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The Quick 10: A Roller Derby Primer

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Here in Des Moines, we're enjoying the inaugural season of the Des Moines Derby Dames, an amateur roller derby team. It's been a lot of fun, and I have to say, it's making me wonder how well my skating skills of yesteryear have held up (probably not well. I couldn't even skate backwards at elementary school skating parties). There's something about the campy getups and unabashed violence that just makes a girl want to lace up. The sport has gone in and out of style over the years, but if you're ready to jump in on the most recent incarnation, here are a few things you'll need to know.

1. Although it has evolved over the years, roller derby has been around since the early "˜30s, the creation of Leo Seltzer. It originally started out as a roller skating marathon. Coed teams would race "across the country" on a wooden track by going 4,000 miles, watching bulbs on a map light up to show where they would be if they were actually gliding across the U.S. on eight wheels.

2. The, um, "physical" side of the sport didn't really show up until 1938, when a sports writer suggested that Seltzer introduce elbowing, whipping and slamming into the mix to keep things interesting. Seltzer wasn't crazy about the idea, but he agreed to give it a shot. Skaters and fans loved it and spectacular falls and shoves have been a beloved part of the game ever since.

3. In case you're not familiar with the sport, here are a couple of terms you need to know. "Whip" refers to a move involving two girls of the same team. Girl B comes up behind Girl A; Girl A grabs Girl B's arm and flings ("whips") her out in front. Typically, the girl being whipped out in front is the Jammer "“ the Jammer is the only skater who can score points on the team. She gets points by passing members of the opposing team, which is why it's a good thing for someone to whip her out ahead of the pack.

4. You're intrigued now, aren't you? Here are the rest of the rules.

5. You won't ever see someone wearing #1 on an official roller derby team, and the reason is quite sad. On March 24, 1937, a touring group of Roller Derbyists were in a bus when it blew a tire near Salem, Illinois. It collided with a bridge abutment, rolled over and burst into flames. According to different sources, the number of deaths totaled 19 or 20. Out of respect to those who died, the #1 has been retired from roller derby entirely. Anything else goes, though, including decimals and fractions.

6. Back in the early days of derby, famous fans included George Burns, Gracie Allen, Cary Grant, W.C. Fields and Jack Benny.

7. If you were around in the early "˜70s, you may have experienced roller derby at its peak popularity. The record attendance for a game occurred in 1972 at Comiskey Park in Chicago, with 50,118 fans showing up to watch the Chicago Midwest Pioneers play the Los Angeles Thunderbirds. That same year, Kansas City Bomber starring Raquel Welch as "the hottest thing on wheels" hit movie theaters. Sadly, things started to deteriorate the following year. One famous derby girl of the era attributes the problem to the 1973 oil crisis, which left teams unable to travel.
8. Although I think the fun names are one of the best parts of the sport, some players are bucking the trend and starting to use their own names (gasp).

9. My favorite names tend to be pop culture based (surprise, surprise) including: Lucille Brawl, Kelly KaPOWski, Hot Whips Houlihan and Assaultin' Pepa.

10. You, too, can create your own roller derby name. In fact, we have way too much fun coming up with ridiculous monikers. But if you're not good at wordplay, never fear "“ there are a couple of Roller Derby name generators out there that will do the dirty work for you. You can get a team name as well.

Do we have any derby girl _flossers? I shouldn't limit it to derby girls "“ although that's the trend these days, there are some co-ed teams and a few all-male teams. We'd love to hear about your experience in the comments. And if you're not a derby girl, feel free to fill us in on what your name would be if you were one. I just saw Eleanor Bruiseavelt and Sandra Day O'Clobber on a website and I'm pretty charmed by those.


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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.”