Each year, around 5,300 Golden Warblers – a threatened species – die from collisions with communication towers. Photo: Brian Small

Beneath massive communication towers, fallen bird bodies pile up like confetti. They collide with the steel structures—which can reach heights twice that of the Empire State Building—or fly into the miles of cables radiating around the beacons. Each year, nearly 7 million birds lose their lives to these web-like traps of wire and metal—27 times more birds than were killed in the infamous 1989 Exxon Valdez spill.

The killing season peaks during the time nocturnal migratory birds make their way between Canada and the U.S. Flying in the darkness, they spot the tower lights, become disoriented and begin circling the beams. After a storm, when natural navigational cues like the stars or moon are obscured, mortalities are particularly high.

While the magnitude of causalities is worrying, until now researchers did not know whether or not the avian victims were species of conservation concern or just common sparrows. Research recently published in the journal Biological Conservation, however, confirms scientists’ fears. Members of thirteen threatened North American species succumb each year to the towers. The fallen birds represent between 1 and 9 percent of those species’ total population numbers.

“Certain species of birds, including many already in decline, are killed at communication towers in far greater proportions than their abundance would suggest,” said lead author Travis Longcore, the science director of the Urban Wildlands Group and an associate professor of research at the Spatial Science Institute at the University of Southern California, in an email. “And it’s not just these thirteen species we have to worry about—they’re just the ones being killed at the highest rates,” he continued. “Many more species of concern are killed at lower rates, too.”

To figure out mortality by species and regions, Longcore and his co-authors constructed a database of species deaths based on verifiable, available records. Then, they calculated the mean proportion of each species killed and compared those statistics with overall mortality rates for each species’ total population in the U.S. and Canada.

All in all, they found, 97 percent of the birds being killed are passerines, or songbirds. Among the threatened birds that are dying are the Yellow Rail, with 2,200 annuals mortalities, representing 8.9 percent of the species’ total population; the Golden-winged Warbler, with 5,300 annual deaths, representing 2.5 percent of the population; and the Swainson’s Warbler, with 7,500 annual deaths, representing 8.9 percent of the population. Other species, though not currently of conservation concern, still suffer formidable losses. Red-eyed Vireos, for example, relinquish 581,000 lives to communication towers each year, and around 499,000 Ovenbirds die this way, too.

Last year, the same team found that around 1,000 of the towers, used for television and radio broadcast, are responsible for 70 percent of the bird deaths. Those 1,000 towers, the team noted, stand 900 feet or higher, representing the largest of North America’s 70,000-odd communication towers included in the original study. In their follow up study, they identified the deadliest sites, which are in Texas, Louisiana, Florida and the Midwest. The findings are no surprise; the Southeastern coastal plain and the Midwest regions contain the highest concentrations of the tallest towers on the continent.

The Migratory Bird Treaty Act of 1918 makes it illegal to kill migratory birds in the U.S., so the researchers hope their findings may be used to better regulate communication towers. Eliminating the steady-glow red lights from the towers and replacing them with blinking lights—the same fix adopted by the Federal Aviation Administration—may reduce bird mortality by 50 to 70 percent.

The study also carries another lesson, Longcore said. Simply counting up the total number of birds killed by wind turbines, cats, windows, pesticides or communication towers across the country and then making crude comparisons between mortality sources can be misleading, he pointed out. The most impactful data—the types of species killed, and where, and when and how—often lurk beneath those surface figures. “Simple estimates of total ‘bird’ mortality are insufficient; it matters which species are being killed,” he said. “Each mortality source may be significant, but for different species and in different places.”

Coral from the Northern Line Islands reveals a link between climate change and El Niño. Photo by Forest Rohwe

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.”

A new study suggests a link between diet soda and depression, but it’s important to remember the difference between causation and correlation. Image via Flickr user DavidMartynHunt

Despite a lack of evidence in the scientific literature, we’ve seen aspartame—the calorie-free sugar sweetener found in diet drinks—blamed for a variety of health problems, everything from multiple sclerosis to migraine headaches. But here’s a new one: clinical depression?

In a preliminary release of a study to be published by Honglei Chen and colleagues from the National Institutes of Health, a survey of 263,925 adults nationwide indicated that consumption of sweetened drinks—especially diet sodas—was associated with an increased chance of a depression diagnosis. The authors, who will present their work at the American Academy of Neurology’s annual meeting in March, released only a summary of their study today.

To come to the findings, the researchers combined old data with new. They began by examining a survey originally conducted in 1995 and 1996 in which adults between the ages of 50 and 71 recorded their daily soda, tea, fruit punch and coffee consumption. Then, for this study, they returned to the same survey participants more than a decade later and asked if they had been diagnosed with depression in the years since 2000.

They found that those who drank four or more cans of sweetened drinks (whether soda, diet soda or fruit punch) had a significantly higher chance of being among the 11,311 study participants who were later diagnosed with clinical depression that those who didn’t. For sodas as a whole, there was a 30 percent greater chance of depression, but diet sodas carried a further 22 percent increase as compared to regular ones. Interestingly, regular coffee consumption was associated with a 10 percent lower chance of depression.

Does this mean you should stop drinking diet Coke and starting chugging coffee immediately? Probably not. This type of suggested link between two seemingly unrelated factors is an ideal time to bring up the difference between causation and correlation. Do the ingredients in both diet sodas and normally-sweetened drinks trigger changes in brain chemistry that lead to depression? Or are people with the tendency to become depressed simply more likely to drink these beverages in the first place?

Without the full paper, it’s hard to know for sure—we don’t know if the study’s authors controlled for all relevant factors, making sure to compare study participants who were alike in all ways except for their beverage consumption. As a result, a third, unrelated factor may cause people to both drink more soda and become depressed more frequently. Since the study is backward-looking, it’s especially hard to rule this out: The researchers can’t go back to 1996 and make sure to ask the participants every potentially relevant question to ensure that all potentially important factors have been taken into consideration.

