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Topic Review
Infrastructure
Infrastructure is the set of fundamental facilities and systems serving a country, city, or other area, including the services and facilities necessary for its economy to function. Infrastructure is composed of public and private physical structures such as roads, railways, bridges, tunnels, water supply, sewers, electrical grids, and telecommunications (including Internet connectivity and broadband speeds). In general, it has also been defined as "the physical components of interrelated systems providing commodities and services essential to enable, sustain, or enhance societal living conditions". There are two general types of ways to view infrastructure: hard and soft. Hard infrastructure refers to the physical networks necessary for the functioning of a modern industry. This includes roads, bridges, railways, etc. Soft infrastructure refers to all the institutions that maintain the economic, health, social, and cultural standards of a country. This includes educational programs, official statistics, parks and recreational facilities, law enforcement agencies, and emergency services. The word infrastructure has been used in French since 1875 and in English since 1887, originally meaning "The installations that form the basis for any operation or system". The word was imported from French, where it was already used for establishing a roadbed of substrate material, required before railroad tracks or constructed pavement could be laid on top of it. The word is a combination of the Latin prefix "infra", meaning "below", as many of these constructions are underground (for example, tunnels, water and gas systems, and railways), and the French word "structure" (derived from the Latin word "structure"). The army use of the term achieved currency in the United States after the formation of NATO in the 1940s, and by 1970 was adopted by urban planners in its modern civilian sense.
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Topic Review
Osmium-167
Osmium (76Os) has seven naturally occurring isotopes, five of which are stable: 187Os, 188Os, 189Os, 190Os, and (most abundant) 192Os. The other natural isotopes, 184Os, and 186Os, have extremely long half-life (1.12×1013 years and 2×1015 years, respectively) and for practical purposes can be considered to be stable as well. 187Os is the daughter of 187Re (half-life 4.56×1010 years) and is most often measured in an 187Os/188Os ratio. This ratio, as well as the 187Re/188Os ratio, have been used extensively in dating terrestrial as well as meteoric rocks. It has also been used to measure the intensity of continental weathering over geologic time and to fix minimum ages for stabilization of the mantle roots of continental cratons. However, the most notable application of Os in dating has been in conjunction with iridium, to analyze the layer of shocked quartz along the Cretaceous–Paleogene boundary that marks the extinction of the dinosaurs 66 million years ago. There are also 30 artificial radioisotopes, the longest-lived of which is 194Os with a half-life of six years; all others have half-lives under 94 days. There are also nine known nuclear isomers, the longest-lived of which is 191mOs with a half-life of 13.10 hours. All isotopes and nuclear isomers of osmium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.
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Topic Review
ASTER (Spacecraft)
ASTER is a planned space mission under development by the Brazilian Space Agency that will launch a spacecraft to orbit a near-Earth object known as (153591) 2001 SN263, a triple asteroid system. The launch is scheduled for 2025, with a rendezvous in 2024/2027. According to de Brum et al. 2021, the launch is planned for June 2022 (asteroid arrival in December 2024) or June 2025 (arrival September 2027).
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Topic Review
Neutral Beam Injection
Neutral beam injection (NBI) is one method used to heat plasma inside a fusion device consisting in a beam of high-energy neutral particles that can enter the magnetic confinement field. When these neutral particles are ionized by collision with the plasma particles, they are kept in the plasma by the confining magnetic field, and can transfer most of their energy by further collisions with the plasma. By tangential injection in the torus, neutral beams also provide momentum to the plasma and current drive, one essential feature for long pulses of burning plasmas. Neutral beam injection is a flexible and reliable technique, which has been the main heating system on a large variety of fusion devices. To date, all NBI systems were based on positive precursor ion beams. In the 90s there has been impressive progress in negative ion sources and accelerators with the construction of multi-megawatt negative ion based NBI systems at LHD (H0, 180 keV) and JT-60U (D0, 500 keV). The NBI designed for ITER is a substantial challenge (D0, 1MeV, 40A) and a prototype is being constructed to optimize its performance in view of the ITER future operations. Other ways to heat plasma for nuclear fusion include RF heating, electron cyclotron resonance heating (ECRH), and ion cyclotron resonance heating (ICRH), Lower hybrid resonance heating (LH).
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Topic Review
Vat Purnima
Vat Purnima or pournima chavan or Wat Purnima (वट पूर्णिमा, vaṭapūrṇimā, also called Vat Savitri is a celebration observed by married women in the Western Indian states of Gujarat, Maharashtra, Goa and some regions of eastern Uttar Pradesh. On this Purnima or "full moon" during the three days of the month of Jyeshtha in the Hindu calendar (which falls in May-June in the Gregorian calendar) a married woman marks her love for her husband by tying a ceremonial thread around a banyan tree. The celebration is based on the legend of Savitri and Satyavan as narrated in the epic Mahabharata.
