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Development of a quantitative job exposure matrix for standing, walking, and forward bending among pregnant workers - The PRECISE JEM
No full textObjectives Occupational physical activity (OPA) during pregnancy has been linked to adverse pregnancy outcomes, but crude exposure assessment remains an issue in causal inference. We aimed to develop a quantitative trimester-specific job exposure matrix (JEM) for standing, walking, and forward bending among pregnant workers. Methods Accelerometer measurements from 403 female workers across 109 DISCO-08 job codes were obtained in Denmark between January 2023 and June 2024. Full workdays were measured during two weeks among pregnant workers and one week among non-pregnant workers. We used linear mixed-effects models to estimate exposure levels of occupational standing, walking, and forward bending for all 1171 DISCO-08 codes, including age, trimester, and expert ratings as fixed effects, and job codes and workers as random effects. Results The between-job variances relative to total variances were 56% for standing, 51% for walking, and 45% for forward bending. The fixed effect trimester reduced standing time by 0.38 hours during the 3rd trimester compared to non-pregnant participants, whereas no differences were observed for walking or forward bending. Based on the trimester-specific JEM for occupational standing time, bakers had the highest exposure (range from non-pregnant to 3rd trimester, 5.41-5.03 hours/workday). For walking and forward bending, the highest exposed jobs from the pregnancy-specific JEM were waiters (1.76 hours/workday) and livestock/dairy producers (1.24 hours/workday), respectively. Conclusions The JEM enhances independent objective exposure assessment in epidemiological studies of OPA and pregnancy outcomes and may advance guidelines and potentially prevent adverse pregnancy outcomes
Familial risk of myocardial infarction with non-obstructive and obstructive coronary arteries : a nation-wide cohort study
No full textIt is unknown whether a familial risk of myocardial infarction is important for developing myocardial infarction without obstructive coronary arteries (MINOCA). In our study, we observed an increased familial occurrence for myocardial infarction with obstructive coronary artery disease (MI-CAD) when compared to control subjects whereas no increased familial occurrence of MINOCA was seen among MINOCA patients. These results may indicate that genetic factors and shared environmental factors within a family leading to CAD are important also for MINOCA, thus MI-CAD and MINOCA could share underlying mechanisms
Korrosion av Ni-baslegeringar - en studie kring degraderingen av spridarmaterial i BWR-miljö
No full textKärnkraften i Sverige står idag för ungefär 30% av Sveriges elproduktion och utgör en viktig fossilfri baskraftkälla som kan bistå med leveranssäker elproduktion under i princip alla väderförhållanden. Kärnkraftverket i Forsmark består av tre kokarvattenreaktorer (BWR) vid namn Forsmark 1, Forsmark 2 och Forsmark 3 (F1, F2 och F3) där F1 gick i kommersiell drift 1980, F2 1981 och F3 1985. F1 och F2 är näst intill identiska, av modellen BWR69, medan F3 är av modellen BWR75. Modern bränsleelementsdesign som ingår i Forsmarks reaktorer är utrustade med spridare som ger mekanisk stabilitet till bränsleknippen och optimerar reaktorvattenflödet för att undvika torrkokning. Spridarna är tillverkade av Ni-baslegeringar av typen Alloy X-750 (X-750) eller Alloy 718 (718). Under drift exponeras bränsleelementet för högtemperaturvatten och ånga som genomgår radiolys i reaktorn på grund av den intensiva strålningen. Detta skapar en kemiskt aggressiv miljö som påverkar alla konstruktionsmaterial i bränsleelementet. Att använda material som är anpassade till BWR-miljö är därför avgörande för att motstå korrosionsangrepp och upprätthålla bränsleelementets integritet. På Forsmarks reaktorer har på senare tid förhöjda mängder observerats av den radioaktiva isotopen 58Co och syftet med examensarbetet är att undersöka korrosionsbeteendet av olika BWR-spridarmaterial som kan bidra till ökad koncentration av den radioaktiva isotopen 58Co i reaktorvattnet. I arbetet beskrivs kunskapsläget kring korrosion av Ni-baslegeringar i BWR-miljö liksom kunskapsluckor baserade på erfarenheter från reaktorerna på Forsmark. I arbetet utvärderas också omfattningen av misstänkt spridarkorrosion och ifall spridarnas mekaniska integritet äventyras. Arbetet fokuserar på att ta fram vilka parametrar som påverkar korrosionsprocessen av Ni-baslegeringarna, relevant för Forsmarks vattenkemi. Resultatet förväntas ge utökad förståelse kring varifrån den förmodade korrosionen av Ni-basspridarna kommer, som i sin tur ger ökning av bland annat aktiveringsprodukten 58Co i reaktorvattnet. I arbetet analyseras vattenkemidata från Forsmarks reaktorer, tidigare inspektioner av bränslepatroner samt utförs materialanalys av spridare i tillverkningstillstånd med svepelektronmikroskopi (SEM) och energidispersiv röntgenspektroskopi (EDS). Genom att analysera vattenkemidata, insättning av bränslepatroner och bilder från tidigare bränsleelementsinspektioner visade det sig att isotopökningen skulle kunna härstamma från korrosion av spridare