77 research outputs found

    Go East? Il perno asiatico degli equilibri mondiali come dilemma per l’Alleanza Atlantica

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    L’ascesa della Repubblica Popolare Cinese ha indotto gli Stati Uniti ad un ripensamento dei propri obiettivi e priorità strategiche, tra cui particolare rilievo ha assunto il riorientamento del baricentro della loro politica estera verso il quadrante Indo-pacifico. Nonostante alcuni Stati europei della Nato stiano iniziando a tributare maggior interesse alle dinamiche di sicurezza dell’area, le priorità strategiche dell’Alleanza Atlantica rimangono profondamente ancorate in Europa, lungo quel fianco est su cui si affaccia la Federazione Russa e quel fianco sud esposto all’ormai decennale instabilità degli Stati nord-africani. Il mutamento in corso, tuttavia, impone alla Nato di interrogarsi sul proprio futuro e sul dilemma strategico cui esso si trova intimamente legato: continuare ad essere un’alleanza con un raggio d’azione poco più che regionale oppure trasformarsi in un attore compiutamente globale che si confronta con il revisionismo cinese, ovvero con la grande sfida strategica del XXI secolo

    Polypropylene Embedded Metal-Mesh Broadband Achromatic Half Wave Plate for Millimeter Wavelengths

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    We describe a novel multi-layered metal mesh achromatic half wave plate for use in astronomical polarimetric instruments. The half wave plate is designed to operate across the frequency range from 125-250 GHz. The wave plate is manufactured from 12-layers of thin film metallic inductive and capacitive grids patterned onto polypropylene sheets, which are then bonded together using a hot pressing technique. Transmission line modelling and 3-D electromagnetic simulations are used to optimize the parameters of the metal-mesh patterns and to evaluate their optical properties. A prototype half wave plate has been fabricated and its performance characterized in a polarizing Fourier transform spectrometer. The device performance is consistent with the modelling although the measured differential phase shift for two orthogonal polarizations is lower than expected. This difference is likely to result from imperfect patterning of individual layers and misalignment of the grids during manufacture.Comment: 14 pages, 13 Figures, 1 Tabl

    An application of data-driven analysis in road tunnels monitoring

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    In order to comply with the minimum safety requirements imposed by the Directive 2004/54/EC it is of paramount mportance to correctly manage the operation and maintenance of road tunnels. This research describes how Artificial Intelligence techniques can play a supportive role both for maintenance operators in monitoring tunnels and for safety managers in operation. It is possible to extract relevant information from large volumes of data from sensor equipment in an efficient, fast, dynamic and adaptive way and make it immediately usable by those who manage machinery and servicesto aid quick decisions. Carrying out an analysis based on sensors in motorway tunnels, represents an important technological innovation, which would simplify tunnels management activities and therefore the detection of any possible deterioration, while keeping the risk within tolerance limits. The idea involves the creation of an algorithm for the detection of faults by acquiring data in real time from the sensors of tunnel sub-systems and using them to help identify the service state of the tunnel. The AI models are trained on a period of 6 months with one hour time series granularity measured on a road tunnel part of the Italian motorway systems. The verification has been done with reference to a number of recorded sensor faults

    The balloon-borne large-aperture submillimeter telescope for polarimetry: BLAST-Pol

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    The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLAST-Pol) is a suborbital mapping experiment designed to study the role played by magnetic fields in the star formation process. BLAST-Pol is the reconstructed BLAST telescope, with the addition of linear polarization capability. Using a 1.8 m Cassegrain telescope, BLAST-Pol images the sky onto a focal plane that consists of 280 bolometric detectors in three arrays, observing simultaneously at 250, 350, and 500 um. The diffraction-limited optical system provides a resolution of 30'' at 250 um. The polarimeter consists of photolithographic polarizing grids mounted in front of each bolometer/detector array. A rotating 4 K achromatic half-wave plate provides additional polarization modulation. With its unprecedented mapping speed and resolution, BLAST-Pol will produce three-color polarization maps for a large number of molecular clouds. The instrument provides a much needed bridge in spatial coverage between larger-scale, coarse resolution surveys and narrow field of view, and high resolution observations of substructure within molecular cloud cores. The first science flight will be from McMurdo Station, Antarctica in December 2010.Comment: 14 pages, 9 figures Submitted to SPIE Astronomical Telescopes and Instrumentation Conference 201

    Comparison of prestellar core elongations and large-scale molecular cloud structures in the Lupus 1 region

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    Turbulence and magnetic fields are expected to be important for regulating molecular cloud formation and evolution. However, their effects on sub-parsec to 100 parsec scales, leading to the formation of starless cores, are not well understood. We investigate the prestellar core structure morphologies obtained from analysis of the Herschel-SPIRE 350 mum maps of the Lupus I cloud. This distribution is first compared on a statistical basis to the large-scale shape of the main filament. We find the distribution of the elongation position angle of the cores to be consistent with a random distribution, which means no specific orientation of the morphology of the cores is observed with respect to the mean orientation of the large-scale filament in Lupus I, nor relative to a large-scale bent filament model. This distribution is also compared to the mean orientation of the large-scale magnetic fields probed at 350 mum with the Balloon-borne Large Aperture Telescope for Polarimetry during its 2010 campaign. Here again we do not find any correlation between the core morphology distribution and the average orientation of the magnetic fields on parsec scales. Our main conclusion is that the local filament dynamics---including secondary filaments that often run orthogonally to the primary filament---and possibly small-scale variations in the local magnetic field direction, could be the dominant factors for explaining the final orientation of each core

