1,720,990 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
Alteration and corrosion phenomena in Roman submerged glass fragments
No full textIn the present paper the surface analytical techniques of XPS (X-ray photoelectron spectroscopy) and SIMS (secondary ions mass spectrometry) have allowed an understanding of the alteration and corrosion phenomena occurring in Roman glass fragments. The samples come from the seawater archaeological site of the Roman ship Iulia Felix, which sank near Grado (Gorizia, Italy) in the second century A.D. Through XPS the surface concentration of the main chemical elements and their depth profiles have been obtained. Attention has been focused on the oxidation states of the elements, oxygen/silicon ratio, peculiar presence of carbonate salts and concentration trends of some elements in the outer atomic layers. Depth trends of aluminium, calcium, magnesium and carbon were studied also through SIMS depth profiles. The whole set of XPS and SIMS data allows the segregation of particular chemical species and the evolution of the original glass to a multilayer system
Surface study of influence of water on chemical corrosion of roman glass
No full textRoman glass surfaces have been studied to understand water effects on glass degradation and
ionic mobility. Studied specimens mainly come from the Roman ship Iulia Felix, found on the
seabed of Grado lagoon (Italy) and dated to the 2nd century AD. Many different corrosion
features have been investigated including white glass, glossy glass and growth rings. A typical
multilayered structure found in glass is characterised by the presence of different ions in depth
profiles. Layered structure is also underlined by variations in hydration oxygen value and
adventitious carbon content. Evidence of ion mobility can be found in the study of growth rings,
which have metal rich centres rounded with concentric rings. The centres are characterised by
the presence of antimony and titanium in their maximum oxidation state: Sb(V) and Ti(IV). The
evolution can be understood according to ‘Liesegang ring’ kinetics. Data of glass surfaces have
been collected using many techniques, i.e. X-ray photoelectron spectroscopy (XPS), secondary
ion mass spectrometry (SIMS) and environmental scanning electron microscopy (ESEM). Several
bulk techniques to characterise the specimens have been used
Glass Corrosion Through the Alps: A Surface Study of Chemical Corrosion of Glasses Found in Marine and Ground Environment
No full textSol-gel deposition of silica films on silicate glasses: Influence of the presence of lead in the glass or in precursor solutions
No full textMany lead silicate historical glasses suffer degradation phenomena often observed as color changes and iridescence caused by lead ions leaching from the outer layers of the glass. In order to repair and to prevent these phenomena, glasses with large amounts of lead (6.7 and 14.3 at.% of lead) have been coated with silica films at neutral pH by dipping them in a precursor solution of TEOS (tetraethyl orthosilicate), ethyl alcohol and deionized water without any other acid or basic catalyst. Experiments with long dipping times (24 h) and temperatures around 20 °C have been performed to evaluate the role of lead ions of the glass as a catalyst. Silica films of very good quality and optical transparency have been also obtained on lead-free, soda-lime glasses by adding catalytic amounts of Pb(NO3)2 instead of HCl to the precursor solution. The films have been characterized by optical microscopy, AFM (Atomic Force Microscopy), XPS (X-ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectrometry)
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