263 research outputs found

    The first ultra-high resolution Digital Terrain Model of the shallow-water sector around Lipari Island (Aeolian Islands, Italy)

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    Very high resolution bathymetric map obtained through multibeam echosounders data are crucial to generate accurate Digital Terrain Models from which the morphological setting of active volcanic areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the island of Lipari, the largest and the most densely populated of the Aeolian Islands (southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultrahigh resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters

    Multibeam bathymetry of Lipari island

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    Very high resolution bathymetric map obtained through multibeam echo-sounders data are crucial to generate accurate Digital Elevation Terrain Models from which the morphological setting of active volcanic areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the Island of Lipari, the largest and the most densely populated of the Aeolian islands (Southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultra-high resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters

    The size of electron-hole pairs in pi conjugated systems

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    We have performed momentum dependent electron energy-loss studies of the electronic excitations in sexithiophene and compared the results to those from parent oligomers. Our experiment probes the dynamic structure factor S(q,omega)and we show that the momentum dependent intensity variation of the excitations observed can be used to extract the size of the electron-hole pair created in the excitation process. The extension of the electron-hole pairs along the molecules is comparable to the length of the molecules and thus maybe only limited by structural constraints. Consequently, the primary intramolecular electron-hole pairs are relatively weakly bound. We find no evidence for the formation of excitations localized on single thiophene units.Comment: RevTex, 3 figures, to appear in Physical Review Letter

    “ALLA SCOPERTA dei TESORI del MARE” - Scienza e Tecnologia, Memoria Popolare e Identità Culturale di una città della costa ligure

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    “Il dovere degli scienziati non è quello di educare il pubblico, ma piuttosto di interagire con esso. Il pubblico è la vera forza trainante dietro decisioni con conseguenze sociali, e deve essere coinvolto su base paritaria nei dibattiti inerenti queste decisioni” . La comunicazione scientifica e tecnologica fra scienza e società, da anni, non è più un mero scambio di informazioni e risultati (spesso fra determinate élite), ma è diventata il veicolo privilegiato per insegnare, formare ed ispirare un pubblico sempre più ampio. Ma non si parla solo di trasmissione uni-direzionale: il dibattito fra scienza, tecnologia e società (amministratori locali, politici, imprenditori, giornalisti, studenti e semplici cittadini) sta guadagnando una partecipazione di interlocutori sempre più numerosi e preparati su temi dalle complesse caratteristiche ed implicazioni (etiche, sociali, economiche, politiche). Questo è in parte dovuto ai cambiamenti avvenuti negli ultimi anni nella scienza (e all’impatto che essa sta avendo in molti ambiti della vita sociale. Tali cambiamenti stanno determinando nuove forme di comunicazione scientifica e cooperazione con la società e l’aumento, nell’ultimo decennio, di iniziative e percorsi di formazione, spesso organizzati dalle stesse istituzioni scientifiche. Uno dei risultati più tangibili della cambiata interazione fra scienza e società è la nuova generazione di ricercatori-comunicatori, dotati di una maggiore abilità nel comunicare la scienza in modo efficace e ad un pubblico più ampio e diversificato. In questo contesto diventa importante capire l’efficacia di ogni azione di comunicazione scientifica, impostando uno studio che analizzi, volta per volta, i punti di successo e le criticità emerse nei due comparti causa-effetto. Causa – gli elementi di base della comunicazione scientifica e tecnologica:  i valori sociali e culturali di riferimento (ad es. protezione ambientale, sicurezza, salute); - i contenuti (formato di presentazione, tematiche scelte); - i canali usati (web, social networks, stampa cartacea etc.); - i modelli di relazione con il pubblico (scienza vs pubblico, peer education). Effetto - la risposta della società:  diretta (affluenza; questionari di gradimento)  indiretta (visualizzazioni web; like se tweet dei social network). Questo lavoro presenta una relazione illustrativa (per la prima volta sul territorio della Spezia) dell’efficacia di un evento specifico inserito all’interno di una manifestazione di portata locale, la “Festa della Marineria 2013 ”, destinato al grande pubblico e caratterizzato da diverse attività (tra le quali quelle di tipo ludico-educativo) concepite con l’obiettivo di puntare l’attenzione sui ‘tesori’ scientifici e culturali di una ‘Città di Mare’qual'è La Spezia

    Genesis of oceanic oxide gabbros and gabbronorites during reactive melt migration at transform walls (Doldrums Megatransform System; 7-8°N Mid-Atlantic Ridge)

