392 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

    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

    Nanocomposite field effect transistors based on zinc oxide/polymer blends

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    The authors have examined the field effect behavior of nanocomposite field effect transistors containing ZnO (zinc oxide) tetrapods or nanocrystals dispersed in a polymer matrix of poly[2-methoxy,5-(2-ethylhexyloxy)-1,4- phenylenevinylene] (MEH-PPV). The electrical characteristics of ZnO tetrapods/MEH-PPV composite devices exhibit an increase in hole mobility up to three orders of magnitude higher than the polymer MEH-PPV device. © 2007 American Institute of Physics.published_or_final_versio

    A time-temperature integrator based on fluorescent and polymorphic compounds

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    Despite the variety of functional properties of molecular materials, which make them of interest for a number of technologies, their tendency to form inhomogeneous aggregates in thin films and to self-organize in polymorphs are considered drawbacks for practical applications. Here, we report on the use of polymorphic molecular fluorescent thin films as time temperature integrators, a class of devices that monitor the thermal history of a product. The device is fabricated by patterning the fluorescent model compound thieno(bis)imide-oligothiophene. The fluorescence colour of the pattern changes as a consequence of an irreversible phase variation driven by temperature, and reveals the temperature at which the pattern was exposed. The experimental results are quantitatively analysed in the range 20–200°C and interpreted considering a polymorph recrystallization in the thin film. Noteworthy, the reported method is of general validity and can be extended to every compound featuring irreversible temperature-dependent change of fluorescence

    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

    “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

    Caratterizzazione dell’ambiente marino dei Campi Flegrei. Risultati preliminari della campagna oceanografica RICAMAR 2013

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    The caldera of the Phlegraean Fields (also known as Campi Flegrei) is one of the most dangerous and populated volcanic area in the world, covering an area that comprises the western part of Naples and the Gulf of Pozzuoli. The main peculiarity of current volcanic activity is the gradual and periodic lift (positive or negative) of part of the Earth\u27s surface (bradyseism) combined, only during the positive phase, with a strong sismicity and surficial hydrotermal activity. Deformative models, calibrated using land-based measurements, highlighted the Gulf of Pozzuoli as the area with the largest deformation. Although the network of monitoring sensors on land is well developed and structured, there is a lack of sensing systems for the marine deformation. The activities of RIlievi per la Caratterizzazione dell’Ambiente MARino nel Golfo di Pozzuoli 2013 (RICAMAR2013) project - sinergically conducted by the Italian Navy\u27s Survey Vessel Ammiraglio Magnaghi , the Italian Hydrographic Office (IIM) and the Istituto Nazionale di Geofisica e Vulcanologia (INGV)- were targeted to fulfill this gap. In fact, the creation of marine observatories about the caldera\u27s phenomena will be based on the data collected during these bathymetric, magnetometric, stratigrafic and hydrologic surveys

    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

    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

    Multidisciplinary Investigations at Panarea (Aeolian Islands) after the Exhalative Crisis of 2002

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    Panarea and surrounding Islets form a volcanic edifice, that is part of the Eastern sector of the Aeolian Arc, Southern Tyrrhenian Sea. It is now considered inactive, since last documented activity is 20 Ka old. However, on 2002-11-03, gas started to flow violently from the seafloor in an area E of the Island, mainly along NE and NW structural lineaments, and lasting up to 2003-2004 with a consistent flux, orders of magnitude larger that ’steady-state’ fumarolic activity documented there in historical times. On the same period a strong effusive activity of Stromboli (10 NM to NNE) was present. Since then, several investigations have been conducted at sea and on land, with the aim of focusing on the problem of effusive activity at sea, mainly in the light of volcanic surveillance and risk. Among these investigations, some of which have been repeated over years, we present and discuss some data and results from: (a)visual inspection and sampling by divers and ROV, (b)GPS networks and mapping by multibeam and LIDAR, (c) oceanographical measurements by current meters and CTD, and water flux and dynamics measurements, (d)magnetic and gravimetric surveys, (e) multichannel reflection Seismic with OBS and land station networks. Data were used for compilation of high resolution bathymetric, magnetic and gravimetric maps, including the emerged and submerged portions of the edifice
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