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Early computer-generated models of planetary formation predicted the existence of terrestrial planets around both Alpha Centauri A and B, but most recent numerical investigations have shown that the gravitational pull of the companion star renders the accretion of planets difficult. Despite these difficulties, given th... | Alpha Centauri | Wikipedia | 459 | 1979 | https://en.wikipedia.org/wiki/Alpha%20Centauri | Physical sciences | Notable stars | null |
With the goal of finding evidence of such planets, both Proxima Centauri and were among the listed "Tier-1" target stars for NASA's Space Interferometry Mission (S.I.M.). Detecting planets as small as three Earth-masses or smaller within two AU of a "Tier-1" target would have been possible with this new instrument. Th... | Alpha Centauri | Wikipedia | 490 | 1979 | https://en.wikipedia.org/wiki/Alpha%20Centauri | Physical sciences | Notable stars | null |
A planet around either or B would see the other star as a very bright secondary. For example, an Earth-like planet at from (with a revolution period of 1.34 years) would get Sun-like illumination from its primary, and would appear 5.7–8.6 magnitudes dimmer (−21.0 to −18.2), 190–2,700 times dimmer than but still 15... | Alpha Centauri | Wikipedia | 462 | 1979 | https://en.wikipedia.org/wiki/Alpha%20Centauri | Physical sciences | Notable stars | null |
{| class="wikitable sortable mw-collapsible"
|+ Alpha Centauri AB historical distance estimates
|-
! rowspan="2" | Source
! rowspan="2" |Year
! rowspan="2" |Subject!! rowspan="2" | Parallax (mas) !! colspan="3" | Distance !! rowspan="2" | | Alpha Centauri | Wikipedia | 91 | 1979 | https://en.wikipedia.org/wiki/Alpha%20Centauri | Physical sciences | Notable stars | null |
Amiga is a family of personal computers produced by Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-bit or 16/32-bit processors, 256 KB or more of RAM, mouse-based GUIs, and significantly improved graph... | Amiga | Wikipedia | 409 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Overview
The Amiga 1000, based on the Motorola 68000 microprocessor, was released in July 1985. Production problems kept it from becoming widely available until early 1986. While early advertisements cast the computer as an all-purpose business machine, especially when outfitted with the Sidecar IBM PC compatibility a... | Amiga | Wikipedia | 443 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
With the 8-bit line's launch in 1979, the team once again started looking at a next generation chipset. Nolan Bushnell had sold the company to Warner Communications in 1978, and the new management was much more interested in the existing lines than development of new products that might cut into their sales. Miner want... | Amiga | Wikipedia | 487 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Commodore
During 1983, Atari lost over a week due to the combined effects of the crash and the ongoing price war in the home computer market. By the end of the year, Warner was desperate to sell the company. In January 1984, Jack Tramiel resigned from Commodore due to internal battles over the future direction of the... | Amiga | Wikipedia | 384 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Launch
The first model was announced in 1985 as simply "The Amiga from Commodore", later to be retroactively dubbed the Amiga 1000. They were first offered for sale in August, but by October only 50 had been built, all of which were used by Commodore. Machines only began to arrive in quantity in mid-November, meaning t... | Amiga | Wikipedia | 415 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
The Amiga line sold an estimated 4,910,000 machines over its lifetime. The machines were most popular in the UK and Germany, with about 1.5 million sold in each country, and sales in the high hundreds of thousands in other European nations. The machine was less popular in North America, where an estimated 700,000 were ... | Amiga | Wikipedia | 510 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
The Amiga has a custom chipset consisting of several coprocessors which handle audio, video, and direct memory access independently of the central processing unit (CPU). This architecture gave the Amiga a performance edge over its competitors, particularly for graphics-intensive applications and games.
