A sample of an oriented semi-crystalline polymer is subjected to uniaxial tensile stress, \( \sigma \), in an X-ray diffractometer. The wavelength of X-ray radiation (Cu K\( \alpha \)) is \( \lambda = 1.542 \, \text{Å} \). The position of the (002) peak, which was found initially at a Bragg angle of 37.50° at \( \sigma = 0 \, \text{MPa} \), shifted to 37.45° at \( \sigma = 160 \, \text{MPa} \). Assuming elastic deformation, the strain (rounded off to three decimal places) in the sample along the direction of applied stress is \(\underline{\hspace{2cm}}\) \( \times 10^{-3} \).