Additionally, the fact that an association was found for both regular and diet sodas makes a causative link seem less likely. For that to be the case, either both sugar and aspartame must trigger depression, but at different frequencies, or a third ingredient in both sodas is responsible, but is somehow modulated by the presence of the natural or artificial sweetener.

So, what’s the simplest explanation? Those who like to drink a lot of diet soda are more likely to already be at risk of developing depression. And people who like to drink a lot of coffee are already less likely to be among this group. Perhaps, then, your underlying preference for how you get your energy buzz—whether through coffee or sweet drinks—may reflect something about your mental state.

Research shows that the FDA’s proposed graphic warning labels would be more effective than the current text-only ones. Image via FDA.

More than 40 countries around the world force cigarette companies to print graphic images of things like decaying teeth, open-heart surgeries and cancer patients on their packs, in an effort to discourage smoking by directly linking cigarettes with their most gruesome effects. The United States, however, is not one of these countries: The U.S. Food and Drug Administration unveiled graphic designs in November 2010, but repeated lawsuits by the tobacco industry have delayed implementation of the new warnings.

If and when the labels do hit, the images could go a long way towards continuing the decline in smoking rates across the country. That’s because, as new research demonstrates, seeing these images every time a person reaches for a pack is a more effective deterrent than a text-only warning. The research also indicates that the graphic warnings are especially powerful in discouraging low-health literacy populations from smoking—the one group in which smoking rates have remained stubbornly high over the past few decades.

The study, published yesterday in the American Journal of Preventive Medicine [PDF], was conducted by James Thrasher of the University of South Carolina and colleagues. A control group of 207 smokers saw text-only warning labels, while 774 smokers evaluated nine different graphic labels, both images proposed by the FDA and a selection of others currently used in foreign countries.

The smokers were asked to judge each label on a scale of one to ten for credibility, relevance and effectiveness. The results were unequivocal: The text-only warnings’ average ratings were mostly in the fives and sixes, while simpler text messages combined with striking graphics scored in the sevens and eights across the board.

These differences were especially large for the group the researchers called low-health literacy smokers–people with less education who are less likely to be knowledgeable about the risks of smoking. This group gave much higher ratings for credibility, in particular, to the labels that showed them the health problems that arise from smoking, rather than text labels that merely told them. “The present study provided the first direct test of the hypothesis that pictorial health warning labels work better than text-only labels among people with low health literacy,” Thrasher said in a statement.

The study also found that graphic types of labels (left) were more effective than those depicting human suffering (middle) or those that were merely symbolic (right). Image via American Journal of Preventive Medicine

Among the labels with images, the study compared three different types: graphic (those that directly showed body parts damaged by smoking), human suffering (those that showed someone in a hospital bed, for example) and symbolic (more abstract images, such as a gravestone). Perhaps unsurprisingly, the first category was consistently rated as the most effective in discouraging smoking. It seems nothing so powerfully scares someone away from taking another puff than a picture of what their teeth, lungs or throat will look like after a lifetime of doing so.

Thrasher feels that these types of findings should be taken into account when agencies such as the FDA design cigarette warning labels, to be sure they reach all demographics. “The FDA should consider implementing warning labels with more graphic imagery in order to maximize the impact of warnings across different populations of adult smokers, including more disadvantaged smokers,” Thrasher said.

A new study indicates that fraud in the biomedical sciences occurs but is exceedingly rare. Image via RDECOM

Gallup’s annual poll of which professions are the most trustworthy doesn’t ask about scientists, but it’s safe to say that at the very least they’d rank far higher than the used car salespeople and members of Congress at the bottom.

At the same time, among the thousands of people globally who practice science and publish their results, some minority likely yield to the temptation to massage data to achieve attention-getting (and funding-friendly) results. In recent years, it has become politically useful for some to seize upon this possibility and allege deliberate scientific fraud. (Charges that man-made climate change is a widespread scientific conspiracy have only become more common since the so-called Climategate scandal of 2009, despite several investigations that have failed to find any evidence of fraud or scientific misconduct.)

But how often do scientists actually lie about their data? In other words, how much should we trust in them?

The answer, at least according to a study published today in the Proceedings of the National Academy of Sciences, is that on the whole, scientists are a pretty honest group. In the paper, medical researchers from the University of Washington and elsewhere found that of the more than 25 million biomedical research-related articles published in the National Institutes of Health PubMed database that date back to the 1940s, 2,047 were retracted at some point since their publication. That’s less than 0.01 percent of all the papers in the database.

The researchers broke their results down further, attempting to attribute each retraction to a type of cause. By their accounting, 21.3 percent were due to honest error, such as unintentional misinterpretation of data. Meanwhile, 67.4 percent of the retractions could be attributed to some sort of misconduct, including fraud or fabrication (43.4 percent), plagiarism (9.8 percent) and duplicate publication (14.2 percent). When compared with the articles retracted before 1975, those retracted afterward were ten times more likely to be fraudulent, as opposed to an honest mistake.

The overall modest rate of fraud could explain why the authors of the blog Retraction Watch, which documents retracted papers, have encountered opposition. Some say that directing attention towards isolated cases of dishonesty disproportionately increases public mistrust in science as a whole. “The argument goes something like this,” they wrote in May in Lab Times. “Scientific fraud is rare, so focusing on misconduct gives a distorted picture of research that will only give ammunition to critics, who want to cast doubt on subjects such as climate change and vaccine safety.”

One response might be that we don’t actually know how rare fraud is, despite the 0.01 percent retraction figure out this new PNAS study. As the study’s authors note, in many cases an article might be suspect but a journal doesn’t have enough proof to actually retract it. In 2005, for example, The Lancet “expressed concern” about the results of a study that found a correlation between a Mediterranean diet and a reduced risk of heart disease, but they didn’t ultimately retract the paper.

Moreover, we have no way of knowing how many suspect data sets never even come to light. A fabricated data set might not prove replicable by other researchers, but in many cases, it’s doubtful this would prompt them to allege dishonesty. Historically, many cases of scientific fraud are exposed only by internal whistle-blowers.

