| | - heart rot
- widespread disease of trees, root crops, and celery. Most trees are susceptible to heart-rotting fungi that produce a discoloured, lightweight, soft, spongy, stringy, crumbly, or powdery heart decay. Conks or ...
- heart sound
- (from the article "human cardiovascular system") Closure of the heart valves is associated with an audible sound, called the heartbeat. The first sound occurs when the mitral and tricuspid valves close, the second when the pulmonary ...
- Heart Sutra
- ("Sutra on the Heart of the Prajnaparamita"), extremely brief distillation of the essence of Prajnaparamita (q.v.; "Perfection of Wisdom") writings, much reproduced and recited throughout Asia. True to its title, ...
- heart transplant
- medical procedure involving the removal of a diseased heart from a patient and its replacement with a healthy heart. Because of the immense complexity of the procedure and the difficulty ... [8 Related Articles]
- heart urchin
- any echinoid marine invertebrate of the order Spatangoidea (phylum Echinodermata), in which the body is usually oval or heart-shaped. The test (internal skeleton) is rather fragile with four porous spaces, ...
- heart valve
- (from the article "cardiovascular disease") ...septum may be small or large and occur most commonly in the midportion in the area prenatally occupied by the aperture called the foramen ovale. Defects lower on the atrial ...
- heart valve stenosis
- (from the article "atresia and stenosis") Aortic, pulmonary, and heart-valve stenoses all cause mild to severe circulatory difficulty in early life but can be repaired by surgery. See also agenesis.
- heart-flowered serapias
- (from the article "Serapias") One species, S. lingua, is commonly known as the tongue orchid. It has a reddish lip, lance-shaped leaves, and a stem up to 30 cm (12 inches) long. The heart-flowered ...
- heart-leaf philodendron
- (from the article "Philodendron") Many forms of philodendron are available in cultivation, foremost among them being the common heart-leaf philodendron (Philodendron scandens oxycardium). The velvet-leaf philodendron (P. scandens micans) has small bronzy-green velvety leaves ...
- heart-lung machine
- (from the article "heart-lung machine") a type of artificial heart (q.v.).types of artificial heartartificial heartHeart-lung machineThe heart-lung
- heart-lung transplant
- (from the article "transplant") ...of the operation, rejection could not be controlled by conventional immunosuppression. With the availability of cyclosporine researchers were able to obtain long-term survivors with combined heart-lung transplants in primate species. ...
- heart-valve atresia
- (from the article "atresia and stenosis") Aortic-arch and heart-valve atresias cause serious difficulty in early life but can sometimes be repaired by surgery.
- heartbeat
- (from the article "heart") The pumping of the heart, or the heartbeat, is caused by alternating contractions and relaxations of the myocardium. These contractions are stimulated by electrical impulses from a natural pacemaker, the ...
- heartburn
- (from the article "nutritional disease") When gastric contents, containing hydrochloric acid, flow backward from the stomach, the lining of the esophagus becomes inflamed, leading to the burning sensation known as heartburn. Occasional heartburn (also known ...
- Heartfield, John
- (from the article "Dada") ...political character. Among the German artists involved were Raoul Hausmann, Hannah Hoch, George Grosz, Johannes Baader, Hulsenbeck, Otto Schmalhausen, and Wieland Herzfelde and his brother John Heartfield (formerly Helmut Herzfelde, ...
- hearth
- (from the article "blast furnace") The bosh is the hottest part of the furnace because of its close proximity to the reaction between air and coke. Molten iron accumulates in the hearth, which has a ...
- hearth group
- (from the article "Australian Aborigine") ...a daily basis). Flexible in size and composition, it was the land-utilizing group, highly mobile and able to respond quickly to altered ecological and social circumstances. The individual family, or ...
- Hearths, Cave of
- (from the article "South Africa") ...An archaic form of H. sapiens appeared about 500,000 years ago; important specimens belonging to this physical type have been found at Hopefield in Western Cape province and at the ...
- heartland
- landlocked region of central Eurasia whose control was posited by Sir Halford J. Mackinder in the early 20th century as the key to world domination in an era of declining ... [1 Related Articles]
- hearts
- card game in which players aim to avoid taking tricks that contain hearts. Hearts first appeared in the United States about 1880, although it derives from the much older European ...
