Making Robotic Assistive Walking More Natural

 

A team of graduate students in Caltech's Advanced Mechanical Bipedal Experimental Robotics Lab (AMBER), led by Professor Aaron Ames, Bren Professor of Mechanical and Civil Engineering and Control and Dynamical Systems, is developing a new method of generating gaits for robotic assistive devices, which aims to guarantee stability and achieve more natural locomotion for different users.

A paper published in IEEE Robotics and Automation Letters outlines the AMBER team's method and represents the first instance of combining hybrid zero dynamics (HZD)—a mathematical framework for generating stable locomotion—with a musculoskeletal model to control a robotic assistive device for walking. The musculoskeletal model is a computational tool to noninvasively measure the relationship between muscle force and joint contact force. HZD is currently used to create stable walking gaits for bipedal robots, and the muscle model represents how much a muscle stretches or contracts with a given joint configuration.

The team demonstrates its approach on a battery-operated, motorized prosthetic leg. The battery powers the motors, which turn the joints. The motor movement is dictated by the mathematical algorithm developed by the researchers.

To create this mathematical algorithm, the AMBER research team recorded the muscle activity of a person walking with a prosthesis that followed the desired motion generated with HZD alone. This was done using electromyography (EMG), in which one electrode is placed on the skin above a specific muscle. Then the team analyzed the EMG activity of a person walking with a prosthesis that followed the desired motion generated by HZD combined with the muscle models. The latter more closely resembles how a human walks without a prosthesis.

Locking Leukemia’s Cellular Escape Hatch

Kris Wood, PhD, associate professor of
Pharmacology and Cancer Biology

Leukemia starts in cells that would normally develop into different types of blood cells. About 61,000 people in the U.S. are diagnosed each year, and depending on the type of leukemia and the age of the patient, five-year survival rates vary between about 20-80%.

After losing a close friend to an aggressive form of leukemia, acute myeloid leukemia (AML), Kris Wood, PhD, associate professor of pharmacology and cancer biology, devoted his research to helping find better treatment options for people with leukemias and lymphomas. He and his colleagues have discovered a potential new drug therapy that is preparing to enter clinical trials.

A new class of drugs called nuclear exportin inhibitors has recently been approved for use to treat cancers. Nuclear exportins are proteins that shuttle other proteins out of the nucleus of a cell. These new drugs stop the shuttle from leaving the station.

“The idea is that if you treat cells with a drug that blocks a nuclear exportin,” Wood said, “its client proteins become trapped in the nucleus.” And while researchers don’t fully understand why this is therapeutic, it works. Wood and his team investigated the mechanisms behind it. Their results were published in Nature Cancer.

First, they treated AML cells with Selinexor, a nuclear exportin inhibitor. At the same time, they used CRISPR screens to knock out thousands of genes across the genome one at a time to identify genes that made the drug work either much better or much worse when knocked out.

Equine eye docs help horse regain sight

Willy was diagnosed with equine recurrent uveitis, a common but harmful complex autoimmune disease among horses. After treatment, Willy regained most of his vision and has a high quality of life.
Source: Provided to Cornell University

Willy, a 3-year-old quarter horse, has a goofy personality and loves to spend time with his many chicken friends at owner Mariah Kauffman’s home in Snyder County, Pennsylvania.

Soon after Willy joined their family, however, Kauffman noticed that every once in a while, his eyes would cloud over, then appear clear the next day. “He started bumping into things and getting cuts on his face,” Kauffman said. “He would run into the fence and spooked easily.”

That’s when she decided to call Willy’s veterinarian, Dr. Jacqueline Rapp of Susquehanna Valley Veterinary.

Rapp quickly referred Willy to the Cornell Equine Hospital for specialty care from Dr. Kelly Knickelbein, assistant clinical professor, alongside ophthalmology residents Dr. Irini Lamkin and Dr. Brittany Schlesener.

