Original image

10 Tooth-Cleaning Devices & Products of Yesteryear

Original image

Here at mental_floss, as the name suggests, we take our dental hygiene seriously. Accordingly, we felt it would be only fitting and proper to take a closer look at the products and devices folks have used throughout the centuries to fight plaque, tartar, oral fungi and other miscellaneous cavity creeps.

1. Miswak Cleaning Stick

4 out of 5 dentists recommend sugarless gum to patients who chew gum, you say? Big deal! The miswak was recommended by Mohammad himself. In existence for thousands of years and still used to this day, the miswak comes from the twigs of the Salvadora persica (a.k.a. the Arak or Peelu tree). The fibrous stems aren’t just ideal for removing detritus, either—they're also a natural source of fluoride. A 2003 study on miswak vs. toothbrush use concludes that (when users are given proper instruction), chewing sticks are "more effective than toothbrushing for reducing plaque and gingivitis."

2. Early Toothbrushes

Thanks to international trade, by the late 1700s Europeans were consuming greater quantities of sugar than ever before, and tooth decay was consequently on the upswing. The common tooth cleaning practice at the time—rubbing a rag with soot and salt on the teeth—wasn’t doing the trick, apparently. Toothbrushes existed but were considered exotic, so they weren’t widely available. In stepped businessman William Addis, who reckoned the personal brush he used might have mass appeal and rolled the dice on manufacturing them. It was a good gamble: his brushes were an instant smash. Before long it was unfashionable not to use one—and fancy, bone-handled models of the sort shown here began to appear in droves.

3. Bejewelled Toothpicks

Back in the 1800s, it wouldn’t have been unusual to see the cream of fashionable society whipping out these silver or gold plated picks after a fine supper and going full tilt at their incisors. The trend persisted through the 1950s, and it wasn't unusual to find these sterling picks monogrammed or branded with the family crest. Takeaway: don’t be fooled by those boxes of sticks that say “Fancy Toothpicks.”

4. Dental File

From the Middle Ages through the early 1800s, barbers often doubled as dental surgeons. Because—then as now—pearly whites were considered desirable, dental surgeons were often engaged not only to perform extractions, but to whiten teeth. Their technique? Filing holes between the patient’s teeth, then coating their choppers with corrosive nitric acid. And sure enough, this process whitened people’s teeth. Unfortunately it also dissolved the enamel and eventually led to decay and worse.

5. Tongue Scrapers

Tongue cleaning has been practiced since ancient times in India and Russia. And those folks knew what they were about, since decaying bacteria and fungi on the tongue are related to many common oral care and general health problems (not to mention halitosis). Ivory and silver scrapers are just a few of the models used by the hygienically scrupulous in the 1800s, but these days you can (and should) pick up a plastic one at the nearest pharmacy.

6. Early Dental Floss

Even though folks had been using strings and strands of all sorts to dig gunk from between their teeth for centuries, the official invention of floss is generally credited to New Orleans dentist Levi Spear Parmly, who introduced his silk version in 1815. 73 years later, Johnson & Johnson received the first patent for dental floss, and the time-honored tradition of dental hygienists scolding their patients for not flossing often enough was born.

7. Rubber Disk Toothbrush

Here’s a 1931 design that never caught on, despite its very scientific assertion that “the rubber itself produce[d] a polish when used with a dentrifice [i.e., toothpaste or tooth powder]”. Perhaps the problem lay in the shape, or maybe the rubber toothbrush was just too weird compared to the brushes we'd all grown accustomed to by the '30s. At any rate, this was a huge flop.

8. Long-Handled Tongue Brush

Described as having “an unusually long handle, curved to fit the mouth," this Depression-era brush allowed its user to “reach any part of the tongue which may need cleaning,” thus saving exhausted tongue-brushers from the laborious task of raising their arms a few more inches.

9. Hands-Free Motorized Toothbrush

Wowza! This motor-propelled toothbrush allowed its busy owner to multitask, taking care of his choppers by means of a “vibrating arm," and thus leaving him free to shave, trim his nails or think really hard about whether shaving while a vibrating arm is scrubbing at his teeth is really a good idea. The design appeared and disappeared in 1937.

10. Bourbon & Scotch Flavored Toothpaste

Invented in 1954 by Don Poynter—the same man who brought us crossword-puzzle toilet tissue, by the way—these novelty pastes contained real alcohol. Thanks to a nice spread in Life magazine, they became a huge (but short-lived) seller.

Original image
iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
Original image
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!

Original image
Scientists Think They Know How Whales Got So Big
May 24, 2017
Original image

It can be difficult to understand how enormous the blue whale—the largest animal to ever exist—really is. The mammal can measure up to 105 feet long, have a tongue that can weigh as much as an elephant, and have a massive, golf cart–sized heart powering a 200-ton frame. But while the blue whale might currently be the Andre the Giant of the sea, it wasn’t always so imposing.

For the majority of the 30 million years that baleen whales (the blue whale is one) have occupied the Earth, the mammals usually topped off at roughly 30 feet in length. It wasn’t until about 3 million years ago that the clade of whales experienced an evolutionary growth spurt, tripling in size. And scientists haven’t had any concrete idea why, Wired reports.

A study published in the journal Proceedings of the Royal Society B might help change that. Researchers examined fossil records and studied phylogenetic models (evolutionary relationships) among baleen whales, and found some evidence that climate change may have been the catalyst for turning the large animals into behemoths.

As the ice ages wore on and oceans were receiving nutrient-rich runoff, the whales encountered an increasing number of krill—the small, shrimp-like creatures that provided a food source—resulting from upwelling waters. The more they ate, the more they grew, and their bodies adapted over time. Their mouths grew larger and their fat stores increased, helping them to fuel longer migrations to additional food-enriched areas. Today blue whales eat up to four tons of krill every day.

If climate change set the ancestors of the blue whale on the path to its enormous size today, the study invites the question of what it might do to them in the future. Changes in ocean currents or temperature could alter the amount of available nutrients to whales, cutting off their food supply. With demand for whale oil in the 1900s having already dented their numbers, scientists are hoping that further shifts in their oceanic ecosystem won’t relegate them to history.

[h/t Wired]