Software is taking an increasingly fundamental role in our society, as a technological tool as well as in social infrastructures. Exploring the pathways of open-source software production, and of more general collective efforts enabled by information-communication technology, is a major challenge for contemporary science. I will show that a quantitative approach to these subjects, based on the intuitions and methods of statistical physics, is fruitful and can provide unexpected insight into other fields as well. I will focus on size (of a piece of software or other product), which is an informative macroscopic quantity. Analysis of data from empirical systems, as well as mathematical modelling, brings out fascinating regularities. From the dynamics of Linux packages - with a digression into mammalian evolution -, to the universal traits of open collaborations such as Wikipedia, quantitative laws akin to those of physics emerge as the backbone of complexity.

The clockwork mechanism has recently been proposed as a natural way to generate hierarchies among parameters in certain models. The mechanism is characterised by a very specific pattern of spontaneous and explicit symmetry breaking, and the presence of new light states. In this talk, I will discuss the clockwork mechanism and its manifestation in the scalar, fermion and gauge boson cases. I will also present a possible generalization of the Abelian clockwork models to non-Abelian clockwork models. Moreover, I will show how the clockwork mechanism can be used to generate flavor symmetries in the Standard Model. I will briefly discuss the continuum clockwork model, which are realised in five-dimensional linear-dilaton geometries.

The SID4Bio is an innovative instrument for quantitative phase imaging in light microscopy.
Based on a patented technology, the SID4Bio offers a contrast enhancement for cells observation with no marker which enables time lapse over long period of time.  The image provides Optical path difference (OPD) that can be statistically analyzed for the study of single-cell or cell populations. It makes possible measuring the single-cell dry mass and density. Single-cell distribution of these innovative parameters enable to quantify morphology. It enables to rigorously segment and follow in time division, apoptosis, and motility. It also applies to drugs effect comparison or parasite counting….

A common theme in statistical physics is that we can better understand systems' behaviour by analysing their fluctuations, and the probabilities of rare events, in which the system behaves in an unusual way. Recently, there has been a focus on dynamical fluctuations, and a particular type of rare event known as large deviations. I will explain what these events are, and give some examples where they reveal interesting behaviour, including phase transitions in one-dimensional systems [1,2], the coupling of structure with dynamics in glasses [3], and applications to shear flow [4].

[1] R. L. Jack, I. R. Thompson and P. Sollich, Phys. Rev. Lett. 114, 060601 (2015).
[2] T. Nemoto, R. L. Jack, and V. Lecomte, Phys. Rev. Lett. 118, 115702 (2017).
[3] D. Coslovich and R. L. Jack, J. Stat. Mech. (2016) 074012.
[4] R. L. Jack and R. M. L. Evans, J. Stat. Mech. (2016) 093305.

In this talk I will discuss low-scale leptogenesis with a particular focus on its testable regimes. In the first part I will discuss leptogenesis with right-handed neutrinos around the electroweak scale, briefly presenting the theoretical description of this mechanism in relation to flavour effects, together with its relevance for testable models at the electroweak scale. In the second part I will focus on leptogenesis below the electroweak scale, and discuss how leptogenesis can proceed, in this case, via the lepton-number violating decays of the Higgs scalar doublet. I will also briefly comment on the testability of this scenario in the near future, for instance at the proposed SHiP experiment at CERN, and the relation with the other mechanism active in the same mass range, i.e. leptogenesis via right-handed neutrino oscillations.

The interactions of non-Brownian particles and liquids contribute to the complexity of many environmental, industrial and biological processes, including the preparation and transport of slurry, and the contamination of surfaces. However, the local fluid-particle interactions that are required to describe situations where interfacial forces come into play cannot be captured by classical rheological approaches. In this talk, I will discuss two examples of recent studies in which we address this complex coupling.

I will first consider the flow of a dry granular material on a wet granular susbtrate. This situation is important in industrial blending and geophysical processes, yet it remains poorly understood because of the interplay between the particles, the fluid and interfacial effects. Our experiments show that the wet granular aggregate grows over time by trapping flowing dry particles. The accretion rate exhibits a complex time dependence that we rationalize by accounting for the local mechanisms of grain capture. In the second part of the talk, I will describe thin-film flows of suspensions when the thickness of the liquid layer is comparable to the particle size, which leads to unexpected dynamics. Indeed, in this situation, the particles deform the liquid interface, which modifies the transport of particles and could result in the contamination of the surface and the loss of transported material but also modify the stability of the liquid film.

Les fibres optiques sont communément utilisées en astronomie pour lier les télescopes aux spectrographes. Cet exposé propose un résumé des points suivants :
- Avantages et inconvénients
- Propriétés des fibres: transmission, dégradation d'ouverture, bruit modal, et mélange photométrique
- Couplage au télescope - fibre et couplage fibre - collimateur
- Découpeur d'image et pouvoir de résolution
Un exemple concret d'un spectrographe échelle fermera l'exposé

Contact angle hysteresis (CAH), where the motion of a contact line between a liquid interface and a solid substrate is pinned by the physical roughness and/or chemical inhomogeneity on the solid surface, is an outstanding problem in interfacial dynamics and has been with us for many years. Despite of numerous efforts, one still has a poor understanding of CAH on many ambient solid surfaces of interest. The study of CAH is of fundamental interest for our general understanding of a common class of problems involving elastic dynamics in random force fields and also has immense practical applications in tertiary oil recovery, drag reduction, advanced materials and microfluidics. In this talk I will present our recent experimental efforts in developing an atomic force microscope (AFM) based hanging fiber probe for the study of contact line dissipation and pinning-depinning dynamics [1-3]. With this new technique, AFM is used as a force sensor to measure the speed-dependent capillary force hysteresis and relaxation of a moving contact line formed on a long vertical glass fiber of a few microns in diameter with one end glued onto a AFM cantilever and the other end in contact with a liquid-air interface. Applications of this technique to the study of contact line dissipation and wetting dynamics will be discussed.

*Work done in collaboration with Dongshi Guan, Yongjian Wang, Elisabeth Charlaix and was supported by the Research Grants Council of Hong Kong SAR.

[1] “Asymmetric and speed-dependent capillary force hysteresis and relaxation of a suddenly stopped moving contact line,” D.-S. Guan, Y.-J. Wang, E. Charlaix and P. Tong, Phys. Rev. Lett. 116, 066102 (2016).

[2] “Understanding of Contact Angle Hysteresis on an Ambient Solid Surface,” Y. J. Wang, S. Guo, H.-Y. Chen, and P. Tong, Phys. Rev. E 93, 052802 (2016).

[3] “Simultaneous observation of asymmetric speed-dependent contact force hysteresis and slow relaxation of a suddenly stopped moving contact line,” D.-S. Guan, Y.-J. Wang, E. Charlaix and P. Tong, Phys. Rev. E 94, 042802 (2016).