199 research outputs found

    Notes on the limits to knowledge explored with Darwinian logic

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    Observations on the Enamel of Odontomas

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    The morphological study of odontomas provides an alternative model for observing the formation of dental tissues, since different maturing stages are present simultaneously. Investigations were performed on decalcified samples (using light microscopy and transmission electron microscopy) and on undecalcified samples of complex odontoma enamel (using transmission electron microscopy). Simultaneous presence of prismatic enamel at various maturing stages with different structural characteristics was observed. Such enamel was sometimes associated with layers of ameloblastic cells with characteristics of cells in functional activity. In other sites, the enamel did not present a prismatic structure but it appeared as unstructured material clusters with abundant organic component. It was concluded that the theory according to which an ecto-mesenchymal inductive failure occurs in odontomas is not confirmed. The defect seen at the beginning of the differentiated and anomalous tissue maturation may be related to latest events in the development of the enamel organ. In this regard, it was concluded that such events involve the efficiency of the ameloblasts and the possible alterations in the organic matrix

    Preliminary results of P-wave and S-wave measurements by seismic dilatometer test (SPDMT) in Mirandola (Italy)

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    A trial seismic dilatometer-VP (SPDMT) has been recently developed to measure the compressional wave velocity VP, in addition to the shear wave velocity VS and to the DMT geotechnical parameters. The new SPDMT is the combination of the traditional mechanical flat dilatometer (DMT) with an appropriate seismic module placed above the DMT blade. The SPDMT module consist in a probe outfitted with two receivers for measuring the P-wave velocity, along with two receivers for measuring the S-wave velocity. The paper describes the SPDMT equipment, the test procedure and the interpretation of VP and VS measurements, together with some considerations on the potential geotechnical applications which can benefit from the contemporary measurement of the two propagation velocities. Finally, the paper illustrates preliminary results of P-wave and S-wave measurements by SPDMT compared to several cross-hole, down-hole and suspension logging data at the Mirandola test site (Italy), a soft alluvial site which was investigated within the InterPACIFIC (Intercomparison of methods for site parameter and velocity profile characterization) project

    Seismic Tomography Experiment at Italy's Stromboli Volcano

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    From 25 November to 2 December 2006, the first active seismic tomography experiment at Stromboli volcano was carried out with the cooperation of four Italian research institutions. Researchers on board the R/V Urania of the Italian National Council of Research (CNR), which was equipped with a battery of four 210- cubic- inch generated injection air guns (GI guns), fired more than 1500 offshore shots along profiles and rings around the volcano.DPC/INGV agreement 2004-2006Published269-2701.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani3.6. Fisica del vulcanismoN/A or not JCRreserve

    Particle-resolved lattice Boltzmann simulations of 3-dimensional active turbulence

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    Collective behaviour in suspensions of microswimmers is often dominated by the impact of long-ranged hydrodynamic interactions. These phenomena include active turbulence, where suspensions of pusher bacteria at sufficient densities exhibit large-scale, chaotic flows. To study this collective phenomenon, we use large-scale (up to N=3×106N=3\times 10^6) particle-resolved lattice Boltzmann simulations of model microswimmers described by extended stresslets. Such system sizes enable us to obtain quantitative information about both the transition to active turbulence and characteristic features of the turbulent state itself. In the dilute limit, we test analytical predictions for a number of static and dynamic properties against our simulation results. For higher swimmer densities, where swimmer-swimmer interactions become significant, we numerically show that the length- and timescales of the turbulent flows increase steeply near the predicted finite-system transition density

    The Stromboli geophysical experiment. Preliminary report on wide angle refraction seismics and morphobathymetry of Stromboli Island (Southern Tyrrhenian Sea, Italy) based on integrated offshore-onshore data acquisition (Cruise STR06 R/V URANIA)

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    Cruise STR06 on R/V Urania was performed in the framework of the ”INGV - DPC V2 - Monitoring and research activity at Stromboli and Panarea - Unit V2/03”, and resulted as a joint initiative between CNR (IAMC, Napoli and ISMAR, Bologna), INGV (Roma2, Osservatorio Vesuviano, Catania, Gibilmanna-CNT), University of Firenze and DPC, aiming to produce a seismic tomography of the Stromboli volcano, South Eastern Tyrrhenian Sea [Fig.1], and have insights into its 2-D structure and magma chambers. Cruise work plan was designed to extend at sea the existing Seismographic Network, complemented by several mobile stations, and to generate seismic shots by air-gun tuned array. 10 OBS were deployed around Stromboli, along the NE, SE and SW flanks of the volcano, according to (a) morphobathymetric analysis of available and newly produced DTMs, (b) modeling and (c) optimal lineaments with on-land recording stations. Seismic shots along radial and circle lines were obtained by a 4 GI-GUN 105+105 C.I. tuned array, while the absolute shot time was recorded at the resolution of ms. A request for ship time of R/V Uraniawas presented by IAMC, and a period of 7 days, including 2 day of transit was assigned to the project by CNR and scheduled for late November 2006. Cruise STR06 started in Naples 2006-11-27 and ended in Naples 2006-12-06. This paper reports the shipboard activities during the cruise STR06 on R/V Urania and some preliminary results regarding also the onshore activities carried out in order to perform the Stromboli geophysical experiment. A description of the ship, equipment and their usage is given thereinafter, along with details of the general settings, performances and some scientific and technical results.Istituto di Scienze Marine, ISMAR-CNR, BolognaPublished3.6. Fisica del vulcanismo1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attiveope

