Système d'alerte dynamique par télédétection pour l'observation des déforestations en Malaisie

La Malaisie est soumise à une forte pression de déforestation. Il est urgent de planifier la culture des palmiers à huile en se tournant vers des stratégies durables. Pour cela, un système d'alerte ciblant les déforestations illégales serait un outil précieux pour les gestionnaires. Google Earth Engine permet de mettre en place un système d'alerte des déforestations à partir d'images satellites à moyenne résolution. Les images optiques Sentinel-2 et Landsat 8 sont associées aux images radars Sentinel-1 pour permettre une revisite régulière et limiter l'impact de la couverture nuageuse. L'analyse par vecteur de changement détecte les déforestations sur chacune des nouvelles acquisitions en fonction d'une donnée de référence forêt.Les résultats montrent une bonne précision avec les capteurs optiques(moins de 11% d'erreur de commission et d'omission). Cependant, le capteur radar donne des résultats plus faibles (14% d'erreur de commission et 28% d'erreur de commission), liés à de nombreux artéfacts causés par l'effet de chatoiement (speckle). C'est pourquoi nous utilisons un score dynamique relatif à l'observation des 3 capteurs sur 3 mois, qui indique un niveau de confiance. Cette méthode permet d'obtenir 7% d'erreur d'omission et 0% d'erreur de commission pour les événements présentant un fort niveau de confiance, caractérisé par un score supérieur à 20 points.Malaysia is under severe deforestation pressure. There is an urgent need to plan oil palm cultivation by turning to sustainable strategies. An alert system targeting illegal deforestation would be a valuable tool for managers. Google Earth Engine is used to set up a warning system of deforestation from medium resolution satellite images. Sentinel-2 and Landsat 8 optical images are combined with Sentinel-1 radar images for high repeatability and limit cloud cover impact. The change vector analysis detects deforestation on each new acquisition based on forest reference image. Results show sufficient accuracy with optical sensors (less than 11% commission and omission error). However, the radar sensor gives lower results (14% commission error and 28% commission error), related to many artefacts caused by the speckle. Therefore, we use a dynamic score related to the observation of 3 sensors over 3 months, which indicates a level of confidence. This method provides 7% of omission error and 0% of commission error for events with a high level of confidence, with a score greater than 20 points

Dynamic Graph: un outil générique pour la modélisation multi-échelle

National audienceModéliser et afficher des scènes animées avec de grandes variations d'échelle est une tache très coûteuse et aujourd'hui impossible à réaliser en temps-réel. Nous montrons que seule la modélisation procédurale multi- échelle est apte à résoudre un tel problème. Une analyse des quelques travaux existants permet d'une part de constater l'efficacité de cette approche, et d'autre part de mettre en évidence l'un de ses plus gros défauts : la quantité de code à écrire pour créer chaque nouveau modèle. C'est là notre principale contribution : nous présentons Dynamic Graph (DG), le premier outil générique pour la modélisation procédurale multi-échelle. Autour d'un noyau basé sur des graphes acycliques dynamiques, de nombreuses fonctionnalités allègent le processus de création sans pour autant nuire à son expressivité

Near real-time deforestation detection in Malaysia and Indonesia using change vector analysis with three sensors

Malaysia and Indonesia have been affected by deforestation caused in great part by the proliferation of oil palm plantations. To survey this loss of forest, several studies have monitored these southeast Asian nations with satellite remote sensing alert systems. The methods used have shown potential for this approach, but they are limited by imagery with coarse spatial resolution, low revisit times, and cloud cover. The objective of this research is to improve near real-time operational deforestation detection by combining three sensors: Sentinel-1, Sentinel-2 and Landsat-8. We used Change Vector Analysis to detect changes between non-affected forest and images under analysis. The results were validated using 166 plots of undisturbed forest and confirmed deforestation events throughout Sabah Malaysian State, and from 70 points from drone pictures in Sumatra, Indonesia. Sentinel-2 and Landsat-8 yielded sufficient results in terms of accuracy (less than 11% of commission and omission error). Sentinel-1 had lower accuracy (14% of commission error and 28% of omission error), probably resulting from geometric distortions and speckle noise. During the high cloud-cover season optical sensors took about twice the time to detect deforestation compared to Sentinel-1 which was not affected by cloud cover. By combining the three sensors, we detected deforestations about 8 days after forest clearing events. Deforestations were only detectable during approximately the first 100 days, before bare soils were often coved by legume crop. Our results indicate that near real-time deforestation detection can reveal most events, but the number of false detections could be improved using a multiple event detection process

