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Niðurstöður 1 - 20 af 654

Fluid-rock interaction in the vicinity of felsic and mafic intrusions
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Earth Sciences, 2026-11-13) Pilicita Masabanda, Byron Fabian; Enikő Bali; Faculty of Earth Sciences (UI); Jarðvísindadeild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
This research deals with the thermal and geochemical evolution of the magmatic-hydrothermal transition within the Geitafell Central Volcano (GCV), SE Iceland, to provide critical insights for high-temperature geothermal exploration. By integrating petrography, bulk-rock geochemistry, micro-analytical techniques, and thermal modeling, this study establishes a framework for understanding how intrusions of different sizes drive high-enthalpy systems. The study reveals that geothermal maturation is sustained by a suite of heat sources. Small-scale basaltic dikes (0.5 m thick) generate high-temperature pulses, inducing localized cryptic partial melting (3–10%) and high-grade metamorphism (>800 °C). Although these dikes solidify in less than a day, their thermal impact elevates host-rock temperatures for up to three years; therefore, frequent injections maintain elevated temperatures for several decades. In contrast, the medium-scale (~782 m thick) Hoffell Granite Intrusion (HGI) functions as a sustained heat engine. The HGI formed via extreme fractional crystallization (>95%), where high magmatic halogen concentrations (F, Cl) depressed its solidus; this extended the cooling process and allowed the HGI to remain a viable heat source for over 7000 years. Analysis of quartz-hosted fluid inclusions within the HGI further tracks the chemical transition from metal-rich, salt-saturated magmatic brines to circulating meteoric fluids. Overall, these findings provide evidence of the geodynamic maturation of the GCV, documenting its transition from a rift-axis to a flank-zone environment. This integrated model provides essential tools for identifying deep heat sources and mitigating technical risks, such as halite scaling and chlorine-active corrosion, when drilling into the roots of high-temperature geothermal systems in active volcanic areas.
Mental, physical, and cognitive manifestations of post COVID-19 condition: Evidence from population-based cohorts and national registers
(University of Iceland, School of Health Sciences, Faculty of Medicine, 2026-10) Magnúsdóttir, Ingibjörg; Thor Aspelund; Faculty of Medicine (UI); Læknadeild (HÍ); School of Health Sciences (UI); Heilbrigðisvísindasvið (HÍ)
The global spread of Coronavirus 2019 (COVID-19) has raised concerns about the long-term health consequences among those infected, particularly beyond the acute phase of illness. While a growing number of studies have examined post COVID-19 condition (PCC), much of the existing literature has focused on hospitalised patients or short follow-up periods, often without appropriate comparison groups. Consequently, there remains limited understanding of long-term mental, physical, and cognitive outcomes in the general population and how these outcomes vary according to acute illness severity. The overarching aim of this thesis was to address these gaps by examining long-term health outcomes following COVID-19 across multiple domains using four complementary studies. In Study I, we explored the prevalence of mental health symptoms among individuals diagnosed with COVID-19 compared with those not diagnosed, using multinational cohort data from six countries (Denmark, Estonia, Iceland, Norway, Scotland and Sweden; N=247,249). Individuals with COVID-19 had a higher prevalence of depressive symptoms and poor sleep quality, while no overall increase was observed for anxiety or COVID-19-related distress. A clear gradient by illness severity was identified, with individuals bedridden for seven days or longer showing persistently elevated levels of depressive symptoms, anxiety, and sleep problems up to 16 months after diagnosis. In contrast, individuals never bedridden due to COVID-19 showed similar or lower symptom prevalence compared with those without COVID-19. In Study II, we examined the association between COVID-19 diagnosis and the risk of incident psychiatric disorders and psychotropic medication dispensing, using national register data from Iceland (N=112,159) from February 2020 to February 2022. Individuals diagnosed with COVID-19 had an increased risk of psychiatric disorders and psychotropic medication use compared with those not diagnosed. The associations were strongest for psychotic disorders and substance misuse. Higher risks were observed among individuals that were older, unvaccinated, and with more severe disease. Estimates decreased over time during the study period. In Study III, we investigated the prevalence of long-term physical symptoms following COVID-19 in four Nordic cohorts (N=64,880). Individuals diagnosed with COVID-19 had a higher prevalence of severe physical symptoms compared with those not diagnosed. A strong dose–response relationship was observed, with individuals bedridden for seven days or longer experiencing the highest and most persistent symptom burden up to 27 months after diagnosis. The most commonly reported symptoms included shortness of breath, dizziness, headaches, and low energy or fatigue. In Study IV, we assessed impaired cognitive function among individuals diagnosed with COVID-19 using data from five cohorts (N=153,841). No overall association was observed between COVID-19 diagnosis and impaired cognitive function. However, illness severity was strongly associated with cognitive outcomes, with individuals bedridden for seven days or longer showing a substantially higher prevalence of impaired cognitive function, persisting for up to 32 months after diagnosis. Individuals who were never bedridden showed little to no evidence of increased prevalence. In conclusion, these studies identify long-term adverse outcomes across mental, physical, and cognitive domains, with acute illness severity emerging as a key indicator across all outcomes. Individuals with more severe acute illness experienced a substantial and persistent symptom burden, whereas those in the lowest measured severity categories generally showed little evidence of increased morbidity. However, the results should be interpreted with caution because illness severity was based on self-reported days bedridden in the cohort studies and healthcare utilisation in the register-based study. These findings contribute to a better understanding of PCC and highlight the importance of considering illness severity in future research and clinical practice.
Intermittent Drying of Biomass: A Systematic Reassessment of Energy Efficiency
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, 2026-10-28) Nazemi, Mohiodin; Rúnar Unnþórsson; Faculty of Industrial Engineering, Mechanical Engineering and Computer Science (UI); Iðnaðarverkfræði-, vélaverkfræði- og tölvunarfræðideild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
Drying is one of the most energy-intensive steps in the processing of high-moisture biomass, such as seaweed. In research, intermittent drying has often been reported as more energyefficient than continuous drying. However, the results of previous studies have often not been compared under equivalent conditions, making it unclear whether the reported energy savings stem from genuine advantages of intermittent drying or from methodological artefacts. The objective of this thesis is to systematically reassess the energy efficiency of intermittent drying. The research originated from studies on seaweed pelletization, where it was demonstrated that the majority of the energy in the preprocessing chain was used for drying. Therefore, a new comparison framework was developed to evaluate intermittent and continuous drying under identical operating conditions. A systematic literature review and meta-analysis of published studies were conducted. The reassessment of the results showed that many of the advantages previously attributed to intermittent drying diminish or disappear when the comparison is made on an equivalent basis. Furthermore, the results revealed that material thickness, initial moisture content, and drying temperature are the main parameters influencing the relative performance of the two drying methods. The effects of material thickness and initial moisture content were further investigated through controlled experiments using a porous sponge model, while tests with Bladderwrack were used to evaluate the framework using a representative high-moisture biomass. The results demonstrate that intermittent drying is not inherently energy-efficient; rather, its performance depends on material properties and operating conditions. The benefits of intermittent drying are most likely to occur when internal moisture transport limits the drying process. The thesis establishes a framework for the fair evaluation of intermittent drying and demonstrates that the feasibility of high-moisture biomass utilization depends strongly on drying performance, which is influenced more by material properties and operating conditions than by intermittency itself.
