Amazing Science

Wiring our brains up to computers could have a host of exciting applications – from controlling robotic prosthetics with our minds to restoring sight by feeding camera feeds directly into the vision center of our brains. Most brain-computer interface research to date has been conducted using electroencephalography (EEG) where electrodes are placed on the scalp to monitor the brain’s electrical activity. Achieving very high quality signals, however, requires a more invasive approach.

Integrating electronics with living tissue is complicated, though. Probes that are directly inserted into the gray matter have been around for decades, but while they are capable of highly accurate recording, the signals tend to degrade rapidly due to the buildup of scar tissue. Electrocorticography (ECoG), which uses electrodes placed beneath the skull but on top of the gray matter, has emerged as a popular compromise, as it achieves higher-accuracy recordings with a lower risk of scar formation.

But now researchers from the University of Texas have created new probes that are so thin and flexible, they don’t elicit scar tissue buildup. Unlike conventional probes, which are much larger and stiffer, they don’t cause significant damage to the brain tissue when implanted, and they are also able to comply with the natural movements of the brain.

In recent research published in the journal Science Advances, the team demonstrated that the probes were able to reliably record the electrical activity of individual neurons in mice for up to four months. This stability suggests these probes could be used for long-term monitoring of the brain for research or medical diagnostics as well as controlling prostheses, said Chong Xie, an assistant professor in the university’s department of biomedical engineering who led the research.

“Besides neuroprosthetics, they can possibly be used for neuromodulation as well, in which electrodes generate neural stimulation,” he told Singularity Hub in an email. “We are also using them to study the progression of neurovascular and neurodegenerative diseases such as stroke, Parkinson’s and Alzheimer’s.”

The group actually created two probe designs, one 50 microns long and the other 10 microns long. The smaller probe has a cross-section only a fraction of that of a neuron, which the researchers say is the smallest among all reported neural probes to the best of their knowledge.

Because the probes are so flexible, they can’t be pushed into the brain tissue by themselves, and so they needed to be guided in using a stiff rod called a “shuttle device.” Previous designs of these shuttle devices were much larger than the new probes and often led to serious damage to the brain tissue, so the group created a new carbon fiber design just seven microns in diameter.

At present, though, only 25 percent of the recordings can be tracked down to individual neurons – thanks to the fact that neurons each have characteristic waveforms – with the rest too unclear to distinguish from each other. “The only solution, in my opinion, is to have many electrodes placed in the brain in an array or lattice so that any neuron can be within a reasonable distance from an electrode,” said Chong. “As a result, all enclosed neurons can be recorded and well-sorted.”

Graphene-oxide membranes have attracted considerable attention as promising candidates for new filtration technologies. Now the much sought-after development of making membranes capable of sieving common salts has been achieved.

New research demonstrates the real-world potential of providing clean drinking water for millions of people who struggle to access adequate clean water sources. The new findings from a group of scientists at The University of Manchester were published today in the journal Nature Nanotechnology. Previously graphene-oxide membranes have shown exciting potential for gas separation and water filtration.

Graphene-oxide membranes developed at the National Graphene Institute have already demonstrated the potential of filtering out small nanoparticles, organic molecules, and even large salts. Until now, however, they couldn't be used for sieving common salts used in desalination technologies, which require even smaller sieves.

Previous research at The University of Manchester found that if immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the membrane along with water, but larger ions or molecules are blocked.

The Manchester-based group have now further developed these graphene membranes and found a strategy to avoid the swelling of the membrane when exposed to water. The pore size in the membrane can be precisely controlled which can sieve common salts out of salty water and make it safe to drink.

As the effects of climate change continue to reduce modern city's water supplies, wealthy modern countries are also investing in desalination technologies. Following the severe floods in California major wealthy cities are also looking increasingly to alternative water solutions.

When the common salts are dissolved in water, they always form a 'shell' of water molecules around the salts molecules. This allows the tiny capillaries of the graphene-oxide membranes to block the salt from flowing along with the water. Water molecules are able to pass through the membrane barrier and flow anomalously fast which is ideal for application of these membranes for desalination.

Professor Rahul Nair, at The University of Manchester said: "Realisation of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination technology. "This is the first clear-cut experiment in this regime. We also demonstrate that there are realistic possibilities to scale up the described approach and mass produce graphene-based membranes with required sieve sizes."

