Publikationer från Uppsala Universitet
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Modelling lined rock caverns subject to hydrogen embrittlement and cyclic pressurisation in fractured rock masses
No full textThe technology of lined rock cavern (LRC) with great geographical flexibility is a promising, cost-effective solution to underground hydrogen storage. However, the air-tight steel tanks used in this technology are susceptible to material degradation due to hydrogen embrittlement (HE), potentially leading to leakage and structural failure, especial for LRCs constructed in complex geological conditions. In this paper, we develop a 2D multiscale numerical model based on the finite element method to assess the impact of HE on the LRC performance in fractured rock masses under cyclic gas pressurisation. Within this framework, a large-scale model is used to simulate the deformation and damage evolution of both fractured rock and an LRC under in-situ stresses and internal gas pressurisation, while a small-scale model captures HE in the steel lining of the LRC. Our simulations reveal that damage in the rock, concrete, and steel degradation is strongly affected by pre-existing fractures and in-situ stresses. Our results also reveal the presence of a strong positive feedback between hydrogen concentration and stress redistribution in the steel lining. Moreover, a comparison between models with and without considering HE illuminates that hydrogen concentration significantly contributes to steel degradation, particularly during the long-term LRC operation, highlighting the critical role of HE in the safety and performance of the LRC. The findings and insights obtained from our work have important implications for the design optimisation and performance assessment of LRCs for sustainable underground hydrogen storage
Renhållningen av stadsmiljön i det gamla Brygge och Stockholm, med några reflektioner över miljörättens historia
No full textContrasting Seasonal Variation of Photosynthesis in Evergreen and Deciduous Tree Species From a Tropical Forest
No full textMicroclimate differences in water availability can drive seasonal water use and photosynthetic variation among co-occurring tropical tree species, especially in forests with strongly seasonal climates. We studied a tropical forest site in the Western Ghats, India, and characterised seasonal differences in photosynthetic CO2 assimilation rates (Anet) among nine tree species with contrasting leaf habit and topographic affinities: deciduous species in dry hilltops, dry-affinity evergreens on slopes and wet-affinity evergreens in valleys. Surface soil moisture was lowest in hilltops, intermediate on slopes and highest in valleys, with higher levels during the wet period compared to the dry period. As expected, deciduous species on dry hilltops showed higher photosynthetic rates at the thermal optimum (Topt) during the wet period, while evergreen species showed no overall seasonal differences. Interestingly, evergreen species with a dry affinity on hill slopes showed higher Anet at the thermal optimum during the dry period compared to the wet period, despite lower soil moisture. This suggests that these species either have sufficient water availability during the dry period or possess a warmer thermal niche preference/adaptation. Across species, stomatal conductance (gs) at Topt was generally higher during the wet period, except for one evergreen species. Our findings illustrate seasonal differences in photosynthesis among tropical tree species across different leaf habits and topographic affinities
Multilingual performance of a multimodal artificial intelligence system on multisubject physics concept inventories
No full textWe investigate the multilingual and multimodal performance of a large language model-based artificial intelligence (AI) system, GPT-4o, using a diverse set of physics concept inventories spanning multiple languages and subject categories. The inventories, sourced from the PhysPort website, cover classical physics topics such as mechanics, electromagnetism, optics, and thermodynamics, as well as relativity, quantum mechanics, astronomy, mathematics, and laboratory skills. Unlike previous text-only studies, we uploaded the inventories as images to reflect what a student would see on paper, thereby assessing the system's multimodal functionality. Our results indicate variation in performance across subjects, with laboratory skills standing out as the weakest. We also observe differences across languages, with English and European languages showing the strongest performance. Notably, the relative difficulty of an inventory item is largely independent of the language of the test. When comparing AI results to existing literature on student performance, we find that the AI system outperforms average postinstruction undergraduate students in all subject categories except laboratory skills. Furthermore, the AI performs worse on items requiring visual interpretation of images than on those that are purely text-based. While our exploratory findings show GPT-4o's potential usefulness in physics education, they highlight the critical need for instructors to foster students' ability to critically evaluate AI outputs, adapt curricula thoughtfully in response to AI advancements, and address equity concerns associated with AI integration
