Good vibes regrow teeth

    A nifty gadget promises to give gap-toothed hockey and rugby players a healthy new smile. It's an ultrasound transmitter that fits neatly inside a person's mouth like a brace and could help to regrow damaged teeth.

Jie Chen and Ying Tsui, engineers at the University of Alberta in Canada, developed the miniature device after ultrasound stimulation encouraged damaged teeth and jawbone tissue to regrow in animals.

Tarek El-Bialy, who works in Alberta's medical faculty, was able to regrow teeth in rabbits with a larger device, but only when some tooth root remained in place.

The ultrasound device could help those who have had their teeth broken while playing high impact sports such as ice hockey and rugby. The tooth brace sends low-power ultrasound pulses to the damaged tooth over many months. A piezoelectric crystal generates the ultrasound by vibrating at frequencies above 20 kilohertz when fed an alternating voltage from an oscillator charged by a battery.

Physiotherapists often use ultrasound to help broken bones knit back together, although the healing mechanism is not precisely understood. One theory is that pressure waves mimic the effect of strenuous exercise, loading a bone and tricking it into generating more bone cells - a process called osteogenesis. El-Bialy's work on rabbits in 2003 (American Journal of Orthodontics and Dentofacial Orthopedics, vol 124, p 427) first showed that low-power ultrasound also encourages growth of dental tissue.

Source: New Scientist

Giant parasol might help see past light pollution

Astronomers could soon be using a gigantic space-parasol to block out starlight that interferes with the view of planets in other solar systems. The daisy-shaped space shield could be used in conjunction with an orbiting telescope get clear images of the more than 175 planets that have been discovered orbiting other stars, say the authors of a University of Colorado at Boulder (CU) study, just published in Nature.

Made of thin plastic, the "starshade" would allow a telescope trailing thousands of miles behind it to image light from distant planets skimming by the giant petals without being swamped by light from the parent stars, explained CU's Professor Webster Cash. This would allow astronomers to then identify planetary features like oceans, continents, polar caps and cloud banks and even detect biomarkers like methane, oxygen and water if they exist.

"We think this is a compelling concept, particularly because it can be built today with existing technology," said Cash. "We will be able to study Earth-like planets tens of trillions of miles away and chemically analyze their atmospheres for signs of life."

It's envisaged that the telescope and starshade - dubbed the New Worlds Imager - would be launched together into an orbit roughly 1 million miles from Earth. The starshade would then be unfurled and small thrusters would move it into the lines of sight of nearby stars thought to harbor planets. The thrusters would be intermittently turned on to hold the starshade steady during the observations of the planets, which would appear as bright specks. The paper includes solutions to optical challenges like the bending and scattering of light between the pliable, 50-yard-in-diameter starshade and the space telescope, which would orbit in tandem roughly 15,000 miles apart.

Other proposals for imaging distant planets involve suppressing parent starlight once it has entered the telescope - an enormously complicated exercise. "In contrast, this is a very clean and simple optical concept, and may be the most promising idea yet on how to directly image our Earth-like neighbors," said Marc Kuchner, of NASA's Goddard Space Flight Center's Exoplanets and Stellar Astrophysics Laboratory.

An even more advanced version of the imaging system might involve a ring of telescopes placed on the moon beneath a fleet of orbiting starshades that would allow scientists to actually photograph distant, Earth-like planets, Cash speculated. "There is a bit of Buck Rogers in the New Worlds Imager concept, but seeking and mapping new lands is something that seems to ring deep in the human psyche."

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