Hauntography: Algorithmic Presence and the Out of Joint in Music AI
(University of Iceland, School of Humanities, Faculty of Icelandic and Comparative Cultural Studies, 2026-10) privato, nicola; Magnússon, Þórhallur; Einarsson, Einar Torfi; Faculty of Icelandic and Comparative Cultural Studies (UI); Íslensku og menningardeild (HÍ); School of Humanities (UI); Hugvísindasvið
Artificial Intelligence (AI) has developed at a rapid pace over the last decade. Accessible computing power and increasingly large datasets, coupled with recent advancements in machine learning techniques, have led to its extensive application in creative domains, including music and the arts. Among AI architectures, the deep learning subset has recently gained prominence. Deep learning models feature multiple processing layers that make them capable of identifying complex statistical patterns in large amounts of data. This architectural complexity makes these systems akin to black boxes, obscuring the processes that lead to the generation of their outputs. For this reason, explainable AI (XAI) has emerged as a prominent field of investigation. While XAI research often focuses on breaking open the AI black box, this dissertation takes a different stance and investigates the creative and epistemological value of AI’s opacity, using it as a theoretical probe to query AI itself. This dissertation asks (i) how the inherent opacity of deep learning systems can come to represent a creative resource, (ii) how this perspective can contribute to reassessing shifting notions of agency, authorship and intentionality in human-AI co-creation, and (iii) how insights from artistic practice may be used to understand the general impact of AI technologies on our society. The dissertation introduces two new interfaces for musical expression (NIMEs) designed to perform with real-time neural audio synthesis (NAS), a deep learning synthesis technique that has recently come to the fore due to its high fidelity and low latency. Three original artistic works based on NAS are then offered and discussed. This corpus, together with works from other artists, is used to answer the first research question, illustrating how artists often leverage AI’s opacity as a creative resource, and increasingly project presences of different kinds onto the hidden layers of AI models. To mobilise the insights from practice and answer the second research question, the dissertation draws on hauntology theory, and through a practice-informed comparative reading of Jacques Derrida and Mark Fisher, develops a framework I term hauntography. Central to this framework are Fisher’s notions of the weird and the eerie, which through Derrida I frame as two co-constitutive modes of phenomena viewed as spectral. Hauntography thus provides an extended vocabulary applicable to creative practice and critical analysis of phenomena from the perspective of epistemological and ontological liminality. To answer the third research question, the theoretical framework is operationalised through thematic analysis of interviews with artists whose practices involve generative AI, and with whom I collaborated during the research. This analysis offers three interrelated insights. First, I observe how AI musical interfaces are often valued by artists insofar as they introduce a weird and eerie perspective on the sonic world represented by the training data. I then develop the notion of spectrophonia to describe how AI outputs bear the deferring traces of the source material, pulverised and reconfigured into something other, yet eerily familiar. Finally, I extend spectrophonia beyond music AI to reflect on AI more broadly. Through a hauntographic reading of Marx, supported by the interviews and by practice, I describe AI as a spectral commodity. While commodities typically conceal the social relations they reify, AI is structurally unable to do so, since these, inscribed in its training data, have to be re-enacted through use.
Enhancing neonatal immune responses with different vaccination strategies: Novel adjuvants and mucosal immunization.
(University of Iceland, School of Health Sciences, Faculty of Medicine, 2026-10) Molina Estupiñan, Jenny Lorena; Stefanía P. Bjarnarson and Ingileif Jónsdóttir; Faculty of Medicine (UI); Læknadeild (HÍ); School of Health Sciences (UI); Heilbrigðisvísindasvið (HÍ)
Vaccination remains a cornerstone of global public health, significantly reducing mortality rates in infants and children. Despite substantial progress, infectious diseases continue to be a leading cause of death for children under five years of age, with 2.3 million fatalities occurring globally in the first month of life in 2022 alone. Many of these infections peak in incidence and severity during early infancy, before routine immunizations are initiated or can provide sufficient protection, highlighting the need for more effective preventive strategies in early life. Neonatal vaccination offers a promising approach by inducing immunity from birth and shortening this vulnerable period, supported by universal healthcare contact at delivery and thus high potential vaccination coverage, particularly in resource-limited settings. An ideal neonatal vaccine would offer a single-dose, needle-free immunization, eliciting immediate and long-lasting protection against multiple diseases. However, neonatal vaccination is challenged by the immaturity of the immune system, characterized by dampened innate responses, a Th2-biased T cell response profile, impaired germinal center (GC) formation, limited plasma cell survival and transient antibody (Ab) production, often resulting in suboptimal and short-lived immunity. Overcoming these limitations could be done with the development of safe and effective adjuvants and optimized immunization routes capable of inducing rapid and durable protective immune responses in early life. The overall aim of this thesis was to investigate how the route of immunization influences neonatal immune responses, with particular emphasis on intranasal (i.n.) versus subcutaneous (s.c.) vaccination, and how novel adjuvants modulate these responses to improve vaccine efficacy. Using a neonatal mouse model, we compared the effects of i.n. and s.c. administration with either mmCT or dmLT formulated with a pneumococcal conjugate vaccine, Pn1-CRM197, on serum Ab levels and Ab-secreting cells (ASCs) in the spleen and bone marrow (BM). Furthermore, we assessed the effects of immunization route, parenteral or mucosal administration, on the induction of B cell survival and activation receptors in the spleen, as well as plasma cell survival factors in the BM. Finally, we evaluated the dose-sparing capacity of the novel adjuvants mmCT, dmLT, CAF01 and CAF08b in comparison with the conventional adjuvant alum (aluminum hydroxide). Our focus was on primary neonatal Ab response, the persistence of ASCs and the protective capacity against two respiratory pathogens, Streptococcus pneumoniae and influenza virus. The results demonstrate that the route of immunization differentially shaped the kinetics of neonatal B cell activation and survival signaling. I.n. immunization induced earlier upregulation of BAFF-R, whereas s.c. immunization promoted earlier TACI expression and BAFF production which occurred at later time point following i.n. immunization, indicating distinct sequential programming of B cell survival and activation pathways. Despite these differences, i.n. and s.c. immunization with Pn1-CRM197 and mmCT or dmLT enhanced GC responses and persistence of vaccine-specific ASCs in BM. Notably, i.n. immunization accelerated plasmablast/plasma cell differentiation, increased BCMA expression, promoted earlier establishment of APRIL-rich BM plasma cell survival niches and enhanced the accumulation of vaccine-specific ASCs in the BM. Thus, these mechanistic changes translated into accelerated and sustained systemic and mucosal Ab responses, including persistent IgA production, while maintaining systemic IgG responses comparable to those induced by s.c. immunization. Together, these findings demonstrate that mucosal immunization accelerates neonatal B cell maturation and the establishment of long-lived humoral immunity by promoting the timely acquisition of key survival signals required for plasma cell differentiation and maintenance. In addition, the novel adjuvants mmCT, dmLT, CAF01 and CAF08b enabled substantial antigen dose sparing while maintaining protective immune responses against both pneumococcal and influenza antigens, although the magnitude of this effect depended on the vaccine. Collectively, this work demonstrates that rational selection of immunization routes and adjuvants can overcome key developmental limitations of neonatal immunity by promoting rapid B cell activation, durable plasma cell survival and long-lasting protective humoral immunity. In particular, i.n. immunization with Pn1-CRM197 and mmCT or dmLT enhanced systemic and mucosal humoral immune responses in the neonatal mouse model, highlighting the potential of mucosal vaccination with appropriate adjuvants as a promising strategy for accelerating protective immune responses early in life while simultaneously inducing systemic and mucosal immunity, providing important mechanistic and translational insights for the development of nextgeneration pediatric vaccines.
