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Topic Review
Ultrafast Fiber Technologies for Compact Laser Wake Field
Technologies, performances and maturity of ultrafast fiber lasers and fiber delivery of ultrafast pulses are used for the medical deployment of laser-wake-field acceleration (LWFA). The compact ultrafast fiber lasers produce intense laser pulses with flexible hollow-core fiber delivery to facilitate electron acceleration in the laser-stimulated wake field near treatment site, empowering endoscopic LWFA brachytherapy. With coherent beam combination of multiple fiber amplifiers, the advantages of ultrafast fiber lasers are further extended to bring in more capabilities in compact LWFA applications.
  • 514
  • 08 Jul 2022
Topic Review
Udwadia–Kalaba Equation
In theoretical physics, the Udwadia–Kalaba equation is a method for deriving the equations of motion of a constrained mechanical system. The equation was first described by Firdaus E. Udwadia and Robert E. Kalaba in 1992. The approach is based on Gauss's principle of least constraint. The Udwadia–Kalaba equation applies to both holonomic constraints and nonholonomic constraints, as long as they are linear with respect to the accelerations. The equation generalizes to constraint forces that do not obey D'Alembert's principle.
  • 489
  • 14 Oct 2022
Topic Review
U-NII
The Unlicensed National Information Infrastructure (U-NII) radio band is part of the radio frequency spectrum used by IEEE 802.11a devices and by many wireless ISPs. It operates over four ranges: Wireless ISPs generally use 5.725–5.825 GHz. In the USA licensed amateur radio operators are authorized 5.650–5.925 GHz by Part 97.303 of the FCC rules. U-NII is an FCC regulatory domain for 5 GHz wireless devices. U-NII power limits are defined by the United States CFR Title 47 (Telecommunication), Part 15 - Radio Frequency Devices, Subpart E - Unlicensed National Information Infrastructure Devices, Paragraph 15.407 - General technical requirements. Regulatory use in individual countries may differ. The European HiperLAN standard operates in same frequency band as the U-NII.
  • 837
  • 17 Oct 2022
Topic Review
Types of Snow
Types of snow can be designated by the shape of its flakes, description of how it is falling, and by how it collects on the ground. A blizzard and snow storm indicate heavy snowfalls over a large area, snow squalls give heavy snowfalls over narrow bands, while flurries are used for the lightest snowfall. Types which fall in the form of a ball, rather than a flake, are known as graupel, with sleet and snow grains as types of graupel. Once on the ground, snow can be categorized as powdery when fluffy, granular when it begins the cycle of melting and refreezing, and crud or eventually ice once it packs down into a dense drift after multiple melting and refreezing cycles. When powdering, snow drifts with the wind or ground blizzard, sometimes to the depth of several metres. After attaching to hillsides, blown snow can evolve into a snow slab, which is an avalanche hazard on steep slopes.
  • 2.8K
  • 04 Nov 2022
Topic Review
Types of Membrane Transporters in Plants
Membrane transporters are proteins that mediate the entry and exit of substances through the plasma membrane and organellar membranes and are capable of recognizing and binding to specific substances, thereby facilitating substance transport. Membrane transporters are divided into different types, e.g., ion transporters, sugar transporters, amino acid transporters, and aquaporins, based on the substances they transport. These membrane transporters inhibit reactive oxygen species (ROS) generation through ion regulation, sugar and amino acid transport, hormone induction, and other mechanisms. They can also promote enzymatic and nonenzymatic reactions in plants, activate antioxidant enzyme activity, and promote ROS scavenging. Moreover, membrane transporters can transport plant growth regulators, solute proteins, redox potential regulators, and other substances involved in ROS metabolism through corresponding metabolic pathways, ultimately achieving ROS homeostasis in plants.
  • 140
  • 20 Feb 2024
Topic Review
Types of Liquid Crystals
The liquid-crystalline state of matter (mesomorphic state, or mesophase) is intermediate between the crystalline and liquid states, simultaneously showing some of the anisotropic properties of solids and the fluidity of liquids. In this state, materials demonstrate a tendency to flow like liquids and have some properties similar to solids. LCs may be divided into two main classes, named thermotropics and lyotropics. The importance of liquid crystals, alongside with their technical applications, lies in their role as carriers of life. In fact, fully ordered solids are a dead matter, and fully disordered liquids are also dead. But liquid crystals, as partially ordered soft matter systems, bear all qualities that had been necessary for the emergence of life. Practically all biological structures show some features pf liquid crystalline ordering. 
  • 624
  • 15 Jun 2023
Topic Review
Types of Liquid Crystal Biosensors
Interactions between liquid crystal molecules and target analytes open up various biosensing applications for quick screening and point-of-care applications. There exist different kinds of biosensors, such as electrochemical, wearable, amperometric, potentiometric, optical, impedimetric and thermometric. Liquid crystal (LC) biosensors belong to the type of optical biosensors, which employ its anisotropy and sensitivity to external stimuli. As it is known, LCs are highly sensitive to environment changes, e.g., temperature, electric fields and surface interactions. The inherent property of LCs to respond to external stimuli gives LC biosensors a high potential to contribute to the new biosensing era. 
  • 417
  • 02 Jan 2024
Topic Review
Types of Compton Cameras
A Compton camera is a promising γ-ray detector that operates in the wide energy range of a few tens of keV to MeV. The γ-ray detection method of a Compton camera is based on Compton scattering kinematics, which is used to determine the direction and energy of the γ-rays without using a mechanical collimator. Although the Compton camera was originally designed for astrophysical applications, it was later applied in medical imaging as well. Moreover, its application in environmental radiation measurements is also under study.
  • 450
  • 18 Oct 2022
Topic Review
Two-Ray Ground-Reflection Model
The Two-Rays Ground Reflected Model is a radio propagation model which predicts the path losses between a transmitting antenna and a receiving antenna when they are in LOS (line of sight). Generally, the two antenna each have different height. The received signal having two components, the LOS component and the multipath component formed predominantly by a single ground reflected wave.
  • 6.9K
  • 08 Nov 2022
Topic Review
Two-Dimensional Quantum Billiards
Two-dimensional quantum billiards are one of the most important paradigms for exploring the connection between quantum and classical worlds. Researchers are mainly focused on nonintegrable and irregular shapes to understand the quantum characteristics of chaotic billiards. The emergence of the scarred modes relevant to unstable periodic orbits (POs) is one intriguing finding in nonintegrable quantum billiards. On the other hand, stable POs are abundant in integrable billiards. The quantum wavefunctions associated with stable POs have been shown to play a key role in ballistic transport. 
  • 367
  • 19 Oct 2023
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