Tag: science

How Much Water Pressure Can The Human Body Take?

Depending on how you look at it, the human body is either one of the most vulnerable things on the planet, or one of the most resilient.

It’s true we can do amazing things — heal where we once were bleeding, attack and destroy unfriendly microbial invaders, even knit our own bones back together.

But despite our many abilities, we’re still pretty delicate when you consider the universe around us.

There’s only a tiny window of conditions in which we can thrive, and things that are rather inconsequential in the universe — a dip in oxygen, shocking cold, a flare of nuclear radiation — would mean the end of us in the blink of an eye.

But what exactly can we take? What are the limits of our survival, and what happens to our body if we cross them?

Here we explore the body’s (many) breaking points. First up: water pressure.




What is pressure?

Pressure can generally be defined as the force, per unit area, applied to the surface of something. We’re always under a certain amount of pressure, we just don’t notice.

We hear about air pressure on the weather channel, but we actually have our own pressure in air-filled spaces of our body like our lungs, stomach, and ears.

Our internal pressure is usually equal to the outside air pressure (the weight of the atmosphere pushing down on us.)

We become uncomfortable whenever we venture away from sea level; our internal pressure is no longer equal to the ambient pressure. This is why our ears hurt when we go up in a plane or when we dive too deep underwater.

Underwater Pressure

Ever wonder why we can’t just create extra-long snorkels to breathe underwater? Seems like an obvious and easy solution for breathing without an oxygen tank, but there’s a good reason this can’t work.

For every 33 feet a diver descends the weight of the water above them increases by 15 pounds per square inch.

At only a few feet below the surface, the water pressure is already too great for the muscles that expand and contract our lungs to work, making it extremely difficult for us to draw breath.

A couple feet of water pressure isn’t enough to do serious damage yet, but looking at deeper levels shows how pressure affects us a little more gradually.

At a depth of around 100 feet, the spongy tissue of the lung begins to contract, which would leave you with only a small supply of air that was inhaled at the surface.

An ancient “dive-response” is then triggered in our body, which constricts the limbs and pushes blood toward the needier heart and brain.

If you somehow got stuck in the middle of an oceanic abyss, the deepest part of the ocean, you’d have a few things to worry about.

The lack of breathable oxygen, freezing cold, and these charming creatures, to name a few, but the huge amount of water pressure pressing down on you would definitely be the immediate threat.

Since your body’s internal pressure is so much less than the ambient pressure, your lungs would not have the strength to push back against the water pressure.

At a deep enough level, the lungs would collapse completely, killing you instantly.

This is the most extreme consequence of underwater pressure, but thankfully most of us will never have to deal with ocean depths of this magnitude.

So, how deep can we go? Scientists haven’t yet determined a hard limit for how deep we can survive underwater.

There have been a few instances of divers surviving ridiculous depths (not without side effects), but most professional free divers don’t go past 400 feet deep.

The only way to test a limit would be to test on a real, live human, so obviously there are no handy studies to help us formulate an answer.

Scientists do know, however, what would happen to a diver who crossed their body’s limit. A diver could die from bleeding into the lungs, or pass out from the strain the redistribution of blood lays on the heart.

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NASA Releases Astounding Video Of The Lagoon Nebula To Celebrate Hubble’s Birthday

The Lagoon Nebula as seen by Hubble in 1996.

Ever wanted to zoom near that central bulge in the Milky Way in the Sagittarius constellation where stars are born? NASA has almost made it possible thanks to the Earth-orbiting Hubble Space Telescope.

As a kind of a 28th Hubble birthday gift for all of us, the space agency has posted astounding videos and photos of what’s known as the Lagoon Nebula.

The main video takes viewers from far away into the very heart of the massive, colorful nebula, what NASA calls a “raucous star nursery full of birth and destruction,” 4,000 light-years away from Earth.




At the Lagoon Nebula’s heart is a massive “young” star (the million-year-old Hershel 36), 200,000 times brighter and eight times hotter than Earth’s sun.

It roils the region with ultraviolet radiation and winds carving out an exploding, undulating “fantasy landscape of ridges, cavities, and mountains of gas and dust,” gushes NASA.

Hubble was launched April 24, 1990, aboard the space shuttle Discovery and was a joint project of NASA and the European Space Agency.

The lagoon nebula seen in visible light ( left) and infrared (right).

Once a year the telescope takes a break from its assigned observations to take a detailed image of a particular spot of the cosmos.

The Hubble “has offered a new view of the universe and has reached and surpassed all expectations for a remarkable 28 years,” said NASA and the ESA. The telescope has “revolutionized almost every area of observational astronomy.”

