1,721,167 research outputs found
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
Anomalie morfologiche nei foraminiferi bentonici e stato di salute degli ambienti di transizione e marino costieri: casi di studio della laguna di Venezia e dal medio Adriatico
No full textCretaceous oceanic anoxic events and radially elongated chambered planktonic foraminifera: Paleoecological and paleoceanographic implications
No full textChamber elongation is a recurring morphological character in Cretaceous and Cenozoic planktonic foraminiferal evolution suggesting that the clavate body-plan takes advantage through particular environmental conditions. Cretaceous planktonic foraminifera bearing radially elongated chambers become repeatedly a consistent component of assemblages in correspondence with the deposition of remarkable organic layers that record the effects of oceanic anoxic events (OAEs). Due to this apparent
correspondence, chamber elongation has been recently interpreted as an adaptation to low oxygen levels in the upper water column. The paleoceanographic significance of planktonic foraminifera with radially elongated chambers remains however unclear. We investigated in great detail the distribution and abundance of elongated chambered planktonic foraminifera in an interval of about 40 myr across the Cretaceous OAEs in different well-dated sections. The increased abundance of planktonic foraminifera with elongated chambers can be a markedly evident feature across the Faraoni, the Selli and the Bonarelli OAEs. However each
event shows its own peculiarities. Remarkably, the first radiation of the Cretaceous elongated chambered morphotypes just predates the latest Hauterivian Faraoni Event. The Selli Event records the greatest diversification (number of species) of the group bearing elongated chambers. However, this was a period of great diversification in the planktonic foraminifera. This evidence may suggest that radiation of these forms was driven by more than upper water column anoxia per se (e.g., increased upper water column stratification, greater productivity, and/or greater seasonality).
The Albian OAE1b, OAE1c, and OAE1d display the lowest abundance and diversity of this group. Conversely, according to the available data, the first appearances of the species Muricohedbergella simplex and of the genus Schackoina occur close to the OAE1b and OAE1d, respectively. In the Italian record, the relative abundance of radially elongated chambered forms appears to be larger before the onset of the Bonarelli Event with respect to the Selli Event. The pattern involving this group across the Bonarelli Event appears more regular, thus indicating that the onset and the end of the OAE2 depend on very powerful global factors and are
less influenced by local aspects. We speculate that the relative abundance of planktonic foraminifera with radially elongated chambers may be proportional to the strength of the environmental perturbation related to the OAEs, thus reinforcing the idea that the ecological perturbation related to the OAE2 was more severe for the former.
Several lines of evidence suggest that water oxygenation could not have been the single controlling factor governing the development of elongate chambers. The role of availability of food and the nature of food has been so far probably underestimated. It is most likely that an interplay of several influential physical–chemical and ecological factors (i.e., dissolved oxygen concentration, temperature, salinity, nutrients, type of food, trace elements) was responsible for such a morphological adaptation.
We document linkages between the distribution, abundance, morphometric changes and evolution of the Cretaceous radially elongated chambered planktonic foraminifera and the major igneous, geological, geochemical, climate, nutrification and bioticevents and biocalcification trends
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
Cretaceous Oceanic Anoxic Events and the Radiation of Radially Elongated Chambered Planktonic Foraminifera.
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Evolutionary and paleoecological response of Cretaceous radially Elongated chambered planktonic foraminifera to the major global changes
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