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  • Public defence: 2020-02-28 09:15 Domteatern, Norrköping
    Hajisharif, Saghi
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Computational Photography: High Dynamic Rangeand Light Fields2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The introduction and recent advancements of computational photography have revolutionized the imaging industry. Computational photography is a combination of imaging techniques at the intersection of various fields such as optics, computer vision, and computer graphics. These methods enhance the capabilities of traditional digital photography by applying computational techniques both during and after the capturing process. This thesis targets two major subjects in this field: High Dynamic Range (HDR) image reconstruction and Light Field (LF) compressive capturing, compression, and real-time rendering.

    The first part of the thesis focuses on the HDR images that concurrently contain detailed information from the very dark shadows to the brightest areas in the scenes. One of the main contributions presented in this thesis is the development of a unified reconstruction algorithm for spatially variant exposures in a single image. This method is based on a camera noise model, and it simultaneously resamples, reconstructs, denoises, and demosaics the image while extending its dynamic range. Furthermore, the HDR reconstruction algorithm is extended to adapt to the local features of the image, as well as the noise statistics, to preserve the high-frequency edges during reconstruction.

    In the second part of this thesis, the research focus shifts to the acquisition, encoding, reconstruction, and rendering of light field images and videos in a real-time setting. Unlike traditional integral photography, a light field captures the information of the dynamic environment from all angles, all points in space, and all spectral wavelength and time. This thesis employs sparse representation to provide an end-to-end solution to the problem of encoding, real-time reconstruction, and rendering of high dimensional light field video data sets. These solutions are applied on various types of data sets, such as light fields captured with multi-camera systems or hand-held cameras equipped with micro-lens arrays, and spherical light fields. Finally, sparse representation of light fields was utilized for developing a single sensor light field video camera equipped with a color-coded mask. A new compressive sensing model is presented that is suitable for dynamic scenes with temporal coherency and is capable of reconstructing high-resolution light field videos.  

    List of papers
    1. HDR reconstruction for alternating gain (ISO) sensor readout
    Open this publication in new window or tab >>HDR reconstruction for alternating gain (ISO) sensor readout
    2014 (English)In: Eurographics 2014 short papers, 2014Conference paper, Published paper (Refereed)
    Abstract [en]

    Modern image sensors are becoming more and more flexible in the way an image is captured. In this paper, we focus on sensors that allow the per pixel gain to be varied over the sensor and develop a new technique for efficient and accurate reconstruction of high dynamic range (HDR) images based on such input data. Our method estimates the radiant power at each output pixel using a sampling operation which performs color interpolation, re-sampling, noise reduction and HDR-reconstruction in a single step. The reconstruction filter uses a sensor noise model to weight the input pixel samples according to their variances. Our algorithm works in only a small spatial neighbourhood around each pixel and lends itself to efficient implementation in hardware. To demonstrate the utility of our approach we show example HDR-images reconstructed from raw sensor data captured using off-the shelf consumer hardware which allows for two different gain settings for different rows in the same image. To analyse the accuracy of the algorithm, we also use synthetic images from a camera simulation software.

    Keywords
    HDR, image reconstruction, dual-ISO, image processing
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-104922 (URN)
    Conference
    Eurographics, Strasbourg, France, April 7-11, 2014
    Projects
    VPS
    Available from: 2014-03-03 Created: 2014-03-03 Last updated: 2020-02-18Bibliographically approved
    2. Adaptive dualISO HDR-reconstruction
    Open this publication in new window or tab >>Adaptive dualISO HDR-reconstruction
    2015 (English)In: EURASIP Journal on Image and Video Processing, ISSN 1687-5176, E-ISSN 1687-5281Article in journal (Refereed) Published
    Abstract [en]

    With the development of modern image sensors enabling flexible image acquisition, single shot HDR imaging is becoming increasingly popular. In this work we capture single shot HDR images using an imaging sensor with spatially varying gain/ISO. In comparison to previous single shot HDR capture based on a single sensor, this allows all incoming photons to be used in the imaging, instead of wasting incoming light using spatially varying ND-filters, commonly used in previous works. The main technical contribution in this work is an  extension of previous HDR reconstruction approaches for single shot HDR imaging based on local polynomial approximations [15,10]. Using a sensor noise model, these works deploy a statistically informed filtering operation to reconstruct HDR pixel values. However, instead of using a fixed filter size, we introduce two novel algorithms for adaptive filter kernel selection. Unlike previous works, using  adaptive filter kernels [16], our algorithms are based on analysing the model fit and the expected statistical deviation of the estimate based on the sensor noise model. Using an iterative procedure we can then adapt the filter kernel according to the image structure and the statistical image noise. Experimental results show that the proposed filter de-noises the noisy image carefully while well preserving the important image features such as edges and corners, outperforming previous methods. To demonstrate the robustness of our approach, we have exploited input images from raw sensor data using a commercial off-the shelf camera. To further analyze our algorithm, we have also implemented a camera simulator to evaluate different gain pattern and noise properties of the sensor.

    Place, publisher, year, edition, pages
    Springer Publishing Company, 2015
    Keywords
    HDR reconstruction; Single shot HDR imaging; DualISO; Statistical image fitlering
    National Category
    Computer Sciences Computer and Information Sciences
    Identifiers
    urn:nbn:se:liu:diva-122587 (URN)10.1186/s13640-015-0095-0 (DOI)000366324500001 ()
    Note

    Funding agencies: Swedish Foundation for Strategic Research (SSF) [IIS11-0081]; Linkoping University Center for Industrial Information Technology (CENIIT); Swedish Research Council through the Linnaeus Environment CADICS

    Available from: 2015-11-10 Created: 2015-11-10 Last updated: 2020-02-18Bibliographically approved
    3. A Unified Framework for Compression and Compressed Sensing of Light Fields and Light Field Videos
    Open this publication in new window or tab >>A Unified Framework for Compression and Compressed Sensing of Light Fields and Light Field Videos
    2019 (English)In: ACM Transactions on Graphics, ISSN 0730-0301, E-ISSN 1557-7368, Vol. 38, no 3, p. 1-18, article id 23Article in journal (Refereed) Published
    Abstract [en]

    In this article we present a novel dictionary learning framework designed for compression and sampling of light fields and light field videos. Unlike previous methods, where a single dictionary with one-dimensional atoms is learned, we propose to train a Multidimensional Dictionary Ensemble (MDE). It is shown that learning an ensemble in the native dimensionality of the data promotes sparsity, hence increasing the compression ratio and sampling efficiency. To make maximum use of correlations within the light field data sets, we also introduce a novel nonlocal pre-clustering approach that constructs an Aggregate MDE (AMDE). The pre-clustering not only improves the image quality but also reduces the training time by an order of magnitude in most cases. The decoding algorithm supports efficient local reconstruction of the compressed data, which enables efficient real-time playback of high-resolution light field videos. Moreover, we discuss the application of AMDE for compressed sensing. A theoretical analysis is presented that indicates the required conditions for exact recovery of point-sampled light fields that are sparse under AMDE. The analysis provides guidelines for designing efficient compressive light field cameras. We use various synthetic and natural light field and light field video data sets to demonstrate the utility of our approach in comparison with the state-of-the-art learning-based dictionaries, as well as established analytical dictionaries.

    Place, publisher, year, edition, pages
    ACM Digital Library, 2019
    Keywords
    Light field video compression, compressed sensing, dictionary learning, light field photography
    National Category
    Computer and Information Sciences
    Identifiers
    urn:nbn:se:liu:diva-158026 (URN)10.1145/3269980 (DOI)000495415600005 ()
    Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2020-02-18Bibliographically approved
    4. Light Field Video Compression and Real Time Rendering
    Open this publication in new window or tab >>Light Field Video Compression and Real Time Rendering
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    2019 (English)In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 38, p. 265-276Article in journal (Refereed) Published
    Abstract [en]

    Light field imaging is rapidly becoming an established method for generating flexible image based description of scene appearances. Compared to classical 2D imaging techniques, the angular information included in light fields enables effects such as post‐capture refocusing and the exploration of the scene from different vantage points. In this paper, we describe a novel GPU pipeline for compression and real‐time rendering of light field videos with full parallax. To achieve this, we employ a dictionary learning approach and train an ensemble of dictionaries capable of efficiently representing light field video data using highly sparse coefficient sets. A novel, key element in our representation is that we simultaneously compress both image data (pixel colors) and the auxiliary information (depth, disparity, or optical flow) required for view interpolation. During playback, the coefficients are streamed to the GPU where the light field and the auxiliary information are reconstructed using the dictionary ensemble and view interpolation is performed. In order to realize the pipeline we present several technical contributions including a denoising scheme enhancing the sparsity in the dataset which enables higher compression ratios, and a novel pruning strategy which reduces the size of the dictionary ensemble and leads to significant reductions in computational complexity during the encoding of a light field. Our approach is independent of the light field parameterization and can be used with data from any light field video capture system. To demonstrate the usefulness of our pipeline, we utilize various publicly available light field video datasets and discuss the medical application of documenting heart surgery.

    Place, publisher, year, edition, pages
    John Wiley & Sons, 2019
    Keywords
    Computational photography, Light Fields, Light Fields Compression, Light Field Video
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-162100 (URN)10.1111/cgf.13835 (DOI)000496351100025 ()
    Conference
    Pacific Graphics 2019
    Note

    Funding agencies:  childrens heart clinic at Skane University hospital, Barnhjartcentrum; strategic research environment ELLIIT; Swedish Science Council [201505180]; VinnovaVinnova [2017-03728]; Visual Sweden Platform for Augmented Intelligence

    Available from: 2019-11-19 Created: 2019-11-19 Last updated: 2020-02-18
  • Public defence: 2020-02-28 10:15 K3, Kåkenhus, Norrköping
    Shiran Chaharsoughi, Mina
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Hybrid Plasmonics for Energy Harvesting and Sensing of Radiation and Heat2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The special optical properties of subwavelength metallic structures have opened up for numerous applications in different fields. The interaction of light with metal nanostructures leads to the excitation of collective oscillations of conduction-band electrons, known as plasmons. These plasmon excitations are responsible for the high absorption and high scattering of light in metallic nanostructures. High absorption of light and the subsequent temperature increase in the nanostructures make them suitable as point-like heat sources that can be controlled remotely by light.

    The research presented in this thesis focuses on the development and studies of hybrid devices that combine light-induced heating in plasmonic nanostructures with other materials and systems. Particular focus is put on hybrid organic-inorganic systems for applications in energy harvesting as well as in heat and radiation sensing. Harvesting energy from light fluctuations was achieved in a hybrid device consisting of plasmonic gold nanodisk arrays and a pyroelectric copolymer. In this concept, fast and efficient light-induced heating in the gold nanodisks modulated the temperature of the pyroelectric layer, which could be used to extract electrical energy from fluctuations in simulated sunlight.

    Integrating plasmonic nanostructures with complementary materials can also provide novel hybrid sensors, for monitoring of temperature, heat flux and radiation. In this thesis work, a hybrid sensor was designed based on the combination of a plasmonic gold nanohole layer with a pyroelectric copolymer and an ionic thermoelectric gel. The gold nanohole arrays acted both as broadband light absorbers in the visible to near-infrared spectral range of the solar spectrum and also as one of the electrodes of the sensor. In contrast to the constituent components when used separately, the hybrid sensor could provide both fast and stable signals upon heat or radiation stimuli, as well as enhanced equilibrium signals.