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Prehistoric Humans May Have Practiced Brain Surgery On Cows

Marks on the cow skull (a, b, c) as compared to a human skull that underwent trepanation (d, e)

Humans have been performing brain surgery—or at least drilling holes in one others’ skulls—for thousands of years. But how did they get their practice?

A new study analyzing an exquisitely bored hole in the skull of a 5000-year-old cow (above) suggests they may have honed their skills on animals.

The bovine cranium in question was found in Vendée, France, a Neolithic site that was a trade hub for salt and cattle between 3400 and 3000 B.C.E.




Scientists originally thought the cranial hole came from a traumatic blow by another cow, but others suspected a human hand at work.

To find out if early human surgeons were responsible, scientists compared the hole in the cow’s skull to holes in two human skulls from France dated to the same period.

It was clear from the long straight lacerations that the human skulls had undergone some sort of primitive brain surgery.

Using a combination of powerful microscopes, hand lenses, and 3D reconstructions, the researchers looked for tell-tale signs of deliberate cutting on the cow skull.

Long, parallel marks surrounding the hole and traces of scraping motions matched those found around the openings in the human skulls, leading researchers to conclude that the cow’s gape came courtesy of human surgeons, they reveal today in Scientific Reports.

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Scientists Accidentally Produce An Enzyme That Devours Plastic

There are research teams around the world dedicated to finding a remedy for the growing plastic pollution crisis, but now it seems that one group of scientists have found a feasible answer — and they stumbled upon it by accident.

Researchers studying a newly-discovered bacterium found that with a few tweaks, the bug can be turned into a mutant enzyme that starts eating plastic in a matter of days, compared to the centuries it takes for plastic to break down in the ocean.

The surprise discovery was made when scientists began investigating the structure of a bacterium found in a waste dump in Japan.




The bug produced an enzyme, which the team studied using the Diamond Light Source, an intense beam of X-rays 10 billion times brighter than the sun.

At first, the enzyme looked similar to one evolved by many kinds of bacteria to break down cutin, a natural polymer used by plants as a protective layer.

But after some gentle manipulation, the team actually improved its ability to eat PET (polyethylene terephthalate), the type of plastic used in drinks bottles.

Existing examples of industrial enzymes, such as those used in detergents and biofuels, have been manipulated to work up to 1,000 times faster in just a few years.

McGeehan believes the same could be possible with the new enzyme: “It gives us scope to use all the technology used in other enzyme development for years and years and make a super-fast enzyme.

According to the team, potential future uses for the enzyme could include spraying it on the huge islands of floating plastic in oceans to break down the material.

Plastic pollution has seen renewed focus in recent times, thanks largely to attention drawn by David Attenborough’s Blue Planet II series, and through a number of legislative proposals.

Science has examined a huge range of solutions, from plastic-plucking robots to infrared identification from space, but the discovery of this mutant enzyme could herald an entirely new way of dealing with the issue.

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‘Diamonds From The Sky’ Approach Turns CO2 Into Valuable Products

Finding a technology to shift carbon dioxide (CO2), the most abundant anthropogenic greenhouse gas, from a climate change problem to a valuable commodity has long been a dream of many scientists and government officials.

Now, a team of chemists says they have developed a technology to economically convert atmospheric COdirectly into highly valued carbon nanofibers for industrial and consumer products.

The team will present brand-new research on this new CO2 capture and utilization technology at the 250th National Meeting & Exposition of the American Chemical Society (ACS). ACS is the world’s largest scientific society.

The national meeting, which takes place here through Thursday, features more than 9,000 presentations on a wide range of science topics.




We have found a way to use atmospheric CO2 to produce high-yield carbon nanofibers,” says Stuart Licht, Ph.D., who leads a research team at George Washington University.

“Such nanofibers are used to make strong carbon composites, such as those used in the Boeing Dreamliner, as well as in high-end sports equipment, wind turbine blades and a host of other products.”

Previously, the researchers had made fertilizer and cement without emitting CO2, which they reported.

Now, the team, which includes postdoctoral fellow Jiawen Ren, Ph.D., and graduate student Jessica Stuart, says their research could shift CO2from a global-warming problem to a feed stock for the manufacture of in-demand carbon nanofibers.

Licht calls his approach “diamonds from the sky.”

That refers to carbon being the material that diamonds are made of, and also hints at the high value of the products, such as the carbon nanofibers that can be made from atmospheric carbon and oxygen.

Because of its efficiency, this low-energy process can be run using only a few volts of electricity, sunlight and a whole lot of carbon dioxide.

At its root, the system uses electrolytic syntheses to make the nanofibers.

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Fruit Bat’s Echolocation May Work Like Sophisticated Surveillance Sonar

The new open-access paper in PLoS Biology shows how the animals are able to navigate using a different system from other bats.

