P.V. Sindhu is a professional badminton player from India who has made her mark in the 21st century with a number of wins at the Commonwealth Games, the Badminton World Federation (BWF) Championships, and the Olympic Games. She is the first Indian woman to win two Olympic medals—a silver medal at

small arm: Minié rifles: 702-inch Pattern 1851 Minié rifle. In the Crimean War (1854–56), Russian troops armed with smoothbore muskets were no match for Britons shooting P/51 rifles. Massed formations were easy prey, as were cavalry and artillery units. A correspondent for the Times of London wrote: “The Minié is…

Encke’s Comet, faint comet having the shortest orbital period (about 3.3 years) of any known; it was also only the second comet (after Halley’s) to have its period established. The comet was first observed in 1786 by French astronomer Pierre Méchain. In 1819 German astronomer Johann Franz Encke

Halley’s Comet, the first comet whose return was predicted and, almost three centuries later, the first to be imaged up close by interplanetary spacecraft. In 1705 English astronomer Edmond Halley published the first catalog of the orbits of 24 comets. His calculations showed that comets observed

powder metallurgy, fabrication of metal objects from a powder rather than casting from molten metal or forging at softening temperatures. In some cases the powder method is more economical, as in fashioning small metal parts such as gears for small machines, in which casting would involve

Comet Schwassmann-Wachmann 1, short-period comet discovered photographically by the German astronomers Friedrich Karl Arnold Schwassmann and Arno Arthur Wachmann on November 15, 1927. It has one of the most circular orbits of any comet known (eccentricity = 0.044) and remains always between the

Pluto: Pluto’s moons: Pluto’s other four moons—Hydra, Nix, Kerberos, and Styx—are much smaller than Charon. All four are elongated. They revolve around Pluto outside Charon’s path in nearly circular orbits (like Charon) and in the same orbital plane as Charon. The orbital radius of Hydra is about 64,721 km (40,216 miles);…

P blood group system: …substances known as the P, P1, and Pk antigens on the surfaces of red blood cells. These antigens are also expressed on the surfaces of cells lining the urinary tract, where they have been identified as adhesion sites for Escherichia coli bacteria, which

Pluto: Pluto’s moons: Nix, Kerberos, and Styx—are much smaller than Charon. All four are elongated. They revolve around Pluto outside Charon’s path in nearly circular orbits (like Charon) and in the same orbital plane as Charon. The orbital radius of Hydra is about 64,721 km (40,216 miles); that…

P2P, type of computer network often used for the distribution of digital media files. In a peer-to-peer (P2P) network, each computer acts as both a server and a client—supplying and receiving files—with bandwidth and processing distributed among all members of the network. Such a decentralized

Hassan Rouhani: Presidency and nuclear agreement: …Kingdom (known collectively as the P5+1). By the end of the month, an interim agreement had been reached that eased sanctions on Iran and placed a variety of restrictions on the nuclear program. A final agreement, known as the Joint Comprehensive Plan of Action (JCPOA), was reached in July 2015…

cell cycle: …mutations in a protein called p53, which normally detects abnormalities in DNA at the G1 checkpoint, can enable cancer-causing mutations to bypass this checkpoint and allow the cell to escape apoptosis.

tumour suppressor gene: …tumour suppressor genes (such as TP53, which encodes a protein known as p53) have been identified. The mutated form of TP53 has been implicated in more than 50 percent of all cancers. Mutations in two other tumour suppressor genes, BRCA1 and BRCA2, are associated with an increased susceptiblity to breast…

protactinium (Pa), radioactive chemical element of the actinoid series of the periodic table, rarer than radium; its atomic number is 91. It occurs in all uranium ores to the extent of 0.34 part per million of uranium. Its existence was predicted by Russian chemist Dmitry Mendeleyev in his 1871

