Programme

  • 09:30 Ouverture

  • 09:35 - 10:20 Gian Luca Lippi - Two (apparent) Fundamental Paradoxes in Laser Physics +/-

Two (apparent) Fundamental Paradoxes in Laser Physics

Gian Luca Lippi
gian_luca.lippi@inln.cnrs.fr
Institut Non Linéaire de Nice, 1361 route des Lucioles Sophia Antipolis F-06560 Valbonne, FRANCE
Lasers have been around for over five decades and, originally considered “a solution in search for a problem”, have become ubiquitous in everyday’s life and technology. A mathematical description has been elaborated over the years and has lead to very well-established models whose predictive power has been proven time and again. A little-known shortcoming of most models, however, is that they are in open conflict with Quantum Mechanics and Nonlinear Physics. The paradoxes will be discussed and an explanation will be offered for the reasons why such non-trifling inconsistencies are largely ignored, usually without trouble.

  • 10:20 - 10:45 Pause café

  • 10:45 - 11:30 Sid Touati - Analyse et optimisation des programmes de calculs hautes performances +/-

Analyse et optimisation des programmes de calculs hautes performances

Sid Touati
Sid.Touati@inria.fr
INRIA Sophia Antipolis. Projet AOSTE. 2004 route des lucioles. BP 93. 06902 Sophia Antipolis
  1. Notions des performances des programmes et leurs mesures
  2. Différences entre les calculs intensifs et les calculs hautes performances
  3. Les leviers pour améliorer les performances d’un programme
  4. Optimisation des performances de codes par programmation adéquate et compilation avancée
  5. Les processeurs multi-cœurs et leurs implications sur les performances des applications parallèles
  6. Analyses statistiques des performances des applications
  7. Conclusion

  • 11:30 - 12:15 Tristan Guillot - Internal structures and compositions of giant (exo)planets: From CoRot to Juno +/-

Internal structures and compositions of giant (exo)planets: From CoRot to Juno

Tristan Guillot
guillot@obs-nice.fr

Observatoire de la Cote d’Azur CNRS / Laboratoire Cassiopée B.P. 4229 06304 Nice Cedex 4 FRANCE

One can now attempt to determine the abundances of key species in the atmospheres of exoplanets. In parallel, the knowledge of the densities of these exoplanets inform us on their bulk composition in terms of amounts of dense material (rocks and ices) compared to light ones (hydrogen and helium). Linking these constraints seems natural and, intuitively, one would expect dense planets to contain more heavy elements in their atmospheres. However, several physical processes, in particular the formation of a central core and the growth of a deep outer radiative zone, should decouple partially or even completely interior and atmospheric composition. Depending on how heavy elements were delivered to the planets, their atmospheres may have very different compositions. I will discuss how transit surveys like CoRoT and subsequent spectroscopic observations have improved our view of the compositions of giant exoplanets. I will compare these results to what is known about giant planets in our solar system and will discuss how Juno’s arrival in orbit around Jupiter in July 2016 should provide detailed constraints on its internal structure and composition.

  • 12:15 - 13:45 Déjeuner

  • 13:45 - 14:30 Stefano Musacchio - Dimensional transitions in turbulent flows +/-

Dimensional transitions in turbulent flows

Stefano Musacchio
stefano.musacchio@gmail.com

CNRS, UMR 6621 Laboratoire J.A. Dieudonné Université de Nice Sophia-Antipolis Parc Valrose, 06108 Nice Cedex2, France

The dimensionality of the space has remarkable effects on the dynamics of turbulent flows. In three dimensions, the nonlinear interaction between different scales is described by the Kolmorogov-Richardson direct cascade: the kinetic energy injected at large scale by an external forcing is transferred to smaller and smaller eddies until it reaches the scales where it is dissipated by viscosity. By contrast, in two dimensions, the simultaneous conservation of kinetic energy and enstrophy results in an inverse energy cascade; i.e., the energy injected by the forcing is transferred to large-scale structure. In this lecture I will discuss the phenomenology of turbulent flows confined in thin fluid layers, which exhibit a transition from two-dimensional to three-dimensional dynamics as the thickness of the layer is increased. I will show that the transition is characterized by an intermediate regime in which both the direct and inverse cascades coexist. I will discuss the mechanisms which originate this phenomenon, focusing on the role played by inviscid invariants.

  • 14:30 - 15:15 Michel Boër - Les messagers de l’Univers, l’aube d’une nouvelle astrophysique +/-

Les messagers de l’Univers, l’aube d’une nouvelle astrophysique

Michel Boër
Michel.Boer@unice.fr

CNRS ARTEMIS UMR 7250 Observatoire de la Côte d’Azur BP 4229 06304 Nice Cedex 4 France

Jusqu’à maintenant c’est la lumière qui nous fournit l’information sur le cosmos, tout au moins au delà du système solaire. Le photon présente quelques inconvénients, comme ses capacités d’interaction sur son trajet vers la l’observateur, et il ne reflète souvent que très indirectement les processus internes aux objets. L’exemple récent de BICEP montre qu’il est très délicat d’utiliser le photon pour comprendre les processus gravitationnels stochastiques cosmologiques. Nous sommes cependant à l’aube d’une véritable révolution observationnelle en astrophysique. Des neutrinos de très hautes énergies sont détectés par ICECUBE. Prochainement les versions “avancées” de Virgo et LIGO ont de bonnes chances de faire les premières détections d’ondes gravitationnelles. Ceci ne sera pas uniquement une confirmation éclatante d’une des conséquences majeures de la théorie de la relativité générale: cela permettra à l’astrophysicien de recueillir une information sur l’Univers et ses objets qui ne lui est pas accessible maintenant. Il est essentiel que dès avant la détection effective de ces nouveaux messagers, la communauté astrophysique s’empare du sujet tant sur le plan théorique qu’observationnel.

  • 15:15 - 15:45 Pause café

  • 15:45 - 16:30 Wilfried Blanc - Des nanoparticules dans les fibres optiques, un oxymore ? +/-

Des nanoparticules dans les fibres optiques, un oxymore ?

Wilfried Blanc
wilfried.blanc@unice.fr
LPMC, CNRS UMR 7336 Université de Nice Sophia-Antipolis, Parc Valrose 06108 Nice cedex 2 FRANCE
Alors que la fonction première d’une fibre optique est de guider la lumière, pourquoi vouloir introduire des nanoparticules qui vont à l’encontre de la propagation en diffusant la lumière ?