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  • Aden (Yemen)
    city of Yemen. It is situated along the north coast of the Gulf of Aden and lies on a peninsula enclosing the eastern side of Al-Tawāhī Harbour. The peninsula enclosing the western side of the harbour is called Little Aden....
  • Aden, Gulf of (gulf, Arabian Sea)
    deepwater basin that forms a natural sea link between the Red Sea and the Arabian Sea. Named for the seaport of Aden, in southern Yemen, the gulf is situated between the coasts of Arabia and the Horn of Africa. To the west, it narrows into the Gulf of Tadjoura; its eastern geographic limits are defined by the meridian of Cape Guardafui (51...
  • Aden, University of (university, Aden, Yemen)
    ...Sanaa (founded 1970), established largely with grants from Kuwait, is coeducational and comprises a variety of specialized colleges—e.g., those of agriculture, medicine, commerce, and law. The University of Aden (1975) offers a similar array of specialties. These two senior institutions of higher learning have spawned universities and colleges throughout Yemen, and there are now several....
  • Adena culture (anthropology)
    culture of various communities of ancient North American Indians, about 500 bc–ad 100, centred in what is now southern Ohio. Groups in Indiana, Kentucky, West Virginia, and possibly Pennsylvania bear similarities and are roughly grouped with the Adena culture. (The term Adena derives from the home of an early Ohio governor, located near Chillicothe, Ohio, around...
  • Adena Serpent Mound (earthwork, Ohio, United States)
    Ritual structures existed, such as the so-called effigy mounds—great piles of earth fashioned to represent a variety of animals. The Serpent Mound in Ohio is an example of this custom. Truncated pyramids served as large bases for wooden temples, now long vanished but still in use when Spanish explorers first entered the region. Monks Mound, dominating the Cahokia Mounds, near......
  • Adenauer, Konrad (chancellor of West Germany)
    first chancellor of the Federal Republic of Germany (West Germany; 1949–63), presiding over its reconstruction after World War II. A Christian Democrat and firmly anticommunist, he supported the North Atlantic Treaty Organization (NATO) and worked to reconcile Germany with its former enemies, especially France....
  • Adenet le Roi (French poet and musician)
    poet and musician, interesting for the detailed documentary evidence of his career as a household minstrel....
  • Adenia (plant genus)
    ...when immature, although the mature fruit has been known to be poisonous. P. incarnata has an ingredient used in sedatives, and the flowers of P. x belotii are used to make scent. Adenia (about 100 species), which is native to tropical Africa and Asia, makes up most of the remaining species in the family. A. volkensii, of tropical Africa, is poisonous to humans,......
  • adenine (chemical compound)
    organic compound belonging to the purine family, occurring free in tea or combined in many substances of biological importance, including the nucleic acids, which govern hereditary characteristics of all cells....
  • Adenium multiflorum (plant)
    ...and Amsonia sometimes are grown as ornamentals. The genera Adenium and Pachypodium are African succulents with alternate leaves and strangely shaped trunks. The impala lily (Adenium multiflorum) is an ornamental shrub with star-shaped flowers and large underground tubers. Arrow poisons are obtained from many plants in the dogbane family, and the......
  • adenocarcinoma (tumour)
    ...provide a passage for milk (ductal tissue) to the nipple. Cancers of these tissues are called lobular carcinomas and ductal carcinomas. Because these tissues are glandular, both cancers are called adenocarcinomas. The most common type of tumour, called infiltrating ductal carcinoma, is a single hard, barely movable lump. This type of tumour accounts for about 70 percent of all cases. Fewer......
  • adenochrome (biology)
    Adenochrome is a nonproteinaceous pigment that occurs as garnet-red inclusions at high concentrations in the glandular, branchial heart tissues of Octopus bimaculatus. The compound contains small amounts of ferric iron and some nitrogen and gives a positive reaction for pyrroles. It is believed to be an excretory product. ...
  • adenohypophysis (anatomy)
    The pituitary gland (also called the hypophysis) is situated at the base of the brain. The gland itself is composed of three distinct lobes: the anterior lobe (also called the adenohypophysis), the posterior lobe (also called the neurohypophysis), and the intermediate lobe (or pars intermedia). The pituitary gland is connected by a bridge, the pituitary stalk, through which it receives its......
