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  • 1.
    Chau, Chieu Vinh
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    3D-modeling of Norrköping2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The interest for a detailed and high solution city model has been large within the project” Optical signature analysis” at the department for Sensor Technology in FOI, Linköping. Thus, a textured 3D-model over Norrköping is needed, which later can be imported into simulation software to study optical signature in urban environment.

    The aim with this thesis work is to be able to use the result as a multi-used 3D-model within applications of the Swedish defence force for future usage. It is important to have a realistic representation of the environment so that the exercises can be planned and analyzed at the current position.

    For the final result to be as good as possible, the thesis work has been concentrated and limited into a smaller area, i.e. the quarter of Svärdet at Nya torget. Thereafter the thesis work has been divided into different stages: photographing, laser measurement, photomontage, modeling and texturing.

    One of the most important and extensive stages is to make the high solution and detailed texture pictures with photomontage. These pictures are first created with photographing and then be performed into panorama pictures. Further, the thesis work has been performed with suitable software, such as 3ds Max and Photoshop CS.

    The finished 3D-model will be supplied as a 3ds-file and max-file, where the textured pictures from the model have been moved into a folder to facilitate future works, for example in classification of texture-pictures.

  • 2.
    Cahill, N
    et al.
    Uppsala University, Sweden.
    Bergh, Ann-Charlotte
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Kanduri, M
    Uppsala University, Sweden.
    Göransson-Kultima, H
    Uppsala University, Sweden.
    Mansouri, L
    Uppsala University, Sweden.
    Isaksson, A
    Sahlgrenska University Hospital, Sweden.
    Ryan, F
    Institute of Technology, Dublin, Ireland.
    Smedby, K E
    Karolinska Institutet, Stockholm, Sweden.
    Juliusson, G
    Institute of Technology, Dublin, Ireland.
    Sundström, C
    Uppsala University, Sweden.
    Rosén, Anders
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Rosenquist, R
    Uppsala University, Sweden.
    450K-array analysis of chronic lymphocytic leukemia cells reveals global DNA methylation to be relatively stable over time and similar in resting and proliferative compartments2013In: Leukemia, ISSN 0887-6924, E-ISSN 1476-5551, Vol. 27, no 1, 150-158 p.Article in journal (Refereed)
    Abstract [en]

    In chronic lymphocytic leukemia (CLL), the microenvironment influences gene expression patterns; however, knowledge is limited regarding the extent to which methylation changes with time and exposure to specific microenvironments. Using high-resolution 450K-arrays, we provide the most comprehensive DNA methylation study of CLL to date, analysing paired diagnostic/follow-up samples from IGHV-mutated/untreated and IGHV-unmutated/treated patients (n=36) and patient-matched peripheral blood and lymph node samples (n=20). On an unprecedented scale, we revealed 2239 differentially methylated CpG sites between IGHV-mutated and unmutated patients, with the majority of sites positioned outside annotated CpG islands. Intriguingly, CLL prognostic genes (e.g. CLLU1, LPL, ZAP70, NOTCH1), epigenetic regulator (e.g. HDAC9, HDAC4, DNMT3B), B-cell signaling (e.g. IBTK) and numerous TGF-ß and NF-κB/TNF pathway genes were alternatively methylated between subgroups. Contrary, DNA methylation over time was deemed rather stable with few recurrent changes noted within subgroups. Although a larger number of non-recurrent changes were identified among IGHV-unmutated relative to mutated cases over time, these equated to a low global change. Similarly, few changes were identified between compartment cases. Altogether, we reveal CLL subgroups to display unique methylation profiles and unveil methylation as relatively stable over time and similar within different CLL compartments, implying aberrant methylation as an early leukemogenic event.Leukemia accepted article preview online, 27 August 2012; doi:10.1038/leu.2012.245.

  • 3.
    Dyverfeldt, Petter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bissell, Malenka
    University of Oxford, England.
    Barker, Alex J.
    Northwestern University, IL 60611 USA.
    Bolger, Ann F
    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. University of Calif San Francisco, CA USA.
    Carlhäll, Carljohan
    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. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ebbers, Tino
    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. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Francios, Christopher J.
    University of Wisconsin, WI 53706 USA.
    Frydrychowicz, Alex
    University Hospital Schleswig Holstein, Germany.
    Geiger, Julia
    University of Childrens Hospital Zurich, Switzerland.
    Giese, Daniel
    University Hospital Cologne, Germany.
    Hope, Michael D.
    University of Calif San Francisco, CA USA.
    Kilner, Philip J.
    University of London Imperial Coll Science Technology and Med, England.
    Kozerke, Sebastian
    University of Zurich, Switzerland; ETH, Switzerland.
    Myerson, Saul
    University of Oxford, England.
    Neubauer, Stefan
    University of Oxford, England.
    Wieben, Oliver
    University of Wisconsin, WI 53706 USA.
    Markl, Michael
    Northwestern University, IL 60611 USA; Northwestern University, IL 60611 USA.
    4D flow cardiovascular magnetic resonance consensus statement2015In: Journal of Cardiovascular Magnetic Resonance, ISSN 1097-6647, E-ISSN 1532-429X, Vol. 17, no 72Article, review/survey (Refereed)
    Abstract [en]

    Pulsatile blood flow through the cavities of the heart and great vessels is time-varying and multidirectional. Access to all regions, phases and directions of cardiovascular flows has formerly been limited. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has enabled more comprehensive access to such flows, with typical spatial resolution of 1.5x1.5x1.5 - 3x3x3 mm(3), typical temporal resolution of 30-40 ms, and acquisition times in the order of 5 to 25 min. This consensus paper is the work of physicists, physicians and biomedical engineers, active in the development and implementation of 4D Flow CMR, who have repeatedly met to share experience and ideas. The paper aims to assist understanding of acquisition and analysis methods, and their potential clinical applications with a focus on the heart and greater vessels. We describe that 4D Flow CMR can be clinically advantageous because placement of a single acquisition volume is straightforward and enables flow through any plane across it to be calculated retrospectively and with good accuracy. We also specify research and development goals that have yet to be satisfactorily achieved. Derived flow parameters, generally needing further development or validation for clinical use, include measurements of wall shear stress, pressure difference, turbulent kinetic energy, and intracardiac flow components. The dependence of measurement accuracy on acquisition parameters is considered, as are the uses of different visualization strategies for appropriate representation of time-varying multidirectional flow fields. Finally, we offer suggestions for more consistent, user-friendly implementation of 4D Flow CMR acquisition and data handling with a view to multicenter studies and more widespread adoption of the approach in routine clinical investigations.

  • 4.
    Almer, Sven
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology . Linköping University, Faculty of Health Sciences.
    Hjortswang, Henrik
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology . Linköping University, Faculty of Health Sciences.
    Hindorf , U
    Lund University.
    6-Thioguanine therapy in Crohns disease-Observational data in Swedish patients2009In: Digestive and Liver Disease, ISSN 1590-8658, Vol. 41, no 3, 194-200 p.Article in journal (Refereed)
    Abstract [en]

    Background and aims: Adverse events (AE) leading to discontinuation or dose-reduction of thiopurine therapy (TP) occur in 9-28% of patients with inflammatory bowel disease. 6-Thioguanine (6-TG) has been proposed as an alternative treatment in patients intolerant for azathioprine (AZA), but some concerns have been raised about drug safety.

    Methods: We evaluated in a prospective manner the tolerance and efficacy of 6-TG in 23 Crohns disease (CD) patients (13 men, median age 41 (19-65) years) with prior intolerance (n = 18) or resistance (It = 5) to AZA and/or 6-mercaptopurine (6-MP). In addition, eight patients had tried mycophenolate mofetil. Seventeen patients (74%) had undergone intestinal resection, often several times.

    Results: Patients were treated with a median daily dose of 40 mg 6-TG (range 20-60) for 259 (15-2272) days. Seven of 13 patients (54%) with active disease went into remission after 8 (4-26) weeks. Sixteen patients (70%) experienced AE that lead to discontinuation (n=10) after 85 (15-451) days or dose reduction (n=6) after 78 (10-853) days. Ten of 18 patients (56%) with prior TP-intolerance discontinued 6-TG treatment due to AE compared to none of five patients with TP-resistance (p=0.046). Of 13 patients that tolerated 6-TG, eight discontinued the drug due to therapeutic failure (n=5) or safety concerns (n=3). Eight patients (35%) continued treatment beyond 12 months. There was no significant difference in maximum thioguanine nucleotide levels between patients with AE leading to discontinuation/dose reduction and patients without AE, 652 (99-2488) vs. 551 (392-1574) pmol/8 x 10(8) RBC; p=0.80.

    Conclusions: In this cohort of CD patients with severe disease failing traditional thiopurine treatment, a small fraction (22%) had long-term benefit of 6-TG-treatment. 6-TG therapy seems to offer a limited therapeutic gain for patients intolerant to both AZA and 6-MP and other treatment options should be considered.

  • 5.
    Saifullah, Mohammad
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Balkenius, Christian
    Lund University Cognitive Science, Sweden.
    Jönsson, Arne
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Arts and Sciences.
    A biologically based model for recognition of 2-D occluded patterns2014In: Cognitive Processing, ISSN 1612-4782, Vol. 15, no 1, 13-28 p.Article in journal (Refereed)
    Abstract [en]

    In this work, we present a biologically inspired model for recognition of occluded patterns. The general architecture of the model is based on the two visual information processing pathways of the human visual system, i.e. the ventral and the dorsal pathways. The proposed hierarchically structured model consists of three parallel processing channels. The main channel learns invariant representations of the input patterns and is responsible for pattern recognition task. But, it is limited to process one pattern at a time. The direct channel represents the biologically based direct connection from the lower to the higher processing level in the human visual cortex. It computes rapid top-down pattern-specific cues to modulate processing in the other two channels. The spatial channel mimics the dorsal pathway of the visual cortex. It generates a combined saliency map of the input patterns and, later, segments the part of the map representing the occluded pattern. This segmentation process is based on our hypothesis that the dorsal pathway, in addition to encoding spatial properties, encodes the shape representations of the patterns as well. The lateral interaction between the main and the spatial channels at appropriate processing levels and top-down, pattern-specific modulation of the these two channels by the direct channel strengthen the locations and features representing the occluded pattern. Consequently, occluded patterns become focus of attention in the ventral channel and also the pattern selected for further processing along this channel for final recognition.

