Skip directly to content

Coming dissertations at Uppsala university

  • Precise Image-Based Measurements through Irregular Sampling Author: Teo Asplund Link: Publication date: 2019-11-13 13:13

    Mathematical morphology is a theory that is applicable broadly in signal processing, but in this thesis we focus mainly on image data. Fundamental concepts of morphology include the structuring element and the four operators: dilation, erosion, closing, and opening. One way of thinking about the role of the structuring element is as a probe, which traverses the signal (e.g. the image) systematically and inspects how well it "fits" in a certain sense that depends on the operator.

    Although morphology is defined in the discrete as well as in the continuous domain, often only the discrete case is considered in practice. However, commonly digital images are a representation of continuous reality and thus it is of interest to maintain a correspondence between mathematical morphology operating in the discrete and in the continuous domain. Therefore, much of this thesis investigates how to better approximate continuous morphology in the discrete domain. We present a number of issues relating to this goal when applying morphology in the regular, discrete case, and show that allowing for irregularly sampled signals can improve this approximation, since moving to irregularly sampled signals frees us from constraints (namely those imposed by the sampling lattice) that harm the correspondence in the regular case. The thesis develops a framework for applying morphology in the irregular case, using a wide range of structuring elements, including non-flat structuring elements (or structuring functions) and adaptive morphology. This proposed framework is then shown to better approximate continuous morphology than its regular, discrete counterpart.

    Additionally, the thesis contains work dealing with regularly sampled images using regular, discrete morphology and weighting to improve results. However, these cases can be interpreted as specific instances of irregularly sampled signals, thus naturally connecting them to the overarching theme of irregular sampling, precise measurements, and mathematical morphology.

  • International large-scale assessments and mathematics textbooks in a curriculum reform process : Changes in lower secondary school algebra in Sweden 1995–2015 Author: Kristina Palm Kaplan Link: Publication date: 2019-11-11 13:12

    Reforming a curriculum entails more than simply launching new steering documents: it includes the development of new materials, evaluation of reform and identification of needs for further action. Drawing from algebra material surrounding the 2011 Swedish curriculum reform, this thesis contributes to understanding the process of curriculum reform concerning mathematics textbooks and international large-scale assessments.

    Two analytical frameworks are applied to algebra tasks in six mathematics textbooks from three series, published in 1995–2015, and algebra items from four consecutive TIMSS tests in 2003, 2007, 2011 and 2015. These frameworks are a Systemic Functional Linguistics-framework based on a social-semiotic perspective and a framework adapted from different views on school algebra. They are used in order to understand algebra characteristics in terms of school algebra discourses and algebraic activities. Additionally, the relationship between Swedish students’ results on TIMSS’ algebra-items and algebra characteristics of the test items is explored statistically. The findings are viewed against the test structure over time.

    The results show that five school algebra discourses are identified in both materials: the symbolic, arithmetical, geometrical, (un)realistic and scientific discourse. However, in the TIMSS tests, a relational discourse was further identified. The materials comprise the same algebraic activities, although in somewhat different proportions. The major change in textbooks is conservative since it is an increase of the (un)realistic discourse, which concerns features that may have been prevalent in the Swedish syllabus already a hundred years ago. This discourse may also be interpreted as a transformation of a reform idea in the syllabus, on mathematical literacy, into quite superficial everyday connections.

    A comparison of the materials show that the algebra characteristic which increases most in textbooks, decreases in TIMSS. Further, students with high achievements on TIMSS perform significantly better on test items with algebra characteristics that decrease in proportion, compared with those which increase in proportion. Relatively seen, the difficulty of the tests for these students thus increases over time. This implies that the validity of interpreting TIMSS results as a knowledge trend is lessened. It is therefore less relevant to use TIMSS results for evaluating and identifying needs for further action. It is suggested that conclusions about student achievements in algebra should not be drawn based on the validity of interpreting and using the aggregate of TIMSS results in mathematics. Also, policy makers should pay more attention to how TIMSS results are used as a base for curricular reform and evaluation.

  • Sequelae after Facial Palsy : Clinical, Anatomical and Electrophysiological Studies Author: David Jensson Link: Publication date: 2019-11-11 08:21

    Background: Sequelae after peripheral facial palsy, which among others include synkinesis, non-functional smile and/or lower lip asymmetry, may be devastating for the patient. Bell’s palsy is the most common form of peripheral facial palsy. 

    Aim: The aim was to study a) frequency and potential predictive factors of synkinesis in Bell’s palsy b) new surgical treatment options after facial nerve injury c) coactivation between muscles innervated by the facial nerve and the most common donor nerves in smile reanimation d) anatomical features of the lower lip depressors. 

    Methods: I: Frequency, severity and early predictors of synkinesis development were studied in 829 Bell’s palsy patients. II and IV: Anatomical technical feasibility of intra-facial nerve transfers was analyzed. V: Anatomical features of lower lip depressor muscles were studied and a literature review for lower lip depressor myectomies was performed. III: Coactivation of muscles innervated by cranial nerves during voluntary facial movements was measured with electromyography. 

    Results: I: In Bell’s palsy, synkinesis frequency was 21.3% at 12-months and Sunnybrook composite score at one month was found to be a good predictor for synkinesis. II and IV: A tension-free oculo-zygomatic and platysma-marginal mandibular nerve transfer was anatomically feasible. Full recovery of the lower lip after platsysma-marginal mandibular nerve transfer was found in a clinical case. III: The masseter muscle had a narrower coactivation pattern compared to the tongue. Bite induced a strong coactivation in the zygomaticus major muscle. V: The width of the depressor labii inferioris was 20 ± 4 mm and the distance from the midline to the lateral muscle border was 32 ± 4 mm. For the depressor anguli oris muscle, the corresponding measurements were 14 ± 3 mm and 54 ± 4 mm. The mean recurrence rate after lower lip myectomy reported in the literature is 21%.  

    Conclusion: I: Synkinesis in Bell’s palsy was 21%. Sunnybrook composite score at one month is a good predictor for synkinesis. II: Oculo-zygomatic nerve transfer may be a suitable technique to reduce eye synkinesis and achieve a stronger smile. III: The narrow coactivation pattern in the masseter muscle may be advantageous for spontaneous smile development. IV: The platysma motor nerve transfer is a feasible procedure and can lead to full recovery in lower lip paralysis. V: Knowledge of the width of the depressor muscles is of importance to ensure complete resection in lower lip myectomy.