Amazing Science

A Multiverse – where our Universe is only one of many – might not be as inhospitable to life as previously thought, according to new research. Questions about whether other universes might exist as part of a larger Multiverse, and if they could harbor life, are burning issues in modern cosmology.

Now new research led by Durham University, UK, and Australia’s University of Sydney, Western Sydney University and the University of Western Australia, has shown that life could potentially be common throughout the Multiverse, if it exists. The key to this, the researchers say, is dark energy, a mysterious “force” that is accelerating the expansion of the Universe.

Multiverse theory

Scientists say that current theories of the origin of the Universe predict much more dark energy in our Universe than is observed. Adding larger amounts would cause such a rapid expansion that it would dilute matter before any stars, planets or life could form.

The Multiverse theory, introduced in the 1980s, can explain the “luckily small” amount of dark energy in our Universe that enabled it to host life, among many universes that could not.

Using huge computer simulations of the cosmos, the new research has found that adding dark energy, up to a few hundred times the amount observed in our Universe, would actually have a modest impact upon star and planet formation. This opens up the prospect that life could be possible throughout a wider range of other universes, if they exist, the researchers said.

The findings are published in two related papers in the journal Monthly Notices of the Royal Astronomical Society. The Durham University led paper can be read here and the University of Sydney led paper is here.

The simulations were produced under the EAGLE (Evolution and Assembly of GaLaxies and their Environments)project - one of the most realistic simulations of the observed Universe.

Star formation

Jaime Salcido, a postgraduate student in Durham University’s Institute for Computational Cosmology, said: “For many physicists, the unexplained but seemingly special amount of dark energy in our Universe is a frustrating puzzle. “Our simulations show that even if there was much more dark energy or even very little in the Universe then it would only have a minimal effect on star and planet formation, raising the prospect that life could exist throughout the Multiverse.”

Dr Luke Barnes, a John Templeton Research Fellow at Western Sydney University, said: “The Multiverse was previously thought to explain the observed value of dark energy as a lottery - we have a lucky ticket and live in the Universe that forms beautiful galaxies which permit life as we know it. Our work shows that our ticket seems a little too lucky, so to speak. It’s more special than it needs to be for life. This is a problem for the Multiverse; a puzzle remains.”

MIT researchers have engineered bacteria with “multicolor vision” — E. coli that recognize red, green, or blue (RGB) light and, in response to each color, express different genes that perform different biological functions.

To showcase the technology, the researchers produced several colored images on culture plates — one of which spells out “MIT” — by using RGB lights to control the pigment produced by the bacteria. Outside of the lab, the technology could also prove useful for commercial, pharmaceutical, and other applications.

The E. coli is programmed with a protein- and enzyme-based system, analogous to a computer chip, with several different modules to process the light input and produce a biological output. In computing terms, a “sensor array” first becomes activated in the presence of either red, green, or blue light, and a “circuit” processes the signal. Then, a “resource allocator” connects the processed information to “actuators” that implement the corresponding biological function.

Think of the new E. coli as microbial marionettes, with colored light instead of puppet strings making the bacteria act in a certain way, says MIT professor of biological engineering Chris Voigt, co-author of a paper in Nature describing the technology. “Using different colors, we can control different genes that are being expressed,” he says.

People with high blood pressure could get real-time data about sodium intake.

If you’re one of the approximately 36 million adults in the United States with high blood pressure (also called hypertension), your doctor may have lectured you about the importance of reducing your sodium intake. Maybe you listened, and maybe you even intended to follow your doctor’s advice. But sodium, the primary component of table salt, is everywhere in our modern diets—in snack foods, in restaurant meals, even in beverages—and your good intentions probably didn’t get you very far. 

To tackle this problem, researchers at the Georgia Institute of Technologyhave invented a flexible electronic sensor that can be embedded in a dental retainer for real-time monitoring of sodium intake. The device, which theydescribed in the journal PNAS, could send info to your phone, giving you instant data about whether you’re busting your low-sodium diet.

Whether you decide to change your diet based on that data is another question entirely. But getting the data is the first step. 

W. Hong Yeo, an assistant professor of micro and nano engineering who led the research team, says it would also be possible to stick the sensor directly to the tongue or the roof of the mouth, or to laminate it onto a tooth. The soft retainer they used in this experiment was just phase one. “For the first prototype device, we wanted to offer easy handling and cleaning capability via the integration with a soft retainer,” he said.

Yeo says the biggest challenge was making the entire electronic device soft, flexible, and comfortable enough to wear in the mouth. So the team designed a chip that uses stretchable circuits mounted on an ultrathin porous membrane.

UCLA biologists report they have transferred a memory from one marine snail to another, creating an artificial memory, by injecting RNA from one to another. This research could lead to new ways to lessen the trauma of painful memories with RNA and to restore lost memories.

