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Thinking Hard and Long Can Cause Brain Drain : ScienceAlert

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The 19th-century American writer Wallace D. Wattles once claimed, “Thinking is the hardest and most exhausting of all labor.”

On the surface, that might sound like a contentious comparison, but a new study suggests thinking too hard and too long really can drain your brain, much like exercise can wear out the body.

Hard physical labor is obviously tiresome, but the sweat on a person’s brow or the quivering of their muscles says nothing of how hard they might be thinking.

When someone says they feel mentally exhausted, we just have to take their word for it.

As a result, scientists still don’t really understand why intense thought causes cognitive fatigue. It isn’t exactly a feeling of sleepiness; rather, it’s a sensation that tasks are getting harder to complete or focus on.

Some researchers now suspect the most abundant excitatory neurotransmitter in the brain is to blame for this lack of mental endurance.

Glutamate is an excitatory amino acid that was only properly described in the 1950s, despite the fact that it is present in over 90 percent of neuron-to-neuron communications in the human brain.

Over the decades, this underestimated chemical has continued to surprise scientists. Neurons, for instance, have been found to control the strength of their signals in the brain by regulating the amount of glutamate they release to other neurons.

Glutamate can even excite neurons to death, with as many as 8,000 glutamate molecules encapsulated in a single pouch of a synapse, the junction where two neurons meet.

The overabundance of glutamate is clearly a problem, and that’s part of why it has been linked to brain drain.

When monitoring the brain chemistry of 24 participants tasked with completing strenuous computer-based sorting tasks for over six hours, researchers found an increase in glutamate in the lateral prefrontal cortex. This is the part of the brain associated with higher-order cognitive powers, like short-term memory and decision-making.

In comparison, 16 other participants who were assigned easier tasks for the day didn’t show signs of glutamate accumulation in this part of their brain.

As such, the researchers think a rise in extracellular glutamate may be at least one of the limiting factors to human mental endurance.

Obviously, the brain gobbles up a lot of glucose when it’s working, too. Other theories suggest this energy source is probably another limiting factor, but it’s still not clear how a loss of glucose makes thinking harder, biochemically speaking.

Some researchers have proposed that a plummet in glucose triggers a loss of dopamine in the brain, which makes a person lose interest in certain cognitive tasks more easily.

“Influential theories suggested that fatigue is a sort of illusion cooked up by the brain to make us stop whatever we are doing and turn to a more gratifying activity,” explains clinical psychologist Mathias Pessiglione from the Pitié-Salpêtrière University in Paris, France.

“But our findings show that cognitive work results in a true functional alteration – accumulation of noxious substances – so fatigue would indeed be a signal that makes us stop working but for a different purpose: to preserve the integrity of brain functioning.”

Pessiglione also says there is good evidence that glutamate is eliminated from synapses during sleep.

That could be part of the reason why a night of rest can allow a person to feel mentally refreshed the next day.

A brain imaging study from 2016, which used a functional MRI (fMRI), also found the lateral prefrontal cortex (lPFC) was involved in intense cognitive effort that reduced its excitability over time.

To activate this region at the end of a long, hard day would require even more effort than at the start. Hence, the feeling of brain drain.

“Taken together with previous fMRI data, these results support a neuro-metabolic model in which glutamate accumulation triggers a regulation mechanism that makes lPFC activation more costly, explaining why cognitive control is harder to mobilize after a strenuous workday,” Pessiglione and colleagues conclude.

Glutamate is an incredibly fast-acting neurotransmitter. It’s part of what makes this amino acid so powerful. But it also makes the chemical difficult to measure.

Studies like the current one are making use of new technology to explore glutamate’s rapid role in our brains in greater detail.

The authors now hope to investigate why glutamate accumulates so much in the prefrontal cortex compared to other parts of the brain.

The study was published in Current Biology.

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Something Awesome Happens When You Use Banana Peel as an Ingredient : ScienceAlert

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Every time you peel a banana and dispose of the skin, you’re throwing away a tasty, nutritious snack.

A recent study has shown if banana peels are blanched, dried, and ground into a flour, they can be turned into baked goods that taste just as nice, if not better than wheat-based products.

