306 research outputs found

    A Critical Review of the Recent Improvements in Minimizing Nuclear Waste by Innovative Gas-Cooled Reactors

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    This paper presents a critical review of the recent improvements in minimizing nuclear waste in terms of quantities, long-term activities, and radiotoxicities by innovative GCRs, with particular emphasis to the results obtained at the University of Pisa. Regarding these last items, in the frame of some EU projects (GCFR, PUMA, and RAPHAEL), we analyzed symbiotic fuel cycles coupling current LWRs with HTRs, finally closing the cycle by GCFRs. Particularly, we analyzed fertile-free and Pu-Th-based fuel in HTR: we improved plutonium exploitation also by optimizing Pu/Th ratios in the fuel loaded in an HTR. Then, we chose GCFRs to burn residual MA. We have started the calculations on simplified models, but we ended them using more "realistic" models of the reactors. In addition, we have added the GCFR multiple recycling option usingkeffcalculations for all the reactors. As a conclusion, we can state that, coupling HTR with GCFR, the geological disposal issues concerning high-level radiotoxicity of MA can be considerably reduced

    Evaluation of fetal cerebral blood flow perfusion using power Doppler Ultrasound Angiography (3D-PDA) in growth-restricted fetuses

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    Objective: to explore the potential of 3D Power Doppler Angiography (3D PDA) to evaluate the cerebral circulation in normal and growth restricted fetuses (IUGR). Study design: in a pilot study, we enrolled 51 appropriate for gestational age (AGA) pregnancies and 17 singleton pregnancies presenting IUGR, all between 22 and 38 weeks of gestation. Using 3D power Doppler ultrasound, a volume acquisition of the fetal brain was performed. Two regions of interest (ROI) were defined within the fetal brain. Zone 1 is anterior to the cavum septi pellucidi (CSP). Zone 2 is defined by a rectangle obtained tracing a contour between the temporal bones as wide as the CSP, corresponding to the area of the middle cerebral artery. The Flow Index (FI), the Vascularization Index (VI), the Vascularization and Flow Index (VFI) were determined in both areas in both IUGR and AGA fetuses by a single operator. IUGR fetuses were divided into three groups: Group 1, with normal pulsatility index (PI) of umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV); Group 2, IUGR fetuses with abnormal UA PI, normal MCA PI, normal DV PI; in Group 3, IUGR fetuses with abnormal UA PI, MCA PI and DV PI. Results: FI and VFI values of zone 1 were increased in Group 1.Values of VFI in zone 2 were increased in Group 2. Conclusions: Our findings are in line with recent studies in growth-restricted fetuses suggesting that the anterior cerebral artery shows Doppler signs of vasodilatation before these are observed in the MCA, demonstrating the “frontal brain sparing effect”

    Barriers and Enablers for Industry 4.0 in SMEs: A Combined Integration Framework

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    Although Industry 4.0 was introduced a decade ago, many small and medium-sized enterprises (SMEs) still have not adopted several technologies. Therefore, integrating SMEs along horizontal, vertical, and end-to-end engineering dimensions remains challenging. Due to the importance of SMEs for industrial value chains, understanding SMEs' barriers and respective enablers for Industry 4.0 integration is vital. Applying a multiple case study approach, this paper investigates their experience in Industry 4.0 through technological, organizational, and environmental factors. We aggregate the barriers and respective enablers to Industry 4.0 into an integration framework, which helps to understand Industry 4.0 in SMEs from a broader viewpoint inside these firms, upstream and downstream supply chains, and beyond manufacturing. The findings show that the success of Industry 4.0 integration is more oriented toward operational benefits than strategic advantages and depends upon how these technologies are integrated with various stakeholders across the supply chain, such as original equipment manufacturers, R&D agencies, or sub-suppliers

    Bidirectional Communication System on Power Line Integrated on Electronic Board for Driving of LED and HID Lamps

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    We present the bidirectional power line communication system developed in parallel to an electronic board for driving and control of HID (high-intensity discharge) and LED (light-emitting diode) lamps. The communication system, developed to be applied in the sector of public illumination, is been designed to combine high efficiency and reliability with low production costs; it consists indeed of discrete cheap components. The communication system described in this paper implements the technique of transporting digital information over existing power lines, avoiding the issue of installing new cables. Digitized signals can use power line cables through the amplitude voltage and current modulation. The solution proposed is more advantageous compared to communication techniques currently on the market which are essentially two types, power line carrier (modem for high-voltage lines) or radio (zig-Bee transceiver)

