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Coming dissertations at Uppsala university

Please note that the date and time given on these pages is the time of electronic publication, and not the date of the public defense. To find the time and venue of the public defense, please follow the link to DiVA of the thesis in question.
  • Valfrihetens geografi och rationella gymnasieval : En experimentell studie om elevers preferenser vid val av skola

    Author: Mikael Thelin
    Publication date: 2019-08-30 13:54

    The increased possibility to choose school and adaption of market mechanisms has created a Swedish upper secondary school market that exhibits spatial variations. However, in the general political and medial debate on choices in the educational sector of today, geography has come to have a hidden place. Based on the rational choice theory, the reform proponents have taken for granted that students’ preferences reflect the quest for the best school of knowledge. Studying students’ preferences is thus central to be able to highlight the importance of the freedom-based reforms in the publicly founded sector.

    The aim of this thesis is to examine students’ preferences for attributes that are central to the choice of upper secondary school. A further purpose is, based on the preferences, to examine the reform-bearing rational choice theory. The empirical data is based on a feasibility study conducted on 587 students in Halmstad and on a larger national study with data from 1440 students. The national study is carried out on 16 different schools, divided into 12 different municipalities.

    The results of the thesis show that the students’ preferences are characterized by both academic and non-academic considerations. In other words, the students’ academic preferences have competition from other, non-academic preferences that also are of importance for the students and therefor affect how attractive a school is considered. Further, there are differences in preference between the students and it is mainly their grades that correlate with these differences. The study also shows that there are small differences between the students’ preferences that can be related to their spatial context.  

    The fact that students’ preferences do not fulfill the expectations in the underlying and reform-bearing theory, raises the question of how the educational producers and the students use choices to design the school market. There is a fundamental positive value in being able to choose and people in general want to be free and self-determined. For both the individual and the knowledge society, it is, however, crucial that the freedom of choice is not used to deselect knowledge. In this context, understanding of students’ preferences is important.

  • Modelling the Molecular World of Electrolytes and Interfaces : Delving into Li-Metal Batteries

    Author: Mahsa Ebadi
    Publication date: 2019-08-30 11:29

    Lithium metal batteries (LMBs) are potential candidates for powering portable electronic devices and for electromobility. However, utilizing the reactive Li metal electrode means tackling serious challenges in terms of safety risks. A better understanding of electrolytes and solid electrolyte interphase (SEI) formation are highly important in order to improve these issues.

    In this thesis, density functional theory (DFT) and molecular dynamics (MD) are used to explore novel electrolyte systems and the interfacial chemistry of electrolyte/Li metal surfaces. In the first part, the electronic structure and possible decompositions pathways of organic carbonates at the Li metal surface are investigated, which provide information about initial SEI formation. Computed X-ray photoelectron spectroscopy (XPS) for these interfacial compounds is used as a tool to find likely electrolyte decomposition pathways and are supported by direct comparison with the experimental results. The electronic structure and computed XPS spectra of electrolyte solvents and the LiNO3 additive on Li metal by DFT provide atomistic insights into the interphase layer.

    Solid polymer electrolytes (SPEs) are promising electrolytes to be used with the Li metal electrode. In the second part of the thesis, MD simulations of poly(ethylene oxide) (PEO) doped with LiTFSI salt/Li metal interface demonstrate the impact of the surface on the structure and dynamics of the electrolyte. A new interfacial potential model for MD simulations is also developed for the interactions at the SPE/metal interface, which can better capture this chemical interplay. Moreover, the approach to improve the ionic conductivity of SPEs by adding side-chains to the backbone of polymers is scrutinized through MD simulations of the poly(trimethylene carbonate) (PTMC) system. While providing polymer flexibility, a hindering effects of the side-chains on Li+ ion diffusions through reduced coordination site connectivity is observed.

    In the final part, different polymer hosts interacting with Li metal are explored, and rapid decomposition of polycarbonates and polyester on the surface is seen. The complexes of these polymers with LiTFSI and LiFSI showed significant changes in the computed electrochemical stability window and salt degradations. Lastly, Li2O was obtained by DFT calculations as a thermodynamically stable layer on the surface of the Li metal oxidized by PEO.

