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Topic Review
Kounotori Integrated Tether Experiment
Kounotori 6 (こうのとり6号機), also known as HTV-6, is the sixth flight of the H-II Transfer Vehicle, an uncrewed cargo spacecraft launched to resupply the International Space Station. It was launched at 13:26:47 UTC on 9 December 2016 aboard H-IIB launch vehicle from Tanegashima Space Center.
  • 2.2K
  • 27 Oct 2022
Topic Review
Study of Animal Locomotion
The study of animal locomotion is a branch of biology that investigates and quantifies how animals move.
  • 2.2K
  • 24 Oct 2022
Topic Review
Biaxial Tensile Testing
Biaxial tensile testing is a versatile technique to address the mechanical characterization of planar materials. Typical materials tested in biaxial configuration include metal sheets, silicone elastomers, composites, thin films, textiles and biological soft tissues.
  • 2.2K
  • 24 Oct 2022
Topic Review
Stationary Action Principle
The stationary action principle – also known as the principle of least action – is a variational principle that, when applied to the action of a mechanical system, yields the equations of motion for that system. The principle states that the trajectories (i.e. the solutions of the equations of motion) are stationary points (a.k.a. critical points) of the system's action functional. The term "least action" is a historical misnomer since the principle has no minimality requirement: the value of the action functional need not be minimal (even locally) on the trajectories. The principle can be used to derive Newtonian, Lagrangian and Hamiltonian equations of motion, and even general relativity (see Einstein–Hilbert action). In relativity, a different action must be minimized or maximized. The classical mechanics and electromagnetic expressions are a consequence of quantum mechanics. The stationary action method helped in the development of quantum mechanics. In 1933, the physicist Paul Dirac demonstrated how this principle can be used in quantum calculations by discerning the quantum mechanical underpinning of the principle in the quantum interference of amplitudes. Subsequently Julian Schwinger and Richard Feynman independently applied this principle in quantum electrodynamics. The principle remains central in modern physics and mathematics, being applied in thermodynamics, fluid mechanics, the theory of relativity, quantum mechanics, particle physics, and string theory and is a focus of modern mathematical investigation in Morse theory. Maupertuis' principle and Hamilton's principle exemplify the principle of stationary action. The action principle is preceded by earlier ideas in optics. In Ancient Greece , Euclid wrote in his Catoptrica that, for the path of light reflecting from a mirror, the angle of incidence equals the angle of reflection. Hero of Alexandria later showed that this path was the shortest length and least time. Scholars often credit Pierre Louis Maupertuis for formulating the principle of least action because he wrote about it in 1744 and 1746. However, Leonhard Euler discussed the principle in 1744, and evidence shows that Gottfried Leibniz preceded both by 39 years.
  • 2.1K
  • 14 Oct 2022
Topic Review
Masten Space Systems
Masten Space Systems was an aerospace manufacturer startup company in Mojave, California (formerly in Santa Clara, California) that is developing a line of vertical takeoff, vertical landing (VTVL) rockets, initially for uncrewed research sub-orbital spaceflights and eventually intended to support robotic orbital spaceflight launches. In 2020, NASA awarded Masten a contract for a lunar lander mission; NASA is to pay Masten US$75.9 million for Masten to build and launch a lander called XL-1 to take NASA and other customer payloads to the south pole of the Moon. Masten Mission One will be Masten's first space flight; it is scheduled for launch in November 2023. The company filed for Chapter 11 bankruptcy on 28 July 2022. The company would later be purchased by Astrobotic Technology on 11 September 2022.
  • 2.1K
  • 26 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.
  • 2.1K
  • 17 Oct 2022
Topic Review
Electrostatic Dust Cloth
Electrostatic dust cloths (EDC) have been widely used for microbiologic contamination assessment in different indoor and occupational environments. Electrostatic dust cloths are negatively charged allowing dust particles to settle with greater ease.
