By Clare M. O’Connor.

Online text: bio.libretexts.org/Bookshelves/Cell_and_Molecular_Biology/Investigations_in_Molecular_Cell_Biology_%28O%27Connor%29/12%3A_Yeast_Transformation/12.06%3A_Exercise_2_-_Replica_plating_and_complementation

Cited passages: O’Connor, Investigations in Molecular Cell Biology, §12.6, introductory paragraphs and steps 1–3: velveteen block, orientation marks and three replica media.

A class of introns with a conserved catalytic RNA core and a two-step RNA splicing mechanism initiated by external guanosine. Some can self-splice under suitable conditions, while others require protein assistance; the Tetrahymena example demonstrates that RNA can provide catalytic activity.

Online text: www.probabilitycourse.com/chapter6/6_2_1_union_bound_and_exten.php

Cited passages: Section 6.2.1, equation (6.2) and the closing paragraph on the expected number of occurring events.

Disabling selected asynchronous interrupt delivery, normally under privileged control. It does not necessarily disable processor exceptions, nonmaskable interrupts or activity on other processors.

// Target: computer-science.bigb

Hardware managing and routing interrupt requests to a CPU, with architecture-dependent masking and priority rules. The Linux kernel encapsulates its operations separately from generic flow handlers. ^[ref]

// Destination: computer-science.bigb

Code entered to handle an interrupt. It identifies and acknowledges relevant device state and arranges service, possibly deferring work. The Linux kernel's generic flow layer and device driver callback have distinct responsibilities. ^[ref]

In interrupt-driven input-output, a device signals an interrupt when attention is needed, letting the CPU avoid repeatedly checking an idle device. The interrupt handler determines what happened and arranges the required work; notification itself does not move the payload. DMA can supply that separate data-transfer mechanism.

For a toy comparison, let events occur at times $2,5,9$. Ideal interrupt notification happens at those same times, while polled input-output at $0,2,4,6,8,10,12$ detects them at $2,6,10$. The polling delays are $0,1,1$; ideal notification delays are all zero. Events are assumed to remain pending, with a simultaneous event visible to a poll. The chart is a model, not a measurement: it excludes interrupt delivery and dispatch latency, interrupt handler service time, and polling overhead. Its zero-delay row is not a real-hardware guarantee.

The useful idea is to spend attention when something changes. Sparse events can leave long stretches for useful CPU work instead of busy checks. At high event rates, repeated entry and service overhead can consume that saving. Batching notifications can reduce their frequency while delaying some events; switching to polled input-output during active periods is another option. No strategy is universally faster. ^[ref]

The Linux kernel's NAPI mechanism is a concrete combination: an interrupt normally schedules event processing, which polls for work with a receive budget. Further interrupts remain masked during that polling, and are enabled again when polling finishes. NAPI also supports busy polling; the exact processing context and configuration vary. This is a documented Linux kernel design, not a requirement on every operating system. ^[ref]

The volt is the SI unit of electric potential and electric potential difference: $1\mathrm{V}=1J/C$, one joule per coulomb. A positive electric charge of $2\mathrm{C}$ moved through a potential increase of $3\mathrm{V}$ gains $\Delta U=q\Delta \Phi =6\mathrm{J}$ of potential energy; the electric field does $-6\mathrm{J}$ of work. ^[ref].

The coulomb is the SI unit of electric charge. A constant electric current of $1\mathrm{A}$ transports $1\mathrm{C}$ in a time of $1\mathrm{s}$; a constant current of $2\mathrm{A}$ for $3\mathrm{s}$ transports $6\mathrm{C}$. The prefix in $1\mathrm{nC}=10^{-9}\mathrm{C}$ explains the much smaller charge scale used in the worked Coulomb's law example. ^[ref]

The joule is the SI unit of energy, work, and heat. One newton of force acting along one metre of displacement does one joule of work. The relation $1\mathrm{J}=1\mathrm{N}\mathrm{m}$ makes mechanical and electrical transfers comparable in the same energy unit. ^[ref]

The pascal is the SI unit of pressure:For a uniform normal force of $10\mathrm{N}$ over area $0.02{\mathrm{m}}^2$, the pressure is $500\mathrm{Pa}$. The unit expresses a force per area, rather than the total force alone. ^[ref].

The newton is the SI unit of force:This combines the units of mass and acceleration in Newton's second law. ^[ref].

The mole is the SI base unit of amount of substance. One mole contains exactly $6.02214076\times 10^{23}$ specified entities, as fixed by the Avogadro constant. It counts entities rather than a fixed mass or volume. ^[ref]

Online text: farside.ph.utexas.edu/teaching/355/Surveyhtml/node83.html

Cited passages: Richard Fitzpatrick, Ideal Conductors, equations 2.124–2.126: zero field and constant potential in metal; Richard Fitzpatrick, Ideal Conductors, equations 2.127 and the following uniqueness argument: a charge-free enclosed cavity; Richard Fitzpatrick, Ideal Conductors: charge-free cavities and uniqueness.

Online text: textbooks.math.gatech.edu/ila/rank-thm.html

Cited passages: Margalit and Rabinoff, Interactive Linear Algebra, §2.9, Rank Theorem: column count equals rank plus nullity.

Online text: textbooks.math.gatech.edu/ila/solution-sets.html

Cited passages: Margalit and Rabinoff, Interactive Linear Algebra, §2.4.2, Key Observation and Remark: translate the homogeneous solution set by any particular solution.

A communication object on which software threads send or receive IPC messages. In seL4, an IPC endpoint is an operating-system kernel object with waiting senders or receivers; access requires a suitable security capability. ^[ref]

Here light intensity means the time-averaged energy flux per perpendicular area for light. It is the propagation-direction component of the averaged Poynting vector. For plane electromagnetic waves in the same medium it is proportional to squared electric field wave amplitude, giving the projection-squared factor in Malus's law.