Hyperbolic structure for a simplified model of dynamical perfect plasticity

This paper is devoted to confront two different approaches to the problem of dynam-ical perfect plasticity. Interpreting this model as a constrained boundary value Friedrichs' system enables one to derive admissible hyperbolic boundary conditions. Using variational methods, we show the well-posedness of this problem in a suitable weak measure theoretic setting. Thanks to the property of finite speed propagation, we establish a new regularity result for the solution in short time. Finally, we prove that this variational solution is actually a solution of the hyperbolic formulation in a suitable dissipative/entropic sense, and that a partial converse statement holds under an additional time regularity assumption for the dissipative solutions

Image Segmentation with Multidimensional Refinement Indicators

We transpose an optimal control technique to the image segmentation problem. The idea is to consider image segmentation as a parameter estimation problem. The parameter to estimate is the color of the pixels of the image. We use the adaptive parameterization technique which builds iteratively an optimal representation of the parameter into uniform regions that form a partition of the domain, hence corresponding to a segmentation of the image. We minimize an error function during the iterations, and the partition of the image into regions is optimally driven by the gradient of this error. The resulting segmentation algorithm inherits desirable properties from its optimal control origin: soundness, robustness, and flexibility

Quelques anecdotes dérisoires tirées de l’historiographie maghrébo-andalouse du moyen-âge

On ne peut pas dire que les ouvrages historiographiques médiévaux rédigés en arabe brillent par leur fantaisie, du moins si l'on en juge d'après ceux qui nous sont parvenus. Ce n'est d' ailleurs pas leur objet. Cette fantaisie qui devrait nous laisser entrevoir un peu de la vie des vivants d' alors, qui leur conserverait un peu de chair et de couleurs, on la trouvera plus facilement dans les textes pro- prement littéraires, "séances" (maqâmât), recueils d' anecdotes, contes, poésies. Certes, des récits merveilleux ( 'aga 'ib wa-àarâ' ib) agrémentent parfois les chroniques. Est-ce par souci de légèreté, de respiration dans un texte au demeu- rant très monotone, jusque dans ses prétentions littéraires - je pense ici aux exer- cices de virtuosité stylistique, comme l'emploi de la prose scandée (saà'), ou au jeu des références en tout genre, coraniques, poétiques, proverbiales, etc. ? Il est permis d'en douter. Car ces récits, même s'ils paraissent échapper à la trame du discours, obéissent néanmoins à son projet global, qui est de rendre compte d'un savoir entendu comme une somme d'informations (gumla min al-a&bâr), l'am- pleur de la collection rassemblée tenant lieu, bien souvent, de véritable connais- sance. Ne rien omettre semble donc être la devise de l'auteur, y compris lorsqu'il nous prévient qu'il en sait encore davantage, et c'est pourquoi il lui arrive de glisser dans l'assortiment qu'il nous tend une pièce suspecte que nous saurons, alertés par quelque formule convenue du type "je ne garantis rien" (wa-llâhu juger à sa juste valeur

Apprentissage implicite des structures linguistiques et musicales (approche multi-méthodologique)

Les objectifs de cette thèse sont multiples. Le premier objectif est de comparer, aux niveaux comportemental et électrophysiologique, l'apprentissage implicite de structures linguistiques et musicales après l'écoute d'un langage artificiel chanté. Alors qu'au niveau comportemental, seule la structure linguistique semble être apprise, les résultats électrophysiologiques révèlent un effet N400 pour les deux dimensions, linguistique et musicale. Le deuxième objectif de cette thèse est d'évaluer comment cet apprentissage est influencé par l'expertise musicale. Nous avons comparé un groupe d'adultes musiciens à un groupe de non musiciens. Alors qu'au niveau comportemental les musiciens sont à peine meilleurs que les non musiciens dans les deux dimensions, les données électrophysiologiques révèlent, via des différences précoces (N1/P2) et tardives (N400), une meilleure segmentation chez les musiciens. De plus, les analyses en potentiels évoqués et en temps-fréquences des données électrophysiologiques enregistrées pendant les phases d'apprentissage révèlent que les musiciens apprennent plus rapidement que les non musiciens. Cependant, un lien de causalité quant aux effets de l'apprentissage de la musique ne peut être mis en évidence qu'en réalisant une étude longitudinale. Nous avons mené une telle étude chez des enfants de 8 ans à qui l'on a fait suivre un apprentissage de la musique ou de la peinture pendant 2 années. Les résultats comportementaux et électrophysiologiques révèlent un large bénéfice de l'apprentissage musical comparé à celui de la peinture démontrant l'importance de la musique dans l'éducation des enfants.The aims of the present thesis were two-folded. Firstly, we wanted to compare behavioral and electrophysiological measures related to the implicit learning of linguistic and musical structures contained within an artificial sung language. While behavioral measures suggest that only the linguistic structure was learned, electrophysiological data revealed similar N400 effects in both linguistic and musical dimensions, suggesting that participants did also learn the musical structure. The second goal was to evaluate to what extent musical expertise can affect speech segmentation. At this aim, we compared a group of adult musicians to a group of nonmusicians. While behavioral data showed that musicians had marginally better performance than non musicians in both dimensions, electrophysiological data revealed, via early (N1/P2) and late (N400) differences, a better speech segmentation in musicians than in non musicians. Moreover, event-related potentials and time-frequency analyzes during learning revealed a faster and more efficient learning process in musicians. However, the only way to unambiguously claim causality between expertise and the observed effects requires a longitudinal approach. At this aim, we conducted a study with 8 year-old children who followed either music or painting lessons over a period of 2 years. Behavioral and electrophysiological data revealed a larger benefit of musical compared to painting training, bringing evidences for the importance of music in childrens' education.AIX-MARSEILLE2-Bib.electronique (130559901) / SudocSudocFranceF