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    The Doldrums Megatransform System (~7-8°N, Mid-Atlantic Ridge) shows a complex architecture including four intra-transform ridge segments bounded by five active transform faults. Lower crustal rocks are exposed along the Doldrums and Vernadsky transform walls that bound the northernmost intra-transform ridge segment. The recovered gabbros are characterized by variably evolved chemical compositions, ranging from olivine gabbros to gabbronorites and oxide gabbros, and lack the most primitive gabbroic endmembers (troctolites, dunites). Notably, the numerous recovered gabbronorites show up to 20 vol% of coarse-grained orthopyroxene. Although covariations in mineral and bulk-rock chemical compositions of the olivine and oxide gabbros define trends of crystallization from a common parental melt, the gabbronorites show elevated light over heavy rare earth elements (LREE/HREE) ratios in both bulk-rock and mineral compositions. These features are not consistent with a petrological evolution driven solely by fractional crystallization, which cannot produce the preferential enrichments in highly incompatible elements documented in the orthopyroxene-bearing lithologies. We suggest that gabbronorites crystallized from evolved melts percolating and partly assimilating a pre-existing olivine gabbro matrix. Saturation in orthopyroxene and selective enrichments in LREE relative to M-HREE are both triggered by an increase in assimilated crystal mass, which ranges from negligible in the oxide-gabbros to abundant in the gabbronorites. This melt-rock reaction process has been related to lateral melt migration beneath ridge-transform intersections, where variably evolved melts injected from the peripheral parts of the melting region towards the transform zone may interact with a gabbroic crystal mush to form abundant oxide-bearing gabbronoritic associations

    The tsunamigenic potential of landslide-generated tsunamis on the Vavilov seamount

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    The investigation of submarine volcanoes and the tsunamigenic potential of possible movements on their flanks is arduous. In most cases, the lack of specific information about the eruptions’ history and their consequences does not allow a comprehensive analysis in terms of hazard. Nevertheless, useful clues on the possible occurrence of mass movements on seamounts can be obtained from a series of research fields. These account for morphological studies, observations of hydrothermal activity, collection of geophysical data (for example, detailed DEM, seismic profiles, magnetic data), etc. In this context, this study presents new bathymetric data of the Vavilov submarine volcano (Tyrrhenian Sea, Italy) and a detailed morphological analysis of the structure. The latter allows the identification of zones potentially prone to mass movements and the development of numerical scenarios to investigate the tsunami potential associated to these movements on the Vavilov flanks. Results prove that the waves generated by the mass displacements in the proposed scenarios (involving sliding volumes between 0.32 km3 and 1.7 km3) reach maximum values in the order of centimetres, not considering dispersive effects. Eventually, a scenario involving the partial collapse of the west flank of the Vavilov Seamount is simulated, although the occurrence of such an event in the past is still debated due to the uncertainties related to the origin and development of the volcano dome. In this scenario, water elevation as high as 10 m are found in large portions of the Tyrrhenian coasts: waves are large enough to emplace sizeable tsunami deposits onshore, that could have been preserved until today in some specific stretches of the coast and could be detected by a finalised geological search. This study belongs to a series of works devoted to the submarine structures of the Tyrrhenian Sea aiming to disclose the tsunamigenic potential of submarine mass movements on their flanks

    Architecture-based testing and system validation: Workshop summary

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    This paper summarizes the workshop on Architecture-Based Testing and System Validation which was organized in conjunction with the 9th Working IEEE/IFIP Conference on Software Architecture. The main goal of the workshop was to bring together researchers and practitioners both from the architecture design and software testing community to enable architecture-based software testing. © 2011 IEEE

    Ground state properties of ferromagnetic metal/conjugated polymer interfaces

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    We theoretically investigate the ground state properties of ferromagnetic metal/conjugated polymer interfaces. The work is partially motivated by recent experiments in which injection of spin polarized electrons from ferromagnetic contacts into thin films of conjugated polymers was reported. We use a one-dimensional nondegenerate Su-Schrieffer-Heeger (SSH) Hamiltonian to describe the conjugated polymer and one-dimensional tight-binding models to describe the ferromagnetic metal. We consider both a model for a conventional ferromagnetic metal, in which there are no explicit structural degrees of freedom, and a model for a half-metallic ferromagnetic colossal magnetoresistance (CMR) oxide which has explicit structural degrees of freedom. The Fermi energy of the magnetic metallic contact is adjusted to control the degree of electron transfer into the polymer. We investigate electron charge and spin transfer from the ferromagnetic metal to the organic polymer, and structural relaxation near the interface. Bipolarons are the lowest energy charge state in the bulk polymer for the nondegenerate SSH model Hamiltonian. As a result electrons (or holes) transferred into the bulk of the polymer form spinless bipolarons. However, there can be spin density in the polymer localized near the interface.Comment: 7 figure

    Development of Quantum Dot (QD) Based Color Converters for Multicolor Display.

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    Many displays involve the use of color conversion layers. QDs are attractive candidates as color converters because of their easy processability, tuneable optical properties, high photoluminescence quantum yield, and good stability. Here, we show that emissive QDs with narrow emission range can be made in-situ in a polymer matrix, with properties useful for color conversion. This was achieved by blending the blue-emitting pyridine based polymer with a cadmium selenide precursor and baking their films at different temperatures. To achieve efficient color conversion, blend ratio and baking temperature/time were varied. We found that thermal decomposition of the precursor leads to highly emissive QDs whose final size and emission can be controlled using baking temperature/time. The formation of the QDs inside the polymer matrix was confirmed through morphological studies using atomic force microscopy (AFM) and transmission electron microscopy (TEM). Hence, our approach provides a cost-effective route to making highly emissive color converters for multi-color displays

    Shear strength characterization of metal-elastomer bonded joints

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