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Results from a Swedish model-based analysis of the cost-effectiveness of AI-assisted digital mammography
No full textObjectiveTo evaluate the cost-effectiveness of AI-assisted digital mammography (AI-DM) compared to conventional biennial breast cancer digital mammography screening (cDM) with double reading of screening mammograms, and to investigate the change in cost-effectiveness based on four different sub-strategies of AI-DM.Materials and methodsA decision-analytic state-transition Markov model was used to analyse the decision of whether to use cDM or AI-DM in breast cancer screening. In this Markov model, one-year cycles were used, and the analysis was performed from a healthcare perspective with a lifetime horizon. In the model, we analysed 1000 hypothetical individuals attending mammography screenings assessed with AI-DM compared with 1000 hypothetical individuals assessed with cDM.ResultsThe total costs, including both screening-related costs and breast cancer-related costs, were &lt;euro&gt;3,468,967 and &lt;euro&gt;3,528,288 for AI-DM and cDM, respectively. AI-DM resulted in a cost saving of &lt;euro&gt;59,320 compared to cDM. Per 1000 individuals, AI-DM gained 10.8 quality-adjusted life years (QALYs) compared to cDM. Gained QALYs at a lower cost means that the AI-DM screening strategy was dominant compared to cDM. Break-even occurred at the second screening at age 42 years.ConclusionThis analysis showed that AI-assisted mammography for biennial breast cancer screening in a Swedish population of women aged 40-74 years is a cost-saving strategy compared to a conventional strategy using double human screen reading. Further clinical studies are needed, as scenario analyses showed that other strategies, more dependent on AI, are also cost-saving.Key PointsQuestionTo evaluate the cost-effectiveness of AI-DM in comparison to conventional biennial breast cDM screening.FindingsAI-DM is cost-effective, and the break-even point occurred at the second screening at age 42 years.Clinical relevanceThe implementation of AI is clearly cost-effective as it reduces the total cost for the healthcare system and simultaneously results in a gain in QALYs.Key PointsQuestionTo evaluate the cost-effectiveness of AI-DM in comparison to conventional biennial breast cDM screening.FindingsAI-DM is cost-effective, and the break-even point occurred at the second screening at age 42 years.Clinical relevanceThe implementation of AI is clearly cost-effective as it reduces the total cost for the healthcare system and simultaneously results in a gain in QALYs.Key PointsQuestionTo evaluate the cost-effectiveness of AI-DM in comparison to conventional biennial breast cDM screening.FindingsAI-DM is cost-effective, and the break-even point occurred at the second screening at age 42 years.Clinical relevanceThe implementation of AI is clearly cost-effective as it reduces the total cost for the healthcare system and simultaneously results in a gain in QALYs.Funding Agencies|Region Ostergotland and Linkoping University; Linkoping University</p
Propagation of Opinions on Signed Graphs : Stability and Collective Wisdom
No full textThis thesis investigates how collective opinions evolve in social networks, focusing on two crucial, real-world factors: individual stubbornness and antagonistic inter-actions. Classical models of opinion dynamics typically assume a cooperative environment, where all individuals collaborate to reach an agreement, causing opinions to naturally draw closer to each other. However, many real-world scenarios—from political debates to online discussions—are defined by stubbornness, where individuals resist changing their stance, and by rivalry or distrust, which can actively push opinions apart. We address these phenomena through the framework of signed networks, which explicitly encodes antagonistic relationships. Unlike models that rely on structural balance—a clean division into two opposing camps—we adopt a repelling interaction mechanism, treating negative ties as additive repulsive forces. This approach offers a more flexible and realistic representation of complex, unbalanced social structures. The first contribution is a thorough analysis of the signed Friedkin–Johnsen (SFJ) model, which combines stubborn attachment to initial opinions with antagonistic interactions. This combination fundamentally changes system behavior: while the classical FJ model is always stable, the SFJ model can diverge. Therefore, we establish sufficient stability conditions and show that even when the model is stable, antagonism allows opinions to escape the the convex hull of the initial opinions, meaning that agents can adopt positions more extreme than anyone held at the start. The thesis then examines repeated discussions through a concatenated SFJ model, reflecting scenarios such as a series of negotiations. Here, stability in an individual discussion does not imply stability for the repeated process. Two distinct behaviors emerge when the individual discussion rounds are stable: opinions may temporarily move apart before reconverging to consensus inside the convex hull, or they may drift farther apart with each round, leading to divergence. The first case corresponds to a transient amplification, which is a known consequence of non-normal matrices and is often referred to as reactivity. Given these possibilities, we provide sufficient stability conditions for the concatenated SFJ model. This analysis is extended to explore the dynamics in more complex scenarios, including time-varying interaction structures and bipartite (two-camp) networks. Next, we address multidimensional opinion dynamics models, where agents debate several interdependent