An O-silylated ester enolate, with two oxygen substituents on one carbon of the enol double bond.

A cage ${\mathrm{R}}_8\mathrm{S}{\mathrm{i}}_8{\mathrm{O}}_{12}$ represented by a cube of eight silicon vertices with one bridging oxygen on each of twelve edges.

A cage ${\mathrm{R}}_{10}\mathrm{S}{\mathrm{i}}_{10}{\mathrm{O}}_{15}$ with a common pentagonal-prismatic silicon skeleton and an oxygen bridge on each edge.

A corner-deficient cage ${\mathrm{R}}_7\mathrm{S}{\mathrm{i}}_7{\mathrm{O}}_9(\mathrm{OH}{)}_3$. Removing one silicon corner from a T8 cage leaves three silanol-bearing silicon sites, three further sites adjacent to those, and a unique opposite site: symmetry classes 3:3:1.

A coordination ligand containing deprotonated silanol oxygen, $\mathrm{Si}-{\mathrm{O}}^{-}$, which binds a metal through oxygen. Three silanol groups on a corner-deficient silsesquioxane can give a facial tridentate trianionic donor set.

A signal whose relation to the advertised property is constrained by its production mechanism. The receiver’s use and the relevant physical constraint should both be tested.

Signalling in which costs contribute to the evolutionary incentives governing expression. Reliability depends on differences in net payoffs among signaller types, not merely on a signal being expensive.

Contingent communication among siblings about their willingness to contest a resource, potentially reducing unnecessary competitive costs.

Killing of a sibling, whose ecological and evolutionary explanations depend on resource limitation, asymmetry and the consequences for survivors and parents.

A decline in the number of surviving offspring within a brood, often associated with limited provisioning. The occurrence of brood reduction alone does not establish an adaptive parental or offspring strategy.

Independent arrivals of charges $q$ at rate $\lambda$ give a Poisson distribution for the number $N$ in time $\tau$, with mean and variance $\lambda \tau$. Since ${\overline{I}}_{\tau }=qN/\tau$ and $I=q\lambda$, its variance is $qI/\tau$. This agrees with integrating the one-sided shot noise power spectral density $2qI$ through the averaging filter: its effective noise bandwidth is $1/(2\tau )$. A two-sided convention instead assigns density $qI$ to each sign of frequency.

For independent photon detections with a fixed mean rate, counts in a fixed exposure have a Poisson distribution, so the variance equals the mean. Multiplying by a representative photon energy gives ${\sigma }_E=h\nu \sqrt{N}$. A source-only signal-to-noise threshold $q$ therefore needs an expected $N=q^2$ photons. Background, detector noise, variable illumination and photon correlations can invalidate that source-only formula.

A graph path of minimum total edge weight between its endpoints, among the permitted paths. In an unweighted graph, its weight is the number of edges. A shortest path need not be unique.

An empirical orbital-screening prescription. Other electrons in an $ns,np$ group count $0.35$ each; electrons in shell $n-1$ count $0.85$, deeper electrons $1.00$, and outer electrons zero. For $1s$, the partner contributes $0.30$. d and f groups use separate rules.^[ref]

Reciprocal evolutionary change in traits of the sexes arising through opposed reproductive effects. Correlated morphologies alone need not prove historical reciprocal selection.