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Conception de systèmes IoT autonomes : apport des technologies RF
No full textIn the context of the strong miniaturization of embedded systems and the massive deployment of the Internet of Things (IoT), the autonomous powering of sensors represents a major technological challenge. This thesis focuses on ambient energy harvesting, particularly the exploitation of radio frequency (RF) waves, which are ubiquitous in urban environments, as a power source for battery-free devices. The work explores the design of Schottky diode rectifiers optimized by the introduction of a resistance compression network to improve their efficiency and stability. It also proposes flexible, dualband, biocompatible antennas, which are effective even when in contact with the human body. Finally, an experimental demonstration implements a very low-power RFID system, achieving a range of 90 meters, surpassing the performance of current commercial devices. All these contributions pave the way for more sustainable, compact, and environmentally integrated battery-free IoT sensors.Dans un contexte de forte miniaturisation des systèmes embarqués et de déploiement massif de l’Internet des Objets (IoT), l’alimentation autonome des capteurs constitue un défi technologique majeur. Cette thèse s’intéresse à la récupération d’énergie ambiante, et plus particulièrement à l’exploitation des ondes radiofréquences (RF), omniprésentes en environnement urbain, comme source d’alimentation pour des dispositifs sans pile. Le travail mené explore la conception de circuits redresseurs à diodes Schottky optimisés par l’introduction d’un réseau de compression de résistances, afin d’améliorer leur rendement et leur stabilité. Il propose également des antennes bibandes flexibles en matériau biocompatible, efficaces même au contact du corps humain. Enfin, une démonstration expérimentale met en oeuvre un système RFID ultra basse consommation, atteignant une portée de 90 mètres, surpassant les performances des dispositifs commerciaux actuels. L’ensemble de ces contributions ouvre la voie à des capteurs IoT sans pile, plus durables, compacts et intégrés à leur environnement
Entre engagement militant et stratégie de distinction marchande. La participation des chef-fes d’entreprise dans la monnaie locale eusko au Pays basque
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West Nile and Usutu Viruses: Introduction and Dynamics of Two Emerging Orthoflaviviruses in France
No full textInternational audienceIntroduction: West Nile virus (WNV) and Usutu virus (USUV) are neurotropic and zoonotic arboviruses of the Orthoflavivirus genus (Flaviviridae family), both maintained in an enzootic cycle involving ornithophilic Culex mosquitoes and avian reservoir hosts. Originating from Africa, where they were first described at the beginning of the twenty century, WNV spreads globally (nine lineages) while USUV emerged only in Europe (eight lineages). WNV strains belonging to lineages 1 and 2 are considered the most important causative agent of viral encephalitis in human and horses, and WNV infection is a notifiable disease at the EU level in humans, equids and avifauna. Almost all USUV lineages have been described in Europe and are responsible for major epizooties in wild and/or captive birds. In France, WNV and USUV are considered as emerging pathogens due to the extension of their geographical distribution and an increase frequency of the outbreaks.Methods: The European and French National Reference laboratory is involved in a multidisciplinary One Health surveillance system for WNV and USUV with partners from the medical, veterinary and entomological sectors. In addition to the diagnostic activity of clinically symptomatic horses or captive birds (serological and molecular tools), whole genome sequencing of the circulating strain integrated the surveillance workflow to better understand viral emergence and dynamics.Results: Here, we will present the emergence and contrasted dynamics of WNV strains belonging to lineage 2 in southern France since 2018. Additionally, we will discuss the molecular epidemiology of avian USUV infections in France since its introduction in 2015.Discussion: The intensification of WNV and USUV circulation in France underline the need to extend and reinforce the surveillance system over the whole territory. Alerting the authorities at an early stage would enable public decision-makers to better prevent and control virus spread and limit public health consequences
Terahertz Synthetic Aperture-based Spatiotemporal Imaging
No full textInternational audienceTerahertz (THz) microscopy has garnered significant attention due to the unique properties of THz radiation, making it appealing for chemical sensing, biomedical diagnostics, and imaging of complex media applications. However, conventional THz imaging systems encounter fundamental resolution limitations due to the Rayleigh diffraction limit. To overcome this challenge, we propose an innovative theoretical and numerical framework by adopting Fourier synthetic aperture principles in the THz spectral range. Our approach synthesizes high spatial frequency components by illuminating the sample with broadband THz pulses from multiple angles and capturing the time-resolved scattered fields through state-of-the-art timedomain spectroscopy (TDS). Our method offers a field-sensitive and experimentally viable solution for surpassing the diffraction limit in THz imaging. It paves the way for high-resolution, labelfree material characterization and noninvasive imaging across various domains, including materials science, biomedical imaging, and security screening.</div
