A bacterial-type plastid RNA polymerase with core subunits encoded by the plastid genome. Nuclear-encoded sigma factors and associated components mean that its name does not imply autonomous regulation.

A nuclear-specified plastid RNA polymerase of the phage-type family, with promoter preferences distinct from plastid-encoded RNA polymerase.

Regulation directed from the nuclear system toward an organelle, including control of imported regulators. It contrasts with retrograde signaling in direction, not necessarily in timescale.

Regulation of nuclear gene expression in response to the state of an organelle. The identity and route of a signal require experimental evidence beyond correlation of nuclear and organellar changes.

A nuclear-encoded plastid factor implicated in coordination of plastid state with nuclear gene expression. It should not be identified with every exported plastid stress signal.^[ref]

Temporal sensing in bacterial chemotaxis compares changing stimulation during movement with a recent adapted baseline. Attractant increases can lengthen runs and decreases can increase tumbling, producing biased movement up a chemical gradient. Rapid spatially uniform concentration steps distinguish a temporal response from a requirement for front-to-back spatial comparison.^[ref]

A chemoattractant is a substance whose spatial distribution can bias responsive biological cells to migrate towards higher concentration. A directional response to its gradient is chemotaxis; a change only in movement speed does not by itself establish a directional response.

Carbon-end bonding of CO to Pt can combine donation from a molecular sigma orbital with metal-to-CO pi back-donation. The resulting hybridization and local-potential changes can shift the Pt core binding energy and modify the molecule's vibrational spectrum. A measured core-level shift includes core-hole screening and does not uniquely specify a net transferred charge.

For $X\rightleftharpoons Y$ with forward and reverse first-order rates $a,b$, the closed-family partition relaxes at rate $a+b$. Adding losses changes the relaxation eigenvalues. If family abundance evolves much more slowly, a quasi-equilibrium ratio can be useful; setting the entire family derivative to zero needs a separate timescale comparison.

In a simple stratospheric model, hydroxyl and hydroperoxyl radicals interconvert rapidly. Their total abundance is controlled by slower sources and termination reactions. Atomic hydrogen can be included in a broader family definition when its chemistry is treated explicitly.

Suppose a reduced steady balance is $P=A{X}^2+BX$, where $X=[{\mathrm{O}}_3]$, and hold $P$ and all specified background concentrations fixed. With $u=1/T$, $d\ln A/du=-a$ and $d\ln B/du=-b$, implicit differentiation gives $d\ln X/du=(aA{X}^2+bBX)/(2A{X}^2+BX)$. The quadratic loss term includes temperature-dependent O/O3 partitioning as well as the direct reaction coefficient. Holding the loss ratio fixed over a finite change is an additional approximation; solving the new quadratic provides a check.