tillverkade av legeringen X-750. Isotopökningen i reaktorvattnet för Forsmark 1 och 2 sammanfaller med insättningen av en specifik bränsleelementdesign B1. Undersökningarna visar att korrosionsmekanismen som drabbar X-750-spridare i Forsmark 1 och 2 antas vara allmän korrosion, där viss indikation finns kring att flödet har en inverkan på korrosionen. Spridarnas strukturella integritet anses dock inte vara påverkad. Mikroskopiundersökningarna av spridarmaterial B1 i tillverkningstillstånd visar specifika trender i ytoxiden för Ti-, Ni- och Fe-halterna och en mikrostruktur med små korn och deformationer nära ytan. Tidigare undersökningar visar att ytoxidens sammansättning och mikrostruktur är kritisk för att ge den passiveringen som behövs för att skydda spridarna från korrosion. Ni- och Fe-halterna nära ytan är viktiga för uppbyggnad av ett skyddande NiFe2O4-skikt, vilket indikeras inte vara heltäckande för spridarmaterial B1 utifrån låga halter Ni och Fe i ytoxiden. Hos spridarmaterial i B1 observerades även hög Ti-halt i oxidskiktet vilket tidigare har visats bidra till ett sämre vidhäftande oxidskikt. Dessa fenomen kan utgöra den primära orsaken till den observerade tendensen till oxidflagning/oxidupplösning samt den ökade korrosionsbenägenheten hos B1-spridarna. Förslag på framtida undersökningar som identifierats är bland annat att utreda potentiella förändringar som kan ha inträffat i vattenkemin i F1 och F2 år 2021 och framåt, bedöma omfattningen av korrosion på spridarna genom en detaljerad analys av potentiella skillnader i föroxideringsbehandlingen mellan olika spridardesigner, att undersöka om det finns skillnader i oxidskikten från tillverkningstillstånd mellan olika spridardesigner eller från samma typ av spridare från olika leveranser samt att genom inspektionsundersökning systematiskt undersöka andra bränsleelementtyper under liknande driftförhållanden. Examensarbetet genomfördes hos Vattenfall Nuclear Fuel AB
"Watching. Being. Tracing." : Perspectives from doctoral students on tredje uppgiften and curation as a pedagogical tool
No full textTredje uppgiften is the Swedish principle that foregrounds the obligation of the researcher to communicate their research to a public audience. While engaging with this principle to produce a public exhibition in rural Sweden on ethnographic research methods, we found that the act of curation confronted us with the need to actively and critically reflect on how we use and operationalise research methods in practice. As such, this paper accounts for how, by adopting the principle of tredje uppgiften, curation emerges as a novel pedagogical tool that encourages students to consciously reflecton the methodological foundations of their research. We describe how, for us, this act of curation took two forms: first as a curation of knowledge content and then as a spatially informed selection and positioning of that curated knowledge. Drawing upon our own experiences, we suggest that curation confronts students with thorny questions about their research methods, questions that productively encourage methodological reflexivity and a deeper understanding of the research process, before suggesting how curation might be operationalised as a teaching tool in a variety of geographical contexts
Diffusion of macromolecules in extracellular matrix mimetic hydrogels : effect of size and charge
No full textSubcutaneous (SC) injection is the primary alternative to oral administration for therapeutic proteins and peptides. However, bioavailability and absorption rate are often variable and difficult to predict. Therefore, there is a need for new biorelevant and predictive SC in vitro methods. In this study we systematically investigate the effect of size and charge of a macromolecule on its partitioning and diffusion within extracellular matrix (ECM) mimetic hydrogels in order to gain insight on interactions with the components of the ECM affecting the absorption of a drug after SC injection. Hydrogels consisting of either agarose, cross-linked collagen and hyaluronic acid (HA) or cross-linked HA, were made and equilibrated in solutions of FITC-dextrans of varying sizes (4 to 150 kDa) and model peptides of varying net charge (+2 to +9). Partitioning and diffusion coefficients within gel and solution were determined using confocal laser scanning microscopy and fluorescence recovery after photo bleaching (FRAP), and compared to theoretical models. Generally, the partitioning and diffusivities within the gels decreased with increasing molecular weight, which was in good agreement with models describing the effect of obstruction of the gel network corrected for heterogeneity in the gel structure. The cationic peptides were enriched in the oppositely charged gels and their diffusivities decreased with increasing peptide charge. The experimental results were in semi quantitative agreement with an electrostatic model presented in this work
Building antifragile manufacturing systems through strategic technology integration
