Left-right symmetric model (LRSM) is a well-motivated beyond Standard Model theory, which connects the origin of parity violation to the neutrino mass. We study the viability of having dark matter candidate in the minimal such theory. We find the lightest right-handed (RH) neutrino as keV warm dark matter could be consistent with a TeV-scale window of LR symmetry. In this scenario, the early universe has to experience thermal (over) production of DM and late entropy production/dilution. We discuss the cosmological and low energy experiment constraints, as well as the discovery prospect for the theory at LHC.

Shape is one of the important characteristics for the structures observed in living organisms. Whereas biologists have proposed models where the shape is controlled on a molecular level, physicists, following Turing and d'Arcy Thomson, have developed theories where patterns arise spontaneously. Here, we propose that volume constraints restrict the possible shapes of leaves. Focusing on palmate leaves (with lobes), the central observation is that developing leaves first grow folded inside a bud, limited by the previous and subsequent leaves. We show that the lobe perimeters end at the border of this small volume. This induces a direct relationship between the way it was folded and the final unfolded shape of the leaf. These dependencies can be approximated as simple geometrical relationships that we confirm on both folded embryonic and unfolded mature leaves. We find that independently of their position in the phylogenetic tree, these relationships work for folded species, but do not work for non-folded species. We also realized observations and experiments to understand how leaves folds appear during the development and to understand the role of mechanical constrain inside the bud on the development of leaf shape.

We study the patterning of cholesteric liquid crystal (CLC) alignment and the generation of defects via interfacial contact with Langmuir-Blodgett films exhibiting broken symmetries and interfacial topological defects. The films are previously self-assembled at the air/water interface where they organize into isolated sub-millimeter circular islands featuring polar nematic order with the elongated molecules anchored at a fixed angle of the interface normal (~ 45º), and a tilt orientation tangential to the circular boundary[1]. In contact with the LB-coated glass substrate, LC molecules follow the local in-plane orientation of the amphiphilic molecules in the monolayer. Previous work with nematic liquid crystals revealed the formation of either single twist-escaped or double singular arch-shaped defect loops, which were confined to the vicinity of the LB-coated plate, and were independent on the far-field boundary conditions [2]. When filling the cell with a CLC, the local twist imposed by the hybrid boundary conditions couples to the intrinsic cholesteric pitch, resulting in the formation of edge dislocations pinned between screw dislocations and kinks. Different three-dimensional imaging techniques (Fluorescence Confocal Polarizing Microscopy, and 2- and 3-photon fluorescent imaging) are employed to reveal the configuration of the director field. [1] J. Ignés-Mullol, J. Claret, R. Albalat, J. Crusats, R. Reigada, M. T. M. Romero and F. Sagués, Texture changes inside Smectic-C droplets in azobenzene Langmuir monolayers, Langmuir, 21, 2948 (2005). [2] N. Petit-Garrido, R. P. Trivedi, J. Ignés-Mullol, J. Claret, C. Lapointe, F. Sagués and I. I. Smalyukh, Healing of Defects at the Interface of Nematic Liquid Crystals and Structured Langmuir-Blodgett Monolayers, Phys. Rev. Lett., 107, 177801 (2011)

Many non-equilibrium features of biological systems are associated to the presence of active elements, which operate using an input of chemical energy. This is the case for instance with molecular motors, which are enzymes capable to convert the chemical energy obtained from ATP hydrolysis into mechanical work. Due to their small size, these enzymes operate typically far from equilibrium and undergo large fluctuations. As a result, in these systems, thermodynamic quantities like work or heat are only defined in a statistical sense, and their study requires stochastic thermodynamics. Biofilaments like microtubules and actin filaments, display unusual non-equilibrium dynamical behaviors, and are also capable to convert chemical energy into mechanical work. Finally, we conclude with some general ideas concerning the application of stochastic thermodynamics to driven or slowly evolving non-equilibrium systems.

Structure formation of nanoparticles at interfaces is governed by their effective interactions. I discuss electrostatic and capillary interactions, which become long-ranged at interfaces (in contrast to bulk suspensions) and are the source of novel phenomena. Interactions of charged particles point to a high sensitivity to specific properties of solvated ions and thus these interactions may serve as "probes" for the elecetrostatic double layer. Suitable extensions of the well-known Poisson-Boltzmann equation are discussed which may capture these interactions. - The second part deals with classical density functional calculations for colloidal crystal-liquid interfaces and a discussion of suitable crystallinity order parameters. Results for hard spheres are presented and compared to very recent simulation results for the orientation dependent surface tension.

Dans la cellule, la vie met en jeu une grande diversité de structures, mécanismes et
interactions moléculaires. Je présenterai deux cas d'études différents.
La protéine FepA, présente dans la membrane cellulaire, participe à l'ingestion du fer par
certaines bactéries. FepA contient un réseau d'eau divisé, ramifié et mobile. Nous verrons
comment analyser la topologie complexe et fluctuante de cette protéine, et comment cette
topologie évolue pour préparer le transport du fer.
Dans la cellule, l'ADN interagit constamment avec des protéines qui en assurent l'organisation,
l'intégrité, la lecture, etc. La séquence chimique des bases A,C,G,T le long de la chaîne ADN
n'explique pas toutes les affinités observées. La mécanique et la dynamique du squelette, en
particulier des groupes phosphates, aussi dépendants de la séquence, jouent un rôle important
dans les interactions ADN-protéines. Nous verrons comment cette dynamique module une affinité
spécifique, celle de la protéine E2 du Papillomavirus, et comment elle intervient dans une
interaction non-spécifique, la constitution du nucléosome.

Tree Level Gauge Mediation (TGM) represents a simple and easily testable scenario of gauge mediation at present and future colliders. In this talk I will analyze the structure of TGM and its peculiar predictions, both in the minimal SO(10) realization and the extended E_6 one, focusing then on the possibilities offered by the LHC to discriminate it from other frameworks.

Nous pouvons tous dire quand le film d'un événement familier comme une casserole amenée à ébullition ou un verre se brisant est projeté à l'envers. De même, nous sentons tous que nous pouvons nous souvenir du passé et influencer le futur, et non le contraire. Il y a donc clairement une "flèche" du temps dans l'interprétation de notre expérience quotidienne. Pourtant, les lois fondamentales microscopiques de la physique, classique comme quantique, sont invariantes par renversement du temps. Quelle est donc l'origine de la "flèche" du temps ?