SPEEDSim: Spatial Population Dynamics Simulator 2.6

Spatial Population Ecological and Epidemiological Dynamics Simulator (SPEED Sim)

The Spatial Population Ecological and Epidemiological Dynamics Simulator (SPEED Sim) is a tool that facilitates hands-on interactive exploration of the spatial dynamics of various computational models in population ecology and epidemiology. The application also offers several cellular automaton models as an introduction to these types of simulations.

This application has been utilized in various K-12 educational outreach settings, including:

• Expanding Your Horizons workshops to foster interest in STEM fields among middle-school girls
• 4-H workshops for middle- and high-school students
• Workshop at the Maine Science Festival
• Several visits to K-12 schools
• An exhibit at the Maine Discovery Museum, a children's museum located in Bangor, Maine

The application currently features twelve different models:

1. Conway's Game of Life: a classic cellular automaton devised by mathematician John Conway in 1970
2. Vants (Langton's Virtual Ants): illustrates how highly intricate behaviors can stem from straightforward rules
3. Majority/Voter: models peer pressure, genetic drift, or the dissemination of opinions and ideas
4. Diffuse: a physics model depicting particles randomly diffusing (e.g., ink particles in a water jar)
5. Diffusion-Limited Aggregation: replicates a process akin to crystallization, where diffusing particles aggregate out of solution
6. Cyclic Cellular Automaton: a generalized version of 'rock-paper-scissors'
7. SIRS epidemiological model (Susceptible-Infectious-Recovered-Susceptible): demonstrates an infectious disease's spread through a population with individuals experiencing temporary immunity post recovery
8. Dispersal2: a population model where individuals disperse their offspring at two local scales
9. Fragmented Landscape: a population model featuring local and long-distance dispersal on a spatially structured heterogeneous landscape
10. Competitive Species: an extension of the Fragmented Landscape model, illustrating two species vying for available habitat using distinct strategies
11. Block Disturbance: a spatial population ecology model where individual births occur while death leads to simultaneous extinction of entire site blocks
12. Vaccinated Communities epidemiological model: showcases how vaccination levels across different communities impact infectious disease dynamics in addition to the total vaccination rate in a population
13. Internet Worms: simulates the propagation of malicious software through the internet using biologically inspired dispersal strategies

The simulation models enable users to modify all parameters influencing the dynamics. Detailed spatial dynamics images and time-based behavior summarizing graphs can be viewed and saved to the Photos library. Users can interactively draw new patterns by moving their finger across the lattice system. Additionally, pinch-to-zoom functionality and panning with two fingers are supported.

Most models allow loading images from the camera for simulations. To do so, tap on the Options menu at the bottom of the Lattice screen to load images from the camera or Photos library. For instance, with the Diffuse model, activating Walls mode in the Parameters tab allows running the model on an uploaded photo.

Note that the simulations are computationally demanding and perform faster on more recent iOS devices or when utilizing smaller lattice sizes. A speed adjuster accessible from the Options menu near the bottom of the Lattice screen permits users to slow down the simulation for detailed observation. The larger iPad screen offers an enhanced interface experience, although full functionality is ensured on iPhones and iPod Touches.

This work is supported by the National Science Foundation under Grant Nos. DMS-0718786 and DMS-0746603 awarded to David Hiebeler.