Phys.org February 8, 2024 Lens design is of paramount importance in the evolving world of technology, where compactness and high optical performance are a necessity. Freeform design techniques allow us to transcend traditional limitations, but creating new optics remains a substantial challenge unless we consider unconventional physical phenomenon. Researchers in France introduced a lens type based on freeform design, employing spiralization of one of its diopters that resulted in optical vortices. This enabled multifocality, primarily serving needs in ophthalmology; however, its potential applications could broadly impact many other domains. According to the researchers their lens design could be crucial in […]
Tag Archives: S&T France
Study offers a broader approach to quantum walks
Phys.org July 14, 2023 Quantum walks have been widely studied for their ability to simulate a wide range of transport phenomena. Physicists have previously studied two distinct types of quantum walk, but so far, they haven’t widely considered how their mathematical descriptions could be linked. They have long been considered the discrete-time and discrete space analogue of the Dirac equation and have been used as a primitive to simulate quantum field theories precisely because of some of their internal symmetries. Researchers in France have introduced a new family of quantum walks, a more general family named “twisted” quantum walkers, named […]
Using lasers to bond semiconductor electronics components
Phys.org December 5, 2022 Important physical limitations have prevented applying laser micro-welding to silicon (Si) and other technology-essential semiconductors. High intensities are required for internal glass modification. However, they result in strong propagation nonlinearities which defocus and delocalize intense infrared radiation. To overcome this, researchers in France created defects inside silicon that later serve as weak points to produce clean-edge cuts. The defects acted as strong bonding points. After setting up the right conditions to circumvent the effects, they successfully made the first experimental demonstration of silicon-silicon laser welding. After an optimization process, they extended the technique to gallium arsenide […]
Months of gravity changes preceded the Tōhoku earthquake
Phys.org September 1, 2022 Researchers in France conducted a global analysis of Gravity Recovery and Climate Experiment (GRACE) reconstructed gravity gradients from July 2004 to February 2011 to test whether the deep signals preceding the March 2011 Tohoku earthquake could be detected before the event as a specific feature originating from solid Earth. They improved the angular resolution of the gravity gradients using two overlapping ranges of azimuthal sensitivity to investigate short-term signals of large amplitude aligned with the orientation of the Northwestern Pacific subduction and set-up a method to identify consistent solid Earth signals shared by different GRACE gravity […]
Why thinking hard makes you tired
Science Daily August 11, 2022 Beyond subjective report, cognitive fatigue has been conceived as an inflated cost of cognitive control, objectified by more impulsive decisions. Researchers in France have proposed a neuro-metabolic account: the cost would relate to the necessity of recycling potentially toxic substances accumulated during cognitive control exertion. They validated this account using magnetic resonance spectroscopy (MRS) to monitor brain metabolites throughout an approximate workday, during which two groups of participants performed either high-demand or low-demand cognitive control tasks, interleaved with economic decisions. Choice-related fatigue markers were only present in the high-demand group, with a reduction of pupil […]
Balloon fleet senses earthquakes from stratosphere
Phys.org July 28, 2022 Note: This article has been accepted for publication and undergone full peer review but has not been through the copyediting… The ground movements induced by seismic waves create acoustic waves propagating upward in the atmosphere, providing a practical solution to perform remote sensing of planetary interiors. However, a terrestrial demonstration of a seismic network based on balloon-carried pressure sensors has not been provided. Researchers in France reported the detection of a large, distant earthquake in a network of balloon-bound pressure sensors in the stratosphere. They demonstrated that quakes properties and planet internal structure can be probed […]
Tonga Islands: A seismic algorithm reveals the magnitude of the January 2022 eruption
Phys.org April 20, 2022 By analyzing the seismic waves researchers in France were able to design an algorithm that can detect and locate a volcanic eruption in near real-time and, using equations that describe explosive eruptions, assess its size. Until now, such an assessment required field work and took several weeks or months, since it was necessary to estimate the volume of ash and lava produced. The authors show that the Hunga Tonga eruption ejected a volume of around 10 km3, making it the largest explosive eruption of the twenty-first century, equivalent in strength to that of the devastating eruption […]
Iodine successfully tested in satellite ion thrusters
Phys.org November 18, 2021 Xenon is used almost exclusively as an ionizable propellant for space propulsion. However, xenon is rare, it must be stored under high pressure and production cost is high. Researchers in France used iodine propellant in a system and presented in-orbit results of the technology. They stored iodine as a solid and sublimated at low temperatures. Plasma was produced with a radio-frequency inductive antenna with enhanced ionization efficiency. Both atomic and molecular iodine ions were accelerated by high-voltage grids to generate thrust, and a highly collimated beam was produced with substantial iodine dissociation. The propulsion system was […]
Keeping one step ahead of earthquakes
Phys.org November 3, 2021 According to the researchers in France AI has the potential to improve the accuracy and speed of early warning systems. Earthquake early warning (EEW) systems are evolving rapidly due to advances in computer power and network communication. They work by identifying the first signals generated by an earthquake rupture before the strongest shaking and tsunami reach populated areas. These signals follow the origin of the earthquake and can be recorded seconds before the seismic waves. Prompt elasto-gravity signal (PEGS) which was recently identified travels at the speed of light but is a million times smaller than […]
An artificial ionic neuron for tomorrow’s electronic memories
Nanowerk August 17, 2021 Researchers in France report that devices made of a single layer of water transporting ions within graphene nanoslits have the same transmission capacity as a neuron. They developed an analytical theory, backed up by molecular dynamics simulations, that predicts strongly nonlinear effects in ion transport across quasi–two-dimensional slits. They showed that under an electric field, ions assemble into elongated clusters, whose slow dynamics result in hysteretic conduction. The memristor effect, can be harnessed to build an elementary neuron. As a proof of concept, they carried out molecular simulations of two nanofluidic slits that reproduced the Hodgkin-Huxley […]