Publikationer från Uppsala Universitet
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Search for Higgs boson decays into a pair of pseudoscalar particles in the γγτhadτhad final state using pp collisions at √s = 13 TeV with the ATLAS detector
No full textA search for exotic decays of the 125 GeV Higgs boson into a pair of new spin-0 particles, H → aa, where one decays into a photon pair and the other into a τ-lepton pair, is presented. Hadronic decays of the τ-leptons are considered and reconstructed using a dedicated tagger for collimated τ-lepton pairs. The search uses 140 fb−1 of proton-proton collision data at a centre-of-mass energy of √s = 13 TeV recorded between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider. The search is performed in the mass range of the a boson between 10 GeV and 60 GeV. No significant excess of events is observed above the Standard Model background expectation. Model-independent upper limits at 95% confidence level are set on the branching ratio of the Higgs boson to the γγττ final state, B(H → aa → γγττ), ranging from 0.2% to 2%, depending on the a-boson mass hypothesis.For complete list of authors see http://dx.doi.org/10.1007/JHEP03(2025)190</p
Sociodemographic factors influencing SARS-CoV-2 vaccination uptake in people with and without HIV : Insights from a Swedish Nationwide cohort
No full textBackground There is limited data regarding SARS-CoV-2 vaccine uptake in people with HIV (PWH) compared to people without HIV (PWoH). Methods Swedish nationwide study of individuals born 1930–2003, assessing SARS-CoV-2 vaccine uptake of 1–5 doses by HIV-status from first SARS-CoV-2 vaccination (2020-12-27) until 2023-02-23. PWH were categorized by prioritization: clinically vulnerable (CD4+ T-cells <50cells/μL, recent opportunistic disease, or CD4+ T-cells <200 in combination with detectable HIV-RNA > 200copies/mL), and not prioritized (non-vulnerable PWH). Relative risks (adjRR) for doses 1–5 were estimated using modified Poisson regression, adjusted for sociodemographics, SARS-CoV-2 infections, and comorbidities. Results 7233 non-vulnerable PWH, 435 clinically vulnerable PWH, and 8,168,340 PWoH were included. While unadjusted 3-dose uptake was lower in both PWH groups compared to PWoH, adjusted analysis showed higher uptake in non-vulnerable PWH (adjRR1.17, 95 % CI 1.15–1.19), with similar trends in clinically vulnerable. An interaction between country of birth and HIV-status was identified (p < 0.001). Migrants with HIV had higher 3-dose uptake vs. migrants without HIV, but were less likely vaccinated than Swedish-born with HIV. Among people ≥65 years old, PWH were less likely to receive 3 or more doses compared to PWoH ≥65 years (dose 5: adjRR 0.90, 95 % CI 0.85–0.96). Conclusions We found lower vaccination uptake in migrants, irrespective of HIV-status, consistent with previous studies. Most concerningly we identified a lower vaccine uptake among people with HIV who were 65 years or older. This nationwide study highlights the need for targeted vaccination strategies and interventions that address both HIV-status and demographic factors
Belöningssystem som styrmedel i offentlig sektor
No full textMyndigheter har begränsat handlingsutrymme för att använda monetära incitament men är samtidigt beroende av engagerade medarbetare för att leverera hög samhällsnytta. Undersökningen utforskar hur Skatteverket utformar och använder belöningssystem som styrmedel för motivation i en kontext där ekonomiska belöningar är strikt reglerade. Studien har en kvalitativ design och bygger på fem semistrukturerade intervjuer med HR-specialister och enhetschefer samt analys av interna styrdokument. Self Determination Theory, Public Service Motivation, lön som styrmedel och Total Reward Model används som teoretiska ramverk. Resultaten visar att Skatteverket främjar inre motivation genom ett tydligt samhällsuppdrag och belöningssystem som stödjer medarbetarnas behov av autonomi och tillhörighet, medan bekräftelse av kompetens tillgodoses mer sporadiskt. Myndigheten erbjuder en varierad uppsättning belöningar som bland annat stärker balans mellan arbete och fritid, social trygghet och arbetsengagemang. Däremot saknas tillräcklig kompensation samt systematik i återkoppling och erkännande för att motivera anställda i den omfattning som krävs enligt det teoretiska ramverket. Slutsatsen är att statliga myndigheter kan motivera sina anställda utan bonusar genom att tydliggöra gemensamma värderingar, skapa utvecklingsmöjligheter och använda ett helhetsinriktat belöningssystem. Studien bidrar med praktiska rekommendationer och föreslår vidare forskning som inkluderar medarbetarperspektiv och jämförelser mellan olika myndigheter.