"I think in the not-too-distant future, we could potentially use RNA to ameliorate the effects of Alzheimer's disease or post-traumatic stress disorder," said David Glanzman, senior author of the study and a UCLA professor of integrative biology and physiology and of neurobiology. The team's research is published May 14 ineNeuro, the online journal of the Society for Neuroscience.

RNA has been widely known as a cellular messenger that makes proteins and carries out DNA's instructions to other parts of the cell. It is now understood to have other important functions besides protein coding, including regulation of a variety of cellular processes involved in development and disease.

The researchers gave mild electric shocks to the tails of a species of marine snail called Aplysia. The snails received five tail shocks, one every 20 minutes, and then five more 24 hours later. The shocks enhance the snail's defensive withdrawal reflex, a response it displays for protection from potential harm. When the researchers subsequently tapped the snails, they found those that had been given the shocks displayed a defensive contraction that lasted an average of 50 seconds, a simple type of learning known as "sensitization." Those that had not been given the shocks contracted for only about one second.

The life scientists extracted RNA from the nervous systems of marine snails that received the tail shocks the day after the second series of shocks, and also from marine snails that did not receive any shocks. Then the RNA from the first (sensitized) group was injected into seven marine snails that had not received any shocks, and the RNA from the second group was injected into a control group of seven other snails that also had not received any shocks.

Remarkably, the scientists found that the seven that received the RNA from snails that were given the shocks behaved as if they themselves had received the tail shocks: They displayed a defensive contraction that lasted an average of about 40 seconds. "It's as though we transferred the memory," said Glanzman, who is also a member of UCLA's Brain Research Institute.

Single optical photon detectors typically absorb an incoming photon and use that energy to generate an electrical signal, or “click,” that indicates the arrival of a single quantum of light. Such a high-precision measurement—at the quantum limit of detection—is a remarkable achievement, but the price of that click is in some cases too high, as the measurement completely destroys the photon. If the photon could be saved, then it could be measured by other detectors or entangled with other photons.

Fortunately, there is a way to detect single photons without destroying them. This quantum nondemolition photon detection was recently demonstrated in the optical domain [1], and now the feat has been repeated for microwaves. Two research groups—one based at the Swiss Federal Institute of Technology (ETH) in Zurich and the other at the University of Tokyo in Japan—have utilized a cavity-qubit combination to detect a single microwave photon through its reflection off the cavity [2, 3]. The ability to measure microwaves like this without destroying them could help in generating entanglement between distant qubits as well as provide a route toward all-photon-based quantum computation.

The reliable detection of a single microwave photon has been an outstanding goal in microwave quantum optics for the past decade. The challenge is greater than in the optical regime, since a single microwave photon carries 5 orders of magnitude less energy than an optical photon. While researchers have developed techniques to measure single photons stored in a highly confining cavity [4, 5], there is particular interest in the detection of propagating microwave photons. A few single microwave photon detectors have been demonstrated in the last few years [6–8], yet these detectors all resulted in the destruction of the detected photon.

Experiments on Lawrence Livermore National Laboratory's National Ignition Facility (NIF) are providing scientists with new insights into the turbulent after-effects of a supernova explosion.

Experiments on Lawrence Livermore National Laboratory's National Ignition Facility (NIF) are providing scientists with new insights into the turbulent after-effects of a supernova explosion. The studies also could inform efforts to achieve self-sustaining nuclear fusion on NIF and other high-energy laser systems.

When stars of a certain mass collapse and then violently explode, material called ejecta expands rapidly and is then decelerated by the surrounding circumstellar medium. This results in Rayleigh-Taylor (RT) hydrodynamic instabilities -- the mixing of denser with less-dense material.

The same instabilities can affect the performance of inertial confinement fusion (ICF) and high-energy density (HED) science experiments such as those conducted on NIF, the world’s highest-energy laser system. The instabilities can cause too much target capsule material to mix with the fuel, quenching the fusion reaction.

The supernova studies, conducted by an international team of researchers led by the University of Michigan (UM) and LLNL physicists Hye-Sook Park and Channing Huntington, found that high energy fluxes and the resulting heat could reduce RT growth in supernova remnants (SNRs) -- something previous astrophysics models had not considered. The results were reported in a Nature Communications paper published online on April 19.

“Rayleigh-Taylor instabilities have been studied for more than 100 years,” said Carolyn Kuranz, director of UM’s Center for Laser Experimental Astrophysical Research and an associate research scientist of climate and space sciences and engineering. “These instabilities are important in supernova dynamics, but the effects of these high-energy fluxes, these mechanisms that cause heating, have never been studied in this context.” The researchers said realistic models of SNRs “must account for the effects of thermal conduction to accurately predict their evolution at epochs immediately following the shock breakout.”