    Furthermore, a concept for heat and radiation mapping was developed that was highly sensitive and stable despite its simple structure. The concept consisted of a gel-like electrolyte connecting two separated metal nanohole electrodes on a substrate. Resembling traditional thermocouples, this concept could autonomously detect temperature changes but with several orders of magnitudes higher sensitivity. Owing to its promising sensing properties as well as its compatibility with inexpensive mass production methods on flexible substrates, such concept may be particularly interesting for electronic skin applications for health monitoring and for humanoid robotics. Finally, we improved the possibilities for the temperature mapping of the concept by modifying the structure from lateral to vertical form. Similar to the lateral device, the vertical temperature sensor showed high temperature sensitivity and stability in producing signals upon temperature changes.

    List of papers
    1. Hybrid Plasmonic and Pyroelectric Harvesting of Light Fluctuations
    Open this publication in new window or tab >>Hybrid Plasmonic and Pyroelectric Harvesting of Light Fluctuations
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    2018 (English)In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071Article in journal (Refereed) Published
    Abstract [en]

    State-of-the-art solar energy harvesting systems based on photovoltaic technology require constant illumination for optimal operation. However, weather conditions and solar illumination tend to fluctuate. Here, a device is presented that extracts electrical energy from such light fluctuations. The concept combines light-induced heating of gold nanodisks (acting as plasmonic optical nanoantennas), and an organic pyroelectric copolymer film (poly(vinylidenefluoride-co-trifluoroethylene)), that converts temperature changes into electrical signals. This hybrid device can repeatedly generate current pulses, not only upon the onset of illumination, but also when illumination is blocked. Detailed characterization highlights the key role of the polarization state of the copolymer, while the copolymer thickness has minor influence on performance. The results are fully consistent with plasmon-assisted pyroelectric effects, as corroborated by combined optical and thermal simulations that match the experimental results. Owing to the tunability of plasmonic resonances, the presented concept is compatible with harvesting near infrared light while concurrently maintaining visible transparency.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2018
    Keywords
    Gold nanodisks, Plasmonic heating, Pyroelectric copolymers, Solar energy harvesting
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-148574 (URN)10.1002/adom.201701051 (DOI)000434349300001 ()
    Note

    Funding agencies: Wenner-Gren Foundations; Swedish Research Council [2015-05070]; Swedish Foundation for Strategic Research; AForsk Foundation; Royal Swedish Academy of Sciences; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Lin

    Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2020-01-31
    2. Thermodiffusion-Assisted Pyroelectrics-Enabling Rapid and Stable Heat and Radiation Sensing
    Open this publication in new window or tab >>Thermodiffusion-Assisted Pyroelectrics-Enabling Rapid and Stable Heat and Radiation Sensing
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    2019 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 28, article id 1900572Article in journal (Refereed) Published
    Abstract [en]

    Sensors for monitoring temperature, heat flux, and thermal radiation are essential for applications such as electronic skin. While pyroelectric and thermoelectric effects are suitable candidates as functional elements in such devices, both concepts show individual drawbacks in terms of zero equilibrium signals for pyroelectric materials and small or slow response of thermoelectric materials. Here, these drawbacks are overcome by introducing the concept of thermodiffusion-assisted pyroelectrics, which combines and enhances the performance of pyroelectric and ionic thermoelectric materials. The presented integrated concept provides both rapid initial response upon heating and stable synergistically enhanced signals upon prolonged exposure to heat stimuli. Likewise, incorporation of plasmonic metasurfaces enables the concept to provide both rapid and stable signals for radiation-induced heating. The performance of the concept and its working mechanism can be explained by ion-electron interactions at the interface between the pyroelectric and ionic thermoelectric materials.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2019
    Keywords
    heat sensing; ionic thermodiffusion; plasmonic heating; pyroelectric copolymer
    National Category
    Other Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-159730 (URN)10.1002/adfm.201900572 (DOI)000478851700007 ()2-s2.0-85064476505 (Scopus ID)
    Note

    Funding Agencies|Swedish Foundation for Strategic Research; Swedish Research Council; AForsk Foundation; Wenner-Gren Foundations; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [200900971]

    Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2020-01-31Bibliographically approved
  • Public defence: 2020-02-28 13:00 K2, Kåkenhus, Norrköping
    Wagrell, Kristin
    Linköping University, Department of Culture and Society, Division of Culture, Society, Design and Media. Linköping University, Faculty of Arts and Sciences.
    "Chorus of the Saved": Constructing the Holocaust Survivor in Swedish Public Discourse, 1943-19662020Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this dissertation I examine how the Holocaust survivor has been constructed in Swedish public discourse during the 1940s, 1950s and 1960s. This is done using a Foucauldian-inspired genealogical method through which an eclectic collection of sources—newsreels, films, radio programs, television programs and newspaper articles—is analyzed. The theoretical underpinnings of this analysis are based on Ian Hacking’s concept of discourse where the classification of survivor ‘types’ has a direct bearing on the expressions possible for those who are classified, i.e. individuals with Holocaust experience. The overarching research question of the dissertation therefore asks: how did a Holocaust survivor ‘type’ develop in Sweden during the 1940s, 50s and 60s?  The main thrust of the argument presented in the dissertation is that the concepts of ‘silence’ and ‘excess’ have always disciplined the ways in which Holocaust survivors have been conceived of as both victims and witnesses in Swedish public discourse. The communication of Jewish suffering by survivor-witnesses has both been framed as a dangerous, destructive force which could instigate unnecessary conflict while it, at the same time, has been positioned as a remedy to collective forgetfulness as well as a solution to rising levels of xenophobia and antisemitism. How survivors have been constructed historically also demonstrates the flawed logic of a historical progressivism within which Holocaust memory is seen to steadily go from silence to interest/increased knowledge. What the research presented in this dissertation shows is that this process is not determined by historical progression but by the underlying problematization of Holocaust survivors’ utility.

     

     

  • Public defence: 2020-03-06 09:00 Granitsalen, Building 448, Entrance 7, Linköping
    Zimdahl, Anna
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Pharmacogenetic studies of thiopurine methyltransferase genotype-phenotype concordance and effect of methotrexate on thiopurine metabolism2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thiopurines (6-mercaptopurine [6-MP], 6-thioguanine and azathioprine) are cytotoxic drugs used in the treatment of acute lymphoblastic leukemia (ALL), inflammatory bowel diseases, certain autoimmune diseases and after transplantation. The metabolism of thiopurines is complex with several enzymes involved in the conversion into active drug metabolites. One of the enzymes, thiopurine methyltransferase (TPMT), is one of the best examples of implemented pharmacogenetics so far. Due to lowered TPMT enzyme activity caused by genetic polymorphism, carriers of heterozygous or homozygous defective TPMT alleles need dose reduction to avoid cytotoxic adverse reactions like myelosuppression or hepatotoxicity if treated with thiopurines.

    To determine TPMT status before the start of treatment, genotyping (for the three most occurring TPMT alleles) and/or phenotyping (TPMT enzyme activity measurements) are used in the clinical setting. In the focus of this thesis, concordance of these methods was investigated in a large cohort of unique samples (n=12,663) collected in the routine analysis service of TPMT status determinations in Linköping. By sequencing all exons in samples where the results of the two methods differed, rare or novel TPMT alleles were discovered. Four TPMT alleles (TPMT*41, *42, *43, *44), not previously described, were characterized in terms of clinical in vivo data as well as protein structure and stability data obtained from recombinant human TPMT (rTPMT) produced by E. Coli and biophysical methods.

    The clinical cohort was also used in the search for other factors (except genetic factors) that influence TPMT enzyme activity, and both age and gender turned out to affect TPMT enzyme activity level. In addition, TPMT enzyme activity in the early treatment of ALL was investigated and shown to be significantly lower at time of ALL diagnosis.

    In the treatment protocol of ALL, the combined treatment using 6-MP and methotrexate (MTX) has increased the positive outcomes since the start in the 1950s. Despite this, the synergistic effect of these drugs is not yet fully understood. To evaluate the effect of MTX on thiopurine metabolism specifically, TPMT enzyme activity, TPMT gene expression, and thiopurine metabolite levels were determined before and after MTX infusions in vivo and after cotreatment in lymphoblasts in vitro. In the presence of MTX, TPMT enzyme activity and metabolite levels decreased, both in vivo and in vitro, although dose- and time-dependent. In addition, MTX bound to rTPMT and caused inhibition of rTPMT enzyme activity.

    The results found in the scope of this thesis may be used for further individualization of thiopurine treatment.

    List of papers
    1. Comprehensive study of thiopurine methyltransferase genotype, phenotype, and genotype-phenotype discrepancies in Sweden
    Open this publication in new window or tab >>Comprehensive study of thiopurine methyltransferase genotype, phenotype, and genotype-phenotype discrepancies in Sweden
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    2019 (English)In: Biochemical Pharmacology, ISSN 0006-2952, E-ISSN 1356-1839, Vol. 164, p. 263-272Article in journal (Refereed) Published
    Abstract [en]

    Thiopurines are widely used in the treatment of leukemia and inflammatory bowel diseases. Thiopurine metabolism varies among individuals because of differences in the polymorphic enzyme thiopurine methyltransferase (TPMT, EC 2.1.1.67), and to avoid severe adverse reactions caused by incorrect dosing it is recommended that the patients TPMT status be determined before the start of thiopurine treatment. This study describes the concordance between genotyping for common TPMT alleles and phenotyping in a Swedish cohort of 12,663 patients sampled before or during thiopurine treatment. The concordance between TPMT genotype and enzyme activity was 94.5%. Compared to the genotype, the first measurement of TPMT enzyme activity was lower than expected for 4.6% of the patients. Sequencing of all coding regions of the TPMT gene in genotype/phenotype discrepant individuals led to the identification of rare and novel TPMT alleles. Fifteen individuals (0.1%) with rare or novel genotypes were identified, and three TPMT alleles (TPMT*42, *43, and *44) are characterized here for the first time. These 15 patients would not have been detected as carrying a deviating TPMT genotype if only genotyping of the most common TPMT variants had been performed. This study highlights the benefit of combining TPMT genotype and phenotype determination in routine testing. More accurate dose recommendations can be made, which might decrease the number of adverse reactions and treatment failures during thiopurine treatment.

