Where does nucleus collide?

The compartment inside a eukaryotic cell that holds the chromosomes and is wrapped in a double membrane. Robert Brown's 1833 On the organs and mode of fecundation in Orchideæ and Asclepiadeæ named the nucleus as the constant rounded body he saw inside plant cells, from observations he made in 1831. The referent is a physical organelle in a living cell, usually one per cell and measured in micrometres, not the core of an atom, a speck that seeds a raindrop, or the central sound of a spoken syllable.[1]

Unit

One organelle per cell, on the order of micrometres across

Recovery means

The membrane breaks down at cell division and reassembles around the separated chromosomes

Measured by

Seen and sized under light or electron microscopy and marked by stains that bind DNA

The tiny central body of an atom that carries its positive charge and almost all of its mass, built from protons and neutrons. Rutherford's 1911 The scattering of α and β particles by matter and the structure of the atom showed, from how particles bounced off gold foil, that the charge and mass sit in a minute core, which came to be called the atomic nucleus. The referent is a subatomic core measured in femtometres, not an organelle in a cell, a droplet seed in the air, or the central sound of a syllable.[2]

Unit

One core per atom, on the order of femtometres across

Recovery means

Not applicable

Measured by

Probed by scattering experiments and described by charge, mass number, and binding energy

The small airborne particle onto which water vapour condenses to begin a cloud or fog droplet. Köhler's 1936 The nucleus in and the growth of hygroscopic droplets set out the physics of how a soluble particle takes up water and grows once the air is humid enough. The referent is a microscopic seed particle suspended in the atmosphere, counted per cubic centimetre of air, not the core of an atom, a body inside a cell, or the central sound of a syllable.[3]

Unit

One seed particle per droplet, typically sub-micrometre in size

Recovery means

Not applicable

Measured by

Counted with a condensation particle counter and described by size and how readily it takes up water

The central, usually vowel-like sound that every syllable is built around and cannot do without. Fudge's 1969 Syllables analysed the syllable as an internal structure organised around an obligatory peak, and Clements and Keyser's 1983 CV phonology gave a standard generative account in which this core position is the nucleus, flanked by any opening and closing consonants. The referent is a position in the sound structure of a spoken syllable, not the core of an atom, a body inside a cell, or a particle that seeds a droplet.[4][5]

Unit

One obligatory core position per syllable

Recovery means

Not applicable

Measured by

Identified by phonological analysis of syllable structure and by acoustic prominence such as loudness and duration