Our sibling publication Outdoor Liferesponds to our Dec. 10 feature on the anti-scientific laws that allowed 832F, the most famous wolf in Yellowstone, to be shot. We'll agree to disagree.

Today's ultrasound machines are a long way beyond just checking out babies in the womb--they're used to break up kidney stones, ease sore muscles and more. Now, with a new nanotube lens, they can also serve as an invisible sonic knife.

Though targeted ultrasound is useful, it can be unwieldy, with a relatively large focal area. Aim a beam of sound at a kidney stone and you'll likely hit the centimeter-sized object, but better precision--like hitting a cholesterol deposit in a blood vessel, or a specific clump of cancer cells--is hard to achieve. To improve matters, University of Michigan researchers turned to nanotubes and started with light instead of sound.

First Jay Guo and colleagues coated a specially designed optoacoustic lens, used to convert laser light into high-amplitude sound waves, with a layer of carbon nanotubes. The nanotubes absorb the laser light and grow warm as a result. The second layer was a rubbery synthetic material that expands when it gets warm. This serves as an amplifier. To produce the ultrasonic waves, Guo and his colleagues pulsed laser light through the 6-millimeter lens, which converted the optical energy into sonic energy. The graphene absorbed the laser's heat and the amplifier boosted the signal. The result were sound waves with a frequency 10,000 times the hearing capability of humans.

What's more, the waves were super-focused--the researchers controlled their target range from around 6 to 15 microns up to 300 to 400 μm.

Where other ultrasonic therapy uses heat to provide a stimulus, this one creates shockwaves that force pressure toward a target. Its superfine focus can blast away anything from blood clots to tumor growth--all non-invasively. In tests, Guo and colleagues detached a single cancer cell from an ovary and blasted a 150-micron hole in an artificial kidney stone. They say this type of ultra-precise ultrasound can be a new way to deliver drugs, fight cancer or even perform cosmetic surgery.

A paper describing their methods is published in Nature Scientific Reports. They plan to present their work at the upcoming SPIE Photonics West meeting in San Francisco.

[University of Michigan]

An ostrich-like dinosaur known as an ornithomimid would probably yield the most consumer-friendly cut of meat, while still maintaining a unique dinosaur taste.

Much of the flavor in a cut of meat comes from its fat composition, and an animal's diet contributes significantly to this. However, due to the average consumer's taste for meat that is not too strong-tasting, it is more important to figure out what we don't want the animals we consume to be eating. Dinosaurs that ate marine animals would definitely be off the list, not only for their fishy flavor, but also because the high amount of oil in fish would make the meat more susceptible to oxidation, which would give it a rancid taste. In fact, any carnivorous dinosaur would not fare too well in the supermarket. Most people prefer meat that comes from herbivorous animals-think cow, deer, bison- since animal fat found in a carnivore's diet adds a significant amount of "gamey" flavor. And some dinosaurs' diets are far too unappetizing to consider.

"When people ask me if a T-Rex would be good, well, I don't think so," David Varricchio, professor of paleontology at Montana State University, says. "They've found jaw abnormalities that suggests they were eating fetid meat and had diseases that came about from prey items. They would be pretty parasite-laden."

Just as important in the search for the best cut of dinosaur meat would be the level and type of activity for which the dinosaur was built.

As for exactly which dinosaur would be most appetizing, one with red meat would have just enough flavor as compared to one with blander white meat. Theories that dinosaurs would have tasted like chicken abound since dinosaurs are so closely related to birds, but for many land-dwelling dinosaurs, beef may be a closer guess. The kind of activity an animal does determines what kind of meat it yields. Red meat is composed of slow-twitch muscle fibers, which are built for sustained periods of activity, so animals that are active for longer amounts of time throughout the day would be composed of mostly red meat. Those who ambush their prey or move quickly for short periods of time would have white meat, which is composed of fast-twitch muscles that allow for quick bursts of activity. So dinosaurs taking part in extended periods of activity would probably have muscles less like a chicken (or even a fast-acting predator like a cheetah) and more like a steady-moving cow.

Ornithomimosaurs were a group of ostrich-like dinosaurs that were part of the suborder Theropoda from which modern birds evolved. They were close enough to birds that they likely had feathers and were warm-blooded, but they were very active animals with large hind legs for prolonged periods of running, so their muscles would probably have been mainly slow-twitch, less like modern birds. Though most theropods were carnivorous, ornithomimids were unique in that they had no teeth, a fact that has led most to believe they ate mostly plant matter.

"About 80 percent of the ornithomimids were hindquarters, and they were really well-suited for running," Varricchio says. "I've also done a little work on their bone histology and it's safe to say they're relatively fast-growing. I think it would be a lean, slightly wild-tasting red meat."

