Several members of our research group were supposed to give talksa the 79th Meeting of the Mississippi Academy of Sciences on February 26th, however the trip was derailed by dangerous road conditions due to inclement weather.
Two grad students (Sunethra Dayavansha and Nazanin Omidi) and I gave a colloquium talk at Rhodes College in Memphis (here's our crazy selfie).
After the talk, we stopped by an SPS meeting (of course free pizza, it's SPS!). Rhodes has an incredible SPS group. They've received outstanding chapter awards for at least the last 10 years running! Then we saw a very cool demo where they supercooled some beer (Corona to be exact) and then by tapping the beer on the lab benchtop, the freezing process was initiated. It was a fun trip.
Charles C. Church, Cecille Labuda and Kathryn Nightingale. A Theoretical Study of Inertial Cavitation from Acoustic Radiation Force Impulse Imaging and Implications for the Mechanical Index. Ultrasound Med Biol; 41(2) 2015. http://dx.doi.org/10.1016/j.ultrasmedbio.2014.09.012
Abstract. The mechanical index (MI) attempts to quantify the likelihood that exposure to diagnostic ultrasound will produce an adverse biological effect by a non-thermal mechanism. The current formulation of the MI implicitly assumes that the acoustic field is generated using the short pulse durations appropriate to B-mode imaging. However, acoustic radiation force impulse (ARFI) imaging employs high-intensity pulses up to several hundred acoustic periods long. The effect of increased pulse durations on the thresholds for inertial cavitation was studied computationally in water, urine, blood, cardiac and skeletal muscle, brain, kidney, liver and skin. The results indicate that, although the effect of pulse duration on cavitation thresholds in the three liquids can be considerable, reducing them by, for example, 6%–24% at 1 MHz, the effect on tissue is minor. More importantly, the frequency dependence of the MI appears to be unnecessarily conservative; that is, the magnitude of the exponent on frequency could be increased to 0.75. Comparison of these theoretical results with experimental measurements suggests that some tissues do not contain the pre-existing, optimally sized bubbles assumed for the MI. This means that in these tissues, the MI is not necessarily a strong predictor of the probability of an adverse biological effect.