684 research outputs found

    Designing a flexible support system in dialogue with students to meet their needs

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    A more stringent financial climate, alongside technological and lifestyle changes, have diversified student needs and promoted the use of inclusive learning and support strategies. This paper reports on the development and evaluation of academic skills centres at an English Higher Education Institution and considers ways in which the service is able to benefit users and providers, it goes on to argue that, by fostering a dialogue with students and using a range of delivery models, the provision has been made flexible, diversified and student centred and thereby addresses issues of current significance within the institution and sector more broadly

    From white elephant to Nobel Prize: Dennis Gabor’s wavefront reconstruction

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    Dennis Gabor devised a new concept for optical imaging in 1947 that went by a variety of names over the following decade: holoscopy, wavefront reconstruction, interference microscopy, diffraction microscopy and Gaboroscopy. A well-connected and creative research engineer, Gabor worked actively to publicize and exploit his concept, but the scheme failed to capture the interest of many researchers. Gabor’s theory was repeatedly deemed unintuitive and baffling; the technique was appraised by his contemporaries to be of dubious practicality and, at best, constrained to a narrow branch of science. By the late 1950s, Gabor’s subject had been assessed by its handful of practitioners to be a white elephant. Nevertheless, the concept was later rehabilitated by the research of Emmett Leith and Juris Upatnieks at the University of Michigan, and Yury Denisyuk at the Vavilov Institute in Leningrad. What had been judged a failure was recast as a success: evaluations of Gabor’s work were transformed during the 1960s, when it was represented as the foundation on which to construct the new and distinctly different subject of holography, a re-evaluation that gained the Nobel Prize for Physics for Gabor alone in 1971. This paper focuses on the difficulties experienced in constructing a meaningful subject, a practical application and a viable technical community from Gabor’s ideas during the decade 1947-1957

    Age, correlation, and provenance of the neoproterozoic skelton group, Antarctica: grenville age detritus on the margin of east Antarctica

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    Detrital zircon U‐Pb ages constrain the age and provenance of the Skelton Group in southern Victoria Land, one of several Proterozoic‐Cambrian metasedimentary units that form basement to the Ross Orogen in East Antarctica. The age of the youngest detrital zircons combined with previous dating of crosscutting intrusive rocks indicates deposition of the northern and southern parts of the Skelton Group between ca. 1050–535 and ca. 950–551 Ma, respectively. Many zircons in the northern part of the Skelton Group crystallized after partial melting during upper amphibolite facies metamorphism at ca. 505–480 Ma, although older ca. 550‐Ma metamorphic zircon rims indicate an earlier episode of high‐grade metamorphism. Detrital zircon ages from the Skelton Group are dominated by ca. 1300–950‐Ma ages similar to those in the Beardmore Group in East Antarctica and the Adelaidean succession of South Australia, suggesting that these rocks are generally correlative. Zircons that crystallized at ca. 1050 Ma form the major age population of the northern Skelton Group, while a broader range of Neoproterozoic zircons form significant components in other sediments deposited on the margin of East Antarctica–Australia at this time, indicating a close proximity to exposed Grenville age crust. Inferred basement rocks of Grenville age beneath the Ross Orogen in East Antarctica (represented by a potential 1049 ± 11‐Ma orthogneiss), Paleozoic cover in eastern Australia, and ice in Marie Byrd Land in West Antarctica are potential sources for the Grenville age component in these Neoproterozoic sedimentary rocks

    Mass transfer in the lower crust: Evidence for incipient melt assisted flow along grain boundaries in the deep arc granulites of Fiordland, New Zealand

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    Knowledge of mass transfer is critical in improving our understanding of crustal evolution, however mass transfer mechanisms are debated, especially in arc environments. The Pembroke Granulite is a gabbroic gneiss, passively exhumed from depths of >45 km from the arc root of Fiordland, New Zealand. Here, enstatite and diopside grains are replaced by coronas of pargasite and quartz, which may be asymmetric, recording hydration of the gabbroic gneiss. The coronas contain microstructures indicative of the former presence of melt, supported by pseudosection modeling consistent with the reaction having occurred near the solidus of the rock (630–710°C, 8.8–12.4 kbar). Homogeneous mineral chemistry in reaction products indicates an open system, despite limited metasomatism at the hand sample scale. We propose the partial replacement microstructures are a result of a reaction involving an externally derived hydrous, silicate melt and the relatively anhydrous, high-grade assemblage. Trace element mapping reveals a correlation between reaction microstructure development and bands of high-Sr plagioclase, recording pathways of the reactant melt along grain boundaries. Replacement microstructures record pathways of diffuse porous melt flow at a kilometer scale within the lower crust, which was assisted by small proportions of incipient melt providing a permeable network. This work recognizes melt flux through the lower crust in the absence of significant metasomatism, which may be more common than is currently recognized. As similar microstructures are found elsewhere within the exposed Fiordland lower crustal arc rocks, mass transfer of melt by diffuse porous flow may have fluxed an area >10,000 km2

