Mind-controlled arm prostheses that 'feel' are now a part of everyday life
Date: April 30, 2020
Source: Chalmers University of Technology
For the first time, people with arm amputations can experience sensations of touch in a mind-controlled arm prosthesis that they use in everyday life. A study reports on three Swedish patients who have lived, for several years, with this new technology -- one of the world's most integrated interfaces between human and machine.
For the first time, people with arm amputations can experience sensations of touch in a mind-controlled arm prosthesis that they use in everyday life. A study in the New England Journal of Medicine reports on three Swedish patients who have lived, for several years, with this new technology -- one of the world's most integrated interfaces between human and machine.
The advance is unique: the patients have used a mind-controlled prosthesis in their everyday life for up to seven years. For the last few years, they have also lived with a new function -- sensations of touch in the prosthetic hand. This is a new concept for artificial limbs, which are called neuromusculoskeletal prostheses -- as they are connected to the user's nerves, muscles, and skeleton.
The research was led by Max Ortiz Catalan, Associate Professor at Chalmers University of Technology, in collaboration with Sahlgrenska University Hospital, University of Gothenburg, and Integrum AB, all in Gothenburg, Sweden. Researchers at Medical University of Vienna in Austria and the Massachusetts Institute of Technology in the USA were also involved.
"Our study shows that a prosthetic hand, attached to the bone and controlled by electrodes implanted in nerves and muscles, can operate much more precisely than conventional prosthetic hands. We further improved the use of the prosthesis by integrating tactile sensory feedback that the patients use to mediate how hard to grab or squeeze an object. Over time, the ability of the patients to discern smaller changes in the intensity of sensations has improved," says Max Ortiz Catalan.
"The most important contribution of this study was to demonstrate that this new type of prosthesis is a clinically viable replacement for a lost arm. No matter how sophisticated a neural interface becomes, it can only deliver real benefit to patients if the connection between the patient and the prosthesis is safe and reliable in the long term. Our results are the product of many years of work, and now we can finally present the first bionic arm prosthesis that can be reliably controlled using implanted electrodes, while also conveying sensations to the user in everyday life," continues Max Ortiz Catalan.
Since receiving their prostheses, the patients have used them daily in all their professional and personal activities.
The new concept of a neuromusculoskeletal prosthesis is unique in that it delivers several different features which have not been presented together in any other prosthetic technology in the world:
• It has a direct connection to a person's nerves, muscles, and skeleton.
• It is mind-controlled and delivers sensations that are perceived by the user as arising from the missing hand.
• It is self-contained; all electronics needed are contained within the prosthesis, so patients do not need to carry additional equipment or batteries.
• It is safe and stable in the long term; the technology has been used without interruption by patients during their everyday activities, without supervision from the researchers, and it is not restricted to confined or controlled environments.
The newest part of the technology, the sensation of touch, is possible through stimulation of the nerves that used to be connected to the biological hand before the amputation. Force sensors located in the thumb of the prosthesis measure contact and pressure applied to an object while grasping. This information is transmitted to the patients' nerves leading to their brains. Patients can thus feel when they are touching an object, its characteristics, and how hard they are pressing it, which is crucial for imitating a biological hand.
"Currently, the sensors are not the obstacle for restoring sensation," says Max Ortiz Catalan. "The challenge is creating neural interfaces that can seamlessly transmit large amounts of artificially collected information to the nervous system, in a way that the user can experience sensations naturally and effortlessly."
The implantation of this new technology took place at Sahlgrenska University Hospital, led by Professor Rickard Brånemark and Doctor Paolo Sassu. Over a million people worldwide suffer from limb loss, and the end goal for the research team, in collaboration with Integrum AB, is to develop a widely available product suitable for as many of these people as possible.
"Right now, patients in Sweden are participating in the clinical validation of this new prosthetic technology for arm amputation," says Max Ortiz Catalan. "We expect this system to become available outside Sweden within a couple of years, and we are also making considerable progress with a similar technology for leg prostheses, which we plan to implant in a first patient later this year."