    The modelling studies performed in this thesis highlight the applicability of these techniques in order to probe the SEI and electrolyte properties in LMBs at the atomistic level.

  • Studies on cysteine-rich peptides from Nemertea and Violaceae : Proteomic and transcriptomic discovery and characterization

    Author: Erik Jacobsson
    Publication date: 2019-08-30 09:06

    The overall aims of the projects included in this thesis were to discover, synthesize and characterize disulphide-stabilized peptides from marine worms (Nemertea sp.) and plants (Viola sp.). 

    One of the main outcomes of this thesis is the discovery of a new family of highly active cysteine-rich toxins, alpha nemertides, from nemertean worms (paper II). Functional characterization and production routes of nemertides were further explored (papers II-III). In addition, 12 new cyclotides from the bog violet were discovered (paper I). Finally, transcriptomes and mucus of the Antarctic nemertean Parborlasia corrugatus were investigated for toxin content (paper IV).

     In paper I wild-type leaf and callus tissue of the endangered bog violet, V. uliginosa, were analyzed using transcriptomics and LC-MS, resulting in the discovery of 12 new cyclotides (i.e. cysteine-rich cyclic peptides). In addition, cyclotide expression under different cell-growth conditions was monitored.

    In paper II  the discovery and initial characterization of a new family of highly active peptides, the alpha nemertides, from the epidermal mucus of the world’s longest animal; Lineus longissimus is described. The most abundant alpha nemertide, alpha-1, was extracted in minute amounts, prompting the use solid phase peptide synthesis (SPPS) for further characterization. The tertiary structure of alpha-1 was elucidated and revealed an inhibitory cystine knot (ICK) framework. The knotted core-structure is similar to the cyclic cystine knot (CCK) motif, found in the cyclotides described in paper I.

    In manuscript III, the production route established in paper II was used to produce nemertides alpha 1-7. These were tested in vivo in an Artemia microwell assay as well as on an extended panel of voltage-gated sodium channels (NaV1.1 – 1.8 and BgNaV1). All seven alpha nemertides were highly active in the in vivo Artemia assay with EC50 values in the sub to low µM range. The alpha nemertides were also active in the NaVs tested. However, differences in the activity profiles were observed, indicating an opportunity for future optimization of alpha nemertides to reach higher specificity to certain NaV subtypes.

    In manuscript IV, the exploration of nemertide toxins was extended to include the Antarctic P. corrugatus. Resulting findings include a set of cysteine-rich peptides, some similar to the nemertides previously discovered in paper II. Two purified peptides and one fraction were evaluated for their membranolytic activity.

  • 7D supersymmetric Yang-Mills theory on toric and hypertoric manifolds

    Author: Andreas Rocén
    Publication date: 2019-08-28 14:14

    This thesis consists of an introduction and three research papers in the general area of geometry and physics. In particular we study 7D supersymmetric Yang-Mills theory and related topics in toric and hypertoric geometry. Yang-Mills theory is used to describe particle interactions in physics but it also plays an important role in mathematics. For example, Yang-Mills theory can be used to formulate topological invariants in differential geometry. In Paper I we formulate 7D maximally supersymmetric Yang-Mills theory on curved manifolds that admit positive Killing spinors. For the case of Sasaki-Einstein manifolds we perform a localisation calculation and find the perturbative partition function of the theory. For toric Sasaki-Einstein manifolds we can write the answer in terms of a special function that count integer lattice points inside a cone determined by the toric action. In Papers II and III we consider 7D maximally supersymmetric Yang-Mills theory on hypertoric 3-Sasakian manifolds. We show that the perturbative partition function can again be formulated in terms of a special function counting integer lattice points in a cone, similar to the toric case. We also present a factorisation result for these functions.

