Partitionning medical image databases for content-based queries on a grid

articleInternational audienceIn this article we study the impact of executing a medical image database query application on the grid. For lowering the total computation time, the image database is partitioned in subsets to be processed on different grid nodes. A theoretical model of the application computation cost and estimates of the grid execution overhead are used to efficiently partition the database. We show results demonstrating that smart partitioning of the database can lead to significant improvements in terms of total computation time

Polyphenol, polysaccharide and lactate extraction from pulping factory black liquor by ionic liquids

International audienceExtraction of polyphenols, polysaccharides and organic acids present in a liquor issued from a pulping factory, so-called black liquor, was studied using two ionic liquids trihexyltetradecylphosphonium chloride ([P 66614 ]Cl) and trihexyltetradecylphosphonium bromide ([P 66614 ]Br). The extraction of each of the three compounds mentioned above was reported as a function of the dilution of the initial black liquor, the volume ratio of liquor vs. ionic liquid, and the initial pH of the black liquor. Polyphenols and polysaccharides were quantitatively extracted at room temperature with both ionic liquids. Extraction of lactate anions was found to be low, exhibiting distribution coefficients below 8 in all cases

A biomechanical model of swallowing for understanding the influence of saliva and food bolus viscosity on flavour release

International audienceAfter swallowing a liquid or a semi-liquid food product, a thin film responsible for the dynamic profile of aroma release coats the pharyngeal mucosa. The objective of the present article was to understand and quantify physical mechanisms explaining pharyngeal mucosa coating. An elastohydrodynamic model of swallowing was developed for Newtonian liquids that focused on the most occluded region of the pharyngeal peristaltic wave. The model took lubrication by a saliva film and mucosa deformability into account. Food bolus flow rate and generated load were predicted as functions of three dimensionless variables: the dimensionless saliva flow rate, the viscosity ratio between saliva and the food bolus, and the elasticity number. Considering physiological conditions, the results were applied to predict aroma release kinetics. Two sets of conditions were distinguished. The first one was obtained when the saliva film is thin, in which case food bolus viscosity has a strong impact on mucosa coating and on flavour release. More importantly, we demonstrated the existence of a second set of conditions. It was obtained when the saliva film is thick and the food bolus coating the mucosa is very diluted by saliva during the swallowing process and the impact of its viscosity on flavour release is weak. This last phenomenon explains physically in vivo observations for Newtonian food products found in the literature. Moreover, in this case, the predicted thickness of the mix of food bolus with saliva coating the mucosa is approximately of 20 µm; value in agreement with orders of magnitude found in the literature

Segmentation vidéo et suivi d'objets par maillage déformable : gestion des discontinuités de mouvement

Nous proposons un nouvel algorithme de maillage actif qui place les arêtes du maillage sur les discontinuités de mouvement. Le mouvement intérieur à chaque cellule est estimé par mise en compétition des estimations avant et arrière. Cette approche permet le déplacement des noeuds du maillage sans avoir à remailler les zones occultées ou découvertes

Medical Image Content-Based Queries using the Grid

International audienceComputation and data grids have encountered a large success among the scientific computing community in the past few years. The medical imaging community is increasingly aware of the potential benefit of these technologies in facing today medical image analysis challenges. In this paper, we report on a first experiment in deploying a medical application on a large scale grid testbed. Our pilot application is a hybrid metadata and image content-based query system that manipulates a large data set and for which image analysis computation can be easily parallelized on several grid nodes. We analyze the performances of this algorithm and the benefit brought by the grid. We further discuss possible improvements and future trends in porting medical applications to grid infrastructures

SIMONE: a realistic neural network simulator to reproduce MEA-based recordings

International audienceContemporary multielectrode arrays (MEAs) used to record extracellular activity from neural tissues can deliver data at rates on the order of 100 Mbps. Such rates require efficient data compression and/or preprocessing algorithms implemented on an application specific integrated circuit (ASIC) close to the MEA. We present SIMONE (Statistical sIMulation Of Neuronal networks Engine), a versatile simulation tool whose parameters can be either fixed or defined by a probability distribution. We validated our tool by simulating data recorded from the first olfactory relay of an insect. Different key aspects make this tool suitable for testing the robustness and accuracy of neural signal processing algorithms (such as the detection, alignment, and classification of spikes). For instance, most of the parameters can be defined by a probabilistic distribution, then tens of simulations may be obtained from the same scenario. This is especially useful when validating the robustness of the processing algorithm. Moreover, the number of active cells and the exact firing activity of each one of them is perfectly known, which provides an easy way to test accuracy

A lubrication analysis of pharyngeal peristalsis: application to flavour release.

International audienceAfter eating a liquid or a semi-liquid food product, a thin film responsible for the dynamic profile of aroma release coats the pharyngeal mucosa. The aim of this article was to analyse the fluid mechanics of pharyngeal peristalsis and to develop a simple biomechanical model in order to understand the role of saliva and food bolus viscosity on the coating of pharyngeal mucosa. We began by analysing the physiology and the biomechanics of swallowing in order to determine relevant model assumptions. This analysis of the literature clarified the types of mechanical solicitations applied on the food bolus. Moreover, we showed that the pharyngeal peristalsis in the most occluded region is equivalent to a forward roll coating process, the originality of which is lubrication by a film of saliva. A model based on the lubrication theory for Newtonian liquids was developed in dimensionless form. The parametric study showed the strong influence of relative saliva thickness on the food bolus coating. A specific experimental device was designed that confirms the model predictions. Two sets of conditions that depend on the relative thickness of saliva were distinguished. The first is characterised by a relatively thin film of saliva: food bolus viscosity has a strong impact on mucosa coating. These phenomena are well represented by the model developed here. The second is obtained when the saliva film is relatively thick: hydrodynamic mixing with saliva, interdiffusion or instabilities may govern mucosa coating. Finally, these results were extrapolated to determine the influence of food bolus viscosity on the dynamic profile of flavour release according to physiological parameters

Segmentation et suivi de mouvement d'objets déformables par région active

Nous proposons un nouveau type de modèle déformable appelé région active pour la segmentation avec connaissance d'un modèle géométrique. Le modèle consiste en une région dotée de propriétés d'élasticité qui garantissent des déformations cohérentes, en particulier dans le cas d'un objet aux interfaces multiples. Pour conserver cependant un contrôle précis de la régularité des interfaces, chacune d'entre elles possède une flexibilité propre, analogue à celle d'un contour actif. Le modèle de région active est mis en oeuvre pour la segmentation conjointe des interfaces du ventricule gauche du coeur en IRM

Un modèle de thorax respirant pour l'évaluation d'algorithmes de reconstruction d'organes en mouvement par tomographie virtuelle

Nous proposons un système de tomographie dynamique et virtuel du thorax destiné à mettre en évidence l'effet du mouvement respiratoire sur la reconstruction de coupes. Ce système est basé sur un modèle anatomique des structures du thorax animé de manière réaliste à partir de fonctions de déformation volumiques dites de forme libre. Des projections X sont simulées à partir de ce modèle dynamique dans des configurations conformes à celles utilisées sur les tomographes dynamiques. La reconstruction à partir des projections montre l'impact du mouvement respiratoire sur la qualité des coupes reconstruites