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What Makes Fireflies Glow?

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When ancient humans saw mysterious blinking lights over field and stream, they sometimes attributed the light to dragons, gods or demons. Reports in early religious writings from China and India hold the earliest recorded discovery of the true source of the lights. The glow came not from deities or monsters, but normal, mortal animals: fireflies.

Greek and Roman scholars made the first thorough examinations of fireflies (which aren’t actually flies, but a family of beetles known as Lampyridae) and other “luminous organisms.” Aristotle described almost 200 marine species with the strange power to glow.

Centuries later, the phenomena of bioluminescence (from the Greek bios (“living”) and the Latin lumen (“light”))was fairly well known, but still poorly understood. While Shakespeare mentioned the “effectual fire of the glow-worm” in Hamlet, English explorers missed their chance to land on a poorly defended Spanish Cuba, mistaking fireflies for Spanish campfires and deciding they would be outnumbered.

In 1887, French pharmacologist Raphael Dubois made a giant leap in figuring out the secrets of bioluminescence.

During one of his experiments, he took tissues from a bioluminescent clam called the common piddock and ground them up. He found that if he put the ground tissues in cold water, they glowed for a few minutes. He’d extracted the animal’s light-producing chemicals. When he put ground tissues in hot water, there was no glow, but adding the hot water to the cold water made the light come back on. He called the hot water extract luciferin (from Lucifer, Latin for “morning star”) and the cold water extract luciferase.

American biologist Edmund Newton Harvey continued on the path that Dubios had forged and spent most of his career looking for luciferin and luciferase in almost every luminous organism he could find. He discovered that luciferins and luciferases from different animals were not interchangeable; he hypothesized this was because bioluminescence and its systems had evolved to fit the various needs of different species.

You Light up My Life: The How’s and Why’s of Bioluminescence in Fireflies
The tag team of the luciferase enzyme and the luciferin molecule is the key to turning on a firefly. To make light, luciferin combines with adenosine triphosphate (ATP), a high-energy molecule that powers cells, to form luciferyl adenylate and pyrophosphate. These compounds bind to the surface of luciferase. Luciferyl adenylate then combines with oxygen to make the molecules oxyluciferin and adenosine monophosphate (AMP). Rapid energy loss from the excited oxyluciferin results in it giving off visible light.

The wavelength of this light is between 510 and 670 nanometers, making it appear like a pale yellow or orange-green color to us. In the area of the body where the light-making reaction happens—called the photic organ or the lantern—there are uric acid crystals that help reflect the light away from the abdomen.

How fireflies control their glow is still a mystery. There are several competing hypotheses that point to oxygen intake, messages from the brain, and other methods for controlling the lantern. However fireflies turn their light on and off, scientists do know what the glow is for: love and war.

For firefly larvae, bioluminescence is a defense against predators. Most firefly larvae produce chemicals within their bodies that are toxic—or at least taste terrible. Their glow warns predators that they won’t be a pleasant meal, and that trying to eat them isn’t going to do anyone any good.

Biologists think adult fireflies used to also use their glow for defense, but it eventually evolved as a tool for mate selection and communication. At certain times of night when they’re active, male fireflies will begin flashing a light pattern specific to their species. Females of the same species will watch and if a flashing male catches a female's eye, she will respond with the same pattern, on a short time delay. A flash dialogue ensues as the male locates his lady fair and flies to her to begin mating. Female fireflies are known to be fond of certain flash characteristics, like longer flash duration and bigger lanterns, and will preferentially respond to and mate with males who have more attractive glows.

Males looking to mate walk a thin line between sex and death every time they flash their light. Females of the Photuris genus of North American have figured out how to turn amorous males into an easy meal. They’ve developed an ability to replicate the mating flash code used by the Photinus genus. The Photuris females will flash back their hacked code in response to males, and when the poor suckers come looking for some loving, they walk into a dinner date that won’t end well.

Not only do the femme fatales get a meal, but they also pick up an insurance policy against getting eaten themselves. Photinus fireflies have a natural defense against predators in the form of steroidal chemicals called lucibufagins, which Photuris fireflies lack. When a female Photuris cannibalizes a male Photinus, though, the toxins slip into her bloodstream. She’s now got a defense against hungry predators and can even pass the protective chemicals onto offspring.

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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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