Māori: Māori versus Pākehā: …generally successful sieges of Māori pās (fortified villages) by British troops and militia. The British were defeated during an attack (June 1860) on Puketakauere pā when the Māori executed a surprise counterattack, but the Māori were defeated at Ōrongomai in October and Maahoetahi in November. The war ended in a…

Ba, ancient tribe and later an ancient Chinese feudal state that came into being in the 11th century bce, under the Xi (Western) Zhou dynasty. It was situated in the Jialing valley of present-day eastern Sichuan and Chongqing municipality. Ba established relations with the mid-Yangtze kingdom of

pascal (Pa), unit of pressure and stress in the metre-kilogram-second system (the International System of Units [SI]). It was named in honour of the French mathematician-physicist Blaise Pascal (1623–62). A pascal is a pressure of one newton per square metre, or, in SI base units, one kilogram per

Palestinian Authority (PA), governing body of the Palestinian autonomous regions of the West Bank and Gaza Strip established in 1994 as part of the Oslo Accords peace agreement between Israel and the Palestine Liberation Organization (PLO) (see two-state solution). Following years of hostility,

Ba Jin was a Chinese anarchist writer whose novels and short stories achieved widespread popularity in the 1930s and ’40s. Having been born to a wealthy gentry family, Li Yaotang received a traditional Confucian education as well as training in modern foreign languages and literatures. While in

Baxian, heterogeneous group of holy Daoists, each of whom earned the right to immortality and had free access to the Peach Festival of Xiwangmu, Queen Mother of the West. Though unacquainted in real life, the eight are frequently depicted as a group—bearing gifts, for instance, to Shouxing, god of

Baren was a Chinese prose writer and critic who was the first Chinese literary theorist to promote the Marxist point of view. After graduating from primary school, Wang entered the Fourth Normal School in Ningpo. In 1920 Wang completed his studies and began his career as a teacher. His interest in

Lao literature: Modern Lao literature: …Lao literature, history, and culture: Pakian Viravong, Duangdeuan Viravong, and Dara Viravong (pseudonyms Pa Nai, Dauk Ket, and Duang Champa, respectively). An equally important writer was Outhine Bounyavong, Maha Sila Viravong’s son-in-law, who remained a notable writer through the turn of the 21st century; his short stories were translated into…

Pa Sak River, river in central Thailand. It rises in the northern portion of the Phetchabun Range and flows south through a narrow valley for 319 miles (513 km). It empties into the Lop Buri River at the city of Ayutthaya, north of Bangkok. Lomsak, Phetchabun, and Sara Buri are the main towns on

Amalie Skram: …from 1895, Professor Hieronimus and På St. Jørgen (“At St. Jorgen’s”), in which she gives an artistically controlled but thinly veiled description of her own treatment for a nervous disorder at a mental institution in Copenhagen. English translations of both novels were published in one volume, Under Observation (1992).

Olympic Games: Stockholm, Sweden, 1912: Electronic timing devices and a public address system were used for the first time. The Games were attended by approximately 2,400 athletes representing 28 countries. New competition included the modern pentathlon and swimming and diving events for women. The boxing competition was canceled by the Swedish organizers, who found the…

Pa-an, town, southern Myanmar (Burma). Situated on the left bank of the Salween River, 27 miles (43 km) north of Mawlamyine (Moulmein), it has an airfield and is linked by road west to Thaton and across the Dwana Range to Thailand. Pop. (2006 est.)

Banner system, the military organization used by the Manchu tribes of Manchuria (now Northeast China) to conquer and control China in the 17th century. The Banner system was developed by the Manchu leader Nurhachi (1559–1626), who in 1601 organized his warriors into four companies of 300 men each.

pottery: China: The bagua, consisting of eight sets of three lines, broken and unbroken in different combinations, represent natural forces. They are often seen in conjunction with the yin-yang symbol, which represents the female-male principle, and which has been well described by the pottery scholar R.L. Hobson as…

Chang-hua: The Pa-kua (Bagua) Mountains, a western extension of the Chung-yang (Zhongyang) Range, are in the southeast. The rest of the region is a fertile alluvial deltaic plain.