  • 6.
    Eklund, Anders
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Ohlsson, Henrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Ynnerman, Anders
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    A Brain Computer Interface for Communication Using Real-Time fMRI2010In: Proceedings of the 20th International Conference on Pattern Recognition, Los Alamitos, CA, USA: IEEE Computer Society, 2010, 3665-3669 p.Conference paper (Refereed)
    Abstract [en]

    We present the first step towards a brain computer interface (BCI) for communication using real-time functional magnetic resonance imaging (fMRI). The subject in the MR scanner sees a virtual keyboard and steers a cursor to select different letters that can be combined to create words. The cursor is moved to the left by activating the left hand, to the right by activating the right hand, down by activating the left toes and up by activating the right toes. To select a letter, the subject simply rests for a number of seconds. We can thus communicate with the subject in the scanner by for example showing questions that the subject can answer. Similar BCI for communication have been made with electroencephalography (EEG). The subject then focuses on a letter while different rows and columns of the virtual keyboard are flashing and the system tries to detect if the correct letter is flashing or not. In our setup we instead classify the brain activity. Our system is neither limited to a communication interface, but can be used for any interface where five degrees of freedom is necessary.

  • 7.
    Ulfendahl, Mats
    et al.
    Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
    Hu, Zhengqing
    Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
    Olivius, Petri
    Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
    Duan, Maoli
    Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
    Wei, Dongguang
    Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
    A cell therapy approach to substitute neural elements in the inner ear2007In: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 92, no 1-2, 75-79 p.Article in journal (Refereed)
    Abstract [en]

    Three different donor tissues were tested for their capacity to survive, integrate and differentiate in the adult inner ear. Surviving embryonic dorsal root ganglion cells were found within the spiral ganglion neuron region and along the auditory nerve fibers. In the presence of exogenous nerve growth factor (NGF), the dorsal root ganglion cells formed extensive growth of neurites that seemed to contact the host neurons. Adult neural stem cells survived relative poorly in the inner car whereas embryonic stem cells showed a somewhat greater capacity for survival and integration. Overall, the survival rate of implanted tissue was quite low in the cochlea. It is concluded that an inner ear cell therapy approach based on the implantation of exogenous cells will require that important survival factors are identified and supplied. In addition, it is possible that the physical properties of the cochlea, e.g., fluid-filled compartments and very limited space for cell proliferation, are unfavorable, at least in the normal cochlea.

  • 8.
    Lindqvist, Maria
    et al.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Isaksson, Barbro
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Microbiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Microbiology.
    Samuelsson, Annika
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Nilsson, Lennart
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Microbiology . Linköping University, Faculty of Health Sciences.
    Hällgren, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Infectious Diseases in Östergötland.
    A clonal outbreak of methicillin-susceptible Staphylococcus aureus with concomitant resistance to erythromycin, clindamycin and tobramycin in a Swedish county2009In: SCANDINAVIAN JOURNAL OF INFECTIOUS DISEASES, ISSN 0036-5548, Vol. 41, no 5, 324-333 p.Article in journal (Refereed)
    Abstract [en]

    In contrast to methicillin-resistant Staphylococcus aureus (MRSA), studies on clonal distribution of methicillin-susceptible S. aureus (MSSA) are scarce. Since 2004, an increasing incidence of concomitant resistance to erythromycin, clindamycin and tobramycin (ECT) among MSSA has been detected in Ostergotland County, Sweden. The objectives of this study were to investigate the genetic relatedness among these isolates with 2 genotyping methods, pulsed-field gel electrophoresis (PFGE), and sequence-based typing of the polymorphic region X of the staphylococcal protein A gene (spa typing), and to determine the incidence of the Panton-Valentine leukocidin (PVL) gene. When genotyping 54 ECT-resistant MSSA isolates from 49 patients (1 isolate per patient per y), 91% were shown to be part of a clonal outbreak with both methods used (spa type t002). The clonal outbreak was concentrated in 8 hospital departments and 2 primary care centres, all located in the city of Linkoping. All isolates were negative for the PVL gene. In conclusion, this study demonstrates an ongoing clonal outbreak of PVL-negative ECT-resistant MSSA. This stresses the need to continuously maintain basic hygiene rules, since nosocomial transmission of pathogens is not limited to known resistant bacteria such as MRSA.

  • 9.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    A Close-Up Investigation of Halftone Color Prints2008In: TAGA 2008 proceedings, Sewickley, PA, USA: TAGA - Technical Association of the Graphic Arts , 2008, 347-363 p.Conference paper (Other academic)
    Abstract [en]

    Modeling the color reproduction of halftone prints is difficult, because of light scattering, causing optical dot gain. Most available models are limited to macroscopic color measurements, averaging the reflectance over an area that is large relative the dot size. The aim of this study is to go beyond the macroscopic approach and study optical dot gain on a micro-scale level, using colorimetric images of printed halftones. An experimental imaging system, combining the accuracy of color measurement instruments with a high spatial resolution, opens up possibilities to better study the color reproduction in halftone color prints. The main focus is to study how the reflectance values of the printed dots and the paper between the dots, Ri(Fi) and Rp(Fi), vary with the dot area fraction. Micro-scale images, i.e. when the resolution of the images is high in relation to the resolution of the halftone, allow for measurements of the individual halftone dots, as well as the paper between them. To capture the characteristics of large populations of halftone dots, histograms are computed. From the histogram data it is possible to derive the mean reflectance, R, the reflectance for the dots, Ri(Fi), and the paper between the dots, Rp(Fi). The true dot area coverage, including the physical dot gain, is computed using histogram data, as well as using line scans in the micro-scale images. A previously proposed extension of the Murray-Davies equation, incorporating Ri(Fi) and Rp(Fi), is evaluated. The model is further extended to handle color prints, predicting tristimulus values, by using 3D histograms in CIEXYZ color space. To reduce the complexity, projection from XYZ coordinates into one dimensional color distributions are used. The prediction errors of the model were found to be equivalent, or better, to that of the Yule-Nielsen model using an optimal n-factor. However, unlike Yule-Nielsen, the extended Murray-Davies model preserves the linear additivity of reflectance, thus providing a better physical description of optical dot gain in halftone color prints.

  • 10.
    Doillon, CJ
    et al.
    CHUL Research Center, Laval University, Quebec City, Quebec, Canada.
    Watsky, MA
    Department of Physiology, University of Tennessee, Health Science Center, Memphis, TN, USA.
    Hakim, M
    University of Ottawa Eye Institute, University of Ottawa, Ottawa, Canada.
    Wang, J
    Department of Physiology, University of Tennessee, Health Science Center, Memphis, TN, USA.
    Munger, R
    University of Ottawa Eye Institute, University of Ottawa, Ottawa, Canada.
    Laycock, N
    University of Ottawa Eye Institute, University of Ottawa, Ottawa, Canada.
    Osborne, R
    The Procter and Gamble Company, Miami Valley Laboratories, Cincinnati, OH, USA.
    Griffith, M
    University of Ottawa Eye Institute, University of Ottawa, Ottawa, Canada.
    A collagen-based scaffold for a tissue engineered human cornea: Physical and physiological properties2003In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 26, no 8, 764-773 p.Article in journal (Refereed)
    Abstract [en]

    Stabilized collagen-glycosaminoglycan scaffolds for tissue engineered human corneas were characterized. Hydrated matrices were constructed by blending type I collagen with chondroitin sulphates (CS), with glutaraldehyde crosslinking. A corneal keratocyte cell line was added to the scaffolds with or without corneal epithelial and endothelial cells. Constructs were grown with or without ascorbic acid. Wound-healing was evaluated in chemical-treated constructs. Native, noncrosslinked gels were soft with limited longevity. Crosslinking strengthened the matrix yet permitted cell growth. CS addition increased transparency. Keratocytes grown within the matrix had higher frequencies of K+ channel expression than keratocytes grown on plastic. Ascorbic acid increased uncrosslinked matrix degradation in the presence of keratocytes, while it enhanced keratocyte growth and endogenous collagen synthesis in crosslinked matrices. Wounded constructs showed recovery from exposure to chemical irritants. In conclusion, this study demonstrates that our engineered, stabilized matrix is well-suited to function as an in vitro corneal stroma.

  • 11.
    Hansen, Peo
    Linköping University, REMESO - Institute for Research on Migration, Ethnicity and Society. Linköping University, Department of Thematic Studies. Linköping University, Faculty of Arts and Sciences.
    A Common Market, a Common ‘Problem’: Migration andEuropean Integration Before and After the Launching of the Single Market2005Report (Other (popular science, discussion, etc.))
    Abstract [en]

    Since the ratification of the Amsterdam Treaty in 1999 the European Union is emerging as a key actor within migration policy. But in order to understand the current development it is important to have a clear picture of the EU’s historical trajectory in the field of migration. In this paper the discussion thus focus esexclusively on the pre-Amsterdam era. It sets out with a brief historical overview of the early decades of European integration and accounts for labour migration’s crucial function in the founding logic of the EEC. While supranational competence over migration policy was very limited during this period, the discussion shows that the way in which competence was allocated between supranational and national levels would be highly consequential for the future development. Following this, the major part of the paper is devoted to an examination of the Community’s transformation during the second half of 1980s and the first half of the 1990s. The measures introduced under the banner of the Single Market, particularly those pertaining to the free movement of persons, instigated a development whereby immigration and asylum would be progressively treated as ‘common’ Community matters. Equally important, the paper shows that Community activity in the area of migration also addressed a range of other matters, many of which went beyond the issue of people moving across external and internal borders. From then on, Brussels began to address the situation of ethnic minorities of migrant background, thus bringing the growing problems of ethnic exclusion and racism on to the EU agenda. On the whole, it was the question of how to better ‘integrate’ ‘legal immigrants’ and ethnic minorities into Community societies that received the most attention. In this fashion, the present paper examines the EU’s interventions in the area of immigration and asylum together with its efforts in the realm of migrant ‘integration’. Although very few accounts have undertaken to analyze jointly the EU’s approaches to immigration and migrant ‘integration’, this paper demonstrates that in order to provide a comprehensive analysis of the issues in question, these policy areas need to be approached as inextricably intertwined and as mutually conditioning.

  • 12.
    Hildebrand, Cisilia
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Hörtin, Stina
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A comparative study between Emme and Visum with respect to public transport assignment2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Macroscopic traffic simulations are widely used in the world in order to provide assistance in the traffic infrastructure development as well as for the strategic traffic planning. When studying a large traffic network macroscopic traffic simulation can be used to model current and future traffic situations. The two most common software used for traffic simulation in Sweden today are Emme and Visum, developed by INRO respective PTV.

    The aim of the thesis is to perform a comparison between the software Emme and Visum with respect to the assignment of public transport, in other words how passengers choose their routes on the existing public transport lines. However, in order to make a complete software comparison the run-time, analysis capabilities, multi-modality, capacity to model various behavioural phenomena like crowding, fares etc. this will not be done in this comparison. It is of interest to study the differences between the two software algorithms and why they might occur because the Swedish Transport Administration uses Emme and the Traffic Administration in Stockholm uses Visum when planning public transport. The comparison will include the resulting volumes on transit lines, travel times, flow through specific nodes, number of boarding, auxiliary volumes and number of transits. The goal of this work is to answer the following objective: What are the differences with modelling a public transport network in Emme and in Visum, based on that the passengers only have information about the travel times and the line frequency, and why does the differences occur?

