1,721,050 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
Wild-type opaque2 and defective opaque2 polypeptides form complexes in maize endosperm cells and bind the opaque2-zein target site
No full textThe Opaque2 (O2) basic leucine (Leu)-zipper transcriptional activator controls the expression of several genes in maize (Zea mays). We investigated the phosphorylation extent of wild-type O2 and mutant-defective or mutant-truncated o2 polypeptides in endosperm cells, their subcellular localization, participation in complex formation, and involvement in functional activity. Besides wild type, four mutant alleles (o2T, o2-52, o2It, and o2-676) producing o2 polypeptides and a null transcript allele (o2R) were considered. Observing the effects of these mutations, multiphosphorylation events in O2 or o2 proteins were confirmed and further investigated, and the involvement of both the nuclear localization signal (NLS)-B and Leu-zipper domains in proper targeting to the nucleus was ascertained. The absence of these domains in the o2T and o2It-S mutant-truncated forms holds them within the cytoplasm, where they are partially phosphorylated, whereas the presence of NLS-B and a partial Leuzipper domain in o2-52 distributes this mutant-truncated form in both cytoplasm and nucleus. Although mutated in the NLS-B domain, the o2It-L and o2-676 mutant-defective forms are, respectively, partially or completely distributed into the nucleus. Only wild-type O2 and mutant-defective o2 polypeptides bearing the Leu-zipper are able to form complexes whose components were proven to bind the O2-zein target site by in vitro analyses. The transcription of a subset of H-zein genes as well as H-zein polypeptide accumulation in several o2-mutant-defective genotypes indicate the in vivo involvement of o2-mutant-defective proteins in O2-zein target site recognition. The gathered information broadens our knowledge on O2 functional activity and our view on possible quality protein maize trait manipulation or plant transformation via the utilization of cisgenic elements
Avian TAP genes : detection of nucleotide polymorphisms and comparative analysis across species
No full textTAP1 and TAP2 genes code for the two subunits of the transporter associated with antigen processing (TAP), and in chicken they are located between the two MHC class I genes. Using primers based on chicken sequences, the genomic regions corresponding to chicken TAP1 exons 6 to 7 and TAP2 exons 4 to 6 (which encode portions of the chicken TAP1 and TAP2 molecules corresponding to the human peptide-binding regions) were amplified and sequenced from chicken (70 birds), turkey (24), pheasant (6), and guinea fowl (7). A total of 80 within-species single nucleotide polymorphisms (SNPs) were identified. None of the chicken SNPs detected here was present in public databases. The SNP frequencies in chicken were 9.57 SNP/kb in TAP1 and 19.16 SNP/kb in TAP2, while turkey showed similar SNP frequencies in the two genes. Putative amino acid sequences were inferred to identify non-synonymous substitutions. The alignment of the consensus polypeptide sequences showed that most of the amino acid variations were conserved or semi-conserved substitutions. In conclusion, a high variability in the level of nucleotide polymorphism was observed within the two genes, with chicken showing the highest polymorphism rate in both genes. Most of the SNPs identified were within introns, and a general conservation of both amino acid numbers and characteristics of residues among and within the species was found. These data underline the functional importance of these molecules, but also suggest their capacity to bind different antigenic peptides
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