Before people thought that this bat was not really good at echolocation, and just made these simple clicks,” said lead author Wu-Jung Lee, a researcher at the UW’s Applied Physics Laboratory.

“But this bat species is actually very special — it may be using a similar technique that engineers have perfected for sensing remotely.”

While most other bats emit high-pitched squeals, the fruit bat simply clicks its tongue and produces signals that are more like dolphin clicks than other bats’ calls.

Fruit bats can also see quite well, and the animals switch and combine sensory modes between bright and dark environments.

An earlier study showed that Egyptian fruit bats send clicks in different directions without moving their head or mouth, and suggested that the animals can perform echolocation, the form of navigation that uses sound, better than previously suspected.




Lee and colleagues measured the animals in the “bat lab” at Johns Hopkins University by capturing high-speed video and ultrasonic audio of bats during flight to study the mechanism of their behavior and navigation.

In measuring echolocation signals from fruit bats with a three-dimensional array of microphones, Lee did not solve the mystery of the seemingly motionless tongue clicks, but she did notice something strange.

The beam of different frequencies of sound waves emitted by the bats do not align at the center and form a bullseye, as one would expect from a simple sound source, but instead the beam of sound is off-center at higher frequencies.

Lee recognized the pattern as a common one in radar and sonar surveillance systems.

Invented in the early 20th century and now used throughout civil and military applications, airplanes, ships and submarines emit pulses of radio waves in the air, or sound underwater, and then analyze the returning waves to detect objects or hazards.

While a simple single-frequency sonar has a tradeoff between the angular coverage and image sharpness, a “frequency-scanning sonar” solves this problem by pointing different frequencies of sound at slightly different angles to get fine-grained acoustic images over a large area.

Lee wondered if the fruit bats could be using the same technique when echolocating. She created a computer model of what might happen when the tongue click from the front of the mouth travels out and passes between the bat’s lips.

The elongated shape of the bat’s mouth creates varying distances between the sound source and the gaps between its teeth, and this creates positive or negative interference between sound waves of different frequencies.

The result, Lee’s model shows, is that different frequencies point in different directions — just as a frequency-scanning sonar would act.

For me, what’s exciting is the idea that you almost have a convergence between a system that was evolved, and the effects are very similar to what we have invented as humans,” Lee said.

“This is not the classic case where we learn from nature — we found out that the bat may be doing the same thing as a system we invented many years ago.”

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Chocolate Production Generates A Lot Of Pollution

For decades, commuters and tourists have delighted in the mouthwatering smells radiating from the Blommer Chocolate Co.’s factory near the Chicago River downtown.

But following a federal agency’s complaint, the aroma will soon disappear.

The U.S. Environmental Protection Agency recently cited the family-run business for alleged clean-air violations, and officials are hurrying to install equipment that will reduce emissions — and stop the smell.

It’ll start to go away as we put pollution abatement equipment in place,” the company’s vice president, Rick Blommer, told The Associated Press.




The company that makes chocolate liquor, cocoa butter and other products for bulk sale is trying to resolve allegations that its cocoa-crushing process causes air pollution.

Still, the demise of the rich, brownie smell spilling from the 66-year-old Blommer plant will be a bitter loss, said odor researcher Alan Hirsch, head of the Chicago-based Smell and Taste Treatment and Research Foundation.

Chocolate smells put people in a relaxed state,” said Hirsch, who likened the effect of chocolate vapors on the brain to an antidepressant.

It’s been shown bad odors increase aggression; pleasant ones make people more docile. So you could say the chocolate smell is a real service to Chicago.

Smells are a big deal in this city once closely associated with the stench of slaughtered cows and whose very name etymologists say comes from the American Indian words for skunk or onion.

But a pleasant smell to some is pollution to others.

In citing the company earlier this month, the EPA said inhaling the plant’s emissions in high concentrations can harm children, the elderly and people with heart and lung diseases.

But within smelling range of the factory, it’s nearly impossible to find anyone who doesn’t rave about the chocolate aroma.

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Can Fasting Help You Lose Weight And Live For Longer?

New research suggests that fasting could slow down ageing and extend people’s lives. What fasting diets are there – are are they a good idea?

Intermitent Fasting is in fashion.

There are all sorts of ratios and variants on core idea of dramatically restricting calories for a few days each week while eating normally on other days.

And while this approach seems totally at odds with the traditional health advice we’ve always been given about eating balanced, regular meals, a growing number of scientists are saying IF diets can reduce our chances of developing some chronic diseases and may even add years our lives.




The most recent evidence comes from the University of South California, where researchers found that 34 people on a low-calorie, low-protein diet had a decrease in risk factors associated with chronic diseases such as cancer, heart disease and Type 2 diabetes.

