stoichiometry \,st6i-ke-'a-m9-tre\ Determination of the proportions (by weight or number of molecules) in which elements or compounds react with one another. The rules for determining stoichiometric relationships are based on the laws of conservation (see conservation law) of mass and energy and the law of combining weights (see equivalent weight) or vol¬ umes. The tools used are chemical formulas, chemical equations, atomic weights, and molecular weights or formula weights.
Stoicism Vsto-s-.si-zonA School of philosophy in Greco-Roman antiq¬ uity. Inspired by the teaching of Socrates and Diogenes of Sinope, Stoicism was founded at Athens by Zeno of Citium c. 300 bc and was influential throughout the Greco-Roman world until at least ad 200. It stressed duty and held that, through reason, mankind can come to regard the universe as governed by fate and, despite appearances, as fundamentally rational, and that, in regulating one’s life, one can emulate the grandeur of the calm and order of the universe by learning to accept events with a stem and tranquil mind and to achieve a lofty moral worth. Its teachings have been transmitted to later generations largely through the surviving books of Cicero and the Roman Stoics Seneca, Epictetus, and Marcus Aurelius.
Stoker, Bram orig. Abraham Stoker (b. Nov. 8, 1847, Dublin, Ire.—d. April 20, 1912, London, Eng.) Irish writer. Though bedridden until he was seven years old, Stoker later became an outstanding athlete. He was in the civil service for 10 years and the manager of actor Henry Irving for 27 years, writing letters for his employer and accompanying him on tours. During this period he began writing fiction; his masterpiece was the immensely successful gothic novel Dracula (1897). Derived from vampire legends, the tale became the basis for a whole genre of literature and film. None of his other works, including The Lair of the White Worm (1911), approached its popularity or quality.
Stokes, William (b. Oct. 1, 1804, Dublin, Ire.—d. Jan. 10, 1878, Howth, near Dublin) Irish physician. He received his M.D. from the Uni¬ versity of Edinburgh and returned to Dublin, where he encouraged stu¬ dents to work, under faculty supervision, in hospital wards and to acquire a general as well as a medical education. He succeeded his father as Regius Professor of Physic at the University of Dublin. His publications included A Treatise on the Diagnosis and Treatment of Diseases of the Chest (1837), The Diseases of the Heart and Aorta (1854), and one of the first English works on the stethoscope.
Stokowski, Leopold (Anthony) orig. Antoni Stanislaw Bole- slawawicz Stokowski (b. April 18, 1882, London, Eng.—d. Sept. 13, 1977, Nether Wallop, Hampshire) British-bom U.S. conductor and organist. He studied at the Royal College of Music and the University of Oxford. After holding organist positions and conducting a handful of con¬ certs, he became conductor of the Cincinnati Symphony (1909-12), with great success. From there he moved to the Philadelphia Orchestra, and in the years 1912-38 he made it a world-class ensemble, creating the lush “Philadelphia sound.” He programmed much contemporary music, and he grasped very early the importance of recording. He made three films with the Philadelphia Orchestra, including Walt Disney’s Fantasia (1940), and he used his fame to help foster fledgling music organizations, including the American Symphony Orchestra, which he formed in 1962. His strong advocacy of new music did much to broaden American musical taste.
Stoller, Mike See Jerry Leiber
stolon Vsto-lonV or runner Slender stem that grows horizontally along the ground, giving rise to roots and aerial (vertical) branches at special¬ ized points called nodes. Many annual and perennial grasses have creep¬ ing stolons (e.g., bent grass).
Stolypin \sto-'le-pyin\, Pyotr (Arkadyevich) (b. April 14, 1862, Dresden, Saxony—d. Sept. 18, 1911, Kiev, Ukraine, Russian Empire) Russian politician. Appointed governor of the provinces of Grodno (1902) and Saratov (1903), he improved the welfare of the peasants while also subduing their rebellions. He gained the favour of Tsar Nicholas II and was appointed minister of the interior and prime minister in 1906. He ini¬ tiated agrarian reforms that gave the peasants greater freedom to choose representatives to the zemstvo councils and to acquire land, which he believed would create a loyal and conservative class of farmers. His repressive measures against rebels and terrorists earned him the enmity of liberals. He dissolved the Duma when it opposed his reforms, but he later won support from moderates. He was assassinated by a revolution¬ ary in 1911.
stoma or stomate Any of the microscopic openings or pores in the epidermis of leaves and young stems. They are generally more numerous on the undersides of leaves. They provide for the exchange of gases between the outside air and the interconnecting air canals within the leaf. A stoma opens and closes in response to turgor pressure within its two surrounding guard cells. Because the inner wall of each of these sausage- or bean-shaped cells is thicker than the outer wall, when they fill with water and become turgid they balloon outward, enlarging the stoma. A drop in carbon-dioxide levels to lower than normal also causes the guard cells to become turgid. Guard cells control excessive water loss from the plant, closing on hot, dry, or windy days and opening when conditions are more favorable.
stomach Digestive sac in the left upper abdominal cavity, which expands or contracts with the amount of food in it. It has four regions: the cardia leads down from the esophagus; the fundus curves above it; the body is the largest part; and the antrum narrows to join the duodenum at the pyloric valve. Iron and very fat-soluble substances (e.g., alcohol, some drugs) are absorbed in the stomach. Peristalsis mixes food with enzymes and hydro¬ chloric acid from glands in its lining and moves the resulting chyme toward
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1826 I stomach cancer ► Stonehenge
the small intestine. The vagus nerve and sympathetic nervous system con¬ trol the stomach’s secretions and movements. Emotional stress affects its function. Common disorders include gastritis, peptic ulcer, hiatal hernia, and cancer. See also digestion, gastrectomy.
stomach cancer Malignant tumour of the stomach. The main risk fac¬ tors include a diet high in salted, smoked, or pickled foods; Helicobacter pylori infection; tobacco and alcohol use; age (over age 60); and a family history of stomach cancer. Males develop stomach cancer at approximately twice the rate of females. Symptoms may be abdominal pain or swelling, unexplained weight loss, vomiting, and poor digestion. Surgery is the only method for treating stomach cancer, although radiation therapy or chemo¬ therapy may be used in conjunction with surgery or to relieve symptoms.
stone In building construction, rock cut into blocks and slabs or broken into pieces. It comes as hard as granite and as soft as limestone or sand¬ stone. Where available, stone has generally been the preferred material for monumental structures. Its advantages are durability, adaptability to sculpting, and the fact that it can be used in its natural state. But it is dif¬ ficult to quarry, transport, and cut, and its weakness in tension limits its use. The simplest stonework is rubble, roughly broken stones bound in mortar. Ashlar work consists of regularly cut blocks with squared edges. Building stone is quarried by sawing if it is soft, and split apart with wedges or by blasting if hard. Many devices are used to shape and dress stone, from handheld tools to circular saws, surfacing machines, and lathes. Some stones are strong enough to act as monolithic (one-piece) supports and beams; and in some styles (e.g., ancient Egyptian temples) stone slabs are employed even for roofing, supported by many closely spaced columns. Before the arch, builders were handicapped by the ten¬ dency of stone to break under its own weight. But stone in compression has great strength, and the Romans built huge stone bridges and aque¬ ducts. Though stone has generally been abandoned for structural use in the 20th century, it is widely used as a thin, nonbearing surface cladding. See also masonry.