Publikationer från Uppsala Universitet
Not a member yet
127603 research outputs found
Sort by
Target tracking using robust sensor motion control
No full textWe consider the problem of tracking moving targets using mobile wireless sensors (of possibly different types). This is a joint estimation and control problem in which a tracking system must take into account both target and sensor dynamics. We make minimal assumptions about the target dynamics, namely only that their accelerations are bounded. We develop a control law that determines the sensor motion control signals so as to maximize target resolvability as the target dynamics evolve. The method is given a tractable formulation that is amenable to an efficient search method and is evaluated in a series of experiments involving both round-trip time based ranging and Doppler frequency shift measurements
Diffusion of Affibody molecules in extracellular matrix mimetic hydrogels and the effect of albumin binding
No full textAffibody molecules are protein ligands, that due to their small size (6-19 kDa) and high target affinity exhibit favourable properties for tumour uptake valuable in diagnostic imaging and therapeutic applications. Fusion to a high affinity albumin binding domain (ABD) has been shown to improve circulatory half-life and biodistribution. However, the effect of molecular design is not obvious to predict and in vitro methods to evaluate their transport properties in physiologically relevant environment are needed. In this work we investigated the diffusivities (D) of Affibody molecules, with systematically varied molecular design, in solution and within extracellular matrix mimetic hydrogels composed of either agarose or collagen and hyaluronic acid (COL-HA) using fluorescence recovery after photobleaching. Furthermore, the effect of presence of human serum albumin (HSA) was evaluated. The correlation between D of the tested Affibody molecules in solution and their molecular weight (Mw) was weak, indicating that propensity to form reversible oligomers and the size of the oligomers are more important for their diffusion properties than Mw of the monomer. Positively charged Affibody molecules were enriched in polymer-rich domains of the COL-HA gel accompanied by a decrease in D as a result of electrostatic interactions. Binding to HSA by Affibody molecules containing an ABD was evident as a decrease of D when HSA was present. In COL-HA gels HSA-binding reduced the effect of electrostatic interactions effectively facilitating the transport of those compounds. In conclusion, molecular design especially inclusion of an ABD affected the transport properties of the tested Affibody molecules
Efficient finite difference modeling of infrasound propagation in realistic 3D domains : Validation with wind turbine measurements
No full textWe present a high-fidelity simulation tool for accurate acoustic modeling across a wide range of applications. The numerical method is based on diagonal-norm Summation-By-Parts (SBP) finite-difference operators, which guarantee linear stability on piecewise curvilinear multi-block grids. Realistic three-dimensional atmospheric and topographic data are directly incorporated into the simulations, and the solver is implemented in CUDA to achieve high computational efficiency. Verification is performed through convergence studies against highly resolved benchmark problems in both two and three spatial dimensions, while validation is carried out using high-quality infrasound measurements from two modern wind farms in Sweden. The results show that modern, large-scale wind turbines generate infrasound levels significantly higher than those reported for older, smaller turbines. These findings advance the understanding of the acoustic characteristics of contemporary wind turbines and provide important guidance for assessing their potential environmental and societal impacts
Enabling mixed-precision in spectral element codes
No full textMixed-precision computing has the potential to significantly reduce the cost of exascale computations, but determining when and how to implement it in programs can be challenging. In this article, we propose a methodology for enabling mixed-precision with the help of computer arithmetic tools, roofline model, and computer arithmetic techniques. As case studies, we consider Nekbone (Nek5000 developers), a mini-application for the Computational Fluid Dynamics (CFD) solver Nek5000 (Fischer et al.), and a modern Neko (Jansson et al., 2024) CFD application. With the help of the Verificarlo (Denis et al., 2016) tool and computer arithmetic techniques, we introduce a strategy to address stagnation issues in the preconditioned Conjugate Gradient method in Nekbone and apply these insights to implement a mixed-precision version of Neko. We evaluate the derived mixed-precision versions of these codes by combining metrics in three dimensions: accuracy, time-to-solution, and energy-to-solution. Notably, mixed-precision in Nekbone reduces time-to-solution by roughly 1.62x and energy-to-solution by 2.43x on MareNostrum 5, while in the real-world Neko application, the gain is up to 1.3x in both time and energy, with the accuracy that matches double-precision results
Ageing mitigation of 21700 Li-ion cylindrical batteries for heavy duty BEVs through forced air and immersion cooling strategies in Nordic climate zones
