323,266 research outputs found
Multiparameter Full-Waveform Inversion for Velocity and Attenuation – Refining the Imaging of a Sedimentary Basin
No full textInternational audienceP276 Multiparameter Full-Waveform Inversion for Velocity and Attenuation – Refining the Imaging of a Sedimentary Basin M. Malinowski* (Institute of Geophysics PAS) A. Ribodetti (Geosciences Azur CNRS UMR) & S. Operto (Geosciences Azur CNRS UMR) SUMMARY This study deals with the extension of the frequency-domain full-waveform inversion/modelling (FWI) from the acoustic to the viscoacoustic case in application to the wide-aperture seismic data recorded in the Polish Basin. Attenuation was accounted for by introduction of complex velocities. Multiparameter inversion involving P-wave velocity and Q factor produces more focused and clearer images than obtained by the acoustic FWI however only the absorption ..
Finite-Difference Frequency-Domain Modeling of Acoustic Wave Propagation in 2D TTI Anisotropic Media
No full textInternational audienceP323 Finite-Difference Frequency-Domain Modeling of Acoustic Wave Propagation in 2D TTI Anisotropic Media M. Grini* (Géosciences Azur - CNRS) A. Ribodetti (Géosciences Azur - IRD) J. Virieux (Géosciences Azur - UNSA) & S. Operto (Geosciences Azur - CNRS) SUMMARY We present a 2D finite-difference frequency-domain method for modeling acoustic wave propagation in TTI media. The numerical method relies on a parsimonious staggered-grid method implemented in the frequency domain. Discretization of the differential operators is performed along 45° rotated directions. We applied this discretization strategy to the anisotropic acoustic wave equation for TTI media derived by Zhou (2006). The finite-difference stencil ..
Viscoacoustic Frequency-Domain Full-Waveform Inversion – Application to Numerical VSP Data
No full textInternational audienceC029 Viscoacoustic Frequency-Domain Full-Waveform Inversion – Application to Numerical VSP Data A. Ribodetti* (Geosciences Azur) R.E. Plessix (Shell) S. Operto (Geosciences Azur - CNRS) & J.M. Virieux (Geosciences Azur) SUMMARY This work presents numerical tests to show that viscoacoustic frequency-domain full waveform tomographic inversion can be a useful tool for velocity and attenuation Q factor estimates from Vertical Seismic Profiles data. EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 EAGE 69 th Conference & Exhibition — London UK 11 - ..
Viscoacoustic Frequency-Domain Full-Waveform Inversion – Application to Numerical VSP Data
No full textInternational audienceC029 Viscoacoustic Frequency-Domain Full-Waveform Inversion – Application to Numerical VSP Data A. Ribodetti* (Geosciences Azur) R.E. Plessix (Shell) S. Operto (Geosciences Azur - CNRS) & J.M. Virieux (Geosciences Azur) SUMMARY This work presents numerical tests to show that viscoacoustic frequency-domain full waveform tomographic inversion can be a useful tool for velocity and attenuation Q factor estimates from Vertical Seismic Profiles data. EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 EAGE 69 th Conference & Exhibition — London UK 11 - ..
Monitoring and managing depression in adolescents with epilepsy: Current perspectives
No full textEpilepsy is associated with a significantly increased risk of developing depressive disorder during adolescence. On the other hand, depression is highly detected in adolescents with epilepsy. These findings highlight the importance of early identification and proper management of comorbid depression in adolescent age. The prevalence of depressive disorders in adolescents with epilepsy ranges between 8 and 35% and is higher than the general population of the same age. The relationship between epilepsy and depression is complex and potentially bidirectional, thereby suggesting a common underlying pathophysiology. Furthermore, failure to detect and treat depressive disorder mostly in adolescence could lead to several negative implications such as an increased risk of suicidal ideation or behavior and poor quality of life. A number of methods are available to detect depressive disorder, such as psychiatric or psychological assessments, structured or semi-structured interviews, and self-report screening tools. Thus, physicians should be able to regularly screen depressive symptoms in youths with epilepsy. Recently, the NDDI-E-Y inventory has been developed from the adult NDDI-E, and has been validated in many countries. NDDI-E-Y has showed reliable validity, being a brief screening tool (12 items) that can be easily included in routine epilepsy care. The first step to be considered for the management of depressive disorder in adolescents with epilepsy is to consider potential reversible causes of anxiety and depression (i.e., a new AEDs; seizure control). Secondly, great attention has to be given to the education of the child/adolescent and his/her family, trying to improve knowledge about epilepsy as well as to decrease parental stress and improving the child's sense of competence. Pharmacological treatment should also be considered in adolescents diagnosed with depression
Finite-Difference Frequency-Domain Modeling of Acoustic Wave Propagation in 2D TTI Anisotropic Media
No full textInternational audienceP323 Finite-Difference Frequency-Domain Modeling of Acoustic Wave Propagation in 2D TTI Anisotropic Media M. Grini* (Géosciences Azur - CNRS) A. Ribodetti (Géosciences Azur - IRD) J. Virieux (Géosciences Azur - UNSA) & S. Operto (Geosciences Azur - CNRS) SUMMARY We present a 2D finite-difference frequency-domain method for modeling acoustic wave propagation in TTI media. The numerical method relies on a parsimonious staggered-grid method implemented in the frequency domain. Discretization of the differential operators is performed along 45° rotated directions. We applied this discretization strategy to the anisotropic acoustic wave equation for TTI media derived by Zhou (2006). The finite-difference stencil ..
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
SMART: dissipative absorbing layer technique for general elastodynamics equations. Application as S-waves filter in acoustic TI media
No full textInternational audienceSeismic imaging methods such as FullWaveform Inversion (FWI Virieux and Operto [38], M´etivier et al. [30, 28]) or Reverse Time Migration (RTM Baysal et al. [6]) require accurate modeling engines for the propagation of seismic waves in infinite or semi-infinite media. To this end, the use of efficient absorbing boundary conditions is mandatory. Moreover, one should be sure that the modeling engine will provide always an answer at each iteration of the inversion and of the migration. The stability is, therefore, a very important property of absorbing conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Parental stress in pediatric epilepsy after therapy withdrawal
No full textObjective: The objective of the study was to explore stress levels in the parents of children with idiopathic epilepsy at different time points of the disease, specifically, at the time of diagnosis, during follow-up, and 1 and 2 years after discontinuation of antiepileptic drugs.Methods: Our study included 50 patients between 5 and 14 years of age, who were diagnosed with childhood absence epilepsy or idiopathic focal epilepsy with Rolandic paroxysms. Parents of the participants independently completed the Parenting Stress Index-Short Form at the time of initial diagnosis, and when the children started antiepileptic drugs (Time 0), and at 1 year (Time 1) and 2 years (lime 2) after discontinuation of therapy.Results: At Time 0, parental stress levels were increased, both in mothers and fathers, with average scores in the "clinical range" of the parental distress (PD), dysfunctional parent-child interaction (P-CDI), and total stress (TS) scales. At Time 1, the scores on these scales remained high. At Time 2, a mild reduction in the stress scores was observed in both parents, despite values remaining in the "clinical range" for all the scales.Conclusions: Results suggested that parents of children with epilepsy were not reassured about the child's condition, even after clinical improvement. Parental stress levels remained higher than expected, even 2 years after the discontinuation of therapy and freedom from seizures. This was probably due to concerns with the reappearance of new seizures or a more severe type of epilepsy with the discontinuation of drug(s), and feelings of inadequacy with their parental role(s). (C) 2019 Elsevier Inc. All rights reserved
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