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Rho 0
Rho (uppercase Ρ, lowercase ρ or ; el, ρο or el, ρω, label=none) is the 17th letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician letter res . Its uppercase form uses the same glyph, Ρ, as the distinct Latin letter P; the two letters have different Unicode encodings. Uses Greek Rho is classed as a liquid consonant (together with Lambda and sometimes the nasals Mu and Nu), which has important implications for morphology. In both Ancient and Modern Greek, it represents a alveolar trill , alveolar tap , or alveolar approximant . In polytonic orthography, a rho at the beginning of a word is written with a rough breathing, equivalent to ''h'' ( ''rh''), and a double rho within a word is written with a smooth breathing over the first rho and a rough breathing over the second ( ''rrh''). That apparently reflected an aspirated or voiceless pronunciation in Ancient Greek, which led to the var ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Density
The density of air or atmospheric density, denoted '' ρ'', is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in atmospheric pressure, temperature and humidity. At 101.325 kPa (abs) and 20 °C (68 °F), air has a density of approximately , according to the International Standard Atmosphere (ISA). At 101.325kPa (abs) and , air has a density of approximately , which is about that of water, according to the International Standard Atmosphere (ISA). Pure liquid water is . Air density is a property used in many branches of science, engineering, and industry, including aeronautics;Olson, Wayne M. (2000) AFFTC-TIH-99-01, Aircraft Performance FlightICAO, Manual of the ICAO Standard Atmosphere (extended to 80 kilometres (262 500 feet)), Doc 7488-CD, Third Edition, 1993, .Grigorie, T.L., Dinca, L., Corcau J-I. and Grigorie, O. (2010) Aircrafts' Altitude Measurement Using Pressure Information:Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alveolar Tap
Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * Mammary alveolus, a milk sac in the mammary glands * Alveolar gland * Dental alveolus, also known as "tooth socket", a socket in the jaw that holds the roots of teeth ** Alveolar ridge, the jaw structure that contains the dental alveoli ** Alveolar canals ** Alveolar process * Arteries: ** Superior alveolar artery (other) *** Anterior superior alveolar arteries *** Posterior superior alveolar artery ** Inferior alveolar artery * Nerves: ** Anterior superior alveolar nerve ** Middle superior alveolar nerve ** Inferior alveolar nerve Uses in botany, microbiology and related disciplines * Surface cavities or pits, such as on the stem of Myrmecodia species * Pits on honeycombed surfaces such as receptacles of many angiosperms * Pits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematically, density is defined as mass divided by volume: : \rho = \frac where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure. To simplify comparisons of density across different systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Sciences
Physical science is a branch of natural science that studies non-living systems, in contrast to life science. It in turn has many branches, each referred to as a "physical science", together called the "physical sciences". Definition Physical science can be described as all of the following: * A branch of science (a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe)."... modern science is a discovery as well as an invention. It was a discovery that nature generally acts regularly enough to be described by laws and even by mathematics; and required invention to devise the techniques, abstractions, apparatus, and organization for exhibiting the regularities and securing their law-like descriptions." —p.vii, J. L. Heilbron, (2003, editor-in-chief). ''The Oxford Companion to the History of Modern Science''. New York: Oxford University Press. . ** A branch of natural science – natu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics with the major subdisciplines of number theory, algebra, geometry, and analysis, respectively. There is no general consensus among mathematicians about a common definition for their academic discipline. Most mathematical activity involves the discovery of properties of abstract objects and the use of pure reason to prove them. These objects consist of either abstractions from nature orin modern mathematicsentities that are stipulated to have certain properties, called axioms. A ''proof'' consists of a succession of applications of deductive rules to already established results. These results include previously proved theorems, axioms, andin case of abstraction from naturesome basic properties that are considered true starting points of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for scientific reasoning is tens of thousands of years old. The earliest written records in the history of science come from Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE. Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes. After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages, but was preserved in the Muslim world during the Islamic Golden Age and later by the efforts of Byzantine Greek scholars who brought Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Er (Cyrillic)
