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  • Public defence: 2017-08-25 09:00 Campus US, Linköping
    Latorre, Malcolm
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    The Physical Axon: Modeling, Simulation and Electrode Evaluation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electrodes are used in medicine for detection of biological signals and for stimulating tissue, e.g. in deep brain stimulation (DBS). For both applications, an understanding of the functioning of the electrode, and its interface and interaction with the target tissue involved is necessary. To date, there is no standardized method for medical electrode evaluation that allows transferability of acquired data. In this thesis, a physical axon (Paxon) potential generator was developed as a device to facilitate standardized comparisons of different electrodes. The Paxon generates repeatable, tuneable and physiological-like action potentials from a peripheral nerve. It consists of a testbed comprising 40 software controlled 20 μm gold wires embedded in resin, each wire mimicking a node of Ranvier. ECG surface Ag-AgCl electrodes were systematically tested with the Paxon. The results showed small variations in orientation (rotation) and position (relative to axon position) which directly impact the acquired signal. Other electrode types including DBS electrodes can also be evaluated with the Paxon.

    A theoretical comparison of a single cable neuronal model with an alternative established double cable neuron model was completed. The output with regards to DBS was implemented to comparing the models. These models were configured to investigate electrode stimulation activity, and in turn to assess the activation distance by DBS for changes in axon diameter (1.5-10 μm), pulse shape (rectangular biphasic and rectangular, triangular and sinus monophasic) and drive strength (1-5 V or mA). As both models present similar activation distances, sensitivity to input shape and computational time, the neuron model selection for DBS could be based on model complexity and axon diameter flexibility. An application of the in-house neuron model for multiple DBS lead designs, in a patient-specific simulation study, was completed. Assessments based on the electric field along multiple sample planes of axons support previous findings that a fixed electric field isolevel is sufficient for assessments of tissue activation distances for a predefined axon diameter and pulse width in DBS.

    List of papers
    1. A Physical Action Potential Generator: Design, Implementation and Evaluation
    Open this publication in new window or tab >>A Physical Action Potential Generator: Design, Implementation and Evaluation
    2015 (English)In: Frontiers in Neuroscience, ISSN 1662-4548, E-ISSN 1662-453X, Vol. 9, 1-11 p., 371Article in journal (Refereed) Published
    Abstract [en]

    The objective was to develop a physical action potential generator (Paxon) with the ability to generate a stable, repeatable, programmable, and physiological-like action potential. The Paxon has an equivalent of 40 nodes of Ranvier that were mimicked using resin embedded gold wires (Ø = 20 μm). These nodes were software controlled and the action potentials were initiated by a start trigger. Clinically used Ag-AgCl electrodes were coupled to the Paxon for functional testing. The Paxon’s action potential parameters were tunable using a second order mathematical equation to generate physiologically relevant output, which was accomplished by varying the number of nodes involved (1 to 40 in incremental steps of 1) and the node drive potential (0 to 2.8V in 0.7 mV steps), while keeping a fixed inter-nodal timing and test electrode configuration. A system noise floor of 0.07 ± 0.01 μV was calculated over 50 runs. A differential test electrode recorded a peak positive amplitude of 1.5 ± 0.05 mV (gain of 40x) at time 196.4 ± 0.06 ms, including a post trigger delay. The Paxon’s programmable action potential like signal has the possibility to be used as a validation test platform for medical surface electrodes and their attached systems.

    Place, publisher, year, edition, pages
    Frontiers Research Foundation, 2015
    Keyword
    Action potential, biomedical electrode, electronic nerve model, nodes of Ranvier, ulnar nerve
    National Category
    Medical Engineering
    Identifiers
    urn:nbn:se:liu:diva-121086 (URN)10.3389/fnins.2015.00371 (DOI)
    Note

    Funding agencies| Linköping University; the Swedish Research Council (Grant No. 621-2013-6078)

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

    Available from: 2015-09-07 Created: 2015-09-07 Last updated: 2017-06-19Bibliographically approved
    2. Describing Measurement Behaviour of a Surface Ag-AgCl Electrode Using the Paxon Test Platform
    Open this publication in new window or tab >>Describing Measurement Behaviour of a Surface Ag-AgCl Electrode Using the Paxon Test Platform
    2016 (English)In: XIV MEDITERRANEAN CONFERENCE ON MEDICAL AND BIOLOGICAL ENGINEERING AND COMPUTING 2016, SPRINGER , 2016, Vol. 57, 442-445 p.Conference paper, (Refereed)
    Abstract [en]

    A better understanding of bioelectrodes can be acquired with extended testing, which will lead to better methodology and data quality. Today electrodes are evaluated for intraelectrode differences and performance with a traditional gain-phase method, while using the physical axon action potential generator (Paxon) test platform offers extended test possibilities. The direct gain-phase measurements are useful to extract the transfer function of the electrode, as well as some other base parameters. The Paxon test platform is a complementary method that tests electrodes under conditions that are more realistic, mimicking real measurement situations in comparison to the gain-phase method. The Paxon also allows tests to be performed beyond what the gain-phase methods can measure, for example electrode rotation, which would uncover variations in the symmetry of the electrode. When tested, the symmetry properties of the electrode, where the electrodes are rotated in steps of 90 degrees, resulted in a peak to peak variation in detected amplitude of 5.3 +/- 8.9 mV. Therefore, the Paxon appears to be a feasible test platform for characterizing electrodes beyond the gain-phase tests in a semiautomatic manner.

    Place, publisher, year, edition, pages
    SPRINGER, 2016
    Series
    IFMBE Proceedings, ISSN 1680-0737
    Keyword
    Electrode testing; Characterization; Coupling Parameters; Stability test; Axon potential
    National Category
    Medical Equipment Engineering
    Identifiers
    urn:nbn:se:liu:diva-129510 (URN)10.1007/978-3-319-32703-7_86 (DOI)000376283000086 ()978-3-319-32703-7 (ISBN)978-3-319-32701-3 (ISBN)
    Conference
    14th Mediterranean Conference on Medical and Biological Engineering and Computing (MEDICON)
    Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2017-06-19Bibliographically approved
    3. Investigation into Deep Brain Stimulation Lead Designs: A Patient-Specific Simulation Study
    Open this publication in new window or tab >>Investigation into Deep Brain Stimulation Lead Designs: A Patient-Specific Simulation Study
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    2016 (English)In: Brain Sciences, ISSN 2076-3425, E-ISSN 2076-3425, Vol. 6, no 3, 1-16 p.Article in journal (Refereed) Published
    Abstract [en]

    New deep brain stimulation (DBS) electrode designs offer operation in voltage and current mode and capability to steer the electric field (EF). The aim of the study was to compare the EF distributions of four DBS leads at equivalent amplitudes (3 V and 3.4 mA). Finite element method (FEM) simulations (n = 38) around cylindrical contacts (leads 3389, 6148) or equivalent contact configurations (leads 6180, SureStim1) were performed using homogeneous and patient-specific (heterogeneous) brain tissue models. Steering effects of 6180 and SureStim1 were compared with symmetric stimulation fields. To make relative comparisons between simulations, an EF isolevel of 0.2 V/mm was chosen based on neuron model simulations (n = 832) applied before EF visualization and comparisons. The simulations show that the EF distribution is largely influenced by the heterogeneity of the tissue, and the operating mode. Equivalent contact configurations result in similar EF distributions. In steering configurations, larger EF volumes were achieved in current mode using equivalent amplitudes. The methodology was demonstrated in a patient-specific simulation around the zona incerta and a “virtual” ventral intermediate nucleus target. In conclusion, lead design differences are enhanced when using patient-specific tissue models and current stimulation mode.

    Place, publisher, year, edition, pages
    MDPI, 2016
    Keyword
    deep brain stimulation (DBS), steering, patient-specific, electric field, finite element method, neuron model, brain model, zona incerta (ZI), electrode design
    National Category
    Medical Engineering
    Identifiers
    urn:nbn:se:liu:diva-131863 (URN)10.3390/brainsci6030039 (DOI)27618109 (PubMedID)
    Available from: 2016-10-11 Created: 2016-10-11 Last updated: 2017-06-19Bibliographically approved
  • Public defence: 2017-08-31 10:15 C3, C-huset, Linköping
    Munjulury, Raghu Chaitanya
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Knowledge-Based Integrated Aircraft Design: An Applied Approach from Design to Concept Demonstration2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The design and development of new aircraft are becoming increasingly expensive and timeconsuming. To assist the design process in reducing the development cost, time, and late design changes, the conceptual design needs enhancement using new tools and methods. Integration of several disciplines in the conceptual design as one entity enables to keep the design process intact at every step and obtain a high understanding of the aircraft concepts at early stages.

    This thesis presents a Knowledge-Based Engineering (KBE) approach and integration of several disciplines in a holistic approach for use in aircraft conceptual design. KBE allows the reuse of obtained aircrafts’ data, information, and knowledge to gain more awareness and a better understanding of the concept under consideration at early stages of design. For this purpose, Knowledge-Based (KB) methodologies are investigated for enhanced geometrical representation and enable variable fidelity tools and Multidisciplinary Design Optimization (MDO). The geometry parameterization techniques are qualitative approaches that produce quantitative results in terms of both robustness and flexibility of the design parameterization. The information/parameters from all tools/disciplines and the design intent of the generated concepts are saved and shared via a central database.

    The integrated framework facilitates multi-fidelity analysis, combining low-fidelity models with high-fidelity models for a quick estimation, enabling a rapid analysis and enhancing the time for a MDO process. The geometry is further propagated to other disciplines [Computational Fluid Dynamics (CFD), Finite Element Analysis (FEA)] for analysis. This is possible with an automated streamlined process (for CFD, FEM, system simulation) to analyze and increase knowledge early in the design process. Several processes were studied to streamline the geometry for CFD. Two working practices, one for parametric geometry and another for KB geometry are presented for automatic mesh generation.

    It is observed that analytical methods provide quicker weight estimation of the design and when coupled with KBE provide a better understanding. Integration of 1-D and 3-D models offers the best of both models: faster simulation, and superior geometrical representation. To validate both the framework and concepts generated from the tools, they are implemented in academia in several courses at Linköping University and in industry

    List of papers
    1. A knowledge-based integrated aircraft conceptual design framework
    Open this publication in new window or tab >>A knowledge-based integrated aircraft conceptual design framework
    2016 (English)In: CEAS Aeronautical Journal, ISSN 1869-5582, 1869-5590, Vol. 7, no 1, 95-105 p.Article in journal (Refereed) Published
    Abstract [en]

    "The conceptual design is the early stage of aircraft design process where results are needed fast, both analytically and visually so that the design can be analyzed and eventually improved in the initial phases. Although there is no necessity for a CAD model from the very beginning of the design process, it can be an added advantage to have the model to get the impression and appearance. Furthermore, this means that a seamless transition into preliminary design is achieved since the CAD model can guardedly be made more detailed. For this purpose, knowledge-based aircraft conceptual design applications Tango (Matlab) and RAPID (CATIA) are being developed at Linköping University. Based on a parametric data definition in XML, this approach allows for a full 3D CAD integration. The one-database approach, also explored by many research organizations, enables the flexible and efficient integration of the different multidisciplinary processes during the whole conceptual design phase. This paper describes the knowledge-based design automated methodology of RAPID, data processing between RAPID and Tango and its application in the courses ‘‘Aircraft conceptual design’’ and ‘‘Aircraft project course’’ at Linköping University. A multifaceted user interface is developed to assist the whole design process."

    Place, publisher, year, edition, pages
    Springer, 2016
    Keyword
    Aircraft conceptual design, Knowledge based, XML database
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-126689 (URN)10.1007/s13272-015-0174-z (DOI)
    Projects
    NFFP5/NFFP6
    Available from: 2016-04-01 Created: 2016-04-01 Last updated: 2017-05-30
    2. Knowledge-based design for future combat aircraft concepts
    Open this publication in new window or tab >>Knowledge-based design for future combat aircraft concepts
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    2014 (English)Conference paper, (Refereed)
    Abstract [en]

    A new fighter aircraft will most likely be acollaborative project. In this study conceptualknowledge-based design is demonstrated, usingmodels of comparable fidelity for sizing, geometrydesign, aerodynamic analysis and system simulationfor aircraft conceptual design. A newgeneration fighter is likely to involve advancedcontrol concept where an assessment of feasibilitythrough simulation is needed already atthe conceptual stage. This co-design leads to adeeper understanding of the trade-offs involved.In this paper a study for a future combat aircraftis made. Conceptual knowledge-based design isdemonstrated by optimizing for a design mission,including a super-cruise segment.

    Place, publisher, year, edition, pages
    St. Peterberg: , 2014
    Keyword
    Conceptual design, Aircraft design, Engine design, Knowledge-based
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-114902 (URN)
    Conference
    29th Congress of the International Council of the Aeronautical Sciences, St. Petersburg, Russia
    Projects
    NFFP5/NFFP6
    Available from: 2015-03-05 Created: 2015-03-05 Last updated: 2017-05-30Bibliographically approved
    3. Knowledge-based future combat aircraft optimization
    Open this publication in new window or tab >>Knowledge-based future combat aircraft optimization
    2016 (English)In: 30th Congress of the International Council of the AeronauticalSciences (ICAS 2016), Bonn: International Council of Aeronautical Sciences (ICAS) , 2016, Vol. 1, 273-280 p.Conference paper, (Refereed)
    Abstract [en]

    Future combat aircraft inherently conceal all the components internally essentially for stealth reasons. The geometry is optimized for subsonic and supersonic flight area distribution and the components and payload to be fitted inside the aircraft. The basic requirements to accomplish are fuel consumption, mission profile, and military performance. Analytical methods comprise of a quick aerodynamic and structural optimization. The result obtained is then compared with multi-fidelity aero-structural analysis

    Place, publisher, year, edition, pages
    Bonn: International Council of Aeronautical Sciences (ICAS), 2016
    Keyword
    Knowledge Based, Combat aircraft, Conceptual Design, Optimization
    National Category
    Aerospace Engineering Vehicle Engineering Applied Mechanics Energy Engineering
    Identifiers
    urn:nbn:se:liu:diva-137644 (URN)978-1-5108-3455-2 (ISBN)
    Conference
    30th Congress of the International Council of the Aeronautical Sciences, Daejeon, South Korea, 25-30 September 2016.
    Projects
    NFFP5/NFFP6
    Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2017-06-02Bibliographically approved
    4. A comprehensive computational multidisciplinary design optimization approach for a tidal power plant turbine
    Open this publication in new window or tab >>A comprehensive computational multidisciplinary design optimization approach for a tidal power plant turbine
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    2017 (English)In: Advances in Mechanical Engineering, ISSN 1687-8132, E-ISSN 1687-8140, Vol. 9, no 3, 1-13 p., 1687814017695174Article in journal (Refereed) Published
    Abstract [en]

    Multidisciplinary design optimization has become a powerful technique to facilitate continuous improvement of complex and multidisciplinary products. Parametric modeling is an essential part with tremendous impact on the flexibility and robustness of multidisciplinary design optimization. This article investigates the effect of relational and non-relational parameterization techniques on the robustness and flexibility of the conceptual design of a multidisciplinary product. Bench marking between relational and non-relational parameterization and their effect on flexibility and robustness indicate that the relational parameterization is an efficient method in the multidisciplinary design optimization process. The inherent properties of the method contribute to an efficient parametric modeling with improved communication between different disciplines. This enhances the performance of the multidisciplinary design optimization process and allows a more flexible and robust design. The considered disciplines are computer-aided design, computational fluid dynamics, finite element analysis, and dynamic simulation. A high-fidelity geometry created in a computer-aided design environment is computer-aided design centric approach and later used in computational fluid dynamics, finite element analysis for a better understanding of the product as it leads to precise outcomes. The proposed approach is implemented for the conceptual design of a novel product, a tidal power plant developed by Minesto AB using a multidisciplinary design optimization process.

