Phys.org January 25, 2021 Autofocusing is a critical step for high-quality microscopic imaging of specimens, especially for measurements that extend over time covering large fields of view. Hardware-based optical autofocusing methods rely on additional distance sensors that are integrated with a microscopy system; Algorithmic autofocusing methods require axial scanning through the sample volume, leading to longer imaging times, which might also introduce phototoxicity and photobleaching on the sample. Researchers at UCLA have demonstrated a deep learning-based offline autofocusing method, termed Deep-R, that is trained to rapidly and blindly autofocus a single-shot microscopy image of a specimen that is acquired at […]
Author Archives: Hema Viswanath
Defects may help scientists understand the exotic physics of topology
Science Daily January 22, 2021 Researchers at the University of Illinois engineered metamaterials to include defects to show that defects and structural deformations can provide insights into a real material’s hidden topological features. They experimentally demonstrated that disclination defects can robustly trap fractional charges in topological crystalline insulators (TCI) metamaterials, and the trapped charge can indicate non-trivial, higher-order crystalline topology even in the absence of any spectral signatures. They uncovered a connection between the trapped charge and the existence of topological bound states localized at these defects. By testing the robustness of these topological features when the protective crystalline symmetry […]
“Liquid” machine-learning system adapts to changing conditions
MIT News January 28, 2021 An international team of researchers (USA – MIT, Austria) designed a neural network that can adapt to the variability of real-world systems. They took inspiration from C.elegans which has only 302 neurons in its nervous system, yet it can generate unexpectedly complex dynamics. The equations they used to structure their neural network allowed the parameters to change over time based on the results of a nested set of differential equations. Most neural networks’ behavior is fixed after the training phase. The fluidity of their “liquid” network makes it more resilient to unexpected or noisy data and […]
Long-distance and secure quantum key distribution (QKD) over a free-space channel
Phys.org January 25, 2021 Measurement-device-independent quantum key distribution (MDI-QKD) protocol can help in closing all loopholes on detection at once. It has only been successfully implemented using fiber optics. To implement the protocol across free-space channels two main challenges need to be addressed. One is to reduce the gap between theory and practice of QKD, and the other one is to extend the distance of QKD. Researchers in China have developed a robust adaptive optics system – high-precision time synchronization and frequency locking between independent photon sources located far apart to realize free-space MDI-QKD over a 19.2-km urban atmospheric channel. […]
Microbes fueled by wind-blown mineral dust melt the Greenland ice sheet
Science Daily January 25, 2021 Melting of the Greenland Ice Sheet is a leading cause of land-ice mass loss and cryosphere-attributed sea level rise. Blooms of pigmented glacier ice algae lower ice albedo and accelerate surface melting in the ice sheet’s southwest sector. Although glacier ice algae cause up to 13% of the surface melting in this region, the controls on bloom development remain poorly understood. An international team of researchers (US, Canada, Germany, Denmark) has shown a direct link between mineral phosphorus in surface ice and glacier ice algae biomass through the quantification of solid and fluid phase phosphorus […]
Optimal information about the invisible
Phys.org January 25, 2021 If the laser beam is deflected, scattered, and refracted, often it impossible to obtain useful data from the measurement. According to an international team of researchers (the Netherlands, Austria) if you know exactly what the disturbing environment is doing to the light beam, you can reverse the situation: Then it is possible to create a complicated wave pattern instead of the simple, straight laser beam, which gets transformed into exactly the desired shape due to the disturbances and hits right where it can deliver the best result. It is enough to first send a set of […]
Rapid Identification of Ricin in Serum Samples Using LC–MS/MS
Global Biodefense January 23, 2021 Researchers in Israel have developed a sensitive, rapid, antibody-independent assay for the identification of ricin in body fluids using mass spectrometry. The assay involves lectin affinity capturing of ricin by easy-to-use commercial lactose–agarose beads, followed by tryptic digestion and selected marker identification using targeted Multiple Reaction Monitoring analysis. This enables ricin identification down to 5 ng/mL in serum samples in 2.5 hours. They demonstrated the technology in a clinical scenario where the toxin was identified in an abdominal fluid sample taken 72 h post self-injection of castor beans extraction. This method has the potential application […]
Record-breaking laser link could help us test whether Einstein was right
Science Daily January 22, 2021 An international team of researchers (Australia, France) combined phase stabilisation technology with advanced self-guiding optical terminals that allowed laser signals to be sent from one point to another without interference from the atmosphere. They demonstrated phase-stabilized optical frequency transfer over a 265 m horizontal point-to-point free-space link between optical terminals with active tip-tilt mirrors to suppress beam wander, in a compact, human-portable set-up. They could correct for atmospheric turbulence in 3D, that is, left-right, up-down and, critically, along the line of flight. According to the researchers if you have one of these optical terminals on the […]
Researchers achieve extreme-ultraviolet spectral compression by four-wave mixing
Phys.org January 25, 2021 Nonlinear optical techniques have made it possible to change the color of light and modify its spectral bandwidth without compromising the intensity. However, nonlinear optical techniques are not readily available in the XUV region of the electromagnetic spectrum. Researchers in Germany have demonstrated a concept for efficient spectral compression by four-wave mixing exploiting a phase-matching scheme based on closely spaced resonances. They compressed broadband radiation in the 145–130 nm wavelength range into a narrow-bandwidth XUV pulse at 100.3 nm wavelength in the presence of a broadband near-infrared pulse in a krypton gas jet. The narrowband XUV pulses has […]
Researchers construct molecular nanofibers that are stronger than steel
MIT News January 25, 2021 Small-molecule self-assembly is an established route for producing high-surface-area nanostructures with readily customizable chemistries and precise molecular organization. The whole structure falls apart when you remove water, particularly when any kind of external force is applied. An international team of researchers (USA – MIT, Argonne National Laboratory, France) has shown that a small-molecule platform, the aramid amphiphile overcomes these dynamic instabilities by incorporating a Kevlar-inspired domain into the molecular structure. Strong, anisotropic interactions between aramid amphiphiles suppress molecular exchange and elicit spontaneous self-assembly in water to form nanoribbons with lengths of up to 20 micrometres. […]