1,720,998 research outputs found
A review of basin-wide calcareous nannofossil bioevents in the Mediterranean at the onset of the Messinian salinity crisis
Full text linkDuring the Messinian (7.2–5.3 Ma) the Mediterranean area experienced fast and deep climatic and eustatic
structural changes. The stratigraphic framework for this interval is relatively well constrained and the beginning
of the Messinian salinity crisis (MSC) dated at 5.971 Ma suggests a duration of at least 1.2 Ma for the preevaporitic Messinian that is the object of this study.
A number of sites (Faneromeni, Pissouri, Polemi Basin, Kalamaki, Falconara, Fanantello, Lemme, Pollenzo,
Govone, Moncalvo: Blanc-Valleron et al., 2002; Wade and Bown, 2006, Kouwenhoven et al., 2006; Morigi et al.,
2007; Lozar et al., 2010, 2018; Dela Pierre et al., 2011, Karakitsios et al., 2017) show similar behaviour of the
calcareous nannofossil record where several peaks of Sphenolithus spp. are recognised at different levels in each
of the section.
This paper compares the calcareous nannofossil data from six different sections across the Northern and
Eastern Mediterranean area encompassing the onset of the MSC.
Interestingly, a tight succession of bioevents (Sphenolithus abies, Helicosphaera carteri, Umbilicosphaera rotula,
Rhabdosphaera spp.) is recorded in all the sections analysed and appears to correlate precisely among the investigated sites, approximating the onset of the Messinian salinity crisis, thus offering the possibility to use these
as bioevents for regional correlation
Orbital tuning of a Lower Cretaceous composite record (Maiolica Formation - Central Italy)
No full text
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
Microfossil assemblages of Zanclean diatomaceous silts from the Monferrato (Piedmont, Northwestern Italy): new paleoenvironmental data
No full textDispelling 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
Eocene calcareous nannofossils from southern Tibet: Paleoceanographic implications for the closure of the eastern Tethys Ocean
No full textThe India-Asia collision led to the demise of the Tethys Ocean, and the subsequent uplift of the Qinghai-Tibet Plateau had a profound impact on Cenozoic topography, oceanography, and climate. However, collision ages vary depending on collision definition and methodology, with the cessation of marine deposition constraining the minimum/youngest collision age. The Enba and Zhaguo formations of the Qumiba Section (southern Tibet) represent the youngest marine strata in the eastern Tethys Ocean. Previous studies have suggested a middle-late Eocene or early Eocene closure time, however, our nannofossil data indicate an age of 53.67–52.64 Ma (nannofossil zone CNE3, which closely corresponds to Zone NP11). Nannofossil relative abundances can explain the early Eocene tectonic evolution of southern Tibet, with the increasing number of reworked Cretaceous nannofossils over time reflecting the degree of erosion of previously deposited sediments as the plateau uplift progressed. Our data suggest that Cretaceous and Paleocene calcareous nannofossils were an important sediment source to the Qumiba Section
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