“These heating mechanisms reduce mixing and can have a dramatic effect on the evolution of a supernova,” Kuranz said. “In our experiment, we found that mixing was reduced by 30 percent and that reduction could continue to increase over time.”

That finding is potentially important for NIF because “the Rayleigh-Taylor instability is a very basic ingredient in understanding NIF’s performance,” Park said. “The effect of large energy flux and the basic science of the RT theory and application are quite relevant to ICF and HED science.”

Independent research teams identified and sequenced hepatitis B strains going back thousands of years from samples in Europe, uncovering now-extinct lineages.

Mutations, recombination events, and apparent lineage extinctions may have obscured some of the genetic clues needed to clearly untangle the origins of the hepatitis B virus (HBV), two new studies suggest. 

"The estimates people have been dealing with before, in terms of [HBV] mutation rate, for example, have been problematic because they've only been using contemporary strains, which are just a subset of what has been around," Eske Willerslev, a researcher affiliated with the University of Copenhagen's Centre for GeoGenetics, the University of Cambridge, and the Wellcome Trust Sanger Institute, said in a conference call this week.

Willerslev and colleagues from Denmark, the UK, and elsewhere published apaper on ancient HBV in Nature this week. For that study, they tapped into HBV sequences generated as byproducts of ancient human genome sequencing studies on Bronze and Iron Age individuals, generating full or partial genome sequences for a dozen 800- to 4,500-year-old HBV samples from Eurasia.

"After we sequenced the [ancient human] genomes by shotgun sequencing, the vast majority of the DNA we were getting out was actually non-human," Willerslev explained. "Originally, this was nothing we paid much attention to. It was just expensive and kind of a waste product. But now, we have started investigating this waste product for possible pathogens."

By sifting through sequence data for 167 Bronze Age individuals and 137 individuals from a study centered on the Iron Age, the researchers narrowed in on 25 samples containing sequences that lined up with the HBV genome. From there, they used HBV-targeted enrichment and Illumina HiSeq2500 shotgun sequencing to generate 0.4-fold to more than 89-fold average coverage of each ancient HBV genome, subsequently focusing on the 12 most completely sequenced samples.

The team's phylogenetic analysis, which included more than 100 modern-day HBV isolates from humans and non-human primates, suggests that the HBV tree stretches between 8,600 and 20,900 years. It also uncovered previously unknown HBV genotypes and sequence recombinations, along with ancient European genotypes that are now better known for causing infections in other parts of the world, such as Africa or Asia.

"Based on the observation that [HBV] genotypes go extinct and can be created by recombination, the ancient sequence data show that the diversity that we observe today is only a subset of the diversity that has ever existed," the authors wrote. "These data support a scenario in which all present-day HBV diversity arose only after the split of the Old World and New World genotypes."

Willerslev said the availability of ancient HBV sequences "allows you to address very fundamental questions about the evolution and development of this disease." More broadly, he noted, the new data "provides a catalog" of past mutations in the HBV genome. Because it is conceivable that some of those mutations may return at some point, he added, and the sequences serve as "not a full catalog, but at least a start of a catalog of possible variances that we may see in the future."

A technique to manipulate electrons with light could bring quantum computing up to room temperature.

A team of researchers in Germany and at the University of Michigan have demonstrated how infrared laser pulses can shift electrons between two different states, the classic 1 and 0, in a thin sheet of semiconductor. "Ordinary electronics are in the range of gigahertz, one billion operations per second. This method is a million times faster," said Mackillo Kira, U-M professor of electrical engineering and computer science.

He led the theoretical part of the study, to be published in the journal Nature, collaborating with physicists at the University of Marburg in Germany. The experiment was done at the University of Regensburg in Germany.

Quantum computing could solve problems that take too long on conventional computers, advancing areas such as artificial intelligence, weather forecasting and drug design. Quantum computers get their power from the way that their quantum-mechanical bits, or qubits, aren't merely 1s or 0s, but they can be mixtures— known as superpositions—of these states.

"In a classical computer, each bit configuration must be stored and processed one by one while a set of qubits can ideally store and process all configurations with one run," Kira said.

Huber's team prodded electrons into these states with quick pulses of infrared light, lasting just a few femtoseconds (quintillionths of a second). The initial pulse has its own spin, known as circular polarization, that sends electrons into one pseudospin state. Then, pulses of light that don't have a spin (linearly polarized) can push the electrons from one pseudospin to the other—and back again.

By treating these states as ordinary 1 and 0, it could be possible to create a new kind of "lightwave" computer with the million-times-faster clock speeds that Kira mentioned. The first challenge along this route will be to use a train of laser pulses to "flip" the pseudospins at will. But the electrons can also form superposition states between the two pseudospins. With a series of pulses, it should be possible to carry out calculations until the electrons fall out of their coherent state. The team showed that they could flip a qubit quickly enough to execute a string of operations—basically, it's fast enough to work in a quantum processor.

