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How 10 Famous Landmarks Get Clean

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Happy first day of Spring! This is the time of year when we cleanse our homes of all the muck and mustiness of winter. But it's not just houses that get a thorough cleaning. Monuments and statues do, too—sometimes just once every few years, sometimes more than once a year. After looking at these photos of courageous workers going to great heights and grimy detail to shine up some much-beloved landmarks, your spring cleaning won't seem like such a chore.

1. Eiffel Tower

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The 124-year-old tower is cleaned every year, a task that requires 4 tons of wipes, 25,000 garbage bags, 10,000 doses of detergent and 105 gallons of metal cleaning solution. Every 7 years, the tower is repainted by hand with lead-free paint in three shades of brown (darkest at the bottom). The repainting requires nearly 60 tons of paint and can last up to 18 months. You can see a short newsreel video of a 1946 spring cleaning at British Pathe.

2. Richard I

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This cleaning of the Richard I statue in London, England, took place in February 1933. In an extensive 2009 restoration, conservators removed dirt and a coating of black wax from the 150-year-old statue, repainted it dark brown, and treated it with clear wax to guard against pollution and weather. 

3. The Great Westminster Clock/Big Ben

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Cleaning the face of London's famous clock is a big job: Each dial—there are four!—is 23 feet square. There are 312 panes on each face. The hour hand is 9 feet long, and the minute hand is 14 feet long. Each number is about 2 feet high. And the clock doesn't stop running while they work—so cleaners rappelling from nylon ropes have to dodge the moving hands (the minute hand moves at about a foot a minute). For this cleaning, which took place in March 1930, a cleaner named Mr. Larkin lowered himself down the face using a rope.

4. Statue of Liberty

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This cleaning of Lady Liberty's torch took place in November 1974, in preparation for the U.S.'s Bicentennial celebrations. (In high winds, the torch can sway up to 6 inches. Scary!) Until at least the 1930s, the monument got an annual wash, but not a scrub—the green patina on the statue actually keeps the copper safe. One cleaning of the interior of the statue with bicarbonate of soda, performed in 1986, leaked through to the exterior and left streaks on the statue's left cheek and right arm.

Here's video of a cleaning from the 1930s:

And check out pictures from an extensive renovation in 1984 at the Library of Congress. (Thanks to Matt for the head's up!)

Liberty Island, home of the Statue of Liberty, is currently closed due to damage from Hurricane Sandy. Thankfully, Lady Liberty's framework—which was designed by Gustav Eiffel—saved the 126-year-old statue itself from any damage, but a major cleanup on the island, estimated to cost $59 million, is underway. It was recently announced that it would reopen this summer for the Fourth of July.

5. Lincoln Memorial

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Twice a year, Honest Abe's marble doppelgänger in Washington, D.C., gets a thorough washing with a power hose.

6. Mount Rushmore

DPRBCN

This monument, completed in 1941, received its first cleaning in the summer of 2005. The 60-foot-tall granite faces of four great American presidents were blasted with highly pressurized 150-degree water, which caused all the dirt, grime, and moss that had accumulated to fall away.

7. The Structures and Statues of Acropolis Hill

Optics.Org

In 2008, scientists began using lasers to clean the surfaces of the 2500 year old monuments on Acropolis Hill in Athens, Greece, of a black film caused by pollution. The decision to use the high-tech lasers—a beam of infrared and a beam of ultraviolet rays, firing simultaneously—came after a test of 40 different methods, including mechanical and chemical processes, to determine what would clean the best while maintaining detail. Because of the rays from the lasers, goggles-wearing restorers could work for only two hours a day. You can see how the technology works in the video below:

8. The Space Needle

KomoNews

In 2008, the Space Needle got its first cleaning since it opened for the 1962 World's Fair. Working only at night, Karcher GmbH & Co.—which also cleaned Mount Rushmore—used water pressurized to 2,610.6 psi and heated to 194 degrees Fahrenheit to rid the 604-foot-tall tower of dirt, grime, and bird droppings. The cleaners lowered themselves by rope from the top of tower. You can see more of the amazing photos from the cleaning at KomoNews.

9. The Empire State Building

Master Cleaners

Window washers working at the 102-story Empire State Building couldn't attach ropes to the roof and lower themselves down because the roof wasn't flat. Instead, they hooked harnesses to eyebolts embedded inside the building. Check out this 1938 video of some daring cleaners hard at work:

10. The Hollywood Walk of Fame

John W. Adkisson / Los Angeles Times / July 21, 2010

In 2010, the LA Times profiled Walk of Fame cleaner John Peterson, who, at that point, had kept the then-2412 stars clean for 14 years. Peterson, an employee of CleanStreet, used Brasso metal polish, Windex, and paper towels to get the job done; 13 other CleanStreet employees powerwash the Walk of Fame at night to avoid tourists. The one-legged man—who lost his lower right leg to a congenital disease—was still at it as recently as 2012.

