179 research outputs found

    Academic Management — The Case for Challenge

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    An examination was made of how well certain units involved in managing the teaching-learning organizations of universities work. Criteria for acceptable operation involved clarity of communication, matches between objectives at different levels of the administrative hierarchy, matches between objectives and methods, and rationality of approach to cost-effectiveness. Significant defects were found in relation to each of these criteria suggesting that both selection and training of staff at all levels are now, to some degree, deficient. Inefficiencies relating to poor information gathering, and poor communication were identified as was unnecessary duplication between faculty and department organizations.Nous avons examiné l'efficacité de divers organismes qui gÚrent les modalités de l'enseignement et des études au sein des universités. L'opération jugée acceptable devait répondre aux critÚres suivants: 1) clarté de la communication, 2) corres-pondance des objectifs à divers niveaux de la hiérarchie administrative, 3) corré-lation entre les objectifs et les méthodes, 4) rationalité envers les questions de coût et d'efficacité. Pour chacun de ces critÚres, nous avons découvert des dis-cordances importantes - ce qui semble indiquer une déficience actuelle dans la sélection et dans la formation du personnel, à tous les niveaux. Ces discordances résultent de la faiblesse des méthodes d'information, du manque de communica-tion, et du fait que, inutilement, les organismes a l'intérieur de la faculté font double emploi avec ceux des départements

    The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

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    A major trough ("Belgica Trough") eroded by a palaeo-ice stream crosses the continental shelf of the southern Bellingshausen Sea (West Antarctica) and is associated with a trough mouth fan ("Belgica TMF") on the adjacent continental slope. Previous marine geophysical and geological studies investigated the bathymetry and geomorphology of Belgica Trough and Belgica TMF, erosional and depositional processes associated with bedform formation, and the temporal and spatial changes in clay mineral provenance of subglacial and glaciomarine sediments. Here, we present multi-proxy data from sediment cores recovered from the shelf and uppermost slope in the southern Bellingshausen Sea and reconstruct the ice-sheet history since the last glacial maximum (LGM) in this poorly studied area of West Antarctica. We combined new data (physical properties, sedimentary structures, geochemical and grain-size data) with published data (shear strength, clay mineral assemblages) to refine a previous facies classification for the sediments. The multi-proxy approach allowed us to distinguish four main facies types and to assign them to the following depositional settings: 1) subglacial, 2) proximal grounding-line, 3) distal sub-ice shelf/sub-sea ice, and 4) seasonal open-marine. In the seasonal open-marine fades we found evidence for episodic current-induced winnowing of near-seabed sediments on the middle to outer shelf and at the uppermost slope during the late Holocene. In addition, we obtained data on excess Pb-210 activity at three core sites and 44 AMS C-14 dates from the acid-insoluble fraction of organic matter (AIO) and calcareous (micro-) fossils, respectively, at 12 sites. These chronological data enabled us to reconstruct, for the first time, the timing of the last advance and retreat of the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet (APIS) in the southern Bellingshausen Sea. We used the down-core variability in sediment provenance inferred from clay mineral changes to identify the most reliable AIO C-14 ages for ice-sheet retreat. The palaeo-ice stream advanced through Belgica Trough after similar to 36.0 corrected C-14 ka before present (B.P.). It retreated from the outer shelf at similar to 25.5 ka B.P, the middle shelf at similar to 19.8 ka B.P., the inner shelf in Eltanin Bay at similar to 12.3 ka B.P., and the inner shelf in Ronne Entrance at similar to 6.3 ka B.P. The retreat of the WAIS and APIS occurred slowly and stepwise, and may still be in progress. This dynamical ice-sheet behaviour has to be taken into account for the interpretation of recent and the prediction of future mass-balance changes in the study area. The glacial history of the southern Bellingshausen Sea is unique when compared to other regions in West Antarctica, but some open questions regarding its chronology need to be addressed by future work. (C) 2010 Elsevier Ltd. All rights reserved

    EB Ford revisited: assessing the long-term stability of wing-spot patterns and population genetic structure of the meadow brown butterfly on the Isles of Scilly

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Data files of wing spot sizes and AFLP genotypes available from the Dryad Digital Repository: http://dx.doi.org/10.5061/dryad.j7v42.Understanding selection in the wild remains a major aim of evolutionary ecology and work by Ford and colleagues on the meadow brown butterfly Maniola jurtina did much to ignite this agenda. A great deal of their work was conducted during the 1950s on the Isles of Scilly. They documented island-specific wing-spot patterns that remained consistent over about a decade, but patterns on some islands changed after environmental perturbation. It was suggested that these wing-spot patterns reflected island-specific selection and that there was little migration between islands. However, genetic studies to test the underlying assumption of restricted migration are lacking and it is also unknown whether the originally described wing-spot patterns have persisted over time. We therefore collected female butterflies from five of Ford's original study locations, including three large islands (St Mary's, St Martin's and Tresco) and two small islands (Tean and St Helen's). Wing-spot patterns had not changed appreciably over time on three of the islands (two large and one small), but were significantly different on the other two. Furthermore, analysis of 176 amplified fragment length polymorphisms revealed significant genome-wide differentiation among the five islands. Our findings are consistent with Ford's conclusions that despite the close proximity of these islands, there is restricted gene flow among them.Heredity advance online publication, 2 November 2016; doi:10.1038/hdy.2016.94.We thank the Genetics Society for a fieldwork grant (to DJH) that funded the collection trip and DJH thanks Mike Johnson for sparking interest in this area. SWB is supported by the Australian Research Council and a Ramsay Fellowship, NW by a Royal Society Wolfson Fellowship and NERC and DJH by the Leverhulme Trust