The architectur... | Amiga | Wikipedia | 442 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Custom chipset
The custom chipset at the core of the Amiga design appeared in three distinct generations, with a large degree of backward-compatibility. The Original Chip Set (OCS) appeared with the launch of the A1000 in 1985. OCS was eventually followed by the modestly improved Enhanced Chip Set (ECS) in 1990 and fi... | Amiga | Wikipedia | 452 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
ReTargetable Graphics is an API for device drivers mainly used by 3rd party graphics hardware to interface with AmigaOS via a set of libraries. The software libraries may include software tools to adjust resolution, screen colors, pointers and screenmodes. The standard Intuition interface is limited to display depths o... | Amiga | Wikipedia | 485 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Kickstart is the firmware upon which AmigaOS is bootstrapped. Its purpose is to initialize the Amiga hardware and core components of AmigaOS and then attempt to boot from a bootable volume, such as a floppy disk or hard disk drive. Most models (excluding the Amiga 1000) come equipped with Kickstart on an embedded ROM-c... | Amiga | Wikipedia | 473 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Like IBM-compatible computers, the mouse has two buttons, but in AmigaOS, pressing and holding the right button replaces the system status line at the top of the screen with a Maclike menu bar. As with Apple's Mac OS prior to Mac OS 8, menu options are selected by releasing the button over that option, not by left clic... | Amiga | Wikipedia | 444 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Phase5 designed the PowerUP boards (Blizzard PPC and CyberStorm PPC) featuring both a 68k (a 68040 or 68060) and a PowerPC (603 or 604) CPU, which are able to run the two CPUs at the same time and share the system memory. The PowerPC CPU on PowerUP boards is usually used as a coprocessor for heavy computations; a power... | Amiga | Wikipedia | 473 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Expansion boards were made by Richmond Sound Design that allow their show control and sound design software to communicate with their custom hardware frames either by ribbon cable or fiber optic cable for long distances, allowing the Amiga to control up to eight million digitally controlled external audio, lighting, au... | Amiga | Wikipedia | 454 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Networking
Amiga has three networking interface APIs:
AS225: the official Commodore TCP/IP stack API with hard-coded drivers in revision 1 (AS225r1) for the A2065 Ethernet and the A2060 Arcnet interfaces. In revision 2, (AS225r2) the SANA-II interface was used.
SANA-II: a standardized API for hardware of network int... | Amiga | Wikipedia | 490 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
The CDTV, launched in 1991, was a CD-ROM-based game console, Computer and multimedia appliance based on the Amiga A500 with the same v1.3 Kickstart ROM, several years before CD-ROM drives were common. The cost of CDTV media production and the CD-ROM drives at the time discouraged potential buyers and the system never a... | Amiga | Wikipedia | 493 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
AmigaOS 4.0 had been available only in developer pre-releases for numerous years until it was officially released in December 2006. Due to the nature of some provisions of the contract between Amiga Inc. and Hyperion Entertainment (the Belgian company that is developing the OS), the commercial AmigaOS 4 had been availa... | Amiga | Wikipedia | 470 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
In 1998, Index Information released the Access, an Amiga-clone similar to the Amiga 1200, but on a motherboard that could fit into a standard -inch drive bay. It features either a 68020 or 68030 CPU, with a AGA chipset, and runs AmigaOS 3.1.
In 1998, former Amiga employees (John Smith, Peter Kittel, Dave Haynie and An... | Amiga | Wikipedia | 487 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
In 2006, two new Amiga clones were announced, both using FPGA based hardware synthesis to replace the Amiga OCS custom chipset. The first, the Minimig, is a personal project of Dutch engineer Dennis van Weeren. Referred to as "new Amiga hardware", the original model was built on a Xilinx Spartan-3 development board, bu... | Amiga | Wikipedia | 486 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
The multi-tasking kernel is called Exec. It acts as a scheduler for tasks running on the system, providing pre-emptive multitasking with prioritised round-robin scheduling. It enabled true pre-emptive multitasking in as little as 256 KB of free memory.
AmigaOS does not implement memory protection; the 68000 CPU does n... | Amiga | Wikipedia | 367 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Influence on other operating systems
AmigaOS directly or indirectly inspired the development of various operating systems. MorphOS and AROS clearly inherit heavily from the structure of AmigaOS as explained directly in articles regarding these two operating systems. AmigaOS also influenced BeOS, which featured a centr... | Amiga | Wikipedia | 501 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Until the late 1990s the Amiga remained a popular platform for non-commercial software, often developed by enthusiasts, and much of which was freely redistributable. An on-line archive, Aminet, was created in 1991 and until the late-1990s was the largest public archive of software, art and documents for any platform.
... | Amiga | Wikipedia | 307 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Genesi sold PowerPC based hardware under the Pegasos brand running AmigaOS and MorphOS;
Eyetech sold PowerPC based hardware under the AmigaOne brand from 2002 to 2005 running AmigaOS 4;
Amiga Kit distributes and sells PowerPC based hardware under the AmigaOne brand from 2010 to present day running AmigaOS 4;
ACube S... | Amiga | Wikipedia | 485 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Uses
The Amiga series of computers found a place in early computer graphic design and television presentation. Season 1 and part of season 2 of the television series Babylon 5 were rendered in LightWave 3D on Amigas. Other television series using Amigas for special effects included SeaQuest DSV and Max Headroom.
In a... | Amiga | Wikipedia | 75 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Andy Warhol was an early user of the Amiga and appeared at the launch, where he made a computer artwork of Debbie Harry. Warhol used the Amiga to create a new style of art made with computers, and was the author of a multimedia opera called You Are the One, which consists of an animated sequence featuring images of act... | Amiga | Wikipedia | 512 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Bob Casale, keyboardist and guitarist of the new wave band Devo, used Amiga computer graphics on the album cover to Devo's album Total Devo.
Most of Pokémon Gold and Silver's music was created on an Amiga computer, converted to MIDI, and then reconverted to the game's music format.
American professional skateboarder ... | Amiga | Wikipedia | 262 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Special purpose applications
Amigas were used in various NASA laboratories to keep track of low orbiting satellites until 2004. Amigas were used at Kennedy Space Center to run strip-chart recorders, to format and display data, and control stations of platforms for Delta rocket launches.
Palomar Observatory used Amiga... | Amiga | Wikipedia | 225 | 1980 | https://en.wikipedia.org/wiki/Amiga | Technology | Specific hardware | null |
Algebraic geometry is a branch of mathematics which uses abstract algebraic techniques, mainly from commutative algebra, to solve geometrical problems. Classically, it studies zeros of multivariate polynomials; the modern approach generalizes this in a few different aspects.
The fundamental objects of study in algebra... | Algebraic geometry | Wikipedia | 459 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Much of the development of the mainstream of algebraic geometry in the 20th century occurred within an abstract algebraic framework, with increasing emphasis being placed on "intrinsic" properties of algebraic varieties not dependent on any particular way of embedding the variety in an ambient coordinate space; this pa... | Algebraic geometry | Wikipedia | 465 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
A function f : An → A1 is said to be polynomial (or regular) if it can be written as a polynomial, that is, if there is a polynomial p in k[x1,...,xn] such that f(M) = p(t1,...,tn) for every point M with coordinates (t1,...,tn) in An. The property of a function to be polynomial (or regular) does not depend on the choic... | Algebraic geometry | Wikipedia | 418 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
The answer to the first question is provided by introducing the Zariski topology, a topology on An whose closed sets are the algebraic sets, and which directly reflects the algebraic structure of k[An]. Then U = V(I(U)) if and only if U is an algebraic set or equivalently a Zariski-closed set. The answer to the second ... | Algebraic geometry | Wikipedia | 508 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Since regular functions on V come from regular functions on An, there is a relationship between the coordinate rings. Specifically, if a regular function on V is the restriction of two functions f and g in k[An], then f − g is a polynomial function which is null on V and thus belongs to I(V). Thus k[V] may be identifie... | Algebraic geometry | Wikipedia | 460 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
If V is an affine variety, its coordinate ring is an integral domain and has thus a field of fractions which is denoted k(V) and called the field of the rational functions on V or, shortly, the function field of V. Its elements are the restrictions to V of the rational functions over the affine space containing V. The ... | Algebraic geometry | Wikipedia | 442 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
To see how this might come about, consider the variety . If we draw it, we get a parabola. As x goes to positive infinity, the slope of the line from the origin to the point (x, x2) also goes to positive infinity. As x goes to negative infinity, the slope of the same line goes to negative infinity.
