981 research outputs found

    Supermassive black hole pairs in clumpy galaxies at high redshift: delayed binary formation and concurrent mass growth

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    Massive gas-rich galaxy discs at z∌1−3z \sim 1-3 host massive star-forming clumps with typical baryonic masses in the range 107−10810^7-10^8~M⊙_{\odot} which can affect the orbital decay and concurrent growth of supermassive black hole (BH) pairs. Using a set of high-resolution simulations of isolated clumpy galaxies hosting a pair of unequal-mass BHs, we study the interaction between massive clumps and a BH pair at kpc scales, during the early phase of the orbital decay. We find that both the interaction with massive clumps and the heating of the cold gas layer of the disc by BH feedback tend to delay significantly the orbital decay of the secondary, which in many cases is ejected and then hovers for a whole Gyr around a separation of 1--2 kpc. In the envelope, dynamical friction is weak and there is no contribution of disc torques: these lead to the fastest decay once the orbit of the secondary BH has circularised in the disc midplane. In runs with larger eccentricities the delay is stronger, although there are some exceptions. We also show that, even in discs with very sporadic transient clump formation, a strong spiral pattern affects the decay time-scale for BHs on eccentric orbits. We conclude that, contrary to previous belief, a gas-rich background is not necessarily conducive to a fast BH decay and binary formation, which prompts more extensive investigations aimed at calibrating event-rate forecasts for ongoing and future gravitational-wave searches, such as with Pulsar Timing Arrays and the future evolved Laser Interferometer Space Antenna.Comment: Accepted by MNRA

    Quality of Life and Personality Traits in Patients with Malignant Pleural Mesothelioma and Their First-Degree Caregivers.

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    Asbestos exposure causes significant pleural diseases, including malignant pleural mesothelioma (MPM). Taking into account the impact of MPM on emotional functioning and wellbeing, this study aimed to evaluate the quality of life and personality traits in patients with MPM and their first-degree caregivers through the World Health Organization Quality of Life–BREF (WHOQOL-BREF) and the Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF). The sample was composed of 27 MPM patients, 55 first-degree relatives enrolled in Casale Monferrato and Monfalcone (Italy), and 40 healthy controls (HC). Patients and relatives reported poorer physical health than the HC. Patients had a higher overall sense of physical debilitation and poorer health than relatives and the HC, more numerous complaints of memory problems and difficulties in concentrating, and a greater belief that goals cannot be reached or problems solved, while often claiming that they were more indecisive and inefficacious than the HC. First-degree relatives reported lower opinions of others, a greater belief that goals cannot be reached or problems solved, support for the notion that they are indecisive and inefficacious, and were more likely to suffer from fear that significantly inhibited normal activities than were HC. In multinomial regression analyses, partial models indicated that sex, physical comorbidities, and the True Response Inconsistency (TRIN-r), Malaise (MLS), and Behavior-Restricting Fears (BRF) dimensions of the MMPI-2-RF had significant effects on group differences. In conclusion, health care providers should assess the ongoing adjustment and emotional wellbeing of people with MPM and their relatives, and provide support to reduce emotional distress

    Conduit dynamics and post-explosion degassing on Stromboli:a combined UV camera and 1 numerical modelling treatment

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    Recent gas flux measurements have shown that strombolian explosions are often followed by periods of elevated flux, or ‘gas codas’, with durations of order a minute. Here, we present UV camera data from 200 events recorded at Stromboli volcano to constrain the nature of these codas for the first time, providing estimates for combined explosion plus coda SO2 masses of ≈ 18 – 225 kg. Numerical simulations of gas slug ascent show that substantial proportions of the initial gas mass can be distributed into a train of ‘daughter bubbles’ released from the base of the slug, which we suggest, generate the codas, on bursting at the surface. This process could also cause transitioning of slugs into cap bubbles, significantly reducing explosivity. This study is the first attempt to combine high temporal resolution gas flux data with numerical simulations of conduit gas flow to investigate volcanic degassing dynamics

    Passive vs. active degassing modes at an open-vent volcano (Stromboli, Italy)

