1,721,029 research outputs found
Evidence for Late Devonian (Kellwasser) anoxic events in the Great Basin, western United States
Get PDFThe Frasnian-Famennian (Late Devonian) mass extinction has often been related to the development of the Kellwasser anoxic events in Europe and North Africa but the synchronous development of the anoxia has not been reported from the Great Basin of the western United States. An integrated sedimentological, palaeoecological, and pyrite petrographic study has been undertaken on a range of F-F boundary sections from Nevada and Utah spanning a spectrum of carbonate and clastic depositional environments from distal basin, base-of-slope, mid-slope, and intrashelf basin settings. These reveal a range of facies from oxic strata, fully bioturbated and lacking any pyrite, to euxinic strata characterised by fine lamination and pyrite framboid populations of small size and narrow size range. Oxygen-restricted deposition is seen in all sections at various times, but the only interval characterised by basin-wide euxinicity occurs at the end of the Frasnian Stage late in the linguiformis Zone. This is the peak of the F-F mass extinction and it is also contemporaneous with the Upper Kellwasser Horizon of Europe. The study therefore reinforces the claim that the mass extinction coincides with the global development of marine anoxia. Shallow-water sections were not studied but slope and base-of-slope sections record many sediment-gravity flows that transported an allochthonous fauna into deeper water settings. This shallow-water fauna temporarily disappears late in the linguiformis Zone perhaps indicating the development of oxygen-restriction in shallow-water settings. Intriguingly the condensed, deepest water sections from the Woodruff basin record somewhat higher oxygenation levels than the contemporaneous slope sections. The most oxygen-restricted conditions may therefore have occurred in a mid-water oxygen-minimum zone that expanded its vertical range both upwards and downwards and became sulfidic late in the linguiformis Zone
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
Sedimentology of the Triassic–Jurassic boundary beds in Pinhay Bay (Devon, SW England)
Get PDFSedimentology of the Triassic–Jurassic boundary beds in Pinhay Bay(Devon, SW England). Proceedings of the Geologists’ Association, 112. 349–360. New exposures
in Pinhay Bay (SE Devon) of the White Lias (Langport Member of the Lilstock Formation)and basal Blue Lias reveal rapidly changing palaeoenvironments during the Triassic–Jurassic(T–J) boundary interval. During deposition of the topmost White Lias a soft seafloor of micritic mudstone was lithified and bored. The resultant hardground was locally eroded, probably in a
shallow marine setting, to form a spectacular intraformational conglomerate that was itself lithified. Brief subaerial emergence then followed and produced a fissured and pitted top surface to the White Lias. The regression was short lived and rapid transgression at the base of the Blue Lias established organic-rich shale deposition with a small framboidal pyrite population and
low Th/U ratios indicative of a stable, sulphidic lower water column (euxinic conditions). The White Lias/Blue Lias contact thus records a short duration, high amplitude relative sea-level change. This sea-level oscillation has also been postulated for other T–J boundary sections in
Europe, although the failure to identify it in regional-scale sequence stratigraphic studies is probably due to its brief duration. Deposition of the basal beds of the Blue Lias was marked by a discrete phase of syn-sedimentary folding and small growth fault activity that may record a regional pulse of extensional tectonic activity
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
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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