Unless you’re a devoted reader of vegan cooking blogs or a Nigella Lawson fan, you’ve probably never considered cooking with a banana peel. But not only is it perfectly safe, but scientists also demonstrated it really is good for you.

When their experiments products were taste-tested, consumers reported they were just as happy with the flavors as they were with peel-free sugar cookies.

You’ll even get a generous helping of minerals and cancer-fighting nutrients. Enriched with banana peels, for instance, the sugar cookies made in the study contained much more fiber, magnesium, potassium, and antioxidant compounds.

On the downside, adding too much banana peel flour did result in cookies that were somewhat brown and hard, possibly from all the extra fiber. But when batches were made with flour containing 7.5 percent banana peel, the texture of the cookies hit a far more appealing balance.

As a bonus, the goods also kept well on the shell for three months at room temperature.

While the study only looked at the consequences of adding banana peels to baked cookies, the results suggest using banana peel flour in breads, cakes, and pasta might also be worth considering.

Last year, for instance, a study on banana peel cake found the yellow skin of the fruit provides a natural food color to the baked product as well as a nutritional boost.

A 2016 study, meanwhile, found that substituting up to 10 percent of wheat flour with banana peel flour can enrich baked bread with higher protein, carbohydrate, and fat contents.

Not into baking? Nigella Lawson has used banana peels in curry, and vegan bloggers have recently popularized the idea of banana peel bacon and pulled peel ‘pork’.

Eating the skin of this fruit isn’t just a healthy option, it can help reduce food waste. Around 40 percent of a banana’s weight is in its peel, and most of the time, this nutrition-packed skin is simply thrown away.

Sure, banana peels are pretty useless when raw. But if they are prepared right, they can actually taste pretty darn good. They can possibly even extend the shelf life of some products as the peels have antioxidant and antimicrobial properties.

The same goes for other fruit peels, too, like mango skin, which was also found to boost a cake’s antioxidant properties and improve its flavor.

So the next time you strip down a banana for the fruit inside, consider keeping the skin. Your belly might thank you later.

The study was published in ACS Food Science & Technology.

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Robot Shows It’s Possible to Swim Through The Emptiness of a Curved Universe : ScienceAlert

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If an astronaut were to suddenly become adrift in the void of interstellar space, they would be compelled to propel their body to safety, kicking and waving their limbs toward a sanctuary in the vacuum.

Sadly for them, physics isn’t so forgiving, leaving them to float without hope for eternity. If only the Universe was sufficiently curved, their flailing mightn’t be so futile.

Centuries before we left the tug of Earth, Isaac Newton succinctly explained why things moved. Whether it’s the expulsion of gas, a shove against solid ground, or the swish of a fin against a fluid, the momentum of an action is conserved by the sum of the elements involved, resulting in a reaction that drives an object forward.

Take away the air surrounding a bird’s wing or the water around a fish’s tail and the effort of each flap will push equally one way as it pulls the other, leaving the poor animal to flutter feebly without any net movement towards its destination.

Early in the 21st century, physicists considered a loophole to this rule. If a 3D space in which this movement occurs is curved, changes in an object’s shape or position won’t necessarily follow the usual rules on how momentum is exchanged, meaning it wouldn’t need a propellant.

The geometry of curved spacetime itself could mean an object’s deformation – the right kick, flap, or flutter – just might see a subtle net change in its position after all.

On one hand, the idea that the curvature of spacetime holds influence over motion is as obvious as watching a rock fall to the ground. Einstein had that one covered more than a century ago in his general theory of relativity.

But showing how the rolling hills and valleys of distorted space might affect an object’s own ability to self-propel is a whole other ballgame.

To observe this in action without traveling to the nearest space-warping black hole, a team of researchers from the Georgia Institute of Technology, Cornell University, the University of Michigan, and the University of Notre Dame constructed a model of curved space in the lab.

Their mechanical version of a spherical space consisted of a set of masses driven by actuated motors along an arching crossroads of tracks. Attached to a rotating arm, the whole setup was positioned in a way that the pull of gravity and drag of friction would be minimal.

