1,721,007 research outputs found
The fine structure of the mature spermatozoon of Onchidella celtica (Cuvier) (Mollusca: Gastropoda) and its phylogenetic implications
No full textThe spermatozoon of Onchidella celtica shows many peculiar features. The acrosome is formed by an apical vesicle and a pedestal consisting of a principal body which is flanked by two electron-dense elliptical elements. The mitochondrial derivative consists of three different components: peripheral layers of paracrystalline material, concentric cisterns, and two cylindrical compartments. The 9 + 9 + 2 axoneme shows 9 small deposits of glycogen granules in correspondence with the axonemal “spokeheads,” and a small assembly of possibly proteic material lying close to the two central tubules. Another intraaxonemal deposit of glycogen granules is present at the level of the “glycogen piece.” Most of the observed features are in substantial agreement with those of another species of the Onchidiidae. This confirms the constancy of sperm structure among the members of a single family of the Gastropoda
Morphological modifications in stored heterospermatozoa of Oxyloma elegans (Pulmonata: Stylommatophora)
No full textThe authors describe a peculiar feature of the sperm of Oxyloma elegans (Pulmonata: Stylommatophora) which consists in a paracrystalline body encircling the apical portion of the nucleus. This body has been seen to vanish when spermatozoa are stored in the seminal receptacles after copulation. The meaning of this phenomenon and its possible relationship to capacitation are discussed
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
The seminal receptacle and sperm storage in Cochlostoma montanum (Issel) (Gastropoda: Prosobranchia)
No full textFemales of Cochlostoma montanum (Prosobranchia, Cochlostomatidae) have a seminal receptacle which is not a separate diverticulum of the oviduct. The seminal receptacle derives from a differentiated portion of the renal oviduct which has an inner wall composed of only one layer of cells. These cells are of two different types, both actively involved in secretory activity. One type is represented by goblet cells filled with large vesicles containing an electron‐dense, homogeneous, and partially paracrystalline material. This material is expelled into the lumen through macro‐apocrine or holocrine types of secretion. The other type is represented by ciliated cells rich in small vesicles containing granular material. Probably neither kind of secretion has a nutritive function; rather they serve as matrix for spermatozoa that immobilize them and prevent their expulsion from the receptacular portion of the oviduct. Spermatozoa are inserted in invaginations of the apex of both these epithelial cells. The sperm plasma membrane covering the acrosome forms long digitations which expand toward the corresponding invaginations of the receptaculum cells. This type of adhesion is a novelty for Mollusca and resembles that in seminal receptacles of some Annelida
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
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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