Traditional medicine doesn't just fill up the health food aisle at the supermarket — it could help make everybody healthier. But how can we figure out which ancient herbal remedies actually work, and which ones are just hype? An estimated 10,000 to 53,000 plant species were traditionally used as medicines, and only some of those could have bioactive molecules with actual molecules. That's a lot of plants to sort through.

But now, a new study in the Proceedings of the National Academy of Sciences suggests that we can find out — by comparing the plants that multiple different cultures adopted as remedies.

Top image: Smoobs/Flickr.

For example, say a plant often used to cure headaches in an ancient Nepalese culture was closely related to a plant used for the same purpose in South Africa. The communication-crippling geographical distance between these two cultures indicates that they discovered their headache cures independently. So they probably began using these plants because the flora had real pain-killing abilities. This plant family may produce valuable bioactive compounds.

But studies attempting to analyze plants in this way face a tricky obstacle: that large geographical distance between the cultures also means that they don't share many plant species. As the scientists write in their paper, "The disparate regions that have experienced limited cultural contact are floristically disparate too, so different cultures will not be exposed to the same species, genera, or even families."

To get around this problem, the latest study ignored the system of taxonomy and instead directly compared plants' DNA. Researchers analyzed gene sequences from 20,000 plant species native to Nepal, New Zealand, and South Africa. Genetic differences between species helped the scientists reconstruct the plants' evolutionary relationships and place each species in its proper place on a type of family tree.

1,500 of the species studied were also used in traditional medicine. And the researchers found that these plants tended to cluster around the same sections of the tree, areas dubbed "hot nodes." Hot nodes also contained a significant number of known bioactive plants, which have already become the basis for modern medical drugs. When the researchers divided the traditionally used species into 13 categories, based on the type of ailments the remedies were supposed to treat, they found that plants in each category also clustered together.

The authors conclude that the plants near hot nodes on the cross-cultural plant family tree are more likely to have biological effects on the human body, and should become targets for drug development. "More than 80% of plant species have not been investigated for bioactivity and methods to distinguish those plants most likely to be bioactive when selecting species for further testing are needed," they write. "The finding that medicinal plant use shows strong phylogenetic clustering indicates targeting close relatives of plants with known bioactivity or phylogenetic medicinal hotspots identified as hot nodes is a good strategy for focused screening."

The dream of nanotechnology includes unbelievably tiny electronic devices — including medical devices that could work at the microscopic level. But how do you assemble nanoparticles into larger systems, like nanocrystals? You can't exactly use a pair of tweezers.

Instead, researchers create a solution of dissolved nanoparticles, which self-assemble into crystal structures. These nanocrystals –- which have a uniform structure and properties that can vary depending on their size –- may have a variety of applications. But to customize them, researchers need to be able to control their growth. And a good first step is figuring out how they assemble in the first place.

As the researchers write in their paper, published in the journal Science, "Understanding the mechanism of…nanocrystal growth using nanoparticles as building blocks provides a link between the world of single molecules and hierarchical nanostructures, and paves the way to rational design of nanomaterials with controlled properties."

How can you observe a nanocrystal as it grows? While any traditional optical microscope would fail miserably if it tried to focus at this scale, there are other imaging methods, such as transmission electron microscopy, or TEM. In TEM, the device sends a beam of electrons through an object and measures how the electrons interact with the sample. Then, an image of these interactions can be focused onto a film or measured by a camera.

But TEM needs its electron beam to travel through a vacuum, which means placing the sample under vacuum conditions. Meanwhile, nanoparticles need to be in solution in order to assemble into nanocrystals. Placing a liquid sample in the TEM vacuum would cause the solution to evaporate, destroying the assembly process rather than capturing its image.

Researchers at Lawrence Berkeley National Laboratory solved the problem by sealing their solution in a liquid cell. The scientists were studying platinum-iron nanorods, which can act as catalysts in electrochemical reactions. This makes them good candidates for inclusion in devices that store energy and convert it from one form to another. The nanorods self-assemble from a "growth solution" of platinum and iron nanoparticles dissolved in a solvent.

To create a liquid cell that could protect the solution from evaporation in a TEM's vacuum, the researchers stacked two thin transparent membranes of silicon nitride atop one other, leaving a gap only 120 nm thick between them. This gap was the right size to allow capillary action to suck the growth solution into the cell, leaving the solution sandwiched between the membranes. Finally, epoxy sealed the sandwich edges shut to close up the cell.

Another study in the same issue of Science used a similar technique to image nanocrystals assembling, but they were observing how two iron oxyhydroxide nanoparticles can attach to each other after they rotate to align their crystal lattices.

When the liquid cell of platinum-iron nanoparticles went into a TEM, this is what the scientists saw. These videos are sped up to run 30 times faster than real time. As time went on, the structures growing out of the solution became more and more organized. The nanoparticles began by forming long chains with multiple crystal orientations. Then the chains aligned, latching on to each other to form nanowires. Finally, the nanowires straightened out into long nanorods, 40 times longer than they were wide, with uniform crystal structures and orientations.

The paper describes in detail how the mess of nanoparticles grew more and more organized, eventually forming nanorods with a consistent crystalline structure:

"The nanoparticle chains formed during the early stage are winding and markedly flexible. The relative position of the nanoparticles within the chain changes and the orientation of individual nanoparticles also alters…During the final stage of growth, adjacent nanoparticles within the chain contact each other, forming a neck…Subsequently, mass redistribution eliminates the neck, and a smooth nanowire is formed. The diameter of the nanowire is slightly smaller (about 4.0 nm) than that of the individual nanoparticles before attachment (5.3 nm). A bent polycrystalline nanowire can straighten and transform into a singlecrystal nanorod with well-defined shape. This final stage of structural relaxation sometimes proceeds in parallel with the second stage of nanoparticle attachment. Notably, most of the nanowires remain twisted and polycrystalline for an extended period of time."

Knowing how these rods form will help scientists design nanomaterials with specific properties for a more effective, and perhaps tinier, future.

Via Science

Pancake artists, you need to up your game. Nathan Shields, an illustrator and former math teacher, is turning fried batter into an art form. In order to be a full-time dad, Shields is taking a break from teaching, but his math background — he still blogs about it at 10 Minute Math — is influencing his parenting. What else can explain his creation of edible fractals and mathematical constants?

Oh, you prefer biology? Then chow down on some marine invertebrates, or perhaps a few human organs. An archaeologist at heart? Try his dinosaurs. (Yes, I appreciate the inclusion of a chicken in that set.) Entomology? If Shields can detail the spines of a sea urchin, you better believe that he can cook up insects' legs as well.

And for the geeky cherry on top, take a bite out of Darth Vader. For more, including reptiles and dogs, check out Shields' website, Saipancakes. The name is a play on Saipan, the biggest of the Northern Mariana Islands (a U.S. Commonwealth located between Hawaii and the Philippines) and the one where Shields lives.

Via HuffPo

From Black Beauty to My Little Pony: Frienship is Magic, humans have an ongoing love affair with horses (and their smaller pony cousins). But not too long ago, the wild creatures that became horses looked considerably different.

Where did modern horses originate, and how did they become the domesticated species we know today? A new study sheds some light on the beasts of the steppes that became our most loyal mounts.

Top image: Vera Warmuth

In the past, different types of data have led researchers to reach contradictory conclusions about horses' origins. Archaeological remains have indicated that domestication occurred in one geographic location, around what is today the Ukraine and western Kazakhstan, and then spread out.

But at the same time, analysis of domesticated horses' mitochondrial DNA has revealed the DNA of multiple female ancestresses (as opposed to humanity's Mitochondrial Eve). Meanwhile, though, modern horses also lack diversity in the Y-chromosome, which seems to indicate that a small horse population was domesticated, and then those horses themselves spread across the continent.

So how did modern domestic horses start in one location, but with multiple lines of descent? Did the horses spread out from one location? Or did methods of domestication spread among humans in different areas, who tamed the diverse wild herds living near them?

A new study on the topic looks at Equus ferus, an extinct species that sired both domestic horses (Equus ferus caballus) and the wild Przewalski's horses (Equus ferus przewalskii) pictured above. Researchers took genetic samples from over 300 horses currently living east of the Ukraine in the northern part of Eurasian continent (the areas in color in map A) and compared their DNA. Western European horses were left out because they tend to belong to specific breeds, whose histories did not fit well into the model that the researchers were using. Based on the genetic variation in these horses, the scientists could reconstruct the basic structure of the extinct populations of E. ferus.

The researchers analyzed different scenarios for Equus ferus that had the horses originate in different parts of Eurasia. The red dots on map C are the possible locations of origin for the ancestral horses. The model that fit best with the genetic samples from modern horses suggested that E. ferus originated near the eastern dot about 160,000 years ago.

From the east, they moved across the continent and lived wild for roughly 100,000 years. Then, in western Eurasia — the Ukraine and western Kazakhstan — humans began domesticating Equus ferus, a trend that spread back again towards the east where the wild horses first originated. The blue dots on map D show the possible locations of first domestication that the researchers tested.

Although the genetic makeup of the animals in these domestic populations began to diverge from that of wild horses, there was still plenty of genetic mixing when wild stock was added to the herds. And the researchers suggest that rather than sneaky wild stallions mating with domestic mares, most of the wild genes came from wild females that entered a domesticated herd — which would explain the diversity of modern horses' mitochondrial DNA.

The researchers explain:

"In light of the exceptionally high levels of matrilineal diversity in horses, we suggest that introgression from the wild was mainly female-mediated. The repeated capture of wild females for the purpose of maintaining or growing domestic herd sizes may seem counterintuitive, given that in other domestic animal species, introgression from the wild typically involved domestic females being impregnated by wild males. However, given the initial difficulties in breeding the most closely related wild relative of domestic horses, Przewalski's horse, in captivity, it can be speculated that, for an indeterminate amount of time, herd sizes could not be maintained solely through breeding existing stock. Because stallions are inherently more difficult to handle than mares, the easiest way to maintain or grow herd sizes would have been to restock existing herds with wild females."

And why the low diversity in the Y-chromosome, which indicates fewer male ancestors?

"The observed low levels of Y chromosome variability might reflect the strong domestication bottleneck in western central Eurasia. Additional losses of patrilineal diversity may have occurred as a consequence of successive bottlenecks as domestic herds spread out of the western steppes and of breeding practices reducing the effective size of the male gene pool."

Via PNAS

To figure out how your brain works, researchers need to be able to measure the electrical activity of neurons. But now, a new method allows robots to perform the task instead.

Your brain and nervous systems are made up of neurons, sending and receiving the electrical signals that let us breathe, move, think, remember, and generally function. So knowing how individual neurons work, their patterns of electrical activity, and which of their genes are activated at any given time also will also give us insight into how the brain functions as a whole.

