ISSN:0031-9228    

DOI:10.1063/1.2809760

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809763

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809765

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809766

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

16 July issue ofPhysics Lettersbrings us the eagerly awaited report of the first results from the Gallex solar neutrino experiment. The Gallex detector, with its 30 tons of gallium, sits in a laboratory underneath the Gran Sasso d'ltalia, a 2900‐meter peak in the Apennines northeast of Rome. The suspense was heightened last fall when the SAGE collaboration, which operates the only other gallium detector, reported that it had seen no clear evidence of any solar neutrinos in its first seven months of running. The name Soviet‐American Gallium Experiment may now seem out of date, but the experiment, located under a mountain in the Caucasus, goes on. SAGE is now operating with 57 tons of gallium.

ISSN:0031-9228    

DOI:10.1063/1.2809767

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A once dark region of the electromagnetic spectrum is now becoming very bright. The soft‐x‐ray spectral region, nominally extending from wavelengths of several angstroms to several hundred angstroms and including photon energies from tens of electron volts to several thousand electron volts, is providing many new research and development opportunities in the physical and life sciences and in industry. The move toward shorter wavelengths is driven in part by the desire to see and write smaller features. But the numerous and distinct atomic resonances in this region of the spectrum also provide for elemental identification and, in some cases, chemical sensitivity. (See the article by Bernd Crasemann and Francois Wuilleumier inPHYSICS TODAY, June 1984, page 34.) Developments in x‐ray optics and new sources of highbrightness, partially coherent radiation make it possible to study materials and biological samples with feature sizes of several hundred angstroms.

ISSN:0031-9228    

DOI:10.1063/1.881314

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Two decades ago US women earned about 4&percent; of the nation's physics PhDs. Today, they earn about 5&percent;. Although discussed in various forums in recent years, the low representation of women in physics persists. The problem is especially perplexing given the dramatic increases in the percentages of women in other sciences and in engineering.

ISSN:0031-9228    

DOI:10.1063/1.881315

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The growth of commerce around the end of the 16th century created a need for large amounts of numerical calculation. the increasing understanding of astronomical phenomena around the same time also depended on accurate computation. the difficulty of accurately performing large amounts of tedious numerical work by hand stimulated Leibniz, Pascal and others to invent mechanical adding and multiplying machines in the 17th century. (See figure 1.) the speed and complexity of mechanical computation were limited by inertia, friction, size and the difficulty of transmitting information very far. the development of electrical technology led to the introduction of electrical components in peripheral parts of computing machines, such as motors in place of hand cranks. Major improvements in performance, however, had to await the electrical representation of information

ISSN:0031-9228    

DOI:10.1063/1.881316

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809768

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809769

出版商:AIP    

年代:1992

数据来源: AIP