ISSN:0031-9228    

DOI:10.1063/1.2806678

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.881800

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.881842

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.881844

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Last month in these pages we wrote, “Gamma‐ray astronomers expect that [the 28 February gamma‐ray burst] is but the first of many GRBs that will soon be revealing much more of themselves…” (page 17). “Soon” turned out to be an understatement. On 8 May, just as we were going to press, the new Italian‐Dutch BeppoSAX satellite recorded another GRB, one that will surely make its way into the textbooks.

ISSN:0031-9228    

DOI:10.1063/1.881802

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

This multiple‐exposure ultraviolet image, taken last September by the Visible Imaging System (VIS) aboard NASA's Polar orbiter, shows a 500‐km‐long trail of something roughly 10 000 km above the Atlantic, coming in toward Europe and shining brightly at 130.4 nm, a prominent UV emission line of atomic oxygen. The VIS has also recorded many such trails at 308.5 nm, a characteristic wavelength of hydroxyl‐radical fluorescence.

ISSN:0031-9228    

DOI:10.1063/1.881803

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

For roughly the last two decades, it has generally been believed among those interested in two‐dimensional disordered electron systems that, in zero magnetic field, such systems do not undergo a metal‐insulator transition at 0 K. In an influential 1979 paper, Elihu Abrahams, Philip Anderson, Donald Licciardello and T. V. Ramakrishnan, who became known as the Gang of Four, had used scaling arguments, assumed there were no electron‐electron interactions and found that an electron in a two‐dimensional random potential at 0 K would not diffuse. So, if the temperature were lowered toward 0 K, no transition from insulator to metal would occur in a disordered system. Even if the twodimensional electron systems were conducting at high temperatures, the disorder and the two‐dimensionality would be sufficient to localize the electrons, preventing metallic behavior atT = 0.

ISSN:0031-9228    

DOI:10.1063/1.881804

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Ionce asked my father why he chose physics when he started at MIT. “Everybody said it was the hardest course, so I decided to do it.”

ISSN:0031-9228    

DOI:10.1063/1.881805

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Cosider the following Experiment: Take a carton of eggs, open the lid and accelerate the carton with a sudden jerk. If you try this at home, you will find that the outcome strongly depends on the magnitude of the acceleration (the authors are not responsible for the results).

ISSN:0031-9228    

DOI:10.1063/1.881845

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Electromagnetically induced transparency is a technique for eliminating the effect of a medium on a propagating beam of electromagnetic radiation. EIT may also be used, but under more limited conditions, to eliminate optical self‐focusing and defocusing and to improve the transmission of laser beams through inhomogeneous refracting gases and metal vapors, as figure 1 illustrates. The technique may be used to create large populations of coherently driven uniformly phased atoms, thereby making possible new types of optoelectronic devices.

ISSN:0031-9228    

DOI:10.1063/1.881806

出版商:AIP    

年代:1997

数据来源: AIP