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6061 Aluminium Alloy
6061 (Unified Numbering System (UNS) designation A96061) is a precipitation-hardened aluminium alloy, containing magnesium and silicon as its major alloying elements. Originally called "Alloy 61S", it was developed in 1935. It has good mechanical properties, exhibits good weldability, and is very commonly extruded (second in popularity only to 6063). It is one of the most common alloys of aluminum for general-purpose use. It is commonly available in pre-tempered grades such as 6061-O (annealed), tempered grades such as 6061-T6 (solutionized and artificially aged) and 6061-T651 (solutionized, stress-relieved stretched and artificially aged).
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  • 22 Nov 2022
Topic Review
Void Coefficient
In nuclear engineering, the void coefficient (more properly called void coefficient of reactivity) is a number that can be used to estimate how much the reactivity of a nuclear reactor changes as voids (typically steam bubbles) form in the reactor moderator or coolant. Net reactivity in a reactor is the sum total of all these contributions, of which the void coefficient is but one. Reactors in which either the moderator or the coolant is a liquid typically will have a void coefficient value that is either negative (if the reactor is under-moderated) or positive (if the reactor is over-moderated). Reactors in which neither the moderator nor the coolant is a liquid (e.g., a graphite-moderated, gas-cooled reactor) will have a void coefficient value equal to zero. It is unclear how the definition of 'void' coefficient applies to reactors in which the moderator/coolant is neither liquid nor gas (supercritical water reactor).
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  • 22 Nov 2022
Topic Review
Independent Legal Reasoning in Islamic Law
Ijtihad (Arabic: اجتهاد ijtihād, [ʔidʒ.tihaːd]; lit. physical or mental effort) is an Islamic legal term referring to independent reasoning by an expert in Islamic law, or the thorough exertion of a jurist's mental faculty in finding a solution to a legal question. It is contrasted with taqlid (imitation, conformity to legal precedent). According to classical Sunni theory, ijtihad requires expertise in the Arabic language, theology, revealed texts, and principles of jurisprudence (usul al-fiqh), and is not employed where authentic and authoritative texts (Qur'an and Hadith) are considered unambiguous with regard to the question, or where there is an existing scholarly consensus (ijma). Ijtihad is considered to be a religious duty for those qualified to perform it. An Islamic scholar who is qualified to perform ijtihad is called a mujtahid. Throughout the first five Islamic centuries, the practice of ijtihad continued both theoretically and practically amongst Sunni Muslims. The controversy surrounding ijtihad and the existence of mujtahids started, in its primitive form, around the beginning of the sixth/twelfth century. By the 14th century, development of Sunni jurisprudence prompted leading Sunni jurists to state that the main legal questions had been addressed and the scope of ijtihad was gradually restricted. In the modern era, this gave rise to a perception among Western scholars and lay Muslim public that the so-called "gate of ijtihad" was closed at the start of the classical era. While recent scholarship established that the practice of Ijtihad had never ceased in Islamic history, the extent and mechanisms of legal change in the post-formative period remain a subject of debate. Differences amongst the jurists prevented Muslims from reaching any consensus(Ijma) on the issues of continuity of Ijtihad and existence of Mujtahids. Thus, Ijtihad remained a key aspect of Islamic jurisprudence throughout the centuries. Ijtihad was practiced throughout the Early modern period and claims for ijtihad and its superiority over taqlid were voiced unremittingly. Starting from the 18th century, Islamic reformers began calling for abandonment of taqlid and emphasis on ijtihad, which they saw as a return to Islamic origins. Public debates in the Muslim world surrounding ijtihad continue to the present day. The advocacy of ijtihad has been particularly associated with Islamic modernist and Salafiyya movements. Among contemporary Muslims in the West there have emerged new visions of ijtihad which emphasize substantive moral values over traditional juridical methodology. Shia jurists did not use the term ijtihad until the 12th century. With the exception of Zaydi jurisprudence, the early Imami Shia were unanimous in censuring Ijtihad in the field of law (Ahkam). After the Shiite embracal of various doctrines of Mu'tazila and classical Sunnite Fiqh (jurisprudence), this led to a change. After the victory of the Usulis who based law on principles (usul) over the Akhbaris ("traditionalists") who emphasized on reports or traditions (khabar) by the 19th century, Ijtihad would become a mainstream Shia practice.