Moreover, the electrons are constantly sending out light that makes it easy to read a qubit without disturbing its delicate quantum state. Clockwise circular polarization indicates one pseudospin state, counterclockwise the other.

The next steps toward quantum computing will be to get two qubits going at once, near enough to one another that they interact. This could involve stacking the flat sheets of semiconductor or using nanostructuring techniques to fence off qubits within a single sheet.

MD Anderson researchers use supercomputers at the Texas Advanced Computing Center to develop, test treatment target identification tool for head and neck cancers.

Before performing radiation therapy, radiation oncologists first carefully review medical images of the patient to identify the gross tumor volume, the observable portion of the disease. They then design patient-specific clinical target volumes that include surrounding tissues, since these regions can hide cancerous cells and provide pathways for metastasis.

Known as contouring, this process establishes how much radiation a patient will receive and how it will be delivered. In the case of head and neck cancer, this is a particularly sensitive task due to the presence of vulnerable tissues in the vicinity.

Though it may sound straightforward, contouring clinical target volumes is quite subjective. A recent study from Utrecht University found wide variability in how trained physicians contoured the same patient's computed tomography (CT) scan, leading some doctors to suggest high-risk clinical target volumes eight times larger than their colleagues. This inter-physician variability is a problem for patients, who may be over- or under-dosed based on the doctor they work with. It is also a problem for determining best practices, so standards of care can emerge.

Recently, Carlos Cardenas, a graduate research assistant and PhD candidate at The University of Texas MD Anderson Cancer Center in Houston, Texas, and a team of researchers at MD Anderson, working under the supervision of Laurence Court with support from the National Institutes of Health, developed a new method for automating the contouring of high-risk clinical target volumes using artificial intelligence and deep neural networks.

They report their results in the June 2018 issue of the International Journal of Radiation Oncology*Biology*Physics.

Pioneering new research from the University of Exeter, UK, has revealed when the 11-year solar cycle is in its ‘weaker’ phase, there are warm spells across the Arctic in winter, as well as heavy snowfall across Eurasia.

Dr. Indrani Roy, a researcher at the College of Engineering, Mathematics and Physical Sciences at the University of Exeter, evaluated the impact of the 11-year solar cycle — measured in terms of solar sunspot number (SSN) — as a driving factor to modulate Arctic and surrounding climate. “We explored how the solar cycle — a periodic change in the Sun’s activity including changes in the levels of solar UV radiation and changes in the SSNs — can be linked with the Polar vortex and Arctic Oscillation phenomenon, which affects winter Arctic and Eurasian climate,” Dr. Roy explained. “It subsequently can influence weather conditions in Europe, including the UK, Scandinavia and Asia,” she said.

The study observed that during periods when the winter SSN falls below average, the Arctic warming extends from the lower troposphere to high up in the upper stratosphere. On the other hand there is a cooling when SSN is above average. “In spite of all other influences and complexities, it is still possible to segregate a strong influence from the Sun,” Dr. Roy noted. “There are reductions of sea-ice in the Arctic and a growth in the Eurasian sector is observed in recent winters. This study shows those trends are related and current weaker solar cycle is contributing to that.”

A molecule containing genetic instructions passed on from the mother to the egg must be present for the fertilized egg to survive and develop into a normal embryo, according to results of a zebrafish study funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health. The study appears in a recent issue of eLife and was conducted by researchers from Princeton University.

The researchers found that if zebrafish eggs are deprived of a specific messenger RNA molecule passed on from the mother, they will develop abnormally after fertilization and soon die. The RNA molecule contains the instructions to make a protein known as growth differentiation factor-3 (GDF3). Although they can make GDF3 on their own, fertilized zebrafish eggs deprived of the messenger RNA molecule from their mothers cannot produce two of the three major cell types the embryo needs to develop.

The findings provide insight into the early stages of embryonic development and could ultimately yield information for understanding and treating a class of birth defects relating to left-right development in the embryo, including heart malformations present at birth.

Messenger RNA is a molecule that carries the instructions from a length of DNA out of the nucleus and into the cell, where it is translated into a protein. Previous studies have shown that messenger RNA needed to make GDF3 are deposited in the cytoplasm—fluid surrounding the nucleus—in the egg cell. A wealth of papers have been written on how this RNA is localized and regulated, but it was never clear what its protein actually does in the developing embryo, said the study’s senior author Rebecca Burdine, Ph.D., associate professor of molecular biology at Princeton University.

Researchers developed zebrafish embryos lacking the gene for GDF3. These embryos developed normally and grew into adults. However, the adult females could not provide GDF3 messenger RNA to their own eggs, and their embryos failed to develop and soon died. Deprived of maternal GDF3 messenger RNA, the embryos could not produce cells for two embryonic structures essential for further development: the mesoderm and the endoderm. 

