2,106 research outputs found
Scanning and data extraction from crop collecting mission documents
Poster presented at TDWG 2009, Montpellier (France). 9 - 13 Nov 2009
Magma storage, eruptive activity and flank instability: inferences from ground deformation and gravity changes during the 1993-2000 recharging of Mt. Etna volcano
A long recharging period characterized Mount Etna volcano during 1993-2000 before the main
explosive-effusive 2001 and 2002-03 flank eruptions. The joint analysis of ground deformation and gravity data over this entire period revealed that different phenomena occurred within Etna's plumbing system and clearly inferred two phases spanning 1993-97 and 1994-2000, respectively.
The first phase was characterized by magma storage and accumulation at an intermediate depth (2-6 km below sea level), which provoked an overall inflation and positive gravity changes. During the second phase, the magma started to rise and intrude at shallower levels favouring the
movement of the unstable eastern flank, which accelerated its sliding toward the East. The shallower magma accumulation also caused the gas exolution, associated with increasing
explosive activity at the summit craters, detected by a gravity negative variation. The gravity measurements, independently of the same result obtained by geochemical studies, confirm that only 20-30% of the magma volumes supplied in the plumbing system were then erupted. The
complex dynamic of rising magma beneath Mount Etna makes ground deformation and gravity measurements complementary, being able to detect different effects of magma emplacements beneath the surface. Our results also highlight how the joint use of ground deformation and gravity observations may be crucial in identifying the nature and rate of an impending season of
volcanic eruptions
Seismic-induced accelerations detected by two parallel gravity meters in continuous recording with a high sampling rate at Etna volcano
We analyse a microgravity data set acquired from two spring LaCoste & Romberg gravity meters operated in parallel at the same site on Etna volcano (Italy) for about two months (August â September 2005). The high sampling rate acquisition (2Hz) allowed the correlation of short-lasting gravity fluctuations with seismic events. After characterizing the oscillation behavior of the meters, through the study of spectral content and the background noise level of both sequences, we recognized fluctuations in the gravity data, spanning a range of periods from 1 second to about 30 seconds dominated by components with a period of about 15 Ă· 25 seconds, during time intervals encompassing both local seismic events and large worldwide earthquakes. The data analyses demonstrate that observed earthquake-induced gravity fluctuations have some differences due to diverse spectral content of the earthquakes. When local seismic events which present high frequency content excite the meters, the correlation between the two gravity signals is poor (factor < 0.3). Vice versa, when large worldwide earthquakes occur and low frequency seismic waves dominate the ensuing seismic wavefield, the resonance frequencies of the meters are excited and they react according to more common features. In the latter case, the signals from the two instruments are strongly correlated to each other (up to 0.9). In this paper the behaviors of spring gravimeters in the frequency range of the disturbances produced by local and large worldwide earthquakes are presented and discussed
Vectorial magnetometers for noise reduction in volcanomagnetic monitoring at Mt Etna
The volcanomagnetic monitoring is critically dependent on the ability to detect and isolate magnetic variations related to volcanic activity. Accurate detection of volcanomagnetic anomalies attributable to the volcanoâs dynamics requires removing from measurements of the earthâs magnetic field, fluctuations of external origin which may be up to hundreds of nanotesla during geomagnetic storms. The commonly used method of taking simple differences of the total intensity with respect to the simultaneous value at a remote reference is partially successful. Variations in the difference fields arise principally from contrasting electromagnetic properties at magnetometer sites. To improve the noise reduction of geomagnetic data from magnetic network of Mt Etna we developed an adaptive filtering. Magnetic vector data are included as input to the filter, to account for the orientation of the disturbance field. The filter is able to estimate and rectify the model parameters continuously by means of new observations, so that predictions match the observed data. The error of state estimation has been decreased and the filtering accuracy improved. Experimental data collected on Mt Etna during 2010 are analyzed to relate the field variation at a given station to the field at other sites filtering out undesired noise and enhancing signal-to-noise ratio
Toxicogenomics analysis of dynamic dose-response in macrophages highlights molecular alterations relevant for multi-walled carbon nanotube-induced lung fibrosis
Toxicogenomics approaches are increasingly used to gain mechanistic insight into the toxicity of engineered nanomaterials (ENMs). These emerging technologies have been shown to aid the translation of in vitro experimentation into relevant information on real-life exposures. Furthermore, integrating multiple layers of molecular alteration can provide a broader understanding of the toxicological insult. While there is growing evidence of the immunotoxic effects of several ENMs, the mechanisms are less characterized, and the dynamics of the molecular adaptation of the immune cells are still largely unknown. Here, we hypothesized that a multi-omics investigation of dynamic dose-dependent (DDD) molecular alterations could be used to retrieve relevant information concerning possible long-term consequences of the exposure. To this end, we applied this approach on a model of human macrophages to investigate the effects of rigid multi-walled carbon nanotubes (rCNTs). THP-1 macrophages were exposed to increasing concentrations of rCNTs and the genome-wide transcription and gene promoter methylation were assessed at three consecutive time points. The results suggest dynamic molecular adaptation with a rapid response in the gene expression and contribution of DNA methylation in the long-term adaptation. Moreover, our analytical approach is able to highlight patterns of molecular alteration in vitro that are relevant for the pathogenesis of pulmonary fibrosis, a known long-term effect of rCNTs exposure in vivo.Peer reviewe
Magnetic features of the magmatic intrusion occurred in 2007 eruption at Stromboli Island (Italy.)
