Semi-classical approach for Anosov diffeomorphisms and Ruelle resonances

In this paper, we show that some spectral properties of Anosov diffeomorphisms can be obtained by semi-classical analysis. In particular the Ruelle resonances which are eigenvalues of the Ruelle transfer operator acting in suitable anisotropic Sobolev spaces and which govern the decay of dynamical correlations, can be treated as the quantum resonances of open quantum systems in the Aguilar-Baslev-Combes theory or the more recent Helffer-Sjostrand phase-space theory.Comment: 48 page

A simulation-based approach to assess impacts of urban logistics policies on traffic flow dynamics

International audienceIn urban environments, there are now many challenging problems concerning freight transport.As cities around the world grow rapidly, there is an increase in pickup-delivery truck traffic inurban areas. It turns out that commercial traffic is now a major source of externalities in metroareas, including congestion, noise, air pollution (small particulates, NOx, greenhouse gasemissions), and traffic incidents [1].To overcome these issues, many interesting and innovative strategies have been developed inEurope and other parts of the world. Especially, some researchers proposed the idea of citylogistics to solve these difficult problems [2-3]. The idea of this concept is to rationalize thefreight activities in cities by optimizing operations considering the traffic conditions and thecongestion issues. Consequently, public authorities strongly need decision support frameworksto evaluate urban logistics planning and management.It turns out that a key point in predicting the impacts of city logistics is the influence of freighton traffic flow dynamics. Particularly, pickup-delivery trucks maneuvers generate roadcapacity reduction and lead to delay for individual drivers. Although this is a crucial topic, theliterature rarely addresses this issue. This paper aims to fill this lack of understanding byincorporating the effects of urban freight in a traffic flow model

Genetic hitchhiking in a subdivided population of Mytilus edulis

<p>Abstract</p> <p>Background</p> <p>Few models of genetic hitchhiking in subdivided populations have been developed and the rarity of empirical examples is even more striking. We here provide evidences of genetic hitchhiking in a subdivided population of the marine mussel <it>Mytilus edulis</it>. In the Bay of Biscay (France), a patch of <it>M. edulis </it>populations happens to be separated from its North Sea conspecifics by a wide region occupied only by the sister species <it>M. galloprovincialis</it>. Although genetic differentiation between the two <it>M. edulis </it>regions is largely non-significant at ten marker loci (average F_ST~0.007), a strong genetic differentiation is observed at a single locus (F_ST= 0.25). We validated the outlier status of this locus, and analysed DNA sequence polymorphism in order to identify the nature of the selection responsible for the unusual differentiation.</p> <p>Results</p> <p>We first showed that introgression of <it>M. galloprovincialis </it>alleles was very weak in both populations and did not significantly affect their differentiation. Secondly, we observed the genetic signature of a selective sweep within both <it>M. edulis </it>populations in the form of a star-shaped clade of alleles. This clade was nearly fixed in the North Sea and was segregating at a moderate frequency in the Bay of Biscay, explaining their genetic differentiation. Incomplete fixation reveals that selection was not direct on the locus but that the studied sequence recombined with a positively selected allele at a linked locus while it was on its way to fixation. Finally, using a deterministic model we showed that the wave of advance of a favourable allele at a linked locus, when crossing a strong enough barrier to gene flow, generates a step in neutral allele frequencies comparable to the step observed between the two <it>M. edulis </it>populations at the outlier locus. In our case, the position of the barrier is now materialised by a large patch of heterospecific <it>M. galloprovincialis </it>populations.</p> <p>Conclusion</p> <p>High F_SToutlier loci are usually interpreted as being the consequence of ongoing divergent local adaptation. Combining models and data we show that among-population differentiation can also dramatically increase following a selective sweep in a structured population. Our study illustrates how a striking geographical pattern of neutral diversity can emerge from past indirect hitchhiking selection in a structured population.</p> <p>Note</p> <p>Nucleotide sequences reported in this paper are available in the GenBank™ database under the accession numbers <ext-link ext-link-type="gen" ext-link-id="EU684165">EU684165</ext-link> – <ext-link ext-link-type="gen" ext-link-id="EU684228">EU684228</ext-link>.</p

Survival of eclogite xenolith in a Cretaceous granite intruding the Central Dabieshan migmatite gneiss dome (Eastern China) and its tectonic implications.

International audienceInvestigation of an eclogite xenolith, discovered in a Cretaceous granite from the Central Domain of the Dabieshan massif in eastern China, yields new petrological insights into the high to ultrahigh-pressure metamorphism, experienced by the Qinling-Dabie orogen. Prior to inclusion as a xenolith in the granite during the Early Cretaceous, this eclogite xenolith had recorded a complex metamorphic evolution that complies with subduction and exhumation processes experienced by the continental crust of the South China Block. Well-preserved mineral parageneses substantiate the prograde and retrograde stages revealed by inclusions in porphyroblastic garnet and zoned minerals such as garnet, comphacite and amphibole in the matrix. The relatively low P/T re-equilibration during a latemetamorphic stage was textually inferred by the presence of aluminous and calcic-subcalcic amphiboles such as katophorite, edenite, taramite and pargasite as main matrix phases. According to our U/Pb, Rb/Sr and new 40Ar/39Ar geochronological results, namely 109 ± 1 and 112 ± 2 Ma plateau ages for muscovite and amphiboles, respectively, two successive but distinct cooling stages account for the thermal history of the granite–migmatite gneiss dome that forms the Central Dabieshan Domain. We argue that prior to the Cretaceous doming, the Central Dabieshan Domain experienced a tectono-metamorphic evolution similar to that observed in the high-pressure to ultra high-pressure units developed in the Southern Dabieshan Domain and Hong'an massif

