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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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 ultrastructure of the human cumulus matrix. Ultrastructural three-dimensional and immunochemical observations.
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Ultrastructural features of bovine cumulus-corona cells surrounding oocytes, zygotes and early embryos
No full textIntegrated transmission and scanning electron microscopic (TEM and SEM)
techniques have provided the first detailed description of the ultrastructural
features of the bovine cumulus-corona (CC) cells surrounding oocytes at the time
of final maturation, zygotes and early cleaving embryos (2/4 to 6/8 blastomeres).
TEM revealed the presence of rough endoplasmic reticulum and Golgi complexes in
the cytoplasm of CC cells surrounding immature, mature and fertilized eggs, and
also revealed an increasing amount of smooth endoplasmic reticulation membranes,
lipid droplets and mitochondria with villiform and/or tubular cristae in the
cytoplasm of CC cells during maturation and fertilization of the oocyte. In
addition, a loss of cell-to-cell junctions between CC cells was evident. TEM also
demonstrated that a few residual CC cells were still associated with early
embryos and that these cells showed rather degenerative or apoptotic patterns,
the latter pattern also observed on cells associated with fertilized eggs. SEM
revealed that the complex of CC cells of immature oocytes was compact with narrow
intercellular spaces, which progressively enlarged in size around mature oocytes.
This phenomenon is mostly due to the production of abundant extracellular matrix.
Immature CC cell complexes possessed characteristic long and filiform microvilli
whereas the surface of CC cells surrounding mature oocytes showed numerous blebs
and occasional large cytoplasmic protrusions as well as microvilli. Zygotes and
early embryos were covered with a few polyhedral CC cells possessing scarce and
short microvilli and a large amount of pleomorphic blebs. This study demonstrated
a precocious luteinization occurring in bovine CC cells at ovulation until zygote
segmentation, and this process was associated with a progressive apoptotic
mechanism that ended in the complete denudation of the zona pellucida covering
the early embryo. The presence of CC cells around the maturing oocyte and
fertilized egg could have important functions related to the microenvironmental
requirements of ovum maturation as well as facilitating activities related to
fertilizatio
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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