scientific american - 1999 09 - t rex reexamined
scientific american - 1999 09 - t rex reexamined
... biodiversity, pre- dicts that without drastic action, two thirds of the world’s 300,000 plant species will be lost during the next cen- tury as their habitats are destroyed. Yet he believes that an international ... idea of restric- tions. They took the position adopted by the Federal Bureau of Investigation and argued that putting the informa- tion on the Internet is a security risk and that...
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scientific american - 1993 09 - special issue - life, death, and the immune system
... advocates can usually at best suggest when a treatment war- rants further examination. For most therapies, the institute states that Òe - cacy must be assessed in the context of a randomized trial.Ó ... patient with MAGE or its constituent peptides, along with mole- cules designed to strengthen immuni- tyÑthey might be able to create an ef- fective therapy for melanoma. Another way to Þght...
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scientific american - 1994 09 - conquering lyme disease
... and antihis- tamines bind to the cytochrome-P450 receptor sites. The result, he suspects, 22 SCIENTIFIC AMERICAN September 1994 bon dioxide. Pinatubo threw dust into the stratosphere that caused ... the mathematical language of science. ÒThat is what always seems to me the most remarkable thingÑthat the physical world obeys mathematics. The fact that mathematics works is extremely myste-...
Ngày tải lên: 12/05/2014, 14:58
scientific american - 1995 09 - 150th anniversary issue - key technologies for the 21st century
... U.S. Although oÛcials assert that they are on top of the situation, they admit they do not know the scope of the illegal im- ports and cannot predict their growth: agents estimate that in Miami the ... fact Òat- tractorÓ refers merely to a mathemati- cal pattern of behavior into which sys- tems tend to lapse. Alan Stein, a Manhattan-based psy- choanalyst who helped Goldstein orga- nize the .....
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scientific american - 1996 09 - special issue - what you need to know about cancer
... insulate a turkey’s head to the same extent that real feathers would. To find the right feather substi- tute, he needed birds related to turkeys but with feathers on their heads. Roosters fit the bill. ... separate- ly, by contacting the rating service directly to see if it has a rating at the URL of the document in question. This second option means that third parties can rate those sites th...
Ngày tải lên: 12/05/2014, 15:15
scientific american - 1997 09 - building doors into cells
... lay the groundwork. It is also possible, however, that the patients’ innate resis- tance to M-tropic strains somehow sped up the transition of M-tropic strains to hot T- tropic types able to establish ... star-studded, organized systems that we see today. To that end, Muxlow and others are teaming up again with their counter- parts at the VLA to study the extremely remote objects spotted by...
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scientific american - 1998 09 - a last look at laetoli
... TRACKS G 1-1 G 1-2 G 1-3 G 1-9 G 1-8 G 1-7 G 1-6 G 1-1 0 G 1-1 1 G 1-1 2 G 1-1 3 G 1-1 4 G 1-1 9 G 1-2 1 G 1-2 2 G 1-2 3 G2/ 3-1 G2/ 3-2 G2/ 3-3 G2/ 3-6 G2/ 3-5 TUFF BELOW FOOTPRINT LAYER FOOTPRINT TUFF GRABEN G2/ 3-7 G2/ 3-8 G2/ 3-9 G2/ 3-1 0 NORTHWEST GULLY FAULT ... worked with Tanzanian authorities to ensure that the Laetoli...
Ngày tải lên: 12/05/2014, 15:43
scientific american - 1999 01 - revolution in cosmology
... people staged a “virtual sit-in” to protest the govern- ment’s treatment of Zapatista rebels in Chiapas. The digital demonstrators tried to over- whelm targeted Web sites, in- cluding those of ... under- scores the power of the Internet. Last spring protesters by- passed the state-controlled media there by posting a Web site containing a database that kept track of the corruption of then ......
Ngày tải lên: 12/05/2014, 15:51
scientific american - 1999 02 - a fractual walk down wall street
... hurdle to applications for high- temperature superconductors —sub- stances that carry electricity without resis- tance above liquid-nitrogen tempera- tures —is that they generate magnetic whirlpoollike ... utility pole yard in Visalia, Calif. But, as often happens with pollutants that are heavier than wa- ter, the contamination continued to trick- le down. It threatened to spoil the town’s wa...
Ngày tải lên: 12/05/2014, 15:53
scientific american - 1999 03 - when venus erupted
... unless the Senate ratifies it. Opposition to the treaty is so strong that the Clinton administra- tion will not be sending it to Capitol Hill for a vote anytime soon. So with the Kyoto Protocol ... miniworkstation, the exten- sion locks onto the wrench or post and releases the pin. The other tools —and just about any- thing else the astronauts take outside — have attached loops, so that they...
Ngày tải lên: 12/05/2014, 15:56