The details are provided in the supplementary material: http://science.sciencemag.org/content/sci/suppl/2017/10/25/science.aag2612.DC1/aag2612_George_SM.pdf htt

The details are provided in the supplementary material: http://science.sciencemag.org/content/sci/suppl/2017/10/25/science.aag2612.DC1/aag2612_George_SM.pdf http://science.sciencemag.org/content/sci/suppl/2017/10/25/s... (mentioned by boltzmannbrain in one of the other comments)