topics (for example, climate policy is inherently linked to economic policy). We show that a set of topics that would be stable if discussed independently can become unstable and diverge when discussed together. The analysis of repeated (concatenated) multidimensional interactions reveal diverse outcomes, from full or partial or bipartite consensus to divergence. Finally, we shift the focus from opinion convergence to the quality of resulting collective judgement and study the wisdom of crowds problem, i.e., analyze the conditions under which a group’s aggregated opinion becomes more accurate due to collective interactions. The improvement of wisdom depends entirely on the allocation of the social power vector—the centrality measure that each individual has in the group. In classical cooperative systems, the social power vector is positive, which confines the concentration region (the set of allocations that improve wisdom) to a simplex. In contrast, signed networks allow for negative social powers, which expands the concentration region beyond the simplex, to a hyperplane. The analysis on signed networks also leads to a critical insight: agreement does not imply accuracy. The group can become confidently wrong—converging with high certainty to a false truth. We also analyze the case where the agents’ initial opinions are correlated, and characterize the new concentration regions and their properties under these conditions
Continuity of care vs standard counselling for fear of birth : a Swedish comparative study
No full textBackground/Aims Treatment for fear of birth during pregnancy demonstrates inconsistent results. Continuity models of care show promise in this area. The aim of this study was to evaluate satisfaction with treatment for fear of birth in a midwifery continuity model compared to standard counselling in Sweden. Methods A total of 175 purposively sampled women who received care using a continuity of care model between 2021 and 2023 and a historical cohort of 467 women in previous studies who received counselling completed questionnaires about their experiences. Differences between groups were calculated using odds ratios. Results Women with fear of birth who experienced the continuity model were more likely to be satisfied with counselling (adjusted odds ratio: 2.26; P=0.043) and report that their fear disappeared or decreased (adjusted odds ratio: 4.03; P=0.002). These women also rated medical (adjusted odds ratio: 2.06; P=0.034) and emotional (adjusted odds ratio: 2.45; P=0.007) aspects of intrapartum care higher than those who received standard counselling. Conclusions Women were more satisfied with care received in the continuity model compared to standard counselling. Implications for practice Women who fear birth may benefit from receiving care in midwifery continuity models during pregnancy and childbirth. Implementation of such models is encouraged
Carbon trapping at the solid–liquid interface in cemented carbides
No full textInter-diffusion between the hard ceramic and ductile metallic phases in composite materials such as cemented carbides governs their mechanical properties. Understanding atomic-scale diffusion at these interfaces is key to uncovering the mechanisms that dictate microstructure evolution, establishing a foundation for tailoring the properties of WC Co composites through precise interfacial control. The interface between tungsten carbide (WC) and liquid cobalt (Co) is investigated using molecular dynamics simulations. An integrated approach is presented for computing the solid–liquid interfacial free energy by combining computer vision aided interface detection with the Capillary fluctuation method. Significant inter-diffusion is observed, with atomic displacements primarily localized at the interface for W and C, while Co exhibits homogeneous behavior in the liquid phase. The formation of C C bonded structures at the interface is identified as a critical factor influencing diffusion, introducing localized structural rigidity that reduces atomic mobility. Additionally, premelting phenomena below bulk melting temperatures gives rise to a heterogeneous interfacial zone containing residual solid WC patches and molten W-Co alloy. The inter-diffusion coefficients for W, C, and Co compare well with prior computational and experimental studies, validating the methodology. These findings offer new insights into the atomic-scale mechanisms driving interface evolution and provide a foundation for tailoring the properties of WC Co composites through precise interfacial control.QC 20251215</p
Correlates of pregnant women’s active and passive mobility: A smartphone-based tracking study in Barcelona, Spain
No full textUnderstanding the factors that shape daily mobility during pregnancy is essential for inclusive transportation planning that promotes active travel for all. Using smartphone-based Global Positioning System data from 860 pregnant women in Barcelona, Spain, we evaluated the correlates of active and passive travel in early and late pregnancy. We identified 33 correlates from 48 candidate variables including personal characteristics, the residential physical environment, the social environment, and temporal factors. The most important correlate across pregnancy was non-European ethnic origin, being associated with 10–15 min less daily active travel. In early pregnancy, commuting distance was the most important correlate, being positively associated with passive travel, while the COVID-19 pandemic was associated with less passive travel. In late pregnancy, residential walkability and having a university degree were positively associated with active travel. The neighbourhood education level was associated with more active travel, particularly during weekends. We discuss key priorities for supporting active travel during pregnancy
