87 research outputs found

    The Role of Soil and Site Conditions in the Vulnerability and Risk Assessment of Lifelines and Infrastructures. The Case of Thessaloniki (Greece).

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    Soil conditions and site effects play an important role in the vulnerability assessment of lifelines and infrastructures under strong seismic excitation. Due to the spatial extent of these networks, they are subjected to non-uniform and incoherent ground motion as a result of the variability of soil and geological conditions; consequently their vulnerability assessment depends entirely on the variability of soil conditions and ground motion, known as site effects, for a given seismic scenario. Fragility functions for the exposed elements at risk, composing the different lifelines and infrastructure systems, play an equally important role. The paper presents some selected results of a recent application of a comprehensive methodology assessing the vulnerability of several lifeline systems in Thessaloniki in Greece. The work is part of a large research program, aiming to the development of a general methodology for the assessment of the seismic risk for the building stock, lifeline systems and infrastructures at urban scale. Key factors of the methodology are the inventory, the typology, the specific characteristics and the importance (global value) of the elements at risk, the development of seismic scenarios (seismic hazard) and the geotechnical characterization, with the detailed site response analysis. The methodology and the role of soil and site conditions are highlighted with representative examples of the application in Thessaloniki

    Solar Energetic Particles in the Inner Heliosphere: Status and Open Questions

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    Solar energetic particle (SEP) events are related to both solar flares and coronal mass ejections (CMEs) and they present energy spectra that span from a few keV up to several GeV. A wealth of observations from widely distributed spacecraft have revealed that SEPs fill very broad regions of the heliosphere, often all around the Sun. High energy SEPs can sometimes be energetic enough to penetrate all the way down to the surface of the Earth and thus be recorded on the ground as ground level enhancements (GLEs). The conditions of the radiation environment are currently unpredictable due to an as-yet incomplete understanding of solar eruptions and their corresponding relation to SEP events. This is because the complex nature and the interplay of the injection, acceleration and transport processes undergone by the SEPs in the solar corona and the interplanetary space prevent us from establishing an accurate understanding (based on observations and modelling). In this work, we review the current status of knowledge on SEPs, focusing on GLEs and multi-spacecraft events. We extensively discuss the forecasting and nowcasting efforts of SEPs, dividing these into three categories. Finally, we report on the current open questions and the possible direction of future research efforts. This article is part of the theme issue Solar eruptions and their space weather impact

    Incidental giant renal oncocytoma: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Large renal oncocytomas are not very rare entities. To the best of our knowledge, we report one of the largest oncocytomas in the English literature. The tumor was incidentally diagnosed and, based on the preoperative clinical and radiographic findings, was therefore considered to be a renal cell carcinoma.</p> <p>Case presentation</p> <p>A 48-year-old Caucasian diabetic man had an abdominal ultrasound for chronic abdominal discomfort, which revealed a large mass on the left kidney. An abdominal computed tomography scan revealed a contrast enhancing, well defined, heterogenous large mass (16.5 × 13.9 cm) originating from the left lower pole with cystic and solid areas. A magnetic resonance imaging scan was performed with no evidence of renal vein or caval thrombus or embolus. A radical nephrectomy was performed through a left flank intercostal incision and the pathology diagnosed renal oncocytoma. The postoperative course was uneventful and the patient was discharged six days later.</p> <p>Conclusion</p> <p>Several reports have characterised this essentially benign renal histiotype, which represents 5% to 7% of all solid renal masses. Unfortunately, most renal oncocytomas cannot be differentiated from malignant renal cell carcinomas by clinical or radiographic criteria. Central stellate scar and a spoke-wheel pattern of feeding arteries are unreliable diagnostic signs and are of poor predictive value. These tumors are treated operatively with radical or partial nephrectomy or thermal ablation, depending on the clinical circumstances. We report on, to the best of our knowledge, the fourth largest lesion of this type of renal pathology.</p

    Prediction of solar proton event fluence spectra from their peak flux spectra

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    Solar Proton Events (SPEs) are of great importance and significance for the study of Space Weather and Heliophysics. These populations of protons are accelerated at high energies ranging from a few MeVs to hundreds of MeVs and can pose a significant hazard both to equipment on board spacecrafts as well as astronauts as they are ionizing radiation. The ongoing study of SPEs can help to understand their characteristics, relative underlying physical mechanisms, and help in the design of forecasting and nowcasting systems which provide warnings and predictions. In this work, we present a study on the relationships between the Peak Flux and Fluence spectra of SPEs. This study builds upon existing work and provides further insights into the characteristics and the relationships of SPE Peak flux and Fluence spectra. Moreover it is shown how these relationships can be quantified in a sound manner and exploited in a simple methodology with which the Fluence spectrum of an SPE can be well predicted from its given Peak spectrum across two orders of magnitude of proton energies, from 5 MeV to 200 MeV. Finally it is discussed how the methodology in this work can be easily applied to forecasting and nowcasting systems

    The probabilistic solar particle event forecasting (PROSPER) model

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    The Probabilistic Solar Particle Event foRecasting (PROSPER) model predicts the probability of occurrence and the expected peak flux of solar energetic particle (SEP) events. Predictions are derived for a set of integral proton energies (i.e., E > 10, > 30, and > 100 MeV) from characteristics of solar flares (longitude, magnitude), coronal mass ejections (width, speed), and combinations of both. Herein the PROSPER model methodology for deriving the SEP event forecasts is described, and the validation of the model, based on archived data, is presented for a set of case studies. The PROSPER model has been incorporated into the new operational advanced solar particle event casting system (ASPECS) tool to provide nowcasting (short term forecasting) of SEP events as part of ESA's future SEP advanced warning system (SAWS). ASPECS also provides the capability to interrogate PROSPER for historical cases via a run-on-demand functionality

    Transforming urinary stone disease management by artificial intelligence-based methods: A comprehensive review

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    Objective: To provide a comprehensive review on the existing research and evi-dence regarding artificial intelligence (AI) applications in the assessment and management of urinary stone disease.Methods: A comprehensive literature review was performed using PubMed, Scopus, and Google Scholar databases to identify publications about innovative concepts or supporting applica-tions of AI in the improvement of every medical procedure relating to stone disease. The terms "endourology", "artificial intelligence", "machine learning", and "urolithiasis"were used for searching eligible reports, while review articles, articles referring to automated procedures without AI application, and editorial comments were excluded from the final set of publica-tions. The search was conducted from January 2000 to September 2023 and included manu-scripts in the English language.Results: A total of 69 studies were identified. The main subjects were related to the detection of urinary stones, the prediction of the outcome of conservative or operative management, the optimization of operative procedures, and the elucidation of the relation of urinary stone chemistry with various factors.Conclusion: AI represents a useful tool that provides urologists with numerous amenities, which explains the fact that it has gained ground in the pursuit of stone disease management perfection. The effectiveness of diagnosis and therapy can be increased by using it as an alter-native or adjunct to the already existing data. However, little is known concerning the poten-tial of this vast field. Electronic patient records, containing big data, offer AI the opportunity to develop and analyze more precise and efficient diagnostic and treatment algorithms. Never-theless, the existing applications are not generalizable in real-life practice, and high-quality studies are needed to establish the integration of AI in the management of urinary stone dis-ease.CNN ; CNN
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