Self-organization of dense active matter

技术总结分子和细胞生物科学部和材料研究部为该奖项提供资金。它支持活性物质的理论研究和教育。活性物质是由许多相互作用的自驱动单元、活性粒子组成的，它们各自消耗能量，共同产生运动或机械应力。实现的范围从细菌群到上皮细胞克隆，再到人造胶体游泳者的悬浮。PI将以她在软物质和非平衡统计物理领域的专业知识和往绩为基础，研究三类系统：*细菌悬浮液作为模型活动系统，可以在流体和类固体相中自组织，以及丰富多样的涌现模式。以细菌悬浮液为原型系统，PI将对活性物质的自持动力学相进行分类，并阐明它们的性质。*自推进胶体--由自催化反应推动的胶体颗粒组成的生命系统的巧妙合成类似物已经被设计出来。这些系统为活性物质理论提供了理想的定量测试基础。*细胞集落和组织，目的是了解细胞-细胞和细胞-细胞外基质相互作用在控制力的产生和传递、集体迁移以及活组织材料特性的出现方面的相互作用。该项目将在几个领域产生广泛的、潜在的变革性影响，从物理到生物学，以及生物医学、化学和组织工程。与实验小组的合作将为这一快速增长的领域中直接感兴趣和相关的现象提供理论研究的重点。该奖项支持的研究将包括本科生、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，打开广泛的就业机会。非技术总结分子和细胞生物科学部以及材料研究部为该奖项提供资金。它支持活性物质的理论研究和教育。活性物质是指由许多相互作用的单元或粒子组成的一类非平衡系统，这些单元或粒子各自消耗能量，共同产生大范围的相干运动。一个例子是游泳细菌的悬浮液。每个单独的细菌都是一种活跃的颗粒，通过消耗营养物质来推动自己通过液体或其他介质。一群密集的细菌作为一种活的流体集体行为，可以以复杂的规则模式自组织，表现出湍急的运动，或者“冻结”成固体状的生物膜。这种“紧急行为”，即许多相互作用的实体的集合显示出具有新的宏观性质的状态下的大规模空间或时间组织，当然也发生在无生命物质中(例如，当一个人降低温度时，从水到冰的转变)，但在活动系统中获得了一种新的未被探索的丰富性，这些系统不是由外部旋钮(温度)调节的，而是由每个单位内部产生的能量调节的。活性系统跨越了从活细胞的细胞骨架到细菌悬浮液、组织和生物体，再到鸟群、鱼群和昆虫群等动物群体的巨大长度范围。将分子尺度上注入的能量转化为宏观尺度上有组织的、复杂的运动和特定功能的能力是生命状态的一种独特的力学性质。该奖项支持的研究旨在通过回答几个问题来理解和利用这一决定性性质：生命物质的行为中是否存在可以用凝聚态物理学的工具和思想来描述的“普遍”性质，例如将密集的细菌群“冻结”成固体状生物膜或融合细胞层的玻璃动力学？生命系统的一些决定性属性，如能动性或适应外界刺激的能力，能否在合成结构中复制？组织的机械特性等新出现的行为是如何产生于单个细胞的？该项目将在多个领域产生广泛的、潜在的变革性影响，从物理到生物学，以及生物医学、化学和组织工程，并在几个方面造福社会。例如，了解细胞在伤口愈合和生物膜形成过程中的集体行为将有助于表征单个细胞的改变和突变如何影响集体机械性能并可能导致病理。该奖项支持的研究将包括本科生、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，打开广泛的就业机会。

TECHNICAL SUMMARYThe Division of Molecular and Cellular Biosciences and the Division of Materials Research contribute funds to this award. It supports theoretical research and education in active matter. Active matter is composed of many interacting self-driven units, active particles, that individually consume energy and collectively generate motion or mechanical stress. Realizations range from bacterial swarms to epithelial cell colonies to suspensions of artificial colloidal swimmers. The PI will build on her expertise and track record at the interface of soft matter and nonequilibrium statistical physics to investigate three classes of systems:* Bacterial suspensions as model active systems that can self-organize in fluid and solid-like phases, as well as a rich variety of emergent patterns. Using bacterial suspension as prototype systems, the PI will classify the self-sustained dynamical phases of active matter and elucidate their properties. * Self-propelled colloids - Ingenious synthetic analogues of living systems have been engineered that consist of colloidal particles propelled by self-catalytic reactions. These systems provide an ideal quantitative testing ground for active matter theories.* Cell colonies and tissues, with the goal to understand the interplay of cell-cell and cell-extracellular matrix interactions in controlling force generation and transmission, collective migration, and the emergence of the materials properties of living tissues. This project will have a broad, potentially transformative impact across several fields, from physics to biology and biomedical, chemical and tissue engineering. The collaboration with experimental groups will provide focus to the theoretical research on phenomena of direct interest and relevance in this rapidly growing field. The research supported by this award 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 broad spectrum of employment opportunities.NONTECHNICAL SUMMARYThe Division of Molecular and Cellular Biosciences and the Division of Materials Research contribute funds to this award. It supports theoretical research and education in active matter. The name "active matter" refers to a class of nonequilibrium systems composed of many interacting units or particles that individually consume energy and collectively generate coherent motion at large scales. An example is a suspension of swimming bacteria. Each individual bacterium is an active particle that propels itself through a fluid or other medium by consuming nutrients. A dense swarm of bacteria behaves collectively as a living fluid and can self-organize in complex regular patterns, exhibit turbulent motion, or "freeze" into a solid-like biofilm. This type of "emergent behavior", where a collection of many interacting entities shows large-scale spatial or temporal organization in a state with novel macroscopic properties, occurs of course also in inanimate matter (for instance, the transition from water to ice as one lowers the temperature), but acquires a new unexplored richness in active systems that are tuned not by an external knob (the temperature), but by energy generated internally by each unit. Active systems span an enormous range of length scales, from the cytoskeleton of living cells, to bacterial suspensions, tissues and organisms, to animal groups such as bird flocks, fish schools and insect swarms. The ability to turn energy injected at the molecular scale into organized and complex motion and specific functions at the macroscopic scale is a unique mechanical property of the living state. The research supported by this award aims at understanding and harnessing this defining property by answering several questions: Are there "universal" properties in the behavior of living matter, such as the "freezing" of a dense bacterial swarm into a solid-like biofilm or the glassy dynamics of confluent cell layers, that can be described using the tools and ideas of condensed matter physics? Can some of the defining properties of living systems, such as motility or the ability to adapt their response to external stimuli, be reproduced in synthetic constructs? How does the emergent behavior of tissues, such as their mechanical properties, arise from that of individual cells?The project will have a broad, potentially transformative impact across several fields, from physics to biology and biomedical, chemical and tissue engineering, and benefit society in several ways. For instance, understanding collective behavior of cells during wound healing and biofilm formation will aid in the characterization of how alterations and mutations in individual cells affect collective mechanical properties and may lead to pathologies. The research supported by this award 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 broad spectrum of employment opportunities.