In a new study, physicists led by the University of Iowa report a new feature to Earth’s atmospheric light show. Examining video taken nearly two decades ago, the researchers describe multiple instances where a section of the diffuse aurora — the faint, background-like glow accompanying the more vivid light commonly associated with auroras — goes dark, as if scrubbed by a giant blotter. Then, after a short period of time, the blacked-out section suddenly reappears.

The researchers say the behavior, which they call “diffuse auroral erasers,” has never been mentioned in the scientific literature. The findings appear in the Journal of Geophysical Research Space Physics.

Auroras occur when charged particles flowing from the sun — called the solar wind — interact with Earth’s protective magnetic bubble. Some of those particles escape and fall toward our planet, and the energy released during their collisions with gases in Earth’s atmosphere generate the light associated with auroras.

“The biggest thing about these erasers that we didn’t know before but know now is that they exist,” says Allison Jaynes, assistant professor in the Department of Physics and Astronomy at Iowa and study co-author. “It raises the question: Are these a common phenomenon that has been overlooked, or are they rare?

“Knowing they exist means there is a process that is creating them,” Jaynes continues, “and it may be a process that we haven’t started to look at yet because we never knew they were happening until now.”

It was on March 15, 2002, that David Knudsen, a physicist at the University of Calgary, set up a video camera in Churchill, a town along Hudson Bay in Canada, to film auroras. Knudsen’s group was a little disheartened; the forecast called for clear, dark skies — normally perfect conditions for viewing auroras — but no dazzling illumination was happening. Still, the team was using a camera specially designed to capture low-level light, much like night-vision goggles.

Though the scientists saw only mostly darkness as they gazed upward with their own eyes, the camera was picking up all sorts of auroral activity, including an unusual sequence where areas of the diffuse aurora disappeared, then came back.

Knudsen, looking at the video as it was being recorded, scribbled in his notebook, “pulsating ‘black out’ diffuse glow, which then fills in over several seconds.”

“What surprised me, and what made me write it in the notebook, is when a patch brightened and turned off, the background diffuse aurora was erased. It went away,” says Knudsen, a Fort Dodge, Iowa, native who has studied aurora for more than 35 years and is a co-author on the study. “There was a hole in the diffuse aurora. And then that hole would fill back in after a half-minute or so. I had never seen something like that before.”

The note lay dormant, and the video unstudied, until Iowa’s Jaynes handed it to graduate student Riley Troyer to investigate. Jaynes learned about Knudsen’s recording at a scientific meeting in 2010 and referenced the eraser note in her doctoral thesis on diffuse aurora a few years later. Now on the faculty at Iowa, she wanted to learn more about the phenomenon.

“I knew there was something there. I knew it was different and unique,” says Jaynes, assistant professor in the Department of Physics and Astronomy. “l had some ideas how it could be analyzed, but I hadn’t done that yet. I handed it to Riley, and he went much further with it by figuring out his own way to analyze the data and produce some significant conclusions.”

Troyer, from Fairbanks, Alaska, took up the assignment with gusto.

“I’ve seen hundreds of auroras growing up,” says Troyer, who is in his third year of doctoral studies at Iowa. “They’re part of my heritage, something I can study while keeping ties to where I’m from.”

Troyer created a software program to key in on frames in the video when the faint erasers were visible. In all, he cataloged 22 eraser events in the two-hour recording.

“The most valuable thing we found is showing the time that it takes for the aurora to go from an eraser event (when the diffuse aurora is blotted out) to be filled or colored again,” says Troyer, who is the paper’s corresponding author, “and how long it takes to go from that erased state back to being diffuse aurora. Having a value on that will help with future modeling of magnetic fields.”

Jaynes says learning about diffuse auroral erasers is akin to studying DNA to understand the entire human body.

“Particles that fall into our atmosphere from space can affect our atmospheric layers and our climate,” Jaynes says. “While particles with diffuse aurora may not be the main cause, they are smaller building blocks that can help us understand the aurora system as a whole, and may broaden our understanding how auroras happen on other planets in our solar system.”

Video: https://www.youtube.com/watch?v=7furDMNIil0&t=1s

But growing demand for data, and the means to store them, is driving scientists to search beyond silicon for materials that can push memory devices to higher densities, speeds, and security.

Now MIT physicists have shown preliminary evidence that data might be stored as faster, denser, and more secure bits made from antiferromagnets.

Antiferromagnetic, or AFM materials are the lesser-known cousins to ferromagnets, or conventional magnetic materials. Where the electrons in ferromagnets spin in synchrony — a property that allows a compass needle to point north, collectively following the Earth’s magnetic field — electrons in an antiferromagnet prefer the opposite spin to their neighbor, in an “antialignment” that effectively quenches magnetization even at the smallest scales.

The absence of net magnetization in an antiferromagnet makes it impervious to any external magnetic field. If they were made into memory devices, antiferromagnetic bits could protect any encoded data from being magnetically erased. They could also be made into smaller transistors and packed in greater numbers per chip than traditional silicon.

