1,721,024 research outputs found
Prefrontal and agranular cingulate projections to the dorsar premotor areas F2 and F7 in the macaque monkey
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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
Characterization and Regional Distribution of a Class of Synapses with Highly Concentrated cAMP Binding Sites in the Rat Brain.
No full textA class of putative synaptic terminals with concentrated cAMP binding sites are labelled in unfixed sections of rat brain by means of the ligand 8-thioacetamido fluorescein cAMP (SAF-cAMP), a fluorescent analogue of cAMP. The labelled terminals appear as sharply delimited bouton-like structures in close proximity but external to the cell body of neurons. The SAF-cAMP binding, measured at equilibrium in competition with other nucleotides, indicates that the binding site recognizes the cAMP moiety of SAF-cAMP. In the labelled terminals of the frontal cortex the concentration of SAF-cAMP binding sites is estimated to be in the millimolar range (at least 2.1 +/- 1.0 mM). In a brain homogenate, labelled terminals are visualized only in the membrane fraction enriched in synaptosomes. The cAMP binding activity of the synaptosomes is insoluble in high and in low ionic strength solution and is only partially solubilized by detergents, suggesting that the binding sites are intrinsic membrane proteins and/or proteins associated with the cytoskeleton. There is the possibility that SAF-cAMP labels new cAMP binding sites highly concentrated in a class of synaptic terminals. SAF-cAMP labelling is prominent in well defined regions of the rat brain: (i) the frontal and entorhinal areas of the cortex; (ii) the field CA1 of the hippocampus; (iii) the olfactory system; (iv) the medial nuclei of the thalamus; (v) the parabrachial nuclei and other less defined regions of the reticular substance; (vi) the substantia gelatinosa of Rolando in the spinal cord; and (vii) the neo- and paleocerebellum in the Purkinje cell layer, the archicerebellum in the granular cell layer. SAF-cAMP labelling is absent in specific motor and sensory structures, with the exception of the olfactory system. It is proposed that SAF-cAMP binding sites single out a new type of synaptic terminals involved in complex nervous functions
Neurons related to reaching-grasping arm movements in the rostral part of area 6 (area 6aβ)
No full textSingle neurons were recorded from the rostral part of the agranular frontal cortex (area 6a β) in awake, partially restrained macaque monkeys. In the medialmost and mesial sectors of this area, rostral to the supplementary motor area, neurons were found which were activated during arm reaching-grasping movements. These neurons ("reaching-grasping neurons") did not appear to be influenced by how the objects were grasped nor, with some exceptions, by where they were located. Their activity changed largely prior to the arm movement and continued until the end of it. The premovement modulation (excitatory or inhibitory) could start with stimulus presentation, with the saccade triggered by the stimulus or after stimulus fixation. The distance of the stimulus from the monkey was an important variable for activating many neurons. About half of the recorded neurons showed a modulation of the same sign during movement and premovement period. The other half showed an increase/decrease in activity which was of the opposite sign during movement and premovement period or part of it. In this last case the discharge changes were of the same sign when the stimulus was close to the monkey and when the monkey moved its arm to reach the objects, whereas they were of opposite sign when the stimulus was outside the animal's reach. Microstimulation of area 6a β and the reconstruction of the locations of eye movement and arm movement related cells showed that the arm field was located more medially (and mesially) than the eye field described by Schlag and Schlag-Rey (1987). It is suggested that, unlike inferior area 6, which is mostly involved in selection of effectors on the basis of the physical properties of the objects and their spatial location (Rizzolatti and Gentilucci 1988), area 6a β plays a role in the preparation of reaching-grasping arm movements and in their release when the appropriate conditions are set. © 1990 Springer-Verlag
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