736 research outputs found

    Surface deformation of active volcanic areas retrieved with the SBAS-DInSAR technique: an overview

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    This paper presents a comprehensive overview of the surface deformation retrieval capability of the Differential Synthetic Aperture Radar Interferometry (DInSAR) algorithm, referred to as Small BAseline Subset (SBAS) technique, in the context of active volcanic areas. In particular, after a brief description of the algorithm some experiments relevant to three selected case-study areas are presented. First, we concentrate on the application of the SBAS algorithm to a single-orbit scenario, thus considering a set of SAR data composed by images acquired on descending orbits by the European Remote Sensing (ERS) radar sensors and relevant to the Long Valley caldera (eastern California) area. Subsequently, we address the capability of the SBAS technique in a multipleorbit context by referring to Mt. Etna volcano (southern Italy) test site, with respect to which two different ERS data set, composed by images acquired both on ascending and descending orbits, are available. Finally, we take advantage of the capability of the algorithm to work in a multi-platform scenario by jointly exploiting two different sets of SAR images collected by the ERS and the Environment Satellite (ENVISAT) radar sensors in the Campi Flegrei caldera (southern Italy) area. The presented results demonstrate the effectiveness of the algorithm to investigate the deformation field in active volcanic areas and the potential of the DInSAR methodologies within routine surveillance scenario

    Modeling of the acute toxicity of benzene derivatives by complementary QSAR methods

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    A data set containing acute toxicity values (96-h LC50) of 69 substituted benzenes for fathead minnow (Pimephales promelas) was investigated with two Quantitative Structure- Activity Relationship (QSAR) models, either using or not using molecular descriptors, respectively. Recursive Neural Networks (RNN) derive a QSAR by direct treatment of the molecular structure, described through an appropriate graphical tool (variable-size labeled rooted ordered trees) by defining suitable representation rules. The input trees are encoded by an adaptive process able to learn, by tuning its free parameters, from a given set of structureactivity training examples. Owing to the use of a flexible encoding approach, the model is target invariant and does not need a priori definition of molecular descriptors. The results obtained in this study were analyzed together with those of a model based on molecular descriptors, i.e. a Multiple Linear Regression (MLR) model using CROatian MultiRegression selection of descriptors (CROMRsel). The comparison revealed interesting similarities that could lead to the development of a combined approach, exploiting the complementary characteristics of the two approaches

    The VELISAR initiative for the measurement of ground velocity in italian seismogenic areas

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    VELISAR (Ground VELocity in Italian Seismogenic Areas) is a scientific research initiative aimed at producing a map of the ground deformation over most of the seismogenic areas of Italy, using the space-based technique of multitemporal Synthetic Aperture Radar Interferometry (InSAR). The ground velocities derived from InSAR data will be validated by means of ground based data obtained from GPS, optical leveling, seismological and neotectonic studies. The scope of the project is to produce a high-resolution ground deformation dataset useful to model the seismic cycle of strain accumulation and release at the scale of the single faults. The main objective of VELISAR is to produce maps of ground velocity with the following characteristics: - A ground resolution better than 100 m. - Average uncertainty of LoS velocity measurements smaller than 2 mm/yr . - Temporal coverage of at least 7 years. - Retrieval of East and Up components from ascending and descending LoS. VELISAR will exploit the potential of the long time series (1992-2000) of ERS InSAR data maintained in the ESA archives; over 4000 ERS images will have to be processed to accomplish its objectives. Presently, two InSAR techniques for the measurement of slow ground deformation are used in VELISAR: the Permanent Scatterers (PS) technique developed by the Politecnico of Milano (POLIMI), and the Small Baseline Subset (SBAS) technique, developed by the Institute for Remote Sensing of Environment (IREA-CNR), in Napoli. The PS technique is applied by TRE preferably over areas characterised by diffuse temporal decorrelation due to, for instance, erodible lithologies, agricultural land use and strong vegetation cover. In these areas we expect to obtain good temporal coherence mainly on sparse point scatterers. The SBAS technique is applied by IREA and INGV mostly over areas where limited temporal decorrelation is expected: urban areas, scarcely vegetated areas. The ground resolution at which these data are originally processed is 80 m. An important goal of the VELISAR initiative is to disseminate the information on the InSAR-derived ground velocity measurements, to the scientific community and to the public in general. Such goal is accomplished through a dedicated web site, where the velocity maps of the italian seismogenic areas will be progressively published. We will present the initiative, its scope and objectives, the technical details and the data processing strategies, and some examples of ground velocity maps.PublishedVienna, Austriaope

