Nonlinear Dynamics and Pattern Formation in Physics and Biology

9812526 Goldstein该奖项支持物理和生物系统中非线性动力学和模式形成的研究。与实验紧密联系的理论研究将集中在细胞生长和运动领域，以及流体力学中瑞利不稳定性的另一种解释。第一个领域的工作重点是了解枯草芽孢杆菌细胞生长的物理机制，以及在有氮鞭毛的细菌细胞中定向游动的机制。这项工作将阐明枯草芽孢杆菌在细胞分裂后无法分离时形成超螺旋结构的物理过程，以及与移动丝状结构相关的物理生物学。第二个领域的工作旨在阐明定向游泳的机制，当同向旋转的螺旋鞭毛捆绑在一起时产生。调查将集中在发生这种情况时发生的流体动力学相互作用以及最近在游泳微生物悬浮液中观察到的集体行为。PI寻求在低雷诺数下融合弹性和流体动力学领域的描述，以阐明微生物游泳的物理机制。最近对膜泡形状不稳定性的实验表明，在这种张力驱动的不稳定性中可能发生锋传播。在这些实验的激励下，PI将研究在粘性两相流中可能发生类似的“传播拓扑跃迁”的情况。特别感兴趣的是射流和羽流的对流不稳定性，射流中的屈曲现象，粘弹性和剪切的作用。这位有才华的PI将在物理学和生物学交界的领域进行理论研究。微生物游动的物理机制和更好地理解生物系统特有的各种流体流动是研究的主要焦点。＊＊＊

9812526 Goldstein This award supports research on nonlinear dynamics and pattern formation in physical and biological systems. Theoretical research well connected with experiment will focus on the areas of cell growth and motion, and on an alternative explanation of the Rayleigh instability in fluid mechanics. Work in the first area focuses on understanding the physical mechanisms of cell growth in the bacterium B. subtilis and on the mechanism of directed swimming in peritrichously flagellated bacterial cells. The proposed work would elucidate the physical processes that lead to the formation of the supercoiled structure of B. subtilis that results when cell separation fails to occur after cell division, and related physical biology associated with moving filamentary structures. Work in the second area seeks to elucidate the mechanism for directed swimming that results when co-rotating helical flagella bundle together. Inquiry will focus on the hydrodynamic interactions that occur when this happens and on collective behavior recently observed in suspensions of swimming microorganisms. The PI seeks a description that melds the areas of elasticity and hydrodynamics at low Reynolds number to elucidate the physical mechanisms by which microorganisms swim. Recent experiments on shape instabilities of membrane vesicles induced by optical traps that have shown that front propagation may occur in such tension driven instabilities. Motivated by these experiments, the PI will study the circumstances under which an analogous `propagating topological transition' might occur in viscous two-phase flow. Of particular interest are convective instabilities of jets and plumes, buckling phenomena in jets, and the role of viscoelasticity and shear. %%% This talented PI will carry out theoretical research in areas at the interface between physics and biology. The physical mechanisms by which microorganisms swim and a better understanding of kinds of fluid flow peculiar t o biological systems are a major focus of the research. ***