Biomedical subjects

J Lazzaro

Publications and source records attributed to J Lazzaro.

3 recordsLinked to original sources

PubMed2001

Atropisomeric quinazolin-4-one derivatives are potent noncompetitive alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonists.

Piriqualone (1) was found to be an antagonist of AMPA receptors. Structure activity optimization was conducted on each of the three rings in 1 to afford a series of potent and selective antagonists. The sterically crowded environment surrounding the N-3 aryl group provided sufficient thermal stability for atropisomers to be isolated. Separation of these atropisomers resulted in the identification of (+)-38 (CP-465,022), a compound that binds to the AMPA receptor with high affinity (IC50 = 36 nM) and displays potent anticonvulsant activity.

Animals↗

PubMed1999

JPEG quality transcoding using neural networks trained with a perceptual error measure.

A JPEG Quality Transcoder (JQT) converts a JPEG image file that was encoded with low image quality to a larger JPEG image file with reduced visual artifacts, without access to the original uncompressed image. In this article, we describe technology for JQT design that takes a pattern recognition approach to the problem, using a database of images to train statistical models of the artifacts introduced through JPEG compression. In the training procedure for these models, we use a model of human visual perception as an error measure. Our current prototype system removes 32.2% of the artifacts introduced by moderate compression, as measured on an independent test database of linearly coded images using a perceptual error metric. This improvement results in an average PSNR reduction of 0.634 dB.

Algorithms↗

PubMed1989

Silicon modeling of pitch perception.

We have designed and tested an integrated circuit that models human pitch perception. The chip receives as input a time-varying voltage corresponding to sound pressure at the ear and produces as output a map of perceived pitch. The chip is a physiological model; subcircuits on the chip correspond to known and proposed structures in the auditory system. Chip output approximates human performance in response to a variety of classical pitch-perception stimuli. The 125,000-transistor chip computes all outputs in real time by using analog continuous-time processing.

Computer Simulation↗