272,279 research outputs found

    Operational significance of the deviation equation in relativistic geodesy

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    Deviation equation: Second order differential equation for the 4-vector which measures the distance between reference points on neighboring world lines in spacetime manifolds. Relativistic geodesy: Science representing the Earth (or any planet), including the measurement of its gravitational field, in a four-dimensional curved spacetime using differential-geometric methods in the framework of Einstein's theory of gravitation (General Relativity).Comment: 9 pages, 4 figures, contribution to the "Encyclopedia of Geodesy". arXiv admin note: text overlap with arXiv:1811.1047

    Bernal and the structure of water

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    Bernal recognised early on the importance of water in biological systems and processes, and hence the need to understand the structure of the liquid if he was to understand its biological functionality. Although the structure of crystalline ice had been solved only a few years earlier, and little was understood about the structures of liquids in general, in 1933 he published what is still regarded as a seminal paper which treated not only the structure of liquid water itself, but also addressed an impressively wide range of problems of ice and ionic solutions. Imaginatively exploiting ideas that were developing at the time, he proposed a model for water that reproduced the main features of its x-ray diffraction pattern. Despite the success of this model, however, he subsequently found it unsatisfactory – ''a delusive approach, postulating a greater degree of order in the liquid than actually exists there''. Building on the very successful ''random packing'' model of simple liquids that he developed in the 1950s and 60s, he was ultimately led to a ''random network'' model that was consistent with the known properties of the individual water molecules, and that again could reproduce a range of experimental data – but this time without the model being too ordered. Todays state of the art experiments essentially verify the underlying validity of his ideal model. And even his 1933 model of the water molecule itself is mimicked in some of the more successful molecular models used in todays computer simulations of aqueous systems

    Information Smoothies: embedding information skills in assessed learning

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    A collaborative project was undertaken in the academic year 2008-09 between Library and lecturing staff at Leeds Metropolitan University to embed information literacy skills within assessed module workbooks. Workbooks were delivered through a Virtual Learning Environment (VLE) alongside face-to-face sessions on specific resources. Although no mechanisms for measuring effectiveness were included in the project plan, the data from the software used (Intute: Informs) has provided an opportunity to discuss possible explanations for usage levels and improvements in future projects

    ins(9;4)(q33;q12q25)

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    Review on ins(9;4)(q33;q12q25), with data on clinics, and the genes involved

    The use of Prezi for customer journeys and customer service excellence

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    As part of Leeds Metropolitan University Libraries and Learning Innovation’s (LLI) commitment to customer service and the revalidation of its Customer Service Excellence (CSE) award, we were looking for a new way to present the ‘customer journeys’ that customers take when using our services. Customer journeys are defined as ‘a method of identifying the key processes that the customer encounters when they interact with the organisation’ (Customer Service Excellence, 2012a.) We wanted to use these journeys to aid our insight into our customers and how they used LLI, and in turn use this information to underpin our service provision

    Interferon as a macrophage activating factor. I. Enhancement of cytotoxicity by fresh and matured human monocytes in the absence of other soluble signals

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    The cytolytic activity ofhuman peripheral blood monocytes in vitro against K-562 human leukaemic target cells was stimulated by human fibroblast (fi-) and leucocyte (a-) interferon (IFN). Stimulation was by up to several times the corresponding control activity, and was observed with freshly isolated monocytes, and with monocytes cultured for various periods up to 10 days. The cytolytic activity of untreated monocytes was detectable at very low effector: target ratios ( < 5: 1), and fell between days 1 and 4 in culture, normally rising again towards the initial activity at day 8; this pattern was also observed when IFN was present continuously, although the activities were then always higher than in the corresponding control cells. Cytolysis showed a lag of about 6 hr, in contrast to that by natural killer (NK) cells, and was routinely measured over 24 hr. The course of stimulation by IFN and its dose-response were studied. Stimulation required the presence of IFN for at least 24 hr, and was maximal with between 1,000 and 10,000 units of IFN/ml. When IFN containing media were removed and replaced with control media, the monocyte activity remained stimulated for at least 4 days. Stimulation by fl-IFN was blocked by a specific antibody to fl-IFN, under conditions in which assayable IFN activity was also neutralized. Several control experiments indicated that the action of IFN was on the monocytes and not on the target cells. The morphological maturation of monocytes was retarded by IFN, even in cultures containing up to 50% serum. The effectiveness of fibroblast IFN indicated that stimulation could not be attributed to the lymphokines which might contaminate a-IFN. The action of IFN did not require simultaneous or antecedent in vitro stimulation by endotoxin. This was indicated both by serum free experiments, and also by others in which polymixin B was used to complex with and render unavailable any endotoxin present. Endotoxin showed an independent stimulatory effect, which could be prevented by polymixin
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