    Place, publisher, year, edition, pages
    London: Sage Publications, 2017
    Keyword
    Parametric modeling, conceptual design, computer-aided design, computational fluid dynamics, finite element analysis, dynamic simulation, multidisciplinary design optimization
    National Category
    Aerospace Engineering Production Engineering, Human Work Science and Ergonomics Interaction Technologies
    Identifiers
    urn:nbn:se:liu:diva-137645 (URN)10.1177/1687814017695174 (DOI)000400394500001 ()2-s2.0-85018345706 (Scopus ID)
    Projects
    NFFP5/NFFP6
    Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2017-06-14Bibliographically approved
  • Public defence: 2017-09-01 09:00 Hugo Theorell, ingång 7, Linköping
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Fluorescence Guided Resection of Brain Tumors: Evaluation of a Hand-held Spectroscopic Probe2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Malignant gliomas grow infiltrative in the brain and can therefore not be completely removed by neurosurgical means. However, for an optimized oncological treatment it has proven useful to resect as much as possible of tumor. The identification of the tumor in the marginal zone is difficult but crucial. Studies have shown that visualization of the specific enhancement of 5-aminolevulinic acid(5-ALA) in the tumor can help to maximize the resection. The Department of Biomedical Engineering, Linköping University, has developed an optical hand-held probe (HHP) to identify tumor tissue with a high sensitivity by means of fluorescence spectroscopy.

    The technical design and the optical properties of the probe were gradually developed in a standard neurosurgical setting during resection of malignant gliomas. The device could easily be implemented in the operating room, meeting all requirements in terms of sterile handling and without interference of any kind with other equipment. The integration of the device in a navigation system and its use in combination with a blue light surgical microscope were simple. Measurements in 27 operations during resection of malignant gliomas were compared to results from biopsies from the same tumor locations. The equipment was tested as a stand-alone device (n = 180), integrated in a navigation system or in combination with the blue light microscope (n = 190). A ratiocal culated from the measurements enabled objective and comparable values for different tissue types, in correspondence with the findings from the histopathological examinations and in accordance with the navigation system as well as with the surgical microscope.The marginal zone was explored and tumor fluorescence could be identified beyond the fluorescence as seen through the microscope. A higher sensitivity of the HHP was confirmed; the specificity was lower.

    The combined use of the HHP with a navigation system and with asurgical microscope was beneficial.

    List of papers
    1. Evaluation of a Fiber-Optic Fluorescence Spectroscopy System to Assist Neurosurgical Tumor Resections
    Open this publication in new window or tab >>Evaluation of a Fiber-Optic Fluorescence Spectroscopy System to Assist Neurosurgical Tumor Resections
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    2007 (English)In: Novel Optical Instrumentation for Biomedical Applications III (Proceedings Volume) / [ed] Christian D. Depeursinge, Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2007, Vol. 6631, 66310W-1-66310W-8 p.Conference paper, (Other academic)
    Abstract [en]

    The highly malignant brain tumor, glioblastoma multiforme, is difficult to totally resect without aid due to its infiltrative way of growing and its morphological similarities to surrounding functioning brain under direct vision in the operating field. The need for an inexpensive and robust real-time visualizing system for resection guiding in neurosurgery has been formulated by research groups all over the world. The main goal is to develop a system that helps the neurosurgeon to make decisions during the surgical procedure. A compact fiber optic system using fluorescence spectroscopy has been developed for guiding neurosurgical resections. The system is based on a high power light emitting diode at 395 nm and a spectrometer. A fiber bundle arrangement is used to guide the excitation light and fluorescence light between the instrument and the tissue target. The system is controlled through a computer interface and software package especially developed for the application. This robust and simple instrument has been evaluated in vivo both on healthy skin but also during a neurosurgical resection procedure. Before surgery the patient received orally a low dose of 5-aminolevulinic acid, converted to the fluorescence tumor marker protoporphyrin IX in the malignant cells. Preliminary results indicate that PpIX fluorescence and brain tissue autofluorescence can be recorded with the help of the developed system intraoperatively during resection of glioblastoma multiforme.

    Place, publisher, year, edition, pages
    Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2007
    Series
    Proceedings of SPIE - International Society for Optical Engineering, ISSN 0277-786X ; Vol. 6631
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-38407 (URN)10.1117/12.728546 (DOI)44225 (Local ID)9780819467751 (ISBN)44225 (Archive number)44225 (OAI)
    Conference
    Novel optical instrumentation for biomedical applications III : 17-19 June 2007, Munich, Germany
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-08-16Bibliographically approved
    2. Optical Touch Pointer for Fluorescence Guided Glioblastoma Resection Using 5-Aminolevulinic Acid
    Open this publication in new window or tab >>Optical Touch Pointer for Fluorescence Guided Glioblastoma Resection Using 5-Aminolevulinic Acid
    2010 (English)In: Lasers in Surgery and Medicine, ISSN 0196-8092, E-ISSN 1096-9101, Vol. 42, no 1, 9-14 p.Article in journal (Refereed) Published
    Abstract [en]

    Background and Objective

    Total tumor resection in patients with glioblastoma multiforme (GBM) is difficult to achieve due to the tumor's infiltrative way of growing and morphological similarity to the surrounding functioning brain tissue. The diagnosis is usually subjectively performed using a surgical microscope. The objective of this study was to develop and evaluate a hand-held optical touch pointer using a fluorescence spectroscopy system to quantitatively distinguish healthy from malignant brain tissue intraoperatively.

    Study Design/Materials and Methods

    A fluorescence spectroscopy system with pulsed modulation was designed considering optimum energy delivery to the tissue, minimal photobleaching of PpIX and omission of the ambient light background in the operating room (OR). 5-Aminolevulinic acid (5-ALA) of 5 mg/kg body weight was given to the patients with a presumed GBM prior to surgery. During the surgery a laser pulse at 405 nm was delivered to the tissue. PpIX in glioblastoma tumor cells assigned with peaks at 635 and 704 nm was detected using a fiber optical probe.

    Results/Conclusion

    By using the pulsed fluorescence spectroscopy, PpIX fluorescence is quantitatively detected in the GBM. An effective suppression of low power lamp background from the recorded spectra in addition to a significant reduction of high power surgical lights is achieved.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2010
    Keyword
    background light suppression • fluorescence spectroscopy • glioblastoma multiforme • intraoperative
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-53946 (URN)10.1002/lsm.20868 (DOI)
    Available from: 2010-02-15 Created: 2010-02-15 Last updated: 2017-08-16Bibliographically approved
    3. Fluorescence Spectroscopy Measurements in Ultrasonic Navigated Resection of Malignant Brain Tumors
    Open this publication in new window or tab >>Fluorescence Spectroscopy Measurements in Ultrasonic Navigated Resection of Malignant Brain Tumors
    2011 (English)In: Lasers in Surgery and Medicine, ISSN 0196-8092, E-ISSN 1096-9101, Vol. 43, no 1, 8-14 p.Article in journal (Refereed) Published
    Abstract [en]

    Background and Objective: Glioblastoma multiforme is a highly malignant primary brain tumor. It has no border but at best a marginal zone, however, invisible to the surgeon. An optical touch pointer (OTP) enabling differentiation of healthy and tumor tissue by means of fiber-optic fluorescence spectroscopy has been developed. In combination with an ultrasonic navigation system, the OTP may be used for demarcation of resectable tumor tissue. The aim of the study was to evaluate the clinical performance of OTP during surgery of malignant brain tumors. 

    Study Design/Materials and Methods: Nine patients were operated on with the standard surgical procedure, including white light microscopy and navigation. A total of 5 mg/kg bodyweight of 5-amino-levulin acid was orally administrated before surgery. The OTP was calibrated into the ultrasound-based navigation system and measurements were performed in tumor core and along the tumor border. The ratio between the protoporphyrin IX fluorescence at 635 nm and the autofluorescence was used for quantifications of data. Biopsies (n =20), ultrasound images (n = 30), and visual inspection (n =180) were compared to the fluorescence ratio. 

    Results/Conclusion : Healthy and tumor tissue could be identified and differentiated with the OTP(P < 0.001). The fluorescence ratio in average was 0 outside the tumor and low in the gliotic edema zone around the tumor. It increased in the marginal zone and was highest in the solid tumor tissue. In the necrotic tissue, in the center of the tumor, the ratio in average was 0. The OTP can be used in combination with ultrasound-based navigation and may help to determine whether to resect otherwise not identifiable tissue.

    Keyword
    5-amino-levulin acid (5-ALA);fluorescence-guided resection (FGR);glioblastoma multiforme;optical touch pointer (OTP);protoporphyrin IX (PpIX) fluorescence;ultrasound navigation
    National Category
    Medical Laboratory and Measurements Technologies
    Identifiers
    urn:nbn:se:liu:diva-64689 (URN)10.1002/lsm.21022 (DOI)000286440300002 ()
    Available from: 2011-02-01 Created: 2011-02-01 Last updated: 2017-08-16Bibliographically approved
    4. Combination of Hand-Held Probe and Microscopy for Fluorescence Guided Surgery in the Brain Tumor Marginal Zone
    Open this publication in new window or tab >>Combination of Hand-Held Probe and Microscopy for Fluorescence Guided Surgery in the Brain Tumor Marginal Zone
    2017 (English)In: Photodiagnosis and Photodynamic Therapy, ISSN 1572-1000, Vol. 18, 185-192 p.Article in journal (Refereed) Published
    Abstract [en]

    Background

    Visualization of the tumor is crucial for differentiating malignant tissue from healthy brain during surgery, especially in the tumor marginal zone. The aim of the study was to introduce a fluorescence spectroscopy-based hand-held probe (HHF-probe) for tumor identification in combination with the fluorescence guided resection surgical microscope (FGR-microscope), and evaluate them in terms of diagnostic performance and practical aspects of fluorescence detection.

    Material and Methods

    Eighteen operations were performed on 16 patients with suspected high-grade glioma. The HHF-probe and the FGR-microscope were used for detection of protoporphyrin (PpIX) fluorescence induced by 5-aminolevulinic acid (5-ALA) and evaluated against histopathological analysis and visual grading done through the FGR-microscope by the surgeon. A ratio of PpIX fluorescence intensity to the autofluorescence intensity (fluorescence ratio) was used to quantify the spectra detected by the probe.

    Results

    Fluorescence ratio medians (range 0 – 40) measured by the probe were related to the intensity of the fluorescence in the FGR-microscope, categorized as “none” (0.3, n = 131), “weak” (1.6, n = 34) and “strong” (5.4, n = 28). Of 131 “none” points in the FGR-microscope, 88 (67%) exhibited fluorescence with the HHF-probe. For the tumor marginal zone, the area under the receiver operator characteristics (ROC) curve was 0.49 for the FGR-microscope and 0.65 for the HHF-probe.

    Conclusions

    The probe was integrated in the established routine of tumor resection using the FGR-microscope. The HHF-probe was superior to the FGR-microscope in sensitivity; it detected tumor remnants after debulking under the FGR-microscope. The combination of the HHF-probe and the FGR-microscope was beneficial especially in the tumor marginal zone.

    Place, publisher, year, edition, pages
    Amsterdam: Elsevier, 2017
    Keyword
    High-grade glioma, Fluorescence guided resection (FGR), 5-Aminolaevulinic acid (5-ALA), Fluorescence spectroscopy, Protoporphyrin (PpIX)
    National Category
    Medical Engineering
    Identifiers
    urn:nbn:se:liu:diva-134849 (URN)10.1016/j.pdpdt.2017.01.188 (DOI)000404315000028 ()28223144 (PubMedID)
    Note

    Funding agencies: Swedish Governmental Agency for Innovation Systems (Vinnova); Swedish Foundation for Strategic Research (SSF); Swedish Research Council (VR) [311-2006-7661, 523-2013-2735]; NovaMedTech; Swedish Childhood Cancer Foundation [MT 2013-0043]; ALF Grants Region

    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-08-16Bibliographically approved
  • Public defence: 2017-09-04 10:15 Planck, Fysikhuset, Linköping
    Eriksson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Photoluminescence Characteristics of III-Nitride Quantum Dots and Films2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    III-Nitride semiconductors are very promising in both electronics and optical devices. The ability of the III-Nitride semiconductors as light emitters to span the electromagnetic spectrum from deep ultraviolet light, through the entire visible region, and into the infrared part of the spectrum, is a very important feature, making this material very important in the field of light emitting devices. In fact, the blue emission from Indium Gallium Nitride (InGaN), which was awarded the 2014 Nobel Prize in Physics, is the basis of the common and important white light emitting diode (LED).

    Quantum dots (QDs) have properties that make them very interesting for light emitting devices for a range of different applications, such as the possibility of increasing device efficiency. The spectrally well-defined emission from QDs also allows accurate color reproduction and high-performance communication devices. The small size of QDs, combined with selective area growth allows for an improved display resolution. By control of the polarization direction of QDs, they can be used in more efficient displays as well as in traditional communication devices. The possibility of sending out entangled photon pairs is another QD property of importance for quantum key distribution used for secure communication.

    QDs can hold different exciton complexes, such as the neutral single exciton, consisting of one electron and one hole, and the biexciton, consisting of two excitons. The integrated PL intensity of the biexciton exhibits a quadratic dependence with respect to the excitation power, as compared to the linear power dependence of the neutral single exciton. The lifetime of the neutral exciton is 880 ps, whereas the biexciton, consisting of twice the number of charge carriers and lacks a dark state, has a considerably shorter lifetime of only 500 ps. The ratio of the lifetimes is an indication that the size of the QD is in the order of the exciton Bohr radius of the InGaN crystal making up these QDs in the InGaN QW.

    A large part of the studies of this thesis has been focused on InGaN QDs on top of hexagonal Gallium Nitride (GaN) pyramids, selectively grown by Metal Organic Chemical Vapor Deposition (MOCVD). On top of the GaN pyramids, an InGaN layer and a GaN capping layer were grown. From structural and optical investigations, InGaN QDs have been characterized as growing on (0001) facets on truncated GaN pyramids. These QDs exhibit both narrow photoluminescence linewidths and are linearly polarized in directions following the symmetry of the pyramids.