Advancing Land-Cover and Land-Use Classification with Semantically Consistent and Data-Efficient Deep Learning on Multi-Source Earth Observation Data
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, 2026-10) Sharma, Surbhi; Prof. Dr. Morris Riedel; Faculty of Industrial Engineering, Mechanical Engineering and Computer Science (UI); Iðnaðarverkfræði-, vélaverkfræði- og tölvunarfræðideild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
Land-use and Land-cover (LULC) mapping from Earth Observation (EO) imagery plays a fundamental role in environmental monitoring, urban planning, agricultural management, and climate change assessment. Recent advances in satellite missions, Machine Learning (ML), Deep Learning (DL), and foundation models have significantly improved large-scale mapping capabilities. However, important challenges remain, including semantic inconsistencies between satellite imagery and in-situ observations, the lack of large-scale benchmark datasets with detailed LULC information for training and evaluating advanced DL models, heterogeneous data sources, mixed pixel effects, limited availability of annotated training data, and the need for computationally scalable processing frameworks. Addressing these challenges requires methodologies that integrate multiple data modalities while improving semantic consistency, data efficiency, and spatial representation. This thesis presents a comprehensive framework for advancing satellite-based LULC mapping through four complementary research directions. First, it investigates the semantic relationship between satellite observations and in-situ field data by leveraging geo-tagged field photographs as an intermediate observational layer. The analysis demonstrates that apparent disagreements between satellite-derived and field-based information often arise not only from limitations of satellite observations but also from ambiguities in field interpretation and inconsistencies in land-cover (LC) taxonomies. Second, the thesis produces the Sen4Map, a large-scale benchmark dataset, integrating Sentinel-2 imagery with harmonized Land Use/Cover Area Frame Survey (LUCAS) field observations and ancillary information. The benchmark provides semantically rich annotations designed to support the development and evaluation of robust DL models for LULC mapping. Third, the thesis develops methods for sub-pixel LULC estimation to capture fine-scale landscape heterogeneity beyond the native spatial resolution of satellite imagery. As a proof of concept, the proposed framework estimates built-up fractions from Sentinel-2 imagery using geospatial foundation model embeddings, demonstrating the potential of pretrained spectral-spatial representations for sub-pixel characterization. And finally, the thesis explores data-efficient learning strategies for EO by investigating few-shot learning with meta-learning on publicly available Remote Sensing (RS) benchmark datasets. These approaches demonstrate improved generalization under limited annotation availability, reducing the dependence on extensive labeled datasets while maintaining competitive mapping performance across diverse environments. Beyond methodological advances, the thesis also contributes scalable computational iii solutions through a Hierarchical Data Format, version 5 (HDF5)-based data architecture optimized for High-Performance Computing (HPC) environments, enabling efficient storage, access, and processing of large multi-source EO datasets. Collectively, the proposed methodologies contribute toward more semantically consistent, data-efficient, and scalable satellite-based LULC mapping systems. As EO transitions toward foundation models, unified embedding representations, and agentic geospatial intelligence, the contributions presented in this thesis establish the datasets, semantic frameworks, and embedding-centric methodologies required to support the next generation of LULC mapping.
Evaluating the Validity of PHQ-9 Scores: A Multi-Method Psychometric Investigation of Sources of Variance Beyond Depression Severity
(University of Iceland, School of Health Sciences, Faculty of Psychology, 2026-10-07) Kristófersdóttir, Kristín Hulda; Fanney Þórsdóttir; Faculty of Psychology (UI); Sálfræðideild (HÍ); School of Health Sciences (UI); Heilbrigðisvísindasvið (HÍ)
The Patient Health Questionnaire-9 (PHQ-9) is one of the most widely used self-report measures of depressive symptoms in clinical practice and research. Its scores are often interpreted as indicators of depression severity, yet this interpretation depends on the extent to which responses reflect depressive symptomatology rather than other influences. The aim of this thesis was to evaluate the validity of PHQ-9 scores by examining sources of variance beyond depression severity that may influence item responses. The thesis comprised four interrelated studies conducted with Icelandic samples. Paper I examined the psychometric properties of an existing Icelandic translation of the PHQ-9 using Mokken scale analysis (MSA) and used cognitive interviews to investigate possible sources of weak item functioning. Paper II introduced a revised Icelandic translation of the PHQ-9 and evaluated its psychometric properties using MSA. Paper III used the method of paired comparisons to examine whether PHQ-9 items differ in their perceived sensitivity, that is, the extent to which respondents experience them as uncomfortable to disclose. Paper IV modeled socially desirable responding as a measured cause of method variance in the PHQ-9 to examine whether it systematically influences item responses and whether that influence varies with item sensitivity. The findings showed that the original Icelandic PHQ-9 had suboptimal scalability and that this was associated with several problems, including translation errors, ambiguous wording, multi-barreled item content, symptom overlap, and other response-process issues. The revised Icelandic translation performed better psychometrically, with stronger scalability and a more coherent ordering of respondents along a depression severity continuum. However, not all problems identified in the original version were resolved. The results further showed that PHQ-9 items differ systematically in perceived sensitivity. Items typically grouped as cognitive/affective were generally judged more uncomfortable to disclose than items grouped as somatic. Finally, socially desirable responding was a source of method variance in PHQ-9 responses, systematically lowering symptom reporting while accounting for considerably less variance than depression severity. This method effect varied across items but did not correspond to their perceived sensitivity. In sum, the findings suggest that PHQ-9 scores may reflect more than depression severity alone. The results support a cautious and context-sensitive interpretation of PHQ-9 sum scores. The PHQ-9 may still be useful as a brief indicator of depressive symptoms, particularly in its revised Icelandic form, but its scores should not be treated as fully transparent or pure measures of depression severity. The thesis underscores the importance of examining how instrument design, item content, translation, and response processes shape the meaning of psychological measurement scores.
