Wigner-type symmetries and their extensions in nuclear physics

Wigner’s work on the SU ^ST (4) symmetry inspired the introduction of many other symmetries in nuclear physics. Here the concept of dynamical (ly broken) symmetry (like SU ^ST (4)) is reviewed, with some examples from nuclear clusterization.     

The fundamental constants in physics and their time dependence

We discuss the fundamental constants in the Standard Model of particle physics. Furthermore we discuss possible changes of these constants on the cosmological time scale. The Grand Unification of the observed strong, electromagnetic and weak interactions implies relations between the time variations of the finestructure constant α and of the QCD scale Λ_c. A change of α by 10⁻¹⁵/year, as seen by an astrophysics experiment, implies a time variation of Λ_c of at least 10⁻¹⁵/year. An experiment in Quantum Optics, which was designed to look for a time variation of Λ_c, is discussed.     

光晶格原子钟及其在基础物理学中的应用

光晶格原子钟已经实现了10^-18量级的系统不确定度和10^-19量级的频率稳定度,是下一代“秒”定义的候选装置之一。凭借优异的系统性能,光晶格原子钟逐渐在基础物理研究领域发挥重要作用。文章综述了光晶格原子钟的研究背景、工作原理、关键实验技术及其在基础物理研究等方面的应用。     

Search for new physics using high-mass tau pairs from 1.96 TeV pp collisions

We present the results of a search for anomalous resonant production of tau lepton pairs with large invariant mass, the first such search using the CDF II Detector in Run II of the Tevatron pp collider. Such anomalous production could arise from various new physics processes. In a data sample corresponding to 195 pb(-1) of integrated luminosity we predict 2.8+/-0.5 events from standard model background processes and observe 4. We use this result to set limits on the production of heavy scalar and vector particles decaying to tau lepton pairs.     

海啸的物理

地震海啸的产生是地球表面固体层和流体层相互作用的结果.文章介绍了这种相互作用的物理过程,讨论了海啸的大小、能量、传播速度.指出：建立早期预警系统是减少海啸灾害的重要措施,目前的预警系统虚报率很高的问题,仍需要通过加强地球表层系统相互作用的研究来解决.     

海啸的物理

地震海啸的产生是地球表面固体层和流体层相互作用的结果．文章介绍了这种相互作用的物理过程，讨论了海啸的大小、能量、传播速度．指出：建立早期预警系统是减少海啸灾害的重要措施，目前的预警系统虚报率很高的问题，仍需要通过加强地球表层系统相互作用的研究来解决．     

Spectral sideband distribution asymmetry in fiber laser

A ring fiber laser with SESAM mode-locking mechanism is constructed. The spectral sideband distribution asymmetry of solitons is observed in the fiber laser. There are different order sidebands distributed in two edges of the soliton spectrum. Through experimentally studying the effect of the different gain media lengths on the mode-locked solitons, it is found that the spectral sideband asymmetry occurs at the long wavelength band of erbium-doped fiber (EDF) gain profile. The origin of sideband asymmetry is owing to the secondary amplification gain profile of EDF, which is pumped by the first gain peak at 1530 nm. Furthermore, an extra in-line polarizer is imported in the cavity for studying the effect of the polarization bias on sidebands. It is found that the polarization bias in the cavity is an important control method to adjust the power and generate the spectral sidebands. However, the polarization bias does not decide the generation of spectral sideband distribution asymmetry.     

Dynamic sideband generation in soliton fiber lasers

We show numerically that when a soliton circulating in the laser cavity experiences dynamical bifurcations, extra sets of sidebands appear in the soliton spectrum. The new sidebands have clearly different characteristics to those of the conventional soliton sidebands, indicating that there exists a new mechanism of sideband generation in the lasers.     

