45 research outputs found

    Muon tomography applied to active volcanoes

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    Muon tomography is a generic imaging method using the differential absorption of cosmic muons by matter. The measured contrast in the muons flux reflects the matter density contrast as it does in conventional medical imaging. The applications to volcanology present may advantadges induced by the features of the target itself: limited access to dangerous zones, impossible use of standard boreholes information, harsh environmental conditions etc. The Diaphane project is one of the largest and leading collaboration in the field and the present article summarizes recent results collected on the Lesser Antilles, with a special emphasis on the Soufri\`ere of Guadeloupe.Comment: 7 pages, 7 figures, International Conference on New Photo-detectors,PhotoDet2015, 6-9 July 2015, Moscow, Troitsk, Russia. Submitted to Po

    Design and operation of a field telescope for cosmic ray geophysical tomography

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    International audienceThe cosmic ray muon tomography gives an access to the density structure of geological targets. In the present article we describe a muon telescope adapted to harsh environmental conditions. In particular the design optimizes the total weight and power consumption to ease the deployment and increase the autonomy of the detector. The muon telescopes consist of at least two scintillator detection matrices readout by photosensors via optical fibres. Two photosensor options have been studied. The baseline option foresees one multianode photomultiplier (MAPM) per matrix. A second option using one multipixel photon counter (MPPC) per bar is under development. The readout electronics and data acquisition system developed for both options are detailed. We present a first data set acquired in open-sky conditions compared with the muon flux detected across geological objects

    Cell therapy of Duchenne muscular dystrophy: preclinical trial in GRMD dogs

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    Duchenne muscular dystrophy (DMD), a genetic progressive X-linked muscular dystrophy, is the most common genetic disease in humans. Cell therapy based on the use of somatic stem cells is a very promising approach. In a dog myopathy model, we isolated a muscle stem cell (MuStem) with the essential requirements for therapeutic use: high amplification capacity, ability to fuse with muscle fibers, renewal of the satellite cell population, dispersion in the whole body after vascular administration, persistence of long-term effect, and dramatic clinical improvement of treated animals. These preclinical results pave the way for a therapeutic trial in children with Duchenne muscular dystrophy.La dystrophie musculaire de Duchenne (DMD) est une maladie génétique progressive du muscle liée au chromosome X. Elle est la maladie génétique la plus fréquente chez l'homme. La thérapie cellulaire basée sur l'utilisation de cellules souches somatiques est une voie thérapeutique riche d'intérêt. Nous avons isolé, chez un modèle de chien myopathe, une cellule souche musculaire (MuStem) qui présente les qualités indispensables à une utilisation thérapeutique: forte capacité d'amplification, capacité à fusionner avec les fibres musculaires, renouvellement du contingent de cellules satellites, dispersion dans l'organisme après administration vasculaire, persistance de l'effet à long terme, spectaculaire amélioration clinique des animaux traités. Ces résultats précliniques ouvrent la voie à un essai thérapeutique chez l'enfant atteint de dystrophie musculaire de Duchenne

    DIAPHANE: Muon tomography applied to volcanoes, civil engineering, archaelogy

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    International audienceMuography techniques applied to geological structures greatly improved in the past ten years. Recent applications demonstrate the interest of the method not only to perform structural imaging but also to monitor the dynamics of inner movements like magma ascent inside volcanoes or density variations in hydrothermal systems. Muography time-resolution has been studied thanks to dedicated experiments, e.g. in a water tower tank. This paper presents the activities of the DIAPHANE collaboration between particle- and geo-physicists and the most recent results obtained in the field of volcanology, with a focus on the main target, the Soufrière of Guadeloupe active volcano. Special emphasis is given on the monitoring of the dome's inner volumes opacity variations, that could be ascribed to the hydrothermal system dynamics (vaporization of inner liquid water in coincidence with the appearance of new fumaroles at the summit). I also briefly present results obtained in the fields of civil engineering (study of urban underground tunnels) and archaelogy (greek tumulus scanning)

    Applied muography : from volcanology to archaelogy with a mobile muon detector (DIAPHANE / ARCHĂ©)

