indii::fmri::hemodynamic::LogFlowBalloonModel

LogFlowBalloonModel Class Reference

Inherits BalloonModel.

Inheritance diagram for LogFlowBalloonModel:

Inheritance graph
[legend]
List of all members.

Detailed Description

Balloon model driven by blood flow, and working in log space.

Author:
Lawrence Murray <lawrence@indii.org>
Version:
Rev
285
Date:
Date
2007-07-20 17:25:40 +0100 (Fri, 20 Jul 2007)
This class modifies FlowBalloonModel so that $v$ and $q$ vary in log space as:

\begin{eqnarray*} \frac{d \ln q}{dt} &=& \frac{\dot{q}}{q} \\ \frac{d \ln v}{dt} &=& \frac{\dot{v}}{v} \end{eqnarray*}

References to $q$ and $v$ in biophysical functions are substituted with the identities $q = e^{\ln q} $ and $v = e^{\ln v}$.

Working in log space ensures that $q$ and $v$ are always positive. This is particularly important in a stochastic setting, where noise may otherwise cause them to become negative, such as in the case of the Wiener process or discretised Gaussian noise. Introducing such noise into the log space instead ensures positivity.

See also:
FlowBalloonModel for more information on the usage of this model.

Definition at line 41 of file LogFlowBalloonModel.hpp.

Public Types

enum  StateVariable { LN_Q, LN_V }
 State variables. More...
enum  BiophysicalParameter { V_0, E_0, TAU_0, ALPHA }
 Parameter indices. More...
enum  BiophysicalFunction { F_IN, F_OUT, E }
 Function indices. More...

Public Member Functions

 LogFlowBalloonModel ()
 Create new model with default biophysical parameters and functions as defined in LogFlowBalloonModelDefaults and FlowBalloonModelDefaults.
virtual ~LogFlowBalloonModel ()
 Destructor.
virtual indii::ml::aux::vector suggestInitialState ()
 Provide a suggested initial state.
virtual void calculateDerivatives (double t, const double y[], double dydt[])
 
See also:
indii::ml::ode::DifferentialModel

Member Enumeration Documentation

enum StateVariable

State variables.

Enumerator:
LN_Q  $\ln(q) = \ln\left(\frac{Q(t)}{Q_0}\right)$; natural logarithm of the normalised dHb content at the current time.
LN_V  $\ln(v) = \ln\left(\frac{V(t)}{V_0}\right)$; natural logarithm of the normalised volume at the current time.

Definition at line 46 of file LogFlowBalloonModel.hpp.

enum BiophysicalParameter

Parameter indices.

These match those of FlowBalloonModel for consistency.

Enumerator:
V_0  $V_0$; volume of the venous compartment at rest.
E_0  $E_0$; oxygen extraction rate of the venous compartment at rest.
TAU_0  $\tau_0 = \frac{V_0}{F_0}$; mean transit time through the venous compartment at rest.
ALPHA  $\alpha$; Grubb's exponent.

Definition at line 64 of file LogFlowBalloonModel.hpp.

enum BiophysicalFunction

Function indices.

These match those of FlowBalloonModel for consistency.

Enumerator:
F_IN  $f_{in}(t) = \frac{F_{in}(t)}{F_0}$; normalised flow into the venous compartment.
F_OUT  $f_{out}(t) = \frac{F_{out}(t)}{F_0}$; normalised flow out of the venous compartment.
E  $E(t)$; oxygen extraction rate of the venous compartment.

Definition at line 92 of file LogFlowBalloonModel.hpp.

Constructor & Destructor Documentation

LogFlowBalloonModel (  ) 

Create new model with default biophysical parameters and functions as defined in LogFlowBalloonModelDefaults and FlowBalloonModelDefaults.

Definition at line 13 of file LogFlowBalloonModel.cpp.

~LogFlowBalloonModel (  )  [virtual]

Destructor.

Definition at line 27 of file LogFlowBalloonModel.cpp.

Member Function Documentation

aux::vector suggestInitialState (  )  [virtual]

Provide a suggested initial state.

This can be passed to the constructor of the ordinary differential equation solver being used on the model, such as indii::ml::ode::AdaptiveRungeKutta.

Returns:
Suggested initial state for the system.

Implements BalloonModel.

Definition at line 41 of file LogFlowBalloonModel.cpp.

void calculateDerivatives ( double  t,
const double  y[],
double  dydt[] 
) [virtual]

See also:
indii::ml::ode::DifferentialModel

Definition at line 31 of file LogFlowBalloonModel.cpp.

The documentation for this class was generated from the following files:
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