  • Exploration of extended Higgs sectors, development of a displaced track trigger, and improvements in GRID middleware

    Author: Max Isacson
    Publication date: 2019-08-28 14:08

    Two possible solutions to the Standard Model (SM) fine-tuning problem are presented in this thesis, MSSM and Compositeness. The Higgs sector of the MSSM can be tested by searching for charged Higgs bosons. Two direct searches for charged Higgs bosons decaying into a top- and bottom-quark are performed using 13.2 and 36.1 fb–¹ respectively of pp collision data collected at √s = 13 TeV with the ATLAS detector. No significant excess over the SM background is observed and upper limits on σ(pp→tbH+)×B(H+→tb) between 0.07 and 2.9 pb are set at a 95% confidence level in the charged Higgs boson mass range 200–2000 GeV using the CLs method. The phenomenology of a vector-like top-partner decaying into a BSM (pseudo-) scalar is explored and interpreted in 2HDM and Compositeness models. The experimental reach is evaluated using γγ and Zγ final states, and the LHC is determined to be sensitive to top-partner and (pseudo-) scalar masses in the 1–2 TeV range both in the Run 2 and expected Run 3 datasets. Two hardware based hit collection methods targeting long-lived particles are studied for a regional track trigger in anticipation of the HL-LHC upgrade. The efficiency is estimated to be ~20% for a wide range of track parameters for tracks originating from a displaced vertex. The prospect of using GPU-computing on the LHC GRID is considered. Extensions of the ARC middleware Information Providers integrating local GPU information are demonstrated.

  • Mechanical analyses of trabecular bone and its interaction with implants

    Author: Dan Wu
    Publication date: 2019-08-28 13:24

    Bone substitute materials or implants are commonly used in the surgical treatment of bone fractures. However, severe complications are sometimes reported. In order to improve fracture treatment where the interior, porous trabecular bone is involved, it is important to better understand the mechanical properties of this bone and how it interacts with the substitutes/implants, and this was the aim of this thesis.

    Since one of the key mechanical properties of trabecular bone, i.e. the elastic moduli at the tissue level, was not consistently reported in the literature, the results from four widely applied methods were first summarized and presented in a review paper.

    Furthermore, to improve the analysis of the mechanical behavior of bone and its interaction with implants, a new digital volume correlation (DVC) technique was proposed based on higher-order finite elements.

    We further proposed a method to estimate the elastic modulus at the tissue level by compression of single trabeculae within a synchrotron radiation micro-computed tomograph (SRµCT). Full-field displacements were estimated by DVC, which also provided boundary conditions for a finite element model. The proposed method shows potential to estimate trabecular mechanical properties at the tissue level.

    Further, strains and cracks of a trabecular structure under compression till fracture were characterized at the single trabecular level, with DVC applied on high-resolution images from SRµCT.

    The effect of augmentation materials on the engagement of screws inserted into trabecular bone was evaluated in human femoral bone, with and without real-time SRµCT. A newly developed tissue adhesive indicated a potential benefit of this material to the primary implant stability compared to a cement and no augmentation.

    Finally, a trabecular structure of PLA/HA composite material was printed using a fused deposition modelling method as a preliminary step towards better synthetic models of trabecular bone. The synthetic trabecular structure was evaluated using micro-CT, compression and screw pull-out testing.

    In conclusion, methods to estimate strains and mechanical properties of trabecular bone were proposed, insights into interactions between trabecular bone and augmentation/implants were gained, as well as a first step towards a synthetic trabecular model, which may contribute to further mechanical analyses and/or improved clinical treatments of trabecular bone.

