148 research outputs found
sj-docx-1-ejo-10.1177_11206721231154611 - Supplemental material for Stress and cataract surgery: A nationwide study evaluating surgeon burnout
No full textSupplemental material, sj-docx-1-ejo-10.1177_11206721231154611 for Stress and cataract surgery: A nationwide study evaluating surgeon burnout by Abdus Samad Ansari, Annie See Wah Tung, David M Wright, Patrick Watts and Gwyn Samuel Williams in European Journal of Ophthalmology</p
Magneto hall effect on unsteady elastico-viscous nanofluid slip flow in a channel in presence of thermal radiation and heat generation with Brownian motion
No full textPoverty Research Rethought
Get PDFKapittel 1 i boken: "Poverty: a global review. Handbook on international poverty research
Effect of surface oxidation on thermomechanical behavior of NiTi shape memory alloy wire
No full textSedimentation in the Ritland Impact Structure, western Norway
No full textThe Ritland structure is the remnants of a 2.7 km diameter, 350 m deep, Early to Middle Cambrian marine impact crater, located in Hjelmeland, western Norway. The impact origin of this structure was proposed in 2001 based on geological mapping. In 2007, further investigation confirmed the presence of rocks of melt origin and the subsequent shock-metamorphic features. Detailed field mapping and sedimentological and mineralogical analyses of the crater infill, explaining the possible depositional mechanisms, sedimentary environments and provenance, were the main objectives of this study. The Ritland crater infill studies were further extended into a comparative analysis with some selected marine crater infills, aiming to achieve a better understanding of the post-impact depositional mechanisms and sedimentary environments.
The Ritland crater was excavated in the gneissic sub-Cambrian peneplain by a bolide impact of ~115 m diameter. Recent studies on the lower Palaeozoic sediments outside the crater and intercalated ejecta beds indicate that the Ritland target site probably had experienced the Early Cambrian marine transgression when the bolide impacted, possibly into shoreface-close environments in the inner shelf. The Ritland crater infills were broadly classified into three sedimentation stages: A) late syn-impact, B) early post-impact, and C) late post-impact. Late syn-impact crater sedimentation represents an early stage of crater modification, where sediments were derived from collapse of the transient cavity and eventually avalanched down towards the crater centre. In the Ritland crater, extremely clast-rich breccias accompanied with the occasional appearance of reworked particles of melt origin, suggested to be deposited from rock avalanches, probably were deposited within seconds after impact. The rock avalanche deposits were overlain by debris flow deposits representing a water-wet condition related to the resurge of the seawater, thus deposited in the early post-impact stage. A pronounced shift from clast-supported to matrix-supported texture occurred in the upper part of these debris flow deposits. This transition probably reflects flow transformations, where debris flows were transformed into hyperconcentrated density flows during downslope transport, caused by dilution with the gradual ingress of sea water (seeping/breaching through the crater rim). The crater cavity soon (probably hours/days) filled with water and turbidity flows started to dominate. The sandstone succession exposed in the Ritland crater was deposited from turbidity currents, possibly representing minor submarine fans. The coarser clastics were deposited along the unstable, steep crater walls (derived from continued local erosion and slope-failure), while fine-grained sediments were deposited to the crater centre. The clast and matrix mineralogy of the late syn-impact and early post-impact crater-infilling sediments are comparable and dominated by local basement lithologies (target site) suggesting that these sediments were mostly derived from impact-generated debris.
The late-post impact succession in the Ritland crater is mostly fine-grained, e.g. sandstones, silty shale and shales deposited during later stages in comparatively stable crater conditions. The base of the late post-impact succession is marked by ~6 m of fine- to medium-grained sandstones and alternating fine-grained sandstones and silty shales. A marked increase in the textural maturity (increase in quartz/feldspar ratio), and an evidence of Cambrian marine life within these sandstones (unlike to early post-impact sandstones) suggest a transition from early post impact to late post-impact stage. These successions gradually shift upwards into dark grey to black shales with an about 180 m thick unit in the crater centre. The late post-impact sedimentation in the Ritland crater is suspension dominated with only minor episodes of turbidity current deposition observed in the transitional sandstones. Localised occurrences of coarser clastics within the marine shales along the steep crater wall suggest that gravity slides and screes were sporadically active along the crater wall for a long time after the impact, until the crater was eventually topped by marine clays.
