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Physical Sciences and Mathematics Commons

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Full-Text Articles in Physical Sciences and Mathematics

Morphological Biosignatures And The Search For Life On Mars, Sherry L. Cady, Jack D. Farmer, John P. Grotzinger, J. William Schopf, Andrew Steele Jun 2003

Morphological Biosignatures And The Search For Life On Mars, Sherry L. Cady, Jack D. Farmer, John P. Grotzinger, J. William Schopf, Andrew Steele

Geology Faculty Publications and Presentations

This report provides a rationale for the advances in instrumentation and understanding needed to assess claims of ancient and extraterrestrial life made on the basis of morphological biosignatures. Morphological biosignatures consist of bona fide microbial fossils as well as microbially influenced sedimentary structures. To be recognized as evidence of life, microbial fossils must contain chemical and structural attributes uniquely indicative of microbial cells or cellular or extracellular processes. When combined with various research strategies, high-resolution instruments can reveal such attributes and elucidate how morphological fossils form and become altered, thereby improving the ability to recognize them in the geological record …


Hillslope Nutrient Dynamics Following Upland Riparian Vegetation Disturbance, J. Alan Yeakley, David C. Coleman, Bruce L. Haines, Brian D. Kloeppel, Judy L. Meyer, Wayne T. Swank, Barry W. Argo, James M. Deal, Sharon F. Taylor Mar 2003

Hillslope Nutrient Dynamics Following Upland Riparian Vegetation Disturbance, J. Alan Yeakley, David C. Coleman, Bruce L. Haines, Brian D. Kloeppel, Judy L. Meyer, Wayne T. Swank, Barry W. Argo, James M. Deal, Sharon F. Taylor

Environmental Science and Management Faculty Publications and Presentations

We investigated the effects of removing near-stream Rhododendron and of the natural blowdown of canopy trees on nutrient export to streams in the southern Appalachians. Transects were instrumented on adjacent hillslopes in a first-order watershed at the Coweeta Hydrologic Laboratory (35°03′N, 83°25′W). Dissolved organic carbon (DOC), K+, Na+, Ca2+, Mg2+, NO3-- -N, NH4+ -N, PO43---P, and SO42- were measured for 2 years prior to disturbance. In August 1995, riparian Rhododendron on one hillslope was cut, removing 30% of total woody biomass. In October …


Ordering Genetic Algorithm Genomes With Reconstructability Analysis, Stephen Shervais, Martin Zwick Jan 2003

Ordering Genetic Algorithm Genomes With Reconstructability Analysis, Stephen Shervais, Martin Zwick

Systems Science Faculty Publications and Presentations

The building block hypothesis implies that genetic algorithm effectiveness is influenced by the relative location of epistatic genes on the chromosome. We find that this influence exists, but depends on the generation in which it is measured. Early in the search process it may be more effective to have epistatic genes widely separated. Late in the search process, effectiveness is improved when they are close together. The early search effect is weak but still statistically significant; the late search effect is much stronger and plainly visible. We demonstrate both effects with a set of simple problems, and show that infonnation-theoretic …