Significant changes in the local magnetic field marked the resumption of the eruptive activity at Stromboli volcano on February 27, 2007. After differential magnetic fields were filtered from the external noise by adaptive filters and from the seasonal thermic noise using temperature data, we highlighted step-like changes of 1-4 nT coincident with the eruptive fissures opening in the upper part of the Sciara del Fuoco. The magnetic variations detected at 2 stations are closely related to the propagation of a shallow NE-SW magmatic intrusion outside the summit craters area . These observations are consistent with those calculated from piezomagnetic models, where stress-induced changes in rock magnetization are produced by the magmatic intrusion. No significant magnetic changes were observed when the first fractures opened along the NE crater rim. Indeed, the stress-induced magnetization caused by this magmatic activity is expected to be too low because of the structural weakness and/or thermal state of the summit area. The continuous long-term decay characterizing the post-eruptive magnetic pattern was related to a time-dependent relaxation process. A Maxwell rheology was assumed and the temporal evolution of the piezomagnetic field was evaluated. This allowed for the estimate of the rheological properties of the medium, in particular an average viscosity ranging between 1016 and 1017 Païs was achieved involving a relaxation time Ï of about 38 days
Correction: Rheometry-on-a-chip: measuring the relaxation time of a viscoelastic liquid through particle migration in microchannel flows
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Heavy-flavour production in Pb-Pb collisions at the LHC, measured with the ALICE detector
We present the first results from the ALICE experiment on the nuclear
modification factors for heavy-flavour hadron production in Pb-Pb collisions at
sqrt{s_NN}=2.76 TeV. Using proton-proton and lead-lead collision samples at
sqrt{s}=7 TeV and sqrt{s_NN}=2.76 TeV, respectively, nuclear modification
factors R_AA(pt) were measured for D mesons at central rapidity (via displaced
decay vertex reconstruction), and for electrons and muons, at central and
forward rapidity, respectively.Comment: 8 pages, 5 figures, plenary talk at Quark Matter 2011, Annecy, Franc
A prototype of a large tunable FabryâPĂ©rot interferometer for solar spectroscopy
Large Fabry-PĂ©rot Interferometers (FPIs) are used in a variety of astronomical instrumentation, including spectro-polarimeters for 4 m class solar telescopes. In this work we comprehensively characterize the cavity of a prototype 150 mm FPI, sporting a novel, fully symmetric design. Of particular interest, we define a new method to properly assess the gravity effects on the interferometer's cavity when the system is used in either the vertical or horizontal configuration, both typical of solar observations. We show that the symmetric design very effectively limits the combined effects of pre-load and gravity forces to only a few nm over a 120 mm diameter illuminated surface, with gravity contributing ~2 nm peak-to-valley (~0.3 nm rms) in either configuration. We confirm a variation of the tilt between the plates of the interferometer during the spectral scan, which can be mitigated with appropriate corrections to the spacing commands. Finally, we show that the dynamical response of the new system fully satisfies typical operational scenarios. We conclude that large, fully symmetric FPIs can be safely used within solar instrumentation in both, horizontal and vertical position, with the latter better suited to limiting the overall volume occupied by such an instrument
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