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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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8 Common Dog Behaviors, Decoded
May 25, 2017
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Dogs are a lot more complicated than we give them credit for. As a result, sometimes things get lost in translation. We’ve yet to invent a dog-to-English translator, but there are certain behaviors you can learn to read in order to better understand what your dog is trying to tell you. The more tuned-in you are to your dog’s emotions, the better you’ll be able to respond—whether that means giving her some space or welcoming a wet, slobbery kiss. 

1. What you’ll see: Your dog is standing with his legs and body relaxed and tail low. His ears are up, but not pointed forward. His mouth is slightly open, he’s panting lightly, and his tongue is loose. His eyes? Soft or maybe slightly squinty from getting his smile on.

What it means: “Hey there, friend!” Your pup is in a calm, relaxed state. He’s open to mingling, which means you can feel comfortable letting friends say hi.

2. What you’ll see: Your dog is standing with her body leaning forward. Her ears are erect and angled forward—or have at least perked up if they’re floppy—and her mouth is closed. Her tail might be sticking out horizontally or sticking straight up and wagging slightly.

What it means: “Hark! Who goes there?!” Something caught your pup’s attention and now she’s on high alert, trying to discern whether or not the person, animal, or situation is a threat. She’ll likely stay on guard until she feels safe or becomes distracted.

3. What you’ll see: Your dog is standing, leaning slightly forward. His body and legs are tense, and his hackles—those hairs along his back and neck—are raised. His tail is stiff and twitching, not swooping playfully. His mouth is open, teeth are exposed, and he may be snarling, snapping, or barking excessively.

What it means: “Don’t mess with me!” This dog is asserting his social dominance and letting others know that he might attack if they don’t defer accordingly. A dog in this stance could be either offensively aggressive or defensively aggressive. If you encounter a dog in this state, play it safe and back away slowly without making eye contact.

4. What you’ll see: As another dog approaches, your dog lies down on his back with his tail tucked in between his legs. His paws are tucked in too, his ears are flat, and he isn’t making direct eye contact with the other dog standing over him.

What it means: “I come in peace!” Your pooch is displaying signs of submission to a more dominant dog, conveying total surrender to avoid physical confrontation. Other, less obvious, signs of submission include ears that are flattened back against the head, an avoidance of eye contact, a tongue flick, and bared teeth. Yup—a dog might bare his teeth while still being submissive, but they’ll likely be clenched together, the lips opened horizontally rather than curled up to show the front canines. A submissive dog will also slink backward or inward rather than forward, which would indicate more aggressive behavior.

5. What you’ll see: Your dog is crouching with her back hunched, tail tucked, and the corner of her mouth pulled back with lips slightly curled. Her shoulders, or hackles, are raised and her ears are flattened. She’s avoiding eye contact.

What it means: “I’m scared, but will fight you if I have to.” This dog’s fight or flight instincts have been activated. It’s best to keep your distance from a dog in this emotional state because she could attack if she feels cornered.

6. What you’ll see: You’re staring at your dog, holding eye contact. Your dog looks away from you, tentatively looks back, then looks away again. After some time, he licks his chops and yawns.

What it means: “I don’t know what’s going on and it’s weirding me out.” Your dog doesn’t know what to make of the situation, but rather than nipping or barking, he’ll stick to behaviors he knows are OK, like yawning, licking his chops, or shaking as if he’s wet. You’ll want to intervene by removing whatever it is causing him discomfort—such as an overly grabby child—and giving him some space to relax.

7. What you’ll see: Your dog has her front paws bent and lowered onto the ground with her rear in the air. Her body is relaxed, loose, and wiggly, and her tail is up and wagging from side to side. She might also let out a high-pitched or impatient bark.

What it means: “What’s the hold up? Let’s play!” This classic stance, known to dog trainers and behaviorists as “the play bow,” is a sign she’s ready to let the good times roll. Get ready for a round of fetch or tug of war, or for a good long outing at the dog park.

8. What you’ll see: You’ve just gotten home from work and your dog rushes over. He can’t stop wiggling his backside, and he may even lower himself into a giant stretch, like he’s doing yoga.

What it means: “OhmygoshImsohappytoseeyou I love you so much you’re my best friend foreverandeverandever!!!!” This one’s easy: Your pup is overjoyed his BFF is back. That big stretch is something dogs don’t pull out for just anyone; they save that for the people they truly love. Show him you feel the same way with a good belly rub and a handful of his favorite treats.

The best way to say “I love you” in dog? A monthly subscription to BarkBox. Your favorite pup will get a package filled with treats, toys, and other good stuff (and in return, you’ll probably get lots of sloppy kisses). Visit BarkBox to learn more.

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