1,721,002 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
The Segment Polarity Pattern After Cell Proliferation
No full text<div><p>(A) Parasegments in the segment polarity pattern during cell proliferation. During cell proliferation, each cell duplicates into two cells that initially have identical gene expression. This yields wide stripes of <i>wg</i> and <i>en</i> expression at parasegment boundaries immediately after cell proliferation. Subsequently, differences in intercellular signaling cause the stripes of <i>wg</i> and <i>en</i> narrow.</p>
<p>(B) A simple set of rules sufficient to maintain narrow boundaries after cell proliferation. These are like the simple rules in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020123#pbio-0020123-g001" target="_blank">Figure 1</a>C, but <i>wg</i> expression also depends on a <i>hh</i>-expressing neighbor.</p></div
The Segment Polarity Pattern and the Behavior of Different Cells
No full text<div><p>(A) Parasegments in the segment polarity pattern. The prepattern, with stripes of <i>wg</i> and <i>en</i> expression, and the final segment polarity pattern are shown. The parasegment is the basic developmental unit in the segment polarity pattern, but segment boundaries within the adult insect are offset from the parasegment boundary.</p>
<p>(B) A simple set of rules sufficient to achieve segment polarity patterning. Cells expressing <i>wg</i> must continue to express <i>wg, en</i>-expressing cells must continue to express <i>en</i> and begin expressing <i>hh</i>, and cells expressing neither <i>wg</i> nor <i>en</i> cannot begin expressing either.</p>
<p>(C) The behavior of isolated cells for parameter sets that form the segment polarity pattern. These are like the simple rules in (B), but <i>en</i> expression depends on a <i>wg</i>-expressing neighbor.</p></div
Inequalities Necessary for Bistability in the Modified Segment Polarity Model
No full text<div><p>(A) Intercellular WG levels in a cell that expresses <i>wg</i> (green) and that does not express <i>wg</i> (red) were plotted against K<sub>WG→wg</sub>for each parameter set that forms the segment polarity pattern, as in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020123#pbio-0020123-g004" target="_blank">Figure 4</a>B. In both cases, cells are receiving maximal HH signal from two neighbors.</p>
<p>(B) Intercellular WG levels in a cell that is expressing <i>wg</i> but is no longer receiving HH signal from any neighbors were plotted against K<sub>WG→wg</sub>. Parameter sets that can produce the proper pattern after proliferation, including narrow stripes of <i>wg</i> expression, are shown in green while those that fail to do so are shown in red.</p></div
The Regulatory Networks in the Segment Polarity Models
No full text<div><p>(A) The regulatory network used in the <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020123#pbio-0020123-von2" target="_blank">von Dassow et al. (2000)</a> model. Dashed lines indicate interactions added by the original authors in order to achieve proper patterning, while solid lines indicate interactions based on experimental observations. The positive feedback system including <i>wg</i> is in blue, while the one involving <i>en</i> is green and red. The <i>en</i> feedback involves mutual inhibition of <i>en</i> and <i>ci,</i> so one side of the mutual inhibition scheme is drawn in green while the other is drawn in red. When the green species are active, they will repress the red ones, and vice versa. Adapted from <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020123#pbio-0020123-von2" target="_blank">von Dassow et al. (2000)</a>.</p>
<p>(B) The regulatory network of the model developed here. The positive feedback systems are colored as in (A). The <i>en</i> feedback involves mutual inhibition of <i>slp,</i> however, and <i>ci</i> does not play a role in the <i>en</i> feedback system.</p></div
Inequalities Necessary for Bistability Are Satisfied by Working Parameter Sets
No full text<div><p>(A) Subnetwork responsible for <i>wg</i> expression bistability. Levels of intercellular WG in a cell with full <i>wg</i> expression and in an adjacent cell can be computed from the transfer rates <i>Endo<sub>WG</sub>, Exo<sub>WG</sub>, LMxfer<sub>WG</sub>,</i> and <i>Mxfer<sub>WG</sub></i>; and the decay rates <i>H<sub>EWG</sub></i> and <i>H<sub>IWG</sub></i>, using the linearity of WG transport processes.</p>
<p>(B and C) Intercellular WG levels in a cell expressing <i>wg</i> (green) and in an adjacent cell (red) were plotted against K<sub>WG→wg</sub>, the threshold level of intercellular WG protein needed for <i>wg</i> autoactivation. In (B), parameter sets that maintain the segment polarity pattern were used, while in (C) random parameter sets were used.</p>
<p>(D) Levels of extracellular WG signalling to a cell adjacent to two with full <i>wg</i> expression were computed as described above. These were plotted against K<sub>EWG→<i>en</i></sub>, the threshold level of extracellular WG signal needed to activate <i>en</i> expression.</p>
<p>(E) Steady-state levels of CN in the absence of <i>en</i> expression plotted against K<sub>CN┤<i>en</i></sub>, the threshold level needed to repress <i>en</i> expression.</p></div
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
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