1,721,026 research outputs found
A review of past and recent research on Cretaceous silicoflagellates
No full textMcCARTNEY, KEVIN (2013): A review of past and recent research on Cretaceous silicoflagellates. Phytotaxa 127 (1): 190-200, DOI: 10.11646/phytotaxa.127.1.18, URL: http://dx.doi.org/10.11646/phytotaxa.127.1.1
FIGURES 1–8 in A review of past and recent research on Cretaceous silicoflagellates
No full textFIGURES 1–8: Original illustrations for important silicoflagellate taxa to 1959. Fig. 1. Corbisema geometrica, Hanna (1928). Fig. 2. Dictyocha quadralta Hanna (1928); placed in Arctyocha by Bukry (1985). Fig. 3. Vallacerta hortoni Hanna (1928); now usually called V. hortonii. Fig. 4. Lyramula simplex Hanna (1928). Fig. 5. Lyramula furcula Hanna (1928). Fig. 6. Cornua trifurcata Schulz (1928). Fig. 7. Cornua aculeifera Deflandre (1944); placed in Variramus by McCartney et al. (1990). Fig. 8. Cornua poretzkajae Glezer (1959).Published as part of McCARTNEY, KEVIN, 2013, A review of past and recent research on Cretaceous silicoflagellates, pp. 190-200 in Phytotaxa 127 (1) on page 192, DOI: 10.11646/phytotaxa.127.1.18, http://zenodo.org/record/508540
FIGURES 9–16 in A review of past and recent research on Cretaceous silicoflagellates
No full textFIGURES 9–16: Recently discovered or photographed Cretaceous silicoflagellates. Fig. 9. Modern photograph of Cornua trifurcata, Til'tim XI locality (see Witkowski et al, 2012). Fig. 10. Arctyocha mesocena, sample C-8606, Horton River, Canada. Fig. 11. Schulzyocha loperi, ODP 113-693B-19X-4, 77–78 cm. Fig. 12. Schulzyocha ruppelii, EF0103, Devon Island, Canada. Fig. 13. Schulzyocha lurveyi, EF0102, Devon Island, Canada. Fig. 14. Umpiocha umpiana, EF0401, Devon Island, Canada. Fig. 15. Umpiocha jeletskyi EF0401, Devon Island, Canada. Fig. 16. Umpiocha jeletzskyi, EF0401, Devon Island, Canada. Fig. 17. Cornua tapiae, EF0401, Devon Island, Canada. Variramus wisei, ODP 113-693B-19X-4, 77–78 cm.Published as part of McCARTNEY, KEVIN, 2013, A review of past and recent research on Cretaceous silicoflagellates, pp. 190-200 in Phytotaxa 127 (1) on page 194, DOI: 10.11646/phytotaxa.127.1.18, http://zenodo.org/record/508540
Enhanced siliceous plankton productivity in response to middle Eocene warming at Southern Ocean ODP Sites 748 and 749
No full textThe Middle Eocene Climatic Optimum (MECO) is a major transient warming event that occurred at ~ 40 Ma and reversed a long-term cooling trend through the early and middle Eocene. We report the results of a high-resolution, quantitative study of siliceous microfossils at Ocean Drilling Program Sites 748 and 749 (Southern Kerguelen Plateau, Southern Ocean, ~ 58°S) across a ~ 1.4 myr interval spanning the MECO event. At both sites, a significant increase in biosiliceous sedimentation is associated with the MECO event. Rich siliceous planktonic microfossil assemblages in this interval are unusual in that they are dominated by ebridians, with radiolarians as a secondary major component. Silicoflagellates and diatoms comprise only a minor fraction of the assemblage, in contrast to siliceous microfossil assemblages that characterize modern Southern Ocean sediments. Based on our new siliceous microfossil records, we interpret two ~ 300 kyr periods of elevated nutrient availability in Southern Ocean surface waters which span the peak warming interval of the MECO and the post-MECO cooling interval. A diverse assemblage of large silicoflagellates belonging to the Dictyocha grandis plexus is linked to the rapid rise in sea-surface temperatures immediately prior to peak warmth, and a pronounced turnover is observed in both ebridian and silicoflagellate assemblages at the onset of peak warming. The interval of peak warmth is also characterized by high abundance of cosmopolitan ebridians (e.g., Ammodochium spp.) and silicoflagellates (e.g., Naviculopsis spp.), and increased abundance of tropical and subtropical diatom genera (e.g., Asterolampra and Azpeitia). These observations confirm the relative pattern of temperature change interpreted from geochemical proxy data at multiple Southern Ocean sites. Furthermore, rapid assemblage changes in both autotrophic and heterotrophic siliceous microfossil groups indicate a reorganization of Southern Ocean plankton communities in response to greenhouse warming during the MECO event
Fig. 13 in A new species of Cryptomonas (Cryptophyceae) from the Western Urals (Russia)
No full textFig. 13. Bayesian phylogenetic tree of the partial small subunit rDNA (SSU rDNA) and large subunit ribosomal DNA (LSU rDNA) combined data set. The Bayesian posterior probability (left) and maximum likelihood bootstrap value (right) are shown. Scale bar represents estimated number of substitution per site.Published as part of Martynenko, Nikita A., Gusev, Evgeniy S., Kulizin, Pavel V., Guseva, Elena E., McCartney, Kevin & Kulikovskiy, Maxim S., 2020, A new species of Cryptomonas (Cryptophyceae) from the Western Urals (Russia), pp. 1-12 in European Journal of Taxonomy 649 on page 7, DOI: 10.5852/ejt.2020.649, http://zenodo.org/record/383610
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
(Table 5) Relative abundance of Pliocene and Pleistocene sponge spicules from ODP Hole 113-695A
No full textX = present, - = absent, the occurrence of "actino"- specimens are designated by "a"
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