But how exactly do you crack open a neuron to analyze its activity? The current method of doing so is a highly specialized technique called whole-cell patch-clamp electrophysiology. In this method, you touch a hollow micro-pipette to the cell membrane of an individual neuron, as in the illustration. Gently, suck a tiny section, or "patch," of membrane into the tip of the pipette without rupturing the cell. Now, you can study the ion channels in that particular patch of membrane.

But let's be even more ambitious. The next step is to apply stronger suction, displacing your patch and leaving the pipette tip sealed to the outside of the cell. Through the open pore in the cell membrane, instruments can record the entire neuron's activity.

As you might imagine, patch-clamp is a fussy and difficult technique that requires months of training, limiting its practice to few laboratories. But what if you could automate the process? Instead of training humans to perform patch-clamp, labs could just order a robot programmed to do the job.

Researchers at MIT and the Georgia Institute of Technology have delegated whole-cell patch-clamp electrophysiology to a robot arm equipped with a cell-detection algorithm. The arm lowers the patch-clamp pipette into the brain of an unconscious mouse while measuring how easy it is for electricity to move out of the pipette. With no cells nearby, electricity flows easily, but when the pipette runs up near a neuron, the flow is impeded, allowing the arm to detect a cell. Under the guidance of an algorithm, the pipette moves along in two-micron increments, measuring the electrical impedance ten times every second and stopping as soon as the impedance shoots up, indicating the presence of a cell. Once it senses the cell, the robot arm can perform the patch-clamp procedure on it.

So far, the automated robot arm is great at detecting the cells, finding neurons 90 percent of the time, but it's not as good at performing the patch-clamp technique, only creating the connection about 40 percent of the time. Still, considering that humans can't get it right all the time either, the robot arm is pretty good at this technique, and it doesn't require a lengthy training process.

Based on their results, the researchers suggest that even more neuroscience could become automated:
"We have developed a robot that automatically performs patch clamping in vivo and demonstrated its use in the cortex and hippocampus of live mice. We anticipate that other applications of robotics to the automation of in vivo neuroscience experiments, and to other in vivo assays in bioengineering and medicine, will be possible. The ability to automatically make micropipettes… and to install them automatically, might eliminate some of the few remaining steps requiring human intervention. The use of automated respiratory and temperature monitoring could enable a single human operator to control many rigs at once, further increasing throughput."

While having robots examine brains for us would certainly be convenient, time-saving, and possibly more precise than human operators, I have to ask: Would you trust a bot with your own open skull? True, humans can make devastating mistakes without machine intervention, but the idea of one of our robot brethren cracking my head open still makes me a wee bit nervous.

Via Nature Methods

When it comes to Saturn's moons, Phoebe tends to be overshadowed by its siblings. Titan's size earns her the title of Saturn's biggest moon (and the second-biggest moon in our solar system), while Enceladus boasts those attention-getting fountains of water and ice pouring from its south pole. But new data from the Cassini mission shows that Phoebe might be more interesting than we thought, with a different origin and more planet-like qualities than Saturn's other moons.

NASA's Cassini-Huygens mission to Saturn has been collecting information about and images of Saturn's icy moons. And they started with little Phoebe, with a diameter of 140 miles, a fifteenth the diameter of Earth's own Moon. Unlike Saturn's other moons, which formed from the dust and gas surrounding the planet, Phoebe took shape out past the orbit of Neptune, in the Kuiper Belt. Within the first 3 million years of the solar system's formation, Phoebe had condensed into a dense, hot, spherical body with a rocky center. Phoebe is 40 percent denser than the average moon in Saturn's inner orbit, closer to the density of Pluto, which also lives in the Kuiper Belt. Many objects the size of Phoebe start out with irregular shapes, until collisions with other objects gradually bang them into spheres. But when NASA researchers used the Cassini images to model the history of Phoebe's craters, they concluded that the moon originally had a nearly spherical shape.

Phoebe formed quickly, and because it formed so early in the history of the solar system, it could have contained heat-producing radioactive materials, which kept it hot and possibly let it house liquid water. Cassini's fly-by also detected bright streaks, which are thought to be traces of ice, on Phoebe's surface.

Although the object remained warm for tens of millions of years and actively evolved for some time, it eventually froze up. Because it had formed so quickly, Phoebe could have continued to evolve into a planet. But since its development stalled, it's only the remains of a potential planet: a planetisimal.

A few hundred million years after it cooled off, Phoebe left its home in the Kuiper Belt and began drifting towards the inner solar system. As the it neared Saturn, the planet's gravitational field snagged Phoebe and it became one of Saturn's 60 moons. But its planetisimal status means that among those many moons, despite Titan's size and Enceladus's fountains, Phoebe remains unique.

Via NASA

Although tattoos and body piercings have gone mainstream, they still carry a connotation of risky behavior. And a new study suggests this stereotype is borne out in the drinking habits of those who modify their bodies: they drink more alcohol than their friends with undecorated skins.

For four Saturday nights, ninety-nine undergraduate business students in the west of France became temporary researchers. In four separate cities, they waited outside bars that catered primarily to college students, and surveyed youths as they left the drinking establishments. Almost 2000 subjects, 20 years old on average, told the interviewers how many tattoos and piercings they had, and underwent breathalyzer tests to determine how much alcohol they had consumed that night.

The study found that people with body artwork had more alcohol on their breath than those without. But the researchers also pointed out that in a previous study looking at tattoos and behavior, people who only had one tattoo tended to act more like their un-tattooed peers when it came to risky activities like drinking and unprotected sex. It was only when the researchers started looking at those with two or more tattoos that they noticed an increase in high-risk conduct. And it wasn't until the tattoo count hit seven that the risky behavior really shot up.

So if you see the Illustrated Man, can you assume he's an alcoholic? It's more accurate to say that tattoos and piercings go hand-in-hand with high-risk activities like excessive alcohol consumption - and this type of risk-taking also pairs well with being young. Many of those who get tattoos and body piercings are in their teens and early twenties, and this is also the age group that engages in more experimental behavior in the "high-risk" category, such as heavy drinking. So tattoos alone do not a drinker make – although they may mark a daredevil.

Via Alcoholism: Clinical & Experimental Research

In which international organization do delegates from Israel and Iran sit side-by-side in harmony? Hint: It's not the U.N. SESAME, or Synchrotron-light for Experimental Science and Applications in the Middle East, has united several countries in the quest to bring a light synchrotron to the Mid-East.

Top image of SESAME facility: SESAME.org.jo

In a light synchrotron, electrons race around a circular track, picking up energy, until they are charged up and ready to move into a storage ring. In this ring, the particles continue to move in a circle, generating the high-intensity light called synchrotron radiation, which then moves down various beamlines. Beamlines radiate from a storage ring like the rays of a cartoon sun, and each line contains mirrors and optical devices to control and adjust the synchrotron radiation, adapting it for specific applications. Because of the radiation's brightness and polarization, it is ideal for imaging various materials from crystals to proteins.

And having multiple beamlines means that many experiments can take place simultaneously at a single synchrotron. Facilities that include light synchrotrons, such as some of the Department of Energy national laboratories in the US, open their doors to scientists from all over the world who need synchrotron light for their research. But while Middle Eastern scientists can trek to the U.S or Europe if they need a synchrotron, having one close to home comes with its own benefits.

The term "brain drain" refers to the phenomenon where skilled workers and intellectuals leave poor countries in favor of more opportunities and a stabler environment in wealthier locales. For example, a scientist in Iran may choose to emigrate to America, where he or she could live near a synchrotron, as well as avoiding Iran's strict governmental restrictions. Although this move may be beneficial for the scientist, it prevents him or her from contributing to the knowledge and economy of her/his native country. By building a synchrotron in the Middle East, project SESAME could keep scientists in the region.

Not every Middle Eastern country has a serious brain drain problem. But most of the region does suffer from political instability, with both the recent revolutions of the Arab Spring, and also the traditional animosity between countries like Iran and Israel. Building a collaborative synchrotron, where scientists from all over the Middle East can work together, is a form of science diplomacy, allowing Iranians to meet Israelis on common ground.

This lack of animosity is unusual in Middle Eastern relations. "I was always curious about what a parallel universe was like, and know I know," says string theorist Eliezer Rabinovici, of Hebrew University. "I'm living in one when I go to SESAME meetings." And in this volatile region, forming friendships that transcend geographical boundaries can be vital. In a presentation at the American Physical Society (APS) March Meeting, Winick discussed how scientists can stand up for each other when human rights are threatened. Organizations like Scholars at Risk encourage researchers to help their colleagues who may be in danger from oppressive regimes, whether by dedicating a talk to the at-risk scientist or participating in a letter campaign.

Although the synchrotron is still under construction at its site in Jordan, user meetings for the project are already having effects. "Hundreds of scientists in the region have benefited from funding and from workshops," says Herman Winick, a SLAC physicist who, along with Gus Voss, came up with the idea for SESAME in 1997. The meetings are educational opportunities, and a chance for scientists to meet others who share their research interests. Israel and Egypt may have political differences, but SESAME user meetings have already yielded collaborations between scientists from both countries.

Still don't think that SESAME has enough going for it? It's also a chance for a little recycling. Synchrotrons are like iPhones – when a new version comes out, everybody wants to upgrade. As technology has advanced, synchrotrons have passed through three "generations," each providing better light than the previous one. And although it takes a lot more money and effort for a laboratory to upgrade its synchrotron than it does for you to purchase the latest gadget, it does happen – and then the labs ditch the previous incarnation of their synchrotron.

Take BESSY, a German synchrotron that started running in the 1980s. By the ‘90s, BESSY was no longer cutting-edge, and it was decommissioned in favor of BESSY II. Despite its former status as a multi-million Euro piece of scientific equipment, BESSY I would have been disassembled and sold for scrap. But Winick, who was on Bessy's board at the time, calculated that with some modifications, BESSY I could still produce x-rays up to the standard of modern synchrotrons. Winick and a few other European physicists suggested that with parts from other decommissioned accelerators, BESSY I could be reincarnated as the Middle East's own third-generation synchrotron.

The pieces of BESSY sailed to Jordan in 2002, and SESAME team members faced the tough task of building the facility to house the apparatus (the shielding to protect users from radiation was installed last year), reassembling BESSY with its added parts, and maintaining funding and political support for the project. UNESCO and non-Middle-Eastern scientific organizations have pledged support, as have some Middle Eastern governments. And in addition to funding, the participating countries can provide support and scientists, and the site: Jordan's proposed site had to defeat 17 other proposals from 6 other countries.

