摘要:

This, the second of two articles, gives an account of the experimental and theoretical work on which our present extensive knowledge of the sensitivity and analytical properties of the ear is based. Masking phenomena are surveyed and shown to indicate the broad asymmetrical pattern of response of the cochlea that has been observed physically. In all response activities, the ear behaves as though it involves a variable-frequency band-pass analyser with critical bandwidths. In many instancem of response to signals such as pure tones and speech it appears that the Uncertainty Principle for acoustics applies.

ISSN:0010-7514    

DOI:10.1080/00107516808220088

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The advantages of using very high voltages for electron microscopy are reviewed, in respect of greater specimen thickness and reduced chromatic aberration. For polymers and possibly with living material, the lower radiation damage in a given thickness is also valuable. The special problems in the design and construction of microscopes operating up to 1 Mv are discussed. We are still in a stage of rapid development, and some possibilities for the future are outlined. The main areas of application of high voltage microscopes are beginning to be defined; some examples are given of what has been done with the Toulouse and Cambridge microscopes to date.

ISSN:0010-7514    

DOI:10.1080/00107516808220089

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The critical temperature,Tc, for all presently known superconductors does not exceed 20°K. This fact obviously limits the range of applications of superconductivity in technology in a very fundamental way. On the whole, the reason why the value ofTcfor ‘ordinary’ superconductors should not exceed 20–40 °K is fairly well understood on the basis of the existing theory of superconductivity. At the same time, there apparently could exist high temperature superconductors for which the temperatureTcwould reach hundreds of degrees, or at least liquid air temperature. Possible means of producing high temperature superconductors are considered in this article. Special attention is paid to what can be called the exciton mechanism of superconductivity.

ISSN:0010-7514    

DOI:10.1080/00107516808220090

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Open channels exist between the rows or planes of atoms in a crystal. In experiments with carefully defined beams of energetic ions it is possible to inject particles into these channels. There they travel with relative ease, being reflected back and forth between the channel walls by a correlated series of atomic collisions. The main types of experiment on this phenomenon are summarized and the classical theory is developed. Classical treatment is not adequate for light particles, such as electrons or positrons because their de Broglie wavelength is greater and a wave mechanical version is outlined in a form which is also suitable for describing protons. This confirms that for heavy particles classical theory can explain any experiments performed so far, but it is just possible that the interpretation of more precise proton experiments may require wave mechanics.

ISSN:0010-7514    

DOI:10.1080/00107516808220091

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A number of important physics curriculum projects have produced course materials, or are in the process of doing so, for different levels of science education in the United States of America. This article surveys the scene under such headings as the Origins, the Aims, the Patterns of Construction, the Teaching Methods, the Teacher Training and the Evaluation Techniques pertaining to each of ten selected projects. An attempt is then made to draw inferences, from the American work, that are relevant to the present and future position of physics education in Britain. It is observed that action on many of these inferences would be consistent with the recommendations of the ‘Deinton Report’.

ISSN:0010-7514    

DOI:10.1080/00107516808220092

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Selected Papers on the Transfer of Radiation. Ed. H. Menzel. (Dover Books (Constable), 1966.) [Pp. iv + 269.] 24s.

ISSN:0010-7514    

DOI:10.1080/00107516808220093

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808220094

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor