Scientists have grown a miniature brain in a dish with a spinal cord and muscles attached, an advance that promises to accelerate the study of conditions such as motor neurone disease.

The lentil-sized grey blob of human brain cells were seen to spontaneously send out tendril-like connections to link up with the spinal cord and muscle tissue, which was taken from a mouse. The muscles were then seen to visibly contract under the control of the so-called brain organoid.

The research is is the latest in a series of increasingly sophisticated approximations of the human brain grown in the laboratory – this time with something approaching a central nervous system attached.

Madeline Lancaster, who led the work at the Medical Research Council’s Laboratory of Molecular Biology in Cambridge, said: “We like to think of them as mini-brains on the move.”

The scientists used a new method to grow the miniature brain from human stem cells, which allowed the organoid to reach a more sophisticated stage of development than previous experiments. The latest blob shows similarities, in terms of the variety of neurons and their organisation, to the human foetal brain at 12-16 weeks of pregnancy.

However, the scientists said the structure was still too small and primitive to have anything approaching thoughts, feelings or consciousness.

“It’s still a good idea to have that discussion every time we take it a step further,” said Lancaster. “But we agree generally that we’re still very far away from that.”

While a fully developed human brain has 80-90bn neurons, the organoid has a couple of million, placing it somewhere between a cockroach and a zebrafish in terms of volume of grey matter.

Previously, the sophistication of the organoids scientists had been able to achieve had been limited by the lack of a nutrient supply to the centre of the blob. Once it reached a certain size, the neurons in the centre would become cut off from their nutrient supply and start to die off, and the structure would stop developing.

In the latest research, the scientists grew the organoid and then used a tiny vibrating blade to cut it into half millimetre-thick slices which were placed on a membrane, floating on a nutrient-rich liquid. This meant the entire slice had access to energy and oxygen and it continued developing and forming new connections when it was kept in culture for a year.

Alongside the organoid, the scientists added in a 1mm-long spinal cord, taken from a mouse embryo, and the surrounding back muscle. The brain cells automatically began to send out neuronal connections, linked up with the spinal cord and began sending electrical impulses, which caused the muscles to twitch.

The ambition is to use systems like this to study how the human brain and nervous system develop and why things go wrong in illnesses such as motor neurone disease, epilepsy and schizophrenia.

“Obviously we’re not just trying to create something for the fun of it,” said Lancaster. “We want to use this to model diseases and to understand how these networks are set up in the first place.”

Gray Camp, a geneticist at the Institute of Molecular and Clinical Ophthalmology in Basel, Switzerland, who was not involved in the latest work, described the advance as “a big step for the field”. “It’s extremely exciting to see evidence of functional nerve tracts growing out of developing human brain tissue and innervating other tissues,” he said.

The findings are published in the journal Nature Neuroscience.

Source: Scientists grow ‘mini-brain on the move’ that can contract muscle

The move is intended to send a clear signal to maverick researchers, and the scientific community more broadly, that any attempt to rewrite the DNA of sperm, eggs or embryos destined for live births is not acceptable.

Beyond a formal freeze on any such work, the experts want countries to register and declare any plans that scientists may put forward in the future, and have these discussed through an international body, potentially run by the World Health Organisation.

Alongside technical debates about the possible benefits of creating genetically modified babies, the scientists said no decisions should be made to go ahead without broad public support.

“What we want to see are wise and open decisions,” said Eric Lander, founding director of the Broad Institute of MIT and Harvard in Cambridge, Massachusetts. “We want to make sure that countries don’t do things secretly, that we declare what we’re thinking, discuss it openly, and be prepared for debate and disagreement.”

Lander, who co-chaired Barack Obama’s council of advisors on science and technology, calls for the moratorium with 16 other experts in the journal Nature. Emmanuelle Charpentier and Feng Zhang, who helped discover and develop the most common gene editing tool, Crispr, contributed to the article.

Source: Scientists call for global moratorium on gene editing of embryos | Science | The Guardian

Designer babies are a great idea, if I could I would definitely create my own! This sounds a bit like an anti-diversity policy to me. Go! Create!

Researchers from the Moscow Institute of Physics and Technology teamed up with colleagues from the U.S. and Switzerland and returned the state of a quantum computer a fraction of a second into the past. They also calculated the probability that an electron in empty interstellar space will spontaneously travel back into its recent past. The study is published in Scientific Reports.

“This is one in a series of papers on the possibility of violating the second law of thermodynamics. That law is closely related to the notion of the arrow of time that posits the one-way direction of time from the past to the future,” said the study’s lead author Gordey Lesovik, who heads the Laboratory of the Physics of Quantum Information Technology at MIPT.

“We began by describing a so-called local perpetual motion machine of the second kind. Then, in December, we published a paper that discusses the violation of the second law via a device called a Maxwell’s demon,” Lesovik said. “The most recent paper approaches the same problem from a third angle: We have artificially created a state that evolves in a direction opposite to that of the thermodynamic arrow of time.”

What makes the future different from the past

Most laws of physics make no distinction between the future and the past. For example, let an equation describe the collision and rebound of two identical billiard balls. If a close-up of that event is recorded with a camera and played in reverse, it can still be represented by the same equation. Moreover, it is not possible to distinguish from the recording if it has been doctored. Both versions look plausible. It would appear that the billiard balls defy the intuitive sense of time.

However, imagine recording a cue ball breaking the pyramid, the billiard balls scattering in all directions. In that case, it is easy to distinguish the real-life scenario from reverse playback. What makes the latter look so absurd is our intuitive understanding of the second law of thermodynamics—an isolated system either remains static or evolves toward a state of chaos rather than order.

