia2005In: Proceedings from the International IEEE EMBS Conference on Neural Engineering, IEEE , 2005, p. 198-201Conference paper (Refereed)
    Abstract [en]

    Deep brain stimulation (DBS) is an effective method for managing movement disorders. A small electrode is implanted in the basal ganglia and an electric potential is applied to one or more active elements of the electrode in order to simulate the neurons in the surrounding tissue. The fundamental understanding of the mechanisms responsible for the therapeutic DBS effects is unknown. A method to increase the knowledge is to use computer simulations. In this study the finite element method has been used for investigation of relative changes of the electrical field extension surrounding a monopolar DBS-electrode positioned in gray matter. Due to the frequently appearing cystic cavities in globus pallidus and putamen a nucleus of gray matter with and without a cerebrospinal fluid filled cystic cavity was modeled. The simulations demonstrated an electrical field around the active element with decreasing values in the radial direction. A stepwise change was present at the edge between gray and white matter. The cyst increased the radial extension and changed the shape of the field. This may result in closely related unexpected structures being stimulated and could be one of the reasons of reported postoperative complications.

  • 101993.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Lemair, Jean-Jaques
    Hôpital Gabriel Montpied, Service de Neurochirurgie, Clermont-Ferrand, France.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    The influence of brain tissue heterogeneity and anisotropy on deep brain stimulation in the subhalamic nucleus2009Conference paper (Refereed)
  • 101994.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Lemaire, Jean-Jacques
    Clermont Université, Université d'Auvergne, EA 3295, Equipe de recherche en signal et imagerie médicale, Image- Guided Clinical Neuroscience and Connectomics (IGCNC), BP 10448, F-63000 Clermont-Ferrand, France/CHU Clermont-Ferrand, Service de Neurochirurgie, F-63003 Clermont-Ferrand, France.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Influence of heterogeneous and anisotropic tissue conductivity on electric field distribution in deep brain stimulation2012In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 50, no 1, p. 23-32Article in journal (Refereed)
    Abstract [en]

    The aim was to quantify the influence of heterogeneous isotropic and heterogeneous anisotropic tissue on the spatial distribution of the electric field during deep brain stimulation (DBS). Three finite element tissue models were created of one patient treated with DBS. Tissue conductivity was modelled as I) homogeneous isotropic, II) heterogeneous isotropic based on MRI, and III) heterogeneous anisotropic based on diffusion tensor MRI. Modelled DBS electrodes were positioned in the subthalamic area, the pallidum, and the internal capsule in each tissue model. Electric fields generated during DBS were simulated for each model and target-combination and visualized in 3D with isolevels at 0.20 (inner), and 0.05 V m-1 (outer). F-test and vector analysis was used for statistical evaluation of the distribution of the electric field. Heterogeneous isotropic tissue altered the spatial distribution of the electric field by up to 4% at inner, and up to 10% at outer isolevel. Heterogeneous anisotropic tissue had a larger impact on the distribution of the electric field with an influence of up to 18% and 15% at each isolevel, respectively. The influence of heterogeneous and anisotropic tissue on the electric field may be clinically relevant in anatomic regions that are functionally subdivided and surrounded by multiple fibres of passage.

  • 101995.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Medtronic, Sweden; Medtronic, Netherlands.
    Samuelsson, Jennifer
    Umea Univ, Sweden.
    Roothans, Jonas
    Medtronic, Sweden; Medtronic, Netherlands.
    Fytagoridis, Anders
    Umea Univ, Sweden; Karolinska Inst, Sweden.
    Ryzhkov, Maxim
    Medtronic, Sweden; Medtronic, Netherlands.
    Nijlunsing, Rutger
    Medtronic, Sweden; Medtronic, Netherlands.
    Blomstedt, Patric
    Umea Univ, Sweden.
    Prediction of Electrode Contacts for Clinically Effective Deep Brain Stimulation in Essential Tremor2018In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 96, no 5, p. 281-288Article in journal (Refereed)
    Abstract [en]

    Background/Aim: Deep brain stimulation (DBS) is an established neurosurgical treatment that can be used to alleviate symptoms in essential tremor (ET) and other movement disorders. The aim was to develop a method and software tool for the prediction of effective DBS electrode contacts based on probabilistic stimulation maps (PSMs) in patients with ET treated with caudal zona incerta (cZi) DBS. Methods: A total of 33 patients (37 leads) treated with DBS were evaluated with the Essential Tremor Rating Scale (ETRS) 12 months after surgery. In addition, hand tremor and hand function (ETRS items 5/6 and 11-14) were evaluated for every contact during stimulation with best possible outcome without inducing side effects. Prediction of effective DBS electrode contacts was carried out in a retrospective leave-one-out manner based on PSMs, simulated stimulation fields, and a scoring function. Electrode contacts were ranked according to their likelihood of being included in the clinical setting. Ranked electrode contacts were compared to actual clinical settings. Results: Predictions made by the software tool showed that electrode contacts with rank 1 matched the clinically used contacts in 60% of the cases. Contacts with a rank of 1-2 and 1-3 matched the clinical contacts in 83 and 94% of the cases, respectively. Mean improvement of hand tremor and hand function was 79 +/- 21% and 77 +/- 22% for the clinically used and the predicted electrode contacts, respectively. Conclusions: Effective electrode contacts can be predicted based on PSMs in patients treated with cZi DBS for ET. Predictions may in the future be used to reduce the number of clinical assessments that are carried out before a satisfying stimulation setting is defined. (C) 2018 S. Karger AG, Basel

