Monitoring temporal opacity fluctuations of large structures with muon tomography : a calibration experiment using a water tower tank

Usage of secondary cosmic muons to image the geological structures density distribution significantly developed during the past ten years. Recent applications demonstrate the method interest to monitor magma ascent and volcanic gas movements inside volcanoes. Muon radiography could be used to monitor density variations in aquifers and the critical zone in the near surface. However, the time resolution achievable by muon radiography monitoring remains poorly studied. It is biased by fluctuation sources exterior to the target, and statistically affected by the limited number of particles detected during the experiment. The present study documents these two issues within a simple and well constrained experimental context: a water tower. We use the data to discuss the influence of atmospheric variability that perturbs the signal, and propose correction formulas to extract the muon flux variations related to the water level changes. Statistical developments establish the feasibility domain of muon radiography monitoring as a function of target thickness (i.e. opacity). Objects with a thickness comprised between $\simeq$ 50 $\pm$ 30m water equivalent correspond to the best time resolution. Thinner objects have a degraded time resolution that strongly depends on the zenith angle, whereas thicker objects (like volcanoes) time resolution does not.Comment: 11 pages, 9 figures. Final version published in Scientific Reports, Nature, 14 march 201

Bacterial toxins modifying the actin cytoskeleton

Numerous bacterial toxins recognize the actin cytoskeleton as a target. The clostridial binary toxins (Iota and C2 families) ADP-ribosylate the actin monomers causing the dissociation of the actin filaments. The large clostridial toxins from Clostridium difficile, Clostridium sordellii and Clostridium novyi inactivate, by glucosylation, proteins from the Rho family that regulate actin polymerization. In contrast, the cytotoxic necrotic factor from Escherichia coli activates Rho by deamidation and increases the formation of actin filaments. The enterotoxin of Bacteroides fragilis is a protease specific for E-cadherin and it promotes the reorganization of the actin cytoskeleton. The bacterial toxins that modify the actin cytoskeleton induce various cell disfunctions including changes in cell barrier permeability and disruption of intercellular junctions

Mode family identification of a blisk by tip timing measurements

The study consists in tip timing measurements to identify a mode belonging to a certain family (flexural, torsional, etc). It can be performed placing different probes over blade tip profile and, thus, relating its deformed state with a mode family. The identification is performed for modes generating either standing or travelling wave response. It is followed by amplitude and phase distribution calculation of each blade for identification of nodal diameters number. Additionally a frequency response is obtained in order to calculate modal damping ratio

Damping coefficient estimation of a squeeze-film damper operating in a dual shaft test rig

Squeeze film dampers (SFD) are used to reduce dynamical loads in rotating machinery or to improve their performances in numerous industrial applications. The present paper considers the response of a dual shaft system with a SFD mounted on one of its bearings. The study is concerned with the overall system's dynamics in presence of a sealed SFD bearing with a lateral feeding groove and more specifically with the characterization of such damper in operational conditions. The design characteristics of the SFD are based on the linear approximation and the optimization w.r.t. sensitivity of appropriate eigenmodes of a numerical model of the dual shaft test rig. In order to gain more insight into the SFD operation, the experimental kinematic and pressure measurements data are processed within a numerical model of the fluid film using the short bearing approximation of the Reynolds equation and taking into account the flow into the groove. The work holds for low Reynolds number and completely sealed SFD were vapour cavitation is completely absent

Etude du comportement vibratoire des redresseurs sectorisés monobloc : approches numérique et expérimentale

Les redresseurs de compresseur de turbomachine axiale sont soumis à de la fatigue vibratoire. Or leur réalisation par assemblage de secteurs monobloc rend leur modélisation difficile (absence de symétrie cyclique, sensibilité au désaccordage). Le but est de présenter une stratégie de calcul robuste basée sur une modélisation stochastique de la structure et sur un calcul instationnaire tridimensionnel du chargement fluide. Des essais réalisés sur le compresseur HP multiétages CREATE permettent d'évaluer les niveaux de vibration sur un secteur de redresseur instrumenté pour valider le modèl

A 36 ka environmental record in the southern tropics : Lake Tritrivakely (Madgascar) (Un enregistrement de l'environnement depuis 36 ka en zone tropicale sud : le lac Tritrivakely (Madagascar)).

The upper 13 m of a 40 m-long sedimentary profile core taken in a crater lake on the Malagasy Plateau reveals 36,000 yrs of hydroclimatic evolution. A shallow lake occupies the core site from ≃35 to ≃19 ka BP under climatic conditions cooler than today. The water table is very low and biological productivity extremely reduced during the Last Glacial Maximum. A large warming was initiated at ≃14.5 ka BP. The modern bog establishes about 4 ka ag

Fatal Disseminated Acanthamoeba lenticulata Acanthamebiasis in a Heart Transplant Patient

We report a fatal case of disseminated acanthamebiasis caused by Acanthamoeba lenticulata (genotype T5) in a 39-year-old heart transplant recipient. The diagnosis was based on skin histopathologic results and confirmed by isolation of the ameba from involved skin and molecular analysis of a partial 18S rRNA gene sequence (DF3)

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

Correction to: Cluster identification, selection, and description in Cluster randomized crossover trials: the PREP-IT trials

An amendment to this paper has been published and can be accessed via the original article