1,720,986 research outputs found
Raman spectroscopy for fluid inclusion analysis
No full textRaman spectroscopy is a versatile non-destructive technique for fluid inclusion analysis, with a wide field of applications ranging from qualitative detection of solid, liquid and gaseous components to identification of polyatomic ions in solution. Raman technique is commonly used to calculate the density of CO2 fluids, the chemistry of aqueous fluids, and the molar proportions of gaseous mixtures present as inclusions. Raman spectroscopy has been applied to measure the pH range and oxidation state of fluids. The main advantages of this technique are the minimal sample preparation and the high versatility. Present review summarizes the recent developments of Raman spectroscopy in fluid inclusions research to provide support for laboratory analyses. (C) 2011 Elsevier B.V. All rights reserved
An explosive component in a December 2020 Milan earthquake suggests outgassing of deeply recycled carbon
Full text linkCarbon dragged at sub-arc depths and sequestered in the asthenospheric upper mantle during cold subduction is potentially released after millions of years during the breakup of continental plates. However, it is unclear whether these deep-carbon reservoirs can be locally remobilized on shorter-term timescales. Here we reveal the fate of carbon released during cold subduction by analyzing an anomalously deep earthquake in December 2020 in the lithospheric mantle beneath Milan (Italy), above a deep-carbon reservoir previously imaged in the mantle wedge by geophysical methods. We show that the earthquake source moment tensor includes a major explosive component that we ascribe to carbon-rich melt/fluid migration along upper-mantle shear zones and rapid release of about 17,000 tons of carbon dioxide when ascending melts exit the carbonate stability field. Our results underline the importance of carbon-rich melts at active continental margins for emission budgets and suggest their potential episodic contributions to atmospheric carbon dioxide
Late-Alpine rodingitization in the Bellecombe meta-ophiolites (Aosta Valley, Italian Western Alps): Evidence from mineral assemblages and serpentinization-derived H2-bearing brine
No full textWe report on Alpine metamorphic and fluid inclusion evolution of a polyphase rodingite occurrence within the Bellecombe antigorite-serpentinite, exposed in the Piemonte zone of Aosta Valley, NW Italy. Fine-grained rodingitic rocks, derived from a protolith of basaltic dike(s), are cross-cut by a network of at least six vein generations, consisting of chlorite, diopside, and grossular garnet (Type I), andradite-grossular garnet + diopside (Type II), andradite-rich garnet + chlorite (Type III), grossular-rich garnet (Type IV), vesuvianite (Type V), and chlorite (Type VI). The fine-grained rodingite and associated veins reveal a tectono-metamorphic history similar to that of the hosting serpentinite and characterized by an earlier high pressure metamorphism, followed by decompression/re-equilibration under greenschist facies conditions and by final cooling. The fluid inclusion study, performed on primary fluid inclusions in vesuvianite from Type V veins and on secondary fluid inclusions in andradite-rich garnet from Type III veins, revealed that at P = 0.22 GPa and T = 400°C, an H2-bearing (XH2 = 0.010) brine (6 wt.% CaCl2 + 6 wt.% NaCl) with traces of CH4 (XCH4 = 0.002 was introduced into the rock. This fluid had a composition compatible with the Ca-rich H2-bearing, reducing aqueous solutions reported from the serpentinization front. These data point to an important event of rodingitization, probably triggered by hydration of metamorphic olivine, during the late greenschist facies Alpine evolution that was probably triggered by hydration of metamorphic olivine
Redox state of Hyblean mantle xenoliths investigated by crystal chemistry, noble gases and fluid inclusions
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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
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
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