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International audience; The current study focused on modelling of micro-deep drawing of aluminium single crystals using a physically-based crystal plasticity model. The approach consisted in modelling the gauge area located at the centre of the crystals with boundary conditions extracted from displacement fields measured experimentally by digital image correlation. Thanks to three different geometries of samples, three loading paths were considered: uniaxial tension, plane strain tension and equi-biaxial tension. Comparisons between simulations and experimental observations were performed in terms of displacement fields, strain fields and slip traces. Data obtained from the simulations also allowed analysis of the results in terms of crystal rotation, dislocation density evolution and accumulated slip. Reasonable agreement between experimental observations and simulations was generally obtained, except for the prediction of strain localisation which was only correct in the case of uniaxial and plane strain tension. Discrepancies and validity of the modelling approach are then discussed in terms of experimental inaccuracies and numerical approximations.

The Ce-rich part of Ce–Pt phase diagram has been investigated by means of differential thermal analysis (DTA), X-ray diffraction (XRD), optical and electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Two new intermediate phases, Ce5Pt3 and Ce5Pt4, have been discovered and found to crystallize with tetragonal Pu5Pd3-type structure and orthorhombic Ge4Sm5-type structure, respectively. All the Ce-rich compounds of the system were found to crystallize with a peritectic type formation. We have determined the temperatures of the peritectic plateaus and established the liquidus curves up to 1500 °C.

National audience; L’ambition de doter la France d’un centre de traitement des tumeurs par faisceaux d’ions carbone est née, à la fin des années 1990, de la rencontre à l’Université Claude Bernard Lyon 1 de quelques médecins et physiciens, convaincus que la France avait toutes les capacités médicales et scientifiques pour initier un tel programme. Ce projet de « carbonethérapie » prit le nom de projet ETOILE (Espace de Traitement Oncologique par Ions Légers en Europe) au début des années 2000. Pour comprendre pourquoi il n’a pas été réalisé et évaluer les chances pour qu’il le soit un jour, il faut analyser les enjeux, les difficultés et les avantages de la carbonethérapie, comparée à la protonthérapie et aux formes les plus avancées de la radiothérapie.

The crystal structures and structure transformations of ZrAu have been investigated by means of neutron powder diffraction on as-cast ingots placed in evacuated quartz tubes to avoid oxidation. In the temperature range 300–1273 K, two structure transformations have been observed and confirmed by resistivity measurement results. The first one occurs at about 670 K and is a second-order transition as it does not yield any differential thermal analysis (DTA) event. The second one occurs at 840 K as previously reported. In each temperature interval, a complete structure model compatible with collected data was derived and used for Rietveld analysis. Between room temperature and 670 K, the structure is found triclinic (P 1 , a=11.537(8) A, b=4.841(1) A, c=11.507(7) A, α=87.42(1)°, β=104.82(1)° and γ=92.41(2)° at 300 K). Above 670 K and below 840 K, the structure is satisfactorily described in the monoclinic space group P2/m (a=11.695(16) A, b=4.828(3) A, c=11.719(18) A, β=107.090(17)° at 773 K) and finally between 840 and 1273 K, it is tetragonal, closely related to the A2-type structure (P4/mmm, a=4.835(2) A and c=3.416(3) A).

