Predictive role of nasal functionality tests in the evaluation of patients before nocturnal polysomnographic recording

Obstructive sleep apnoea syndrome is a disease characterized by a collapse of the pharyngeal airway resulting in repeated episodes of airflow cessation, oxygen desaturation, and sleep disruption. It is a common disorder affecting at least 2-4% of the adult population. The role of nasal resistance in the pathogenesis of sleep disordered breathing and sleep apnoea has not been completely clarified. Aim of the present study was to establish whether nasal resistance and nasal volumes, measured by means of Active Anterior Rhinomanometry and Acoustic Rhinometry together with Muco-Ciliary Transport time play a positive predictive role in the evaluation of Obstructive sleep apnoea syndrome patients before running a nocturnal polysomnographic recording. A retrospective study was performed analysing 223 patients referred for suspected Obstructive sleep apnoea syndrome. All patients were submitted to complete otorhinolaryngological evaluation and underwent nocturnal polysomnography. On the basis of polysomnographic data analysis, the apnoea-hypopnoea index and snoring index, patients were classified into two groups: Group 1 (110/223 patients) with a diagnosis of mild-moderate Obstructive sleep apnoea syndrome (apnoea-hypopnoea index < 30) and Group 2 (113/223 patients) affected by snoring without associated hypoxaemia/hypercapnia. A control group of 76 subjects, not complaining of sleep disorders and free from nasal symptoms was also selected. The results showed, in all the snoring and Obstructive sleep apnoea syndrome patients, total nasal resistance and increased Muco-Ciliary Transport time compared to standard values. Furthermore, the apnoea-hypopnoea index was significantly higher in patients with higher nasal resistence and significantly different between the groups. These results allow us to propose the simultaneous evaluation of nasal functions by Active Anterior Rhinomanometry, Acoustic Rhinometry, and Muco-Ciliary Transport time in the selection of patients undergoing polysomnography

Nuclear loads and nuclear shielding performance of EU DEMO divertor: A comparative neutronics evaluation of two interim design options

In a demonstrational fusion power plant (DEMO), divertor is supposed to protect vacuum vessel and superconducting magnets against neutron flux in the bottom region of the vessel. The vessel is subject to a strict design limit in irradiation damage dose and the magnets in nuclear heating power, respectively. Thus, the DEMO divertor must have the capability to protect sufficiently the vessel and the magnets against neutron flux being substantially stronger than in ITER.In this paper, a first systematic neutronics study for the European DEMO divertor is reported. Results of the extensive assessment of key nuclear loading features (nuclear heating, irradiation damage & helium production) are presented for two optional concepts, namely, dome and shielding liner including minor geometrical variants. The shielding performance of the two competing design options is discussed together with the case of a bare cassette (no shielding), particularly in terms of damage dose compared with the design limits specified for the European DEMO.It was found that both the dome and shielding liner were able to significantly reduce the nuclear loads in the cassette body and the vessel. The maximum damage dose at the end of the lifetime remained subcritical for the cassette body for both cases whereas it exceeded the limit for the vessel under the dome, but only locally on the surface underneath the pumping duct. But, the damage could be reduced below the limit for the vessel by increasing the size of the dome or by deploying the shielding liner. The most critical feature was the excessive damage occurring in the own body of the shielding components where the maximum damage dose in the steel heat sink of the dome and the shielding liner far exceeded the design limit at the end of the lifetime

Systems engineering approach for pre-conceptual design of DEMO divertor cassette

Abstract This paper presents the pre-conceptual design activities conducted for the European DEMO divertor, focusing on cassette design and Plasma Facing Components (PFC) integration. Following the systems engineering principles, a systematic design method, the Iterative and Participative Axiomatic Design Process (IPADeP), has been adopted. Basing on Axiomatic Design, IPADeP supports the early conceptual design of complex systems. The work moved from the geometrical and interface constraints imposed by the 2015 DEMO configuration model. Then, since different materials will be used for cassette and PFCs, the divertor geometry has been developed taking into account the cooling parameters of the cassette Eurofer steel and the integration of PFCs cooling system. Accordingly, the design process led to a double wall cassette structure with internal reinforcing ribs to withstand cassette coolant pressure and three different kinds of piping schemes for PFCs with dual circuits. These three solutions differs in the feeding pipes layouts and target manifold protection and they have been proposed and evaluated considering heat flux issues, shielding problems, interface requirements with blanket and vacuum vessel and remote maintenance needs. A cassette parametric shell model has been used to perform first structural analyses of the cassette body against coolant pressure. Taking advantages of the parametric surface modelling and its linkage with Finite Element (FE) code, the cassette ribs layout and thickness has been evaluated and optimized, considering at the same time the structural strength needed to withstand the coolant parameters and the maximum stiffness required for cassette preloading and locking needs