ISSN:0031-9228    

DOI:10.1063/1.2805868

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.882319

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.882321

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.882322

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

It has long been known that as tectonic plates pull apart along the mid‐ocean ridge system, the mantle wells up to fill the gap. Partial melting of the mantle produces magma that percolates upward to the surface and solidifies into new crust within a few kilometers of the ridge. But the details of this process have been a mystery: Over what volume is the mantle melted to form this magma? What is the concentration of the melt? How connected are the pockets of molten material? To answer such questions, an international collaboration designed the Mantle Electromagnetic and Tomography (MELT) experiment, placing seismometers, electrometers and magnetometers on the ocean floor to span the midocean ridge known as the East Pacific Rise (see figure below). After several years of gathering and analyzing data, members of the collaboration presented their results at the Boston meeting of the American Geophysical Union at the end of May.

ISSN:0031-9228    

DOI:10.1063/1.882323

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

As microelectronic devices continue to shrink, submicrometer‐sized contaminants pose a serious threat to semiconductor yields and performance—and thereby to the profits of the nearly $200 billion a year industry. Chemical analysis of these tiny particles can suggest remedies for avoiding contamination by helping to pinpoint its sources. One of the most successful microchemical analysis tools combines electron microscopy with spectroscopic analysis of x rays excited in the target impurity by the microscope's electron beam. Unfortunately, the choice of x‐ray detector has traditionally involved a trade‐off between energy resolution and speed. So the semiconductor industry—where time equalsa lotof money—has often had to supplement spectrometry with educated guesswork. Now, John Martinis, Kent Irwin, Gene Hilton and David Wollman, working at the National Institute of Standards and Technology facility in Boulder, Colorado, have developed an x‐ray detector that they hope will remove some of that guesswork.

ISSN:0031-9228    

DOI:10.1063/1.2805869

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Imagine you are in the last stages of typing your thesis, the year is 1980, and it's a hot, hazy summer afternoon, a thunderstorm brews on the horizon. Tense and tired, you have forgotten to save the document on your hard disk. Suddenly, lightning strikes! Your computer shuts down. Your final chapter is lost.

ISSN:0031-9228    

DOI:10.1063/1.882324

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In today's world, it is nearly impossible to avoid contact with electromechanical sensors and actuators over the course of the day, although we rarely recognize them. They drive the keyless entry systems, the light switches that respond to sound or motion, the detectors in cars that determine whether seat belts are fastened and the sound‐receiving and sound‐generating parts of the telephone, to name just a few examples.

ISSN:0031-9228    

DOI:10.1063/1.882325

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Quantum mechanics is very puzzling. A particle can be delocalized, it can be simultaneously in several energy states and it can even have several different identities at once. This schizophrenic behavior is encoded in its wavefunction, which can always be written as a superposition of quantum states, each characterized by a complex probability amplitude. Interferences between these amplitudes occur when the particle can follow several indistinguishable paths. Any attempt to determine which trajectory it “actually takes” destroys these interferences. This is a manifestation of wave—particle complementarity, which has recently been illustrated in textbook fashion by several beautiful experiments.

ISSN:0031-9228    

DOI:10.1063/1.882326

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.882317

出版商:AIP    

年代:1998

数据来源: AIP