Hierarchical Beamforming: Resource Allocation, Fairness and Flow Level Performance

We consider hierarchical beamforming in wireless networks. For a given population of flows, we propose computationally efficient algorithms for fair rate allocation including proportional fairness and max-min fairness. We next propose closed-form formulas for flow level performance, for both elastic (with either proportional fairness and max-min fairness) and streaming traffic. We further assess the performance of hierarchical beamforming using numerical experiments. Since the proposed solutions have low complexity compared to conventional beamforming, our work suggests that hierarchical beamforming is a promising candidate for the implementation of beamforming in future cellular networks.Comment: 34 page

Analyse comparée des écosystèmes digestifs du rumen de la vache et du caecum du lapin

Dans cette revue nous avons synthétisé les données obtenues dans notre équipe et celles de la bibliographie afin de contribuer à une meilleure connaissance de l’écologie des communautés bactériennes et archées des fermenteurs digestifs des mammifères herbivores. L’analyse a porté sur la comparaison des deux principales stratégies digestives rencontrées chez les mammifères herbivores actuels : un fermenteur en position proximale, le rumen, et un fermenteur en position distale, le caecum. Parmi les espèces d’intérêt agronomique,la vache et le lapin on été choisis comme animaux modèles. Après avoir rappelé les caractéristiques anatomiques et physicochimiques de ces fermenteurs digestifs, nous avons analysé les spécificités de leurs communautés procaryotiques liées à l’hôte, la variabilité individuelle, la structuration spatiale (inter- et intra- fermenteurs digestifs) et la dynamique temporelle (journalière et hebdomadaire) avec ou sans perturbation nutritionnelle induite

Curr Biol

Efference copies are neural replicas of motor outputs used to anticipate the sensory consequences of a self-generated motor action or to coordinate neural networks involved in distinct motor behaviors. An established example of this motor-to-motor coupling is the efference copy of the propulsive motor command, which supplements classical visuo-vestibular reflexes to ensure gaze stabilization during amphibian larval locomotion. Such feedforward replica of spinal pattern-generating circuits produces a spino-extraocular motor coupled activity that evokes eye movements, spatiotemporally coordinated to tail undulation independently of any sensory signal. Exploiting the developmental stages of the frog, studies in metamorphing Xenopus demonstrated the persistence of this spino-extraocular motor command in adults and its developmental adaptation to tetrapodal locomotion. Here, we demonstrate for the first time the existence of a comparable locomotor-to-ocular motor coupling in the mouse. In neonates, ex vivo nerve recordings of brainstem-spinal cord preparations reveal a spino-extraocular motor coupled activity similar to the one described in Xenopus. In adult mice, trans-synaptic rabies virus injections in lateral rectus eye muscle label cervical spinal cord neurons closely connected to abducens motor neurons. Finally, treadmill-elicited locomotion in decerebrated preparations evokes rhythmic eye movements in synchrony with the limb gait pattern. Overall, our data are evidence for the conservation of locomotor-induced eye movements in vertebrate lineages. Thus, in mammals as in amphibians, CPG-efference copy feedforward signals might interact with sensory feedback to ensure efficient gaze control during locomotion.Corrélats neurophysiologiques de l'évolution et du développement des stratégies de stabilisation du regard pendant la locomotion chez les vertébrésUniversité de Pari

X-linked myotubular myopathy is associated with epigenetic alterations and is ameliorated by HDAC inhibition

X-linked myotubular myopathy (XLMTM) is a fatal neuromuscular disorder caused by loss of function mutations in MTM1. At present, there are no directed therapies for XLMTM, and incomplete understanding of disease pathomechanisms. To address these knowledge gaps, we performed a drug screen in mtm1 mutant zebrafish and identified four positive hits, including valproic acid, which functions as a potent suppressor of the mtm1 zebrafish phenotype via HDAC inhibition. We translated these findings to a mouse XLMTM model, and showed that valproic acid ameliorates the murine phenotype. These observations led us to interrogate the epigenome in Mtm1 knockout mice; we found increased DNA methylation, which is normalized with valproic acid, and likely mediated through aberrant 1-carbon metabolism. Finally, we made the unexpected observation that XLMTM patients share a distinct DNA methylation signature, suggesting that epigenetic alteration is a conserved disease feature amenable to therapeutic intervention