Plasticité synaptique corticostriatale à long terme chez de nouveaux modèles murins de Trisomie 21, Ms4Yah et Ts3Yah

Trisomy 21 or Down syndrome is due to a third copy of human chromosome 21 (Hsa21) in the genome, this leads to a global genetic overexpression which results on multiple behavioral phenotypes. This pathology is the first and most common cause of mental retardation. Our study aims to understand whether an aneuploidy of a non-studied genetic interval, included in Hsa21, causes changes in processes mediating intellectual abilities. This interval, between Ctsb and Prmt2, is located on murine chromosome 10 (MMU10) within an homologous portion of the Hsa21 telomeric part. Thus, new mouse models have been engineered, Ms4Yah is monosomic and Ts3Yah trisomic for Cstb-Prmt2 interval. Hence, the aim of this project is to characterized aneuploidy consequences on neuronal functions which lead to information encoding, named long term synaptic plasticity. We have recorded this phenomenon within cortex-striatum neuronal connexion, which is involved in mnemonic processes, using whole-cell patch-clamp electrophysiological technique. Records were made in vitro on mouse horizontal brain slice. We characterized METMs electrophysiological properties. Then, glutamatergic corticostriatal long term synaptic plasticity was studied with specific stimulation protocols applied on the cortex. High and low frequency conditioning protocols were used. We observed that aneuploidy of the models influenced corticostriatal long term synaptic plasticity setting which is different according to the genetic dosage. Ms4Yah showed LTD after HFS protocol like Ts3Yah. But when SBF was applied, Ms4Yah shows a short term plasticity form, conversely Ts3Yah shows anew a LTD. The studied interval may play here a role in phenotype of Trisomy 21. Some of the genes comprised in the Ctsb-Prmt2 interval seemed to be good candidates to explain observed phenotypes, namely S100b, Pcbp3 and Trmp2.La Trisomie 21 ou Syndrome de Down, est due à la présence surnuméraire du chromosome 21 humain (Hsa21), le surdosage génétique qui en résulte provoque différents phénotypes. Cette pathologie est la première cause de retard mental. Notre étude vise à savoir si l’aneuploïdie d’un intervalle génétique, encore non étudié, entraîne des modifications dans la mise en place des processus à l’origine des facultés cognitives. Cet intervalle, entre les gènes Cstb et Prmt2 est porté par le chromosome murin 10 (MMU10) au sein d’une portion homologue à la partie télomérique du Hsa21. Pour cela de nouveaux modèles murins ont été créés, Ms4Yah est monosomique et Ts3Yah est trisomique pour cet intervalle. Le but est donc de caractériser les conséquences de l’aneuploïdie sur le fonctionnement des neurones permettant l’encodage des informations, appelé plasticité synaptique à long terme. Nous avons enregistré ce phénomène au niveau de la communication entre le cortex et le striatum, structures impliquées dans les processus mnémoniques, grâce à la technique électrophysiologique de patch clamp en configuration cellule entière. Ces enregistrements sont faits in vitro sur tranches de cerveaux de souris. Les propriétés électrophysiologiques des NETMs ont été caractérisées. La plasticité synaptique corticostriatale à long terme de type glutamatergique a été étudiée avec des protocoles de stimulation spécifiques, appliqués au niveau cortical. Des protocoles de conditionnement à haute et à basse fréquence ont été utilisés. Nous avons observé que l’aneuploïdie portée par les modèles avait une influence sur la mise en place de la plasticité synaptique corticostriatale à long terme qui est différente en fonction du dosage génétique. Ms4Yah met en place une DLT suite au protocole SHF de même que Ts3Yah. Lorsque le protocole SBF est utilisé Ms4Yah met en place une forme de plasticité à court terme contrairement à Ts3Yah qui présente une DLT. L’intervalle étudié ici jouerait donc un rôle dans le phénotype de la Trisomie 21. Certains gènes de l’intervalle semblent être de bons candidats pour expliquer les phénomènes observés, notamment S100b, Pcbp3 et Trmp2

