1,721,090 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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Aminodimethylalanes (R(1)R(2)NAlMe(2)) as useful synthetic precursors of aminoalane difluorides using trimethyltin fluoride: Crystal structures of (2,6-i-Pr2C6H3)N(SiMe(3))AlMe(2) and (2,6-i-Pr2C6H3)N(SiMe(3))AlF2
No full textAminodimethylalanes R(1)R(2)NAlMe(2) (R(1) = 2,6-i-Pr2C6H3, 2,6-Me(2)C(6)H(3); R(2) = SiMe(3), Si(i-Pr)Me(2), Si(t-Bu)Me(2), Si(2,4,6-Me(3)C(6)H(2))Me(2)) are prepared in high yield via reaction of the respective amine R(1)R(2)NH with trimethylaluminum in n-hexane. Further reaction of (2,6-i-Pr2C6H3)N(SiMe(3))AlMe(2) with 2 equiv of trimethyltin fluoride in toluene affords the aminoalane difluoride (2,6-i-Pr2C6H3)N(SiMe(3))AlF2. An X-ray structural determination of (2,6-i-Pr2C6H3)N(SiMe(3))AlMe(2) shows it to be dimeric with bridging methyl and terminal amino groups. The aminoalane difluoride (2,6-i-Pr2C6H3)N(SiMe(3))AlF2 is trimeric with a six-membered alternating aluminum-fluorine ring. Terminal fluorine atoms are located above and below the ring. Reactions of aminoalanes R(1)R(2)NAlMe(2) with 2 equiv of trimethyltin fluoride in THF yield the monomeric THF adducts R(1)R(2)NAlF(2) . THF
Photoluminescence from surface-oxidized Ge nanoclusters
No full textPhotoluminescence from gas-evaporated Ge nanoclusters consisting of a crystalline core encased in an oxide shell are presented. An as-grown sample shows room temperature luminescence with separate peaks around 357 and 580 nm. Prolonged air exposure of the clusters reduces the Ge core dimensions, and the emission initially at 580 nm shifts to 420 nm; however, the violet luminescence at 357 nm displays no difference. These results indicate that there are two mechanisms involved with light emission from Ge nanoclusters, visible light emission associated with the quantum confinement effect, and violet light emission correlated to luminescent centers. (C) 1998 Elsevier Science B.V
Photoluminescence from Ge clusters embedded in porous silicon
No full textVisible photoluminescence (PL) and Raman spectra of Ge clusters embedded in porous silicon (PS) have been studied. The as-prepared sample shows redshifted and enhanced room temperature PL relative to reference PS. This result can be explained by the quantum confinement effect on excitons in Ge clusters and tunnel of excitons from Si units of the PS skeleton to Ge clusters. One year storage in dry air results in a pronounced decrease in PL intensity but blue-shifted in contrast to reference PS. This phenomenon correlates to the size decrease of macerated Ce clusters and occurrence of "quantum depletion" in Ge clusters. Consequently, only excitons in Si units contribute to PL. (C) 1998 American Institute of Physics
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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