摘要:

Superconductivity and ferromagnetism were considered exclusive phenomena for many decades. Ever since Kamerlingh Onnes' discovery that strong magnetic fields will destroy superconductivity it had been assumed that the large internal, or Weiss field, in a ferromagnet would never permit the occurrence of superconductivity. In the case of the magnetic elements, chromium, manganese, iron, cobalt, and nickel, this point of view certainly seems justified, as none of them has as yet been shown to be superconducting. And yet, whenever two phenomena seem to exclude one another so entirely, it is frequently because similar, if not identical, mechanisms are responsible.

ISSN:0031-9228    

DOI:10.1063/1.3050750

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The purpose of this paper is to present a rapid survey of the statistical properties of spectra, using both atomic spectral data and nuclear spectral data. In many cases, only one kind of relevant data exists; for example, very little is known about atomic‐particle transition‐probability data, so in such areas we must confine our attention to nuclear data. When both atomic and nuclear data are available, we have tried to select those data which are usually not treated according to the general approach of this paper. Throughout our discussion, then, we will be mainly emphasizing analogies and the manner of handling different sorts of data according to the spirit of this paper.

ISSN:0031-9228    

DOI:10.1063/1.3050751

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Shortly after the study of astronomy by radio techniques began in earnest, a basic problem arose. Three “sources” of radio flux had been delineated: the sun, the cosmic‐noise background, and the discrete sources (radio stars). Were the discrete sources variable, as the sun showed evidence of being, or was the atmosphere modulating fixed‐flux sources? The first answer was that the radio‐star sources exhibited intrinsic fluctuations in intensity, but studies in Australia and England utilizing spaced receivers indicated that the earth's ionosphere and troposphere produced effects similar to the “twinkling” of visible stars. The study of “twinkling” or scintillation was the first of the upper‐atmospheric effects to be investigated in detail.

ISSN:0031-9228    

DOI:10.1063/1.3050752

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The Regional Counselor Program was launched jointly by the American Association of Physics Teachers and the American Institute of Physics in October 1961. The broad objective of the program, as stated in the initial news release dated October 10. 1961, is “to improve high‐school teaching of physics”. This objective it shares with other agencies and groups, and with Admiral Rickover! Perhaps the most notable of these is the Physical Sciences Study Committee, which has been in operation a great deal longer and has evidenced its activity by the production of what many of us believe to be an outstanding text for the teaching of physics. The unique contribution of the AAPT‐AIP Regional Counselor Program is in recognizing that any major improvement in the teaching of physics must come about through local action, through the efforts of people well known in their communities, and to a large extent with the resources we already have. Good as they are, the PSSC texts will be to no avail if they are not adopted widely through the high schools. This will require that constant encouragement be given school boards, teachers, and administrators, as they encounter the many problems inherent in any program to improve teaching in physics. It is evident that encouragement and help must be primarily local.

ISSN:0031-9228    

DOI:10.1063/1.3050753

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3050755

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3050756

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3050761

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3050762

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3050763

出版商:AIP    

年代:1963

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3050764

出版商:AIP    

年代:1963

数据来源: AIP