1,721,064 research outputs found
Caratterizzazione dinamica in regime di grandi segnali di effetti dispersivi in bassa frequenza in FET III-V
No full textLa modellistica a grande segnale di dispositivi FET III-V, quando sono richieste elevate capacità di predizione, non può essere basata semplicemente sulle caratteristiche DC i/v. Infatti, devono essere presi in considerazione i fenomeni dispersivi dovuti ad autoriscaldamento eo alla presenza di trappole (stati superficiali e livelli profondi) essendo questi la causa di importanti deviazioni nelle caratteristiche dinamiche della corrente di drain a bassa frequenza. Per tale motivo risulta necessario sostituire alle semplici caratteristiche statiche un idoneo modello che tenga conto della presenza di effetti dispersivi in bassa frequenza. Diversi approcci sono stati proposti dalla comunità scientifica e spesso la caratterizzazione tramite sistemi di misura i/v impulsati è stata indicata come la più appropriata per l’identificazioni di modelli a grande segnale ed a bassa frequenza. Quale possibile alternativa a tali sistemi di misura, dedicati ed altresì alquanto costosi, viene adottato in questo lavoro un nuovo sistema di misura a grande segnale, basato semplicemente su eccitazioni sinusoidali a bassa frequenza, facilmente riproducibile con strumentazione convenzionale e general-purpose. Il sistema viene impiegato per estrarre due modelli per la descrizione delle caratteristiche i/v dinamiche a bassa frequenza di dispositivi PHEMT. Nel lavoro vengono anche mostrate le capacità di predizione di entrambi i modelli ed il confronto con misure di intermodulazione a 40GHz
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
Ripening of banana fruit monitored by water relaxation and diffusion H-1-NMR measurements
No full textWater transverse relaxation times T2 and self-diffusion coefficients D have been measured on banana samples at different ripening stages. Relaxation data have been interpreted on the basis of a chemical and diffusive exchange,model proposed by Belton and Hills [Mol. Phys. 61(4) (1987) 999] and Hills et al. [Mol. Phys. 67(4) (1989) 903]. According to that model the observed increase of T-2 values of both cytoplasmatic and vactiolar water may be mainly attributed to the decrease of starch concentration during the ripening process. On the other hand, the observed water self-diffusion coefficient decrease is related to sugar accumulation as starch hydrolysis proceeds. At the early stages of ripening, the individual self-diffusion coefficient values of cytoplasmatic and vacuolar water differ from one another and have been calculated through the analysis of relaxation time-separated pulsed field gradient nuclear magnetic resonance experiments [J. Magn. Reson. A 112 (1995a) 237]. (C) 2004 Elsevier Ltd. All rights reserved
Valutazioni chimico-fisiche sulle interazioni lacrime artificiali e lenti a contatto in idrogel
No full textLa valutazione delle interazioni tra diversi campioni di lacrime artificiali (soluzioni di ialuronato di sodio o d’idrossipropil cellulosa) e materiali per lenti a contatto (copolimeri di 2-HEMA) è stata realizzata mediante Spettroscopia di Risonanza Magnetica Nucleare (RMN) a bassa risoluzione. In particolare, sono stati analizzati i parametri di moto RMN dell’acqua: tempi di rilassamento e coefficienti d’autodiffusione. I risultati non hanno evidenziato sostanziali cambiamenti nelle possibilità di diffusione delle molecole d’acqua nelle soluzioni di lacrime artificiali, rispetto a quelle misurate nella soluzione fisiologica. Come atteso, è stata rivelata una differenza nei valori dei tempi di rilassamento nelle varie soluzioni da attribuirsi quantitativamente alle diverse caratteristiche fisico-chimiche dei campioni. Ulteriori misure sono state effettuate sui polimeri, sia a carattere non ionico che ionico, che, dopo una lunga permanenza nelle soluzioni, risultavano rigonfiarsi e formare gel ad alta concentrazione d’acqua. Utilizzando i dati relativi ai campioni rigonfiati nella soluzione fisiologica come riferimento, è stato possibile valutare l’interazione tra gli idrogel e le lacrime artificiali.
Tale confronto ha rivelato un diverso comportamento dei materiali ionici rispetto a quelli non ionici nel trattenere l’acqua al proprio interno e nell’interazione con le lacrime artificiali.
Per i campioni ionici con maggiore possibilità di rigonfiamento è stata evidenziata la possibilità di inglobare ioni, se presenti nelle soluzioni, che possono far variare le caratteristiche chimico-fisiche del materiale
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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