No full textPurpose: This study develops and validates, through expert consensus, a framework for achieving antifragility in manufacturing by strategically integrating modern digital technologies with capabilities that enable organizations to grow stronger through disruption. It moves beyond traditional resilience-focused approaches by emphasizing continuous adaptability, sustained growth and competitive advantage in an environment characterized by volatility and rapid technological change. Design/methodology/approach: Grounded in the dynamic capability perspective, the study synthesizes insights from an extensive literature review with the results of a Delphi study involving a panel of 14 industry and academic experts. The process identified and refined a set of critical supporting capabilities, including cross-functional governance, interoperability assessment and risk-responsive integration, that enable the alignment of digital transformation initiatives with antifragile objectives. Findings: Antifragility is positioned as a higher-order dynamic capability that transforms volatility into a driver of innovation and strategic renewal. The resulting expert-based framework maps emerging technologies such as artificial intelligence, the Internet of Things and big data analytics to specific sensing, seizing and transforming capabilities, providing a structured pathway for operationalizing antifragility in manufacturing contexts.Practical implicationsThe framework offers manufacturers a structured approach for aligning technology investments with antifragile objectives, ensuring that digital transformation enhances rather than undermines adaptability and growth. It encourages a phased, resource-aware implementation strategy that leverages disruptions as strategic assets, fostering both business continuity and long-term competitiveness. Originality/value: This research conceptualizes antifragility as a distinct and advanced capability in manufacturing and demonstrates how it can be purposefully developed through strategic technology integration. By combining theoretical grounding with expert validation, it bridges the gap between digital transformation and antifragility, offering a practical roadmap for turning uncertainty and variability into sources of competitive advantage
The Covid-19 pandemic in Sweden : Prolonged and unevenly distributed effects on the volume of pediatric anesthesia and surgery demonstrated by data from the Swedish Perioperative Register
No full textBackground In 2020, Covid-19 pushed Swedish health care to its limits regarding access to hospital beds and staffing. A previous investigation of the effects of the first wave of the pandemic in the spring of 2020 revealed a substantial reduction in elective pediatric surgery. The aim of the present study was to expand this analysis on a national and regional level during almost three years with Covid-19. Methods For this retrospective cohort study, routine data from all procedures in patients <16 years of age in 2019–2022 were extracted from the Swedish Perioperative Register. Data were analyzed according to level of care, type of surgery, procedure code and emergency or elective surgery. Results During 2020–2022, the number of surgeries registered was 19,944 fewer than expected as compared to pre-pandemic levels, i.e., a reduction of about 12%. Elective surgery showed a total reduction of 17% while emergency surgery was unaffected. The most dramatic decrease was found in county hospitals where elective surgery was reduced by 28% and the largest effect was found in Ear, Nose, and Throat/oral surgery (−34%). Patient age at the time of surgery did not show any notable differences in total, except for grommets insertion in 2021 and adenoidectomy in 2021 and 2022 compared to 2019. Conclusion The Covid-19 pandemic affected the number of surgical procedures in children for more than two years. Future studies of the long-term effects of the large number of canceled operations are warranted
Optimizing Railway Network using Randomized Shortest Path method : Application for Swedish Railway Data
No full textAs per data from Trans.se in 2024, Swedes traveled 708 million rides on public transportation. Data used in this study indicated the important role rail and other forms of public transport would play in national mobility, further demanding continuous changes to meet the growing demand of passengers and help to mitigate traffic jams. Different from road networks, where cars may alternate pathways the track is a fixed line and in some areas schedules may be fixed. Thus, it is impossible to escape this limitation, which makes the rail traffic require more control. European railways have been undergoing relatively higher restructuring of their operations over the past 20 years from a centralized, vertically integrated state-owned system to a separate rail system and independent railways (WheatandSmith[2008]). Sweden was among the first to implement this approach, and then other European countries did as well. The railway market liberalization opened the door for private operators into the sector and the expanded number of train services added to congestion as well as conflicts with scheduling. Conventional traffic methods suggest the use of a minimum path in order to minimize operating costs, however, this approach generally leads to over use of certain routes. This thesis applies the Randomized Shortest Path (RSP) algorithm which is helpful for evenly distributing the load between different routes by taking into