Experimental Study of Adaptation to the Edge of Chaos and Critical Scaling in the Self-adjusting Peroxidase-Oxidase Reaction

自调节过氧化物酶-氧化酶反应中适应混沌边缘和临界尺度的实验研究

• 批准号: 0140179
• 负责人: Alfred Hubler
• 金额: $ 16.79万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0140179&HistoricalAwards=false
• 关键词: Experimental; Study; Adaptation; Edge; Chaos

0140179Hubler One aspect of biocomplexity is the ability of biota to self-adjust to theirenvironment. Previous studies of adaptive behavior have shown thatadaptive systems will evolve over time to states that are weakly chaotic, acondition known as the edge of chaos. These studies typically use agenetic algorithm (computer-based evolution) to implement adaptation. Itis conjectured that most self-adjusting dynamical systems that initiallyhave chaotic behavior will also adapt toward the edge of chaos. A modelfor self-adjusting dynamical systems is introduced which treats the controlparameters as slowly varying, rather than constant. The dynamics of theseparameters is assumed to be governed by some low-pass filtered feedbackfrom the dynamical variables of the system. Under the influence of noise,at least in numerical models, the probability of chaotic breakout shows auniversal scaling with the duration of the breakouts.Applications of the model to biochemical oscillators as the simplestpossible adaptive system relevent to environmental dynamics will beinvestigated. A high degree of interdisciplinarity is required, as theresearch involves expertise in dynamical systems, plant biology,instrumental measurements, cybernetics, enzymology, chemistry, and physics. The system is chosen to be "biocomplex," yet simple enough that meaningfulmeasurements can be made and quantitative models can be evaluated.We intend to experimentally demonstrate adaptation using theperoxidase-oxidase oscillator as an example. This system is known toexhibit non-linear, complex, and even chaotic behavior. We will explore ifthe in situ behavior of this enzyme provides the first experimentalevidence for adaptation to the edge of chaos in a naturally occurringsystem. Detailed chemical models are available to guide our experiments.We will experimentally implement low-pass filtered feedback from thedynamical variables to the control parameters through:1. a computer based probe-actuator system, and 2. the comparatively slow response of the metabolism of a thin section of horseradish root tissues suspended in a reactor, and check for adaptation to the edge of chaos, and critical scaling of chaotic outbreaks of chemical oscillations.Outreach activities to local secondary schools will be incorporated intoour existing collaborations with high school science teachers. If ourinitial experiments on plant peroxidases show the anticipated complexity,we will then explore the related complexity in the behavior of peroxidasesand oxidases in human neutrophils, cells associated with anti-bacterialactivity and response to systemic afronts.

生物复杂性的一个方面是生物群自我适应环境的能力。以前对自适应行为的研究表明，随着时间的推移，自适应系统将进化到弱混沌状态，这种状态被称为混沌边缘。这些研究通常使用非遗传算法(基于计算机的进化)来实现适应。它推测，大多数最初具有混沌行为的自调整动力系统也将适应于混沌的边缘。介绍了一种自调整动态系统模型，该模型将控制参数视为缓变的，而不是恒定的。假设这些参数的动态由来自系统动态变量的一些低通滤波反馈控制。在噪声的影响下，至少在数值模型中，混沌爆发的概率随爆发的持续时间呈现普遍的标度。我们将研究该模型在生化振荡器中的应用，作为与环境动力学相关的最简单的可能的适应系统。需要高度的交叉学科，因为这项研究涉及动力系统、植物生物学、仪器测量、控制论、酶学、化学和物理方面的专业知识。该系统被选择为“生物复杂的”，但足够简单，可以进行有意义的测量和量化模型的评估。我们打算以过氧化物酶-氧化酶振荡器为例进行实验演示适应。众所周知，该系统呈现出非线性、复杂甚至混沌的行为。我们将探索这种酶的原位行为是否为适应自然发生的系统中的混沌边缘提供了第一个实验证据。我们有详细的化学模型来指导我们的实验。我们将通过实验实现从动力学变量到控制参数的低通滤波反馈：1.基于计算机的探测器-执行器系统，以及2.悬浮在反应堆中的辣根组织薄片新陈代谢的相对缓慢的反应，并检查对混沌边缘的适应，以及对化学振荡混沌爆发的临界尺度的适应。我们将把对当地中学的扩展活动纳入我们与高中科学教师的现有合作中。如果我们对植物过氧化物酶的初步实验显示了预期的复杂性，那么我们将探索过氧化物酶和人类中性粒细胞中的氧化物酶行为的相关复杂性，这些细胞与抗菌活性和对全身炎症的反应有关。