Sequencing depth describes the amount of sequence observation obtained, but its exact convention depends on the assay. For a genome, nominal mean depth can be approximated by total sequenced bases divided by target length; in RNA sequencing, depth often means the number of reads generated. Larger depth improves sampling of rare material but does not fix systematic bias or substitute for biological replication. ^[ref]

A regulatory mechanism in which a chemical modification changes RNA secondary structure and thereby exposes or occludes a functional element. Modification dependence of binding alone does not distinguish this mechanism from direct chemical recognition.^[ref]

A structured RNA recognition element bound by iron regulatory proteins. In suitable 5′ contexts it controls biological translation, whereas a 3′ stability-control context can regulate RNA decay. It is not an autonomous iron-sensing riboswitch.

Bringing separated RNA segments into proximity while an intervening segment forms a loop. Multivalent RNA-binding proteins can stabilize this geometry, with consequences for accessibility and splice-site use.

A fission-yeast small-RNA-guided chromatin silencing complex including Argonaute and a methyl-mark-binding component.^[ref]

A short RNA that guides sequence-specific silencing through an Argonaute protein; different pathways use different lengths and targets.

An Argonaute-containing effector complex guided by small RNA. Target binding can produce cleavage, translational repression or RNA destabilization depending on the guide, effector and target.

Generation of small regulatory RNAs without Dicer cleavage. Piwi-interacting RNA production and nematode RNA-dependent RNA polymerase-generated secondary RNAs are important examples.

An ideal resistor, inductor and capacitor connected across the same voltage have admittance $Y=1/R+i(\omega C-1/(\omega L))$ in the $e^{i\omega t}$ convention. At ${\omega }_0=1/\sqrt{LC}$ the reactive branch currents cancel, giving minimum source current $V_0/R$ and maximum impedance $R$. This differs from a lossy series coil placed across a capacitor.

An intrinsic two-dimensional metric locally written $d{s}^2=d{r}^2+f(r{)}^{2}d{\varphi }^2$ with positive $f$. Rotation of the angular coordinate is an isometry. Such a metric need not have a global realization as a surface of revolution in three-dimensional Euclidean space.

For $p>0$, integral comparison for $x^{-1-p}$ bounds its convergent positive series by $1/p\le {\sum }_{n\ge 1}{n}^{-1-p}\le 1+1/p$. Multiplication by $p$ gives $1\le p\zeta (1+p)\le 1+p$, so the squeeze theorem proves the displayed real-axis limit. This establishes the leading $1/p$ divergence by real integration alone. The convergence of the series at each fixed positive $p$ follows from bounded increasing partial sums via the monotone convergence theorem for sequences.

A ribonuclease H system capable of recognizing a single ribonucleotide embedded in DNA and initiating its removal. This substrate is distinct from a longer RNA–DNA hybrid.

Concentric cylinders impose shear while torque and rotation measure a material's response. The displayed calibration holds for Newtonian laminar flow, inner-cylinder rotation and a stationary outer cylinder. In a narrow gap, the rate is approximately $\Omega R_i/(R_o-R_i)$ and inner-wall stress is $\mathcal{T}/(2\pi L{R}_i^2)$. End effects, wall slip and inertial secondary flow require control.

The retarded Green function for $d^2/d{t}^2+1$ is $G_R(t)=\Theta (t)\sin t$, with Fourier transform $[1-(\omega +i{0}^{+}{)}^2{]}^{-1}$ in the $e^{-i\omega t}$ convention. Both poles lie below the real axis. Convolution with a force gives the solution with no incoming homogeneous oscillation. A source that is nonzero at negative times can have a nonzero response before a chosen zero of time without violating causality.

Resonance donation is electron-pair delocalization from a substituent into an adjacent conjugated system. Drawing electron-pair arrows into the system gives contributing charge-separated structures; their stabilization can change reaction rates and preferred sites.

Control separating competence to initiate from actual origin firing so that genomic regions are not repeatedly copied within one S phase. Details include kinase activity and organism-specific licensing inhibitors.