    A persistent Norwegian Atlantic Current through the Pleistocene glacials

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    Changes in ocean‐circulation regimes in the northern North Atlantic and the Nordic Seas may affect not only the Arctic but potentially hemispheric or even global climate. Therefore, unraveling the long‐term evolution of the North Atlantic Current‐Norwegian Atlantic Current system through the Pleistocene glaciations could yield useful information and climatological context for understanding contemporary changes. In this work, ~50,000 km2 of 3‐D seismic reflection data are used to investigate the Pleistocene stratigraphy for evidence of paleo‐oceanographic regimes on the mid‐Norwegian margin since 2.58 Ma. Across 33 semicontinuous regional paleo‐seafloor surfaces ~17,500 iceberg scours have been mapped. This mapping greatly expands our spatiotemporal understanding of currents and iceberg presence in the eastern Nordic Seas. The scours display a dominant southwest‐northeast trend that complements previous sedimentological and numerical modeling studies that suggest northward‐flowing currents in the Norwegian Sea during the Pleistocene. This paleo‐oceanographic study suggests that through many of the Pleistocene glaciations, the location of surface ocean currents in the Norwegian Sea and, by extension, the eastern North Atlantic, were broadly similar to the present

    Enhanced glacial discharge from the eastern Antarctic Peninsula since the 1700s associated with a positive Southern Annular Mode

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    Abstract: The Antarctic Peninsula Ice Sheet is currently experiencing sustained and accelerating loss of ice. Determining when these changes were initiated and identifying the main drivers is hampered by the short instrumental record (1992 to present). Here we present a 6,250 year record of glacial discharge based on the oxygen isotope composition of diatoms (ή18Odiatom) from a marine core located at the north-eastern tip of the Antarctic Peninsula. We find that glacial discharge - sourced primarily from ice shelf and iceberg melting along the eastern Antarctic Peninsula – remained largely stable between ~6,250 to 1,620 cal. yr BP, with a slight increase in variability until ~720 cal. yr. BP. An increasing trend in glacial discharge occurs after 550 cal. yr BP (A.D. 1400), reaching levels unprecedented during the past 6,250 years after 244 cal. yr BP (A.D. 1706). A marked acceleration in the rate of glacial discharge is also observed in the early part of twentieth century (after A.D. 1912). Enhanced glacial discharge, particularly after the 1700s is linked to a positive Southern Annular Mode (SAM). We argue that a positive SAM drove stronger westerly winds, atmospheric warming and surface ablation on the eastern Antarctic Peninsula whilst simultaneously entraining more warm water into the Weddell Gyre, potentially increasing melting on the undersides of ice shelves. A possible implication of our data is that ice shelves in this region have been thinning for at least ~300 years, potentially predisposing them to collapse under intensified anthropogenic warming

    Variability in ice motion and dynamic discharge from Devon Ice Cap, Nunavut, Canada

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    © The Author(s) 2017. Feature tracking of approximately annually separated Landsat-7 ETM+ imagery acquired from 1999 to 2010 and speckle tracking of 24-day separated RADARSAT-2 imagery acquired from 2009 to 2015 reveal that motion of the major tidewater glaciers of Devon Ice Cap is more variable than previously described. The flow of almost half (six of 14) of the outlet glaciers slowed over the observation period, while that of the terminus regions of three of 14 of the glaciers sped up in the most recent years of observation. The North Croker Bay Glacier of southern Devon Ice Cap showed the greatest variability in motion, oscillating between multi-year (three or more) periods of slower and faster flow and exhibited a pattern of velocity variability that is different from that of the rest of the ice cap's outlet glaciers. Comparisons between areas of dynamic variability and glacier bed topography indicate that velocity variability is largely restricted to regions where the glacier bed is grounded below sea level. Derived velocities are combined with measurements of ice thickness at the fronts of tidewater glacier to determine a mean annual (2009; 2011-15) dynamic ice discharge of 0.41 ± 0.11 Gt a-1 for Devon Ice Cap. The Belcher Glacier is becoming a larger source of mass loss via ice discharge.NERC (NE/K004999/1

    The Impact of HIV, an Antiretroviral Programme and Tuberculosis on Mortality in South African Platinum Miners, 1992–2010

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    HIV and tuberculosis (TB) are the most common causes of death in South Africa. Antiretroviral therapy (ART) programmes should have had an impact on mortality rates. This study describes the impact of HIV, a Wellness (HIV/ART) programme and TB on population-wide trends in mortality and causes of death among South African platinum miners, from before the HIV epidemic into the ART era

    Possible interactions between bacterial diversity, microbial activity and supraglacial hydrology of cryoconite holes in Svalbard

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    The diversity of highly active bacterial communities in cryoconite holes on three Arctic glaciers in Svalbard was investigated using terminal restriction fragment length polymorphism (T-RFLP) of the 16S rRNA locus. Construction and sequencing of clone libraries allowed several members of these communities to be identified, with Proteobacteria being the dominant one, followed by Cyanobacteria and Bacteroidetes. T-RFLP data revealed significantly different communities in holes on the (cold) valley glacier Austre BrĂžggerbreen relative to two adjacent (polythermal) valley glaciers, Midtre LovĂ©nbreen and Vestre BrĂžggerbreen. These population compositions correlate with differences in organic matter content, temperature and the metabolic activity of microbial communities concerned. No within-glacier spatial patterns were observed in the communities identified over the 2-year period and with the 1 km-spaced sampling. We infer that surface hydrology is an important factor in the development of cryoconite bacterial communities
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