Human sewage can introduce disease-causing pathogens and nitrogen into the ocean, potentially impacting human health as well as coastal ecosystems and the communities that depend on them for such purposes as fishing. However, most research into humans’ impact on coastal ecosystems has focused on agricultural runoff, while investigations on human sewage have been limited.

To better capture the impact of sewage on coastal ecosystems, Tuholske and colleagues conducted a novel analysis in which they estimated and mapped nitrogen and pathogen inputs into the ocean from sewage for about 135,000 watersheds around the world at a resolution of 1 kilometer. The assessment employed newly available, high-resolution data on global human populations and modeled how wastewater plumes entering the ocean would overlap with different ecosystems.

The analysis suggests that wastewater from human sewage introduces 6.2 teragrams of nitrogen into coastal ecosystems per year — for comparison, that is about 40 percent of estimated inputs from agriculture. Sixty-three percent of the nitrogen is from sewage systems, 5 percent from septic systems, and 32 percent from untreated, direct input.

Of the watersheds that appear to release the most nitrogen from sewage, most are located in India, Korea, and China, with the Chang Jiang (Yangtze) River contributing 11 percent of the global total. The researchers also identified hotspots for coral reef exposure to nitrogen in China, Kenya, Haiti, India, and Yemen. Seagrass exposure hotspots were found in Ghana, Kuwait, India, Nigeria, and China. The Chang Jiang and Brahmaputra Rivers have the highest input of pathogens.

Further research will be needed to refine the model and its estimates. Nonetheless, this work provides a new resource that could play a key role in efforts to mitigate harm to ecosystems and human health — such as by highlighting locations where tradeoffs between managing nitrogen and pathogen levels are particularly important to consider.

The authors add: “The sheer scale of how much wastewater is impacting coastal ecosystems worldwide is staggering. But because we map wastewater inputs to the ocean across more than 130,000 watersheds, our results identify target priority areas to help marine conservation groups and public health officials to work together and reduce the impacts of wastewater on coastal waters across the planet.”

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The researchers have created a visual representation of their research, available at: http://www.globalwastewatermodel.com/webmap.html

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Materials provided by PLOS. Note: Content may be edited for style and length.

About 64,000 people in the U.S. are diagnosed with type 1 diabetes each year, according to the Juvenile Diabetes Research Foundation. There is no cure for the disease, and to manage symptoms, people must measure their blood sugar levels throughout the day and administer insulin through an injection or pump. Although scientists still don’t know exactly what causes the body to turn against itself and attack insulin-secreting cells, people with type 1 diabetes have fewer regulatory T cells (Tregs) — immune cells that suppress the differentiation and activation of other, self-attacking T cells. In a recent study published in ACS’ Nano Letters, Yunfeng Lin and colleagues showed that treating mice with tFNAs could prevent type 1 diabetes, in part by increasing Treg numbers. Originally designed to carry other therapeutic molecules into cells, tFNAs have recently been shown to modulate the immune system on their own. Now, the researchers wanted to find out if these molecules could reverse new-onset type 1 diabetes, before pancreatic β-cells were completely destroyed.

The researchers made tFNAs from four single-stranded DNA segments that self-assembled into pyramid-like shapes, called tetrahedrons. But whereas a pyramid is square at its base, tetrahedrons are triangular. Then, every other day for 4 weeks, they injected the tFNAs into 10 mice with new-onset type 1 diabetes, while 10 other diabetic mice were injected with saline. In the control mice, blood glucose levels continued to rise, and 60% of the mice died during the 12-week follow-up period. In contrast, blood glucose levels in mice treated with tFNAs went down to normal levels, and none of the rodents died. In a further analysis of the tFNA-treated mice, the team found that pancreatic β-cells were protected, and Tregs were restored to normal levels, while auto-reactive T cells decreased in the pancreas. Although the findings still need to be verified in people, tFNAs are one of the most promising candidates for type 1 diabetes immunotherapy, the researchers say.

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So he turned it over to his research student, Rajan Itani, who is pursuing a doctorate in physics at the University of Alaska Fairbanks.

The result: a paper authored by Itani, coauthored by Conde, and featured as an editor’s highlight recently in the American Geophysical Union magazine Eos. The magazine notes that fewer than 2% of papers receive such attention.

The paper itself was published in September in the Journal of Geophysical Research: Space Physics.

“I am delighted that our paper has been featured as an editor’s highlight in Eos,” Itani said. “It is a proud moment in my career in space physics, as it marks my first paper being promoted. I am thankful to my adviser, Dr. Mark Conde, for suggesting the research topic and for his endless support and encouragement.”

Itani confirmed that the cross-polar jet, a well-known wind in the upper atmosphere, sometimes inexplicably stops or is deflected or reversed when it reaches the region above Alaska.

The finding upends previous understanding.