That's not to say other dinosaurs wouldn't make a tasty meal either. Velociraptors, being wild ambush predators, may have had gamier-tasting white meat comparable to a carnivorous bird such as a hawk. Taking into consideration activity level and diet could yield a huge variety of possibilities were dinosaurs ever to roam our pastures and grocery stores.

"You could get into cuts of meat. Armored dinosaurs mainly used their tails for defense, so that would probably be a lot of good white meat. Hadrosaurs were quadrupedal and spent much of their time on the move; I suspect they would be largely red meat," Varricchio says. Sauropods, the largest animals to ever walk the earth, may have made for an interesting meal as well. Their long necks, used to reach high-up food sources, could have resulted in a unique cut of sturdy red meat weighing several tons. Says Varricchio, "Sauropod neck could be a delicacy."

Florida native Erin Berger is a junior at Northwestern University. She is studying journalism and anthropology with a special interest in health, social justice and, of course, dinosaurs.

Thought experiment: What if you didn't know Barack Obama was president? Would you be able to spot him in a crowd--single him out as a leader? A new study suggests you might. Researchers at the University of British Columbia have found that people can identify leaders by sight--all it takes is about two minutes.

To figure this out, the researchers took a sample of 200 people, then broke them up into small groups and had them solve puzzles. The subjects then ranked each other based on who was the most dominant, prestigious, and influential in the group. After that, another group of 60 people was hooked up to eye-tracking technology and shown two minutes of the teams' problem-solving attempts. The watchers, researchers found, focused in on the person ranked the most dominant. (As an aside, likability didn't seem to affect where people looked, and "dominant" means "intimidating" more than "inspiring.")

Watching a group complete simple tasks together sounds like a fairly easy way to pick out the leader, so there's no telling how the situation would change at, say, a cocktail party. But if we really can determine the boss in two minutes, that's an intriguing find.

[University of British Columbia]

Try to spin these 3-D printed vinyl analogs at your next party, and the dance floor will likely grind to a halt. But the technique created by Instructables assistant tech editor Amanda Ghassaei for converting digital audio files into printable, playable 33 rpm records is actually pretty amazing, and as 3-D printer resolution continues ticking upward, the sound quality can only get better and better.

Printed on an Objet Connex500 printer capable of 600 dpi in the x and y axes, the vinyl analogs are reproduced using a custom-built program that essentially converts audio files into the CAD data necessary to reproduce the analog audio in the printed record grooves--a feat made possible by the relatively high-degree resolution now available in commercially marketed 3-D printers. This resolution is still an order of magnitude or two lower than the resolution of actual pressed vinyl--hence the lackluster sound you get from the 3-D printed records--but the fact that you can do it at all is impressive.

Ghassaei doesn't think the technique will ever be able to replicate true vinyl sound. Right now the 11 Khz sampling rate is roughly a quarter of what you get from the .mp3 that you're converting, and even at higher resolutions--which will produce better sound--it would be difficult to achieve the exact same sound. But that's not really the point. The point is that vinyl is old, and 3-D printing is new and combined they are very cool and interesting. And you can do it at home, if you have access to the right 3-D printing setup. Learn more about that at Instructables.

3D Printed Record from Amanda Ghassaei on Vimeo.

[Instructables]

In South Africa, conservationists have had to come up with new and more innovative ways to prevent poachers from killing the local rhinoceros for their horns. Enter the Rhino Rescue Project.

The trade in rhino horns is immensely profitable; rhinos are huge but not particularly hard to kill, since they need a lot of water and can be reliably found at watering holes. The horns are powdered and used in traditional Chinese medicine, prescribed for fevers and convulsions (not as an aphrodisiac, as is sometimes thought). So the Rhino Rescue Project began investigating something unorthodox: why not make the horns unusable as medicine?

There's a multi-pronged method here. Materials are not exactly injected but rather, as the Rhino Rescue Project says, "infused into the horn using a patented high-pressure device." No more detail is given about how that works. But the device uses a dye which turns the horn brightly and irrevocably pink, kind of like the dye used in ink packs to secure money at a bank. That makes it useless as a prize or ornament, and even if the horn is ground to a fine powder, it'll still show up in an airport security scanner. Three separate GPS chips are implanted into the horn, kind of like this older project--it's worth mentioning here that a rhino's horn is made of keratin, just like your fingernails, and the animal feels no pain during any of this. And the dye has no adverse health effects on the rhino.

In the future, the project even plans to add poison--ectoparasiticides, to be exact, which are damaging to neither the rhino nor any animal in the rhino's ecosystem, like ox-pecker birds. But for humans, it's pretty toxic, causing extreme nausea, vomiting, convulsions, and more. So: make it non-desirable to poach (by making it pink), make it hard to move (because it's pink, also because of the GPS trackers and the dye's visibility in scanners), and then make it useless for medicine (because it'll make you sick).

The project is still in the testing phase, but it's very promising stuff.

