Field of Science

Fixing broken voices and how polymers are coming to the rescue of our medical needs

A team at MIT has developed a polymer gel that can mimic human vocal cords. Although vocal cords don't make it to the news very often, they are a serious problem for millions of people around the world. They can be a problem for celebrities, too. Julie Andrews, who once had a rare, four-octave voice, lost the range after a vocal cord injury. I wrote about the polymer gel in The Economist this week.
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 Robert Langer, a biomedical engineer at MIT, proposes to inject the gel under the tissue membrane (a thin layer of cells that covers the vocal cords), forming an additional layer within... read more
Note: It's not what The Telegraph, who has happily jumped to the exaggeration bandwagon, would like you to believe. The gel isn't replacing scarred tissue. Instead, it is hoped that it will help restore flexibility in the vocal cords.

This is not the only innovation from Dr Langer’s lab that may make it into the human body. InVivo Therapeutics, an American medical devices company, with help from Dr Langer and his colleagues have developed a treatment for spinal cord injury. They use a scaffold made out of PLGA, a biodegradable polymer, to help patients recover from an injury that, if not dealt with properly, is infamous for causing paralysis. The scaffold is inserted at the point of the injury after removing dead tissue and is programmed to degrade within 21 days, the amount of time needed for the body to rebuild lost tissue. Although this treatment is not a cure either, the scaffold helps to make the most of the body’s repair systems. Work done on monkeys has shown that the technology works. This, too, will go into human trials next year, says Frank Reynolds, chief executive of the company.

Other work still in Dr Langer’s lab is looking at building intestinal, pancreatic and heart tissue using a range of materials. Touted as the next big frontier of medical technology, biomaterials are finally coming to the fore.

  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

Fish, schooling and video games

Much is said about why fish group together in schools. But there is little direct evidence for why that happens. Now, with the help of a video game, researchers know at least one reason why schooling is a good idea. I wrote about this in The Economist's Babbage blog.
Testing the theory 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... read more.
Dr Ioannou worked with Iain Couzin, an evolutionary biologist at Princeton University, who has been working for quite sometime on understanding collective animal behaviour. He speaks about his other work here and here. From the likes of it, it seems there is much we need to learn from animals.

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

Lenna at the highest resolution possible

Lenna, a 70s playboy girl
Among the many playboy girls there is one who is very famous in a geeky group of programmers. Her name is Lenna. And her image is used by the programmers to test their algorithms. Now researchers at Singapore's Agency for Science, Technology and Research have developed the smallest image of Lenna at the highest resolution that is permitted by the laws of Physics. I've written about in The Economist's Babbage blog.
Dr Kumar and his team start with a plate of silicon. The electron beam carves bits of this away, leaving a pattern of cylindrical posts each about 140 nanometres (billionths of a metre) across and 50 nanometres apart. That “about” is important, though. The exact diameters of the posts and the distances between them are crucial. Varying them changes the colour that forms between the posts... read more.
The colours are achieved by coating this plate with noble metals. This is not cheap, but they are already working on replacing them with cheaper metals or looking at the use of polymer. Furthermore, they want to use this technique for data storage.

Data on CDs, DVDs and Blu-Ray discs is stored in the form of 0s and 1s represented by pits and troughs on the disc's surface. With the new technique the pits and troughs will still be there in the form of cylindrical posts and spaces between them, but they will be able to reflect back light of a particular frequency. As this no longer limits them to a binary system, they could encode a whole string of 0s and 1s in just one "pit".

References for The Economist piece:
  1. Kumar et al., Nature Nanotechnology, 2012
  2. Lenna Image
  3. Retina Display Kumar K, Duan H, Hegde RS, Koh SC, Wei JN, & Yang JK (2012). Printing colour at the optical diffraction limit. Nature Nanotechnology PMID: 22886173

Oceanic carbon sinks

So nature deals with increasing carbon dioxide emissions by sucking up more of it. Plants take more and grow faster. The increased partial pressure of COcauses more of it to be absorbed by the oceans. On land more plants is a good thing, but in the oceans more COleads to increased acidity which can be devastating for the flora and fauna.

