Science

Two moons in the outer solar system—Jupiter’s Europa and Saturn’s Enceladus—are becoming the undisputed top targets in the search for life elsewhere in the solar system, scientists and NASA officials said at a press conference Thursday. Beneath their icy crusts both moons have deep, global oceans of liquid water, kept warm by tidal tugs from the gas-giant planets they orbit. Whether anything swims in those oceans remains unknown—but perhaps not for long. At Enceladus, NASA’s Cassini spacecraft has discovered molecular hydrogen—a potential foodstuff for bacteria and a sign of hydrothermal activity—within plumes of water vapor venting from the ocean into space through cracks in the moon’s surface ice. At Europa, earthbound telescopes have spied signs of similar plumes, tracing one that seems to repeat—an “Old Faithful” of the outer solar system—to a mysterious thermal anomaly on the moon’s surface. Both findings boost the case for sending future life-finding missions to each moon as part of …

When the now-famous neurological patient Henry Molaison had his brain’s hippocampus surgically sectioned to treat seizures in 1953, science’s understanding of memory inadvertently received perhaps its biggest boost ever. Molaison lost the ability to form new memories of events, and his recollection of anything that had happened during the preceding year was severely impaired. Other types of memory such as learning physical skills were unaffected, suggesting the hippocampus specifically handles the recall of events—known as “episodic” memories. Further research on other patients with hippocampal damage confirmed recent memories are more impaired than distant ones. It appears the hippocampus provides temporary storage for new information whereas other areas may handle long-term memory. Events that we are later able to remember appear to be channeled for more permanent storage in the cortex (the outer layers of the brain responsible for higher functions such as planning and problem-solving). In the cortex these memories form gradually, becoming integrated with …

U-tube: the glass tube and piezoelectric speaker A $12 device that can measure the mass of microgram-sized objects in fluid has been developed by researchers in the US. The sensor is driven by a piezoelectric speaker and measures the change in the resonant frequency of a glass tube as the object passes through it. The team used the device to measure mass changes in several biological samples and says that the sensor has applications in a wide range of fields, such as developmental biology, toxicology, materials science and plant science. Mass is an important physical measurement that can provide crucial information about the nature of an object. However, weighing microgram-sized biological samples such as embryos in liquid, can be very tricky indeed. While mass measurements can offer valuable insights into the biological state and health of such specimens, they cannot be easily made with standard laboratory equipment. Nanogram resolution To tackle this shortcoming, William Grover …

Genetic testing company 23AndMe is back with a controversial new offering, after the U.S. Food and Drug Administration on Thursday green-lighted the company’s request to market a fresh batch of direct-to-consumer tests. Soon, with a simple saliva swab dropped in the mail, customers will be able to get answers about their genetic risk for developing 10 maladies—including Parkinson’s disease and late-onset Alzheimer’s. The FDA approval will likely reignite a long-simmering debate about when and how such tests should be used. Even when there are strong links between certain gene variants and medical conditions, genetic information often remains difficult to interpret. It must be balanced against other factors including health status, lifestyle and environmental influences, which could sharpen or weaken risk. If disease risk news is delivered at home—without a genetic counselor or doctor on hand to offer context—many geneticists fear it can lead to unnecessary stress, confusion and misunderstandings. Against that backdrop, the FDA’s decision …

For the past five decades pharmaceutical drugs like levodopa have been the gold standard for treating Parkinson’s disease. These medications alleviate motor symptoms of the disease, but none of them can cure it. Patients with Parkinson’s continue to lose dopamine neurons critical to the motor control centers of the brain. Eventually the drugs become ineffective and patients’ tremors get worse. They experience a loss of balance and a debilitating stiffness takes over their legs. To replace the lost dopamine neurons, scientists have begun investigating stem cell therapy as a potential treatment or even a cure. But embryonic cells and adult stem cells have proved difficult to harness and transplant into the brain. Now a study from the Karolinska Institute in Stockholm shows it is possible to coax the brain’s own astrocytes—cells that typically support and nurture neurons—into producing a new generation of dopamine neurons. The reprogrammed cells display several of the properties and functions of …

