Examples of test electromagnetic waves on a Friedmann–Lemâıtre– Robertson–Walker (FLRW) background are constructed from explicit perturbations of the FLRW space–times describing gravitational waves propagating in the isotropic universes. A possible physical mechanism for the production of the test electromagnetic waves is shown to be the coupling of the gravitational waves with a test magnetic ...

We model a backward mirrorless optical parametric oscillator in a fragmented GaN waveguide consisting of a sequence of submicronic periodically poled elements separated by uniformly polarized connection sections representing stitching errors. We find that the generated coherent phase of the backscattered wave locks the phases of the forward propagating waves in such a way that the dynamics is n...

Trigger waves are a recurring biological phenomenon involved in transmitting information quickly and reliably over large distances. Well-characterized examples include action potentials propagating along the axon of a neuron, calcium waves in various tissues, and mitotic waves in Xenopus eggs. Here we use the FitzHugh-Nagumo model, a simple model inspired by the action potential that is widely ...

Congenital deafness affects developmental processes in the auditory cortex. In this study, local field potentials (LFPs) were mapped at the cortical surface with microelectrodes in response to cochlear implant stimulation. LFPs were compared between hearing controls and congenitally deaf cats (CDCs). Pulsatile electrical stimulation initially evoked cortical activity in the rostral parts of the...

We show that intensity-dependent depolarization of single pulses may be due to the nonlinear decay of the "upper" ordinary (O) mode into an unpolarized extraordinary mode and a backward-propagating wave. The decay occurs in the innermost parts of the pulsar magnetosphere for obliquely propagating O waves.

1 ABSTRACT 5 We introduce the modulation of the ITCZ equations (M-ITCZ) which describe 6 the multi-scale dynamics of the ITCZ on one day to one month time scales in 7 which mesoscale convectively coupled Rossby waves in the ITCZ are modulated 8 by a large scale gravity wave which is also generated by convection. Westward 9 propagating disturbances are observed to cause ITCZ breakup over the cou...

The aim of this study was to examine the relationship between colonic pressure waves and movement of content. In 11 healthy subjects, pressures were recorded at 10-cm intervals from cecum to rectum for 32 h. In six subjects, transit was simultaneously measured for 8 h after direct cecal instillation of 1.5 mCi of (99m)Tc sulfur colloid. Thirty-two percent of isotope movements were related to no...

3391 Periodic structures with linear defects have been traditionally analyzed with the ω(ï¿¿ k) methods with the supercell approximation. The presence of the linear defect introduces guided modes at frequencies in the band gap of the complete structure. This methodology only considers the propagating properties of the periodic system. In this work we report both theoretical predictions and expe...

Propagating waves of activity have been recorded in many species, in various brain states, brain areas, and under various stimulation conditions. Here, we review the experimental literature on propagating activity in thalamus and neocortex across various levels of anesthesia and stimulation conditions. We also review computational models of propagating waves in networks of thalamic cells, corti...

By employing a local two-fluid theory, we investigate an obliquely propagating electromagnetic instability in the lower hybrid frequency range driven by cross-field current or relative drifts between electrons and ions. The theory self-consistently takes into account local cross-field current and accompanying pressure gradients. It is found that the instability is caused by reactive coupling be...