No full textA Battery Electric Vehicle (BEV) pack requires an intelligent and integrated arrangement of the thermal management system (TMS). While previous studies have investigated TMSs independently, we here make a comparative analysis between air and immersion TMSs tailored for both sub-zero and peak summer temperatures, mimicking Nordic climate zones. A parametric sweep of flow and thermal design parameters using laminar and turbulent flow regimes is performed. These ambient conditions and loading pattern corresponding to a heavy BEV constitute the basis of the comparison. The analysis is based on various well-defined key performance indicators. Moreover, the air based TMS requires high Re flows to give the best performance, while immersion TMS can perform well in a laminar range. It was deduced that low Re (126) and high Re (>3000) may not give better thermal performance, and it is therefore crucial to design the TMS within the proposed flow and thermal design sets. In contrast to previous work, where the main focus has been on the cooling efficiency or steady-state performances, this work extends the horizon to investigate the effect of these TMSs on ageing behaviour to quantify long-term benefits on battery reliability and safety. The coupled ageing-thermal battery model was simulated for 1000 cycles for different cases, showcasing 3.4 % improvement in SOH for immersion TMS compared to the air based TMS. Thus, the climate resilient TMS aids in heat management, and the coupled model is thereby shown to help estimate the battery SOH
Beyond linear progress : Towards a material-temporal understanding of infrastructural unmaking
No full textThe implementation of low-carbon futures requires both the assembling of new technologies, and practices, as well as the 'unmaking' of extant high-carbon infrastructures. Here, we bring together geographical, STS, anthropological, and sociological thinking on time to re-conceptualise such processes of unmaking. We argue that a focus on temporalities is especially pertinent to the unmaking of material energy infrastructure, as the emergence of fossil fuel societies has also enabled a particular temporality of the future to take hold; one that is linear, future-oriented, and full of promise. The unmaking of energy infrastructures will likely rub up against this temporal form of thinking that dominates modern life. By drawing on three temporal concepts - ruination, suspension, and lingering - we explore how we can conceptualise the temporal dimensions of unmaking material infrastructures more explicitly, and differently. Through foregrounding the multifaceted interactions between the legacies of the past, the realities of the present, and the possibilities of the future we put forward an understanding of infrastructural unmaking and lowcarbon futures that seeks to go beyond the confines of linear progress
Nickel : Geochemistry, biochemistry and its role in chemical and biological evolutions
No full textNickel is a versatile element that plays critical roles in Earth's geological and biological evolution, from the depths of the magmatic mantle to the complexity of prebiotic chemistry. While it is not considered the sole catalyst for the origin of life, recent research suggests that Ni may have had a more profound role than traditionally recognized. This review synthesizes Ni isotope geochemistry, biology, and prebiotic chemistry, exploring how Ni isotope variations offer new insights into magmatic processes, hydrothermal systems, and the cycling of Ni through Earth's lithosphere and hydrosphere. We summarize the pathways of Ni in oceanic environments, highlighting its influence on biogeochemical cycles and microbial metabolisms that shape global ecosystems. Furthermore, we examine the essential roles of Ni in biological systems, focusing on its function as a catalytic metal in enzymes crucial for nitrogen and carbon cycling. Extending to the prebiotic world, we evaluate Ni's potential in catalyzing life's earliest chemical reactions, including the polymerization of amino acids and the fixation of CO2, possibly driven by unique metal-ligand interactions. Our comprehensive review positions Ni as a pivotal element across geological timescales and environments, underscoring its relevance to both planetary and biochemical processes
Depression in pregnancy : A multinational prospective cohort study
No full textIntroduction: Depression in pregnancy is associated with adverse outcomes for both mother and baby. Estimates of the prevalence of depression in pregnancy vary considerably across low-and middle-income countries. We set out to prospectively determine the prevalence of depression in pregnancy in two low-and middleincome countries, and to investigate its association with adverse pregnancy outcomes. Methods: This multinational prospective cohort study was conducted in Pakistan and South Africa from 2021 to 2023 in two tertiary referral centres. The Edinburgh Postnatal Depression Scale was administered to women between 20-and 34-weeks' gestation. Women were followed up and pregnancy outcomes collected. A Bayesian model accounting for the sensitivity and specificity of the Edinburgh Postnatal Depression Scale was used to estimate prevalence. Results: 1537 participants were recruited. The adjusted prevalence of depression in pregnancy was 17.1 % (95% credible interval [CrI] 13.3 % - 21.1 %). Estimates varied across sites, in Pakistan, 10.8 % (95% CrI 7.7% - 14.3 %), and in South Africa, 25.9% (95% Crl 20.8 %-31.1 %) of women experienced depression in pregnancy. There were no associations between screening positive on the Edinburgh Postnatal Depression Scale (score >= 11) and spontaneous preterm birth (adjusted odds ratio [aOR] 1.20 95 % confidence interval [CI] 0.79-1.83), low birthweight (aOR 1.25 95 % CI 0.91-1.72), or admission to a special care/neonatal intensive care unit (aOR 0.95 95% CI 0.59-1.52). Conclusion: Within our study cohort, spanning two centres in Pakistan and South Africa, one in six women experienced depression in pregnancy. Reassuringly, depression was not associated with an increase in adverse pregnancy outcomes; spontaneous preterm birth, low birthweight or admission to neonatal intensive care/ special care nursery. Our study provides robust estimates of the burden of depression in pregnancy in two low-and middle-income countries; an important first step in addressing maternal mental health
Change in cardiac troponin T to differentiate acute from chronic myocardial injury in the Emergency Department.