Although work continues on SESAME, as of the end of last year, members of the project estimated that it will be completed in 2015. And it could serve as an inspiration for more synchrotron-recycling projects for more facilities outside the US and Western Europe.

By the time you reach adulthood, learning a foreign language is a struggle – even after you memorize grammar and vocabulary, there's no guarantee that you'll understand a fast-talking native speaker, and when you stop studying for even a month, you seem to forget everything you'd learned.

Children's brains, on the other hand, are hard-wired to let them pick up languages with ease. Plus, a new study finds that even adult brains can re-wire themselves to mimic the brain patterns of native speakers – and this effect is amplified if they study by immersing themselves in a foreign language, rather than sitting in a classroom. And when they were not exposed to the new language for five months, their native-speaker brain patterns actually got stronger.

The new finding contrasts with previous studies, which indicated that similar levels of language learning could be achieved by both studying grammar rules in a classroom setting, or "explicit training," and immersion in the language, or "implicit training," defined as "training that engages…learners with the target language but does not provide any explicit information or direction to search for rules." But these studies failed to examine students' brains.

Researchers from Georgetown University Medical Center and the University of Illinois – Chicago used an artificial 13-word language, Brocanto2, to describe a computer game. While the artificial language's small vocabulary allowed subjects to learn it fairly quickly, its grammar was relatively sophisticated, mimicking the rules of Romance languages while diverging from the participants' native English grammar.

Next, the researchers separated 41 adults, who spoke only English, into two groups at random. One would study Brocanto2 through explicit, and the other through implicit, training. To standardize the brain scans, the participants all had to be right handed.

After studying and practicing the artificial language, the subjects listened to Brocanto2 sentences that were either correct or contained grammatical errors, and they had to press buttons to indicate whether the sentences were "good" or "bad." While participants underwent testing, EEG electrodes monitored the electrical activity on their scalps, which allowed the researchers to build a picture of their brain activity.

While both groups achieved similar proficiency in the artificial language, their brains weren't as evenly matched. Only the brains in the immersion training group processed language like native speakers' brains would. And even after five months of zero exposure to Brocanto2, the brain patterns in both groups only became more similar to those of native speakers.

"The results demonstrate that substantial periods with no [language] exposure are not necessarily detrimental. Rather, benefits may ensue from such periods of time even when there is no [language] exposure. Interestingly, both before and after the delay the implicitly trained group showed more native-like processing than the explicitly trained group, indicating that type of training also affects the attainment of nativelike processing in the brain."

Top image by Tobias Mikkelsen.

Via Journal of Cognitive Neuroscience, PLoS ONE

A raindrop is temporary, leaving behind a damp blotch and no more. Even if it falls in just the right area to create an imprint, even if that imprint is preserved for billions of years, it's just the imprint of a raindrop…right? Well, a fossilized footprint can teach archaeologists about the creatures who roamed the early Earth, but a fossilized rain imprint can tell us about the early Earth itself, and shed some new light on those scourges of global warming: greenhouse gases.

Top image: Mea Culpa Merlin / Flickr

A long, long time ago, it rained in South Africa. Specifically, it rained over volcanic ash, which preserved the imprints of the drops for 2.7 billion years. Researchers from the University of Washington analyzed these imprints to calculate the density of the Earth's atmosphere billions of years ago.

In their Nature paper, the scientists wrote, "We interpret the raindrop fossils using experiments in which water droplets of known size fall at terminal velocity into fresh and weathered volcanic ash, thus defining a relationship between imprint size and raindrop impact momentum."

To determine the velocity with which the droplets hit the ash, researchers made latex molds of the imprints and then measured them with a laser scanner. Once they knew the velocity with which the ancient raindrops fell, the researchers could compare it to the velocity of modern raindrops, and calculate how the density of the atmosphere back then differed from today's.

"We followed published methods to predict theoretically from first principles how raindrop terminal velocity changes with air density, and thus how dimensionless momentum changes with air density. Given the measurement of the largest Ventersdorp imprint, we obtained the corresponding dimensionless momentum of the impacting drop using our experimental relationship. By assuming the dimension of the raindrop responsible for the largest imprint (bounded by the maximum diameter of 6.8mm), we quantified atmospheric density."

While it's interesting to discover that the atmosphere billions of years ago was less than twice as dense as it is today, this finding actually helps clear up an ancient mystery.

More than four billion years ago, when the Earth and its sun were both young, the sun shone less brilliantly than it does today, and couldn't have kept the Earth as warm. In fact, the temperatures on Earth should have been low enough to freeze water solid, making life well nigh impossible.

But liquid water did indeed exist on Earth even during that cooler period over four billion years ago. In a 2005 press release from NASA, astrobiologist Carl Pilcher explains:

"NASA is interested in how early the Earth had abundant liquid water. If oceans form early in a planet's history, then so can life. Learning how early oceans formed on Earth will help us understand where else oceans and perhaps even life may have formed in this solar system and in planetary systems around other stars."

So what kept Earth warm enough to make water – and life – possible? Researchers had hypothesized that either the atmosphere was thicker and better able to seal in heat, or that greenhouse gases were at a higher concentration.

But this new paper proves that the atmosphere was not significantly thicker than it is today, so greenhouse gases had to be the cause. They may be causing trouble with global warming today — but life on Earth owes its very existence to the liquid water that greenhouse gases made possible billions of years ago.

Via Nature, image via Nature

What happens when you put snakes on a plane? No, not with Samuel L. Jackson – on a steep inclined plane. Generally, the animals will begin to slide down. But they can halt their fall by actively changing the positioning of their scales to increase friction. Knowing this has allowed robotic engineers to build better search-and-rescue robots whose "feet" function like snake scales.

Why snakes? "They're very cute and very easy to work with," Hamid Marvi, a Georgia Institute of Technology Ph.D candidate, joked at the American Physical Society March Meeting. More seriously, he explained how a snake's ability to crawl through narrow openings and scale heights makes it a "champion animal" that could easily navigate the site of a natural disaster. Robots that move like snakes could locate and bring aid to victims trapped in rubble.

Marvi and other researchers at Georgia Tech started out by studying how snakes' scales let them use anisotropic friction, or friction that is greater in one direction than another, to their advantage. For example, put a sleeping snake on one of those inclined planes. When you orient it so that it slips down head-first, the friction is twice as great as when the snake is oriented to slide down sideways.

This passive mechanism has to do with how the scales are layered on top of each other. You can feel the difference yourself: if you run a hand along a snake's belly from tail to head or side-to-side, the scales will hit sharply against your skin, but if you run your hand in the opposite direction, the scales slip smoothly past. Even the micro-structure of the scale is textured so that the coefficient of friction will be different when moving towards the snake's head or towards its tail.

Beyond the passive mechanisms, a conscious snake has even more control over its slide. "Snakes can actively control their frictional properties," explained Marvi. When an alert snake begins sliding down an inclined plane, its ventral muscles can modify the angle at which its scales hit the surface, increasing its friction.

And without scales to generate friction, a snake can't slither anywhere. The ability to move forward is dependent on the snake having a different coefficient of friction in different directions, which lets it push off of small bumps and rough patches in a rough surface. If you cover the snake's scales in a sock-like cloth "jacket," its friction becomes equal in all directions. The snake can still move its body in the characteristic S-like motion, but the wave doesn't drive the snake forward.

In addition to modifying the position of its scales, a snake can boost its speed by lifting segments of its body off the surface as it moves along. As its body twists into an S, the snake lifts up the curves of the S – removing any friction from the parts of the body that are moving sideways – while keeping the straighter middle segment in contact with the ground – increasing the friction on the part of the body that is moving forward.

To simulate a snake's motion on uneven ground, its scales must be taken into account, and that's exactly what the Georgia Tech team did. Based on their results, they created Scaly-Bot, a robot that can climb slopes. "You need to adjust the scales so you can grip with the substrate very well and the robot doesn't slide down the hill," Marvi says. By changing the angle between its scales and the surface, Scaly-Bot can adjust its friction and climb up.

And Scaly-Bot's successor, Scaly-Bot 2, has even more features, including steering, flexibility, and an accelerometer to sense when it's sliding so its scales can "sweep," seeking the correct angle to prevent further slipping. In fact, two of Scaly-Bot 2's eight motors are dedicated to controlling the angles of its "scales." Of course, a side effect of all these motors is that Scaly-Bot 2 is noisy and a bit ungainly. But then, the Georgia Tech team behind Scaly-Bot 2 is not a team of roboticists.

"Our focus is not on robotics, but on finding mechanisms to help roboticists develop more efficient robots," Marvi said. Further work is ongoing to turn Marvi's work into the materials and mechanisms that could let robots scale heights as easily as snakes do.

Scientists have made amazing progress lately in turning insects into cyborgs. Almost every week, there's another news story about cyborg insect first responders, or cockroach fuel cells. Soon enough, when someone plants an eavesdropping device in your house, it'll literally be a "bug."

Why do insects make such great candidates to become cyborgs? And what are we learning from cyborg insects that could help design better aircraft, or unlock the secrets of the human brain? We talked to the experts, and found out. Here's our complete guide to cyborg insects.

Top image: DM7 and iunewind/Shutterstock.com

So why do insects make such great candidates to become cyborgs in the first place? For one thing, they can move with a system of locomotion that's as sophisticated as that of most mammals. "The parallels in the control systems between arthropods and mammals is striking," says biologist Roy Ritzmann at Case Western University. Also, insects have open circulatory systems, and they recover quickly after surgery. But most of all, their locomotive and navigational abilities make them excellent cyborgs — and great templates for us to learn more about locomotion and flight in general.

People have the idea that insects are simple creatures, but Ritzmann says that's just not true. "It's not that insects are simple automatons that we can learn first and then apply to bigger animals." If anything, insects are just as complex and versatile as larger creatures.

So here are five things that we're learning from creating cyborg insects could transform the world we live in:

Living Batteries

Before you install machinery on an insect, you'll need a power source for the technology. Why not use the same energy that powers the insect's metabolism? In order for any organism to walk, wriggle, or repair its own cells, it has to transform the food it ingests into molecular energy. And when enzymes in roaches' bodies break down sugar, the final step of the process produces a handy byproduct: electrons.

Researchers at Case Western Reserve University inserted a wire into a cockroach to conduct these electrons and harvest the electricity. Although the cockroaches only produced a tiny current — one ten millionth of the current needed to power a 100-watt lightbulb — it could be gathered to power tiny electronic devices. Further work on storing the energy that cockroaches generate is ongoing, and if successful, could turn insects into live fuel cells.

