Would the trachea collapse when you were exhaling if there were no rings of cartilage in its walls

The answer is YES. The trachea would collapse during exhaling due to the negative pressure developed as a result of evacuating air from the lungs. Physics dictates that the area with high pressure (outside environment) pressure on the region with low air pressure (in the lungs during exhalation).

format change of dna.  

the transfer of energy between two molecules spaced just nanometers apart plays a key role in many technologies, including photovoltaics, quantum information systems, lighting, and sensors, as well as in biophysics to measure nanometer distances and in photosynthesis. but an open question in this area is what effect, if any, the surrounding photonic environment has on this nanoscale energy transfer. by designing and performing a carefully controlled experiment to answer this question, scientists have settled the debate and found clues to improving the efficiency of many of the technologies that rely on this process.

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