Automated Decision-Making in Creditworthiness Assessments and the Right to Explanation : A Study of Articles 15(1)h and 22 of the GDPR, Article 18 of the Consumer Credit Directive and Article 86 of the AI Act
No full textThis thesis examines the European Union legal framework governing individuals’ rights to access and explanation in automated creditworthiness assessments. Such assessments, conducted increasingly through artificial intelligence and machine learning systems, determine access to essential financial services and may significantly affect individuals’ socio-economic opportunities. The analysis focuses on the interplay between Articles 15(1)h and 22 of the General Data Protection Regulation, Article 18 of the Consumer Credit Directive II, and Article 86 of the Artificial Intelligence Act. Using the EU legal dogmatic method, the study evaluates relevant legislative provisions, case law from the Court of Justice of the European Union (including C-634/21 SCHUFA and C-203/22 CK v. D&B), and regulatory guidance from the European Data Protection Board. The thesis also discusses the concept of access to fair credit as a fundamental right in light of the Artificial Intelligence Act. The findings confirm that EU law recognises a substantive right to explanation in the context of automated decision-making, yet the scope and practical enforceability of this right remain constrained by factors such as trade secret protections, technical opacity of AI systems, and fragmented decision-making chains. While SCHUFA closed a potential loophole by recognising credit scores as qualifying decisions under Article 22, national interpretations vary, creating uncertainty for both data subjects and credit rating agencies. The thesis argues that the current framework provides important transparency and accountability safeguards but is insufficient to ensure meaningful contestation of algorithmic credit decisions in all cases. It concludes with recommendations to clarify the legislative standards governing the right to explanation, to promote harmonised interpretation and enforcement across the EU, and to ensure that transparency obligations are balanced proportionately against the protection of intellectual property and trade secrets
Ab Initio Study of Two-Dimensional Metallic Magnets : From Analysis of Synthesized Compounds to High-Throughput Screening for Novel Candidates
No full textTwo-dimensional (2D) magnetic materials hold great promise for next-generation electronic and spintronic technologies due to their unique properties driven by quantum confinement and high surface-to-thickness ratios. This thesis presents a comprehensive theoretical and computational investigation of 2D metallic magnets, encompassing both experimentally realized compounds and predictions of novel materials through high-throughput (HTP) simulations. A major focus is placed on the FenGeTe2 family (n = 3–5), a recently synthesized class of van der Waals magnets. We uncover a √3 × √3 R30◦ superstructure that better aligns with experimental observations. In this structure, the outermost Fe sublattice undergoes a unique splitting behavior and is prone to spontaneous vacancy formation, significantly impacting the magnetic properties. Co doping is shown to preferentially substitute these Fe split sites, modifying magnetic anisotropy and enabling easy-plane magnetism. At higher doping levels, a coexistence of ferromagnetic and antiferromagnetic interlayer couplings emerges. By comparing Density Functional Theory (DFT), DFT with Hubbard U correction (DFT+U ), and DFT combined with Dynamical Mean Field Theory (DFT+DMFT), we demonstrate that static correlation treatments fail to reproduce experimental magnetic properties. Dynamical cor- relations included via DMFT yield more accurate exchange interactions and Curie temperatures. The exchange mechanism in Fe3GeTe2 is found to involve both direct and indirect pathways, with p-orbitals of Ge and Te mediating the latter. In the search for new 2D magnets, we propose Mn2Mg2X5 (X = S, Se) as a stable family of half-metallic ferromagnets, and studied exchange interactions and predicted magnetic transition temperatures. We also explore FeXZ2 (X = Nb, Ta; Z = S, Se, Te) and their Janus variants, identifying exotic features such as canted magnetic anisotropy and emergence of skyrmions in the absence of an applied magnetic field. Lastly, we develop a high-throughput framework and explored Fe3XY2 compounds, where X and Y are p-block elements. Out of 529 screened Fe3XY2 compounds, 31 were identified as stable. Several trends and correlations were observed among the stable candidates. The exchange interactions confirm a predominantly direct mechanism for first-neighbor coupling and an indirect, p-orbital-mediated mechanism for second-neighbor and longer-range interactions. Notably, Fe3SiTe2 exhibits enhanced perpendicular magnetic anisotropy, while halide-containing compounds surpass the magnetic transition temperatures of synthesized Fe3GeTe2 and Fe3GaTe2. Furthermore, compounds with non-centrosymmetric structural ground states, such as Fe3AsBr2, offer promising avenues for realizing skyrmion-hosting two-dimensional magnets. The large datasets generated here provide a foundation for future machine learning approaches aimed at accelerating the discovery and understanding of 2D magnetic materials.
