Spiral waves are frequently observed in a large variety of excitable media, such as the Belousov– Zhabotinsky (BZ) reactions [Winfree, 1972; Ouyang & Flesselles, 1996], the catalytic surface processes [Jakubith et al., 1990], the cardiac tissue [Davidenko et al., 1992; Qu et al., 2000] and neural networks [Sbitnev, 1998]. One common feature of spiral waves is that with the variation of the envi...

BOLD fMRI is hampered by dropout of signal in the orbitofrontal and parietal brain regions due to magnetic field gradients near air-tissue interfaces. This work reports the use of spiral-in trajectories that begin at the edge of k-space and end at the origin, and spiral in/out trajectories in which a spiral-in readout is followed by a conventional spiral-out trajectory. The spiral-in trajectory...

We derive regions for T-cubic and arc/T-cubic spirals to two-point Hermite interpolation in terms of unit tangent vectors with help of Mathematica. The use of spirals gives the designer an excellent and speedy control over the shape of curve that is produced because there are no internal curvature maxima, curvature minima, inflection points, loops and cusps in a spiral segment.

We employ low-energy electron microscopy to study the kinetics of thermal etching, or sublimation, of Cr(001) at approximately 1100 K. Atomic layers are removed from the surface by spontaneous nucleation and growth of two-dimensional vacancy islands, by rotation of spiral steps, and by island decay. The growth rates of vacancy islands and the rotation frequencies of double spirals are measured ...

Chirality, tailored by external morphology and internal composition, has been realized by controlled curved-lattice epitaxial growth of In(x)Al(1-x)N nanospirals. The curved morphology of the spiral segments is a result of a lateral compositional gradient while maintaining a preferred crystallographic growth direction, implying a lateral gradient in optical properties. Individual nanospirals sh...

Hierarchical ZnO nanostructures with a large yield were fabricated by a simple thermal evaporation method. For the first time, novel ZnO flowers were observed blooming at certain sites of a variety of spines, identified as Zn-terminated polar (0001) planes or tips. The spines for as-synthesized hierarchical structures can be nanowires, nanobelts, nanodendrites, nanobrushes, etc. This growth phe...

Using C2H2, 112 and As gases at 550'C, carbon nanotubes were fabricated on the surfaces of twosubstrates coated by nano thin layers of metal catalysts by DC magnetron sputtering. AYStamless steel andFe/CteAl, by thermal chemical vapor deposition (TCVD) The surface properties of the substrates wereparticularly investigated, and the effect of treatment of the substrates on the CNT's growth is cri...