The Cornell team diagnosed him with equine recurrent uveitis (ERU), a common but harmful complex autoimmune disease among horses, with both genetic and environmental factors.

study finds living near trails reduces risk for heart disease

The Northeast Pioneers Greenway Is One of the Four Multi-Use Trails in Winnipeg That Was Studied in the Research Project. 
Photo Courtesy of Winnipeg Trails Association

A University of Manitoba-led study found that living close to a trail used for walking, running and cycling leads to an eight per cent reduction in the risk factors for heart disease.

“If you build it, they will come, and maybe even live longer,” said Dr. Jon McGavock, professor of pediatrics and child health at the Max Rady College of Medicine, Rady Faculty of Health Sciences.

The study looked at four multi-use trails in Winnipeg – the Yellow Ribbon Greenway, Northeast Pioneers Greenway, Transcona Trail and Southside Greenway. The trails ranged from four to seven kilometers and are in largely suburban areas.

The study, published in the International Journal of Behavioral Nutrition and Physical Activity, found that the 20 kilometers of trails attracted 5,000 cyclists every week. This added up to 1.6 million cycling trips over a five-year period.

“Since the trails were built in 2012, that adds up to 4,000 to 7,000 fewer Winnipeggers living with a risk factor for heart disease,” said McGavock, who is also an investigator with the Children’s Hospital Research Institute of Manitoba. “Importantly, this health benefit was greatest for people living along the Southside Greenway, the busiest trail.”

Common drug-resistant superbug develops fast resistance to 'last resort' antibiotic

Pseudomonas under a microscope
Credit: Sean Booth

New research has found that Pseudomonas bacterium develops resistance much faster than usual to a common ‘last-resort’ antibiotic.

A study published today in Cell Reports reveals how populations of a bacterium called Pseudomonas respond to being treated with Colistin, a 'last resort' antibiotic for patients who have developed multi-drug resistant infections.

Antibiotics play a key role in human health by helping to combat bacterial infection, but bacteria can evolve resistance to antibiotics patients rely on. Antibiotic-resistant infections now cause >1 million deaths worldwide per year.

With a small number of ‘last-resort’ antibiotics available, researchers from the University of Oxford are investigating the processes that drive the rise, and fall, of resistance in common bacterial pathogen populations, which is key to tackling the increase in antimicrobial resistance (AMR).

Integration leads to leap in tech for forest inventory and management

Credit: Purdue University

Through integration of aerial and ground-based mobile mapping sensors and systems, a team of Purdue digital forestry researchers has used advanced technology to locate, count and measure over a thousand trees in a matter of hours.

“The machines are counting and measuring each tree – it is not an estimation using modeling, it is a true forest inventory,” said Songlin Fei, the Dean's Remote Sensing Chair and professor of forestry and natural resources and leader of Purdue University’s Digital Forestry initiative. “This is a groundbreaking development on our path to using technology for a quick, accurate inventory of the global forest ecosystem, which will improve our ability to prevent forest fires, detect disease, perform accurate carbon counting and make informed forest management decisions.”

The technology uses manned aircraft, unmanned drones and backpack-mounted systems. The systems integrate cameras with light detection and ranging units, or LiDAR, together with navigation sensors, including integrated global navigation satellite systems (GNSS) and inertial navigation systems (INS). A Purdue team led by Ayman Habib, Thomas A. Page Professor of Civil Engineering and head of Purdue's Digital Photogrammetry Research Group, who co-led the project with Fei, designed and created the systems.

Exotic tree plantations can disturb local wildlife, researchers find

Canthon fulgidus, a roller-dung beetle species in the study region
Credit: Dr Filipe França

Initiatives using non-native tree species can impact tropical insects in neighboring forests, according to an international study.

Scientists at the University of Bristol and Federal University of Western Pará, in Brazil have found that Eucalyptus plantation edge effects radiates up to 800 meters into the interior of nearby Amazonian forests, when applied to ecologically important dung beetles.

As the world seeks to mitigate human-induced climate change, planted forests have become widespread restoration strategies across the globe. However, the findings, published today in Forest Ecology and Management, suggest that while well-intentioned, exotic tree plantations can have a wider influence on the native biodiversity of hyperdiverse tropical forests.

