University of Avignon

About: University of Avignon is a education organization based out in Avignon, Provence-Alpes-Côte-d'Azur, France. It is known for research contribution in the topics: Population & Speaker recognition. The organization has 1526 authors who have published 3766 publications receiving 88928 citations.

Pectin Changes in Ripening Cherry Fruit

Abstract: Pectin solubilization was studied during ripening of cherry fruit. Pectic materials were isolated at specific stages during development. The proportion of alcohol-insoluble-material decreased on a fresh weight basis with ripeness, but increased per fruit. Pectic substances were divided into water-, oxalate- and acid-soluble fractions. The oxalate-and water-soluble part increased as acid-soluble components decreased. Water- and acid-soluble fractions contained many more neutral sugar residues than the oxalate-soluble fraction. Changes in individual sugars indicated the major alterations were the degradation of galactan and the absence of arabinan solubilization in acid-soluble pectic substance. Size exclusion chromatography showed absence of pectin depolymerization during ripening, indicating that fruit softening does not depend on pectin depolymerization.

Chlorophyll fluorescence, a nondestructive method to assess maturity of mango fruits (Cv. 'Cogshall') without growth conditions bias.

Abstract: The quality of ripe mango fruits depends on maturity stage at harvest, which is usually assessed by visible criteria or from estimates of the age of fruit. The present study deals with the potential of chlorophyll fluorescence as a nondestructive method to assess the degree of fruit maturity regardless of fruit growing conditions. Chlorophyll fluorescence parameters were measured along with respiration rates of fruits still attached to the tree. At the same harvest stage, based on the fruit age or the thermal time sum (degree-days) method, physical and biochemical measurements related to fruit maturity and quality were made. Shaded fruits had a significantly greener flesh color, as well as a lower fruit density and flesh dry matter content, than well-exposed fruits, showing that fruits at the top of the canopy were more mature than fruits within the canopy, which were still in a growth phase. Additionally, chlorophyll fluorescence parameters, Fo, Fm, and Fv, were significantly lower for fruits taken from the top of the canopy than for those from within the canopy. The unique relationship observed between chlorophyll fluorescence parameters and fruit maturity, estimated by internal carbon dioxide content, on fruit still attached to trees is independent of growing conditions, such as the position of the fruit in the canopy and carbohydrate supply. The chlorophyll fluorescence method evaluates maturity much more accurately than the degree-day method and, moreover, nondestructively provides values for individual fruits before harvest. (Resume d'auteur)

Epidemic Protection Over Heterogeneous Networks Using Evolutionary Poisson Games

Abstract: Malware is increasingly sophisticated and affects the wellbeing of a large population of heterogeneous and highly connected devices. The users of these devices can make strategic and dynamic decisions to choose whether or not to adopt the antivirus software, not only to secure their individual devices but also to protect the network they are part of. Motivated by the strategic behaviors of the antivirus adoption, we establish an evolutionary Poisson game framework to capture the random, dynamic, and heterogeneous interactions of agents in a holistic fashion, and design mechanisms to control their behaviors to achieve a system-wide objective. We first prove the existence and uniqueness of a mixed Nash equilibrium of the large population game and show that the equilibrium is an evolutionary stable strategy. Finally, we develop online algorithms using the techniques of stochastic approximation coupled with the population dynamics, and they are shown to converge to the optimal solution of the controller problem. Numerical examples are used to illustrate and corroborate our results.

Inhibition of the metmyoglobin-induced peroxidation of linoleic acid by dietary antioxidants: Action in the aqueous vs. lipid phase.

Abstract: The gastric digestion of food containing oxidizable lipids and iron catalysts for peroxide decomposition such as (met)myoglobin from muscle meat can be accompanied by an extensive formation of potentially toxic lipid hydroperoxides. An early protective action by dietary antioxidants in the gastro-intestinal tract is plausible, especially for poorly bioavailable antioxidants such as polyphenols. Hence, the ability of antioxidants to inhibit lipid peroxidation initiated by dietary iron in mildly acidic emulsions is a valuable and general model. In this work, the ability of some ubiquitous dietary antioxidants representative of the main antioxidant classes (α-tocopherol, the flavonol quercetin, β-carotene) to inhibit the metmyoglobin-induced peroxidation of linoleic acid is investigated by UV–visible spectroscopy and HPLC in mildly acidic emulsions. The phenolic antioxidants quercetin and α-tocopherol come up as the most efficient peroxidation inhibitors. Inhibition by quercetin essentially proceeds in the a...