1,721,270 research outputs found
Fluxes of largest volcanic peaks in the EDC sulfate record
No full textAn existing ice core sulfate dataset was processed to identify the largest volcanic eruption peaks of the last 203 kyr. The dataset used consisted of high resolution sulfate data (previously archived at https://www.ncdc.noaa.gov/paleo-search/study/31332), analysed by fast ion chromatography, from the EPICA Dome C ice core. To process the data, a background was removed, and fluxes of sulfate deposited were calculated for every peak above background, using a consistent method that corrects for ice accumulation rate and thinning. A threshold flux of 20 mg m⁻² yr⁻¹ has been used to ensure that only peaks of definite volcanic origin are listed. This dataset lists the depths, ages (AICC2012 age model) and fluxes of each peak with a flux > 20 mg m⁻² yr⁻¹
EDML ice-core volcanic sulfate concentration and deposition from 78.97 to 79.97 ka BP
No full textWe present continuous records of ca. 2 cm resolved sulfate concentrations using a Continuous Flow Analysis (CFA) system (Röthlisberger et al., 2000; Severi et al., 2007; Wegner et al., 2015) from the EPICA Dronning Maud Land (EDML; 75.00°S, 00.07°E; 2892 m a.s.l.) ice core and estimated volcanic sulfate mass depositions for the time period 78.97 to 79.97 ka BP on the AICC2012 chronology (Veres et al., 2013) using a common volcanic marker in EDC dated 79.51 ka BP. The reconstruction is based on sulfate measurements employing high-resolution continuous flow analysis coupled to Fast Ion Chromatography. Volcanic eruptions are detected when annual sulfur concentrations exceeded the background concentrations + 4 times the median of the absolute deviation. Background concentrations are estimated using a 101-point running median. Volcanic sulfate deposition rates are calculated by subtracting the background concentrations from total sulfate concentrations using thinning corrected estimates of mean ice accumulation rates at the ice-core site
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
Ionic impurities in superficial snow sampled in the Antarctic campaign 2019-20 along the East Antarctic International Ice Sheet Traverse (EAIIST) from Dome C to South Pole
No full textThe data set consists in the ionic composition determined by ion chromatography of the superficial snow sampled in the Antarctic Campaign 2019-20. In the framework of the "East Antarctic International Ice Sheet Traverse" (EAIIST) project, surface snow samples were collected along a traverse from Dome C (75° 06' 01'' S, 123° 20' 48'' E - East Antarctic plateau) toward the geographic South Pole during the 2019-2020 Antarctic campaign. 32 samples were collected using 50 mL tubes by personnel wearing low particulate release clothing, polyethylene gloves to minimize external contamination. The uppermost 6 cm of snow were collected by inserting the tubes into the surface snow of the sampling site upwind and at a sufficient distance from the convoy to reduce the contamination risk. The tubes were kept frozen until the analysis. The cationic (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺) and anionic (Cl⁻, NO₃⁻, SO₄²⁻) content was determined by Ion Chromatography. The reproducibility of the measurements is always better than 4% and detection limit are in the range 2-5 ug/l for anions and 0.1-0.6 ug/L for cations. Details on analytical method are reported in the paper Ventisette et al. 2023. The data set is useful to study the spatial distribution of major ions on the inner Antarctic plateau, to understand their deposition and post deposition processes in this area characterized by megadune and wind crust formation (Ventisette et al., 2023). The knowledge and quantification of these processes will allow the interpretation of the ice core stratigraphies in low snow accumulation rate
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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