    In order to evaluate how the algorithms work in a larger network, Nacka municipality (in Stockholm) and the new metro route between Nacka Forum and Kungsträdgården have been used. The motivation for choosing this area and case is due to that it is interesting to see what differences could occur between the programs when there is a major change in the traffic network.

    The network of Nacka, and parts of Stockholm City, has been developed from an existing road network of Sweden and then restricted by "cutting out" the area of interest and then removing all public transportation lines outside the selected area. The OD-matrix was also limited and in order not to loose the correct flow of travellers portal zones was used to collect and retain volumes.

    To find out why the differences occur the headway-based algorithms in each software were studied carefully. An example of a small and simple network (consisting of only a start and end node) has been used to demonstrate and show how the algorithms work and why volumes split differently on the existing transit lines in Emme and Visum. The limited network of Nacka shows how the different software may produce different results in a larger public transport network.

    The results show that there are differences between the program algorithms but the significance varies depending on which output is being studied and the size of the network. The Visum algorithm results in more total boardings, i.e. more passengers have an optimal strategy including a transit. The algorithms are very similar in both software programs, since they include more or less parts of the optimal strategy. The parameters used are taken more or less into consideration in Emme and Visum. For example Visum will first of all focus on the shortest total travel time and then consider the other lines with respect to the maximum waiting time. Emme however, first focuses on the shortest travel time and then considers the total travel time for other lines with half the waiting time instead of the maximum wait time. This results in that less transit lines will be attractive in Emme compared to Visum. The thesis concludes that varying the parameters for public transport in each software algorithm one can obtain similar results, which implies that it is most important to choose the best parameter values and not to choose the "best" software when simulating a traffic network.

  • 13.
    Pernestål, Anna
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Wettig, Hannes
    Complex Systems Computations Group, Department of Computer Science, Helsinki Institute for Information Technology, Finland.
    Silander, Tomi
    Complex Systems Computations Group, Department of Computer Science, Helsinki Institute for Information Technology, Finland.
    Nyberg, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Myllymäki, Petri
    Complex Systems Computations Group, Department of Computer Science, Helsinki Institute for Information Technology, Finland.
    A Comparison of Baysian Approaches to Learning in Fault Isolation2009In: Pattern Recognition Letters, ISSN 0167-8655Article in journal (Other academic)
    Abstract [en]

    Fault isolation is the task of localizing faults in a process, given observations from it. To do this, a model describing the relations between faults and observations is needed.

    In this paper we focus on learning such models both from training data and from prior knowledge. There are several challenges in learning for fault isolation.

    The number of data and the available computing resources are often limited. Furthermore, there may be previously unobserved fault patterns.

    To meet these challenges we take on a Bayesian approach.

    We compare five different approaches to learning for fault isolation, and evaluate their performance on a real application, namely the diagnosis of an automotive engine.

  • 14.
    He, Qing
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A Comprehensive Analysis of Optimal Link Scheduling for Emptying a Wireless Network2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless communications have become an important part of modern life. The ubiquitous wireless networks and connectivities generate exponentially increasing data traffic. In view of this, wireless network optimization, which aims at utilizing the limited resource, especially spectrum and energy, as efficiently as possible from a network perspective, is essential for performance improvement and sustainable development of wireless communications.

    In the dissertation, we focus on a fundamental problem of wireless network optimization, link scheduling, as well as its subproblem, link activation. The problem type arises because of the nature of wireless media and hence it is of relevance to a wide range of networks with multiple access. We freshen these classic problems up by novel extensions incorporating new technologies of interference management or with new performance metrics. We also revisit the problems in their classic setup to gain new theoretical results and insights for problem-solving. Throughout the study, we consider the problems with a general setup, such that the insights presented in this dissertation are not constrained to a specific technology or network type. Since link activation and scheduling are key elements of access coordination in wireless communications, the study opens up new approaches that significantly improve network performance, and eventually benefit practical applications.

    The dissertation consists of five research papers. The first paper addresses maximum link activation with cooperative transmission and interference cancellation. Papers II and III investigate the minimum-time link scheduling problem in general and a particular class of networks, respectively. In Paper IV, we consider the scheduling problem of emptying a network in its broad form and provide a general optimality condition. In Paper V, we study the scheduling problem with respect to age of information.

    List of papers
    1. Maximum Link Activation with Cooperative Transmission and Interference Cancellation in Wireless Networks
    Open this publication in new window or tab >>Maximum Link Activation with Cooperative Transmission and Interference Cancellation in Wireless Networks
    2017 (English)In: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 16, no 2, 408-421 p.Article in journal (Other academic) Published
    Abstract [en]

    We address the maximum link activation problem in wireless networks with new features, namely when the transmitters can perform cooperative transmission, and the receivers are able to perform successive interference cancellation. In this new problem setting, which transmitters should transmit and to whom, as well as the optimal cancellation patterns at the receivers, are strongly intertwined. We present contributions along three lines. First, we provide a thorough tractability analysis, proving the NP-hardness as well as identifying tractable cases. Second, for benchmarking purposes, we deploy integer linear programming for achieving global optimum using off-theshelf optimization methods. Third, to overcome the scalability issue of integer programming, we design a sub-optimal but efficient optimization algorithm for the problem in its general form, by embedding maximum-weighted bipartite matching into local search. Numerical results are presented for performance evaluation, to validate the benefit of cooperative transmission and interference cancellation for maximum link activation and to demonstrate the effectiveness of the proposed algorithm.

    Place, publisher, year, edition, pages
    IEEE, 2017
    National Category
    Communication Systems Telecommunications
    Identifiers
    urn:nbn:se:liu:diva-112447 (URN)10.1109/TMC.2016.2546906 (DOI)
    Conference
    2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), September 2-5, Washington DC, DC, USA
    Note

    Funding agencies: Swedish Research Council; EU FP7 Marie Curie [324515, 329313]; National Science Foundation [CCF-0728966, CCF-1420651]; ONR [N000141410107]

    Available from: 2014-11-27 Created: 2014-11-27 Last updated: 2017-03-27Bibliographically approved
    2. Minimum-Time Link Scheduling for Emptying Wireless Systems: Solution Characterization and Algorithmic Framework
    Open this publication in new window or tab >>Minimum-Time Link Scheduling for Emptying Wireless Systems: Solution Characterization and Algorithmic Framework
    2014 (English)In: IEEE Transactions on Information Theory, ISSN 0018-9448, Vol. 60, no 2, 1083-1100 p.Article in journal (Refereed) Published
    Abstract [en]

    We consider a set of transmitter-receiver pairs, or links, that share a wireless medium and address the problem of emptying backlogged queues with given initial size at the transmitters in minimum time. The problem amounts to determining activation subsets of links, and their time durations, to form a minimum-time schedule. Scheduling in wireless networks has been studied under various formulations before. In this paper, we present fundamental insights and solution characterizations that include: 1) showing that the complexity of the problem remains high for any continuous and increasing rate function; 2) formulating and proving sufficient and necessary optimality conditions of two baseline scheduling strategies that correspond to emptying the queues using one-at-a-time or all-at-once strategies; and 3) presenting and proving the tractability of the special case in which the transmission rates are functions only of the cardinality of the link activation sets. These results are independent of physical-layer system specifications and are valid for any form of rate function. We then develop an algorithmic framework for the solution to this problem. The framework encompasses exact as well as sub-optimal, but fast, scheduling algorithms, all under a unified principle design. Through computational experiments, we finally investigate the performance of several specific algorithms from this framework.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2014
    Keyword
    Algorithm; optimality; scheduling; wireless networks
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104836 (URN)10.1109/TIT.2013.2292065 (DOI)000330286100022 ()
    Available from: 2014-02-28 Created: 2014-02-28 Last updated: 2016-09-15
    3. Polynomial Complexity Minimum-Time Scheduling in a Class of Wireless Networks
    Open this publication in new window or tab >>Polynomial Complexity Minimum-Time Scheduling in a Class of Wireless Networks
    2015 (English)In: IEEE Transactions on Control of Network Systems, ISSN 2325-5870, Vol. 3, no 3, 322-331 p.Article in journal (Other academic) Published
    Abstract [en]

    We consider a wireless network with a set of transmitter-receiver pairs, or links, that share a common channel, and address the problem of emptying finite traffic volume from the transmitters in minimum time. This, so called, minimum-time scheduling problem has been proved to be NP-hard in general. In this paper, we study a class of minimum-time scheduling problems in which the link rates have a particular structure. We show that global optimality can be reached in polynomial time and derive optimality conditions. Then we consider a more general case in which we apply the same approach and obtain an approximation as well as lower and upper bounds to the optimal solution. Simulation results confirm and validate our approach.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2015
    Keyword
    algorithm, interference, optimality, scheduling, wireless networks
    National Category
    Communication Systems Telecommunications
    Identifiers
    urn:nbn:se:liu:diva-112446 (URN)10.1109/TCNS.2015.2512678 (DOI)
    Note

    At the time for thesis presentation publication was in status: Manuscript

    Available from: 2014-11-27 Created: 2014-11-27 Last updated: 2016-11-25Bibliographically approved
    4. A general optimality condition of link scheduling for emptying a wireless network
    Open this publication in new window or tab >>A general optimality condition of link scheduling for emptying a wireless network
    2016 (English)In: 2016 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, IEEE , 2016, 1446-1450 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    We consider link scheduling in wireless networks for emptying the queues of the source nodes, and provide a unified mathematical formulation that accommodates all meaningful settings of link transmission rates and network configurations. We prove that, any scheduling problem is equivalent to solving a convex problem defined over the convex hull of the rate region. Based on the fundamental insight, a general optimality condition is derived, that yields a unified treatment of optimal scheduling. Furthermore, we demonstrate the implications and usefulness of the result. Specifically, by applying the theoretical insight to optimality characterization and complexity analysis of scheduling problems, we can both unify and extend previously obtained results.

    Place, publisher, year, edition, pages
    IEEE, 2016
    Series
    IEEE International Symposium on Information Theory. Proceedings, ISSN 2157-8095, E-ISSN 2157-8117
    Keyword
    convex programming;radio links;radio networks;telecommunication scheduling;convex hull;convex problem;general optimality condition;link scheduling;link transmission rates;network configurations;optimal scheduling;source nodes;wireless network;Complexity theory;Information theory;Interference;Optimal scheduling;Processor scheduling;Scheduling;Wireless networks;complexity;optimality;scheduling;wireless networks
    National Category
    Computer Engineering Information Systems Software Engineering
    Identifiers
    urn:nbn:se:liu:diva-131357 (URN)10.1109/ISIT.2016.7541538 (DOI)000390098701102 ()
    Conference
    IEEE International Symposium on Information Theory (ISIT), 2016, Universitat Pompeu Fabra, Barcelona, Spain, July l0-l5, 2016
    Available from: 2016-09-15 Created: 2016-09-15 Last updated: 2017-01-30Bibliographically approved
  • 15.
    Pereira Caldas, Célia
    et al.
    Nursing Faculty, Rio de Janeiro State University, Brazil .
    Berterö, Carina
    Linköping University, Department of Medical and Health Sciences, Nursing Science. Linköping University, Faculty of Health Sciences.
    A Concept Analysis About Temporality and Its Applicability in Nursing Care2012In: Nursing Forum, ISSN 0029-6473, Vol. 47, no 4, 245-252 p.Article in journal (Refereed)
    Abstract [en]

    Topic: Concept analysis of temporality. Purpose: To develop a comprehensive definition of temporality applicable to nursing care. Source: Published literature. Conclusions: Temporality is a central component of our experience of the world. Phenomena such as the passage of time, time cycles, the trajectory of aging, transitions toward something, something being, and life as a limited time are integral to human experience. Temporality could be seen as lived time, and as such it is subjective time as opposed to clock time or objective time. The temporal dimensions of past, present, and future constitute the perspective of a persons temporal world. © 2012 Wiley Periodicals, Inc.

