Physics Projects Deflate for Lack of Helium-3

U.S. radiation detectors suck up the existing supply

3 min read

Earlier this year, a panicked U.S. congressional panel traded barbs about who was at fault for a sudden and surprising shortage of helium-3. The stable isotope is crucial in MRI lung research, low-temperature experimental physics, and—at the heart of the congressional dustup—in neutron detectors that can reveal smuggled nuclear materials. The United States has historically been the biggest global supplier of He-3, so the shortage there is affecting the entire world. In many countries, authorities are scrambling to find ways to procure more of the gas, stretch their remaining supplies, and find alternatives. But for some users, there are no substitutes.

He-3 is one neutron short of the two neutrons and two protons that make up its heavier cousin, the helium-4 of party balloons and silly voices. The lighter isotope is rare in nature, but it is a by-product of the decay of tritium (hydrogen-3) in thermonuclear weapons.

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Restoring Hearing With Beams of Light

Gene therapy and optoelectronics could radically upgrade hearing for millions of people

13 min read
A computer graphic shows a gray structure that’s curled like a snail’s shell. A big purple line runs through it. Many clusters of smaller red lines are scattered throughout the curled structure.

Human hearing depends on the cochlea, a snail-shaped structure in the inner ear. A new kind of cochlear implant for people with disabling hearing loss would use beams of light to stimulate the cochlear nerve.

Lakshay Khurana and Daniel Keppeler
Blue

There’s a popular misconception that cochlear implants restore natural hearing. In fact, these marvels of engineering give people a new kind of “electric hearing” that they must learn how to use.

Natural hearing results from vibrations hitting tiny structures called hair cells within the cochlea in the inner ear. A cochlear implant bypasses the damaged or dysfunctional parts of the ear and uses electrodes to directly stimulate the cochlear nerve, which sends signals to the brain. When my hearing-impaired patients have their cochlear implants turned on for the first time, they often report that voices sound flat and robotic and that background noises blur together and drown out voices. Although users can have many sessions with technicians to “tune” and adjust their implants’ settings to make sounds more pleasant and helpful, there’s a limit to what can be achieved with today’s technology.

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