Posts tagged with "Science Advances"

Splashdown: What’s’ the safest way to dive into a swimming pool?

August 3, 2022

Depending on the form and technique, diving into a swimming pool can either be poetry in motion or the aquatic equivalent of a car wreck. Now, scientists at Cornell University have used biomechanics to come up with a formula for safe diving, reports Study Finds.

After measuring the impact of head-first, hand-first, and feet-first diving, study authors put together a model for measuring the impact of different shapes as they plunge into a body of water.

For a novice, untrained diver, researchers say spinal cord and neck injuries are more likely to occur during a head-first dive of more than 26 feet. Meanwhile, collarbone injuries are more likely during a hand-first dive of roughly 40 feet, and knee injuries are likely when diving feet-first from more than 49 feet away from the water.

“Water is 1,000 times denser than air, so you are moving from a very dilute medium to a very dense medium, and you’re going to experience a huge impact,” says senior study author Sunghwan Jung, professor of Biological and Environmental Engineering in the College of Agriculture and Life Sciences, in a media release.

“Humans can choose how they dive, so we wanted to look at the effect of the  position of diving. We also wanted to come up with a more universal or general theory of how objects or different shape fronts dive into water, so we looked at the diving fronts of both humans in different postures and animals and measured the forces of impact of the different shapes.”

Study authors used a series of 3D-printed models depicting a near-life-sized human head and torso, torso and head with arms outstretched, and feet while diving. They also used models of a harbor porpoise head, a Northern gannet beak, and a basilisk lizard foot to conduct this research. The models allowed the research team to analyze the impact of curved, pointy, and flat shapes, respectively, on a body of water’s surface.

While throwing each model into water, scientists measured the forces acting on them and how they distributed over time. This approach facilitated the development of a theoretical model capable of describing the increase in force on the various shapes, and how those forces increased with the height of the dive.

Next, researchers plotted the maximum height and force impact human muscles, ligaments, and bones can withstand during a dive—calculating the probability of various injuries (collarbone, spine, and knee) at different heights and in different diving positions.

“In human biomechanics, there is a huge literature on the falling injury, especially in the elderly, and the sports injury, like concussions, but I don’t know of any other work on diving injuries,” Professor Jung explains.

Study authors hope their work helps people make safer diving choices. For example, a feet-first dive is safer from a higher perch.

Additionally, this project highlights how well-adapted certain plunge-diving animals are to withstanding and minimizing the impact of a dive. For instance, northern gannets have shallower beak angles. This unique feature helps them dive into water at up to 79 feet per second. Meanwhile, dolphins have shortened, fused cervical vertebrae, which support their head as they porpoise.

“As engineers, we are very good at making the airplane fly in the air. We are good at making a submarine move in the water, but crossing the interface, as you see in the animal world, is no easy task, and is something engineers are interested in—having a drone go from water to air or air to water, for example,” Professor Jung concludes. “So maybe this study can shed light on the new engineering design in the future that would allow systems to do this. For us, we try to understand the fundamental mechanics.”

The study is published in the journal, Science Advances.

 Research contact: @StudyFinds

Moonstruck: Lunar cycle has a marked effect on sleep

January 29, 2021

Scientists have long understood that human activity is affected by light—be it sunlight, moonlight, or artificial light. So it should be no surprise that  a new international study suggests that our ability to sleep is significantly affected by the lunar cycle, even when taking into account artificial sources of light.

The study was conducted by researchers at the University of Washington-Seattle, the Universidad Nacional de Quilmes-Bernal, Argentina, and Yale University-New Haven; and was published on January 27 in Science Advances.

Using wrist monitors, the researchers tracked sleep patterns in 98 individuals living in three indigenous communities in Argentina over the course of one to two months, The Guardian reports.

One rural community had no electricity access; a second rural community had limited access to electricity, while a third community was located in an urban setting and had full access to electricity.

Participants in all three communities showed the same pattern of sleep oscillations as the moon progressed through its 29.5-day cycle, with sleep duration changing by between 20 minutes and 90-plus minutes, and bedtimes varying by 30 minutes to 80 minutes.

In each community, the peak of participants sleeping less and staying up later occurred in the three-to-five-day period leading up to full moon nights; and the opposite occurred on the nights that preceded the new moon, the authors found.

The data were somewhat unexpected, because the researchers thought there would be less sleep and more activity on the full moon nights, said the study’s author Horacio de la Iglesia, a professor of biology at the University of Washington. “But it turns out that the nights before the full moon are the ones that have most of the moonlight during the first half of the night.”

The data that showed the “lunar phase effect” on sleep appeared to be stronger the more limited access to electricity was.

In an attempt to corroborate their findings, the researchers compared their results to similarly collected data from 464 Seattle-based students studying at the University of Washington. They found the same oscillations in sleep patterns, The Guardian says.

“Together, these results strongly suggest that human sleep is synchronised with lunar phases regardless of ethnic and socio-cultural background and of the level of urbanization,” the researchers wrote in the journal Science Advances.

Research contact: @GuardianUS

Feline groovy: Catnip provides more than a pleasurable high for your kitty

January 25, 2021

The rapturous and intoxicated behavior that cats exhibit when they are gifted with catnip is a good enough reason to keep it in stock for most pet owners. But now, a joint research project conducted in Japan and the UK has found that when felines respond to catnip they aren’t just getting high; there’s a side benefit. Catnip helps protect them from mosquitoes, The Charlotte Observer reports.

It’s all thanks to a substance called nepetalactol, which can be extracted from catnip leaves and from those of a related plant, silver vine. The team learned that this is the substance that causes the crazed rolling and rubbing cats do when they sniff the herbs.

And calling the fuss a “high” isn’t a figure of speech, either. The researchers discovered the substance activates the part of cats’ nervous systems responsible for “euphoric” effects, similar to those found in and experienced by people on drugs.

It’s an event that can last anywhere between five and 15 minutes, according to the study published Wednesday in the journal Science Advances, and is typically followed by a period of unresponsiveness.

After applying a synthetic version of nepetalactol on laboratory paper strips and giving them to cats in the study—both domestic and wild—researchers documented them rubbing, licking, and rolling around, just as they do with catnip-filled toys, the Observer reports. They even tested the substance on larger felines, including a jaguar, leopard and lynx.

But the team didn’t stop there.

Scientists have always been aware of catnip’s ability to ward off thirsty insects, so the researchers placed more nepetalactol-slathered paper strips on the floor, walls and ceilings of some cat cages and unleashed a dozen or so mosquitoes.

Cats that rubbed themselves on the chemical substance were gorged on less than those that did not have the natural repellent on their fur. The same happened when cats were placed in “a more natural setting,” the researchers said.

“We found that the cats’ reaction to silver vine is a chemical defense against mosquitoes, and perhaps against viruses and parasitic insects,” project leader Dr. Masao Miyazaki, a veterinary scientist at Iwate University in Japan, said in a news release.

The research team agrees there’s more to be discovered about catnip and mosquito activity. In future studies, the team hopes to find answers by identifying the gene responsible for cats’ reactions to the plants.

Research contact: @theobserver