Murs dans les nano-fils ferromagnétiques pincés
Gilles Carbou, (Université de Pau, LMA)
Les fils ferromagnétiques sont utilisés pour le stockage des données numériques. Les informations sont codées sous forme de domaines ferromagnétiques séparés par des murs. La fiabilité du stockage dépend de manière cruciale de la stabilité de la position des murs, celle ci étant assurée dans les applications par des encoches faites dans le fil. Après avoir établi un modèle 1d de tels fils avec plusieurs pincements, on étudiera l’existence et la stabilité de solutions codant une suite de bits quelconque. Il s’agit d’un travail en collaboration avec David Sanchez.
Séminaire d’interêt général TBA
Martin Lopez Corredoira (Instituto de Astrofisica de Canarias)
Séminaire commun avec le CPPM et l’UFR Sciences (Attention date et lieu inhabituels).
“The Twilight of the Scientific Age”
This talk gives a challenging point of view about science and its history/philosophy/sociology. Science is in decline. After centuries of great achievements, the exhaustion of new forms and fatigue have reached our culture in all of its manifestations including the pure sciences. Our society is saturated with knowledge which does not offer people any sense in their lives. There is a loss of ideals in the search for great truths and a shift towards an anodyne specialized industry. A wide audience of educated people interested in these topics will most likely respond to the ideas expressed here, as things they have thought about or observed but have not dared to say out loud.
Voir aussi l’annonce sur le site de l’UFR Sciences (il y aura également un séminaire identique mercredi 5 avril à 17:00, amphi de sciences naturelles, campus de St Charles)
Hawking radiation in Bose-Einstein condensates
In 1981 Bill Unruh predicted that the analog of the Hawking effect
(quantum particle creation from black holes) is present in condensed matter systems. I will focus on a proposal to detect it in Bose-Einstein condensates through correlation measurements, and on recent experimental results.
Identifying defects in a locally perturbed infinite periodic layers
Houssem Haddar, (Ecole Polytechnique, CMAP)
As part of our efforts to design imaging algorithms for unknown complex backgrounds, we propose and analyze a new sampling method to recover the support of a local perturbation in a periodic layer from measurements of scattered waves at a fixed frequency. Our method is capable of directly reconstructing the geometry of the perturbation, without the need for knowing or reconstructing the background periodic media. The related analysis is based on studying sampling methods using a single Floquet-Bloch mode. This analysis introduces a new type of interior transmission problems that couple usual interior transmission problems for one mode with scattering problems for the other modes. We shall discuss and analyze this problem as well as the sampling method for differential imaging and present some related numerical results. This is a joint work with Thi-Phong Nguyen.
Slow Manifold Reduction of the Two-Fluid Maxwell System
Joshua Burby (Courant Institute, New York)
The two-fluid Maxwell system couples frictionless electron and ion
fluids via Maxwell’s equations. When the frequencies of light waves,
Langmuir waves, and single-particle cyclotron motion are scaled to be
asymptotically large, the two-fluid Maxwell system becomes a fast-slow
dynamical system. The slow manifold for this fast-slow system is an
invariant set in the two-fluid Maxwell phase space on which solutions
are free of high-frequency oscillations. In this talk, I will present
expressions for the (asymptoticallly-scaled) two-fluid Maxwell system
restricted to its slow manifold. In the leading order approximation, the
slow dynamics are given by magnetohydrodynamics (MHD). Higher order
approximations of the slow dynamics give an infinite hierarchy of
conservative extensions to MHD, which include Hall MHD and inertial MHD.
The slow dynamics obey a variational principle and possess a
noncanonical Hamiltonian structure. By employing infinite-dimensional
Lie transforms, the Poisson structure may be obtained in closed form.
Progress on Old and New Themes in cosmology (PONT) 2017
The conference will address the cardinal issues of the dark universe today, gathering a selected number of scientists working in cosmology and particle physics in the inspiring and monumental setting of Avignon. There will be a limited number of review talks by leading experts in each field and selected contributed talks, fostering thorough debates. Some time will be allocated to discussion sessions.
Dates : April 24-28, 2017
Organizers : Philippe Brax (CEA IPhT Saclay), Chiara Caprini (CNRS APC Paris), Marco Cirelli (CNRS LPTHE Jussieu Paris), Christian Marinoni (CPT Marseille), Géraldine Servant (DESY Hamburg), Nicola Tamanini (CEA IPhT Saclay)
Rencontre de Physique des Particules
The Rencontre de Physique des Particules (RPP) is an annual meeting of theoretical physicists working in France in the field of elementary particles and high energy physics. In 2017 the meeting will be organised by the Centre de Physique Théorique, Marseille. Various topics will be covered, on each of which there will be an invited review talk as listed below :
Standard Model : Alberto Ramos (CERN)
Flavour physics : Diego Guadagnoli (LAPTh)
Beyond the SM : Felix Brümmer (LUPM)
Astroparticle physics : Andreas Goudelis (LPTHE)
Cosmology : Federico Piazza (CPT)
Formal aspects : Emeri Sokatchev (LAPTh)
Experimental Update : Laurent Vacavant (CPPM)
Each review talk will be followed by additional presentations on the topic, and participants are encouraged to submit abstracts in order to contribute.
Dates : April 24-26, 2017
Scientific committee : Aoife Bharucha, Jérôme Charles, Laurent Lellouch and Marc Knecht of the CPT in collaboration with members of the CPPM (Lorenzo Feligioni, Giampiero Mancinelli, Laurent Vacavant) and the L2C, Montpellier (Gilbert Moultaka).
For more details see the conference website