44 research outputs found
Serological epitope profile of anti-Ro52âpositive patients with systemic autoimmune rheumatic diseases
Moving sounds enhance the visually-induced self-motion illusion (circular vection) in virtual reality
Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions
Matched Field Processing of Three-Component Seismic Array Data Applied to Rayleigh and Love Microseisms
We extend threeâcomponent plane wave beamforming to a more general form and devise a framework, which incorporates velocity heterogeneities of the seismic propagation medium and allows us to estimate accurately sources that do not follow the simple plane wave assumption. This is achieved by utilizing fast marching to track seismic wave fronts for given surface wave phase velocity maps. The resulting matched field processing approach is used to study the surface wave locations of Rayleigh and Love waves at 8 and 16 s based on data from four seismic arrays in the western United States. By accurately accounting for the path propagation effects, we are able to map microseism surface wave source locations more accurately than conventional plane wave beamforming. In the primary microseisms frequency range, Love waves are dominant over Rayleigh waves and display a directional radiation pattern. In the secondary microseisms range, we find the general source regions for both wave types to be similar, but on smaller scales differences are observed. Love waves are found to originate from a larger area than Rayleigh waves and their energy is equal or slightly weaker than Rayleigh waves. The energy ratios are additionally found to be source location dependent. Potential excitation mechanisms are discussed which favor scattering from RayleighâtoâLove waves
Top-down and multi-modal influences on self-motion perception in virtual reality
INTRODUCTION: Much of the work on self-motion perception and simulation has investigated the contribution of physical stimulus properties (so-called âbottom-up â factors). This paper provides an overview of recent experiments demonstrating that illusory self-motion perception can also benefit from âtop-down â mechanisms, e.g. expectations, the interpretation and meaning associated with the stimulus, and the resulting spatial presence in the simulated envi-ronment. METHODS: Several VR setups were used as a means to independently control different sensory modali
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Shallow Crustal Shear Velocity and Vp/Vs Across Southern California: Joint Inversion of Short-Period Rayleigh Wave Ellipticity, Phase Velocity, and Teleseismic Receiver Functions
Near-surface seismic velocity structure plays a critical role in ground motion amplification during large earthquakes. In particular, the local Vp/Vs ratio strongly influences the amplitude of Rayleigh waves. Previous studies have separately imaged 3D seismic velocity and Vp/Vs ratio at seismogenic depth, but lack regional coverage and/or fail to constrain the shallowest structure. Here, we combine three datasets with complementary sensitivity in a Bayesian joint inversion for shallow crustal shear velocity and near-surface Vp/Vs ratio across Southern California. Receiver functionsâincluding with an apparent delayed initial peak in sedimentary basins, and long considered a nuisance in receiver function imaging studiesâhighly correlate with short-period Rayleigh wave ellipticity measurements and require the inclusion of a Vp/Vs parameter. The updated model includes near-surface low shear velocity more in line with geotechnical layer estimates, and generally lower than expected Vp/Vs outside the basins suggesting widespread shallow fracturing and/or groundwater undersaturation