  • adenoiditis (disease)
    Enlargement of the adenoids (lymphoid tissue in the nasal part of the pharynx) as a result of recurrent infection can result in mouth breathing and a so-called adenoidal facial appearance, the most conspicuous feature of which is the constantly open mouth. By blocking the eustachian tube, it can contribute to infections of the middle ear (otitis media) and to hearing loss. In children with......
  • adenoids (human anatomy)
    a mass of lymphatic tissue, similar to the (palatine) tonsils, that is attached to the back wall of the nasal pharynx (i.e., the upper part of the throat opening into the nasal cavity proper). An individual fold of such nasopharyngeal lymphatic tissue is called an adenoid....
  • adenoma (tumour)
    Just as adenoma designates a benign tumour of epithelial origin that takes on a glandlike structure, so adenocarcinoma designates a malignant epithelial tumour with a similar growth pattern. Usually the term is followed by the organ of origin—e.g., adenocarcinoma of the lung....
  • adenosine deaminase deficiency (pathology)
    Adenosine deaminase (ADA) deficiency results in the accumulation of 2′-deoxyadenosine in the circulating white blood cells (lymphocytes). This, in turn, causes a decreased number of lymphocytes and a drastically increased susceptibility to infection (severe combined immunodeficiency, SCID). Bone marrow transplantation may be curative, and gene therapy has shown promise, but enzyme......
  • adenosine diphosphate (coenzyme)
    Adenosine monophosphate, diphosphate, and triphosphate (AMP, ADP, and ATP, respectively) are important participants in energy processes in the living cell. Each of the compounds is composed of the nucleotide base adenine linked to the sugar ribose, which in turn is linked to a linear “tail” of one, two, or three phosphate groups, respectively, as shown....
  • adenosine monophosphate (coenzyme)
    Adenosine monophosphate, diphosphate, and triphosphate (AMP, ADP, and ATP, respectively) are important participants in energy processes in the living cell. Each of the compounds is composed of the nucleotide base adenine linked to the sugar ribose, which in turn is linked to a linear “tail” of one, two, or three phosphate groups,......
  • adenosine phosphate (coenzyme)
    Adenosine monophosphate, diphosphate, and triphosphate (AMP, ADP, and ATP, respectively) are important participants in energy processes in the living cell. Each of the compounds is composed of the nucleotide base adenine linked to the sugar ribose, which in turn is linked to a linear “tail” of one, two, or three phosphate groups,......
  • adenosine phosphosulfate (chemical compound)
    ...in the soil, which is reduced in the cell. In plants and bacteria that utilize sulfate as a source of sulfur, the first step in the reduction process is the formation of adenosine phosphosulfate (APS), since direct reduction of sulfate itself is extremely difficult. The −OSO2O1− group of APS is reduced to a sulfite ion......
  • adenosine triphosphatase (enzyme)
    An enzyme called sodium-potassium-activated ATPase has been shown to be the sodium-potassium pump, the protein that transports the ions across the cell membrane while splitting ATP. Widely distributed in the animal kingdom and always associated with the cell membrane, this ATPase is found at high concentration in cells that pump large amounts of sodium (e.g., in mammalian kidneys, in......
  • adenosine triphosphate (coenzyme)
    energy-carrying molecule found in the cells of all living things. ATP captures chemical energy obtained from the breakdown of food molecules and releases it to fuel other cellular processes....
  • Adenoviridae (virus group)
    any virus belonging to the family Adenoviridae. This group of viruses was discovered in the 1950s and includes 6 genera and 47 species (formerly referred to as serotypes) that cause sore throat and fever in humans, hepatitis in dogs, and several diseases in fowl, mice, cattle, pigs, and monkeys. The virus particle lacks an outer envelope; is...
  • adenovirus (virus group)
    any virus belonging to the family Adenoviridae. This group of viruses was discovered in the 1950s and includes 6 genera and 47 species (formerly referred to as serotypes) that cause sore throat and fever in humans, hepatitis in dogs, and several diseases in fowl, mice, cattle, pigs, and monkeys. The virus particle lacks an outer envelope; is...
