1,720,997 research outputs found
Nodal myosin distribution in the bovine heart during prenatal development. An immunohistochemical study.
No full textA novel type of cardiac myosin heavy chain, immunologically related to the myosin
isoforms expressed during skeletal muscle development, has recently been
described in sinoatrial and atrioventricular nodal fibers of the adult bovine
heart (Gorza et al, J Cell Biol 1986; 102:1758-1766). The tissue-specific
expression of this myosin type has been utilized in the present study to
investigate the differentiation of nodal fibers during cardiac development. In
4-6-week-old bovine embryos, reactivity for nodal myosin was observed in a
cluster of cardiac fibers in the sinus venosus wall, corresponding to the
sinoatrial node primordium and in a number of fibers localized in the left atrial
wall, especially in proximity to vascular orifices, possibly corresponding to the
postulated left-sided sinoatrial node. In contrast, reactivity for nodal myosin
was not detected in the atrioventricular node until 12 weeks of gestation. Before
this stage, fibers reactive for nodal myosin were also seen scattered in the left
atrial wall and interatrial septum, raising the possibility that atrioventricular
nodal fibers may derive from the left-sided sinoatrial node. Reactivity for nodal
myosin was never seen in normal atrial and ventricular myocardium, nor in the
ventricular conduction tissue, indicating that nodal myosin does not represent a
primordial myosin form, but is rather a specific marker of a distinct muscle cell
lineage
Myosin types and fiber types in cardiac muscle.III. Nodal conduction tissue.
No full textThe sinoatrial (SA) and atrioventricular (AV) nodes are specialized centers of
the heart conduction system and are composed of muscle cells with distinctive
morphological and electrophysiological properties. We report here results of
immunofluorescence and immunoperoxidase studies on the bovine heart showing that
a large number of SA and AV nodal cells share a distinct type of myosin heavy
chain (MHC) which is not found in other myocardial cells and can thus be used as
a cell-type-specific marker. The antibody used in this study was raised against
fetal skeletal myosin and reacted with fetal skeletal but not with adult skeletal
MHCs. Both atrial and ventricular fibers, as well as fibers of the ventricular
conduction tissue were unlabeled by this antibody. Specific reactivity was
exclusively seen in most cells in the central portions of the SA and AV nodes and
rare cells in perinodal areas. However, a number of nodal cells, particularly
those located in the peripheral nodal regions, were unreactive with this
antibody. The myosin composition of nodal tissues was also explored using two
antibodies reacting specifically with alpha-MHC, the predominant atrial isoform,
and beta-MHC, the predominant ventricular isoform. Most nodal cells were reactive
for alpha-MHC and a number of them also for beta-MHC. Variation in reactivity
with the two antibodies was also observed in perinodal areas: at these sites a
population of large fibers reacted exclusively for beta-MHC. These findings point
to the existence of muscle cell heterogeneity with respect to myosin composition
both in nodal and perinodal tissues
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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