MechanicalStimulusCalculator.cpp

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#include "Owen11Parameters.hpp"
#include "MechanicalStimulusCalculator.hpp"

template<unsigned DIM>
MechanicalStimulusCalculator<DIM>::MechanicalStimulusCalculator() : AbstractVesselNetworkCalculator<DIM>(),
    mTauRef(1.e-6 * unit::pascals),
    mTauP(0.05 * unit::pascals),
    mkp(Owen11Parameters::mpSensitivityToIntravascularPressure->GetValue("MechanicalStimulusCalculator"))
{

}

template<unsigned DIM>
MechanicalStimulusCalculator<DIM>::~MechanicalStimulusCalculator()
{

}

template <unsigned DIM>
boost::shared_ptr<MechanicalStimulusCalculator<DIM> > MechanicalStimulusCalculator<DIM>::Create()
{
    MAKE_PTR(MechanicalStimulusCalculator<DIM>, pSelf);
    return pSelf;
}

template<unsigned DIM>
units::quantity<unit::pressure> MechanicalStimulusCalculator<DIM>::GetTauP()
{
    return mTauP;
}

template<unsigned DIM>
units::quantity<unit::pressure> MechanicalStimulusCalculator<DIM>::GetTauReference()
{
    return mTauRef;
}

template<unsigned DIM>
void MechanicalStimulusCalculator<DIM>::SetTauRef(units::quantity<unit::pressure> TauRef)
{
    mTauRef = TauRef;
}

template<unsigned DIM>
void MechanicalStimulusCalculator<DIM>::SetTauP(units::quantity<unit::pressure> TauP)
{
    mTauP = TauP;
}

template<unsigned DIM>
void MechanicalStimulusCalculator<DIM>::Calculate()
{
    std::vector<boost::shared_ptr<VesselSegment<DIM> > > segments = this->mpNetwork->GetVesselSegments();

    units::quantity<unit::length> cm(0.01*unit::metres);
    units::quantity<unit::mass> g(1.e-3*unit::kg);
    units::quantity<unit::force> dyne(g*cm/(unit::seconds*unit::seconds));
    units::quantity<unit::pressure> dyne_per_centi_metre_squared(dyne/(cm*cm));
    for (unsigned idx = 0; idx < segments.size(); idx++)
    {
        // Get average pressure in a segment
        units::quantity<unit::pressure> node0_pressure = segments[idx]->GetNode(0)->GetFlowProperties()->GetPressure();
        units::quantity<unit::pressure> node1_pressure = segments[idx]->GetNode(1)->GetFlowProperties()->GetPressure();

        // Empirical Equation. Pressure in mmHg, WSS in dyne/cm2.
        units::quantity<unit::pressure> conversion_pressure(1.0*unit::mmHg);
        double average_pressure_in_mmHg = (node0_pressure + node1_pressure)/(2.0*conversion_pressure);

        // The calculation does not work for low pressures, so we need to specify a cut-off value.
        if (log10(average_pressure_in_mmHg) < 1.0)
        {
            mTauP = 1.4 * dyne_per_centi_metre_squared;
        }
        else
        {
            double inside_exponent = -5000.0*pow(log10(log10(average_pressure_in_mmHg)), 5.4);
            mTauP = (100.0 - 86.0 * exp(inside_exponent)) * dyne_per_centi_metre_squared;
        }

        // The equation is dimensionally inconsistent. Drop out of the units framework.
        double log_term_1 = log10((segments[idx]->GetFlowProperties()->GetWallShearStress()/dyne_per_centi_metre_squared + mTauRef/dyne_per_centi_metre_squared));
        double log_term_2 = log10(mTauP/dyne_per_centi_metre_squared);

        units::quantity<unit::rate> mechanical_stimulus = (log_term_1 - 0.5*log_term_2) * unit::per_second;
        segments[idx]->GetFlowProperties()->SetGrowthStimulus(segments[idx]->GetFlowProperties()->GetGrowthStimulus() + mechanical_stimulus);
    }
}

// Explicit instantiation
template class MechanicalStimulusCalculator<2> ;
template class MechanicalStimulusCalculator<3> ;