Everglades, subtropical saw-grass marsh region, a “river of grass” up to 50 miles (80 km) wide but generally less than 1 foot (0.3 metre) deep, covering more than 4,300 square miles (11,100 square km) of southern Florida, U.S. Through it, water moves slowly southward to mangrove swamps bordering

Black River, one of the chief tributaries of the Red River (Song Hong) in southeastern Asia. Nearly 500 miles (800 km) long, the river rises in central Yunnan province in southwestern China and flows southeastward into northwestern Vietnam on a course parallel to the Red River. Near the city of Hoa

Amitabh Bachchan: …his performance in the drama Paa (2009), playing a boy who suffers from an aging disease similar to progeria.

Knut Hamsun: …with Paa gjengrodde stier (On Overgrown Paths), which was in part memoir, in part self-defense, but first and foremost a treasure trove of vibrant impressions of nature and the seasons. His deliberate irrationalism and his wayward, spontaneous, impressionistic style had wide influence throughout Europe, and such writers as Maxim…

skiing: Skiing grows in popularity: …developed after the publication of The First Crossing of Greenland (Paa ski over Grønland; 1890), Fridtjof Nansen’s account of his 1888–89 trans-Greenland expedition on skis.

Svante Pääbo is a Swedish evolutionary geneticist who specialized in the study of DNA from ancient specimens and who was the first to contribute to the sequencing of the Neanderthal genome. Pääbo also discovered the hominin Denisova. For his groundbreaking research on hominin genomes and human

Tom Kristensen: …of technological achievements; the second, Paafuglefjeren (1922; “The Peacock Feather”), expresses his love of exotic-sounding names and brilliant colours and was inspired by a journey to China and Japan in 1922. A later volume of poetry, Den sidste lygte (1954; “The Last Lantern”), is meditative and philosophical. Hærværk (1930; Havoc),…

Paamiut, town, southwestern Greenland, on the Atlantic coast at the mouth of 30-miles- (48-km-) long Kvanefjord and south-southeast of Frederikshåbs Isblink (ice field), a navigation landmark. It was founded in 1742. After World War II it was chosen to be a model of modernization and a major centre

paan, an Indian after-dinner treat that consists of a betel leaf (Piper betle) filled with chopped betel (areca) nut (Areca catechu) and slaked lime (chuna; calcium hydroxide), to which assorted other ingredients, including red katha paste (made from the khair tree [Acacia catechu]) may be added.

betel, either of two different plants whose leaves and seeds are used in combination for chewing purposes throughout wide areas of southern Asia and the East Indies. The betel nut is the seed of the areca, or betel, palm (Areca catechu), family Arecaceae, and the betel leaf is from the betel

Naseeruddin Shah: …Film Festival for Goutam Ghose’s Paar (1984). For his contributions to Indian cinema, Shah was given the Padma Shri (1987) and the Padma Bhushan (2003), two of India’s highest civilian awards. His autobiography, And Then One Day, was published in 2014.

postal system: Growth of the post as a government monopoly: Some, like the Paar family in Austria, developed postal organizations on a national scale. By far the most famous and extensive of such systems was that built up by the Thurn and Taxis family, who originally came from Bergamo near Milan, Italy. Under the patronage of the Habsburg…

Jack Paar was an American humorist who, as host (1957–62) of The Tonight Show (later called The Jack Paar Show), was one of the pioneers of late night television. Paar quit school when he was 16 years old and went to work first as a radio announcer and later as a comic and disc jockey on a series

Jack Paar was an American humorist who, as host (1957–62) of The Tonight Show (later called The Jack Paar Show), was one of the pioneers of late night television. Paar quit school when he was 16 years old and went to work first as a radio announcer and later as a comic and disc jockey on a series