    In this work, the neutral single exciton, and the more rare negatively charged exciton, have been investigated. At low excitation power, the integrated intensity of the PL peak of the neutral exciton increases linearly with the excitation power. The negatively charged exciton, on the other hand, exhibits a quadratic power dependence, just like that of the biexciton. Upon increasing the temperature, the power dependence of the negatively charged exciton changes to linear, just like the neutral exciton. This change in power dependence is explained in terms of electrons in potential traps close to the QD escaping by thermal excitation, leading to a surplus of electrons in the vicinity of the QD. Consequently, only a single exciton needs to be created by photoexcitation in order to form a negatively charged exciton, while the extra electron is supplied to the QD by thermal excitation.

    Upon a close inspection of the PL of the neutral exciton, a splitting of the peak of just below 0.4 meV is revealed. There is an observed competition in the integrated intensity between these two peaks, similar to that between an exciton and a biexciton. The high energy peak of this split exciton emission is explained in terms of a remotely charged exciton. This exciton state consists of a neutral single exciton in the QD with an extra electron or hole in close vicinity of the QD, which screens the built-in field in the QD.

    The InGaN QDs are very small; estimated to be on the order of the exciton Bohr radius of the InGaN crystal, or even smaller. The lifetimes of the neutral exciton and the negatively charged exciton are approximately 320 ps and 130 ps, respectively. The ratio of the lifetimes supports the claim of the QD size being on the order of the exciton Bohr radius or smaller, as is further supported by power dependence results. Under the assumption of a spherical QD, theoretical calculations predict an emission energy shift of 0.7 meV, for a peak at 3.09 eV, due to the built-in field for a QD with a diameter of 1.3 nm, in agreement with the experimental observations.

    Studying the InGaN QD PL from neutral and charged excitons at elevated temperatures (4 K to 166 K) has revealed that the QDs are surrounded by potential fluctuations that trap charge carriers with an energy of around 20 meV, to be compared with the exciton trapping energy in the QDs of approximately 50 meV. The confinement of electrons close to the QD is predicted to be smaller than for holes, which accounts for the negative charge of the charged exciton, and for the higher probability of capturing free electrons. We have estimated the lifetimes of free electrons and holes in the GaN barrier to be 45 ps and 60 ps, in consistence with excitons forming quickly in the barrier upon photoexcitation and that free electrons and holes get trapped quickly in local potential traps close to the QDs. This analysis also indicates that there is a probability of 35 % to have an electron in the QD between the photoexcitation pulses, in agreement with a lower than quadratic power dependence of the negatively charged exciton.

    InN is an attractive material due to its infrared emission, for applications such as light emitters for communication purposes, but it is more difficult to grow with high quality and low doping concentration as compared to GaN. QDs with a higher In-composition or even pure InN is an interesting prospect as being a route towards increased quantum confinement and room temperature device operation. For all optical devices, p-type doping is needed. Even nominally undoped InN samples tend to be heavily n-type doped, causing problems to make pn-junctions as needed for LEDs. In our work, we present Mg-doped p-type InN films, which when further increasing the Mg-concentration revert to n-type conductivity. We have focused on the effect of the Mg-doping on the light emission properties of these films. The low Mg doped InN film is inhomogeneous and is observed to contain areas with n-type conductivity, so called n-type pockets in the otherwise p-type InN film. A higher concentration of Mg results in a higher crystalline quality and the disappearance of the n-type pockets. The high crystalline quality has enabled us to determine the binding energy of the Mg dopants to 64 meV. Upon further increase of the Mg concentration, the film reverts to ntype conductivity. The highly Mg doped sample also exhibits a red-shifted emission with features that are interpreted as originating from Zinc-Blende inclusions in the Wurtzite InN crystal, acting as quantum wells. The Mg doping is an important factor in controlling the conductivity of InN, as well as its light emission properties, and ultimately construct InN-based devices.

    In summary, in this thesis, both pyramidal InGaN QDs and InGaN QDs in a QW have been investigated. Novel discoveries of exciton complexes in these QD systems have been reported. Knowledge has also been gained about the challenging material InN, including a study of the effect of the Mg-doping concentration on the semiconductor crystalline quality and its light emission properties. The outcome of this thesis enriches the knowledge of the III-Nitride semiconductor community, with the long-term objective to improve the device performance of III-Nitride based light emitting devices.

    List of papers
    1. InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids
    Open this publication in new window or tab >>InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids
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    2012 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 30, 305708- p.Article in journal (Refereed) Published
    Abstract [en]

    Growing InGaN quantum dots (QDs) at the apex of hexagonal GaN pyramids is an elegant approach to achieve a deterministic positioning of QDs. Despite similar synthesis procedures by metal–organic chemical vapor deposition, the optical properties of the QDs reported in the literature vary drastically. The QDs tend to exhibit either narrow or broad emission lines in the micro-photoluminescence spectra. By coupled microstructural and optical investigations, the QDs giving rise to narrow emission lines were concluded to nucleate in association with a (0001) facet at the apex of the GaN pyramid.

    Place, publisher, year, edition, pages
    Institute of Physics (IOP), 2012
    National Category
    Atom and Molecular Physics and Optics
    Identifiers
    urn:nbn:se:liu:diva-79321 (URN)10.1088/0957-4484/23/30/305708 (DOI)000306333500030 ()
    Available from: 2012-07-10 Created: 2012-07-10 Last updated: 2017-08-15Bibliographically approved
    2. Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot
    Open this publication in new window or tab >>Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot
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    2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 6Article in journal (Refereed) Published
    Abstract [en]

    The dynamics of the exciton and the biexciton related emission from a single InGaN quantum dot (QD) have been measured by time-resolved microphotoluminescence spectroscopy. An exciton-biexciton pair of the same QD was identified by the combination of power dependence and polarization-resolved spectroscopy. Moreover, the spectral temperature evolution was utilized in order to distinguish the biexciton from a trion. Both the exciton and the biexciton related emission reveal mono-exponential decays corresponding to time constants of similar to 900 and similar to 500 ps, respectively. The obtained lifetime ratio of similar to 1.8 indicates that the QD is small, with a size comparable to the exciton Bohr radius.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2012
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-84908 (URN)10.1063/1.4742343 (DOI)000307862400022 ()
    Note

    Funding Agencies|Thaksin University in Thailand||Swedish Research Council (VR)||Swedish Foundation for Strategic Research (SSF)||Knut and Alice Wallenberg Foundation||

    Available from: 2012-10-26 Created: 2012-10-26 Last updated: 2017-08-15
    3. The charged exciton in an InGaN quantum dot on a GaN pyramid
    Open this publication in new window or tab >>The charged exciton in an InGaN quantum dot on a GaN pyramid
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    2013 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 1Article in journal (Refereed) Published
    Abstract [en]

    The emission of a charged exciton in an InGaN quantum dot (QD) on top of a GaN pyramid is identified experimentally. The intensity of the charged exciton exhibits the expected competition with that of the single exciton, as observed in temperature-dependent micro-photoluminescence measurements, performed with different excitation energies. The non-zero charge state of this complex is further supported by time resolved micro-photoluminescence measurements, which excludes neutral alternatives of biexciton. The potential fluctuations in the vicinity of the QD that localizes the charge carriers are proposed to be responsible for the unequal supply of electrons and holes into the QD.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2013
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-95961 (URN)10.1063/1.4812984 (DOI)000321497200036 ()
    Note

    Funding Agencies|NANO-N consortium||Swedish Foundation for Strategic Research (SSF)||

    Available from: 2013-08-19 Created: 2013-08-12 Last updated: 2017-08-15
  • Public defence: 2017-09-06 13:15 Ada Lovelace, hus B, Linköping
    Bendtsen, Marcus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Gated Bayesian Networks2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Bayesian networks have grown to become a dominant type of model within the domain of probabilistic graphical models. Not only do they empower users with a graphical means for describing the relationships among random variables, but they also allow for (potentially) fewer parameters to estimate, and enable more efficient inference. The random variables and the relationships among them decide the structure of the directed acyclic graph that represents the Bayesian network. It is the stasis over time of these two components that we question in this thesis.

    By introducing a new type of probabilistic graphical model, which we call gated Bayesian networks, we allow for the variables that we include in our model, and the relationships among them, to change overtime. We introduce algorithms that can learn gated Bayesian networks that use different variables at different times, required due to the process which we are modelling going through distinct phases. We evaluate the efficacy of these algorithms within the domain of algorithmic trading, showing how the learnt gated Bayesian networks can improve upon a passive approach to trading. We also introduce algorithms that detect changes in the relationships among the random variables, allowing us to create a model that consists of several Bayesian networks, thereby revealing changes and the structure by which these changes occur. The resulting models can be used to detect the currently most appropriate Bayesian network, and we show their use in real-world examples from both the domain of sports analytics and finance.

  • Public defence: 2017-09-08 09:30 Hasselquist, Linköping
    Kuruvilla, Jacob
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Proteomics as a multifaceted tool in medicine and environmental assessment2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Proteomics is evolving as a multi-faceted tool for addressing various biochemical and biomedical queries in the field of scientific research. This involves various stages, ranging from sample preparation to data analysis and biological interpretation. Sample preparation involves isolating proteins from the sample source, purifying and digesting them to initiate shotgun proteomics. Shotgun proteomics identifies proteins by bottom-up proteomic approaches where proteins are identified from the fragmentation spectra of their own peptides.

    Paper I: deals with the simplification of functional characterization for nanoparticles intended for use in biomedicine. Proteomics was constructive in differentiating and semi-quantifying the surface of protein corona. This could be beneficial in predicting the interactions between nanoparticles and a biological entity like the cell or a receptor protein and provide initial valuable information related to targeting, uptake and safety.

    Paper II: deals with understanding effects of TiO2 nanoparticles on endothelial cells. A combinatorial approach, involving transcriptomics and proteomics was used to identify aberrations in the permeability and integrity of endothelial cells and tissues. Our study also investigated the correlation of size and how they motivated a differential cellular response. In case of intravenous entry for nanoparticles in targeted drug delivery systems, endothelial cells are the first barrier encountered by these drug carriers. This evaluation involving endothelial cell response could be very instrumental during the designing of NP based drug delivery systems.

    Paper III: Pharmaceuticals and its metabolites could be very hazardous, especially if its disposal is not managed properly. Since water bodies are the ultimate sink, these chemicals could end up there, culminating in toxicity and other ‘mixture effects’ in combination with other factors. To evaluate the effects of the pharmaceutical, propranolol and climatic factors like low salinity conditions, a microcosm exposure was designed and shotgun proteomics helped understand its impact on mussel gills. In this study too, a combination of transcriptomics and proteomics unveiled molecular mechanisms altered in response to stressors, both individually and in combination.

    Paper IV: An interplay of various factors like EBF1 and PAX5 determines B-cell lineage and commitment. This might have been materialized by direct and transient proteinprotein interactions. A unique method called BioID helped screen relevant interactions in living cells by the application of a promiscuous biotin ligase enzyme capable of tagging proteins through biotinylation based on a proximity radius. Biotinylation of endogenous proteins enabled their selective isolation by exploiting the high affinity of biotin and streptavidin on streptavidin coated agarose beads, leading to their identification by mass spectrometry. The biotinylated proteins were potential candidate interactors of EBF1 and PAX5, which were later confirmed by sequencing techniques like ChIP-Seq, ATAC seq, and visualization techniques like proximity ligation assay (PLA).

    List of papers
    1. Surface proteomics on nanoparticles, a step to simplify the rapid prototyping of nanoparticles
    Open this publication in new window or tab >>Surface proteomics on nanoparticles, a step to simplify the rapid prototyping of nanoparticles
    2017 (English)In: Nanoscale Horizons, ISSN 2055-6756, no 1, 55-64 p.Article in journal (Refereed) Published
    Abstract [en]

    Engineered nanoparticles for biomedical applications requireincreasing effectiveness in targeting specific cells while preservingnon-target cell’s safety. We developed a surface proteomicsmethod for a rapid and systematic analysis of the interphasebetween the nanoparticle protein corona and the targeting cellsthat could implement the rapid prototyping of nanomedicines.Native nanoparticles entering in a protein-rich liquid mediaquickly form a macromolecular structure called protein corona.This protein structure defines the physical interaction betweennanoparticles and target cells. The surface proteins compose thefirst line of interaction between this macromolecular structureand the cell surface of a target cell. We demonstrated that SUSTU(SUrface proteomics, Safety, Targeting, Uptake) provides aqualitative and quantitative analysis from the protein coronasurface. With SUSTU, the spatial dynamics of the protein coronasurface can be studied. Data from SUSTU would ascertain thenanoparticle functionalized groups exposed at destiny that couldcircumvent preliminary in vitro experiments. Therefore thismethod could implement the analysis of nanoparticle targetingand uptake capability and could be integrated into a rapidprototyping strategy which is a major challenge in nanomaterialscience. Data are available via ProteomeXchange with identifierPXD004636.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2017
    Keyword
    nanoparticle, protein corona, mass spectrometry, surface proteomics, targeting, rapid prototyping, nanomedicine
    National Category
    Biochemistry and Molecular Biology
    Identifiers
    urn:nbn:se:liu:diva-132406 (URN)10.1039/c6nh00162a (DOI)
    Projects
    Nanoimpact; nanoparticles and rapid prototyping
    Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2017-08-18Bibliographically approved
    2. Shotgun proteomics to unravel marine mussel (Mytilus edulis) response to long-term exposure to low salinity and propranolol in a Baltic Sea microcosm
    Open this publication in new window or tab >>Shotgun proteomics to unravel marine mussel (Mytilus edulis) response to long-term exposure to low salinity and propranolol in a Baltic Sea microcosm
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    2016 (English)In: Journal of Proteomics, ISSN 1874-3919, E-ISSN 1876-7737, Vol. 137, 97-106 p.Article in journal (Refereed) Published
    Abstract [en]

    Pharmaceuticals, among them the β-adrenoreceptor blocker propranolol, are an important group of environmental contaminants reported in European waters. Laboratory exposure to pharmaceuticals on marine species has been performed without considering the input of the ecosystem flow. To unravel the ecosystem response to long-term exposure to propranolol we have performed long-term exposure to propranolol and low salinity in microcosms. We applied shotgun proteomic analysis to gills of Mytilus edulis from those Baltic Sea microcosms and identified 2071 proteins with a proteogenomic strategy. The proteome profiling patterns from the 587 highly reproductive proteins among groups define salinity as a key factor in the mussel´s response to propranolol. Exposure at low salinity drives molecular mechanisms of adaptation based on a decrease in the abundance of several cytoskeletal proteins, signalling and intracellular membrane trafficking pathway combined with a response towards the maintenance of transcription and translation. The exposure to propranolol combined with low salinity modulates the expression of structural proteins including cilia functions and decrease the expression membrane protein transporters. This study reinforces the environment concerns of the impact of low salinity in combination with anthropogenic pollutants and anticipate critical physiological conditions for the survival of the blue mussel in the northern areas.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keyword
    Mytilus edulis, shotgun proteomics, propranolol, low salinity, environmental monitoring, climate change
    National Category
    Biochemistry and Molecular Biology
    Identifiers
    urn:nbn:se:liu:diva-124213 (URN)10.1016/j.jprot.2016.01.010 (DOI)000374368800010 ()
    Funder
    Swedish Research Council
    Note

    Funding agencies: Swedish Research Council-Natural Science; VR-NT; Carl Trygger Foundation; Oscar and Lilli Lamms Minne Foundation; Angpanneforening Research Foundation; Magnus Bergsvall Foundation; IKERBASQUE; Basque Foundation for Science; VINNOVA; County Council of Oste

    Available from: 2016-01-22 Created: 2016-01-22 Last updated: 2017-08-18Bibliographically approved
  • Public defence: 2017-09-08 10:15 Planck, Fysikhuset, Linköping
    Lindmaa, Alexander
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Theoretical prediction of properties of atomistic systems: Density functional theory and machine learning2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The prediction of ground state properties of atomistic systems is of vital importance in technological advances as well as in the physical sciences. Fundamentally, these predictions are based on a quantum-mechanical description of many-electron systems. One of the hitherto most prominent theories for the treatment of such systems is density functional theory (DFT). The main reason for its success is due to its balance of acceptable accuracy with computational efficiency. By now, DFT is applied routinely to compute the properties of atomic, molecular, and solid state systems.

