It’s no small feat to measure the rate at which objects move away from each other across vast distances. Since the discovery of cosmic expansion, its rate has been measured and re-measured with increasing precision, with some of the latest values ranging from 67.4 up to 76.5 kilometers per second per megaparsec, which relates the recession velocity (in kilometers per second) to the distance (in megaparsecs).

The discrepancy between different measurements of cosmic expansion is called the “Hubble tension.” Some have called it a crisis in cosmology. But for UC Santa Barbara theoretical astrophysicist Tejaswi Venumadhav Nerella and colleagues at the Tata Institute of Fundamental Research in Bangalore, India, and the Inter-University Center for Astronomy and Astrophysics in Pune, India, it is an exciting time.

Since the first detection of gravitational waves in 2015, detectors have been significantly improved and are poised to yield a rich haul of signals in the coming years. Nerella and his colleagues have come up with a method to use these signals to measure the universe’s expansion, and perhaps help to settle the debate once and for all. “A major scientific goal of future detectors is to deliver a comprehensive catalog of gravitational wave events, and this will be a completely novel use of the remarkable dataset,” said Nerella, co-author of a paper published in Physical Review Letters.

Measurements of the cosmic expansion rate boil down to velocity and distance. Astronomers use two kinds of methods to measure distances: the first start with objects with a known length (“standard rulers”) and look at how big they appear in the sky. These “objects” are features in cosmic background radiation, or in the distribution of galaxies in the universe.

A second class of methods starts with objects of known luminosity (“standard candles”) and measures their distances from Earth using their apparent brightness. These distances are connected to those of farther bright objects and so on, which builds up a chain of measurement schemes that is often called the “cosmic distance ladder.” Incidentally, gravitational waves themselves can also help measure cosmic expansion, since the energy released by the collision of neutron stars or black holes can be used to estimate the distance to these objects.

The method that Nerella and his co-authors propose belongs to the second class but uses gravitational lensing. This is a phenomenon that occurs when massive objects warp spacetime, and bend waves of all kinds that travel near the objects. In rare cases, lensing can produce multiple copies of the same gravitational wave signal that reach Earth at different times — the delays between the signals for a population of multiple imaged events can be used to calculate the universe’s expansion rate, according to the researchers.

“We understand very well just how sensitive gravitational wave detectors are, and there are no astrophysical sources of confusion, so we can properly account for what gets into our catalog of events,” Nerella said. “The new method has sources of error that are complementary to those of existing methods, which makes it a good discriminator.”

The sources of these signals would be binary black holes: systems of two black holes that orbit each other and ultimately merge, releasing massive amounts of energy in the form of gravitational waves. We haven’t yet detected strongly lensed examples of these signals, but the upcoming generation of ground-based detectors is expected to have the necessary level of sensitivity.

“We expect the first observation of lensed gravitational waves in the next few years,” said study co-author Parameswaran Ajith. Additionally, these future detectors should be able to see farther into space and detect weaker signals.

The authors expect these advanced detectors to start their search for merging black holes in the next decade. They anticipate recording signals from a few million black hole pairs, a small fraction (about 10,000) of which will appear multiple times in the same detector due to gravitational lensing. The distribution of the delays between these repeat appearances encodes the Hubble expansion rate.

According to lead author Souvik Jana, unlike other methods of measurement, this method does not rely on knowing the exact locations of, or the distances to, these binary black holes. The only requirement is to accurately identify a sufficiently large number of these lensed signals. The researchers add that observations of lensed gravitational waves can even provide clues on other cosmological questions, such as the nature of the invisible dark matter that makes up much of the energy content of the universe.

A first-of-its-kind robotic glove is lending a “hand” and providing hope to piano players who have suffered a disabling stroke. Developed by researchers from Florida Atlantic University’s College of Engineering and Computer Science, the soft robotic hand exoskeleton uses artificial intelligence to improve hand dexterity.

Combining flexible tactile sensors, soft actuators and AI, this robotic glove is the first to “feel” the difference between correct and incorrect versions of the same song and to combine these features into a single hand exoskeleton.

