NetLogo User Community Models
by Joerg Hoehne (Submitted: 09/15/2004)
WHAT IS IT?
This model simulates a hypercycle described by Eigen and Schuster 1979. A hypercycle is a prebiotic model which shows how stable structures (e.g. life forms) can or will emerge because of cyclic support of self replicating molecules to other self replicating molecules. This model can simulate up to 10 different molecule types.
b) Every empty cell (patch) can be filled by a molecule of the surrounding neighbours (north, west, south, east) or remains empty.
c) Every molecule has in a cycle of a run a certain chance to reproduce itself. This is defined by the constant s[i] where [i] denotes the i_th entry for the corresponding molecule i. The value for every s[i] is 1.
d) Due to the hypercycle a molecule gets some support to reproduce itself if its predecessor is in the neighbourhood. This support value is 100 which raises the probability a molecule will reproduce itself into an empty cell.
e) Using a parasite molecule will give more support of one state to the parasite state as any other state will receive.
HOW IT WORKS
This model uses no turtles. The patches are the cells of the cellular automata. The models runs through every patch for which the next state will be computed. After all some sort of diffusion to simulate the molecule drift is computed by exchanging the next states of neigbour patches. After all next states have been computed als patches set these as the current state.
The state 0 (displayed black) denotes an empty patch. The state 1 (red) will denote a parasite molecule if the parasite option is activated.
The parasite will be simulated by changing the support values. Usually the support for 5 states is:
1 supports 2.
Introducing a parasite will change these rules to
For the general idea how this model works please refer to
HOW TO USE IT
Use the control elements from top to down and left to right. But read the following information first!
Doing a run:
THINGS TO NOTICE
Wait for the emerging spirals. This model may run very slowly but structures will emerge only with screen-sizes greater 50.
THINGS TO TRY
This section could give some ideas of things for the user to try to do (move sliders, switches, etc.) with the model.
EXTENDING THE MODEL
This section could give some ideas of things to add or change in the procedures tab to make the model more complicated, detailed, accurate, etc.
This section could point out any especially interesting or unusual features of NetLogo that the model makes use of, particularly in the Procedures tab. It might also point out places where workarounds were needed because of missing features.
This section could give the names of models in the NetLogo Models Library or elsewhere which are of related interest.
CREDITS AND REFERENCES
This model was developed by Joerg Hoehne in September 2004 in the intention to learn the concepts and programming features of NetLogo.
[Book, out of print] Eigen, Manfred ; Schuster, Peter: The Hypercycle - A Principle of Natural Self-Organization. Springer, 1979
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