Exploring Novel Catalysts for Efficient Electroreduction of CO₂ to e-Fuels
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Physical Sciences, 2026-10-07) Awais, Muhammad; Younes Abghoui; Faculty of Physical Sciences (UI); Raunvísindadeild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
Current global energy and environmental challenges can be viewed as the interaction of three connected factors: the use of fossil fuels, carbon dioxide (CO2) emissions, and global warming. The global energy landscape remains largely dependent on fossil fuels, leading to substantial CO2 emissions and disturbing the climatic equilibrium. Nonetheless, one promising strategy for addressing this challenge is to regard CO2 as a resource, thereby converting the challenge into an opportunity for ecological restoration through the use of CO2 for the production of sustainable fuels. This approach turns CO2 into eco-friendly, value-added compounds, promoting greenhouse gas reduction and sustainable energy development. An effective solution to these limitations can possibly be addressed through chemical physics and electrochemistry, particularly through the implementation of the electrochemical CO2 reduction reaction (CO2RR), which converts CO2 into several single and multi-carbon (C1/C2 products) compounds, including carbon monoxide, formic acid, methanol, methane, methanediol, ethylene, ethane, and ethanol. This process can be readily integrated with current renewable energy infrastructure, enabling the coupling of CO2 conversion with sustainable power sources and therefore storing renewable energy as chemical products. However, their practical application remains limited by the low catalytic activity, poor selectivity, and broad product distribution of conventional metal catalysts. In several instances, these catalysts primarily convert CO2 to only CO or formic acid with relative simplicity, whereas the synthesis of more reduced or multi-carbon compounds requires more energy input and often exhibits restricted efficiency. Hence, the electrochemical CO reduction reaction (CORR) may provide essential solutions to tackle the current challenges in the field of CO2RR. Thus, this Ph.D. thesis is dedicated to the exploration of these two research directions to identify more efficient and selective reaction pathways for sustainable carbon transformation via both CO2RR and CORR. To the best of our knowledge, this thesis presents the first systematic computational investigation of transition metal carbonitrides (TMCNs) for electrochemical CO2RR and CORR. A rigorous computational framework using density functional theory (DFT) within the Vienna Ab initio Simulation Package (VASP) was applied to analyze these surfaces for both CO2RR and CORR. This theoretical study examined 33 different catalytic surfaces, eleven TMCNs in (100), (111), and (110) facets, to predict their catalytic activity towards the formation of C1 and C2 products. Moreover, comprehensive computational evaluations were performed to assess the behavior of these different TMCNs in diverse electrochemical environments with pre-adsorbed CO surface coverage. The catalytic performance was investigated using the conventional and the Mars-van Krevelen (MvK) mechanisms and over 2000 reaction pathways to identify the most thermodynamically favorable routes and predict the best TMCN candidate(s) for efficient carbon conversion and management. In the catalytic activity analysis, TMCN(110) was identified as offering the highest activity for both CO2RR and CORR via the MvK mechanism. In conventional pathways, TMCN(111) was found to be the most active for CO2RR, while TMCN(100) was the best for CORR, and TMCN(111) was inactive toward conventional CORR. Overall, this dissertation provides a comprehensive theoretical assessment of TMCNs and offers computationally grounded predictions for their potential use in converting carbon into green fuels, thereby addressing important environmental and sustainable energy concerns.
Book production in late-fourteenth-century Iceland: A codicological study in the European context
(University of Iceland, School of Humanities, Faculty of Philosophy, History and Archaeology, 2026-07-30) Pokorny, Lea Debora; Beeke Stegmann, Erik Kwakkel; Faculty of Philosophy, History and Archaeology (UI); Deild heimspeki, sagnfræði og fornleifafræði (HÍ); School of Humanities (UI); Hugvísindasvið (HÍ)
The field of Icelandic manuscript studies has become increasingly interested in the material aspects, or codicology, of medieval books, an ongoing trend into which the present study falls. The present thesis aims to contribute to the state of knowledge on vernacular Icelandic manuscript production practice and its organization by centring around the following overarching research questions: (1) How do material characteristics of Icelandic manuscripts dated to the second half of the fourteenth century reflect the methods and practices of their producers? (2) What do observed inconsistencies in codicological features reveal about the resourcefulness, education, and organization of Icelandic book producers? (3) Is it possible to discern to what extent external influences (e.g. other European traditions) shaped production practices of manuscripts in Iceland? At the core of this doctoral thesis stand four peer-reviewed articles and book chapters that address these questions. Two of these were already published by the time of submission, two others have been accepted for publication in peer-reviewed journals. Combined, the four present the data to answer the research questions above. In addition, the introduction to the thesis provides the historical context and methodological framework, while the conclusion puts the findings in the four publications in a broader perspective. To sum up, the results demonstrate that vernacular Icelandic manuscript production during the second half of the fourteenth century utilized a variety of production methods, suggesting that artisans were free to choose which to employ during their work. As such, manuscripts producers in Iceland show inconsistencies in how they proceeded to make handwritten books. The nature of the inconsistencies suggests that the craftsmen aimed to use the resources at their disposal to the fullest, but also that their training was not standardized. Overall, the results speak to a decentralized organization of vernacular book production, which I interpret as “vertical layers”, in which inconsistencies appear to have been the norm, appearing almost naturally as a result of different production practices. While the inconsistencies in production methods can make it challenging to determine the origins of certain practices, there are still clear connections to Insular and the Continental European traditions, demonstrating that Iceland was a sort of “melting pot” of production practices.
Sjóvota skáldið og bókmenntaarfleifð draumsins
(University of Iceland, School of Humanities, Faculty of Icelandic and Comparative Cultural Studies, 2026-09-17) Bjarnason, Bjarni M.; Ástráður Eysteinsson; Íslensku- og menningardeild (HÍ); Faculty of Icelandic and Comparative Cultural Studies (UI); Hugvísindasvið (HÍ); School of Humanities (UI)
Í eftirfarandi doktorsritgerð er gerð grein fyrir örbókmenntagrein í formi frásagnartexta sem finna má í íslenskum þjóðsögum og sögnum. Þessir textar hafa sérstöðu sem mótast af draumljóðum með skilaboðum er virðast berast yfir landamæri lífs og dauða, og raunar er sem vísurnar komi orðréttar frá höfundi sem sjórinn hefur tekið til sín. Þær berast frá honum í djúpinu yfir í draum sofandi einstaklings á þurru landi. Ritgerðin byggir á aðferðum samanburðarbókmennta og eru draumar í völdum heimsbókmenntum rannsakaðir og bornir saman við drauma og draumvísur í íslenskri arfleifð þjóðsagna og sagna. Ritgerðin samanstendur af inngangi og sex köflum. Í innganginum eru settar fram fimm kenningar um hlutverk drauma í bókmenntum og liggja þessar kenningar til grundvallar rannsókninni og rökleiðslu í allri ritgerðinni. Í þeim er meðal annars vikið að því hlutverki drauma að sviðsetja guðlegt umhverfi í bókmenntum og bregða jafnframt svipmóti á persónuleika guðs. Þar eru líka færð fyrir því rök að draumar í bókmenntum gegni tíðum hlutverki tengdu geðhreinsun sem gjarnan á sér stað með guðlegri íhlutun. Í kenningunum er jafnframt fullyrt að hlutverk vísna sjóvota draumskáldsins sé oft tengt sálmum og þjóðtrúarlegri útfærslu á útfararþjónustu eða kveðjuathöfn fyrir látinn einstakling. Að lokum er tekið fram í kenningahlutanum að draumvísur sjóvota draumskáldsins megi líta á sem áfallabókmenntir og þjóðsögurnar og sagnirnar þar sem þær koma fyrir megi rannsaka í tengslum við sorgarviðbrögð aðstandenda drukknaðra sjómanna. Í fyrsta kafla eru færð rök fyrir því að táknmál drauma breytist í takti við menningaraðstæður og hugað er að því hvort og hvernig megi greina á milli raunverulegra draumorða og skáldaðs texta vakandi höfundar. Í öðrum kafla eru draumar í völdum heimsbókmenntum rannsakaðir með áherslu á hlutverk þeirra í söguframvindu sem og í trúarlegu samhengi. Er byrjað á Gilgameskviðu og endað á draumljóðum í íslenskum fornsögum. Í þriðja kafla er menningarlegur jarðvegur draumvísna rannsakaður, og fjallað um bókmenntagreinarnar þjóðsögur og sagnir. Sömuleiðis er í þriðja kafla þjóðtrú rannsökuð sem og trúarlegt hlutverk draumvísna sjóvota draumskáldsins. Í fjórða kafla eru rannsakaðar draumvísur sjóvota skáldsins hjá helstu draumvísnasöfnurum fyrri tíma, þeim Jóni Árnasyni, Sigfúsi Sigfússyni, og Theodóru Thoroddsen, og skilgreind frásagnarformúla þjóðsagna og sagna þar sem draumvísur sjóvota skáldsins koma fyrir. Í fimmta kafla eru tekin saman helstu einkenni þjóðsagna og sagna sem draumvísur sjóvota skáldsins koma fyrir í og rakin bókmenntasaga og rannsóknarsaga þessarar bókmenntagreinar. Hluti af rannsóknarvinnunni fólst í skráningu þessarar örbókmenntagreinar 10 en einnig í víðtækri leit að dæmum um hana. Alls komu 306 draumvísur í leitirnar og í fimmta kafla eru þær staðsettar í 70 heimildum, og þeim síðan raðað í 11 flokka. Í sjötta og síðasta kafla er efnið tekið saman sem og helstu niðurstöður ritgerðarinnar
The Cascading Effects of Policy Reforms: Curriculum, Knowledge and Equal Opportunities
(University of Iceland, School of Education, Faculty of Subject Teacher Education, 2026-10-08) Jónasdóttir, María; Elsa Eiríksdóttir og Guðrún Ragnarsdóttir; Faculty of Subject Teacher Education (UI); Deild faggreinakennslu (HÍ); School of Education (UI); Menntavísindasvið (HÍ)
This thesis examines how recent policy, governance and curriculum reforms have reshaped the conditions under which Icelandic upper secondary academic education operates, and how these changes influence students’ opportunities to access disciplinary knowledge that prepares them for higher education. Focusing on Iceland as a case, the study analyses the effects of decentralisation, competency-based curriculum policy, market-oriented governance and a reform that reduced the time of academic programs from four years to three, on curriculum structures and study pathways. Drawing on critical policy analysis and social realist curriculum theory, the thesis adopts a system-level perspective on curriculum organisation. Rather than examining the content of individual subjects or pedagogy, the analysis focuses on the structural and institutional conditions that shape epistemic access. Using three empirical articles, the study investigates variations in programme structures, credit allocation, levels of advancement, and the availability and stability of progression pathways across school types and locations. The findings reveal substantial structural fragmentation in upper secondary academic education. As responsibility for curriculum-making has been redistributed to individual schools operating under uneven institutional conditions, access to cumulative disciplinary pathways has become increasingly dependent on local capacity, including enrolment size, staffing and funding incentives. These conditions particularly affect subjects organised around hierarchical knowledge structures, such as mathematics and natural sciences, where stable sequencing and progression are essential for cumulative learning, as well as foreign languages. Interpreted through a social realist lens, the findings indicate a weakening of key curriculum principles, including classification, sequencing, and progression. This weakening undermines students’ epistemic access by producing uneven opportunities for cumulative disciplinary learning. From a distributional justice perspective, the study demonstrates that inequality emerges not primarily from individual choice or ability, but from structurally patterned differences in curricular access. The thesis contributes to research on curriculum, education policy and governance, and educational equity by showing how system-level arrangements shape the conditions for disciplinary knowledge. It argues that ensuring equitable preparation for higher education requires renewed attention to curriculum coherence, institutional capacity, and the role of the state in guaranteeing students’ entitlement to knowledge.
Leadership for Social Justice for Immigrant Students and Their Families in Icelandic Schools
(University of Iceland, School of Education, Faculty of Education and Diversity, 2026) Svavarsson, Helgi Þorbjörn; Börkur Hansen; Faculty of Education and Diversity (UI); Deild menntunar og margbreytileika (HÍ); School of Education (UI); Menntavísindasvið (HÍ)
In recent decades, Iceland has undergone significant demographic changes because of increased immigration. The population of Iceland has transitioned from being primarily homogeneous to being multicultural, characterized by diverse languages, customs, and cultural norms. These developments have had a broad impact across all sectors of society, particularly the school system, which has had to adapt to this new reality. Previous research has indicated that despite positive intentions and changes in legislation and curricula, students from immigrant backgrounds do not enjoy the same opportunities as their native peers. They experience higher dropout rates and disadvantages in academic achievement and access to learning opportunities. This doctoral project focuses on leadership in preschools, compulsory schools, and upper-secondary schools with a high proportion of immigrant students that have demonstrated success in advancing social justice. The study aims to highlight the experiences and perspectives of school leaders to identify leadership practices that contribute to the success of these schools. The guiding research question is: What leadership practices can be identified as influential in advancing and sustaining social justice for immigrant students and their families within school communities? Building on critical realism and critical leadership theory, the study employs a multiple case study approach. Data were collected through semi structured interviews with school principals and key staff working with immigrant students in nine schools, three at each educational level. Additional interviews were conducted with preschool parents and compulsory school teachers. The research builds on four publications: three articles and one book chapter. Together, the four publications explore how school leaders in Iceland navigate the interplay between societal structures and leadership agency to promote and sustain social justice for immigrant students. Data were analyzed using framework analysis with different theoretical frameworks applied according to the content of each article, and retroduction analysis to identify underlying forces that promote or hinder social justice. The findings from the four publications are synthesized and examined through the lens of Woods’s (2016) trialectic framework, which is grounded in Archer’s (2003) theory of the interplay between cultural, social, and institutional structures and agency and how these elements influence and shape one another. Woods further distinguished agency into two dimensions: person (individual characteristics) and practice (actions), which together create conditions and possibilities for the leader’s capacity to influence the structures. The study highlights the tension between structural conditions, leadership characteristics, and leadership practices and how they interact to either promote or hinder social justice. The findings indicate that democratic values, ideals of equality, and high levels of societal trust support inclusive leadership, whereas stereotypes about the “normal” student, monolingualism, policy ambiguity, lack of funding, marginalized multicultural teacher education, and negative views of immigrant students function as structural barriers to social justice leadership. The school leaders in this study responded to these barriers by drawing on four core strengths: a strong commitment to social justice, high expectations for all students, an activist mindset, and a pragmatic approach to constraints. Consequently, they worked toward a shared vision by building trust, enhancing staff knowledge and competence in multicultural matters, and creating inclusive learning environments. They employed strategic planning and distributed leadership to engage the school community and address inequities by implementing changes in work practices that reflect student diversity, thereby promoting greater social justice. However, in many cases, this leadership appeared to be highly context-dependent and reliant on individual actors. Moreover, there was a notable lack of formal institutionalization of these practices within the schools’ policies and culture, reducing the likelihood that social justice efforts would be sustained over time. The value of this study lies in its overview of the relationship between societal structures and the promotion of social justice in schools. It highlights the challenges these structures present for school leaders in their efforts to enhance the social and academic positions of immigrant students. This study is part of the Nordic research project Learning Spaces for Inclusion and Social Justice (2013–2015) and is based on empirical data collected during that time. Although the data are not recent, they offer valuable insight into the interaction between structures and agency and into leadership practices within this context, emphasizing the need for further research. Moreover, the findings have practical implications for leadership development and education policy in multicultural contexts.
