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Deep learning reconstruction for 129Xe diffusion-weighted MRI enables use of natural abundant Xenon and improved image acceleration
Get PDFPurpose
(i) To assess whether 129Xe apparent diffusion coefficient (ADC) and diffusive length scale (LmD) metrics are quantitatively preserved with deep learning (DL) accelerated acquisition and reconstruction and (ii) to evaluate the feasibility of 129Xe diffusion weighted imaging with natural-abundance xenon at increased acceleration factors.
Methods
Twenty three-dimensional compressed sensing (CS) accelerated 129Xe DW MRI datasets were gathered from a cohort of patients with asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Images were retrospectively reconstructed with DL based CS, denoising and de-ringing reconstruction, and compared to conventional CS. ADC and diffusive length scales (LmD) were assessed and compared between conventional CS and DL reconstructions. Prospectively acquired DL reconstruction was then assessed in three healthy volunteers who underwent 129Xe DW MRI with both natural-abundance and enriched xenon mixes.
Results
DL reconstruction qualitatively improved the sharpness, SNR and image quality of 129Xe DW images. In the retrospective study, DL reconstruction produced a slight bias in ADC (5.4%) and LmD (0.8%) values when compared with conventional CS reconstruction. In the prospective study, DL reconstruction significantly improved the SNR of natural-abundance xenon images and produced ADC and LmD values comparable to those achieved with 129-enriched xenon.
Conclusion
DL-based CS, denoising and de-ringing significantly improves SNR and image sharpness in 3D 129Xe diffusion-weighted MRI while exhibiting a slight bias in ADC and LmD. This approach enables the use of natural-abundance xenon and higher acceleration factors, offering substantial cost reduction and improved clinical feasibility for hyperpolarized 129Xe lung morphometry
AI implementation in pediatric radiology for patient safety: a multi-society statement from the ACR, ESPR, SPR, SLARP, AOSPR, SPIN
No full textArtificial intelligence (AI) has potential to revolutionize radiology, yet current solutions and guidelines are predominantly focused on adult populations, often overlooking the specific requirements of children. This is important because children differ significantly from adults in terms of physiology, developmental stages, and clinical needs, necessitating tailored approaches for the safe and effective integration of AI tools. This multi-society position statement systematically addresses four critical pillars of AI adoption: (1) regulation and purchasing, (2) implementation and integration, (3) interpretation and post-market surveillance, and (4) education. We propose pediatric-specific safety ratings, inclusion of datasets from diverse pediatric populations, quantifiable transparency metrics, and explainability of models to mitigate biases and ensure AI systems are appropriate for use in children. Risk assessment, dataset diversity, transparency, and cybersecurity are important steps in regulation and purchasing. For successful implementation, a phased strategy is recommended, involving early pilot testing, stakeholder engagement, and comprehensive post-market surveillance with continuous monitoring of defined performance benchmarks. Clear protocols for managing discrepancies and adverse incident reporting are essential to maintain trust and safety. Moreover, we emphasize the need for foundational AI literacy courses for all healthcare professionals which include pediatric safety considerations, alongside specialized training for those directly involved in pediatric imaging. Public and patient engagement is crucial to foster understanding and acceptance of AI in pediatric radiology. Ultimately, we advocate for a child-centered framework for AI integration, ensuring that the distinct needs of children are prioritized and that their safety, accuracy, and overall well-being are safeguarded
The accelerated propagation of pulsed gravity currents
Get PDFPulsed gravity currents are generated by the sequential release of dense material into a lighter ambient. We investigate the dynamics of pulsed gravity currents using physical scale experiments, two-dimensional depth-averaged shallow water equation (SWE) based models and three-dimensional lattice Boltzmann method (LBM) simulations. Integrating these results we show for the first time that short duration pulsed releases generate intrusive layers, which accelerate front propagation relative to an instantaneously released current of the same total volume. Conversely, a long delay time between pulses produces a current that propagates slower than an equivalent instantaneous release. This finding is supported by physical experiments and depth-resolving LBM simulations. The depth-resolving simulations show that intrusions in pulsed flows experience less drag resistance than those generated by instantaneous releases. The depth-averaged model considered in the present study does not accurately capture the intrusive flow dynamics of pulsed currents. However, the limitations of the finite-depth SWE model may be mitigated by extensions to incorporate entrainment and density stratification. The results also motivate further research into the impact of buoyancy Reynolds number and channel slope on the propagation of pulsed currents
The 3d Mixed BF Lagrangian 1-Form: A Variational Formulation of Hitchin’s Integrable System
