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Odermatt D.,University of Zürich | 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.

Minardo A.,The Second University of Naples | Bernini R.,CNR Institute for Electromagnetic Sensing of the Environment | Zeni L.,The Second University of Naples
Optics Express | Year: 2011

A numerical analysis of conventional and differential pulse-width pair Brillouin optical time domain analysis systems is reported. The tests are focused on determining the performance of these systems especially in terms of spatial resolution, as a function of the pulse characteristics. A new definition of spatial resolution is given, based on analysis of the shape of the Brillouin gain spectrum. The influence of the rise/fall time of the pulse light to the spatial resolution is also studied. © 2011 Optical Society of America.

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.

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.

Persichetti G.,CNR Institute for Electromagnetic Sensing of the Environment | Gesta G.,CNR Institute for Electromagnetic Sensing of the Environment | Bernini R.,CNR Institute for Electromagnetic Sensing of the Environment
Optics Express | Year: 2013

A novel spectroscopic sensor based on an optofluidic liquid jet waveguide is presented. In this device, a liquid jet waveguide is generated with the solution under analysis. This stream, exploiting total internal reflection, acts as an optical waveguide confining the autofluorescence light produced by chemical or biological samples when opportunely excited. Using a self-aligned configuration, the liquid jet is directly coupled with a multimode optical fiber collecting the fluorescence towards the detection system. Experimental measurements have been performed using an UV excitation source on water solutions containing representative water pollutants as aromatic hydrocarbons or bacteria showing very low limit of detection. © 2013 Optical Society of America.

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.

Fornaro G.,CNR Institute for Electromagnetic Sensing of the Environment | Reale D.,CNR Institute for Electromagnetic Sensing of the Environment | Verde S.,CNR Institute for Electromagnetic Sensing of the Environment
IEEE Geoscience and Remote Sensing Letters | Year: 2013

The new generation of synthetic aperture radar (SAR) sensors is providing images with very high spatial resolution, improved up to the meter scale. Such a resolution increase allows more accurate monitoring capabilities by means of interferometric approaches. The use of higher frequency enhances the sensitivity of the system even to minute changes, such as thermal dilations. This phenomenon has an impact on the interferometric products, particularly on the deformation velocity maps, if not properly handled. Man-made structures, such as steel core bridges and specific buildings, may be very sensible to thermal dilation effects. By extending the multitemporal differential interferometry SAR processing chains, in our case based on the multidimensional imaging (MDI) approach, an additional parameter related to temperature differences at acquisition instants, the thermal coefficient, can be accurately estimated. This parameter provides interesting perspectives in application to infrastructure monitoring: It brings information about the thermal behavior of the imaged objects. In this letter, we investigate the thermal response of the Musmeci bridge (Potenza, Italy), by experimenting the extended MDI approach on a real TerraSAR-X data set. Results highlight the possibility of such a technique to obtain measurements of the motion that is highly correlated with temperature, thus providing useful information about the static structure of bridges. © 2012 IEEE.

Gennarelli G.,CNR Institute for Electromagnetic Sensing of the Environment | Soldovieri F.,CNR Institute for Electromagnetic Sensing of the Environment
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2015

Most algorithms commonly exploited for radar imaging are based on linear models that describe only direct scattering events from the targets in the investigated scene. This assumption is rarely verified in practical scenarios where the objects to be imaged interact with each other and with surrounding environment producing undesired multipath signals. These signals manifest in radar images as "ghosts" that usually impair the reliable identification of the targets. The recent literature in the field is attempting to provide suitable techniques for multipath suppression from one side and from the other side is focusing on the exploitation of the additional information conveyed by multipath to improve target detection and localization. This work addresses the first problem with a specific focus on multipath ghosts caused by target-to-target interactions. In particular, the study is performed with regard to metallic scatterers by means of the linearized inverse scattering approach based on the physical optics (PO) approximation. A simple model is proposed in the case of point-like targets to gain insight into the ghosts problem so as to devise possible measurement and processing strategies for their mitigation. Finally, the effectiveness of these methods is assessed by reconstruction results obtained from full-wave synthetic data. © 2008-2012 IEEE.

Testa G.,CNR Institute for Electromagnetic Sensing of the Environment | Bernini R.,CNR Institute for Electromagnetic Sensing of the Environment
Journal of Lightwave Technology | Year: 2011

Slot waveguides based on TiO$ 2 nanowires are numerically analyzed in the visible spectrum. The modal properties and the sensing capabilities of a conventional slot waveguide are investigated at an operating wavelength of 635 nm. Furthermore, a novel slot waveguide configuration called Layer-slot (L-slot) is proposed and discussed. The numerical results show that L-slot waveguides permit to achieve field confinement and sensing properties with values comparable with conventional slot waveguide, but with a strongly simplified fabrication process. © 2006 IEEE.

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.

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