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Rebecca Lai via Flickr Creative Commons // CC BY 2.0

Rats Use Their Whiskers to Follow the Wind

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Rebecca Lai via Flickr Creative Commons // CC BY 2.0

We humans have all kinds of ways to determine which way the wind is blowing. We could consult a weathervane, or hold out a freshly-licked finger, or watch which way the inconsiderate gusts fling our freshly-brushed hair. To the best of our knowledge, other mammals don’t use any of these techniques. Exactly how they do it has been something of a mystery—until now. Researchers say that rats (and most likely other mammals as well) sense air and wind direction through their whiskers. They published their findings in the journal Science Advances.

The act of following the wind is called anemotaxis, after the Greek Anemoi, or wind gods. Most of what we know about anemotaxis pertains to flying insects, which have elevated wind-surfing into an art form. And while land mammals may not be riding the currents, they do rely on air currents to evade predators, find mates, and locate food.

To figure out how the animals do it, researchers at Northwestern University designed a circular arena for lab rats. On one side of the circle were five fans, and in front of each fan was the entrance to a small tunnel. At the end of the tunnel was a reward. The scientists turned on the fans at random, one per round, and trained the rats to run to the tunnel directly in front of whichever fan was blowing. At first, the rats were allowed to use all of their senses to sort out the source of the wind, from the ruffling of their fur in the breeze to the sound of the fan itself.

After 10 consecutive days of testing, the rats were able to pass the test approximately 60 percent of the time. The researchers then trimmed the rats’ whiskers, leaving all their other senses intact. With no whiskers, the rats’ success rate dropped by 20 percent.

The researchers say that the fact that they were still able to find the fan sometimes suggests that they rely on multiple forms of sensory input. "The rat clearly uses more than one cue," co-author and neuroscientist Chris Bresee said in a statement. "But rats still choose to rely heavily on their whiskers, which suggests that whiskers facilitate wind-sensing even when wild rats explore naturally."

Previous studies from the same research team have shown that rats’ whiskers bend in the same direction as the wind. The harder the wind blows, the more they bend.

Although this study included only rats, the researchers note that the whiskers of cats, dogs, and other mammals are arranged quite similarly. "It would make sense for all sorts of animals to exploit this mechanical information, given that sensing wind direction is important for so many behaviors," said co-first author Yan Yu.

Know of something you think we should cover? Email us at tips@mentalfloss.com.

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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iStock
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Here's How to Change Your Name on Facebook
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iStock

Whether you want to change your legal name, adopt a new nickname, or simply reinvent your online persona, it's helpful to know the process of resetting your name on Facebook. The social media site isn't a fan of fake accounts, and as a result changing your name is a little more complicated than updating your profile picture or relationship status. Luckily, Daily Dot laid out the steps.

Start by going to the blue bar at the top of the page in desktop view and clicking the down arrow to the far right. From here, go to Settings. This should take you to the General Account Settings page. Find your name as it appears on your profile and click the Edit link to the right of it. Now, you can input your preferred first and last name, and if you’d like, your middle name.

The steps are similar in Facebook mobile. To find Settings, tap the More option in the bottom right corner. Go to Account Settings, then General, then hit your name to change it.

Whatever you type should adhere to Facebook's guidelines, which prohibit symbols, numbers, unusual capitalization, and honorifics like Mr., Ms., and Dr. Before landing on a name, make sure you’re ready to commit to it: Facebook won’t let you update it again for 60 days. If you aren’t happy with these restrictions, adding a secondary name or a name pronunciation might better suit your needs. You can do this by going to the Details About You heading under the About page of your profile.

[h/t Daily Dot]

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