    Evaluating the importance of metamorphism in the foundering of continental crust

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    The metamorphic conditions and mechanisms required to induce foundering in deep arc crust are assessed using an example of representative lower crust in SW New Zealand. Composite plutons of Cretaceous monzodiorite and gabbro were emplaced at ~1.2 and 1.8 GPa are parts of the Western Fiordland Orthogneiss (WFO); examples of the plutons are tectonically juxtaposed along a structure that excised ~25 km of crust. The 1.8 GPa Breaksea Orthogneiss includes suitably dense minor components (e.g. eclogite) capable of foundering at peak conditions. As the eclogite facies boundary has a positive dP/dT, cooling from supra-solidus conditions (T > 950 ºC) at high-P should be accompanied by omphacite and garnet growth. However, a high monzodioritic proportion and inefficient metamorphism in the Breaksea Orthogneiss resulted in its positive buoyancy and preservation. Metamorphic inefficiency and compositional relationships in the 1.2 GPa Malaspina Pluton meant it was never likely to have developed densities sufficiently high to founder. These relationships suggest that the deep arc crust must have primarily involved significant igneous accumulation of garnet–clinopyroxene (in proportions >75%). Crustal dismemberment with or without the development of extensional shear zones is proposed to have induced foundering of excised cumulate material at P > 1.2 GPa

    Palaeotectonic setting of the south-eastern Kédougou-Kéniéba Inlier, West Africa: new insights from igneous trace element geochemistry and U-Pb zircon ages

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    New U-Pb zircon ages and geochemistry from the eastern Kédougou-Kéniéba Inlier are presented and integrated with published data to generate a revised tectonic framework for the westernmost Birimian terranes. The Falémé Volcanic Belt and Kofi Series are highly prospective, hosting several multi-million ounce gold deposits and a significant iron ore resource, but remain under-researched. It is therefore important to constrain the fundamental geological setting. The igneous rocks of the eastern Kédougou-Kéniéba Inlier are dominantly of high-K calc-alkaline affinity, with fractionated REE patterns and negative Nb-Ta anomalies. The plutonic rocks in the Falémé Belt are dioritic to granodioritic in composition, with moderately fractionated REE patterns and metaluminous A/CNK signatures. Felsic, peraluminous granite stocks, dykes and plutons with fractionated REE patterns and negative Eu, Ti and P anomalies intruded both the Falémé Belt and Kofi Series. Albitisation masks the affinity of some units, although use of the Th-Co diagram shows that prior to albitisation, all igneous units belonged to the high-K calc-alkaline series. New U-Pb age data for the Boboti and Balangouma plutons indicate crystallisation at 2088.5 ± 8.5 Ma and at 2112 ± 13 Ma, respectively. Inherited zircons in the Boboti pluton indicate magmatic activity in the Falémé Belt at 2218 ± 83 Ma coincided with the oldest dated units in the Mako Belt to the West. Systematic changes in Dy/Yb, Sm/La, Nb/Zr, Rb concentration, Eu-anomaly and ɛNdt over ∼200 Ma reveal that the tectonic setting in the KKI evolved from a volcanic island arc environment to an active continental margin. Crustal thickening, as a result of a shift to collisional tectonic setting, combined with magmatic differentiation, led to the generation of peraluminous, granitic melts with a significant crustal component. A small suite of more basic intrusive and extrusive rocks on the eastern margin of the Dialé-Daléma basin are highly metaluminous and display limited LILE enrichment, with normalised HREE values close to unity. The Daléma igneous rocks may have formed in an extensional back arc, related to the arc system

