1,720,954 research outputs found
Différenciation du sirop d'érable à défaut de saveur de type bourgeon (√R5) du sirop d'érable à saveur sans défaut (REG) à l'aide de SPME-GC/MS et UPLC-QTOF-MS/MS
Full text linkL’industrie des produits de l’érable est particulièrement importante en Amérique du Nord. Elle est touchée par un phénomène naturel qui se produit en fin de saison de récolte. Il s’agit de l’altération du goût du sirop ; un goût fort désagréable se développe et se nomme goût de bourgeon vu qu’il coïncide au bourgeonnement des feuilles d’érable. Des coûts et du temps sont impliqués à sa récolte et sa production.
Cependant, un sirop d’érable avec un goût de bourgeon est vendu à moindre prix. Il constitue donc une perte potentielle d'argent pour les producteurs. Au fil du temps, ils ont appris à se fier à des signes distincts de la nature pour déterminer le début du bourgeonnement. Néanmoins, il est important de le détecter hâtivement pour les producteurs et de mieux comprendre les changements moléculaires associés au défaut de saveur de type bourgeon.
Plusieurs travaux sur les produits de l’érable ont été effectués durant le dernier siècle, mais ce n’est que récemment que des projets de recherche sont centrés sur le goût de bourgeon. La détection de celui-ci est certes importante, mais il y est aussi question de mieux connaître la variation de la composition du sirop ou de la sève d’érable, afin de mieux comprendre le phénomène. Tel que décrit dans l’introduction de ce
mémoire, on connaît maintenant mieux la composition du sirop d’érable, même que quelques solutions ont été proposées à notre problème, mais beaucoup de questions restent sans réponse que ce mémoire tentera de résoudre.
C'est dans ce contexte que cette étude se pose. En visant à identifier les molécules responsables du défaut de goût de type bourgeon que l’on peut retrouver dans le sirop d’érable, nous espérons aider à mieux cibler le problème et à mieux comprendre le métabolisme et, éventuellement, comprendre comment ce goût se développe. Dans un second temps, la découverte de molécules pas encore rapportées, au meilleur de notre connaissance, comme étant présentes dans le sirop d’érable est aussi visée, sans égard à la classification du sirop. Les travaux de ce mémoire contribueront, ultimement, à trouver une façon d’empêcher la formation de ce goût et surtout un moyen de l’éliminer.
Pour ce, une première partie correspondant à l’analyse des composés volatils a été effectuée par SPME et GC-MS sur 78 échantillons de sirop d’érable. L’analyse statistique des résultats par PCA cible 42 composés et associe chacun d’entre eux au sirop d’érable avec le défaut de saveur ou alors au sirop sans défaut de saveur. Parmi elles, seules 36 ont pu être identifiées par leurs spectres de masse.
La seconde partie correspond à l’analyse des composés non volatils par UPLC-QTOF et UPLCMS/MS. La méthode a été optimisée pour cibler les molécules relativement apolaires par rapport aux sucres et aux acides aminés présents dans le sirop d’érable. Au total, 20 échantillons de sirop ont été analysés, dont 10 à défaut de saveurs de type bourgeon et 10 sans défaut. Pour cette partie, l’analyse de composantes principales a encore une fois été utilisée pour classer les types de sirop à l’étude selon les composés détectés.
Ainsi, le mémoire avance les connaissances moléculaires liées à l’émergence du défaut de bourgeon dans le sirop d’érable.The maple products industry is particularly important in North America. It is affected by a natural phenomenon that occurs at the end of the harvest season. It’s the alteration of the taste of the syrup; a very unpleasant taste develops and is called buddy flavour since it coincides with the budding of maple leaves. Costs and time are involved in its harvest and production. When maple syrup is associated with the buddy taste, its commercial value is lower. Therefore, it contributes to a loss of money for producers. Over time, they have learned to rely on distinct signs from nature to determine the onset of budding. However, methods are needed to detect it and research is needed to better understand the molecular changes in maple syrups.
Several research projects on maple products have been carried out during the last century, but it is only recently that research projects have focused on the buddy flavour. They focus on determining the variation in the composition of maple syrup or sap, but also on better understanding of the phenomenon. We now know more than ever about the composition of maple syrup, on top of that some solutions have been proposed to our problem, but many questions remain unanswered and it is obvious that there is still so much to discover.
It is in this context that this study arises. By aiming to identify the molecules responsible for the buddy flavour defects that can be found in maple syrup, we hope to help on targeting the problem and better understanding the metabolism of maple trees and, eventually, how the buddy taste develops. Secondly, it is aimed at discovering molecules not yet reported, to the best of our knowledge, as being present in maple syrup regardless of the classification of the syrup. This will contribute, ultimately, in finding a way to prevent the formation of this taste and a way to eliminate it.
Thus, the first part of this master’s thesis corresponds to the analysis of volatile compounds by SPME and GC-MS on 78 maple syrup samples. Statistical analysis of the results targets 42 compounds and associates them with either maple syrup with flavour defects or with maple syrup with regular flavour maple syrup. Among these, 36 molecules could be identified by mass spectrometry. To extract correlations from our data, the principal component analysis (PCA) ensued.
The second part corresponds to the analysis of non-volatile compounds by UPLC QTOF and UPLC-MS/MS. The method has been optimized to target molecules that are relatively apolar compared to sugars and most of the amino acids present in maple syrup. A total of 20 syrup samples were analyzed, including 10 with bud-like flavour defects and 10 with no defects. For both parts, PCA was once again used to determine which types of syrup under study are the compounds associated with. Taken together, the results presented in this master’s thesis advances knowledge on the molecular origins of the buddy flavour defect in maple syrups
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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