[via PSFK]

Before you read this column, I urge you to pop open a belated birthday beer. Pour that beer into a clear glass (pint or tulip, your choice), hold it up to the light, and take a good look at the color.

Two basic chemical reactions are responsible for beer being "beer-colored" rather than clear like water. One reaction couples amino acids to sugars; the other spurs sugars to decompose. In addition to adding color to beer, the products of these reactions also add significant flavor to the resultant brew.

A century ago in October, the Maillard reaction made its debut in the scientific literature thanks to the work of French chemist Louis-Camille Maillard. And the Maillard reaction is one of the most important reactions to understand how an amber beer looks different from a stout, which in turn looks different from a wit beer or pale ale.

The Maillard reaction is also known as "browning." When you toast bread or sear meat, that's the Maillard reaction. In beer making, kilning malted barley kicks off the Maillard reaction to produce darker malts such as Special B, chocolate malt and black patent malt. It and a process called caramelization are what gives roasted malts their characteristic caramel or toasty flavors, and beers such as stouts their characteristic dark color. (Long boil times will also spur these two reactions, so if you want a light-colored beer, make sure to keep boil times short.)

The Maillard reaction can be summed up as "amino acids react with a reducing sugar." There are many amino acids (the building blocks of proteins) and many sugars in malted barley, so hundreds of possible chemicals can result from this process. The basic reaction looks like this:

The Maillard reaction usually happens at elevated temperatures, but it has been known to occur at room temperature as well.

Caramelization, on the other hand, is a form of pyrolysis: thermochemical decomposition without the presence of oxygen. Basically: you heat sugar until it falls apart by itself. Again, there are many possible products of caramelization, but some of the main aroma compounds are furans, diacetyl and ethyl acetate. Caramelization only happens at elevated temperatures.

Here's how the various roasted, toasted, chocolatey, biscuity malts are made.

First, barley kernels are malted -- that is, they are allowed to partially germinate. During this process, some enzymes in the barley kernel break down the starches in the kernel's endosperm to free sugars such as fructose and glucose. During normal germination, those sugars would be used to fuel the spout's initial growth until it can start photosynthesis. But maltsters -- those people who malt the barley -- arrest the germination process shortly after it begins, by heating or drying the kernels. Depending on which kind of malt the maltster wants to make in the end, the kernels can be put into the kiln immediately, or they can dry the kernels first before kilning them.

In the case of the undried kernels, the maltster puts the green kernels directly into the kiln. The heat activates other enzymes in the kernel, and much of the starch in the kernel is converted to liquid sugar. Then the maltster increases the temperature of the kiln to between 220 and 320 degrees Fahrenheit; that's when most of the caramelization happens. The liquid sugar in the kernel begins to thermally decompose, creating compounds with buttery, or raisiny, or otherwise toffee-like aromas. How much and to what proportion those compounds are created depends on the temperature and duration of the roast. These end up as the so-called Crystal or Caramel malts that you might have seen in some of recipes BeerSci has presented.

[An aside: On the diagrams, I sketched just a few of the aroma compounds created by the Maillard and caramelization reactions, including 4-hydroxy-5-methyl-3(2h)furanone, which contributes fruit or jammy characteristics, maltol, which smells like cotton candy, and diacetyl, which gives the beer a buttery aroma. I say "dreaded diacetyl" on the graphics because this compound is one of the most common off-flavors in beer, the result of too-high fermentation temperatures or other brewing faults. A little diacetyl is OK; a lot can make a beer undrinkable. Team BeerSci just dumped a small batch of beer down the sink due to an overwhelming diacetyl component in the finish.]

Dried kernels, on the other hand, don't go through as much caramelization during kilning. Instead, Maillard reactions predominate, resulting in toasty aromas like, well, fresh toast, or chocolate or roasted coffee flavors and aromas. Toasted malts (those with toasty flavors from the Maillard reaction) such as amber malt, are subjected to heat of about 335 degrees F. Roasted malts, which have a mixture of Maillard reaction aromas and caramelization aromas, experience temperatures between 420 and 480 degrees F. Roasted malts include chocolate malt and black patent malt.

AND WHAT ABOUT THE COLOR?

The color that a malt contributes towards the final beer is typically indicated in degrees Lovibond. For example, Crystal 20 is a crystal malt kilned to a color that coordinates to 20 degrees Lovibond, and is lighter than Crystal 80. Most pale base malts such as 2-row barley are less than 5 degrees Lovibond. But because crystal/caramel malts are processed differently than toasted malts, Crystal 20 will have a very different character than a toasted malt that's also 20 degrees Lovibond. Further, within the dry-kilned toasted/roasted malts, the degree of toast or roast falls on a continuum. As far as I've seen, there's really no hard or fast line of demarcation as to what might be called a toasted malt versus a roasted one on the consumer side. You just have to read others' experiences with a particular malt (and each maltster might have their own quirks) and do the experimentation yourself.

To determine the color of beer, brewers use a different scale: SRM (Standard Reference Measurement), which is how much light at 430nm can get through 1 centimeter of beer in a photometer. Obviously, it's tough to use the SRM scale on a computer screen (unless it's color-corrected), but this is roughly what the SRM scale looks like:

The flavors created by the Maillard reaction and caramelization can be pretty strong, and can overpower a beer if the brewer isn't careful. That's why a lot of recipes, whose total grain bill might be over 10 pounds, call for only a few ounces of, say, black patent malt or Crystal 120.

To get an idea of how much color a small amount of specialty grain can give a beer, get a sample of Sierra Nevada's Celebration Ale. It's about a 12 on the SRM scale. For a five-gallon recipe of that beer, you would need 11.5 pounds of pale malt and only 1 pound of Crystal 35L. If you wanted to make a darker beer (say, 35 SRM) without changing the flavor significantly, add three or four ounces of debittered black malt.

At the other end of the scale, we just drank the first bottle of a Russian Imperial Stout -- a very dark beer with huge roasted, chocolate and burnt malt character, and high alcohol content -- we brewed a few weeks ago. According to the recipe source, it has an SRM of 129 (super-opaque black), but I haven't measured it myself, so take that with a swig of beer. Because this beer has such a high starting gravity, we only made 2.5 gallons of it. It's based on a recipe from 1914 of the Courage Imperial stout, highlighted by Ron Pattinson. We simply don't have a big enough mash tun and boil kettle to do a five-gallon all-grain batch of this beer.

Russian Imperial Stout
10 lbs. 12 oz. Maris Otter pale malt
2 lbs. brown malt (SRM 65)
1 lbs. black (crisp) malt (SRM 680)
3 oz. East Kent Goldings hops, divided into 2 oz and 1 oz batches
1 oz. Fuggles hops
Wyeast 1056

Mash grains at 153F for 120 minutes. Boil wort for 120 minutes. Add 2 oz. EKG hops after 30 minutes. Add another 1 oz EKG after 90 minutes. Dry hop with Fuggles for 14 days.

It's kind of amazing how many people are still upset about the supposed forthcoming end of the world tomorrow, which the government is supposedly hiding from us. Just to ease more people's apparently confused minds, the Slooh space camera is broadcasting views from our solar neighborhood in real time. Just in case.

Several seemingly sound explanations exist for the absurd notion that civilization will end tomorrow, Dec. 21, 2012, the end of the 5,125-year "long-count" Mayan calendar. These include a catastrophic solar flare related to the solar maximum; some kind of interaction with a black hole; a hidden second sun, or second planet called Nibiru, impacting Earth; and so on. The Slooh space camera, which broadcasts live telescope coverage of astronomical phenomena from telescopes in the Canary Islands, is addressing them.

To be clear, the Mayan calendar does not, nor did it ever, predict the end of the world. It's a page flip, from the 13th to the 14th baktun, the Slooh team notes. Like how you're getting a new 2013 calendar for the holidays, but you haven't put it up yet.

"Mesoamerican scholars insist the Maya never suggested such a calendar change would be apocalyptic, but Slooh will be on hand to scientifically either greet the uneventful arrival of Friday, or to bring live views of the end of the world," a Slooh news release reads. Slooh's coverage will include a global panel of scientists monitoring several observatories.

For instance, "Doomsday Scenario #2" holds that Earth will be hit by a near-Earth object, such as an asteroid or comet that the government is hiding from us. "Using our facilities, we will explore the night sky for unknown celestial activity," Slooh promises.

Scenario #3 holds that a gigantic solar flare will engulf our helpless rock. Slooh is linking to Prescott Observatory in Arizona, which is providing a world-class view of the sun in real-time and in true color. You can see it live here.

NASA has also taken up an aggressive campaign to convince people to not be so ridiculous. There's a nice curated list available here, with some appropriately caustic questions and answers. "If Nibiru or Planet X were real and headed for an encounter with the Earth in 2012, astronomers would have been tracking it for at least the past decade, and it would be visible by now to the naked eye. Obviously, it does not exist," NASA writes.

The agency also produced a cache of videos dated Dec. 22 and explaining "why the world didn't end yesterday," like this one:

All this reasoning has not convinced everyone, however. NASA's Facebook and Twitter feeds, which have been aggressively campaigning for the truth--that it's gonna be a boring day--are full of comments from people who truly believe something will happen. In that case, here's hoping Slooh's live views will calm people down.

With just a few days left until Christmas, my tree is barely holding on--to its needles, to its stiffness, and to its dignity. It was an early tree this year, the result of the earliest possible Thanksgiving, but it was more than that. There was something about this tree that made it dry out quickly, and make it less likely to keep its thin needles. It is a Fraser fir, Abies fraseriis, so this was a surprise to John Frampton.

Frampton, a professor in the department of Forestry and Environmental Resources at North Carolina State University, is the expert on Fraser firs, the most popular Christmas tree. Their conical shape, superb needle retention and sturdy boughs make them perfect for keeping both ornaments and tree bits off the floor. But Frampton is trying to make them even better, helping growers fight a worsening root fungus problem and to grow more trees more quickly.

As a result, Christmas trees of the future will be hybrids of different plant species, with parts borrowed and bred from the hardiest and most Christmasy species.

Fighting root rot

A Christmas tree spends six to 10 years in the field before it's cut, and trees usually aren't planted in tree plantations until they're at least two or three--meaning my Christmas tree was born when I was still in my teens. It turns out those early years of the tree's life were its most difficult.

Fraser firs have no immunity against phytophthora, a genus of damaging molds that cause plant roots to rot. Its Greek name means "plant destroyer," and it can decimate crops and almost any other type of plant--a phytophthora species caused the potato blight that sparked the Great Irish Famine. Frampton has tried to find resistant trees to breed, but to no avail.

"We grow seedlings in the greenhouse and we inoculate them to test their resistance; when we do that, we kill them all," he said. "We've tested a very genetically diverse population several times, and every time we test it, we kill the trees."

To make stronger trees, he has to perform a bit of vegetation vivisection. Frampton tested 32 of the world's 50-odd true fir species, and found a Japanese tree called the Momi fir strongly resists phytophthora invasion. They make terrible Christmas trees, so Frampton teaches tree growers how to borrow their roots.

He buys Momi fir seedlings and cuts off the tree part, grafting Fraser fir branches into their root systems. Grafting is a common horticultural technique to essentially clone different plants, but in this case it's making chimeric trees.

"We take a young seedling of Momi fir and cut the top off. Then we take a grafting knife, and make a vertical slit down the center. We take a Fraser fir branch and trim the base into a wedge, and we insert that into the Momi fir that we cut," Frampton explained. The newly grafted tree is wrapped in special rubber bands and covered in wax to keep it from drying out.

"Then the area between the bark and the wood, the growing point, merges. It grows together for the two species, and they form one functioning tree. The top of the tree is Fraser fir, and everything below the graft union is still Momi fir."

This is kind of expensive, however, and time-consuming. Tree growers would prefer seedlings that already have root-rot resistance, but maintain the ideal needle retention and pretty conical shape of Frasers. That's where genetics comes in.

Breeding tougher trees

When he was testing seedlings for root-rot resistance, Frampton went to Turkey and gathered cones from Nordmann fir trees, inoculating seedlings he grew in his greenhouse. Some of them can resist it, he found--activation of certain genes can control that resistance. That means Frampton and other growers can select trees that are naturally resistant to root rot, and breed them.

He's not making genetically engineered Christmas trees, however--at least not yet. Frampton's lab and other researchers are trying to determine the genetic sequences that code for ideal traits, from cone shape to root-rot resistance, and find markers for these sequences so they can be further studied.

"We are doing DNA sequencing to understand the DNA of Christmas trees, and in the long term, this may lead in the future to genetic engineering," Frampton said. "But there is still more knowledge and techniques we need to develop before we're to the point that agriculture is now."

That's partly because funding for genetic engineering of plants mostly focuses on the kind we eat, he noted. But it's also because breeding trees is difficult. Mostly it's because they're trees, and, well, trees don't grow like weeds.

"To see how well it grows, you need to wait six or eight years to see if it's the tree you want," Frampton said. "Once we find good trees, we want to cross them, but it takes firs 10 or 12 years before they become reproductively mature, before we can start making crosses among them. So the breeding approach is certainly long-term for improving Fraser firs for Christmas trees."

The trees are now big business in North Carolina, which is home to 2,500 tree growers producing 5 to 6 million trees a year. Fraser firs are native to Appalachia, especially the craggy peaks of western North Carolina above 3,000 feet in elevation. This chilly, rainy environment may have something to do with the quick closure of the trees' stomata, small respiratory holes on the needles, once they're cut. Fraser firs adapted to live in very wet environments, and they don't dry out like other firs and pines--another key feature that makes them ideal Christmas trees.

But still, every tree is unique, both in its individual history and circumstances. My tree, for instance, might have gone without water for weeks after it was cut, or maybe it lived through warm winters, which could have impacted the way its needles set. Or maybe it's just genetics. Frampton said he hopes future trees will be more reliable.

"That's why we are looking at needle retention and trying to understand how we can manipulate it through genetics," he said. "But we are also trying to understand how we can handle trees better, and teach consumers best practices to reduce the likelihood that they will have a messy Christmas."

THE DISEASE

For decades, the term "punch-drunk" has been used to describe boxers left permanently loopy after a career of fighting. The clinical name for the condition is chronic traumatic encephalopathy (CTE), and it can happen to any athlete who suffers frequent blows to the head. CTE has no known treatment, and doctors can only diagnose it postmortem, by physically examining the brain for symptoms.