Music Training Positively Influences the Preattentive Perception of Voice Onset Time in Children with Dyslexia: A Longitudinal Study

Previous results showed a positive influence of music training on linguistic abilities at both attentive and preattentive levels. Here, we investigate whether six months of active music training is more efficient than painting training to improve the preattentive processing of phonological parameters based on durations that are often impaired in children with developmental dyslexia (DD). Results were also compared to a control group of Typically Developing (TD) children matched on reading age. We used a Test-Training-Retest procedure and analysed the Mismatch Negativity (MMN) and the N1 and N250 components of the Event-Related Potentials to syllables that differed in Voice Onset Time (VOT), vowel duration, and vowel frequency. Results were clear-cut in showing a normalization of the preattentive processing of VOT in children with DD after music training but not after painting training. They also revealed increased N250 amplitude to duration deviant stimuli in children with DD after music but not painting training, and no training effect on the preattentive processing of frequency. These findings are discussed in view of recent theories of dyslexia pointing to deficits in processing the temporal structure of speech. They clearly encourage the use of active music training for the rehabilitation of children with language impairments

Investigating the impact of captivity and domestication on limb bone cortical morphology: an experimental approach using a wild boar model

The lack of bone morphological markers associated with the human control of wild animals has prevented the documentation of incipient animal domestication in archaeology. Here, we assess whether direct environmental changes (i.e. mobility reduction) could immediately affect ontogenetic changes in long bone structure, providing a skeletal marker of early domestication. We relied on a wild boar experimental model, analysing 24 wild-born specimens raised in captivity from 6 months to 2 years old. The shaft cortical thickness of their humerus was measured using a 3D morphometric mapping approach and compared with 23 free-ranging wild boars and 22 pigs from different breeds, taking into account sex, mass and muscle force differences. In wild boars we found that captivity induced an increase in cortical bone volume and muscle force, and a topographic change of cortical thickness associated with muscular expression along a phenotypic trajectory that differed from the divergence induced by selective breeding. These results provide an experimental proof of concept that changes in locomotor behaviour and selective breeding might be inferred from long bones morphology in the fossil and archaeological record. These trends need to be explored in the archaeological record and further studies are required to explore the developmental changes behind these plastic responses

Nuclear export competence of pre-40S subunits in fission yeast requires the ribosomal protein Rps2

Ribosome biogenesis is an evolutionarily conserved pathway that requires ribosomal and nonribosomal proteins. Here, we investigated the role of the ribosomal protein S2 (Rps2) in fission yeast ribosome synthesis. As for many budding yeast ribosomal proteins, Rps2 was essential for cell viability in fission yeast and the genetic depletion of Rps2 caused a complete inhibition of 40S ribosomal subunit production. The pattern of pre-rRNA processing upon depletion of Rps2 revealed a reduction of 27SA2 pre-rRNAs and the concomitant production of 21S rRNA precursors, consistent with a role for Rps2 in efficient cleavage at site A2 within the 32S pre-rRNA. Importantly, kinetics of pre-rRNA accumulation as determined by rRNA pulse-chases assays indicated that a small fraction of 35S precursors matured into 20S-containing particles, suggesting that most 40S precursors were rapidly degraded in the absence of Rps2. Analysis of steady-state RNA levels revealed that some pre-40S particles were produced in Rps2-depleted cells, but that these precursors were retained in the nucleolus. Our findings suggest a role for Rps2 in a mechanism that monitors pre-40S export competence

SEASTAR: a mission to study ocean submesoscale dynamics and small-scale atmosphere-ocean processes in coastal, shelf and polar seas

High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer re-stratification. Small-scale processes particularly dominate in coastal, shelf and polar seas where they mediate important exchanges between land, ocean, atmosphere and the cryosphere, e.g., freshwater, pollutants. As numerical models continue to evolve toward finer spatial resolution and increasingly complex coupled atmosphere-wave-ice-ocean systems, modern observing capability lags behind, unable to deliver the high-resolution synoptic measurements of total currents, wind vectors and waves needed to advance understanding, develop better parameterizations and improve model validations, forecasts and projections. SEASTAR is a satellite mission concept that proposes to directly address this critical observational gap with synoptic two-dimensional imaging of total ocean surface current vectors and wind vectors at 1 km resolution and coincident directional wave spectra. Based on major recent advances in squinted along-track Synthetic Aperture Radar interferometry, SEASTAR is an innovative, mature concept with unique demonstrated capabilities, seeking to proceed toward spaceborne implementation within Europe and beyond

Identification of constrained sequence elements across 239 primate genomes

Noncoding DNA is central to our understanding of human gene regulation and complex diseases1,2, and measuring the evolutionary sequence constraint can establish the functional relevance of putative regulatory elements in the human genome3–9. Identifying the genomic elements that have become constrained specifically in primates has been hampered by the faster evolution of noncoding DNA compared to protein-coding DNA10, the relatively short timescales separating primate species11, and the previously limited availability of whole-genome sequences12. Here we construct a whole-genome alignment of 239 species, representing nearly half of all extant species in the primate order. Using this resource, we identified human regulatory elements that are under selective constraint across primates and other mammals at a 5% false discovery rate. We detected 111,318 DNase I hypersensitivity sites and 267,410 transcription factor binding sites that are constrained specifically in primates but not across other placental mammals and validate their cis-regulatory effects on gene expression. These regulatory elements are enriched for human genetic variants that affect gene expression and complex traits and diseases. Our results highlight the important role of recent evolution in regulatory sequence elements differentiating primates, including humans, from other placental mammals