2,099 research outputs found

    Kinetic magnetised transport in ablating laser-produced plasmas

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    Irradiation nonuniformity is a major source of degrading target performance at ongoing spherical- direct-drive experiments at OMEGA [2, 3] and polar-direct-drive experiments at the National Ignition Facility [4]. Laser energy is deposited in the underdense plasma and transported, through the conduction zone, towards the cold target surface. The damage of irradiation nonuniformity is mitigated by thermal smoothing in this conduction zone. Heat flow, tangen- tial to the target surface, attenuates perturbation amplitudes before they imprint themselves onto the target surface, whereupon they seed hydrodynamic instabilities. Epperlein [5] showed that nonlocal suppression of the heat flux tangential to the target surface may severely reduce the thermal smoothing efficiency relative to local models. However, in this transverse direction, nonlocal suppression of the heat flux also competes with the magnetised Righi-Leduc heat flow [6]. Furthermore, nonlocality modifies the thermal response time of the plasma [7], which becomes pertinent when considering perturbations seeded by rapidly varying laser speckles of an optically smoothed beam [8]. In this thesis, I study the effects of how nonlocal modification of the lateral transport, the temporal response and magnetised transport may combine and interplay to influence thermal smoothing. Two dimensional Vlasov-Fokker-Planck simulations of the conduction zone of planar ablating targets are performed. These simulations are novel in the inclusion of both ablation and mag- netic field within a kinetic study of thermal smoothing. The key result is that magnetic fields may significantly reduce thermal smoothing efficiency. A novel phase inversion is discovered, caused by the magnetised Righi-Leduc heat flow. It is shown that magnetised transport effects become important even for small Hall parameters (ωτ <0.05). The thermal smoothing of a time evolving speckle-like perturbation is investigated. Self- generated magnetic fields are found to significantly affect the plasma temporal response. The perturbation correlation time may grow to more than double the laser heating value as a result of magnetic field build-up within the conduction zone.Open Acces

    AMCIS 2006 Panel Report: The Web as a Digital Reflection of Reality

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    The web is increasingly relied upon as a reflection of reality, which raises a number of key issues not yet fully recognized or articulated, warranting further study. This new digital reality and the unprecedented capabilities it embodies in terms of searchability, aggregatability, temporal persistence, and so on, give rise to great challenges in the areas of Digital Identity Management, Social Impacts, Currency and Accuracy of Digital Data, Distorting Factors, Legal Issues and Implications, among others, that are only just becoming recognized and articulated. This paper reports on a panel exploring these issues and speculating creatively on how they might be addressed in IS academic research by adopting a fundamental information processing approach to design, incorporating analogs from evolutionary biology, for example

    Longitudinal association of conduct and emotional problems with school exclusion and truancy: A fixed effect analysis of the UK Millennium Cohort Study

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    BACKGROUND: There is a need for causally stronger research on the association between child mental health and school exclusion and truancy. This study examines school exclusion and truancy in relation to both conduct and emotional problems and considers these problems both as predictors and as outcomes of school exclusion and truancy. METHOD: The sample included 15,236 individuals from the Millennium Cohort Study, a UK longitudinal birth cohort study. Conduct and emotional problems were assessed from childhood to adolescence (age 7, 11, 14 and 17 years), and reports of school exclusion and truancy were collected at age 11 and 14. Fixed effect analyses were used. RESULTS: Increases in conduct problems and emotional symptoms were associated with subsequent exclusion (OR 1.22, [95% CI 1.08-1.37] and OR 1.16, [1.05-1.29], respectively). Emotional symptoms, but not conduct problems, predicted truancy (OR 1.17, [1.07-1.29]). These estimates were similar for males and females. Exclusion was associated with an increase in conduct problems at age 14 (0.50, [0.30-0.69]), and for males, it was associated with an increase in emotional symptoms both at age 14 (0.39, [0.12-0.65]) and 17 (0.43, [0.14-0.72]). Truancy was associated with an increase in conduct problems at age 14 (0.41, [0.28-0.55]), and for females also at age 17 (0.22, [0.03-0.42]), and it was associated with increased emotional symptoms at age 14 (0.43, [0.25-0.62]) and 17 (0.44, [0.21-0.66]), which was similar for males and females. CONCLUSION: Results indicate a bidirectional association between emotional symptoms and school exclusion and truancy, as an increase in these symptoms was associated with later truancy and exclusion, and emotional symptoms increased following both school events. For conduct problems, the association was bidirectional for school exclusion, but unidirectional for truancy as these symptoms did not lead to truancy, but an increase in conduct problems was observed after both exclusion and truancy

    A nonlinear and time-dependent leak current in the presence of calcium fluoride patch-clamp seal enhancer [version 1; peer review: 2 approved with reservations]

