Science360 News Service: Picture of the Day

Virtual 'UniverseMachine' sheds light on galaxy evolution

Wed, 04 Sep 2019 07:00:00 GMT

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How do galaxies such as our Milky Way come into existence? How do they grow and change over time? The science behind galaxy formation has long been a puzzle, but a University of Arizona-led team of scientists is one step closer to finding answers, thanks to supercomputer simulations. Observing real galaxies in space can only provide snapshots in time, so researchers who study how galaxies evolve over billions of years need to use computer simulations. Traditionally, astronomers have used simulations to invent theories of galaxy formation and test them, but they have had to proceed one galaxy at a time. Peter Behroozi of the university's Steward Observatory and colleagues overcame this hurdle by generating millions of different universes on a supercomputer, each according to different physical theories for how galaxies form. The findings challenge fundamental ideas about the role dark matter plays in galaxy formation, the evolution of galaxies over time and the birth of stars. The study is the first to create self-consistent universes that are exact replicas of the real ones -- computer simulations that each represent a sizeable chunk of the actual cosmos, containing 12 million galaxies and spanning the time from 400 million years after the Big Bang to the present day. The results from the "UniverseMachine," as the authors call their approach, have helped resolve the long-standing paradox of why galaxies cease to form new stars even when they retain plenty of hydrogen gas, the raw material from which stars are forged. The research is partially funded by NSF's Division of Physics through grants to UC Santa Barbara's Kavli Institute for Theoretical Physics and the Aspen Center for Physics.

Image credit: NASA/ESA/J. Lotz and the HFF Team/STScI

Scientists recover the first genetic data from an extinct bird in the Caribbean

Tue, 03 Sep 2019 07:00:00 GMT

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Scientists have recovered the first genetic data from an extinct bird in the Caribbean, thanks to the remarkably preserved bones of a Creighton's caracara in a flooded sinkhole on Great Abaco Island in the Bahamas. Studies of ancient DNA from tropical birds have faced two formidable obstacles. Organic material quickly degrades when exposed to heat, light and oxygen. And birds' lightweight, hollow bones break easily, accelerating the decay of the DNA within. But the dark, oxygen-free depths of a 100-foot blue hole known as Sawmill Sink provided ideal preservation conditions for the bones of Caracara creightoni, a species of large carrion-eating falcon that disappeared soon after humans arrived in the Bahamas about 1,000 years ago. Florida Museum of Natural History researcher Jessica Oswald and her colleagues extracted and sequenced genetic material from the 2,500-year-old C. creightoni femur. Because ancient DNA is often fragmented or missing, the team had modest expectations for what they would find –- maybe one or two genes. But instead, the bone yielded 98.7% of the bird's mitochondrial genome, the DNA most living things inherit from their mothers. The mitochondrial genome showed that C. creightoni is closely related to the two remaining caracara species alive today: the crested caracara and the southern caracara. The three species last shared a common ancestor between 1.2 and 0.4 million years ago. "This project enhanced our understanding of the ecological and evolutionary implications of extinction, forged strong international partnerships, and trained the next generation of researchers," says Jessica Robin, a program director in National Science Foundation's Office of International Science and Engineering, which funded the study.

Image credit: Florida Museum photo by Kristen Grace

Lemurs find love at first whiff

Fri, 30 Aug 2019 07:00:00 GMT

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Many people turn to the Internet to find a Mr. or Ms. Right. But lemurs just give their potential partners a sniff. A study of lemur scents has found that an individual’s distinctive body odor reflects genetic differences in their immune system, and that other lemurs can detect these differences by smell. From just one whiff, these primates can tell which prospective partners have immune genes different from their own. The ability to sniff out mates with different immune genes could make their offspring’s immune systems more diverse and able to fight more pathogens. Shown here: Fritz the ring-tailed lemur sniffs a tree for traces of other lemurs’ scents.

Image credit: David Haring/Duke Lemur Center

Could graphene-lined clothing prevent mosquito bites?

Thu, 29 Aug 2019 07:00:00 GMT

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A new study shows that graphene sheets can block the signals mosquitoes use to identify a blood meal, potentially enabling a new chemical-free approach to mosquito bite prevention. Researchers showed that multilayer graphene can provide a twofold defense against mosquito bites. The ultra-thin yet strong material acts as a barrier that mosquitoes are unable to bite through. At the same time, experiments showed that graphene also blocks chemical signals mosquitoes use to sense that a blood meal is near, blunting their urge to bite in the first place. The findings suggest that clothing with a graphene lining could be an effective mosquito barrier.

