1,720,974 research outputs found
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
In vitro sperm capacitation to treat antisperm antibodies bound to the sperm surface
No full textOur objective was to study antisperm antibody bound to the acrosome region during in vitro capacitation and to determine whether acrosome-antibody free sperm can be obtained from previously acrosome-antibody-coated sperm. The spermatozoa from a selected series of 14 patients were tested for sperm antibodies bound to the sperm surface using d-IBT and focusing on the acrosome positivity. The tests were carried out before the incubation and after 3, 6, 9, and 12 h of incubation in Tyrode's solution with 0.5% human serum albumin as the capacitation medium. Tests to evaluate acrosome region, sperm motion parameters, and zonae binding ability were carried out. In this way we were able to evaluate sperm function during capacitation protocol. The patients were 14 subjects selected according to good seminal characteristics, good post-rise sperm parameters, and high percentage of ASA bound to the sperm surface. In all cases the results showed that antisperm antibodies bound to the acrosome region were shed prior to the acrosome reaction. During sperm capacitation in human a modification, migration, or shedding of plasma membrane molecules takes place. The presence of antibodies in such an important area of the sperm head could certainly interfere in the fertilization process. Our data indicate that in vitro capacitation could provide an in vitro therapy capable of eluting antibodies from the acrosome region
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
Human zona pellucida during in vitro fertilizationan ultrastructural study using saponin, ruthenium red, and osmium-thiocarbohydrazide
No full textThe human zona pellucida (ZP) and its changes during in vitro fertilization in
oocytes at different maturational stages and polypronuclear ova at one- to
four-cells stages were studied by transmission electron microscopy (TEM) and
correlative scanning electron microscopy (SEM). To define the microstructure of
the ZP, its amorphous masking material was removed using a detergent (saponin),
and its structural glycoproteins were stabilized with a cationic dye, ruthenium
red, followed by osmium-thiocarbohydrazide treatment. These methods allowed in
all samples the clear visualization of variously arranged networks of filaments
composing the outer and inner surfaces of the ZP. These filaments were straight
or curved, 0.1-0.4 microns in length and 10-14 nm thick as seen via TEM or 22-28
nm thick as seen via SEM (the difference in thickness was due to the presence of
the metal coating for SEM). The filament arrangement was remarkably different
between the inner and outer surfaces of the ZP and among the various stages
studied. The filaments of the outer surface of the ZP were basically arranged in
"large" and "tight" meshed networks. Mature oocytes and fertilized
(polypronuclear) ova had a regular alternating pattern of wide and tight meshed
networks of filaments. On the other hand, immature and atretic oocytes displayed
almost exclusively a tight meshed network of filaments. The inner surface
filaments of the ZP of unfertilized oocytes at any stage were arranged in
repetitive structures characterized by numerous short and straight filaments
anastomosing with each other and sometimes forming at the intersections small,
rounded structures. After fertilization, the inner surface of the ZP displayed
numerous areas where filaments fused together. Collectively, these data clearly
reveal that oocyte maturation and fertilization in humans are accompanied by
changes of ZP filaments arrangement, which may be relevant in the processes of
binding, penetration, and selection of spermatozo
- …
