Theoretical Problems in Soft Matter and Quantitative Biology

该奖项支持材料科学、统计物理学和生物物理学之间的理论研究和教育。PI将研究位错介导的杆状细菌细胞壁的延伸和弯曲，以及在圆柱体上吸附的胶体颗粒组件中的相关现象。以细菌为例，非凡的聚糖链延伸机制为系统的位错攀登提供了动力，导致了传统材料科学中很少有类似物的生长动力学。位错轨迹应受到远程弹性相互作用以及外部应力和通过Peach-Kohler力的膨胀压力的影响。对于固体圆柱体上的胶体，滑动动力学起主导作用。由于沿圆柱体轴的Burgers矢量的孤立位错表现得像致密的晶界，通过滑动分离可能能够调节不同层状粒子填料之间的转变。在另一个方面，PI将使用非平衡统计动力学、人口遗传学和概率论的工具来处理与移徙、竞争和合作有关的问题。这些现象在许多物种的历史上都发挥了至关重要的作用，无论是在固体表面，如入侵物种的迁移，还是细菌对动物组织的入侵，还是在液体环境，如海洋，蓝藻和浮游植物等光合生物在流体平流的存在下竞争。考虑到范围扩展，PI将研究微生物之间的互惠竞争如何在二维和三维固体环境中发挥作用，特别强调锋面波动与膨胀动力学相结合的影响。由于地球的大部分进化史都发生在河流、湖泊和海洋中，因此PI还将研究受平流流体（包括高雷诺数湍流）影响而繁殖和竞争的离散生物的固定时间和概率。特别有趣的现象出现在微生物的倍增时间是在柯尔莫哥洛夫级联的漩涡周转时间的中间。该项目提供了一个不同寻常的跨学科环境来教育和训练学生在现代凝聚态理论、材料理论、统计物理学和生物物理学方面的知识，将理论部分地应用于与环境、可持续性和生物启发材料相关的问题。该奖项支持材料科学、统计物理学和生物物理学之间的理论研究和教育。微生物之间的合作是许多复杂系统的核心。例如，肠道细菌可以帮助动物宿主消化纤维素。在生态系统层面上，植物通常依靠真菌来获取重要的营养。甚至人类社会也是个体之间合作的产物。尽管互惠主义具有明显的优势和普遍性，但它的存在往往难以解释：合作可能屈服于欺骗和随机数字波动。关于固体表面和海洋等动态环境中微生物如何竞争和合作的详细理论，将有助于更好地理解我们的星球和生物物质的生态学，并对受生物有机体启发的先进材料产生影响。这项研究对于促进对细胞壁如何赋予生长中的微生物形状和强度的理解也很重要。特别令人感兴趣的是革兰氏阴性细菌，其细胞壁由大链状分子组成的软链组成的薄网。对生长机制的进一步了解可能导致更有效的抗生素，并更好地补救人类和动物疾病。该项目提供了一个不同寻常的跨学科环境来教育和训练学生在现代凝聚态理论、材料理论、统计物理学和生物物理学方面的知识，将理论部分地应用于与环境、可持续性和生物启发材料相关的问题。

TECHNICAL SUMMARYThis award supports theoretical research and education at the interface between materials science, statistical physics and biophysics. The PI will study dislocation-mediated elongation and bending of rod-shaped bacterial cell walls, and related phenomena in colloidal particle assemblies adsorbed on cylinders. In the case of bacteria, remarkable glycan strand extension machinery powers systematic dislocation climb, leading to growth dynamics with few analogs in conventional materials science. Dislocation trajectories should be influenced by long-range elastic interactions and by external stresses and turgor pressure via the Peach-Kohler force. Glide dynamics dominates for colloids on solid cylinders. Because isolated dislocations with Burgers vectors along the cylinder axis behave like compact grain boundaries, separation via glide may be able to mediate transitions between different phyllotactic particle packings.In another thrust, the PI will use the tools of non-equilibrium statistical dynamics, population genetics and probability theory to address issues related to migrations, competition and cooperation. These phenomena have played a crucial role in the history of many species, on both solid surfaces, as in migrations of invasive species, or bacterial invasions of animal tissue, and in liquid environments such as the ocean, where photosynthetic organisms such as cyanobacteria and phytoplankton compete in the presence of fluid advection. With range expansions in mind, the PI will study how mutualistic competitions between microorganisms play out in solid environments in two and three dimensions, with a particular emphasis on the effect of front undulations combined with inflationary dynamics. Because much of earth's evolutionary history took place in rivers, lakes and oceans, the PI will also study fixation times and probabilities for discrete organisms that reproduce and compete subject to advecting fluid flows, including high Reynolds number turbulence. Especially interesting phenomena arise for microorganisms whose doubling times are in the middle of a Kolmogorov-like cascade of eddy turnover times. This project provides an unusual interdisciplinary environment to educate and train students in modern condensed matter theory, materials theory, statistical physics, and biological physics to bring theory to bear, in part, on problems related to the environment, sustainability, and biologically inspired materials.NONTECHNICAL SUMMARYThis award supports theoretical research and education at the interface between materials science, statistical physics and biophysics. Cooperation among microorganisms is at the heart of many complex systems. For example, gut bacteria can help animal hosts digest cellulose. On an ecosystem level, plants often rely on fungi to receive important nutrients. Even human societies are products of cooperation between individuals. Despite the apparent advantage and pervasiveness of mutualism, its existence is often difficult to explain: Cooperation can succumb to cheating and to stochastic number fluctuations. A detailed theory of how microorganisms on solid surfaces and in dynamic environments such as the ocean compete and cooperate will lead to a better understanding of the ecology of our planet and living matter with implications for advanced materials inspired by biological organisms. This research is also important to advance understanding of how cell walls endow growing microorganisms with a shape and strength. Of particular interest are gram-negative bacteria, whose cell walls consist of a thin meshwork of soft strands composed of large chain-like molecules. An improved understanding of growth mechanisms could lead to more efficient antibiotics, and better remediation of human and animal diseases.This project provides an unusual interdisciplinary environment to educate and train students in modern condensed matter theory, materials theory, statistical physics, and biological physics to bring theory to bear, in part, on problems related to the environment, sustainability, and biologically inspired materials.