Category Archives: University of Chicago

See the crazy way octopus and cuttlefish get spiky

A new study clarifies an amazing defense tactic of octopus and cuttlefish: the ability to erect 3D spikes out of their skin, hold them for an hour, then quickly retract them and swim away.

New information about the neural and muscular mechanisms that underlie this extraordinary defense tactic appears in the journal iScience.

“The biggest surprise for us was to see that these skin spikes, called papillae, can hold their shape in the extended position for more than an hour, without neural signals controlling them,” says Paloma Gonzalez-Bellido, a lecturer in neuroscience at University of Cambridge and a former staff scientist at the University of Chicago’s Marine Biological Laboratory.

This sustained tension, the team found, arises from specialized musculature in papillae that is similar to the “catch” mechanism in clams and other bivalves.

“The catch mechanism allows a bivalve to snap its shell shut and keep it shut, should a predator come along and try to nudge it open,” says corresponding author Trevor Wardill, a research fellow at the University of Cambridge and a former staff scientist at the MBL. Rather than using energy to keep the shell shut, the tension is maintained by smooth muscles that fit like a lock-and-key, until a chemical signal (neurotransmitter) releases them. A similar mechanism may be at work in cuttlefish papillae, the scientists found.

Gonzalez-Bellido and Wardill began this study in 2013 in the laboratory of Roger Hanlon, an MBL senior scientist and the leading expert on cephalopod camouflage. Hanlon’s lab had been the first to describe the structure, function, and biomechanics of skin-morphing papillae in cuttlefish (Sepia officinalis), but their neurological control was unknown.

Hanlon suggested the team look for the “wiring” that controls papillae action in the cuttlefish. As reported here, they discovered a motor nerve dedicated exclusively to papillary and skin tension control that originates not in the brain, but in a peripheral nerve center called the stellate ganglion.

Surprisingly, they also found that the neural circuit for papillae action is remarkably similar to the neural circuit in squid that controls skin iridescence. Since cuttlefish don’t have tunable iridescence, and squid don’t have papillae, this finding raises interesting questions about the evolution and function of the neural circuit in different species.

“We hypothesize that the neural circuit for iridescence and for papillae control originates from a common ancestor to squid and cuttlefish, but we don’t know that yet. This is for future work,” Gonzalez-Bellido says.

via GIPHY

“This research on neural control of flexible skin, combined with anatomical studies of the novel muscle groups that enable such shape-shifting skin, has applications for the development of new classes of soft materials that can be engineered for a wide array of uses in industry, society, and medicine,” Hanlon says.

Source: University of Chicago

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We’re more willing to try ‘gross’ foods with foreign names

People are more willing to eat foods that they find disgusting if those foods are presented in a foreign language, new research shows.

The finding could help win acceptance for environmentally sustainable foods that many people are unwilling to try.

“By using a foreign language you take away some of the emotionality attached to ‘insects…’”

Americans and Europeans are generally averse to eating insects or artificial meat, for example. Likewise, drinking water made by purifying wastewater has been a tough sell.

“In people’s minds, once in contact (with a disgusting entity), always in contact,” says Janet Geipel, a postdoctoral scholar in the University of Chicago lab of Boaz Keysar and the lead author of the study in Nature Sustainability.

“No matter how good your technology is, it will not convince these people. So, we need psychology to nudge sustainable consumption. And one nudge could be presenting sustainable-but-disgusting products in a foreign language,” Geipel explains.

Geipel and her European collaborators were inspired by research, including work done by Keysar and his group, showing that encountering emotionally charged matters in a foreign language reduces people’s emotional reaction to them.

They did three separate studies, testing reactions to recycled wastewater, cookies made from mealworms, and artificial meat. Participants were native speakers of German, Italian, and Dutch who had learned either English or German as a second language. The participants read about the product either in their native tongue or their second language and were then asked if they would be willing to eat or drink it.

Of those who encountered the products in their native tongue, only about 18 percent says they would be willing to try either artificial meat or mealworm cookies. Forty percent ruled out the meat entirely, and almost 55 percent says an absolute “no” to the cookies. When presented with the products in their second language, however, only 25.8 percent completely ruled out the artificial meat, and 35.5 percent says “never” to the mealworm cookies.

Encountering the recycled wastewater in a foreign language increased participants’ willingness to give it a try by 12 percent.