半导体微结构物理效应及其应用讲座 第2讲 量子阱、超晶格物理及其在光电子领域中的应用

文章介绍了半导体量子阱、超晶格的基本物理，以及它在光电子领域中的应用，包括量子阱、量子线、量子点、激光器、光调制器、自电光效应器件、量子点器件等．     

Single sideband imaging in high-resolution electron microscopy

More then 20 years ago, Hanßen and Morgenstern [1] described the case of single sideband imaging in electron microscopy. Single sideband imaging allows to correct artifacts in the imaging process due to spherical aberration and defocus and to reconstruct the electron wave function at the exit surface of the sample from experimental micrographs. In the present work, optimized imaging parameters allowed us to obtain new experimental results, thus confirming the resolution limit of single sideband imaging (0.13 nm) to be close to the information limit of a JEOL 4000EX microscope. Furthermore, the reconstructed exit surface wave functions were throuroughly checked by using them to calculate a focus series, which was compared with an experimental focus series.     

Non-linear Landau resonance interaction and sideband growth

The time development of the distribution function resulting from the Landau resonance interaction between the particles and a narrow band whistler mode wave packet shows a fine structure in the distribution leading to sideband growth of the wave.     

Resonant sideband generation in stretched-pulse fiber lasers

Resonant sideband production in stretched-pulse fiber lasers operating with net normal dispersion is investigated. A theoretical formulation is compared with numerical modeling and experimental results. The inherent difference from sideband generation in soliton lasers is discussed. We also consider the implications of sideband formation in related dispersion-managed soliton transmission systems.     

医药类专业物理课程教学存在的问题及对策

根据对国内69所普通高等院校医药类专业（本科）物理课程教学现状调查的结果,分析了在我国高等教育进入“大众化教育”的形势下,医药类专业物理课程教学中存在的4个急需解决的问题,指出了医药类专业物理课程教学改革的方向,并介绍了我们所做的一些工作。     

Monodomain and polydomain helicoids in chiral liquid-crystalline phases and their biological analogues

Many natural composites exhibit an architecture known as twisted plywood which imparts to them a superior set of physical properties. The origin of this structure is complex and not yet understood. However, it is thought to involve a lyotropic chiral nematic liquid-crystalline mesophase. Indeed, striking structural similarities have been observed and reported between biological fibrous composites and ordered fluids. In this work, a mathematical model based on the Landau-de Gennes theory has been developed to investigate the role played by constraining surfaces in the structural development of a composite material that experiences a liquid-crystalline state during the early steps of its morphogenesis. The goal of this study is to verify the need for an initial constraining surface in the formation of monodomain twisted plywoods as hypothesized by Neville (Tissue & Cell 20, 133 (1988); Biology of Fibrous Composites (Cambridge University Press, 1993)). The numerical simulations qualitatively confirm this theory and highlight the important role that modelling of liquid-crystalline self-assembly plays in the study of tissue morphogenesis.Received: 15 September 2003, Published online: 11 November 2003PACS: 61.30.-v Liquid crystals - 61.30.Dk Continuum models and theories of liquid crystal structure - 61.30.Mp Blue phases and other defect-phases - 61.30.St Lyotropic phases     

Synthesis of 1,2,3-triazolyl nucleoside analogues and their antiviral activity

Molecular Diversity - Based on the fact that a search for influenza antivirals among nucleoside analogues has drawn very little attention of chemists, the present study reports the synthesis of a...     

Regular black holes with improved energy conditions and their analogues in fluids

On the premise of the importance of energy conditions for regular black holes, we propose a method to remedy those models that break the dominant energy condition, e.g., the Bardeen and Hayward black holes. We modify the metrics but ensure their regularity at the same time, so that the weak, null, and dominant energy conditions are satisfied, with the exception of the strong energy condition. Likewise, we prove a no-go theorem for conformally related regular black holes, which states that the four energy conditions can never be met in this class of black holes. In order to seek evidences for distinguishing regular black holes from singular black holes, we resort to analogue gravity and regard it as a tool to mimic realistic regular black holes in a fluid. The equations of state for the fluid are solved via an asymptotic analysis associated with a numerical method, which provides a modus operandi for experimental observations, in particular, the conditions under which one can simulate realistic regular black holes in the fluid.