Recent events, though, indicate that we might be entering an age in which scientific discoveries actually help us detect fraud, or at least some types of it. This past July, social psychologist Uri Simonsohn of the University of Pennsylvania garnered headlines by using an innovative statistical analysis to detect fabricated data in the work of social psychologist Dirk Smeesters, who had written a paper finding a positive effect for color on consumer behavior.

Simonsohn’s technique is complex but relies upon the fact that people are notoriously bad at faking sets of data characterized by the same sort of randomness that occurs in real events. Simonsohn told Nature that “The basic idea is to see if the data are too close to the theoretical prediction, or if multiple estimates are too similar to each other.”

Soon after Smeesters’ resignation, Simonsohn made his algorithm public, encouraging researchers to publish their raw data and for others to put it to the test. He hopes that the real possibility that any researchers tempted to manipulate their data could be caught will act as a powerful deterrent. This, in theory, would not only decrease the amount of fraud but it would also increase the trust we can put in the products of science as a whole.

New “transient electronics” dissolve in the presence of water, opening up a new range of possible applications. Image via the Beckman Institute, University of Illinois and Tufts University

For most of us, an ideal electronic device is durable and long-lasting. An interdisciplinary team of researchers, though, has developed a new class of circuits that forces us to rethink our concept of what electronics can do in the world.

Their invention—an ultrathin, clear, silicon-based circuit that functions for a precise period of time, ranging from minutes to years, then dissolves completely in water—could lead to routine implantation of tiny electronics inside the body or in the environment without any need to extract them after use. The research team, from Tufts University, Northwestern University and the University of Illinois, reveals their advance in a paper published today in Science. They refer to it as an initial entry into a new field called “transient electronics.”

“These electronics are there when you need them, and after they’ve served their purpose they disappear,” said Yonggang Huang, who led the Northwestern portion of the team, which focused on theory, design and modeling. “This is a completely new concept.”

The circuits inside conventional electronics are made of silicon, a material that naturally dissolves in water over time but at rates that mean a typical circuit would take hundreds of years to disappear. The sheets of silicon that make up these new transient electronics, however, are just a few nanometers thick, so they can dissolve over the course of minutes when they come in contact with even a tiny volume of water or a body fluid. Watch how the circuit dissolves (almost like a breath-freshening strip) when it gets sprinkled with water, 15 seconds into this video:

So far, by printing circuits using soluble conductors (like magnesium or magnesium oxide) on the ultrathin silicon sheets, the researchers have created functional transistors, diodes, wireless power coils, temperature and strain sensors, photodetectors, solar cells, radio oscillators, antennas and even simple 64 pixel digital cameras that dissolve completely.

The research team imagines a range of different applications for their invention. Currently, surgeons are reluctant to implant medical monitoring devices (say, to check for an infection post-surgery) because of the difficulty of extracting them. But an implant made out of transient electronics that performed a diagnostic or monitoring function for a set period of time, then dissolved safely in the body, could become a routine way for a doctor to follow up on a patient’s progress after surgery. Other transient devices could monitor temperature or muscle activity, or deliver medicine internally.

In rats, the team successfully demonstrated an implant that monitored for a bacterial infection at a surgical incision site and could eradicate it via heating if necessary. Three weeks after being implanted, only traces of the circuit remained in the rat’s skin.

The researchers implanted a transient circuit board into a rat’s skin to test the viability of using such technologies as post-surgery monitoring devices in humans. Image via the Beckman Institute, University of Illinois and Tufts University

Additionally, transient circuits could be used in environmental monitoring situations, such as using wireless sensors that are applied after an oil spill to track ground conditions before dissolving after a set period of time. Monitors could also be placed on buildings or roadways to detect gradual structural deformation over time. Transient circuits could even make their way into consumer electronics—a phone’s inner circuitry could perhaps be designed to dissolve in the presence of a particular liquid—to combat the increasing amount of electronic waste that’s produced as we frequently upgrade phones or other devices.

Because silicon is naturally abundant in the environment and the conducting material, magnesium, is biocompatible—and naturally occurs in the body—the researchers believe that the circuits will not harm our health or the environment when they dissolve. Of course, it remains to be seen whether this is the case, and further testing is necessary before the invention is implemented.

Transient circuits could be used in environmental monitoring applications, eliminating the need for cleanup afterward. Image via the Beckman Institute, University of Illinois and Tufts University

Each of these various applications would require different rates of decay. “A medical implant that is designed to deal with potential infections from surgical site incisions is only needed for a couple of weeks. But for a consumer electronic device, you’d want it to stick around at least for a year or two,” said John Rogers, who led the University of Illinois group that worked on experimentation and fabrication.

To control just how long a circuit sticks around, the researchers cover it with protective silk coats of different thicknesses. The thicker the silk, the longer it takes to dissolve, and only then does the silicon start to disintegrate. Until the silk is gone, the circuits can function while completely submerged in water or a phosphate buffered saline liquid, chemically similar to fluids in the human body.

The research group is currently refining their designs and conducting more animal tests, as well as working with a semiconductor manufacturer to test the potential for industrial-scale manufacturing. The fact that the technology relies upon printing circuits on a silicon surface—like the vast majority of electronics in existence—means that minor alterations to the manufacturing process could yield functional transient circuits.

“It’s a new concept, so there are lots of opportunities, many of which we probably have not even identified yet,” Rogers said. “We’re very excited. These findings open up entirely new areas of application.”

A new anti-acne approach acts upon Propionibacterium acnes, the naturally-occuring bacteria that cause outbreaks. Image via Wikimedia Commons/Bobby Strong

Acne afflicts nearly 90 percent of Americans at some point in their lives, but scientists have made surprisingly little headway in understanding and combating the skin condition. For sufferers of severe acne, the treatments available— benzoyl peroxide, antibiotics and Accutane—are limited in effectiveness and can cause a range of undesirable side effects.

New research, though, is pointing towards a novel approach that could someday serve as a solution: the use of viruses to attack the bacteria on the skin that cause acne breakouts. After studying the Propionibacterium acnes phages virus and sequencing its DNA, a team of researchers from the University of California, Los Angeles and the University of Pittsburgh believes that it could be an ideal candidate for the development of a new sort of anti-acne therapy. Their findings were published today in the journal MBio.