Image credit: Hurt Lab/Brown University

Genetic redundancy aids competition among symbiotic bacteria in squid

Wed, 28 Aug 2019 07:00:00 GMT

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The molecular mechanism used by many bacteria to kill neighboring cells has redundancy built into its genetic makeup, which could allow for the mechanism to be expressed in different environments, say researchers at Penn State and the University of Wisconsin-Madison. Their new study provides insights into the molecular mechanisms of competition among bacteria. "Many organisms, including humans, acquire bacteria from their environment," said Tim Miyashiro, a biochemist and molecular biologist at Penn State and the leader of the research team. "These bacteria can contribute to functions within the host organism, like how our gut bacteria help us digest food. We're interested in the interactions among bacteria cells, and between bacteria and their hosts, to better understand these mutually beneficial symbiotic relationships." Cells of the bioluminescent bacteria Vibrio fisheri take up residence in the light organ of newly hatched bobtail squid. At night, the bacteria produce a blue glow that researchers believe obscures a squid's silhouette and helps protect it from predators. The light organ has pockets, or crypts, in the squid's skin that provide nutrients and a safe environment for the bacteria. "When the squid hatches, it doesn't yet have any bacteria in its light organ," said Miyashiro. "But bacteria in the environment quickly colonize the squid's light organ." Some of these different bacteria strains can coexist, but others can't. "Microbial symbioses are essentially universal in animals, and are crucial to the health and development of both partners," says Irwin Forseth, a program director in the National Science Foundation's Division of Integrative Organismal Systems, which funded the research. "The results from this study highlight the role small genetic changes can play in microbe interactions. Increased understanding will allow us to better predict organisms' performance in changing environments."

Image credit: Andrew Cecere

Why animals eat what they eat

Tue, 27 Aug 2019 07:00:00 GMT

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What an animal eats is a fundamental aspect of its biology, but surprisingly, the evolution of diet had not been studied across the animal kingdom until now. Scientists at the University of Arizona report several unexpected findings from taking a deep dive into the evolutionary history of more than one million animal species and going back 800 million years, when the first animals appeared on our planet. The study revealed several surprising key insights: Many species living today that are carnivorous, meaning they eat other animals, can trace this diet back to a common ancestor more than 800 million years ago; A plant-based, or herbivorous, diet is not the evolutionary driver for new species that it was believed to be; Closely related animals tend to share the same dietary category -- plant-eating, meat-eating, or both. This finding implies that switching between dietary lifestyles is not something that happens easily and often over the course of evolution.

Image credit: Daniel Stolte/UANews

What's killing sea otters? Scientists pinpoint parasite strain

Mon, 26 Aug 2019 07:00:00 GMT

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Many wild southern sea otters in California are infected with the parasite Toxoplasma gondii, yet the infection is fatal for only a fraction of sea otters, which has long puzzled the scientific community. A National Science Foundation-funded study identifies the parasite's specific strains that are killing southern sea otters, tracing them back to a bobcat and feral domestic cats from nearby watersheds. The study marks the first time a genetic link has been clearly established between the Toxoplasma strains in felid hosts and parasites causing fatal disease in marine wildlife. The study's results highlight how infectious agents like Toxoplasma can spread from cat feces on land to the sea, leading to detrimental impacts on marine wildlife.

Image credit: Trina Wood/UC Davis

Maya more warlike than previously thought

Fri, 23 Aug 2019 07:00:00 GMT

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The Maya of Central America are thought to have been a kinder, gentler civilization, especially compared to the Aztecs of Mexico. At the peak of Mayan culture some 1,500 years ago, warfare seemed ritualistic, designed to extort ransom for captive royalty or to subjugate rival dynasties, with limited impact on the surrounding population. Only later, archeologists thought, did increasing drought and climate change lead to total warfare -- cities and dynasties were wiped off the map in so-called termination events -- and the collapse of the lowland Maya civilization around 1,000 A.D. (or C.E., current era). New evidence unearthed by National Science Foundation-funded researchers call all this into question, suggesting that the Maya engaged in scorched-earth military campaigns -- a strategy that aims to destroy anything of use, including cropland -- even at the height of their civilization, a time of prosperity and artistic sophistication. The finding also indicates that this increase in warfare, possibly associated with climate change and resource scarcity, was not the cause of the disintegration of the lowland Maya civilization.

Image credit: Francisco Estrada-Belli/Tulane

Brookhaven completes LSST's digital sensor array

Thu, 22 Aug 2019 07:00:00 GMT

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After 16 years of dedicated planning and engineering, scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have completed a 3.2 gigapixel sensor array for the camera that will be used in the Large Synoptic Survey Telescope (LSST), a massive telescope that will observe the universe like never before. The digital sensor array is composed of about 200 16-megapixel sensors, divided into 21 modules called "rafts." Each raft can function on its own, but when combined, they will view an area of sky that can fit more than 40 full moons in a single image. Researchers will stitch these images together to create a time-lapse movie of the complete visible universe accessible from Chile. Currently under construction on a mountaintop in Chile, LSST is designed to capture the most complete images of our universe that have ever been achieved. The project to build the telescope facility and camera is a collaborative effort among more than 30 institutions from around the world, and it is primarily funded by DOE's Office of Science and the National Science Foundation.

Image credit: SLAC National Accelerator Laboratory

Facial recognition technique could improve hail forecasts

Wed, 21 Aug 2019 07:00:00 GMT

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The same artificial intelligence technique typically used in facial recognition systems could help improve prediction of hailstorms and their severity, according to a new, National Science Foundation-funded study. Instead of zeroing in on the features of an individual face, scientists trained a deep learning model called a convolutional neural network to recognize features of individual storms that affect the formation of hail and how large the hailstones will be, both of which are notoriously difficult to predict. The promising results highlight the importance of taking into account a storm's entire structure, something that's been challenging to do with existing hail-forecasting techniques.

Image credit: Carlye Calvin