There is evidence that spiral waves and their breakup underlie mechanisms related to a wide spectrum of phenomena ranging from spatially extended chemical reactions to fatal cardiac arrhythmias [A. T. Winfree, The Geometry of Biological Time (Springer-Verlag, New York, 2001); J. Schutze, O. Steinbock, and S. C. Muller, Nature 356, 45 (1992); S. Sawai, P. A. Thomason, and E. C. Cox, Nature 433, ...

We describe a Fourier-based method of separating bars from spirals in near-infrared images. The method takes advantage of the fact that a bar is typically a feature with a relatively fixed position angle and uses the simple assumption that the relative Fourier amplitudes due to the bar decline with radius past a maximum in the same or a similar manner as they rose to that maximum. With such an ...

Meandering of a one-armed spiral tip has been noted in chemical reactions and numerical simulations. Barkley, Kness, and Tuckerman show that meandering can begin by Hopf bifurcation from a rigidly rotating spiral wave (a point that is verified in a B-Z reaction by Li, Ouyang, Petrov, and Swinney). At the codimension-two point where (in an appropriate sense) the frequency at Hopf bifurcation equ...

We validated 3D radiochromic film dosimetry for volumetric modulated arc therapy (VMAT) using a newly developed spiral water phantom. The phantom consists of a main body and an insert box, each of which has an acrylic wall thickness of 3 mm and is filled with water. The insert box includes a spiral film box used for dose-distribution measurement, and a film holder for positioning a radiochromic...

PURPOSE To determine whether spiral CT angiography allows accurate, quantitative evaluation of anatomic abnormalities, including detection of additional lesions, delineation of plaque morphology, and estimation of degree of internal carotid artery stenosis. METHODS Spiral CT angiography with a maximum intensity projection technique was compared with selective digital subtraction angiography (...

Sturgeon is one of the most important species of the Caspian Sea aquatics. Unfortunately, this species faces the threat of extinction today. This makes specific studies on any type of sturgeons more important than before. Studies like histological studies, radiology, and sonography, all require a complete understanding of the anatomy of this fish. Since pilot studies showed some misconceptions ...

Manufactured single crystal components using Ni-base super alloys are routinely used in the hot sections of aero engines and industrial gas turbines due to their outstanding high temperature strength, toughness and resistance to degradation in corrosive and oxidative environments. To control the quality of the single crystal turbine blades, particular attention has been paid to grain selection,...

The Large Eddy Simulation (LES) technique with the Smagorinsky-Lilly dynamic subgrid model and two-equation Standard k-ω Transitional turbulence model are applied to investigate non-spiral and spiral blood flow through three dimensional models of arterial stenosis and aneurysm. A spiral pattern of blood flow is thought to have many beneficial effects on hemodynamics. Previous computational stud...

SPIRAL generates automatically high quality implementations for a variety of DSP signal transforms. The generated code is adapted to the machine configuration and architecture. SPIRAL achieves this through an intelligent search in the Cartesian product of the space of algorithms and the space of coding variants. This paper describes the mathematical framework that SPIRAL uses to represent, gene...