This paper describes an experimental study of three perceptual properties of motion: flicker, direction, and velocity. Our goal is to understand how to apply these properties to represent data in a visualization environment. Results from our experiments show that all three properties can encode multiple data values, but that minimum visual differences are needed to ensure rapid and accurate target detection: flicker must be coherent and must have a cycle length of 120 milliseconds or greater, direction must differ by at least 20/spl deg/, and velocity must differ by at least 0.43/spl deg/ of subtended visual angle. We conclude with an overview of how we are applying our results to real-world data, and then discuss future work we plan to pursue.

Ring topology local area networks (LAN's) using the "buffer insertion" access method have as yet received relatively little attention. In this paper we present details of a LAN of this,type, called SILK-system for integrated local communication (in German, "Kommunikation"). Sections of the paper describe the synchronous transmission technique of the ring channel, the time-multiplexed access of eight ports at each node, the "braided" interconnection for bypassing defective nodes, and the role of interface transformation units and user interfaces, as well as some traffic characteristics and reliability aspects. SILK's modularity and open system concept are demonstrated by the already implemented applications such as distributed text editing, local telephone or teletex exchange, and process control in a TV studio.