FYFD

Tag: biology

  • Flying Backwards

    Flying Backwards

    Spend a summer afternoon floating in a kayak and chances are you’ll see some impressive aerial acrobatics from dragonflies. One of the dragonfly’s superpowers is its ability to fly backwards, which helps it evade predators and take-off from almost any orientation. To do this, the dragonfly rotates its body so that it is nearly vertical, thereby changing the direction it generates lift. In engineering terms, this is “force-vectoring,” similar to the techniques used by helicopters and vertical-take-off jets. 

    Scientists found that backwards-flying dragonflies could generate forces two to three times their body weight, in part due to the strong leading-edge vortices (bottom image) formed on the forewings. They also found that the hind wings are timed so that their lift is enhanced by catching the trailing vortex of the first pair of wings. Engineers hope to use what they’re learning from insect flight to build more capable flying robots. (Image and research credit: A. Bode-Oke et al., source; via Science)

  • Using Embolisms to Fight Cancer

    Using Embolisms to Fight Cancer

    Blocking blood vessels by creating embolisms is, under most circumstances, very bad. But researchers are exploring ways to fight cancer by intentionally and strategically creating these blockages. In gas embolotherapy, researchers inject fluid droplets, which can carry chemotherapy drugs, into the bloodstream. Once they circulate into a cancerous tumor, they use ultrasound to vaporize the droplet and create a gas bubble. Those bubbles lodge inside the capillaries of the tumor, starving it of fresh blood and trapping the chemotherapy drugs inside. It’s a one-two punch to the cancer. Without blood flow, the cancer cells die, and, since the cancer-killing drugs get mostly trapped inside the tumor, patients may require lower dosages and endure fewer side effects. The technique is currently in animal testing, but hopefully it will be a valuable therapy for human patients in the future. (Image credit: Chemical & Engineering News; research credit: Y. Feng et al.; via AIP)

  • Leaping Mobulas

    Leaping Mobulas

    Mobula rays are second only to manta rays in size, and, unlike their larger cousins, relatively little is known about them. Like other rays, they propel themselves by flapping their large pectoral fins, and they generate thrust through hydrodynamic lift. They’re quite efficient swimmers, able to generate enough thrust to leap over 2 meters out of the water before flopping back into it. Why the mobula rays jump and why they seem to prefer belly-flopping is unclear. They may be using the slap and splash to communicate with one another. When aggregations of mobulas are observed from overhead, jumping seems to occur along the outside of the group. Maybe this is an effort to attract more mobulas to a group or a method of scaring prey into the midst of the hunting mobulas. In any case, it is spectacular to behold firsthand. (Image credit: BBC; source)

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    Martian Bees, Canopies, and Dandelion Seeds

    The latest FYFD/JFM video is out! May brings us a look at the incredible flight of dandelion seeds, numerical simulations that reveal the flow above forest canopies, and a look at bee-inspired flapping wing robots being developed for exploring Mars! Learn about all this in the video below, and, if you’ve missed other videos in the series, you can catch up here. (Image and video credit: N. Sharp and T. Crawford)

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    The Many Shapes of Fish

    After visiting an aquarium or snorkeling near a reef, you may have wondered why fish come in so many different shapes. Given that all fish species need to get around underwater, why are some fish, like tuna, incredibly streamlined while others, like the box fish, are so, well, boxy? There are several major groupings for fish based on their shape and how they propel themselves, whether it’s by undulating their body and tail or primarily by flapping their fins. Which grouping a fish tends toward depends largely on its environment and needs. Open-water swimmers tend to use their bodies and tails. Their bodies are better streamlined, too, allowing them to outrace even some ships! Fish that live in more complicated environments, like along the seafloor or in a reef, tend to favor maneuverability over speed. These fish – which include rays, pufferfish, and surgeonfish – use their fins for their main propulsion. Many of these species are still faster swimmers than you or I, but their slower speeds have reduced their need for hydrodynamic streamlining, allowing these fish to evolve a wide variety of odd body shapes. (Video credit: TED-Ed)

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    Bees, Squid, and Oil Plumes

    It’s time for another JFM/FYFD collab video! April’s video brings us a taste of spring with research on how bees carry pollen, squid-inspired robotics, and understanding the physics of underwater plumes like the one that occurred in the Deepwater Horizons spill eight years ago. Check it all out in the video below. (Image and video credit: T. Crawford and N. Sharp)

  • Can Zooplankton Mix Oceans?