Paarl, town, Western Cape province, South Africa, east of Cape Town, on the Groot-Berg River between the Paarl Mountain and the Drakenstein Range. Settled in 1688 by Huguenots, who introduced viticulture, it is still known for its vineyards and wine making; it also produces citrus fruits, tobacco,

Paasche index, index developed by German economist Hermann Paasche for measuring current price or quantity levels relative to those of a selected base period. It differs from the Laspeyres index in that it uses current-period weighting. The index is a ratio that compares the total purchase cost of

Paasche index: …index developed by German economist Hermann Paasche for measuring current price or quantity levels relative to those of a selected base period. It differs from the Laspeyres index in that it uses current-period weighting.

Juho Kusti Paasikivi was a Finnish statesman and diplomat who, as prime minister (1918, 1944–46) and then president (1946–56) of Finland, cultivated harmonious relations with the Soviet Union in an effort to ensure some measure of independence for Finland. Paasikivi studied law and history at the

Rafael Paasio was a Finnish typographer, journalist, and politician who served as prime minister of Finland (1966–68, 1972). Paasio was editor in chief (1938–63) of three Social Democratic party newspapers, notably Turun Päivälehti 1952–63), and a member of the municipal council of Turku from 1945.

Rafael Paasio was a Finnish typographer, journalist, and politician who served as prime minister of Finland (1966–68, 1972). Paasio was editor in chief (1938–63) of three Social Democratic party newspapers, notably Turun Päivälehti 1952–63), and a member of the municipal council of Turku from 1945.

New Zealand literature: Maori narrative: the oral tradition: …or to assist the chanter), paatere (chants by women in rebuttal of gossip or slander, asserting the performer’s high lineage and threatening her detractors), kaioraora (expressions of hatred and abuse of an enemy, promising terrible revenge), and the haka (a chant accompanied by rhythmic movements, stamping, and fierce gestures, the…

Finland: Drainage and soils: In the extreme north the Paats River and its tributaries drain large areas into the Arctic. On Finland’s western coast a series of rivers flow into the Gulf of Bothnia. These include the Tornio, which forms part of Finland’s border with Sweden, and the Kemi, which, at 343 miles (550…

football: South America: In Paraguay, Dutchman William Paats introduced the game at a school where he taught physical education, but the country’s first (and still leading) club, Olimpia, was formed by a local man who became enthusiastic after seeing the game in Buenos Aires in 1902. In Bolivia the first footballers…

bustard: …South Africa are known as paauw, the largest being the great paauw or kori bustard (Ardeotis kori). The Arabian bustard (A. arabs) is found in Morocco and in northern tropical Africa south of the Sahara, as are a number of species belonging to several other genera. In Australia the bustard…

One of the so-called Flying Finns who long dominated distance running, Paavo Nurmi was perhaps the greatest runner of them all. Legend has it that his training regimen included racing a mail train in his hometown of Turku, Finland. Nurmi, of course, frequently outran the train, fueling the

The biggest triumph of Paavo Yrjölä, a four-time Olympian, came at the 1928 Games in Amsterdam. Yrjölä, a native of Finland, had competed in the decathlon in the 1920 Olympic Games in Antwerp, Belgium, and 1924 Games in Paris, although he had not earned a medal. As he prepared for another shot at

Finnish literature: The early 20th century: …Torchbearers’ leaders was the essayist Olavi Paavolainen, a brilliant travel writer and analyst of the times, who in Kolmannen valtakunnan vieraana (1939; “As a Guest in the Third Reich”) expressed prophetic alarm at—but also his fascination with—the developments in Adolf Hitler’s Germany. Paavolainen’s last published work was a war diary,…

para-aminobenzoic acid (PABA), a vitamin-like substance and a growth factor required by several types of microorganisms. In bacteria, PABA is used in the synthesis of the vitamin folic acid. The drug sulfanilamide is effective in treating some bacterial diseases because it prevents the bacterial

pabbajjā, Buddhist rite of ordination by which a layman becomes a novice (Pāli sāmaṇera; Sanskrit śrāmaṇera). The ceremony is also the preliminary part of higher ordination, raising a novice to a monk (see upasaṃpadā). In some Theravāda countries such as Burma, the rite is normally held for every