    The general approach to solve the DFT equations is to use a density-functional approximation (DFA). In Kohn-Sham (KS) DFT, DFAs are applied to the unknown exchangecorrelation (xc) energy. In orbital-free DFT on the other hand, where the total energy is minimized directly with respect to the electron density, a DFA applied to the noninteracting kinetic energy is also required. Unfortunately, central DFAs in DFT fail to qualitatively capture many important aspects of electronic systems. Two prime examples are the description of localized electrons, and the description of systems where electronic edges are present.

    In this thesis, I use a model system approach to construct a DFA for the electron localization function (ELF). The very same approach is also taken to study the non-interacting kinetic energy density (KED) in the slowly varying limit of inhomogeneous electron densities, where the effect of electronic edges are effectively included. Apart from the work on model systems, extensions of an exchange energy functional with an improved KS orbital description are presented: a scheme for improving its description of energetics of solids, and a comparison of its description of an essential exact exchange feature known as the derivative discontinuity with numerical data for exact exchange.

    An emerging alternative route towards the prediction of the properties of atomistic systems is machine learning (ML). I present a number of ML methods for the prediction of solid formation energies, with an accuracy that is on par with KS DFT calculations, and with orders-of-magnitude lower computational cost.

    List of papers
    1. Quantum oscillations in the kinetic energy density: Gradient corrections from the Airy gas
    Open this publication in new window or tab >>Quantum oscillations in the kinetic energy density: Gradient corrections from the Airy gas
    2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 7, 075139- p.Article in journal (Refereed) Published
    Abstract [en]

    We derive a closed-form expression for the quantum corrections to the kinetic energy density in the Thomas-Fermi limit of a linear potential model system in three dimensions (the Airy gas). The universality of the expression is tested numerically in a number of three-dimensional model systems: (i) jellium surfaces, (ii) confinement in a hydrogenlike potential (the Bohr atom), (iii) particles confined by a harmonic potential in one and (iv) all three dimensions, and (v) a system with a cosine potential (the Mathieu gas). Our results confirm that the usual gradient expansion of extended Thomas-Fermi theory does not describe the quantum oscillations for systems that incorporate surface regions where the electron density drops off to zero. We find that the correction derived from the Airy gas is universally applicable to relevant spatial regions of systems of types (i), (ii), and (iv), but somewhat surprisingly not (iii). We discuss possible implications of our findings to the development of functionals for the kinetic energy density.

    Place, publisher, year, edition, pages
    American Physical Society, 2014
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-110971 (URN)10.1103/PhysRevB.90.075139 (DOI)000341238200002 ()
    Note

    Funding Agencies|Swedish Research Council (VR) [621-2011-4249]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials (LiLi-NFM) - VR; U.S. Department of Energys National Nuclear Security Administration [DE-AC04-94AL85000]

    Available from: 2014-10-02 Created: 2014-10-01 Last updated: 2017-08-15
    2. Energetics of the AK13 semilocal Kohn-Sham exchange energy functional
    Open this publication in new window or tab >>Energetics of the AK13 semilocal Kohn-Sham exchange energy functional
    2016 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 94, no 15, 155143Article in journal (Refereed) Published
    Abstract [en]

    The recent nonempirical semilocal exchange functional of Armiento and Kummel [Phys. Rev. Lett. 111, 036402 (2013)], AK13, incorporates a number of features reproduced by higher-order theory. The AK13 potential behaves analogously with the discontinuous jump associated with the derivative discontinuity at integer particle numbers. Recent works have established that AK13 gives a qualitatively improved orbital description compared to other semilocal methods, and reproduces a band structure closer to higher-order theory. However, its energies and energetics are inaccurate. The present work further investigates the deficiency in energetics. In addition to AK13 results, we find that applying the local-density approximation (LDA) non-self-consistently on the converged AK13 density gives very reasonable energetics with equilibrium lattice constants and bulk moduli well described across 13 systems. We also confirm that the attractive orbital features of AK13 are retained even after full structural relaxation. Hence, the deficient energetics cannot be a result of the AK13 orbitals having adversely affected the quality of the electron density compared to that of usual semilocal functionals; an improved orbital description and good energetics are not in opposition. This is also confirmed by direct calculation of the principal component of the electric field gradient. In addition, we prove that the non-self-consistent scheme is equivalent to using a single external-potential-dependent functional in an otherwise consistent, nonvariational Kohn-Sham density-functional theory (KS DFT) scheme. Furthermore, our results also demonstrate that, while an internally consistent KS functional is presently missing, non-self-consistent LDA on AK13 orbitals works as a practical nonempirical computational scheme to predict geometries, bulk moduli, while retaining the band structure features of AK13 at the computational cost of semi-local DFT.

    Place, publisher, year, edition, pages
    AMER PHYSICAL SOC, 2016
    National Category
    Theoretical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-133756 (URN)10.1103/PhysRevB.94.155143 (DOI)000390031400002 ()
    Note

    Funding Agencies|Swedish Research Council (VR) [621-2011-4249]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials (LiLi-NFM) - VR; Swedish e-Science Research Centre (SeRC)

    Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2017-08-15
    3. Crystal structure representations for machine learning models of formation energies
    Open this publication in new window or tab >>Crystal structure representations for machine learning models of formation energies
    2015 (English)In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 115, no 16, 1094-1101 p.Article in journal (Refereed) Published
    Abstract [en]

    We introduce and evaluate a set of feature vector representations of crystal structures for machine learning (ML) models of formation energies of solids. ML models of atomization energies of organic molecules have been successful using a Coulomb matrix representation of the molecule. We consider three ways to generalize such representations to periodic systems: (i) a matrix where each element is related to the Ewald sum of the electrostatic interaction between two different atoms in the unit cell repeated over the lattice; (ii) an extended Coulomb-like matrix that takes into account a number of neighboring unit cells; and (iii) an ansatz that mimics the periodicity and the basic features of the elements in the Ewald sum matrix using a sine function of the crystal coordinates of the atoms. The representations are compared for a Laplacian kernel with Manhattan norm, trained to reproduce formation energies using a dataset of 3938 crystal structures obtained from the Materials Project. For training sets consisting of 3000 crystals, the generalization error in predicting formation energies of new structures corresponds to (i) 0.49, (ii) 0.64, and (iii) 0.37eV/atom for the respective representations.

    Place, publisher, year, edition, pages
    Wiley, 2015
    Keyword
    machine learning; formation energies; representations; crystal structure; periodic systems
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-120326 (URN)10.1002/qua.24917 (DOI)000357606000010 ()
    Note

    Funding Agencies|Swedish Research Council (VR) [621-2011-4249]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials - VR; Swiss National Science foundation [PP00P2_138932]; Office of Science of the U.S. DOE [DE-AC02-06CH11357]; Air Force Office of Scientific Research, Air Force Material Command, USAF [FA9550-15-1-0026]

    Available from: 2015-07-31 Created: 2015-07-31 Last updated: 2017-08-15
    4. Machine Learning Energies of 2 Million Elpasolite (AB2D6) Crystals
    Open this publication in new window or tab >>Machine Learning Energies of 2 Million Elpasolite (AB2D6) Crystals
    2016 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, ISSN 031-9007, Vol. 117, no 13, 135502Article in journal (Refereed) Published
    Abstract [en]

    Elpasolite is the predominant quaternary crystal structure (AlNaK2F6 prototype) reported in the Inorganic Crystal Structure Database. We develop a machine learning model to calculate density functional theory quality formation energies of all ∼2×106 pristine ABC2D6 elpasolite crystals that can be made up from main-group elements (up to bismuth). Our model’s accuracy can be improved systematically, reaching a mean absolute error of 0.1  eV/atom for a training set consisting of 10×103 crystals. Important bonding trends are revealed: fluoride is best suited to fit the coordination of the D site, which lowers the formation energy whereas the opposite is found for carbon. The bonding contribution of the elements A and B is very small on average. Low formation energies result from A and B being late elements from group II, C being a late (group I) element, and D being fluoride. Out of 2×106 crystals, 90 unique structures are predicted to be on the convex hull—among which is NFAl2Ca6, with a peculiar stoichiometry and a negative atomic oxidation state for Al.

    Place, publisher, year, edition, pages
    American Physical Society, 2016
    Keyword
    Machine learning, AI, Elpasolite, Materials
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-131473 (URN)10.1103/PhysRevLett.117.135502 (DOI)000383849400010 ()
    Funder
    Swedish Research Council, 621-2011-4249,
    Note

    Funding agencies: Swiss National Science Foundation [PP00P2_138932]; Air Force Office of Scientific Research, Air Force Material Command, USAF [FA9550-15-1-0026]; NCCR MARVEL - Swiss National Science Foundation; Swiss National Supercomputing Centre (CSCS) [mr14]; Swedish R

    Available from: 2016-09-22 Created: 2016-09-22 Last updated: 2017-08-15Bibliographically approved
  • Public defence: 2017-09-12 13:15 K3, Norrköping
    Steins, Krisjanis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Towards Increased Use of Discrete-Event Simulation for Hospital Resource Planning2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Health care systems in many countries are experiencing a growing demand while their resources remain limited. The discrepancy between demand and capacity creates many problems – long waiting times for treatment, overcrowding in hospital wards, high workload, etc. More efficient delivery of health care services can be achieved by better planning of its resources so that the mismatch between demand and capacity is minimized. Planning health care resources, including hospital resources, is difficult due to system complexity and variability in both resource availability and demand. Discrete-event simulation and other operational research methods can be used for solving planning problems in health care, and have been gaining increased attention from researchers during recent decades. Despite the growing number of academic publications, simulation appears to be less used in health care than in other application areas and only a small proportion of simulation studies is actually implemented.

    The aim of this thesis is to contribute to increased use of discrete-event simulation in hospital resource planning. The separate studies regarding intensive care unit capacity planning, operating room allocation strategies and the management of emergency patient flow in a radiology department highlight both the possibilities and the requirements for practical application of discrete-event simulation in hospital resource planning. The studies are described in five papers.

    In the first paper, the relationship between intensive care unit (ICU) occupancy and patient outcomes was investigated and the results showed that risk adjusted mortality was higher in the group of patients who were treated during high levels of occupancy. This indicates that appropriate planning of ICU resources is necessary to avoid adverse effects on patient outcomes.

    In the second paper, analysis of a relatively simple care chain consisting of two hospital departments – emergency and radiology – revealed a process that was not very well defined and measured. Investigation into data availability uncovered disparate information systems storing incompatible and fragmented data. It suggests that the current degree of process orientation and the current IT infrastructure does not enable efficient use of quantitative process analysis and management tools such as simulation.

    In the third paper, the value and possibilities of using simulation modelling in hospital resource planning were examined through the development and use of a simulation model for improved operating room time allocation and patient flow in a hospital operating department. The model was initially used for studying overcrowding in a post-anaesthesia care unit. Advanced planning logic implemented in the model enabled evaluation of several different scenarios aiming to improve the utilization of operating room resources. The results showed that it is possible to achieve slightly better and more even resource utilization, as well as provide greater flexibility in scheduling operations.

    In the fourth paper, a generic ICU model was developed and validated using data from four different hospital ICUs. The model was adapted and calibrated stepwise in order to identify important parameters and their values to obtain a match between model predictions and actual data. The study showed that in presence of high quality data and well defined process logic it is possible to develop a generic ICU simulation model that could provide accurate decision support for planning critical care resources.

    In the fifth paper, a number of factors that can contribute to successful implementation of simulation results in health care were identified. The timing of the simulation study must be right to support a critical decision, the benefit from implementation should clearly outweigh the cost of making the necessary changes and the model should be thoroughly validated to increase the credibility of the results. Staff involvement in simulation modelling activities, availability of good quality data, as well as proper incentives to improve the system contribute to implementation as well. These findings can help in establishing the conditions for successful implementation in future applications of simulation modelling in health care.

    List of papers
    1. A modern process perspective, process mapping, and simulation in health care: Opportunities and IT infrastructural needs
    Open this publication in new window or tab >>A modern process perspective, process mapping, and simulation in health care: Opportunities and IT infrastructural needs
    2010 (English)In: Proceedings of 2010 IEEE Workshop on Health Care Management (WHCM), 2010, 1-6 p.Conference paper, (Refereed)
    Abstract [en]

    Today, health care organizations often claim that theyare “process oriented”, and that one should approach health carefrom a process perspective in order to utilize the present ITrelated benefits; such as increased service quality, cost efficiency,and enhanced communication. In this paper we investigate howwell founded the concept of process orientation really is – byexamining IT/IS infrastructures, and procedures for processdefinition, visualization, and evaluation – at a prominent hospitalin Stockholm, Sweden. A case study of the organization and theinteraction of the emergency and radiology departments at thesame hospital (using process mapping and data analysis) revealsdata fragmentation, incompatible data, and disparateinformation systems. This results in difficulties regarding processdefinition and analysis, which makes the use of innovative toolssuch as simulation, problematic. The implications of this, and thecontextual factors, are also discussed and some finalrecommendations for smooth digitization are put forth.Today, health care organizations often claim that theyare “process oriented”, and that one should approach health carefrom a process perspective in order to utilize the present ITrelated benefits; such as increased service quality, cost efficiency,and enhanced communication. In this paper we investigate howwell founded the concept of process orientation really is – byexamining IT/IS infrastructures, and procedures for processdefinition, visualization, and evaluation – at a prominent hospitalin Stockholm, Sweden. A case study of the organization and theinteraction of the emergency and radiology departments at thesame hospital (using process mapping and data analysis) revealsdata fragmentation, incompatible data, and disparateinformation systems. This results in difficulties regarding processdefinition and analysis, which makes the use of innovative toolssuch as simulation, problematic. The implications of this, and thecontextual factors, are also discussed and some finalrecommendations for smooth digitization are put forth.

