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
Ribosomal cold-adaptation: Characterization of the genes encoding the acidic ribosomal P0 and P2 proteins from the Antarctic ciliate Euplotes focardii
No full textMolecular adaptation at low temperature requires specificities represented mainly by modifications in the gene sequence and consequently in the protein primary structure. To characterize the Molecular mechanisms responsible for ribosome cold-adaptation, we compared the ribosomal P0 and P2 genes from the Antarctic ciliate Euplotes focardii with homologous genes from mesophilic organisms, including the ciliates Tetrahymena thermophilia and non cold-adapted Euplotes species. This analysis revealed the presence of non synonymous mutations unique to E. fiocardii. In the P0 protein the mutations produced amino acid substitutions that increased the molecular flexibility that may facilitate a conformational adjustment associated with the interaction with the GTPase center of the large subunit rRNA, and increased the hydrophobicity of the region involved in the interaction with P1/P2 heterodimer, probably to keep associated the ribosomal stalk in the cold. In the P2 protein the mutations produced amino acid substitutions that increased the N-terminus flexibility, which may facilitate interactions with PI protein in the formation of the heterodimer, and reduced the mobility of the C-terminus, to stabilize the stalk during ribosomal activity. Finally, P proteins appeared to be valid markers for investigating the phylogenetic origin of early eukaryotes
Ribosomal cold-adaptation: characterization of the genes encoding the acidic ribosomal P0 and P2 proteins from the Antarctic ciliate Euplotes focardii.
No full textMolecular adaptation at low temperature requires specificities represented mainly by modifications in the gene sequence and consequently in the protein primary structure. To characterize the molecular mechanisms responsible for ribosome cold-adaptation, we compared the ribosomal P0 and P2 genes from the Antarctic ciliate Euplotes focardii with homologous genes from mesophilic organisms, including the ciliates Tetrahymena thermophila and non cold-adapted Euplotes species. This analysis revealed the presence of non synonymous mutations unique to E. focardii. In the P0 protein the mutations produced amino acid substitutions that increased the molecular flexibility that may facilitate a conformational adjustment associated with the interaction with the GTPase center of the large subunit rRNA, and increased the hydrophobicity of the region involved in the interaction with P1/P2 heterodimer, probably to keep associated the ribosomal stalk in the cold. In the P2 protein the mutations produced amino acid substitutions that increased the N-terminus flexibility, which may facilitate interactions with P1 protein in the formation of the heterodimer, and reduced the mobility of the C-terminus, to stabilize the stalk during ribosomal activity. Finally, P proteins appeared to be valid markers for investigating the phylogenetic origin of early eukaryotes
Different roles of two gamma-tubulin isotypes in the cytoskeleton of the Antarctic ciliate Euplotes focardii: remodelling of interaction surfaces may enhance microtubule nucleation at low temperature
No full textIn ciliates, different microtubular structures are nucleated from diverse Microtubule Organizing
Centers (MTOCs). c-Tubulin is a tubulin superfamily member that plays an essential role in
microtubule nucleation at the MTOCs. However, little is known about mechanisms regulating the
activity of c-tubulin on different MTOCs and during the cell cycle. In Tetrahymena thermophila, the
a- and b-tubulin expression is regulated mainly at the transcriptional level, and changes in the ratio of
polymerized/unpolymerized tubulin dimers lead to an increase or decrease of a- and b-tubulin
transcription. This study deals with the characterization of c-tubulin in the amicronuclear ciliate
Tetrahymena pyriformis. Sequence analysis revealed some specific substitutions in nucleotidebinding
loops characteristic of the Tetrahymena genus and putative conserved phosphorylation sites
located on the external surface of the c-tubulin molecule. c-Tubulin expression during the cell cycle, in
the presence of microtubular poisons and after deciliation, was also characterized. We found that
c-tubulin mRNA levels are correlated with basal body proliferation and c-tubulin nuclear localization.
We also found that c-tubulin expression changes during anti-microtubular drugs treatment, but does
not changes during reciliation. These findings suggest a relationship between the level of
unpolymerized tubulin dimers and c-tubulin transcription
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
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