Mise au point d’un atlas en ligne d’images tomodensitométriques normales de l’iguane vert (iguana iguana) et sa mise en ligne

La médecine des Nouveaux Animaux de Compagnie connait désormais un important essor, aussi bien d’un point de vue de l’enseignement dans les écoles vétérinaires, que de par l’augmentation de cette part de clientèle dans la pratique en cabinet. Associé à cela, il devient important de pouvoir avoir recours à des examens complémentaires de qualité afin de poser un diagnostic exact. L’imagerie est un outil très pratique, de plus en plus facilement accessible. C’est entre autre le cas de l’examen tomodensitométrique. Cependant, son développement et son utilisation récente en médecine vétérinaire rendent l’interprétation de ces clichés délicats. Difficulté qui est d’autant plus marquée lorsqu’il s’agit d’examens réalisés sur des NAC, et notamment sur des reptiles. Le but de cette thèse est donc d’offrir un atlas d’images tomodensitométriques légendées d’un iguane vert en bonne santé, en coupe sagittale et transversale, afin de pouvoir servir de support à l’interprétation d’images pathologiques lors d’un diagnostic. Les images présentées ont été acquis à travers trois fenêtres distinctes : l’une osseuse, l’autre pulmonaire et une parenchymateuse. Etant librement accessible en ligne, il pourra aussi bien être consulté par des étudiants, que par des professionnels en fonction ou toute autre personne intéressée. Cette étude présente dans un premier temps les principes physiques de la tomodensitométrie et la réalisation pratique d'un examen scanner. La seconde partie s’articule autour de la présentation du modèle biologique utilisé, soit un Iguane vert. Enfin, la troisième et dernière partie présente la création de l’atlas

Numerical simulation of thin shear driven films

Aircraft icing is an important concern in aviation safety. Improvements in the computational models of ice accretion are an important step in improving safety in icing conditions. One of the improvements necessary for these models is a better understanding of surface water transport and its role in the ice accretion process. Changes in water mass flux can alter the shape and location of larger scale ice growth, thereby affecting the aerodynamics of the airfoil. While past analyses have assumed a Couette flow in the film and ignored surface waves, more recent research has begun to look at the effect of these interfacial waves. These studies have found that the mass flux can, in some cases, be greatly increased by these surface processes. This study examines the effect of droplet impingement on thin water films to assess any impact on overall interfacial wave structure and mass transport. The theory is first developed, without including droplet impingement, to describe the limit as water film thickness goes to zero. In this limit the air shear stress becomes the dominant driving force behind interfacial wave development, and the governing equations can be simplified to a single modified Kuramoto-Sivashinsky equation. To model the droplet impact, a backward time singularity of the film equation was found, which is expected to be consistent with vertically impacting droplets. It was found that there are realistic droplet volume and frequency combinations which result in significantly increased mass flux within the film. The results of this study also suggest that there are larger scale disturbances triggered by the droplets which require further consideration

Vigilance: a process contributing to the resilience of organizations

Available on: http://www.resilience-engineering.org/REPapers/Brizon_Wybo.pdfInternational audienceFrom the analysis of emergency management activities, four main processes can be identified that contribute to the resilience of an organization facing a hazardous situation: Prevention, Protection, Learning and Vigilance. Vigilance is the ability of a system to detect and interpret weak signals and alerts. By doing so, it develops its anticipation capacities. We define two types of vigilance: individual and organizational. First one is required to run safely a system, but is difficult to set up. The second one permits to avoid crisis. After that we expose an organization of vigilance in three times: 1. Instantaneous danger, 2. Non instantaneous but known danger, 3. Unknown danger. But being vigilant requires access to information. We define three barriers that weaken vigilance: A contextual barrier, an interest (or routine) barrier and a communication barrier. Finally, we propose rules to promote a vigilant behavior and to organize vigilance in a system

Better the devil you know: evidence from the UK mobile market

Do firms strategically confuse their customers? Using a detailed dataset covering virtually all mobile phone tariffs and their handsets in the UK between January 2010 and September 2012, we examine the co-evolution of prices with the differentiation and overlap of operators' product portfolios. Incorporating the fact that mobile tariffs are multidimensional and hard to compare but easy to imitate and cheap to launch, we argue that firms introduced a large number of dominated tariffs as an obfuscation strategy. We show that the increase in dominated tariffs correlates with the increase in average prices despite converging product portfolios. This exploratory study is one of the first to offer suggestive evidence of the existence and role of obfuscation as a firm strategy

When oligopolies confuse consumers, beware the rise of confusopoly

Confusing consumers can be profitable for companies, in particular in a competitive market where they can hardly increase their prices without losing their consumers. Ambre Nicolle, Christos Genakos, and Tobias Kretschmer study the UK mobile telecommunications market before the introduction of 4G services – and find evidence that mobile operators decreased the transparency of their mobile plans, creating confusion to consumers and at the same time successfully managed to increase prices