Definitions

critical

critical point

In science, the set of conditions under which a liquid and its vapour become identical. The conditions are the critical temperature, the critical pressure, and the critical density. If a closed vessel is filled with a pure substance, partly liquid and partly vapour, and the average density equals the critical density, the critical conditions can be achieved. As the temperature is raised, the vapour pressure increases, and the gas phase becomes denser while the liquid expands and becomes less dense. At the critical point, the densities of liquid and vapour become equal, eliminating the boundary between the two.

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System of critical philosophy created by Immanuel Kant and the philosophies that have arisen from the study of his writings. Kantianism comprises diverse philosophies that share Kant's concern to explore the nature and limits of human knowledge in the hope of raising philosophy to the level of a science. Each submovement of Kantianism has tended to focus on its own selection and reading of Kant's many concerns. In the 1790s there emerged in Germany the so-called semi-Kantians, who altered features of Kant's system they viewed as inadequate, unclear, or even wrong; its members included Friedrich Schiller, Friedrich Bouterwek (1766–1828), and Jakob Friedrich Fries (1773–1843). The period from 1790 to 1835 was the age of the post-Kantian idealists (see idealism). A major revival of interest in Kantian philosophy began circa 1860. Seealso Johann Gottlieb Fichte; G.W.F. Hegel; Neo-Kantianism; Friedrich Wilhelm Joseph von Schelling.

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Minimum amount of a given fissionable material necessary to achieve a self-sustaining nuclear chain reaction under specified conditions. Critical mass depends on several factors, including the kind of fissionable material used, its concentration and purity, and the composition and geometry of the surrounding reaction system.

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Critical may denote:

More specifically:

Philosophy

Psychology and education

  • critical pedagogy - helping students achieve critical consciousness
  • critical psychology - critiquing mainstream psychology, often looking towards social change as a means of preventing and treating psychopathology
  • critical thinking - mental processes of discernment, analysis and evaluation

Biology and medicine

  • critical care - intensive care medicine
  • critical period - a time in the early stages of an organism's life during which it displays a heightened sensitivity to certain environmental stimuli, and develops in particular ways due to experiences at this time

Mathematics

Physics

  • critical angle - the angle of incidence above which total internal reflection occurs.
  • critical distance - in audio physics, the distance at which the sound pressure level of the direct and the reverberant sound fields are equal when dealing with a directional source.
  • critical mass - the smallest amount of fissile material needed for a sustained nuclear chain reaction.
  • critical point (thermodynamics) - conditions (temperature, pressure) at which the liquid state of matter ceases to exist
  • critical speed - the theoretical angular velocity which excites the natural frequency of a screw or gear.

Process control

  • Critical Control Point - a point, step or procedure at which controls can be applied and a food safety hazard can be prevented, eliminated or reduced to acceptable (critical) levels
  • critical hours - from sunrise to two hours after sunrise, and from two hours before sunset until sunset, local time
  • critical path method - project management algorithm
  • Critical Security Parameter - information that is either user or system defined and is used to operate a cryptography module in processing encryption functions
  • Critical Success Factor - an element which is necessary for an organization or project to achieve its mission.

Aviation

  • critical angle of attack - such that the airflow has separated from a substantial portion of the upper surface of the airfoil
  • critical area - designated area of an airport that all aircraft must remain clear of when another aircraft is inbound on an ILS approach
  • critical engine - the one whose failure would result in the most adverse effects on the aircraft's handling and performance
  • critical mach - the speed at which some of the airflow on a wing becomes supersonic.

Other

  • Critical (novel) - a medical thriller written by Dr. Robin Cook
  • critical focus - the portion of a photograph that is optically in focus
  • critical hit - in role-playing games, a successful attack that deals more damage than a normal hit
  • critical load - of a pollutant, minimum exposure threshold for known harmful effects
  • critical section - piece of code requiring single-thread to a shared device
  • Critical Software - company specializing in mission and business critical information systems.

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