Period
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Period (from Greek περίοδος) or periodic may refer to:
Science
- Orbital period Copernicus devised a mathematical formula to calculate a planet's sidereal period from its synodic period, a concept in astronomy.
- Period (gene), a gene in Drosophila involved in regulating circadian rhythm
- Period (geology) The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth. The table of geologic time spans presented here agrees with the dates, a subdivision of geologic time
- Periodic function In mathematics, a periodic function is a function that repeats its values in regular intervals or periods. The most important examples are the trigonometric functions, which repeat over intervals of length 2π. Periodic functions are used throughout science to describe oscillations, waves, and other phenomena that exhibit periodicity and periodical, a function that repeats its values in regular intervals
- Periodic group In group theory, a periodic group or a torsion group is a group in which each element has finite order. All finite groups are periodic. The concept of a periodic group should not be confused with that of a cyclic group, although all finite cyclic groups are periodic in group theory
- Periodic table The periodic table of the chemical elements is a tabular display of the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869, who intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table, a chart which lists all currently known chemical elements
- Periodic acid Periodic acid, or iodic acid is an oxoacid of iodine having chemical formula HIO4 or H5IO6, an oxoacid of iodine
- Period (physics) Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency. The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency, the reciprocal of frequency
- Period of orbit In mathematics, in the study of dynamical systems, an orbit is a collection of points related by the evolution function of the dynamical system. The orbit is a subset of the phase space and the set of all orbits is a partition of the phase space, that is different orbits do not intersect in the phase space. Understanding the properties of orbits
- Period of time Periodization is the attempt to categorize or divide time into named blocks. The result is a descriptive abstraction that provides a useful handle on periods of time with relatively stable characteristics. However, determining the precise beginning and ending to any "period" is often a matter of debate
Language and literature
- Period A full stop or period (American English) (sometimes point or dot) is the punctuation mark commonly placed at the end of sentences, a punctuation mark indicating the end of a sentence or phrase
- Periodic sentence, a sentence that is not grammatically complete until its end
- The final book in Dennis Cooper's George Miles cycle Dennis Cooper is an American novelist, poet, critic, editor and performance artist of novels
History
- Pisano period
- Period piece In the performing arts, a period piece is a work set in a particular era. This informal term covers all countries, all periods and all genres. It may be as long and general as the medieval era or as limited as one decade—the Roaring Twenties, for example. Most commonly seen in film. A period piece movie is also referred to as a costume drama describes creative works set in a particular era.
Medical
- Menstruation, a phase of the menstrual cycle in which the uterine lining is shed
Mathematics
- The period of a periodic function In mathematics, a periodic function is a function that repeats its values in regular intervals or periods. The most important examples are the trigonometric functions, which repeat over intervals of length 2π. Periodic functions are used throughout science to describe oscillations, waves, and other phenomena that exhibit periodicity
- Ring of periods
Academics
- Period (school), a class period in schools
Other meanings
- Period (music) A period is a phrase consisting usually of an antecedent and consequent and totaling about 8 measures in length . Generally, the antecedent ends in a half cadence while the consequent ends in an authentic cadence. Frequently, the consequent strongly parallels the antecedent, even sharing most of the material save the final measures. In other cases,, a concept in musical composition
- Periodicity, the quality of occurring at regular intervals or periods
See also
- Periodization Periodization is the attempt to categorize or divide time into named blocks. The result is a descriptive abstraction that provides a useful handle on periods of time with relatively stable characteristics. However, determining the precise beginning and ending to any "period" is often a matter of debate
- Full stop (disambiguation)
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MarketWatch (press release) (A) Financial data is adjusted from amounts reported in prior periods for the change in accounting for direct costs related to the enrollment of new ... ITT Educational Services, Inc. Reports 2010 Second Quarter Results American Chronicle
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