1,721,167 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Single calcium channel (CaV1.3) activity recorded from mouse cochlear inner hair cells
No full textVoltage-gated Ca2+ channels expressed in inner hair cells (IHCs) of the mammalian cochlea play a number of key physiological roles in their normal development and sound transduction (Housley et al. 2006, J Memb Biol 209:89-118). Ca2+ influx into IHCs occurs mainly (>90%) through Cav1.3 L-type Ca2+ channels (Platzer et al. 2000, Cell 102:89-97; Brandt et al 2003, J Neurosci 23:10832-40). Although some of the macroscopic biophysical properties of CaV1.3 Ca2+ channels are known, their elementary properties have yet to be determined in mammalian IHCs.
Single Ca2+ channel activity was recorded at body temperature from immature IHCs in cell-attached configuration using acutely dissected mouse organs of Corti. Voltage-dependent Ca2+ channels were investigated using Ba2+ in the patch pipette solution as the main charge carrier and Bay K 8644 to resolve the channel openings. Cell-attached recordings confirmed the presence of L-type Ca2+ channels, which showed a slope conductance of 39.0 pS and 17.6 pS in 70 mM and 5 mM Ba2+, respectively. The mean half maximum open probability (V1/2) significantly shifted from about ñ22 mV in 70 mM Ba2+ to ñ41 mV in 5 mM Ba2+. The voltage threshold for Ca2+ channel activation was also significantly less hyperpolarized in 70 mM Ba2+ than in 5 mM Ba2+. The maximum and the minimum open probability were: 0.120 and 0.005 in 5 mM Ba2+ and 0.042 and 0.002 in 70 mM Ba2+.
The present results are consistent with mammalian IHCs expressing a homogeneous population of voltage-dependent L-type Ca2+ channels containing the alpha1D (CaV1.3) subunit. The hyperpolarized activation of these Ca2+ channels indicate that they are likely to be active at the presumed resting membrane potential of IHCs, thus supporting spontaneous action potential activity characteristic of pre-hearing IHCs (Marcotti et al. 2003, J Physiol 552:743-761)
Properties of the single calcium channels CaV1.3 in mouse cochlear inner hair cells
No full textInner hair cells (IHCs) of the adult mammalian cochlea respond to sound stimuli with small and graded receptor potentials. Before the onset of hearing immature IHCs fire spontaneous Ca2+ action potentials. Both types of response lead to Ca2+ inflow through voltage-gated Ca2+ channels that causes neurotransmitter release at IHC ribbon synapses onto afferent fibres (Moser & Beutner 2000). More than 90% of the Ca2+ inflow occurs through the Cav1.3 L-type Ca2+ channels (Platzer et al. 2000), the single channel kinetics of which have yet to be determined.
METHODS: Single Ca channel activity was recorded in the “cell-attached” configuration (patch-clamp technique) from the mouse immature IHCs near body temperature. Voltage steps were applied from the holding potential of –70 mV. The patch pipette solution contained 5 or 70 mM of Ba2+ as the ion carrier and Bay K 8644 to better resolve the single channel openings.
RESULTS: L-type Ca channels showed a slope conductance of 39 pS and 17.6 pS in 70 and 5 mM Ba2+ respectively. The channel showed two open time constants at all voltages (at –30 mV the time constants were 0.4 and 4.9 ms with 5 mM Ba2+, and 0.4 and 1.5 ms with 70 mM Ba2+). Only the slower time constant was clearly voltage-dependent. Three closed states were found, of which only the longest was clearly voltage-dependent. Time-to-first opening distributions were fit by two time constants of which one was very fast (<1 ms).
CONCLUSIONS: IHCs L-type Ca channels show multiple gating states, some of which are voltage-dependent. The kinetics properties of the single Ca2+ channels recorded in the immature IHCs are consistent with the ribbon synapses sustaining a fast and precise release onto the afferent terminal (Goutman and Glowatzki 2007)
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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