1,720,962 research outputs found
Modelling and simulating the organ donation process using bootstrap and event-driven process chain representation
No full textTransplants improve the quality of life and extend lifespan by replacing damaged organs. The duration of the donor management process must be evaluated and shortened to prevent organ degradation. In this paper, we propose an event-process-chain (EPC) model for the donor management process and conduct a Monte Carlo event-driven simulation to assess its overall duration. We give a rigorous description of the current procedure, to be used as a baseline to re-organize the process. Monte Carlo simulation parameters are based on a measurement campaign where the durations of all the activities in the donor management process have been observed. Due to the low number of donors, we employ a bootstrap approach to generate activity times. We evaluate the overall process completion time and identify the most critical activities. The standard deviation of the completion time is just 11.5% of the mean value. Instrumental tests (encompassing diagnostic and analytical procedures) turn out to be the activities to focus on to shorten the completion time significantly. In order to achieve lower organ degradation, policy guidelines should then address the time of execution (e.g. as to consent acquisition) and the duration of those tests
Modelling the consent acquisition time in organ donor management through clustering and mixture probability models
No full textTime is a critical variable in organ transplantation. Brain-dead donors may be or become unstable. Organs are subject to degradation and must be transplanted as soon as possible. An unavoidable source of delay in the process is the time needed to get consent to the donation by the potential donor's relatives. Information about the likely consent acquisition time would allow us to predict and minimize the time needed for the overall harvesting and transplantation process. In this paper, by using a real dataset of consent acquisition time from a local transplantation centre, we identify three clusters associated with early, regular, and late consent-givers and provide a probability model for the consent acquisition time based on a mixture of three gamma components
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
Pulmonary autograft versus homograft replacement of the aortic valve: a prospective randomized trial
No full textVariations 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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