1,720,960 research outputs found
Petrogenesis of mafic lavas from the northernmost sector of the Iblean district (Sicily)
No full textA wide spectrum of mafic volcanic rocks, ranging from Qz-tholeiites to strongly undersaturated alkaline lavas (ankaratrites), were erupted during Upper Miocene and Plio-Pleistocene in the Iblean area. The rather primitive nature of these products indicates that the differentiation processes occurred from the source region to the surface affected these magmas only in subordinate way.For this reason, on the basis of the presented chemical and mineralogical data, the petrogenetic study of the Iblean volcanic suite is mainly aimed at constraining and evaluating the partial melting processes and the nature of the mantle sources. The modelling of the available chemical data (both major and trace elements) indicates that these near-primary melts cannot have been produced by different degrees of melting from the same source; this would suggest that their differences reflect, at least in part, significant variations in source composition.The calculations suggest that suitable mantle sources are represented by variously "enriched" spinel-lherzolites, containing accessory phases such as amphibole for tholeiitic and transitional basalts (A-Th, B-Th and TB), amphibole + phlogopite for alkaline lavas (AB, Bn) and amphibole + phlogopite +/- apatite +/- carbonate for highly alkaline rocks (A-Ank, B-Ank).In this light, the wide range of mafic lavas collected in the Iblean area appear to have been produced by different degrees of partial melting, ranging from 2-3% for the highly alkaline rocks to 22 % for the Qz-tholeiites, of a lithospheric mantle characterized by small-scale heterogeneity.This process has been favoured by relatively high thermal conditions in the mantle beneath the studied area and induced by the Miocene and Plio-Pleistocene transcurrent-extensional tectonic regime.The chemical compositions of the various lavas depend on the relative proportions of the differently enriched mantle domains involved. Small degrees of partial melting sampled preferentially low-solidus enriched domains, producing the alkaline magmas. At higher partial melting degrees, larger domains of less enriched mantle portions contributed to the magmatogenetic processes, thus generating the subalkaline magmas
Assessment of a shallow magmatic system: The case of the 1888-90 eruption, Vulcano Island, Italy
No full text
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
- …