Eco-Friendly Recovery and Alloying of Metals from Spent Lithium-ion Batteries
No full textWith growing environmental concerns and the critical need for sustainable resources, metal recovery from secondary sources has gained importance. Among the techniques applied for this purpose, pyrometallurgy, which involves high-temperature processing, is a widely used method. However, this method faces challenges when recovering elements from spent Li-Ion Batteries (LIBs). Black Mass (BM), the residue left after mechanical shredding and physical separation of spent LIBs, is rich in valuable elements such as Co, Ni, and Li. This study investigates the pyrometallurgical recycling of BM from various types of LIBs. Initially, the high-temperature behavior of BM was examined to identify the critical reduction temperatures. A temperature of 600 °C was identified as critical. This temperature ensures the complete transformation of the cathode material into its constituent metal oxides (MeOs). Additionally, thermodynamic modeling indicated that up to 600 °C Li is present as Li2O or Li2CO3, while at higher temperatures, it forms LiAlO2 by reacting with Al. A temperature of 800 °C was found to fully reduce Co and Ni oxides to their metallic forms. Furthermore, it was also observed that heating the BM up to 700 °C, regardless of the atmosphere's oxidizing properties, resulted in evaporation of less than 10 % of the F in the BM. After investigating the high-temperature behavior of BM, in-situ alloying was introduced as an approach for recovering Co and Ni as alloying elements. This was achieved by the addition of Fe2O3/CuO to the BM, and consequently, the production of Fe/Cu-based alloys. The effect of mechanical activation on BM reduction and in-situ alloying was also examined, revealing varying effects across different BMs. While ball milling showed no effect on some BM samples, it enhanced the reduction rate in others by decreasing particle size. The variation in BM susceptibility to ball milling may result from the technique employed in producing the BM or the rate-influencing factors in its reduction. In samples where the reduction rate improved, ball milling resulted in lower C consumption and, consequently, reduced CO2 emission. In the final phase of this study, slag was incorporated into the in-situ alloying system, and Li and F evaporation were tracked under various slag conditions. Basicity was found to be a significant parameter, with a linear positive effect on Li evaporation and a quadratic effect on F evaporation.
Membrane technologies for treatment of urban wastewater streams and resource recovery
No full textStormwater and blackwater are two urban wastewater streams with potential as valuable resources. The stormwater quality varies depending on catchment, actual rain pattern, pollutants sources, etc. Blackwater contains nutrients and energy that can be recovered. In addition, it contains organics, metals, micropollutants and microorganisms which might affect the efficiency of downstream processes. Efficient removal of contaminants from both stormwater and blackwater is essential for their reuse and recovery of resources, including water and nutrients. Membrane technology offers an advanced solution to improve the quality of stormwater and blackwater. While a number of studies have explored the application of membranes for stormwater treatment, the varying quality of stormwater raises questions about membranes’ efficiency in separating pollutants from different qualities of stormwater. More research is needed to understand the reusability of treated stormwater using membranes as well as the recovery of metals in the concentrate. The overall aim of this study is to improve the quality of stormwater and source-separated blackwater, which has a direct impact on the reusability of stormwater as water resource and of struvite as a biofertilizer. Nutrient recovery from blackwater after membrane treatment is a new concept requiring further attention. Membrane cleaning is essential for maintaining membrane efficiency. For stormwater, regular backwashing with different durations and chemical combinations were tested, and the fouling layer on the membrane was analyzed, using a scanning electron microscope. Backwash water was characterised. For blackwater, the membrane cleaning method used included backwashing combined with aeration, raising the question about its adequacy. The ultrafiltration membrane was able to separate total suspended solids, oil, particulate metals, total phosphorus, turbidity and microorganisms from stormwater and effectively reduced organic compounds. After hygenisation, ultrafiltratered stormwater has a significant potential for non-potable uses, and its quality approaches potable standards, based on Swedish Food Agency. The struvite produced from membrane treated digestate resulted in struvite with more uniform struvite crystals, free of organic substances and metals (As, Ca, Cr, Cu, Pb and Si) stepping towards reusing this struvite as biofertilizer. The optimal backwash duration after stormwater treatment, for these set of experiments was 45 s considering membrane productivity. Chemical cleaning with sodium hydroxide, and with or without sodium hypochlorite followed by hydrochloric acid were compared which indicated that addition of sodium hypochlorite did not improve the efficiency of chemical cleaning. Analyses of the backwash water showed a high metal concentration which might indicate the potential for metal recovery. Combinations of backwash and aeration was an efficient method to preserve membrane initial flux after digestate blackwater treatment.
