4,320 research outputs found

    Sequence of Quaternary Sediments in the Bélanger Sand Pit, Pointe-Fortune, Québec-Ontario

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    Drilling in the floor of the Bélanger sand pit (Ontario) near Pointe-Fortune, Québec, added 3 stratigraphic units to those already exposed in the pit: a lowermost till, and an intermediate organic-bearing (?) sand-clay unit overlain by a massive lacustrine clay. The subsurface units, comprising about 70% of the stratigraphy, complete the Quaternary sequence exposed in the pit face : an organic-bearing silty sand (>40 000 years BP) unit truncated by an unfos-siliferous sand unit and overlain by the uppermost till. The overall sequence forms a continuous 18 m column of Quaternary sediments. The Pointe-Fortune sequence shows some similarities with the Trois-Rivières Quaternary series which includes the Saint-Pierre sediments >75 000 years old. In addition to stratigraphie information the combination of direct (drilling) and indirect (geophysical) methods of investigation by providing a three-dimensional picture of the subsurface has proved helpful in interpreting the stratigraphy. The geotechnical properties of a massive overconsolidated clay have been determined to facilitate the planning of future subsurface investigation.Des forages à l'intérieur de la sablière Bélanger (Ontario) près de Pointe-Fortune, Québec, permettent d'ajouter trois unités stratigraphiques à celles déjà visibles à la surface: un till inférieur, et, en position intermédiaire, un ensemble sable-argile avec matière organique(?) recouvert par une argile lacustre. Ces trois unités comprennent près de 70% de la stratigraphie du site et sont recouvertes par une unité de sable et de sable silteux contenant de la matière organique datée à >40 000 ans. Cette dernière est tronquée par une unité de sable non fossilifère, et un till occupe le haut de la coupe. La totalité des sédiments quaternaires forment une séquence de 18 m de haut. La séquence quaternaire de Pointe-Fortune présente des similarités avec la série quaternaire de Trois-Rivières, qui inclut les sédiments de Saint-Pierre d'un âge de plus de 75 000 ans. Cette étude en plus de fournir de nouvelles données sur la stratigraphie démontre que l'utilisation conjointe de techniques directes (forages) et indirectes (géophysiques) s'avère utile à l'interprétation des données stratigraphiques en présentant une image tri-dimensionnelle du terrain. Afin de faciliter de futurs travaux de forage, nous avons établi les propriétés géotechniques de l'argile massive compacte

    The cAMP-producing agonist beraprost inhibits human vascular smooth muscle cell migration via exchange protein directly activated by cAMP

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    This work was supported by the British Heart foundation (grant FS/11/23/28730). J.S.M. was funded by a British Heart Foundation PhD studentship. Funding to pay the Open Access publication charges for this article was provided by the Charities Open Access Fund (UK).Peer reviewedPublisher PD

    Recent advances in understanding the structural and functional evolution of FtsH proteases

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    The FtsH family of proteases are membrane-anchored, ATP-dependent, zinc metalloproteases. They are universally present in prokaryotes and the mitochondria and chloroplasts of eukaryotic cells. Most bacteria bear a single ftsH gene that produces hexameric homocomplexes with diverse house-keeping roles. However, in mitochondria, chloroplasts and cyanobacteria, multiple FtsH homologues form homo and heterocomplexes with specialised functions in maintaining photosynthesis and respiration. The diversification of FtsH homologues combined with selective pairing of FtsH isomers is a versatile strategy to enable functional adaptation. In this article we summarise recent progress in understanding the evolution, structure and function of FtsH proteases with a focus on the role of FtsH in photosynthesis and respiration

    Advanced Low-Cost O2/H2 Engines for the SSTO Application

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    The recent NASA Access to Space study examined future Earth to orbit (ETO) transportation needs and fleets out to 2030. The baseline in the option 3 assessment was a single stage to orbit (SSTO) vehicle. A study was conducted to assess the use of new advanced low cost O2/H2 engines for this SSTO application. The study defined baseline configurations and ground rules and defined six engine cycles to explore engine performance. The cycles included an open cycle, and a series of closed cycles with varying abilities to extract energy from the propellants to power he turbomachinery. The cycles thus varied in the maximum chamber pressure they could reach and in their weights at any given chamber pressure. The weight of each cycle was calculated for two technology levels versus chamber pressure up to the power limit of the cycle. The performance in the SSTO mission was then modeled using the resulting engine weights and specific impulse performance using the Access to Space option 3 vehicle. The results showed that new O2/H2 engines are viable and competitive candidates for the SSTO application using chamber pressures of 4,000 psi

    Smartphone screening for neonatal jaundice via ambient-subtracted sclera chromaticity

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    Jaundice is a major cause of mortality and morbidity in the newborn. Globally, early identification and home monitoring are significant challenges in reducing the incidence of jaundice-related neurological damage. Smartphone cameras are promising as colour-based screening tools as they are low-cost, objective and ubiquitous. We propose a novel smartphone method to screen for neonatal jaundice by imaging the sclera. It does not rely on colour calibration cards or accessories, which may facilitate its adoption at scale and in less economically developed regions. Our approach is to explicitly address three confounding factors in relating colour to jaundice: (1) skin pigmentation, (2) ambient light, and (3) camera spectral response. (1) The variation in skin pigmentation is avoided by imaging the sclera. (2) With the smartphone screen acting as an illuminating flash, a flash/ no-flash image pair is captured using the front-facing camera. The contribution of ambient light is subtracted. (3) In principle, this permits a device- and ambient-independent measure of sclera chromaticity following a one-time calibration. We introduce the concept of Scleral-Conjunctival Bilirubin (SCB), in analogy with Transcutaneous Bilirubin (TcB). The scleral chromaticity is mapped to an SCB value. A pilot study was conducted in the UCL Hospital Neonatal Care Unit (n = 37). Neonates were imaged using a specially developed app concurrently with having a blood test for total serum bilirubin (TSB). The better of two models for SCB based on ambient-subtracted sclera chromaticity achieved r = 0.75 (p250μmol/L (area under receiver operating characteristic curve, AUROC, 0.86), and 92% (specificity 67%) in identifying newborns with TSB>205μmol/L (AUROC 0.85). These results are comparable to modern transcutaneous bilirubinometers

    Temporal Variations of Titan's Middle-Atmospheric Temperatures From 2004-2009 Observed by Cassini/CIRS

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    We use five and one-half years of limb- and nadir-viewing temperature mapping observations by the Composite Infrared Radiometer-Spectrometer (CIRS) on the Cassini Saturn orbiter, taken between July 2004 and December 2009 (Ls from 293deg to 4deg; northern mid-winter to just after northern spring equinox), to monitor temperature changes in the upper stratosphere and lower mesosphere of Titan. The largest changes are in the northern (winter) polar stratopause, which has declined in temperature by over 20 K between 2005 and 2009. Throughout the rest of the mid to upper stratosphere and lower mesosphere, temperature changes are less than 5 K. In the southern hemisphere, temperatures in the middle stratosphere near 1 mbar increased by 1 to 2K from 2004 through early 2007, then declined by 2 to 4K throughout 2008 and 2009, with the changes, being larger at more, polar latitudes. Middle stratospheric temperatures at mid-northern latitudes show a small 1 to 2K increase, from 2005 through 2009. At north polar latitudes within the polar vortex, temperatures in the middle stratosphe=re show a approx. 4 K increase during 2007, followed by a comparable decrease in temperatures in 2008 and into early 2009. The observed temperature. changes in the north polar region are consistent with a weakening of the subsidence within the descending branch of the middle atmosphere meridional circulation
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