Get PDFWe introduce the concept of gauged Lagrangian 1-forms, extending the notion of Lagrangian 1-forms to the setting of gauge theories. This general formalism is applied to a natural geometric Lagrangian 1-form on the cotangent bundle of the space of holomorphic structures on a smooth principal G-bundle P over a compact Riemann surface C of arbitrary genus g, with or without marked points, in order to gauge the symmetry group of smooth bundle automorphisms of P. The resulting construction yields a multiform version of the 3d mixed BF action with so-called type A and B defects, providing a variational formulation of Hitchin’s completely integrable system over C. By passing to holomorphic local trivialisations and going partially on-shell, we obtain a unifying action for a hierarchy of Lax equations describing the Hitchin system in terms of meromorphic Lax matrices. The cases of genus 0 and 1 with marked points are treated in greater detail, producing explicit Lagrangian 1-forms for the rational Gaudin hierarchy and the elliptic Gaudin hierarchy, respectively, with the elliptic spin Calogero–Moser hierarchy arising as a special subcase
From sales exaptation to digital transformation: Value creation from remote selling
Get PDFDigital transformation of sales practices was accelerated during the pandemic as it necessitated a rapid shift to remote selling for many organizations. However, traditional sales' reliance on onsite visits, collaborative sales team meetings, and in-person interactions with customers have raised questions on the viability of remote selling in the B2B sales context. This qualitative study explores how sales organizations rapidly responded to these disruptions to create value for remote buyers. Through in-depth interviews with sales managers engaged in remote selling, we reveal new value creation mechanisms via digital channels, enhancing both sales efficiency and customer relationships, the realization of which is followed by organizations' deliberate efforts to assimilate remote selling. We argue this rapid shift can be better understood through evolutionary concepts of exaptation and subsequent adaptation, providing insights into organizational response to radical environmental changes. More specifically, we propose a processual framework where crisis-induced salesforce exaptation prompts organizations to accelerate technology adoption and capability development, which in turn catalyzes organizational changes to propel businesses into digital transformation trajectories. Our research contributes to the literature on crisis-driven innovation and exaptation theory for analyzing rapid transformations. We offer practical insights to address the challenges of incorporating digital technologies into sales structures
Understanding novel biocomposites comprising of short cellulose fibres in a hybrid cellulose/silk fibroin matrix
Get PDFBiopolymer blends offer a promising route to tunable, high-performance biomaterials, yet their potential in reinforced composites remains underexplored. This study investigates biocomposites produced by reinforcing a
hybrid biopolymer matrix (90:10 cellulose:silk fibroin) with randomly oriented short cotton fibres and varying
the reinforcement weight percentage. A pure cellulose matrix was tested for comparison. The composites were
characterised using X-ray diffraction (XRD), density analysis, tensile testing, optical microscopy, scanning
electron microscopy (SEM), and acoustic insulation analysis. Optimal hybrid composites with 50 vol%
reinforcement exhibited superior performance to pure cellulose, achieving a Young’s modulus of 3.3 ± 0.3
GPa, strain at failure of 1.4 ± 0.2%, and maximum tensile strength of 42 ± 6 MPa. These enhancements
were attributed to the hybrid matrix’s reduced viscosity and improved solvation capacity allowing higher fibre
loading and stronger interfacial adhesion. In addition, the hybrid matrix’s greater extensibility enabled more efficient stress transfer to the fibres, maximising mechanical performance. Fibre content was identified as the
primary driver of material modulus, underscoring the critical role of reinforcement. Flock content was then
shown to correlate with improved acoustic insulation performance which led to a maximum average acoustic
transmission loss of 47 ± 7 dB in hybrid samples compared to 29 ± 4 dB in cellulose samples. This work
demonstrates the viability of hybrid biopolymer blends for creating low-density, high-performance materials
from short-fibre textile waste with sustainable applications in insulative structural engineering
Separating the genetic and environmental drivers of body temperature during the development of endothermy in an altricial bird
Get PDFWhen altricial birds hatch, they are unable to regulate their own temperature, but by the time they fledge they are thermally independent. Early-life conditions have been shown to be an important factor contributing to fitness. However, it is currently unknown to what extent body temperature during endothermy development is driven by genetic variation or by the early environment. We use thermal images of cross-fostered house sparrows (Passer domesticus) throughout the nestling period to separate genetic and environmental drivers of body temperature. We estimated negligible heritability of body temperature at all ages. We further found that there are effects from the natal environment that carry over into the late nestling stage. A correlation between the early- and mid-nestling periods was explained by the natal environment, and during this period body temperature and growth followed independent developmental trajectories. Furthermore, higher body temperature was under viability selection, independent of body mass. We, therefore, demonstrate that the natal environment influences future offspring phenotype via a novel measure; body temperature. Our study provides a novel investigation into the environmental and genetic drivers of body temperature variation in a wild bird, furthering our understanding of how traits evolve
