1000 resultados para RED PELAGICA


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We present the discovery of a red supergiant star that exploded as supernova 2003gd in the nearby spiral galaxy M74. The Hubble Space Telescope (HST) and the Gemini Telescope imaged this galaxy 6 to 9 months before the supernova explosion, and subsequent HST images confirm the positional coincidence of the supernova with a single resolved star that is a red supergiant of 8+4-2 solar masses. This confirms both stellar evolution models and supernova theories predicting that cool red supergiants are the immediate progenitor stars of type II-plateau supernovae.

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No abstract.

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There is a great need to design functional bioactive substitute materials capable of surviving harsh and diverse conditions within the human body. Calcium-phosphate ceramics, in particular hydroxyapatite are well established substitute materials for orthopaedic and dental applications. The aim of this study was to develop a bioceramic from alga origins suitable for bone tissue application. This was achieved by a novel synthesis technique using ambient pressure at a low temperature of 100 degrees C in a highly alkaline environment. The algae was characterised using SEM, BET, XRD and Raman Spectroscopy to determine its physiochemical properties at each stage. The results confirmed the successful conversion of mineralised red alga to hydroxyapatite, by way of this low-pressure hydrothermal process. Furthermore, the synthesised hydroxyapatite maintained the unique micro-porous structure of the original algae, which is considered beneficial in bone repair applications. (C) 2007 Elsevier B.V. All rights reserved.

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A World Conservation Union (IUCN) regional red list is an objective assessment of regional extinction risk and is not the same as a list of conservation priority species. Recent research reveals the widespread, but incorrect, assumption that IUCN Red List categories represent a hierarchical list of priorities for conservation action. We developed a simple eight-step priority-setting process and applied it to the conservation of bees in Ireland. Our model is based on the national red list but also considers the global significance of the national population; the conservation status at global, continental, and regional levels; key biological, economic, and societal factors; and is compatible with existing conservation agreements and legislation. Throughout Ireland, almost one-third of the bee fauna is threatened (30 of 100 species), but our methodology resulted in a reduced list of only 17 priority species. We did not use the priority species list to broadly categorize species to the conservation action required; instead, we indicated the individual action required for all threatened, near-threatened, and data-deficient species on the national red list based on the IUCN's conservation-actions template file. Priority species lists will strongly influence prioritization of conservation actions at national levels, but action should not be exclusive to listed species. In addition, all species on this list will not necessarily require immediate action. Our method is transparent, reproducible, and readily applicable to other taxa and regions.