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April, 2018

Designing a Smart Sensor Network for Tracking Submarines

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Illustration of network concept. (Getty Images)
Illustration of network concept. A UConn researcher at the National Institute for Undersea Vehicle Technology is developing a ‘smart sensor network’ that is both energy-efficient and resilient, to track targets such as enemy submarines. (Getty Images)

A team of UConn engineers is developing an energy-efficient “smart sensor network” to track targets of interest, such as the proximity of enemy submarines or ships to Navy vessels.

The U.S. Navy currently uses underwater Intelligence, Surveillance, & Reconnaissance (ISR) sensor networks that run on full power, which can be a problem for long-term operations. The more accurate the sensor, the more power they consume.

The sensor networks currently being used could consist of several multi-modal sensor nodes, called sensor buoys, where each node acts independently and contains a diverse sensor suite, a data-processing unit, a transmitter and receiver, and a GPS device. The sensor suite can be composed of different types of sensors to detect and track targets, such as underwater microphones and active sonars.

Batteries typically burn out within  a few days,  just as cell phones suck up more power when running multiple operations.

Traditionally, these sensor nodes operate on full power, running all devices simultaneously, but the batteries that power them typically burn out within a few days of operation,  just as cell phones suck up more power when running multiple operations. This causes sensing failures which, in turn, leads to holes in coverage and affects tracking performance.

This poses a challenge to the Navy, since it deploys thousands of acoustic sensor networks throughout the ocean, where battery replacement can be time-consuming or impossible.

To address the challenge, Shalabh Gupta, a UConn engineer and researcher at the National Institute for Undersea Vehicle Technology, devised the concept of a “smart sensor network” that is energy-efficient as well as resilient to failures.

Intelligent Energy-efficient Sensor Network. (Illustration by Hayley Joyal '18 (SFA))
Intelligent Energy-efficient Sensor Network. (Illustration by Hayley Joyal ’18 (SFA))

In a smart sensor network, sensor nodes adapt their sensing modalities based on the information about the targets’ whereabouts. Thus, the nodes around the target, such as a ship or submarine, activate their high-power sensing devices to track the target accurately, pinpointing its location, velocity, and trajectory.

On the other hand, the nodes that are located farther away from the target cycle between low-power sensing and sleep states to minimize energy consumption while still remaining aware.

Thus, if a low-power sensor detects a target, the node switches to high-power sensing to track it. Similarly, the high-power sensing devices that are tracking the target predict the target’s trajectory and alert other sensors within range of the target’s path, so that they switch to high power. Once the target has passed outside of a sensor’s range, it reverts to low-power mode.

The smart sensor networks also provide resilience. If a few nodes in the network fail, then the nodes surrounding the hole in coverage formed by the failed nodes jointly optimize to expand their sensing ranges to cover the gap.

“These networks have to contain built-in, distributed intelligence,” says Gupta, an assistant professor of electrical and computer engineering.

His first research paper on the algorithm, coauthored by graduate student James Hare, was published online in IEEE Transactions on Cybernetics in August 2017.

With this advance, crews on ships and submarines will be able to track enemy watercraft with batteries that last about 60 to 90 percent longer, Gupta says.

Gupta’s lab has prototypes of the sensors for ground use, and has been talking with Navy personnel about using them for the underwater acoustic sensor network.  He is currently seeking funding to build underwater sensors.

Piecing Together Our Planet Pixel by Pixel

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UConn researcher Chandi Witharana is using remote sensing as 'a virtual passport' to monitor vast expanses of land in remote areas, including the Arctic tundra. (Chandi Witharana)
UConn researcher Chandi Witharana is using remote sensing as ‘a virtual passport’ to monitor vast expanses of land in remote areas, including the Arctic tundra. (Torre Jorgenson, University of Alaska-Fairbanks)
At first glance, the high-resolution satellite images of the Arctic tundra look like the lacy skin of a cantaloupe melon. But this characteristic feature of the tundra is perfect for studying the rapidly changing landscape of the region using remote sensing technologies. (Chandi Witharana)
At first glance, the high-resolution satellite images of the Arctic tundra look like the lacy skin of a cantaloupe melon. But this characteristic feature of the tundra is perfect for studying the rapidly changing landscape of the region using remote sensing technologies. (Torre Jorgenson, University of Alaska-Fairbanks)

At first glance, the high-resolution images of the polygons look like the lacy skin of a cantaloupe melon – perhaps not what would be expected of images of the Arctic tundra. But this characteristic feature of the tundra is a perfect focus for remote sensing technologies and for studying the rapidly changing landscape of the region.

From the Antarctic to the Arctic and areas in between, Chandi Witharana is applying powerful remote sensing technology to study global problems.