How the technology works:
The implant system for the arm prosthesis is called e-OPRA and is based on the OPRA implant system created by Integrum AB. The implant system anchors the prosthesis to the skeleton in the stump of the amputated limb, through a process called osseointegration (osseo = bone). Electrodes are implanted in muscles and nerves inside the amputation stump, and the e-OPRA system sends signals in both directions between the prosthesis and the brain, just like in a biological arm.
The prosthesis is mind-controlled, via the electrical muscle and nerve signals sent through the arm stump and captured by the electrodes. The signals are passed into the implant, which goes through the skin and connects to the prosthesis. The signals are then interpreted by an embedded control system developed by the researchers. The control system is small enough to fit inside the prosthesis and it processes the signals using sophisticated artificial intelligence algorithms, resulting in control signals for the prosthetic hand's movements.
The touch sensations arise from force sensors in the prosthetic thumb. The signals from the sensors are converted by the control system in the prosthesis into electrical signals which are sent to stimulate a nerve in the arm stump. The nerve leads to the brain, which then perceives the pressure levels against the hand.
The neuromusculoskeletal implant can connect to any commercially available arm prosthesis, allowing them to operate more effectively.
How the artificial sensation is experienced:
People who lose an arm or leg often experience phantom sensations, as if the missing body part remains although not physically present. When the force sensors in the prosthetic thumb react, the patients in the study feel that the sensation comes from their phantom hand. Precisely where on the phantom hand varies between patients, depending on which nerves in the stump receive the signals. The lowest level of pressure can be compared to touching the skin with the tip of a pencil. As the pressure increases, the feeling becomes stronger and increasingly 'electric'.
The current study dealt with patients with above-elbow amputations, and this technology is close to becoming a finished product. The research team is working in parallel with a new system for amputations below the elbow. In those cases, instead of one large bone (humerus), there are two smaller bones (radius and ulna) to which the implant needs to be anchored. The group is also working on adapting the system for leg prostheses.
In addition to applications within prosthetics, the permanent interface between human and machine provides entirely new opportunities for scientific research into how the human muscular and nervous systems work.
Associate Professor Max Ortiz Catalan heads the Biomechatronics and Neurorehabilitation Laboratory at Chalmers University of Technology and is currently establishing the new Center for Bionics and Pain Research at Sahlgrenska University Hospital, in close collaboration with Chalmers and the University of Gothenburg, where this work will be further developed and clinically implemented.
The research has been funded by the Promobilia Foundation, the IngaBritt and Arne Lundbergs Research Foundation, Region Västra Götaland (ALF grants), Vinnova, the Swedish Research Council, and the European Research Council.
Materials provided by Chalmers University of Technology. Original written by Johanna Wilde. Note: Content may be edited for style and length.
1. Max Ortiz-Catalan, Enzo Mastinu, Paolo Sassu, Oskar Aszmann, Rickard Brånemark. Self-Contained Neuromusculoskeletal Arm Prostheses. New England Journal of Medicine, 2020; 382 (18): 1732 DOI: 10.1056/NEJMoa1917537
A newly-created mouse-human embryo contains up to 4% human cells — the most human cells yet of any chimera, or an organism made of two different sets of DNA.
Surprisingly, those human cells could learn from the mouse cells and develop faster — at the pace of a mouse embryo rather than a more slowly developing human embryo. That finding was "very serendipitous… We did not really foresee that," said senior author Jian Feng, a professor in the department of physiology and biophysics at the State University of New York at Buffalo.
Successfully growing human cells in mouse embryos might one day help scientists understand the growth and aging process of our bodies and how diseases such as COVID-19 damage cells — and could eventually even serve as a scaffold to grow organs for transplantation, Feng said.
Feng and his team tackled a long-standing issue in creating such chimeras: that in order for human embryonic stem cells and mouse embryonic stem cells to chat and mingle, they needed to be in the same state of development. Embryonic stem cells are pluripotent, meaning they can develop into any type of cell in the body.
But "the human embryonic stem cell looks and behaves very differently from the mouse embryonic stem cell," so past attempts to get them to comingle have all failed, Feng told Live Science. At first, researchers thought the failures were due to some kind of species barrier; but after many years of study, they realized that it wasn't a species issue, but rather a maturity one.
The human stem cells were in a later stage of development called a "primed" state, which normally occurs only after the human embryo has already been implanted in the uterine wall. In contrast, the mouse stem cells were in a more "naive" state, which normally occurs when the mouse embryo is still floating around in the fallopian tubes. In the past, researchers weren't able to convert human cells back to this naive state, Feng said.
