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Attentional Blink: An Antecedent to Binge Eating BehaviorDenke, Gregory 18 December 2014 (has links)
This study examined how attentional sub-processes contribute to binge-eating. Dense-array EEG and a version of the canonical attentional blink task were used to ascertain the neural correlates underlying the attentional sub-processes that comprise the Posner model of attention (alerting, orienting, and executive control) and how attentional activation differs for binge-eaters vs. non-binge eaters. Furthermore, we examined a number of the event-related potentials (ERP), including P2 activation, which has been linked with orientating of attention, and N2 activation which has been linked with attentional conflict. We found decreased P2 activation for binge-eaters, in the negative condition, for incorrect target 2 (T2) detection trials. We also found more N2 activation for binge-eaters than non-binge eaters, in negative trials when T2 was not detected. This pattern of results suggest that binge-eaters showed deficiencies in allocating attention to stimuli that followed negative images; this attention deficiency may be a key factor for binge-eating behavior.
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Localisation d'évènements sismiques en proche surface sur la faille de San Jacinto à l'aide d'un réseau dense de capteurs / Localization of subsurface seismic events on the San Jacinto faultusing a dense array of sensorsGradon, Chloé 15 January 2019 (has links)
Cette thèse traite de la détection et de la localisation de sources autour de la faille de San Jacinto. Son but était de détecter des sources dans la croute superficielle, sur des profondeurs de l'ordre de quelques kilomètres. Ces sources ont une faible énergie et émettent principalement dans les hautes fréquences. Les sources à la surface autour et sur le réseau possèdent les mêmes caractéristiques et sont aussi étudiées afin de pouvoir les séparer des évènements en profondeur.Une méthode basée sur le traitement d'antenne, le Match Field Processing (MFP), est utilisée pour détecter et localiser de faibles évènements à faible profondeur et à la surface. Le MFP est appliqué a des données mesurées grâce a un réseau dense de capteurs une composante déployés sur une zone de 600mx600m sur la faille de San Jacinto. La méthode a d'abord été testée sur un ensemble d'évènements à la surface et en profondeur. Nous appliquons ensuite la technique sur 26 jours de données, afin de déterminer si des évènements sont présents en proche surface. Pour cela, seules la position en surface de la source et la vitesse apparente des ondes émises sont utilisés comme paramètres d'inversion. L'utilisation de ces trois paramètres permet de réaliser une première étude à moindre coût de calcul. Cependant cette première inversion ne permet pas de conclure sur la présence de sources en proche surface. L'information sur la position de la source en profondeur est nécessaire. Les résultats de localisations qui incluent la profondeur comme paramètre étant peu concluants lorsque le modèle classique de vitesse homogène est utilisé, nous étudions ensuite différentes stratégies pour améliorer la résolution en profondeur sans augmenter le coût de calcul. / The focus of this thesis is the detection and localization of weak sources on the San Jacinto Fault Zone. The primary targets of interest are sources in the shallow crust, with depth down to a few kilometers. For sources at these depths high frequency content and low energy are expected. Surface sources present on and around the array site are also studied in order to discriminate them from weak seismic sources at depth.We rely on a methodology based on array processing to detect and localize shallow and weak seismic events in the fault zone complex environment. We use Match field Processing on data recorded from a dense array of 1108 vertical component geophones in a 600m x 600m area on the Clark branch of the San Jacinto Fault. We first test the method on a set of chosen events at depth and at the surface. Source epicentral positions and associated apparent velocities are then inverted for surface and seismic sources for 26 days, with the intention of determining if shallow sources are present. Inverting only for these three parameters is less expensive in terms of computational cost and is suitable for a first approach. However, this first inversion leaves us unable to conclude on the presence of shallow sources. As the resolution at depth is insufficient when all three source coordinates are inverted with a classical homogeneous velocity model, we finally investigate strategies to improve resolution at depth without increasing computational cost.
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Geologic and Structural Characterization of Shallow Seismic Properties Along The San Jacinto Fault at Sage Brush Flat, Southern CaliforniaJanuary 2018 (has links)
abstract: The study of fault zones is a critical component to understanding earthquake mechanics and seismic hazard evaluations. Models or simulations of potential earthquakes, based on fault zone properties, are a first step in mitigating the hazard. Theoretical models of earthquake ruptures along a bi-material interface result in asymmetrical damage and preferred rupture propagation direction. Results include greater damage intensity within stiffer material and preferred slip in the direction of the more compliant side of the fault. Data from a dense seismic array along the Clark strand of the SJFZ at Sage Brush Flat (SGB) near Anza, CA, allows for analysis and characterization of shallow (<1km depth) seismic structure and fault zone properties. Results indicate potential asymmetric rock damage at SGB, similar to findings elsewhere along the SJFZ suggesting an NW preferred rupture propagation.
In this study, analysis of high resolution topography suggests asymmetric morphology of the SGB basin slopes are partially attributed to structural growth and fault zone damage. Spatial distributions of rock damage, from site mapping and fault perpendicular transects within SGB and Alkali Wash, are seemingly asymmetric with pulverization dominantly between fault strands or in the NE fault block. Remapping of the SJFZ through Alkali Wash indicates the fault is not isolated to a single strand along the main geologic boundary as previously mapped. Displacement measurements within SGB are analogous to those from the most recent large earthquake on the Clark fault. Geologic models from both a 3D shear wave velocity model (a product from the dense seismic array analysis) and lithologic and structural mapping from this study indicate surface observations and shallow seismic data compare well. A synthetic three-dimensional fault zone model illustrates the complexity of the structure at SGB for comparison with dense array seismic wave products. Results of this study generally agree with findings from seismic wave interpretations suggesting damage asymmetry is controlled by a NW preferred rupture propagation. / Dissertation/Thesis / Geologic Map of Sage Brush Flat / 3D fault zone model of the SJFZ at Sage Brush Flat / Masters Thesis Geological Sciences 2018
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