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International audience; A long-range transmission demonstrator for low data rate environmental sensor networks is under development. It uses the ISM free-access frequency band at 433 MHz. In addition to distance attenuation, a major issue is the presence of numerous radio frequency interferences in this band. With a view to optimizing the sensor life and cost, the system complexity has been shifted to the central station which will be based on array processing techniques. In this paper, we describe a spatial cyclostationary detector for triggering the acquisition of sensor data frames in this highly corruptive radio environment.

4 pages; International audience; In [1], the authors have approached the sphere-like surfaces using the tensor product of an algebraic cubic spline quasiinterpolant with a 2¼-periodic Uniform Algebraic Trigonometric B-splines (UAT B-splines) of order four. In this paper, we improve the results given in [1], by introducing a new quasi-interpolant based on the tensor product of an algebraic cubic spline quasi-interpolant with a periodic cubic spline quasi-interpolant, obtained by the periodization of an algebraic cubic spline quasi-interpolant. Our approach allows us to obtain an approximating surface which is of class C2 and with an approximation order O(h4). We show that this method is particularly well designed to render 3D closed surfaces, and it has been successfully applied to reconstruct human organs such as the left ventricle of the heart.

International audience; In the transgenic research era, the understanding of the functional consequences of the genes deletions or mutations in order to investigate the origin of human transgenic disease, requires the development of non invasive study methods on murine models. Our aim is to develop new Down syndrome models and a 3D reconstruction software using MEMRI at 9.4T. To improve contrast and spatial resolution at high magnetic field, the Mn2+ contrast agent shows powerful paramagnetic properties leading to a significant increase of MRI signal [1]. Mn2+ is a unique marker for neuroarchitecture, neuronal connections and functions therefore particularly interesting for neuropathological studies in vivo. In order to investigate the morphological and structural consequences on the central nervous system development in new mice models of human chromosome 21 aneuploïdies, we used MEMRI and. we also developed a powerful tool in order to perform an automatic segmentation and 3D reconstruction of three brain structures.

International audience; In this paper, we propose a modified variational splines fitting (MVSF) algorithm for the reconstruction and comparison of medical surfaces. The MVSF algorithm presents the advantage to use high precise and low complex approximation of the equations of energy in the discrete temporal domain, compared to previously presented methods. It also takes into account the periodicity constraints encountered when reconstructing sphere-like shape closed surfaces. Moreover, it gives straightly the mean square error (MSE) between the original data and the reconstructed data, which is useful to quantify the approximation introduced by the reconstruction. The developed model has been successfully applied for real biomedical data; in particular for the reconstruction and comparison of the left ventricle of human heart, acquired by SPECT and ultrasound imaging modalities.

International audience; In digital image processing, skeletonization is a valuable technique for the characterization of complex 3D porous media, such as bone, stone and soils. 3D thinning algorithms are usually used to extract one-voxel wide skeleton from 3D porous objects while preserving the topological information. Models based on simplified skeletons have been shown to be efficient in retrieving morphological information from large scale disordered objects at a local level. In this paper, we present a series of 3D skeleton-based image processing techniques for evaluating the micro-architecture of large scale disordered porous media. The proposed hybrid skeleton method combines curve and surface thinning methods with the help of an enhanced shape classification algorithm. Results on two different porous objects demonstrate the ability of the hybrid skeleton method to provide significant topological and morphological information.

International audience; In this paper, a semi automatic active contour method based on Chan-Vese model is proposed for the segmentation of mouse brain MR images. First, a 2 ½ D strategy is applied on the axial images to segment the 3D volume of interest. The method takes into account the special shape of the object to segment. Moreover, the user defines the limits where to search these contours and also provides an initial contour. This semi automatic method makes that human intervention is limited and the tedious manual handling is greatly reduced. Results have shown that the brain volumes estimated by the method are identical to expert manually estimated volumes. Last but not least, the new method was used in the analysis of the cerebral malformations linked to Trisomy 21: no significant difference of the brain volumes between Tri-somy 21 mice and the control ones were found.

International audience; The segmentation of different cerebral structures of mice is becoming more and more important due to the growing interest in finding small animal models of human diseases. In this work, variational atlases are constructed by manual segmentation of various MRI brain images of reference and trisomy 21 mice. These atlases are then registered to assist the segmentation of fine cerebral structures such as the cerebellum and the hippocampus. A modified Chan-Vese segmentation method is used for the detection of these structures. Global as well as local comparison of the reconstructed surfaces and volumes are hence conducted to better understand the gene involved in the morphological malformations associated to trisomy.

International audience; This paper presents a Modified Variational Splines Fitting (MVSF) algorithm for surface reconstruction using thin plate splines on scattered patches or points of originally smooth surfaces. In particular, a more accurate derivation of the discrete equations for the energy corresponding to the thin plate model is introduced. The results obtained on simulated data show that the proposed algorithm converges faster than the original VSF algorithm. Additionally, we discuss an approach for choosing the algorithm's parameters using a cross validation technique. Results obtained with the modified algorithm are compared to those using a Frequency Fourier-based 3D Harmonic modelling (3DHM) algorithm and show that the proposed algorithm gives an improved performance under the small sample size condition. The developed model has been successfully applied for real biomedical data; in particular for the reconstruction of left ventricle of human heart.

International audience; Image registration is a valuable technique for medical diagnosis and treatment. In this paper, we present an enhanced implementation of the popular iterative closest point (ICP) algorithm developed for the registration of 3D free-form closed surfaces, based on the use of a look up matrix for finding the best correspondence pairs. The algorithm, called Comprehensive ICP (CICP) algorithm, is then successfully applied for comparing two sequences of 3D surfaces of the left ventricle of the heart, obtained from two different modalities: 4D Echography and Gated SPECT. The results show a good correspondence between the reconstructed sequence from 4D Echography and the reference Gated SPECT sequence. This study can be extended to comparing different medical reconstructions of sphere-like shaped organs collected from different modalities.

International audience; Facing the disaffection of students for electronic engineering studies, we decided to have global brainstorming with students and then with teachers and enterprises to define new engineering courses that could be attractive and useful. The paper describes the problematic addressed, the way we used to build this curriculum and the new course as proposed to the students. We also emphasize all along the text on the problems we had to solve till the attribution of the accreditation.