    Place, publisher, year, edition, pages
    PERGAMON-ELSEVIER SCIENCE LTD, 2019
    Keywords
    Thiopurine; TPMT; Pharmacogenetics; Genotyping; Individualization
    National Category
    Hematology
    Identifiers
    urn:nbn:se:liu:diva-158047 (URN)10.1016/j.bcp.2019.04.020 (DOI)000469163900023 ()31005613 (PubMedID)
    Note

    Funding Agencies|Swedish Childrens Cancer Foundation; Medical Research Council of Southeast Sweden; Swedish Society of Medicine Linkoping; ostgOtaregionens cancerfond

    Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2020-02-17
    2. One amino acid makes a difference-Characterization of a new TPMT allele and the influence of SAM on TPMT stability
    Open this publication in new window or tab >>One amino acid makes a difference-Characterization of a new TPMT allele and the influence of SAM on TPMT stability
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    2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 46428Article in journal (Refereed) Published
    Abstract [en]

    Thiopurine induced toxicity is associated with defects in the thiopurine methyltransferase (TPMT) gene. TPMT is a polymorphic enzyme, with most of the single nucleotide polymorphisms (SNPs) causing an amino acid change, altering the enzymatic activity of the TPMT protein. In this study, we characterize a novel patient allele c.719A amp;gt; C, named TPMT*41, together with the more common variant *3C c.719A amp;gt; G, resulting in an amino acid shift at tyrosine 240 to serine, p.Y240S and cysteine, p.Y240C respectively. We show that the patient heterozygote for c.719A amp;gt; C has intermediate enzymatic activity in red blood cells. Furthermore, in vitro studies, using recombinant protein, show that TPMT p.Y240S is less stable than both TPMTwt and TPMT p.Y240C. The addition of SAM increases the stability and, in agreement with Isothermal Titration Calorimetry (ITC) data, higher molar excess of SAM is needed in order to stabilize TPMT p.Y240C and TPMT p.Y240S compared to TPMTwt. Molecular dynamics simulations show that the loss of interactions is most severe for Y240S, which agrees with the thermal stability of the mutations. In conclusion, our study shows that SAM increases the stability of TPMT and that changing only one amino acid can have a dramatic effect on TPMT stability and activity.

    Place, publisher, year, edition, pages
    NATURE PUBLISHING GROUP, 2017
    National Category
    Biochemistry and Molecular Biology
    Identifiers
    urn:nbn:se:liu:diva-137842 (URN)10.1038/srep46428 (DOI)000400451400001 ()28462921 (PubMedID)
    Note

    Funding Agencies|LiU Cancer Network; Medical Research Council of Southeast Sweden; Lars Hiertas Memory Foundation; Samariten Foundation; Swedish Society of Medicine Linkoping; Ostgotaregionens Cancerfond; Swedish e-Science Research Center

    Available from: 2017-06-02 Created: 2017-06-02 Last updated: 2020-02-17
    3. Methotrexate binds to recombinant thiopurine S-methyltransferase and inhibits enzyme activity after high-dose infusions in childhood leukaemia
    Open this publication in new window or tab >>Methotrexate binds to recombinant thiopurine S-methyltransferase and inhibits enzyme activity after high-dose infusions in childhood leukaemia
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    2013 (English)In: European Journal of Clinical Pharmacology, ISSN 0031-6970, E-ISSN 1432-1041, Vol. 69, no 9, p. 1641-1649Article in journal (Refereed) Published
    Abstract [en]

    Purpose

    Important drugs in the treatment of childhood acute lymphoblastic leukaemia (ALL) are 6-mercaptopurine (6-MP) and methotrexate (MTX). Thiopurine methyltransferase (TPMT) is a polymorphic enzyme causing variability in 6-MP response and toxicity. The aim of this study was to investigate the fluctuation in TPMT enzyme activity over time and the effect of high-dose MTX infusions on TPMT enzyme activity and 6-MP metabolites in paediatric ALL patients.

    Methods

    Fifty-three children with ALL treated according to the NOPHO-ALL 2000 protocol were included in the study. TPMT enzyme activity was measured at six different times starting from diagnosis until after the end of maintenance treatment. TPMT and 6-MP metabolites were measured before the initiation of high-dose MTX (HD-MTX) infusions and at 66 h post-infusion. The interaction between MTX and TPMT was investigated in vitro using recombinant TPMT protein and a leukaemic cell line.

    Results

    Forty percent of TPMT wild-type individuals had deceptively low TPMT enzyme activity according to genotype at the time of diagnosis. TPMT activity had decreased significantly 66 h after the start of HD-MTX infusions (−9.2 %; p = 0.013). MTX bound to recombinant TPMT protein severely inhibiting TPMT enzyme activity (remaining activity 16 %).

    Conclusions

    Our results show that TPMT genotyping should be performed in children with ALL, since 40 % of the children in our study who carried the wild-type TPMT gene were at risk of initial underdosing of 6-MP in cases where only TPMT enzyme activity was determined. MTX inhibits the TPMT enzyme activity after HD-MTX infusions due to protein binding.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2013
    Keywords
    Leukaemia, 6-mercaptopurine, methotrexate, pharmacogenetics, thiopurine s-methyltransferase
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-80190 (URN)10.1007/s00228-013-1521-9 (DOI)000323429900003 ()
    Available from: 2012-08-22 Created: 2012-08-22 Last updated: 2020-02-17Bibliographically approved
  • Public defence: 2020-03-06 10:15 Ada Lovelace, Building B, Linköping
    Voronov, Sergii
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Machine Learning Models for Predictive Maintenance2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The amount of goods produced and transported around the world each year increases and heavy-duty trucks are an important link in the logistic chain. To guarantee reliable delivery a high degree of availability is required, i.e., avoid standing by the road unable to continue the transport mission. Unplanned stops by the road do not only cost due to the delay in delivery, but can also lead to damaged cargo. Vehicle downtime can be reduced by replacing components based on statistics of previous failures. However, such an approach is both expensive due to the required frequent visits to a workshop and inefficient as many components from the vehicles in the fleet are still operational. A prognostic method, allowing for vehicle individualized maintenance plans, therefore poses a significant potential in the automotive field. The prognostic method estimates component degradation and remaining useful life based on recorded data and how the vehicle has been operated.

    Lead-acid batteries is a part of the electrical power system in a heavy-duty truck, primarily responsible for powering the starter motor but also powering auxiliary units, e.g., cabin heating and kitchen equipment, which makes the battery a vital component for vehicle availability. Developing physical models of battery degradation is a difficult process which requires access to battery health sensing that is not available in the given study as well a detailed knowledge of battery chemistry.

    An alternative approach, considered in this work, is data-driven methods based on large amounts of logged data describing vehicle operation conditions. In the use-case studied, recorded data is not closely related to battery health which makes battery prognostic challenging. Data is collected during infrequent and non-equidistant visits to a workshop and there are complex dependencies between variables in the data. The main aim of this work has been to develop a framework and methods for estimating lifetime of lead-acid batteries using data-driven methods for condition-based maintenance. The methodology is general and can be applicable for prognostics of other components.

    A main contribution of the thesis is development of machine learning models for predictive maintenance, estimating conditional reliability functions, using Random Survival Forests (RSF) and recurrent neural networks (RNN). An important property of the data is that for a specific vehicle there may be multiple data readouts, but also one single data readout which makes predictive modeling challenging and dealing with this situation is discussed for both RSF and neural networks models. Data quality is important when building data-driven models, and here the data is imbalanced since there are few battery failures relative to the number of vehicles. Further, the data includes many uninformative variables and among those that are informative, there are complex dependencies and correlation. Methods for selecting which data features to use in the model in this situation is also a key contribution. When a point estimation of the conditional reliability functions is available, it is of interest to know how uncertain the estimate is as it allows to take quality of the prediction into account when deciding on maintenance actions. A theory for estimating the variance of the RSF predictor is another contribution in the thesis. To conclude, the results show that Long Short-Term Memory networks, which is a type of RNN, is the most suitable for the vehicle operational data and give the best performance among methods evaluated in the thesis.

    List of papers
    1. Heavy-duty truck battery failure prognostics using random survival forests
    Open this publication in new window or tab >>Heavy-duty truck battery failure prognostics using random survival forests
    2016 (English)In: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2016, Vol. 49, no 11, p. 562-569Conference paper, Published paper (Refereed)
    Abstract [en]

    Predicting lead-acid battery failure is important for heavy-duty trucks to avoid unplanned stops by the road. There are large amount of data from trucks in operation, however, data is not closely related to battery health which makes battery prognostic challenging. A new method for identifying important variables for battery failure prognosis using random survival forests is proposed. Important variables are identified and the results of the proposed method are compared to existing variable selection methods. This approach is applied to generate a prognosis model for lead-acid battery failure in trucks and the results are analyzed. (C) 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE BV, 2016
    Keywords
    Battery failure prognosis; Random survival forests; Variable selection
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-132240 (URN)10.1016/j.ifacol.2016.08.082 (DOI)000383464400082 ()
    Conference
    8th IFAC Symposium on Advances in Automotive Control (AAC)
    Available from: 2016-10-24 Created: 2016-10-21 Last updated: 2020-01-24
    2. Variable selection for heavy-duty vehicle battery failure prognostics using random survival forests
    Open this publication in new window or tab >>Variable selection for heavy-duty vehicle battery failure prognostics using random survival forests
    2016 (English)In: PHME 2016 Proceedings of the Third European Conference of the Prognostics and Health Management Society 2016, Bilbao, Spain July 5–8, 2016 / [ed] Ioana Eballard and Anibal Bregon, 2016, p. 649-659Conference paper, Published paper (Refereed)
    Abstract [en]

    Prognostics and health management is a useful tool for more flexible maintenance planning and increased system reliability. The application in this study is lead-acid battery failure prognosis for heavy-duty trucks which is important to avoid unplanned stops by the road. There are large amounts of data available, logged from trucks in operation. However, datais not closely related to battery health which makes battery prognostic challenging. When developing a data-driven prognostics model and the number of available variables is large,variable selection is an important task, since including non-informative variables in the model have a negative impact on prognosis performance. Two features of the dataset has been identified, 1) few informative variables, and 2) highly correlated variables in the dataset. The main contribution is a novel method for identifying important variables, taking these two properties into account, using Random Survival Forests to estimate prognostics models. The result of the proposed method is compared to existing variable selection methods,and applied to a real-world automotive dataset. Prognostic models with all and reduced set of variables are generated and differences between the model predictions are discussed, and favorable properties of the proposed approach are highlighted.

    Keywords
    variable selection, random survival forest, battery failure prognostics
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-131788 (URN)978-1-936263-21-9 (ISBN)
    Conference
    Third European Conference of the Prognostics and Health Management Society 2016, Bilbao, July 5-8, 2016
    Available from: 2016-10-06 Created: 2016-10-06 Last updated: 2020-01-24Bibliographically approved
    3. Data-Driven Battery Lifetime Prediction and Confidence Estimation for Heavy-Duty Trucks
    Open this publication in new window or tab >>Data-Driven Battery Lifetime Prediction and Confidence Estimation for Heavy-Duty Trucks
    2018 (English)In: IEEE Transactions on Reliability, ISSN 0018-9529, E-ISSN 1558-1721, Vol. 67, no 2, p. 623-639Article in journal (Refereed) Published
    Abstract [en]

    Maintenance planning is important in the automotive industry as it allows fleet owners or regular customers to avoid unexpected failures of the components. One cause of unplanned stops of heavy-duty trucks is failure in the lead-acid starter battery. High availability of the vehicles can be achieved by changing the battery frequently, but such an approach is expensive both due to the frequent visits to a workshop and also due to the component cost. Here, a data-driven method based on random survival forest (RSF) is proposed for predicting the reliability of the batteries. The dataset available for the study, covering more than 50 000 trucks, has two important properties. First, it does not contain measurements related directly to the battery health; second, there are no time series of measurements for every vehicle. In this paper, the RSF method is used to predict the reliability function for a particular vehicle using data from the fleet of vehicles given that only one set of measurements per vehicle is available. A theory for confidence bands for the RSF method is developed, which is an extension of an existing technique for variance estimation in the random forest method. Adding confidence bands to the RSF method gives an opportunity for an engineer to evaluate the confidence of the model prediction. Some aspects of the confidence bands are considered: their asymptotic behavior and usefulness in model selection. A problem of including time-related variables is addressed in this paper with the argument that why it is a good choice not to add them into the model. Metrics for performance evaluation are suggested, which show that the model can be used to schedule and optimize the cost of the battery replacement. The approach is illustrated extensively using the real-life truck data case study.

