Use of a hyperbolic grid generation scheme in simulating supersonic viscous flow about three-dimensional winged configuration

The present paper describes a numerical mesh generation technique to be used with an implicit finite difference method for simulating visous supersonic flow about low-aspect-ratio wing body configurations using a single grid strategy. The computational domain is segmented into multiple regions, with borders located in supersonic areas to avoid the otherwise costly interfacing procedure between adjacent segments. The numerical procedure is applied to calculate the turbulent flow around the shuttle orbiter and a canard projectile at supersonic free stream Mach number

Superlinear Increase of Photocurrent due to Stimulated Scattering into a Polariton Condensate

We show that when a monopolar current is passed through an n-i-n structure, superlinear photocurrent response occurs when there is a polariton condensate. This is in sharp contrast to the previously observed behavior for a standard semiconductor laser. Theoretical modeling shows that this is due to a stimulated exciton-exciton scattering process in which one exciton relaxes into the condensate, while another one dissociates into an electron-hole pair.Comment: 17 pages with 10 figure

Geodynamo and mantle convection simulations on the Earth Simulator using the Yin-Yang grid

We have developed finite difference codes based on the Yin-Yang grid for the geodynamo simulation and the mantle convection simulation. The Yin-Yang grid is a kind of spherical overset grid that is composed of two identical component grids. The intrinsic simplicity of the mesh configuration of the Yin-Yang grid enables us to develop highly optimized simulation codes on massively parallel supercomputers. The Yin-Yang geodynamo code has achieved 15.2 Tflops with 4096 processors on the Earth Simulator. This represents 46% of the theoretical peak performance. The Yin-Yang mantle code has enabled us to carry out mantle convection simulations in realistic regimes with a Rayleigh number of $10^7$ including strongly temperature-dependent viscosity with spatial contrast up to $10^6$.Comment: Plenary talk at SciDAC 200

Unforgeable Noise-Tolerant Quantum Tokens

The realization of devices which harness the laws of quantum mechanics represents an exciting challenge at the interface of modern technology and fundamental science. An exemplary paragon of the power of such quantum primitives is the concept of "quantum money". A dishonest holder of a quantum bank-note will invariably fail in any forging attempts; indeed, under assumptions of ideal measurements and decoherence-free memories such security is guaranteed by the no-cloning theorem. In any practical situation, however, noise, decoherence and operational imperfections abound. Thus, the development of secure "quantum money"-type primitives capable of tolerating realistic infidelities is of both practical and fundamental importance. Here, we propose a novel class of such protocols and demonstrate their tolerance to noise; moreover, we prove their rigorous security by determining tight fidelity thresholds. Our proposed protocols require only the ability to prepare, store and measure single qubit quantum memories, making their experimental realization accessible with current technologies.Comment: 18 pages, 5 figure

Simultaneous sub-second hyperpolarization of the nuclear and electron spins of phosphorus in silicon

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.Comment: 4 pages, 3 figure

Peer-to-Peer and Mass Communication Effect on Revolution Dynamics

Revolution dynamics is studied through a minimal Ising model with three main influences (fields): personal conservatism (power-law distributed), inter-personal and group pressure, and a global field incorporating peer-to-peer and mass communications, which is generated bottom-up from the revolutionary faction. A rich phase diagram appears separating possible terminal stages of the revolution, characterizing failure phases by the features of the individuals who had joined the revolution. An exhaustive solution of the model is produced, allowing predictions to be made on the revolution's outcome

Clinical outcomes after reverse shoulder arthroplasty in patients 60 years old and younger; Medium-term results

BACKGROUND: Reverse total shoulder arthroplasty (RTSA) has been well-described as a surgical solution to manage rotator cuff tear arthropathy in elderly, low demand paitents. As experience has increased along with improvements in technique and implant design, RTSA has become increasingly used to manage more varied pathologic conditions of the shoulder in younger, more active patients. This study evaluates outcomes in a consecutive series of patients aged 60 years old and younger after undergoing RTSA. METHODS: There were 94 shoulders in 89 patients enrolled. Mean age of the cohort was 54.8 (range 18-60 years). Surgical indications included rotator cuff tear arthropathy, irreparable rotator cuff tear without arthritis, glenohumeral arthritis with erosive glenoid deformity, inflammatory arthropathy, proximal humerus fracture nonunion/malunion and failed prior shoulder arthroplasty. Sixty-one shoulders (70%) had undergone at least one prior surgery. Of these, 6 shoulders (6% of total cohort) had a prior failed arthroplasty. Clinical outcomes (American Shoulder and Elbow Surgeons score, Western Ontario Osteoarthritis of the Shoulder index; visual analog scale pain), radiographic outcomes and complications were analyzed and assessed for correlation with patient demographic factors. RESULTS: The mean follow-up for this cohort was 4.9 years (range 2-12 years). Subjects experienced improvements in ASES score and pain ( CONCLUSION: With medium-term follow-up, RTSA is a reliable and predictable operation to manage various pathologic conditions in patients aged 60 years or less. Patients predictably experience significant improvements in pain and range of motion while assuming a modest complication risk. Long-term study is needed to understand potential for late complications or implant failure