International audience; Hadron therapy is an innovative cancer treatment method based on the acceleration of light ions at high energy. In addition to their interesting profile of dose deposition, which ensures accurate targeting of localized tumors, carbon ions offer biological properties that lead to an efficient treatment for radio-and chemo-resistant tumors and to provide a boost for tumors in hypoxia. This paper is a short review of the progress in theoretical, experimental, fundamental and applied research, aiming at understanding the origin of the biological benefits of light ions better. As a limit of such a vast and multidisciplinary domain, this review adopts the point of view of the physicists, leaning on results obtained in connection with CIMAP's IRRABAT platform. 1. Introduction Interaction of fast ions with biological systems constitutes one aspect of the interdisciplinary researches performed with ion-beam facilities. This domain is as rich as it is complex since it encompasses several orders of magnitude in both space and time. The shortest space and time scale corresponds to atomic collisions, which may be as short as 10 −18 s for the interaction of fast ions with individual atoms. At the opposite end of this domain, late effects – like cancer induction, chromosomal instability or organ dysfunctions – may appear or remain several years after irradiations. While irradiations may be limited to a very localized region, the whole behavior of an organ may be affected, possibly leading to human death, in particular when the irradiation dose and spatial extension are high. Between these two extreme scales, stands a great number of mechanisms, including for instance: the transport of the primary ejected electrons, the relaxation of the ionized and excited molecules, which may lead to direct damage in biological targets and to radical species and associated biochemical reactions. These early physical and chemical stages are followed by numerous and complex cell responses, such as the triggering of mechanisms to check DNA, to repair its damage, to manage the oxidative stress or to induce cell death. The numerous biological endpoints that have been studied reveal the complexity and the diversity of this biological response. These endpoints may involve particular structures of cells at the molecular scale (tracking of protein activities, damage in DNA, protein or lipid) or at the sub-cellular scale (chromosomes, nucleus, membranes, mitochondria.. .) and may concern cell organization (3D cell culture, tissues, organs, body). The domain of low doses

International audience; Patient-specific respiratory motion modeling may help to understand pathophysiology and predict therapy planning. The respiratory motion modifies the shape and position of internal organs. This may degrade the quality of such medical acts as radiotherapy or laparoscopy. Predicting the breathing movement is complex, and it is considered as one of the most challenging areas of medical research. This paper presents a biomechanical model of the respiratory system, based on the finite element method (FEM), including the biomechanical behavior of the diaphragm as well as rib kinematics computations, on the assumption that breathing is controlled by two independent actors: the thorax and diaphragm muscles. In order to predict the type of the (geometrical or material) nonlinearities, a quantitative comparison of the clinical data was applied on 12 patients. We propose two nonlinear hyperelastic models: the Saint-Venant Kirchhoff and Mooney–Rivlin models. Our results demonstrate that the nonlinear hyperelastic Mooney–Rivlin model of the diaphragm behaves similarly to the linear elastic model with large displacement (Saint-Venant Kirchhoff). The results suggest that the approach of small strains (within the large displacement) may be globally maintained in the modeling of the diaphragm, and demonstrate that the accuracy of the proposed FEM is capable to predict the respiratory motion with an average surface error in a diaphragm/lungs region of interest contact of 2. 0 ± 2. 3 mm for the contact surface between lungs and diaphragm. The comparison study between the FEM simulations and the CT scan images demonstrates the effectiveness of our physics-based model.

A previously reported structure proposal for Pb-deficient PbWO4 (Pb7W8O32−x, space group P4/nnc) could be rejected based on neutron powder diffraction data. A new model in agreement with X-ray and neutron diffraction data is proposed (tetragonal, tP48, space group P-4-h10g2dcba, a=7.7208(1), c=12.0417(2) A). It is a superstructure of the scheelite type with partial vacancies on a one-fold lead site, leading to the composition Pb7.5W8O32.

The structural peculiarities and the influence of additional doping of PbWO 4 crystals with Nb, Bi, Yb, and Mg ions have been investigated. It is shown that even a small amount of specific impurities leads to an important redistribution of the structural point defects, the radiating centres, and their properties in the crystals. The data have been used for further optimization of PbWO 4 scintillator development for electromagnetic calorimeter (ECAL) of compact muon solenoid (CMS) at CERN.

The crystalline structure and electrical resistivity of the new yellow molybdenum bronze GdMo16O44 are presented. Single crystal X-ray diffraction analysis indicate a rhombohedral space group R 3 with lattice parameters a = 10.780(2) A and c = 27.493(4) A . The outstanding features are; i) all polyhedra share corners with their neighbours; ii) the structure is built up from clusters of eight MoO6 octahedra separated from other clusters and from GdO8 cubes by MoO4 tetrahedra; iii) six-fold and four-fold coordinated molybdenum atoms have a valence state close to +5 and +6 respectively. As expected by the structural results the compound is found semiconducting.

