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How to Use Toilet Paper

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Certain aspects of human life are simultaneously private and universal -- everyone experiences the same stuff privately and almost no one talks about it. Pretty much everything that happens in the bathroom falls into this category, which is why I was amazed to discover that serious thought has gone into the challenges presented by toilet paper. Here are a few examples.

The Toilet Paper Algorithm

Design guru Don Norman decided to confront a common toilet paper crisis: the problem of the roll running out just when you need it most. When remodeling his home, Norman installed a dual-roll toilet paper dispenser, under the theory that there'd always be a second roll available for just such emergencies. But he quickly found that, for some reason, both rolls seemed to run out at the same time!

Norman applied some logical thinking to his problem, resulting in the article Toilet Paper Algorithms: I didn't know you had to be a computer scientist to use toilet paper. The gist of it is that Norman and his wife were subconsciously selecting whatever roll was larger at any given time, leading them both to become roughly the same size, thus running out at the same time. (Read the article for more details on the various available toilet paper algorithms...it's neat.)

For the record, Norman determined that the optimal strategy for using toilet paper in a dual-roll holder is to always use the smaller roll. This will tend to drive one roll to become empty, but will leave a full roll available.

Norman isn't alone in his analysis of toilet paper roll consumption -- Donald E. Knuth published a mathematics paper entitled The Toilet Paper Problem in The American Mathematical Monthly in 1984, including equations for analysis of toilet paper usage.

The Fold Versus Crumple Debate

I'll try to put this as delicately as I can. Apparently there's a significant debate about whether it's better to fold several sheets of paper, or crumple them together in a bunch. One major argument in favor of the "fold" method is that depending on the quality of your paper and your folding technique, you can refold (and thus reuse) a single set of sheets. The counter-argument is that this is super-gross. I have my own opinions on this issue, but let's just say I've tried multiple methodologies over the years and feel that I've perfected my technique.

So what's the distribution of crumplers versus folders in the wild? An online toilet paper usage survey has received almost 5,000 responses. At the moment, the folders are slightly in the lead (52%), but tend to be a little older than crumplers. Also, far more crumplers are male than female (70% of crumplers in the survey are male). You can take the survey or just hit the 'View' button to see the results without contributing your own.

Toilet Paper Requisition Denied

Here's some fun WWII trivia. Lieutenant Commander J. W. Coe of the submarine USS Skipjack requested 150 rolls of toilet paper from the supply officer at Mare Island Naval Base in July of 1941. The request was denied in November of 1941 with a notation saying, "Cancelled -- cannot identify." By June 1942 the situation onboard USS Skipjack was dire, and Coe sent another request, reading in part:

During the 11-3/4 months elapsing from the time of ordering the toilet paper and the present date, USS SKIPJACK personnel, despite their best efforts to await delivery of the subject material, have been unable to wait on numerous occasions, and the situation is now quite acute, particularly during depth-charge attacks by the "back stabbers."

...

SKIPJACK personnel during this period have become accustomed to the use of "crests," i.e., the vast amount of incoming non-essential paper work, and in so doing feel that the wish of the Bureau of Ships for reduction of paper work is being complied with, thus killing two birds with one stone.

Read the rest at the wonderful Snopes page detailing the event.

Got any toilet paper trivia, or an opinion on fold-versus-crumple? Share it with us in the comments!

(Toilet paper photo courtesy of Brandon Blinkenberg and Wikimedia Commons.)

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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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