Witharana, a visiting assistant professor in UConn’s Department of Natural Resources and the Environment, says remote sensing is “a virtual passport” to these remote areas, allowing him to carefully monitor the harsh landscape from his grizzly bear-free computer laboratory on campus.

He and his collaborators are currently mapping thousands of square meters of the Pan-Arctic, using satellite images to collect data. The images offer a resolution so powerful that anything larger than 30 centimeters can be imaged from space, enabling the researchers to study areas across the globe that would be difficult or impossible to survey otherwise.

For the Pan-Arctic project, satellite images are taken roughly every two days, over a massive stretch of land encompassing parts of Alaska, Canada, and Siberia.

Each point or pixel within each image is identified by its geographical location, using latitude and longitude, and this geo-referencing is used to mesh the data together using super computers. The researchers then compare various features between images taken over time, noting changes or trends.

In the Arctic tundra, the researchers are seeing degradation proceeding at an alarming rate.

“Previously it was thought that topography was fixed, needing millions of years to change,” says Witharana. “But this degradation is happening within the span of a decade.”

Without remote sensing technologies, collection of this type of data over such vast expanses of land would be cost-prohibitive, dangerous, and potentially impossible for humans to accomplish, since many areas are remote and cannot be reached even by helicopter.

A satellite image of a refugee camp. (Chanda Witharana)
A satellite image of a refugee camp. (Torre Jorgenson, University of Alaska-Fairbanks )

Remote sensing is also a vital tool for an entirely different kind of extreme – wars and their effects on civilian populations. Working with the United Nations, Witharana studied how people migrate under forced conditions, where refugee settlements are established, and the number of those affected.

Due to the chaos inherent in war, the only unbiased and accurate measures of refugee populations are those gathered using remote sensing, says Witharana. “You cannot trust any other source in conflict situations. It is not possible to report exact numbers from the ground.”

Witharana has not only used the technology for his own research, he has introduced it to K-12 STEM classrooms as part of the Next Generation Science Standards. Using their own virtual passports, students can apply tools like Google Earth and StreetView to go on virtual hikes, exploring the Antarctic landscape and areas such as Deception Island and Bailey Head, and study the penguin population.

After a little tweaking, Witharana says, the technology can become a valuable tool in gathering information about almost anything you are interested in. The possibilities are as vast as the landscapes surveyed.

“This is everyday science, it is artwork, and it is a rich educational tool.”

Witharana is also participating in UConn’s Metanoia on the Environment, and will be holding a satellite image gallery during the week of Earth Day. The gallery will present appealing patterns, shapes, colors, and textures of the natural and human-made landscape, as well as sentient views of forced migration, violence, and destruction triggered by autocracy, racial aggression, and ethnic tension. The intent is to prompt viewers to observe and recognize the beauty in the world, and to contemplate the role humans play in its shaping.

This project is funded by the National Science Foundation Arctic System Science Program Award # 1720875.

New Compound Helps Activate Cancer-Fighting T Cells

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An illustration showing interactions between components of the AH10-7 compound (yellow), an immune system antigen presenting cell (gray) and an invariant natural killer T cell (green and blue) that spark activation of iNKT cells in “humanized” mice. (Image courtesy of Jose Gascon/UConn)
An illustration showing interactions between components of the AH10-7 compound (yellow), an immune system antigen-presenting cell (gray), and an invariant natural killer T cell (green and blue) that spark activation of iNKT cells in ‘humanized’ mice. (Image courtesy of Jose Gascon/UConn)
Researchers Amy Howell and José Gascón of the chemistry department discuss a molecular simulation on a laptop monitor in the academic wing of the Chemistry Building. (Sean Flynn/UConn Photo)
Researchers Amy Howell and José Gascón of the chemistry department discuss a molecular simulation on a laptop monitor in the academic wing of the Chemistry Building. (Sean Flynn/UConn Photo)

Invariant natural killer T (iNKT) cells are powerful weapons our body’s immune systems count on to fight infection and combat diseases like cancer, multiple sclerosis, and lupus. Finding ways to spark these potent cells into action could lead to more effective cancer treatments and vaccines.

While several chemical compounds have shown promise stimulating iNKT cells in mice, their ability to activate human iNKT cells has been limited.

Now, an international team of top immunologists, molecular biologists, and chemists led by University of Connecticut chemistry professor Amy Howell reports in Cell Chemical Biology the creation of a new compound that appears to have the properties researchers have been looking for.

The compound – a modified version of an earlier synthesized ligand – is highly effective in activating human iNKT cells. It is also selective – encouraging iNKT cells to release a specific set of proteins known as Th1 cytokines, which stimulate anti-tumor immunity.

