Extreme acoustic anisotropy in crystals visualized by diffraction tensor

Extreme anisotropy of wave propagation in two-dimensional photonic crystals.

We demonstrate that electromagnetic waves propagating in square and hexagonal photonic crystals can have fundamentally different anisotropy properties. The wave frequency and group velocity can be functions of the propagation direction even for vanishingly small wave numbers (near the gamma-point). This anisotropy, present in square but absent in hexagonal lattices, can be so extreme that the g...

Influence of Strong Acoustic Anisotropy on Reflection of Bulk Acoustic Waves in Crystals

Propagation and reflection of plane elastic waves in the acousto-optic crystals tellurium dioxide and calomel as well as in the ferroelectric material barium titanate is examined in the paper. The reflection of the waves from a free and flat boundary separating the crystal and the vacuum is investigated in the (001) planes of TeO2, Hg2Cl2, and BaTiO3 in the case of glancing acoustic incidence o...

Shape anisotropy: tensor distance to anisotropy measure

Fractional anisotropy (FA), defined as the distance of a diffusion tensor from its closest isotropic tensor, has been extensively studied as quantitative anisotropy measure for diffusion tensor magnetic resonance images (DT-MRI). It has been used to reveal the white matter profile of brain images, as guiding feature for seeding and stopping in fiber tractography and for the diagnosis and assess...

Switchable Diffraction Gratings Based on Inversion of the Dielectric Anisotropy in Nematic Liquid Crystals

Asymmetry of subinsular anisotropy by in vivo diffusion tensor imaging.

The cortical regions specialized in speech-language exhibit a left-right asymmetry, e.g., a larger cortical size in the left auditory cortex and Wernicke's area. The possibility of developmental asymmetry in axonal fibers interconnecting speech-language cortical areas can be investigated by in vivo diffusion tensor imaging. Fifteen right-handed native English speakers showed a markedly signific...