The Savior from Within? : A study examining the relationship between internal remittances and school attendance in Nigeria
No full textThe purpose of this paper is to investigate the relationship between internal remittances and school attendance in Nigeria. As remittance flows have become increasingly important in both the global and the domestic economy, it has gained more acknowledgement within the field of research over the last decades. The theoretical expectation is that receiving remittances should relax liquidity constraints, leading to increased school attendance. A Linear Probability Model is used to investigate this potential relationship. Important findings point towards a positive relationship between internal remittances and school attendance. When controlling for state-fixed effects this correlation is not statistically significant, indicating that internal remittances might be correlated with state-specific factors. Further findings indicate that male children and children living in households with lower pre-remittance wealth see a higher correlation between internal remittances and school attendance
Political Dominance and Local Investment : An Empirical Study of Long-Term Public Investments in Swedish Municipalities
No full textThis study examines whether political dominance in Swedish municipalities affects long-term public investments. The results show a small negative effect, but estimates are generally not statistically significant. When dominance is broken down by party bloc, right-leaning dominance is linked to lower investment, especially in fixed assets, though this could reflect different levels of privatisation rather than a clear political effect. No strong link between political dominance and increased pre-election spending are found, as the findings are inconsistent and vary between the outcome variables. The explanatory power is low, and signs of autocorrelation suggest possible model misspecification. Overall, there is no strong evidence that political dominance leads to systematic differences in investment behaviour. Future research could look at contexts with more pronounced budget cycles or focus on how the magnitude of cyclical political behaviour influences long-term investment
When technology meets people : A qualitative study on AI implementation in Swedish healthcare
No full textDespite the rapid advances in artificial intelligence (AI), its integration into healthcare practice remains limited. This study uses a socio-technical perspective to investigate factors that enable or hinder the implementation of AI in healthcare organisations. By exploring key prerequisites and challenges, the study aims to provide insight into how sustainable and meaningful implementation can be achieved in practice, particularly through the interplay between technical systems and human experience. The study applies the Consolidated Framework for Implementation Research (CFIR) alongside complementary theories to analyse how AI is interpreted and integrated into clinical work. A theoretical model was developed to capture implementation dynamics from technical and individual perspectives. Empirical data were collected through sixteen semi-structured interviews with stakeholders across four professional domains (healthcare personnel, developers, strategists, and researchers). The findings highlight that successful implementation depends not only on technology, but also on the alignment of AI with local values and practices. User involvement, clear responsibilities and interprofessional communication were identified as critical enablers. Informal change agents also played a central role in translating innovation into meaningful use. The study deepens our understanding of how innovations are either embraced or resisted in complex systems by gathering experiences of the implementation of AI in the Swedish healthcare system
Experimental Insights into Horizontal Transfer of Fungal Starship Megatransposons
No full textStarships are a recently discovered class of cargo-carrying fungal megatransposons, whose phylogenetic distribution suggests that they are capable of horizontal transfer between species. In this project, I attempted to experimentally verify horizontal Starship transfer in a laboratory setting. I designed plasmid vectors to induce auxotrophy and insert a hygromycin resistance tag in the Starship of an Aspergillus fumigatus donor strain. I then confronted it with potential acceptor strains under different culturing conditions, intending to trigger horizontal transfer of the Starship element. I also used mycoparasitic Trichoderma as an acceptor strain, to investigate whether the close hyphal contact of mycoparasitic interaction would facilitate horizontal transfer. None of these experiments led to a detectable transfer event, emphasizing that the complexities of Starship transfer are not yet fully understood, and more work is needed to develop a working system for inducing it in laboratory conditions. Additionally, I bioinformatically identified three new putative Starships in Trichoderma virens, forming the first instance of Starships discovery in this genus.
