Active and Driven Soft Matter

该奖项支持软凝聚态物质和生物物理学的理论研究和教育，特别是在驱动和活性物质领域。“活性物质”这个名字最近被创造出来，指的是由许多相互作用的单元组成的软材料，这些单元单独消耗能量，共同产生运动或机械应力。例子包括细菌悬浮液、活细胞的细胞骨架、底物或软弹性基质上的细胞集合，甚至是单层的振动颗粒棒。这些系统表现出大规模的涌现行为，在有序和无序状态之间转换，模式形成，以及新的流变学和力学性质。利用凝聚态物质和统计物理的工具，理论上可以把它们描述为一种新的“活的”软材料。该项目的一个主要目标是将纯物理相互作用（如排除的体积效应或介质介导的流体动力耦合）与生物化学调节的遗传信号或外部对称性破坏效应（如趋化性）在控制生物体集合的紧急行为中的作用分开。这个重要的问题具有从对生物膜形成的理解到伤口愈合和组织形成的建模的影响。该奖项支持以下研究：(1)使用磁性和液晶系统的类比来模拟游泳微生物集合中的模式形成和群集，了解这些生命系统的流变学，并调查活体和无生命自推进单位集合之间的相似性；(2)模拟运动细胞在软基质或三维凝胶中的行为，目的是了解基质或基质弹性在控制细胞集体迁移、组织和分选中的作用，最终导致组织形成；(3)了解常规软物质（如胶状凝胶和玻璃）中的输运，这种输运是由外力（如电场）驱动而失去平衡的，并且其平动不变性被物质无序打破。我们将积极招募弱势群体和本科生参与本研究项目。该奖项支持软凝聚态物质和生物物理学的理论研究和教育，特别是在驱动和活性物质领域。“活性物质”这个名字最近被创造出来，指的是由许多相互作用的单元组成的软材料，这些单元单独消耗能量，共同产生运动或机械应力。例子包括细菌悬浮液、活细胞的细胞骨架、底物或软弹性基质上的细胞集合，甚至是单层的振动颗粒棒。这些系统表现出大规模的现象和新的机械特性，这可能是对其组成部分的了解所无法预料的。它们可以用凝聚态物质和统计物理的工具在理论上描述为“活的”软材料。该奖项支持研究在控制大量游泳微生物的有组织集体运动中物理和生化机制的相互作用，目的是阐明自组织与随机游泳相比的生物学优势。一个相关的项目侧重于能够自发移动的细胞的行为，在软基质上或嵌入在软的三维凝胶中，目的是了解基质在控制集体细胞迁移、组织和分选中的作用，最终导致组织形成。我们将积极招募弱势群体和本科生参与本研究项目。

TECHNICAL SUMMARYThis award supports theoretical research and education in soft condensed matter and biological physics, specifically in the field of driven and active matter. The name "active matter" has recently been coined to refer to soft materials composed of many interacting units that individually consume energy and collectively generate motion or mechanical stresses. Examples include bacterial suspensions, the cytoskeleton of living cells, collections of cells on a substrate or in a soft elastic matrix, and even monolayers of vibrated granular rods. These systems exhibit large-scale emergent behavior with transitions between ordered and disordered states, pattern formation, and novel rheological and mechanical properties. They can be described theoretically as a new "living" soft material using the tools of condensed matter and statistical physics. A major objective of the project is disentangling the role of purely physical interactions, such as excluded volume effects or medium-mediated hydrodynamic couplings, from that of genetically of biochemically-regulated signaling or of external symmetry-breaking effects, such as chemotaxis, in controlling the emergent behavior of collections of living organisms. This important question has implications ranging from the understanding of biofilm formation to the modeling of wound healing and tissue formation. The award supports research to: (1) use analogies with magnetic and liquid crystalline systems to model pattern formation and swarming in collections of swimming micro-organisms, understand the rheology of these living systems, and investigate the similarities between collections of living and inanimate self-propelled units; (2) model the behavior of motile cells on soft substrates or in three-dimensional gels, with the goal of understanding the role of the matrix or substrate elasticity in controlling collective cell migration, organization and sorting, ultimately leading to tissue formation; (3) understand transport in conventional soft matter, such as colloidal gels and glasses, that is driven out of equilibrium by an external force, such as an electric field, and where translational invariance is broken by material disorder. Members of underrepresented groups and undergraduate students will be actively recruited to participate in this research project. NON-TECHNICAL SUMMARYThis award supports theoretical research and education in soft condensed matter and biological physics, specifically in the field of driven and active matter. The name "active matter" has recently been coined to refer to soft materials composed of many interacting units that individually consume energy and collectively generate motion or mechanical stresses. Examples include bacterial suspensions, the cytoskeleton of living cells, collections of cells on a substrate or in a soft elastic matrix, and even monolayers of vibrated granular rods. These systems exhibit large-scale phenomena and novel mechanical properties that might be unexpected from knowledge of their constituent parts. They can be described theoretically using the tools of condensed matter and statistical physics as "living" soft materials. This award supports research to understand the interplay of physical and biochemical mechanisms in controlling the organized collective motion of a large number of swimming micro-organisms, with the goal of shedding light on the biological advantage of self-organization as compared to random swimming. A related project focuses on the behavior of cells that can spontaneously move, on soft substrates or embedded in soft three-dimensional gels, with the goal of understanding the role of the matrix in controlling collective cell migration, organization and sorting, ultimately leading to tissue formation.Members of underrepresented groups and undergraduate students will be actively recruited to participate in this research project.