Human cells (green) that developed in a mouse embryo's eye (blue). (Image credit: Jian Feng)
Turning cells naive
In their experiments, Feng and his team were inspired by a process called "embryonic diapause" that occurs in hundreds of mammals from bears to mice: When there's some sort of hardship such as a famine or shortage of water, some animals' embryos can remain in the naive state inside a mother's fallopian tubes for months — and sometimes over a year — for the environment to become more suitable, Feng said.
It's not clear what triggers the embryos to pause in this state, but a protein called mTOR seems to be a sensor that detects when conditions are bad, he said. Feng and his team figured out that they could target this protein inside human stem cells to make the cells think that they were experiencing famine, and needed to jump to a more naive state where they could conserve energy, Feng said.
The protein mTOR normally promotes the production of proteins and other molecules to support cell growth and proliferation, so by inhibiting it, Feng and his team "shocked" the human cells into changing their metabolism and gene expression. "So it behaves pretty much like the mouse cell," Feng said. What resulted was a naive set of human stem cells that could be cultured together with mouse stem cells and "intermingle very nicely," Feng said. The researchers then injected 10 to 12 of these naive human stem cells into mouse embryos.
In most of the mouse embryos, the naive human stem cells successfully developed into mature human cells in all three germ layers: the ectoderm, or the primary cell layers that develop when the embryo is growing and which later develop to form hair, nails, the epidermis and nerve tissue; the mesoderm, or the cells that make up the organs; and the endoderm, or the inner lining of organs. But no human cells spilled over into germline tissue, which develops into egg and sperm cells.
These germ layers then developed into more differentiated cells, and when the researchers stopped their experiment on the 17th day, 14 embryos were between 0.1% and 4% human (some had less human cells and some had more), with human cells found through the embryo, including in the liver, heart, retina and red blood cells.
But what was really "surprising" was the speed at which the human cells developed, Feng said. For example, the embryos were able to generate human red blood cells in 17 days, compared to the roughly 56 days red blood cells take to develop in a growing human embryo. Similarly, human eye cells don't develop until much later on in the embryo, whereas within 17 days, human eye cells including photo receptors formed in the chimera. Basically, the human cells "assumed the clock of the mouse embryo," Feng said. Previously, scientists thought this accelerated development was impossible because the tempo of human cell development was always thought to be "kind of immutable," he added.
Organ transplants and ethical dilemmas
This paper identifies a "novel way" of turning primed human pluripotent stem cells into a naive state, said Ronald Parchem, an assistant professor in the Stem Cells and Regenerative Medicine Center at Baylor College of Medicine in Texas, who was not a part of the study. But "the level of chimerism is low in this study," compared to another study that developed chimeras with up to 20% human cells per embryo, he said. That study, however, was published to the preprint database Biorxiv on May 24,and hasn't yet been peer-reviewed. "Together, these studies provide insight into capturing pluripotent states in vitro and highlight the barriers preventing successful cross-species chimerism," Parchem said. "Identifying ways to overcome these barriers has the potential to improve regenerative medicine."
These findings might "stimulate research" in the fundamental understanding of human development, especially how time is measured by biological systems, Feng said. Such chimeras could help scientists understand human diseases. For example, researchers might one day be able to regenerate human blood in a mouse model and study diseases such as malaria. Or if you can create human lung cells, or epithelial cells that line the respiratory tract, that mouse can become a "model system" for studying diseases like COVID-19, Feng said. In other words, mice with human cells can be infected with COVID-19 to understand how the virus attacks the body.
The most cited potential application of such chimeras is organ growth. But this likely won't happen in mice but much larger animals such as pigs, he said. Of course, these applications raise ethical issues, he added. One such ethical consideration is that chimeras blur the lines between species and that makes it difficult to determine the morality or the consciousness that those animals possess. For example, chimeras used in animal testing could be given too many human characteristics and have a similar moral status or consciousness to us, according to a previous Live Science report.
Feng said that much discussion needs to take place before such applications can be considered.