This builds on a number of earlier findings that suggest fasting reduces blood pressure, increases cellular repair and metabolic rate, and protects against conditions such as dementia and Alzheimer’s.

And while it is not be a step towards eternal life, a 2015 study at the University of Florida revealed that fasting on alternate days increased the gene related to anti-ageing in human cells.

Short periods of starvation effectively mimic the eating habits of our ancestors, who did not have access to grocery stores or food around the clock.

It’s not without its risks and downsides, though. Dieticians warn that skipping meals can cause dizziness, difficulties sleeping, dehydration and headaches.

Others are concerned it reinforces poor eating habits. “These diets can encourage a ‘scrimp and splurge’ approach to eating,” says British nutritionist Julia Harding.

“They don’t necessarily promote a good understanding of food. People need to make sure they’re eating nutritious, balanced meals on their ‘off days’ and think beyond calories.”

As fasting continues to win new fans, the array of variations is about as dizzying as a day on zero calories.

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All By Itself, The Humble Sweet Potato Colonized The World

A chromolithograph of Christopher Columbus arriving at the Caribbean.

Of all the plants that humanity has turned into crops, none is more puzzling than the sweet potato.

Indigenous people of Central and South America grew it on farms for generations, and Europeans discovered it when Christopher Columbus arrived in the Caribbean.

In the 18th century, however, Captain Cook stumbled across sweet potatoes again — over 4,000 miles away, on remote Polynesian islands. European explorers later found them elsewhere in the Pacific, from Hawaii to New Guinea.

The distribution of the plant baffled scientists. How could sweet potatoes arise from a wild ancestor and then wind up scattered across such a wide range?

Was it possible that unknown explorers carried it from South America to countless Pacific islands?

An extensive analysis of sweet potato DNA, published on Thursday in Current Biology, comes to a controversial conclusion: Humans had nothing to do with it.




The bulky sweet potato spread across the globe long before humans could have played a part — it’s a natural traveler.

Some agricultural experts are skeptical.

This paper does not settle the matter,” said Logan J. Kistler, the curator of archaeogenomics and archaeobotany at the Smithsonian Institution.

Alternative explanations remain on the table, because the new study didn’t provide enough evidence for exactly where sweet potatoes were first domesticated and when they arrived in the Pacific.

We still don’t have a smoking gun,” Dr. Kistler said.

The sweet potato, Ipomoea batatas, is one of the most valuable crops in the world, providing more nutrients per farmed acre than any other staple.  It has sustained human communities for centuries.

A sweet potato farmer in in Papua New Guinea. The plant arrived there long before humans, scientists reported.

 

Scientists have offered a number of theories to explain the wide distribution of I. batatas.

Some scholars proposed that all sweet potatoes originated in the Americas, and that after Columbus’s voyage, they were spread by Europeans to colonies such as the Philippines. Pacific Islanders acquired the crops from there.

As it turned out, though, Pacific Islanders had been growing the crop for generations by the time Europeans showed up. On one Polynesian island, archaeologists have found sweet potato remains dating back over 700 years.

A radically different hypothesis emerged: Pacific Islanders, masters of open-ocean navigation, picked up sweet potatoes by voyaging to the Americas, long before Columbus’s arrival there.

The evidence included a suggestive coincidence: In Peru, some indigenous people call the sweet potato cumara. In New Zealand, it’s kumara.

A potential link between South America and the Pacific was the inspiration for Thor Heyerdahl’s famous 1947 voyage aboard the Kon-Tiki. He built a raft, which he then successfully sailed from Peru to the Easter Islands.

Genetic evidence only complicated the picture. Examining the plant’s DNA, some researchers concluded that sweet potatoes arose only once from a wild ancestor, while other studies indicated that it happened at two different points in history.

According to the latter studies, South Americans domesticated sweet potatoes, which were then acquired by Polynesians. Central Americans domesticated a second variety that later was picked up by Europeans.

Hoping to shed light on the mystery, a team of researchers recently undertook a new study — the biggest survey of sweet potato DNA yet. And they came to a very different conclusion.

Their research pointed to only one wild plant as the ancestor of all sweet potatoes. The closest wild relative is a weedy flower called Ipomoea trifida that grows around the Caribbean.

Its pale purple flowers look a lot like those of the sweet potato.

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Have You Ever Wonder How Does A Mosquito Fly?

Mosquitoes are strange fliers. Compared with other insects, birds, and bats, their shorter wing strokes and oddly long—and skinny—wings have made scientists wonder how they can get off the ground at all.

Now, a new study shows how these animals get their lift: with help from a clever rotation of their wings.




Most animals generate lift, the force that keeps them aloft, during the downstroke of each wing beat.

This creates a vortex of swirling air over the wing’s leading edge, which lowers the pressure above the wing and pushes the animal up.


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