Tag: economist

Repairing voices: Good vibrations

Akshat RathiLeave a comment

How to restore people’s voices

Injury, disease or sheer old age mean that as many as 7% of Americans (and, presumably, a similar proportion of the population of other countries) have some kind of voice disorder caused by scarring of their vocal cords. Such scarring makes the cords stiff, and stops them producing sound in the normal way. But that could be overcome if a method were found to restore the cords’ flexibility.

Robert Langer, a pioneering biomedical engineer at the Massachusetts Institute of Technology, and his colleagues think they have one. They have developed a material that mimics the characteristics of natural vocal cords and could thus help restore distorted voices.

To make their new material, Dr Langer and his team took polyethylene glycol, a substance widely used in the cosmetics industry and thus known to be safe, and altered the chemical linkages between its molecules. This allowed them to control the polymer’s viscosity and elasticity. After some trial and error, as they described on August 20th to a meeting of the American Chemical Society held in Philadelphia, they hit on a mixture which matches the traits of human vocal cords. Laboratory tests have shown that when air is blown through a model of the vocal cords made from this material, the model responds in the way that real cords do.

The new polymer gel is not intended to heal scarred tissue, but rather to make the whole tissue flexible enough to restore vibrations to normal. To achieve this Dr Langer proposes to inject the gel under the tissue membrane (a thin layer of cells that covers the vocal cords), forming an additional layer within. Patients with different voices could be treated with gels that had different physical characteristics, in order to produce the desired effect.

There is a limitation. The new gel is prone to degradation and in some cases would need to be topped up regularly. But trials on animals suggest the procedure is safe, and human trials are expected to start soon.

First published in The Economist.

References:

  1. A material to rejuvenate aging and diseased human vocal cords (Press release)
  2. Karajanagi et al, Annals of Otlogy, Rhinology and Laryngology, 2011
  3. InVivo therapeutics

A list of main references here. Image credit: The Economist

Animal Behaviour: The benefits of schooling

Akshat Rathi1 Comment

Nearly four-fifths of the 28,000 known species of fish swim in schools, harmoniously aligning their movements with others around them. Besides reducing drag for those not in the front of the pack, coming together makes it harder for a predator to single out just one prey; a mass change of direction by the entire school might act to confuse the attacker further.

That, at least, is the theory. The rub is that testing it requires manipulating the behaviour of real fish—trickier even than herding cats. Now, though, Christos Ioannou, from Bristol University, may have found a way around it. As the researchers report in Science, he and his colleagues have developed a video game for piscine predator to play.

They put their gamer, a hungry bluegill sunfish, into a tank and projected computer-generated prey on one of its walls. Each digital fish in the 16-strong school was programmed to maintain their speed and to move away to avoid collision if they get too close to each other. But each was also endowed with a mind of its own: some ignored what their neighbours did while others followed their every move.

It turns out that the real sunfish is indeed more likely to go after the lonely virtual minnows than the more gregarious ones. It seems, then, that there really is strength in numbers, though it be some time before Dr Ioannou manages to coax his bluegill into disclosing precisely why it prefers the loners.

Also published on economist.com.

Reference: Ioannou CC, Guttal V, & Couzin ID (2012). Predatory Fish Select for Coordinated Collective Motion in Virtual Prey. Science PMID: 22903520

Free image from stock.xchng.