  • Brain Structure and Function in Adolescents with Atypical Anorexia Nervosa

    Author: Gaia Olivo
    Publication date: 2019-08-28 08:40

    Atypical anorexia nervosa (AAN) has a high incidence in adolescents, resulting in significant morbidity and mortality. The weight loss is generally less pronounced than that experienced in full-syndrome anorexia nervosa (AN), but the medical consequences can be as severe. Neuroimaging could improve our knowledge regarding the pathogenesis of eating disorders, however research on adolescents is limited, and no neuroimaging studies have been conducted in AAN. In paper I, we investigated brain structure through a voxel-based morphometry analysis in 22 drug-naïve adolescent females newly-diagnosed with AAN, and 38 age- and sex-matched healthy controls. In Paper II, we investigated white matter microstructural integrity on 25 drug-naïve adolescent patients with AAN and 25 healthy controls, using diffusion tensor imaging with a tract-based spatial statistics approach. No differences in brain structure could be detected, indicating preserved regional grey matter volumes and white matter diffusivity in patients with AAN compared to controls. These findings suggest that previous observations of brain structure alterations in full syndrome AN may constitute state-related consequences of severe underweight. Alternatively, the preservation of brain structure might indeed differentiate AAN from AN. In paper III, we investigated resting-state functional connectivity in 22 drug-naïve adolescent patients with AAN, and 24 healthy controls. We report reduced connectivity in patients in brain areas involved in face-processing and social cognition, while an increased connectivity, correlating with depressive symptoms, was found in areas involved in the multimodal integration of sensory stimuli, aesthetic judgment, and social rejection anxiety. These findings point toward a core role for an altered development of socio-emotional skills in the pathogenesis of AAN. In Paper IV, we investigated neural connectivity underlying visual processing of foods with different caloric content in a sample of 28 adolescent females diagnosed with AAN, and 33 age- and sex-matched healthy controls. Our results showed higher connectivity in patients in pathways related to the integration of sensory input and memory retrieval, in response to food with high caloric content. This, however, was coupled to lower connectivity in salience and attentional networks, and lower connectivity between areas involved in visual food cues processing and appetite regulatory regions. Thus, despite food with high caloric content is associated to greater processing of somatosensory information in patients, it is attributed less salience and engages patients’ attention less than food with low caloric content.

  • Water–fat separation in magnetic resonance imaging and its application in studies of brown adipose tissue

    Author: Jonathan Andersson
    Publication date: 2019-08-23 13:12

    Virtually all the magnetic resonance imaging (MRI) signal of a human originates from water and fat molecules. By utilizing the property chemical shift the signal can be separated, creating water- and fat-only images. From these images it is possible to calculate quantitative fat fraction (FF) images, where the value of each voxel is equal to the percentage of its signal originating from fat. In papers I and II methods for water–fat signal separation are presented and evaluated.

    The method in paper I utilizes a graph-cut to separate the signal and was designed to perform well even for a low signal-to-noise ratio (SNR). The method was shown to perform as well as previous methods at high SNRs, and better at low SNRs.

    The method presented in paper II uses convolutional neural networks to perform the signal separation. The method was shown to perform similarly to a previous method using a graph-cut when provided non-undersampled input data. Furthermore, the method was shown to be able to separate the signal using undersampled data. This may allow for accelerated MRI scans in the future.

    Brown adipose tissue (BAT) is a thermogenic organ with the main purpose of expending chemical energy to prevent the body temperature from falling too low. Its energy expending capability makes it a potential target for treating overweight/obesity and metabolic dysfunctions, such as type 2 diabetes. The most well-established way of estimating the metabolic potential of BAT is through measuring glucose uptake using 18F-fludeoxyglucose (18F-FDG) positron emission tomography (PET) during cooling. This technique exposes subjects to potentially harmful ionizing radiation, and alternative methods are desired. One alternative method is measuring the BAT FF using MRI.

    In paper III the BAT FF in 7-year olds was shown to be negatively associated with blood serum levels of the bone-specific protein osteocalcin and, after correction for adiposity, thigh muscle volume. This may have implications for how BAT interacts with both bone and muscle tissue.

    In paper IV the glucose uptake of BAT during cooling of adult humans was measured using 18F-FDG PET. Additionally, their BAT FF was measured using MRI, and their skin temperature during cooling near a major BAT depot was measured using infrared thermography (IRT). It was found that both the BAT FF and the temperature measured using IRT correlated with the BAT glucose uptake, meaning these measurements could be potential alternatives to 18F-FDG PET in future studies of BAT.

  • Immigration: Policies, Mobility, and Integration

    Author: Cristina Bratu
    Publication date: 2019-08-23 11:46

    Essay I: Labor immigration is an important tool that countries can use to address labor shortages. The design of labor immigration policies may affect flows and the composition of immigrant workers, which can, in turn, have an effect on firms and workers in the host country. I quantify such effects by studying a major Swedish reform that made it significantly easier for firms to recruit non-Europeans. Using a difference-in-differences setup, I exploit variation in the strictness of immigration rules which affected industries differentially before and after the reform. Treated industries are predominantly lower-skilled, and concentrated in sectors like hotels and restaurants and retail trade sectors. Using linked employer-employee data, I study the effect of the reform on both firm-level and individual-level outcomes. I find that the mean earnings at firms in treated industries unambiguously increase. Firms also seem to take advantage of skill complementarities between natives and immigrants and intensify their overall hiring of high-skilled workers. Moreover, I follow native incumbents' employment and earnings over time and find heterogeneous effects along the skill and age dimensions.

