January 11, 2013
We’re all familiar with the concept of a breathalyzer—a device that indicates someone’s blood alcohol content by precisely analyzing his or her breath. Because the breakdown of alcohol produces predictable quantities of various gases, these machines are reliable enough to be used by law enforcement to declare a driver, say, as legally intoxicated.
Recently, a group of researchers from the University of Vermont saw this idea and had another: What if a device could be designed to detect a chemical signature that indicates a bacterial infection in someone’s lungs? Their result, revealed yesterday in the Journal of Breath Research, is a quick and simple breath test—so far used only with mice—that can diagnose infections such as tuberculosis.
In their study, they focused on analyzing volatile organic compounds (VOCs) in mouse breath to distinguish between different strains of bacteria that were infecting the animals’ lungs. They hypothesized that these bacteria produce VOCs not normally present in the lungs, thus allowing their test to differentiate between a healthy animal and a sick one.
Initially, a number of the mice were infected with either Pseudomonas aeruginosa or Staphylococcus aureus—both common types of bacteria in either acute and chronic lung infections—and their breath was tested 24 hours later. The researchers used a technique called “secondary electrospray ionization mass spectrometry” (a name that, admittedly, requires quite a mouthful of expelled air), which can detect VOC quantities of as little as a few parts per trillion.
Their test was a success: There was a significant difference between the chemical signatures of healthy and infected mouse breath, and their test was even able to indicate which type of bacteria were the source of the infection.
Although the concept has only been used on mice so far, the researchers think that you could someday be blowing into a bacterial breathalyzer as part of your routine medical exam. Their prediction stems from the fact that the approach offers several advantages over conventional ways of detecting bacterial infections in the lungs.
“Traditional methods employed to diagnose bacterial infections of the lung require the collection of a sample that is then used to grow bacteria,” said Jane Hill, one of the paper’s co-authors, in a statement. “The isolated colony of bacteria is then biochemically tested to classify it and to see how resistant it is to antibiotics.”
This process can take days and sometimes even weeks just to identify the type of bacteria. By contrast, she said, “Breath analysis would reduce the time-to-diagnosis to just minutes.”
This type of test would also be less invasive than current methods. Thus, for patients suffering from bacterial infections…a breath of fresh air.
January 10, 2013
Another one of the products of science that seem too amazing to be true: Researchers at MIT have invented the technological equivalent of Mexican jumping beans. As seen in the video above, they’ve created polymer films that act like artificial fast-twitch muscles, spontaneously curling up and dancing around in an eerily life-like way.
The polymer sheets are specially designed to rapidly expand when they come into contact with water, and contract when they expel it. Thus, by placing the sheets on a slightly moist surface, Mingming Ma and colleagues were able to make them dance around completely on their own. They published the details of their invention today in a paper in Science.
Although the polymers are simply pretty cool to watch, the researchers had a practical application in mind when they developed them: producing electricity. When they covered the sheets with a piezoelectric polymer that generates electricity from pressure and stress (30 seconds into the video), and wired it to a capacitor, they were able to store minute amounts of energy expelled by all that folding and flipping.
They say the sheets produced bursts of electricity peaking at about 1 volt. Since the polymer can also be stimulated by the mere presence of water vapor in the air—and not just water on a table—they speculate that these types of thin water-powered sheets could someday be harnessed to provide electricity for small ubiquitous objects, like environmental sensors.
“With a sensor powered by a battery, you have to replace it periodically,” lead author Ma said in a statement. “If you have this device, you can harvest energy from the environment so you don’t have to replace it very often.”
It’s even possible, they suggest, that this type of material could be sewn into clothing, in order to harvest electricity from the sweat that evaporates off your body. ”You could be running or exercising and generating power,” said Liang Guo, a co-author.
The sheets are made from a pair of polymers: one called polypyrrole, which serves as a rigid supporting matrix, and another called polyol-borate, a flexible gel substance woven throughout that does the expanding and contracting when in contact with water. The researchers were inspired by the configuration of animal muscles (including our own), which are made from a rigid network of collagen fibers woven with elastic microfibrils.
In the video above, when the superthin film comes in contact with minute amounts of moisture, the bottom layer absorbs water and quickly curls upward. Then, once the bottom is lifted off the table and comes into contact with the air, the moisture evaporates off of it, and it flattens back out.
