Research Letters in Physics最新文献

{"title":"Quantum Transitions by Change of Parameters and in Noninertial Motion","authors":"M. Apostol","doi":"10.1155/2008/570167","DOIUrl":"https://doi.org/10.1155/2008/570167","url":null,"abstract":"As it is well known, a quantum system depending on parameters exhibits the (geometric) Berry phase when parameters \u0000are varying in the adiabatic limit. A generalization of the Berry phase is given in the present paper for a nonadiabatic \u0000change of parameters, which leads to quantum transitions in the system. This generalization is applied to \u0000noninertial motions and it is shown that such motions may induce quantum transitions for a system in an external \u0000field governed by Schrodinger's equation.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128400849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural, Elastic, and Electronic Properties of ReB2: A First-Principles Calculation","authors":"R. Long, Ying Dai, Hao Jin, Baibiao Huang","doi":"10.1155/2008/293517","DOIUrl":"https://doi.org/10.1155/2008/293517","url":null,"abstract":"The structural, elastic, and electronic properties of the hard material ReB2 have been investigated by means of density functional theory. The calculated equilibrium structural parameters of ReB2 are in agreement with the experimental results. Our result of bulk modulus shows that it is a low compressible material. Furthermore, the elastic anisotropy is discussed by investigating the elastic stiffness constants. The charge density and the electronic properties indicate that the covalent bonding of Re-B and B-B plays an important role in formation of a hard material. The good metallicity and hardness of ReB2 might serve as hard conductors.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131147535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physics of Superpulses in Storage Ring Free-Electron Lasers","authors":"V. Litvinenko","doi":"10.1155/2008/592869","DOIUrl":"https://doi.org/10.1155/2008/592869","url":null,"abstract":"Contradictory to the widespread perception, storage ring free-electron lasers with substantial net gain can generate peak lasing power reaching GW levels in the so-called superpulse mode. This power level is sufficient for studies of nonlinear processes and efficient intracavity harmonic generation. This letter describes the physics of the superpulses and a phase-space refreshment in the electron beam responsible for this phenomenon.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130906186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanopinholes-Based Optical Superlens","authors":"Yongqi Fu, C. Du, Wei Zhou, L. Lim","doi":"10.1155/2008/148505","DOIUrl":"https://doi.org/10.1155/2008/148505","url":null,"abstract":"A type of nanopinhole-based plasmonic structure is presented. It can realize superfocusing within micron-scale propagation distance with spatial resolution beyond diffraction limit. Cut-off wavelength effect is highlighted for understanding how periodicity distribution of the nanopinholes influences transmission and focusing through the structure. Redshift peak transmission occurs while the periodicity increases. In addition, focusing property of the plasmonic structures is analyzed for the monochromatic illumination with different incident wavelengths ranging from 400 nm to 750 nm. The easy fabrication and high focusing performance of the proposed structures may be used in data storage devices, bioimaging, and nanolithography.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"39 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132933909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Spheroidal Semiseparation for Stokes Flow","authors":"G. Dassios, P. Vafeas","doi":"10.1155/2008/135289","DOIUrl":"https://doi.org/10.1155/2008/135289","url":null,"abstract":"Many heat and mass transport problems involve particle-fluid systems, where the assumption of Stokes flow provides a very good approximation for representing small particles embedded within a viscous, incompressible fluid characterizing the steady, creeping flow. The present work is concerned with some interesting practical aspects of the theoretical analysis of Stokes flow in spheroidal domains. The stream function 𝜓, for axisymmetric Stokes flow, satisfies the well-known equation 𝐸4𝜓=0. Despite the fact that in spherical coordinates this equation admits separable solutions, this property is not preserved when one seeks solutions in the spheroidal geometry. Nevertheless, defining some kind of semiseparability, the complete solution for 𝜓 in spheroidal coordinates has been obtained in the form of products combining Gegenbauer functions of different degrees. Thus, the general solution is represented in a full-series expansion in terms of eigenfunctions, which are elements of the space 𝑘𝑒𝑟𝐸2 (separable solutions), and in terms of generalized eigenfunctions, which are elements of the space 𝑘𝑒𝑟𝐸4 (semiseparable solutions). In this work we revisit this aspect by introducing a different and simpler way of representing the aforementioned generalized eigenfunctions. Consequently, additional semiseparable solutions are provided in terms of the Gegenbauer functions, whereas the completeness is preserved and the full-series expansion is rewritten in terms of these functions.