| Description |
Physical properties can change when the scale that is being used to measure them changes. Small scales in particular are an area where properties can exhibit deviations from larger scaled measurements. Three experiments were performed in order to explore potential small-scale variations in measured physical properties. Two of the experiments focused on shortening the amount of time needed to acquire an image in magnetic resonance imaging (MRI), while the third experiment developed a new compressional model for use on nanoscale objects. The first two experiments focused on the topic of accelerated cardiac cine imaging using magnetic resonance. Previously developed acceleration techniques were prospectively validated, demonstrating an ability to acquire diagnostically useful images under challenging conditions such as real-time acquisition and rapid patient heart rates. Functional measurements derived from these images, such as left-ventricle ejection fraction, were very accurate when compared to standard methods of determining these physical properties. The second experiment developed the acceleration techniques used in the first experiment even further, showing promising results with 12-fold accelerated real-time imaging. The third experiment explored the measurement of elastic properties in nanoscale sized objects. The existing Hertz model of contact mechanics was shown to be insufficient for the accurate determination of elastic properties, and a new model was iv developed. This developed model was tested against two other models, and showed an excellent ability to predict real-world force and displacement values on nanoscale crystals. Furthermore, a previously unknown relationship between elastic properties and the breaking points of these crystals was discovered, potentially opening up a method for the nondestructive determination of a nanocrystal's structural limitations. |