Fast Radio Bursts present one of modern astronomy's greatest mysteries: what or who in the Universe is transmitting short bursts of radio energy across the cosmos?

Manisha Caleb, a PhD candidate at Australian National University, Swinburne University of Technology and the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), has confirmed that the mystery bursts of radio waves that astronomers have hunted for ten years really do come from outer space.

Ms Caleb worked with Swinburne and University of Sydney colleagues to detect three of these Fast Radio Bursts (FRBs) with the Molonglo radio telescope 40 km from Canberra. Discovered almost 10 years ago at CSIRO's Parkes radio telescope, Fast Radio Bursts are millisecond-duration intense pulses of radio light that appear to be coming from vast distances. They are about a billion times more luminous than anything we have ever seen in our own Milky Way galaxy.

One potential explanation of the mystery is that they weren't really coming from outer space, but were some form of local interference tricking astronomers into searching for new theories of their 'impossible' radio energy. "Perhaps the most bizarre explanation for the FRBs is that they were alien transmissions," says ARC Laureate Fellow Professor Matthew Bailes from Swinburne.

"Conventional single dish radio telescopes have difficulty establishing that transmissions originate beyond the Earth's atmosphere," says Swinburne's Dr Chris Flynn.

In 2013 CAASTRO scientists and engineers realized that the Molonglo telescope's unique architecture could place a minimum distance to the FRBs due to its enormous focal length. A massive re-engineering effort began, which is now opening a new window on the Universe. The Molonglo telescope has a huge collecting area (18,000 square meters) and a large field of view (eight square degrees on the sky), which makes it excellent for hunting for fast radio bursts.

Ms Caleb's project was to develop software to sift through the 1000 TB of data produced each day. Her work paid off with the three new FRB discoveries. "It is very exciting to see the University of Sydney's Molonglo telescope making such important scientific discoveries by partnering with Swinburne's expertise in supercomputing", says Professor Anne Green of the University of Sydney.

Europe’s first cavefish has been discovered by a cave diver in Germany. The pale-coloured loach, shown above, is thought to have diverged from surface fish as glaciers from the last ice age receded some 16,000 to 20,000 years ago.

“Our first genetic studies, plus knowledge of the geological history of the region, suggest the cave loach population is amazingly young, certainly not older than 20,000 years,” says Jasminca Behrmann-Godel at the University of Konstanz in Germany, who led the team that analysed the fish. “Despite this short time span, the fish show trademark adaptions to cave life compared with loaches from surface locations nearby, including a pale body colouration, much smaller eyes, plus larger nostrils and barbels.”

It shows that adaptation to these subterranean habitats can be fast, and just a few thousand years might be enough for a fish to adapt to cave life, says Behrmann-Godel. “Cavefish could exist virtually everywhere in principle, and there’s no good reason to expect long evolution times for them to adapt to cave environments,” she says.

Simply dubbed “cave loach” or “barbatula” for now, the fish was discovered in 2015 by Joachim Kreiselmaier, an amateur cave diver. He was exploring a hard-to-reach water-filled cave labyrinth called the Danube-Aach System in southern Germany, which ultimately empties into the River Rhine. Kreiselmaier is a friend of Behrmann-Godel and sent her film and photographs of the strange fish he spotted.

Kreiselmaier says the section inhabited by the fish is notoriously difficult to reach, accessible only in dry spells when the underground river is sufficiently calm and clear to allow exploration. “To reach the area with the fish takes an hour, and involves periods of decompression that make the round trip as long as 3 hours,” he says.

Researchers from the European Graphene Flagship have developed a new microelectrode array neural probe based on graphene field-effect transistors (FETs) for recording brain activity at high resolution while maintaining excellent signal-to-noise ratio (quality). The new neural probe could lay the foundation for a future generation of in vivo neural recording implants, for patients with epilepsy, for example, and for disorders that affect brain function and motor control, the researchers suggest. It could possibly play a role in Elon Musk’s just-announced Neuralink “neural lace” research project.

Neural activity is measured by detecting the electric fields generated when neurons fire. These fields are highly localized, so ultra-small measuring devices that can be densely packed are required for accurate brain readings.

The new device has an microelectrode array of 16 graphene-based transistors arranged on a flexible substrate that can conform to the brain’s surface. Graphene provides biocompatibility, chemical stability, flexibility, and excellent electrical properties, which make it attractive for use in medical devices, especially for brain activity, the researchers suggest.

For a state-of-the-art example of microelectrode array use in the brain, see "Brain-computer interface advance allows paralyzed people to type almost as fast as some smartphone users."

In the early 1990s, Jacqueline Barton, the John G. Kirkwood and Arthur A. Noyes Professor of Chemistry at Caltech, discovered an unexpected property of DNA—that it can act like an electrical wire to transfer electrons quickly across long distances. Later, she and her colleagues showed that cells take advantage of this trait to help locate and repair potentially harmful mutations to DNA.

Now, Barton's lab has shown that this wire-like property of DNA is also involved in a different critical cellular function: replicating DNA. When cells divide and replicate themselves in our bodies—for example in the brain, heart, bone marrow, and fingernails—the double-stranded helix of DNA is copied. DNA also copies itself in reproductive cells that are passed on to progeny.

The new Caltech-led study, based on work by graduate student Elizabeth O'Brien in collaboration with Walter Chazin's group at Vanderbilt University, shows that a key protein required for replicating DNA depends on electrons traveling through DNA.

"Nature is the best chemist and knows exactly how to take advantage of DNA electron-transport chemistry," says Barton, who is also the Norman Davidson Leadership Chair of Caltech's Division of Chemistry and Chemical Engineering.

"The electron transfer process in DNA occurs very quickly," says O'Brien, lead author of the study, appearing in the February 24 2017 issue of Science. "It makes sense that the cell would utilize this quick-acting pathway to regulate DNA replication, which necessarily is a very rapid process."

For more than 50 years, the mathematician Neil Sloane has curated the authoritative collection of interesting and important integer sequences.

Neil Sloane is considered by some to be one of the most influential mathematicians of our time. That’s not because of any particular theorem the 75-year-old Welsh native has proved, though over the course of a more than 40-year research career at Bell Labs (later AT&T Labs) he won numerous awards for papers in the fields of combinatorics, coding theory, optics and statistics. Rather, it’s because of the creation for which he’s most famous: the Online Encyclopedia of Integer Sequences (OEIS), often simply called “Sloane” by its users.

This giant repository, which celebrated its 50th anniversary last year, contains more than a quarter of a million different sequences of numbers that arise in different mathematical contexts, such as the prime numbers (2, 3, 5, 7, 11 … ) or the Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13 … ). What’s the greatest number of cake slices that can be made with n cuts?

Look up sequence A000125 in the OEIS. How many chess positions can be created in n moves? That’s sequence A048987. The number of ways to arrange n circles in a plane, with only two crossing at any given point, is A250001. That sequence just joined the collection a few months ago. So far, only its first four terms are known; if you can figure out the fifth, Sloane will want to hear from you.

A mathematician whose research generates a sequence of numbers can turn to the OEIS to discover other contexts in which the sequence arises and any papers that discuss it. The repository has spawned countless mathematical discoveries and has been cited more than 4,000 times.

“Many mathematical articles explicitly mention how they were inspired by OEIS, but for each one that does, there are at least ten who do not mention it, not necessarily out of malice, but because they take it for granted,” wrote Doron Zeilberger, a mathematician at Rutgers University.

A recent scientific paper about the OEIS database can be found here (by J.M. Borwein).

Thomas Baruchel’s website shows images derived from complex analysis. John D. Cook used the ImageQuilts software by Edward Tufte and Adam Schwartz to create a large variety of scientific and artistic images.

Proteins that can be specifically modified during mitosis, the division process, to unleash an inherent death mechanism that self-eradicates duplicating cancer cells have been identified by researchers at Tel Aviv University. Many cancer patients struggle with the adverse effects of chemotherapy, still the most prescribed cancer treatment. For patients with pancreatic cancer and other aggressive cancers, the forecast is more grim: there is no known effective therapy.

Prof. Malka Cohen-Armon, study leader, said: “The discovery of an exclusive mechanism that kills cancer cells without impairing healthy cells, and the fact that this mechanism works on a variety of rapidly proliferating human cancer cells, is very exciting. According to the mechanism we discovered, the faster cancer cells proliferate, the faster and more efficiently they will be eradicated. The mechanism unleashed during mitosis may be suitable for treating aggressive cancers that are unaffected by traditional chemotherapy. Our experiments in cell cultures tested a variety of incurable human cancer types; breast, lung, ovary, colon, pancreas, blood, brain. This discovery impacts existing cancer research by identifying a new specific target mechanism that exclusively and rapidly eradicates cancer cells without damaging normally proliferating human cells.”