    Keyword
    IT, digitization, process mapping, process orientation, data analysis, discrete event simulation (DES), health care.
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-56553 (URN)10.1109/WHCM.2010.5441276 (DOI)978-1-4244-4998-9 (ISBN)978-1-4244-4997-2 (ISBN)
    Conference
    IEEE Workshop on Health Care Management, February 18-20, Venice, Italy
    Available from: 2010-05-21 Created: 2010-05-21 Last updated: 2017-08-14
    2. Increasing Utilization in a Hospital Operating Department Using Simulation Modeling
    Open this publication in new window or tab >>Increasing Utilization in a Hospital Operating Department Using Simulation Modeling
    2010 (English)In: Simulation (San Diego, Calif.), ISSN 0037-5497, E-ISSN 1741-3133, Vol. 86, no 8-9, 463-480 p.Article in journal (Refereed) Published
    Abstract [en]

    This article focuses on the planning and scheduling of operating rooms (ORs) in a regional hospital in Sweden. A simulation study was carried out to find new ideas and new planning and scheduling techniques to improve the overall process of surgery, including pre- and post-operating activities. This study mainly addresses the problem of low utilization of the ORs, and also takes into consideration problems with variation in workload, both in ORs and in post-anesthesia care units. The final simulation model includes pre-operative care carried out in the operating department and all ORs, as well as post-operative care units. It was driven by a number of input parameters, such as the volume and specific characteristics of actual cases, opening hours and number of ORs, and the number of beds for pre- and post-operative care. The model also includes logic for prioritizing and allocating cases to available ORs, planning operating schedules and the utilization of medical equipment limited in quantity. Output performance measures from simulation experiments include the utilization of allocated OR times, waiting time for patients, queue dynamics, number of cancellations, and variation of finishing times, as well as occupancy statistics in the post-operative care unit. Four different change alternatives were evaluated using the simulation model. Simulation experiments showed that with the implementation of the proposed changes it is possible to achieve slightly better and more even resource utilization, as well as provide greater flexibility in scheduling operations.

    Place, publisher, year, edition, pages
    SAGE, 2010
    Keyword
    Healthcare, operating department, operating rooms, utilization, discrete-event simulation, planning, scheduling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-56554 (URN)10.1177/0037549709359355 (DOI)000280765600002 ()
    Available from: 2010-05-21 Created: 2010-05-21 Last updated: 2017-08-14
    3. A generic simulation model for planning critical care resource requirements
    Open this publication in new window or tab >>A generic simulation model for planning critical care resource requirements
    2013 (English)In: Anaesthesia, ISSN 0003-2409, E-ISSN 1365-2044, Vol. 68, no 11, 1148-1155 p.Article in journal (Refereed) Published
    Abstract [en]

    Intensive care capacity planning based on factual or forecasted mean admission numbers and mean length of stay without taking non-linearity and variability into account is fraught with error. Simulation modelling may allow for a more accurate assessment of capacity needs. We developed a generic intensive care simulation model using data generated from anonymised patient records of all admissions to four different hospital intensive care units. The model was modified and calibrated stepwise to identify important parameters and their values to obtain a match between model predictions and actual data. The most important characteristic of the final model was the dependency of admission rate on actual occupancy. Occupancy, coverage and transfers of the final model were found to be within 2% of the actual data for all four simulated intensive care units. We have shown that this model could provide accurate decision support for planning critical care resource requirements.

    National Category
    Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:liu:diva-102514 (URN)10.1111/anae.12408 (DOI)
    Available from: 2013-12-12 Created: 2013-12-12 Last updated: 2017-08-14
    4. Identifying Factors for Successful Implementation of Simulation Modeling in Healthcare
    Open this publication in new window or tab >>Identifying Factors for Successful Implementation of Simulation Modeling in Healthcare
    2015 (English)In: International Journal of Privacy and Health Information Management (IJPHIM), ISSN 2155-5621, Vol. 3, no 1, 1-19 p.Article in journal (Refereed) Published
    Abstract [en]

    A number of academic literature surveys have shown that only a small fraction of published healthcare simulation studies are actually implemented. This research identifies factors that can contribute to successful implementation of simulation results in healthcare. The authors have been involved in a six year long simulation study in a Swedish regional hospital’s operating department. The three most important factors that contributed to implementation in this case were: the timing of simulation study to support a critical decision, advantageous cost benefit ratio of the implementation and thorough model validation. Other contributing factors included high degree of staff involvement, availability of good quality data, as well as proper incentives to improve the system. Findings of this study can help in establishing the prerequisites for successful implementation in other cases.

    Place, publisher, year, edition, pages
    IGI Global, 2015
    Keyword
    Healthcare Simulation, Implementation, Operating Room Planning, Simulation Quality, Success Factors
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-137892 (URN)10.4018/IJPHIM.2015010101 (DOI)
    Available from: 2017-05-31 Created: 2017-05-31 Last updated: 2017-08-14
  • Public defence: 2017-09-15 09:00 Berzeliussalen, Linköping
    Aziz, Abdul Maruf Asif
    Linköping University, Department of Clinical and Experimental Medicine, Center for Social and Affective Neuroscience. Linköping University, Faculty of Medicine and Health Sciences.
    Neuropeptide Receptors as Treatment Targets in Alcohol Use Disorders2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Alcohol use disorder (AUD) is a complex disorder with multiple pathophysiological processes contributing to the initiation, progression and development of the disease state. AUD is a chronic relapsing disease with escalation of alcohol-intake over time in repeated cycles of tolerance, abstinence and relapse and hence, it is very difficult to treat. There are only a few currently available treatments with narrow efficacy and variable patient response. Thus it is important to find new, more effective medications to increase the number of patients who can benefit from pharmacological treatment of AUD.

    The research presented in this thesis work focuses on the critical involvement of central neuropeptides in alcohol-related behaviors. The overall aim was to evaluate the nociceptin/orphanin FQ (NOP) receptor, the neuropeptide Y (NPY) Y2 receptor and the melanin-concentrating hormone (MCH) receptor 1 as novel and potential pharmacological treatment targets for AUD by testing the NOP receptor agonist SR-8993, the NPY-Y2 receptor antagonist CYM-9840 and the MCH1 receptor antagonist GW803430 in established animal models.

    In the first study (Paper I), the novel and selective NOP agonist SR-8993 was assessed in rat models of motivation to obtain alcohol and relapse to alcohol seeking behavior using the operant self-administration (SA) paradigm. Firstly, treatment with SR-8993 (1 mg/kg) showed a mildly anxiolytic effect and reversed acute alcohol withdrawal-induced “hangover” anxiety in the elevated plus-maze (EPM). Next, it potently attenuated alcohol SA and motivation to obtain alcohol in the progressive ratio responding (PRR) and reduced both alcohol cue-induced and yohimbine stress-induced reinstatement of alcohol seeking, without affecting the pharmacology and metabolism of alcohol nor other control behaviors. To extend these findings, SR-8993 was evaluated in escalated alcohol-intake in rats.  Treatment with SR-8993 significantly suppressed alcohol-intake and preference in rats that were trained to consume high amounts of alcohol in the two-bottle free choice intermittent access (IA) paradigm. SR-8993 also blocked operant SA of alcohol in rats that showed robust escalation in operant alcohol SA following chronic IA exposure to alcohol.

    In the second study (Paper II), SR-8993 was further evaluated in a model for escalated alcohol-intake induced by long-term IA exposure to alcohol. The effect of previous experience on operant alcohol SA on two-bottle free choice preference drinking was evaluated and sensitivity to treatment with SR-8993 was tested in rats selected for escalated and non-escalated alcohol seeking behavior. We found that rats exposed to the combined SA-IA paradigm showed greater sensitivity to SR-8993 treatment. In addition, acute escalation of alcohol SA after a three-week period of abstinence was completely abolished by pretreatment with SR-8993.

    In the third study (Paper III), the effects of the novel, small molecule NPY-Y2 antagonist CYM-9840 were tested in operant alcohol SA, PRR which is a model for motivation to work for alcohol and reinstatement of alcohol-seeking behavior. Treatment with CYM-9840 (10 mg/kg) potently attenuated alcohol SA, progressive ratio responding and stress-induced reinstatement using yohimbine as the stressor, while alcohol cue-induced reinstatement was unaffected. Moreover, a range of control behaviors including taste sensitivity, locomotor and pharmacological sensitivity to the sedative effects of alcohol remained unaffected by CYM-9840 pretreatment, indicating that its effects are specific to the rewarding and motivational aspects of alcohol-intake and related behaviors. CYM-9840 also reversed acute alcohol withdrawal-induced “hangover” anxiety measured in the EPM and reduced alcohol-intake in the 4 hour limited access two-bottle free choice preference drinking model.

    Finally, in the fourth study (Paper IV), the selective MCH1-R antagonist GW803430 was tested in rat models of escalated alcohol-intake. Pretreatment with GW803430 (effective at 10 & 30 mg/kg) dose-dependently reduced alcohol and food-intake in rats that consumed high amounts of alcohol during IA, while it only decreased food-intake in rats that consumed low amounts of alcohol during IA, likely due to a floor effect. Upon protracted abstinence following IA, GW803430 significantly reduced operant alcohol SA and this was associated with adaptations in MCH and MCH1-R gene-expression. In contrast, GW803430 did not affect escalated alcohol SA induced by chronic alcohol vapor exposure and this was accompanied by no change in MCH or MCH1-R gene expression. Overall, these results suggest that the MCH1-R antagonist affects alcohol-intake through regulation of both motivation for caloric-intake and the rewarding properties of alcohol.

    In conclusion, our results suggest critical roles for these central neuropeptides in the regulation of anxiety and of alcohol reward, making them potential pharmacological targets in the treatment of AUD.

    List of papers
    1. The nociceptin/orphanin FQ receptor agonist SR-8993 as a candidate therapeutic for alcohol use disorders: validation in rat models
    Open this publication in new window or tab >>The nociceptin/orphanin FQ receptor agonist SR-8993 as a candidate therapeutic for alcohol use disorders: validation in rat models
    Show others...
    2016 (English)In: Psychopharmacology, ISSN 0033-3158, E-ISSN 1432-2072, Vol. 233, no 19-20, 3553-3563 p.Article in journal (Refereed) Published
    Abstract [en]

    RATIONALE: Alcoholism is a complex disorder in which diverse pathophysiological processes contribute to initiation and progression, resulting in a high degree of heterogeneity among patients. Few pharmacotherapies are presently available, and patient responses to these are variable. The nociceptin/orphanin FQ (NOP) receptor has been suggested to play a role both in alcohol reward and in negatively reinforced alcohol seeking. Previous studies have shown that NOP-receptor activation reduces alcohol intake in genetically selected alcohol-preferring as well as alcohol-dependent rats. NOP activation also blocks stress- and cue-induced reinstatement of alcohol-seeking behavior.

    OBJECTIVES: Here, we aimed to examine a novel, potent, and brain-penetrant small-molecule NOP-receptor agonist, SR-8993, in animal models of alcohol- as well as anxiety-related behavior using male Wistar rats.

    RESULTS: SR-8993 was mildly anxiolytic when given to naïve animals and potently reversed acute alcohol withdrawal-induced ("hangover") anxiety. SR-8993 reduced both home-cage limited access drinking, operant responding for alcohol, and escalation induced through prolonged intermittent access to alcohol. SR-8993 further attenuated stress- as well as cue-induced relapse to alcohol seeking. For the effective dose (1.0 mg/kg), non-specific effects such as sedation may be limited, since a range of control behaviors were unaffected, and this dose did not interact with alcohol elimination.

    CONCLUSION: These findings provide further support for NOP-receptor agonism as a promising candidate treatment for alcoholism and establish SR-8993 or related molecules as suitable for further development as therapeutics.

    Place, publisher, year, edition, pages
    Springer, 2016
    Keyword
    Nociception/orphanin FQ, Agonist, Wistar rat, Alcohol, Operant, Reinstatement, Elevated plus-maze
    National Category
    Substance Abuse
    Identifiers
    urn:nbn:se:liu:diva-132347 (URN)10.1007/s00213-016-4385-8 (DOI)000383672500006 ()27515665 (PubMedID)
    Note

    Funding Agencies|National Institutes of Health [R01-DA035055]; Swedish Research Council [2010-3219]

    Available from: 2016-11-12 Created: 2016-11-01 Last updated: 2017-08-21Bibliographically approved
    2. Melanin-Concentrating Hormone and Its MCH-1 Receptor: Relationship Between Effects on Alcohol and Caloric Intake
    Open this publication in new window or tab >>Melanin-Concentrating Hormone and Its MCH-1 Receptor: Relationship Between Effects on Alcohol and Caloric Intake
    Show others...
    2016 (English)In: Alcoholism: Clinical and Experimental Research, ISSN 0145-6008, E-ISSN 1530-0277, Vol. 40, no 10, 2199-2207 p.Article in journal (Refereed) Published
    Abstract [en]

    Background: Reward and energy homeostasis are both regulated by a network of hypothalamic neuropeptide systems. The melanin-concentrating hormone (MCH) and its MCH-1 receptor (MCH1-R) modulate alcohol intake, but it remains unknown to what extent this reflects actions on energy balance or reward. Here, we evaluated the MCH1-R in regulation of caloric intake and motivation to consume alcohol in states of escalated consumption.

    Methods: Rats had intermittent access (IA) to alcohol and were divided into high- and low-drinking groups. Food and alcohol consumption was assessed after administration of an MCH1-R antagonist, GW803430. Next, GW803430 was evaluated on alcohol self-administration in protracted abstinence induced by IA in high-drinking rats. Finally, the effect of GW803430 was assessed on alcohol self-administration in acute withdrawal in rats exposed to alcohol vapor. Gene expression of MCH and MCH1-R was measured in the hypothalamus and nucleus accumbens (NAc) in both acute and protracted abstinence.

    Results: High-drinking IA rats consumed more calories from alcohol than chow and GW803430 decreased both chow and alcohol intake. In low-drinking rats, only food intake was affected. In protracted abstinence from IA, alcohol self-administration was significantly reduced by pretreatment with GW803430 and gene expression of both MCH and the MCH1-R were dysregulated in hypothalamus and NAc. In contrast, during acute withdrawal from vapor exposure, treatment with GW803430 did not affect alcohol self-administration, and no changes in MCH or MCH1-R gene expression were observed.