    Laparoscopic management of early primary peritoneal pregnancy: a case report

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    Peritoneal pregnancy is an implantation in the peritoneal cavity exclusive of tubal, ovarian, or intra-ligamentary implantations. This is a rare obstetric complication with high maternal mortality and even higher perinatal mortality, and secondary type was most common. Risk factors for peritoneal pregnancy are previous history of extrauterine pregnancy or tubal surgery pelvic post-inflammatory status or presence of an intra-uterine device. As it is a life-threatening condition, expectant management carries a risk of sudden life-threatening intra-abdominal bleeding and a generally poor fetal prognosis. So, when it is recognized, immediate termination of pregnancy is usually recommended. Early diagnosis of peritoneal pregnancy is difficult, but is important by their life threatening progress course to patients. Recently, we experienced primary peritoneal pregnancy which meets both the original and modified criteria. In this paper, we reported the case of early diagnosed and successfully treated peritoneal pregnancy despite of their diagnosis was incidentally

    Letter from S. Austin Allibone, Philadelphia, Pennsylvania, to James William Kimball, Boston, Massachusetts : autograph manuscript signed, 1868 October 6

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    The letter is about religious tracts.https://repository.wellesley.edu/autographletters/1032/thumbnail.jp

    Effect of early tranexamic acid administration on mortality, hysterectomy, and other morbidities in women with post-partum haemorrhage (WOMAN): an international, randomised, double-blind, placebo-controlled trial

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    Background Post-partum haemorrhage is the leading cause of maternal death worldwide. Early administration of tranexamic acid reduces deaths due to bleeding in trauma patients. We aimed to assess the effects of early administration of tranexamic acid on death, hysterectomy, and other relevant outcomes in women with post-partum haemorrhage. Methods In this randomised, double-blind, placebo-controlled trial, we recruited women aged 16 years and older with a clinical diagnosis of post-partum haemorrhage after a vaginal birth or caesarean section from 193 hospitals in 21 countries. We randomly assigned women to receive either 1 g intravenous tranexamic acid or matching placebo in addition to usual care. If bleeding continued after 30 min, or stopped and restarted within 24 h of the first dose, a second dose of 1 g of tranexamic acid or placebo could be given. Patients were assigned by selection of a numbered treatment pack from a box containing eight numbered packs that were identical apart from the pack number. Participants, care givers, and those assessing outcomes were masked to allocation. We originally planned to enrol 15 000 women with a composite primary endpoint of death from all-causes or hysterectomy within 42 days of giving birth. However, during the trial it became apparent that the decision to conduct a hysterectomy was often made at the same time as randomisation. Although tranexamic acid could influence the risk of death in these cases, it could not affect the risk of hysterectomy. We therefore increased the sample size from 15 000 to 20 000 women in order to estimate the effect of tranexamic acid on the risk of death from post-partum haemorrhage. All analyses were done on an intention-to-treat basis. This trial is registered with ISRCTN76912190 (Dec 8, 2008); ClinicalTrials.gov, number NCT00872469; and PACTR201007000192283. Findings Between March, 2010, and April, 2016, 20 060 women were enrolled and randomly assigned to receive tranexamic acid (n=10 051) or placebo (n=10 009), of whom 10 036 and 9985, respectively, were included in the analysis. Death due to bleeding was significantly reduced in women given tranexamic acid (155 [1·5%] of 10 036 patients vs 191 [1·9%] of 9985 in the placebo group, risk ratio [RR] 0·81, 95% CI 0·65–1·00; p=0·045), especially in women given treatment within 3 h of giving birth (89 [1·2%] in the tranexamic acid group vs 127 [1·7%] in the placebo group, RR 0·69, 95% CI 0·52–0·91; p=0·008). All other causes of death did not differ significantly by group. Hysterectomy was not reduced with tranexamic acid (358 [3·6%] patients in the tranexamic acid group vs 351 [3·5%] in the placebo group, RR 1·02, 95% CI 0·88–1·07; p=0·84). The composite primary endpoint of death from all causes or hysterectomy was not reduced with tranexamic acid (534 [5·3%] deaths or hysterectomies in the tranexamic acid group vs 546 [5·5%] in the placebo group, RR 0·97, 95% CI 0·87-1·09; p=0·65). Adverse events (including thromboembolic events) did not differ significantly in the tranexamic acid versus placebo group. Interpretation Tranexamic acid reduces death due to bleeding in women with post-partum haemorrhage with no adverse effects. When used as a treatment for postpartum haemorrhage, tranexamic acid should be given as soon as possible after bleeding onset. Funding London School of Hygiene & Tropical Medicine, Pfizer, UK Department of Health, Wellcome Trust, and Bill & Melinda Gates Foundation
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