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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A quantum-mechanical variable or quantum number applied to quarks and their compounds, the strongly interacting fundamental hadrons, and the compounds of those hadrons (such as nuclear states) to facilitate consideration of the consequences of the charge independence of the strong (nuclear) forces. This variable is also known as isotopic spin, isobaric spin, and isospin.
Industry:Science
A quantum-mechanical variable that specifies the component of spin-angular momentum of a particle along its direction of motion. The helicity of a particle with rest mass depends on the reference frame, because such a particle has velocity less than the velocity of light <i>c</i> in vacuum. Hence one can make a Lorentz transformation along the direction of motion to a frame in which the particle moves in the opposite direction. For a massless particle, reversal in direction of motion by Lorentz transformation is impossible, and helicity is a Lorentz-invariant quantity. For example, a beam of circularly polarized light consists of photons (zero-mass quanta of the electromagnetic field) with helicity <i>h</i> = +1 for right circular polarization, or <i>h</i> = −1 for left circular polarization (see <b>illustration</b>).
Industry:Science
A quasiparticle that forms from an electronic charge carrier interacting with a solid's vibrating displaceable atoms. In particular, a polaron comprises an electronic charge carrier together with the carrier-induced altered motions of surrounding atoms. Different classes of material have distinct types of polarons. Polarons may be divided into weak-coupling polarons and strong-coupling polarons. Strong-coupling polarons comprise large self-trapped polarons and small self-trapped polarons.
Industry:Science
A quasistable entity of nuclear dimensions formed in nuclear collisions and comprising two or more discrete nuclei that retain their identities and are bound together by strong nuclear forces. Whereas the stable molecules of chemistry and biology consist of atoms bound through various electronic mechanisms, nuclear molecules do not form in nature except possibly in the hearts of giant stars; this simply reflects the fact that all nuclei carry positive electrical charges, and that under all natural conditions the long-range electrostatic repulsion prevents nuclear components from coming within the grasp of the short-range attractive nuclear force which could provide molecular binding. But in energetic collisions this electrostatic repulsion can be overcome.
Industry:Science
A queue (or a waiting line) is a familiar concept. We experience queues at the checkout counter of the grocery store, at the movie theater, in traffic, or in other daily activities. Queues also exist in the provision of health care. Large health-care concerns, such as clinics, hospitals, or entire health-care systems, are most appropriately viewed as a network of queues.
Industry:Science
A radar in which the transmitter output is uninterrupted, in contrast to pulse radar, where the output consists of short pulses. Among the advantages of continuous-wave (CW) radar is its ability to measure velocity with extreme accuracy by means of the Doppler shift in the frequency of the echo. The detected, reflected wave is shifted in frequency by an amount which is a function of the relative velocity between the target and the transmitter-receiver. Range data are extracted from the change in Doppler frequency with time.
Industry:Science
A radar system used to measure the relative velocity of the system and the radar target. The operation of these systems is based on the fact that the Doppler frequency shift in the target echo is proportional to the radial component of target velocity.
Industry:Science
A radioactive isotope (as distinguished from a stable isotope) of an element. Atomic nuclei are of two types, unstable and stable. Those in the former category are said to be radioactive and eventually are transformed, by radioactive decay, into the latter. One of the three types of particles or radiation (alpha particles, beta particles, and gamma rays) is emitted during each stage of the decay.
Industry:Science
A radioactive isotope used in studying living systems. This article discusses the use of radioactive isotopes in the investigation of metabolic processes.
Industry:Science
A radioactive isotope which, when injected into a chemically similar substance or artificially attached to a biological or physical system, can be traced by radiation detection devices. Many problems in biology, medicine, and industrial engineering not amenable to other approaches can be solved by the use of these tracers.
Industry:Science
