1,720,966 research outputs found
Plume activity, magmatism, and the geodynamic evolution of the Central Mediterranean
No full textOn the basis of isotopic and geochemical data we propose that most of the volcanic activity in Italy is plume rather than subduction related. We suggest that a large plume underlies the Tyrrhenian Sea, extending westwards under Sardinia and Corsica, northwards towards the Western Alps and eastwards under the Italian mainland. The plume is isotopically defined in terms of three end-members, different from any of those found in subduction-related environments. Two of the end-members are similar to the FOZO and EM1 mantle components defined on the basis of data from OIBs, while a third, here called ITEM (ITalian Enriched Mantle), is characterized by a high 87Sr/86Sr ratio (> 0.7200) and quite different from any component found in oceanic environments. The two trends that emerge in isotope ratio diagrams indicate mixing between a common end-member (FOZO) and the two others. Implied by the presence of a common end-member is the involvement of a common source and a single large-scale geodynamic system. Partial melting of an isotopically heterogeneous plume head containing both source and entrained material is one way to explain many of the features that characterize Italian magmatism. Widespread extensional tectonics, lithospheric thinning, and deep-seated CO2 emissions add further support to mantle plume activity in Italy
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Reply to: "Carbonate-rich pyroclastic rocks from central Apennines: carbonatites or carbonated rocks? A commentary". A. Peccerillo
No full textIn a recent paper Peccerillo (2004) quoted chemical, including isotopic, mineralogical and field data which he claimed "..cast serious doubt on the hypothesis that the carbonate-rich pyroclastics from central Italy represent carbonatitic magmas.". He concluded that the carbonate is derived from sedimentary limestone. He also noted that he had enunciated these ideas earlier (Peccerillo, 1998) but that he had not been answered and further that "the Editor of this journal [Periodico di Mineralogia] has repeatedly asked me to set down my case again and I have, reluctantly, agreed to do so.". We, some of the principal advocates of the carbonatitic interpretation for the igneous carbonate-rich rocks of central Italy, have, therefore, taken this opportunity to answer, in detail, the various arguments advanced by Peccerillo. We remain firmly convinced that the evidence demonstrates that the carbonate-rich rocks at the five localities of San Venanzo, Cupaello, Polino, Oricola and Vulture are carbonatitic, the carbonate deriving from deep within the mantle, and that sedimentary limestones played no immediate part in their genesis
Reported data and interpretation of some wollastonite- and melilite-bearing rocks from the Central Apennines of Italy
No full textTwo distinct occurrences of wollastonite- and melilite-bearing rocks from Ricetto and Colle Fabbri, which are located in the central Italy Apennine Range, are referred to as “paralavas“ generated by melting and recrystallization of marly sediments “likely due to coal fires“ by Melluso et al. (2003). We submit data demonstrating that these conclusions are incorrect. Ricetto is clearly pyrometamorphic, as described by Capitanio et al. (2001, 2004). Colle Fabbri is clearly an igneous outcrop as described in Stoppa (1988). It is quite different in scale, field relationships, and chemistry, and thus Ricetto is irrelevant to its petrogenesis. The sediment mixing model of Melluso et al. (2003) does not relate to the Colle Fabbri field data. Furthermore, the Ricetto Miocene flysch country-rock and the Colle Fabbri enclosing Pliocene clays were not analyzed by Melluso et al. (2003). A limestone-shale mixing calculation using Sr and Nd isotopic data in Melluso et al. (2003, Tables 3 4) and a 143Nd/144Nd ratio of 0.51213 for Apennine shales (op.cit. p. 1297) fails to account for the Colle Fabbri samples, which remain well clear of the hypothetical mixing line. Rocks of mantle origin, including micaceous kimberlites and Western Australia lamproites, plot in the variation field of Colle Fabbri and regionally associated igneous rocks. Colle Fabbri is but one of a series of similar igneous melilite-bearing and carbonatite occurrences that constitute the Intramontane Ultra-alkaline Province of central Italy (IUP), although Colle Fabbri does have unique features, as do other of these occurrences (Stoppa et al. 2003)
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