    FIFTEEN YEARS OF ERS AND ENVISAT DInSAR OBSERVATIONS AT MT. ETNA (ITALY) BY USING THE SBAS APPROACH

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    We exploited the Small BAseline Subset (SBAS) technique and computed ground displacement maps and time series by inverting 283 interferograms generated from the ascending and 289 from the descending orbits to reveal Mt. Etna surface deformation from 1992 to 2006. Our analysis shows that the volcano experienced magmatic inflation/deflation and radial spreading of the west, south and east flanks. In particular, the summit area vertical deformation inverted its sign after 2000 and clearly shows a deflation effect related to the 2001 and 2002 eruptive and seismic events. On the contrary, the horizontal signals revealed on the eastern and western flanks present significant and consistent motions toward east and west, respectively, during the investigated interval. Overall, the presented results show the complex and articulated deformation behavior of Mt. Etna and remark the possible coexistence of both gravity and magma forcing

    The 2004–2006 uplift episode at Campi Flegrei caldera (Italy): Constraints from SBAS-DInSAR ENVISAT data and Bayesian source inference

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    We investigate the 2004–2006 uplift phase of Campi Flegrei caldera (Italy) by exploiting the archive of ascending and descending ENVISAT SAR data acquired from November 2002 to November 2006. The SBAS-DInSAR technique is applied to generate displacement mean velocity maps and time series. An appropriate post-processing step is subsequently applied to map the areas whose temporal deformation behavior is correlated with that of the maximum uplift zone. Our results show that the deformation also extends outside the volcanological limits of the Neapolitan Yellow Tuff caldera, without significant discontinuities. The DInSAR data are inverted by considering a finite spheroid and an isotropic pointsource. The inversion results suggest that the new uplift is characterized by a source location similar to the previous small uplift event of 2000 and to the long term subsidence of the 1990’s. In particular, the source is located at a depth of about 3.2 km and very close to the city of Pozzuoli (about 800 m offshore, to the SW); the associated volume variation is about 1.1 106 m3/year.PublishedL073081.10. TTC - TelerilevamentoJCR Journalreserve

    Developing cardiac and skeletal muscle share fast-skeletal myosin heavy chain and cardiac troponin-I expression

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    Skeletal muscle derived stem cells (MDSCs) transplanted into injured myocardium can differentiate into fast skeletal muscle specific myosin heavy chain (sk-fMHC) and cardiac specific troponin-I (cTn-I) positive cells sustaining recipient myocardial function. We have recently found that MDSCs differentiate into a cardiomyocyte phenotype within a three-dimensional gel bioreactor. It is generally accepted that terminally differentiated myocardium or skeletal muscle only express cTn-I or sk-fMHC, respectively. Studies have shown the presence of non-cardiac muscle proteins in the developing myocardium or cardiac proteins in pathological skeletal muscle. In the current study, we tested the hypothesis that normal developing myocardium and skeletal muscle transiently share both sk-fMHC and cTn-I proteins. Immunohistochemistry, western blot, and RT-PCR analyses were carried out in embryonic day 13 (ED13) and 20 (ED20), neonatal day 0 (ND0) and 4 (ND4), postnatal day 10 (PND10), and 8 week-old adult female Lewis rat ventricular myocardium and gastrocnemius muscle. Confocal laser microscopy revealed that sk-fMHC was expressed as a typical striated muscle pattern within ED13 ventricular myocardium, and the striated sk-fMHC expression was lost by ND4 and became negative in adult myocardium. cTn-I was not expressed as a typical striated muscle pattern throughout the myocardium until PND10. Western blot and RT-PCR analyses revealed that gene and protein expression patterns of cardiac and skeletal muscle transcription factors and sk-fMHC within ventricular myocardium and skeletal muscle were similar at ED20, and the expression patterns became cardiac or skeletal muscle specific during postnatal development. These findings provide new insight into cardiac muscle development and highlight previously unknown common developmental features of cardiac and skeletal muscle. © 2012 Clause et al

    Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data

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    We investigate a large geodetic data set of interferometric synthetic aperture radar (InSAR)and GPS measurements to determine the source parameters for the three main shocks of the 2016Central Italy earthquake sequence on 24 August and 26 and 30 October (Mw6.1, 5.9, and 6.5,respectively). Our preferred model is consistent with the activation of four main coseismic asperitiesbelonging to the SW dipping normal fault system associated with the Mount Gorzano-Mount Vettore-Mount Bove alignment. Additional slip, equivalent to aMw~ 6.1–6.2 earthquake, on a secondary (1) NEdipping antithetic fault and/or (2) on a WNW dipping low-angle fault in the hanging wall of the mainsystem is required to better reproduce the complex deformation pattern associated with the greatestseismic event (theMw6.5 earthquake). The recognition of ancillary faults involved in the sequencesuggests a complex interaction in the activated crustal volume between the main normal faults and thesecondary structures and a partitioning of strain releas
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