The newly-discovered mechanism involves the modification of specific proteins that affect the construction and stability of the spindle, the microtubular structure that prepares duplicated chromosomes for segregation into “daughter” cells during cell division. The researchers found that certain compounds called Phenanthridine derivatives were able to impair the activity of these proteins, which can distort the spindle structure and prevent the segregation of chromosomes. Once the proteins were modified, the cell was prevented from splitting, and this induced the cell’s rapid self-destruction.

“The mechanism we identified during the mitosis of cancer cells is specifically targeted by the Phenanthridine derivatives we tested,” Prof. Cohen-Armon said. “However, a variety of additional drugs that also modify these specific proteins may now be developed for cancer cell self-destruction during cell division. The faster the cancer cells proliferate, the more quickly they are expected to die.” The phenanthrenes PJ34, Phen and Tiq-A, the researchers found, modify kinesins (HSET/kifC1 and kif18A) and NuMA (nuclear mitotic apparatus protein) in a variety of human cancer cells. The most efficient cell killing activity was seen with phenanthridine PJ34, which caused significantly smaller aberrant spindles.

Reference: Visochek, L., Castiel, A., Mittelman, L., Elkin, M., Atias, D., Golan, T., Izraeli, S., Peretz, T., & Cohen-Armon, M. (2017) Exclusive destruction of mitotic spindles in human cancer cells Oncotarget, 8(13), 20813-20824

From Amazonia to Siberia, some human populations the world over communicate by whistling. More complex than it sounds, whistled speech intrigues linguists and neuroscientists alike. Linguist and bio-acoustician Julien Meyer tells us about this astonishing method of communication.

A team of astrophysicists has discovered that supermassive black holes at the centre of galaxies aren't just destroyers of stars, but also their creators.

Stellar black holes form from the collapse of a large star. They can have a mass of 20 times that of of our sun or higher, and they consume anything that gets too close, including a star. There's another category of these stellar gourmands: supermassive black holes. These have masses more than one billion times that of the sun and lurk at the centre of most galaxies, including our own. While it was suspected that these supermassive black holes could actually be giving rise to new stars while simultaneously destroying unfortunate interlopers, there wasn't enough direct evidence to support that theory. Until now.

Recently, a team of European astronomers was observing the collision of two galaxies some 600 million light-years away — each with a supermassive black hole at its centre —  using the Very Large Telescope (VLT) in Chile. There, they found evidence of new star birth from material being ejected from the black hole, called an outflow. While it might seem a contradiction that nothing can escape a black hole, but an outflow of gas is responsible for creating new stars, it's all about the location: nothing can escape a black hole once it gets so close that all matter is sucked in and can't escape.

However, the gases that swirl around the centre of the black hole — think of water going down a drain — exist in something called an accretion disc. It's from there that gases are heated to incredible temperatures and then are rapidly ejected into space. Astronomers believe that some of the material might be flung out of the galaxy altogether.

Airbus has been talking about its Vahana flying autonomous vehicle project for a while now, but at this year’s Geneva Motor Show, it’s showing off a concept design created in partnership with Italdesign. The demonstration vehicle offers modular functionality, meaning it an operate both on the ground and in the air, and Airbus thinks it’s one potential answer to the growing problem of urban traffic congestion.

As you can see, it’s suitably sci-fi in its design sensibilities, but it’s designed with practicality in mind. The concept vehicle is intended to work with others to form a network that can be summoned on demand, with passengers hailing a ride form an app on their mobile device. The capsule-based design can connect to either ground or air conveyance modules, letting customers specific their preferred method of transit. It’s also designed to be used in concert with other, existing transportation methods for maximum efficiency.

Airbus and Italdesign call their creation the ‘Pop.Up System,’ which includes the artificial intelligence platform that uses what it knows about any individual user, and available routes and transit options to determine the best travel options. The main vehicle itself is a passenger capsule, which holds the rider and which can be paired with either ground and air modules, as well as, Airbus suggests, with hyperloop systems down the line once that tech becomes more widely available.