“Playing the piano requires complex and highly skilled movements, and relearning tasks involves the restoration and retraining of specific movements or skills,” said Erik Engeberg, Ph.D., senior author, a professor in FAU’s Department of Ocean and Mechanical Engineering within the College of Engineering and Computer Science, and a member of the FAU Center for Complex Systems and Brain Sciences and the FAU Stiles-Nicholson Brain Institute. “Our robotic glove is composed of soft, flexible materials and sensors that provide gentle support and assistance to individuals to relearn and regain their motor abilities.”

Researchers integrated special sensor arrays into each fingertip of the robotic glove. Unlike prior exoskeletons, this new technology provides precise force and guidance in recovering the fine finger movements required for piano playing. By monitoring and responding to users’ movements, the robotic glove offers real-time feedback and adjustments, making it easier for them to grasp the correct movement techniques.

To demonstrate the robotic glove’s capabilities, researchers programmed it to feel the difference between correct and incorrect versions of the well-known tune, “Mary Had a Little Lamb,” played on the piano. To introduce variations in the performance, they created a pool of 12 different types of errors that could occur at the beginning or end of a note, or due to timing errors that were either premature or delayed, and that persisted for 0.1, 0.2 or 0.3 seconds. Ten different song variations consisted of three groups of three variations each, plus the correct song played with no errors.

To classify the song variations, Random Forest (RF), K-Nearest Neighbor (KNN) and Artificial Neural Network (ANN) algorithms were trained with data from the tactile sensors in the fingertips. Feeling the differences between correct and incorrect versions of the song was done with the robotic glove independently and while worn by a person. The accuracy of these algorithms was compared to classify the correct and incorrect song variations with and without the human subject.

Results of the study, published in the journal Frontiers in Robotics and AI, demonstrated that the ANN algorithm had the highest classification accuracy of 97.13 percent with the human subject and 94.60 percent without the human subject. The algorithm successfully determined the percentage error of a certain song as well as identified key presses that were out of time. These findings highlight the potential of the smart robotic glove to aid individuals who are disabled to relearn dexterous tasks like playing musical instruments.

Researchers designed the robotic glove using 3D printed polyvinyl acid stents and hydrogel casting to integrate five actuators into a single wearable device that conforms to the user’s hand. The fabrication process is new, and the form factor could be customized to the unique anatomy of individual patients with the use of 3D scanning technology or CT scans.

“Our design is significantly simpler than most designs as all the actuators and sensors are combined into a single molding process,” said Engeberg. “Importantly, although this study’s application was for playing a song, the approach could be applied to myriad tasks of daily life and the device could facilitate intricate rehabilitation programs customized for each patient.”

Clinicians could use the data to develop personalized action plans to pinpoint patient weaknesses, which may present themselves as sections of the song that are consistently played erroneously and can be used to determine which motor functions require improvement. As patients progress, more challenging songs could be prescribed by the rehabilitation team in a game-like progression to provide a customizable path to improvement.

“The technology developed by professor Engeberg and the research team is truly a gamechanger for individuals with neuromuscular disorders and reduced limb functionality,” said Stella Batalama, Ph.D., dean of the FAU College of Engineering and Computer Science. “Although other soft robotic actuators have been used to play the piano; our robotic glove is the only one that has demonstrated the capability to ‘feel’ the difference between correct and incorrect versions of the same song.”

Study co-authors are Maohua Lin, first author and a Ph.D. student; Rudy Paul, a graduate student; and Moaed Abd, Ph.D., a recent graduate; all from the FAU College of Engineering and Computer Science; James Jones, Boise State University; Darryl Dieujuste, a graduate research assistant, FAU College of Engineering and Computer Science; and Harvey Chim, M.D., a professor in the Division of Plastic and Reconstructive Surgery at the University of Florida.

This research was supported by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health (NIH), the National Institute of Aging of the NIH and the National Science Foundation. This research was supported in part by a seed grant from the FAU College of Engineering and Computer Science and the FAU Institute for Sensing and Embedded Network Systems Engineering (I-SENSE).

Reported in the journal Chem, the study shows that the ladder-type molecule serves as a robust and reversible molecular switch over a wide range of conductivity levels and different molecular states.

“Our work provides a significant step forward towards the development of functional molecular electronic devices,” says Charles Schroeder, who is the James Economy Professor of Materials Science and Engineering and Professor of Chemical and Biomolecular Engineering at the University of Illinois Urbana-Champaign.

