11 résultats pour "surround"
-
Planetary Science - astronomy.
III ORIGINS AND COMPOSITIONS OF PLANETS Astronomers believe that planetary systems are formed of elemental materials that were created in the interiors of giant stars. Some of this material comes from giantstars that shed material into space as they age. Most of the matter to form planets, however, comes from stars that explode as supernovas and spread debris enrichedwith the heavier chemical elements into space. According to the currently accepted views, the most likely first stage in the evo...
-
Arthur
I
INTRODUCTION
King Arthur
Legend and lore surround the life of Arthur, a medieval king of the Britons.
Arthur Receiving ExcaliburAccording to legend, soon after King Arthur became ruler of Britain, he received his magnificent sword Excalibur from ahand that rose mysteriously from a lake. With Excalibur, Arthur led his armies to many victories over Britain’s enemies.Corbis Because of his humble origins, Arthur must overcome strong opposition from the British nobles to his royal claim, but eventually he is crowned. To help him in his taskof leading Britain, he receives a great sword, Excalibur, off...
-
Arthurian Legend
I
INTRODUCTION
King Arthur
Legend and lore surround the life of Arthur, a medieval king of the Britons.
Merlin and ArthurIn the tales of Arthurian legend, Merlin is an aged magician who helps bring King Arthur to power. Some authors alsodescribe Merlin as the young king’s tutor.Corbis Arthur is conceived when King Uther Pendragon falls in love with a married woman, Ygraine, and arranges for the magician Merlin to transform him into the likeness ofYgraine's husband. The husband, Gorlois, dies in battle, and Arthur's parents marry soon thereafter. Arthur Receiving ExcaliburAccording to legend, soon...
-
Acquired Immunodeficiency Syndrome.
child transmission is particularly prevalent in Africa. D Misperceptions About HIV Transmission The routes of HIV transmission are well documented by scientists, but health officials continually grapple with people’s unfounded fears concerning the potential for HIVtransmission by other means. HIV differs from other infectious viruses in that it dies quickly if exposed to the environment. No evidence has linked HIV transmission tocasual contact with an infected person, such as a handshake, huggi...
-
Astronomy - astronomy.
Telescopes may use either lenses or mirrors to gather visible light, permitting direct observation or photographic recording of distant objects. Those that use lenses arecalled refracting telescopes, since they use the property of refraction, or bending, of light ( see Optics: Reflection and Refraction ). The largest refracting telescope is the 40-in (1-m) telescope at the Yerkes Observatory in Williams Bay, Wisconsin, founded in the late 19th century. Lenses bend different colors of light by d...
-
Shaka.
IV EVALUATION Many powerful myths surround Shaka’s life, making it difficult for people to appraise him rationally. As the founder of the Zulu kingdom—a kingdom whose traditionsand influence survive to this day—Shaka is celebrated for his military prowess, and he serves as a potent symbol of Zulu national pride. For many Europeans, however,he has always epitomized the stereotypical savage African tyrant. Indeed, oral traditions regarding his cruelty have been preserved among the descendants of...
-
Interstellar Matter - astronomy.
silhouette of a cloud of dust. At other times, it blocks only a percentage of the light from behind it, a process known by astronomers as extinction . The long, narrow dark lanes in the Milky Way as seen from Earth are examples of extinction. The amount of extinction is different for different wavelengths of light. A2 Reddening Starlight that does not get completely absorbed by interstellar dust can still be changed by the dust’s effects. As light passes through less dense patches of interstel...
-
Stem Cell.
The medical profession used adult stem cells to treat diseases long before anyone isolated one. In 1968 scientists performed the first successful bone marrowtransplant, a procedure in which a patient receives an infusion of healthy bone marrow cells. The purpose of such transplants is to restore the blood-making capabilitiesof the patient’s diseased bone marrow after extremely strong chemotherapy has destroyed that bone marrow. From the beginning investigators suspected that stemcells in the inf...
-
-
Indian Art and Architecture
I
INTRODUCTION
Art on the Indian Subcontinent
This map highlights places in India and Pakistan where prominent examples of Indian art and architecture have been
produced.
Sun Temple of KonarakThis 13th-century relief depicting a wheel of the chariot of Indian sun god Surya is situated in the Konarak temple. Thetemple, dedicated to Surya, is situated at Puri in the Gulf of Bengal.Keren Su/Corbis The arts of India expressed in architecture, sculpture, painting, jewelry, pottery, metalwork, and textiles, were spread throughout the Far East with the diffusion ofBuddhism and Hinduism and exercised a strong influence on the arts of China, Japan, Myanmar (formerly known...
-
Flower - biology.
insects. The sepals unfurl as the flower opens and often resemble small green leaves at the flower’s base. In some flowers, the sepals are colorful and work with thepetals to attract pollinators. E Variations in Structure Like virtually all forms in nature, flowers display many variations in their structure. Most flowers have all four whorls—pistil, stamens, petals, and sepals. Botanists callthese complete flowers. But some flowers are incomplete, meaning they lack one or more whorls. Incomplet...
-
Cell (biology) - biology.
proteins, or other proteins required by the cell. While relatively simple in construction, prokaryotic cells display extremely complex activity. They have a greater range of biochemical reactions than those found in theirlarger relatives, the eukaryotic cells. The extraordinary biochemical diversity of prokaryotic cells is manifested in the wide-ranging lifestyles of the archaebacteria andthe bacteria, whose habitats include polar ice, deserts, and hydrothermal vents—deep regions of the ocean un...