Ecoute Coopérative de Spectre pour la Radio Cognitive

National audienceDans cet article, nous proposons une méthode d'écoute coopérative du spectre dans le but de détecter la présence de bandes de fréquences inoccupées. La méthode en question est autodidacte en ce sens qu'aucune information sur le signal émis n'est requis. Nous analysons les performances du test proposé en termes de probabilité de fausse alarme et de puissance. L'analyse théorique des performances repose sur la théorie des matrices aléatoires appliquée aux modèles dits “spiked”

Ecoute Coopérative de Spectre pour la Radio Cognitive

In this paper, we propose a cooperative sensing method which allows to determine the unoccupied bands of the spectrum of wireless communication systems. Our approach is blind i.e., it does not require any cooperation between the transmitters and the sensors. We study the performance of the test in terms of probability of false alarm and miss probability. The theoretical analysis is based on results of Random Matrix Theory for spiked models

Pedicel anatomy and histology in tomato vary according to genotype and water-deficit environment, affecting fruit mass

International audienceThe growth and composition of fleshy fruits depend on resource acquisition and distribution in the plant. In tomato, the pedicel serves as the final connection between plant and fruit. However, very few quantitative data are available for the conducting tissues of the pedicel, nor is their genetic variability known. In the present study, a histological approach was combined with process-based modeling to evaluate the potential contribution made by the anatomy and histology of the pedicel to variations in fruit mass. Eleven genotypes were characterized and the impact of water deficit was studied for a single genotype using stress intensity and stage of application as variables. The results highlighted extensive variations in the relative proportions of the different pedicel tissues and in the absolute areas of xylem and phloem between genotypes. The model suggests that the variations in the area of the pedicel's vascular tissues induced by differences in genotype and water-deficit environments partly contributed to fruit mass variability. They therefore warrant phenotyping for use in the development of plant strains adapted to future environmental constraints. The results also demonstrated the need to develop non-invasive in vivo measurement methods to establish the number and size of active vessels and the flow rates in these vessels to improve prediction of water fluxes in plant architecture

Structural and functional contributions of conducting tissues to genotypic and environmental variations of tomato fruit mass

International audienceConductive tissues are main routes of resource transport, that are crucial for the growth of fleshy fruit. Yet, very few quantitative data of xylem and phloem areas are available and their variabilities are unknown. This study aimed at better understanding and quantifying the structural and functional properties of the conductive tissues in tomato pedicel. 11 contrasting genotypes were described and the impact of water deficit was studied depending on stress intensity and stage of application. In parallel, MRI was used to assess the proportion and size of active xylem vessels in the stem. Results were implemented in a Virtual Fruit model to assess the potential contribution of pedicel conductive tissues in the variability of fruit fresh and dry masses. On their whole, results suggested that variations in the properties of conducting tissues are involved in the genotypic and environmental variations of fruit mass. The study also highlights the interest to combine methods and to integrate knowledge to better understand plant functioning, and finally to improve plant models. Flow-MRI was shown to be an easy non-destructive method to measure the functional properties of conducting tissues such as the proportion of active vessels and their diameter

Inhibiting microglia proliferation after spinal cord injury improves recovery in mice and nonhuman primates

Abstract No curative treatment is available for any deficits induced by spinal cord injury (SCI). Following injury, microglia undergo highly diverse activation processes, including proliferation, and play a critical role on functional recovery. In a translational objective, we investigated whether a transient pharmacological reduction of microglia proliferation after injury is beneficial for functional recovery after SCI in mice and nonhuman primates. The colony stimulating factor-1 receptor (CSF1R) regulates proliferation, differentiation, and survival of microglia, we thus used an oral administration of GW2580, a CSF1R inhibitor. First, transient post-injury GW2580 administration in mice improves motor function recovery, promotes tissues preservation and/or reorganization (identified by coherent anti-stokes Raman scattering microscopy), and modulates glial reactivity. Second, post-injury GW2580-treatment in nonhuman primates reduces microglia proliferation, improves functional motor function recovery, and promotes tissue protection. Notably, three months after lesion microglia reactivity returned to baseline value. Finally, to initiate the investigation on molecular mechanisms induced by a transient post-SCI GW2580-treatment, we used microglia-specific transcriptomic analysis in mice. Notably, we detected a downregulation in the expression of inflammatory-associated genes and we identified genes that were up-regulated by SCI and further downregulated by the treatment. Thus, a transient oral GW2580 treatment post-injury may provide a promising therapeutic strategy for SCI patients and may also be extended to other central nervous system disorders displaying microglia activation

