1,720,956 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Chemical composition of banded iron-formations of the Griqualand West Sequence, Northern Cape Province, South Africa, in comparison with other Precambrian iron formations
No full textMesobanded lithotypes (band rhythmites) of banded iron-formation (BIF) from the Griquatown and Kuruman Iron Formations of the Asbestos Hills Subgroup (Transvaal Supergroup, South Africa) have been sampled. 142 major and trace element analyses from diamond drill cores, an underground mine and an open pit mine were carried out. Out of these 19 open pit mine samples were excluded from the interpretation of the analytical results because of a different behaviour of the alkali elements. It is shown that other published data seem to suffer from the same effect. The results show that the chemical composition of the iron-formations is virtually independent of their stratigraphic and geographic localities over hundreds of kilometres across Griqualand West, if averaged element distribution patterns are compared. The major element composition of mesobanded iron-formation samples (magnetite chert and magnetite-carbonate chert, riebeckite-carbonate chert and ironsilicate chert) varies between 30 and 51 wt.% SiO2, 23 and 66 wt.% Fe2O3T, < 0.02 and 0.14 wt.% TiO2, < 0.04 and 1.9 wt.% Al2O3, < 0.02 and 1.05 wt.% MnO, 1.48 and 7.5 wt.% MgO, 0.14 and 12.09 wt.% CaO, 0.11 and 4.26 wt.% Na2O, < 0.007 and 2.39 wt.% K2O and < 0.01 and 1.57 wt.% P2O5. The trace element contents are generally low and range from < 1 to 2 ppm Nb (detected in only one sample), < 2 to 23 ppm Zr, < 3 to 31 ppm Y, < 2 to 152 ppm Sr, < 4 to 5 ppm U (detected in only one sample), < 2 to 240 ppm Rb, < 4 to 4 ppm Th, < 4 to 19 ppm Pb, < 3 to 4 ppm Ga, < 4 to 33 ppm Zn, < 6 to 69 ppm Cu, < 7 to 17 ppm Ni (detected in only one sample), < 5 to 59 ppm Cr, < 4 to 16 ppm V and < 10 to 177 ppm Ba. The intercalated stilpnomelane lutites have a very similar gross composition but regularly display higher concentrations of Al2O3, TiO2, K2O, and Zr. They have a different origin but certainly bear the imprint of the BIF environment and must be considered a clastic contaminant of the otherwise chemically or biochemically precipitated iron-formations. Clastic contamination and subsequent hydrothermal alteration are the most plausible agents which effected the element distribution pattern of the BIF, because they are best to reconcile with a model which assumes hydrothermal fluids as major sources of BIF. It can be concluded, from the general geochemical uniformity of BIF throughout the depository and from the absence of clear-cut relations of elemental distributions and ratios to crustal components (documented by low K/Rb, high Rb/Sr ratios, no relevant correlation between TiO2 and Al2O3), that a basinward hydrothermal system acted as a source for the Fe and Si in the BIF. The geochemical similarity between the microbanded Kuruman Iron Formation and the interbedded granular and microbanded Griquatown Iron Formation suggests deposition of the iron-formations in the same chemical environment over the entire basin from the inception of these conditions until their termination by clastic input. The somewhat lower trace element concentrations in the Griquatown Iron Formation as compared to the Kuruman Iron Formation probably do not mean an environmental change, but may reflect the diagenetic and tectonic evolution of the iron-formations. Regular but short-lived interruptions by distal volcanic ash had no influence on the bulk BIF composition. On the contrary, the volcanics reveal a strong overprint by the regional major element BIF chemistry. Therefore, the relationship between volcanogenic rocks and banded iron-formation seems to be coincidental and related to basin development. The general geochemical similarity of the Griquatown and Kuruman Iron Formations with other Proterozoic and Archaean iron-formations in the world and especially with those of the Hamersley Basin, leads us to the conclusion that the BIF of the Griqualand West Sequence are representatives of typical, large-scale iron-formations of the Precambrian, which all formed in chemically very similar environments. © 1995.Articl
Carbon and oxygen isotope variations in southern African carbonatites
No full textThe C and O isotope composition of 54 carbonate samples from 18 carbonatite localities throughout southern Africa was determined. Sample frequency distributions indicate a dependence of the δ13C and δ18O values of southern African carbonatites on their carbonate mineralogy. The calcite carbonatite samples fall into the range -8‰ to -4‰ for δ13C and + 6‰ to +10‰ for δ18O, which is defined as the primary igneous carbonatite field (Taylor et al., 1967). Those samples with higher δ13C and δ18O values are either dolomite/ankerite carbonatites or contain dolomite/ ankerite, possibly indicating the involvement of different magmatic or hydrothermal phases in the carbonatite formation. Emplacement level, type of country rock intruded and secondary alteration by e.g. hydrothermal fluids, seem to be the most important parameters which affected the C and O isotope patterns found in southern African carbonatite complexes. Magmatic processes like fractional crystallisation and liquid immiscibility are of minor importance in controlling C and O isotope ratios. An alteration model of at least two stages is proposed for the evolution of the C/O isotope patterns observed in southern African carbonatites.The first stage involved magmatic-metasomatic processes during or shortly after the formation of carbonatites. These processes affected both the C and O isotope composition of carbonatites by exchange with a H2O/CO2-rich fluid and led to higher δ13C and δ18O values when compared to primary igneous values. The elevated 18O content of carbonatite carbonates was introduced by a second stage (or more stages) of post-magmatic, hydrothermal alteration and/or interaction with ground water at low (<200-250°C) temperatures. These alterations seem to be accompanied by a growing mineralogical diversity, which reflects, to some extent, the degree of alteration affecting the carbonatites. Information on stable isotope heterogeneities of the igneous sources of southern African carbonatites is obscured. Small scale C isotope heterogeneities within the igneous sources of carbonatites may be found, provided that the effects of a first stage, magmatic-metasomatic alteration can be eliminated. Changes in δ18O values of carbonatites by sub-solidus second stage alteration processes within the crust further complicate an estimation of stable isotope variations of igneous carbonatite sources. © 1997 Elsevier Science Limited.Articl
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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