Nitroxide- and trityl-based polarizing agents for MAS-DNP: Synthesis, mechanistic insights, and applications
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Physical Sciences, 2026-09-14) Chatterjee, Satyaki; Snorri Þór Sigurðsson; Faculty of Physical Sciences (UI); Raunvísindadeild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
Dynamic nuclear polarization (DNP) is a powerful technique for enhancing the sensitivity of nuclear magnetic resonance (NMR) spectroscopy, enabling the investigation of complex materials and biological systems that are otherwise difficult to analyze. In magic-angle spinning (MAS) under solid-state NMR, the cross-effect mechanism employs biradical polarizing agents to transfer electron polarization to surrounding nuclei. However, many polarizing agents remain difficult to synthesize, often suffer from limited aqueous solubility, and the factors governing polarization transfer are not entirely understood. This thesis describes the design, synthesis, and mechanistic investigation of nitroxide- and trityl-based polarizing agents for MAS-DNP. A high-yielding and step-efficient molecular scaffold, AsymPol-Ester, was synthesized as a versatile precursor for developing watersoluble AsymPol-derivatives of both ionic and non-ionic character, functionalized with carboxylate, phosphate, and glucosamine groups. These derivatives were obtained up to seven-fold higher overall yields than previous analogues while maintaining comparable DNP performance. Systematic structural modifications of AsymPols including linker geometry, conformational flexibility and deuteration revealed that DNP efficiency is not only influenced by electron-spin interactions but also by electron-electron coupling. For trityl-nitroxide biradicals, adding spirocycles on nitroxide reduced DNP sensitivity, that benefit bis-nitroxides, unexpectedly revealed a distinct polarization transfer mechanism in trityl-nitroxide biradicals. Further, nuclear-nuclear double resonance (NUDOR) experiments demonstrated that polarization transfer in trityl-nitroxide biradicals is strongly influenced by the large difference in electron-relaxation rates between the two radicals, in contrast to bisnitroxides where electron-electron coupling governs polarization transfer. In addition, tritylnitroxide derivative, TritylTEMPO-X, with six-fold higher aqueous solubility than PyrroTriPol, was synthesized. Finally, application-specific nitroxide radicals were developed for site-directed spin-labeling of biomolecules for local DNP enhancement, and mono-radicals for incorporation into mesoporous organosilica materials.
Redesign of Plastic Packaging for Fresh Fish Transport: Lightweight design based on numerical and experimental investigations of structural and thermal behavior
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, 2026-09-11) LU, ZIWEI; Björn Margeirsson; Fjóla Jónsdóttir; Sigurjón Arason; Ólafur Ögmundarson; Faculty of Industrial Engineering, Mechanical Engineering and Computer Science (UI); Iðnaðarverkfræði-, vélaverkfræði- og tölvunarfræðideild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
The increasing demand for sustainable cold-chain logistics has created a need for lighter and more environmentally efficient packaging for fresh food transport. This thesis investigates the structural, thermal, and environmental performance of expanded polystyrene (EPS) boxes and rotomolded polyethylene (PE) food tubs used in the transport of fresh fish products. The objective is to develop lighter packaging solutions while maintaining the mechanical strength and thermal insulation required for chilled food distribution. The study combines experimental testing, microstructural analysis, finite element analysis (FEA), and life cycle assessment (LCA) to relate material properties to the overall performance of EPS boxes. Experimental results for EPS boxes show that small density variations significantly increase material modulus, and influence the stiffness and stacking strength of the EPS box. Using a calibrated FEA framework, an improved EPS design achieved an 11% reduction in box weight. This reduced the environmental impact across all major LCA categories while causing a 9% reduction in thermal insulation and negligible decrease in stacking strength. For PE food tubs, microstructural defects in the high-density polyethylene (HDPE) skin layer were found to substantially reduce material ductility. Simulations of industrial hoisting conditions further identified buckling of the handle as the dominant failure mode, providing a clear pathway for geometric optimization of load-bearing capacity in the elastic region. Overall, this work provides scientifically validated design guidelines for more sustainable cold-chain packaging and highlights the importance of advanced material models and stochastic numerical methods capable of accounting for the inherent microstructural variability in PE foams.
Heterologous and homologous prime-boost immunization strategies to enhance immune responses in early life
(University of Iceland, School of Health Sciences, Faculty of Medicine, 2026-09-14) Foroutan Pajoohian, Poorya; Stefanía Bjarnarsson; Ingileif Jónsdóttir; Faculty of Medicine (UI); Læknadeild (HÍ); School of Health Sciences (UI); Heilbrigðisvísindasvið (HÍ)
In early life the immune system is characterized by generation of weaker and less durable vaccine-induced antibody responses than in adulthood. This poses a major challenge for the development of vaccines targeting pathogens that require that both strong systemic and mucosal immune responses are elicited to achieve protective immunity. The overall aim of this thesis project was to determine how heterologous prime-boost immunization routes in comparison with the conventional parenteral homologous immunization shape early life humoral immunity to a pneumococcal conjugate vaccine, Pn1-CRM197, and to develop and characterize immunization strategies capable of improving both systemic and mucosal responses in early life. A neonatal mouse model was used in the study. Mice were immunized with Pn1-CRM197 formulated with the adjuvants CAF01 or mmCT for subcutaneous or intranasal administration, respectively. Across this PhD study, vaccine-specific IgG and IgA antibody responses, antibody-secreting cells, germinal center activity, T follicular helper and T follicular regulatory cells, memory B cell generation, plasmablast/plasma cell differentiation and their expression of the survival and activation receptors BAFF-R, TACI and BCMA were examined in spleen, cervical and inguinal lymph nodes and bone marrow. Immunization schedules that included a mucosal administration enhanced vaccinespecific IgA responses in serum and mucosal compartments compared with homologous subcutaneous immunization. However, heterologous subcutaneous priming followed by intranasal booster, while improving mucosal output and generating combined systemic–mucosal responses, did not induce systemic IgG responses comparable to homologous subcutaneous/subcutaneous immunization. Our results showed that the routes of immunizations determined the anatomical site of germinal center induction and shaped the germinal center output. Homologous subcutaneous/subcutaneous immunization preferentially induced germinal center responses in spleen and inguinal lymph nodes, promoted plasmablast/plasma cell differentiation in spleen, increased expression of the survival receptor BCMA on plasma cells in inguinal lymph nodes and yielded high systemic IgG responses. In contrast, heterologous subcutaneous/intranasal immunization redirected the induction of plasmablast/plasma cells responses, BCMA expression toward cervical lymph nodes and favoured the generation of IgM⁺ germinal center-derived memory B cells in all lymphoid organs assessed, and with enhanced BAFF-R and TACI expression, receptor crucial for survival and re-activation, together with stronger IgA responses. The major finding of my study was that reversal of the heterologous immunization schedule, consisting of intranasal priming and subcutaneous booster, successfully overcame the main limitation of the heterologous immunization schedule. It preserved the mucosal advantage of intranasal immunization while inducing systemic IgG responses comparable to homologous subcutaneous/subcutaneous immunization, alongside enhanced serum and salivary IgA responses, increased bone marrow homing of BCMA⁺ plasmablasts/plasma cells, expanded memory B cell output but maintained the favoured generation of IgM⁺ germinal center-derived memory B cells in all lymphoid organs. Together, these studies demonstrate that in early life, the route and order of primeboost immunization affect not only the magnitude, but also the localization and quality of humoral immunity. Among the immunization strategies tested, intranasal priming followed by subcutaneous booster emerged as the most suitable approach, combining robust systemic immunity and mucosal responses, enhanced bone marrow homing of BCMA⁺ plasmablasts/plasma cells and expanded memory B cell output. These findings provide a framework for the rational design of early life vaccination strategies against respiratory pathogens.
