1,720,977 research outputs found
Reinterpretation of the dinoflagellate Glenodinium sanguineum in the reddening of Lake Tovel, Italian Alps
No full textLake Tovel in the Italian Alps is famous for its blood-red water during summer, caused by a dinoflagellate named Glenodinium sanguineum. The red colour has been largely absent since 1964 and a project aimed at understanding the underlying cause of the colour change was begun in 2000. It appears that there are three dinoflagellates in the lake that morphologically somewhat resemble ‘G. sanguineum’. One of these agrees with the ‘red form’ of G. sanguineum studied in the detailed work of Baldi (1941), and is now very scarce in the plankton. The other agrees with Baldi's ‘green form’ and now dominates the plankton. Transmission electron microscopy has demonstrated that the third taxon is identical to what Dodge et al. (1987) identified as G. sanguineum from Lake Tovel. It did not develop a red colour under any of the growth conditions used in our experiments. The red form is very similar to Woloszynskia coronata, but differs in cyst morphology. It is shown that the red and green forms of G. sanguineum sensu Baldi are clearly distinct species. Reduction in nutrient loads entering the lake subsequent to changes in animal husbandry practices in the lake's catchment occurred around 1964. This apparently tipped the balance between the three species of dinoflagellates, resulting in the near disappearance of the red form from the plankton and concomitant disappearance of the red colour from the lake
Studies on woloszynskioid dinoflagellates II: on Tovellia sanguinea sp. nov., the dinoflagellate responsible for the reddening of Lake Tovel, N. Italy
No full textplankton, alger, Tovel, dinoflagellaterAbstract The organism responsible for the former annual reddening of Lake Tovel in the Italian Alps (up to 1964) has been identified and studied in detail. Considerable confusion exists regarding the identity of this organism, and the detailed description by Baldi in 1941 is now believed to be based on more than one organism. Baldi's red and green forms appear to be two different organisms, both of which have now been isolated into unialgal culture and studied using light microscopy, electron microscopy, and sequencing of the large subunit of ribosomal DNA (LSU rDNA). The organism has been found in three lakes in the area, but only in Lake Tovel have conditions allowed for reddening of the water during summer. The name of the organism believed to be the cause of the reddening, Glenodinium sanguineum Marchesoni, used in numerous publications, is an illegitimate homonym of G. sanguineum H.J. Carter, and the organism is described here as a new species, Tovellia sanguinea sp. nov., the seventh species of the newly described genus Tovellia. T. sanguinea is closely related to the other red-coloured species of Tovellia, Tovellia coronata (previously known as Woloszynskia coronata) but differs in several morphological features, notably the chloroplast arrangement, and in LSU rDNA sequence divergence (11-12%). Cells preserved from Lake Tovel during a reddening phenomenon in 1938 have been re-examined by scanning electron microscopy and agree morphologically with the new isolates. Tovellia sanguinea is a species of oligotrophic or mesotrophic-oligotrophic cold-water lakes, in which the average summer temperature does not exceed 15°C. It occurs on both calcareous (as in Lake Tovel) and non-calcareous substrata (as in the other two lakes). </table
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
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
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