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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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Ashkenazi Jewish Intelligence
Whether Ashkenazi Jews have higher average intelligence than other ethnic groups, and if so, why, has been an occasional subject of scientific controversy. Studies have generally found Ashkenazi Jews to have an average intelligence quotient (IQ) in the range of 107 to 115, and Ashkenazi Jews as a group have had successes in intellectual fields far out of proportion to their numbers. A 2005 scientific paper, "Natural History of Ashkenazi Intelligence", proposed that Jews as a group inherit significantly higher verbal and mathematical intelligence and somewhat lower spatial intelligence than other ethnic groups, on the basis of inherited diseases and the peculiar economic situation of Ashkenazi Jews in the Middle Ages. Opposing this hypothesis are explanations for the congenital illnesses in terms of the founder effect and explanations of intellectual successes by reference to Jewish culture's promotion of scholarship and learning.
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  • 14 Oct 2022
Topic Review
Gravitation
In physics, gravitation or gravity is the tendency of objects with mass to accelerate toward each other. Gravitation is one of the four fundamental interactions in nature, the other three being the electromagnetic force, the weak nuclear force, and the strong nuclear force. Gravitation is the weakest of these interactions, but acts over great distances and is always attractive. In classical mechanics, gravitation arises out of the force of gravity (which is often used as a synonym for gravitation). In general relativity, gravitation arises out of spacetime being curved by the presence of mass, and is not a force. In quantum gravity theories, either the graviton is the postulated carrier of the gravitational force, or time-space itself is envisioned as discrete in nature, or both. Classically, the gravitational attraction of the earth endows objects with weight and causes them to fall to the ground when dropped (the earth also moves toward the object, but only by an infinitesimal amount). Moreover, gravitation is the reason for the very existence of the earth, the sun, and other celestial bodies; without it matter would not have coalesced into these bodies and life as we know it would not exist. Gravitation is also responsible for keeping the earth and the other planets in their orbits around the sun, the moon in its orbit around the earth, for the formation of tides, and for various other natural phenomena that we observe.
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  • 14 Oct 2022
Topic Review
Adhan
The adhan, athan, or azaan (Arabic: أَذَان [ʔaˈðaːn]) (also called in Turkish: Ezan) is the Islamic call to worship, recited by the muezzin at prescribed times of the day. The root of the word is ʾadhina أَذِنَ meaning "to listen, to hear, be informed about". Another derivative of this word is ʾudhun (أُذُن), meaning "ear". Adhan is called out by a muezzin from the mosque five times a day, traditionally from the minaret, summoning Muslims for mandatory (fard) worship (salat). A second call, known as iqama, (set up) then summons Muslims to line up for the beginning of the prayers. The main purpose behind the multiple loud pronouncements of adhan in every mosque is to make available to everyone an easily intelligible summary of Islamic belief. In modern times, loudspeakers have been installed on minarets for this purpose. The adhan recites the Takbir (God is great) followed by the Shahada (There is no god but God, Muhammad is the messenger of God). This statement of faith, called the Kalimah, is the first of the Five Pillars of Islam.
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  • 14 Oct 2022
Topic Review
Younger Dryas
The Younger Dryas (around 12,900 to 11,700 years BP) was a return to glacial conditions after the Late Glacial Interstadial, which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM) started receding around 20,000 BP. It is named after an indicator genus, the alpine-tundra wildflower Dryas octopetala, as its leaves are occasionally abundant in late glacial, often minerogenic-rich sediments, such as the lake sediments of Scandinavia. Physical evidence of a sharp decline in temperature over most of the Northern Hemisphere has been discovered by geological research. This temperature change occurred at the end of what the earth sciences refer to as the Pleistocene epoch and immediately before the current, warmer Holocene epoch. In archaeology, this time frame coincides with the final stages of the Upper Paleolithic in many areas. The Younger Dryas was the most recent and longest of several interruptions to the gradual warming of the Earth's climate since the severe LGM, about 27,000 to 24,000 years BP. The change was relatively sudden, taking place in decades, and it resulted in a decline of temperatures in Greenland by 4 to 10°C (7.2 to 18°F) and advances of glaciers and drier conditions, over much of the temperate Northern Hemisphere. It is thought to have been caused by a decline in the strength of the Atlantic meridional overturning circulation, which transports warm water from the Equator towards the North Pole, in turn thought to have been caused by an influx of fresh, cold water from North America to the Atlantic. The Younger Dryas was a period of climatic change, but the effects were complex and variable. In the Southern Hemisphere and some areas of the Northern Hemisphere, such as southeastern North America, a slight warming occurred.
