49 research outputs found

    The masonry of the Terme di Elagabalo at the Palatine hill (Rome). Survey, analysis and quantification of a roman empire architecture

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    The NE slopes of the Palatine and the Colosseum valley area have been the place of a long archaeological research; here the continuous urban development produced an overlap of architectural complexes distributed over time. The huge amount of archaeological documentation produced during research is managed by an intra-site GIS. For ancient walls analysis we have introduced the use of image-based-modelling photogrammetry in order to create a very detailed 3D documentation, marked by an increasing and progressive high-level-autopsy, linked to a DBMS dedicated to ancient structural features. In this procedure we also decided to compare two different approaches to check results of both: one based on taking brick measures directly by hand, the other taking same measures on photogrammetric elaborations by GIS. Through this methodology, counting measures and dimensional aspect of wall facades features, we can evaluate specific aspects of the ancient construction yards for each period; we can also refine the chronological sequences of the architectures and verify the contextual relationships of the surrounding buildings in order to formulate wide-ranging reconstructive hypotheses

    Sun temple of Nyuserre in Abu Ghurab: Report of the 2017 season

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    The article presents the results of the 2017 archaeological season in the sun temple of Nyuserre in Abu Ghurab. The works especially focused on three areas, namely the central obelisk, the alabaster altar, and the accumulation of limestone blocks in the south-western corner of the temple. Besides the documentation of these archaeological remains, an in-depth architectural analysis of the above-mentioned structures has been carried out, in particular as regards the obelisk area. In fact, as already noticed in other contributions, the 3D reconstruction of this part of the temple provided by Borchardt is not convincing for a number of reasons. A new reconstruction of the latter part of the temple has therefore been proposed, based on several archaeological, architectural and historical elements. This reconstruction involves not only the architecture of the obelisk but also the original aspect of the altar area, which is strictly connected to the obelisk as regards the cult practice and the overall temple symbolism. Another objective of the mission was to lay the foundations to a new phase of investigation of the area outside the temple, in particular of the area to the south-east of the sun temple of Nyuserre where the analysis of data coming from satellite remote sensing and historical cartography seems to indicate the possible existence of archaeological remains so far unexplored. Starting from this year, the mission has also become a joint ItalianCzech expedition within the framework of a wider research project (The Rise and Development of the Solar Cult and Architecture in Third Millennium BC Egypt – GAČR project no. 17-10799S), launched in January 2017 at the Czech Institute of Egyptology, Charles (https://cegu.ff.cuni.cz/en/ research/grants/the-rise-of-solar-cult/)

    Preliminary surface charging analysis of Ariel payload dielectrics in early transfer orbit and L2-relevant space environment

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    Ariel [1] is the M4 mission of the ESA’s Cosmic Vision Program 2015-2025, whose aim is to characterize by lowresolution transit spectroscopy the atmospheres of over one thousand warm and hot exoplanets orbiting nearby stars. The operational orbit of the spacecraft is baselined as a large amplitude halo orbit around the Sun-Earth L2 Lagrangian point, as it offers the possibility of long uninterrupted observations in a fairly stable radiative and thermo-mechanical environment. A direct escape injection with a single passage through the Earth radiation belts and no eclipses is foreseen. The space environment around Earth and L2 presents significant design challenges to all spacecraft, including the effects of interactions with Sun radiation and charged particles owning to the surrounding plasma environment, potentially leading to dielectrics charging and unwanted electrostatic discharge (ESD) phenomena endangering the Payload operations and its data integrity. Here, we present some preliminary simulations and analyses about the Ariel Payload dielectrics and semiconductors charging along the transfer orbit from launch to L2 include

    FEA testing the pre-flight Ariel primary mirror

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    Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) is an ESA M class mission aimed at the study of exoplanets. The satellite will orbit in the lagrangian point L2 and will survey a sample of 1000 exoplanets simultaneously in visible and infrared wavelengths. The challenging scientific goal of Ariel implies unprecedented engineering efforts to satisfy the severe requirements coming from the science in terms of accuracy. The most important specification – an all-Aluminum telescope – requires very accurate design of the primary mirror (M1), a novel, off-set paraboloid honeycomb mirror with ribs, edge, and reflective surface. To validate such a mirror, some tests were carried out on a prototype – namely Pathfinder Telescope Mirror (PTM) – built specifically for this purpose. These tests, carried out at the Centre Spatial de Liège in Belgium – revealed an unexpected deformation of the reflecting surface exceeding a peek-to-valley of 1µm. Consequently, the test had to be re-run, to identify systematic errors and correct the setting for future tests on the final prototype M1. To avoid the very expensive procedure of developing a new prototype and testing it both at room and cryogenic temperatures, it was decided to carry out some numerical simulations. These analyses allowed first to recognize and understand the reasoning behind the faults occurred during the testing phase, and later to apply the obtained knowledge to a new M1 design to set a defined guideline for future testing campaigns