    Can Zooplankton Mix Oceans?

    Krill and other tiny marine zooplankton make daily migrations to and from the ocean surface. Previously, models of ocean mixing ignored these migrations; these animals are tiny, researchers argued, so any effects they could have would be too small to matter. But zooplankton make these migrations in huge swarms, and studies of a laboratory analog of their migrations (using brine shrimp rather than krill) reveal that, when moving en masse, these tiny swimmers create turbulent jets and eddies far larger than an individual. Their collective motion is enough to mix salty water layers 1000 times faster than molecular diffusion alone! Learn more in the latest FYFD video, embedded below. (Image and video credit: N. Sharp; research credit: I. Houghton et al.; h/t to Kam-Yung Soh)

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    “Flowers and Colors”

    Many children have done the simple experiment of placing a cut flower in dyed water and watching as it changed color. The latest video from Beauty of Science relies on some related physics. Since the color of flowers typically depends on acidity, immersing a flower in dilute acid will change its color from pinks and purples to yellows and greens. Watching this transformation, we can learn about how fluids get transported through flowers.

    Like the leaves on a tree, flowers are covered in tiny cells called stomata that can open and close. In the daytime, stomata are typically open to allow carbon dioxide to diffuse into the plant. (At the same time, water pulled up from the roots is evaporating out the stomata, as seen previously.) Once immersed in acid, the open stomata are no longer bringing in carbon dioxide; instead, the acid is diffusing in and slowly spreading through the petals. In the timelapse video, some areas of the petal change faster than others. This could indicate more open stomata in the regions that change first or even that some areas inside the petal transport water (and acid) better than others. (Video and image credit: Beauty of Science; see also Making Of)

  • What Makes Joints Pop?

    What Makes Joints Pop?

    Cracking one’s knuckles produces an unmistakable popping noise that satisfies some and disconcerts others. The question of what exactly causes the popping noise has persisted for more than fifty years. It’s generally agreed that separating the two sides of a joint causes low enough pressures to form a cavitation bubble in the sinovial fluid of the joint. But researchers have been divided on whether it’s the formation or the collapse of this bubble that’s responsible for the sound. Studying the phenomenon firsthand is difficult with today’s imaging technologies – none of them are fast enough to capture a behavior that takes only 300 milliseconds. As a result, scientists are turning to mathematical modeling and numerical simulation.

    A recent study tackled the problem by modeling a joint that already contains a bubble and examining the bubble’s response to changes in pressure inside the joint. The pressure changes alter the bubble’s size and cause it to generate sound. When compared to experiments of people cracking their knuckles, the simulated sounds are remarkably similar in both amplitude and frequency. It’s not even necessary for the bubble to collapse completely to make the noise. Just a partial collapse is enough to sound just like that old, familiar pop. (Image credit: G. Kawchuk et al.; research credit: V. Chandran Suja and A. Barakat; via Gizmodo)

  • How Trees Pull Water

    How Trees Pull Water

    Trees are incredible organisms, and the physics behind them baffled scientists until relatively recently. Inside trees, there is a constant flow of water up from the roots, through the xylem and out the leaves. We often think of atmospheric pressure and capillary action as the mechanisms for pushing water up against the force of gravity, but this is not how trees work. Instead, the evaporation of water from the tree’s leaves actually pulls the entire water column up the tree. Water molecules really like sticking to one another, which actually allows them to hold together under this tension. 

    The result of all this pulling is a negative pressure inside the tree, and, with some clever manipulation, it’s possible to measure just how negative the pressure inside a tree is using a device called a pressure bomb. You can see the whole process in action in the Science IRL video below. The magnitude of a tree’s negative pressure fluctuates over a day, depending on how quickly it’s losing water, but typical values can range from 2-3 atmospheres of negative pressure to 17 or more! To get the equivalent (positive) pressure, you’d have to be nearly 2.7 kilometers under water. (Image and video credit: Science IRL)