Scientists have discovered how cells from the fetus could activate maternal natural killer cells during early pregnancy, helping to demystify the poorly understood mechanisms that govern immune cells at the maternal-fetal interface.

Learn more in Science Signaling.

A fetal cell antigen interacts with a natural killer cell receptor to induce antiviral gene expression.

Researchers at the Institute for Molecular Science (NINS, Japan) and SOKENDAI have demonstrated a more than 2000% voltage-induced enhancement of near-field nonlinear optical responses. To achieve this giant modulation, they focused on an angstrom-scale gap formed between a metallic tip and substrate in a scanning tunneling microscope (STM), which can strongly confine and enhance light intensity through plasmon excitation. The paper is published in the journal Nature Communications.

The researchers discovered that when the voltage across the junction was varied within ±1 V, the intensity of second-harmonic generation (SHG) changed quadratically with voltage and exhibited giant modulation with a depth of ~2000%/V. This represents a more than two-orders-of-magnitude improvement over previous electroplasmonic systems.

Moreover, similar giant electrical modulation was also observed for sum-frequency generation, a nonlinear optical process that upconverts mid-infrared light into visible or near-infrared light. This demonstrates that the newly discovered electrical modulation mechanism is applicable to the broad spectral range, not limited to a specific optical wavelength or nonlinear optical process.

An international research team led by the University of Bremen has detected chlorofluorocarbons (CFCs) in Earth’s atmosphere for the first time in historical measurements from 1951—20 years earlier than previously known. This surprising glimpse into the past was made possible by analyzing historical measurement data from the Jungfraujoch research station in the Swiss Alps. The study has now been published in Geophysical Research Letters.

“This discovery provides quantitative data for the concentration of a CFC for the year 1951,” explains Professor Justus Notholt from the Institute of Environmental Physics at the University of Bremen. “Without the archived measurements from the Jungfraujoch station, this unique look into the past would have been impossible.”

Hidden mega-structures deep inside Earth may have been quietly steering our planet’s magnetic field—and rewriting what we thought we knew about Earth’s past.

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Time is almost up on the way we track each second of the day, with optical atomic clocks set to redefine the way the world measures one second in the near future. Researchers from Adelaide University worked with the National Institute of Standards and Technology (NIST) in the United States and the National Physical Laboratory (NPL) in the United Kingdom to review the future of the next generation of timekeeping.

They found that development is happening at such a fast rate that optical atomic clocks are well positioned to become the gold standard for timekeeping within the next few years, provided some technical challenges can be addressed.

“Optica l atomic clocks have advanced rapidly over the past decade, to the point where they are now one of the most precise measurement tools ever built. They’re more accurate than the best microwave atomic clocks and can even work outside the lab—this is a place that conventional atomic clocks have trouble venturing,” said co-author Professor Andre Luiten from Adelaide University’s Institute for Photonics and Advanced Sensing.