  • adenovirus infection
    any virus belonging to the family Adenoviridae. This group of viruses was discovered in the 1950s and includes 6 genera and 47 species (formerly referred to as serotypes) that cause sore throat and fever in humans, hepatitis in dogs, and several diseases in fowl, mice, cattle, pigs, and monkeys. The virus particle lacks an outer envelope; is...
  • adenyl cyclase (enzyme)
    ...of itself. Other molecules act as activators; i.e., they interact with an enzyme so as to enhance the binding of the substrate to the enzyme, thus enhancing catalytic activity. The enzyme adenyl cyclase, itself activated by the hormone adrenaline (epinephrine), which is released when a mammal requires energy, catalyzes a reaction that results in the formation of the compound cyclic......
  • adenyl phosphoric acid (chemistry)
    Embden and his co-workers isolated several intermediate metabolic products from muscle tissue and discovered the important metabolic compound adenyl phosphoric acid, which is more commonly known as adenosine triphosphate (ATP). In all his work he emphasized the relationships between his results and general cellular processes....
  • adenylate cyclase (enzyme)
    ...of itself. Other molecules act as activators; i.e., they interact with an enzyme so as to enhance the binding of the substrate to the enzyme, thus enhancing catalytic activity. The enzyme adenyl cyclase, itself activated by the hormone adrenaline (epinephrine), which is released when a mammal requires energy, catalyzes a reaction that results in the formation of the compound cyclic......
  • adenylic acid (chemistry)
    Embden and his co-workers isolated several intermediate metabolic products from muscle tissue and discovered the important metabolic compound adenyl phosphoric acid, which is more commonly known as adenosine triphosphate (ATP). In all his work he emphasized the relationships between his results and general cellular processes....
  • adenylyl cyclase (enzyme)
    ...of itself. Other molecules act as activators; i.e., they interact with an enzyme so as to enhance the binding of the substrate to the enzyme, thus enhancing catalytic activity. The enzyme adenyl cyclase, itself activated by the hormone adrenaline (epinephrine), which is released when a mammal requires energy, catalyzes a reaction that results in the formation of the compound cyclic......
  • Adeodatus (son of Augustine)
    ...after some soul-searching and apparent idleness, made his way back to his native town of Tagaste. There he passed the time as a cultured squire, looking after his family property, raising the son, Adeodatus, left him by his long-term lover (her name is unknown) taken from the lower classes, and continuing his literary pastimes. The death of that son while still an adolescent left Augustine......
  • Adeodatus I (pope)
    pope from 615 to 618. His pontificate is chiefly noteworthy for an unsuccessful resumption of the Byzantine war against the Lombards in Italy and for a reversal of the policy of popes Gregory I and Boniface IV, who favoured monks over the secular clergy. Deusdetit, instead, proved partial to the diocesan, or secular, clergy....
  • Adeodatus II (pope)
    pope (672–676) who was the first pontiff to date events in terms of his reign, which began with his election on April 11, 672....
  • Adequate Intake (diet)
    ...requirement of nearly all (97 to 98 percent) healthy persons in a particular life stage. When the EAR, and thus the RDA, cannot be set due to insufficient scientific evidence, another parameter, the Adequate Intake (AI), is given, based on estimates of intake levels of healthy populations. Lastly, the Tolerable Upper Intake Level (UL) is the highest level of a daily nutrient intake that will......
  • Ader Avion III (French aircraft)
    monoplane designed, built, and first tested by the French aeronautical pioneer Clément Ader in 1897. For a table of pioneer aircraft, see history of flight....
  • Ader, Clément (French inventor)
    self-taught French engineer, inventor, and aeronautical pioneer....
  • Ader Éole (French aircraft)
    monoplane designed, built, and first tested by the French aeronautical pioneer Clément Ader in 1890. For a table of pioneer aircraft, see history of flight....
