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Senast publicerade

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    Antibacterial Activity of Delafloxacin and Polymyxin B Against Planktonic and Biofilm-Associated Bacteria
    (2026) Priya, Ankita
    Abstract Biofilm-associated infections are difficult to treat because bacteria growing in biofilms show increased tolerance to antibiotics compared with planktonic cells. In chronic wound infections, Staphylococcus aureus and Pseudomonas aeruginosa are com monly detected and can contribute to persistent infection. This thesis investigated the antibacterial activity of delafloxacin and polymyxin B against S. aureus and P. aeruginosa under planktonic and biofilm-associated conditions. The antibiotics were tested alone and in combination for MIC determination, time-kill assays, biofilm treatment assays, and scanning electron microscopy. The results showed that both antibiotics reduced bacterial viability, with stronger effects generally observed at higher concentrations. Planktonic cells were more affected than biofilm-associated cells, supporting the increased tolerance of bacteria growing in biofilms. Combina tion treatment reduced bacterial survival in several conditions and showed stronger effects than single-antibiotic treatments. SEM analysis showed dense bacterial at tachment in untreated biofilms, while treated S. aureus and P. aeruginosa biofilms showed reduced bacterial coverage and altered biofilm structure. Overall, the find ings suggest that delafloxacin and polymyxin B have antibacterial effects against both planktonic and biofilm-associated bacteria, but complete biofilm eradication was not achieved under the tested conditions.
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    MRI Compatible Retention System for a Bone Conduction Device: An evaluation of required design changes to Sentio Ti™ Implant for compliance with 3 T MRI scans
    (2026) Alexandersson, Matilda; Luttu, Ebba
    Magnetic resonance imaging (MRI) compatibility is an important requirement for implantable hearing devices, as increasing numbers of patients are expected to undergo MRI examinations during their lifetime. This study evaluates the mechanical response of the Sentio Ti™ transcutaneous bone conduction implant under magnetic torque corresponding to a 3 T MRI environment, with the aim of assessing whether the current design meets established performance criteria defined at 1.5 T. A computational approach was conducted using an existing, experimentally validated finite element model developed in LS-DYNA. The model was used to simulate implant displacement and contact pressure on surrounding soft tissue under worst-case magnetic torque conditions. The torque at 3 T was estimated based on proportional scaling from 1.5 T. Parametric studies were conducted to investigate the influence of reinforcement wire properties and silicone stiffness on implant behaviour. In addition, alternative retention magnet concepts were explored through a concept generation process. The results show that increasing the magnetic field strength from 1.5 T to 3 T leads to a significant increase in mechanical response, with displacement rising from 3.12 mm to 5.65 mm and average contact pressure increasing by a factor of approximately 2–3. Among the investigated parameters, reinforcement wire diameter was found to have the greatest influence on reducing both displacement and contact pressure. However, achieving equivalent performance to 1.5 T through structural modifications alone requires design changes that may be impractical within current geometric constraints. Combined modifications of wire diameter and silicone stiffness provided more feasible solutions, although they did not fully replicate baseline pressure levels. The findings indicate that while structural optimization can significantly improve performance, it may not be sufficient to ensure MRI compatibility at 3 T without compromising design constraints. Modifications to the retention magnet system, such as enabling rotational alignment or controlled movement, are therefore identified as promising strategies. This work provides quantitative insight into implant behaviour at higher magnetic field strengths and supports the development of next-generation MRI-compatible bone conduction devices.
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    Evaluating Motion Model Hypotheses for Automotive Radar Tracking
    (2026) Andersson, Noel; Lundberg, Hannes
    Automotive radar is a core ADAS sensor due to weather robustness and direct Doppler velocity measurements, but radar multi-object tracking is challenged by heterogeneous and maneuvering target dynamics. This thesis evaluates a white-noise jerk model (CCA) and a curvilinear motion model (CTCA), each implemented in an EKF, and assesses whether combining them in an Interacting Multiple Model (IMM) filter improves robustness across scenarios. To enable an unbiased comparison between CCA, CTCA, and IMM, process-noise parameters and IMM transition/interactions are tuned automatically by formulating tracking as a black-box optimization problem. Performance is optimized using the probabilistic GOSPA (P-GOSPA) metric, which penalizes localization error as well as missed and false tracks under multi-Bernoulli set representations. CMA-ES is used to search the nonconvex parameter space without gradients. Evaluation is performed in a controlled MATLAB simulation with a four-corner radar configuration and known ground truth, fusing radar range-rate detections with object-level pseudo-measurements of position and orientation. Results show strong scenario dependence for single-model tracking and indicate that automated tuning is necessary to avoid biased motion-model conclusions, the IMM provides more consistent performance across diverse driving scenarios than either single model.
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    Transport Optimisation and Climate Impact of Mass Handling: Case Study of the Solhöjden Project
    (2026) Bromander, Alexander; Bäckman, Ida
    Within the construction sector, the transport and handling of excavated materials are major contributors to both project costs and climate impact. In the European Union, excavated rock and soil accounted for approximately 20% of total waste generation in 2020, highlighting a significant potential for improved resource management. Transportation over long distances and competition between receiving facilities is a key driver of both costs and CO2e emissions. Reducing transport distances through alternative routes to receiving facilities, increasing reuse of excavated materials, and using electric lorries for transportation could significantly reduce climate impact. The aim of this study is to evaluate how design changes in the Solhöjden residential project in Kungälv, developed by JM, affected excavated mass quantities, transport demand, climate impact, and cost savings per apartment resulting from reduced excavation volumes. To achieve this aim, three different project design versions were compared. Project version 1 (PV1) represents the original design prior to redesign, PV2 includes a raised basement floor level, and PV3 involves a reduced basement. The analysis was based on Life Cycle Assessment (LCA) in OpenLCA, combined with GIS-based modelling of transport routes to receiving facilities. The input data was primarily provided by JM and included delivery notes specifying transported weights, material types, vehicle types, and receiving locations. The study used a case study approach supported by interviews to obtain project specific information that could not be derived solely from the literature. The results show that design changes, including basement layout modifications, reduced excavation volumes and enabled construction of the project. Between PV1 and PV3, the total quantity of excavated masses decreased by approximately 28%, demonstrating substantial mass savings due to design changes. Costs related to excavation, tipping, and transportation were reduced by approximately 13,000 SEK between PV1 and PV3-RO (route optimised). Furthermore, replacing conventional lorries with electric lorries resulted in an approximate 17% reduction in total emissions, with near-zero direct emissions during operation. The study also identified that permitting processes, differences in municipal regulations, and a limited availability of receiving facilities often contribute to longer transport distances and create additional challenges in the management of excavated materials.