"This field requires much more exploration before this becomes a reality," said Carol Ware, the associate director at the University of Washington's Institute for Stem Cell and Regenerative Medicine, who was also not a part of the study. "A couple of the primary hurdles at this point are determining the host species for these human cells," and public acceptance in the work, she added.
"At this point, it would seem that the speed with which this clinical opportunity will become a reality will not be hindered by the ability to grow human organs," she added. "I would have liked to see," what happens when mTOR is taken away inside the lab dish and these naive human cells are allowed to advance again, particularly to see if some key cellular processes resume again, she added.
The findings were published in the journal Science Advances on May 13.
Boys & Girls, check out this el-cheapo Geiger-Mueller tube counter, for monitoring the radiation environment...never know when ET will be hanging around over your house looking a bit like Rutledge-pseudo-stars!
Just the counter board, also requires a tube, which is listed further down the page...
Once again, physicists have confirmed one of Albert Einstein's core ideas about gravity — this time with the help of a neutron star flashing across space.
The new work makes an old idea even more certain: that heavy and light objects fall at the same rate. Einstein wasn't the first person to realize this; there are contested accounts of Galileo Galilei demonstrating the principle by dropping weights off the Tower of Pisa in the 16th century. And suggestions of the idea appear in the work of the 12th-century philosopher Abu'l-Barakāt al-Baghdādī. This concept eventually made its way into Isaac Newton's model of physics, and then Einstein's theory of general relativity as the gravitational "strong equivalence principle" (SEP). This new experiment demonstrates the truth of the SEP, using a falling neutron star, with more precision than ever.
The SEP has appeared to be true for a long time. You might have seen this video of Apollo astronauts dropping a feather and a hammer in the vacuum of the moon, showing that they fall at the same rate in lunar gravity:
But small tests in the relatively weak gravitational fields of Earth, the moon or the sun don't really put the SEP through its paces, according to Sharon Morsink, an astrophysicist at the University of Alberta in Canada, who wasn't involved in the new study.
"At some level, the majority of physicists believe that Einstein's theory of gravity, called general relativity, is correct. However, that belief is mainly based on observations of phenomena taking place in regions of space with weak gravity, while Einstein's theory of gravity is meant to explain phenomena taking place near really strong gravitational fields," Morsink told Live Science. "Neutron stars and black holes are the objects that have the strongest known gravitational fields, so any test of gravity that involves these objects really test the heart of Einstein's gravity theory."
Neutron stars are the collapsed cores of dead stars. Super dense, but not dense enough to form black holes, they can pack masses greater than that of our sun into whirling spheres just a few miles wide.
The researchers focused on a type of neutron star called a pulsar, which from Earth's perspective seems to flash as it spins. That flashing is a result of a bright spot on the star's surface whirling in and out of view, 366 times per second. This spinning is regular enough to keep time by.
This pulsar, known as J0337+1715, is special even among pulsars: It's locked in a tight binary orbit with a white dwarf star. The two stars orbit each other as they circle a third star, also a white dwarf, just like Earth and the moon do as they circle the sun.
(Researchers have already shown that the SEP is true for orbits like this in our solar system: Earth and the moon are affected to exactly the same degree by the sun's gravity, measurements suggest.)
The precise timekeeping of J0337+1715, combined with its relationship to those two gravity fields created by the two white dwarf stars, offers astronomers a unique opportunity to test the principle.
The pulsar is much heavier than the other two stars in the system. But the pulsar still falls toward each of them a little bit as they fall toward the pulsar's larger mass. (The same thing happens with you and Earth. When you jump, you fall back toward the planet very quickly. But the planet falls toward you as well — very slowly, due to your own low gravity, but at the exact same rate as a feather or a hammer would if you ignore air resistance.) And because J0337+1715 is such a precise timekeeper, astronomers on Earth can track how the gravitational fields of the two stars affect the pulsar's period.
To do so, the astronomers carefully timed the arrival of light from J0337+1715 using large radio telescopes, in particular the Nançay Radio Observatory in France. As the star moved around each of its neighbors — one in a quick little orbit and one in a longer, slower orbit — the pulsar got closer and farther from Earth. As the neutron star moved farther away from Earth, the light from its pulses had to travel longer distances to reach the telescope. So, to a tiny degree, the gaps between the pulses seemed to get longer.
