function [ dQ ] = photobleach( ~,Q )
%PHOTOBLEACH Model of a cell being photobleached (at room temperature)
%            with 1W of light.
%   Notes:
%   --Since light is so powerful, we make the assumption that mature KR
%     is always in the excited state. Thus, S is always zero.
%   --Very low polymerase, activity (2 orders of magnitude less) 
%     since cells are not growing (but some since IPTG is sill there)
%   --Very low protein synthesis rate (2 orders of magnitude less)
%   --Lower protein degradation rate since proteases work optimally at
%     37deg (one order of magnitude decrease)


%SPECIES
mRNA = Q(1);        %mRNA transcript
immature = Q(2);    %KR without mature chromophore
%KR_S = 0;           %KR with mature chromophore (singlet state)
KR_S_ex = Q(4);     %KR in singlet excited state (S*)
KR_T_ex = Q(5);     %KR in triplet excited state (T*)
KR_deac = Q(6);     %KR deactivated (photobleached)
SOx = Q(7);         %Superoxide

%Basic parameters
N_a = 6.022e23;
Vcell = 6.7e-16;                %cytoplasmic volume in liters
copyNo = 5e1;

%SOD kinetics
SOD_conc = 1e3 / (N_a*Vcell);   %est. 1000 molecules/cell
SOD_Kcat = 1667;                %turnover rate
SOD_Km = 2e-6;
SOD_Vmax = SOD_Kcat*SOD_conc;   %maximum rate

%CONSTANTS  for reaction rates
k_RNAsynth = 0.00347/(N_a*Vcell);%mRNA synthesis: 0 -> mRNA
k_RNAdeg = 0.0039;              %mRNA degradation: mRNA -> 0
k_KRsynth = .000032;            %KR synthesis: mRNA -> mRNA + immature
k_KRmature = 4.81e-5;           %KR chrom. maturation: immature -> KR_S(*)
k_KRdeg1 = 7.7e-7;              %KR immature degradation: immature -> 0
k_KRdeg3 = 7.7e-7;              %KR mature degradation: S* -> 0
k_KRdeg4 = 7.7e-7;              %KR mature degradation: T* -> 0
k_KRisc = 6.6e6;                %intersys. crossing: S* -> T*
k_KRrd = 50;                    %radiationless deactivation: T* -> S*
k_KRsox1 = 99*1e-4/.15; %superoxide production: T* + 2H2O -> S* + SOx
k_KRsox2 = 1e-4/.15; %superoxide production: T* + 2H2O -> Deac + SOx


%REACTIONS
RNAsynth = k_RNAsynth*copyNo;       %mRNA synthesis treated as zero order
RNAdeg = mRNA*k_RNAdeg;
KRsynth = mRNA*k_KRsynth;
KRmature = immature*k_KRmature;
KRdeg1 = immature*k_KRdeg1;
KRdeg3 = KR_S_ex*k_KRdeg3;
KRdeg4 = KR_T_ex*k_KRdeg4;
KRisc = KR_S_ex*k_KRisc;
KRrd = KR_T_ex*k_KRrd;
KRsox1 = KR_T_ex*k_KRsox1;
KRsox2 = KR_T_ex*k_KRsox2;

dQ = zeros(7,1);

dQ(1) = RNAsynth - (RNAdeg);
dQ(2) = KRsynth - (KRmature + KRdeg1);
dQ(3) = 0;
dQ(4) = KRmature + KRrd + KRsox1 -(KRisc + KRdeg3);
dQ(5) = KRisc - (KRrd + KRsox1 + KRsox2 + KRdeg4);
dQ(6) = KRsox2;
dQ(7) = KRsox1 + KRsox2 - .001*SOD_Vmax*SOx/(SOD_Km+SOx);
end