“Acne affects millions of people, yet we have few treatments that are both safe and effective,” said Robert Modlin of UCLA, a co-author of the paper. “Harnessing a virus that naturally preys on the bacteria that cause pimples could offer a promising new tool.”

An electron microscope magnification of P. Acnes phages, the virus that naturally infects and kills P. acnes bacteria. Image via the University of Pittsburgh

Acne is caused by blockages in the skin’s follicles formed by an oil called sebum, which is produced by the body to prevent hair follicles from drying out. When sebum forms a plug in the follicle, it allows the naturally occuring bacteria P. acnes to trigger an inflammatory response in the skin, leading to swollen red bumps and other symptoms. Antibiotics and other prescription acne treatments work by killing these bacteria, but over time, antibiotic-resistant strains of the bacteria have emerged, rendering these products less effective.

The research team decided to explore the potential of an entirely different method—killing the bacteria by using a type of virus that also lives naturally on the human skin and has specifically evolved to infect P. acnes bacteria. To do so, they gathered both the bacteria and 11 different versions of the virus (P. acnes phages—named for the host bacteria it preys upon) from the faces of volunteers using over-the-counter pore-cleaning strips.

An analysis of the different viruses’ DNA, as collected from the volunteers, revealed surprisingly little genomic diversity (all samples were identical for at least 85 percent of their DNA)—a trait that would make developing an acne treatment simpler because it indicates that any formulation of the virus would be effective in killing the P. acnes bacteria for many different people. This conclusion was bolstered by the fact that, when the researchers cultured bacterial samples from different volunteers and added the varieties of virus, the viruses were effective in killing a broad range of different sub-varieties of bacteria.

The clear spots in this cultured colony of P. acnes bacteria indicate where the virus was effective in killing it. Image via UCLA/Modlin Lab

Additionally, the specificity of the virus’ killing mechanism makes it an appealing candidate for an anti-acne treatment, in contrast to antibiotic treatments that can also harm populations of beneficial varieties of bacteria that live on our bodies. “Phages are programmed to target and kill specific bacteria, so P. acnes phages will attack only P. acnes bacteria, but not others like E. coli,” said lead author Laura Marinelli of UCLA. “This trait suggests that they offer strong potential for targeted therapeutic use.”

The researchers believe that the key to the virus’ killing ability is an enzyme it produces called endolysin, which may act by breaking down bacterial cell walls. A better understanding of how this enzyme works is a next step towards eventually developing a treatment, either based on endolysin isolated from the virus, or using the virus itself.

The team plans to test endolysin on its own to determine if can kill P. acnes bacteria on its own, without the virus. If the enzyme is successful in petri dishes, they may proceed by testing an extract made from the virus on participants to see whether it is a safe and effective way to prevent acne in human skin.

Engaging in a firefight, along with other combat stresses, could lead to long-term changes in the connections between the midbrain and prefrontal cortex. Photo by U.S. Army Sgt. Matthew C. Moeller, 5th Mobile Public Affairs Detachment

Some soldiers who serve in Afghanistan or other war-torn countries return home with visible injuries: concussions, broken bones or amputated limbs. Many others, though, suffer from injuries we can’t visibly see. The daily strain of being exposed to armed combat, enemy fire and unpredictable explosions can lead to a range of behavioral symptoms, including fatigue, slower reaction times and a difficulty in connecting to one’s immediate surroundings.

A new study of soldiers returning home from Afghanistan, published today online in the Proceedings of the National Academy of Sciences, hints at the underlying cause for these behavioral changes. Researchers from the Netherlands and elsewhere used neurological exams and MRI scanning techniques to examine 33 soldiers before and after a four-month deployment in NATO’s International Security Assistance Force, and compared them to a control group of 26 soldiers who were never deployed.

The results were sobering—and indicate that a relatively short period of combat stress can alter an individual’s neurological circuitry for a long time.

As compared to the pre-deployment baseline tests and the control group, the returning soldiers’ brains showed distinct differences, despite the fact than none had suffered physical injuries and only one had exhibited enough symptoms to be clinically diagnosed with post-traumatic stress disorder. A pair of different techniques using MRI—diffusion tensor imaging, which measures the diffusion of water in the brain, indicating tissue density, and fMRI, which measures blood flow in various parts of the brain—revealed that the soldiers’ midbrains had reduced tissue integrity and showed less neuron activity during a working memory task.

Working memory is related to sustained attention, the researchers note, which could explain the results of the study’s neurological performance tests. As part of the tests, the soldiers were asked to complete a complex, mentally draining task known as a dot cancellation test. When compared to the other groups, those returning from combat committed more errors in the task over time, indicating a reduced ability to pay sustained attention. On an individual basis, participants with a greater reduction in midbrain activity were more likely to be error-prone in completing the dot cancellation test.

Both of these changes appeared when the soldiers were tested six weeks after combat, but mostly disappeared when they returned for a follow-up another 18 months later. However, a related change in the soldiers’ neurological makeup—a reduction in connections between their midbrain and prefrontal cortex—persisted in the follow-up, nearly two full years after exposure to combat was over. This is good reason, the researchers feel, to suggest that combat stress can alter the brain over the long term, and perhaps alter other areas of the brain as well.

“These results suggest that the human brain can largely recover from the adverse effects of stress,” they write in the study. “However, the results also reveal long-term changes that may increase vulnerability to subsequent stressors and lead to long-lasting cognitive deficits.”

Other researchers have examined how acute periods of stress can alter brain chemistry. Many believe that sudden bursts of hormones associated with stress, such as cortisol and norepinephrine, can permanently impair brain tissue.

Of course, lab studies can test returning soldiers’ ability to pay sustained attention to a task for several minutes, but whether combat has affected their ability to navigate social situations or make long-term decisions is another question entirely. The researchers involved, though, note that we should consider the possibility.

