406 research outputs found
Micro-to-macro: astrodynamics at extremes of lengths-scale
This paper investigates astrodynamics at extremes of length-scale, ranging from swarms of future `smart dust' devices to the capture and utilisation of small near Earth asteroids. At the smallest length-scales families of orbits are found which balance the energy gain from solar radiation pressure with energy dissipation due to air drag. This results in long orbit lifetimes for high area-to-mass ratio `smart dust' devices. High area-to-mass hybrid spacecraft, using both solar sail and electric propulsion, are then considered to enable `pole-sitter' orbits providing a polar-stationary vantage point for Earth observation. These spacecraft are also considered to enable displaced geostationary orbits. Finally, the potential material resource available from captured near Earth asteroids is considered which can underpin future large-scale space engineering ventures. The use of such material for geo-engineering is investigated using a cloud of unprocessed dust in the vicinity of the Earth-Sun point to fractionally reduce solar insolation
Hulton Abbey Skeletal Digitisation Project JISC / Academy Distributed e-Learning (DeL) Programme II
The aim of this project was to produce a digitised record/resources from skeletal material recovered from a well publicised excavation of historical importance in Stoke-on-Trent, Staffordshire. This excavation took place at Hulton Abbey and produced a published book as part of its work. Whilst the initial aim of this project was to produce digitised resources which will be actively used for forensic science teaching at Staffordshire University and Reading University these can equally and readily be adopted by other organisations and institutions. In addition, due to the interdisciplinary interest in this work, the potential for re-purposing and re-use of these digitised resources is enormous. Due to the anatomical nature of the skeletal excavations there is potential for use in anthropological and biological (e.g. disease) studies and there is also historical and religious sociological and cultural applications as well as in photographic studies, computing and e-learning technologies
Líquenes corticícolas en el caribe colombiano
Se documentó la composición de la flora liquénica corticícola de cinco localidades de la región Caribe colombiana, tres de tierras bajas (planicies) y dos de tierras altas (macizos montañosos). Se encontraron 348 morfoespecies de líquenes corticícolas, basadas en 950 ejemplares, de las cuales 215 se determinaron a nivel de especie y 62 a género (debido a la ausencia de estructuras reproductivas o a la carencia de trabajos taxonómicos). El resto de las especies (71) constituyó un grupo líquenes costrosos estériles que carecen de caracteres específicos para su identificación. Se encontraron 115 registros nuevos para Colombia, la mayoría de especies son registros nuevos para las áreas de estudio. El número total de especies para la región Caribe, incluyendo los estudios previos de macrolíquenes y líquenes foliícolas, se estimó en aproximadamente 400
Are Subjects Making Financial Decisions in Lab Auctions or Are They Just Gambling?
Optimal bidding strategies in first-price and Dutch auctions are theoretically isomorphic but depend on bidder risk attitudes. However, laboratory experiments consistently find different behaviour between auction formats. This article explores whether the notion in psychology that financial and gambling risks are viewed differently can explain the discrepancy. Ultimately, the evidence does not support this hypothesis, but a bidder\u27s propensity to gamble is associated with how much risk he takes in both auctions whereas his propensity to take financial risks is not. The results suggest that subjects may view themselves as gambling in laboratory auctions rather than making financial decisions
Angiography-derived index of microcirculatory resistance as a novel, pressure-wire-free tool to assess coronary microcirculation in ST elevation myocardial infarction
Immediate assessment of coronary microcirculation during treatment of ST elevation myocardial infarction (STEMI) may facilitate patient stratification for targeted treatment algorithms. Use of pressure-wire to measure the index of microcirculatory resistance (IMR) is possible but has inevitable practical restrictions. We aimed to develop and validate angiography-derived index of microcirculatory resistance (IMRangio) as a novel and pressure-wire-free index to facilitate assessment of the coronary microcirculation. 45 STEMI patients treated with primary percutaneous coronary intervention (pPCI) were enrolled. Immediately before stenting and at completion of pPCI, IMR was measured within the infarct related artery (IRA). At the same time points, 2 angiographic views were acquired during hyperaemia to measure quantitative flow ratio (QFR) from which IMRangio was derived. In a subset of 15 patients both IMR and IMRangio were also measured in the non-IRA. Patients underwent cardiovascular magnetic resonance imaging (CMR) at 48 h for assessment of microvascular obstruction (MVO). IMRangio and IMR were significantly correlated (rho: 0.85, p < 0.001). Both IMR and IMRangio were higher in the IRA rather than in the non-IRA (p = 0.01 and p = 0.006, respectively) and were higher in patients with evidence of clinically significant MVO (> 1.55% of left ventricular mass) (p = 0.03 and p = 0.005, respectively). Post-pPCI IMRangio presented and area under the curve (AUC) of 0.96 (CI95% 0.92-1.00, p < 0.001) for prediction of post-pPCI IMR > 40U and of 0.81 (CI95% 0.65-0.97, p < 0.001) for MVO > 1.55%. IMRangio is a promising tool for the assessment of coronary microcirculation. Assessment of IMR without the use of a pressure-wire may enable more rapid, convenient and cost-effective assessment of coronary microvascular function
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Fungi evolved right on track
Dating of fungal divergences with molecular clocks thus far has yielded highly inconsistent results. The origin of fungi was estimated at between 660 million and up to 2.15 billion y ago, and the divergence of the two major lineages of higher fungi, Ascomycota and Basidiomycota, at between 390 million y and up to 1.5 billion y ago. Assuming that these inconsistencies stem from various causes, we reassessed the systematic placement of the most important fungal fossil, Paleopyrenomycites, and recalibrated internally unconstrained, published molecular clock trees by applying uniform calibration points. As a result the origin of fungi was re-estimated at between 760 million and 1.06 billion y ago and the origin of the Ascomycota at 500–650 million y ago. These dates are much more consistent than previous estimates, even if based on the same phylogenies and molecular clock trees, and they are also much better in line with the fossil record of fungi and plants and the ecological interdependence between filamentous fungi and land plants. Our results do not provide evidence to suggest the existence of ancient protolichens as an alternative to explain the ecology of early terrestrial fungi in the absence of land plants.Organismic and Evolutionary Biolog
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