Foraging Accuracy across Environmental Gradients : Implications for Coexistence and Evolutionary Diversification
No full textForagers competing for a shared resource face the risk of extinction through competitive exclusion, unless resources can be effectively partitioned among them. Explaining competitor coexistence has challenged theoreticians for decades, leading to many explanatory mechanisms that facilitate coexistence. Differences in environmental adaptation is one such mechanism by which foragers can alleviate the effects of resource competition. So-called niche partitioning has been implemented in many theoretical models, giving key insights into the ecological and evolutionary dynamics at play. However, these models often define niches as static curves of foraging efficiency across the environment, thereby overlooking the possibility of foraging to be adaptive. Other models assume that foragers adopt an ideal free distribution (IFD), where resource use is optimal, combining utilization ability and resource availability. The ideal free distribution---while being a highly influential concept---is based on the unrealistic assumptions of omniscience and cost-free movement. In this thesis, I approach the problem of foraging behavior using a switching function, allowing for foraging accuracy to be adjusted. Using the adaptive dynamics framework, the effect of suboptimal foraging is analyzed in the context of community composition, niche partitioning, and gradual evolution. The model outcomesare compared to those obtained by assuming the extreme cases of random foraging and optimal foraging (IFD). All analyses are performed for two types of niche systems: the commonly used distinct preference system, and the less-studied shared preference system, which remains largely ignored within adaptive dynamics, despite its empirical relevance. The model outcomes demonstrate a positive correlation between foraging accuracy and community richness. For shared preferences, non-random foraging behavior is shown to even be a prerequisite for adaptive diversification. These insights highlight the relevance of considering adaptive behavior when studying emergence of ecological communities, as well as providing an easy-to-implement approach for relaxing the assumption of ideal free distribution
Tuning intermediate binding enables selective electroreduction of carbon dioxide to carbon monoxide on a copper-indium catalyst
No full textElectrosynthesis of carbon monoxide (CO) from carbon dioxide (CO2) and water driven by renewable electricity represents a sustainable route to carbon upgrading, but the lack of cost-effective catalysts hinders its scaling-up. Here, we judiciously designed a bimetallic Cu-In catalyst via in situ electroreduction of In-coated CuO nanowires. This facilely-prepared Cu-In catalyst delivers an excellent performance towards CO production in a flow cell, with a faradaic efficiency of CO of up to 91% at a geometric current density of -69 mA cm-2. Different from previous studies suggesting that In-modified Cu strengthens the adsorption of *COOH and/or weakens the binding of *H, we discovered that In acts as the active site. The modification of In by Cu weakens the adsorption of *CO. This facilitates a faster desorption of *CO, thus inhibiting the C-C coupling process. As a result, the formation of multi-carbon products is suppressed. This conclusion was drawn through a rigorous analysis of the electrochemical reduction of CO, the electrochemical adsorption of *CO and in situ Raman spectroscopy. Finally, we wired our CuIn-based electrolyzer to an efficient triple-junction solar cell for the demonstration of solar-driven CO2 conversion and achieved a solar-to-chemical energy conversion efficiency of greater than 10% for CO
Verification of instrument iFlash 1800, a chemiluminescence immunoassay method, by analysing IA-2 and ZnT8 autoantibodies in patients with type 1 diabetes
No full textThe Swedish healthcare system strives for better and complete diagnoses with the intent of keeping people safe to the best of their abilities. To do so, it is vital to correctly diagnose with confidence. In this study, we verify the instrument iFlash 1800, a chemiluminescence (CLIA) -method, by comparing it to the pre-existing, validated and verified instrument Gemini, which uses enzyme-linked immunosorbent assay (ELISA) -method. The reasoning behind this is because of the promising benefits of what the CLIA-method can offer quicker analysis, lower limits of detection and with a similar performance to that of Gemini. The comparison is performed using analysis of two autoantibody markers in serum, Islet Antigen 2 antibody (IA2) and Zinc Transporter 8 (ZnT8), which can indicate a debut of type 1 diabetes years before it fully becomes symptomatic. The results of this study showed that iFlash 1800 has a sensitivity of 83% and 77%, for IA-2 antibodies and ZnT8 antibodies, respectively. Both analysis had an overall estimate of 87% concerning agreement and a specificity of 100%. One questionable aspect was the comparison of lab result concentrations between ELISA and CLIA which were plotted against each other. An R-squared value of 55% for IA-2 and 75% for ZnT8 shows little to no confident answer that iFlash 1800 can replace ELISA at this time. However if more tests were to be analyzed and perhaps the instrument itself needs to be systematically calibrated, there is great potential for the instrument and how it can prevent longer queues and delay of treatment in the Swedish healthcare system.