“I think the increase was maybe stronger for products that they don’t like to begin with,” says Geipel. “And artificial meat and insect-based foods are especially aversive to Europeans.”

Language sways answer to ‘kill 1, save 5’ train dilemma

The wastewater study also looked at actual consumption. Both groups of participants were asked how recently they drank something and were offered a glass of what was purportedly recycled wastewater (actually ordinary tap water). This time the effect of language was marginal, and was modulated by the participants’ thirst.

Geipel plans further work using a simple foreign-language label for the aversive foods rather than an entire description. If it works, such an intervention would be more widely applicable, as many people do not speak a foreign language. She and her colleagues feel that language interventions have potential for helping make some aversive sustainable foods more acceptable.

“You can use language to reduce feelings of disgust related to some products that are rejected by the population,” Geipel says.

“A native tongue has a higher emotional resonance than a foreign language because it is used more often and in more emotional contexts. By using a foreign language you take away some of the emotionality attached to ‘insects’, and thus help override a barrier that prevents the consumption of insect-based food.”

Source: Carla Reiter for University of Chicago

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We share some spine-healing genes with lampreys

Many of the same genes that lampreys have that allow for natural repair of injured spinal cords are also active in the repair of the peripheral nervous system in mammals, including humans, a new study indicates.

The findings are consistent with the possibility that in the long term, the same or similar genes may be harnessed to improve spinal cord injury treatments in people.

“We found a large overlap with the hub of transcription factors that are driving regeneration in the mammalian peripheral nervous system,” says Jennifer Morgan, director of the Marine Biological Laboratory at the University of Chicago.

Lampreys are jawless, eel-like fish that shared a common ancestor with humans about 550 million years ago. The study, which appears in Nature Scientific Reports, arose from discovering that a lamprey can fully recover from a severed spinal cord without medication or other treatment.

“They can go from paralysis to full swimming behaviors in 10 to 12 weeks,” Morgan says.

“Scientists have known for many years that the lamprey achieves spontaneous recovery from spinal cord injury, but we have not known the molecular recipe that accompanies and supports this remarkable capacity,” says Ona Bloom of the Feinstein Institute for Medical Research and the Zucker School of Medicine at Hofstra/Northwell, who is a former MBL Whitman Center fellow.

“In this study, we have determined all the genes that change during the course of recovery and now that we have that information, we can use it to test if specific pathways are actually essential to the process,” Bloom says.

Nanoparticle injection could cut damage after spine injury

The researchers followed the lampreys’ healing process and took samples from the brains and spinal cords at multiple points in time, from the first hours after injury until three months later when they were healed and then analyzed the material to determine which genes and signaling pathways were activated as compared to a non-injured lamprey.

As expected, they found many genes in the spinal cord that change over time with recovery. Further, somewhat unexpectedly, they also discovered a number of injury-induced gene expression changes in the brain.

“This reinforces the idea that the brain changes a lot after a spinal cord injury,” Morgan says. “Most people are thinking, ‘What can you do to treat the spinal cord itself?’ but our data really support the idea that there’s also a lot going on in the brain.”

They also discovered that many of the genes associated with spinal cord healing are part of the Wnt signaling pathway, a set of proteins that play a role in tissue development.

‘Knit’ severed spinal cords with graphene ribbons

“Furthermore, when we treated the animals with a drug that inhibits the Wnt signaling pathway, the animals never recovered their ability to swim,” Morgan says. Future research will explore why the Wnt pathway seems particularly important in the healing process.

Jeramiah Smith of the University of Kentucky and Joseph Buxbaum of the Icahn School of Medicine at Mount Sinai, both former Whitman Center fellows, collaborated on the study.

Source: University of Chicago

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The Milky Way ate 11 other galaxies

Astronomers have discovered 11 new stellar streams—remnants of smaller galaxies torn apart and devoured by our Milky Way.

The finding is among the highlights of the first three years of survey data from the Dark Energy Survey—research on about 400 million astronomical objects, including distant galaxies as well as stars in our own galaxy.

Dark Energy Survey field of view
This image shows the entire Dark Energy Survey field of view—roughly one-eighth of the sky—captured by the Dark Energy Camera, with different colors corresponding to the distance of stars. (Blue is closer, green is farther away, red is even farther.) Several stellar streams are visible in this image as yellow, blue, and red streaks across the sky. (Credit: Dark Energy Survey)

The Dark Energy Survey, a collaboration that aims to reveal the nature of the mysterious force of dark energy, announced the results.