- heartwood
- dead, central wood of trees. Its cells usually contain tannins or other substances that make it dark in colour and sometimes aromatic. Heartwood is mechanically strong, resistant to decay, and ... [4 Related Articles]
- heartworm
- (from the article "filariasis") ...nematodes of the superfamily Filarioidea, that invade the subcutaneous tissues and lymphatics of mammals, producing reactions varying from acute inflammation to chronic scarring. In the form of heartworm, it may ...
- heartworm disease
- parasitic disease, predominantly of dogs but also occurring in cats, that is caused by the nematode Dirofilaria immitis. Infective larvae (microfilariae) develop in mosquitoes, which serve as ...
- heat
- energy that is transferred from one body to another as the result of a difference in temperature. If two bodies at different temperatures are brought together, energy is transferred-i.e., heat ... [54 Related Articles]
- heat adaptation
- (from the article "climatic adaptation") Heat adaptation is of two types: adaptation to humid heat and to dry heat (desert conditions). In hot climates the problem is not in maintaining body heat but in dissipating ...
- heat bleaching
- (from the article "fat and oil processing") ...the resistance of oils to rancidity, because some natural antioxidants are removed together with impurities. When many oils are heated to more than 175° C (347° F), a phenomenon known ...
- heat budget
- (from the article "atmosphere") The primary driving force for the horizontal structure of Earth's atmosphere is the amount and distribution of solar radiation that comes in contact with the planet. Earth's orbit around the ...
- heat capacity
- ratio of heat absorbed by a material to the temperature change. It is usually expressed as calories per degree in terms of the actual amount of material being considered, most ... [6 Related Articles]
- heat cramps
- (from the article "cramp") ...which involve contractions of the uterine muscle, occur before or during menstruation and may last from several hours to a day. They occur most commonly in younger women who have ...
- heat death
- (from the article "physical science, principles of") It is possible, however, that in the course of time the universe will suffer "heat death," having attained a condition of maximum entropy, after which tiny fluctuations are all that ...
- heat engine
- (from the article "thermodynamics") The classic example of a heat engine is a steam engine, although all modern engines follow the same principles. Steam engines operate in a cyclic fashion, with the piston moving ...
- heat exchanger
- any of several devices that transfer heat from a hot to a cold fluid. In many engineering applications it is desirable to increase the temperature of one fluid while cooling ... [2 Related Articles]
- heat exhaustion
- (from the article "heatstroke") ...difficulties. Without sufficient water, they may suffer from dehydration and may collapse from inadequate circulation. This collapse, whether caused by dehydration or other phenomena, is called heat exhaustion, or heat ...
- heat flux
- (from the article "rock") Heat flow (or flux), q, in the Earth's crust or in rock as a building material, is the product of the temperature gradient (change in temperature per unit distance) and ...
- heat island
- (from the article "urban climate") ...at related urban and rural sites frequently show that the urban site is 6° to 11° C (10° to 20° F) warmer than the rural site. Two primary processes influence ...
- heat of combustion
- (from the article "reaction, heat of") ...not even be feasible, it is customary to estimate heats of reactions from suitable combinations of compiled standard thermal data. These data usually take the form of standard heats of ...
- heat of formation
- (from the article "reaction, heat of") ...to estimate heats of reactions from suitable combinations of compiled standard thermal data. These data usually take the form of standard heats of formation and heats of combustion. The standard ...
- heat of fusion
- (from the article "carbon group element") ...elements, irrespective of size, is uniformly bonded throughout, and, therefore, the whole fragment can be considered as a giant molecule. Decreasing melting points, boiling points, and decreasing heat energies associated ...
- heat of sublimation
- (from the article "carbon group element") ...bonded throughout, and, therefore, the whole fragment can be considered as a giant molecule. Decreasing melting points, boiling points, and decreasing heat energies associated with fusion (melting), sublimation (change from ...
- heat of vaporization
- (from the article "carbon group element") ...fragment can be considered as a giant molecule. Decreasing melting points, boiling points, and decreasing heat energies associated with fusion (melting), sublimation (change from solid to gas), and vaporization (change ...
- heat pipe
- form of heat exchanger (q.v.) useful for transporting heat over relatively large distances with a small temperature difference.