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    We report here on a UV-camera based field experiment performed on Stromboli volcano during 7 days in 2010 and 2011, aimed at obtaining the very first simultaneous assessment of all the different forms (passive and active) of SO2 release from an open-vent volcano. Using the unprecedented spatial and temporal resolution of the UV camera, we obtained a 0.8 Hz record of the total SO2 flux from Stromboli over a timeframe of 14 h, which ranged between 0.4 and 1.9 kg s 1 around a mean value of 0.7 kg s 1 and we concurrently derived SO2 masses for more than 130 Strombolian explosions and 50 gas puffs. From this, we show erupted SO2 masses have a variability of up to one order of magnitude, and range between 2 and 55 kg (average 20 kg), corresponding to a time integrated flux of 0.0570.01 kg s 1. Our experimental constraints on individual gas puff mass (0.03–0.42 kg of SO2, averaging 0.19 kg) are the first of their kind, equating to an emission rate ranging from 0.02 to 0.27 kg s 1. On this basis, we conclude that puffing is two times more efficient than Strombolian explosions in the magmatic degassing process, and that active degassing (explosionsĂŸpuffing) accounts for 23% (ranging from 10% to 45%) of the volcano’s total SO2 flux, e.g., passive degassing between the explosions contributes the majority ( 77%) of the released gas. We furthermore integrate our UV camera gas data for the explosions and puffs, with independent geophysical data (infrared radiometer data and very long period seismicity), to offer key and novel insights into the degassing dynamics within the shallow conduit systems of this open-vent volcano

    Observability of Forming Planets and their Circumplanetary Disks I. -- Parameter Study for ALMA

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    We present mock observations of forming planets with ALMA. The possible detections of circumplanetary disks (CPDs) were investigated around planets of Saturn, 1, 3, 5, and 10 Jupiter-masses that are placed at 5.2 AU from their star. The radiative, three dimensional hydrodynamic simulations were then post-processed with RADMC3D and the ALMA Observation Simulator. We found that even though the CPDs are too small to be resolved, they are hot due to the accreting planet in the optically thick limit, therefore the best chance to detect them with continuum observations in this case is at the shortest ALMA wavelengths, such as Band 9 (440 microns). Similar fluxes were found in the case of Saturn and Jupiter-mass planets, as for the 10 MJup\mathrm{M_{Jup}} gas-giant, due to temperature weighted optical depth effects: when no deep gap is carved, the planet region is blanketed by the optically thick circumstellar disk leading to a less efficient cooling there. A test was made for a 52 AU orbital separation, showed that optically thin CPDs are also detectable in band 7 but they need longer integration times (>>5hrs). Comparing the gap profiles of the same simulation at various ALMA bands and the hydro simulation confirmed that they change significantly, first because the gap is wider at longer wavelengths due to decreasing optical depth; second, the beam convolution makes the gap shallower and at least 25% narrower. Therefore, caution has to be made when estimating planet masses based on ALMA continuum observations of gaps.Comment: Accepted for publication at MNRAS. Typos are corrected since previous version. 11 pages, 5 tables, 4 figure

    Mercury emissions from soils and fumaroles of Nea Kameni volcanic centre, Santorini (Greece)

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    There have been limited studies to date targeting mercury emissions from volcanic fumarolic systems, and no mercury flux data exist for soil or fumarolic emissions at Santorini volcanic complex, Greece. We present results from the first geochemical survey of Hg and major volatile (CO2, H2S, H2O and H2) concentrations and fluxes in the fumarolic gases released by the volcanic/hydrothermal system of Nea Kameni islet; the active volcanic center of Santorini. These data were obtained using a portable mercury spectrometer (Lumex 915+) for gaseous elemental mercury (GEM) determination, and a Multi-component Gas Analyzer System (Multi-GAS) for major volatiles. Gaseous Elemental Mercury (GEM) concentrations in the fumarole atmospheric plumes were systematically above background levels (~4 ng GEM m-3), ranging from ~4.5 to 121 ng GEM m-3. Variability in the measured mercury concentrations may result from changes in atmospheric conditions and/or unsteady gas release from the fumaroles. We estimate an average GEM/CO2 mass ratio in the fumarolic gases of Nea Kameni of approximately 10-9, which falls in the range of values obtained at other low-T (100°C) volcanic/hydrothermal systems (~10-8); our measured GEM/H2S mass ratio (10-5) also lies within the accepted representative range (10-4 to 10-6) of non-explosive volcanic degassing. Our estimated mercury flux from Nea Kameni's fumarolic field (2.56 × 10-7 t yr-1), while making up a marginal contribution to the global volcanic non-eruptive GEM emissions from closed-conduit degassing volcanoes, represents the first available assessment of mercury emissions at Santorini volcano, and will contribute to the evaluation of future episodes of unrest at this renowned volcanic complex

