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Effects of environmental factors on the variability of mango quality and maturity, experimental and modelling approaches
No full textLa qualité du fruit regroupe un ensemble d’attributs, comme le calibre, la teneur en composés solubles, l’acidité et la couleur, qui varient en fonction des conditions de croissance rencontrées par le fruit pendant son développement et au cours de son murissement. Ce travail de thèse vise à déterminer, par des approches expérimentales et de modélisation, l’impact des conditions de croissance de la mangue sur les processus impliqués dans l’élaboration de sa qualité et de son murissement. Les approches expérimentales ont révélé d’importantes variations de calibre, masse sèche, et maturité entre les mangues selon leur position dans l’arbre et la charge en fruits. Nos mesures ont suggéré que la croissance des mangues est impactée par la diminution des flux de xylème causé par l’embolisation des vaisseaux conducteurs de sève. En plus des différences mesurées entre les fruits, nos résultats ont indiqué des variations de couleur de peau et de pulpe, d’acidité et de teneur en composés solubles au sein même des mangues qui s’expliquent en partie par les gradients de maturité. L’établissement d’un modèle thermodynamique a permis de montrer que les microclimats au sein de l’arbre génèrent un gradient de température au sein de la mangue qui varie en fonction de la position dans l’arbre. Il a été montré que ce gradient de température n’explique pas les variations d’acidité, de couleur de pulpe et de teneur en composés solubles au sein de la mangue. L’utilisation d’un modèle simulant la synthèse de l’éthylène dans la mangue a mis en évidence que les différences de maturité entre les mangues dans l’arbre s’expliquent davantage par les différences de disponibilité carbonée que par les différences de température. L’intégration des résultats expérimentaux dans un modèle de croissance en matière fraiche a permis de confirmer que l’embolisation des vaisseaux conducteurs de sève est à l’origine du ralentissement de croissance de la mangue. Enfin, le couplage de tous ces modèles à un modèle de croissance en matière sèche a montré que les variations de calibre, teneur en matière sèche et maturité entre les mangues ne sont pas causées par les différences de température, mais par les différences de charge en fruits, de période de floraison, de masse sèche des fruits à la fin de la division cellulaire, et de transpiration.L’approche pluridisciplinaire, i.e., physique, écophysiologique et biochimique, utilisée dans ce travail de thèse a permis d’acquérir de nouvelles connaissances sur l’élaboration de la qualité du fruit et son murissement et ouvre de nouvelles perspectives de recherche.One of the major difficulties involved in marketing fresh mango is to manage its quality. Mango quality includes several attributes such as size, total soluble solids content, acidity and color, all of which vary with growing conditions and during ripening. The aim of this thesis is to determine the impact of growing conditions on fruit quality and ripening through experimental and modeling approaches.Experimental studies have revealed that size, dry mass and maturity vary considerably between mangoes according to their position in the tree and fruit load. Measurements suggest that fruit growth is affected by the embolization of sap-conducting vessels. In addition to differences measured between mangoes, our results showed that quality attributes vary within fruits in relation to the maturity gradient.A physical model showed that climatic variations within the tree caused substantial temperature gradients within mangoes that change with the fruit position in the tree. These simulations revealed that quality differences within mangoes are not related to the temperature gradient, except for fruit color. Use of a model that simulates the biosynthetic pathway of ethylene indicated that maturity differences between mangoes are explained by differences in carbon supply and, to a much lesser extent, to differences in temperature. The integration of experimental results into a growth model revealed that the embolization of sap-conducting vessels caused the slowdown of fruit enlargement. Lastly, when all of these models were coupled to a model that simulates fruit growth in dry mass, it was demonstrated that variations in size, dry matter content and maturity between mangoes were caused by differences in fruit load, flowering time, fruit dry mass at the end of cell division and transpiration, rather than by differences in temperature.The multidisciplinary approach developed made it possible to better understand the processes involved in fruit quality and ripening and to open new areas of research
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
Appui à la modélisation de la fructification du litchi dans la province de Tamatave : mission réalisée du 16 au 22 août 2008 au Centre Technique Horticole de Tamatave, Madagascar
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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
Fonctionnement de la plante - Croissance et élaboration de la qualité du fruit chez le manguier
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