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Fractional differential problems with numerical anti-reflective boundary conditions from a numerical linear algebra perspective : A computational study with an extensive numerical validation
No full textIn the current work, we propose numerical anti-reflective boundary conditions (BCs) in the context of nonlocal problems of fractional differential type: the numerical linear algebra goal is a O(N log N) complexity of the resulting direct and iterative algorithms, accompanied by a qualitative better approximation, with the mitigation of boundary artifacts. In fact, for showing the quality of the numerical anti-reflective BCs, we compare various types of numerical BCs, including the anti-symmetric ones considered in the case of fractional differential problems for modeling reasons. More in detail, given important similarities between anti-symmetric and anti-reflective BCs, we compare them from the perspective of computational efficiency, by considering non-truncated and truncated versions, and also other standard numerical BCs such as periodic BCs or reflective/Neumann BCs. A short theoretical analysis and several numerical tests, tables, and visualizations are provided and critically discussed. The conclusion is that the truncated numerical anti-reflective BCs perform better, both in terms of low computational cost and accuracy
Timing of MRI for early treatment response prediction of chemoradiotherapy in uterine cervical cancer
No full textAim: To explore the optimal use of MRI including time point to predict early treatment response during definitive chemoradiotherapy in cervical carcinoma. Methods: Pilot study including 15 patients with cervical carcinoma stage IIB-IIIB (FIGO 2009) scheduled for chemoradiotherapy. All patients underwent four MRI examinations (at baseline, 3 weeks, 5 weeks, and 12 weeks after treatment start). Maximum tumor size, size change (Delta size), visibility on diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) mean and change in ADC (Delta ADC) at the different time points were recorded. Results: 7/15 patients relapsed during the study period, referred to as "poor prognosis" (PP) and the remaining 8/15 are referred to as "good prognosis" (GP). At all four time points, the tumors in the PP patients were larger than in the GP patients. Tumor size did change between the time point but this was not significant between the groups. Visible tumor on high b-value DWI reached a sensitivity and specificity for predicting prognostic group being highest at 5 weeks, 83 % (5/6) and 63 % (5/ 8), respectively. The combination of tumor size at baseline and visible tumor on DWI at 5 weeks, resulted in an area under the curve (AUC) = 0.83. At 12 weeks, no GP patients, but 2/7 PP patients showed visible tumor on DWI. Addition of ADC-values in the analysis did not improve the predictive value at any time point. Conclusion: This pilot study indicates that the tumor size on baseline MRI, combined with tumor visibility on DWI at 5 weeks, may predict outcome of chemoradiotherapy
Radiation doses in ventriculoperitoneal shunt catheter imaging - Comparing traditional plain radiography with computed tomography and photon counting computed tomography.
No full textINTRODUCTION: Hydrocephalus is a common condition with enlarged ventricles in the brain. It is often surgically treated with a ventriculoperitoneal shunt system. These patients require regular radiological controls, which exposes them to a cumulative dose of ionizing radiation. The aim with this study was to identify CT protocols that provide diagnostically adequate image quality with equal or lower radiation dose, compared with traditional plain radiography. METHODS: Four anthropomorphic phantoms representing pediatric patients of ages 1, 5 and 10, and an adult, were imaged with a series of CT protocols on three different scanners (including one photon counting) to determine a protocol that would offer the lowest radiation dose with adequate image quality. The image quality was visually assessed and graded by two radiologists. For comparison, a retrospective study was conducted on patients who had undergone a shunt series with plain radiography from April 2021 to December 2023. RESULTS: The mean effective dose for all the 137 patients imaged with plain radiography was 2.35 mSv, ranging from 0.14 to 3.73 mSv. The mean effective dose increased with age. For all four phantoms, the study identified at least one CT protocol that provided a lower effective dose than the mean dose from plain radiography in the respective age group, as well as one minimal dose protocol per patient group. As expected, CT examinations had significantly shorter time durations (approximately 10 s vs 14.9 min for adults). CONCLUSION: This study showed that various low-dose CT protocols, with or without photon counting technology, can be used for imaging ventriculoperitoneal shunt catheters, with comparable or lower effective dose compared with plain radiography. IMPLICATIONS FOR PRACTICE: A transition from plain radiography to CT offers several benefits, such as decreased discomfort for the patient, shorter examination time, richer imaging data, and decreased radiation dose
AdAPT : Advertisement detector adaptation under newspaper domain shift with null-based pseudo-labeling
