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How to Free Dive

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Thinkstock

Humans have been free diving—plunging under the water with just a lungful of air—for over 2500 years, and today’s top pros can make it 700 feet deep on a single breath. If you want to explore the deep without a scuba tank, here’s what you’ll need to do.

1) Keep Up the Good Work

Technically, if you enjoy dunking your head just a few inches below the waves, you’re already a free diver. Congrats! Of course, if you want to join the world of deep-sea free diving—called competitive apnea—you’ll need more know-how.

2) Trust Your Reflexes

Your mammalian diving reflex, that is. When cold water splashes against your face, your body’s physiology changes. The reflex kicks in, making your heart rate sink and your outer blood vessels constrict. It also releases oxygen-rich red blood cells into your bloodstream. Altogether, thanks to the MDR, you can hold your breath longer underwater than you could on land.

3) Chase Away the CO2

The world’s best free divers can hold their breath over 10 minutes. That’s because they know how to deplete loads of CO2 from their bloodstream. Increased concentrations of CO2 encourage the urge to inhale. If you can deplete your bloodstream’s CO2 stock, you’ll be able to stay under longer.

4) Breathe Up

“Breathing up” is one of the best ways to do just that. Practice by timing your breaths, and exhaling for twice as long as you inhale. (If you breathe in for three seconds, breathe out for six.) With practice, this will stabilize your heart rate and remove extra CO2 from your bloodstream.

5) Get Your Land Legs First

You’ll need to build up your body’s CO2 tolerance, too. After doing the breathe up exercise for a few minutes, hold your breath and walk as far as you can. When you can walk the length of a football field, you’re ready to free dive.

6) Start Slow

Get in the water and go for it, starting with baby steps. Go 10 feet until it’s easy. Then shoot for 15 feet. When that’s a cinch, chip your way to 20.

7) Equalize Yourself

Once you’re below 10 feet, your body will need to adjust to the pressure—your ear especially. Pinch your nose and exhale until you hear a pop. But don’t worry about adjusting on your way back up: your ear will do that on its own.
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You don’t have to take a dive to be more interesting – you can always do that just by raising a cold Dos Equis.

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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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Opening Ceremony
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These $425 Jeans Can Turn Into Jorts
May 19, 2017
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Opening Ceremony

Modular clothing used to consist of something simple, like a reversible jacket. Today, it’s a $425 pair of detachable jeans.

Apparel retailer Opening Ceremony recently debuted a pair of “2 in 1 Y/Project” trousers that look fairly peculiar. The legs are held to the crotch by a pair of loops, creating a disjointed C-3PO effect. Undo the loops and you can now remove the legs entirely, leaving a pair of jean shorts in their wake. The result goes from this:

501069-OpeningCeremony2.jpg

Opening Ceremony

To this:

501069-OpeningCeremony3.jpg

Opening Ceremony

The company also offers a slightly different cut with button tabs in black for $460. If these aren’t audacious enough for you, the Y/Project line includes jumpsuits with removable legs and garter-equipped jeans.

[h/t Mashable]

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