David C. P. Chen

Programmable-weight building blocks for analog VLSI neural network processors

Although the neural network paradigms have the intrinsic potential for parallel operations, a traditional computer cannot fully exploit it because of the serial hardware configuration. By using the analog circuit design approach, a large amount of parallel functional units can be realized in a small silicon area. In addition, appropriate accuracy requirements for neural operation can be satisfied. Components for a general-purpose neural chip have been designed and fabricated. Dynamically adjusted weight value storage provides programmable capability. Possible reconfigurable schemes for a general-purpose neural chip are also presented. Test of the prototype neural chip has been successfully conducted and an expected result has been achieved.

A compact neural-network-based CDMA receiver

A compact neural-network receiver for code-division multiple-access (CDMA) communication is presented. In the CDMA scheme, the near-far problem is a major impediment for the performance of a conventional detector (CD). By using a compact neural network with hardware annealing function and gradient-descent optimization technique, an optimal multiuser receiver can be implemented. The algorithm and simulation results of the compact neural-network-based CDMA receiver are described.

A compact neural network based CDMA receiver for multimedia wireless communication

A compact neural network receiver to process code division multiple access (CDMA) communication is presented. In CDMA system, near-far problem is a major impediment for the performance of a conventional detector. By using a compact neural network with hardware annealing function and combinatorial optimization technique, an optimal multiuser detector can be implemented. The algorithm and architecture of the compact neural network based CDMA receiver are described.

Missed torsion of an undescended testicle detected by testicular scintigraphy.

The authors present a case in which a Tc-99m pertech-netate scan revealed a missed torsion of an undescended testis in a 7-month-old boy who presented with persistent pain in the right inguinal region for 3 days.

Gallium-67 uptake in cutaneous lesions of mycosis fungoides.

The literature on gallium imaging in mycosis fungoides is limited and conflicting. A case of mycosis fungoides with increased uptake of Ga-67 in clinically noninfected skin lesions is reported. The literature regarding mycosis fungoides and gallium imaging is reviewed

A CDMA communication detector with robust near-far resistance using paralleled array processors

The code division multiple access (CDMA) scheme has become very popular due to high efficiency for spectrum usage and robust jamming resistance. However, the inherent near-far problem is an impediment. Though deliberate power control algorithms can partially handle this problem, the cost is high. Under the assumption of synchronous symbols and white Gaussian noise, a neural-network-based detector with robust near-far resistance is presented. By proper mapping and applying a hardware annealing technique, compact realization of high precision detectors is possible.

Ga-67 uptake in cutaneous B-cell lymphoma.

Cutaneous B cell lymphoma is not commonly seen and occurs in only 8.2% of non-Hodgkins lymphoma. Although Ga-67 uptake by cutaneous T cell lymphoma has been reported, the literature on Ga imaging in cutaneous, B cell lymphoma is limited. The authors report the gallium scan and clinical findings on 2 cases of cutaneous B cell lymphoma.

Non Hodgkins lymphoma of the breast, unusual presentation: detection by 67Ga scintigraphy.

Lymphomatous involvement of the breast is an uncommon cause of breast masses. A case is presented of a patient with bilateral breast involvement revealed by intense 67Ga uptake. Other foci of involvement were also detected scintigraphically, and confirmed by other imaging modalities. Multiagent chemotherapy resulted in significant clinical and scintigraphic regression of tumor, demonstrating the potential utility of 67Ga imaging in the followup of these patients.

Dermatofibrosarcoma protuberans of the toe : findings on multiple imaging modalities

Dermatofibrosarcoma protuberans occurs early in life, is an unusual soft tissue tumor, and is uncommonly seen distal to knees. The authors present a rare case of dermatofibrosarcoma protuberans of the toe with different imaging modalities.

Analysis of the quantitative structure activity relationship of technetium-99m-labeled diaminedithiol (DADT) and propyleneamineoxime (PAO) brain blood flow analogues

In the search for new brain imaging agents for the use with single photon emission computed tomography (SPECT), quantitative structure activity relationship (QSAR) analysis of the correlations between initial brain uptake and physicochemical parameters like lipophilicity, log P, molecular weight, log MW and log U/D (undissociated/dissociated), of the 99mTc-DADT (diaminedithiol) complexes and 99mTc-PAO (propyleneamineoxime) complexes have been analyzed. High correlations are found for both the 99mTc-DADT complexes (r = 0.94) and for the 99mTc-PAO complexes (r = 0.83) which are significant at 99.9 and 99.5 percentile level, respectively. These results will help the further design of better ligands for 99mTc in brain imaging.