As the pulsar swung back toward Earth, the gaps between the pulses got shorter. That allowed physicists to build a robust model of the neutron star's movement through space, explaining precisely how it interacted with the gravity fields of its neighbors. Their work built on a technique used in an earlier paper, published in the journal Nature in 2018, to study the same system.
The new paper, published online June 10 in the journal Astronomy and Astrophysics, showed that the objects in this system behaved as Einstein's theory predicts — or at least didn't differ from Einstein's predictions by more than 1.8 parts per million. That's the absolute limit of the precision of their telescope data analysis. They reported 95% confidence in their findings.
Morsink, who uses X-ray data to study the mass, widths, and surface patterns of neutron stars, said that this confirmation isn't surprising, but it is important for her research.
"In that work, we have to assume that Einstein's theory of gravity is correct, since the data analysis is already very complex," Morsink told Live Science in an in an email. "So tests of Einstein's gravity using neutron stars really make me feel better about our assumption that Einstein's theory describes the gravity of a neutron star correctly!"
Without understanding the SEP, Einstein would never have been able to develop his ideas of relativity. In an insight he described as "the most fortunate thought in my life," he recognized that objects in free fall don't feel the gravitational fields tugging on them.
(This is why astronauts in orbit around the Earth float. In constant free fall, they don't experience the gravitational field that holds them in orbit. Without windows, they wouldn't know Earth was there at all.)
Most of Einstein's key insights about the universe begin with the universality of free fall. So, in this way, the cornerstone of general relativity has been made that much stronger.
CERN makes bold push to build €21-billion super-collider
19 JUNE 2020
European particle-physics lab will pursue a 100-kilometre machine to uncover the Higgs boson’s secrets — but it doesn’t yet have the funds.
The Future Circular Collider (FCC) is a proposed particle accelerator that would follow the Large Hadron Collider at CERN.Credit: Polar Media
CERN has taken a major step towards building a 100-kilometre circular super-collider to push the frontier of high-energy physics.
The decision was unanimously endorsed by the CERN Council on 19 June, following the plan’s approval by an independent panel in March. Europe’s preeminent particle-physics organization will need global help to fund the project, which is expected to cost at least €21 billion and would be a follow-up to the lab’s famed Large Hadron Collider. The new machine would collide electrons with their antimatter partners, positrons, by the middle of the century. The design — to be built in an underground tunnel near CERN’s location in Geneva, Switzerland — will enable physicists to study the properties of the Higgs boson and, later, to host an even more powerful machine that will collide protons and last well into the second half of the century.
The approval is not yet a final go-ahead. But it means CERN can now put substantial effort into designing a collider and researching its feasibility, while pushing to the backburner research and development efforts for alternative designs for LHC follow-ups, such as a linear eletron-positron collider or one that would accelerate muons. “I think it’s a historic day for CERN and particle physics, in Europe and beyond,” CERN director-general Fabiola Gianotti told the council after the vote.
This is “clearly a branching point” for the lab, says former CERN director-general Chris Llewellyn-Smith. Until today, several other options were on the table for a next-generation collider, but the CERN Council has now made an unambiguous, unanimous statement. “This is a major step, to get the countries of Europe to say ‘Yes, this is what we would like to happen’,” says Llewellyn-Smith, who is a physicist at the University of Oxford, UK.
The decision comes in a document approved today, called European Strategy for Particle Physics Update. It outlines on two stages of development. First, CERN would build an electron-positron collider with collision energies tuned to maximize the production of Higgs bosons and understand their properties in detail.
Later in the century, the first machine would be dismantled and replaced by a proton-proton smasher. That would reach collision energies of 100 teraelectronvolts (TeV), compared with the 16 TeV of the LHC, which also collides protons and is currently the most powerful accelerator in the world. Its goal would be to search for new particles or forces of nature and to extend or replace the current standard model of particle physics. Much of the technology that the final machine will require has yet to be developed, and will be the subject of intensive study in coming decades.
“This is a very ambitious strategy, which outlines a bright future for Europe and for CERN with a prudent, step-wise approach,” said Gianotti.
