622 research outputs found

    Radiation and magnetic field effects on new semiconductor power devices for HL-LHC experiments

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    The radiation hardness of commercial Silicon Carbide and Gallium Nitride power MOSFETs is presented in this paper, for Total Ionizing Dose effects and Single Event Effects, under gamma, neutrons, protons and heavy ions. Similar tests are discussed for commercial DC-DC converters, also tested in operation under magnetic field

    Accuracy of emergency physicians\u27 self-estimates of CT scan utilization and its potential effect on an audit and feedback intervention: a randomized trial

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    BACKGROUND: Audit and feedback (AandF) has been used as a strategy to modify clinician behavior with moderate success. Although AandF is theorized to work by improving the accuracy of clinicians\u27 estimates of their own behavior, few interventions have included assessment of clinicians\u27 estimates at baseline to examine whether they account for intervention success or failure. We tested an AandF intervention to reduce computed tomography (CT) ordering by emergency physicians, while also examining the physicians\u27 baseline estimates of their own behavior compared to peers. METHODS: Our study was a prospective, multi-site, 20-month, randomized trial to examine the effect of an AandF intervention on CT ordering rates, overall and by test subtype. From the electronic health record, we obtained 12 months of baseline CT ordering per 100 patients treated for every physician from four emergency departments. Those who were randomized to receive AandF were shown a de-identified graph of the group\u27s baseline CT utilization, asked to estimate wherein the distribution of their own CT order practices fell, and then shown their actual performance. All participants also received a brief educational intervention. CT ordering rates were collected for all physicians for 6 months after the intervention. Pre-post ordering rates were compared using independent and repeated measures t tests. RESULTS: Fifty-one of 52 eligible physicians participated. The mean CT ordering rate increased significantly in both experimental conditions after the intervention (intervention pre = 35.7, post = 40.3, t = 4.13, p \u3c 0.001; control pre = 33.9, post = 38.9, t = 3.94, p = 0.001), with no significant between-group difference observed at follow-up (t = 0.43, p = 0.67). Within the intervention group, physicians had poor accuracy in estimating their own ordering behavior at baseline: most overestimated and all guessed that they were in the upper half of the distribution of their peers. CT ordering increased regardless of self-estimate accuracy. CONCLUSIONS: Our AandF intervention failed to reduce physician CT ordering: our feedback to the physicians showed most of them that they had overestimated their CT ordering behavior, and they were therefore unlikely to reduce it as a result. After audit, it may be prudent to assess baseline clinician awareness of behavior before moving toward a feedback intervention

    HBIM MODELLING FOR THE ARCHITECTURAL VALORISATION VIA A MAINTENANCE DIGITAL ECO-SYSTEM

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    The present contribution falls within the framework of the actions envisaged by the "SMART Bethlehem – Sustainable Management And Renewal of Technology in the City of Bethlehem" (2022 – ongoing) research project, scientifically coordinated by the University of Pavia and co-founded by the Italian Agency for Cooperation and Development (AICS). Among the main objectives of the cooperation project is the sustainable urban and territorial development of the Bethlehem area by means of multi-scalar activities, mainly focusing on refurbishment and energy optimisation of a few relevant municipality buildings. A test case implementation of the HBIM methodology was then carried out on the Peace Center, an iconic building facing the "Manger Square" in close proximity to the "Nativity Church", aiming to validate the proposed systematisation of a scan-to-BIM approach focused on the development of an optimised data repository for the planned operation and maintenance activities. An ECO-Systemic workflow is presented, organised in five recursive steps. Starting from a SLAM-TLS integrated digital survey (3DS), the federated sub-models that comprise the overall project are geo-referenced (GEO) within a shared coordinate system (FSC) environment, thereby providing the basis for the subsequent architectural modelling of the built asset (ARC) and the associated enhancement of the level of information (LOI)

    The industrial applicability of PEA space charge measurements, for performance optimization of HVDC power cables

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    Cable manufacturing industries are constantly trying to improve the electrical performance of power cables. During the years, it was found that one of the most relevant degradation factors influencing the cable lifetime is the presence of space charge in the insulation layer. To detect the accumulated charge, the pulsed electro-acoustic (PEA) method is the most used technique. Despite the wide use of the PEA cell, several issues are still present. In particular, the PEA output signal is strongly disturbed by the acoustic waves reflections within the PEA cell. This causes the distortion of the output signal and therefore the misinterpretation of the charge profiles. This, in turn, may result in an incorrect cable characterization from the space charge phenomenon point of view. In 2017, due to the proved degradation effect of the space charge accumulation phenomenon, the IEEE Std 1732 was developed. This standard describes the steps to be followed for the space charge measurement in cables specimens during pre-qualification or type tests. Therefore, cable manufacturing industries started to take a particular interest in these measures. In the light of this, the aim of the present work is to highlight that the enacted standard is not easily applicable since various problems are still present in the PEA method for cables. In particular, in this work, the effect of multiple reflected signals due to the different interfaces involved, but also the effect of the signal attenuation due to cable dielectric thickness, as well as the effect of the PEA cell ground electrode thickness in the output charge profile, are reported. These issues have been demonstrated by means of an experimental test carried out on a full-size cable in the Prysmian Group High Voltage laboratory. To better understand the PEA cell output signal formation, a PEA cell model was developed in a previous work and it has been experimentally validated here. In particular, simulations have been useful to highlight the effect of the reflection phenomena due to the PEA cell ground electrode thickness on the basis of the specimen under test features. Moreover, by analyzing the simulation results, it was possible to separate the main signal from the reflected waves and, in turn, to calculate the suitable ground electrode thickness for the cable specimen under test

