Hi AFNI experts,

I had few questions about the [afni.nimh.nih.gov] script and generating IRF.
set dur = 15 # use a 15-second curve for BLOCK
set nt_irf = `ccalc -i "$dur/$TRup"`

set hrf_file = x.BLOCK.1D
3dDeconvolve -nodata $nt_irf 0.1 -polort -1 \
-num_stimts 1 \
-stim_times 1 1D:0 "BLOCK(0.1,1)" \
-x1D $hrf_file -x1D_stop

1. Should the 0.1 within the -nodata option and the BLOCK() function be the same as $TRup? Currently, my TRup is 0.5 and without changing those options (using 0.1 for both), it creates the same IRF when using TRup of 0.1 but with 30 time points instead of 150.
2. If so, should the change of 0.1 to $TRup apply to both the -nodata option and BLOCK() function or only the -nodata option. Using a TRup of 0.5, each option provides a slightly different IRF that looks similar to when using a TRup of 0.1 but with only 30 time points instead of 150.

3. Also, is time being controlled for twice for the physiological variable? Once when the physiological seed time series is detrended and also again during the polort option of 3dDeconvolve?

Thanks!,
Ekarin