Pabianice, town and suburb of Łódź, in Łódzkie województwo (province), central Poland, in the Łódź Highlands on the Dobrzynka River. The second most important town in the surrounding industrial area, it lies on the Łódź-Wrocław rail line and is a major textile centre. The oldest community in the

Radiohead: Although its debut album, Pablo Honey (1993), barely hinted at the grandeur to come, the startling single “Creep”—a grungy snarl of self-loathing—made major waves in the United States.

John Rechy: …the Blue Hour (2017), and Pablo! (2018). In addition, he published the essay collection Beneath the Skin (2004). About My Life and the Kept Woman (2008) is a memoir.

Fourth International: …Fourth International’s leadership fell to Michel Pablo and Ernest Germain, two Belgian Trotskyists. When in 1949 Pablo predicted “degenerated workers’ states for centuries” and, consequently, called for the dissolution of the International, a factional fight erupted, culminating in 1953 in the Fourth International’s split into two factions—the International Committee and…

history of publishing: Other continental printers: …over one of his men, Juan Pablos. In that year, Pablos published the first printed book in the New World, Doctrina christiana en la lengua mexicana e castellana (“Christian Doctrine in the Mexican and Castilian Language”).

Pabna, city, west-central Bangladesh. It lies along the Ichamati River, which is a tributary of the upper Padma River (Ganges [Ganga] River). An industrial centre, Pabna has mills for jute, cotton, rice, flour, oil, paper, and sugar. It also produces pharmaceuticals. Hosiery and hand-loomed

Milwaukee: The contemporary city: The Captain Frederick Pabst Mansion (1892), a 37-room home built by one of the city’s early major brewers, offers tours.

G.W. Pabst was a German film director whose films were among the most artistically successful of the 1920s. Pabst’s films are marked by social and political concerns, deep psychological insight, memorable female protagonists, and human conflicts with culture and society. He is also noted for his

G.W. Pabst was a German film director whose films were among the most artistically successful of the 1920s. Pabst’s films are marked by social and political concerns, deep psychological insight, memorable female protagonists, and human conflicts with culture and society. He is also noted for his

materials science: Photoresist films: A photoresist typically contains a photoactive compound (PAC) and an alkaline-soluble resin. The PAC, mixed into the resin, renders it insoluble. This mixture is coated onto the semiconductor wafer and is then exposed to radiation through a “mask” that carries the desired pattern. Exposed PAC is converted into an acid…

political action committee (PAC), in U.S. politics, an organization whose purpose is to raise and distribute campaign funds to candidates seeking political office. PACs are generally formed by corporations, labour unions, trade associations, or other organizations or individuals and channel the

Pan-Africanist Congress of Azania (PAC), South African organization and later political party pursuing “Africanist” policies in South Africa (which they would rename Azania) for black South Africans, in contrast to the nonracial or multiracial policies of other organizations, such as the African

Pac-12, West Coast American collegiate athletic association that grew out of several earlier versions, the first of which, the Pacific Coast Conference (PCC), was founded in 1915. The Pac-12 shrank to two schools in 2024. The original members of the PCC were the University of California (Berkeley),

Pac-12, West Coast American collegiate athletic association that grew out of several earlier versions, the first of which, the Pacific Coast Conference (PCC), was founded in 1915. The Pac-12 shrank to two schools in 2024. The original members of the PCC were the University of California (Berkeley),

In 1980 the Japanese arcade game manufacturer Namco Limited introduced the world to Pac-Man. The lead designer was Iwatani Tohru, who intended to create a game that did not emphasize violence. By paying careful attention to themes, design, and colours, Iwatani hoped that Namco could market an