Compare this to the... | Algebraic geometry | Wikipedia | 413 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Nowadays, the projective space Pn of dimension n is usually defined as the set of the lines passing through a point, considered as the origin, in the affine space of dimension , or equivalently to the set of the vector lines in a vector space of dimension . When a coordinate system has been chosen in the space of dimen... | Algebraic geometry | Wikipedia | 511 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
One open problem in real algebraic geometry is the following part of Hilbert's sixteenth problem: Decide which respective positions are possible for the ovals of a nonsingular plane curve of degree 8.
Computational algebraic geometry
One may date the origin of computational algebraic geometry to meeting EUROSAM'79 (I... | Algebraic geometry | Wikipedia | 314 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Given an ideal I defining an algebraic set V:
V is empty (over an algebraically closed extension of the basis field), if and only if the Gröbner basis for any monomial ordering is reduced to {1}.
By means of the Hilbert series one may compute the dimension and the degree of V from any Gröbner basis of I for a monomia... | Algebraic geometry | Wikipedia | 485 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
This theorem concerns the formulas of the first-order logic whose atomic formulas are polynomial equalities or inequalities between polynomials with real coefficients. These formulas are thus the formulas which may be constructed from the atomic formulas by the logical operators and (∧), or (∨), not (¬), for all (∀) an... | Algebraic geometry | Wikipedia | 409 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Among these algorithms which solve a sub problem of the problems solved by Gröbner bases, one may cite testing if an affine variety is empty and solving nonhomogeneous polynomial systems which have a finite number of solutions. Such algorithms are rarely implemented because, on most entries Faugère's F4 and F5 algorith... | Algebraic geometry | Wikipedia | 371 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Most remarkably, in the early 1960s, algebraic varieties were subsumed into Alexander Grothendieck's concept of a scheme. Their local objects are affine schemes or prime spectra which are locally ringed spaces which form a category which is antiequivalent to the category of commutative unital rings, extending the duali... | Algebraic geometry | Wikipedia | 436 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Algebraic stacks can be further generalized and for many practical questions like deformation theory and intersection theory, this is often the most natural approach. One can extend the Grothendieck site of affine schemes to a higher categorical site of derived affine schemes, by replacing the commutative rings with an... | Algebraic geometry | Wikipedia | 309 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Before the 16th century
Some of the roots of algebraic geometry date back to the work of the Hellenistic Greeks from the 5th century BC. The Delian problem, for instance, was to construct a length x so that the cube of side x contained the same volume as the rectangular box a2b for given sides a and b. Menaechmus () co... | Algebraic geometry | Wikipedia | 342 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Such techniques of applying geometrical constructions to algebraic problems were also adopted by a number of Renaissance mathematicians such as Gerolamo Cardano and Niccolò Fontana "Tartaglia" on their studies of the cubic equation. The geometrical approach to construction problems, rather than the algebraic one, was f... | Algebraic geometry | Wikipedia | 314 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
19th and early 20th century
It took the simultaneous 19th century developments of non-Euclidean geometry and Abelian integrals in order to bring the old algebraic ideas back into the geometrical fold. The first of these new developments was seized up by Edmond Laguerre and Arthur Cayley, who attempted to ascertain the ... | Algebraic geometry | Wikipedia | 456 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
In the 1950s and 1960s, Jean-Pierre Serre and Alexander Grothendieck recast the foundations making use of sheaf theory. Later, from about 1960, and largely led by Grothendieck, the idea of schemes was worked out, in conjunction with a very refined apparatus of homological techniques. After a decade of rapid development... | Algebraic geometry | Wikipedia | 282 | 1997 | https://en.wikipedia.org/wiki/Algebraic%20geometry | Mathematics | Algebra | null |
Avionics (a portmanteau of aviation and electronics) are the electronic systems used on aircraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searc... | Avionics | Wikipedia | 475 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
The civilian market has also seen a growth in cost of avionics. Flight control systems (fly-by-wire) and new navigation needs brought on by tighter airspaces, have pushed up development costs. The major change has been the recent boom in consumer flying. As more people begin to use planes as their primary method of tra... | Avionics | Wikipedia | 320 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
Aircraft avionics
The cockpit or, in larger aircraft, under the cockpit of an aircraft or in a movable nosecone, is a typical location for avionic bay equipment, including control, monitoring, communication, navigation, weather, and anti-collision systems. The majority of aircraft power their avionics using 14- or 28‑v... | Avionics | Wikipedia | 311 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
Installation Process
The installation of avionics requires a combination of technical expertise, precision, and adherence to stringent regulatory standards. The process typically involves:
Planning and Design: Before installation, the avionics shop works closely with the aircraft owner to determine the required syste... | Avionics | Wikipedia | 504 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
Communications connect the flight deck to the ground and the flight deck to the passengers. On‑board communications are provided by public-address systems and aircraft intercoms.
