Wave propagation in three-dimensional anelastic media: the modal summation method in the WKBJ-approximation

2007/2008In this thesis a new methodology for computing synthetic seismograms, complete of the main direct, refracted, converted phases and surface waves, in three – dimensional anelastic lateral heterogeneous media is presented. It is based on the combination of the Modal Summation technique with the Asymptotic Ray Theory. The three – dimensional models are determined by a set of vertically heterogeneous sections (1D structures) that are juxtaposed on a regular grid. The distribution of these sections in the grid is done in such a way to satisfy the condition of applicability of the WKBJ – approximation, i.e. the lateral variation of all the elastic parameters has to be small with respect to the prevailing wavelength. In each knot of the grid a vertically heterogeneous section is located, hence, the values of the phase velocities, of the phase attenuation and of the group velocities are assigned once and for all. Inside the grid the source and the receiver are located, assigning their coordinates by means of a Cartesian reference system introduced in the grid itself. By this way a vertically heterogeneous structure, hence one-dimensional structure, is associated to the source and another to the receiver. The eigenfunctions of these two structures do contribute to the seismogram. The computational scheme is based, besides on the WKBJ - approximation for weak lateral heterogeneities, on the two point ray – tracing algorithm, by means of the bi - dimensional shooting method. It can be summarized as follows: at first the ray connecting two points, the source and the receiver, is computed solving the Cauchy problem for the system of ordinary differential equations governing the phenomenon of the evolution of the ray itself; the system is solved employing the numerical fourth – order Runge – Kutta method. Once the ray is determined, the attenuation is computed along it, solving, once again using the fourth – order Runge – Kutta method, the Cauchy problem for a system of ordinary differential equations that is made up of four equations: three equations for the ray and one equation governing the evolution of the attenuation along the ray itself. Finally, the geometrical spreading is computed considering two more rays that leave the source with an azimuth that is determined increasing and decreasing the azimuth of the characteristic curve of the ray – tracing system (the true ray) by a fixed quantity. The thesis is divided in two main parts, the first contains a theoretical treatment of the above mentioned arguments, so it opens with a brief summary about the generation of synthetic seismograms in one-dimensional structures by mean of the Modal Summation technique and goes on with the introduction of the WKBJ – approximation for treating the lateral heterogeneities. Then, there is the presentation of the numerical procedure used in this work. The second part is devoted to the validation of the new method, so the simulations executed to this aim are shown. It is very important to stress that the computational codes used in this work are still under development. They will be used for verifying and optimizing the results up to now obtained, both in terms of seismic sources and in terms of structural models, in region of the Scotia Arc.In questa tesi si presenta una nuova metodologia per il calcolo di sismogrammi sintetici completi delle principali fasi dirette, rifratte, convertite ed onde superficiali in mezzi tridimensionali anelastici lateralmente eterogenei, basata sulla Somma Modale (SM) combinata con la Teoria Asintotica dei Raggi (TAR). I modelli tridimensionali sono determinati da un insieme di sezioni verticalmente eterogenee (strutture 1D) che vengono affiancate su una griglia regolare. La distribuzione di dette sezioni nella griglia e’ tale da soddisfare la condizione di applicabilità della approssimazione WKBJ (acronimo dei nomi dei quattro elaboratori della metodologia: Wentzel, Kramers, Brillouin and Jeffreys), cioè la variazione laterale di tutti i parametri elastici deve essere piccola rispetto alle lunghezze d’onda prevalenti. In ogni nodo della griglia e’ collocata una sezione verticalmente eterogenea, sono, quindi, assegnati una volta per tutte i valori della velocità di fase, dell’attenuazione di fase e della velocità di gruppo. All’interno della griglia si collocano la sorgente ed il ricevitore, assegnando le loro coordinate attraverso un sistema cartesiano di riferimento introdotto nella griglia stessa. In questo modo si associa una struttura verticalmente eterogenea, quindi unidimensionale, alla sorgente ed una al ricevitore. Le autofunzioni di queste due strutture contribuiscono al sismogramma. Lo schema computazionale è basato, oltre che sull’approssimazione WKBJ per eterogeneità laterali deboli, sull’algoritmo per il ray-tracing tra due punti, mediante lo shooting-method bidimensionale. Esso può essere riassunto come segue: dapprima si calcola il raggio che unisce i due punti, la sorgente ed il ricevitore, risolvendo il problema di Cauchy per il sistema di equazioni differenziali alle derivate ordinarie che governa il fenomeno dell’evoluzione del raggio stesso; il sistema è risolto per via numerica mediante il metodo di Runge-Kutta del quarto ordine. Una volta che il raggio è determinato, si calcola lungo esso l’attenuazione, risolvendo, ancora una volta mediante il metodo di Runge-Kutta del quarto ordine, il problema di Cauchy per un sistema di equazioni differenziali alle derivate ordinarie che è costituito dal sistema che governa l’evoluzione del raggio più una quarta equazione che governa l’evoluzione dell’attenuazione lungo il raggio stesso. Infine, il geometrical spreading è calcolato considerando due ulteriori raggi che partono dalla sorgente con un azimuth 5 che è determinato aumentando e diminuendo l’azimuth della curva caratteristica del sistema (raggio vero) di un valore fissato. La tesi è divisa in due parti principali, la prima parte contiene una trattazione teorica degli argomenti precedentemente menzionati, si apre quindi con un breve riassunto sulla generazione di sismogrammi sintetici in strutture unidimensionali mediante la tecnica della Somma Modale e prosegue con l’introduzione dell’approssimazione WKBJ per la trattazione delle eterogeneità laterali. Si passa poi alla presentazione della procedura numerica utilizzata. La seconda parte è dedicata alla validazione del nuovo metodo, dunque sono presentate le simulazioni eseguite a questo scopo. E’ da sottolineare che i codici di calcolo utilizzati, attentamente testati e ripetutamente validati, sono in continuo sviluppo. Essi verranno utilizzati per la verifica e l’ottimizzazione dei risultati fin qui conseguiti, sia in termini di sorgenti sismiche che di modelli strutturali, nella regione dell’Arco di Scotia.XXI Ciclo197