WHAT CAUSES IT?

At its most basic, CTE is a cumulative effect from repetitive head trauma-not just concussive blows but also weaker ones. Impacts damage the brain's neural pathways, and as a result a protein called tau builds up. The more tau along the pathways, the less easily brain signals can move around, which can lead to memory loss, lack of impulse control, aggression, and depression.

HOW COMMON IS IT?

Scientists at the Center for the Study of Traumatic Encephalopathy at Boston University examine the brains of dead contact-sports athletes. In its first year of operation, 17 of the 18 brains researchers tested had CTE. Also, a team of scientists recently reported that former NFL players are three times more likely than the general population to die from brain diseases such as Alzheimer's.

WHAT DOES IT MEAN FOR HELMETS?

Because football helmet safety standards were designed to prevent skull fracture, padding has to be stiff enough to weather an extremely hard hit. But stiff cushioning allows a lot of force to reach the head. Over time, that can lead to CTE. Certain companies, such as Xenith, have begun to use adaptive cushioning. It stays stiff during a big impact, but softens during a smaller one.

This article appeared in the January 2013 issue of Popular Science. Read the companion feature "The Helmet Wars" here.

The world is definitely not going to end today. So don't worry. But! If you enjoy worrying, or just really want to be prepared for future apocalypses, then the March 1951 issue of Popular Science is required reading. In the middle of the Cold War, we published an eerily-illustrated handbook for surviving an atomic bomb strike, from preparing your family's foxhole to what to do if you're caught outside during the blast. Unfortunately, none of these preparations were likely to do much good if your neighborhood was actually hit by a nuclear bomb, but some of the advice might come in handy against mysterious Mayan voodoo (or whatever.)

To improve your odds of making it through the end of the world, view the larger version of the infographic below.

Read the full story, with way more helpful advice, in our March 1951 issue.

A study at Duke University sought to uncover the meaning behind the peacock's so-called "hoot dash" display. The hoot dash is a peculiar courtship move in which a male peacock emits a loud noise, something like the honk of a clown's horn, right before copulation. The female peahen is already ready for mating; why does the male need to let out this powerful squawk?

The researchers suspected that the male peacock is actually attempting to attract other females by boasting of his ability to snag one female. (I think there was a Seinfeld episode in which George attempted the same thing by wearing a wedding ring to attract women.) To test out this theory, the researchers recorded this "love honk" and played it back over loudspeakers for a group of peahens. And sure enough, the females approached that speaker much more often than a speaker from which some other sound (or no sound at all) was playing.

The big question now: why don't male peacocks just fake it? They could make that evidently attractive honk noise anytime they want, but don't seem to have grasped this amazing weapon they have at their disposal. Or maybe they just saw that Seinfeld episode. I don't think it worked out for George.

The study will appear in the January issue of Behaviour.

We've seen auto tech that's faster, smarter, safer and more eco-friendly than ever before in 2012. See our top picks here.

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Nowadays, many of us rely on online user reviews, instead of expert opinions or the advice of family and friends, for help making decisions both big and small. If we want to know about a restaurant, a hotel, a product--or even a neighborhood, a school district, a church, a donut shop or a barber--we tap the web and the massive database of reviews that populates it. Turns out those reviews are influencing us in ways we might not realize.

An Australian researcher conducted a pair of studies in which he found that positive reviews stay fresher in our minds than negative reviews. What's more, reading positive reviews early in our experience with a product or service will trump negative reviews that might come later--even if we're told the positive reviews are inaccurate or wholly untrue.

In the first study, 76 undergrads were given a slew of positive facts about a certain brand of coffee, and then presented with a bunch of negative talking points regarding a second brand. They were asked for their thoughts on each coffee brand, which correlated to the information that they had been given. But when a research assistant then told them that the sheets had accidentally been mislabeled--that the positive attributes actually described the negatively cast brand and vice versa--the positive ideas associated with the first brand still lingered, even in light of the new information. When asked to describe how they felt about the companies a second time, subjects gave a fair overall rating to the brand that was originally described negatively (and now positively). As for the brand originally described as good (and now bad): The impact of the earlier positive description lingered, and its overall score remained high.

A second test asked nearly 300 undergrads to read five reviews of a Los Angeles hotel. For some readers, the reviews were arranged from positive to negative; for others, negative to positive. Those who read the more positive reviews first had a far higher opinion of the hotel overall--even though the reviews were dated across the span of a year. That is, for the positive-to-negative group, it appeared the hotel had been slipping in quality over time, and for the other group it appeared the hotel had been steadily improving over time. No matter. The positive review, consumed early on, trumps whatever information comes later.

The suggestion: If something gets a few positive reviews early on, it's as good as gold in our minds. Something to consider next time you turn to Yelp for help picking a good Italian place.