Recently there were two interesting papers, one in Nature and the other in Nature Geoscience, that looked at Earth's carbon sinks. I've written about the studies in The Economist's Babbage blog. I took the chance to speak to some of the leading researchers in the field: Ashley Ballantyne at the University of Colorado, Corinne Le Quéré at the University of East Anglia (and not involved in the climate scandal), Jean-Baptiste Sallée of the British Antarctic Survey and Jorge Sarmiento at Princeton University. The conversations helped me learn a number of things. I'm sharing those here:
  1. The ocean in the southern hemisphere take up most of the CO2 because of their large unbroken waters. But this absorbed gas is not evenly spread out. Some pockets have a lot more of it than others.
  2. This ocean also absorbs a lot of the heat that is getting trapped because of excess greenhouse gases. By one estimate almost 70% of it. As oceans warm up, their capacity to hold COreduces. These carbon sinks could become carbon sources at some point.
  3. The lack of an ozone layer leads to localised cooling in the Antarctic. Global warming causes most of the heating in the tropics. This temperature difference causes stronger winds which could whip up deeper ocean layers bringing up CO2-rich waters which won't be able to absorb as much of it as they do now.
  4. Land carbon sinks could become carbon sources, too. Increased temperature leads to growth of microbes in the soil. These will then consume more of organic matter and convert it into CO2, which they do already but the plant consumption of CO2 is able to keep that in check.
Climate change is a very complex phenomenon. I knew that but these conversations made me realise just how much we don't know (PS: this is not to doubt that humans are causing global warming). Only after a few questions, all researchers started answering the question by first saying 'We don't know, but one theory is...'. Oceanic carbon sinks, in particular, are a big area of debate, mostly because of the lack of hard data. Things are changing, but are they changing fasting enough?

A list of main references for The Economist piece:
  1. Ballantyne et al., Nature, 2012, 488, 70
  2. Salée et al., Nature Geoscience, 2012, ASAP
  3. Climate change: What lies beneath - The Economist
  4. Argo project, UK Met Office
  5. Climate Variability and Predictability (CLIVAR) Ballantyne AP, Alden CB, Miller JB, Tans PP, & White JW (2012). Increase in observed net carbon dioxide uptake by land and oceans during the past 50 years. Nature, 488 (7409), 70-2 PMID: 22859203

Sallée J-B, Matear RJ, Rintoul SR, & Lenton A (2012). Localized subduction of anthropogenic carbon dioxide in the Southern Hemisphere oceans. Nature Geoscience DOI: 10.1038/ngeo1523

Squirrels and climate change

Credit: Jeffrey Lane
Jan Murie, emeritus professor of biology at the University of Alberta in Canada, is passionate about squirrels. He has even written a book: The Biology of Ground-Dwelling Squirrels. Even after retiring he keeps up with his interest. With the lead author Jeffrey Lane, a biologist at the University of Edinburgh, he has published a paper in Nature on the effect of climate change on Columbian ground squirrels. I've written about it in The Economist's Babbage blog.

Here's the blurb:
Winter is a pain in the animal kingdom. Birds can flee it by migrating to warmer climes but grounded beasts, including mammals, have no choice but to stick around. To cope, many species have learned to hibernate. Some, like the Columbian ground squirrel, spend up to nine months of each year in their alcoves. This conserves energy but leaves them with only three months to plump up for the next winter and, crucially, to procreate. To make matters worse, climate change is leading them to emerge from hibernation later than usual... read more.
While chatting with him about the paper he told me that these squirrels in captivity live up to the age of 13 years, while in the wild their average is 6 years. Adult squirrels tend to cope well, but it's the juveniles that get hunted down. Although there's nothing surprising about that, it was a reminder of what can happen when you live in the wild. Especially, if you happen to be at the bottom of the food chain.

  1. Lane et al., Nature, 2012, ASAP  
  2. Lane et al., J. Evol. Biol., 2011, 1949 Lane JE, Kruuk LEB, Charmantier A, Murie JO, & Dobson FS (2012). Delayed phenology and reduced fitness associated with climate change in a wild hibernator Nature DOI: 10.1038/nature11335
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