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    International audienceSince a decade the DIAPHANE collaboration has developed many detection methods in the context of volcanology to end up with the most complete existing muon detection complex on the dome of La Soufrière of Guadeloupe. Up-to-now 6 detectors are operating around this dome allowing both structural 3D imaging and functional continuous monitoring of the hydrothermal system. Although the volcanic dome has ideal proportions for muography studies in terms of opacity and timescales, it has recently emerged that applications in different fields may be worth a dedicated measurement campaign.Non invasive and non destructive measurements are a natural applications of muography in the industrial context as long as the relative opacity is large enough to be detected in a reasonable timescale. We present here the details of an upgraded mobile muon detector aimed at performing measurements on different points around the Apollonia tumulus near Thessaloniki in the North of Greece (ARCHé project). The detector has been installed for a 3 months data taking campaign in July 2018. The aim is to perform a 3D map of the tumulus and to correlate it with the results obtained previously in electrical tomography.We also show the results of a full Monte-Carlo study of the experiment, including the evaluation of the low-energy muons scattering on the target, just upstream the detector, mimicing a through-going particles. This irreducible background noise may bias the muography analysis and requires a prior characterization to conveniently correct the obtained results

    Monitoring muon flux variations besides and on a tunnel-boring machine

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    International audienceTunnel-boring projects require a considerable amount of planning, well ahead of drilling operations. Despite these precautionary measures, unexpected ground geological features (local density variations, cavities, unstable superficial ground, instabilities induced by the driller) impose real-time adaptations of the drilling operations.The direct relation of muon flux absorption with the density of a given medium, makes muography a promising solution to provide a real-time density analysis of geological objects in front of the tunnel-boring machine (TBM). To test its applicability during the drilling of the "Grand Paris Express" subway network, a muon telescope was used in two different experiments. First it was placed besides the TBM, directed towards the drilled cylinder from a lateral perspective. It was then moved directly inside the TBM for the rest of the drilling operation. These experiments provide an unique dataset to optimize the methodology.The data interpretation remains technically challenging due to the poissonian nature of muon events. The muon flux is estimated through the averaging of point events during a limited time window, leading to possible misinterpretations of pure statistically natural fluctuations of the muons events. Numerical routines have been developed to compute the theoretical muon flux variations for different drilling trajectories, depths, and speeds, in a medium with heteregenous density.For the first experiment, good matches are obtained with experimental values. A blind analysis of the reconstructed TBM's time dependant position puts strong constraints on the time and spatial resolution of the method. For the second data set, because the telescope is moving forward and at an irregular pace, the muon flux crossing a particular geological object measured by the telescope has different directions with respect to time, allowing 3D density estimates. First attempts to reconstruct 3D density distribution of the ground, using inhomogeneous poisson likelihood, are presented

    Muon imaging and monitoring at the Mont Terri underground rock laboratory, Switzerland.

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    International audienceImaging geological objects by quantifying the screening effect they have on the natural flux of cosmic muons is a powerful method that complements standard geophysical tools in the understanding of the Earth's subsurface. Radiographies of the average density of geological bodies along the muon paths can be retrieved from muon measurements, allowing to image large volumes of rock from a single observation point. Furthermore, continuous muon measurements allow us to monitor density variations in a geological object, by tracking the time changes in the outgoing flux of muons. The Mont Terri underground rock laboratory is located in the Jura Mountains range, at a depth of around 300 meters below the Earth's surface in north-western Switzerland. Its structural setting is dominated by an anticline of Triassic-Jurassic formations, whose spatial distribution is finely characterized given the numerous boreholes and outcrops studied inside and outside the tunnel. In this work we analyze 5 muon imaging experiences performed from inside the rock laboratory from 2013 to 2017. From this dataset we obtain corresponding muon radiographies of the average density between the tunnel and the surface of the Mont Terri site at extensive directions. Moreover, at one site the muon detector continuously recorded data for a whole year. We use these data to study the density variations due to changes on the rock's fluid saturation over time in different regions of the mountain. Finally, we perform a joint interpretation with complementary geological, meteorological and geophysical data from the site