  • 16.
    Gunnarsson, Fredrik
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Blom, Jonas
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    A Concept of Power Control in Cellular Radio Systems1999Report (Other academic)
    Abstract [en]

    Due to the rapid expansion of the cellular radio systems market, and the need for wireless multimedia services, the available resources have to be utilized efficently. A common strategy is to control the transmitter powers of the mobiles and base stations. However, when applying power control to real systems, a number of challenges are prevalent. The performance is limited by time delays, nonlinearities and the availability of measurements and adequate quality measures. In this paper we present a Power Regulator concept, which comprises an Unknown Input Observer, a Quality Mapper and a Power Control Algorithm. The applicability of the concept is exemplified using frequency hopping GSM, and simulations indicate benefits of employing the proposed concept.

  • 17.
    Gunnarsson, Fredrik
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Blom, Jonas
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    A Concept of Power Control in Cellular Radio Systems1999In: Proceedings of the 14th World Congress, 1999Conference paper (Refereed)
    Abstract [en]

    Due to the rapid expansion of the cellular radio systems market, and the need for wireless multimedia services, the available resources have to be utilized efficently. A common strategy is to control the transmitter powers of the mobiles and base stations. However, when applying power control to real systems, a number of challenges are prevalent. The performance is limited by time delays, nonlinearities and the availability of measurements and adequate quality measures. In this paper we present a Power Regulator concept, which comprises an Unknown Input Observer, a Quality Mapper and a Power Control Algorithm. The applicability of the concept is exemplified using frequency hopping GSM, and simulations indicate benefits of employing the proposed concept.

  • 18.
    Arkad, Jenny
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control.
    Andersson, Tomas
    Linköping University, Department of Electrical Engineering, Automatic Control.
    A Control Algorithm for an Ultrasonic Motor2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report is the result of a master thesis work where the goal was to develop acontrol system for a type of ultrasonic motor. The ultrasonic motors use ultrasonicvibrations from a piezoelectric material to produce a rotating motion. They arepowered by two sinusoidal voltages and their control signals generally are thevoltages amplitude, frequency and the phase difference between the two voltages.In this work the focus is on control using only amplitude and frequency. A feedbacksignal was provided by an encoder, giving an angular position. The behavior of themotors were investigated for various sets of control signals. From collected data alinearized static model was derived for the motor speed. This derived model wasused to create a two part control system, with an inner control loop to managethe speed of the motors using a PI controller and an outer control loop to managethe position of the motors. A simple algorithm was used for the position controland the result was a control system able to position the motors with a 0.1 degreeaccuracy. The motors show potential for greater accuracy with a position feedback,but the result in this work is limited by the encoder used in the experiments.

  • 19.
    Dragioti, Elena
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Bernfort, Lars
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Medicine and Health Sciences.
    Levin, Lars-Åke
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Medicine and Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    A cross-sectional study of factors associated with the number of anatomical pain sites in an actual elderly general population: results from the PainS65+cohort2017In: Journal of Pain Research, ISSN 1178-7090, E-ISSN 1178-7090, Vol. 10, 2009-2019 p.Article in journal (Refereed)
    Abstract [en]

    Background: Several studies have illustrated that multisite pain is more frequent than single pain site, and it is associated with an array of negative consequences. However, there is limited knowledge available about the potential factors associated with multisite pain in the elderly general population. Objective: This cross-sectional study examines whether the number of anatomical pain sites (APSs) is related to sociodemographic and health-related factors in older adults including oldestold ages using a new method (APSs) to assess the location of pain on the body. Materials and methods: The sample came from the PainS65+ cohort, which included 6,611 older individuals (mean age = 76.0 years; standard deviation [SD] = 7.4) residing in southeastern Sweden. All the participants completed and returned a postal survey that measured sociodemographic data, total annual income, pain intensity and frequency, general well-being, and quality of life. The number of pain sites (NPS) was marked on a body manikin of 45 sections, and a total of 23 APSs were then calculated. Univariable and multivariable models of regression analysis were performed. Results: Approximately 39% of the respondents had at least two painful sites. The results of the regression analysis showed an independent association between the APSs and the age group of 75-79 years, women, married, high pain intensity and frequency, and low well-being and quality of life, after adjustments for consumption of analgesics and comorbidities. The strongest association was observed for the higher frequency of pain. Conclusion: Our results suggest that APSs are highly prevalent with strong relationships with various sociodemographic and health-related factors and concur well with the notion that multisite pain is a potential indicator of increased pain severity and impaired quality of life in the elderly. Our comprehensive method of calculating the number of sites could be an essential part of the clinical presentation, assessment, and treatment of multisite pain.

  • 20.
    Nordvall, Mathias
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    Samuelsson, Marcus
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    A Design-Oriented Computer Simulation Project for Enabling Reflective Action-Focused Mentoring for Preservice Teachers2013In: Education and poverty: theory, research, policy and praxis, 2013Conference paper (Refereed)
    Abstract [en]

    In Sweden, there is a dearth of authentic learning spaces for pre-service teachers to experience maximized variation of disturbances, provocations, and conflicts that are a natural part of teaching. To provoke such situations for practice with real pupils would be ethically problematic, as it would compromise the integrity, mutual respect, and ethic of caring within the teacher-learner relationship. Its pedagogical scope would also be limited, as real-time classroom management do not allow for adequate reflection. Our paper will explore the use of computer simulations as a tool to use during mentorship for pre-service teachers when learning classroom management. We will therefore focus on understanding the personal leadership experiences that pre-service teachers can develop in computer simulators to become confident leaders in their classroom and how this understanding can be integrated into the design process of such simulators. Perspectives: Earlier empirical studies by (Granström & Einarsson, 1998; removed for blind review) documents problematic situations of disturbances, provocations, and conflicts that affect teachers as well as pupils in Swedish schools. Previous work by (Lewis, 2001) reveals that teachers might resort to punishment when conflicts arise, while (Woolfolk & Weinstein, 2006; Lewis, Romi, Katz & Xing, 2008) problematize the falsely perceived effectiveness of punishment. Our project therefore seeks to empower pre-service teachers by grounding their leadership in personal experiences through classroom computer simulations that allow exploration of alternative strategies for classroom management and continuous reflection on their appropriateness. Modes of Inquiry: A phenomenographical analysis, based on stimulated recall interviews, will focus on pre-service teachers’ verbalized descriptions of classroom management decisions taken within the simulator. This explorative form of reflective action-focused mentoring is contrasted with the standard formats as it seeks to understand the appropriateness of using computer simulations to teach classroom management. Data sources: Data from the project Simulerade Provokationer (eng. Simulated Provocations) generated by pre-service teachers from a Swedish university is utilized. This data includes the choices and verbalized reflections that the pre-service teachers made while exploring the simulation. Results: In the simulation the pre-service teachers are forced to take actions, reflect on choices, and change their decisions in an explorative fashion. The hypothesis being that through active participation and continuous self-reflection pre-service teachers will feel better prepared to be the classroom leaders they are expected to be and will carry out a leadership that’s consistent with their desired self-image. Scholarly significance: Numerous Swedish teachers resign in the beginning of their careers as the reality-check hits them of being unprepared for the leadership required of them (Akin-Little & Little, 2008; Colnerud, Karlsson & Szklarski, 2008). Despite the number of academically proposed approaches to classroom management all Swedish pre-service teachers do not successfully manage to apply those approaches as practical knowledge in the classroom. As academics we need to explore new ways of supporting pre-service teachers in learning how to perform classroom management as they after graduation will join a community of practice that is currently unable to support them in that growth.

  • 21.
    Gremyr, Ida
    et al.
    Chalmers University of Technology, Göteborg, Sweden).
    Elg, Mattias
    Linköping University, Department of Management and Engineering, Quality Technology and Management. Linköping University, The Institute of Technology. Linköping University, HELIX Vinn Excellence Centre.
    A developmental view on implementation of quality management concepts2014In: International Journal of Quality and Service Sciences, ISSN 1756-669X, E-ISSN 1756-6703, Vol. 6, no 2/3, 143-154 p.Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to examine the value of a developmental learning view on implementation of quality management (QM) concepts. QM concepts are common in various organizations; some implement them smoothly, others struggle and sometimes even abandon the initiatives. What is then a successful implementation – is it the use a specific QM method as a standard problem solving approach, or is it that learning has occurred during implementation?

    Design/methodology/approach – The paper is based on an illustrative case study carried out at a hospital in western Sweden. The data have been collected through about 130 hours of participation in project work by the first author and through seven face-to-face interviews of about one hour each.

    Findings – It is shown that a Design for Six Sigma pilot project with a narrow view on implementation could be regarded as a failure, but it gave rise to much learning and new improved ways of working. Hence, it is argued that a developmental view on implementation can support learning by an emergent and experimental approach to implementation processes.

    Originality/value – Much research has been done on how to increase the success rate of implementations of QM initiatives, e.g. procedures to follow to reach an outcome where the new way of working is standard procedure. Less research has problematized the implementation process, questioning what a successful outcome of an implementation is.

  • 22.
    Angelakis, Vangelis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Sajid, Muhammad
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Siddiqui, Imran
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A distributed, load-aware, power and frequency bargaining protocol for LTE-based networks2012In: 2012 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), Piscataway, NJ, USA: IEEE , 2012, 6525-6529 p.Conference paper (Refereed)
    Abstract [en]

    A distributed, load-aware, joint power and frequency allocation protocol is introduced for LTE-based cellular networks, and system-level simulations are performed. Our proposed scheme aims to cooperatively limit the impact of Fractional Frequency Reuse (FFR) on the center users throughput compared to the Reuse 1 scheme, while providing sufficient throughput for the edge users. This is achieved through an asynchronous, lightweight scheme of local message exchange between neighboring LTE eNodeBs. The proposed scheme facilitates a type of "bargain" where an overloaded sector requests permission to utilize its neighbors edge bands for its center users at a limited set of transmit power levels. Grants are generated at each neighbor by solving a small-scale optimization problem. Using an LTE simulator we evaluate our scheme on a network with 21 sectors of varying load patterns. The proposed schemes performance for center users is consistently improved with respect to FFR-3, while for edge users the performance degradation is controlled by a parameter we set in the optimization problems definitions; compared to Reuse 1 edge users still have gains. Specifically, we observed up to a 46% gain in the sectors center throughput with a cost below 9% at the edges when compared to the classic FFR scheme, while the overall system throughput goes up by up to 26% in heavily loaded scenarios.

