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Marcos André via Flickr Creative Commons // CC BY 2.0
Marcos André via Flickr Creative Commons // CC BY 2.0

Scientists Explain How Your Shoes Untie Themselves

Marcos André via Flickr Creative Commons // CC BY 2.0
Marcos André via Flickr Creative Commons // CC BY 2.0

You know you tied your shoelaces properly. You know you did. Yet halfway down the block, you feel your sneaker slipping away from your foot. How could a knot untie itself? Scientists using slow-motion cameras may have figured it out. They published their report in the journal Proceedings of the Royal Academy A.

There are two classic shoelace knots. There’s the “rabbit comes out of the hole, runs around the tree, and returns to his hole” loop-and-pull, and then there’s the crossed-loop bunny ears approach. (Rabbits have apparently cornered the market on shoelace knots.) Both knots are prone to unraveling under strain, although bunny ears are generally considered the more secure option.

Mechanical engineers at Berkeley wondered what was producing the two knots’ different success rates. Their interest, said co-author Christopher Daily-Diamond, goes well beyond untied cross-trainers. “If you can start to understand the shoelace,” he said in a statement, “then you can apply it to other things, like DNA or microstructures, that fail under dynamic forces. This is the first step toward understanding why certain knots are better than others, which no one has really done."

The first step was to catch the knots in the act of coming undone. The researchers trained a high-speed camera on a treadmill, then co-author and runner Christine Gregg put on her sneakers and got moving.

By slowing down the camera and analyzing the physics of Gregg’s footfalls, the research team was able to spot the conspirators tugging away at those poor, unsuspecting knots. The first was the violence of each footfall, as Gregg’s shoes smacked against the treadmill with seven times the force of gravity. This impact stretched and pushed the knot. And while it was weakening, the whipping motion of the bow’s loops and ends simultaneously pulled the strands apart. These two forces combined untied Gregg’s well-formed knots.

"You really need both the impulsive force at the base of the knot and you need the pulling forces of the free ends and the loops," Daily-Diamond said. "You can't seem to get knot failure without both."

The researchers noted that knot failure is not inevitable; often it takes one specific jolt to the laces to start the unraveling clock. “[Your] laces can be fine for a really long time,” Gregg said, “and it's not until you get one little bit of motion to cause loosening that starts this avalanche effect leading to knot failure.”

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What Pet Owners Need to Know About the Latest Dog Food Recall
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A major food brand has announced a voluntary recall that concerns anyone feeding commercial pet food to their dog. As CBS News reports, dog meal and snack varieties from four brands have been tainted with pentobarbital, a chemical used in euthanasia drugs.

The compromised brands, all owned by the food company J.M. Smucker, include Kibbles 'N Bits, Gravy Train, Ol' Roy, and Skippy. Smucker has narrowed down the pentobarbital contamination to a single ingredient from a single supplier used at one of their manufacturing plants.

The pentobarbital was found in very low amounts where present and is "unlikely to pose a health risk to pets," the FDA said in a statement (any level of pentobarbital found in pet food, no matter how small, is enough to get a product pulled from shelves). Though the FDA notes that the risk to pets is low, it does warn of a few symptoms to look out for, including, "drowsiness, dizziness, excitement, loss of balance, nausea, nystagmus (eyes moving back and forth in a jerky manner) and inability to stand." The agency says that pet owners who think their animal may be sick from eating the tainted food should head to the vet.

After making sure your dog is well, toss any of the recalled pet food you still have at home so it doesn't end up in a dog bowl by mistake. Here's the full list of products to look out for.

