Introduction to Focus Issue: nonlinear and stochastic physics in biology

Frank Moss was a leading figure in the study of nonlinear and stochastic processes in biological systems. His work, particularly in the area of stochastic resonance, has been highly influential to the interdisciplinary scientific community. This Focus Issue pays tribute to Moss with articles that describe the most recent advances in the field he helped to create. In this Introduction, we review Moss's seminal scientific contributions and introduce the articles that make up this Focus Issue.     

Introduction to focus issue: dynamics in systems biology

The methods of nonlinear systems form an extensive toolbox for the study of biology, and systems biology provides a rich source of motivation for the development of new mathematical techniques and the furthering of understanding of dynamical systems. This Focus Issue collects together a large variety of work which highlights the complementary nature of these two fields, showing what each has to offer the other. While a wide range of subjects is covered, the papers often have common themes such as "rhythms and oscillations," "networks and graph theory," and "switches and decision making." There is a particular emphasis on the links between experimental data and modeling and mathematical analysis.     

趋向统一发展的团簇科学

团簇科学在发展过程中，从原子核物理、凝聚态物理和量子化学等引入许多概念和方法，构成团簇研究的中心议题，逐渐形成一门介于原子分子物理和凝聚态物理之间的交叉学科．文章就团簇结构和性质研究的某些最新进展进行了评述，并与原子核和量子点等的性质进行了比较．     

Introduction: optimization in networks

The recent surge in the network modeling of complex systems has set the stage for a new era in the study of fundamental and applied aspects of optimization in collective behavior. This Focus Issue presents an extended view of the state of the art in this field and includes articles from a large variety of domains in which optimization manifests itself, including physical, biological, social, and technological networked systems.     

回音壁微腔光力系统的相干控制与完全相干透射

本文研究了两侧同时输入的回音壁模谐振双微腔光力系统中电磁诱导透明的相干调控.通过改变双微腔两侧探测场的强度比值及相位差,可以有效控制电磁诱导透明窗口的宽度和深度,对探测场的吸收和色散等性质实施显著的影响,并且能够在特殊频率处产生关于探测场的完全相干透射现象.     

Knotting the MECO Network

The Conferences of the Middle European Cooperation in Statistical Physics (MECO) were created as an attempt to establish and maintain an exchange between scientists in the fields of statistical and condensed matter physics from Western and Eastern countries, overcoming the hurdles of the Iron Curtain. Based on personal remembrance and historical resources, the genesis and further development of MECO meetings is described. The annual meetings were interrupted in 1991 by the Yugoslav War but were re-established in 1993 and continue today. Although the fall of the Iron Curtain and the European Research programs changed the situation for the meetings considerably, the ties created by MECO still are useful to help scientific exchange. The history of European (and not only) statistical physics and the history of the MECO are tightly intertwined. It started in a time where an essential breakthrough has been achieved in statistical physics describing the features near phase transitions. In addition to the merging of solid-state physics and field theory concepts, the application of numerical methods (Monte Carlo methods) added a new pillar besides exact solutions and experiments to check theoretical models. In the following, the scientific emphasis (in general) has changed from the traditional fields of the first MECO to complexity and interdisciplinary themes as well.     

基于Boltzmann输运方程的SPECT系统解析建模方法

在单光子发射断层成像(SPECT)中, 为了校正劣化因素的影响, 提高图像质量, 需要对SPECT成像的物理过程进行准确建模. 本文提出了基于Boltzmann输运方程及其Neumann级数解理论的SPECT系统解析建模方法, 并采用数论高维数值积分算法对解析建模公式进行数值求解. 分别对点源、均匀圆柱体模型和NCAT模型进行SPECT投影过程计算, 将其结果与传统的Monte Carlo建模方法进行比较. 结果表明解析建模方法的计算速度和精度综合性能优于Monte Carlo建模方法, 且具有不受统计噪声影响的优点, 因而更适于进行SPECT成像过程的建模.     

从文献分析看物理学科领域的发展重点

文章从文献分析的角度，首先研究了美国、英国政府确定的物理学重点研究领域；其次利用美国科学情报研究所的科学引文热门论文数据库，分析了世界物理学及其交叉学科的热点、新兴的研究前沿和快速突破的领域；最后，提出了分析总结意见。     

Reconstruction of dynamic structures of experimental setups based on measurable experimental data only

Nowadays, massive amounts of data have been accumulated in various and wide fields, it has become today one of the central issues in interdisciplinary fields to analyze existing data and extract as much useful information as possible from data. It is often that the output data of systems are measurable while dynamic structures producing these data are hidden,and thus studies to reveal system structures by analyzing available data, i.e., reconstructions of systems become one of the most important tasks of information extractions. In the past, most of the works in this respect were based on theoretical analyses and numerical verifications. Direct analyses of experimental data are very rare. In physical science, most of the analyses of experimental setups were based on the first principles of physics laws, i.e., so-called top-down analyses. In this paper, we conducted an experiment of "Boer resonant instrument for forced vibration"(BRIFV) and inferred the dynamic structure of the experimental set purely from the analysis of the measurable experimental data, i.e., by applying the bottomup strategy. Dynamics of the experimental set is strongly nonlinear and chaotic, and it's subjects to inevitable noises. We proposed to use high-order correlation computations to treat nonlinear dynamics; use two-time correlations to treat noise effects. By applying these approaches, we have successfully reconstructed the structure of the experimental setup, and the dynamic system reconstructed with the measured data reproduces good experimental results in a wide range of parameters.     

