Disjoint path properties of the data manipulator network family

A critical component of any parallel processing system is the interconnection network that provides communications among the system's processors and memories. The data manipulator (gamma) network family is an important class of multistage interconnection networks that is being studied by various researchers. One interesting property of the data manipulator network family is the existence of multiple paths through the network for most source/ destination pairs. The condition that must be present to have disjoint paths through the network for a given source/ destination pair is shown, where disjoint paths are multiple paths with no links in common. It is derived that the maximum number of disjoint paths for any source/destination pair is two and a method for finding the routing tags that specify these paths is given. For source/destination pairs that have disjoint paths, a single fault cannot prevent communication between that source/ destination pair. The effect of a fault in a given stage of the network on the number of source/destination pairs that can be connected is also discussed. All results are proven mathematically.     

Ultrasonic Duplex Echo-Doppler Scanner

Ultrasonic B-mode displays are produced by a new diagnostic scanner that yields dynamic Doppler information from blood flow in addition to both static and dynamic echo information from stationary and more slowly moving tissues. The effect is produced by combining the flow imaging capability of a multigate pulse-Doppler flow detector with a fast rotational pulse-echo B-mode scanner. The duplex system was designed for performing ultrasonic echo-Doppler arteriography where the location and geometry of the interface between occlusive atherosclerotic tissue and blood is of prime concern. Initial results on normal arteries in vivo are illustrated. Spatial alignment of echo and Doppler images is obtained by using the same transducer and scanning mechanism for both. However, clinical trials on patients with verified occlusive arterial disease indicated a two-transducer system would be more desirable. It is concluded that superposition of images of both tissue and blood decreases the uncertainties inherent in the display of either image alone.     

Technique for the measurement of the amplitude and phase velocity of a slow space charge wave on a relativistic electron beam

A technique is described for the measurement of the axial electric field of a slow space charge wave. The measurement employs a double probe arranged to give an output proportional to the rate of change of magnetic flux linking the probe loop. This output may be related to the electric field of the wave. Two such probes used in an interferometer arrangement allow for the measurement of the phase velocity of the wave.     

Brain and plasma levels of cocaine and benzoylecgonine in lead-expose and cadmium-exposed rats following acute or chronic intraperitoneal administration of cocaine

We have cloned a full length cDNA coding for the activin type IIB receptor (GactRIIB) from the goldfish ovary. GactRIIB shares 73 and 70% amino acid identity in the extracellular domain, and 78 and 80% identity in the intracellular domain with the type IIB receptors of the mouse and Xenopus respectively. The intracellular domain of GactRIIB contains two serine kinase consensus sequences, DFKSRN and GTRRYMAPE, in agreement with the reports in other vertebrates that serine/threonine phosphorylation is involved in activin signal transduction. The identity of GactRIIB was confirmed by transient expression in the COS cells followed by activin binding. Iodinated human activin A bound to the GactRIIB-transfected cells and the binding could be completely inhibited by unlabeled activin. Affinity labeling revealed a band of about 85 kDa, which is in agreement with the reported type II receptors in other vertebrates. Together with the fact that activin is expressed in the goldfish ovary, the cloning of activin receptors from the ovary suggests paracrine and autocrine roles for activin in the goldfish ovarian functions.     

Parallel fiber-optic SCI links

Parallel fiber-optic links promise to be a key enabling technology for distributed computing, substantially increasing transmission distance and bandwidth. The drive to include more and more processors and I/O devices in parallel-processor complexes has created a need for box-to-box interconnection links capable of delivering bandwidth comparable to system backplanes. Point-to-point links overcome the speed and cost constraints of shared buses. However, copper-based point-to-point links can reliably carry high-speed data only a limited distance. Parallel fiber-optic links substantially increase transmission distance and surpass copper's bandwidth capability. Our research addresses the integration of parallel fiber-optic data links into system designs that require a high-bandwidth link over moderate distances. To demonstrate the feasibility of using parallel fiber-optic technology as a fundamental building block in large-scale commercial and parallel machines, we constructed a link testbed