  • Adere (people)
    ...supplemented by oilseed pressing and the processing of sansevieria fibre. Basket weaving is a commercially important craft, as is the production of silver jewelry. The population includes the local Hareri (Adere), who speak a Semitic language and have a literature written in Arabic script, as well as the Amhara, Oromo, and Somalis. The Hārer Military Academy is situated in the town. A......
  • Adere language
    ...Orthodox church; Amharic, one of the principal languages of modern Ethiopia; Tigré, of northwestern Eritrea and Sudan; Tigrinya, or Tigrai, of northern Ethiopia and central Eritrea; Argobba; Hareri; and Gurage. Although some scholars once considered the so-called Ethiopic languages to be a branch within Semitic, these languages are now referred to as Ethio-Semitic. They are generally......
  • Adernò (Italy)
    town, eastern Sicily, Italy. It lies near the Simeto River on a lava plateau on the western slopes of Mount Etna, northwest of Catania city. It originated as the ancient town of Hadranon, founded about 400 bc by Dionysius I, tyrant of Syracuse, near a sanctuary dedicated to the Siculan god Adranus (Hadranus). Conquered in 263 bc by ...
  • Adesmoidea (mollusk)
    any of the marine bivalve mollusks of the family Pholadidae (Adesmoidea). Worldwide in distribution, they are especially adapted for boring into rock, shells, peat, hard clay, or mud. Most species occur in the intertidal zone, a few in deeper water....
  • ADF (Middle Eastern military force)
    ...2,000 to 3,000 Palestinians in the Tall al-Zaʿtar camp northeast of Beirut. A peace agreement was negotiated in October 1976. The settlement provided for the creation of a 30,000-member Arab Deterrent Force (ADF), a cease-fire throughout the country, withdrawal of forces to positions held before April 1975, and implementation of a 1969 agreement limiting Palestinian guerrilla......
  • ADF (instrument)
    radio receiver and directional antenna system used to determine the direction of the source of a signal. It most often refers to a device used to check the position of a ship or aircraft, although it may also direct a craft’s course or be used for military or investigative purposes....
  • ADFGVX cipher
    ...a biliteral cipher) in the ciphertext, which was then encrypted by a final transposition, known as superencryption. One of the most famous field ciphers of all time was a fractionation system, the ADFGVX cipher employed by the German army during World War I. This system used a 6 × 6 matrix to substitution-encrypt the 26 letters and 10 digits into pairs of the symbols A, D, ...
  • ADH (enzyme)
    ...intestine. In general, a lower percentage of the alcohol is degraded in a young woman’s stomach than in a young man’s because a young woman’s gastric secretions contain lower levels of the enzyme alcohol dehydrogenase (ADH), which breaks down alcohol prior to absorption....
  • ADH (biochemistry)
    Vasopressin (antidiuretic hormone) and oxytocin evolved from a single primordial neurohypophyseal hormone called vasotocin, which is present in lower vertebrates. Within the secretory granules of nerve cells, each hormone is loosely attached to neurophysin, from which the hormone separates when the granule is discharged into the bloodstream....
  • Adhaim (river, Iraq)
    ...irrigation areas behind a number of dams. The Tigris, in contrast, flows down the edge of a long, multichanneled catchment basin and is fed by four strong tributaries, the Great Zab, Little Zab, ʿUẓaym, and Diyālá rivers, all of which derive their water mainly from snowmelt in Turkish, Iranian, and Iraqi Kurdistan. The precipitous flow of its tributaries makes the......
  • Adham Khān (Mughal captain)
    ...ability then followed in quick succession. Although not yet his own master, Akbar took a few momentous steps during that period. He conquered Malwa (1561) and marched rapidly to Sarangpur to punish Adham Khan, the captain in charge of the expedition, for improper conduct. Second, he appointed Shams al-Dīn Muḥammad Atgah Khan as prime minister (November 1561). Third, at about the.....
  • adhān (Islam)
    (Arabic: “announcement”), the Muslim call to Friday public worship and to the five daily hours of prayer. It is proclaimed by the muezzin, a servant of the mosque chosen for good character, as he stands at the door or side of a small mosque or in the minaret of a large one. The adhān was originally a simple “Come to prayer,” but, accord...
