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Astronomers measure solar corona’s magnetic field

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June 5 (UPI) — Astronomers have successfully measured the shape of the magnetic field in the solar corona, the outermost layer of the sun’s atmosphere.

Solar winds, streams of high-energy particles, radiate from the sun’s outer atmosphere. To understand space weather, scientists must understand the corona.

More powerful space observatories and advances in telescope instrument technology have helped scientists study the complexities of the sun’s atmosphere, but some solar phenomena can only be observed during a solar eclipse.

Using detailed observations of the corona, captured by telescopes during more than a dozen solar eclipses, scientists produced a large, high-resolution map of coronal magnetic field.

Scientists detailed the mapping effort this week in the Astrophysical Journal.

“The corona has been observed with total solar eclipses for well over a century, but never before had eclipse images been used to quantify its magnetic field structure,” lead author Benjamin Boe, graduate student at the University of Hawaii Institute for Astronomy, said in a news release. “I knew it would be possible to extract a lot more information by applying modern image processing techniques to solar eclipse data.”

Boe mapped the distribution of magnetic field lines revealed by observations captured during 14 different solar eclipses over the last 20 years. The mapping effort revealed highly structured patterns of magnetic fields.

The data also showed the corona’s magnetic field patterns shift over the course of the sun’s 11-year solar cycle.

During periods of limited solar activity, the corona’s magnetic field lines emerge at right angles, streaming directly out from the equator and poles. Field lines emanating from the mid-latitudes adopt a wider variety of angles.

When solar activity spikes, the corona’s magnetic field lines become more radial and less structured, spewing out in a variety of directions.

“We knew there would be changes over the solar cycle, but we never expected how extended and structured the coronal field would be,” Boe said. “Future models will have to explain these features in order to fully understand the coronal magnetic field.”

The new research could help scientists better understand the formation of solar winds, as well as the mechanisms that govern the trajectory of space weather once it leaves the sun’s atmosphere.

“These results are of particular interest for solar wind formation. It indicates that the leading ideas for how to model the formation of the solar wind are not complete, and so our ability to predict and defend against space weather can be improved,” said Boe.



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Sounds made by fluttering feathers help fork-tailed flycatchers communicate

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Sept. 22 (UPI) — Scientists have added another species to the list of birds that use sounds made with their feathers to communicate.

The male fork-tailed flycatcher, a passerine bird species native to the American tropics, creates unique sounds by fluttering its feathers at high frequencies, according to research published Wednesday in the journal Integrative and Comparative Biology.

“Back in the 1960’s, scientists noticed that they produce a distinctive sound only during a particular flight display,” researcher Christopher Clark, told UPI in an email.

“And those species of flycatcher in the genus Tyrannus, those that make the most distinctive sounds have the most distinctly shaped outer primary feathers,” said Clark, an associate professor of evolutionary biology at the University of California Riverside.

For the latest research, scientists conducted field studies to better understand both the mechanics of the feather fluttering and its communicative utility.

“We found that the birds don’t produce sounds every time they fly, but only under specific behavioral contexts,” lead study author Valentina Gomez told UPI in an email.

“One is during the pre-dawn display, after waking up. They begin displaying by singing and then they include feather songs. They also produce these sounds during territorial displays,” said Gomez, a doctoral student at the University of Illinois at Chicago.

To study the fluttering’s acoustic qualities, scientists captured males with mist netting, and used cameras and microphones to record the sounds the birds made as they escaped and retreated.

Fork-tailed flycatchers are quite territorial and aggressively defend their nests. Males are especially aggressive, regularly engaging in aerial battles with other males over mating opportunities and territory. They’re also more than willing to attack larger birds that stray too close to their nests.

Researchers used a taxidermy hawk outfitted with microphones and a camera to measure the movement of the fork-tailed flycatcher’s feathers during displays of aggression. The recordings revealed a difference in the sounds made by two subspecies, one that migrates long distances and another that is more stationary.

“Differences in migration likely influenced the shape of feathers and this affects the frequency at which they flutter,” Gomez said.

In effect, the two subspecies have developed dialects. Researchers suspect this phenomenon might help drive speciation, or species divergence.

“The evolution of different movement behaviors promotes the initial trigger of the speciation process,” Gomez said. “Through time, correlated evolution of morphological traits affects how they communicate.”

In other words, the difference in sound-making didn’t jumpstart the speciation process, but Gomez and her research partners hypothesize that the development of feather-flapping dialects works to reinforce the divergence.

