1,721,026 research outputs found
Spring Forward and Fall Back Dynamics in Formation of Somite Boundaries
No full textAbstractOscillating signaling systems mediate the progressive division of mesoderm into segmental units, termed somites. A recent study using time-lapse analysis in living chick embryos has revealed that the process of somite boundary formation relies on a carefully choreographed series of cell movements, which are both unexpected and surprisingly intricate
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
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
Regulated assembly of a prion-like phosphatase, CG5830, controls its phosphatase activity and embryonic development in Drosophila melanogaster
Get PDFPrion-like proteins can assume distinct conformational states in the same cell, and often one of these states leads to a self-assembling oligomer that can vary in physical nature. The conformational state change from monomers to oligomers can act like a switch, and most importantly this switch also leads to a change in protein function, i.e. loss of the original function or gain of a new function. Such protein switches have been shown to be involved in transcriptional regulation, translational regulation and signaling, regulating many different physiological processes such as stress response, memory formation, and immune response. However, it is unclear how common such mechanism(s) are utilized in multicellular organisms and the diversity of the processes they regulate. Here, I report the characterization of CG5830, a candidate a prion-like protein identified through a systematic screen in Drosophila melanogaster. I find that in the Drosophila embryo, CG5830 changes its conformational state from monomers to amyloid like oligomers on the membrane during gastrulation. It functions as a membrane phosphatase required for embryonic patterning and interacts with major regulators of developmental pathways, such as TGF-β, EGF and FGF signaling pathways. Finally, a conformational state change of CG5830 leads to gain of enzymatic function. My data indicate that prion-like protein switches can have essential roles in animal development
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
CONTRIBUTIONS OF THE 3' HOX GENES, HOXA1, HOXB1, AND HOXB2, TO PATTERNING OF THE AXIAL SKELETON DURING DEVELOPMENT
Get PDFTo investigate whether Hoxb1, as well as related proteins Hoxa1 and Hoxb2, are involved in vertebral development, we analyzed the skeletons of 18.5dpc Hoxa1, Hoxb1, and Hoxb2 loss-of-function single and double mutant embryos. Our analysis reveals that loss of Hoxb1 and Hoxb2 function leads to multiple homeotic transformations along the vertebral column. The dosages of both HoxB genes seem to be important, since the homeotic transformations significantly increase in penetrance in Hoxb1/Hoxb2 trans-heterozygotes, compared to single heterozygotes. Through the use of transgenic mouse strains, we were also able to reproduce similar transformations upon addition of extra HoxB gene copies. Interestingly, the defects observed in these loss-of-function mutants and transgenic mice occur at the boundaries between morphologically distinct vertebral domains. In conclusion, these data show that the anterior HoxB genes, particularly, Hoxb1 and Hoxb2, play a critical role in patterning the paraxial mesoderm that will give rise to the axial skeleton
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