[Research Digest]

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The Wiki Weapon project is an initiative undertaken by Defense Distributed, a non-profit headed by University of Texas law student Cody Wilson aimed at generating a freely-distributed, open source design for a 3-D printed firearm--an idea that has come under serious fire from proponents of increased gun control in the U.S., particularly in light of last week's tragic shooting of 26 people at Sandy Hook Elementary School in Newtown, Conn. The idea behind the project--embraced by some, absolutely detested by others--is that technology will soon make regulating firearms virtually impossible. That is a very polarizing idea. But to say the very least Wiki Weapons is also a technologically intriguing project, one that forces us to examine some very relevant--some might say ominous--questions about new technological capabilities and where they are taking us, as well as what happens when technology gets way out in front of the law. We spoke with Wilson briefly this week hoping to address some of these questions. Below is an edited transcript of that conversation.

Popular Science: It would be pointless for us to ignore the context in which we're speaking today, given the tragedy that unfolded in Connecticut last week. Defense Distributed has committed to creating a shareable, freely-distributed design for a working 3-D printed firearm--a way for anyone with a 3-D printer to quickly produce a working gun. Does an incident like this one in any way alter your conviction that this is the right thing to do?

"I tell people sometimes 'We're not making a Second Amendment argument.' The basic idea is to take a technology, play futurist, and surprise people."Cody Wilson: No, not at all. If it did change what we thought you'd be right to recognize that we're not serious. I don't want to be confrontational about it, but I will say it this way: understanding that rights and civil liberties are something that we protect is also understanding that they have consequences that are also protected, or tolerated. The exercise of civil liberties is antithetical to the idea of an completely totalizing state. That's just the way it is.

I heard Joe Scarborough say this, and this is a flagrant example. He said "I was a Second Amendment supporter but this has made me change my mind." Well, then you never really were serious about it.

You know, the jurisprudence of the Second Amendment has only just begun. The results that Second Amendment supporters have received from the courts are probably as good as they could've ever hoped for, but we're already off on the wrong foot. The court treats this civil liberty differently than every other right. It's amazing. Even the Supreme Court majority has displayed this weird calculus about social cost that assumes from the beginning that gun ownership is a nuisance that can be safe every now and then and has to be tolerated. This isn't how we treat any other right in the Bill of Rights--as a nuisance first. I've been thinking about this a lot lately. The presumption that it's just a bad idea to own a gun, that we have to subject ourselves to all of these things and jump through all of these hoops to own a firearm--it doesn't work that way with speech, it doesn't work that way for the Fifth Amendment, the Fourth Amendment.

This project is, as much as anything else, an immanent critique of Second Amendment-ism. We're demonstrating the difference between the promise and the practice of the access to firearms.

Where do you feel this project fits into the "gun control" conversation? What you're doing fits more into the maker movement than the traditional firearms industry paradigm. So when people talk gun control to you, do you see this project fitting into the same conversation?

Right, it doesn't fit into the regulatory framework for gun manufacturing. But of course it fits into the larger discussion. A reporter will ask me "what are you going to do to restrict access to the files?" Well look, you don't have to get a background check to check out a book from the library. We're not going to do anything to restrict access to the files. That's the whole point. The control would have to happen at the point of access to the information, and I just don't have that attitude about the restraint and censorship of information that the prohibitionists do.

Here's how the discussion demonstrates the difference in the argument. So-called "progressives," their only response is "ban it. Ban it, ban it, ban it--ban it here, ban it there, ban the future." It just seems so conservative all of a sudden. How are these people committed to civil liberties? I'm saying: "Look, of course this can be abused. But it's preferable to the available alternative."

Gun control is a policy question with assumptions about how traditional guns are distributed. We're saying "Look, as a consequence of this technology the way we do things is altered. We've stepped outside of your program. So pass your law." I was reading a piece about us in The Australian today and they kept mentioning that "this is illegal here." They mentioned it like four times. You could hear the nervousness, because it's no longer possible to just withhold things from people.

But this project does raise many interesting legal issues. Do you feel like Defense Distributed is navigating these legal waters--waters that are almost completely uncharted--in a way that respects the spirit of the law?

Of course we've been careful not to break the law. But who is to say what the spirit of the law is. Perhaps I've entered a new cynical phase after going through a couple of years of law school, but the spirit of the law is up to anyone's interpretation. So that leaves a bad taste in my mouth when we talk about the spirit of the law. It's a huge discussion that I don't even want to get into.

If there's some kind of natural law, if you will, I think we're in the spirit of that. I guess to answer your question more pointedly: no. The point isn't to match the spirit of the law. If the law was to say today that you shouldn't have a firearm, we would still say "yes you should." If you want to, of course, the idea isn't "you must have a gun," but that you're not free unless you have the choice.

