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The pre-eruptive volatile content of the most recent basaltic and pantelleritic magmas erupted at pantelleria (Italy)
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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
From magmatic to phreatomagmatic activity through the flashing of a shallow depth hydrothermal system: the 1906 eruption of Vesuvius
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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
Changes of mitochondrial properties in maize seedlings associated with selection for germination at low temperature. Fatty acid composition, cytochrome c oxidase, and adenine nucleotide translocase activity.
No full textMelt inclusion study on the pantelleritic plinian eruption of the Green Tuff, Pantelleria Island.
No full textPantelleria Island is the type locality for the peralkaline rhyolitic rocks called pantellerites. In the last 50 ka, after the Plinian, caldera-forming, Green Tuff eruption, volcanic activity at Pantelleria consisted of effusive and mildly explosive eruptions which mostly vented inside and along the rim of the caldera producing silicic lava flows, lava domes and poorly dispersed pantelleritic pumice fall deposits.
During the last two decades, a wealth of studies focused on melt inclusions in pantellerite magmas, all converging in underlying the H2O-rich character of these melts together with high contents of halogens. Recent study on the volatile content of pantellerites from Pantelleria yielded a pre-eruptive H2O content ≤ 4.9 wt % and P ≤ 1.5 kb [Gioncada e Landi, 2010; Neave et al., 2012] and chlorine up to 0.9 wt% for magmas erupted during the most recent effusive and strombolian activity at Pantelleria. Recent experimental data confirmed the H2O-rich character of these magmas [Di Carlo et al., 2010]. However data on pantelleritic magmas emitted during large explosive eruptions associated with caldera collapses, are up to date sporadic and not exhaustive. Our study is aimed to determine the pre-eruptive volatile contents of the pantellerite magmas erupted in the Green Tuff eruption, the last caldera forming event at Pantelleria.
All melt inclusions analyzed have rhyolitic composition (SiO2 70-72 wt.%, Na2O+K2O 10-11 wt) and show extreme peralkalinity, with an (Na+K)/Al clustering at 2-2.2. Fluorine in MI range between 0.13 and 0.3 wt%, while S (< 350 ppm) is close to, or lower than, the detection limit (200-300 ppm) of the microprobe. Glasses of GT, both MI and matrix glass, are characterized by a chlorine content as high as 1.1 wt%, which remains basically unchanged in the all glass analyzed (between 1 and 1.1 wt%). This value is higher than that found in the younger pantelleritic eruptions of about 0.2-0.3 wt%.
Dissolved H2O contents in MI (measured by FT-IR) cover a range from 1.4 to 4.2 wt.%, which is comparable with the H2O measured in MI from pantelleritic pumices erupted during younger effusive, or mildly explosive, eruptions. The maximum values are slightly lower than the highest content of water found in pantelleritic melts at Pantelleria (4.9 wt%) [Neave at al., 2012]. The CO2 content was always below the detection limit of FT-IR method (50 ppm).
Chemical composition and volatile contents in the pantelleritic melt inclusions of the Green Tuff contributed to:
- derive the entrapment pressure/depth of magma accumulation, using appropriate solubility models;
- compare data derived for the Green Tuff Plinian eruption with data available for effusive and mildly explosive eruption (strombolian), at Pantelleria.
- track volatile build-up with magma evolution, i.e. pre- and syn-eruptive degassing
Mafic inclusions in the silica-rich rocks of the Tolfa-Ceriti-Manziana volcanic district (Tuscan Province, Central Italy): chemistry and mineralogy
No full textAppropriate 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
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