International audience; We present a method to track a patient and the equipment in a radiotherapy treatment room, by exploiting the information in the treatment plan, enriched with other elements such as visual, geometric and \quotes{semantic} information. Using all these information items, and a generic model, a virtual environment of the scene is created, with maximum precision. The images resulting from video sequences with several cameras are also used to confront the filmed information on the scene and its numerical representation. The method is based on the features of the scene elements, and on a fuzzy formalism. The feasibility of the method is being quantitatively evaluated in the absence of treatment, to be further exploited in a module for external control by video in real conditions.; Nous présentons une méthode de suivi d'un patient et de l'équipement dans une salle de traitement par radiothérapie, qui exploit les informations contenues dans le plan de traitement, enrichies d'autres informations visuelles, géométriques et « sémantiques ». En utilisant toutes ces informations, et un modèle générique, un environnement virtuel de la scène est créé, avec un maximum de précision. Les images acquises à partir d'un système d'acquisition composé de plusieurs caméras vidéo sont également utilisées afin de confronter les informations « filmées » dans la scène et celles contenues dans la représentation numérique. La méthode est basée sur les caractéristiques des éléments de la scène, et un formalisme « floue ». La faisabilité de la méthode est d'abord évalué hors traitement, afin d'être exploitée par la suite dans un module de contrôle externe par vidéo dans de conditions réelles.

This paper describes an extension of the “lazy” rational arithmetic (LEA) presented in [1]. A lazy arithmetic is an optimized version of the usual exact arithmetics used in Symbolic Calculus, in Computational Geometry or in many other fields. We present a method originating from modular arithmetic for storing lazy numbers in hash-tables. This method uses results from the wellstudied technique of “hash coding” ([4]) to compute efficient “keys” for lazy numbers. In fact, such keys may be used to hash code lazy numbers, or data containing lazy numbers, such as vertices or line segments in Computational Geometry.

International audience; This paper introduces the application of microdeep drawing of single and multicrystals of aluminium in order to identify parameters of micro-mechanical models. The information obtained experimentally is abundant: loaddisplacement curves of the punch, the evolution of grain orientation, mapping deformations throughout the test. All this experimental data was used to validate the multiscale models introduced in a finite element code for loading paths ranging from biaxial tensile to simple tensile.

Treatment of cancerous tumours in the lungs by ha- drontherapy requires precise knowledge of the position of the tumour throughout the treatment. A biomechani- cal model of the respiratory system allows the tracking of the tumour. This model requires the de nition of boundary conditions, set by the skin of the chest. In this sense, the objective of this article concerns the establishment of the complete processing chain for a continuous monitoring of the skin of the thorax (from neck to abdomen) through the use of a multi-modal non-invasive real-time system. A geometric model of reference of the thorax is rst created from preoperative medical data (CT, MRI). Then, during several respiratory cycles, this geome- tric model (surface mesh) is deformed to match the images of the thorax acquired by two cameras (above and lateral side). We achieve an accuracy around one millimeter, corresponding to the precision of the 3D images as well as the one of the used cameras, with a treatment rate of 6 frames per second., Le traitement par hadronthérapie des tumeurs cancéreuses présentes dans les poumons nécessite la connaissance précise de la position de la tumeur tout au long du traitement. Dans ce sens, des travaux visent l'élaboration d'un modèle biomécanique du système respiratoire qui permettrait le suivi de cette tumeur. Par contre, ce modèle nécessite la définition des conditions limites établies par la peau du thorax. L'objectif de cet article concerne ainsi la mise en place de la chaîne de traitement complète permettant le suivi continu de la peau du thorax (du cou jusqu'à l'abdomen) au cours du traitement, par l'utilisation d'un système multi-modal, non invasif et temps réel. Un modèle géométrique de référence du thorax est tout d'abord créé à partir des données médicales pré-opératoires du patient (scanner, IRM). Puis, durant plusieurs cycles respiratoires, ce modèle géométrique (maillage surfacique) est déformé pour correspondre aux images du thorax du patient issues de deux caméras (une au dessus, et l'autre sur le côté). Nous obtenons une précision de l'ordre du millimètre, correspondant à la précision des images 3D et des caméras utilisées, avec un traitement de 6 images par seconde.