The VHF aviation communication system works on the airband of 118.000 MHz to 136.975 MHz. Each channel is spaced from the adjacent ones by 8... | Avionics | Wikipedia | 446 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
Aircraft have means of automatically controlling flight. Autopilot was first invented by Lawrence Sperry during World War I to fly bomber planes steady enough to hit accurate targets from 25,000 feet. When it was first adopted by the U.S. military, a Honeywell engineer sat in the back seat with bolt cutters to disconne... | Avionics | Wikipedia | 489 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
To help avoid controlled flight into terrain (CFIT), aircraft use systems such as ground-proximity warning systems (GPWS), which use radar altimeters as a key element. One of the major weaknesses of GPWS is the lack of "look-ahead" information, because it only provides altitude above terrain "look-down". In order to ov... | Avionics | Wikipedia | 468 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
Mission or tactical avionics
Military aircraft have been designed either to deliver a weapon or to be the eyes and ears of other weapon systems. The vast array of sensors available to the military is used for whatever tactical means required. As with aircraft management, the bigger sensor platforms (like the E‑3D, JSTA... | Avionics | Wikipedia | 476 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
Aircraft networks
The avionics systems in military, commercial and advanced models of civilian aircraft are interconnected using an avionics databus. Common avionics databus protocols, with their primary application, include:
Aircraft Data Network (ADN): Ethernet derivative for Commercial Aircraft
Avionics Full-Duple... | Avionics | Wikipedia | 223 | 2039 | https://en.wikipedia.org/wiki/Avionics | Technology | Aircraft components | null |
In computer science, an array is a data structure consisting of a collection of elements (values or variables), of same memory size, each identified by at least one array index or key. An array is stored such that the position of each element can be computed from its index tuple by a mathematical formula. The simplest ... | Array (data structure) | Wikipedia | 481 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
The term "array" may also refer to an array data type, a kind of data type provided by most high-level programming languages that consists of a collection of values or variables that can be selected by one or more indices computed at run-time. Array types are often implemented by array structures; however, in some lang... | Array (data structure) | Wikipedia | 481 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
One or more large arrays are sometimes used to emulate in-program dynamic memory allocation, particularly memory pool allocation. Historically, this has sometimes been the only way to allocate "dynamic memory" portably.
Arrays can be used to determine partial or complete control flow in programs, as a compact alternat... | Array (data structure) | Wikipedia | 478 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
In standard arrays, each index is restricted to a certain range of consecutive integers (or consecutive values of some enumerated type), and the address of an element is computed by a "linear" formula on the indices.
One-dimensional arrays
A one-dimensional array (or single dimension array) is a type of linear array.... | Array (data structure) | Wikipedia | 451 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
This means that array a has 2 rows and 3 columns, and the array is of integer type. Here we can store 6 elements they will be stored linearly but starting from first row linear then continuing with second row. The above array will be stored as a11, a12, a13, a21, a22, a23.
This formula requires only k multiplications ... | Array (data structure) | Wikipedia | 498 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
In the row-major order layout (adopted by C for statically declared arrays), the elements in each row are stored in consecutive positions and all of the elements of a row have a lower address than any of the elements of a consecutive row:
{| class="wikitable"
|-
| 1 || 2 || 3 || 4 || 5 || 6 || 7 || 8 || 9
|}
In colum... | Array (data structure) | Wikipedia | 490 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
Non-linear formulas
More complicated (non-linear) formulas are occasionally used. For a compact two-dimensional triangular array, for instance, the addressing formula is a polynomial of degree 2.
