scientific american - 1998 02 - wrapping up the universe

... well. They were long; the thigh was shorter than the shin, and the fibula, the bone to the side of the shinbone, was re- The Origin of Birds and Their Flight Scientific American February 1998 43 Bones ... bats, the hand part of the wing generates the thrust, and the rest of the wing provides the lift. Jeremy M. V. Rayner of the University of Bristol showed in...

Ngày tải lên: 12/05/2014, 15:33

... of a tiny needle. They also tested the glucose levels in these volunteers by the finger-stick method. They found that both the skin-fluid sample and the fin- ger-stick measured the correct glucose levels ... outside the cell and the other inside. The component outside the cell is the extracellu- lar matrix; the compressive “girders” inside the cell can be ei- ther micr...

Ngày tải lên: 12/05/2014, 15:33

... and applied them to the time-honored tech- nology of fuel cells. The key was in the packaging. Whereas most fuel-cell re- searchers start with the design of the electrolyte and electrodes, Hockaday re- alized ... aperture, the su- perconducting magnet deflects the neg- atively charged electrons in one direc- tion and the positively charged protons and positrons in the other....

Ngày tải lên: 12/05/2014, 15:35

... one of those Tranquilli- ty-base-here -the- Eagle-has-landed, NASA-flight-control jubilation scenes. Laima is the Latvian goddess of good fortune, and the name was a homage to the heritage of Juris ... first time. The heat is daunting. As the after- noon wears on, the debate between Johnson and Fiedel moves first one way, then the other, like a tug-of-war. The debate might never...

Ngày tải lên: 12/05/2014, 15:48

... that the mi- grating bats may not be using their echolocation when the collisions occur. Others spec- ulate that the wind turbines may be emitting high-pitched sounds that draw the bats to the ... within the lu- nar soil. The Arecibo team, headed by Bruce A. Campbell of the Center for Earth and Plane- tary Studies at the Smithsonian Institution, used 70-centimeter-wavelength...

Ngày tải lên: 12/05/2014, 16:19

... the superconduc- tor. There they decorate the regions where the magnet- ic-flux lines pass through the surface. The iron parti- cles “stick” to the surface be- cause of the slight attractive forces ... height of the tubes) across the surface of the sample. The Þeld is largest at the cen- ter of each vortex. The projection be- low the image depicts the vortices as...

Ngày tải lên: 12/05/2014, 14:48

... the wom- en in the rural areas have that same cy- cle, and they teach the same values to their children. They teach their sons to order; they teach their daughters that they must serve even their ... than they do in the laboratory. This so-called redshift is caused by the overall expan- sion of the universe, which reddens, or stretches, the light. The farther away one looks,...

Ngày tải lên: 12/05/2014, 14:49

... aggre- gate. The parts of the receptors that lie inside the cell then assume a distinc- tive enzymatic role: they attach phos- phate groups to themselves and to one another at the sites of the amino ... inter- ests extend beyond Europe. We there- fore need to consider the tanks and other armored forces elsewhere around the world. In the Middle East, Iraq had the most extensi...

Ngày tải lên: 12/05/2014, 14:50

... elliptic curves. Further, these curves would vio- late certain conditions set forth in an- other famous supposition in number theory, the Taniyama-Shimura conjec- ture. In 1986 Kenneth Ribet of the Uni- versity ... cheek-by-snout with people moving into coastal areas pop- ulated with the ani- malsÕ prized food. Ko- alas prefer to eat the leaves of less than a dozen of the 650 na- ti...

Ngày tải lên: 12/05/2014, 15:00

... inhibit candor when they are posed the ques- tion, ÒHow big is the diÝerence?Ó (Fur- ther, the work has not yet been peer-re- viewed or published, so the team re- mains quite cautious about the details.) Essentially ... DNA, the ruthenium-ribose combination revealed something extraordinary. The researchers examined the electri- cal properties of short lengths of dou- ble-helix...

Ngày tải lên: 12/05/2014, 15:01