1,721,016 research outputs found
Use of ATR-FTIR Microspectroscopy to Monitor Autolysis of Saccharomyces cerevisiae Cells in a Base Wine
No full textIn this study, we evaluated the potentialities of ATR-FTIR microspectroscopy coupled to PCA in monitoring the major biochemical changes that occur during the autolysis of yeasts used for sparkling wine production. For this purpose, mid-infrared measurements were made on cells of the model strain Saccharomyces cerevisiae EC1118 in the course of autolysis induced at 30 °C for five days in a model and in a base wine. By relating principal component loadings to the corresponding absorption bands, it was shown that they well describe compositional modifications induced by autolytic process on yeast cells, such as partial hydrolysis of proteins, increase of peptides, free nucleotides, lipids, mannans, and β-1,3 glucans. The corresponding score−score plots allowed us to monitor the different kinetics and to distinguish among faster, intermediate, and slower processes. ATR-FTIR microspectroscopy coupled with PCA is proposed as a sensitive method that can provide useful information to select efficient yeast strains, capable of accelerated autolysis, to be used in the second fermentation and aging of sparkling wines
Lactobacillus casei group effective identification
No full textLactobacillus casei, L. paracasei and L. rhamnosus form a closely related taxonomic group (Lactobacillus casei-group) within the facultatively heterofermentative lactobacilli. Some strains belonging to these species have been used for a long time as probiotics in a wide range of different products, and they commonly represent the dominant species of nonstarter lactic acid bacteria in ripened cheeses, where they contribute to flavor development.
The close genetic relationship among L. casei-group species, and the related starter cultures, hinders the development of an adequate selective identification method useful to understand the role played by each microbial population in the matrix and the routine biochemical tests often fail to discriminate among closely related species occurring in the same ecological environments, like inside ripened cheeses.
The aim of this study was a comprehensive analysis of 75 cheese isolates previously identified as L. casei group, combining the results of multiple approaches. Alternative proposed culture media for Lb. casei- group strains selective growth were tested, giving poor discrimination among strains. Futhermore, a species-specific PCR based on existing primers designed on the 16s rDNA was adapted to laboratory conditions and tested on the isolated strains. This approach allowed the identification of the majority of the tested strains, but still leaving some strains with an uncertain identity. These isolates had to be checked with more than one primer pair in order to avoid misidentification due to possible cross-reactions. Finally, a new species-specific multiplex PCR assay was developed using primers designed on a universal protein encoding gene. The amplicon size was able to rapidly distinguish L. casei, L. paracasei and L. rhamnosus strains
Applicazione della microspettroscopia FT-IR allo studio del processo autolitico in Saccharomyces cerevisiae
No full textValutazione dell’influenza dei ceppi di lievito sul profilo aromatico del Vin Santo di Gambellara mediante PTR-MS e analisi statistica multivariata
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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
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