Finding differences amongst a system of differential equations

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Discussion Overview

The discussion revolves around the differences between two systems of differential equations modeling the dynamics of T-cells and virus interactions in the context of HIV infection. Participants are examining the implications of specific terms included or excluded in the equations, focusing on their biological significance and the sources of these equations.

Discussion Character

  • Homework-related
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Post 1 outlines the two systems of equations and highlights differences, specifically the presence of the term $$\pi E$$ in System 1 and its absence in System 2, questioning the biological rationale behind this.
  • Post 2 suggests that both referenced sources (Otto and Science) omitted the term $$-\beta VR$$ in the equation for virus dynamics, but acknowledges that the original poster included it in their equations.
  • Post 2 also explains that the term $$-\pi E$$ does not appear in the equation for $$dE/dt$$ because the infected cells produce virus particles without being removed, referencing Box 2.4 from Otto.
  • Post 3 reiterates the points made in Post 2, emphasizing the importance of checking the equations by summing them up to verify consistency with the biological model.
  • Post 5 questions the correctness of the equation for $$dE/dt$$ and seeks clarification on the differences in the equations, indicating uncertainty about the implications of the terms involved.

Areas of Agreement / Disagreement

Participants express differing views on the significance of specific terms in the equations, with some siding with the interpretations from the referenced sources while others defend their own formulations. The discussion remains unresolved regarding the correctness and implications of the equations presented.

Contextual Notes

There are references to specific sections in the literature that may contain assumptions or claims about the negligible impact of certain terms, but these claims are not universally accepted within the discussion. The participants are also navigating the complexities of biological modeling, which may involve varying interpretations of the equations.

J6204
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Homework Statement


Given the following figure and the following variables and parameters, I have been able to come up with the set of differential equation below the image. My question is how does the system of equations 1 which I produced myself differ from the set of equations 2. Below I have a further explanation of this question. The image below was used to create my system of equations 1.

Homework Equations


Variables
R(t): number of susceptible T-cells
L(t): number of latently infected T-cells
E(t): number of actively infected T-cells
V(t): amount of virus

Parameters
$$\Gamma$$: rate of production of susceptible T-cells
$$\tau$$: fraction of T-cells susceptible to attack by HIV
$$\mu$$: removal rate of T-cells
$$\beta$$: rate of T-cell infection
p: fraction of infected T-cells that are latently infected
$$\alpha$$: rate that latent T-cells become activated
$$\delta$$: death rate/removal of actively infected T-cells
$$\pi$$: rate that virus is produced by actively infected T-cells
$$\sigma$$: rate of virus removal System of Equations 1
$$\frac{dR}{dt} = \Gamma \tau - \mu R - \beta VR $$
$$\frac{dL}{dt} = p \beta VR-\mu L - \alpha L$$
$$\frac{dE}{dt} = (1-p)\beta V R+ \alpha L - \delta E - \pi E$$
$$\frac{dV}{dt} = \pi E - \sigma V - \beta V R$$

System of Equations 2
$$\frac{dR}{dt} = \Gamma \tau - \mu R - \beta VR $$
$$\frac{dL}{dt} = p \beta VR-\mu L - \alpha L$$
$$\frac{dE}{dt} = (1-p)\beta V R+ \alpha L - \delta E $$
$$\frac{dV}{dt} = \pi E - \sigma V $$

The Attempt at a Solution


So clearly there is a difference between the number of infected T cells in system of equations 1 and
assigment2.png
2. System of equations 1 includes the term $$\pi E$$ while system of equations 2 does not in equation 3. Why is this?

There is a difference between the amount of virus in system of equations 1 and 2. System 1 includes the loss of term $$\beta VR$$ while the system of equations of 2 in equation 4. Why is this?
 

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upload_2018-1-30_17-51-54.png


So set 1 comes from the above picture in Otto (A Biologist's Guide to Mathematical Modeling in Ecology and Evolution) and set 2 comes from Science.

Apparently, both the article in Science and Otto missed the ##-\beta RV## in ##V(t)## but not in ##R(t)##, but you did not. [edit] However, at the bottom in Box 2.4 (continued) they claim it is negligible.

The ##-\pi E## term does not appear in ##dE\over dt## because the infected cell produces the virus particles but stays intact. This is explained in Box 2.4 (continued). So there I side with the Science/Otto sets.

You can check your set of equations by adding them all up. That should yield the in- and outgoing solid arrows plus the ##\pi E## as mentioned.

[edit] my advice: take your time to read the whole thing :smile:
 

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BvU said:
View attachment 219387

So set 1 comes from the above picture in Otto (A Biologist's Guide to Mathematical Modeling in Ecology and Evolution) and set 2 comes from Science.

Apparently, both the article in Science and Otto missed the ##-\beta RV## in ##V(t)## but not in ##R(t)##, but you did not. [edit] However, at the bottom in Box 2.4 (continued) they claim it is negligible.

The ##-\pi E## term does not appear in ##dE\over dt## because the infected cell produces the virus particles but stays intact. This is explained in Box 2.4 (continued). So there I side with the Science/Otto sets.

You can check your set of equations by adding them all up. That should yield the in- and outgoing solid arrows plus the ##\pi E## as mentioned.

[edit] my advice: take your time to read the whole thing :smile:

so is my equation for ##dE\over dt## correct for the figure? and what about the last equation ##dV\over dt## why is this different?
 
BvU said:
View attachment 219387

So set 1 comes from the above picture in Otto (A Biologist's Guide to Mathematical Modeling in Ecology and Evolution) and set 2 comes from Science.

Apparently, both the article in Science and Otto missed the ##-\beta RV## in ##V(t)## but not in ##R(t)##, but you did not. [edit] However, at the bottom in Box 2.4 (continued) they claim it is negligible.

The ##-\pi E## term does not appear in ##dE\over dt## because the infected cell produces the virus particles but stays intact. This is explained in Box 2.4 (continued). So there I side with the Science/Otto sets.

You can check your set of equations by adding them all up. That should yield the in- and outgoing solid arrows plus the ##\pi E## as mentioned.

[edit] my advice: take your time to read the whole thing :smile:

I was asked to compare the equations I have made to the equations given to find difference so I guess I was right? there should be some difference?
 
J6204 said:
so is my equation for dEdtdEdtdE\over dt correct for the figure?
No. E does not change when a virus is released.
J6204 said:
I was asked to compare the equations I have made to the equations given to find difference so I guess I was right? there should be some difference?
Was answered in an edit:
BvU said:
Apparently, both the article in Science and Otto missed the ##-\beta RV## in ##V(t)## but not in ##R(t)##, but you did not. [edit] However, at the bottom in Box 2.4 (continued) they claim it is negligible.

BvU said:
[edit] my advice: take your time to read the whole thing :smile:
 

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