1,721,078 research outputs found
Reliability assessment of different HVDC technologies by means of Multi-State Matrix approach
No full textThe purpose of this paper is to assess the availability of different HVDC transmission system technologies (LCC and VSC) for different transmitted power capacities in order to compare the strengths and weaknesses of each configuration. The matrix-based system reliability (MSR) method has been used since it turns out to be one of the best methods for reliability assessment of multi-terminal HVDC (MTDC) transmission systems taking into account multiple derated states. The results of this study can be useful in the planning and designing stage of HVDC systems
Screening salivare della malattia celiaca in bambini e adolescenti geneticamente predisposti
Full text linkIntroduzione: La celiachia (CD) è un disordine multifattoriale in cui il test genetico è di rilevanza clinica fondamentale. La malattia, infatti, solo raramente si sviluppa in assenza di aplotipi HLA-DQ2 e/o HLA-DQ8. Il quadro clinico della CD è estremamente variabile e, spesso, i pazienti sono asintomatici; pertanto, è di fondamentale importanza un intervento di prevenzione mirato alla diagnosi precoce di malattia nei soggetti a rischio.
Obiettivo: Screening salivare mediante determinazione degli anticorpi anti-transglutaminasi IgA (TGA-IgA) con metodica radioimmunologica (RIA) per la diagnosi precoce di CD in una coorte di soggetti geneticamente predisposti.
Metodi: Sono stati arruolati 883 bambini frequentanti due scuole primarie del Comune di Roma e 91 familiari di I grado di pazienti celiaci seguiti presso l’ambulatorio di Gastroenterologia Pediatrica del Policlinico Umberto I. 289 scolari e 70 familiari sono risultati geneticamente predisposti. 359 campioni di saliva sono stati raccolti e analizzati per il dosaggio dei TGA IgA con metodo RIA; contestualmente sono stati raccolti 359 campioni di siero per la determinazione dei TGA-IgA con metodo RIA ed ELISA. I bambini con TGA-IgA positivi sono stati successivamente inseriti nell’iter diagnostico previsto dalle Linee Guida ESPGHAN 2020. La sensibilità e la specificità di entrambe le metodiche sono state calcolate confrontando i risultati con le diagnosi eseguite secondo i criteri EPSGHAN 2020. Il test salivare è stato confrontato con la metodica ELISA su siero mediante l’utilizzo del test di Mc Nemar.
Risultati: In una prima fase dello studio sono stati arruolati 359 soggetti geneticamente predisposti. Di questi, 19 bambini (5.3%) sono risultati positivi al test salivare: 16 bambini (84.2%) sono stati confermati alla determinazione sierologica con metodo RIA ed ELISA ed hanno ricevuto la diagnosi di CD; in particolare, 9 hanno mostrato valori di anticorpi TGA-IgA superiori di 10x il range di riferimento e anti-endomisio (EMA) positivi, mentre i restanti 7 bambini con valori inferiori a 10x sono stati sottoposti ad esofagogastroduodenoscopia (EGDS) che ha mostrato le tipiche lesioni istologiche. Un bambino (5.3%) con screening salivare positivo confermato con metodica RIA sul siero, ma con anticorpi negativi con ELISA è stato sottoposto ad EGDS che ha confermato la diagnosi. 2 bambini (10.5%) con valori salivari debolmente positivi non si sono confermati sul siero con entrambi i metodi e non hanno proseguito il follow-up.
Due dei 340 bambini (0.6%) con screening salivare negativo hanno mostrato valori sierici positivi con metodo RIA ed ELISA e hanno ricevuto la conferma istologica di CD. I restanti 338 bambini (99.4%) negativi al test salivare si sono confermati negativi alle determinazioni sierologiche con entrambi i metodi.
Il test salivare con metodo RIA ha mostrato una sensibilità pari a 94.4% (IC 95% 0.914-0.965) e una specificità pari a 99.4% (IC 95% 0.977-0.999); la sensibilità e specificità del metodo RIA su siero sono state del 100% (IC 95% 0.987-1); quelle del metodo ELISA sono state rispettivamente del 94.7% (IC 95% 0.918-0.967) e 100% (IC 95% 0.987-1). Il test di Mc Nemar ha mostrato la completa sovrapponibilità dei due test in esame (p=1).
Conclusioni: La metodica RIA su saliva ha mostrato risultati sovrapponibili a quelli ottenuti su siero con metodica ELISA; potrebbe rappresentare pertanto un valido test di screening affidabile, semplice, riproducibile, economico e non invasivo. Insieme al kit Gene Celiac Screen, anch’esso poco invasivo, di facile utilizzo ed economico, potrebbe essere inserita in una strategia di screening di massa per la celiachia
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
Availability analysis of HVDC-VSC systems: A review
No full textThis work stems from the worldwide increasing need to precisely consider, in the design
phase of an HVDC project, the availability of the HVDC system. In this paper, an overview of the
availability assessment methods for HVDC-VSC transmission systems is presented. In particular, the
state of the art of the procedures to estimate the availability of both the HVDC link reparable
components and the conversion system on the basis of the converter configuration is given.
The theoretical fundamentals of each method, together with their practical applications, have
been described, in order to highlight the limits and the potentialities of each approach. The authors
aim at giving a guide to choosing the best computation approach on the basis of the specific needs
of the users and at summarizing all the key aspects which can be taken into account during the
availability assessment of HVDC-VSC links
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
Reliability assessment of a multi-state hvdc system by combining markov and matrix-based methods
Full text linkThe purpose of this paper is to highlight that, in order to assess the availability of different HVDC cable transmission systems, a more detailed characterization of the cable management significantly affects the availability estimation since the cable represents one of the most critical elements of such systems. The analyzed case study consists of a multi-terminal direct current system based on both line commutated converter and voltage source converter technologies in different configurations, whose availability is computed for different transmitted power capacities. For these analyses, the matrix-based reliability estimation method is exploited together with the Monte Carlo approach and the Markov state space one. This paper shows how reliability analysis requires a deep knowledge of the real installation conditions. The impact of these conditions on the reliability evaluation and the involved benefits are also presented
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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