Encyclopædia Britannica Australia -

Encyclopedias since 1768

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radiology ... Rahner, Karl

radiology: branch of medicine using radiation for the diagnosis and treatment of disease. Radiology originally involved the use of X rays in the diagnosis of disease and the use of X rays, gamma rays, and other forms of ionizing radiation in ...
radiometer: instrument for detecting or measuring radiant energy. The term is applied in particular to devices used to measure infrared radiation. Radiometers are of various types that differ in their method of measurement or detection. Those that function by means of ...
radiosonde: balloon-borne instrument for making atmospheric measurements, such as temperature, pressure, and humidity, and radioing the information back to a ground station. Special helium-filled meteorological balloons made of high-quality neoprene rubber are employed for elevating the radiosonde to very high altitudes ...
radiotelegraphy: radio communication by means of Morse Code or other coded signals. The radio carrier is modulated by changing its amplitude, frequency, or phase in accordance with the Morse dot-dash system or some other code. At the receiver the coded modulation ...
radish: (Raphanus sativus), annual or biennial plant in the family Brassicaceae that is grown for its large, succulent root. The edible part of the root, together with some of the seedling stem, forms a structure varying in shape, among varieties, from ...
Radishchev, Aleksandr Nikolayevich: writer who founded the revolutionary tradition in Russian literature and thought.
Radisson, Pierre Esprit: French explorer and fur trader who served both France and England in Canada.
radium: radioactive chemical element, heaviest of the alkaline-earth metals of main Group IIa of the periodic table. Radium is a silvery white metal that does not occur free in nature.
radius: in anatomy, the outer of two bones of the forearm when viewed with the palm facing forward. All land vertebrates have this bone. In humans it is shorter than the other bone of the forearm, the ulna.
Radke, Lina: German athlete who set several middle-distance running records between 1927 and 1930. Her victory in the 800-metre race at the 1928 Olympic Games-the first Olympics to include women's athletics-set a world record that was not broken for 16 years.
Radlov, Vasily: German scholar and government adviser who made fundamental contributions to the knowledge of the ethnography, folklore, culture, ancient texts, and linguistics of the Turkic peoples of Southern Siberia and Central Asia.
Radnorshire: historic county, east-central Wales, on the English border. It covers an area of mountainous terrain and highlands, including Radnor Forest, with a central valley formed by the River Wye. Radnorshire lies completely within the present county of Powys.
Radom: city, Mazowieckie wojewodztwo (province), east-central Poland. It is a rail junction and an administrative and industrial centre; the economy of the city relies predominantly on textile milling, glass- and chemical works, munitions and footwear manufacturing, and food ...
radon: (Rn), chemical element, a heavy radioactive gas of Group 0 (noble gases) of the periodic table, generated by the radioactive decay of radium. Radon is a colourless, odourless, tasteless gas, 7.5 times heavier than air and more than 100 times ...
Radowitz, Joseph Maria von: conservative Prussian diplomat and general who was the first statesman to attempt the unification of Germany under Prussian hegemony (from 1847), anticipating Otto von Bismarck's more successful efforts by almost 20 years.
radula: horny, ribbonlike structure found in the mouths of all mollusks except the bivalves. The radula, part of the odontophore, may be protruded, and it is used in drilling or in rasping food particles from a surface. It is supported by ...
Radziwill Family: an important Polish-Lithuanian princely family that played a significant role in Polish-Lithuanian history.
Rae Bareli: town, administrative headquarters of Rae Bareli district, Uttar Pradesh state, northern India, southeast of Lucknow, on the Sai River. Named for the Bhar people, it is a road and rail junction and an agricultural trade centre. Industries include the milling ...
Rae, John: Scottish-born American economist, physician, and teacher.
Rae, John: physician and explorer of the Canadian Arctic.
Raeburn, Sir Henry: leading Scottish portrait painter during the late 18th and early 19th centuries.
Raeder, Erich: commander in chief of the German Navy (1928-43) and proponent of an aggressive naval strategy, who was convicted as a war criminal for his role in World War II.
Raedwald: also spelled Redwald king of the East Angles in England from the late 6th or early 7th century, son of Tytili.
Raemaekers, Louis: Dutch cartoonist who gained international fame with his anti-German cartoons during World War I.
Raetia: ancient Roman province comprising Vorarlberg and Tirol states in present-day Austria, the eastern cantons of Switzerland, and parts of Bavaria and Baden-Wurttemberg states in Germany. Its native inhabitants were probably of mixed Illyrian and Celtic stock. The area was conquered ...
Raetian language: language spoken by the ancient Raetians in southern Germany and in the Alpine regions of Italy, Austria, and Switzerland in pre-Roman times. The language is known from a number of inscriptions.
