# lambda; Λ, λ +

#### (Greek: the eleventh letter of the Greek alphabet; Λ, λ)

lambda
1. The 11th letter of the Greek alphabet (Λ, λ), represented in the English alphabet as "L, l".
2. The point of junction at the center of the back of the cranium (skull) between the rear plate of the cranium occipital bone and the two upper plates parietal bones.

This junction is said to resemble the Greek capital letter lambda.
3. The craniometric point at the junction of the sagittal and lamboid sutures of the skull.
4. The point at the site of the posterior fontanel where the lambdoid and sagittal sutures meet; used as a craniometric landmark.

lambda calculus
A mathematical formalization of the rules of substitution; used for modeling the process of substituting values for bound variables.
lambda chain, lambda chains
1. A type of light polypeptide chain found in immunoglobulin molecules.
2. One of the two forms of smaller polypeptide chains (known as light chains) that occur in immunoglobulins.
lambda circuit
An individual wavelength of light for transmitting data on a strand of fiber-optic cable.

Using separate lasers, each tuned to a slightly different frequency, multiple lambdas can be projected down a single fiber strand to carry multiple streams of data.

DWDM (dense wavelength division multiplexing) is the technology for projecting multiple lambda circuits on fiber strands. Currently, 200 lambdas per fiber is common, but thousands are possible.

lambda dispatch
The solution of the problem of finding the most economical use of generators to supply a given quantity of electric power, using the method of Lagrange multipliers, which are symbolized λ.
lambda hyperon, lambda particle
1. A quasi-stable baryon, forming an isotopic singlet, having zero charge and hypercharge.
2. Any baryon resonance having zero hypercharge and total isotopic spin.
lambda phage
A temperate bacterial virus that infects Escherichia coli and is able to integrate into the host DNA or to initiate a lytic cycle, copying its own genetic information, lysing the host cell, and releasing new viruses.

Used as a model vector in gene cloning.

lambda point
1. The transition temperature, approximately 2.19 K. below which helium I changes into helium II.
2. The temperature at which the specific heat of a substance has a sharp peak.

This is observed in many second-order transitions.

lambda sulfur
One of the two components of plastic (or gamma) sulfur; soluble in carbon disulfide.
lambda wave
A low-voltage occipital wave recorded by electroencephalography during visual activity.
lambdacism, paralambdacism
1. A speech disorder consisting of the substitution of "L" for "R".
2. A speech disorder involving the faulty pronunciation of "L"; babbling speech.
3. The substitution of "L" for "R" when speaking.
lambdoid, lambdoidal
1. Shaped like the Greek letter Λ or λ.
2. Resembling in form the Greek letter lambda (Λ); a reference to the suture between the occipital and the two parietal bones of the skull.
lambdoidal suture
The interdigitating connection between the occipital bone and the parietal bones of the skull.

It is continuous with the occipitomastoid suture between the occipital and the mastoid portions of the temporal bones.