account the exploitation of shortest paths and the possibility of alternative ones with a more durable and cost-effective way of managing railway lines. In the majority of routing models, travel cost is treated as the predicted travel time or distance and is assumed to be deterministic. Nonetheless, railway systems face uncertainties such as delays, operational disagreements and variable demand. In order to account for that variability, here we develop risk-averse pricing through Conditional Value at Risk (CVaR). CVaR, designed originally for financial risk management(Rockafellar and Uryasev[2002]) gives the expected cost in the worst case, representing α percent of the cost distribution. In transportation spaces, it means modeling not only the average performance of a route but the possibility of severe delays as well, which makes the model more robust to real-world uncertainties. This is a convex cost formulation and it can be used for optimization frameworks such as entropy-based models. Using CVaR in the entropy-regularized RSP model introduces alternative traffic assignment strategies that consider operating cost and also the risk of very large delays. Thus, the model is used to identify routes that are both efficient and reliable. To demonstrate the model’s utility within a manageable scope, this study focuses on two representative Origin-Destination (OD) pairs in the Swedish network: Stockholm C → Uppsala C(a high-frequency commuter route) and Stockholm C→ Malmö C(a long-distance route with multiple paths). Finally, this method has become a useful approach to optimizing railway traffic in complex and uncertain environments. 1.1 Purpose and Goals The thesis specifically focuses on finding a randomized shortest-path approach t optimize the railway networks using Swedish railway data. While a great deal of research has been done on stochastic shortest path methods applied to transportation networks, a limited empirical work has focused on optimizing the railway network in the literature. This study aims to address this gap by considering Dial’s algorithm (Dial[1971]) to point out its limitations and address these limitations with Akamatsu’s traffic assignment model. Then, develop the entropy-based route choice model described in a later section of his paper(Akamatsu[1996]) with the Conditional Value at Risk (CVaR) method to determine the cost parameters of the entropy model and optimize the railway network with the randomized shortest path methodology. The study is to practically implement this approach on the Swedish Railway network’s real-time data for a hard assessment of the system’s overall performance and operational feasibility. In other words, we can state that, how an entropy-based Randomized Shortest Path (RSP) framework be designed and applied to optimize traffic assignment in congested and uncertain railway networks? 1.2 Thesis Outline The thesis is organized into several chapters which concentrate on optimizing transportation networks. The second chapter is a literature review that contains the main concepts as well as up-to-date research on optimization methods for transportation. Traditional shortest path algorithms such as Dijkstra’s and A* are the first topics discussed and this chapter also presents the limits of such algorithms when practical railway lines are involved. The next chapter examines Dial’s algorithm, in which he applied "efficient paths" by minimizing backtracking. But it adds that cyclical movements are also present in real-world rail operations,which can also make Dial’s algorithm less relevant. Hence, the thesis tries to solve this problem by making the way to Akamatsu’s model better with more probabilistic routing by including cyclic paths and stochastic fluctuations of travel time. Then the chapter describes how the Akamatsu model is becoming more similar to the Entropy model, how it improves efficiency from a computational perspective and presents the computational foundation of the entropy-based RSP model. In addition, the back ground section discusses the network representation and Conditional Value at Risk (CVaR) method which is one of the most important cost estimation techniques, taking into account transportation time and congestion variability. Then the Bootstrap method,the Mann-Whitney U test and the Spearman’s Rank correlation methods are also discussed briefly. The next chapter of this writing is Methodology which begins with the process of data cleaning and preliminary analysis on the railway data provided by the Traffic Agency of Sweden. In the next section, the methodology explains how the entropy method is applied to these problems in Akamatsu’s entropy-based model. It describes how the entropy-based RSP model is formulated utilizing the risk-based cost estimation approach using Conditional Value-at-Risk (CVaR). Lastly, the chapter introduces evaluation metrics on different path selection strategies and helps to validate model accuracy. This also describes the application of the cost functions on the railway network and makes a case for the use of the risk-based optimization technique, CVaR. Here, the model’s assumptions and constraints and its methods to deal with railway related problems are elaborated. Implementation and Analysis( the fourth chapter) involves