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Manconi A.,CNR Research Institute for Geo-hydrological Protection | Casu F.,CNR Institute for Electromagnetic Sensing of the Environment
Geophysical Research Letters | Year: 2012

We study the impact of jointly analyzing the phase and amplitude information of a SAR dataset on the interpretation of the surface displacement over time in areas characterized by large dynamics. In particular, we compute the ground displacement time series over Fernandina and Sierra Negra calderas (Galápagos islands), by applying the Small BAseline Subset (SBAS) and the Pixel Offset (PO)-SBAS techniques to 25 ENVISAT SAR images acquired between 2003 and 2007, when both volcanoes experienced catastrophic eruptions. By merging the SBAS and PO-SBAS time series results the spatial density of measurements increased substantially. In addition, the joint analysis of the time series allows us to better constrain the temporal evolution of the magmatic source volume changes. Our results show that the joint use of the SBAS and PO-SBAS approaches may help for a more correct evaluation of large deformation affecting the Earth's surface caused by eruptions, earthquakes, and landslide phenomena. © 2012. American Geophysical Union. Source

Villa P.,CNR Institute for Electromagnetic Sensing of the Environment
Landscape and Urban Planning | Year: 2012

Remote sensing based on mid-resolution multi-spectral data has proven a powerful tool in urban areas study. This work introduces a novel methodology based on spectral indices ratios for mapping urban changes in terms of impervious surface expansion. At the methodological core, the Soil and Vegetation Index (SVI), a spectral index aimed at discriminating urban from non-urban land cover, has been utilized over Landsat TM-ETM+ satellite data. As a case study, the approach was applied to a multi-temporal dataset, with the aim of mapping the urban growth of Milan, Italy, during 20 years (1984-2003). The multi-step processing framework is composed of: SVI values derivation and normalization, multi-temporal SVI ratios thresholding for identifying urban growth area, and multiscale segmentation of urban change maps produced. Results analysis showed the feasibility of the approach and reliability of urban change maps derived, which reached a value of Overall Accuracy up to 80%, while multi-scale assessment of results revealed the 25 pixels segmentation scale as the optimal one for urban change detection using Landsat data over the study area. © 2012 Elsevier B.V. Source

Odermatt D.,University of Zurich | Giardino C.,CNR Institute for Electromagnetic Sensing of the Environment | Heege T.,EOMAP GmbH
Remote Sensing of Environment | Year: 2010

Semi-analytical remote sensing applications for eutrophic waters are not applicable to oligo- and mesotrophic lakes in the perialpine area, since they are insensitive to chlorophyll concentration variations between 1 and 10 mg/m3. The neural network based Case-2-Regional algorithm for MERIS was developed to fill this gap, along with the ICOL adjacency effect correction algorithm. The algorithms are applied to a collection of 239 satellite images from 2003-2008, and the results are compared to experimental and official water quality data collected in six perialpine lakes in the same period. It is shown that remote sensing estimates can provide an adequate supplementary data source to in situ data series of the top 5 m water layer, provided that a sufficient number of matchups for a site specific maximum temporal offset are available. © 2009 Elsevier Inc. All rights reserved. Source

Zeni O.,CNR Institute for Electromagnetic Sensing of the Environment
Methods in molecular biology (Clifton, N.J.) | Year: 2010

The single-cell gel electrophoresis (SCGE) or comet assay is a simple and sensitive method for quantitatively measuring DNA breakage and repair in individual cells. It can be applied to proliferating and non-proliferating cells and cells of those tissues, which are the first contact sites for mutagenic/carcinogenic substances. In this technique, cells are embedded in agarose, lysed, subjected to electrophoresis, and stained with a fluorescent DNA-binding dye. Cells with increased DNA damage display increased DNA migration from the nucleus toward the anode, which resembles the shape of a comet. The migration is observed by fluorescence microscopy after staining with a fluorescent DNA-binding dye, and the intensity of the comet tail reflects the number of DNA breaks. The assay is performed in almost all eukaryotic cells and has applications in many fields, including genetic toxicology, biomonitoring, ecotoxicology, medical, and nutritional research. The assay is a very sensitive tool to investigate the effect of carbon nanotubes on DNA of human cells in vitro. This chapter describes a procedure to perform the comet assay, in its alkaline version, on cell cultures treated with carbon nanotubes. Source

Gennarelli G.,CNR Institute for Electromagnetic Sensing of the Environment | Soldovieri F.,CNR Institute for Electromagnetic Sensing of the Environment
IEEE Transactions on Geoscience and Remote Sensing | Year: 2014

We address the problem of imaging targets located behind an inhomogeneous wall made with cinderblocks. The problem, which has relevance in through-wall-imaging applications, is characterized by the presence of multipath propagation phenomena usually producing artifacts and distortions in the retrieved images, if not suitably accounted for in the scattering model. The strategy here adopted to mitigate this issue is to employ a linearized scattering model based on the Born approximation, where the kernel of the relevant integral equation is evaluated numerically by means of the finite-difference time-domain method. In this way, the complexity of the background scenario is accurately taken into account. The inversion is successfully performed by the truncated singular value decomposition algorithm so as to regularize the inverse problem. The achievable imaging capabilities are analyzed in terms of resolution limits, and most notably, resolution can be effectively enhanced, owing to multipath exploitation. Numerical tests based on synthetic data are reported to assess the reconstruction performance in the case of canonical objects. © 1980-2012 IEEE. Source

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