    Place, publisher, year, edition, pages
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
    Keywords
    Battery lifetime prognostics; data-driven prediction; flexible maintenance; infinitesimal jackknife (IJ) confidence bands; reliability
    National Category
    Other Computer and Information Science
    Identifiers
    urn:nbn:se:liu:diva-149358 (URN)10.1109/TR.2018.2803798 (DOI)000433911000015 ()
    Note

    Funding Agencies|Scania CV; FFI (Vehicle Strategic Research and Innovation)

    Available from: 2018-07-02 Created: 2018-07-02 Last updated: 2020-01-24
    4. Lead-acid battery maintenance using multilayer perceptron models
    Open this publication in new window or tab >>Lead-acid battery maintenance using multilayer perceptron models
    2018 (English)In: 2018 IEEE International Conference on Prognostics and Health Management (ICPHM), 2018, p. 1-8Conference paper, Published paper (Refereed)
    Abstract [en]

    Predictive maintenance of components has the potential to significantly reduce costs for maintenance and to reduce unexpected failures. Failure prognostics for heavy-duty truck lead-acid batteries is considered with a multilayer perceptron (MLP) predictive model. Data used in the study contains information about how approximately 46,000 vehicles have been operated starting from the delivery date until the date when they come to the workshop. The model estimates a reliability and lifetime probability function for a vehicle entering a workshop. First, this work demonstrates how heterogeneous data is handled, then the architectures of the MLP models are discussed. Main contributions are a battery maintenance planning method and predictive performance evaluation based on reliability and lifetime functions, a new model for reliability function when its true shape is unknown, the improved objective function for training MLP models, and handling of imbalanced data and comparison of performance of different neural network architectures. Evaluation shows significant improvements of the model compared to more simple, time-based maintenance plans.

    Keywords
    lead acid batteries, neural nets, preventive maintenance, reliability, lead-acid battery maintenance, MLP models, neural network architectures, reliability function, lifetime functions, predictive performance evaluation, battery maintenance planning method, heterogeneous data, lifetime probability function, multilayer perceptron predictive model, heavy-duty truck lead-acid batteries, failure prognostics, predictive maintenance, simple time-based maintenance plans, improved objective function, Batteries, Histograms, Maintenance engineering, Data models, Neural networks, Conferences
    National Category
    Transport Systems and Logistics
    Identifiers
    urn:nbn:se:liu:diva-163289 (URN)10.1109/ICPHM.2018.8448472 (DOI)
    Conference
    2018 IEEE International Conference on Prognostics and Health Management (ICPHM)
    Available from: 2020-01-24 Created: 2020-01-24 Last updated: 2020-01-24Bibliographically approved
  • Public defence: 2020-03-06 10:15 K3, Kåkenhus, Norrköping
    Seitanidou, Maria
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Overcoming Limitations of Iontronic Delivery Devices2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organic electronic devices are considered as one of the best candidates to replace conventional inorganic electronic devices due to their electronic conductive functionality, low-cost production techniques, the ability to tune their optical and electronic properties using organic chemistry, and their mechanical flexibility. Moreover, these systems are ideal for bioelectronic applications due to their softness, biocompatibility, and most importantly, their electronic and ionic transport. Indeed, these materials are compatible with biological tissues and cells improving the signal transduction between electronic devices and electrically excitable cells. As ions serve as one of the primary signal carriers of cells, they can selectively tune a cell’s activity; therefore, an improved interface between electronics and biological systems can offer several advantages in healthcare, e.g. the development of efficient drug delivery devices.  

    The main focus of this thesis is the development of electronic delivery devices. Electrophoretic delivery devices called organic electronic ion pumps (OEIPs) are used to electronically control the delivery of small ions, neurotransmitters, and drugs with high spatiotemporal resolution. This work elucidates the ion transport processes and phenomena that happen in the ion exchange membranes during ion delivery and clarifies which parameters are crucial for the ion transport efficiency of the OEIPs. This thesis shows a systematic investigation of these parameters and indicates new methods and OEIP designs to overcome these challenges. Two novel OEIP designs are developed and introduced in this thesis to improve the local ion transport while limiting side effects. OEIPs based on palladium proton trap contacts can improve the membrane permselectivity and optimize the delivery of γ-aminobutyric acid (GABA) neurotransmitters at low pH while preventing any undesired pH changes from proton transport in the biological systems. And OEIPs based on glass capillary fibers are developed to overcome the limitations of devices on planar substrates, related to more complex and larger biologically relevant ion delivery with low mobility for implantable applications. This design can optimize the transport of ions and drugs such as salicylic acid (SA) at low concentrations and at relatively much higher rates, thereby addressing a wider range of biomedically relevant applications and needs.   

    List of papers
    1. pH Dependence of γ-Aminobutyric Acid Iontronic Transport
    Open this publication in new window or tab >>pH Dependence of γ-Aminobutyric Acid Iontronic Transport
    Show others...
    2017 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 121, no 30, p. 7284-7289Article in journal (Refereed) Published
    Abstract [en]

    The organic electronic ion pump (OEIP) has been developed as an “iontronic” tool for delivery of biological signaling compounds. OEIPs rely on electrophoretically “pumping” charged compounds, either at neutral or shifted pH, through an ion-selective channel. Significant shifts in pH lead to an abundance of H+ or OH–, which are delivered along with the intended substance. While this method has been used to transport various neurotransmitters, the role of pH has not been explored. Here we present an investigation of the role of pH on OEIP transport efficiency using the neurotransmitter γ-aminobutyric acid (GABA) as the model cationic delivery substance. GABA transport is evaluated at various pHs using electrical and chemical characterization and compared to molecular dynamics simulations, all of which agree that pH 3 is ideal for GABA transport. These results demonstrate a useful method for optimizing transport of other substances and thus broadening OEIP applications.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2017
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-139731 (URN)10.1021/acs.jpcb.7b05218 (DOI)000407189200007 ()28741949 (PubMedID)2-s2.0-85026913272 (Scopus ID)
    Note

    Funding agencies: EU Seventh Framework Programme [607896]; Knut and Alice Wallenberg Foundation [2012.0302]; Onnesjo Foundation

    Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2020-02-17Bibliographically approved
    2. Overcoming transport limitations in miniaturized electrophoretic delivery devices
    Open this publication in new window or tab >>Overcoming transport limitations in miniaturized electrophoretic delivery devices
    2019 (English)In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 19, no 8, p. 1427-1435Article in journal (Refereed) Published
    Abstract [en]

    Organic electronic ion pumps (OEIPs) have been used for delivery of biological signaling compounds, at high spatiotemporal resolution, to a variety of biological targets. The miniaturization of this technology provides several advantages, ranging from better spatiotemporal control of delivery to reduced invasiveness for implanted OEIPs. One route to miniaturization is to develop OEIPs based on glass capillary fibers that are filled with a polyelectrolyte (cation exchange membrane, CEM). These devices can be easily inserted and brought into close proximity to targeted cells and tissues and could be considered as a starting point for other fiber-based OEIP and iontronic technologies enabling favorable implantable device geometries. While characterizing capillary OEIPs we observed deviations from the typical linear current-voltage behavior. Here we report a systematic investigation of these irregularities by performing experimental characterizations in combination with computational modelling. The cause of the observed irregularities is due to concentration polarization established at the OEIP inlet, which in turn causes electric field-enhanced water dissociation at the inlet. Water dissociation generates protons and is typically problematic for many applications. By adding an ion-selective cap that separates the inlet from the source reservoir this effect is then, to a large extent, suppressed. By increasing the surface area of the inlet with the addition of the cap, the concentration polarization is reduced which thereby allows for significantly higher delivery rates. These results demonstrate a useful approach to optimize transport and delivery of therapeutic substances at low concentrations via miniaturized electrophoretic delivery devices, thus considerably broadening the opportunities for implantable OEIP applications.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2019
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-157204 (URN)10.1039/c9lc00038k (DOI)000465283700008 ()30875418 (PubMedID)2-s2.0-85064156567 (Scopus ID)
    Note

    Funding Agencies|Swedish Foundation for Strategic Research; Advanced Functional Materials SFO-center at Linkoping University; Onnesjo Foundation; Knut and Alice Wallenberg Foundation

    Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2020-02-17Bibliographically approved
    3. Modulating Inflammation in Monocytes Using Capillary Fiber Organic Electronic Ion Pumps
    Open this publication in new window or tab >>Modulating Inflammation in Monocytes Using Capillary Fiber Organic Electronic Ion Pumps
    Show others...
    2019 (English)In: Advanced Healthcare Materials, ISSN 2192-2640, E-ISSN 2192-2659, Vol. 8, no 19, article id 1900813Article in journal (Refereed) Published
    Abstract [en]

    An organic electronic ion pump (OEIP) delivers ions and drugs from a source, through a charge selective membrane, to a target upon an electric bias. Miniaturization of this technology is crucial and will provide several advantages, ranging from better spatiotemporal control of delivery to reduced invasiveness for implanted OEIPs. To miniaturize OEIPs, new configurations have been developed based on glass capillary fibers filled with an anion exchange membrane (AEM). Fiber capillary OEIPs can be easily implanted in proximity to targeted cells and tissues. Herein, the efficacy of such a fiber capillary OEIP for modulation of inflammation in human monocytes is demonstrated. The devices are located on inflammatory monocytes and local delivery of salicylic acid (SA) is initiated. Highly localized SA delivery results in a significant decrease in cytokine (tumor necrosis factor alpha and interleukin 6) levels after lipopolysaccharide stimulation. The findings-the first use of such capillary OEIPs in mammalian cells or systems-demonstrate the utility of the technology for optimizing transport and delivery of different therapeutic substances at low concentrations, with the benefit of local and controlled administration that limits the adverse effect of oral/systemic drug delivery.

    Place, publisher, year, edition, pages
    WILEY, 2019
    Keywords
    bioelectronics; capillary fibers; cytokines; drug delivery; electrophoresis; inflammation; ion exchange membranes; iontronics; organic electronics
    National Category
    Biophysics
    Identifiers
    urn:nbn:se:liu:diva-161161 (URN)10.1002/adhm.201900813 (DOI)000486128400001 ()31502760 (PubMedID)
    Note

    Funding Agencies|Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [RIT15-0119]; Advanced Functional Materials SFO-Center at Linkoping University; International Interdisciplinary Laboratory for Advanced Functional Materials, Linkopings Universitet; Onnesjo Foundation; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation

    Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2020-02-17
  • Public defence: 2020-03-13 09:00 Hasselquistsalen, Building 511, Linköping
    Israelsson, Johan
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Health, Medicine and Caring Sciences, Division of Nursing Sciences and Reproductive Health.
    Health-related quality of life after cardiac arrest2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Cardiac arrest is a major health problem worldwide. For many of the afflicted, cardiac arrest is the natural end of life. For others, it is an unexpected event suddenly striking in the middle of life. During the last decades, major efforts in treatment have contributed to more people surviving their cardiac arrest. However, previous research has mainly focused on survival, while the knowledge about health-related quality of life in survivors is sparse. Hence, there is a need for more research in order to extend the knowledge about the living situations among survivors and their spouses. For example, factors associated with health-related quality of life are not sufficiently investigated. Knowledge about such factors is important in order to develop interventions and to be able to improve post cardiac arrest care. In addition, existing research shows incongruent results concerning differences in characteristics and survival between men and women. In order to provide equitable care between sexes, further studies are warranted.

