Abstract:
Despite the current evolution of several tools that help understanding, representing and constructing a better awareness of sound and more generally the sensory qualities of the built environment, the integration of sonic dimension in the ordinary architectural production remains difficult. Sonic dimension is still undervalued considered as an accessory or as a second dimension of the space. Till now, the sonic quality doesn’t have its legitimacy in the architectural and urban thinking except in specific situations where designer should solve certain problems of noise and propagation. Therefore, we should find the appropriate qualitative criteria of the architectural elements that don’t only integrate the perceptive aspects but also the action. In this sense, we shall present an experimentation that has been elaborated to clarify the relationship between sound and movement or sound and action in order to design spatial architectural elements. How can we identify the sonic role during the spatial experiment and explore the different corporal and movement modalities that emerge by hearing? We postulate that the actions potentials that emerge in a sonic context must be considered as an alternative that can modulate the environment in space and time[1]. [1] This paper is based on another article : Approche écologique de kinesthèses sonores : expérimentation d'un prototype d'abri public et ergonomie acoustique, Acoustique et techniques, n° 41, 2005, pp. 24-31

Abstract:
These notes are an introduction to a few selected theoretical ideas in the field of quantum spin liquids: classical zero modes and breakdown of the 1/S expansion, the Lieb-Schultz-Mattis-Hastings theorem and Oshikawa's argument, the short-ranged resonating valence-bond picture, large-N limit (Schwinger bosons) and Z_2 gauge theory.

Abstract:
Let $Q$ be an acyclic quiver. We introduce the notion of generic variables for the coefficient-free acyclic cluster algebra $\mathcal A(Q)$. We prove that the set $\mathcal G(Q)$ of generic variables contains naturally the set $\mathcal M(Q)$ of cluster monomials in $\mathcal A(Q)$ and that these two sets coincide if and only if $Q$ is a Dynkin quiver. We establish multiplicative properties of these generic variables analogous to multiplicative properties of Lusztig's dual semicanonical basis. This allows to compute explicitly the generic variables when $Q$ is a quiver of affine type. When $Q$ is the Kronecker quiver, the set $\mathcal G(Q)$ is a $\mathbb Z$-basis of $\mathcal A(Q)$ and this basis is compared to Sherman-Zelevinsky and Caldero-Zelevinsky bases.

Abstract:
Building on the results of Ma, Trudinger and Wang \cite{MTW}, and of the author \cite{L5}, we study two problems of optimal transportation on the sphere: the first corresponds to the cost function $d^2(x,y)$, where $d(\cdot,\cdot)$ is the Riemannian distance of the round sphere; the second corresponds to the cost function $-\log|x-y|$, it is known as the reflector antenna problem. We show that in both cases, the {\em cost-sectional curvature} is uniformly positive, and establish the geometrical properties so that the results of \cite{L5} and \cite{MTW} can apply: global smooth solutions exist for arbitrary smooth positive data and optimal maps are H\"older continuous under weak assumptions on the data.

Abstract:
Sherman-Zelevinsky and Cerulli constructed canonically positive bases in cluster algebras associated to affine quivers having at most three vertices. Both constructions involve cluster monomials and normalized Chebyshev polynomials of the first kind evaluated at a certain "imaginary" element in the cluster algebra. Using this combinatorial description, it is possible to define for any affine quiver $Q$ a set $\mathcal B(Q)$ which is conjectured to be the canonically positive basis of the acyclic cluster algebra $\mathcal A(Q)$. In this article, we provide a geometric realization of the elements in $\mathcal B(Q)$ in terms of the representation theory of $Q$. This is done by introducing an analogue of the Caldero-Chapoton cluster character where the usual quiver Grassmannian is replaced by a constructible subset called transverse quiver Grassmannian.

Abstract:
Since the end of the 1980's, the development of self-driven autonomous vehicles is an intensive research area in most major industrial countries. Positive socio-economic potential impacts include a decrease of crashes, a reduction of travel times, energy efficiency improvements, and a reduced need of costly physical infrastructure. Some form of vehicle-to-vehicle and/or vehicle-to-infrastructure cooperation is required to ensure a safe and efficient global transportation system. This thesis deals with a particular form of cooperation by studying the problem of coordinating multiple mobile robots at an intersection area. Most of coordination systems proposed in previous work consist in planning a trajectory and to control the robots along the planned trajectory: that is the plan-as-program paradigm where planning is considered as a generative mechanism of action. The approach of the thesis is to plan priorities -- the relative order of robots to go through the intersection -- which is much weaker as many trajectories respect the same priorities. More precisely, priorities encode the homotopy classes of solutions to the coordination problem. Priority assignment is equivalent to the choice of some homotopy class to solve the coordination problem instead of a particular trajectory. Once priorities are assigned, robots are controlled through a control law preserving the assigned priorities, i.e., ensuring the described trajectory belongs to the chosen homotopy class. It results in a more robust coordination system -- able to handle a large class of unexpected events in a reactive manner -- particularly well adapted for an application to the coordination of autonomous vehicles at intersections where cars, public transport and pedestrians share the road.

Abstract:
We propose a few variations around a simple model in order to take into account the market impact of the option seller when hedging an option. This "retro-action" mechanism turns the linear Black and Scholes PDE into a non-linear one. This model allows also to retrieve some earlier results of \cite{CheriSonTouz}. Numerical simulations are then performed.

Abstract:
Background Accurate hospital costs are required for policy-makers, hospital managers and clinicians to improve efficiency and transparency. However, different methods are used to allocate direct costs, and their agreement is poorly understood. The aim of this study was to assess the agreement between bottom-up and top-down unit costs of a large sample of surgical operations in a French tertiary centre. Methods Two thousand one hundred and thirty consecutive procedures performed between January and October 2010 were analysed. Top-down costs were based on pre-determined weights, while bottom-up costs were calculated through an activity-based costing (ABC) model. The agreement was assessed using correlation coefficients and the Bland and Altman method. Variables associated with the difference between methods were identified with bivariate and multivariate linear regressions. Results The correlation coefficient amounted to 0.73 (95%CI: 0.72; 0.76). The overall agreement between methods was poor. In a multivariate analysis, the cost difference was independently associated with age (Beta = ？2.4; p = 0.02), ASA score (Beta = 76.3; p<0.001), RCI (Beta = 5.5; p<0.001), staffing level (Beta = 437.0; p<0.001) and intervention duration (Beta = ？10.5; p<0.001). Conclusions The ability of the current method to provide relevant information to managers, clinicians and payers is questionable. As in other European countries, a shift towards time-driven activity-based costing should be advocated.