138 research outputs found

    Steam and gas emission rates from La Soufrière of Guadeloupe (Antilles arc): implications for the magmatic supply degassing during unrest

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    Since its last magmatic eruption in 1530 AD, La Soufrière andesitic volcano in Guadeloupe has displayed intense hydrothermal activity and six phreatic eruptive crises (the last of which, in 1976-1977, with 73000 evacuees). Here we report on the first direct quantification of gas plume emissions from La Soufrière summit vents, which gradually intensified during the past 20 years. Gas fluxes were determined in 2006 then 2012 [1] by measuring the horizontal and vertical distribution of volcanic gas concentrations in the air-diluted plume, the composition of the hot fumarolic fluid at exit (108°C), and scaling to the speed of plume transport (in situ measurements and FLIR imaging). We first demonstrate that all fumarolic vents of La Soufrière are fed by a common H2O-rich (97-98 mol %) fluid end-member, emitted almost unmodified at the most active South Crater while affected by secondary alterations (steam condensation, sulphur scrubbing) at other vents. Daily fluxes in 2012 (200 tons of H2O, 15 tons of CO2, ~4 tons of H2S and 1 ton of HCl) were augmented by a factor ~3 compared to 2006, in agreement with increasing activity. Summit fumarolic degassing contributes most of the bulk volatile and heat budget (8 MW) of the volcano. Isotopic evidences demonstrate that La Soufrière hydrothermal emissions are sustained by continuous heat and gas supply from an andesitic magma reservoir confined at 6-7 km depth. This magmatic supply mixes with abundant groundwater of tropical meteoric origin in the hydrothermal system. Based on petro-geochemical data for the erupted magma(s), we assess that the volcanic gas fluxes in 2012 can be accounted for by the release of free magmatic gas derived from about 1000 m3 per day of the basaltic melt replenishing the reservoir at depth. In terms of mass budget, the current degassing unrest is compatible with enhanced free gas release from that reservoir, without requiring any (actually undetected) magma intrusion. We recommend a regular survey of the fumarolic gas flux from La Soufrière in order to anticipate the evolution of the magma reservoir. [1] P. Allard et al., Chemical Geology 384, 76-93, 2014

    DEEP RESERVOIR TEMPERATURES OF LOW-ENTHALPY GEOTHERMAL SYSTEMS IN TUNISIA: NEW CONSTRAINTS FROM CHEMISTRY OF THERMAL WATERS

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    Tunisia is characterized by hot and warm groundwaters (temperature up to 75 °C) which represent the surface manifestation of geothermal systems hosted in carbonate-evaporite rock sequences. The T-conditions of Tunisia deep thermal reservoirs are here evaluated for the first time at the regional scale. The results here shown clearly highlight the limitations inherent in the application of common geothermometric methods in the estimation of equilibrium temperatures in sedimentary environments. The modeling approach proposed by Chiodini et alii (1995), which makes use of the ratios between dissolved HCO3, SO4 and F, provides the most reliable results, and allows us to derive equilibrium temperatures up to 200 °C for the Tunisian thermal reservoirs. Very high equilibrium pCO2 (100 bar) values are also estimated, likely indicative of the confined aquifer conditions

    What Is the Optimal Duration of Adjuvant Mitotane Therapy in Adrenocortical Carcinoma? An Unanswered Question

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    A relevant issue on the treatment of adrenocortical carcinoma (ACC) concerns the optimal duration of adjuvant mitotane treatment. We tried to address this question, assessing whether a correlation exists between the duration of adjuvant mitotane treatment and recurrence-free survival (RFS) of patients with ACC. We conducted a multicenter retrospective analysis on 154 ACC patients treated for ≥12 months with adjuvant mitotane after radical surgery and who were free of disease at the mitotane stop. During a median follow-up of 38 months, 19 patients (12.3%) experienced recurrence. We calculated the RFS after mitotane (RFSAM), from the landmark time-point of mitotane discontinuation, to overcome immortal time bias. We found a wide variability in the duration of adjuvant mitotane treatment among different centers and also among patients cared for at the same center, reflecting heterogeneous practice. We did not find any survival advantage in patients treated for longer than 24 months. Moreover, the relationship between treatment duration and the frequency of ACC recurrence was not linear after stratifying our patients in tertiles of length of adjuvant treatment. In conclusion, the present findings do not support the concept that extending adjuvant mitotane treatment over two years is beneficial for ACC patients with low to moderate risk of recurrence

    Search for anomalies in the neutrino sector with muon spectrometers and large LArTPC imaging detectors at CERN