  • 23.
    Kessler, Christoph
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Bednarski, Andrzej
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    A Dynamic Programming Approach to Optimal Integrated Code Generation2001In: ACM SIGPLAN Workshop on Languages, Compilers, and Tools for Embedded Systems LCTES2001,2001, New York, USA: ACM , 2001, 165-174 p.Conference paper (Refereed)
    Abstract [en]

    Phase-decoupled methods for code generation are the state of the art in compilers for standard processors but generally produce code of poor quality for irregular target architectures such as many DSPs. In that case, the generation of efficient code requires the simultaneous solution of the main subproblems instruction selection, instruction scheduling, and register allocation, as an integrated optimization problem. In contrast to compilers for standard processors, code generation for DSPs can afford to spend much higher resources in time and space on optimizations. Today, most approaches to optimal code generation are based on integer linear programming, but these are either not integrated or not able to produce optimal solutions except for very small problem instances. We report on research in progress on a novel method for fully integrated code generation that is based on dynamic programming. In particular, we introduce the concept of a time profile. We focus on the basic block level where the data dependences among the instructions form a DAG. Our algorithm aims at combining time-optimal scheduling with optimal instruction selection, given a limited number of general-purpose registers. An extension for irregular register sets, spilling of register contents, and intricate structural constraints on code compaction based on register usage is currently under development, as well as a generalization for global code generation. A prototype implementation is operational, and we present first experimental results that show that our algorithm is practical also for medium-size problem instances. Our implementation is intended to become the core of a future, retargetable code generation system.

  • 24.
    Khayyeri, Hanifeh
    et al.
    Lund University, Sweden.
    Gustafsson, Anna
    Lund University, Sweden.
    Heuijerjans, Ashley
    Eindhoven University of Technology, Netherlands.
    Matikainen, Marko K.
    Lappeenranta University of Technology, Finland.
    Julkunen, Petro
    Kuopio University Hospital, Finland; University of Eastern Finland, Finland.
    Eliasson, Pernilla
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Aspenberg, Per
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Orthopaedics in Linköping.
    Isaksson, Hanna
    Lund University, Sweden.
    A Fibre-Reinforced Poroviscoelastic Model Accurately Describes the Biomechanical Behaviour of the Rat Achilles Tendon2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 6, e0126869Article in journal (Refereed)
    Abstract [en]

    Background Computational models of Achilles tendons can help understanding how healthy tendons are affected by repetitive loading and how the different tissue constituents contribute to the tendons biomechanical response. However, available models of Achilles tendon are limited in their description of the hierarchical multi-structural composition of the tissue. This study hypothesised that a poroviscoelastic fibre-reinforced model, previously successful in capturing cartilage biomechanical behaviour, can depict the biomechanical behaviour of the rat Achilles tendon found experimentally. Materials and Methods We developed a new material model of the Achilles tendon, which considers the tendons main constituents namely: water, proteoglycan matrix and collagen fibres. A hyperelastic formulation of the proteoglycan matrix enabled computations of large deformations of the tendon, and collagen fibres were modelled as viscoelastic. Specimen-specific finite element models were created of 9 rat Achilles tendons from an animal experiment and simulations were carried out following a repetitive tensile loading protocol. The material model parameters were calibrated against data from the rats by minimising the root mean squared error (RMS) between experimental force data and model output. Results and Conclusions All specimen models were successfully fitted to experimental data with high accuracy (RMS 0.42-1.02). Additional simulations predicted more compliant and soft tendon behaviour at reduced strain-rates compared to higher strain-rates that produce a stiff and brittle tendon response. Stress-relaxation simulations exhibited strain-dependent stress-relaxation behaviour where larger strains produced slower relaxation rates compared to smaller strain levels. Our simulations showed that the collagen fibres in the Achilles tendon are the main load-bearing component during tensile loading, where the orientation of the collagen fibres plays an important role for the tendons viscoelastic response. In conclusion, this model can capture the repetitive loading and unloading behaviour of intact and healthy Achilles tendons, which is a critical first step towards understanding tendon homeostasis and function as this biomechanical response changes in diseased tendons.

  • 25.
    Söderberg, Johan
    Linköping University, Department of Management and Engineering, Mechanics. Linköping University, The Institute of Technology.
    A finite element method for calculating load distributions in bolted joint assemblies2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Bolted joints are often the most critical parts with respect to fatigue life of structures. Therefore, it is important to analyze these components and the forces they are subjected to.

    A one-dimensional nite element model of a bolted joint is created and implemented as a program module in the Saab software `DIM', together with a complete graphical user interface allowing the user to generate the structure freely, and to apply both mechanical and thermal loads.

    Available methods for calculating fastener exibility are reviewed. The ones derived by Grumman, Huth and Barrois are implemented in the module, and can thus be used when dening a geometry representing a bolted joint assembly. Investigations have shown that it cannot be said that either method is generally better than the other. Calculated properties of interest include the fastener forces, plate bearing and bypass loads, and - for simpler geometries without thermal loads - the load distribution between rows of fasteners.

    The program is fully functional and yields numerically accurate results for the most commonly used joints where fasteners connect two or three plates each. It has limited functionality on geometries with fasteners connecting four or more plates and for a certain loading combination also for three plates, due to the tilting of the fasteners not being accounted for in the model for these cases. Also, there is no explicit method available for nding an accurate value for the fastener exibility for these, less common, joint structures.

  • 26.
    Jung, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Frisk, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, The Institute of Technology.
    A flywheel manufacturing error compensation algorithm for engine misfire detection2016In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 47, 37-47 p.Article in journal (Refereed)
    Abstract [en]

    A commonly used signal for engine misfire detection is the crankshaft angular velocity measured at the flywheel. However, flywheel manufacturing errors result in vehicle-to-vehicle variations in the measurements and have a negative impact on the misfire detection performance, where the negative impact is quantified for a number of vehicles. A misfire detection algorithm is proposed with flywheel error adaptation in order to increase robustness and reduce the number of mis-classifications. Since the available computational power is limited in a vehicle, a filter with low computational load, a Constant Gain Extended Kalman Filter, is proposed to estimate the flywheel errors. Evaluations using measurements from vehicles on the road show that the number of mis-classifications is significantly reduced when taking the estimated flywheel errors into consideration.

  • 27.
    Kuiper, Erik
    et al.
    Saab Aeronautical, Linkoping, Sweden .
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A framework for performance analysis of geographic delay-tolerant routing2012In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, no 184Article in journal (Refereed)
    Abstract [en]

    A major tool used for evaluating routing protocols in ad hoc and delay-tolerant networks is simulation. Whereas the results from simulations give good insights, they are limited to the specific scenario set-up that is used. If the scenario changes, new and often time-consuming simulations have to be run. Moreover, the simulation time in packet-level simulators with fairly realistic physical layer implementation, such as ns-2, generally grows rapidly in the number of nodes. This practically limits the number of nodes in a simulation, even if the limit can be extended by the use of simulation federations. Larger scenarios can also be facilitated by the use of more abstraction in the physical layer; abstractions that may impact the validity of the results. In this article, we present the forward-wait framework--a mathematical model describing the packet movements for opportunistic geographic delay-tolerant routing protocols. By describing packet movements as a sequence of alternating forwarding and waiting phases, the framework can accurately predict the routing performance. Key input parameters to the framework are random variables describing the forwarding and waiting phases. We show how the properties of the random variables can be derived, both via abstract modeling and small scale ns-2 simulation data. The model is then used to demonstrate the prediction capabilities of the framework in providing results that are close to the (much slower) packet-level simulations.

  • 28.
    Olstam, Johan
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lundgren, Jan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Adlers, Mikael
    Swedish National Road and Transport Research Institute (VTI), VTI, SE-581 95 Linköping, Sweden.
    Matstoms, Pontus
    Swedish National Road and Transport Research Institute (VTI), VTI, SE-581 95 Linköping, Sweden.
    A Framework for Simulation of Surrounding Vehicles in Driving Simulators2008In: ACM Transactions on Modeling and Computer Simulation, ISSN 1049-3301, Vol. 18, no 3Article in journal (Refereed)
    Abstract [en]

    This article describes a framework for generation and simulation of surrounding vehicles in a driving simulator. The proposed framework generates a traffic stream, corresponding to a given target flow and simulates realistic interactions between vehicles. The framework is based on an approach in which only a limited area around the driving simulator vehicle is simulated. This closest neighborhood is divided into one inner area and two outer areas. Vehicles in the inner area are simulated according to a microscopic simulation model including advanced submodels for driving behavior while vehicles in the outer areas are updated according to a less time-consuming mesoscopic simulation model. The presented work includes a new framework for generating and simulating vehicles within a moving area. It also includes the development of an enhanced model for overtakings and a simple mesoscopic traffic model. The framework has been validated on the number of vehicles that catch up with the driving simulator vehicle and vice versa. The agreement is good for active and passive catch-ups on rural roads and for passive catch-ups on freeways, but less good for active catch-ups on freeways. The reason for this seems to be deficiencies in the utilized lane-changing model. It has been verified that the framework is able to achieve the target flow and that there is a gain in computational time of using the outer areas. The framework has also been tested within the VTI Driving simulator III.

  • 29.
    Angelakis, Vangelis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Chen, Lei
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A Fully Decentralized and Load-Adaptive Fractional Frequency Reuse Scheme2011In: Modeling, Analysis & Simulation of Computer and Telecommunication Systems (MASCOTS), 2011 IEEE 19th International Symposium on, 2011, 425-428 p.Conference paper (Refereed)
    Abstract [en]

    A new fully decentralized dynamic fractional frequency reuse (FFR)-based scheme for cellular OFDMA networks is introduced. FFR is a technique to mitigate inter-cell interference to improve the throughput of interference-limited users on the cell edge, to the expense of the rest of the cell's users and the aggregate throughput. The proposed scheme aims to limit the FFR-incurred loss of the center users' throughput, while still providing sufficient bandwidth for the cell edge users' communication. This is done by local information sharing and distributed optimization. The resulting flexibility of frequency reuse can be especially beneficial in scenarios with non-uniform and time-varying load. The optimization task is accomplished by solving a knapsack problem in each cell, where the goal is to maximize the center throughput while maintaining acceptable degradation on the cell edge with respect to the original FFR allocation. The performance improvement resulting from the distributed and dynamic FFR scheme is demonstrated by snapshot simulations on an 81-cells network with asymmetric cell load. The proposed scheme achieves up to a 62% gain in cell-center throughput with a cost of no more than 18% at the edges when compared to the classic FFR scheme. The overall system throughput improvement ranges from 22% to 58%.