    Aim: The overall aim of this thesis was to increase the knowledge of survival and health-related quality of life among people suffering cardiac arrest with focus on sex and other related factors. The specific aims were: to describe in-hospital cardiac arrest events with regard to sex and investigate if sex is associated with survival after controlling for known predictors and interaction effects (study I), to describe health status and psychological distress among in-hospital cardiac arrest survivors in relation to sex (study II), to investigate factors associated with health-related quality of life among cardiac arrest survivors treated with an implantable cardioverter defibrillator in relation to sex, and to compare their health-related quality of life with a general population, (study III) and to investigate if type D personality and perceived control among cardiac arrest survivors and their spouses were associated with their own and their partners’ health-related quality of life (study IV).

    Methods: The general design in all studies (I-IV) was quantitative, cross-sectional and correlational. This thesis is based on four different data collections. Data was systematically collected using national quality registries (I and II) or by sending questionnaires to survivors (III and IV) and their spouses (IV), treated at several different hospitals in Sweden. The sample size varied between 126 and 990 across the studies. The outcomes and explanatory study variables were chosen with respect to Wilson and Cleary’s conceptual model of health-related quality of life. The main outcome variables were survival after resuscitation, survival at hospital discharge, survival at 30 days post cardiac arrest (I), and health-related quality of life measured by the Hospital Anxiety and Depression Scale (II and III) and the EuroQol-5 dimensions (II-IV). In this thesis descriptive and inferential statistics were applied. The main statistics consisted of logistic and linear regression analyses, and structural equation modelling.

    Results: Male sex was associated with a better chance of survival to hospital discharge, but no associations between sex and survival after resuscitation or at 30 days were identified. More men than women received resuscitation attempts when suffering an in-hospital cardiac arrest (study I). Health-related quality of life among most cardiac arrest survivors was good (II-IV), even when compared to a general population (III). However, a significant proportion reported low health status and symptoms of anxiety and depression (II and III). Women reported worse health-related quality of life compared to men, and female sex was associated with poorer health-related quality of life in the multiple regression models (II and III). Several additional factors were identified to be associated with poorer health-related quality of life: being unemployed, having a type D personality, perceiving less control, suffering from more comorbidities and suffering from more ICD-related concerns (III). In addition, older age was associated with poorer (EQ VAS) or better (HADS Anxiety) health-related quality of life, depending of outcome measure (II). Moreover, perceived control and type D personality among the survivors were associated with health-related quality of life among their spouses, but not vice versa.

    Conclusions: Although, sex does not appear to be an important predictor for survival, the difference between men and women regarding the proportion of resuscitation attempts should be further investigated. The majority of survivors and their spouses report good health-related quality of life similar to general populations. However, a substantial proportion suffer from health problems. Since women in general report worse health-related quality of life compared to men a higher proportion of women may be in need of support. Several factors associated with worse health-related quality of life were identified and might be used during follow-up and rehabilitation. For example, identifying type D personality might be important when screening patients at risk for health problems. Perceiving more control could be targeted by health-supportive interventions, for example person-centered care. Healthcare professionals should make efforts to identify survivors at risk of poor health-related quality of life and offer individualized support when needed. Characteristics among survivors were associated with health-related quality of life in their spouses. Including spouses in follow-up care is therefore important. Wilson and Cleary’s conceptual model for health-related quality of life appears to be applicable for choosing outcomes in cardiac arrest research and might be helpful when designing interventions to improve post cardiac arrest care.

    List of papers
    1. Is there a difference in survival between men and women suffering in-hospital cardiac arrest?
    Open this publication in new window or tab >>Is there a difference in survival between men and women suffering in-hospital cardiac arrest?
    2014 (English)In: Heart & Lung, ISSN 0147-9563, E-ISSN 1527-3288, Vol. 43, no 6, p. 510-515Article in journal (Refereed) Published
    Abstract [en]

    Objectives: To describe in-hospital cardiac arrest (CA) events with regard to sex and to investigate if sex is associated with survival. Background: Previous studies exploring differences between sexes are incongruent with regard to clinical outcomes. In order to provide equality and improve care, further investigations into these aspects are warranted. Methods: This registry study included 286 CAs. To investigate if sex was associated with survival, logistic regression analyses were performed. Results: The proportion of CA with a resuscitation attempt compared to CA without resuscitation was higher among men. There were no associations between sex and survival when controlling for previously known predictors and interaction effects. Conclusions: Sex does not appear to be a predictor for survival among patients suffering CA where resuscitation is attempted. The difference regarding proportion of resuscitation attempts requires more attention. It is important to consider possible interaction effects when studying the sex perspective.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Heart arrest; Hospital; Sex; Survival; Predictor
    National Category
    Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-112817 (URN)10.1016/j.hrtlng.2014.05.012 (DOI)000344837600007 ()25005828 (PubMedID)
    Note

    Funding Agencies|county council of Kalmar

    Available from: 2015-01-08 Created: 2014-12-17 Last updated: 2020-02-17Bibliographically approved
    2. Health status and psychological distress among in-hospital cardiac arrest survivors in relation to gender
    Open this publication in new window or tab >>Health status and psychological distress among in-hospital cardiac arrest survivors in relation to gender
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    2017 (English)In: Resuscitation, ISSN 0300-9572, E-ISSN 1873-1570, Vol. 114, p. 27-33Article in journal (Refereed) Published
    Abstract [en]

    Aim: To describe health status and psychological distress among in -hospital cardiac arrest (IHCA) survivors in relation to gender. Methods: This national register study consists of data from follow-up registration of IHCA survivors 3-6 months post cardiac arrest (CA) in Sweden. A questionnaire was sent to the survivors, including measurements of health status (EQ-5D-5L) and psychological distress (HADS). Results: Between 2013 and 2015, 594 IHCA survivors were included in the study. The median values for EQ-5D-5L index and EQVAS among survivors were 0.78 (ql-q3 = 0.67-0.86) and 70 (ql -q3 = 50-80) respectively. The values were significantly lower (p amp;lt; 0.001) in women compared to men. In addition, women reported more problems than men in all dimensions of EQ-5D-5L, except self -care. A majority of the respondents reported no problems with anxiety (85.4%) and/or symptoms of depression (87.0%). Women reported significantly more problems with anxiety (p amp;lt; 0.001) and symptoms of depression (p amp;lt; 0.001) compared to men. Gender was significantly associated with poorer health status and more psychological distress. No interaction effects for gender and age were found. Conclusions: Although the majority of survivors reported acceptable health status and no psychological distress, a substantial proportion reported severe problems. Women reported worse health status and more psychological distress compared to men. Therefore, a higher proportion of women may be in need of support. Health care professionals should make efforts to identify health problems among survivors and offer individualised support when needed. (C) 2017 Elsevier B.V. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER IRELAND LTD, 2017
    Keywords
    Anxiety; Depression; Health status; Heart arrest; Hospitals; Gender
    National Category
    Public Health, Global Health, Social Medicine and Epidemiology
    Identifiers
    urn:nbn:se:liu:diva-138921 (URN)10.1016/j.resuscitation.2017.02.006 (DOI)000402487800021 ()28216089 (PubMedID)
    Note

    Funding Agencies|Swedish Heart and Lung Association; Medical Research Council of Southeast Sweden

    Available from: 2017-06-27 Created: 2017-06-27 Last updated: 2020-02-17
    3. Factors associated with health-related quality of life among cardiac arrest survivors treated with an implantable cardioverter-defibrillator
    Open this publication in new window or tab >>Factors associated with health-related quality of life among cardiac arrest survivors treated with an implantable cardioverter-defibrillator
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    2018 (English)In: Resuscitation, ISSN 0300-9572, E-ISSN 1873-1570, Vol. 132, p. 78-84Article in journal (Refereed) Published
    Abstract [en]

    Aim: To explore factors associated with health-related quality of life (HRQoL) among cardiac arrest (CA) survivors treated with an implantable cardioverter-defibrillator (ICD) in relation to gender, and to compare their HRQoL with a general population. Methods: This cross-sectional study included 990 adults treated with an ICD after suffering CA. All participants received a questionnaire including demographics, comorbidities and instruments to measure HRQoL (EQ-5D-3L and HADS), ICD-related concerns (ICDC), perceived control (CAS), and type D personally (DS-14). HRQoL (EQ-5D-3L) was compared to a general Swedish population, matched for age and gender. Linear regression analyses were used to explore factors associated with HRQoL. Results: The CA survivors reported better HRQoL in EQ index and less pain/discomfort compared to the general population (p amp;lt; 0.001). In contrast, they reported more problems in mobility and usual activities (p amp;lt; 0.01). Problems with anxiety and depression were reported by 15.5% and 7.4% respectively. The following factors were independently associated with all aspects of worse HRQoL: being unemployed, suffering more comorbidity, perceiving less control, and having a type D personally. Further, being female and suffering ICD-related concerns were independently associated with worse HRQoL in three of the four final regression models. Conclusions: This extensive population-based study showed that most CA survivors living with an ICD rate their HRQoL as acceptable. In addition, their HRQoL is similar to a general population. Women reported worse HRQoL compared to men. Several factors associated with HRQoL were identified, and might be used when screening patients for health problems and when developing health promoting interventions.

    Place, publisher, year, edition, pages
    ELSEVIER IRELAND LTD, 2018
    Keywords
    Health-related quality of life; Health status; Psychological distress; Cardiac arrest; Implantable cardioverter-defibrillator; Gender
    National Category
    Public Health, Global Health, Social Medicine and Epidemiology
    Identifiers
    urn:nbn:se:liu:diva-152373 (URN)10.1016/j.resuscitation.2018.09.002 (DOI)000446854900019 ()30201535 (PubMedID)
    Note

    Funding Agencies|Medical Research Council of Southeast Sweden; Swedish Heart and Lung Association

    Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2020-02-17
    4. Dyadic effects of type D personality and perceived control on health-related quality of life in cardiac arrest survivors and their spouses using the actor-partner interdependence model
    Open this publication in new window or tab >>Dyadic effects of type D personality and perceived control on health-related quality of life in cardiac arrest survivors and their spouses using the actor-partner interdependence model
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    2019 (English)In: European Journal of Cardiovascular Nursing, ISSN 1474-5151, E-ISSN 1873-1953, article id UNSP 1474515119890466Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    Background: There is a lack of knowledge about factors associated with health-related quality of life in cardiac arrest survivors and their spouses. In addition, survivors and spouses are likely to affect each others health-related quality of life. Aims: The aim was to investigate if a distressed personality and perceived control among cardiac arrest survivors and their spouses were associated with their own and their partners health-related quality of life. Methods: This dyadic cross-sectional study used the actor-partner interdependence model to analyse associations between a distressed personality (type D personality), perceived control (control attitudes scale), and health-related quality of life (EQ index and EQ visual analogue scale). Results: In total, 126 dyads were included in the study. Type D personality and perceived control in cardiac arrest survivors were associated with their own health-related quality of life. In their spouses, a significant association was found for type D personality but not for perceived control. In addition, type D personality and perceived control in survivors were associated with health-related quality of life in their spouses. Conclusions: Type D personality and perceived control are factors that might be considered during post cardiac arrest, because of the associations with health-related quality of life in survivors and spouses. More research is needed to test psychosocial interventions in the cardiac arrest population in order to improve health-related quality of life.

