355 research outputs found
Broad-band near-field ground motion simulations in 3-dimensional scattering media
The heterogeneous nature of Earth's crust is manifested in the scattering of propagating seismic waves. In recent years, different techniques have been developed to include such phenomenon in broad-band ground-motion calculations, either considering scattering as a semi-stochastic or purely stochastic process. In this study, we simulate broad-band (0-10Hz) ground motions with a 3-D finite-difference wave propagation solver using several 3-D media characterized by von Karman correlation functions with different correlation lengths and standard deviation values. Our goal is to investigate scattering characteristics and its influence on the seismic wavefield at short and intermediate distances from the source in terms of ground motion parameters. We also examine scattering phenomena, related to the loss of radiation pattern and the directivity breakdown. We first simulate broad-band ground motions for a point-source characterized by a classic ω2 spectrum model. Fault finiteness is then introduced by means of a Haskell-type source model presenting both subshear and super-shear rupture speed. Results indicate that scattering plays an important role in ground motion even at short distances from the source, where source effects are thought to be dominating. In particular, peak ground motion parameters can be affected even at relatively low frequencies, implying that earthquake ground-motion simulations should include scattering also for peak ground velocity (PGV) calculations. At the same time, we find a gradual loss of the source signature in the 2-5Hz frequency range, together with a distortion of the Mach cones in case of super-shear rupture. For more complex source models and truly heterogeneous Earth, these effects may occur even at lower frequencies. Our simulations suggests that von Karman correlation functions with correlation length between several hundred metres and few kilometres, Hurst exponent around 0.3 and standard deviation in the 5-10percent range reproduce the available observation
Sensitivity of broad-band ground-motion simulations to earthquake source and Earth structure variations: an application to the Messina Straits (Italy)
In this paper, we investigate ground-motion variability due to different faulting approximations and crustal-model parametrizations in the Messina Straits area (Southern Italy). Considering three 1-D velocity models proposed for this region and a total of 72 different source realizations, we compute broad-band (0-10 Hz) synthetics for Mw 7.0 events using a fault plane geometry recently proposed. We explore source complexity in terms of classic kinematic (constant rise-time and rupture speed) and pseudo-dynamic models (variable rise-time and rupture speed). Heterogeneous slip distributions are generated using a Von Karman autocorrelation function. Rise-time variability is related to slip, whereas rupture speed variations are connected to static stress drop. Boxcar, triangle and modified Yoffe are the adopted source time functions. We find that ground-motion variability associated to differences in crustal models is constant and becomes important at intermediate and long periods. On the other hand, source-induced ground-motion variability is negligible at long periods and strong at intermediate-short periods. Using our source-modelling approach and the three different 1-D structural models, we investigate shaking levels for the 1908 Mw 7.1 Messina earthquake adopting a recently proposed model for fault geometry and final slip. Our simulations suggest that peak levels in Messina and Reggio Calabria must have reached 0.6-0.7 g during this earthquak
The role of haptic feedback in video-Assisted thoracic surgery simulation training
technological advances on haptic devices, together with further studies focused on haptic feedback, be useful to develop efficient and effective training curricula and for establishing the value of simulators with haptic feedback in training and assessing thoracic surgical skills
Evaluating the Factor Structure of the Emotion Dysregulation Scale-Short (EDS-s): A Preliminary Study
Emotion dysregulation (ED) can be considered a psychopathological transdiagnostic dimension, the presence of which should be reliably screened in clinical settings. The aim of the current study was to validate the Italian version of the Emotion Dysregulation Scale-short (EDS-s), a brief self-report tool assessing emotion dysregulation, in a non-clinical sample of 1087 adults (768 women and 319 men). We also assessed its convergent validity with scales measuring binge eating and general psychopathology. Structural equation modeling suggested the fit of a one-factor model refined with correlations between the errors of three pairs of items (χ2 = 255.56, df = 51, p < 0.001, RMSEA = 0.08, CFI = 0.94, TLI = 0.93, SRMR = 0.04). The EDS-s demonstrated satisfactory internal consistency (ordinal alpha = 0.94). Moreover, EDS-s scores partly explained the variance of both binge eating (0.35, p < 0.001) and general psychopathology (0.60, p < 0.001). In conclusion, the EDS-s can be considered to be a reliable and valid measure of ED
Bullous lung disease and neurofibromatosis type-1.