Scalable machine learning-assisted clear-box characterization for optimally controlled photonic circuits

Photonic integrated circuits offer a compact and stable platform for generating, manipulating, and detecting light. They are instrumental for classical and quantum applications. Imperfections stemming from fabrication constraints, tolerances and operation wavelength impose limitations on the accuracy and thus utility of current photonic integrated devices. Mitigating these imperfections typically necessitates a model of the underlying physical structure and the estimation of parameters that are challenging to access. Direct solutions are currently lacking for mesh configurations extending beyond trivial cases. We introduce a scalable and innovative method to characterize photonic chips through an iterative machine learning-assisted procedure. Our method is based on a clear-box approach that harnesses a fully modeled virtual replica of the photonic chip to characterize. The process is sample-efficient and can be carried out with a continuous-wave laser and powermeters. The model estimates individual passive phases, crosstalk, beamsplitter reflectivity values and relative input/output losses. Building upon the accurate characterization results, we mitigate imperfections to enable enhanced control over the device. We validate our characterization and imperfection mitigation methods on a 12-mode Clements-interferometer equipped with 126 phase shifters, achieving beyond state-of-the-art chip control with an average 99.77 % amplitude fidelity on 100 implemented Haar-random unitary matrices

Middle Carboniferous crustal melting in the Variscan Belt: New insights from U-Th-Pbtot. monazite and U-Pb zircon ages of the Montagne Noire Axial Zone (southern French Massif Central)

International audienceIn France, the Devonian-Carboniferous Variscan orogeny developed at the expense of continental crust belonging to the northern margin of Gondwana. A Visean-Serpukhovian crustal melting has been recently documented in several massifs. However, in the Montagne Noire of the Variscan French Massif Central, which is the largest area involved in this partial melting episode, the age of migmatization was not clearly settled. Eleven U-Th-Pbtot. ages on monazite and three U-Pb ages on associated zircon are reported from migmatites (La Salvetat, Ourtigas), anatectic granitoids (Laouzas, Montalet) and post-migmatitic granites (Anglès, Vialais, Soulié) from the Montagne Noire Axial Zone are presented here for the first time. Migmatization and emplacement of anatectic granitoids took place around 333-326Ma (Visean) and late granitoids emplaced around 325-318Ma (Serpukhovian). Inherited zircons and monazite date the orthogneiss source rock of the Late Visean melts between 560Ma and 480Ma. In migmatites and anatectic granites, inherited crystals dominate the zircon populations. The migmatitization is the middle crust expression of a pervasive Visean crustal melting event also represented by the "Tufs anthracifères" volcanism in the northern Massif Central. This crustal melting is widespread in the French Variscan belt, though it is restricted to the upper plate of the collision belt. A mantle input appears as a likely mechanism to release the heat necessary to trigger the melting of the Variscan middle crust at a continental scale

The contrasted evolutionary fates of deep-sea chemosynthetic mussels (Bivalvia, Bathymodiolinae)

International audienceBathymodiolinae are giant mussels that were discovered at hydrothermal vents and harboring chemosynthetic symbionts. Due to their close phylogenetic relationship with seep species and tiny mussels from organic substrates, it was hypothesized that they gradually evolved from shallow to deeper environments, and specialized in decaying organic remains, then in seeps, and finally colonized deep-sea vents. Here, we present a multigene phylogeny that reveals that most of the genera are polyphyletic and/or paraphyletic. The robustness of the phylogeny allows us to revise the genus-level classification. Organic remains are robustly supported as the ancestral habitat for Bathymodiolinae. However, rather than a single step toward colonization of vents and seeps, recurrent habitat shifts from organic substrates to vents and seeps occurred during evolution, and never the reverse. This new phylogenetic framework challenges the gradualist scenarios from shallow to deep. Mussels from organic remains tolerate a large range of ecological conditions and display a spectacular species diversity contrary to vent mussels, although such habitats are yet underexplored compared to vents and seeps. Overall, our data suggest that for deep-sea mussels, the high specialization to vent habitats provides ecological success in this harsh habitat but also brings the lineage to a kind of evolutionary dead end

Construction and Validation of a Hybrid Lumbar Spine Model For the Fast Evaluation of Intradiscal Pressure and Mobility

International audienceA novel hybrid model of the lumbar spine, allowing fast static and dynamic simulations of the disc pressure and the spine mobility, is introduced in this work. Our contribution is to combine rigid bodies, deformable finite elements, articular constraints, and springs into a unique model of the spine. Each vertebra is represented by a rigid body controlling a surface mesh to model contacts on the facet joints and the spinous process. The discs are modeled using a heterogeneous tetrahedral finite element model. The facet joints are represented as elastic joints with six degrees of freedom, while the ligaments are modeled using non-linear one-dimensional elastic elements. The challenge we tackle is to make these different models efficiently interact while respecting the principles of Anatomy and Mechanics. The mobility, the intradiscal pressure, the facet joint force and the instantaneous center of rotation of the lumbar spine are validated against the experimental and theoretical results of the literature on flexion, extension, lateral bending as well as axial rotation. Our hybrid model greatly simplifies the modeling task and dramatically accelerates the simulation of pressure within the discs, as well as the evaluation of the range of motion and the instantaneous centers of rotation, without penalizing precision. These results suggest that for some types of biomechanical simulations, simplified models allow far easier modeling and faster simulations compared to usual full-FEM approaches without any loss of accuracy