scientific american - 1998 01 - flying over the solar system

... of a tiny needle. They also tested the glucose levels in these volunteers by the finger-stick method. They found thatboth the skin-fluid sample and the fin-ger-stick measured the correct glucoselevels ... 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 microtubules or large bundles of cross-linked ... are the com-pression struts, and muscles, tendons and ligaments are the tension-bearing members. At the other end of the scale, pro-teins and other key molecules in the body also stabilize them-selves...

scientific american - 1998 02 - wrapping up the universe

... 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 43Bones of ContentionAlthough ... 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 the late 1970s that the down-and-forward ... and ca-ble television companies. The govern-ment tolerated monopolies as long as itcould regulate them, and justifying themas natural somehow made them accept-able in a free-enterprise system. ...

scientific american - 1998 11 - greenland's mysterious meteor - fire over the ice

... Scotland rees-tablished contact with the craft about25 hours after they last heard from it,they reenacted one of those Tranquilli-ty-base-here -the- Eagle-has-landed,NASA-flight-control jubilation ... (photo-graph at right). Near the center of the glow, where the solar reflection ismost intense, the slicks look espe-cially bright. But at the periphery of the sun-glint pattern, the slicks ap-pear ... rocket. The National Aero-nautics and Space Ad-ministration has consid-ered them for space sci-ence. The Departmentof Defense is interestedin them for use in bal-listic-missile intercep-tors;...

scientific american - 1993 01 - the turbulent birth of the milky way

... declines as the reefs get farther awayfrom two centersÑone in the Indo-Pa-ciÞc and the other in the Caribbean. The outlines of a map marking plum-meting diversity coincide with the con-tours ... around the world in the latitudes that general-ly fall between the southern tip of Flori-da and mid-Australia. They rank among the most biologically productive of allmarine ecosystems. Because they ... bleaching, environ-mental tolerances and the life-his-tory characteristics of the domi-nant corals determine whether a reef re-covers from the loss of most of its livingcoral. So do the nature...

91
1,075
0

scientific american - 1996 01 - the diet - aging connection

... like the one about the Ro-man galley slaves who get extra foodrations because the captain wants togo waterskiing:¥ According to the air force, the phaseout cut the use of ozone-bust-ing CFC-113 ... OGDENCopyright 1995 Scientific American, Inc. SCIENTIFIC AMERICAN January 1996 31easily destroyed. Moreover, some theo-rists raised certain technical objec-tions, namely, that the release of a pho-ton ... transform their experiment into the quantum eraser, the researcherstagged one of the photons of the pair(speciÞcally, the one created by the la-serÕs direct passage through the crys-tal). That...

scientific american - 1998 04 - the unwired world

... andapplied 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 ... in-fects more than 95 percent of the motor neurons in the spinal cordand many other cells in the brain. The infected cells either overcome the virus or die. The extent of paralysis is unpre-dictable. ... 21BEHIND -THE- KNEE LIGHT PADSwere used to manipulate the biological clocks of volunteers.INSTITUTE FOR CIRCADIAN PHYSIOLOGY Copyright 1998 Scientific American, Inc.Copyright 1998 Scientific American, ...

scientific american - 2002 01 - the first human clone

... of the objections. For the mo-ment, then, the theory is ingenious mathe-matics—but of the type that has a long histo-ry of ultimately ﬁnding use in real physics.Fractional SuccessA NEW THEORY ... Prize in Physicsfor devising the original theory of the two-dimensional fractional quantum Hall effect, the discovery of the four-dimensional quan-tum Hall state is rather beautiful and a realbreakthrough. ... magne-sium-calcium ratio was the same all over the earth atany given time but var-ied from time to timeduring the past 600million years. Thatchange, the researcherssurmise in the Novem-ber...

scientific american - 2003 01 - the nanodrive

... collision, the South Pole–Aitken Basin is a 13-kilometer-deep gouge into the lunar crust that may ex-pose the moon’s mantle. It is the largest im-pact crater in the entire solar system. Thanks ... shorter-necked, large-headed plesiosaurs, a group called the pliosauromorphs,were built for high-speed pursuits on the open ocean. The longer-necked, small-headed ple-siosauromorphs, on the other hand, ... and his co-workers at the Universi-ty of Texas at Austin disputed the basic the- ory of negative index materials. They point-ed out that modulation wave fronts (such asthose in the front of...

scientific american special edition - 2003 vol 13 no3 - new light on the solar system

... on the Solar System SCIENTIFIC AMERICAN Volume 13 Number 3C2 SCIENTIFIC AMERICAN 284COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.28 SCIENTIFIC AMERICAN Updated from the Fall 1998 issue of Scientific ... cloud cover. The high-er reﬂectivity reduces the incoming solar en-ergy and hence the temperature. This neg-ative feedback acts as a thermostat, keeping the surface temperature moderate over ... that condensed from the presolar nebula, itformed at the highest temperatures. The planet’s dawn-to-dawnday, equal to 176 Earth-days, is the longest in the solar system, longer even than its...

scientific american - 1993 06 - tuning in the radio signals of ancient galaxies

... the wom-en in the rural areas have that same cy-cle, and they teach the same values totheir children. They teach their sons toorder; they teach their daughters thatthey must serve even their ... Moreover, the depth at which the measured proÞle departsfrom the undisturbed geothermal gra-dient is related to the time that climat-ic change began. The details of the pro-Þle between the ... chromosome.To their pleasure, theyrealized that previousgenetic studies had im-plicated roughly the same part of the chro-mosome in SCID.They decided to test the hypothesis that defects in the gam-ma-chain...

Xem thêm