  • 30.
    Kindberg, Elin
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Molecular Virology. Linköping University, Faculty of Health Sciences.
    Vene, Sirkka
    Swedish Institute Infectious Disease Control.
    Mickiene, Aukse
    Kaunas University of Medicine.
    Lundkvist, Ake
    Swedish Institute Infectious Disease Control.
    Lindquist, Lars
    Karolinska University.
    Svensson, Lennart
    Linköping University, Department of Clinical and Experimental Medicine, Molecular Virology. Linköping University, Faculty of Health Sciences.
    A Functional Toll-Like Receptor 3 Gene (TLR3) May Be a Risk Factor for Tick-borne Encephalitis Virus (TBEV) Infection2011In: JOURNAL OF INFECTIOUS DISEASES, ISSN 0022-1899, Vol. 203, no 4, 523-528 p.Article in journal (Refereed)
    Abstract [en]

    Background. Tick-borne encephalitis virus (TBEV) infections may be asymptomatic or cause severe symptoms in the central nervous system. A mutation in the chemokine receptor 5 gene has been associated with increased risk of TBE but explains only a limited number of cases. Investigations of further risk factors are needed. Method. To investigate the importance of the innate immune response, we analyzed 128 TBE patients, 77 patients with aseptic meningoencephalitis (AME) and 135 healthy controls, for 3mutations: 2 in the Toll-like receptor 3 (TLR3) gene and 1 in the 2-5-oligoadenylate synthetase (OAS1) gene. Results. Although no association was found between the mutation in the OAS1 gene and TBE, the genotype distribution ofrs3775291, a mutation in TLR3, differed significantly between TBE patients and controls; 61%, 32%, and 7% of the TBE patients were carriers of the wild-type, heterozygous, and mutant genotype of rs3775291, respectively. The corresponding percentages among healthy controls (n = 126) were 52%, 29%, and 19% (P = .02), and among AME patients (n = 75) were 47%, 32%, and 21% (P = .009). Additionally, the wild-type rs3775291 allele was more common among TBE patients than among healthy controls (allele frequency, .768 vs .663; P = .01). Conclusion. A functional TLR3 is a risk factor for TBEV infection.

  • 31.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Kircher, Albert
    Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    A Gaze-Based Driver Distraction Warning System and Its Effect on Visual Behavior2013In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 14, no 2, 965-973 p.Article in journal (Refereed)
    Abstract [en]

    Driver distraction is a contributing factor to many crashes; therefore, a real-time distraction warning system should have the potential to mitigate or circumvent many of these crashes. The objective of this paper is to investigate the usefulness of a real-time distraction detection algorithm called AttenD. The evaluation is based on data from an extended field study comprising seven drivers who drove on an average of 4351 +/- 2181 km in a naturalistic setting. Visual behavior was investigated both on a global scale and on a local scale in the surroundings of each warning. An increase in the percentage of glances at the rear-view mirror and a decrease in the amount of glances at the center console were found. The results also show that visual time sharing decreased in duration from 9.94 to 9.20 s due to the warnings, that the time from fully attentive to warning decreased from 3.20 to 3.03 s, and that the time from warning to full attentiveness decreased from 6.02 to 5.46 s. The limited number of participants does not allow any generalizable conclusions, but a trend toward improved visual behavior could be observed. This is a promising start for further improvements of the algorithm and the warning strategy.

  • 32.
    Josefson, Bengt
    Linköping University, The Institute of Technology. Linköping University, Department of Mathematics, Applied Mathematics.
    A Gelfand-Phillips space not containing l(1) whose dual ball is not weak* sequentially compact2001In: Glasgow Mathematical Journal, ISSN 0017-0895, Vol. 43, 125-128 p.Article in journal (Refereed)
    Abstract [en]

    A set D in a Banach space E is called limited if pointwise convergent sequences of linear functionals converge uniformly on D and E is called a GP-space (after Gelfand and Phillips) if every limited set in E is relatively compact. Banach spaces with weak* sequentially compact dual balls (W*SCDB for short) are GP-spaces and l(1)(A) is a GP-space without W*SCDB. Disproving a conjecture of Rosenthal and inspired by James tree space, Hagler and Odell constructed a class of Banach spaces ([HO]-spaces) without both W*SCDB and subspaces isomorphic to l(1). Schlumprecht has shown that there is a subclass of the [HO]-spaces which are also GP-spaces. It is not clear however if any [HO]-construction yields a GP-space-in fact it is not even clear that W*SCDB double left right arrow GP-space is false in general for the class of Banach spaces containing no subspace isomorphic to l(1). In this note the example of Hagler and Odell is modified to yield a GP-space without W*SCDB and without an isomorphic copy of l(1).

  • 33.
    Fogelberg Eriksson, Anna
    Linköping University, Department of Behavioural Sciences and Learning, Education and Sociology. Linköping University, Department of Behavioural Sciences and Learning, Work and Working Life. Linköping University, Faculty of Arts and Sciences. Linköping University, HELIX Vinn Excellence Centre.
    A gender perspective as trigger and facilitator of innovation2014In: International Journal of Gender and Entrepreneurship, ISSN 1756-6266, Vol. 6, no 2, 163-180 p.Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to explore whether a gender perspective contributes to or functions as a driving force for innovations in organizations. The following questions are addressed: how can a gender perspective generate innovations and what are the conditions that favour innovations driven by a gender perspective?

    Design/methodology/approach – This study builds on a qualitative case study of an upper secondary school in Sweden, which has been showcased as a good example of gender awareness and gender mainstreaming in schools. Semi-structured interviews with representatives of the school were conducted and documents were analysed.

    Findings – The gender perspective contributed to innovations by triggering them and supporting the innovative processes, ensuring that the innovations did not stop at essentialist solutions. New ways of performing core processes were developed with the innovative leverage of the gender perspective. The perspective must be actively used and integrated into the core processes if it is to work properly, which was the case in this school.

    Research limitations/implications – This study indicates the importance of conducting further studies on innovations in the public sector as well as acknowledging gender in innovation studies, not least because this study focuses on a local case in a specific national context.

    Practical implications – This school exemplifies the use of a gender perspective as a driving force for innovations in organizations. The case points to important organizational conditions for innovation and actual gender-aware innovations.

    Originality/value – The study expands the understanding of innovation(s) in organizations and elaborates on the gendered dimensions of innovation as both process and product.

  • 34.
    Sederholm Lawesson, Sofia
    et al.
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Cardiology in Linköping.
    Alfredsson, Joakim
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Cardiology in Linköping.
    Fredrikson, Mats
    Linköping University, Department of Clinical and Experimental Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Swahn, Eva
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Cardiology in Linköping.
    A gender perspective on short- and long term mortality in ST-elevation myocardial infarction: a report from the SWEDEHEART register2013In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 18, no 2, 1041-1047 p.Article in journal (Refereed)
    Abstract [en]

    Background: Previous studies of patients admitted for ST-elevation myocardial infarction [STEMI] have indicated that women have a higher risk of early mortality than do men. These studies have presented limited information on gender related differences in the short term and almost no information on the long term. Methods and results: We analysed a prospective, consecutively included STEMI population consisting of 54,146 patients (35% women). This population consists of almost all patients hospitalised in Sweden between January 1, 1995 and December 31, 2006 as recorded in the SWEDEHEART register (formerly RIKS-HIA). Follow-up time ranged from one to 13 years (mean 4.6). Women had a lower probability of being given reperfusion therapy, odds ratio [OR] 0.83 (95% confidence interval [CI] 0.79-0.88). During the time these STEMI patients were in the hospital, 13% of the women and 7% of men died, multivariable adjusted OR 1.21 (95% CI 1.11-1.32). During the follow up period, 46% of the women died as compared with 32% of the men. There was, however, no gender difference in age-adjusted risk of long term mortality (hazard ratio [HR] 0.98, 95% CI 0.95-1.01) whereas the multivariable adjusted risk was lower in women (HR 0.92, 95% CI 0.89-0.96). The long term risk of re-infarction was the same in men and women (HR 0.98, 95% CI 0.93-1.03) whereas men in the youngest group had a higher risk than women in that age group (HR 0.82, 95% CI 0.72-0.94). Conclusion: In STEMI, women had a higher risk of in-hospital mortality but the long-term risk of death was higher in men. More studies are needed in the primary percutaneous coronary intervention (pPCI) era that are designed to determine why women fare worse than men after STEMI during the first phase when they are in hospital

  • 35.
    Benito-Sipos, Jonathan
    et al.
    University Autonoma of Madrid.
    Estacio-Gomez, Alicia
    University Autonoma of Madrid.
    Moris-Sanz, Marta
    University Autonoma of Madrid.
    Baumgardt, Magnus
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Developmental Biology, IKE.
    Thor, Stefan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Developmental Biology, IKE.
    J Diaz-Benjumea, Fernando
    University Autonoma of Madrid.
    A genetic cascade involving klumpfuss, nab and castor specifies the abdominal leucokinergic neurons in the Drosophila CNS2010In: DEVELOPMENT, ISSN 0950-1991, Vol. 137, no 19, 3327-3336 p.Article in journal (Refereed)
    Abstract [en]

    Identification of the genetic mechanisms underlying the specification of large numbers of different neuronal cell fates from limited numbers of progenitor cells is at the forefront of developmental neurobiology. In Drosophila, the identities of the different neuronal progenitor cells, the neuroblasts, are specified by a combination of spatial cues. These cues are integrated with temporal competence transitions within each neuroblast to give rise to a specific repertoire of cell types within each lineage. However, the nature of this integration is poorly understood. To begin addressing this issue, we analyze the specification of a small set of peptidergic cells: the abdominal leucokinergic neurons. We identify the progenitors of these neurons, the temporal window in which they are specified and the influence of the Notch signaling pathway on their specification. We also show that the products of the genes klumpfuss, nab and castor play important roles in their specification via a genetic cascade.

