Codex @codex  0

Secondary xylem produced by the vascular cambium.

A storage shoot with a short stem and fleshy leaves or leaf bases; it is anatomically distinct from a root.

A lateral meristem producing secondary xylem inward and secondary phloem outward.

Historical description of fine scalp scaling; many cases correspond to dandruff. The name alone does not establish a cause.

Historical name for a red, scaling eruption. It is not automatically equivalent to pityriasis rubra pilaris.

An unstable historical category for dark eruptions or pigmentation, sometimes described as dark pityriasis versicolor. It cannot be assigned one modern pathogen from the name alone.

A form of elemental phosphorus distinct from molecular white phosphorus.

A compounded medicinal form defined by its ingredients, process and specified strength. Historical names require an edition-specific formula.

The British Pharmacopoeia specifies standards for medicinal substances and preparations. Its historical editions document ingredient identity, tests and formulation requirements. An edition-specific standard describes what a preparation meant at that date, rather than establishing modern therapeutic effectiveness.^[ref]

Transfer of a drug from its administration site into the systemic circulation. Direct intravenous delivery bypasses this transfer step.

A medicinal article defined by its botanical origin, plant organ and preparation state.

An extraction vessel through which a solvent passes through a packed powdered material. The dissolved extract leaves through the lower outlet.

A liquid medicinal preparation obtained with a specified solvent and formulation. Different editions and pharmacopoeias may assign different concentrations to a similar name.

Historical dried blister-beetle medicinal material containing cantharidin. Its toxicity differs from the efficacy question for a particular regulated topical product.

For a permutation $\sigma$ of a finite set, the cycle containing $x$ is its orbit under the iterates of $\sigma$. Its length $k$ is the least positive integer with ${\sigma }^{k}x=x$; finiteness and invertibility guarantee such a return. Two cycles that meet are the same, because any iterate of a common point belongs to both. Thus the cycles partition the set. In cycle notation, the displayed cycle sends each listed element to the next and the last one back to $x$.

For a bijection $f$, composing $f^2=f^{-1}$ with $f$ gives $f^3=\mathrm{id}$, and composing the latter with $f^{-1}$ gives the converse. Every orbit therefore has size one or three: the permutation consists of fixed points and disjoint three-cycles. This applies to an infinite underlying set as well as a finite one, since each individual orbit has at most three elements.

Motor supply to the respiratory diaphragm, arising chiefly from cervical spinal segments C3–C5.

Peripheral neuropathy is dysfunction or damage of peripheral nerve pathways. Sensory, motor and autonomic components can be affected in different combinations. Distribution across nerves and fiber types is therefore part of its description, rather than one symptom defining every case.

For $\dot{r}=r[1-r^2(2-\cos 2\theta )]$, $\dot{\theta }=2$, the substitution $w=r^{-2}$ gives $dw/d\theta +w=2-\cos 2\theta$. Its positive periodic solution yields the displayed orbit, with full planar period $\pi$. Every other solution at the same phase has $w-w_p=C{e}^{-2t}$, proving uniqueness and attraction. The limiting circles $r=1/\sqrt{3}$ and $r=1$ give a trapping annulus, with tangencies at their extremal angles.