A ‘space’ swimmer motoring on the track of a rotating boom arm. (Georgia Tech)

While the masses weren’t cut off from the physics that dominate our somewhat flatter Universe, the system was balanced so the bend in the tracks would induce the same kind of effect as a significantly curved space. Or so the team predicted.

As the robot moved, the mix of gravity, friction, and curvature combined into a movement with unique properties that were best explained by the geometry of the space.

“We let our shape-changing object move on the simplest curved space, a sphere, to systematically study the motion in curved space,” says Georgia Tech physicist Zeb Rocklin.

“We learned that the predicted effect, which was so counter-intuitive it was dismissed by some physicists, indeed occurred: as the robot changed its shape, it inched forward around the sphere in a way that could not be attributed to environmental interactions.”

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As small as the effect was, using these experimental results in line with theory could help improve the positioning of technology in localities where the Universe’s curvature becomes important. Even in gentle dips like Earth’s own gravity well, understanding how contained movements might alter ultra-precise positioning in the long term could become increasingly important.

Of course, physicists have been down the road of zero-propellant ‘impossible engines’ before. Small hypothetical forces in experiments have a way of coming and going, generating no end of debate over the validity of the theories behind them.

Further studies with more precise machinery could reveal more insights into the complex effects of swimming over the Universe’s sharp edges.

For now, we can only hope the gentle slope of the void surrounding our poor astronaut is enough to see it reach a safe haven before their oxygen runs out.

This research was published in PNAS.

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The Moon Stole Something From Deep Inside Earth Eons Ago, and Scientists Can Prove It : ScienceAlert

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Earth and its Moon are unique in the Solar System. Earth is the only planet with just one moon, and that Moon is pretty influential. In fact, without the Moon, life on Earth may not have emerged, some research suggests.

Couple that with a size ratio unlike any other planet-moon system we’ve seen – the Moon is a little over one-quarter the size of Earth – scientists, naturally, are interested in where the Moon even came from.

Many, like the potato-shaped pair of rocks that orbit Mars, are captured asteroids.

Scientists believe that the origin story of the Moon, however, is one of fire and fury: a vast spray of debris gouged out from a still-warm, barely-formed Earth on a massive collision with a Mars-sized planet named Theia, around 4.5 billion years ago. That debris, the theory goes, coalesced to form our satellite.

Now, we have new evidence of that violent birth.

Isotopes of the noble gasses helium and neon trapped in lunar meteorites recovered from Antarctica match up with those found in the solar wind, without ever having been exposed to it. This, together with a signature argon isotope concentration, suggests that those gasses were inherited from Earth, when the two bodies were one, long ago.

“Finding solar gasses, for the first time, in basaltic materials from the Moon that are unrelated to any exposure on the lunar surface was such an exciting result,” said cosmochemist Patrizia Will, formerly of ETH Zurich in Switzerland, now at Washington University in St. Louis.

Directly studying the composition of the Moon is a complicated business. We haven’t been there since 1972, and collected samples are scarce.

The Moon, however, does occasionally come to us, in the form of meteorites that are thrown in our direction when something large slams into the surface.

A bunch of these lunar meteorites, or lunaites, have been recovered; there are several hundred that we know of, found all around the world.

The subjects of the study by Will and her colleagues are just six fragments recovered from Antarctica. These fragments are all part of the same original meteoroid, and consist of a very specific kind of rock: unbrecciated – that is, not a ‘fruitcake’ of multiple rock types, as many meteorites are – basalt from a volcanic plain on the Moon.

This rock formed when magma oozed upward from the interior of the Moon and cooled quickly, covered by more layers of basalt, and thus protected from the ambient environment – including cosmic rays and the solar wind. When the basalt cooled, particles of volcanic glass formed and crystallized, and remained there, under the lunar surface.

There the rock lay, until an impact massive enough to send lunar rocks flying to Earth. Such an impact would have to have been relatively large, gouging deep into the lunar surface to reach rock that had not been exposed for eons.