Efficiency
Both store and select take (deterministic worst case) constant time. Arrays take linear (O(n)) space in the numb... | Array (data structure) | Wikipedia | 488 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
Associative arrays provide a mechanism for array-like functionality without huge storage overheads when the index values are sparse. For example, an array that contains values only at indexes 1 and 2 billion may benefit from using such a structure. Specialized associative arrays with integer keys include Patricia tries... | Array (data structure) | Wikipedia | 438 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
This should not be confused with the dimension of the set of all matrices with a given domain, that is, the number of elements in the array. For example, an array with 5 rows and 4 columns is two-dimensional, but such matrices form a 20-dimensional space. Similarly, a three-dimensional vector can be represented by a on... | Array (data structure) | Wikipedia | 76 | 2052 | https://en.wikipedia.org/wiki/Array%20%28data%20structure%29 | Mathematics | Data structures and types | null |
Aeronautics is the science or art involved with the study, design, and manufacturing of air flight-capable machines, and the techniques of operating aircraft and rockets within the atmosphere.
While the term originally referred solely to operating the aircraft, it has since been expanded to include technology, busines... | Aeronautics | Wikipedia | 360 | 2082 | https://en.wikipedia.org/wiki/Aeronautics | Technology | Concepts of aviation | null |
In the late fifteenth century, Leonardo da Vinci followed up his study of birds with designs for some of the earliest flying machines, including the flapping-wing ornithopter and the rotating-wing helicopter. Although his designs were rational, they were not based on particularly good science. Many of his designs, such... | Aeronautics | Wikipedia | 482 | 2082 | https://en.wikipedia.org/wiki/Aeronautics | Technology | Concepts of aviation | null |
Meanwhile, the discovery of hydrogen led Joseph Black in to propose its use as a lifting gas, though practical demonstration awaited a gas-tight balloon material. On hearing of the Montgolfier Brothers' invitation, the French Academy member Jacques Charles offered a similar demonstration of a hydrogen balloon. Charles... | Aeronautics | Wikipedia | 438 | 2082 | https://en.wikipedia.org/wiki/Aeronautics | Technology | Concepts of aviation | null |
Cayley and the foundation of modern aeronautics
Sir George Cayley (1773–1857) is widely acknowledged as the founder of modern aeronautics. He was first called the "father of the aeroplane" in 1846 and Henson called him the "father of aerial navigation." He was the first true scientific aerial investigator to publish hi... | Aeronautics | Wikipedia | 439 | 2082 | https://en.wikipedia.org/wiki/Aeronautics | Technology | Concepts of aviation | null |
His work lead to him developing the concept of the modern wing. His flight attempts in Berlin in the year 1891 are seen as the beginning of human flight and the "Lilienthal Normalsegelapparat" is considered to be the first air plane in series production, making the Maschinenfabrik Otto Lilienthal in Berlin the first ai... | Aeronautics | Wikipedia | 476 | 2082 | https://en.wikipedia.org/wiki/Aeronautics | Technology | Concepts of aviation | null |
Rockets are used for fireworks, weaponry, ejection seats, launch vehicles for artificial satellites, human spaceflight and exploration of other planets. While comparatively inefficient for low speed use, they are very lightweight and powerful, capable of generating large accelerations and of attaining extremely high sp... | Aeronautics | Wikipedia | 120 | 2082 | https://en.wikipedia.org/wiki/Aeronautics | Technology | Concepts of aviation | null |
Aphasia, also known as dysphasia, is an impairment in a person’s ability to comprehend or formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aphasia due to stroke is estimated to be 0.1–0.4% in developed countries. Aphasia ca... | Aphasia | Wikipedia | 346 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
With aphasia, one or more modes of communication in the brain have been damaged and are therefore functioning incorrectly. Aphasia is not caused by damage to the brain resulting in motor or sensory deficits, thus producing abnormal speech — that is, aphasia is not related to the mechanics of speech, but rather the indi... | Aphasia | Wikipedia | 510 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Related behaviors
Given the previously stated signs and symptoms, the following behaviors are often seen in people with aphasia as a result of attempted compensation for incurred speech and language deficits:
Self-repairs: Further disruptions in fluent speech as a result of mis-attempts to repair erred speech producti... | Aphasia | Wikipedia | 473 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