No full textDetecting advertisements in digitized newspapers is a key step in large-scale media analytics and digital archiving. However, variations in layout, typography, and advertisement design across publishers and time periods cause significant domain shifts that reduce the generalization ability of supervised detectors. This paper presents AdAPT, a confidence-guided pseudo-labeling pipeline for unsupervised domain adaptation in advertisement detection. The proposed method leverages both advertisement-free (Null) and advertisement-containing pages from unlabeled target domains to generate reliable pseudo-labels. By retraining a YOLO-based detector using labeled source data combined with filtered pseudo-labeled target samples, AdAPT achieves robust adaptation without requiring manual annotation. Experiments conducted on two unseen newspapers (Adresseavisen and iTromsø) demonstrate that Null-based pseudo-labeling provides the most stable and accurate adaptation, yielding up to 38% error reduction compared to the baseline. The results highlight AdAPT as a simple, scalable, and annotation-efficient solution for maintaining high-performance advertisement detection across diverse newspaper collections.CC BY 4.0Corresponding author: Faeze Zakaryapour SayyadReceived 16 October 2025, Revised 21 November 2025, Accepted 30 November 2025, Available online 1 December 2025, Version of Record 3 December 2025.Declaration of competing interestThe authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Faeze Zakaryapour Sayyad reports financial support was provided by Mid Sweden University. Faeze Zakaryapour Sayyad reports a relationship with Knowledge Foundation (kks.se) within the Industrial graduate school Smart Industry Sweden, Media Research company that includes: employment and funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.AcknowledgmentThis work was supported in part by The Knowledge Foundation(kks.se) within the Industrial graduate school Smart Industry Sweden and Media Research AB. The authors would also like to thank Oscar Berg for his valuable comments on this work.</p
Modeling and Simulating Cyberattacks with Dynamic Graphs : With applications to cloud security assessments
No full textThis dissertation presents a formalism for exploring two fundamental, yet underrepresented, cyberattack dynamics. Namely, how adversary actions drive the emergence of cyberattacks and how adversaries manipulate dynamic system structures, such as by creating and destroying objects. The formalism in question is encapsulated in the Dynamic Meta Attack Language (DynaMAL), a meta-level formalism for modeling and simulating cyberattacks with dynamic graphs. DynaMAL has been designed and developed in accordance with the design science research framework across four studies. The first study introduces an attack graph construction language for assessing cloud architectures and identifies the central problem of representing attacks in which adversaries manipulate dynamic system structures. The second study is a systematic literature review of cyberattack simulations that identifies key simulation concepts used in later stages of the design process. Building on the two initial studies, the third study establishes the cyberattack modeling foundations of DynaMAL, comprising a dynamic graph system, a multi-layered graph model, a lazy graph generation strategy, and the DynaMAL grammar. Finally, the fourth study develops the corresponding discrete-event simulation process for DynaMAL. The resulting capabilities are evaluated through a first simulation experiment that uses three cloud penetration testing scenarios that rely on dynamically creating and destroying resources. The scenarios are then solved automatically with near-optimal results by combining two search and optimization algorithms.I den här avhandlingen presenteras en formalism för att utforska två fundamentala men underrepresenterade cyberattackdynamiker. Dessa är hur antagonisters handlingar driver fram cyberattacker och hur antagonister manipulerar dynamiska systemstrukturer, till exempel genom att skapa och förstöra resurser. Formalismen i fråga är inkapslad i ett Dynamic Meta Attack Language (DynaMAL), en formalism på metanivå för att modellera och simulera cyberattacker med dynamiska grafer. DynaMAL:s design och utveckling fortlöper genom fyra studier utförda i enlighet med designforskningsramverket. Den första studien bidrar med ett attackgrafkonstruktionsspråk för att utvärdera molnarkitekturer, vilket utvecklar problematiken med att representera när antagonister manipulerar dynamiska systemstrukturer. Den andra studien är en systematisk litteraturstudie som granskar cyberattacksimuleringsforskning och uppdagar flertalet nyckelkoncept som understödjer de senare designaktiviterna. I den påföljande tredje studien etableras ett fundament för cyberattackmodellering innefattandes ett dynamiskt grafsystem, en lagerbaserad grafmodell, en lat grafgenereringsstrategi och DynaMAL-grammatiken. Den fjärde studien färdigställer DynaMAL-formalismen genom att implementera en motsvarande diskret händelsestyrd simuleringsprocess. De resulterande förmågorna utvärderas via ett första simuleringsexperiment, varvid tre molnpenetrationstestningsscenarion som krävde att resurser dynamiskt skapades eller förstördes används. Scenariona löses sedan automatiskt med nära inpå optimala resultat genom att kombinera två sök- och optimeringsalgoritmer.QC 20251219</p
Economic Evaluation of a Problem-Solving Intervention With Workplace Involvement Among Employees With Common Mental Disorder in Swedish Primary Care: Results From a Cluster-Randomized Controlled Trial