The team even tested the strength of this fascinating polymer construction, using clamps and heavy objects, to see just how much weight the polymer sheets could lift when stimulated. They found that a 25-milligram piece of film could lift a stack of glass slides 380 times heavier than itself and produce up to 27 megapascals of pressure—80 times more than the amount of pressure generated by typical mammalian muscle. Pretty amazing for a paper-thin sheet of film.
Whenever anyone talks about ocean acidification, they discuss vanishing corals and other shelled organisms. But these aren’t the only organisms affected—the organisms that interact with these vulnerable species will also change along with them.
These changes won’t necessarily be for the good of the shell and skeleton builders. New research published in Marine Biology shows that boring sponges eroded scallop shells twice as fast under the more acidic conditions projected for the year 2100. This makes bad news for the scallops even worse: not only will they have to cope with weakened shells from acidification alone, but their shells will crumble even more quickly after their cohabiters move in.
Boring sponges aren’t named thus because they’re mundane; rather, they make their homes by boring holes into the calcium carbonate shells and skeletons of animals like scallops, oysters and corals. Using chemicals, they etch into the shell and then mechanically wash away the tiny shell chips, slowly spreading holes within the skeleton or shell and sometimes across its surface. Eventually, these holes and tunnels can kill their host, but the sponge will continue to live there until the entire shell has eroded away.
Alan Duckworth of the Australian Institute of Marine Science and Bradley Peterson of Stony Brook University in New York brought boring sponges (Cliona celata) and scallops (Argopecten irradians) into the lab to examine the effects of temperature and acidity (measured through pH) on drilling behavior. They set up a series of saltwater tanks to compare how much damage sponges did to scallops under current temperature and ocean conditions (26°C and pH 8.1), projected conditions for 2100 (31°C and pH 7.8), and each 2100 treatment alone (31°C or pH 7.8).
Under higher acidity (lower pH), boring sponges drilled into scallop shells twice as fast, boring twice as many holes and removing twice as much shell over the course of the 133-day study. The lower pH alone weakened the shells, but after the boring sponges did their work, the scallop shells were an additional 28% weaker, making them more vulnerable to predation and collapse from the sponges’ structural damage.
The sponges weren’t entirely thrilled by the water’s higher acidity, which killed 20% of the them (although the researchers aren’t sure why). Despite this loss, 80% of the sponges doing twice as much drilling meant more damage to shelled organisms in total. Temperature did not affect sponge behavior at all.
This study illustrates a classic positive feedback loop, where weakness in the shells leads to more weakness. And not through the sponge-drilled holes alone: the addition of sponge-drilled holes creates more surface area for acidification to further erode the shells, hastening each scallop’s inevitable collapse. It’s tempting to speculate out to the rest of the system—that the sponges are destroying their own habitat more quickly than scallops can produce it—but we don’t really know whether in the long run this is also bad news for the sponges.
Though a small and specific example, this study illustrates how a seemingly small change—more acid and weaker shells—can ripple out and affect other organisms and the rest of the ecosystem.
January 9, 2013
El Niño, the climate pattern that increases Pacific Ocean surface temperatures every three to seven years, has long been known to pummel the Sierra Nevada with snow, limit Peruvian anchovy fishermen’s harvest and bless the Hawaiian Islands with dry, beach-friendly weather. The question of whether the effects of El Niño have become more extreme in recent decades, as climate change has intensified, hasn’t accrued a consensus among scientists. But now, new research released last week, sponsored by the National Science Foundation and published in Science, strengthens the link between El Niño activity and climate change.
During an El Niño season (the next one has been delayed, but is expected to begin later this year) the force of trade winds in the western and central Pacific diminishes or even reverses, causing a spike in surface water temperatures. As the slackened winds allow–or the reversed winds slowly push–the warmer water east across the ocean, rainfall follows it.
El Niño and its cold-water counterpart La Niña, which occurs between El Niño episodes when the regular trade winds intensify their westward push, have global ramifications. Wildfires in Australia and famines in India have been associated with the climate pattern. The cycle of El Niño and La Niña also appears to have intensified in recent years. Searching for reasons why, scientists debated a link with climate change as long ago as 1997, when researchers at the National Center for Atmospheric Research published a study titled “El Niño and Climate Change.” They couldn’t identify a clear connection, but they believed there was an unidentified force at work–one that required further investigation. “[A]t least part of what is happening… can not be accounted for solely by natural variability,” they wrote.
