Iron oxidation, interfacial expansion, and buckling at the Fe/NiO(001) interface

In order to provide a structural basis for a physical understanding of exchange bias in metal/magnetic-oxide interfaces, we have determined the structure of the Fe/NiO(001) interface by means of x-ray absorption spectroscopy and ab initio density functional theory calculations. A Fe-Ni alloyed phase on top of an interfacial FeO planar layer is formed. The FeO layer exhibits a 7% expanded interlayer distance and a 0.3 A buckling; its presence is predicted to increase the spin magnetic moment of the interface Fe atoms by 0.6 mu(B), compared to the ideally abrupt interface.     

Quantum recognition of eigenvalues,structure of devices,and thermodynamic properties

Quantum algorithms that speed up their classical counterparts are proposed for the following problems: recognition of eigenvalues with a fixed precision, recognition of molecular and electronic device structures, and the finding of thermodynamic functions. We mainly consider structures that generate sparse spectra. These algorithms require a time from about the square root to the logarithm of the time of the classical analogues, and they provide exponential savings in memory for the first three problems. For example, the time required for distinguishing two devices with the same given spectrum is about the seventh root of the time of the direct classical method, and about the sixth root for the recognition of an eigenvalue. Microscopic quantum devices can therefore recognize molecular structures and physical properties of environment faster than large classical computers.     

光导在折射率引导光纤、多孔光纤、光子带隙光纤和纳米线中的简要定性解释

本文是一篇教学论文,旨在通过对具体实例中不同物理过程的分析来定性解释光导拓宽固体材料折射率引导光纤光谱、多孔光纤光谱、光子带隙光纤光谱和纳米线光谱的原理。     

Cliffordization, spin, and fermionic star products

Deformation quantization is a powerful tool for quantizing theories with bosonic and fermionic degrees of freedom. The star products involved generate the mathematical structures which have recently been used in attempts to analyze the algebraic properties of quantum field theory. In the context of quantum mechanics they provide a quantization procedure for systems with either bosonic or fermionic degrees of freedom. We illustrate this procedure for a number of physical examples, including bosonic, fermionic, and supersymmetric oscillators. We show how non-relativistic and relativistic particles with spin can be naturally described in this framework.     

Spiral model, jamming percolation and glass-jamming transitions

The Spiral Model (SM) corresponds to a new class of kinetically constrained models introduced in joint works with Fisher [9,10] which provide the first example of finite dimensional models with an ideal glass-jamming transition. This is due to an underlying jamming percolation transition which has unconventional features: it is discontinuous (i.e. the percolating cluster is compact at the transition) and the typical size of the clusters diverges faster than any power law, leading to a Vogel-Fulcher-like divergence of the relaxation time. Here we present a detailed physical analysis of SM, see [6] for rigorous proofs.     

Topological photonic states in gyromagnetic photonic crystals: Physics,properties, and applications

Topological photonic states (TPSs) as a new type of waveguide state with one-way transport property can resist backscattering and are impervious to defects, disorders and metallic obstacles. Gyromagnetic photonic crystal (GPC) is the first artificial microstructure to implement TPSs, and it is also one of the most important platforms for generating truly one-way TPSs and exploring their novel physical properties, transport phenomena, and advanced applications. Herein, we present a brief review of the fundamental physics, novel properties, and practical applications of TPSs based on GPCs. We first examine chiral one-way edge states existing in uniformly magnetized GPCs of ordered and disordered lattices, antichiral one-way edge states in cross magnetized GPCs, and robust one-way bulk states in heterogeneously magnetized GPCs. Then, we discuss the strongly coupling effect between two co-propagating (or counter-propagating) TPSs and the resulting physical phenomena and device applications. Finally, we analyze the key issues and prospect the future development trends for TPSs in GPCs. The purpose of this brief review is to provide an overview of the main features of TPSs in GPC systems and offer a useful guidance and motivation for interested scientists and engineers working in related scientific and technological areas.     

The Elgin marvel: using magnetic resonance imaging to look at a moldic fossil from the Permian of Elgin, Scotland, UK

The successful use of magnetic resonance imaging (MRI) of a moldic fossil dicynodont from the Permian aeolian Hopeman Sandstone Formation of Elgin, Scotland, UK, provides paleontologists with a nondestructive technique for examining fossils preserved in this fashion. For large moldic fossils, medical scanners such as the Phillips Gyroscan MRI, provide adequate resolution for gross morphologic determination. The 3-D rendered images using software such as Philips Easivision allows the fossil to be examined and dissected without causing any physical damage to the original material. From the scans it is also possible to produce 3-D stereolithographs for a more tactile manipulation of the renderings.     

Exons, introns, and DNA thermodynamics

The genes of eukaryotes are characterized by protein coding fragments, the exons, interrupted by introns, i.e., stretches of DNA which do not carry useful information for protein synthesis. We have analyzed the melting behavior of randomly selected human cDNA sequences obtained from genomic DNA by removing all introns. A clear correspondence is observed between exons and melting domains. This finding may provide new insights into the physical mechanisms underlying the evolution of genes.     

