FYFD

Month: August 2019

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    Seeing with Sound

    Sound carries rich information about the environment through which it’s traveled. And while many sighted people never take the time to notice this, using sound to build a mental picture of the surrounding world is something many blind people do constantly, either by studying how sounds produced by others change (passive echolocation) or by using their own sounds to pinpoint what’s around them (active echolocation). 

    In the latest It’s Okay to Be Smart video, you have a chance to learn some of the basics of active echolocation and how you can train your brain to recognize and process this extra environmental information. 

    Personally, I am not very good at this. I can hear edges but it turns out I’m very bad at figuring out where they are. That said, having spent time recently in a few anechoic chambers – where sound reflection is almost completely damped out – I’ve come to realize that even as a sighted person, I rely on sound a lot more than I think I do! (Video and image credit: It’s Okay to Be Smart)

  • Blowing Smoke

    Blowing Smoke

    It’s unusual – but not entirely unheard of – to see volcanoes blowing smoke rings during inactive periods. But given their unpredictability, scientists had not studied this phenomenon in much depth. In a recent presentation, though, a group unveiled results from numerical studies of volcanic vortex rings. They found that the decreasing pressure on rising magma allows dissolved gases to emerge as bubbles. If the magma has the right viscosity, those bubbles can merge into one big pocket that depressurizes explosively in the vent. As the hot gases burst upward, the walls of the vent cause them to curl up into a vortex ring, provided the vent is fairly circular and uniform. That sends the roiling vortex up into the atmosphere, where it cools, condenses, and becomes visible.

    The need for a circular vent matches observations of volcanic vortex rings in nature, like the infrared image shown above. Volcano watchers find that vortex rings only form from some vents, and the more circular the vent, the more likely it can produce vortex rings. (Image credit: B. Simons; research credit: F. Pulvirenti et al.; via Nat Geo; submitted by Kam-Yung Soh)

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    How Ant Stingers Work

    Anyone who’s felt the sting of a fire ant knows it only takes an instant for this species to deliver a painful blow. Scientists are uncovering why that is using some of the first-ever high-speed footage of ant stingers in action. Stingers are actually made up of multiple separate pieces, including a central stylet and a pair of lancets that move up and down along the stylet. This lancet motion pulls the stinger deeper and helps form and deliver droplets of venom. The back-and-forth motion helps ants release up to 13 venom droplets per second, a level of speed that’s key for some of its high-speed, small-scale battles. (Image and video credit: Ant Lab; research credit: A. Smith)

  • Plasma Shock Waves

    Plasma Shock Waves

    Solar flares and coronal mass ejections send out shock waves that reverberate through our solar system. But shock waves through plasma – the ionized, high-energy particles making up the solar wind – do not behave like our typical terrestrial ones. Instead of traveling through collisions between particles, these astrophysical shock waves are driven by interactions between moving, charged particles and magnetic fields. 

    A driving burst of plasma accelerated into ambient plasma creates electromagnetic forces that accelerate ambient ions to supersonic speeds, pushing the shock wave onward even without particles directly colliding. Thus far, piecing together the physics of these interactions has been a challenge because spacecraft are limited in what and where they can measure. But a group here on Earth has now recreated and observed some of this process in the lab. (Image credit: NASA Solar Dynamics Observatory; research credit: D. Schaeffer et al.; via phys.org)

  • Collecting Dew

    Collecting Dew

    In areas of the world where fresh water is scarce, one potential source is dew collection. Scientists have been working in recent years on making overnight dew collection more efficient. The challenge is that drops won’t begin to slide down an inclined surface until they are large enough for gravity to overcome the surface tension forces that pin the drop. Most efforts have focused on reducing the critical size where drops begin to slide through surface treatments and chemical coatings. 

    A recent study, however, uses a different tactic. Instead of aiming to reduce the critical drop size, these researchers built a grooved surface designed to encourage drops to grow faster. By helping the droplets coalesce quickly, their surface (right side) is able to start shedding droplets much faster than a smooth surface (left side). Under test conditions, the grooved surface was shedding droplets after only 30 minutes, whereas the smooth surface shed its first drops after 2 hours. (Image and research credit: P. Bintein et al.; see also APS Physics)

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    “In Perpetual Motion”

    “In Perpetual Motion” follows adventure photographer Krystle Wright underwater where the roiling of the ocean sometimes makes time seem to stop, transporting her to another place entirely. To me, the underside of the ocean’s surface evokes storm clouds and memories of sitting at the bottom of the pool staring up at the way light played on the surface. How about you? What do you see when the waves roll overhead? (Video and image credit: K. Wright et al.)

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    Lensing in a Straw

    While doing the sort of experiment only a kid or a scientist would pursue – namely, staring down a straw – Dianna noticed that water in a straw creates a lens-like magnification effect as the straw moves or down. This happens thanks to the curvature of the air-water-straw interface. Because water has strong surface tension, it curves dramatically as it meets the wall of the straw, and moving the straw up or down will drag some of the fluid with it, enhancing the curvature. When light refracts across that interface, it gets bent the same way it would through a lens, thereby shrinking or magnifying the objects beneath. (Video credit: D. Cowern/Physics Girl)

  • Volcanic Plume

    Volcanic Plume

    Astronauts aboard the International Space Station captured this dramatic image of Raikoke Volcano’s eruption in late June. This uninhabited Pacific Island is part of the Kuril Islands off mainland Russia. The hot plume of ash and volcanic gas rose until its density matched that of the surrounding air, at which point it could only expand horizontally. This is why the plume appears to have such a flat top. It’s similar to the cumulonimbus clouds we associate with severe thunderstorms. Scientists speculate that the white ring around the plume’s base might be water vapor condensed from ambient air pulled in to the plume’s base or a side-effect of magma flowing into the surrounding sea. (Image credit: NASA; via NASA Earth Observatory)

  • The Skipping Dambusters

    The Skipping Dambusters

    During World War II, the Allies developed “dambuster” bombs that skipped repeatedly off the surface of the water before striking their target. The goal was to cleverly bypass their enemies’ defenses both above and below the surface. Although the original dambusters used spinning spheres, the ricochet physics works for many other configurations as well; essentially, the physics are identical to rock-skipping. Conventional bullets can also skip off the water, though the required angle for skipping depends strongly on the shape of the bullet. If the geometry of the bullet impact doesn’t generate enough hydrodynamic lift, there will be no skip. (Image credit: Barnes Wallis Foundation, source; research credit: V. Murali and S. Naik, pdf; submitted by Marc A.)

  • Testing Vesicles

    Testing Vesicles

    In biology, vesicles contain a liquid surrounded by a lipid membrane. The characteristics of that membrane – like its stiffness – can change over time in ways that indicate other changes. For example, vesicles carrying HIV become stiffer as they grow more infectious. In the past, to observe these properties scientists used atomic force microscopes, which require removing the vesicles from the liquid in which they naturally reside. That’s problematic because it potentially changes how the vesicle responds. 

    Now researchers have developed a new method: a microfluidic system that subjects vesicles to electric fields in order to deform them and measures their properties without removing them from their carrier fluid. This provides a faster and more reliable method of testing a vesicle’s deformation, capable of testing hundreds of samples at a time. (Image credit: Wikimedia; research credit: A. Morshed et al.; submitted by Eric S.)