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Topic Review
Low-Energy Electron Microscopy
Low-energy electron microscopy, or LEEM, is an analytical surface science technique used to image atomically clean surfaces, atom-surface interactions, and thin (crystalline) films. In LEEM, high-energy electrons (15-20 keV) are emitted from an electron gun, focused using a set of condenser optics, and sent through a magnetic beam deflector (usually 60˚ or 90˚). The “fast” electrons travel through an objective lens and begin decelerating to low energies (1-100 eV) near the sample surface because the sample is held at a potential near that of the gun. The low-energy electrons are now termed “surface-sensitive” and the near-surface sampling depth can be varied by tuning the energy of the incident electrons (difference between the sample and gun potentials minus the work functions of the sample and system). The low-energy elastically backscattered electrons travel back through the objective lens, reaccelerate to the gun voltage (because the objective lens is grounded), and pass through the beam separator again. However, now the electrons travel away from the condenser optics and into the projector lenses. Imaging of the back focal plane of the objective lens into the object plane of the projector lens (using an intermediate lens) produces a diffraction pattern (low-energy electron diffraction, LEED) at the imaging plane and recorded in a number of different ways. The intensity distribution of the diffraction pattern will depend on the periodicity at the sample surface and is a direct result of the wave nature of the electrons. One can produce individual images of the diffraction pattern spot intensities by turning off the intermediate lens and inserting a contrast aperture in the back focal plane of the objective lens (or, in state-of-the-art instruments, in the center of the separator, as chosen by the excitation of the objective lens), thus allowing for real-time observations of dynamic processes at surfaces. Such phenomena include (but are not limited to): tomography, phase transitions, adsorption, reaction, segregation, thin film growth, etching, strain relief, sublimation, and magnetic microstructure. These investigations are only possible because of the accessibility of the sample; allowing for a wide variety of in situ studies over a wide temperature range. LEEM was invented by Ernst Bauer in 1962; however, not fully developed (by Ernst Bauer and Wolfgang Telieps) until 1985.
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Topic Review
Hinode
Hinode (/ˈhiːnoʊdeɪ/; Japanese: ひので, IPA: [çinode], Sunrise), formerly Solar-B, is a Japan Aerospace Exploration Agency Solar mission with United States and United Kingdom collaboration. It is the follow-up to the Yohkoh (Solar-A) mission and it was launched on the final flight of the M-V-7 rocket from Uchinoura Space Center, Japan on 22 September 2006 at 21:36 UTC (23 September, 06:36 JST). Initial orbit was perigee height 280 km, apogee height 686 km, inclination 98.3 degrees. Then the satellite maneuvered to the quasi-circular sun-synchronous orbit over the day/night terminator, which allows near-continuous observation of the Sun. On 28 October 2006, the probe's instruments captured their first images. The data from Hinode are being downloaded to the Norway , terrestrial Svalsat station, operated by Kongsberg a few kilometres west of Longyearbyen, Svalbard. From there, data was transmitted by Telenor through a fibre-optic network to mainland Norway at Harstad, and on to data users in North America, Europe and Japan.
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Topic Review
Virus Nanotechnology
Virus nanotechnology is the use of viruses as a source of nanoparticles for biomedical purposes. Viruses are made up of a genome and a capsid; and some viruses are enveloped. Most virus capsids measure between 20-500 nm in diameter. Because of their nanometer size dimensions, viruses have been considered as naturally occurring nanoparticles. Virus nanoparticles have been subject to the nanoscience and nanoengineering disciplines. Viruses can be regarded as prefabricated nanoparticles. Many different viruses have been studied for various applications in nanotechnology: for example, mammalian viruses are being developed as vectors for gene delivery, and bacteriophages and plant viruses have been used in drug delivery and imaging applications as well as in vaccines and immunotherapy intervention.
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Topic Review
Physicist and Christian
Physicist and Christian: A Dialogue Between the Communities (1961) is a book by William G. Pollard. Much of the attention given to the book such as its review in Time (magazine) magazine has been attributed to the fact that Pollard was not only a well-respected physicist but also an Anglican priest. The book deliberately avoids specific subject matter differences, focusing on religion and science both as human communities. An important theme is the idea that human knowledge—scientific or religious—can be developed only by those, like Pollard, who have "fully and freely" given themselves to a human community, whether to the physics community or Christian community or some other, e.g., the United States Marine Corps. Also an important theme is Pollard's argument and cautions against a cultural norm in which scientific knowledge would be objective and public, on the one hand, while religious knowledge would be subjective and private, on the other.
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Topic Review
Timoshenko Beam Theory
The Timoshenko beam theory was developed by Stephen Timoshenko early in the 20th century. The model takes into account shear deformation and rotational bending effects, making it suitable for describing the behaviour of thick beams, sandwich composite beams, or beams subject to high-frequency excitation when the wavelength approaches the thickness of the beam. The resulting equation is of 4th order but, unlike Euler–Bernoulli beam theory, there is also a second-order partial derivative present. Physically, taking into account the added mechanisms of deformation effectively lowers the stiffness of the beam, while the result is a larger deflection under a static load and lower predicted eigenfrequencies for a given set of boundary conditions. The latter effect is more noticeable for higher frequencies as the wavelength becomes shorter (in principle comparable to the height of the beam or shorter), and thus the distance between opposing shear forces decreases. If the shear modulus of the beam material approaches infinity—and thus the beam becomes rigid in shear—and if rotational inertia effects are neglected, Timoshenko beam theory converges towards ordinary beam theory.
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