Theoretical Problems in Soft Matter and Quantitative Biology

软物质和定量生物学的理论问题

• 批准号: 1306367
• 负责人: David Nelson
• 金额: $ 40.5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-15 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1306367&HistoricalAwards=false
• 关键词: Theoretical; Problems; Soft; Matter; Quantitative

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.

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将研究位错介导的伸长和弯曲的杆状细菌细胞壁，以及相关现象的胶体颗粒组件吸附在圆柱体上。就细菌而言，显着的聚糖链延伸机制为系统性错位攀爬提供动力，从而产生传统材料科学中很少有类似物的生长动力学。位错轨迹应受到长程弹性相互作用和外部应力以及通过Peach-Kohler力的膨压的影响。对于固体圆柱体上的胶体来说，滑动动力学占主导地位。由于孤立的位错与伯格斯矢量沿着圆柱轴表现得像紧凑的晶界，通过滑移分离可能能够调解不同叶序颗粒packings.In另一个推力之间的过渡，PI将使用非平衡统计动力学，群体遗传学和概率论的工具，以解决有关的迁移，竞争和合作的问题。这些现象在许多物种的历史中发挥了至关重要的作用，在固体表面上，如入侵物种的迁移，或动物组织的细菌入侵，以及在液体环境中，如海洋，其中光合生物如蓝藻和浮游植物在流体平流的存在下竞争。考虑到范围的扩大，PI将研究微生物之间的互利竞争如何在二维和三维的固体环境中发挥作用，特别强调与膨胀动力学相结合的前沿波动的影响。由于地球的大部分进化历史都发生在河流、湖泊和海洋中，PI还将研究离散生物的固定时间和概率，这些生物在平流流体流动（包括高雷诺数湍流）下繁殖和竞争。特别有趣的现象出现的微生物的倍增时间是在中间的一个柯尔莫哥洛夫式级联的涡流周转时间。该项目提供了一个不寻常的跨学科环境，教育和培养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，使理论承担，部分问题，有关的环境，可持续性，和生物启发的材料。非技术性总结该奖项支持理论研究和教育在材料科学，统计物理学和生物物理学之间的接口。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，植物通常依赖真菌来获得重要的营养。甚至人类社会也是个人之间合作的产物。尽管互利主义具有明显的优势和普遍性，但它的存在往往很难解释：合作可能屈服于欺骗和随机的数字波动。 关于固体表面上的微生物和海洋等动态环境中的微生物如何竞争和合作的详细理论将有助于更好地了解我们星球的生态和生物物质，并对受生物有机体启发的先进材料产生影响。这项研究对于进一步了解细胞壁如何赋予生长中的微生物形状和强度也很重要。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的薄网组成。该项目提供了一个不同寻常的跨学科环境，以教育和培养学生现代凝聚态理论、材料理论、统计物理学和生物物理学，使理论部分地承担与环境、可持续性和生物启发材料相关的问题。