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Happy Anniversary, Lincoln Memorial!

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Today marks the anniversary of the dedication of the Lincoln Memorial in 1922. It's definitely one of the most distinguishable landmarks in Washington D.C., a place that certainly isn't lacking in memorable monuments. But how much do you really know about the famous tribute? I've tracked down some interesting tidbits for you to add to your arsenal of info.

1. It took 50 years to happen

Abraham Lincoln died on April 15, 1865. Just under two years later, in March 1867, the Lincoln Monument Association was incorporated by Congress to build an appropriate memorial to our 16th president. Apparently that was the easy part. It took the next 34 years to choose a location, and when one was finally chosen in 1901, the area was all swampland. It was another 10 years before the monument was authorized by Congress, and on February 12, 1914 (Lincoln's birthday) the first stone was officially put into place. Eight years later, the dedication ceremony took place and was attended by Lincoln's son, Robert Todd. The monument was dedicated by William Howard Taft.

2. The symbolism of the columns

There are 36 columns featured on the Lincoln Memorial. It wasn't planned this way, but the columns were eventually said to represent the 25 U.S. states at the time of Lincoln's death, plus the 11 seceded states. The names of the 48 states at the time of the monument's completion were written around the top; a plaque recognizes the later additions of Alaska and Hawaii in 1959.

3. It's been the site of some interesting events


Most people probably know that Martin Luther King, Jr.'s famous "I Have a Dream" speech took place at the Lincoln Memorial to honor Lincoln for issuing the Emancipation Proclamation.
But it was also where Richard Nixon tried to appeal to Vietnam War protestors a few days after the Kent State shootings. About 30 students were holding a vigil at the monument in the wee hours of the morning. At about 4:15 a.m., Nixon showed up to have a little chat with them. Neither side could be swayed from their opinions.
Also, for President Bush's 2001 inauguration, the Rockettes danced down the steps while performing their famous leg kicks. Not sure how I feel about that one.

4. The inscriptions

Stop squinting at the pictures "“ here's what the inscription over Lincoln's head says:
You'll also find the text of two of Lincoln's most famous speeches "“ the Gettysburg address, of course, and his second inaugural address. On this one, the word "future" was accidentally carved with an "E" instead of an "F" and had to be fixed. To this day, you can see where the error happened.

5. The stats

Lincoln himself is 19 feet, nine inches tall "“ but keep in mind that he's sitting down. The stone for the building is Indiana limestone and Yule marble; Lincoln is made of 28 blocks of Georgian marble. There are 98 steps that go from Lincoln to the reflecting pool, but the number has no significance. The Memorial is on the "tails" side of the penny, and if you look really close you can see a little figure of Lincoln etched in his proper place in the monument. The Memorial is also on the five dollar bill (although I'm sure you already knew that).

6. Is Lincoln using sign language?


If you look close at Lincoln's hands, his left hand looks like an "A" in American Sign Language and his right hand looks like an "L". Although the National Park Service denies that the positioning was intended, there might be some truth to this story. Sculptor David Chester French was quite familiar with ASL "“ his son was deaf. Furthermore, Lincoln signed federal legislation giving Gallaudet University, a college for the deaf, the right to give out "official" college degrees. So it's very possible that French snuck the reference in as a way to recognize Lincoln's contributions to the deaf.

7. The Lincoln Memorial goes high-tech

If you're headed to D.C. and didn't have time to do your research beforehand, no worries "“ your cell phone will provide all of the information you need. You can dial (202) 747-3420 to hear park rangers talk about 10 different themes, including "Debunking the Myths of the Lincoln Memorial" and "The Life and Times of Lincoln the Man". Although I suppose you don't have to be at the monument to hear the rangers talk "“ you can dial in from your couch if you really want to.

8. Are Robert E. Lee and Abraham Lincoln the same man?

You know in Harry Potter and the Sorcerer's Stone where Voldemort appears on the back of the head of poor Professor Quirrell? Apparently there's been a rumor circulating for years that the same thing is true of Lincoln and Lee. Supposedly, there's an outline of Confederate Army General Robert E. Lee's face carved on the back of the Lincoln statue. This has been repeatedly refuted, but the rumor still lurks.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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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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Live Smarter
Working Nights Could Keep Your Body from Healing
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The world we know today relies on millions of people getting up at sundown to go put in a shift on the highway, at the factory, or in the hospital. But the human body was not designed for nocturnal living. Scientists writing in the journal Occupational & Environmental Medicine say working nights could even prevent our bodies from healing damaged DNA.

It’s not as though anybody’s arguing that working in the dark and sleeping during the day is good for us. Previous studies have linked night work and rotating shifts to increased risks for heart disease, diabetes, weight gain, and car accidents. In 2007, the World Health Organization declared night work “probably or possibly carcinogenic.”

So while we know that flipping our natural sleep/wake schedule on its head can be harmful, we don’t completely know why. Some scientists, including the authors of the current paper, think hormones have something to do with it. They’ve been exploring the physiological effects of shift work on the body for years.

For one previous study, they measured workers’ levels of 8-OH-dG, which is a chemical byproduct of the DNA repair process. (All day long, we bruise and ding our DNA. At night, it should fix itself.) They found that people who slept at night had higher levels of 8-OH-dG in their urine than day sleepers, which suggests that their bodies were healing more damage.

The researchers wondered if the differing 8-OH-dG levels could be somehow related to the hormone melatonin, which helps regulate our body clocks. They went back to the archived urine from the first study and identified 50 workers whose melatonin levels differed drastically between night-sleeping and day-sleeping days. They then tested those workers’ samples for 8-OH-dG.

The difference between the two sleeping periods was dramatic. During sleep on the day before working a night shift, workers produced only 20 percent as much 8-OH-dG as they did when sleeping at night.

"This likely reflects a reduced capacity to repair oxidative DNA damage due to insufficient levels of melatonin,” the authors write, “and may result in cells harbouring higher levels of DNA damage."

DNA damage is considered one of the most fundamental causes of cancer.

Lead author Parveen Bhatti says it’s possible that taking melatonin supplements could help, but it’s still too soon to tell. This was a very small study, the participants were all white, and the researchers didn't control for lifestyle-related variables like what the workers ate.

“In the meantime,” Bhatti told Mental Floss, “shift workers should remain vigilant about following current health guidelines, such as not smoking, eating a balanced diet and getting plenty of sleep and exercise.”