  • Gravy Train with T-Bone Flavor Chunks, 13.2-ounce can, UPC 7910052541
  • Gravy Train with Beef Strips, 13.2-ounce can, UPC 791052542
  • Gravy Train with Lamb & Rice Chunks, 13.2-ounce can, UPC 7910052543
  • Gravy Train with Chicken Chunks, 13.2-ounce can, UPC 7910034418
  • Gravy Train with Beef Chunks, 13.2-ounce can, UPC 7910034417
  • Gravy Train with Chicken Chunks, 22-ounce can, UPC 7910051645
  • Gravy Train with Beef Chunks, 22-ounce can, UPC 7910051647
  • Gravy Train Chunks in Gravy with Beef Chunks, 13.2-ounce can, UPC 7910034417
  • Kibbles ‘N Bits 12-can Variety Pack – Chef’s Choice American Grill Burger Dinner with Real Bacon & Cheese Bits in
  • Gravy, Chef’s Choice Bistro Tender Cuts with Real Turkey Bacon & Vegetables in Gravy, 12 pack of 13.2-ounce cans, UPC 7910010377, 7910010378
  • Kibbles ‘N Bits 12-Can Variety Pack – Chef’s Choice Bistro Hearty Cuts with Real Beef, Chicken & Vegetables in Gravy, Chef’s Choice Homestyle Meatballs & Pasta Dinner with Real Beef in Tomato Sauce, 12 pack of 13.2-ounce cans, UPC 7910010382, 7910048367, 7910010378
  • Kibbles ‘N Bits 12-Can Variety Pack – Chef’s Choice Homestyle Tender Slices with Real Beef, Chicken & Vegetables in Gravy, Chef’s Choice American Grill Burger Dinner with Real Bacon & Cheese Bits in Gravy, Chef’s Choice Bistro Tender Cuts with Real Beef & Vegetables in Gravy, 12 pack of 13.2-ounce cans, UPC 7910010380, 7910010377, 7910010375
  • Kibbles ‘N Bits Chef’s Choice Bistro Tender Cuts with Real Beef & Vegetables in Gravy, 13.2-ounce can, UPC 7910010375
  • Kibbles ‘N Bits Chef’s Choice Bistro Tender Cuts with Real Turkey, Bacon & Vegetables in Gravy, 13.2-ounce can, UPC 7910010378
  • Kibbles ‘N Bits Chef’s Choice Homestyle Tender Slices with Real Beef, Chicken & Vegetables in Gravy, 13.2-ounce can, UPC 7910010380
  • Ol’ Roy Strips Turkey Bacon, 13.2-ounce can, UPC 8113117570
  • Skippy Premium Chunks in Gravy Chunky Stew, 13.2-ounce can, UPC 79100502469
  • Skippy Premium Chunks in Gravy with Beef, 13.2-ounce can, UPC 7910050250
  • Skippy Premium Strips in Gravy with Beef, 13.2-ounce can, UPC 7910050245

[h/t CBS News]

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15 Heartwarming Facts About Mister Rogers
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Though Mister Rogers' Neighborhood premiered 50 years ago, Fred Rogers remains an icon of kindness for the ages. An innovator of children’s television, his salt-of-the-earth demeanor and genuinely gentle nature taught a generation of kids the value of kindness. In celebration of the groundbreaking children's series' 50th anniversary, here are 15 things you might not have known about everyone’s favorite “neighbor.”

1. HE WAS BULLIED AS A CHILD.

According to Benjamin Wagner, who directed the 2010 documentary Mister Rogers & Me—and was, in fact, Rogers’s neighbor on Nantucket—Rogers was overweight and shy as a child, and often taunted by his classmates when he walked home from school. “I used to cry to myself when I was alone,” Rogers said. “And I would cry through my fingers and make up songs on the piano.” It was this experience that led Rogers to want to look below the surface of everyone he met to what he called the “essential invisible” within them.

2. HE WAS AN ORDAINED MINISTER.

Rogers was an ordained minister and, as such, a man of tremendous faith who preached tolerance wherever he went. When Amy Melder, a six-year-old Christian viewer, sent Rogers a drawing she made for him with a letter that promised “he was going to heaven,” Rogers wrote back to his young fan:

“You told me that you have accepted Jesus as your Savior. It means a lot to me to know that. And, I appreciated the scripture verse that you sent. I am an ordained Presbyterian minister, and I want you to know that Jesus is important to me, too. I hope that God’s love and peace come through my work on Mister Rogers’ Neighborhood.”

3. HE RESPONDED TO ALL HIS FAN MAIL.

Responding to fan mail was part of Rogers’s very regimented daily routine, which began at 5 a.m. with a prayer and included time for studying, writing, making phone calls, swimming, weighing himself, and responding to every fan who had taken the time to reach out to him.

“He respected the kids who wrote [those letters],” Heather Arnet, an assistant on Mister Rogers’ Neighborhood, told the Pittsburgh Post-Gazette in 2005. “He never thought about throwing out a drawing or letter. They were sacred."

According to Arnet, the fan mail he received wasn’t just a bunch of young kids gushing to their idol. Kids would tell Rogers about a pet or family member who died, or other issues with which they were grappling. “No child ever received a form letter from Mister Rogers," Arnet said, noting that he received between 50 and 100 letters per day.

4. ANIMALS LOVED HIM AS MUCH AS PEOPLE DID.

It wasn’t just kids and their parents who loved Mister Rogers. Koko, the Stanford-educated gorilla who understands 2000 English words and can also converse in American Sign Language, was an avid Mister Rogers’ Neighborhood watcher, too. When Rogers visited her, she immediately gave him a hug—and took his shoes off.

5. HE WAS AN ACCOMPLISHED MUSICIAN.

Though Rogers began his education in the Ivy League, at Dartmouth, he transferred to Rollins College following his freshman year in order to pursue a degree in music (he graduated Magna cum laude). In addition to being a talented piano player, he was also a wonderful songwriter and wrote all the songs for Mister Rogers' Neighborhood—plus hundreds more.

