1,720,982 research outputs found
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
Polimorfismo ed espressione del gene ppe44 in isolati clinici di Mycobacterium tuberculosis
No full textLe proteine PPE di Mycobacterium tuberculosis, definite sulla base del motivo aminoacidico Pro-Pro-Glu, costituiscono una famiglia di 69 proteine polimorfiche ricche in glicina ritenute una probabile fonte di variabilità antigenica del bacillo tubercolare. Nel nostro laboratorio, nell’ambito di ricerche sul ruolo immunologico della proteina PPE44 nell’infezione tubercolare, è stato studiato l’eventuale polimorfismo e l’espressione del gene ppe44 in isolati clinici rappresentativi delle principali linee filogenetiche di M. tuberculosis. L’analisi PCR-RFLP mediante tre diversi enzimi di restrizione ha mostrato profili di digestione identici in tutti gli isolati; inoltre, la sequenza nucleotidica del gene ppe44 degli isolati non ha evidenziato mutazioni, ad eccezione di una sostituzione nucleotidica in posizione 581 (TTC→TCC, Phe→Ser) ritrovata unicamente negli isolati di genotipo Beijing. L’espressione di ppe44 negli isolati clinici, determinata mediante real-time RT-PCR quantitativa, normalizzata rispetto al gene di riferimento costitutivamente espresso sigA e confrontata con quella del ceppo di riferimento H37Rv, è risultata notevolmente variabile negli isolati clinici, rivelandosi paragonabile a quella di H37Rv in circa il 25% degli isolati, significativamente aumentata nel 60% degli isolati e diminuita nel rimanente 15%; gli isolati di genotipo Beijing hanno mostrato elevati livelli di espressione di ppe44. Tali risultati dimostrano quindi una sostanziale conservazione del gene ppe44 ed, al tempo stesso, una marcata variabilità dell’espressione di ppe44 tra gli isolati clinici. Per valutare se tale variabilità di espressione sia potenzialmente in grado di influenzare la risposta immunitaria dell’ospite, è stata determinata la risposta anticorpale anti-PPE44 in pazienti con tubercolosi in atto ed in soggetti sani con infezione tubercolare latente. E’ stata così dimostrata un’ampia variabilità nella risposta immunitaria verso PPE44 in pazienti con infezione tubercolare sia per quanto riguarda i titoli anticorpali, sia per quanto riguarda la proporzione dei soggetti rispondenti. Tali risultati suggeriscono che l’espressione differenziale dei geni ppe possa costituire una fonte di variabilità antigenica che può quindi avere implicazioni nella immunopatogenesi della tubercolosi
Synthesis and pharmacokinetic behaviour of ester derivatives of 4-isobutylphenyl-2-propionic acid (Ibuprofen) with end-hydroxylated poly(N-vinyl pyrrolidinone) and poly(N-acryloyl morpholine) oligomers
No full textFour derivatives of 4-isobutylphenyl-2-propionic acid (Ibuprofen), in which the drug was bound by ester linkages to poly(ethylene glycols) (PEG 2000-I), monomethoxy poly(ethylene glycols) (PEG 1900-I), poly(N-vinyl pyrrolidinone) (PVP-I) and poly(N-acryloyl morpholine) (PACM-I), all having approximatively the same number average molecular weight (Mn≃ 2000), were prepared and tested for their pharmacokinetic properties after oral administration. It was found that the two end-hydroxylated amphiphilic oligomers of polyvinylic structure, PACM and PVP, whose physico-chemical properties are comparable to those of PEGs especially as regards solvent affinity, have in principle a similar potential as promoieties for preparing oligomeric prodrugs. © VSP 1997
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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