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121293931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Light Emitting Diodes of Inverse Spin Valves","authors":"X. R. Wang","doi":"10.1155/2008/434936","DOIUrl":"https://doi.org/10.1155/2008/434936","url":null,"abstract":"Light emitting diodes made out of inverse spin valves of a ferromagnetic half metal sandwiched between two nonmagnetic metals are proposed. Based on a giant spin-dependent chemical potential difference created under an external bias, the inverse spin valves are possible to emit light when electrons with the higher chemical potential flip their spins and become the electrons of the opposite spin with the lower chemical potential. The frequency of this type of light emitting diodes is tunable by the bias.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122578082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Dyon Charge in Noncommutative Gauge Theories","authors":"L. Cieri, F. Schaposnik","doi":"10.1155/2008/890916","DOIUrl":"https://doi.org/10.1155/2008/890916","url":null,"abstract":"We construct a dyon solution for the noncommutative version of the Yang-Mills-Higgs model with a 𝜗-term. Extending the Noether method to the case of a noncommutative gauge theory, we analyze the effect of CP violation induced both by the 𝜗-term and by noncommutativity proving that the Witten effect formula for the dyon charge remains the same as in ordinary space.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132288694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduction of Time-Dependent Schrödinger Equations with Effective Mass to Stationary Schrödinger Equations","authors":"A. Schulze-Halberg","doi":"10.1155/2008/589269","DOIUrl":"https://doi.org/10.1155/2008/589269","url":null,"abstract":"Schrodinger equations with effective mass occur in the context of transport phenomena in crystals (e.g., semiconductors), where the electrons are not completely free, but interact with the potential of the lattice. The quantum dynamics of such electrons can be modeled by an effective mass, the behavior of which is determined by the band curvature [1–3]. Since the effective mass Schrodinger equation takes a more complicated form than the conventional Schrodinger equation [4], the identification of solvable cases is more difficult. In the stationary case, particular potentials with effective mass have been studied mainly by means of point canonical transformations [5–7] and Darboux transformations (resp., supersymmetric factorization) [8–10]. Recently, these methods have also been elaborated for the fully timedependent case [11–13]. However, the main problem of accessing time-dependent Schrodinger equations (TDSE) with effective mass is the lack of known solvable cases. In order to attack this problem for noneffective (constant) mass, it has been shown that for a certain class of potentials, the TDSE with constant mass can be mapped onto a stationary Schrodinger equation [14], such that each solvable stationary Schrodinger equation generates a solvable TDSE. Whereas in [14] the most general class of reducible potentials is derived, particular cases have been obtained earlier, for example, for time-dependent harmonic oscillator potentials with travelling-wave terms [15]. The method of mapping time-dependent onto stationary problems has also been used for the calculation of Green’s functions for timedependent Coulomb and other potentials [16]. The purpose of the present note is to generalize the results in [14] to the effective mass case. We identify a class of potentials for which the effective mass TDSE can be reduced to a stationary Schrodinger equation by means of a point canonical transformation. Thus, each solvable stationary Schrodinger equation gives rise to a solvable effective mass TDSE. This allows the straightforward generation of time-dependent potentials with effective masses and their corresponding solutions. Furthermore, our transformation preserves L2-normalizability, such that physical solutions are taken into physical solutions. In the remainder of this note, we first give the point canonical transformation that relates effective mass TDSEs and stationary Schrodinger equations to each other. We prove its correct simplification for constant mass and show that L2-normalizability of the solutions is preserved. In the final paragraph we present an application.","PeriodicalId":341677,"journal":{"name":"Research Letters in Physics","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132744271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}