End-to-end multimodal 3D imaging and machine learning workflow for non-destructive phenotyping of grapevine trunk internal structure

Abstract Quantifying healthy and degraded inner tissues in plants is of great interest in agronomy, for example, to assess plant health and quality and monitor physiological traits or diseases. However, detecting functional and degraded plant tissues in-vivo without harming the plant is extremely challenging. New solutions are needed in ligneous and perennial species, for which the sustainability of plantations is crucial. To tackle this challenge, we developed a novel approach based on multimodal 3D imaging and artificial intelligence-based image processing that allowed a non-destructive diagnosis of inner tissues in living plants. The method was successfully applied to the grapevine (Vitis vinifera L.). Vineyard’s sustainability is threatened by trunk diseases, while the sanitary status of vines cannot be ascertained without injuring the plants. By combining MRI and X-ray CT 3D imaging with an automatic voxel classification, we could discriminate intact, degraded, and white rot tissues with a mean global accuracy of over 91%. Each imaging modality contribution to tissue detection was evaluated, and we identified quantitative structural and physiological markers characterizing wood degradation steps. The combined study of inner tissue distribution versus external foliar symptom history demonstrated that white rot and intact tissue contents are key-measurements in evaluating vines’ sanitary status. We finally proposed a model for an accurate trunk disease diagnosis in grapevine. This work opens new routes for precision agriculture and in-situ monitoring of tissue quality and plant health across plant species

Micro‐CT and high‐field MRI for studying very early post‐mortem human fetal anatomy at 8 weeks of gestation

International audienceObjective This study involved very early post‐mortem (PM) examination of human fetal anatomy at 8 weeks of gestation (WG) using whole‐body multimodal micro‐imaging: micro‐CT and high‐field MRI (HF‐MRI). We discuss the potential place of this imaging in early first‐trimester virtual autopsy. Methods We performed micro‐CT after different contrast‐bath protocols including diffusible iodine‐based contrast‐enhanced (dice) and HF‐MRI with a 9.4 T machine with qualitative and quantitative evaluation and obtained histological sections. Results Nine fetuses were included: the crown–rump length was 10–24 mm and corresponded to 7 and 9 WG according to the Robinson formula. The Carnegie stages were 17–21. Dice micro‐CT and HF‐MRI presented high signal to noise ratio, >5, according to the Rose criterion, and for allowed anatomical phenotyping in these specimens. Imaging did not alter the histology, allowing immunostaining and pathological examination. Conclusion PM non‐destructive whole‐body multimodal micro‐imaging: dice micro‐CT and HF‐MRI allows for PM human fetal anatomy study as early as 8 WG. It paves the way to virtual autopsy in the very early first trimester. Obtaining a precision phenotype, even regarding miscarriage products, allows a reverse phenotyping to select variants of interest in genome‐wide analysis, offering potential genetic counseling for bereaved parents

Inhibiting microglia proliferation after spinal cord injury improves recovery in mice and nonhuman primates

International audienceNo curative treatment is available for any deficits induced by spinal cord injury (SCI). Following injury, microglia undergo highly diverse activation processes, including proliferation, and play a critical role on functional recovery. In a translational objective, we investigated whether a transient pharmacological reduction of microglia proliferation after injury is beneficial for functional recovery after SCI in mice and nonhuman primates. Methods: The colony stimulating factor-1 receptor (CSF1R) regulates proliferation, differentiation, and survival of microglia. We orally administrated GW2580, a CSF1R inhibitor that inhibits microglia proliferation. In mice and nonhuman primates, we then analyzed treatment outcomes on locomotor function and spinal cord pathology. Finally, we used cell-specific transcriptomic analysis to uncover GW2580-induced molecular changes in microglia. Results: First, transient post-injury GW2580 administration in mice improves motor function recovery, promotes tissue preservation and/or reorganization (identified by coherent anti-stokes Raman scattering microscopy), and modulates glial reactivity. Second, post-injury GW2580-treatment in nonhuman primates reduces microglia proliferation, improves motor function recovery, and promotes tissue protection. Finally, GW2580-treatment in mice induced down-regulation of proliferation-associated transcripts and inflammatory associated genes in microglia that may account for reduced neuroinflammation and improved functional recovery following SCI. Conclusion: Thus, a transient oral GW2580 treatment post-injury may provide a promising therapeutic strategy for SCI patients and may also be extended to other central nervous system disorders displaying microglia activation