نتایج جستجو برای: spiral
تعداد نتایج: 32206 فیلتر نتایج به سال:
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...
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...
Particulate separation has many applications in medicine, biology and industry. In this research, the separation of polystyrene particles with a diameter of 10, 20 and 30 μm in the fluid flow of a microchannel is investigated. The microchannel consists of a spiral region and a straight region under the influence of acoustic waves. In the spiral region, the particles under hydrodynamic effects u...
The effect of the beta-lactam antibiotic cephalexin on the spiral conformation of cells of Aquaspirillum spp. was examined by scanning electron microscopy. A. itersonii and A. peregrinum, which are known to have a left-handed spiral shape, elongated and still showed left-handed spirals in medium containing cephalexin. The spiral conformation of the elongated cells is therefore considered to rep...
The effect of a long length scale static inhomogeneity on spiral wave dynamics is studied in the two-dimensional complex Ginzburg-Landau equation. We find that the inhomogeneity leads to the formation of a dominant spiral domain that suppresses other spiral domains, and that the spiral vortices slowly drift in the presence of an inhomogeneity with a velocity that is proportional to the local pa...
Spiral Architecture is a relatively new and powerful approach to general purpose machine vision system. On this novel architecture, image rotation is achieved by Spiral Multiplication. However, the general image rotation on Spiral Architecture has two effects. One is scaling segmentation and the other is rotation. This paper presents an algorithm to achieve image rotation without scaling on Spi...
The influence of circularly polarized electric fields (CPEFs) on the stability of multiarmed spiral waves is investigated. It is shown that CPEFs can change the period of the multiarmed spirals. The average period is an important quantity of multiarmed spiral and it must be larger than a threshold for stable multiarmed spiral. After a counter-rotating CPEF with suitable amplitude and period is ...
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