“The persistent changes in mesofrontal connectivity may increase the vulnerability to subsequent stressors and promote later development of difficulties with cognitive, social and occupational functioning,” they write. What soldiers see in combat, it seems, can stay with them when they come back home.

A new discovery could lay the groundwork for a future oral male contraceptive pill. Photo via Wikimedia Commons/Andrew Wales

The 1960 approval of the first oral contraceptive pill by the FDA for U.S. markets had a wide range of impacts on the nation. The availability of a reversible and reliable contraceptive method was unprecedented in human history; its rapid spread played a crucial role in the sexual revolution, made the cover of TIME Magazine and may have led to more women attending college and graduate school.

Ever since, scientists have been attempting to figure out a way to develop a contraceptive pill for men. Today, researchers from the Dana-Farber Cancer Institute and the Baylor College of Medicine announced that they have identified a chemical compound that could lay the groundwork for a future oral drug that reversibly inhibits male fertility.

“Our findings demonstrate that, when given to rodents, this compound produces a rapid and reversible decrease in sperm count and mobility with profound effects on fertility,” says James Bradner, the senior author of the study documenting the advance, to be published tomorrow in the journal Cell. ”These findings suggest that a reversible, oral male contraceptive may be possible.”

The researchers actually stumbled upon the compound, called JQ1, while on an entirely different mission: trying to find a cure for cancer. The chemical (named after lead chemist Jun Qi) was originally synthesized at Dana-Farber to block the activity of a cancer-causing protein known as BRD4—and in fact, tests in several laboratories have shown it to be a promising treatment for several forms of cancer, including leukemia, multiple myeloma and lung cancer.

“We previously had demonstrated it could inhibit a specific protein called BRD4, but we learned that the molecule also inhibits a related molecule called BRDT,” Bradner says. “BRDT has no role specifically in cancer but is very important for the development of mature sperm, and so we wondered: Could the JQ1 molecule, intended originally for cancer, have activity as a male contraceptive agent?” Computer modeling suggested that the molecule could be effective in this role, but the only way to know for sure would be to test it on live animals.

So Bradner and his colleagues sent samples of JQ1 off to Martin Matzuk‘s lab at Baylor, where his team injected the isolated compound into male mice daily for several weeks and allowed them to mate with females. Some mice required 50 mg per day, some 75 and some 100, but ultimately, the results were all the same: Despite their avid attempts at breeding, JQ1 prevented the mice from producing offspring. Examination showed that the mice had significantly lower sperm counts and sperm with reduced mobility, as compared with a control group of mice that received injections of an inactive fluid.

The testes of the control group (left) were packed with fully mature sperm, while those of mice that had been injected with JQ1 (right) had much lower quantities. The black arrow points to large nucleated cells, which indicate incomplete sperm maturation. Photo via the Dana-Farber Cancer Institute

The molecule works by entering the testes and disrupting spermatogenesis, the process by which sperm mature into functional male gametes. Specifically, JQ1 interferes by binding to a pocket of BRDT, which facilitates the expression of genes important for sperm maturation.

Crucially, the mouse experiments showed that JQ1′s effects were rapid and reversible: In all mice, sometime between a month or two after JQ1 injections were discontinued, normal sperm production and fertility resumed. Additionally, the drug did not affect mating behaviors, alter levels of testosterone or other hormones or produce negative health effects in offspring that were conceived after JQ1 injections were stopped.

All of this does not mean that doctors will start prescribing a male contraceptive pill anytime soon. “At the time we made JQ1, we had not optimized it for its drug-like properties,” Bradner says. “So no, JQ1 is not intended for human use as a male contraceptive agent.” In addition to conducting further experiments to establish the safety and efficacy of JQ1 in humans, researchers would need to produce a form of it that could be delivered orally and enter the bloodstream in order to make a male contraceptive pill.

Still, because the structure of BRDT in mice and humans is similar, the new development is likely to get fans of a potential male contraceptive excited. “The structural and biochemical data provided by this paper are effectively a blueprint for developing a drug-like derivative of JQ1 that could be very potent,” Bradner says. ”JQ1 shows initial promise as a lead compound for male contraception.”

Octopoteuthis deletron, a species of squid found deep in the cold waters of the Pacific Ocean, has many natural predators: elephant seals, giant grenadier fish and the mysterious Perrin’s beaked whale.

To protect itself, the squid has developed a a rather unusual defensive mechanism, recently discovered by cephalopod researcher Stephanie Bush of the University of Rhode Island: When attacked, the squid plants its arms in its predator and then breaks them off. While seemingly counterproductive, there’s a reason for this tactic.

“If a predator is trying to attack them, they may dig the hooks on their arms into the predator’s skin. Then the squid jets away and leaves its arm tips stuck to the predator,” Bush explains. “The wriggling, bioluminescing arms might give the predator pause enough to allow the squid to get away.” In the squid’s extremely dark habitat—anywhere from 1,300 to 2,600 feet below the surface—this distracting, flashing “disarmament” could be the difference between staying alive and getting eaten.

Scientists have known for some time that lizards and other land-based species can voluntarily detach their appendages to elude predators, a tactic they call “arm autonomy.” But Bush’s discovery, revealed in a paper published this month in the journal Marine Ecology Progress Series, is the first ever documented case of a squid engaging in the practice.

Bush says she first became interested in looking into the phenomenon when she was working as a researcher at the Monterey Bay Aquarium Research Institute and noticed that many wild squid had extremely blunt arms that seemed to be in the process of regenerating. Scientists had speculated that damage caused by researchers’ nets was the underlying reason, but Bush wasn’t so sure. So she and her colleagues sent a remotely-controlled submersible equipped with a video camera deep into the waters of the Monterey Bay Submarine Canyon, found a squid and poked it with the control arm of the vehicle.

“The very first time we tried it, the squid spread its arms wide and it was lighting up like fireworks,” she says. Because the metal control arm was smooth, though, the squid’s arms slid off of it without detaching.

