1,720,982 research outputs found
Lower Jurassic conodonts from the Inuyama area of Japan: implications for conodont extinction
Full text linkIt is generally accepted that conodonts went extinct at the end of the Triassic, but younger conodont fossils have been reported, and it is becoming clear that conodont extinction occurred asynchronously across different regions. Although some reports of post-Triassic conodonts have been disproven, Lower Jurassic conodonts have been found in the Buda area of Hungary and the Inuyama area of Japan. Here, we report the discovery of more conodonts Misikella posthernsteini above the first occurrence of the typical Jurassic radiolarian Pantanellium tanuense, which is not know from the Triassic, in the Kastuyama section, Inuyama area, reaffirming the authenticity of the Lower Jurassic conodonts. The conodonts survived into the Jurassic in the Inuyama area might be due to their remote locations relative to the Central Atlantic Magmatic Province, which buffered them from hypoxia and ocean acidification. Although conodont survived into the Lower Jurassic, they failed to recover and quickly went extinct in post-extinction ecosystems. The “dead clades walking” (DCWs) of conodont may have been due to protracted ocean acidification in the earliest Jurassic. Food scarcity and competition with other organisms may have led to the eventual extinction of conodonts
Sr isotope variations in the Upper Triassic succession at Pizzo Mondello, Sicily: Constraints on the timing of the Cimmerian Orogeny
Full text linkhe Late Triassic Cimmerian Orogeny was a result of the final closure of the Palaeotethys Ocean and the ac- cretion of Gondwana-derived (Cimmerian) continents to southern Eurasia. Determining the timing of the Cimmerian Orogeny is crucial to our understanding of the large-scale climate changes driven by the uplift of the Cimmerian Mountains. Here we present stratigraphic variations in 87Sr/86Sr values of Upper Triassic pelagic limestone from the Pizzo Mondello section, Sicily, Italy, that constrain the timing of uplift of the Cimmerian Mountains. The 87Sr/86Sr values remain relatively constant in the lower part of the section, decreasing slightly in the Tuvalian (upper Carnian) and Lacian (lower Norian). However, 87Sr/86Sr ratios rise sharply at the Lacian–Alaunian (lower–middle Norian) boundary and continue to rise through to the Sevatian (upper Norian). This observation indicates an increased input of radiogenic strontium derived from continental weathering, which resulted from the rapid uplift and erosion of the Cimmerian Mountains at this time. The climatic and environmental changes following the uplift of the Cimmerian Mountains provide an explanation for (1) an intense sea-surface-temperature warming event in the western Tethys Ocean, and (2) a rapid increase in pre- cipitation on the northern coast of the Tethys during the Alaunian–Sevatian
Weathering trends in the Norian through geochemical and rock magnetic analyses from the Pignola–Abriola section (Lagonegro Basin, Italy)
Full text linkWe investigated the geochemical and rock magnetic properties of the magnetostratigraphically calibrated Pignola-Abriola section (Italy) in order to understand the climatic perturbations that characterize the late Norian-early Rhaetian interval (Late Triassic). We performed experiments on anhysteretic and isothermal remanence (ARM and IRM) and on magnetic susceptibility ( chi ) to obtain the rock magnetic parameters necessary for our paleoclimatic investigation. An episode of increase in the relative quantity of hematite, suggesting the enhanced subaerial oxidation of iron minerals, was identified in the Norian from similar to 217 Ma in the Alaunian up to similar to 211 Ma in the early Sevatian, followed by a decline up to 207-206 Ma at the end of the Norian (late Sevatian). The results of geochemical and multivariate statistical analyses support a long-term increase and reduction in rock weathering, confirming and extending previous 87 Sr / 86 Sr data from the Pizzo Mondello section (Italy). Possible causes of these long-term weathering trends are the multiphase uplifting of the Cimmerian orogen, occurring at mid-northern latitudes along the southern margin of Asia in the Late Triassic, and/or the northward motion of Pangea across the equatorial humid belt. Rapid excursions in oxidized iron minerals have also been observed across the Norian-Rhaetian boundary, the origin of which still has to be determined
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
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