3-D understanding of electron microscopy images of nano bio objects by computing generative mechanical models

Cryo electron microscopy records essentially projection images of each of many instances of a nano bio object. This data allows reconstruction of a stochastic model of the object, i.e., the mean and covariance functions of the electron scattering intensity of the object. Understanding the covariance function, which characterizes the heterogeneity of the instances of the object, is challenging because the covariance function is not wide-sense stationary but instead depends separately on the two three-dimensional positions. This paper describes a method, qualitatively motivated by fluctuation-dissipation theory, for estimating a spring-and-mass mechanical model of the object. Then, from the model, a wide range of properties of the object can be understood, such as normal modes of vibration.