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What is Salmonella & how did it get in my tomatoes?

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Salmonella is a genus of enterobacteria (Kingdom: Bacteria, Phylum: Proteobacteria, Class: Gamma Proteobacteria, Order: Enterobacteriales, Family: Enterobacteriaceae, if you're a stickler for detail), named after Daniel Elmer Salmon, an American veterinary pathologist, who is credited as its discoverer (some sources say it was actually his research assistant, Theobald Smith, that did the discovering.) The Salmonella genus contains a motley crew of two species, several sub species and more than 2,000 serovars (groupings of microorganisms based on their cell surface antigens).

The bacteria cause salmonellosis, an infection that bestows upon you the joys of diarrhea, abdominal cramps, nausea, vomiting, fever and headaches. These symptoms usually appear within 8-72 hours after infection and can last 4-7 days. The source of infection is usually tainted food; after ingestion, Salmonella binds to the wall of the intestine, penetrates it and then starts to wreak havoc (a more in-depth explanation, if you don't mind some technical terms, can be found here).

So how did this stuff get into tomatoes?

tomato-Salmonella.jpgWhile the FDA hasn't been able to find the source of the contaminated tomatoes or figure out how they became tainted, we can take some educated guesses about the cause of contamination. Since the bacteria's preferred residence is the intestinal track of humans and animals, food usually gets tainted through contact with feces. The Center for Science in the Public Interest (CSPI) suggests a number of ways Salmonella could have gone from feces to tomatoes to you during the current outbreak:

"¢ Contaminated water was used to irrigate the tomato crops

"¢ Contaminated animal manure was used as fertilizer

"¢ Somewhere, someone involved in the process of picking, packing, processing and preparing the tomatoes didn't wash their hands after using the bathroom

"¢ Farm or wild animals spread the bacteria onto tomato crops either with their own feces or feces they tracked in from somewhere else (the 2006 E. coli problem with spinach was traced to a pack of wild boars that stepped in contaminated cow manure and brought it into a spinach field when they grazed there)

Once Salmonella was on the tomatoes (which isn't too much of a problem, since they get rinsed with chlorinated water after harvest), it could have gotten inside through cuts or scars on the skin or through the scar left when tomato is picked from the vine.

As for the source, that's a bigger problem. Pick a vegetable, any vegetable, from your fridge. Do you know where it was grown? Probably not unless you're buying it at a farmers' market directly from the folks who grew it. There's a fairly complex supply chain between the farm and your fridge (example diagrams here and here); the processors along that chain are only required to know who they bought from and who they sold to, and most don't know who is further up or down the chain.

If you've got a burning question that you'd like to see answered here, shoot me an email at flossymatt (at) Twitter users can also make nice with me and ask me questions there. Be sure to give me your name and location (and a link, if you want) so I can give you a little shout out.

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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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© Nintendo
Nintendo Will Release an $80 Mini SNES in September
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© Nintendo

Retro gamers rejoice: Nintendo just announced that it will be launching a revamped version of its beloved Super Nintendo Classic console, which will allow kids and grown-ups alike to play classic 16-bit games in high-definition.

The new SNES Classic Edition, a miniature version of the original console, comes with an HDMI cable to make it compatible with modern televisions. It also comes pre-loaded with a roster of 21 games, including Super Mario Kart, The Legend of Zelda: A Link to the Past, Donkey Kong Country, and Star Fox 2, an unreleased sequel to the 1993 original.

“While many people from around the world consider the Super NES to be one of the greatest video game systems ever made, many of our younger fans never had a chance to play it,” Doug Bowser, Nintendo's senior vice president of sales and marketing, said in a statement. “With the Super NES Classic Edition, new fans will be introduced to some of the best Nintendo games of all time, while longtime fans can relive some of their favorite retro classics with family and friends.”

The SNES Classic Edition will go on sale on September 29 and retail for $79.99. Nintendo reportedly only plans to manufacture the console “until the end of calendar year 2017,” which means that the competition to get your hands on one will likely be stiff, as anyone who tried to purchase an NES Classic last year will well remember.

In November 2016, Nintendo released a miniature version of its original NES system, which sold out pretty much instantly. After selling 2.3 million units, Nintendo discontinued the NES Classic in April. In a statement to Polygon, the company has pledged to “produce significantly more units of Super NES Classic Edition than we did of NES Classic Edition.”

Nintendo has not yet released information about where gamers will be able to buy the new console, but you may want to start planning to get in line soon.