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Creation and annihilation operators. Creation operators and annihilation operators are mathematical operators that have widespread applications in quantum mechanics, notably in the study of quantum harmonic oscillators and many-particle systems. [1] An annihilation operator (usually denoted ) lowers the number of particles in a given state by one.
Another type of operator in quantum field theory, discovered in the early 1970s, is known as the anti-symmetric operator. This operator, similar to spin in non-relativistic quantum mechanics is a ladder operator that can create two fermions of opposite spin out of a boson or a boson from two fermions. A Fermion, named after Enrico Fermi, is a ...
Retro-Diels–Alder reaction. The retro-Diels–Alder reaction (rDA reaction) is the reverse of the Diels–Alder (DA) reaction, a [4+2] cycloelimination. It involves the formation of a diene and dienophile from a cyclohexene. It can be accomplished spontaneously with heat, or with acid or base mediation. [1][2]
Tetracycline-controlled transcriptional activation. Example of a T-REx system controlling the expression of shRNA. Tetracycline-controlled transcriptional activation is a method of inducible gene expression where transcription is reversibly turned on or off in the presence of the antibiotic tetracycline or one of its derivatives (e.g. doxycycline).
An operator that has a unique self-adjoint extension is said to be essentially self-adjoint; equivalently, an operator is essentially self-adjoint if its closure (the operator whose graph is the closure of the graph of ) is self-adjoint. In general, a symmetric operator could have many self-adjoint extensions or none at all.
Mercury-Redstone 3. Mercury-Redstone 3, or Freedom 7, was the first United States human spaceflight, on May 5, 1961, piloted by astronaut Alan Shepard. It was the first crewed flight of Project Mercury. The project had the ultimate objective of putting an astronaut into orbit around the Earth and returning him safely.
Tandy/Radio Shack TRS-80 Model I. In the mid-1970s, Tandy Corporation's Radio Shack division was a successful American chain of more than 3,000 electronics stores. Among the Tandy employees who purchased a MITS Altair kit computer was buyer Don French, who began designing his own computer and showed it to the vice president of manufacturing John V. Roach, Tandy's former electronic data ...
Retrosynthetic analysis. Retrosynthetic analysis is a technique for solving problems in the planning of organic syntheses. This is achieved by transforming a target molecule into simpler precursor structures regardless of any potential reactivity/interaction with reagents. Each precursor material is examined using the same method.