Development of evaluation method for bacterial motility based on the flow dynamics and the large deviation mechanics

布朗运动是纳/微尺度流体动力学的基本现象。另一方面，已知细菌运动显示出一定的随机性，而本质上不同于布朗运动。近年来，由于单粒子跟踪（SPT）或单分子跟踪（SMT）技术在医学和生物学应用以及材料加工中的重要性，该技术得到了迅速的发展。然而，与测量技术相比，对所获得的轨迹数据的分析尚未得到集中解决。在这项研究中，我们开发了基于大偏差原则的评价方法。特别是，我们已经表明，它是可能的，以阐明扩散各向异性的长轴粒子的粒子取向的信息。此外，我们已经表明，有限样本效应可以是有用的细菌运动的表征。

Brownian motion is a fundamental phenomenon of nano/micro scale fluid dynamics. On the other hand, bacterial motility is known to show some stochasticity while essentially different from Brownian motion. Recently, there have been drastic developments in the techniques of single particle tracking (SPT) or single molecule tracking (SMT) due to the importance in the medical and biological applications as well as material processing. However, the analysis of the obtained trajectory data has not been addressed intensively compared to the measurement technology. In this study, we have developed the evaluation methodology based on the large deviation principle. In particular, we have shown that it is possible to elucidate the diffusion anisotropy of a prolate particle without the information of particle orientation. Furthermore, we have shown that the finite-sample effect can be useful in the characterization of bacterial motility.