Model creation
- Either via graphical model designer or a text editor
- Chemical reaction based (ODE creation done by the PottersWheel chemical compiler)
- ODE based (optionally with reaction network reconstruction)
- Import from SBML model or a regular custom structure
- Rule based modeling to cope with combinatorial complexity
- Algebraic equations (assignment rules, start value assignments)
- Support of model families without redundant modeling
Model integration
- The differential equations of a model are dynamically compiled as C files
- 14 integrators supported (6 FORTRAN, 7 Matlab, 1 C)
- Very fast model integration allows for a real time modeling and fitting experience
Model investigation
- Equalizer allows to change parameter values via sliders in real time
- Input Designer allows to change the characteristics of external driving functions, like a continuous, pulsed, or ramp stimulation
- Automatic investigations like sensitivity analyses including control coefficients
External driving input
- Strong support of external input functions which drive the dynamical system
- Input is either given analytically or based on experimental data
Experimental data
- Strong support to incorporate external data saved in MS Excel or ASCII format
- Automatic detection of data column names and mapping dialog for model observations
- Automatic use of already mapped data sets
- Support of multiple stimulations within one experiment
- Dose- or stimulus-dependent view possible
- Estimation of experimental standard deviation
- Outliers dialog to remove single data points after visual inspection
Fitting
- Support of powerful deterministic and stochastic optimization algorithms
- Multi-Experiment fitting: One model is fitted simultaneously to several data sets. Parameters with a unique or data set depending meaning are distinguished.
- Several fit sequences available, like n fits each starting from the last fit with disturbed parameter values
- Fit sequence starting from locations within the complete parameter space
- Qualitative or soft constraints can be specified
- Fit sequences can be run on a cluster using the parallel computing toolbox
Fit sequence analysis
- Best fit selection
- Histograms and box plots of fitted parameter values
- Linear correlation analysis including principal component analysis (PCA) in order to detect linear non-identifiabilities (see Plug Ins section for detection of non-linear non-identifiabilities)
- Hierarchical clustering of the parameter space
- Analyis of custom derived parameters, which are functions of parameters
- ScatterMan: Manual investigation of pairs and triples of fitted parameter values
Single fit analysis
- Detailed residual analysis
- Statistical tests for chi square values
Reporting
- Each analysis or fit can be appended as a section to a report
- Optional with graphical model visualization and a list of reactions
- The order of sections can be changed at any time
- All figures of a section can separately be investigated
- Support of PDF-Latex (recommended), MS Word, and HTML reports
Sessions
- The complete current working state can be saved and reloaded any time
- Exchange of sessions between researches to exactly reproduce modeling efforts
- A modeling session comprises an arbitray set of repository models and data sets and currently combined model-data couples for fitting
Application programming interface and macros
- Rich set of Matlab functions to use PottersWheel functionalities within custom Matlab programs
- Macros support an automated and documented way to model efficiently
- Comprehensive, uptodate documentation via 'help FunctionName' or online
Graphical user interfaces
- Modeling requires no Matlab knowledge due to many user friendly graphical interfaces
- Steep learning curve
- Modeler has more time to focus on modeling than on technical details
Plug Ins
- Stefan Hengl's MOTA algorithm in order to detect non-identifiabilities if an arbitrary number of model parameters share a linear or non-linear functional relationship (Data-Based Identifiability Analysis of Nonlinear Dynamical Models. Bioinformatics, 2007, 23: 2612-8)
- Andreas Raue's PLE algorithm to discriminate structural and practical non-identifiabilities and to determine correct parameter confidence intervals (Structural and practical identifiability analysis of partially observed dynamical models by exploiting the profile likelihood, Bioinformatics 2009, 25(15):1923-1929)
Requirements
- Matlab 7.1 SP3
- Optimization toolbox recommended
- Windows, Linux, or Macintosh
- The Windows OS may be 32 or 64 bit, but the installed Matlab version has to be 32 bit