To enhance the chemical and mechanical stability of the molecule, the team used new strategies in chemical synthesis to lock the molecular backbone to prevent the molecule from rotating, like converting a rope ladder into something more stable like metal or wood.

“Imagine a light switch that we turn on and off every day, but instead of flipping an actual switch, we add chemical or electrochemical stimuli to turn the electrical signal from the material on and off,” says lead author and former graduate student Jialing (Caroline) Li. Compared to bulk inorganic materials, organic single molecules can be made into basic electrical components, like wires and transistors, and will help enable the ultimate goal of shrinking electrical circuits.

Single-molecule electronic devices are constructed as junctions with a single molecule bridge that is generally anchored to two terminal groups connected to metal electrodes. These devices can be made programmable by using a stimuli-responsive element in the bridge that can be switched on and off by using an array of stimuli such as pH, optical fields, electric fields, magnetic fields, mechanical forces and electrochemical control.

“The molecular scale switch has been a very popular subject in studies of single molecule electronics,” Li explains. “But realizing a multi-state switch on a molecular scale is challenging because we require a material that is conductive and has several different molecular charge states, and we require the material to be very stable so it can be switched on and off for many cycles.”

Though Li explored many other organic materials, the drawback of those materials was that they were not stable in ambient conditions and could break down easily when exposed to oxygen. After searching for the ideal material for a long time, Li struck gold when she stumbled upon a material from a research group at Texas A&M University (collaborators on this project) and immediately identified it as ideal for her purposes.

Modifying the structure by locking the backbone of the molecule prevents hydrolysis, chemical breakdown due to reaction with water, and other degradation reactions from occurring, and makes characterization of the material easier since it cannot rotate and change forms. This rigid, coplanar form enhances the electronic properties of the molecule, making the flow of electrons through the material easier. The ladder-type structure allows for stable molecular charge states when external stimuli are applied that give rise to significantly different levels of conductivity- making multi-state switching possible.

This material meets almost all of the requirements needed to serve in single-molecule electronic devices: it is stable in ambient conditions, can be cycled on/off many times, is conductive (although not as conductive as metal) and has different molecular states accessible to be utilized.

“Researchers have been struggling to minimize the size of the transistor to fit as many as possible on chips for semiconductors, usually using inorganic materials like silicon,” Li says. “An alternative way of doing that is using organic materials like a single-molecule material to conduct the electrons and replace the inorganic counterparts.” The ladder-type structure used in this research shows promise to be used as functional materials for single-molecule transistors.

For now, only one unit of the molecule is used for single-molecule electronics, but it is possible to extend the length to include many repeating units to make a longer molecular wire. The team believes that the material will still be highly conductive, even over a longer distance.

Dr Matthew Luskin, from UQ’s School of the Environment, and his team collated and analysed species population data from across the region, some of it collected with a network of cameras.

“Macaques and wild pigs are taking over Southeast Asia’s disturbed forests,” Dr Luskin said.

“Humans are largely to blame for this by altering forests with logging and establishing palm oil farms which provide food and ideal breeding conditions for these animals.

“We saw that wild boar and macaque numbers were 400 per cent higher in forests near the plantations than in untouched environments.

“These animals take full advantage of the farmland, raiding crops and thriving on calorie-rich foods.”

Setting and monitoring the camera traps provided Dr Luskin with an up-close experience of the exploding numbers.

“I encountered huge troops of macaques in Thailand, Malaysia, and Indonesia — they were everywhere in the forest edges, following us and interfering with our equipment,” Dr Luskin said.

“At first it was frustrating but then was eerie as we became completely surrounded.”

Dr Luskin said there were significant human health risks in the rising pig and macaque populations.

“The wildlife origins of the COVID-19 pandemic show that mammals in human-modified ecosystems often host high pathogen loads and pose serious zoonotic disease risks,” he said.

“Both pigs and macaques are recognised as carriers of diseases that can be transmitted to people and they’re the most common species in a region considered to be the global zoonotic disease hotspot.”

Collaborator, Professor Carlos Peres from the University of East Anglia (UK), said abnormally high populations of wildlife species that are disease reservoirs often occur in human-modified tropical forests.