  • 36.
    Benito-Sipos, Jonathan
    et al.
    Centro de Biología Molecular-Severo Ochoa, Universidad Autónoma de Madrid-C.S.I.C., Madrid, Spain.
    Estacio-Gómez, Alicia
    Centro de Biología Molecular-Severo Ochoa, Universidad Autónoma de Madrid-C.S.I.C., Madrid, Spain.
    Moris-Sanz, Marta
    Centro de Biología Molecular-Severo Ochoa, Universidad Autónoma de Madrid-C.S.I.C., Madrid, Spain.
    Baumgardt, Magnus
    Linköping University, Department of Clinical and Experimental Medicine, Developmental Biology, IKE. Linköping University, Faculty of Health Sciences.
    Thor, Stefan
    Linköping University, Department of Clinical and Experimental Medicine, Developmental Biology, IKE. Linköping University, Faculty of Health Sciences.
    Díaz-Benjumea, Fernando J.
    Centro de Biología Molecular-Severo Ochoa, Universidad Autónoma de Madrid-C.S.I.C., Madrid, Spain.
    A genetic cascade involving the genes klumfuss, nab and castor specifies the abdominal leucokinergic neurons in the Drosophila CNSManuscript (preprint) (Other academic)
    Abstract [en]

    The genetic mechanisms underlying the specification of a large number of different cell fates starting from a limited group of progenitor cells are a major focus of investigations of central nervous system development. In Drosophila the identities of the different neuronal progenitor cells, the neuroblasts, are specified by a combination of spatial and temporal factors. But how each neuroblast gives rise to a specific repertoire of cell types via a precise programme is poorly understood. In this report we analyse the specification of a small set of peptidergic cells, the abdominal leucokinergic neurons. We identify the progenitors of these neurons, the temporal window in which they are specified, and the influence of the Notch signalling pathway on their specification. We also show that the products of the genes klumfuss, nab and castor play important roles in their specification via a genetic cascade.

  • 37.
    Hinkel, Jochen
    et al.
    Global Climate Forum (GCF), Germany .
    Nicholls, Robert J.
    University of Southampton, England .
    Tol, Richard S. J.
    University of Sussex, England Vrije University of Amsterdam, Netherlands .
    Wang, Zheng B.
    Delft University of Technology, Netherlands Deltares, Netherlands .
    Hamilton, Jacqueline M.
    University of Hamburg, Germany .
    Boot, Gerben
    Deltares, Netherlands .
    Vafeidis, Athanasios T.
    University of Kiel, Germany .
    McFadden, Loraine
    Middlesex University, England .
    Ganopolski, Andrey
    Potsdam Institute Climate Impact Research PIK, Germany .
    Klein, Richard
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Thematic Studies, Centre for Climate Science and Policy Research. Stockholm Environment Institute, Stockholm, Sweden.
    A global analysis of erosion of sandy beaches and sea-level rise: An application of DIVA2013In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 111, 150-158 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a first assessment of the global effects of climate-induced sea-level rise on the erosion of sandy beaches, and its consequent impacts in the form of land loss and forced migration of people. We consider direct erosion on open sandy coasts and indirect erosion near selected tidal inlets and estuaries, using six global mean sea-level scenarios (in the range of 0.2-0.8 m) and six SRES socio-economic development scenarios for the 21st century. Impacts are assessed both without and with adaptation in the form of shore and beach nourishment, based on cost-benefit analysis that includes the benefits of maintaining sandy beaches for tourism. Without nourishment, global land loss would amount to about 6000-17,000 km(2) during the 21st century, leading to 1.6-5.3 million people being forced to migrate and migration costs of US$ 300-1000 billion (not discounted). Optimal beach and shore nourishment would cost about US$ 65-220 billion (not discounted) during the 21st century and would reduce land loss by 8-14%, forced migration by 56-68% and the cost of forced migration by 77-84% (not discounted). The global share of erodible coast that is nourished increases from about 4% in 2000 to 18-33% in 2100, with beach nourishment being 3-4 times more frequent than shore nourishment, reflecting the importance of tourism benefits. In absolute terms, with or without nourishment, large counties with long shorelines appear to have the largest costs, but in relative terms, small island states appear most impacted by erosion. Considerable uncertainty remains due to the limited availability of basic coastal geomorphological data and models on a global scale. Future work should also further explore the effects of beach tourism, including considering sub-national distributions of beach tourists.

  • 38.
    Sabe, Emelie
    Linköping University, Department of Science and Technology.
    A Haptic Guidance System for Stroke Rehabilitation2007Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Stroke is the third largest cause of death in Sweden. In 2005, 30.000 people in Sweden suffered from a stroke. The consequences of a stroke varies, but the most common disability among stroke survivors is abnormal reaching movements, which is the primer reason for limitations in activities of everyday living. Rehabilitation is essential in order to get back to everyday life.

    Physical assistance (or guidance) is used in rehabilitation by physiotherapists and occupational therapists to help a patient through a dicult movement for example. Today, this guidance is limited to be performed by medical personnel. With the technology of virtual environments (VE) and haptics – force feedback from a computer – there is a possibility to create guidance which does not need medical personnel. This should be used as a complement to the traditional therapy.

    The intention of this work is to create an invisible guidance eld, which should guide a patient's hand to a desired movement pattern, i.e. aid the patient to perform a task in a virtual environment with haptics. This guidance is added to an already existing assessment tool, which is a part of the Curictus AB rehabilitation system. The guiding system is implemented using SenseGraphics AB's H3D API.

    To create the feeling of guidance and a guidance eld, the Volume Haptics Toolkit, developed by Dr. Karljohan Lundin Palmerius at Linköping University, was used. The basic idea of the algorithm is to calculate an orientation vector, for every position, in which direction the guidance should guide the patient. The guidance, which is generated via a haptic device, is adaptive to the patient's movements and always guides the patient towards the target in a smooth trajectory.

  • 39.
    Ehliar, Andreas
    et al.
    Linköping University, Department of Electrical Engineering.
    Eilert, Johan
    Linköping University, Department of Electrical Engineering.
    A hardware MP3 decoder with low precision floating point intermediate storage2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The effects of using limited precision floating point for intermediate storage in an embedded MP3 decoder are investigated in this thesis. The advantages of using limited precision is that the values need shorter word lengths and thus a smaller memory for storage.

    The official reference decoder was modified so that the effects of different word lengths and algorithms could be examined. Finally, a software and hardware prototype was implemented that uses 16-bit wide memory for intermediate storage. The prototype is classified as a limited accuracy MP3 decoder. Only layer III is supported. The decoder could easily be extended to a full precision MP3 decoder if a corresponding increase in memory usage was accepted.

  • 40.
    Warnquist, Håkan
    et al.
    Linköping University, Department of Computer and Information Science, KPLAB - Knowledge Processing Lab. Linköping University, The Institute of Technology.
    Nyberg, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    A Heuristic for Near-Optimal Troubleshooting Using AO*2008In: Proceedings of the International Workshop on the Principles of Diagnosis, 2008Conference paper (Refereed)
    Abstract [en]

    When troubleshooting malfunctioning technical equipment, the task is to locate faults and make repairsuntil the equipment functions properly again. The AO* algorithm can be used to find troubleshootingstrategies that are optimal in the sense that the expected cost of repair is minimal. We have adaptedthe AO* algorithm for troubleshooting in the automotive domain with limited time. We propose a newheuristic based on entropy. By using this heuristic, near-optimal strategies can be found within a fixedtime limit. This is shown in empirical studies on a fuel injection system of a truck. In these results, theAO* algorithm using the new heuristic, performs better than other troubleshooting algorithms.

  • 41.
    Jeppsson-Grassman, Eva
    et al.
    Linköping University, Department of Social and Welfare Studies, NISAL - National Institute for the Study of Ageing and Later Life. Linköping University, Faculty of Arts and Sciences.
    Taghizadeh Larsson, Annika
    Linköping University, Department of Social and Welfare Studies, NISAL - National Institute for the Study of Ageing and Later Life. Linköping University, Faculty of Arts and Sciences.
    “A home away from home”: The role of the Church of Sweden Abroad for Swedish migrants2013In: New Religiosity in Migration, 2013, 38-41 p.Conference paper (Refereed)
    Abstract [en]

    According to some studies, Sweden is one of the most secularized countries in the world. with low church attendance. For most Swedes, their contact with the church is limited to traditional rites. How are we then to understand that quite a few Swedes seem to act much like immigrant groups from less secularized nations, by turning to the ethnic church and to religious practices while moving – fully or part time – to foreign countries?

    The aim of the presentation is to discuss this question, based on results from a project in which the role of the Church of Sweden   Abroad has been explored. The Church of Sweden has a long traditions of creating parishes abroad, mainly in the larger European cities and in connection with harbors, as Seaman`s Churches. Since some decades, however, the Church has started to follow the streams of tourists and elderly migrants and parishes have been established, mainly in Southern Europe and, lately in Asian countries.

    The presentation will be based on a project consisting of three studies: 1) A qualitative case study, 2) A mapping of the web sites of all 45 parishes, and 3) An internet-based survey of all parishes. An interesting pattern turned out to be  that many church visitors who initially seemed to be attracted by the (Swedish) “home away from home”  that the parish offered through e.g. “Swedish coffee”, eventually began to participate regularly in the church services, even in Holy Communion.

     

     

  • 42.
    Flisberg, Patrik
    et al.
    The Forestry Research Institute of Sweden, Uppsala, Sweden.
    Lidén, Bertil
    The Forestry Research Institute of Sweden, Uppsala, Sweden.
    Rönnqvist, Mikael
    The Forestry Research Institute of Sweden, Uppsala, Sweden and Norwegian School of Economics and Business Administration, Bergen, Norway.
    A hybrid method based on linear programming and tabu search for routing of logging trucks2009In: Computers & Operations Research, ISSN 0305-0548, Vol. 36, no 4, 1122-1144 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider an operational routing problem to decide the daily routes of logging trucks in forestry. This industrial problem is difficult and includes aspects such as pickup and delivery with split pickups, multiple products, time windows, several time periods, multiple depots, driver changes and a heterogeneous truck fleet. In addition, the problem size is large and the solution time limited. We describe a two-phase solution approach which transforms the problem into a standard vehicle routing problem with time windows. In the first phase, we solve an LP problem in order to find a destination of flow from supply points to demand points. Based on this solution, we create transport nodes which each defines the origin(s) and destination for a full truckload. In phase two, we make use of a standard tabu search method to combine these transport nodes, which can be considered to be customers in vehicle routing problems, into actual routes. The tabu search method is extended to consider some new features. The solution approach is tested on a set of industrial cases from major forest companies in Sweden.

  • 43.
    Kindborg, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, MDI - Interaction and Service Design Research Group. Linköping University, The Institute of Technology.
    Åberg, Johan
    Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems. Linköping University, The Institute of Technology.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems. Linköping University, The Institute of Technology.
    A lightweight agent framework for interactive multi-agent applications1999In: Proceedings of Fourth International Conference on the Practical Application of Intelligent Agents and Multi-Agents, 1999, 1, 123-142 p.Conference paper (Refereed)
    Abstract [en]

    Usability issues are traditionally associated with user interfaces rather than with agent frameworks. We argue that the metaphors and models used in a framework will affect the thinking of the developer, and will influence the application design. Therefore, usability is of central importance for successful software development, and for reducing development and maintenance costs. We discuss the design and implementation of a lightweight agent framework for interactive multi-agent applications. A lightweight framework is advantageous for distributed interactive applications, for instance applications running on hand-held devices with limited memory. The design is based on minimalism and simplicity. We present the results from a usability study of the framework, where issues such as learnability and attitude have been evaluated. The study shows that minimalist design principles are useful for achieving understandable and navigable frameworks.