    Surface Periodic Poling in Lithium Niobate and Lithium Tantalate

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    Periodic Poling of Lithium Niobate crystals (PPLN) by means of electric field has revealed the best technique for finely tailoring PPLN structures and parameters, which play a central role in many current researches in the field of nonlinear integrated optics. Besides the most studied technique of bulk poling, recently a novel technique where domain inversion occurs just in a surface layer using photoresist or silica masks has been devised and studied. This surface periodic poling (SPP) approach is best suited when light is confined in a thin surface guiding layer or stripe, as in the case of optical waveguide devices. Also, we found that SPP respect to bulk poling offers two orders of magnitude reduction on the scale of periodicity, so that even nanostructures can be obtained provided an high resolution holographic mask writing technique is adopted. We were able to demonstrate 200 nm domain size, and also good compatibility with alpha-phase proton exchange channel waveguide fabrication. Our first experiments on Lithium Tantalate have also shown that the SPP technology appears to be applicable to this crystal (SPPLT), whose properties can allow to overcome limitations such as optical damage or UV absorption still present in PPLN devices. Finally, the issue of SPP compatibility with proton exchange waveguide fabrication will be addresse

    Relation between flood pulse and functional composition of the macroinvertebrate benthic fauna in the lower Rio Negro, Amazonas, Brazil

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    In a twelve-month study carried out at the archipelago of Anavilhanas, lower Rio Negro, State of Amazonas, Brazil, the macroinvertebrate fauna was sampled from the margins of a lake (Redondo lake) permanently connected to the river. The total biomass of the macroinvertebrates sampled during this period was 9,985.5 mg (dry weight) and 19,314 specimens were collected. Decapods (52.9 %) were the most important group regarding biomass while dipterans (21.1 %), ostracods (20.0%), cladocerans (14.0 %), and oligochaetes (13.4%) were the most abundant macroinvertebrates. All taxa showed frequency variations related to the high-low water cycle of Rio Negro and the substrate at the lake margins varied in quantity as well as in composition and structure. The greatest amounts of litter occurred in the flood period, with a higher proportion of new and whole leaves. The degree of litter fragmentation increased towards the low water period. The functional structure of the macroinvertebrate community showed adaptation to the available substrate in each season. A gradient of dominance between the functional categories, related to the distance from the central area of the water body, was observed. Shredders were sampled mainly inside the "igapó" (high water period), in a similar proportion to collectors. On the other hand, collectors were clearly predominant in the dry period. Scrapers were limited to the rising and falling water periods. The same trend is probably found in all the corresponding sections of the Rio Negro

    Fruit Development in Ficus carica L.: Morphological and Genetic Approaches to Fig Buds for an Evolution From Monoecy Toward Dioecy

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    The mechanism behind the bud evolution towards breba or main crop in Ficus carica L. is uncertain. Anatomical and genetic studies may put a light on the possible similarities/differences between the two types of fruits. For this reason, we collected complimentary data from anatomical, X-ray imaging, and genetic techniques. The RNA seq together with structural genome annotation allowed the prediction of 34,629 known genes and 938 novel protein-coding genes. Transcriptome analysis of genes during bud differentiation revealed differentially expressed genes in two fig varieties (Dottato and Petrelli) and in breba and main crop. We chose Dottato and Petrelli because the first variety does not require pollination to set main crop and the latter does; moreover, Petrelli yields many brebas whereas Dottato few. Of the 1,615 and 1,904 loci expressed in Dottato and Petrelli, specifically in breba or main crop, respectively, only 256 genes appeared to be transcripts in both varieties. The buds of the two fig varieties were observed under optical microscope and using 3D X-ray tomography, highlighting differences mainly related to the stage of development. The X-ray images of buds showed a great structural similarity between breba and main crop during the initial stages of development. Analysis at the microscope indicated that inflorescence differentiation of breba was split in two seasons whereas that of main crop started at the end of winter of season 2 and was completed within 2 to 3 months. The higher expression of floral homeotic protein AGAMOUS in breba with respect to main crop, since this protein is required for normal development of stamens and carpels in the flower, may indicate an original role of these fruits for staminate flowers production for pollination of the main crop, as profichi in the caprifig. Several genes related to auxin (auxin efflux carrier, auxin response factor, auxin binding protein, auxin responsive protein) and to GA synthesis (GA20ox) were highly expressed in brebas with respect to main crop for the development of this parthenocarpic fruit

    A methodology for assessing the impact of salinity gradient power generation in urban contexts

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    The paper proposes a methodology to assess the potential impact of salinity gradient power technology in urban contexts. The idea to employ such energy source in urban contexts derives from the observation that, among the energy districts outputs, low-salinity treated wastewater can be used to produce electricity if a suitable source of high salinity feed (seawater of a salt-works) is also available. The methodology uses the HOMER software for assessing the district’s electric energy production, consumption and exchange with the main grid. Then, starting from the total gross surface and the number of inhabitants of the district, some possible realistic scenarios characterized by different wastewater flow rate are defined. Finally, for each scenario the size and the yearly energy production of the salinity gradient power system are calculated thanks to a simulator carried out by the same authors. An application example, considering three different scenarios, shows that urban density plays a crucial role in the process and that the most promising realistic scenarios are those including treated wastewater and brine and unlimited seawater and brine. The economic feasibility of the salinity gradient power technology is evaluated by a comparison with classical renewable technologies such as photovoltaic and wind systems
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