1,720,956 research outputs found
TAXONOMY AND EVOLUTIONARY RELATIONSHIPS WITHIN THE CALCAREOUS NANNOFOSSIL GENUS <em>ERICSONIA</em> IN THE UPPER PALEOCENE
Full text linkDetailed distribution ranges of the genus Ericsonia were obtained in the upper Paleocene interval from two deep-sea sections, ODP Site 1262 (South Eastern Atlantic Ocean) and Site 1215 (Eastern Equatorial Pacific Ocean), and were complemented with morphometric analyses with the purpose of clarifying the taxonomy of the Paleocene species ascribed to genus. The analysis on a high-resolution sampling set at ODP Site 1262 permitted to add information about the evolutionary relationship among the taxa included in the Ericsonia lineage, whose evolutionary emergence characterize the Paleocene nannofossil assemblages. Two taxonomic units have been validated in the Paleocene, Ericsonia subpertusa and Ericsonia robusta and they turned out to not have any evolutionary link. E. robusta shows substantial morphologic variability at cross-polarized light resulting in two endmember morphotypes, E. robusta morphotype A and E. robusta morphotype B. When observed at S.E.M., the two morphotypes have placoliths with a similar structure, therefore they document intra-specific variability. This is corroborated by the presence of specimens with intermediate morphologic features between the two endmembers, throughout the distribution range. E. robusta increases in abundance concomitantly with the sharp decline of E. subpertusa in mid Chron C25n. Subsequently, the highest occurrence of E. robusta morphotype B provides a distinct biohorizon coeval to the general decline of E. robusta within the upper Paleocene nannofossil assemblage
Calcareous nannofossils as a dating tool in shallow marine environment. An example from an upper Paleogene carbonate platform succession in the Mediterranean
No full textIn this study, calcareous nannofossils have been used for refining the biostratigraphic classification and chronology of a neritic Paleogene sedimentary succession, outcropping in the Central Apennines (Italy) and belonging to the Santo Spirito Formation". Calcareous nannofossils are typically found in deep-sea sediments, but proved to be consistently present and useful also in these shallow -water deposits. The obtained biostratigraphic results benefitted from the random occurrence of rich and diversified nannofossil assemblages in chalky sediments, found inside chert nodules and as thin layers, within the dominant calcarenitic lithology of this lithostratigraphic unit. The observed well-preserved assemblages provided a reliable biostratigraphic framework that was completed with the analysis of intervening samples obtained from scattered layers of calcareous marls. In the two studied sections, Pennapiedimonte and Lettomanoppello sections, we recognize a series of biozones that integrate with the known biostratigraphy based on large and planktonic foraminifera. Overall, we provide a reliable chronology indicating that the stratigraphic succession of Santo Spirito Fm, in the investigated area, is constrained between similar to 42 Ma (late Lutetian) and similar to 31 Ma (early Rupelian). This precise strati graphic assignment extends of similar to 2 m.y. the time lapse of sedimentation of the middle and upper Santo Spirito Fm, previously considered in these sections as limited to upper Bartonian-lower Rupelian. The obtained more accurate chronology is helpful for an ongoing study addressed to perform a detailed sequence stratigraphic interpretation of the unit, specifically to recognize higher rank depositional sequences within it. Moreover, our data evidence that the Eocene/Oligocene transition, with the intervening large transient glaciation event "Oi-1, is represented in the sediments of S. Spirito Fm, suggesting that further studies in this area could provide new information on the response of this global climatic event in shallow -water marginal environments
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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