April 24, 2024

How large streaks of water leap from the surface of the water

DART removed boulders from asteroid Dimorphos

NASA’s DART (Double Asteroid Redirect Test) spacecraft intentionally crashed into the asteroid Dimorphos on September 27, 2022, changing its orbit around the larger asteroid Didymos as a result.

Now, there is NASA’s Hubble Space Telescope he found out a swarm of 37 boulders, flowing at speeds of less than 1km/h, which could be shaken loose from the surface of the asteroid in the process.

Image of the asteroid Dimorphos, with compass arrows, scale bar, and color key for reference…. The north and east compass arrows show the orientation of the image on the sky. Dimorphos is the bright white object in the lower left. It has a dusty bluish tail that runs diagonally to the upper right. The asteroid is surrounded by a cluster of blue dots (marked with white circles). These are boulders knocked off the asteroid when, on September 26, 2022, NASA purposely rammed the half-ton DART impactor spacecraft into the asteroid as a test of what it would take to deflect some future asteroid from hitting Earth. The slow-moving boulders were photographed by Hubble using the Wide Field Camera 3 in December 2022. The color results from assigning a blue hue to the monochromatic (grayscale) image.

“This is a great observation – much better than I expected. We see a cloud of boulders carrying mass and energy away from the impact target. The number, sizes and shapes of the boulders are consistent with the impact they had when they were removed from the surface of Dimorphos,” says Professor David Jewitt, a planetary scientist from the University of California, Los Angeles, in the USA.

“This tells us for the first time what happens when you hit an asteroid and you see material coming out to the largest sizes. The boulders are some of the faintest objects ever imaged within our solar system.”

Revealing the map of our intestinal neighborhoods

Researchers have produced an ultra-high-resolution map of the types of cells that make up the digestive system, and published the results in a new study in nature.

“This is the first time anyone has made a spatial map of the intestine at the single-cell level,” says Michael Snyder, Professor and Chair of Genetics at Stanford Medicine in the US, and co-senior author of the research.

“Our maps are designed as a reference for a healthy gut, against which we can compare everything from irritable bowel disease to early stage colon cancer.

“This will form the basis of our understanding of all types of digestive diseases.”

Stained fluorescent microscope image of intestinal cells
These images are produced using advanced imaging techniques that enable us to study the cells found in the human intestine. Using a combination of microscopy and robotic technology, these scientific visualizations provide a window into the complex world of cell diversity. The different colors in the image represent specific molecules that are expressed within different cell types. These molecules, like proteins, play a vital role in determining the identity and function of each cell within the intestine. By “painting” or “tagging” individual cells with different colors, valuable insights are gained into the complex interactions and structures within our intestines. In this particular image, each color corresponds to a specific molecule, providing information about the presence and distribution of different cell types or structures. Credit: Stanford Medicine/Snyder lab/Greenleaf lab/Nolan lab

By pinpointing where each type of cell is located, and which other cells are associated with them, they were able to investigate how the organization of healthy tissue changes throughout the digestive tract.

The study was carried out using samples from the small and large intestines of nine deceased adult donors – most of them white and male – so the next steps are to increase the diversity of the samples.

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Credit: Stanford Medicine/Snyder lab/Greenleaf lab/Nolan lab

How do the world’s largest water striders jump on water?

Water striders are a family of insects that have adapted to live on top of still water due to their long hydrophobic legs. Their feet support their bodies on the surface without breaking it, with the surface of the water bending to create a dimple, or meniscus, below.

When small aquatic species escape attacks from underwater predators, they use each dimple as a mini-trampoline to jump up while using enough force to avoid breaking the surface.

Now, new research the world’s largest water strider, the giant water strider (Gigantometer gigas), uses a different mechanism.

The clip shows an example of the giant water strider jumping up. The movements are slowed down (0.0375 normal speed). The second smaller water strider belongs to the genus Ptilomera. Credit: Piotr G Jablonski, Woojoo Kim, and coauthors Allometry of jumping on water by water striders. Some rights reserved (CC BY-SA 4.0)

High-speed videos showed that this heaviest species breaks the surface of the water when they jump; when the legs break the surface of the water they move down, surrounded by a layer of air trapped around their long leg hairs. This causes drag, which propels them in the opposite direction (upwards) in the second phase of the jump.

They developed a mathematical model that predicted that all jumping spiders would be heavier than about 80 mg using this method to find the speed that can protect them from the attack of the fish.

“This discovery is interesting from both engineering and evolutionary perspectives because it provides inspiration for water-walking robots and establishes a solid theoretical basis for future comparative analyzes of multiple species of water striders to understand the coevolution of body size and jumping mechanism in water striders,” the authors wrote in their paper. PNAS.

The clip shows an example of the giant water strider jumping up and filmed closer to you. The water streaker leaves the field of view. The movements are slowed down (0.125 normal speed). Credit: Piotr G Jablonski, Woojoo Kim, and coauthors Allometry of jumping on water by water striders. Some rights reserved (CC BY-SA 4.0)

Are Japanese encephalitis spread by litter chickens?

The largest Japanese encephalitis virus outbreak recorded in Australia was in 2021 and 2022, with 45 human cases and seven deaths. The disease is a form of encephalitis, or inflammation of the brain, and is caused by an RNA virus that is spread by insects such as ticks and mosquitoes.

Wild waterfowl act as a reservoir for the virus, as the virus replicates to levels high enough to infect a mosquito that bites it.

Native Australian ibises (Molucca Threskiornis), commonly known as litter chickens, were implicated in the outbreak among other birds. But because they are common in urban centers, they may play a role in the spread of Japanese encephalitis and other important pathogens.

Researchers at the Australian Center for Disease Preparedness CSIRO are now using genomics to investigate whether this is the case.



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