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Period
Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept in grammar and literary style. * Period, a descriptor for a historical or period drama * Period, a timeframe in which a particular style of antique furniture or some other work of art was produced, such as the "Edwardian period" * '' Period (Another American Lie)'', a 1987 album by B.A.L.L. * ''Period'' (Kesha album), an upcoming album by Kesha * ''Period'' (mixtape), a 2018 mixtape by City Girls * ''Period'', the final book in Dennis Cooper's George Miles cycle of novels * '' Periods.'', a comedy film series Mathematics * In a repeating decimal, the length of the repetend * Period of a function, length or duration after which a function repeats itself * Period (algebraic geometry), numbers that can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (geology)
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardised international units of geological time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period Of A Function
A periodic function, also called a periodic waveform (or simply periodic wave), is a function that repeats its values at regular intervals or periods. The repeatable part of the function or waveform is called a ''cycle''. For example, the trigonometric functions, which repeat at intervals of 2\pi radians, are periodic functions. Periodic functions are used throughout science to describe oscillations, waves, and other phenomena that exhibit periodicity. Any function that is not periodic is called ''aperiodic''. Definition A function is said to be periodic if, for some nonzero constant , it is the case that :f(x+P) = f(x) for all values of in the domain. A nonzero constant for which this is the case is called a period of the function. If there exists a least positive constant with this property, it is called the fundamental period (also primitive period, basic period, or prime period.) Often, "the" period of a function is used to mean its fundamental period. A function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Period
The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit. For celestial objects in general, the orbital period is determined by a 360° revolution of one body around its primary, ''e.g.'' Earth around the Sun. Periods in astronomy are expressed in units of time, usually hours, days, or years. Its reciprocal is the orbital frequency, a kind of revolution frequency, in units of hertz. Small body orbiting a central body According to Kepler's Third Law, the orbital period ''T'' of two point masses orbiting each other in a circular or elliptic orbit is: :T = 2\pi\sqrt where: * ''a'' is the orbit's semi-major axis * ''G'' is the gravitationa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repeating Decimal
A repeating decimal or recurring decimal is a decimal representation of a number whose digits are eventually periodic (that is, after some place, the same sequence of digits is repeated forever); if this sequence consists only of zeros (that is if there is only a finite number of nonzero digits), the decimal is said to be ''terminating'', and is not considered as repeating. It can be shown that a number is rational if and only if its decimal representation is repeating or terminating. For example, the decimal representation of becomes periodic just after the decimal point, repeating the single digit "3" forever, i.e. 0.333.... A more complicated example is , whose decimal becomes periodic at the ''second'' digit following the decimal point and then repeats the sequence "144" forever, i.e. 5.8144144144.... Another example of this is , which becomes periodic after the decimal point, repeating the 13-digit pattern "1886792452830" forever, i.e. 11.18867924528301886792452830.... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (algebraic Geometry)
In mathematics, specifically algebraic geometry, a period or algebraic period is a complex number that can be expressed as an integral of an algebraic function over an algebraic domain. The periods are a class of numbers which includes, alongside the algebraic numbers, many well known mathematical constants such as the number π. Sums and products of periods remain periods, such that the periods \mathcal P form a ring. Maxim Kontsevich and Don Zagier gave a survey of periods and introduced some conjectures about them. Periods play an important role in the theory of differential equations and transcendental numbers as well as in open problems of modern arithmetical algebraic geometry. They also appear when computing the integrals that arise from Feynman diagrams, and there has been intensive work trying to understand the connections. Definition A number \alpha is a period if it can be expressed as an integral of the form :\alpha = \int_Q(x_1,\ldots,x_n)\ \mathrmx_1\ldots\mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (school)
A school period is a block of time allocated for lessons, classes in schools. They typically last between 30 and 60 minutes, with around 3-10 periods per school day. However, especially in higher education, there can be many more. Educators determine the number and length of these periods, and may even regulate how each period will be used. One common example of this practice is to designate at least one compulsory period a day for physical education. Free period One special example of a period is the free period. These are typically shorter than regular periods and allow students to participate in non-class activities. A free period (also called a spare, unstructured, or leisure period) is generally found in most high schools and colleges. Students may utilize a free period for various purposes: * Walk around the campus freely until the next period. Some high schools permit students to leave the campus and go home, visit shops or areas nearby that are outside the school grounds. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (periodic Table)
