273,104 research outputs found
Operational significance of the deviation equation in relativistic geodesy
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
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
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
Recommended from our members
History revisited: The mammals of South America, a 3-volume series
Book Review of Heine, C. and O’Connor, D. 2014. Teaching information fluency: how to teach students to be efficient, ethical and critical information consumers
ins(9;4)(q33;q12q25)
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
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
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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