In addition to deficits in short-term memory, working memory, and attention, people with aphasia can also demonstrate deficits in executive function. For instance, people with aphasia may demonstrate deficits in initiation, planning, self-monitoring, and cognitive flexibility. Other studies have found that people with ... | Aphasia | Wikipedia | 506 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Substantial damage to tissue anywhere within the region shown in blue (on the figure in the infobox above) can potentially result in aphasia. Aphasia can also sometimes be caused by damage to subcortical structures deep within the left hemisphere, including the thalamus, the internal and external capsules, and the caud... | Aphasia | Wikipedia | 508 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
There are limitations to the use of fMRI in aphasic patients particularly. Because a high percentage of aphasic patients develop it because of stroke there can be infarct present which is the total loss of blood flow. This can be due to the thinning of blood vessels or the complete blockage of it. This is important in ... | Aphasia | Wikipedia | 464 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Associated conditions
In a study on the features associated with different disease trajectories in Alzheimer's disease (AD)-related primary progressive aphasia (PPA), it was found that metabolic patterns via PET SPM analysis can help predict progression of total loss of speech and functional autonomy in AD and PPA pati... | Aphasia | Wikipedia | 422 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Classification
Aphasia is best thought of as a collection of different disorders, rather than a single problem. Each individual with aphasia will present with their own particular combination of language strengths and weaknesses. Consequently, it is a major challenge just to document the various difficulties that can ... | Aphasia | Wikipedia | 329 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Individuals with receptive aphasia (Wernicke's aphasia), also referred to as fluent aphasia, may speak in long sentences that have no meaning, add unnecessary words, and even create new "words" (neologisms). For example, someone with receptive aphasia may say, "delicious taco", meaning "The dog needs to go out so I wil... | Aphasia | Wikipedia | 220 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Individuals with expressive aphasia (Broca's aphasia) frequently speak short, meaningful phrases that are produced with great effort. It is thus characterized as a nonfluent aphasia. Affected people often omit small words such as "is", "and", and "the". For example, a person with expressive aphasia may say, "walk dog",... | Aphasia | Wikipedia | 486 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Individuals with transcortical sensory aphasia, in principle the most general and potentially among the most complex forms of aphasia, may have similar deficits as in receptive aphasia, but their repetition ability may remain intact.
Global aphasia is considered a severe impairment in many language aspects since it im... | Aphasia | Wikipedia | 446 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Transcortical aphasias include transcortical motor aphasia, transcortical sensory aphasia, and mixed transcortical aphasia. People with transcortical motor aphasia typically have intact comprehension and awareness of their errors, but poor word finding and speech production. People with transcortical sensory and mixed ... | Aphasia | Wikipedia | 120 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Classical-localizationist approaches
Localizationist approaches aim to classify the aphasias according to their major presenting characteristics and the regions of the brain that most probably gave rise to them. Inspired by the early work of nineteenth-century neurologists Paul Broca and Carl Wernicke, these approach... | Aphasia | Wikipedia | 414 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Recent classification schemes adopting this approach, such as the Boston-Neoclassical Model, also group these classical aphasia subtypes into two larger classes: the nonfluent aphasias (which encompasses Broca's aphasia and transcortical motor aphasia) and the fluent aphasias (which encompasses Wernicke's aphasia, cond... | Aphasia | Wikipedia | 337 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Instead of categorizing every individual into a specific subtype, cognitive neuropsychological approaches aim to identify the key language skills or "modules" that are not functioning properly in each individual. A person could potentially have difficulty with just one module, or with a number of modules. This type of ... | Aphasia | Wikipedia | 459 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Progressive Jargon Aphasia is a fluent or receptive aphasia in which the person's speech is incomprehensible, but appears to make sense to them. Speech is fluent and effortless with intact syntax and grammar, but the person has problems with the selection of nouns. Either they will replace the desired word with another... | Aphasia | Wikipedia | 193 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Deaf aphasia