Modelling Dynamic Flow Conditions for Fish Habitats in Regulated Rivers
No full textHydropower is an important renewable energy source providing flexible operating conditions that balances the increasing intermittent energy from wind- and solar power. Hydropower however, comes with other environmental challenges by altering the ecological conditions in the rivers by presenting flow conditions such as hydropeaking. To fulfill the Swedish Environmental Code and the demand from the European Water Framework directive to achieve good ecological status (GES) for all watercourses, measures to improve the ecology in the river for each hydropower plant must be presented. Investigating potential restoration measures might be both costly and time-consuming as they are often specific to the site and species involved. Hydraulic modelling of flow conditions connected with individual-based models (IBMs) to evaluate fish population growth, and behaviour, is one way to make these estimations more cost- and time-efficient. The aim of this thesis is to investigate how the results of hydraulic models can be used with IBM’s and how different assumptions in the modelling process could create deviations that could further propagate into the IBM’s. A 2D hydraulic model over a regulated river in northern Sweden is presented where the restoration focus is improving European grayling habitat. As a first step, paper A investigates how modelling parameters could influence the hydrodynamics in the river, and in turn impact the habitat estimations. The results shows that the Neumann boundary conditions are more sensitive to Manning roughness than fixed water level boundaries, especially near upstream and downstream enclosure areas. A fixed water level boundary with velocity measurements at the inlet and outlet can minimize boundary effects on roughness calibration. Careful selection of roughness distribution areas, particularly in high-velocity zones, is crucial as it impacts bed shear stress, and velocities, which can be used for estimating feasible habitat. A gradual roughness transition between calibration areas may improve model accuracy. In a second step, paper B compares a steady-state interpolation method with transient simulations since the IBM implements steady-state simulations of different constant flows to interpolate the depth and velocities across the river for different discharge hydrographs. The goal was to assess how the limitations of a steady-state approach impact different parameters in the IBM’s and how this could affect the long-term habitat. Steady-state and transient simulations were compared, focusing on WSE, spawning habitat and bed shear stress. Steady-state models failed to capture temporal dynamics caused by neglect of time displacement and damping by assuming uniform response times across the river. The bed shear stress was under-predicted by the steady-state interpolation which could lead to inaccurate estimations of suitable spawning grounds and also, the risk of redd scouring. Uncertainties in the depths and velocities over time from the hydraulic model could propagate further in the IBM’s causing the long-term evaluation of fish population to be inaccurate especially when the flow conditions are highly varying during the years where a transient model is preferred. Finally, paper C investigates how the dynamic flow conditions effect the bed shear stress. When no substrate data over the riverbed is available, the bed shear stress can serve as a substitute for identifying suitable spawning areas as input for the IBM. The paper presents the hydraulic conditions in the river during a period of 2 months between May and July to capture the spring flood together with some hydropeaking events during summer. The spawning grounds considering depths and velocities were presented with the maximum bed shear stress during the time period to identify and evaluate possible restoration areas. To evaluate the stability of different spawning gravels used for restoration, the Wilcock-Crowe bedload transport model was implemented in the model. The erosion and sedimentation of the added spawning gravel followed the maximum bed shear stress curves. The results can be used further to evaluate different restoration measures together with the fish population growth with IBM
Materialkaraktärisering och processmodellering av varmformning av ultrahöghållfast stål för chassikomponenter i tunga fordon
