1,721,133 research outputs found
Cell cycle dynamics and their application to calculating in situ growth rates in two heterotrophic protozoa : a flow cytometric approach
No full textCell cycle analysis using flow cytometry has been performed upon two heterotrophic protozoa, Oxyrrhis marina (Dujardin) and Chilomonas paramecium (Ehrenberg) in order to the microzoopankton.Both species displayed cell cycle kinetics which were independent of photoperiodic regime, but which were dependent upon environmental temperature. The division rate response to lowered temperature was primarily mediated by the influence of low temperatures upon pathways in the G2 phase of the cell cycle. In contrast, nutrient-dependent control of the cell cycle occurred via a restriction point control of both the G1 and G2 transit in exponentially dividing populations. The S phase, once initiated, tended to be completed independently of nutrient supply. The specific dependences of both restriction points in each species have been discussed.The influence of cell cycle controls upon the rate of cell cycle resumption in arrested populations was studied to provide a framework of cell cycle progression in environments subjected to periodic nutrient supply. Both factors studied; arrest period and nutrient supply, modulated cell cycle kinetics in both species when cell cycling resumed. Further, the results indicated that in both these protozoa, the 'restriction point' control of G1 and G2 progression probably comprised of two elements; a deterministic pathway for the initiation of cell cycling and probabilistic pathway concerned with the maintenance of cycling toward DNA synthesis or mitosis.The basic cell cycle data obtained during exponential growth experiments was then examined in an attempt to calibrate the cell cycle method for calculating the in situ growth rates of the two species of protoza. The method, based upon asynchronously dividing populations, was found not to be feasible for either of the species studied. Principally, this was due to the presence of a G2 restriction point in both species, which violated the key assumption behind the method.</p
Soil/structure interaction of temporary roadways
No full textA series of tests on model temporary military trackway, subject to vehicle loads, on a soft over-consolidated clay was carried out at the London Geotechnical Centrifuge Centre. Two of the tests were conducted under plane strain conditions and analysed the effects of static and cyclic 'whole vehicle loads' on trackway performance. The other two used a rolling vehicle to impose traffic loads on unjointed and jointed trackway respectively, to assess the effects of trackway joint on the underlying soil and to determine the sequence of events involved in the onset of trackway failure.A series of finite element analyses using the critical state soils program CRISP was undertaken in which it was attempted to model the centrifuge models. Two-dimensional analyses were used to model the plane strain centrifuge tests, and three-dimensional analyses for tests involving the rolling vehicle. A two-dimensional effective stress slip element, and a three-dimensional slip element were developed to assist in re-creating the interface between stiff aluminium trackway and soft clay. The results were in good agreement, allowing further analyses to be carried out with modified soil and trackway properties.The centrifuge tests and finite element analyses showed that soil/trackway failure is not typically caused by bearing capacity failure of the soil, or by degradation of the soil due to cyclic loading. It is due to very high soil/trackway contact stresses generated by the low-bending-stiffness articulated joints causing immediate failure of a thin surface layer of the soil. Soil/trackway displacements accumulate as degraded soil is driven aside and successively deeper layers of soil are exposed.Existing trackway performance could be improved significantly by enhancing its stiffness in the direction of vehicle travel: either by increasing the joint interval, restraining panels against rotation or by designing a new, more effective, trackway system.</p
The mathematical modelling of rock blasting
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:DX172544 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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