超声分子束注入模型与流体输运程序的耦合

将超声分子束注入模型加入到流体输运程序ONETWO 中,为ONETWO 程序提供了重要的粒子源和电子、离子热源项。在ONETWO 程序物理模型中加入超声分子束注入模型,修改TPSMBI 程序并将其耦合到 ONETWO 程序中。运用耦合后的ONETWO 程序模拟研究了喷气法与超声分子束注入产生的源项。将超声分子束注入模型加入到ONETWO 程序中不仅可以为相关的实验分析提供一种重要的工具,也可为未来装置(如中国聚变工程实验堆)的物理设计提供重要的粒子和能量源信息。     

Noble Metal Clusters: Applications in Energy,Environment, and Biology

Sub‐nanometer‐sized metal clusters, having dimensions between metal atoms and nanoparticles, have attracted tremendous attention in the recent past due to their unique physical and chemical properties. As properties of such materials depend strongly on size, development of synthetic routes that allows precise tuning of the cluster cores with high monodispersity and purity is an area of intense research. Such materials are also interesting owing to their wide variety of applications. Novel sensing strategies based on these materials are emerging. Owing to their extremely small size, low toxicity, and biocompatibility, they are widely studied for biomedical applications. Primary focus of this review is to provide an account of the recent advances in their applications in areas such as environment, energy, and biology. With further experimental and theoretical advances aimed at understanding their novel properties and solving challenges in their synthesis, an almost unlimited field of applications can be foreseen.     

Novel electrodynamic trapping mechanism for neutral,polar particles

A conceptually new trapping mechanism for neutral, polar particles is introduced and discussed. Unlike existing mechanisms that are based on oscillating saddle-point potentials or rotating electric dipole fields, the new mechanism is based on a superposition of ac and dc electric monopolefields that dynamically generate a minimum of the effective ponderomotive potential in which the particles are trapped. Extensive numerical simulations of the dynamics and the stability properties of trapped HC₁₇N molecules and ferroelectric rods (made of barium titanate or croconic acid crystals) prove the validity of the new mechanism. The examples show that the same mechanism is applicable to the trapping of macroscopic as well as microscopic particles. The numerical results are backed by a physical pseudo-potential picture and an analytical stability analysis that provide physical insight into why and how the new mechanism works. A semi-quantum, Born-Oppenheimer-type calculation that treats the intrinsic rotational degree of freedom of HC₁₇N quantum mechanically is also presented. A detailed discussion of engineering aspects shows that laboratory implementation of the new mechanism is within current technological reach.     

Bubbles, shocks and elementary technical trading strategies

In this paper we provide a unifying framework for a set of seemingly disparate models for bubbles, shocks and elementary technical trading strategies in financial markets. Markets operate by balancing intrinsic levels of risk and return. This seemingly simple observation is commonly over-looked by academics and practitioners alike. Our model shares its origins in statistical physics with others. However, under our approach, changes in market regime can be explicitly shown to represent a phase transition from random to deterministic behaviour in prices. This structure leads to an improved physical and econometric model. We develop models for bubbles, shocks and elementary technical trading strategies. The list of empirical applications is both interesting and topical and includes real-estate bubbles and the on-going Eurozone crisis. We close by comparing the results of our model with purely qualitative findings from the finance literature.     

An alternative approach to combination vaccines: intradermal administration of isolated components for control of anthrax,botulism, plague and staphylococcal toxic shock

Background  

Combination vaccines reduce the total number of injections required for each component administered separately and generally provide the same level of disease protection. Yet, physical, chemical, and biological interactions between vaccine components are often detrimental to vaccine safety or efficacy.     

Kinematics of many-particle processes in invariant variables: Physical regions, phase space and all that

The kinematics of processes involving N spinless particles, in terms of invariant variables, are studied by means of Gram determinants. It is proposed that the Gram determinant method may provide a convenient unified treatment for general kinematical purposes. Using this approach, we first obtain the necessary and sufficient conditions for describing the physical regions; their solutions produce a systematic, practical scheme for constructing the physical regions explicitly. Secondly, a simple way of obtaining relations between geometrical and invariant quantities is described; some such relations are exhibited. The application of the Gram-determinant method is illustrated mainly with a discussion on the Toller angle dependence of the reggeon-reggeon-particle vertex function; in particular, we find a certain form of such dependence, in the asymptotic Regge limit, that arises naturally from the internal consistency of multi-Reggeism. Finally, the phase-space factor for many-particle productions is discussed.     

Unified treatment: analyticity,Regge trajectories,Veneziano amplitude,fundamental regions and Moebius transformations

In this paper we present a unified treatment that combines the analyticity properties of the scattering amplitudes, the threshold and asymptotic behaviors, the invariance group of Moebius transformations, the automorphic functions defined over this invariance group, the fundamental region in (Poincaré) geometry, and the generators of the invariance group as they relate to the fundamental region. Using these concepts and techniques, we provide a theoretical basis for Veneziano type amplitudes with the ghost elimination condition built in, related the Regge trajectory functions to the generators of the invariance group, constrained the values of the Regge trajectories to take only inverse integer values at the threshold, used the threshold behavior in the forward direction to deduce the Pomeranchuk trajectory as well as other relations. The enabling tool for this unified treatment came from the multi-sheet conformal mapping techniques that map the physical sheet to a fundamental region which in turn defines a Riemann surface on which a global uniformization variable for the scattering amplitude is calculated via an automorphic function, which in turn can be constructed as a quotient of two automorphic forms of the same dimension. Received: 22 October 2002 / Revised version: 19 February 2003 Published online: 23 May 2003 RID="a" ID="a" e-mail: arc@lucent.com     

大学物理网络个性化教学研究

随着计算机网络技术的发展,开发网络教学平台进行教学已成为目前高校提高教学质量的重要的途径之一.但目前现有的网络课程大多在个性化教学、因材施教方面存在诸多问题,本文建议在大学物理网络教学平台的构建中使用数据挖掘技术,为实施个性化教学提供决策支持.本文介绍了数据挖掘技术及其常用方法,并列举了数据挖掘技术在大学物理网络课程中的应用实例.