Physics Essays and Research Papers
Paraphrasing for all the answering of tutorial question
6. In a 3T MRI system that has just been passively shimmed, the variation of the resonance frequency of a small spherical sample filled with water varies from 150 Hz to 300 Hz over the surface of a sphere of diameter 45cm. What is this variation in parts per million (ppm)? Is such a variation reasonable?
Since 1ppm in a 1T MRI system is approximately 42.57 MHz/T
3T system = 127.7 Hz
Variation at 150 Hz is 150/127.7= 1.17ppm
Variation at 300 Hz is 300/127.7= 2.35ppm
Therefore, the variation is…Read Text
MRES 7005 _Fast Imaging Techniques (EPI >Echo planar Imaging)
EPI compared to conventional fast imaging methods:
EPI uses the Blip EP method of phase encoding where each phase blip between echoes causes a shift in k-space line. Each k-space line is contributed by the gradient refocused echo and is either read positively or negatively through the gradient change. The quickly switching gradients that produce the echo train are responsible for the odd and even echoes. When the lines are read, the reversed read lines are reordered before constructing the…Read Text
Are there any geological analogues for current climate change
Hyperthermal events lead to complete alteration of different weather patterns which influenced a lot in the distribution of the animals across the world (Seki, 2010).
The Paleocene-Eocene Thermal Maximum (PETM) was a duration in which natural increase in atmospheric temperatures occurred because of rapid release of carbon dioxide gas into the atmosphere. The Paleocene-Eocene Thermal Maximum occurred around fifty-five years ago. The hyperthermal event took place when the carbon II oxide…Read Text