Large insects like cockroaches are particularly well suited to electrode implantation. As Ritzmann, who contributed to the work, explains to us:

They've got an open circulatory system-the blood is not in high-pressure arteries. If you were to open up the brain of a mouse and try to implant electrodes, you'd have to maintain it on a respirator to maintain circulation to the brain. With a cockroach, if you open up the head capsule and keep it moist, then you can implant these things. Cockroaches will absorb a lot of damage to their nervous systems into their bodies and be able to function well.

In fact, roaches can function so well with their implanted hardware that they typically run away after they wake up from surgery. One spirited bug raced for freedom, jumped up, and broke $300 worth of equipment. Clearly, a living, moving battery isn't any good if it keeps running away. The next step to building a mechanical Frankenbug is to exert control over its motion-particularly if it can fly.

Flight Control

To control cyborg insects, you need to be able to steer their flight — which turns out to have all sorts of applications for aerodynamics in general. For example, it's easier to create a model for a beetle's wings if you can first watch the beetle flapping to a set beat. At Drexel University, Minjun Kim studies fluid mechanics, including how fluid air flows around the wings of a flying insect. In collaboration with Konkuk University in South Korea, he earned an NSF grant to look at the Japanese rhinoceros beetle, or Allomyrina dichotoma.

The grant abstract stated that Kim would conduct

an integrated investigation of the mechanics and control of beetle flight, using Allomyrina dichotoma as a model organism. The objective of the proposed research project is to understand the fundamental scientific principles that elucidate the wing folding/unfolding mechanism and govern the wing-wing interaction between the [forewing] and hind wing of a beetle during free-hovering flight, as well as to demonstrate the enabling technologies necessary to incorporate wing folding/unfolding mechanisms into flapping wing micro aerial vehicles.

To examine these wings and create accurate models, Kim and his collaborators used electrodes to control the beetle. "We have successfully implanted electrodes on the beetle," Kim explains. "Two electrodes were implanted on the left and right optic bulb, one on the central nervous system, and one on the pronotum, the backside of the insect."

By sending an electronic pulse into the beetle's body, Kim could stimulate it to flap its wings at a set frequency. A signal to the probes on the left or right optic nerves forced the beetle to skew left or right. In this video, the beetle flies to the left under the electrodes' influence:

Controlling the flight of this particular beetle also has non-cyborg applications. "They have extraordinary flight capability, such as vertical takeoff and landing," Kim says. If Kim and other researchers can quantify the mechanisms that help the Japanese rhinoceros beetle fly so well, then the Defense Advanced Research projects Agency (DARPA) and the Air Force might be able to reproduce its vertical takeoff and landing in aerial vehicles.

And in addition to reproducing the beetle flight, controlling it could turn the bugs into remote-control spies. Is it realistic to imagine a beetle carrying a tiny camera? Kim thinks so. "Depending on the size of the insect, they could have the load capability. A camera can be embedded as part of the head or body. You can do military surveillance based on wireless communication — that is the project that DARPA is working on these days."

But beetles aren't the only insects to fall under electrical control. A team of scientists from MIT, University of Arizona, and University of Washington successfully implanted a flexible neural probe, or FNP, onto the ventral nerve cord of a Manduca sexta, a tobacco hawkmoth. The probe was bi-directional, which meant that it could both send stimuli to and receive signals from the moth's central nervous system. A wireless signal forced the moth to skew left or right during free flight, while the receiving function let the probe transmit information about the moth's nervous system activity.

The researchers believe that neural probes could have wider applications. In their paper's abstract, they write, "These FNPs present a potent new platform for manipulating and measuring the neural circuitry of insects, and for other nerves in humans and other animals with similar dimensions as the ventral nerve cord of the moth."

Mind Control

"A lot of people have been implanting probes near the muscles controlling the abdomen," Ritzmann says. "If you could tap into the areas of the brain where the animal is making the command determining where it's going to go, you could do this a lot more subtly." Of course, this type of mind control would first require knowledge of how the brain sends these commands.

But one researcher is already exerting a different type of mind control over insects, and learning more about their brains in the process. At the University of Oxford, neuroscientist Gero Miesenbock uses genetic engineering, chemicals, and lasers to modify fruit flies' brains and behavior. After isolating the parts of a fly's brain responsible for certain behaviors, such as jumping, flying, or broadcasting a mating call, Miesenbock engineered flies in which these brain cells would be sensitive to light. Shining a laser at the flies from a distance was enough to stimulate these behaviors. Miesenbock even managed to make female flies enact a male behavior: vibrating one wing to "sing" a mating call.

And Miesenbock's mind control goes deeper than influencing behavior. He has also implanted memories into fruit fly brains. And in the process, he discovered the brain circuit responsible for the flies' memory formation. In order to make fruit flies avoid a certain odor, you could give them a shock every time they were exposed to that scent. The conditioning works because the insects form memories in which the smell is associated with pain. But Miesenbock bypassed this conditioning — instead implanting memories directly into fruit flies' brains.

Miesenbock injected the fly brains with nerve-signaling chemicals, which were programmed to target specific neurons. To prevent the chemicals from activating those neurons too soon, they were contained in a light-sensitive molecular trap. When the scientists exposed the flies to the odor, they shone a laser at the fruit flies, triggering the trap to open and the neurons to activate. If the targeted neurons were those responsible for memory, then they would trick the insects into associating the scent with a shock, despite the fact that there was no pain stimulus. Through educated trial-and-error, Miesenbock's team managed to identify the 12-neuron circuit that creates fly memories, and to implant the false memory of pain.

Better Robots, Stronger Brains

Cyborg insects could have a million uses — but they could also help us design better robots. And they could lead to advances in understanding our own brains.

Search-and-rescue robots find victims in conditions too tough to reach or unsafe for human rescuers, but they also get stuck and cannot extricate themselves. Cockroaches, on the other hand, easily navigate difficult terrain. Future robot designers could learn to borrow that ability.

"We've been spending the last 20 years or so looking at cockroaches trying to get around barriers and recording what's going on," says Ritzmann. "All of our work is geared towards trying to figure out how the nervous system solves these problems." Finding out how a cockroach's nervous system directs its motion tells researchers where to implant electrodes that would control the insect's movement. But it could also lead to smarter robots. "We work with engineers," Ritzmann explains, "who design robotic systems and controllers based on what we find." Robots could traverse a disaster site a lot more effectively if they're programmed to think and move like cockroaches.

And all that work studying insect brains may contain some insight into our own minds. Neural implants, like those that make a beetle flap its wings or a moth turn left on command, could also help the neuroscientists who study human brain diseases. "Many biomedical people study Alzheimer's," says Kim. "The idea is to implant a small semiconductor chip, then introduce a small electrical stimulation on part of the brain."

A 2011 study showed that electrical stimulation reduces the brain shrinkage that occurs in Alzheimer's patients, and improves their symptoms. Better neural implants, Kim claims, could help with this type of treatment. "Based on insect cybernetics, we can further develop this kind of stimulation, and give a high impact on Alzheimer research."

What about Miesenbock's work with fruit flies? While his research improves our understanding of how their brains work, could it also help us understand, and even control, more complex organisms? Not necessarily. After all, fruit fly brains contain far fewer neurons than do human ones. And insect cyborgs don't have to be stepping stones on the way to human ones — they're an end in themselves.

Images via Minjun Kim, 2 from Wikipedia

The United States hasn't always had the closest relationship with China or Russia. But give us a few hundred million years, and we could be a lot more unified: A new prediction for the motion of the continents suggests that the Americas and Asia will smoosh together at the north to form the supercontinent dubbed Amasia.

The concept of supercontinents is hardly new. About 300 million years ago, the supercontinent Pangaea included all seven of the continents we now and love today. But the upper part of the Earth's mantle, the rock layer between the crust and the core, is gooey enough to move. As it shifts, so do the tectonic plates above it, causing earthquakes in the short term, and relocating whole continents over millions of years.

The movement of tectonic plates eventually broke up Pangaea about 200 million years ago, just as it had broken up the previous supercontinent, Rodinia, over 500 million years before that. Geologists suspect that supercontinents may form, break up, and reform in cycles that last 500 to 700 million years. If so, then what supercontinent will cover Earth's surface in the future, and where will it be?

A new paper in Nature states that Amasia will form, as others have suggested previously, but the researchers have settled on a new theory for where it will be based on their new model, "orthoversion."

The authors wrote:

"Two hypotheses have been proposed for the organizing pattern of successive supercontinents. ‘Introversion' is the model whereby the relatively young, interior ocean stops spreading and closes such that a successor supercontinent forms where its predecessor was located. ‘Extroversion' is the model in which the relatively old, exterior ocean closes completely, such that a successor supercontinent forms in the hemisphere opposite to that of its predecessor. A third model, which we call ‘orthoversion', predicts that a successor supercontinent forms… orthogonal to the centroid of its predecessor."

If introversion occurs, then the relatively young Atlantic Ocean will close up and Amasia will form where Pangaea once sat. If the theory of extroversion wins out, then the Pacific Ocean will close and Amasia will settle down in Rodinia's old place, across the planet from Pangaea's former location. But according this new orthoversion model, Amasia's location will be at a right angle from both Pangaea and Rodinia: at the North Pole. During its formation, Amasia will close up the Arctic Ocean and the Caribbean Sea.

But don't count on Amasia just yet. Other theories predict that the continents will form a second Pangaea — dubbed Novopangaea, Pangaea Ultima or Pangaea Proxima. At least the geologists have plenty of time to figure it out, before it actually happens.

Via Nature, images via Mitchell et al / Nature

Australia faces serious ecological threats posed by feral animals and out-of-control wildfires. Non-native species gone wild have contributed to both problems, and one biologist is suggesting that Australia fight fire with fire by introducing more non-native species.

In an article in Nature, David Bowman, a biology professor at the University of Tasmania, lays out his vision for dealing with Australia's ecological problems. The continent suffers from wide ranging wildfires, which last year burned about five percent of the continent.

The fires feed on grasses, specifically a giant invasive species called gamba grass. Unlike most native weeds, gamba grass continues to grow during the dry season, making it an excellent source of fuel for intense flames.

Australia also has to deal with invasive fauna as well as flora: when domesticated animals like pigs, horses, buffalo, and camels escape or are released into the wild, they develop large feral populations. These mammals threaten the Australian ecosystem because of "the lack of any population control," explains Bowman. The once-domestic animal populations can increase quickly without warning, spreading into new territory and out-competing native species.

You might think that the feral animals could feed on the overgrown grasses and reduce the wildfires without human intervention. But remember the gamba grass? At up to 4 meters high, it's too big for these herbivores to handle.

Once Australia was home to huge animals called megafauna, which might have been able to control the grass growth and to out-compete the invasive herbivores. Just one glitch — the megafauna died out about 50,000 years ago in the Pleistocene extinctions.

