Joint 3-D Reconstruction from Cryo Electron Microscopy and Solution X-ray Scattering Data

这项研究的目的是开发联合分析低温电子显微镜(EM)和溶液X射线散射数据的新方法，以确定球形病毒的三维结构。这一领域的研究是及时的，因为改进的显微镜和低温EM技术正在增加图像流量，而同步加速器和相关的低角度散射光束线允许测量质量更高的解决方案X射线散射数据。联合使用这两种类型的数据是一种自然的方法，因为它们可以弥补各自的优势和劣势。例如，低温电磁图像依赖于未知的取向参数，而溶液X射线散射数据不依赖于此。这项工作贯穿了两个主要主题：一个新的粒子散射密度模型，以及一个将该模型与所有实验数据相结合以重建粒子的统一方法。该模型的目的是精确而简明地描述粒子。特别是，所提出的模型强制粒子的有限实空间范围，允许单个粒子存在多种类型的对称性，具有很少的参数，并且在实空间和倒易空间中数学上都很简单。

The objective of the research is the development of new methods for jointly analyzing cryoelectron microscopy (EM) and solution x-ray scattering data in order to determine the 3D structure of spherical viruses. Research in this area is timely because improved microscopes and cryo EM techniques are increasing the flow of images while synchrotrons and associated low-angle scattering beam lines allow the measurement of qualitatively superior solution x-ray scattering data. The joint use of both types of data is a natural approach because of compensating strengths and weaknesses. For instance, cryo EM images depend on unknown orientation parameters while solution x-ray scattering data does not. There are two major themes that extend through the work: a new model for the scattering density of the particle and a unified way of combining the model with all of the experimental data in order to reconstruct the particle. The purpose of the model is to precisely and concisely describe the particle. In particular, the proposed model enforces the finite real-space extent of the particle, allows more than one type of symmetry to exist with an individual particle, has few parameters, and is mathematically simple in both real and reciprocal space.