In certain industries, such as oil and gas, concentration is especially acute, with only two or three auditors ruling the market.

ECONOMIST: Auditing

Thus, over the course of a few decades, the concentration of the gas in the atmosphere will return to pre-industrial levels.

ECONOMIST: Using the sea to grow biofuel

Climate sensitivity is a key parameter for estimating the long-term temperature increase expected from a doubling of the concentration of greenhouse gas emissions in the atmosphere.

FORBES: Climate Sins and the High Priests of Peer Review

The bestial treatment of slave labourers in concentration camps, and the use of gas chambers, are commonly seen as the epitomes of Nazi persecution.

ECONOMIST: How Stalin and Hitler enabled each other��s crimes

"Rising imports of oil and gas into OECD regions and developing Asia, together with the growing concentration of production in a small number of countries, would increase our susceptibility to supply disruptions and sharp price hikes, " Tanaka said.

CNN: Report urges fuel revolution

It takes a certain minimum level of helium concentration to make it economically viable to separate out the helium from the natural gas.

CNN: U.S. needs a strategy on helium

The concentration of xenon was eight times higher than normal, and the presence of the gas is indicative of nuclear activities.

FORBES: Magazine Article