Inter-tropical African precipitation regime shifts dominated by tropical easterly jet
Get PDFSince the 1990s, inter-tropical Africa (ITA) has experienced consecutive calamitous droughts during the boreal spring. Although the observed precipitation regime changes have been attributed to tropical Indian Ocean-western Pacific warming and/or tropical Pacific La Niña-like cooling, the model-projected past-to-future widespread wetting response to anthropogenic warming overshadows qualitative attributions of decadal shifts in historical precipitation regimes and the reliability of near-term projections. The causes of ITA precipitation regime shifts and the likelihood of their future continuation remain unclear. Here, we reveal that the observed monopolar precipitation changes in ITA are primarily driven by the tropical easterly jet (TEJ)-dominated pattern, with a secondary contribution from the intertropical convergence zone (ITCZ)-mediated pattern. The Indo-Pacific warming-induced TEJ strengthening favors a monopolar drying trend from 1950 to 2022, while the northward-shifted ITCZ drives a west drying-east wetting dipolar pattern. Considering an observational TEJ constraint, an accelerated TEJ with an amplitude of -2 standard deviations could cause an almost threefold increase in extreme drying trends in the near term (2026–2045). Instead, ITA could face a higher likelihood of extreme wetting tendency due to a near-term TEJ weakening. Our findings underscore the importance of realistic TEJ simulations in enhancing confidence in future precipitation projections across hydroclimate-vulnerable Africa
Assessment of behavioural modification techniques on particle-laden turbulent pipe flows
Get PDFIn this study, particle-laden turbulent pipe flows are predicted using direct numerical simulation of the fluid flow in combination with Lagrangian particle tracking and a deterministic energy-based particle agglomeration model, with a particular focus on predicting and elucidating the dynamics of particle–particle interactions. The models used, which were developed and validated in the present work, enhance our understanding of these flows, particularly in regards to the processes which lead to particle collision and agglomeration. The energy-based agglomeration technique is used together with four-way coupling between the particles and the fluid flow to predict particle aggregation due to collision interactions within the flow. Additionally, the impact of behavioural modification techniques, which influence particle dispersion, agglomeration and ultimately particle deposition, is investigated by varying influential parameters such as the temperature and Reynolds number of the flow, and the reduced surface potential, inverse Debye length, Hamaker constant and coefficient of restitution which govern particle–particle interactions. It is concluded that electric double layer repulsion exerts little influence on collision and agglomeration behaviour, attributable to the particle diameters examined being higher in comparison to the effective range of these forces. The study further demonstrates that the restitution coefficient has a significant influence on the behaviour of particle agglomeration, with a decrease in the coefficient resulting in increased aggregation rates. Hamaker constant and Reynolds number variations also both lead to major impacts on particle–particle interaction, with collision and agglomeration events occurring more frequently for increased Hamaker constant and Reynolds number
Reluctant acceptance:Exploring implementation and contextual factors influencing the acceptability of a newly implemented low emission zone in a UK urban setting. Urban Transitions
Get PDFLow emission zones (LEZ), known as Clean Air Zones (CAZ) in England, aim to improve air quality by restricting the movement of the most polluting vehicles in urban areas. Despite their increasing deployment across European cities, they remain a contentious policy amongst populations, with suggestions that they have adverse impacts, such as an inequitable impact on different communities. Few studies have explored how communities and businesses are impacted by the introduction of a CAZ. The current study explored adaptations made and attitudes towards the Bradford CAZ in the first year of implementation. Semi-structed interviews were conducted with 20 workers in professions which had the potential to be directly affected by the CAZ (e.g. bus and taxi firms, local tradespeople), and eight diverse focus groups held with 51 residents, between March - August 2023. Thematic analysis identified key themes inductively. Overall, respondents suggested that the CAZ worked as intended, encouraging businesses to upgrade vehicles. Mitigations such as exemptions and grants were used, but were not felt to be enough to support smaller businesses. The majority of participants supported the CAZ, but there were strong negative attitudes including dissatisfaction with how the intervention worked, feelings of unfairness, lack of trust in those implementing the intervention and issues with the communication of the policy. Policies such as CAZ operate within a complex system and it is important to systematically capture wider impacts, both positive and negative. Ultimately, these factors impact on political popularity, which will in turn influence the likely continued implementation of such policies at scale
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