6. HIS INTEREST IN TELEVISION WAS BORN OUT OF A DISDAIN FOR THE MEDIUM.

Rogers’s decision to enter into the television world wasn’t out of a passion for the medium—far from it. "When I first saw children's television, I thought it was perfectly horrible," Rogers told Pittsburgh Magazine. "And I thought there was some way of using this fabulous medium to be of nurture to those who would watch and listen."

7. KIDS WHO WATCHED MISTER ROGERS’ NEIGHBORHOOD RETAINED MORE THAN THOSE WHO WATCHED SESAME STREET.

A Yale study pitted fans of Sesame Street against Mister Rogers’ Neighborhood watchers and found that kids who watched Mister Rogers tended to remember more of the story lines, and had a much higher “tolerance of delay,” meaning they were more patient.

8. ROGERS’S MOM KNIT ALL OF HIS SWEATERS.

If watching an episode of Mister Rogers’ Neighborhood gives you sweater envy, we’ve got bad news: You’d never be able to find his sweaters in a store. All of those comfy-looking cardigans were knitted by Fred’s mom, Nancy. In an interview with the Archive of American Television, Rogers explained how his mother would knit sweaters for all of her loved ones every year as Christmas gifts. “And so until she died, those zippered sweaters I wear on the Neighborhood were all made by my mother,” he explained.

9. HE WAS COLORBLIND.

Those brightly colored sweaters were a trademark of Mister Rogers’ Neighborhood, but the colorblind host might not have always noticed. In a 2003 article, just a few days after his passing, the Pittsburgh Post-Gazette wrote that:

Among the forgotten details about Fred Rogers is that he was so colorblind he could not distinguish between tomato soup and pea soup.

He liked both, but at lunch one day 50 years ago, he asked his television partner Josie Carey to taste it for him and tell him which it was.

Why did he need her to do this, Carey asked him. Rogers liked both, so why not just dip in?

"If it's tomato soup, I'll put sugar in it," he told her.

10. HE WORE SNEAKERS AS A PRODUCTION CONSIDERATION.

According to Wagner, Rogers’s decision to change into sneakers for each episode of Mister Rogers’ Neighborhood was about production, not comfort. “His trademark sneakers were born when he found them to be quieter than his dress shoes as he moved about the set,” wrote Wagner.

11. MICHAEL KEATON GOT HIS START ON THE SHOW.

Oscar-nominated actor Michael Keaton's first job was as a stagehand on Mister Rogers' Neighborhood, manning Picture, Picture, and appearing as Purple Panda.

12. ROGERS GAVE GEORGE ROMERO HIS FIRST PAYING GIG, TOO.

It's hard to imagine a gentle, soft-spoken, children's education advocate like Rogers sitting down to enjoy a gory, violent zombie movie like Dawn of the Dead, but it actually aligns perfectly with Rogers's brand of thoughtfulness. He checked out the horror flick to show his support for then-up-and-coming filmmaker George Romero, whose first paying job was with everyone's favorite neighbor.

“Fred was the first guy who trusted me enough to hire me to actually shoot film,” Romero said. As a young man just out of college, Romero honed his filmmaking skills making a series of short segments for Mister Rogers’ Neighborhood, creating a dozen or so titles such as “How Lightbulbs Are Made” and “Mr. Rogers Gets a Tonsillectomy.” The zombie king, who passed away in 2017, considered the latter his first big production, shot in a working hospital: “I still joke that 'Mr. Rogers Gets a Tonsillectomy' is the scariest film I’ve ever made. What I really mean is that I was scared sh*tless while I was trying to pull it off.”

13. ROGERS HELPED SAVE PUBLIC TELEVISION.

In 1969, Rogers—who was relatively unknown at the time—went before the Senate to plead for a $20 million grant for public broadcasting, which had been proposed by President Johnson but was in danger of being sliced in half by Richard Nixon. His passionate plea about how television had the potential to turn kids into productive citizens worked; instead of cutting the budget, funding for public TV increased from $9 million to $22 million.

14. HE ALSO SAVED THE VCR.

Years later, Rogers also managed to convince the Supreme Court that using VCRs to record TV shows at home shouldn’t be considered a form of copyright infringement (which was the argument of some in this contentious debate). Rogers argued that recording a program like his allowed working parents to sit down with their children and watch shows as a family. Again, he was convincing.

15. ONE OF HIS SWEATERS WAS DONATED TO THE SMITHSONIAN.

In 1984, Rogers donated one of his iconic sweaters to the Smithsonian’s National Museum of American History.

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