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BERYL FROM MIAROLITIC POCKETS OF GRANITIC PEGMATITES, ELBA, ITALY: CHARACTERIZATION OF CRYSTAL CHEMISTRY BY MEANS OF EMP AND SIMS ANALYSES
No full textCrystals of beryl from miarolitic pockets, hosted in pegmatitic dikes on the Island of Elba, in Italy, were analyzed for the major and minor elements, including the light elements, by EMPA and SIMS techniques. Back-scattered electron (BSE) images and X-ray maps were used to define the complex textures of these crystals and to highlight the pattern of element distribution in each sample. The majority of the analyzed crystals exhibit a complex pattern of zoning caused by changes in the chemical composition, which follow the main mechanisms of substitution defined for the crystal chemistry of beryl. The following main features are illustrated: (1) the occurrence of crystals with octahedral-site or tetrahedral-site substitutions in different domains of the same crystal, (2) the occurrence of crystals with exclusively tetrahedral or exclusively octahedral substitutions, and (3) the occurrence of crystals or crystal domains having a limited extent of octahedral-site and tetrahedral-site substitutions. However, the analytical data confirm the presence of a gap between the two series, having octahedral-site or tetrahedral-site substitutions. The observed enrichment in Cs and Li is strictly related to the geochemical and petrological features of the LCT host pegmatites. The presence of Ca in some beryl crystals in pegmatites emplaced in carbonate rocks suggests an interaction of the late hydrothermal fluids with country rocks. An enrichment in Fe could also be ascribed to the circulation of fluids having such a contaminant element attributed to the contribution of country rocks or the destabilization of early-crystallized Fe-rich minerals
Benthic foraminiferal assemblages in active volcanic area of the Azores Islands (North Atlantic Ocean)
No full textThe present study shows the preliminary micropalaeontological results obtained from surface samples collected during an Eurofleet marine geological survey in the Terceira offshore (Azores Archipe - lago, Portugal) carried out in September 2011. Benthic foraminiferal assemblages were studied in order to obtain a sea-floor ecological characterisation in natural stressed environments like active volcanic area of the Azores Islands. Sediments were collected at water depths ranging between 260 and 410 m and consist of blackish, sand-sized glass shards, in which highly vesicular
to scoriaceous clasts prevail on fluidal striated fragments. All samples were stained with Rose Bengal to determine living and dead assemblages.
The dominance of living specimens suggests that the first
generation of foraminiferal colonisers was found. Diversity index
(α-Fisher index), Faunal density and Foraminiferal Abnormality Index (FAI) were calculated to assess the structure of the assemblage and the
degree of environmental stress. Living and dead assemblages are very similar; they are very scarce but sufficiently diversified. The living benthic assemblage is dominated by epi/shallow infaunal species Angulogerina angulosa and typical infaunal taxa like Bolivina spp. Subordinately other epifaunal (Ehrenbergina bradyi, Lenticulina spp., Quinqueloculina seminula, Stomatorbina concentrica) and agglutinated species (Ammoglobigerina globigeriniformis, Eggerelloides scabrus, Haplophragmoides canariensis, Spiroplectinella wrightii, Textularia spp.) are also recorded. Significant frequencies of specimens showing signs of test decalcification were found. These test alterations could be due to hydrothermal fluids, since similar features were recorded in foraminiferal specimens coming from other volcanic substrates in the Aeolian Arc (Tyrrhenian Sea). The dominance of living and dead
A. angulosa specimens allows us to consider this species as opportunistic pioneer taxon able to colonise stressed environments. This is confirmed also by the highest values of FAI (>2%), recorded in most of the samples, indicating a persisting environmental stress. Angulogerina angulosa and Bolivina spp. are the species showing more abundant deformed specimens (irregular development of chambers and aberrant tests). On the basis of our observations, the recolonisation process and the spatial distribution patterns are strongly influenced by the sea bottom high hydrodynamic regime which is responsible for volcanic deposit transport and depositional events. These conditions may be reflected on the relationship between benthic foraminifers and substrate features, which are mainly restricted to grain size, morphology and texture of volcanic shards
The Plio-Pleistocene sedimentation on the sediment-starved Pontine continental slope (Tyrrhenian Sea, Italy): A complex history
No full text[No abstract available
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
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