1,720,985 research outputs found
Submarine gas burst at Panarea Island (southern Italy) on November 3, 2002: a magmatic versus hydrothermal episode
No full textSubmarine gas burst at Panarea Island (southern Italy) on 3 November 2002: A magmatic versus hydrothermal episode
No full textOn 3 November 2002, fishermen observed the sudden appearance at the sea surface of three large whitish plumes 3 km offshore of Panarea Island (Aeolian Islands, southern Italy) caused by the uprising from the seafloor of huge columns of gas bubbles, mixed with sediments and colloidal sulfur. The degassing event partly superimposed an already existing gentle-degassing fumarolic field. Since 12 November 2002, a discontinuous geochemical monitoring program of these new discharging fluids have been carried out. The submarine emissions collected on November 2002 were an emulsion made by a CO2-dominated continuous gas phase with suspended sediments, colloidal sulfur, and water condensate microdroplets acidified by dissolution of compounds such as SO2, HCl, and HF. In the gas phase, light-unsaturated hydrocarbons also occurred, possibly related to relatively high temperature and oxidizing conditions due to local input of magmatic fluids at depth, whose occurrence was also supported by the relative high values of 3He/4He isotopic ratio (R/Rair = 4.62) with respect to previously measured values (R/R air < 4.2). The flux of the submarine emissions significantly decreased in a couple of months together with the almost complete disappearance of the magmatic chemical markers and the decrease of the helium isotopic ratio. Thus the most striking feature of the temporal and spatial evolution in the chemical and isotopic compositions of the submarine fumaroles was the relatively rapid restoration, since January 2003, of the precrisis conditions, i.e., typical of a stationary hydrothermal system. Copyright 2007 by the American Geophysical Union
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
Gas isotopic signatures (He, C, and Ar) in the Lake Kivu region (western branch of the East African rift system): Geodynamic and volcanological implications
No full textOn 17 January 2002, the city of Goma was partly destroyed by two of the several lava flows erupted from a roughly N-S oriented fracture system opened along the southern flank of Mount Nyiragongo (Democratic Republic of Congo), in the western branch of the East African rift system. A humanitarian and scientific response was promptly organized by international, governmental, and nongovernmental agencies coordinated by the United Nations and the European Union. Among the different scientific projects undertaken to study the mechanisms triggering this and possible future eruptions, we focused on the isotopic (He, C, and Ar) analysis of the magmatic-hydrothermal and cold gas discharges related to the Nyiragongo volcanic system, the Kivu and Virunga region. The studied area includes the Nyiragongo volcano, its surroundings, and peripheral areas inside and outside the rift. They have been subdivided into seven regions characterized by distinct He/He (expressed as R/Rair) ratios and/or δ13 C-CO2 values. The Nyiragongo summit crater fumaroles, whose R/Rair and δ13 C-CO2 values are up to 8.73 and from -3.5% to -4.0% VPDB, respectively, show a clear mantle, mid-ocean ridge basalt (MORB)-like contribution. Similar mantle-like He isotopic values (6.5-8.3 R/Rair) are also found in CO2-rich gas emanations (mazukus) along the northern shoreline of Lake Kivu main basin, whereas the 13δC- CO2 values range from -5.3% to -6.8% VPDB. The mantle influence progressively decreases in (1) dissolved gases of Lake Kivu (2.6-5.5 R/R air) and (2) the distal gas discharges within and outside the two sides of the rift (from 0.1 to 1.7 R/Rair). Similarly, δ13 C-CO2 ratios of the peripheral gas emissions are lighter (from -5.9% to - 11.6% VPDB) than those of the crater fumaroles. Therefore, the spatial distribution of He and C signatures in the Lake Kivu region is mainly produced by mixing of mantle-related (e.g., Nyiragongo crater fumaroles and/or mazukus gases) and crustal-related (e.g., gas discharges in the Archean craton) fluids. The CO2/He ratio (up to 10×10) is 1 order of magnitude higher than those found in MORB, and it is due to the increasing solubility of CO2 in the foiditic magma feeding the Nyiragongo volcano. However, the exceptionally high 40Ar */He ratio (up to 8.7) of the Nyiragongo crater fumaroles may be related to the difference between He and Ar solubility in the magmatic source. The results of the present investigation suggest that in this area the uprising of mantle-originated f luids seems strongly controlled by regional tectonics in relation to the geodynamic assessment of the rift. These fluids are mainly localized in a relatively small zone between Lake Kivu and Nyiragongo volcano, with important implications in terms of volcanic activity. Copyright 2010 by the American Geophysical Union
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