magnetism (4)

Steve Austin's Beads...


Magnetic prosthetic: A magnetic sensing array enables a new tissue tracking strategy that could offer advanced motion control in artificial limbs. (Courtesy: MIT Media Lab/Cameron Taylor/Vessel Studios)

Topics: Biotechnology, Magnetism, Materials Science, Medicine, Nanotechnology, Robotics

Cultural reference: The Six Million Dollar Man, NBC

In recent years, health and fitness wearables have gained popularity as platforms to wirelessly track daily physical activities, by counting steps, for example, or recording heartbeats directly from the wrist. To achieve this, inertial sensors in contact with the skin capture the relevant motion and physiological signals originating from the body.

As wearable technology evolves, researchers strive to understand not just how to track the body’s dynamic signals, but also how to simulate them to control artificial limbs. This new level of motion control requires a detailed understanding of what is happening beneath the skin, specifically, the motion of the muscles.

Skeletal muscles are responsible for almost all movement of the human body. When muscle fibers contract, the exerted forces travel through the tendons, pull the bones, and ultimately produce motion. To track and use these muscle contractions in real-time and with high signal quality, engineers at the Massachusetts Institute of Technology (MIT) employed low-frequency magnetic fields – which pass undisturbed through body tissues – to provide accurate and real-time transcutaneous sensing of muscle motion. They describe their technique in Science Robotics.

Magnetic beads inside the body could improve control of bionic limbs, Raudel Avila is a student contributor to Physics World

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Virgin Hyperloop...


Topics: Economics, Futurism, Magnetism, Transportation

In the desert just north of Las Vegas, a long white metal tube sits at the base of the mountains, promising to one day revolutionize travel.

That is where Virgin Hyperloop, whose partners include Richard Branson's Virgin Group, is developing the technology for passenger pods that will hurtle at speeds of up to 750 miles an hour (1,200 kph) through almost air-free vacuum tunnels using magnetic levitation.

"It will feel like an aircraft at take-off and once you're at speed," said co-founder and Chief Executive Josh Giegel, who gave Reuters an exclusive tour of the pod used in its November test run, where it was propelled along a 500 meter (1,640 ft.) tunnel.

"You won't even have turbulence because our system is basically completely able to react to all that turbulence. Think noise-canceling but bump-canceling, if you will."

Virgin Hyperloop shows off the future: mass transport in floating magnetic pods, Reuters

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Kondo Mimic...


Illustration showing the atomic tip of a scanning tunneling microscope while probing a metal surface with a cobalt atom positioned on top. A characteristic dip in the measurement results is found on surfaces made of copper as well as silver and gold. Courtesy: Forschungszentrum Jülich

Topics: Magnetism, Materials Science, Nanotechnology

A new type of quasiparticle – dubbed the “spinaron” by the scientists who discovered it – could be responsible for a magnetic phenomenon that is usually attributed to the Kondo effect. The research, which was carried out by Samir Lounis and colleagues at Germany’s Forschungszentrum Jülich, casts doubt on current theories of the Kondo effect and could have implications for data storage and processing based on structures such as quantum dots.

The electrical resistance of most metals decreases as the temperature drops. Metals containing magnetic impurities, however, behave differently. Below a certain threshold temperature, their electrical resistance increases rapidly and continues to increase as the temperature drops further. First spotted in the 1930s, this phenomenon became known as the Kondo effect after the Japanese theoretical physicist Jun Kondo published an explanation for it in 1964.

New quasiparticle may mimic Kondo-effect signal, Isabelle Dumé, Physics World

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Uranium Telluride...

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Topics: Atomic Physics, Magnetism, Superconductors

Superconductivity and magnetism don’t usually mix. When a superconductor is placed in a magnetic field, it expels the field from its bulk through the Meissner effect; a strong enough field destroys the superconducting state entirely. In the vast majority of superconductors, electrons form spin-singlet pairs, with s– or d-wave symmetry, that are twisted apart by the field. Even the rare p-wave, spin-triplet superconductors (such as strontium ruthenate; see Physics Today, December 2006, page 23) are limited in how strong a magnetic field they can tolerate.
Web Elements: Uranium Tritelluride

Last year the list of unusual superconductors grew by one, when Nicholas Butch and colleagues at NIST and the University of Maryland discovered spin-triplet superconductivity in uranium telluride, or UTe2. (The paper reporting their results, although submitted in October 2018, wasn’t published until this August; in the intervening time, the discovery was confirmed by a team of researchers at Tohoku University in Japan and Grenoble Alps University in France.)


Exotic superconducting state lurks at an astonishingly high magnetic field
Johanna L. Miller, Physics Today

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