A period on the periodic table is a row of chemical elements. All Chemical element, elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, elements in the same group (periodic table), group (column) have similar chemical property, chemical and physical property, physical properties, reflecting the periodic law. For example, the halogens lie in the second-to-last group (Halogen, group 17) and share similar properties, such as high reactivity and the tendency to gain one electron to arrive at a noble-gas electronic configuration. , a total of 118 elements have been discovered and confirmed. Modern quantum mechanics explains these periodic trends in properties in terms of electron shells. As atomic number increases, shells fill with electrons in approximately the order shown in the ordering rule diagram. The filling of each shell corresponds to a row in the table. In t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menstruation
Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and Mucous membrane, mucosal tissue from the endometrium, inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hormones. Menstruation is triggered by falling progesterone levels, and is a sign that pregnancy has not occurred. Women use feminine hygiene products to maintain hygiene during menses. The first period, a point in time known as menarche, usually begins during puberty, between the ages of 11 and 13. However, menstruation starting as young as 8 years would still be considered normal. The average age of the first period is generally later in the developing world, and earlier in the developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women; in adults, the range is between 21 and 35 days with the average often cited as 28 days. In the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (music)
In music theory, the term period refers to forms of repetition and contrast between adjacent small-scale Musical form, formal structures such as phrases. In twentieth-century music scholarship, the term is usually used similarly to the definition in the ''Oxford Companion to Music'': "a period consists of two phrases, antecedent and consequent, each of which begins with the same basic motif (music), motif." Earlier and later usages vary somewhat, but usually refer to notions of symmetry, difference, and an open section followed by a closure. The concept of a musical period originates in comparisons between music structure and rhetoric at least as early as the 16th century. Western art music In Western art music or Classical music, a period is a group of phrase (music), phrases consisting usually of at least one antecedent phrase and one consequent phrase totaling about 8 bar (music), bars in length (though this varies depending on meter and tempo). Generally, the antecedent end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (punctuation)
The full stop (Commonwealth English), period (North American English), or full point is a punctuation mark used for several purposes, most often to mark the end of a declarative sentence (as distinguished from a question or exclamation). A full stop is frequently used at the end of word abbreviations—in British English, British usage, primarily truncations like ''Rev.'', but not after Contraction (grammar), contractions like ''Revd''; in American English, it is used in both cases. It may be placed after an initial letter used to abbreviate a word. It is often placed after each individual letter in acronyms and initialisms (e.g., "U.S."). However, the use of full stops after letters in an initialism or acronym is declining, and many of these without punctuation have become accepted norms (e.g., "UK" and "NATO"). When used in a series (typically of three, an ellipsis) the mark is also used to indicate omitted words. In the English-speaking world, a punctuation mark identical t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Full Stop (other)
The full stop ( Commonwealth English), period (North American English), or full point is a punctuation mark used for several purposes, most often to mark the end of a declarative sentence (as distinguished from a question or exclamation). A full stop is frequently used at the end of word abbreviations—in British usage, primarily truncations like ''Rev.'', but not after contractions like '' Revd''; in American English, it is used in both cases. It may be placed after an initial letter used to abbreviate a word. It is often placed after each individual letter in acronyms and initialisms (e.g., "U.S."). However, the use of full stops after letters in an initialism or acronym is declining, and many of these without punctuation have become accepted norms (e.g., "UK" and "NATO"). When used in a series (typically of three, an ellipsis) the mark is also used to indicate omitted words. In the English-speaking world, a punctuation mark identical to the full stop is used as the decim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotation Period
In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the object takes to complete a full rotation around its axis relative to the background stars ( inertial space). The other type of commonly used "rotation period" is the object's '' synodic rotation period'' (or ''solar day''), which may differ, by a fraction of a rotation or more than one rotation, to accommodate the portion of the object's orbital period around a star or another body during one day. Measuring rotation For solid objects, such as rocky planets and asteroids, the rotation period is a single value. For gaseous or fluid bodies, such as stars and giant planets, the period of rotation varies from the object's equator to its pole due to a phenomenon called differential rotation. Typically, the stated rotation period for a giant pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