- heat pump
- device for transferring heat from a substance or space at one temperature to another substance or space at a higher temperature. It consists of a compressor, a condenser, a throttle ... [3 Related Articles]
- heat rate
- (from the article "turbine") The performance of a steam turbine is conventionally measured in terms of its heat rate-i.e., the amount of heat that has to be supplied to the feedwater in order to ...
- heat ring
- (from the article "meat processing") Heat ring is a problem associated with beef carcasses and results from differential chilling rates of the muscles after slaughter. A heat ring is a dark, coarsely textured band around ...
- heat sink
- (from the article "thermoelectric power generator") ...thermoelectric power generators have the same basic configuration, as shown in the figure. A heat source provides the high temperature, and the heat flows through a thermoelectric converter to a ...
- heat summation
- (from the article "wine") ...when average daily temperature is about 10° C (50° F). To reach maturity, they require a certain amount of heat above 10° C during the growing season. This amount of ...
- heat transfer
- any or all of several kinds of phenomena, considered as mechanisms, that convey energy and entropy from one location to another. The specific mechanisms are usually referred to as convection, ... [15 Related Articles]
- heat transfer printing
- (from the article "textile") The popularity of polyester fabrics has led to the development of a completely new form of printing termed heat transfer printing, which prints the pattern on paper with carefully selected ...
- heat treatment
- (from the article "fish processing") Heat treatment can significantly alter the quality and nutritional value of fish. Fish is exposed to heat during both the cooking process and the canning process.foodstuffs
- heat wave
- (from the article "summer") A period of exceptionally hot weather, often with high humidity, during the summer is called a heat wave. Such an occurrence in the temperate regions of the Northern Hemisphere in ...
- heat-mirror glass
- (from the article "building construction") ...tinted glass that would absorb and reduce solar gain, and in the 1960s reflective glass with thin metallic coatings applied by the vacuum plating process was introduced, also to reduce ...
- heat-seeking missile
- (from the article "rocket and missile system") ...nor received commands from an external source; rather, they "locked" onto an electronic emission coming from the target itself. The earliest successful passive homing munitions were "heat-seeking" air-to-air missiles that ...
- heat-sensitive device
- (from the article "sprinkler system") ...or building untouched by fire, an improvement was sought and found in the Parmelee sprinkler head, introduced in the United States in the 1870s. In this, the normally closed orifice ...
- heat-sensitive organ
- (from the article "rattlesnake") Rattlesnakes are pit vipers (subfamily Crotalinae of the family Viperidae), a group named for the small heat-sensing pit between each eye and nostril that aids in hunting. The pits provide ...
- heat-setting
- (from the article "textile") ...removed, the weave is straightened, and the fabric is dried to its final size. When the process is applied to wet wools it is called crabbing; when applied to synthetic ...
- heath
- any of the low evergreen shrubs of the genus Erica, of the family Ericaceae, with about 500 species, most of which are indigenous to South Africa, where they are especially ... [3 Related Articles]
- heath banksia
- (from the article "scrubland") ...conditions necessary for reproduction and are unable to regenerate without appropriate intervals of burning. For example, a common and attractive shrub of coastal scrublands in eastern Australia, Banksia ericifolia, is ...
- Heath, James
- (from the article "bath chair") chair on wheels intended for use by ladies and invalids. It was devised by James Heath, of Bath, Eng., about 1750. For the next three-quarters of a century it rivaled ...
- Heath, Percy Leroy
- American musician (b. April 30, 1923, Wilmington, N.C.- d. April 28, 2005, Southampton, N.Y.), became renowned for his melodic bass playing in the Modern Jazz Quartet (MJQ), one of the ... [1 Related Articles]
- Heath, Sir Edward
- Conservative prime minister of Great Britain from 1970 to 1974. [6 Related Articles]
- Heath, Thomas
- (from the article "Thales' rectangle") Although none of Thales' original proofs survives, the English mathematician Thomas Heath (1861-1940) proposed what is now known as Thales' rectangle (see the figure) as a proof ...
- Heathcliff
- (from the article "Baird, Bil and Cora") A few of their creations became classic puppet figures: Bubbles La Rue, the marionette striptease dancer; the singing frogs; Snarky Parker, the master of ceremonies; and Heathcliff, the talking horse. ...
