334 research outputs found

    Examples of application of tensorial resistivity probability tomography to architectonic and archaeological targets

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    We present the results of the application of the tensor resistivity method to the assessment of the state of conservation of some architectonic features of the S.Giovanni a Carbonara monumental monastery (Naples, Italy) and to the recognition of buried remains in the archaeological site of the roman Port of Claudius at Fiumicino (Rome, Italy). The 3D tomographic approach, based on the concept of resistivity anomaly source occurrence probability, has been used for the analysis of the invariant parameter related to the trace of the determinant of the apparent resistivity tensor

    The tsumani detector prototype installed on board of SN1-cabled abyssal station.

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    The new stand-alone tsunami detector prototype designed to operate in tsunami generation areas, already tested in the Gulf of Cadiz (SW Iberia) on board of GEOSTAR abyssal station, has been re-designed to be hosted on the cabled SN1 abyssal station. A new control software has been implemented to manage, in real time, from the land-based control room the basic component of the tsunameter. The tsunami detection software which perform the real time analysis of the parent tsunami signals, differently form the Gulf of Cadiz stand-alone prototype, runs on a land-based PC. Moreover, the cabled tsunameter is equipped with a new low-frequency hydrophone to detect the hydro-acoustic noise and signals that may be related to tsunami generation

    The tsumani detector prototype deployed in the Gulf of Cadiz: data collection and functionality evaluation

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    A new tsunami detector prototype designed to operate in tsunami generation areas has been tested offshore SW Iberia, in the Gulf of Cadiz. The prototype, hosted on board of GEOSTAR has been deployed, at to 3200 meters depth, in August 2007 and recovered one year later by R/V Urania. After refurbishment and a partial upgrade, the tsunameter has been re-deployed in the same location on November 2009 by R/V Sarmiento de Gamboa.We report samples of the data collected by the pressure sensors and the critical analysis of the achievements and problems faced during these test periods

    The structures of Hausdorff metric in non-Archimedean spaces

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    For non-Archimedean spaces X X and Y, Y, let M♭(X),M(V→W) \mathcal{M}_{\flat } (X), \mathfrak{M}(V \rightarrow W) and D♭(X,Y) \mathfrak{D}_{\flat }(X, Y) be the ballean of X X (the family of the balls in X X ), the space of mappings from X X to Y, Y, and the space of mappings from the ballen of X X to Y, Y, respectively. By studying explicitly the Hausdorff metric structures related to these spaces, we construct several families of new metric structures (e.g., ρ^u,ÎČ^X,Yλ,ÎČ^X,Y∗λ \widehat{\rho } _{u}, \widehat{\beta }_{X, Y}^{\lambda }, \widehat{\beta }_{X, Y}^{\ast \lambda } ) on the corresponding spaces, and study their convergence, structural relation, law of variation in the variable λ, \lambda, including some normed algebra structure. To some extent, the class ÎČ^X,Yλ \widehat{\beta }_{X, Y}^{\lambda } is a counterpart of the usual Levy-Prohorov metric in the probability measure spaces, but it behaves very differently, and is interesting in itself. Moreover, when X X is compact and Y=K Y = K is a complete non-Archimedean field, we construct and study a Dudly type metric of the space of K− K-valued measures on X. X. Comment: 43 pages; this is the final version. Thanks to the anonymous referee's helpful comments, the original Theorem 2.10 is removed, Proposition 2.10 is stated now in a stronger form, the abstact is rewritten, the Monna-Springer is used in Section 5, and Theorem 5.2 is written in a more general for

    Environmental impact of early palaeometallurgy: pollen and geochemical analysis

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    International audienceInterdisciplinary research was carried out in mid-level mountain areas in France with the aim of documenting historical mining and smelting activities by means of pollen and geochemical analyses. These investigations were made on cores collected in French peatlands in the Morvan (northern Massif Central), at Mont LozÚre (southern Massif Central) and in the Basque Country (Pyrénées). Different periods of mining were recognised from Prehistory to modern times through the presence of anthropogenic lead in peat. Some of these were already known from archaeological dates or historical archives, especially for mediaeval and modern periods. However prehistoric ancient mining activities, as early as the Middle Bronze Age (ca. 1700 b.c.), were also discovered. They had all led to modifications in plant cover, probably related in part to forest clearance necessary to supply energy for mining and smelting

