1,720,999 research outputs found
Ancestrale
No full textLa scoperta dell'inedita raccolta Ancestrale di Goliarda Sapienza e il suo posizionamento nella sua oper
Mechanical behaviour of physiological and prosthesized human femurs during stair climbing: a comparative analysis via 3-D numerical simulation.
No full textObjective. The aim of this study is to perform finite element investigation of the mechanical behaviour of a prosthesized human femur during stair climbing. In order to numerically analyze the stress shielding phenomenon in a femoral bone with an artificial hip replacement, the strain and stress distributions both in the femur and in the stem were evaluated by using the finite element method. Methods. From a set of CT images the geometry of the femur was recovered and meshed. An operation of virtual surgery allowed to insert the metal stem (constructed by a CAD code) in the medullary canal. Results. Numerical simulation showed evidence that stresses and strain energy density increase in the distal zone of the stem-bone interface of the prosthesized femur; and hence a load transfer is determined from proximal zones to distal ones. As expected, lateral and medial zones are subjected to, respectively, tensile and compressive normal stresses in z-direction, absolute maxima being attained at the distal part of the diaphysis. Conclusions. The development of a computational model allowed to deal with the complexity of the biomechanical problem and to describe quantitatively the mechanical behaviour of bone tissue in contact with the metal stem. The calculated results motivate the performed analyses because they are sufficient to activate the mechanisms of deposition and resorption in the bone tissue at contact with the artificial biomaterial. Thus, stair climbing confirms to be a critical task for primary stability of the prosthesized femur
Mechanical behaviour of a prosthesized human femur: a comparative analysis between walking and stair climbing by using the finite element method.
No full textThe aim of this study is to perform finite element investigation of the mechanical behaviour of a prosthesized human femur during walking and stair climbing. Such activities are in fact encountered with the highest frequencies during daily living. In order to numerically analyze the stress shielding of the femoral bone with an artificial hip replacement, the strain and stress distributions both in the femur and in the stem were evaluated by using the finite element method. From a set of CT images the geometry of the femur was recovered and meshed. An operation of virtual surgery allowed to insert the metal stem (constructed by a CAD code) in the medullary canal. Numerical simulations showed evidence that, when comparing walking with stair climbing for stresses and strain energy density, maxima and minima values change dramatically, even if the localizations remain the same ones. Furthermore, for each type of daily activity, the unloading of bone tissue is confirmed in the case of prosthesized femur with respect to the physiological one, and hence the well-know phenomenon of stress shielding is exhibited. The development of a computational model allowed to deal with the complexity of the biomechanical problem and to describe quantitatively the mechanical behaviour of bone tissue in contact with the metal stem. The calculated results motivate the performed analyses because they are sufficient to activate the mechanisms of deposition and resorption in the bone tissue at contact with the artificial biomaterial. Thus, stair climbing confirms to be a critical task for primary stability of the prosthesized femur with respect to the activity of walking
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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