Crystal and molecular structure of the smectogenic compound di-n-propyl-p-terphenyl-4,4″-carboxylate

An X-ray crystallographic study of di-n-propyl-p-terphenyl-4,4-carboxylate (DPTC) showed that the crystals belong to the triclinic system with space groupP¯1,a=22.191(14),b=5.960(1),c=10.951(4) Å, =129.651(16), =102.560(51), and =83.103(39) ° with two molecules per unit cell. The crystal structure was solved by Patterson synthesis, Fourier, and difference Fourier calculations. It was refined by block-diagonal and full-matrix least-squares methods to a finalR factor of 0.17. The molecules form a herringbone type of packing in tilted layers. Each of the two molecules is nonplanar in itself and shows highly anisotropic behavior of the end groups.     

Positive magnetoresistance due to conduction-band splitting in EuSe and EuTe

A positive magnetoresistance observed in _n-type EuSe and EuTe samples is explained by the effect of spin splitting of the conduction band on nonmagnetic scattering.     

Free space radiation mode analysis of rectangular dielectric waveguides

The free space radiation mode (FSRM) method is used to provide a new closed-form transcendental equation for the scalar mode propagation constant of a uniformly buried rectangular dielectric waveguide. Results are readily and rapidly obtained and are shown to be very accurate over the range of practical interest.     

A model for the computation and encoding of azimuthal information by the lateral superior olive

A structural model is proposed for the processing of interaural intensity differences by the lateral superior olive. One fundamental assumption is that the incoming excitatory projections from the ipsilateral anteroventral cochlear nucleus innervate columns of LSO neurons serially according to threshold. A second fundamental assumption is that the inhibitory innervation from the ipsilateral medial nucleus of the trapezoid body is also serially arranged according to threshold but in the opposite direction along the LSO column. Using neurophysiological and neuroanatomical data for neuronal response curves, connectional patterns, and cell and synapse numbers, the model was formulated quantitatively and implemented for machine computation. Azimuthal location is encoded by the position along the LSO column where LSO cell firing first goes to zero. Accuracy of coding was tested for three different connectional schemes, for variations in neuronal parameters, and for cell and synapse death. Encoding is shown to be independent of absolute sound level and to vary linearly with interaural intensity difference.