Researchers have built the hottest thermal diode to date, which operates at temperatures of more than 600 K (326 °C). Thermal diodes may serve as the building blocks of future thermal computers.

The researchers, Assistant Professor Sidy Ndao and graduate student Mahmoud Elzouka at the University of Nebraska-Lincoln's Department of Mechanical & Materials Engineering, have published a paper on the NanoThermoMechanical diode in a recent issue of Nature's Scientific Reports. "We have demonstrated the building block of what could be the thermal computer of the future, and it works at very high temperatures," Ndao told Phys.org. "For someone who also actively works in electronics cooling, it makes you wonder 'What if we stopped cooling electronics all together?'

"Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. A few examples include the exploration of planet Venus with average temperature over 400 °C, and deep-Earth drilling for petroleum and geothermal energies. Also equally important is the opportunity that this technology presents for waste heat recovery with the development of thermal batteries."

The function of a thermal diode is to allow heat to flow primarily in one direction but not the other, similar to how an electronic diode allows electric current to flow primarily in one direction. This ability to control the direction of flow enables diodes to produce two distinct levels of a signal, forming the basis for the "0" and "1" binary logic levels.

The new thermal diode achieves two distinct levels of heat flow by controlling the distance between two surfaces: a moving terminal and a stationary terminal. The researchers showed that changing the relative temperatures of the two terminals changes the gap size between them, which changes the amount of heat transfer, which in turn depends on the direction of heat flow.

This is the first time that the relation among these four factors— temperature, separation gap, heat transfer rate, and heat flow direction—has been exploited for use in a thermal diode.

For the first time, engineers have succeeded in producing complex crystal lattices, so-called clathrates, from nanoparticles using DNA strands. The programmed synthesis of clathrates represents a template for the precision modeling of novel nanomaterials. These findings have recently been published in the acclaimed journal ‘Science’ (doi: 10.1126/science.aal3919).

DNA is the blueprint of biological life: it contains all hereditary information and the arrangement of its base pairs determines the structure of amino acids and ultimately the whole organism. For some years now, scientists have been using the structuring potential of DNA in other disciplines such as computer science or for creating new materials on the nano scale. In collaboration with the world’s leading nanotechnology experts from the University of Michigan and North Western University, FAU engineers have opened up a new era in DNA programmed material synthesis. The team has succeeded in reordering pyramid-shaped gold crystals to form complex clathrate compounds.

For the synthesis process, the 250 nanometre gold crystals – which in the experiment represent atoms that can form clathrates – are held in a suspension which is supplemented with artificial DNA. ‘The DNA strands attach to the gold particles and move them into a certain position during a self-assembling process,’ explains Professor Michael Engel, member of the Institute for Multiscale Simulation. ‘Depending on the length of the DNA sequences and the arrangement of the base pairs, different three-dimensional lattice structures form. Through DNA programming we can more or less determine the structure of the crystal lattice in a very precise manner.’

Clathrates are of particular interest in the field of materials research because they are composed of nuclear cages in which other substances, usually gases, can be embedded. ‘The controlled production of colloidal clathrates opens up a wide range of possible applications,’ says Michael Engel. ‘Materials could be used for recognizing proteins or viruses and targeted manipulation of certain parameters of the crystal lattice can lead to material properties which are not achievable in simpler colloidal crystals.’

What will happen as we enter the era of human augmentation, artificial intelligence and government-by-algorithm? James Barrat, author of Our Final Invention, said: “Coexisting safely and ethically with intelligent machines is the central challenge of the twenty-first century.”

A lot of folks are earnestly exploring the topic. “Will scientists soon be able to create supercomputers that can read a newspaper with understanding, or write a news story, or create novels, or even formulate laws?” asks J. Storrs Hall in Beyond AI: Creating the Conscience of the Machine (2007). “And if machine intelligence advances beyond human intelligence, will we need to start talking about a computer’s intentions?”

Sharing this concern, SpaceX/Tesla entrepreneur Elon Musk has joined with Y Combinator founder Sam Altman to establish OpenAI, an endeavor that aims to keep artificial intelligence research — and its products — accountable by maximizing transparency and openness.

