High performance underwater UHF radio antenna development

International audienceThis study presents the development of a UHF radioantenna for underwater transmissions in order to rapidly transmit large size files and real-time video

Parallel stepwise stochastic simulation: Harnessing GPUs to Explore Possible Futures States of a Chromosome Folding Model Thanks to the Possible Futures Algorithm (PFA)

International audienceFor the sake of software compatibility, simulations are often parallelized withoutmuch code rewriting. Performances can be further improved by optimizing codes so that to use themaximum power offered by parallel architectures. While this approach can provide some speed-up,performance of parallelized codes can be strongly limited a priori because traditional algorithmshave been designed for sequential technologies. Thus, additional increase of performance shouldultimately rely on some redesign of algorithms.Here, we redesign an algorithm that has traditionally been used to simulate the folding proper-ties of polymers. We address the issue of performance in the context of biological applications,more particularly in the active field of chromosome modelling. Due to the strong confinementof chromosomes in the cells, simulation of their motion is slowed down by the laborious searchfor the next valid states to progress. Our redesign, that we call the Possible Futures Algorithm(PFA), relies on the parallel computation of possible evolutions of the same state, which effectivelyincreases the probability to obtain a valid state at each step. We apply PFA on a GPU-basedarchitecture, allowing us to optimally reduce the latency induced by the computation overhead ofpossible futures. We show that compared to the initial sequential model the acceptance rate of newstates significantly increases without impacting the execution time. In particular, the stronger theconfinement of the chromosome, the more efficient PFA becomes, making our approach appealingfor biological applications.While most of our results were obtained using Fermi architecture GPUs from NVIDIA, we highlightimproved performance on the cutting-edge Kepler architecture K20 GPUs

Radiotherapy modification based on artificial intelligence and radiomics applied to (18F)-fluorodeoxyglucose positron emission tomography/computed tomography.

peer reviewedOver the last decades, the refinement of radiation therapy techniques has been associated with an increasing interest for individualized radiation therapy with the aim of increasing or maintaining tumor control and reducing radiation toxicity. Developments in artificial intelligence (AI), particularly machine learning and deep learning, in imaging sciences, including nuclear medecine, have led to significant enthusiasm for the concept of "rapid learning health system". AI combined with radiomics applied to (18F)-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]-FDG PET/CT) offers a unique opportunity for the development of predictive models that can help stratify each patient's risk and guide treatment decisions for optimal outcomes and quality of life of patients treated with radiation therapy. Here we present an overview of the current contribution of AI and radiomics-based machine learning models applied to (18F)-FDG PET/CT in the management of cancer treated by radiation therapy

The ArT\'eMiS wide-field submillimeter camera: preliminary on-sky performances at 350 microns

ArTeMiS is a wide-field submillimeter camera operating at three wavelengths simultaneously (200, 350 and 450 microns). A preliminary version of the instrument equipped with the 350 microns focal plane, has been successfully installed and tested on APEX telescope in Chile during the 2013 and 2014 austral winters. This instrument is developed by CEA (Saclay and Grenoble, France), IAS (France) and University of Manchester (UK) in collaboration with ESO. We introduce the mechanical and optical design, as well as the cryogenics and electronics of the ArTeMiS camera. ArTeMiS detectors are similar to the ones developed for the Herschel PACS photometer but they are adapted to the high optical load encountered at APEX site. Ultimately, ArTeMiS will contain 4 sub-arrays at 200 microns and 2x8 sub-arrays at 350 and 450 microns. We show preliminary lab measurements like the responsivity of the instrument to hot and cold loads illumination and NEP calculation. Details on the on-sky commissioning runs made in 2013 and 2014 at APEX are shown. We used planets (Mars, Saturn, Uranus) to determine the flat-field and to get the flux calibration. A pointing model was established in the first days of the runs. The average relative pointing accuracy is 3 arcsec. The beam at 350 microns has been estimated to be 8.5 arcsec, which is in good agreement with the beam of the 12 m APEX dish. Several observing modes have been tested, like On-The-Fly for beam-maps or large maps, spirals or raster of spirals for compact sources. With this preliminary version of ArTeMiS, we concluded that the mapping speed is already more than 5 times better than the previous 350 microns instrument at APEX. The median NEFD at 350 microns is 600 mJy.s1/2, with best values at 300 mJy.s1/2. The complete instrument with 5760 pixels and optimized settings will be installed during the first half of 2015.Comment: 11 pages, 11 figures. Presented at SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII, June 24, 2014. To be published in Proceedings of SPIE Volume 915

