Using CamiTK for rapid prototyping of interactive Computer Assisted Medical Intervention applications

Computer Assisted Medical Intervention (CAMI hereafter) is a complex multi-disciplinary field. CAMI research requires the collaboration of experts in several fields as diverse as medicine, computer science, mathematics, instrumentation, signal processing, mechanics, modeling, automatics, optics, etc

Medical image computing and computer-aided medical interventions applied to soft tissues. Work in progress in urology

Until recently, Computer-Aided Medical Interventions (CAMI) and Medical Robotics have focused on rigid and non deformable anatomical structures. Nowadays, special attention is paid to soft tissues, raising complex issues due to their mobility and deformation. Mini-invasive digestive surgery was probably one of the first fields where soft tissues were handled through the development of simulators, tracking of anatomical structures and specific assistance robots. However, other clinical domains, for instance urology, are concerned. Indeed, laparoscopic surgery, new tumour destruction techniques (e.g. HIFU, radiofrequency, or cryoablation), increasingly early detection of cancer, and use of interventional and diagnostic imaging modalities, recently opened new challenges to the urologist and scientists involved in CAMI. This resulted in the last five years in a very significant increase of research and developments of computer-aided urology systems. In this paper, we propose a description of the main problems related to computer-aided diagnostic and therapy of soft tissues and give a survey of the different types of assistance offered to the urologist: robotization, image fusion, surgical navigation. Both research projects and operational industrial systems are discussed

Antiretroviral-naive and -treated HIV-1 patients can harbour more resistant viruses in CSF than in plasma

Objectives The neurological disorders in HIV-1-infected patients remain prevalent. The HIV-1 resistance in plasma and CSF was compared in patients with neurological disorders in a multicentre study. Methods Blood and CSF samples were collected at time of neurological disorders for 244 patients. The viral loads were >50 copies/mL in both compartments and bulk genotypic tests were realized. Results On 244 patients, 89 and 155 were antiretroviral (ARV) naive and ARV treated, respectively. In ARV-naive patients, detection of mutations in CSF and not in plasma were reported for the reverse transcriptase (RT) gene in 2/89 patients (2.2%) and for the protease gene in 1/89 patients (1.1%). In ARV-treated patients, 19/152 (12.5%) patients had HIV-1 mutations only in the CSF for the RT gene and 30/151 (19.8%) for the protease gene. Two mutations appeared statistically more prevalent in the CSF than in plasma: M41L (P = 0.0455) and T215Y (P = 0.0455). Conclusions In most cases, resistance mutations were present and similar in both studied compartments. However, in 3.4% of ARV-naive and 8.8% of ARV-treated patients, the virus was more resistant in CSF than in plasma. These results support the need for genotypic resistance testing when lumbar puncture is performe

Comportement à la corrosion galvanique de matériaux composites à matrice d'alliage d'aluminium renforcée par des fibres de carbone haut-module

The service behaviour analysis of aluminium matrix composite material reinforced with carbon fibre involves evaluating the corrosion evaluation in a saline environment. The galvanic coupling between the carbon fibres and the aluminium alloy matrix plays a main part in the degradation of these composite materials. A local analysis by an in-situ experimental approach and a semi-analytical modelling are proposed to study the corrosion initiation and propagation at the fibre/matrix interfaces. The galvanic coupling and the aluminium carbide dissolution are involved and in competition in the localized degradation process. Thus the corrosion initiates perpendicularly to the fibre axis and then propagates along the fibre/matrix interface. These local mechanisms are compared to the global degradation of the material in which the fibre structure of the composite material has to be taken into account. A boundary element method simulation is used so that solutions can be proposed to reduce the galvanic corrosion kinetics between fibres and matrix and then improve the service behaviour of the composite materials.L'analyse de la corrosion en milieu salin de matériaux composites à matrice d'aluminium renforcée par des fibres de carbone fait partie de l'évaluation du comportement en service de ces matériaux. La dégradation par la corrosion dans les matériaux composites est accentuée par la présence d'un couple galvanique entre le renfort de carbone et l'alliage d'aluminium. L'amorçage et la propagation de la corrosion ont fait l'objet d'études expérimentales locales in situ à l'interface fibre/matrice ainsi que d'une modélisation semi-analytique. Il est mis en évidence que la corrosion s'amorce perpendiculairement à l'axe de la fibre puis se propage parallèlement à son axe le long de l'interface et par dissolution des carbures d'aluminium. Ces mécanismes locaux ont été comparés aux mécanismes globaux qui prennent en compte l'architecture fibreuse du composite. Une simulation par éléments frontières de la dissolution anodique a permis de proposer des solutions pour améliorer le comportement en service de ces matériaux composites

Comportement à la corrosion galvanique de matériaux composites à matrice d'alliage d'aluminium renforcée par des fibres de carbone haut-module.

