% In this code we include logistic growth of normal cells and PM cells

% along with radiation effect from Gibins work.

function xprime = sys_ndRadNordic(t,x,D)

xprime = zeros(2,1);

% Parameters that are fixed

N = 10^9; % Sachs

lambda = 0.40; %Sachs

r = 0.85; 

K = 20;        

d = D/K;       

tau = 0.02;   % radiation time- 30 minutes = 0.02 days

alpha = 0.25; % Damien Weber et al. 

gamma = 10^(-9); % (d/tau) is the dose rate

    if(t<=K+tau)

        t-floor(t);

        if (t-floor(t)<=tau)

            t;

            xprime(1) = lambda*x(1)*(1-x(1)) - alpha*(d/tau)*x(1) - gamma*(d/tau)*x(1);

            xprime(2) = r*lambda*x(2)*(1-x(1)) - alpha*(d/tau)*x(2) + gamma*(d/tau)*N*x(1);

        else

            xprime(1) = lambda*x(1)*(1-x(1));

            xprime(2) = r*lambda*x(2)*(1-x(1));

        end

    else

        xprime(1) = lambda*x(1)*(1-x(1));

        xprime(2) = r*lambda*x(2)*(1-x(1));

    end