1,721,055 research outputs found
Abuse of narcotics: survey of deaths referable to the Procura della Repubblica of Milano and Monza
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La determinazione di nicotina e cotinina nei capelli di bambini esposti al fumo di sigaretta
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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
Valutazioni preliminari di un metodo GC/MS/MS per la determinazione quantitativa del THC-COOH in matrice pilifera
No full textTra tutte le sostanze stupefacenti di maggior diffusione, il delta-9-tetraidrocannabiolo è quella che presenta la minor dose efficace (5 mg nella preparazione). Tenuto conto che per le modalità di assunzione, la combustione abbatte di oltre il 30% la concentrazione presente negli spinelli, le concentrazioni biologiche che ne derivano sono notevolmente inferiori a quelle, ad esempio, determinate dalla cocaina o dall'eroina. Anche la dimostrazione dell'uso pregresso attraverso l'analisi delle matrici pilifere, comporta un approccio analitico diverso, sostanzialmente caratterizzato da un valore di riferimento che rappresenta non più del 10% di quello assegnato alle altre sostanze. Recentemente si è resa indispensabile la determinazione dell'acido11-nor-delta-9-tetraidrocannabinol-9-carbossilico anche nelle matrici pilifere, al fine di ottenere la dimostrazione di un'esposizione attiva allo stupefacente e dissipare ogni dubbio in ordine alla possibilità di una contaminazione ambientale. Sebbene questa sostanza rappresenti il metabolita principale e più abbondante del delta-9-THC, le sue caratteristiche chimiche non sono favorevoli ad una sua incorporazione nelle matrici pilifere e le concentrazioni che si originano sono di oltre 100 volte inferiori al cut-off della molecola originale. La disponibilità di tecniche analitiche altamente sensibili amplificano la possibilità di rilievo, ma incrementano la probabilità di interferenze, per cui stretta è la necessità di validare accuratamente i metodi analitici. Il lavoro qui descritto riguarda gli obiettivi preliminari (efficacia estrattiva, specificità, sensibilità strumentale, linearità), finora raggiunti con l'applicazione di un metodo analitico mirato alla determinazione dell'acido11-nor-delta-9-tetraidrocannabinol-9-carbossilico in matrice pilifera. Il metodo analitico applicato a 50 mg di capelli si caratterizza dei seguenti parametri: LOD 0,06 pg/mg, LOQ 0,09 pg/mg, recupero medio 52,3%, riproducibilità intraday compresa tra 4,8% e 6,5%, r2 0,9995. Nel 73,4% dei campioni positivi al delta-9-THC (n=45) il metabolita è stato rilevato in concentrazione superiore al LOQ del metodo (0,09 pg/mg)
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