However, if fertilized eggs from these adult females received injections of maternal GDF3 RNA, the resulting embryos would continue to develop. When the researchers provided the embryos with just enough GDF3 protein to develop the mesoderm and endoderm before eliminating their supply of the protein, the embryos developed abnormal Kupffer’s vesicles—the cell structure that establishes the differences between the left and right sides of the body. These embryos later developed hearts that were abnormally positioned.

Although PARP inhibitors (PARPi) target homologous recombination defective tumors, drug resistance frequently emerges, often via poorly understood mechanisms. Here, using genome-wide and high-density CRISPR-Cas9 “tag-mutate-enrich” mutagenesis screens, a group of scientists identify close to full-length mutant forms of PARP1 that cause in vitro and in vivo PARPi resistance. Mutations both within and outside of the PARP1 DNA-binding zinc-finger domains cause PARPi resistance and alter PARP1 trapping, as does a PARP1 mutation found in a clinical case of PARPi resistance. This reinforces the importance of trapped PARP1 as a cytotoxic DNA lesion and suggests that PARP1 intramolecular interactions might influence PARPi-mediated cytotoxicity. PARP1mutations are also tolerated in cells with a pathogenic BRCA1 mutation where they result in distinct sensitivities to chemotherapeutic drugs compared to other mechanisms of PARPi resistance (BRCA1 reversion,53BP1, REV7 (MAD2L2) mutation), suggesting that the underlying mechanism of PARPi resistance that emerges could influence the success of subsequent therapies.

Scientists have inserted fungus genes into a yeast cell to make it produce penicillin molecules.

Baker’s yeast is easy to genetically engineer. Scientists can simply insert DNA from bacteria and fungi into yeast to carry out experiments, offering a viable new host for antibiotic production research. The rise of synthetic biology methods for yeast will allow researchers to make and test many new gene combinations that could produce a whole new range of new antibiotics.

However, the authors are keen to point out that the research is still in its early stages. While this approach does show promise, they have so far produced non-ribosomal peptide antibiotic penicillin in small quantities. More research needs to be done to see if it can be adapted to finding other compounds and to get production up to commercially viable quantities.

Dr Tom Ellis, from the Centre for Synthetic Biology at Imperial College London, explains: “Humans have been experimenting with yeast for thousands of years. From brewing beer to getting our bread to rise, and more recently for making compounds like anti-malarial drugs, yeast is the microscopic workhorse behind many processes. The rise of drug-resistant superbugs has brought a real urgency to our search for new antibiotics. Our experiments show that yeast can be engineered to produce a well-known antibiotic. This opens up the possibility of using yeast to explore the largely untapped treasure trove of compounds in the nonribosomal peptide family to develop a new generation of antibiotics and anti-inflammatories.”

Previously, scientists have demonstrated that they could re-engineer a different yeast to make penicillin. However, that species of yeast is not as well understood or amenable to genetic manipulation compared to baker’s yeast, used by the authors in today’s study, making it less suitable for the development of novel antibiotics using synthetic biology.

RoboFly—a design based on the RoboBee flapping-wing microrobot from Harvard’s MicroRobotics Lab—is about the size of a bumblebee, and weighs just 190 milligrams (a bit more than a toothpick). It’s powered by an infrared laser aimed at that tiny little photovoltaic cell, which can harvest the 250 mW required to get the robot airborne. In the video, the laser doesn’t track the robot, so as soon as the solar cell moves out of the beam, it loses power and the robot stops flying. 

While delivering the power is a significant part of the challenge, developing the electronics necessary to turn that power into flight is the initial focus of the University of Washington group, which included Johannes James, Vikram Iyer, Yogesh Chukewad, Shyamnath Gollakota, and Sawyer B. Fuller. The wings are driven by two piezoelectric actuators, which require around 250 volts to maximize power density. The photovoltaic cell outputs just 7 volts, so the researchers had to custom design a boost converter to drive the wings, and add a microcontroller to control them. They managed to cram both of these things into an electronics package that weighs under 100 mg, enabling the robot to function completely untethered.

It’s tempting to watch the video and be like, “Uh, that’s it?” But note that the primary thing that needs to happen for the robot to achieve longer flights is for the laser to track the photovoltaic cell so that it can provide power continuously, and this is a problem that other researchers have worked on before with some success. The UW team has been able to power the robot at ranges of up to 1.23 meters indoors, and with a higher output laser (or one that can focus a bit better), they expect that a range of some tens of meters shouldn’t be much of a problem. Ultimately, a RoboFly could be controlled by a ceiling-mounted laser that tracks it wherever it goes, or even lasers mounted on moving vehicles (or other robots) that can follow the RoboFly around and provide power to it indefinitely.

A solid can serve as a medium for heat and sound wave interactions just like a fluid does for thermoacoustic engines and refrigerators – resulting in leak-free machines that can stay operating longer.

