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Topic Review
Planetary Radar
Planetary radar observations have provided invaluable information on the solar system through both ground-based and space-based observations. The radar technology is a remote-sensing method for planetary exploration and the methods to interpret the radar data have advanced in the eight decades of increasing use, where the field stands in the early 2020s, and what are the future prospects of the ground-based facilities conducting planetary radar observations and the planned spacecraft missions equipped with radar instruments. 
  • 418
  • 11 Dec 2023
Biography
Alan Tower Waterman
Alan Tower Waterman (June 4, 1892 – November 30, 1967) was an United States physicist. Born in Cornwall-on-Hudson, New York, he grew up in Northampton, Massachusetts. His father was a professor of physics at Smith College. Alan also became a physicist, doing his undergraduate and doctoral work at Princeton University, from which he obtained his Ph.D. in 1916.[1] He joined the faculty of the
  • 416
  • 26 Dec 2022
Biography
Bruno Augenstein
Bruno Wilhelm Augenstein (March 16, 1923 – July 6, 2005) was a Germany -born mathematician and physicist who made important contributions in space technology, ballistic missile research, satellites, antimatter, and many other areas. Augenstein worked in the Aerophysics Laboratory at North American Aviation on diverse projects including weaponization of the V-2 rocket, a ramjet-powered vehic
  • 415
  • 09 Dec 2022
Topic Review
Kikuchi Line
Kikuchi lines pair up to form bands in electron diffraction from single crystal specimens, there to serve as "roads in orientation-space" for microscopists not certain what they are looking at. In transmission electron microscopes, they are easily seen in diffraction from regions of the specimen thick enough for multiple scattering. Unlike diffraction spots, which blink on and off as one tilts the crystal, Kikuchi bands mark orientation space with well-defined intersections (called zones or poles) as well as paths connecting one intersection to the next. Experimental and theoretical maps of Kikuchi band geometry, as well as their direct-space analogs e.g. bend contours, electron channeling patterns, and fringe visibility maps are increasingly useful tools in electron microscopy of crystalline and nanocrystalline materials. Because each Kikuchi line is associated with Bragg diffraction from one side of a single set of lattice planes, these lines can be labeled with the same Miller or reciprocal-lattice indices that are used to identify individual diffraction spots. Kikuchi band intersections, or zones, on the other hand are indexed with direct-lattice indices i.e. indices which represent integer multiples of the lattice basis vectors a, b and c. Kikuchi lines are formed in diffraction patterns by diffusely scattered electrons, e.g. as a result of thermal atom vibrations. The main features of their geometry can be deduced from a simple elastic mechanism proposed in 1928 by Seishi Kikuchi, although the dynamical theory of diffuse inelastic scattering is needed to understand them quantitatively. In x-ray scattering these lines are referred to as Kossel lines (named after Walther Kossel).
  • 415
  • 18 Nov 2022
Topic Review
Classical Approaches at the Synchrotron Radiation Facilites
Synchrotron radiation sources are widely used in interdisciplinary research, generating an enormous amount of data while posing serious challenges to the storage, processing, and analysis capabilities of the large-scale scientific facilities worldwide.
  • 414
  • 15 May 2023
Topic Review
Coronal Cloud
A coronal cloud is the cloud of hot plasma gas surrounding a coronal mass ejection. It is usually made up of protons and electrons. When a coronal mass ejection occurs at the Earth's Sun, it is the coronal cloud that usually reaches Earth and causes damage to electrical equipment and space satellites, not the ejection or flare itself. The damage is mostly the result of the high amount of electricity moving through the atmosphere. A coronal cloud is released when a solar flare becomes a coronal mass ejection; the coronal cloud often contains more radioactive particles than the mass ejection itself. A coronal mass ejection occurs when a solar flare becomes so hot that it snaps and breaks in two, becoming a "rope" of heat and magnetism that stretches between two sunspots. The resulting coronal mass ejection can be compared to a horseshoe magnet, the sunspots being the poles and the oscillating magnetic connector the handle. Coronal mass ejections typically do not last very long, because they cool down as the coronal cloud of gas is released and begins to hurtle away from the Sun.
  • 414
  • 07 Oct 2022
Topic Review
Sensor Applications of Forward Brillouin Scattering
In-fiber opto-mechanics based on forward Brillouin scattering enables sensing the surrounding of the optical fiber. Optical fiber transverse acoustic resonances are sensitive to both the inner properties of the optical fiber and the external medium. A particularly efficient pump and probe technique—assisted by a fiber grating—can be exploited for the development of point sensors of only a few centimeters in length. When measuring the acoustic resonances, this technique provides the narrowest reported linewidths and a signal-to-noise ratio better than 40 dB. The longitudinal and transverse acoustic velocities—normalized with the fiber radius—can be determined with a relative error lower than 10−4, exploiting the derivation of accurate asymptotic expressions for the resonant frequencies. 
  • 413
  • 17 Feb 2023
Topic Review
Blue Light and Eye Damage
Personal digital devices, emitting high-energy light, namely in the blue wavelength, have raised concerns about possible harmful effects on users’ eyes. Scientific research history has shown a relationship between exposure to blue light and changes in ocular structures.
  • 413
  • 18 May 2023
Topic Review
Deep Learning for Photonic Inverse Design
Inspired by the fast development of deep learning, people have combined the DL techniques with inverse design. At present, DL has been developed rapidly in the field of photonic device inverse design, which can be more efficient than traditional iterative optimization methods.
  • 413
  • 26 Jul 2023
Topic Review
Two-Dimensional Materials in Nonlinear Optical Devices
All-optical signal processing based on nonlinear optical devices is promising for ultrafast information processing in optical communication systems. Recent advances in two-dimensional (2D) layered materials with unique structures and distinctive properties have opened up new avenues for nonlinear optics and the fabrication of related devices with high performance. 
  • 412
  • 13 Feb 2023
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