    Tsunami Early Warning System: Deep Sea Measurements in the Source Area

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    In the framework of the EU project NEAREST, a new Tsunami Early Warning System (TEWS), able to operate in tsunami generation areas, was developed and installed in the Gulf of Cadiz. The TEWS is based on the abyssal station GEOSTAR, placed above a major tsunamigenic structure, and on three seismic centres of Portugal, Spain and Morocco. The core of the system is a tsunami detector installed onboard of GEOSTAR. The tsunami detector communicates with a surface buoy through a dual acoustic link. The buoy is connected to land stations via satellite link. The system was designed for near-field conditions and successfully operated from August 2007 to August 2008, 100 km SW of Cabo de Sao Vincente (Portugal). A new mission started on November 11th, 2009 in the same location. The tsunami detection is based either on pressure events either on seismic events. The bottom pressure data are analysed in real-time at the seafloor by a new tsunami detection algorithm, which can recognize tsunami waves as small as one centimetre. At the same time it was developed a new theoretical approach to account for tsunami generation in compressible water and in presence of a porous sediment. This model showed that hydro-acoustic waves, travelling much faster than the tsunami, are caused by the seafloor motion. These waves can propagate outside the generation area and are characterised by a modulation carrying valuable information on the seafloor motion, which can be recovered from their first arrival

    CLASH: A Census of Magnified Star-Forming Galaxies at z ~ 6-8

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    We utilize 16 band Hubble Space Telescope (HST) observations of 18 lensing clusters obtained as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) Multi-Cycle Treasury program to search for z∌6−8z\sim6-8 galaxies. We report the discovery of 204, 45, and 13 Lyman-break galaxy candidates at z∌6z\sim6, z∌7z\sim7, and z∌8z\sim8, respectively, identified from purely photometric redshift selections. This large sample, representing nearly an order of magnitude increase in the number of magnified star-forming galaxies at z∌6−8z\sim 6-8 presented to date, is unique in that we have observations in four WFC3/UVIS UV, seven ACS/WFC optical, and all five WFC3/IR broadband filters, which enable very accurate photometric redshift selections. We construct detailed lensing models for 17 of the 18 clusters to estimate object magnifications and to identify two new multiply lensed z≳6z \gtrsim 6 candidates. The median magnifications over the 17 clusters are 4, 4, and 5 for the z∌6z\sim6, z∌7z\sim7, and z∌8z\sim8 samples, respectively, over an average area of 4.5 arcmin2^2 per cluster. We compare our observed number counts with expectations based on convolving "blank" field UV luminosity functions through our cluster lens models and find rough agreement down to ∌27\sim27 mag, where we begin to suffer significant incompleteness. In all three redshift bins, we find a higher number density at brighter observed magnitudes than the field predictions, empirically demonstrating for the first time the enhanced efficiency of lensing clusters over field surveys. Our number counts also are in general agreement with the lensed expectations from the cluster models, especially at z∌6z\sim6, where we have the best statistics.Comment: Accepted for publication in the Astrophysical Journal, 25 pages, 13 figures, 7 table

    CLASH: Extending galaxy strong lensing to small physical scales with distant sources highly-magnified by galaxy cluster members

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    We present a strong lensing system in which a double source is imaged 5 times by 2 early-type galaxies. We take advantage in this target of the multi-band photometry obtained as part of the CLASH program, complemented by the spectroscopic data of the VLT/VIMOS and FORS2 follow-up campaign. We use a photometric redshift of 3.7 for the source and confirm spectroscopically the membership of the 2 lenses to the galaxy cluster MACS J1206.2-0847 at redshift 0.44. We exploit the excellent angular resolution of the HST/ACS images to model the 2 lenses in terms of singular isothermal sphere profiles and derive robust effective velocity dispersions of (97 +/- 3) and (240 +/- 6) km/s. The total mass distribution of the cluster is also well characterized by using only the local information contained in this lensing system, that is located at a projected distance of more than 300 kpc from the cluster luminosity center. According to our best-fitting lensing and composite stellar population models, the source is magnified by a total factor of 50 and has a luminous mass of about (1.0 +/- 0.5) x 10^{9} M_{Sun}. By combining the total and luminous mass estimates of the 2 lenses, we measure luminous over total mass fractions projected within the effective radii of 0.51 +/- 0.21 and 0.80 +/- 0.32. With these lenses we can extend the analysis of the mass properties of lens early-type galaxies by factors that are about 2 and 3 times smaller than previously done with regard to, respectively, velocity dispersion and luminous mass. The comparison of the total and luminous quantities of our lenses with those of astrophysical objects with different physical scales reveals the potential of studies of this kind for investigating the internal structure of galaxies. These studies, made possible thanks to the CLASH survey, will allow us to go beyond the current limits posed by the available lens samples in the field.Comment: 20 pages, 10 figures, accepted for publication in the Astrophysical Journa

