Deployable membranes designed from folding tree leaves.

A simple model of deploying tree leaves is assembled in different arrangements to produce polygonal foldable membranes for use as deployable structures. One family of folding patterns exhibits a small strain mechanism, which is investigated. Variations on the basic arrangements can be used to fold membranes with a discretized curvature.

A tree-ring perspective on the extreme wetness of the early 1900’s in the western United States [abstract]

Ring-width indices from 136 sites in the area from northern Montana to southern New Mexico between latitudes 103°W and 111°W were examined to infer periods of anomalous wetness for the years 1700-1964. Sites were grouped into north, central and south regions, and the gross regional tree-ring fluctuations were compared. The results indicate that the period 1905-1917 was unique in the 265-year record for the combined magnitude, duration, and north/south coherence of the growth anomaly of much lesser magnitude occurred in the 1830's-1840's [sic]. Both this and the 1905-1917 anomaly appear from time-series plots to be manifestations of low-frequency growth variations at wave lengths between about 20 and 60 years.

400 years of precipitation variability in central and southern California reconstructed from tree-rings [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Precipitation variability at 31 stations hanging from San Diego to San Francisco and from the coast to the Sierras was characterized ...