Mercury-in-glass thermometer related to the rapid cooling (and contraction) of the glass. When Celsius decided to use his own temperature scale, he originally defined his scale "upside-down", i.e. he chose to set the boiling point of pure water at 0 °C (212 °F) and the freezing point at -100 °C (-32 °F). One year later, Frenchman Jean-Pierre Christin proposed to invert the scale with the freezing point at and the boiling point at . He named it Centigrade (100 grades). Finally, Celsius proposed a method of calibrating a thermometer: These points are adequate for approximate calibration but both vary with atmospheric pressure.
IbpB thermometer IbpB thermometer The IbpB thermometer is an RNA thermometer element found in the "ibpAB" operon. The operon contains two heat-shock genes, encoding inclusion body binding proteins A and B (IbpA/B), and is the most drastically upregulated operon under heat-shock in "Escherichia coli". "IbpA" is regulated by a ROSE element found in its 5' UTR, while "IbpB" has its own heat-sensitive cis-regulatory element. The activity of this thermoregulator was confirmed "in vitro" but was not found "in vivo", suggesting more complicated operon regulation exists in bacterial cells. The IbpB protein, whose expression is regulated by the IbpB thermometer, is 48% identical