  • adharma (Jainism)
    ...or “living matter.” Ajiva is divided into: (1) ākāśa, “space,” (2) dharma, “that which makes motion possible,” (3) adharma, “that which makes rest possible,” and (4) pudgala, “matter.” Pudgala consists of atoms; is eternal yet subject to change and development;......
  • ADHD (pathology)
    a behavioral syndrome characterized by inattention and distractibility, restlessness, inability to sit still, and difficulty concentrating on one thing for any period of time. ADHD most commonly occurs in children, though an increasing number of adults are being diagnosed with the disorder. ADHD is three times more common in males than in females and occurs in approximately 3 to...
  • Adhémar de Chabannes (Frankish historian)
    Frankish chronicler whose major work, Chronicon Aquitanicum et Francicum (“Chronicle of Aquitaine and France”), traces the history of Aquitaine and of the Franks from the times of the legendary king Pharamond....
  • Adhémar of Monteil (French bishop and crusader)
    French bishop, papal legate, and a leader of the First Crusade....
  • Adhémar of Puy (French bishop and crusader)
    French bishop, papal legate, and a leader of the First Crusade....
  • Adherbal (Numidian leader)
    After Micipsa’s death in 118, Jugurtha shared the rule of Numidia with Micipsa’s two sons, Hiempsal and Adherbal, the first of whom Jugurtha assassinated. When Adherbal was attacked by Jugurtha, he fled to Rome for aid—Rome’s approval being required for any change in the government of Numidia. A senatorial commission divided Numidia, with Jugurtha taking the less-develo...
  • adhering junction (biology)
    Cells subject to abrasion or other mechanical stress, such as those of the surface epithelia of the skin, have junctions that adhere cells to one another and to the extracellular matrix. These adhering junctions are called desmosomes when occurring between cells and hemidesmosomes (half-desmosomes) when linked to the matrix. Adhering junctions distribute mechanical shear force throughout the......
  • adhesion (medicine)
    Cells subject to abrasion or other mechanical stress, such as those of the surface epithelia of the skin, have junctions that adhere cells to one another and to the extracellular matrix. These adhering junctions are called desmosomes when occurring between cells and hemidesmosomes (half-desmosomes) when linked to the matrix. Adhering junctions distribute mechanical shear force throughout the.........
  • adhesion (physics)
    The supercooling of river water, while amounting to only a few hundredths of a degree Celsius or even less, provides the context for the particles to stick to one another, since under such conditions ice particles are inherently unstable and actively grow into the supercooled water. When they touch one another or some other surface that is cooled below the freezing point, they adhere by......
  • adhesion contract (law)
    ...life in which the parties to contracts have such unequal bargaining positions that little real negotiation takes place. These contracts are often known as contracts of adhesion. Familiar examples of adhesion contracts are contracts for transportation or service concluded with public carriers and utilities and contracts of large corporations with their suppliers, dealers, and customers. In such....
  • adhesion molecule (biochemistry)
    ...the 1970s Edelman shifted his research to focus on questions outside of immunology: specifically, how the body—the brain in particular—develops. In 1975 he discovered substances called cell adhesion molecules (CAMs), which “glue” cells together to form tissues. Edelman found that, as the brain develops, CAMs bind neurons together to form the brain’s basic circ...
  • adhesive (chemistry)
    any substance that is capable of holding materials together in a functional manner by surface attachment that resists separation. “Adhesive” as a general term includes cement, mucilage, glue, and paste—terms that are often used interchangeably for any organic material that forms an adhesive bond. Inorganic substances such as portland cement also can be considered adhesives, in...
  • adhesive tissue tape
    ...a source of contamination and are used infrequently. Staples permit faster closure of the skin but are less precise than sutures. When the edges can be brought together easily and without tension, tape is very useful. Although it is comfortable, easy to apply, and avoids the marks left by sutures, tape may come loose or be removed by the patient and is less successful if much wound edema......
  • adhidaivata (Indian philosophy)
    ...Advaita (nondualist) Vedānta. The nirukta (etymology) of Yāska, a 5th-century- bc Sanskrit scholar, tells of various attempts to interpret difficult Vedic mythologies: the adhidaivata (pertaining to the deities), the aitihāsika (pertaining to the tradition), the adhiyajña (pertaining to the sacrifices), and the......
