03/09/2016 Nazanin Omidi to give a talk at ASA 171 in Salt Lake City.

Nazanin Omidi will give a talk at the 171st Acoustical Society of America meeting in Salt Lake City Utah.  The meeting will be this upcoming May 2016. 

Nazanin Omidi, Cecille Labuda, Charles C. Church.  Computation of Ultrasonic Pressure Fields in Feline Brain​.

In 1975, Dunn et al. (JASA 58:512-514) showed that a simple relation describes the ultrasonic threshold for cavitation–induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during experimental exposures rather than estimating them using linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) at increasing values of the source pressure at frequencies of 1, 3, and 9 MHz. The corresponding focal intensities were correlated with the experimental data of Dunn et al. The focal pressure waveforms were also computed at the location of the true maximum. For low source pressures, the computed waveforms were the same as those determined using linear theory, and the focal intensities matched experimentally determined values. For higher source pressures, the focal pressure waveforms became increasingly distorted; similar results were obtained with increasing frequency.

03/03/2016 Joel Mobley to give Science Cafe on the physics of MRI.

Joel Mobley will give a Science Cafe on March 22 on the physics of magnetic resonance imaging.  The Science Cafe will be held at Lusa Bakery Bistro and Bar, 1120 North Lamar Blvd, Oxford.  The Oxford Science Cafe website can be found here: http://www.phy.olemiss.edu/oxfordsciencecafe/

Abstract

Magnetic Resonance Imaging (MRI) has revolutionized the diagnosis and treatment of a broad spectrum of medical conditions. Since its clinical debut in the 1980’s, it has evolved to provide a level of anatomical detail not possible with any other imaging modality, all without the focus of an ultrasound probe or the directionality of an x-ray beam. The fundamental principles at work in MRI include quantum physics, spinning tops, flipping magnets and simple patterns of bright and dark. The aim of this talk is to remove some of the mystery of how the manipulation of the weakest magnets in the atom leads to the MR image and to look at emerging medical treatments enabled by MRI.

02/25/2016 Sunethra Dayavansha, Ukesh Koju and Kevin Lin to give talks in the PGSA symposium.

Three of our graduate students will give talks in the University of Mississippi Physics Graduate Student Association (PGSA) Symposium to be held this Saturday February 27.  Ukesh is one of the main organizers of the symposium.  The talks are described below.

  • Sunethra Dayansha et al.  Temperature Dependence of Shear Wave Speed in a Viscoelastic Micellar Fluid.
  • Ukesh Koju et al. Propagation of Pulsed Ultrasonic Fields in a Band Gap of a Two Dimensional Phononic Crystal.
  • Kevin Lin et al.  Multimodal Nondestructive Dry Cask Basket Structure and Spent-Fuel Evaluation - Initial Stage Simulation.

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