1,720,969 research outputs found
Crystal c-axes (fabric analyser G50) of ice core samples (vertical thin sections) collected from the polar ice core EGRIP, 118-350 m depth (2017)
No full textLarge area scan macroscope images of ice core samples (vertical thin sections) collected from the polar ice core EGRIP, 118-350 m depth (2017)
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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
Analysis of physical properties and impurities in Greenland ice using optical and Raman microscopy
No full textThe aim of this study was to determine relations between the impurity content and the microstructural features of natural ice using Raman spectroscopy. It should be investigated whether certain chemical species can be related to microstructural features, such as grain boundaries. The method of Raman spectroscopy enables to measure the particles in situ without melting the ice samples. Fourteen bags of the NEEM ice core (North Greenland Eemian Ice Drilling), drilled from different depths, were chosen.
As a first step, data from fabric analysis (mean grain size and eigenvalue 3) were plotted together with data for the major ions obtained from continuous flow analysis and correlation coefficients between those parameters were calculated. The statistically significant correlations between the chemical and physical parameters remained sporadic. For a case study, two sections from Holocene ice from a depth of 739,75 m to 740,30 m were chosen. After mapping the microstructure of the sections, particles were labelled and counted (from a layer with a focal depth of approximately 500 μm). Using Raman spectroscopy the particles were measured in-situ and the chemical species of most of the compounds could be identified. The major components were sulfate, silica particles, TiO2, some organic species and black carbon, which mostly appeared as a mixed signal. No carbonates were found and no Raman spectra could be obtained from grain boundaries or triple junctions. The particles often appeared to be in clusters or conglomerates. The location of the particles in relation to grain boundaries was difficult to assess due to relaxation of the ice
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
Physikalische Eigenschaften und Spurenstoffe im grönländischen Eis - Korrelationsberechnungen zwischen Korngröße bzw. Eigenwert und Spurenstoffkonzentrationen an ausgewählten Stücken des NEEM-Eiskerns -
No full textPredicting future climate requires deep understanding of past climatic processes. Deep ice cores drilled in Greenland and Antarctica provide an excellent archive for climate proxies, which can be extracted by several methods.
Flow properties of ice sheets can be derived by measuring c-axes orientations; furthermore trace elements and impurities can help to reconstruct atmospheric circulation patterns and provide information about the paleo-temperature. It is assumed that the impurity content of the ice does influence the grain size as well as c-axes orientations.
The aim of this thesis is to investigate the relations between impurities and ice microstructure statistically. This was done by calculating correlations (Pearson and Spearman) and cross-correlations between mean grain sizes, c-axes orientations and chemical components. The data for the calculations was taken from four bags of the NEEM ice core (North Greenland Eemian Ice Drilling), drilled at depths of approximately 1845 m to 2202 m.
The correlation coefficients showed only very weak statistical relations between the parameters. However, during preparation and measurement of the samples as well as during processing of the data, several error sources could be detected, possibly causing slight distortions of the results
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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