Leaky systems have limited how engineers design thermoacoustic devices that rely on the interplay between temperature oscillations and sound waves. Researchers at Purdue and the University of Notre Dame have demonstrated for the first time that thermoacoustics could theoretically occur in solids as well as fluids, recently presenting their findings at the 175th Meeting of the Acoustical Society of America.

“Although still in its infancy, this technology could be particularly effective in harsh environments, such as outer space, where strong temperature variations are freely available and when system failures would endanger the overall mission,” said Fabio Semperlotti, Purdue assistant professor of mechanical engineering.

Thermoacoustics has been an established and well-studied phenomenon in fluids – whether as a gas or liquid – for centuries. “Applying heat to a fluid enclosed in a duct or cavity will cause the spontaneous generation of sound waves propagating in the fluid itself,” said Carlo Scalo, an assistant professor of mechanical engineering at Purdue. “This results in so-called singing pipes, or thermoacoustics machines.”

While fluids have been historically used for these systems, the extra step of building something to contain the fluids and prevent leaks is cumbersome. This led the researchers to consider solids as a replacement. “Properties of solids are more controllable, which could make them potentially better suited to these applications than fluids. We needed to first verify that this phenomenon could theoretically exist in solid media,” said Haitian Hao, Purdue graduate research assistant in mechanical engineering.

Thermoacoustics enables either waste heat or mechanical vibrations to be converted into other useful forms of energy. For refrigerators, sound waves generate a temperature gradient of hot and cold. The vibrating motion makes cold areas colder and hot areas hotter. Engines use an opposite process: a temperature gradient provided by waste heat leads to mechanical vibrations.

DNA mutations driving cancer development are caused by different mechanisms, each of them leaving behind specific patterns, or "scars" in the genome. Using CRISPR-Cas9 technology, researchers at CeMM and the Wellcome Trust Sanger Institute at Cambridge, UK were able to show for the first time in cell culture that specific genetic alterations indeed lead to the predicted pattern of mutational signatures observed in human cancers. The results were published in Nature Communications.

When a cell develops into a tumor, something has gone terribly wrong: the uncontrolled growth, invasion of nearby tissues and finally metastasis are the result of many consecutive DNA mutations. Such an accumulation of demolished genetic material often derives from initial environmental exposures, enzymatic activities or defects in DNA replication or DNA repair mechanisms. Each of those initial mutagenic conditions creates their own pattern of DNA damage called mutational signature. Deciphering them could theoretically allow us to trace back the initial cause of a tumor, profile its properties and help find a therapeutic strategy.

However, reading those mutational signatures in tumor samples is a difficult task, as the large amount of mutations that a patient acquires during its lifetime create a noisy and uncontrolled system -- even the best clinical data will, at most, provide only associations. Therefore, the group of Joanna Loizou, Principal Investigator at the CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, in collaboration with researchers from the Wellcome Trust Sanger Institute, developed an experimental setup to validate the concept of mutational signatures in cell culture.

In special human cell lines, optimized for genome editing, the researchers destroyed nine different genes -- one gene per cell line -- for DNA repair using CRISPR-Cas9 technology. Subsequently, they cultivated single cells from each of those nine experiments and allowed them to proliferate for one month. Eventually, the scientists analyzed the entirety of mutations that accumulated over this time period in the cell line deriving from the single progenitor that lacks a specific DNA repair gene. With specially developed computational methods, they were able to find the genomic scars that a missing DNA repair gene left in the genome of the affected cells -- they were almost identical to mutational signatures found in cancer cells.

"Our results validate mutational signatures across all classes of mutations," Joanna Loizou summarizes the findings. "For the first time, this theoretical concept was confirmed in a highly controlled experimental setup." However, a single gene defect is not restricted to only one mutational signature, Loizou adds: "We found that some defects in DNA repair genes engender multiple mutational signatures of different classes." The converse is also true, as Michel Owusu, PhD Student in Loizou's laboratory and co-first author of the paper explains: "A mutational signature may not necessarily reflect a defect of one gene, as it could also arise through the malfunctioning of another related gene involved in the affected DNA repair mechanism."

The occasional decay of neutrons into dark matter particles could solve a long-standing discrepancy in neutron decay experiments.

Neutrons decay within about 14.5 min, but their exact lifetime is still debated, as two types of neutron decay experiments give conflicting results. The source for this discrepancy could be some unidentified systematic error. But another possibility is that neutrons decay into invisible particles that constitute the missing dark matter. This new hypothesis has sparked significant interest, with one group of experimenters already putting the idea to the test. The results of that effort constrain one version of the theory, but other scenarios remain viable.