Now the MIT team has found that by doping extra electrons into an antiferromagnetic material, they can turn its collective antialigned arrangement on and off, in a controllable way. They found this magnetic transition is reversible, and sufficiently sharp, similar to switching a transistor’s state from 0 to 1. The results, published today in Physical Review Letters, demonstrate a potential new pathway to use antiferromagnets as a digital switch.

“An AFM memory could enable scaling up the data storage capacity of current devices — same volume, but more data,” says the study’s lead author Riccardo Comin, assistant professor of physics at MIT.

Comin’s MIT co-authors include lead author and graduate student Jiarui Li, along with Zhihai Zhu, Grace Zhang, and Da Zhou; as well as Roberg Green of the University of Saskatchewan; Zhen Zhang, Yifei Sun, and Shriram Ramanathan of Purdue University; Ronny Sutarto and Feizhou He of Canadian Light Source; and Jerzy Sadowski at Brookhaven National Laboratory.

Magnetic memory

To improve data storage, some researchers are looking to MRAM, or magnetoresistive RAM, a type of memory system that stores data as bits made from conventional magnetic materials. In principle, an MRAM device would be patterned with billions of magnetic bits. To encode data, the direction of a local magnetic domain within the device is flipped, similar to switching a transistor from 0 to 1.

MRAM systems could potentially read and write data faster than silicon-based devices and could run with less power. But they could also be vulnerable to external magnetic fields.

“The system as a whole follows a magnetic field like a sunflower follows the sun, which is why, if you take a magnetic data storage device and put it in a moderate magnetic field, information is completely erased,” Comin says.

Antiferromagnets, in contrast, are unaffected by external fields and could therefore be a more secure alternative to MRAM designs. An essential step toward encodable AFM bits is the ability to switch antiferromagnetism on and off. Researchers have found various ways to accomplish this, mostly by using electric current to switch a material from its orderly antialignment, to a random disorder of spins.

“With these approaches, switching is very fast,” says Li. “But the downside is, everytime you need a current to read or write, that requires a lot of energy per operation. When things get very small, the energy and heat generated by running currents are significant.”

Doped disorder

Comin and his colleagues wondered whether they could achieve antiferromagnetic switching in a more efficient manner. In their new study, they work with neodymium nickelate, an antiferromagnetic oxide grown in the Ramanathan lab. This material exhibits nanodomains that consist of nickel atoms with an opposite spin to that of its neighbor, and held together by oxygen and neodymium atoms. The researchers had previously mapped the material’s fractal properties.

Since then, the researchers have looked to see if they could manipulate the material’s antiferromagnetism via doping — a process that intentionally introduces impurities in a material to alter its electronic properties. In their case, the researchers doped neodymium nickel oxide by stripping the material of its oxygen atoms.

When an oxygen atom is removed, it leaves behind two electrons, which are redistributed among the other nickel and oxygen atoms. The researchers wondered whether stripping away many oxygen atoms would result in a domino effect of disorder that would switch off the material’s orderly antialignment.

To test their theory, they grew 100-nanometer-thin films of neodymium nickel oxide and placed them in an oxygen-starved chamber, then heated the samples to temperatures of 400 degrees Celsius to encourage oxygen to escape from the films and into the chamber’s atmosphere.

As they removed progressively more oxygen, they studied the films using advanced magnetic X-ray crystallography techniques to determine whether the material’s magnetic structure was intact, implying that its atomic spins remained in their orderly antialignment, and therefore retained antiferomagnetism. If their data showed a lack of an ordered magnetic structure, it would be evidence that the material’s antiferromagnetism had switched off, due to sufficient doping.

Through their experiments, the researchers were able to switch off the material’s antiferromagnetism at a certain critical doping threshold. They could also restore antiferromagnetism by adding oxygen back into the material.

Now that the team has shown doping effectively switches AFM on and off, scientists might use more practical ways to dope similar materials. For instance, silicon-based transistors are switched using voltage-activated “gates,” where a small voltage is applied to a bit to alter its electrical conductivity. Comin says that antiferromagnetic bits could also be switched using suitable voltage gates, which would require less energy than other antiferromagnetic switching techniques.

“This could present an opportunity to develop a magnetic memory storage device that works similarly to silicon-based chips, with the added benefit that you can store information in AFM domains that are very robust and can be packed at high densities,” Comin says. “That’s key to addressing the challenges of a data-driven world.”

In fact, new research shows that stepchildren are not at a disadvantage compared to their peers from single-parent households and actually experience better outcomes than their halfsiblings — good news for the more than 113 million Americans that are part of a steprelationship.

Led by East Carolina University anthropologist Ryan Schacht and researchers from the University of Utah, the study, “Was Cinderella just a fairy tale? Survival differences between stepchildren and their half-siblings,” is available in the May edition of the Philosophical Transactions of the Royal Society B.

The study challenges the “Cinderella effect” theory. The effect contends that conflict within stepfamilies over physical, financial and emotional resources leads to higher mortality risks for stepchildren, and is a main factor in higher rates of abuse and neglect. The phenomenon suggests that stepparents play a major role in this abuse, hoarding resources for their biological children and leading to negative outcomes for stepchildren.