    Hydrogen in the gas plume of an open-vent volcano, Mount Etna, Italy

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    We report here on the first hydrogen determinations in the volcanic gas plume of Mount Etna, in Italy, which we obtained during periodic field surveys on the volcano’s summit area with an upgraded MultiGAS. Using a specific (EZT3HYT) electrochemical sensor, we resolved H2 concentrations in the plume of 1–3 ppm above ambient (background) atmosphere and derived H2‐SO2 and H2‐H2O plume molar ratios of 0.002–0.044 (mean 0.013) and 0.0001–0.0042 (mean 0.0018), respectively. Taking the above H2‐SO2 ratios in combination with a time‐averaged SO2 flux of 1600 Gg yr−1, we evaluate that Etna contributes a time‐averaged H2 flux of ∌0.65 Gg yr−1, suggesting that the volcanogenic contribution to the global atmospheric H2 budget (70,000–100,000 Gg yr−1) is marginal. We also use our observed H2‐H2O ratios to propose that Etna’s passive plume composition is (at least partially) representative of a quenched (temperatures between 750°C and 950°C) equilibrium in the gas‐magma system, at redox conditions close to the nickel‐nickel oxide (NNO) mineral buffer. The positive dependence between H2‐SO2, H2‐H2O, and CO2‐SO2 ratios suggests that H2 is likely supplied (at least in part) by deeply rising CO2‐rich gas bubbles, fluxing through a CO2‐depleted shallow conduit magma.PublishedB102041.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive2.4. TTC - Laboratori di geochimica dei fluidiJCR Journalrestricte

    AB0901 PREVALENCE OF OSTEOPOROSIS IN ITALIAN POSTMENOPAUSAL WOMEN ACCORDING TO DEFRA ALGORITHM

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    Background:Osteoporosis is a recognized health problem and the burden of the disease is mostly associated with the occurrence of hip and vertebral fracture.Objectives:This study was aimed at evaluating the prevalence of osteoporosis in Italian postmenopausal women, defined by DeFRA calculation as a 10 years fracture risk equal or higher than 20%.Methods:This is a monocenter cohort study evaluating 1850 post-menopausal women aged 50 years and older. All the participants were evaluated as far as anthropometrics. Defra questionnaire was administered and calculated with bone mineral density (DXA) measured at lumbar spine and femoral neck.Results:The prevalence of osteoporosis as assessed by DeFRA was 29.8% in the whole population, according to literature. The frequency of a risk fracture equal or higher than 20% varied from 7.9% in the group aged 50-59 years to 35% in subjects aged >80. Among clinical risk factors for fracture, the presence of a previous fracture (spine primarily) was the most commonly observed.Conclusion:Our data showed that about one third of post-menopausal women aged 50 and older in Italy has osteoporosis on the basis of DeFRA algorithm, with a high 10 years fracture risk. A previous fracture is the most common risk factor. The data should be considered in relation to the need to increase prevention strategies and therapeutic intervention.Disclosure of Interests:None declare

    THE EFFECT OF ROAD CAMBER ON RUNNING KINEMATICS

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    Camber, or the crown of roads used for drainage purposes, has been implicated as a cause of overuse injuries, including iliotibial band syndrome, in runners. The purpose of this investigation was to study the effects of varying degrees of simulated road camber and different running velocities on lower extremity kinematics. Using three-dimensional motion analysis, bilateral hip, knee, and ankle angles of 5 injury-free recreational runners were investigated. Subjects were videotaped while running on level and variable cambered surfaces at 6.0 and 7.0 mph. Post-hoc analysis found significant differences between right and left limbs between the right knee at toe off condition 1, 7.0 mph compared to right knee at toe off condition 2, 7.0 mph (
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