The term closed system has different meanings in different contexts.

In thermodynamics, a closed system can exchange energy (as heat or work), but not matter, with its surroundings. In contrast, an isolated system cannot exchange any of heat, work, or matter with the surroundings, while an open system can exchange all of heat, work and matter. For a simple system, with only one type of particle (atom or molecule), a closed system amounts to a constant number of particles. However, for systems which are undergoing a chemical reaction, there may be all sorts of molecules being generated and destroyed by the reaction process. In this case, the fact that the system is closed is expressed by stating that the total number of each elemental atom is conserved, no matter what kind of molecule it may be a part of. Mathematically:

Failed to parse (Missing texvc executable; please see math/README to configure.): \sum_{j=1}^m a_{ij}N_j=b_i

where Failed to parse (Missing texvc executable; please see math/README to configure.): N_j

Kelley Polar, born Michael Kelley, is an alternative dance vocalist and producer.

Originally a classical violist from Providence, R.I., he studied at the Oberlin Conservatory and then at Juilliard, where he collaborated with Metro Area's Darshan Jesrani and Morgan Geist on tracks like "Miura", "The Art of Hot" and "Caught Up". He released a number of solo EPs under the alias of the Kelley Polar Quartet on Environ Records. His first album as Kelley Polar, Love Songs of the Hanging Gardens, was released in 2005 and contains elements of house, disco and pop. His follow up I Need You To Hold On While The Sky Is Falling was released in March 2008 in the US and most of Europe.

He is the brother of Blevin Blectum. As Mike Kelley, he is the violist for the Apple Hill Chamber Players.

† As Kelley Polar Quartet