Since then, the Aboriginal custom of patch burning, or setting small fires to burn off excess grass growth, has kept out-of-control fires from erupting, but this tradition has since been disrupted. Bowman suggests another way — importing large herbivores and predators:

I think that another, more holistic approach can address Australia's ecological problems. Specifically, we must restabilize food webs (now out of balance because of the Pleistocene extinctions), the loss of the Aboriginal traditions of patch burning and hunting, and the ad hoc release of non-native animals and plants. We must introduce and manage predators to control the feral animals, and bring in herbivore species to graze the flammable grasses - which we can better control using small fires as ‘uber-herbivores.'

Bowman's plan involves restoring traditional Aboriginal patch burning and hunting, and bringing in new animals to take care of the rest:

Indeed, existing ranger programmes that enable indigenous people to return to their roots - by hunting buffalo or managing natural resources - have been shown to have social and health benefits for this disadvantaged sector of the Australian community.

The paper Bowen cites is this 2009 paper published in the Medical Journal of Australia. Setting aside the uncomfortable notion that one group of people should do a specific kind of work, why should Aborigine buffalo hunting be any more effective than the type of buffalo hunting that Australians are already using in an attempt to control feral animals? Why can't non-native Australians learn to practice traditional patch burning methods? Bowman thinks that there are enough Aboriginal hunters to deal with the feral animal problem, but surely the more people who can help out with these environmental issues, the better.

And animals can help too: a key aspect of Bowman's plan involves introducing more non-native species in order to control the ones that are already there. Large herbivores like elephants and rhinoceroses could fill the void left by the extinct megafauna, chomping down on gamba grass to keep it under control, as well as competing for resources with the feral herbivores. Plus, this would serve the added purpose of protecting these animals from poaching in their indigenous homes.

Still, elephants in Australia? Bowman knows the suggestion sounds odd:

The idea of introducing elephants may seem absurd, but the only other methods likely to control gamba grass involve using chemicals or physically clearing the land, which would destroy the habitat…I realize that there are major risks associated with what I am proposing. It would be essential to proceed cautiously, with well-designed studies to monitor the effects.

To control the new species, Bowman takes inspiration from nature reserves. Selectively placed fences, a carefully controlled food and water supply, and a well-organized program of breeding and hunting would ensure that the introduced animal populations remained in check. Why couldn't these methods also work on the feral creatures? Bowman dismisses the idea because "the animals are too widespread to be controlled other than by shooting."

While letting large herbivores manage the grasses doesn't sound so bad, the notion of having predators tackle the feral animals may carry greater risk. In addition to Aboriginal hunters, Bowman indicates that native dingoes and non-native predators, such as Komodo dragons, could reduce the feral fauna's numbers. Instead of poisoning the dingoes, Bowman proposes that humans let the populations of these wild dogs grow so they can prey on the feral animal populations.

But there were good reasons that humans started poisoning dingoes in the first place. The Australian wild dogs scavenge from humans and can pose as much of a threat as obnoxious feral animals would. As for importing Komodo dragons to snack on the wild herbivores, Aussies may want to rethink a predator that "will eat almost anything...even...humans." These beasts are downright scary, even for a continent filled with threatening animals. Can we really come up with no better solution for eradicating feral animals than siccing even more dangerous creatures on them?

Via Nature, image via Brittany Hock/Flickr.

Sure, sugar's bad for you. But should we establish a drinking age for sugary sodas? According to UC San Francisco pediatric endocrinologist Robert Lustig, the answer is emphatically yes. He says that added sweeteners have health effects comparable to alcohol and tobacco, and should be regulated accordingly. In a comment piece for the journal Nature, Lustig and his colleagues argue that the state should selectively block access to sugar, using some pretty stiff rules.

For years, Lustig has advocated against added sugar, specifically sweeteners that include fructose. In the recent opinion piece, Lustig and his colleagues Laura A. Schmidt and Claire D. Brindis point out that fructose and other sugars can cause liver toxicity, among other chronic diseases. They write:

A little is not a problem, but a lot kills - slowly. If international bodies are truly concerned about public health, they must consider limiting fructose - and its main delivery vehicles, the added sugars HFCS and sucrose - which pose dangers to individuals and to society as a whole.

To restrict sugar, the researchers start with ideas drawn from existing alcohol and tobacco restrictions. They suggest establishing taxes on "sweetened fizzy drinks (soda), other sugar-sweetened beverages (for example, juice, sports drinks and chocolate milk) and sugared cereal." In addition, they advocate that we reduce the availability of sugar, particularly to children. This restriction would make it more difficult for vending machines to sell sweet drinks and sugary snacks in schools and in workplaces, building on already existing regulations that have removed sodas from some schools.

But there are even bigger steps to be taken in limiting the availability of added sugars. Lustig et. al. write:

States could apply zoning ordinances to control the number of fast-food outlets and convenience stores in low-income communities, and especially around schools, while providing incentives for the establishment of grocery stores and farmer's markets. Another option would be to limit sales during school operation, or to designate an age limit (such as 17) for the purchase of drinks with added sugar, particularly soda. Indeed, parents in South Philadelphia, Pennsylvania, recently took this upon themselves by lining up outside convenience stores and blocking children from entering them after school. Why couldn't a public-health directive do the same?

Refusing to allow fast food restaurants in certain areas? Banning children from convenience stores? I just can't see anyone accepting changes this radical. Do the researchers really think that people will sit back and let the government take away pastries, candy, and soda? Over our pudgy dead bodies. Surprisingly, the researchers don't see sugar cravings as their biggest obstacle.

They write:

Regulating sugar will not be easy - particularly in the ‘emerging markets' of developing countries where soft drinks are often cheaper than potable water or milk. We recognize that societal intervention to reduce the supply and demand for sugar faces an uphill political battle against a powerful sugar lobby, and will require active engagement from all stakeholders.

So the scientists think the biggest problem with regulating sugar is the sugar lobby*. But even without the lobbyists, would people ever cede their right to eat sweets?

Though sugar undoubtedly causes disease, I have a hard time accepting that we'll see the establishment of sugar regulations. And it's not just because the populace would rise up in protest.

One impetus for tobacco and alcohol regulations is protecting others. Tobacco can cause cancer in the smoker and those who are exposed to second-hand smoke. Alcohol is not only an addictive substance that can poison the body in large enough quantities, but also impairs judgment to the point where a drinker might, say, get into a car and plow into another vehicle or a pedestrian. The government doesn't regulate these substances just to protect the smokers and drinkers, it does so to protect others from the smokers and drinkers. Unless we discover that sugar hurts the people who watch us eat it, strict restrictions may be a long time coming.

Via Nature

*Not to be confused with a candy-filled receiving room, the sugar lobby is actually very powerful. Even if it's hard to take seriously when you picture the lobbyists working out of gingerbread offices.

Photo by RDaniel via Shutirstokk

It's a central tenet of evolution: Life must adapt to its surroundings or die. And the genome knows it. A new study published in the journal Nature shows that in more stressful surroundings, a yeast cell's genome actually gains or loses chromosomes, improving the cell's ability to mutate - and thus its adaptability. This mechanism could explain how some cancerous cells manage to survive the poisonous onslaught of chemotherapy.

Top image: NASA

Scientists from the Stowers Institute for Medical Research exposed yeast to stress-inducing chemicals, and then examined their chromosomes. When a yeast cell reproduces under normal conditions, cellular mechanisms kick in to make sure that chromosomes are transmitted carefully to the daughter cells. Under stressful conditions, however, these mechanisms broke down, with daughter cells sometimes losing a chromosome or gaining a superfluous one, and passing this abnormal genome down to their own descendents.

But how can a cell thrive when it's missing whole chromosomes? After all, chromosomal instability, also known as aneuploidy, is most frequently encountered in cases of cancer, developmental defects, and poor cellular health. But yeast may be the exception to the rule, with abnormal numbers of chromosomes found in both the yeast in your kitchen and the wild strains outside.

An earlier study had found that the yeast with an odd number of chromosomes could actually survive stressful conditions better than their normal counterparts. Creative mutations occur more readily in the abnormal cells, allowing them to evolve and adapt to the dangers of their environment more quickly.

Based on these earlier results, the researchers decided to see if the stress itself was inducing the chromosomal instability that allowed yeast to resist the stressors. Exposure to a variety of yeast-harming chemicals provided stressful environments for the yeast, which responded by losing and gaining chromosomes at ten to twenty times the usual rate of chromosome loss. And specific chromosomes led to protection from specific drugs. For example, yeast exposed to fluconazole, a drug used to eradicate yeast infections and meningitis, usually evolved into resistant colonies with an extra chromosome VIII, while those colonies that evolved to resist the fungicide benomyl tended to have no chromosome XII.

Interestingly, it didn't take much stress to cause aneuploidy. The yeast were exposed to protein-inhibiting radicicol at a very low concentration, so low that it barely slowed cellular growth - but it was still enough to create chromosome instability, which allowed radicicol-resistant yeast colonies to evolve. This resistance came in handy in more than one environment: When exposed to other anti-yeast drugs, the radicicol-resistant yeast could still survive more successfully than yeast cells that started out with a normal complement of chromosomes.

Aneuploidy may help the yeast survive stress, but it's not an ideal condition. Researchers took yeast that had lost chromosome XVI when exposed to tunicamycin, an enzyme inhibitor, and grew it in a drug-free environment. Without the stress of the chemical, the yeast developed into two separate colonies: one with cells that had lost a chromosome XVI and one whose cells had regained the chromosome to revert to a normal yeast genome. The colony that had regained the chromosome grew faster than its chromosome-missing counterpart. It had, however, lost its resistance to tunicamycin.

For yeast cells in a healthy environment, cells with a normal, stable number of chromosomes are more fit than those with aneuploidy. But under stressful conditions, the aneuploidy helps yeast outlive its normal counterpart. Plus, the fact that losing chromosome XVI led to tunicamycin resistance, while reverting to the normal number of chromosomes came at the cost of the drug resistance, indicates that the aneuploidy was directly linked to the drug resistance.

As the researchers write, "These findings demonstrate that aneuploidy is a form of stress-inducible mutation in eukaryotes, capable of fuelling rapid phenotypic evolution and drug resistance."

If stress itself causes the chromosomal instability that lets cells adapt to the stressful chemical, this could explain how cancer resists chemotherapy treatment. The toxins in chemotherapy can kill cancer cells, the way that a fungicide can kill yeast cells, but if the chemo drugs also trigger the cancer cells to lose or gain chromosomes, the tumor may be able to adapt to the stressful environment and survive the chemotherapy. To avoid this situation and make cancer treatments more effective, further research should explore the link between stressful environments and faster adaptation.

