Re: modeling the circadian baseline

Hi, Nick, It works and significantly decreased the objective function value, which is consistent with the results from Hempel et al. Thank you very much! Kind Regards, Ying Nick Holford wrote: > Ying, > > If you assign the ETA to a variable outside $DES then you can use the variable > in $DES e.g. > > $PK > > ETAT=ETA() ; ETA for random effect on offset in cycle > > $DES > > DPS2 = (KOUT*A1 + B1*DPI/12)*DCOS(DPI*(T+ETAT)/12) > > I would also suggest putting DPI = 3.14159 in $PK. There is no need to do this > assignment every time the differential equation solver is called. > > Nick > > Ying HONG wrote: > > > Dear NM users, > > > > A biomarker, which shows clear circadian rhythm during placebo > > treatment, was described by a turnover model with the introduction of a > > periodic time-dependent production function KST with two harmonics. The > > code in $DES is written as follows: > > > > $DES > > > > DPI = 3.14159 > > DPS1 = KOUT*A0 > > DPS2 = (KOUT*A1 + B1*DPI/12)*DCOS(DPI*T/12) > > DPS3 = (KOUT*B1 - A1*DPI/12)*DSIN(DPI*T/12) > > DPS4 = (KOUT*A2 + B2*DPI/6) *DCOS(DPI*T/6) > > DPS5 = (KOUT*B2 - A2*DPI/6) *DSIN(DPI*T/6) > > > > KST = DPS1 + DPS2 + DPS3 + DPS4 + DPS5 > > > > DADT(1) = KST - KOUT*A(1) > > > > In the paper published by Hempel et al (CPT, 1998;64:622-35), a ETA was > > introduced in the time T which accounts for the differences in wake-up > > times between subjects (e.g. DCOS(DPI*(T+ETA)/12). Because ETA is > > prohibited in the $DES, how can I code the interindividual variability > > of time in the control stream? > > > > Any suggestion is highly appreciated! > > > > Kind Regards, Ying > > > > -- > > Ying HONG, PhD > > Department of Pharmaceutical Sciences > > University at Buffalo, SUNY > > C237 Cooke Hall, Buffalo, NY 14260 > > > > Tel: 716 645 2828 ext 275 > > Fax: 716 645 3693 > > E-mail: [EMAIL PROTECTED] > > -- > Nick Holford, Dept Pharmacology & Clinical Pharmacology > University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand > email:[EMAIL PROTECTED] tel:+64(9)373-7599x86730 fax:373-7556 > http://www.health.auckland.ac.nz/pharmacology/staff/nholford/ -- Ying HONG, PhD Department of Pharmaceutical Sciences University at Buffalo, SUNY C237 Cooke Hall, Buffalo, NY 14260 Tel: 716 645 2828 ext 275 Fax: 716 645 3693 E-mail: [EMAIL PROTECTED]