    Conclusions: Our data suggest a dual role of MCH and the MCH1-R in regulation of alcohol intake, possibly through mechanisms involving caloric intake and reward motivation. A selective suppression of alcohol self-administration during protracted abstinence by GW803430 was observed and accompanied by adaptations in gene expression of MCH and MCH1-R. Selective suppression of escalated consumption renders the MCH1-R an attractive target for treatment of alcohol use disorders.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2016
    Keyword
    Alcohol Escalation, Reward, Motivation, Calorie Intake, Melanin-Concentrating Hormone Receptor-1
    National Category
    Substance Abuse
    Identifiers
    urn:nbn:se:liu:diva-132522 (URN)10.1111/acer.13181 (DOI)000385542900017 ()27579857 (PubMedID)
    Available from: 2016-11-14 Created: 2016-11-13 Last updated: 2017-08-21Bibliographically approved
  • Public defence: 2017-09-15 10:00 Key 1, Key-huset, Linköping
    Avdan, Nazlı
    Linköping University, Department of Culture and Communication, Language and Culture. Linköping University, Faculty of Arts and Sciences.
    ‘Collaborative Competition’: Stance-taking and Positioning in the European Parliament2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The European Parliament (EP) is the scene where certain issues concerning over 500 million ‘Europeans’ are publicly debated and where politically relevant groupings are discursively coconstructed. While the Members of the Parliament (MEPs) pursue their political agendas, intergroup boundaries are drawn, reinforced, and/or transgressed. Speakers constantly take stances on behalf of groupings in relation to some presupposed other groupings and argue what differentiates ‘Self’ from ‘Others’. This study examines patterns of language use by the MEPs as they engage in the contextually and historically situated dialogical processes of intergroup positioning and stance-taking. It further focuses on the strategic and competitive activities of grouping, grounding, and alignment in order to reveal the dynamic construction of intergroup boundaries.

    The study is based on a collection of Blue-card question-answer sequences from the plenary debates held at the EP in 2011, when the Sovereign Debt Crisis had been stabilized to some degree but still evoked plenty of controversy.

    Theoretically the study builds on Stance Theory (Du Bois, 2007), Positioning Theory (Davies & Harré, 1990), and several broadly social constructivist approaches to discourse analysis (Fairclough, 1995).

    The analysis shows that intergroup positioning in the EP emerges as what I call a ‘collaborative competition’ between contradictory ideologies and political agendas. The MEPs strategically manipulate their opponents' prior or projected utterances in order to set up positions for self, a grouping he or she stands for, and thereby its adversaries. All participants engage in the maintenance and negotiation of intergroup boundaries, even though the boundaries hardly ever coincide between the different speakers. They discursively fence off some imaginary territories, leaving their adversaries with vague positions.

    When asking Blue-card questions, the MEPs use a particular turn organization, which involves routine forms of interactional units, namely addressing, question framing and question forms, each of which is shown to contribute to stance-taking. A dynamic model of stance-taking is suggested, allowing for a fluid transformation of the stance object as well as the discursively constructed stance-takers.

    While Blue-card questions are meant to serve as a structured procedure for eliciting information from a speaker, the analysis demonstrates that the MEPs accomplish various divergent actions that serve intergroup positioning. The dissertation thus contributes to the understanding of the discursive games played in the EP as the MEPs strive to construct social realities that fit their political ends.

  • Public defence: 2017-09-15 10:15 Planck, Fysikhuset, Linköping
    Bengtsson, Katarina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Electrokinetic devices from polymeric materials2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are multiple applications for polymers: our bodies are built of them, plastic bags and boxes used for storage are composed of them, as are the shells for electronics, TVs, computers, clothes etc. Many polymers are cheap, and easy to manufacture and process which make them suitable for disposable systems. The choice of polymer to construct an object will therefore highly influence the properties of the object itself. The focus of this thesis is the application of commonly used polymers to solve some challenges regarding integration of electrodes in electrokinetic devices and 3D printing.

    The first part of this thesis regards electrokinetic systems and the electrodes’ impact on the system. Electrokinetic systems require Faradaic (electrochemical) reactions at the electrodes to maintain an electric field in an electrolyte. The electrochemical reactions at the electrodes allow electron-to-ion transduction at the electrode-electrolyte interface, necessary to drive a current at the applied potential through the system, which thereby either cause flow (electroosmosis) or separation (electrophoresis). These electrochemical reactions at the electrodes, such as water electrolysis, are usually problematic in analytical systems and systems applied in biology. One solution to reduce the impact of water electrolysis is by replacing metal electrodes with electrochemically active polymers, e.g. poly(3,4-ethylenedioxythiophene) (PEDOT). Paper 1 demonstrates that PEDOT electrodes can replace platinum electrodes in a gel electrophoretic setup. Paper 2 reports an all-plastic, planar, flexible electroosmotic pump which continuously transports water from one side to the other using potentials as low as 0.3 V. This electroosmotic pump was further developed in paper 3, where it was made into a compact and modular setup, compatible with commercial microfluidic devices. We demonstrated that the pump could maintain an alternating flow for at least 96 h, with a sufficient flow of cell medium to keep cells alive for the same period of time.

    The second part of the thesis describes the use of 3D printers for manufacturing prototypes and the material requirements for 3D printing. Protruding and over-hanging structures are more challenging to print using a 3D printer and usually require supporting material during the printing process. In paper 4, we showed that polyethylene glycol (PEG), in combination with a carbonate-based plasticizer, functions well as a 3D printable sacrificial template material. PEG2000 with between 20 and 30 wt% dimethyl carbonate or propylene carbonate have good shear-thinning rheology, mechanical and chemical stability, and water solubility, which are advantageous for a supporting material used in 3D printing.

    The advances presented in this thesis have solved some of the challenges regarding electrokinetic systems and prototype manufacturing. Hopefully this will contribute to the development of robust, disposable, low-cost, and autonomous electrokinetic devices.

    List of papers
    1. Conducting Polymer Electrodes for Gel Electrophoresis
    Open this publication in new window or tab >>Conducting Polymer Electrodes for Gel Electrophoresis
    2014 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 9, no 2, 0089416- p.Article in journal (Refereed) Published
    Abstract [en]

    In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that p-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

    Place, publisher, year, edition, pages
    Public Library of Science, 2014
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-105901 (URN)10.1371/journal.pone.0089416 (DOI)000331711900141 ()
    Available from: 2014-04-14 Created: 2014-04-12 Last updated: 2017-08-18Bibliographically approved
  • Public defence: 2017-09-15 10:26 Schrödinger, Fysikhuset, Linköping
    Qian, Deping
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Studies of Voltage Losses in Organic Solar Cells2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organic photovoltaic (OPV) devices based on semiconducting polymers and small molecules are potential alternatives to inorganic solar cells, owing to their advantages of being inexpensive, lightweight, flexible and suitable for roll-to-roll production. The state of art organic solar cells (OSCs) performed power conversion efficiencies (PCEs) over 13%.

    The quantum efficiency losses in OSCs have been significantly reduced within the charge generation and extraction processes, resulting in high EQEPV (70-90%) and high FF (70-80%). Whereas, large voltage losses (Δ𝑉 = 𝐸𝑔/𝑞 − 𝑉𝑂𝐶) were observed in conventional fullerene based solar cells, and it has been the main limiting factor for further OPV advancement. Therefore, strategies to reduce the voltage losses are required.

    In this thesis, newly designed non-fullerene (NF) acceptors are used to construct novel material systems for high efficiency solar cells. In particular, we studied the hole transfer in these fullerene free systems. We also reported a NF system that exhibit ultrafast and efficient charge separation despite a negligible driving force, as ECT is nearly identical to 𝐸𝑔. Moreover, the small driving force is found to have minimal detrimental effects on charge transfer dynamics of the OSCs. We demonstrate a NF based OSC with efficiency of 9.5% and internal quantum efficiency nearly 90% despite a low voltage loss of 0.61 V. This creates a path towards highly efficient OSCs with a low voltage loss.

    CT states in OSCs are also investigated, since VOC is governed by the CT energy (ECT), which is found as 𝑞𝑉𝑂𝐶 = 𝐸𝐶𝑇 − 0.6 in a large set of fullerene based solar cells. In order to reduce these recombination losses from CT states, we explored polymer-diPDI systems which exhibited weakened D-A coupling strength, due to the steric hindrance effect. The radiative recombination losses at D/A interface in these NF devices are all reduced to less than 0.18 eV. In particular, in some cases, the additional emission from pure material is favorable for suppressing the non-radiative CT states decay. Consequently, the recombination losses in these NF systems are reduced to 0.5 eV, while the charge generation is still efficient as confirmed by PL quenching and EQEPV.

    Novel material systems based on non-fullerene acceptors are investigated. The systems performed energy offsets (ΔHOMO or ΔLUMO) less than 0.15eV, resulting in the same energy of CT states and bulk excitons. In this regard, the charge transfer energy loss is minimized. We also found that the EL spectra as well as the EQEEL of the blend solar cells are similar with that of lower gap components in blends. Thus the non-radiative voltage losses are reduced to < 0.3V and small voltage loss of 0.5-0.7V are obtained. Meanwhile, the charge generation in systems are still efficient and high EQEPV of 50-70% can be achieved. It confirms that there is no intrinsic limit for the VOC and efficiency of OPVs as compared with other photovoltaic technologies.

    List of papers
    1. Modulating molecular aggregation by facile heteroatom substitution of diketopyrrolopyrrole based small molecules for efficient organic solar cells
    Open this publication in new window or tab >>Modulating molecular aggregation by facile heteroatom substitution of diketopyrrolopyrrole based small molecules for efficient organic solar cells
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    2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 48, 24349-24357 p.Article in journal (Refereed) Published
    Abstract [en]

    In conjugated polymers and small molecules of organic solar cells, aggregation induced by intermolecular interactions governs the performance of photovoltaics. However, little attention has been paid to the connection between molecular structure and aggregation within solar cells based on soluble small molecules. Here we demonstrate modulation of intermolecular aggregation of two synthesized molecules through heteroatom substitution to develop an understanding of the role of aggregation in conjugated molecules. Molecule 1 (M1) based on 2-ethylhexyloxy-benzene substituted benzo[1,2-b:4,5-b]dithiophene (BDTP) and diketopyrrolopyrrole (DPP) displays strong aggregation in commonly used organic solvents, which is reduced in molecule 2 (M2) by facile oxygen atom substitution on the BDTP unit confirmed by absorption spectroscopy and optical microscopy, while it successfully maintains molecular planarity and favorable charge transport characteristics. Solar cells based on M2 exhibit more than double the photocurrent of devices based on M1 and yield a power conversion efficiency of 5.5%. A systematic investigation of molecular conformation, optoelectronic properties, molecular packing and crystallinity as well as film morphology reveals structure dependent aggregation responsible for the performance difference between the two conjugated molecules.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2015
    National Category
    Biological Sciences Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-123846 (URN)10.1039/c5ta06501a (DOI)000366163000022 ()
    Note

    Funding Agencies|Swedish Energy Agency; China Scholarship Council (CSC)

    Available from: 2016-01-11 Created: 2016-01-11 Last updated: 2017-08-18
    2. A fused-ring based electron acceptor for efficient non-fullerene polymer solar cells with small HOMO offset
    Open this publication in new window or tab >>A fused-ring based electron acceptor for efficient non-fullerene polymer solar cells with small HOMO offset
    Show others...
    2016 (English)In: NANO ENERGY, ISSN 2211-2855, Vol. 27, 430-438 p.Article in journal (Refereed) Published
    Abstract [en]

    A non-fullerene electron acceptor bearing a novel backbone with fused 10-heterocyclic ring (in-dacenodithiopheno-indacenodiselenophene), denoted by IDTIDSe-IC is developed for fullerene free polymer solar cells. IDTIDSe-IC exhibits a low band gap (E-g=1.52 eV) and strong absorption in the 600850 nm region. Combining with a large band gap polymer J51 (E-g=1.91 eV) as donor, broad absorption coverage from 300 nm to 800 nm is obtained due to complementary absorption of J51 and IDTIDSe-IC, which enables a high PCE of 8.02% with a V-oc of 0.91 V, a J(SC) of 15.16 mA/cm(2) and a FF of 58.0% in the corresponding PSCs. Moreover, the EQE of 50-65% is achieved in the absorption range of IDTIDSe-IC with only about 0.1 eV HOMO difference between J51 and IDTIDSe-IC. (C) 2016 Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE BV, 2016
    Keyword
    Non-fullerene acceptor; Indacenodithiophene; Polymer solar cells
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-132487 (URN)10.1016/j.nanoen.2016.07.019 (DOI)000384910500047 ()
    Note

    Funding Agencies|National Natural Science Foundation of China [21504062, 21572152]; China Postdoctoral Science Foundation [2015M581853]; Jiangsu Province Postdoctoral Science Foundation [1501024B]; Vinnova [2015-04751]; China Scholarship Council (CSC) [201306730002]; Swedish Research Council (VR) [621-2013-5561]; Swedish Energy Agency [EM 42033-1]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]; Collaborative Innovation Center of Suzhou Nano Science and Technology; Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)

    Available from: 2016-11-13 Created: 2016-11-12 Last updated: 2017-08-18
    3. Fast charge separation in a non-fullerene organic solar cell with a small driving force
    Open this publication in new window or tab >>Fast charge separation in a non-fullerene organic solar cell with a small driving force
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    2016 (English)In: NATURE ENERGY, ISSN 2058-7546, Vol. 1, 16089Article in journal (Refereed) Published
    Abstract [en]

    Fast and efficient charge separation is essential to achieve high power conversion efficiency in organic solar cells (OSCs). In state-of-the-art OSCs, this is usually achieved by a significant driving force, defined as the offset between the bandgap (E-gap) of the donor/acceptor materials and the energy of the charge transfer (CT) state (E-CT), which is typically greater than 0.3 eV. The large driving force causes a relatively large voltage loss that hinders performance. Here, we report non-fullerene OSCs that exhibit ultrafast and efficient charge separation despite a negligible driving force, as E-CT is nearly identical to E-gap. Moreover, the small driving force is found to have minimal detrimental effects on charge transfer dynamics of the OSCs. We demonstrate a non-fullerene OSC with 9.5% efficiency and nearly 90% internal quantum efficiency despite a low voltage loss of 0.61V. This creates a path towards highly efficient OSCs with a low voltage loss.