Via Nature

Picture a pigeon: gray body, iridescent neck feathers, probably pecking away at trash on a city sidewalk. But there are actually more than 350 different breeds of pigeon, and many of them look nothing like the familiar city pest. A new study examines the physical and genetic differences between the pigeon breeds, to come to some interesting conclusions about how appearance relates to genetics.

Top image: Harlan Harris/Flickr

Researchers at the University of Utah catalogued the physical traits and genetic codes of over 300 pigeons belonging to 70 different breeds and 2 free-living populations. There were plenty of physical differences to describe: "Domestic pigeons are spectacularly diverse and exhibit variation in more traits than any other bird species," they write in their Current Biology paper. At pigeon shows (yes, those exist), breeders from across the globe helped provide birds for DNA and feather sampling.

Surprisingly, some of the breeds that look different are close relatives genetically. Take the two closely related breeds of the English pouter pigeon and the Brunner pouter pigeon. The English breed, pictured on the left, has feathered feet, while the Brunner's feet, on the right, are scaly.

Breeds that share traits, on the other hand, are often more distantly related. In this image, both birds sport ornaments that look like Elizabethan neck ruffs. Despite sharing this feathery ornament, known as a head crest, the bird on the left is an old Dutch capuchine, which is not closely related to the komorner tumbler on the right. And other pigeon breeds with relatively little genetic similarity share feathered feet, or short beaks.

So why do the same traits keep cropping up in distantly related breeds? The answer lies in human hands. According to the researchers, "In The Origin of Species, Charles Darwin repeatedly calls attention to the striking variation among domestic pigeon breeds - generated by thousands of years of artificial selection on a single species by human breeders."

Because some human breeders thought that feathered pigeon feet were the hottest thing since curly dog fur, they bred selectively for that trait in both the Pomeranian pouter pigeon, whose feet are pictured in the top image, and the distantly related ice pigeon below. And although this form of trait selection is artificial, it's a good example of how evolution works. For example, this independent development of the same trait in multiple different genetic lines, known as convergent evolution, can also occur without human interference. In fact, Charles Darwin used pigeons to describe how selection influences the traits of a species, and as a model for how natural selection can lead to different traits in wild populations.

Despite their careful breeding, when pigeon populations become free-living - either in cities or in the wild - they evolve out of their original appearance. But DNA doesn't lie, and it revealed that racing pigeons have contributed a lot of genetic material to these populations. Studying an urban pigeon population in Salt Lake City, the researchers discovered that they are closely related to a breed of racing birds called racing homers, making them less "rats of the sky" and more "flying greyhounds." And a wild population in Scotland was also descended from an old racing breed that today is a show pigeon.

Like domestic dogs or tulips (check it out - not all of them are red or yellow cups), pigeons look incredibly diverse. But as this study shows, variation in appearance can have little relation to genetic differences.

Via Current Biology, images by Mike Shapiro, University of Utah

You probably think of your nervous system as a kind of computer network, or some kind of electrical system that passes nerve impulses around. But in reality, the miraculous journey of a signal thorough your nervous system is a story that involves cell biology, chemistry and physics. Your brain contains 30 billion neurons, and each of them is a staggering achievement.

Here are the secrets of how your nervous system passes messages with amazing speed and accuracy.

Top image: Case Western Reserve University

Neurons are unique-looking little cells. Like all animal cells, a neuron has a cell body, called a soma, where the DNA-carrying nucleus sits, providing directions for the cell to make various proteins. In a neuron, however, this is just the beginning of the cell structure. On one end, the soma sprouts branch-like dendrites for receiving signals, while a long –- up to a meter long –- axon stretches away in the other direction, branching out into multiple axon terminals for sending signals.

These axon terminals are often located close to the dendrites of another neuron, forming a connection known as a synapse — despite the fact that the axon terminals do not physically touch the other neuron's dendrites. Any given neuron will have about a thousand synapses with neighboring neurons, connecting the cells and allowing them to send messages from neuron to neuron. The synapses in a single human brain outnumber the stars in the Milky Way.

But if the synapses are empty space, with no direct connection between one neuron's axon terminals and another's dendrites, then how does the message travel? The cells must send chemical signals across the gap. Within each axon terminal are sacs, known as vesicles, filled with one of 50 different chemicals called neurotransmitters. Each neurotransmitter sends a different type of message to the next neuron, which recognizes the neurotransmitters with specialized receptors on the surface of the dendrites.

These receptor sites are like locks that can only be open by specific neurotransmitter keys. Once these keys have opened the lock, they drift back into the space between neurons, where they are either destroyed by enzymes or pumped back into their original neuron's axon terminal by transporters. Back inside the cell, the neurotransmitters are again either destroyed or returned to a vesicle where they can be reused. Different neurotransmitters serve different functions, and they are also recycled differently.

When the neurotransmitters fill the receptors of the receiving neuron's dendrites, they can either be excitatory (encouraging the receiver to pass the signal on), or inhibitory (preventing the receiver from continuing the message.) Any individual neuron's dendrites might receive neurotransmitter signals from one of many other neurons — and if the excitatory signal is strong enough and then inhibitory signal is not, it triggers the receiving neuron to fire, passing the message on.

Although chemicals are required to send a message from neuron to neuron, it takes a different medium to transmit that message from the receiving neuron's dendrites to its own axon terminals: electricity. When the neurotransmitters trigger the receiving neuron to fire, it sends an electrical "action potential" along its length the way that an electrical pulse flows down a metal wire. Like wires, some axons even have an insulating coating, the fatty myelin sheath, to make the signal travel faster.

So how does a clearly non-metallic human cell manage to conduct an electrical signal? The neuron has to alter its own charge relative to the outside of the cell. In order to change its charge, a neuron manipulates the charged ions on the inside and the outside of the cell membrane. When the neuron is at rest, with no signal in the pipeline, the ions are distributed so that the inside of the cell is more negatively charged than the outside, which creates an electrical potential, called the resting membrane potential, across the cell membrane. Sodium and potassium channels in the cell membrane control the flow of positively charged sodium and potassium ions into and out of the cell, maintaining that negative rest charge.

But when certain neurotransmitters have entered the receptor sites, it changes the makeup of the axon's cell membrane: In the section of the axon closest to the soma, the cell membrane becomes more permeable. This allows positive sodium ions to enter the cell and give the inside of that section of axon a positive charge relative to the outside. Although the sodium pumps work to move these positive charges out of the neuron and restore the resting state, the influx has already triggered the same behavior in the neighboring section of the cell. Gradually, this positive charge on the inside of the cell moves down the length of the axon to the axon terminals.

When the signal reaches the axon terminals, the electrical charge changes once more: instead of sodium ions, it is the positively charged calcium ions that enter the extra-permeable cell membrane. In the axon terminal, the arrival of calcium triggers the vesicles filled with neurotransmitter to drift to the cell membrane, fuse with it, and then release the appropriate neurotransmitters outside the cell. Although this process seems lengthy, an action potential moves incredibly quickly. If you had an axon the length of a football field, a fast action potential could traverse it in one second flat.

And then the next neuron in the chain has to repeat the whole process.

Further reading
In depth overviews from the University of Florida and the National Institutes of Health
More details on neurotransmitters from the University of Texas at Austin
More details on the action potential from the University of Washington and the University at Buffalo
A history of our knowledge of neurons firing by Francisco Bezanilla of the University of Chicago, published in the journal Neuron

Images via Medial Assisted Treatment of America and National Institutes of Health

Although dark matter's exact nature is still unknown, what we do know is that the amount of gravity in the universe is greater than the amount of visible matter that it corresponds to. This anomaly could be explained by some unseen source of extra mass, which provides the additional gravity that helps hold galaxies together. And the missing matter behind this extra mass has been dubbed dark matter.

Just as we surmised the existence of dark matter by detecting an abnormally large amount of gravity, an astrophysical instrument has detected an unusually large amount of radio waves coming from beyond this galaxy – and a new study is attributing those to dark matter as well, opening the door to new methods of dark matter detection.

Top image: Hubble Space Telescope/NASA.

NASA's Absolute Radiometer for Cosmology, Astrophysics and Diffusion Emission (ARCADE 2) is an airborne instrument that records, among other things, radio waves that originated outside this galaxy. Most of the signals can be linked to known extragalactic sources. But the ARCADE 2 team also discovered that known sources fail to account for an excess of radio waves in the frequency range between 3 and 90 gigahertz.

"The simplest explanation of such excess involves a ‘new' population of unresolved sources which become the most numerous at very low (observationally unreached) brightness," write the authors of a paper in the journal Physical Review Letters. They propose that the "unresolved sources" of these additional emissions could be a hypothetical candidate for dark matter called weakly interacting massive particles, or WIMPs.

How are WIMPs related to dark matter? As mentioned previously, the true nature of dark matter is unknown. Even astrophysicist Neil DeGrasse Tyson, in his recent profile, is quick to point out how little we know about it:

"But really we have no idea what's causing it. We so don't know what's causing it that we shouldn't even call it dark matter because that implies we have some understanding that it's matter. We don't know what it is. I could call it Fred. Eighty five percent all the gravity in the universe comes from something about which we know nothing…It's been with us since 1936 and it's one of the longest-standing unsolved problems in astrophysics."

Of the possible candidates for Fred dark matter, WIMPs are one of the most popular. We would expect a WIMP to be a relatively heavy subatomic particle, perhaps 40 times as massive as a proton, which rarely interacts with normal matter and then only weakly. (For example, once in a blue moon a WIMP might hit an atomic nucleus and make it vibrate slightly, and there are detectors looking for just that sort of interaction.) But we still aren't completely sure, since we have never actually detected a WIMP.

Nonetheless, based on what a WIMP should look like, the research team created a model for the radiation emitted by WIMPs – or rather, the radiation emitted by the secondary particles that are created every time that WIMPs decay or annihilate. They found that the expected WIMP emission closely matched the extra radio waves from the ARCADE 2 measurements.

Although the WIMPs could account for the unusual extragalactic radio signal, that does not necessarily mean that they are the true source. More research is required to even prove that the massive particles exist. But if they do produce these radio waves, it could help astrophysicists detect WIMPs without relying on gravity measurements, helping to reveal more about the true nature of dark matter.

Via the American Physical Society

Dogs make great companions – they're affectionate, adorable, and excellent listeners. But do they really know when we're talking to them? A Hungarian study tracked dogs' eye movements in order to monitor their focus of attention, concluding that the animals pay more attention to humans after being addressed directly.

Each one of 16 adult pet dogs watched a video where a human actor stood between two empty plastic flowerpots, greeted the viewer, and then turned to one of the pots. As the dogs watched, a video camera recorded the movements of their eyes to see if they would also look at the pot that the human was observing. A similar method has been used to test whether or not human babies who have not yet learned speech can still understand the intent to communicate. After all, current research suggests that dogs have a social intelligence similar to that of humans from half a year to two years old.