Outside the nucleus, a neutron decays into a proton, an electron, and a neutrino. Studies of this decay process come in two varieties, which go by the names “bottle” and “beam.” In a bottle experiment, researchers place a set of ultracold neutrons in a container and count how many remain after a certain time has passed. In a beam experiment, researchers observe a stream of neutrons and count the number of protons created from decays. The beam neutron lifetime is roughly 9 s longer than the bottle value.

Bartosz Fornal and Benjamín Grinstein from the University of California, San Diego, propose a solution to this discrepancy that assumes neutrons decay 1% of the time into dark matter particles. Because beam experiments would not detect these decays, their inferred neutron lifetime would be longer than the actual value. Fornal and Grinstein investigate several scenarios with neutrons decaying into different combinations of dark matter and visible particles. In one of these scenarios, neutron dark decays are accompanied by a gamma ray. Inspired by this possibility, Christopher Morris from Los Alamos National Laboratory, New Mexico, and colleagues monitored the gamma-ray emission from a bottle of ultracold neutrons. They didn’t find any signal, appearing to rule out this proposed decay channel in the photon energy range of 782 to 1664 keV. But other decay scenarios—that produce lower energy gammas or no gammas at all—are still possible and might be tested by looking for anomalies in nuclear decays.

In addition to the plane of the Milky Way, observations also cover a region around the Galactic Center, capturing data on one of the densest neighborhoods in the galaxy. This region contains a supermassive black hole, surrounded by tens of millions of stars within just a few light years' distance of the center. The chaotic environment at the very center of the galaxy is probably not well suited to the emergence of life as we know it, but the region surveyed by Breakthrough Listen covers a huge slice of the Milky Way, containing tens of billions of stars, including many that lie between us and the galaxy's heart

The new digital instrumentation, installed by scientists and engineers from the University of California, Berkeley SETI Research Center (BSRC), expands the existing Breakthrough Listen back-end so that it can now handle 130 gigabits per second—thousands of times the bandwidth of even a fast home Internet connection. This represents over 100 million radio channels scanned for each of the 13 beams—one of the most comprehensive SETI (search for extraterrestrial intelligence) experiments carried out to date.

The survey commits the Parkes telescope to 1500 hours of observations in 2018, resulting in raw data volumes totaling almost 100 petabytes. Reduced data products for all observations will be archived for the long term, in addition to 1 PB of raw data products to be archived at the Pawsey supercomputing center in Perth. Data will then be searched for signals that have indications of artificial origin. The vast majority of such signals come from human-generated radio frequency interference (RFI) - satellites, airplanes, cellphones, and the like—and discriminating between RFI and signals of interest is the major challenge facing any SETI search. In addition to the search pipeline implemented by the BSRC team, Listen invites all those with the relevant technical expertise to contribute to developing signal detection and classification algorithms.

There's enough potential wind energy moving across the Earth's oceans to power all of humanity, according to a new study. But, the researchers warn, trying to harness it would be a bad idea.

There is, of course, lots of wind over the Earth's land. There's so much wind that it's not uncommon for surplus wind energy to overwhelm the infrastructure built to carry it, as happened in Texas last year. But the land is no match for the sea in this regard. On land, wind gets diluted through impediments both natural and man-made, from mountains to skyscrapers. The oceans have no such monuments, which the authors of the study, Anna Possnera and Ken Caldeira of Stanford, say could make a huge difference.

"Mean surface wind speeds are, on average, 70% higher than on land," they say, "and could, therefore, prove to be a viable source for wind energy technologies."

What sort of difference would that make? "Even in the relative calm of summer," Possnera and Caldeira conclude, "the upper geophysical limit on sustained wind power in the North Atlantic alone could be sufficient to supply all of Europe's electricity. On an annual mean basis, the wind power available in the North Atlantic could be sufficient to power the world."

However, there would need to be a lot of wind turbines put in place in the ocean for this project to happen. So much so that humanity would be creating the same sort of impediments that weaken wind on land. That would prevent wind from chilling the icy poles, giving us the same problem renewables were supposed to solve: melting ice caps, rising oceans.

But just because humanity can't take all of its energy from the North Atlantic doesn't mean that the study isn't tremendously useful. In attempting to grasp the geophysical limit of wind power, Possnera and Caldeira show how dramatically we could scale up. The United States, for example, only opened its first offshore wind farm last year.

The chance of accidentally destroying the Earth with too much wind energy is science fiction, the opportunity to radically help the planet and get cheap power to boot is stone-cold fact.

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Experiments with ultra-cold atoms at the TU Wien have shown surprising results: coupled atom clouds synchronize within milliseconds. This effect cannot be explained by standard theories.

When atoms are cooled down to almost zero temperature, their properties change completely. They can turn into a Bose-Einstein-Condensate, an ultra-cold state of matter, in which the particles lose their individuality and can only be described collectively – as one single quantum object.