  • 44.
    Burdakov, Oleg
    et al.
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Martinez, JM
    Linkoping Univ, Dept Math, Div Optimizat, S-58183 Linkoping, Sweden Univ Campinas, UNICAMP, IMECC, Dept Appl Math, BR-13081970 Campinas, SP, Brazil Univ Nacl Cordoba, CIEM, Fac Matemat Astron & Fis, RA-5000 Cordoba, Argentina.
    Pilotta, EA
    Linkoping Univ, Dept Math, Div Optimizat, S-58183 Linkoping, Sweden Univ Campinas, UNICAMP, IMECC, Dept Appl Math, BR-13081970 Campinas, SP, Brazil Univ Nacl Cordoba, CIEM, Fac Matemat Astron & Fis, RA-5000 Cordoba, Argentina.
    A limited-memory multipoint symmetric secant method for bound constrained optimization2002In: Annals of Operations Research, ISSN 0254-5330, E-ISSN 1572-9338, Vol. 117, no 1-4, 51-70 p.Article in journal (Refereed)
    Abstract [en]

    A new algorithm for solving smooth large-scale minimization problems with bound constraints is introduced. The way of dealing with active constraints is similar to the one used in some recently introduced quadratic solvers. A limited-memory multipoint symmetric secant method for approximating the Hessian is presented. Positive-definiteness of the Hessian approximation is not enforced. A combination of trust-region and conjugate-gradient approaches is used to explore a useful negative curvature information. Global convergence is proved for a general model algorithm. Results of numerical experiments are presented.

  • 45.
    Ahlström, Christer
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Health Sciences.
    Länne, Toste
    Linköping University, Department of Medicine and Health Sciences, Physiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Health Sciences.
    Johansson, Anders
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Health Sciences.
    A method for accurate localization of the first heart sound and possible applications2008In: Physiological Measurement, ISSN 0967-3334, Vol. 29, no 3, 417-428 p.Article in journal (Refereed)
    Abstract [en]

    We have previously developed a method for localization of the first heart sound (S1) using wavelet denoising and ECG-gated peak-picking. In this study, an additional enhancement step based on cross-correlation and ECG-gated ensemble averaging (EA) is presented. The main objective of the improved method was to localize S1 with very high temporal accuracy in (pseudo-) real time. The performance of S1 detection and localization, with and without EA enhancement, was evaluated on simulated as well as experimental data. The simulation study showed that EA enhancement reduced the localization error considerably and that S1 could be accurately localized at much lower signal-to-noise ratios. The experimental data were taken from ten healthy subjects at rest and during invoked hyper- and hypotension. For this material, the number of correct S1 detections increased from 91% to 98% when using EA enhancement. Improved performance was also demonstrated when EA enhancement was used for continuous tracking of blood pressure changes and for respiration monitoring via the electromechanical activation time. These are two typical applications where accurate localization of S1 is essential for the results.

  • 46.
    Danielsson, Fredrik
    et al.
    Linköping University, Department of Electrical Engineering.
    Lindgren, Anders
    Linköping University, Department of Electrical Engineering.
    A method for collision handling for industrial robots2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master's thesis presents the development of a collision handling function for Motoman industrial robots and investigates further use of the developed software. When a collision occurs the arm is to be retracted to a safe home location and the job is to be restarted to resume the production. The retraction can be done manually, which demands that the operator has to have good knowledge in robot handling and it might be a time consuming task. To minimise the time for restarting the job after a collision and allowing employees that have limited knowledge in robot handling to retract and restart the job, Motoman provides an automatical retraction function. However, the retraction function may cause further collisions when used and therefor a new function for retracting the arm is needed. The new function is based on that the motion of the robot is recorded by sampling the servo values, which are then stored in a buffer. A job file is automatically created and loaded into the control system, and the position variables of the job file are updated using the contents of the buffer. This will ensure a safe retraction of the arm as long as the environment surrounding the robot remains the same.

    The developed software made it possible to control the robot in real-time by changing the buffer information, which has lead to a cognitive system called the Pathfinder. By initiating the Pathfinder function with at least a start and an end point, the function generates a collision free path between the start point and the end point. A pilot-study has also been made concerning integration of a vision system with the Pathfinder to increase the decision handling for the function.

  • 47.
    Klenkar, Goran
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    A Microarray Chip for Label-Free Detection of Narcotics2008In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, Vol. 391, no 5, 1679-1688 p.Article in journal (Refereed)
    Abstract [en]

    A protein array chip for label-free optical detection of low molecular weight compounds has been developed. As a proof of principle, the chip is proven capable of rapidly (approximately 1 min) determining hits from aqueous cocktails composed of four common narcotics, cocaine, ecstasy, heroin, and amphetamine, using imaging surface plasmon resonance (SPR) as the detection principle. The chip is produced by injecting a mixture of antibodies and letting them self-sort and bind to narcotic analog coupled proteins already present in a predefined pattern on the supporting substrate. An indirect detection method, where antibodies are displaced from the surface upon recognition of their corresponding narcotics, is used to obtain the optical contrast and thus a detectable SPR and/or ellipsometric signal. Two types of readouts are possible from the present setup: intensity SPR images and SPR/ellipsometric sensorgrams. Positive hits were routinely obtained for analyte concentrations of 50 pg/μL and the limit of detection, without any parameter optimizations, seems to fall in the range 0.5 pg/μL (1.4 nM) for heroin, 2.5 pg/μL (8.2 nM) for cocaine, and 5 pg/μL for the other two narcotics (26 nM for ecstasy and 37 nM for amphetamine). With improved readout possibilities (sampling frequency), signal evaluation algorithms, and antibody–antigen design strategies, we believe this limit can be further improved. The chip is shown to work for many measurement cycles with excellent reproducibility. Moreover, with a more advanced fluidic system, excess injected antibodies could be collected and reused for many cycles, which could make the running costs of the system very low. The chip is in no way limited to detection of narcotics. Other low molecular weight compounds could easily be detected on the same chip. For example, trinitrotoluene detection has already been demonstrated using our chip. Possible areas of application for the system are therefore envisaged in airport and underground transport security, customs, drug interdiction, forensics, and as warning alerts on military equipment and personnel.

  • 48.
    Kindberg, Elin
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Molecular Virology . Linköping University, Faculty of Health Sciences.
    Vene, Sirkka
    Swedish Institute for Infectious Disease Control and Karolinska Institutet, Stockholm, Sweden.
    Mickiene, Aukse
    Clinic of Infectious Diseases, Kaunas University of Medicine, Kaunas, Lithuania.
    Lundkvist, Åke
    Swedish Institute for Infectious Disease Control and Karolinska Institutet, Stockholm, Sweden.
    Lindquist, Lars
    Unit for Infectious Diseases, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
    Svensson, Lennart
    Linköping University, Department of Clinical and Experimental Medicine, Molecular Virology . Linköping University, Faculty of Health Sciences.
    A Missense Mutation in the Toll‐like Receptor 3 Gene (TLR3) is Associated with Decreased Risk of Tick‐borne EncephalitisManuscript (preprint) (Other (popular science, discussion, etc.))
    Abstract [en]

    Infections with tick‐borne encephalitis virus (TBEV) may be asymptomatic or cause severe symptoms from the central nervous system, such as meningitis or encephalitis. A mutation in the chemokine receptor 5 (CCR5) gene has been associated with increased risk of TBE but can only explain a limited number of cases and investigations of further risk factors are clearly needed. To investigate the importance of the innate immune response, 128 Lithuanian TBE patients with meningitis or encephalitis, 77 patients with aseptic meningoencephalitis (AME) and 135 healthy controls were analyzed for three mutations: two in the toll‐like receptor 3 (TLR3) gene and one in the 2´‐5´ oligoadenylate synthetase 1 (OAS1) gene. While no association was found between the mutation in OAS1 and TBE, the genotype distribution of one of the mutations in TLR3, rs3775291, differed significantly between the TBE patients and the controls. 61%, 32% and 7% of the TBE patients (n=127) were carriers of the wild‐type/wild‐type, heterozygous and mutant/mutant genotype of TLR3 rs3775291 genotype respectively. The corresponding percentages for healthy controls (n=126) were 52%, 29% and 19% (P=0.02) and for AME patients (n=75) 47%, 32% and 21% (P=0.009). The wild‐type rs3775291 allele was more common among TBE patients than healthy controls (allele frequency 0.768 vs. 0.663, P=0.01), suggesting that functional TLR3 is a risk factor for severe TBEV infection.

  • 49.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Rahm, Lars
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    A model study of the effects of sulfide-oxidizing bacteria (Beggiatoa spp.) on phosphorus retention processes in hypoxic sediments: implications for phosphorus management in the Baltic Sea2011In: Boreal environment research, ISSN 1239-6095, Vol. 16, no 3, 167-184 p.Article in journal (Refereed)
    Abstract [en]

    Ongoing eutrophication increases phosphorus storage in surficial sediments of the Baltic Sea which can then be released during hypoxic/anoxic events. Such sediments are suitable habitats for sulfide-oxidizing bacteria, Beggiatoa spp. The objective of this paper is to investigate the effects of these bacteria on the P retention processes in hypoxic sediments using a diagenetic model. This model simulates interactions of the processes controlling P mobility in the sediments with redox reactions from the Beggiatoa metabolism. Modeling results demonstrate that P retention capability is limited when dissolved iron is mineralized as iron sulfides in the sediments. In this regard, sulfide consumption by Beggiatoa spp. potentially decreases the rate of iron sulfide formation and consequently increases the P retention capability in local-scale sediment.

  • 50.
    Westin, C.-F.
    et al.
    Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States, Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA 02115, United States.
    Wigström, Lars
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Loock, T.
    Sjoqvist, L.
    Kikinis, R.
    Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
    Knutsson, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    A multielement RF coil for MRI guidance of interventional devices2001In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, Vol. 14, no 1, 56-62 p.Article in journal (Refereed)
    Abstract [en]

    Accurate localization of minimally invasive devices is critical to the success of interventional procedures. Device orientation and tip position are two of the most important pieces of information needed to define device location for magnetic resonance imaging (MRI)-guided interventional procedures. While a single one-element micro coil incorporated into an interventional device has proven to be effective in some applications, it can only supply tip position information. However, multiple positions on the device are necessary to also determine its orientation. For this purpose, a novel single micro coil design with three separate winding elements that provides both the device orientation and tip position is described in this study. Definition of MR scan planes, by using the device orientation and the target tissue location, permits automatic tracking of the insertion of the device. Furthermore, devices that include this coil design are permitted to bend to a limited extent. This makes the micro coil design appropriate for many flexible interventional devices. Reliable near-real-time tracking of three points on an interventional device is demonstrated on a 0.2T MRI system with modest gradient performance. Phantom and in vivo animal experiments are used to demonstrate the utility of this new coil design. © 2001 Wiley-Liss, Inc.

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