1,721,000 research outputs found
Optimizing Measures of Information Encoding in Astrocytic Calcium Signals
No full textWhile most models of brain information encoding focus on neurons, recent studies have shown that calcium dynamics of astrocytes, the major class of non-neural cells in the brain, can add information about key cognitive variables that is not found in the activity of nearby neurons. This raises the question of what could be the contribution of astrocytes in information processing, and calls for analysis tools to characterize this contribution. Here we construct simulations with realistic dependencies of astrocytic activity on external variables and we use these simulations to understand how to optimally set parameters of information theoretic analysis of astrocytic activities. Applications of our techniques to simulated and real astrocytic data show how to set parameters of information analyses that provide conservative, yet reliable, estimates of astrocytic calcium dynamics contribution to circuit-level brain information processing
Modal gating of human Ca(v)2.1 (P/Q-type) calcium channels: I. The slow and the fast gating modes and their modulation by beta subunits
Full text linkThe single channel gating properties of human Ca(V)2.1 (P/Q-type) calcium channels and their modulation by the auxiliary beta(1b), beta(2c), beta(3a), and beta(4a), subunits were investigated with cell-attached patch-clamp recordings on HEK293 cells stably expressing human Ca(V)2.1 channels. These calcium channels showed a complex modal grating. which is described in this and the following paper (Fellin, T., S. Luvisetto, M. Spagnolo, and D. Pietrobon. 2004. J Gen. Physiol. 124:463-474). Here, we report the characterization of two modes of gating of human Ca(V)2.1 channels, the slow mode and the fast mode. A channel in the two gating modes differs in mean closed times and latency to first opening (both longer in the slow mode), in voltage dependence of the open probability (larger depolarizations are necessary to open the channel in the slow mode), in kinetics of inactivation (slowed in the slow mode), and voltage dependence of steady-state inactivation (occurring at less negative voltages in the slow mode). Ca(V)2.1 channels containing any of the four beta subtypes can gate in either the slow or the fast mode, with only minor differences in the rate constants of the transitions between closed and open states within each mode. In both modes; Ca(V)2.1 channels display different rates of inactivation and different steady-state inactivation depending oil the P subtype. The type of beta subunit also modulates the relative occurrence of the slow and the fast gating mode of Ca(V)2.1 channels, beta(3a), promotes the fast mode, whereas beta(4a) Promotes the slow mode. The prevailing mode of gating, of Ca(V)2.1 channels lacking a beta subunit is a gating mode in which the channel shows shorter mean open times, longer mean closed times, longer first latency, a much larger fraction of mills, and activates at more positive voltages than in either the fast or slow mode
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
Modal gating of human Ca(v)2.1 (P/Q-type) calcium channels: II. The b mode and reversible uncoupling of inactivation
No full texthe single channel gating properties of human Ca(V)2.1 (P/Q-type) calcium channels were investigated with cell-attached patch-clamp recordings on HEK293 cells stably expressing these calcium channels. Human Ca(V)2.1 channels showed a complex modal gating, which is described in this and the preceding paper (Luvisetto, S., T. Fellin, M. Spagnolo, B. Hivert, RE Brust, M.M. Harpold, K.A. Stauderman, M.E. Williams, and D. Pietrobon. 2004. J Gev. Physiol. 124:445-461). Here, we report the characterization of the so-called b gating mode. A Ca(V)2.1 channel in the b gating mode shows a bell-shaped voltage dependence of the open probability and a characteristic low open probability at high positive voltages, that decreases with increasing voltage, as a consequence of both shorter mean open time and longer mean closed time. Reversible transitions of single human Ca(V)2.1 channels between the b gating mode and the mode of gating in which the channel shows the usual voltage dependence of the open probability (nb gating mode) were much more frequent (time scale of seconds) than those between the slow and fast gating modes (time scale of minutes; Luvisetto et al., 2004), and Occurred independently of whether the channel was in the fast or slow mode. We show that the b gating mode produces reversible uncoupling of inactivation in human Ca(V)2.1 channels. In fact, a Ca(V)2.1 channel in the b gating mode does not inactivate during long pulses at high positive voltages, where the same channel in both fast-nb and slow-jib gating modes inactivates relatively rapidly Moreover, a Ca(V)2.1 channel in the b gating mode shows a larger availability to open than in the rib gating modes. Regulation of the complex modal gating of human Ca(V)2.1 channels could be a potent and verb satile mechanism for the modulation of synaptic strength and plasticity as well as of neuronal excitability and other postsynaptic Ca2+-dependent processes
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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