  • 2.1K
  • 31 Mar 2022
Biography
Evan O'Neill Kane
Evan O'Neill Kane (December 23, 1924 – March 23, 2006), known as E. O. Kane in his publications, was an American physicist who established some of the basic understanding of the theory of semiconductors that are now used in consumer and other electronics. He was one of the main developers of the k·p perturbation theory which is used to calculate band structures. Kane's great, great uncle,
  • 2.1K
  • 09 Dec 2022
Topic Review
Solar Physics
Solar physics is the branch of astrophysics that specializes in the study of the Sun. It deals with detailed measurements that are possible only for our closest star. It intersects with many disciplines of pure physics, astrophysics, and computer science, including fluid dynamics, plasma physics including magnetohydrodynamics, seismology, particle physics, atomic physics, nuclear physics, stellar evolution, space physics, spectroscopy, radiative transfer, applied optics, signal processing, computer vision, computational physics, stellar physics and solar astronomy. Because the Sun is uniquely situated for close-range observing (other stars cannot be resolved with anything like the spatial or temporal resolution that the Sun can), there is a split between the related discipline of observational astrophysics (of distant stars) and observational solar physics. The study of solar physics is also important as it provides a "physical laboratory" for the study of plasma physics.
  • 2.1K
  • 29 Sep 2022
Topic Review
Entrance Length
In fluid dynamics, the entrance length is the distance a flow travels after entering a pipe before the flow becomes fully developed. Entrance length refers to the length of the entry region, the area following the pipe entrance where effects originating from the interior wall of the pipe propagate into the flow as an expanding boundary layer. When the boundary layer expands to fill the entire pipe, the developing flow becomes a fully developed flow, where flow characteristics no longer change with increased distance along the pipe. Many different entrance lengths exist to describe a variety of flow conditions. Hydrodynamic entrance length describes the formation of a velocity profile caused by viscous forces propagating from the pipe wall. Thermal entrance length describes the formation of a temperature profile. Awareness of entrance length may be necessary for the effective placement of instrumentation, such as fluid flow meters.
  • 2.1K
  • 17 Oct 2022
Topic Review
Quantum Biology
Recent evidence suggests that a broad range of complex and dynamic processes in living systems could exploit quantum effects to enhance and/or regulate biological functions. These non-trivial quantum effects may play a crucial role in maintaining the non-equilibrium state of biomolecular systems so as to achieve biological advantages that cannot be understood within the boundaries of classical physics. Quantum biology is the study of such quantum aspects of living systems. 
  • 2.1K
  • 24 Mar 2021
Biography
Rudolf Haag
Rudolf Haag (17 August 1922 – 5 January 2016) was a German theoretical physicist, who mainly dealt with fundamental questions of quantum field theory. He was one of the founders of the modern formulation of quantum field theory and he identified the formal structure in terms of the principle of locality and local observables. He also made important advances in the foundations of quantum statis
  • 2.0K
  • 30 Nov 2022
Biography
Nima Arkani-Hamed
Nima Arkani-Hamed (Persian: نیما ارکانی حامد‎; born April 5, 1972) is an Iranian-American-Canadian[1][2] theoretical physicist, with interests in high-energy physics, quantum field theory, string theory, cosmology and collider physics. Arkani-Hamed is a member of the permanent faculty at the Institute for Advanced Study in Princeton, New Jersey.[3] He is also director of The Cent
  • 2.0K
  • 01 Dec 2022
Topic Review
Elementary Charge and Vacuum Energy
Classical electrodynamics was introduced by James Clear Maxwell nearly 150 years ago and it is a subject that had been thoroughly explored over these years. Notwithstanding this long term scrutiny of this subject, there are hidden features in classical electrodynamics that actually heralds the emergence of Quantum electrodynamics in the future. Such examples can be found when analyzing the electromagnetic radiation generated by antennas working in both frequency and time domain and in the case of transition radiation generated by decelerating electrons. Here we discuss one such case. Consider the radiation generated by an antenna working in frequency domain. One can show that the energy dissipated as radiation within half a period of oscillation, say U, satisfies the inequality U ≥ hf →q ≥ e where q  is the magnitude of the oscillating charge in the antenna, e is the elementary charge, f is the frequency of oscillation and h is the Planck constant. This result is derived while adhering strictly to the principles of classical electrodynamics alone. Combining this result with the concept of photons burrowed from quantum mechanics, one can derive an expression for the elementary charge as a function of other natural constants and the energy density of vacuum. The expression predicts the value of elementary charge to an accuracy higher than about 0.1%.