Before the human in the video looked at one of the pots, she greeted the dog in one of two ways. In the "ostensive-communicative" condition, she used the classic standby when greeting something cute: a high-pitched voice, direct eye contact, and a cheery "Hi dog!" (Both children and animals are more likely to respond to a high-pitched voice, which explains why we can't stop ourselves from cooing and babbling baby talk at cute creatures.) Under the non-ostensive condition, the actor opened the video with the same words, but spoke in a low voice and avoided eye contact. While the first scenario carries a clear message of direct communication, the non-ostensive one implies that the human has no intention of sharing information with the viewer.

After the communicative greeting, the dogs were more likely to follow along with the human gaze, a behavior on par with that of human infants. This behavior indicates that dogs can indeed tell when we are talking to them. It could also help reveal just how a dog's mind functions. As the paper states,

"Gaze-following behavior among humans is an early emerging pervasive response and is frequently considered as a window into social cognition of different nonhuman species. For instance, dogs have a robust ability to share attention with humans, and they are very skillful in using human gaze in object choice situations. Dogs are sensitive to the direction of human visual attention and are skillful users of human directional signals that have potential referential significance. Moreover, increasing evidence suggests that dogs show early and infant-like sensitivity to cues that signal the human's communicative intent."

Although these cues include both the communicative greeting's high voice and its eye contact, the researchers also point out that the dogs might be responding to these cues themselves, not to the communication that they represent. Specifically, the dogs might just be following the human gaze because of the initial eye contact and their own sensitivity to others' visual attention. The social environment in which pack animals like dogs – and primates – live requires that each member of the group have at least some awareness of what the others are paying attention to. The researchers say, "Besides the susceptibility to human ostensive cues, dogs' gaze-following behavior may also be considered as a socially facilitated orientation response with aspects linked to associative understanding of the net utility of the co-orientation with others."

So if you're hoping for a heart-to-heart with Fido, look him in the eye first. And don't forget your baby talk. Aaaww, who's a good boy?

Via Current Biology

If you've ever seen strange geometric patterns while on drugs, you might have wondered what on Earth caused you to see these hallucinations. What mechanism is behind this weird effect?

But a new study asks a different, equally reasonable question — not "Why do hallucinations occur?", but "Why don't they occur all the time?"

Top image: dimitris_k/Shutterstock.com

You rely on your visual cortex, located at the back of your brain, to process the images that you see. When light enters your eye, it stimulates certain parts in the visual cortex, forming a pattern of excited neurons, which you experience as an image. But once in a while, these excitation patterns arise spontaneously, overwhelming the visual signal from the eyes and causing geometric hallucinations. This "failure mode" only occurs when some influence, such as drugs, compromises your normal brain function.

The pattern of neurons that makes you visualize things that aren't there arises because of a type of self-organizing diffusion called the Turing mechanism, which contributes to the creation of patterns in certain biological and ecological systems.

As author Nigel Goldenfeld describes the mechanism:

"Normally we think of diffusion as a process which smooths things out. Think of an unequal density distribution in a gas. As the atoms diffuse around eventually the density becomes uniform. When you have diffusion occurring with nonlinear chemical reactions, however, the opposite happens. The chemical species separate and form domains of differing chemical composition. This was Alan Turing's surprising discovery."

These "Turing patterns" form in reaction-diffusion systems that contain two competing forces: an activator, and an inhibitor. For example, in a predator-prey ecological system, the prey are the activators, trying to reproduce, while the predators act as inhibitors, slowing the activators' rate of production. Goldenfeld says,

"Another system where Turing patterns arise is ecology. Instead of chemical reactions, you have interactions between species: for example, creature A eats creature B. If you take into account birth and death, predator competition, and the fact that birth rate depends on species density (if you ever had a long distance relationship, you'll understand where this comes from), you find that the equations governing the spatial and temporal distributions of species are the same as those describing chemical reactions. So you can get patterns of high and low species abundance. "

In the brain, the firing of a neuron can either encourage or prevent the firing of its connected neighbors, which means that neurons can act as both activators and inhibitors, making Turing patterns possible. In fact, the researchers suggest that if the visual cortex had a slightly different structure, the Turing mechanism would produce spontaneous neural patterns in it all the time, leading to permanent hallucinations. While this might be fun, it would barely let us see our surroundings. "There would be strong selection pressure against people who think they are seeing weird spiral patterns when in fact what is in front of their face is a hungry tiger!" explains Goldenfeld.

Instead, the researchers posit that the topology of the visual cortex does not allow the "inhibitor" signals to travel long distances, which is a requirement for the Turing mechanism. This prevents the Turing mechanism from working properly, giving neurons uniform diffusion patterns rather than geometric Turing patterns. Without the Turing mechanism to create interfering neural excitation patterns, the dominant patterns will be based on external stimuli: namely, normal visual signals from the eyes.

To test this hypothesis, the researchers created two models, one based on the actual structure of the visual cortex, the other a "physiologically plausible alternative network." The authors - who include Thomas Charles Butler, Marc Benayoun, Edward Wallace, Wim van Drongelen, and Jack Cowan, in addition to Goldenfeld - write,

"We show that the alternative network structures substantially degrade normal visual function, thereby illuminating the functional advantages of the network structure actually realized in [the primary visual cortex]."

When you take psychotropic drugs, disrupting your brain's normal activity, you may see geometric hallucinations like the image at left, which arose out of the alternative network. If your brain was normally structured like this, you might see a geometric pattern overlaying your vision at all times.

In the model of the real visual cortex, on the other hand, the Turing mechanism smoothes out, creating this even, uniform pattern, which could easily be overwritten by visual input. It would have been physically possible for the visual cortex to have developed into the structure of the alternative network. But natural selection prefers unclouded eyesight, evolving a visual cortex with the necessary constraints to prevent round-the-clock hallucinations… unless, of course, you've taken something to cause them.

Via PNAS

When left untreated, cancer cells begin migrating away from the tumor where they first developed, spreading throughout the body and becoming much deadlier. But what stimulates this migration? A new study suggests that physical cell compression – which occurs when a tumor grows in certain parts of the body, where there is limited room and the cancerous cells get squashed together – could be one of the impetuses for cancer migration.

In the early stages of cancer, cells stick around the location where they originated, a step referred to as in situ. The tumors become more dangerous when they move on to the invasive stage, growing into cell layers beyond their first location. From the invasive stage , cancer can metastasize and spread throughout the body, becoming even more deadly. "Most people who die of cancer," states the National Cancer Institute website, "die of metastatic disease."

In order to limit cancer's spread, it is important that we understand how it grows and why it changes from in situ to invasive and invasive to metastatic. This new American paper examined in situ cells under pressure, specifically, their behavior when they were compressed.

Researchers used a heavy piston to squash cancerous epithelial cells, which make up certain glands and line body cavities, against a membrane. In addition, they applied the same pressure to normal epithelial cells as a control. While maintaining the pressure on the cells, the researchers scratched some cells away from the membrane and looked at how quickly new cells migrated into the gap. In the cancer cells, the constant pressure from the piston acted as a stimulus for migration, as the cells at the edge of the scratch wound stretched out filopodia, or cellular "antennae," which are a key characteristic of many different types of migrating cells.

The filopodia-wielding cells on the edge of the wound acted as "leader cells" for the others, stimulating them to migrate more quickly than the non-cancerous control cells as the leader cells "guided" them into the cell-free scratch. The cancer cells also became clingier, bonding more firmly to the membrane. The increased migration and the enhanced ability to hold on to healthy tissues would both make the compressed tumor more deadly had it been in a real human body. In a similar scratch where the cells were not compressed, on the other hand, fewer cells on the edge of the scratch transformed into leader cells.

In a real tumor, the compression that cancer cells experience comes from growing in a confined area. The researchers suggest the cancer treatment take this pressure into account when attempting to prevent tumors from becoming more invasive:

"The concept of mechanical induction of tumor invasiveness could open the door to a unique class of targets for blocking mechanical stress pathways and guide the development of approaches for drug screening that take into account mechanical as well as genetic biological factors."

Via PNAS

This is not your father's pogo stick. Unlike the spring-driven toys many children use to bounce up and down, an extreme pogo stick can propel you over 8 feet into the air, leaving plenty of time for airborne spins, flips, and other tricks. How does it work?

"Tricks on pogo sticks have been around for a while," says Fred Grzybowski, a leading pogo athlete and an organizer of the extreme pogo movement. After all, pogo sticks were first developed and marketed as toys in 1918 – but the original tricks performed on them were hardly extreme. Traditional toy pogo sticks rely on steel springs to create bounce. When a rider lands on the ground, her weight compresses the spring, and as she pulls back up, the compressed spring recoils, helping drive her back into the air. This basic technology can barely propel riders a foot into the air. Even on adult-sized versions of the spring-based sticks, pogo riders had always had to skip daring tricks in favor of more technical performance pieces, such as balancing on a foot pedal.

With the advent of the internet, though, pogo riders could share these technical abilities, performing and taping stunts that they then posted online. Several pogo sites sprang up, providing forums and a community for sharing tricks. The smaller sites were eventually incorporated into the dominant Xpogo, the heart of the extreme pogo community. Xpogo's organizers also established the yearly competition Pogopalooza, which takes place in a different city every year, and the performance team The Pogo Dudes, who have appeared on a variety of American talk shows.

At the same time as the internet was bringing pogo enthusiasts together, researchers were ditching the traditional, easily breakable steel springs in favor of more powerful bounce impetuses, creating high-performance pogo sticks. Today's pogo sticks can propel their riders up to eight or nine feet high, providing air time for a variety of tricks and flips.

High-performance pogo sticks

"There's a blank canvas between the handlebar and the foot pegs to create bounce," explains Nick Ryan, a member of the Xpogo team and one of the organizers of Pogopalooza. Modern pogo manufacturers have found several new ways to fill in that canvas.

For example, one of today's most popular extreme pogo sticks, called the Vurtego, uses air — compressed air, to be precise. According to the official website,

"The body of the Vurtego pogo stick is a thermoplastic cylinder which is also the compression chamber for the air spring. It houses a piston and seal that are attached to a stainless steel slider shaft that extends out of the bottom of the pogo stick. A fill valve in the top of the stick allows the rider to add air to the cylinder to whatever pressure is desired. The higher the air pressure, the stiffer the spring."

Before mounting a Vurtego, riders fill it up to the desired pressure with a bike pump. Then, it can propel them over seven feet up into the air. Extreme pogo athletes use this height to leap over bars in high jump competitions, and to do flips and other tricks. But air isn't the only way of reaching new heights.