The team then came up with a makeshift solution: They attached a brush used to clean their laboratory glassware to the control arm of the vehicle and then used that to poke the squid. “It then came forward and grabbed the bottlebrush and jetted backwards, leaving two arms on the bottlebrush,” recounts Bush. “We think the hooks on its arms latched onto the bristles of the brush, and that was enough for the arms to just pop off.” Luckily, the team caught the fascinating encounter on camera for us to enjoy.

Bush later found other squid of the same species and repeated the test. Although some were more hesitant to discharge their arms than others, fighting back against the fearsome bottlebrush at first, all engaged in the unusual tactic after sufficient provocation. None of the other squid species she tested did the same. The species appeared to discharge their arms efficiently: Looking under a microscope afterward, Bush saw that most arms were torn as close as possible to the stress point, minimizing the amount of tissue lost.

The squid can regrow their arms, but that takes energy, and swimming around without an arm or two could make capturing food and mating more difficult (the bioluminescent organ on the arms’ tips are used to attract mates). Still, the strategy is a smart one under sufficiently dire circumstances. “There is definitely an energy cost associated with this behavior,” Bush says, “but the cost is less than being dead.”

Researchers discovered that simply smiling can reduce stress and increase well-being. Photo via Wikimedia Commons/Zitona Qatar

It sounds like the most useless advice imaginable: Just put on a happy face. Conventional wisdom is that smiling is an effect of feeling happy, rather than the other way around. Simply smiling in stressful situations can’t possibly make you feel any better, right?

Wrong. A fascinating new study by University of Kansas psychologists that will soon be published in the journal Psychological Science indicates that, in some circumstances, smiling can actually reduce stress and help us feel better.

“Age old adages, such as ‘grin and bear it,’ have suggested smiling to be not only an important nonverbal indicator of happiness but also wishfully promotes smiling as a panacea for life’s stressful events,” said researcher Tara Kraft. “We wanted to examine whether these adages had scientific merit; whether smiling could have real health-relevant benefits.”

To investigate the claim, the researchers recruited 169 willing college students for a hands-on experiment. But they had to engage in a bit of deception. Actually telling the participants that they were testing whether smiling would make them happier would have distorted the results, so the students were told that the experiment was about multi-tasking.

First, the participants were instructed on how to perform an unusual task: holding chopsticks in their mouths in particular ways that prompted various facial expressions. They were divided into three groups, one that was taught how to form a neutral expression, one that learned how to form a normal smile, and one that was instructed to form a Duchenne smile (also known as a genuine smile), which involves the use of eye muscles, as well as those around the mouth. Additionally, only half of the smilers actually heard the world “smile” during the learning phase; the others were simply taught how to hold the chopsticks in a way that produced smiles, without the expression being identified as such.

Next, the students were put in “multi-tasking situations” that were intentionally designed to be stressful. In the first one, they were asked to trace a star shape with their non-dominant hand while looking only at a mirror image of it, and were misled about the average person’s accuracy in completing the task. While attempting to execute the maneuver with as few errors as possible to win a reward (a chocolate), they were continually reminded to hold the chopsticks in their mouths to maintain the intended facial expression. Afterward, they were instructed to do the same as their hands were submerged in ice water.

During and after each of these tasks, the participants’ heart rates were continuously monitored, and at regular intervals, they were asked to report their levels of stress.

The experiment’s findings were startling. As a whole, the smilers had lower heart rates while recovering from the stressful tasks than those who had assumed neutral expressions, and those with Duchenne smiles had lower heart rates yet. Even those who were smiling only due to their instructed chopstick position—without explicitly being told to smile—showed the same effect. Since heart rate is an indicator of the body’s stress response, it seems as though the act of smiling actually reduced the participants’ overall stress level.

Most intriguingly, a small difference was noted in the self-reported stress levels of the groups after the ice water task. Although the amount of positive feelings declined for all participants after putting their hands in ice water, the decline was slightly smaller for smilers than for those with neutral expressions.

Researchers are baffled regarding why this might happen. The connection between facial expressions and underlying mental states is still largely unexplored, but some have suggested that smiling could reduce levels of cortisol, a stress-related hormone. This study flips our traditional understanding of emotion and appearance on its head: Feeling good could sometimes be a consequence of smiling, not just the other way around.

What does this mean for your daily life? When feeling stressed, try forcing a smile on your face. If you can manage a genuine, Duchenne smile—what people often refer to as “smiling with your eyes,” not just your mouth—that’s even better. For whatever reason, forcing yourself to look happier could actually end up helping you feel happier.

“The next time you are stuck in traffic or are experiencing some other type of stress you might try to hold your face in a smile for a moment,” said Sarah Pressman, one of the researchers. “Not only will it help you ‘grin and bear it’ psychologically, but it might actually help your heart health as well.”

There are pros and cons to running barefoot. Photo via Wikimedia Commons/Stilfehler

With the Olympics heating up and track and field events set to start next week, it’s an appropriate time to consider the most controversial debate in the running community: Should we lace up a pair of running shoes when we go for a jog, or simply venture out barefoot?

Over the past few years, barefoot running has gone from an oddball pastime to a legitimate athletic movement, and the small number of actual barefoot runners is joined by a much larger number who’ve adopted minimalist running shoes.

Proponents of barefoot running argue that our bodies evolved for shoeless locomotion. Covering up one of our most sensitive, flexible parts distorts our natural stride and prevents foot muscle development. Instead of striding gracefully and landing on the mid or forefoot, running shoes lead us to carelessly land on a heavily cushioned heel. Decades of athletic footwear development have led to bigger, more protective shoes—which have only weakened our feet and made us unable to run the way we are naturally meant to.

The opposing camp—which, after all, still includes the vast majority of runners—points to a number of advantages in wearing shoes. Modern advances in footwear can prevent flawed running tendencies such as overpronation (when a flat-footed runner’s ankle rolls inward with each stride) that lead to injuries like shin splints. If you’ve run with shoes your whole life, going barefoot requires dramatically altering your stride, which often results in other injuries. And, on the most fundamental level, shoes protect us from broken glass, nails, and other dangerous debris often found on city streets and sidewalks.

