John Dabiri and Kakani Katija Link Tiny Sea Creatures to Large-scale Ocean Mixing
John Dabiri, Assistant Professor of Aeronautics and Bioengineering, and graduate student Kakani Katija have discovered a new mechanism that explains how some of the ocean's tiniest swimming animals can have a huge impact on large-scale ocean mixing. Dabiri describes, "we've been studying swimming animals for quite some time, the perspective we usually take is that of how the ocean—by its currents, temperature, and chemistry—is affecting the animals. But there have been increasing suggestions that the inverse is also important—how the animals themselves, via swimming, might impact the ocean environment." Ares Rosakis, the Theodore von Kármán Professor of Aeronautics and Mechanical Engineering and chair of the EAS Division described the research as, "truly reflective of the type of exciting, without-boundaries research at which Caltech engineering professors excel." [Caltech Press Release]
Morteza Gharib and Abbas Nasiraei Moghaddam Show Function of Helical Band in Heart
Using an MRI technique, Morteza Gharib, Hans W. Liepmann Professor of Aeronautics and Professor of Bioengineering, and his colleague Abbas Nasiraei Moghaddam, a Caltech graduate and visitor in Bioengineering, were able to create some of the first dynamic images of normal heart muscle in action at the tissue level. They showed that a muscular band--which wraps around the inner chambers of the heart in a helix--is actually a sort of twisting highway along which each contraction of the heart travels. "We tagged and traced small tissue elements in the heart, and looked at them in space, so we could see how they moved when the heart contracts," Gharib explains. "In this way, we were able to see where the maximum physical contraction occurs in the heart and when--and to show that it follows this intriguing helical loop."