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What's the Difference? Winter Olympic Sports

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The Winter Olympics are in full swing, which can be as confusing as it is exciting. Since slalom skiing and ice dancing aren't quite as familiar as basketball and football, the nuanced differences between certain events can be a bit difficult to decipher. Let's take a look at some of the key differences between similar events.

Ice Dancing and Pairs Figure Skating


Ice dancing is obviously a form of figure skating, but there are important differences that may seem a bit subtle to those of us who are uninitiated. The easiest way to think of ice dancing is that it's ballroom dancing with skates on. Dancers have to perform to music with a definite rhythm—pair skaters can rely more on melodic tunes. Ice dancers also have to stay close to each other; they usually can't be more than two arm lengths apart.

The technical aspects of ice dancing are different, too. Ice dancers can't employ the throws and multi-revolution jumps that pair skaters use, and any spins have to be done as a couple. Ice dancers also use different lifts than pair skaters; in ice dancing, the male partner can't extend his hands above his head.

Skeleton and Luge


The two icy speed sports are very similar, but the easiest way to tell them apart is by looking at the racers' noggins. If they're going down the track head-first it's skeleton. Feet-first is luge. Lugers (or "sliders") steer by applying pressure with their shoulders or moving their sled's runners by subtly moving their legs. Skeleton sliders, on the other hand, steer by shifting their weight or dragging their feet.

Slalom and Giant Slalom and Super G

You're probably familiar with slalom skiing. Skiers go down a course marked with a number of gates that they have to maneuver between. What's the difference between all of these different flavors of slaloming, though? The regular slalom features the most tightly packed gates and is contested on the shortest course. The giant slalom takes place on a longer course with more distance between the gates.

The super G, which is short for "super giant slalom," attempts to blend the speed of downhill skiing with the strategy involved in slalom skiing. Super G courses feature the greatest distance between gates, so skiers pick up more speed than they would on a slalom or giant slalom course. Because of this quickness, super G is considered to be a "speed event" along with downhill, while slalom and giant slalom are considered "technical events."

Olympic Hockey and NHL Hockey


If you're a hardcore NHL fan, Olympic hockey might be a tiny bit disorienting. The basic game is obviously the same, but there are a few small changes in the rules that make a big difference.

In the NHL, goalies can only handle the puck behind the goal line if they're in a small area directly behind the net; in Olympic hockey, they can have the puck anywhere behind the goal line. Also, whereas NHL players have to shoot their own penalty shots unless they're injured, Olympic teams can choose anyone on their squad to take penalty shots.

On top of that, while fighting in the NHL earns a player a trip to the penalty box, in Olympic hockey it's a one-way ticket to the locker room following an ejection. The icing rule in Olympic hockey is different as well. In the NHL, a linesman only stops play due to icing once a defensive player touches the puck; in Olympic hockey, play stops as soon as the puck crosses the goal line.

At most Winter Olympics, the hockey games are contested on longer, wider rinks than the ones used for NHL games. However, to save money, the Vancouver Games are being played on an NHL-sized rink to save on construction costs.

Men's Hockey and Women's Hockey

The two variants are fairly similar, except body checking is strictly forbidden in women's hockey and will draw a penalty. Also, women's players are required to wear full facemasks while they're on the ice, which probably makes their dentists very, very happy.

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iStock // Ekaterina Minaeva
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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200 Health Experts Call for Ban on Two Antibacterial Chemicals
June 21, 2017
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In September 2016, the U.S. Food and Drug Administration (FDA) issued a ban on antibacterial soap and body wash. But a large collective of scientists and medical professionals says the agency should have done more to stop the spread of harmful chemicals into our bodies and environment, most notably the antimicrobials triclosan and triclocarban. They published their recommendations in the journal Environmental Health Perspectives.

The 2016 report from the FDA concluded that 19 of the most commonly used antimicrobial ingredients are no more effective than ordinary soap and water, and forbade their use in soap and body wash.

"Customers may think added antimicrobials are a way to reduce infections, but in most products there is no evidence that they do," Ted Schettler, science director of the Science and Environmental Health Network, said in a statement.

Studies have shown that these chemicals may actually do more harm than good. They don't keep us from getting sick, but they can contribute to the development of antibiotic-resistant bacteria, also known as superbugs. Triclosan and triclocarban can also damage our hormones and immune systems.

And while they may no longer be appearing on our bathroom sinks or shower shelves, they're still all around us. They've leached into the environment from years of use. They're also still being added to a staggering array of consumer products, as companies create "antibacterial" clothing, toys, yoga mats, paint, food storage containers, electronics, doorknobs, and countertops.

The authors of the new consensus statement say it's time for that to stop.

"We must develop better alternatives and prevent unneeded exposures to antimicrobial chemicals," Rolf Haden of the University of Arizona said in the statement. Haden researches where mass-produced chemicals wind up in the environment.

The statement notes that many manufacturers have simply replaced the banned chemicals with others. "I was happy that the FDA finally acted to remove these chemicals from soaps," said Arlene Blum, executive director of the Green Science Policy Institute. "But I was dismayed to discover at my local drugstore that most products now contain substitutes that may be worse."

Blum, Haden, Schettler, and their colleagues "urge scientists, governments, chemical and product manufacturers, purchasing organizations, retailers, and consumers" to avoid antimicrobial chemicals outside of medical settings. "Where antimicrobials are necessary," they write, we should "use safer alternatives that are not persistent and pose no risk to humans or ecosystems."

They recommend that manufacturers label any products containing antimicrobial chemicals so that consumers can avoid them, and they call for further research into the impacts of these compounds on us and our planet.