Hello everyone, We had a huge turnout at the SUMS Relay on Wednesday. Thanks to all 9 teams who turned up, in particular teams Tachyon and Scroteam who notified us beforehand that they were coming, cheers. Congratulations once again goes to Team Vasak and Geoff Bailey (i.e. Team Geoff), for coming equal first answering all of the questions. Top effort. Next week (i.e. Wednesday October 14), Duncan Sutherland will be giving his 2008 honours talk about microbubble contrast agents. Don’t worry, it’s an applied talk so kindergarten students can understand it. Duncan was kind enough to provide an abstract: Traditional medical ultrasonography has used the backscattering of acoustic signals from tissue to investigate an object of interest. Microbubble contrast agents, which are typically administered intravenously into a patient’s circulatory system, were first approved for clinical studies in 1991. Modern contrast agents are typically a gas filled microbubble, which may be preformed with a shell of, for example, lipid, polymer or albumin. Contrast agents enhance backscatter, due to the high compressibility of the gas, relative to body tissue. The oscillatory response of the microbubble to an applied ultrasound field is complicated and frequency dependent. The bubble has a size dependent linear resonance frequency. Typically the contrast agent size is 1-7 um with resonant frequencies in the 2-15 MHz range, which is used for clinical applications. As the amplitude of the driving field is increased, the bubble response is nonlinear, which leads to sub and higher harmonic generation. New techniques have been developed for use in specialised applications to utilise this phenomenon. I will be discussing the some of the models that have been developed to describe the response of a single bubble to a driving pressure. This requires consideration of the surrounding fluid, internal gas and the shell layer of the microbubble. The discussion will focus on a second order ODE, called the Rayleigh-Plesset (RP) equation. The RP equation may be extended to include effects due to fluid viscosity and surface tension. Similarly, it is possible to include damping of the bubble oscillation due to radiation at the bubble wall. For contrast agents with encapsulating shells the equation of motion, due to Church, of the bubble wall is, again, an extension of the RP equation. Some simulation results will be presented, and limitations of the models will be discussed. Talk: Models of Ultrasound Contrast Agents Speaker: Duncan Sutherland Location: Carslaw 350 Date/Time: October 14th, 1-2pm Hope to see you there for the last SUMS talk of the year. Meanwhile SUMS is also planning concerts for week 13 (Wednesday evening and Friday lunchtime), if you would like to perform in either or both SUMS concerts, please email usydmaths@gmail.com