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Bleeding within the substance of the spinal cord, distinguished from bleeding into surrounding spaces.

An acute phase of depressed reflex activity below severe spinal cord injury; it does not establish permanent destruction of all corresponding reflex circuits.

For a finite square matrix, powers tend to zero exactly when every eigenvalue has modulus less than one. In a complex Jordan normal form, the entries of a block power are sums of factors $\left(\genfrac{}{}{0ex}{}{k}{j}\right){\lambda }^{k-j}$, which tend to zero when $|\lambda |<1$; a zero-eigenvalue block becomes zero after finitely many powers. Conversely, an eigenvector gives $G^{k}v={\lambda }^{k}v$, so convergence to zero excludes $|\lambda |\ge 1$. This criterion underlies the convergence theorem for a stationary iterative method for a linear system.

A named software object instantiated once in the scope of its definition. A top-level Scala object can implement the singleton pattern. Nested object definitions can have different instances for different enclosing instances, so the relevant scope matters.

Equality according to the abstract content a software class exposes, rather than object identity. Distinct software objects can be equal by value. A Java equals(Object) override should define an equivalence relation and agree with its hash code. Equal content can have different internal subdivisions: occupied colour runs, for example, can be equal despite different brick boundaries.

A software design pattern organizing how software objects are created. A prototype pattern creates an object by asking an existing example to copy itself, letting a client choose a concrete configuration at runtime through an object interface.

A software design pattern organizing composition of classes and objects into larger structures. The decorator pattern wraps a component behind the same object interface, delegating existing work and adding one responsibility. Wrappers can be nested without declaring a new class for each combination.

A software design pattern concerned with allocating behavior and communication responsibilities among objects. Observer patterns notify dependents, while a command pattern represents a request as an object.

Separate an application's domain state and rules into a model, its presentation into a view, and interpretation of user actions into a controller. The controller requests model operations; the view renders coherent model state. A playlist model, for example, owns song order independently of whether a menu, button or keyboard action requests a move. The Observer pattern often carries model-change notifications to views, but model-view-controller defines responsibilities rather than requiring a particular notification mechanism. This supports separation of concerns and testing domain logic independently of a graphical interface.

With $a=-A>0$, a stable cycle grows from the origin. At $a_h\simeq 0.33144619$, symmetric saddle connections form a repelling heteroclinic cycle, while the stable inner cycle persists. Just above it an unstable outer cycle coexists with the stable one; they merge at $a_f\simeq 0.33147066$ in a saddle-node bifurcation of periodic orbits. These approximate values follow from the half-return equations $H_a(p)=p$, with $H_a^{\prime }(p)=1$ at the fold, and saddle-manifold shooting at the connection. A coarse parameter scan can miss the narrow coexistence interval. The saddle eigenvalue ratio is below one at the connection, proving that the loop is repelling and preventing identification of the stable cycle's disappearance with that connection.

Historical pharmaceutical preparation; its composition and clinical use must be identified by edition. ^[ref]

Historical name for modified smallpox, especially following vaccination; distinct from chickenpox.

Scan a nonempty linked list while remembering the predecessor of its least-valued node. A sentinel node supplies a predecessor even when the minimum is the first data node. Once the scan ends, bypass the selected node and detach its outgoing link. Using strict comparison retains the first occurrence among tied minima. Repeated extraction and tail-appending gives stable selection sort without replacing the data nodes or collapsing equal values.

The ratio of the useful load force to the applied effort force. For an ideal simple machine in slow motion, the ratio of effort displacement to load displacement gives the same number by conservation of work.

A body turning about a fulcrum. In static balance, effort and load supply equal and opposite torques: $E{d}_E=L{d}_L$, where the distances are perpendicular lever arms. Its ideal mechanical advantage is $L/E=d_E/d_L$. Measuring distances along the body instead of perpendicular to the force lines can give the wrong answer.

The sparingly soluble silver–iodide solid used in a classical iodide recognition test.

A water-soluble silver–fluoride compound. Its solubility explains why ordinary precipitation of insoluble silver halides is not an equivalent fluoride test.

A subset of a finite Cartesian product specifies which tuples of elements satisfy a relation. A first-order structure interprets a relation symbol with $n$ argument places as such a subset of the $n$-fold Cartesian product of its domain of a first-order structure. For two argument places this is a binary relation; for three, the set of triples satisfying $x+y=z$ is an example involving addition.

ZF without foundation consists of the axioms of Zermelo–Fraenkel set theory with the Axiom of foundation omitted. Ordinal-indexed transfinite recursion still defines the cumulative hierarchy. Its union is the well-founded part and need not include all ambient sets.