1,721,662 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
Impatto ambientale del farmaco veterinario
No full textIl rischio ambientale rappresentato dal potenziale rilascio di farmaci ad uso veterinario nell’ambiente è argomento di crescente interesse. La valutazione del rischio ambientale è ormai parte integrante dei dossier per l’ottenimento dell’autorizzazione all’immissione in commercio di un farmaco. Non tutti i farmaci destano preoccupazione per il loro possibile impatto sull’ambiente: le molecole che sono impiegate in elevati quantitativi (es. trattamenti di massa degli animali da reddito), che possono causare effetti indesiderati agli organismi terrestri ed acquatici non-target o che si dimostrano difficilmente degradabili, sono senza dubbio sostanze prioritarie. E’ inoltre necessario considerare il potenziale inquinamento di falde acquifere, come del resto sottolineato dal reperimento di variabili concentrazioni di alcuni farmaci in matrici come terreno e acqua. La valutazione d’impatto ambientale si basa sull’esposizione, sul destino ambientale e sugli effetti tossici che caratterizzano il principio attivo o i suoi prodotti di derivazione (metabolici o di degradazione). La valutazione del rischio, condotta in due fasi successive in funzione della concentrazione ambientale prevista nel terreno, indica se il potenziale rischio ambientale derivato dall’impiego del farmaco ad un determinato dosaggio in una specifica specie è considerabile accettabile o meno. E’ possibile quindi che alcune misure di attenuazione del rischio vengano presto introdotte nei foglietti illustrativi dei prodotti farmaceutici. Il veterinario è dunque chiamato ad avere un ruolo chiave non solo nel proporre trattamenti farmacologici mirati ma anche in materia di tutela ambientale e di sostenibilità dell’allevamento intensiv
Reduction of carbonylic and carboxylic group's by plant cell cultures
No full textThe transformation of aliphatic and aromatic acids to their corresponding alcohols, involving two reductive steps, is difficult to perform biologically due to its low redox potential. For this reason, the reduction of nonactivated carboxylic acids has been described for only a limited number of substrates and confined to a few microbial groups (fungi, clostridia, and archea). Nine species of cultured plant cells were able to reduce cinnamic, hexanoic, and octanoic acids to the corresponding primary alcohols with yields ranging from 2 to 80% (w/w). Aldehyde was detected only for three species during the reduction of cinnamic acid, confirming that the second reductive step from aldehyde to alcohol is faster than the first, from acid to aldehyde. Lyophilized cells from some of the cultures were used in buffer and solvent-water systems to obtain the reduction of carbonylic (ethyl acetoacetate) and carboxylic (cinnamic and hexanoic acids) groups
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
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