To find their secrets, the research team studied the lunaites using a noble gas mass spectrometer at the ETH Zurich Noble Gas Laboratory. This instrument is one of the most powerful in the world – and the only one, the researchers said, that is capable of making their detection.

The sub-millimeter glass particles in the basalt, the team found, retained isotopic signatures of helium and neon, like tiny time capsules. And these signatures were the same as the solar wind, but were detected in much higher abundances than expected.

Because the basalt had not been exposed to the solar wind, the gasses had to have come from elsewhere.

The team found the isotope ratios of the neon were very similar to isotope ratios of neon in Earth’s mantle plumes, deep upwellings of hot molten that sample reservoirs of material deep inside Earth that are likely undisturbed since the planet formed, 4.5 billion years ago. This similarity suggests that the gasses came from Earth, the researchers concluded.

The discovery may prompt renewed interest in the study of noble gasses in meteorites, and a closer look at what else may be locked up in other lunar rocks, that was previously undetectable but now within reach, such as hydrogen and halogens.

“While such gasses are not necessary for life, it would be interesting to know how some of these noble gasses survived the brutal and violent formation of the Moon,” said geochemist Henner Busemann of ETH Zurich.

“Such knowledge might help scientists in geochemistry and geophysics to create new models that show more generally how such most volatile elements can survive planet formation, in our solar system and beyond.”

The research has been published in Science Advances.

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A Common ‘Forever Chemical’ Has Just Been Linked to Liver Cancer in Humans : ScienceAlert

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A common ‘forever chemical’ known as PFOS (perfluorooctanesulfonic acid) has been linked to liver cancer in humans in a worrying new study.

Once a key ingredient in the water-repelling product commercially known as Scotchguard, PFOS was finally phased out soon after the turn of the century following concerns over its toxicity and environmental impact.

Still, it didn’t earn its label of ‘forever chemical’ for nothing, with environmental levels of this and closely related substances remaining alarmingly high around the globe.

Now a study by researchers from the University of Southern California and the Icahn School of Medicine at Mount Sinai in the US have confirmed an association between PFOS and the development of a particularly deadly form of liver cancer.

Hepatocellular carcinoma (HCC) accounts for more than four out of five cases of liver cancer in the world. With a five-year survival rate of less than 20 percent, it’s also regarded as one of the most deadly of cancers any of us could get.

Although the total incidence of HCC has declined over the past decade in the wake of dropping hepatitis infections, a rise in non-alcoholic fatty liver disease – a condition exacerbated by obesity and high cholesterol – could confound efforts to keep cases down.

On the back of research like this new study, we might also add contaminated drinking water to that list of risk factors.

The long-chains of synthetic compounds known as perfluoroalkyl substances (PFAS) are now widely recognized as particularly nasty saboteurs of our body’s hormonal and liver systems.

In spite of a succession of bans of PFAS in jurisdictions around the globe over recent years, a regrettable amount of damage might already be seeded.

Along with substances like perfluorooctanoate (PFOA), and perfluorohexane sulfonate (PFHxS), PFAS and PFOS take their time breaking down in the environment, with half-lives of up to seven years.

That means in spite of efforts to slowly wind down their production and replace their use in anything from cosmetics to fabric protection to fire-fighting foam, today’s population continues to be exposed to whatever was being dumped into waterways decades ago. And will for some time yet.

With more than 98 percent of the adult US population having detectable concentrations of these compounds in their blood, researchers are now turning their attention to questions of what might be considered a ‘safe’ level of contamination.

Animal studies have demonstrated clear links between PFAS and liver damage. But what was really needed was a population-scale analysis of exposure and risk of ill health.

“Part of the reason there has been few human studies is because you need the right samples,” says Veronica Wendy Setiawan, a cancer epidemiologist from the Keck School of Medicine at the University of Southern California.

“When you are looking at an environmental exposure, you need samples from well before a diagnosis because it takes time for cancer to develop.”

As part of a collaboration with the University of Hawai’i called the Multiethnic Cohort Study, the researchers analyzed blood taken from 50 individuals a diagnosis of non-viral HCC.

These were compared with a carefully matched sample of bloods taken from 50 volunteers without a diagnosis.

