186,198 research outputs found
Elliptochloris philistinensis Novis & Visnovsky 2012, sp. nov.
No full text<i>Elliptochloris philistinensis</i> Novis & Visnovsky, <i>sp. nov.</i> (Figs 6A–B) <p> <i>Cellulae juvenes cylindrico-ellipsoidales, 6.2–7.7 µm longae, 3.1–4.6 µm latae, aetate ellipsoideae vel sphaericae, usque ad 8.5 µm latae, unicae vel in greges aggregatae, cytoplasma vesiculis tribus vel pluribus instructa (ut videtur materiam lipidicam includentibus) continentes. Paries cellularis tenuis laevisque. Chloroplastus viridis, parietalis, cupulatus, pyrenoidem unicam per vagina valde segmentata amylacea circumdatam continens. Matrix pyrenoidis thylacoidibus pluribus penetrata sed forma non distincta. Autosporis 2–4 per sporangium regenerans.</i></p> <p> <b>Type:—</b> NEW ZEALAND: Westland: Mt Philistine, 1400 m, preserved cultured specimen from sample collected 30 November 2007, CHR610490.</p> <p> Young cells cylindrical–ellipsoidal, 6.2–7.7 µm long, 3.1–4.6 µm wide, becoming ellipsoidal to spherical with age, up to 8.5 µm wide, singly or in groups, containing 3–numerous vesicles in cytoplasm (thought to contain lipid; Fig. 5A). Cell wall thin and smooth. Chloroplast green, parietal, cup-shaped, with single pyrenoid surrounded by highly segmented starch sheath (Fig. 5B). Pyrenoid matrix penetrated by several thylakoids, but pattern indistinct. Reproduction by autospores, 2–4 per sporangium. Sequence data for the 18S rDNA gene placed <i>E. philistinensis</i> robustly in a clade of <i>Elliptochloris</i> species, but separated from others by a moderately long branch emerging at the first node (Fig. 8).</p> <p> <b>Habitat:—</b> Alpine herbfield soil.</p> <p> <b>Distribution:—</b> New Zealand.</p> <p> <b>Etymology:—</b> Referring to Mt Philistine, the site of collection.</p> <p> <b>Observations:—</b> <i>Elliptochloris</i> represents a well-defined genus in the Trebouxiophyceae. The pyrenoid of <i>E. marina</i> Letsch <i>et al.</i> 2009 is described as a “thylakoid free region” in the chloroplast, and appears similar to our observations. One other species, <i>E. subsphaerica</i> (Reisigl) Ettl & Gärtner (1995) has a pyrenoid, but this is clearly distinguished from <i>E. philistinensis</i> by young cells that are frequently curved, and by molecular data (Fig. 8).</p> <p> <b>Cultures:—</b> LCR-CG5.</p>Published as part of <i>Novis, Phil M. & Visnovsky, Gabriel, 2012, Novel alpine algae from New Zealand: Chlorophyta, pp. 1-30 in Phytotaxa 39</i> on pages 24-25, DOI: 10.11646/phytotaxa.39.1.1, <a href="http://zenodo.org/record/4894684">http://zenodo.org/record/4894684</a>
Schizochlamydella orbicularis Novis & Visnovsky 2012, sp. nov.
No full text<i>Schizochlamydella orbicularis</i> Novis & Visnovsky, <i>sp. nov.</i> (Figs 4D–E) <p> <i>Cellulae sphaericae vel subsphaericae, 3.1–6.1 µm latae. Paries cellularis tenuis laevisque. Chloroplastus viridis, parietalis, lobatus, in cellulis valentibus incisuris 2–4 instructus. Pyrenoides nulla. Cellulae coloniales, mucilaginae maturae per matricem mucilaginis achromaticam instratosam uniformiter aequidistantes. Autosporis 2–4–8 per sporangium regenerans, eae per expansionem matricis gradatim separantes.</i></p> <p> <b>Type:—</b> NEW ZEALAND: Westland: Mt Philistine, 1400 m, preserved cultured specimen from sample collected 30 November 2007, CHR610488.</p> <p> Cells colonial, spherical or near-spherical, 3.1–6.1 µm wide. Cell wall thin and smooth. Chloroplast green, parietal, lobed, with 2–4 incisions in healthy cells. Pyrenoid absent (Fig. 4E). Colonies mucilaginous, mature cells spaced evenly through colourless, unlayered mucilage matrix (Fig. 4A). Reproduction by autospores, 2–4–8 per sporangium, gradually separating through expansion of mucilage matrix (Fig. 4A). Sequence data for both the <i>rbc</i> L and 18S rDNA genes suggested that the species formed a novel lineage in the Trebouxiophyceae, with no clear affinities (Figs 8, 9).</p> <p> <b>Habitat:—</b> Alpine herbfield soil.</p> <p> <b>Distribution:—</b> New Zealand.</p> <p> <b>Etymology:—</b> “Spherical shaped”, referring to the cell.