Identification of CT radiomic features robust to acquisition and segmentation variations for improved prediction of radiotherapy-treated lung cancer patient recurrence.

peer reviewedThe primary objective of the present study was to identify a subset of radiomic features extracted from primary tumor imaged by computed tomography of early-stage non-small cell lung cancer patients, which remain unaffected by variations in segmentation quality and in computed tomography image acquisition protocol. The robustness of these features to segmentation variations was assessed by analyzing the correlation of feature values extracted from lesion volumes delineated by two annotators. The robustness to variations in acquisition protocol was evaluated by examining the correlation of features extracted from high-dose and low-dose computed tomography scans, both of which were acquired for each patient as part of the stereotactic body radiotherapy planning process. Among 106 radiomic features considered, 21 were identified as robust. An analysis including univariate and multivariate assessments was subsequently conducted to estimate the predictive performance of these robust features on the outcome of early-stage non-small cell lung cancer patients treated with stereotactic body radiation therapy. The univariate predictive analysis revealed that robust features demonstrated superior predictive potential compared to non-robust features. The multivariate analysis indicated that linear regression models built with robust features displayed greater generalization capabilities by outperforming other models in predicting the outcomes of an external validation dataset

Influence des systèmes antennaires sur le canal radio numérique : investigations à partir de CAO RF - Séminaire du laboratoire SIC de l'Université de Poitiers

Au regard de la multitude de normes qui leurs sont consacrées, les systèmes de communication sans fils connaissent un essor considérable, notamment depuis lavènement des téléphones cellulaires GSM dans les années 1990, plus récemment avec lusage croissant des ordinateurs portables ou PDA munis de moyens de communications radio, WIFI en particulier. Les habitudes que développent les utilisateurs dans ce contexte, notamment sous linfluence des opérateurs de télécommunication et des fournisseurs de contenus multimédia, induisent des performances sans cesse améliorées pour ces systèmes sans-fils. Cela concerne la richesse des fonctionnalités (télédiffusion haute définition, jeux en réseau), la puissance de traitement embarquée (notamment graphique), lautonomie énergétique, les débits des radio communications, etc... Dans un contexte concurrentiel, les équipementiers doivent maîtriser la production de solutions optimales en terme de rapport performances-coûts, mais soumise aux évolutions rapides des technologies. Cette maîtrise passe ainsi par une modélisation à tous les niveaux, qui diminue considérablement les temps de prototypage, mais dépend de la qualité des modèles et des méthodes de prévision des comportements

Optimization of a Wifi radio antenna for underwater applications

International audienceIn the context of future seabed underwater scientific observatories, a new Wi-Fi antenna (at 2.45 GHz) was recently developed for high data rate and short range wireless underwater applications. It supports real time video and rapid large file transmissions (54 Mb/s during experiments). Also its simplicity and compatibility with standard Wi-Fi equipment (modems, etc.) makes it a low cost solution for underwater applications. Therefore, while first prototypes have ever experimentally demonstrated the capabilities of the developed solution, several optimizations are possible. This paper focuses on size reduction and improvement to sea pressure resistance, bandwidth broadening, and a new antenna excitation which notably enable further height reduction

Méthode semi-analytique de modélisation des couplages inter-antennes pour simulations systèmes

International audienceSi la complexité de lenvironnement de propagation rend difficile de prédiction des distorsions entre les voies des systèmes radio sans fils, la littérature concernant les systèmes MIMO fait aussi état de toute limportance des antennes et des effets des couplages électromagnétiques compte tenu de leurs impacts sur la modification des caractéristiques de rayonnement et les conséquences concernant les corrélations entre voies. Afin de modéliser ces effets de façon rigoureuse pour en tenir compte précisément au sein de simulateurs radio-numériques, une nouvelle méthode qui simplifie lidentification des paramètres circuits du couplage est proposée. Après en avoir exposé le principe, elle est appliquée à lanalyse comparative des coefficients de couplage et de rayonnement modifié pour des antennes filaires monopôle et fractales de type Koch. Les valeurs des coefficients sont reportées en fonction des distances de séparation inter-éléments et en fonction de la fréquence. Les perspectives concernant leffet du couplage inter-antennes vis-à-vis des caractéristiques des sous-canaux MIMO sont présentées, ainsi que lextension de la méthode aux communications ultra larges bandes