The ice-cliff research was spurred by a helicopter ride over Jakobshavn and Helheim glaciers on Greenland’s eastern coast. Helheim ends abruptly in the ocean, in near-vertical ice-cliffs reaching 30-stories high (100 meters). On the flight, scientists viewed large cracks (called crevasses) on top of the ice that marched towards the end of the glacier.

“Geologists have spent decades — centuries — worrying about slumps,” says Richard Alley, co-author of the new paper in Geology. A slump occurs when mass of rock or sediment loses some of its strength, breaks away from its neighboring land, and slides down a slope. Typically, slumps are marked by a steep scarp where the material broke away, followed by a block of material moved downslope.

Alley says the research team noted that features on Helheim glacier are typical of what you might see in a slump-prone terrestrial landscape and they wondered if ice might suffer the same fate. “You’ve got a crevasse that serves as a head scarp and then you’ve got the stresses [within the ice] maximized down at the water level,” he says.

To test if slumping occurs on ice cliffs, the team monitored Helheim glacier during a calving event, using real-aperture terrestrial radar interferometery. They measured speed, position, and motion of the calving ice. The researchers observed an ice-flow acceleration just before an initial slump, followed by a rotating, full ice-thickness calving of the glacier — including the entire remaining ice-cliff, reaching both above and below the water line.

Removing the weight of the upper ice by slumping encourages the underlying ice to pop upward. “Because it’s still attached at the back, it’s going to rotate a little bit,” says Alley. The rotation causes a crack to form at the bottom of the glacier as the ice flexes. In turn, the crack can weaken the ice, creating a large calving event — all triggered by the initial slump on top of the ice cliff.

After observing the slump-triggered calving event, the team modeled when slumping events were most likely to occur on an ice cliff. The modeling looked at tensile, shear, and compressive failure for ice cliffs, and included characteristics of the ice. The scientists found that cliffs reaching more than 100 meters of ice above water were likely to have slumping occur.

Alley says regular calving events happen relatively slowly, such as when the ice front melts over time, undercutting the ice and weakening the cliff. “But that’s not going to go really, really, really fast because you have to wait for the melting to undercut it,” he says.

With slumping, the calving occurs without waiting for the melt. “We’ll go slump… basal crevasse… boom,” he says, noting that when the calving happens it will take the 100 meters of ice above the water — and the 900 meters below the water — very quickly.

And 1000 meters of ice calving at once isn’t the limit. Alley says that in some places in Antarctica, the glacial ice bed can be 1500 to 2000 meters below sea level, creating a much taller cliff above water. He says the worry is that taller cliffs are even more susceptible to slumping. “The scary thing is that if pieces of west Antarctica start doing what Helheim is doing then over the next hundred years models indicate that we get rapid sea level rise at rates that surpass those predicted,” says Alley.

Understanding the slump-break process has been a collaborative effort, Alley says, and more investigations are planned for the near future. “We want to understand what are the rules for [ice] breakage by this process and others,” says Alley, adding that they hope to collect more observational data as well as refine their models to better understand the slump-break process. “There’s still work to be done.”

The research was supported by NASA, the National Science Foundation, and the New York University Abu Dhabi Research Institute.

The new sensor, whose readings can be monitored on an easy-to-use graphic display called a NILM (non-intrusive load monitoring) dashboard, is described in the March issue of IEEE Transactions on Industrial Informatics, in a paper by MIT professor of electrical engineering Steven Leeb, recent graduate Andre Aboulian MS ’18, and seven others at MIT, the U.S. Coast Guard, and the U.S. Naval Academy. A second paper will appear in the April issue of Marine Technology, the publication of the Society of Naval Architects and Marine Engineers.

The system uses a sensor that simply is attached to the outside of an electrical wire at a single point, without requiring any cutting or splicing of wires. From that single point, it can sense the flow of current in the adjacent wire, and detect the distinctive “signatures” of each motor, pump, or piece of equipment in the circuit by analyzing tiny, unique fluctuations in the voltage and current whenever a device switches on or off. The system can also be used to monitor energy usage, to identify possible efficiency improvements and determine when and where devices are in use or sitting idle.

The technology is especially well-suited for relatively small, contained electrical systems such as those serving a small ship, building, or factory with a limited number of devices to monitor. In a series of tests on a Coast Guard cutter based in Boston, the system provided a dramatic demonstration last year.