L'analyse de la corrosion en milieu salin de matériaux composites à matrice d'aluminium renforcée par des fibres de carbone fait partie de l'évaluation du comportement en service de ces matériaux. La dégradation par la corrosion dans les matériaux composites est accentuée par la présence d'un couple galvanique entre le renfort de carbone et l'alliage d'aluminium. L'amorçage et la propagation de la corrosion ont fait l'objet d'études expérimentales locales in situ à l'interface fibre/matrice ainsi que d'une modélisation semi-analytique. Il est mis en évidence que la corrosion s'amorce perpendiculairement à l'axe de la fibre puis se propage parallèlement à son axe le long de l'interface et par dissolution des carbures d'aluminium. Ces mécanismes locaux ont été comparés aux mécanismes globaux qui prennent en compte l'architecture fibreuse du composite. Une simulation par éléments frontières de la dissolution anodique a permis de proposer des solutions pour améliorer le comportement en service de ces matériaux composites.The service behaviour analysis of aluminium matrix composite material reinforced with carbon fibre involves evaluating the corrosion evaluation in a saline environment. The galvanic coupling between the carbon fibres and the aluminium alloy matrix plays a main part in the degradation of these composite materials. A local analysis by an in-situ experimental approach and a semi-analytical modelling are proposed to study the corrosion initiation and propagation at the fibre/matrix interfaces. The galvanic coupling and the aluminium carbide dissolution are involved and in competition in the localized degradation process. Thus the corrosion initiates perpendicularly to the fibre axis and then propagates along the fibre/matrix interface. These local mechanisms are compared to the global degradation of the material in which the fibre structure of the composite material has to be taken into account. A boundary element method simulation is used so that solutions can be proposed to reduce the galvanic corrosion kinetics between fibres and matrix and then improve the service behaviour of the composite materials

La biominéralisation chez les coraux Scléractiniaires (étude de la matrice organique et des transports ioniques)

Les biominéraux, qui désignent les structures minérales rigides formées par les organismes, sont extrêmement répandus dans le monde vivant. Chez les coraux Scléractiniaires, le processus de biominéralisation conduit à la formation d'un exosquelette constitué de carbonate de calcium cristallisé sous la forme d'aragonite. La minéralisation est régulée, comme dans tous les biominéraux, par une fraction organique nommée matrice organique, et nécessite le transport d'ions calcium et de bicarbonate au niveau du site de formation du squelette. Ce travail de thèse consiste en l'étude de ces deux aspects de la biominéralisation chez les coraux Scléractiniaires. Grâce à l'utilisation d'anticorps polyclonaux dirigés contre la matrice organique extraite de l'exosquelette de corail, nous avons pu montrer que la biominéralisation chez les coraux est un processus biologiquement contrôlé et que l'ectoderme calicoblastique constitue le site de synthèse et de sécrétion de la matrice organique. Par des approches biochimique et moléculaire, nous avons entrepris l'étude des protéines de matrice des coraux Stylophora pistillata et Pavona cactus et obtenu six microséquences qui permettront de les caractériser. De plus, en réalisant un marquage des protéines de la matrice de corail avec des acides aminés radioactifs, nous avons mis en évidence la présence de protéines de matrice de faible poids moléculaire au sein d'un biominéral. Nous avons également montré qu'une BMP ("Bone Morphogenetic Protein") était exprimée chez le corail Acropora sp. au stade adulte et initié l'étude de son rôle potentiel dans la formation du squelette corallien. Concernant les apports ioniques nécessaires à la biominéralisation, nous nous sommes principalement intéressés aux mécanismes de transport du calcium. Nous avons ainsi mis en évidence la présence d'une calcium-ATPase dont la localisation au niveau de l'ectoderme calicoblastique suggère qu'elle est impliquée dans le transport de calcium vers le site de minéralisation.Biominerals are mineral structures made by organisms that are very widespread in the living world. In Scleractinian corals, biomineralization leads to the formation of an exoskeleton composed of aragonitic calcium carbonate. As in all biominerals, the mineralization process is controlled by an organic fraction called organic matrix and requires calcium and bicarbonate transport towards the mineralization site. This work focuses on these two aspects of the biomineralization process in Scleractinian corals. Using polyclonal antibodies raised against the organic matrix extracted from the coral exoskeleton, we showed that coral biomineralization is a biologically-controlled process and that the calicoblastic ectoderm is the site of organic matrix synthesis and secretion. Moreover, we studied matrix proteins from the corals Stylophora pistillata and Pavona cactus, and obtained six microsequences which will be used to characterize these proteins. In addition, by labelling coral organic matrix proteins with radioactive amino acids, we showed the presence of low molecular weight proteins within a biomineral. We also observed the expression of a BMP (Bone Morphogenetic Protein) in the adult coral Acropora sp. and have begun to study the potential role of this protein in coral skeletal formation. Concerning the supply of ions essential to biomineralization, we investigated the molecular mechanisms of calcium transport. We characterized a calcium-ATPase that is located in the calicoblastic ectoderm, suggesting that this protein is involved in calcium transport toward the mineralization site.NICE-BU Sciences (060882101) / SudocSudocFranceF

Nouvelle génération de capacités intégrées (influence des matériaux sur les performances diélectriques des capacités en couches minces)

