Circular autowaves in human atria and initial conditions for their emergence

Systems of nonlinear parabolic partial differential equations were used for a computational study of circular self-oscillatory processes in the active medium of the atria. The FitzHugh-Nagumo nonlinear differential equation was used in this work. The following excitation pathways of circular reentry waves were considered: 1. Excitation combined with unilateral blockade of excitation; 2. The effect of a part of a simple autowave; 3. Excitation in the tail part of the autowave; and 4. Emergence of a temporarily refractory site in the fixed part of a channel. The pathways of circular autowave excitation listed above provide a comprehensive representation of the currently characterized excitation pathways for this type of wave. The results of computational experiments that illustrate the excitation pathways of circular reentry waves are reported in this work.     

Beyond the Kuramoto-Zel’dovich theory: Steadily rotating concave spiral waves and their relation to the echo phenomenon

In numerical experiments with the Fitzhugh-Nagumo set of reaction-diffusion equations describing two-dimensional excitable media, unusual solutions are found that correspond to a concave spiral wave steadily rotating round a circular obstacle in a finite-size medium. Such a wave arises in the region of parameters corresponding to the solitonlike regime (see text); it appears due to the interaction between the peripheral areas of a “seed” spiral wave with a convex front and the echo waves incoming from the outer boundaries of a medium. The solutions obtained are in contradiction with intuition and represent a numerical counterexample to the known theories that forbid steadily moving excitation waves with concave fronts. Nevertheless, a concave spiral wave is a stable object; being transformed to the usual spiral wave with a convex front by suppressing echo at the outer boundaries of the medium, it is again recovered upon restoring the echo conditions. In addition to the single-arm spiral concave wave, solutions are obtained that describe multiarm waves of this type; for this reason, the concave fronts of these waves are a coarse property.     

Nonlinear modes of parametric vibrations and their applications to beams dynamics

An iterative loop combining nonlinear modes and the Rauscher method is suggested for analyzing finite degree-of-freedom nonlinear mechanical systems with parametric excitation. This method is applied to an analysis of the parametric vibration of beams.     

Nonlinear dynamics of a quasi-one-dimensional spiral structure

The nonlinear dynamics of solitons and spin waves in spiral magnets without inversion centers is investigated using the sine-Gordon model. The possibility of finding solitons in spiral structures is discussed.     

Nonlinear spiral waves in a galactic disk

An analytical solution of the nonlinear dynamic equations for a galactic disk is found. This solution describes the spiral design of spiral galaxies. The logarithmic profile of the spiral design and relatively larger density fluctuations as compared to velocity-field fluctuations are explained. Breaking of the obtained solution takes place for a certain critical amplitude. This can be a mechanism for the formation of galactic shocks and narrow star formation regions.     

核酸识体的研究及应用

核酸识体(aptamer)是近年来发展起来的一类经体外人工进化程序筛选出的寡聚核苷酸。它能高效、特异地结合各种配体，在蛋白质的分析检测、医学诊断治疗、生物传感器和分子开关的开发等方面有很大的应用前景，文章对核酸识体的研究和应用进展进行了综述。     

原子漏斗及其应用

文章简单介绍了磁、光原子漏斗的基本原理，详细综述了各种原子漏斗方案及其实验结果．这些漏斗方案主要包括采用红失谐高斯光束、蓝失谐消逝波光场和空心光束串联而成的光学原子漏斗，采用载流导线的静磁原子漏斗以及采用磁光凝胶构成的磁光原子漏斗．文章最后还简单介绍了原子漏斗在原子光学领域中的潜在应用．     

Pre-symplectic algebroids and their applications

In this paper, we introduce the notion of a pre-symplectic algebroid and show that there is a one-to-one correspondence between pre-symplectic algebroids and symplectic Lie algebroids. This result is the geometric generalization of the relation between left-symmetric algebras and symplectic (Frobenius) Lie algebras. Although pre-symplectic algebroids are not left-symmetric algebroids, they still can be viewed as the underlying structures of symplectic Lie algebroids. Then we study exact pre-symplectic algebroids and show that they are classified by the third cohomology group of a left-symmetric algebroid. Finally, we study para-complex pre-symplectic algebroids. Associated with a para-complex pre-symplectic algebroid, there is a pseudo-Riemannian Lie algebroid. The multiplication in a para-complex pre-symplectic algebroid characterizes the restriction to the Lagrangian subalgebroids of the Levi–Civita connection in the corresponding pseudo-Riemannian Lie algebroid.     