    Nematode dermatitis due to Angiostrongylus vasorum infection in a dog

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    BACKGROUND: Angiostrongylus vasorum is a nematode that primarily infects Canidae. The adult parasites are found in the pulmonary arterial circulation and the right side of the heart. The most common clinical sign is respiratory dysfunction. Bleeding, neurological, ocular, cardiovascular and gastrointestinal disorders are also reported. Skin lesions are very unusual. HYPOTHESIS/OBJECTIVES: This report describes a nematode dermatitis due to A. vasorum infection. To the best of the authors' knowledge, this is the first case of a dog infected with this parasite that initially presented with skin lesions only. ANIMAL: A 3-year-old female Weimaraner dog presented with a crusted papular dermatitis on the bridge of the nose and on the pinnae, and an erythematous pododermatitis with erosions and perionyxis of one digit of 1 week's duration. Two weeks later the dog developed respiratory distress. METHODS AND RESULTS: Skin scrapings and fungal culture were negative for parasites and dermatophytes. Histopathological examination showed dermal granulomas and pyogranulomas with eosinophils centred around parasitic elements compatible with nematode larvae. Angiostrongylus vasorum DNA was demonstrated in skin biopsies. Chest radiographs were compatible with verminous pneumonia and a Baermann test revealed A. vasorum larvae. The dog was treated orally with fenbendazole, with rapid improvement and complete cure after 3 months. CONCLUSIONS AND CLINICAL IMPORTANCE: Angiostrongylus vasorum should be considered in dogs presented with skin lesions and respiratory signs. Skin biopsy, chest radiographs and Baermann test should be included in the diagnostic investigation

    Monitoring the La Soufrière de Guadeloupe hydrothermal system with a regularly-spaced muon telescope network

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    International audienceLong-term muon tomography allows to track density changes in a volcano bycontinuously measuring the flux of cosmic muons traversing the geological body. In thecontext of volcanic hydrothermal systems, this approach can help to determine zones ofpreferred steam formation, condensation, water infiltration and storage. A single muontelescope provides an integrated 2-D average-density section of a volcanic system,leading to an intrinsically ambiguous inverse problem. To overcome this limitation, wepresent the first results of imaging the La Soufrière de Guadeloupe dome and shallowhydrothermal system with several simultaneous muon telescopes viewing the domefrom different positions around its base. Our strategy provides better constraints on thespatial location of the density changes and an improved estimate of the amount of massinvolved in these changes. Therefore, we can better characterize water phase changesand estimate pore pressures. We compare the temporal density variations extractedfrom different muon telescopes to time-series of rainfall on the summit recharge areaand temperature profiles in the vicinity of ground thermal anomalies and summitfumaroles

    Long-term muon measurements to track density changes at La Soufrière de Guadeloupe volcano

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    International audienceVolcanoes in the Caribbean often host extremely developed hydrothermal systems. These result from the interaction of large amount of water, infiltered in the system thanks to strong precipitation regimes, with the magmatic gases and liquids rising from the magmatic chamber. Volcanic hydrothermal systems give rise to unpredictable hazards such as hydrothermal explosions, partial edifice collapse, mudflows and sudden emission of toxic gases. Characterizing the dynamics of these systems is thus critical for developing efficient risk assessment.At La Soufriere de Guadeloupe volcano, a pioneer network of muon telescopes has been installed to assess the potential of this technology to monitor the volcano's dynamic hydrothermal system. Muon imaging has emerged as a powerful method to complement standard geophysical methods in volcanology. Muon measurements yield a radiography of the average density along the muon path, allowing to image large volumes of a geological body from a single observation point. When multiple muon detectors surrounding the volcano are available, it is possible to invert these data to retrieve the 3-D density distribution in the volcano. Long-term measurements of the muon flux allow to infer density changes in the system. In the context of volcanic hydrothermal systems, this approach helps to characterize zones of steam formation, condensation, water infiltration and storage.Here we present the use of continuous muon measurements at La Soufrière de Guadeloupe volcano as a novel methodology to characterize the spatio-temporal dynamics of its hydrothermal system. In this work a set of more than 1.5 years of continuous measurements simultaneously acquired with two muon detectors is analyzed. The two telescopes scan two different zones of the dome with large overlapping volumes. The changes observed are consistent among the two detectors, thus pointing to a common source of density changes inside the volcano. The method is thus a reliable tool to monitor shallow activity in the volcano and may be used in other "wet volcanoes" in combination with standard monitoring methods to quantification internal processes of mass and heat transfer in the system
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