    NEMO-SN1 (Western Ionian Sea, off Eastern Sicily): A Cabled Abyssal Observatory with Tsunami Early Warning Capability

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    The NEMO-SN1 (NEutrino Mediterranean Observatory - Submarine Network 1) seafloor observatory is located in the central Mediterranean, Western Ionian Sea, off Eastern Sicily Island (Southern Italy) at 2100 m water depth, 25 km from the harbour of the city of Catania. It is a prototype of cabled deep-sea multiparameter observatory, and the first operating with real-time data transmission in Europe since 2005. NEMO-SN1 is also the first-established node of EMSO (European Multidisciplinary Seafloor Observatory, http://emso-eu.org), one of the European large-scale research infrastructures. EMSO will address long-term monitoring of environmental processes related to marine ecosystems, climate change and geo-hazards. NEMO-SN1 will perform geophysical and environmental long-term monitoring by acquiring seismological, geomagnetic, gravimetric, accelerometric, physico-oceanographic, hydro-acoustic, bio-acoustic measurements to study earthquake and tsunami generation, and to characterize ambient noise which includes marine mammal sounds, and environmental and anthropogenic sources. NEMO-SN1 is also equipped with a prototype tsunami detector, based on the simultaneous measurement of the seismic and bottom pressure signals and a new high performance tsunami detection algorithm. NEMO-SN1 will be a permanent tsunami early warning node in Western Ionian Sea, an area where very destructive earthquakes have occurred in the past, some of them tsunamigenic (e.g., 1693, M=7.5; 1908, M=7.4). Another important feature of NEMO-SN1 is the installation of a low frequency-high sensibility hydrophone and two (scalar and vector, respectively) magnetometers. The objective is to improve the tsunami detection capability of SN1 through the recognition of tsunami-induced hydro-acoustic and electro-magnetic precursors.SubmittedRhodes, Greece3A. Ambiente Marinorestricte

    An innovative tsunami detector operating in tsunami generation environment

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    On August 25th 2007 a tsunami detector installed onboard the multi-parameter observatory GEOSTAR was successfully deployed at 3200 b. s. l. in the Gulf of Cadiz, Portugal. This activity is within the NEAREST EC Project (http://nearest.bo.ismar.cnr.it/ ). Among other deliverables, the NEAREST project will produce and test the basic parts of an operational prototype of a near field tsunami warning system. This system includes an onshore warning centre, based on the geophysical monitoring networks which are already operating, and a tsunami detector deployed on board GEOSTAR at the sea bottom. On land the warning centre is in charge of collecting, integrating, and evaluating data recorded at sea. At the sea bottom data is recorded and processed by an advanced type of tsunami detector which includes: a pressure sensor, a seismometer and two accelerometers. The detector communicates acoustically with a surface buoy in two-way mode. The buoy is equipped with meteo station, GPS and tiltmeter and is connected to a shore station via satellite link. The prototype is designed to operate in tsunami generation areas for detection-warning purpose as well as for scientific measurements. The tsunami detector sends a near real time automatic alert message when a seismic or pressure threshold are exceeded. Pressure signals are processed by the tsunami detection algorithm and the water pressure perturbation caused by the seafloor motion is taken into account. The algorithm is designed to detect small tsunami waves, less than one centimetre, in a very noisy environment. Our objective is to combine a novel approach to the tsunami warning problem, with a study of the coupling between the water column perturbations and sea floor motion, together with the long term monitoring of geophysical, geochemical and oceanographic parameters
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