My group is storically involved into two main lines of research: the characterization of cancer stem cells as driving force of cancer and the neurodegenerative patologies due to protein aggregation. In the past, working on the critical pathways involved in metastasis, we demonstrated that the aquaporin, a water channel, is necessary to
organize a psedovascular network in vitro due to its capability to organize F-actin.
We continued on this research, by studying the role of aquaporins for possible volume fluctuations during blebbing in zebrafish primordial germ cells. For the first time we have demontrated that cells do not deform as baloons full of water but they can change their volume due to aquaporins.

More information on my website: oncolab.unimi.it
Center for Complexity and Biosystems: www.complexity.unimi.it

Understanding how materials respond to external mechanical perturbation is a central problem of science and engineering. While for most practical purposes it is useful to idealize the mechanical response of a material as a deterministic function of the externally applied perturbation, disorder and fluctuations are unavoidable, leading to sample-to-sample variations and non-trivial size effects. The size dependence of strength is a well known but still unresolved issue in the fracture of materials and structures. The difficulty in addressing this problem stems from the complex interplay between microstructual heterogeneity and long-range elastic interactions. Furthermore, in micro and nanoscale samples, the plastic yield strength displays size effects and strain bursts, features that are not present in macroscopic samples where plasticity is a smooth process. Large fluctuations both in fracture processes and in microscale plasticity make the use of conventional continuum mechanics problematic and calls instead for a statistically based approach. In this talk, I will review recent results obtained from idelized models of disordered fracture and from more realistic simulations of defected graphene. Finally, I will discuss the size dependence of strain burst statistics as revealed by statistical models for crystal and amorphous plasticity.

"Thé au cube" est la pause café scientifique de l'axe PTh. L'orateur y expose de manière interactive et accessible aux théoriciens non-spécialistes, ses intérêts scientifiques du moment. N'oubliez pas de ramener vos tasses et autres mugs préférés.

Noise and its correlations represent an essential probe of the nature of complex quantum systems. Fluctuations in quantum systems are both of thermal and quantum origin, and telling apart the thermal and quantum components of fluctuations is a formidable challenge. Nonetheless, accomplishing this task would give access to two fundamental aspects: the actual temperature of the quantum degrees of freedom, and their entanglement properties.

Experimental access to noise in condensed-matter setups is often hindered by the large amount of statistics required, and/or by the necessity of developing multi-port measurements. In this respect cold atoms trapped in light-induced potentials offer a unique opportunity to study noise in quantum many-body systems, including the full noise statistics, either in momentum space (via time-of-flight images) or in real space (via in-situ images). In this talk I will first discuss how noise in momentum space can serve as an invaluable tool for thermometry via fluctuation-dissipation relations, generally valid for classical systems; the violation of such relations for quantum systems provides new insight into the structure of quantum fluctuations in momentum space. On the other hand, noise in real space -- in the form of local density fluctuations -- is a direct manifestation of entanglement between a part of an extended quantum system and its complement. Focusing on simple systems of relevance to cold-atom setups, I shall discuss the fundamental links — as well as the discrepancies — between entanglement entropies and density fluctuations, based on a microscopic insight into the spatial structure of both properties.

Soutenance HDR

Single polymers can often display complex and anomalous dynamics. In this talk I will review some examples of single polymers dynamics recently studied by our group: the DNA hairpin folding [1] and the winding/unwinding of a polymer on/from a rod [2-4]. The results of Langevin dynamics simulations indicate that the dynamics is characterized by "anomalous" power-law dependence of various quantities as a function of time. We show how the numerical results can
be explained by force balance arguments using the blob model and a multiphase picture of the polymer conformations.

Abstract: Surface waves play a key role in the quest for harnessing
electromagnetic phenomena at a deep subwavelength scale. This is
especially true in optics due to the possibility of exciting a variety
of plasmon modes and resonances at the surface of nanoscale metallic
samples. For example, miniature plasmonic antennas can be used to tailor
the emission of fluorescent species, as will be discussed in the first
part of this talk with new results on this topic. However, there are
other types of electromagnetic surface waves with properties at least as
interesting as those of plasmons. I will illustrate this point by
showing that surface waves supported by ferrites at microwave
frequencies can be leveraged to synthesize artificial media (or
metamaterials) with strong nonreciprocal responses.

"Thé au cube" est la pause café scientifique de l'axe PTh. L'orateur y expose de manière interactive et accessible aux théoriciens non-spécialistes, ses intérêts scientifiques du moment. N'oubliez pas de ramener vos tasses et autres mugs préférés.

Viscoelastic fluids exhibit an intermediate behavior between elastic solids and dissipative liquids, depending on the time scale at which they are perturbed. Elastic instabilities may occur in the flow of viscoelastic fluids and a general criterion for the onset of these instabilities can be established based on the curvature of flow streamlines and fluid elasticity.
I will present in this talk an overview of the experimental work that I have performed on the characterization of the onset of elastic flow instabilities in viscoelastic (polymeric or wormlike micellar) solutions in different flow geometries (ranging from microfluidic to macroscopic devices), and for different flow protocols.
By performing oscillatory shear experiments in a cone-plate configuration we showed that, for large enough amplitudes of the driving, the homogeneous flow became unstable and it reorganized into different stable shear bands. Similarly, in oscillatory pipe flow the laminar flow became unstable leading to the formation of viscoelastic vortex rings. In steady flows, experiments performed in microfluidic serpentine channels allowed us to determine the influence of shear-thinning on the onset of purely elastic instabilities. Furthermore, we characterized an elastically-driven turbulent flow regime, which displayed anomalous scaling properties.