Limites politiques oubliées : Armorique et Bretagne - Critique de sources.

International audienceAre Armorica and Britain they true or false synonyms ? The geography of the Armorican military confederations, as described by Caesar, seems to show its influence under the late Roman Empire, until the advent of Pepin the Short and recovers its unity with the sphere Plantagenet. The root of such a unity should it be sought in the epic story of Maxime and his "gift of the earth" to his legions of Britain? The migration of saints from "Britanny" in Carolingian Gaul seem to confirm such an hypothesis.Armorique et Bretagne sont ils de faux synonymes ? La géographie des confédérations militaires armoricaines semble monter son influence sous l'Empire romain tardif, jusqu'à l'avènement de Pépin-Le-Bref et retrouve son unité dans le domaine Plantagenêt. La racine d'une telle unité doit-elle être recherché ans l'épopée de Maxime et son "don de la terre" à ses légions de Bretagne ? Les migrations des saints "bretons" en Gaule carolingienne semblent en confirmer l'hypothèse

The Price of Connectivity for Vertex Cover

The vertex cover number of a graph is the minimum number of vertices that are needed to cover all edges. When those vertices are further required to induce a connected subgraph, the corresponding number is called the connected vertex cover number, and is always greater or equal to the vertex cover number. Connected vertex covers are found in many applications, and the relationship between those two graph invariants is therefore a natural question to investigate. For that purpose, we introduce the {\em Price of Connectivity}, defined as the ratio between the two vertex cover numbers. We prove that the price of connectivity is at most 2 for arbitrary graphs. We further consider graph classes in which the price of connectivity of every induced subgraph is bounded by some real number $t$. We obtain forbidden induced subgraph characterizations for every real value $t \leq 3/2$. We also investigate critical graphs for this property, namely, graphs whose price of connectivity is strictly greater than that of any proper induced subgraph. Those are the only graphs that can appear in a forbidden subgraph characterization for the hereditary property of having a price of connectivity at most $t$. In particular, we completely characterize the critical graphs that are also chordal. Finally, we also consider the question of computing the price of connectivity of a given graph. Unsurprisingly, the decision version of this question is NP-hard. In fact, we show that it is even complete for the class $\Theta_2^P = P^{NP[\log]}$, the class of decision problems that can be solved in polynomial time, provided we can make $O(\log n)$ queries to an NP-oracle. This paves the way for a thorough investigation of the complexity of problems involving ratios of graph invariants.Comment: 19 pages, 8 figure

Navigating the future: Building adaptive capacity in international schools

Given the pace and complexity of change for schools globally, this study investigates how leaders of international schools are navigating the future for the organisations they lead. The research draws on two pieces of existing literature, firstly that of Adaptive Leadership Theory which has mainly evolved outside the education sector and secondly literature related to the School as a Learning Organisation (SLO) which has not specifically been defined within the international school context. This study explores how relevant and applicable these two concepts are for international schools and investigates what the relationship is between the two concepts. This study is qualitative, using eleven semi-structured interviews with educational leaders working in the international school sector. The participants within this study defined, with a strong degree of consistency, their view of schools as adaptive organisations and of adaptive leadership, identifying three overarching themes: openness, strong sense of identity and empowerment. Participants also defined a set of adaptive leadership behaviours which they viewed as essential for growing adaptive capacity in international school leaders. From the data analysed within this study, the SLO concept is relevant and applicable to an international school context. This research contributes to a gap in the knowledge base relating to adaptivity in the education context, specifically in relation to international schools. Detail is provided on the characteristics of an adaptive international school and adaptive international school leadership. The research provides confidence for the applicability of the SLO model in international schools and defines the interrelationship between this and the concept of adaptivity

Calorimetric study of the heat effects induced by the fixation of hydrogen sulphide on the surface of modified activated carbon fibres

6 pagesIn order to improve their efficiency for the removal of H2S contained in polluted effluents, activated carbon fibres are impregnated by KOH aqueous solutions. In presence of water vapour, H2S is not simply physically adsorbed on the surface of the treated cloths but several reactions can occur. The fixation mechanism proposed has been validated and completed through the calorimetric study of the heat effects induced by the reactions that occur when the treated fibres are in contact with a gas mixture of H2O and H2S

Fragmentation de grains de sable. Suivi par émission acoustique et bilans de population.