    Place, publisher, year, edition, pages
    SAGE PUBLICATIONS LTD, 2019
    Keywords
    Heart arrest; survivor; partner; health; quality of life; dyads
    National Category
    Public Health, Global Health, Social Medicine and Epidemiology
    Identifiers
    urn:nbn:se:liu:diva-162500 (URN)10.1177/1474515119890466 (DOI)000498130000001 ()31752502 (PubMedID)
    Note

    Funding Agencies|Swedish Heart and Lung AssociationSwedish Heart-Lung Foundation; Medical Research Council of Southeast Sweden

    Available from: 2019-12-16 Created: 2019-12-16 Last updated: 2020-02-17
  • Public defence: 2020-03-20 10:15 Ada Lovelace, House B, Linköping
    Radnosrati, Kamiar
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Time of Flight Estimation for Radio Network Positioning2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Trilateration is the mathematical theory of computing the intersection of circles. These circles may be obtained by time of flight (ToF) measurements in radio systems, as well as laser, radar and sonar systems. A first purpose of this thesis is to survey recent efforts in the area and their potential for localization. The rest of the thesis then concerns selected problems in new cellular radio standards as well as fundamental challenges caused by propagation delays in the ToF measurements, which cannot travel faster than the speed of light. We denote the measurement uncertainty stemming from propagation delays for positive noise, and develop a general theory with optimal estimators for selected distributions, which can be applied to trilateration but also a much wider class of estimation problems.

    The first contribution concerns a narrow-band mode in the long-term evolution (LTE) standard intended for internet of things (IoT) devices. This LTE standard includes a special position reference signal sent synchronized by all base stations (BS) to all IoT devices. Each device can then compute several pair-wise time differences that correspond to hyperbolic functions. The simulation-based performance evaluation indicates that decent position accuracy can be achieved despite the narrow bandwidth of the channel.

    The second contribution is a study of how timing measurements in LTE can be combined. Round trip time (RTT) to the serving BS and time difference of arrival (TDOA) to the neighboring BS are used as measurements. We propose a filtering framework to deal with the existing uncertainty in the solution and evaluate with both simulated and experimental test data. The results indicate that the position accuracy is better than 40 meters 95% of the time.

    The third contribution is a comprehensive theory of how to estimate the signal observed in positive noise, that is, random variables with positive support. It is well known from the literature that order statistics give one order of magnitude lower estimation variance compared to the best linear unbiased estimator (BLUE). We provide a systematic survey of some common distributions with positive support, and provide derivations and summaries of estimators based on order statistics, including the BLUE one for comparison. An iterative global navigation satellite system (GNSS) localization algorithm, based on the derived estimators, is introduced to jointly estimate the receiver’s position and clock bias.

    The fourth contribution is an extension of the third contribution to a particular approach to utilize positive noise in nonlinear models. That is, order statistics have been employed to derive estimators for a generic nonlinear model with positive noise. The proposed method further enables the estimation of the hyperparameters of the underlying noise distribution. The performance of the proposed estimator is then compared with the maximum likelihood estimator when the underlying noise follows either a uniform or exponential distribution.

    List of papers
    1. Performance of OTDOA Positioning in Narrowband IoT Systems
    Open this publication in new window or tab >>Performance of OTDOA Positioning in Narrowband IoT Systems
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    2017 (English)In: 28th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC): Proceedings, IEEE, 2017Conference paper, Published paper (Refereed)
    Abstract [en]

    Narrowband Internet of Things (NB-IoT) is an emerging cellular technology designed to target low-cost devices, high coverage, long device battery life (more than ten years), and massive capacity. We investigate opportunities for device tracking in NB-IoT systems using Observed Time Difference of Arrival (OTDOA) measurements. Reference Signal Time Difference (RSTD) reports are simulated to be sent to the mobile location center periodically or on an ondemand basis. We investigate the possibility of optimizing the number of reports per minute budget on horizontal positioning accuracy using an on-demand reporting method based on the Signal to Noise Ratio (SNR) of the measured cells received by the User Equipment (UE). Wireless channels are modeled considering multipath fading propagation conditions. Extended Pedestrian A (EPA) and Extended Typical Urban (ETU) delay profiles corresponding to low and high delay spread environments, respectively, are simulated for this purpose. To increase the robustness of the filtering method, measurement noise outliers are detected using confidence bounds estimated from filter innovations.

    Place, publisher, year, edition, pages
    IEEE, 2017
    National Category
    Communication Systems Control Engineering Signal Processing
    Identifiers
    urn:nbn:se:liu:diva-142819 (URN)10.1109/PIMRC.2017.8292365 (DOI)000426970901053 ()978-1-5386-3531-5 (ISBN)978-1-5386-3529-2 (ISBN)
    Conference
    28th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Montreal, QC, Canada, 08-13 October, 2017
    Projects
    Tracking in complex sensor systems, TRAX
    Available from: 2017-11-06 Created: 2017-11-06 Last updated: 2020-02-16
    2. Fusion of TOF and TDOA for 3GPP Positioning
    Open this publication in new window or tab >>Fusion of TOF and TDOA for 3GPP Positioning
    Show others...
    2016 (English)In: Fusion 2016, 19th International Conference on Information Fusion: Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 1454-1460Conference paper, Published paper (Refereed)
    Abstract [en]

    Positioning in cellular networks is often based on mobile-assisted measurements of serving and neighboring base stations. Traditionally, positioning is considered to be enabled when the mobile provides measurements of three different base stations. In this paper, we additionally investigate positioning based on time series of Time Of Flight (TOF) and Time Difference of Arrival (TDOA) measurements gathered from two base stations with known positions, where the specific base stations involved depend on the trajectory of the mobile station.. The set of two base stations is different along the trajectory. Each report contains TOF for the serving base station, and one TDOA measurement for the most favorable neighboring base station relative the serving base station. We derive explicit analytical solution related to the intersection of the absolute distance circle (from TOF) and relative distance hyperbola (from TDOA). We consider both geometric noise-free problem and the more realistic problem with additive noise as delivered in the 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE). Positioning performance is evaluated using the Cramer-Rao lower bound.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-130209 (URN)000391273400193 ()978-0-9964527-4-8 (ISBN)
    Conference
    19th International Conference on Information Fusion, Heidelberg, Germany, July 5-8, 2016
    Projects
    TRAX
    Funder
    EU, FP7, Seventh Framework Programme, 607400
    Available from: 2016-07-15 Created: 2016-07-15 Last updated: 2020-02-16Bibliographically approved
  • Public defence: 2020-03-27 12:35 TemCAS, T-building, Linköping
    Mutter, Amelia
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Multiple Imaginaries of the Fossil Fuel Free Future: Biogas and Electricity in Swedish Urban Transport2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the wake of the climate crisis, it has become increasingly evident that the fossil fuel-based transport system must undergo a global transformation. Numerous renewable fuel alternatives have been suggested, accompanied by imaginaries of how these technologies will contribute to a better future. These imaginaries have a wide-ranging impact because the implementation of each alternative technology will require the build-up of multifarious socio-technical ensembles that support their use. As a result, replacing fossil fuels with these renewable alternatives is likely to be a complex process. This dissertation considers the emergence of two such visions of renewable fuels studying imaginaries of biogas and electricity in the Swedish context. Biogas has a long history of use as a transport fuel in Sweden, where although it makes up a small percentage of total fuel use it also forms the basis of numerous municipal public transport systems. Meanwhile, electric vehicles have become increasingly attractive as more actors subscribe to an imaginary that sees the future of vehicles as shared, autonomous, and electric. This interaction is exemplified in urban public transportation as many municipalities begin to implement electric buses in an attempt to increase energy efficiency and reduce pollution. This thesis follows three case studies where the imaginaries of biogas and electric vehicles interact: urban public transport in the municipalities of Linköping and Malmö, and analysis of a comprehensive national policy document Fossil fuel freedom on the road. It contributes to a wider understanding of how visions can influence obduracy and change of transport alternatives within the wider transformation to a fossil fuel free future.  

    List of papers
    1. Mobilizing sociotechnical imaginaries of fossil-free futures - Electricity and biogas in public transport in Linkoping, Sweden
    Open this publication in new window or tab >>Mobilizing sociotechnical imaginaries of fossil-free futures - Electricity and biogas in public transport in Linkoping, Sweden
    2019 (English)In: Energy Research & Social Science, ISSN 2214-6296, E-ISSN 2214-6326, Vol. 49Article in journal (Refereed) Published
    Abstract [en]

    In response to concerns about climate change and fossil fuel reliance, Swedish national policy has set the ambitious goal of a fossil fuel independent transport fleet by 2030, opening up a widespread debate on renewable fuel choice. Across sectors and regions, this debate inspires competing visions for how this transition can be achieved. Using sociotechnical imaginaries for a theoretical background, this paper will examine two competing visions in the case of urban public transport in Linkoping, Sweden. While the biogas sociotechnical imaginary is based on the socio-material reality of the existing local infrastructure system, the electricity imaginary is gaining widespread support including from national and international interests. Using interviews with fourteen key actors and document analysis, this paper seeks to understand how local actors understand biogas and electric buses as competing technologies and how they mobilize these antagonistic imaginaries in their own visions of the future. Most often, actors mobilize both the biogas and the electric imaginary alongside each other, suggestion an attempt at reconciling them at the local level. This reconciliation sheds light on the challenge of applying national imaginaries to local cases and indicates that the complexity of multi-level systems must be considered in large scale sustainability transitions.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE BV, 2019
    Keywords
    Sociotechnical imaginaries; Biogas; Electric vehicles; Local contexts
    National Category
    Social Sciences Interdisciplinary
    Identifiers
    urn:nbn:se:liu:diva-155537 (URN)10.1016/j.erss.2018.10.025 (DOI)000460444100001 ()
    Note

    Funding Agencies|Biogas Research Center; Linkoping University; Swedish Energy Agency

    Available from: 2019-03-27 Created: 2019-03-27 Last updated: 2020-02-03
    2. Obduracy and Change in Urban Transport: Understanding Competition Between Sustainable Fuels in Swedish Municipalities
    Open this publication in new window or tab >>Obduracy and Change in Urban Transport: Understanding Competition Between Sustainable Fuels in Swedish Municipalities
    2019 (English)In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, SUSTAINABILITY, Vol. 11, no 21, article id 6092Article in journal (Refereed) Published
    Abstract [en]

    Within the renewable transport transition, a number of alternative technologies have emerged creating competing visions of how to reduce fossil fuel dependence. This paper examines the dynamics of competing fuels in two Swedish municipalities where electric buses have emerged, threatening incumbent biogas-based bus systems. While in Linkoping, actors are resistant to the promise of electrification, in Malmo the shift to electrify urban buses has already begun. Here, the theoretical perspectives of obduracy and sociotechnical imaginaries are used to analyze obduracy and change in Linkoping and Malmo, showing how the local contexts of these two municipalities influence obduracy or willingness to change. In Linkoping, perceived connections between the biogas-based bus system and local infrastructures of renewable waste management and organic food production cause actors to place biogas buses at the center of a sustainable future region, while in Malmo linkages to the gas network (which also distributes natural gas) cause actors to question the sustainability of the fuel in use and opens up the city to welcome new electric vehicle tests. These examples show how fuel alternatives interact with each other in the wider renewable energy transition.