Development of a Vibrotactile Wearable for Real-Time Information Communication
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, 2026) Yeganeh, Nashmin; Prof. Dr. Rúnar Unnþórsson; Faculty of Industrial Engineering, Mechanical Engineering and Computer Science (UI); Iðnaðarverkfræði-, vélaverkfræði- og tölvunarfræðideild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
In a digital environment saturated with information, there is an increasing need for new ways to deliver information quickly and reliably without relying on sight or hearing. This is especially critical when these senses are already overloaded or otherwise unavailable. Vibrotactile stimulation, where information is conveyed through vibrations on the skin, shows great promise as a way to utilize the body’s sense of touch. The effectiveness of such systems, however, depends entirely on how the vibrations are structured and calibrated, particularly on regions of the body where the skin is less sensitive. This thesis investigates how to design and fine-tune vibrotactile stimulation in wearable devices so that it communicates information reliably in real-time without causing cognitive fatigue. The forearm is well-suited for such equipment as it does not hinder hand movement and the device can remain nearly unobtrusive. However, the density of mechanoreceptors is lower and spatial perception is poorer there than, for example, in the fingertips, which imposes certain perceptual constraints. Therefore, it is necessary to systematically research how the location, frequency, and temporal patterns of vibration affect how we perceive the vibrations and interpret the messages encoded within them. A custom-built wearable device was designed using voice coil actuators integrated into a flexible textile substrate with 3D-printed enclosures. The device is capable of delivering dynamic, independent, and spatially distributed vibrations. The research employed psychophysical methods to explore and quantify three core dimensions: spatial resolution, frequency effects, and the temporal structure of stimuli. Thesis Objective 1 (TO1) This objective evaluated the minimum spacing required between actuators for users to distinguish between them. The results revealed that a 20 mm spacing yielded the highest accuracy (approximately 90–92%) on both the dorsal and ventral (upper and under) sides of the forearm. Thesis Objective 2 (TO2) This objective investigated how different frequencies (100–250 Hz) and anatomical placements (wrist, mid-forearm, elbow) affected perception. The study showed that frequency alone had little effect, whereas location was crucial; accuracy was higher in areas near landmarks or bone, such as the wrist and elbow. Thesis Objective 3 (TO3) This objective focused on how the timing of stimuli affects perception. Sequential stimulation, where vibration was delivered by one actuator at a time, was compared to simultaneous stimulation, where all relevant actuators were activated at once. The results confirmed that it is significantly easier to distinguish signals delivered sequentially (93.24% accuracy) than those delivered simultaneously (26.15%). Further investigation into inter-stimulus intervals (ISIs) revealed that accuracy is highest when intervals are between 100 and 500 milliseconds. Shorter patterns proved more effective than longer ones, and users remembered the beginning and end of the sequences best. Furthermore, performance improved with practice, demonstrating that users can learn to adapt to such systems over time. These investigations provide a foundation for the design of wearable tactile systems that work efficiently with human perception. The findings are applicable to the development of assistive technologies, sensory substitution devices, silent alerting systems, and even virtual or augmented reality (VR/AR) interfaces. By demonstrating that complex information can be reliably conveyed through structured vibrations on the forearm, this thesis confirms that touch is a viable communication channel in human-computer interaction when other modalities are overloaded.
Life in a cold-water environment: Allometric adaptations of cetaceans in Skjálfandi Bay, Iceland
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Life and Environmental Sciences, 2026-08-28) Glarou, Maria; Marianne H. Rasmussen, Fredrik Christiansen, Takashi Iwata, Arnar Pálsson; Faculty of Life and Environmental Sciences (UI); Líf- og umhverfisvísindadeild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
Energy drives all biological processes and constrains how animals acquire, allocate, and expend resources to maintain fitness. This thesis investigates bioenergetic strategies in sympatric cetaceans inhabiting cold subarctic waters. Focusing on five different-sized species in Skjálfandi Bay, Iceland (harbour porpoises, white-beaked dolphins, minke whales, humpback whales, and blue whales), this study combines UAV photogrammetry and bioenergetic modelling to examine how body size influences heat loss (Article I), field metabolic rate (FMR; Article II), and energetic requirements (Article III) under shared environmental conditions. Heat loss scaled predictably with body size, with absolute heat loss increasing and volume-specific heat loss decreasing across species. Smaller cetaceans exhibited higher surface-area-to-volume ratios (SVR) and therefore higher relative heat loss, partly offset by increased blubber thickness and lower thermal conductivity. In contrast, larger species benefited from reduced SVR and lower relative heat loss. FMR also scaled with body size, with absolute FMR increasing and mass-specific FMR decreasing. Species with higher SVR exhibited higher mass-specific FMR, indicating a correlation between thermoregulatory costs and metabolic scaling. Cetacean FMR estimates were generally higher than predictions for similarly sized terrestrial mammals. Energetic requirements and prey consumption followed the same pattern, with larger species having higher absolute but lower mass-specific requirements. Smaller cetaceans required a greater proportion of their body mass in prey, whereas larger species dominated total prey removal at the population level. Overall, the findings of this thesis show that body size is a primary driver of bioenergetic strategies in cetaceans, shaping their life-history traits and ecological roles.