Measuring levels of various types of PFAS in blood samples taken prior to the development of liver cancer, the researchers identified a strong association between PFOS and HCC.

Those in the top 10 percent of blood-PFOS levels, in fact, were 4.5 times more likely to develop HCC than those with lower blood-PFOS levels, providing the strongest evidence yet that we’re capable of absorbing dangerous levels of these notorious substances.

“This study fills an important gap in our understanding of the true consequences of exposure to these chemicals,” says the study’s lead author, Keck School of Medicine public health researcher Leda Chatzi.

Knowing where we can draw the line on a safe level of exposure will go a long way to refining regulations and supporting measures on monitoring environmental levels, without resorting to panic or risking the spread of misinformation.

Forever chemicals might be with us for a while to come, but the sooner we can learn just how bad they are, the better off future generations will be.

This research was published in JHEP Reports.

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Plants Appear to Be Breaking Biochemistry Rules by Making ‘Secret Decisions’

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Researchers have just discovered a previously unknown process that makes sense of the ‘secret decisions’ plants make when releasing carbon back into the atmosphere.

“We found that plants control their respiration in a way we did not expect, they control how much of the carbon from photosynthesis they keep to build biomass by using a metabolic channel,” University of Western Australia plant biochemist Harvey Millar told ScienceAlert.

 

“This happens right as the step before they decide to burn a compound called pyruvate to make and release CO2 back to the atmosphere.”

If you think back to high-school biology, you might remember that during photosynthesis, plants make sugar or sucrose. The plant typically makes an excess of sucrose; some is stored, some is degraded. This is called the citric acid (or tricarboxylic acid) cycle, and it’s equally important for life.

As part of this cycle, sucrose, which has twelve carbon atoms, is broken down into glucose with six carbons. Then glucose is broken into pyruvate, which has three carbons. Using pyruvate for energy produces carbon as a waste product, so it’s at this point where the ‘decision’ is made in the plant.

“Pyruvate is the last point for a decision,” Millar told ScienceAlert.

“You can burn it and release CO2, or you can use it to build phospholipids, stored plant oils, amino acids and other things you need to make biomass.”

The discovery came about while working on a classic plant model organism called thale cress (Arabidopsis thaliana). The researchers, led by University of Western Australia plant molecular scientist Xuyen Le, labeled pyruvate with C13 (a carbon isotope) to track where it was being shifted during the citric acid cycle, and found that pyruvate from different sources was being used differently.

 

This means the plant can actually track the source of the pyruvate and act accordingly, choosing to either release it, or hold on to it for other purposes.

“We found that a transporter on mitochondria directs pyruvate to respiration to release CO2, but pyruvate made in other ways is kept by plant cells to build biomass – if the transporter is blocked, plants then use pyruvate from other pathways for respiration,” Le said.

“Imported pyruvate was the preferred source for citrate production.”

This ability to make decisions, the team suggests, breaks the normal rules of biochemistry, where typically, every reaction is a competition and the processes don’t control where the product goes.

“Metabolic channeling breaks these rules by revealing reactions that don’t behave like this, but are set decisions in metabolic processes that are shielded from other reactions,” says Millar.

“This is not the first metabolic channel to ever be found, but they are relatively rare, and this is the first evidence of one governing this process in respiration.”

Although plants are wonderful stores of CO2 – forests alone store around 400 gigatonnes of carbon – not every molecule of CO2 that is taken up by plants is then kept. Around half of the carbon dioxide that plants take up is released back into the atmosphere.

 

Being able to get plants to store a little more carbon dioxide in this process could be a fascinating way to help our climate change woes.

“As we consider building and breeding plants for the future – we shouldn’t just be thinking about how they can be good food and food for our health, but also if they can be good carbon storers for the health of the atmosphere that we all depend on,” Millar told ScienceAlert.

Such futureproofing is yet to come, as the researchers have only just discovered this biochemical process to behind with. But if we can hijack the way plants make decisions about carbon storage, it could be one piece of the bigger climate change mitigation puzzle.

The research has been published in Nature Plants.

 

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