Pairing in a two-component ultracold Fermi gas: Phases with broken-space symmetries

We explore the phase diagram of a two-component ultracold atomic Fermi gas interacting with zero-range forces in the limit of weak coupling. We focus on the dependence of the pairing gap and the free energy on the variations in the number densities of the two species while the total density of the system is held fixed. As the density asymmetry is increased, the system exhibits a transition from a homogenous Bardeen-Cooper-Schrieffer (BCS) phase to phases with spontaneously broken global space symmetries. One such realization is the deformed Fermi surface superfluidity (DFS) which exploits the possibility of deforming the Fermi surfaces of the species into ellipsoidal form at zero total momentum of Cooper pairs. The critical asymmetries at which the transition from DFS to the unpaired state occurs are larger than those for the BCS phase. In this precritical region the DFS phase lowers the pairing energy of the asymmetric BCS state. We compare quantitatively the DFS phase to another realization of superconducting phases with broken translational symmetry: the single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell phase, which is characterized by a nonvanishing center-of-mass momentum of the Cooper pairs. The possibility of the detection of the DFS phase in the time-of-flight experiments is discussed and quantified for the case of 6Li atoms trapped in two different hyperfine states.

La stratégie thérapeutique anti-VEGF améliore le pronostic visuel de la dégénérescence maculaire liée à l'âge exsudative [Intravitreal anti-VEGF injections improve the visual prognosis of wet age related macular degeneration].

Age related macular degeneration (AMD) is an ocular disease with high prevalence among elderly persons. Two different forms exist: dry AMD, usually slowly progressive, and neovascular AMD (wet form) more aggressive. Photodynamic therapy is used to treat the wet form and anti VEGF treatments recently became available and offer a real change in the prognostic of wet AMD. Two products are registered and used in Switzerland (Macugen and Lucentis), a third "off labels product", Avastin is also currently used in clinical practice. Nevertheless, both the duration of treatment and the number of injection requested to stabilise the disease were not defined in the studies. Ongoing studies are mainly evaluating combined treatments and long acting form of the drug.

Symmetries and fixed point stability of stochastic differential equations modeling self-organized criticality

A stochastic nonlinear partial differential equation is constructed for two different models exhibiting self-organized criticality: the Bak-Tang-Wiesenfeld (BTW) sandpile model [Phys. Rev. Lett. 59, 381 (1987); Phys. Rev. A 38, 364 (1988)] and the Zhang model [Phys. Rev. Lett. 63, 470 (1989)]. The dynamic renormalization group (DRG) enables one to compute the critical exponents. However, the nontrivial stable fixed point of the DRG transformation is unreachable for the original parameters of the models. We introduce an alternative regularization of the step function involved in the threshold condition, which breaks the symmetry of the BTW model. Although the symmetry properties of the two models are different, it is shown that they both belong to the same universality class. In this case the DRG procedure leads to a symmetric behavior for both models, restoring the broken symmetry, and makes accessible the nontrivial fixed point. This technique could also be applied to other problems with threshold dynamics.

Remote Synchronization Reveals Network Symmetries and Functional Modules

We study a Kuramoto model in which the oscillators are associated with the nodes of a complex network and the interactions include a phase frustration, thus preventing full synchronization. The system organizes into a regime of remote synchronization where pairs of nodes with the same network symmetry are fully synchronized, despite their distance on the graph. We provide analytical arguments to explain this result, and we show how the frustration parameter affects the distribution of phases. An application to brain networks suggests that anatomical symmetry plays a role in neural synchronization by determining correlated functional modules across distant locations.

[7 phot. d'anthropologie (mannequins représentant des hommes de la préhistoire, des Egyptiens, des Grecs anciens), peut-être de l'exposition liée au Congrès d'anthropologie de Neuchâtel de déc. 1889, don du prince Roland Bonaparte]

Donateur : Bonaparte, Roland (1858-1924)

Dégénérescence maculaire liée à l'âge exsudative: efficacité et limites des différents traitements [Exudative age-related macular degeneration: efficacy and limits of the different treatments].

Ocular neovascularizations are responsible for irreversible loss of vision in various diseases, including age-related macular degeneration. Treatments have changed greatly, and photodynamic therapy with verteporfin has come into common use. However, the visual prognosis remains poor. The recent approval of new antiangiogenic molecules such as ranibizumab and pegaptanib should allow for new therapeutical possibilities. The unapproved ophthalmological use of bevacizumab requires further studies. This paper updates what is known about old and new neovascularization treatments: their mechanism of action, their efficacy, and their toxicity. It reviews the principal clinical studies, and concludes with the recognized recommendations. For the first time, ophthalmologists can hope not only to stabilize loss of vision, but also to improve visual acuity. Complementary treatments can now be tested in associations, concomitantly or not, with the hope of improving visual results.

Différenciation des trajectoires professionnelles liée à la transition à la parentalité en Suisse

Les travaux qui se sont intéressés à l'hypothèse des avantages et désavantages cumulatifs (ADC) dans la perspective du parcours de vie montrent comment, au sein d'une même cohorte, des différences initiales pour une caractéristique déterminée (sexe, statut social, santé) contribuent à structurer des trajectoires de vie différenciées. La plupart de ces études se concentrent sur l'empan de vie sans mesurer l'effet que des transitions particulières jouent dans ce processus. Dans cet article nous nous centrons sur la transition à la parentalité pour montrer que le type d'insertion professionnelle des partenaires avant cette transition explique la différenciation subséquente de leurs trajectoires professionnelles. Abstract Life course studies focusing on the cumulated advantages and disadvantages (CAD) hypothesis indicate that initial differences in a specific characteristic (sex, social status, or health) have an impact on intracohort differentiation. Most of these studies consider an entire life course and do not focus on specific transitions as a key moment for differentiation. In this article, the researchers focus on the transition to parenthood, showing that variations in occupational participation of both partners before the birth of a first child explain how professional trajectories differentiate after the birth of the child. Zusammenfassung Die Arbeiten, die sich für die Hypothese der kumulierten Vor- und Nachteile in einer Lebenslaufperspektive interessiert haben, zeigen, wie anfängliche Unterschiede bezüglich bestimmter Charakteristiken (Geschlecht, sozialer Status, Gesundheit) innerhalb einer Kohorte zur Strukturierung unterschiedlicher Lebensläufe beitragen. Die meisten dieser Studien konzentrieren sich auf den Gesamtlebenslauf, ohne die Effekte spezifischer biographischer Übergänge zu messen. In diesem Artikel beschränken wir uns auf den biographischen Übergang zur Elternschaft. Wir zeigen auf, wie die Erwerbssituation der Partner vor diesem Übergang die nachfolgende Differenzierung ihrer Berufsverläufe beeinflusst.

Dernière partie du roman de Tristan, attribuée à LUCE DU GAST et ÉLIE DE BORON.

Incomplet du commencement et de la fin. — Miniatures.

Élie de Saint Gilles : chanson de geste / publ. avec introd. par Gaston Raynaud ; trad. par Eugène Koelbing

[Élie de Saint-Gilles (français ancien). 1879]

Élie de Saint Gilles : chanson de geste / publ. avec introd. par Gaston Raynaud ; trad. par Eugène Koelbing

[Élie de Saint-Gilles (français ancien). 1879]