Among the most-worried is Swiss author Gerd Leonhard, whose new book Technology Vs. Humanity: The Coming Clash Between Man and Machine, coins an interesting term, “androrithm,” to contrast with the algorithms that are implemented in every digital calculating engine or computer. Some foresee algorithms ruling the world with the inexorable automaticity of reflex, and Leonhard asks: “Will we live in a world where data and algorithms triumph over androrithms… i.e., all that stuff that makes us human?”

Artificial intelligence. Cognitive computing. The Singularity. Digital obesity. Printed food. The Internet of Things. The death of privacy. The end of work-as-we-know-it, and radical longevity: The imminent clash between technology and humanity is already rushing towards us. What moral values are you prepared to stand up for—before being human alters its meaning forever? Before it’s too late, we must stop and ask the big questions: How do we embrace technology without becoming it? When it happens — gradually, then suddenly — the machine era will create the greatest watershed in human life on Earth. 

The success of a rat-to-mouse pancreas transplant suggests that such interspecies transplants could help meet the need for donor organs.

Mouse pancreases grown in rats generate functional, insulin-producing cells that can reverse diabetes when transplanted into mice with the disease, according to researchers at the Stanford University School of Medicine and the Institute of Medical Science at the University of Tokyo. These findings, published in Nature, suggest that a similar technique could one day be used to generate matched, transplantable human organs in large animals like pigs or sheep.

About 76,000 people in the United States are currently waiting for an organ transplant, but organs are in short supply. Generating genetically matched human organs in large animals could relieve the shortage and release transplant recipients from the need for lifelong immunosuppression, the researchers say. To conduct the work, the researchers implanted mouse pluripotent stem cells into early rat embryos. The rats had been genetically engineered to be unable to develop their own pancreas and were thus forced to rely on the mouse cells for the development of the organ. Once the rats were born and grown, the researchers transplanted the insulin-producing cells, which cluster together in groups called islets, from the rat-grown pancreases into mice genetically matched to the stem cells that formed the pancreas. These mice had been given a drug to cause them to develop diabetes.

“We found that the diabetic mice were able to normalize their blood glucose levels for over a year after the transplantation of as few as 100 of these islets,” said Hiromitsu Nakauchi, a professor of genetics at Stanford. “Furthermore, the recipient animals only needed treatment with immunosuppressive drugs for five days after transplantation, rather than the ongoing immunosuppression that would be needed for unmatched organs.”

The researchers’ current findings come on the heels of a previous study in which they grew rat pancreases in mice. Although the organs appeared functional, they were the size of a normal mouse pancreas rather than a larger rat pancreas. As a result, there were not enough functional islets in the smaller organs to successfully reverse diabetes in rats.

Researchers at the University of East Anglia (UEA) have shown that when photons – the fundamental particles of light – are created in pairs, they can emerge from different, rather than the same, location. The ground-breaking research could have significant implications for quantum physics, the theoretical basis of modern physics. Until now, the general assumption was that such photon pairs necessarily originate from single points in space.

Quantum entanglement – when particles are linked so closely that what affects one directly affects the other - is widely used in labs in numerous processes from quantum cryptography to quantum teleportation. The UEA team were studying a process called spontaneous parametric down-conversion (SPDC), in which photon beams are passed through a crystal to generate entangled pairs of photons.

Prof David Andrews in UEA’s School of Chemistry said: “When the emergent pairs equally share the energy of the input, this is known as degenerate down-conversion, or DDC. “Until now, it has been assumed that such paired photons come from the same location. Now, the identification of a new delocalized mechanism shows that each photon pair can be emitted from spatially separated points, introducing a new positional uncertainty of a fundamental quantum origin.”

The entanglement of the quantum states in each pair has important applications in quantum computing - theoretical computation systems that could potentially process big data problems at incredible speeds - as well as other areas of quantum physics.

The findings are also significant because they place limits on spatial resolution. Prof Andrews said: “Everything has a certain quantum ‘fuzziness’ to it, and photons are not the hard little bullets of light that are popularly imagined.”

The study ‘Non-localized generation of correlated photon pairs in degenerate down-conversion’ by Kayn A. Forbes, Jack S. Ford, and David L. Andrews is published in the journal Physical Review Letters.

Chromatin is reprogrammed after fertilization to produce a totipotent zygote with the potential to generate a new organism1. The maternal genome inherited from the oocyte and the paternal genome provided by sperm coexist as separate haploid nuclei in the zygote. How these two epigenetically distinct genomes are spatially organized is poorly understood. Existing chromosome conformation capture-based methods2, 3, 4, 5 are not applicable to oocytes and zygotes owing to a paucity of material.

