Narcotics are drugs that relieve pain, often induce sleep, and refer to opium, opium derivatives, and synthetic substitutes. Natural narcotics include opium (paregoric, parepectolin), morphine (MS-Contin, Roxanol), codeine (Tylenol with codeine, Empirin with codeine, Robitussan AC), and thebaine. Semisynthetic narcotics include heroin (horse, smack), and hydromorphone (Dilaudid). Synthetic narcotics include meperidine or Pethidine (Demerol, Mepergan), methadone (Dolophine, Methadose), and others (Darvon, Lomotil). Opium is the milky exudate of the incised, unripe seedpod of the opium poppy. Opium poppy (Papaver somniferum) is the source for many natural and semisynthetic narcotics. Poppy straw concentrate is the alkaloid derived from the mature dried opium poppy. Qat (kat, khat) is a stimulant from the buds or leaves of catha edulis that is chewed or drunk as tea. Stimulants are drugs that relieve mild depression, increase energy and activity, and include cocaine (coke, snow, crack), amphetamines (Desoxyn, Dexedrine), phenmetrazine (Preludin), methylphenidate (Ritalin), and others (Cylert, Sanorex, Tenuate). Infant mortality rate: The number of deaths to infants under one year old in a given year per l,000 live births occurring in the same year. International disputes: This category includes a wide variety of situations that range from traditional bilateral boundary disputes to unilateral claims of one sort or another. Information regarding disputes over international boundaries and maritime boundaries has been reviewed by the Department of State. References to other situations involving borders or frontiers may also be included, such as resource disputes, geopolitical questions, or irredentist issues. However, inclusion does not necessarily constitute official acceptance or recognition by the US Government. Irrigated land: The figure refers to the land area that is artificially supplied with water. Land use: Human use of the land surface is categorized as arable land--land cultivated for crops that are replanted after each harvest (wheat, maize, rice); permanent crops--land cultivated for crops that are not replanted after each harvest (citrus, coffee, rubber); meadows and pastures--land permanently used for herbaceous forage crops; forest and woodland--under dense or open stands of trees; and other--any land type not specifically mentioned above (urban areas, roads, desert). Leaders: The chief of state is the titular leader of the country who represents the state at official and ceremonial functions but is not involved with the day- to-day activities of the government. The head of government is the administrative leader who manages the day-to-day activities of the government. In the UK, the monarch is the chief of state, and the Prime Minister is the head of government. In the US, the President is both the chief of state and the head of government.