“I think certainly this is the right direction to pursue,” says Yifang Wang, who heads the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences in Beijing. CERN’s proposed new machine is similar in concept to a proposal that Wang has spearheaded for a Chinese collider, in the wake of the LHC’s discovery of the Higgs boson in 2012. Like CERN’s now-official strategy, Wang’s proposal also included the possibility to host a proton collider in a second stage, following the LHC’s model (the 27-kilometre LHC ring occupies the tunnel that housed CERN’s Large Electron-Positron Collider in the 1990s). CERN’s decision “is confirmation that our choice was the right one”, Wang says.
While fully endorsing a CERN circular collider, the strategy also calls for the organization to explore participation in a separate International Linear Collider, an older idea that has been kept alive by physicists in Japan. Hitoshi Yamamoto, a physicist at Tohoku University in Sendai, Japan, says the endorsement is encouraging. “I believe that the conditions for ILC to move to the next step in Japan and also globally are now firmly in place.”
CERN’s strategy envisions 2038 as the beginning of construction for the new, 100-kilometer tunnel and the electron-positron collider. Until then, the lab will continue to operate an upgraded version of its current collider called High Luminosity LHC, which is currently under construction.
But before CERN can start building its new machine, it will have to seek new funding beyond the regular budget it receives from member states. Llewellyn-Smith says that countries outside of Europe including the United States, China and Japan might need to join CERN to form a new, global organization. “Almost certainly it will need a new structure,” he says.
The costly plan has detractors — even in the physics community. Sabine Hossenfelder, a theoretical physicist at the Frankfurt Institute for Advanced Studies in Germany, has emerged as a critic of pursuing ever higher energies when the scientific payback — apart from measuring the properties of known particles — is far from guaranteed. “I still think it’s not a good idea,” Hossenfelder says. “We’re talking about tens of billions. I just think there is not enough scientific potential in doing that kind of study right now.”
The new collider will be in uncharted territory, says Tara Shears, a physicist at the University of Liverpool, UK. While the LHC had a clear target to look for the Higgs boson as well as theorists’ well-motivated reasons to believe that there could be new particles in the range of masses it could explore, the situation now is different. “We don’t have an equivalent, rock-solid prediction now — and that makes knowing where and how to look for answers more challenging and higher risk.”
Still, she says, “We do know that the only way to find answers is by experiment and the only place to find them is where we haven’t been able to look yet.”
In closing the meeting, which most members attended remotely, CERN Council president Ursula Bassler said, “The big task now is in front of us, putting this strategy into reality.” She then popped a bottle of champagne before ending the teleconference.
NightWare developed a smartwatch device that’s supposed to deliver digital therapy to alleviate the effects of traumatic nightmares associated with post-traumatic stress disorder (PTSD).
The company’s app can collect biometric data, analyze sleep patterns, pinpoint the onset of a nightmare and provide vibro-tactile feedback to arouse the patient without completely waking them, according to the company.
Investors include: Minnesota State Board of Investment
"Many objects in the sky are UFOs, however, few UFOs are flying saucers. I study the latter and not the former", Stanton Friedman, Ph.D. Physicist
Circadia Health’s mission is to enable early detection of respiratory failure, a major cause of death. The company’s C100 System uses RADAR — no wires — to sense respiratory failure in patients up to 4 feet away. It’s meant to be an improvement over the manual method of measuring respiratory rate in which nursing staff visually count breaths per minute.
The FDA issued expedited clearance for Circadia’s contactless respiration rate (CResp) due to the demands created by COVID-19, the company announced Thursday.
“Our C100 uses RADAR to wirelessly look at your breathing pattern from up to 4 feet away,” Fares Siddiqui, co-founder and CEO of Circadia, told the DeviceTalks Weekly podcast. “From that we can pick up your respiratory rate and patterns and then apply machine learning in order to predict and prevent respiratory complications.”
For example, Siddiqui said, “breathlessness” is one of the early signs of distress in COVID-19 patients. “We can pick that up and enable timely interventions effectively.” –TS
Investors include: Village Global, SOSV, and Particular Ventures.
Quantum effects are pushing us around all the time, and we now have observational evidence of this somewhat disconcerting fact.
Researchers with the Laser Interferometer Gravitational-wave Observatory (LIGO) Scientific Collaboration have measured the tiny kick imparted to their exquisitely sensitive equipment by quantum fluctuations, a new study reports.
