1,720,964 research outputs found
Mathematical Models and Methods related to Cell–Extracellular Matrix Interactions
No full textThis Doctor of Philosophy Dissertation in Matematica per le Scienze dell’Ingegneria is
composed by two distinct parts having in common the study of the interactions between
cells and extracellular-matrix. This is the result of a three year working project
supervised by professors Davide Ambrosi (Politecnico di Milano) and Luigi Preziosi (Po-
litecnico di Torino). In the spirit of the aims and scopes of the Doctoral degree, both
modelling and applications of analytical/numerical methods constitute the backbone of
such a work; in fact, the first part emphasizes the latter aspect whilst the second part is
more focused on the former. Specifically:
1. Part I deals with the mathematical aspects of Force Traction Microscopy. This is an
inversion method that allows to reconstruct the stress field acting on a substratum
knowing the displacement of the substrate itself, measured at some points. The
formulation of this problem in the Inverse/Optimal Control framework together
with its analytical and numerical study constitutes the real aim of this part of
dissertation. Remarkably, some contents of this part had been submitted [70].
2. Part II deals with the mathematical modeling of cell-tissue adhesion. Such an
adhesive property of living tissue seems to be of importance in the developing
of biological process. Moreover, quite a huge amount of experimental data can
be found in the specialistic literature. A Continuum Mechanics point of view
is adopted to describe adhesion and the outcome of our model is qualitatively
compared with experiments. Remarkably, some contents of this part had been
published [59]
A multiphase model of tumour and tissue growth including cell adhesion and plastic re-organisation
No full textThe main aim of the paper is to embed the experimental results recently obtained studying the detachment force of single adhesion bonds in a multiphase model developed in the framework of mixture theory. In order to do that the microscopic information is upscaled to the macroscopic level to describe the dependence of some crucial terms appearing in the PDE model on the sub-cellular dynamics involving, for instance, the density of bonds on the membrane, the probability of bond rupture and the rate of bond formation. In fact, adhesion phenomena influence both the interaction forces among the constituents of the mixtures and the constitutive equation for the stress of the cellular components. Studying the former terms a relationship between interaction forces and relative velocity is found. The dynamics presents a behavior resembling the transition from epithelial to mesenchymal cells or from mesenchymal to ameboid motion, though the chemical cues triggering such transitions are not considered here. The latter terms are dealt with using the concept of evolving natural configurations consisting in decomposing in a multiplicative way the deformation gradient of the cellular constituent distinguishing the contributions due to growth, to cell rearrangement and to elastic deformation. This allows the description of situations in which if in some points the ensemble of cells is subject to a stress above a threshold, then locally some bonds may break and some others may form, giving rise to an internal reorganization of the tissue that allows to relax exceedingly high stresses.</jats:p
Mechanical aspects of tumour growth: Multiphase modelling, adhesion, and evolving natural configurations
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
Vitale, Guido Amedeo
No full textLa Voce ricostruisce la vita e le opere del diplomatico e traduttore attivo in Cina alla fine del XIX secolo
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
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