  • Adhikāranandin (Hindu mythology)
    bull vāhana (mount) of the Hindu god Śiva. Some scholars suggest that the bull was originally the zoomorphic form of Śiva, but from the Kuṣāṇa (Kushan) age onward (c. 1st century ad), he is identified as the god’s vehicle....
  • Adhikari, Man Mohan (prime minister of Nepal)
    Nepalese politician who dedicated most of his adult life to the fight against the monarchy and authoritarian rule; in 1994–95 he served as Nepal’s first communist prime minister for about nine months, during which he initiated a number of reforms, such as a build-your-own-village program to direct money to poor villages (b. June 1920, Lazimpat, Kathmandu, Nepal—d. April 26, 19...
  • adhipati-pratyaya (Buddhist philosophy)
    ...(3) the object as a cause (ālambana-pratyaya), since the object present in the preceding moment becomes the cause of the mental activity for functioning; and (4) the superior cause (adhipati-pratyaya), which refers to all causes, except those stated above, that are effective to produce a thing or not to hinder the existence of it. In the latter sense, every existence can be...
  • adhiyajña (Indian philosophy)
    ...scholar, tells of various attempts to interpret difficult Vedic mythologies: the adhidaivata (pertaining to the deities), the aitihāsika (pertaining to the tradition), the adhiyajña (pertaining to the sacrifices), and the ādhyātmika (pertaining to the spirit). Such interpretations apparently prevailed in the Upaniṣads; the......
  • Adhruḥ, arbitration of (Islamic history [658-59])
    ...for vengeance on ʿUthmān’s death and questioned the validity of ʿAlī’s caliphate. Their confrontation in the Battle of Ṣiffīn (657), which the arbitration at Adhruḥ (659) attempted to resolve, was disastrous: it split ʿAlī’s forces, some of his followers (Khawārij) refusing to acknowledge the validity of ...
  • Adhur-Narses (Sāsānian prince)
    Little is known of Hormizd’s reign, although according to one ancient source he executed some members of the Manichaean religion. At Hormizd’s death powerful nobles killed his son Adhur-Narses, who had assumed the throne, and imprisoned another son, Hormizdas. In 324 Hormizdas escaped to the court of the Roman emperor Constantine the Great. ...
  • adhyāsa (Indian philosophy)
    Human perception of the unitary and infinite Brahman as the plural and infinite is due to human beings’ innate habit of superimposition (adhyāsa), by which a thou is ascribed to the I (I am tired; I am happy; I am perceiving). The habit stems from human ignorance (ajñāna, avidyā), which can be avoided only by the realization of the identity o...
  • adhyātmavidyā (Indian philosophy)
    The role of the sacred texts in the growth of Indian philosophy is different in each of the different systems. In those systems that may be called adhyātmavidyā, or sciences of spirituality, the sacred texts play a much greater role than they do in the logical systems (ānvīkṣikīvidyā). In the case of the former, Śaṅkara, ...
  • ādhyātmika (Indian philosophy)
    ...mythologies: the adhidaivata (pertaining to the deities), the aitihāsika (pertaining to the tradition), the adhiyajña (pertaining to the sacrifices), and the ādhyātmika (pertaining to the spirit). Such interpretations apparently prevailed in the Upaniṣads; the myths were turned into symbols, though some of them persisted as.....
  • Adī (people)
    Arunāchal Pradesh is the homeland of several groups—the Abor or Adi, Aka, Apa Tani, Daflā, Khāmptī, Khowā, Mishmi,......
  • Adi Brahmo Samaj (Hinduism)
    (Sanskrit: “Society of Brahmā”), quasi-Protestant, theistic movement within Hinduism, founded in Calcutta in 1828 by Ram Mohun Roy. The Brahmo Samaj does not accept the authority of the Vedas, has no faith in avatars (incarnations), and does not insist on belief in karma (causal effects of past deeds) or rebirth. It discards Hindu rituals and adopts some Ch...
