1,720,959 research outputs found
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
Evidence that TNF-induced respiratory burst of adherent PMN is mediated by integrin alpha(L)beta(2).
No full textPolymorphonuclear leukocytes (PMN) respond to tumor necrosis factor (TNF) with a respiratory burst (RB) only after adherence to surfaces coated with extracellular matrix proteins such as fibronectin and fibrinogen (permissive substrates) but not with others such as laminin or collagen (nonpermissive substrates). As PMN adherence to both types of surfaces is dependent on beta(2) integrins, we investigated the molecular basis of the different metabolic response to TNF. In particular, we evaluated the relative role of each beta(2) integrin (alpha(L)beta(2), alpha(M)beta(2), and alpha(X)beta(2)) in adherence and O(2)(-) production of PMN residing on fibronectin- and laminin-coated surfaces, which were considered as models of permissive and nonpermissive surfaces, respectively. By using alpha chain-specific monoclonal antibodies (mAb), we show that alpha(M)beta(2) and alpha(X)beta(2) mediate adherence to fibronectin and laminin; alpha(L)beta(2) is not involved in adherence to laminin and has only a minimal contribution in adherence to fibronectin. Furthermore, production of O(2)(-) in response to TNF was induced by immobilized anti-alpha(L)beta(2) but not anti-alpha(M)beta(2) or anti-alpha(X)beta(2) mAb. A strong correlation was also found between expression of alpha(L)beta(2) and TNF-induced RB on fibronectin. Lastly, PMN responded to TNF on laminin with a RB after the inclusion of alpha(L)-specific mAb in the laminin coat. Thus, we conclude that TNF-induced RB by PMN residing on fibronectin is mediated by alpha(L)beta(2) and that alpha(M)beta(2) and alpha(X)beta(2) are likely to play an ancillary role to the signaling activity of alpha(L)beta(2) by facilitating its recruitment to sites of adherence. The nonpermissiveness of laminin appears to be a consequence of its inability to act as a ligand for alpha(L)beta(2
Chloride movements in human neutrophils during phagocytosis: Characterization and Relationship to Granule Release
No full textChloride ion efflux is an early event occurring after exposure of human neutrophils to several soluble agonists. Under these circumstances, a rapid and reversible fall in the high basal intracellular chloride (Cl–i) levels is observed. This event is thought to play a crucial role in the modulation of several critical neutrophil responses including activation and up-regulation of adhesion molecules, cell attachment and spreading, cytoplasmic alkalinization, and activation of the respiratory burst. At present, however, no data are available on chloride ion movements during neutrophil phagocytosis. In this study, we provide evidence that phagocytosis of Candida albicans opsonized with either whole serum, complement-derived opsonins, or purified human IgG elicits an early and long-lasting Cl– efflux accompanied by a marked, irreversible loss of Cl–i. Simultaneous assessment of Cl– efflux and phagocytosis in cytochalasin D-treated neutrophils indicated that Cl– efflux occurs without particle ingestion. These results suggest that engagement of immune receptors is sufficient to promote chloride ion movements. Several structurally unrelated chloride channel blockers inhibited phagocytosis-induced Cl– efflux as well as the release of azurophilic—but not specific—granules. It implicates that different neutrophil secretory compartments display distinct sensitivity to Cl–i modifications. Intriguingly, inhibitors of Cl– exchange inhibited cytosolic Ca2+ elevation, whereas Cl– efflux was not impaired in Ca2+-depleted neutrophils. We also show that FcγR(s)- and CR3/CR1-mediated Cl– efflux appears to be dependent on protein tyrosine phosphorylation but independent of PI3K and phospholipase C activation
Role of intracellular chloride in the reversible activation of neutrophil ß2 integrins: A lesson from TNF stimulation
No full textCommon methodology is inadequate for studies on the microbicidal activity of neutrophils.
No full textMicrobicidal activity of neutrophils is usually measured by colony-counting techniques after cell lysis in distilled water. While studying the effect of the reduced nicotinamide adenine dinucleotide phosphate-oxidase inhibitor diphenyleneiodonium (DPI) on the staphylocidal activity of neutrophils, we obtained inconsistent results: various degrees of inhibition in some experiments and no effect in others. The lysis step, i.e., dilution of neutrophils in distilled water, was the source of error. Cell-associated microorganisms were not dispersed effectively by this treatment. We overcame this problem by using water at pH 11 for cell lysis. Under these conditions, killing was inhibited completely and reproducibly by DPI. Here, we show that cell lysis in distilled water is incomplete and leads to an overestimate of microbial killing. This hinders identification of partial defects and makes complete defects appear as partial. We found that DPI-treated neutrophils and chronic granulomatous disease neutrophils were completely defective in killing of Staphylococcus aureus and Candida albicans and partially defective in killing of Escherichia coli after lysis with water pH 11, whereas after lysis in distilled water, killing of S. aureus and C. albicans was approximately 60% and approximately 70% of control killing, respectively, and killing of E. coli was normal. Likewise, killing of S. aureus by myeloperoxidase-deficient neutrophils was severely impaired after lysis in water pH 11 but appeared normal after lysis in distilled water. As most studies about neutrophil microbicidal activity have been performed using distilled water, our findings indicate that previous data about killing defects and the effects of agents that modulate microbicidal activity of neutrophils should be re-evaluated
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