Collaborative Research: Hydrodynamic Theories of the Dynamics, Fluctuations, Boundaries, and Shapes of Flocks

这一提议将发展“群集”理论：大量生物体或生物分子的集体、连贯运动。这种无所不在的生物现象发生在生物体（鸟群、鱼群）、细胞（游动细菌的集合、肿瘤中癌细胞的迁移）和亚细胞分子（长分子，如参与细胞运作和繁殖的微管和肌动蛋白丝）中。该项目将把最初为流体动力学（飞机机翼上的空气流动、天气预报和管道）开发的想法应用于羊群。这个项目将把这种方法扩展到研究是什么让鸟群在它们的边界上聚集在一起；研究有机体或分子的生与死的影响（这对活细胞内的分子非常重要，因为它们在运动中不断地产生和破坏），并将理论的预测与不同生物系统的实验进行比较。其中包括有丝分裂纺锤体的实验，这是一种纺锤形的长而坚硬的分子结构，称为微管，在细胞分裂时在细胞内部形成，它的作用是将染色体分离成两个子细胞。这项工作还将涉及生物群（如鸟类和鱼类），以研究它们的形状以及这些形状如何随着群体的移动而波动。这项工作是跨学科的，将推进凝聚态物理学、分子生物物理学、细胞生物学、流体力学、有机生物学和医学（通过对影响癌细胞迁移和伤口愈合的过程的更深层次的理解）。拟议的工作将通过让学生和博士后参与研究，以及在科罗拉多大学博尔德分校和俄勒冈大学开发新的课程材料，将研究和学习结合起来。

This proposal will develop the theory of "flocking": the collective, coherent motion of large numbers of organisms or biomolecules. This ubiquitous biological phenomenon occurs for organisms (flocks of birds, schools of fish), cells (collections of swimming bacteria, migration of cancer cells in tumors) and subcellular molecules (long molecules such as microtubules and actin filaments involved in the operation and reproduction of cells). The project will apply ideas originally developed for fluid dynamics (air flow over airplane wings, weather forecasting, and plumbing) to flocks.This project will extend that approach to investigating what holds flocks together at their boundaries; to study the effects of birth and death of organisms or molecules (which is very important for molecules inside living cells, which are constantly created and destroyed as they move), and to compare predictions of the theory with experiments on diverse biological systems. Among these are experiments on the mitotic spindle, a spindle-shaped structure of long, rigid molecules called microtubules that forms inside cells when they divide, and which acts to separate the chromosomes into the two daughter cells. This work will also address flocks of organisms (such as birds and fish) to study their shapes and how those shapes fluctuate as the flock moves.This work is strongly interdisciplinary and will advance condensed-matter physics, molecular biophysics, cellular biology, fluid mechanics, organismal biology, and medicine (through a deeper understanding of processes that impact cancer cell migration and wound healing). The proposed work will integrate research and learning by involving students and postdoctoral fellows in the research, and through the development of new course materials at CU-Boulder and the University of Oregon.