About 20 different motors and devices were being tracked by a single dashboard, connected to two different sensors, on the cutter USCGC Spencer. The sensors, which in this case had a hard-wired connection, showed that an anomalous amount of power was being drawn by a component of the ship’s main diesel engines called a jacket water heater. At that point, Leeb says, crewmembers were skeptical about the reading but went to check it anyway. The heaters are hidden under protective metal covers, but as soon as the cover was removed from the suspect device, smoke came pouring out, and severe corrosion and broken insulation were clearly revealed.

“The ship is complicated,” Leeb says. “It’s magnificently run and maintained, but nobody is going to be able to spot everything.”

Lt. Col. Nicholas Galanti, engineer officer on the cutter, says “the advance warning from NILM enabled Spencer to procure and replace these heaters during our in-port maintenance period, and deploy with a fully mission-capable jacket water system. Furthermore, NILM detected a serious shock hazard and may have prevented a class Charlie [electrical] fire in our engine room.”

The system is designed to be easy to use with little training. The computer dashboard features dials for each device being monitored, with needles that will stay in the green zone when things are normal, but swing into the yellow or red zone when a problem is spotted.

Detecting anomalies before they become serious hazards is the dashboard’s primary task, but Leeb points out that it can also perform other useful functions. By constantly monitoring which devices are being used at what times, it could enable energy audits to find devices that were turned on unnecessarily when nobody was using them, or spot less-efficient motors that are drawing more current than their similar counterparts. It could also help ensure that proper maintenance and inspection procedures are being followed, by showing whether or not a device has been activated as scheduled for a given test.

“It’s a three-legged stool,” Leeb says. The system allows for “energy scorekeeping, activity tracking, and condition-based monitoring.” But it’s that last capability that could be crucial, “especially for people with mission-critical systems,” he says. In addition to the Coast Guard and the Navy, he says, that includes companies such as oil producers or chemical manufacturers, who need to monitor factories and field sites that include flammable and hazardous materials and thus require wide safety margins in their operation.

One important characteristic of the system that is attractive for both military and industrial applications, Leeb says, is that all of its computation and analysis can be done locally, within the system itself, and does not require an internet connection at all, so the system can be physically and electronically isolated and thus highly resistant to any outside tampering or data theft.

Although for testing purposes the team has installed both hard-wired and noncontact versions of the monitoring system — both types were installed in different parts of the Coast Guard cutter — the tests have shown that the noncontact version could likely produce sufficient information, making the installation process much simpler. While the anomaly they found on that cutter came from the wired version, Leeb says, “if the noncontact version was installed” in that part of the ship, “we would see almost the same thing.”

The research team also included graduate students Daisy Green, Jennifer Switzer, Thomas Kane, and Peer Lindahl at MIT; Gregory Bredariol of the U.S. Coast Guard; and John Donnal of the U.S. Naval Academy in Annapolis, Maryland. The research was funded by the U.S. Navy’s Office of Naval Research NEPTUNE project, through the MIT Energy Initiative.

“This is the rex of rexes,” said Scott Persons, lead author of the study and postdoctoral researcher in the Department of Biological Sciences. “There is considerable size variability among Tyrannosaurus. Some individuals were lankier than others and some were more robust. Scotty exemplifies the robust. Take careful measurements of its legs, hips, and even shoulder, and Scotty comes out a bit heftier than other T. rex specimens.”

Scotty, nicknamed for a celebratory bottle of scotch the night it was discovered, has leg bones suggesting a living weight of more than 8,800 kg, making it bigger than all other carnivorous dinosaurs. The scientific work on Scotty has been a correspondingly massive project.

The skeleton was first discovered in 1991, when paleontologists including T. rex expert and UAlberta professor Phil Currie were called in on the project. But the hard sandstone that encased the bones took more than a decade to remove — only now have scientists been able to study Scotty fully-assembled and realize how unique a dinosaur it is.

It is not just Scotty’s size and weight that set it apart. The Canadian mega rex also lays claim to seniority.

“Scotty is the oldest T. rex known,” Persons explains. “By which I mean, it would have had the most candles on its last birthday cake. You can get an idea of how old a dinosaur is by cutting into its bones and studying its growth patterns. Scotty is all old growth.”

But age is relative, and T. rexes grew fast and died young. Scotty was estimated to have only been in its early 30s when it died.

