Marine planktonic organisms, 0.2–2.0 μm in size, and consisting mainly of bacteria and cyanobacteria.

Mineral, FeO(OH).nH2O; sp. gr. 2.7–4.3; hardness 4.0–5.3; yellowish-brown to reddish-brown; normally earthy lustre; usually amorphous; occurs as a secondary mineral from the weathering of iron in ...

The time taken for a seismic P-wave to travel through one foot (0.3048 m), measured by a sonic log in units of μs/foot.

The partial differential equation:∂2u/∂x2 + ∂2u/∂y2 + ∂2u/∂z2 = 0It may also be written in the form ∇2u = 0, where ∇2 is called the Laplace operator. It was formulated by the French mathematician P. ...

The pigment that acts as the energy trap of photosystem I in chloroplasts. It is thought to be chlorophyll a in a special structural environment. It represents about 0.3 per cent of the total ...

The volume of a fixed mass of gas at constant pressure expands by a constant fraction of its volume at 0°C for each Celsius degree or kelvin its temperature is raised. For any ideal gas the fraction ...

The narrow gap, typically 0.02 micrometres wide, between a presynaptic neuron and a postsynaptic neuron, muscle, or gland at a synapse (1).

Describing elements that tend to gain electrons and form negative ions. The halogens are typical electronegative elements. For example, in hydrogen chloride, the chlorine atom is more electronegative ...

1. (in physics) Symbol P. The rate at which work is done or energy is transferred. In SI units it is measured in watts (joules per second). See also horsepower.2. (in mathematics) The number of times ...

Symbol mol. The SI unit of amount of substance. It is equal to the amount of substance that contains as many elementary units as there are atoms in 0.012 kg of carbon–12. The elementary units may be ...

A group of monatomic gaseous elements forming group 18 (formerly group 0) of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). The electron ...

A condition of a system in which it has a precarious stability that can easily be disturbed. It is unlike a state of stable equilibrium in that a minor disturbance will cause a system in a metastable ...

A measure of a system's ability to do work. The Gibbs free energy (or Gibbs function), G, is defined by G = H – TS, where G is the energy liberated or absorbed in a reversible process at constant ...

...f ( x ) = a 0 / 2 + ∑ n = 1 ∞ ( a n cos n x + b n sin n x ) A series of this type is called a Fourier series . If the function is periodic with a period 2 π , the coefficients a 0 , a n , b n are: a 0 = ∫ - π + π f ( x ) d x , a n = ∫ - π + π f ( x ) cos n x d x , ( n = 1 , 2 , 3 , … ) , b n = ∫ - π + π 1 / π f ( x ) sin n x d x , ( n = 1 , 2 , 3 , .… ) . Fourier analysis and Fourier series are named after the French mathematician and engineer Joseph Fourier ( 1768–1830 ). Fourier series have many important applications in mathematics, science, and...