The Dark Energy Survey

The data cover about 5,000 square degrees, or one-eighth of the entire sky, and include roughly 40,000 exposures taken with the Dark Energy Camera. The images correspond to hundreds of terabytes of data and are being released along with catalogs of hundreds of millions of galaxies and stars.

“We can use these streams to measure the amount, distribution, and ‘clumpiness’ of dark matter in the Milky Way.”

“There are all kinds of discoveries waiting to be found in the data,” says Brian Yanny of Fermi National Accelerator Laboratory, and Dark Energy Survey data management project scientist.

“While DES scientists are focused on using it to learn about dark energy, we wanted to enable astronomers to explore these images in new ways, to improve our understanding of the universe,” Yanny says.

The Dark Energy Camera, the primary observation tool of the Dark Energy Survey, is one of the most powerful digital imaging devices in existence. It was built and tested at Fermilab, the lead laboratory on the Dark Energy Survey, and is mounted on the National Science Foundation’s 4-meter Blanco telescope in Chile. A team at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign then processes the DES images.

A growing galaxy

One new discovery enabled by the data set is the detection of 11 new streams of stars around our Milky Way.

Our home galaxy is surrounded by a massive halo of dark matter, which exerts a powerful gravitational pull on smaller, nearby galaxies. The Milky Way grows by pulling in, ripping apart, and absorbing these smaller systems. As stars are torn away, they form streams across the sky that the Dark Energy Camera can detect.

Is the Milky Way actually kind of weird?

Even so, stellar streams are extremely difficult to find since they are composed of relatively few stars spread out over a large area of sky.

“It’s exciting that we found so many stellar streams,” says astrophysicist Alex Drlica-Wagner of Fermilab and the Kavli Institute for Cosmological Physics at University of Chicago. “We can use these streams to measure the amount, distribution, and ‘clumpiness’ of dark matter in the Milky Way. Studies of stellar streams will help constrain the fundamental properties of dark matter.”

Prior to the new discoveries, only about two dozen stellar streams had been discovered. Many of them were found by the Sloan Digital Sky Survey, a precursor to the Dark Energy Survey. The effort to detect new stellar streams in the Dark Energy Survey was led by Nora Shipp, a graduate student at the University of Chicago.

“We’re interested in these streams because they teach us about the formation and structure of the Milky Way and its dark matter halo. Stellar streams give us a snapshot of a larger galaxy being built out of smaller ones,” says Shipp. “These discoveries are possible because DES is the widest, deepest, and best-calibrated survey out there.”

Since there is no universally accepted naming convention for stellar streams, the Dark Energy Survey has reached out to schools in Chile and Australia, asking young students to select names. Students and their teachers have worked together to name the streams after aquatic words in native languages from northern Chile and aboriginal Australia.

Vast halo of hydrogen surrounds Milky Way

The researchers presented the initial findings of the Dark Energy Survey during the American Astronomical Society meeting in Washington, DC on January 10.

Funding came from the US Department of Energy Office of Science and the National Science Foundation.

Source: University of Chicago

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spikey-trio_770

Mass extinctions took out dinosaurs but not diversity

Sixty-five million years ago, clouds of ash choked the skies over Earth. Dinosaurs, along with about half of all the species on Earth, staggered and died.

But in the seas, a colorful population of marine bivalves—the group including oysters, clams, and scallops—soldiered on, tucked into the crevices of ocean floors and shorelines. Though they also lost half their species, curiously, at least one species in each ecological niche survived.

three bivalves on black
Scientists examined how species (including these colorful marine bivalves) are lost in mass extinctions compared to environmental changes between the tropics and the poles. (Credit: Stewart Edie)

University of Chicago scientists document this surprising trend in the Proceedings of the National Academy of Sciences. Though the mass extinction wiped out staggeringly high numbers of species, they barely touched the overall “functional” diversity—how each species makes a living, be it filtering phytoplankton or eating small crustaceans, burrowing or clamping onto rocks.

The same held true for the biggest mass extinction of all, 250 million years ago: more than 90 percent of all species on Earth died out, but no modes of life disappeared.

