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Harriet Tubman's Perfect Record

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How did Harriet Tubman lead so many slaves to freedom on the Underground Railroad? With careful planning, plenty of luck, and a little opium.

“I never run my train off the track, and I never lost a passenger”—so boasted Harriet Tubman, the most successful conductor on the Underground Railroad. Tubman ran up her unblemished record while leading groups of runaways on a 650-mile odyssey from eastern Maryland to St. Catharines, Ontario. Starting in 1850, Tubman made a total of 19 journeys, personally freeing more than 300 slaves. The rewards offered for her capture totaled an astronomical $40,000 (just over $1 million in today’s money), but the bounties went unpaid.

So how exactly did she score that perfect record? Here are some tips based on her harrowing adventures—call it the Tubman Technique.

KNOW THE TERRAIN; MOVE BY NIGHT: Many slaves had never ventured far from their owners’ property. Slave owners deliberately kept them close so they wouldn’t know how to escape. As a result, runaways needed Tubman to do the navigating. She led groups along dirt roads and paths by night. If no safe house was available during the day, Tubman hid her passengers in dense forests, swamps, or other places no one would think to look. When it was safer to split up—a decision she sometimes made when she knew the group was being hunted—Tubman gave simple, easy-to-follow advice for reaching a meeting point, like “follow the drinking gourd” (the Big Dipper, which points north).

MAKE SURE EVERYONE KNOWS WHO’S IN CHARGE: With runaway slaves facing draconian punishments if they were caught, it’s no surprise that Tubman’s passengers occasionally changed their minds and wanted to return to servitude. But Tubman would have none of it—letting fugitives go back to their old homes risked exposing her entire network. When faced with timorous souls, Tubman would brandish her gun and offer them a simple choice: “You’ll be free or die a slave!”

KNOW YOUR LIMITS: Although there were thousands of slaves waiting to be freed, Tubman never bit off more than she could chew. Since large numbers would inevitably attract more attention, she usually conducted runaways in groups of 12 to 15—the most that could safely take cover in an out-of-the-way barn, cellar, or ditch.

DRUG THE KIDS: Since Tubman always tried to keep families together, her traveling parties often included small children who could slow the group down or, worse, give it away by crying at the wrong moment. To curb these problems, Tubman always carried paregoric, an opium tincture that could knock out tots for hours at a time.

WORK THE NEWS CYCLE: Slave owners often ran newspaper ads to alert bounty hunters and law enforcement about substantial rewards for capturing runaway slaves. So Tubman timed her rescues to begin on Saturdays—giving her passengers a 48-hour head start before masters could run ads in the Monday papers.

GET GOOD INTEL: During the Civil War Tubman ramped up her activities through a partnership with the Union Army, which freed slaves to weaken the Confederate economy. On June 1, 1863, Union officers provided 150 black soldiers for a Tubman-masterminded raid on rice plantations along the Combahee River in South Carolina. Tubman used an elaborate network of spies among the slave population to gather detailed intelligence about Confederate defenses, including the location of floating mines in the river. The raid freed around 750 slaves.

WHEN ALL ELSE FAILS, TRY BRIBERY: Underground Railroad conductors were no strangers to “greasing the wheels” by paying off corrupt officials and ordinary citizens. Tubman found bribes especially effective at the Canadian border, where officials could be persuaded to turn a blind eye to “visitors” who clearly weren’t tourists. The bankroll for bribes came from supporters, both white and black, called “stockholders” in railroad lingo.

DON’T BE AFRAID TO USE LIVESTOCK: Tubman’s greatest strength was her ability to think on her feet—but her use of strategic poultry didn’t hurt, either. When a route forced her to pass through her own former master’s hometown, Tubman disguised herself as an old woman and bought two chickens, carrying one under each arm to complete the disguise of a domestic slave fetching dinner. When she spotted her former master approaching in the street, Tubman “lost” the chickens and went scrambling after them, to the amusement of her master and the other white townsfolk—thus allowing her to make a quick escape.

This article originally appeared in mental_floss magazine, available wherever brilliant/lots of magazines are sold. Get a free issue here!

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iStock // Ekaterina Minaeva
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technology
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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Cs California, Wikimedia Commons // CC BY-SA 3.0
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science
How Experts Say We Should Stop a 'Zombie' Infection: Kill It With Fire
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Cs California, Wikimedia Commons // CC BY-SA 3.0

Scientists are known for being pretty cautious people. But sometimes, even the most careful of us need to burn some things to the ground. Immunologists have proposed a plan to burn large swaths of parkland in an attempt to wipe out disease, as The New York Times reports. They described the problem in the journal Microbiology and Molecular Biology Reviews.

Chronic wasting disease (CWD) is a gruesome infection that’s been destroying deer and elk herds across North America. Like bovine spongiform encephalopathy (BSE, better known as mad cow disease) and Creutzfeldt-Jakob disease, CWD is caused by damaged, contagious little proteins called prions. Although it's been half a century since CWD was first discovered, scientists are still scratching their heads about how it works, how it spreads, and if, like BSE, it could someday infect humans.

Paper co-author Mark Zabel, of the Prion Research Center at Colorado State University, says animals with CWD fade away slowly at first, losing weight and starting to act kind of spacey. But "they’re not hard to pick out at the end stage," he told The New York Times. "They have a vacant stare, they have a stumbling gait, their heads are drooping, their ears are down, you can see thick saliva dripping from their mouths. It’s like a true zombie disease."

CWD has already been spotted in 24 U.S. states. Some herds are already 50 percent infected, and that number is only growing.

Prion illnesses often travel from one infected individual to another, but CWD’s expansion was so rapid that scientists began to suspect it had more than one way of finding new animals to attack.

Sure enough, it did. As it turns out, the CWD prion doesn’t go down with its host-animal ship. Infected animals shed the prion in their urine, feces, and drool. Long after the sick deer has died, others can still contract CWD from the leaves they eat and the grass in which they stand.

As if that’s not bad enough, CWD has another trick up its sleeve: spontaneous generation. That is, it doesn’t take much damage to twist a healthy prion into a zombifying pathogen. The illness just pops up.

There are some treatments, including immersing infected tissue in an ozone bath. But that won't help when the problem is literally smeared across the landscape. "You cannot treat half of the continental United States with ozone," Zabel said.

And so, to combat this many-pronged assault on our wildlife, Zabel and his colleagues are getting aggressive. They recommend a controlled burn of infected areas of national parks in Colorado and Arkansas—a pilot study to determine if fire will be enough.

"If you eliminate the plants that have prions on the surface, that would be a huge step forward," he said. "I really don’t think it’s that crazy."

[h/t The New York Times]

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