1,720,994 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
Sulle rotte linguistiche dei genovesi d’Oltremare: prime analisi di un corpus di atti rogati in latino a Chio nel XIV secolo
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Characterization of thin films for TNSA laser irradiation
Full text linkThin films of hydrogenated materials have been prepared, at Messina University, to be irradiated by high intensity lasers in TNSA conditions in order to accelerate high energetic protons with high yield and directivity. Film composition was based on polymers, metals, multilayers and nanostructures embedded in polymers. The preparation methods were different and based on different deposition techniques. High vacuum condition, nanostructures, carbon nanotubes, metal oxides and hydrates, were employed. Targets were prepared as a sheath with thicknesses ranging between 0.1 and 100 μm and surfaces of the order of some cm2. Targets were characterized in terms of thickness, roughness, surface morphology, colours and absorption coefficient in the wavelength range 250 nm-1300 nm. Peculiar attention is given to samples with high absorption coefficient in order to improve the energy transfer from the coherent light to the generated plasma. © Published under licence by IOP Publishing Ltd
Compositional and structural properties of deuterated plasma enhanced chemical vapor deposited silicon-carbon alloys
No full textHydrogenated and deuterated amorphous silicon carbon films were prepared by plasma enhanced chemical vapour deposition (PECVD) starting from silane and deuterated methane gas mixtures. The gas percentages was varied in order to produce films with different carbon and silicon content. The elemental composition was determined by Rutherford backscattering and elastic recoil detection analysis and the bonding structure by infrared spectroscopy. The hydrogen plus deuterium atomic fraction, in the grown films, is about 0.36, almost independent of the film composition. However, the concentration of hydrogen or deuterium depends on the carbon content. In silicon-rich samples both hydrogen and deuterium atoms are contained in the films; with increasing carbon content, the hydrogen concentration decreases and the deuterium concentration increases. At the highest carbon concentration (0.28) the resulting films are fully deuterated with the deuterium atoms attached both to silicon and carbon. From infrared absorption analysis, information on plasma chemistry and surface or bulk reactions during film growth was obtained. For the first time the experimental determination of the origin of the bonded hydrogen in amorphous SiC:H films, grown by methane-silane PECVD, is reported. Comparison of elemental composition and infrared spectra of films grown from hydrogenated and deuterated methane shows that hydrogen exchange occurs between carbon and silicon atoms. Moreover, as the films approach stoichiometry the hydrogen incorporated into the sample originates mainly from methane gas
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