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Notes on the rare Cretaceous species Syndetocystis uralensis Strelnikova leading to the description of a new monotypic genus Monoportula P.A.Sims et D.M.Williams nov. gen.
No full textWilliams, David M., Sims, Pat A., Witkowski, Jakub (2023): Notes on the rare Cretaceous species Syndetocystis uralensis Strelnikova leading to the description of a new monotypic genus Monoportula P.A.Sims et D.M.Williams nov. gen. Phytotaxa 595 (2): 219-224, DOI: 10.11646/phytotaxa.595.2.8, URL: http://dx.doi.org/10.11646/phytotaxa.595.2.
FIGURES 9–12. 9 in Notes on the diatom collection of the Natural History Museum, London (BM) V: (a) 'Stictodiscus manillensis' nom. nud., (b) Stictodiscus pantocsekii and 'Stictodiscus pantocsekii var. minor', (c) a note on the name 'Stictodiscella'; and (d) some comments on Jósef Pantocsek's Beiträge zur Kenntnis der Fossilen Bacillarien
No full textFIGURES 9–12. 9. Stictodiscus pantocsekii after Tempère (in Brun et al. 1890: pl. 4, fig. 6, see Fig. 9). 10. Drawing of Stictodiscus pantocsekii from Pantocsek (1892: pl. II, fig. 31). 11. Stictodiscus pantocsekii, BM 52932. 12. 'Stictodiscus pantocsekii var. minor', BM Adams GC 2839, holotype, 'Mt. Hillaby, nov.', Chimborazo, Barbadoes. Scale bars = 20 μm.Published as part of Williams, David M., Sims, Pat A. & Witkowski, Jakub, 2021, Notes on the diatom collection of the Natural History Museum, London (BM) V: (a) 'Stictodiscus manillensis' nom. nud., (b) Stictodiscus pantocsekii and 'Stictodiscus pantocsekii var. minor', (c) a note on the name 'Stictodiscella'; and (d) some comments on Jósef Pantocsek's Beiträge zur Kenntnis der Fossilen Bacillarien, pp. 167-174 in Phytotaxa 507 (2) on page 171, DOI: 10.11646/phytotaxa.507.2.4, http://zenodo.org/record/542561
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
Stictodiscus manilensis D. M. Williams, P. A. Sims, & J. Witkowski 2021, sp. nov.
No full text<i>Stictodiscus manilensis</i> D.M.Williams, P.A.Sims, & J.Witkowski, <i>sp. nov.</i> <p> <b>Type:—</b> Philippines: Manila (‘ Manilla’), (holotype BM Adams F 1148 = Fig. 1, one specimen); BM 5473 (Deby, one specimen), BM 7431 (Deby, one specimen), BM 8865 (Deby, ‘ Manilla’ = Fig. 3, one specimen), BM 10652 (Deby, L.H. 826, two specimens), BM 45641 (Sturt, A578, three specimens), BM 45863 (Sturt A800, one specimen). Singapore: BM 10435 (Deby, L.H. 547, one specimen).</p> <p>Valves circular with flat valve face; mantle distinctive. Valve with small central annulus, radiating network of ‘siliceous bars’ leading to areolae, mostly biseriate. Raised siliceous thickenings surround series of radiating inner areolae, becoming more conspicuous towards valve mantle. No other surface structures.</p>Published as part of <i>Williams, David M., Sims, Pat A. & Witkowski, Jakub, 2021, Notes on the diatom collection of the Natural History Museum, London (BM) V: (a) ' Stictodiscus manillensis' nom. nud., (b) Stictodiscus pantocsekii and ' Stictodiscus pantocsekii var. minor', (c) a note on the name ' Stictodiscella'; and (d) some comments on Jósef Pantocsek's Beiträge zur Kenntnis der Fossilen Bacillarien, pp. 167-174 in Phytotaxa 507 (2)</i> on page 169, DOI: 10.11646/phytotaxa.507.2.4, <a href="http://zenodo.org/record/5425611">http://zenodo.org/record/5425611</a>
Monoportula P. A. Sims & D. M. Williams, nov. gen.
No full text<i>Monoportula</i> P.A.Sims & D.M.Williams nov. gen. <p> <b>Registration</b>: http://phycobank.org/103661</p> <p> Type species:— <i>Monoportula uralensis</i> (Strelnikova) P.A.Sims & D.M.Williams nov. comb.</p> <p>Frustules cylindrical, valve face circular, flat. Valve face bordered by expanded marginal ridge separating it from vertical mantle. Areolae poroid, on valve face arranged in interrupted radial and sub-radial rows extending from off-centre hyaline area from which a stout spine extends. Scattered spinules cover valve face disturbing areolar arrangement. Mantle areolae in vertical rows situated between hyaline marginal ridge and hyaline valve margin. Mantle areolae covered by network of anastomosing costae. Internally areolae sunk in rows between hyaline ribs, areolae becoming more numerous towards valve margin. One (1) rimoportula present, its external opening through stout tube expanded at its summit, internally as slit between raised lips.</p>Published as part of <i>Williams, David M., Sims, Pat A. & Witkowski, Jakub, 2023, Notes on the rare Cretaceous species Syndetocystis uralensis Strelnikova leading to the description of a new monotypic genus Monoportula P. A. Sims et D. M. Williams nov. gen., pp. 219-224 in Phytotaxa 595 (2)</i> on page 220, DOI: 10.11646/phytotaxa.595.2.8, <a href="http://zenodo.org/record/7905940">http://zenodo.org/record/7905940</a>
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
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