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450 results on '"Mitchell, James G."'

3. Hydrodynamic drift ratchet scalability

Author

Herringer, James, Lester, Daniel, Dorrington, Graham E., Mitchell, James G., and Rosengarten, Gary

Subjects
Physics - Fluid Dynamics
Abstract

The rectilinear "drift" of particles in a hydrodynamic drift ratchet arises from a combination of diffusive motion and particle-wall hydrodynamic interactions, and is therefore dependent on particle diffusivity, particle size, the amplitude and frequency of fluid oscillation and pore geometry. Using numerical simulations, we demonstrate that the drift velocity relative to the pore size is constant across different sized drift ratchet pores, if all the relevant non-dimensional groups (Peclet number, Strouhal number and ratio of particle to pore size) remain constant. These results clearly indicate for the first time the scaling parameters under which the drift ratchet achieves dynamic similarity, and so facilitates design, fabrication and testing of drift ratchets for experiments and eventually as commercial micro/nano fluidic separation devices., Comment: 17 pages, 10 figures

Published
2016

6. The Role of Diatom Nanostructures in Biasing Diffusion to Improve Uptake in a Patchy Nutrient Environment

Author

Mitchell, James G, Seuront, Laurent, Doubell, Mark J, Losic, Dusan, Voelcker, Nicolas H, Seymour, Justin, and Lal, Ratnesh

Subjects
Biological Sciences, Ecology, Biological Transport, Cell Membrane, Cell Wall, Diatoms, Diffusion, Environment, Extracellular Space, Nanostructures, Phytoplankton, General Science & Technology
Abstract

BackgroundDiatoms are important single-celled autotrophs that dominate most lit aquatic environments and are distinguished by surficial frustules with intricate designs of unknown function.Principal findingsWe show that some frustule designs constrain diffusion to positively alter nutrient uptake. In nutrient gradients of 4 to 160 times over

Published
2013

20. Supplementary information for the manuscript from Shifts in evolutionary balance of phenotypes under environmental changes

Author

Kleshnina, Maria, McKerral, Jody C., González-Tokman, Cecilia, Filar, Jerzy A., and Mitchell, James G.

Abstract

Environments shape communities by driving individual interactions and the evolutionary outcome of competition. In static, homogeneous environments a robust, evolutionary stable, outcome is sometimes reachable. However, inherently stochastic, this evolutionary process need not stabilize, resulting in a dynamic ecological state, often observed in microbial communities. We use evolutionary games to study the evolution of phenotypic competition in dynamic environments. Under the assumption that phenotypic expression depends on the environmental shifts, existing periodic relationships may break or result in formation of new periodicity in phenotypic interactions. The exact outcome depends on the environmental shift itself, indicating the importance of understanding how environments influence affected systems. Under periodic environmental fluctuations, a stable state preserving dominant phenotypes may exist. However, rapid environmental shifts can lead to critical shifts in the phenotypic evolutionary balance. This might lead to environmentally favoured phenotypes dominating making the system vulnerable. We suggest that understanding of the robustness of the system’s current state is necessary to anticipate when it will shift to a new equilibrium via understanding what level of perturbations the system can take before its equilibrium changes. Our results provide insights in how microbial communities can be steered to states where they are dominated by desired phenotypes.

Published
2022
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31. Synergetic impacts of turbulence and fishing reduce ocean biomass

Author

McKerral, Jody C., primary, Seymour, Justin R., additional, Lavery, Trish J., additional, Rogers, Paul J., additional, Jeffries, Thomas C., additional, Paterson, James S., additional, Roudnew, Ben, additional, Huveneers, Charlie, additional, Newton, Kelly, additional, van Dongen-Vogels, Virginie, additional, Cribb, Nardi P., additional, Winn, Karina M., additional, Smith, Renee J., additional, Beckmann, Crystal L., additional, Prime, Eloise, additional, Charlton, Claire M., additional, Kleshnina, Maria, additional, Grigson, Susanna R., additional, Takeuchi, Marika, additional, Seuront, Laurent, additional, and Mitchell, James G., additional

Published
2021
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45. High-resolution fluorometer for mapping microscale phytoplankton distributions

Author

Doubell, Mark J., Seuront, Laurent, Seymour, Justin R., Patten, Nicole L., and Mitchell, James G.

Subjects
Phytoplankton -- Research, Fluorescence -- Analysis, Biological sciences
Abstract

A new high-resolution, in situ profiling fluorometer maps fluorescence distributions with a spatial resolution of 0.5 to 1.5 mm to a depth of 70m in the open ocean. Centimeter-scale patterns for phytoplankton distributions associated with gradients exhibiting 10- to 30- fold changes in fluorescence in contrasting marine ecosystems are reported.

Published
2006

48. Confined aquifers as viral reservoirs

Author

Smith, Renee J., Jeffries, Thomas C., Roudnew, Ben, Seymour, Justin R., Fitch, Alison J., Simons, Keryn L., Speck, Peter G., Newton, Kelly, Brown, Melissa H., and Mitchell, James G.

Published
2013
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