Apport de la vision par ordinateur dans l'utilisabilité des neuroprothèses visuelles

L'OMS estime que 45 millions de personnes dans le monde sont aveugles. Avec le vieillissement de la population, ce chiffre ne cesse de progresser car la cécité touche majoritairement les personnes âgées. Les neuroprothèses visuelles ont pour objectif de restaurer une forme de vision. Ces systèmes convertissent les informations de la scène visuelle en percepts lumineux via des microstimulations électriques du système visuel. La perception visuelle ainsi générée consiste en un ensemble restreint de phosphènes. Ces systèmes sont, à ce jour, inutilisables dans un environnement naturel : l'information visuelle restituée est insuffisante pour que les personnes implantées puissent se déplacer, localiser des objets et les reconnaître. Au cours des dernières décennies, la vision par ordinateur a connu d'énormes avancées, grâce aux améliorations apportées aux algorithmes de traitement d'images et à l'augmentation de la puissance de calcul disponible. Il est désormais possible de localiser de manière fiable des objets, des visages ou du texte dans un environnement naturel. Or, la plupart des neuroprothèses visuelles intègrent une caméra facilement associable à un module de traitement d'images. Partant de ces constatations, nous avons montré qu'il est possible d'améliorer l'utilisabilité de ces systèmes, en utilisant des algorithmes de traitement d'images performants. En détectant des zones d'intérêt dans une scène naturelle et en les restituant à l'utilisateur par le biais d'un nombre limité de phosphènes, nos résultats indiquent qu'il est possible de restaurer des comportements visuo-moteurs adaptés : localisation d'objets, de visages ou encore de textes.The WHO estimates that 45 million people worldwide are blind. This figure is rapidly increasing because of the ageing of the world population, as blindness primarily affects elderly people. Visual neuroprostheses aim at restoring a sort of vision. These systems convert visual information captured by a camera into dots-like percepts via electrical microstimulation of the visual system. The evoked visual perception corresponds to a black and white image with a few dozen of pixels with gaps separating them. Although these systems give great hope to blind people, they are still inefficient in a natural environment: the restored visual information is too coarse to allow complex functions such as navigation, object localization and recognition, or reading at a convenient speed. Over the last decades, computer vision has been steadily improving, thanks to the development of new image processing algorithms and the increase of processing power. For instance, this is now possible to localize objects, faces or texts in real outdoor conditions. Interestingly, most of the current visual neuroprostheses include an external camera making it possible to process the input images in order to adapt the phosphenes display. In the current work, we showed that real-time image processing can improve the usability of low resolution visual neuroprostheses relying on the extraction of high-level information from the input images. Indeed, our results showed that the augmentation of the phosphene display with a limited number of phosphenes allows restoring visuomotor behaviors, such as localizing pertinent objects, faces or texts within a natural scene

Preserving syntactic correctness while editing mathematical formulas

GNU TeXmacs is a free software for editing scientific documents with mathematical formulas, which can also be used as an interface for many computer algebra systems. We present the design of a new experimental mathematical editing mode which preserves the syntactic correctness of formulas during the editing process (i.e. all formulas can be parsed using a suitable, sufficiently rich grammar). The main constraint is to remain as closely as possible to the existing presentation-oriented formula editor, which has the advantage of being very user friendly

Multiconfiguration GPR measurements for geometric fracture characterization in limestone cliffs (Alps)

Until now, geophysical methods have been rarely used to investigate vertical limestone cliffs, mainly due to the extreme conditions for data acquisition. Nevertheless, these techniques are the only available methods which could provide information on the internal state or a rock mass in terms of discontinuities, which play a major role in rock-fall hazards. In this case study, detailed GPR measurements were carried out on a test site with different acquisition configurations deployed on vertical cliff faces. Conventional 2D profiles, common midpoints (CMP) and transmission data were acquired to evaluate the potential of radar waves to improve the characterization of the geometry and properties of the main discontinuities (fractures) within the massif. The results show that the 3D geometry of fractures, which is a crucial parameter for stability assessment, can be retrieved by combining vertical and horizontal profiles performed along the cliff. CMP profiles acquired along the cliff allow a velocity profile to be obtained as a function of depth. Finally, transmission experiments, which generate complex radargrams, have provided valuable and quantitative information on the rock mass, through the modelling of the waves generated. On the other hand, a velocity tomography obtained from the first arrivals travelling through the rock mass from the transmitters to the receivers, shows an image of the investigated zone with a poor resolution

MapSense: Design and Field Study of Interactive Maps for Children Living with Visual Impairments

We report on the design process leading to the creation of MapSense, a multi-sensory interactive map for visually impaired children. We conducted a formative study in a specialized institute to understand children’s educational needs, their context of care and their preferences regarding interactive technologies. The findings (1) outline the needs for tools and methods to help children to acquire spatial skills and (2) provide four design guidelines for educational assistive technologies. Based on these findings and an iterative process, we designed and deployed MapSense in the institute during two days. It enables collaborations between children with a broad range of impairments, proposes reflective and ludic scenarios and allows caretakers to customize it as they wish. A field experiment reveals that both children and caretakers considered the system successful and empowering