    Neuropsychological and neurophysiological correlates of fatigue in post-acute patients with neurological manifestations of COVID-19: Insights into a challenging symptom

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    More than half of patients who recover from COVID-19 experience fatigue. We studied fatigue using neuropsychological and neurophysiological investigations in post-COVID-19 patients and healthy subjects. Neuropsychological assessment included: Fatigue Severity Scale (FSS), Fatigue Rating Scale, Beck Depression Inventory, Apathy Evaluation Scale, cognitive tests, and computerized tasks. Neurophysiological examination was assessed before (PRE) and 2 min after (POST) a 1-min fatiguing isometric pinching task and included: maximum compound muscle action potential (CMAP) amplitude in first dorsal interosseous muscle (FDI) following ulnar nerve stimulation, resting motor threshold, motor evoked potential (MEP) amplitude and silent period (SP) duration in right FDI following transcranial magnetic stimulation of the left motor cortex. Maximum pinch strength was measured. Perceived exertion was assessed with the Borg-Category-Ratio scale. Patients manifested fatigue, apathy, executive deficits, impaired cognitive control, and reduction in global cognition. Perceived exertion was higher in patients. CMAP and MEP were smaller in patients both PRE and POST. CMAP did not change in either group from PRE to POST, while MEP amplitudes declined in controls POST. SP duration did not differ between groups PRE, increased in controls but decreased in patients POST. Patients' change of SP duration from PRE to POST was negatively correlated to FSS. Abnormal SP shortening and lack of MEP depression concur with a reduction in post-exhaustion corticomotor inhibition, suggesting a possible GABAB-ergic dysfunction. This impairment might be related to the neuropsychological alterations. COVID-19-associated inflammation might lead to GABAergic impairment, possibly representing the basis of fatigue and explaining apathy and executive deficits

    AMICO galaxy clusters in KiDS-DR3: Cosmological constraints from angular power spectrum and correlation function

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    We study the tomographic clustering properties of the photometric cluster catalogue derived from the Third Data Release of the Kilo Degree Survey, focusing on the angular correlation function and its spherical harmonic counterpart, the angular power spectrum. We measure the angular correlation function and power spectrum from a sample of 5162 clusters, with an intrinsic richness λ15\lambda^*\geq 15, in the photometric redshift range z[0.1,0.6]z\in [0.1, 0.6], comparing our measurements with theoretical models, in the framework of the Λ\Lambda-Cold Dark Matter cosmology. We perform a Monte Carlo Markov Chain analysis to constrain the cosmological parameters Ωm\Omega_{\mathrm{m}}, σ8\sigma_8 and the structure growth parameter S8σ8Ωm/0.3S_8\equiv\sigma_8 \sqrt{\Omega_{\mathrm{m}}/0.3}. We adopt Gaussian priors on the parameters of the mass-richness relation, based on the posterior distributions derived from a previous joint analysis of cluster counts and weak lensing mass measurements carried out with the same catalogue. From the angular correlation function, we obtain Ωm=0.320.04+0.05\Omega_{\mathrm{m}}=0.32^{+0.05}_{-0.04}, σ8=0.770.09+0.13\sigma_8=0.77^{+0.13}_{-0.09} and S8=0.800.06+0.08S_8=0.80^{+0.08}_{-0.06}, in agreement, within 1σ1\sigma, with 3D clustering result based on the same cluster sample and with existing complementary studies on other datasets. For the angular power spectrum, we derive statistically consistent results, in particular Ωm=0.240.04+0.05\Omega_{\mathrm{m}}=0.24^{+0.05}_{-0.04} and S8=0.930.12+0.11S_8=0.93^{+0.11}_{-0.12}, while the constraint on σ8\sigma_8 alone is weaker with respect to the one provided by the angular correlation function, σ8=1.010.17+0.25\sigma_8=1.01^{+0.25}_{-0.17}. Our results show that the 2D clustering from photometric cluster surveys can provide competitive cosmological constraints with respect to the full 3D clustering statistics, and can be successfully applied to ongoing and forthcoming spectro/photometric surveys.Comment: 14 pages, 9 figures. Submitted to Astronomy & Astrophysics (A&A
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