Today’s biodiversity loss

Strangely, the scientists say, this differs from another kind of biodiversity loss: the loss of species today as you move from the warm tropics to the chillier poles. The number of species drops 80 percent to 95 percent from the tropics to the cold, snowy north and south, and functional variety also declines by 50 percent to 60 percent. Thus losing diversity due to changed environment is entirely possible—all the more reason why it’s strange to see such a pattern of survival in mass extinctions.

“The big question is: Given that we’re working on a mass extinction right now, which flavor will it be?”

“Multicellular life almost didn’t make it out of the Paleozoic era, but every functional group did. Then we see that functional diversity drops way down from tropics to poles; it parallels species loss in a way that’s totally different from the big extinctions. That’s wild—really fascinating and unexpected and strange,” says coauthor David Jablonski, professor of geophysical sciences.

This could have implications for how the mass extinction currently gathering steam could unfold and how badly it will affect Earth ecosystems, the authors say.

Jablonski and graduate student Stewart Edie, who is the first author of the paper, ran the numbers for two major mass extinctions in history: the relatively gradual end-Paleozoic extinction, perhaps driven by changing climates and ocean composition, and later, the sharper end-Cretaceous extinction, thought to be caused by a meteor impact and/or volcanic eruptions. Though they are very different stresses, the same pattern emerged.

“The rug gets pulled out from underneath all the species,” says Edie. “The landscape of the world completely and suddenly changed, making it all the more surprising that all functional types survived. Even the functional groups with only one or two species somehow make it through.”

Delicate balance

The question is pressing because functional diversity is what makes ecosystems tick. Ecosystems are delicately balanced, and losing ecological roles throws a system out of whack: Think of a forest damaged when the deer population explodes because the wolves that prey on them are removed. That balance keeps soil fertile, oceans full of fish, and grass growing for livestock.

Meteor that killed dinos may have sped up bird evolution

“The big question is: Given that we’re working on a mass extinction right now, which flavor will it be?” Jablonski says. “Will we have a tropic-to-poles type, where we lose half our functional groups and so ecosystems are massively altered? Or will it be a mass extinction where you can lose all these species, but the functional groups still somehow manage to limp on? We need to understand this.”

The other author of the paper is James W. Valentine with the University of California, Berkeley. Funding came from the National Science Foundation and NASA.

Source: University of Chicago

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Maps link WWI anxieties to climate’s effect on kelp

In the early 1900s, the US Department of Agriculture recognized a problem. The United States relied heavily on fertilizer to grow crops and support its burgeoning economy, yet a crucial ingredient for fertilizer—potash, a mixture of potassium and salts—came almost exclusively from German mines. German mines supplied nearly the entire world’s supply of potash, and at the time the US used about a fifth of its output, half of the amount Germany exported.

“It is obviously undesirable that the United States should be dependent upon any other nation for its supply of a necessity,” wrote Frank Cameron, an officer “in charge of chemical, physical, and fertilizer investigations” for the USDA, in a 1915 report.

Seeking ways to ease this dependency, the USDA commissioned several surveys of an alternative source of potash: kelp beds in the Pacific Northwest. The large, hardy seaweed is a natural source of potassium, nitrogen, and salts, and had been used as fertilizer for years by Native Americans and settlers. If kelp could be harvested and processed in large enough quantities, it could be a viable source of potash to offset German imports.

So, the USDA sent surveyors—including George Rigg, an ecologist from the University of Washington—to map the kelp beds along the coast of California, Oregon, Washington, and Alaska. Rigg set out in a yacht with a 40-horsepower motor and mapped the coastline around Puget Sound in 1911-12.

More than 100 years later, scientists at the University of Chicago used these maps to track historical changes in the kelp forests of the Pacific Northwest.

As it turned out, the original maps from the kelp surveys ended up at the University of Chicago Library, where Cathy Pfister, professor in the department of ecology and evolution, discovered them. She worked with the library’s preservation staff to digitize the maps, and compared them to modern surveys conducted by the Washington State Department of Natural Resources over the past 26 years.

Resilient kelp

What they found is a relatively rare positive story when it comes to ecological studies in a time of accelerating climate change. The abundance of most modern kelp beds along the Washington coast has remained constant over the last century despite a seawater temperature increase of 0.72 degrees Celsius. The few exceptions are kelp beds closest to Puget Sound, Seattle, and Tacoma.