Schacht proposes that previous studies have placed blame for the negative outcomes associated with parental loss on stepparents yet have done so through an an “apples-to-oranges comparison.” Specifically, they compare of the long-term outcomes of children who have suffered trauma like parental loss versus children from stable households. When the team compared stepchild outcomes more appropriately among those children who too have experienced the economic and emotional hardships associated with parental loss, they found no difference. Specifically, the introduction stepparenents did not increase stepchild mortality.

“The idea of a stepparent, especially the stepmother, as being an agent of evil seems to be a story as old as time,” Schacht said. “It’s easy to sell the Cinderella effect’s result because we’ve been told these stories about the problems that stepfamilies experience for hundreds of years.

“We’re not denying that some stepchildren suffer,” he said. “However, if we truly believe it is the stepparent that is the source of negative outcomes for a stepchild, then we need to compare similar environments and experiences. A child that hasn’t lost a parent through death or divorce hasn’t experienced the same trauma that a stepchild has; comparing those two experiences and blaming the stepparent for diverging outcomes isn’t a fair comparison.”

The study compared the mortality of stepchildren whose parents remarried after the death of a spouse to children whose parents did not remarry and found three key findings:

* Parental mortality has a negative effect on children under 18 years old, especially for infants losing a mother;

* Children whose parents remarried after the loss of a spouse did not suffer a mortality rate any greater than children whose parents did not remarry; and

* Stepchildren received a protective effect when a halfsibling was introduced to their new family.

“The metrics of what makes a family successful — household stability, relationship stability and economic stability — are achieved by stepparents investing in their stepchildren to make that a reality. Coming in with an antagonistic approach doesn’t make sense if stepparents want their relationship to succeed.”

The research team analyzed a data set of more than 400,000 children from Utah from 1847-1940. Schacht said the time period provided an opportunity to analyze stepchild mortality rates in families during a natural fertility period where families were larger in size and most stepfamilies were formed due to the death of a parent.

The study adds that children who have suffered parental loss have more in common with their peers from single-parent households, facing many of the same educational, economic and health care disparities.

Schacht hopes the study will shed a light on public policy funding for interventions for families that have suffered parental loss.

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Materials provided by East Carolina University. Original written by Matt Smith. Note: Content may be edited for style and length.

Now University of Alabama at Birmingham researchers have moved a step closer to possible clinical testing of this treatment, say Elson and co-first authors Katie Alexander, Ph.D., and Qing Zhao, M.D., Ph.D. Their study, published in the journal Gastroenterology, is the first to describe IgG antibodies in Crohn’s disease specific for human-derived flagellins of bacteria belonging to the Lachnospiraceae family. Knowledge of the specific flagellin epitopes that drive the pathogenic adaptive immune response in Crohn’s disease is necessary information for Elson’s potential triple-punch Crohn’s disease treatment. Goals of the treatment are removing or exhausting pathogenic T memory cells and increasing the number of immunomodulatory T regulatory cells.

Elson is a professor, Alexander an assistant professor and Zhao a postdoctoral fellow in the UAB Department of Medicine Division of Gastroenterology and Hepatology.

Crohn’s disease and ulcerative colitis — another type of inflammatory bowel disease — are characterized by dysregulated adaptive immune responses to the microbiota in genetically susceptible individuals, but the human specificity of these responses had so far been largely undefined. Mouse microbiota flagellins have previously been defined as immunodominant antigens in Crohn’s disease.

Flagellins are building blocks of the hairlike motility flagella that extend from the bacterial cell wall. Flagellin is a potent immune activator and antigen, and it is the only known microbial protein that has three receptors for innate immunity encoded in the host genome, in addition to immunoglobulin and T cell receptors.

The UAB researchers individually probed blood sera from 87 healthy volunteers, 152 patients with Crohn’s disease and 170 patients with ulcerative colitis. They used protein arrays of microbiota bacterial flagellins of both mouse and human origin, and they analyzed sera for IgG and IgA antibody responses.

They found selective patterns of antibody reactivity to microbiota flagellins among the inflammatory bowel disease patients.

The Crohn’s disease patients — but not the ulcerative colitis patients — had augmented serum IgG antibodies to Lachnospiraceae flagellins from various species of Roseburia and one species of Eubacterium. These bacteria are normal residents in the human ileum, the third segment of the small intestine. A subset of the Crohn’s disease patients had very high responses, with antibodies against more than 10 different flagellins.

For that subset of Crohn’s disease patients, the multiflagellin hyper-reactivity was associated with indications of severe dysregulated immune response. Patients in the subset had: 1) elevated flagellin-specific T memory cells; 2) a reduced ratio of flagellin-reactive T regulatory to T effector cells; and 3) a high frequency of disease complications.

“Thus,” Elson said, “Crohn’s disease patients displayed a strong adaptive immune response to human-derived Lachnospiraceae flagellins, which may be targeted for prognosis and future personalized therapies.”

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Materials provided by University of Alabama at Birmingham. Original written by Jeff Hansen. Note: Content may be edited for style and length.