1,720,981 research outputs found
Evaluation of the Wharton׳s jelly poroelastic parameters through compressive tests on placental and foetal ends of human umbilical cords
Full text linkThe umbilical cord is a conduit between the developing foetus and the placenta. In physiological conditions it contains two arteries and one vein immersed in a mucoid tissue called Wharton׳s jelly. Although the extreme importance of such a structure is fully recognized, the umbilical cord and its components have been scarcely studied. A deep investigation on the biomechanics of the umbilical cord could help to understand if the pregnancy outcome is influenced by umbilical cord mechanical properties, however, detailed biomechanical data are still lacking. In the present study, the mechanical properties during compression of the human Wharton׳s jelly have been evaluated using a poroelastic approach. Multi-ramp stress-relaxation tests in both confined and unconfined configurations were performed on Wharton׳s jelly samples extracted from foetal and placental sides of twenty human umbilical cords. The Young modulus and Aggregate modulus were calculated at three strain levels and the hydraulic permeability was found by fitting the confined stress-relaxation data to the analytical solution and minimizing the stress least square differences. The Wharton׳s jelly exhibits a highly non linear and viscoelastic behaviour showing a dependence on the applied strain values and a ~90% and ~85% relaxation in unconfined and confined configuration, respectively. Moreover, equilibrium Young and Aggregate moduli resulted significantly higher and the permeability significantly lower at the foetal than the placental site, showing a dependence of the three material parameters on the location (foetal or placental) and, consequently, a non-homogeneity in the Wharton׳s jelly mechanical properties
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
Biodegradable scaffolds of chitosan and PEGylated polyesters
No full textIn recent years, research on biomaterials has been directed towards the development and optimization of new scaffolds for tissue regeneration; among the various biomaterials, chitosan has been the subject of numerous studies for potential applications. Chitosan has been used in various applications of bone tissue engineering since it was shown that it is able to promote the growth and deposition of mineral matrix of osteoblasts in culture. Furthermore, chitosan is biocompatible, biodegradable and can be molded into porous structures to promote osteoconduction, thanks also to its ability to bind growth factors and release them in a controlled manner.
Unfortunately, the chitosan alone shows quite low mechanical strength and too fast degradability. Therefore a solution can be represented by the use of a composite material.
The aim of this work is to conjugate the properties of chitosan with those of PEGylated biodegradable polyester like poly(L)-lactide and poly(L-lactide-co-glycolide) to perform scaffold for tissue engineering application. We studied the influence of the synthesized copolymers, obtained by Ring Opening Polymerization, on the structural properties (e.g. porosity, swelling and mechanical behaviour) of the polysaccharide scaffolds.
Chitosan was mixed with either mPEG-g-P(L)LA and mPEG-g-P(L)LGA at a ratio of 1:2 and freeze dried cylindrical samples were prepared, and subsequently thermally cross-linked to produce the composite scaffolds. The prepared scaffolds were observed using a Scanning Electron Microscope (SEM), weighted in dried and wet condition and tested in compression in order to assess their morphology, swelling properties and mechanical strength.
The formation of cross-linked composite of chitosan with either mPEG-g-P(L)LA and mPEG-g-P(L)LGA resulted in scaffold with suitable porous structures and improved mechanical properties. These preliminary results are a fundamental step before the biological characterization with cells
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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