There have been many instances showing that there is a form of aphasia among deaf individuals. Sign languages are, after all, forms of language that have been shown to use the same areas of the brain as verbal forms of language. Mirror neurons become activated when an animal is acting in a particular way ... | Aphasia | Wikipedia | 341 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Severity
The severity of the type of aphasia varies depending on the size of the stroke. However, there is much variance between how often one type of severity occurs in certain types of aphasia. For instance, any type of aphasia can range from mild to profound. Regardless of the severity of aphasia, people can make i... | Aphasia | Wikipedia | 358 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
To prevent aphasia due to traumatic injury, one should take precautionary measures when engaging in dangerous activities such as:
Wearing a helmet when operating a bicycle, motor cycle, ATV, or any other moving vehicle that could potentially be involved in an accident
Wearing a seatbelt when driving or riding in a ca... | Aphasia | Wikipedia | 488 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
There is no one treatment proven to be effective for all types of aphasias. The reason that there is no universal treatment for aphasia is because of the nature of the disorder and the various ways it is presented. Aphasia is rarely exhibited identically, implying that treatment needs to be catered specifically to the ... | Aphasia | Wikipedia | 499 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Semantic feature analysis (SFA) — a type of aphasia treatment that targets word-finding deficits — is based on the theory that neural connections can be strengthened by using related words and phrases that are similar to the target word, to eventually activate the target word in the brain. SFA can be implemented in mul... | Aphasia | Wikipedia | 455 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
When addressing Wernicke's aphasia, according to Bakheit et al. (2007), the lack of awareness of the language impairments, a common characteristic of Wernicke's aphasia, may affect the rate and extent of therapy outcomes. Robey (1998) determined that at least 2 hours of treatment per week is recommended for making sign... | Aphasia | Wikipedia | 506 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Individualized service delivery
Intensity of treatment should be individualized based on the recency of stroke, therapy goals, and other specific characteristics such as age, size of lesion, overall health status, and motivation. Each individual reacts differently to treatment intensity and is able to tolerate treatmen... | Aphasia | Wikipedia | 383 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Prevalence
Aphasia affects about two million people in the U.S. and 250,000 people in Great Britain. Nearly 180,000 people acquire the disorder every year in the U.S., 170,000 due to stroke. Any person of any age can develop aphasia, given that it is often caused by a traumatic injury. However, people who are middle a... | Aphasia | Wikipedia | 501 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
Further research
Research is currently being done using functional magnetic resonance imaging (fMRI) to witness the difference in how language is processed in normal brains vs aphasic brains. This will help researchers to understand exactly what the brain must go through in order to recover from Traumatic Brain Injury ... | Aphasia | Wikipedia | 252 | 2088 | https://en.wikipedia.org/wiki/Aphasia | Biology and health sciences | Disabilities | Health |
The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at the aortic bifurcation into two smaller arteries (the common iliac arteries). The aorta distrib... | Aorta | Wikipedia | 439 | 2089 | https://en.wikipedia.org/wiki/Aorta | Biology and health sciences | Circulatory system | Biology |
At the root of the ascending aorta, the lumen has small pockets between the cusps of the aortic valve and the wall of the aorta, which are called the aortic sinuses or the sinuses of Valsalva. The left aortic sinus contains the origin of the left coronary artery and the right aortic sinus likewise gives rise to the ri... | Aorta | Wikipedia | 432 | 2089 | https://en.wikipedia.org/wiki/Aorta | Biology and health sciences | Circulatory system | Biology |
The thoracic aorta gives rise to the intercostal and subcostal arteries, as well as to the superior and inferior left bronchial arteries and variable branches to the esophagus, mediastinum, and pericardium. Its lowest pair of branches are the superior phrenic arteries, which supply the diaphragm, and the subcostal arte... | Aorta | Wikipedia | 491 | 2089 | https://en.wikipedia.org/wiki/Aorta | Biology and health sciences | Circulatory system | Biology |
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