Anomalous Rashba spin-orbit interaction in InAs/GaSb quantum wells

We investigate theoretically the Rashba spin-orbit interaction in InAs/GaSb quantum wells(QWs). We find that the Rashba spin-splitting (RSS) depends sensitively on the thickness of the InAs layer. The RSS exhibits nonlinear behavior for narrow InAs/GaSb QWs and the oscillating feature for wide InAs/GaSb QWs. The nonlinear and oscillating behaviors arise from the weakened and enhanced interband coupling. The RSS also show asymmetric features respect to the direction of the external electric field.Comment: 3 pages, 4 figures. Appl. Phys. Lett. (in press

Chinese Internet AS-level Topology

We present the first complete measurement of the Chinese Internet topology at the autonomous systems (AS) level based on traceroute data probed from servers of major ISPs in mainland China. We show that both the Chinese Internet AS graph and the global Internet AS graph can be accurately reproduced by the Positive-Feedback Preference (PFP) model with the same parameters. This result suggests that the Chinese Internet preserves well the topological characteristics of the global Internet. This is the first demonstration of the Internet's topological fractality, or self-similarity, performed at the level of topology evolution modeling.Comment: This paper is a preprint of a paper submitted to IEE Proceedings on Communications and is subject to Institution of Engineering and Technology Copyright. If accepted, the copy of record will be available at IET Digital Librar

On the symbolic manipulation and code generation for elasto-plastic material matrices

A computerized procedure for symbolic manipulations and FORTRAN code generation of an elasto-plastic material matrix for finite element applications is presented. Special emphasis is placed on expression simplifications during intermediate derivations, optimal code generation, and interface with the main program. A systematic procedure is outlined to avoid redundant algebraic manipulations. Symbolic expressions of the derived material stiffness matrix are automatically converted to RATFOR code which is then translated into FORTRAN statements through a preprocessor. To minimize the interface problem with the main program, a template file is prepared so that the translated FORTRAN statements can be merged into the file to form a subroutine (or a submodule). Three constitutive models; namely, von Mises plasticity, Drucker-Prager model, and a concrete plasticity model, are used as illustrative examples

The effects of a family non-universal Z-prime boson on B--->pipi decays

Motivated by the measured large branching ratio of $\bar{B}^{0}\to\pi^0\pi^0$ (the so-called "$\pi\pi$" puzzle), we investigate the effects of a family non-universal $Z^{\prime}$ model on the tree-dominated $B\to\pi\pi$ decays. We find that the $Z^{\prime}$ coupling parameter $\zeta_{d}^{LR}\sim0.05$ with a nontrivial new weak phase $\phi_d^L\sim-50^{\circ}$, which is relevant to the $Z^{\prime}$ contributions to the QCD penguin sector $\triangle C_5$, is needed to reconcile the observed discrepancy. Combined with the recent fitting results from $B\to\pi K$, $\pi K^{\ast}$ and $\rho K$ decays, the $Z^{\prime}$ parameter spaces are severely reduced but still not excluded entirely, implying that both the "$\pi\pi$" and "$\pi K$" puzzles could be accommodated simultaneously within such a family non-universal $Z^{\prime}$ model.Comment: 28 pages, 4 figures. References and discussions added. To appear in IJMP

Thermodynamic properties of tetrameric bond-alternating spin chains

Thermodynamic properties of a tetrameric bond-alternating Heisenberg spin chain with ferromagnetic-ferromagnetic-antiferromagnetic-antiferromagnetic exchange interactions are studied using the transfer-matrix renormalization group and compared to experimental measurements. The temperature dependence of the uniform susceptibility exhibits typical ferrimagnetic features. Both the uniform and staggered magnetic susceptibilities diverge in the limit $T\to 0$, indicating that the ground state has both ferromagnetic and antiferromagnetic long-range orders. A double-peak structure appears in the temperature dependence of the specific heat. Our numerical calculation gives a good account for the temperature and field dependence of the susceptibility, the magnetization, and the specific heat for Cu(3-Clpy)$_{2}$(N$_{3}$)$_{2}$ (3-Clpy=3-Chloroyridine).Comment: 8 pages, 12 figures; Replaced with final version accepted in Phys. Rev.

Late recurrence of myopic foveoschisis after successful repair with primary vitrectomy and incomplete membrane peeling

PURPOSE: To report three cases of late recurrence of myopic foveoschisis (MF) after initial successful repair with pars plana vitrectomy and membrane peeling to assess the importance of internal limiting membrane peeling. METHODS: A retrospective noncomparative case series was performed of patients who underwent a primary pars plana vitrectomy by a single surgeon with successful resolution of MF, but eventually underwent repeat pars plana vitrectomy for recurrent MF. Best-corrected visual acuity, fundus photography, and optical coherence tomography were obtained at each examination. RESULTS: Three eyes of three patients underwent pars plana vitrectomy for recurrent MF. Myopic foveoschisis recurrence occurred 6, 3.5, and 12 years after the primary vitrectomy, respectively. Repeat vitrectomy with staining and additional peeling of the internal limiting membrane resulted in good anatomical outcome and stabilization of visual acuity in all cases. CONCLUSION: Late recurrence of MF after successful primary vitrectomy is described. Fibrocellular proliferation on residual cortical vitreous or incomplete internal limiting membrane peeling during the initial vitrectomy may underlie recurrence

Stabilization of charge ordering in La_(1/3)Sr_(2/3)FeO_(3-d) by magnetic exchange

The magnetic exchange energies in charge ordered La_(1/3)Sr_(2/3)FeO_(3-d) (LSFO) and its parent compound LaFeO_(3) (LFO) have been determined by inelastic neutron scattering. In LSFO, the measured ratio of ferromagnetic exchange between Fe3+ - Fe5+ pairs (J_F) and antiferromagnetic exchange between Fe3+ - Fe3+ pairs (J_AF) fulfills the criterion for charge ordering driven by magnetic interactions (|J_F/J_AF| > 1). The 30% reduction of J_AF as compared to LFO indicates that doped holes are delocalized, and charge ordering occurs without a dominant influence from Coulomb interactions.Comment: 18 pages, 4 color figure

Quantum Optics with Surface Plasmons

We describe a technique that enables strong, coherent coupling between individual optical emitters and guided plasmon excitations in conducting nano-structures at optical frequencies. We show that under realistic conditions, optical emission can be almost entirely directed into the plasmon modes. As an example, we describe an application of this technique involving efficient generation of single photons on demand, in which the plasmon is efficiently out-coupled to a dielectric waveguide.Comment: 11 pages, 3 figure