7 résultats pour "mapping"

• Mapping génétique

  par son deuxième chromosome (le chromosome normal annihilant l'autre). Mais le passage chez un enfant mâle du même chromosome porteur de l'un de ces gènes don­ nera un individu atteint de l'infirmité . 4 A l'opposé des cellules banales (somatiques), qui en possèdent toutes deux jeux, spermatozoïdes et ovules ne contiennent qu'un seul jeu de chromosomes. Ce phéno­ mène propre aux glandes sexuelles s'appelle la méiose. Au cours de la méiose, le...

• Geology.

  terminology. Today the geologic time scale is generally agreed upon and used by scientists around the world, dividing time into eons, eras, periods, and epochs. Everyfew years, the numerical time scale is refined based on new evidence, and geologists publish an update. Geologists use several methods to determine geologic time. These methods include physical stratigraphy, or the placement of events in the order of their occurrence,and biostratigraphy, which uses fossils to determine geologic time...

• Space Exploration - astronomy.

  to produce 250,000 newtons (56,000 lb) of thrust. The Germans launched thousands of V-2s carrying explosives against targets in Britain and The Netherlands. Whilethey did not prove to be an effective weapon, V-2s did become the first human-made objects to reach altitudes above 80 km (50 mi)—the height at which outer spaceis considered to begin—before falling back to Earth. The V-2 inaugurated the era of modern rocketry. A2 Early Artificial Satellites During the years following World War II, the...

• Mercury (planet) - astronomy.

  In 1991 powerful radio telescopes on Earth revealed signs of possible deposits of ice in the polar regions of Mercury. These ice deposits occur in areas where sunlightnever falls, such as crater bottoms near both of the planet’s poles. Similar ice deposits may have been found during the 1990s near the poles of the Moon by theClementine and Lunar Prospector spacecrafts. The ice on Mercury likely comes from comets or water-bearing meteorites that have hit Mercury over the planet’s historyup throug...

• Captain James Cook.

  After leaving Tahiti, the expedition headed north into uncharted territory. After becoming the first Europeans to sight the Hawaiian Islands (which Cook named theSandwich Islands) in 1778, they sailed along the west coast of Canada and Alaska. Twice Cook explored inlets that offered some promise of a Northwest Passage, but tono avail. After sailing through the Bering Strait into the Arctic Sea and briefly scouting the Asian side of the strait, Cook decided to winter in the Hawaiian Islands. Hein...

• Captain James Cook - explorer.

  After leaving Tahiti, the expedition headed north into uncharted territory. After becoming the first Europeans to sight the Hawaiian Islands (which Cook named theSandwich Islands) in 1778, they sailed along the west coast of Canada and Alaska. Twice Cook explored inlets that offered some promise of a Northwest Passage, but tono avail. After sailing through the Bering Strait into the Arctic Sea and briefly scouting the Asian side of the strait, Cook decided to winter in the Hawaiian Islands. Hein...

• Space Shuttle - astronomy.

  The two SRBs, with their combined thrust of some 26 million newtons (about 5.8 million lb), provide most of the power for the first two minutes of flight. The SRBs takethe space shuttle to an altitude of 45 km (28 mi) and a speed of 4,973 km/h (3,094 mph) before they separate and fall back into the ocean to be retrieved,refurbished, and prepared for another flight. After the boosters fall away, the three main engines continue to provide thrust. These engines are clustered at the rear end of the...