Implementing efficient concerted rotations using Mathematica and C code

In this article we demonstrate a general and efficient metaprogramming implementation of concerted rotations using Mathematica. Concerted rotations allow the movement of a fixed portion of a polymer backbone with fixed bending angles, like a protein, while maintaining the correct geometry of the backbone and the initial and final points of the portion fixed. Our implementation uses Mathematica to generate a C code which is then wrapped in a library by a Python script. The user can modify the Mathematica notebook to generate a set of concerted rotations suited for a particular backbone geometry, without having to write the C code himself. The resulting code is highly optimized, performing on the order of thousands of operations per second

Constributions of subterranean termites to the "economy" of Chihuahua desert ecosystems

We examined the role of subterranean termites in decomposition of cattle dung, various herbaceous plant species and wood in a Chihuahuan desert ecosystem. From July-September, termites remove dung at a rate of 0.63 g day-1 accounting for a percent mass loss of 19.5-100%. During the autumm subterranean termites consumed more than 50% of the leaves of the shrub Larrea tridentata, the grass Erioneuron pulchellum and annual plant Lepidium lasiocarpum and Baileya multiradiata but used very little of two other annuals eriastrum diffusum and Eriogonum trichopes. Yucca inflorescence stalks on plots with termites lost 23% of their original mass in 30 months while those on termite free soils los 11%. Elimination of termites resulted in reduction of fluff grass, Erioneuron pulchellum biomass, thereby affecting the structure of the ecosystem

Decomposition patterns of surface leaf of six plant species along a Chihuahua desert watershed

Mass losses from litter bags of surface creosote bush litter placed along a Chihuahuan Desert watershed were measured to answer the following questions: (1) Do edaphic factors affect organic matter losses? (2) Are there differences in mass losses between the litter of the site-dominant plant species and creosote bush leaf litter? We hypothesized that (1) mass losses of all litter types would be higher at the base of the watershed and lower on the upper portions of the watershed and (2) mass losses of the litter of the site-dominant plants would be higher than those of creosote bush leaf litter in the same site. Mass losses from creosote bush leaf litter did not follow the moisture-organic matter gradient present in the watershed. Mass losses were higher at mid-slope run-on areas than in upper-slope erosional sites and the dry lake basin. Mass losses were highest where subterranean termite activity was the highest. There were differences between losses from the litter of the site-dominant and creosote bush leaf litter in some instances, but these differences were not attributable to differences in lignin content nor C:N ratio. Mass losses of litter of site-dominant species were not always higher than that of creosote bush leaf litter in the same site. Mass losses were best described by the double exponential model