MapSense: multi-sensory interactive maps for children living with visual impairments

We report on the design process leading to the creation of MapSense, a multi-sensory interactive map for visually impaired children. We conducted a formative study in a specialized institute to understand children’s educational needs, their context of care and their preferences regarding interactive technologies. The findings (1) outline the needs for tools and methods to help children to acquire spatial skills and (2) provide four design guidelines for educational assistive technologies. Based on these findings and an iterative process, we designed and deployed MapSense in the institute during two days. It enables collaborations between children with a broad range of impairments, proposes reflective and ludic scenarios and allows caretakers to customize it as they wish. A field experiment reveals that both children and caretakers considered the system successful and empowering

GNU TeXmacs: a scientific editing platform

3 pagesGNU TeXmacs is a free software for editing scientific documents, which can also be used as an interface for computer algebra systems. In this software demonstration we will briefly recall its main features and present some recent developments

Investigations for a Miniature Optical Frequency Reference Based on High-Contrast Sub-Doppler Resonance in a MEMS Cesium Vapor Cell

International audienceMany of modern quantum technologies require the development of high-performance and low-power consumption miniaturized devices such as laser systems, atomic clocks, magnetometers and other quantum sensors. These instruments are to date often based on the use of chip-size diode lasers and microfabricated (MEMS) cells filled with alkali atoms [1]. An interesting challenge concerns the development of miniaturized optical frequency references (OFR). Different approaches have been engaged in this direction. One of the most successful example is a rubidium microcell-based OFR, involving the two-photon spectroscopy technique. This approach has recently demonstrated a remarkable frequency stability level of 4.4×10–12 at 1 s [2]. The present study is focused on a simple alternative approach based on sub-Doppler spectroscopy (SDS) with counter-propagating light beams. We propose to use dual-frequency light beams with orthogonal linear polarizations and frequency difference w1–w2 = Dhfs, with Dhfs the frequency of the atom ground-state hyper-fine splitting. First dual-frequency sub-Doppler spectroscopy (DF SDS) experiments have been performed with cmscale cells [3,4]. In the present study, we present preliminary spectroscopy and frequency stability results of alaser stabilized using DF SDS with a Cs vapor microfabricated cell [5] (Fig.1a). An extended-cavity diode laser (ECDL) source and a Mach-Zehnder intensity EOM are used to obtain the dual-frequency light field. A forward beam goes through the cell and is then reflected by a mirror to create the backward beam

Patient perspectives on the role of community pharmacists for antidepressant treatment : a qualitative study

Objectives : Patients prescribed antidepressant drug treatment (ADT) for major depression report several needs in relation to their treatment, and a large proportion of these patients will end ADT prematurely. Community pharmacists may play an important role in monitoring ADT and supporting these patients. However, little is known about patient experiences of the services provided in community pharmacies. The objectives of this study were to 1) explore patients’ experiences with the services community pharmacists provide for ADT and 2) identify potential avenues for improvement of pharmacists’ services within the context of ADT. Methods : A qualitative descriptive exploratory study was conducted among individuals diagnosed with major depression who had initiated ADT at some point in the 12 months prior to their participation in the study. A total of 14 persons recruited in a local health centre and a community-based organization participated in individual interviews. A thematic analysis of the interview transcripts was conducted. Results : Pharmacists tend to concentrate their involvement in treatment at initiation and at the first refill when questions, uncertainties and side effects are major issues. Patients felt that the pharmacists’ contributions consisted of providing information and reassurance; in these respects, their needs were met. Participants had few ideas as to what additional services pharmacists could implement to improve patients’ experience with ADT. Patients’ sole expectations were that pharmacists extend this information role to the whole length of the treatment and enhance the confidentiality of discussions in pharmacy. Conclusion : Pharmacists should provide counselling throughout the entire treatment rather than passively waiting for patients to ask their questions. However, facilitation of open discussions may not be achieved unless confidentiality at pharmacies is secured

Excess mortality related to the August 2003 heat wave in France.

Objectives: From August 1st to 20th, 2003, the mean maximum temperature in France exceeded the seasonal norm by 11-12 degrees C on nine consecutive days. A major increase in mortality was then observed, which main epidemiological features are described herein. Methods: The number of deaths observed from August to November 2003 in France was compared to those expected on the basis of the mortality rates observed from 2000 to 2002 and the 2003 population estimates. Results: From August 1st to 20th, 2003, 15,000 excess deaths were observed. From 35 years age, the excess mortality was marked and increased with age. It was 15% higher in women than in men of comparable age as of age 45 years. Excess mortality at home and in retirement institutions was greater than that in hospitals. The mortality of widowed, single and divorced subjects was greater than that of married people. Deaths directly related to heat, heatstroke, hyperthermia and dehydration increased massively. Cardiovascular diseases, ill-defined morbid disorders, respiratory diseases and nervous system diseases also markedly contributed to the excess mortality. The geographic variations in mortality showed a clear age-dependent relationship with the number of very hot days. No harvesting effect was observed. Conclusions: Heat waves must be considered as a threat to European populations living in climates that are currently temperate. While the elderly and people living alone are particularly vulnerable to heat waves, no segment of the population may be considered protected from the risks associated with heat waves