The phenology of epiphytic diatoms and epifauna observed on Zostera marina of Arikawa Bay, Nagasaki Prefecture, Japan

We present a descriptive account of the dynamics of epiphytic diatoms, epifauna, and the leaf surface area of Zostera marina in a shallow water ecosystem. We hypothesized that the growth stage of the host macrophyte (i.e., leaf surface area) influenced the presence of epiflora and epifauna, as well as that the leaf surface area and epifaunal population density affected the cell density and species composition of epiphytic diatoms. To evaluate this hypothesis, we quantified the leaf surface area of a host macrophyte (Zostera marina), the presence of epifauna, and the community of epiphytic diatoms that could be observed on the leaves of Z. marina during the period from May 2017 to December 2018. We conducted a descriptive analysis of the time-series observations of leaf surface area, epiphytic diatom density, and epifauna population density. Epiphytic diatom density was low and epifauna density was high during the growing season of Z. marina. Epiphytic diatom density was high and epifauna density was low during the maturation and senescence periods of Z. marina. Our analysis shows that epifauna densities lagged epiflora densities by at least four months, and that epiflora densities lagged leaf area by four months. Therefore, we hypothesized that herbivorous gastropods and amphipods could alter species composition via their preference of food items (active choice) or by ingesting more of the species that were structurally more available (passive preference)

Global-local modeling for composites by the homogenization method.

The purpose of this thesis is to study the various issues in the constitutive modeling for composite materials by using the asymptotic homogenization method. Due to the global-local approach for mechanics of composites, the modeling issues are essential to characterize the overall mechanical behavior of a composite structure as well as the microstructures. Although all the subjects studied in this thesis are closely related to each other from the viewpoint of modeling the mechanical behavior of composites, it can be divided into two major parts. One is the constitutive modeling for composites with nonlinearity and coupling phenomena of solid and fluid phases in the microstructural level and the other is geometry modeling of microstructures in the homogenization analyses. While nonlinear problems such as elastoplasticity involve the coupling between the micro- and macroscopic mechanical behaviors, complicated phase interaction is observed in mixtures of solid and fluid. The homogenization procedure is based on the governing equations for the field variables defined in their microscopic levels. Therefore, once the microstructural model is appropriately defined for each constituent, the derived homogenized field equations, which coincide with those of existing theories in mathematical physics, explicitly reflect the micromechanical behavior. The global-local modeling in this study also involves the geometry modeling of the periodic microstructure. In order to study the specific effects of the microstructural morphology, the recently developed geometry modeling technique (by digital imaging) is utilized. While the feasibility and applicability of the image-based geometry modeling are examined from the engineering point of view, the convergence theory for the homogenization method enables its use in the analysis of not only periodic media but also random composites.Ph.D.Applied SciencesMaterials scienceMechanical engineeringMechanicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/129816/2/9624743.pd