Despite the stunning diversity of leaf shapes from one plant variety to another, a universal formula may guide the vein patterns in all leaves. An analysis of leaf vein networks revealed simple relationships between the angles that veins form when they intersect and the thickness of the veins at the intersections. The universal similarity of vein structure from one plant to another suggests that the patterns provide insight to leaf mechanics, but are of little help in distinguishing or cataloging plants, thereby eliminating one proposed botanical cataloging scheme.

Physics News Update: http://www.aip.org/enews/physnews/2002/split/596-3.html
Journal article: http://link.aps.org/abstract/PRE/v65/e061914
Graphics: http://www.aip.org/mgr/png/2002/156.htm

2) Quantum entanglement in carbon nanotubes
C. Bena, S. Vishveshwara, L. Balents, M. P. A. Fisher
Physical Review Letters (Print issue: July 15, 2002)

Entangled pairs of particles, in which measuring the state of one simultaneously determines the state of the other, are a central part of proposed schemes for quantum cryptography and teleportation. One potential source of such particles is the stream of conjoined electrons that exist in superconductors, but no one has been able to drive a wedge between these so-called Cooper pairs. A new proposal suggests one possible separation method: send them down a pair of carbon nanotubes.

Physical Review Focus: http://focus.aps.org/v9/st33.html
Journal article: http://link.a
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Contact: David Harris
harris@aps.org
301-209-3238
American Physical Society
3-Jul-2002