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October 12, 1999; 96 (21)
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Cover image: Ordered segregation arises from chaos. Granular particles with the same density but different sizes self-organize during experimental chaotic tumbling. The smallest beads concentrate in non-chaotic islands (blue), whereas the larger beads are found in chaotic regions (green). A similar separation pattern is seen with particles of the same size but different densities. See article by Hill et al. on pages 11701–11706 of this issue.

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October 12, 1999; 96 (21)
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