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    A new experiment with an intense ~2 GeV neutrino beam at CERN SPS is proposed in order to definitely clarify the possible existence of additional neutrino states, as pointed out by neutrino calibration source experiments, reactor and accelerator experiments and measure the corresponding oscillation parameters. The experiment is based on two identical LAr-TPCs complemented by magnetized spectrometers detecting electron and muon neutrino events at Far and Near positions, 1600 m and 300 m from the proton target, respectively. The ICARUS T600 detector, the largest LAr-TPC ever built with a size of about 600 ton of imaging mass, now running in the LNGS underground laboratory, will be moved at the CERN Far position. An additional 1/4 of the T600 detector (T150) will be constructed and located in the Near position. Two large area spectrometers will be placed downstream of the two LAr-TPC detectors to perform charge identification and muon momentum measurements from sub-GeV to several GeV energy range, greatly complementing the physics capabilities. This experiment will offer remarkable discovery potentialities, collecting a very large number of unbiased events both in the neutrino and antineutrino channels, largely adequate to definitely settle the origin of the observed neutrino-related anomalies.Comment: Contribution to the European Strategy for Particle Physics - Open Symposium Preparatory Group, Kracow 10-12 September 201

    Geographical heterogeneity of clinical and serological phenotypes of systemic sclerosis observed at tertiary referral centres. The experience of the Italian SIR-SPRING registry and review of the world literature

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    Introduction: Systemic sclerosis (SSc) is characterized by a complex etiopathogenesis encompassing both host genetic and environmental -infectious/toxic- factors responsible for altered fibrogenesis and diffuse microangiopathy. A wide spectrum of clinical phenotypes may be observed in patients' populations from different geographical areas. We investigated the prevalence of specific clinical and serological phenotypes in patients with definite SSc enrolled at tertiary referral centres in different Italian geographical macro-areas. The observed findings were compared with those reported in the world literature.Materials and methods: The clinical features of 1538 patients (161 M, 10.5%; mean age 59.8 +/- 26.9 yrs.; mean disease duration 8.9 +/- 7.7 yrs) with definite SSc recruited in 38 tertiary referral centres of the SPRING (Systemic sclerosis Progression INvestiGation Group) registry promoted by Italian Society of Rheumatology (SIR) were obtained and clustered according to Italian geographical macroareas.Results: Patients living in Southern Italy were characterized by more severe clinical and/or serological SSc phenotypes compared to those in Northern and Central Italy; namely, they show increased percentages of diffuse cutaneous SSc, digital ulcers, sicca syndrome, muscle involvement, arthritis, cardiopulmonary symptoms, interstitial lung involvement at HRCT, as well increased prevalence of serum anti-Scl70 autoantibodies. In the same SSc population immunusppressive drugs were frequently employed. The review of the literature underlined the geographical heterogeneity of SSc phenotypes, even if the observed findings are scarcely comparable due to the variability of methodological approaches.Conclusion: The phenotypical differences among SSc patients' subgroups from Italian macro-areas might be correlated to genetic/environmental co-factors, and possibly to a not equally distributed national network of information and healthcare facilities

    Low exposure long-baseline neutrino oscillation sensitivity of the DUNE experiment

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    The Deep Underground Neutrino Experiment (DUNE) will produce world-leading neutrino oscillation measurements over the lifetime of the experiment. In this work, we explore DUNE's sensitivity to observe charge-parity violation (CPV) in the neutrino sector, and to resolve the mass ordering, for exposures of up to 100 kiloton-megawatt-years (kt-MW-yr). The analysis includes detailed uncertainties on the flux prediction, the neutrino interaction model, and detector effects. We demonstrate that DUNE will be able to unambiguously resolve the neutrino mass ordering at a 3σ\sigma (5σ\sigma) level, with a 66 (100) kt-MW-yr far detector exposure, and has the ability to make strong statements at significantly shorter exposures depending on the true value of other oscillation parameters. We also show that DUNE has the potential to make a robust measurement of CPV at a 3σ\sigma level with a 100 kt-MW-yr exposure for the maximally CP-violating values \delta_{\rm CP}} = \pm\pi/2. Additionally, the dependence of DUNE's sensitivity on the exposure taken in neutrino-enhanced and antineutrino-enhanced running is discussed. An equal fraction of exposure taken in each beam mode is found to be close to optimal when considered over the entire space of interest

