Over the past two decades, both X-ray and gamma-ray astronomy have experienced great progress. However, the region of the electromagnetic spectrum around ∼1 MeV is not so thoroughly explored. Future ...medium-sized gamma-ray telescopes will fill this gap in observations. As the timescale for the development and launch of a medium-class mission is ∼10 years, with substantial costs, we propose a different approach for the immediate future. In this paper, we evaluate the viability of a much smaller and cheaper detector: a nano-satellite Compton telescope, based on the CubeSat architecture. The scientific performance of this telescope would be well below that of the instrument expected for the future larger missions; however, via simulations, we estimate that such a compact telescope will achieve a performance similar to that of COMPTEL.
Nano-satellite MeV telescope is becoming attractive nowadays. The dominant interaction mechanism of the electromagnetic spectrum around 1MeV is Compton scattering. However, the gamma-rays generated ...by primary particles hitting the atmosphere and the pair production events are the two significant background events when the satellite is operating in Low Earth Orbit. In this paper, we applied Machine Learning models to identify and reject the two troublesome background event types. Ensemble technique and imbalance solution are explored in order to obtain a better performance. Experiments demonstrated that the proposed methods can discriminate the pair events with a high accuracy, and the satellite’s sensitivity has also been improved dramatically.
In this work, we present some new results of the use of a full-wave time-domain numerical method for the realistic simulation of the response of an object buried in marine sediments. The directivity, ...as well as, the time response and the frequency response of an object with different levels of burial are calculated and compared showing how these responses are modified by the level of burial. This study can lead to improving the detection and identification of such buried objects.
Numerical simulators of the propagation of mechanical perturbations in heterogeneous media are an essential tool for numerous applications in underwater acoustics. Computing the evolution in time of ...acoustic and elastic waves traveling across fluid/solid boundaries is yet a challenging task. The study reported in this paper investigates the accuracy of various algorithms for the simulation of the two-dimensional propagation of a cylindrical pulse through a fluid/solid interface. Three solvers are employed for this numerical experiment: SPECFEM (Spectral Finite Element Method), a code based on a spectral-element method employing fourth-order polynomial basis functions; EFIT (Elastodynamic Finite Integration Technique), an algorithm based on a staggered second-order finite-difference time-domain method; ESIM-n (Explicit Simplified Interface Method), a solver which uses n th -order finite-differences and Runge-Kutta time integrators. Despite its simplicity, this benchmark allows ascertaining the ability of such algorithms to correctly handle the interfaces between different media, and evaluating the scheme resolutions in terms of points-per-wavelength.
In Industry 4.0 era, rapid changes to the global landscape of manufacturing are transforming industrial plants in increasingly more complex digital systems. One of the most impactful innovations ...generated in this context is the “Digital Twin”, a digital copy of a physical asset, which is used to perform simulations, health predictions and life cycle management through the use of a synchronized data flow in the manufacturing plant. In this paper, an innovative approach is proposed in order to contribute to the current collection of applications of Digital Twin in manufacturing: a Digital Shadow cloud-based application to enhance quality control in the manufacturing process. In particular, the proposal comprises a Digital Shadow updated on high performance computing cloud infrastructure in order to recompute the performance prediction adopting a variation of the computer-aided engineering model shaped like the actual manufactured part. Thus, this methodology could make possible the qualification of even not compliant parts, and so shift the focus from the compliance to tolerance requirements to the compliance to usage requirements. The process is demonstrated adopting two examples: the structural assessment of the geometry of a shaft and the one of a simplified turbine blade. Moreover, the paper presents a discussion about the implications of the use of such a technology in the manufacturing context in terms of real-time implementation in a manufacturing line and lifecycle management.
Accurate measures of species abundance are essential to identify conservation strategies. N-mixture models are increasingly used to estimate abundance on the basis of species counts. In this study we ...tested whether abundance estimates obtained using N-mixture models provide consistent results with more traditional approaches requiring capture (capture-mark recapture and removal sampling). We focused on endemic, threatened species of amphibians and reptiles in Italy, for which accurate abundance data are needed for conservation assessments: the Lanza's Alpine salamander Salamandra lanzai, the Ambrosi's cave salamander Hydromantes ambrosii and the Aeolian wall lizard Podarcis raffonei. In visual counts, detection probability was variable among species, ranging between 0.14 (Alpine salamanders) and 0.60 (cave salamanders). For all the species, abundance estimates obtained using N-mixture models showed limited differences with the ones obtained through capture-mark-recapture or removal sampling. The match was particularly accurate for cave salamanders in sites with limited abundance and for lizards, nevertheless non-incorporating heterogeneity of detection probability increased bias. N-mixture models provide reliable abundance estimates that are comparable with the ones of more traditional approaches, and offer additional advantages such as a smaller sampling effort and no need of manipulating individuals, which in turn reduces the risk of harming animals and spreading diseases.