  • 2.0K
  • 01 Nov 2020
Topic Review
Gravitation
In physics, gravitation or gravity is the tendency of objects with mass to accelerate toward each other. Gravitation is one of the four fundamental interactions in nature, the other three being the electromagnetic force, the weak nuclear force, and the strong nuclear force. Gravitation is the weakest of these interactions, but acts over great distances and is always attractive. In classical mechanics, gravitation arises out of the force of gravity (which is often used as a synonym for gravitation). In general relativity, gravitation arises out of spacetime being curved by the presence of mass, and is not a force. In quantum gravity theories, either the graviton is the postulated carrier of the gravitational force, or time-space itself is envisioned as discrete in nature, or both. Classically, the gravitational attraction of the earth endows objects with weight and causes them to fall to the ground when dropped (the earth also moves toward the object, but only by an infinitesimal amount). Moreover, gravitation is the reason for the very existence of the earth, the sun, and other celestial bodies; without it matter would not have coalesced into these bodies and life as we know it would not exist. Gravitation is also responsible for keeping the earth and the other planets in their orbits around the sun, the moon in its orbit around the earth, for the formation of tides, and for various other natural phenomena that we observe.
  • 2.0K
  • 14 Oct 2022
Topic Review
SPOT (Satellite)
SPOT (French: Satellite Pour l’Observation de la Terre, lit. "Satellite for observation of Earth") is a commercial high-resolution optical imaging Earth observation satellite system operating from space. It is run by Spot Image, based in Toulouse, France . It was initiated by the CNES (Centre national d'études spatiales – the French space agency) in the 1970s and was developed in association with the SSTC (Belgian scientific, technical and cultural services) and the Swedish National Space Board (SNSB). It has been designed to improve the knowledge and management of the Earth by exploring the Earth's resources, detecting and forecasting phenomena involving climatology and oceanography, and monitoring human activities and natural phenomena. The SPOT system includes a series of satellites and ground control resources for satellite control and programming, image production, and distribution. Earlier satellites were launched using the European Space Agency's Ariane 2, 3, and 4 rockets, while SPOT 6 and SPOT 7 were launched by the Indian PSLV.
  • 2.0K
  • 24 Nov 2022
Biography
Paul Steinhardt
Paul Joseph Steinhardt (born December 25, 1952) is an American theoretical physicist whose principal research is in cosmology and condensed matter physics. He is currently the Albert Einstein Professor in Science at Princeton University where he is on the faculty of both the Departments of Physics and of Astrophysical Sciences. [1] Steinhardt is best known for his development of new theories of
  • 2.0K
  • 30 Nov 2022
Topic Review
Temperature Sensitive Optical Parameters
In the new age of illumination, light emitting diodes (LEDs) have been proven to be the most efficient alternative to conventional light sources. Yet, in comparison to other lighting systems, LEDs operate at low temperatures while junction temperature (Tj) is among the main factors dictating their lifespan, reliability, and performance. Tj may be indirectly measured using an LED’s inherent optical characteristics. The emission spectrum of a semiconductor device is influenced by temperature variations due to the temperature dependence of the energy band gap. This behavior motivates researchers to use spectral power distribution (SPD) characteristics such as the peak wavelength and spectral bandwidth of LEDs, which are known as temperature sensitive optical parameters (TSOPs), to estimate Tj. 
  • 2.0K
  • 25 Oct 2022
Topic Review
Thermodynamics of the Universe
The thermodynamics of the universe is dictated by which form of energy dominates it - relativistic particles which are referred to as radiation, or non-relativistic particles which are referred to as matter. The former are particles whose rest mass is zero or negligible compared to their energy, and therefore move at the speed of light or very close to it; the latter are particles whose kinetic energy is much lower than their rest mass and therefore move much slower than the speed of light. The intermediate case is not treated well analytically.
  • 2.0K
  • 09 Nov 2022
Biography
Franz Josef Giessibl
Franz Josef Gießibl (born 27 May 1962 in Amerang) is a Germany physicist and university professor at the University of Regensburg. Giessibl studied physics from 1982 to 1987 at the Technical University of Munich and at Eidgenössische Technischen Hochschule Zürich. He received a diploma in experimental physics in 1988 with Professor Gerhard Abstreiter and continued with a PhD in physics wit
  • 1.9K
  • 12 Dec 2022
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