    Place, publisher, year, edition, pages
    MDPI, 2019
    Keywords
    obduracy; sociotechnical imaginaries; urban public transport; electric vehicles; biogas
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-162889 (URN)10.3390/su11216092 (DOI)000501205200219 ()2-s2.0-85074853894 (Scopus ID)
    Note

    Funding Agencies|Swedish Energy Agency, Linkoping University

    Available from: 2020-01-02 Created: 2020-01-02 Last updated: 2020-02-03Bibliographically approved
  • Public defence: 2020-03-30 10:15 K1, Kåkenhus, Norrköping
    Gryszel, Maciej
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Organic electronic materials for hydrogen peroxide production2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Hydrogen peroxide (H2O2) is an important oxidant, used in various fields of industry, such as paper manufacturing, production of polymers, detergents, and cosmetics. Considering that the molecule degrades only to H2O and O2, it is regarded as a green chemical. Unfortunately, the incumbent method of H2O2 synthesis, based on anthraquinone oxidation, although efficient, is not environmentally friendly, as it requires fossil fuels and significant energy input. Therefore, there are efforts underway to reduce the ecological impact of hydrogen peroxide production. Some of the most promising approaches involve catalytic reduction of O2 to H2O2 in an aqueous environment. This can be coupled with water oxidation. As the required energy could be delivered in different ways, hydrogen peroxide synthesis can be achieved by electrocatalysis, photoelectrocatalysis, or photocatalysis.

    This thesis explores the possibility of using organic electronic materials as catalysts for H2O2 evolution in oxygenated water solutions. Organic electronics is a field of materials science focused on conducting and semiconducting organic molecules. These materials offer many possible advantages, related to low cost, flexibility, and good optoelectronic properties. Huge progress in the field over the last years led to their commercial applications in e.g. organic light emitting diodes and photovoltaics. Only very recently have organic electronics begun to be considered from the point of view of catalysis.

    In the first two papers, we investigate electrocatalytic activity of an organic pigment (PTCDI) and a conducting polymer (PEDOT) towards oxygen reduction to hydrogen peroxide. Both types of catalysts are chemically stable and able to operate in a wide pH range. In paper 3, we demonstrate that H2O2-evolving photocathodes can be based on an organic PN heterojunction, giving devices of a record-breaking performance. In the first part of paper 4, the same concept was tested for a naturally-occurring semiconductor, eumelanin, leading to a first report of photoelectrocatalytic properties of this material. In the second part of paper 4, as well as in papers 5 and 6, we explore, respectively, photochemical hydrogen peroxide synthesis with eumelanin, organic semiconductors, and organic dyes. We show that the photostability of catalysts is higher for materials with low-lying HOMO level and it can be increased by an addition of a reducing agent to the reaction system. Our findings prove that already existing organic electronic materials can be successfully applied in H2O2 evolution for environmentally friendly chemical synthesis, suggesting their use in harvesting of solar energy and in situ generation of hydrogen peroxide for biomedical applications.

    List of papers
    1. Organic semiconductor perylenetetracarboxylic diimide (PTCDI) electrodes for electrocatalytic reduction of oxygen to hydrogen peroxide
    Open this publication in new window or tab >>Organic semiconductor perylenetetracarboxylic diimide (PTCDI) electrodes for electrocatalytic reduction of oxygen to hydrogen peroxide
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    2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 16, p. 1960-1963Article in journal (Refereed) Published
    Abstract [en]

    Hydrogen peroxide is one of the most important industrial chemicals and there is great demand for the production of H2O2 usingmore sustainable and environmentally benign methods. We show electrochemical production of H2O2 by the reduction of O-2, enabled by an organic semiconductor catalyst, N,N-dimethyl perylenetetracarboxylic diimide (PTCDI). We make PTCDI cathodes that are capable of stable and reusable operation in aqueous electrolytes in a pH range of 1-13 with a catalytic figure of merit as high as 26 kg H2O2 per g catalyst per h. These performance and stability open new avenues for organic small molecule semiconductors as electrocatalysts.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2018
    National Category
    Other Chemistry Topics
    Identifiers
    urn:nbn:se:liu:diva-145755 (URN)10.1039/c7cc08471d (DOI)000425531500005 ()29323369 (PubMedID)
    Note

    Funding Agencies|Wallenberg Center for Molecular Medicine at Linkoping University

    Available from: 2018-03-22 Created: 2018-03-22 Last updated: 2020-02-25
    2. Electrocatalytic Production of Hydrogen Peroxide with Poly(3,4-ethylenedioxythiophene) Electrodes
    Open this publication in new window or tab >>Electrocatalytic Production of Hydrogen Peroxide with Poly(3,4-ethylenedioxythiophene) Electrodes
    Show others...
    2019 (English)In: Advanced Sustainable Systems, ISSN 2366-7486, Vol. 3, no 2, p. 1-6, article id 1800110Article in journal (Refereed) Published
    Abstract [en]

    Electrocatalysis for energy‐efficient chemical transformations is a central concept behind sustainable technologies. Numerous efforts focus on synthesizing hydrogen peroxide, a major industrial chemical and potential fuel, using simple and green methods. Electrochemical synthesis of peroxide is a promising route. Herein it is demonstrated that the conducting polymer poly(3,4‐ethylenedioxythiophene), PEDOT, is an efficient and selective heterogeneous catalyst for the direct reduction of oxygen to hydrogen peroxide. While many metallic catalysts are known to generate peroxide, they subsequently catalyze decomposition of peroxide to water. PEDOT electrodes can support continuous generation of high concentrations of peroxide with Faraday efficiency remaining close to 100%. The mechanisms of PEDOT‐catalyzed reduction of O2 to H2O2 using in situ spectroscopic techniques and theoretical calculations, which both corroborate the existence of a chemisorbed reactive intermediate on the polymer chains that kinetically favors the selective reduction reaction to H2O2, are explored. These results offer a viable method for peroxide electrosynthesis and open new possibilities for intrinsic catalytic properties of conducting polymers.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2019
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-163609 (URN)10.1002/adsu.201800110 (DOI)000458426200002 ()
    Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-25Bibliographically approved
    3. Organic heterojunction photocathodes for optimized photoelectrochemical hydrogen peroxide production
    Open this publication in new window or tab >>Organic heterojunction photocathodes for optimized photoelectrochemical hydrogen peroxide production
    2018 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 48, p. 24709-24716Article in journal (Refereed) Published
    Abstract [en]

    Solar-to-chemical conversion of sunlight into hydrogen peroxide as a chemical fuel is an emerging carbon-free sustainable energy strategy. The process is based on the reduction of dissolved oxygen to hydrogen peroxide. Only limited amounts of photoelectrode materials have been successfully explored for photoelectrochemical production of hydrogen peroxide. Herein we detail approaches to produce robust organic semiconductor photocathodes for peroxide evolution. They are based on evaporated donor-acceptor heterojunctions between phthalocyanine and tetracarboxylic perylenediimide, respectively. These small molecules form nanocrystalline films with good operational stability and high surface area. We discuss critical parameters which allow fabrication of efficient devices. These photocathodes can support continuous generation of high concentrations of peroxide with faradaic efficiency remaining at around 70%. We find that an advantage of the evaporated heterojunctions is that they can be readily vertically stacked to produce tandem cells which produce higher voltages. This feature is desirable for fabricating two-electrode photoelectrochemical cells. Overall, the photocathodes presented here have the highest performance reported to date in terms of photocurrent for peroxide production. These results offer a viable method for peroxide photosynthesis and provide a roadmap of strategies that can be used to produce photoelectrodes with even higher efficiency and productivity.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2018
    National Category
    Other Chemical Engineering
    Identifiers
    urn:nbn:se:liu:diva-153662 (URN)10.1039/c8ta08151d (DOI)000453550700005 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation; Wallenberg Centre for Molecular Medicine at Linkoping University; Vinnova within the framework of Treesearch.se

    Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2020-02-25
    4. Aqueous photo(electro)catalysis with eumelanin thin films
    Open this publication in new window or tab >>Aqueous photo(electro)catalysis with eumelanin thin films
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    2018 (English)In: Materials Horizons, ISSN 2051-6347, E-ISSN 2051-6355, Vol. 5, no 5, p. 984-990Article in journal (Refereed) Published
    Abstract [en]

    We report that eumelanin, the ubiquitous natural pigment found in most living organisms, is a photocatalytic material. Though the photoconductivity of eumelanin and its photochemical reactions with oxygen have been known for some time, eumelanins have not been regarded as photofaradaic materials. We find that eumelanin shows photocathodic behavior for both the oxygen reduction reaction and the hydrogen evolution reaction. Eumelanin films irradiated in aqueous solutions at pH 2 or 7 with simulated solar light photochemically reduce oxygen to hydrogen peroxide with accompanying oxidation of sacrificial oxalate, formate, or phenol. Autooxidation of the eumelanin competes with the oxidation of donors. Deposition of thin films on electrodes yields photoelectrodes with higher photocatalytic stability compared with the case of pure photocatalysis, implicating the successful extraction of positive charges from the eumelanin layer. These results open up new potential applications for eumelanin as a photocatalytically-active biomaterial, and inform the growing fundamental body of knowledge about the physical chemistry of eumelanins.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2018
    National Category
    Theoretical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-151797 (URN)10.1039/c8mh00715b (DOI)000444245600023 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation; Italian Project RELIGHT [PON02_00556_3306937]

    Available from: 2018-10-04 Created: 2018-10-04 Last updated: 2020-02-25
    5. General Observation of Photocatalytic Oxygen Reduction to Hydrogen Peroxide by Organic Semiconductor Thin Films and Colloidal Crystals
    Open this publication in new window or tab >>General Observation of Photocatalytic Oxygen Reduction to Hydrogen Peroxide by Organic Semiconductor Thin Films and Colloidal Crystals
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    2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 16, p. 13253-13257Article in journal (Refereed) Published
    Abstract [en]

