1,720,962 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
Untargeted lipidomic profiling of grapes highlights the importance of modified lipid species beyond the traditional compound classes
No full textThe aim of this paper is to provide a detailed characterisation of grape lipidome. To achieve this objective, it starts by describing a pipeline implemented in R software to allow the semi-automatic annotation of the detected lipid species. It also provides an extensive description of the different properties of each molecule (such as retention time dependencies, mass accuracy, adduct formation and fragmentation patterns), which allowed the annotations to be made more accurately. Most annotated lipids in the grape samples were (lyso)glycerophospholipids and glycerolipids, although a few free fatty acids, hydroxyceramides and sitosterol esters were also observed. The proposed pipeline also allowed the identification of a series of methylated glycerophosphates never previously observed in grapes. The current results highlight the importance of expanding chemical analyses beyond the classical lipid categories
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
Untargeted lipidomic profiling of grapes highlights the importance of modified lipid species beyond the traditional compound classes
No full textThe aim of this paper is to provide a detailed characterisation of grape lipidome. To achieve this objective, it starts by describing a pipeline implemented in R software to allow the semi-automatic annotation of the detected lipid species. It also provides an extensive description of the different properties of each molecule (such as retention time dependencies, mass accuracy, adduct formation and fragmentation patterns), which allowed the annotations to be made more accurately. Most annotated lipids in the grape samples were (lyso)glycerophospholipids and glycerolipids, although a few free fatty acids, hydroxyceramides and sitosterol esters were also observed. The proposed pipeline also allowed the identification of a series of methylated glycerophosphates never previously observed in grapes. The current results highlight the importance of expanding chemical analyses beyond the classical lipid categories
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 grape harvest time on the metabolomic profile of Ribolla Gialla monovarietal sparkling wines
No full textAIM: The timing of grape harvest is crucial factor to be considered in the winemaking process, as delayed harvest increases the content of varietal aromas, esters, aldehydes, and alcohols, while concentration of green odor related compounds decreases [1,2]. In order to target optimal grape ripeness and maximize positive attributes of Ribolla Gialla sparkling wine, an experiment with three different harvest dates was established to determine whether an extended harvest might lead to an increase of important odor-impact compounds, and possibly improve wine sensory profile. METHODS: The harvest timing trial was examined across three consecutive seasons in Friuli Venezia Giulia region, Italy, where the first harvest was set when a minimum compromise was reached between the accumulation of sugars and the level of titratable acidity of the grapes. The second and third harvests were separated by a maximum of seven days, depending on meteorological conditions. In addition to sensory evaluation, a multitargeted metabolomics approach was applied for chemical characterization of wine samples, focusing on volatile compounds, lipid substances, and aromatic amino acid metabolites.RESULTS: As far as the composition in volatile compounds is concerned, the results have shown a significant advantage in the transition from first to the second harvest time, which resulted in enhanced production of esters, while in certain cases, the additional third harvest caused the increase of acetic acid and other volatile fatty acids. The lipid composition was not affected by the harvest time; however, the lipid content varied depending on the seasonal factor. Concerning tryptophan metabolites, it has been clearly shown that the extension of harvest date was not necessarily correlated with the formation of untypical aging substances that could compromise the quality of sparkling wines. Lastly, the sensory analysis revealed that the highest scores for preference were assigned to the wines from the second harvest. These samples were associated with ‘floral’ and ‘tropical’ descriptors, which appeared to be in accordance with the chemical analysis. CONCLUSIONS: The presented results indicate significant and coherent modulations of wine aroma profile in relation to grape harvest date. Therefore, this study could represent a great practical feedback for winegrowers, in order to determine the optimal harvest time
Grape lipidomics: An extensive profiling thorough uhplc–ms/ms method
Full text linkLipids play many essential roles in living organisms, which accounts for the great diversity of these amphiphilic molecules within the individual lipid classes, while their composition depends on intrinsic and extrinsic factors. Recent developments in mass spectrometric methods have significantly contributed to the widespread application of the liquid chromatography‐mass spectrometry (LC–MS) approach to the analysis of plant lipids. However, only a few investigators have studied the extensive composition of grape lipids. The present work describes the development of an ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) method that includes 8098 MRM; the method has been validated using a reference sample of grapes at maturity with a successful analysis and semi‐quantification of 412 compounds. The aforementioned method was subsequently applied also to the analysis of the lipid profile variation during the Ribolla Gialla cv. grape maturation process. The partial least squares (PLS) regression model fitted to our experimental data showed that a higher proportion of certain glycerophospholipids (i.e., glycerophosphoethanolamines, PE and glycerophosphoglycerols, PG) and of some hydrolysates from those groups (i.e., lyso‐glycerophosphocholines, LPC and lysoglycerophosphoethanolamines, LPE) can be positively associated with the increasing °Brix rate, while a negative association was found for ceramides (CER) and galactolipids digalactosyldiacylglycerols (DGDG). The validated method has proven to be robust and informative for profiling grape lipids, with the possibility of application to other studies and matrices
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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