Aurelia Butler

University at Buffalo researchers are reporting a new, two-dimensional transistor made of graphene and the compound molybdenum disulfide that could help usher in a new era of computing.
As described in a paper accepted at the 2020 IEEE International Electron Devices Meeting, which is taking place virtually next week, the transistor requires half the voltage of current semiconductors. It also has a current density greater than similar transistors under development.
This ability to operate with less voltage and handle more current is key to meet the demand for new power-hungry nanoelectronic devices, including quantum computers.
“New technologies are needed to extend the performance of electronic systems in terms of power, speed, and density. This next-generation transistor can rapidly switch while consuming low amounts of energy,” says the paper’s lead author, Huamin Li, Ph.D., assistant professor of electrical engineering in the UB School of Engineering and Applied Sciences (SEAS).
The transistor is composed of a single layer of graphene and a single layer of molybdenum disulfide, or MoS2, which is a part of a group of compounds known as transition metals chalcogenides. The graphene and MoS2 are stacked together, and the overall thickness of the device is roughly 1 nanometer — for comparison, a sheet of paper is about 100,000 nanometers.
While most transistors require 60 millivolts for a decade of change in current, this new device operates at 29 millivolts.
It’s able to do this because the unique physical properties of graphene keep electrons “cold” as they are injected from the graphene into the MoS2 channel. This process is called Dirac-source injection. The electrons are considered “cold” because they require much less voltage input and, thus, reduced power consumption to operate the transistor.
An even more important characteristic of the transistor, Li says, is its ability to handle a greater current density compared to conventional transistor technologies based on 2D or 3D channel materials. As described in the study, the transistor can handle 4 microamps per micrometer.
“The transistor illustrates the enormous potential 2D semiconductors and their ability to usher in energy-efficient nanoelectronic devices. This could ultimately lead to advancements in quantum research and development, and help extend Moore’s Law,” says co-lead author Fei Yao, PhD, assistant professor in the Department of Materials Design and Innovation, a joint program of SEAS and UB’s College of Arts of Sciences.
The work was supported by the U.S. National Science Foundation, the New York State Energy Research and Development Authority, the New York State Center of Excellence in Materials Informatics at UB, and the Vice President for Research and Economic Development at UB.

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Be it with smartphones, laptops, or mainframes: The transmission, processing, and storage of information is currently based on a single class of material — as it was in the early days of computer science about 60 years ago. A new class of magnetic materials, however, could raise information technology to a new level. Antiferromagnetic insulators enable computing speeds that are a thousand times faster than conventional electronics, with significantly less heating. Components could be packed closer together and logic modules could thus become smaller, which has so far been limited due to the increased heating of current components.
Information transfer at room temperature
So far, the problem has been that the information transfer in antiferromagnetic insulators only worked at low temperatures. But who wants to put their smartphones in the freezer to be able to use it? Physicists at Johannes Gutenberg University Mainz (JGU) have now been able to eliminate this shortcoming, together with experimentalists from the CNRS/Thales lab, the CEA Grenoble, and the National High Field Laboratory in France as well as theorists from the Center for Quantum Spintronics (QuSpin) at the Norwegian University of Science and Technology. “We were able to transmit and process information in a standard antiferromagnetic insulator at room temperature — and to do so over long enough distances to enable information processing to occur,” said JGU scientist Andrew Ross. The researchers used iron oxide (α-Fe2O3), the main component of rust, as an antiferromagnetic insulator, because iron oxide is widespread and easy to manufacture.
The transfer of information in magnetic insulators is made possible by excitations of magnetic order known as magnons. These move as waves through magnetic materials, similar to how waves move across the water surface of a pond after a stone has been thrown into it. Previously, it was believed that these waves must have circular polarization in order to efficiently transmit information. In iron oxide, such circular polarization occurs only at low temperatures. However, the international research team was able to transmit magnons over exceptionally long distances even at room temperature. But how did that work? “We realized that in antiferromagnets with a single plane, two magnons with linear polarization can overlap and migrate together. They complement each other to form an approximately circular polarization,” explained Dr. Romain Lebrun, researcher at the joint CNRS/Thales laboratory in Paris who previously worked in Mainz. “The possibility of using iron oxide at room temperature makes it an ideal playground for the development of ultra-fast spintronic devices based on antiferromagnetic insulators.”
Extremely low attenuation allows for energy-efficient transmission
An important question in the process of information transfer is how quickly the information is lost when moving through magnetic materials. This can be recorded quantitatively with the value of the magnetic damping. “The iron oxide examined has one of the lowest magnetic attenuations that has ever been reported in magnetic materials,” explained Professor Mathias Kläui from the JGU Institute of Physics. “We anticipate that high magnetic field techniques will show that other antiferromagnetic materials have similarly low attenuation, which is crucial for the development of a new generation of spintronic devices. We are pursuing such low power magnetic technologies in a long-term collaboration with our colleagues at QuSpin in Norway and I am happy to see that another piece of exciting work as come out of this collaboration.”

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During the opening ceremonies of the 2018 Winter Olympics, held in PyeongChang, South Korea, Russian hackers launched a cyberattack that disrupted television and internet systems at the games. The incident was resolved quickly, but because Russia used North Korean IP addresses for the attack, the source of the disruption was unclear in the event’s immediate aftermath.
There is a lesson in that attack, and others like it, at a time when hostilities between countries increasingly occur online. In contrast to conventional national security thinking, such skirmishes call for a new strategic outlook, according to a new paper co-authored by an MIT professor.
The core of the matter involves deterrence and retaliation. In conventional warfare, deterrence usually consists of potential retaliatory military strikes against enemies. But in cybersecurity, this is more complicated. If identifying cyberattackers is difficult, then retaliating too quickly or too often, on the basis of limited information such as the location of certain IP addresses, can be counterproductive. Indeed, it can embolden other countries to launch their own attacks, by leading them to think they will not be blamed.
“If one country becomes more aggressive, then the equilibrium response is that all countries are going to end up becoming more aggressive,” says Alexander Wolitzky, an MIT economist who specializes in game theory. “If after every cyberattack my first instinct is to retaliate against Russia and China, this gives North Korea and Iran impunity to engage in cyberattacks.”
But Wolitzky and his colleagues do think there is a viable new approach, involving a more judicious and well-informed use of selective retaliation.
“Imperfect attribution makes deterrence multilateral,” Wolitzky says. “You have to think about everybody’s incentives together. Focusing your attention on the most likely culprits could be a big mistake.”
The paper, “Deterrence with Imperfect Attribution,” appears in the latest issue of the American Political Science Review. In addition to Wolitzky, the authors are Sandeep Baliga, the John L. and Helen Kellogg Professor of Managerial Economics and Decision Sciences at Northwestern University’s Kellogg School of Management; and Ethan Bueno de Mesquita, the Sydney Stein Professor and deputy dean of the Harris School of Public Policy at the University of Chicago.

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The study is a joint project, in which Baliga added to the research team by contacting Wolitzky, whose own work applies game theory to a wide variety of situations, including war, international affairs, network behavior, labor relations, and even technology adoption.
“In some sense this is a canonical kind of question for game theorists to think about,” Wolitzky says, noting that the development of game theory as an intellectual field stems from the study of nuclear deterrence during the Cold War. “We were interested in what’s different about cyberdeterrence, in contrast to conventional or nuclear deterrence. And of course there are a lot of differences, but one thing that we settled on pretty early is this attribution problem.” In their paper, the authors note that, as former U.S. Deputy Secretary of Defense William Lynn once put it, “Whereas a missile comes with a return address, a computer virus generally does not.”
In some cases, countries are not even aware of major cyberattacks against them; Iran only belatedly realized it had been attacked by the Stuxnet worm over a period of years, damaging centrifuges being used in the country’s nuclear weapons program.
In the paper, the scholars largely examined scenarios where countries are aware of cyberattacks against them but have imperfect information about the attacks and attackers. After modeling these events extensively, the researchers determined that the multilateral nature of cybersecurity today makes it markedly different than conventional security. There is a much higher chance in multilateral conditions that retaliation can backfire, generating additional attacks from multiple sources.
“You don’t necessarily want to commit to be more aggressive after every signal,” Wolitzky says.

