Sound-Evoked Radial Strain in the Hearing Organ

AbstractThe hearing organ contains sensory hair cells, which convert sound-evoked vibration into action potentials in the auditory nerve. This process is greatly enhanced by molecular motors that reside within the outer hair cells, but the performance also depends on passive mechanical properties, such as the stiffness, mass, and friction of the structures within the organ of Corti. We used resampled confocal imaging to study the mechanical properties of the low-frequency regions of the cochlea. The data allowed us to estimate an important mechanical parameter, the radial strain, which was found to be 0.1% near the inner hair cells and 0.3% near the third row of outer hair cells during moderate-level sound stimulation. The strain was caused by differences in the motion trajectories of inner and outer hair cells. Motion perpendicular to the reticular lamina was greater at the outer hair cells, but inner hair cells showed greater radial vibration. These differences led to deformation of the reticular lamina, which connects the apex of the outer and inner hair cells. These results are important for understanding how the molecular motors of the outer hair cells can so profoundly affect auditory sensitivity

Mean field and corrections for the Euclidean Minimum Matching problem

Consider the length $L_{MM}^E$ of the minimum matching of N points in d-dimensional Euclidean space. Using numerical simulations and the finite size scaling law $= \beta_{MM}^E(d) N^{1-1/d}(1+A/N+... )$, we obtain precise estimates of $\beta_{MM}^E(d)$ for $2 \le d \le 10$. We then consider the approximation where distance correlations are neglected. This model is solvable and gives at $d \ge 2$ an excellent ``random link'' approximation to $\beta_{MM}^E(d)$. Incorporation of three-link correlations further improves the accuracy, leading to a relative error of 0.4% at d=2 and 3. Finally, the large d behavior of this expansion in link correlations is discussed.Comment: source and one figure. Submitted to PR

Class III myosins shape the auditory hair bundles by limiting microvilli and stereocilia growth.

International audienceThe precise architecture of hair bundles, the arrays of mechanosensitive microvilli-like stereocilia crowning the auditory hair cells, is essential to hearing. Myosin IIIa, defective in the late-onset deafness form DFNB30, has been proposed to transport espin-1 to the tips of stereocilia, thereby promoting their elongation. We show that Myo3a(-/-)Myo3b(-/-) mice lacking myosin IIIa and myosin IIIb are profoundly deaf, whereas Myo3a-cKO Myo3b(-/-) mice lacking myosin IIIb and losing myosin IIIa postnatally have normal hearing. Myo3a(-/-)Myo3b(-/-) cochlear hair bundles display robust mechanoelectrical transduction currents with normal kinetics but show severe embryonic abnormalities whose features rapidly change. These include abnormally tall and numerous microvilli or stereocilia, ungraded stereocilia bundles, and bundle rounding and closure. Surprisingly, espin-1 is properly targeted to Myo3a(-/-)Myo3b(-/-) stereocilia tips. Our results uncover the critical role that class III myosins play redundantly in hair-bundle morphogenesis; they unexpectedly limit the elongation of stereocilia and of subsequently regressing microvilli, thus contributing to the early hair bundle shaping

I Dalarna

Affisch för teaterföreställningarna 1. Den häftige friaren och 2. I Dalarne på Åbo Svenska Teater 30.10.185

Alexis et Justine : comédie lyrique en deux actes et en prose, mêlée d'ariettes / Par M. de Monvel ; Musique de M. Desaides

Sólo libreto, sin músicaReprésentée pour la première fois par les Comédiens Italiens ordinaires du Roi, devant Leurs Majestés, à Versailles le 14 Janvier 1785 ...Sign.: A-D4, E1Port. con viñeta xil

Alexis et Justine : comédie lyrique en deux actes et en prose, mêlée d'ariettes / Par M. de Monvel ; Musique de M. Desaides

Sólo libreto, sin músicaReprésentée pour la première fois par les Comédiens Italiens ordinaires du Roi, devant Leurs Majestés, à Versailles le 14 Janvier 1785 ...Sign.: A-D4, E1Port. con viñeta xil

Blaise et Babet ou La suite des trois fermiers : comédie en deux actes, mêlée d'ariettes / Par M. de Monvel ; Musique de M. De Zedes

Sólo libreto, sin músicaReprésentée pour la première fois par les Comédiens Italiens ordinaires du Roi, devant leurs Majestés, à Versailles, le 4 Avril, et à Paris le 30 Juin 1783Sign.: A-D4, E2Port. con viñeta xil