791 research outputs found

    Bedding control on landslides: A methodological approach for computer-aided mapping analysis

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    Litho-structural control on the spatial and temporal evolution of landslides is one of the major typical aspects on slopes constituted of structurally complex sequences. Mainly focused on instabilities of the earth flow type, a semi-quantitative analysis has been developed with the purpose of identifying and characterizing litho-structural control exerted by bedding on slopes and its effects on landsliding. In quantitative terms, a technique for azimuth data interpolation, Non-continuous Azimuth Distribution Methodological Approach (NADIA), is presented by means of a GIS software application. In addition, processed by NADIA, two indexes have been determined: (i) Δ, aimed at defining the relationship between the orientation of geological bedding planes and slope aspect, and (ii) C, which recognizes localized slope sectors in which the stony component of structurally complex formations is abundant and therefore operates an evolutive control of landslide masses. Furthermore, some Litho-Structural Models (LSMs) of slopes are proposed aiming at characterizing recurrent forms of structural control in the source, channel and deposition areas of gravitational movements. In order to elaborate evolutive models controlling landslide scenarios, LSMs were qualitatively related and compared with Δ and C; quantitative indexes. The methodological procedure has been applied to a lithostructurally complex area of Southern Italy where data about azimuth measurements and landslide mapping were known. It was found that the proposed methodology enables the recognition of typical control conditions on landslides in relation to the LSMs. Different control patterns on landslide shape and on style and distribution of the activity resulted for each LSM. This provides the possibility for first-order identification to be made of the spatial evolution of landslide bodies. © Author(s) 2011

    Channel Selection for Optimal EEG Measurement in Motor Imagery-Based Brain-Computer Interfaces

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    A method for selecting electroencephalographic (EEG) signals in motor imagery-based brain-computer interfaces (MI-BCI) is proposed for enhancing the online interoperability and portability of BCI systems, as well as user comfort. The attempt is also to reduce variability and noise of MI-BCI, which could be affected by a large number of EEG channels. The relation between selected channels and MI-BCI performance is therefore analyzed. The proposed method is able to select acquisition channels common to all subjects, while achieving a performance compatible with the use of all the channels. Results are reported with reference to a standard benchmark dataset, the BCI competition IV dataset 2a. They prove that a performance compatible with the best state-of-the-art approaches can be achieved, while adopting a significantly smaller number of channels, both in two and in four tasks classification. In particular, classification accuracy is about 77-83% in binary classification with down to 6 EEG channels, and above 60% for the four-classes case when 10 channels are employed. This gives a contribution in optimizing the EEG measurement while developing non-invasive and wearable MI-based brain-computer interfaces

    Quantitative dominances of taxa structuring the macrozoobenthic communities living in different coastal habitats.

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    The aim of this study was to quantify the dominance of macrozoobenthic taxa structuring the benthic assemblages associated to 6 coastal habitats, which occur from the mesolittoral to the circalittoral zone of the Campania coast. Crustaceans, polychaetes and molluscs were the main taxonomic groups structuring all the benthic assemblages, representing an average of 89.20% of the total taxa. However, each habitat showed the dominance of only one peculiar taxon

    Red coral (Corallium rubrum) populations and coralligenous characterization within "Regno di Nettuno MPA" (Tyrrhenian Sea, Italy)

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    Red coral is one of the most important species belonging to the coralligenous habitats, being a structuring organism and highly sensitive to human pressure. The presence of red coral populations is historically well documented along the Campania coast (Tyrrhenian Sea), and, due to its high economic value, it has been commercially overharvested since ancient times. Red coral populations along several cliffs on the "Regno di Nettuno" MPA of the Gulf of Naples were investigated using ROV-imaging techniques. Coralligenous habitats were characterized in terms of percent cover and number of morphological groups. Pizzaco site showed the richest and most diverse community. Density of red coral colonies was calculated and compared with morphometric parameters. Results show an inversely correlated trend between colonies density and their size. Finally, fishing pressure was estimated through frequency of lost fishing gears, and S. Angelo site resulted the most stressed one. Anthropic stress plays a key role in the degradation of coralligenous habitats and the dramatic reduction of red coral populations recorded in recent years allows to suspect a more extensive degradation of the entire community. An assessment of the distribution and state of the populations can provide useful information to take measures for a better MPAs management

    Non-vascular interventional procedures: effective dose to patient and equivalent dose to abdominal organs by means of dicom images and Monte Carlo simulation

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    This study evaluates X-ray exposure in patient undergoing abdominal extra-vascular interventional procedures by means of Digital Imaging and COmmunications in Medicine (DICOM) image headers and Monte Carlo simulation. The main aim was to assess the effective and equivalent doses, under the hypothesis of their correlation with the dose area product (DAP) measured during each examination. This allows to collect dosimetric information about each patient and to evaluate associated risks without resorting to in vivo dosimetry. The dose calculation was performed in 79 procedures through the Monte Carlo simulator PCXMC (A PC-based Monte Carlo program for calculating patient doses in medical X-ray examinations), by using the real geometrical and dosimetric irradiation conditions, automatically extracted from DICOM headers. The DAP measurements were also validated by using thermoluminescent dosimeters on an anthropomorphic phantom. The expected linear correlation between effective doses and DAP was confirmed with an R(2) of 0.974. Moreover, in order to easily calculate patient doses, conversion coefficients that relate equivalent doses to measurable quantities, such as DAP, were obtained

    Powerful high energy emission of the remarkable BL Lac object S5 0716+714

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    BL Lac objects of the intermediate subclass (IBLs) are known to emit a substantial fraction of their power in the energy range 0.1--10 GeV. Detecting gamma-ray emission from such sources provides therefore a direct probe of the emission mechanisms and of the underlying powerhouse. The AGILE gamma-ray satellite detected the remarkable IBL S5 0716+714 (z \simeq 0.3) during a high state in the period from 2007 September - October, marked by two very intense flares reaching peak fluxes of 200\times10^{-8} ph / cm^2 s above 100 MeV, with simultaneous optical and X-ray observations. We present here a theoretical model for the two major flares and discuss the overall energetics of the source. We conclude that 0716+714 is among the brightest BL Lac's ever detected at gamma-ray energies. Because of its high power and lack of signs for ongoing accretion or surrounding gas, the source is an ideal candidate to test the maximal power extractable from a rotating supermassive black hole via the pure Blandford-Znajek (BZ) mechanism. We find that during the 2007 gamma-ray flares our source approached or just exceeded the upper limit set by BZ for a black hole of mass 10^9 M_sunComment: 12 pages, 3 figure
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