The human semicircular canal model of galvanic vestibular stimulation

A vector summation model of the action of galvanic stimuli on the semicircular canals has been shown to explain empirical balance and perceptual responses to binaural-bipolar stimuli. However, published data suggest binaural-monopolar stimuli evoke responses that are in the reverse direction of the model prediction. Here, we confirm this by measuring balance responses to binaural-monopolar stimulation as movements of the upper trunk. One explanation for the discrepancy is that the galvanic stimulus might evoke an oppositely directed balance response from the otolith organs that sums with and overrides the semicircular canal response. We tested this hypothesis by measuring sway responses across the full range of head pitch. The results showed some modulation of sway with pitch such that the maximal response occurred with the head in the primary position. However, the effect fell a long way short of that required to reverse the canal sway response. This indicates that the model is incomplete. Here, we examine alterations to the model that could explain both the bipolar and monopolar-evoked behavioural responses. An explanation was sought by remodelling the canal response with more recent data on the orientation of the individual canals. This improved matters but did not reverse the model prediction. However, the model response could be reversed by either rotating the entire labyrinth in the skull or by altering the gains of the individual canals. The most parsimonious solution was to use the more recent canal orientation data coupled with a small increase in posterior canal gain

From stratified wakes to rotor--stator flows by an SVV--LES method

International audienceWe extend a large-eddy simulation (LES) methodology, based on using the spectral vanishing viscosity (SVV) method to stabilize spectral collocation approximations, from the Cartesian to the cylindrical geometry. The capabilities of the SVV-LES approach are illustrated for two very different physical problems: (1) the influence of thermal stratification on the wake of a cylinder, and (2) the instabilities that develop in transitional and fully turbulent rotor-stator flows

Une nouvelle plateforme d’an alyse moléculaire pour le diagnostic médical basée sur la nanolithographie douce et la biodétection optique sans marquage

International audienceIn this article, we show that by biopatterning probe molecules at the nanoscale using soft lithography, protein biochips can be produced at a significantly lower cost for their use as a systematic method of molecular analysis for medical diagnosis purposes. The combination of multiplexed nanoscale microcontact printing and label-free optical detection using the principle of light diffraction is implemented for generating engineered glass slides for analysis, and a dedicated diffractive scanner for reading the multiplexed results of an assay.Une nouvelle plateforme d'analyse molé culaire pour le diagnostic mé dical basé e sur la nanolithographie douce et la biodé tection optique sans marquage Ré sumé : Dans ce travail nous montrons que la structuration à l'é chelle nanomé trique de biomolé-cules sondes par lithographie douce permet de fabriquer des puces à proté ines à un coû t de production suffisamment ré duit pour entrevoir leur utilisation dans le domaine de l'analyse molé culaire mé dicale. La combinaison d'un procé dé d'impression molé culaire et d'une dé tection optique sans marquage fondé e sur le principe de la diffraction de la lumiè re est mise en oeuvre afin de produire des supports d'analyse en verre comportant des motifs nanomé tri-ques et un scanner de diffraction qui permet la lecture d'un test biolo-gique multiplexé. Abstract: In this article, we show that by biopatterning probe molecules at the nanoscale using soft lithography, protein biochips can be produced at a significantly lower cost for their use as a systematic method of molecular analysis for medical diagnosis purposes. The combination of multiplexed nano-scale microcontact printing and label-free optical detection using the principle of light diffraction is implemented for generating engineered glass slides for analysis, and a dedicated diffractive scanner for reading the multiplexed results of an assay