  • 101996.
    Åström, Mattias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Tisch, Stephen
    Institute of Neurology University College, London, UK.
    Zrinzo, Ludvic U.
    Institute of Neurology University College, London, UK.
    Tripoliti, Elina
    University of Neurology University College, London, UK.
    Hariz, Marwan I.
    Department of Neurosurgery University Hospital, Umeå, Sweden.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    A model-Based analysis of deep brain stimulation2007Conference paper (Other academic)
    Abstract [en]

      

  • 101997.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Tripoliti, E
    n/a.
    Hariz, M I
    n/a.
    Zrinzo, L U
    n/a.
    Martinez-Torre, I
    n/a.
    Limousin, P
    n/a.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Swedish Movement Disorder Society, Umeå 15-16 october, 20092009In: The electric field during DBS, 2009Conference paper (Other academic)
  • 101998.
    Åström, Mattias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Tripoliti, E.
    Institute of Neurology University College London.
    Zrinzo, U.
    Institute of Neurology University College London.
    Marinez-Torres, I.
    Institute of Neurology University College London.
    Limousin, P.
    Institute of Neurology University College London.
    Hariz, M. I.
    Institute of Neurology University College London.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Voltage steering to control deep brain stimulation-induced speech deficits2008In: XVIII Congress of the European Society for Stereotactic and Functional Neurosurgery,2008, 2008Conference paper (Other academic)
  • 101999.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Tripoliti, Elina
    University College, London.
    Hariz, Mawan I.
    University Hospital, Umeå .
    Zrinzo, Ludvig U.
    University College, London.
    Martinez-Torres, Irene
    University College, London.
    Limousin, Patricia
    University College, London.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation2010In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 88, no 4, p. 224-233Article in journal (Refereed)
    Abstract [en]

    Background/Aims: Deep brain stimulation (DBS) is widely used to treat motor symptoms in patients with advanced Parkinson’s disease. The aim of this study was to investigate the anatomical aspects of the electric field in relation to effects on speech and movement during DBS in the subthalamic nucleus. Methods: Patient-specific finite element models of DBS were developed for simulation of the electric field in 10 patients. In each patient, speech intelligibility and movement were assessed during 2 electrical settings, i.e. 4 V (high) and 2 V (low). The electric field was simulated for each electrical setting. Results: Movement was improved in all patients for both high and low electrical settings. In general, high-amplitude stimulation was more consistent in improving the motor scores than low-amplitude stimulation. In 6 cases, speech intelligibility was impaired during high-amplitude electrical settings. Stimulation of part of the fasciculus cerebellothalamicus from electrodes positioned medial and/or posterior to the center of the subthalamic nucleus was recognized as a possible cause of the stimulation-induced dysarthria. Conclusion: Special attention to stimulation-induced speech impairments should be taken in cases when active electrodes are positioned medial and/or posterior to the center of the subthalamic nucleus.

  • 102000.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Tripoliti, Elina
    Institute of Neurology, Queen Square, University College London, UK.
    Martinez-Torres, Irene
    Institute of Neurology, Queen Square, University College London, UK.
    Zrinzo, Ludvic U.
    Institute of Neurology, Queen Square, University College London, UK.
    Limousin, Patricia
    Institute of Neurology, Queen Square, University College London, UK.
    Hariz, Marwan I.
    Institute of Neurology, Queen Square, University College London, UK; Dept of Neurosurgery, University Hospital, Umeå, Sweden.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Patient-specific models and simulations of deep brain stimulation for postoperative follow-up2009In: World Congress on Medical Physics and Biomedical Engineering / [ed] Olaf Dössel and Wolfgang C. Schlegel, Springer , 2009, p. 331-334Conference paper (Refereed)
    Abstract [en]

    Deep brain stimulation (DBS) is an established treatment for Parkinson’s disease (PD). The success of DBS is highly dependent on electrode location and electrical parameter settings. In this study patient-specific computer models of DBS were used for postoperative follow-up in three PD patients who suffered from stimulation induced hypomania, dysarthria, and uncontrollable laughter respectively. The overall aim of the study was to relate the anatomical aspect of the electric field to the effects and side effects of stimulation. The simulations showed the anatomical distribution of the electric field for all the patients and the results were in agreement with previous reports regarding these side effects of stimulation. It was demonstrated that patient-specific models and simulations of DBS may be useful for postoperative follow-up of DBS.

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