An earthquake occurring in the region affected by an earlier event during its subsequent relaxation and stress redistribution. A spatial aftershock pattern can help identify a fault, but not every aftershock must lie on the main rupture plane.

The relative displacement across a fault surface. Its vector and the fault normal determine an ideal double-couple seismic moment; a finite rupture can have spatially and temporally variable slip.

A fault plane is an idealized planar surface across which rock has slipped. A curved fault can be described by local fault planes. Its orientation is specified by fault strike and fault dip, and the slip direction within it by fault rake.

The hypocenter is the point where an earthquake rupture starts, rather than necessarily the centroid of its eventual slip distribution.

An earthquake centroid is an effective average location of seismic moment release. It differs from the hypocenter, where rupture starts, and can depend on the source representation and observations. An associated centroid time similarly averages release rather than marking its first instant.

An elastic rebound model describes slow loading of a locked fault, storage of elastic strain energy, and sudden slip with stress reduction when the fault fails. The surrounding rock partly relaxes while retaining a permanent displacement across the fault. It does not by itself predict the failure time, rupture extent or frictional dynamics, and continuous creep need not follow this ideal cycle.

antiperiplanar conformation elimination in a cyclohexane chair with axial leaving group and axial beta hydrogen.

Alternating an active mode with a lower-power mode to reduce average demand. Sleep current and transition overhead prevent average power from falling indefinitely in direct proportion to active time.

A dressed state of an atom and its driving field. Within the rotating-wave approximation, the paired configurations $|e,n⟩$ and $|g,n+1⟩$ mix. A classical-drive rotating-frame Hamiltonian $H=\hslash (-\Delta {\sigma }_z+\Omega {\sigma }_x)/2$ has eigenvalues $\pm \hslash \sqrt{{\Delta }^2+{\Omega }^2}/2$. At resonance its eigenvectors are equal-weight combinations of the two bare configurations. Radiative transitions between neighboring manifolds explain the Mollow triplet.

Differentiating $E_k\simeq \sqrt{{\hslash }^{3}q\alpha k/2}/m$ gives the displayed group velocity when $q\alpha k>0$. Its sign is the sign of $q\alpha$, equivalently of k on that branch. Writing only a positive square root of $q\alpha /k$ would lose this sign. Exactly, the Hellmann–Feynman theorem gives $v_y=⟨\hslash k-q\alpha x^2/2⟩/m$. Evaluating this small drift from a localized wavefunction requires enough anharmonic accuracy: a leading centred Gaussian alone need not reproduce it.

An effective coupling that separates the two-electron singlet state and triplet states by energy $J$. For a symmetric two-site Hubbard model with weak tunnelling $t_c$ and charging cost $U$, $J\simeq 4t_c^2/U$. Gate-controlled detuning and tunnelling change the interaction; the simple expression does not hold at arbitrary detuning or strong charge hybridization.

A single electron shared by two dots has a left/right charge basis. In that basis, a two-level model is $H=(\epsilon {\sigma }_z+2t_c{\sigma }_x)/2$, where detuning sets the energy imbalance and tunnelling mixes the states. Electrical control and charge sensing are direct, but electric-potential fluctuations also couple strongly to the encoded information.

With equal rod lengths $\ell$ and absolute downward-vertical angles $\theta ,\varphi$, the endpoint separation is $s^2=2{\ell }^2[1+\cos (\theta -\varphi )]$. A zero-rest-length spring between the fixed support and the final mass contributes $-\kappa {\ell }^2[1+\cos (\theta -\varphi )]$ to the Lagrangian. It favours bending away from maximum extension and can reduce the gravitational bending stiffness.

A sequence that exposes and transfers one sparse pattern, then applies fresh resist and transfers a second aligned pattern. Their union defines a denser final mask or etched layer. Pattern transfer between exposures prevents simple addition of optical dose from replacing two independently resolved exposures.

A lepton-number-violating nuclear transformation emitting two electrons without neutrinos. A signal appears near the nuclear Q value in summed electron energy, after recoil and detector response are accounted for. Its interpretation requires the decay mechanism and nuclear matrix elements.

The principal E. coli chromosomal replicative DNA polymerase, operating with a sliding clamp and associated replication factors.