The spherical-particle polarization-contrast factor $\tilde{K}=({\widetilde{ϵ}}_p-{\widetilde{ϵ}}_m)/({\widetilde{ϵ}}_p+2{\widetilde{ϵ}}_m)$. Its real part controls ordinary time-averaged dielectrophoresis in the quasistatic dipole approximation.

A Dicer-like protein that processes canonical precursors into 24-nucleotide siRNAs.

The products contribute to canonical RNA-directed DNA methylation in plants. Processing converts a longer double-stranded precursor into guide-sized fragments, linking RNA production to later sequence-directed chromatin regulation. ^[ref]

The product $\chi N$ of the Flory interaction parameter and degree of polymerization, using compatible reference-segment conventions. It compares unlike-contact avoidance with chain entropy; solvent dilution need not change the chemical chain length.

The fraction of dry polymer volume assigned to one block, $f_A=V_A/(V_A+V_B)$. Selective solvent swelling changes an effective domain-volume ratio without changing this dry chemical composition.

A domain structure can persist because chain relaxation is too slow to reach the thermodynamic equilibrium morphology. A glassy block, rapid solvent loss or strong segregation can impede defect correction. Controlled thermal or solvent annealing and time-dependent structural measurements distinguish arrested patterns from equilibrated phase stability.

The neutral molecule Be-two. Its simplest filled sigma-two-s/bonding and antibonding description gives zero bond order, but mixing of accessible two-p configurations and electron correlation produce a weak covalent bond. Resolved vibrational levels establish a bound ground-state potential.^[ref]

A very weakly bound van der Waals molecule, observed in cold helium expansions. The absence of an ordinary covalent bond in the elementary molecular orbital model must not be confused with absence of every possible bound dimer.^[ref]

The neutral molecule Li-two. In the elementary valence molecular orbital description, its two valence electrons occupy the bonding sigma-two-s orbital, giving bond order one and a closed-shell ground state.

A heteronuclear three-valence-electron diatomic. A simple bonding/antibonding two-orbital description predicts bond order one-half and one unpaired electron. More electronegative beryllium carries the negative end of the bond dipole.

With one atom at the origin and the second FCC sublattice displaced by $(1/4,1/4,1/4)$, the vertical mirrors normal to directions perpendicular to $[001]$ have traces $x-y=n/2$ or $x+y=n/2$ in fractional coordinates. Checking the atomic heights distinguishes a genuine mirror from a misleading planar projection.

The point $(1/8,1/8,1/8)$ is an inversion centre when an atom is at the origin. Inversion sends $\mathbf{r}$ to $(1/4,1/4,1/4)-\mathbf{r}$ and exchanges the identical FCC sublattices. The individual atomic sites are not inversion centres.

Nearest neighbors are separated by $a\sqrt{3}/4$, so touching spheres have radius $a\sqrt{3}/8$. Eight atoms in a conventional cell occupy fraction $\pi \sqrt{3}/16\simeq 0.3401$. The underlying FCC Bravais lattice does not make this two-atom network close packed.

Preservation or replication by calcium phosphate minerals, sometimes retaining soft-tissue detail when precipitation occurs before its destruction.

Reduction of sediment volume during burial that can flatten, distort or fracture enclosed remains.

precipitation or replacement by minerals during burial alteration. Early mineral formation can retain fine biological detail, while later alteration can destroy or obscure it.

Change in the crystal organization of fossil material during alteration, potentially obscuring original histological or chemical information.

The deuteron has a dominant ${}^3{S}_1$ component and a smaller ${}^3{D}_1$ component coupled by the nuclear tensor force. The electric quadrupole moment rules out a purely isotropic S wave spatial state. A D-state probability depends on the chosen nuclear Hamiltonian and current approximation; it is not an independently model-free observable.

If source class $i$ has prior fraction $p_i$ and detection efficiency ${\eta }_i$, its fraction among detected events is proportional to $p_i{\eta }_i$. Bayes' theorem normalizes these products. Class-dependent losses therefore bias the detected composition even when the incident fractions are known exactly.

single-stranded DNA is DNA present as one polymer strand rather than an ordinary paired duplex. It can form secondary structures or associate with proteins; single-stranded does not imply an entirely straight, unstructured chain.

double-stranded DNA contains two associated DNA strands, ordinarily paired through base pairing. Their separation and re-pairing underlies DNA strand exchange.