</p> <p> <b>Observations:—</b> The morphology of this species—mucilaginous colonies, lack of pyrenoids and zoospores—suggests an affinity with <i>Coccomyxa</i>, yet <i>S. orbicularis</i> is clearly a distant relative of species in the <i>Coccomyxa</i> clades. More discussion of these clades is given in remarks on <i>Pseudococcomyxa simplex</i> (below). The colonial mucilaginous habit lacking zoospores accords with the Radiococcaceae <i>sensu</i> Ettl & Gärtner (1995). Of the genera therein, the New Zealand strain most closely matches <i>Schizochlamydella</i> Korshikov (1953), with cells irregularly dispersed in homogeneous mucilage. Only one other species of <i>Schizochlamydella</i> lacks a pyrenoid, namely <i>S. minutissima</i> Broady (1982). However, this species is slightly smaller than our strain, with ellipsoidal juvenile cells. One species has previously received attention at the molecular level (Wolf <i>et al.</i> 2003): <i>Schizochlamydella capsulata</i> (Watanabe 1977). This strain is distinguished from our material by containing one or more pyrenoids, and is placed in the Oocystaceae using 18S rDNA sequences (Wolf <i>et al.</i> 2003), not closely related to <i>S. orbicularis</i> (Fig. 8). Given the paucity of characters available to classify these species, it is not surprising that morphology does not reflect phylogeny. Typification in the genus <i>Schizochlamydella</i> is problematic, however. The type species of the genus, <i>S. delicatula</i> (West) Korshikov (1953) was transferred to the chrysophycean genus <i>Phaeoschizochlamys</i> Lemmerman (1898) by Bourrelly (1957). However, this transfer was made without pigment or molecular analyses; we regard the choice of <i>Schizochlamys</i> for our material as prudent until the phylogenetic placement of the type species is clearly established.</p> <p> <b>Cultures:—</b> LCR-CG9.</p>Published as part of <i>Novis, Phil M. & Visnovsky, Gabriel, 2012, Novel alpine algae from New Zealand: Chlorophyta, pp. 1-30 in Phytotaxa 39</i> on pages 20-22, DOI: 10.11646/phytotaxa.39.1.1, <a href="http://zenodo.org/record/4894684">http://zenodo.org/record/4894684</a>
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Pseudococcomyxa simplex Fott 1981
No full text<i>Pseudococcomyxa simplex</i> (Mainx) Fott <p> Reference: Novis <i>et al</i>. 2008: 353–354, Fig 3A–I.</p> <p> <b>Observations:—</b> Previously, only data for <i>rbc</i> L were available for this species from Mt Philistine. The 18S data presented here show that <i>Pseudococcomyxa simplex</i> from Mt Philistine is a close relative of <i>P. simplex</i> UTEX 274 (Fig. 8). Both of these strains belong to a clade that includes species of <i>Coccomyxa</i> as well as <i>Paradoxia</i> spp. This clade is distinct from a second clade comprising other species of <i>Coccomyxa</i>; clearly this genus is polyphyletic and requires revision. Interestingly, the oblique division plane characteristic of <i>Pseudococcomyxa</i> (Broady 1987, Novis <i>et al</i>. 2008) is also evident in <i>Paradoxia multiseta</i> Svirenko 1928 during vegetative division (Hegewald & Reymond 1987). Some species currently regarded as <i>Coccomyxa</i>, such as <i>C. confluens</i> (Kützing) Fott 1974, appear to share this feature (Ettl & Gärtner 1995), although how it is distributed phylogenetically is presently unclear. It may be a morphological feature that can be used to separate the two clades.</p>Published as part of <i>Novis, Phil M. & Visnovsky, Gabriel, 2012, Novel alpine algae from New Zealand: Chlorophyta, pp. 1-30 in Phytotaxa 39</i> on page 25, DOI: 10.11646/phytotaxa.39.1.1, <a href="http://zenodo.org/record/4894684">http://zenodo.org/record/4894684</a>
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
No full textWe 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
Dr. Edward P. Wimberly, ITC, July 2011
No full textThis video is a conversation with Dr. Edward P. Wimberly. Dr. Wimberly talks about his book, "No Shame in Wesley's Gospel: A Twenty-First Century Pastoral Gospel". Brad Ost, AUC Woodruff Library, is the interviewer
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