Search results for: “art”

Extreme Weather and Climate Change
Extreme weather events like floods, hurricanes, atmospheric rivers, heat waves, and droughts are increasingly discussed in terms of the effects of climate change. Because complex systems have complex causes, it’s difficult to draw exact lines of causality between human-made climate change and a given weather event. But scientists have built an array of tools that help address two key questions: 1) how much more extreme was this weather due to climate change, and 2) how much more likely was this extreme event due to climate change?
Comparing (a) the actual flooding from Hurricane Harvey with (b) the estimated flood that would have occurred without climate change. The depth of actual flood waters was about 1m greater due to climate change.
To answer the first question, scientists often use hindcasts. In these studies, scientists first build a simulation that mirrors the actual event, like Hurricane Harvey’s stall over Houston, Texas. Once their simulated storm reflects the actual one, they tweak the initial conditions to reflect a world without climate change and see how the storm differs. By comparing the actual and simulated floods (image above), scientists can estimate just how much worse climate change made things. In Harvey’s case, they found that human activity increased the overall precipitation by 19% and that 32% of the flooded homes in Harris county would not have flooded in a world without climate change. Detailed results from that particular study can be explored in the web portal here. (Image credits: Flooded street – J. Gade, Harvey flooding – M. Wehner; research credit: M. Wehner in Physics Today)
November 27, 2023
Ghosts of Rivers Past
Artist Dan Coe uses lidar data to create portraits of rivers and their past meanders. Used aerially, lidar produces high-resolution elevation data that provides a glimpse of features that are currently hidden beneath vegetation. With rivers, this means unearthing some of their previous paths. Secondary flows in a river bend erode the bed so that the bend gets more and more strongly curved. Eventually, the river can double back on itself and cut off the long curve. Repeat that process over millennia and you wind up with the complex paths in Coe’s images. (Image credit: D. Coe; via Colossal)
November 24, 2023
Linking Size and Origin in Droplets
Respiratory diseases like measles, flu, tuberculosis, and COVID-19 are all transmitted by droplets. Some are tiny and airborne, capable of traveling long distances. Other drops are larger and only capable of traveling short distances. A new review paper consolidates what we know about these droplets and categorizes them by size and origin.
It turns out that a droplet’s size can tell us where it originated in the body. The largest type of droplets come from our mouths, lips, and tongues. Some form from filaments of saliva that stretch across our mouths and burst during exhalation. Others originate in our nasal passages where a sneeze can destabilize the mucus film there. These types of droplets are best suited to transmitting diseases that reside in the upper respiratory tract. Coughing, sneezing, singing, and speaking all produce these droplets, but breathing does not.
In contrast, the smallest classes of droplets come from the bronchial passages of the lungs, where films form after exhalation closes a passage. When we inhale again, the passage reopens, the film breaks up, and tiny droplets flow further into the lungs before getting exhaled. Breathing alone is enough to create and spread these tiny droplets, which are well-suited to spreading diseases that reside deep in the lungs, like tuberculosis.
In between these extremes are medium-sized droplets created from movement around our vocal cords. The formation mechanism for these droplets is least understood, but they are connected to breathing, coughing, speaking, singing, and so on.
Ultimately, understanding the mechanics of disease transmission is about knowing how to best prevent transmission. Knowing the size of droplets responsible for transmission lets us prioritize responses that work. For example, if large droplets are the primary transmission mechanism, loose-fitting masks and face masks will stop the spread. But for smaller droplets, ventilation measures and well-fitted N-95 respirators are the better choice. (Image credit: Anton; research credit: M. Pöhlker et al.; via APS Physics)
November 22, 2023
An August Arc
In summer, the fjords of Greenland are littered with ice, but in August 2023, satellites caught an odd interloper. See the thin white arc spanning the fjord in the photo above? Scientists suspect this ephemeral feature was a wave caused by a large iceberg calving off the glacier on the right. When large chunks of ice fall into the water, they can cause distinctive waves that travel out from the point of impact.
Another possible mechanism is an underwater plume. In Greenland’s fjords, such plumes are sometimes formed from freshwater melting below the glacier. When that water rises to the surface, it can push ice. (Image credit: W. Liang; via NASA Earth Observatory)
November 21, 2023
A Better Ear Plug
Ear plugs can be wonderful at blocking outside noise, but they come with a downside: they typically amplify internal bodily sounds, like our heartbeat, breathing, and chewing. This effect, called occlusion, is distracting enough for some users to forego ear protection or hearing aids. But a new prototype offers a hope for an occlusion-free future without requiring active noise-cancelling.
Most devices fit a short way inside our ear canals, which blocks outside sound well, but creates a little resonance chamber between the plug and our ear drums. It’s this gap that amplifies the low-frequency sounds within our bodies, making them seem much louder. To counter that, the team’s new plug contains foam sections arranged with hollow spaces between. By tuning the properties of the 3D-printed foam, they created a resonant structure inside the earbud that damps out those low-frequency body noises while still blocking outside sound.
