Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Hottest Latest Alphabetical (A-Z) Alphabetical (Z-A)
Type:
All Topic Review Biography
Topic Review
Aquila
Aquila, a constellation in the northern celestial hemisphere, is renowned for its striking resemblance to an eagle soaring through the heavens. Designated by the International Astronomical Union (IAU), Aquila captivates observers with its prominent stars and rich astronomical history, making it a prominent feature in both ancient mythology and modern astronomy.
  • 322
  • 29 Feb 2024
Topic Review
Belgrade Observatory
Belgrade Observatory is an astronomical observatory located in the eastern part of Belgrade, Serbia, in the natural environment of Zvezdara Forest.
  • 322
  • 18 Oct 2022
Topic Review
SDSS J001820.5-093939.2
SDSS J001820.5–093939.2 or SDSS J0018-0939 for short is a star system approximately 1000 light-years away near the constellation Cetus. SDSS J0018-0939 is a cool main-sequence star. It is the first star found proposed to be a massive second generation star.
  • 321
  • 18 Oct 2022
Topic Review
Quantum Information Education
Quantum information is an emerging scientific and technological discipline attracting a growing number of professionals from various related fields. Although it can potentially serve as a valuable source of skilled labor, the Internet provides a way to disseminate information about education, opportunities, and collaboration.
  • 320
  • 12 May 2023
Topic Review
Earth Hour
Earth Hour is a worldwide movement organized by the World Wildlife Fund (WWF). The event is held annually, encouraging individuals, communities, and businesses to turn off non-essential electric lights, for one hour, from 8:00 to 9:00 p.m. on the last Saturday of March, as a symbol of commitment to the planet. It was started as a lights-off event in Sydney, Australia, in 2007. Occasionally, in years when Holy Saturday falls on the last Saturday of March, Earth Hour is moved a week early rather than its usual date.
  • 319
  • 14 Oct 2022
Topic Review
Silicon Photonics Technology
Silicon (Si) photonics is a groundbreaking technology that merges the fields of Si microelectronics and photonics to enable the manipulation and transmission of light on a Si chip. It leverages the exceptional properties of Si, such as its high refractive index and compatibility with existing electronic manufacturing processes, to create compact and highly efficient optical devices. Silicon photonics has been an area of active research and development. Researchers have been working on enhancing the integration density and intricacy of silicon photonic circuits. This involves the development of advanced fabrication techniques and novel designs to enable more functionalities on a single chip, leading to higher performance and more efficient systems. 
  • 318
  • 22 Aug 2023
Topic Review
Osmium-173
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.
  • 318
  • 27 Oct 2022
Topic Review
Antlia
Antlia is a constellation recognized by the International Astronomical Union (IAU), situated in the southern celestial hemisphere. Named after the air pump, it is a relatively faint constellation with no stars brighter than fourth magnitude, but it contains several interesting deep-sky objects, including the Antlia Galaxy Cluster, making it a fascinating subject for exploration by astronomers.
  • 317
  • 15 Mar 2024
Topic Review
Prism Adaptation
Prism adaptation is a sensory-motor adaptation that occurs after the visual field has been artificially shifted laterally or vertically. It was first introduced by Hermann von Helmholtz in late 19th-century Germany as supportive evidence for his perceptual learning theory (Helmholtz, 1909/1962). Since its discovery, prism adaptation has been suggested to improve spatial deficits in patients with unilateral neglect.
  • 317
  • 24 Nov 2022
Topic Review
Fresnel Imager
A Fresnel imager is a proposed ultra-lightweight design for a space telescope that uses a Fresnel array as primary optics instead of a typical lens. It focuses light with a thin opaque foil sheet punched with specially shaped holes, thus focusing light on a certain point by using the phenomenon of diffraction. Such patterned sheets, called Fresnel zone plates, have long been used for focusing laser beams, but have so far not been used for astronomy. No optical material is involved in the focusing process as in traditional telescopes. Rather, the light collected by the Fresnel array is concentrated on smaller classical optics (e.g. 1/20th of the array size), to form a final image. The long focal lengths of the Fresnel imager (a few kilometers) require operation by two-vessel formation flying in space at the L2 Sun-Earth Lagrangian point. In this two spacecraft formation-flying instrument, one spacecraft holds the focussing element: the Fresnel interferometric array; the other spacecraft holds the field optics, focal instrumentation, and detectors.
  • 317
  • 01 Nov 2022
  • Page
  • of
  • 131
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
ScholarVision Creations
Feedback