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  • 14 Oct 2022
Topic Review
Enterprise Client-server Backup
Enterprise client-server" backup software describes a class of software applications that back up data from a variety of client computers centrally to one or more server computers, with the particular needs of enterprises in mind. They may employ a scripted client–server backup model with a backup server program running on one computer, and with small-footprint client programs (referred to as "agents" in some applications) running on the other computer(s) being backed up—or alternatively as another process on the same computer as the backup server program. Enterprise-specific requirements include the need to back up large amounts of data on a systematic basis, to adhere to legal requirements for the maintenance and archiving of files and data, and to satisfy short-recovery-time objectives. To satisfy these requirements (which World Backup Day (31 March) highlights), it is typical for an enterprise to appoint a backup administrator—who is a part of office administration rather than of the IT staff and whose role is "being the keeper of the data". In a client-server backup application, the server program initiates the backup activity by the client program. This is distinct from a "personal" backup application such as Apple's Time Machine, in which "Time Machine runs on each Mac, independently of any other Macs, whether they're backing up to the same destination or a different one." If the backup server and client programs are running on separate computers, they are connected in either a single platform or a mixed platform network. The client-server backup model was originated when magnetic tape was the only financially-feasible storage medium for doing backups of multiple computers onto a single archive file;[note 1][note 2] because magnetic tape is a sequential access medium, it was imperative (barring "multiplexed backup") that the client computers be backed up one at a time—as initiated by the backup server program. What is described in the preceding paragraph is the "two-tier" configuration (in one application's diagram, the second-tier backup server program is named "server" preceded by the name of the application, and first-tier "agents" are backing up interactive server applications). That configuration controls the backup server program via either an integrated GUI or a separate Administration Console. In some client-server backup applications, a "three-tier" configuration splits off the backup and restore functions of the server program to run on what are called media servers—computers to which devices containing archive files are attached either locally or as Network-attached storage (NAS). In those applications, the decision on which media server a script is to run on is controlled using another program called either a master server or an optional central admin. server.
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  • 14 Oct 2022
Topic Review
Unintended Consequences
In the social sciences, unintended consequences (sometimes unanticipated consequences or unforeseen consequences) are outcomes of a purposeful action that are not intended or foreseen. The term was popularised in the twentieth century by American sociologist Robert K. Merton and expanded by economist Thomas Sowell and psychologist Stuart Vyse. Unintended consequences can be grouped into three types: Unexpected benefit: A positive unexpected benefit (also referred to as luck, serendipity or a windfall). Unexpected drawback: An unexpected detriment occurring in addition to the desired effect of the policy (e.g., while irrigation schemes provide people with water for agriculture, they can increase waterborne diseases that have devastating health effects, such as schistosomiasis). Perverse result: A perverse effect contrary to what was originally intended (when an intended solution makes a problem worse).
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  • 14 Oct 2022
Topic Review
Urban Open Space
In land-use planning, urban open space is open-space areas reserved for parks, "green spaces", and other open areas. The landscape of urban open spaces can range from playing fields to highly maintained environments to relatively natural landscapes. Generally considered open to the public, urban open spaces are sometimes privately owned, such as higher education campuses, neighborhood/community parks/gardens, and institutional or corporate grounds. Areas outside city boundaries, such as state and national parks as well as open space in the countryside, are not considered urban open space. Streets, piazzas, plazas and urban squares are not always defined as urban open space in land use planning.
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  • 14 Oct 2022
Topic Review
Range Encoding
Range encoding is an entropy coding method defined by G. Nigel N. Martin in a 1979 paper, which effectively rediscovered the FIFO arithmetic code first introduced by Richard Clark Pasco in 1976. Given a stream of symbols and their probabilities, a range coder produces a space-efficient stream of bits to represent these symbols and, given the stream and the probabilities, a range decoder reverses the process. Range coding is very similar to arithmetic encoding, except that encoding is done with digits in any base, instead of with bits, and so it is faster when using larger bases (e.g. a byte) at small cost in compression efficiency. After the expiration of the first (1978) arithmetic coding patent, range encoding appeared to clearly be free of patent encumbrances. This particularly drove interest in the technique in the open source community. Since that time, patents on various well-known arithmetic coding techniques have also expired.
  • 1.1K
  • 14 Oct 2022
Topic Review
Intel MCS-51
The Intel MCS-51 (commonly termed 8051) is a single chip microcontroller (MCU) series developed by Intel in 1980 for use in embedded systems. The architect of the Intel MCS-51 instruction set was John H. Wharton. Intel's original versions were popular in the 1980s and early 1990s and enhanced binary compatible derivatives remain popular today. It is an example of a complex instruction set computer, and has separate memory spaces for program instructions and data. Intel's original MCS-51 family was developed using N-type metal-oxide-semiconductor (NMOS) technology like its predecessor Intel MCS-48, but later versions, identified by a letter C in their name (e.g., 80C51) use complementary metal–oxide–semiconductor (CMOS) technology and consume less power than their NMOS predecessors. This made them more suitable for battery-powered devices. The family was continued in 1996 with the enhanced 8-bit MCS-151 and the 8/16/32-bit MCS-251 family of binary compatible microcontrollers. While Intel no longer manufactures the MCS-51, MCS-151 and MCS-251 family, enhanced binary compatible derivatives made by numerous vendors remain popular today. Some derivatives integrate a digital signal processor (DSP). Beyond these physical devices, several companies also offer MCS-51 derivatives as IP cores for use in field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC) designs.
  • 6.9K
  • 14 Oct 2022
Topic Review
Ring-Tailed Cat
The ringtail (Bassariscus astutus) is a mammal of the raccoon family native to arid regions of North America. It is widely distributed and well adapted to disturbed areas. It has been legally trapped for its fur. It is listed as Least Concern on the IUCN Red List. It is also known as the ringtail cat, ring-tailed cat, miner's cat or bassarisk, and is sometimes called a cacomistle, though this term seems to be more often used to refer to Bassariscus sumichrasti.
  • 2.5K
  • 14 Oct 2022
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