Interaction with In-Vehicle Electronic Systems. A Complete Description of a Neural Network Approach

International audienc

An adaptive and fully automatic method for estimating the 3D position of bendable instruments using endoscopic images

International audienceBackground. Flexible bendable instruments are key tools for performing surgical endoscopy. Being able to measure the 3D position of such instruments can be useful for various tasks, such as controlling automatically robotized instruments and analyzing motions. Methods. We propose an automatic method to infer the 3D pose of a single bending section instrument, using only the images provided by a monocular camera embedded at the tip of the endoscope. The proposed method relies on colored markers attached onto the bending section. The image of the instrument is segmented using a graph-based method and the corners of the markers are extracted by detecting the color transition along Bézier curves fitted on edge points. These features are accurately located and then used to estimate the 3D pose of the instrument using an adaptive model that allows to take into account the mechanical play between the instrument and its housing channel. Results. The feature extraction method provides good localization of markers corners with images of in vivo environment despite sensor saturation due to strong lighting. The RMS error on the estimation of the tip position of the instrument for laboratory experiments was 2.1, 1.96, 3.18 mm in the x, y and z directions respectively. Qualitative analysis in the case of in vivo images shows the ability to correctly estimate the 3D position of the instrument tip during real motions. Conclusions. The proposed method provides an automatic and accurate estimation of the 3D position of the tip of a bendable instrument in realistic conditions, where standard approaches fail

Biorder families, valued relations and preference modelling

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Positionnement 3-D d'un instrument flexible robotisé à l'aide d'une caméra monoculaire endoscopique: comparaison entre méthodes basées modèle et un apprentissage supervisé

International audienceLa connaissance précise de la configuration spatiale des instruments flexibles et actionnés est un facteur fondamental de réussite pour la chirurgie robotisée sans cicatrice. Pour ces opérations, les instruments de chirurgie qui sont insérés dans les canaux d'un guide flexible, possèdent des capacités de mouvements propres qu'il faut contrôler. Dans cet article, nous proposons une méthode permettant d'estimer la position des instruments de chirurgie de la plateforme Anubis (Karl Storz) en utilisant exclusivement les images endoscopiques délivrées par une caméra miniature embarquée. Cette plateforme est une réalisation de guide flexible pour la chirurgie robotisée où les instruments insérés dans les canaux possèdent trois degrés de liberté (translation, rotation et déflexion). Avec une caméra endoscopique, l'application directe des approches standards basées modèle pour la vision monoculaire échouent à fournir une précision suffisante de la position des instruments à cause essentiellement des incertitudes sur les paramètres. Pour surmonter cela, nous avons exploré une technique d'apprentissage supervisé. A cette fin, des marqueurs ont été fixés sur les instruments et servent à entrainer un classifieur de type Adaboost sur les images in vivo segmentées. Pour effectuer la validation, les indices visuels sont utilisés également comme données d'entrée à une fonction préalablement apprise sur une vérité terrain fournie par un capteur magnétique. Finalement, une comparaison avec deux autres méthodes confirme la précision du positionnement 3-D obtenue par notre méthode en situation réelle.</p

Effects of modulators of multidrug resistance on the expression of the MDR1 gene in human KB cells in culture

International audienceThe effect of four modulators of multidrug resistance (MDR) on the expression of the MDR1 gene was studied in two resistant variants of the KB cell lines, KB V1 and KB A1. This was done using a semi-quantitative assay based on mRNA reverse transcription coupled with polymerase chain reaction of the cDNA obtained. An automatic DNA sequencer was used for the measurement of the fluorescent amplification products and the MDR1 signal was compared to that of the beta-actin gene of the cells. After 24 h incubation with 15 microM of the modulators, MDR1 gene expression was slightly but significantly decreased by two of them, quinine and cyclosporine A, whereas verapamil and S-9788 had very little effect on this parameter. The effect were more pronounced in the KB A1 line than in the KB V1 line. The effect of quinine was studied over a longer time period (4-48 h) and was shown to be maximum at 24 h. These results favor the existence of a direct effect of some MDR reverters, especially quinine, on the expression of the MDR1 gene and could partially explain their modulating effect of MDR

Genotypic Characterization of Bradyrhizobium Strains Nodulating Small Senegalese Legumes by 16S-23S rRNA Intergenic Gene Spacers and Amplified Fragment Length Polymorphism Fingerprint Analyses

We examined the genotypic diversity of 64 Bradyrhizobium strains isolated from nodules from 27 native leguminous plant species in Senegal (West Africa) belonging to the genera Abrus, Alysicarpus, Bryaspis, Chamaecrista, Cassia, Crotalaria, Desmodium, Eriosema, Indigofera, Moghania, Rhynchosia, Sesbania, Tephrosia, and Zornia, which play an ecological role and have agronomic potential in arid regions. The strains were characterized by intergenic spacer (between 16S and 23S rRNA genes) PCR and restriction fragment length polymorphism (IGS PCR-RFLP) and amplified fragment length polymorphism (AFLP) fingerprinting analyses. Fifty-three reference strains of the different Bradyrhizobium species and described groups were included for comparison. The strains were diverse and formed 27 groups by AFLP and 16 groups by IGS PCR-RFLP. The sizes of the IGS PCR products from the Bradyrhizobium strains that were studied varied from 780 to 1,038 bp and were correlated with the IGS PCR-RFLP results. The grouping of strains was consistent by the three methods AFLP, IGS PCR-RFLP, and previously reported 16S amplified ribosomal DNA restriction analysis. For investigating the whole genome, AFLP was the most discriminative technique, thus being of particular interest for future taxonomic studies in Bradyrhizobium, for which DNA is difficult to obtain in quantity and quality to perform extensive DNA:DNA hybridizations

Highlights of nitrogen fixation research

At the present time, the precise taxonomial status of many strains classified as #Bradyrhizobium still remains unclear. There is a need to develop a reliable grouping method, specifying the genetic relationships between these strains. Phenotypic methods as auxanography or protein profiling did not prove valuable for classification of bradyrhizobia and were not in good agreement with phylogenetic data. The purpose of this work is to develop a strategy to analyse the diversity of bradyrhizobia and to identify genomic groups among our collection of strains isolated from 9 small legume species in Senegal. #B. japonicum, #B. elkanii$ and representatives of previously described groups by Moreira et al. (1993) and Dupuy et al. (1994) were included as references. Bacterial diversity was assessed by two different techniques, PCR-RFLP analysis of the IGS region between 16S and 23S rDNA (IGS) and the AFLP technique. Groupings of strains obtained by the two methodologies will be presented and compared. 16S rDNA PCR-RFLP analysis of strains representative of IGS clusters from small legumes was also performed. (Résumé d'auteur