    The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): First Flight

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    The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter far-infrared (30-100 m) double-Fourier Michelson interferometer designed to fly on a high altitude scientific balloon. The project began in 2011, and the payload was declared ready for flight in September 2016. Due to bad weather, the first flight was postponed until June 2017; BETTII was successfully launched on June 8, 2017 for an engineering flight. Over the course of the one night flight, BETTII acquired a large amount of technical data that we are using to characterize the payload. Unfortunately, the flight ended with an anomaly that resulted in destruction of the payload. In this paper, we will discuss the path to BETTII flight, the results of the first flight, and some of the plans for the future

    Correlation between visual field index and quality of life in glaucoma patients: a new tool to screen quality of life perception?

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    PurposeTo evaluate the correlation between the visual field index (VFI) and vision-related quality of life (QoL) considering several confounding variables that may have a positive or negative effect.MethodsWe conducted a cross-sectional, mono-centric study on glaucoma patients. Quality of life was examined with the NEI-VFQ 25 and the Glaucoma Symptom Scale (GSS). The visual field was examined with the Humphrey Field Analyzer. The variables considered were age, gender, comorbidities, years (at diagnosis and duration of the illness), treatment and related active principles, intraocular pressure, and visual acuity. The analysis was performed on both the better and the worse eye. The linear regression univariate analysis and the multivariate analyses were performed.ResultsIn total, 193 patients enrolled in the study. The mean age was 70.8 ± 10.4 years. The mean follow-up period since diagnosis 11.4 ± 9.2 years. Approximately 50% of the patients suffered from primary open angle glaucoma (POAG) and 45% were on monotherapy. The mean VFI was 81.3 ± 26. Regarding QoL, the NEI-VFQ total mean was 80.4 ± 17.8 and the GSS total score was 77.2 ± 21. Regarding NEI-VFQ 25, the single linear regression analysis found the following relations: age at time of visit (r = −0.30, p = 0.016), years of illness (r = −0.32, p = 0.020), the minimum and maximal visual acuity (r = 2.04 and r = 3.96, p < 0.001), the IOP min (r = 1.13, p = 0.002) and max (r = −0.52, p = 0.017), and the number of previous surgeries (r = −3.94, p < 0.001). The multivariate analysis found the following relations: gender (r = 5.13, p = 0.019), visual acuity max (r = 3.16, p < 0.001), and previous surgeries (r = −1.80, p = 0.032). Regarding GSS, the single linear regression analysis found relations with visual acuity (r = 2.37, p < 0.001), VFI (r = 0.41, p < 0.001), previous surgeries in the eye considered (r = −7.27, p < 0.001), and number of instillations (r = −3.67, p = 0.031). Data confirmed that a higher VFI has a positive impact on the score of both the NEI-VFQ 25 (r = 0.22, p = < 0.001) and the GSS questionnaire (r = 0.36, p < 0.001).ConclusionsThe study demonstrated a correlation between the VFI and QoL of patients and their visual and non-visual ocular symptoms and function both in the worst and in the better eye, even when accounting for several clinical and demographic confounding variables. Our data support that the visual field index is an important metric instrument in the follow up of patients with glaucoma

    Empirical modelling of the BLASTPol achromatic half-wave plate for precision submillimetre polarimetry

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    A cryogenic achromatic half-wave plate (HWP) for submillimetre astronomical polarimetry has been designed, manufactured, tested and deployed in the Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry (BLASTPol). The design is based on the five-slab Pancharatnam recipe and itworks in thewavelength range 200–600 μm, making it the broadestband HWP built to date at (sub)millimetre wavelengths. The frequency behaviour of the HWP has been fully characterized at room and cryogenic temperatures with incoherent radiation from a polarizing Fourier transform spectrometer. We develop a novel empirical model, complementary to the physical and analytical ones available in the literature, that allows us to recover the HWP Mueller matrix and phase shift as a function of frequency and extrapolated to 4 K. We show that most of the HWP non-idealities can be modelled by quantifying one wavelength-dependent parameter, the position of the HWP equivalent axes, which is then readily implemented in a map-making algorithm. We derive this parameter for a range of spectral signatures of input astronomical sources relevant to BLASTPol, and provide a benchmark example of how our method can yield improved accuracy on measurements of the polarization angle on the sky at submillimetre wavelengths

    The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): towards the first flight

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    The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is a balloon-borne, far-infrared direct detection interferometer with a baseline of 8 m and two collectors of 50 cm. It is designed to study galactic clustered star formation by providing spatially-resolved spectroscopy of nearby star clusters. It is being assembled and tested at NASA Goddard Space Flight Center for a first flight in Fall 2016. We report on recent progress concerning the pointing control system and discuss the overall status of the project as it gets ready forits commissioning flight
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