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Mexico’s Popocatépetl volcano—a huge volcano that sits to the southeast of Mexico City—has seen a recent burst of activity. A couple weeks ago the volcano started seeping gas and ash, and yesterday the volcano blew its top in a violent explosion.

The explosion was captured on video, and in this sped up time lapse you can clearly see the shockwave of the explosion fly out from peak—shaking the clouds and racing down the volcano’s slopes. A build-up of pressure from gases seeping out of the volcano’s magma is behind these kinds of explosions. “This is akin to popping the top off a shaken bottle of soda — the dissolved bubbles come out of solution rapidly as the pressure is released and you get an explosion of soda,” says volcanologist Erik Klemmeti. On his his blog, Klemetti describes what we’re seeing:

[T]hese explosions come with a lot of force, and you can see after the initial explosion is how the clouds of water vapor around Popocatepetl shudder as the explosion front moves past. Then quickly, the upper flanks of the volcano turn grey from the rapid raining out of ash and volcanic debris (tephra).

For now, a live stream from the volcano shows that it seems to have died down. Mexico’s National Center for Prevention of Disasters still has Popocatépetl rated at Yellow, Phase 2, meaning that people should avoid the area – the same rating it has had for the past few years.

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A Chinese farm worker sprays pesticides. Photo: IFPRI-Images

“All things are poison, and nothing is without poison: the dose alone makes a thing not poison.” The wisdom of Paracelsus, a 16th-century physician and alchemist, has formed the backbone of modern toxicology. There is a safe dose of radiation, and you can be poisoned by water. Some substances, like medicine, can be incredibly helpful at low levels but deadly at high ones. A modern toxicologist’s job is to find this line, and it’s a government’s job to put limits on exposure levels to keep everything safe.

For some compounds, however, the balance between safe and deadly may not be possible. The European Union seems to believe this is the case for one set of pesticides, the so-called neonicotinoids. The EU has recently banned their use. Writing for Nature, Sharon Oosthoek says that when it comes to certain pesticides, including these now-banned neonicotinoids, we may have missed the mark—at least in Europe and Australia.

Citing two recent studies, Oosthoek says that even when pesticides like neonicotinoids are used at a level that is deemed “safe,” there may still be deadly effects on local wildlife. Looking at streams in Germany, France and Australia, scientists found that “there were up to 42% fewer species in highly contaminated than in uncontaminated streams in Europe. Highly contaminated streams in Australia showed a decrease in the number of invertebrate families by up to 27% when contrasted with uncontaminated streams.” Pesticides can have outsized effects on some species, while others endure them just fine. And year-after-year applications can cause the pesticides to build up in the environment, making them deadly after a few years even if the amount sprayed each year is within guidelines. It’s not clear whether such strong losses are the case everywhere, but they were for the studied streams.

As Paracelsus taught us, there is a safe level for everything—even pesticides. The trick is finding the right balance such that we can still derive their benefits without the unintended consequences.

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A coffee in hand as you pore over the news. A coffee in hand as you ride the subway to your co-working hub. A coffee to get the juices flowing while you brainstorm, sticking colorful Post-Its on the board. Ask nearly anyone in a creative profession the three things they can’t do without, and aside from a computer and smartphone, the top response is probably going to be coffee. But Maria Konnikova has some bad news for you, caffeine-loving creative professional: you’re doing it wrong.

Writing for the New Yorker, Konnikova surveyed the science of creative thinking:

Science is only beginning to unravel the full complexity behind different forms of creative accomplishment; creativity is notoriously difficult to study in a laboratory setting…

Still, we do know that much of what we associate with creativity—whether writing a sonnet or a mathematical proof—has to do with the ability to link ideas, entities, and concepts in novel ways.

Challenging problems can be cracked in different ways—through hard work and a systematic slog, or through a flash of creative insight. But if you’re waiting for your eureka moment, says Konnikova, you may want to lay off the coffee.

Caffeine “boosts energy and decreases fatigue; enhances physical, cognitive, and motor performance; and aids short-term memory, problem solving, decision making, and concentration,” says Konnikova. But to string together seemingly unconnected ideas to spur a creative insight, you need your brain to relax. Creativity, says Konnikova, “depends in part on the very thing that caffeine seeks to prevent: a wandering, unfocussed mind.”

Coffee can still play a role in your work flow, helping you to really get down to business when you know what needs to be done and all that’s left is to crack it out. But when you’re relying on that next flash of insight, trade out the double espresso for something that lets you relax and gets your mind wandering.

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Smell is chemistry, and the chemistry of old books gives your cherished tomes their scent. As a book ages, the chemical compounds used—the glue, the paper, the ink–begin to break down. And, as they do, they release volatile compounds—the source of the smell. A common smell of old books, says the International League for Antiquarian Booksellers, is a hint of vanilla: “Lignin, which is present in all wood-based paper, is closely related to vanillin. As it breaks down, the lignin grants old books that faint vanilla scent.”

A study in 2009 looked into the smell of old books, finding that the complex scent was a mix of “hundreds of so-called volatile organic compounds (VOCs) released into the air from the paper,” says the Telegraph. Here’s how Matija Strlic, the lead scientist behind that study, described the smell of an old book:

A combination of grassy notes with a tang of acids and a hint of vanilla over an underlying mustiness, this unmistakable smell is as much a part of the book as its contents.

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What’s the difference between a metalhead and a raver? Why do you pick the wub wub of dubstep over the twang of a guitar? Musical preference seems to be as unique as your fingerprints—you love one song and hate another, when to the ear of another listener they sound basically the same. Sure, there’s a heaping dose of social construction going on—you listen to music that you grew up with, the music that gets you in with your self-selected social group, the music that you think is cool. But there might be some biology behind your musical preference, too. The natural resonance of your skull—the unique frequency at which the bones in your noggin tend to vibrate—affects how you hear sound, and could help explain why you really rock out to Pantera but hate Metallica.

Deep inside your inner ear, within a little nautilus-shaped bone called the cochlea, tiny little hairs vibrate to transform sound into brain signals. Sound waves flowing around in the cochlea don’t just hit the hairs and go away, but rather they bounce around within your head—interacting with your skull bones. Nearly every object in the world prefers to vibrate at what is known as its “natural frequency,” your skull included, and these vibrations affect the sound waves that the hairs in your cochlea pick up.

The natural frequency of your head is a result of your skull’s size, density and shape, say scientists in a recent presentation at the meeting of the Acoustical Society of America, meaning that the vibrations of your skull are ever-so-slightly different than the person next to you. Measuring the natural vibrational frequency, the researchers found that people’s heads like to vibrate anywhere from 35 to 65 times per second, with women’s heads tending to vibrate faster than men’s.

The scientists then tested whether different people’s vibrating skulls affected which music they prefer. While the team says vibrational frequency of people’s heads didn’t seem to predict which music they liked, “skull resonance was found to moderately predict the musical keys that people disliked.”

The skull creates a kind of resonant chamber around the cochlea. Simple, integer-based ratios between the frequency of the skull, and the prominent frequencies used in a piece of music, will tend to make that music sound somewhat louder and richer to a listener. While there was little influence of resonance on the preferences, musical keys with more complex, non-integer mathematical ratios to the fundamental frequencies of the skull will tend to be sound somewhat thinner, resonate less, and possibly even induce minor acoustic distortions.

As a result, our research on this topic suggests that non-resonance between the skull and a musical key may induce a dislike of some music. While there is much research needed to fully explore this relationship more, skull resonance seems to have a subtle influence on musical preferences and selections particularly for the music we do not like.

h/t Inside Science

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