    Place, publisher, year, edition, pages
    NATURE PUBLISHING GROUP, 2016
    National Category
    Other Physics Topics
    Identifiers
    urn:nbn:se:liu:diva-135409 (URN)10.1038/NENERGY.2016.89 (DOI)000394175200001 ()
    Note

    Funding Agencies|National Basic Research Program of China (973 Program) [2013CB834701, 2014CB643501]; Hong Kong Research Grants Council [T23-407/13 N, N_HKUST623/13, 606012]; HK JEBN Limited; National Science Foundation of China [21374090, 51361165301]; Office of Naval Research [N000141410531, N000141512322, N000141310526 P00002]; Office of Science, Office of Basic Energy Sciences, of the US Department of Energy [DE-AC02-05CH11231]; Swedish Research Council (VR) [330-2014-6433]; Swedish Research Council (FORMAS) [942-2015-1253]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (faculty grant SFO-Mat-LiU) [2009-00971]; European Commission [691210, INCA 600398]; Wallenberg Scholar grant

    Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2017-08-18
  • Public defence: 2017-09-15 13:15 K1, Kåkenhus, Norrköping
    Martín-Bylund, Anna
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Educational Sciences.
    Towards a minor bilingualism: Exploring variations of language and literacy in early childhood education2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this compilation thesis is to explore variations in bilingualism with the help of everyday specific situations at a Spanish-Swedish early childhood institution in Sweden, and by means of a ‘material-semiotic theorizing’. This means that material and semiotic elements are treated equally and entwined. Through studying a bilingual preschool practice, theory and politics as three interwoven practices, the thesis produces knowledge on language and literacy as socially and materially divergent, transformative occurrences. The research process is a commitment with Deleuzio-Guattarian philosophy, theory and politics, and is defined as a becoming in and of the three practices (education, theory, politics). Ethical and methodological undertakings are described as results of the interaction of these practices. Processes of data production include a yearlong fieldwork with all year groups (1-5) at a bilingual preschool in Sweden with a Spanish-Swedish language policy. The materials of data (approx. 59 hours of video-recordings and additional field-notes of everyday activities) are extended and developed upon in interaction with theoretical concepts and political concerns in terms of an analytical process that ‘puts theory to work’. The results are phrased as three temporal suggestions: 1) Bilingualism is a plural, collectively produced, both transitory and specific phenomenon 2) Bilingualism emerges with different, simultaneous dimensions of language and literacy (language as both code and material intensities) 3) Bilingualism is shared and public but also private and inconclusive. The thesis also shows the interconnectedness and continuity between different constructions of bilingualism (i.e. separate – flexible, public - private) as well as the productivity of the unknown and of what is labelled as (il)literate expertise. The impact that these suggestions may have in working with bilingualism in early childhood education is discussed. At the same time the discussion inspires to thinking towards a minor bilingualism also in more general terms.

    List of papers
    1. Playing the game and speaking the right language: Language policy and materiality in a bilingual preschool activity.
    Open this publication in new window or tab >>Playing the game and speaking the right language: Language policy and materiality in a bilingual preschool activity.
    2017 (English)In: Multilingua - Journal of Cross-cultural and Interlanguage Communiciation, ISSN 0167-8507, E-ISSN 1613-3684, Vol. 36, no 4, 23 p.477-499 p.Article in journal (Refereed) Published
    Abstract [en]

    What are the material-semiotic relationships between a language policy and a table game activity in a bilingual preschool? Using Actor-Network Theory (ANT), the aim of this article is to explore this question, working with both human and nonhuman aspects of the activity, symmetrically, at the same level. The game playing activity takes place at a bilingual, Spanish-Swedish preschool in Sweden, which adopts a 50-50 approach in daily interaction. In interplay with video recordings, field notes and Actor-Network Theory, four different actor-network scenes of the activity are produced. Children, teacher, game pieces, die, cards, linguistic and other elements are described in the same language, as well as symmetrically drawn together in material-semiotic relations. The results indicate that the activity revolves mainly around two different, multilayered, and sometimes conflicting interests: to play the game and to speak the right language. The article describes the interrelatedness between these interests and how bilingualism emerges, transforms and becomes temporarily different in the relations of the actor-network. The approach opens up new avenues for understanding different constructions of bilingualism not in terms of a flexible-separate dichotomy but as entangled with one another in materialsemiotic relations, which may illuminate creative potentials in the relations of policy and practice rather than implementation. [ABSTRACT FROM AUTHOR]

    Place, publisher, year, edition, pages
    Berlin: Mouton de Gruyter, 2017. 23 p.
    Keyword
    Actor-Network Theory %28ANT%29, bilingualism, early childhood education, flexible-separate, human and nonhuman, language policy, material-semiotic
    National Category
    Specific Languages
    Identifiers
    urn:nbn:se:liu:diva-139851 (URN)10.1515/multi-2016-0021 (DOI)
    Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2017-08-17Bibliographically approved
    2. Multilingual becoming in reading: a picture storybook-reading-assemblage in early years education
    Open this publication in new window or tab >>Multilingual becoming in reading: a picture storybook-reading-assemblage in early years education
    2015 (English)In: Early Years Second Language Education: International perspectives on theory and practice / [ed] Sandie Mourão and Mónica Lourenco, Abingdon och New York: Routledge, 2015, 1, 78-92 p.Chapter in book (Other academic)
    Place, publisher, year, edition, pages
    Abingdon och New York: Routledge, 2015 Edition: 1
    Series
    Routledge research in early childhood education
    Keyword
    multilingualism, preschool, literacy, Multiple Literacies Theory
    National Category
    Sociology
    Identifiers
    urn:nbn:se:liu:diva-117976 (URN)978-0-415-70527-1 (ISBN)978-1-315-88994-8 (ISBN)
    Projects
    Språkpolicy i flerspråkiga förskolor och familjer: institutionella och vardagliga praktiker
    Funder
    Swedish Research Council, 721-2011-5842
    Available from: 2015-05-19 Created: 2015-05-19 Last updated: 2017-08-17
    3. The matter of silence in early childhood bilingual education
    Open this publication in new window or tab >>The matter of silence in early childhood bilingual education
    2017 (English)In: Educational Philosophy and Theory, ISSN 0013-1857, E-ISSN 1469-5812, Vol. 1, 1-10 p.Article in journal (Refereed) Published
    Abstract [en]

    The relationship between silence as non-speech and bilingualism in early childhood education is intricate. This article maps this relationship with the help of diverse theoretical entrances to a video-recorded everyday episode from a bilingual (Spanish–Swedish) preschool in Sweden. Though this, three alternative readings of silence are produced. Thinking with Deleuzian philosophy, the aim is to consider how the different readings of silence require different understandings of both time and language and allow different bilingual child subjectivities. The different readings present silence as development, strategy and intensity. Thinking with different dimensions of language as well as Chronosand Aion as different notions of time, the article shows that silence as development and silence as strategy are individually, chronologically and linguistically oriented readings. These allow viewing the bilingual child as more or less competent, active and powerful in relation to adults. Furthermore, silence as intensity is collectively produced as well as temporally unbounded, and produces the bilingual child, as involved in several material–semiotic relations capable of amazement. It is discussed whether, due to the evasive and inconsistent nature of silence, all three readings are equally (im)possible. Nevertheless, they produce different effects and raise different questions concerning bilingual educational practice in the early years.

    Place, publisher, year, edition, pages
    Abington: Routledge, 2017
    Keyword
    Silence and bilingualism, Deleuze, Chronos and Aion, different dimensions of language
    National Category
    General Language Studies and Linguistics Specific Languages Pedagogy Pedagogical Work Sociology (excluding Social Work, Social Psychology and Social Anthropology)
    Identifiers
    urn:nbn:se:liu:diva-139852 (URN)10.1080/00131857.2017.1361820 (DOI)
    Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2017-08-17Bibliographically approved
  • Public defence: 2017-09-15 13:15 VAL, Vallfarten, Linköping
    Andersson, Réka
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Gränsdragningar i Vårdens Vardag: Hanteringen av arbetsrelaterad psykisk ohälsa i det svenska välfärdssystemet2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Mental ill health in working life is a major and growing problem in the welfare society. The problem is multifaceted and raises many questions about who is responsible, what kind of phenomenon it is and how it should be managed. This study examines how care professionals manage work-related mental ill health. Focusing on occupational healthcare and primary care, interest is directed towards how care professionals argue about workrelated mental illness, what dilemmas they face and the strategies they rely on in managing them. It also seeks to answer the question of responsibility regarding this complex problem, not least in the light of the privatization of occupational healthcare.

    The study uses a multidisciplinary perspective, combining concepts from technology and science studies (STS), sociology of professions and organizational theory in order to analyze various aspects of care management of work-related mental ill health. The empirical material is mainly based on interviews with physicians, psychotherapists, counsellors, occupational therapists, psychologists, rehabilitation coordinators and behavioral scientists, but also includes observations in primary care and occupational health care. The management of work-related mental ill health in everyday healthcare practice is characterized by the fact that the cause of the problem is complex, the division of responsibility unclear and that psychosocial causes of disease are controversial. The study discusses the challenges and possibilities of managing this complex problem in a broad sense. The analysis pays attention to the drawing of boundaries by the care professionals regarding both responsibility and the phenomenon of work-related mental illness. The concept of knowledge infrastructure is used to explain and understand the knowledge and material structures that the care professionals work within. The analysis shows that the care professionals have a pragmatic approach and use different strategies to create scope for dealing with work-related mental health.

  • Public defence: 2017-09-22 10:00 Sal ACAS, Hus A, Linköping
    Gustafsson, Mariana S.
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Reassembling Local E-Government: A study of actors’ translations of digitalisation in public administration2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The digitalisation of society decidedly affects public administration. Swedish public administration has long worked with information technologies for an effective and improved management of public services. But new and increased use of information technologies in society poses new challenges. New demands on information security are increasing, while accessibility and transparency are important priorities in policies on digitalisation in public services. However, the central government’s ambitions and expectations with regard to digitalisation face a slow and hesitant implementation in local governments. There are important differences between municipalities in priorities, local needs, and implementation mechanisms in connection with e-government. In this thesis, I argue there is a need to reconsider the role of governance mechanisms in e-government. There is a need to understand local translations of national policies and technological developments in relation to the goals of more effective and legitimate public administration. The main purpose of this thesis is to analyse tensions that emerge in the implementation of egovernment in local public administration. On the basis of a constructivist and interpretivist approach, I have undertaken two empirical studies. One focuses on municipal administration of education in Linköping. The other focuses on a governance network on digitalisation policy in Östergötland. The studies are presented in four papers. The issues addressed in the papers are further analysed with a focus on four fields of tension, using network governance theory and translation theory. This shows that the implementation of e-government in local public administration is a tension-laden process. The four fields of tension relate to: different logics and dilemmas for adoption and implementation; concerns and ambiguities in a context of unclear organisational and institutional arrangements; concerns and resistance from professional users; and a reassessment of the meaning of security as a reference for the interpretation of information security. I contend that established managerial and evolutionary models of e-government leave important process-related aspects out of the analysis of change in public administration. The contribution of this thesis lies in its description and analysis of the four identified fields of tension. One significant implication of my analysis is that reassembling current  governance mechanisms in local public administration is crucial.

    List of papers
    1. Safe on-line e-services building legitimacy for e- government: A case study of public e-services in education in Sweden
    Open this publication in new window or tab >>Safe on-line e-services building legitimacy for e- government: A case study of public e-services in education in Sweden
    2013 (English)In: eJournal of eDemocracy & Open Government, ISSN 2075-9517, Vol. 5, no 2, 155-173 p.Article in journal (Refereed) Published
    Abstract [en]

    There is an increased use of public e-services integrating citizens into public administration through electronic interfaces. On-line interaction among public organizations and citizens is one core relation in e-government that hereby becomes embedded into daily practices. A safe entry into e-governmental systems is essential for security and trust in the e-governmental systems and schools as well as public services in general. This paper addresses how electronic identification has been used for access to public e-services in schools in a Swedish municipality. This paper draws on a case study of use of ICT platforms in education administration in order to study the implementation of secure login process and factors that may have implications upon trust in-and legitimacy of public e-services at local e-government level. Besides describing the implementation process and analyzing security and organizational arrangements connected to the use of the platform, the paper address the argument that secure identification tools are essential for increased use of e-services and lead to greater legitimacy of the public (e)services. The analysis focuses on information security, organization set-up and potential development of the platforms, contributing with empirical findings and conceptual applications. A key finding was that the organization of identification and access to public e-services seemed highly dependent of the organizational structure of the public schools. The more general implication of the findings was that safe and well organized identification systems that were considered as trustworthy and useful among citizens were essential for increased use of the services and legitimate public e-services in general. 

    Place, publisher, year, edition, pages
    Krems, Austria: Donau-Universitaet Krems, 2013
    Keyword
    local e-government, public e-services, education administration, legitimacy, electronic identification, information security
    National Category
    Public Administration Studies
    Identifiers
    urn:nbn:se:liu:diva-99916 (URN)
    Projects
    Future secure electronic identification - emergence and use of e-identification (FUSe)
    Available from: 2013-10-23 Created: 2013-10-23 Last updated: 2017-06-26Bibliographically approved
    2. Constructing security: reflections on the margins of a case study of the use of electronic identification in ICT platforms in schools
    Open this publication in new window or tab >>Constructing security: reflections on the margins of a case study of the use of electronic identification in ICT platforms in schools
    2014 (English)In: Privacy and Identity Management for Emerging Services and Technologies: 8th IFIP WG 9.2, 9.5, 9.6/11.7, 11.4, 11.6 International Summer School, Nijmegen, The Netherlands, June 17-21, 2013, Revised Selected Papers / [ed] M. Hansen, J.-H. Hoepman, R. Leenes, D. Whitehouse, Springer, 2014, 224-236 p.Chapter in book (Refereed)
    Abstract [en]

    This paper addresses how people construct meanings regarding “the concept of security”, based upon the descriptions collected from participants in a case study of the use of electronic identification in ICT platforms in schools. The aim of the paper is to reflect on the concept of security by identifying and analyzing how people build their own understanding of security when using ICT platforms in schools. The analysis identifies three ontological instances of security: security as an ideal state of affairs, security as a value and information security. The analysis also clarifies the difference between the objective and subjective nature of security, as well as the differences between factual and perceived information security. As a result, I raise several research questions concerning “security”, and identify common assumptions with regard to constructing the concept of security. 