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What does work, however, is simultaneously improving detection of attacks and gathering more information about the identity of the attackers, so that a country can pinpoint the other nations they could meaningfully retaliate against.
But even gathering more information to inform strategic decisions is a tricky process, as the scholars show. Detecting more attacks while being unable to identify the attackers does not clarify specific decisions, for instance. And gathering more information but having “too much certainty in attribution” can lead a country straight back into the problem of lashing out against some states, even as others are continuing to plan and commit attacks.
“The optimal doctrine in this case in some sense will commit you to retaliate more after the clearest signals, the most unambiguous signals,” Wolitzky says. “If you blindly commit yourself more to retaliate after every attack, you increase the risk you’re going to be retaliating after false alarms.”
Wolitzky points out that the paper’s model can apply to issues beyond cybersecurity. The problem of stopping pollution can have the same dynamics. If, for instance, numerous firms are polluting a river, singling just one out for punishment can embolden the others to continue.
Still, the authors do hope the paper will generate discussion in the foreign-policy community, with cyberattacks continuing to be a significant source of national security concern.
“People thought the possibility of failing to detect or attribute a cyberattack mattered, but there hadn’t [necessarily] been a recognition of the multilateral implications of this,” Wolitzky says. “I do think there is interest in thinking about the applications of that.” More

The team, led by Bristol researcher and Phasecraft co-founder, Dr. Ashley Montanaro, has discovered algorithms and analysis which significantly lessen the quantum hardware capability needed to solve problems which go beyond the realm of classical computing, even supercomputers.
In the paper, published in Physical Review B, the team demonstrates how optimised quantum algorithms can solve the notorious Fermi-Hubbard model on near-term hardware.
The Fermi-Hubbard model is of fundamental importance in condensed-matter physics as a model for strongly correlated materials and a route to understanding high-temperature superconductivity.
Finding the ground state of the Fermi-Hubbard model has been predicted to be one of the first applications of near-term quantum computers, and one that offers a pathway to understanding and developing novel materials.
Dr. Ashley Montanaro, research lead and cofounder of Phasecraft: “Quantum computing has critically important applications in materials science and other domains. Despite the major quantum hardware advances recently, we may still be several years from having the right software and hardware to solve meaningful problems with quantum computing. Our research focuses on algorithms and software optimisations to maximise the quantum hardware’s capacity, and bring quantum computing closer to reality.
“Near-term quantum hardware will have limited device and computation size. Phasecraft applied new theoretical ideas and numerical experiments to put together a very comprehensive study on different strategies for solving the Fermi-Hubbard model, zeroing in on strategies that are most likely to have the best results and impact in the near future.

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“The results suggest that optimising over quantum circuits with a gate depth substantially less than a thousand could be sufficient to solve instances of the Fermi-Hubbard model beyond the capacity of a supercomputer. This new research shows significant promise for the capabilities of near-term quantum devices, improving on previous research findings by around a factor of 10.”
Physical Review B, published by the American Physical Society, is the top specialist journal in condensed-matter physics. The peer-reviewed research paper was also chosen as the Editors’ Suggestion and to appear in Physics magazine.
Andrew Childs, Professor in the Department of Computer Science and Institute for Advanced Computer Studies at the University of Maryland: “The Fermi-Hubbard model is a major challenge in condensed-matter physics, and the Phasecraft team has made impressive steps in showing how quantum computers could solve it. Their work suggests that surprisingly low-depth circuits could provide useful information about this model, making it more accessible to realistic quantum hardware.”
Hartmut Neven, Head of Quantum Artificial Intelligence Lab, Google: “Sooner or later, quantum computing is coming. Developing the algorithms and technology to power the first commercial applications of early quantum computing hardware is the toughest challenge facing the field, which few are willing to take on. We are proud to be partners with Phasecraft, a team that are developing advances in quantum software that could shorten that timeframe by years.”
Phasecraft Founder Dr. Toby Cubitt: “At Phasecraft, our team of leading quantum theorists have been researching and applying quantum theory for decades, leading some of the top global academic teams and research in the field. Today, Ashley and his team have demonstrated ways to get closer to achieving new possibilities that exist just beyond today’s technological bounds.”
Phasecraft has closed a record seed round for a quantum company in the UK with £3.7m in funding from private-sector VC investors, led by LocalGlobe with Episode1 along with previous investors. Former Songkick founder Ian Hogarth has also joined as board chair for Phasecraft. Phasecraft previously raised a £750,000 pre-seed round led by UCL Technology Fund with Parkwalk Advisors and London Co-investment Fund and has earned several grants facilitated by InnovateUK. Between equity funding and research grants, Phasecraft has raised more than £5.5m.
Dr Toby Cubitt: “With new funding and support, we are able to continue our pioneering research and industry collaborations to develop the quantum computing industry and find useful applications faster.”