Coastal areas are among the most biologically productive, dynamic and valued ecosystems on Earth. They are subject to changes that greatly vary in scale, time and duration and to additional pressures ...resulting from anthropogenic activities. The aim of this work was to investigate the shoreline evolution and the main environmental changes of the coastal stretch between the towns of Licata and Gela (in the Gulf of Gela, Sicily, Italy). The methodology used in this work included the analysis of: (i) shoreline changes over the long- and medium-term periods (1955–2019 and 1989–2019, respectively), (ii) dune system fragmentation and (iii) the impact of coastal structures (harbours and breakwaters) on coastal evolution. The shoreline change analysis mainly showed a negative trend both over the long- and medium-term periods, with a maximum retreat of 3.87 m/year detected over the medium-term period down-drift of the Licata harbour. However, a few kilometres eastward from the harbour, significant accretion was registered where a set of breakwaters was emplaced. The Shoreline Change Envelope (SCE) showed that the main depositional phenomena occurred during the decade between 1955 and 1966, whereas progressive and constant erosion was observed between 1966 and 1989 in response to the increasing coastal armouring.
Brunner’s gland hamartoma is a rare duodenal lesion. Resection for benign neoplasms of the duodenum should be considered in case of malignant potential or in case of symptomatic lesions. An accurate ...preoperative staging is mandatory in order to allow minimally invasive surgical approach, and to avoid under- or overtreatment. Endoscopic ultrasonography (EUS), Computed tomography (CT) scan, Magnetic Resonance Imaging (MRI) and PET/CT are techniques widely used for gastrointestinal tumor staging. We report a case of a 41-year-old female presenting a giant lesion of the second portion of the duodenum. Pathological examination of multiple forceps biopsies was inconclusive for histological characterization of the lesion. After a clinical staging including Esophagusgastroduodenoscopy, EUS, and CT scan, a Hybrid 18FDG PET/MRI was performed to assess the malignant potential of the lesion and the relation between polyp base and Vater’s papilla. After multidisciplinary meeting, the patient underwent robotic transduodenal excision. The post-operative course was uneventful, and the patient was discharged on post-operative day 5. Final pathologic report consists in a histologically of Brunner’s Glands Hamartoma. This is the first report on the role of 18FDG PET/MRI in staging and planning treatment of bulky low malignant duodenal lesion. An accurate staging with 18FDG PET/MRI could be very useful in the planning the management of duodenal lesion with uncertain malignant potential in order to avoid under- and overtreatment.
Brunner's gland hamartoma is a rare duodenal lesion. Resection for benign neoplasms of the duodenum should be considered in case of malignant potential or in case of symptomatic lesions. An accurate ...preoperative staging is mandatory in order to allow minimally invasive surgical approach, and to avoid under- or overtreatment. Endoscopic ultrasonography (EUS), Computed tomography (CT) scan, Magnetic Resonance Imaging (MRI) and PET/CT are techniques widely used for gastrointestinal tumor staging. We report a case of a 41-year-old female presenting a giant lesion of the second portion of the duodenum. Pathological examination of multiple forceps biopsies was inconclusive for histological characterization of the lesion. After a clinical staging including Esophagusgastroduodenoscopy, EUS, and CT scan, a Hybrid
FDG PET/MRI was performed to assess the malignant potential of the lesion and the relation between polyp base and Vater's papilla. After multidisciplinary meeting, the patient underwent robotic transduodenal excision. The post-operative course was uneventful, and the patient was discharged on post-operative day 5. Final pathologic report consists in a histologically of Brunner's Glands Hamartoma. This is the first report on the role of
FDG PET/MRI in staging and planning treatment of bulky low malignant duodenal lesion. An accurate staging with
FDG PET/MRI could be very useful in the planning the management of duodenal lesion with uncertain malignant potential in order to avoid under- and overtreatment.
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