Now, science weighs in—and the results are decidedly mixed. An analysis of studies University of Central Florida professor Carey Rothschild, published last week in the Journal of Strength and Conditioning Research, examines the body of research that has been conducted on barefoot running.

“The research is really not conclusive on whether one approach is better than the other,” she said in a press release. “There is no perfect recipe.”

The study’s findings included some that barefoot runners will find gratifying. They are indeed more likely to land on their mid-foot or the ball of their foot, avoiding the harmful practice of “heel-striking.” Previous research has shown that landing on the heel generates sudden, powerful impacts that are equivalent in force to several times a runner’s body weight. These impacts–which occur about a thousand times during each mile run—lead to injuries in the knees, hips, and other areas. Running shoes promote heel-striking because of the thick cushioning below the heel, and roughly 75% of shod American runners run this way.

There are dangers to barefoot running as well, though, and they mainly stem from runners trying to switch to an entirely new stride too quickly after ditching their heavily-cushioned shoes. ”The bottom line is that when a runner goes from shoes to no shoes, their body may not automatically change its gait,” Rothschild said. Stress fractures on the front part of the foot and increased soreness in the calves can result from suddenly attempting to shift weight away from the heels after running one way for years. Still, of the barefoot runners Rothschild surveyed, 42% reported no negative effects from the switch.

“There are ways to help make that transition smoother and lower the risk of injuries,” she said. Before ditching shoes, she recommends a thorough physical exam and biomechanical assessment from a physical therapist or running specialist. Then, the transition to bare feet should be gradual, and ideally conducted with the help of a coach. Runners can start by alternating short barefoot runs with longer shod jogs, or using minimalist shoes, lighter footwear with less cushioning that offer a way to ease into barefoot running.

For a sport that’s all about speed, this might be counterintuitive—but for those thinking of running barefoot, the most important thing is taking it slow.

A new study uses high-speed videography to examine how mosquitoes survive the impact of raindrops. Photo courtesy of the Georgia Institute of Technology

Summer’s here. Along with barbecues, beach excursions and baseball games, that also means the arrival of a particularly unwelcome visitor—the mosquito.

But as we cringe, imagining the hordes of mosquitoes that will bother us shortly, we’ve also got to hand it to them—they’re remarkable hardy creatures, resisting all manner of sprays, repellents, candles and anything else we throw at them. And one of their most amazing abilities is that they can remain in flight in the midst of one of nature’s own attacks: a falling raindrop.

For a mosquito, getting hit with a raindrop is the equivalent of a human getting hit by a 3 ton object—something roughly the size of a pickup truck. An individual raindrop is about 50 times the mass of a mosquito, and the drops fall at speeds as fast as 22 miles per hour. Yet the tiny insects are able to survive countless collisions during the course of a storm, when these truck-sized hazards are plummeting all around them.

How do they do it? According to a study published earlier this week in the Proceedings of the National Academy of Sciences, it is the mosquito’s tiny size—along with a zen-like approach of passive resistance—that allows it to stay in flight despite these massive collisions.

Mosquitoes, it turns out, combine an extremely strong exoskeleton with a minuscule mass to minimize the force of each raindrop when it hits. The fact that they are so much lighter than the raindrops means that the drops lose very little momentum when they collide with the mosquitoes, which translates into very little force expelled onto the insect.

Additionally, instead of standing strong against the drops, or even trying to dodge them, mosquitoes simply go with the flow. ”As the raindrop falls, rather than resisting the raindrop, they basically join together kind of like a stowaway,” David Hu, an engineer at Georgia Tech and an author of the study, told NPR. “So as a result they get very, very little force.” The impact of the raindrop can knock the mosquito partly off course, but it doesn’t harm the insect nearly as much as it would if it were absorbed as a direct hit.

Moments after the mosquitoes latch on to the raindrops, they use their wings and long legs as miniature sails to lift themselves off the falling droplets before they crash into the ground, as shown in the video below. The main danger, the researchers found, is when mosquitoes are hit by raindrops when they are already close to the ground, because if they can’t dislodge in time, they’ll be slammed into the earth at the same speed as the falling drop.

How did the research group, led by Hu’s doctoral student Andrew Dickerson, figure out the mosquitoes’ strategy? ”Hitting a mosquito with a raindrop is a difficult experiment,” Hu said. “The first thing we did was drop small drops from the third floor story of our building onto a container of mosquitoes, and you can imagine that didn’t go very well. It’s kind of like playing the worst game of darts you can imagine.”

Eventually, the researchers brought the experiment inside, constructing an acrylic mesh cage to contain the mosquitoes that would also permit the entry of water drops.

Better understanding how insects deal with nasty weather could help engineers in designing biologically-inspired micro air vehicles, like the Nano Hummingbird, above

They then hit the insects with tiny jets of water to simulate the velocity of falling raindrops, and filmed six Anopheles mosquitoes entering the water stream. They used a high-speed camera that captured 4000 frames per second (a typical video camera captures 24 frames per second). All six of the insects survived, and the footage—along with theoretical equations—allowed the scientists to better understand the insects’ remarkable ability to deal with rain.

The experiments were also conducted with an eye towards practical engineering. The design and construction of micro air vehicles (MAVs)—tiny robotic aircraft that could potentially be used for surveillance and other purposes—is progressing in labs around the world. The California company AeroVironment has developed a hummingbird-inspired micro aircraft that weighs less than a AA battery, and other companies and research labs are currently looking into making even smaller autonomous aircraft. Better understanding how natural life evolved to fly in the rain, the researchers note, might help us design our own tiny crafts to stay aloft in the elements as well.

The 1991 Mount Pinatubo eruption, one of the largest in recent history, is dwarfed by the scale of supervolcano eruptions

About 74,000 years ago, in what is now Indonesia, Mount Toba violently erupted. The volcanic explosion sent some 700 cubic miles of magma into the air and deposited an ash layer roughly 6 inches thick over all of South Asia.

