The Story of the Dopamine Transporter PET Tracer LBT-999: From Conception to Clinical Use

The membrane dopamine transporter (DAT) is involved in a number of brain disorders and its exploration by positron emission tomography (PET) imaging is highly relevant for the early and differential diagnosis, follow-up and treatment assessment of these diseases. A number of carbon-11 and fluor-18 labeled tracers are to date available for this aim, the majority of them being derived from the chemical structure of cocaine. The development of such a tracer, from its conception to its use, is a long process, the expected result being to obtain the best radiopharmaceutical adapted for clinical protocols. In this context, the cocaine derivative (E)-N-(4-fluorobut-2-enyl)2β-carbomethoxy-3β-(4′-tolyl)nortropane, or LBT-999, has passed all the required stages of the development that makes it now a highly relevant imaging tool, particularly in the context of Parkinson's disease. This review describes the different steps of the development of LBT-999 which initially came from its non-fluorinated derivative (E)-N-(3-iodoprop-2-enyl)-2-carbomethoxy-3-(4-methylphenyl) nortropane, or PE2I, because of its high promising properties. [18F]LBT-999 has been extensively characterized in rodent and non-human primate models, in which it demonstrated its capability to explore in vivo the DAT localized at the dopaminergic nerve endings as well as at the mesencephalic cell bodies, in physiological conditions. In lesion-induced rat models of Parkinson's disease, [18F]LBT-999 was able to precisely quantify in vivo the dopaminergic neuron loss, and to assess the beneficial effects of therapeutic approaches such as pharmacological treatment and cell transplantation. Finally recent clinical data demonstrated the efficiency of [18F]LBT-999 in the diagnosis of Parkinson's disease

Revealing the pace of river landscape evolution during the Quaternary: recent developments in numerical dating methods

During the last twenty years, several technical developments have considerably intensified the use of numerical dating methods for the Quaternary. The study of fluvial archives has greatly benefited from these enhancements, opening new dating horizons for a range of archives at distinct time scales and thereby providing new insights into previously unanswered questions. In this contribution, we separately present the state of the art of five numerical dating methods that are frequently used in the fluvial context: radiocarbon, Luminescence, Electron Spin Resonance (ESR), 230Th/U and terrestrial cosmogenic nuclides (TCN) dating. We focus on the major recent developments for each technique that are most relevant for new dating applications in diverse fluvial environments and on explaining these for non-specialists. Therefore, essential information and precautions about sampling strategies in the field and/or laboratory procedures are provided. For each method, new and important implications for chronological reconstructions of Quaternary fluvial landscapes are discussed and, where necessary, exemplified by key case studies. A clear statement of the current technical limitations of these methods is included and forthcoming developments, which might possibly open new horizons for dating fluvial archives in the near future, are summarised

Procédé et système de conversion analogique/numérique large bande et grande dynamique

La présente invention concerne un procédé de conversion analogique/numérique d'un signal analogique (SA) en un signal numérique (SN) qui est caractérisé en ce qu'il comporte au moins une étape de numérisation intermédiaire et une étape de numérisation finale comportant une sous-étape (SENi) de numérisation des seules composantes fréquentielles d'un signal analogique (SAi), dit signal analogique à traiter à l'étape d'ordre i, ayant des niveaux de puissance qui sont compris entre une valeur supérieure Nimax et une valeur de seuil Si associées à ladite étape de numérisation intermédiaire (ENi), ladite sous-étape (SENi) délivrant un signal numérique (SNi), et une sous-étape (SEEi) d'extraction dudit signal analogique à traiter (SAi) d'ordre i les composantes fréquentielles numérisées pour délivrer ainsi un signal analogique à traiter (SAi+1) pour l'étape de numérisation intermédiaire ou finale (ENi+1) d'ordre suivant, et une étape de combinaison (EC). La présente invention concerne également un système de conversion analogique/numérique pour mettre en œuvre ledit procédé de conversion

Risk assessment of SDR-based attacks with UAVs

International audienceThe use of Unmanned Aerial Vehicles (UAVs) is rising constantly whether for leisure or professional purposes in civilian or Defense domains. We consider in this study small civilian aerial drones of different types, which are low cost, available off the shelf and so affordable for individuals. Simultaneously , they have also raised security concerns for critical sites such as nuclear stations, strategic locations like official buildings, crowded places as stadiums, etc. The aim of this paper is to provide a survey of the risks assessment with and for UAVs in general. Regarding the security concern we pay a specific attention to attacks that are facilitated and can benefit from an easy access to Software Defined Radio (SDR) boards that can be embedded in the UAV or in the ground segment

Wideband Spectrum Sensing Using Modulated Wideband Converter and Data Reduction Invariant Algorithms