- Heathcoat, John
- pioneering English inventor of lace-making machinery.
- Heathcot machine
- (from the article "textile") ...early models required intricate engineering mechanisms, and the development of the modern lace industry originated when a machine was designed to produce laces identical with Brussels lace. In the Heathcot, ...
- Heathcote, J. J.
- (from the article "tennis") ...since it distinguished the court from ordinary rectangular courts. At the time, the Marylebone Cricket Club (MCC) was the governing body of real tennis, whose rules it had recently revised. ...
- heathenism
- (from the article "United Kingdom") Place-names containing the names of gods or other heathen elements are plentiful enough to prove the vitality of heathenism and to account for the slow progress of conversion in some ...
- heather
- (species Calluna vulgaris), low evergreen shrub of the heath family (Ericaceae), widespread in western Europe and Asia, North America, and Greenland. It is the chief vegetation on many wastelands of ... [3 Related Articles]
- Heather-Latu, Brenda
- (from the article "Samoa") ...Malielegaoi quickly promoted some young ministers to key positions in the cabinet. The election was followed by a number of petitions from unsuccessful candidates, and in August Attorney General Brenda ...
- Heathrow Airport
- (from the article "Hillingdon") ...between World Wars I and II. During the Battle of Britain (1940-41), Uxbridge was the site of an underground control centre that directed British air defenses. London's largest airport, Heathrow, ...
- heating
- process and system of raising the temperature of an enclosed space for the primary purpose of ensuring the comfort of the occupants. By regulating the ambient temperature, heating also serves ... [7 Related Articles]
- Heatley, Dany
- (from the article "Ice Hockey") The IIHF men's victory gave Canada its 23rd world title, equaling the total amassed by the Soviet Union/Russia. Team Canada's Dany Heatley, a forward for the NHL Atlanta Thrashers, led ...
- Heatley, Norman George
- British biochemist (b. Jan. 10, 1911, Woodbridge, Suffolk, Eng.-d. Jan. 5, 2004, Oxford, Eng.), devised a way to isolate penicillin from its substrate and measure its activity and was instrumental ...
- Heaton, John
- (from the article "Olympic Games") ...(headfirst) sledding, which had not been held at the 1932 or 1936 Games, was revived for the 1948 Games but discontinued thereafter until the 2002 Winter Olympics because of the ...
- heatstroke
- condition caused by continuous exposure to high temperature and humidity for several hours. The term sunstroke refers to the same disorder when exposure to direct sunlight is the main cause ... [1 Related Articles]
- heave
- (from the article "ship") ...sway (sideways motion). More generally, motions are possible in all six degrees of freedom, the other four being roll (rotation about a longitudinal axis), pitch (rotation about a transverse axis), ...
- heaven
- in many religions, the abode of God or the gods, as well as of angels, deified humans, the blessed dead, and other celestial beings. It is often conceived as an ... [13 Related Articles]
- Heaven's Gate
- religious group founded in the United States on a belief in unidentified flying objects. Under a variety of names over the years, including Human Individual Metamorphosis, Bo and Peep, and ... [2 Related Articles]
- Heaven, Temple of
- (from the article "Beijing") Among the historical and religious structures in Beijing, the Temple of Heaven (Tiantan), located south of the palace compound in the old outer city, is unique both for its unusual ...
- heavenly blue morning glory
- (from the article "Ipomoea") ...Jalap (I. purga) is an upright herb with solitary, reddish flowers, native in tropical Mexico. Its apple-sized, turnip-shaped roots are the source of an ancient purgative, still in use. Heavenly ...
- Heavenly Purity, Palace of
- (from the article "Beijing") ...last hall, the Hall of Preserving Harmony (Baohedian), after which comes the Inner Court (Neiting). The Inner Court was used as the emperor's personal apartment. It contains three large halls, ...
- Heavens
- (from the article "Divine, Father") In 1933 Father Divine and his followers left Sayville for Harlem, where he became one of the most flamboyant leaders of the Depression era. There he opened the first of ...
