Showing posts with label deSolve. Show all posts
Showing posts with label deSolve. Show all posts

Tuesday, 13 November 2012

Simulating neurons or how to solve delay differential equations in R

I discussed earlier how the action potential of a neuron can be modelled via the Hodgkin-Huxely equations. Here I will present a simple model that describes how action potentials can be generated and propagated across neurons. The tricky bit here is that I use delay differential equations (DDE) to take into account the propagation time of the signal across the network.

My model is based on the paper: Epileptiform activity in a neocortical network: a mathematical model by F. Giannakopoulos, U. Bihler, C. Hauptmann and H. J. Luhmann. The article presents a flexible and efficient modelling framework for:
  • large populations with arbitrary geometry
  • different synaptic connections with individual dynamic characteristics
  • cell specific axonal dynamics

Sunday, 11 September 2011

LondonR, 7 September 2011

On 7 September 2011 I attended the London R user group meeting. It was a very good turn out with about 50 attendees at the Shooting Star, a pub close to Liverpool Street Station. The session started at 18:00 with four presentations, followed by drinks sponsored by Mango Solutions. The slides of the presentation are available on londonr.org.

The first presentation was given by Lisa Wainer from UCL Department of Security and Crime Science about crime data analysis using R. Lisa presented about a project with Merseyside police, where she had built software, in R with the gWidgets package, called the Hot Products Early Warning System, that is used to help understand and characterise the acquisitive crime problem in Merseyside on an ongoing basis, detecting emerging trends in hot products.

Chris Wood gave an insightful talk about his research on sediment biogeochemical modelling in the North Sea. His model uses a set differential equations with over 20 parameters. Chris is able to analyse and fit his model to data he gathered on an expedition in the North Sea using R, the deSolve package and having access to the super-computer at the University of Southampton. How cool is this?

Jean-Robert Avettand-Fenoel talked about the Rook package and how R and Rook has helped him to roll out new applications to his colleagues faster than using Excel, VBA and C++ or RExcel. Rook allows you to build web apps with R. The package is maintained by Jeffery Horner, who also brought us the brew package. The brew allows us, in combination with Rapache, to mix html and R code in the same file. This is quite similar to the approach taken by Sweave for LaTeX and R. However, Rook provides a way to run R web applications on your desktop with the new internal R web server named Rhttpd.

The final presentation was actually given by myself talking about the googleVis package and the recent developments in version 0.2.9: