1,721,102 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
Novel aqueous sol-gel preparation and characterization of barium M ferrite, BaFe12O19 fibres
No full textGel fibres of barium M ferrite, BaFe12O19, were blow spun from an aqueous inorganic sol and calcined at temperatures up to 1200°C. The ceramic fibres were shown by X-ray diffraction to be single phase crystalline M ferrite at 1000°C, and surface area and porosity measurements indicated an unusually high degree of sintering at this temperature. The fibres also demonstrated a favourable grain structure of less than 0.1 μm at this temperature and maintained a small grain size of less than 4 μm even up to 1200°C, an im portant factor in the magnetic properties of this material
Aligned hexagonal ferrite fibres of Co2W, BaCo2Fe16O27 produced from an aqueous sol-gel process
No full textGel fibres of Co2W, BaCo2Fe16O27, were blow spun from an aqueous inorganic sol and collected as an aligned tow blanket with an alignment of over 90%. Upon calcination up to 1300°C, the ceramic fibres were shown by X-ray diffraction to form single-phase crystalline Co2W at 1200°C, an unusually low temperature for this compound to form as the major phase. The formation of Co2W was also accompanied by sudden grain growth, forming crystallites over 10 μm in length. While this reduced the mechanical strength of the fibres, they were still suitable for use in a composite material
Effect of sodium on the creep resistance of yttrium aluminium garnet (YAG) fibres
No full textAligned YAG fine fibres had been made previously from an aqueous sol-gel process, but it was suspected that sodium contamination in one of the starting materials lessened the creep resistance of the final product. Therefore, sodium-free gel precursor fibres were made using the same process, and upon firing in air at 900 °C these formed pure phase YAG fibres, of 4 μm diameter. When steamed over 200-500 °C for 3 h, the amorphous gel fibre formed single phase nanocrystalline YAG between 400 and 500 °C, an extraordinarily low temperature for this material to crystallise. Upon postfiring up to 1550 °C, grains averaging 0.5 μm and pores of 0.17 μm had formed, but despite this porosity and smaller grain size, the sodium-free fibre exhibited superior creep resistance than the sodium contaminated fibres reported previously by the authors, typically creeping at temperatures 50 °C higher. This demonstrates that even small levels of sodium contamination are harmful to creep resistance in YAG. © 2005 Elsevier Ltd. All rights reserved
The manufacture of partially-stabilised and fully-stabilised zirconia fibres blow spun from an alkoxide derived aqueous sol-gel precursor
No full textAligned fibres of partially stabilised zirconia (PSZ, 4 mol% Y2O3) and fully stabilised zirconia (FSZ, 8 mol% Y2O3), 3-5 μm in diameter, were blow spun from a sol-gel precursor, and then fired to give the ceramic fibre. Various potential sol precursors were investigated and characterised, the optimum being an aqueous sol made from hydrolysed and peptised zirconium iso-propoxide. The resulting zirconia fibres were characterised and their evolution studied by XRD, DTA/TGA and SEM, and their mechanical properties assessed. It was found that both PSZ and FSZ fibres formed poorly crystalline cubic zirconia at only 200°C, which became fully crystalline after firing to 400°C. The cubic form was the only phase seen in the FSZ fibre, whereas the PSZ fibre formed the tetragonal phase after firing between 1000 and 1200°C/3 h, and all fibres were nanocrystalline (grain diameter<0.1 μm). Unusually the monoclinic form of zirconia was never observed in the PSZ fibres. After firing above 1200°C the fibres had a strain to break of 0.59%, and appeared to be well sintered from shrinkage data. They had superior creep resistance to Saffil zirconia fibres, creeping at temperatures 50°C higher
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