ISSN:0031-9228    

DOI:10.1063/1.2805911

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.882073

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.882074

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

It was a relatively warm winter in the western Arctic this year; the lows were only ‐42°C. That was still chilly enough to sting the fingers and toes of the more than 150 scientists participating in the SHEBA project—a multiprong, yearlong international study of polar environmental conditions whose data‐gathering phase ended this October. (SHEBA stands for Surface Heat Budget of the Arctic Ocean.) The base of operations for the project was a Canadian icebreaker namedDea Groseilliersthat was intentionally frozen into a region of multiyear ice and set to drift with the ice pack. With the ship serving as a hotel (featuring, we're told, gourmet meals), power source, communications base and repair facility, researchers fanned out over the ice to deploy radiometers, launch balloons, poke instruments into the ice and even descend in diver's sear into the frigid ocean waters.

ISSN:0031-9228    

DOI:10.1063/1.882076

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The techniques of magnetic trapping and evaporative cooling of atoms to nanokelvin temperatures have led to Bose–Einstein condensation in alkali atoms and atomic hydrogen and to studies of ultracold atomic collisions. But none of the optical cooling methods has worked for molecules because it hasn't seemed possible to keep the molecules from being optically pumped into inaccessible states.

ISSN:0031-9228    

DOI:10.1063/1.882077

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

It's an intriguing idea: A steady rain of kiloton minicomets of loosely packed ice, pelting the top of the atmosphere at a rate of about a dozen per minute could, over geological time, account for most of the water in the oceans, and who knows what else. That's the picture suggested last year by Louis Frank and John Sigwarth at the University of Iowa, based on their observations with the Visual Imaging System (VIS), the Earth camera built by Frank and carried aboard NASA's Polar orbiter. (SeePHYSICS TODAY, July 1997, page 18.)

ISSN:0031-9228    

DOI:10.1063/1.882078

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The impressive performance of evolution as a design mechanism needs no belaboring. Physics, though, constitutes a larger reality that evolution can no more transcend than a cow can jump upward at escape velocity. Enzymes cannot act as Maxwellian demons, nor can birds turn off gravity. Physics limits life's designs no less rigidly than it constrains our own technology.

ISSN:0031-9228    

DOI:10.1063/1.882079

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In his 1998 State of the Union address. President Bill Clinton told Congress: We should enable all the world's people to explore the far reaches of cyberspace. Think of this: The first time I made a State of the Union speech to you, only a handful of physicists used the World Wide Web—literally, just a handful of people. Now, in schools, in libraries, homes and businesses, millions and millions of Americans surf the Net every day.

ISSN:0031-9228    

DOI:10.1063/1.882070

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The investigation of superconductivity in the presence of disorder began 60 years ago with the work of Alexander Shal'nikov at the Institute for Physical Problems in Moscow. The subject has played an ongoing role in condensed matter physics over the years. Interest has recently been heightened by the possibility that the disorder‐driven or magnetic‐field‐driven quenching of superconductivity in systems at the limit of zero temperature and two dimensions might be quantum phase transitions. That would link the physics of the superconductor‐insulator transition in thin films to other systems believed to exhibit quantum phase transitions—for example, helium‐4 in porous media, high temperature superconductors, Josephson‐junction arrays, two‐dimensional electron gases and various spin systems.

ISSN:0031-9228    

DOI:10.1063/1.882069

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.882082

出版商:AIP    

年代:1998

数据来源: AIP