“This study again shows that densely settled rural areas in Southeast Asia may be a source of future human epidemics,” he said.

University of East Anglia and Southern University of Science and Technology (China) PhD candidate, Jonathan Moore, said the immediate effects of the population explosions could be seen on native flora in the affected regions.

“Both pigs and macaques trigger negative cascading impacts in these pristine ecosystems,” Mr Moore said.

“They kill the seeds and seedlings of native plants and eat bird and reptile eggs.

“The Malaysian pigs alone were found to reduce rainforest tree regeneration by 62 per cent.”

The researchers say action is needed to minimise population expansions of wild pigs and macaques.

“Efforts to manage the populations of these species have failed in the past because of their rapid reproductive capacity and public outcry,” Dr Luskin said.

“Nobody favours needless killing of wildlife but the negative social and ecological impacts from hyperabundant pest species does demand ethical and urgent management solutions.”

This is now mostly achieved via wired or invasive contact systems. However, these are either inconvenient or, for patients with burns or for infants with insufficient skin area, are unsuitable.

Scientists at the University of Sydney Nano Institute and the NSW Smart Sensing Network have now developed a photonic radar system that allows for highly precise, non-invasive monitoring.

The research is published today in Nature Photonics.

Using their newly developed and patented radar system, the researchers monitored cane toads and were able accurately to detect pauses in breathing patterns remotely. The system was also used on devices that simulate human breathing.

The scientists say this demonstrates a proof of principle for using photonic radar that could enable the vital-sign monitoring of multiple patients from a single, centralised station.

The University of Sydney Pro-Vice-Chancellor (Research) and lead for this research Professor Ben Eggleton said: “Our guiding principle here is to overcome comfort and privacy issues, while delivering highly accurate vital sign monitoring.”

An advantage to this approach is the ability to detect vital signs from a distance, eliminating the need for physical contact with patients. This not only enhances patient comfort but reduces the risk of cross-contamination, making it valuable in settings where infection control is crucial.

“Photonic radar uses a light-based, photonics system — rather than traditional electronics — to generate, collect and process the radar signals. This approach allows for very wideband generation of radio frequency (RF) signals, offering highly precise and simultaneous, multiple tracking of subjects,” said lead author Ziqian Zhang, a PhD student in the School of Physics.

“Our system combined this approach with LiDAR — light detection and ranging. This hybrid approach delivered a vital sign detection system with a resolution down to six millimetres with micrometre-level accuracy. This is suitable for clinical environments.”

Alternate approaches to non-contact monitoring have typically relied on optical sensors, using infrared and visible wavelength cameras.

“Camera-based systems have two problems. One is high sensitivity to variations in lighting conditions and skin colour. The other is with patient privacy, with high-resolution images of patients being recorded and stored in cloud computing infrastructure,” said Professor Eggleton who is also the co-Director of the NSW Smart Sensing Network.

Radio frequency (RF) detection technology can remotely monitor vital signs without the need for visual recording, providing built-in privacy protection. Signal analysis, including identification of health signatures, can be performed with no requirement for cloud storage of information.

Co-author Dr Yang Liu, a former PhD student in Professor Eggleton’s team, now based at EPFL in Switzerland, said: “A real innovation in our approach is complementarity: our demonstrated system has the capability to simultaneously enable radar and LiDAR detection. This has inbuilt redundancy; if either system encounters a fault, the other continues to function.”

Conventional RF radar systems, which rely entirely on electronics, have narrow RF bandwidth and therefore have lower-range resolution. This means they cannot separate closely located targets or distinguish them in a cluttered environment.

Relying solely on LiDAR, which uses much shorter light wavelengths, provides improved range and resolution, but has limited penetration abilities through objects such as clothes.

“Our proposed system maximises the utility of both approaches through integrating the photonic and radio frequency technologies,” Mr Zhang said.

Working with collaborators and partners in the NSW Smart Sensing Network, the researchers hope this research provides a platform to develop a cost-effective, high-resolution and rapid-response vital sign monitoring system with application in hospitals and corrective services.

“A next step is to miniaturise the system and integrate it into photonic chips that could be used in handheld devices,” Mr Zhang said.