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Coming dissertations at Uppsala university

  • Novel approaches using electrocardiographic imaging for early detection of ARVC in patients and relatives and symptoms preceding sudden death Author: Varvara Kommata Link: Publication date: 2022-05-23 14:26

    Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is an inherited disease of the myocardium, predominantly affecting the right ventricle (RV). Arrhythmias are common among patients with the disease and Sudden Cardiac Death (SCD) can occur even in early stages. 

    The overall purpose of this thesis was to investigate the effectiveness of new diagnostic methods in detecting early abnormalities in genetically predisposed individuals and to emphasize the importance of early diagnosis. 

    The analysis of body surface mapping (BSM) signals recorded using a 252-lead vest revealed abnormal repolarisation patterns in all ARVC patients, but also in 25% of family members who were carriers of the family pathogenic variant (M-carriers). The abnormal repolarization patterns preceded repolarization abnormalities on 12-leads electrocardiogram (ECG). Depolarization abnormalities were also detected by the analysis of body surface signals. The QRS dispersion calculated by the body surface signals was significantly higher among ARVC patients compared with controls. 20% of M-carriers presented also with a slightly elevated QRS dispersion. ECG based QRS dispersion could not adequately differentiate ARVC patients from controls. Thus, the higher resolution of the BSM system permitted the detection of repolarization and depolarization abnormalities even in early stages of the disease.

    The analysis of reconstructed epicardial signals using Electrocardiographic Imaging (ECGI) revealed terminal ventricular epicardial activation (the last 20msecs) located only in parts of RV, as opposed to controls, where the right ventricular outflow tract (RVOT) and cardiac base (both right and left ventricle) were activated last. The total ventricular activation time and the RV activation time were both longer in ARVC patients, whereas the area activated during the last 20 msecs was smaller. Similar pattern with delayed conduction in limited areas of the RV were also observed in 50% of the M-carriers. This subgroup presented also smaller area of terminal ventricular activation and longer RV activation time, but the total ventricular activation was normal. 

    Through nationwide registries, the first SCD cohort due to ARVC in Sweden was described. Cardiac related symptoms were common (68%) prior to death and 36% of cases had sought medical care the last six months prior to death. A family history of SCD was present in 45% of the cases.  The careful clinical evaluation of young individuals seeking with cardiac related symptoms and the evaluation of both medical and family history is crucial.

    In conclusion, new technologies, using multiple electrodes for the recording of body surface signals and the reconstruction of the epicardial signals have shown promising results in detecting early repolarization and depolarization abnormalities and could facilitate the early diagnosis in M-carriers.

  • Technology in Absentia : A New Materialist Study of Digital Disengagement Author: Cristina Ghita Link: Publication date: 2022-05-23 10:18

    The rhetoric associated with society-wide digitalisation promises benefits such as increased quality of life, democracy, or sustainability, which point towards normative trajectories of increased automation and digitalisation of nearly all aspects of society. Meanwhile, there is evidence of a disenchantment with digital use, forming a movement that challenges the pervasiveness of digital artefacts such as the smartphone. This kind of scepticism towards digital technologies is currently informing and changing how we assume, understand, and conceptualise technology in our professional and private lives, leading to an emerging trend of volitionally reducing or postponing the use of digital devices – a practice often labelled as digital disengagement. In this dissertation the research lens is directed towards how the disengagement from ubiquitous digital devices unfolds and to what results. Thus, it investigates the productive potential of technology intentionally made absent, repositioning the traditional approach of articulating such absence as a deficit.

    Drawing on a new materialist perspective of technology use which combines assemblage theory with agential realism, this dissertation explores the search for meaningful technological encounters through a multi-sited ethnographic approach. More specifically, it combines autoethnography, a diary study, interviews, participatory observations, and netnography in which moments of disconnection are observed in order to understand experiences of digital disengagement at individual and collective levels. 

    Through this lens, the performativity, temporality, and productivity of digital disengagement are made visible and analysed. Results show that digital disengagement is not an insular practice, including in its composition a myriad of external components. Digitalisation is shown to be in direct dialogue with practices of digital disengagement through their mutual dichotomic logics. Further analysis of such dichotomies suggests new manners of engaging with technology in which digital use and non-use are entangled, resulting in a novel type of technology engagement called diffractive digital use

  • New and old materials for permanent magnets based on earth-abundant elements Author: Daniel Hedlund Link: Publication date: 2022-05-23 09:20

    Electrical motors, which find use in e.g. electrical vehicles, require per-manent magnets to function. Comparing ferrite magnets and Nd-based magnets reveals a large difference in their price and performance. During the last decade, gap-magnets, with performance in between ferrites and Nd-based magnets have attracted considerable research interest world-wide due to the “rare-earth crisis”. During this crisis, the price of certain rare-earth elements experienced volatile changes. This thesis deals with materials that could be relevant as gap-magnets. The thesis starts with introducing key properties and constraints relevant for gap-magnets. In the thesis, four different systems were investigated. The four systems show that permanent magnets need to be understood and optimized on three distinct levels, the crystal level, the structural level, and the micro-structural level. They show how old and new materials can potentially be utilized as permanent magnets. Lastly, the thesis ends with an outlook that presents new ideas for finding new permanent magnets. The ideas presented in the outlook are ideas that were not treated in this thesis, and thus may represent new ways for further work in developing materials for gap-magnets.