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Plant species vary widely in their average leaf lifespan (LL) and specific leaf area (SLA, leaf area per dry mass). The negative LL–SLA relationship commonly seen among species represents an important evolutionary trade-off, with higher SLA indicating greater potential for fast growth (higher rate of return on a given investment), but longer LL indicating a(More)
1. Biological soil crusts (biocrusts) occur across most of the world's drylands and are sensitive indicators of dryland degradation. Accounting for shifts in biocrust composition is important for quantifying integrity of arid and semi-arid ecosystems, but the best methods for assessing biocrusts are uncertain. We investigate the utility of surveying(More)
Li, K. C. (1992). On principal Hessian directions for data visualization and dimension reduction: another application of Stein's lemma. (1991). A bias bound for applying linear regression to a general linear model. (1992). Measurement error regression with unknown link: dimension reduction and data visualization. On almost linearity of low dimensional(More)
The core region of the Xenopus laevis pre-ribosomal RNA promoter was subjected to point mutation analysis. A total of 27 point mutants within a 78 base pair region from -64 to +14, (relative to the start of transcription at +1), were assayed by oocyte microinjection. The results locate the 3' boundary of the core promoter at +4 and the 5' boundary at(More)
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