One of the limitations of earlier compounds was their tendency to cause iNKT cells to release a rush of different cytokines. Some of the cytokines turned the body’s immune response on, while others turned it off. The conflicting cytokine activity hampered the compounds’ effectiveness.

The new compound – called AH10-7 – is uniquely structured so that does not happen.

“One of the goals in this field has been to identify compounds that elicit a more biased or selective response from iNKT cells, and we were able to incorporate features in AH10-7 that did that,” says Howell, who has been studying the role of glycolipids in modulating the human immune system for more than 20 years.

The robust study, years in the making, also applied advanced structural and 3-D computer modeling analysis to identify the underlying basis for the new compound’s success. These highly detailed insights into what is happening at the molecular level open up new paths for research and could lead to the development of even more effective compounds.

“We synthesized a new compound, demonstrated its effectiveness with biological data, and learned more about its interactions with proteins through X-ray crystallography and computational analysis,’’ says UConn associate professor of chemistry José Gascón, a specialist in quantum and molecular mechanics. “We are providing protocols so that other scientists can rationally design related molecules that elicit desired responses from iNKT cells.”

The molecular analysis helped validate and explain experimental results.

“By exposing a crystalized form of the molecular complex to a high-intensity X-ray beam at the Australian Synchrotron, we were able to obtain a detailed 3-D image of the molecular interplay between the invariant natural killer T cell receptor and AH10-7,” says corresponding author Jérôme Le Nours, a structural biologist with the Biomedicine Discovery Institute at Monash University in Australia. “This enabled us to identify the structural factors responsible for AH10-7’s potency in activating iNKT cells. This valuable insight could lead to the development of even more effective anti-metastatic ligands.”

Efforts to harness the therapeutic potential of human iNKT cells began 20 years ago with the discovery that natural and synthetic forms of glycolipid ligands known as alpha-galactosylceramides, or α-GalCers for short, were potent activators of iNKT cells. Scientists immediately recognized their possible value in fighting cancer and other diseases. These α-GalCer ligands serve as tiny dock masters in our immune system, helping antigen-presenting cells attract and bind with iNKT cells so they can be activated to kill cancerous cells or fight off pathogens and other foreign invaders.

Comparison of tumor suppression in the lungs of wild mice (top row) and 'humanized' mice (bottom row). First column represents untreated mice. Second column, mice treated with the KRN7000 synthesized compound. Third column, mice treated with the new compound AH10-7. Results show the newly synthesized compound AH10-7 is at least as effective as KRN7000 in suppressing growth of melanoma cells. (Images courtesy of Dr. Steven Porcelli and Weiming Yuan)
Comparison of tumor suppression in the lungs of wild mice (top row) and ‘humanized’ mice (bottom row). First column represents untreated mice. Second column, mice treated with the KRN7000 synthesized compound. Third column, mice treated with the new compound AH10-7. Results show the newly synthesized compound AH10-7 is at least as effective as KRN7000 in suppressing growth of melanoma cells. (Images courtesy of Dr. Steven Porcelli and Weiming Yuan)

The first promising version of a synthesized α-GalCer was a compound known as KRN7000. While KRN7000 powerfully stimulated iNKT cells in both mice and humans, it triggered the release of a flood of many types of cytokines, limiting its potential for clinical applications. Since then, researchers have been searching for new variations of KRN7000 that maintain their effectiveness in activating human iNKT cells while also favoring release of the powerful tumor fighting Th1 cytokines.

In the current study, Howell and colleagues made two significant modifications to an α-GalCer ligand in an attempt to make it more effective. They found that adding a hydrocinnamoyl ester on to the sugar stabilized the ligand and kept it close to the surface of the antigen-presenting cell, thereby enhancing its ability to dock with and stimulate human iNKT cells. In addition, trimming off part of the molecule’s sphingoid base appears to initiate the critical Th1 cytokine bias. Both changes, working in tandem, strengthened the effectiveness of the entire molecular complex in terms of activating human iNKT cells, Howell says.

To further validate AH10-7’s effectiveness, the researchers tested the new compound in wild mice as well as partially “humanized” mice, whose genomes were modified to mimic the human iNKT cell response. Notably, AH10-7 was shown to be at least as effective as KRN7000 in suppressing the growth of melanoma cells in the partially humanized mice.

Dr. Steven Porcelli, an immunologist with the Albert Einstein College of Medicine in N.Y., also served as a corresponding author on the study.

The research was supported in part by NIH grants U01 GM111849, R01 GM087136, R01 AI45889, and R01 AI 091987.

A complete list of the contributing researchers and funding resources for the study “Dual Modifications of α-Galatosylceramide Synergize to Promote Activation of Human Invariant Natural Killer T Cells and Stimulate Anti-tumor Immunity” can be found here.