Er (Р р; italics: ) is a letter of the Cyrillic script. It commonly represents the alveolar trill , like the "rolled" sound in the Scottish pronunciation of in "curd". History The Cyrillic letter er was derived from the Greek letter Rho (Ρ ρ). The name of er in the Early Cyrillic alphabet was (''rĭci''), meaning "speak". In the Cyrillic numeral system, er had a value of 100. Form The Cyrillic letter Er (Р р) looks similar to the Greek letter Rho (Ρ ρ), and the same as the Latin letter P ( П in Cyrillic). Usage As used in the alphabets of various languages, р represents the following sounds: * alveolar trill , like the "rolled" sound in the Scottish pronunciation of in "curd" * palatalized alveolar trill The voiced alveolar trill is a type of consonantal sound used in some spoken languages. The symbol in the International Phonetic Alphabet that represents dental, alveolar, and postalveolar trills is , and the equivalent X-SAMPA symb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voiceless
In linguistics, voicelessness is the property of sounds being pronounced without the larynx vibrating. Phonologically, it is a type of phonation, which contrasts with other states of the larynx, but some object that the word phonation implies voicing and that voicelessness is the lack of phonation. The International Phonetic Alphabet has distinct letters for many voiceless and modally voiced pairs of consonants (the obstruents), such as . Also, there are diacritics for voicelessness, and , which is used for letters with a descender. Diacritics are typically used with letters for prototypically voiced sounds, such as vowels and sonorant consonants: . In Russian use of the IPA, the voicing diacritic may be turned for voicelessness, e.g. . Voiceless vowels and other sonorants Sonorants are sounds such as vowels and nasals that are voiced in most of the world's languages. However, in some languages sonorants may be voiceless, usually allophonically. For example, the Japanese w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspirated Consonant
In phonetics, aspiration is the strong burst of breath that accompanies either the release or, in the case of preaspiration, the closure of some obstruents. In English, aspirated consonants are allophones in complementary distribution with their unaspirated counterparts, but in some other languages, notably most South Asian languages (including Indian) and East Asian languages, the difference is contrastive. In dialects with aspiration, to feel or see the difference between aspirated and unaspirated sounds, one can put a hand or a lit candle in front of one's mouth, and say ''spin'' and then ''pin'' . One should either feel a puff of air or see a flicker of the candle flame with ''pin'' that one does not get with ''spin''. Transcription In the International Phonetic Alphabet (IPA), aspirated consonants are written using the symbols for voiceless consonants followed by the aspiration modifier letter , a superscript form of the symbol for the voiceless glottal fricative . Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smooth Breathing
The smooth breathing ( grc, ψιλὸν πνεῦμα, psilòn pneûma; ell, ψιλή ''psilí''; la, spīritus lēnis) is a diacritical mark used in polytonic orthography. In Ancient Greek, it marks the absence of the voiceless glottal fricative from the beginning of a word. Some authorities have interpreted it as representing a glottal stop, but a final vowel at the end of a word is regularly elided (removed) when the following word starts with a vowel and elision would not happen if the second word began with a glottal stop (or any other form of stop consonant). In his ''Vox Graeca'', W.S. Allen accordingly regards the glottal stop interpretation as "highly improbable". The smooth breathing mark ( ) is written as on top of one initial vowel, on top of the second vowel of a diphthong or to the left of a capital and also, in certain editions, on the first of a pair of rhos. It did not occur on an initial upsilon, which always has rough breathing (thus the early name ''hy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemination
In phonetics and phonology, gemination (), or consonant lengthening (from Latin 'doubling', itself from ''gemini'' 'twins'), is an articulation of a consonant for a longer period of time than that of a singleton consonant. It is distinct from stress. Gemination is represented in many writing systems by a doubled letter and is often perceived as a doubling of the consonant.William Ham, ''Phonetic and Phonological Aspects of Geminate Timing'', p. 1-18 Some phonological theories use "doubling" as a synonym for gemination, others describe two distinct phenomena. Consonant length is a distinctive feature in certain languages, such as Arabic, Berber, Danish, Estonian, Hindi, Hungarian, Italian, Japanese, Kannada, Punjabi, Polish and Turkish. Other languages, such as English, do not have word-internal phonemic consonant geminates. Consonant gemination and vowel length are independent in languages like Arabic, Japanese, Finnish and Estonian; however, in languages like Italian, No ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