Exploring Human Neural Stem Cells as an In Vitro Model for Evaluating Developmental Neurotoxicity : From In Vitro Method Optimization to the Assessment of Potential Neurotoxicity of Pharmaceuticals During Pregnancy
No full textThe foetal brain undergoes a highly dynamic and regulated process of development during pregnancy, involving critical events such as neural tube formation, proliferation, migration, differentiation, synaptogenesis, and myelination. These processes begin early in gestation and continue throughout foetal development. Exposure to certain medications and chemical compounds during this sensitive window can interfere with normal neurodevelopment and may manifest as long-term neurological disorders. Given the lifelong impact of early brain injuries, assessing the developmental neurotoxicity (DNT) of pharmaceuticals and environmental chemicals is of importance. Several medications, such as certain antidepressants and cholesterol-lowering drugs, are associated with an increased risk of developmental effects based on both clinical observations and preclinical studies. Despite this, many of these compounds remain in use during pregnancies, highlighting the need for more reliable and human-relevant testing strategies. Traditional animal models, although informative, often fall short in predicting human-specific outcomes due to physiological differences. In addition, their use in testing the toxicology and effects on neurodevelopment raises significant ethical concerns that further limit their applicability. In contrast, human stem cell-derived in vitro models offer a promising alternative for DNT testing. These systems enable compound screening, thereby reducing the need for animal use. Importantly, using clinically relevant drug concentrations in such models enhances the translational value of findings, making them a powerful tool for improving safety assessment. This thesis focused on developing and applying a human embryonic stem cell (hESC)-derived neural model intended for DNT assessment. A feeder-free protocol was optimized to generate neural stem cells, which were differentiated into multiple neural subtypes. Transcriptomic profiling was then performed at various time points to monitor maturation over time. The analysis showed a progressive shift toward a neuron–astrocyte co-culture with a strong GABAergic signature, following expected neurodevelopmental trajectories and underscoring the model’s physiological relevance and robustness. The model was then used to evaluate the effects of selective serotonin reuptake inhibitors (SSRIs) and statins, two common drug classes that could be prescribed during pregnancy. Fluoxetine (FlX) and paroxetine (PAR) impaired neurite outgrowth independent of serotonin reuptake inhibitor transporter (SERT). Furthermore, atorvastatin (ATO) and rosuvastatin (ROSU) were found to disrupt neurite development and to cause mitochondrial alterations, particularly with ROSU, suggesting potential risks to affect early brain development at clinically relevant concentrations
Occurrence of Non-Stationarity at Earth's Quasi-Perpendicular Bow Shock
No full textCollisionless shocks can exhibit non-stationary behavior even under steady upstream conditions, forming a complex transition region. Ion phase-space holes, linked to shock self-reformation and surface ripples, are a signature of this non-stationarity. We statistically analyze their occurrence using 521 crossings of Earth's quasi-perpendicular bow shock. Phase-space holes appear in 65% of cases, though the actual rate may be higher as the holes may not be resolved during fast shock crossings. The occurrence rate peaks at 70% for shocks with Alfv & eacute;n Mach numbers . These findings suggest that Earth's quasi-perpendicular bow shock is predominantly non-stationary