6 pagesDevenue très courante dans le domaine du contrôle non destructif, l'étude des ondes acoustiques est beaucoup moins utilisée pour suivre l'évolution de certains phénomènes. Pourtant elle peut se révéler utile, notamment pour caractériser les phénomènes intervenant lors de la compression des poudres. L'analyse de l'émission acoustique (E.A.) au cours de la compression de plusieurs poudres pharmaceutiques telles que l'aspirine, l'amidon, le saccharose et le kétoprofène a permis de mieux cerner les phénomènes qui se produisent pendant la formation du comprimé [1,2]. Les ondes acoustiques émises par la poudre dépendent des phénomènes se produisant pendant la compression, tels que le réarrangement granulaire, la fragmentation et la déformation plastique des grains. Serris [1,2] a également remarqué que l'intensité de l'émission acoustique est fonction de la poudre. L'émission d'ondes acoustiques peut alors être considérée comme une caractéristique intrinsèque d'une poudre

Influence of temperature on the compaction of an organic powder and the mechanical strength of tablets.

International audienceThe purpose of this work consists in following the dependence of physical properties on the temperature during the compaction of an organic component. A special thermo-regulated die has been developed to realize uniaxial compression at different constant temperatures. This study has shown that a temperature change modifies the microstructures and the mechanical behaviour of the tablets. The measurement of the tablet porosity during the compression cycle allows us to conclude that temperature influences mainly the phenomena occurring during the isobaric stage of the compression cycle and not the ones during the pressure increase. On the other hand, during the pressure increase, the acoustical activity of the powder is reduced when temperature increases. The tensile strength of tablets realized at different temperatures was also studied and shows a maximum around 60°C that can be explained by the SEM analysis of the microstructure of the tablets

Les partis politiques en France : des organismes de droit privé ?

Il n’existe pas de définition légale des partis politiques, libres de se créer et d’agir comme ils le souhaitent. Au sens juridique du terme, les partis sont des organisations de droit privé. Les rapports entre leurs membres, la désignation de leurs dirigeants, les investitures électorales relèvent de la réglementation sur les associations et donc de la compétence du juge judiciaire. Ils n’exercent pas de mission de service public. Seule leur participation à la vie politique permet à la loi de les assujettir au respect de l’ordre démocratique et de la légalité de leur action, sous le contrôle du juge administratif.There is no legal definition for political parties, they can be created and act as they wish. In the legal sense of the term, parties are private-law bodies. The relations between their members, the designation of their leaders, their electoral appointments are governed by the rules and regulations concerning associations and therefore a matter for a legal judge. They do not have a mandate for public service. Their participation in political life alone is sufficient to make them subject to the law in respect of democratic order and the legality of their acts, under the supervision of an administrative judge

Etude de l'influence de la température sur la compressibilité et la résistance à la rupture de matériaux granulaires

9 pagesLes poudres sont couramment utilisées sous forme de comprimés. Le comportement de ces poudres est sensible à différents paramètres tels que la température et l'humidité. La plupart des études de comportement ont porté sur l'influence des paramètres contrôlant la compression mais très rarement sur l'influence des paramètres extérieurs. Aussi avons nous choisi d'étudier l'influence de la température au cours du cycle de compression sur la compressibilité et sur les caractéristiques finales des comprimés obtenus à partir d'un composé organique fixé. Des expériences ont été réalisées avec une presse uniaxiale LLOYDS. Un système de chauffage et de régulation en température a été adapté sur des matrices de compression uniaxiale. Un suivi de la porosité et des émissions acoustiques en cours de compression a été réalisé. Les relations de ces caractéristiques avec les mesures de la résistance à la rupture et l'évolution des microstructures des comprimés obtenus sont discutées

Influence of temperature on the compaction and the mechanical strength of an organicpowder

6 pagesClassical works made on powder compaction have been developing studies of parameters like the maximum pressure reached, the punch velocity, the duration of isobaric stage, on tablets properties. But the influence of temperature during the compression has been neglected in most cases. Now, most of pharmaceutical and chemical products, in particular organic products, are sensitive to temperature. In this work, the role of temperature on the compressibility of an organic powder commonly used in the industry has been examined. The consequences on the structure and on the mechanical behaviour of the tablets have been studied. The evolution of the porosity, the tablet strength and the fracture aspects have been followed and then analysed during and after the compression