Grzybowski, for one, prefers the Flybar. "It has heavy-duty elastomers inside," he says. "Elastomers are big thick rubber bands. In my pogo stick I have up to 10 of them." When Grzybowski hits the ground on his Flybar, he stretches out the elastomers in the body of the pogo stick. Then, as he pulls up, the bands recoil, providing thrust to help him jump high into the air.

The elastomers provide a more gradual stretch than the abrupt recoil of steel springs, providing a smoother ride." According to Grzybowski. "It feels more like a trampoline." The Flybar's soft bounce has allowed it to retain some popularity among extreme pogo jumpers despite the fact that it breaks down more easily than the Vurtego: Riders are more likely to accidentally snap a rubber band than to somehow break down a column of compressed air.

The bounce of a pogo stick doesn't have to come from the inside. An external fiberglass bow drives the BowGo, developed by Ben Brown of Carnegie Mellon University's Robotics Institute since the late 1990s.

The bow-driven propulsion was originally used to create a bow-leg for a light robot, before Brown decided to scale it up and use it to power a pogo stick. As he says, "It just happened that we were building springy robot legs that were very efficient, so I decided to build a pogo stick using the same spring technology." In a BowGo, the bow replaces the traditional pogo's steel spring. When the pogo stick is motionless, the bow looks like a broad ribbon hanging parallel to the shaft. Brown explains, "The top end of the bow attaches to the housing up near where the handles are, and the bottom end attaches to the plunger that goes in and out of the housing." When a rider hits the ground, the plunger at the bottom goes into the shaft housing and the external bow flexes into a C. "As it bends, it stores elastic energy, and when it takes off, that spring energy is converted into vertical velocity, which sends the rider into the air."

Brown has handed over some of his BowGo prototypes to extreme pogo athlete Curt Markwardt. "He tries them out and sees what he can do with them," Brown says. Riding on a BowGo, Markwardt set a pogo high-jump world record in 2009, bouncing eight feet and 7 inches high. (That record has since been broken, and now stands at 9.5 feet.)

With input from Markwardt, Brown is continuing to develop his Bowgo prototypes in his spare time. Meanwhile, scooter manufacturer Razor has licensed the rights to the Bowgo design from Carnegie Mellon, creating a child's version called the BoGo, which cannot bounce as high as Brown's high-performance version. For the time being, the bow-driven pogo stick remains less common than the Vurtego and Flybar. But Brown doesn't mind - he's also busy using that same bow-leg technology for other purposes, such as the wall-climbing ParkourBot.

Making pogo extreme

"Extreme pogo sticks definitely fueled [the sport] to make it where it is today. There were tricks before that, but I don't know where my life would be if we didn't have high-performance pogo sticks," Grzybowski says. The heights that modern pogo sticks can reach are important for helping the extreme pogo movement overcome the idea that these sticks are just lame toys.

"[Extreme pogo] used to be a joke," says Ryan. "We used to be on the defense a lot." To overcome the stigma of pogo as toy, the extreme pogo movement has had to market itself. As Ryan explains, "We slowly built it through yearly touch points… At the first Pogopalooza there were six people in a parking lot in Nebraska." And the most recent Pogopalooza 8 included participants from across the United States, Canada, England, and Australia. In 2013, organizers hope to hold the tenth Pogopalooza in Times Square.

In addition to competitions, the movement's organizers aim to increase its public profile with performances from teams like the Pogo Dudes. Pogo athletes have performed in online videos, parades, busking, and on a variety of talk shows. Despite the increased publicity, pogo remains a fringe sport. "We want to make it a staple of the extreme sport world – but it's an uphill battle," says Ryan.

And in this battle, high-performing pogo sticks are perhaps the movement's greatest weapon, helping extreme pogo come into its own.

The closer we come to inventing a viable tractor beam - a ray of light that can move objects - the more obvious it is that real tractor beams will not look anything like the glowing blue rays from science fiction. So how will beams of light actually move matter? Let's find out by looking at three ways that scientists can already move solid objects using nothing more than light.

Photo via the Kansas Light Source

At the moment, development is ongoing on several different types of technology - and not all of them really deserve the title of tractor beam.

Take the laser thruster engine, which is activated by a laser beam, but moved by traditional propulsion. The concept is based on an experimental motor, where lasers fire pulses into solid propellant, shoving the propellant out of the craft in one direction to thrust the spacecraft the opposite way. With multiple propellants, the craft can be steered in different directions-and if the engine is modified to allow an external laser pulse to trigger the propellant expulsion, the engine can be steered by an outside source. With some modifications, these thrusters could be attached to space junk that needs to be pushed out of orbit, or even to an astronaut's suit so an adrift and unconscious astronaut could be steered to safety by shipmates.

Moving tiny objects with optical tweezers

But in a laser thruster engine, the laser itself is not pushing the object, merely triggering an engine that does all the work. Optical tweezers, on the other hand, actually move objects with the power of light alone. Although the photons that make up a focused beam of light have no mass, they do carry momentum, and when they hit an object and are forced to bend around it, their direction, and therefore their momentum, changes - which means that the object feels a miniscule force as part of conservation of momentum. In an "optical trap," a focused laser beam, more intense at the center, is pointed at a miniscule particle ranging from 10 to 100 nanometers long. As the particle deflects photons and they scatter around it, they also are holding it in place in an optical trap. By moving the laser beam, researchers can actually move the particle as well. These "optical tweezers" have been used to confine cells, track the motion of bacteria, apply small forces, modify cell membranes, and study molecular motors.

Moving larger objects using laser beams with hollow centers

Despite the many applications of optical tweezers, manipulating objects with lasers is a lot less cool when those objects are so small. Another technique improves tractor beams' abilities, moving glass beads a hundred times the size of the nanoscale objects that optical tweezers can push around. Rather than relying on the momentum of photons, this method uses their heat. A laser beam with a hollow center - two counter-propagating beams of light are overlapped so that they cancel out in the middle - is focused on a tiny glass bead so that the air around the bead remains cool while the air molecules farther away are heated by the laser and bounce around much more quickly. When the bead drifts into the hot air, it's like moving into a mosh pit of hot air molecules: the frenetic motion quickly pushes the bead back into the still, cool air in the center of the laser beam.

The bead can also be pushed along the length of the composite hollow laser beam by changing the intensity of the contributing lasers, heating the air on one side of the particle and pushing it along the beam with different velocities. This successful technique is estimated to be able to move small objects up to 10 meters in air - but because of its reliance on air molecules, it would not work in the vacuum of space.

Pulling objects with Bessel beams

Clearly, lasers can successfully push small objects along, but pulling them is another story. A couple methods deal with this hurdle by manipulating specific kinds of objects. For example, if the object can be induced to carry an electrical charge, the laser can drag it a short distance. But the most promising technology for pulling an object with laser light is that of Bessel beams.

While the cross-section of an ordinary laser looks like a filled in circle, the cross-section of a Bessel beam resembles a target, a set of concentric circles. The innermost circle of a Bessel beam also remains focused for longer than a typical laser would. Bessel beams can even travel through objects, rather than being stopped by them. All of these traits make Bessel beams ideal for tractor beam applications. For example, the increased focus of a Bessel beam makes it better suited for pushing on just part of an object, rather than the whole thing, increasing control of the object's movement. In addition, because a Bessel beam moves "through" objects, reconstructing itself on the opposite side, the light waves that make up the beam cannot only push the object, but they can also superimpose with a separate light source in order to build up more energy on the far side of the object than the near side, pulling the object toward the laser source. This nifty trick lets a Bessel beam both push and pull an object.

Although tractor beam technology continues to advance, it remains primarily limited to very tiny objects. So by all means, dream of tractor beams - just don't dream too big.

What's your earliest accurate memory? Chances are, it occurred after your third birthday, and until recently, scientists assumed that this was because children do not form accurate memories until the ages of three or four. But a new study from New Zealand suggests that children can correctly recall experiences from when they were two years old.

The general lack of memories before the age of three, dubbed childhood amnesia, has always had exceptions. An 1898 survey of earliest memories even found that 13 percent of the reported memories came from those early years. However, these recollections may not be genuine, but fabricated, actually coming from a different event, or reconstructed from stories told by adults ("remember that time Baby nodded off during dinner and fell face-first into her food?"). The doubt cast on young memories can disqualify some testimony from being used in court trials-but these early remembrances may in fact be true.

As the researchers point out in their paper:

"While these very early memories are not uncommon, their veracity is often debated. As researchers, what do we know about memory development that would allow us to establish an objective criterion for accepting or rejecting these accounts as genuine memories? Taken to the extreme, claims that some people can recall their own birth are generally met with great scepticism [sic], but is there any scientific reason to doubt the authenticity of these memories? What about other memories dating back to the first year or two of life?"

To test the veracity of early memories, a group of about 50 children between the ages of two and four played with a fairly memorable machine, which had an effect similar to being sent by TV: It "magically" shrunk objects. In their homes, the children turned on the machine with a handle of one color, inserted some large object into the top of the machine, and then turned a handle of a different color. With the ding of a bell, a door of a third color opened to reveal an identical object – except that it was a lot smaller.

The somewhat superfluous elements of the machine – having differently colored handles, the presence of a bell – gave the device specific features that researchers could later quiz the participants about, ensuring that they had formed accurate memories. To further assist in memory retrieval, all the children received distinctive cardboard medals after participating.

The researchers interviewed the participants one day after playing with the machine, quizzing them on specific aspects of how it worked, and then performed follow-up interviews again six years later. At the six-year interview, they also interviewed the participants' parents, as well as ten children who had never seen the machine, and who acted as a control group. (The way the control children responded to open-ended questions about the details of the "Magic Box" could be compared to the answers of the other participants, to see if any children were making up their memories of the machine.) After the taped interviews, "coders" read through the transcripts and rated whether or not the children really had remembered playing with the shrinking machine.

After 24 hours, all of the children remembered playing with the toy, but the quality of their memories depended on their ages. After six years, however, only eight children – twenty percent of the participants – remembered the machine accurately. Although a more impressive 62 percent of the parents could remember details about the "Magic Box," their memories were no more accurate than the childrens'.

And in an important detail, original age when children first encountered the shrinking machine did not affect their ability to recall real details about it – in fact, of the eight children who remembered the machine, two of them had been two years old when they first played with it.

The accuracy of the two-year-olds' memories indicates that they are capable of being decent witnesses in court. However, this does not necessarily mean that we should throw them into the witness stand. The study also found that children and parents who did not really remember the toy still answered some of the researchers' questions, sometimes guessing at the answers or in fact describing a different event, even though researchers specifically stated that it was fine for the answer to be "I don't know."

Via Child Development.

Photograph by Ami Parikh via Shutterstok