No full textObjectives The aim of this study was to evaluate the cost-effectiveness of a problem-solving intervention with workplace involvement (PSI-WPI) compared with care as usual (CAU) among employees on sick leave due to common mental disorders in Swedish primary healthcare centers. Methods Employees aged 18 to 59 years on sick leave for common mental disorders (n = 197) were included in a controlled cluster-randomized trial by coordinators (n = 19) recruited at primary care centers in Region Västra Götaland, Sweden. The study was conducted between February 2018 and August 2021, with 18 months of follow-up per participant. The economic evaluation included a cost-effectiveness analysis comparing changes in sick leave with direct costs from a healthcare perspective, calculated from register data, and intervention costs; a cost-utility analysis based on EQ-5D questionnaires and a societal perspective included indirect costs calculated from registered sick leave. Sensitivity analyses explored robustness to alternative missingness assumptions. Results The PSI-WPI resulted in more sickness absence (average 40 extra days; 95% confidence interval, 3-77 days) compared with CAU and higher healthcare costs (SEK 21 650, SEK 4962-48 262) over 18 months. At 12 months, the cost of care was SEK 23 734 (SEK 537-46 931) higher in the PSI-WPI group. The difference in quality-adjusted life-years between the groups was negligible. The sensitivity analysis indicated robust results, and diagnoses not targeted by the study were important cost drivers. Conclusions The PSI-WPI was not cost-effective for employees on sick leave due to common mental disorders compared with CAU only
Naturbaserade interventioner för att främja hälsa hos personer med stressrelaterad ohälsa
No full textStress-related illness is increasing and is a common cause of sick leave in Sweden. Spending time in nature reduces stress and promotes health and well-being. Consequently, nature-based interventions (NBI) for people with stress-related illness have been developed, implemented and studied in southern Scandinavia. However, such interventions are uncommon in the Circumpolar North with a different climate which affect conditions for outdoor activities. The overall aim of this doctoral thesis was to explore NBIs to promote health in people with stress-related illness from the perspectives of previous research, people with stress-related illness, healthcare professionals and entrepreneurs offering NBIs with a specific focus on northern natural conditions. The thesis includes four studies. An integrative literature review (I) identified and summarised scientific studies of NBIs for people with stress-related illness. Studies using both qualitative and quantitative designs were included. Study II explored key stakeholders’ perceptions of the value of NBIs in promoting health in people with stress-related illness. Semi-structured interviews were conducted with people with stress-related illness experience, healthcare professionals, and entrepreneurs offering NBI and data were analysed through qualitative content analysis. In study III people with stress-related illness experiences of participating in an NBI program in a northern natural setting were explored. A longitudinal case study design was used, and data were collected through repeated semi-structured interviews, diary entries and self-assessment questionnaires. Qualitative content analysis was used to analyse interviews and reflections from diaries and data from self-assessing questionnaires were presented descriptively. Study IV explored people with stress-related illness experiences of nature prescription. Data were collected through interviews with open-ended questions and analysed with a phenomenological-hermeneutic method. Findings show that natural environments offer unique qualities for individualised, meaningful activities and interactions with others in a non-demanding atmosphere. In NBI people with stress-related illness find a source for recovery, joy, and well-being. Spending time in nature is perceived as calming and facilitates being in the present. NBIs improve health and strengthen self-efficacy and work ability. Time in nature provides new perspectives, supports existential reflections, and empowers people with stress-related illness to find opportunities for change to achieve balance in everyday life. NBIs can be helpful for people with stress-related illness to overcome barriers to going out in nature or to find their way back to nature. In conclusion, NBIs seem to be beneficial in promoting health in people with stress-related illness. Different stakeholders have similar perceptions of the value of NBIs, indicating that it could be a valuable complement to health care. NBIs in a northern natural setting seems to have similar health promoting qualities as those seen in studies of NBIs in other natural settings
Ecohydraulic approach for ecological measures in regulated rivers
No full textHydropower is an energy source that is currently considered to be both climate- and environmentally friendly. It is utilized on both large and small scales and has a low carbon footprint, which has led to increased attention in recent years. The growing influence of renewable energy sources such as solar and wind power has also brought the regulatory capabilities of hydropower within electrical grids into focus. Despite the significant climate benefits of hydropower, there remain substantial challenges in adapting it to minimize environmental impacts. The latest European water framework has highlighted how fish and other aquatic organisms are harmed by limitations on upstream and downstream migration caused by hydropower plants. Given the importance of maximizing hydropower electricity production while minimizing environmental impacts, there is a need for more knowledge regarding how mitigation measures for aquatic organisms can be implemented. By combining knowledge of water flow patterns