This example demonstrates a force-directed layout with radial foci, where mouse movement generates nodes that are attracted to invisible rings around the center. Node color encodes the ring’s squared radius using a linear color scale. The code uses d3.layout.force, svg selection of circles, and d3.svg.mouse to add nodes, while the tick handler steers each node toward its assigned ring distance. A transition shrinks nodes after three seconds and removes them from the array, creating a continuous particle stream. The work is derived from an earlier quantitative-foci example by Mike Bostock.