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  • 22 Nov 2022
Topic Review
Allan Hills 84001
Allan Hills 84001 (ALH84001) is a fragment of a Martian meteorite that was found in the Allan Hills in Antarctica on December 27, 1984, by a team of American meteorite hunters from the ANSMET project. Like other members of the shergottite–nakhlite–chassignite (SNC) group of meteorites, ALH84001 is thought to have originated on Mars. However, it does not fit into any of the previously discovered SNC groups. Its mass upon discovery was 1.93 kilograms (4.3 lb). In 1996, a group of scientists found evidence of microscopic fossils of bacteria in the meteorite, suggesting that these organisms also originated on Mars. The claims immediately made headlines worldwide, culminating in then-U.S. president Bill Clinton giving a speech about the potential discovery. These claims were controversial from the beginning, and the wider scientific community ultimately rejected the hypothesis once all the unusual features in the meteorite had been explained without requiring life to be present. Despite there being no convincing evidence of Martian life, the initial paper and the enormous scientific and public attention caused by it are considered turning points in the history of the developing science of astrobiology.
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  • 22 Nov 2022
Topic Review
Parisoma
Coordinates: 37°46′24.89″N 122°24′57.19″W / 37.7735806°N 122.4158861°W / 37.7735806; -122.4158861 Parisoma (/ˈpærɪˈsoʊmə/) is a coworking space and open incubator in the SoMa district of San Francisco founded and managed by the firm Fabernovel. In addition to providing shared work space to approximately 120 members, it also hosts events and classes related to design, business, technology, and entrepreneurship.
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  • 22 Nov 2022
Topic Review
Close Quarters Combat
Close quarters combat (CQC) is a tactical concept that involves physical confrontation between several combatants. It can take place between military units, police/corrections and criminals, and other similar scenarios. In warfare, it usually consists of small units or teams engaging the enemy with personal weapons at very short range, up to 100 meters, from proximity hand-to-hand combat to close-quarter target negotiation with short-range firearms. In the typical close quarters combat scenario, the attackers try a very fast, violent takeover of a vehicle or structure controlled by the defenders, who usually have no easy way to withdraw. Because enemies, hostages/civilians, and fellow operators can be closely intermingled, close quarters combat demands a rapid assault and a precise application of lethal force. The operators need great proficiency with their weapons, and the ability to make split-second decisions in order to minimize accidental casualties. Criminals sometimes use close quarters combat techniques, such as in an armed robbery or jailbreak, but most of the terminology comes from training used to prepare soldiers, police/corrections, and other authorities. Therefore, much material relating to close quarters combat is written from the perspective of the authorities who must break into the stronghold where the opposing force has barricaded itself. Typical examples would be commando operations behind enemy lines and hostage rescues. Although there is considerable overlap, close quarters combat is not synonymous with urban warfare, now sometimes known by the military acronyms MOUT (military operations in urban terrain), FIBUA (fighting in built-up areas) or OBUA (Operations in Built Up Areas) in the West. Urban warfare is a much larger field, including logistics and the role of crew-served weapons like heavy machine guns, mortars, and mounted grenade launchers, as well as artillery, armor, and air support. In close quarters combat, the emphasis is on small infantry units using light, compact weapons that one person can carry and use easily in tight spaces, such as carbines, submachine guns, shotguns, pistols, knives, and bayonets. As such, close quarters combat is a tactical concept that forms a part of the strategic concept of urban warfare, but not every instance of close quarters combat is necessarily urban warfare—for example, a jungle is potentially a stage for close quarters combat.
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Biography
William R. Blair
William Richards Blair (November 7, 1874 – September 2, 1962) was an American scientist and U.S. Army officer, who worked on the development of the radar in United States starting during the 1930s. He led the U.S. Army's Signal Corps Laboratories during its formative years and is often called the "Father of American Radar".[1] Blair was born in Ireland in County Londonderry on November 7, 1
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Biography
Larry Smarr
Larry Lee Smarr is a physicist and leader in scientific computing, supercomputer applications, and Internet infrastructure at the University of California, San Diego.[1][2][3][4][5][6][7][8][9][10][11] Smarr has been among the most important synthesizers and conductors of innovation, discovery, and commercialization of new technologies — including areas as disparate as the Web browser and pers
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  • 22 Nov 2022
Biography
Marco Visconti
Marco Visconti (born 4 June 1978) is an Italian occultist and musician.[1] He is known for his work with the musical group XP8[2] and Faderhead.[3] Under the name Azrael[4] Visconti is an past officer[5] of the Thelemic organisation Ordo Templi Orientis (O.T.O.) in London,[6] and scholar of the occult works of English author Aleister Crowley, the founder of the philosophy and religion of Thelema
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Biography
Alexei Alexeyevich Abrikosov
Alexei Alexeyevich Abrikosov (Russian: Алексе́й Алексе́евич Абрико́сов; June 25, 1928 – March 29, 2017[1][2]) was a Soviet, Russia n and American[3] theoretical physicist whose main contributions are in the field of condensed matter physics. He was the co-recipient of the 2003 Nobel Prize in Physics, with Vitaly Ginzburg and Anthony James Leggett, for theories abou
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