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    Automated patch-clamp platforms are widely used and vital tools in both academia and industry to enable high-throughput studies such as drug screening. A leak current to ground occurs whenever the seal between a pipette and cell (or internal solution and cell in high-throughput machines) is not perfectly insulated from the bath (extracellular) solution. Over 1 GΩ seal resistance between pipette and bath solutions is commonly used as a quality standard for manual patch work. With automated platforms it can be difficult to obtain such a high seal resistance between the intra- and extra-cellular solutions. One suggested method to alleviate this problem is using an F− containing internal solution together with a Ca2+ containing external solution — so that a CaF2 crystal forms when the two solutions meet which ‘plugs the holes’ to enhance the seal resistance. However, we observed an unexpected nonlinear-in-voltage and time-dependent current using these solutions on an automated patch-clamp platform. We performed manual patch-clamp experiments with the automated patch-clamp solutions, but no biological cell, and observed the same nonlinear time-dependent leak current. The current could be completely removed by washing out F− ions to leave a conventional leak current that was linear and not time-dependent. We therefore conclude fluoride ions interacting with the CaF2 crystal are the origin of the nonlinear time-dependent leak current. The consequences of such a nonlinear and time-dependent leak current polluting measurements should be considered carefully if it cannot be isolated and subtracted

    Stakeholder perspectives towards diagnostic artificial intelligence: a co-produced qualitative evidence synthesis

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    Background: Diagnosis is a cornerstone of medical practice. Worldwide, there is increased demand for diagnostic services, exacerbating workforce shortages. Artificial intelligence (AI) technologies may improve diagnostic efficiency, accuracy, and access. Understanding stakeholder perspectives is key to informing implementation of complex interventions. We systematically reviewed the literature on stakeholder perspectives on diagnostic AI, including all English-language peer-reviewed primary qualitative or mixed-methods research. Methods: We searched PubMed, Ovid MEDLINE/Embase, Scopus, CINAHL and Web of Science (22/2/2023 and updated 8/2/2024). The Critical Appraisal Skills Programme Checklist informed critical appraisal. We used a ‘best-fit’ framework approach for analysis, using the Non-adoption, Abandonment, Scale-up, Spread, Sustainability (NASSS) framework. This study was pre-registered (PROSPERO CRD42022313782). Findings: We screened 16,577 articles and included 44. 689 participants were interviewed, and 402 participated in focus groups. Four stakeholder groups were described: patients, clinicians, researchers and healthcare leaders. We found an under-representation of patients, researchers and leaders across articles. We summarise the differences and relationships between each group in a conceptual model, hinging on the establishment of trust, engagement and collaboration. We present a modification of the NASSS framework, tailored to diagnostic AI. Interpretation: We provide guidance for future research and implementation of diagnostic AI, highlighting the importance of representing all stakeholder groups. We suggest that implementation strategies consider how any proposed software fits within the extended NASSS-AI framework, and how stakeholder priorities and concerns have been addressed

    Venous injection of a triphasic calcium-based implant in a sheep model of pulmonary embolism demonstrates minimal acute systemic effects.

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    PURPOSE Implant leakage is the most common complication of vertebral augmentation. Alternative injectable materials must demonstrate intravascular safety comparable to or better than polymethyl methacrylate (PMMA). This study assessed the systemic effects of a triphasic calcium-based implant or PMMA injected directly into the femoral vein in a large animal model designed to mimic severe intravascular implant leakage. METHODS Six skeletally mature female sheep were randomly assigned (n = 3) to either the PMMA or the triphasic implant (AGN1, composition: calcium sulfate, β-tricalcium phosphate, brushite) treatment group. Femoral veins of each sheep were directly injected with 0.5 mL of implant material to mimic leakage volumes reported during PMMA vertebroplasty. To compare acute systemic effects of the materials, cardiovascular parameters, laboratory coagulation markers, and calcium and sulfate serum levels were monitored for 60 min after implant injection. Thrombotic and embolic events were evaluated by radiologic imaging, necropsy, and histopathology. RESULTS Heart rate, systemic arterial blood pressure, arterial oxygenation, arterial carbon dioxide content, and coagulation markers remained within physiological range after either AGN1 or PMMA injection. No blood flow interruption in the larger pulmonary vessels was observed in either group. Lung histopathology revealed that the severity of thrombotic changes after AGN1 injection was minimal to slight, while changes after PMMA injection were minimal to massive. CONCLUSION Acute systemic effects of intravascular AGN1 appeared to be comparable to or less than that of intravascular PMMA. Furthermore, in this preliminary study, the severity and incidence of pulmonary histological changes were lower for AGN1 compared to PMMA

    eMouseAtlas, EMAGE, and the spatial dimension of the transcriptome

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    Abstract eMouseAtlas (www.emouseatlas.org) is a com-prehensive online resource to visualise mouse development and investigate gene expression in the mouse embryo. We have recently deployed a completely redesigned Mouse Anatomy Atlas website (www.emouseatlas.org/emap/ema) that allows users to view 3D embryo reconstructions, delineated anatomy, and high-resolution histological sec-tions. A new feature of the website is the IIP3D web tool that allows a user to view arbitrary sections of 3D embryo reconstructions using a web browser. This feature provides interactive access to very high-volume 3D images via a tiled pan-and-zoom style interface and circumvents the need to download large image files for visualisation. eMouseAtla
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