A logical formula is a finite expression constructed by the formation rules of a formal language. Propositional formulas combine propositional variables by logical connectives. First-order formulas additionally contain terms, atomic relations and quantifiers. A logical formula is a syntactic object; its truth is determined only after specifying a suitable interpretation and values for its free variables.

Financial volatility quantifies variability of asset returns. In the Black-Scholes model, $\sigma$ is the coefficient of the Brownian increment in the stock return $d{S}_t/S_t=\mu dt+\sigma d{W}_t$, so its instantaneous log-return variance rate is ${\sigma }^2$. For deterministic time-varying volatility, the variance over an interval is the integral of that squared coefficient.

A dividend is a payment to the holder of a financial asset in addition to changes in its quoted price. Under a continuous dividend yield $\delta$, one stock unit produces cash $\delta S_{t}dt$, so its total gains are $d{S}_t+\delta S_{t}dt$. A self-financing portfolio must include this cash in its budget equation.

The Eulerian time derivative measures a continuum field's rate of change at a fixed Eulerian coordinate. For a velocity field $\mathbf{u}$, the material derivative instead follows a fluid element and satisfies $Df/Dt={\partial }_{t}f+\mathbf{u}\cdot \nabla f$. A nonuniform steady flow has zero Eulerian time derivative of velocity but can have nonzero material acceleration.

The dimensionless ratio of two specified masses.

A grain (unit) is a unit of mass equal to exactly $64.79891\mathrm{mg}$, or $0.00006479891\mathrm{kg}$. Thus a recorded mass of ten grains converts to $647.9891\mathrm{mg}$. The abbreviation is $\mathrm{gr}$; it must be distinguished from $\mathrm{g}$, the symbol for a gram.^[ref]

A grain (unit) measures mass, whereas a minim measures volume. Converting a volume to a mass additionally requires the material's density, so these units cannot be substituted for one another. The exact conversion is useful when interpreting an older measurement without treating the mass of an individual seed as a physical standard.

A nutrient deficiency occurs when availability of a required nutrient is insufficient for normal function. Low intake, impaired absorption and altered requirements can reach that outcome through different routes. Vitamin C deficiency illustrates why a specific missing factor can cause dysfunction despite an otherwise substantial food intake.

A valve limiting backward movement of lymph.

A mesenteric lymph node is a lymph node associated with drainage from intestinal regions through the mesentery. Its position links intestinal material and immune surveillance. Sampling this node therefore probes a particular drainage territory rather than the whole immune system equally.

A region of an activated secondary lymphoid follicle in which B cells proliferate and undergo selection.

The paracortex is a region of a lymph node between the outer cortical follicles and deeper medullary areas. It is associated with T-cell-rich immune interactions and specialized routes of cell entry. Location, cell composition and function distinguish it from a germinal center.

Lipid-rich intestinal lymph.

For the Liénard system $\dot{x}=z-F(x)$, $\dot{z}=-g(x)$ with $F=x^3/3-2x$, $g=x^3-x$, and $V^{\prime }=g$, the displayed function is coercive up to a constant. Differentiation gives $\dot{W}=-gF-z^2+Fz+xg\le -z^2/2-5x^6/18+8x^4/3-x^2$. Its derivative is negative outside a compact set, providing bounded forward dynamics even though the original oscillator has negative damping near the origin. The coordinate $z=y+F(x)$ exposes this restoring and damping balance.

A historical local anaesthesia method described by Benjamin Ward Richardson in 1866: an atomizer distributes diethyl ether, whose rapid vaporization cools the surface. The physical cooling mechanism and the author's historical account of nerve signalling should be distinguished.^[ref]

Inflammation of the liver. Viruses are one possible cause, but the word does not make every case infectious or identify one particular virus.

Impaired flow or secretion of bile; it can arise within the liver or from extrahepatic obstruction.

For a predicate $p$, normalize the state to the first remaining passing element with seek = dropWhile (not . p). Stop on an empty state, otherwise emit its head and continue from seek (tail state). The invariant is that every nonempty state starts with a passing element. An initial seek establishes it; removing the emitted head and seeking again preserves it. Each rejected run is traversed once, giving linear time in the examined input prefix under constant-cost predicate tests.

Instrument maker associated with the Fortin barometer.