Sunday, February 29, 2004

Rio Grande

Spanish  Río Grande del Norte,  or (in Mexico)  Río Bravo,  or  Río Bravo del Norte,   fifth longest river of North America, and the 20th longest in the world, forming the border between the U.S. state of Texas and Mexico. Rising as a clear, snow-fed mountain stream more than 12,000 feet (3,700 metres) above sea level in the Rocky Mountains, the Rio Grande descends across steppes and deserts, watering rich agricultural regions as it flows on its way to the Gulf of Mexico. The

Saturday, February 28, 2004

Mammal, Reproductive system

The testes of mammals descend from the abdominal cavity to lie in a compartmented pouch termed the scrotum. In some species the testes are permanently scrotal and the scrotum is sealed off from the general abdominal cavity. In others the testes migrate to the scrotum only during the breeding season. It is thought that the temperature of the abdominal cavity is too

Thursday, February 26, 2004

Pigweed

Any of several coarse annual plants of cosmopolitan distribution that are often troublesome weeds. Several of them belong to the genus Amaranthus, of the family Amaranthaceae. Prostrate pigweed, or mat amaranth (A. graecizans), grows along the ground surface with stems rising at the tips; spiny pigweed, or spiny amaranth (A. spinosus), has spines at the base of the leafstalks;

Monday, February 23, 2004

Tinkisso River

River, rising in the southern outliers of the Fouta Djallon mountains of Guinea, northeast of Mamou. It flows 250 miles (400 km) north-northeast and east, past Dabola and Bissikrima, across grassy plains and savannas of stunted trees, to enter the Niger River just south of Siguiri. Alluvial gold deposits have long been worked along the Tinkisso River.

Sunday, February 22, 2004

Liquid

In physics, one of the three principal states of matter, intermediate between gas and crystalline solid.

Thursday, February 19, 2004

Mammal, Locomotion

Specialization in habitat preference has been accompanied by locomotor adaptations. Terrestrial mammals have a number of modes of progression. The primitive mammalian stock was doubtless ambulatory and plantigrade, walking with the digits, metacarpals, and metatarsals (bones of the midfoot), and parts of the ankle and wrist in contact with the ground. The limbs

Wednesday, February 18, 2004

Gir Range

Low mountain range in western Gujarat state, west-central India, on the southern Kathiawar Peninsula. The range is extremely rugged with a steep slope seaward to the south and a gradual slope inland to the north. From it to the north runs a low, narrow, dissected range rising to Gorakhnath (3,665 feet [1,117 m], believed to be an extinct volcano) in the broad mass of the Girnar Hills. The Gir Range

Sunday, February 15, 2004

Beryl

Mineral composed of beryllium aluminum silicate, Be3Al2(SiO3)6, a commercial source of beryllium. It has long been of interest because several varieties are valued as gemstones. These are aquamarine (pale blue-green); emerald (deep green); heliodor (golden yellow); and morganite (pink). Beryl is a minor constituent of many granitic rocks and associated pegmatite dikes, in gneisses,

Saturday, February 14, 2004

E-commerce

Although in the vernacular e-commerce usually refers only to the trading of goods and services over the Internet, broader economic activity is included. E-commerce consists of business-to-consumer and business-to-business

Wednesday, February 11, 2004

Star

Any massive, self-luminous celestial body of gas that shines by radiation derived from its internal energy sources. Of the trillions of stars comprising the universe, only a very small percentage are visible to the naked eye. Many stars occur in pairs, multiple systems, and clusters. The members of such stellar groups are physically related through common origin