At TU Wien (Vienna), clouds of ultra-cold atoms have been studied for years. They are a perfect model system to study fundamental questions of many-particle quantum physics. Now the research team of Professor Jörg Schmiedmayer (Institute of Atomic and Subatomic Physics, TU Wien) has found remarkable results which cannot be explained by any of the existing theories. When two ultra-cold quantum gases are coupled, they can synchronize spontaneously, oscillating in perfect unison after just a few milliseconds. This means that textbook theories about Bose-Einstein-Condensates have to be revisited. The results have now been published in the journal Physical Review Letters.

Looking for an Unknown Mechanism

"In the process of de-synchronizing the clocks, we bring the system out of equilibrium", says Marine Pigneur, part of the discovery team. "Most theories so far successfully describe the coupling of Bose-Einstein-Condensates in equilibrium, but they are insufficient to describe the out of equilibrium situation and the synchronization we observe." The fact that the "quantum rhythms" of the two atom clouds are exactly the same after only a few milliseconds implies the existence of a mechanism that dissipates energy. As the system is isolated from its environment, energy cannot be dissipated but only transferred. "The coupling as accounted in textbooks theories cannot transfer energy as strongly and quickly as we observe. So either these theories are missing something – or they are just wrong. It means that it is our understanding of the interaction between the atoms itself which must be modified."

With this surprising finding, the research team hopes to stimulate further research in this area. "After all, the behaviour of many-body quantum systems out of equilibrium is one of the big unsolved problems of modern physics", says Jörg Schmiedmayer. "It connects to many fundamental questions – from the state of the early universe right after the big bang to the question why strange quantum effects can only be observed on a tiny scale, whereas larger objects obey the laws of classical physics."

Animation in film and video games is hard to make realistic: each action typically requires creating a separate controller, while deep reinforcement learning has yet to generate realistic human or animal motion. Computer scientists have now developed an algorithm that uses reinforcement learning to generate realistic simulations that can even recover realistically, after tripping, for example. The same algorithm works for 25 acrobatic and dance tricks, with one month of learning per skill.

It's still easy to tell computer-simulated motions from the real thing -- on the big screen or in video games, simulated humans and animals often move clumsily, without the rhythm and fluidity of their real-world counterparts.

But that's changing. University of California, Berkeley researchers have now made a major advance in realistic computer animation, using deep reinforcement learning to recreate natural motions, even for acrobatic feats like break dancing and martial arts. The simulated characters can also respond naturally to changes in the environment, such as recovering from tripping or being pelted by projectiles.

"This is actually a pretty big leap from what has been done with deep learning and animation. In the past, a lot of work has gone into simulating natural motions, but these physics-based methods tend to be very specialized; they're not general methods that can handle a large variety of skills," said UC Berkeley graduate student Xue Bin "Jason" Peng. Each activity or task typically requires its own custom-designed controller.

"We developed more capable agents that behave in a natural manner," he said. "If you compare our results to motion-capture recorded from humans, we are getting to the point where it is pretty difficult to distinguish the two, to tell what is simulation and what is real. We're moving toward a virtual stuntman."

The work could also inspire the development of more dynamic motor skills for robots. A paper describing the development has been conditionally accepted for presentation at the 2018 SIGGRAPH conference in August in Vancouver, Canada, and was posted online April 10. Peng's colleagues in the Department of Electrical Engineering and Computer Sciences are professor Pieter Abbeel and assistant professor Sergey Levine, along with Michiel van de Panne of the University of British Columbia.

Quantum physicists are about to get their own playground in space. NASA’s Cold Atom Laboratory, scheduled to launch to the International Space Station on 20 May, is set to be the coldest place in the known Universe. Researchers will use the lab to probe quantum phenomena that would be impossible to observe on Earth.

The US$83-million mission will be used to study quantum mechanics on the macroscopic scale by making a state of matter known as a Bose–Einstein condensate (BEC). These are clouds of hundreds of thousands of atoms that, when chilled to just above absolute zero, behave as waves that synchronize into a single quantum object. “Just being able to do these experiments in space I think is a huge accomplishment,” says Kamal Oudrhiri, mission manager at the Jet Propulsion Laboratory (JPL) in Pasadena, California.

On Earth, gravitational forces usually disperse these condensates within a few seconds. The closest that BECs have come to being in space-like conditions is during brief stints in a research rocket, or falling from a drop tower over 9 seconds. But, floating on the space station, they should be able to exist for at least 10 seconds. That’s long enough for them to be cooled to record-low temperatures — perhaps as little as 20 trillionths of a degree above absolute zero. That would be the coldest known temperature in the Universe, says Oudrhiri. Colder and long-lasting condensates will “push the frontiers of studying fundamental physics”, says Gretchen Campbell, an atomic physicist at the US National Institute of Standards and Technology in Gaithersburg, Maryland. “It’s something people have hoped for for almost 15 years.”