To study three-dimensional chromatin organization in rare cell types, a team of scientists developed a single-nucleus Hi-C (high-resolution chromosome conformation capture) protocol that provides greater than tenfold more contacts per cell than the previous method2. They were able to show that chromatin architecture is uniquely reorganized during the oocyte-to-zygote transition in mice and is distinct in paternal and maternal nuclei within single-cell zygotes. Features of genomic organization including compartments, topologically associating domains (TADs) and loops are present in individual oocytes when averaged over the genome, but the presence of each feature at a locus varies between cells. At the sub-megabase level, they observed stochastic clusters of contacts that can occur across TAD boundaries but average into TADs. Notably, they found that TADs and loops, but not compartments, are present in zygotic maternal chromatin, suggesting that these are generated by different mechanisms.

Taken together, these results demonstrate that the global chromatin organization of zygote nuclei is fundamentally different from that of other interphase cells. An understanding of this zygotic chromatin ‘ground state’ could potentially provide insights into reprogramming cells to a state of totipotency.

The Big Bang Theory predicts three times as much lithium as observed. Where are the scientists hiding our lithium?

The missing lithium problem is centered around the earliest stages of the Universe: from about 10 seconds to 20 minutes after the Big Bang. The Universe was super hot and it was expanding rapidly. This was the beginning of what’s called the Photon Epoch. At that time, atomic nuclei formed through nucleosynthesis. But the extreme heat that dominated the Universe prevented the nuclei from combining with electrons to form atoms. The Universe was a plasma of nuclei, electrons, and photons.

Only the lightest nuclei were formed during this time, including most of the helium in the Universe, and small amounts of other light nuclides, like deuterium and our friend lithium. For the most part, heavier elements weren’t formed until stars appeared, and took on the role of nucleosynthesis.

The problem is that our understanding of the Big Bang tells us that there should be three times as much lithium as there is. The BBT gets it right when it comes to other primordial nuclei. Our observations of primordial helium and deuterium match the BBT’s predictions. So far, scientists haven’t been able to resolve this inconsistency. But a new paper from researchers in China may have solved the puzzle.

One assumption in Big Bang nucleosynthesis is that all of the nuclei are in thermodynamic equilibrium, and that their velocities conform to what’s called the classical Maxwell-Boltzmann distribution. But the Maxwell-Boltzmann describes what happens in what is called an ideal gas. Real gases can behave differently, and this is what the researchers propose: that nuclei in the plasma of the early photon period of the Universe behaved slightly differently than thought.

Researchers say the lineages of HSV-1 and HSV-2 show herpes viruses mixed genomes and moved from chimps to humans. How it was transmitted is a bit of a mystery.

It’s ovulation in the lab. A simulated female reproductive system behaves almost like the real thing over 28 days. “Menstruation in a dish is one of my goals,” says Julie Kim of Northwestern University in Chicago. Kim works with organoids – small 3D clumps of tissue that behave more naturally than traditional, flat cell cultures. Linking different organoids together enables researchers to study complex organ systems in miniature, an approach that could lead to new insights and less animal testing.

Now Kim’s team has hooked up tissue from the ovaries, uterus, cervix and fallopian tubes, as well as the liver, which makes compounds that help to transport hormones. The tissues responded to hormones made by the mini ovary: oestrogen in the first two weeks, then progesterone for the next two weeks. In the first half of the cycle, eggs grew and burst out of the ovary – mimicking ovulation. Tiny hairs in the fallopian tube began to beat faster, as if to waft the egg along, while cells in the uterus proliferated.

But the uterine cells didn’t die and break away during the progesterone phase, which normally triggers menstruation – probably because the uterine organoid had no blood vessels. Kim is now introducing these, but she hasn’t yet managed to get them to break down, which should prompt the uterine cells to die off. If Kim’s team manages to complete the miniature menstrual cycle, it may lead to treatments for painful periods, fibroids and infertility.

“Having this functional axis between the ovaries and the other organs is what makes this so interesting,” saysAnthony Atala at the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina. “In our body it’s not just the isolated organ that’s doing the work; you have these interactions with other organs.”

Journal reference: Nature Communications, DOI: 10.1038/ncomms14584