39 research outputs found

    Molecule Microscopy

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    Contains reports on summary of research and one research project.Joint Services Electronics Program (Contract DAAB07-75-C-1346)National Institutes of Health (Grant 5 S05 RR07047-10)National Institutes of Health (Grant 5 PO1 HL14322-05)National Institutes of Health (Grant 1 ROI GM22633-01

    Molecular Beams

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    Contains research objectives and reports on five research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Institutes of Health (Grant 5 S05 FR07046-06)Public Health Service Research Grant 1 P01 HL14322-01 from the National Heart and Lung Institute to the Harvard-M. I. T. Program in Health Services and Technolog

    Molecular Beams

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    Contains research objectives, summary of research and reports on eight research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-030

    Disturbance Alters the Phylogenetic Composition and Structure of Plant Communities in an Old Field System

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    The changes in phylogenetic composition and structure of communities during succession following disturbance can give us insights into the forces that are shaping communities over time. In abandoned agricultural fields, community composition changes rapidly when a field is plowed, and is thought to reflect a relaxation of competition due to the elimination of dominant species which take time to re-establish. Competition can drive phylogenetic overdispersion, due to phylogenetic conservation of ‘niche’ traits that allow species to partition resources. Therefore, undisturbed old field communities should exhibit higher phylogenetic dispersion than recently disturbed systems, which should be relatively ‘clustered’ with respect to phylogenetic relationships. Several measures of phylogenetic structure between plant communities were measured in recently plowed areas and nearby ‘undisturbed’ sites. There was no difference in the absolute values of these measures between disturbed and ‘undisturbed’ sites. However, there was a difference in the ‘expected’ phylogenetic structure between habitats, leading to significantly lower than expected phylogenetic diversity in disturbed plots, and no difference from random expectation in ‘undisturbed’ plots. This suggests that plant species characteristic of each habitat are fairly evenly distributed on the shared species pool phylogeny, but that once the initial sorting of species into the two habitat types has occurred, the processes operating on them affect each habitat differently. These results were consistent with an analysis of correlation between phylogenetic distance and co-occurrence indices of species pairs in the two habitat types. This study supports the notion that disturbed plots are more clustered than expected, rather than ‘undisturbed’ plots being more overdispersed, suggesting that disturbed plant communities are being more strongly influenced by environmental filtering of conserved niche traits

    Surgical Critical Care:Vol 1

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    Surgical Critical Care:Vol 2

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