Comparative analysis of the Ritland crater infill to the Gardnos, Kärdla, Lockne and Chesapeake Bay crater-filling deposits revealed almost a common order of occurrence of different sedimentary processes dominating at the different stages of crater sedimentation. The thickness and compositional variations are explained by differences in crater size, target lithology and water depth.
Rock avalanches dominated during the late syn-impact stage in the Ritland and Gardnos craters, mainly due to their crystalline target sites covered with only a thin veneer of marine sediments. Bolide impact into target sites with thick sedimentary cover will most likely generate large-scale collapses of the transient cavity and water-saturated rim layers, resulting in repetitive events of rock avalanches, slumping and gravity-slides as observed in the Kärdla and Chesapeake Bay craters. Impact in deeper water target sites, e.g. Lockne, does not show any clear-cut large-scale gravity-collapse but rather represents an early resurge.
Impact into crystalline target sites with a thin cover of shallow marine sediments in the Ritland and Gardnos craters resulted in well developed and elevated rim formation. The crater rim walls probably acted as a barrier and hindered the large-scale resurge-generated debris flow events within the craters in their early post-impact stage. Impact into thicker sedimentary cover at the target sites resulted in relatively weaker rim formation in the Kärdla and brim development in the Lockne and Chesapeake Bay craters, allowing multiple events of large-scale debris flows.
Turbidites were commonly observed at the waning stage of the resurge during early post-impact to the late post-impact stage. The Kärdla and Lockne craters represent thick resurge/back-surge turbidites. Ritland and Gardnos turbidites may have partially derived from back-surge but dominantly, most likely, form later slope-failure, erosion and reworking of the impact-derived debris. The turbidites in the Chesapeake Bay crater may either have been derived from the back-surge or from later slope-failure. Suspension deposition dominates in all the compared craters at the late stages when the crater cavities reached a more stable condition
Effects of ion-slip current on MHD free convection flow in a temperature stratified porous medium in a rotating system
No full textM<sub>2</sub>X Monolayers as Anode Materials for Li Ion Batteries
No full textElectrochemically efficient electrode materials are required for clean energy storage in Li ion batteries. We predict two-dimensional hexagonal metal nitrides, borides, and phosphides (Sc2B, Sc2N, Y2B, Y2N, and Y2P) and evaluate the feasibility of experimental realization. The materials combine excellent metallicity, as required for electrodes, with Li binding energies providing high storage capacity and a low
average open-circuit voltage. In contrast to two-dimensional silicene, borophene, and SnS2, we observe negligible structural distortions during Li adsorption and extraction, which results in high reversibility and a long cycle life. Superionic Li diffusion enables fast charge or discharge of next-generation Li ion batteries.The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST)
Current status and challenges for globalisation of veterinary medical education for the ‘One Health’ programme
No full textNewtonian and Non-Newtonian Pulsatile Flows through an Artery with Stenosis
Get PDFThe current study presents three-dimensional modeling and analysis of blood flow through artery stenosis under several variants of pulsatile flow to mimic the atherosclerosis artery disease. The study considered Newtonian and non-Newtonian blood flow models and solved the three-dimensional laminar and unsteady Navier-Stokes (NS) equations for different inlet velocity profiles. The Carreau Yasuda model was used for hemodynamics modeling of fluid viscosity. A comparative analysis was carried out for Newtonian and non-Newtonian fluid models under several simple pulsatile, equivalent pulsatile and physiological velocity profiles. The non-Newtonian fluid exhibited a higher centerline velocity. Wall shear stresses, shear strain rates, velocity fields, and vortex distribution for Newtonian and non-Newtonian fluid flows show significant differences. A higher wall shear was noticed near the stenosis. The vortex formed near the stenosis shifts to upstream and downstream of the stenosis with the change of velocity pulse. The velocity profile deflates more for non-Newtonian flows than the Newtonian flows
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