Total area of spontaneous portosystemic shunts independently predicts hepatic encephalopathy and mortality in liver cirrhosis

Background & Aims: Spontaneous portosystemic shunts (SPSS) frequently develop in liver cirrhosis. Recent data suggested that the presence of a single large SPSS is associated with complications, especially overt hepatic encephalopathy (oHE). However, the presence of >1 SPSS is common. This study evaluates the impact of total cross-sectional SPSS area (TSA) on outcomes in patients with liver cirrhosis. Methods: In this retrospective international multicentric study, CT scans of 908 cirrhotic patients with SPSS were evaluated for TSA. Clinical and laboratory data were recorded. Each detected SPSS radius was measured and TSA calculated. One-year survival was the primary endpoint and acute decompensation (oHE, variceal bleeding, ascites) was the secondary endpoint. Results: A total of 301 patients (169 male) were included in the training cohort. Thirty percent of all patients presented with >1 SPSS. A TSA cut-off of 83 mm2 was used to classify patients with small or large TSA (S-/L-TSA). Patients with L-TSA presented with higher model for end-stage liver disease score (11 vs. 14) and more commonly had a history of oHE (12% vs. 21%, p <0.05). During follow-up, patients with L-TSA experienced more oHE episodes (33% vs. 47%, p <0.05) and had lower 1-year survival than those with S-TSA (84% vs. 69%, p <0.001). Multivariate analysis identified L-TSA (hazard ratio 1.66; 95% CI 1.02–2.70, p <0.05) as an independent predictor of mortality. An independent multicentric validation cohort of 607 patients confirmed that patients with L-TSA had lower 1-year survival (77% vs. 64%, p <0.001) and more oHE development (35% vs. 49%, p <0.001) than those with S-TSA. Conclusion: This study suggests that TSA >83 mm2 increases the risk for oHE and mortality in patients with cirrhosis. Our results support the clinical use of TSA/SPSS for risk stratification and decision-making in the management of patients with cirrhosis. Lay summary: The prevalence of spontaneous portosystemic shunts (SPSS) is higher in patients with more advanced chronic liver disease. The presence of more than 1 SPSS is common in advanced chronic liver disease and is associated with the development of hepatic encephalopathy. This study shows that total cross-sectional SPSS area (rather than diameter of the single largest SPSS) predicts survival in patients with advanced chronic liver disease. Our results support the clinical use of total cross-sectional SPSS area for risk stratification and decision-making in the management of SPSS.Jonel Trebicka is supported by grants from the Deutsche Forschungsgemeinschaft (SFB TRR57, CRC1382), Cellex Foundation and European Union’s Horizon 2020 research and innovation program GALAXY study (No. 668031), LIVERHOPE (No. 731875) and MICROB-PREDICT (No. 825694) and the Cellex Foundation. Joan Genescà is a recipient of a Research Intensification grant from Instituto de Salud Carlos III, Spain. The study was partially funded by grants PI15/00066, and PI18/00947 from Instituto de Salud Carlos III and co-funded by European Union (ERDF/ESF, “Investing in your future”). Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivasis supported by Instituto de Salud Carlos III. Macarena Simón-Talero is a recipient of the grant JR 17/00029 from Instituto de Salud Carlos II

Genetic determinants in a critical domain of ns5a correlate with hepatocellular carcinoma in cirrhotic patients infected with hcv genotype 1b

