1,721,008 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
Effect of the farming site and harvest time on the nutritional, elemental and volatile profile of mussels: A comprehensive analysis of the PDO ‘Cozza di Scardovari’
Full text link: This study comprehensively characterised a protected designation of origin mussel 'Cozza di Scardovari' (Mytilus galloprovincialis) by examining how it is affected by the farming site (outer vs. inner area of the lagoon) and harvest time (21 April vs. 18 May vs. 16 June). Harvest time affected the marketable traits and fatty acid profile of mussels, whereas farming site scarcely affected marketable traits and mussel yields. Mussels from the inner area of the lagoon displayed a superior nutritional profile, including higher contents of proteins (7.8% vs. 7.4%; P < 0.05), lipids (1.2% vs. 1.0%; P < 0.001) and essential amino acids such as tryptophan (+24%; P < 0.05) and valine (+8%; P < 0.05), with a more favourable n-3/n-6 ratio (7.7 vs. 7.0; P < 0.001) than those from the close-to-sea area. Volatile organic compounds, mainly octanoic acid, dimethyl sulphide and 1-penten-3-ol, differed between farming sites within the same lagoon
Withering of plucked Trachelospermum jasminoides (star jasmine) flowers – Time-dependent volatile compound profile obtained with SPME/GC–MS and proton transfer reaction-mass spectrometry (PTR-MS)
No full textIn this study, the automated application of proton transfer reaction-mass spectrometry (PTR-MS), SPME/GC–MS (solid phase micro-extraction/gas chromatography-mass spectrometry) and multivariate data analysis (chemometry) to the time-dependent changes of Volatile Organic Compound (VOC) patterns of Trachelospermum jasminoides (T. jasminoides) (star jasmine) flowers are studied. The withering of plucked whole T. jasminoides flowers over a thirteen day range is investigated by monitoring the change of VOC release over time since plucking. Three phases with strong differences in the quantities of VOCs between measurements were seen, with a burst of VOCs at the beginning and at the end of withering. We tentatively identify the most abundant VOCs with PTR-MS, and verify identification with SPME/GC–MS. PTR-MS allows for distinguishing (without identification) 472 peaks from withering T. jasminoides which mostly cannot be found with SPME/GC–MS. A high fragmentation of the compounds is observed. The PTR-MS data are assessed with principal component analysis and the three phases are confirmed. At the beginning, seemingly regular flower VOCs are emitted, while in the third phase of withering, alcohol emission bursts towards the end point of withering. The latter can be only detected with PTR-MS. Hence, PTR-MS and SPME/GC–MS supply complementary information. The study demonstrates the potential of applying PTR-MS together with SPME/GC–MS to time-dependent physiological living flower experiments and of T. jasminoides in particular, and suggests the possible use of PTR-MS fingerprinting for origin determination and quality assessment, and studies such as plant-plant, plant-compound (hormone), plant-animal (pollinator, herbivore) or plant-pathogen interaction
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
Volatile compound changes during shelf life of dried Boletus edulis: comparison between SPME-GC-MS and PTR-ToF-MS analysis
No full textDrying process is commonly used to allow long time storage of valuable porcini mushrooms (Boletus edulis). Although considered a stable product dried porcini flavour changes during storage. Monitoring of volatile compounds during shelf life may help to understand the nature of the observed changes. In the present work two mass spectrometric techniques were used to monitor the evolution of volatile compounds during commercial shelf life of dried porcini. Solid phase microextraction (SPME) coupled to gas chromatography - mass spectrometry (GC-MS) allowed the identification of 66 volatile compounds, 36 of which reported for the first time, monitored during the commercial shelf life of dried porcini. Proton transfer reaction - time of flight - mass spectrometry (PTR-ToF-MS) , a direct injection mass spectrometric technique, was shown to be a fast and sensitive instrument for the general monitoring of volatile compound evolution during storage of dried porcini. Furthermore, PTR-ToF-MS grants access to compounds whose determination would otherwise require lengthy pre-concentration and/or derivatization steps such as ammonia and small volatile amines.
The two techniques, both used for the first time to study dried porcini, provided detailed description of time evolution of volatile compounds during shelf life. Alcohols, aldehydes, ketones and monoterpenes diminish during the storage while carboxylic acids, pyrazines, lactones and amines increase. The storage temperature modifies the rate of the observed changes influencing the final quality of the dried porcini.
We showed the advantages of both techniques, suggesting a strategy to be adopted to follow time evolution of volatile compounds in food products during shelf life, based on the identification of compounds by GC-MS and the rapid time monitoring by PTR-ToF-MS measurements in order to maximize the advantages of both technique
Double clustering of PTR-ToF-MS data enables the mapping of QTLs related to apple fruit volatilome
No full textVolatile secondary metabolites represent major and complex components of fruit flavor and odor. However, limited information about their genetic control is available. Quantitative trait loci (QTLs) affecting fruit volatile emission are usually identified by integrating genetic and metabolic data on germplasm collections or breeding materials. Proton Transfer Reaction—Time of Fligh—Mass Spectrometry (PTR-ToF-MS) is a novel fast and high sensitivity analytical method for VOC (Volatile Organic Compound) detection. Recently we effectively employed PTR-ToF-MS for studying the genetic control of ester emission in apple, although a complete methodology allowing full potential QTL investigations is still missing. In this work, for the first time, a new double clustering data mining strategy to fruit volatilome data produced by PTR-ToF-MS was applied. We used this new methodology in order to perform a QTL mapping investigation related to apple VOCs on a full-sib apple population (‘Golden Delicious’ × ‘Scarlet’) assessed during shelf-life ripening, resulting in the identification of several QTLs located on seven chromosomes and associated mainly with ethylene, estragole, carbonyl, alcohol, ester and sesquiterpene emission. Although the proposed methodology is applied to apple VOCs, potential for analogous investigations in other fruit species is discusse
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