Four-velocity
In physics, in particular in special relativity and general relativity, a four-velocity is a four-vector in four-dimensional spacetime that represents the relativistic counterpart of velocity, which is a three-dimensional vector in space.
Physical events correspond to mathematical points in time and space, the set of all of them together forming a mathematical model of physical four-dimensional spacetime. The history of an object traces a curve in spacetime, called its world line. If the object is massive, so that its speed is less than the speed of light, the world line may be parametrized by the proper time of the object. The four-velocity is the rate of change of four-position with respect to the proper time along the curve. The velocity, in contrast, is the rate of change of the position in (three-dimensional) space of the object, as seen by an observer, with respect to the observer's time.
The value of the magnitude of an object's four-velocity, i. e. the quantity obtained by applying the metric tensor g to the four-velocity u, that is ||u||2 = u ⋅ u = gμνuνuμ, is always equal to ±c2, where c is the speed of light. Whether the plus or minus sign applies depends on the choice of metric signature. For an object at rest its four-velocity is parallel to the direction of the time coordinate with u0 = c. A four-velocity is thus the normalized future-directed timelike tangent vector to a world line, and is a contravariant vector. Though it is a vector, addition of two four-velocities does not yield a four-velocity: The space of four-velocities is not itself a vector space.
10 Speed (album)
10 Speed is the second studio album by the Canadian rock band Mystery Machine. It was released in Jan 23, 1996 on the Nettwerk America label. 10 Speed was a notable album for being one of the first forays into mixing media and music in compact discs.
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SPEED2000
SPEED2000 is a software package designed for electromagnetic simulation for the analysis and design of high-speed electronic systems. It combines an electromagnetic field solver with circuit and transmission line simulations which allows it to compute dynamic electromagnetic interactions within integrated circuits. SPEED2000 provides electrical analysis of integrated circuit (IC) packages and printed circuit boards (PCBs). It is developed and marketed by Sigrity, Inc.
History
The algorithims on which SPEED2000 is based were initially developed by Dr. Jiayuan Fang (then Associate Professor of Electrical Engineering at Binghamton University) and his students. The electromagnetic simulation algorithims that he developed were 1000 times faster previous methods.
Dr. Fang patented the algorithims (see below) and founded a company called Sigrity, Inc. to further develop the software. He eventually left Binghamton University to work on his software full-time. The rights to the initial patents are owned by Binghamton University and the royalties provide funding for current research efforts at the university.
Original (disambiguation)
Originality is the quality of novelty or newness in created works.
Original or The Originals may also refer to:
Books and publishing
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Sports
Films and television
Music
Bands
Runaway (2010 film)
Runaway is a 2010 American musical short film directed by Kanye West.
It serves as the music video for a compilation of songs from West's album, My Beautiful Dark Twisted Fantasy. It is inspired by other music-related films such as Purple Rain, Pink Floyd The Wall and Michael Jackson's Thriller and painters Pablo Picasso and Henri Matisse. Directors Federico Fellini and Stanley Kubrick as well as fashion designer Karl Lagerfeld are also direct inspirations. The film depicts a romantic relationship between a man and a half-woman, half-phoenix, and is set to music by Kanye West from his album My Beautiful Dark Twisted Fantasy (2010).
Synopsis
Runaway (TV serial)
Runaway is the story of a young boy who takes to the streets to get away from the torment he suffers at school and daily problems at home. Life at home is rife with daily doses of scoldings from his half-drunk mother, and his two younger brothers Dean and Jack pay him scant attention until noticing he is missing. On his journey, Sean meets a girl named Molly who takes him to a crumbling mill where her family lives. The series follows the police search for Sean, and how his disappearance affects his family.
Runaways was part of a short season on CBBC about children and homelessness, along with a 5-part documentary "Sofa Surfers". The program was first shown as three separated half-hour episodes in March 2009, and later as an 82-minute film.
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Runaway (Jim Carroll album)
Runaway is a 2000 EP album by author and punk musician Jim Carroll.
Track listing
Track 2 is a 1994 demo from Pools of Mercury
Tracks 3-5 recorded live at the Crocodile Cafe, Seattle on 17 November 1998
Personnel
References
Podcasts:
