99 research outputs found

    From bottom landers to observatory networks

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    For a long time, deep-sea investigation relied on autonomous bottom landers. Landers can vary in size from 200 kg weight to more than 2 t for the heaviest scientific landers and are used during exploration cruises on medium periods, from one week to some months. Today, new requirements appear. Scientists want to understand in detail the phenomena outlined during exploration cruises, to elaborate a model for future forecasting. For this, it is necessary to deploy instrumentation at a precise location often for a long period. A new mode of ocean science investigation using longterm seafloor observatories to obtain four dimensional data sets has appeared. Although this concept has been proposed for many years, the high level of investment required limits the number of projects implemented. Only multidisciplinary programs, supported by a strong social requirement were funded. Some observatories have been deployed

    European Seafloor Observatory Offers New Possibilities For Deep Sea Study

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    The Geophysical and Oceanographic Station for Abyssal Research (GEOSTAR), an autonomous seafloor observatory that collects measurements benefiting a number of disciplines during missions up to 1 year long, will begin the second phase of its first mission in 2000. The 6-8 month investigation will take place at a depth of 3400 m in the southern Tyrrhenian basin of the southern Tyrrhenian basin of the central Mediterranean. GEOSTAR was funded by the European Community (EC) for 2.4million(U.S.dollars)in1995asapartoftheMarineScienceandTechnologyprogramme(MAST).TheinnovativedeploymentandrecoveryprocedureGEOSTARuseswasderivedfromthe"two−module"conceptsuccessfullyappliedbyNASAintheApolloandspaceshuttlemissions,whereonemoduleperformstasksfortheother,includingdeployment,switchingonandoff,performingchecksandrecovery.Theobservatorycommunicationsystem,whichtakesadvantageofsatellitetelemetry,andthesimultaneousacquisitionofasetofvariousmeasurementswithauniquetimereferencemakeGEOSTARthefirstfundamentalelementofamultiparameteroceannetwork.GEOSTAR′sfirstscientificandtechnologicalmission,whichtookplaceinthesummerof1998intheAdriaticSea,verifiedtheperformanceandreliabilityofthesystem.Themissionwasasuccess.providing440hoursofcontinuousseismicmagneticandoceanographicdata.Thjesecondphaseofthemission,whichwasfundedbytheECfor2.4 million (U.S. dollars) in 1995 as a part of the Marine Science and Technology programme (MAST). The innovative deployment and recovery procedure GEOSTAR uses was derived from the "two-module" concept successfully applied by NASA in the Apollo and space shuttle missions, where one module performs tasks for the other, including deployment, switching on and off, performing checks and recovery. The observatory communication system, which takes advantage of satellite telemetry, and the simultaneous acquisition of a set of various measurements with a unique time reference make GEOSTAR the first fundamental element of a multiparameter ocean network. GEOSTAR's first scientific and technological mission, which took place in the summer of 1998 in the Adriatic Sea, verified the performance and reliability of the system. The mission was a success. providing 440 hours of continuous seismic magnetic and oceanographic data. Thje second phase of the mission, which was funded by the EC for 2 million (US dollars), will carry equipment for chemical, biological and isotopic analyses not used in the first phase, which will broaden the data collection effort.Published45, 48-492.5. Laboratorio per lo sviluppo di sistemi di rilevamento sottomariniN/A or not JCRreserve

    Single-frame multiparameter platforms for seafloor geophysical and environmental observations: projects and missons from GEOSTAR to ORION

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    The paper presents an overview of recent seafloor long-term single-frame multiparameter platform developed in the framework of the European Commission and Italian projects starting from the GEOSTAR prototype. The main features of the different systems are described as well as the sea missions that led to their validation. The ORION seafloor observatory network recently developed, based on the GEOSTAR-type platforms and engaged in a deep-sea mission at 3300 m w.d. in the Mediterranean Sea, is also describe

    A fleet of multiparameter observatories for geophysical and environmental monitoring at seafloor

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    Seafloor long-term, multiparameter, single-frame observatories have been developed within the framework of European Commission and Italian projects since 1995. A fleet of five seafloor observatories, built-up starting from 1995 within the framework of an effective synergy among research institutes and industries, have carried out a series of long-term sea experiments. The observatories are able to operate from shallow waters to deep sea, down to 4,000 m w.d., and to simultaneously monitor a broad spectrum of geophysical and environmental processes, including seismicity, geomagnetic field variations, water temperature, pressure, salinity, chemistry, currents, and gas occurrence. Moreover, they can transmit data in (near)-real-time that can be integrated with those of the on-land networks. The architecture of the seafloor observatories follows the criteria of modularity, interoperability and standardisation in terms of materials, components and communication protocols. This paper describes the technical features of the observatories, their experiments and data

    Detection potential of the KM3NeT detector for high-energy neutrinos from the Fermi bubbles

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    A recent analysis of the Fermi Large Area Telescope data provided evidence for a high-intensity emission of high-energy gamma rays with a E 2 spectrum from two large areas, spanning 50 above and below the Galactic centre (the ‘‘Fermi bubbles’’). A hadronic mechanism was proposed for this gamma-ray emission making the Fermi bubbles promising source candidates of high-energy neutrino emission. In this work Monte Carlo simulations regarding the detectability of high-energy neutrinos from the Fermi bubbles with the future multi-km3 neutrino telescope KM3NeT in the Mediterranean Sea are presented. Under the hypothesis that the gamma-ray emission is completely due to hadronic processes, the results indicate that neutrinos from the bubbles could be discovered in about one year of operation, for a neutrino spectrum with a cutoff at 100 TeV and a detector with about 6 km3 of instrumented volume. The effect of a possible lower cutoff is also considered.Published7–141.8. Osservazioni di geofisica ambientaleJCR Journalrestricte

    Expansion cone for the 3-inch PMTs of the KM3NeT optical modules

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    [EN] Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45 degrees with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.This work is supported through the EU, FP6 Contract no. 011937, FP7 grant agreement no. 212252, and the Dutch Ministry of Education, Culture and Science.Adrián Martínez, S.; Ageron, M.; Aguilar, JA.; Aharonian, F.; Aiello, S.; Albert, A.; Alexandri, M.... (2013). Expansion cone for the 3-inch PMTs of the KM3NeT optical modules. Journal of Instrumentation. 8(3):1-19. https://doi.org/10.1088/1748-0221/8/03/T03006S1198

    CD4 molecules are restricted to the basolateral membrane domain of in vitro differentiated human colon cancer cells (HT29-D4).

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    International audienceThe CD4 glycoprotein serves as a receptor for the human immunodeficiency virus HIV, the etiologic agent of acquired immunodeficiency syndrome (AIDS). We have examined the expression of CD4 molecules in a clone (HT29-D4) derived from a human colon adenocarcinoma cell line. HT29-D4 cells synthesized a 60 kDa polypeptide immunoprecipitated with two anti-CD4 monoclonal antibodies after metabolic or cell surface labeling. This 60 kDa polypeptide was also immunodetected using the same antibodies in human acute lymphoblastic leukemia cells CEM which are known to express CD4. HT29-D4 cells can be induced to differentiate into enterocyte-like cells by removing glucose from the culture medium. Under these conditions, HT29-D4 cells form a polarized epithelial monolayer in which tight junctions separate the plasma membrane in an apical and a basolateral domain. The localization of CD4 molecules in differentiated HT29-D4 cells was exclusively restricted to the basolateral membrane domain as demonstrated by radioimmunoassay and indirect immunofluorescence studies. Therefore the HT29-D4 clonal cell line represents a unique model for polarized HIV infection of colonic epithelial cells and may be useful to understand some of the gastrointestinal disorders occurring in AIDS patients
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