Conditions are determined for which optical interconnects can transmit information at a higher data rate and consume lc3s power than the equivalent electrical interconnections. The analysis is performed for free-space optical intrachip communication links. Effects of scaling circuit dimensions, presence of signal fan-out, and the use of light modulators as optical signal transmitters are also discussed.

We investigate an incremental recording technique for multiplexed hologram storage in photorefractive crystals, in which each hologram is recorded with multiple short exposures. The performance is theoretically compared with that of scheduled (single exposure per hologram) recording. Our analysis shows that this technique systematically controls the signal uniformity and can also decrease the total recording time. We present an experimental demonstration with LiNbO(3) using a binary orthogonal phase-code addressing technique.

A confocal Fabry-Perot processor, with coherent image amplification provided by a photorefractive BaTiO(3) crystal in the feedback path, is analyzed and implemented to perform the iterative algorithm based on the relation B(-1) = (I - A)(-1) = (infinity)Sigma(k=0) A(k), where B is the matrix to be inverted and I is the identity matrix. Both A and B are large size matrices. When the feedback loop contains a coherent matrix-vector multiplier (AX) and the input vector is sequentially scanned from one element to another, the columns of B(-1) can be sequentially generated at the output. The photorefractive BaTiO(3) amplifier provides loss compensation and coherence restoration of the feedback signal, thereby increasing the effective number of iterations in the algorithm. Thus it becomes possible to use this technique to implement slowly (as well as rapidly) converging algorithms. Experimental verification of the matrix inversion algorithm is presented, along with an analysis of possible real-time operations.

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The biochemical composition of the chaetognath Parasagitta elegans from the hyperbenthic zone of Conception Bay, Newfoundland, was determined from April 1997 to June 1998. Lipid and carbohydrate levels (% dry weight) were relatively high in the spring and summer and low in the fall and winter. Conversely, the relative protein level was low in the spring and summer and high in the fall and winter. Carbon level was generally high in the spring and summer of 1997 but low from fall to the following spring, whereas inorganic ash level showed the opposite seasonal trend. Lipid and carbohydrate levels and the C/N ratio were positively correlated with chaetognath maturity stage, while protein levels were negatively correlated with chaetognath maturity. These results indicate that P. elegans were lipid-and carbohydrate-rich while maturing during spring and summer, and that immature individuals were protein-rich while achieving somatic growth during fall and winter. This increase in the levels of lipid and carbohydrate occurred when mature copepods increased in the spring and summer rather than when total abundance of copepods increased in the fall. Thus, it appears that food quality rather than quantity affects the biochemical levels and reproductive cycle of P. elegans. In addition, the maximum abundance of adult copepods occurred 3 wk after the peak of the spring bloom, and the maximum relative abundance of mature P. elegans occurred 3 wk later. This suggests that there is tight coupling of energy transfer from primary producers to carnivorous hyperbenthic chaetognaths following the spring phytoplankton bloom in Newfoundland coastal waters. Therefore, seasonal variation in the biochemical composition of P. elegans in the hyperbenthic zone of Conception Bay is closely related to its reproductive cycle and to food quality. Furthermore, it is clear that the chaetognath reproductive cycle is synchronized with the massive energy input from the annual spring phytoplankton bloom.

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The pattern-recognition algorithms based on eigenvector analysis (group 2) are theoretically and experimentally compared. Group 2 consists of Foley-Sammon (F-S) transform, Hotelling trace criterion (HTC), Fukunaga-Koontz (F-K) transform, linear discriminant function (LDF), and generalized matched filter (GMF) algorithms. It is shown that all eigenvector-based algorithms can be represented in a generalized eigenvector form. However, the calculations of the discriminant vectors are different for different algorithms. Summaries of methods of calculating the discriminant functions for the F-S, HTC, and F-K transforms are provided. Especially for the more practical, underdetermined case, where the number of training images is less than the number of pixels in each image, the calculations usually require the inversion of a large, singular pixel correlation (or covariance) matrix. We suggest solving this problem by finding its pseudoinverse, which requires inverting only the smaller, nonsingular imagecorrection (or covariance) matrix plus multiplying several nonsingular matrices. We also compare theoretically the classification performance with discriminant functions of the F-S, HTC, and F-K with the LDF and GMF algorithms and the linear-mapping-based algorithms with the eigenvector-based algorithms. Experimentally, we compare the eigenvector-based algorithms, using two sets of image data bases with each image consisting of 64 x 64 pixels.