Effects of human FLT3 ligand on myeloid leukemia cell growth: heterogeneity in response and synergy

This invention relates to a dynamic photoelasticimeter with a rotating birefringent element. It comprises a laser, a birefringent plate rotatable at a constant speed, a model to be studied, a circular analyzer and a photodetector supplying signals at its output having frequency components of 2 omega and 4 omega . The ratio of the amplitudes of these signals supplies an indication of the phase shift phi (t) contributed by the model, and the phase of the signal of the frequency 4 omega contributes information as to the orientation theta of the axes of the model at the point in question. The present invention provides a particularly simple and accurate dynamic photoelasticimeter.