“Kelp are a robust and resilient structure. You can see that in the data, as long as they have access to good water quality and waves flush through them, then they persist,” Pfister says.

Pfister and her team also studied the competition among kelp species in the area. While the kelp beds were persistent over the decades, their populations could fluctuate greatly from year to year. There are two dominant species—the annual bull kelp and the perennial giant kelp—and they fluctuated similarly, meaning that if one was abundant in a given year, so was the other. And good years, it turns out, are associated with colder seawater temperatures, an unfortunate preference for kelp as ocean temperatures continue to rise.

Spores from healthy kelp travel miles to rescue sick ones

Understanding how changes in the ocean affect kelp is important because they’re what’s called a “foundation species,” a crucial source of food and habitat for organisms.

“Kelp are a natural feature that generates habitat for hundreds, probably thousands of species of fish, invertebrates, and microbes,” Pfister says. “They’re really a locus for biodiversity along these shores, so it’s important to understand how they respond to climate change.”

Gunpowder

While Cameron’s 1915 report delves into the chemistry of potassium salts, nitrogen, and fertilizer, it’s vague on exactly what the US government wanted do with a new kelp-based source of potash.

How the Industrial Age hinged on Pacific bird poo

But given that the world’s supply of potash came from an increasingly belligerent German Empire just before World War I broke out, one could read between the lines and look to another industry that sprung up around the same time in California. These outfits focused on harvesting kelp and extracting chemicals from it, one of which, potassium nitrate or saltpeter, is a major ingredient of gunpowder.

Ultimately, kelp never became a major source of potash for the US agricultural industry. Following the war, harvesting kelp for nitrogen became far more costly than a new commercial process invented by Fritz Haber in Germany to pull nitrogen from the atmosphere. For the benefit of the many species that depend upon them, the kelp beds (and the historic maps) remain.

The study appears in the Journal of Ecology.

Source: University of Chicago

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Why self-folding objects get stuck

Sticking points are simply intrinsic to structures designed to fold themselves, according to new research.

Scientists and engineers are fascinated by self-folding structures. Imagine the possibilities: Heart stents that unfold in the right location or pop-up tents that assemble at the press of a button, as well as nanoscale versions for tiny machines. But sometimes these structures get stuck during the folding process, and scientists don’t know why.

“No matter how clever the design, there are always many more ways to fold incorrectly and get stuck than to fold correctly…”

“People thought you could engineer around it, but it really looks like there are fundamental limits,” says University of Chicago graduate student Menachem Stern, the first author of the paper.

Structures designed to self-assemble often start out correctly, but then the folding peters out, leaving behind islands of properly folded parts. To explore why, the team created a set of mathematical models.

When designing structures that can fold themselves, whether paper origami or tiny nanomachines, scientists start by pre-creasing the folds they need. But this also creates a set of invisible “distractor” branches. The more pre-creases they add, the more distractor branches form, and the origami is more and more likely to get stuck.

“No matter how clever the design, there are always many more ways to fold incorrectly and get stuck than to fold correctly,” says Arvind Murugan, assistant professor in the James Franck Institute and coauthor of the paper.

“We realized that this problem of having many more ways to do something incorrectly than correctly shows up in many other areas of science and mathematics, including the design of protein structures in biology and the design of Sudoku puzzles.”

Using these connections, there are ways to mitigate the problem even if it is intrinsic, say Stern, Murugan, and Matthew Pinson, the study’s third author.

Lego and Play-Doh inspire particles that self-assemble

Their findings include a set of predictions for where to place hinges when designing folds, as well as for identifying problem areas and how to fix them—which could apply to everything from paper origami to micro-machines to self-assembling tents.

The researchers report their new findings in the journal Physical Review X.

Funding came from the University of Chicago Materials Research Science and Engineering Center, National Science Foundation.

Source: University of Chicago

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Poor health more likely for babies born near fracking

Babies born to mothers living up to about 2 miles from a hydraulic fracturing site suffer from poorer health, new research indicates.

The largest impacts were to babies born within about a half mile of a site, with those babies being 25 percent more likely to be born at a low birth weight—leaving them with a greater risk of infant mortality, ADHD, asthma, lower test scores, lower schooling attainment, and lower earnings.