    The Stromboli geophysical experiment. Preliminary report on wide angle refraction seismics and morphobathymetry of Stromboli Island (Southern Tyrrhenian Sea, Italy) based on integrated offshore-onshore data acquisition (Cruise STR06 R/V URANIA)

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    Cruise STR06 on R/V Urania was performed in the framework of the ”INGV - DPC V2 - Monitoring and research activity at Stromboli and Panarea - Unit V2/03”, and resulted as a joint initiative between CNR (IAMC, Napoli and ISMAR, Bologna), INGV (Roma2, Osservatorio Vesuviano, Catania, Gibilmanna-CNT), University of Firenze and DPC, aiming to produce a seismic tomography of the Stromboli volcano, South Eastern Tyrrhenian Sea [Fig.1], and have insights into its 2-D structure and magma chambers. Cruise work plan was designed to extend at sea the existing Seismographic Network, complemented by several mobile stations, and to generate seismic shots by air-gun tuned array. 10 OBS were deployed around Stromboli, along the NE, SE and SW flanks of the volcano, according to (a) morphobathymetric analysis of available and newly produced DTMs, (b) modeling and (c) optimal lineaments with on-land recording stations. Seismic shots along radial and circle lines were obtained by a 4 GI-GUN 105+105 C.I. tuned array, while the absolute shot time was recorded at the resolution of ms. A request for ship time of R/V Uraniawas presented by IAMC, and a period of 7 days, including 2 day of transit was assigned to the project by CNR and scheduled for late November 2006. Cruise STR06 started in Naples 2006-11-27 and ended in Naples 2006-12-06. This paper reports the shipboard activities during the cruise STR06 on R/V Urania and some preliminary results regarding also the onshore activities carried out in order to perform the Stromboli geophysical experiment. A description of the ship, equipment and their usage is given thereinafter, along with details of the general settings, performances and some scientific and technical results

    The DREAMS experiment flown on the ExoMars 2016 mission for the study of Martian environment during the dust storm season

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    The DREAMS (Dust characterization, Risk assessment and Environment Analyser on the Martian Surface) instrument on Schiaparelli lander of ExoMars 2016 mission was an autonomous meteorological station designed to completely characterize the Martian atmosphere on surface, acquiring data not only on temperature, pressure, humidity, wind speed and its direction, but also on solar irradiance, dust opacity and atmospheric electrification; this comprehensive set of parameters would assist the quantification of risks and hazards for future manned exploration missions mainly related to the presence of airborne dust. Schiaparelli landing on Mars was in fact scheduled during the foreseen dust storm season (October 2016 in Meridiani Planum) allowing DREAMS to directly measure the characteristics of such extremely harsh environment. DREAMS instrument’s architecture was based on a modular design developing custom boards for analog and digital channel conditioning, power distribution, on board data handling and communication with the lander. The boards, connected through a common backbone, were hosted in a central electronic unit assembly and connected to the external sensors with dedicated harness. Designed with very limited mass and an optimized energy consumption, DREAMS was successfully tested to operate autonomously, relying on its own power supply, for at least two Martian days (sols) after landing on the planet. A total of three flight models were fully qualified before launch through an extensive test campaign comprising electrical and functional testing, EMC verification and mechanical and thermal vacuum cycling; furthermore following the requirements for planetary protection, contamination control activities and assay sampling were conducted before model delivery for final integration on spacecraft. During the six months cruise to Mars following the successful launch of ExoMars on 14th March 2016, periodic check outs were conducted to verify instrument health check and update mission timelines for operation. Elaboration of housekeeping data showed that the behaviour of the whole instrument was nominal during the whole cruise. Unfortunately DREAMS was not able to operate on the surface of Mars, due to the known guidance anomaly during the descent that caused Schiaparelli to crash at landing. The adverse sequence of events at 4 km altitude anyway triggered the transition of the lander in surface operative mode, commanding switch on the DREAMS instrument, which was therefore able to correctly power on and send back housekeeping data. This proved the nominal performance of all DREAMS hardware before touchdown demonstrating the highest TRL of the unit for future missions. The spare models of DREAMS are currently in use at university premises for the development of autonomous units to be used in cubesat mission and in probes for stratospheric balloons launches in collaboration with Italian Space Agency

    Does the Underground Economy Hold Back Financial Deepening? Evidence from the Italian Credit Market

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