187,690 research outputs found
Substance P reduces acetylcholine-induced currents in isolated bovine chromaffin cells
No full textPatch-clamp techniques were used to examine the effect of substance P on acetylcholine-induced current in bovine chromaffin cells. Cells had been enzymatically isolated and kept in short-term culture. Experiments were performed at 22 degrees C. Under whole-cell voltage-clamp conditions substance P alone (2-10 microM) did not induce ionic currents. Acetylcholine (ACh, 20 microM) at -60 mV induced an inward current that desensitized in the continued presence of ACh. The time course of desensitization was somewhat variable from cell to cell. In most cases it could be fitted by a single exponential with time constant of 8-10 s. Substance P (2-50 microM) applied simultaneously with ACh induced what appeared to be an acceleration of the desensitization process. The time course in the presence of 10 microM-substance P (20 microM-ACh) was best fitted by the sum of two exponentials with time constants of 0.6 s and 5 s respectively. The effect was reversible. The recovery of ACh-induced current from desensitization was not affected by substance P. The time constant for recovery was approximately 7 s in the presence or absence of substance P. Single-channel records showed that the conductance of individual channels was not changed by substance P. The mean open time of single channels was shortened by substance P both at high (20 microM) and at low (0.5 microM) concentrations of ACh. The inverse mean open time varied linearly with substance P concentration. Single-channel responses appeared in bursts and clusters after almost complete desensitization at 20 microM-ACh, as was previously observed in frog skeletal muscle. Substance P dramatically reduced ACh current by increasing interburst intervals while decreasing burst duration and the number of openings per burst. We conclude that substance P inhibits ACh-induced depolarization of chromaffin cells either by increasing the rate of desensitization or by inducing channel blockade, which indirectly enhances desensitization. Possible models of desensitization in the absence and presence of substance P are discussed
Clapham, A. R. ; Tutin, T. G. ; Warburg, E. F. — Flora of the British Isles Illustrations. Part. II. Cambridge, The University Press, 1960
No full textP. J. Clapham, A. R. ; Tutin, T. G. ; Warburg, E. F. — Flora of the British Isles Illustrations. Part. II. Cambridge, The University Press, 1960. In: La Terre et La Vie, Revue d'Histoire naturelle, tome 14, n°4, 1960. p. 238
Chemical signalling in brown bears
No full textNevin, OT ORCiD: 0000-0003-3513-8053In this chapter we present an overview of research conducted to explore the biological significance of chemical signalling in brown bears (from Clapham 2012; Clapham et al 2012, 2013, 2014). This was conducted by assessing scent marking site selection, understanding who are the signallers and receivers, and studying the postures and stereotypithy of marking behaviour. To establish why these behaviours have evolved, the significance of observed signalling behaviours can be
evaluated in terms of their potential fitness benefits. Assessing the function of scent marking in brown bears provides an opportunity to establish its influence on the social behaviour of the species, thus demonstrating the importance of behavioural studies conducted in situ. Collectively, knowledge of this form of social behaviour provides a unique insight into the social complexity of this species
Assessment and testing.
No full textIn this brief article, I discuss the relationship between language testing and the other sub-disciplines of applied linguistics and also the relationship, as I see it, between testing and assessment. The article starts with a brief exploration of the term ‘applied linguistics’ and then goes on to discuss the role of language testing within this discipline, the relationship between testing and teaching, and the relationship between testing and assessment. The second part of the article mentions some areas of current concern to testers and discusses in more detail recent advances in the areas of performance testing, alternative assessment, and computer assessment. One of my aims in this article is to argue that the skills involved in language testing are necessary not only for those constructing all kinds of language proficiency assessments, but also for those other applied linguists who use tests or other elicitation techniques to help them gather language data for research
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Clapham (Christopher) : Liberia and Sierra Leone. An essay in comparative politics
No full textNardin Jean-Claude. Clapham (Christopher) : Liberia and Sierra Leone. An essay in comparative politics. In: Revue française d'histoire d'outre-mer, tome 66, n°244-245, 3e et 4e trimestres 1979. Histoire et politologie en Amérique Latine. p. 483
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Clapham, A. R., Tutin, T.G. et Warburg, E.F. — Excursion Flora of the British Isles. Cambridge, University Press, 1959
No full textBourlière François. Clapham, A. R., Tutin, T.G. et Warburg, E.F. — Excursion Flora of the British Isles. Cambridge, University Press, 1959. In: La Terre et La Vie, Revue d'Histoire naturelle, tome 13, n°4, 1959. p. 349
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
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