Dynamics and Mechanics of Active Matter

非技术总结该奖项支持活性物质的理论研究和教育，由自驱动实体组成，如鸟群或活细胞，这些实体从环境中获取能量以产生协调的运动。将分子尺度上注入的能量转化为宏观尺度上的有组织的运动和功能的能力是生命系统的一个决定性性质。然后，人们可能会认为，这样的组织必须由复杂的通信途径或生化信号控制。然而，近年来，研究人员已经设计出了许多具有生命特性的合成类似物，从由化学反应提供动力的微型游泳者到能够自组织行为的纳米机器人群，展示了物理互动在控制集体行为方面的关键作用。PI和她的团队的研究的中心目标是量化基于最小交互集的物理模型可以捕获生活系统和工程系统中的复杂组织的条件，并开发和测试此类模型。这项研究将为定量描述自然界中的新兴现象提供一个新的强大的数学框架，在自然界中，大群体表现出与个人非常不同的协调行为。PI将与锡拉丘兹大学和普林斯顿大学的实验者合作，使用活性物质范式来确定驱动土壤细菌黄色粘球菌生命周期的物理机制，该生命周期由集体和个人行为之间的连续反馈循环控制。PI和她的学生还将模拟合成微泳者的集体行为，并检查这些活跃粒子驱动惰性粒子组装和组织所需的条件。这项工作将为能够主动组装、重新配置和自我修复的智能材料的工程铺平道路。该项目将在从物理到生物再到工程的几个领域产生革命性影响，并在几个方面造福社会。例如，通过区分由物理机制而不是遗传学机制触发的转化，对黄花分枝杆菌的工作将有助于减少在常规遗传学研究中必须研究的大量可能性。这项研究将包括本科生、研究生和博士后研究人员的机会。它的高度跨学科性质将在科学和生物工程之间提供广泛的培训，打开各种就业机会。技术总结该奖项支持关于活性物质的理论研究和教育。这个名字指的是由许多相互作用的实体组成的扩展系统，这些实体被微观尺度上注入的能量驱使失去平衡，打破了详细的平衡。例子包括许多生命系统，从鸟群到活细胞，以及工程系统，从由马达蛋白激活的体外生物聚合物网络到合成微泳者。PI将使用多管齐下的方法，从基于代理人的模型到连续介质现象学，并通过与实验人员的合作来促进对活性物质的组织原则和力学的理解。所讨论的问题围绕三个目标组织：(1)使用最小模型来描述活性物质的非平衡统计力学，特别关注限制引起的空间不均匀行为；(2)通过研究拓扑缺陷的动力学和紧急行为来识别受限几何中活动流动的一般性质；以及(3)应用活性物质范式来阐明驱动黄色粘球菌复杂生命周期的物理机制。关于自推进粒子模型的工作将计算和理论相结合，以解决不具有微观时间反转对称性的活动系统的非平衡统计力学的基本问题。它将具体审查在多大程度上可能对均衡概念进行有效描述。拓扑缺陷在驱动和维持自我维持的活性流动中的作用的研究将为描述体内和体外从细胞质到细菌悬浮液的流动模式之间的转变提供一个强大的框架。通过对黄花假单胞菌的研究，PI将证明活动物质范式为组织生物数据和分离在控制生命系统复杂发展周期中发挥作用的物理机制提供了一种有用的方法。活性物质领域汇聚了来自广泛学科的社区，并影响到从生物学到材料设计等领域。拟议的自推进粒子模型和主动组装方面的工作将指导具有编程功能的新材料的开发。对微生物发育的研究旨在区分由物理机制而不是遗传学触发的转化，并将有助于减少在遗传学研究中必须研究的大量可能性。拟议的工作将为物理、工程和生物学领域的研究生和博士后提供广泛的培训，并促进多样化的STEM劳动力的发展。国际和平协会将继续与科学界接触，组织会议和学校，为年轻科学家提供职业发展机会。

NON-TECHNICAL SUMMARYThis award supports theoretical research and education in active matter, consisting of assemblies of self-driven entities, such as bird flocks or living cells, that take energy from the environment to produce coordinated motion. The ability to turn energy injected at the molecular scale into organized motion and function at the macroscopic scale is a defining property of living systems. One may then think that such organization must be controlled by complex communication pathways or biochemical signaling. In recent years researchers have, however, engineered a number of synthetic analogues with life-like properties, from microswimmers powered by chemical reactions to swarms of nanobots capable of self-organized behavior, demonstrating the key role of physical interactions in controlling collective behavior. The central goal of the research by the PI and her team is to quantify the conditions under which physical models based on a minimal set of interactions can capture complex organization in both living and engineered systems, and to develop and test such models. The research will provide a new powerful mathematical framework for describing quantitatively emergent phenomena in nature, where large groups exhibit coordinated behaviors that are very different from those of the individuals. Working with experimentalists at Syracuse University and at Princeton University, the PI will employ the active matter paradigm to identify the physical mechanisms that drive the life cycle of the soil-dwelling bacterium Myxococcus xanthus, which is controlled by a continuous feedback loop between collective and individual behavior. The PI and her students will also model the collective behavior of synthetic microswimmers and examine the conditions required for such active particles to drive the assembly and organization of inert particles. This work will pave the way to the engineering of smart materials capable of active-assembly, reconfiguration, and self-healing.The project will have transformative impact across several fields, from physics