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The Mysterious Holes in Indiana’s Sand Dunes

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Something strange is happening on one of Indiana’s sand dunes. Holes, about a foot wide and as much as 11 feet deep, are opening up in the sand on Mount Baldy at Indiana Dunes National Lakeshore, and then vanishing within a day.

The holes made themselves known in the worst way: One swallowed a six-year-old boy last summer, burying him under 11 feet of sediment for hours. He survived, but the incident prompted the National Park Service to close Mount Baldy to the public indefinitely. Almost a year later, at least two other holes have opened and closed, and 66 anomalies have been detected in the sand.

Video shows researchers using long sticks to poke at “soft spots”—depressions in the sand where holes could open up. Grains of sand disappear into the 126-foot tall dune as if being sucked into the bottom half of an hourglass. It’s enough to make one shiver, conjuring up terrifying thoughts of being buried alive. Scarier still: Researchers don’t know for sure what’s causing the holes.

"We're seeing what appears to be a new geological phenomenon," says geologist Erin Argyilan, who has been studying the holes for several months.

But there is a working theory. The dune currently sits on top of what was once a forest, and the thought is that trees buried beneath the sand for the last century are rotting and disintegrating, leaving holes where the trunks once were. "The age of the materials and the wet conditions during the spring of 2013 may have forced these materials to become unstable, collapsing and creating openings to the surface," says the park's website.

Mount Baldy is one of Indiana’s fastest-moving dunes. The wind causes it to move between 11 and 20 feet to the south each year, park ranger Bruce Rowe tells mental_floss. “We have seen evidence of trees that have been uncovered before as the dune moved on,” Rowe says. “But in the past they were always partially decayed stumps of trees. They were called ghost forests. They fell apart as they were exposed to the air. But the idea of holes rather than stumps is completely new to science.”

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It’s also baffling because, until now, dunes were considered solid structures. “We contacted various coastal dune specialists, and one of them said, ‘If I hadn’t heard this had actually happened from you, I’d say it was impossible,’” Rowe says.

So what’s to be done? This summer, a team of researchers will use ground-penetrating radar to map the dune’s thickness and identify potential openings at its base, and take core samples to identify materials within the dune. Dr. G. William Monaghan, a geologist and geoarchaeologist with the Indiana University Glenn A. Black Laboratory of Archaeology, says they also hope to use an unmanned aerial vehicle (a.k.a. a drone) equipped with lasers that can accurately map the area’s topography and identify changes. “...Or we’ll see if there’s a void down there,” Monaghan adds. “In a way we’re not sure what we’re gonna see until we’re out there seeing it.”

Until researchers get to the bottom of the mystery, Mount Baldy will remain closed. “This has become a really fascinating science mystery that’s playing out in our park,” Rowe says.

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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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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Nick Briggs/Comic Relief
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What Happened to Jamie and Aurelia From Love Actually?
May 26, 2017
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Nick Briggs/Comic Relief

Fans of the romantic-comedy Love Actually recently got a bonus reunion in the form of Red Nose Day Actually, a short charity special that gave audiences a peek at where their favorite characters ended up almost 15 years later.

One of the most improbable pairings from the original film was between Jamie (Colin Firth) and Aurelia (Lúcia Moniz), who fell in love despite almost no shared vocabulary. Jamie is English, and Aurelia is Portuguese, and they know just enough of each other’s native tongues for Jamie to propose and Aurelia to accept.

A decade and a half on, they have both improved their knowledge of each other’s languages—if not perfectly, in Jamie’s case. But apparently, their love is much stronger than his grasp on Portuguese grammar, because they’ve got three bilingual kids and another on the way. (And still enjoy having important romantic moments in the car.)

In 2015, Love Actually script editor Emma Freud revealed via Twitter what happened between Karen and Harry (Emma Thompson and Alan Rickman, who passed away last year). Most of the other couples get happy endings in the short—even if Hugh Grant's character hasn't gotten any better at dancing.

[h/t TV Guide]

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