Identification of INOSITOL PHOSPHORYLCERAMIDE SYNTHASE 2 ( IPCS2 ) as a new rate‐limiting component in Arabidopsis pathogen entry control
No full textInternational audienceINOSITOL PHOSPHORYLCERAMIDE SYNTHASE 2 (IPCS2) is involved in the biosynthesis of complex sphingolipids at the trans ‐Golgi network (TGN). Here, we demonstrate a role of IPCS2 in penetration resistance against non‐adapted powdery mildew fungi. A novel ipcs2 W205 * mutant was recovered from a forward genetic screen for Arabidopsis plants with enhanced epidermal cell entry success of the non‐adapted barley fungus Blumeria graminis f. sp. hordei ( Bgh ). A yeast complementation assay and a sphingolipidomic approach revealed that the ipcs2 W205 * mutant represents a knock‐out and lacks IPCS2‐specific enzymatic activity. Further mutant analyses suggested that IPCS2‐derived glycosyl inositol phosphorylceramides (GIPCs) are required for cell entry control of non‐adapted fungal intruders. Confocal laser scanning microscopy (CLSM) studies indicated that upon pathogen attack, IPCS2 remains at the TGN to produce GIPCs, while focal accumulation of the defense cargo PENETRATION 3 (PEN3) at Bgh penetration sites was reduced in the ipcs2 W205 * mutant background. Thus, we propose a model in which sorting events at the TGN are facilitated by complex sphingolipids, regulating polar secretion of PEN3 to host‐pathogen contact sites to terminate fungal ingress
NEWGAIN project at GANIL: construction of the new heavy ion injector for SPIRAL2
No full textInternational audienceA new project, NEWGAIN (NEW GAnil Injector), is under construction at GANIL, and aims to build a second injector for heavier beams with A/q up to 7, as an extension of the SPIRAL2 accelerator. With this upgrade, SPIRAL2 will provide high intensity beams, from proton to uranium, thus increasing GANIL international competitiveness both in fundamental science and associated applications.The presentation will provide an update on the progress of the construction phase and the main milestones achieved and to come. The layout and the main technical components of the new injector, based on 2 ECR ion sources (one of them existing), two LEBT, one RFQ and a MEBT section to transport the beam into the present MEBT connected to the LINAC will be presented
Reconstructing the palaeoclimate of the Cradle of Humankind in South Africa over the last 3.5 million years using machine learning and mammalian fossil assemblages
No full textInternational audienceHypotheses linking climate change to hominin evolution are based on the observation that many events of speciation, extinction, and morphological and behavioural evolution coincided with periods of increased climatic variability and habitat instability. Fossil fauna recovered from palaeoanthropological sites can be used to reconstruct past climatic and environmental conditions associated with hominin assemblages and to explore correlative changes through time. However, temporal correlations between global climate change patterns and local environmental proxies from hominin-bearing deposits are not always verifiable. This study explores the use of machine learning algorithms for faunal-based palaeoenvironmental reconstructions in the Cradle of Humankind (CoH) over the past 3.5 million years. We develop a new method based on random forest models using the presence/absence data of rodents and bovids, two clades commonly employed in palaeoenvironmental reconstructions, to assess the evolution of six temperature and precipitation variables in the region. In contrast to continental-scale trends, we found no evidence for a gradual transition toward more arid conditions. Instead, all reconstructions indicate lower precipitation levels accompanied by more moderate interannual precipitation variability in the past. Although interpretations differ slightly when faunal indicators are analysed separately, the combined evidence from rodents and bovids shows that habitats, despite considerable climatic variability through time, consistently occupied the ecotone between grassland and savanna, closely resembling present-day conditions in the CoH. These findings challenge hypotheses that propose a progressive shift from closed, mesic environments to open, arid landscapes during the Pliocene and Pleistocene in the region
Silhouettes and generic properties of subgroups of the modular group
No full textInternational audienceWe show that the probability for a finitely generated subgroup of the modular group, of size n , to be almost malnormal or non-parabolic, tends to 0 as n tends to infinity – where the notion of the size of a subgroup is based on a natural graph-theoretic representation of the subgroup. The proofs of these results rely on the combinatorial and asymptotic study of a natural map, which associates with any finitely generated subgroup of \mathsf{PSL}_{2}(\mathbb{Z}) a graph which we call its silhouette, which can be interpreted as a conjugacy class of free finite index subgroups of \mathsf{PSL}_{2}(\mathbb{Z})