Raff, Joachim: German composer and teacher, greatly celebrated in his lifetime but nearly forgotten in the late 20th century.
Raffi: celebrated Armenian novelist.
Raffles, Sir Stamford: British East Indian administrator and founder of the port city of Singapore (1819), who was largely responsible for the creation of Britain's Far Eastern empire. He was knighted in 1816.
Rafflesiales: order of flowering plants constituting three families (Rafflesiaceae, Mitrastemonaceae, and Hydnoraceae) and up to 60 species, although Mitrastemonaceae is not included in some classifications. The order is notable for being strictly parasitic upon the roots or stems of other plants ...
Rafidah: (Arabic: "Rejectors"), broadly, Shi'ite Muslims who reject (rafd) the caliphate of Muhammad's two successors Abu Bakr and 'Umar. Many Muslim scholars, however, have stated that the term Rafidah cannot be applied to the Shi'ites in general but only to the ...
Rafinesque, Constantine Samuel: naturalist, traveler, and writer who made major and controversial contributions to botany and ichthyology.
Rafsanjani, Hashemi: Iranian cleric and politician, who was president of Iran from 1989 to 1997.
raft: simplest type of watercraft, made up of logs or planks fastened together to form a floating platform. The earliest were sometimes made of bundles of reeds. Most rafts have been designed simply to float with the current, but they can ...
RAG Aktiengesellschaft: German company that was created in order to consolidate all coal-mining activities in the Ruhr region. Company headquarters are in Essen.
rag worm: any of a group of mostly marine or shore worms of the class Polychaeta (phylum Annelida). A few species live in fresh water. Other common names include mussel worm, pileworm, and sandworm. Rag worms vary in length from 2.5 to ...
raga: ("colour," or "passion"), in the music of India and Pakistan, a melodic framework for improvisation based on a given set of notes (usually five to seven) and characteristic rhythmic patterns. The basic components of a raga can be written down ...
ragfish: (genus Icosteus aenigmaticus), marine fish, the single species in the family Icosteidae (order Perciformes). The ragfish is found throughout the North Pacific. The name refers to their floppy, limp bodies, which are considered flexible as a rag.
ragged school: any of the 19th-century English and Scottish institutions maintained through charity and fostering various educational and other services for poor children, such as elementary schooling, industrial training, religious instruction, clothing clubs, and messenger and bootblack brigades. The schools were allied ...
Raghunatha Siromani: philosopher and logician who brought the New Nyaya school, representing the final development of Indian formal logic, to its zenith of analytic power.
Raglan, FitzRoy James Henry Somerset, 1st Baron: field marshal, first British commander in chief during the Crimean War. His leadership in the war has usually been criticized.
Ragnar Lothbrok: Viking whose life passed into legend in medieval European literature.
Ragnarok: (Old Norse: "Doom of the Gods"), in Scandinavian mythology, the end of the world of gods and men. The Ragnarok is fully described only in the Icelandic poem Voluspa ("Sibyl's Prophecy"), probably of the late 10th century, and in the ...
ragtime: propulsively syncopated musical style, one forerunner of jazz and the predominant style of American popular music from about 1899 to 1917. Ragtime evolved in the playing of honky-tonk pianists along the Mississippi and Missouri rivers in the last decades of ...
Ragunan Zoological Gardens: zoo in Jakarta, Indon., that is one of the world's notable collections of Southeast Asian flora and fauna. More than 3,500 specimens of approximately 450 animal species are exhibited on the 200-hectare (494-acre) park grounds. Among these are the orangutan, ...
Ragusa: city, capital of Ragusa provincia, southeastern Sicily, Italy. The city lies in the Hyblaei Hills above the gorge of the Irminio River, west of Syracuse. The old lower town of Ragusa Ibla (on the site of the ancient Hybla Heraea) ...
ragweed: (genus Ambrosia), any of a group of about 15 species of weedy plants of the family Asteraceae. Most species are native to North America. The ragweeds are coarse annuals with rough hairy stems, mostly lobed or divided leaves, and inconspicuous ...
rahbaniyah: (Arabic: "monasticism"), the monastic state, whose admissibility in Islam is much disputed by Muslim theologians. The term appears but once in the Qur'an: "And we set in the hearts of those who follow Jesus, tenderness and mercy. And monasticism they ...
Rahimyar Khan: town, southern Punjab province, Pakistan. The town was founded in 1751 as Naushehra and received its present name in 1881. It is linked by road and rail with Bahawalpur, Multan, and Sukkur and is a growing industrial centre (cotton ginning ...
Rahman, Mujibur: Bengali leader and first prime minister (1972-75) and later president (1975) of Bangladesh.
Rahner, Karl: German Jesuit priest who is widely considered to have been one of the foremost Roman Catholic theologians of the 20th century. He is best known for his work in Christology and for his integration of an existential philosophy of personalism ...