The eruption—which was an estimated 100 times larger than the largest in modern times, the 1815 Mount Tambora eruption—altered global climate patterns significantly, likely triggering a period of rapid cooling. The effect on ecosystems around the world was dramatic, and it may have nearly led to the extinction of the human species—some genetic studies suggest that the human population went through a bottleneck around that time, with as few as 1,000 breeding pairs of our ancestors surviving the devastating volcanic winter.

Yesterday, scientists from Vanderbilt University and the University of Chicago published a study in the journal PLoS ONE that has an ominous conclusion. Their findings indicate that the underground magma pools that fuel such supervolcanoes—pancake-shaped reservoirs that are typically 10 to 25 miles in diameter and one half to three miles deep—erupt much more quickly than previously thought. The research team says that once these enormous subterranean magma reservoirs form, they are unlikely to stay dormant for very long—they may be capable of sitting quietly for just thousands or even hundreds of years before erupting.

“Our study suggests that when these exceptionally large magma pools form, they are ephemeral, and cannot exist very long without erupting,” said Guilherme Gualda, the Vanderbilt University professor who directed the study, in a press release. ”The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.”

Hundreds of years may seem like a long time when compared to the length of a human life, but a century is just a blip when viewed in terms of geologic time. Most geologic events—the formation of mountains and the movement of tectonic plates, for example—typically occur on the order of hundreds of thousands or millions of years. So the fact that these underground magma pools can only lay dormant for mere centuries is stunning when viewed in the context of conventional beliefs about geology.

A rendering of the magma pool that fueled the Yellowstone supervolcano eruption roughly 2.1 million years ago

Gualda’s research team arrived at the conclusion by studying Bishop Tuff, a rock formation in eastern California that formed as a result of a supervolcano eruption some 760,000 years ago. Using advanced methods for analyzing the date of magma formation, the researchers concluded that the subterranean reservoir developed sometime between 500 and 3,000 years before the eruption. The resulting event covered more than half of North America with a layer of volcanic ash.

The potential effects of a supervolcano eruption in modern times are truly terrifying to behold. The eruption in Mount Tambora in Indonesia, which produced less than 1 percent of the volume of lava and ash of a supervolcano, caused 1815 to become known as “The Year Without a Summer” in North America and Europe. Volcanic ash suspended in the atmosphere blocked enough sunlight from reaching earth so that crop production was severely interrupted, causing famines and food riots in from Switzerland to China.

If the formation and eruption of giant magma pools capable of producing supervolcanoes truly happens as quickly as indicated in the study, it means we ought to take an entirely different approach in preparing for such cataclysms, the researchers report. Thankfully, it is believed that no magma pools of this size are present on earth at this time. But since they can form and erupt so rapidly, the authors recommend that we continually monitor geologic hot spots to detect the earliest signs of formation.

It might be impossible to prevent such natural disasters, but experts agree that preparation and advance warning are the best bet for mitigating the destruction they might bring. Centuries might be short when viewed in terms of geologic time, but they are long for human civilizations—long enough that, if we knew the location of a massive underground magma pool, we might even be able to intentionally avoid building cities and development in the area above it. This wouldn’t prevent the massive level of damage a supervolcano would bring, but it would reduce the destruction to some degree.

The microwave field around the objects without (left) and with the cloaking material (right). Image from "Experimental Verification of three-dimensional plasmonic cloaking in free space"

For years, science-fiction and fantasy authors have dreamed up magical objects—like Harry Potter’s invisibility cloak or Bilbo Baggins’ ring—that would render people and things invisible. Last week, a team of scientists at the University of Texas at Austin announced that they have gone one step further toward that goal. Using a method known as “plasmonic cloaking,” they have obscured a three-dimensional object in free space.

The object, a cylindrical tube about 7 inches long, was “invisible” to microwaves, rather than visible light—so it’s not like you could walk into the experimental apparatus and not see the object. But the achievement is nonetheless quite stunning. Understanding the principles of cloaking an object from microwaves could theoretically lead to actual invisibility soon enough. The study, published in late January in the New Journal of Physics, goes beyond previous experiments in which two-dimensional objects were hidden from various wavelengths of light.

How did the scientists do it? Under normal conditions, we see objects when visible light bounces off them and into our eyes. But the unique “plasmonic metamaterials” from which the cloak was made do something different: they scatter light in a variety of directions. ”When the scattered fields from the cloak and the object interfere, they cancel each other out and the overall effect is transparency and invisibility at all angles of observation,” said Professor Andrea Alu, co-author of the study.

To test the cloaking material, the research team covered the cylindrical tube with it and subjected the setup to a burst of microwave radiation. Because of the plasmonic material’s scattering effect, the resulting mapping of microwaves did not reveal the object. Other experiments revealed that the shape of the object did not affect the material’s effectiveness, and the team believes that it is theoretically possible to cloak multiple objects at once.

The next step, of course, is creating a cloaking material capable of obscuring not only microwaves, but visible light waves—an invisibility cloak we might be able to wear in everyday life. Alu, though, says that using plasmonic materials to hide larger objects (like, say, a human body) is still a ways away:

In principle, this technique could be used to cloak light; in fact, some plasmonic materials are naturally available at optical frequencies. However, the size of the objects that can be efficiently cloaked with this method scales with the wavelength of operation, so when applied to optical frequencies we may be able to efficiently stop the scattering of micrometre-sized objects.

In other words, if we’re trying to hide something from human eyes using this method, it’d have to be tiny—a micrometre is one-thousandth of a millimeter. Still, even this could be useful:

Cloaking small objects may be exciting for a variety of applications. For instance, we are currently investigating the application of these concepts to cloak a microscope tip at optical frequencies. This may greatly benefit biomedical and optical near-field measurements.

In 2008, a Berkeley team developed an ultra-thin material with the potential to someday render objects invisible, and earlier this year, a group of Cornell scientists funded by DARPA was able to hide an actual event 40 picoseconds long (that’s 40 trillionths of a second) by tweaking the rate of light’s flow.

Invisibility cloaks may still be years away, but it seems we’ve entered the Age of Invisibility.