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Dietribes: Lima Beans

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• Though we have come to pronounce them differently, Lima beans were indeed named for the capital of Peru where they have been growing for over 7,500 years. Through trading and cultivation, limas became popular throughout the world, spreading across central America and the United States to Europe and Africa via Spanish and Portuguese ships!
• Lima beans also have a dark secret: raw limas should never be consumed because they contain a cyanide compound that is part of the plant's defense mechanism. Cooking the beans uncovered and draining the cooking water lessens the risks.
• What are Lima beans so defensive about, anyway? When the beans are under attack from spider mites, they release chemicals to attract natural predators of the mites as well as warn nearby plants. Amazingly, if the plants are damaged by an agricultural tool or, say, a wayward cow, they emit different stress signals that are ignored by their neighbors.

• You may be surprised to learn that one of the largest centers of Lima bean cultivation was Beverly Hills, California. Before it became a renowned affluent neighborhood, Beverly Hills was better known for its limas. The same is true, incidentally, for LAX.
• Limas also happen to make beautiful art, from a wreath to the inspiration for industrial art.

• Limas are good for science projects: just ask 18 year old Lise Desquenne of Rhode Island, who was able to determine blood type using an extract of lima beans. Her process is also more economical than the blood serum technique discovered in 1900 by Nobel Prize winner Karl Landsteiner!

• The Lima bean has also found its way into pop culture merchandise, as well as local food fare merchandise like baseball hats, bird houses and even pottery in Cape May, New Jersey during their annual festival.

• If you initially turned your noses up at the idea of limas, it's probably because of the horror of recipes like this 1974 Molded Vegetable Salad with Lima Beans. But like Brussels sprouts, there are right and wrong ways to treat this food! (And when it goes right it goes oh-so-right!)
• Personally, I have always been a huge fan of what we in the South call a butter bean (and that my local Publix refers to as a "baby lima"). Large limas are known to have a creamy texture and earthy flavor (like chick peas), but butter beans (or baby limas) are smaller with a creamier and more delicate taste. Buttery, in fact! And delicious.
• How do you Flossers take your Limas? (or Butter beans?) Did you have an aversion to them in your youth but have come around? For me the butter bean is an essential part of a comfort meal. And adding extra butter certainly never hurt …

Hungry for more? Venture into the Dietribes archive.

‘Dietribes’ appears every other Wednesday. Food photos taken by Johanna Beyenbach. You might remember that name from our post about her colorful diet.

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iStock // Ekaterina Minaeva
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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Name the Author Based on the Character
May 23, 2017
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