Using the technique developed by Newman and Okal [J. Geophys. Res. 103 (1998) 26885], a dataset of digital records from 84 earthquakes is analyzed to investigate their source slowness in the quest for a possible regional signal in three subduction zones which experienced recent tsunami earthquakes (Nicaragua, 1992; Java, 1994; Peru, 1996). The dataset is augmented by analog seismograms from his...

Tomography refers to the technique of reconstructing a field from line or surface integrals of it. In medical X-ray tomography, for example, the tissue density field is deduced from measurements of X-ray attenuation through the patient. In this case the data are regularly sampled line integrals, so they are discrete values of a Radon transform. In seismology, the determination of slowness (inve...

[1] Seismic phases diffracted around Earth’s core contain information about lowermost mantle wave speeds. By measuring the slowness of incident diffracted energy from array recordings, seismic velocity along the diffracted path can be estimated. Here we apply this principle to diffraction of the major arc seismic phase PKKPab recorded at the Canadian Yellowknife array to estimate P wave velocit...

Instantaneous frequency-slowness method (IFS) is based on complex wave form analysis. It delivers the same measures as complex wave form method e.g. slowness and standard deviation, goodness of the data and receiver responses across the neighbouring pairs. Additionally, IFS method computes instantaneous frequency and slowness wave forms as seen between adjacent receivers. Classic semblance meth...

A new 2-D traveltime tomography algorithm has been developed for use with long offset seismic streamer data. The forward problem is solved using initial value ray tracing in Delaunay triangulated grids. The traveltimes are calculated analytically. The linearised joint interface and velocity inversion is regularised via a geostatistical smoothing regularisation based on the formulation of a data...

Loss of the ability to move is the most characteristic and fundamental motor deficit in Parkinson’s disease. Parkinsonian patients exhibit akinesia (inability to initiate movement), hypokinesia (reduced movement), and bradykinesia (slowness of the movement itself). (All these phenomena will be subsumed under the title akinesia.) Rigid muscles may contribute to akinesia, but they are not the cau...

S U M M A R Y We propose a level-set adjoint-state method for crosswell traveltime tomography using both first-arrival transmission and reflection traveltime data. Since our entire formulation is based on solving eikonal and advection equations on finite-difference meshes, our traveltime tomography strategy is carried out without computing rays explicitly. We incorporate reflection traveltime d...

The distributed hash table, or DHT, is a distributed system that provides a traditional hash table’s simple put/get interface using a peer-to-peer overlay network. To echo the prevailing hype, DHTs deliver incremental scalability in the number of nodes, extremely high availability of data, low latency, and high throughput. Over the past 16 months, we have run a public DHT service called OpenDHT...

In the Kappa effect, two visual stimuli are given, and their spatial distance affects their perceived temporal interval. The classical model assumes constant speed while a competing Bayesian model assumes a slow speed prior. The two models are based on different assumptions about the statistical structure of the environment. Here we introduce a new visual experiment to distinguish between these...

A growing body of evidence suggests that action videogames could enhance a variety of cognitive skills and more specifically attention skills. The aim of this study was to develop a novel adaptive videogame to support the rehabilitation of the most common consequences of traumatic brain injury (TBI), that is the impairment of attention and executive functions. TBI patients can be affected by ps...