    Essay II (with Matz Dahlberg, Mattias Engdahl and Till Nikolka): We evaluate the importance of spillover effects of national migration policies by estimating the effect of stricter rules on family reunification in Denmark in 2002 on migration to neighboring countries. We reach two main conclusions. First, we show that stricter rules for reunification lead to a clear and significant increase in emigration of Danish citizens with immigrant background. Most of the emigrants left Denmark for Sweden, a neighboring country in which reunification was possible. Second, we demonstrate that a significant fraction of the individuals that came to Sweden to reunite with a partner left the country again; within two (eight) years around 20% (50%) had left, with the absolute majority leaving for Denmark. Our results indicate that potential spillover effects from national migration policies should be taken into account when forming migration policy.

    Essay III (with Valentin Bolotnyy): We use administrative Swedish data to show that, conditional on parent income, immigrant children have similar incomes and higher educational attainment in adulthood than native-born Swedes. This result, however, masks the fact that immigrant children born into poor families are more likely than similar natives to both reach the top of the income distribution and to stay at the bottom. Immigrant children from high-income families are also more likely than natives to regress to the economic bottom. Notably, however, children from predominantly-refugee sending countries like Bosnia, Syria, and Iran have higher intergenerational mobility than the average immigrant child in Sweden.

    Essay IV (with Valentin Bolotnyy): Home ownership is an important indicator of socio-economic status and a good proxy for wealth. We show that on average, children of immigrants are less likely to own their homes than children of natives at age thirty. The difference remains even after we control for socio-economic characteristics, parental background, and municipality of residence. We find that parental background - both in terms of parents' income and education, but also their own home ownership status - is the most important determinant of home ownership in adulthood. We additionally investigate the role of age at arrival on outcomes in adulthood and find a significant negative effect of age at arrival on income and education, which also translates into a lower probability of owning a home in adulthood. However, growing up in a highly-educated family may partly mitigate this negative effect.

  • Aspects of Coherency in Luke’s Composite Christology

    Author: Daniel Gustafsson
    Publication date: 2019-08-23 11:37

    In presenting the life and teachings of Jesus and his function in salvation history, the authors of the New Testament Gospels employ a variety of motifs and titles drawn from earlier biblical literature as well as various strands of second temple Jewish literature. This study of Luke’s Christology investigates how such motifs merge and intertwine in ways that invite the reader to perceive a measure of coherency among those motifs. 

    Luke’s presentation of Jesus is studied, above all, with tools from narrative criticism. In addition, complementary insights are drawn from Luke’s rewriting of Mark. Previous scholarship has often concluded that Luke employs a variety of christological motifs without having reflected on them or how they may function in relation to each other. Such estimations may, in part, be due to the fact that a narrative approach has not come into focus. The present investigation shows that a narrative approach to Luke’s Christology reveals much in regard to how several christological motifs are integrated with Luke’s overarching narrative. 

    The study first surveys previous scholarly approaches to Luke’s Christology, and thereafter considers second temple Jewish conceptions of eschatological prophets and messiahs. The core of the investigation analyzes four sections in Luke’s Gospel: the infancy narrative (1:26–2:52); Jesus’s proclamation in Nazareth (4:16–30); the end of the travel narrative and Jesus’s triumphal entry into Jerusalem (18:31–19:48), and the passion narrative (22:1–23:49). 

    A central conclusion of the investigation is that detailed attention to features in the narrative – including which characters use a particular christological title, and how it is used – shed new light on how, and to what extent, different motifs merge within Luke. Observations are also made of when different motifs overlap with each other and form clusters with similar meanings. The investigation further identifies some features that are distinct to Luke’s presentation of Jesus. An example of such a feature is that the Holy Spirit is described as a defining factor for the presentation of Jesus as Son of God and Messiah.