Team:BCCS-Bristol/Modeling

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BCCS-Bristol
iGEM 2009

Contents

Workflow

  • Study Team:BCCS-Bristol/Modeling/Ideas to understand high level development goals (you can add stuff to that page!)
  • Decide the specifics of what needs to be done and add items to your to-do list. Ideally the items added should read like commit messages
  • Commit to the [http://code.google.com/p/bsim-bccs/ subversion repository] and strike out the item on your to-do list, adding a reference to the commit number if possible e.g:
    • Rename BSimObject to BSimParticle r19

Todo list

Steve

  • Abstract for ECCS (1st Sep)
  • Contact Paris team, review gold medal requirements
  • Analyse performance using TPTP, rerun BSim1.0 simulations w/o various collisions to assess statistical importance
  • Identify the most interesting parameters over which to plot a quality function


  • Simplify growth > vesiculation based on P_begin P_end
    • "Growth curves were measured for all of the mutants, and their log-phase doubling times were calculated. In general, more extreme vesiculation phenotypes corresponded to longer doubling times" (Outer Membrane Vesicle Production by Escherichia coli Is Independent of Membrane Instability)
  • Processing export libraries
  • CollisionPhysics > CollisionDetection/CollisionResponse?
  • Study whether 3D implementation of newPosition in BSimBacteriaCreate is reasonable r28
  • Refactor to use Vector and Matrix types from vecmath
  • tumbleSpeed looks a bit suspect
  • 3D diffusion for BSimChemicalField r29
  • Add paper references to parameter values in the code using page from last year
  • 3D tumbling in BSimBacteria r65
  • Improve knowledge of rigid body collisions [http://chrishecker.com/images/e/e7/Gdmphys3.pdf] [http://www.cs.lth.se/EDA046/lectures/L3.pdf]

Emily

  • Issue with bacteria 'escaping' the boundaries r61
    • When the bacteria have a large enough force and the time step is not small enough the bacteris are able to 'escape' the boundary.
    • Fix this by checking the distance and direction of all the bacteria close to the boundary. This will catch those that have crossed the boundary in one time step.
    • THIS COULD BE IMPROVED FURTHER - it allows for far greater forces however does not fix this problem in all cases.
  • Understand how bacteria "tumble" under magnetic force
    • It is believed that the magnetic force causes the bacteria to orientate in line with the field and so the tumble phase will not occur.
  • Implement directed bateria (bacteria under constant magnetic field)
    • Control only the direction of the bacteria - not the force. r116
    • Add some variation in the direction of each bacterium
      • The average alignment of the population is described by Langevin function for classical paramagnetism. [http://arjournals.annualreviews.org/doi/pdf/10.1146/annurev.mi.36.100182.001245]
      • The interaction of the population with a magnetic field is affected by the temperature.
  • Finish coding the magnetic force for variable magnetic force
    • Code the magnetic force as an additional force on the bacteria along with the internal and external forces. r82
    • Find realistic values for the magnetic force acting on the bacteria.
  • Code half-coated bead
    • Apply two different potentials to each half of the bead - one side has a potential well (the bacteria attach here) and the other side has no well (the bacteria will interact normally here).
  • Control which objects are affected by the magnetic force
    • Magnetotactic bacteria in a constant magnetic field
    • Magnetotactic bacteria in a variable magnetic field
    • E. coli attaching to a magnetic bead under a variable magnetic field

Antos

  • BSim GRNs
    • Proof of concept to check functionality. [http://www.pnas.org/content/101/30/10955 Something like this]
      • Update: it works! Run large scale simulation to check for long term synchronization...
    • Java implementation of Runge-Kutta 4th order solver. r70
      • Refactor ODEs from an interface to an abstract class if necessary.
    • Investigate other options in terms of external libraries (eg odeToJava - good but seems overcomplicated for current purposes; hundreds of lines of code for one solver routine)done
    • Implement the solvers into BSim. Done for single bacterium
    • Implement other solvers (more efficient). r70
      • The ability to choose between solvers (in BSim, not hard-coded).
      • Investigate possibility of using javax/vecmath and matrix ops to maybe make the larger routines more efficient.
    • Extend to Stochastic ODEs.
    • Interface BSim with external parameters (maybe similar to current parameter files) used to define an ODE system.
      • Investigate the feasibility of SBML parameters or a similar XML based format. SBML may be overcomplicated for our current needs. Low priority for now.
      • Similarly investigate the format used by XPP (may be more succinct, also is specifically for ODEs).
    • Investigate and implement GRN (ODE) and chemical field interaction.
      • Study implementation of 3D diffusion in BSim. Seems to work fine
      • Implement diffusion in/out terms for membrane diffusion.
    • GRN interaction with vesicle budding and chemical transport (on the surface of the vesicle and inside it).
    • Incorporate a method for seeing the effects of GRN activity (eg colour changes, pop-out time series).
  • New and updated BSim documentation?
  • BSim graphics
    • Rod shape rotation. r125
    • Basic BSimChemicalField drawing in 3D - will help with grns with a diffusing chemical. Done (r124) but needs to be improved in terms of speed
    • BSimChemicalField for 3 chemotaxis fields and GRN/quorum.
    • Investigate (OpenGL?) volume rendering (Tom - Vidi?) maybe better for arbitrary (GRN diffusion) chemical fields
  • GRNs and vesicles
    • Read more about the mechanics of different GRNs (specifically switches).
    • Find out how they interact with the external environment.
    • Investigate the possiblity of using a different time-step to the fixed one in BSim. Can use a longer or shorter time-step if required, however need to finish other parts to see if this would be relevant/important.
    • Investigate the effect of different time steps (GRNs operate on a time scale relatively long compared to that of BSim).
    • Investigate the mechanics of our GRNs with respect to vesicle budding and communication.
    • Investigate methods for numerically solving stochastic ODEs.

Mattia

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