The risk of giving birth to an infant with a low birth weight decreases the farther the mother lives from a site, the study finds.

From North Dakota to Texas to Pennsylvania, hydraulic fracturing has transformed many places in America into energy powerhouses. But while some see the new energy boom as benefiting the local economy, others fear the potential health and environmental consequences.

“Broadly, hydraulic fracturing has reduced energy prices and caused natural gas to greatly decrease the use of coal for power generation in the United States, leading to reductions in air pollution that have very likely improved health throughout the country,” says study coauthor Michael Greenstone, professor in economics and director of the Energy Policy Institute at the University of Chicago.

“But these national benefits depend on local communities allowing hydraulic fracturing and governments around the world have taken very different approaches with some banning it and others embracing. This study provides the first large-scale peer-reviewed evidence of a link between hydraulic fracturing activities and our health, specifically the health of babies,” he says. The findings appear in Science Advances.

The risk of giving birth to an infant with a low birth weight decreases the farther the mother lives from a site, the study finds. Infants born to mothers living about a half to 2 miles from a site also experienced increases in the probability of low birth weight but the effect is smaller—about a half to a third of the effect within about a half mile.

In contrast, the study found no evidence of impacts on infant health among babies born to mothers living farther than about 2 miles from a fracking site. These results suggest that hydraulic fracturing does have an impact on infant health, but only at a highly localized level. Out of the nearly 4 million babies born in the United States each year, about 29,000 of them are born within about a half mile of a fracking site, while another 95,500 are born about a half to 2 miles away.

“While we know proximity to hydraulic fracturing sites is associated with compromised infant health, we do not yet know the mechanism—air or water pollution, chemicals onsite, an increase in traffic, or some other channel—or whether it affects health after birth,” says coauthor Katherine Meckel, an assistant professor at the University of California, Los Angeles.

These fracking sites are close to drinking water wells

“This is a critical area for future research because it can help identify ways to mitigate or even erase the health effects, without causing communities to lose out on the local economic benefits of hydraulic fracturing,” Meckel says.

Meckel, Greenstone, and their coauthor Janet Currie, professor of economics and public affairs at Princeton University and the director of the university’s Center for Health and Wellbeing, discovered their findings by comparing infants born to mothers living near a drilling site to those living farther from a site both before and after the drilling began.

As a check, the study further refines this comparison so that it is based on siblings who were exposed to fracking with those who were not. The study relies on birth certificate data from more than 1.1 million births in Pennsylvania from 2004 to 2013.

This study of the impacts of hydraulic fracturing on infant health follows a study by Greenstone, Currie, and other colleagues on its local economic benefits. That study, released last December, found the average household living near a hydraulic fracturing site benefits by about $1,900 per year. This is driven by a 7 percent increase in average income due to rises in wages and royalty payments, a 10 percent increase in employment, and a 6 percent increase in housing prices.

Home values can sink or swim near fracking

The authors caution, however, that new information on the local health consequences of hydraulic fracturing is likely to influence housing prices if it differs from current expectations of health effects.

“Housing prices are not fixed, they are based on many factors including how well the job market is and how safe the area is to live in,” says Currie. “As these results, and others on the health impacts from hydraulic fracturing, become mainstreamed into the consciousness of homeowners and home buyers, the local economic benefits could change.”

Source: University of Chicago

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Our solar system may have formed in a star-making ‘bubble’

Scientists have proposed a new, comprehensive theory for how our solar system could have formed in the wind-blown bubbles around a giant, long-dead star.

The study addresses a nagging cosmic mystery about the abundance of two elements in our solar system compared to the rest of the galaxy.

The general prevailing theory is that our solar system formed billions of years ago near a supernova. But the new scenario instead begins with a giant type of star called a Wolf-Rayet star, which is more than 40 to 50 times the size of our own sun. They burn the hottest of all stars, producing tons of elements which are flung off the surface in an intense stellar wind. As the Wolf-Rayet star sheds its mass, the stellar wind plows through the material that was around it, forming a bubble structure with a dense shell.

A simulation shows how stellar winds carry mass from a giant star over the course of millions of years, forming bubbles around it—which could have served as the origins of our solar system. Simulation by V. Dwarkadas/D. Rosenberg. via GIPHY

“The shell of such a bubble is a good place to produce stars,” because dust and gas become trapped inside where they can condense into stars, says coauthor Nicolas Dauphas, professor in the geophysical sciences department at the University of Chicago. The authors estimate that 1 percent to 16 percent of all sun-like stars could be formed in such stellar nurseries.