Most other laws of physics do not prevent rolling billiard balls from assembling into a pyramid, infused tea from flowing back into the tea bag, or a volcano from “erupting” in reverse. But these phenomena are not observed, because they would require an isolated system to assume a more ordered state without any outside intervention, which runs contrary to the second law. The nature of that law has not been explained in full detail, but researchers have made great headway in understanding the basic principles behind it.

Spontaneous time reversal

Quantum physicists from MIPT decided to check if time could spontaneously reverse itself at least for an individual particle and for a tiny fraction of a second. That is, instead of colliding billiard balls, they examined a solitary electron in empty interstellar space.

“Suppose the electron is localized when we begin observing it. This means that we’re pretty sure about its position in space. The laws of quantum mechanics prevent us from knowing it with absolute precision, but we can outline a small region where the electron is localized,” says study co-author Andrey Lebedev from MIPT and ETH Zurich.

The physicist explains that the evolution of the electron state is governed by Schrödinger’s equation. Although it makes no distinction between the future and the past, the region of space containing the electron will spread out very quickly. That is, the system tends to become more chaotic. The uncertainty of the electron’s position is growing. This is analogous to the increasing disorder in a large-scale system—such as a billiard table—due to the second law of thermodynamics.

“However, Schrödinger’s equation is reversible,” adds Valerii Vinokur, a co-author of the paper, from the Argonne National Laboratory, U.S. “Mathematically, it means that under a certain transformation called complex conjugation, the equation will describe a ‘smeared’ electron localizing back into a small region of space over the same time period.” Although this phenomenon is not observed in nature, it could theoretically happen due to a random fluctuation in the cosmic microwave background permeating the universe.The team set out to calculate the probability to observe an electron “smeared out” over a fraction of a second spontaneously localizing into its recent past. It turned out that even across the entire lifetime of the universe—13.7 billion years—observing 10 billion freshly localized electrons every second, the reverse evolution of the particle’s state would only happen once. And even then, the electron would travel no more than a mere one ten-billionth of a second into the past.

Large-scale phenomena involving billiard balls and volcanoes obviously unfold on much greater timescales and feature an astounding number of electrons and other particles. This explains why we do not observe old people growing younger or an ink blot separating from the paper.

Reversing time on demand

The researchers then attempted to reverse time in a four-stage experiment. Instead of an electron, they observed the state of a quantum computer made of two and later three basic elements called superconducting qubits.

• Stage 1: Order. Each qubit is initialized in the ground state, denoted as zero. This highly ordered configuration corresponds to an electron localized in a small region, or a rack of billiard balls before the break.
• Stage 2: Degradation. The order is lost. Just like the electron is smeared out over an increasingly large region of space, or the rack is broken on the pool table, the state of the qubits becomes an ever more complex changing pattern of zeros and ones. This is achieved by briefly launching the evolution program on the quantum computer. Actually, a similar degradation would occur by itself due to interactions with the environment. However, the controlled program of autonomous evolution will enable the last stage of the experiment.
• Stage 3: Time reversal. A special program modifies the state of the quantum computer in such a way that it would then evolve “backwards,” from chaos toward order. This operation is akin to the random microwave background fluctuation in the case of the electron, but this time, it is deliberately induced. An obviously far-fetched analogy for the billiards example would be someone giving the table a perfectly calculated kick.
• Stage 4: Regeneration. The evolution program from the second stage is launched again. Provided that the “kick” has been delivered successfully, the program does not result in more chaos but rather rewinds the state of the qubits back into the past, the way a smeared electron would be localized or the billiard balls would retrace their trajectories in reverse playback, eventually forming a triangle.

The researchers found that in 85 percent of the cases, the two-qubit quantum computer returned back into the initial state. When three qubits were involved, more errors happened, resulting in a roughly 50 percent success rate. According to the authors, these errors are due to imperfections in the actual quantum computer. As more sophisticated devices are designed, the error rate is expected to drop.

Interestingly, the time reversal algorithm itself could prove useful for making quantum computers more precise. “Our algorithm could be updated and used to test programs written for quantum computers and eliminate noise and errors,” Lebedev explained.

Read more at: https://phys.org/news/2019-03-physicists-reverse-quantum.html#jCp

Source: Physicists reverse time using quantum computer

A team of Boston University researchers recently stuck a loudspeaker into one end of a PVC pipe. They cranked it up loud. What did they hear? Nothing.

How was this possible? Did they block the other end of the pipe with noise canceling foams or a chunk of concrete? No, nothing of the sort. The pipe was actually left open save for a small, 3D-printed ring placed around the rim. That ring cut 94% of the sound blasting from the speaker, enough to make it inaudible to the human ear.

Dubbed an “acoustic meta-material,” the ring was printed from a mathematically modeled design, shaped in such a way that it can catch certain frequencies passing through the air and reflect them back toward their source. Typical acoustic paneling works differently, absorbing sound and turning the vibrations into heat. But what’s particularly trippy is that this muffler is completely open. Air and light can travel through it–just sound cannot.

The implications for architecture and interior design are remarkable, because these metamaterials could be applied to the built environment in many different ways. For instance, they could be stacked to build soundproof yet transparent walls. Cubicles will never be the same.

The researchers also believe that HVAC systems could be fitted with these silencers, and drones could have their turbines muted with such rings. Even in MRI machines, which can be harrowingly loud for patients trapped in a small space, could be quieted. There’s really no limit to the possibilities, but it does sound like these silencers will need to be tailored to circumstance. “The idea is that we can now mathematically design an object that can blocks the sounds of anything,” says Boston University professor Xin Zhang, in a press release.

Source: Mathematically perfect rings could soundproof the world