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Researchers at Pohang University of Science and Technology (POSTECH) and Seoul National University in South Korea have demonstrated a new way to enhance the energy efficiency of a non-volatile magnetic memory device called SOT-MRAM. Published in Advanced Materials, this finding opens up a new window of exciting opportunities for future energy-efficient magnetic memories based on spintronics.
In modern computers, the random access memory (RAM) is used to store information. The SOT-MRAM (spin-orbit torque magnetic RAM) is one of the leading candidates for the next-generation memory technologies that aim to surpass the performance of various existing RAMs. The SOT-MRAM may operate faster than the fastest existing RAM (SRAM) and maintain information even after the electric energy supply is powered off whereas all fast RAMs existing today lose information as soon as the energy supply is powered off. The present level of the SOT-MRAM technology falls short of being satisfactory, however, due to its high energy demand; it requires large energy supply (or large current) to write information. Lowering the energy demand and enhancing the energy efficiency is an outstanding problem for the SOT-MRAM.
In the SOT-MRAM, magnetization directions of tiny magnets store information and writing amounts to change the magnetization directions to desired directions. The magnetization direction change is achieved by a special physics phenomenon called SOT that modifies the magnetization direction when a current is applied. To enhance the energy efficiency, soft magnets are ideal material choice for the tiny magnets since their magnetization directions can be easily alterned by a small current. Soft magnets are bad choice for the safe storage of information since their magnetization direction may be altered even when not intended — due to thermal noise or other noise. For this reason, most attempts to build the SOT-MRAM adopt hard magnets, because they magnetize very strongly and their magnetization direction is not easily altered by noise. But this material choice inevitably makes the energy efficiency of the SOT-MRAM poor.
A joint research team led by Professor Hyun-Woo Lee in the Department of Physics at POSTECH and Professor Je-Geun Park in the Department of Physics at Seoul National University (former associate director of the Center for Correlated Electron Systems within the Institute for Basic Science in Korea), demonstrated a way to enhance the energy efficiency without sacrificing the demand for safe storage. They reported that ultrathin iron germanium telluride (Fe3GeTe2, FGT) — a ferromagnetic material with special geometrical symmetry and quantum properties — switches from a hard magnet to a soft magnet when a small current is applied. Thus when information writing is not intended, the material remains a hard magnet, which is good for the safe storage, and only when writing is intended, the material switches to a soft magnet, allowing for enhanced energy efficiency.
“Intriguing properties of layered materials never cease to amaze me: the current through FGT induces a highly unusual type of spin-orbit torque (SOT), which modifies the energy profile of this material to switch it from a hard magnet to a soft magnet. This is in clear contrast to SOT produced by other materials, which may change the magnetization direction but cannot switch a hard magnet to a soft magnet,” explains Professor Lee.
Experiments by Professor Park’s group revealed that this FGT-based magnetic memory device is highly energy-efficient. In particular, the measured magnitude of SOT per applied current density is two orders of magnitude larger than the values reported previously for other candidate materials for the SOT-MRAM.
“Controlling magnetic states with a small current is essential for the next-generation of energy-efficient devices. These will be able to store greater amounts of data and enable faster data access than today’s electronic memories, while consuming less energy,” notes Dr. Kaixuan Zhang who is a team leader in Professor Park’s group, interested in studying the application of correlated quantum physics in spintronic devices.
“Our findings open up a fascinating avenue of electrical modulation and spintronic applications using 2D layered magnetic materials,” closed Professor Lee.