Similarly, while the sound-making feathers of fork-tailed flycatchers may have initially evolved in response to pressures unrelated to communication, researchers claim the birds now utilize their sound-making abilities with intentionality. They’ve harnessed the power of their fluttering features for the purposes of communication.

“The birds alter how they are flapping their wings when they produce sound; their wingbeat frequency goes up by quite a bit,” Clark said. “The altered kinematics is another clue that this is ‘intentional.'”

While non-vocal communication has been observed in a variety of bird genus and species, scientists suspect the prevalence of the practice is underestimated.

Researchers hope that future investigations of feather-based communication among flycatchers will offer new insights into why so many birds have evolved non-vocal communication over and over again.

While the latest findings suggest the fork-tailed flycatcher relies on feather-based communication for pair bonding and displays of aggression, many questions about the fluttering’s utility remain.

“We still need to learn a lot about bird acoustic perception,” Gomez said.



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Once exposed to humans, animals start to lose their fear of predators

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Sept. 22 (UPI) — New research suggests animals begin to lose their fear of predators once they start encountering humans on a regular basis.

For the study, scientists surveyed the findings of 173 peer-reviewed papers on predator avoidance behaviors and traits deployed by 102 species of domesticated, captive and urbanized mammals, birds, reptiles, fish and mollusks.

The analysis, published Tuesday in the journal PLOS Biology, showed predator avoidance traits and behaviors, including vigilance, freezing and fleeing, decreased as a result of exposure to humans.

Researchers found individual variation in anti-predator characteristics increased upon a species’ initial exposure to humans, but then gradually decreased after generations of human exposure.

“While it is well known that the fact of being protected by humans decreases anti-predator capacities in animals, we did not know how fast this occurs and to what extent this is comparable between contexts,” lead researcher Benjamin Geffroy, biologist at the University of Montpellier in France, said in a news release.

The findings suggest behavioral flexibility allows for the initial increase in the variability of anti-predator traits, but researchers suspect genetic changes solidify declines in predator avoidance as subsequent generations adjust to the presence of humans.

In the studies analyzed by Geffroy and his colleagues, domesticated animals lose their anti-predator traits much more quickly than urbanized animals, which can cause problems when domesticated or urbanized species are released back into the wild.

“We also integrated physiological traits in the study but they were much less numerous that behavioral traits,” Geffroy said. “We believe they should be systematically investigated to draw a global pattern of what is happening at the individual level.

“We need more data to understand whether this occurs also with the mere presence of tourists,” Geffroy said.



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Search and rescue dogs fared well after work at 9/11 sites, study says

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Search and rescue dogs used during the 9/11 attacks lived as long as dogs not at the World Trade Center in New York City and the Pentagon, a new study finds.

“I was at Ground Zero and I would hear people make comments like, ‘Did you hear that half of the dogs that responded to the bombing in Oklahoma City died of X, Y, or Z?’ Or they’d say dogs responding to 9/11 had died,” said Dr. Cynthia Otto, director of the University of Pennsylvania’s Working Dog Center, in Philadelphia. “It was really disconcerting.”

Otto and her School of Veterinary Medicine colleagues’ findings are reassuring.

Dogs that participated in search-and-rescue efforts after 9/11 lived as long as search-and-rescue dogs not at the scene — a median of about 12.8 years, meaning half died sooner, half did not. They also outlived the life spans of their breed. There was no difference in the dogs’ cause of death.

“Honestly, this was not what we expected it’s surprising and wonderful,” said Otto, a veterinarian.

The researchers expected to see respiratory problems in the exposed dogs, but they did not. The most common cause of death was age-related conditions, such as arthritis and cancer.

For the study, Otto collected data on 95 dogs that had worked at the World Trade Center, the nearby Fresh Kills Landfill in Staten Island, N.Y., or Pentagon disaster sites in Washington, D.C. They compared these dogs with 55 search-and-rescue dogs that were not deployed on 9/11.

“We anticipated that the dogs would be the ‘canary in the coal mine’ for the human first responders since dogs age faster than humans and didn’t have any of the protective equipment during the response,” Otto said in a university news release. “But we didn’t see a lot that was concerning.”

Generally, these dogs are stronger and healthier than pets, which might partly explain why the dogs fared well, she said.

The findings were published Sept. 21 in the Journal of the American Veterinary Medical Association.

More information

For more on responder health after 9/11, visit the New York State Department of Health.

Copyright 2020 HealthDay. All rights reserved.



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