And that kick is indeed tiny, moving LIGO's 88-lb. (40 kilograms) mirrors just 10^-20 meters, the scientists found.
"A hydrogen atom is 10^-10 meters, so this displacement of the mirrors is to a hydrogen atom what a hydrogen atom is to us — and we measured that," study co-author Lee McCuller, a research scientist at the Massachusetts Institute of Technology's (MIT) Kavli Institute for Astrophysics and Space Research, said in a statement.
Other research groups have measured such quantum effects before, but never on this scale. The LIGO mirrors are about 1 billion times heavier than previously observed "kicked" objects, study team members said.
The LIGO project hunts for gravitational waves — the ripples in space-time caused by the acceleration of massive objects — using two detectors, one in Livingston, Louisiana and the other in Hanford, Washington.
Each detector is an L-shaped facility with legs 2.5 miles (4 kilometers) long. A laser at the crux of the "L" shines light down these legs, and 88-lb. mirrors at the end of each bounce the beams back. If the reflected beams arrive back at the crux at slightly different times, it's potential evidence of a gravitational wave distorting the fabric of space-time in the legs.
The LIGO team has used this strategy to great effect. The collaboration now has about a dozen confirmed gravitational-wave detections under its belt, including the first-ever such find, made in September 2015. Most of these events involve merging black holes, but two were caused by the collision of superdense, city-size stellar corpses known as neutron stars.
The LIGO detectors are incredibly sensitive and profoundly shielded from noise; they have to be, or else they'd be incapable of picking up gravitational waves. Making the groundbreaking 2015 detection, for example, required measuring a distance change 1,000 times smaller than the width of a proton, team members have said.
The new study harnesses that sensitivity and takes it to another level. The researchers, led by MIT physics graduate student Haocun Yu, used a "quantum squeezer," an add-on instrument they recently built allowing them to "tune" the quantum noise inside the detectors. That noise is created by minuscule particles popping into and out of existence, a constant crackling that pervades the universe.
"We think of the quantum noise as distributed along different axes, and we try to reduce the noise in some specific aspect," Yu said in the same statement.
The study team measured the total noise — both quantum and "classical," which is caused by ordinary vibrations — inside the detector. Then, with the aid of the squeezer, they subtracted out the classical noise during data analysis. This work revealed that quantum fluctuations in the laser light alone can move the detector mirrors, which hang from pendulums in a quadruple-suspension setup, by 10^-20 meters.
That number is in line with predictions made by theorists, team members said.
The new study, which was published Wednesday (July 1) in the journal Nature, has more than just gee-whiz appeal. The quantum squeezer allows the LIGO team to "manipulate the detector's quantum noise and reduce its kicks to the mirrors, in a way that could ultimately improve LIGO's sensitivity in detecting gravitational waves," Yu said.
Shock-dissipating fractal cubes could forge high-tech armor
3D printed fractal structures with closely spaced voids dissipate shockwaves five times better than solid cubes
Date: July 7, 2020
Source: DOE/Los Alamos National Laboratory
3D printed cubes,with intricate fractal voids efficiently dissipate shockwaves, potentially leading to new types of lightweight armor and materials to better withstand explosions and impacts.
Tiny, 3D printed cubes of plastic, with intricate fractal voids built into them, have proven to be effective at dissipating shockwaves, potentially leading to new types of lightweight armor and structural materials effective against explosions and impacts.
"The goal of the work is to manipulate the wave interactions resulting from a shockwave," said Dana Dattelbaum, a scientist at Los Alamos National Laboratory and lead author on a paper to appear in the journal AIP Advances. "The guiding principles for how to do so have not been well defined, certainly less so compared to mechanical deformation of additively manufactured materials. We're defining those principles, due to advanced, mesoscale manufacturing and design."
Shockwave dispersing materials that take advantage of voids have been developed in the past, but they typically involved random distributions discovered through trial and error. Others have used layers to reverberate shock and release waves. Precisely controlling the location of holes in a material allows the researchers to design, model and test structures that perform as designed, in a reproducible way.
The researchers tested their fractal structures by firing an impactor into them at approximately 670 miles per hour. The structured cubes dissipated the shocks five times better than solid cubes of the same material.