    Place, publisher, year, edition, pages
    Springer, 2014
    Series
    IFIP Advances in Information and Communication Technology, ISSN 1868-4238 ; 421
    Keyword
    Security, ontological, epistemological, construction, meaning, empirical
    National Category
    Public Administration Studies Information Systems
    Identifiers
    urn:nbn:se:liu:diva-99931 (URN)10.1007/978-3-642-55137-6_18 (DOI)000342688200018 ()978-3-642-55136-9 (ISBN)
    Conference
    8th International IFIP Summer School on Privacy and Identity Management for Emerging Services and Technologies, 17-21 June 2013, Nijmegen, the Netherlands
    Available from: 2013-10-23 Created: 2013-10-23 Last updated: 2017-06-26Bibliographically approved
    3. Constructing identities: Professional use of eID in public organisations
    Open this publication in new window or tab >>Constructing identities: Professional use of eID in public organisations
    2015 (English)In: Transforming Government: People, Process and Policy, ISSN 1750-6166, E-ISSN 1750-6174, Vol. 9, no 2, 143-158 p.Article in journal (Refereed) Published
    Abstract [en]

    Purpose– The purpose of the paper is to reveal how identities are constructed when electronic identification (eIDs) cards are introduced through information systems in public organisations. Design/methodology/approach– Through two case studies, the authors generate rich data on the construction of identities through use of eID within public organisations. The author’s analysis, based on actor network theory, focusses on the translation of eIDs in these two settings. Findings– ID can be viewed as an artefact where the public and private spheres meet. The authors found at least three mixed roles in employees’ use of eID: as a purely private person; as a private person in the work place; and as a professional in the work place. Research limitations/implications– There is a need for further research on how eID is translated into organisational contexts and how institutional settings define the openings for local translation processes. However, the results are based on two small cases, meaning that broad generalisations are difficult to make. Practical implications– EID is so much more than technology. The technical framing of the identification system appears to be subordinated to organisational arrangements and cultures, making it important to apply a socio-technical perspective when working with eID. Originality/value– The empirical cases have offered a unique chance to study implementation and use of eID in two very different public service organisations. The findings illustrate how eID translated into organisational contexts, and how identity management within an organisational setting is linked to the employees’ private and professional roles.

    National Category
    Information Systems, Social aspects
    Identifiers
    urn:nbn:se:liu:diva-120124 (URN)10.1108/TG-11-2013-0049 (DOI)
    Available from: 2015-07-12 Created: 2015-07-12 Last updated: 2017-06-26
  • Public defence: 2017-09-22 13:15 Val, Vallfarten, Linköping
    Reindl, Katharina
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Implementing energy measures in renovations for multi-family dwellings: Influence and practice of professionals2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Aging buildings will sooner or later be in need of renovation, which opens opportunities to reduce energy use. Even if economically feasible energy measures or technologies exist, they are not always implemented, leading to an energy efficiency gap. This dissertation deals with how energy measures are handled and why they are enabled or disabled during the planning and design of renovations. During renovations, different kinds of building professionals are engaged, here referred to as middle professionals. The meeting practice of the professionals is investigated, with a focus on how the middle professionals exert influence from the middle-out and to the top and bottom, and how and why they enable or disable measures aimed at energy efficiency or reduction. Three renovation projects are followed in the municipality-owned housing company Stångåstaden, in Linköping, Sweden. The housing company’s goal is to reduce the amount of purchased energy by 25% by 2025. Methods applied during the research are semi-structured interviews, participant observations and document analysis. The conclusions show that energy measures were implemented, but more can be done in renovations. Predefined meeting agendas make the process efficient but not flexible, thus it can be difficult to introduce innovations and alternative ways of thinking into the process. The professionals usually selected measures they had used before. Energy calculations attracted little interest compared to the aggregated knowledge from previous projects, and experience and tacit knowledge were highly valued. This and more lead to a renovation process where it is difficult for energy to enter the current meeting practice.

  • Public defence: 2017-09-26 13:15 Ada Lovelace, Linköping
    Dragisic, Zlatan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Completion of Ontologies and Ontology Networks2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The World Wide Web contains large amounts of data, and in most cases this data has no explicit structure. The lack of structure makes it difficult for automated agents to understand and use such data. A step towards a more structured World Wide Web is the Semantic Web, which aims at introducing semantics to data on the World Wide Web. One of the key technologies in this endeavour are ontologies, which provide a means for modeling a domain of interest and are used for search and integration of data.

    In recent years many ontologies have been developed. To be able to use multiple ontologies it is necessary to align them, i.e., find inter-ontology relationships. However, developing and aligning ontologies is not an easy task and it is often the case that ontologies and their alignments are incorrect and incomplete. This can be a problem for semantically-enabled applications. Incorrect and incomplete ontologies and alignments directly influence the quality of the results of such applications, as wrong results can be returned and correct results can be missed. This thesis focuses on the problem of completing ontologies and ontology networks.

    The contributions of the thesis are threefold. First, we address the issue of completing the is-a structure and alignment in ontologies and ontology networks. We have formalized the problem of completing the is-a structure in ontologies as an abductive reasoning problem and developed algorithms as well as systems for dealing with the problem. With respect to the completion of alignments, we have studied system performance in the Ontology Alignment Evaluation Initiative, a yearly evaluation campaign for ontology alignment systems. We have also addressed the scalability of ontology matching, which is one of the current challenges, by developing an approach for reducing the search space when generating the alignment.Second, high quality completion requires user involvement. As users' time and effort are a limited resource we address the issue of limiting and facilitating user interaction in the completion process. We have conducted a broad study of state-of-the-art ontology alignment systems and identified different issues related to the process. We have also conducted experiments to assess the impact of user errors in the completion process.

    While the completion of ontologies and ontology networks can be done at any point in the life-cycle of ontologies and ontology networks, some of the issues can be addressed already in the development phase. The third contribution of the thesis addresses this by introducing ontology completion and ontology alignment into an existing ontology development methodology.

    List of papers
    1. Completing the is-a structure in light-weight ontologies
    Open this publication in new window or tab >>Completing the is-a structure in light-weight ontologies
    2015 (English)In: Journal of Biomedical Semantics, ISSN 2041-1480, Vol. 6, 12Article in journal (Refereed) Published
    Abstract [en]

     Background: With the increasing presence of biomedical data sources on the Internet more and more research effort is put into finding possible ways for integrating and searching such often heterogeneous sources. Ontologies are a key technology in this effort. However, developing ontologies is not an easy task and often the resulting ontologies are not complete. In addition to being problematic for the correct modelling of a domain, such incomplete ontologies, when used in semantically-enabled applications, can lead to valid conclusions being missed.

    Results: We consider the problem of repairing missing is-a relations in ontologies. We formalize the problem as a generalized TBox abduction problem. Based on this abduction framework, we present complexity results for the existence, relevance and necessity decision problems for the generalized TBox abduction problem with and without some specific preference relations for ontologies that can be represented using a member of the EL family of description logics. Further, we present algorithms for finding solutions, a system as well as experiments.

    Conclusions: Semantically-enabled applications need high quality ontologies and one key aspect is their completeness. We have introduced a framework and system that provides an environment for supporting domain experts to complete the is-a structure of ontologies. We have shown the usefulness of the approach in different experiments. For the two Anatomy ontologies from the Ontology Alignment Evaluation Initiative, we repaired 94 and 58 initial given missing is-a relations, respectively, and detected and repaired additionally, 47 and 10 missing is-a relations. In an experiment with BioTop without given missing is-a relations, we detected and repaired 40 new missing is-a relations.

    National Category
    Computer Science Bioinformatics (Computational Biology)
    Identifiers
    urn:nbn:se:liu:diva-116628 (URN)10.1186/s13326-015-0002-8 (DOI)000353197200001 ()25883780 (PubMedID)
    Funder
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)
    Available from: 2015-03-29 Created: 2015-03-29 Last updated: 2017-08-21
    2. Get my pizza right: Repairing missing is-a relations in ALC ontologies
    Open this publication in new window or tab >>Get my pizza right: Repairing missing is-a relations in ALC ontologies
    2012 (English)In: Second Joint International Semantic Technology Conference, Springer Berlin/Heidelberg, 2012, 17-32 p.Chapter in book (Refereed)
    Abstract [en]

    With the increased use of ontologies in semantically-enabled applications, the issue of debugging defects in ontologies has become increasingly important. These defects can lead to wrong or incomplete results for the applications. Debugging consists of the phases of detection and repairing. In this paper we focus on the repairing phase of a particular kind of defects, i.e. the missing relations in the is-a hierarchy. Previous work has dealt with the case of taxonomies. In this work we extend the scope to deal with ALC ontologies that can be represented using acyclic terminologies. We present algorithms and discuss a system.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2012
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 (print), 1611-3349 (online) ; 7774
    Keyword
    ontologies, ontology engineering, ontology debugging, knowledge representation
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-91435 (URN)10.1007/978-3-642-37996-3_2 (DOI)978-3-642-37995-6 (ISBN)978-3-642-37996-3 (ISBN)
    Funder
    Swedish e‐Science Research CenterSwedish Research Council, 2010-4759CUGS (National Graduate School in Computer Science)
    Available from: 2013-04-24 Created: 2013-04-24 Last updated: 2017-08-21
    3. Reducing the search space in ontology alignment using clustering techniques and topic identification
    Open this publication in new window or tab >>Reducing the search space in ontology alignment using clustering techniques and topic identification
    2015 (English)In: Proceedings of the 8th International Conference on Knowledge Capture, New York: ACM Digital Library, 2015, 21- p.Conference paper, (Refereed)
    Abstract [en]

    One of the current challenges in ontology alignment is scalability and one technique to deal with this issue is to reduce the search space for the generation of mapping suggestions. In this paper we develop a method to prune that search space by using clustering techniques and topic identification. Further, we provide experiments showing that we are able to generate partitions that allow for high quality alignments with a highly reduced effort for computation and validation of mapping suggestions for the parts of the ontologies in the partition. Other techniques will still be needed for finding mappings that are not in the partition.

    Place, publisher, year, edition, pages
    New York: ACM Digital Library, 2015
    Keyword
    Knowledge representation, data mining, ontology alignment
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-121838 (URN)10.1145/2815833.2816959 (DOI)978-1-4503-3849-3 (ISBN)
    Conference
    8th International Conference on Knowledge Capture
    Funder
    CUGS (National Graduate School in Computer Science)Swedish e‐Science Research CenterEU, FP7, Seventh Framework Programme, FP7-IP-608142
    Available from: 2015-10-09 Created: 2015-10-09 Last updated: 2017-08-21
    4. Experiences from the Anatomy track in the Ontology Alignment Evaluation Initiative
    Open this publication in new window or tab >>Experiences from the Anatomy track in the Ontology Alignment Evaluation Initiative
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Background: One of the longest running tracks in the Ontology Alignment Evaluation Initiative is the Anatomy track which focuses on aligning two anatomy ontologies. The Anatomy track was started in 2005. In 2005 and 2006 the task in this track was to align the Foundational Model of Anatomy and the OpenGalen Anatomy Model. Since 2007 the ontologies used in the track are the Adult Mouse Anatomy and a part of the NCI Thesaurus. Since 2015 the data in the Anatomy track is also used in the Interactive track of the Ontology Alignment Evaluation Initiative.

    Results: In this paper we focus on the Anatomy track in the years 2007-2016 and the Anatomy part of the Interactive track in 2015-2016. We describe the data set and the changes it went through during the years. Further, we give an overview of all systems that participated in the track and the techniques they have used. We discuss the performance results of the systems and summarize the general trends.

    Conclusions: About 50 systems have participated in the Anatomy track. Many different techniques were used. The most popular matching techniques are string-based strategies and structure-based techniques. Many systems also use auxiliary information. The quality of the alignment has increased for the best performing systems since the beginning of the track and more and more systems check the coherence of the proposed alignment and implement a repair strategy.Further, interacting with an oracle is beneficial.

    Keyword
    ontologies, ontology matching, OAEI, anatomy
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-139775 (URN)
    Funder
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)EU, FP7, Seventh Framework Programme, FP7-IP-608142
    Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2017-08-21
    5. User validation in ontology alignment
    Open this publication in new window or tab >>User validation in ontology alignment
    Show others...
    2016 (English)In: The Semantic Web – ISWC 2016: 15th International Semantic Web Conference, Kobe, Japan, October 17–21, 2016, Proceedings, Part I / [ed] Paul Groth, Elena Simperl, Alasdair Gray, Marta Sabou, Markus Krötzsch, Freddy Lecue, Fabian Flöck and Yolanda Gil, Cham, Switzerland: Springer Publishing Company, 2016, 200-217 p.Chapter in book (Refereed)
    Abstract [en]

    User validation is one of the challenges facing the ontology alignment community, as there are limits to the quality of automated alignment algorithms. In this paper we present a broad study on user validation of ontology alignments that encompasses three distinct but interrelated aspects: the profile of the user, the services of the alignment system, and its user interface. We discuss key issues pertaining to the alignment validation process under each of these aspects, and provide an overview of how current systems address them. Finally, we use experiments from the Interactive Matching track of the Ontology Alignment Evaluation Initiative (OAEI) 2015 to assess the impact of errors in alignment validation, and how systems cope with them as function of their services.

    Place, publisher, year, edition, pages
    Cham, Switzerland: Springer Publishing Company, 2016
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 (print), 1611-3349 (online) ; 9981
    Keyword
    knowledge representation, user interfaces, ontology engineering, ontology alignment
    National Category
    Computer Science
    Identifiers
    urn:nbn:se:liu:diva-131806 (URN)10.1007/978-3-319-46523-4_13 (DOI)000389086500013 ()9783319465227 (ISBN)9783319465234 (ISBN)
    Funder
    Swedish e‐Science Research CenterCUGS (National Graduate School in Computer Science)EU, FP7, Seventh Framework Programme, FP7-IP-608142
    Available from: 2016-10-07 Created: 2016-10-07 Last updated: 2017-08-21Bibliographically approved
    6. Integrating Ontology Debugging and Matching into the eXtreme Design Methodology
    Open this publication in new window or tab >>Integrating Ontology Debugging and Matching into the eXtreme Design Methodology
    2015 (English)In: Proceedings of the 6th Workshop on Ontology and Semantic Web Patterns (WOP 2015) / [ed] Eva Blomqvist; Pascal Hitzler; Adila Krisnadhi; Tom Narock; Monika Solanki, Rheinisch-Westfaelische Technische Hochschule Aachen University , 2015Conference paper, (Refereed)
    Abstract [en]

    Ontology design patterns (ODPs) and related ontology development methodologies were designed as ways of sharing and reusing best practices in ontology engineering. However, while the use of these reduces the number of issues in the resulting ontologies defects can still be introduced into the ontology due to improper use or misinterpretation of the patterns. Thus, the quality of the developed ontologies is still a major concern. In this paper we address this issue by describing how ontology debugging and matching can be integrated in a state-of-the-art ontology development methodology based on ontology design patterns- the eXtreme Design methodology, and show the advantages in a case study based on a real world ontology.

    Place, publisher, year, edition, pages
    Rheinisch-Westfaelische Technische Hochschule Aachen University, 2015
    Series
    CEUR Workshop Proceedings, ISSN 1613-0073 ; 1461
    National Category
    Media and Communication Technology
    Identifiers
    urn:nbn:se:liu:diva-121794 (URN)
    Conference
    6th Workshop on Ontology and Semantic Web Patterns (WOP 2015), Bethlehem, Pensylvania, USA, October 11, 2015
    Funder
    EU, FP7, Seventh Framework Programme, FP7-IP-608142CUGS (National Graduate School in Computer Science)Swedish e‐Science Research Center
    Available from: 2015-10-06 Created: 2015-10-06 Last updated: 2017-08-21Bibliographically approved