Lower Case
The lower-case letter η is used as a symbol in:
- Thermodynamics, the efficiency of a Carnot heat engine.
- Chemistry, the hapticity, or the number of atoms of a ligand attached to one coordination site of the metal in a coordination compound. For example, an allyl group can coordinate to palladium in the η¹ mode (only one atom of an allyl group attached to palladium) or the η³ mode (3 atoms attached to palladium).
- Optics, the electromagnetic impedance of a medium, or the quantum efficiency of detectors.
- Particle physics, to represent the η mesons.
- Experimental particle physics, η stands for pseudorapidity.
- Cosmology, η represents conformal time; dt = adη.
- Relativity and Quantum field theory (physics), η (with two subscripts) represents the metric tensor of Minkowski space (flat spacetime).
- Statistics, η2 is the "partial regression coefficient". η is the symbol for the linear predictor of a generalized linear model, and can also be used to denote the median of a population.
- Economics, η is the elasticity.
- Astronomy, the seventh brightest (usually) star in a constellation. See Bayer designation.
- Mathematics, η-conversion, see lambda calculus
- Mathematics, the Dirichlet eta function, Dedekind eta function, and Weierstrass eta function.
- Biology, a DNA polymerase found in higher eukaryotes and implicated in Translesion Synthesis.
- Neural network backpropagation, η stands for the learning rate.
- Telecommunications, Eta stands for efficiency
- Electronics, η stands for the ideality factor of a bipolar transistor, and has a value close to 1.000. It appears in contexts where the transistor is used as a temperature sensing device, e.g. the thermal "diode" transistor that is embedded within a computer's microprocessor.
- Power electronics, η stands for the efficiency of a power supply, defined as the output power divided by the input power.
- Atmospheric science, η represents absolute atmospheric vorticity.
- Rheology, η represents viscosity.
- Oceanography, η is the measurement (usually in metres) of sea-level height above or below the mean sea-level at that same location.
Famous quotes containing the word case:
“Oh, that I knew where I might find him, that I might come even to his dwelling! I would lay my case before him, and fill my mouth with arguments. I would learn what he would answer me, and understand what he would say to me. Would he contend with me in the greatness of his power? No; but he would give heed to me. There an upright person could reason with him, and I should be acquitted forever by my judge.”
—Bible: Hebrew, Job 23:3-7.
Job, of God.
“Consider the deference which is everywhere paid to a doctor’s opinion. Nothing more strikingly betrays the credulity of mankind than medicine. Quackery is a thing universal, and universally successful. In this case it becomes literally true that no imposition is too great for the credulity of men.”
—Henry David Thoreau (1817–1862)