1,721,064 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
Subduction-related enrichment of the Phlegrean Volcanic District (Southern Italy) mantle source: new constraints on the characteristics of the sedimentary components
No full textThe Neapolitan volcanic area (Southern Italy), which includes the Phlegrean Volcanic District and the Somma–
Vesuvius complex, has been the site of intense Plio-Quaternary magmatic activity and has produced volcanic
rocks with a subduction-related geochemical and isotopic signature. High-Mg, K-basaltic lithic lava fragments
dispersed within hydromagmatic tuff of the Solchiaro eruption (Procida Island) provide constraints on the nature
and role of both the mantle source prior to enrichment and the subduction-related components. The geochemical
data (Nb/Yb, Nb/Y, Zr/Hf) indicate a pre-enrichment source similar to that of enriched MORB mantle. In order to
constrain the characteristics of subducted slab-derived components added to this mantle sector, new geochemical
and Sr–Nd-isotopic data have been acquired on meta-sediments and pillow lavas from Timpa delle Murge
ophiolites. These represent fragments of Tethyan oceanic crust (basalts and sediments) obducted during the
Apennine orogeny, and may be similar to sediments subducted during the closure of the Tethys Ocean. Based
on trace element compositions (e.g., Th/Nd, Nb/Th, Yb/Th and Ba/Th) and Nd-isotopic ratio, we hypothesize
the addition of several distinct subducted slab-derived components to the mantle wedge: partial melts from
shales and limestones, and aqueous fluids from shales, but the most important contribution is provided by
melts from pelitic sediments. Also, trace elements and Sr–Nd-isotopic ratios seem to rule out a significant role
for altered oceanic crust. Modeling based on variations of trace elements and isotopic ratios indicates that the
pre-subduction mantle source of the Phlegrean Volcanic District and Somma–Vesuvius was enriched by 2–4%
of subducted slab-derived components. This enrichment event might have stabilized amphibole and/or phlogopite
in the mantle source. 6% degree of partial melting of a phlogopite-bearing enriched source, occurring initially
in the garnet stability field and then in the spinel stability field can generate a melt with trace elements and Sr–
Nd-isotopic features matching those of high-Mg, K-basalts of Procida Island. Furthermore, 2% partial melting of
the same enriched source can reproduce the trace elements and isotopic features of the most primitive magmas of Somma–Vesuvius, subsequently modified by assimilation of continental crust during fractional crystallization processes at mid-lower depth. Combined trace element and Sr–Nd isotope modeling constrains the age of the enrichment event to 45 Ma ago, suggesting that the Plio-Quaternary magmatism of the Neapolitan area is postorogenic, and related to the subduction of oceanic crust belonging to the Tethys Ocean
Multiple refertilisation of oceanic mantle: new insights into the evolution of the southern sector of the Ligurian Tethys from Mt. Pollino ophiolites (Basilicata, Southern Italy).
No full textEstudio petrológico del volcanismo cuaternario de los Monti Cimini y el volcán de Vico, Lazio, Italia
No full textThis paper provides new geochemical, petrographic, and isotopic data over a set of 39 samples representative of all different units present in the quaternary volcanism of Monti Cimini region (Provincia Magmatica Toscana) and Vico volcano (Provincia Magmatica Romana). Monte Cimini volcanics are older in age (around 0.94 Ma) includes trachytic and latitic rocks with isotopic ratios 87Sr/86Sr 0.713413+-14 a 0.715685+-5, and 143Nd/144Nd 0.512053+-3 to 0.5121339+-3. Vico volcano (0.4 Ma) products range between phonolitic and trachyandesitic compositions and shows 87Sr/86Sr values of 0.710923+-5 a 0.711264+-6 and 143Nd/144Nd 0.512092+-3 to 0.512122+-3. All these new data are in good agreement with their former attribution to the aforementioned magmatic province
Estudio petrológico del volcanismo cuaternario de los Monti Cimini y el volcán de Vico, Lazio, Italia
No full textThis paper provides new geochemical, petrographic, and isotopic data over a set of 39 samples representative of all different units present in the quaternary volcanism of Monti Cimini region (Provincia Magmatica Toscana) and Vico volcano (Provincia Magmatica Romana). Monte Cimini volcanics are older in age (around 0.94 Ma) includes trachytic and latitic rocks with isotopic ratios 87Sr/86Sr 0.713413„b14 a 0.715685„b5, and 143Nd/144Nd 0.512053„b3 to 0.5121339„b3. Vico volcano (0.4 Ma) products range between phonolitic and trachyandesitic compositions and shows 87Sr/86Sr values of 0.710923„b5 a 0.711264„b6 and 143Nd/144Nd 0.512092„b3 to 0.512122„b3. All these new data are in good agreement with their former attribution to the aforementioned magmatic provinces
Subduction-related enrichment of the Phlegrean Volcanic District (Southern Italy) mantle source: new constraints on the characteristics of the sedimentary components
No full textEstudio petrologico del volcanismo cuaternario de los Monti Cimini y el volcan de Vico, Lazio, Italia
No full text- …