“By Tyrannosaurus standards, it had an unusually long life. And it was a violent one,” Persons said. “Riddled across the skeleton are pathologies — spots where scarred bone records large injuries.”

Among Scotty’s injures are broken ribs, an infected jaw, and what may be a bite from another T. rex on its tail — battle scars from a long life.

“I think there will always be bigger discoveries to be made,” said Persons “But as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science.”

A new exhibit featuring the skeleton of Scotty is set to open at the Royal Saskatchewan Museum in May 2019.

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Developed by Vanderbilt mechanical engineers, the device is believed to be the first ankle exoskeleton that could be worn under clothes without restricting motion. It does not require additional components such as batteries or actuators carried on the back or waist.

The study, published online by IEEE Transactions on Neural Systems & Rehabilitation Engineering, builds on a successful and widely cited ankle exoskeleton concept from other researchers in 2015.

“We’ve shown how an unpowered ankle exoskeleton could be redesigned to fit under clothing and inside/under shoes so it more seamlessly integrates into daily life,” said Matt Yandell, a mechanical engineering Ph.D. student and lead author of the study.

In a significant design advancement, the team invented an unpowered friction clutch mechanism that fits under the foot or shoe and is no thicker than a typical shoe insole. The complete device, which includes a soft shank sleeve and assistive spring, weighs just over one pound.

The unpowered ankle exoskeleton costs less than $100 to fabricate, without factoring in optimized design for manufacturing and economies of scale.

“Our design is lightweight, low profile, quiet, uses no motor or batteries, it is low cost to manufacture, and naturally adapts to different walking speeds to assist the ankle muscles,” said Karl Zelik, assistant professor of mechanical engineering and senior author on the study.

Zelik will be presenting this work next week at the Wearable Robotics Association Conference in Phoenix, Arizona.

The potential applications are broad, from helping aging people stay active to assisting recreational walkers, hikers or runners, he said.

“It could also help reduce fatigue in occupations that involve lots of walking, such as postal and warehouse workers, and soldiers in the field,” Zelik said.

Joshua Tacca, BE’18, also is a co-author. He is now a graduate student in the Integrative Physiology Department at the University of Colorado-Boulder. Several other Vanderbilt undergraduate engineering students also contributed to the device design and pilot testing.

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Organic electronics have the potential to revolutionize technology with their high cost-efficiency and versatility compared with more commonly used inorganic electronics. For example, their flexibility could allow companies to print them like paper or incorporate them into clothing to power wearable electronics. However, they have failed to gain much industry traction due to the difficulty of controlling their electronic structure.

To help address this challenge, Nick Jackson, a Maria Goeppert Mayer Fellow at the U.S. Department of Energy’s (DOE) Argonne National Laboratory, has developed a faster way of creating molecular models by using machine learning. Jackson’s models dramatically accelerate the screening of potential new organic materials for electronics and they could also be useful in other areas of materials science research.

The internal structure of an organic material affects its electrical efficiency. The current manufacturing processes used to produce these materials are sensitive, and the structures are extremely complex. This makes it difficult for scientists to predict the final structure and efficiency of the material based on manufacturing conditions. Jackson uses machine learning, a way of training a computer to learn a pattern without being explicitly programmed, to help make these predictions.

Jackson’s research focuses on vapor deposition as a means to assemble materials for organic electronics. In this process, scientists evaporate an organic molecule and allow it to slowly condense on a surface, producing a film. By manipulating certain deposition conditions, the scientists can finely tune the way the molecules pack in the film.

“It’s kind of like a game of Tetris,” said Jackson. “The molecules can orient themselves in different ways, and our research aims to determine how that structure influences the electronic properties of the material.”

The packing of the molecules in the film affects the material’s charge mobility, a measure of how easily charges can move inside it. The charge mobility plays a role in the efficiency of the material as a device. To study this relationship, and to optimize device performance, Jackson’s team runs extremely detailed computer simulations of the vapor deposition process.

“We have models that simulate the behavior of all of the electrons around each molecule at nanoscopic length and time scales,” said Jackson, “but these models are computationally intensive, and therefore take a very long time to run.”

To simulate the packing of entire devices, often containing millions of molecules, scientists must develop computationally cheaper, coarser models that describe the behavior of electrons in groups of molecules rather than individually. These coarse models can reduce computation time from hours to minutes, but the challenge is in making the coarse models truly predictive of the physical results. Jackson uses his machine learning algorithms to uncover the relationships between the detailed and coarse models.