Lung interstitial diseases and bullae are described as possible complications of neurofibromatosis type-1 (NF-1), a genetic disorder inherited as a autosomal-dominant trait. We report the case of a 16-year-old male non-smoker with NF-1, who presented with pneumothorax caused by ruptured lung bullae. The case of this young patient, successfully treated by video-assisted thoracoscopic resection of bullae, supports the concept that pulmonary alterations may be part of the NF-1 syndrome, rather than as an unrelated complication
Bullous lung disease and neurofibromatosis type-1
Lung interstitial diseases and bullae are described as possible complications of neurofibromatosis type-1 (NF-1), a genetic disorder inherited as a autosomal-dominant trait. We report the case of a 16-year-old male non-smoker with NF-1, who presented with pneumothorax caused by ruptured lung bullae. The case of this young patient, successfully treated by video-assisted thoracoscopic resection of bullae, supports the concept that pulmonary alterations may be part of the NF-1 syndrome, rather than as an unrelated complication
STOCHASTIC AND FULL-WAVEFIELD FINITE-FAULT GROUND-MOTION SIMULATIONS OF THE M7.1, MESSINA 1908 EARTHQUAKE (Southern Italy)
In the framework of an ongoing Italian national research project we are studying the Messina 1908 earthquake, the first to be recorded adequately by seismological and geodetic instrumentation that allowed subsequent quantitative investigations of its source properties.
We use a high-frequency stochastic finite-fault modeling (Motazedian and Atkinson, 2005) to simulate the ground-shaking for a number of different source models (Basili et al. 2008), either constrained from past source studies of this event or simulated. Although inherently kinematic, our approach accounts for the physics of the source using a procedure to generate physically consistent earthquake-rupture models (Guatteri et al., 2004). Considering the width of the seismogenic zone and appropriate source-scaling relation, we generate heterogeneous slip models that obey to the source complexity of past earthquakes (Mai and Beroza, 2002). By also constraining the point of rupture initiation based on empirical findings and energy-balance arguments (Mai et al., 2005), we generate a suite of earthquake source models to compute far-field ground-shaking. The Housner parameter from the stochastic high-frequency simulations is than compared with the felt intensity (MCS scale). The developed procedure is a necessary tool to take into account the influence of directivity effects in simulating ground shaking scenarios using realistic slip distribution on the fault.
Furthermore, we carry out full-wavefield ground-motion calculations (at frequencies f < 3 Hz) to compare those low-frequency simulations with (a) the stochastic simulations and (b) appropriate ground-motion prediction equations. The combined approach helps to examine the validation range of the two methods (distinguishing the influence of the near-field and far-field motions on the shaking level), and may serve as a basis to develop a hybrid technique which combines the two methods for generating fully broadband synthetic seismograms
Deliverable 2 # A3.13.8
We examine possibilities to delineate the boundaries between near-field and far-field radiation of seismic waves. Near-field (NF), intermediate-field (IF) and far-field (FF) terms represent different properties of the seismic wave-field: the near-source motions are sensitive to the spatio-temporal details of the rupture process, while far-field terms tend to carry the overall signature of the rupture. Due to the longer propagation path of far-field waves through complex Earth structure, their waveform properties also depend more strongly on media properties (scattering; intrinsic attenuation), than it is the case for the NF-wavefield
Neurocognitive and Psychopathological Predictors of Weight Loss After Bariatric Surgery: A 4-Year Follow-Up Study
Twenty to thirty percent of patients experience weight regain at mid and long-term follow- up. Impaired cognitive functions are prevalent in people suffering from obesity and in those with binge eating disorder, thereby, affecting the weight-loss outcomes. The aim of our study was to investigate neurocognitive and psychopathological predictors of surgical efficacy in terms of percentage of excess weight loss (%EWL) at follow-up intervals of one year and 4-year. Psychosocial evaluation was completed in a sample of 78 bariatric surgery candidates and included psychometric instruments and a cognitive battery of neuropsychological tests. A schedule of 1-year and 4-year follow-ups was implemented. Wisconsin Sorting Card Test total correct responses, scores on the Raven’s Progressive Matrices Test, and age predicted %EWL at, both, early and long-term periods after surgery while the severity of pre-operative binge eating (BED) symptoms were associated with lower %EWL only four years after the operation. Due to the role of pre-operative BED in weight loss maintenance, the affected patients are at risk of suboptimal response requiring ongoing clinical monitoring, and psychological and pharmacological interventions when needed. As a result of our findings and in keeping with the latest guidelines we encourage neuropsychological assessment of bariatric surgery candidates. This data substantiated the rationale of providing rehabilitative interventions tailored to cognitive domains and time specific to the goal of supporting patients in their post-surgical course
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