No full textINTRODUCTION: Persistently elevated cardiac troponin (cTn) values are observed in many patients with suspected acute coronary syndrome (ACS) in the absence of myocardial infarction and may reflect underlying cardiac disease. Chronic myocardial injury is defined where cTn values are elevated and vary by ≤ 20 % on sequential measurements. We aimed to evaluate whether these criteria are reliable over short intervals applied in accelerated diagnostic pathways. METHODS: In a secondary analysis of a prospective, multi-centre cohort study of patients with suspected ACS, cTnT was measured at presentation, 1, 2 and 6-36 h, and the final diagnosis adjudicated according to the Fourth Universal Definition of Myocardial Infarction. Two criteria for chronic myocardial injury were compared: a relative change in cTn of ≤ 20 % and an absolute change < 3 ng/L, and the findings externally validated. RESULTS: At presentation cTnT was elevated in 242 of 1,000 (25 %) patients (73 years, 42 % female), of whom 94/242 (39 %), 13/242 (5 %) and 137/242 (56 %) had myocardial infarction, acute or chronic myocardial injury, respectively. A relative change of ≤ 20 % misclassified 58 % (59/101) and 49 % (48/98) of patients with a final diagnosis of acute myocardial injury or infarction at 1 and 2 h, respectively, whereas an absolute change of < 3 ng/L misclassified 22 % (22/101) and 15 % (15/98). In the validation cohort (n = 621), the relative and absolute change criteria at one hour misclassified 43 % (13/30) and 17 % (5/30) of those with myocardial infarction. CONCLUSIONS: Chronic myocardial injury cannot reliably be differentiated from acute myocardial injury or infarction by recommended criteria over short remeasurement intervals in the Emergency Department. Longer intervals between sampling and absolute rather than relative criteria may reduce the risk of misclassification
Mechanical properties and thermal stability of refractory metal-alloyed (Al V)N-based high-entropy nitrides and oxynitrides
No full textThis study explores the thermal stability and mechanical properties of (Al,V)-based high-entropy sublattice nitride (HESN) and oxynitride (HESON) coatings alloyed with various refractory metals, including Ti, Cr, Mo, W, Hf, and Zr. Through systematic annealing treatments at 800 degrees C, we examine the influence of alloying elements on the hardness and indentation modulus of these coatings. The results show that coatings alloyed with Ti-Hf-Cr, TiHf-W, Zr-Hf-Cr, and Ti-Cr-W exhibit excellent retention of mechanical properties under prolonged thermal exposure. In particular, the Ti-Hf-W-alloyed (Al,V)N and its oxynitride variant maintain the highest hardness of similar to 32 GPa during 50 h vacuum annealing at 800 degrees C. Conversely, the Cr-Mo-W-alloyed variants exhibit significant degradation and the formation of an Me2N phase. X-ray diffraction analyses reveal changes in preferred crystallographic orientations and the emergence of fcc-structured domains, influencing mechanical behavior. Despite their thermal degradation, the Cr-Mo-W-alloyed (Al,V)N showed the most promising fracture toughness behavior. The findings highlight the importance of careful selection of alloying elements and compositions to optimize the performance of HESN and HESON coatings for high-temperature applications. This research provides valuable insights into the underlying mechanisms affecting the thermal and mechanical properties of advanced coatings, paving the way for future advancements in materials designed for extreme environments