A year later, experts at the Nevada-based Western Regional Climate Center, which disseminates climate data and conducts research, also contemplated whether global warming was goosing El Niño. They were more overtly suspicious of a linkage, but again, lacked specific evidence. In a post on the center’s website, they noted:
It is plausible that a warmer earth would produce more and stronger El Niños. There is some evidence that the earth has warmed over the past two decades, and there is no doubt that El Niño has been much more frequent in that time. If the evidence of a warming earth is taken at face value (not universally accepted), there still remains a wide spectrum of opinions on whether we are seeing a manifestation of human modification of global climate, or whether the natural climate system would be exhibiting this behavior anyway.
In the new study, conducted by the Georgia Institute of Technology and the Scripps Institute of Oceanography, scientists traveled to the central tropical Pacific, where the variations in El Niño-driven temperature and precipitation patterns are most acute. Studying the region’s coral gave them a window into the historical effects of El Niño.
They extracted core samples from large coral rocks that had been pushed by storm activity onto Christmas (Kiritimati) and Fanning Islands, tiny spits of land within Kiribati’s Northern Line Islands. Using radioactive dating, they ascertained the ages of 17 samples, each of which spanned 20 to 80 years in time, allowing them to create a patchwork timeline covering 7,000 years.
Then they looked at the ratio of oxygen isotopes within the coral skeletons as a way of measuring variations in weather patterns. Since temperature and rainfall affect isotope ratios, they were able to glean the environmental conditions present during each phase of the corals’ lifespans. Dips and surges in rain and sea surface temperatures left an imprint in the coral samples, and in their analysis, scientists found significantly more intense and variable El Niño activity in the 20th century than most other periods represented.
“The level of [El Niño] variability we see in the 20th century is not unprecedented,” said the study’s lead author, Georgia Institute of Technology’s Kim Cobb in a statement, noting a similarly severe period in the 17th century. “But the 20th century does stand out, statistically, as being higher than the fossil coral baseline.”
The researchers reluctantly went a step further to connect the increase in El Niño activity to climate change: “We kind of answered the question, is El Niño changing with respect to recent natural variability?” said Cobb. “The answer is yes, tentatively so.” Yet despite the bounty of new data, researchers say they would need to go back even further in time to make a more definitive linkage between climate change and El Niño activity.
They were less ambiguous about the impact of the study on future climate change research. The new data will help other scientists investigate past climate change events in both paleoclimate records and model simulations, Cobb said. “Prior to this publication, we had a smattering of coral records from this period of interest,” she explained. “We now have tripled the amount of fossil coral data available to investigate these important questions.”
Standing in the shower or sitting in the tub, many of us have looked at our wrinkled fingertips and had occasion to wonder: Why do they get so pruney when wet?
Over the years, people have pointed to a number of explanations, most commonly the idea that the wrinkles are simply a reflection of the skin absorbing water. Now, according to a study published yesterday in the journal Biology Letters by researchers from Newcastle University in the UK, we have a definitive (and more interesting) explanation: Pruney fingers are better at gripping wet objects.
The idea was first suggested in a 2011 paper, which showed that the wrinkles that form on our fingers exhibit consistent patterns that allow water to sluice away—indicating that their role is to improve traction, like the tread on a tire. For this paper, an unrelated group of researchers put the theory to the test, letting twenty volunteers soak their fingers in warm water for 30 minutes to get them good and pruney, then testing exactly how long it took them to move wet glass marbles and fishing weights from one container to another.
On average, pruney-fingered participants moved wet marbles 12 percent more quickly than when they were tested unwrinkled fingers. When the same test was performed with dry marbles, the times were roughly the same. Thus, it seems, the hypothesis was proved: pruney fingers do help us grip better.
Other research has shown that the wrinkles form as a result of blood vessels beneath the skin constricting, as directed by the autonomic nervous system. Because this is an active process—rather than merely a byproduct of the skin absorbing water, as previously assumed—scientists began looking for the underlying reason why this might be the case.
The gripping hypothesis makes sense from an evolutionary standpoint, too. “Going back in time, this wrinkling of our fingers in wet conditions could have helped with gathering food from wet vegetation or streams,” study coauthor and behavioral researcher Tom Smulders said in a press statement. “And as we see the effect in our toes too, this may have been an advantage as it may have meant our ancestors were able to get a better footing in the rain.”
If pruney fingers are better at gripping wet objects and don’t slow us down with dry ones, though, the theory prompts a question: Why aren’t our fingers permanently wrinkled? The study’s authors acknowledge this query and admit they don’t have a ready answer, but speculate that permanent pruniness could limit our fingers’ sensitivity or even make them more likely to be cut by sharp objects.