Réduction de bruit et traitements paramétriques de la parole en large bande destinés à améliorer la compréhension des sujets malentendants

- Nous tentons de pallier les déficiences des aides auditives actuelles pour certaines surdités, par une plus grande prise en compte de la structure particulière du signal de parole. Pour cela nous voulons intégrer à une aide auditive des traitements paramétriques en bande élargie (0-8000 Hz). L'appareil doit savoir isoler les signaux qui bénéficieront de ces traitements. Il s'agit exclusivement des signaux de parole suffisamment peu bruités. Cette étude vise donc à déterminer les limites d'applicabilité des traitements paramétriques, après passage du signal dans un réducteur de bruit. Le réducteur de bruit basé sur un filtrage de Wiener est intégré au codeur. Les performances sont testées par l'évaluation, pour des normo-entendants et des malentendants : (1) de la capacité auditive (CA), via la mesure de la capacité de discrimination des indices acoustico-phonétiques de la parole en situation de bruit, (2) du confort auditif, par un test de préférence sur des phrases traitées et non traitées, prononcées dans diverses situations sonores significatives. Alors que la réduction de bruit isolée peut améliorer la CA chez certains normo-entendants uniquement, le codage paramétrique détériore la CA pour l'ensemble des sujets, ainsi que la qualité de la parole perçue par les malentendants

Strain-Tuning of 2D and 3D Charge-Density Waves in High-Temperature Superconducting YBa2_{2}Cu3_{3}Oy_{\rm{y}}

Uniaxial pressure experiments in underdoped YBa$_{2}$Cu$_{3}$O$_{\rm{y}}$ provide an efficient approach to the control of the competition between charge-density waves (CDWs) and superconductivity. It can enhance the correlation volume of ubiquitous short-range CDW correlations and above a critical value, even induce a long-range CDW order otherwise only accessible through the suppression of superconductivity by large magnetic fields. Here we use x-ray diffraction with access to large areas of reciprocal space to study the evolution of long- and short-range CDWs with in-plane strains and as a function of doping. This further allows us to precisely monitor in-situ the structural changes induced by uniaxial pressurization of the crystals for a precise strain estimation in measurements up to $-0.85 \%$ compression. Interestingly, we uncover direct evidence for a competition between long- and short-range CDWs and show that the long-range CDW modulation remains incommensurate at all investigated strains and temperatures, showing neither signs of discommensurations nor a pair-density wave component at $\lambda_{\rm{PDW}} = 2\lambda_{\rm{CDW}}$ below $T_c$. We discuss the impact of structural disorder and the relationship of our findings to previous reports on nematicity in high-temperature superconducting cuprates. More generally, our results underscore the potential of strain tuning as a powerful tool for probing and manipulating competing orders in quantum materials.Comment: I. Vinograd and S. M. Souliou contributed equally to this wor

Using strain to uncover the interplay between two- and three-dimensional charge density waves in high-temperature superconducting YBa₂Cu₃O_y

Uniaxial pressure provides an efficient approach to control charge density waves in YBa2Cu3Oy. It can enhance the correlation volume of ubiquitous short-range two-dimensional charge-density-wave correlations, and induces a long-range three-dimensional charge density wave, otherwise only accessible at large magnetic fields. Here, we use x-ray diffraction to study the strain dependence of these charge density waves and uncover direct evidence for a form of competition between them. We show that this interplay is qualitatively described by including strain effects in a nonlinear sigma model of competing superconducting and charge-density-wave orders. Our analysis suggests that strain stabilizes the 3D charge density wave in the regions between disorder-pinned domains of 2D charge density waves, and that the two orders compete at the boundaries of these domains. No signatures of discommensurations nor of pair density waves are observed. From a broader perspective, our results underscore the potential of strain tuning as a powerful tool for probing competing orders in quantum materials

Using strain to uncover the interplay between two- and three-dimensional charge density waves in high-temperature superconducting YBa2_2Cu3_3Oy_y

Uniaxial pressure provides an efficient approach to control charge density waves in YBa$_2$Cu$_3$O$_y$. It can enhance the correlation volume of ubiquitous short-range two-dimensional charge-density-wave correlations, and induces a long-range three-dimensional charge density wave, otherwise only accessible at large magnetic fields. Here, we use x-ray diffraction to study the strain dependence of these charge density waves and uncover direct evidence for a form of competition between them. We show that this interplay is qualitatively described by including strain effects in a nonlinear sigma model of competing superconducting and charge-density-wave orders. Our analysis suggests that strain stabilizes the 3D charge density wave in the regions between disorder-pinned domains of 2D charge density waves, and that the two orders compete at the boundaries of these domains. No signatures of discommensurations nor of pair density waves are observed. From a broader perspective, our results underscore the potential of strain tuning as a powerful tool for probing competing orders in quantum materials

X-Ray Structure of the Human Calreticulin Globular Domain Reveals a Peptide-Binding Area and Suggests a Multi-Molecular Mechanism

In the endoplasmic reticulum, calreticulin acts as a chaperone and a Ca2+-signalling protein. At the cell surface, it mediates numerous important biological effects. The crystal structure of the human calreticulin globular domain was solved at 1.55 Å resolution. Interactions of the flexible N-terminal extension with the edge of the lectin site are consistently observed, revealing a hitherto unidentified peptide-binding site. A calreticulin molecular zipper, observed in all crystal lattices, could further extend this site by creating a binding cavity lined by hydrophobic residues. These data thus provide a first structural insight into the lectin-independent binding properties of calreticulin and suggest new working hypotheses, including that of a multi-molecular mechanism