Topic Review
Lower Limb Joint Kinematics
The use of inertial measurement units (IMUs) has gained popularity for the estimation of lower limb kinematics. However, implementations in clinical practice are still lacking. This review shows that methods for lower limb joint kinematics are inherently application dependent. Sensor restrictions are generally compensated with biomechanically inspired assumptions and prior information. Awareness of the possible adaptations in the IMU-based kinematic estimates by incorporating such prior information and assumptions is necessary, before drawing clinical decisions. Future research should focus on alternative validation methods, subject-specific IMU-based biomechanical joint models and disturbed movement patterns in real-world settings.
  • 979
  • 01 Nov 2020
Topic Review
Lower-Energy Irradiation Effects on MgO-Based Magnetic Tunnel Junctions
Electromagnetic waves with wavelengths longer than gamma rays are commonly known as lower-energy waves, such as X-rays, ultraviolet radiation (UV), visible light, infrared radiation, microwaves, and radio waves. These electromagnetic waves have less energy compared to gamma rays, and are generally classified as non-ionizing radiation, with the exception of X-rays.  This discussion revolves the impacts of lower-energy electromagnetic waves on magnetic tunnel junctions (MTJs) that comprise two ferromagnetic layers separated by a thin insulating barrier.
  • 287
  • 01 Jun 2023
Topic Review
LSPR Gas Sensors
The localized surface plasmon resonance (LSPR) phenomenon is known to be responsible for the unique colour effects observed in the ancient Roman Lycurgus Cup and at the windows of the medieval cathedrals. In both cases, the optical effects result from the interaction of the visible light (scattering and absorption) with the conduction band electrons of noble metal nanoparticles (gold, silver, and gold–silver alloys). These nanoparticles are dispersed in a dielectric matrix with a relatively high refractive index in order to push the resonance to the visible spectral range. At the same time, they have to be located at the surface to make LSPR sensitive to changes in the local dielectric environment, the property that is very attractive for sensing applications.
  • 1.3K
  • 29 Jun 2021
Topic Review
Luch (Satellite)
The Luch (Russian: Луч; lit. Ray) Satellite Data Relay Network (SDRN), also referred to as Altair and Gelios, is a series of geosynchronous Russian relay satellites, used to transmit live TV images, communications and other telemetry from the Soviet/Russian space station Mir, the Russian Orbital Segment (ROS) of the International Space Station and other orbital spacecraft to the Earth, in a manner similar to that of the US Tracking and Data Relay Satellite System.
  • 613
  • 21 Nov 2022
Topic Review
Luminescent Carbon Nanoparticles
Among the newest nanostructured luminescent materials, carbon nanoparticles, commonly known as carbon nanodots (CNDs), are of special interest. The term CNDs is commonly used to refer to carbonaceous particles with a size of less than 10 nm. However, the structure and morphology of these particles can be quite diverse. They can include nanoparticles of diamond and graphite, as well as amorphous nanoparticles with a diamond-like, polymer-like, or graphite-like structure. Nanoflakes of graphene and graphene oxide are also often referred to as CNDs. This manuscript referes to luminescent carbon nanoprecipitates synthesised by pyrolysis/thermolysis of organic precursors and  despersed in nanoporous silicas.
  • 568
  • 20 Dec 2021
Topic Review
Luminiferous Aether
Luminiferous aether or ether ("luminiferous", meaning "light-bearing") was the postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space, something that waves should not be able to do. The assumption of a spatial plenum of luminiferous aether, rather than a spatial vacuum, provided the theoretical medium that was required by wave theories of light. The aether hypothesis was the topic of considerable debate throughout its history, as it required the existence of an invisible and infinite material with no interaction with physical objects. As the nature of light was explored, especially in the 19th century, the physical qualities required of an aether became increasingly contradictory. By the late 1800s, the existence of the aether was being questioned, although there was no physical theory to replace it. The negative outcome of the Michelson–Morley experiment (1887) suggested that the aether did not exist, a finding that was confirmed in subsequent experiments through the 1920s. This led to considerable theoretical work to explain the propagation of light without an aether. A major breakthrough was the theory of relativity, which could explain why the experiment failed to see aether, but was more broadly interpreted to suggest that it was not needed. The Michelson-Morley experiment, along with the blackbody radiator and photoelectric effect, was a key experiment in the development of modern physics, which includes both relativity and quantum theory, the latter of which explains the particle-like nature of light.
  • 3.4K
  • 17 Oct 2022
Topic Review
Lunar Outpost (NASA)
A lunar outpost is a concept of a permanent or semi-permanent presence of humans on the Moon, a moonbase, by the United States space administration NASA. NASA requested an increase in the 2020 budget of $1.6 billion, in order to make another crewed mission to the Moon by 2025 (originally 2024), followed by a sustained presence on the Moon by 2028.
  • 1.4K
  • 23 Nov 2022
Topic Review
Lunar Regolith Penetrating Radar
An extraordinary component of this mission is the “Lunar Regolith Penetrating Radar” (LRPR) housed within its lander, which currently stands as the most advanced payload in terms of vertical resolution among all penetrating radars employed in lunar exploration.
  • 257
  • 10 Nov 2023
Topic Review
Lupus
Lupus, the Latin word for "wolf," is a constellation located in the southern celestial hemisphere. Representing a wolf, it was one of the 48 constellations listed by Ptolemy, and is one of the 88 modern constellations recognized by the International Astronomical Union.
  • 233
  • 15 Mar 2024
Topic Review
Lynx
Lynx is a faint constellation located in the northern celestial hemisphere, bordered by Ursa Major, Auriga, Gemini, and Cancer. Named after the wild cat known for its keen vision, Lynx is notable for its lack of bright stars but contains several galaxies and deep-sky objects, making it of interest to astronomers.
  • 233
  • 15 Mar 2024
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