to biology to engineering, and benefit society in several ways. For instance, by differentiating transformations that are triggered by physical mechanisms as opposed to genetics, the work on M. xanthus will help cut down the vast number of possibilities that must be investigated in routine genetic studies. The research will include opportunities for undergraduates, graduate students and postdoctoral researchers. Its highly interdisciplinary nature will provide broad training at the interface between science and bioengineering, opening up a variety of employment opportunities.TECHNICAL SUMMARYThis award supports theoretical research and education on active matter. This name refers to extended systems composed of many interacting entities that are driven out of equilibrium by energy injected at the microscopic scale, breaking detailed balance. Examples include many living systems, from bird flocks to living cells, and engineered ones, from in vitro biopolymer networks activated by motor proteins to synthetic microswimmers. The PI will use a multipronged approach ranging from agent-based models to continuum phenomenology, and informed by collaborations with experimenters to advance understanding of the organizational principles and mechanics of active matter. The problems addressed are organized around three objectives: (1) using minimal models to formulate the nonequilibrium statistical mechanics of active matter, with specific attention to spatially inhomogeneous behavior induced by confinement; (2) identifying generic properties of active flows in confined geometry by examining the dynamics and emergent behavior of topological defects; and (3) applying the active matter paradigm to elucidate the physical mechanisms that drive the complex life cycle of Myxococcus xanthus. The work on self-propelled particle models combines computation and theory to address fundamental questions on the nonequilibrium statistical mechanics of active systems with no microscopic time reversal symmetry. It will specifically examine the extent to which effective descriptions in terms of equilibrium concepts may be possible. The study of the role of topological defects in driving and maintaining self-sustained active flows will provide a powerful framework for characterizing transitions between flow patterns in biofluids in vivo and in vitro, from the cytoplasm to bacterial suspensions. Through the work on M. xanthus, the PI will demonstrate that the active matter paradigm provides a useful way for organizing biological data and isolate the physical mechanisms at play in controlling complex developmental cycles of living systems. The field of active matter brings together communities from a broad range of disciplines and impacts areas ranging from biology to materials design. The proposed work on self-propelled particle models and active assembly will guide the development of new materials with programmed functions. The research on microbial development aims at differentiating transformations that are triggered by physical mechanisms as opposed to genetics and will help cut down the vast number of possibilities that must be investigated in genetic studies. The proposed work will provide broad training for graduate students and postdocs at the interface of physics, engineering and biology and promote the development of a diverse STEM workforce. The PI will continue her engagement with the scientific community by organizing conferences and school that will provide professional development opportunities for young scientists.