(Georgia Institute of Technology, 1986-01-30)
Kolinski, Andrzej; Skolnick, Jeffrey; Yaris, Robert
We present preliminary results of Monte Carlo studies on the dynamics of multichain diamond-lattice systems at considerably greater densities than those done previously. Chain dynamics were simulated by a random sequence of three or four bond kink motions. The single bead autocorrelation function exhibits "slow" mode relaxation behavior with a g(t)∝ tβ. There is a smooth crossover from Rouse-like dynamics, β=1/2, at low density to smaller values of β at higher density and β=0 at the glass transition density (φG≅0.92). The simulation provides a self-diffusion coefficient D ∝ n-2, with n the number of beads, in agreement with experiment. A phenomenological model, different from the widely accepted reptation picture, is proposed.
(Georgia Institute of Technology, 1983-12)
Hay, Mark E.; Goertemiller, Tim
Transplanted sections of the seagrass Thalassia testudinum were used as a
bioassay to assess between-habitat differences in herbivory on three Caribbean
reefs. Consumption of Thalassia by herbivorous fishes on shallow (1-10 m) reef slopes was significantly higher than on deep (30-40 m) reef slopes or on shallow
reef flats. Seaweeds typical of reef flat habitats were rapidly consumed when
placed on shallow reef slopes. Seaweeds typical of either deep or shallow reef
slopes were relatively resistant to herbivory and a high proportion of these
species are known to contain secondary chemical compounds that appear to deter
herbivorous fishes. Shallow reef flats provide seaweeds with a predictable
spatial escape from major reef herbivores; algae characteristic of these habitats
have evolved few, if any, characteristics that significantly reduce losses to herbivory.