Sentence:  Essentially these birefringence studies show that at low rates of shear a tension is present at 45 ` to the <WSD>direction</WSD> of shear , and as the rate of shear increases , the direction of the maximum tension moves asymptotically toward the direction of shear . 
Meaning of the word marked with <WSD> tags:  the spatial relation between something and the course along which it points or moves