We have tested the applicability of the global modal approach in the density wave theory of spiral structure for a sample of six spiral galaxies: NGC 488, NGC 628, NGC 1566, NGC 2985, NGC 3938 and NGC 6503. The galaxies demonstrate a variety of spiral patterns from the regular open and tightly wound spiral patterns to a multi-armed spiral structure. Using the observed radial distributions of th...

PURPOSE To quantitatively assess the performance and reproducibility of 3D spiral coronary artery wall imaging with beat-to-beat respiratory-motion-correction (B2B-RMC) compared to navigator gated 2D spiral and turbo-spin-echo (TSE) acquisitions. MATERIALS AND METHODS High-resolution (0.7 × 0.7 mm) cross-sectional right coronary wall acquisitions were performed in 10 subjects using four techn...

AIM The aim of this study was evaluation of constructive alignment of student perceptions to a spiral curriculum, as a pre-requisite to successful learning. METHOD A survey was undertaken to evaluate student thoughts and experiences of a spiral curriculum, by participation in an anonymous voluntary questionnaire. Students were asked to rate their thoughts on their understanding, perceived ben...

T he first observations that placental bed defects were potentially linked to clinical outcomes such as pre-eclampsia (PE) were made nearly 50 years ago. 1 This study followed prior findings that the placental clearance of radio-labeled saline was significantly decreased in women with hypertensive gestations. 2 Histological examination of pla-centas and placental bed biopsies obtained from comp...

cardiac myocytes under physiological conditions, are described as planar waves traveling along the longitudinal cell axis [1]. Other patterns of Ca wave propagation – circular or spiral Ca waves [2, 3] – have been observed in physiological conditions as well. Lipp & Niggli, 1993 [2], Ishida et al., 1999 [3] and Engel et al., 1994 [4] have described spiral calcium waves as individual events. We ...

Rotating spiral waves have been observed in numerous biological and physical systems. These spiral waves can be stationary, meander, or even degenerate into multiple unstable rotating waves. The spatiotemporal behavior of spiral waves has been extensively quantified by tracking spiral wave tip trajectories. However, the precise methodology of identifying the spiral wave tip and its influence on...

Spiral-in/out functional magnetic resonance imaging (fMRI) methods acquire one image before the echo time (TE) and a second image after TE during each scan. Weighted combination of the two images provides a time series with reduced susceptibility dropout in frontal and medial temporal regions as well as increased signal-to-noise ratio (SNR) in regions of uniform cortex. In this study, task acti...

Purpose: Commonly used diffusion weighted (DW) imaging such as DW spin echo (SE) type echo planar imaging (DW-SE-EPI) is known to be a snapshot-like acquisition and to have a relatively high signal-to-noise ratio. Spiral MRI sequence (SPIRAL) has characteristics similar to these of EPI, but it has rarely been used for diffusion-weighted imaging (DWI). In vivo DW-SPIRAL of the rat brain has almo...