This setup differs from the supernova hypothesis in order to make sense of two isotopes that occur in strange proportions in the early solar system, compared to the rest of the galaxy. Meteorites left over from the early solar system tell us there was a lot of aluminium-26. In addition, studies, including a 2015 one by Dauphas and a former student, increasingly suggest we had less of the isotope iron-60.

This brings scientists up short, because supernovae produce both isotopes. “It begs the question of why one was injected into the solar system and the other was not,” says coauthor Vikram Dwarkadas, a research associate professor in astronomy and astrophysics.

This brought them to Wolf-Rayet stars, which release lots of aluminium-26, but no iron-60.

bubble simulation (solar system origins)
A still shot of the simulation showing how bubbles form over the course of 4.7 million years from the intense stellar winds off a massive star. (Credit: U. Chicago)

“The idea is that aluminum-26 flung from the Wolf-Rayet star is carried outwards on grains of dust formed around the star. These grains have enough momentum to punch through one side of the shell, where they are mostly destroyed—trapping the aluminum inside the shell,” Dwarkadas says. Eventually, part of the shell collapses inward due to gravity, forming our solar system.

As for the fate of the giant Wolf-Rayet star that sheltered us: Its life ended long ago, likely in a supernova explosion or a direct collapse to a black hole. A direct collapse to a black hole would produce little iron-60; if it was a supernova, the iron-60 created in the explosion may not have penetrated the bubble walls, or was distributed unequally.

This star is like ‘time travel’ to our early solar system

The scientists lay out their theory in the Astrophysical Journal.

Other authors of the paper include undergraduate student Peter Boyajian of University of Chicago and Michael Bojazi and Brad Meyer of Clemson University. Funding for the research came from NASA.

Source: University of Chicago

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Can middle-class support ease Medicaid’s stigma?

Medicaid is now seen as an important part of the middle-class social safety net, thanks to nearly 60 percent of Americans being connected to the program directly or through a family member or close friend, a new study indicates.

Earlier this year, a concerted effort by Republicans in Congress to repeal and replace the Affordable Care Act hit a surprising road block: strong pushback against cuts to Medicaid. How did a program once tied to a “welfare stigma” become so fiercely debated, transcending partisan divides?

More than 90 percent of Americans say they would sign up for Medicaid if they were eligible.

In their new study, researchers found that those with a connection to Medicaid were more likely to view the program as important and to support increases in spending than those with no connection. Medicaid provides health care coverage to nearly 68 million low income and elderly Americans.

While most means-tested programs in the United States, like food stamps and public housing, are stigmatizing, Medicaid has proven resilient to retrenchment and has actually expanded dramatically over the years, most recently through the Affordable Care Act.

The question is: Has it become something closer to a non-partisan, middle-class entitlement program?

“These findings suggest that, although partisanship is important, Medicaid constituents and their allies are primed to be mobilized to not only protect the program against retrenchment but also to proactively fight for expansion,” says Colleen M. Grogan, a professor in the School of Social Service Administration at the University of Chicago.

“If Medicaid constituents can be sufficiently mobilized, then Medicaid can begin to mimic the politics of a middle-class entitlement,” she adds.

Book: Status quo trumps evidence in U.S. health care

Researchers used the Kaiser Family Foundation Poll: Medicare and Medicaid at 50, a nationally representative survey of 1,849 participants. Using the data, Grogan and Park examined three questions: Are individuals with a connection to Medicaid more likely to view the program as important? Are they more likely to support an increase in Medicaid spending? Are they more likely to support adoption of the Medicaid expansion under the Affordable Care Act?

The researchers found that more than half of all Americans are connected to the Medicaid program either directly or indirectly, and are significantly more likely to view the program as important and support increases to it. Further, more than 90 percent of Americans say they would sign up for the program if eligible.

For future research, Grogan and Park recommend exploring whether people with different types of connections to Medicaid view the program differently and, if so, how and why—and whether state-level attempts to destigmatize the program by renaming it would also reduce knowledge of and support for the program.

Poll finds most and least popular parts of ACA

The researchers report their findings in The Millbank Quarterly.

Source: University of Chicago

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