in hydropower areas with insights into the behavior of fish species in these environments, it is possible to facilitate migration both upstream and downstream while ensuring optimal use of hydropower. The first section focuses on downstream migrating salmon smolts. In this study, telemetry data from tagged smolts were analyzed alongside a 3D flow model of an area in northern Sweden where a large hydropower plant affects one of the largest rivers for salmon reproduction. The study shows that the smolts follow the main channel and are influenced by the flow rate. Higher flow velocities tend to cause the smolts to concentrate more in the main channel, while lower flows result in a broader distribution across the riverbed. The smolts are also partially influenced by the boom installed to direct the flow towards the fish pass. The second work section addresses how climate change may impact extreme flow events in a dammed river in northern Sweden. With anticipated climate change, more significant variation in precipitation is expected to affect the northern hemisphere, resulting in altered flow conditions. By studying historical data, an extreme flow event was identified and modeled using a 2D model. Flow variations were analyzed in relation to the preferred flow conditions for grayling. The study demonstrates that grayling are sensitive to large flow variations in the area. The most significant impact occurs when an extreme flow coincides with their spawning period. As the area is heavily regulated with hydropower plants placed closely together, downstream plants have a significant impact on water levels upstream. The area is particularly sensitive if water levels are rapidly lowered, as this can lead to stranding. This study combines various methods to investigate flow and flow variations, utilizing both detailed 3D models and broader 2D models. It demonstrates the potential for flow models to interact with ecological studies to deepen our understanding of the ecological state of rivers affected by hydropower development. This is a broad field with significant knowledge gaps, and it is hoped that further studies will be conducted in the future
Balancing grazing and biodiversity : arthropod responses to modern cattle farming practices
No full textRuminant production exerts severe pressure on ecosystems through land use change for pasture and fodder production, contributing to biodiversity loss, disruption of natural biogeochemical fluxes, and climate change. Whereas ruminant production can support biodiversity that has co-evolved with grasslands and grazing animals, the values of temporary grasslands are poorly understood. In this study, we assessed the effects of grazing regimes practised on modern cattle farms, including no grazing, on the abundance, biomass, and taxonomic richness of aerial and ground-dwelling arthropods. We assessed the potential value of organic management compared to grazing on conventional farms, and the role of vegetation structure on the pastures. We sampled arthropods in temporary pastures and silage grasslands, spring cereal fields, and in farmyards on 43 dairy and suckler cow farms in Finland. We show that grazing benefits the richness of ground-dwelling arthropods in fields, and the benefits were most evident at extensive levels of grazing at the farm scale. Grazing had no significant benefits for the biomass of ground-dwelling arthropods or relative abundance of aerial arthropods over field vegetation. Grazed rotational grasslands had similar levels of arthropods as mown grasslands or cereal crops, except for a higher richness of ground-dwelling arthropods. Taxonomic richness of ground-dwelling arthropods was higher on organic farms than conventional, but only at low grazing intensities. Although our study suggests several ways in which livestock farmers can maintain and increase arthropod populations on their farms, these may be associated with some reduction in production output on modern farms oriented towards high yields
Can Individuals with Visual Field Loss Drive Safely?
No full textIn Sweden, individuals with detected visual field loss (VFL) will have their driver’s license withdrawn based on perimetry results. In a previous study, a simulator-based method was used to test VFL individuals driving performance. Over 200 VFL individuals passed the simulator test and regained their driver’s licenses. Method: Seventy of the VFL individuals who had their driver’s license withdrawn due to VFL but then regained it after passing the simulator test and still had a valid driver’s license in February 2022 took part in a regular on-road driving test study. In addition, one age matched, and one younger control group (both groups matched on driving experience as well as area of living) also participated in this on-road study. Traffic inspectors, blind to group affiliation assessed the participants in cars provided by the exam office. Results: Just over 67% of the VFL participants passed the on-road test while almost 66% of the age- matched and just over 81% of the young controls passed the test. No statistical differences exist between the three groups. Discussion: The process used in Sweden for withdrawing driver’s licenses due to VFL seems to be unfair as all results indicate that participants with a detected VFL passed the on-road driving test to the same extent as did their matched controls. Second, a comparative study is needed to clarify if a simulator-based method or on-road testing is to prefer. Conclusion: Perimetry alone cannot predict driving performance on a driving test in a simulator nor on an on-road driving test assessed by traffic inspectors.