Single crystals of PbWO 4 have been obtained by the Czochralski method. Atomic structure has been determined by X-ray diffraction (scheelite type, tetragonal, space group I 4 1 / a , a = 5.456(2), c = 12.020(2) A). With PbO deficiency in the melt, crystallization occurred with a new atomic arrangement determined by X-ray diffraction (tetragonal, space group P 4/ nnc , a = 7.719(2), c = 12.018(2) A). Unit cell parameter a related to the scheelite type by a factor of √2. Oxygen and lead sites not fully occupied gave a formula Pb 7 W 8 O (32− x ) with x = 3.2(8).

A new stable phase Tl4Ag24−x Te15−y in the ternary TlAgTe system has been identified by X-ray diffraction on single crystals. The space group is P 6 and the lattice parameters are a = 1.1418(4) nm and c = 0.9220(1) nm with one formula per unit cell (Z = 1). The structure is described as an arrangement of two types of channels parallel to the [001] direction. Two-thirds of these channels are hexagonal and built up with silver and tellurium atoms, hosting thallium atoms. One-third are octahedral chains of silver atoms with centres statistically occupied by tellurium atoms. In addition, the refinement indicates partial occupation of some silver positions.

A new stable phase in the ternary TlAgTe system has been identified. X-ray diffraction examination of single crystals was used to establish the crystal structure of Tl4Ag18Te11. The cubic space group is F 4 3m and the lattice parameter is a = 1.8717(8) nm, Z = 8. The relationship to the cubic BaHg11-type structure and the In2Te3-type structure are established. The structure is described as a three-dimensional array of large channels of silver and tellurium atoms hosting linear chains of thallium atoms. These independent channels are built up with cubes and square antiprisms stacked along the fourfold axis and they are connected by smaller channels built up with smaller square antiprisms and cubes hosting tellurium atoms.

A new stable phase has been identified in the Nd-Fe-Si system. X-ray diffraction examination of single crystals was used to establish the crystal structure of Nd 6 Fe 13 Si. The tetragonal space group is I 4/ mcm and the lattice parameters are a = b = 0.8034(3)nm, c = 2.278(1)nm. The crystal structure is an ordered version of Nd 6 Ga 3 Fe 11 .Magnetic measurements show an antiferromagnetic behaviour.

A new stable phase in the NdFe system has been identified. X-ray diffraction examination of single crystals was used to establish the crystal structure of Nd5Fe17. The hexagonal space group is P6 3 mcm and the lattice parameters are a = 2.0214(8) nm, c = 1.2329(8) nm, Z = 12. The Nd5Fe17 structure is built up of layers which are a tessellation of triangles, pentagons, hexagons and heptagons. The stacking of layers forms antiprisms. Clusters of neodymium atoms only are made of trigonal antiprisms or regular octahedra stacked upon each other to form infinite columns. Each neodymium cluster is surrounded by a first ring of nine pentagonal antiprisms centred by iron atoms and a second ring of 12 antiprisms with hexagonal and heptagonal faces centred by neodymium atoms.

