‘Where did I park my car?’ Brain stimulation improves mental time travel

You might remember you ate cereal for breakfast but forget the color of the bowl. Or recall watching your partner put the milk away but can’t remember on which shelf. A new Northwestern Medicine study improved memory of complex, realistic events similar to these by applying transcranial magnetic stimulation (TMS) to the brain network responsible for memory.

Experimental design overview

The study authors used TMS with the goal of altering brain activity and memory for realistic events. Immediately following stimulation, subjects performed a memory task while having their brains scanned using functional magnetic resonance imaging (fMRI). Instead of showing study participants pictures or lists of words — typical practices in laboratory tests that analyze memory — participants in this study watched videos of everyday activities such as such as someone folding laundry or taking out the garbage.

Following stimulation, study participants more accurately answered questions about the content of the video clips, such as identifying the shirt color an actor was wearing or the presence of a tree in the background. Additionally, the study found that brain stimulation led to higher quality reinstatement of memories in the brain, which happens when the brain replays or relives an original event. Following stimulation, a person’s brain activity while watching a video more closely resembled their brain activity when remembering that same video.

Adapted and abridged from Source

Original paper: Hebscher, M., Kragel, J.E., Kahnt, T. and Voss, J.L., 2021. Enhanced reinstatement of naturalistic event memories due to hippocampal-network-targeted stimulation. Current Biology.

A guide to making high-performance, versatile solar cells

Improving solar cell design is integral for improving energy consumption. Scientists have lately focused on making solar cells more efficient, flexible, and portable to enable their integration into everyday applications. Consequently, novel lightweight and flexible thin film solar cells have been developed. It is, however, not easy to combine efficiency with flexibility. For a material (usually a semiconductor) to be efficient, it must have a small “band gap” — the energy required to excite charge carriers for electrical conduction — and should absorb and convert a large portion of the sunlight into electricity. Till date, no such efficient absorber suitable for thin film solar cells has been developed.

In a new study published in Applied Materials and Interfaces, scientists from Korea addressed this issue and proposed a novel solution in the form of “antiperovskite” oxides, denoted as Ba4Pn2O, with Pn as stand-in for Arsenic (As) or Antimony (Sb). Using density functional theory calculations, scientists investigated various physical properties of the antiperovskite oxides and revealed that they exhibit spontaneous electric polarization, making them ferroelectric in nature. Prof. Youngho Kang from Incheon National University, who led the study, explains, In the minimum energy configuration of the Ba4Pn2O structure, we found that the O ions and the Ba ions are displaced from their original positions in opposite directions. These displacements gave rise to a non-zero electric polarization, a classic signature of ferroelectricity.”

Since the spontaneous polarization assists in the separation of eleat their band gaps are ideal for efficient sunlight absorption,ctron-hole pairs, this implied that antiperovskite oxides could efficiently extract charge carriers. In addition, the calculations showed th allowing even a very thin layer of Ba4Pn2O to yield substantial photocurrent.

Adapted and abridged from Source

Original paper: Kang, Y. and Han, S., 2020. Antiperovskite oxides as promising candidates for high-performance ferroelectric photovoltaics: First-principles investigation on Ba4As2O and Ba4Sb2O. ACS Applied Materials & Interfaces12(39), pp.43798-43804.

Urban-Air Port

Urban-Air Port, a British-based start-up, has partnered with car giant Hyundai Motor to develop the infrastructure required for when flying cars take to the skies to ferry around people and goods. An airport for flying cars will thrust the English city of Coventry into the future later this year, with a project aimed at demonstrating how air taxis will work in urban centres.

From November, visitors to Coventry will be able to see what a flying car airport looks like and see a passenger-carrying drone and an operational electric vertical take-off and landing (eVTOL) vehicle on the landing pad. Urban-Air Port was selected by a government programme aimed at developing zero-emission flying and new air vehicles, winning a 1.2-million-pound ($1.65-million) grant to help fund the temporary installation of the airport in Coventry city centre.


Dancing with robots

Meet Atlas, Spot, and Handle on the dance floor.

Adam Savage and the Tested team had a meeting with an engineer from Boston Dynamics to better understand the choreographer software that is able to make these robots dance.

Why independent cultures think alike when it comes to categories: It’s not in the brain

Imagine you gave the exact same art pieces to two different groups of people and asked them to curate an art show. The art is radical and new. The groups never speak with one another, and they organize and plan all the installations independently. On opening night, imagine your surprise when the two art shows are nearly identical. How did these groups categorize and organize all the art the same way when they never spoke with one another?