Illustration of the earbud’s interior. The blue and green areas are foam-filled cavities.
So far the prototype has only been tested with an artificial ear designed for auditory tests; that’s enough to show that the concept works, but next they’ll redesign the bud to fit a human ear canal more comfortably. (Image and research credit: K. Carillo et al.; via APS Physics)
November 20, 2023
Slumping Ceramics
Dripping, drooping pottery is artist Philip Kupferschmidt’s specialty. Covered in drips and drops, slumping as if half-melted, Kupferschmidt’s ceramics seem partially liquid. With their colorful glazes, these pieces ooze personality. (Image credit: P. Kupferschmidt; via Colossal)
November 17, 2023
Understanding Cyanobacteria
Over 2 billion years ago, cyanobacteria emerged as Earth’s first photosynthesizing organisms. Today they are widespread and critical contributors to both carbon and nitrogen cycles. Colonies can form large mats, like those pictured above, but, even at the microscale, cyanobacteria are actively forming patterns among individual bacteria. A recent study considers cyanobacteria as active matter.
At the microscopic scale, cyanobacteria form different patterns, depending on their density.
By simulating the cyanobacteria as filaments that interact through a series of simple rules, the researchers were able to reproduce the complex patterns bacterial colonies form. Their physical model also offered an explanation — based on the relative importance of advective and diffusive transport — for the characteristic length scales found in the bacterial patterns. (Image credit: Yellowstone – B. Cappellacci, patterns – M. Faluweki et al.; research credit: M. Faluweki et al.; via APS Physics)
November 15, 2023
Shifting Sands
Qinghai Lake sits in western China, where a warmer and wetter climate has been raising the lake’s water level in recent years. These two satellite images, from 2010 and 2022, show the effects of those changes. Sand spits that once separated the smaller Shadao Lake from the surrounding lake have worn away and sunk, rejoining the two bodies of water.
Why is the area’s warmer climate also wetter? The lake has risen due to increased precipitation and river run-off feeding it, but it’s also seen less evaporation. So far the area’s temperature increases have been most notable in winter months, when the lake is covered in ice. In contrast, the summers have been wetter, which means more cloudy days and less chance for evaporation. (Image credit: A. Nussbaum, modified by N. Sharp; via NASA Earth Observatory)
November 14, 2023
Swimming Through Mud
At the bottom of ponds, nematodes and other creatures swim in a world of mud. They squirm their way through a sediment of dirt particles suspended in water. Mud, of course, is notoriously impossible to see through, so to understand these creatures’ movements, scientists turn instead to biorobotics. Here, a team uses a magnetic head attached to an elastic tail to mimic these tiny creatures.
To drive the robot’s motion, they use an oscillating magnetic field, which forces the magnetic head to rotate. Combined with the elastic tail and the drag caused by surrounding materials, this causes the robot to swim in a fashion similar to its biological inspirations.
A biomimetic robot swims through immersed grains. The robot’s magnetic head is forced with an oscillating magnetic field. It swims through an underwater bed of hydrogel beads, with diameters smaller than that of the robot’s head.
To mimic the muddy environment of a pond’s bottom, scientists used a bed of hydrogel beads immersed in water. Looking at the experimental video above, you’ll see no sign of the beads. That’s because the hydrogel beads have nearly the same index of refraction as water. Once you pour water in, they seem to disappear. That allows the researchers to focus instead on the robot’s motion. In other experiments, they added dye to the beads so that they could see how they moved around the robot.
They found that the robot’s motion fluidizes the grains around it. Effectively, the robot’s motion creates an area with fewer grains and more water for it to move through. Once it’s passed, however, more grains settle in, and the bed returns to a denser packing. (Image credit: nematode – P. Garcelon, experiment – A. Biswas et al.; research credit: A. Biswas et al.)
November 13, 2023
Withstanding Rocket Launches
It takes a lot of power to lift a giant rocket‘s payload all the way to orbit, and in the first moments of a rocket launch, all that energy is directed downward at a concrete pad. How do engineers design and protect launch pads? In this Practical Engineering video, Grady tackles just that question through a comparison of SpaceX’s Stage Zero and NASA’s Launch Pad 39A.
SpaceX notoriously chose to build Stage Zero without a trench or water sprayer system like the ones NASA use. Trenches deflect the rocket exhaust to reduce the impact on infrastructure beneath the engines. And water sprayers reduce the temperatures the pad experiences and disrupt shock waves that otherwise hammer the pad. Without those precautions, even special heavy-duty concretes have a hard time holding together against a launch. (Video and image credit: Practical Engineering)
November 9, 2023

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