  • Adi Da (religious leader)
    a small religious movement grounded in the Hindu tradition. Founded in 1972 in California by Franklin Jones (born 1939), who changed his name to Adi Da (Sanskrit: “One Who Gives from the Divine Source”) in 1994, it has undergone a number of name changes and considerable internal turmoil....
  • Ādi Granth (Sikh sacred scripture)
    (Punjabi: “First Book”), the sacred scripture of Sikhism, a religion of India. The book (also known as Granth, or Granth Sahib [“The Granth Personified”]) is a collection of nearly 6,000 hymns of the Sikh Gurūs (religious leaders) and various early and medieval saints of different religions and castes....
  • ʿAdī, Shaykh (Yazīdī leader)
    ...his sin of pride before God, he was pardoned and replaced in his previous position as chief of the angels; this myth has earned the Yazīdī an undeserved reputation as devil worshipers. Shaykh ʿAdī, the chief Yazīdī saint, was a 12th-century Muslim mystic whom the Yazīdī believe to have achieved divinity through metempsychosis....
  • Adi Sri Guru Granth Sahibji (Sikh sacred scripture)
    (Punjabi: “First Book”), the sacred scripture of Sikhism, a religion of India. The book (also known as Granth, or Granth Sahib [“The Granth Personified”]) is a collection of nearly 6,000 hymns of the Sikh Gurūs (religious leaders) and various early and medieval saints of different religions and castes....
  • Ādi-Buddha (Buddhism)
    among some sects of Mahāyāna Buddhism, the first, or self-existing, Buddha, from whom are said to have evolved the five Dhyāni-Buddhas (see Dhyāni-Buddha). Though the concept of an Ādi-Buddha was never generally popular, a few groups, particularly in Nepal, Tibet, and Java, elevated Vairocana to the position of Ādi-Buddha or name...
  • adiabatic change (physics)
    in thermodynamics, change occurring within a system as a result of transfer of energy to or from the system in the form of work only. A rapid expansion or contraction of a gas is very nearly adiabatic. Any process that occurs within a container that is a good thermal insulator is also adiabatic. Adiabatic processes are characterized by an increase in entropy, or degree of disor...
  • adiabatic compressibility (physics)
    ...changes when the pressure is changed by a small amount, and this is described by the compressibility of the fluid—either the isothermal compressibility, βT, or the adiabatic compressibility, βS, according to circumstance. When an element of fluid is compressed, the work done on it tends to heat it up. If the heat has time to drain away to...
  • adiabatic demagnetization (physics)
    process by which the removal of a magnetic field from certain materials serves to lower their temperature. This procedure, proposed by chemists Peter Debye (1926) and William Francis Giauque (independently, 1927), provides a means for cooling an already cold material (at about 1 K) to a small fraction of 1 K....
  • adiabatic expansion (physics)
    ...be helped by the absorption of certain soluble gases, notably sulfur dioxide to form dilute sulfuric acid. The relative humidity of the air can be increased by three processes: cooling of the air by adiabatic expansion; mixing two humid airstreams having different temperatures; and direct cooling of the air by radiation....
  • adiabatic flow (physics)
    ...is the relevant quantity. If virtually none of the heat escapes, as is more commonly the case in flow problems because the thermal conductivity of most fluids is poor, then the flow is said to be adiabatic, and βS is needed instead. (The S refers to entropy, which remains constant in an adiabatic process provided that it takes place slowly enough to be treated as...
  • adiabatic lapse rate (physics)
    ...such as temperature or density, with increasing altitude) of temperature decreases at a rate greater than 1 °C per 100 metres (approximately 1 °F per 150 feet). This rate is called the adiabatic lapse rate (the rate of temperature change occurring within a rising or descending air parcel). In the ocean, the temperature increase with depth that results in free convection is......
  • adiabatic nuclear demagnetization (physics)
    Much lower temperatures can be attained by an analogous means called adiabatic nuclear demagnetization. This process relies on ordering (aligning) nuclear dipoles (arising from nuclear spins), which are at least 1,000 times smaller than those of atoms. With this process, temperatures of the ordered nuclei as low as 16 microdegrees (0.000016 degree) absolute have been reached....
