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Valve Ultrastructure and Description of a new Luticola D.G.Mann (Bacillariophyceae) species from Colorado, USA
No full textShea, Rachel, Greifenstein, Jeremy, Kociolek, J.P. (2022): Valve Ultrastructure and Description of a new Luticola D.G.Mann (Bacillariophyceae) species from Colorado, USA. Phytotaxa 554 (3): 269-277, DOI: 10.11646/phytotaxa.554.3.
FIGURES 9–11 in Valve Ultrastructure and Description of a new Luticola D.G.Mann (Bacillariophyceae) species from Colorado, USA
No full textFIGURES 9–11. Luticola coloradiana, sp. nov. Scanning electron microscopy. External valve views. Figures 9–11. Valves demonstrate rugose nature of the valve face. Striae appear interrupted longitudinally. Proximal raphe ends are deflected towards the same side; stigma opening is positioned on the opposite side. In figures 10 and 11, the margin of the valves has an elevated ridge. In figure 11 the mantle of the valve has a series of elongated areolae. Scale bars = 5 µm.Published as part of Shea, Rachel, Greifenstein, Jeremy & Kociolek, J.P., 2022, Valve Ultrastructure and Description of a new Luticola D.G.Mann (Bacillariophyceae) species from Colorado, USA, pp. 269-277 in Phytotaxa 554 (3) on page 272, DOI: 10.11646/phytotaxa.554.3.5, http://zenodo.org/record/683156
FIGURES 12–15 in Valve Ultrastructure and Description of a new Luticola D.G.Mann (Bacillariophyceae) species from Colorado, USA
No full textFIGURES 12–15. Luticola coloradiana, sp. nov. Scanning electron microscopy. External views. Fig. 12. Central area with deflected external proximal raphe ends. Arrow indicates stigma opening. Scale bar = 1.5 µm. Fig. 13. Showing many depressions in the central area, many of which also have very small, rounded granules. Scale bar = 1.5 µm. Fig. 14. External distal raphe end is hooked and extends onto the mantle. Scale bar = 1.0 µm. Fig. 15. Girdle view of the end of the valve. Elevated ridge around the margin of the valve is evident. There is a row of elongated areolae which have a row of smaller areolae positioned towards the valve. Cingulum elements have a row of poroids. Scale bar = 2.5 µm.Published as part of Shea, Rachel, Greifenstein, Jeremy & Kociolek, J.P., 2022, Valve Ultrastructure and Description of a new Luticola D.G.Mann (Bacillariophyceae) species from Colorado, USA, pp. 269-277 in Phytotaxa 554 (3) on page 273, DOI: 10.11646/phytotaxa.554.3.5, http://zenodo.org/record/683156
Luticola coloradiana Shea, Greifenstein & Kociolek 2022, sp. nov.
No full textLuticola coloradiana, Shea, Greifenstein & Kociolek, sp. nov. (Figs 1–19) Description: In LM (Figs 1–8) valves are rhombic-lanceolate to rhombic in smaller specimens. Valves measure 23.0– 70.0 µm in length, 11.0–18.5 µm in breadth. Raphe branches are axial, along the apical axis. Isolated stigma near center of valve. Striae radiate outwards, non-uniform in appearance, often becoming smaller close to valve margin, 10–12 in 10 µm. In the SEM, the valve exterior has a rugose appearance, formed by thickened ridges running longitudinally along the apical axis of the valve and by areolae being located in depressions on the valve face (Figs 9–11). Areola density 11–14 / 10 µm. There is an elevated ridge running around the entire margin of the valve (Fig. 11). The axial area is straight, expanded slightly towards the central area, rectangular in shape and without areolae, only a single, small stigma opening (Figs 9–13). The stigma opening is smaller than the areolae. The central area may also bear numerous small depressions that do not penetrate the valve (Fig. 13). The areolar depressions and the smaller, more shallow ones around the central area may have small granules in and around them. The raphe is straight, with proximal ends bent to one side (opposite the stigma) and distal ends bent in the same direction, opposite the direction of the proximal ends. The raphe slit is bordered by a thin rim of silica (Figs 9–11, 12, 14). The mantle of the valve has a row of small poroids and a row of prominent, elongated poroids (Fig. 15). Girdle bands number 4–5 / valve and have a single row of poroids situated towards the valve. The valve interior has an expanded axial area that is developed into a central area formed by a stauros that extends nearly to the margin (Figs 16, 17). Areolae do not appear occluded internally (Fig. 16). Proximal raphe ends terminate at the base of the central area (Figs 16–18) while the distal ends terminate in small helictoglossae (Fig. 19). On one side of the central area is the stigma opening. The stigma opening is simple, round, with a short, thickened collar (Figs 16–18). Areolae are round to dash-like in shape. The valve interior, like the exterior, appears rugose (Figs 16, 17). Thick siliceous ribs extend from the margin, and on the valve face there is a line of thin, fimbriate siliceous structures that are aligned with the ribs (Figs 16, 17). Type: — USA. Colorado, Gunnison County. Unnamed wet meadow in Gunnison County, Colorado, USA. Latitude: 38.25025126, Longitude: -107.497408. Collection was made on August 2, 2021. Holotype Slide: JPK Collection (COLO!) 651052 Isotypes: To be deposited at Academy of Natural Sciences (Philadelphia) and the Natural History Museum (London). Etymology: —Named for the state of Colorado in which it occurs. Ecology: —While no other data on the physical and chemical characteristics of the collecting site were obtained, the associated diatom flora is diverse, with unnamed species of Aulacoseira Thwaites and Encyonopsis Krammer, as well as Cavinula davisiae Bahls (2013: 15) and several species of cymbelloid diatoms being present.Published as part of Shea, Rachel, Greifenstein, Jeremy & Kociolek, J. P., 2022, Valve Ultrastructure and Description of a new Luticola D. G. Mann (Bacillariophyceae) species from Colorado, USA, pp. 269-277 in Phytotaxa 554 (3) on pages 270-273, DOI: 10.11646/phytotaxa.554.3.5, http://zenodo.org/record/683156
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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