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Researchers at Hokkaido University and Amoeba Energy in Japan have, inspired by the efficient foraging behavior of a single-celled amoeba, developed an analog computer for finding a reliable and swift solution to the traveling salesman problem — a representative combinatorial optimization problem.
Many real-world application tasks such as planning and scheduling in logistics and automation are mathematically formulated as combinatorial optimization problems. Conventional digital computers, including supercomputers, are inadequate to solve these complex problems in practically permissible time as the number of candidate solutions they need to evaluate increases exponentially with the problem size — also known as combinatorial explosion. Thus new computers called “Ising machines,” including “quantum annealers,” have been actively developed in recent years. These machines, however, require complicated pre-processing to convert each task to the form they can handle and have a risk of presenting illegal solutions that do not meet some constraints and requests, resulting in major obstacles to the practical applications.
These obstacles can be avoided using the newly developed “electronic amoeba,” an analog computer inspired by a single-celled amoeboid organism. The amoeba is known to maximize nutrient acquisition efficiently by deforming its body. It has shown to find an approximate solution to the traveling salesman problem (TSP), i.e., given a map of a certain number of cities, the problem is to find the shortest route for visiting each city exactly once and returning to the starting city. This finding inspired Professor Seiya Kasai at Hokkaido University to mimic the dynamics of the amoeba electronically using an analog circuit, as described in the journal Scientific Reports. “The amoeba core searches for a solution under the electronic environment where resistance values at intersections of crossbars represent constraints and requests of the TSP,” says Kasai. Using the crossbars, the city layout can be easily altered by updating the resistance values without complicated pre-processing.
Kenta Saito, a PhD student in Kasai’s lab, fabricated the circuit on a breadboard and succeeded in finding the shortest route for the 4-city TSP. He evaluated the performance for larger-sized problems using a circuit simulator. Then the circuit reliably found a high-quality legal solution with a significantly shorter route length than the average length obtained by the random sampling. Moreover, the time required to find a high-quality legal solution grew only linearly to the numbers of cities. Comparing the search time with a representative TSP algorithm “2-opt,” the electronic amoeba becomes more advantageous as the number of cities increases. “The analog circuit reproduces well the unique and efficient optimization capability of the amoeba, which the organism has acquired through natural selection,” says Kasai.
“As the analog computer consists of a simple and compact circuit, it can tackle many real-world problems in which inputs, constraints, and requests dynamically change and can be embedded into IoT devices as a power-saving microchip,” says Masashi Aono who leads Amoeba Energy to promote the practical use of the amoeba-inspired computers.
This is a Joint Release between Hokkaido University and Amoeba Energy Co., Ltd.

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Robotic animals could be the ‘pawfect’ replacement for our real-life furry friends, a new study published today by the University of Portsmouth has found.
Animals, especially dogs, can have therapeutic benefits for children and young people. A new paper, published in The International Journal of Social Robotics, has found that the robotic animal, ‘MiRo-E’, can be just as effective and may even be a better alternative.
Dr Leanne Proops from the Department of Psychology, who supervised the study said: “We know that real dogs can provide calming and enjoyable interactions for children — increasing their feelings of wellbeing, improving motivation and reducing stress.
“This preliminary study has found that biomimetic robots — robots that mimic animal behaviours — may be a suitable replacement in certain situations and there are some benefits to using them over a real dog.”
Dogs are the most commonly used animals for therapy because of their training potential and generally social nature. However, there are concerns about using them in a setting with children because of the risk of triggering allergies or transmitting disease, and some people do not like dogs, so may not be comfortable in the presence of a real therapy dog.
Olivia Barber, who owns a therapy dog herself, and is first author of the paper, said: “Although lots of people in schools and hospitals benefit greatly from receiving visits from a therapy dog, we have to be mindful of the welfare of the therapy dog. Visits can be stressful and incredibly tiring for therapy dogs, meaning that we should be exploring whether using a robotic animal is feasible.”
There are lots of positives to using a robotic animal over a therapy dog. They can be thoroughly cleaned and can work for longer periods of time. They can also be incredibly lifelike, mirroring the movements and behaviour of a real animal, such as wagging their tails to show excitement, expressing “emotions” through sounds and colour, turning their ears towards sounds and even going to sleep.

