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Coming dissertations at Uppsala university

  • On Surgical Treatment of Aortic Pathology Author: Jacob Budtz-Lilly Link: Publication date: 2019-11-26 07:07

    The use of endovascular aneurysm repair (EVAR) in the treatment of abdominal aortic aneurysms has advanced from a premature characterization as a “failed experiment” in early 2000 to the predominant modern method of treatment. Technology has accommodated initial shortcomings, but it has also led to expansions in the treatment of ruptured aneurysms and complex aortic pathologies. The overall aim of this thesis is to characterize the contemporary utilization of endovascular repair in the international setting and to evaluate its expanding use in complex aortic disease treatment.

    Paper I is an analysis of outcomes after intact aneurysm treatment from registries of 12 countries. From 2005 to 2013, and with 83,253 patients included, it was shown that the use of EVAR has increased while, the perioperative mortality has decreased. This was counterbalanced by a worsening mortality for those patients treated with open aortic repair.

    Paper II is an analysis of ruptured aneurysms from the above-mentioned international registries. EVAR is also increasing for these patients, although open repair is still the predominant treatment strategy in most centres. Perioperative mortality was superior for EVAR patients, despite increased age and comorbidities. An association between patient-volume and perioperative mortality could be shown for open repair, but the same could not be demonstrated for EVAR.

    Paper III is an evaluation of the adaptation of a total endovascular approach for the treatment of complex abdominal aortic aneurysms from a single centre. The technical success and midterm mortality, as well as post-operative complications, including spinal ischemia, were similar to those reported from large and multi-centre analyses. Previous studies reveal disparate results for centres performing open complex aortic repair. The results here suggest that a total endovascular approach is feasible for dedicated centres contemplating this strategy.  

    Paper IV is an analysis of multiple pre-, peri-, and post-operative variables documented from complex aneurysm procedures. A relationship between increased complexity and variables such as anaesthesia duration, bleeding, hospital stay, and radiation exposure was found. As patients and their comorbidities increase, a decision to embark on a complex procedure should be made with due diligence to these relationships.

    Paper V is a technical analysis of patients following acute treatment for Type A aortic dissections. Many patients are unfit for open aortic arch repair. Based on current availability of endovascular aortic stentgrafts, it was shown that the majority of patients can be treated endovascularly, while anticipated device improvements should further increase the proportion of eligibility. 

  • Quantifiers and Theories : A Lazy Approach Author: Peter Backeman Link: Publication date: 2019-11-22 13:52

    In this thesis we study Automated Theorem Proving (ATP) as well as Satisfiability Modulo Theories (SMT) and present lazy strategies for improving reasoning within these areas. A lazy strategy works by simplifying a problem, and gradually refines the abstraction only when necessary. Often, a solution can be found without solving the full problem, saving valuable resources. We formulate our contributions within two key challenges in ATP and SMT: theory and quantifier reasoning.Many problems need first-order reasoning modulo a theory, i.e., reasoning where symbols in formulas are interpreted according to some background theory. In software verification, which often involves conditions over machine arithmetic, bit-vectors as well as floating-point numbers play an important role. Finding methods for how to reason with these theories in an efficient manner is therefore an important task. In this thesis we present a lazy method for handling bit-vector constraints as well as bit-vector interpolation, which improves performance and produces simpler interpolants. Moreover, a modular approximation framework is described, which allows for high-level description of lazy strategies applicable to a multitude of theories. Such a strategy is combined with a back-end, creating an approximating SMT solver. We use floating-point arithmetic as an illustrating use case, showing how the lazy strategy can improve the overall efficiency.The quantifier is a language construct which allows for making statements about one or all objects of some universe. However, with great power comes great cost - reasoning with quantifiers is very hard. Many decision problems involving quantifiers are not decidable, e.g., validity of first-order logic. Intricate strategies are needed to handle formulas with quantifiers, especially in combination with theory reasoning. We present a new restricted form of unification, by lazy expansion of the domain of substitution, as well as efficient procedures to solve it. This is incorporated into a complete and sound sequent calculus for the combination of the theory of equality and quantifiers.

  • 'Stay Awhile and Listen' : Understanding the Dynamics of Mediatization, Authority, and Literacy in Swedish Religious Education Author: Maximilian Broberg Link: Publication date: 2019-11-22 12:25

    The aim of this article-based dissertation is to explore the role media play in Swedish Religious Education (RE). The purpose is to study Swedish RE teachers’ practices and how these can be related to various dynamics of mediatization, authority, and literacy. Conducted within the Teaching Religion in Late Modern Sweden project at Uppsala University, this study draws on a national survey, as well as semi-structured interviews and classroom observations with 22 RE teachers. Four specific research questions are posed, each addressed separately in four articles. (1) What kinds of media materials do Swedish RE teachers use in their teaching? (2) What kinds of media dynamics are present in RE classrooms where media materials are used? (3) How can RE teachers’ and students’ engagements with mediated religion be analysed from a multiple media literacies perspective? And, (4) how do RE teachers construct authority on religion in a mediatized situation? The first question is approached through a quantitative analysis of survey material, while the three remaining questions were analysed by the use of qualitative thematic analysis of the observations and interviews. The study finds that RE teachers in Sweden use and relate to various forms of media to a large extent in their daily teaching practices, and that these engagements with mediated religion illustrate the complex balance between the individual agency of the teacher on the one hand, and the media dynamics of amplification, framing and performative agency, and co-structuring, on the other. The teachers’ practices in relation to this are in the study viewed as a form of institutional work that is both caused by, and a contributing factor to, an increased mediatization of contemporary Swedish RE. The findings of the four articles are discussed in light of previous research on mediatization of religion in a Nordic context, specifically with regard to literacy and authority. The author argues that by studying these processes within an educational setting – a context that until recently has been under-explored within mediatization of religion research – the study provides new empirical as well as theoretical knowledge not only to the field of sociology of religion, but also to research on authority and religious education.