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To estimate changes in regional cerebral blood flow (rCBF) without arterial sampling in the study of functional-anatomical correlations in the human brain, using (15)O-labeled water and PET, a standard arterial input function was generated from the input function in 10 normal volunteers with dose calibration and peak time normalization. The speed and volume of injection were precisely controlled with a mechanical injector. After global normalization of each tissue activity image, the standard arterial input function was applied to obtain estimated CBF images. Relative changes in estimated rCBF to whole brain mean CBF(DeltaFest) and those in regional tissue activity (DeltaC) were compared with true relative rCBF changes (DeltaF) in 40 pairs of images obtained from 6 normal volunteers. DeltaFest correlated well with DeltaF, whereas DeltaC consistently underestimated DeltaF. This noninvasive method simplifies the activation studies and provides the accurate estimation of relative flow changes.

The ternary oxide solution of lead zirconate titanate (PZT) with a complex perovskite oxide Pb(Zn(1/3)Nb(2/3))O(3 ), (PZN), a composition that is near that of PbZrO(3), was prepared, and its phase transition behavior was investigated. An extension of the ferroelectric phase by the addition of PZN and a change of the transition between two ferroelectric phases from a first-order to a second-order nature are described.

The authors present a novel nonlinear regulator design method that integrates linear optimal control techniques and nonlinear neural network learning methods. Multilayered neural networks are used to add nonlinear effects to the linear optimal regulator (LOR). The regulator can compensate for nonlinear system uncertainties that are not considered in the LOR design and can tolerate a wider range of uncertainties than the LOR alone. The salient feature of the regulator is that the control performance is much improved by using a priori knowledge of the plant dynamics as the system equation and the corresponding LOR. Computer simulations are performed to show the applicability and the limitations of the regulator.

Acoustooptic Bragg deflectors (ABDs) with high diffraction efficiencies were fabricated using ZnO thin films deposited on sapphire, glass, and Si substrates by an RF magnetron sputtering system. Optical waveguide losses of the ZnO films were about 0.5 dBcm(-1). Diffraction efficiencies of 95 and 98% for the TE(0) mode beam (at 632.8 nm) were accomplished by acoustic powers of 90 mW in a ZnO film on glass and 80 mW in a ZnO film on Si, respectively. The diffraction efficiencies of the ABD using a ZnO film on sapphire with interdigital transducers of different Q values and with the surface-acoustic-wave propagating along and perpendicular to the c -axis of the ZnO film were also determined.