Manny Pacquiao is a professional boxer, media celebrity, and politician who became world-famous for winning boxing titles in more weight classes than any other boxer in history. His rise from abject poverty to the pinnacle of his sport was made even more remarkable by his life outside the ring. The

Pac-Man: In 1980 the Japanese arcade game manufacturer Namco Limited introduced the world to Pac-Man. The lead designer was Iwatani Tohru, who intended to create a game that did not emphasize violence. By paying careful attention to themes, design, and colours, Iwatani hoped that Namco could…

paca: The paca (Cuniculus paca) is found from eastern Mexico to northern Argentina and northern Uruguay, living in tropical forests at elevations ranging from sea level to 3,000 metres (9,800 feet). It weighs 5 to 13 kg (11 to 29 pounds) and has a body length of…

paca, (genus Cuniculus), either of two species of South American rodents with piglike bodies, large heads, and swollen cheeks. They have short ears, large eyes, and long whiskers, and their bodies are stout, with large rumps and short limbs. The front feet have four toes, and the hindfeet have

Bolivia: Languages and religion: …Altiplano, especially the worship of Pachamama, the goddess of the Earth. Also worshiped is the sun god, legendary creator of the first Inca emperor Manco Capac and his sister-wife Mama Ocllo on the Island of the Sun in Lake Titicaca. Through the centuries, the Roman Catholic Church has accepted some…

Pacaraima Mountains, central tabular upland of the Guiana Highlands in Brazil, Venezuela, and Guyana. The Pacaraima Mountains form the drainage divide between the Orinoco Valley to the north and the Amazon Basin to the south. Extending for 250 miles (400 km) in an east–west direction, the mountains

pacarana, (Dinomys branickii), a rare and slow-moving South American rodent found only in tropical forests of the western Amazon River basin and adjacent foothills of the Andes Mountains from northwestern Venezuela and Colombia to western Bolivia. It has a chunky body and is large for a rodent,

Pacasmayo, seaport town, northwestern Peru. It lies near the mouth of the Jequetepeque River. The surrounding valley is an agricultural oasis for growing sugarcane and rice. A railroad constructed in the 1870s connected Pacasmayo to Chilete but closed in 1967 during construction of the Pan-American

Latinius Pacatus Drepanius was a Gallo-Roman orator and poet, the author of an extant panegyric addressed to Theodosius I at Rome in 389 after the defeat of the usurper Maximus. He was a friend of Symmachus, the champion of paganism, and of the Christian poet Ausonius. It is uncertain whether

Latinius Pacatus Drepanius was a Gallo-Roman orator and poet, the author of an extant panegyric addressed to Theodosius I at Rome in 389 after the defeat of the usurper Maximus. He was a friend of Symmachus, the champion of paganism, and of the Christian poet Ausonius. It is uncertain whether

South Asian arts: The kathakali school: (1) Pachcha (“green”) is the noble hero whose face is painted bright green and framed in a white bow-shaped sweep from ears to chin. Heroes such as Rama, Lakshmana, Krishna, Arjuna, and Yudhishthira fall into this category. (2) Katti (“knife”), haughty and arrogant but learned and…

Mont Blanc: …was conquered in 1786 by Michel-Gabriel Paccard, a doctor from Chamonix, together with Jacques Balmat, his porter. Paccard’s achievement, one of the most important in the history of mountaineering, was overshadowed by de Saussure’s ascent the year after. Through Marc-Théodore Bourrit, who failed the ascent and, out of jealousy, published…