Although effective, it's not clear that the fractal structure is the best shock-dissipating design. The researchers are investigating other void- or interface-based patterns in search of ideal structures to dissipate shocks. New optimization algorithms will guide their work to structures outside of those that consist of regular, repeating structures. Potential applications might include structural supports and protective layers for vehicles, helmets, or other human-wearable protection.
Materials provided by DOE/Los Alamos National Laboratory. Note: Content may be edited for style and length.
1. D.M. Dattelbaum et al. Shockwave dissipation by interface-dominated porous structures. AIP Advances, 2020
Wearable BioSensor University of California San Diego
Wearable BioSensor Detects Vitamin C in Sweat
Sensors can track vitamin C levels and dietary adherence. By: Rehana Begg, May 21, 2020
A new medical device makes it easy to decide whether you need your daily dose of Vitamin C.
The non-invasive, wearable sensor, developed by a research team at University of California San Diego, provides a way to track a user’s daily nutritional intake and dietary adherence.
Wearable sensors are typically associated with tracking physical activity or for monitoring disease pathologies, such as diabetes. But the vitamin C sensor device is the first to track changes using an enzyme-based approach, noted Juliane Sempionatto, a Ph.D. candidate in nanoengineering at the UC San Diego Jacobs School of Engineering and first-author of the study “Epidermal Enzymatic Biosensors for Sweat Vitamin C: Toward Personalized Nutrition,” published in ACS Sensors.
“Wearable sensors have rarely been considered for precision nutrition,” said Joseph Wang, a professor of nanoengineering and director of the Center of Wearable Sensors at UC San Diego.
The sensor is paired with a circuit board that can transmit data wirelessly
University of California San Diego
The sensor consists of a flexible, polyurethane tattoo patch fitted with a sweat stimulation system, as well as an electrode sensor containing the enzyme ascorbate oxidase. When vitamin C is present, noted the study, the enzyme converts to dehydroascorbic acid. The resulting consumption of oxygen generates a current, which is measured by the device.
The device was tested in vitro as well as in four human subjects who consumed vitamin C supplements and fruit juices. According to the authors, the device detected changes in the levels of vitamin C over two hours.
In addition, the electrode detector was tested for cross-functionality. This was achieved by gauging its ability to detect temporal vitamin C changes in tears and saliva. The researchers report that differences observed in the vitamin C dynamics across different human subjects is an indication that the device holds promise for personal nutrition applications.
“Ultimately, this sort of device would be valuable for supporting behavioral changes around diet and nutrition,” said Sempionatto. “A user could track not just vitamin C, but other nutrients—a multivitamin patch, if you will. This is a field that will keep growing fast.”
The UC San Diego team is collaborating with global nutrition company DSM toward the use of wearable sensors for personal nutrition.
Dose of Vitamin C
The body needs vitamin C to form blood vessels, cartilage, muscle and collagen in bones. According to the Mayo Clinic, vitamin C is an antioxidant that might help protect cells against the effects of free radicals. (Free radicals are compounds formed when the body converts food into energy.)
“I hope that the new epidermal patch will facilitate the use of wearable sensors for non-invasive nutrition status assessments and tracking of nutrient uptake toward detecting and correcting nutritional deficiencies, assessing adherence to vitamin intake and supporting dietary behavior change,” said Joseph Wang, a professor of nanoengineering and director of the Center of Wearable Sensors at UC San Diego.
Vitamin C is also being studied in several clinical trials for its potential in supporting recovery from COVID-19, the disease caused by the novel SARS-CoV-2 virus. In a Canadian clinical trial run by physicians in Montreal and Toronto, researchers are investigating the use of intravenous vitamin C in COVID-19 patients. In a separate meta-analysis, the use and effect of vitamin C was evaluated in relation to the length of stay in the intensive care unit and duration of mechanical ventilation. Results are not definitive, but a recent study found that hospital stays could be shortened with the use of vitamin C.
With the race to find treatments for COVID-19, the researchers are also poised to get the vitamin C sensor technology into a clinical setting, in the event that vitamin C does prove to be a helpful treatment for the disease.
Last Edit: Jul 25, 2020 21:18:28 GMT by plutronus: Edit: Trying to Cause Problem Boards to save photos
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