No full textThe European Commission has set a target to reduce greenhouse gas (GHG) emissions from road transport by 60\% compared to 1990 levels by 2050, as outlined in the Transport White Paper. In 2012, passenger cars accounted for about 60\% of GHG emissions from the road transport sector, a figure expected to decline to 45\% by 2030. Meanwhile, heavy-duty vehicles (HDVs), including trucks, buses, and coaches, contribute around 26\% of total CO emissions in the European Union, with trucks alone responsible for over 85\% of this share. To achieve the 2050 goal, the European Commission has identified key strategies, including improving vehicle efficiency, developing sustainable propulsion systems, and using advanced lightweight material solutions. A promising approach to reduce fuel consumption and increase payload capacity in HDVs is to reduce vehicle weight. One method is the integration of ultra-high strength steels (UHSS) into chassis structures, enabling thinner, lighter components. However, the limited ductility of UHSS in cold-forming requires exploring alternative forming techniques. Warm forming of thick-walled UHSS sheets presents a viable solution. This thesis focused on the mechanical characterisation of WARMLIGHT-980, a novel 7~mm thick UHSS grade (UTS 980~MPa), developed for warm forming in the 430–580\textdegree C range. The goal of the forming process is to produce lightweight components with high stiffness and fatigue resistance, specifically for HDVs. The elastoplastic and ductile failure properties of this UHSS grade were investigated at elevated temperatures to support numerical simulations of warm-forming processes. Failure strains under various stress triaxialities and specimen geometries were determined by digital image correlation. Due to the thickness of the material, conventional full-scale specimens were impractical; thus, scaled-down 1.2~mm specimens were tested and validated against full-thickness tensile tests. Inductive heating was used to reach target-forming temperatures, with thermal photography confirming uniform distribution. A modified Mohr-Coulomb ductile failure model, calibrated at 3D stress states, was used to predict crack formation during forming. The thermo-mechanical simulation model was validated through three-point bending tests by comparing force-displacement responses. Thickness distribution from simulations was also compared with demonstrator components. Findings indicate UHSS can be effectively warm-formed into complex components at elevated temperatures. The calibrated material model accurately describes material behaviour, with simulation results closely matching experimental force measurements. This research supports the development of lightweight, high-performance HDV structures through improved forming processes and material modelling
Reflecting on student reflections in physical education practice : moving beyond a theory-and-practice divide
No full textBackground Although the theory/practice dualism seems difficult to deal with in physical education (PE) practice, this paper posits that there are ways in which teachers can enable students to develop holistic competencies that encapsulate elements of both theoretical and practical knowledge. We therefore seek to rethink the relationship between theory and practice in PE practice and present ways in which PE teachers can connect these forms of knowledge with their students. We do so by looking at one of the historically most favoured means of bridging theory and practice: reflection. Purpose The purpose of this paper is to contribute with knowledge about student reflection in PE practice. First, we discuss the concept of reflection to clarify how student reflection might be understood in the embodied and situated context of PE practice. Then, we reconceptualise reflection in a way that might enable teachers to bridge the gap between theory and practice in new and hopefully fruitful ways with their students. Theory and methods We draw on various theoretical traditions on reflection to present a reconceptualisation of reflection that encapsulates the practical, situated and embodied nature of PE. Theoretical discussion We present the following four key ideas pertaining to reflection that together create a framework for conceptualising student reflection in the PE context: 1) Why reflection is important: a matter of intelligent practice; 2) Students must learn to reflect – in relation to what?; 3) What should students reflect on?; and 4) The how questions: creating conditions for reflections through indeterminate situations. Drawing on these four key ideas, we present an example of how our theoretical discussions can form the following three intertwined principles for a pedagogy of student reflection in PE practice for PE teachers moving beyond a theory-and-practice divide in PE: 1) a pedagogy of becoming through reflection; 2) a pedagogy of reflecting on the plurality of embodied and situated meaning; and 3) a reflective pedagogy of enquiry and discovery. Conclusion Throughout this paper, we argue that students need to learn to reflect, we suggested how reflection could be facilitated and we proposed that the why(s), what(s) and how(s) should be the objects of student reflection in PE. It is necessary to highlight that our suggestions for a pedagogy of student reflection are not complete nor definite but could serve as points of departure for future discussions of student reflection in PE.