Cette thèse porte sur l intégration de condensateurs accordables à base de BaxSr1-xTiO3 (BST), pour réaliser des dispositifs radiofréquences reconfigurables destinés aux antennes de téléphones portables. L enjeu industriel principal est d obtenir des condensateurs avec une forte accordabilité, de faibles pertes diélectriques et de faibles courants de fuite, en jouant sur la composition chimique du matériau et en contrôlant la chimie des défauts liés aux lacunes d oxygène. La stratégie adoptée dans cette étude pour atteindre cet objectif est de doper le BST par du Mn en substitution du Ti et par du Cu en addition. Une étude complète de ces deux cas de dopage simple, réalisée à la fois sur des céramiques et des couches minces synthétisées à partir des mêmes solutions sol-gel, a dévoilé des mécanismes différents d amélioration des propriétés diélectriques et électriques du matériau suivant le type de dopage. La complémentarité de ces deux dopants nous a alors conduit à explorer le codopage du BST en couche mince. Une architecture originale de codopage hétérogène a été mise en place, permettant de combiner les avantages des deux voies de dopage et de s approcher fortement des spécifications imposées par le cahier des charges industriel.This PhD work is about integration of BaxSr1-xTiO3 (BST) based tunable capacitors, in order to perform radiofrequency reconfigurable devices for cell phone antennas. The main industrial goal is to obtain capacitors with a high tunability, low dielectric losses and low leakage currents, by playing on the chemical composition of the material and by controlling the oxygen vacancy related defect chemistry. The strategy addressed in this study to reach this objective is doping the BST by Mn in substitution of Ti or by adding Cu. A full study of each case of doping, performed on both ceramics and thin films synthesized from the same sol-gel solutions, revealed different improvement mechanisms of the dielectric and electrical properties of the material according to the type of doping. The complementarity of the two doping ways has led us to investigate codoping of BST thin films. An original architecture of heterogeneous codoping has been set up, allowing to combine the benefits of each doping way and to closely meet the industrial specifications.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Surface segregation in Nb-doped BaTiO₃ films

We have used in situ photoemission spectroscopy to investigate Niobium doping in polycristalline BaTiO3. The valence band maximum position progressively shifts from 2.5 eV for undoped to 2.84 eV for Nb-doped films. Ceramics and single crystal have been investigated for comparison with thin films. Nb-doped BaTiO3 ceramics and Nb-doped SrTiO3 single crystal show higher Fermi level position indicating that our doped films are less conducting regarding their bulk parents. This was confirmed by impedance spectroscopy under variable temperature. Large amount of niobium is clearly observable at surface but the amount of dopant is drastically reduced below the near-surface region, as evidenced by depth profile. Therefore, we provide evidence of surface segregation which would explain the contrasted resistivity values reported in literature for such donor-doped films

Barrier height at (Ba,Sr)TiO3/Pt interfaces studied by photoemission

The interface formation of Nb-doped SrTiO3 single crystals and (Ba,Sr)TiO3 thin films with Pt has been studied by using photoelectron spectroscopy with in situ sample preparation. For the single crystal sample, a Schottky barrier height for electrons of 0.5–0.6 eV is determined after deposition of Pt in vacuum environment. After annealing in 0.05 Pa oxygen pressure, a strong increase in the barrier height to >=1.2 eV is observed. X-ray induced photovoltages of up to 0.7 eV are observed in this case and have to be taken into account for a proper determination of the barrier height. A subsequent annealing in vacuum reduces the barrier again. Hence, the barrier height can be reversibly switched between an oxidized state with a large barrier height and a reduced state with a low barrier height. Quantitative analysis of the barrier heights indicates that the changes are related to the changes of interfacial defect concentration. Due to the occurrence of a Ti3+ related signal, the defects are identified as oxygen vacancies. The same effects are observed at interfaces between Pt and (Ba,Sr)TiO3 thin films with a smaller absolute value of the barrier height in the oxidized state of ~1 eV. Deposition of (Ba,Sr)TiO3 onto a metallic Pt substrate also results in a barrier height of 1.0 eV

Experimental modal analysis and finite element model updating for structural health monitoring of reinforced concrete radioactive waste packages

International audienceThis study envisages the use of modal analysis for monitoring the structural health of radioactive waste packages. To this end, the calibration of a numerical model that describes the dynamic behavior is a critical issue for the success in damage detection. In this study, experimental modal analysis was conducted on a radioactive waste package mockup. The container was tested under different boundary conditions. Then, the experimental modal analysis data was used to update finite element models that describe the observed behaviors. The latter consists in the formulation of an optimization problem that minimizes the differences between the experimental and the numerical data. A two-step methodology is proposed for finite element model updating. First, a full factorial design of experiments allowed estimation of a set of parameters of the numerical model that minimize a cost function. Second, a genetic algorithm was conducted, wherein the initial population of parameters was generated as a function of that set of parameters obtained in the previous step. This study serves as preliminary step towards the implementation of a structural health monitoring based on modal analysis. Specific aspects for the implementation of a modal-based structural health monitoring system in a radioactive waste repository are also summarized