These were then divided by a flat-field image, which was generated by collecting several hundred frames of data at the same wavelength, at a slower frame rate, in which the subject was instructed to move fixation erratically.
Additional file 2 shows the same sequence but with the patient's IVF superimposed and moving with fixation; the less transparent areas equate to defects in the IVF.
Only in one case was the device moving after fixation to the skin and in one case it had been secured additionally by a single stitch.
The patient gazed at the fixation point of the device, at the center of their visual field, and the investigator was then able to control the eye's position by moving the fixation point.
Nevertheless, alternative selection models are possible – for example, the alleles may not be neutral in events between famines which may provide a counterbalancing selective pressure preventing the genes moving to fixation.
Pursuit was controlled by moving the fixation task within a third of width and height of the screen with an unequal number of cycles of sinusoidal displacement per trial in horizontal and vertical axes, respectively (randomly assigned 3 or 4 cycles, each with random initial phases).
Many attention competition tasks that have shown disengagement difficulties use repeated and predictably moving central fixations (e.g. a spinning animation), which may be particularly "engaging" for individuals with autism.
To start a trial, while the participant was looking at the central fixation point, they pressed a button which moved the fixation point 13.65° to right of center.
One might imagine, therefore, that if mutations affecting fat deposition had occurred at random over the past 4 million years, some of these older mutations might have moved to fixation, but that many mutations would still be under the process of selection and their fixation would be incomplete.
This is also completely coherent since, in this situation, allelic frequencies have moved towards fixation.