I think what bothers a lot of people about this isn't necessarily gun ownership, but the access. For example, at Popular Science we've written a lot about young people--high school students and younger--who are amazingly deft with this technology. They have access to it and they get it, in many cases better than adults. So what's to stop a kid from printing a firearm? I mean, what you're doing is essentially lowering the barrier to entry for firearm possession.

The goal is to completely lower the barrier. I do see the distinction that needs to be made sometimes. People say "well, you're providing access to firearms." Okay, yes, in that the information is there, and that the technology itself assembles the component in a way that is an advantage for the non-expert. You've always been able to make a gun in this country. This just allows you to do it without knowing how--software and a machine does it for you, as opposed to other machines like a CNC mill, which no kid is going to have in his bedroom. But he might have a 3-D printer. I'll give you the entire hypothetical situation, sure. Is it much more possible now? Of course.

People say--"The mentally ill, felons, and children will all have printable guns." Well, yeah. So you must have a culture that is prepared to accept and adapt to these kind of realities. But the question to me is phrased in such a way--that is the point, to evoke an emotional response. "Now a kid can do this." This is what so many people say--"well, the mentally ill, felons, and children will all have printable guns." Well, yeah, sorry, but this is one of the negative dimensions when you lower the barriers to entry for certain things. It just is. So you must have a culture that is prepared to accept and adapt to these kind of realities, instead of pretending with these regulationist ideas that we're still stuck in. We still just pretend that things are going to keep going the way they're going--that somehow we're going to have the resources and the state power to watch everyone's 3-D printer. That's absurd. So let's accommodate.

But owning a firearm is a huge, huge responsibility. So isn't lowering the barrier to entry to that responsibility detrimental to responsible firearm ownership?

I agree with you in an abstract sense. It should be this way, sure. But how can you exact some kind of legal regime that enforces that without infringing on the rights of countless people.

To bring in a legal analogy, the First Amendment is often compared to the Second. And you know, people should say nice things to each other. But how much state power are you willing to cede and use to pretend that you can control that at the expense of vast numbers of people.

In the broader context of 3-D printing, this project has the potential to jar legislators and regulators out of their bureaucratic malaise for a moment and actually pull our regulatory framework into the 21st century--I'm not talking about firearms regulations here, but about general acknowledgment at the government level of the serious disruptions this technology is going to cause in intellectual property law and in other areas. Would you consider that a success?

If the government were to regulate this, would we consider that a success?

Perhaps it's better asked this way: Is this about creating firearms with 3-D printers, or about pushing a new technology and the mindset associated with it as far as you can push it?

I don't even have the wherewithal, ultimately, to do anything about this [bureaucratic malaise]. So we're just ignoring it. We're developing this in a way that keeps us out of a correctional institution, but honestly it's about how many free spheres of action can you expand and create. We picked the low-hanging fruit at the time. We thought it was cool as well, it was 3-D printing. And we thought: how many edges of this technology can we press--let's take it to the limit, let's see what we can do with this. And it's amazing how many people are trying to stop us.

So this is less about the Second Amendment and more about stretching this technology into a place where it's bending both its physical limits but also the limits of where the technology can go. And the limits of people's comfort zones, perhaps.

It's the second thing. It's the futurism, it's expanding free spheres of action. And if it does that it will only do so marginally. Our contribution will be here and there marginal. Vast amounts of effort and money have gone into what? Three or four custom mods, a reinforced AR plastic receiver? These are marginal. But the idea is to expand the sphere of action, because we believe in this kind of decentralized planning as an alternative to central planning.

There's so much to say about this, and it seems every other week there are new terms about gun control and all of that. I'm just sort of an enthusiast of the Second Amendment, and so yeah--I'm willing to talk about it. But we see a global thing here. I tell people sometimes "we're not making a Second Amendment argument." The basic idea is to take a technology, play futurist, and surprise people. What can you do?

But what if what you can do is something unequivocally bad? I'm sure you've thought this through extensively. What if at some point in the future an unmitigated tragedy like the one that played out in Connecticut were to occur, and the weapon used to perpetrate it turned out to be either derivative of or even directly sourced from a Defense Distributed design, would you feel any kind of responsibility or accountability? Do you worry that, regardless of how you feel, that something might come back on you legally speaking?

Oh yeah. Not in regard to personal responsibility, but to the legal question. That's one of the biggest things we're thinking about right now. How we license some of this stuff is going to be really important--this is basically the second phase for us. Once you start approaching usability, this becomes really important. There could be liability claims. Other countries might start making claims against you, saying you are in contempt of their laws. There could be all kinds of overreaction.

And I'm not saying that some of these claims might not be valid. It's inevitable. There are so many factors involved in this technology--somebody is going to do a bad build. Someone is going to hurt themselves. And as technology advances, someone will be injured, someone will be killed. We should all admit: these are possibilities and are in fact inevitabilities. But what do we want to say? Are these reasons not to be serious about the right, or about the technology? To say that it's better that some things not happen? Or that some ideas not be had?