The dominant hypothesis is that people are born with categories already in their brains, but a study from the Network Dynamics Group (NDG) at the Annenberg School for Communication has discovered a novel explanation. In an experiment in which people were asked to categorize unfamiliar shapes, individuals and small groups created many different unique categorization systems while large groups created systems nearly identical to one another.


If people are so different, why do anthropologists find the same categories, for instance for shapes, colors, and emotions, arising independently in many different cultures? Where do these categories come from and why is there so much similarity across independent populations? “If I assign an individual to a small group, they are much more likely to arrive at a category system that is very idiosyncratic and specific to them,” says lead author and Annenberg alum Douglas Guilbeault (Ph.D. ’20), now an Assistant Professor at the Haas School of Business at the University of California, Berkeley. “But if I assign that same individual to a large group, I can predict the category system that they will end up creating, regardless of whatever unique viewpoint that person happens to bring to the table.”

The explanation is connected to previous work conducted by the NDG on tipping points and how people interact within networks. As options are suggested within a network, certain ones begin to be reinforced as they are repeated through individuals’ interactions with one another, and eventually a particular idea has enough traction to take over and become dominant. This only applies to large enough networks, but according to Centola, even just 50 people is enough to see this phenomenon occur.

Adapted and abridged from Source

Guilbeault, D., Baronchelli, A. & Centola, D. Experimental evidence for scale-induced category convergence across populations. Nat Commun 12, 327 (2021). https://doi.org/10.1038/s41467-020-20037-y

Sound Beaming

Imagine a world where you move around in your own personal sound bubble. You listen to your favorite tunes, play loud computer games, watch a movie or get navigation directions in your car — all without disturbing those around you. That’s the possibility presented by “sound beaming,” a new futuristic audio technology from Noveto.

The technology uses a 3-D sensing module and locates and tracks the ear position sending audio via ultrasonic waves to create sound pockets by the user’s ears. Sound can be heard in stereo or a spatial 3-D mode that creates 360 degree sound around the listener. The company expects the device will have plenty of practical uses, from allowing office workers to listen to music or conference calls without interrupting colleagues to letting someone play a game, movie or music without disturbing their significant others. The lack of headphones means it’s possible to hear other sounds in the room clearly.

Adapted and abridged from Source

Keeping time more precisely with a new type of atomic clock

Atomic clocks are the most precise timekeepers in the world, which use lasers to measure the vibrations of atoms. They keep time with such precision that, if they had been running since the beginning of the universe, they would only be off by about half a second today. Still, they could be even more precise. If atomic clocks could more accurately measure atomic vibrations, they would be sensitive enough to detect phenomena such as dark matter and gravitational waves, which would give answers to questions like what effect gravity might have on the passage of time and whether time itself changes as the universe ages.

The researchers Pedrozo-Peñafiel et al. report in the journal Nature that they have built an atomic clock that measures not a cloud of randomly oscillating atoms, as state-of-the-art designs measure now, but instead atoms that have been quantumly entangled. Their findings would lead to clocks being less than 100 milliseconds off. To keep perfect time, clocks would ideally track the oscillations of a single atom, but they are subject to the Standard Quantum Limit that introduces an uncertainty when measuring at such small scales.

The solution would be quantum entanglement which describes a nonclassical physical state, in which atoms in a group show correlated measurement results, even though each individual atom behaves like the random toss of a coin. The team reasoned that if atoms are entangled, their individual oscillations would tighten up around a common frequency, with less deviation than if they were not entangled. In this way, the researchers quantumly entangle the atoms, and then use another laser, similar to existing atomic clocks, to measure their average frequency. When the team ran a similar experiment without entangling atoms, they found that the atomic clock with entangled atoms reached a desired precision four times faster.  

This version was adapted and abridged from the original MIT article

Original paper: Pedrozo-Peñafiel, E., Colombo, S., Shu, C., Adiyatullin, A.F., Li, Z., Mendez, E., Braverman, B., Kawasaki, A., Akamatsu, D., Xiao, Y. and Vuletić, V., 2020. Entanglement on an optical atomic-clock transition. Nature588(7838), pp.414-418. Online

Voxon Photonics

Earlier this week, Voxon showcased a real-time use case scenario of their innovative photometric display which is capable of displaying data in real time from Blender.

