Stochastic and Nonlinear Phenomena in Physics and Biology

物理和生物学中的随机和非线性现象

• 批准号: 9819646
• 负责人: Ronald Fox
• 金额: $ 13.5万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9819646&HistoricalAwards=false
• 关键词: Stochastic; Nonlinear; Phenomena; Physics; Biology

The focus of this research proposal is the interplay of stochasticity and nonlinearity in physics and biology. Two projects are in physics and have their origin in earlier studies by the Principal Investigator on the amplification of intrinsic noise by chaos. Two projects are in biology and concern the fundamental constructive role of noise in molecular and cellular mechanisms. Each project involves a combination of methods. Analytic and numerical methods will be used, and contact with experiments will be made wherever possible. One project of each type is described below.1) The classical Lyapunov exponent has been shown by the Principal Investigator to be a quantum signature of classical chaos. This realization depends on the use of Husimi-Wigner distributions that have direct classical analogues as non-negative ensemble densities. Husimi-Wigner wave packets are most easily constructed using generalized coherent states. In this proposal, a new class of coherent states called Klauder states will be studied. Especially interesting are the Klauder states for the Coulomb problem. This work will impact research on quantum-classical correspondence and on experiments with Rydberg atom traps. 2) Rectified Brownian movement is a mechanism by which metabolic Gibbs free energy is converted into useful mechanical work inside cells. Rather than a direct chemo-mechanical conversion in which chemical energy is transduced into work, an indirect mechanism is proposed. In this alternative mechanism, work is done by heat, but not in violation of the second law of thermodynamics. Instead, a diffusion regime is applicable in which the boundary conditions are asymmetric. The asymmetry is paid for with metabolic free energy. The impact of this work will be to potentially provide a unified mechanism for a great many basic cellular processes.

本研究计划的重点是物理学和生物学中随机性和非线性的相互作用。 两个项目属于物理学领域，起源于首席研究员关于混沌放大固有噪声的早期研究。 两个项目属于生物学领域，涉及噪声在分子和细胞机制中的基本建设性作用。每个项目都涉及方法的组合。 将使用分析和数值方法，并尽可能接触实验。下面描述了每种类型的一个项目。1) 首席研究员已证明经典李亚普诺夫指数是经典混沌的量子特征。 这种实现取决于 Husimi-Wigner 分布的使用，该分布具有直接的经典类似物作为非负系综密度。 使用广义相干态最容易构造胡西米-维格纳波包。 在该提案中，将研究一类新的相干态，称为克劳德态。特别有趣的是库仑问题的克劳德态。这项工作将影响量子经典对应和里德伯原子陷阱实验的研究。 2) 修正布朗运动是一种将代谢吉布斯自由能转化为细胞内有用机械功的机制。 提出了一种间接机制，而不是直接将化学能转化为功的化学机械转换。 在这种替代机制中，功是通过热量完成的，但并不违反热力学第二定律。相反，可应用边界条件不对称的扩散机制。 这种不对称性是用代谢自由能来弥补的。这项工作的影响将有可能为许多基本的细胞过程提供统一的机制。