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Gas chromatography/mass spectroscopy analysis (GC/MS) of essential oils obtained from populations of the resurrection plant Myrothamnus moschatus, growing in different areas of Madagascar, allowed identification of three main chemotypes in the species. The first one was provided by plants with a high content of trans-pinocarveol and pinocarvone; the second one involved plants with high percentages of limonene, cis- and trans-p-mentha-1(7),8-dien-2-ol, and β-selinene; and the third chemotype was characterized by plants with high levels of oxygenated sesquiterpenes such as caryophyllene oxide and α- and β-isomers of caryophylla-4(12),8(13)-dien-5-ol. Chemical data were supported by chemometric technique as the principal component analysis. Furthermore, the relationship between the dioecy and phytochemistry within one population was also considered. Finally, correlations between chemical variations and ethnobotanical data were assessed.

This paper analyzes the productivity of a robotic production cell, functioning under a repetitive robot move cycle. The cell is composed of m machines and one or several robot arms. Identical or different parts are entering the cell during a robot cycle. The problem of cycle time evaluation is shown to be an instance of the basic cyclic scheduling problem. Thus, se^-cral po^verful results previously developed in the cyclic scheduling context are used to analjfze our problem. We propose a O{q • m^) algorithm to compute the cycle time. The algorithm is first introduced for one-robot cells and then extended to multi-robot cells. A djTiamic programming algorithm is used to find the optimal robot move cycle, that is, the cycle with minimum cycle time. Numerical results highlight the efRciencj' of cycle time evuluation methods and their potential practical utility in finding the optimal robot move cycle. :Keywords: Robotic production Cell, Cyclic scheduling. Minimum cycle time. Critical Circuit, Maximum ratio cycle problem. Longest path algorithm. Optimal Robot Move Cycle.Nous analysons la productivite d'unc cellule de production robotisec, dans laquelle les deplacemcnts du robot de transport ont un caractere cyclique. Pour une cellule quelconque a m machines, pour des pieces identiques ou differentes, nous montrons que le probleme de devaluation du temps de cycle est une instance de la version cyclique du probleme central de rordonnancement. Plusieurs resultats puissants issus de la theoric de l'ordonnancement cyclique sont utilises. Nous proposons un algorithme polynomial detaille base sur la recherche du plus long chemin dans un graphe pour calculer le temps de cycle minimum, de complexite 0{q-m^). Les resultats introduits pour un seul robot sont ensuite ^tendus a des cellules multi-robots. Un algorithme de programmation dynamique est utilise pour trouver le cycle optimal de mouvement du robot. Les r&ultats numeriques demontrent Texcellente performance des methodes d'e\'aluation du temps de cycle proposees ainsi que leur potentiel pour la recherche de l'ordonnancxjment optimal du robot.Mots Clefs : Cellule de production robotisee, Ordonnancement cyclique. Temps de cycle minimum, Algorithme de plus long chemin. Circuit critique, Probleme du ratio maximum, Ordonnaneement optimal du robot.

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This two-day conference, whose topic expands on the Agrégation externe d'anglais curriculum, was organized by Hervé Mayer (EMMA, EA741,