1,720,984 research outputs found
A novel approach to assess reliability in computation of perfusion CT indexes
No full textDynamic contrast-enhanced CT imaging is widely
used in the current clinical practice to provide functional
indexes of activity of organs. Perfusion CT has
imposed itself as one of the most important techniques
to assess the effectiveness of treatments for
liver and lung cancer. However, respiratory movements
and the calculation of perfusion indexes may
introduce artifacts and errors, ultimately affecting
the examination reliability.
In this work, we present the approach devised
to achieve robust perfusion indexes, also proposing
our strategy to help selecting reliable values only.
Two temporal signal models have been compared
as well as the perfusion index values computed accordingly.
Numerical analysis and visual evaluation
confirm the effectiveness of our approach to detect
unreliable values even when they come from robust
models
La Arteriografia TC nello studio delle complicanze arteriose dopo trapianto ortotopico di fegato.
No full text
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
Electrokinetic effects across Nafion 120 membranes
No full textThe electroosmotic coefficient, and the streaming potential across Nafion 120 membrane separating two uni-univalent electrolyte solutions of the same concentration have been studied. Different electrolytes have been considered, namely NaCl, LiOH, NaOH, KOH and CsOH. According to the non-equilibrium thermodynamic theories the ratio (Δφ/ΔP)/(Jv/I), with (Δφ)(electrical potential)/(gDP)(pressure difference) the streaming potential and Jv(volume flow)/I(electrical current flow) the electroosmotic quantity, approaches the unity
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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