In ecology, edge effect research investigates how biological populations or communities change at the boundary of two or more habitats.

Yolk-Shell Nanocrystals with Movable Gold Yolk: Next Generation of Photocatalysts

The synthesis of yolk-shell nanostructures involves sulfidation on an Au@Cu2O core-shell nanocrystal template to convert the shell composition to various metal sulphides.
Credit: Tokyo Institute of Technology

Owing to their unique permeable, hollow shell structures with inner, movable cores, yolk-shell nanocrystals are suitable for a wide variety of applications. Yolk-shell nanocrystals consisting of a gold core with various semiconductor shells have been developed by Tokyo Tech researchers, using a novel sequential ion-exchange process. These metal-semiconductor yolk-shell nanocrystals can serve as highly effective photocatalysts for many applications.

Yolk-shell nanocrystals are unique materials with fascinating structural properties, such as a permeable shell, interior void space, and movable yolk. These nanocrystals are suitable for a variety of applications, depending on the choice of materials used for their fabrication.

For example, if the inner surface of their shells are reflective, yolk-shell nanocrystals can make for a reliable photovoltaic device. A mobile core can can act as a stirrer, capable of mixing solutions held within the shell. The inner and outer surfaces of the shell provide plenty of active sites for reactions, and the yolk-shell structure's fascinating properties (a result of electronic interactions and charge-transfer between the surfaces of the structure) make these nanocrystals ideal for photocatalysis applications. Understandably, yolk-shell nanocrystals have earned the attention of researchers worldwide.

New Study Deepens Understanding of How Animals See, and What Colors

 Researchers determined that animals adapted to land see more colors than animals adapted to water. Animals adapted to open terrestrial habitats see a wider range of colors than animals adapted to forests.
 Credit: Artwork by Matt Murphy

Gathering vision data for hundreds of vertebrates and invertebrates, U of A biologists have deepened scientists’ understanding of animal vision, including the colors they see.

Researchers have determined that animals adapted to land are able to see more colors than animals adapted to water. Animals adapted to open terrestrial habitats see a wider range of colors than animals adapted to forests.

However, evolutionary history — primarily the difference between vertebrates and invertebrates — significantly influences which colors a species sees. Invertebrates see shorter wavelengths of light, compared to vertebrates.

Biological sciences doctoral student Matt Murphy and assistant professor Erica Westerman recently published these findings in Proceedings of the Royal Society B, a top British scientific journal. Their article, “Evolutionary history limits species’ ability to match color sensitivity to available habitat light,” explains how environment, evolution and, to some extent, genetic composition influence how and what colors animals see.

Copper makes seed pods explode

A stiff polymer called lignin (stained red) is deposited in a precise pattern in the cell walls of exploding seed pods. Researchers identified three laccase enzymes required to form this lignin. No lignin forms in the cell wall (stained blue) when all three genes are knocked out by CRISPR/Cas9 gene editing. 
Credit: Miguel Pérez Antón

Plants have evolved numerous strategies to spread their seeds widely. Some scatter their seeds to the wind, while others tempt animals and birds to eat their seed-filled fruits. And a few rare plants – such as the popping cress Cardamine hirsuta – have evolved exploding seed pods that propel their seeds in all directions. In their new study published in PNAS, Angela Hay and colleagues – from the Max Planck Institute for Plant Breeding Research in Cologne, Germany – investigate what genes control the mechanical structure of these exploding seed pods. Their findings show that a key micronutrient – copper – is essential for laying down a precise pattern of lignin in the seed pods. Lignin is an abundant plant polymer found in lignocellulose, the main structural material in plants. It is present in plant cells walls and is responsible for making wood stiff.

C. hirsuta seed pods consist of two, long valves. When the seeds are ready for dispersal, these valves rapidly separate and coil back, firing seeds out across a large area. The secret to these pods explosive nature is their unique mechanical design, which features three stiff rods of lignin connected by hinges. These hinges are crucial for the explosive release of potential energy stored in the pod. To create these hinged structures, lignin is deposited in a precise pattern in a single layer of seed pod cells, called endocarpb.