46 research outputs found

    Sensitivity analysis of reactive ecological dynamics

    Get PDF
    Author Posting. © Springer, 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Bulletin of Mathematical Biology 70 (2008): 1634-1659, doi:10.1007/s11538-008-9312-7.Ecological systems with asymptotically stable equilibria may exhibit significant transient dynamics following perturbations. In some cases, these transient dynamics include the possibility of excursions away from the equilibrium before the eventual return; systems that exhibit such amplification of perturbations are called reactive. Reactivity is a common property of ecological systems, and the amplification can be large and long-lasting. The transient response of a reactive ecosystem depends on the parameters of the underlying model. To investigate this dependence, we develop sensitivity analyses for indices of transient dynamics (reactivity, the amplification envelope, and the optimal perturbation) in both continuous- and discrete-time models written in matrix form. The sensitivity calculations require expressions, some of them new, for the derivatives of equilibria, eigenvalues, singular values, and singular vectors, obtained using matrix calculus. Sensitivity analysis provides a quantitative framework for investigating the mechanisms leading to transient growth. We apply the methodology to a predator-prey model and a size-structured food web model. The results suggest predator-driven and prey-driven mechanisms for transient amplification resulting from multispecies interactions.Financial support provided by NSF grant DEB-0343820, NOAA grant NA03-NMF4720491, the Ocean Life Institute of the Woods Hole Oceanographic Institution, and the Academic Programs Office of the MIT-WHOI Joint Program in Oceanography

    The Physics of the B Factories

    Get PDF

    Surface carboxymethylation of a chitin hydrogel

    No full text
    Journal of Bioactive and Compatible Polymers123208-220JBCP

    Examination of the factors involved in the choice of surgical implant materials

    No full text

    The influence of anionic chitin derivatives on calcium phosphate crystallization

    No full text
    10.1016/S0142-9612(98)00046-5Biomaterials19141309-1316BIMA

    Reversible water-swellable chitin gel

    No full text
    Journal of Polymer Science, Part A: Polymer Chemistry35102049-2053JPAC

    Promotion of calcification on carboxymethylchitin discs

    No full text
    10.1016/0142-9612(96)89778-XBiomaterials17151529-1534BIMA
    corecore