1,720,958 research outputs found
DEVELOPMENT OF MEASUREMENT METHODOLOGIES IN METROLOGY FOR CELL BIOLOGY AND REGENERATIVE MEDICINE
Full text linkAim of this thesis is the development of measurement methodologies in metrology for cell biology and regenerative medicine. Regenerative medicine is a novel branch of medicine based on the use of autologous stem cells and biocompatible medical devices to regenerate and repair damaged tissues of patients, i.e. by using three-dimensional scaffolds to implant stem cells into the tissue to be regenerated. Stakeholders of metrology for regenerative medicine are: health care providers who require safe, reliable and cost effective treatments, supported by evidence and approved by regulators; regulators who require standard materials and traceable data demonstrating the safety and efficacy of new products and treatments; medical products companies who require advanced and traceable techniques to develop new products and need methods to measure processes, such as cell growth on scaffolds, to ensure quality and efficiency of the medical products implanted into the patients. Consequently, regenerative medicine has the important requisite of a real time monitoring and not invasiveness neither destructiveness processes to measure the cell-scaffold interactions, in order to preserve the samples from any contamination or modification. Thus non-invasive measurement methodologies need to be developed for analysing the 3D cell culture on scaffolds and, in order to evaluate the uncertainty, highly reproducible measurement procedures are strongly required to minimize the type A uncertainties and to define the type B uncertainties. The non-invasive and non-destructive measurement of cell-scaffold interactions (i.e. stem cell proliferation and differentiation on scaffolds) is one of the most effective methodology to answer the need of testing the efficacy of the design, production/manufacturing, development and performances of stem cell-scaffold products. To satisfy the requirements and the needs for metrology in regenerative medicine, for this thesis it has been chosen to develop a measurement methodology for cellular activity (proliferation and differentiation) on 3D Biocoral® scaffolds and to conduce a metrological study to evaluate the uncertainty of the methodology. This thesis has been developed in the Bioscience group of the Italian National Metrological Institute (Istituto Nazionale di Ricerca Metrologica - INRIM). The main important contributes of this thesis to the metrology in biosciences have been: • to lay the foundations for a metrological approach to cell biology and particularly to regenerative medicine research and applications; • to address the filling of the lack of traceability in the metrology for cell biology metabolic methodologies used to evaluate cellular activities in living sample with non-invasive procedures. The main results and originalities achieved during this PhD work are: • a metabolic assay, the resazurin/resorufin assay, for the first time, has been metrologically characterized and the uncertainty of the measurement has been evaluated; • the resazurin/resorufin assay has been for the first time tailored for a 3D cell culture on Biocoral® scaffolds and the uncertainty of the measurement has been evaluated; • it was demonstrated that Biocoral® induces osteodifferentiation of stem cells and for the first time it was demonstrated on human mesenchymal stem cells; • it was demonstrated, for the first time, that the resazurin/resorufin metabolic assay can be a methodology to detect not only the proliferation but also the differentiation of stem cells on Biocoral® scaffolds; A description of the METREGEN regional project, which this thesis is part of, will follow in the introduction. The chapter 1 will give an overview on regenerative medicine field and its application with scaffolds, particularly referring to the Biocoral® scaffold. The resazurin/resorufin methodology will be deeply described in chapter 2 with a uncertainty budget evaluation and discussion. Chapter 3 will present in details a series of experiments made to establish and characterize a hMSCs in vitro 2D culture, establish a hMSCs in vitro 3D culture on Biocoral, tailor the resazurin/resorufin assay for 3D cell culture on Biocoral and evaluate the hMSCs osteodifferentiation induced by Biocoral scaffolds. All the results have been analysed with a metrological approach to evaluate the uncertainty. Finally, the conclusion will give a recapitulation and some interesting perspective of employment for the resazurin/resorufin methodology to final users, such as the cell factorie
Thermo-Mechanical Analysis of Isotropic and Orthotropic Beams using a Unified Formulation
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Evaluation of various through the Thickness and Curvature approximations in Free vibration analysis of cylindrical Composites Shells
No full textThis paper presents a comparison of various, significant shell theories to evaluate the free vibration response of multi-layered, orthotropic cylindrical shells. Carrera unified formulation for the modelling of composite spherical shell structures is adopted. Via this approach, higher order, zig-zag, layer-wise and mixed theories can be easily formulated. As a particular case, the equations related to Love's approximations and Donnell's approximations and as well as of the corresponding classical lamination and shear deformation theories (CLT and FSDT) are derived. The governing differential equations of the dynamic problem are presented in a compact general form. These equations are solved via a Navier-type, closed form solution. Thin and moderately thick as well as shallow and deep shells are investigated. Several parametric analyses are carried out depending on the stacking sequences of laminates, on the degree of orthotropic ratio and the thickness and on the curvature parameters. Conclusions are drawn with respect to the accuracy of the theories for the considered lay-outs and geometrical parameter
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
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