Sea ice diatom contributions to Holocene nutrient utilization in East Antarctica

Combined high-resolution Holocene δ30Sidiat and δ13Cdiat paleorecords are presented from theSeasonal Ice Zone, East Antarctica. Both data sets reflect periods of increased nutrient utilization by diatomsduring the Hypsithermal period (circa 7800 to 3500 calendar years (cal years) B.P.), coincident with a higherabundance of open water diatom species (Fragilariopsis kerguelensis), increased biogenic silica productivity(%BSi), and higher regional summer temperatures. The Neoglacial period (after circa 3500 cal years B.P.) isreflected by an increase in sea ice indicative species (Fragilariopsis curta and Fragilariopsis cylindrus,upto50%) along with a decrease in %BSi and δ13Cdiat(< 18‰ to 23‰). However, over this period, δ30Sidiatdata show an increasing trend, to some of the highest values in the Holocene record (average of +0.43‰).Competing hypotheses are discussed to account for the decoupling trend in utilization proxies including ironfertilization, species-dependent fractionation effects, and diatom habitats. Based on mass balance calculations,we highlight that diatom species derived from the semi-enclosed sea ice environment may have a confoundingeffect upon δ30Sidowncorecompositions of the seasonal sea ice zone. A diatom composition, with approximately28% of biogenic silica derived from the sea ice environment (diat-SI) can account for the increased averagecompo sition of δ30Sidiatduring the Neoglacial. These data highlight the significant role sea ice diatoms can playwith relation to their export in sediment records, which has implications on productivity reconstructions fromthe seasonal ice zone

Platelets Alter Gene Expression Profile in Human Brain Endothelial Cells in an In Vitro Model of Cerebral Malaria

Platelet adhesion to the brain microvasculature has been associated with cerebral malaria (CM) in humans, suggesting that platelets play a role in the pathogenesis of this syndrome. In vitro co-cultures have shown that platelets can act as a bridge between Plasmodium falciparum-infected red blood cells (pRBC) and human brain microvascular endothelial cells (HBEC) and potentiate HBEC apoptosis. Using cDNA microarray technology, we analyzed transcriptional changes of HBEC in response to platelets in the presence or the absence of tumor necrosis factor (TNF) and pRBC, which have been reported to alter gene expression in endothelial cells. Using a rigorous statistical approach with multiple test corrections, we showed a significant effect of platelets on gene expression in HBEC. We also detected a strong effect of TNF, whereas there was no transcriptional change induced specifically by pRBC. Nevertheless, a global ANOVA and a two-way ANOVA suggested that pRBC acted in interaction with platelets and TNF to alter gene expression in HBEC. The expression of selected genes was validated by RT-qPCR. The analysis of gene functional annotation indicated that platelets induce the expression of genes involved in inflammation and apoptosis, such as genes involved in chemokine-, TREM1-, cytokine-, IL10-, TGFβ-, death-receptor-, and apoptosis-signaling. Overall, our results support the hypothesis that platelets play a pathogenic role in CM

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Etude de l'adhésion d'ostéoblastes sur substituts apatitiques par microscopie à force atomique

172 pagesThe aim of this work enters in the process of development of phosphocalcic apatite. The studied materials are silicated and carbonated Hydroxyapatite. It was a interdisciplinary work where synthesis and sintering of ceramics materials were studied and cellular behaviour on these materials are investigated. The original dimension of this work concern the following of the bone cell response using indentation by Atomic Force Microscope. We show that bioactivity of these materials are similar and that the relaxation of osteoblasts on TA6V and stoechiometric Hydroxyapatite follows a potency law with an exponent near 0.2.L'objectif de cette étude s'inscrit dans une démarche de développement de céramiques apatites phosphocalciques et de leur évaluation biologique. Les matériaux étudiés sont des hydroxyapatites silicatées ou carbonatés denses en monophasées. Il s'agit d'un travail interdisciplinaire, qui va de la synthèse et la mise en œuvre de matériaux céramiques à la biomécanique cellulaire et les essais de cultures cellulaires in vitro. La dimension originale du projet concerne le suivi de la réponse des cellules osseuses déposées sur ces céramiques par l'indentation à l'aide d'un AFM. Ces travaux montrent d'une part, que la bioactivité des matériaux étudiés était semblables et d'autre part, que la relaxation de cellules ensemencées sur TA6V et hydroxyapatite stochiométrique suivent une loi puissance (exposant ≈ 0.2) sur 2-200 secondes. La méthode originale utilisée montre par ailleurs que la relaxation d'une fibre d'actine est différentiable de la relaxation de la membrane cellulaire