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Messing with Mother Nature: 5 Invasion Stories

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Introduction of non-native species to a new environment is often done completely by accident. Anywhere people travel, something unseen can be traveling along, too. Planes, ships, and other methods of distant travel have taken critters to places they don't belong, and we only discover the problems they cause much later.

1. Snakes on Guam

Sometime between 1945 and 1952, the brown tree snake (Boiga irregularis) was introduced to the island of Guam, where it had never lived before. There may have been several instances of snakes stowing away on cargo ships, as Guam is a major transit point. Snakes flourished on Guam, where there was plenty of food available in the form of birds, bats, and lizards. By 1990, almost all the native birds were gone, and plans were developed to battle the snakes with multiple weapons: poison, fumigation, barriers, trapping, habitat modification, and port detection with dogs. But the snake damage continued. Since they had eaten all the birds and most of the fruit bats, pollination of native plants and trees suffered. In 2010, a new plan began: a government conservation team stuffed the carcasses of dead mice with Tylenol and airlifted them over the forests of Guam. A brown tree snake is one of the few snake species that will eat an animal it hasn't killed, and a small dose of acetaminophen is deadly to them. The "mice bombs" were attached to pieces of cardboard and paper streamers, so they would be caught in tree limbs where the snakes reside. The effectiveness of this plan has not yet been publicized, but scientists don't expect it to wipe out the snakes; they just hope to control their numbers. Photograph by Flicker user Armed Forces Pest Management Board.

2. Kudzu Bugs

The Side

Kudzu is an invasive vine that was imported from Japan in the 19th century as cattle feed, to use for erosion control, and as an ornamental plant. It is native to China, where the environment controls its spread. However, in the U.S. it flourished wildly and now covers the South. In 2009, an Asian insect called Megacopta cribraria reached the U.S., possibly by plane, and thrived by eating kudzu. You would think that a biological control of the weed would be welcomed, but there are other consequences to consider. The kudzu bug spread through several southern states, and is eating soybeans and bean crops as well as kudzu, which gave the bugs the name Bean Plataspid. They also invade homes and smell really bad, which is why they are also called Globular Stink bugs. Photograph by Flickr user Charles Lam.

3. The Catalina Island Bison

Catalina Buffalo

Santa Catalina Island is a few miles off the coast of Los Angeles. In 1924, a film crew shot a Zane Grey movie there called The Vanishing American, and brought 14 head of bison with them. The animals never showed up in the finished film, however. The story goes that the film crew left the bison behind after filming in order to save the money it would cost to transport them. By 1969, there were 400 bison on Catalina Island, and they were eating up the native plants. The Catalina Island Conservancy has employed various methods to control the size of the herd. A number of bison have been shipped out over the years: at first they were sold, then many were relocated to the Great Plains in multiple shipments. In the past few years, the Conservancy has turned to birth control methods, which appear to work and are much cheaper and less stressful than relocating the large animals. The Conservancy is also working to save the Catalina Island fox, which is a native species, and control invasive plants. Photograph by Flickr user Kenneth Hagemeyer.

4. Mussels in Michigan

A shotgun shell

Zebra mussels and Quagga mussels are both invasive species which arrived in the Great Lakes by attaching themselves to ships. Zebra mussels are native to the Caspian Sea and were first spotted near Detroit in 1988. You can follow the spread of Zebra mussels by running your mouse over the dates on this map. The Quagga mussel is native to the Dneiper River area of Ukraine, but has also invaded the Great Lakes and other areas of the U.S. Both species are upsetting the Great Lakes ecosystem:

These mussels have permanently changed the ecosystem. Before the mussels invaded, Lake Michigan water was mostly cloudy and millions of tiny microorganisms provided a food base for fish. Because the mussels filter the microorganisms, the waters today are surprisingly clear, allowing light to penetrate to greater depths, which in turn promotes prolific, nuisance algae blooms.

The mussels are also thought to be one of the main reasons that the population of the crustacean Diporeia, a major food source for fish, is declining rapidly, although industrial pollutants may also be a factor. Zebra mussel shells photographed by Flickr user Benny Mazur.

5. Farmed Algae Eaten by Shrimp

More Copepods

In order to curb global warming, there have been several projects to dump iron dust into the sea in order to encourage algae growth, because plankton absorbs carbon dioxide (CO2), a greenhouse gas. However, the location of these dumps makes a big difference. In 2009, ten tons of ferrous sulphate were pumped into the waters off Argentina. The algae bloomed, alright, but it was not the species that was expected. The project hoped to encourage growth of large diatom algae, but instead, tiny haptophytes gobbled up the iron. Haptophytes are the preferred prey of copepods, which are small shrimp-like animals. In this instance, the experiment was a failure and the iron was a loss, but scientists think that that the explosion of copepods will do no harm to the environment. They think. Copepod photograph by Flickr user Labut.

See also: Messing with Mother Nature: 5 Cautionary Tales, Messing with Mother Nature: Snakeheads, and Messing with Mother Nature: The Macquarie Island Ecosystem.

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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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iStock
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Live Smarter
Working Nights Could Keep Your Body from Healing
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iStock

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.”

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