Free-electron lasers and their applications

We review the classical theory of the free-electron laser and discuss possible applications in laser fusion, laser-induced chemistry, biochemistry, and solid-state physics. The possibility of using optical wigglers to reach the VUV and soft X-ray regimes is also analysed.     

原子反射镜及其应用

原子反射镜是人们从事原子光学实验研究的重要器件之一.本文将简单综述采用冷原子磁、光操控技术发展起来的诸如消逝波原子反射镜、半高斯光束原子反射镜、周期性磁化的磁带反射镜、周期性排列的永久磁铁反射镜和载流导线磁反射镜等各种原子反射镜的基本原理、实验方案及其最新进展,并就原子反射镜在原子光学实验中的应用作一简单介绍.     

微等离子体三极管及其应用

一种新型的微电子器件——微等离子体三极管近期被成功研制出来.它的问世奠定了未来更加节能、更加轻便的,具有更高分辨率和更高对比度的等离子体显示的新技术革命基础.文章介绍了微等离子体三极管的工作原理和基本特性,展望了它在发光显示领域的应用前景.     

Brane tilings and their applications

We review recent developments in the theory of brane tilings and four‐dimensional 𝒩 = 1 supersymmetric quiver gauge theories. This review consists of two parts. In part I, we describe foundations of brane tilings, emphasizing the physical interpretation of brane tilings as fivebrane systems. In part II, we discuss application of brane tilings to AdS/CFT correspondence and homological mirror symmetry. More topics, such as orientifold of brane tilings, phenomenological model building, similarities with BPS solitons in supersymmetric gauge theories, are also briefly discussed. This paper is a revised version of the author's master's thesis submitted to Department of Physics, Faculty of Science, the University of Tokyo on January 2008, and is based on his several papers and some works in progress [1–7].     

Infra-red lasers and their applications

Properties and applications of infra-red lasers are reviewed, with particular emphasis on those likely to be fundametnally important in energy production, materials and data processing.     

微纳光纤及其应用

微纳光纤是一种直径接近或小于传输光波长的波导,由物理拉伸方法制得,具有表面光滑、直径均匀性好、机械性能高、强光场约束、强倏逝场、表面场增强效应及反常波导色散等特性,在光通信、激光、传感检测、非线性光学、量子光学等领域具有重要的应用前景。     

Order-N methodologies and their applications

An exhaustive inventory of existing order-N methodologies for the calculation of the total energy as well as the atomic forces up to 1999 has been conducted. These methodologies are discussed in terms of the key approximations involved in each method. Emphasis is placed on the roles played by these approximations and how they affect the accuracy and efficiency of the method. Issues affecting the implementation of various order-N procedures, such as the choice of the tight-binding model in the order-N tight-binding approaches and the construction of the Hamiltonian in the order-N ab initio approaches, are also discussed. Some typical examples of applications of the order-N methods to study problems of realistic sizes are presented to provide a glimpse of the capability of utilizing the order-N methods to predict the stable structures and properties of complex systems with reduced symmetry. This review is expected to serve as a clearinghouse where a single resource is provided to help guide the reader to decide, among the existing methodologies, which method can best fulfill the task at hand.     

螺旋波纹波导回旋行波管注波互作用非线性理论

螺旋波纹波导回旋行波管与采用光滑圆波导的回旋管相比,有较大的带宽。介绍了该类回旋行波管的非线性注波互作用理论。计算结果表明该理论计算结果与实际实验报道的结果基本符合,相应的电子效率达到29%,饱和增益达到37 dB,工作磁场0.21 T,电压185 kV,电流19 A。     

Nonlinear dynamics of breathers in the spiral structures of magnets

The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of “precursors” and “tails” in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.