Phase transformations and crystal structures in the ternary compounds GdNi(1−x)Cux were examined with x parameter variation from 0 to 0.2 using X-ray diffraction on powders and single crystals. Depending from the heat treatment two structures were characterized for x = 0.1 depending from the heat treatment: a monoclinic CrB variant for the as-cast phase (space group Pm, Z = 16 , a = 7.619 ( 1 ) , b = 8.543 ( 2 ) , c = 10.990 ( 7 ) A , β = 112.8 ( 3 ) ° ) and a monoclinic βCaCu variant for the annealed phase (space group P-1, Z = 40 , a = 17.723 ( 9 ) , b = 4.270 ( 2 ) , c = 10.959 ( 3 ) A , β = 95.22 ( 6 ) ° ).

Phase transformations and crystal structures in the ternary compounds NdNi (1− x ) Cu x were examined with x parameter variation from 0 to 0.3 using X-ray diffraction on powders and single crystals. Three phases were characterized: an orthorhombic CrB type for x values between 0 and 0.175, a new monoclinic variant of the CrB type for x values ranging from 0.175 to 0.20, an orthorhombic FeB type for x values larger than 0.20. The unit cell parameters of the monoclinic variant (space group Pm, Z =16, a =7.603(1), b =8.732(4), c =11.146(3) A, β =109.91(2)°) are related to the orthorhombic CrB type parameters by the relations a m =2 a , b m =2 c , c m = b − a .

Single crystals of PbWO 4 have been obtained by the Czochralski method. Atomic structure has been determined by X-ray diffraction (scheelite type, tetragonal, space group I 4 1 / a , a = 5.456(2), c = 12.020(2) A). With PbO deficiency in the melt, crystallization occurred with a new atomic arrangement determined by X-ray diffraction (tetragonal, space group P 4/ nnc , a = 7.719(2), c = 12.018(2) A). Unit cell parameter a related to the scheelite type by a factor of √2. Oxygen and lead sites not fully occupied gave a formula Pb 7 W 8 O (32− x ) with x = 3.2(8).

Systems based on exact arithmetic are very slow. In practical situations, very few computations need be performed exactly as approximating the results is very often sufficient. Unfortunately, it is impossible to know at the time when the computation is called for whether an exact evaluation will be necessary or not. The arithmetic library presented here achieves laziness by postponing any exact computation until it is proved to be indispensable. This yields very substantial gains in performance while allowing exact decisions. The lazy arithmetic techniques are presented in the context of rational computations, using the field of computational geometry as a background. >

This special issue contains a selection of papers presented during the international conference “Real Numbers and Computers”, Saint-Etienne, France, April 1995.

The introduction of Cu in the CeNi compound maintains the same crystallographic CrB-type structure up to CeNi 0.85 Cu 0.15 . The crystallographic structure of several compositions in the neighbourhood of this limit has been determined from single crystals in a 4-circle diffractometer. The thermal expansion coefficients of CeNi 0.9 Cu 0.1 behave similar to those of CeNi. The Cu substitution disturbs the intermediate valence behaviour of CeNi, inducing non-zero magnetic moments at low temperatures and suggesting a cluster-glass behaviour.

JUCS - Journal of Universal Computer Science Volume Nr. 1 Issue Nr. 7

Purpose/Objective: We propose a module to monitor a treatment room using video cameras in order to assist and reassure the radiation therapist and to record the sequence of events during the treatment delivery process. This module will complement other existing quality assurance systems by adding external information on the patient and the elements surrounding him or her (people and objects). Such information is today rarely taken into account and may be acquired by means of a global viewing scheme. This system may be used to help minimize errors such as patient's identity, detection of involuntary movements, positioning relatively to a unique referential, presence of treatment accessorizes (bolus, ..) and presence of staff or undesired elements during irradiation, etc.

A new stable phase has been identified in the Nd-Fe-Si system. X-ray diffraction examination of single crystals was used to establish the crystal structure of Nd 6 Fe 13 Si. The tetragonal space group is I 4/ mcm and the lattice parameters are a = b = 0.8034(3)nm, c = 2.278(1)nm. The crystal structure is an ordered version of Nd 6 Ga 3 Fe 11 .Magnetic measurements show an antiferromagnetic behaviour.