Plasma thioredoxin levels during post-cardiac arrest syndrome: relationship with severity and outcome

International audienceIntroductionDespite experimental evidence, clinical demonstration of acute state of oxidative stress and inflammation during post-cardiac arrest syndrome is lacking. Plasma level of thioredoxin (TRX), a redox-active protein induced under conditions of oxidative stress and inflammation, is increased in various critical care conditions. We determined plasma TRX concentrations after cardiac arrest and assessed relationships with severity and outcome.MethodsRetrospective study of consecutive patients admitted to a single academic intensive care unit (ICU) for out-of-hospital cardiac arrest (between July 2006 and March 2008). Plasma levels of TRX were measured at admission, day (D) 1, 2 and 3.ResultsOf 176 patients included, median TRX values measured in ICU survivors and non-survivors were, respectively: 22 ng/mL (7.8 to 77) vs. 72.4 (21.9 to 117.9) at admission (P TRX levels on admission were significantly correlated with 'low-flow' duration (P = 0.003), sequential organ failure assessment (SOFA) score (P ConclusionsOur data show for the first time that TRX levels were elevated early following cardiac arrest, suggestive of oxidative stress and inflammation occurring with this condition. Highest values were found in the most severe patients. TRX could be a useful tool for further exploration and comprehension of post-cardiac arrest syndrome

Evaluation of hip fracture risk using a hyper-parametric model based on the Locally Linear Embedding technique

The authors wish to thank the Spanish "Ministerio de Economia y Competitividad", the "Generalitat Valenciana" and the "Ministerio de Educacion" for their financial support received through the projects DPI2017-89816-R, Prometeo 2016/007 and FPU016/07122, respectively.Nadal, E.; Muñoz-Pellicer, D.; Nivó, N.; Lucas, I.; Ródenas, JJ. (2019). Evaluation of hip fracture risk using a hyper-parametric model based on the Locally Linear Embedding technique. Comptes Rendus Mécanique. 347(11):856-862. https://doi.org/10.1016/j.crme.2019.11.010S8568623471

A recruitment maneuver increases oxygenation after intubation of hypoxemic intensive care unit patients: a randomized controlled study

International audienc

Tau Oligomer–Containing Synapse Elimination by Microglia and Astrocytes in Alzheimer Disease

Importance: Factors associated with synapse loss beyond amyloid-β plaques and neurofibrillary tangles may more closely correlate with the emergence of cognitive deficits in Alzheimer disease (AD) and be relevant for early therapeutic intervention. // Objective: To investigate whether accumulation of tau oligomers in synapses is associated with excessive synapse elimination by microglia or astrocytes and with cognitive outcomes (dementia vs no dementia [hereinafter termed resilient]) of individuals with equal burdens of AD neuropathologic changes at autopsy. // Design, Setting, and Participants: This cross-sectional postmortem study included 40 human brains from the Massachusetts Alzheimer Disease Research Center Brain Bank with Braak III to IV stages of tau pathology but divergent antemortem cognition (dementia vs resilient) and cognitively normal controls with negligible AD neuropathologic changes. The visual cortex, a region without tau tangle deposition at Braak III to IV stages, was assessed after expansion microscopy to analyze spatial relationships of synapses with microglia and astrocytes. Participants were matched for age, sex, and apolipoprotein E status. Evidence of Lewy bodies, TDP-43 aggregates, or other lesions different from AD neuropathology were exclusion criteria. Tissue was collected from July 1998 to November 2020, and analyses were conducted from February 1, 2022, through May 31, 2023. // Main Outcomes and Measures: Amyloid-β plaques, tau neuropil thread burden, synapse density, tau oligomers in synapses, and internalization of tau oligomer–tagged synapses by microglia and astrocytes were quantitated. Analyses were performed using 1-way analysis of variance for parametric variables and the Kruskal-Wallis test for nonparametric variables; between-group differences were evaluated with Holm-Šídák tests. // Results: Of 40 included participants (mean [SD] age at death, 88 [8] years; 21 [52%] male), 19 had early-stage dementia with Braak stages III to IV, 13 had resilient brains with similar Braak stages III to IV, and 8 had no dementia (Braak stages 0-II). Brains with dementia but not resilient brains had substantial loss of presynaptic (43%), postsynaptic (33%), and colocalized mature synaptic elements (38%) compared with controls and significantly higher percentages of mature synapses internalized by IBA1-positive microglia (mean [SD], 13.3% [3.9%] in dementia vs 2.6% [1.9%] in resilient vs 0.9% [0.5%] in control; P < .001) and by GFAP-positive astrocytes (mean [SD], 17.2% [10.9%] in dementia vs 3.7% [4.0%] in resilient vs 2.7% [1.8%] in control; P = .001). In brains with dementia but not in resilient brains, tau oligomers more often colocalized with synapses, and the proportions of tau oligomer–containing synapses inside microglia (mean [SD] for presynapses, mean [SD], 7.4% [1.8%] in dementia vs 5.1% [1.9%] resilient vs 3.7% [0.8%] control; P = .006; and for postsynapses 11.6% [3.6%] dementia vs 6.8% [1.3%] resilient vs 7.4% [2.5%] control; P = .001) and astrocytes (mean [SD] for presynapses, 7.0% [2.1%] dementia vs 4.3% [2.2%] resilient vs 4.0% [0.7%] control; P = .001; and for postsynapses, 7.9% [2.2%] dementia vs 5.3% [1.8%] resilient vs 3.0% [1.5%] control; P < .001) were significantly increased compared with controls. Those changes in brains with dementia occurred in the absence of tau tangle deposition in visual cortex. // Conclusion and Relevance: The findings from this cross-sectional study suggest that microglia and astrocytes may excessively engulf synapses in brains of individuals with dementia and that the abnormal presence of tau oligomers in synapses may serve as signals for increased glial-mediated synapse elimination and early loss of brain function in AD

