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
Equatorial Coordinate System
The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects. It may be implemented in spherical or rectangular coordinates, both defined by an origin at the centre of Earth, a fundamental plane consisting of the projection of Earth's equator onto the celestial sphere (forming the celestial equator), a primary direction towards the vernal equinox, and a right-handed convention. The origin at the centre of Earth means the coordinates are geocentric, that is, as seen from the centre of Earth as if it were transparent. The fundamental plane and the primary direction mean that the coordinate system, while aligned with Earth's equator and pole, does not rotate with the Earth, but remains relatively fixed against the background stars. A right-handed convention means that coordinates increase northward from and eastward around the fundamental plane.
  • 1.3K
  • 16 Nov 2022
Topic Review
Soyuz TM-21
Soyuz TM-21 was a crewed Soyuz spaceflight to Mir. The mission launched from Baikonur Cosmodrome, atop a Soyuz-U2 carrier rocket, at 06:11:34 UTC on March 14, 1995. The flight marked the first time thirteen humans were flying in space simultaneously, with three aboard the Soyuz, three aboard Mir and seven aboard Space Shuttle Endeavour, flying STS-67. The spacecraft carried expedition EO-18 to the space station. This included the first American astronaut to launch on a Soyuz spacecraft and board Mir, Norman Thagard, for the American Thagard Increment aboard the station, which was the first Increment of the Shuttle-Mir program. The three crew members it launched were relieved by Space Shuttle Atlantis during STS-71, when they were replaced by expedition EO-19. The crew returned to earth aboard Soyuz TM-21 on September 11, 1995.
  • 297
  • 16 Nov 2022
Biography
Ashoke Sen
Ashoke Sen, FRS (/əˈʃoʊk sɛn/; born 1956) is an Indian theoretical physicist and distinguished professor at the Harish-Chandra Research Institute, Allahabad.[1] He is also an honorary fellow in National Institute of Science Education and Research (NISER), Bhubaneswar, India [2] and also a Morningstar Visiting professor at MIT and a distinguished professor at the Korea Institute for Advanced
  • 1.7K
  • 16 Nov 2022
Topic Review
Radiative Transfer Equation and Diffusion Theory for Photon Transport in Biological Tissue
The RTE can mathematically model the transfer of energy as photons move inside a tissue. The flow of radiation energy through a small area element in the radiation field can be characterized by radiance [math]\displaystyle{ L(\vec{r},\hat{s},t) (\frac{W}{m^2 sr}) }[/math]. Radiance is defined as energy flow per unit normal area per unit solid angle per unit time. Here, [math]\displaystyle{ \vec{r} }[/math] denotes position, [math]\displaystyle{ \hat{s} }[/math] denotes unit direction vector and [math]\displaystyle{ t }[/math] denotes time. 
  • 1.3K
  • 16 Nov 2022
Biography
William T. Kane
William T. Kane (September 8, 1932 – September 23, 2008) was a physicist for Corning Incorporated, formerly Corning Glass Works, Inc., in Corning, New York, who held patents in crystallography and heat-sensing technology—developments which contributed to the early processing and manufacture of fiber optics. He was also the Corning representative for the establishment of international standar
  • 457
  • 16 Nov 2022
Topic Review
Frequency
Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. Frequency is measured in units of hertz (Hz) which is equal to one occurrence of a repeating event per second. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example: if a newborn baby's heart beats at a frequency of 120 times a minute (2 hertz), its period, T, — the time interval between beats—is half a second (60 seconds divided by 120 beats). Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light.
  • 4.2K
  • 16 Nov 2022
Topic Review
Node
A node is a point along a standing wave where the wave has minimum amplitude. For instance, in a vibrating guitar string, the ends of the string are nodes. By changing the position of the end node through frets, the guitarist changes the effective length of the vibrating string and thereby the note played. The opposite of a node is an anti-node, a point where the amplitude of the standing wave is at maximum. These occur midway between the nodes.
  • 555
  • 16 Nov 2022
Biography
Clyde Cowan
Clyde Lorrain Cowan Jr (December 6, 1919 in Detroit, Michigan – May 24, 1974 in Bethesda, Maryland) was an American physicist, the co-discoverer of the neutrino along with Frederick Reines. The discovery was made in 1956 in the neutrino experiment.[1] Frederick Reines received the Nobel Prize in Physics in 1995 in both their names. Born the oldest of four children in Detroit, Michigan, Cowa
  • 791
  • 15 Nov 2022
Topic Review
High-Resolution Transmission Electron Microscopy
High-resolution transmission electron microscopy is an imaging mode of specialized transmission electron microscopes that allows for direct imaging of the atomic structure of samples. It is a powerful tool to study properties of materials on the atomic scale, such as semiconductors, metals, nanoparticles and sp2-bonded carbon (e.g., graphene, C nanotubes). While this term is often also used to refer to high resolution scanning transmission electron microscopy, mostly in high angle annular dark field mode, this article describes mainly the imaging of an object by recording the two-dimensional spatial wave amplitude distribution in the image plane, in analogy to a "classic" light microscope. For disambiguation, the technique is also often referred to as phase contrast transmission electron microscopy. At present, the highest point resolution realised in phase contrast transmission electron microscopy is around 0.5 ångströms (0.050 nm). At these small scales, individual atoms of a crystal and its defects can be resolved. For 3-dimensional crystals, it may be necessary to combine several views, taken from different angles, into a 3D map. This technique is called electron crystallography. One of the difficulties with high resolution transmission electron microscopy is that image formation relies on phase contrast. In phase-contrast imaging, contrast is not intuitively interpretable, as the image is influenced by aberrations of the imaging lenses in the microscope. The largest contributions for uncorrected instruments typically come from defocus and astigmatism. The latter can be estimated from the so-called Thon ring pattern appearing in the Fourier transform modulus of an image of a thin amorphous film.
  • 963
  • 15 Nov 2022
Biography
Valery Rubakov
Valery Anatolyevich Rubakov (Russian: Валерий Анатольевич Рубаков, born 16 February 1955 in Moscow, USSR) is a Russian theoretical physicist. His scientific interests include quantum field theory, elementary particle physics, and cosmology. He is affiliated with the Institute for Nuclear Research (INR) of the Russian Academy of Sciences in Moscow. Rubakov studied phys
  • 601
  • 15 Nov 2022
  • Page
  • of
  • 130
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
Video Production Service
Feedback