1,720,954 research outputs found
Physics of tissue fluidity and collective cell motion in epithelia
Full text linkCollective cell migration is essential in many fundamental biological processes. During morphogenesis, cells display highly coordinated shape changes, rearrangements, and motion. During wound healing, cells must coordinate their migration to close gaps in epithelial tissues to prevent infection. The efficiency of these processes is determined by the fluidity of the tissue --- the ability for cells to rearrange and remodel, which in turn is governed by the mechanics of both the cells and their environment. In this thesis, I use computational methods to investigate the origin of tissue fluidity, and its role on collective cell motion. In Part I, I investigate how tissue fluidity governs collective cell motion during wound healing. We find that the ability for cells to rearrange, preventing jamming, is essential for closure. Despite contractile tension around the gap driving closure, reducing tension in the cells increases tissue fluidity and healing rates. In Part II, I study how cells optimise their active behaviour, either contraction or crawling, to regulate tissue fluidity for rapid motion. In wound healing, we find that a balance of the two modes is most efficient over a wide range of cell, substrate, and tissue properties. In Part III, I study how tissue fluidity regulates force transmission in cell colonies. For stiff cells, the tissue acts like a giant single-cell, with traction forces distributed around the colony periphery, but as tissue fluidity increases, forces localise to the interior of the colony. Tissue fluidity requires that cells are able to rearrange and change shape, which in turn is regulated by adaptive viscoelastic properties of the junctions. Thus, in Part IV, I develop a new theory for how cell-cell junctions remodel under stress; strain above a threshold triggers tension remodelling and irreversible length changes. This enables tissue shape change and homeostasis that is robust to fluctuations in stress. Overall, this work demonstrates the important role of single cell mechanics and tissue fluidity on regulating collective cell behaviours
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
Supplemental data to "A mechanical ratchet drives unilateral cytokinesis"
No full textThis dataset presents raw imaging data, quantitative measurements, and data visualisation code from zebrafish embryo experiments investigating contractile band dynamics during early cell division. The study examines the mechanical processes that drive unilateral cytokinesis, focusing on cytoskeletal organization across the cell cycle. High-resolution time-lapse microscopy and quantitative image analysis were used to capture and assess the cellular behaviours
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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