Inca: History: …originated in the village of Paqari-tampu, about 15 miles (24 km) south of Cuzco. The founder of the Inca dynasty, Manco Capac (Manqo Qhapaq), led the tribe to settle in Cuzco, which remained thereafter their capital. Until the reign of the fourth emperor, Mayta Capac (Mayta Qhapaq), in the 14th…

pratyaya, in Buddhist philosophy, an auxiliary, indirect cause, as distinguished from a direct cause (hetu). A seed, for example, is a direct cause of a plant, while sunshine, water, and earth are auxiliary causes of a plant. Sometimes pratyaya means the cause in general. According to the 4th- or

pratyeka-buddha, in Buddhism, one who attains enlightenment through his own efforts, as distinct from one who reaches the goal by listening to the teachings of a buddha. The pratyeka-buddha, who is not omniscient and cannot enlighten others, is to be distinguished from the “complete buddha”

Monster of Florence: In 1994 Pietro Pacciani, an itinerant farm labourer, was convicted of murdering seven of the eight couples. Pacciani’s conviction was overturned, however, and a new trial was ordered. Police then began to suspect that the crimes had been committed by a group led by Pacciani, but he…

camel: Natural history: …the camel’s gait is a pace, with both legs on a side moving together. Short bursts of 65 km (40 miles) per hour are possible, but camels are excellent plodders. Bactrian camels can carry more than 200 kg (about 440 pounds) for 50 km (31 miles) in a day, while…

measurement system: Greeks and Romans: Five Roman feet made the pace (passus), equivalent to 1.48 metres or 4.86 feet.

Pace University, private, coeducational institution of higher learning with campuses in New York City, Pleasantville, and White Plains, New York, U.S. The university includes Dyson College of Arts and Sciences, Lubin School of Business, Lienhard School of Nursing, and schools of Education, Law, and

Pace University, private, coeducational institution of higher learning with campuses in New York City, Pleasantville, and White Plains, New York, U.S. The university includes Dyson College of Arts and Sciences, Lubin School of Business, Lienhard School of Nursing, and schools of Education, Law, and

race records: …short-lived Black Swan label of Harry Pace is recognized as the first. Pace’s motto was “The only genuine colored record. Others are only passing for colored.” African American artists who recorded for Black Swan included Alberta Hunter, Ethel Waters, and pianist and bandleader Fletcher Henderson. When Pace sold the label…

mosaic: Renaissance to modern mosaics: …the works of the Venetian Luigi da Pace after Raphael’s cartoon, in the dome of the Chigi Chapel in Santa Maria del Popolo in Rome (1516), and the mosaics made after the cartoons of Titian, Tintoretto, Giuseppe Salviati, and Paolo Veronese to complete the decoration of St. Mark’s in Venice.…

Pius XII was the pope, bishop of Rome and head of the Roman Catholic Church, who had a long, tumultuous, and controversial pontificate (1939–58). During his reign as pope, the papacy confronted the ravages of World War II (1939–45), the abuses of the Nazi, fascist, and Soviet regimes, the horror of

Saint John XXIII: Reign as pope: His major encyclical, Pacem in Terris (“Peace on Earth”), addressed to all humankind, was received warmly throughout the world and praised by politicians as well as churchmen. Straightforward and frankly optimistic, it avoided the language of diplomacy and set forth the requirements for world peace in profoundly human…

nervous system: Diffuse nervous systems: Finally, pacemaker systems are present in animals with nerve nets. In the sea anemone Metridium these systems are expressed in a series of spontaneous rhythmic movements that occur in the absence of any detectable stimulus. It is not known whether the movements originate from a “command”…

pacemaker, electronic cardiac-support device that produces rhythmic electrical impulses that take over the regulation of the heartbeat in patients with certain types of heart disease. A healthy human heart contains its own electrical conducting system capable of controlling both the rate and the

metabolism: Fine control: …the synthesis of key (pacemaker) enzymes. It was recognized in the 1950s, largely from work with microorganisms, that pacemaker enzymes can interact with small molecules at more than one site on the surface of the enzyme molecule. The reaction between an enzyme and its substrate—defined as the compound with…