Theoretical study of resonant x-ray emission spectroscopy of Mn films on Ag

We report a theoretical study on resonant x-ray emission spectra (RXES) in the whole energy region of the Mn $L_{2,3}$ white lines for three prototypical Mn/Ag(001) systems: (i) a Mn impurity in Ag, (ii) an adsorbed Mn monolayer on Ag, and (iii) a thick Mn film. The calculated RXES spectra depend strongly on the excitation energy. At $L_3$ excitation, the spectra of all three systems are dominated by the elastic peak. For excitation energies around $L_2$, and between $L_3$ and $L_2$, however, most of the spectral weight comes from inelastic x-ray scattering. The line shape of these inelastic ``satellite'' structures changes considerably between the three considered Mn/Ag systems, a fact that may be attributed to changes in the bonding nature of the Mn-$d$ orbitals. The system-dependence of the RXES spectrum is thus found to be much stronger than that of the corresponding absorption spectrum. Our results suggest that RXES in the Mn $L_{2,3}$ region may be used as a sensitive probe of the local environment of Mn atoms.Comment: 9 pages, 11 figure

Modélisation mathématique, jeux sportifs et sciences sociales

Les jeux sportifs représentent des pratiques corporelles de portée sociale, propices à la mise en évidence des normes et des valeurs de leur aire culturelle d’adoption. La modélisation mathématique de leur contenu d’action met à découvert les universaux qui en expriment la logique interne par le truchement de graphes et de matrices. De façon contrôlable et souvent très éloquente, sont ainsi soulignées les représentations culturelles dont les jeux sportifs sont en partie le reflet.L’opposition que Claude Lévi-Strauss propose entre rite et jeu sportif est ici récusée, au profit d’une autre opposition entre jeu et sport. Le jeu sportif traditionnel n’est pas systématiquement assimilable à un « jeu à somme nulle » (comme c’est le cas du sport) ; il peut revêtir des logiques internes très diverses, « à somme non nulle », illustrées notamment par les jeux à compétition partageante (et non excluante) et par les jeux paradoxaux.Outdoor games embody physical activities with a social impact, capable of highlighting the norms and values of their cultural sphere of influence. A mathematical model of their content reveals universal values, whose internal logic can be expressed through graphs and matrices. Thus, in a measurable and often striking way, a cultural outlook, of which outdoor games are in part a reflection, is highlighted.The contrast between rituals and outdoor games as suggested by Claude Lévi-Strauss is challenged here, in favour of a different contrast between games and sports. Traditional games cannot be consistently put in the same category as “zero sum games”, as in the case of sport; they may assume very different sorts of “non-zero sum” internal logic, in particular epitomised by competitive (and not exclusive) games, and through paradoxical games

Modélisation dans les jeux et les sports

The role assumed by games and sports in their respective societies, can be enlightened by the analysis of their profound structure, whose invariant aspect contrast strongly with the incredible variety of the practices they give rise to. As Oulipo has shown for writings, games and sports are shaped by their system of constraints. These constraints determine structures named “universals” which are models based on an internal logic whose significant features characterize the motor action generated during the game. A detailed presentation of the basic structure of several universals is given (networks of motor communication, structure of the score interactions, scoring system…). The analysis’ interest and difficulty comes from showing the links between the universals’ properties and the striking orientations of the cultures the different games belong to. By using specific examples such as the Olympic Games, some relations between internal logic traits and cultural characteristics are presented: increasing the value of competition, the equality of opportunity, cooperation… The aim is to see if and how some dominant social representations are underlain by motor interaction situations whose simple mathematic properties can therefore prove decisive. The role assumed by games and sports in their respective societies, can be enlightened by the analysis of their profound structure, whose invariant aspect contrast strongly with the incredible variety of the practices they give rise to. As Oulipo has shown for writings, games and sports are shaped by their system of constraints. These constraints determine structures named “universals” which are models based on an internal logic whose significant features characterize the motor action generated during the game. A detailed presentation of the basic structure of several universals is given (networks of motor communication, structure of the score interactions, scoring system…). The analysis’ interest and difficulty comes from showing the links between the universals’ properties and the striking orientations of the cultures the different games belong to. By using specific examples such as the Olympic Games, some relations between internal logic traits and cultural characteristics are presented: increasing the value of competition, the equality of opportunity, cooperation… The aim is to see if and how some dominant social representations are underlain by motor interaction situations whose simple mathematic properties can therefore prove decisive.Le rôle assumé par les jeux et les sports au sein de leurs sociétés respectives, peut être éclairé par l’analyse de leurs structures profondes dont l’aspect invariant tranche face à l’immense variété des pratiques qu’ils suscitent. Tout comme l’a montré l’Oulipo pour les productions littéraires, le jeu sportif est façonné par un système de contraintes. Ces contraintes déterminent des structures appelées « universaux » ; ceux-ci sont des modèles fondés sur une logique interne dont les traits pertinents caractérisent l’action motrice engendrée par le déroulement du jeu. Une présentation détaillée de la structure élémentaire de plusieurs universaux est proposée (réseaux de communication motrice, structure des interactions de marque, système des scores…). L’intérêt et la difficulté de l’analyse sont liés à la mise en évidence recherchée entre les propriétés des universaux et les orientations marquantes de la culture d’appartenance des différents jeux. En s’appuyant sur des exemples précis, notamment sur les Jeux Olympiques, certaines correspondances entre les traits de logique interne et les caractéristiques culturelles sont présentées : valorisation de la compétition, de l’égalité des chances, de la coopération… L’objectif recherché est de voir dans quelle mesure certaines représentations sociales dominantes sont sous-tendues par des situations d’interaction motrice dont les propriétés mathématiques

Windsurfing : an extreme form of material and embodied interaction?

This paper makes reference to the development of water based board sports in the world of adventure or action games. With a specific focus on windsurfing, we use Parlebas (1999) and Warnier's (2001) theoretical interests in the praxaeology of physical learning as well as Mauss' (1935) work on techniques of the body. We also consider the implications of Csikzentimihalyi's notion of flow (1975). We argue that windsurfing equipment should not merely be seen as protection but rather as status objects through which extreme lifestyles are embodied and embodying