“I drop my hands and leave it to machine learning to regress the relationship between the coarse description and the resulting electronic properties of my system,” Jackson said.

Using an artificial neural network and a learning process called backpropagation, the machine learning algorithm learns to extrapolate from coarse to more detailed models. Using the complex relationship that it finds between the models, it trains itself to predict the same electronic properties of the material using the coarse model as the detailed model would predict.

“We are developing cheaper models that still reproduce all of the expensive properties,” said Jackson.

The resulting coarse model allows the scientists to screen two to three orders of magnitude more packing arrangements than before. The results of the analysis from the coarse model then help experimentalists to more quickly develop high-performance materials.

Shortly after Jackson began his appointment under University of Chicago professor and Argonne Senior Scientist Juan de Pablo, he had the idea to accelerate his research with machine learning. He then took advantage of the laboratory’s high-performance computing capabilities by collaborating with Venkatram Vishwanath, Data Sciences and Workflows Team Lead with the Argonne Leadership Computing Facility, a DOE Office of Science User Facility.

Materials scientists have used machine learning before to find relationships between molecular structure and device performance, but Jackson’s approach is unique, as it aims to do this by enhancing the interaction between models of different length and time scales.

“In the physics community, researchers try to understand the properties of a system from a coarser perspective and to reduce the number of degrees of freedom to simplify it as much as possible,” said Jackson.

Although the targeted goal of this research is to screen vapor deposited organic electronics, it has potential application in many kinds of polymer research, and even fields such as protein science. “Anything where you are trying to interpolate between a fine and coarse model,” he added.

In addition to its broader applications, Jackson’s advancements will help propel organic electronics towards industrial relevance.

“It is difficult to get good quality data about how much water is in intermittent rivers. Most of our existing infrastructure for measuring river flows in the United States is geared towards monitoring water levels of perennial rivers, which are those that always flow. Citizen science groups provide valuable contributions to the field of river science, as the data they produce would not be available otherwise. Without that data we wouldn’t be able to answer basic research questions like how the length of wet river reaches in these rivers has changed over time, and what these changes might mean for fish that live in these rivers,” said Daniel Allen, assistant professor in the Department of Biology, OU College of Arts and Sciences.

In this study, these three groups of citizen scientists divide up and measure the river using a simple method that includes measuring the river from where it begins to where it ends in places where there is at least 30 feet of water. The three long-term wet and dry datasets produced by citizen science river monitoring programs describe landscape drying patterns, examine how they vary over time and use models to quantify landscape drying patterns and temperature, precipitation, stream flow and drought metrics.

While trained citizen scientists conducted the wet and dry surveys on each of these rivers, Friends of the Agua Fria National Monument organize the Agua Fria River surveying effort. The Nature Conservancy and the U.S. Bureau of Land Management organize the upper Cienega Creek surveys, and the Pima County Association of Governments organize surveys of the lowest reaches of Cienega Creek. The Nature Conservancy and the U.S. Bureau of Land Management organize surveys on the San Pedro River.

The data from these surveys is used to generate maps on long-term trends in the three rivers. Two of the rivers measured in this study, the Cienega Creek and the Agua Fria River, showed significant decline. The San Pedro is the only one of three rivers did not decline, which may be due to a groundwater management resource plan in effect. It may be that the declining rivers have no protection and groundwater use has increased during the recent droughts in the area, leading to surface water declines.

Changes in landscape drying patterns in intermittent rivers have strong implications for fish connectivity and bird migration. Drying patterns are likely to decrease connectivity for native fish who need long stretches of unbroken river to reproduce. Rivers in this region are important for the millions of birds that migrate from South America and stop in the region on their way north. The cottonwood and willow trees where they roost during resting periods are typically only found next to rivers where there is water year round. The southwestern United States has experienced large droughts over the past several decades, and the extent of river drying will likely continue as a result of climate change.

Citizen science programs focused on mapping wet and dry sections of rivers and streams are valuable and could be expanded unmonitored intermittent rivers. New technologies, such as smartphone applications, are being developed to improve efforts and aid in integrating data collected by different programs. This type of program could be expanded across the United States to study the variables impacting intermittent rivers in different climates and by different intensities of human water use.