Interactive 3D images that appear to float in the air, above a table that a group of people can stand around without needing any special headsets or glasses: that’s what South Australian company Voxon Photonics has built with its US$10,000 VX1 table. Such things have been a long time coming to the real world. VR and AR can both somewhat replicate the experience, but they require headsets. In the best case, these are a bit antisocial, stopping you from looking others in the eye. In the worst case, they completely remove the wearer from the real world to immerse them in virtual space. The VX1 table from Voxon Photonics, on the other hand, requires no headset or eyewear. It operates more or less exactly like the hologram table in Star Wars, albeit usually with a glass dome over the top of it, and can display an 18x18x8 centimeter holographic image, video, game or interactive data visualization.

The VX1 table can best be described as 3D printing its image in the air. It breaks a 3D form up into horizontal layer slices, then achieves the mind-bending trick of projecting these slices onto a single piece of rear projection glass that’s being flung back and forth in the air at 15 cycles per second on a set of harmonic resonance springs. The system tracks the location of the glass and synchronizes it perfectly with a 4,000 frames per second projector, so that each slice is projected at exactly the right height. The slices are stacked and re-stacked so fast that your eyes can’t track the motion, and an object appears to float in the air. Since it’s being re-drawn both on the up and down swing of the glass, you get a hologram video refresh rate of 30 frames per second, and the illusion is terrific.

Voxon’s glass shaker might not scale up well – bigger versions are much harder to shake back and forth at a rate that gives you a satisfying video frame rate – but the company has another trick or two up its sleeve. Using a rotating screen that looks something like a drill bit, with ramps and drop-offs, it’s possible to make a much larger volumetric display that relies on projectors coming down from above.


New class of cobalt-free cathodes could enhance energy density of next-gen lithium-ion batteries

Oak Ridge National Laboratory researchers have developed a new family of cathodes with the potential to replace the costly cobalt-based cathodes typically found in today’s lithium-ion batteries that power electric vehicles and consumer electronics. The new class called NFA, which stands for nickel-, iron- and aluminum-based cathode, is a derivative of lithium nickelate and can be used to make the positive electrode of a lithium-ion battery. These novel cathodes are designed to be fast charging, energy dense, cost effective, and longer lasting.

With the rise in the production of portable electronics and electric vehicles throughout the world, lithium-ion batteries are in high demand. According to Ilias Belharouak, ORNL’s scientist leading the NFA research and development, more than 100 million electric vehicles are anticipated to be on the road by 2030. Cobalt is a metal currently needed for the cathode which makes up the significant portion of a lithium-ion battery’s cost. Cobalt is rare and largely mined overseas, making it difficult to acquire and produce cathodes. As a result, finding an alternative material to cobalt that can be manufactured cost effectively has become a lithium-ion battery research priority.

“Lithium nickelate has long been researched as the material of choice for making cathodes, but it suffers from intrinsic structural and electrochemical instabilities,” Belharouak said. “In our research, we replaced some of the nickel with iron and aluminum to enhance the cathode’s stability. Iron and aluminum are cost-effective, sustainable and environmentally friendly materials.” Future research and development on the NFA class will include testing the materials in large-format cells to validate the lab-scale results and further explore the suitability of these cathodes for use in electric vehicles.

You can read more in the original paper (this version is adapted and abridged from Source).

Muralidharan, N., Essehli, R., Hermann, R.P., Parejiya, A., Amin, R., Bai, Y., Du, Z. and Belharouak, I., 2020. LiNixFeyAlzO2, a new cobalt-free layered cathode material for advanced Li-ion batteries. Journal of Power Sources471, p.228389.

Romanian designer wins MIT prize for high-tech face mask prototype

A face mask equipped with a sensor that detects Covid-19 particles in the surroundings, designed by a Romanian engineer, has scooped the top prize at a contest from MIT Media Lab.

Burzo Ciprian’s award-winning design, “social mask”, is a minimalist, transparent mask featuring a biosensor that can connect to a smartphone. Via an app, users would be able to track the number of surrounding air-borne pathogens, collecting data that also maps other users around you and calculates the risk of infection with Covid-19.

The design, which is still a prototype under development, won a competition by MIT’s pandemic response lab that asked engineers and designers to come up with creative responses that reimagine face coverings and personal protective equipment (PPE).

“Connecting the mask with our smartphone is a real option for the future,” says Ciprian. “We should know who is infected in our area, and get informed on our smartphone about what the biosensor has detected based on surrounding particles. These are just a few of the options that will surely feature in the mask of the future.”