- heaves
- chronic disorder of the lungs of horses and cows, characterized by difficult breathing and wheezy cough. The symptoms are worsened by vigorous exercise, sudden weather changes, and overfeeding. Heaves resulting ...
- heavier-than-air aircraft
- (from the article "airplane") Heavier-than-air craft: early history
aviationaviationthe development and operation of heavier-than-air aircraft. The term "civil aviation" refers to the air-transportation service provided ...
- heavily cratered terrain
- (from the article "Mercury") ...larger craters are relatively flat, less-cratered regions termed intercrater plains. These are similar to but much more pervasive than the light-coloured plains that occupy intercrater areas on the heavily cratered ...
- Heavily Indebted Poor Countries Initiative
- (from the article "Sao Tome and Principe") ...for the bonanza promised by the discovery of oil in its offshore waters, it was rewarded for its good governance and stable economy by the IMF, which offered debt relief ...
- Heaviside, Oliver
- physicist who predicted the existence of the ionosphere, an electrically conductive layer in the upper atmosphere that reflects radio waves. In 1870 he became a telegrapher, but increasing deafness forced ... [6 Related Articles]
- heavy aircraft
- (from the article "aerospace industry") The need for large-scale air transportation has been central to commercial aircraft manufacturing. As one of the world's most vital industries, airlines are key to many aspects of the world ...
- heavy artillery
- (from the article "tactics") To overcome a well-entrenched enemy was something that could be achieved, if at all, only by tremendous concentrations of heavy artillery. Directed by forward observers and from balloons and aircraft ...
- heavy cavalry
- (from the article "tactics") The next development following chariots was cavalry, which took two forms. From Mongolia to Persia and Anatolia-and, later, on the North American plains as well-nomadic peoples fought principally with missile ...
- heavy coal slurry
- (from the article "coal mining") ...coal and a liquid such as water or oil. The traditional mixture, first patented in England in 1891, consists of 50 percent coal and 50 percent water by weight. So-called ...
- heavy component
- (from the article "liquid") ...alcohol, and at 125.7° C for octane. In a liquid solution, the component with the higher vapour pressure is called the light component, and that with the lower vapour pressure ...
- heavy element
- (from the article "Milky Way Galaxy") ...giant stars in globular clusters have chemical abundances quite different from those of Population I stars such as typified by the Sun. Population II stars have considerably lower abundances of ...
- heavy ground
- (from the article "tunnels and underground excavations") The miner's term for very weak or high geostress ground that causes repeated failures and replacement of support is heavy ground. Ingenuity, patience, and large increases of time and funds ...
- heavy industry
- (from the article "Table III. Pattern of Output, 1989-92") Secondary industry may be divided into heavy, or large-scale, and light, or small-scale, industry. Large-scale industry generally requires heavy capital investment in plants and machinery, serves a large and diverse ...
- heavy infantry
- (from the article "tactics") ...emerged shortly after 1000 BC. Reliefs from great Assyrian palaces show horsemen, clad in armour and armed with spear or lance, who were used in combination with other troops such ...
- heavy ion
- in nuclear physics, any particle with one or more units of electric charge and a mass exceeding that of the helium-4 nucleus (alpha particle). Special types of accelerators are capable ... [1 Related Articles]
- Heavy Ion Research, Institute for
- (from the article "hassium") an artificially produced element belonging to the transuranium group, atomic number 108. It was synthesized and identified in 1984 by West German researchers at the Institute for Heavy Ion Research ...
- heavy machine gun
- (from the article "machine gun") ...of its military unit. The medium machine gun, or general-purpose machine gun, is belt-fed, mounted on a bipod or tripod, and fires full-power rifle ammunition. Through World War II the ...
- heavy metal
- genre of rock music that includes a group of related styles that are intense, virtuosic, and powerful. Driven by the aggressive sounds of the distorted electric guitar, heavy metal is ... [7 Related Articles]
- heavy oil and tar sand
- crude oils below 20° API gravity are usually considered to be heavy. The lighter conventional crudes are often waterflooded to enhance recovery. The injection of water into the reservoir helps ... [3 Related Articles]
- heavy particle
- (from the article "radiation measurement") The term heavy charged particle refers to those energetic particles whose mass is one atomic mass unit or greater. This category includes alpha particles, together with protons, deuterons, fission fragments, ...
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