Reuse of building materials in Uppsala County : A case study on the Academic hospital
No full textSyftet med denna studie är att undersöka nuläget och möjligheter för återbruk av byggnadsmaterial i Uppsala län. Att återbruka material är ett växande intresse men är fortfarande ovanligt. Återbruksmarknaden är underutvecklad och plattformar som används har en del hinder exempelvis saknas data för uppföljning. Studien undersöker även hur återbruk kan bli ekonomiskt försvarbart med tanke på de krav och förväntningar som ställs på exempelvis standarder och garantier. Tidigare information samt varierande teorier används för att argumentera för tre valda frågeställningar, nämligen hur ser återbruket ut i Uppsala län, vilka byggnadsdelar är lämpliga att återbruka samt vilka är de viktigaste utmaningarna som behöver lösas för att mer återbruk ska kunna ske i Uppsala län. Undersökningen utfördes metodiskt genom att samla in data från litteraturstudie, intervjuer av olika respondenter inom Uppsalaområdet men även genom en fallstudie på Akademiska sjukhuset i Uppsala. För fallstudien utfördes mätningar av olika byggmaterial som verkade lämpliga att återbruka. Sedan gjordes en jämförelse av priset för begagnat med priset för nytt. Slutsatsen var att många produkter gick att återbruka även om vissa hade mindre problem. Några av dessa produkterna är nämligen undertaksplattor, fönsterbänkar, toalettstolar, handfat och fönster. Slutligen föreslår studien lösningar till olika branschrelaterade problemen gällande återbruk. Dessa lösningar handlar om plattformar, byggregler, garantier samt informationsspridning. The aim of this study is to examine the current situation and the possibility for reuse of building materials in Uppsala County. Although there has been an increased interest in the reuse of material, it remains relatively uncommon. The reuse market is underdeveloped and the platforms that are used have some issues, for example when it comes to the data for follow-up. This thesis explores how reusing of materials can be financially justifiable despite standards and guarantee requirements. Existing information as well as varying theories are used to answer three selected questions, namely what the state of reuse looks like in Uppsala county, which building components are suitable for reuse and which are the most important challenges that need to be solved in order to enable more reuse in that region. Furthermore, this thesis was conducted by collecting data from a literature review, interviews and through a case study of the Academic hospital in Uppsala. For the case study, measurements were taken of different building materials that were deemed suitable for reuse. Then a comparison was made between the used price with the new price. The conclusion was that many products could be reused even though some had minor problems. Among those products that can be reused include ceiling tiles, window sills, toilet seats, sinks and windows. In conclusion, the study offers solutions to various industry-related problems regarding reuse. These solutions deal with platform deficiencies, building regulations, guarantees and information dissemination.
"Det kvittar, vad som än händer i världen kan ingen ta min utbildning ifrån mig" : Betydelsen och värdet av utbildning enligt unga vuxnas uppfattning
No full textFöljande studie undersökte huruvida unga vuxna i åldern mellan 20–30 år såg att utbildningsvalen de gjorde under sin skolgång och studietid varit värdefulla och/eller betydelsefulla. Studien intresserade sig därmed för hur unga vuxnas olika utbildningsbakgrunder påverkat sättet de ser på utbildning. Vidare ämnade studien också att undersöka hur hemmet bidragit eller format de unga vuxnas sätt att ta sig an studier. Utifrån fem kvalitativa semistrukturerade intervjuer med unga vuxna med olika utbildningsbakgrunder samlades det empiriska materialet in. Materialet analyserades genom att tematiseras utifrån fyra olika teman som sedan återkom genomgående i studien. Studiens främsta teoretiska utgångspunkt utgick från Pierre Bourdieu samt Jean-Claude Passerons tankegods. I studien är återkommande teoretiska begrepp nedärvt och förvärvat utbildningskapital, habitus, sociala rum och kapitalinnehav. Resultatet visade att studiens deltagare både tillägnade sina utbildningsval ett särskilt värde samt såg att de varit betydelsefulla. Värde sågs genom att den egna valfriheten togs hänsyn till och att den enskilde individens val respekterades. Värde menade studiens deltagare också återfanns i examensbevis samt genomförd högre utbildning. Betydelsefulla har studierna och utbildningsvalen varit gällande den personliga utvecklingen som studiens deltagare vittnade om. Utbildningsvalen visade sig även varit betydelsefulla gällande utökat utbildningskapital samt att studierna banat väg för olika nya möjligheter. Slutligen visade studien att nedärvt utbildningskapital kunde ge vissa fördelar gällande sättet det sågs på utbildning samt hur det navigerades kring utbildningsval. Men samtidigt visade studiens resultat att ett eget förvärvat utbildningskapital kunde vara lika gångbart då visioner, målbilder och framtidsdrömmar var det som förde de unga vuxna framåt