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However, mysteries still remain about why nearby volcanoes often have radically different histories of eruption or erupt different types of magma. Now scientists would like to find out why — both for the Cascades and for other volcanic ranges.

In a perspective essay published today (March 22) in Nature Communications, scientists argue for more “synthesis” research looking at the big picture of volcanology to complement myriad research efforts looking at single volcanoes.

“The study of volcanoes is fascinating in detail, and it has largely been focused on research into individual volcanoes rather than the bigger picture,” said Adam Kent, a volcano expert at Oregon State University and a co-author on the essay. “We now have the insight and data to go beyond looking at just Mount St. Helens and other well-known volcanoes. We can take a step back and ask why is St. Helens different from Mount Adams, why is that different from Mount Hood?”

The study takes a novel approach to this topic. “One way to do this is to consider the heat it took to create each of the volcanoes in the Cascades Arc, for example, and also compare this to the local seismic wave speeds and heat flow within the crust, Kent said. “Linking these diverse data sources together this way gives us a better glimpse into the past, but offer some guidance on what we might expect in the future.”

The need for studying volcanoes more thoroughly is simple, noted Christy Till of Arizona State University, lead author of the Nature Communications essay.

Worldwide almost a billion people live in areas at risk from volcanic eruptions, 90 percent of which live in the so-called Pacific Ring of Fire.

The subduction of the Juan de Fuca tectonic plate beneath the North American plate is the ultimate driver for the formation of the Cascade Range, as well as many of the earthquakes the Northwest has experienced. Subduction results in deep melting of the Earth’s mantle, and the magma then heads upward towards the crust and surface, eventually reaching the surface to produce volcanoes.

But there are differences among the volcanoes, the researchers note, including in the north and south of the Cascade Range.

“The volcanoes in the north stand out because they stand alone,” Kent said. “In the south, you also have recognizable peaks like the Three Sisters and Mount Jefferson, but you also many thousands of smaller volcanoes like Lava Butte and those in the McKenzie Pass area in between. Our work suggests that, together with the larger volcanoes, these small centers require almost twice the amount of magma being input into the crust in the southern part of the Cascade Range.”

Why is that important?

“If you live around a volcano, you have to be prepared for hazards and the hazards are different with each different type of volcano,” Kent said. “The northern Cascades are likely to have eruptions in the future, but we know where they’ll probably be — at the larger stratovolcanoes like Mount Rainier, Mount Baker and Glacier Peak. In the south the larger volcanoes might also have eruptions, but then we have these large fields of smaller — so called ‘monogenetic’ volcanoes. For these it is harder to pinpoint where future eruptions will occur.”

The field of volcanology has progressed quite a bit, the researchers acknowledge, and the need now exists to integrate some of the methodology of individual detailed studies to give a more comprehensive look at the entire volcanic system. The past is the best informer of the future.

“If you look at the geology of a volcano, you can tell what kind of eruption is most likely to happen,” Kent said. “Mount Hood, for example, is known to have had quite small eruptions in the past, and the impact of these is mostly quite local. Crater Lake, on the other hand, spread ash across much of the contiguous United States.

“What we would like to know is why one volcano turns out to be a Mount Hood while another develops into a Crater Lake, with a very different history of eruptions. This requires us to think about the data that we have in new ways.”

The 1980 eruption of Mt. St. Helens was a wake-up call to the threat of volcanoes in the continental United States, and though noteworthy, its eruption was relatively minor. The amount of magma involved in the eruption was estimated to be 1 kilometer cubed (enough to fill about 400,000 Olympic swimming pools), whereas the eruption of Mt. Mazama 6,000 years ago that created Crater Lake was 50 km cubed, or 50 times as great.

The researchers say the process of building and tearing down volcanoes continues today, though it is difficult to observe on a day-to-day basis.

“If you could watch a time-lapse camera over millions of years, you would see volcanoes building up slowly, and then eroding fairly quickly,” said Kent, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Sometimes, both are happening at once.”

Which of the Cascades is most likely to erupt? The smart money is on Mount St. Helens, because of its recent activity, but many of the volcanoes are still considered active.

“I can tell you unequivocally that Mount Hood will erupt in the future,” Kent said. “I just can’t tell you when.”

For the record, Kent said the odds of Mt. Hood erupting in the next 30 to 50 years are less than 5 percent.