    Low-cost semiconductor photocatalysts offer unique possibilities for industrial chemical transformations and energy conversion applications. We report that a range of organic semiconductors are capable of efficient photocatalytic oxygen reduction to H2O2 in aqueous conditions. These semiconductors, in the form of thin films, support a 2-electron/2-proton redox cycle involving photoreduction of dissolved O-2 to H2O2, with the concurrent photooxidation of organic substrates: formate, oxalate, and phenol. Photochemical oxygen reduction is observed in a pH range from 2 to 12. In cases where valence band energy of the semiconductor is energetically high, autoxidation competes with oxidation of the donors, and thus turnover numbers are low. Materials with deeper valence band energies afford higher stability and also oxidation of H2O to O-2. We found increased H2O2 evolution rate for surfactant-stabilized nanoparticles versus planar thin films. These results evidence that photochemical O-2 reduction may be a widespread feature of organic semiconductors, and open potential avenues for organic semiconductors for catalytic applications.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2018
    Keywords
    photochemistry; photocatalysis; hydrogen peroxide; organic semiconductors; oxygen reduction reaction; photoanodes
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-147927 (URN)10.1021/acsami.8b01295 (DOI)000431150900001 ()29624365 (PubMedID)
    Note

    Funding Agencies|Wallenberg Center for Molecular Medicine at Linkoping University; "Aufbruch Bayern" initiative of the state of Bavaria

    Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2020-02-25
    6. Water-Soluble Organic Dyes as Molecular Photocatalysts for H2O2 Evolution
    Open this publication in new window or tab >>Water-Soluble Organic Dyes as Molecular Photocatalysts for H2O2 Evolution
    2019 (English)In: Advanced Sustainable Systems, ISSN 2366-7486, Vol. 3, no 8, p. 1-9, article id 1900027Article in journal (Refereed) Published
    Abstract [en]

    Photochemical generation of hydrogen peroxide via oxygen reduction is a critical component of emerging sustainable energy conversion concepts. Light‐absorbing semiconductors as well as electrodes modified with sensitizers typically catalyze oxygen photoreduction to hydrogen peroxide. Here, it is reported that, in contrast to these heterogeneous systems, a homogeneous solution of a metal‐free organic dye can perform the whole catalytic cycle of hydrogen peroxide photoevolution itself. This cycle can proceed with simultaneous oxidation of various organic molecules as electron donors, or even water. In the three water‐soluble dyes that are experimented with, photoevolution of peroxide occurs favorably at neutral to basic pH. The reaction is first order with respect to dye concentration, and evidence implicates a single‐electron reduction pathway with superoxide as an intermediate. Photostability of the dyes over time correlates with increased oxidation potential of the molecule. The finding that hydrogen peroxide can be produced in aqueous solution with single fully organic molecules performing the entire photocatalytic cycle creates a new avenue for the peroxide carbon free energy cycle.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2019
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-163617 (URN)10.1002/adsu.201900027 (DOI)000481496000004 ()2-s2.0-85070881425 (Scopus ID)
    Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-25Bibliographically approved
  • Public defence: 2020-04-06 09:15 Nobel, B-huset, Linköping
    Marcus, Carina
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Sensor and Signature Modeling for Aircraft Conceptual Development2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aircraft design process has several phases, the first of which is conceptual design. In this phase, models describing an aircraft concept’s properties are used to evaluate its function and identify designs that meet given requirements. Fighter aircraft are generally expected to be capable of communicating, delivering munitions and gathering data about their environment to gain situational awareness. The ability to avoid detection by hostile sensors can also be important, depending on the aircraft’s role.

    The design process of the aircraft itself has usually focused on an aircraft’s flight performance and ability to carry loads, e.g. munitions and extra fuel. While acceleration, rate of turn, maximum speed, and operational range are important parameters, the success of military missions also depends on sensor capabilities and signature levels. However, sensor installation and signature reduction measures can affect the aircraft and its flight performance. Whether an aircraft concept fulfills the requirements given is evaluated using simulations in appropriate scenarios. The concept’s performance is assessed using models of aircraft properties, weapon properties, sensor capabilities and signature levels. Models of the aircraft properties are usually connected dynamically, and respond to changes in such things as the size of the concept. However, sensor and signature models are often the result of a separate optimization process and are only statically connected to the aircraft model. The complete aircraft model can be improved by introducing sensor and signature models that dynamically describe both their functions, and their impact on the aircraft. Concurrent design of all the aircraft properties may improve the quality of results from scenario simulations. When models used in simulations contain parameters coupled to each other, analysis of the resulting data is particularly important because that is what supports a decision-maker’s design choice.

    Sensor and signature models, in some cases combined with flight performance models, have been used to test methodologies intended for use in conceptual aircraft design. The results show that even seemingly simple models can produce results that can make a significant contribution to the aircraft design process.

    List of papers
    1. Military utility: A proposed concept to support decision-making
    Open this publication in new window or tab >>Military utility: A proposed concept to support decision-making
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    2015 (English)In: Technology in society, ISSN 0160-791X, E-ISSN 1879-3274, Vol. 43, p. 23-32Article in journal (Refereed) Published
    Abstract [en]

    A concept called Military Utility is proposed for the study of the use of technology in military operations. The proposed concept includes a three-level structure representing key features and their detailed components. On basic level the Military Utility of a technical system, to a military actor, in a specific context, is a compound measure of the military effectiveness, of the assessed technical system's suitability to the military capability system and of the affordability. The concept is derived through conceptual analysis and is based on related concepts used in social sciences, the military domain and Systems Engineering. It is argued that the concept has qualitative explanatory powers and can support military decision-making regarding technology in forecasts, defense planning, development, utilization and the lessons learned process. The suggested concept is expected to contribute to the development of the science of Military-Technology and to be found useful to actors related to defense.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Technology, utility, decision-making
    National Category
    Mechanical Engineering
    Research subject
    Systems science for defence and security
    Identifiers
    urn:nbn:se:liu:diva-163641 (URN)10.1016/j.techsoc.2015.07.001 (DOI)000215364900003 ()
    Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-17Bibliographically approved
    2. Balancing the radar and long wavelength infrared signature properties in concept analysis of combat aircraft - A proof of concept
    Open this publication in new window or tab >>Balancing the radar and long wavelength infrared signature properties in concept analysis of combat aircraft - A proof of concept
    2017 (English)In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 71, p. 733-741Article in journal (Refereed) Published
    Abstract [en]

    Designing combat aircraft with high military effectiveness, affordability and military suitability requires balancing the efforts of many engineering disciplines during all phases of the development. One particular challenge is aircraft survivability, the aircrafts ability to avoid or withstand hostile actions. Signature management is one way of increasing the survivability by improving the ability to avoid detection. Here, the long-wave infrared and radar signatures are studied simultaneously in a mission context. By establishing a system of systems approach at mission system level, the risk of sub optimization at a technical level is greatly reduced. A relevant scenario is presented where the aim is to incapacitate an air-defense system using three different tactics: A low-altitude cruise missile option, a low and medium altitude combat aircraft option. The technical sub-models, i.e. the properties of the signatures, the weapons and the sensors are modeled to a level suitable for early concept development. The results from the scenario simulations are useful for a relative comparison of properties. Depending on the situation, first detection is made by either radar or infrared sensors. Although the modeling is basic, the complexity of the infrared signature and detection chain is demonstrated and possible pivot points for the balancing of radar and IR signature requirements are identified. The evaluation methodology can be used for qualitative evaluation of aircraft concepts at different design phases, provided that the technical models are adapted to a suitable level of detail. (C) 2017 Elsevier Masson SAS. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2017
    Keywords
    Radar; Infrared; Signatures; Scenario; Evaluation
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-144148 (URN)10.1016/j.ast.2017.10.022 (DOI)000418313700067 ()
    Note

    Funding Agencies|Saab Aeronautics; Swedish Defence University; Swedish Armed Forces

    Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2020-02-17
    3. Balancing Antenna Performance vs. Radar Cross Section for a Passive Radar-Detecting Sensor on an Aircraft
    Open this publication in new window or tab >>Balancing Antenna Performance vs. Radar Cross Section for a Passive Radar-Detecting Sensor on an Aircraft
    2019 (English)Conference paper, Published paper (Refereed)
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-163593 (URN)10.2514/6.2019-2047 (DOI)
    Conference
    AIAA SciTech'19
    Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-17
    4. Detection Chain Model Designed for Aircraft Concept Development
    Open this publication in new window or tab >>Detection Chain Model Designed for Aircraft Concept Development
    2019 (English)In: Journal of Aircraft, ISSN 0021-8669, E-ISSN 1533-3868, Vol. 56, no 5, p. 1942-1950Article in journal (Refereed) Published
    Abstract [en]

    Simultaneous design of an aircraft and its sensor systems offers advantages over integrating standard sensors because the need for sensor function can be balanced against the integration issues. A model of the detection chain is here defined as mathematical representations of the sensors, the wave propagation, and the signatures of the target. When used in aircraft concept development in a design space exploration context, the model of the detection chain needs to be simple yet detailed enough to sufficiently describe both the sensor performance and the impact it has on the infrastructure of the aircraft. In this paper a detection chain model for radar is introduced. It includes the detection range, search volume, and signature together with implications in terms of the aircraft infrastructure the parameters of mass, the volume, and power and cooling requirements as a function of antenna size. The best choice of radar cannot be determined by the sensor function alone; it has to be evaluated together with the aircraft in tactical simulations in order to obtain the complete picture. The benefits of a larger antenna can, to some degree, be counteracted by the changes to the aircraft that affect its flight performance.

    Place, publisher, year, edition, pages
    AMER INST AERONAUTICS ASTRONAUTICS, 2019
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-161415 (URN)10.2514/1.C034930 (DOI)000489572700017 ()
    Available from: 2019-10-31 Created: 2019-10-31 Last updated: 2020-02-17
    5. Aspects of the design, evaluation and accuracy of airborne sensor clusters using time-difference of arrival
    Open this publication in new window or tab >>Aspects of the design, evaluation and accuracy of airborne sensor clusters using time-difference of arrival
    2019 (English)In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 92, p. 892-900Article in journal (Refereed) Published
    Abstract [en]

    One way of improving situational awareness without increasing the risk of detection is to use passive sensor systems. If this capability is provided by several aircraft in a cluster, which can incorporate small basic sensor platforms, advantages can be gained such as longer baselines and an increased number of sensors in the cluster. In this paper, a methodology is presented that links results from signal processing to a Design Space Exploration, DSE, regarding sensor clusters when designing clusters that can operate both independently and in cooperation with other systems. When using Time-Difference of Arrival, the accuracy of the estimated location of a signal source depends on errors in timing and positioning of the sensors, errors in estimating signal arrival times and number of sensors and their spatial distribution. The Cramer-Rao Lower Bound is used to investigate the accuracy of signal source estimates for five different clusters and two levels of timing and positioning accuracy. The results show that the direction of arrival estimates are more accurate than those for the range. Although more sensors generally increased the accuracy, their spatial distribution and baseline related to the distance to the signal source also influence the quality of the results. The DSE process is supported by the collected presentation of the data regarding the measurement accuracy of the different sensor configurations, incorporating both cluster configuration as well as the positioning and timing. Having readily accessible data, the decision makers can focus on choosing the sensor system that meets the operational needs. (C) 2019 Elsevier Masson SAS. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2019
    Keywords
    Design Space Exploration; TDOA; Accuracy; Passive; Estimation; Source position; Sensor cluster
    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:liu:diva-161194 (URN)10.1016/j.ast.2019.07.025 (DOI)000485852600074 ()
    Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2020-02-17