1,720,965 research outputs found
Morphological and histochemical features of the luminal epithelium of caudal region of the equine oviduct
No full textThe caudal region of the mammalian oviduct includes the isthmus and utero-tubal junction segments. In equine oviduct a few studies have been performed on the isthmus by means of scanning electron microscopy (SEM) and lectin histochemistry, whereas studies on the interstitial segment of isthmus (ISI) (corresponding to the cow and pig utero-tubal junction) are lacking. These two segments of mare oviducts were processed for SEM and electron transmission microscopy as well as for lectin histochemistry. The ISI showed a narrower lumen and a taller epithelium than isthmus. The epithelium of the both regions contained electron-lucent ciliated cells and two sub-types of non-ciliated (secretory) cell. Most secretory cells in the ISI showed granules characterized by a dense core surrounded by less electron-dense material, whereas a few cells showed an electron-dense cytoplasm containing small electron-dense granules. In the isthmus non-ciliated cells were moderately electron-dense and the two sub-types differed in the number and the electron-density of the granules. Lectin histochemistry showed Galβ1,3GalNAc and sialic acid-Galβ1,3GalNAc in the ISI and Neu5Acα2,6Gal/GalNAc in both segments. These results suggest that during their passage through the ISI and the isthmus spermatozoa move in two different intraluminal milieu which contribute to ensuring the effective condition of the sperm when ovulation occurs
Lectin-binding pattern of Senegalese sole Solea senegalensis (Kaup) testis
No full textThe localization and characterization of oligosaccharide sequences in the testis of Senegalese sole Solea senegalensis was investigated using 12 lectins in combination with KOH saponification and sialidase digestion (K-s). The interstitial compartment contained all the sugar residues investigated, those bearing oligosaccharides terminating with sialic acid (Neu5Ac) alpha 2,3Gal beta 1,4GlcNAc, Neu5AcGalNAc alpha 1,3(LFuc beta 1,2) Gal beta 1,3/4GlcNAc beta 1 and GalNAc alpha 1,3(LFuc1,2) Gal beta 1,3/4GlcNAc beta 1 being more abundant in the medullar region than in the cortex. The melanomacrophage centres found in the interstitial compartment displayed glycans terminating with Gal beta 1,3GalNAc. The basal lamina separating the germinal and interstitial compartments exhibited glycans with terminal/ internal mannose, internal beta GlcNAc, and terminal Neu5Ac alpha 2,6Gal/GalNAc, and Neu5AcGal beta 1,3GalNAc, Gal beta 1,3GalNAc (PNA), Gal beta 1,4GlcNAc, GalNAc, alpha Gal, and alpha L-Fuc. In the germinal compartment, the Sertoli cells expressed only glycans terminating with Neu5Ac alpha 2,3Gal beta 1,4GlcNAc in the apical and supranuclear lateral surface of the spermatonial cysts located in the distal part of the seminiferous lobules. Primary spermatocytes exhibited oligosaccharides terminating with Gal beta 1,3GalNAc and alpha GalNAc in the cytoplasm and nucleus, respectively. The spermatids contained highly mannosylated glycans terminating with GalNac, alpha Gal, and alpha L-Fuc. The head of spermatozoa expressed a more complex glycosylation pattern characterized by the additional presence of oligosaccharides terminating with Neu5Ac alpha 2,3Gal beta 1,4GlcNAc, Neu5AcGal beta 1,3GalNAc, Neu5AcGalNAc alpha 1,3(LFuc alpha 1,2)Gal beta 1,3/4GlcNAc beta 1, GalNAc alpha 1,3(LFuc alpha 1,2)Gal beta 1,3/4GlcNAc beta 1. The comparison with previous lectin histochemical studies carried out in other fish species reveals a specific glycosylation pattern of Senegalese sole testicular structures and spermatozoa head
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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