Interstate Commerce Commission (ICC) (1887-1995) First regu¬ latory agency established in the U.S. and a prototype for independent government regulatory bodies. An agency of the U.S. Department of Transportation, it was responsible for the economic regulation of inter¬ state surface transportation, including railroads, trucking companies, and buslines. It certified carriers, regulated rates, oversaw mergers, and approved railroad construction. The ICC was dissolved in 1995.
interstellar medium Content of the region between the stars, includ¬ ing vast, diffuse clouds of gases and minute solid particles. Such tenuous matter in the Milky Way Galaxy accounts for about 5% of its total mass. By no means a complete vacuum, the interstellar medium contains mainly hydrogen gas, with a smaller amount of helium and sizable quantities of dust particles of uncertain composition. Primary cosmic rays also travel through interstellar space, and magnetic fields extend across much of it. Most interstellar matter occurs in cloudlike concentrations, which can condense to form stars. Stars, in turn, continually lose mass through stel¬ lar winds (see solar wind). Supernovas and planetary NEBULAe also feed mass back to the interstellar medium, where it mixes with matter that has not yet formed stars (see Populations I and II).
interval In music, the inclusive distance between one tone and another, whether sounded successively (melodic interval) or simultaneously (har¬ monic interval). In Western music, intervals are generally named accord¬ ing to the number of scale-steps within a given key that they embrace;
thus, the ascent from C to G (C-D-E-F-G) is called a fifth because the interval embraces five scale degrees. There are four perfect intervals: prime, or unison; octave; fourth; and fifth. The other intervals (seconds, thirds, sixths, sevenths) have major and minor forms that differ in size by a half step (semitone). Both perfect and major intervals may be aug¬ mented, or enlarged by a half tone. Perfect and minor intervals may be diminished, or narrowed by a half tone.
oo A-° -e-” ^ -o-^ ^ -o-
unison | third | fifth | seventh |
second fourth sixth octave
Examples of simple musical intervals.
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intestate succession In the law of inheritance, transmission of prop¬ erty or property interests of a decedent as provided by statute, as distin¬ guished from transfer according to the decedent’s will. Modern laws of intestacy, though they vary widely, share the common principle that the estate should devolve upon persons standing in some kinship relation with the decedent; modern practice tends to favour the rights of the surviving spouse.
intestinal gas Volatile material (mostly swallowed air, partly digestive by-products) in the digestive tract, which normally contains 150-500 cc of gas. Air in the stomach is either belched out or passed to the intestines. Some of its oxygen is absorbed into the blood along the way. Carbon dioxide produced by digestion is added. Nitrogen, the major component, is inert and usually passed on. Obstructions in the small intestine can trap gas in distended pockets, causing severe pain. In the large intestine, bac¬ terial fermentation products are added—mostly hydrogen but also meth¬ ane, hydrogen sulfide, ammonia, and sulfur-containing mercaptans. Excess gas in the colon is eventually expelled from the body.
intestinal obstruction Blockage of the small intestine or large intes¬ tine, resulting from either lack of peristalsis or mechanical obstruction (e.g., by narrowing, foreign objects, or HERNIA). Obstruction near the start of the small intestine often causes vomiting. Near the end or in the large intes¬ tine, backed-up waste and swallowed air cause intestinal distention; the resulting pressure may cause necrosis (death of intestinal wall tissue). Waste products may escape into the bloodstream. Symptoms and treat¬ ment depend on the obstruction’s nature and location.
intestine See large intestine, small intestine
intifadah \,in-ti-'fa-d3\ Arabic "shaking off" Palestinian revolt (1987-93, 2000- ) against the Israeli occupation in the Gaza Strip and West Bank. Initially a spontaneous reaction to 20 years of occupation and worsening economic conditions, it was soon taken over by the Palestine Liberation Organization (PLO). Its tactics included strikes, boycotts, and confrontations with Israeli troops. The International Red Cross estimated that some 800 Palestinians, more than 200 under the age of 16, had been killed by Israeli security forces by 1990. Several dozen Israelis were killed during the same period. Intifadah pressure is credited with helping make possible the 1993 Israeli-PLO agreement on Palestinian self-rule. A break¬ down in further negotiations in late 2000 led to another outburst of vio¬ lence, which quickly became known as the Aqsa intifadah, named for the Aqsa Mosque in Jerusalem, where the fighting began. See also Yasir 'Arafat; Fatah; Hamas.
Intolerable Acts or Coercive Acts (1774) Four punitive measures enacted by the British Parliament against the American colonies. Boston’s harbour was closed until restitution was made for the tea destroyed in the Boston Tea Party; the Massachusetts colony’s charter was annulled and a military governor installed; British officials charged with capital offenses could go to England for trial; and arrangement for housing British troops in American houses was revived. The Quebec Act added to these oppres¬ sive measures. The acts, called “intolerable” by the colonists, led to a convening of the Continental Congress.
intonation In phonetics, the melodic pattern of an utterance. Intonation is primarily a matter of variation in the pitch level of the voice (see tone), but in languages such as English, stress and rhythm are also involved. Intonation conveys differences of expressive meaning (e.g., surprise.
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introvert and extravert ► investment bank I 953
doubtfulness). In many languages, including English, intonation serves a grammatical function, distinguishing one type of phrase or sentence from another. Thus, “it’s gone” is an assertion when spoken with a drop in pitch at the end, but a question when spoken with a rise in pitch at the end.
introvert and extravert Basic personality types, according to the theories of Carl Gustav Jung. The introvert, who directs thoughts and feelings inward, is often shy, contemplative, and reserved. The extravert, who directs attention toward other people and the outside world, is usu¬ ally outgoing, responsive, and aggressive. This typology is now regarded as simplistic because almost no one can be described as wholly introverted or extraverted.
intrusive rock Igneous rock formed from magma forced into older rocks at depths within the Earth’s crust, which then slowly solidifies below the Earth’s surface, though it may later be exposed by erosion. Igneous intru¬ sions form a variety of rock types. See also extrusive rock.
intuition In philosophy, the power of obtaining knowledge that is not or cannot be acquired either by inference or observation. As such, intu¬ ition is thought of as an original, independent source of knowledge, since it is designed to account for just those kinds of knowledge that other sources do not provide. Knowledge of some necessary truths and basic moral principles is sometimes explained in this way. A technical sense of intuition, deriving from Immanuel Kant, refers to immediate acquaintance with individual entities; intuition ( Anschauung ) in this sense may be empirical (e.g., consciousness of sense-data) or pure (e.g., consciousness of space and time a priori as forms of all empirical intuitions). As con¬ ceived by Benedict de Spinoza and Henri Bergson, intuition is taken to be concrete knowledge of the world as an interconnected whole, as con¬ trasted with the piecemeal, “abstract” knowledge obtained by science and observation.