    A Gaseous Argon-Based Near Detector to Enhance the Physics Capabilities of DUNE

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    This document presents the concept and physics case for a magnetized gaseous argon-based detector system (ND-GAr) for the Deep Underground Neutrino Experiment (DUNE) Near Detector. This detector system is required in order for DUNE to reach its full physics potential in the measurement of CP violation and in delivering precision measurements of oscillation parameters. In addition to its critical role in the long-baseline oscillation program, ND-GAr will extend the overall physics program of DUNE. The LBNF high-intensity proton beam will provide a large flux of neutrinos that is sampled by ND-GAr, enabling DUNE to discover new particles and search for new interactions and symmetries beyond those predicted in the Standard Model

    Snowmass Neutrino Frontier: DUNE Physics Summary

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    The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino oscillation experiment with a primary physics goal of observing neutrino and antineutrino oscillation patterns to precisely measure the parameters governing long-baseline neutrino oscillation in a single experiment, and to test the three-flavor paradigm. DUNE's design has been developed by a large, international collaboration of scientists and engineers to have unique capability to measure neutrino oscillation as a function of energy in a broadband beam, to resolve degeneracy among oscillation parameters, and to control systematic uncertainty using the exquisite imaging capability of massive LArTPC far detector modules and an argon-based near detector. DUNE's neutrino oscillation measurements will unambiguously resolve the neutrino mass ordering and provide the sensitivity to discover CP violation in neutrinos for a wide range of possible values of δCP. DUNE is also uniquely sensitive to electron neutrinos from a galactic supernova burst, and to a broad range of physics beyond the Standard Model (BSM), including nucleon decays. DUNE is anticipated to begin collecting physics data with Phase I, an initial experiment configuration consisting of two far detector modules and a minimal suite of near detector components, with a 1.2 MW proton beam. To realize its extensive, world-leading physics potential requires the full scope of DUNE be completed in Phase II. The three Phase II upgrades are all necessary to achieve DUNE's physics goals: (1) addition of far detector modules three and four for a total FD fiducial mass of at least 40 kt, (2) upgrade of the proton beam power from 1.2 MW to 2.4 MW, and (3) replacement of the near detector's temporary muon spectrometer with a magnetized, high-pressure gaseous argon TPC and calorimeter

    Snowmass Neutrino Frontier: DUNE Physics Summary

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    The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino oscillation experiment with a primary physics goal of observing neutrino and antineutrino oscillation patterns to precisely measure the parameters governing long-baseline neutrino oscillation in a single experiment, and to test the three-flavor paradigm. DUNE's design has been developed by a large, international collaboration of scientists and engineers to have unique capability to measure neutrino oscillation as a function of energy in a broadband beam, to resolve degeneracy among oscillation parameters, and to control systematic uncertainty using the exquisite imaging capability of massive LArTPC far detector modules and an argon-based near detector. DUNE's neutrino oscillation measurements will unambiguously resolve the neutrino mass ordering and provide the sensitivity to discover CP violation in neutrinos for a wide range of possible values of δCP\delta_{CP}. DUNE is also uniquely sensitive to electron neutrinos from a galactic supernova burst, and to a broad range of physics beyond the Standard Model (BSM), including nucleon decays. DUNE is anticipated to begin collecting physics data with Phase I, an initial experiment configuration consisting of two far detector modules and a minimal suite of near detector components, with a 1.2 MW proton beam. To realize its extensive, world-leading physics potential requires the full scope of DUNE be completed in Phase II. The three Phase II upgrades are all necessary to achieve DUNE's physics goals: (1) addition of far detector modules three and four for a total FD fiducial mass of at least 40 kt, (2) upgrade of the proton beam power from 1.2 MW to 2.4 MW, and (3) replacement of the near detector's temporary muon spectrometer with a magnetized, high-pressure gaseous argon TPC and calorimeter.Comment: Contribution to Snowmass 202

    Reconstruction of interactions in the ProtoDUNE-SP detector with Pandora

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    The Pandora Software Development Kit and algorithm libraries provide pattern-recognition logic essential to the reconstruction of particle interactions in liquid argon time projection chamber detectors. Pandora is the primary event reconstruction software used at ProtoDUNE-SP, a prototype for the Deep Underground Neutrino Experiment far detector. ProtoDUNE-SP, located at CERN, is exposed to a charged-particle test beam. This paper gives an overview of the Pandora reconstruction algorithms and how they have been tailored for use at ProtoDUNE-SP. In complex events with numerous cosmic-ray and beam background particles, the simulated reconstruction and identification efficiency for triggered test-beam particles is above 80% for the majority of particle type and beam momentum combinations. Specifically, simulated 1 GeV/cc charged pions and protons are correctly reconstructed and identified with efficiencies of 86.1±0.6\pm0.6% and 84.1±0.6\pm0.6%, respectively. The efficiencies measured for test-beam data are shown to be within 5% of those predicted by the simulation.Comment: 39 pages, 19 figure
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