Introduction: Mapping and control of complex cardiac arrhythmias

This paper serves as an introduction to the Focus Issue on mapping and control of complex cardiac arrhythmias. We first introduce basic concepts of cardiac electrophysiology and describe the main clinical methods being used to treat arrhythmia. We then provide a brief summary of the main themes contained in the articles in this Focus Issue. In recent years there have been important advances in the ability to map the spread of excitation in intact hearts and in laboratory settings. This work has been combined with simulations that use increasingly realistic geometry and physiology. Waves of excitation and contraction in the heart do not always propagate with constant velocity but are often subject to instabilities that may lead to fluctuations in velocity and cycle time. Such instabilities are often treated best in the context of simple one- or two-dimensional geometries. An understanding of the mechanisms of propagation and wave stability is leading to the implementation of different stimulation protocols in an effort to modify or eliminate abnormal rhythms. (c) 2002 American Institute of Physics.     

Coupled continuous-time random walk approach to the Rachev-Rüschendorf model for financial data

In this paper we expand the Rachev-Rüschendorf asset-pricing model introducing a coupled continuous-time-random-walk-(CTRW)-like form of the random number of price changes. Such a form results from the concept of the random clustering procedure (that resembles the coarse-graining methods of statistical physics) and, on the other hand, indicates applicability of the CTRW idea, widely used in physics to model anomalous diffusion, for describing financial markets. In the framework of the proposed model we derive the limiting distributions of log-returns and the corresponding pricing formulas for European call option. In order to illustrate the obtained theoretical results we present their fitting with several sets of financial data.     

Progress of visualization

Visualization is an interdisciplinary imaging technique devoted to make the invisible visible by the techniques of experimental and computer-aided visualizations. It is applicable to various phenomena such as flow, heat, sound, electromagnetism, chemical kinetics and any of their combinations. This review describes the process of development, the present state and fruit of application, and the expectation of future development of visualization using examples. These examples expand to a wide range of fields including engineering, physics, medical science, agriculture, oceanography, meteorology and sports science.     

Nuclear physics and ideas of quantum chaos

The field nowadays called “many-body quantum chaos” was started in 1939 with the article by I.I. Gurevich studying the regularities of nuclear spectra. The field has been extensively developed recently, both mathematically and in application to mesoscopic systems and quantum fields. We argue that nuclear physics and the theory of quantum chaos are mutually beneficial. Many ideas of quantum chaos grew up from the factual material of nuclear physics; this enrichment still continues to take place. On the other hand, many phenomena in nuclear structure and reactions, as well as the general problem of statistical physics of finite strongly interacting systems, can be understood much deeper with the help of ideas and methods borrowed from the field of quantum chaos. A brief review of the selected topics related to the recent development is presented.     

Introduction to focus issue on "randomness, structure, and causality: measures of complexity from theory to applications"

We introduce the contributions to this Focus Issue and describe their origin in a recent Santa Fe Institute workshop.     

核医学的发展及其与相关学科的关系

核基学是一门多学科相结合的交叉学科。核医学由临床核医学、实验核医学及核医学物理３部分组成。核医学在医疗保健及战胜疾病中发挥了重要作用。核医学所取得的成就和成果与许多相关学科有关,尤其是核物理、核探测技术及计算机科学。２１世纪,核医学的发展面临良好的机遇,但也有严峻的挑战。多学科的渗透和广大物理学专家的积极参与将对核医学的发展做出巨大的贡献。     

地震预测与统计物理

将现代统计物理学的理论和方法应用于地震和地震预测问题的研究，近年来取得了长足的进展，成为物理学和地震学之间一个最为活跃的交叉领域，这一领域所取得的成果，例如，将地震作为一种临界现象的模型，不仅丰富和深化了对地震的认识，而且改变了地震预测研究中的一些传统观念。文章介绍了这方面的研究进展，讨论了与这一领域相关的一些重要的物理概念和悬而未决的科学问题。     

复杂系统重构

远离平衡态的开放复杂系统遍及自然、社会和技术领域,是复杂性科学的主要研究对象.通过与外界的能量和物质交换,复杂系统通过自组织形成了多种多样的内在结构、秩序和规律,对认识和预测复杂系统提出了艰巨的挑战.随着实验技术的提高和科技的进步,反映和体现各种复杂系统机理的数据呈指数增长,为研究复杂系统提供了新的机遇.通过系统行为表象数据,揭示复杂系统结构和动力学属于物理领域的反问题,是认识复杂系统的基础,是预测系统状态演化的前提,对于实现系统状态的调控必不可少.然而,复杂系统的多样性和复杂性给解决这一反问题造成了极大的困难.因此,需要开阔思路,借助多学科的交叉与融合,充分挖掘数据中隐藏的知识和深层次机理.本文综述了近年来复杂系统,特别是复杂结构重构和推断方面的研究成果,希望能够启发复杂系统反问题方面的创新.同时,也希望呼吁各领域学者都能关注复杂系统反问题,推动自然、社会、经济、生物、科技领域的交叉与融合,解决大家共同面对的科学问题.