Circulating adrenomedullin estimates survival and reversibility of organ failure in sepsis: the prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock-1 (AdrenOSS-1) study

Background: Adrenomedullin (ADM) regulates vascular tone and endothelial permeability during sepsis. Levels of circulating biologically active ADM (bio-ADM) show an inverse relationship with blood pressure and a direct relationship with vasopressor requirement. In the present prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock 1 (, AdrenOSS-1) study, we assessed relationships between circulating bio-ADM during the initial intensive care unit (ICU) stay and short-term outcome in order to eventually design a biomarker-guided randomized controlled trial. Methods: AdrenOSS-1 was a prospective observational multinational study. The primary outcome was 28-day mortality. Secondary outcomes included organ failure as defined by Sequential Organ Failure Assessment (SOFA) score, organ support with focus on vasopressor/inotropic use, and need for renal replacement therapy. AdrenOSS-1 included 583 patients admitted to the ICU with sepsis or septic shock. Results: Circulating bio-ADM levels were measured upon admission and at day 2. Median bio-ADM concentration upon admission was 80.5 pg/ml [IQR 41.5-148.1 pg/ml]. Initial SOFA score was 7 [IQR 5-10], and 28-day mortality was 22%. We found marked associations between bio-ADM upon admission and 28-day mortality (unadjusted standardized HR 2.3 [CI 1.9-2.9]; adjusted HR 1.6 [CI 1.1-2.5]) and between bio-ADM levels and SOFA score (p &lt; 0.0001). Need of vasopressor/inotrope, renal replacement therapy, and positive fluid balance were more prevalent in patients with a bio-ADM &gt; 70 pg/ml upon admission than in those with bio-ADM ≤ 70 pg/ml. In patients with bio-ADM &gt; 70 pg/ml upon admission, decrease in bio-ADM below 70 pg/ml at day 2 was associated with recovery of organ function at day 7 and better 28-day outcome (9.5% mortality). By contrast, persistently elevated bio-ADM at day 2 was associated with prolonged organ dysfunction and high 28-day mortality (38.1% mortality, HR 4.9, 95% CI 2.5-9.8). Conclusions: AdrenOSS-1 shows that early levels and rapid changes in bio-ADM estimate short-term outcome in sepsis and septic shock. These data are the backbone of the design of the biomarker-guided AdrenOSS-2 trial. Trial registration: ClinicalTrials.gov, NCT02393781. Registered on March 19, 2015