ISSN:0031-9228    

DOI:10.1063/1.2811106

出版商:AIP    

年代:1989

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2811107

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A membrane that is not rigid in the plane, or has zero in‐plane shear modulus, is said to be fluid; one that does have a nonzero shear modulus in the plane is said to be solid‐like. A fluid membrane shaped, say, like a rectangle will be easily deformed when antiparallel forces are applied along two of its parallel edges. In many cases the interesting excitations, or conformations, of a fluid membrane arise from out‐of‐plane bending.

ISSN:0031-9228    

DOI:10.1063/1.2811108

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

By international agreement, new practical reference standards for the volt and the ohm, based respectively on the Josephson effect and the quantum Hall effect, will be adopted worldwide on 1 January 1990. Until now, national standards laboratories have been using wirewound resistors as practical reference standards for the ohm. Practical reference standards for the volt, on the other hand, have been based on the Josephson effect since the early 1970s. But four different such standards are in use in different countries, and their values all differ significantly from the volt as defined in the Syste`me International d'Unite´s (SI), the internationally accepted system of measurement units.

ISSN:0031-9228    

DOI:10.1063/1.881176

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

In the past decade a new wave of apprehension about public education—especially science education—has come to the fore. A spate of recent studies has heightened the sense of unease by suggesting a lack of improvement in science proficiency among succeeding cohorts of US students and a slippage in international standings in comparative tests of science knowledge. Such widespread alarm over the academic health of our nation is a relatively new development. Until two generations ago the United States was widely regarded as a pioneer in instituting and extending free and universal public education. Education was extolled as a national resource, and a literate populace was regarded by many as critical to the maintenance of political democracy, to the attainment of a society committed to equal opportunity and the reward of merit, to the pursuit of a robust and internationally competitive economy and to the preservation of a strong national defense.

ISSN:0031-9228    

DOI:10.1063/1.881177

出版商:AIP    

年代:1989

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2811109

出版商:AIP    

年代:1989

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2811110

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Someone—I do not remember who—discovered that this is the 25th anniversary of the first Texas Symposium on Relativistic Astrophysics. The discovery is the more remarkable since the conference is held every two years and the number 25 is, I believe, odd. Undoubtedly, this fact could, should and presumably will be explained by historians of science—thus I will not bother.

ISSN:0031-9228    

DOI:10.1063/1.881214

出版商:AIP    

年代:1989

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2811111

出版商:AIP    

年代:1989

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2811113

出版商:AIP    

年代:1989

数据来源: AIP