elaboration and validation of the model. It starts with data and gets the information from the railway network into analysis and interpretation. The preliminary analysis was conducted to identify the delay patterns of the dataset. The latter section of Chapter four presents the implementation of the model, how Akamatsu’s entropy-based RSP model is implemented, incorporating CVaR-based cost computation methods into the routing framework. The last part of this chapter describes how the simulation setup is executed under the various risk levels for testing scenarios and optimizing path selection and application of the bootstrap method to find the robustness of the findings.The Fifth chapter of the research is “Conclusions and Discussion” which discusses the main results and determines the efficacy of the entropy-based RSP on railway networks.It focuses on the way of varying risk profiles, modifying routing choices and assessing whether the risk-based optimization results in improved network performance. It also confirms these findings by using real data on railway delay and details the tradeoffs between optimization approaches. In the last chapter of the thesis, some ideas for future research could be explored.The study eventually suggests that Akamatsu’s entropy model provides a more flexible routing architecture while stressing the benefits of a risk-aware estimation approach like CVaR. Limitations of computational complexity are discussed and some potential improvements, such as exploring deep learning to enhance the scheduling behavior of trains to mitigate railway delays, are discussed
Design study of a high-brightness high-repetition rate thermionic injector for free-electron laser application. II. Gun technology
No full textThe SPring-8 Angstrom Compact free-electron LAser (SACLA) linear accelerator utilizes a dc gun with a thermionic cathode, known for delivering high beam quality, excellent operational stability, and low maintenance requirements. In the second part of our design study, we present a comprehensive beam dynamics analysis of the SACLA dc electron gun and outline a roadmap toward achieving submicrometer (0.1 mu m) beam emittance. We provide both analytical and numerical estimates of four key sources contributing to emittance growth: (i) image = charge effects on the cathode, (ii) nonlinear space-charge forces arising from imperfect beam edge geometry, (iii) aberrations in the accelerating field, and (iv) solenoid field aberrations due to longitudinal-transverse momentum exchange. The analysis yields a closed-form expression for the superposition of correlated emittance growth mechanisms, highlighting an "interference" term that amplifies the net emittance when space-charge and solenoid effects coexist. To address the challenge of emittance growth, we propose a compact hybrid magnet that ensures strong longitudinal confinement of the magnetic field. This confinement allows placement of the hybrid magnet in close proximity to the gun exit, thus mitigating emittance growth effectively, while having a negligible magnetic field on the cathode. The hybrid magnet design is achieved by symmetrically positioning permanent ring magnets on either side of a solenoid, enabling fine control over the field distribution and "squeezing in" it longitudinally. Our findings offer new insights applicable to low-voltage continuous-wave very high-frequency guns and superconducting radio-frequency electron guns
Covariate selection strategies and estimands - A review of current practice of risk factor analysis from a causal perspective
No full textIn applied epidemiological studies, the term “risk factor” is used synonymously with both predictors and causal factors for disease, although causal aims of explanatory analyses are rarely stated explicitly. Consequently, the concepts of explaining and predicting are conflated in many risk factor analyses, where data-driven variable selection, not suitable for causal inference, is common. We review the current practice of evaluating risk factors with regression analysis in three medical journals, focusing on the definition of risk factors, covariate selection strategies, and interpretation of regression coefficients. In simulations, we compare common practices to a causal approach using a data learner that mimics data from a study investigating risk factors for COVID-19 severity among patients with Multiple Sclerosis. The implied meaning of the term’ risk factor’ varies across the reviewed articles, but many authors implicitly give a causal definition of the term. In the articles, logistic regression is the most frequently used model, from which the coefficients are taken as effect estimates of the risk factors under study. We identify three common covariate selection strategies: i) adjusting for a pre-specified set, ii) stepwise selection, and iii) univariable pre-filtering. The simulation study illustrates the limitations of the current practice compared to the estimation of a marginal causal odds ratio by highlighting the difference between the conditional odds ratio and the marginal odds ratio. When considering risk factors as causal factors, the effect of interest should be clearly defined, and variables should be selected based on the underlying causal structure