  • adiabatic process (physics)
    in thermodynamics, change occurring within a system as a result of transfer of energy to or from the system in the form of work only. A rapid expansion or contraction of a gas is very nearly adiabatic. Any process that occurs within a container that is a good thermal insulator is also adiabatic. Adiabatic processes are characterized by an increase in entropy, or degree of disor...
  • adiabatic temperature increase (geophysics)
    ...may be observed to increase slightly with depth. This occurs when the deepest parts of the oceans are filled by water with a single temperature from a common source. This water experiences an adiabatic temperature rise as it sinks. Such a temperature rise does not make the water column unstable because the increased temperature is caused by compression, which increases the density of the......
  • Adiabene (ancient kingdom, Iraq)
    petty kingdom that was a vassal state of the Parthian empire (247 bc–ad 224) in northern Mesopotamia (now Iraq). Its capital was Arba-ilu (Arbela; modern Irbīl). In the 1st century ad its royal family embraced Judaism; the queen mother Helena (d. ad 50), famous for her generosity to the Jews and the Temple, an...
  • Adiantum (plant genus)
    ...and photosynthetic; sperm motile; between 9,000 and 12,000 species; representative genera include Pteridium, Polypodium, Polystichum, Adiantum, and Cyathea.Division Cycadophyta (cycads)Palmlike, gymnospermous plants with typica...
  • Adiantum pedatum (plant)
    ...multilayered (so-called fertile veins). In many ferns all or nearly all of the photosynthesis is accomplished by the epidermis, the mesophyll having been eliminated in evolution. An example is the common maidenhair fern (Adiantum pedatum), the blade of which, between veins, is mainly made up of only two layers, the upper and the lower epidermis, in which most photosynthesis occurs....
  • adiaphorism (Christian theology)
    (from Greek adiaphora, “indifferent”), in Christian theology, the opinion that certain doctrines or practices in morals or religion are matters of indifference because they are neither commanded nor forbidden in the Bible. Two adiaphorist controversies occurred in Germany after the Reformation....
  • Adichie, Chimamanda Ngozi (Nigerian author)
    Nigerian author whose work drew extensively on the Biafran war in Nigeria during the late 1960s....
  • Adidam (religious movement)
    a small religious movement grounded in the Hindu tradition. Founded in 1972 in California by Franklin Jones (born 1939), who changed his name to Adi Da (Sanskrit: “One Who Gives from the Divine Source”) in 1994, it has undergone a number of name changes and considerable internal turmoil....
  • Adiego Lajara, Ignacio (Spanish scholar)
    ...Egyptologist John Ray, who found several grammatical features suggesting that Carian is related to Hittite and Luwian and is part of the Anatolian group. His approach was successfully continued by Ignacio Adiego Lajara and fully confirmed by the discovery of a Carian-Greek bilingual in Kaunos in 1996 and 1997. Much remains uncertain, but the grammatical features thus attested confirm that......
  • Adigal, Ilango, Prince (Tamil author)
    the earliest epic poem in Tamil, written in the 5th–6th century ad by Prince Ilanko Adikal (Ilango Adigal). Its plot is derived from a well-known story....
  • Adige, Fiume (river, Italy)
    longest stream of Italy after the Po River. The Adige rises in the north from two Alpine mountain lakes below Resia Pass and flows rapidly through the Venosta Valley south and east past Merano and Bolzano. Having received the waters of the Isarco River at Bolzano, the Adige turns south to flow through the Trentino-Alto Adige region in its middle course, known as the Lagarina Val...
  • Adige River (river, Italy)
    longest stream of Italy after the Po River. The Adige rises in the north from two Alpine mountain lakes below Resia Pass and flows rapidly through the Venosta Valley south and east past Merano and Bolzano. Having received the waters of the Isarco River at Bolzano, the Adige turns south to flow through the Trentino-Alto Adige region in its middle course, known as the Lagarina Val...
  • Adikal, Ilanko, Prince (Tamil author)
    the earliest epic poem in Tamil, written in the 5th–6th century ad by Prince Ilanko Adikal (Ilango Adigal). Its plot is derived from a well-known story....
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