We exhibit all spatially isotropic homogeneous Galilean spacetimes of dimension $(n+1) \geq 4$, including the novel torsional ones, as null reductions pp-wave spacetimes. also show that pp-waves are sourced by pure radiation fields and analyse their global properties.

We present a novel Material Point Method (MPM) discretization of surface tension forces that arise from spatially varying energies. These variations typically energy dependence on temperature and/or concentration. Furthermore, since the is an interfacial property depending types materials either side interface, spatial variation required for modeling contact angle at triple junction between liq...

A spatially extended version of the game of prisoner's dilemma, originally proposed by Nowak and May, is modified to include stochastic updating and found to exhibit scale-invariant behavior. Two critical regimes with different scaling behaviors are found; the corresponding exponents have been determined numerically. Spatially, the critical states are characterized by the existence of delicatel...

Patterns of activity over real neural structures are known to exhibit timedependent behavior. It would seem that the brain may be capable of utilizing temporal behavior of activity in neural networks as a way of performing functions which cannot otherwise be easily implemented. These might include the origination of sequential behavior and the recognition of time-dependent stimuli. A model is p...

The striatum is the main input nucleus of the basal ganglia. Characterizing striatal activity dynamics is crucial to understanding mechanisms underlying action selection, initiation, and execution. Here, we studied the effects of spatial network connectivity on the spatiotemporal structure of striatal activity. We show that a striatal network with nonmonotonically changing distance-dependent co...

Local and superficial near-infrared (NIR) optical-property characterization of turbid biological tissues can be achieved by measurement of spatially resolved diffuse reflectance at small source-detector separations (<1.4 mm). However, in these conditions the inverse problem, i.e., calculation of localized absorption and the reduced scattering coefficients, is necessarily sensitive to the scatte...

Spatially explicit individual-based models are widely used in ecology but they are often difficult to treat analytically. Despite their intractability they often exhibit clear temporal and spatial patterning. We demonstrate how a spatially explicit individual-based model of scramble competition with local dispersal can be approximated by a stochastic coupled map lattice. The approximation disen...