In this talk I will discuss about the computation of correlation funcions in the AdS_3-WZNW model using the Coulomb gas method and the emergence of Selberg-type integrals. I will focuse on four-point amplitudes either preserving or violating spectral flow number conservation. The analytical continuation of factorized expressions for these correlators will be examined.

Although entirely unphysical, a generalized understanding of the random packing of spheres in high dimensions could shed light on the low dimensional case. By separating the general effects from the idiosyncratic at each dimension it may be possible to uncover simple principles which are masked in dimensions two and three. Towards this end, I report on a newly developed, highly efficient, GPU-based simulation package with which to effect the packing of polydisperse spheres in arbitrary dimensions. I further report on a newly developed analysis technique with which to efficiently characterize high dimensional packings by the additively weighted Voronoi tesselation. Using these techniques we explore the structure of packings in several arenas: 1) we test the assumption of a flat measure over packing structure for 2D bidisperse packings, 2) we measure the dependence of number of nearest neighbors on global packing fraction, and 3) we observe the evolution of the Granocentric Model with increased dimension.

Une vésicule est une goutte enrobée d'une bicouche lipidique plongée dans un autre fluide. Si un tel objet peut parfois être considéré comme un modèle mécanique en biophysique, il est surtout un système physique aux propriétés remarquables. Ainsi, l'étude d'une vésicule hors équilibre (sous écoulement par exemple) connaît un engouement ces dernières années et ce, à la fois, gràce aux progrès théoriques associés intimement à un développement numérique récent important et les techniques de microfluidique permettant de manipuler de si petits objets de manière contrôlée. Nous nous intéressons expérimentalement et théoriquement/numériquement à la dynamique de vésicules pesantes. Le premier exemple est celui d'une vésicule en adhésion sur un substrat afin d'étudier la dynamique de dé-adhésion (unbinding process) dans un écoulement. Leurs formes et leurs dynamiques sont variées : sphère tronquée, « oeuf », génération de tubes lipidiques, formation de perles... Le deuxième exemple plus simple est celui d'une vésicule pesante dans un milieu infini qui présente aussi une grande diversité de formes stationnaires et instationnaires.

We show that AGT conjecture, relating the partition function in N=2 supersymmetric four-dimensional quiver Gauge Theories, with conformal blocks is valid and gives the simple combinatorial expansion for these blocks.

The hard-disk model has exerted outstanding influence on computational
physics and statistical mechanics. Decades ago, hard disks were the first
system to be studied by Markov-chain Monte Carlo methods and by molecular
dynamics. It was in hard disks, through numerical simulations, that a
two-dimensional melting transition was first seen to occur even though such
systems cannot develop long-range crystalline order. Analysis of the system
was made difficult by the absence of powerful simulation methods.
In recent years, we have developed a number of powerful Monte Carlo
algorithms for hard disks and related systems. I will in particular show how
the powerful event-chain Monte Carlo algorithm which has allowed us to prove
that hard disks melt with a first-order transition from the liquid to the
hexatic and a continuous transition from the hexatic to the solid.

After a brief introduction to the theory of Painlevé equations, I will present in more detail the classification of algebraic solutions to Painlevé VI. The approach will be based on the study of finite orbits of a braid group action on the monodromy of the associated linear system. The resulting list is a nonlinear analog of the Schwarz's table, describing 15 cases when hypergeometric functions can be expressed algebraically.

Des travaux récents ont montré que certains phénomènes, qui ne se produisent qu’à haute pression pour des phases non confinées, peuvent être observés dans des matériaux nanoporeux dans des conditions de température et pression ambiantes. De tels phénomènes induits par des effets de surface ou de confinement incluent l’observation de phases haute pression ou réactions à haute pression. Ainsi, les glaces VII, VIII et IX, qui n’apparaissent qu’à des pressions supérieures à 1 GPa pour un système volumique, ont été observées dans des charbons poreux à température ambiante et sous une pression externe atmosphérique. Dans cet exposé, je présenterai dans un premier temps des travaux de simulation dans lesquels ces effets de haute pression ont pu être mis en évidence. Ainsi,
nous verrons comment la forte dépendance en pression externe de la température de solidification
d’un fluide confiné peut-être expliqué par des variations importantes de la pression mécanique
au sein du pore. Nous verrons également comment des effets dits « poromécaniques » peuvent
expliquer les dommages causés à une pâte de ciment en condition de cycle gel/dégel. Enfin, dans
un deuxième temps, après m’être intéréssé au calcul par simulation moléculaire du tenseur de
pression au sein de la phase confinée, je présenterai un travail où nous avons trouvé, en accord avec l’expérience, que l’adsorption de gaz dans un solide microporeux (CO2 dans une zéolithe silicalite) accroît ses propriétés mécaniques en augmentant son module élastique.

Cells and tissues rearrange under the action of chemical signals. Numerous examples are found in eggshell development, wing disc remodeling, dorsal closure, wound healing, etc. In many cases, this can be attributed to changing local mechanical properties of cytoskeleton due to motor attachment/detachment and rearrangement of the actin network triggered by signaling. Motor activity may either stiffen the network due to stronger prestress or soften it due to motor agitation, in accordance with experimental data. Prestress anisotropy, which may be induced by redistribution of motors triggered by either external force or a chemical signal, causes polarization of cells and anisotropy of elastic moduli. This leads to reshaping of tissues and may cause symmetry-breaking instabilities that induce local inhomogeneities. We model interaction of chemical signaling, polarization, and mechanical deformation both with the help of cellular mechano-diffusive models (applied to reshaping of the Drosophila wing disc and spreading of an epithelial layer in wound healing) and continuous models that facilitate analysis of the various instabilities.

Bayesian statistical methods offer a simple and consistent framework for incorporating uncertainties into a multi-parameter inference problem. In this talk we apply these methods to a selection of current direct dark matter searches. We consider the simplest scenario of spin-independent elastic WIMP scattering, and infer the WIMP mass and cross-section from the experimental data with the essential systematic uncertainties folded into the analysis. In the same vein, we also investigate the impact of astrophysical uncertainties on the preferred WIMP parameters. In addition we investigate the question of whether the recent modulation signal claimed by CoGeNT is best explained by the dark matter (DM) hypothesis from a Bayesian model comparison perspective, finding that the no modulation model is excluded with odds in excess of 455 : 1 when all energy bins are included in the analysis. However the requirement that the modulated signal of being compatible with the total rate lowers significantly the evidence. Therefore we investigate whether anisotropic velocity distributions can help to mitigate the tension between the CoGeNT total and modulated rates, and find encouraging results.