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The researchers used real dogs and a biomimetic robot in a mainstream secondary school in West Sussex to interact with 34 children aged 11-12.
The two real-life therapy dogs were a three-year-old Jack Russell crossed with a Poodle and a 12-year-old Labrador-retriever from the charity Pets as Therapy. The robot was a MiRo-E biomimetic robot developed by Consequential Robotics.
The children were asked to complete a questionnaire about their beliefs and attitudes towards dogs and robots, before they took part in two separate free-play sessions, one with a real-life dog and one with a robot.
The researchers found the children spent a similar amount of time stroking both the real-life dog and the robot, but they spent more time interacting with the robot.
Despite the children reporting they significantly preferred the session with the living dog, overall enjoyment was high and they actually expressed more positive emotions following interaction with the robot. The more the children attributed mental states and sentience to the dog and robot, the more they enjoyed the sessions.
Dr Proops said: “This is a small-scale study, but the results show that interactive robotic animals could be used as a good comparison to live dogs in research, and a useful alternative to traditional animal therapy.”

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Although robotics has reshaped and even redefined many industrial sectors, there still exists a gap between machines and humans in fields such as health and elderly care. For robots to safely manipulate or interact with fragile objects and living organisms, new strategies to enhance their perception while making their parts softer are needed. In fact, building a safe and dexterous robotic gripper with human-like capabilities is currently one of the most important goals in robotics.
One of the main challenges in the design of soft robotic grippers is integrating traditional sensors onto the robot’s fingers. Ideally, a soft gripper should have what’s known as proprioception — a sense of its own movements and position — to be able to safely execute varied tasks. However, traditional sensors are rigid and compromise the mechanical characteristics of the soft parts. Moreover, existing soft grippers are usually designed with a single type of proprioceptive sensation; either pressure or finger curvature.
To overcome these limitations, scientists at Ritsumeikan University, Japan, have been working on novel soft gripper designs under the lead of Associate Professor Mengying Xie. In their latest study published in Nano Energy, they successfully used multimaterial 3D printing technology to fabricate soft robotic fingers with a built-in proprioception sensor. Their design strategy offers numerous advantages and represents a large step toward safer and more capable soft robots.
The soft finger has a reinforced inflation chamber that makes it bend in a highly controllable way according to the input air pressure. In addition, the stiffness of the finger is also tunable by creating a vacuum in a separate chamber. This was achieved through a mechanism called vacuum jamming, by which multiple stacked layers of a bendable material can be made rigid by sucking out the air between them. Both functions combined enable a three-finger robotic gripper to properly grasp and maintain hold of any object by ensuring the necessary force is applied.
Most notable, however, is that a single piezoelectric layer was included among the vacuum jamming layers as a sensor. The piezoelectric effect produces a voltage difference when the material is under pressure. The scientists leveraged this phenomenon as a sensing mechanism for the robotic finger, providing a simple way to sense both its curvature and initial stiffness (prior to vacuum adjustment). They further enhanced the finger’s sensitivity by including a microstructured layer among the jamming layers to improve the distribution of pressure on the piezoelectric material.
The use of multimaterial 3D printing, a simple and fast prototyping process, allowed the researchers to easily integrate the sensing and stiffness-tuning mechanisms into the design of the robotic finger itself. “Our work suggests a way of designing sensors that contribute not only as sensing elements for robotic applications, but also as active functional materials to provide better control of the whole system without compromising its dynamic behavior,” says Prof Xie. Another remarkable feature of their design is that the sensor is self-powered by the piezoelectric effect, meaning that it requires no energy supply — essential for low-power applications.
Overall, this exciting new study will help future researchers find new ways of improving how soft grippers interact with and sense the objects being manipulated. In turn, this will greatly expand the uses of robots, as Prof Xie indicates: “Self-powered built-in sensors will not only allow robots to safely interact with humans and their environment, but also eliminate the barriers to robotic applications that currently rely on powered sensors to monitor conditions.”
Let’s hope this technology is further developed so that our mechanical friends can soon join us in many more human activities!

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