HCV is an important cause of hepatocellular carcinoma (HCC). HCV NS5A domain‐1 interacts with cellular proteins inducing pro‐oncogenic pathways. Thus, we explore genetic variations in NS5A domain‐1 and their association with HCC, by analyzing 188 NS5A sequences from HCV genotype‐1b infected DAA‐naïve cirrhotic patients: 34 with HCC and 154 without HCC. Specific NS5A mutations significantly correlate with HCC: S3T (8.8% vs. 1.3%, p = 0.01), T122M (8.8% vs. 0.0%, p < 0.001), M133I (20.6% vs. 3.9%, p < 0.001), and Q181E (11.8% vs. 0.6%, p < 0.001). By multivariable analysis, the presence of >1 of them independently correlates with HCC (OR (95%CI): 21.8 (5.7–82.3); p < 0.001). Focusing on HCC‐group, the presence of these mutations correlates with higher viremia (median (IQR): 5.7 (5.4–6.2) log IU/mL vs. 5.3 (4.4–5.6) log IU/mL, p = 0.02) and lower ALT (35 (30–71) vs. 83 (48–108) U/L, p = 0.004), suggesting a role in enhancing viral fitness without affecting necroinflammation. Notably, these mutations reside in NS5A regions known to interact with cellular proteins crucial for cell‐cycle regulation (p53, p85‐PIK3, and β‐ catenin), and introduce additional phosphorylation sites, a phenomenon known to ameliorate NS5A interaction with cellular proteins. Overall, these results provide a focus for further investigations on molecular bases of HCV‐mediated oncogenesis. The role of these NS5A domain‐1 mutations in triggering pro‐oncogenic stimuli that can persist also despite achievement of sustained virological response deserves further investigation

Predicting needlestick and sharps injuries in nursing students: Development of the SNNIP scale

© 2020 The Authors. Nursing Open published by John Wiley & Sons Ltd. Aim: To develop an instrument to investigate knowledge and predictive factors of needlestick and sharps injuries (NSIs) in nursing students during clinical placements. Design: Instrument development and cross-sectional study for psychometric testing. Methods: A self-administered instrument including demographic data, injury epidemiology and predictive factors of NSIs was developed between October 2018–January 2019. Content validity was assessed by a panel of experts. The instrument's factor structure and discriminant validity were explored using principal components analysis. The STROBE guidelines were followed. Results: Evidence of content validity was found (S-CVI 0.75; I-CVI 0.50–1.00). A three-factor structure was shown by exploratory factor analysis. Of the 238 participants, 39% had been injured at least once, of which 67.3% in the second year. Higher perceptions of “personal exposure” (4.06, SD 3.78) were reported by third-year students. Higher scores for “perceived benefits” of preventive behaviours (13.6, SD 1.46) were reported by second-year students

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

3- Dimensional Modal Summation simulation of 2003 Mw=6.6 Bam Earthquake South Eastern Iran

A new methodology for computing synthetic seismograms, complete of the main direct, refracted, converted phases and surface waves, in three \u2013 dimensional anelastic lateral heterogeneous media is applied to the modeling of the local records of the 2003 Bam Mw 6.6 Earthquake, South-Eastern Iran. The method is based on the combination of the Modal Summation (MS) technique with the Asymptotic Ray Theory (ART). The three \u2013 dimensional models are determined by a set of vertically heterogeneous sections (1D structures) that are juxtaposed on a regular grid. The distribution of these sections in the grid is done in such a way to satisfy the condition of applicability of the WKBJ approximation, i.e. the lateral variation of all the elastic parameters has to be small with respect to the prevailing wavelength. The procedure, described very briefly, has been applied for the area of destructive 26 December 2003 Bam earthquake Mw= 6.6

Seismic Hazard Scenarios as Preventive Tools for a Disaster Resilient Society

Lessons learnt from the destructive earthquakes occurred during the new millennium provide new opportunities to take action, revise, and improve the procedure for seismic hazard assessment (SHA). A single hazard map cannot meet the requirements from different end-users; the mapping of the expected earthquake ground motion that accounts for events\u2019 recurrence may be suitable for insurances. When dealing with cultural heritage and critical structures (e.g., nuclear power plants), where it is necessary to consider extremely long time intervals, the standard hazard estimates are by far unsuitable, due to their basic heuristic limitations. While time-dependent SHA may be suitable to increase earthquake preparedness, by planning adequate mitigation actions, for critical structures (i.e., those for which the consequences of failure are intolerable) the maximum possible seismic input is relevant. Therefore the need for an appropriate estimate of the seismic hazard, aimed not only at the seismic classification of the national territory, but also at the capability of properly accounting for the local ampli\u2423cations of ground shaking, as well as for the fault properties, is a pressing concern for seismic engineers. A viable alternative to traditional SHA is represented by the use of the scenario earthquakes, characterized at least in terms of magnitude, distance, and faulting style, and by the treatment of complex source processes. The relevance of the realistic modeling, which permits the generalization of empirical observations by means of physically sound theoretical considerations, is evident, as it allows the optimization of the structural design with respect to the site of interest. The time information associated with the scenarios of ground motion, given by the intermediate-term middle-range earthquake predictions, can be useful to public authorities in assigning priorities for timely mitigation actions. Therefore, the approach we have developed naturally supplies realistic time series of ground motion useful to preserve urban settings, historical monuments, and relevant man-made structures