International audienceWideband spectrum sensing is a challenging problem in the framework of cognitive radio and spectrum surveillance, mainly because of the high sampling rates required by standard approaches. In this paper, a compressed sensing approach was considered to solve this problem, relying on a sub-Nyquist or Xsampling scheme, known as a modulated wideband converter. First, the data reduction at its output is performed in order to enable a highly effective processing scheme for spectrum reconstruction. The impact of this data transformation on the behavior of the most popular sparse reconstruction algorithms is then analyzed. A new mathematical approach is proposed to demonstrate that greedy reconstruction algorithms, such as Orthogonal Matching Pursuit, are invariant with respect to the proposed data reduction. Relying on the same formalism, a data reduction invariant version of the LASSO (least absolute shrinkage and selection operator) reconstruction algorithm was also introduced. It is finally demonstrated that the proposed algorithm provides good reconstruction results in a wideband spectrum sensing scenario, using both synthetic and measured data

Siamese Network on I/Q Signal for RF Fingerprinting

International audienceRF Fingerprinting techniques aim to authenticate a wireless emitter by the imperfections due to these components. It can be useful for authentication and network management for the future IoT networks. Various methods has been proposed using hand-crafted features and classic machine learning but nowadays many researchers try to apply deep learning architectures for RF Fingeprinting. Our contribution is based on Siamese Network, a deep learning architecture widely used by the face recognition community. We use the deep learning architectures proposed by the RF Fingeprinring community which processes the I/Q (In-phase and Quadrature) signal and the siamese network learning paradigms developed for the facial recognition to propose siamese architectures for RF Fingerprinting. One of the main advantage of the siamese network is the possibility to use one-shot learning and its ability to require a few data for the final implementation of the network. In this paper, we explain our implementation, our results and discuss about the potential benefits of our approach for final implementation in a wireless network

Réseau d’antennes In-Band Full-Duplex Ultra-Large-Bande à double polarisation

National audienceLe réseau d’antennes Ultra-Large-Bande présenté ici est constitué de 4 antennes à double polarisation linéaire alimentées spécifiquement pour créer une structuration symétrique nécessaire à l’obtention d’un fort niveau d’isolation (SIC) en champ proche entre les parties émission et réception. Ce système constitue ainsi l’étage antennaire d’un dispositif « In-Band Full-Duplex » à même d’émettre et de recevoir simultanément sur la même bande de fréquences. Deux autres innovations ont également été développées pour cette application : 2 baluns de 1 vers 4 pour alimenter les parties RX et TX et une nouvelle méthode d’alimentation identique et symétrique pour les deux polarisations. Les simulations du système complet montrent une bonne adaptation de 2 à 20 GHz avec un gain effectif moyen de 11 dBi et une annulation de l’auto-interférence de 120dB en simulation et attendue à 40-50dB en pratique

Ultra‐wideband antenna system for in‐band full‐duplex applications

International audienceIn this paper, we present an ultra-wideband full-duplex antenna system constituted of a wideband 4-element Vivaldi array and wideband microstrip-to-slotline baluns. The proposed system is characterized by its simplicity, high directivity, and high self-interference cancellation levels over a wide frequency bandwidth. The system is abricated using basic PCB technology and can provide at least 50 dB of self-interference cancellation over the bandwidth of operation, 4 - 40 GHz, with an average gain of 7.8 dBi. The system has a size of 8 cm x 8 cm x 9.4 cm and can be used as a high data rate link between two distant wireless nodes. To assess the merits of the proposed system and compare it to other published works, a new figure of merit (FoMWFD) dedicated to wide-band full-duplex antenna topologies is introduced in this paper

Multilayer Miniaturized Wideband Electromagnetic Band-Gaps For Wideband Full-Duplex Transceiver

International audienceThis work introduces a new design approach of multilayer Electromagnetic Band Gaps (EBGs) for wideband antenna isolation in a Full-Duplex transceiver. The design methodology is applied to a conventional type of EBGs in order to improve its initial performance in terms of bandwidth and size. By stacking multiple dielectric layers with integrated vias, an enhancement of the relative bandwidth of the band gap and a strong miniaturization of the unit cell is achieved. The dispersion diagrams of the proposed EBGs are studied and full-wave electromagnetic simulations are realized to validate the isolation level and the proposed lumped model of the final structures

Réseau d'antennes Vivaldi en impression 3D métallisée Ultra-Large-Bande pour applications In-Band Full-duplex

National audienceUn prototype de réseau d'antennes fonctionnant en In-Band Full Duplex (IBFD) ultra-large bande est présentée. Le réseau est formé de quatre antennes Vivaldi réalisées en impression 3D métallisée et alimenté par deux baluns basés sur des transitions microruban-fente. Une attention particulière est portée sur l'effet de l'épaisseur de la fente sur le niveau d'adaptation de la transition. Le réseau mesuré atteint en moyenne 60 dB d'annulation de l'auto-interférence dans la bande de 4,4 GHz à 28,6 GHz et un gain moyen de 9,8 dBi