Melanoma dedifferentiation enhances IFNγ responses and reduces cytotoxic T cell activity
(University of Iceland, School of Health Sciences, Faculty of Medicine, 2026-09) Sævarsson, Teitur; Berglind Ósk Einarsdóttir; Faculty of Medicine (UI); Læknadeild (HÍ); School of Health Sciences (UI); Heilbrigðisvísindasvið (HÍ)
Cutaneous melanoma is a deadly skin cancer arising from epidermal melanocytes. A defining feature of melanoma cells is their ability to reversibly dedifferentiate in response to cellular stress, largely through loss of the transcription factor MITF. Dedifferentiation is associated with reduced melanocytic antigen expression, increased migratory and invasive capacity, altered responses to inflammatory stimuli, e.g. leading to increased IFNγ-induced PD-L1 expression. This indicates that melanoma dedifferentiation may influence anti-tumor immune responses and contribute to immune evasion. In this thesis, the effects of melanoma dedifferentiation on immunomodulatory gene expression and melanoma-T cell responses were investigated. The effects of dedifferentiation on immunomodulatory gene expression were assessed by siRNA mediated knockdown of MITF expression in 624Mel cells followed by IFNγ stimulation. Transcriptomic and epigenetic effects were assessed via RNA-seq and ATAC-seq, respectively. IFNγ-induced PD-L1 expression following MITF knockdown was evaluated in 624Mel, SK-MEL-28, A357P, Malme-3M and B16 melanoma cells by qPCR and western blotting. Small molecular inhibitors against the JAK kinases, STAT3 and NFκB and siRNAs targeting STAT1 and IRF1 were used to investigate PD-L1 regulation in 624Mel cells. Public RNA-seq data from patient-derived melanoma cell lines were analyzed to validate the broader relevance of the results. Co-cultures were performed using TCR-redirected T cells and GFP expressing melanoma cell lines at varying differentiation states in live-cell imaging assays. Cytokine secretion in the co-cultures was quantified using a Luminex assay. The results showed that dedifferentiation predisposes melanoma cells to IFNγ signaling through rearrangements in chromatin accessibility, resulting in widespread expression of immunomodulatory genes. PD-L1 expression in dedifferentiated 624Mel cells was mediated via the canonical JAK-STAT1-IRF1 pathway and accompanied by a significant increase in IRF and STAT transcription factor motif accessibility. Co-cultures of TCRredirected T cells and melanoma cell lines suggest that differentiation state does not impair antigen processing and presentation. However, the rate of cytotoxic T cell responses was reduced by IFNγ pre-treatment of either highly differentiated or undifferentiated melanoma cell lines, and by induced dedifferentiation via MITF knockdown. T cell derived secretomes following culture with undifferentiated melanoma cells contained less TNFα, Granzyme B, CXL10, MIF and CCL5 than when cultured with differentiated cells, while containing more PD-L1, IL-8, CD25 and IL-6, suggesting decreased T cell activation. In conclusion, melanoma dedifferentiation may directly mediate immunosuppression.
Holographic Models of Emergent Spacetime
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Physical Sciences, 2026) Mohan, Vyshnav; Lárus Thorlacius; Faculty of Physical Sciences (UI); Raunvísindadeild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
Black holes are exceptional laboratories where the apparent incompatibility between gravity and quantum mechanics can be sharpened. In this thesis, quantum features of black holes are probed using the holographic principle, with tools from quantum information and algebraic quantum field theory. Operator algebras provide a natural framework for studying gravity as an emergent phenomenon, and we identify sufficient conditions for the emergence of gravitational dynamics. Going in the opposite direction, quantum gravity effects in an eternal black hole can be modelled by adding certain non-perturbative quantum corrections to its semiclassical operator algebra. This leads to an approximate type I von Neumann algebra whose dimension is equal to the exponential of the Bekenstein-Hawking entropy with logarithmic corrections. Non-perturbative corrections also lead to the late-time saturation of holographic complexity, defined as the volume of a codimension-one extremal surface passing through the black hole interior. A second law associated with this complexity is used to establish a black hole singularity theorem. Non-perturbative corrections may become important during gravitational collapse. Black shells, which have been proposed as an alternative endpoint of collapse in string theory, are studied from a thermodynamic perspective and shown to be thermodynamically favoured over black holes for a range of temperatures.
Quantum fluctuations of non-Lorentzian black holes
(University of Iceland, School of Engineering and Natural Sciences, Faculty of Physical Sciences, 2026-08-26) Harksen, Matthias; Watse Sybesma; Faculty of Physical Sciences (UI); Raunvísindadeild (HÍ); School of Engineering and Natural Sciences (UI); Verkfræði- og náttúruvísindasvið (HÍ)
Ritgerðin fjallar um þyngdarskammtafræði. Hún kannar djúpstæð tengsl sem eru til staðar milli þyngdarfræði eins og henni er lýst í almennu afstæðiskenningunni og hornrækinnar skammtasviðsfræði í einni lægri rúmvídd. Þessi samsvörun nefnist þyngdarfræðileg heilmyndun og hefur ýmsar birtingarmyndir, en ein sú einfaldasta felur í sér að þyngdarfræði í tvívíðu tímarúmi með fastan neikvæðan krappa sé jafngild hornrækinni skammtasviðskenningu sem býr á jaðri þess. Í ritgerðinni er síðan rannsakað hvernig þessi samsvörun og skyldar hugmyndir taka á sig nýja mynd þegar horfið er frá hefðbundnum afstæðilegum samhverfum yfir í óafstæðilegar samhverfur, svo sem Galíleó-, Carroll- og Lifshitz-samhverfur. Meginuppistaða ritgerðarinnar eru þrjár rannsóknagreinar sem fjalla um ólíka þætti óafstæðilegrar þyngdarfræði. Fyrsta greinin fjallar um Carroll-strengjafræði, þar sem athugað er hvernig lýsa megi strengjum í markgildi þar sem hraði ljóss stefnir á núll, sem er viðeigandi lýsing í grennd við sjóndeild svarthola og á jaðri tímarúmsins. Önnur greinin fjallar um skammtafræðilega leiðréttingarliði við varmafræði tvívíðs þinilsviðslíkans sem fæst með víddarlækkun á Lifshitz-svartholi. Þar er markmiðið að varpa ljósi á hvernig varmafræðilegir skammtaeiginleikar svarthola hegða sér þegar horfið er frá hefðbundnum afstæðilegum samhverfum. Þriðja greinin fjallar um óafstæðilegt Galíleó-de Sitter rúm. Þar er leitast við að skilja betur óafstæðilega Newton-Cartan rúmfræði og afleiðingar hennar fyrir heimsfræði þar sem afstæðilegar forsendur eru ekki lengur til staðar í sinni hefðbundnu mynd. Auk greinanna þriggja inniheldur meginmál ritgerðarinnar alþýðlegan inngang. Þar má finna hugleiðingar um það hvers vegna grunnrannsóknir eru mikilvægar fyrir mannkynið og jafnframt stutta kynningu fyrir hinn almenna lesanda á því fræðasviði í háorkueðlisfræði sem greinarnar leggja sitt af mörkum til. Þar að auki fylgir fræðilegur kafli sem byggður er á röð fyrirlestra sem ég sótti í doktorsnáminu mínu. Sá kafli skýrir hið afstæðilega sjónarmið sem greinarnar sjálfar byggja á.

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