Pres. Donald Trump issued a major executive order last week that, if successful, could undercut the nation’s fight against global warming. In particular, the order kicks off an attempt to dismantle the Clean Power Plan, which regulates carbon emissions from the power sector. While Trump’s move represents a big blow to U.S. climate efforts, the renowned scientist James Hansen sees a different—and, he argues, better—way forward on global warming. “The problem is the Clean Power Plan is really not that effective,” says Hansen, former director of NASA Goddard Institute for Space Studies and adjunct professor at Columbia University’s Earth Institute, who brought climate change to the U.S. public’s attention in his famed 1988 congressional testimony. “It’s a tragedy that [the Obama administration] continued to pursue a regulatory approach.” The solution Hansen believes will work best is one recently advocated by a group of Republican statesmen: a “carbon fee and dividend.” Although it is not a …

Squeezed spins: illustration of atoms in the optical trap Bell correlations – a hallmark of an entangled quantum system – have been spotted in an ensemble of 500,000 rubidium-87 atoms. The atoms were prepared in spin-squeezed states by physicists at Stanford University in the US and the correlations measured to a whopping statistical significance of 124σ. In quantum mechanics, entangled particles have much stronger correlations than are allowed in classical physics – a property that can be exploited in quantum technologies including cryptography. In 1964 the physicist John Bell famously calculated an upper limit on how strong these correlations could be if they were caused by classical physics alone – what has become known as Bell’s inequality. Correlations stronger than this limit, Bell reasoned, could occur only if the particles are entangled. In this latest work, Onur Hosten, Mark Kasevich and colleagues have measured these strong Bell correlations in an ensemble of 500,000 cold rubidium-87 atoms that …

People cherish diamonds for their beauty and the sense of status and permanence they convey to the wearer, but someday soon these most precious of stones may serve an even more practical purpose than filling out engagement rings and anniversary pendants: protecting smartphone displays from the chips and spider web–like cracks that develop after countless drops and hours of tapping and swiping. Unlike the nuggets mined from deep in Earth’s crust, display-screen diamonds would be grown in the lab of AKHAN Semiconductor, a company developing ways to use synthetic diamonds to enhance electronics. By the end of the year AKHAN plans to begin making glass smartphone screens coated with a microns-thick layer of diamond, which the company says will be more scratch-resistant and less prone to shattering. The company will not say, however, which smartphone makers might use its Miraj Diamond Glass or how it would keep the cost of those screens affordable. Regardless of …

What do you do when your spacecraft runs out of fuel after a 20-year journey? Send it barreling into the planet it has studied for more than a decade in a final blaze of glory, of course. The Cassini mission launched on October 15, 1997. Seven years later the spacecraft entered Saturn’s orbit. Since then it has made some incredible discoveries at the solar system’s second-largest world, including finding liquid hydrocarbon lakes on Titan, Saturn’s largest moon, as well as spying plumes of water ice and particles jetting from a subsurface ocean within another moon, Enceladus. Now the spacecraft is nearing the end of its journey. Speaking from the Jet Propulsion Laboratory (JPL) on Tuesday, a panel of Cassini scientists discussed the mission’s dramatic conclusion. In November, to prepare for the end, Cassini moved closer to Saturn, tilting its orbit from nearly equatorial to circling the planet from pole to pole. Images from earlier this year …

Molecules on the move: illustration of soliton molecules Solitons – non-dispersive wavepackets – are key features of nonlinear optics and other nonlinear wave systems. Theoreticians have long predicted that solitons can bind together to form “molecules” – and experiments have confirmed this in simple cases. Now, researchers in Germany and the US have analysed the spectra of soliton molecules multiple times as they ricocheted between the mirrors of a laser cavity – gaining remarkable insights into the dynamics of pairs and even triplets of solitons. Light in optical fibres normally behaves as the linear sum of its frequency components. Laser pulses therefore gradually spread out as different frequencies travel at different speeds in a fibre. At high powers, however, the refractive index of glass fibre becomes nonlinear, so higher-intensity pulses propagate more slowly. This acts to push pulses together and, under specific conditions, the two effects can balance each other to create solitons – waves …

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