Itani’s research at the UAF Geophysical Institute, with assistance from Conde and conducted mostly with data from the university’s Poker Flat Research Range, focused only on the Alaska region. But it is likely that the cross-polar jet would also stall elsewhere on the globe at high latitudes as the wind emerges from the polar cap around midnight.

Conde and Itani were studying the upper thermosphere, the region of atmosphere above 90 miles altitude.

This cross-polar jet carries the thin air in this region over the North Pole from the Earth’s dayside to its nightside and delivers it toward the equator, where it dissipates. Sometimes, according to Itani’s research, the forces driving the wind aren’t strong enough to push it through the background atmosphere on the Earth’s night side.

“This cross-polar jet is a major, large-scale persistent feature of the upper atmospheric circulation,” said Conde, who is a professor in the UAF Department of Physics. “And stopping it like that means that the trajectories of particles carried by the wind would change dramatically.”

“All of the computer models say that this wind spills out quite some distance toward the equator and then eventually slows and blends into the background flow, just like traffic merging onto a highway,” Conde said. “There should be quite a strong flow extending far equatorward, but we find that it basically just hits a wall over Alaska on some occasions. It really should continue and spill out just like the models say.”

The finding has implications for spacecraft orbits, space debris avoidance, ionospheric storm modeling and our understanding about the transport of air in the thermosphere.

The thermosphere is far less dense, almost to a vacuum, compared to air at the Earth’s surface. And that means the occasional stalling of the cross-polar jet won’t be noticed on the surface or affect life here.

But what causes this stalling? That hasn’t been resolved yet. Itani’s paper does offer a correlation, however: A review of seven years of data shows a “strong influence” from solar activity. Thermospheric wind stalling is most likely to occur during solar minimum, the period of low disturbance on the sun’s surface.

Conde had actually seen the wind stalling in data at various times since the late 1990s when he began studying the impact of auroral displays on thermospheric winds above Alaska.

“I was never completely sure whether what I was seeing in the data truly reflected what the atmosphere was really doing or whether it was just some weird instrumental thing,” he said. “For a long time, I couldn’t really check, because there was no other technique that could do it.

“But over the years as we’ve run multiple instruments and combined the data from those many instruments, I eventually just came to understand that what we were seeing was a real phenomenon,” he said.

Conde published a paper in 2018 that noted the thermospheric wind stalling; however, Itani’s paper expands on that work in more detail.

“Training the next generation of scientists is a major objective of the United States’ premier research institution, the National Science Foundation, which funded the work,” Conde said. “As a result, quite a bit of leading-edge research is done by graduate students. I am very pleased to see Rajan’s work in this area recognized by the American Geophysical Union.”

And doors are kryptonite to robots, said Ou Ma, an aerospace engineering professor at the University of Cincinnati.

“Robots can do many things, but if you want one to open a door by itself and go through the doorway, that’s a tremendous challenge,” Ma said.

Students in UC’s Intelligent Robotics and Autonomous Systems Laboratory have solved this complex problem in three-dimensional digital simulations. Now they’re building an autonomous robot that not only can open its own doors but also can find the nearest electric wall outlet to recharge without human assistance.

This simple advance in independence represents a huge leap forward for helper robots that vacuum and disinfect office buildings, airports and hospitals. Helper robots are part of a $27 billion robotics industry, which includes manufacturing and automation.

The study was published in the journal IEEE Access.

UC College of Engineering and Applied Science doctoral student Yufeng Sun, the study’s lead author, said some researchers have addressed the problem by scanning an entire room to create a 3D digital model so the robot can locate a door. But that is a time-consuming custom solution that works only for the particular room that is scanned.

Sun said developing an autonomous robot to open a door for itself poses several challenges.

Doors come in different colors and sizes with different handles that might be slightly higher or lower. Robots have to know how much force to use to open doors to overcome resistance. Most public doors are self-closing, which means if the robot loses its grip, it has to start over.

Since UC students are using machine learning, the robot has to “teach” itself how to open a door, essentially through trial and error. This can be time-consuming initially, but the robot corrects its mistakes as it goes. Simulations help the robot prepare for the actual task, Sun said.

“The robot needs sufficient data or ‘experiences’ to help train it,” Sun said. “This is a big challenge for other robotic applications using AI-based approaches for accomplishing real-world tasks.”

Now, Sun and UC master’s student Sam King are converting Sun’s successful simulation study into a real robot.

“The challenge is how to transfer this learned control policy from simulation to reality, often referred to as a ‘Sim2Real’ problem,” Sun said.

Digital simulations typically are only 60% to 70% successful in initial real-world applications, Sun said. He expects to spend a year or more bridging the gap to perfect his new autonomous robotics system.

So there’s plenty of time to invest in robot-proof door locks.

Video of a robot that can open a door: https://www.youtube.com/watch?v=O_FV47hIRus

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Materials provided by University of Cincinnati. Original written by Michael Miller. Note: Content may be edited for style and length.