    The Association of PNPLA3 Variants with Liver Enzymes in Childhood Obesity Is Driven by the Interaction with Abdominal Fat

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    BACKGROUND AND AIMS: A polymorphism in adiponutrin/patatin-like phospholipase-3 gene (PNPLA3), rs738409 C->G, encoding for the I148M variant, is the strongest genetic determinant of liver fat and ALT levels in adulthood and childhood obesity. Aims of this study were i) to analyse in a large group of obese children the role of the interaction of not-genetic factors such as BMI, waist circumference (W/Hr) and insulin resistance (HOMA-IR) in exposing the association between the I148M polymorphism and ALT levels and ii) to stratify the individual risk of these children to have liver injury on the basis of this gene-environment interaction. METHODS: 1048 Italian obese children were investigated. Anthropometric, clinical and metabolic data were collected and the PNPLA3 I148M variant genotyped. RESULTS: Children carrying the 148M allele showed higher ALT and AST levels (p = 0.000006 and p = 0.0002, respectively). Relationships between BMI-SDS, HOMA-IR and W/Hr with ALT were analysed in function of the different PNPLA3 genotypes. Children 148M homozygous showed a stronger correlation between ALT and W/Hr than those carrying the other genotypes (p: 0.0045) and, therefore, 148M homozygotes with high extent of abdominal fat (W/Hr above 0.62) had the highest OR (4.9, 95% C. I. 3.2-7.8, p = 0.00001) to develop pathologic ALT. CONCLUSIONS: We have i) showed for the first time that the magnitude of the association of PNPLA3 with liver enzymes is driven by the size of abdominal fat and ii) stratified the individual risk to develop liver damage on the basis of the interaction between the PNPLA3 genotype and abdominal fat

    IXPE instrument integration, testing and verification

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    The Imaging X-ray Polarimetry Explorer (IXPE) is a scientific observatory with the purpose of expand observation space adding polarization property to the X-ray source's currently measured characteristics. The mission selected in the context of NASA Small Explorer (SMEX) is a collaboration between NASA and ASI that will provide to observatory the instrumentation of focal plane. IXPE instrument is composed by three photoelectric polarimeters based on the Gas Pixel Detector (GPD) design, integrated by INFN inside the detector unit (DU) that comprises of the electrical interfaces required to control and communicate with the GPD. The three DUs are interfaced with spacecraft through a detector service unit (DSU) that collect scientific and ancillary data and provides a basically data handling and interfaces to manage the three DUs. AIV has been planned to combine calibration of DUs and Instrument integration and verification activities. Due the tight schedule and the scientific and functional requirements to be verified, in IAPS/INAF have been assembled two equipment's that work in parallel. The flight model of each DU after the environmental tests campaign was calibrated on-ground using the Instrument Calibration Equipment (ICE) and subsequently integrated in the instrument in the AIV-T process on a AIV and Calibration Equipment (ACE), both the facilities managed by Electrical Ground Support Equipment (EGSE) that emulate the spacecraft interfaces of power supply, functional and thermal control and scientific data collection. AIV activities test functionalities and nominal/off-nominal orbits activities of IXPE instrument each time a calibrated DU is connected to DSU flight model completing step by step the full instrument. Here we describe the details of instrumentation and procedures adopted to make possible the full integration and test activities compatibly with calibration of IXPE Instrument

    The IXPE Instrument Calibration Equipment

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    The Imaging X-ray Polarimetry Explorer is a mission dedicated to the measurement of X-ray polarization from tens of astrophysical sources belonging to different classes. Expected to be launched at the end of 2021, the payload comprises three mirrors and three focal plane imaging polarimeters, the latter being designed and built in Italy. While calibration is always an essential phase in the development of high-energy space missions, for IXPE it has been particularly extensive both to calibrate the response to polarization, which is peculiar to IXPE, and to achieve a statistical uncertainty below the expected sensitivity. In this paper we present the calibration equipment that was designed and built at INAF-IAPS in Rome, Italy, for the calibration of the polarization-sensitive focal plane detectors on-board IXPE. Equipment includes calibration sources, both polarized and unpolarized, stages to align and move the beam, test detectors and their mechanical assembly. While all these equipments were designed to fit the specific needs of the IXPE Instrument calibration, their versatility could also be used in the future for other projects
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